As far as I know, the [[F-102 Delta Dagger]] had never seen actual combat in its intended role, which was that of a supersonic [[interceptor]] for use against bombers -- instead, it was employed in [[Vietnam War|Vietnam]] as an escort fighter (unsuccessfully) and for ground attack (with surprising success). So, the only data that could indicate whether it would have performed well in its intended role comes from training combat exercises like the [[William Tell]] air-defense exercise (especially ones with live-firing of missiles); however, the article doesn't include this data, nor any links to it. Where can I find the data? (If you want to know, it's that "documentary" again -- what it asserts is that the Deuce was a piece of junk and a total waste of taxpayer money, whereas I'm trying to prove that it would have made a good interceptor, but it just wasn't designed for anything else.) [[Special:Contributions/67.169.83.209|67.169.83.209]] ([[User talk:67.169.83.209|talk]]) 02:01, 30 January 2014 (UTC)
As far as I know, the [[F-102 Delta Dagger]] had never seen actual combat in its intended role, which was that of a supersonic [[interceptor]] for use against bombers -- instead, it was employed in [[Vietnam War|Vietnam]] as an escort fighter (unsuccessfully) and for ground attack (with surprising success). So, the only data that could indicate whether it would have performed well in its intended role comes from training combat exercises like the [[William Tell (aerial gunnery competition)|William Tell]] air-defense exercise (especially ones with live-firing of missiles); however, the article doesn't include this data, nor any links to it. Where can I find the data? (If you want to know, it's that "documentary" again -- what it asserts is that the Deuce was a piece of junk and a total waste of taxpayer money, whereas I'm trying to prove that it would have made a good interceptor, but it just wasn't designed for anything else.) [[Special:Contributions/67.169.83.209|67.169.83.209]] ([[User talk:67.169.83.209|talk]]) 02:01, 30 January 2014 (UTC)
Revision as of 02:13, 30 January 2014
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.
In Kerbal Space Program, players have put together this map, showing the delta-V required to travel between the planets and moons of the Kerbal solar system. There's also this calculator for finding launch windows.
From what I remember, once you're out of Earth's gravity well, getting to Mars can be done with close to zero energy, if you don't mind taking millions of years to get there. It's theorized that Martian meteorites got here that way. 50.0.121.102 (talk) 08:53, 24 January 2014 (UTC)[reply]
This is equivalent to the Kerbal map for Earth and Mars. I think it is based on Hohmann transfers, like your map, not the ITN and other delta-V reducing techniques. Katie R (talk) 12:44, 24 January 2014 (UTC)[reply]
Apparently, the same authors have made a delta-v map of the real solar system. You can view it here. Some of it's shortcomings are discussed here where the NASA trajectory browser and how to use it is also discussed. Obviously, NASA is a rather more reliable source for this information if you are actually planning to make that journey. SpinningSpark13:11, 24 January 2014 (UTC)[reply]
mermaid morphology
Mermaids are mythical creatures with the top half of a human and the bottom half of a fish. However, I noticed that while depictions of mermaids show scales like a fish, the tail is oriented like that of a dolphin (that is, moving up/down (like a dolphin) rather than side to side (like a fish)). Anyone know why there is this inconsistency? I would think that even before any particular scientific classification of the animal kingdom people would be able to tell the difference between a fish and an aquatic mammal. 173.35.158.194 (talk) 03:20, 24 January 2014 (UTC)[reply]
"Fish" has not always had the strict definition it now has. At one time it simply meant any animal that lived exclusively in water. Hence, eating beavers in Lent, when the only animal allowed to be consumed is fish, has traditionally been allowed for Catholics (in the days when hunting and eating beavers was considered acceptable). SpinningSpark04:10, 24 January 2014 (UTC)[reply]
Agreed. In Moby-Dick (1851), Melville takes up the best part of a chapter rehearsing the various arguments as to whether a whale is a fish or a mammal, and finally comes to the conclusion that it is a fish. Alansplodge (talk) 11:19, 24 January 2014 (UTC)[reply]
I think the up/down tail is influenced more by the way humans swims, or might swim if they had a tail, see monofin. It would be very hard, near impossible, for a human to swim with a side to side motion. Disney has also played a large part in fixing the mermaid representation. Representations of mermaids prior to the widespread ability to swim amongst people do not always follow this pattern. SpinningSpark04:25, 24 January 2014 (UTC)[reply]
See Sirenomelia. Your mistake is in thinking mermaids are a fiction! :) [though I recall that article having a better picture of an otherwise healthy-looking infant ... so far I didn't find it in the history. I ought to write up some python app to run through all the history revisions and extract every image ever posted to an article. Wnt (talk) 14:14, 24 January 2014 (UTC)[reply]
I suppose it comes about from the thought that human hips and even, perhaps, knees would be present in the mermaid - that would certainly require the movement of the tail up and down rather than side-to-side - and that in turn means that the tail flukes would have to be whale/dolphin-like rather than fish-like. Remember that some cultures believed that the skeletons of large marine mammals like the manatee and dolphin were really mermaid skeletons. Also, note that some varients of the mermaid myth give them two "tails" - appearing as scaley legs, each tipped with a fin that looks like a diver's flipper. SteveBaker (talk) 15:43, 24 January 2014 (UTC)[reply]
This is probably the answer, for the most part anyway.
