:The idea behind the metric system was, as Looie points out, twofold. First was to develop a universal standard, so that the US and the UK and France and Japan all knew that if you said something was a given length or weight, it was. This is in contrast to systems that were sometimes quite localized, and a "pound" or a "foot" could mean different things in different places. Second was to develop a system that was decimalized, because it is easier to do many calculations with decimalized systems than non-decimalized. 12 inches to a foot, three feet to a yard, dividing inches into 1/16ths, 5280 feet to a mile... this is a pain, quite arbitrary, and makes it hard to covert between units (how many 1/16ths of an inch are there in a mile? Not the easiest calculation to do in your head). Decimalization lets you just change prefixes and do things in orders of 10. That's pretty easy to do. As for what feels "intuitive" to you—it's entirely what you grow accustomed to using. I find miles intuitive but that's just because I've grown accustomed to thinking in terms of them. It's entirely arbitrary. Which is not to say that in ''all'' fields decimalization is easier; in time, for example, there is a strong argument that decimalization doesn't actually save much effort on calculations, and in fact impedes certain types of calculations. --[[User:Mr.98|Mr.98]] ([[User talk:Mr.98|talk]]) 20:20, 17 July 2010 (UTC)
:The idea behind the metric system was, as Looie points out, twofold. First was to develop a universal standard, so that the US and the UK and France and Japan all knew that if you said something was a given length or weight, it was. This is in contrast to systems that were sometimes quite localized, and a "pound" or a "foot" could mean different things in different places. Second was to develop a system that was decimalized, because it is easier to do many calculations with decimalized systems than non-decimalized. 12 inches to a foot, three feet to a yard, dividing inches into 1/16ths, 5280 feet to a mile... this is a pain, quite arbitrary, and makes it hard to covert between units (how many 1/16ths of an inch are there in a mile? Not the easiest calculation to do in your head). Decimalization lets you just change prefixes and do things in orders of 10. That's pretty easy to do. As for what feels "intuitive" to you—it's entirely what you grow accustomed to using. I find miles intuitive but that's just because I've grown accustomed to thinking in terms of them. It's entirely arbitrary. Which is not to say that in ''all'' fields decimalization is easier; in time, for example, there is a strong argument that decimalization doesn't actually save much effort on calculations, and in fact impedes certain types of calculations. --[[User:Mr.98|Mr.98]] ([[User talk:Mr.98|talk]]) 20:20, 17 July 2010 (UTC)
:Nobody seems to have mentioned that it incorporates (not by chance) conversion factors of 1. eg 1 cubic meter of water weighs 1 metric tonne, or 1 cubic centimetre of water weights 1 gram (ie based on water of density 1 unit). ''also'' Move a force of 1 newton through 1 meter and you've done 1 joule of work. Compare with the various conversion factors for 1 footpound.[[Special:Contributions/87.102.32.76|87.102.32.76]] ([[User talk:87.102.32.76|talk]]) 20:36, 17 July 2010 (UTC)
== How portions of the brain are identified ==
== How portions of the brain are identified ==
Revision as of 20:36, 17 July 2010
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
Unless this is a trick question, i think the answer would obviously be yes. That's why you don't cave in or blow apart, up to a point. It's when you can no longer equalize the pressure with your environment that one of those two things might happen. Vespine (talk) 05:10, 13 July 2010 (UTC)[reply]
This subject is complicated, so if you want more details please ask. The pressure changes somewhat. In a liquid and a solid pressure has little effect, but in a gas pressure presses the atoms closer together. Note: this is only an approximation. So if a person goes into an area of lower pressure nothing much happens to the liquid that makes up the body. Officially the pressure is lower, but practically speaking there is no change. Except for the air in the lungs - but that air equalizes with the air outside. There is one caveat, at lower pressure liquids boil easier (vapor pressure). So in a low pressure environment the liquid might try to boil. When a liquid boils the pressure goes up, which will try to stretch the blood vessels (for example). But the blood vessels refuse to stretch (somewhat), which will result in a higher pressure inside the blood vessels than in the air outside. Which is why I said somewhat - the pressure is lower, except if it's low enough to cause water to boil, in which case the body will prevent it, and will end up with a higher pressure than outside. Another change with pressure is gas solubility. Gases dissolve in water (like seltzer), the higher the pressure, the more they dissolve. Going from regular pressure to vacuum, there is little change. But at high pressure a lot of gas might be dissolved in the blood. If a person goes to an area of lower pressure, that gas will come out, and it's too much pressure for the blood vessels to prevent. Ariel. (talk) 06:09, 13 July 2010 (UTC)[reply]
iPhone 4 antenna
So it's largely confirmed that bridging the lower left gap on the new iPhone reduces the cellular signal strength by around 20db, but as an electronics engineering student 20db seems to be a lot to me, especially after spending a lot of work building a 12dbi UHF antenna. Will changing the geometry of the antenna really cause such a substantial drop in antenna gain, or is there another reason behind it (interaction with the human body/ with WiFi)? --antilivedT | C | G03:25, 13 July 2010 (UTC)[reply]
Yes I already know that the antenna gets detuned due to the hand bridging the gap, but I'm wondering will a detuned antenna really drop the signal by 20dB (that's a 100-fold reduction in RF power), or is there some other factor too? --antilivedT | C | G04:20, 13 July 2010 (UTC)[reply]
The iPhone4's antenna wraps around the case with a small gap. When you bridge the gap, you're effectively shorting out the antenna completely. If you have one, then at this point, your best bet is probably to buy a soft case for the phone. SteveBaker (talk) 14:43, 14 July 2010 (UTC)[reply]
Electrophoresis
Hi,
A while ago an idea occurred to me about separating ions in an aqueous solution, but I wasn't sure if it would work or what would happen and haven't found much information since then either so I thought I'd ask here. Basically what I was thinking was, if you had a ionic solution - say salt water - and if you applied an electric field, then the +ve ions would move in the direction of the field and the -ve ions would move opposite to the field, until that movement created an equal and opposite field. So in the brine, if put two parallel metal plates on either side of the solution (insulated from it of course) and applied a voltage across them, then the Na and Cl ions would move slightly towards -ve and +ve plates respectively. Now if you put a solid partition down the middle of the set up and removed the field, you'd have a one solution with a slight excess of sodium ions and a another with a slight excess of chlorine ions.
My questions are: would it work at all? And if so, what would the properties of the created solutions be?
After looking up on google and wikipedia I eventually found "electrophoresis" which seems to be what I'm thinking about, and seems to indicate that it would work; but beyond that, I can't find any more useful info - mostly just stuff about seperating DNA and whatnot, leaving my second question unanswered. The kind of stuff I'm wondering is, for example, what would happen if you tried to evaporate the water? Would the ions evaporate too? Or what if you dipped a positively charged plate into the solution with excess chlorine? Would the excess ionic chlorine then lose electrons and turn into chlorine gas??
Are you certain they would actually move? Because water is also ionic, and the H and OH groups should also separate, but obviously they don't. I think you need energy input to separate the ions, an electric field is not enough (unless you were somehow taking energy from it, in which case it would do the same as electrolysis). Ariel. (talk) 06:36, 13 July 2010 (UTC)[reply]
I wouldn't bet money that they would move, but I can't see why they wouldn't - the energy input would come from the transient (displacement) current that would flow when you introduce the field, in the same way as energy is stored in a capacitor even though, once you've charged it, no current flows and no energy is transferred. As for the water, I suppose it would also move, but I'm assuming that it would only rotate, with most of the movement happening with the ions (since I guess it'd take less energy to move the ions than break the covalent bonds of the water, in same as that when you perform the electrolysis of brine it's the salt rather than the water that comes apart). 202.37.61.14 (talk) 07:29, 13 July 2010 (UTC)[reply]
Yeah, I know, but I wasn't talking about electrolysis; in fact the whole notion entered my head when I wondered what would happen if you could avoid the oxidation and reduction that happens in electrolysis. 202.37.61.14 (talk) 10:26, 13 July 2010 (UTC)[reply]
202.37 is correct as far as what we're describing here is, effectively, a capacitor, with an (insulated) bag of saltwater acting as the dielectric between the plates. Now, what happens when you apply an electric field across our bag of saltwater? The saltwater solution will become polarized, arranging itself (as the original question notes) opposite the appplied field. How does that come about? There are a few possibilities. 1) The sodium and chloride ions can migrate to generate a charge gradient across the solution. 2) The water molecules can ionize, generate a large pool of free hydrogen/hydronium and hydroxide ions which can migrate. (The very small population of these ions naturally present near neutral pH is also able to migrate.) 3) The water molecules orient themselves so that their existing dipoles align. 4) The molecules in solution become individually polarized — induced dipoles are generated by distortions to each molecule's (or atom's) electron cloud.
In practice, (4) is a very fast process, and (3) is quite quick too. (1) requires movement of ions over distances which are large (for molecules) and would be rather slow. I suspect it also has a heavy entropy penalty, and so is thermodynamically less favorable. (2) requires ionization of water and is probably quite energetically costly — so also unlikely to make a significant contribution unless the 'cheaper' processes have been exhausted. While I haven't done the math, my gut instinct here is that induced dipole formation and dipole orientation will be responsible for the vast majority of the polarization of the sample, and you won't see significant ion migration and separation until you get very close to the breakdown voltage of the dielectric. TenOfAllTrades(talk) 13:45, 13 July 2010 (UTC)[reply]
A very tiny amount of charge separation will prolly occur. This is because separating as much as 0.000000000000001 mol of Na+ and Cl- (probably smaller) over that distance will result in a HUMONGOUS field that will cancel out the previous field.
Now, that sort of charge separation is so unstable, so with lots of mutual Na+ repulsion and mutual Cl- repulsion, Na+ stops becoming an inert counterion and becomes Lewis acidic, generating a proton gradient, which will travel over to the chloride-dense side. Meanwhile at that density, the chloride ions will actually start to become basic. Part of this is due to Coulombic forces, part of this is due to the entropy considerations (so much charge separation ==> lots of water ordering). You'll end up making HCl and NaOH, or possibly NaOH, Cl2 and H2.
I am creating a page on my school from where I graduated 3 years ago. I have all the required data needed but do not have a website of reference since the school itself does not have one. Can I still continue with my article?—Preceding unsigned comment added by Nepalsk (talk • contribs)
The best place for this question would be at the Help Desk. They answer questions about how to edit Wikipedia there. This is the Reference Desk where we answer questions about things outside of Wikipedia. Dismas|(talk)05:48, 13 July 2010 (UTC)[reply]
Have a read of Creating a new page. There are thousands of schools in the world, do they all really need a encyclopedia article about them? If the school in question doesn't have a website, and you are struggling to find any references, it could be that the school is simply not notable enough to warrant its own article. Why should the school have a page? Don't take it personally but if the only answer you can think of is because you graduated from it, I'm not sure that's a valid enough reason. Vespine (talk) 05:52, 13 July 2010 (UTC)[reply]
If you were in the UK, you'd be able to find Ofsted reports on the school online, as well as potential menions in local history books if it's been around a while. Is there an equivalent of Ofsted reports available in the country in question? That would ensure at least some sources. 86.164.57.20 (talk) 14:00, 13 July 2010 (UTC)[reply]
For what it's worth, I thought the answer would be "No, you may not write about your high school" too! But I thought I'd find the official guideline and quote what it said - and it's just as well I did! Amazingly (to me), all high schools are now automatically considered notable. That certainly wasn't always the case because not long ago I had to fight off an RfD for my Alma Mater Chatham House Grammar School - in my case it was easy because Chatham House is the oldest government-run school in the UK and Sir Edward Heath (one time Prime Minister of the UK) was a fellow "Old Ruymian". I figured that if a school like that has to fight to be considered notable, most other schools would have no chance! But it looks like the policy has changed...which (IMHO) is a good thing. SteveBaker (talk) 23:22, 14 July 2010 (UTC)[reply]
It doesn't seem to be. The picture I linked shows that it starts from cholesterol. The article on HGH does mention that the production of HGH is stimulated by androgens (like testosterone), but not the reverse. Ariel. (talk) 06:31, 13 July 2010 (UTC)[reply]
No, HGH is not a precursor to testosterone. HGH is a polypeptide (well, actually a group of related polypeptides). Testosterone is a steroid, derived from cholesterol. Axl¤[Talk]10:22, 13 July 2010 (UTC)[reply]
Can you 'boil' heat water by compressing it?
A gas heats up when compressed. I assume the same happens with a liquid. Now I know water is hardly compressible, so a huge lever would be needed, so to say, but it seems to me that that should be possible. But how far can you heat it up? What happens when it gets to the boiling point? It can't boil in the normal sense because it can't evaporate. This article says it forms a solid at 100 C (= 212 F). But is this practically feasible, with relatively everyday materials? What sorts of pressures would be involved? Several articles I found mention 'diamond anvil cell techniques', but how far could this be taken with a normal strong container, say a diving cylinder? DirkvdM (talk) 08:26, 13 July 2010 (UTC)[reply]
Have you come across a kitchen appliance called a pressure cooker? It cooks food in water in a heated sealed "cooker", taking advantage of the fact that the pressure of the steam raises the boiling point of the water. HiLo48 (talk) 09:00, 13 July 2010 (UTC)[reply]
On a side note, I can remember going to a science museum when I was a child, where they had a demonstration of the changing boiling point of liquids with pressure, in which a glass of water was sealed inside a chamber and an hydraulic system was rigged up so that when you pulled a knob the pressure in the chamber dropped dramatically, causing the water boil; so the opposite is certainly true - you can boil water by decompressing it, so to speak. 202.37.61.14 (talk) 10:14, 13 July 2010 (UTC)[reply]
(After edit conflict with Dr Dima below)
Yeah, I thoght about those two, but they're fundamentally different.
In a pressure cooker the pressure is the result of the heat. What I want is the reverse, produce heat as a result of pressure.
The goal is not to boil (evaporate) the water, but to heat it up. My mistake, I shouldn't have used the word 'boil'. Which is why I changed it into 'heat'.
But what I really want to know is if this can be done 'at home', or at least with simple materials, outside a laboratory environment and certainly not using diamonds. DirkvdM (talk) 10:49, 13 July 2010 (UTC)[reply]
Thermodynamics is not all intuitive. This is a great example. You can bring liquids to "boil" (I'll explain the quotes in a minute) both by compression and by expansion. -- 1 -- . Let us first consider expansion. Expansion is easy: drop the pressure below the vapor pressure for the given temperature of the liquid, and the liquid will start to boil. This is what 202.37.61.14 just described. If you keep pressure and temperature constant, the liquid will all boil out. If you do not keep temperature constant (do not provide heat source) but keep the pressure constant, the liquid will cool as it boils, and eventually stop boiling. This will happen when the vapor pressure -- as a function of temperature -- drops enough to match the value of the pressure that you maintain. If the pressure is maintained below the solid-liquid-gas triple-point pressure, the liquid will turn into mixture of solid (ice) and gas (vapor). -- 2 -- . Let us now consider compression. Compression is more tricky. As the OP said, liquid is heated when compressed. When the heat can escape, the compressed liquid will eventually turn into solid. However, when the heat produced has nowhere to escape, you end up raising both the temperature of the liquid (that is, the vapor pressure) and the boiling point (that is, the vapor pressure needed for the vapor bubbles to form). This competition is decided by a number of factors. The most important one is how you compress. If you compress gently (isentropically), the heating is weaker than when you compress violently (by a shock wave). I do not know if you can produce a liquid-gas mixture by sending a shock wave through water (no rarefaction, just shock); but you can definitely bring the water above the liquid-gas critical point. Above the critical point you cannot tell the liquid from the gas, so "boiling" has no meaning. If you allow the liquid to isentropically expand after the shock and to return to the original pressure, its temperature will end up higher than the initial one, and it may well boil. Finally, an extremely strong shock will turn liquid into plasma, which is essentially an extremely hot gas (so hot that some or all electrons leave the atoms and become free). So yes, you can turn the liquid into gas by either expanding it or compressing it; but you need to know how to compress or how to expand. --Dr Dima (talk) 10:29, 13 July 2010 (UTC)[reply]
Ah yes, I should have also mentioned that the heat is not allowed to escape (although that is somewhat inherent to the question), so a diving cylinder is inside a thermos flask, so to say.
And again, apologies about the use of the word 'boil', because that is not what I'm after. (Note, though, that I also put it between quotes, for just that reason). I want a rise in temperature, but by a considerable amount, not just a few degrees.
What I was thinking about is a gradual build-up of the pressure. But as I understand your last bit (which I don't fully), that is really about a shock wave. I was thinking more about something like cranking up the pressure by hand, with a lever.
Also, I was assuming there is no air in the container, just water. However, a small amount of air would be unavoidable in practise, and since that is (relatively) highly compressible, it would affect the process considerably, I suppose. But wouldn't it at some point be 'absorbed' by the water? So here's an added question. How much would all this be affected by any air in the container? DirkvdM (talk) 10:49, 13 July 2010 (UTC)[reply]
For not too large pressures, you can calculate this using the heat capacity and the coefficient of thermal expansion as follows. Since in this process no heat is exchanged with the environment, the entropy stays constant (assuming you compress it slowly). The differential of the entropy in terms of dT and dP can always be formally expressed as:
If we put dS = 0 and solve for the ratio dT/dP, you get the partial derivative (dT/dP)_S which tells you by how much the temperature will rise per unit pressure increase. However, using the above expression, you will get an expression involving the entropy. The coefficient of dT can be expressed in terms of the heat capacity a constant pressure:
To simplify the other coefficient, consider the fundamental thermodynamic relation
You can read this as T being the partial derivative of E w.r.t. S at constant V and minus P being the partial derivative of E w.r.t. V at constant S. The second derivative of E w.r.t. S and V can be evaluated by differentiating w.r.t. S at constant V first and then by differentiating w.r.t. V at constant S, or the other way around. The equality of the two ways of evaluating the second derivative yields that the derivative of T w.r.t. V at constant S is the same as the minus the derivative of P w.r.t. S at constant V.
Now, we want an identity involving the derivative of S w.r.t P at constant T. We can find that by partially integrating both terms in the fundamtal thermodynamic relation
So, we have
where G = E - T S + P V is the Gibbs free energy.
And then the symmetry of the second derivatives of G yields that
We can thus express this in terms of the thermal expansion coefficient
Putting everything together, you find that
where lowercase c_P is the specific heat capacity per unit mass and rho is the density.
At 25 °C and 1 bar, you find that this is approximately
1.48 *10^(-3) K/bar. So, you can see that you need to raise the pressure to thousands of bars to get just a few degrees of temperature increase. You can't then use the above linear formual anymore, of course, as the density and expansion coefficients will change. But it is still a good order of magnitude estimate. Count Iblis (talk) 16:03, 13 July 2010 (UTC)[reply]
Ah, thanks. I don't follow most of your first post (largely because I don't know what the symbols stand for), but the linear equation at 25 C is within my grasp. :) To increase the temperature just one C (or K), to 26 C, would require about 700 bar. That's 70 million Pa. Which is 70 million kg/m*s2. For 1 l = 1 kg of water that would mean .... excuse my continued ignorance, but how do I translate this into energy? And does that become more or less as the pressure and temperature increase? The density barely changes, and I assume there is hardly any thermal expansion and I further assume the two are inversely related. Or something. That's about as far as I get. Help! DirkvdM (talk) 17:23, 13 July 2010 (UTC)[reply]
You can use the fundamental thermodynamic relation
dE = T dS - P dV
and use that dS = 0. Put differently, because this is an adiabatic process, the work done on the system is the change in internal energy. It is convenient to express dV in terms of dP and dS:
If you substitute this in the fundamental thermodynamic relation and then put dS = 0, you find that the energy change is:
where is the isentropic compressibility. Now this can be expressed in terms of the isothermal compressibility and the heat capacity ratio, as derived in the article relations between heat capacities:
You can easily find the isothermal compressibility in tables. As explained in the same article, the specific heat capacity at constant volume can be expressed as:
So, we have:
All the quantities in this equation can be easily found. If we approximate things by assuming that stays constant as the pressure is increased (this should not be too bad an approximation), then integrating the equation for dE_{adiabatic} gives for the energy increase per unit mass:
So, it is proportional to the change in the square of the pressure. But you can compute things precisely by doing a numerical integration using tabulated values for the thermal expansion coeffcient, the isothermal compressibility and the density, if you also consider the equation for the temperature change derived above.
With only my half forgotten secondary school physics and math, I'm hanging on by my fingernails here. :) In the first equation, the change in energy, which is the energy one has to put in, is related to T, P and V, being temperature, pressure and volume, and S, which I now understand stands for mass, which indeed does not change, so dS=0. So in the second equation the first part after the equal-sign is 0, so it says the acutal change in volume is the change in volume per change in pressure times the actual change in pressure. That makes sense to me. But after that, I don't follow.
So let me skip to the final formula. Rho is density, which is mass per volume. For water, that is 1 kg/m3. is the isentropic compressibility. The compressibility article mentions this for water at 25 C (although I don't know if that's isentropic - I barely even know what that means): 4,6 * 10-10 m2/N = 4,6 * 10-10 m*s2/kg. For 1 C temperature change we found above that that requires a pressure change of 7 * 108 Pa = 7 * 108 kg/(m*s2). Fill all that in in the formula and we get
Hold on, I should have ended up with kg*m2/s2. My head is spinning slightly. I can't even read my own equations anymore. :) Where did I go wrong? DirkvdM (talk) 10:49, 14 July 2010 (UTC)[reply]
I find 1130 J/kg. The pressure is 700 bar = 7*10^7 Pa and the density is approximately 10^3 kg/m^3 (more precisely 997 kg/m^3). The cpompressibility is the isothermal compressibility, but the correction term you need to subtract to compute the isentropic compressibility would change it by a few percent and the value for the compressibility isn't that accurate to start with.Count Iblis (talk) 16:24, 14 July 2010 (UTC)[reply]
S does not stand for mass but entropy, [Introduction_to_entropy]. Entropy is a somewhat obscure quantity, it measures the randomness of the system, it is greatest when everything is mixed and has the same temperature.
