Wikipedia:Reference desk/Archives/Science/2010 November 12

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November 12

Goosestepping: North Korea versus the Wehrmacht

CBS TV today showed a profile of the current state of North Korea. They showed the version of goosestepping employed by both the North Korean army and young girls of that country marching. In both cases, as they marched their heads moved up and down more sharply than in WW1 or WW2 films of the German army goosestepping. The NK soldiers hats almost fly off on each step. How does the standard NK goosestep differ from the Nazi 20th century German goosestep? What is the advantage of marching thus versus the march step of present day US, British,or German troops? Does goose-stepping cause the hip injuries and muscle strains that it would seem likely to cause? Do Goosesteppers actually march that way when they have to get 20 miles from Point A to Point B in a war? Edison (talk) 01:16, 12 November 2010 (UTC)

See Goose-step. It's for ceremonial purposes. Dismas|^(talk) 01:39, 12 November 2010 (UTC)

On a side note, and unrelated to the science of the question, the Wehrmacht were the normal German army during WW2, and one did not necessarily have to be a Nazi to be in the Wehrmacht. Towards the end of the war, the only requirement to be in the Wehrmacht was being alive. You are probably thinking of the Schutzstaffel, or SS. --KägeTorä - (影虎) (TALK) 01:45, 12 November 2010 (UTC)

Movies from WW1 showed the Kaiser reviewing soldiers who were clearly goosestepping. There were no SS then. But they marched with less up and down snap than the North Koreans, the observation key to the original question. Do the NKs go up on tiptoe with each step while the Germans marched flat footed, or what? As for it being a ceremonial step used in review, did WW2 Germans marching from town to town march the same as Allied soldiers, and what commands were given to start them/stop them marching like geese? It would seem likely to have an attendant cost in soldiers unfit for duty due to injuries of the hip or knee. Edison (talk) 06:01, 12 November 2010 (UTC)

Yes, I know that well enough. As the article on Goose-step says, it was a Prussian invention. I was referring to you implying that the Wehrmacht were the same as the Nazis - which I see has been corrected in the original post. --KägeTorä - (影虎) (TALK) 13:03, 12 November 2010 (UTC)

Do geese really walk that way? If not, why the name? HiLo48 (talk) 06:14, 12 November 2010 (UTC)

See the NK at 1:00 in this Youtube: [1]. They bounce more than the WW2 Germans victory march in Paris in 1940, at 0:25 and following:[2], though the SS does bounce a bit in this :[3], but still less than the NK marchers. (The Rockettes bounce even more than the NK forces, while doing a similar step (at 0:25):[4])Edison (talk) 06:27, 12 November 2010 (UTC)

Look at the way British Military marches during Trooping the Colour they would get no 20 km in that way. Both ways to march were and are 100% for ceremonial use. The GDR army was marching that way till their end in 1990. In German the whole thing is called Stech-schritt Stab-step sounding more dangerous than goose. --Stone (talk) 06:33, 12 November 2010 (UTC)

@ HiLo, well sort of [5], but the effect with the goose seems to be caused by the upper part of the leg is hidden thus giving a sort of strutting gait. This is emulated in human marching by keeping the whole leg stiff - Hmm, that's a bit obvious. Richard Avery (talk) 09:54, 12 November 2010 (UTC)

Just to say that the German Army abandoned the goosestep at the start of WWIIafter 1940. The Soviets used it following the Imperial Russian tradition (Peter the Great copied it from the Prussians). The North Koreans have taken it from the Soviets (maybe via China?[6]). The Russian Army still uses it too[7]. BTW the British Army quick march[8] is certainly a very efficient way of moving troops from A to B (hardly changed since the 18th Century according to this[9]) - the slow march[10] is purely ceremonial. Alansplodge (talk) 13:16, 12 November 2010 (UTC)

The quick march used by British light infantry and rifle regiments is even more efficient[11]. Alansplodge (talk) 17:56, 12 November 2010 (UTC)

If you want to see some really extreme ceremonial marching, find some footage of the Wagah border ceremony, whose more spectacular elements were reportedly curtailed only last month. Oh, here's some. 87.81.230.195 (talk) 22:11, 12 November 2010 (UTC)

