Wikipedia:Reference desk/Archives/Science/2009 August 12

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August 12

Southern New Zealand

Do New Zealand usually get snow in the south? the south tip is 47 degrees away from equator, since it has marine climate I don't think it can get snow at land basin level. Can summer get up to like 70 F?--69.229.108.245 (talk) 00:45, 12 August 2009 (UTC)

Do you mean south island or the south of the south island? A lot of the south island gets snow in winter, they have permantent glaciers and the whole works. You're right about avereage summer temps being around 70f. Vespine (talk) 00:55, 12 August 2009 (UTC)

I mean south island. Land basin level like Irvine, CA ground level not moountain. I thought it is unlikely to get snow in valley-basin level, just mountain gets permanent glacier level.--69.229.108.245 (talk) 01:34, 12 August 2009 (UTC)

Looks like it snows all the way down to sea level -just not often.[1] 75.41.110.200 (talk) 01:45, 12 August 2009 (UTC)

The record high temperature for Christchurch is 42 C (108 F). —Preceding unsigned comment added by 75.41.110.200 (talk) 02:02, 12 August 2009 (UTC)

Punta Arinas is 53 South, the tip of new Zealand is 47 South in latitude. They don't get much snow, just occassionally (not every year) but bone-chilly!--69.229.108.245 (talk) 02:07, 12 August 2009 (UTC)

In Queenstown not much snow this year. Avg. is like 40s this winter, avg low of low 30s. Is just enough for oranges to freeze.--69.229.108.245 (talk) 02:11, 12 August 2009 (UTC)

Take a look at [2] or older dates [3] e.g. [4] and reach your own conclusions. You may be also interested in the individual monthly summaries [5]. Sadly this does not provide stuff like the mean temperatures for places other then a few main centres but you can get older data at [6], e.g. [7]. Beyond the data in the summaries, there are is no per location data for snowfalls that I'm aware of probably because you're right, it happens infrequently enough that it isn't of great interest to many people Nil Einne (talk) 08:41, 12 August 2009 (UTC)

In my 4 years in Dunedin (2004-2007), every year we had at least light snowfalls at sea level. In particularly cold years it can settle up to 5cm or so for a couple of days. It snows on the beaches too. Aaadddaaammm (talk) 13:26, 12 August 2009 (UTC)

hot ice on Uranus and Neptune

For a long time I always wonder what is a hot ice in Uranus and neptune's liquid layers. Is it a semi-solid junks? Does slush mean tarlike substance or I don't know what. Some scientist beielve Uranus and Neptune's mantle is made of molten rock, water and ice thoguh--69.229.108.245 (talk) 03:30, 12 August 2009 (UTC)

The sections Uranus#Internal_structure and Neptune#Internal_structure give pretty good descriptions. They say that each planet has a small core of molten rock and metal (since those are the densest) and then a liquid mantle above that of mostly water, methane and ammonia. These chemicals are referred to as "ices" but that doesn't mean they're in a solid or slush form. See Volatiles. Rckrone (talk) 04:12, 12 August 2009 (UTC)

Speed of sound in a fluid

According to my physics textbook, the speed of sound in a fluid is v=sqrt(B/ρ), where B is the Bulk modulus and ρ is density. How is this derived? Mo-Al (talk) 05:34, 12 August 2009 (UTC)

For one way to derive it, see section 31.4 in this book. Red Act (talk) 06:24, 12 August 2009 (UTC)

Conversely, one might say that the microscopic bulk modulus is defined by the macroscopic fluid speed. It depends which direction you consider more "basic" or "fundamental" - I think most fluid physicists would say that the bulk modulus, being essentially an implication of the molecular theory of gas (or liquid), is more fundamental than the sound speed. Nimur (talk) 20:58, 12 August 2009 (UTC)

IQ and Dunning-Kruger effect

Are people with a high IQ less prone to the Dunning-Kruger effect and Impostor syndrome? NeonMerlin 07:38, 12 August 2009 (UTC)

AFAIK the complexe d'imposture is more likely to affect people with a high IQ than others since it tends to affect people who are over-achievers to the point where their own success seems surreal to them. However, I am just basing the response on what I was taught on a "being an executive mentor" course a decade ago so this may be wrong (plus these people read psychology which is pretty sloppy as a science from the point of view of establishing "facts")--BozMo talk 09:40, 12 August 2009 (UTC)

OR: I have high IQ scores and often have feelings similar to the impostor effect, but I'm no over-achiever. I'm simply depressive.  —Tamfang (talk) 22:33, 6 October 2009 (UTC)

Reading the article on the Dunning-Kruger effect however seems to indicate that it is exactly the opposite: specifically it is much more likely to affect low IQ individuals. Given that these two are obvious opposites I hope this isn't a homework question. --BozMo talk 09:45, 12 August 2009 (UTC)

This paper seems to be relevant.--droptone (talk) 12:28, 12 August 2009 (UTC)

Viewing the Perseids meteor shower from Netherlands

I've read the article on Perseids meteor shower. It says that the meteors are more visible in the Northern Hemisphere. I'm in the Netherlands. What I'd like to know is where in the sky to look towards. I can look mainly north, toward the big dipper and northern star, or any other direction. I can look straight up, or more towards the horizon. Last night, I saw one meteor, in about 5 minutes watching, and it went directly across the face of the Big Dipper, more or less in the northeastern sky. Thanks if you have advice. —Preceding unsigned comment added by 80.101.134.43 (talk) 08:50, 12 August 2009 (UTC)

