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October 3

Centre of mass of the Earth

Does the center of mass of the Earth change its position with respect to the plane of the equator and its axis. —Preceding unsigned comment added by 113.199.208.88 (talk) 08:51, 3 October 2010 (UTC)

Yes. According to this site, "The Earth's centre of gravity constantly changes position within a three-centimetre cube in response to mass redistributions on the surface of the globe, caused by shifting masses within the ocean and by soil moisture, snow cover and groundwater."

I would also have expected some movement due to convection currents in the liquid portions of the mantle and core (see Structure of the Earth) moving around material of slightly different densities, but I haven't found a specific reference for that (yet). 87.81.230.195 (talk) 12:36, 3 October 2010 (UTC)

And what is this amazing centre of gravity constraining three-centimetre cube is made out of? Nickel-iron alloy, presumably. -- 111.84.196.147 (talk) 13:17, 3 October 2010 (UTC)

As I'm sure you know, the '3cm cube' is just a visualization trick. in fact, the actual center of gravity of the Earth is probably only definable in terms of a 3-dimensional confidence interval, which probably has a shape (at any given confidence level) like a flattened sphere or fat disk (on the assumption that most of the variation is in the equatorial plane, and less is in the axial plane) --Ludwigs2 19:56, 3 October 2010 (UTC)

We have an article on polar motion which seems to be what you're looking for. There is also an effect called nutation, which is due to the moon. Physchim62 (talk) 00:40, 4 October 2010 (UTC)

What about the tides from the moon? Do they cause any changes to radial velocity relative to the Sun, within the Earth-moon gravitational centre system? ~AH1^(TCU) 14:34, 3 October 2010 (UTC)

The answer to the original question is no. Both the equator and the axis of rotation pass through the center of mass by definition. If the center of mass moves (in relation to something else, like the surface of a large part of the Earth), then the equator and/or the axis of rotation move with it. --Anonymous, 06:35 UTC, October 4, 2010.

The post just above by anonymous would apply if the Earth was a prefect sphere. However, in reality (as one is taught in school geography lessons) it is a slightly pear shaped oblate spheroid giving ellipsoid that is triaxial . Thus the 'geometric' and 'centre of mass' is not necessarily going to coincide. Satellite ranging has already shown that for Mars, the centre of mass and the geometric centres do not coincided exactly either. The World Geodetic System 84 gets round this problem by ascertaining the centre of gravity (mass) and generating a perfect theoretical gravimetric ellipsoid as a datum from which all other spheres can be compared.--Aspro (talk) 08:47, 4 October 2010 (UTC)

No, I was talking about the real world, not a perfect sphere, and the center of mass, not any sort of geometric center. --Anonymous, 16:02 UTC, October 4, 2010.

The OP has said nothing about ignoring the cartographers equator and axis and geometric shape, and so as it stands it is a reasonable question. If he was taking about your interpretation of equator and axis there would be no point in asking it. He is asking about the 'real' world which is the point of his question. Your second post also contradicts your first. To my mind some people do ask pointless questions here but you appear to be prejudging either his motives or his intelligence, either which is in my view despicable.--Aspro (talk) 18:44, 4 October 2010 (UTC)

The question specificially defined what it was asking about -- the equator and axis in relation to the center of gravity. I answered in those terms after other people answered in other ways. I don't see how it can be construed as inappropriately judgemental to answer the question that was asked, but I'll just say that I was not intending to malign anyone. --Anonymous, 03:17 UTC, October 5, 2010.

So it seems your just begging the question, Also, you haven't indicated what part you disagree with in the first explanation which which covers what earth scientists are discovering about the real world. Suppose you might as well just argue with yourself then. --Aspro (talk) 21:52, 7 October 2010 (UTC)

stelar cartography

I have a map of the galaxy as seen from what I will, for want of a better term, call above. However, this uses a system of coordinates based on angles from a line passing from the earth to the centre of the galaxy, rather different to that used to determine where stars are from earth. How, then, would I go about plotting the location of a particular star on this map using the coordinates given for its location within the sky?

148.197.121.205 (talk) 12:10, 3 October 2010 (UTC)

Does celestial coordinate system help? --81.153.109.200 (talk) 12:16, 3 October 2010 (UTC)

(EC) The article Celestial coordinate system has links to more detailed descriptions of these two systems - the Galactic and the Equatorial systems - (as well as other), and a section explaining how to convert between the Equatorial and Horizontal systems, but not explicitly the conversion you need. However you may be able to use the correct terminologies in these articles to help search for the appropriate conversion, which I'm sure is out there.

[Addendum] Doh! See the first external link in the Galactic coordinate system article! 87.81.230.195 (talk) 12:21, 3 October 2010 (UTC)

Bio engineering

Does bio engineering have good, strong prospects in the future? I know bio engineering is a broad field, but I have applied for undergraduates at the moment so a rough explanation would suffice. And also microbiology. Thanks.--119.155.118.204 (talk) 15:29, 3 October 2010 (UTC)

The article biological engineering explains the wide and robust areas of research. Is there a specific topic you wanted information about? -- kainaw™ 16:02, 3 October 2010 (UTC)

The prospects for both fields are excellent -- bioengineering in particular is bound to grow vastly in the next couple of decades. The prospects for an individual going into a field also depend on the amount of competition, though, and I don't know anything about that. Looie496 (talk) 16:22, 3 October 2010 (UTC)

Also take a look at biochemical engineering and biogeochemistry. ~AH1^(TCU) 18:17, 3 October 2010 (UTC)

And biomedical engineering. Regards, --—Cyclonenim | Chat  21:06, 3 October 2010 (UTC)

How does a rocket "steer"?

In the article on the Chinese Chang'e 1 lunar probe, there's a picture of the rocket carrying the probe blasting off. The rocket seems to have only one engine and no fins. How does the rocket adjust its direction of travel? —Preceding unsigned comment added by 96.227.60.253 (talk) 16:24, 3 October 2010 (UTC)

See gimbal#Rocket engines -- Finlay McWalter ☻ Talk 16:40, 3 October 2010 (UTC)

This page has some nice diagrams and animations illustrating the principle. I guess because they are NASA we could import them to Wikipedia? --Mr.98 (talk) 16:43, 3 October 2010 (UTC)

Once launched, spacecraft use a reaction control system to manoeuvre. For some operations, like moving from a Lunar orbit into a return-to-Earth trajectory, spacecraft orient themselves with the RCS (which tends to be a pretty low-powered affair) and then engage a larger rocket engine for the big-deltaV burn. -- Finlay McWalter ☻ Talk 16:45, 3 October 2010 (UTC)

I should mention that, while gimballing is very popular, it's not the only option. Gimballing requires either rotating the whole engine (which is pretty impractical for a serious rocket) or rotating the engine bell (which requires an articulation, which can be tricky to get right given the pressures and temperatures involved). Other options include vernier rockets to turn the rocket (they're a bit like the RCS, above) or putting robust vanes into the exhaust stream (that's how a V-2 rocket steered]]). Lastly you might consider movable fins (or fins with movable flaps) but they become ineffective in the higher reaches of the atmosphere, so they're mostly found on low-level devices like short-range missiles. http://exploration.grc.nasa.gov/education/rocket/rktcontrl.html has more. -- Finlay McWalter ☻ Talk 16:54, 3 October 2010 (UTC)

Skimming the lengthy users' manual for the Long March 3A rocket that launched Chang'e 1, it seems the first stage is steered by gimballing (and the wording suggests they do gimble the whole engine, despite my claim that this is impractical☻), and that the second stage is controlled by verniers. The first stage has little fins, but these appear to be fixed and so only for basic stabilisation. -- Finlay McWalter ☻ Talk 17:04, 3 October 2010 (UTC)

Fins would in any case I presume be only effective while the trocket was travelling through the atmosphere, which is a very small proportion of its journey. --rossb (talk) 17:55, 3 October 2010 (UTC)

Rockets spend a sufficient time at a low enough altitude that some designers have felt it beneficial to include aerofins; in some cases steerable ones. Saturn V had aerofins (although the article says that future flights might have removed them, as they "turned out to provide little benefit when compared to their weight". The LM3a has them, and the users' manual for the Soyuz-U says "Attitude control is carried out through two movable vernier thrusters and one aerofin [that's for each of the 4 boosters]. Three-axis flight control is made possible through these eight engines (two per booster) and four aerofins (one per booster)". N1 didn't and Ariane doesn't (as far as I can tell). Indeed it doesn't seem worth the bother, but who am I to argue with Von Braun and Korolyev :) -- Finlay McWalter ☻ Talk 18:38, 3 October 2010 (UTC)

I'm going to jump in with a follow-up question of my own: how do they control the rocket attitude just at launch? It seems to me that even a tiny imbalance in the thrust while it's sitting still or barely moving would tip the whole thing over. This seems much different than guiding the rocket in flight. Franamax (talk) 19:14, 3 October 2010 (UTC)

The engines gimbal even while it's still on the stand. If you watch a video of an Apollo or Shuttle launch, you see the main engine bells move around after they light, as the engines take over responsibility for keeping the vehicle righted from the stand. For a second or so the rocket hovers over the blast pit before it lifts. It's probably easier than in flight, because there's no dynamic pressure imbalance trying to pitch the rocket. This kind of dynamic hover behaviour is more evident in rockets like Delta Clipper and Pixel. -- Finlay McWalter ☻ Talk 20:32, 3 October 2010 (UTC)

They had computers that could handle that — reliably — in the 1960s? --Trovatore (talk) 20:54, 3 October 2010 (UTC)

Seems like a pretty basic feedback-based system: "gyroscopes in nose are reading tilts of (x,y) (or even better, are reading change in that direction), start moving rear thruster more in the direction of (x,y)". As long as rocket is tilted in that direction, the thruster will keep pushing more and more in that same direction until there's just enough torque around the center-of-gravity to start correcting the tilt. It works fine as long as you're dealing with "small" changes. If you tilt too far over and/or don't have limits on the rates of change, gets scarily easy to over-compensate and swing out of control...just like driving on ice. All sorts of inertial guidance systems even for following a complex route are at heart just a difference amplifier that reports "target-value minus current-value" and the result piped to whatever mechanism steers "away from off-course". I've seen the airplane analog ("adjust flaps/rudder to make the plane do exactly what the pilot says to do", which means need feedback-control to make "actual plane" match "pilot action" to negate wind effects) in intro-engineering courses. DMacks (talk) 21:28, 3 October 2010 (UTC)

Never mind 1960s, a V2 rocket had to do that in the 1940s, so clearly no computer. It's a damped feedback system running off a gyroscope (over damp it and it's underreactive and a breeze blows it into the stand; under damp it and it over-reacts and does a little somersault into a school). What's impressive is not that they could do this in the 1960s with transistors, but that they could do it in the 1940s with, well, I don't know. Baling wire and little pulleys, perhaps :) -- Finlay McWalter ☻ Talk 21:11, 3 October 2010 (UTC)

There is a film for the V1 rocket on youtube (watch?v=HQccOvNG_ZY) which gives the pneumatic steering mechanism for the V1. There is a gyroscope which is driven by pressured air in a tank. The whole "guiding system" is pneumatic. So you would need no computer or even electricity for the guidance. --Stone (talk) 06:51, 4 October 2010 (UTC)

That's why they call it rocket science! Actually, this is control theory, (arguably the most important subset of rocket science). For every time-step "t", what set of input signals are necessary (valve settings; mechanical actuators; and so on), are required to guarantee stability, both mechanically and thermodynamically, for the rocket? The difficulty is that certain outputs (like rocket attitude and real-time thermodynamics of the combustion chamber) are impossible to know exactly until the instant of ignition; so a sophisticated bit of engineering goes in to providing a feedback loop from sensors back to the control algorithm. Control theory was designed long before engineers had knowledge of computers; very sophisticated systems can be built using simple electronic amplifiers and even mechanical governors. Now that everything is digitized, we can control at higher frequencies and to higher degrees of precision; in the case of rocketry, though (especially the attitude-control of large rockets), many parameters are physically large - so the relevant frequencies are very low (maybe tens of hertz). For this low-frequency control, gigahertz-speed computers aren't needed. On the other hand, the thermodynamics inside the combustion chamber can occur very fast, so it is useful to monitor it at very high speeds. However, control of these parameters is limited - valves that are controllable at hundreds of hertz do not exist, so this limits the utility of a fast computer. Safety and "emergency shutdown" has improved since the 1950s, though, as unstable combustion can now be detected mere nanoseconds after the chemistry starts going haywire, and a computer can make a decision (for example) to shut down or detonate the rocket before an uncontrolled flight becomes catastrophic. Nimur (talk) 18:44, 4 October 2010 (UTC)

The Merlin rocket engines of SpaceX's Falcon 9 (next launch expected in November), while gimballed, also pivot their turbo-pump gas generator exhaust for roll control. -- ToE^T 00:24, 4 October 2010 (UTC)

You may also wish to read Pendulum rocket fallacy. Ariel. (talk) 01:09, 4 October 2010 (UTC)

Ensembl sucks as*!

Resolved

 – Asked and answered. That the questioner doesn't want to read the answer is not a refdesk concern. DMacks (talk) 19:23, 3 October 2010 (UTC)

What are the alternatives? --178.98.78.190 (talk) 17:03, 3 October 2010 (UTC)

Uh. doesn't the article clearly say in the lead? Nil Einne (talk) 17:45, 3 October 2010 (UTC)

I don't read the articles; they're full of inaccuracies. But thanks. :) --178.98.78.190 (talk) 18:26, 3 October 2010 (UTC)

Nil Einne I just checked, the article lead doesn't say it sucks as* at all! Should we add that in? ;) Franamax (talk) 19:18, 3 October 2010 (UTC)

Wikipedia is not censored, so we should expand the wild-card to its actual value, which I expect is 'asphalt', or possibly 'asymptotes'. --Ludwigs2 19:59, 3 October 2010 (UTC)

More likely to be Asperger's syndrome... Physchim62 (talk) 20:17, 3 October 2010 (UTC)

If you can find a reliable source perhaps. On a related note, when asking for alternatives it's generally better to explain in more detail what your problems are, since it may enable people to give better answers. To give a simple example, even if we know Ubuntu 'sucks as', it doesn't help us know which of the hundreds or whatever Linux distros may suck less for you. Nil Einne (talk) 06:04, 4 October 2010 (UTC)

Global oxygen production of Algae

I am looking for reliable sources giving or commenting on estimates of the percentage of global atmospheric oxygen produced by Algae. I mean Algae, as they are defined in the article's lede: excluding the prokaryotic blue or blue-green "Algae". Thank you in advance, any help is appreciated (including references that say it is impossible to give a meaningful estimate).---Sluzzelin talk 17:05, 3 October 2010 (UTC)

This article states about 60%, might be a starting point for further searches. PЄTЄRS J VЄСRUМВА ►TALK 17:59, 3 October 2010 (UTC)

On a side note, the global measured population of plankton, which includes eukaryotes including plant algae has declined by 40% within the last six decades. ~AH1^(TCU) 18:14, 3 October 2010 (UTC)

Thanks to both of you. ---Sluzzelin talk 08:19, 5 October 2010 (UTC)

Masturbation

Will stopping or declining of masturbation effect in increasing one's level of testosterone and, subsequently, more male-like behaviour? —Preceding unsigned comment added by 83.31.134.230 (talk) 19:27, 3 October 2010 (UTC)

Perhaps it will do the opposite. --178.98.78.190 (talk) 20:24, 3 October 2010 (UTC)

No it will not. I think it would probably do the opposite. It will, however, increase the amount of ejaculate next time you ejaculate, as it's stored up.--92.251.236.197 (talk) 20:28, 3 October 2010 (UTC)

Lack of orgasm might cause increased testosterone level and increased sexual drive. Edison (talk) 00:13, 4 October 2010 (UTC)

As our article on testosterone points out, variations in levels are due to a much wide range of causes than frequency of orgasm. Physchim62 (talk) 00:43, 4 October 2010 (UTC)

As an aside, there is some evidence that regular ejaculation reduces your chances of getting some types of prostate cancer. See Prostate_cancer#Ejaculation_frequency. There is no requirements as to the cause of this ejaculation, so whether it is done alone or in conjunction with another consenting adult, the benefits are the same. This effect has not been explained mechanistically, but it may have something to do with regulating testosterone levels in the body. --Jayron32 16:17, 4 October 2010 (UTC)

October 4

SI: The Logical System?

In my chemistry textbook the SI (or metric) is referred to as the 'logical system of measurement'. But how logical is it, really? Far more than the wretched English system (or so I've been told since kindergarten), but not as logical as they could be. The different unprefixed units do not coincide: a gram is intuitively "small" whilst a litre and a metre are intuitively "middle-sized" or even "somewhat large". So my question is: when the French scientists were inventing the SI, why didn't they make 1 m³ = 1 l, which would also be 1 kg of some common substance (most likely water)? Wouldn't this be more logical? Thanks. 24.92.78.167 (talk) 00:44, 4 October 2010 (UTC)

A partial answer is that they were chosen to be at least within an order of magnitude to the traditional units being used in Europe at the time. For example a Liter is pretty close to both a french pint and a french litron. I'm sure this made it a lot easier for people to adopt the new units. (The french pint is almost double the American pint, in case you were wondering.)

This system was originally designed to simplify trade, not specifically science, so it was built around the needs of whatever merchants needed the most. APL (talk) 01:15, 4 October 2010 (UTC)

I agree with APL's answer, with the exception that the litre is not an SI unit, though it is commonly used with other SI units. -- Scray (talk) 03:48, 4 October 2010 (UTC)

Ah, you're right. Stupid of me. ... ... Still, it is a metric system unit. So I still feel justified in using it in a discussion about the origins of SI units. APL (talk) 04:34, 4 October 2010 (UTC)

What is logical to one person is not logical to another. Consequently I think it would be impossible to contrive a system of units that would be universally considered logical. For example, if one cubic metre was equivalent to one litre, and one litre was about the size of the present litre, the metre would be only one tenth of its present size — one new metre would be equal to the present decimetre. This might be logical to scientists working on a small scale in laboratories, but it is unlikely to be logical to sailors and travellers who would find a day's journey measured in numbers ten times greater than the present numbers. A man can walk ten or twenty kilometres during the course of a day's work. He is unlikely to find it logical if he found himself walking one or two hundred kilometres in a day's work. Dolphin (t) 05:43, 4 October 2010 (UTC)

Only because he is accustomed to 100 km being a very large distance... Googlemeister (talk) 13:42, 4 October 2010 (UTC)

It's worth remembering the gram is not the SI base unit of mass. The kilogram is. This is generally accepted as an unfortunate artifact of history. For some history see [1] (surprisingly I couldn't see much coverage of this in our articles). Nil Einne (talk) 05:55, 4 October 2010 (UTC)

I think the explanation for why such a small size was chosen for the gram must be that the prefixes for scaling originally ran only from milli- (1/1,000) to kilo (1,000). If the kilogram had been named the gram, there would have been no names available for any units smaller than what we actually call a gram -- and presumably these were needed even then in fields like chemistry and medicine. --Anonymous, 06:44 UTC, October 4, 2010.

Our Grave (unit) article does discuss this, but perhaps some of it should be folded back into the kilogram article. CS Miller (talk) 11:27, 4 October 2010 (UTC)

Thanks. I thought I remembered reading something before but didn't find anything in the obvious places so decided I remembered wrong. I skimmed too vast so missed the mention of grave in kilogram. Nil Einne (talk) 13:57, 4 October 2010 (UTC)

I think "logical" here just refers to the ease of conversion between measures. If you want something "more logical", you can have a look at Planck units, but I doubt those are convenient for everyday use... Jørgen (talk) 07:19, 4 October 2010 (UTC)

Offtopic, but do people really walk 10 or 20 km during a day's work? --Chemicalinterest (talk) 11:22, 4 October 2010 (UTC)

I wrote A man can walk ten or twenty kilometres during the course of a day's work. Your question is off-topic. Dolphin (t) 11:25, 4 October 2010 (UTC)

10-20 is easy for some professions. I used to do that much in one shift. I used to know one woman who, if she didn't do something like 50 miles in a week, would make it up on the weekends. She rarely had to do any "extra" walking on the weekends to get to that figure. Additionally, some mail carriers probably do at least that. Dismas|^(talk) 11:50, 4 October 2010 (UTC)

The SI and the metric system in general is logical only insofar as all base units can be converted to any other by multiplying or dividing by a multiple of ten. Math becomes trivial when all you have to do it move a decimal point. As with any system, it needs to balance its usability from a mathematical perspective, and from a practical perspective. A measurement system isn't very useful if every measurement in it requires really huge or really tiny numbers. There are some base metric units which suffer from this problem, the pascal is an impractically small unit of pressure, which is why we use bar or kilopascal. Grams are impractical when weighing anything large (like, say, you) , so we use kilograms in SI. See also cgs system for details on a related system of measurement for small items. See also Planck units for a system which is mathematically practical, in the sense that ALL of the five major universal constants are defined as "1", but which is not very usable on a daily life since it requires the units themselves to be impractically tiny.--Jayron32 16:13, 4 October 2010 (UTC)

If you are measuring in a way that requires lots of halving and doubling it would be more logical to have a base more easily halved and doubled into whole numbers than base-10. Inches (12) and yards (32) are easily to halve into simple fractions than base-10 SI units. At least, I've always found that to be the case. Somehow it seems easier to quickly grasp what 1/16th is over 0.0625. And five 16ths is obviously 5/16, while 5 * 0.0625 is... um, er... hmm. Pfly (talk) 11:25, 5 October 2010 (UTC)

"Wretched English system"? I think you mean wretched American system, as England has been largley metric for decades. 92.29.115.43 (talk) 18:33, 5 October 2010 (UTC)

But the wretched Americans inherited the wretched system from the wretched English, and give discredit where discredit is due. Edison (talk) 18:56, 5 October 2010 (UTC)

The Americans could have chosen to go metric decades or perhaps even centuries ago, so its their own fault. I recall some planetary probe went wrong as a result. 92.29.127.126 (talk) 19:46, 6 October 2010 (UTC)

HIV infection

Why is it that if an adult gets the saliva of an HIV infected person in his/her mouth by kissing, he/she will most likely not get infected. But if a child drinks breast milk of a mother with HIV, he/she will probably get infected. Doesn't the virus get destroyed in the stomach? —Preceding unsigned comment added by 76.169.33.234 (talk) 02:15, 4 October 2010 (UTC)

There are several factors involved. It is possible for a child to be infected from breast milk, but most maternal infection occurs during childbirth. In any case, the probability of a child being infected by an HIV-positive mother is only about 25%, even with natural childbirth, and cesarian section lowers that figure dramatically. Breast milk may or may not contain more virus than saliva, I don't know, but the length of exposure during breast feeding is far longer than for most kissing. The virus does get destroyed by the stomach – infection in these cases is thought to be through small wounds in the mouth. Physchim62 (talk) 02:43, 4 October 2010 (UTC)

(to the OP)I think you're overstating the risk from breastfeeding: 6 weeks of breastfeeding for children of HIV-positive mothers in Zimbabwe carries about 5-10% risk of infection (PMID 20121424). It is true that breastfeeding is much riskier than kissing, so it's worth discussing, as follows.

Saliva contains very low levels of HIV, when it's present at all: in one study (PMID 12907539) on HIV levels in a variety of fluids taken from people with HIV, only about 5% of parotid saliva specimens contained detectable HIV RNA, and even when detected the mean viral load was only about 200 copies/mL fluid (estimated from figure 1). When one considers the volume of saliva exchanged, we're talking about a very small amount of virus. If we (over-)estimate 10 mL of saliva exchange, that's about 2000 copies of HIV in the 5% of the time that it can be detected (i.e. on average, there would be close to zero per exposure). There are quite a few papers documenting antiviral properties of saliva (e.g. PMID 7615818, PMID 2078420, reviewed in PMID 10401522). Whatever the reason, kissing is considered not to be risky for HIV transmission if blood is not transmitted.