Here are real geese stepping, at 0:55 :[12]. Here is an animated Donald Duck goose-stepping, at 3:45, bobbing up and down about as much as the North Koreans: [13]. Still no answer as to why the NK folks heads snap up and down as they execute the goose step to a greater extent than any previous fascist troops, so that soldiers' hats almost fly off. Is it a faster cadence, or something different in the execution of the step? Was there ever a problem with goose-steppers kicking the butt of the soldier in front? Edison (talk) 00:55, 13 November 2010 (UTC)

Are you sure the head movement is not simply an intentional part of the march? Nil Einne (talk) 18:07, 13 November 2010 (UTC)

Just an FYI from my personal experience, East German soldiers still goose-stepped for ceremonial purposes as late as 1987. thx1138 (talk) 00:52, 13 November 2010 (UTC)

The above linked article does mention they abandoned it during reunification so that seems likely Nil Einne (talk) 17:41, 13 November 2010 (UTC)

Are peanuts bad?

More importantly, are they this bad? [14] Thanks. Imagine Reason (talk) 02:40, 12 November 2010 (UTC)

Maybe. The listed info is not of high quality. The reference supplied points to a letter to the editor[15], not a study. This letter in turn references a study[16] but that study is comparing peanut oil to olive oil, it's not trying to find out if peanut oil is bad. Tree nuts do have many health benefits, but peanuts don't. I wouldn't go so far as to say ban them as unhealthy, but I would say don't try to gain any health benefits from them, and eat them like you would other so-so foods. Ariel. (talk) 04:11, 12 November 2010 (UTC)

Peanut oil does have its benefits, however. It has a very high smoke point which allows foods to be fried at a higher temperature; higher temperature frying results in higher outward pressure of water as it leaves the food, which coincidentally results in less oil getting into the food, resulting in a crisper fried product with less oil in it; thus foods fried in peanut oil can be lower fat than those fried in other oils. --Jayron32 04:28, 12 November 2010 (UTC)

(edit conflict with Jayron) The Atherogenenicity of Peanut Oil has been well established for quite some time (since the 1970s, at least: [17] and [18]). It is said to produce "fibrous", rather than "fatty" lessions; I'm not sure if that makes any difference in terms of heart disease. So yes, peanut oil is worse for clogging the arteries than most other unsaturated fats. Is it worse than saturated fats? The 1971 report showed coconut oil (high in saturated fat) and peanut oil having similar effects. So no, peanuts aren't going to be as healthy as tree nuts. You should probably treat them more on par with red meat than walnuts. Few would say that beef is unhealthy in moderate amounts, but eating too much can cause heart problems. Buddy431 (talk) 04:38, 12 November 2010 (UTC)

It's really tough to top Christopher Columbus for shear evil. In addition to all the kids with peanut allergies, you've got the worldwide Tobacco diseases, the Great Famine (Ireland) and High-fructose corn syrup. Hcobb (talk) 04:46, 12 November 2010 (UTC)

According to the peanut article, the FDA in 2003 released a statement that "Scientific evidence suggests, but does not prove, that eating 1.5 ounces per day of most nuts, including peanuts as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." Of course, that was under George W. Bush, and one might suspect that America's fiduciary duty to recommend domestically grown products would have been morally superior to any potential health science data... Wnt (talk) 09:39, 12 November 2010 (UTC)

Much as I hate George W. Bush, this particular attitude is not something you can pin on him. Favoring domestic food producers with powerful lobbying groups, even at the expense of science, is a non-partisan issue in US politics - everybody does it. thx1138 (talk) 00:54, 13 November 2010 (UTC)

This[19] 2005 research doesn't make them sound too bad. Alansplodge (talk) 13:09, 12 November 2010 (UTC)

Antioxidants are overrated, I think. Antioxidant supplements are worse. Imagine Reason (talk) 00:26, 13 November 2010 (UTC)

I have to agree that "antioxidant" is an overused buzzword in terms of health. It is a real chemical activity, yes, but biological systems don't work like beakers in a laboratory — you never really know the effect that something will have until that exact compound is tested. For comparison consider enantiomers, which always have the same basic chemical properties, but often have completely different effects in the body. Wnt (talk) 18:45, 13 November 2010 (UTC)

why is AC more dangerous than DC?