As noted in the article on the Perseids, the meteors of this shower appear to come from the constellation Perseus - so you want to be looking in that direction. To find out where the constellation Perseus is, look on a star map (for instance, here) - in the evening, Perseus will be low in a NNE direction, below Cassiopeia. — QuantumEleven 09:40, 12 August 2009 (UTC)

The radiant is in Perseus, so meteors closer to the radiant are faster and leave shorter trails; they're the ones which enter the atmosphere directly and quickly burn up. Farther from the radiant, the meteors are slower and leave long, impressive trails because they skim the atmosphere instead of plunging directly into it. You probably want to see some of those, so the best place to look is 20-40 degrees away from the radiant, not at it. --Bowlhover (talk) 09:20, 13 August 2009 (UTC)

If you find somewhere with a clear sky and not too much clutter on the horizon (ie not in the middle of tall buildings) - then head out there during the peak of the shower, you won't need to know which direction to look - it'll be pretty obvious as the meteors streak past. If Perseus is low in the sky for you (as QuantumEleven says) then the meteors will be just grazing the atmosphere. That means that you may not see so many as when Perseus is high in the sky - but those that you do see should leave long, impressive trails across a large fraction of the sky. SteveBaker (talk) 11:27, 12 August 2009 (UTC)

I usually lie on my back and look straight up. That way you catch lots of meteors with your peripheral vision. They can be a very long way from the radiant. Of course once the moon is up you need to look away from it, otherwise it will "blind" you.--Shantavira|^{feed me} 11:50, 12 August 2009 (UTC)

On the BBC yesterday it said if you find the Moon and look about 60 degrees away from it you should see the meteors quite clearly. I can't remember which direction to turn away from the moon, but you will of course be able to experiment for yourself! --TammyMoet (talk) 17:25, 12 August 2009 (UTC)

Time Dilation with Radioactive Elements.

I'm not too well educated in this stuff but from what I get time is dilated (slows down) for a observer moving with a speed v relative to an observer at rest (or otherwise). I know this has been confirmed with ultraprecise clocks on planes. I just was wondering if a guy gets on a plane with 100 grams on C-14 and goes at a speed so that each second for him is 2 seconds for an observer at rest (which I'm just estimating would be sqrt(.75c)). After 2 halflifes of C-14 for the observer at rest (11460 years) would there be 50 grams of C-14 (which means only one halflife worth of decay) left for the guy on the plane. I mean this just to be roughly 50 grams because I think that half-lifes aren't exact- that you can't exactly predict whether it decays or not (Schrodinger's cat?). Everything tells me it should be 50 grams but for some reason I was just curious. Has any test like this been done? 76.94.88.196 (talk) 09:10, 12 August 2009 (UTC)

Yes. The half-life is determined in the rest frame of the decaying element. The observer at rest will indeed have to wait two half-lifes to see 50 grams of C14 decay.

This is observed experimentally with muons in cosmic radiation : the muon is a very short-lived particle which is created in the upper atmosphere by cosmic radiation. Judging from the muon half-life, you would not expect the muon to reach the earth's surface, since it will have decayed long before that. However, the muons are very fast, and their time goes slower than ours. This is why muons do reach the earth's surface. —Preceding unsigned comment added by 81.11.170.162 (talk) 09:43, 12 August 2009 (UTC)

I believe there have also been experiments run in particle accelerators with decaying particles that verify the predictions of special relativity very precisely. --Tango (talk) 16:00, 12 August 2009 (UTC)

Ok thanks Tango that was what I was looking for. I knew about the muons but for some reason I kept thinking the radioactive elements would ignore special relativity (!?). 66.133.202.209 (talk) 16:34, 12 August 2009 (UTC)

Purpose of cylinder at back of Renault FT-17 tank

From the Humanities RD:

What is the purpose of the "tail" apparatus on this Renault FT-17 tank, including the cylinder and chains? (This tank is exhibited in the Compiègne Forest at the location where the armistice of the First World War was signed.)

From the side

From the back

David.Monniaux (talk) 10:27, 12 August 2009 (UTC) —Preceding unsigned comment added by Quest09 (talk • contribs)

The tail bit was used to aid the tank in crossing trenches. Bear in mind that the motor was located at the rear of the vehicle. Thus the tank could have moved its unsupported front over the gap of the trench without "toppling" over. I could not find any information on the purpose of the barrel and the chains. --Cookatoo.ergo.ZooM (talk) 11:00, 12 August 2009 (UTC)

The barrel and chains look kind of like a small, unassembled Mine flail. Very thin though. Fribbler (talk) 11:04, 12 August 2009 (UTC)

Yes, but this tank is from Great War and mine flail, according to the article, were first used in the WWII.Quest09 (talk) 11:10, 12 August 2009 (UTC)

Hmmm. No other pictures I found had these on it. Perhaps it was simply a spare fuel tank and tow-chains (the chains do have hooks) for salvaging damaged vehicles? Fribbler (talk) 11:16, 12 August 2009 (UTC)