Breast milk contains much more HIV, with levels over a 6-week period in one recent study (PMID 20121424) averaging 1.8 log₁₀ (63 copies/mL). A baby ingests about 100 mL of breast milk in a feeding, which would mean that more than 5000 copies of HIV are ingested per meal. As that report summarizes, there are many things that are not explained about the transmission of HIV by breast milk, including the paradox that exclusive breastfeeding seems to carry a lower risk of HIV trasmission than mixed feeding (breast and bottle feeding). It's easy to make guesses as to why this might be true, but the answer is not known. -- Scray (talk) 03:43, 4 October 2010 (UTC)

So would the small chance of infection from breast milk happen because a cut in the mouth? —Preceding unsigned comment added by 76.169.33.234 (talk) 09:05, 4 October 2010 (UTC)

I was always under the impression that HIV cases in children were mostly caused by crossing of the virus to the baby via the placenta? I'm not sure why breast milk would be any more significant than any other fluid in carrying HIV; assuming no cut, why doesn't the virus just break down in the stomach? Regards, --—Cyclonenim | Chat  10:42, 4 October 2010 (UTC)

If the virus could cross the placenta, infection rates of children would be 100% (or as near as makes no difference), and you wouldn't see an advantage for cesarian sections. Physchim62 (talk) 10:46, 4 October 2010 (UTC)

Fair enough, as I said it was just an impression I was under. Clearly I was mistaken. I'm sure it does cross in certain cases though, right? Regards, --—Cyclonenim | Chat  12:52, 4 October 2010 (UTC)

Yes, HIV is listed in the "other infections" category of the TORCH complex of perinatal infections than sometimes cross the placenta, so it's not 100% sure. However, my impression was that the main route of infection was through abrasion during natural childbirth: you don't need a bleeding cut for the viraus to gain access to the bloodstream. Physchim62 (talk) 13:53, 4 October 2010 (UTC)

Bear in mind that the baby's digestive system is designed to allow intact proteins (antibodies) into the body as a method of passive immunity. To quote from one source, 'At birth gastric pH ranges from 6 - 8 due to residual amniotic fluid in the stomach. (Amniotic fluid is regularly swallowed during intrauterine life.) Gastric pH then falls to a pH of 1.5 to 3 within 24 to 48 hours after birth but during the first week of life returns to neutrality. Gastric pH then decreases gradually to adult values after approximately 2 years of age (range 3-7 yrs). This higher pH which normally occurs during this time is referred to as a "relative achlorhydria".'[2] According to PMID 10099107 the virus does enter via the gastrointestinal tract, though the exact cell type was unknown as of 1999. Due to a lack of inspiration on search terms I haven't tracked down the pH needed to kill HIV, aside from one curious advocate of using lemon as a contraceptive and antimicrobial, who claims lemon pH (which adults but not babies will have in the stomach) kills HIV in two minutes.[3] Wnt (talk) 16:22, 4 October 2010 (UTC)

Pre-positioned nuclear weapons

What is the probability that small, well-hidden nuclear weapons have already been strategically pre-positioned in urban centers around the world by one or more nuclear-weapons-capable nations? WikiDao ☯ (talk) 03:26, 4 October 2010 (UTC)

Resolved

 – thank you for the responses. I'm going to call it "high". WikiDao ☯ (talk) 07:49, 8 October 2010 (UTC)

Collapsed for page readability; click "show" to see.

:Who can say? What possible evidence could there be? Were such a device ever found, would anybody announce it? But I think it's safe to assume "basically zero". — Lomn 03:47, 4 October 2010 (UTC) I'm not asking for a prediction, but for an estimation. On what basis would you expect that probability to be so low? WikiDao ☯ (talk) 03:54, 4 October 2010 (UTC) Because the longer you leave them sitting around, the higher the chance that somebody will find one, and if somebody finds one, there will be hell to pay. They aren't very easy to hide: unless you encase them in massive amounts of lead, the radioactive materials will show up bright and clear on a radiation detector. Looie496 (talk) 04:21, 4 October 2010 (UTC) Sources for likely OGA response? Sources for ease of securely hiding a device that's been well-engineered for its purpose by nations with a nuclear-weapons-capable level of technological sophistication? WikiDao ☯ (talk) 04:38, 4 October 2010 (UTC) I don't have good sources either, but I'll venture to speculate anyway. One thing is that nuclear weapons have a limited shelf life. Thermonuclear ones containing tritium need to have that stuff replenished from time to time. Just plain plutonium, I think, loses some of its power in storage over the years as well. But above that there would be the positioning of the device. As pointed out earlier, it would have to be pretty well hidden. And nuclear weapons are most effective against non-hardened targets, such as cities, when detonated at a considerable altitude above the target. Blowing up a smallish fission bomb in the basement of a Manhattan skyscraper would certainly bring down that building and do a lot of damage, but it wouldn't be quite as spectacular as a good blast at 2,000 feet. I think. But as I said, I can't point to sources, this is all just based on stuff I think I know about nuclear weapons. I'm sure there are a lot of unknown unknowns out there, at least unknown to us civvies.--Rallette (talk) 05:09, 4 October 2010 (UTC) Any bomb that needs tritium needs to have it replaced pretty often. But you could design a bomb that didn't need tritium. Plutonium aging raises the uncertainty of the total yield, but probably not to unacceptable levels. (And you could use HEU, which is not as problematic as plutonium.) As for the effects, it depends on what you are trying to accomplish. If the goal is just "kill enough people to make a point," you can do that pretty easily. A bomb with 100 tons of TNT yield somewhere on Wall Street could probably kill 10,000 people and require billions in cleanup (at least, that's what Ted Taylor was famous for saying). That's not as bad as it would be if it was a megaton nuke put at a desirable altitude, no, but it's pretty bad. --Mr.98 (talk) 12:17, 4 October 2010 (UTC) This looks to me like the Argument from ignorance. Firstly, there is an implied proposition — there might be nuclear weapons placed in urban centers by hostile nations, and they are so well-hidden that no-one living in those urban centers knows they are there. Secondly, when several Users say they think the likelihood is extremely low they are asked to provide the basis on which they expect that likelihood to be low! WikiDao has implied the proposition that there might be nuclear weapons in urban centers, so well-hidden that no-one knows they are there. The principles of logic require that WikiDao must provide some substance to support his proposition. If WikiDao is unable to provide some substance his proposition must be seen to be very weak. Scientific skepticism becomes highly relevant. If other Users are unable, or choose not, to provide something to substantiate their opposition to WikiDao's proposition, that is not evidence in support of the proposition. Despite WikiDao's challenge to us skeptics to provide substantiating information, it is WikiDao who must provide some reason as to why we should even begin contemplating his proposition. Dolphin (t) 05:27, 4 October 2010 (UTC) Dolphin, I am simply wondering if a) it is possible to produce a nuclear weapon capable of being well-placed in a large city and capable of strategic levels of disruption to that city, and 2) whether it would make any sense for anyone to do so if they could. On the basis of information available to you, can you assess the joint probability of those two cases? And from that estimate, if non-zero, and the number of nations for which it would be both possible and advantageous to do such a thing, how likely is it to have been done already? Do I really need to justify my question any further for it to merit a response here at the WP Science Desk...? WikiDao ☯ (talk) 05:52, 4 October 2010 (UTC) Your original question was based on the expression weapons have already been strategically pre-positioned ... and asked for a probability. For reasons I have explained, I consider your request to be illogical. I concede that it is reasonable to ask whether this event could occur in the future, but your original question did not talk about possibilities for the future, it talked about something that has already happened, and you asked for the probability. I'm pleased to see you have transformed your question so that you are now asking about the feasibility of an event occuring in the future. Dolphin (t) 06:16, 4 October 2010 (UTC) In frequentist terms this question does not make sense, but in terms of Bayesian probability, it does. Not that that makes it clear how you'd give a defensible answer. --Trovatore (talk) 06:34, 4 October 2010 (UTC) A reasonable answer would be in terms of how strategically useful such a device would be given how technologically likely it would be (given publicly-available information) for an easily-hidden, affordable, and strategically "effective" device to be developed. I am assuming such an assessment can be roughly made for the present time, without undue regard for the unknown aspects of that possibility pertaining to either past or future technology. It really does not seem to be such a difficult question to answer as responses so far have seemed to try to make it appear to be for some reason. WikiDao ☯ (talk) 07:44, 4 October 2010 (UTC) For aging ("limited shelf-life") issues, see JSR-97-320, January 1998. Assume details of that kind to be well-understood by nations capable of developing and placing such devices in the first place (assuming nations with such technological sophistication exist, of course; I propose this to be a self-evident truth). My point is that it is technologically feasible for such a thing to be done – even if, like all useful nuclear-weapons technology, it also tends to be expensive. Is the skepticism here due to an expectation that such a pre-placement of nuclear devices would not be strategically worth the expense of developing, placing, and maintaining them...? Or that it is simply not possible somehow on technological grounds to do so? WikiDao ☯ (talk) 05:39, 4 October 2010 (UTC) Self-evident, how so? That report, while 12 years old, pretty much concludes that "we" (the U.S.) don't really understand how plutonium ages, although aging of about twenty years did not seem to affect the performance of nuclear weapons. I'm just very skeptical about the strategic value of such a program, as you put it, and not least because of the potential for technical problems, nuclear or otherwise. As the same report notes, the non-nuclear parts of a bomb are at least as complicated as the nuclear ones. Even mothballing a simple truck is actually difficult, especially if you want it to start up at the turn of the key. Plastics age, seals leak, materials react with each other in surprising ways. It is questionable whether you could ever be quite confident that a nuclear weapon will remain workable (and safe!) for a long time without checking. Even then, a bomb hidden in a fixed location would be muffled by the structure that conceals it, and could only ever be used against that target. You could use a huge bomb, but that would make it that much more difficult to get in place and conceal (plus it wouldn't be "small" anymore). Or for some flexibility, you might consider some kind of remote-controlled delivery system, which would add another layer of unreliability. All of this meaning agents would be needed on the spot to install and then maintain it. Human agents with specialized knowledge, operating for a long time in more or less hostile territory, are a scarce resource with potentially better uses, as well as a source of risk, being only human (the successes of Al Qaeda notwithstanding). And last but not least, if you have confidence in your long distance delivery capabilities, then the motivation will be difficult to come up with. To level a city, I'd go for missiles and planes. And for counterforce purposes, well, zero warning time would be great to have, but cannot be achieved in this way. In sum: if you're Russia or China, you don't need it, and if you're North Korea, you probably can't do it. All of which is not to say such a program is impossible; the V-2 had little military value but the Führer apparently just thought it was cool. Now smuggling a couple of suitcase bombs into an enemy country, to be used by agents in time of conflict as the need arises, that might be a workable idea. But what do I know? These are mainly just objections I've come up with when considering the same idea myself some idle afternoon.--Rallette (talk) 07:31, 4 October 2010 (UTC) (Whoops, I misread your "self-evident" statement. Sorry about that.--Rallette (talk) 07:46, 4 October 2010 (UTC)) Those are some good initial thoughts on this, Rallette. ;) Regards, WikiDao ☯ (talk) 07:48, 4 October 2010 (UTC) For the record, my answer (pending further discussion;) is: near 100%. WikiDao ☯ (talk) 07:52, 4 October 2010 (UTC) Effective further discussion that would dissuade me from that view would include explanations as to how: 1) such a thing is either technologically and/or financially implausible and 2) it would not be strategically advantageous for any country that can get past 1) to actually do it. WikiDao ☯ (talk) 08:05, 4 October 2010 (UTC) How the hell did you reach a conclusion of nearly 100% from the above discussion? The probability of nuclear weapons being concealed in cities is not zero, but it's no where near 100% either. Suitcase bombs were designed so that an agent could go and place them at a location and set a timer on them, but this is very different to just putting a bomb somewhere and leaving it for an unspecified period of time. To address your questions, no it's not financially impossible, and no it's not technically impossible. That doesn't provide any evidence for your theory, though. Why put a weapon in a concealed place where it is going to do significantly less damage and be less reliable than conventional 'drop out the sky' or submarine based nuclear weapons? Almost all strategy in the Cold War was based on the U.S. and Russia simultaneously firing nuclear weapons from missiles, not detonating ones in concealed places. That is simply very impractical from a reliability standpoint. I don't know how you think it's a near 100% probability taking this into account. Regards, --—Cyclonenim

Further consideration

For one of the factors in this assessment, let's say there are only five nations at present with the acknowledge-able technological capacity to easily produce enough such weapons to suit their strategic interests: US, Russia, UK, France, and China. And let's say each of these five could produce "many" should doing so indeed suit those interests. So it is coming down to how advantageous this strategy would be for at least those five nations. Does anyone have any sourced indications of how likely it is for that to be advantageous in that way...? WikiDao ☯ (talk) 19:27, 4 October 2010 (UTC)

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:It would be less advantageous to hide a nuke for one of those nations then it would be to use a missile delivery system. Consider the following. If you hide one, you run several risks. Risk of getting caught smuggling it in. Risk of it being found by the government and exposed. Risk of it getting found by criminals and stolen. And weigh those risks against the risk of you keeping it attached to an accurate delivery system in a secure location, always ready to place it anywhere on earth in 20 minutes or less. Add to that, governments do not like one person to control a nuclear device, and that would add a further layer of complexity to the hidden warhead scenario. Because of the balance of these equations (which admittedly are difficult to quantify), I would place the odds of a major warhead producer hiding warheads in the cities of potentially hostile nations at about the same likelihood that the assassination of JFK was a mistake and that Jackie Kennedy was the intended target. Googlemeister (talk) 19:37, 4 October 2010 (UTC) See our Brinkmanship article for a sense of the tolerance for risk in strategic geopolitical affairs. And I am not sure what you believe would actually happen if a device were discovered by a nation (eg. in the basement of some foreign-owned building, like a consulate or embassy or "safe-house"...) or on what basis you believe that would happen. Your point about the need for a variety of fail-safes in the system is a good one, but hardly an insurmountable obstacle given the level of sophistication of the nations currently being considered. And delivery by missile or aircraft has several disadvantages (even just at present, and potentially still more so as time goes on) compared to having nukes already in place. Thank you for your thoughts though, GM :) WikiDao ☯ (talk) 20:18, 4 October 2010 (UTC) Brinkmanship? Try direct act of war. Googlemeister (talk) 20:27, 4 October 2010 (UTC) Not if done subtlety. At least not any more an "act of war" than putting Pershing II's in Europe or any of the other equally dangerous/threatening things that went under the heading of "brinkmanship." --Mr.98 (talk) 21:02, 4 October 2010 (UTC) On the contrary, they are two distinct things. In the Pershing II scenario, you are not placing weapons of mass destruction in the country of your rival, just nearby. In the basement scenario, you have essentially invaded with part of your armed forces (commandos in action if not name), which is about as traditional a casus belli as you can get. Googlemeister (talk) 21:12, 4 October 2010 (UTC) But you can put armed forces in your own embassy, no? Anyway my point is that in real-world terms, it's not clear to me that it would be treated as an act of war. That's the thing about nukes — as Churchill quipped, the worst things get, the better they are. The more real the threat is, the less likely it will lead to actual war. So the theory goes. --Mr.98 (talk) 22:20, 4 October 2010 (UTC) Agree with 98 on that one. :) And military activity in one country by another country without those countries being at war with each other or likely to go to war with each other as a result is hardly uncommon in this day and age, GM, when it suits the acting country's interests to do such a thing. I think there was a question here recently about US military activity inside Pakistani territory, wasn't there? Happens all the time; as would pre-placing nukes, I am saying, by countries who both are capable technologically of doing so and perceive a strategic advantage to themselves in actually doing so. And note that once it gets done, there's self-evidently not a whole lot that can be done about it, is there? ;) WikiDao ☯ (talk) 00:47, 5 October 2010 (UTC) The logic here is rather unusual. What you are telling me is that if China wants to create a very large embassy in DC and maintain an armored division on the grounds that the US would allow that? Absurd. As for US troops violating Pakistan, that only proves my point. They have stated that Pakistani forces would open fire on US troops if they are in Pakistan. I am sure they would be much less happy about the US storing nuclear warheads on their territory. Googlemeister (talk) 13:19, 5 October 2010 (UTC) O... kay. Thank you for your response, "Googlemeister". WikiDao ☯ (talk) 19:31, 5 October 2010 (UTC) Of those you mentioned, only Russia and China would have any real incentive to do this. Both have serious delivery issues with regards to the United States on account of it being so far away, and because US allies are so close to their own borders (in Russia's case), or, as in China's case, the crucial cities are so close to the coasts (and vulnerable to subs). There is really no advantage for the US, UK, or France that I can see. The US would have no reason for this for most of the Cold War. I don't think any power would have any real advantage in fielding this sort of thing today — the nuclear threat from the US is just not very high. --Mr.98 (talk) 20:56, 4 October 2010 (UTC) (edit conflict) Well, there's no need for present purposes to get too probabilistically precise about that last assessment. But I wanted to directly spell out that wikilink above about some of the disadvantages of airborne delivery: "National missile defense": expensive new technology still largely in development. Issues such as that do have an impact on the strategic advantages of pre-placement, don't you agree? WikiDao ☯ (talk) 21:07, 4 October 2010 (UTC) I will grant you, the intercepting systems may make nation states rethink their delivery systems in the future. I would even expect something like this from a non-nation, but at this time, the intercepting systems are not sufficient to intercept most ballistic deliveries in the event of a conflict. Googlemeister (talk) 21:16, 4 October 2010 (UTC) Okay. Re. "non-state": the List of states with nuclear weapons is worth considering in its entirety, but for simplification purposes I would still like to focus for now on only the five nations already being considered. WikiDao ☯ (talk) 21:25, 4 October 2010 (UTC) Sure, that might make a difference in evaluating the advantages, if it got to the stage where it actually seemed workable or reliable to the point that it would actually be able to stop a real attack (which current tech is nowhere near being). There are still considerable disadvantages to pre-placement, of course. --Mr.98 (talk) 22:20, 4 October 2010 (UTC) It would be extremely easy to do and extremely useful under easily forseeable contingencies, though with dire consequences when the action was discovered. It is similar to having stealthy long-term moles in a foreign country with weapons caches, but with a much greater ability to make the host country do what you want. We know that the Soviets buried caches of guns, explosives, and money in the US during the cold war, for instance. The Russians, Israelis, Chinese, British, French, Indians and Pakastanis are known to have nukes, and some administration might think it was a good idea to position nukes in the US to exert leverage in some future situation. Then there is no need to launch missiles or to get airplanes past US air defenses. (Or Indian or Pakistani air defenses for that matter). The best method would be using misdirection, like hiding a Soviet suitcase nuke in a former Soviet-block capitol, or a former tactical US nuke in a US city, or some other country's nuke in a rival country, so that if it were found or detonated there would be confusion. I would give it 75% probability, increasing over time. How many tons of contraband enter the US every year? Why couldn't one 50 kilo package be a nuke? The attacker might set off several in a country as demonstrations, and promise to continue until the country's policy changed in some desired way, when the target country does not know how many there are or what the next target is. It worked nicely against Japan in 1945, when in fact the US did not have a third atomic bomb to drop, and Japan was all set to do house to house fighting at a cost of millions of Japanese lives against a conventional invasion. Edison (talk) 01:34, 5 October 2010 (UTC) Now we're talking! :D Thanks, Edison. WikiDao ☯ (talk) 01:50, 5 October 2010 (UTC) I think a big difference between ordinary contraband and nuclear weapons is by and large if most contraband gets caught it's annoying but often just a cost of doing business for the people involved. To use the most obvious example, illegal drugs. Whether precursors or finished products most of the high up people accept they're going to lose their packages some times. It's potentially bad for the lower down people involved but for the high up people they know a few discoveries aren't going to affect them in the short term (over the long term people the authorities may work their way up the chain using the leverage garned from things like failed smuggling attempts), they're naturally insulated from that sort of thing. In fact particular with precursors that are cheaply and easily available in other countries a scatter gun approach is sometimes the strategy adopted [4]. This is vastly difference for smuggling nukes since one discovery is enough to cause major problems when it comes to state actors. I'm not saying it will lead to war, but I definitely think the willingness of state actors to risk discovery of nuclear weapons they sent to another country is much, much less then the willigness of most smugglers to risk discovery of whatever it is they happened to be smuggling. And frankly many smugglers (particularly the lower down people and lone gun types) are generally a bit dumb anyway and don't really appreciate the risk to them. Nil Einne (talk) 06:23, 5 October 2010 (UTC) Nil. Ease-of-delivery is certainly a factor in the probability concerning which I am asking this question. So: could you give a rough estimate for what you believe the probability is that both 1) US, Russia, UK, France, and China would have any difficulty at all delivering and pre-placing undetected a suitable nuclear device into any other state (or even "non-state") and 2) would be tried in the court of world-opinion if they were somehow "caught" and would be made by the world to feel ashamed and repentant for that action if they were? And even if that probability is high (please try to reference your argument well if that is what you believe), would that risk really be much of an effective deterrent to any of those five states if they thought it was in their strategic interests to make the attempt anyway? WikiDao ☯ (talk) 18:05, 5 October 2010 (UTC) But the key thing with the nukes is that once they are in place, it becomes straight-up deterrence. Nasty brinkmanship, to be sure, but I'm not sure I see the difference between that and the Pershing II situation. (For those who are not aware: Pershing II missiles were intermediate range missiles that the US put in Europe, aimed at the USSR. They were a "decapitation" weapon that would totally obliterate the Soviet high command in a matter of minutes. They gave the Soviets a response time to an attack that could be counted in seconds. They made the Soviets very unhappy and very jittery. It was like having a nuclear gun pointed at their head that they would have almost no time to respond to. That's the comparison I'm making to the nuke-in-the-attic = no response time, no defense.) I don't think they'd need to use smugglers to get a nuke in — you could do it through diplomatic pouch if the goal was to keep it in the embassy. The US was actually very afraid of this possibility in the 1950s. --Mr.98 (talk) 12:12, 5 October 2010 (UTC) Small point — the US would have had another bomb at the end of the month in August 1945. They would have had roughly a bomb per month after that as well. If the war had dragged on, they would have used them. It was a short term bluff but not a long term one. --Mr.98 (talk) 12:12, 5 October 2010 (UTC) I just recall reading that after dropping nuke number 2 on Japan, Truman called in General Grove and said "I want to know how many more a bombs we have. Don't say it! Just write it on this paper (knowing that various organizations foreign and domestic might have bugged the Oval Office" whereupon Grove drew a circle on the paper. Ideally, Truman would then have said "WOW! That many?" (again for the benefit of any hidden listeners). Not knowing how many more nukes were going to be detonated, or when, or where would induce national terror on a scale which would make it hard to ignore the demands made by the bombers, with cities depopulated by evacuation and the economy at a standstill. Edison (talk) 18:52, 5 October 2010 (UTC) Again, it's true that they had none right after Nagasaki, but they had a whole bomb production system. Groves estimated they'd have another ready to go on August 17 or so. I don't know the Groves/Truman anecdote but I do know a Truman/David Lilienthal anecdote that is similar (in January 1947, Lilienthal found that the US had zero assembled bombs in its inventory, just some cores and parts — Truman was rather shocked). Anyway, I'm a little dubious at the "total terror" situation from nuclear blackmail. I've never seen any threat that actually resulted in that level of people going bananas over it. Maybe this would be different if a few went off first. But I don't know. My general reading of history is that people are more resilient in real life than they are in the movies and tend not to totally panic in the way you describe. They more often dig in and become fatalistic. --Mr.98 (talk) 01:37, 6 October 2010 (UTC) The Japanese, poised to spend a million civilian lives killing invaders in hand to hand fighting were not "resilient" after Hiroshima and Nagasaki. The US, or any other country, would not be "resilieant" after several cities had been annihilated by atomic bombs. Would you still commute to work in Chicago after New York and LA had been destroyed, when your office building was likely to be smashed by the next bomb? This is not like "keeping a stiff upper lip" and enduring the London blitz, where a miss was as good as a mile. Edison (talk) 05:03, 6 October 2010 (UTC)

Relevance

"Your tax dollars hard at work."