If you assume that your mermaid has human-like hips, (Necessary for 'sexy' mermaids) then the tail has to be oriented like a dolphin's for the whole thing to "work". (Especially for animation. Disney has probably contributed a lot to the modern mermaid imagery.)
Functional mermaid costumes actually used for swimming are pretty much required to have the flipper move front-back like dolphins, a human couldn't move her legs left and right like a fish.
There's a lot more diversity in mermaids that what you describe. As mentioned above, some have more "fish" style tails, and the cetacean/true fish distinction is not that old. For examples of mermaids that don't fit your description: the famous Starbucks mermaid has two tails, or a split tail:[1]. Some mermaids have fish tops and human bottoms, like this classic Magritte [2]. You also might be interested in this WP user's article on the "Mermaid problem" [3]. SemanticMantis (talk) 16:55, 24 January 2014 (UTC)[reply]
Sure, but he wasn't the first to depict mermaids that way, and my main point is that there isn't just one canonical mermaid, there are many depictions of this fantastical creature. SemanticMantis (talk) 17:51, 24 January 2014 (UTC)[reply]
I can well understand Fry's conundrum in an episode of Futurama where he befriends a mermaid, and agree with him that it would be much better if the fish and human parts were transposed. That way, at least, you could consummate the relationship. What, however, would the kissing feel like? Myles325a (talk) 03:32, 28 January 2014 (UTC)[reply]
Human brain question.
Does the human brain work best in pictures? There are phrases such as "a picture is worth a 1000 words" and our society seems to be full of pictures, diagrams, charts etc. However some people are very good with numbers or words. Others are good at reasoning and logical deduction. I know there are alot of articles and research around different types of intelligence and ways the human brain works but is there something which is common for all human brains? For example, do all human brains work best with pictures? Are all other types of intelligence, such as those I've listed just an addition to that? Clover345 (talk) 03:32, 24 January 2014 (UTC)[reply]
We have a very capable visual system and images are able to represent a large degree of data (depending on situation). Beyond that, though, I'm not exactly sure what it would mean to think in pictures as opposed to something else; at least, not in any way that's rigorous enough to attempt an answer. As for the idiom "a picture is worth a 1000 words", I think it's very subjective and very contextual: a picture of starving children will be more compelling than any description of starvation, a diagram of a machine will, probably, be more clear than a description, etc. However, there's plenty of things that we can't picture, or that pictures would mislead us about, mathematics and physics abound with these (picturing an atom usually ends up as imaging a small solar system, that is quite misleading, but also quite hard to avoid - etc.). Vision is a powerful method of presenting information/ideas, but it isn't the only one, nor do I think it is the sole primary one; again, it's a matter of what the idea is and who you are presenting it to. --Note: I have no citations and am approaching your question from a loose concept of "thinking in pictures", I'm sure there are more precise senses and answers, thus, if you had something more narrow in mind, just disregard this:-)Phoenixia1177 (talk) 06:00, 24 January 2014 (UTC)[reply]
You basically answered your own Q, some people think best in pictures, some don't. People blind from birth, for example, probably don't think in pictures. StuRat (talk) 06:47, 24 January 2014 (UTC)[reply]
In terms of raw bandwidth, our eyes are by far the fastest way to get data into our brains. Audio signals top out at around 40kHz, touch, taste, smell, balance, pain, proprioception and thermal senses have speeds in the tens of bits per second - but our eyes can pull in millions of pixels worth of data at tens of frames per second. There is also much more brain matter handling vision than sound or any of the other senses. That's why diagrams can generally convey data much more rapidly than the other options. SteveBaker (talk) 06:49, 24 January 2014 (UTC)[reply]