It can never decrease in a closed system (without external influences temperatures are smoothed out and things are mixing together).--Gr8xoz (talk) 07:09, 15 July 2010 (UTC)[reply]
Oh dear, yes, of course, it's J/kg, which is indeed m2/s2. All the calculating got in the way of logical thinking, I suppose. :)
And 70 million is indeed 7 * 107, not 7 * 108. That was an error in an earlier post. Since that is squared, it brings the result down a factor 100. And of course density is (approximnately) 1 kg/L, which is 1000 kg/m3. Which brings it down a factor 1000 and I end up with your result.
So it's 1130 J/kg (or thereabouts). That's not bad at all. A human body can generate a few hundred watt of power, which means it would take just a few seconds to get 1 L of water to heat up 1 C. That's assuming 100% efficiency, so it'll be more like half a minute in practice.
This again raises the question how this value changes as the pressure rises. If it were linear, then it would take something like half an hour to get 1 L of water to a temperature where one could use it to cook a meal. Without fire! Although it would start to cool down again immediately (though less so if it stays in the thermally insulated container), but then again, one can raise the temperature even further, which is not possible with heat in a normal (open) cooking pot. It's a lot of work, but in certain circumstances, therre might be a practical use for this. DirkvdM (talk) 06:16, 15 July 2010 (UTC)[reply]
This may come across as sarcastic, but the best way is not to make it. It is a highly dangerous explosive formed by a reaction between highly dangerous acids and glycerin. Just the heat of the reaction, if uncontrolled could explode it sending you flying. C-4 is a much better explosive, if you drop it on the floor it won't blow up. It needs a detonator like lead azide or mercury fulminate to detonate it. Gunpowder is also useful. Armstrong's mixture is a highly sensitive explosive made from easily obtainable materials. CuO-Al thermite is a low explosive, but it is difficult to ignite. --Chemicalinterest (talk) 10:51, 13 July 2010 (UTC)[reply]
(EC) Have you looked at Nitroglycerine#Manufacturing? It covers the industrial angle. I don't think it's common for people to produce it for fun, because of the obvious risks. The Bojinka plot evidentally used nitroglycerine but I don't think it's a particular common explosive of choice for terrorists and such either. Nil Einne (talk) 11:19, 13 July 2010 (UTC)[reply]
Nitroglycerin is easy to make. All you need is college-level chemistry. From there, find some idiots to test your procedures at different temperature levels until you get it to work without exploding. Then, if you have and IQ over 10, which would mean that you aren't stupid enough to waste your time trying to make a weak explosive like nitroglycerin when there are much stronger explosives that are much safer to make, you will soak paper in the nitroglycerin and roll them up to make dynamite. -- kainaw™12:04, 13 July 2010 (UTC)[reply]
Hey, wait man. Didya say "weak"? I thought NG was the strongest xp around, bigger than RDX etc...
What makes you assume he wants a strong explosive? He just says he wants to know the safest and most pracical method to make nitroglycerine. He doesn't say why, which could be loads of reasons (although I think we can rule out homework).
Btw, speaking of questions we are nog supposed to answer, medical questions are among them. Questions about good ways to blow yourself up seem to be ok, though.
That might be an alternative absorbent that serves the same role in its manufacture. I was just pointing out that a stick of dynamite isn't a rolled-up tube of nitroglycerine-soaked paper, as it might appear. --Sean15:31, 13 July 2010 (UTC)[reply]
i had a black swallowtail chrysalis we found in the garden and it was alive when we found it , it was wiggling, but after i kept it in a tupperware on the porch all winter and put a few drips of water on it every few days it never hatched. so we ripped it open and it was dead. what did i do wrong????? we also ad some other catterpillars, like wooly bears, inchworms, and black swallowtails and they died too. are we cursed or what?????--98.221.179.18 (talk) 12:21, 13 July 2010 (UTC)[reply]
Speaking from having tried this with various (UK) species of butterflies and moths over a decade or so as a child/youth, it's harder than most people realise: caterpillars and pupae often need very specific foodstuffs (including the actual age and condition of the plants) and environmental conditions (like temperature and humidity) to develop to maturity, and it's not easy finding out just what these are in each case, although hobby organisations of Lepidopterists may be able to give useful advice. Try and track one down via your local library or by searching the internet.
A general aim should be to try to reproduce their ideal conditions as closely as possible, which in the case of pupae may include burying them under a light layer of soil or pinning them up by the silk pad attached to their cremaster so as to hang down from it as they would normally, depending on the usual habits of the species concerned. It's usually better to build or obtain dedicated boxes or tanks (empty aquaria are useful) rather than using small ad hoc containers - there used to be specialist companies selling such entomological equipment; I don't know if any still operate, but if they do you could consult their catalogues to see what sort of housing has been designed. Chrysalises need to be able to breath but usually do not need to be kept artificially moistened (hence, probably, your problem with that pupa), and some benefit by being placed under gentle warmth to simulate sunshine - I remember successfully hatching a large proportion of Small tortoiseshell pupae close to maturity (when you can see the wing colours through the shell) by placing them on paper on the bottom of a large (dry) fish tank under a couple of incandescent light bulbs.
A further difficulty is that many caterpillars and chrysalises are already diseased or parasitised when you find them. Bear in mind that in the wild most never make it to maturity for these and other reasons (like being predated by birds, which you can prevent) - otherwise we'd be up to our necks in the adults! Also, young caterpillars in particular often need very delicate handling - a common ploy is to pick them up gently on the tip of a small artist's brush rather than touching them directly.
Watching the development of butterflies and moths is certainly fascinating. so persevere! One warning, though, make sure you're not interfering with any locally or nationally rare species, which may well be illegal and probably bad for the species - pupils at the prep school (i.e. aged 7-11) associated with my senior school (11-18) in Kent once inadvertantly but significantly reduced the population of a rare British fritillary before older naturalists caught on. 87.81.230.195 (talk) 16:03, 13 July 2010 (UTC)[reply]
Equation
I saw this equation posted on a forum: .It looks like it has something to do with angular momentum, but I've never seen it before. Can someone expain what it means? 74.15.137.192 (talk) 14:07, 13 July 2010 (UTC)[reply]
It looks like it is something to do with relating angular momentum at different points. If would help if you linked to the forum so we can see it in context. We need to know what the variables mean if we're going to give a definitive answer (I'm just guessing at the moment based on commonly used variable names. --Tango (talk) 14:16, 13 July 2010 (UTC)[reply]
(ec) What Tango said. dLCM/dt is the time rate of change of the angular momentum vector. ω is generally an angular velocity (rate of rotation), but in the above equation it's a vector quantity (in order for it to be crossed with the L vector). We'd be better able to put the equation in context if you provided a link to the relevant discussion. TenOfAllTrades(talk) 14:23, 13 July 2010 (UTC)[reply]
Angular velocity as a vector means the magnitude is the usual rate of rotation and the direction is the axis of rotation. --Tango (talk) 15:55, 13 July 2010 (UTC)[reply]
Ah, of course. My coffee hadn't kicked in yet! I'm still not certain exactly how the formula given would/should be applied, however. It looks like it might be the change in angular momentum when you apply a torque to a rotating body around some axis other than its original axis of rotation, but context would, again, be very helpful. TenOfAllTrades(talk) 16:24, 13 July 2010 (UTC)[reply]
Unfortunately there wasn't really any context to it. Someone just posted it as his 'favorite equation', if that makes any sense. Personally, it doesn't make much sense to me, because if the angular momentum and the angular velocity happen to be parallel, then the second term just become zero. 74.15.137.192 (talk) 17:29, 13 July 2010 (UTC)[reply]
Is it dangerous or unhealthy to have a slightly elevated heart rate for a short period of time (a couple months) from a diet medication such as phentermine in a healthy adult? —Preceding unsigned comment added by 76.169.33.234 (talk) 14:36, 13 July 2010 (UTC)[reply]
That's going to depend on what constitutes 'slightly', what the resting heart rate is, what other medications are being taken, what other conditions or genetic susceptibilities that the patient has, and a host of other factors. Our article on phentermine lists some of the common side effects, as well as providing links to more extensive information. TenOfAllTrades(talk) 14:53, 13 July 2010 (UTC)[reply]
(e.c.) I'm not sure we can answer questions like that. It's not a diagnosis, but answering you wrong would be bad, so it would be irresponsible to try. You can look up tachycardia though, which is the medical term for that, and has some pretty serious effects listed there - but it depends on how fast you mean by slightly. Ariel. (talk) 14:55, 13 July 2010 (UTC)[reply]
It's not diagnosis, but it is prognosis, which is the other thing we aren't allowed to do when asked medical questions. Therefore, we cannot answer this question. A doctor, or possibly a pharmacist, needs to be consulted. --Tango (talk) 15:56, 13 July 2010 (UTC)[reply]
I understand your concern about answering the question, but I'm not taking it, I was just wondering. Of course I would talk to a doctor and get a prescription first, its just I am wondering if it is dangerous even before I go see a doctor. What if no other medications are being taken, no heart problems at all with me or any family members, and with 10-20 beats per minute increase. Also I am 22 years old and need to lose about 10-15 pounds so I am not obese. Thanks again —Preceding unsigned comment added by 76.169.33.234 (talk) 17:02, 13 July 2010 (UTC)[reply]
It isn't that people here don't want to help... it's just that what you are asking is not within the realm of what RD volunteers are capable of answering in a responsible manner. You have been given some appropriate links in the first few responses but you asked a yes/no question and, as indicated by TenOfAllTrades, there are many nuances that make it a much more complicated answer than you are hoping for. Sorry. --- Medical geneticist (talk) 17:30, 13 July 2010 (UTC)[reply]
OK, got it. As for the other factors, I was just asking in general... I did get an answer from someplace else. Thank you to everyone for the help :-) —Preceding unsigned comment added by 76.169.33.234 (talk) 02:50, 14 July 2010 (UTC)[reply]
I dont see any risk in giving general medical info as long as we are not giving medical advice. Phentermine is an amphetamine-like prescription medication used to suppress appetite. It can help weight loss by decreasing your hunger or making you feel full longer. Phentermine may be recommended if you're significantly overweight — not if you want to lose just a few pounds. Phentermine is one of the most commonly prescribed weight-loss medications, but it does have some potentially serious drawbacks. Raised BP, Nervousness and Constipation are very common. Heart rate is not a fixed number but a range which can change with age and other factors. Even for two people in the same age group, the heart rate could be different due to other factors. You havent mentioned your age or what your heart rate is. This drug, being a prescription drug, has to be prescribed to you by your doctor and Im sure he will check your heart rate, BP and other vitals. A slight increase or even a persistent increase Im sure would be recorded by him/ her and it would be appropriate that you address this issue of occasional or persistent tachycardia with your consultant. Fragrantforever 04:34, 14 July 2010 (UTC) —Preceding unsigned comment added by Fragrantforever (talk • contribs)
Stretching tapes
why do cling films and some kind of surgical and other tapes need to be stretched in order to self-adher properly? It doesn't seem to be just geometry tension and pressure but I am struggling to work out the exact adhesive mechanism/ --BozMotalk16:29, 13 July 2010 (UTC)[reply]
This may not be correct, but think of the adhesive as many tiny parallel poles covered with adhesive on the sides and nonsticky on the bottoms, where they are exposed. They are mounted on the flexible backing. When the backing is stretched, it breaks down the parallel arrangement, allowing the sticky sides to come in contact with what it is adhering to. --Chemicalinterest (talk) 12:56, 14 July 2010 (UTC)[reply]
Dark matter
Here I don't see why they think there is dark matter here. All I see is a dark ring, but dark matter does not interact with light. Is there some gravitational lensing here or something? --TheHighFinSpermWhale17:28, 13 July 2010 (UTC)[reply]
Two bodies of equal mass 1 kg are placed 1 kilometre apart in free space.Only force acting between them is gravitational force.How to find time after which the bodies will meet —Preceding unsigned comment added by 59.92.2.26 (talk) 17:59, 13 July 2010 (UTC)[reply]
Also important is initial velocities. If the bodies are stationary to begin with you will get very different answers than if they are moving relative to one another. --Jayron3223:49, 13 July 2010 (UTC)[reply]
I was kind of wondering that also. How would you get them positioned perfectly still, with no initial force in any direction? Very hard to do - almost impossible, I'd say. In effect, the question is postulating God doing it, because He can do anything. But even the most finely tuned machine is liable to have some variation in it. Maybe the teacher is hoping they won't ask that question. :) ←Baseball BugsWhat's up, Doc?carrots→ 00:10, 14 July 2010 (UTC)[reply]
They could have been placed at the specified distance in space by being tethered on a string of negligible mass which was vaporized by a laser at t=0. Certainly no initial velocity should be supposed. And what, pray tell, is "Inertial force?" The size is an interesting question. For textbook purposes, I would assume a very small radius for each mass.How would the answer vary if the objects 1 km apart were each spheres of uniform density of radius 1 mm versus 10000 km?Edison (talk) 04:42, 14 July 2010 (UTC)[reply]
The masses were stated to be one kilogram. If 10000km is incomprehensibly large for a 1 kg mass, then how about spherical masses of uniform density of 1 kg mass and 1 km diameter separated at T=0 by 1 km? Edison (talk) 03:05, 15 July 2010 (UTC)[reply]
I am surrounded by chefs and food at my workplace. Since I was employed, I've doubled my knowledge of food, fish in particular, and how to prepare it. I present to you now, or rather I ask advice on, a certain number of axioms. If anyone could please provide the scientific answers to why a chef might be inclined to do so and so, I would be most thankful. I'd hate to run around cooking and telling others to cook, without knowing the underlying scientific principles.
1) Why does meat have to rest after being cooked? Say for instance a beef is fried on pan for 6-7 minutes, then placed in the oven for 15-20 minutes, it should 'rest' (ie lie idle on a plate) approximately 10 minutes. The matter is not how long, but for what reason.
2) Is the sugary content of a meat an indication of whether or not it is good for frying on a pan? I understand to some degree the principles of the maillard reaction, but this question came up when dealing with fish: Some fish (which?) do not contain as much sugar as other, and are less subject to being fried. Haddock comes to mind as a fantastic frying fish, ditto Coalfish, whereas Trout... would that work at all?
3) Red fish filets/pieces (salmon, trout etc) can't lie flesh to flesh with white fish. Any reason?
4) To eat raw (red) meat is practically unheard of. Still whale is offered as part of our sushi. Can ordinary land-mammal meat be eaten in the same manner?
5) Some fish, especially the 'looser' ones like Cod, can not be sliced into too small pieces before being fried. This will see them fall apart, more or less. Why? Also, Haddock has a far higher tolerance, sticking more easily together during heating. What is the difference between the meat of the haddock and cod?
On #4—I don't think it's that unheard of, just not common in American cuisine. See for example steak tartar, yukhoe, other things in Category:Raw beef dishes, Carpaccio, etc. I don't know what the limitations are health-wise in terms of quality, types of animals, etc., or why fish is more common than land animals in this regard (assuming there is reason other than custom). --Mr.98 (talk) 18:15, 13 July 2010 (UTC)[reply]
I would assume that this is mostly about health. It is much more common for parasites and infections to move from one mammal to another mammal than it is for them to move from a fish to a mammal. In general, the more similar the physiology and environment of two species, then also the more likely that they can share parasites / infections. In some cases the risk might be historical than current, but cultural taboos against raw meat persist. For example, trichinella is very rare in the United States today (~25 cases / year), and yet my grandmother still insists that all pork must be thoroughly blackened for safety. Dragons flight (talk) 19:14, 13 July 2010 (UTC)[reply]
on 1: It has to do with the meat juices, which under the heat will be drawn to the surface and ultimately evaporate. If you allow the meat to cool slightly before it is eaten, these juices will make their way back towards the centre of the meat and thus the meat becomes more juicy. 2: Pan-fried trout, which is what I think you're talking about, is delicious, but it usually is fried with the skin still on. 3: never heard of it. With 4, Mr 98 is quite right that red meat can be eaten raw: in these dishes it is usually either cut extremely thinly or pulverised so that an acid (lemon juice) will "cook" the meat. I don't advise eating pork or chicken in this manner, although lamb is delicious as a Carpaccio. 5: both fish have meat which falls into thick slices naturally, though cod is thicker. --TammyMoet (talk) 19:17, 13 July 2010 (UTC)[reply]
(ec) To #1, 'resting' meat serves two purposes. First, it is supposed to allow for the meat to reabsorb some of its juices before you start hacking away at it with a carving knife. Second (and most important) it provides for more even cooking. In the cooking process that you describe above, a piece of meat is pan fried/seared rapidly for a few minutes to create a tasty, browned crust on the exterior. It is then oven roasted for a period of time — several minutes up to a few hours, depending on size.
Thicker pieces of meat require more cooking time, as it takes longer for the externally applied heat to reach the center of the cut. Even then, remember that the temperature isn't uniform all the way; there will be a temperature gradient through the meat. The outside will be hottest (as it is directly exposed to the hot air in the oven), while the center of the meat will be coolest. At the moment that you take the meat out of the oven, it might well be 'medium' at the surface, but 'rare' at its core. During the ten to twenty minutes (or even more!) of 'resting', the hotter outer layers of the meat will have the chance to transfer some of their heat to the inner parts, while they themselves cool off a bit. The result is that the meat comes to a more uniform temperature – and degree of doneness – throughout. TenOfAllTrades(talk) 19:29, 13 July 2010 (UTC)[reply]
For #2, are you referring to pan-frying or immersion frying? Trout and salmon are rarely deep-fried, but it's not due to the sugar content - it's the fat. Both are very fatty fish and the addition of oily batter just makes it even fattier. Deep-fried salmon also tastes more muted, as if the neutral cooking oil was wiping out the flavour of the fish oil. There may also be problems with poor adhesion of the batter to oilier fish. Matt Deres (talk) 14:38, 14 July 2010 (UTC)[reply]
My take on this is that the temperature of the piece of it evens out and the denatured proteins have a chance to relax and settle back down to some equilibrium. Perhaps this have something similar to the fact that when you prepare a dairy ice cream mix you should ideally let it settle down (preferably overnight) before churning.
Fried fish is good in a different way than say fried steak. The former has most of the Maillard and caramalization rxns on its batter or coating while the latter has it directly on the meat surface. That being said, pan-frying fish with a very slight addition of sugar is quite fantastic due to the promotion of Maillard type rxns and is indeed practiced in many cuisines. Pan fried meats have a similar enhancement effect when the meat has been treated with sugars.
Maybe because the colour may bleed across? Try it and see why not, maybe it's one of those silly food myth like that no-cheese-with-seafood-pasta-sauces "rule"
Yes. Beef carpaccio or tartar can be fun sushi style, but I don't usually eat it due to sanitary risks.
This may be due to the different amount of connective tissues in different fish types, with some have more collagen between each muscle group (a "flake") than others
I've read the article Cat, and have learnt that cats don't see red. I'm after more detail, though, and I know their sight is more acute than humans. What frequency ranges do they typically see? I do have a reason for asking this besides curiosity :) --TammyMoet (talk) 18:10, 13 July 2010 (UTC)[reply]
Cool thanks! Wish I could understand it! Joking aside, how does this 510nm peak sensitivity compare with human vision? Does it mean they can see what we know as ultra-violet? --TammyMoet (talk) 19:09, 13 July 2010 (UTC)[reply]
Note that the peak sensitivity is the frequency/wavelength at which the sensitivity is highest, not the highest frequency/wavelength at which there is any sensitivity. What the article abstract appears to say is that cats have cones similar to human S and M cones, but there's also evidence of a third cone type in between those (peaking around 520 nm), which was only active in dark (scotopic) conditions. They also have rods similar to human rods, which peak around 500 nm but aren't shown on the image that Ariel linked. That would mean they have color vision similar to a human protanope ("red-blind") in the daytime, but might also have some nighttime color discrimination (unlike humans). -- BenRG (talk) 20:30, 13 July 2010 (UTC)[reply]
There is a difference between not being able to see red and not being able to distinguish red from other colours. As far as I can tell (I can't understand the paper Cuddlyable links to much more than you can), cats can see roughly the same range of wavelengths are we can, but they have slightly different abilities to distinguish certain wavelengths and combinations of wavelengths (for example, humans can't distinguish between yellow light and a combination of red and green light, cat's might be able to, I'm not sure of the details). --Tango (talk) 21:10, 13 July 2010 (UTC)[reply]
The deal is with how many different kinds of color receptor they have. Being sensitive to red - and being able to distinguish red from (say) green are two very different things. Humans have three kinds of color receptor - which are most sensitive to red, green and blue respectively. When we see pure yellow light, both the red and green receptors respond (although less strongly than they do to red and green) - so we can see yellow light, but we can't tell whether it really is yellow (like a yellow sodium street lamp) or whether it's a mixture of red and green (like a picture of a yellow sodium street light displayed on a TV screen). We think TV pictures look realistic because they show pretty much all the colors we can see - but in truth, they aren't.
Cat's only have two kinds of color receptors - one sees green and the other violet-ish blue. That means that to a cat, red and green look exactly the same. Red and yellow things don't look black (like, for example, infra-red looks to us) - they look green. They may be able to distinguish shades of violet, blue and cyan better than we do (it's hard to tell) - but they are useless at distinguishing orange, yellow and red from green. It's more or less true to say that they are red/green color-blind.
By contrast, (weirdly) goldfish have amazing color vision - with many more color receptors than us. There are species of shrimp with even better still - some have as many as 14 different color receptors - and for them, the yellow "color" put out by a computer screen would look violently different from the yellow put out by a sodium lamp. Not just a little bit different...consider how much different a frequency that's midway between red and blue (ie, green) looks from a mixture of red+blue to us. For a goldfish, those two kinds of yellow (red+green and halfway-between-red-and-green) probably look as different as magenta (red+blue) and green (halfway between red and blue) looks to us!
It is widely believed that the reason we are able to see shades of red/yellow/orange/green is because we've evolved to eat fruit - and the difference between an unripe and a ripe fruit is typically some change in color between red (ripe) and green (unripe). Cats are carnivores - and whether that poor little mouse is spurting red, yellow or green blood is of very little concern to them!