What real-world relevance might there be of a well-reasoned, reliable answer to this question? (Which, again, is: what is the probability that at least one nuclear-weapons capable state has already pre-placed nuclear weapons in strategic sites around the world?)
One such issue of relevance has already been mentioned: what would be the impact of the value of this probability on a cost-benefit analysis of an (expensive!) missile defense program...? WikiDao ☯ (talk) 22:48, 5 October 2010 (UTC)

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::Then, we should refer the questioner to a reliable source, such as the Nuclear Posture Review. The Defense Department NPR report is available to the public, and provides "a legislatively-mandated review that establishes U.S. nuclear policy, strategy, capabilities and force posture for the next five to ten years." Part of this report includes a cost/benefit analysis that justifies the official policy of the President of the United States with respect to nuclear security. Nimur (talk) 00:32, 6 October 2010 (UTC) Excellent source for this, Nimur! :) Thank you! I was asking (immediately above) about the impact of a good value for the probability of pre-placement on a missile-defense program cost-benefit analysis – which per your ref has been so clearly well-conducted, and then made available to us, by our leaders! (BTW: I think this consideration should have a negligible long-term effect on that analysis (missiles are always going to be a problem, whatever else might be a problem, too..), but may nevertheless cause some short-term complications in it (eg. Russia: "You put up the Shield, we string your cities with nukes like Easter eggs. :] ")). I wonder if there is any other real-world relevance to this consideration (besides re. missile defense strategy/funding)...? WikiDao ☯ (talk) 00:47, 6 October 2010 (UTC) There would be lots of real-world relevance, and that's why this is the kind of thing that think-tankers spin their wheels over (along with "how easy would it be for a terrorist to get a bomb?" or "how reliable is a missile defense system?" or "why do some states help other states get the bomb?"). I am sure that someone has covered this in a political science paper or thesis on deterrence. I'm just not sure what it would be called in the official jargon. Anyway, the real-world relevance includes the following measures (an incomplete list, I am sure): Defensive (should you bother?) Offensive (should you put your own nukes in your own overseas embassies?) Security (should you screen things arriving by diplomatic pouch for radioactivity? should you limit the size/weight of diplomatic pouch?) Counterintelligence (should you try to get a spy into the embassy basement to check?) Communication (should you make sure you have a good hotline to the enemy of choice, to make sure they don't ever get desperate?) Diplomatic (could you convince another power not to put them in their embassies?) And so on. I don't think there would be just one option — it's not like if you found it likely that they were there, that you'd have to necessarily abandon all missile defenses. It would be lousy to lose DC and New York, but that's still better than losing the entire eastern seaboard. If you believe that there are "better" and "worse" nuclear exchange outcomes (which some people do, some people don't), then that might not change a thing with regards to defense. Just as an aside, I would caution about using the Nuclear Posture Review as a "reliable source" for this kind of question. It's a political document that reflects current administration defense priorities and justifies them. It is not independently created. Thus the Bush NPRs and the Obama NPR are totally different in their assessments and conclusions. It's a policy document, not a piece of critical analysis. Which is not to say it is bad or dumb or anything. But it's not neutral in any sense. The NPR reliably tells you about the nuclear priorities of the administration that issued it, but that's it. --Mr.98 (talk) 01:47, 6 October 2010 (UTC) Certainly agree with that last bit -- but still just glad something got cited at all! :) It's probably not going to be permissible to take this too far into think-tank-style banter, so I want to avoid seeming to do that and am still mostly just waiting for some further response to the original question – in terms of an estimate of probability. But: I was wondering more about real-world strategic policy issues on which this question may have bearing. Some of the more interesting aspects there, though, have to do with the "unacknowledged" nuclear states. Like Israel, for example. And I do not think there is any reason to assume that any one of the five declared states would require diplomatic pouches to transport such a device in, nor an embassy to hide it in. WikiDao ☯ (talk) 02:23, 6 October 2010 (UTC) Russia acknowledged after the end of the USSR that the KGB had buried caches in the US containing explosives, guns, and money. Were these caches brought in via diplomatic pouch, or simply smuggled like dope? I recall that one was buried in the backyard of a home in Minnesota. A battery had to be connected to terminal points to operate a solenoid so that the cache did not explode when opened. All pretty cool in a James Bond sense. Also, see [5] US House Armed Services Committee testimony from 1999, for info about Soviet weapons caches in western countries. Stanislav Lunev, former Colonel in Russian military intelligence, testified before the US Congress in 1998 that "man-portable nuclear weapons may already be located in the United States." Alexander Lebed, former Secretary of the Russian Security Council, testified to Congress in 1997 that "dozens of such weapons were unaccounted for." I would raise my estimate from 75% to 90%. Edison (talk) 04:46, 6 October 2010 (UTC) Thank you, Edison. "90%" may be sufficient for me here, too. I will wait before stamping the question "Resolved" though to see if any other well-reasoned numbers come along at all. :) Regards, WikiDao ☯ (talk) 17:08, 6 October 2010 (UTC) I just want to note that the arms control people have a healthy degree of skepticism about the Lunev testimony. It's not clear he was speaking from personal knowledge. Military guys (U.S. and Russian alike) are prone to all sorts of crazy speculation that gets taken as gospel because of their positions, though they may not know anything more than the man on the street. I would still have a low estimate. I think the likelihood of any state other than Russia having done this is even lower. --Mr.98 (talk) 21:59, 6 October 2010 (UTC) I actually saw this earlier but forgot to mention. Suitcase nuke#Russian suitcase nukes. In particular it's notable none of the suitcase nukes were ever found. Nil Einne (talk) 04:52, 7 October 2010 (UTC)

What is in this picture of Mars?

In this picture of Mars, what are the things in the foreground that look like bricks? Part of the probe?? Bubba73 ^{You talkin' to me?} 04:09, 4 October 2010 (UTC)

Look like solar panels to me. So, yes, part of the probe. Dismas|^(talk) 04:13, 4 October 2010 (UTC)

Yep, see this image from the Opportunity rover article. Dismas|^(talk) 04:16, 4 October 2010 (UTC)

Resolved

thanks Bubba73 ^{You talkin' to me?} 04:44, 4 October 2010 (UTC)

Also, note that the image is distorted from its "true" shape because it is a stitched panorama. We also have a section on panorama stitch projection geometry. Because the spacecraft's frame is at the bottom portion of the image and is in the near field of the camera, it suffers from severe geometric distortion when merged to a single panorama image. Nimur (talk) 19:55, 4 October 2010 (UTC)

Jellyfish - bubbles in the top part

The other day I got to see some jellyfish up close. They had some air bubbles in their top part. Why is this? Do they take in some air to adjust some buoyancy? Bubba73 ^{You talkin' to me?} 05:27, 4 October 2010 (UTC)

Are you sure it was air? Ariel. (talk) 08:11, 4 October 2010 (UTC)

It sure looked like bubbles of some sort of gas. I got a good look, but I didn't have my camera. Bubba73 ^{You talkin' to me?} 14:36, 4 October 2010 (UTC)

I saw bubbles in a dead jellyfish on the beach, and assumed it to be outgassing from decay. --Sean 14:39, 4 October 2010 (UTC)

These were alive. There is a "CoastFest" here each year, and they had them. If they have them again next year maybe I can get a photo. Bubba73 ^{You talkin' to me?} 14:45, 4 October 2010 (UTC)

Here is an interesting blurb about Jellyfish Lake: "SCUBA is prohibited because the air bubbles exhaled by divers can become trapped in tissue pockets of the jellyfish, air-lifting them to and pinning them against the surface, until the trapped bubbles eventually force their way through the delicate tissue, leaving a nasty wound." --Sean 16:36, 4 October 2010 (UTC)

Any jellyfish on the beach comes up through the surf... Wnt (talk) 17:24, 4 October 2010 (UTC)

These jellyfish were captured the day before, so perhaps they were out of the air long enough to get some of it in. Still, I would like to know more. Bubba73 ^{You talkin' to me?} 18:38, 4 October 2010 (UTC)

Was the jelly fish anything like the one seen in the article Portuguese Man o' War? The bubble is their for flotation. 67.78.137.62 (talk) 18:45, 4 October 2010 (UTC)

No, they were much smaller and didn't have the tentacles, more like File:Moon jelly - adult (rev2).jpg and File:Palau stingless jellyfish.jpg. But if that one has bubbles, then maybe these do too. Bubba73 ^{You talkin' to me?} 18:56, 4 October 2010 (UTC)

Is toxoplasmosis a cause for discrimination?

Today for some reason I decided to invent a new kind of discrimination. According to one study, "latent" toxoplasmosis infection is associated with a 2.5-fold increased risk of traffic accidents[6] - a bit less than the 3.2-fold increased risk for a blood alcohol level of 0.08.[7] As detailed in the article, infection has been tentatively blamed for various psychological situations.

Now one of the most bizarre forms of discrimination in the world occurs in Japan (see Blood types in Japanese culture), where type A is dubbed "fastidious" and type B "wild" etc. Now one study put the toxoplasmosis exposure rate there in 1987 at 28% in males, 16% in females, associated with consumption of raw meat.[8] Relevance? Well, there are reports of blood type B being associated with toxoplasmosis infection [9]; we also have some references to Rh negative or to a lesser degree Rh homozygous positive being more vulnerable to effects on reaction time (see Rh blood group system). So perhaps there's actually a certain grain of truth to this preposterous pseudo-science, though it's not exactly a proved point.

The meat of the matter is really, what is the ethical thing to do? The first publication talks about a million people dying in traffic accidents because of toxoplasmosis infection. Can you justify discrimination against them? Do you talk about increasing the role of treatment, if treatment helps? Is it a public health issue or a private matter? Then there is the effect on pregnancy. And despite decades of teaching that people with HIV aren't dangerous, some of them are infected with high titers of this... there's a can of worms for you. Anyway, I thought I'd throw this up for discussion and see what comes out. Wnt (talk) 07:51, 4 October 2010 (UTC)

In the intro at the top it says:The reference desk does not answer requests for opinions or predictions about future events. Do not start a debate; please seek an internet forum instead.--Aspro (talk) 09:32, 4 October 2010 (UTC)

hmmm, I was thinking of this more as an ethics question. Wnt (talk) 16:01, 4 October 2010 (UTC)

Fascinating tidbit on toxoplasmosis and car accidents. Is it ethical for insurance companies to charge more to insure 16 year old males than 40 year old females? Your toxo example just seems like a specific case, nothing makes it much different than discrimination based on diabetes, heart disease, etc. The public health / private concern issue interesting, but it extends to much more than just toxo status.SemanticMantis (talk) 18:47, 4 October 2010 (UTC)

Dissimilarities between cell lines and genome databases

I'm just wondering whether there is a risk, when planning genetic experiments based on information gained from genomic databases, that the sequence in your particular cell-line(s) or animal strains varies from the sequence in the database. Is it not prudent to sequence your cell-lines or animals for the region of interest first? I think it is but don't want to risk making a tit of myself by suggesting it to my supervisor if I'm wrong. --129.215.5.255 (talk) 11:09, 4 October 2010 (UTC)

It depends entirely on what experiment you are doing. If you are working with human cells, you should assume that your cell line of interest will not be identical to the "reference genome sequence" (which is really just a patchwork of several different individuals). However, that may not matter at all. If you are working with an inbred mouse strain, there may be slight differences in your particular sub-line of the inbred strain, but chances are it will be exceedingly close to the reference genome for that strain, since by definition mice from an inbred strain are homozygous at every position of the genome and identical to each other. We might be able to give a more specific answer if we know the specifics of your experimental set-up. --- Medical geneticist (talk) 12:26, 4 October 2010 (UTC)

Disrupting a gene by inserting a marker - how to express the marker?

If you disrupt a gene by inserting another gene into it and want to use the inserted gene as a marker for the disruption of the original endogenous gene, you could try an IRES. I understand that idea reasonably well. What I don't understand quite so well is the idea of using "splice acceptor" sites, either side of the inserted gene. Would they not just lead to the splicing-out of your marker message, stopping it from being expressed as protein and rendering it useless? Or is the idea that the original gene's message is spliced out, leaving the marker's message to be translated? But this would only work if the endogenous gene had corresponding splice acceptor and donator sites, right? If the "endogenous" gene was actually a stably-inserted GFP gene, it wouldn't have any such sites, making the strategy flawed, right? 129.215.47.59 (talk) 13:45, 4 October 2010 (UTC)

We'd need more detail about your construct and target. From the talk of IRES and splice acceptors I assume you're describing a more or less random scheme for inserting the marker rather than a knockout by homologous recombination. So the construct may be designed to work under a variety of contingencies, with some features unnecessary in some situations. If it lands 5' to the coding sequence, you don't need an IRES and a 5' splice acceptor should be ignored, and translation begins with your marker. If it lands in an exon midway in the gene, it needs stop codons and then an IRES to (partially) knock out the gene and express the marker, but it doesn't need a 5' splice acceptor. If it lands in an intron midway in the gene, it needs a strong splice acceptor to hopefully divert the mRNA into your construct, then it needs a stop codon, then it needs an IRES. If it lands in a 5' intron, it needs a strong splice acceptor, but the IRES isn't necessary because it's the first methionine the ribosome sees. If I understand you right, that is... Wnt (talk) 16:41, 4 October 2010 (UTC)

Sorry for not specifying, but the idea was indeed to use homologous recombination, so the location of the disruption would be controlled. The target gene is GFP which was inserted earlier so there are no introns. Doesn't a splice acceptor require a splice donor to function? 178.98.12.16 (talk) 19:12, 4 October 2010 (UTC)

I'd assume so.... though there could easily be something I didn't think of. For example, there are genes contained entirely within other genes, and perhaps the right splice acceptor could work with a surrounding functional gene. I have to say, I'm surprised to hear of someone going through all the trouble of a knockout in order to disrupt a GFP transgene — so surprised I could be way off base here. Wnt (talk) 02:19, 5 October 2010 (UTC)

Six volt automotive systems

Do we not have an article on the history of automotive electrical systems? I want to know why six volts used to be the standard and why things got changed to twelve. Also why the systems went from positive ground to negative. 155.42.86.171 (talk) 14:36, 4 October 2010 (UTC)

Nothing in car battery, starter motor, or any "auto* elec*" article:( DMacks (talk) 14:40, 4 October 2010 (UTC)

Our automotive battery article says: "In the past some cars had 'positive ground'. Such vehicles were found to suffer worse body corrosion and, sometimes, blocked radiators due to deposition of metal sludge.", but with no citation. I don't know about the 6V vs. 12V question. Bigger is better? --Sean 14:42, 4 October 2010 (UTC)

That is a bit of an oversight. Cars with 6 volt do get passing mentioned in the Jump start (vehicle). I don't know of any cars built after the war that still had six volts but I dare say there may have been some Soviet and Asian made cars still being built. Its asking a bit much for an electic 6 volt starter motor to turn automobile engines as they got larger in size and many budget cars did not have starter motors at all. The amount of copper needed for the leads and windings would have also added to the overall cost. Old aircraft had magnetos for energising their ignition systems and hand swung starting only, so there is no reason why they did not have 6 volts as well..--Aspro (talk) 17:54, 4 October 2010 (UTC)

Didn't some volvos have 24-volt electrics? -- Q Chris (talk) 14:59, 4 October 2010 (UTC)

I suspect that in the early days of motor vehicles with small engines (by modern standards) the optimum was the 6V battery and 6V generator (or dynamo). With the progression to larger engines, the advent of diodes for current rectification and therefore use of alternators rather than generators, the optimum was a larger 12V battery (twice as many cells as a 6V) and 12V alternators and starter motors. (Alternators are more robust than generators with their commutator systems, so alternators can turn at faster speeds than generators, producing higher output voltage without the need for more copper.)

The Volkswagen Beetle was manufactured with the 6V electrical system until about the early 1970s. These days, many vehicles with even larger engines, such as trucks, have 24V systems reinforcing the notion that the heavier the engine and the greater the demand for electrical services such as headlights, the more the optimum system progresses towards higher voltage. Dolphin (t) 21:54, 4 October 2010 (UTC)

I actually owned a 6V Volkswagen back in the 1970s. For whatever reason, it was quite easy to run down the battery, especially in cold weather, and I developed a habit of parking on hills whenever I had the chance. Looie496 (talk) 22:21, 4 October 2010 (UTC)

A 6 volt battery was adequate to crank the starter for a small engine and to run the headlights and taillight. A 6 volt battery was basically cheaper to manufacture because it only needed three (versus six) lead acid cells. Later batteries also had to run a fan for the heater or air conditioner and more lights, as well as a loud ghetto-blasting sound system. Edison (talk) 01:29, 5 October 2010 (UTC)

A number of us have written about smaller and larger engines. I suspect that compression ratio is more significant than engine power. Older engines operated on low-octane fuel. They had low compression ratio engines, some even with a hand crank for manual starting when things got tough — great if there isn't a convenient hill around. Modern engines use higher octane fuel and have higher compression ratios requiring more cranking effort to start. Dolphin (t) 01:41, 5 October 2010 (UTC)

Compression ratio and age wasn't the factor in the UK. Insurance and road tax and was based on cubic capacity and rated horse power. Therefore, cheap Fords and Morris's used 'Regular' grade for their low compression, low power engines. Mid price range cars used 'Premium' grade and little sports cars with short stroke engines, used 'Super' grade for their higher compression. A Tourer on the other hand, might look sporty but tended to have long stroke, mid compression engines, so that they just ate up the miles effortlessly, hence the name, because one would buy one for touring. All cars and lorries back then, had starting handles, even Rolls Royce. Although it does gets harder as the ratio goes up, the overriding reason for introduction of electric starters in cars was for pure convenience.--Aspro (talk) 18:26, 5 October 2010 (UTC)

I remember the 6-volt VW. In the early 70s I was jumping one off with my 12-volt Pontiac. I didn't know about the 6V. I clamped down the jumper cables, and smoke started coming out! My car seemed to have electical problems after that. Bubba73 ^{You talkin' to me?} 01:46, 5 October 2010 (UTC)

calculating odds

Scientifically, what are the odds that Apple's touch devices, like the iPhone, iPod touch, and iPad, are just hoaxes and do not exist in any working form in the supposed form factor and with the supposed method of interaction? (That any photo or video of someone using one must be computer generated, or photo/video edited, or really just taken of someone pretending to use a simple plastic prop like an actor on the set of star trek in the nineties?)93.186.31.238 (talk) 15:02, 4 October 2010 (UTC)

The odds are greater than 59million to 1 against for the iPhone alone. There are about 59million iPhones identified as being sold. So, at least one person touched the iPhone and was willing to pay for it (so it must be real). Then, you have one guy who claims (without having first-hand knowledge of the device) that it is not real. So, the claim is that each of those 59million sales is a hoax and all of the millions of people involved in purchasing, setting up, and using the iPhone are part of the hoax. Not only part of it, but they are spending their own money to become part of the hoax. Further, not a single person has exposed the hoax. -- kainaw™ 15:19, 4 October 2010 (UTC)

There wouldn't need to be 59million plants. I doubt anyone is going around counting iPhone users. APL (talk) 15:49, 4 October 2010 (UTC)

You might as well assert that reality is all a dream and we're all figments of your imagination. There's no way to calculate "odds" on something like that. Either the entire world as you know it is a big lie for really no purpose other than to deceive you (because presumably everyone who owns these things has to be in on the hoax), or it's not a hoax. --Mr.98 (talk) 15:43, 4 October 2010 (UTC)

You could easily verify the reality of the iPhone products by walking into your local Apple store and asking if you could try one. (I've seen several of them myself, but, of course, I could be lying.)

Until you attempt that experiment, I'm not sure how the odds would be calculated. There's far too many unknown factors. (How much would it cost to hire large numbers of fake users, reviewers, advertising, etc? What is the purpose of the deception? How much is Apple willing to invest? How likely are other groups (Like Consumer Reports, for example) to go along with the hoax?) There's no obvious way to calculate any of these factors.

In a situation like this, a scientist wouldn't really bother with probability, he would concern himself with how to make an experiment that tests the hypothesis. If the scientist goes to the Apple store and is successfully able to purchase a real working iPad, well, then the theory is disproved. Ipads are real.

It becomes far more interesting if the scientist goes to the apple store and it's been closed for some reason, then he drives to the next closest apple store, and that's also mysteriously closed! Now the scientist has some evidence. He doesn't have proof that Apple is a hoax, but he has a weird anomaly. He could figure out the odds that the first two stores he tests are closed by coincidence. Then he could use probability theory to determine the odds that Apple stores are intentionally being closed for some mysterious reason.

That's still a long way off from answering your question, of course. APL (talk) 15:49, 4 October 2010 (UTC)

P.S. I like to imagine that our hypothetical scientist would perform his "Going to the Apple Store to buy an iPad" experiment while wearing a lab coat and safety goggles. APL (talk) 15:52, 4 October 2010 (UTC)

S/he would have to complete a 14-page research ethics approval form first.Itsmejudith (talk) 16:01, 4 October 2010 (UTC)

Am I the only one to find the question funny given who owns the IP the OP is using? Nil Einne (talk) 16:31, 4 October 2010 (UTC)

HAHA! That is hilarious. APL (talk) 16:42, 4 October 2010 (UTC)

I think the concept of "odds" does not exist for this question. Odds applies to random events, an iPhone existing, or not existing is not a random event. Ariel. (talk) 19:16, 4 October 2010 (UTC)

According to Bayesian probability, random just means unknown. It's not as if all the probability laws wouldn't work in a chaotic but deterministic universe. As for figuring it out, I figure the most likely explanation other than those products existing is you hallucinating. I don't know what the probability of that is offhand, and there's always the chance that you just hallucinated the evidence that hallucination is rare, which wouldn't be all that unlikely if hallucination wasn't all that unlikely. — DanielLC 23:28, 4 October 2010 (UTC)

I believe (INAStatistician) that it's meaningless to calculate odds without some set of underlying assumptions (then you add in your defined unknowns). Given the depth of a conspiracy required to create the illusion of iP{hone,ad,od}s existing, there's not a whole lot you can rely on if they don't. We're brains in vats overseen by reptilian humanoids which were created by HAARP? Sure, we can throw that in. Paul (Stansifer) 23:56, 4 October 2010 (UTC)

(edit conflict) Apparently, there is maybe about a 1/3 chance of something like that being the case, Paul. Apologies for trotting this paper out again for a third time around here now, but see [10]. WikiDao ☯ (talk) 02:25, 5 October 2010 (UTC)

I skimmed the original paper, and I didn't see the wild claim about 33% probability. However, in the summary published in New Scientist he says "...we don’t have much specific information to tell us which of the three propositions might be true. In this situation, it might be reasonable to distribute our credence roughly evenly between them.", which totally bogus. To see why, observe that you can use this principle to convince Bostrom of any probability. For example, if you break up the "humanity goes extinct" choice into "humanity goes extinct on a Monday", "humanity goes extinct on a Tuesday", and so on, and ask him to choose, he'll say now that there's a 7/9ths probability of humanity going extinct on some day of the week, and 1/9th for each of the other possibilities. Which is silly, since we know it The Hitchhiker's Guide to the Galaxy. The trouble is that you can't use probability to turn a lack of information into a number. Paul (Stansifer) 18:56, 6 October 2010 (UTC)

Indeed. It is clear that the author of that paper is speculating odds, and not calculating odds. I suspect he is overly-trained in philosophical rumination and under-trained in the hard quantitative sciences. When a chemist or physicist lays down statistical predictions, they do so for specifically controlled circumstances, not any old thing that pops into their head. Nimur (talk) 21:08, 6 October 2010 (UTC)

Yes, by "1/3" I was referring to the last lines of the paper,

"In the dark forest of our current ignorance, it seems sensible to apportion one's credence roughly evenly between (1),(2), and (3)."

and then,

"Unless we are now living in a simulation, our descendants will almost certainly never run an ancestor-simulation"

which is also interesting.