A human may stroll through a forest and catch sight of an ear and a striped tail projecting from the undergrowth. A person inclined to logical deduction would infer the probable size of a hypothetical creature that bears the ear and tail, then would seek in memory knowledge about known creatures of matching size, colour and habitat; that would be followed by estimations of the abilities of the candidate creatures to cause him harm; eventually he would gauge his need to carry out a life-protecting strategy such as retreating along his path. In contrast, a better equipped human in that situation has a lively pattern recognition i.e. "thinks in pictures". He immediately connects the (partial, noisy) evidence of the ear and tail to a vision of a tiger, which immediately stimulates his Fight-or-flight response, likely an escape requiring intense muscular effort, supported by all of the body’s systems. These scenarios demonstrate that A) the (human and animal) brain's ability to think in pictures has evolved as an optimum way to handle incomplete sensory data where any delay threatens survival, and B) the (human only) brain's trained ability to digest and develop logical deduction without emotive bias is the comparatively slow but only way that collective human Knowledge is acquired, validated and eventually preserved for generations in an encyclopedia. Educators are most effective when their teaching activates both types A) and B) of intelligence and they are less effective when learning depends on either A) alone (e.g. textbooks that are literally text-only such as language grammar books) or B) alone (videos without textual reference or formal exam). 84.209.89.214 (talk) 12:29, 24 January 2014 (UTC)[reply]
Roughly half of the human brain is devoted to vision -- processing visual input and controlling eye movements. As Phoenix said, our visual bandwidth is orders of magnitude higher than the bandwidth of any other mode of communication we can perform. Looie496 (talk) 21:10, 24 January 2014 (UTC)[reply]
This general topic is a recurring theme on the TV series "Brain Games": How when we see something only vaguely or partially, our brain uses our previous pattern-recognition experience to fill in the gaps as best it can, and assess the situation. We're not perfect, and that tendency to fill in can sometimes lead to mistakes or failure to see other things. But it's vital for survival. ←Baseball BugsWhat's up, Doc?carrots→ 11:32, 25 January 2014 (UTC)[reply]
O2 arena london structural engineering
Is there a reason the O2 arena in london is missing seating stands on the upper tier of the front part of the arena, from a structural engineering point of view? Clover345 (talk) 12:21, 24 January 2014 (UTC)[reply]
While seats full of people would add a significant amount of weight, even more weight could be added if it's filled with standing fans, which could be packed tighter. Do we know what the intended use of that area is ? Maybe it's meant for people in wheelchairs ?
As far as structural concerns, if it has a cantilever design, as opposed to support columns at the front, then the torque created at the cantilever attachment points would be a concern, and weight at the front of the upper tier would contribute disproportionately to the problem. Do we know if it has support columns at the front ? StuRat (talk) 17:33, 24 January 2014 (UTC)[reply]
Science of steaming food
I have a food steamer, which consists of an insert full of holes, placed inside a stock pot. The steamer holds the food and the stock pot holds the water. The problem is, since the holes on the steamer insert are down the sides and on the bottom, small food items or liquids drop through the holes. I'd rather eat them than have to clean them off the stock pot later.
So, my question is, if we eliminated the holes on the bottom, and halfway up the side, leaving only holes near the top, would it work as well to steam foods ? Or, for that matter, if we eliminated the holes entirely, would the air gap at the top be enough to fill the inside of the steamer with steam ? Would it slow the steaming process down, or even stop it, for some reason ? So, let's say we reduce the open area between the two by 90%, would that increase cooking time by 10X ? (I'm guessing no, that it would make little difference.)