Fascinating fact: from the mantis shrimp article: "[T]he mantis shrimp‘s eye is made up of six rows of specialized ommatidia. Four rows carry 16 differing sorts of photoreceptor pigments, 12 for colour sensitivity, others for colour filtering. ... [I]t can perceive both polarized light, and hyperspectralcolour vision [and] permit both serial and parallel analysis of visual stimuli." Those are some serious eyes! – ClockworkSoul14:09, 15 July 2010 (UTC)[reply]
Pressure of Deepwater Horizon Oil Leak
The Deepwater Horizon Oil Leak is about 1500 m below sea level. At that level, the absolute pressure is about 1.52e7 Pa. Does anyone know what is the pressure of the oil leak? I wonder how the leak is able to overcome the absolute pressure at that level.Inkan1969 (talk) 18:59, 13 July 2010 (UTC)[reply]
Thanks for the picture and the number, Ariel. The picture doesn't correspond to your number though; it reads only 250 psi. Anyway, I see now that the leak can overcome the absolute water pressure as its own pressure is double the value. Inkan1969 (talk) 19:58, 13 July 2010 (UTC)[reply]
It's low because the pipe is open. Once they seal it the pressure will rise. I linked it to show the pressure range they are expecting. Ariel. (talk) 21:08, 13 July 2010 (UTC)[reply]
If you follow Ariel's link, you'll see that the pressure at the end of the pipe is only ~2250 psi (15.5 MPa), i.e. only slightly above the pressure of the ambient sea water (at least prior to the capping exercises). This isn't surprising since the flow has been largely unconstrained, so there is no reason for a high pressure to accumulate. One can predict the flow rate from the pressure difference and vice versa. If a 50 cm diameter pipe is belching 50000 barrels a day, then that's less than 1 mph in flow velocity and requires only about 100 Pa of overpressure at the exit. That's actually hardly anything. If it were accessible, a single man with a stout piece of plywood could temporarily block that off. However, that's not the real issue. The oil is being forced out of the ground by the partial weight of the Earth above the oil pocket, and if you attempt to block it, the pressure at the well head will rapidly build. Ariel's link also shows this very well, indicating a pressure in the well bore of 4400 psi, nearly double that of the ambient water. And if one tried to close all of the openings through which oil is currently escaping or being collected, you'd have to be able to resist at least that much pressure and possibly even significantly higher pressures. Dragons flight (talk) 20:19, 13 July 2010 (UTC)[reply]
The leak is 5000' below the surface of the water - but the oil reservoir is 18,000' below that! So the oil is being pushed down on by 18,000 feet of solid rock - creating pressure many times that of the water at 5,000 feet - but when the pipeline between the reservoir and ocean meet, the oil will expand outwards until the pressures are equalized - which is why the pressure gauge is reading so low. However, when the well is capped, the pipe will have to withstand the full pressure of 18,000 feet of rock...and that's the big concern here. If the pipe was weakened or cracked by all the torment it's been through - then capping it could cause it to break in a big way and allow this incredible oil pressure to force it's way out though cracks and fissures in the rock at the sea floor - resulting in a much greater problem. It's frustrating that the process to cap this thing is so slow - but not making matters worse than they already are is a prime concern here. SteveBaker (talk) 13:56, 14 July 2010 (UTC)[reply]
How do you know that most of the weight of the rock above isn't transferred to the rock substrate on either side of the pocket? I have been deep in the earth in a gold mine and in a cave, and in neither case was I under any pressure at all from the many meters of rock and dirt overhead. So it may be incorrect to assume that a pocket of oil 18000 feet below the surface is pressurized by the weight of all the rock. Rock is very good at transferring weight around a void. It is not necessarily a plastic fluid like mud, which would tend to fill voids. If we take the density of rock to be about three times that of water, then the pressure from 18000 feet of rock would be about 24000 pounds per square inch, or 3 times the pressure from a column of water of 18000 feet. How thick would the steel well casing and cap of an ordinary oil well have to be to contain it? Edison (talk) 18:17, 14 July 2010 (UTC)[reply]
Rock and dirt can be self-supporting over relatively small spans (50 to 100 feet maybe) - but this oil reservoir contains billions of gallons of oil. It's gigantic compared to the kinds of cave you've been in - tens to hundreds of kilometers across. Oil reserves aren't exactly like a big cave filled with liquid - they are actually present in sponge-like porous structures with about 60% rock/dirt/sand/mud and 40% oil. So imagine an oil soaked sponge with an anvil placed on top of it and you have the mental model about right. SteveBaker (talk) 23:03, 14 July 2010 (UTC)[reply]
All somewhat plausible, but oil under that much pressure beyond the hydrostatic pressure at the pipe opening should squirt out orders of magnitude faster than was seen. And there must be an impervious hard dome of rock besides fluid sand/mud or the lower density of the oil compared to mud or water would cause it to rise to the surface without any drilling. In other words, it requires a hardrock dome to keep it in. Edison (talk) 03:00, 15 July 2010 (UTC)[reply]
"Hooke discovered that the catenary is the ideal curve for an arch of uniform density and thickness which supports only its own weight."? 74.15.137.192 (talk) 01:56, 14 July 2010 (UTC)[reply]
You have to define "ideal" (Greatest enclosed space? Most pleasing to the eye? Greatest supported load for a given span?) If you keep reading in the inverted catenary arch article to see what "ideal" means in this case: "the [unloaded inverted caternary] arch endures almost pure compression, in which no significant bending moment occurs inside the material. If the arch is made of individual elements (e.g., stones) whose contacting surfaces are perpendicular to the curve of the arch, no significant shear [e.g. slipping] forces are present at these contacting surfaces." The Mathematics Reference Desk might be able to assist you in setting up the appropriate equations to demonstrate this is the case, if you are so interested. -- 174.24.195.56 (talk) 02:48, 14 July 2010 (UTC)[reply]
"Which supports only its own weight" strongly suggests, to me at least, that it's not "ideal" for practical purposes. — Lomn13:59, 14 July 2010 (UTC)[reply]
The force in walls should go down the walls otherwise it will buckle. A catenary is the shape a uniform chain will take when hung therefore if that shape is inverted the forces will go directly along the line of the chain. Antoni Gaudí used nets with weights attached to design the shapes of the walls for some of his designs - the finished building is then the same shape as the net turned upside down. Dmcq (talk) 10:07, 15 July 2010 (UTC)[reply]
Because if the force on any little section of strong pulled out of that line, there would be an imbalance between that and the tension in the string (which can't help but run along the length of it). That imbalance would cause the string to move - hence, when friction gradually damps down the motion, the only shape the string can take is one where all of the forces are perfectly balanced and run exactly down the line of the string. Turn this upside down (or just mentally flip the gravitational vector) and you have an arch where all of the forces run down the center of the span...which is (in at least one sense) "perfect". SteveBaker (talk) 20:26, 15 July 2010 (UTC)[reply]
animal feelings
do animals like horses ever get bored? some people say that certain expressions show boredom but others say that theyre not like humans and dont get bored. im stuck!!! —Preceding unsigned comment added by 98.221.179.18 (talk) 20:57, 13 July 2010 (UTC)[reply]
It's a difficult question. Animals certainly have feelings of some kind, but it's hard to say to what extent they are comparable to human feelings. It's a matter of definition, really. Animals kept in captivity in conditions where they have very little stimulation often end up going round and round in circles, which could easily be interpreted as boredom. --Tango (talk) 21:03, 13 July 2010 (UTC)[reply]
We can measure levels of anxiety, brain activity, and things like that in animals. Animals without certain types of stimulation can get quite listless and their health can suffer. Some animals (e.g. fish in a tank) don't seem to care very much. You might find Temple Grandin's book Animals in Translation particularly interesting along these lines. --Mr.98 (talk) 21:06, 13 July 2010 (UTC)[reply]
Animals can certainly display neurological and behavioral problems from a lack of mental stimulation. Whether you can call this "boredom" is perhaps debatable, but the Wikipedia article on Stereotypy#In animals describes some common symptoms in animals from what can be described as "extreme boredom". --Jayron3223:47, 13 July 2010 (UTC)[reply]
Domesticated animals of many kinds show behavior that's symptomatic of lack of stimulation (which I guess is "boredom"). Dogs chase their tails, parrots pull out their feathers, zoo and farm animals exhibit repetitive behavior, humans get cabin fever. All of these things "go away" when the animal has some kind of stimulation. It's pretty clear though that animals with smaller brains and less active life-styles don't have these problems. Many hunters (like maybe crocodiles) can stay perfectly still for days without evident problems. I suspect the deal is that some animals have evolved to lay in wait - or to conserve energy by staying dormant, where others are 'wired' to use every spare moment of their day productively. This evolutionary trait is what allows some to sit around and do nothing whatever without "getting bored" while the others are likely to suffer mental issues if prevented from doing what their brain chemistry is frantically trying to make them do. SteveBaker (talk) 13:19, 14 July 2010 (UTC)[reply]
most of the animals I see in the zoo appear very bored and unwell.Fragrantforever 04:24, 14 July 2010 (UTC) —Preceding unsigned comment added by Fragrantforever (talk • contribs)
The above answers dealing with caged animals pacing in circles: can someone PLEASE correct the ignorance evident in the explanations for this common phenomenon? 63.17.82.101 (talk) 10:30, 14 July 2010 (UTC)[reply]
Well, you could correct it. What, specifically, do you think is incorrect in the explanations? What evidence do you have for that claim? We're all about dispelling ignorance around here! SteveBaker (talk) 13:41, 14 July 2010 (UTC)[reply]
ignorance??? well, #1 what is scientific about evolution. if you have a bunch of screws and sheetrock will it form a house if u let it sit around for years?? no! its completely unscientific. and #2 how, in the big bang, did the first particle of matter form before the big bang occurred?? things just cant appear! And how can so many accidents happen as to make such a complex and intricate world such as we are living in today? people still dont even understand the human brain completely! are u stumped yet???--Horseluv10 (talk) 01:09, 15 July 2010 (UTC)[reply]
That's an extremely naive view of evolution and you need to stop and think before spouting off whatever your parents or religious leaders are telling you.
If screws and sheetrock were capable of (a) reproducing, (b) passing on features of parent onto child and (c) mutation - then they would indeed evolve...although not necessarily to form a house! However, since they fail on all three counts so evolutionary theory simply doesn't apply to them. This is not a valid analogy. I might as well say that screws and sheetrock can't have children - and so neither can humans. It's a really dumb analogy!
Evolutionary theory has been carefully tested using scientific principles - and from everything we have learned as a result, it's extremely scientific...possibly one of the top five most reliable scientific theories we have.
We don't know how the singularity that started the big bang was formed - but things most certainly can 'just appear'. Read Quantum fluctuation and virtual particle. "Just appearing" is actually one possible way that the universe could have formed.
The way "so many accidents" could happen is that the universe has been around for 13 billion years and is at least 46 billion light years across. The number of times that something incredible could happen in all of that space and time pretty much guarantees that it will happen. It may be really unlikely that you could roll ten sixes on ten dice in a single roll - but if you keep rolling those same ten dice once every 10 seconds, day and night you'll see it happen about once every 20 years. If everyone in the world rolls ten dice, then it'll happen about 100 times on the very first try. If you wait for 13 billion years and have every cubic centimeter of every planet in the 46 billion-light-year sphere that is the visible universe "roll dice" then once in a while, all of the right chemicals will come together in the right place at the right time to make a teeny-tiny self-replicating molecule. Once you have that, evolution will push things along to where there are complex animals like people.
But it's even more than that...suppose you have a bucket with 1000 dice in it. The chances of rolling 1000 sixes is so unlikely that you'd never do it even once. But if you were allowed to keep the sixes from each roll then after about 60 rolls - you have all sixes. That's how evolution works. Sure, all of the genes are randomly scrambled - but the good ones, the ones that make animals and plants better at survival are kept and pass on to the next generation. That gradual accumulation of good genes and discarding of bad one is what gets you 1000 sixes. A failure to understand this simple and easy-to-understand thing is at the heart of all of the idiots who don't believe evolution is real. So open your eyes and your brain before opening your mouth.
well i dont get what im saying from my parents of anything. im getting it from common sense. another proof that contradicts evolution is no missing links have been found. there is no evidence in the fossil record that the animals changed into different animals and animals into man. the geologic column is all fake and hypothetical and mutations never produce new organisms, so.... how do poeple know that things are billions of years old? where's the PROOF. dont forget part of the scientific method is OBSERVATION. there are no records of evolution happening so where did it come from? A failure to understand this simple and easy-to-understand thing is at the heart of all of the idiots who don't believe creation is real. So open your eyes and your brain before opening your mouth.--Horseluv10 (talk) 20:48, 15 July 2010 (UTC)[reply]
Dear Horseluv, if you want to open your eyes and exercise the brain God gave you, take a look at this archive of information. The whole site is good, and explains things simply or in great detail, depending on how much detail you want. Even if you are unconvinced, you will be able to avoid making arguments based on untruths, since you will know they are untrue. The truth will set you free! :) I suggest that any further discussion on this topic at this point is unlikely to throw up much useful, nor to make anyone think very highly of other people's beliefs. So probably best to drop it. 86.163.212.254 (talk) 22:17, 15 July 2010 (UTC)[reply]
The fossils of rocks show the layers from the Flood. There are no links to prove the changing of species. Even if there was, which there isn't, it doesn't show adequate evidence. Evolution is what God-haters, Bible-despisers believe. Creation is accepted by me and evolution is thrown out the door. YOu can never convince me to believe I'm a kin of a monkey or any of that piffle. Insane!!!!!!!!Ridiculous!!!!!!!!!Idiotic!! —Preceding unsigned comment added by Diver62 (talk • contribs) 23:06, 15 July 2010 (UTC)[reply]
There are always small amounts of drug resistant bacteria. They are not as strong as the normal bacteria, keeping the population normally at a minimum. When the drug kills the normal bacteria, suddenly the competition is gone, and the resistant bacteria can thrive and multiply. This also explains why bacteria were not drug resistant long ago; the normal bacteria crowded them out. --Chemicalinterest (talk) 11:25, 16 July 2010 (UTC)[reply]
Which is evolution...more or less. "Less" because (I presume) you are denying that the bacteria can change over time (and thereby create new species) and that instead, God created enough drug-resistant bacteria to allow them to 'bounce back' after we administer an antibiotic.
The only problem with that is this: Suppose we think about TWO drugs - we administer one, then we wait for the bacterial population to grow back from the few survivors - then we administer the second one. That's pretty much what happens in a hospital - you try one drug, and if the bacteria are resistant to it, you try something else.
In your idea of things, the first drug ('A') kills off all of the bacteria except the very few who have natural resistance to that drug - who survive and pass that trait onto their offspring. That's OK - that's what evolutionary science says will happen. But now, suppose we add a second drug ('B'). Since we already killed off all the bacteria who might have had immunity to B but not A in our first treatment, in your view of things, the only survivors are the ones who were originally immune to both A and B - right? Well, maybe that's possible - if one in a million of the original bacteria were immune to drug A and one in a million to drug B then statistically, one in a million-million would be resistant to both. Fair enough...there are easily a trillion bacteria floating around in a typical hospital.
But suppose we try three drugs in succession. Are there bacteria that are immune to A, B and C? Well, maybe. But there must also be bacteria that are immune to only A, only B, only C, A and B, B and C, A and C...as well as the lucky ones who are immune to all three and the unlucky ones that are killed by any of them. We know that because if (for example) we had started with drug B, then C, then A - we'd have seen bacteria die off at each stage. So we know that there are at least 8 different kinds of bacteria in the original set.
However, some disease bacteria have become immune to HUNDREDS of drugs (we're running out of drugs to treat TB for example). The numbers of naturally resistant bacteria that god would have had to create to allow for at least one bacteria to be resistant to every possible combination of every drug that humans might possibly think of, now or in the future, is crazy! There is no way that there exists a viable number of bacteria with built-in resistance to all 500 different antibiotic drugs, plus some that are resistant to only 499 of them, and some that are resistant to a different 499 of them and some that only have resistance to every combination of 498 of them...and every combination of 342 of them...and just one of them...and none of them. There are just too many permutations and combinations - even if there were only one bacteria of each kind - there aren't enough of them on the entire planet to have even one with every possibly combination of immunities. The number of bacteria god would have had to create to produce the effects that we actually see in real hospitals would be 500 factorial (500! in mathematical notation) which is an ungodly large number...something like 101,200. There are only around 1082 atoms in the entire universe - so there certainly aren't enough bacteria to be immune to every possible combination of 500 different antibiotics...and that's what has to be true for your theory to be correct.
So it absolutely MUST be the case that the bacteria are CHANGING. You're right about how a few survive the first drug - but then, as the population grows, some source of change is affecting their DNA, scrambling it up and creating bacteria with a natural resistance to the second drug. We know that this mechanism could be radiation or various chemicals or it could be errors in the DNA copying mechanism in their cells.
Only if the bacteria can CHANGE can we possibly see the results that we are seeing, every day, in hospitals around the world. Once you admit the possibility of change - you have new species (with new DNA) that didn't exist "in the garden of eden" - hence not all species are created by god - hence evolutionary theory is true and hence all of that crap you read in the bible is pure fiction.
So, you see, this business of drug-resistant diseases IS conclusive proof of evolution in action. You really can see entire new species develop - and you can do it without needing to look at fossils or to date things back millions of years (although that works too - and provides another means for proving that evolution is true). SteveBaker (talk) 13:18, 16 July 2010 (UTC)[reply]
Did you read everything correctly? You should be the one being convinced that EVOLUTION IS REAL! Between fossil records, comparative cytology, comparative anatomy, comparative embryology, and comparative biochemistry, it should be obvious to you the evolution is a real thing! If you want observations of evolution in action to prove its existence, look antibiotic resistance and peppered moth evolution!
Seek ye the answer about whether horses get bored in the truth of the Bible! Creationists will help you find Biblical horses and there are many asses among them. The Bible must be true when it says that an ass can speak so I asked a horse whether it was boring to be a horse. The horse answered Nay. Cuddlyable3 (talk) 14:21, 16 July 2010 (UTC)[reply]
I feel like correcting your grammar; it is Neigh. The Bible states the the ass spoke to Balaam. That was a miracle by God. A simple definition of a miracle is something we do not understand. If a computer could think, it would think that changing its OS is a miracle since it can't do it and it doesn't know how to. --Chemicalinterest (talk) 14:33, 16 July 2010 (UTC)[reply]
(e.c)S. Baker inserted his comment after Diver62 inserted theirs. There is no denying that species do change, but the change is not helpful. For example, if you always shovel dirt for a living, you will get calluses on your hand. Calluses are a reaction to stimuli, just as bacteria have their reaction to stimuli. But a callus has its disadvantages; the nerve endings are dulled, the skin does not look aesthetically pleasing, for examples. Some people can survive on very little food and not feel faint all of the time. If an ordinary person ate that much food, they would feel very tired all the time and not be able to do a day's work. This survival capability may be an advantage on one way (when less food is available), but the victim's health is impaired. They are very thin and do not get enough nutrition. Is that evolution? No. It is a survival instinct. Even though these are not changes to genes, they show how seemingly advantageous changes to a living creature really harm it. Normally, resistant bacteria are only living with difficulty, on the verge of extinction. Natural selection (which is a true concept) will kill the weaker drug-resistant germs and allow the stronger ordinary bacteria to live. But drugs are a stress, which changes natural selection around. Now the drug-resistant germs are more prone to survive, while the ordinary bacteria die. It is the same as Le Chatelier's principle in biological form.
Your calculations are trying to disprove my opinion (yes that's what it is, I am not a bacterium that patrols others and asks them what is going on), but they seem to disprove yours too. If they are constantly changing, then there still needs to be all of those different bacteria types. Bacterium(B)1 is resistant to drug(d)1, while b2-b1000 are not. B2-B1000 die, and B1 survives. It multiplies. Now D2 is tried on it. B1's descendants, are all killed, except for one, B351. It survives and multiplies. Now D3 is tried... It could go on forever, and there still needs to be so many bacteria; more bacteria than atoms in the universe. If the "evolution" is happening, it would be very fast; 500 good mutations in 100 years. That is much faster than "normal" evolution.
Bacteria are extremely complicated for their size. One little difference would require a large amount of change. Also, a small amount of bacteria cannot infect someone easily, making a delay in the observation that they are resistant to drugs until their numbers have grown.
Until bacteria can be observed directly (e.g. by comparing the DNA of a normal one to the DNA of a disease-resistant one), the idea is mostly a matter of speculation on how it happens.
An example in human life is the quality of drinking water. Humans born in highly developed countries have a much lower tolerance for bacteria in their drinking water. When they drink water that people in underdeveloped countries drink, they get gastrointestinal problems. But the residents of the country drink the water without harm. This is not mutation; it is reaction to stimuli. A very simple example would be the iris of an eyeball; the more light shines in the eye, the smaller the pupil gets as a reaction to stimuli. It does not always have to be in the DNA. The drug could be having an unknown effect on the bacteria. It isn't strange; many chemicals' effects on humans are not fully understood. Just some thoughts. Sorry for the lengthy post. --Chemicalinterest (talk) 14:30, 16 July 2010 (UTC)[reply]
The changes you are talking about are changes to an individual organsim, not the species. A reaction to stimuli and evolution are not the same thing! For instance, using your example of calluses, if a person shovels dirt all their life and develops them, you are right, that isn't evolution, but not because evolution doesn't exist like you seem to think, but because it isn't a genetic trait that gets passed on to the offspring. Your example of calluses is invalid because it is a pysical change to one organism that doesn't get passed on to offspring.--74.67.89.61 (talk) 00:04, 17 July 2010 (UTC)[reply]
shame on you "cuddyable" for mocking God's Word, the Bible!--Horseluv10 18:17, 16 July 2010 (UTC)
Horseluv10, for some horses in the Bible please look at Ps 38:17, Ps 147:10, Re 19:11, De 17:16, Es 6:8, Isa 31:1, Jer 51:21. For some asses in the Bible please look at Nu 22:28 which alleges God talks out of His ass, Nu 31:28, Zec 9:9, Nu 22:23, Jg 5:10, 15:15, Mt 21:5. Then you may check your biblical knowledge at www.evilbible.com . My name like yours includes a number so please get that right. Cuddlyable3 (talk) 00:45, 17 July 2010 (UTC)[reply]
Are you aware of E. coli long-term evolution experiment? Or even the Luria–Delbrück experiment (a perhaps better explaination [8])? BTW Full genome sequencing of bacterium has been done many times and isn't exactly that difficult nowadays, see List of sequenced bacterial genomes. Of course antibiotic resistance is often in the plasmid anyway. BTW you seem extremely confused if you say '500 good mutations in 100 years. That is much faster than "normal" evolution'. Rather then come up with my own explaination a quick search finds [9] "For example, in your intestine there are billions and billions of bacteria. This means that every day these bacteria accumulate millions of mutations. That’s why there’s a great danger of developing drug resistance in a very short time." To put it bluntly, your statements suggest you don't understand evolution, nor the basics around it at all. (For starters, there's no such thing as a 'good mutation'. A mutation for antibiotic resistance would often have a negative effect, except when there happens to be antibiotics.)