Bostrom seems too experienced a philosopher to be easily fooled by the old "surprise test next week" trick (he's sure to have read W. V. Quine, of course;). I'll give some thought to your point when I get a chance, though, and perhaps respond more specifically. The paper is worth considering more carefully in the meantime, though. WikiDao ☯ (talk) 19:39, 6 October 2010 (UTC)

If you're a Bayesian statistician, then you need to assign some sort of Prior probability before you can do a study to better refine your probability. I suppose you could look at how many other, similar electronic devices have turned out to be complete hoaxes. I'm not sure what sort of data you would collect to refine your distribution though... Maybe go to an Apple store, as APL suggested. I Am Not A Statistition either, but it does bring up some interesting statistical points. How is it appropriate to come up with prior probabilities? Is it appropriate at all to try to assign prior probabilities in all cases? These are questions that are routinely debated in the statistics departments of major universities, and while this question is trivial (in my opinion), it does provoke deeper thought about the proper way to do statistics. Buddy431 (talk) 02:23, 5 October 2010 (UTC)

Toy shops sell toy imitation phones that look real at first sight. That means there is a finite probability that a phone that you see someone holding is a fake. The Apple devices mentioned can go wrong and not be worth repairing so there is a also a finite probability of encountering one that is no better than a hoax. Where is your proof that Star Trek is not real and just a conspiracy of actors with plastic props? Cuddlyable3 (talk) 20:28, 6 October 2010 (UTC)

Soil PH 8.3

my soil contains a ph of 8.3 .which plant is suitable to grow in my soil? —Preceding unsigned comment added by 117.254.150.111 (talk) 15:44, 4 October 2010 (UTC)

It contains a ph? Why don't you just remove the ph? :) 129.215.5.255 (talk) 15:47, 4 October 2010 (UTC)

Please don't make fun of posters' grammar. First, many posters are not native English speakers, and second, it's rude regardless. APL (talk) 15:59, 4 October 2010 (UTC)

(edit conflict)Hey 129.215: There's no need to berate people for their grammar errors. To 117.254: The articles Soil pH and Alkali soils have some background. Depending on where you live, large "home centers" or "gardening centers" like Home Depot often sell treatments to correct soil pH problems. --Jayron32 16:01, 4 October 2010 (UTC)

It would help to know were you live. If the pH is high because you live in the desert will require different plants to if you live on chalky soil in some cold climate. 8.3 is also a bit high, could it be due to ash or some other contaminate being disposed there?--Aspro (talk) 16:20, 4 October 2010 (UTC)

I'll berate Jayron32's grammar by saying that berate is not the most accurate word when a little emoticon was added to the comment. --Chemicalinterest (talk) 16:51, 4 October 2010 (UTC)

High ph means that plants struggle to absorb essential elements such as iron, manganese, zinc and phosphorus. You are likely to get yellowing of the leaves of most plants. Adding aluminum sulphate or peat moss or manure or just plain sulphur is often recommended to lower the ph. Vegetables such as spinach, asparagus, carrots, cabbage and celery can tolerate ph up to 8 or so. Meadow flowers can often cope with high ph, but I don't know of many garden plants that can cope with 8.3. Is all of your soil such a high ph? Has someone been dumping lime on the soil? Dbfirs 17:00, 4 October 2010 (UTC)

For what it's worth, the OP's IP number geo-locates to New Delhi. Where about in India are you? Do you want native plants? Do you get bad monsoons? CS Miller (talk) 18:27, 4 October 2010 (UTC)

Then it is probably just something known a canker (Kanker) which frequently forms naturally in hot dry climates (well, hotter than the one I live in) which lie in a alkaline soil area. The colder Chilean potash mines might be an exception... but then again, they were laid down along time ago and they might have been nearer to the equator then. Yeah, forget I mentioned that. Think that the inquirer would be better off seeking out a New Delhi horticultural organisation for a list of plants (herbs/flowers/food crops/fruit trees etc.) that favours local conditions. Also, green manure, dug back in, will ferment and so produce CO2 that will help to acidify the soil and improve its structure, enabling a greater range of horticultural options to choose from. Our article Alkali soils has a fuller explanation. A local New Delhi organization will be able to provide much better advice that we can here, because the OP is living in a small local area of alkaline soil were he would benefit more from local know-how.--Aspro (talk) 21:22, 4 October 2010 (UTC)

I have no reason to question the OP:s ph-value but be aware that some cheep ph-meters are rather inacurate. I has one that can be of by more than one unit. --Gr8xoz (talk) 21:40, 4 October 2010 (UTC)

Stinky refrigerator

Our small storage refrigerator broke recently and some meat inside it rotted. Now the whole thing stinks. What is the best way to deodorize the refrigerator compartment? Note: There was only meat, milk, and water jugs in the refrigerator. There was no food that needed to be saved. Thanks, Chemicalinterest (talk) 15:46, 4 October 2010 (UTC)

I've noticed sliced lemon used to deodorise a fridge. Otherwise, you can get a spray product that is a combination of Flash(tm) and Febreeze(tm) which might do the trick. --129.215.5.255 (talk) 15:49, 4 October 2010 (UTC)

Two common substances to deodorize a fridge are activated charcoal and baking soda. There are a multitude of little containers which you can hang in the fridge to get the smell out. Or, you can just spread some baking soda on a dish and see if that does the trick. It may take a few days to see if it works, depending on the severity of the stench. --Jayron32 15:58, 4 October 2010 (UTC)

(editconflict) Bicarbonate of soda is traditionally used to clean fridges and I think it could deodorise it to an extent. Itsmejudith (talk) 15:59, 4 October 2010 (UTC)

Check under the fridge as well (in the drain pan). It is possible that some stinkyness got in there. -- kainaw™ 16:11, 4 October 2010 (UTC)

Peroxide bleach for the first thorough clean. Plenty of baking soda (half a cup) and water for the next wash. Air it, to let the odours disperse. Don't expect miracles over just one night. Put a bowl of backing soda and water inside to continue to absorbers the smell. Finally get one of the charcoal fridge absorbers.--Aspro (talk) 16:14, 4 October 2010 (UTC)

My experience is that the metal in the fridge is quite easy to deodorize; any of the washing mechanisms noted above will work. The problems lie in the plastic bit: racks, bins and door liners. If the smell persists beyond all your best effort, you might need to replace these elements. Bielle (talk) 16:21, 4 October 2010 (UTC)

I used hypochlorite bleach and will see whether that works. We did drain the drainpan. It is mostly plastic. Thanks for the suggestions. --Chemicalinterest (talk) 16:50, 4 October 2010 (UTC)

There was a similar question here: Wikipedia:Reference desk/Archives/Science/2010 June 28#Getting rid of freezer odour. Ariel. (talk) 20:05, 4 October 2010 (UTC)

Vanilla essence has worked for me in the past. There are even commercially available products containing it if you want to spend the money, but raiding your pantry is cheaper. Just put some on a damp cloth and wipe all the surfaces. Certainly a lot more food friendly than hypochlorite! Mattopaedia ^{Say G'Day!} 10:36, 5 October 2010 (UTC)

Storing Cr2032 Batteries

I have a bunch of lithium cr2032 Button cell batteries for a project, they are in packaging that is overly secure, a pain in the ass to get open, and then not at all secure once opened. I want to repackage them so that they are easier to access. My worry is that I should not dump them all into a tupperware container or a plastic bag, as they might overheat when the terminals are touching in a big group. Is this a valid fear? Any ideas on an easy way to keep 300 of them separate? Beach drifter (talk) 18:34, 4 October 2010 (UTC)

Just curious. What use do you have for 300 Cr2032 batteries.(I just use a good pair of beefy scissors)--Aspro (talk) 18:48, 4 October 2010 (UTC)

This + This. Beach drifter (talk) 19:03, 4 October 2010 (UTC)

Parafilm? Wnt (talk) 18:49, 4 October 2010 (UTC)

Yes it's a valid fear. Take a long piece of tape and stick each one on it. Stick it negative side (the "inner" metal side) down. I would use packing tape and do two rows. Regular scotch tape will probably not be strong enough. Ariel. (talk) 19:22, 4 October 2010 (UTC)

I would take a long sheet of plastic wrap. Cover one half of it with batteries, leaving about 1/4 inch of space between each battery. Fold the other half of plastic wrap over the batteries. Fold up the sandwich and shove it in a box. --Chemicalinterest (talk) 20:08, 4 October 2010 (UTC)

DO NOT stack them in a tube or a similar configuration without insulating spacers. This was my first idea that pooped up in my head but the next second I realized that the voltage end to end would be 900V!!! --Gr8xoz (talk) 20:47, 4 October 2010 (UTC)

Yes, that would be so much voltage, although the stack will be 96 cm long. Did you know the first two numbers on a battery indicate its diameter in mm. So CR2032 are 20 mm. The 32 stands for how many 1/10mm it is thick. So it is 3.2 mm thick. --Chemicalinterest (talk) 23:05, 4 October 2010 (UTC)

Interesting. What does "CR" stand for? 92.29.115.43 (talk) 18:58, 5 October 2010 (UTC)

From CR2032 battery: C means that it is a lithium electrode and R that it is round. Beach drifter (talk) 19:25, 5 October 2010 (UTC)

Stack them in a plastic tube with the bottom end sealed. Or to be fancy, stack them in a plastic tube with the top end sealed and a little trapdoor at the bottom to use as a dispenser. Cuddlyable3 (talk) 20:00, 6 October 2010 (UTC)

Passage of Time

If the earth's velocity through space is not constant then doesn't that imply that time as we perceive it is not consistent throughout our lifetime? Or if the earth increases (via radiation from the sun and meteorites) or decreases (via sending probes and satellites into space) in mass then doesn't that also affect how we perceive time? So one minute when I was 3 could vary in length from one minute when I was 25? —Preceding unsigned comment added by 165.212.189.187 (talk) 19:55, 4 October 2010 (UTC)

How would you know? You can only measure time by comparing to something else. But yes, if mass changes, time does too. Speed does it too, but in a more complicated way. Ariel. (talk) 20:06, 4 October 2010 (UTC)

No, a minute is by definition a unit of time so, by definition, two minute long events have the same duration regardless to where in the universe you happen to be. 67.78.137.62 (talk) 20:07, 4 October 2010 (UTC)

I do not think it is that simple, there are two aspects of this:

Previously seconds and minutes was defined in terms of the rotation and orbit of earth, depending on the timescale used compensations for this is still introduced, e.g. leap seconds (61 s in some minutes).

Relativistic effects, if the earth change speed or mass the time on earth will get an other “speed” relative to the rest of the universe. The local “length” of one minute on earth is still exactly the same and all processes is affected in the same way.

--Gr8xoz (talk) 20:40, 4 October 2010 (UTC)

Time is relative. —Preceding unsigned comment added by 165.212.189.187 (talk) 20:18, 4 October 2010 (UTC)

Yes, time ir relative, but a minute is a minute is a minute. Here's an analogy: Two runers are coming down a curve on the road. The outside runner has a longer distance to go to the final line than the inside runner just because he is on the outside track. Distance is relative! And yet, a meter is still a meter. 67.78.137.62 (talk) 20:35, 4 October 2010 (UTC)

That is a bad analogy. A minute measured inside Earth's gravity well will not be the same duration as a minute measured outside of Earth's gravity. If you're standing next to the earthbound clock you will observe that the spacebound clock is running too fast. If you're standingfloating next to the spacebound clock you will observe the earthbound clock running too slowly.

I am 67.78.137.62 above. I am a physics professor and know all about relative time. The problem is not with my answer, but instead with the question asked. The length of a minute doesn't get any longer or shorter. Read my analogy again and see if you understand it this time. It is quite instructive. 174.58.107.143 (talk) 04:34, 5 October 2010 (UTC)

I agree, it's a good (and close) analogy. The elapsed time as measured by your wristwatch (which is also the rate at which you think, age, etc.) is the length of your worldline in spacetime. If you only care about clocks that are near Earth's surface then it doesn't matter how Earth is moving relative to the rest of the universe, for the same reason that if you only care about the relative distance traveled by the runners, it doesn't matter how the track is oriented relative to the north pole or the Moon. Though Earth's motion doesn't matter, its rotation (around its own axis) does, because a helical curve is longer than a straight line pointing in the same direction. Gravitational effects can be included in the analogy too. If you imagine that the race course is extremely long and both tracks run east-west, the runner farther from the equator will have less distance to travel; that's (closely) analogous to gravitational time dilation. Furthermore, if the runners ignore the tracks and run in a straight line (great circle), they will veer toward the equator. That's analogous to the gravitational force. -- BenRG (talk) 07:27, 5 October 2010 (UTC)

Similarly, if you were floating in space watching clocks on earth, you would observe that time is running slower on Earth now than it did twenty-two years ago. (That is to say that the minutes appear longer.) This is because the Earth has gotten heavier.

(For those of us stuck here on Earth for the whole time, there is no observable change, because we slow down just as much as our clocks do.

All of these effects are incredibly tiny because the Earth just isn't heavy enough to cause really dramatic time dilation.

Here is an article Gravitational_time_dilation. APL (talk) 20:44, 4 October 2010 (UTC)

Another thing to check out: Twin paradox. --- cymru lass ^{(hit me up)}⁄_{(background check)} 23:46, 4 October 2010 (UTC)

The difference in the passage of time between years is too small to be of any effect with current measuring technology. On the other hand, the change in "clock speed" over any given year is significant: basically, if you think of someone floating in space way above the Solar System and observing clocks on Earth then, to the space observer, Earth clocks run slowest in January and fastest in June. This is because the Earth is closest to the Sun, and moving fastest along its orbit, in January. Physchim62 (talk) 02:04, 5 October 2010 (UTC)

How fast would you have to be going to get to Jupiter in a year?

Let's say Jupiter is right above, like, you can fly directly at it, so it will take you one year to get there. How fast would you have to go to get there? In miles per hour, preferably. Thank you!--Editor510 ^{drop us a line, mate} 20:46, 4 October 2010 (UTC)

I assume that you're postulating that Jupiter and Earth are in alignment relative to the Sun, so that the distance between the two is the difference between the average orbital radii, and that you're looking for an average speed? If so, the orbital information may be found at Jupiter and Earth (semi-major axis is what you want), and you can do the math from there. Acroterion _(talk) 20:53, 4 October 2010 (UTC)

I got roughly 20km/sec, which is roughly equal to 45,000 mph. I could not tell you when the window for that trip would be though. Googlemeister (talk) 20:56, 4 October 2010 (UTC)

(edit conflict) It's a bit trickier than that, since Jupiter is moving, so you need to aim for where it is going to be in one year, and arrive at that time. Aiming for the average distance from the sun between Jupiter and Earth is meaningless, since, depending on the time of year for each planet, you could be off by a factor of two or more. You need to know a) what day you plan to leave Earth and b) where Jupiter will be when you get there. Simply aiming for Jupiter's orbit means that you may sit around and wait for several years before Jupiter comes by and picks you up, a very inefficient way of doing it. It would probably take a bit of calculus (simple calculus, but calculus none the less) to calculate the travel time between two co-moving bodies. --Jayron32 20:59, 4 October 2010 (UTC)

Oh no, it's for a hard science fiction story, so, I think Googlemeister's answer handles everything.

Resolved

--Editor510 ^{drop us a line, mate} 21:01, 4 October 2010 (UTC)

If it is a true hard science fiction story i think you want a more realistic mission profile, to travel in a straight line at constant speed is ridiculously inefficient since you will need to compensate for the suns gravity, and the speed of the earth and then you need to match the speed of Jupiter. A god place to get this type of info is [11], in this case the sub-pages [12] and [13] are relevant. --Gr8xoz (talk) 21:29, 4 October 2010 (UTC)

For hard hard SF, see Hohmann transfer orbit. --Stephan Schulz (talk) 21:36, 4 October 2010 (UTC)

And consider whether your space-program would prefer a Hohmann orbit, or a minimum energy transfer orbit, or some other orbit profile. The most practical orbit is an engineering tradeoff; it has to do with how long you want to provide life support; how much radiation shielding you want to provide for the astronauts; whether you can afford to put a lot of mass into low-earth-orbit; how the mass (i.e., fuel) is expended throughout the orbit profile. For example, if you want to reach Jupiter in a hurry, you arrive at the planet traveling very fast. Then you must spend a lot of fuel to slow down ("capture"). So this means you have to carry a lot of fuel with you, i.e. a larger spacecraft - which exponentially increases the mass you had to take to low-earth orbit. On the other hand, you can design a "direct descent" orbit scheduled to arrive at Jupiter with zero velocity relative to the planet; but it will take dramatically longer to arrive, and your engineering burden is much harder (because you have fewer opportunities for trajectory correction maneuvers if you aren't carrying fuel with you). Such engineering tradeoffs are easy to work out in science fiction, because you don't have to worry about a budget. Nimur (talk) 22:30, 4 October 2010 (UTC)

(5-1)AU * 93e6 miles/AU / 365.24 days/year / 24 hours/day = 42 438 miles/hour, AU is the Astronomical Unit, the distance from sun to earth, Jupiter is as closest 5 AU from the sun. This asumes that you move in a stright line and time it so you arive at the same time as jupiter. ofcurse this is not a realistic way to travle to jupiter. —Preceding unsigned comment added by Gr8xoz (talk • contribs) 21:04, 4 October 2010 (UTC)

Thank you, but, as you can see, I posted a {{resolved}} meaning I got the answer I wanted. No mission profile is needed, but I appreciate the help. :)--Editor510 ^{drop us a line, mate} 21:38, 4 October 2010 (UTC)

The OP doesn't specify whether you need to arrive at Jupiter alive or squashed. Check this information about g-force before planning your trip. Cuddlyable3 (talk) 19:49, 6 October 2010 (UTC)

Not an issue. He could accelerate to (and from) 42,438mph in just over half an hour at 1g acceleration. [14] APL (talk) 21:09, 6 October 2010 (UTC)

October 5

E=mc²

Is there a way to derive E=mc² without integral calculus? 74.15.136.172 (talk) 00:02, 5 October 2010 (UTC)

Well, the original derivation required no calculus (just some clever algebra), I'm fairly sure: [15] --Mr.98 (talk) 00:15, 5 October 2010 (UTC)

By dimensional analysis, any high school student with a basic knowledge of algebra and of physics should be able to determine that the units of measurement require the E=mc² equation, perhaps with some proportionality constant multiplied by side of the equation. What are the units of energy? Kilogram meters squared per second squared. What are the units of mass? Kilograms. What are the units of c²? Meters squared per second squared. Then see if any other power would allow the equation to balance. For instance, if I asserted that "E=mc" you could easily prove me wrong, the same as if I asserted that "E² =mc" or that "E⁷=m⁴c³. Outside the Einstein equation, you would be required to assert that "meters = meters cubed " or some such obvious nonsense. Edison (talk) 01:19, 5 October 2010 (UTC)

Dimensional analysis tells one that a mass multiplied by a velocity squared gives a result that has the same base units as an energy unit, but I would hesitate to call that any sort of 'derivation'. (Consider that atomotive fuel efficiency is often cited in liters per 100 km — volume per length, which is dimensionally equivalent to an area. Nevertheless, it wouldn't make intuitive or physical sense to describe one's mileage in units of square meters.) It's possible to determine that E=mc² contains all the terms to the correct order to give energy, but that's a very thin explanation, and it doesn't tell us why no other physical constants or measurements don't play a role. For example, E = Gm²/l, where l is the length of the object, m is its mass, and G is the gravitational constant also gives the correct units, but is a totally meaningless formula. TenOfAllTrades(talk) 02:51, 5 October 2010 (UTC)

While the rest of your comment is spot on, it is both intuitive and physically meaningful to speak of fuel consumption in terms of area (or fuel efficiency in terms of inverse area). The area is the cross section of fuel needed to travel a given distance, if that volume of fuel is stretched out over that distance. So if my tractor consumes 1 l / km = 1 mm^2, then it could travel indefinitely were it fed by a prepositioned fuel supply of 1 mm^2 cross sectional area along the route traveled. -- ToE^T 10:32, 5 October 2010 (UTC)

In the article the guy above linked to, how did the equation l' = l(1 - (v/c)cosθ)/sqrt(1 - (v/c)²) come about? 74.15.136.172 (talk) 02:57, 5 October 2010 (UTC)

That first equation is just the Lorentz transformation of the photon energy, where the Lorentz boost is at an angle $\phi$ to the photon momentum. You can see a Lorentz boost in a general direction at the bottom of this section. 129.234.53.175 (talk) 14:57, 5 October 2010 (UTC)

I didn't understand half of the above; but I did enjoy Brian Cox's Why Does E=mc²?[16] Bazza (talk) 14:49, 5 October 2010 (UTC)

There is no real rigorous derivation of E = m c^2. You have to ask yourself from what theory you want to derive this from? Obviously, any rigorous derivation has to start from the postulates of special relativity, but then the derivation is trivial. Rather what passes for a derivaton of E = m c^2, is a heuristic arguments for thehttp://en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&action=edit&section=26 correct equation. Einstein's argument makes electromagnetism compatible with mechanics, but then electromagnetism is obviously already a relativistic phenomena. A rigorous agument obviously would not be allowed to invoke the properties of electromagnetic radiation!

Einstein later gave a similar argument (I think in 1936), which is far simpler. Suppose you have two objects of mass M floating in space, a distance L apart at rest w.r.t. each other. No external forces act on the masss. Then one object emits a photon of energy E, which is absorbed by the other mass. The photon as a momentum of E/c, so when one object emits it, it gets a velocity of v = E/(M c). The photon reaches the other object in a time of t = L/c. By that time the object that emitted the photon has moved by a dstance

d = v t = E/(M c) L/c = E L/(M c^2).

So, this suggests that in the original center of mass frame, the center of mass of the two object system will move by a distance d/2. But ths can't be true, because there are no external forces acting on the two objects. The exchange of the photon happened within the two object system, so momentum must be conserved. In the original center of mass frame, the momentum must remain zero and the center of mass cannot have moved at all. But the end result is undeniably that just after the photon has been absorbed, one object has moved by a distance d. So, if the center of mass does not move, then the masses must have changed.

If an amount of mass delta m has been exchanged in this process, then that would contribute to a shift in the center of mass of (delta m L)/(2 M) in the opposite direction. This has to compensate for the shift of d/2, so we find that:

delta m = M d/L = E /c^2

Count Iblis (talk) 15:13, 5 October 2010 (UTC)

I don't know whether this counts for your purposes as a derivation, and it's probably what Count Iblis would consider trivial, but from the definition of the four-momentum $(E/c)^{2}-|{\vec {p}}|^{2}$ (where ${\vec {p}}$ is the three-momentum) is an invariant quantity, which turns out to be equal to the square of the rest mass times the speed of light, all squared: $m_{0}^{2}c^{2}$. It's only a few bits of algebra from there to $E^{2}=m_{0}^{2}c^{4}+|{\vec {p}}|^{2}c^{2}$ and $E=mc^{2}$ drops out when ${\vec {p}}$ is small, or 0 as must be in the particle's rest frame, by definition. Couple of fun things that follow from this are a definition of momentum for a massless particle like a photon as $E/c$, and the fact that taking the negative square root possibility (i.e. $E=-mc^{2}$) seriously is what first led Dirac to think about antimatter, though we now tend to think about it rather differently. --81.153.109.200 (talk) 16:08, 5 October 2010 (UTC)

On another tangent...

This question or ones like it come up from time to time, and eventually something in the back of this very old mind fired. I took QM in 1971 -- it's possible that some of the concepts have changed a bit since then :-) .

If I Recall Correctly (not guaranteed!), the most significant part of Einstein's famous equation is not what you see, it's what you don't see. Starting in high school Physics, everybody learns that potential energy of a moving particle is ½Mv². No problem.

As v approaches c, what happens to the ½? That's the insight that Al brought to the table. Isn't it?

DaHorsesMouth (talk) 01:37, 6 October 2010 (UTC)

I do not think that is correct. E=Mc² is not the kinetic (i think you meant kinetic not potential energy) of a mass at the speed of light but the total energy of the mass regardless of speed. The kinetic energy goes towards infinity as the speed goes towards the speed of light in vacuum. --Gr8xoz (talk) 04:00, 6 October 2010 (UTC)

I concur. I always thought it was neat (and maybe instructive) that you can see the two contributions to the energy appear distinctly in the low-speed limit of the relativistic energy expression:

$E=\gamma (v)m_{0}c^{2}={\frac {m_{0}c^{2}}{\sqrt {1-v^{2}/c^{2}}}}\approx m_{0}c^{2}\left(1+{\frac {v^{2}}{2c^{2}}}+...\right)=m_{0}c^{2}+{\frac {1}{2}}m_{0}v^{2}+...$

It's always reassuring to see familiar limits. 129.234.53.175 (talk) 13:24, 6 October 2010 (UTC)

DNA

Is it possible to obtain a DNA sample from a living person, and another sample later on, of a deceased person, and confirm that the sample is from the same person? Also are you able to tell approximately the time/date of death from a DNA sample? Can DNA show medical conditions such as diabeties or cancer? —Preceding unsigned comment added by Aneelr (talk • contribs) 01:11, 5 October 2010 (UTC)

Yes, no, no (but DNA could show a tendency toward diabetes or cancer). (I pronounce myself subject to correction on the third answer). Edison (talk) 01:22, 5 October 2010 (UTC)

DNA can show if you have a Genetic predisposition toward a disease.Smallman12q (talk) 02:01, 5 October 2010 (UTC)

Certain diseases, like Cystic Fibrosis, are completely determined by DNA. It is pretty trivial to tell whether a person has cystic fibrosis (or more importantly, whether they are capable of passing it on to their offspring) by looking at only a small section of their DNA. Such testing is a common way to determine if a baby has Cystic Fibrosis. Tay-Sachs disease is another such disease. With both of these examples if a person has two recessive copies of a particular gene, they have the disease. If they don't, they don't. There are different tests for each disease, including a genetic test for each. While it is typical to only perform such tests on a living person, I see no reason why it could not be performed on the DNA of a deceased person, provided the DNA had not degraded too much. Buddy431 (talk) 02:13, 5 October 2010 (UTC)

You might be able to tell if a person has a viral infection, or even certain types of cancer, through a DNA test, but (as I understand it) there's a risk of false negatives – i.e., that the person has the condition but you don't see it – when you are just running a standard DNA test from a single biological sample. So, if you had a sample of breast tissue, you might be able to tell if the woman concerned had breast cancer from a DNA test, although there would be simpler ways of doing it, the DNA test usually comes after you've confirmed cancer by more traditional means. If you could reliably tell that a woman had breast cancer through a DNA test on a blood sample, you would become very rich indeed. Each cancer is distinct in this respect: leukemias, for example, should be much easier to detect by DNA testing on blood than cerebral cancers. Physchim62 (talk) 02:54, 5 October 2010 (UTC)

In general, we expect a person's DNA to remain exactly the same throughout their life. DNA mutations happen a cell-at-a-time, so if a mutation does occur, there's no reason to believe that any other cell in the body has that same mutation (unless the mutation causes the cell to reproduce out-of-control). DNA is great for identification because of its constancy. Paul (Stansifer) 19:43, 5 October 2010 (UTC)

Robert G. Edwards

After how many year since he first developed the in vitro fertilisation until he got the Nobel prize?174.20.65.111 (talk) 02:21, 5 October 2010 (UTC)

From our article on Robert G. Edwards, the first in vitro fertilization of a human egg was in 1968 (42 years ago), and the first baby born using the technique was in 1978 (32 years ago). Physchim62 (talk) 02:25, 5 October 2010 (UTC)

WOW he finally got the Nobel prize after like 40 years. The Nobel prizes reward are too late! Some people may not live that long to receive what they deserve.174.20.65.111 (talk) 03:16, 5 October 2010 (UTC)

It's particularly impressive in view of the fact that Nobel's will, which set up the prizes, specified that they should be for work done in the past year. But there are good reasons why it was felt that following this rule was inappropriate. See Nobel Prize#Recognition time lag. --Anonymous, 03:25 UTC, October 5, 2010.