Other stuff tied on at the back

The barrel doesn't appear to be a part of the tank per-se. None of the other pictures of the tank in our article show a barrel there. In the picture to the left here, you can see that there is a bunch of other stuff tied on at the back of the vehicle. I suspect that the crew simply used it as a place to conveniently stow things that they didn't have room for inside. (They were pretty cramped in there!) The barrel has "OIP" and then "30" written on the top. I could believe that it's a 30 litre barrel...but I have no idea what "OIP" means. Similarly, the chain (there is only one - the thinner one in the background is just a part of the exhibition area) may just be a tow chain or something - it has hooks at either end, so that's pretty likely. Those early tanks got stuck and broke down a LOT - carrying a tow chain would have been a good idea! These photos from Compiegne are really nice - they should be in our article about the tank somewhere. SteveBaker (talk) 11:19, 12 August 2009 (UTC)

OIP may be 'Omnium International des Pétroles', a french company formed in 1911, though I can't find much more about it. Mikenorton (talk) 12:06, 12 August 2009 (UTC)

I would say spare fuel for the barrel. The tail can be unbolted and let down, then have a barrel rolled on. Then you could baulk the tail with a 4x4 and just back the tank up to close the tail. Once you get up close to the battle zone, you siphon out the fuel in the barrel. And if you have to store fuel outside the vehicle in battle conditions, well that's as far away as you can carry it from the people.

It does seem that the tail is for climbing embankments/trenches. On the chain, I got nuthin'. It could be used to tow a weight with ground pressure closer to human values to set off anti-personnel mines, indeed if that barrel was filled with sand, it would do quite well as a mine-finder. Franamax (talk) 12:03, 12 August 2009 (UTC)

How about shooting the fuel drum, and then shoot the crew when they bailed out of the tank? I doubt it would be tenable inside with all that petrol running down the back. But carrying spare fuel on the back would beat running out of fuel. Maybe they refueled when they arrived at the battlefield but left the tank behind when they assaulted the trenches. Edison (talk) 15:23, 12 August 2009 (UTC)

External fuel drums are not uncommon in tanks. You use the external tank to get from the friendly area to the combat area. Then, you discard the tank. Now, once in the combat area, you have a full tank of fuel and all those tanks who didn't have an external tank used up half their fuel to get to the combat area. There is very little risk of someone attacking the external tank since it is only used in friendly areas. As a side benefit, those with external tanks are allowed to expend nearly all their internal fuel during combat. All they need to do is leave the combat area and then a new external tank can be attached to get all the way back to the tank's unit. -- kainaw™ 15:28, 12 August 2009 (UTC)

If I recall, even some of the more modern Soviet tanks (T-72 perhaps?) used oil drums as external fuel tanks, with a switch to jettison the things if you found yourself in combat. Googlemeister (talk) 15:32, 12 August 2009 (UTC)

Correct. There was a T-72 on display when I was at 29 Palms. It had an external tank. I do not know of any modern American tanks that have external fuel capability. -- kainaw™ 15:34, 12 August 2009 (UTC)

It seems the M1 Abrams at least does (that article says "Another was put out of action in an incident when fuel stowed in an external rack was struck by heavy machine gun rounds") and this article gives the M1's range "with external tanks". -- Finlay McWalter • Talk 17:14, 12 August 2009 (UTC)

Even in a combat situation, it still seems preferable to have the majority of the fuel stored outside of the tank. If the fuel is hit, the tank might be stranded with limited range (only what is inside its internal tank); but the majority of the damage would be dissipated without destroying the tank and injuring its crew. Nimur (talk) 20:32, 12 August 2009 (UTC)

Even in a tank I am not sure that you want a barrel of volatiles to be a nice vulnerable target for explosive shells and even something like a heavy machine gun. Probably better that the fuel is not hit at all, and you refuel every 200 miles or so from your friendly supply units fuel trucks. Back in WW1, might have been a different story. Googlemeister (talk) 14:03, 13 August 2009 (UTC)

stringing power strips

When there is a shortage of outlets, and you have a lot of things to plug in, is there any danger in stringing together several power strips to meet the needs? --Halcatalyst (talk) 12:25, 12 August 2009 (UTC)

It depends on the circuitry you have in your house, and it's capabilities. At some point, for any circuitry, with enough things turned on and drawing current you are going to trip the circuit breaker, or fuse or whatever. When we first moved into our house a few years ago, we couldn't run the microwave and toaster at the same time without tripping the breaker for the kitchen, so we had someone re-do some of the electrical work. —Akrabbim^talk 12:35, 12 August 2009 (UTC)

So long as you don't exceed the current capacity of either the circuit or each strip, and assuming all the ground pins work and there's no bare wires or other problems, you should be fine. If you are plugging in a lot of varying loads or things you use all at once, you need to do some math to be sure you aren't causing an overload. Check the number of watts for each device, add them up and divide by a hundred. Compare that to the number of amps of the fuse or circuit breaker and you should be OK. For instance, if you have a 1200-watt heater and a 40-watt light, (1200+40)/100 = 12.4, which would be fine on a 15-amp circuiot. However, plugging all of your rock band's equipment into one string of power strips could be a bad idea. Franamax (talk) 12:42, 12 August 2009 (UTC)