Normalising for voltage and current, etc. is it because the peak voltage of AC is higher than the average voltage? Does the body adapt less well to an alternating current and is more likely to send ion channels out of whack? John Riemann Soong (talk) 05:21, 12 November 2010 (UTC)

I thought it was because if you grabbed a live AC wire it would force your muscles rigid and you wouldn't be able to break free, whereas a DC wire would have the opposite effect - such that the consequences of shock are VERY different in severity depending on current type. 59.46.38.107 (talk) 05:25, 12 November 2010 (UTC)

Alternating current also has a frequency (50-60 Hz, depending on location) which can cause Ventricular fibrillation Higher frequency may avoid this problem, but as frequency increases, efficiency decreases, so that's a problem for transmission as well. War of Currents covers some of these differences, and it has a reference for the heart trouble issue. However, safety aside, DC power transmission has serious problems with long-distance losses. Because of this, DC power transmission systems tended to be smaller in scale (each neighborhood or sizable factory would have needed its own dedicated power plant), which has serious problems in terms of expense and feasibility. AC power experiences much lower losses, it also reacts better to step-up and step-down transforming, so you can transmit long distances at MUCH higher voltages than you can at DC power, which only adds to the difference in efficiency. --Jayron32 05:37, 12 November 2010 (UTC)

At the same voltage and current, AC and DC should have similar voltage drops at the same distance of transmission, AC is easily stepped up via transformers for more distant transmission with lower "copper losses." I do not agree with 59.46.38.107's statement that DC makes you let go of a live wire. The "war of the current" tests generally showed greater lethality for AC than for DC at a given distribution voltage. Quite a low voltage might be lethal for some people, so do not experiment at home. The real difference was that AC was carried on overhead wires at 4kv or whatever, while DC was carried at a much lower voltage, initially 110 volts or so in the US. The problem was that only dense central cities like New York or Chicago or London could support a DC central station every couple of miles, whereas with AC a power plant could send out high voltage for many more miles economically, to be stepped down to 120/240 or so by transformers wherever there was a customer or a load center. Ironically, for very long distance transmission, DC is now popular, at 500 kilovolts or so. Of course it would be quite lethal to contact it at those high voltages. Edison (talk) 06:15, 12 November 2010 (UTC)

I also do not agree with 59.46.38.107 - it's actually the opposite of that. AC has zero crossings which enables you to let go, but DC does not, and will hold the muscles rigid. Ariel. (talk) 06:45, 12 November 2010 (UTC)

For example: [20] Quote: "Direct current (DC) is more likely to cause muscle tetanus than alternating current (AC), making DC more likely to "freeze" a victim in a shock scenario. However, AC is more likely to cause a victim's heart to fibrillate, which is a more dangerous condition for the victim after the shocking current has been halted."

However, that said you also have "Low-frequency AC produces extended muscle contraction (tetany), which may freeze the hand to the current's source, prolonging exposure. DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current's source." - which doesn't contradict the above, it just says the shock will move the hand, then freeze it, instead of freezing it in the original place.

On top of all that you also have an interesting table showing that 60hz AC requires less current than DC to cause trouble. Interestingly higher frequency AC is about the same as DC.

Final conclusion: Both AC and DC have hazards, but the hazards are different. Sometimes AC wins, sometimes DC, and there is no clear "better". Ariel. (talk) 10:41, 12 November 2010 (UTC)

It seems to me that whichever kind of power people want to tell you to stay away from, they say that that kind is more dangerous. --Anonymous, 23:18 UTC, November 12, 2010.