Indeed. In this case, Edwards had a coworker called Patrick Steptoe, who was a gynecologist and developed laproscopy to collect the eggs needed for IVF: Steptoe died in 1988, so never received the Nobel Prize that many believe he deserved. Physchim62 (talk) 03:32, 5 October 2010 (UTC)

Note that the Fields Medal, sometimes referred to as the "Nobel Prize of Mathematics", is only awarded to mathematicians under the age of 40, because "... while it was in recognition of work already done, it was at the same time intended to be an encouragement for further achievement on the part of the recipients ...". As a result, Andrew Wiles did not receive one for his proof of Fermat's Last Theorem, however the IMU did presented him with a plaque which has been referred to as a "quantized Fields Medal". -- 124.157.234.91 (talk) 09:00, 5 October 2010 (UTC)

Good-smelling bad smells

Under our kitchen sink we keep a coffee container of old coffee grounds and the juiced parts of fruits and veggies. When I open it u to add to it, I try to breath out of my nose for fear of getting a whiff of foul smelling compost. To my surprise this evening I opened it and got a not so offensive smell up my nose, and, in fact, it smelt good, like a bad-selling flavor of ice cream. What causes this? Thanks Wikipedians! schyler (talk) 02:45, 5 October 2010 (UTC)

Coffee grounds are a cheap deodorizer. They are known to be used, for example, at perfume counters in stores to "clear the palate", so you can properly smell each perfume and not keep smelling the previous perfumes. It is likely that the coffee smell overwhelms your sense of smell in general, which "clears out" the other smells. this Google search turns up lots of stuff on using coffee in this way. --Jayron32 03:12, 5 October 2010 (UTC)

If your house is warm enough, the fruits and veggies may have begun fermenting. While I wouldn't call that smell especially pleasant, there is a sickly sweetness to it that might be reacting well to the coffee. Hobo Irish-Cream ice cream, perhaps? Matt Deres (talk) 04:30, 5 October 2010 (UTC)

Pruno perhaps? --Jayron32 04:33, 5 October 2010 (UTC)

Gravitational constant

why does the gravitational constant decrease when we go towards the centre of the earth? —Preceding unsigned comment added by 120.56.189.145 (talk) 07:35, 5 October 2010 (UTC)

It doesn't. The Gravitational constant is, as its name suggests, a constant (unchanging) value. The actual gravity experienced may however vary, so perhaps you are thinking of that; see Earth's_gravity#Variation_in_gravity_and_apparent_gravity. --jjron (talk) 07:57, 5 October 2010 (UTC)

Yes. Basically the reason is simply that when you are below ground, some of the Earth is above you, so it is pulling you upwards instead of downwards. --Anonymous, 08:00 UTC, October 5, 2010.

See shell theorem. The outer shell of the earth, above you, does not attract you at all. 157.193.175.207 (talk) 08:00, 5 October 2010 (UTC)

Re 157.193.175.207 - that would seem to be assuming a hollow sphere (point 2) so not apply; the Earth is obviously not hollow, so would more closely approximate point 3, i.e., "...the gravitational force varies linearly with distance from the centre, becoming zero at the centre of mass." --jjron (talk) 08:27, 5 October 2010 (UTC)

No, it doesn't assume a hollow sphere. You can write the total force caused by the (full) earth as the force caused by the (full) sphere beneath you (whose mass varies as r^3 and r^3/r^2=r thus linear) + the force caused by the (hollow) shell above you (which is 0). The variation isn't caused by the upper layers attracting you in the opposite direction, it's because the upper layers don't attract you at all, thus only the mass beneath you influences g. 157.193.175.207 (talk) 09:19, 5 October 2010 (UTC)

Obviously each individual part of the shell does exert a gravitational attraction - gravity isn't switched off. But inside the shell, the attraction due to a specific part of the shell is balanced by an equal and opposite gravitational attraction from another part of the shell. So the net gravitational attraction due to a hollow spherically symmetric shell is zero at any point inside the shell. The rest of the analysis above is fine. Gandalf61 (talk) 11:10, 5 October 2010 (UTC)

The shell theorem assumes a uniform shell, which is not the case for a real Earth with a non-homogeneous, constantly-convecting interior. The correct solution is to actually integrate the density for each unit-volume. The shell theorem will still approximately hold, because azimuthal density variations in the density of earth's interior are small relative to the scales involved. Nimur (talk) 17:59, 5 October 2010 (UTC)

At that level of detail, you'll probably want to include the effects of the Sun and the Moon (etc., etc.) as well. -- 140.142.20.229 (talk) 21:55, 5 October 2010 (UTC)

But then we get into discussions of Mach's principle, which if you take it seriously enough means that we have proof that the cosmological assumption of a homogenous and isotropic universe on large scales holds, and we don't have something like a fractal cosmology. --81.153.109.200 (talk) 05:35, 6 October 2010 (UTC)

Dealing with excessive moisture inside an apartment...

As autumn progresses into winter, we are getting more and more condensation on the interior surfaces of our windows. This led to a serious mold problem in one particular corner last year. I'm a bit at a loss as to how to lower the humidity of our apartment's air without resorting to opening the windows and freezing ourselves. Currently, I'm simply wiping down the windows. That prevents pooling along the sills, but only transfers the moisture to the towels -- it's still in the apartment and when the towel dries the moisture has simply returned to the air. Thus the cycle continues. We don't have an electric clothes dryer, and we have under-floor heating. I suppose I could leave the oven door open... Suggestions? The Masked Booby (talk) 09:24, 5 October 2010 (UTC)

Dehumidifier? You could pour the water down the sink. Dismas|^(talk) 09:44, 5 October 2010 (UTC)

Our article on dehumidifiers does not mention the small, cheap, chemical dehumidifiers you can get. These use a sachet of crystals which absorb water from the air. DuncanHill (talk) 09:46, 5 October 2010 (UTC)

Some form of dehumidifier is definitely the only good option here - in some way, you need to reduce the amount of water vapour in the air. By the sound of the original question, the scale of the problem here may be beyond efficient usage of chemical dehumidifiers, and one of the electrically-powered ones would strike me as a good investment. It may be worth leasing one for a week or two from an equipment hire company, just to see to whether it effectively solves the problem or not - you can then consider buying one. ~ mazca ^talk 10:08, 5 October 2010 (UTC)

Why would leaving the oven door open help? Your problem is that warm, wet air is hitting the window, which is cold from the cold outside, and water is condensing out. Solutions are: warm the inside of the window (double glazing helps, if you can get it, or directing warm drier air to blow over the window as in a car) and reduce the moisture in the air (you can achieve some of that by turning the heating down, but I'm guessing that would get unpleasant). A cheap, passive dehumidifier using cheap, replacable crystals that dissolve as they absorb the water, may be your best bet, although you may need several large ones scattered in the worst spots. I've also had luck using anti-mould spray (in a well-ventilated room), which then reduced later mould growth. 109.155.37.180 (talk) 09:58, 5 October 2010 (UTC)

In winter humidity is already pretty low, if you dehumidify on top of that you will have a very unpleasant living experience. Can you read the Dew point article, and estimate what temperature your window is? Look specifically at the section "Calculating the dew point". I think you will find it's impossible to dehumidify your apartment enough. You can lower the temperature of the apartment, or insulate the windows.

My suggestion: Get those plastic window films that cover the entire window (something like this, or just google for "Plastic Window Insulation"). Use that to insulate the window to some degree. Your second option is to give the moisture a place to drain - drill holes in the sill probably. Ariel. (talk) 10:59, 5 October 2010 (UTC)

Approach it systematically. Identify all the things that put moisture into the air. Breathing, house plants, cooking, gas cookers (two molecules of water form every one of methane burnt), portable gas fires, perfume candles, hot showers/baths, boiling kettles etc. Then look at all the reasons the moisture content remains high (water has a very high vapour pressure and it wants to get out into the blue yonder). People with under-floor heating often find it expensive in properties where the floor is not insulated properly to stop the heat being conducted downwards. So they draft-proof the house till is near air tight and unhealthy. Can't remember the numbers of cu ft per hour it thought human needs but you need, but the air itself needs to have been completely changed over the course of two hours in a normal house. Get a good electric hygrometer. Cheap hair tension hygrometers are nigh on impossible to calibrated properly. Check the Relative Humidity reading for each room. If anywhere is equal to, or more than 45% Relative Humidity and if the RH higher than that outside then you definitely do not have enough ventilation. Moist air rises so you only need a high window to be part open in that room. That should not overly cool the room. Try turning the floor heating down and use a fan heater as a supplement, if the floor heating is inefficient and wasteful. Some windows and wall have small ventilation ports which have been blocked up- reopen them as that's what they are their for. If you in an oldish apartment with people living below, the service pipe runs may be a conduit for all their moisture laden air to enter your apartment, so check that. This may be all that needs to be done to mitigate the problem. Dehumidifiers make a noise when running, and although cheap to run in the US they are much more expensive in Europe and else where . So it is worth doing these checks first.--Aspro (talk) 16:21, 5 October 2010 (UTC)

The question is very puzzling.I consulted with the guy from the hardware store. Where is the moisture coming from? In the baseline case, if the inside temperature is higher than the outside temperature due to a furnace, the relative humidity inside will be lower than the outside r.h., with similar dew points, and there should be "dry air" inside leading to static shock from shuffling on the carpet, and nosebleeds due to dry air. That is the case in my home at present, with no humidifier operating and the furnace operating. If there is a humidifier, or if you have water boiling on the stove all the time, or if you run the shower a lot, or if you operate a clothes dryer without venting it outside, then the relative humidity inside might be so high that water condenses on the windows. Dehumidifiers are rarely needed in the winter. The basic process of space heating lowers the humidity so much that static electricity and dry nose rule, and furniture dries out so the wood cracks and the joints come apart. Is there a humidifier on the furnace and is it set too high relative to the outside temperature? Edison (talk) 04:18, 6 October 2010 (UTC)

OP here. I really appreciate you guys trying to help. It seems some regional differences are at the cause of my unusual problem... I live in NE China. We have under-floor heating supplied at will by the local government. We cannot control the temperature, nor can we control when it's on or off. We just get it. Also, we don't have a clothes dryer and hang-dry all the laundry indoors during the winter. (the coal soot and dust air pollution here will ruin anything hung outside) Combined with 2 people showing each morning, our 115 square meter apartment gets pretty humid. Thank you to everyone who has made suggestions so far. I'm going to keep monitoring this question for any new feedback. The Masked Booby (talk) 07:40, 6 October 2010 (UTC)

That clothes drying and showers could certainly supply enough moisture. If you could exhaust the air from the shower while using it, that would be some progress. Otherwise you may need a heat exchanger to draw in outside air and heat it with air leaving, but it sounds as if you need to filter this air too. This is hard to fit in an apartment. Electric dehumidifiers can work, but make sure they drip their water down a drain. Graeme Bartlett (talk) 09:54, 6 October 2010 (UTC)

Getting some sort of small clothes dryer and venting it outside, as well as venting moist air from the shower outside via a small exhaust fan in the bathroom window, would greatly lower the relative humidity. A mechanical wringer ($100 to $150 US) would be a green way of reducing the moisture evaporated into the air by sending more of the clothes dampness down the drain immediately after washing. There are also little clothes dryers for under $100 (US) which dry small loads on the countertop mechanically by spinning, like a centrifugal extractor. Edison (talk) 19:44, 6 October 2010 (UTC)

The problem with many of the suggestions is that they require a)access to enough money b)access to enough supplies c)access to lots of cheap electricity d)lots of room e)ownership of the apartment, allowing changes to be made f)supervision of constantly-running electrical equipment. I'm guessing you do not have these. Opening as high a window as possible when showering and leaving it open for 10 minutes might help. Improving the windows or adding something to drain or absorb water as it drips down might help, as long as you drain that water out of the apartment fairly regularly. Treating the surface with bleach after you scrub the mould off might help. Passive chemical dehumidifiers, if you can get them, can be left to work when you are at work or asleep, although they probably won't be enough by themselves. Reducing the water in your clothes, either with a mangle or by giving them an extra spin in the washing machine (if you have one) will help. 109.155.37.180 (talk) 00:05, 7 October 2010 (UTC)

There are no problems with running most electric dehummifiers running unsupervised. --Gr8xoz (talk) 08:25, 7 October 2010 (UTC)

Install double- or even triple-glazing to the windows. This means that the inside surface of the windows will be less cold, so there will be less condesation. The glazing does not have to be glass, it could be a thin sheet of plastic such as cling-film. And you could use a squeegee or sponge to collect the condesation instead of towels, so that you get liquid water that you can pour down a drain. 92.15.10.67 (talk) 22:29, 7 October 2010 (UTC)

HIV infection through childbirth?

I've heard that most infants whose mothers are HIV-positive contract HIV through childbirth, which confuses me. Wouldn't they contract it in utero? During gestation, the mother shares nutrients, etc. with the fetus through the umbilical chord. Isn't it likely that during those 9 months, the child would contract HIV, instead of at childbirth? --- cymru lass ^{(hit me up)}⁄_{(background check)} 14:01, 5 October 2010 (UTC)

The placenta blocks transmission in utero in most cases, but during passage through the birth canal there is a risk of transmission. --14:10, 5 October 2010 (UTC) —Preceding unsigned comment added by 81.153.109.200 (talk)

This was discussed just above. The placenta blocks the HIV virus from passing in most cases. Regards, --—Cyclonenim | Chat  14:18, 5 October 2010 (UTC)

Paleontology

Mostly to get new knowledge (I am a retired teacher of math- phys,M.Sc) I am at present reading T. S. Kemp: The Origin and Evolution of Mammals. After that I would like to learn about anapsid and diapsid animals in the Permian —Preceding unsigned comment added by 87.54.145.241 (talk) 14:13, 5 October 2010 (UTC)

Okay, so what would you like us to do? Find books on anapsid and diapsid animals in the Permian for you? Regards, --—Cyclonenim | Chat  14:19, 5 October 2010 (UTC)

Wow! You're in a bad mood today! You might prefer to stay off the reference desk for a while if you're just going to bite at people. Physchim62 (talk) 15:40, 5 October 2010 (UTC)

Sorry, that wasn't meant to come across as 'biting'. It was a mere request for clarification. I didn't think it was worded particularly badly but if it offended the OP then I apologise. Regards, --—Cyclonenim | Chat  15:45, 5 October 2010 (UTC)

It can be read in two ways, I think. I initially read it as confrontational but then realised it was just asking what the OP was after, so it all works out ok. Don't panic. Brammers (talk/c) 17:17, 5 October 2010 (UTC)

We have articles on both anapsids and diapsids that should give you a starting point. Mikenorton (talk) 14:26, 5 October 2010 (UTC)

I think there is a good chance the OP meant to ask about synapsids (the group that includes mammals) rather than anapsids (a group that mainly includes turtles). Looie496 (talk) 14:52, 5 October 2010 (UTC)

In-line duct heater

Why is something like this [17] so expensive? I don't think it is anything except a section of tubing, an element, a thermostat and a cut-out, i.e. the same set of components as an electric kettle but more crudely made? I have an existing heater like this but it isn't working. It was always a bit prone to cut out and then difficult to reset, and now it doesn't want to reset at all. Would a competent electrician be able to repair it? Could a DIY enthusiast realistically make one? I don't want simply to order this at the price, but the winter is coming... (We don't seem to have an article on duct heater). Itsmejudith (talk) 15:28, 5 October 2010 (UTC)

In theory, you could stick an electric kettle in your vents, crank it up to max heat, and use it to heat your place. In practice, you will most likely burn your home down. The big difference is safety - which is important when placing a very hot heating element in a confined space. As for what is wrong with your heater, we don't know. Perhaps the heating element is burned out. Without knowing what is wrong with it, it is impossible to determine if it can be repaired at a cheaper price than purchasing a new one. As for repairing it yourself, I wouldn't suggest that a person should mess with something that has the potential of electrocuting them and/or burning down their house. But, that is just my opinion. -- kainaw™ 16:28, 5 October 2010 (UTC)

Why is it so expensive:

1) It comes with on site warranty.

2) The retailer is selling slow moving inventory from stock and promising fast delivery, good service and with technical backup by phone. All that is included in the price

3) It is made by a firm known for its quality.

4) As above, and if you should buy this brand more cheaply from a suppler without the on-site warranty (and service etc.) and a bit eventually needs replacing, you will be able to just buy a spare without having to but a whole new unit like with some cheaper other manufactures of the same type of heater.

5) The heating elements are much larger than in a kettle and it needs to be built to a higher standard for commercial installations. There is a lot more material also. So its not a fair comparison.

6) In a commercial environment is cheaper than buying a cheaper one which will need replacing every few years.

If you still think its expensive, just imagine how much it would cost if your dentist was selling them! Have had experience of buying and using products from both companies--Aspro (talk) 17:11, 5 October 2010 (UTC)

Perhaps 4) above applies though. Perhaps just one component of the existing one needs replacing (it is the same make as this). Is it worth asking a qualified electrician to have a look at it? Itsmejudith (talk) 17:35, 5 October 2010 (UTC)

This is how I would go about it. Redring is now part of the Applied Energy group. It looks like the duct heater is a re-branded Xpelair design Inline Duct Heater. There is no need for Redring to redesign from scratch if there exists a good design already, so the part numbers and everything should be the same I expect. I would find that out for sure by first making it safe electrically. It will likely have its own fuse on the switch board. Take precautions to prevent anybody re-establishing the current whilst I'm working on it. The take the whole unit out and have a look. It might just need a ruddy good clean. With some cut-outs, dust gets behind the switch and stops it re-setting. Blow it out and its OK again. A high street stockist (Applied Energy website will tell me my closest one) will probably want to sell me a whole new unit if I just take it into them. So I would have a look at the thermal cut out and meter the heating element as well to see if that's OK. Bung the sensor into hot water to see if that works too. Then phone up and see if they stock the individual spares. If they do and I don't feel competent to put it all back together again. That is when I would say to a qualified electrician: I've got all the bits can you reinstall it? A lot depends on how good the electrician is. It is more messing about for him to buy the parts himself and he might end up charging you more that it would cost to buy a new unit because of the hourly labour charge. So you will have to play that by ear. Alternatively, you could start of by saying you have a 'Redring' in-line heating duct so he knows it not a cheap and crappy one. Then say you might get it repaired if it ain't too much. Then ask if his quote will be any less if you got the parts yourself. If you can find electrician that works on ducting all of the time he may already have a small stock of spares. A heating and ventilation installation company, may employ an electrician who is keen to take on a bit of private work. Then there is the cost of your own time to consider verses his etc. Hope this give you some ideas. --Aspro (talk) 19:32, 5 October 2010 (UTC)

BTW, to answer your question (rather than give you good advice like the other posters) the reason this (and other items, like cabinets, countertops, furniture) are so expensive is that they are hand made domestically (for whatever definition of domestic applies to you). The high prices usually continue until someone in China decides it's worth copying the item and flooding the market with cheap, but serviceable versions. This usually works better in trades where it's not a tradesman who installs the item, since they resist lower prices until they have no choice. Ariel. (talk) 19:47, 5 October 2010 (UTC)

Aspro, thanks very much, incredibly helpful. I will take the unit out, dust it down and see if that does the trick. Because the problem has always seemed to be with the cut-out. Dust inside is a likely hypothesis. At least now I know it's worth taking it out and having a look at it before splashing out on a new one. Itsmejudith (talk) 21:37, 5 October 2010 (UTC)

Percentage of common genes

What does that mean? "Fraternal (dizygotic) twins," (...) "roughly 50% of their genes are the same". If a human and an ape share 98% of their genes, how does it come that fraternal twins share only roughly 50%?--Quest09 (talk) 16:17, 5 October 2010 (UTC)

In the twins context, it's talking about them being the same allele. --81.153.109.200 (talk) 16:32, 5 October 2010 (UTC)

(after EC) These are two different ways of describing genes and genetic similarity. Dizygotic twins are no different than any other pair of full siblings -- they each inherit one copy of every autosomal gene from each parent. By chance, they will inherit the same versions (alleles) of roughly 50% of their genes. When making comparisons to other species, we are really talking about genetic homology. The genes "shared" by different species are "orthologs" -- highly similar genes that encode nearly identical proteins. In this "phylogenetic" use of the term, humans and other primates have nearly the same complement of genes, with a few hundred genes that are only found in humans and a few hundred genes that are only found in other primates. Many of the genes that are not "shared" are probably "paralogs", or gene copies that only arose during the evolution of one or the other species. --- Medical geneticist (talk) 16:45, 5 October 2010 (UTC)

Physical meaning of 1 Farad = 1 Second/Ohm

What is the physical meaning of the unit of capacitance, the Farad, being equivalent to 1 second / ohm, in a short sentence? What does a one-farad capacitor do with one ohm in one second (one second of what even?)? 20.137.18.50 (talk) 16:33, 5 October 2010 (UTC)

I am unable to confirm your assertion that 1 F = 1 s/Ω. Can you explain why you think this is so? Jc3s5h (talk) 16:42, 5 October 2010 (UTC)

http://en.wikipedia.org/wiki/Farad#Definition —Preceding unsigned comment added by 20.137.18.50 (talk) 16:45, 5 October 2010 (UTC)

It takes one second after voltage is applied to a circuit consisting of a one farad capacitor in series with a one ohm resistor for the capacitor to charge up to 1-e^-1 ≈ 63% of its final charge. See RC time constant. -- 111.84.119.217 (talk) 16:47, 5 October 2010 (UTC)

(EC) To answer the last question first, one second of time. As 111.84.119.217 says, one way to think about your question is to consider the time constant of an RC circuit, which is given by $RC$. To go into a little more detail, this is the timescale on which the charge stored drops to $1/e$ when discharging, or the charge being built up rises to $1-1/e$ when charging. So 1 F = 1 s/Ω in the sense that a 1F capacitor in an RC circuit would give you a time constant equal in seconds to the resistance of the resistor in Ohms. (Or, thinking about it the other way round, for a fixed resistance in the circuit, you would have to increase the capacitance you put in to get a longer time constant.)

To prove that $RC$ does give something in units of time, consider the basic definitions of the quantities, and what their units are expressed in slightly different terms than we usually consider them:

Charge Q is measured in in Coulombs (C).

Voltage V is measured in Volts (V), but they're really Joules/Coulomb (J/C).

Current I is measured in Amps (A) but they can also be considered Coulombs/second (C/s). [Strictly speaking, the Amp is the base unit and the Coulomb is an Amp-second, but that doesn't get to the key concepts of what's going on in a circuit quite so readily, to my way of thinking.] We'll need both of these for the two definitions we need to get to the question:

Capacitance C is Q/V so it's measured in C/V or, C²/J when you replace Volts with Joules per Coulomb. That is, 1 F = 1 C²/J.

Meanwhile, Resistance R is V/I so it's measured in Js/C² -- that is, 1 Ω = 1 Js/C².

Comparing the last two, it's fairly clear that the units of RC are seconds, and thus that 1 F = 1 s/Ω. (Incidentally, I'm convinced there's some way to consider resistance in terms of action-per-charge-squared, but I've never quite managed to grasp it intuitively. Am I just barking up the wrong tree there, ref-deskers?) --81.153.109.200 (talk) 16:59, 5 October 2010 (UTC)

OK, I agree with parts of that. In particular, I agree that the RC time constant is measured in seconds. Here is how I would reason from that:

resistance ⋅ charge = time (quantities)

ΩF = s (units)

F = s/Ω

F = s[(sC²) / (m²kg)]

F = (s²C²) / (m²kg)

Jc3s5h (talk) 17:22, 5 October 2010 (UTC)

It may also help to consider electrical impedance, which is the conceptual extension of electrical resistance to the time-varying (equivalently, frequency-varying) domain. The capacitor provides a relationship between voltage and current, similar to a resistor; but this "extension" to Ohm's Law requires a unit of frequency. It so happens that the defining equation for the capacitor's impedance could be re-arranged in an "ohm's law-like" form, where (R = V/I), so by extension, Z_cap = V/I = 1/(jωC); so a capacitance should be measured in units of time over resistance. Nimur (talk) 17:56, 5 October 2010 (UTC)

I think we can tackle this without introducing additional concepts. Let's start from the identity C=Q/V:

• C = Q/V = It/V (capacitance is the number of ampere-seconds you have to pass through a capacitor to charge it up to one volt)

Dividing numerator and denominator by amperes, you get:

• C = t / (V/I), i.e. capacitance is the number of seconds it takes to charge a capacitor up to one volt with a constant current of one ampere flowing through it.