(BTW, those who saw my previous post on this topic know I was looking for stainless steel bowl to place in the steamer to solve this problem. I ended up using a ceramic bowl, which works, but the volume is much smaller than if I could use the entire steamer basket. I also tried Crock Pot liners (plastic bag inserts), but they were too small for my steamer basket.) StuRat (talk) 18:56, 24 January 2014 (UTC)[reply]
Yes, that does happen, especially if I start with frozen ingredients, but I'm OK with that (also tomatoes and other foods will drain their juices). I end up with vegetable soup, with no risk of it burning, which is exactly what I wanted all along. If I make soup the normal way, I have to use excess water and/or watch it like a hawk, to prevent it from boiling dry, and I'd have to stir periodically to prevent burning at hot spots on the bottom, and burning at the waterline can also occur when using a gas stove. But this way, I can "set it and forget it". (Well, it would eventually boil dry, too, but the much larger water reservoir in the covered stock pot would take many hours to boil off.) Of course, this does create excess heat and humidity, but those are welcomed in winter. (I don't make soup in summer, I eat cold food then.) StuRat (talk) 01:13, 25 January 2014 (UTC)[reply]
I feel silly for saying something so obvious, but steamers are made for people who want their food steamed, not for people who want their food simmered. Looie496 (talk) 18:38, 25 January 2014 (UTC)[reply]
Well, call it a simmerer instead of a steamer then. It's actually a bit of both, as the food at the top and near the start is steamed, while that at the bottom and near the end is simmered. I like to put some lentils and rice in the bottom, as that needs to be simmered, while the veggies and salmon fillets at the top can be steamed. StuRat (talk) 02:07, 26 January 2014 (UTC)[reply]
If you don't want to actually steam the food, then you possibly just want a bain-marie. I have a similar stock pot plus steamer, and managed to find a metal bowl which fits in in the same way as the steamer (not designed as such, just happens to be the right width) MChesterMC (talk) 10:13, 27 January 2014 (UTC)[reply]
Yes, that was originally what I wanted, but it was difficult to find a large double boiler (that's what we call those in the US), as they all seem to be designed for melting a bit of butter or chocolate. I already own a small double boiler for that purpose. I actually find this steaming setup preferable, though, as I can steam a salmon fillet on top, which gives a much better result than either boiling or microwaving it.
But, if you independently added a bowl to your steamer, just like I did, this seems to indicate there is a need for a semi-steamer/semi-double boiler setup. Thus my Q, would plugging up most of the holes, only leaving a few open at the top, cause any problems ? StuRat (talk) 02:31, 28 January 2014 (UTC)[reply]
Fingers versus thumbs
I wasn't sure whether to ask this here at the Science Desk or over at the Language Desk. I settled on here. I am just curious, why is it that the thumb is (sometimes) not considered to be a "finger"? At other times, it seems that it is. I read the thumb article, which didn't really address this (unless I missed it). Thanks. Joseph A. Spadaro (talk) 20:28, 24 January 2014 (UTC)[reply]
Always? No, I have heard it said (many different times in many different places) that the hand has four fingers and a thumb. For whatever reason, the thumb is not "counted" as a "finger". I just wondered if there was some reason behind this? Thanks. Joseph A. Spadaro (talk) 20:35, 24 January 2014 (UTC)[reply]
According to Wiktionary, fingers are "one of the long extremities of the hand, sometimes excluding the thumb." According to the OED "one of the five terminal members of the hand; in a restricted sense, one of the four excluding the thumb." So yes, the thumb is sometimes excluded. I would have thought that it was fairly self-evident why the thumb is considered separately. SpinningSpark20:57, 24 January 2014 (UTC)[reply]
Thanks. But, what is the "self evident" part? I obviously know how the thumb is different than the other four; the question is why would it not be considered/called a finger? Thanks. Joseph A. Spadaro (talk) 21:42, 24 January 2014 (UTC)[reply]
Because language is funny that way, which usually is a sign that humans are funny that way. Are Neanderthals human or not? Are dogs wolves or not? Are whales fish or not?Yes, I know the scientific answer.. Is a foil a sword? Pluto a planet? --Stephan Schulz (talk) 21:56, 24 January 2014 (UTC)[reply]
The thumb is the only digit of the hand that is opposable to the other four fingers, has two phalanges rather than three, has greater breadth in the distal phalanx than in the proximal phalanx and is attached to such a mobile metacarpus (which produces most of the opposability). The etymology of the word: "tum" is Proto-Indo-European for "swelling" (cf "tumour" and "thigh") since the thumb is the stoutest of the fingers. 84.209.89.214 (talk) 23:46, 24 January 2014 (UTC)[reply]
According to the PIE language, you have twenty toes (originally digits, PIE *deik-) of which anmong the Proto-Germans, the fingers were the ones that caught (like fangs, German fangen), and the swollen ones, were the thumbs. μηδείς (talk) 03:53, 28 January 2014 (UTC)[reply]
Red tomatos that are green inside
I was at local deli where they build your sandwich while you watch. I noticed that the gelatinous insides of the tomatoes (where the seeds are) were all greens and very unappetizing. What causes this? --209.203.125.162 (talk) 23:54, 24 January 2014 (UTC)[reply]
With over 7,500 varieties of tomatoes, it's entirely possible that what you saw was simply an odd varietal; appetizing is in the eye of the beholder, after all. It could also be that the tomato really was still green and only the outside of the tomato was reddened, due to incomplete "forced" ripening via ethylene gas. Matt Deres (talk) 00:14, 25 January 2014 (UTC)[reply]
Yes, forced ripening would be my guess. If the tomatoes had naturally ripened, the part by the stem would be the last part to turn red, not the interior. StuRat (talk) 01:06, 25 January 2014 (UTC)[reply]
January 25
Gravity wells
Plot of a two-dimensional slice of the gravitational potential in and around a uniform spherical body. The inflection points of the cross-section are at the surface of the body.