BTW, in terms of the comment above about speciation, it is unfortunate you didn't puruse the helpful link 86 gave above where you'll see we have in fact observed it as discussed at [10][11]. (If those sites are blocked, ask your parents to allow them thorough, they're much more tame then wikipedia and since your parents are happy for you to think for yourself they won't I presume have a problem with the content.) Those also discuss why it's a bad idea to discuss it when it related to bacteria anyway, where species is a very fussy concept (more so then with complex multicellular organism where it's still problematic as we've discussed before. As 86 said, that also dispels many other myths such as several repeated above about missing links and the fossil record.
How is it like diving 600 feet underwater? what kind of marine life is down there? Are there coral reefs, sea slugs, moray eels, stonefish, or dolphins? I'd go scuba diving now if i could.--Diver62 (talk) 00:06, 14 July 2010 (UTC)[reply]
Me, too. You picked an interesting depth because the Photic zone goes down to a maximum of around 200 meters, or around 660 feet — below this, it is very very dark, and photosynthesis cannot occur; bioluminescence is essentially the only light available. So, in addition to the fact you're an technical diver at this point because of the crushing pressure, you're going to be carrying around a lot of flashlight gear. Comet Tuttle (talk) 00:26, 14 July 2010 (UTC)[reply]
did u ever go diving before? i'm just a highschool teen and i'm interested in going for cetology and marine biology in college. i also want to go diving as a profesional and be diver in caverns and wrecks. do u have similiar interests? i even wrote a 6-page short story of my future life of diving in the red sea. the beautiful creation of God underwater, diving in a cavern, almost killed by an octopus, and losing our air and rope. it is also about wreck diving and finding treasures and seeing squid crushing fish in the window of a sunken ship. that's my type of life! —Preceding unsigned comment added by Diver62 (talk • contribs) 00:59, 14 July 2010 (UTC)[reply]
I've seen on the internet of an octopus taking someone's underwater camera from them and swimming away with it. I just wrote it in the story for excitement, even though it may not be true. I like octopuses and dolphins especially.I also like police, detectives, and karate. Even though I want to do karate, I don't do it. I'll hopefully do it when I'm grownup. —Preceding unsigned comment added by Diver62 (talk • contribs) 11:12, 14 July 2010 (UTC)[reply]
People have dived 1,083 feet being the record on scuba gear! Isn't that amazing! All that pressure is upon you in such a deep, dark,area full of lantern-fish! —Preceding unsigned comment added by Diver62 (talk • contribs) 15:19, 14 July 2010 (UTC)[reply]
Trevor Jackson dived 600 feet and explored a ship wreck. That is a deep dive and maybe the deepest I would dive. there is also a danger of the bends, nitrogen narcosis, oxygen toxity, and related troubles down there i wouldn't ever want to deal with. —Preceding unsigned comment added by Diver62 (talk • contribs) 15:34, 14 July 2010 (UTC)[reply]
Worth noting is that those really deep dives are interesting as technical accomplishments, rather than as exploration or entertainment. Under those pressures, one incurs tremendous amounts of time in decompression (up to twelve hours) at multiple depths and with multiple gas mixtures, in exchange for at most a few minutes of bottom time. It's also an extraordinarily risky pursuit — of the nine people (all men) who have made dives to at least 800 feet, at least three have subsequently been killed in diving mishaps. Even 600-foot dives are quite risky, costly, and time-consuming.
Truth be told, if you're just hoping to see interesting underwater sights – including coral reefs, sea slugs, moray eels, stonefish, or dolphins – you're probably better off staying within a hundred feet of the surface. You save all the technical mucking about and can spend hours exploring the sea. TenOfAllTrades(talk) 15:55, 14 July 2010 (UTC)[reply]
Sure thing. That is a good point you brought out. I like to see all the paraphernalia of the sea, but also like to explore the caves, caverns, shipwrecks, and just go deep for the fun of it. I might even be a police diver someday, since i like police,or live in a submarine. Whatever God has for my life is the best thing, and that's what i'll do. —Preceding unsigned comment added by Diver62 (talk • contribs) 16:39, 14 July 2010 (UTC)[reply]
Can you see coral forming? Like, one year its small, and the next year it is 1/2 inch bigger. i thought it grows slow, but some trained divers maybe check the coral. what's the answer? PLEASE, I NEED AN ANSWER!!!!!!!!!!!!!!!!Diver62 (talk) 10:44, 15 July 2010 (UTC)[reply]
There are many, many different kinds of coral, and they all grow at different rates. But the answer to your question is yes, for some corals. I try to spend a week diving in Tenerife each year, and there's a bay with volcanic rock sticking out of the sand at about 30 feet of depth. Each year since about 2000, I've seen a few small patches of coral there getting a little bit bigger. Tenerife is geographically near the extreme of where you might expect to find that sort of coral, but it does seem to suggest that its average water temperature is getting very slightly warmer. But no more shouting, please :) --RexxS (talk) 21:48, 15 July 2010 (UTC)[reply]
THanks. I finally got my question answered. Wow! You're fortunate you can go diving every year. Can I come with you? I hope no El Nino's come with warm currents and kill all the precious coral. How much bigger and what color is the coral???Diver62 (talk) 00:43, 16 July 2010 (UTC) —Preceding unsigned comment added by Diver62 (talk • contribs) 00:43, 16 July 2010 (UTC)[reply]
M998 (the most common military vehicle called a HMMWV, "Humm-Vee", or "Hummer") is not at all like a commercial "Hummer", "H2" or "H3." The M998 is a sort of pipe-framed chassis supporting a canvas buggy powered by an eight-cylinder diesel engine; it has four-wheel independent suspension, four-wheel independent drive, a water-proof, bullet-resistant engine block, and for the most part would not be considered "safe" by NTSB standards as a civilian vehicle. The Hummer as it was commercially sold was a Chevy Tahoe with a customized fibreglass hull that marginally "looked like" an M998 (in my opinion, they are not even close, especially not in profile view: M998 vs. H3). It is not fair to call them the same vehicle at all. Nowadays, the need for a light troop transport has been largely replaced by the need for armored vehicles and MRAP, so it is probable that the HMMWV and its brethren will see very limited use on the next generation battlefield. They were never intended as "combat vehicles" (though many models did have light armament, they were intended as transports), and one of the great controversies during the early stages of the Iraq War was that American soldiers were being ferried into combat zones in unarmored HMMWVs. Nimur (talk) 22:30, 14 July 2010 (UTC)[reply]
Its completely unfair to compare the H3 to the M998. The H3 was not intended to resemble the military version, except perhaps in the grille. The H1 compares much more favorably in styling and build to its military cousin. See this pic instead of the H3 one you placed above. --Jayron3222:53, 14 July 2010 (UTC)[reply]
The Hummer H1 was a street-legal version of the HMMWV -- same frame, same drivetrain, same lousy suspension, same major body panels, and some of the same special features, and they both came off the same assembly line. The Hummer H2 was a standard GM SUV frame styled to look somewhat like the H1. The Hummer H3 was a SUV that bears a passing resemblance to an H1. --Carnildo (talk) 23:57, 14 July 2010 (UTC)[reply]
Yeah - the H2 is a Chevvy Tahoe with different body panels - and not much else! The H1 is the only one that bears any resemblance to the military vehicle - and even then, they dumbed it down a lot. SteveBaker (talk) 19:33, 15 July 2010 (UTC)[reply]
poor bees
around the hottest time of the summer, the bumble bees start acting very wierd. they stay on the plants at night and dont fly back to their nests. sometimes they dont eat too. then the other day i saw about 7 of them lying dead in the stones by our house. are they dehydrated perhaps???? or tired?? i cant find an answer anywhere else. thanks for answering--98.221.179.18 (talk) 00:59, 14 July 2010 (UTC)[reply]
Contact your local university. Maybe they would be interesting in analyzing one of the dead ones. I doubt they would be dehydrated unless there were no flowers. Tired is unlikely too. Is it possible it's mating season, and you are seeing the dead drones, and the new queens who didn't make a hive? Ariel. (talk) 09:19, 14 July 2010 (UTC)[reply]
On a similar topic, I occasionally see bumble bees apparently trying to burrow into the lawn. What are they seeking? Dbfirs09:10, 16 July 2010 (UTC)[reply]
we have these bees that are like bumblebees but theyre much bigger like three times the size and they have shiny black abdomens, not furry like bumblebees. we thouught they are carpenter bees but they gather pollen like other bees and i never see them chew wood. most books say they are carpenter bees but i dont think so. are they queen bees of some sort??? then there's some very, very tiny bumblebees that are half the normal size of a bee. i dont know!!!!--98.221.179.18 (talk) 01:03, 14 July 2010 (UTC)[reply]
Carpenter bees do collect pollen and nectar, and they fit the description; so your "big bumblebees" are probably carpenter bees indeed. You need to find where they make their tunnels in order to see or hear them "chew wood" (they can't digest wood, really, AFAIK. They just burrow in it). It is much easier to find wasps that gnaw on wood than carpenter bees that do this. The reason, I am guessing, is that the carpenter bees have no interest in openly advertising the location of their largely defenseless larvae and of the food supply, whereas wasps gnaw on wood to build their nests elsewhere. --Dr Dima (talk) 01:58, 14 July 2010 (UTC)[reply]
it is mating season for bees but i thought the drones cant fly. and i dont know why they dont go to the flowers we have in abundance in our garden instead of dying--98.221.179.18 (talk) 10:57, 14 July 2010 (UTC)[reply]
Of course drones can fly. That's pretty much the whole evolutionary point of having them :) . In most social bees the drones are basically flying insemination devices. Carpenter bees are not really social, so drones also protect the tunnels, at least in some species. --Dr Dima (talk) 11:17, 14 July 2010 (UTC)[reply]
Huge bees with shiny abdomens could be the Eastern cicada killer, which are actually wasps, not bees, but they have a more bee-like shape than a wasp-like shape. Carpenter bees are of similar size to a bumblebee, while cicada killers can be shockingly huge. The "three times the size of a bumblebee" indicates that the OP may be noticing a cicada killer instead of a Carpenter bee. --Jayron3222:43, 14 July 2010 (UTC)[reply]
Possible, but I'd be very surprised. Cicada-killers look like hornets, not like bumblebees at all; and they nest in the ground, not in wood. A picture would be the best, of course, even a low-res one. --Dr Dima (talk) 02:43, 15 July 2010 (UTC)[reply]
The simplest ink you can make would be from 'lamp black' - the fine-grained carbon that's deposited onto a surface from a smokey candle or some other kind of yellow-burning flame - mixed with a small amount of either water or alcohol (alcohol would help it dry faster on the page). Since you're going 'retro' here, you'll presumably be writing by the light of a tallow candle or an oil lamp...so this stuff will be easy to find! The mixture would probably be ground together in a pestle and mortar to ensure that the result is a smooth liquid. This stuff is bad for your lungs - and you should probably wear a face-mask while you're collecting the dry ingredient (although it should be safe once you've mixed in some liquid to stop the dust flying into the air). I wouldn't make a large batch of the stuff (at least not to start with) because it will settle out from the liquid and have to be re-ground when you need it again. This kind of ink is inconvenient, and doesn't produce great results...but that's why we now have ballpoint pens! SteveBaker (talk) 13:05, 14 July 2010 (UTC)[reply]
"One great beauty of lampblack, especially for ink-making, is that it is extremely fine in grain, and does not need to be made finer by grinding. It may be used just as it is found deposited on the cold surface of metal or earthenware, and needs only to be mixed with a little gum water to make a black ink corresponding to what we call India ink." -- The Materials and Techniques of Medieval Painting, Daniel V. Thompson, Dover Books. You'll need to stir it again before using it, is all. Gum arabic is commonly found in art shops next to the watercolours, by the way. 213.122.25.117 (talk) 14:06, 14 July 2010 (UTC)[reply]
Then there must be some kind of subtelty about how the carbon is deposited. I did this (many years ago) with the soot from a candle made from a dried grass 'wick' and animal fat - condensing out onto a large, smooth river-rock, scraping it off with a slice of flint and mixing it with rainwater (yes, it was one of those "back to nature - how well can you survive with no tools or modern conveniences" kind of things). As I recall, the stuff I wound up with was maybe about the grain size of table-salt. It clearly wasn't going to be useful as ink - so I ground it up (more rocks!) - and then it worked reasonably OK so long as you didn't try to use it on really shiney paper (it wrote OK on dried leaves though...so that was OK). Maybe it matters what the smoke condenses onto - or perhaps for some reason the nature of the fuel you're burning matters? Anyway - this works. You can do it fairly easily and a crude quill pen works just great with it. SteveBaker (talk) 19:30, 15 July 2010 (UTC)[reply]
Yes, the book does say that the source of the flame makes some difference, because "there is apt to be a certain amount of unburnt or partly burnt material ... which may affect both the colour and the working properties of the pigment". I can't see how animal fat is different from tallow, though (both beeswax and tallow are suggested, those being what candles were made of)... well, I suppose tallow is purified, so there you are, unpurified fat makes lumpy ink, perhaps. Beeswax is likely better. (And where are you going to find a tallow candle anyway?) 213.122.43.197 (talk) 01:53, 16 July 2010 (UTC)[reply]
Resistor calculation
I would like to power some LEDs while stationary on my bike and here is part of a circuit that I hope might work. I'm trying to calculate what resistor, if any, is needed between the battery and the LEDs. I don't know yet, whether I want it before or after the transistor.
My LED's have a max rated forward voltage of 3.8 V (and normal forward voltage of 3.3 V) and each needs 20 mA (I'm not certain whether I want eight LEDs or even more, but assuming it's eight, that's 160 mA total) and I need to use a PNP transistor but I don't know which one; is there a difference? I read somewhere that 0.7 V is a typical loss over a t
ransistor? My battery is 4.8 V, consisting of 4 NiCd cells.
The circuit you show won't work because the pnp transistor needs a current flowing between its base and the negative rail. Frankly, I don't see the need for a transistor there at all; you're turning on and off with a SPST switch. You're right that you can treat the LEDs as being in parallel, but you run the risk of uneven lighting because you can't guarantee that their characteristics are matched when the same voltage is across them, Some may be brighter or dimmer than others. If each of the eight LEDS actually does drop 3.3 V at 20 mA, and your battery actually is 4.8 V, then a single resistor of (4.8 − 3.3) / 0.16 = 9.35 (use 9.1 or 10) ohms would do the trick - you'd be dissipating 1.5 x 0.16 = 0.24 watts in it (a bit close to the maximum rating for some small resistors). Personally, if space wasn't a problem, I'd use one 75 ohm resistor in series with each LED. That would likely lead to more uniform brightness if the LEDs weren't perfectly matched and reduce the dissipation in each resistor to a negligible wattage. --RexxS (talk) 02:12, 14 July 2010 (UTC)[reply]
Even the diode D5 is not needed. Remove the transistor and the diode D5, reverse the polarity of the batteries such that the positive terminal connects to the anode and the negative terminal connects to the cathode. See the article LED if you need details. The article says that a typical voltage drop is about 2V for a red LED. In this case, you can even put two LEDs and a suitable resistor in series and use four such combinations in parallel. This will bring down the current. -- WikiCheng | Talk05:12, 14 July 2010 (UTC)[reply]
Refer to the circuit diagram shown Resistor calculations. With this, assuming the voltage across each LED is 2V, the voltage across each resistor would be 4.8 - 2 * 2 = 0.8. If you need a current of 20 mA (0.02 A), then you will need to use the resistor of value 0.8 / 0.02 = 40 ohms. It will consume about 0.8 * 0.02 = 0.016 W and hence a 47 ohm quarter watt resistor would do.
If you use a single LED instead of two, then the calculations would change. The current through each resistor will increase and hence you may need a resistor of higher wattage. WikiCheng | Talk10:47, 14 July 2010 (UTC)[reply]
Here is the full circuit. I corrected the batteries (thanks!!) but the D5 diode and the T1 transistor are needed. The idea behind the SPST switch is that I can switch off the circuit when the bike is parked/locked up, so I don't drain the batteries. When on the road, I want the transistor to switch on the LEDs when I stop at lights. Does the transistor work, now that the orientation of the batteries has changed (just a careless mistake)?
The LEDs which I'm looking at buying (taking into account their brightness) have a forward voltage of 3.3 V but can tolerate a max of 3.8. I don't want to use a resistor to bring the voltage down to 3.3 V because the LEDs will quickly loose full brightness as the batteries drain. This way, each battery has to loose 0.15 V (=at least a few minutes?) before the brightness starts to decrease. 89.243.130.113 (talk) 10:56, 14 July 2010 (UTC)[reply]
Ok, so what you want to do is monitor the voltage across the two series LEDs 'XPG' and switch on the other LEDs when it drops below a certain voltage? The thing you have to realise is that semiconductor junctions have an approximately exponential relationship between voltage and current, so you cannot simply apply a voltage to them and expect to be able to predict the current. You always need a current limiting mechanism (usually a resistor), particularly as the junctions have a negative temperature coefficient of voltage - which means as they get hotter, they pass more current and get even hotter. You will always need some series resistance. Looking at your full diagram, when the alternator is stopped, you are clamping the battery with the E-B junction of the transistor and the two 'XPG' junctions. There's no limit to the current, so you will need a resistor in series with the base of the transistor. That will have to be calculated from a knowledge of the forward drop of the LEDs marked 'XPG' and the fact that to turn on the transistor fully, you should plan to have a B-E current of 16 mA, about one-tenth of the C-E current (160 mA). Then you still need to limit the current through your LEDs 1–8 to 20 mA each. A fully saturated power transistor can drop as little as 0.2 V (look for VCEsat in the data sheet). That would give a voltage of about 4.6 V at the collector, so the resistor(s) have to now drop about 1.3 V while passing the current (160 mA for one or 20 mA for eight individual ones). That gives a single resistor of 8.2 ohms or eight individual series resistors of 63 ohms. I'd prefer the latter, to allow for individual variations in the LEDs 1–8. I suspect you're also trying to use the transistor to provide a constant current as the battery voltage reduces, but you really don't have enough voltage headroom to do that with simple circuitry, although FET-based ICs that provide constant current are available with relatively low voltage drops, but that would make it a lot more complex and expensive. However, you are using NiCd batteries which have a low internal resistance and a remarkably small voltage drop as they discharge, so that would compensate to some extent for your fears of the light dimming as the batteries discharge. Finally, I should warn that you're clamping the LEDs 'XPG' to about 0.7 V above the charging voltage of the batteries – please ensure this will give the results you want, or again use a resistor in series with diode D5 to limit the charging current to the NiCds if the voltage across the 'XPG' LEDs should be more than that when the alternator is running. --RexxS (talk) 14:20, 14 July 2010 (UTC)[reply]
This is my modified circuit but I'm pretty confused. My understanding is that when the bike is in motion, the 6 V will charge the batteries (1.4 V are needed to fully charge each NiCd cell so if I put a resistor there, I prevent them from fully charging and reaching 4.8 V?) I don't know how to figure what current will pass through the batteries relative to the LEDs.
When stationary, the potential difference that normally exists between the emitter and the base reverses from <-0.7 to +4.8 and current flows through the emitter to the base and collector but to return to the batteries from the base, it must pass through the XP-G LEDs which have a forward voltage of 3.0 V and therefore wont allow a current to pass? How will any current be able to pass through the base? Surely the LEDs themselves offer plenty of resistance to only 4.8V? --SeansPotato Business20:07, 14 July 2010 (UTC)[reply]
Now that we know the voltage drop across the 'XPG' LEDs (around 6 V) when conducting, we can do a little more working out. You can see that the return path for current from the base of the transistor in your new circuit has to pass through the XPG LEDs. But you should be reckoning on around 16 mA for the base current and the base of the transistor needs to be at about 4.1 V (battery voltage &minus 0.7) for it to conduct. With the diodes requiring about 6 V to conduct, you don't have enough voltage to sink 16 mA through them, so the transistor won't switch on - that is, the LEDs will offer a huge resistance to 4.8 V as you say. Here comes the next problem: you could put a resistor across the two diodes to provide a return path, but a low value resistor would waste energy when the alternator was working. The other problem is that there is C3 which has to discharge below 4.1 V for the transistor to switch on, but once the XPG diodes have switched off, it has no effective discharge path other than leakage. If C3 really is 3.3 farads (please check), a super-capacitor, then the discharge time constant for even a 100 ohm resistor is 330 seconds (and 100 ohms would waste 60 mA when peddling). I doubt you want to wait five minutes at the lights for the transistor to switch on. Have another look at C3 and see if it's actually a smaller value that we could discharge within sensible times.
R11 will limit the charging current into your NiCds - you have to drop around 0.5–1.1 V across it when the XPG LEDs are on (using Vf=3.0–3.3 V as indicated). The additional current you are asking the alternator to supply ought really to be a 'trickle' current, as NiCds don't like continuous charging above a certain value, usually rated around "N/10" – that means for example a 1200 mAH NiCd will tolerate up to 120 mA continuous charging - for such batteries, R11 would be 9.1 ohms (6.6 &minus 4.8 &minus 0.7)/0.120.