In other words (I claim; but this is OR), 1 farad is the capacitance that would charge to 1 volt per ampere (i.e. 1 ohm) in 1 second. --Heron (talk) 18:24, 5 October 2010 (UTC)

Neither V nor I are constant as you're charging/discharging. That's where all the exponential/time constant stuff comes in. --81.153.109.200 (talk) 18:39, 5 October 2010 (UTC)

I is constant because I defined it so. V of course isn't, but my reasoning doesn't require that. --Heron (talk) 18:51, 5 October 2010 (UTC)

Your defining it to be constant does not somehow magically change the results of an experiment to measure it over time as a capacitor is charged. The only way to achieve constant I would be to constantly fine-tune the emf in the circuit as time went on. Either way, the maths gets hairier than your presentation. --81.153.109.200 (talk) 05:22, 6 October 2010 (UTC)

You just use a constant current source. Of course you can't run this for millions of seconds to get millions of volts. The opposite proposed that a constant EMF is applied to the capacitor is just as impossible, as the current influx would have to be infinite to match the charge Q=CV to the voltage. Graeme Bartlett (talk) 09:23, 6 October 2010 (UTC)

Heron and Graeme are right. The exponential time constant does not come into the definition of capacitance, it only arises when a capacitor is connected to a resistor. There are practical ways to construct a source of constant I. One way is to make a feedback circuit that keeps the input side of a 1 ohm resistor always 1 volt higher than the output side of the resistor. No hairy math is needed to do that and the voltage on the capacitor will rise linearly not exponentially. Some people enjoy the Hydraulic analogy concept of capacitance as a pipe blocked by a rubber sheet. If water (current) flows at a constant rate in the pipe (wire), the pressure difference (voltage) across the rubber sheet increases linearly. Admittedly we can't keep that going forever but 1 second is not asking much. Cuddlyable3 (talk) 12:55, 6 October 2010 (UTC)

Permanganate reaction with heat

Does any chemical reaction occur when potassium permanganate is boiled? --Chemicalinterest (talk) 17:07, 5 October 2010 (UTC)

Assuming you mean heated, not boiled (it'd have to be liquid first and I suspect this reaction happens while still in the sold phase), I suspect it decomposes via 2KMnO₄(s) → K₂MnO₄(s) + MnO₂(s)+O₂(g), just as it does on exposure to light. At which point it's no longer permanganate (there's only half a manganate ion to each potassium ion), so ... --81.153.109.200 (talk) 17:12, 5 October 2010 (UTC)

I mean boiled in a solution, sorry for the ambiguation. This is the scenario. There is a solution of sodium permanganate and sodium chloride in water. I want to remove the sodium chloride. I know sodium chloride is much less soluble in water than sodium permanganate. I want to boil the solution to concentrate the sodium permanganate and filter the sodium chloride. I wanted to know whether the permanganate decomposes when boiled for a while. --Chemicalinterest (talk) 17:19, 5 October 2010 (UTC)

irish tornadoes

Resolved

How frequent do tornadoes occur in ireland and what is our peak season is it the same as britain or somewhere else. --213.94.235.26 (talk) 19:03, 5 October 2010 (UTC)

I do not have a specific answer for you yet, but your question reminds me of a related one about tornadoes in Ireland that was asked here recently. And if I may, I thought it might address some of your interest here for me to quote from Lomn's excellent response to that question: "...however, our list of European tornadoes and tornado outbreaks notes that Ireland was home to the first recorded European tornado." WikiDao ☯ (talk) 19:45, 5 October 2010 (UTC)

Its okay I just found an article from torro after i googled it said tha 9 approsminately tornadoes touch down higher numbers are recorded in summer months but for some reason the most severe ones happen in winter and summer. --213.94.235.26 (talk) 20:57, 5 October 2010 (UTC)

Interesting. Well thanks for the question and answer both, then! Cheers, WikiDao ☯ (talk) 21:31, 5 October 2010 (UTC)

Video clips stuff for science articles

This may belong to the help desk, but I thought the science ref desk is more constructive and responsive.
I am considering producing a number of video clips (after adequate research, as I am a bear of little brain) which can be added to relevant scientific articles. Attached are some examples I have been working on. As per the guidelines, the format is .ogv in all clips. Sorry about the voice over. I did not realise that I sound like a dim-witted upper class twit straight out of Monty Python.
Please provide feed back as to the (un)suitability of the clips. I am aware that details will have to be corrected and optimized. Thank you for any help.
--Cookatoo.ergo.ZooM (talk) 19:06, 5 October 2010 (UTC) Warning: Not to be used via dialup connections. --Cookatoo.ergo.ZooM (talk) 22:17, 5 October 2010 (UTC)

Sample video clips for evaluation

Amino acids, 32 MB

DNA packing, 13 MB

Nuclear decay and nuclear fission, 13 MB

Mitosis, 12 MB

The solar system, 5 MB

Neat videos, CeZoom. :) I'm sure there are all sorts of wikilaws about this sort of thing, and someone more knowledgeable of those intricacies may come along and go into them in detail here soon. But I thought I'd mention that it might be a good idea to try to do this in a way somewhat more along the lines of the Spoken Wikipedia Project. That is, keep the visuals to strictly pertaining to the text of the article (just the same way one does with static images), and then restrict the voice-over to some version of the content of the article. Regards, WikiDao ☯ (talk) 19:59, 5 October 2010 (UTC)

Did you make these animations? They are very cool! I'm not so certain about the content though, to me it's just naming a few concepts without explaining them. You have two questions here: 1: Does wikipedia want videos explaining subjects, 2: The content of the videos. Regarding 1: as far as I know most videos on wikipedia are to illuminate a certain concept in an article, but do not try to explain the content, just show a concept. However this question is a policy question and you should ask on the Wikipedia:Village pump. Regarding 2: we can evaluate the technical accuracy of the videos heres. Ariel. (talk) 19:59, 5 October 2010 (UTC)

I'm sorry to be critical, but I think you are putting too much emphasis on being impressive and too little on being clear. In a scientific video, there should only be one thing happening at any given moment, and it should be the thing that the audio is talking about, and the connection between sight and sound should be obvious to viewers. For what it's worth, there is at least two neuroscience articles, chemical synapse and action potential, where short videos could be very helpful to readers, and I would love to work with you on creating one if you would be interested in that. —Preceding unsigned comment added by Looie496 (talk • contribs) 16:07, October 5, 2010

Oops, thanks for signing for me, Ariel. As I understand it, the bot only autosigns for new editors. Looie496 (talk) 20:23, 5 October 2010 (UTC)

Thank you WikiDao, Ariel, Looie et al.
As a comment, these are not meant to be "finished" products but simply a sort of showcase as a "scratch and sniff" exercise. I fully realise that these clips have to be diligently researched and should either concentrate on a single matter or be published in a "drill down" method where a general overview is followed by increasingly detailed clips.
As all of the above are entirely my own work (with some marginal help from my late countryman, W. A. Mozart), I assume that legal matters should be manageable.
--Cookatoo.ergo.ZooM (talk) 20:45, 5 October 2010 (UTC)

I watched the nuclear decay one. I would dispense with the sparkles, and perhaps add subtitles for those without headphones/hearing. Neat idea, though. This could be an enormous contribution. Some of our animated GIFs of simple machines are wonderful and would presumably be improved in this format. --Sean 21:13, 5 October 2010 (UTC)

Not for me on dialup they won't. (Unless the movies are in fact smaller than the gifs they replace.) Also there is the point that not everybody has or can have the ogv plugin (if browsing on a public computer, for instance). 213.122.11.251 (talk) 22:00, 5 October 2010 (UTC)

I suspected that dialup won´t work. The files are 5 to 30 MB in size. --Cookatoo.ergo.ZooM (talk) 22:05, 5 October 2010 (UTC)

30 MB takes me roughly 2 hours. :) I am an anachronism, though. Still, mobile devices sometimes get horribly slow connections, and they're not doing it on purpose just to be awkward like I am. 213.122.11.251 (talk) 22:09, 5 October 2010 (UTC)

I just watched the "Amino acids" (also labeled "protein folding") and "DNA Packing" videos, subjects that I know pretty well. Neither was informative, both were very flashy and displayed many sophisticated animation widgets. The latter only distracted from the content, which was also inaccurate. The videos display very little sophistication in content or design, but they do demonstrate availability of tools and skill in applying those. I suggest you partner with someone who knows the content. -- Scray (talk) 23:57, 5 October 2010 (UTC)

Those look pretty but from a frankly professional point of view, I have some issues with the nuclear one.

"Nuclear fission is a reaction in which the nucleus of an atom splits into smaller nuclei, or emits other particles."

Yes, but then you go right into beta decay and gamma radiation, which are not the same thing. It makes it look like you are calling gamma radiation a form of nuclear fission. Both are forms of nuclear decay, but you don't say that in the voice over. Nuclear fission comes off as the overarching category, which it is not. This is not helped by the fact that when talking about fission, gamma decay is shown. (And alpha decay is spelled wrong.)

Frankly on the whole nuclear one I'm not sure that very much information is conveyed that would make more sense than just having it written out. The graphics are kind of generic in this respect: just some balls emitting more balls. If I were making one about nuclear fission, I'd have something a tiny bit more in depth that illustrated the following aspects, in the following order:

1. Nuclei are the heavy centers of atoms, and are a mix of protons and neutrons

2. Very heavy nuclei are often unstable

3. U-235 is unstable enough that if it absorbs another neutron, it starts to wobble

4. This wobbling can cause it to split

5. This splitting (nuclear fission) releases energy and more neutrons (recommended sound effect: a Geiger counter blip)

6. If one of these neutrons continues the reaction, it is a chain reaction (blip blip)

7. If two or more neutrons continue the reaction, it is an exponential chain reaction, like in a nuclear reactor or a nuclear bomb

8. Zoom out to show a huge chain reaction (blip blip blip blip blip)

Showing all of the above in a video might actually convey some information that is harder to convey in text or a static illustration. I would honestly not do videos for nuclear decay in general — the video just doesn't add anything, doesn't help you visualize it any more than a static illustration. I would also drop the music, which sounds pretentious to my ear. Putting classical music with anything scientific just makes it sound like it takes itself too seriously.

From a general point of view, the goal of a video explanation is to do something better than what you can do in text or a static diagram. That means something where the inclusion of movement and sound materially improve the final product. In some cases this is obvious: a video of a parrot talking conveys so much more than a photograph or a textual description ever could to someone who has never heard a parrot talk before. In some cases, this is important but less obvious: a video of a machine working intuitively shows us how things go together better than a set of static diagrams. But in a lot of cases this does not help: it just becomes a way to read or display something that is already well-represented in text or static illustration. Your trick is to figure out what's the best use of your time in this respect, what really would improve the article and not just be an illustrated reading of it. For nuclear fission, things that are hard to convey in diagrams include things like the wobbling or the speed of a big chain reaction (exponential growth is a hard thing for most people to grok, I have found). So a video which had those in it would be useful.

I'm not trying to be overly critical here, just trying to give some constructive criticism. --Mr.98 (talk) 12:02, 6 October 2010 (UTC)

The Ref Desk is not the place for reviewing video work in progress, which is like an article content discussion. I suggest that you A) place your videos on a video server and in a format that is as quick and universally accessible as possible. Would YouTube and FLV work for you? Then B) send a note to some editors that have been active on the relevant Wikipedia article (see its history) personally or on the article discussion page saying you would welcome their comment on a particular video. Cuddlyable3 (talk) 12:14, 6 October 2010 (UTC)

It's not a bad place though to get collaborative feedback. This is not just about article content editing, and it's broader than the content of the article (it's about presentation more than it is content). --Mr.98 (talk) 12:16, 6 October 2010 (UTC)

I think that these videos need to be improved to be useful for the reader

• I think it's very important to avoid extraneous elements in the videos. For example, the first video throws a gaggle of spheres at the video; the second has a sphere moving down the middle of the DNA for some odd reason; the third has some kind of waves around the nucleus (unless they're supposed to be orbitals? but the "electrons" are then closer).
• It's going to be very easy to end up with technical quibbles about the content shown. For example, the demonstration of DNA winding around nucleosomes shows a free end moving all over the map. But in DNA there's practically never a free end - it has to wind around them in place. So it'll take some doing to get a video that seems right to everyone.
• I just can't believe how slowly these videos load. Despite being thumbnail-sized and only a minute long, they're exasperating to load on a cable connection that has no trouble with the standard YouTube fare.

In general, I find myself more interested in how you made these videos, and I think that until we get the making of such videos into a common collaborative space, it'll be hard to make them optimal resources. As they say, give a man a fish and he has a meal for a day, but teach him how to fish and he can permanently deplete the natural resource. Wnt (talk) 16:07, 6 October 2010 (UTC)

They are not thumbnail-sized, they are 720x540. However they are somewhat undercompressed. They have 192 kbit audio, when they probably only need 32 kbit. The video compression seems fine though (although it could go a somewhat tighter). To the uploader: Reduce the audio bitrate because for speech and background music you don't need high quality, then do two encodes: and low bitrate video (i.e. compress just to the point of visible blocking), and a higher quality one. Ariel. (talk) 19:51, 6 October 2010 (UTC)

I should have made it clear that these were not meant to be serious scientific / finished video clips, as I am not a scientist. They are meant to be experiments (simplistic and partly incorrect due to my lack of knowledge) which show what can be done.
Clearly, compiling a scientific clip would require cooperating with experts in the relevant field and significant communication to arrive at a useful final product.
I am basically asking if editors in scientific areas have an interest in such a teamwork to make video clips available to WP users. Thanks to everybody who has answered. --Cookatoo.ergo.ZooM (talk) 07:30, 7 October 2010 (UTC)

I think that yes, there's interest in such a teamwork. But in order to function well as a team, editors will need to know more — what the software is, how objects are created and simulated in it, what the difficulty level is. By posting the five videos you give the impression it's a rather off-the-cuff process, yet it looks like it must have been very complicated to set up... how long did it take to make one of these? Editors should know how the video is made so they know what information to specify and what is involved in following through with a request, making a change, etc. Wnt (talk) 13:20, 7 October 2010 (UTC)

The 3D modeling software used is Cheetah 3D (as I am a Mac user of the above mentioned little brain). The generated .mov documents are imported into iMovie, fitted with titles, optional music (via iTunes) and optional voice over (via GarageBand). iMovie allows various export modes, depending on the resolution required. Clearly, the size of the resulting files (and the response via accessing those in WP) differ. The generated m4v documents are then recoded to .theora.ogv documents as per WP file upload requirements. The time for creating (and rendering) a video clip varies widely. If there are preexisting models (for a neuron, an atomic nucleus, etc; they accumulate naturally during modeling), it may be a matter of some hours. If a model has to be build from scratch (eg a human heart for a simulation) this may be days. Of course, the rendering also depends on the hardware deployed (iMac 27 inch, i7). Architectural renderings (with glass, steel and other reflective surfaces, complex lighting and materials etc. may be 12 hours or more). The attached video clip, 8.4 MB, on chemical synapse (designed in cooperation with a WP editor with a neuroscience background) has been created today between 15:00 (3 PM) and 24:00 (midnight), which makes 9:00 hours. This is work in progress and still has to be modified / improved according to the specs of the aforementioned editor. --Cookatoo.ergo.ZooM (talk) 22:15, 7 October 2010 (UTC)

Is E=mc^2 an approximation?

Here http://www.fourmilab.ch/etexts/einstein/E_mc2/e_mc2.pdf the formula just prior to E=mc^2 is obtained by "Neglecting magnitudes of fourth and higher orders". Would E=mc^2 be different if you did not ignore fourth powers and above? Say you went up to tenth powers for example? I claim my Nobel Prize. 92.29.115.43 (talk) 19:11, 5 October 2010 (UTC)

No: those terms are relativistic corrections to the kinetic energy, and Einstein's point is that the kinetic energy changes (never mind its precise value). He uses the convenient, low-speed case where the classical formula applies, but the full formula works if you also include the Doppler effect in the energy of the light emitted. --Tardis (talk) 19:28, 5 October 2010 (UTC)

Celebrity endorsement - scientific name of?

What is the name of the psychological or sociological process(es) involved in the celebrity endorsement of a product? Its not peer pressure, since the celeb is not a peer. Thanks 92.29.115.43 (talk) 19:38, 5 October 2010 (UTC)

Social climbing? Bus stop (talk) 19:43, 5 October 2010 (UTC)

It sounds like you are referring to the logical fallacy called Appeal to Celebrity. Interestingly, the Wikipedia article listing Fallacies does not include it. Somewhat related though is Argumentum ad populum and Argument from authority. --Zerozal (talk) 19:48, 5 October 2010 (UTC)

Ad hominem#Inverse ad hominem Hcobb (talk) 19:52, 5 October 2010 (UTC)

Association fallacy? Clarityfiend (talk) 20:56, 5 October 2010 (UTC)

But surely "peer pressure" does apply? Are you saying, OP, that celebrities have no peers? Since obviously they do, then in fact: yes, that pressure is likely to apply here in the same way that it applies in any other situation. WikiDao ☯ (talk) 22:13, 5 October 2010 (UTC)

Its not peer pressure, since the celeb is not a peer of the person being influenced. 92.28.240.84 (talk) 22:51, 5 October 2010 (UTC)

Oh, I see. (There was a question not long ago about why celebs engage in "charity work" – I mistook your question to be about that, which does involve peer pressure).

The "Measuring the use of celebrities in marketing programs" section of the "Celebrity endorsement" article says that ad people use some metric that "enables advertisers and ad-agency personnel to determine if a particular public figure will motivate consumers who see them in an ad to purchase the product advertised." And you are asking why that happens, right? And that's a good question; I'll give that some thought. Sorry for the misunderstanding :) WikiDao ☯ (talk) 23:16, 5 October 2010 (UTC)

Argument from authority is probably the most spot-on logical fallacy, though the psychological reasons we find celebrities to be "authorities" in these contexts are surely more complicated than a logical fallacy can explain. I think most people are savvy enough on a rational level to say, "Just because Tiger Woods golfs in an ad for a mutual fund, doesn't mean that the mutual fund is any good, just that it has a large ad budget." But on a psychological level, these kinds of ads do seem to work pretty well — branding does matter a huge amount, and celebrities are a large part of that. It's too bad our own celebrity endorsement article is so anemic, as I am sure there has been good work done on this by psychologists, media studies people, business people, etc. Boorstin's The Image has a lot on the rise of celebrity endorsements as a form of advertising, if I recall. --Mr.98 (talk) 13:20, 6 October 2010 (UTC)

Ethanethiol production

Can ethanethiol be made by reacting hydrogen sulphide with ethanol? Like this:
H₂S + CH₃CH₂OH → H₂O + C₂H₅SH
--The High Fin Sperm Whale 20:45, 5 October 2010 (UTC)

Fixed formula for ethanol, if you don't mind. (A CH₄ cluster would be it's own methane and not attached by any strong bonds.) Hcobb (talk) 21:34, 5 October 2010 (UTC)

Yes, but the reaction is slow. It is more normal to use a basic environment to deprotonate the hydrogen sulfide, which speeds up the reaction:

HS⁻ + CH₃CH₂OH → OH⁻ + C₂H₅SH

Physchim62 (talk) 22:00, 5 October 2010 (UTC)

I suspect that would lead to an equilibrium that favours the ethanol. Or the creation of diethyl ether -- the sulfur would act as a nucleophilic catalyst. (basically the sulfide may be a good nucleophile -- but it's also a good leaving group. there are some similarities to potassium iodide.) Unless in a protic solvent deprotonated sulfide is a stronger nucleophile than hydroxide? :Another possibility is triethylamine + ethanol + hydrogen sulfide, but here you again risk making diethyl ether. There are some reagents that will convert the -OH group to a good leaving group but it's much cheaper to start from ethylene instead! John Riemann Soong (talk) 00:16, 7 October 2010 (UTC)

Although, since ethanethiol has a lower boiling point than ethanol, run the reaction with base carefully at about 65-75C. The ethanethiol will boil off and you can collect it in a distillation flask via Le Chatelier. I am not sure if you want it to actually run it in mostly ethanol or whether you want a strong polar (and protic) solvent like water or even formamide (will DMF work?). I didn't know sulfide could displace hydroxide leaving groups, but maybe if the hydroxide is more strongly coordinated than the sulfide, it isn't such a terrible leaving group kinetically. John Riemann Soong (talk) 00:44, 7 October 2010 (UTC)

Why do parrots mimic human speech?

Why do parrots mimic human speech? The article at Talking birds only provides a list of birds that do this, without explaining the phenomenon. 86.161.31.85 (talk) 21:32, 5 October 2010 (UTC)

Bird vocalization#Learning All bird songs are learned. Hcobb (talk) 21:37, 5 October 2010 (UTC)

Probably because many parrots are domesticated, and those that are learn to "speak" words in the language of the human for communication. ~AH1^(TCU) 23:57, 5 October 2010 (UTC)

Some birds mimic sounds in their environment, and particularly unusual sounds. This may be to attract and impress prospective mates. I recall a TV documentary narrated by Sir David Attenborough in which a forest-dwelling bird did a spectacular impersonation of a chain saw, and another bird mimicked the click of a camera shutter! Mimicking of human speech occurs simply because human speech is an unusual sound in that bird's environment. Dolphin (t) 01:45, 6 October 2010 (UTC)

Northern Mockingbird are attested to mimic car alarms, among other urban sounds. It is mentioned, but uncited in the article, but running a google search on "mockingbird car alarms" will turn up plenty of anecdotes and even a few videos. --Jayron32 01:54, 6 October 2010 (UTC)

Throughout each summer, I witness the "car alarm" birds every morning. I think it is especially prevalent with the mocking birds around my house because I live two blocks away from the "auto mile" - over a mile of car lot after car lot. -- kainaw™ 11:40, 6 October 2010 (UTC)

@Dolphin51: The bird in question, for both the camera sounds and the chain saw (and a car alarm, and an auto-focus camera, and...) is the Superb Lyrebird, from the sixth episode of Attenborough's series, "The Life of Birds". Matt Deres (talk) 14:12, 6 October 2010 (UTC)

Thanks Matt. That's the one. Dolphin (t) 21:37, 7 October 2010 (UTC)

When a bird mimics human speech it gets lots of attention and affection from its master, which may be rewarding to a bird, thereby increasing the frequency of the bird emitting the operant. See Operant conditioning and the older Law of effect. Edison (talk) 04:07, 6 October 2010 (UTC)

Youl'll find more about mimicry in our article on perhaps the best vocal mimic of the bird world - the Lyrebird. Mattopaedia ^{Say G'Day!} 08:22, 6 October 2010 (UTC)

The Wikipedia article Parrot notes that the question why parrots imitate sounds is open. I have assumed they do it to deceive predators that one is of the same species or to deceive prey that one is not a predator. However the article cites only one parrot breed that is observed imitating other birds, and the article Talking bird says an Arielle Macaw speaks coherently enough to disprove the cliché “Parrots just imitate what they hear”. Still speculating, a parrot in the wild may communicate sounds that it has heard elsewhere to other parrots in the same way as a bee communicates its floral findings to other bees by means of a special dance. There are various jokes about embarrassing dialogs reiterated by parrots. Cuddlyable3 (talk) 11:40, 6 October 2010 (UTC)

It's worth noting that parrots can figure out the right context for certain words. I know of parrots who know to say "hello" when someone new enters a room, to say "shut up" when there is a loud noise, and to say "bad bird" when they are doing something that they know is against the rules. —Arctic Gnome (talk • contribs) 05:14, 7 October 2010 (UTC)

5' on sense strand corresponds to C or N terminal on protein?

For 500 points: 5' on sense strand corresponds to C- or N-terminal on protein? --178.98.126.128 (talk) 22:18, 5 October 2010 (UTC)

Have you looked at Sense (molecular biology)#Antisense_DNA?Smallman12q (talk) 23:00, 5 October 2010 (UTC)

Yipes! Even knowing the answer a person couldn't figure it out from that article.

• First, mRNAs are always translated from 5' to 3' — this is the way that ribosomes work in all organisms, and I truly mean all organisms capable of making proteins as directed by a nucleic acid; in many organisms mRNA is first recognized at a special 5' cap.
• Next, translation always, and I mean always, adds amino acids to the C-terminus of a protein chain. (there's also a special fMet structure in bacteria, which should remind you that you don't have a free NH2 to play with even if you were so minded) I should note that this is true even for nonribosomal peptides and polyketide synthase. All these processes, including preparation of amino acids by aminoacyl-tRNA synthetase,[18] involve a common step where the -SH group of coenzyme A (or at least pantetheine) binds to the C-terminal spot of the protein, peptide, or polyketide — you're actually seeing an aspect of how life functioned before the 'invention' of proteins with CoA at the C-terminus ready to act as a leaving group as each new component is added there.