Another discussion on the same subject here[21]. Ignore my input - talking rubbish again! Alansplodge (talk) 11:57, 12 November 2010 (UTC)

Here is a good reference about electrical injuries. I removed the my citation required comment because Ariel has provided one. Cuddlyable3 (talk) 14:34, 12 November 2010 (UTC)

The "zero crossings" of AC occur 120 times per second (US),(110 per second, many other countries), so inertia would prevent much movement of the hand away from the wire before the next peak caused another strong contraction. Edison (talk) 17:55, 12 November 2010 (UTC)

You mean 120 and 100, of course. --Anonymous, 23:18 UTC, November 12, 2010.

You are right if it is 50 rather than 55 cycles in the non-US world. I forget sometimes. There was also 25 cycles and several other frequencies in the past. Edison (talk) 00:44, 13 November 2010 (UTC)

I just tried out holding the probes of a multimeter hard and the lowest I could get was about 1.3 megohms, I had to get things quite wet to get down to 250 kohms, that would only pass one milliamp at 250 volts. I can see it could get to be quite appreciable if my hands were actually in water but I'm a bit surprised that just one milliamp can have such an effect as people describe from touching a wire. The body must be very sensitive to low currents. Dmcq (talk) 01:09, 14 November 2010 (UTC)

The resistance of the body can drop quite dramatically after a certain voltage is surpassed. Part of this is that the conductivity of the skin is regulated by how open the pores are, and cells have membrane potentials, and changing their membrane potentials will affect their conductivity. If you get shocked quite a bit, your skin will open up its pores due to stress, which will decrease the resistance of your skin even further. John Riemann Soong (talk) 01:29, 14 November 2010 (UTC)

Cat swallow food when upside down

Is it true that cats can't swallow food upside down, and they rely on gravity for it to fall down their throat? They "bolt" food instead of swallow it? I've heard this for ages, but I can't find a single mention of it when searching, so now I'm wondering if I was mislead. Ariel. (talk) 07:32, 12 November 2010 (UTC)

This article specifically mentions peristalsis of the feline esophagus as a normal function [22]. I would think that peristalsis indicates a 'true swallow', and does not require gravity. SemanticMantis (talk) 15:14, 12 November 2010 (UTC)

I know this doesn't answer your question but it was in the news recently and is very much related, so I thought I'd pass it on. The physics of cats drinking water. Dismas|^(talk) 16:50, 12 November 2010 (UTC)

Compared with the dog, and this will amaze yuh! [23] Richard Avery (talk) 18:44, 12 November 2010 (UTC)

They kept saying how the cat is drinking better or smarter or something than the dog, but that video shows the dog doing the exact same "lift" a column of water and close jaws around it that the cat does! Only the dog also make a spoon of sorts with his tongue. So it seems to me that cats are not unique in this. Ariel. (talk) 20:32, 12 November 2010 (UTC)

Ptosis in traditional cultures

There's some very good news (for women and men...) in our article on the brassiere — namely, that the bra does absolutely nothing to prevent ptosis (sagging), and perhaps is even counterproductive. It should be shouted from the rooftops... But it does leave me wondering: it is not at all uncommon when looking at film from various scantily clad 'indigenous' societies, to see women who have indeed developed ptosis to a truly remarkable degree. What is the reason for that? Wnt (talk) 09:08, 12 November 2010 (UTC)

The article on Ptosis_(breasts) offers scant information beyond the obvious that the fascia, skin and suspensory ligaments generally become more lax with age. The observation about 'indigenous' ladies is spurious as a large majority of ladies demonstrate the same effect, we just don't see so many UK indigenous ladies in such a state of undress. Richard Avery (talk) 09:36, 12 November 2010 (UTC)

Pregnancy is also a factor, so women in societies where the childbearing age is relatively early are likely to have a greater degree of ptosis than women of the same age in, say, the UK. Physchim62 (talk) 18:57, 12 November 2010 (UTC)

Ah, yes I see what you mean [24]. Caesar's Daddy (talk) 19:43, 12 November 2010 (UTC)

OK, Canada then (mean age of women at first childbirth: 29.9 years [25]) rather than the UK (29.1 years). Physchim62 (talk) 19:51, 12 November 2010 (UTC)