R10 will be calculated to give a base current sufficient to saturate the transistor when it is supplying 160 mA collector current, but we need to know what value of discharge resistor for C3 will be used for us to work that out. It's worth noting that a normal transistor will usually guarantee saturation if IB is one tenth of IC, but a high-gain/darlington power transistor would allow much smaller base currents, while a power FET would need virtually no current, but would require other design considerations. --RexxS (talk) 00:01, 15 July 2010 (UTC)[reply]
The capacitor was a mistake! I got the units wrong! I was 3.3mF! Now it's 4.7mF, 'cause I found a better value option.
What if I just added another cell to the battery? Then current could flow through the LEDs (I estimate 50mA at 2.6V each - the graph is at the top of page 4 on this datasheet) - it ends before it touches either axis. With the extra cell in the battery, I wouldn't need a resistor to limit current during charging, although I will never get them fully charged.
Here is my circuit now. The capacitor can discharge through the LEDs to below 5.4V, during which time, the battery-powered lights take over. With 5.4V over the XP-Gs, the 12 ohm resistor limits the current to 50mA, with 0.6V across it. What do you think?
Also, one thing stands in the way of my full comprehension of the circuit and I've highlighted it in yellow. It's taken from circuit 6 on this page, where it's described as "increasing power at moderate speeds". I've asked elsewhere and one person said they think it smooths out the fluctuations while another said it was a voltage doubler. I think the capacitors are too small to smooth. --SeansPotato Business21:16, 15 July 2010 (UTC)[reply]
Ideas for scientific imagery
I am considering some post grad studies, specifically a new course offered at a local art university entitled "Visualizing Science and Art". To be accepted by the institute, a portfolio and an admission test is required.
I possess adequate (?) skills in computing and graphics, but am widely illiterate in scientific disciplines beyond the level of secondary education. Fortunately, some tests indicate that, given time, dedication and curiosity, one can learn new tricks in advanced canine years.
So, the question: Can you suggest some (maybe six to eight) "smallish" projects for this portfolio, preferably from different disciplines, where I could test my skills, both at researching and visualising scientific ideas?
Of course, images / short movies will be made available to the WP and can be linked to relevant articles if expert editors deem them to be constructive didactic tools. Feel free to post to my talk-page, if required.
Thank you. --Cookatoo.ergo.ZooM (talk) 09:01, 14 July 2010 (UTC)[reply]
Go to American Scientist and look through their current and past issues, paying special attention to the column called "Sightings". It's devoted to scientific visualizations, and many of the articles and images are online. If you know how to use Google to find what you want, do a site search for "sightings" and/or "visualizations". There is enough material there to keep you busy for years. Good luck. Viriditas (talk) 12:29, 14 July 2010 (UTC)[reply]
The obvious one to me would be wildlife photography. Sow about finding a species article on here that can be found where you live but is currently very short and lacks images and trying to improve it? You could also look at some microscopic stuff - try looking at this site for some ideas. There are also some cool books filled with scientific pictures of varying scales - similar to the power of ten video. I can't remember what they are called but maybe someone else can. Smartse (talk) 14:34, 14 July 2010 (UTC)[reply]
I guess the question we should ask you is, what type of scientific visualization are you hoping to generate? Is it photographs and photo-like images (microscope images, computed tomography, astrophotography, etc.)? Is it quantitative information (for numerical data presented effectively and honestly, see Edward Tufte's gold-standard works, especially The Visual Display of Quantitative Information)? Is it processes, project outlines, or flowcharts? Is it diagrams or explanatory illustrations? Is your target audience scientific specialists, university students, the general public, or high schoolers? Do you have some examples of what type of work you're considering? Finally, what access do you have to original data/material which might guide your chioces? TenOfAllTrades(talk) 18:25, 14 July 2010 (UTC)[reply]
Without knowing your skills, it's hard to know what's possible. In my opinion working to make clear graphics that explain complicated things—like, say, quantum mechanics—would probably be a fairly good project and be impressive to anyone reading them, and there are plenty of existing models to look at, think about, copy, improve upon, etc. E.g. imagine you are illustrating an article in Scientific American which discusses: quantum leap, uncertainty principle, double-slit experiment, EPR paradox, Bell's inequality, and Wheeler's delayed choice experiment. Try to come up with images that both look better and explain better—at a glance—than do the ones in Wikipedia articles. (Which frankly won't be very hard!)
That's one approach. The other is to take a look at the work of Edward Tufte, which is basically the Alpha and the Omega for thinking clever thoughts about visualizing data. I see TenOfAllTrades had this same idea... if you haven't seen Tufte's work, give it a glance. --Mr.98 (talk) 23:09, 14 July 2010 (UTC)[reply]
Am I the only person who doesn't like Edward Tufte? I mean, at all? I think his diagrams are hideous and do at best an average job of communicating information. Designing effective diagrams is not all that difficult, and the world is full of people who do it better than Tufte. I can't be the only person who feels this way. -- BenRG (talk) 07:55, 15 July 2010 (UTC)[reply]
I think his diagrams are generally fine, but more important is his overall methodological approach. I think it's hard to argue with his general arguments—diagrams should be clear, devoid of chartjunk, should take care not to unintentionally mislead, and should be rich in interpretation (and he gives lots of examples pro and con of each)—whether one likes his own aesthetic implementations of them. In a world where most popular forms of representation of quantitative data are limited to the horrors of Microsoft Excel, I think he does a lot of good... --Mr.98 (talk) 12:28, 15 July 2010 (UTC)[reply]
Phone connectors in the UK
I know that phones in the UK have a different type connectors than those in the US, but form factors aside, are the two interfaces electrically compatible? Also, do the phones in the UK have different handset connectors than those in the US? Will a headset amplifier made for US phones work with a UK phone, assuming no connector issues? —Preceding unsigned comment added by 173.49.10.26 (talk) 11:14, 14 July 2010 (UTC)[reply]
Yes they are electrically compatible - you can buy simple mechanical adapters between the two. As for headset amplifiers it should work, but I'm not sure if there's even a standard on the headset connector for phones. --antilivedT | C | G02:05, 15 July 2010 (UTC)[reply]
While Antilived's comment is mostly accurate, bear in mind BT jacks used in NZ and from reading the article in the UK very occasionally have a third wire used for the ringer. I'm not sure if there is a standard way for this on RJ11, or if it was even used (there article isn't that clear). Nowadays since all phones have their own ringers, and most houses have moved to 2 wire configs (which is the current standard) but in the unlikely event you have a very old phone which doesn't have a ringer it may not work with an adapter (of course it also won't work with the vast majority of NZ sockets and I'm guessing UK sockets by far). I think this is only one way so plugging a phone with a ringer even if it has an RJ11 plug into a 3 wire BT socket with appropriate adapter should be fine. Nil Einne (talk) 13:52, 15 July 2010 (UTC)[reply]
Exoplanetary systems in Sagittarius
How many stars in Sagittarius are known to have planets? (The Wikipedia article says 16 and 19, so that needs to be fixed) Also, where can I find a list of these particular stars? Finally, is it true that "Sagittarius has more planetary host stars than any other constellation"? Viriditas (talk) 12:10, 14 July 2010 (UTC)[reply]
1. regarding 16 vs 19. "Number of stars known to have planets" is a (usually increasing) function of time, so it simply needs a date and a reference. 2. Regarding "more planetary hosts". Sagittarius is a constellation, that is, a group of stars that look close for the Earth-based observer but are not necessarily close to each-other (indeed, distance from Earth to different stars in the same constellation is often very different). The farther is the star from Earth, the harder it is to detect a planet orbiting it. Besides, we do not even know how many stars there are in the Sagittarius. This being said, it is indeed possible that Sagittarius houses more Milky Way stars (and therefore maybe more stars with planets) than any other constellation. That is because the center of the Milky Way galaxy (our galaxy) happens for the Earth-based observer to lie within the bounds of Sagittarius constellation. Does this help? --Dr Dima (talk) 21:31, 14 July 2010 (UTC)[reply]
Lately, more and more of my friends have been buying head massagers (like the ones seen here: http://www.rolostore.com/images/medium/kk_headm.jpg). I've noticed that these things have interesting, differing and sometimes hilarious effects on people. For instance a friend of mine is immune to the effects, another finds them overly tickelish and yet another just becomes totally relaxed. I myself get goosebumps. What could explain the effect of these simple devices? —Preceding unsigned comment added by 137.224.252.10 (talk) 12:13, 14 July 2010 (UTC)[reply]
They obviously don't have any meaningful effect but reflect the expectation of the purchaser. Different strokes for different folks, but they all pay. 86.4.183.90 (talk) 13:28, 14 July 2010 (UTC)[reply]
Not a good answer in my opinion, 86.4. People have varying degrees of sensitivity to stimulation. Complete OR, but I had no expectations when one of those devices was used on me, and the experience was quite noticeable. 10draftsdeep (talk) 20:03, 14 July 2010 (UTC)[reply]
Methyl 1 d - muscle growth drug
This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. TenOfAllTrades(talk) 13:30, 14 July 2010 (UTC)[reply]
whenever I eat watermellon I am struck by the fact that it resembles flesh somewhat. has anyone tried implanting it to see what happens? what does the body have to say about it? —Preceding unsigned comment added by 92.224.207.86 (talk) 13:26, 14 July 2010 (UTC)[reply]
(EC) Doctors don't randomly implant tissues into people to see what would happen. That would be very, very unethical and most likely, illegal. In any case, as watermelon flesh is 92% water, and most of the rest seems to be sugar, it would be very surprising indeed if the human body was able to use watermelon flesh for anything (other then eating it). Googlemeister (talk) 14:24, 14 July 2010 (UTC)[reply]
whenever I eat jelly I am struck by the fact that it resembles vitreous humour somewhat. has anyone tried gouging out someones eyes and replacing it with jelly to see what happens? —Preceding unsigned comment added by 92.19.107.38 (talk) 15:04, 14 July 2010 (UTC)[reply]
Whenever I eat human flesh, I am struck by the fact that it resembles watermelon. Has anyone tried grafting arms and legs onto a watermelon to see what happens? 213.122.25.117 (talk) 15:14, 14 July 2010 (UTC)[reply]
As a serious response to what seems to have been a serious question, watermelon will likely cause a foreign body reaction that would initiate a granuloma. Because watermelon is very soft and easily compressible, it would not fit into the category of space-maintaining graft material, such as calcium sulfate, silicon dioxide or allograft/xenograft bone particles such as would be used in a bone graft. In fact, calcium sulfate is not very firm and resorbs quite quickly (few weeks) and so is also not good if one would like to maintain space. Everything I've said above applied primarily to intraoral grafting and can be found in any advanced-level dentistry text. DRosenbach(Talk | Contribs)15:18, 14 July 2010 (UTC)[reply]
I notice that the skin on the backs of my arms (where the triceps are) is noticeably colder than other places on my body. Why is that? It doesn't matter if I have had a workout and my metabolism is elevated, or if I am otherwise fairly warm, the backs of the arms always feel cool. Hemoroid Agastordoff (talk) 16:36, 14 July 2010 (UTC)[reply]
why are baby birds less scared of humans than the adult birds????? there is a mockingbird and it has about three babies hidden around our yard. the adults fly away at first sight of humans, but the babies even let us pick them up. some people say the parents teach the baby birds to be scared --98.221.179.18 (talk) 17:42, 14 July 2010 (UTC)[reply]
1. You're not supposed to pick up baby birds. The parents may abandon them because they will smell different after coming into contact with your skin. 2. Our fear article is about humans, but it notes that although a capacity to fear seems to be part of human nature, "people develop specific fears as a result of learning". Human babies fear nothing, either; it's through learning that they develop fear. Comet Tuttle (talk) 18:07, 14 July 2010 (UTC)[reply]
Moving them is a problem. Just touching them is usually ok. I still wouldn't advise doing it without a good reason - you may interfere with the bird's usual development even if it isn't abandoned. The adult won't feed it while you are holding it, for instance, so it may not get as much food as it would otherwise get. --Tango (talk) 20:59, 14 July 2010 (UTC)[reply]
thats what it did around my house. the baby called an alarm because a cat was near and the mother attacked the cat, pecking its head and tail--Horseluv10 (talk) 21:36, 14 July 2010 (UTC)[reply]
I don't know whether baby birds feel fear or not - but just because they don't have a use for the emotion (yet), doesn't mean that they don't feel it. Evolution is a harsh mistress. If fear-when-young doesn't actually worsen their chances of survival then they might very well develop the fear response very early on just because it's an 'easier' way for the mechanism to form in the growing brain. Emotions such as fear, stress, anger and pain are often horribly counter-productive - but so long as (on average) they help more often than they hinder - those emotions will be there. What benefit is there for a zebra to feel horrible pain as its living body is ripped to shreds by a lion? Zero - but having that terminal pain doesn't in any way decrease their ability to pass on their genes because death is the next thing to happen. There is no drive whatever for a zebra to evolve the ability to die peacefully under those circumstances - so the pain is there regardless. Nature is horrifyingly cruel. SteveBaker (talk) 22:51, 14 July 2010 (UTC)[reply]
The suffix "-osis" just means "condition", but usually a diseased condition of some kind.
"-itis" means "inflammation", which is just one kind of pathological condition.
"Dissecans" means "dissected" or "split".
So putting all that together:
"Osteochondrosis" is any disease of the bone and cartilage.
"Osteochondritis" is when the bone and/or cartilage are inflamed, and kind of osteochondrosis.
"Osteochondritis dissecans" is a condition of the bone and cartilage where there is inflammation and where the bone and/or cartilage has split. It is a kind of osteochondritis, and therefore also a kind of osteochondrosis.
Medical terminology does not always match the things described, as many usages evolve past their roots, but reading osteochondritis dissecans indicates that the above is correct: "[[Osteochondritis dissecans]] is a type of osteochondrosis in which a lesion has formed within the cartilage layer itself, giving rise to secondary inflammation.". --Sean19:09, 14 July 2010 (UTC)[reply]
I'm not sure. People are only fed by IV if their digestive system is not working (people that are just in a coma are fed by a tube into the stomach, rather than into a vein), so it may depend on what is wrong with their digestive system. You can't get stomach contractions if the muscles around the stomach don't work, for example. --Tango (talk) 20:56, 14 July 2010 (UTC)[reply]
Yes. Intravenous hookups supplies only ion-balanced fluid but no nutrients. People who are, for instance, in a coma, are also provided with a gastrointestinal tube through which they are fed a mush of necessary nutrients (protein, carbohydrate, etc.) DRosenbach(Talk | Contribs)22:32, 14 July 2010 (UTC)[reply]
Short answer (from reading around a bit) is that I think they feel hunger for at least the first few days - but that feeling then subsides. However I have only indirect evidence of that:
Hunger_(motivational_state)#Biological_mechanisms says that "The fluctuation of leptin and ghrelin hormone levels results in the motivation of an organism to consume food. When an organism eats, adipocytes trigger the release of leptin into the body. Increasing levels of leptin results in a reduction of one's motivation to eat. After hours of non-consumption, leptin levels drop significantly. These low levels of leptin cause the release of secondary hormone, ghrelin, which in turn reinitiates the feeling of hunger." - which suggests that so long as those hormones are kept at the correct level, you won't get hungry.
Our Leptin article says that "Leptin has also been discovered to be synthesised from gastric chief cells and P/D1 cells in the stomach." - so it seems likely that without the stomach being stimulated in appropriate ways, you'd not have much leptin - and you'd be hungry no matter how well your intravenous feeding works. It also explains that administering leptin by injection doesn't work well at supressing hunger - for all sorts of complicated reasons.
Our Ghrelin article says similar things: "Ghrelin is a hormone produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger." - so, again, if there is no stomach stimulation, you'll feel hungry.
Hunger_(motivational_state)#Hunger_pangs also says that hunger pangs disappear after 3 to 4 days without food...so there is clearly something more complex going on.
Tentative conclusion: You'll be OK for the first 12 to 24 hours - then you'll feel starving hungry for a few days - then you'll be OK again.
That is incorrect, there are people who live their entire life on IV nutrition. Intestinal cancer for example, and certain birth defects. Ariel. (talk) 06:21, 15 July 2010 (UTC)[reply]
The article? Total parenteral nutrition: "Long-term PN is occasionally used to treat people suffering the extended consequences of an accident, surgery, or digestive disorder. PN has extended the life of children born with nonexistent or severely deformed organs. People have survived on total parenteral nutrition for more than 35 years, living fully productive lives." Ariel. (talk) 10:10, 15 July 2010 (UTC)[reply]
My two bits. I was once (three years ago) hooked up to an IV for about 24 hours. Normally I eat quite a lot (though a good metabolism doesn't let this be seen)), but when I was fed through the tube, I did not feel hunger, which was very, very weird. It was more like missing tastes of things (I was forbidden to eat because it was duodenal ulcer treatment). --Ouro (blah blah) 21:26, 15 July 2010 (UTC)[reply]
I have been told personally ( first hand info) from several of my patients in the ICU ( who have been on total parenteral nutrition) that they were very hungry, one particular patient was on life support for 68 days and he used to tell me specifically ( by writing on paper) that he wanted coffee and that he craved for home cooked food. he specifically told me he was hungry- ravenously!!! Fragrantforever 07:55, 17 July 2010 (UTC)
Your brain would explode. Well, not really, but a field strong enough to do that would cause massive epileptic seizures, probably paralyze the lungs, and very likely cause the heart to go into fibrillation. Looie496 (talk) 02:57, 15 July 2010 (UTC)[reply]
Says who? Neither the frog nor the cricket "exploded" when levitated [12]. They both remained active while levitating, and while there is no way to know the internal quality of their experience, neither seemed harmed after wards. Keep in mind that it is a static field (albeit a spatially varying one), so there isn't a large electrical component which seems to be what you are basing your response on. Also, the field strength in the levitation example is only about 12 times larger than is routinely used in magnetic resonance imaging with no substantial ill effects. There probably would be some strange sensations, but it is not obvious to me that it would be fatal or even dangerous to humans. (Though anyone wanting to try it should certainly run many safety tests first.) Dragons flight (talk) 03:56, 15 July 2010 (UTC)[reply]
I do not think one would "explode" or have any substantial ill effects, maybe if you were to move in the magnetic field. Magnetic levitation of water on earth (approx. humans) needs a gradient in the magnetic field of 1400 T^2/m, since a lying human is at least 25 cm high levitation of a human needs at least 19 T while levitation of a frog that moves in any direction and is 2 cm needs at least 5 T. even stronger field are probably needed in order to get stability and uniform levitation in all parts of the body. A lying human will probably need 50 T and a standing human will need 150 T. This is far stronger than the strogest magnets on earth. —Preceding unsigned comment added by Gr8xoz (talk • contribs) 05:22, 15 July 2010 (UTC)[reply]
It would feel like free fall (like in the space station), free fall is commonly (but incorrectly) referred to as no gravity. Note: Free fall (and no gravity) does not feel like floating, it feels like falling. It takes a while to get used to that. It does not feel like floating in water. Ariel. (talk) 06:19, 15 July 2010 (UTC)[reply]
I'm skeptical that it would feel like free fall -- specifically, you're not falling. You're stationary in a grav field, just as you are when you're standing on the ground, only you're not standing on the ground. Gravitational effects should be unchanged. A skydiving simulator (with the giant fans in the floor) would be the easier-to-access analogue; has anybody played with one? — Lomn11:50, 15 July 2010 (UTC)[reply]
I agree with Ariel. As far as the magnetic force per kg is uniformly equal and opposite to gravity, it is like free fall, unlike a force of wind acting on the surface.--Patrick (talk) 13:26, 15 July 2010 (UTC)[reply]
It would feel like free fall, because the forces that act on your body do so without causing much deformation; they act approximately uniformly per unit mass. The reason why standing on the ground does not feel like being in free fall is because the normal force only acts on the boundary of the ground and your body. This force only causes the atoms that touch the ground not to accelerate through the floor. But the next layer of atoms in your feet also don't accelerate, and this is due to the fact that they move a bit closer to the atoms on the boundary and then experience a force exerted by the atoms on the boundary. So, the normal force is transferred to the whole body via deformations. You can feel the internal stresses that this causes. Count Iblis (talk) 14:36, 15 July 2010 (UTC)[reply]
It should be noted that free fall (as used in this context) is not the same situation as one might experience in (for example) those skydiving simulators with the giant fans. (It's rather an awkward problem of terminology — physicists tend to talk about free fall as meaning a situation where a body is not significantly affected by drag, whereas skydivers use it to mean all the time before they deploy their parachutes.) In a skydiving simulator, one is experiencing the equivalent of a fall through air at terminal velocity, where the gravitational force on your body (indeed, on all of the infinitesimal parts of your body) is evenly matched by the drag force applied to your lower surface by the upward blowing air. As Count Iblis describes above, in the skydiving simulation the forces are actually quite similar to what you would experience lying on the ground. Force is applied to whatever part of you is 'down', and then conveyed through the body. It's not 'free fall' in the physicist's sense, because each part of your body can tell that force is being applied from its underside to lift it, and in turn applies upward force to support the parts above. When at terminal velocity while skydiving, your body can readily sense which direction is 'down', by much the same mechanisms by which you know which way is 'down' when you're lying in bed.
In contrast, the diamagnetic levitation effect acts on the entire body, fairly evenly. (At least, this is my understanding.) Instead of applying a countergravitational force to the bottom surface of the levitated body, it provides a small, uniform lift to every bit of mass throughout. Bits of matter on the 'bottom' don't have to support the weight of bits of matter on the 'top' — and that makes a huge difference to the sensations of the individual being so levitated. It's really a free fall as far as the body is concerned. (Actually, I've cheated a bit in my definitions here, too. Usually 'free fall' for physicists means that a body is only being acted on by gravitational force. In a sense, what we're doing here is applying a bit of 'antigravity' through electromagnetic means to null out the effects of gravity. What an object experiences here is probably functionally close to real zero gravity — locally flat spacetime, with no gravitational force acting.) TenOfAllTrades(talk) 15:06, 15 July 2010 (UTC)[reply]
And now I'm going to respond to myself, and note that the perception of weightlessness or freefall is going to be even more complicated than we'd like in this situation, because the diamagnetic levitation effect is going to affect different materials slightly differently. The magnetic permeability of bone is going to differ from that of soft tissue, for instance, which means that the amount of levitation force felt by each type of tissue will also be slightly different. What effect this will have on the perceptions experienced by the vestibular system I couldn't guess. TenOfAllTrades(talk) 20:14, 15 July 2010 (UTC)[reply]
The strongest magnetic field that you are ever likely to encounter personally is about 10^4 Gauss if you have Magnetic Resonance Imaging (MRI) scan for medical diagnosis. Such fields pose no threat to your health, hardly affecting the atoms in your body. Fields in excess of 10^9 Gauss, however, would be instantly lethal. Such fields strongly distort atoms, compressing atomic electron clouds into cigar shapes, with the long axis aligned with the field, thus rendering the chemistry of life impossible. A magnetar within 1000 kilometers would thus kill you via pure static magnetism -- if it didn't already get you with X-rays, gamma rays, high energy particles, extreme gravity, bursts and flares...