For these reasons, it is always 5' to 3' codes N to C, with proteins synthesized in that direction by addition to the free C terminus. Wnt (talk) 14:06, 7 October 2010 (UTC)

"treated merino wool

what is "treated merino wool" what do they treat it with. ie. smart wool —Preceding unsigned comment added by Kj650 (talk • contribs) 23:35, 5 October 2010 (UTC)

It is more a case of Smartwool treating Merino wool. Obviously, I can't tell you what the secret process is, otherwise you could copy it and become rich beyond your wildest dreams, which may coarse you to become very unhappy and sad. But fulling process does not involve the usual treatment with chlorine... Oh dear! Have I let the cat out the bag and kicked over the pot?--Aspro (talk) 00:43, 6 October 2010 (UTC)

Interestingly, several of the properties claimed for "Smartwool" are possessed by merino wool anyway - non-itch, moisture-wicking, and odour-reducing. Indeed, apart from the non-itch, all wool is like this. DuncanHill (talk) 01:02, 6 October 2010 (UTC)

Merino wool isn't itch free. I'm not saying smart wool is any better in this regard but I know people who do find merino wool is still itchy even if not even close to being as bad as normal wool Nil Einne (talk) 07:04, 6 October 2010 (UTC)

Personally, I don't find any wool itchy. DuncanHill (talk) 13:33, 6 October 2010 (UTC)

do they treat it will perm press chemicals? —Preceding unsigned comment added by Kj650 (talk • contribs) 01:52, 6 October 2010 (UTC)

I doubt anyone here knows how the specific wool you are referring to has been treated, particularly given we don't even know what product or brand you are referring to, where you bought it etc. If you have concerns, I suggest you ask the manufacturer of the product what they used to treat the wool. Nil Einne (talk) 08:58, 6 October 2010 (UTC)

The Wikipedia article Wool notes that Wool treated with lanolin is water resistant, air permeable, and slightly antibacterial, so it resists the buildup of odor. It is also possible to make wool washable by treating the fibers by removing their "scales" or by coating with a polymer, see the cited article. Such wool is used for wool socks[19]. There is a collection of articles about wool here (it includes the Wikipedia article) that gives more information on wool production. Cuddlyable3 (talk) 09:53, 6 October 2010 (UTC)

Wool treated with lanolin? So they put back the lanolin they've already removed from the wool? Wool is washable anyway, you just need to use a low temperature and a gentle soap rather than a biological detergent. DuncanHill (talk) 13:33, 6 October 2010 (UTC)

October 6

change in ic engine

how we can change petrol ic engine to disel ic engine? —Preceding unsigned comment added by 210.212.170.226 (talk) 09:52, 6 October 2010 (UTC)

Not easily. A Diesel engine has needs higher compression to ignite its fuel instead of using a spark plug. External heating or adding kerosene will be needed to start a diesel engine in cold weather, its power-to-weight ratio is worse, its speed range is low, and it produces unhealthy black smoke particles unless a special filter is fitted. Cuddlyable3 (talk) 10:08, 6 October 2010 (UTC)

On the other hand, the thermodynamic efficiency is higher, practical efficiency is further boosted because the fuel has a higher energy density, the engine is more robust, it delivers more torque at low revs, and the power-to-weight ratio is plenty good enough for e.g. BMW to offer Diesel engines for a wide range of models marketed towards performance-oriented drivers. At least in Germany, Diesel engines are the first choice for people who drive a lot (Diesel models are more expensive, as is vehicle tax, but Diesel fuel is cheaper and mileage is better - there is a cross-over somewhere between 10000 km/year and 30000 km/year). I agree that there is no practical way of reconfiguring standard petrol engines as Diesel engines. However, there are some new engine concepts that essentially amount to a Diesel cycle with petrol as a fuel - see Gasoline direct injection.--Stephan Schulz (talk) 14:44, 6 October 2010 (UTC)

Is there a differential in the tax imposed on the fuels in Germany? In the UK, diesel fuel is more expensive. Dbfirs 23:03, 6 October 2010 (UTC)

(edit conflict) It would be very difficult to convert an engine from petrol to diesel, as the two types of engine are very different, despite both being called internal combustion engines. A diesel engine does not use a spark plug to ignite its fuel - it uses the heat created by the compression stroke. As a result, a diesel engine needs to have a much higher compression ratio than a petrol engine. It may also need a mechanism for pre-heating the engine block or the air intake when starting in cold weather. A car can be converted from petrol to diesel, but this involves completely replacing the engine. Gandalf61 (talk) 10:14, 6 October 2010 (UTC)

Could diesel fuel be ignited with the spark plug, thereby reducing the needed compression?Edison (talk) 19:34, 6 October 2010 (UTC)

Not really. Diesel fuel under lower pressures produces MUCH less explosive force than does gasoline. The higher compressions are required not only to ignite the diesel, but also to generate the forces necessary to actually run the engine. If you tried to burn diesel in a gasoline engine, it wouldn't generate enough energy to keep itself going. Part of the genius of diesel engines is the ability to use a wide range of lower-energy fuels. You can make diesel from a wide variety of sources, not just petroleum (see biodiesel) and, with small modifications, you can actually run a diesel engine on straight vegetable oil, like the stuff you buy in the grocery store, see Vegetable oil fuel. In that way, diesel engines are much less "finicky" than gasoline engines, which require a fuel of a very specific burning profile, and require carefully timed sparking system to control the burn just right. With diesel engines, if its a liquid and it burns, you can probably run the engine on it, at least in the short term. Of course, certain substances would produce too much soot, and would gum-up the engine, but you really can run a diesel engine on just about anything. See Diesel_engine#Fuel_and_fluid_characteristics for a bit more. --Jayron32 05:28, 7 October 2010 (UTC)

I have read somewhere that some military vehicles can run on Diesel, gasoline or jet fuel, but I don't recall the vehicle, which country made it or if the capability was limited to emergencies and would shorten the life of the engine. Googlemeister (talk) 13:12, 7 October 2010 (UTC)

Atlantic halibut

Why is it called hippoglossus ("horse-tongue")? DRosenbach ^{(Talk | Contribs)} 16:51, 6 October 2010 (UTC)

Hippoglossus says "a reference to the shape of the fish". (Why are these separate articles?) 213.122.67.69 (talk) 17:04, 6 October 2010 (UTC)

One is about a species and one is about a genus. --The High Fin Sperm Whale 18:11, 6 October 2010 (UTC)

Planet gravity

If we assume that Gliese 581g is 3 times heavier then Earth, and have same density, what "gravity force"(or whatever it called, excuse my English) would be on the planet? My first estimation would be cubic square from 3, so ~1.45 bigger then on Earth, 9.81 m/s2 * 1.45 = 14.22 m/s2. Am I correct? Or increased volume(*3) would slightly decrease that number? 76.67.8.211 (talk) 19:49, 6 October 2010 (UTC)

Your number is correct, but I'm not sure it is correct for the right reason. Gravity is proportional to M/R². M would increase by a factor of 3, R by a factor of the cube root of 3. Plug these in and you get gravity increasing by a factor of cube root of 3. Looie496 (talk) 20:00, 6 October 2010 (UTC)

The term that OP was looking for is gravitational acceleration. --Wrongfilter (talk) 10:14, 7 October 2010 (UTC)

Cleaning detergents

There are dozens of different brands of detergents for household cleaning. Some are designed to be diluted with hot water, others are sprayed. Are they basically all the same apart from colouring and fragrence, or do some have different ingredients that truely make them better than other brands? In other words, is the supermarket own-label likely to be just as effective as more expensive brands? Thanks 92.29.127.126 (talk) 19:52, 6 October 2010 (UTC)

You'd have to look at the label of each product, and tease out the "active ingredients" from them to know how each worked before deciding to rank cleaning products by effectiveness. It should also be noted that some cleaning products work better in some applications, but not in others, so there is no "one-size-fits-all" detergent. The Wikipedia article Detergent presents an overview, and lots of blue-links to different classes of detergents. Some of these may be used in different proprotions in different products, while sometimes cleaning products are incompatable for safety reasons (never mix ammonia and bleach, for example). --Jayron32 19:59, 6 October 2010 (UTC)

You may also want to invest in the magazine Which? or check out their website. They often do this sort of comparison of products. ny156uk (talk) 21:05, 6 October 2010 (UTC)

The point is that the list of ingredients all look similar or identical across the brands. In the UK you only get one or two things listed. The ingrediants list of two near at hand detergents I have are -

Fairy Liquid: 15-30% anionic surfactants, 5-15% non-ionic surfactants, methylisothiozolinone, phenoxyethanol, perfumes.

Elbow Grease: Less than 5% non-ionic surfactants, cationic surfactants, phosphate, perfume, limonene.

Fairy Liquid is a washing-up liquid. Elbow Grease is a spray on household cleaner. It says "All puropose degreaser" on the bottle, but isnt any detergent a degreaser?

Is Elbow Grease no more than just a very watered down version of Fairy Liquid?

(I got some wet gloss paint on my clothes. I smothered it in neat Fairy Liquid, then rubbed it under a tap - to my surprise it disapeared completely.) 92.24.183.150 (talk) 23:12, 6 October 2010 (UTC)

The challenge is providing an emulsion system for solvation of grease without dissolving or attacking your hands. Quaternary amines are usually seen as powerfully strong, so they are avoided. (Those are cationic surfactants.) They are also capable of penetrating cell membranes, whereas anionic surfactants can't. I wish they had a househould equivalent of acetone (30% concentration maybe) -- I get it on my hands so often in the lab I am sure that if you wash it off immediately it's MUCH more of a convenience than household detergent, and it doesn't oxidise like bleach. John Riemann Soong (talk) 02:31, 7 October 2010 (UTC)

Is there any consumer guide to the different types of household detergents that I could read? Thanks 92.28.245.77 (talk) 12:58, 7 October 2010 (UTC)

My guess is, that own-label washing powder diluted with hot water should be as effective as any other detergent, and a fraction of the cost. 92.15.10.67 (talk) 19:44, 7 October 2010 (UTC)

Microfibre cloths for cleaning

Are microfibre cloths truely better at cleaning surfaces than rubbing with ordinary cloths, or are they just a gimmick? I've read the article. Thanks. 92.29.127.126 (talk) 19:54, 6 October 2010 (UTC)

What makes microfiber cloths useful is two things: 1) They are less likely to scratch the surface you are cleaning than an ordinary rag. and 2) They have a particular distribution of pore space that makes their absorbant properties useful in holding dirt. Whether these are important factors for you in deciding to spend money on them is, of course, entirely up to you. --Jayron32 20:02, 6 October 2010 (UTC)

"Better" depends on what you're cleaning and how much time and money you have to spend on cleaning it. As Jaron explains, they're not just a gimmick, but neither are they a 'cleaning panacea'. If you need to rub hard, then microfibre cloths are probably no better than the average rag, but that doesn't mean there aren't people who find them useful for lighter cleaning. Physchim62 (talk) 20:26, 6 October 2010 (UTC)

My experience with microfibre cloths is that they are very good because they don't chafe and leave lint. This is particularly attractive for wet cleaning glass such as mirrors and motor vehicle windshields. Dolphin (t) 22:11, 6 October 2010 (UTC)

I can add my anecdotal support. They work well for me! Mattopaedia ^{Say G'Day!} 04:30, 7 October 2010 (UTC)

The theory of toxic sludge lagoons, re: Hungary's red flood

News stories such as [20] and the article Ajka alumina plant accident state that an aluminum plant pumped waste products into a "sludge reservoir" for 25 years. Eventually the reservoir wall collapsed and the sludge, said to have a pH of 13, and to contain some radioactive metals and toxic heavy metals, leaked over the countryside, killing a number of people. What was the theory behind storing the waste in a reservoir? Was some natural process supposed to eventually detoxify it, such as by lowering the pH? Do chemical plants in some jurisrdictions have to treat the waste products on an ongoing basis, such as by using something acidic to neutralize the waste? Was the idea that someday someone else than the aluminum plant owners would set up some process to detoxify the material? Was it assumed that it could just be stored forever in the reservoir, perhaps by somehow drying it and putting plastic or clay over the top?How would it become dry if it is in an open reservoir? Does some Wikipedia article cover the general topic of sludge reservoirs other than sewage sludge? Edison (talk) 22:26, 6 October 2010 (UTC)

According to this source listed in the red mud article, basically they put it into a reservoir just to serve as a landfill: no theory that it would ever naturally clean up, or even necessarily be cleaned up by the company, just an isolation of waste. Bleck. --Mr.98 (talk) 22:49, 6 October 2010 (UTC)

There is a natural process that lowers the pH: the absorption of carbon dioxide from the atmosphere. The company involved in Monday's accident says that it covers its disused sludge ponds with "soil and plants" (make of that what you want). Otherwise, there's not much theory behind it, it's just something that's been done for the last 130 years in the alumina industry. Physchim62 (talk) 22:54, 6 October 2010 (UTC)

Disposal of carbon dioxide is a major problem in relation to global warming. Is reaction with red mud a way to sequester a lot of carbon dioxide while making the red mud less toxic? How come the book cited above says it is not an environmental hazard? Edison (talk) 23:04, 6 October 2010 (UTC)

The scales are not anywhere near close. It would take upping the production of alumina waste several thousand times before you made a reasonable dent in terms of carbon sequestration. --Jayron32 01:26, 7 October 2010 (UTC)

Back to the OP's question, part of the idea of these sludge ponds is to essentially keep all the wastes and toxins in one location, rather than spreading them around the countryside, rather like any waste dump but with the added threat of toxins getting out. I live near the operations of fairly extensive gold mining from the mid-late 1800s to early 1900s. Large amounts of toxic waste, largely cyanide wastes from the gold cyanidation were initially dumped in the waterways, and then when at some point they realised that wasn't such a good idea, they started collecting them in these sludge ponds. The remains of the ponds are still there - not much grows on them and they are not even fenced off, but there are warning signs. There is a type of crust that has formed on the surface which means they don't blow or wash away or anything, and the general wisdom is that as long as you don't break the crust they're generally pretty safe. There are people that live reasonably close to the most obvious dumps, say within about 1/2 to 1 km, and they don't show any obvious signs of cyanide poisoning or shortened life spans. --jjron (talk) 07:49, 7 October 2010 (UTC)

October 7

using sulfur to make carbon-carbon bonds

Are there any examples where for example, a sulfide attacks an electrophilic position to make some sort of cyclic intermediate or transition state, but then the intermediate/TS rearranges to eliminate the sulfur (maybe as an alkyl rearrangement). It doesn't necessarily have to leave the molecule, just make a new C-C bond.

i.e. RS- + R'X ---> R-S-R' + X- ---> R-R' [X is just an EWG, doesn't have to be halide or technically leave]

I see some interesting results from the Edman degradation reaction -- how does the sulfide leave the ring? Is this principle used in an any economically important drug syntheses?

Another route that I can see is to start from a sulfone and then make it possible for the sulfone to leave as sulfur dioxide.

I've not taken orgo III so I don't know the general principles of rearrangement reactions. They are rather mystifying to me. John Riemann Soong (talk) 00:23, 7 October 2010 (UTC)

One of the most common internal rearrangement reactions occurs in carbocation formation, such as you would find in an SN1 or E1 mechanism. See Rearrangement reaction for a general overview of different types of common rearrangements. There's lots of blue links to follow for additional details. Also, forming carbon-carbon bonds is often done via Organometallic chemistry which results in the formation of a carboanion. The key in forming carbon-carbon bonds is making the carbon a nucleophile. Common ways of achieving this are via Grignard reagents, Organolithium reagent, etc. The carbon-sulfur bond is fairly non-polar, and things like sulfone result in carbocations (electrophilic) (assuming SN1-type leaving groups). In fact, thiols make FANTASTIC leaving groups, so the positive part of the reaction can be a thiol. However, you'd still need a good nucleophilic source of carbon, and you are pretty much back to organometallics there. --Jayron32 01:40, 7 October 2010 (UTC)

There are no organometallics in the Edman degradation! I'm aiming for slightly milder conditions than superbases like Grignards and organolithiums. Do sulfones not interconvert into the tautomeric equivalents of enols?

Also, something with a small number of steps (I believe organometallic reactions are frequently tedious?) and an "elegant" rearrangement (to me, the Edman degradation is "elegant") I guess is what I had in mind. What is the general principle in the final rearrangement in the Edman degradation? John Riemann Soong (talk) 01:50, 7 October 2010 (UTC)

Sulfones can be deprotonated at the adjacent carbon (pKa ~ 30), but typically amine-bases like LDA or more commonly n-BuLi are used. It's not quite the same effect as an enolate because a sulfone isn't exactly an S=O bonding like a carbonyl C=O. You can deprotonate α to a sulfoxide, 5ish pKa units less acidic, and even at a position α to two thiols (not oxidized) in the same range as those two--definitely no resonance in that case. You can sure think of it that way and use the analogy to explain this sort of reaction though. DMacks (talk) 02:07, 7 October 2010 (UTC)

Ramberg–Bäcklund reaction. DMacks (talk) 01:51, 7 October 2010 (UTC)

Thanks! What is the usual pka of the C-H bond alpha to a sulfone? Can this pKa be lowered with an alternative choice of solvent to water (or a Lewis acid)? Do you really need a superbase to deprotonate it? John Riemann Soong (talk) 02:11, 7 October 2010 (UTC)

Those pKa are from DMSO...would be hard to measure such high pKa in water I assume. As with anything pKa, changing "what else" is attached to the position being deprotonated can have a large effect--here again enolates are a good comparison for a similar pattern. You can also change the electronegativity of the "other side" of the anion-stabilizing group. Here's some approximate pKa values (in DMSO) for the α-CH in various structures:

Ph-E-CH2-R E↓    R→ H Ph CO 25 20 SO2 29 23.5

E'-E-CH3 E↓    E'→ Ph CH3 CF3 CO 25 26.5 ? SO2 29 31 19

You can also add electron-withdrawing groups to the Ph, but probably only gives you a decrease of 2–3 pKa units.DMacks (talk) 18:12, 7 October 2010 (UTC)

The Eschenmoser sulfide contraction is also a reaction that's similar to that which you're talking about. Physchim62 (talk) 12:07, 7 October 2010 (UTC)

It doesn't seem as popular as it should for its utility. I mean the reagents look cheaper than a lot of expensive organometallics. John Riemann Soong (talk) 16:10, 7 October 2010 (UTC)

3-second Pop Tarts?

On my box of Pop Tarts, it says "Microwave on high setting for 3 seconds". But if I microwave them for such a short time, it has hardly any effect, and the Pop Tarts remain cold. I've seen many other people comment on this online, and I know that there's nothing wrong with my microwave. So why is there such a blatantly wrong instruction on the box? Were they sued by someone whose Pop Tarts burst into flame after 5 seconds? --140.232.178.74 (talk) 01:05, 7 October 2010 (UTC)

Presumably, that's so the Kellogs corporation ends up on the safe side of this: [21]. Admitedly, this is a toaster, and not a microwave, but I still wouldn't want to end up on the wrong side of that. --Jayron32 01:18, 7 October 2010 (UTC)

...sulfuric acid costs 9.8 cents a litre

(Average rate, from dividing 8 billion dollars by 165 million tonnes and factoring in the density of H2SO4.) I know there's economy of scale and all, especially when it comes to safe delivery....but why then does it cost a 100 bucks to order a 2.5L bottle of 95% sulfuric acid from Sigma-Aldrich? That's about 400 times more expensive. John Riemann Soong (talk) 01:10, 7 October 2010 (UTC)

So, do you have your own Winchester bottle you are going to drive up to your local sulfuric acid manufacturer, and ask them to top off for you? It isn't like the local dairy farm, where you can get your milk from the source on the cheap, and you don't really buy the stuff wholesale, unless you are buying a LOT of it. The cost/liter is the cost of production, and does not factor in the costs associated with the transport, containment, and distribution of the substance. The same sorts of cost inflation occurs for every product made on an industrial scale. While the price you pay is often several hundred times more than the cost of the materials to make a product, it isn't like the company makes up the difference in pure profit. There are LOTS of people to pay along the way. --Jayron32 01:24, 7 October 2010 (UTC)

I just didn't expect the ratio to be so high. I'm sure the ratio for industrial meat (which has mega food safety concerns) versus consumer/supermarket meat doesn't exceed an order of magnitude very often... John Riemann Soong (talk) 01:34, 7 October 2010 (UTC)

It isn't just safety that drives up cost. Its how many hands are in the pie that does. You have to pay all the people between you and the factory that makes the sulfuric acid, that means all the employees of those companies, including the receptionists and the accounants and the janitors and everyone else takes a cut along the way, in every single company. The chain involved in getting a T-bone steak to your table is actually a lot shorter, since the grocery store you buy it from probably gets it straight from the slaughterhouse. --Jayron32 01:43, 7 October 2010 (UTC)

Here's an interesting article on the sulfuric acid market: [22], and another one from last year [23]. Evidentially, there's been some recent volatility in the market. It does seem surprising that it costs $100 bucks for a couple kilos, though to be fair, the 10 cent/L value was from 2001, and it appears that $400/tonne is more in line with what producers want (though it was depressed in 2008, and I'm not sure how it's doing now). I agree, $35 a Liter, or whatever, does seem like a pretty steep markup. I suppose that the stuff used to make fertilizer probably isn't pure enough to use in a lab, so I'm not sure what type of markup you'd expect there to get lab grade stuff over industrial "good enough" grade. Buddy431 (talk) 03:41, 7 October 2010 (UTC)

Chemical economics! The supply of sulfuric acid is inelastic? wow. John Riemann Soong (talk) 03:57, 7 October 2010 (UTC)

Isn't that roughly what one would expect, since demand will be almost constant, at least for the scientific grade. Dbfirs 07:33, 7 October 2010 (UTC)

Did you read my articles? The demand for Sulfuric acid is not constant; it rises and falls with the demand for phosphate based fertilizer, its main use. The amount of acid used in a lab is tiny compared to that used in industrial processes, especially the making of fertilizer. Additionally, the price of Sulfuric acid is influenced by the price of Sulfur, which does have a more variable supply as old mines are used up and new ones built. Buddy431 (talk) 13:27, 7 October 2010 (UTC)

The supply of bulk chemicals is very inelastic, because the factories cost so much to build and, once they're built, cost so much to keep idle. Physchim62 (talk) 08:28, 7 October 2010 (UTC)

err, if demand is constant, then elasticity of demand is inelastic. I mean for normal bulk chemicals, I assume if costs plunge or drastically rise factories can allocate good as necessary. They might decide to make perchloric acid instead for example. John Riemann Soong (talk) 09:33, 7 October 2010 (UTC)

Also consider quality. I very much assume that the 165 million tonnes is not lab-quality sulfuric acid. Compare water. You can get it for free from every major ocean, but if you want the refined version in your super market, Evian charges several reasonable currency units per bottle. --Stephan Schulz (talk) 07:57, 7 October 2010 (UTC)

Most sulphuric acid is very cheap for the reason that most it is produced as a waist product. If you buy non-analytical (which is made by another process in order to maintain purity) industrial acid then is is a lot less.. See Drain cleaner A reasonable mark up for a hazardous product. It is about the same price as this per litre, here in the UK.--Aspro (talk) 08:20, 7 October 2010 (UTC)

As a VERY rough approximation, the price of a laboratory chemical goes up by an order of magnitude for each extra "nine" you want on the purity! Also, if you compare catalogues, you'll see that Sigma-Aldrich are quite expensive as a supplier: they can charge more because of their reputation, and because of the convenience of being able to get just about everything from one place. Physchim62 (talk) 08:32, 7 October 2010 (UTC)

Slit diffraction

When light passes through a slit via Huygens–Fresnel principle, there are waves that encounter the walls of the slit, yes? Does it make a difference whether the walls of the slit absorb or reflect the waves? John Riemann Soong (talk) 04:32, 7 October 2010 (UTC)

I'm also trying to understand the diffraction limit in microscopy -- it's purely due to what happens at the lens, right? That is, if I'm trying to image a 70 nm nanoparticle, we don't have to worry about the interference pattern from the light hitting a rough surface or the reflection pattern of the light hitting a bunch of closely-spaced nanoparticles and we aren't treating the imaged objects as apertures? John Riemann Soong (talk) 05:18, 7 October 2010 (UTC)

I think the you should treat the imaged objects as apertures. I do not think the composition of walls of the slit have any impotrance. A ideal slit is of zero length so the walls i am talking about are tha walls facing the source. If the slit has non zero length the reflections from the internal walls will make a difference but then it is not a single slit experiment. --Gr8xoz (talk) 07:59, 7 October 2010 (UTC)

If it's not the reflection or absorption of the neighbouring wavelets by the walls I don't know what ultimately generates the diffraction pattern. I mean, you can apply Huygen's principle to light passing through a vacuum (or air). John Riemann Soong (talk) 08:25, 7 October 2010 (UTC)

If the wavelength of the light is equal to or less than the thickness of the wall, then the walls of the slit will cause some scattering. If the wavelength is long compared to the thickness of the wall, you can ignore the thickness. Looie496 (talk) 17:36, 7 October 2010 (UTC)

Einstein's view

After read his religious view i still don't get whether he believes in god or not. Second question, did Albert Einstein do not believe in the existence of black hole?174.20.65.111 (talk) 05:58, 7 October 2010 (UTC)

Regarding religion: he didn't believe in any god that takes a special interest in the affairs of humans. He did express a reverence for the workings of nature that could be called religious. I don't know what to say beyond that. You might find wikiquote:Albert Einstein helpful. Regarding black holes: I know he didn't believe in them at first, but I don't know whether he ever changed his mind. The understanding of general relativity was still very primitive by modern standards in 1955 when Einstein died—the event horizon, for example, wasn't really identified until 1958 (see Black hole#Golden age). So probably he never changed his mind, but he might have changed it if he'd lived a couple of decades longer. -- BenRG (talk) 07:03, 7 October 2010 (UTC)

Yes. Like many (but not all) scientists and other highly intelligent people that still choose to believe in a god, Einstein's belief system was probably far more complex and nuanced than that of your regular believer. It can thus be very hard to determine exactly what their actual beliefs are, because they are not easy to define in the usual simple yes/no categorisations, and additionally they often avoid sharing the full depth of their personal beliefs in public fora. --jjron (talk) 07:23, 7 October 2010 (UTC)

My understanding after I have read the article is that he mostly used god as a metaphor for the overall order in nature and the sum of all natural laws. He did clearly not believe in a god you can interact with. I do not think he believed in an afterlife. He believed in the historical existence of Jesus but not in him being god. He made some ambiguous statements.--Gr8xoz (talk) 07:42, 7 October 2010 (UTC)

I presume you've read Albert Einstein's religious views?