Note that this calculation only works if you live in places with 115V mains voltage (eg the US). For 220V mains voltage, divide by 220. — QuantumEleven 14:22, 12 August 2009 (UTC)

Fire. It is always a bad idea to plug a power strip into another power strip and, although I suppose it depends on where you are, I would imagine in most places it's against the fire code. At least, I know it is in New York. If you really need more than 2x6 outlets, you should consider extension cords to other outlets nearby or getting extra ones installed for safety and legal reasons. ~ Amory (user • talk • contribs) 13:04, 12 August 2009 (UTC)

Out of curiosity, how does plugging several power strips into each other increase the risk of fire? — QuantumEleven 14:23, 12 August 2009 (UTC)

more plugs = more 'opportunities' for failure? 194.221.133.226 (talk) 15:10, 12 August 2009 (UTC)

It can cause Power quality problems due to the increased resistance in the ground path. I knew an audio/video recording studio which developed unacceptable hum (in the analog days) due to the high ground resistance from the connections of plugs when they octopussed the wiring via power strips. The problem went away when every piece of equipment was grounded to the same point and only hard wired outlets were used. Having many outlets fed from one outlet increases the risk of a fire, since the breaker might not work, the fuse might be oversized (30 amp fuse protecting a circuit rated at 15 amps), or there might be an oxidized high resistance connection in the wiring, or other problems.. Electrical safety codes were written in blood, so to speak. Edison (talk) 15:18, 12 August 2009 (UTC)

When I was about 5, i found where my parents kept all the double adapters, so i thought it would be fun to plug then all into the wall. I think I got to about 4 or 5 until i got a big shock. Learned that lesson the hard way. Vespine (talk) 02:05, 13 August 2009 (UTC)

The term de jour is Daisy chain (electrical engineering). --Tagishsimon (talk) 02:10, 13 August 2009 (UTC)

Transmission of swine flu

Is it that H1N1 flu may get transmitted into your body ONLY when you come in contact (about 6 feet close) with a suspected case of SWINE FLU ,or flying in the air it may enter inside?121.245.156.186 (talk) 14:57, 12 August 2009 (UTC)

I think, I may be wrong, that H1N1 cannot live on surfaces very long and that contact is the main way of spreading. Dogposter 15:14, 12 August 2009 (UTC)

"This is thought to occur in the same way as seasonal flu occurs in people, which is mainly person-to-person transmission through coughing or sneezing of people infected with the influenza virus. People may become infected by touching something with flu viruses on it and then touching their mouth or nose."[8] --98.217.14.211 (talk) 15:15, 12 August 2009 (UTC)

Our article on influenza says "The length of time the virus will persist on a surface varies, with the virus surviving for one to two days on hard, non-porous surfaces such as plastic or metal, for about fifteen minutes from dry paper tissues, and only five minutes on skin". Gandalf61 (talk) 15:17, 12 August 2009 (UTC)

It should also be reemphasized that H1N1 or "Swine flu" is entirely "typical" in terms of being a flu; it is not more contageous, more virulent, and does not cause worse symptoms than any other standard strain of Influenza A that come around every year. The only problem is that, as a relatively rare and new strain, we don't have the vaccines for it yet. But otherwise, it is just the flu. --Jayron32 01:39, 13 August 2009 (UTC)

Reliable source please? Stats at the 2009 flu pandemic article seem to indicate indicate higher mortality among the infected than typical seasonal flu. I suppose this could be the gap between the number actually infected and those going to a hospital or doctor and getting tested, but mild cases of seasonal flu also are likely to forgo doctor visits. As for transmissability, it continued to spread in the Northern Hemisphere countries through the summer when the seasonal flu drops off. It is not a matter of just not having the vaccines. Edison (talk) 03:20, 13 August 2009 (UTC)

It's not just lack of vaccines, it is lack of natural immunity. I've seen estimates that about a third of people will get swine flu over the next couple of years, a given strain of seasonal flu won't infect anywhere near that many people and that isn't because of vaccines - in the UK, at least, only vulnerable groups are vaccinated against seasonal flu. If you have had one strain of flu you will generally have some degree of immunity to other similar strains. I don't think there are any strains similar to swine flu in circulation, so very few people have any significant immunity to it. Of course, that doesn't change the fact that it is just flu and a few days bedrest will cure it in the vast majority of people. --Tango (talk) 02:52, 13 August 2009 (UTC)

And while right now it is "just the 'flu", the reason the World's epidemiologists are so worried is that studies of its genetic code reveal that it has far more potential than the average strain of 'flu to mutate into something (a) much more contagious and (b) much more deadly, as did the H1N1 Spanish 'flu of 1918, which it more closely resembles than most seasonal 'flues. 87.81.230.195 (talk) 03:44, 13 August 2009 (UTC)

I've heard that point before, but I've never heard any estimates of the likelihood of it happening. Do you know of any? I suspect (based on past experience with such news stories) it is extremely unlikely and is being sensationalised by the media. --Tango (talk) 17:12, 13 August 2009 (UTC)

The publicity about the importance of hand washing and use of hand sanitizers, and staying home when sick, may decrease the incidence of seasonal flu and common cold as a side effect. The swine flu seems to be killing a larger portion of infected healthy young adults and pregnant women that seasonal flu usually does. Edison (talk) 19:22, 13 August 2009 (UTC)