MRIS give me headaches though. I don't know whether it was the placebo effect but I actually believed there were induced currents and depolarisations running through my brain. John Riemann Soong (talk) 15:03, 15 July 2010 (UTC)[reply]
I don't think it's a placebo effect, it's well documented that many individuals feel "weird" a bit while around the large MRI devices. I personally feel a bit nauseated and dizzy when I have to stick my head in the bore. -- Sjschen (talk) 21:19, 15 July 2010 (UTC)[reply]
On safety, it's worth noting that clinical MRI instruments now regularly reach fields of up to about 7 tesla ([13]), and there are some small-bore instruments (for wrists and knees and such, rather than the whole body) which have fields up to 9.4 tesla or more. There has been some fairly extensive testing on the effects of these high fields on the human body. You can start here or here and work back through their references. Meanwhile, the levitating frog demo was done at a field of 16 tesla. In other words, we're actually not that far from exposing humans to sufficiently high field strengths for this sort of levitation — though generating a full-human-sized 16 T field represents a non-trivial engineering challenge. TenOfAllTrades(talk) 15:17, 15 July 2010 (UTC)[reply]
I'll be looking at the literature, but can anyone suggest to me a safe threshold for electric fields to induce excitement in cells (especially constitutive exocytosis). Preferably protocols that minimises any membrane depolarisation, and definitely minimises the risk of apoptosis and mass cell death. I want to stimulate the cells, not stress them.
I'm trying to track nanoparticles for several hours within *live* cells being observed under a (very expensive) microscope for several hours. What voltages and currents should I use? We do have batteries and various apparatuses (but we normally use them in vitro rather than to induce anything in vivo). I am working with lung cancer epithelial cells, not nervous or neuroendocrine cells. John Riemann Soong (talk) 03:36, 15 July 2010 (UTC)[reply]
Membrane depolarization is the signal that transmutes an electric field into a cellular response, so asking for excitement without depolarization is a contradiction. In any case, generally tissue destructive effects are determined more directly by current than by voltage, and more by how long a current is sustained than by how strong the current is. Figuring out how strong a field you are creating with a given stimulus protocol is likely to be very difficult. If you want to apply electric fields, I advise getting hold of a device called a "stimulus isolator", if you don't already have one. They are standard equipment in electrophysiology labs. Looie496 (talk) 23:47, 15 July 2010 (UTC)[reply]
Recently I discovered a yellow glass marble in the street and brought it home, and noticed that it glows a bright yellow-orange under blacklight. I also noticed that a red glass paperweight was glowing yellow as well, but only around the edges (where it appears yellow in ordinary light). What causes these glass items to glow this way? 68.123.238.146 (talk) 03:58, 15 July 2010 (UTC)[reply]
And just in case you're worried - these objects are not especially radioactive. We're not talking about the isotopes of uranium that produce the most radiation - and anything they do produce will mostly be absorbed by the surrounding glass. What is interesting is that uranium glass hasn't been made in any quantity for 60 or more years - so these objects could be rather old. SteveBaker (talk) 12:33, 15 July 2010 (UTC)[reply]
Backing up a moment, I re-read the OP: he said that it fluoresces "yellow-orange", which isn't a characteristic of uranium glass (it was late, I mis-read). Perhaps I was wrong about this particular marble. Apparently manganese can produce an orange fluorescence [14].Acroterion(talk)15:34, 15 July 2010 (UTC)[reply]
Heisenberg quote on quantum mechanics and Indian philosophy
I have seen in many places the quote "After the conversations about Indian philosophy, some of the ideas of Quantum Physics that had seemed so crazy suddenly made much more sense" attributed to Heisenberg. Wikiquote says it is a comment made by Fritjof Capra about Heisenberg. Did Heisenberg actually share this position ( quantum mechanics and Indian philosophy)? Is it fare to attribute this quote to Heisenberg? 220.227.207.32 (talk) 04:11, 15 July 2010 (UTC)[reply]
About this quote Fritjof said "he (Heisenberg) told me something that I think is not known publicly because he never published it" in an interview (see The Tao of Physics). I could not find any other reference of Heisenberg saying this specific quote but there are several references indicating Indian philosophy had some influence on Heisenberg . - manya (talk) 05:07, 15 July 2010 (UTC)[reply]
One should be very careful about the interpretation of this. People get inspiration from a wide range of sources - but that's not the same thing as saying (for example) that quantum theory is 'based on' Indian philosophy - or that proof of quantum theory somehow validates that philosophy as being true. Inspiration is a complicated thing - often it's just an unrelated topic that provides a mental jolt that unfreezes the brain to look at different approaches to a previously difficult topic. Richard Feynman always said that his interest in bongo playing inspired some of the ideas in his quantum electrodynamics work...he definitely didn't mean that quantum electrodynamics has anything whatever to do with bongo drums or the sounds they make! Analogy is a powerful tool for understanding one topic based on an easier understanding of an unrelated topic...but an analogy isn't a causal or consequential connection between two topics, it's nothing more than some kind of vague structural similarity - and that's an important thing to bear in mind. SteveBaker (talk) 12:30, 15 July 2010 (UTC)[reply]
For that matter, Heisenberg might have been making a joke in the vein of "quantum mechanics makes a lot more sense when I'm drunk" which Capra mistakenly took seriously. -- BenRG (talk) 18:29, 15 July 2010 (UTC)[reply]
Thank you all for the replies. Ignoring these remarks, what was Heisenberg's (own) position on this Capra-type "theory"; that is on the "theory" that quantum mechanics justifies Indian ( which Indian is another question) view of the world. 220.227.207.32 (talk) 04:29, 16 July 2010 (UTC)[reply]
Bearing in mind that Heisenberg died only the year following the publication of Capra's The Tao of Physics, he might not have been very aware of it, or may not have made any recorded pronouncement of any opinion he did have. However, he did give an address in 1973 titled (in translation) "Scientific and Religious Truth", as mentioned in our article on him (last paragraph of the Post 1945 section) which also mentions a couple of books by others that cover his views in this area: these publications, if you can access them, might be of interest to you. 87.81.230.195 (talk) 07:04, 16 July 2010 (UTC)[reply]
TToP was specifically based on the bootstrap model, which was an attempt to understand hadron physics by abandoning the notion of elementary particles. The bootstrap model attracted a lot of interest for a few years, especially at Berkeley, where Capra was at the time, but it was never predictive, and it was abandoned around 1973–5 after asymptotic freedom was discovered and it became clear that the quark model was the correct model of hadrons. So any opinion a physicist might have had about the material in TToP in 1972 would probably need updating by 1976. -- BenRG (talk) 19:43, 16 July 2010 (UTC)[reply]
I happen to know that there will be a very interesting book coming out in the next year or so regarding the Capra book and other similar works that came out in the 1970s and how they were received by the physics community at that time. If you're interested in details I'd be happy to give them to you over e-mail—just use the Wikipedia e-mail function. --Mr.98 (talk) 20:27, 17 July 2010 (UTC)[reply]
whats the best way to kill a tick? yesterday we found 4 ticks around our house and on people. my brother made a contraption that electorcutes them and thats what we do now. we used to burn them with matches. whats your way to get rid of them???--Horseluv10 (talk) 11:31, 15 July 2010 (UTC)[reply]
If they are just wondering around then I would simply crush them with something. If they have latched onto a person or animal then you need to be very careful when removing them. I would suggest purchasing a specialised tick removal tool (basically a piece of plastic with a notch in it that you slide around and under the tick to remove it). It is very important to make sure you remove the whole tick and do not leave the mouthparts in the skin, where they could cause an infection. You should also monitor anyone bitten by a tick for several weeks for signs of Lyme disease. If you have any concerns, I suggest contacting a doctor. --Tango (talk) 11:40, 15 July 2010 (UTC)[reply]
If someone has been bitten by a tick, it is recommended to keep the thing in the freezer in a bag for a few weeks. If the victim in question does show symptoms, the frozen tick can be useful for doctors to analyze later. And if they are fine, there's nothing better than finding a frozen tick in your freezer months later! --Mr.98 (talk) 12:19, 15 July 2010 (UTC)[reply]
talking about crushing them, ticks have VERY hard exoskeletons and that would make them very difficult to crush. we've tried that already with unsuccessful results. but freezing a tick might be a good idea.--Horseluv10 (talk) 12:35, 15 July 2010 (UTC)[reply]
We use an old country remedy: rub some Vaseline all over the little buggers. As they breathe through pores on the side, they will suffocate and fall off. --TammyMoet (talk) 13:28, 15 July 2010 (UTC)[reply]
Listen, and understand. That tick is out there. It can't be bargained with. It can't be reasoned with. It doesn't feel pity, or remorse, or fear. And it absolutely will not stop, ever, until you are dead.
But seriously, all the advice above is good, except that the tick is nothing magical like above - any way to kill it will do the job and won't leave toxins unless possibly if you use some concentrated acid. SamuelRiv (talk) 02:59, 16 July 2010 (UTC)[reply]
On the other hand, there are people who have reported hiccups lasting for years, and that nothing could stop them. ~AH1(TCU)18:43, 16 July 2010 (UTC)[reply]
I have recently finished my High school equivalent studies (A-levels) and am applying for undergraduate medicine in several universities. A local university is offering a Bachelor of Science in Speech Language Therapy (BSc. SLT). I want to know the future potential of such a qualification and the pay grade of Speech Therapists compared to other medical qualifications. Thanks. --119.155.0.198 (talk) 12:26, 15 July 2010 (UTC)[reply]
which, it being illegal to practice without the entirety of that training (with no alternative), artificially limits supply as De Beers does with its diamonds. As for demand, obviously it is almost totally inelastic: I want my finger sewn back on whether it costs $80, $800, $8,000, or, if I can take that much debt on, $80,000. The resulting price is charged in the U.S.; Britain, being "commie bastards" when it comes to health care, do not obey the rules of economics, and you do not have to pay $80,000 (if you could repay that in your lifetime) to get your finger sewn back on. 84.153.255.139 (talk) 16:17, 15 July 2010 (UTC)[reply]
p.s.: if I would pay $80,000, why isn't that the price in the U.S.? (it is in fact less). It is because although I can put aside $80,000 over the next, say, fifteen years, repaying the loan, not everyone could, and so the price is lower. If nearly everyone who needed a finger sewn back on in the United States were a billionaire, with myself being the sole exception, you could rest assured that I would be asked for, say, $13 mil for the operation (if not more). I could not afford that, but the price is not set by me, but by the billionaires, since we're talking about a monopoly situation -- it is illegal for my Uncle Fred to read up on the operation overnight and do it for me for a few hundred. 84.153.255.139 (talk) 16:21, 15 July 2010 (UTC)[reply]
Part of that is because if you let your Uncle Fred do it, at best you would lose your finger anyways, and at worst you would get gangrene, or a nasty infection and die. Googlemeister (talk) 16:49, 15 July 2010 (UTC)[reply]
The US health care system isn't a free market either, though, because of the laws you mention about practising without a license. The US has regulation on one side of the market while the UK has regulation on both. That is why the UK has better healthcare than the US (there are plenty of statistics to back up that claim). --Tango (talk) 16:56, 15 July 2010 (UTC)[reply]
Well, to get that result you have to pick a definition of better and use the statistics that correspond to it. The US has "better" health care in the sense of what you can get immediately if price is no object. At least I would be quite surprised if you have statistics refuting that. --Trovatore (talk) 18:51, 15 July 2010 (UTC)[reply]
The UK has plenty of private health care that you can get immediate access to if you are willing and able to pay (or have insurance). It is no different from the US in that respect. --Tango (talk) 19:17, 15 July 2010 (UTC)[reply]
I know you can get it in the UK (though admittedly I probably wasn't thinking about it; I'm more familiar with Canada, where privately paid health care is essentially unavailable even though not technically illegal). But the question is, is it as good? My understanding is that it is not, at least at the top end. --Trovatore (talk) 21:25, 15 July 2010 (UTC)[reply]
My mother did this track, and hated the dull repetitiveness of therapy. Get a good academic background if you're interested in the subject such that you can always combine research with therapy, or teaching with therapy. SamuelRiv (talk) 03:00, 16 July 2010 (UTC)[reply]
Starting masturbation at a very young age
How do some people learn to do it when they are as young as 5 years old (in my case) while others don't know about it until or after puberty? For me, I wasn't even taught about it but as long as I can remember, I started doing it since I was like 5 years old. I remember getting the exact same sensation of orgasm even though I hadn't ejaculated any semen then (which interestingly suggests that the ability to feel orgasm is developed much early in life, way before puberty, separately from the ability to make sperms/eggs for sexual reproduction). I'd like to know how and why people drastically differ in terms of the time period at which they self-teach masturbation (ranging from as young as 5 years old to 20 or older). —Preceding unsigned comment added by 142.58.43.84 (talk) 18:15, 15 July 2010 (UTC)[reply]
I'm not sure there will be any particular reason for it. I guess most people discover the pleasure of masturbation by chance, which means it is entirely expected that different people will discover it at different times. --Tango (talk) 18:33, 15 July 2010 (UTC)[reply]
It is perfectly normal to discover it at a young age. As a child explores the world that surrounds it, it also explores its own body, what it is composed of, what abilities it has (walking, etc.). It's natural to also discover masturbation in this way. --Ouro (blah blah) 21:22, 15 July 2010 (UTC)[reply]
I'm not sure that this really fits within the Science category, so I apologize if this needs to be moved.
I remember reading a Wikipedia article a while ago, but I've completely forgotten the name of it. It was about a type of wind burst, for lack of a better term. I think it had an Arabic or Persian name. There was only one recorded instance of it occurring in the United States, in the 1800s -- the heat rose to shocking levels, and intense wind blew red-hot sand across California, to the point where hanging fruits were burnt and damaged on the side exposed to the wind. It drove everyone inside, where they were safe because of their adobe-walled houses (and "adobe-walled" was specifically mentioned in the article), but a man on a small ship off coast was either killed, or extremely badly burnt.
Does anyone know what I'm talking about? If someone could tell me the term so I can tell someone about the article, it'd be fantastic. If not, sorry for wasting the reference desk's time. 202.10.88.115 (talk) 20:36, 15 July 2010 (UTC)[reply]
I think that I was taught that the proper way to mix a solution in a volumetric flask is to put in the stopper, hold the stopper and then swirl it around while holding it upside down. Every time I do that, though, at least when I'm using a ground glass stopper, a little bit of the solution leaks out. Is there some way to prevent this or am I doing something wrong? I've noticed that the plastic stoppers don't seem to have this problem, but I've mostly got glass stoppers and I'm sure chemists didn't just let their flasks leak before plastic stoppers came along. ike9898 (talk) 20:40, 15 July 2010 (UTC)[reply]
A ground glass stopper should not leak! You obviously have the wrong size stopper. A common error is to use a stopper marked with a single size number (e.g. 19) in a joint where there are two numbers marked (e.g. 19/22) – a 19 stopper will go into a 19/22 joint and look like it fits, but it will not be watertight. Check that the ground part of the stopper fits the whole of the ground part of the joint – you might have to search around lab drawers for stoppers that actually fit! Physchim62(talk)21:23, 15 July 2010 (UTC)[reply]
Rubber stoppers aren't really a good answer anyway - rubber (or even plastic "rubber substitute") reacts with too many things. Glass is fairly inert. SteveBaker (talk) 23:15, 15 July 2010 (UTC)[reply]
The plastic stoppers for volumetric flasks are usually hard PTFE, which is usually inert enough for anything you would usually use a volumetric flask for. They do have a tendency to get stained by permanganate though. Physchim62(talk)00:34, 16 July 2010 (UTC)[reply]
Well, I'm pretty sure I'm using the correct size stoppers, but what about the mixing technique? I've always tried to do what I was shown in an O Chem lab 18 years ago - invert and sort of swirl the bulb around. Doing it this way the flask has to stay upside down for at least several seconds. Since asking this question, I've Googled around and failed to find any mention of this mixing technique. A few sources mention inverting the flask very briefly, several times. ike9898 (talk) 00:52, 16 July 2010 (UTC)[reply]
I've heard of that technique – I was probably taught it at some point or other – but I've never used it myself and I didn't teach it when it was me doing the teaching. A little trick to remember is that it is virtually never necessary to dissolve anything in a volumetric flask, so you only need enough mixing to get a homogenous solution. That you can acheive by briefly inverting the flask a couple of times. Physchim62(talk)01:06, 16 July 2010 (UTC)[reply]
Makes sense, except that the more I learn about mixing, the more I believe that it takes more effort to achieve homogeneity that intuition would tell me. I think I'll just make it a practice to briefly invert, but do it many times. ike9898 (talk) 13:29, 16 July 2010 (UTC)[reply]
Why not? If one particle collapses into a certain state, the other particle instantly collapses into the corresponding state, regardless of the distance between them. --138.110.206.100 (talk) 21:27, 15 July 2010 (UTC)[reply]
Isn't that precisely, exactly, why quantum entanglement is so exciting? Because it allows for faster-than-light information transfer, and hence potentially faster-than-light communication? At the least, I'd expect a reference or elaborated answer from some giving such a categorical answer on the science desk. 86.163.212.254 (talk) 21:52, 15 July 2010 (UTC)[reply]
See our article on quantum entanglement. While there is apparently a FTL state change, no useful information can be transferred without some kind of separate key, which must be transmitted normally. — Lomn21:59, 15 July 2010 (UTC)[reply]
The collapse of the wavefunction chooses randomly among the possible states, so even though the measurement at one end allows you to predict the properties of the partner particle, the individual states presented are essentially random. Consequently, we don't know of any way to control the process, even in principle, that could convey non-random information to the other observer. There are subtleties about why different communication strategies fail, but so far we don't know any way to exploit quantum entanglement to send usable information faster than light. Dragons flight (talk) 22:19, 15 July 2010 (UTC)[reply]
Couldn't you collapse multiple particles until the number of particles with the intended state is greater than the number of particles with the other state? The other person would count the number of particles with each state and determine which is greater. --138.110.206.102 (talk) 23:11, 15 July 2010 (UTC)[reply]
(ec) Consider the classical equivalent: make some red/black playing card pairs (to use Steve's suggestion) and then look at your cards until you've seen more red than black (or more black than red). The other person, looking at their cards, can't tell when you stopped looking. The quantum case is the same. In fact, the quantum version of this experiment is the classical version. To get any peculiarly quantum predictions you need to have a choice of noncommuting bases for your measurement. That aspect of entanglement is often omitted from popularizations, even though it's the only part of the thing that's actually quantum. Instead they give you plain old classical correlation—Steve's red and black cards—presented as though it were new and amazing.
Communication via entanglement is provably impossible in mathematically rigorous formulations of quantum mechanics. The Standard Model has no mathematically rigorous formulation and it's not technically possible to prove anything about it, so maybe one could try to argue that it's an open question there. But any obvious way to do it would also work in rigorous quantum theories, and hence is already ruled out. -- BenRG (talk) 00:09, 16 July 2010 (UTC)[reply]
For some reason, this confuses a lot of people. Perhaps it's wishful thinking or willful misunderstanding - but FTL communication it ain't. If you actually read Quantum_entanglement#Concept and the following section Quantum_entanglement#Other_Interpretations, this is all spelled out very clearly - with the conclusion: "However, because the method involves uncontrollable observation rather than controllable changing of state, no actual information is transmitted in this process. Therefore, the speed of light remains the communication speed limit".