OK, I concede, ;-)) Global_incidence_of_teenage_pregnancy tells us that about 40% of the women in Niger have had a baby by the time they are 18. How tragic is that?! I guess that also meets the OP's 'indigenous societies' qualification. Caesar's Daddy (talk) 20:24, 12 November 2010 (UTC)

I don't see how something that happens naturally like having children under the age of 18 is tragic. It is not socially encouraged in Western culture, but that is really just an invention of the last century there too. Googlemeister (talk) 20:40, 12 November 2010 (UTC)

@ Googlemeister, so how many 18 year olds are in a position to give a baby a start in life, in the UK or Canada, let alone in Niger. The invention of which you speak is called health and social development. Just because it is 'natural' doesn't make it the best option. Richard Avery (talk) 10:26, 13 November 2010 (UTC)

aDMISSION into XLRI

I didnt complete my Btech yet because I still have 3 backlogs even after completing my 4rth year. I applied for XAT 2011 because I will anyway get my final memo by end of january 2011. When should I actually apply for admission into XLRI??? Should I do it now itself or after I get my XAT score card?? My aggregate is very less at present......will it affect my admission??? After I write my supplementaries I will achieve 57% as my aggregate.......will it be okay??? —Preceding unsigned comment added by 115.109.194.75 (talk) 12:44, 12 November 2010 (UTC)

Sorry, but we can't give advice to people. --The High Fin Sperm Whale 19:19, 12 November 2010 (UTC)

Sure we can- we give advice all the time to people. I can't give advice because I have no idea what OP is talking about. Staecker (talk) 01:54, 13 November 2010 (UTC)

I don't think it's that hard to get the gist of what the OP is asking about. It's true without knowing the details no specific answer can be provided but on the other hand, it's also true the OP would be much better of talking a careers or some other advisor at their tertiary institution and/or the people who run the XAT/XLRI [26] Nil Einne (talk) 18:33, 13 November 2010 (UTC)

Limits of Gene Therapy?

With the advances being made in using our own skin cells and turning them into stem cells, in the future would it be possible to say for example they found the gene for diabetes and they changed some cells to not include diabetes or cancer, would you be able if they put into a person enough stem cells without those genes could it then replace all the other cells in the body from those stem cells that multiply and replace all the other cells in the body? Is that even possible or are the newly injected stem cells only limited to certain areas in the body? How does or would that work? —Preceding unsigned comment added by 71.137.241.60 (talk) 15:27, 12 November 2010 (UTC)

This is a rather complicated question because you are asking about several big "if"s.

• First, it is true that scientists can reprogram stem cells to resemble a mature cell type, but it should be recognized that the resulting "re-programmed" cells are not exactly the same as if they developed according the normal developmental programs. There's a lot we don't know about possible tumorigenicity of reprogrammed cells.
• Second, not all organs of the body are amenable to simply injecting a whole bunch of stem cells in and hoping that they somehow replace the normal tissue architecture. One exception is blood cells, which are produced in the bone marrow and might be particularly amenable to replacement by stem cells (that's what a bone marrow transplant is, after all). However, most tissues of the body are highly organized in terms of blood vasculature, nerve innervation, and connections between cells. Some researchers think we might be better off growing new tissues in the lab (tissue engineering) and then transplanting them the same way we might with a donated organ.
• Third, diabetes and cancer are multifactorial conditions. For most common diseases, there isn't a single gene that can be removed or replaced with gene therapy "to not include diabetes or cancer". This is a much too simplistic concept of disease and in reality human diseases are much more complex. Only in very rare families do these types of conditions act as a heritable "single gene" disorder. Type 2 diabetes is really a problem with insulin resistance meaning that the peripheral tissues become insensitive to insulin, resulting in increasing requirement for insulin production by the pancreas and eventually the pancreas failing to meet the insulin demand. This is different than type 1 diabetes, where the pancreatic islet cells are typically destroyed by an autoimmune process. These two distinct forms of diabetes have different degrees of genetic contribution and would require different approaches in terms of a "stem cell replacement" strategy. Sporadic cancers (the vast majority of cancers) occur through a highly complicated multi-step process that usually entails lifelong exposure to carcinogens and chance somatic mutations. This simply is not amenable to a gene therapy treatment.