Bluetooth Marketting

What is meant by bluetooth marketting???where is it used???Need some details on it please.thanks. —Preceding unsigned comment added by Gd iitm (talk • contribs) 16:26, 12 August 2009 (UTC)

Check out Bluetooth marketing. Aaadddaaammm (talk) 16:47, 12 August 2009 (UTC)

It doesnt give the exact details on what is meant by bluetooth marketing and the software used in it.Pls help —Preceding unsigned comment added by 203.199.213.130 (talk) 18:28, 12 August 2009 (UTC)

Grantt Chart

hey friends,

wiki dosent contains anyting about grantt charts.i m facing some problems in understanding a problem on grantt chart. please help me how to understand it. a grantt plan with a 80% gurantee is used on a job that is 30% process controlled.The plan uses a standard hourly rate of Rs20 and a bonus rate of Rs 25 per hour.the standard time for this job is 0.1 hourper piece.determine earnings per day(8 hour) of work,if 85 pieces were produced on a given day.comment on merit of plan.

SCI-hunter (talk) 12-8-2009 —Preceding unsigned comment added by SCI-hunter (talk • contribs) 17:18, 12 August 2009 (UTC)

Do you mean Gantt charts? --TammyMoet (talk) 17:22, 12 August 2009 (UTC)

thanks for the link.but do help me to get through the question.. 218.248.11.212 (talk) —Preceding undated comment added 07:32, 13 August 2009 (UTC).

Wikipedia doesn't do your homework for you. I suggest looking at the notes you took during class. DJ Clayworth (talk) 19:18, 13 August 2009 (UTC)

How to cause hypomania

Are there any known methods for causing hypomania in oneself or a willing subject? NeonMerlin 17:39, 12 August 2009 (UTC)

This is not medical advice, but the symptoms sound a lot like someone who has done quite a bit of cocaine. --98.217.14.211 (talk) 18:13, 12 August 2009 (UTC)

"Induced Hypomania" is usually caused by anti-depressants. One similar situation where we get a similar profile of signs and symptoms would be a person who has just achieved something, be that passed an exam, completed a marathon etc. Fribbler (talk) 18:22, 12 August 2009 (UTC)

pluto

When does NASA expect to start sending back photos of pluto? How large of a window do they have to get good high res photos? Googlemeister (talk) 19:39, 12 August 2009 (UTC)

(ec) This should help with your answer - New Horizons#Planned. The probe will make a pass at 11:47 UTC, July 2015. It will be traveling at 13.78 km/s, or about 31,000 miles per hour, so the window is probably not very large, especially given it will be only 10,000 - 14,000 km away at that time and will flyby Charon, Hydra, and Nix within 15 minutes. They already have a picture, but it ain't exactly hi-res... File:112806_pluto_animation.gif. ~ Amory (user • talk • contribs) 20:25, 12 August 2009 (UTC)

I assume you're talking about the New Horizons mission. It arrives at Pluto on July 14, 2015. Based on the length of its encounter with Jupiter, I'd guess there's a two- to four-week window of good observations for the Pluto encounter. — Lomn 20:26, 12 August 2009 (UTC)

Ah, I see our article goes into much more detail at the Pluto flyby subsection. New Horizons will have greater resolution than Hubble for about three months. However, as for when NASA expects NH to start returning pictures of Pluto -- that first happened in 2006. — Lomn 20:28, 12 August 2009 (UTC)

The window will be small, however, you can take several hundred pictures within 30 minutes, right? And you aren't NASA. I say we'll have an awesome slide-show awaiting us when they release it. —Preceding unsigned comment added by Hubydane (talk • contribs) 19:51, 14 August 2009 (UTC)

Pain sensitive areas on human body

What are some surprisingly pain sensitive areas on the human body? My cuz told me if you took your finger and hook your perputrator in the mouth (outside the teeth) like a fish, it would be very painful for him. However I tried it on myself and its not that painful like a swift kick in the you-know-where for guys. --Reticuli88 (talk) 20:01, 12 August 2009 (UTC)

Perhaps you could read Pressure point. There are a few mentioned in that article. Googlemeister (talk) 20:13, 12 August 2009 (UTC)

Repeatedly twist a knuckle into the upper/mid sternum area (where the bone is near the surface) - or make a fist and rapidly rub your foreknuckles up and down the same area. Surprisingly painful. --Kurt Shaped Box (talk) 22:03, 12 August 2009 (UTC)

I really like going for the inner wrist or inner elbow. If someone's infringing on your space it's often with their arms; these are the two soft, nerve-y points that are thereby exposed. You squeeze, they feel pain, you release, they are fine. No lasting damage. Vranak (talk) 04:23, 13 August 2009 (UTC)

You physically assault people who get too close to you?? Exxolon (talk) 00:39, 14 August 2009 (UTC)

I have done so in the past, yes, but only with my brother. Vranak (talk) 16:36, 15 August 2009 (UTC)

If someone assaults you, simply punch as hard as you can directly on their clavicle (collar bone). It's an easy bone to break, but surprisingly painful. Other painful places: 1. Gonads 2. Ribs 3. The inner thigh, close to the gonads 4. Kick 'em in the knee. 5. If you place your finger on the back of you lower jaw (close to your earlobe) then move 1/2 in - 1 in toward the chin. Move your finger toward your throat. There is a gland there, and I guarantee that if you poke anyone there hard enough, you win. Hubydane (talk) 19:56, 14 August 2009 (UTC)