So you and a friend both have one of the two entangled particles. You measure the state of yours and the answer is "A" - and if your friend examines his, it'll be "B". He knows the state of your particle and you know the state of his. But that's no different than if you'd taken two playing cards - one red and one black, mixed them up and sealed them into two envelopes before you moved away from each other. When you opened yours and found it was red - you'd know the state of your friend's card is black...but that information doesn't allow you to communicate any new information. Since the act of examining the particle forces the entanglement to collapse - you can't even tell when the other person examined their particle. There really is no way for information (or mass or energy) to exceed the speed of light. SteveBaker (talk) 23:12, 15 July 2010 (UTC)[reply]
Read my above post. You can't control the state of each particle, but you can control whether you collapse another one or stop. Once the majority are collapsed to the state you want, stop. --138.110.206.102 (talk) 23:21, 15 July 2010 (UTC)[reply]
Yes, but the supposed recipient of the message has no way of telling how many particles you ended up collapsing -- unless you send him a message to tell him, which sort of defeats the purpose. Looie496 (talk) 23:26, 15 July 2010 (UTC)[reply]
No. All you can do is make a measurement. If the particle is entangled it will collapse, but you have no way of knowing whether the result you get occurs because you collapsed the wavefunction or if the wavefunction had already been collapsed from the other end. Dragons flight (talk) 23:46, 15 July 2010 (UTC)[reply]
That's not quite accurate, DF. @138: The act of measuring the state "collapses" the uncertainty, but since the particles are entangled, the friend could tell the state of his particle without observing it by ... asking the first person what the measured state of his/her particle was! Of course, the question and answer are limited to light speed communication, so that's a dead end as well. --RexxS (talk) 00:00, 16 July 2010 (UTC)[reply]
Yeah, I'd guess some sort of lens effect. Note that it doesn't match the contours of the lunar terrain that it's superimposed on. — Lomn21:58, 15 July 2010 (UTC)[reply]
This page says "Note that the blue coloration at the top right is undoubtedly an artifact." - which isn't exactly helpful. On this page you can read what Bean and Conrad were saying to each other when the photo was taken. Pretty boring stuff, definitely not: "OMG! That alien spaceship is firing at us with it's high power blue space-laser! <bzzzzttttt>"! In this wider shot (which was two shots before that one on the same roll of film: [16] you can see that the sun was shining from above and to the right - so the odds are good that this is some kind of reflection from inside the camera or a lens flare of some kind. SteveBaker (talk) 22:37, 15 July 2010 (UTC)[reply]
Sorry - we're not allowed to answer that - you're asking for a medical diagnosis and we're specifically not allowed to provide one (see the note at the top of the page). If you are worried about it, you should consult a doctor. SteveBaker (talk) 22:21, 15 July 2010 (UTC)[reply]
Yeh, it took awhile to figure out what the OP was asking about. It would require a doctor to figure out if it's a bunion or just her natural boniness. The best bet is for the OP to read that article and take his own best guess. Or he could write a fan letter and ask. I'm sure such a letter would get a quick reaction. ←Baseball BugsWhat's up, Doc?carrots→ 23:45, 15 July 2010 (UTC)[reply]
Steve, why should I consult my doctor? Do you really think that it's me on this photo? That I posted picture of myself with my tits almost out? 83.31.97.1 (talk) 23:56, 15 July 2010 (UTC)[reply]
Because: (a) You use an anonymous IP address, so we don't know whether you are this person or not (b) you can ask a doctor for a medical opinion - it doesn't have to be you that you're talking about (c) our policy about not diagnosing medical conditions requires that we suggest consulting a doctor and (d) if you're looking at that picture and you're worrying about bunions...you might need to see a doctor! :-) Either way, it doesn't matter. We aren't allowed to diagnose medical conditions - period. SteveBaker (talk) 12:13, 16 July 2010 (UTC)[reply]
(Not a diagnosis, and not medical advice:)When my feet looked like that, the podiatrist did surgery for bunions. Fortunately, my boobs never looked like that. (See Gynecomastia (Not medical advice)) Edison (talk) 04:27, 16 July 2010 (UTC)[reply]
Chocolate Liquor
My understanding is that when the beans are taken from the tree, the are left to dry, and undergo fermentation. So, (believing that fermentation always results in ethanol) it would be logical to presume that chocolate naturally contains alcohol, without any being added. So if anybody can enlighten me to whether the alcohol is removed, or maybe even if there is a brand of alcoholic beverage from chocolate (without being added). 99.114.94.169 (talk) 23:23, 15 July 2010 (UTC)[reply]
Fermentation does not always result in ethanol. Fermentation merely means the action of microbes (yeasts, molds, and bacteria) on a foodstuff. There can be any number of products of fermentation; sometimes it is ethanol but it could be vinegar or cheese or any of a number of other compounds. In cocoa fermentation specifically, there is a two stage fermentation. Yeasts produce ethanol, which is consumed by bacteria and further modified to produce lactic and acetic acids. Coincidentally, this was covered in some detail earlier today in the "Candy" episode of Modern Marvels on History Channel, which is why I remembered it. --Jayron3223:54, 15 July 2010 (UTC)[reply]
Funny, because I saw it too, and while I was reading your response, I noticed how similar it was to the episode... well I must of missed that part, but thank you. So, are there any alcoholic beverages using chocolate? 99.114.94.169 (talk) 23:58, 15 July 2010 (UTC)[reply]
Not only does fermentation not always produce alcohol, it also doesn't always require microbes. Black tea and salami are two examples of foods produced by non-microbial fermentation. Looie496 (talk) 03:29, 16 July 2010 (UTC)[reply]
This may be controversial. Our article on Black tea states: 'This process is also called "fermentation", which is a misnomer since no actual fermentation takes place.' My impression of salami production suggests to me that at least historically, they were certainly not sterile during their "fermentation". -- Scray (talk) 03:41, 16 July 2010 (UTC)[reply]
Foods that are "air dried" or "air cured" most certainly have access to wild yeasts and other microbes, and absolutely could be fermented. Sourdough bread is one classic example. But salamis which are hung to dry and ferment would be another. --Jayron3204:47, 16 July 2010 (UTC)[reply]
Is there an easy way to estimate genes in genetics?
Let me explain. Say a man marries a woman and they have kids. The man has black hair and the woman has brown hair. For this we'll say black (B) is dominant over brown (b). Say the man has Bb and the woman has bb. Is there an easy way to figure out what hair color their children would have? I'm fairly new to genetics, so I need some help. Thanks! RaptorLet's talk/My mistakes; I mean, er, contributions00:43, 16 July 2010 (UTC)[reply]
In your example (assuming the false genetic determination of hair colour, but that's unimportant), each of the couple's children would have a 50% chance of having black hair (Bb) and a 50% chance of having brown hair (bb). That's because all the woman's eggs will carry the b gene, while half the man's sperm will carry the b gene and the other half the B gene. So the couple could have three brown haired children or three black haired children: the probability of either of those cases happening is 12.5% (50%×50%×50%). Physchim62(talk)01:36, 16 July 2010 (UTC)[reply]
Any combination thereof would be possible (i.e. 2 brown haired, one black haired, two black haired, one brown haired). Falconusptc04:20, 16 July 2010 (UTC)[reply]
When you are in your car and the person in the car next to you blasts their rock music, your car vibrates in your ears. Is that sound waves? Please answer me!!Diver62 (talk) 00:49, 16 July 2010 (UTC)[reply]
Is this a blast furnace or some other sort of furnace?
Is this pictured object a blast furnace? According to sources I have on it (I'll be adding an article once I know whether it's a blast furnace), this furnace was used to produce iron, using coal and charcoal for fuel. Our article on blast furnace doesn't show any furnaces like this one, but I've found pictures of many more, such as this one. Nyttend (talk) 03:36, 16 July 2010 (UTC)[reply]
It could be some type of Bloomery. The designs of blast furnaces are VERY varied from culture to culture and time to time. Depending on the age and location, it could very well be a smelting furnace of some sort. Just about any metal-using culture would need a furnace of some sort for smelting purposes. --Jayron3204:44, 16 July 2010 (UTC)[reply]
The other day I was looking at Venus with my 6.25" reflector. I was hoping to see it as a crescent. All I could see was a very bright spot, with all three eyepieces. Is Venus just too bright for that? Bubba73(You talkin' to me?), 04:11, 16 July 2010 (UTC)[reply]
Venus is very bright at present. Aspects of Venus shows that the next time of greatest brilliancy is on 27 September 2010, less than three months away. Venus will continue to get brighter and remain very bright from August to January, and then fade after that. Dolphin(t)04:18, 16 July 2010 (UTC)[reply]
Over the next few months Venus will be visible with the naked eye during the day. It appears much less bright during the day. Try viewing Venus through your telescope during the day and you might be able to see the exact outline, crescent or whatever. Dolphin(t)04:26, 16 July 2010 (UTC)[reply]
As of now Venus is slightly gibbous, i.e. slightly more than half full (which is harder to see clearly than when it's a crescent), but in your telescope you should be able to see the shape: it will soon (mid-August) go through 'half' phase and then become an increasingly larger but thinner crescent over the following two months. Likely the brightness will be causing you some problem; also, if you're looking when Venus is quite near the horizon, atmospheric distortion will blur the shape, so Dolphin's suggestion of daylight viewing, which reduces the contrast and places the planet further from the horizon, will help - but be very careful not to let your telescope point at the Sun - even an accidental glimpse could permanently damage your eyesight! It's also possible that your telescope may have slipped out of good collimation and not be focussing accurately - have you tried checking that it's still showing stars as good point images? How well is it showing Mars, which is only about 15 degrees to the east of Venus (but which is very near (92%) full) right now? 87.81.230.195 (talk) 06:23, 16 July 2010 (UTC)[reply]
Maybe it is just too bright right now. I may try putting in the Barlow lens and see if that helps cut down the brightness. I'll try before it gets completely dark too. Bubba73(You talkin' to me?), 15:58, 16 July 2010 (UTC)[reply]
The Barlow lens might indeed work, in that increasing the magnification (on the same aperture) decreases the brightness. On the other hand, it will also magnify any atmospheric distortions, telescopic aberrations and telescope/mount vibrations. Something you might also try is stopping off some of your aperture by putting a partial mask on the front end of your tube (typically, a cover with a small - say 2-inch diameter - hole, off-centre to avoid the secondary mirror of what I'm guessing is a reflecting 'scope). This also reduces the image brightness, and may reduce some optical aberrations if they're part of the problem. Good luck!87.81.230.195 (talk) 18:13, 16 July 2010 (UTC)[reply]
I saw Venus in my 4.5" telescope recently, and was able to observe the cresent quite well. My telescope also has a mask that reduces the frontal aperture to a mere 2", and this is useful for brighter objects. If your telescope doesn't have that, you can try a telescope filter that blocks most of the light so the image will be darker and easier to see, or it could be poor atmospheric seeing disrupting your view. ~AH1(TCU)18:27, 16 July 2010 (UTC)[reply]
How do fish drink?
The question just popped into my head. Do they every once in a while just take a gulp? Do their bodies simply absorb a certain autonomically regulated amount through their skin? their gills?--162.83.139.249 (talk) 04:34, 16 July 2010 (UTC)[reply]
Fish do not drink; they get all the moisture they need through their food, but they can also absorb water through their skin. (This applies to freshwater fish as well as to saltwater fish.)--Shantavira|feed me05:38, 16 July 2010 (UTC)[reply]
You can etch it, with either conventional tools, laser etching, or a solvent. We used to CNC a lot of HDPE and we would always put in a mark or ID on each piece with the tool. A dremel will do the trick, or even a razor or screwdriver (depending on how nice you want it to look). You should be able to make a thin enough etch that it won't puncture the bottle. Nimur (talk) 15:29, 16 July 2010 (UTC)[reply]
is there something wrong in the way I've corresponded to scientists?
I've written to at least a dozen different researchers concerning various inquiries or leads, often asking them if they know any suitable colleagues if they're not suitable or too busy. I was wondering if there's something wrong in the way I craft my emails. Too direct? Not distinctive enough? Do they not take emails from rising third year undergrads seriously?
For example, yesterday I was supposed to get some algae samples from another researcher, along with their species names, to do some plasmodesmata / cytoplasmic channel experiments. So on Thursday afternoon I wrote something like this:
subj: Just a small inquiry =)
Hi,
I was wondering about news if the algae samples were ready yet; or just their biological classifications. Perhaps I could come over to your lab or office when they are ready?
Thanks so much!
--
John Riemann Soong Lüwen
Biochem, Cogsci UVA '12
The e-mail is extremely informal to the point of rudeness for people you don't know who are professionals, and it sounds like you are an undergrad who expects them to drop everything they are doing to interpret and act upon your e-mail, which you have spent very little time working on. You are writing to them as if they are another undergraduate; it's very inappropriate for an academic setting. Here is a more appropriate e-mail:
subj: Algae samples
Dear Dr. [Name],
I am a third-year undergraduate in the biochemistry program here at [wherever]. I recently heard that your algae samples had been prepared, though there was some ambiguity for me over whether the samples themselves were ready, or just their biological classifications. Can you confirm this for me? If they are ready for pickup, would it be possible for me to pick them up at some time that was convenient to you?
Thank you for your time,
John
--
John Riemann Soong Lüwen
Biochem, Cogsci UVA '12
Notice that I have written this as if it were from one professional to another, not a kid to another kid. Smiley faces, exclamation points, lack of a name or title -- these are not appropriate for professional correspondence with people you don't know fairly well. If you look like you just dashed off the e-mail without thinking about it, they are likely to ignore it without thinking about it. --Mr.98 (talk) 16:12, 16 July 2010 (UTC)[reply]
Professional communication - we have an article on everything. Bear in mind the difference between an inquiry to somebody you don't know; a technical report / technical request to somebody you work with; and an informal communication unrelated to work with your professional colleagues. Nimur (talk) 16:30, 16 July 2010 (UTC)[reply]
Whatever you do, don't use silly smilies when talking with "adults." Things like =) just say "this person does not take this seriously" to basically anyone older than 22, as far as I can tell. If your e-mail screams "I do not take this seriously," don't expect them to take it seriously, either. I will note, anecdotally, that this is something that many people of "current undergraduate age" seem to not understand. A lot of the older academics and so on blame it on the "kids" never learning how to write formal letters (which used to be taught about a million years ago) or being extremely used to e-mail as an informal means of communication, and not ever being taught how to modulate their formality according to circumstance. I don't know how much I buy the "these kids today" types of arguments, but there is probably some merit to it. You should generally err on the side of formality in situations where you need something from someone who has more stature than you (whether "stature" is measured by age, position, education, power, what have you). If you go too far into formality, they will say, "oh, just call me Bob," and you'll have some idea where you stand. But you won't go bad treating people with respect, as if your communication to them is important, and as if their time was valuable to you. You can go very wrong with being too informal—it is an insult and an irritation to have someone demand something of you without treating you with a modicum of respect, at least in the USA. --Mr.98 (talk) 17:50, 16 July 2010 (UTC)[reply]
Speaking as a nominal adult, I find this tragic and would much rather receive the first version with the silly smiley than the long-winded and stuffy second version, regardless of how important a person I might be. I wonder if maybe you are falling foul of heavily restrictive spam filters, the kind which put all emails in the trash if they don't come from a whitelist of addresses and domains. This has happened to me in the past when sending emails to a scientist friend at his lab address; took me a while of feeling snubbed before it became clear what was going on. 81.131.47.121 (talk) 19:30, 16 July 2010 (UTC)[reply]
I don't know about that. When emailing someone (as with any form of communication) you should use the appropriate "tone" (not sure if that's the right word.). If you were actually chatting to the guy, you wouldn't be the same way you are when you're chatting to your friend over a beer - why would you treat them the same over email? Zain Ebrahim (talk) 20:32, 16 July 2010 (UTC)[reply]
But if I did talk to him face-to-face in an informal manner, would be completely blank me and walk away? If so, well, he's a very special individual. 81.131.47.121 (talk) 20:53, 16 July 2010 (UTC)[reply]
He probably wouldn't completely blank you, but he might just say "Sorry, I'm busy at the moment. Please come back later." and then walk off. With email, there isn't the same assumption that you should get some kind of immediate response. If you don't want to respond straight away you can just ignore the email until you get around to dealing with it. If you talk to someone in person, social norms require them to respond immediately in some way. --Tango (talk) 21:09, 16 July 2010 (UTC)[reply]
Writing and face-to-face are very different forms of communication and have very different social norms attached to them. Additionally, academia is a place that is based on hierarchies, hierarchies which take a lot of time and effort to get to higher rungs of. It doesn't really matter whether one likes this or not — this is how it is, and if you want to communicate with academics, much less be one, you have to learn how to navigate the system on its own terms. There are some individual academics who obviously are different about such a thing, but you never err by being overly respectful. Personally I have found this to be true in general, 81.131's sentiments to the contrary. People like to be treated as if they are important, 99% of the time. They might not always dislike being treated as a friend or an equal, but it can be jarring and often inappropriate. (One always knows when a con is going down if you are on the street and someone you don't know walks up with a friendly face and says, "My man! How are you doin'! Let me talk to you for just a second...") --Mr.98 (talk) 21:55, 16 July 2010 (UTC)[reply]
But the algae samples ... you don't ignore the serious part of a message like that just because it began "Hi!" and you didn't like it. That would be extremely petty. Perhaps he is one of those people who is averse to emails of all kinds and functions by phone calls only. 81.131.47.112 (talk) 23:53, 16 July 2010 (UTC)[reply]
Even the serious part does not reflect seriousness. The entire e-mail stinks of informality. It does not give respect, and does not recognize that there is zero reason for this person to do what they are asking (they are not, for example, selling a service). If you are asking someone to do something for you that they do not need to do, you should be respectful. The e-mail for an academic would be perceived as rude and disrespectful. --Mr.98 (talk) 20:23, 17 July 2010 (UTC)[reply]
Keep in mind that among academic scientists you will encounter a relatively high proportion of people with sub-average communication skills. You might encounter those that don't seem to understand the subtext of something that is said. Just try to be professional and explain your self as well as you can. ike9898 (talk) 17:14, 16 July 2010 (UTC)[reply]
I don't think it has anything to do with that. If you were writing to academic historians you'd have the same (lack of) response if you sent that e-mail. It is just heavily outside the norms of communication that academics are used to in a professional setting, and it confirms any doubts they might have that undergraduates don't take them seriously. (And academics are a sensitive bunch.) --Mr.98 (talk) 17:56, 16 July 2010 (UTC)[reply]
Actually, in my experience, American academics still tend to go for commas much more often than colons, though the reverse might be the case overseas (foreign academics often communicate more formally in general). That's just my personal experience so take it with the appropriate grain of salt. Dragons flight (talk) 18:37, 16 July 2010 (UTC)[reply]
I don't know its ultimate origins, but the use of the colon is fairly common in business and legal correspondence. The comma is seen as less formal. Dragons flight (talk) 21:20, 16 July 2010 (UTC)[reply]
I don't think that kind of minor Miss Manners stuff is really what is at issue here. What matters is the overall tone and extremely colloquialisms (like smileys). Your academics in question probably don't know the Miss Manners stuff, but they do know when they are being talked to like a peer, which is inappropriate unless you have been invited to do so (either explicitly or implicitly). --Mr.98 (talk) 21:55, 16 July 2010 (UTC)[reply]
It's not really an issue of formality. You're asking somebody to take some trouble to help you, but you haven't put any effort into it, and you're not offering anything in return, not even gratitude. People are often willing to help when it is treated as a special favor, but nobody likes to be treated as though it's their job to help you. The same thing applies to people who answer questions on Wikipedia, by the way. Looie496 (talk) 23:17, 16 July 2010 (UTC)[reply]
You can also just pick up the phone and call the person who can help you. If you need to communicate some details via email, you can always do that after you've spoken to the person on the phone. Count Iblis (talk) 23:23, 16 July 2010 (UTC)[reply]
Formality aside, I would point out that even for informal communication 'just a small inquiry' is inherently a bad subject line. Just as with the RD or any forum you should generally aim for informative subjects lines in e-mails no matter who you're communicating with and how well you know them or how informal you're being Nil Einne (talk) 12:16, 17 July 2010 (UTC)[reply]
Well, it's worse than that really. To me, "just a small inquiry :-)" immediately translates as "you have promised me something and you haven't done it, so I am politely reminding you". It's informative, only in the wrong direction. Looie496 (talk) 16:50, 17 July 2010 (UTC)[reply]
replacing and changing cell media while under a microscope
I want to change the cell media of observed human cells on a microscope slide while still on the microscope )we want to track particles at the same time so we don't want to lose our positions too much).
Trying to insert even a tiny syringe needle underneath the slip lifts it. And its an inverted microscope, so this makes it even more difficult.
Does anyone know how I could drill a hole in the cover slip or the glass slide maybe? Or how to work with extremely narrow capillary tubes? (They are so thin they are like 100 microns thick.) I don't know how to draw or pump fluid up or down them. John Riemann Soong (talk) 16:03, 16 July 2010 (UTC)[reply]
You'll probably need some type of microscrope flow chamber, which are specially made to allow you to mount a coverslip with your cells and apply different solutions. Some of these set-ups get quite fancy, with multiple ports, stage heaters, etc. You can buy them commercially or DIY. --- Medical geneticist (talk) 16:26, 16 July 2010 (UTC)[reply]
Depending on what type of experiment you're doing (and your budget), you can readily purchase virtually any type of fluid-handling slide you might need. If you don't need a coverslip above the cells, then you can use a chambered coverslip product like these ones. It's a slide-sized piece of coverslip glass (#1 or #1.5) with plastic wells sealed to the top, and a removable plastic lid. They come in a number of chamber sizes, and you grow the cells in the chambers right on the coverslip glass. Since it's a coverslip on the bottom, you can observe the live cells at an inverted microscope while they're still bathed in medium. In a similar vein, this company sells small petri dishes (35 and 50 mm diameter) with a small circular hole cut in the bottom. The hole is sealed with a coverslip glued to the bottom of the plate; again, you can image living cells (and add and remove medium!) right at the inverted microscope. In a pinch (if your funding doesn't allow you to purchase these dishes) then it should be possible to construct workable substitutes using your own petri dishes, coverslips, and waterproof non-toxic adhesive.