To sum up, gene therapy and regenerative medicine are really just in their infancy and there's way too much hyperbole in terms of what we can expect these treatments to be able to do. --- Medical geneticist (talk) 21:26, 12 November 2010 (UTC)

Technically, stem cell therapy need not be gene therapy. Cell types are established by a combination of epigenetic modification of genes, active feedback from existing patterns of transcription factor and other regulatory gene expression, and environmental cues. Culturing a cell type under just the right circumstances, with the right drugs, can occasionally lead to transdifferentiation without the need to change it genetically, though certainly gene therapy can be used to give cells a stronger hint about what you want them to do. In concept, it is conceivable that the right drug, perhaps a drink from a certain fountain or the fruit of a rare tree from Eden, could lead certain cells to take on stem cell identity, or stimulate the growth of existing stem cells throughout the body. Of course, such a drug may be harder to find than to imagine. Wnt (talk) 18:39, 13 November 2010 (UTC)

Armpit lines

What is the nature of the lines/ridges on this woman's right underarm? This one doesn't have them. Thanks. --Sean 16:37, 12 November 2010 (UTC)

The first lady, Floé, is clearly a muscular athlete who uses her arms in her sport and has increased the muscles in her axilla to the point that when she opens her axilla to this extent the muscles stretch against the skin making an ouline. If you raise your own arm and feel in the axilla you will detect these muscles, here [27] is a diagram to help understand my explanation. Richard Avery (talk) 18:40, 12 November 2010 (UTC)

I think this picture is a little more clear. The muscle involved is mostly the latissimus dorsi. Most people don't flex their lats to this degree (and even fewer do so with such little fat tissue to obscure things), so it's somewhat striking. But that's not unheard of; everyone is built a little differently. Most athletes only show a single mass for their bicep, but then again some show a split muscle - they just happen to have the right balance of large muscle and trim fat to allow it to show. Matt Deres (talk) 01:29, 13 November 2010 (UTC) I did a short image search to see if I could find an example of the "split" bicep and I'll tell you this for free: internet porn isn't nearly as gross as the stuff you see in an image search for "bicep".

You know there's actually no such word as bicep, right? The singular and plural are both biceps; the bicep version is a back-formation. I wonder how your search would have gone if you'd used the more formal spelling. But after the warning I'm not going to check it out myself. --Trovatore (talk) 07:25, 14 November 2010 (UTC)

I'm not entirely convinced of this. In this image it doesn't look like her body fat is that low to be able to determine that level of striation in those muscles, given the definition (or lack thereof) seen in her other muscles - the abdominal region, clearly visible here, is a good place to look for this. And when you view the uncropped image you realise the cropped version is a little deceptive, as the muscles aren't under any particularly great tension which could otherwise help bolster that explanation. With their nature and appearance, I'm kind of suspecting stretch marks. --jjron (talk) 05:12, 14 November 2010 (UTC)

I'm not convinced it's muscle, either. It's just such a tiny area, and it's not under as much strain as other parts of her body. I suppose another possibility is that they're simply wrinkles. --Sean 19:46, 15 November 2010 (UTC)

winds

Anyone know where I can find data on the speed and direction of winds in central Hampshire? Or any other climate data on the same area as well.

148.197.121.205 (talk) 18:55, 12 November 2010 (UTC)

http://www.winchesterweather.org.uk/historic_data.html (liked from http://www.weatherstations.co.uk/aws_map.htm)  Ronhjones  ^(Talk) 23:36, 12 November 2010 (UTC)

I understand that hurricanes hardly ever happen there. Clarityfiend (talk) 02:14, 13 November 2010 (UTC)

Russula brevipes

Does it have any close look-alikes? --The High Fin Sperm Whale 19:18, 12 November 2010 (UTC)

Looks like it's easy to get to genus, hard to get to species. In short, there are likely congeneric look-alikes within the same region. According to our page Russula,

"While it is relatively easy to identify a sample mushroom as belonging to this genus, it is a significant challenge to distinguish member species of Russula. This task often requires microscopic characteristics, and subtle subjective distinctions, such as the difference between a mild to bitter and a mild to acrid flavor."