Punching someone in the solar plexus (just below the sternum) really hurts too, and also "takes the wind" out of the assailant (which would put you at an advantage in the fight, or give you time to escape). An uppercut to the jaw would work too, but you gotta be quick with the punch. FWIW 98.234.126.251 (talk) 03:41, 16 August 2009 (UTC)

Fat joe

Would it be possible to 'brew' coffee in a fat (for instance olive oil or clarified butter) rather than in water? Is this ever done for culinary purposes? If the boiling point of olive oil is so much higher than that of water, it seems to me that it would be a better substrate for coffee, because the grounds would rech a higher temperature without burning. I would prepare it in a pan, as if I were making a roux, and keeping the temperature a bit below 100 C. Then I would strain the oil to remove the grounds. Having produced coffee oil (or coffee butter), I can't think of what use it might be put to. I guess you could use it as a flavoring, or allow the butter to cool and use it as a spread. Would it be fully caffeinated? LANTZY^TALK 20:07, 12 August 2009 (UTC)

It will probably wreck the plumbing of your coffee machine if it is a drip or percolator design. Also, these machines need to heat the liquid up to steam; I don't know if oil will vaporize in a way that will flow through the plumbing. Maybe an all-passive device such as a Moka pot (not a mocha pot!) would be a better maker for your purposes. I'd still worry about gumming up the fluid paths with oily residue; it will be tough to clean and your future coffee will taste weird until you get rid of the residue. The coffee flavors, including the caffeine, are present in the fat/oil of the coffee bean, so they should dissolve nicely if you can get hot oil to flow over them. However, most culinary uses will just grind the coffee very very finely (finer than espresso) and mix it directly into a cake-batter or other food item. Nimur (talk) 20:37, 12 August 2009 (UTC)

I wouldn't be using a coffee maker or any such device. To quote myself, "I would prepare it in a pan, as if I were making a roux." LANTZY^TALK 22:39, 12 August 2009 (UTC)

My apologies for asking a question within a question, but it seemed relevant so I thought I'd go ahead: would the nature of the solvent used to do the brewing (i.e. polar/non-polar) be important? Basically, would 'brewing' coffee in oil cause the caffeine (and other chemicals) in a standard cup of coffee to be extracted from the bean in the same way (or even at all) that using water would? If so, how does the extraction proceed chemically? Korokke (talk) 21:59, 12 August 2009 (UTC)

Indeed, this is the kernel of my question. I am curious about the chemistry here. LANTZY^TALK 22:39, 12 August 2009 (UTC)

Water, being a semi-polar, semi-nonpolar solvent, works well at extracting coffee oils, and caffeine. Water laced with carbon dioxide is even better at pulling the caffeine out; this is called "decaffeination" and it works by a combination of physical and chemical solution (you probably cannot get a supercritical fluid in a frying pan - not even a pressure cooker). This 1972 patent suggests several edible esters which are "more effective". Oil will probably also dissolve the caffeine and other oils in the grounds. This report suggests some solvents will override the flavor of the coffee. This report suggests a water + oil + emulsifier mixture as even better than oil. Nimur (talk) 22:45, 12 August 2009 (UTC)

What about a mixture of water and hot ethanol? Then evaporate the ethanol off if you don't want an alcoholic drink. It also depends whether the caffeine is protonated or not -- I imagine that in the presence of tannins, a lot of the caffeine will be in protonated form and therefore would not like to bind with nonpolar solvents. John Riemann Soong (talk) 13:19, 13 August 2009 (UTC)

Thanks for the comments, everyone. LANTZY^TALK 02:22, 15 August 2009 (UTC)

polar day animals

During the polar day, how do animals know when to sleep? —Preceding unsigned comment added by 213.46.83.5 (talk) 21:54, 12 August 2009 (UTC)

When they are tired? There's no reason for conventional circadian rhythm. "Hours" are a human invention; they have no real basis in nature, except that in some regions, they map well to an astronomical cycle; in polar regions, animals are adapted to the day-night cycle that they experience. Nimur (talk) 22:40, 12 August 2009 (UTC)

Other than right exactly at the poles, there are always daily fluctuations in light levels, even if there is some light through the entire day -- the fluctuations grow larger the farther you move from the poles. I don't remember seeing any research specifically about polar animals, but it seems likely that they have heightened sensitivity to small fluctuations. ("Hours" may be a human invention, but 24-hour-ish circadian rhythms are built deeply into animal biology -- the genes that drive them in fruit flies have a strong resemblance to the genes that drive them in mammals.) Looie496 (talk) 22:57, 12 August 2009 (UTC)

That is interesting, because 200 MYA, the day was only 23 standard hours. I wonder if really really old species might have had biology for say a 20 hour day. Googlemeister (talk) 13:55, 13 August 2009 (UTC)

Even at the poles, there is variation - the earth's rotational axis is tilted remember. SteveBaker (talk) 02:48, 13 August 2009 (UTC)