The answer to your first question depends on how you define the word "god". There is no universal agreement as to what "god" means; there are lots of different conceptions of god. But I'm guessing that you're thinking of the word "god" in such a way that the answer to your question is "no". Einstein didn't believe in any kind of a personal god, which eliminates the conceptions of god held by most Christians. Saying that Einstein believed in god would only be true if you define "god" as just meaning something like "the lawful harmony of the world," or "the sublimity and marvelous order which reveal themselves in nature". That's not really "god" like I presume you’re thinking of that word. He basically just had a great admiration of nature. Red Act (talk) 07:45, 7 October 2010 (UTC)

It's not just a "great admiration of nature," it's more like, "a supreme faith in the notion that nature must be orderly, perfect, and knowable." Which is a bit different. This is one of the reasons he hated quantum mechanics — it seemed un-orderly to him, it seemed necessarily "incomplete" because it claimed that nature wasn't knowable. (Cf. the famous "God doesn't play dice" quip — which really means, "nature doesn't operate in an un-orderly fashion.) It's a form of faith to be sure, but not one that lines up very well with standard conceptions of organized religion. There are echoes of Spinoza through it. --Mr.98 (talk) 11:22, 7 October 2010 (UTC)

There are a lot of fairly respectable sites on the internet which say that Einstein didn't believe in black holes.[24][25] Note that Einstein's belief or non-belief in a scientific theory later in his life is hardly a sign of anything. Oppenheimer quipped at one point that Einstein was a signpost along the way to modern physics, not the path of physics itself (or something along those lines — a signpost of where physics had been, not a lighthouse pointing the way forward, or something). Anyway, in Einstein's day, black holes were nothing more than a few clever mathematical manipulations of the field equations, pushing them to their limits. He didn't think there was a reality to them. Most physicists did not take the idea of black holes very seriously at the time. In the early days of such theory-derived ideas, they are usually treated as mathematical curiosities, but not necessarily as something that exists in nature. (See, e.g., tachyons for a good analog. Do they exist? The theory says that might be able to exist, under current knowledge. But does that mean they must or do exist?) --Mr.98 (talk) 11:31, 7 October 2010 (UTC)

I'm not familiar with the history, but that doesn't seem right to me. The existence of black holes is an obvious consequence of the basic principles of general relativity -- if you have enough mass in a region, then light can't escape from it. There is however a question about whether a black hole contains a singularity at its center -- a point at which the curvature of space becomes undefined. Straightforward application of the equations of GR do produce a singularity, but many physicists have doubted whether the equations are completely accurate in that regime. Looie496 (talk) 17:33, 7 October 2010 (UTC)

What you just said about the singularity is more or less how people felt about (what's now called) the event horizon in 1955. They thought it was a bug in the theory that would go away. It might have been an artifact of the Schwarzschild vacuum's unrealistic amount of symmetry. They didn't have the rotating or charged black hole solutions yet, or the theorems saying that the formation of a black hole is inevitable in certain conditions, or the principles of black hole thermodynamics that make black holes seem like physically reasonable objects. -- BenRG (talk) 19:29, 7 October 2010 (UTC)

It's worth noting as well that GR itself is basically unstudied and unhip until the 1950s. The hip things in the 1920s-1940s are particle physics and nuclear physics. It is only in the 1950s that gravity and GR become even standard parts of grad student physics curriculum in anything other than a cursory fashion. --Mr.98 (talk) 20:18, 7 October 2010 (UTC)

Why do Some people have heavier sleep than others?

I have noticed that in my family my mother has extremely light sleep (she wakes up to the slightest noises) while me and my father have very heavy sleep and do not wake up very easily. I was wondering why this difference exists. Is it genetic reasons? and if so why? is it based on a particular region of your brain and how it functions? why do some people need deeper sleeps? or could it be an environmental reason depending on whether you grew up in a noisy environment and had to adjust to sleeping through it?Morvarid rohani (talk) 06:48, 7 October 2010 (UTC)

In my opinion it's environmental. You get used to sleeping through noise, or you don't. But only up to a limit, I know some people who are hard to wake up even if you shake them, that's probably genetic. So like most questions of this type the answer is: Both! :) Ariel. (talk) 08:30, 7 October 2010 (UTC)

There'd obviously be components of both in there, possibly more genetic. For example as a kid I was a pretty heavy sleeper while one of my sisters was a light sleeper. Same environment, but then again also similar genetics. I spose you could proffer the argument that the elder child could be conditioned to quieter surroundings and thus be more prone to be a light sleeper, whilst a younger sibling would more likely be growing up in a far noisier environment and thus tend to be a heavier sleeper. --jjron (talk) 12:03, 7 October 2010 (UTC)

Complete speculation and original research, but I tend to notice mothers as lighter sleepers (but not all the time). Could this be down to the urge to protect offspring? Regards, --—Cyclonenim | Chat  17:35, 7 October 2010 (UTC)

This is OR, too, but my doctor told me that recent mothers, in particular, awaken easily, for this reason. Comet Tuttle (talk) 20:45, 7 October 2010 (UTC)

Where to focus to photograph a mirror reflection

So say I want to take a photograph of a reflection of myself in a plane mirror. For argument's sake lets assume I'm using manual focus on my camera. Should I set the focus to the surface of the mirror (i.e., the distance from me to the mirror) or to the apparent location of the virtual image (i.e., twice the distance from me to the mirror) in order to get myself in perfect focus? (And yeah, I know I can do a practical test on this, and will sometime, but I want to hear what people have to say first. :) ) --jjron (talk) 07:12, 7 October 2010 (UTC)

To take photograph of reflection you must focus on the reflection i.e twice the distance between you and mirror. Focus on mirror if you want to take photograph of mirror surface (scratches, dust etc on surface) - manya (talk) 07:20, 7 October 2010 (UTC)

You may find this experiment interesting. - manya (talk) 07:25, 7 October 2010 (UTC)

Cheers. That's the sort of thing I tried to find in a quick search myself, but had no luck. Will give this experiment a go myself sometime to try to verify this. --jjron (talk) 12:10, 7 October 2010 (UTC)

Chicken genome nuggets

I heard that the chicken genome on UCSC is going to get updated some time soon-ish. How can I find out how soon? Why can't they just release the information they have instead piecing it together for four years and releasing it in one go? --129.215.5.255 (talk) 09:54, 7 October 2010 (UTC)

The UCSC genome browser is a fantastic tool, but I'm not sure if they are directly involved in the chicken genome assembly... Usually the UCSC incorporates genome information after the genome assemblies have been completed by other groups. You could try the NCBI chicken genome page for more info on the chicken genome in particular. However, as a general rule, each assembly of a genome takes into account a significant amount of new genome data that sometimes results in re-mapping certain parts of the genome that were incorrectly assembled in the previous version. One consequence is that the numbering of the nucleotides can be dramatically different from one genome assembly to the next, which requires complete re-annotation (or at least conversion of the existing annotations to a new coordinate system). As you can imagine, this can be a huge computational task. In order to achieve some degree of stability, those involved in assembly and annotation of the genomes try to batch the new data into relatively comprehensive updates (which can sometimes take months or years). Plus, the end users of the data would go nuts if the gene coordinates were changing on a monthly, weekly, or daily basis every time a new fragment of the genome were decoded. --- Medical geneticist (talk) 12:38, 7 October 2010 (UTC)

diffraction of white light versus monochromatic light

Is there a difference in the Fraunhofer diffraction pattern through a slit made if the average wavelengths of the light are the same? What if I have a bimodal distribution of red and violet light, say? John Riemann Soong (talk) 09:59, 7 October 2010 (UTC)

Yes, each wavelength is diffracted individualy, the average wavelengths has no significance. --Gr8xoz (talk) 13:50, 7 October 2010 (UTC)

So why then does white light result in such an orderly pattern, and why do people generally quote the average wavelength of light for microscopy? John Riemann Soong (talk) 15:53, 7 October 2010 (UTC)

Pressure cooker - rubber ring

What is the function of ring made up of rubber in pressure cooker apart from sealing the cooker. ...thanx--Myownid420 (talk) 10:30, 7 October 2010 (UTC)

It seals the gap between the bowl and the lid so that pressure can build up in the bowl and the temperature of the liquid contents can rise above the normal boiling temperature of water. Nothing else. Dolphin (t) 10:57, 7 October 2010 (UTC)

Can expressing GFP interfere with any cellular processes?

I'm starting a project whereby I'll try to knockout a gene by homologous recombination (induced by zinc finger nucleases) of a marker such as GFP into said gene. I would prefer to just disrupt the gene by inducing NHEJ since the efficiency should be high enough that selection using a marker isn't really necessary. I don't like the marker method, because I don't trust that expressing GFP doesn't have some (negligible?) effect on the cell. Has anyone investigated (e.g. by microarray or 2D-PAGE) the effects of GFP expression on cell activity? Does anyone share my preference to simply knock out the gene without adding anything or am I just a bionoob? ----Seans Potato Business 10:50, 7 October 2010 (UTC)

Green fluorescent protein has a pretty long track record of being innocuous when expressed at reasonable levels in cells or organisms. There are numerous transgenic animals that express GFP without any obvious toxicity, and thousands upon thousands of in vitro experiments where GFP alone is used as a control to study the effect of a GFP fusion protein. It is certainly true that when GFP was first being introduced into cells there was quite a bit of concern about toxicity or disruption of cellular processes. I think that one of the "red" fluorescent proteins was notorious for causing toxicity, but the weight of evidence seems to indicate that GFP is benign. Of course, massive overexpression of any protein can disrupt cellular processes, but I'd say that your application is pretty safe if you have the transgene being expressed by the endogenous transcriptional machinery or a simple basal promoter. --- Medical geneticist (talk) —Preceding undated comment added 13:07, 7 October 2010 (UTC).

Hmmm, I came up with PMID 15655375 — is this useful? This is one of those cases where I think you actually need to use a MeSH topic rather than a keyword to search PubMed for Green fluorescent protein, to get papers about GFP rather than those merely mentioning it. Wnt (talk) 13:10, 7 October 2010 (UTC)

Coin question

Four coins are thrown from a bridge. Coin a is thrown vertically upward, coin b is thrown horizontally, coin c is thrown up at a certain angle with the horizontal, and coin d is dropped from rest. Assume that the initial speeds of coins a,b,and c are equal. Which among the coins will reach the water first? Which will be the last to hit the water? Which among the four coins will hit the water the same time? —Preceding unsigned comment added by 121.54.32.155 (talk) 11:11, 7 October 2010 (UTC)

Added new header. --Chemicalinterest (talk) 11:21, 7 October 2010 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. I can give you hints. Which will obviously be the first to hit the water? --Chemicalinterest (talk) 11:21, 7 October 2010 (UTC)

This depends enterily on when the different coins are thrown/droped but if they are droped in the given order with enugh time in between then coin a will hit the water first. This is ofcurce only valid if the bridge is over a free water surface. --Gr8xoz (talk) 13:43, 7 October 2010 (UTC)

If it's over a temporarily dry Wadi, it depends on whether you stand on the upstream or downstream side, on the angle with the horizon for coin c, and the initial speed for coins b and c. Whichever coin lands farthest upstream will get wet first. ;-) --Stephan Schulz (talk) 15:19, 7 October 2010 (UTC)

I can guess the answer the teacher is looking for here, but I don't believe it. Coins have tricky aerodynamics. APL (talk) 15:28, 7 October 2010 (UTC)

well, here's a homework hint: making all the standard physics assumptions (i.e., ignoring aerodynamic effects, assuming a flat featureless plain below - though why one would need a bridge on a flat featureless plain is beyond me), you only need to deal with initial velocity in the direction of the pull of gravity. think about it. --Ludwigs2 16:52, 7 October 2010 (UTC)

The teacher is obviously assuming a Spherical cow. --Zerozal (talk) 17:58, 7 October 2010 (UTC)

splash!splash! That is coins b and d hitting the water simultaneously but the sound of coin b took longer to reach you. Then splash! That was coin c hitting. But wait, what happened to coin a ? Hmmm, can't hear anything. Wait a bit. OUCH! That was coin a hitting your head. Ejecting coins in four different directions at once is difficult and perilous. Cuddlyable3 (talk) 20:46, 7 October 2010 (UTC)

Metal detectors outside MRI rooms

On Monday I watched the show House, MD on TV and a lady's leg started frying because of some metal pins in it she didn't tell the doctors about. It seemed like such a thing could easily be prevented by simply going through a metal detector on the way to the MRI room. Do real hospitals do this? 20.137.18.50 (talk) 12:16, 7 October 2010 (UTC)

Our article MRI#Safety discusses some of the dangers and safety measures taken. These types of things are rare and can often be avoided by simple precautions and questions asked of the patient. The TV show House (as you are undoubtedly aware) is fiction, and as such the producers take certain liberties with medical reality and quite often stretch the truth to make the show a bit more "interesting" for the TV viewer. --- Medical geneticist (talk) 12:21, 7 October 2010 (UTC)

Thanks. I agree on the fiction of House and the rarity of MRI incidents. I read the referenced article, specifically "There are many steps that the MRI patient and referring physician can take to help reduce the remaining risks, including providing a full, accurate and thorough medical history to the MRI provider." But at MRI#Projectile_or_missile_effect it does say "Missile-effect accidents, where ferromagnetic objects are attracted to the center of the magnet, have resulted in injury and death." and there are references to the actual cases. Those undoubtedly could have been caught by a metal detector. And not checking something so easily checkable since it can often be avoided by simple precautions and questions asked of the patient just seems strange. For instance, I have a blood donor card that is clearly not counterfeit (throw in the odds of who would really go to the effort of counterfeiting a blood donor card) but they still do the test to check what type my blood is. 20.137.18.50 (talk) 13:12, 7 October 2010 (UTC)

It's of note that a security metal detector wand (like used in airports) costs only $100-$200. A walk-through metal detector (again like in airports) costs from $3000. I would think that the former would actually be a good investment — cheap, easy to use, and would help with metal that people might not know about (e.g. an embedded BB from childhood that had long been forgotten, or metal shavings from an accident, or something). The latter probably tips the cost/benefit towards cost in all but very large hospitals or facilities. On the other hand, the possibility of false positives might be too high, or, worse, it might open the doctor/hospital up to liability if they have a false negative. Of course, if the rate of accident and danger of accident are both very low, then it wouldn't warrant it. But it strikes me that there would be some patients who either couldn't be relied on to give oral information about such a thing (e.g. the very elderly, or the mentally ill, or children, or the comatose/injured). I would be surprised if they didn't have some kind of technical screening process for them. --Mr.98 (talk) 13:13, 7 October 2010 (UTC)

I have walked through many metal detectors with metal on myself such as a belt buckle, keys, and a watch. Having metal detectors that are unable to detect small items of metal would do nothing more than cost a lot of money and create a false sense of security. -- kainaw™ 13:17, 7 October 2010 (UTC)

But you've walked through those ones because the tolerance was set low. You can adjust the tolerance on such machines. If you go through them on a regular basis (as one would working in Washington, DC, where every government building of any size has one), you get used to what they are set to — some are set to go off with pocket change, some you can wear a belt through. Presumably you'd have to figure out how to set their tolerance level to the tolerance level required for the MRI purpose. --Mr.98 (talk) 13:18, 7 October 2010 (UTC)

(edit conflich with Kainaw, Mr. 98) How accurate are metal detectors? They're generally made for detecting weapon-size metal objects, rather than metal-shaving size objects. Weapon-size objects are the types of things that patients and doctors are more likely to know about anyway (medical implants mostly, I suppose), whereas it's metal shavings in the eye, or something like that, that's the real danger in most cases. Buddy431 (talk) 13:20, 7 October 2010 (UTC)

Just found out... Metal detectors are very sensitive to MRI machines. So, they have to be kept a good distance from them. The metal detectors that are "MRI safe" are very expensive and still have issues with reliability when the MRI is in use. There are ones designed for use in MRI areas, like this. So, if they manufacture them, some people must be using them. -- kainaw™ 13:22, 7 October 2010 (UTC)

Looks like that one is still intended for keys and change, as at the bottom of the page it says "Metal detectors are not intended to detect metal items or implants inside the body. They will not pinpoint the location or even determine the presence of metal inside the body. A bobby pin in your patient's hair, a key ring in someone's pocket or metal on an item being brought in for use can be discovered with a high-sensitivity detector properly used." 20.137.18.50 (talk) 13:31, 7 October 2010 (UTC)

(ec) In general, what you will find is the vast majority of MRI-associated 'projectile' accidents aren't due to concealed or implanted objects, but simple carelessness. Nurses or orderlies don't take care with metal wheelchairs, gurneys, IV stands, or gas cylinders which may contain ferromagnetic parts. Technicians or custodial staff bring a toolbox or floor polisher or other ferromagnetic object into the imaging suite, and stray too close to the magnet. In other words, people usually know when they are bringing metal objects into the room, but fail to take appropriate precautions. As much as possible, patients will be gowned during the exam, and unable to conceal keys or coins in their pockets.

In the case of patients with implanted metal objects, this will usually be revealed by a proper medical history. Where a history is unavailable, where the patient is unsure, or where a patient may have been inadvertently exposed to metal fragments or shavings (a history of metalworking or machining work, for instance) it is standard procedure in most hospitals – particularly for studies of the head – to obtain a radiograph (x-ray) of the area. This is far more sensitive than the use of an external metal detector. TenOfAllTrades(talk) 13:38, 7 October 2010 (UTC)

Do amalgam tooth fillings cause problems or dangers with MRI machines? 92.28.245.77 (talk) 13:27, 7 October 2010 (UTC)

Fillings (and other orthodontics) don't generally cause safety issues, but they will tend to interfere with imaging in the area immediately around the metal. TenOfAllTrades(talk) 13:47, 7 October 2010 (UTC)

It is my privilege to introduce Reference Desk visitors to this article from the amazing site politedissent.com, in which a medical doctor reviews the medical details of each and every episode of House M.D. On this particular point, the author writes: "Not to beat a dead horse, but a halfway decent physical exam would have revealed the surgical scars on her shin and the likelihood of an orthopedic repair. A quick x-ray would have confirmed metal pins. At our facility, if the radiologists even suspect some metal in the patient’s history at all, x-rays are ordered." TenOfAllTrades wins. Comet Tuttle (talk) 20:20, 7 October 2010 (UTC)

Seeing through frosted glass or net curtains with a telescope or zoom lens

By focusing on the scene or object of interest beyond, rather than on the frosted glass or net curtains, is it possible to see through them? I expect it is easier to do this the greater the distance between the object/scene and the net cutains, and the nearer the net curtains are to the observer. 92.28.245.77 (talk) 13:25, 7 October 2010 (UTC)

To an extent, but you'll still be limited by the opacity of the object - i.e., focussing off in the distance doesn't make something you can barely see through suddenly transparent. An example of where you can do this is something like a wire fence - photographers at events like Formula 1 sometimes have to shoot through a fence, but the fence isn't really visible in the photo. A trick they use which helps even more is to colour in the mesh black rather than leaving it silver as that makes it even less visible in the photo. --jjron (talk) 15:07, 7 October 2010 (UTC)

Yes to net curtains; no to frosted glass. For the net curtains, the mesh will not be in focus at the plane of the film in the camera. Light coming from (reflected by) the curtains will be 'spread out' over the film plane; if the curtains are brightly illuminated then this may reduce the contrast of the resulting image. On the other hand, the light from the subject – at least, the portion which will pass straight through the gaps in the curtain – can be focused sharply to form a proper image. Note that the apparent brightness of the subject is going to get reduced in proportion to the fractional coverage of the curtains — that's how much light is blocked by the curtains and therefore unavailable for forming an image.

Frosted glass, on the other hand, diffuses and scatters light. If the light no longer follows a straight path from the subject to the camera, then the lens will be unable to focus it into an image. TenOfAllTrades(talk) 15:50, 7 October 2010 (UTC)

Mushroom identification

Anyone know what this is? I origanlly thought it to be the infamous Death cap (Amanita phalloides) but on CommonsWiki someone said that it is probably something else, maybe Amanita gemmata or some other Amanita species. Anyone have any ideas? --The High Fin Sperm Whale 16:59, 7 October 2010 (UTC)

It's hard to tell from that picture (can't see the stem or gills) and I'm not sure where you're based, but it looks a bit like Amanita citrina to me. Brammers (talk/c) 18:34, 7 October 2010 (UTC)

As you can see from the geocodes, it is in Langley, British Columbia. --The High Fin Sperm Whale 18:47, 7 October 2010 (UTC)

Ah, sorry about that; I hadn't thought to look there. Maybe it's worth changing the file description while its species is still not certain? Brammers (talk/c) 18:49, 7 October 2010 (UTC)

I think I'll wait until I can tell for sure. Feel free to ask any questions about it. --The High Fin Sperm Whale 20:03, 7 October 2010 (UTC)

Boiling milk in a microwave oven

I was making a hot drink today, and as usual I poured the milk into a glass jug and popped it into the microwave. Just "normal" 2% pasteurised milk. When it was bubbling nicely, I took it out and the milk had separated like happens when it goes off. It smelled bad too. The milk in the bottle smelled fine (and tasted fine) and was not in the slightest bit lumpy, but just to be sure I threw it out. I've never seen milk go off instantly like this. Any ideas as to what happened? --TrogWoolley (talk) 18:28, 7 October 2010 (UTC)

Milk burns very easily when heated. Part of it probably burned, and the bubbles spread it around. --The High Fin Sperm Whale 18:48, 7 October 2010 (UTC)

Red mud into iron?

Can Red mud be refined into iron? (I don't mean physically, I mean practically/economically.) Ariel. (talk) 22:05, 7 October 2010 (UTC)

No, because if it could, it would be being done. Companies are not usually in the business of throwing free money away, so if the waste could be refined in such a way as to make more money for the company, they would be doing that rather than leaving it in giant open sewers next to the Danube. --Jayron32 22:14, 7 October 2010 (UTC)

I've only got old data immediately to hand, but let's say that the production of iron is 20–50 times greater than the production of alumina (that's probably order-of-magntitude correct). At those sorts of scales, there's no economic incentive to create a new process to deal with this strange "artificial" iron ore rather than using the existing well-known processes on standard iron ore. Physchim62 (talk) 22:25, 7 October 2010 (UTC)

Is "dark energy" really the Universe's brane whipping around?

I just read a Scientific American article which claims that "dark energy" is really the Universe's brane whipping around, and that this will eventually fold the brane in on itself, converting time into a spatial dimension, which would in turn require everything to move faster than light and thus freeze time. Is it true that the supposed "dark energy" is really a signal that the end of time is approaching? --70.245.189.11 (talk) 22:25, 7 October 2010 (UTC)

Well, if there is an "end of time", it's approaching at a speed of about 24 hours per day. However, there are no solid theories about the structure and implications of dark energy yet. According to all we know, the current structure of the universe will remain essentially as it is now for billions and billions of years. Don't expect the end (if any) soon in human terms. --Stephan Schulz (talk) 22:33, 7 October 2010 (UTC)

The article said that, if our brane started whipping around, galaxies would appear to speed up in a way that's consistent with observations, and that this would culminate in everything freezing in place because they'd have to move faster than light. --70.245.189.11 (talk) 22:38, 7 October 2010 (UTC)