I am intrigued by this "its quality is improved once parasitised by the ascomycete fungus Hypomyces lactifluorum, transforming it into an edible known as a lobster mushroom." Maybe the parasitic fungus (if present) can help clarify the host species, e.g. if the parasite is highly specialized to one species. SemanticMantis (talk) 19:49, 12 November 2010 (UTC)

Also, are you trying to ID a sample, or just curious? If the former, the commonness of R. brevipes will be a clue, e.g. if there are dozens of the same mushroom in a few different patches, I would have more confidence in the species ID. SemanticMantis (talk) 19:58, 12 November 2010 (UTC)

I am trying to identify this one. These were the only mushrooms in the patch, apart from some two others just out of the picture. And are there any poisonous mushrooms in the genus that can be mistaken for R. brevipes? --The High Fin Sperm Whale 20:02, 12 November 2010 (UTC)

I am not an expert in mushroom ID, and I am not advising you to eat this or any mushroom. Anything can be mistaken for anything with the proper lack of experience and perception. That being said, our List_of_Russula_species contains two poisonous examples. According to their Wikipedia pages, neither has the decurrent hymenium that our article on R. breviceps indicates. Keep in mind that list may not be complete or accurate. See also [28]. Seriously, eating mushrooms without expert identification is potentially deadly. Hope this helps, and that someone with more experience chimes in. SemanticMantis (talk) 20:28, 12 November 2010 (UTC)

The effects of heat on an electrical arc

This is merely a point of empirical curiosity, which seems not to be addressed anywhere else on the web (which is, in and of itself, curious). I have observed that an electrical arc, in this case generated by a 600,000 volt stun-gun, will ignore the UN-lit end cigarette,traveling the shortest, most direct route around the outside of it, to connect to the other post on the opposite side. However, light the cigarette, and repeat the same steps, placing the now lit end of the cigarette between the two posts of the stun-gun, and now the arc will actively seek out the "cherry" and go through it to get to the opposite post. An interesting side-note, at this point, is that the arc will completely ignore the cold ashes that have already burned, seeking out the still burning cherry, altering it's path to do so. So, my question, being two-fold, is this; Why does this happen, and how? Take your time in answering. I've wondered this for roughly twenty years. I can wait a little longer. It's not for a test, or any other kind of project. I simply have a scientific curiosity. If you can't figure this out, you're in good company. I've been seeking an answer from a wide selection of people, over the years, to no avail. However, I'd like to thank you for your time, and effort, in advance. I'm eager to see if this question, "How/why does heat/fire affect an electrical arc", can finally be put to bed. 74.60.220.9 (talk) 20:00, 12 November 2010 (UTC)

Well you will be interested to know that flames conduct electricity! In my boiler there is something called a flame sensor - it works be trying to send electricity through the flame and measuring how much current goes though, when the fire is on it completes the circuit. The same thing makes a Plasma speaker work. Ariel. (talk) 20:36, 12 November 2010 (UTC)

It's also the principle behind a Flame ionization detector. DMacks (talk) 20:40, 12 November 2010 (UTC)

(ec) Flame is a plasma, which unlike a gas conducts electricity. So the arc goes through the flame because that's the path of least resistance, in this case the path of least electrical resistance. The arc actually also ionizes the atmospheric gas, turning it, too, into a plasma, but the smallest length of gas that needs to be ionized by the arc involves taking a shortcut through the already-available plasma of the flame. Red Act (talk) 21:12, 12 November 2010 (UTC)

plus, an unlit cigarette is basically a wad of paper, which is a fairly decent insulator. an electrical arc will follow the path of least resistance, and since the cigarette has a small cross-section it will generally arc around it rather than through it. --Ludwigs2 15:47, 13 November 2010 (UTC)

There are also many amusing videos involving flames and microwave ovens that are based on this principle. Wnt (talk) 05:50, 14 November 2010 (UTC)