At the poles, the sun appears to rotate around the observer but stays the same distance above the horizon for the whole day. As you move away from the poles, it starts to shift up and down as well as appearing to rotate. Looie496 (talk) 15:43, 13 August 2009 (UTC)

There is seasonal variation, there isn't daily variation (unless the sun is fairly low and goes behind hills at some times during the day). --Tango (talk) 23:29, 13 August 2009 (UTC)

X-rays

I just watched a programme on TV with airport border officials placing metal tubes through an X-ray scanning machine to check the internal contents. To me, these tubes appeared shiny, and thus light must have been reflected off the smooth surface of the tube (a property which makes metals appear shiny, right?) If X-rays are merely photons of a different wavelength to that of visible light, wouldn't they be reflected too, and thus the internal contents of the tube would not be visible since the photons would be reflected away from the surface? Even so, they did manage to view the contents, so how is this possible?

Regards, --—Cyclonenim | Chat  22:50, 12 August 2009 (UTC)

Different wavelength of photons are absorbed by different materials. In order for a photon to be absorbed (and, in the case of a mirror, re-remitted), there has to be an electron that can use the photons energy to change to a different energy state. In individual atoms and non-conducting crystals, there are only discrete levels of energy an electron can have, and only photons that correspond to the change in energy between two such states can be absorbed or emitted. Metals are very good conductors and very shiny because their electrons are not in discrete orbitals, but merge into energy bands. Thus, for a photon with an energy that is much smaller than the widths of those bands, there will normally be an electron ready to absorb it. As the energy goes up, the chance to find a photon that can absorb the energy while staying in a given band goes down. X-ray photons are energetic enough that absorption is a relatively rare event, hence they can pass through many substances quite well. --Stephan Schulz (talk) 23:36, 12 August 2009 (UTC)

I would like to point out that even though the answer above is essentially correct, it makes the fairly commom mistake of stating that reflected photons are absorbed and re-emitted. Reflected photons are never absorbed, they are reflected. Dauto (talk) 00:02, 14 August 2009 (UTC)

For more information, see the transmittance, absorbance and reflectivity articles, which mention how all those optical properties depend on the incident photon’s wavelength (or frequency), and electronic band structure and band gap for more detailed information about the quantum mechanical properties of a solid that result in those optic properties. Red Act (talk) 23:58, 12 August 2009 (UTC)

It's not hard to visualise: Imagine a piece of red tinted glass. You hold it up to the light - white light heads into the glass - only red light comes out. All of the other colors are absorbed or reflected. It's the same deal with your container - it lets "x-ray light" through and absorbs or reflects all of the "visible colors". SteveBaker (talk) 02:46, 13 August 2009 (UTC)

Goumi (Elaeagnus multiflora)

What is the highest daytime temperature that Elaeagnus multiflora can tolerate? Thanks in advance, --Dr Dima (talk) 23:45, 12 August 2009 (UTC)

Global warming

News always say global warming but we don't notice this much greenhouse gas. In Los Angeles-orange county climate changes hasn't been affect too much. Antartica, Greenland, and Artic Circle places haven't been affect too much. The winter is getting colder. In Miami, last winter got as cold as 30 F enough to freeze an orange solid rock. How is global warming affecting the climate changes? The place my 10th grade english teacher grew up in New Jersey start snow in late October then melt in April.--69.229.108.245 (talk) 23:55, 12 August 2009 (UTC)

Of course we "notice" the increase in greenhouse gases - see Keeling curve. Greenland and the Arctic have been warming up very significantly, as has most of the rest of the globe. See this graphic. Climate trends are long-term - typically measured over 30 years or more, looking at one year or the other is insignificant. Have you read global warming and instrumental temperature record? --Stephan Schulz (talk) 00:31, 13 August 2009 (UTC)

The Arctic circle not affected too much? The Arctic ice has been repeatedly setting records in recent years for how little ice it gets down to in the summer, and it’s expected to be completely ice-free during the summer within a matter of years, something that hasn’t happened in the last 700,000 years. It’s a very rare thing going on in the Arctic. See Arctic shrinkage. Red Act (talk) 01:09, 13 August 2009 (UTC)

Your teacher, just like many, many people, is using their personal experience to make a judgment about whether global warming is real. Personal experience, unfortunately, is anecdotal evidence and is worth, basically, nothing, because they are using very few data points and reliance on human memory (as in, "Feels cold today. Hm."). Confirmation bias unfortunately results. Reading the scientific reports would be more valuable. Tempshill (talk) 01:53, 13 August 2009 (UTC)

It's "global" warming - and "climate" change. It's not necessarily "local" warming or "weather" change. The distinction is crucial. On the average, the entire planet is getting warmer. That doesn't mean that some places won't get cooler - that's perfectly possible. The climate is changing - that's a long-term thing...the short term weather may change - or it may not. Some places in the world may get much warmer than the average - other places, not so much.

For example, here in Texas, summer days vary from about 90 degrees (F) to about 110 degrees F. The "weather" can vary by about 20 degrees from day to day through the summer. But the average temperature of the planet has only increased by a few degrees. Let's say it's 3 degrees of average global increase: So, sitting here in Texas, watching the thermometer, we might start seeing extreme 113 degree days - breaking the occasional record - and we might find that there are no more 90 degree days - with the temperature only ever getting down to 93. But most of the time, the temperature goes up and down - if it's 105 today, does that prove there is global warming? Not really...105 degree days have always been here.