Now, if you're doing some sort of more complex fluidics, or you need the liquid to be confined to a narrow space, then those chambers I've described won't work. I've seen premanufactured coverslips with all sorts of interesting fluidics on them, but my mind is blanking on the names of manufacturers. TenOfAllTrades(talk) 21:06, 16 July 2010 (UTC)[reply]
DOLPHINS
How can dolphins dive so deep? Some dive even deeper than the photic zone and dolphins withstand all that pressure upon them. Why aren't people like them? Is their skin tougher or their body denser or what? I know dolphins are friendly and one of the most intelligent. I love dolphins!!!!!!!:)—Preceding unsigned comment added by Diver62 (talk • contribs) 16:37, 16 July 2010 (UTC)[reply]
It seems that with your overt obsession with dolphins :), you've overlooked that a number of organisms can dive much deeper and much longer -- such as the sperm whale. I'd suggest reading up on the sperm whale, as you might find more info relating to them on this topic, as it seems it's a much bigger deal regarding these organisms. DRosenbach(Talk | Contribs)16:43, 16 July 2010 (UTC)[reply]
Shame on you,DRosenbach. I know the sperm whale is a wonder, but i decided to ask about dolphins. Please answer my original question. You know, I love marine biology and cetolgy. that is everything in the sea.Diver62 (talk) 16:49, 16 July 2010 (UTC)[reply]
Shame on me?! What does that even mean? Being somehwhat similar creatures, it is exceedingly likely that whatever permits the sperm whale to accomplish such tasks similarly permit dolphins. Now cut being a clown. DRosenbach(Talk | Contribs)19:06, 16 July 2010 (UTC)[reply]
The deer in our back yard come out of the woods even in the day and eat up all the pansies outside the vegetable garden in the back. If you put human hair on the ground will they not come by or eat anything, or is that just an old wives tale?? Answer requested immediately?'Bold text'—Preceding unsigned comment added by Diver62 (talk • contribs) 16:46, 16 July 2010 (UTC)[reply]
No
This is not a science question, and the Reference Desk is not a chat room for opinions like this. --Sean17:00, 16 July 2010 (UTC)[reply]
I think the Science desk is as good a place as any for this question, as it deals with animal behavior. This site claims that the only guaranteed way to keep deer out is to build an 8 foot high (!) fence. It has other suggestions that sound like less work (although "get a dog" is actually probably more work). Comet Tuttle (talk) 17:43, 16 July 2010 (UTC)[reply]
The question I was responding to was "What is your opinion on police?", by the same user as this one, who later deleted part of that section. --Sean17:58, 16 July 2010 (UTC)[reply]
(It's really pointless to say things like "Answer requested immediately" and "PLEASE, I NEED AN ANSWER!!!!!!!!!!!!!!!!". This service is supported by volunteers - we answer when we have time, when we feel like it, when we have a good answer, when there's nothing good on TV, when the question is particularly interesting, whenever. Demanding answers on particular timescales or in particular ways (eg saying "Shame on you,DRosenbach" - when this was actually a highly relevant answer) just pisses people off and results in worse service - not better! You might also want to ration yourself to the number of questions you ask - you've been asking a lot recently, and that upsets people: particularly when the answer can easily be found with just a couple of minutes searching. Your questions below about sea snakes and jellyfish could easily have been answered just by typing those words into the Wikipedia search box and reading what comes up as a result. This service is really here for answering questions that are too difficult to answer that way - or which require tricky interpretation of hard-to-understand articles. Either way, being overly demanding and upsetting the volunteers never ends well!) SteveBaker (talk) 19:04, 16 July 2010 (UTC)[reply]
Cactus
How long does it take for a cactus to mature? I know some of them can live 300 years. I wondered since i have a cactus garden!!Diver62 (talk) 17:23, 16 July 2010 (UTC)[reply]
Wow! Does cactus still look the same even when its dead? because i think part of my cactus is dead, but it looks alive.Diver62 (talk) 18:21, 16 July 2010 (UTC)[reply]
It depends on what type of cactus. Green ones will generally turn brown. The more succulent the cactus, the more obvious it will be when it loses moisture. -- kainaw™18:30, 16 July 2010 (UTC)[reply]
it is green on the top of the plant, and brown on the bottom! it gets fertilized once a month in the summer, and water once a month the rest of the year. Help!Diver62 (talk) 18:33, 16 July 2010 (UTC)[reply]
That's not a good sign. I had a cactus that died on the bottom, but the top stayed alive for a very long time. The roots were dead and it fell out of the soil, but it stayed green on top for quite a while (since they can live without water for a long time). Are you sure water once a month is the right plan for them? You should check. Ariel. (talk) 23:24, 16 July 2010 (UTC)[reply]
I have a minor molecular biology dilemma. I've created a mutant construct based on the HPV type 16 genome with specific point mutations (two silent mutations that create restriction sites, and a non-sense+frameshift in the L1 major capsid open reading frame that renders the virus non-infectious). Here's the problem: what do I name this thing? I can't seem to find any documented nomenclature for DNA constructs that are minor modifications of naturally existing episomes, so I figured I would try to tap the collective wiki-wisdom. – ClockworkSoul18:06, 16 July 2010 (UTC)[reply]
I don't think there is any specific nomenclature. An example that came to my mind was the "synthetic genome" that the J. Craig Venter Institute created (covered here). They named one of their genomes JCVI-1.0, so perhaps you should just name your construct with initials and a number? Something like HPV16-CwS1.0. For smaller constructs, most people try to make up a name that is short but includes some important information. Maybe you could convey that L1 is disrupted: HPV16-L1X. --- Medical geneticist (talk) 11:47, 17 July 2010 (UTC)[reply]
This site is semi-official, but doesn't even come close to your nomenclature problem. After all, "HPV type 16" is only a conventional name, not one that the powers-that-be have got around to approving. Physchim62(talk)15:39, 17 July 2010 (UTC)[reply]
Jelly fish are not active predators - they will sting anything that swims into their tendrils, but don't go seeking prey out. --Ludwigs218:38, 16 July 2010 (UTC)[reply]
i didn't know that.It isn't tendrils. That's reserved for plants. It's tentacles. what if everything avoids them and doesn't swim into their tentacles? Diver62 (talk) 18:44, 16 July 2010 (UTC)[reply]
Lacking either brain or central nervous systems, jellyfish don't "think". When their tentacles contact something, it acts by itself - the stinging cells (nematocysts) will automatically sting anything they touch - but they aren't "thinking" about it. Furthermore, not all jellyfish can sting. Many that can sting produce toxins that humans are completely immune to. On the other hand, some produce toxins so powerful that they can easily kill us. Our jellyfish article is really good - you should read it. SteveBaker (talk) 18:54, 16 July 2010 (UTC)[reply]
Box jellyfish and especially Irukandji jellyfish can be very dangerous. Their tenticles can activate venom that attacks every system in the body and even ruptures the blood cells it comes into contact with. Also, research shows that jellyfish do have "eyes" that can see, but no central nervous system to process the information. ~AH1(TCU)18:57, 16 July 2010 (UTC)[reply]
When I went on a tour of Boeing's Everett, Washington facility, the tour guide at one point mentioned that one warm and humid summer day before the ventilation system was installed, somehow enough heat and moisture rose to the top of the 11-story tall factory (which is many, many acres as well...I believe the tour guide also said you could fit all of Disneyland inside the building) that clouds formed and it actually rained inside the facility. Is this even possible, and if so, what goes into making the building create it's own weather system? I was under the impression that it took more depth to an atmosphere than that to create clouds/rain, but I could be mistaken. Ks0stm(T•C•G)18:58, 16 July 2010 (UTC)[reply]
It has been reported that NASA's Vehicle Assembly Building (originally called the "Vertical Assembly Building") is tall enough to develop internal weather, as you will see at that article. But the Boeing Everett Factory, although huge, is not so high, and they didn't say anything like that about it when I took the tour. I think you're right to be skeptical. --Anonymous, 19:29 UTC, July 16, 2010.
I could imagine that some activities created hot humid air that condensed on a colder roof. That could have an effect similar to rain but wouldn't involve any clouds. I could easily imagine something like that happening and then being exaggerated in the retelling over the years. It does seem unlikely that one would see clouds after only 11 stories. Dragons flight (talk) 19:52, 16 July 2010 (UTC)[reply]
It would merely require the right temperature, humidity and air movements, which might well arise in such an unusual structure. It's entirely possible to do this deliberately in even a small enclosed space: for example, at the interactive science centre INTECH I visited a few months ago an open-fronted cabinet no more than a couple of metres square and maybe three high with these parameters actively controlled is used to create a mini-cyclone made visible by a mini-cloud*. Ordinarily, of course, buildings are designed to requirements that, deliberately or as a by-product, preclude the necessary conditions, but with the VAB other requirements, particularly a very large and high open space, are overriding so it might just stray across the boundaries permitting them. Given NASA's scientific ethos, it would be regrettable if such a long-standing claim was baseless. I do however agree that a reliable source statement should be sought for citation. 87.81.230.195 (talk) 22:37, 16 July 2010 (UTC)[reply]
Warm, moist air entering a cold building could condense on the structure and then drip, possibly in large amounts. It wouldn't be rain, exactly, but its effects would be the same. Acroterion(talk)19:24, 17 July 2010 (UTC)[reply]
fundamental forces
i have read the most basic of the standard model. i understood it well. the only doubt i have is that why does the effect of all the fundamental forces decrease over distance if force carrying particles like photons are involved? someone please throw some light.
--Lightfreak (talk) 19:49, 16 July 2010 (UTC)[reply]
First of all, they don't all decrease over distance. Electromagnetism and gravity both decrease by an inverse square law. The strong force has constant strength at all distances, although it always cancels out over any distance larger than an atomic nucleus - if you have two strongly interacting particles a larger distance apart the potential energy is great enough that two more particles will be created inbetween them and they'll cancel out the force. The weak force does something odd that I don't really understand (see fundamental force for some details). The reason electromagnetism, when considered in terms of photons, decays over distance is because you can think of it like lots of photons being emitted in all directions at all times. The number of photons at each distance will be the same, but they'll be more spread out at greater distances. That's exactly what happens for electromagnetic radiation. For electric or magnetic forces it's a little different, since you are dealing with virtual photons, but the principle is the same. --Tango (talk) 21:17, 16 July 2010 (UTC)[reply]
I have a bathroom sink with a wood cabinet below it. I am not sure what type of wood it is. There are certain small sections where the stain has come off. Can I touch these up with shellac? I do not want to use petroleum based stain. Can the shellac be applied to these sections? I can only assume the existing stain is polyurethane. If the shellac gets on areas of existing stain, will the shellac adhere to the existing stain or will it not adhere?
I do not want to have to sand off any existing finish or use paint stripper. Will the shallac work? How long does shellac take to dry? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 20:30, 16 July 2010 (UTC)[reply]
human body aging - what's happening when things begin to sag/stretch downwards?
A particularly old woman sat next to me on the bus yesterday who was not wearing a bra. She had the classic waistline breasts which had stretched and sagged over time far, far down her chest. Thinking about the internal anatomy of the breast, it occurred to me that this process was actually rather fascinating. How, exactly, does the body cope with this sort of thing? Clearly many things must get gradually longer over time, yes? Blood vessels, connective tissue, etc. Or are the cell counts remaining the same and the cells themselves actually lengthening? 61.189.63.171 (talk) 22:39, 16 July 2010 (UTC)[reply]
RoHS states in the criticism section Another criticism is that less than 4% of lead in landfills is due to electronic components or circuit boards, while approximately 36% is due to leaded glass in monitors and televisions (RoHS removed lead from most circuit boards but not leaded glass).
My question is - what are the comparitive dangers of lead solder (lead tin alloy), and leaded glass (lead oxide in silicate/lead silicate) - specifically in landfills or other waste disposal - or more specifically does leaded glass leach lead to any extent? (refs please if possible). Thank you.87.102.32.76 (talk) 00:02, 17 July 2010 (UTC)[reply]
Encasing in glass (vitrification) is one way of isolating hazardous materials from the environment. I wouldn't expect leaching of leaded glass to be a significant problem. --Carnildo (talk) 01:14, 17 July 2010 (UTC)[reply]
According to this link butterflies usually sleep in trees. And if memory serves me, butterflies don't really "sleep." They need sunlight to be active, and when there's a lack of sunlight, they go into a sort of resting state that's not exactly sleeping. They don't move around, but they can if they need to. The RaptorLet's talk/My mistakes; I mean, er, contributions01:41, 17 July 2010 (UTC)[reply]
Insects have a 24-hour rhythm of activity, see circadian rhythm. Specifically regarding sleep in insects: for bees, see this Nature paper. So bees clearly do sleep. I'd be surprised if lepidoptera don't. --Dr Dima (talk) 04:29, 17 July 2010 (UTC)[reply]
Moths in the daytime will probably be similar to butterflies at night. They just sit and rest. If you knock into them, they might fly for a little distance, but they land quickly and go back into their dormant stage. --Chemicalinterest (talk) 11:03, 17 July 2010 (UTC)[reply]
There is a very nice 1916 (!) paper by Rau and Rau, here, describing rest / sleep in insects. Very enjoyable to read, closer in style to J.-H. Fabre than to modern biology papers --Dr Dima (talk) 17:03, 17 July 2010 (UTC)[reply]
Getting peanut out of your body faster
I am mildly allergic to peanuts. If I eat them I don't swell up and die. But I do feel slightly out of breath and my joints ache (actually quite painful). Strangely, this only started about two years ago. Anyway, as you can imagine I do avoid peanuts. So I've been having my normal reaction to peanuts for the last few hours but I didn't eat any peanuts today. I was wondering what the hell was going on when I realized that maybe the fried chicken I had for dinner might have been fried in peanut oil. Sure enough, I looked up the restaurant online and, yup, peanut oil only. Anyway, I was wondering if there was anything I could do to make it get out of my body faster. Any suggestions? I've been drinking quite heavily (water that is).--162.83.139.249 (talk) 04:52, 17 July 2010 (UTC)[reply]
Yikes, we're just a bunch of semi-anonymous dopes with nothing better to do than answer questions from strangers. It sounds to me like you need some advice from an actual doctor who's examined you in person. If you're concerned about anaphylaxis, you should probably take your epi-pen and/or call 911/go to the hospital. Water wouldn't seem to be very helpful; oil and water don't mix, but don't take my word for it - ask the attending physician. Matt Deres (talk) 04:58, 17 July 2010 (UTC)[reply]
Nah, It'll pass in a few hours. Just really quite unpleasant. The worst part about it all is that I am in love with peanuts (mainly peanut butter). I used to eat PB&J sandwiches all the time. Maybe I developed the allergy from overexposure. Anyway, a really neat thing: I just read in Wikipedia's article on peanut allergy that they have developed peanut butter that has 100% of the allergen removed, though it isn't being marketed yet. I can't wait.--162.83.139.249 (talk) 05:03, 17 July 2010 (UTC)[reply]
I'm glad you're alright. If peas aren't a problem, you might want to see if your local grocer carries "pea butter". I've heard it's almost indistinguishable from peanut butter; you can even use it for making peanut butter cookies and the like. Matt Deres (talk) 16:35, 17 July 2010 (UTC)[reply]
Excuse me for ranting a bit, but this hits on one of my pet peeves. We don't give medical advice, but that doesn't mean we have to advise people to consult a doctor on every occasion. "Dear Wikipedians, I stubbed my toe and it hurts, what should I do?" "We can't give medical advice, consult a doctor." Nuts. It's sufficient to say that we don't give medical advice -- advising people to consult a doctor is in itself medical advice. And very often it's bad advice -- doctors are an extremely expensive resource, at least in the USA. And -- and -- okay, enough, sorry. Looie496 (talk) 19:31, 17 July 2010 (UTC)[reply]
Just been clipping my hyacinth macaw's toenails today. When you do it, you have to be careful not to knick the vein that runs all the way down the middle of the nail, apart from the last few mililmetres. What exactly is the purpose of this vein anyway? --95.148.107.17 (talk) 11:48, 17 July 2010 (UTC)[reply]
Your macaw's claws are not a solid keratin cone all the way through; they have a narrowing core of living tissue most of the way down, though it runs out before the extreme tip, from which the keratin grows, just as your own finger- and toe-nails grow from a nail bed of living tissue - human and other primates' nails are merely a specialized flattened form of claw. This living tissue needs a blood supply just like all such tissue. Apart from having a blood supply, this tissue will also have sensitive nerves (as you'll know if you've ever had a splinter under a nail), so cutting into this area may not only cause blood loss and damage that could result in future growth malformation of the claw, it will also hurt. 87.81.230.195 (talk) 16:35, 17 July 2010 (UTC)[reply]
Dementia.
Three years ago, my wife (now 64 years of age) was diagnosed as a Dementia patient. Her memory and motor co-ordination were affected. She now has no sense of balance and is confined to a wheel chair.Three months ago, she developed what I consider to be a unique problem. She constantly feels the urge to visit the toilet for a bowel movement. She has always been extremely regular, going to the toilet first thing in the morning, so that this latest development is extremely frustrating for both her and myself. To give some indication of the severity of the problem, I have been monitoring the number of times that I have to help her to the toilet on a daily basis. At present, the record stands at 51 times in a 24 hour period, with only one successful bowel movement. This has obviously affected our sleep pattern, so that we are now averaging a mere 3-4 hours sleep a night over the past two weeks.
I have used medication prescribed by my GP, neurologist and a psychiatrist, as I was informed that the problem was caused by a short-circuit in the brain. No medication has had the slightest positive effect.
I would like to know whether this problem has been encountered before and been successfully treated. If so, what medication or treatment was employed. —Preceding unsigned comment added by 196.30.31.182 (talk) 16:09, 17 July 2010 (UTC)[reply]
Given the OP is talking about such a serious problem and how past medication has failed, it's safe to assume that they have already spoken to a doctor. The best option is to continue seeing the doctor who has the best knowledge of your wife's case and talk about extending your current treatment arrangement or starting a new one. There's lots of information on the internet about dementia and it's treatment, but I must say that most forms of deteriorating dementia are not curable and are usually treated to sustain memory for as long as possible. I don't feel comfortable going into any more detail I'm afraid, so please go talk to your doctor. Regards, --—Cyclonenim | Chat 16:48, 17 July 2010 (UTC)[reply]
Besides, Draco, he wasn't even asking for medical advice, but medical information. Medicine is still a scientific topic that can be discussed. Even if the question is anecdotally phrased. —Preceding unsigned comment added by 92.19.107.38 (talk) 20:24, 17 July 2010 (UTC)[reply]
But it's so confusing with all the different prefixes and stuff. And the units are different magnitude than the regular units. 1 m isn't even close to 1 ft. --138.110.206.102 (talk) 17:22, 17 July 2010 (UTC)[reply]
Metric system units are easier to remember, as for example one metre is 100 centimetres, one tonne is 1,000 kg, and so on. It's also much easier to calculate than Imperial units, as it's difficult to remember how many feet there are in a mile but not so difficult to memorize the number of metres in a kilometre (1,000). ~AH1(TCU)17:27, 17 July 2010 (UTC)[reply]
Yes, but that's not easier to remember than the metric units. All names within this system are based on the main unit, and are in base ten. For example, there's nanometre, mircron (or "micrometre", that's an exception), millimetre, centimetre, decimetre, decametre, kilometre, etc. In Imperial, you have to remember the number of fluid ounces in a pint, pints in a quart, quarts in a gallon, and so on. You don't have to remember these confusing conversions in metric. Instead of using actual full names, all you really have to remember in a series of metric units is one name, and the prefixes. ~AH1(TCU)17:38, 17 July 2010 (UTC)[reply]
You may be able to remember how many feet there are in a mile, but many people can't. Without looking it up, can you recall the conversion factor between fl. oz. and cubic in., both of which are units of volume? If you made a calculation and the result came out to be 1,023,514 in., would you be able to convert it to miles (a more familiar unit for lengths of that magnitude) in your head? Do you remember the conversion factor between avoirdupois oz. and troy oz.? With the metric system, there are many fewer redundant units for the same types of quantities, and the system of prefixes is uniform for all types of units. --173.49.11.154 (talk) 18:17, 17 July 2010 (UTC)[reply]
(ec)It's interesting that you say "1 m not close to 1 ft"--somehow you've chosen the foot as the standard, and you have to memorize arbitrary conversion factors from it to everything else (12 inches, 1/5280th mile, 1/3th yard). And a whole different set of conversion factors for other types of measurements (for pounds, 16 ounces and 1/2000th ton). And another set for volume (quick! how many drams in a gallon?). With metric, it's the same conversions for everything...less to know. And doing powes-of-ten conversions is easy because it matches our whole numbering system (just shift the decimal point) rather than multiplying or dividing by "less round" values.
OTOH, the whole idea of a "comfortable/recognizeable" unit is important when you're trying to use both--you just chose the wrong correspondence. A meter is about a yard (so a meter is 3 feet, rather than a 1:1 for your natural base unit, and an inch is 2.5 cm). A liter is about a quart (so a gallon is 4 liters). A kilogram is about 2 pounds. DMacks (talk) 18:24, 17 July 2010 (UTC)[reply]
The metric system is an international decimalised system of measurement used by most of the world except only Burma, Liberia, and the United States. Did you read the article Metric system ? Cuddlyable3 (talk) 18:35, 17 July 2010 (UTC)[reply]
However, 1 metre is approx. 1.1 yards (or 1yard and 3⅓inch). If you are used to the metric system then the US customary system and the British Imperial system (they are slightly different) are inconsistent and awkward to use. Now let me see. There are 12 inches to the foot, 3 feet to yard, 2 yards to the fathom, 110 fathoms to the furlong, 8 furlongs to the mile. There are 16 ounces to the pound, 14 pounds to the stone, 8 stones to the hundredweight, 20 hundredweight to the ton. There are 1000 millimetres to the metre, 1000 metres to the kilometre. There are 1000g to the kilogram, 1000kilogram to the metric ton. Now which is simpler? CS Miller (talk) 20:09, 17 July 2010 (UTC)[reply]
The idea behind the metric system was, as Looie points out, twofold. First was to develop a universal standard, so that the US and the UK and France and Japan all knew that if you said something was a given length or weight, it was. This is in contrast to systems that were sometimes quite localized, and a "pound" or a "foot" could mean different things in different places. Second was to develop a system that was decimalized, because it is easier to do many calculations with decimalized systems than non-decimalized. 12 inches to a foot, three feet to a yard, dividing inches into 1/16ths, 5280 feet to a mile... this is a pain, quite arbitrary, and makes it hard to covert between units (how many 1/16ths of an inch are there in a mile? Not the easiest calculation to do in your head). Decimalization lets you just change prefixes and do things in orders of 10. That's pretty easy to do. As for what feels "intuitive" to you—it's entirely what you grow accustomed to using. I find miles intuitive but that's just because I've grown accustomed to thinking in terms of them. It's entirely arbitrary. Which is not to say that in all fields decimalization is easier; in time, for example, there is a strong argument that decimalization doesn't actually save much effort on calculations, and in fact impedes certain types of calculations. --Mr.98 (talk) 20:20, 17 July 2010 (UTC)[reply]
Nobody seems to have mentioned that it incorporates (not by chance) conversion factors of 1. eg 1 cubic meter of water weighs 1 metric tonne, or 1 cubic centimetre of water weights 1 gram (ie based on water of density 1 unit). also Move a force of 1 newton through 1 meter and you've done 1 joule of work. Compare with the various conversion factors for 1 footpound.87.102.32.76 (talk) 20:36, 17 July 2010 (UTC)[reply]
How portions of the brain are identified
In the left hemisphere of the brain are located Broca's and Wernicke's regions. Are the corresponding regions in the right hemisphere similarly named -- i.e. right hemisphere Broca's, etc. -- or are these right hemisphere regions referred to with specific designations. —Preceding unsigned comment added by 216.106.212.60 (talk) 19:53, 17 July 2010 (UTC)[reply]
Resolved
Resolved
Facepalm And I didn't even notice Gandalf61's answer above. Deor (talk) 13:02, 16 July 2010 (UTC)
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