You have to look at the big picture. That glaciers are retreating all around the world. That the ice at the north pole is vanishing at an alarming rate - that the south polar ice is breaking up - that plants and animals that are normally seen close to the equator are becoming more common further from the equator. That cold-loving plants are becoming harder to find in low lying areas and you can increasingly only find them higher up on mountain slopes. Trust me, this is very real - but that doesn't mean that all of a sudden you're going to get really, really hot weather every day...that's just not how it works. SteveBaker (talk) 02:40, 13 August 2009 (UTC)

Yes, having 3 exceptionally cold winters and cool summers in a row where I am does not prove that global warming is not happening, because this area is not the entire globe. Googlemeister (talk) 13:49, 13 August 2009 (UTC)

As I pointed out above, the "entire planet" probably is not getting warmer. The average surface temperature is rising, or the average ocean surface temperature - because the climate and atmospheric interactions are redistributing energy in a different way - very probably due to the chemical changes that human industrial activity has unleashed into the atmosphere (notably, carbon, but also water vapor, CFCs, and other things that are less well understood). For the planet to actually warm, there would need to be a change in the incident solar radiation. The issue is more properly called "global climate change" than "global warming" - even when the most significant worries are warmer summers and melting polar ice caps. There is a really huge ambiguity when people talk about the "temperature of earth" - and they should use more precise terminology to avoid confusion. When the earth's surface (where we live) raises temperature, that energy has to come from somewhere - either the high atmosphere must cool, or the solar radiation must have increased; or some similar planetary-scale energy exchange; but extra heat energy does not just appear from nowhere because our atmospheric composition has subtly changed. Nimur (talk) 15:53, 13 August 2009 (UTC)

Um what? I would say it's accurate to say the entire planet is getting warmer. You missed out a key point. The greenhouse effect means that without a change in incident solar radiation you can get a warmer planet, as less of the heat escapes. See also radiative forcing. I think it's mostly accurate to say Venus is quite a different temperature from Titan for reasons beyond the difference in incident solar radiation. As far as I'm aware a significant part of the energy we're referring to escapes to regions of space long beyond what we would normally call our atmosphere so I don't think it's accurate to say where just talking about a redistributions of heat from the high atmosphere to the low atmosphere and surface. P.S. This explaination is probably a little too simplistic and I'd welcome any improvements. I do agree more careful use of terminology may be wise. Nil Einne (talk) 18:39, 13 August 2009 (UTC)

And another nitpick, Nil Einne - with all due respect, you are doing exactly what I was talking about, with regard to Venus. You are conflating its surface temperature with its planetary temperature - when in fact, Venus' planetary temperature is lower than it should be, based on its proximity to the sun. Go explain that with the greenhouse effect! The surface temperature is extremely high - enough to melt lead - but the planet temperature is about 50 kelvins below the expected (Fraknoi et. al), NASA fact sheet. Nimur (talk) 19:43, 13 August 2009 (UTC)

A hotter planet radiates energy faster - not just faster, A LOT FASTER, with tiny perturbations resulting in huge radiative cooling changes - , via radiational cooling. As far as I am aware, no such change in the blackbody spectrum of Earth has been observed, ever. When we see a hotter ocean, it means that somewhere else, something is cooling faster to dissipate that energy - take a look at this 2003 NASA news brief - ""Extreme cold is required to form ice in a dry environment like the mesosphere," says Thomas. Ironically, global warming helps. While greenhouse gases warm Earth's surface, they actually lower temperatures in the high atmosphere. " (To be fair, this statement and many like it were the subject of fierce academic debate, and appeared in an EOS journal release which I am currently looking for...) Nimur (talk) 19:32, 13 August 2009 (UTC)

Found it - Are Noctilucent Clouds Truly a "Miner's Canary" for Global Change? - EOS vol. 84, #28, July 2003. Nimur (talk) 19:36, 13 August 2009 (UTC)

Your premise that incident solar radiation needs to change (presumably increase) for the planet to get warmer is false. --98.114.98.16 (talk) 17:08, 15 August 2009 (UTC)

Sez who? You got any proof of that? 98.234.126.251 (talk) 06:33, 16 August 2009 (UTC)

Nimur is probably right in saying that the "entire planet" isn't getting warmer...including the whole body of the planet rather than just the surface, oceans and atmosphere that is. However, that's really something of a nit-pick. To all of us humans, the plants and animals and everything else we care about - the temperature of the top couple of feet of soil, the water and the air are really all we care about. The temperature of all of the things we care about is increasing - and that's what matters. Use of the word "global" is commonly taken to mean "just the surface stuff". When we talk about a "global flu pandemic" - we don't seriously imagine that there is a flu outbreak at the center of the earth. When we say there is a "global recession" - we don't mean that there are banks going out of business at the center of the earth. So "global warming" is a perfectly cromulant term...live with it! SteveBaker (talk) 00:26, 14 August 2009 (UTC)

It's not only about terminology - it's instructive and helps conceptualize the problem when you realize that what is actually happening is a redistribution of the energy in our atmosphere, and the consequences that follow are changes in weather patterns. Nimur (talk) 14:32, 14 August 2009 (UTC)