How is this a two-dimensional slice? Unless "two-dimensional" refers to the image itself (it's a 2D picture, not a 3D model) in the style of The Treachery of Images, I can't understand; it looks very much 3D to me. It's not simply a mistake in the image caption, since the gravity well article says A plot of this function in two dimensions is shown in the figure. If it's in relation to the 3D stuff mentioned in the article's section on relativity, could you explain (basically) how that works? I don't understand the section at all. Nyttend (talk) 00:42, 25 January 2014 (UTC)[reply]
[Sorry, this is wrong – see below] It's a two-dimensional slice of the (intrinsically) curved four-dimensional geometry, embedded in flat three-dimensional space to show that (intrinsic) curvature. The 3D embedding space is not part of the slice. Likewise, to mathematicians, a sphere is a two-dimensional object with positive intrinsic curvature. -- BenRG (talk) 01:21, 25 January 2014 (UTC)[reply]
This is an embedding. The other image is a graph.Erm, now that I look at it, this is not an embedding at all. It's simply a graph of the gravitational potential on a flat 2D slice of Newtonian space, with the spatial coordinates on the horizontal axes and the gravitational potential on the vertical axis. It's two dimensional because there are two spatial coordinates. The "height" of the potential could have been shown in other ways in a 2D image, as SemanticMantis said.
The second image on the right shows what I was actually talking about. The gravity well (first image) is often mistakenly presented as an embedding (second image) because they look so similar, and now I'm adding to the confusion. They are really quite different not only in interpretation but also in shape: the gravity well is a paraboloid surrounded by a hyperboloid, while the embedding diagram is a portion of a sphere surrounded by a paraboloid (but, as I said, is often not drawn that way). -- BenRG (talk) 05:00, 25 January 2014 (UTC)[reply]
Our retina's are 2D surface and our brains are very good at turning 2D images into a perceived third dimension. Whence illustrating a plane warped into a third dimension is easy to perceive even on a 2D surface of a computer screen. On an infinite 2D plane, moving in single direction will never bring you back the origin. Curve that plane into a sphere, and you end up at the starting point. We imagine that very well as our brains are suited for it. Brains are not well suited for warping 3D space into a 4th physical dimension. There is no picture to show it. I believe one of the outcomes is that the earth is actually traversing a straight path while we perceive it as an elliptical orbit. The distinction between the gravity well and general relativity seems more like a modelling issue than a distinction. Sort of like Newtonian laws and relativity. They are different but not unrelated. --DHeyward (talk) 17:47, 25 January 2014 (UTC)[reply]
TrES-2b: Gas giant without clouds?
Curious. I was reading the article on TrES-2b and I noted that it is classed as a gas giant, but it is thought to not have clouds... what other forms would this gas be taking? — Crisco 1492 (talk) 13:17, 25 January 2014 (UTC)[reply]
The article says it's without reflective clouds, which is why it's so dark. There may be non-reflective clouds. Either way, it's perfectly possible to have an atmosphere without clouds. Clouds (at least as we know them) are masses of liquid or solid particles suspended within the gas. Rojomoke (talk) 13:36, 25 January 2014 (UTC)[reply]
While it's possible to have an atmosphere without clouds, as on Mars (at least part of the time), I'm not sure it's possible to have a gas giant without clouds. That's because there is so much atmosphere, even a very small percentage of particles in suspension will be visible as clouds.
For comparison, consider liquid water. A thin layer of water may or may not be clear, depending on the amount of particles in suspension. However, water that's miles thick is never completely clear. (Yes, water has a faint color all it's own, but even without that, I don't think you'd be able to see through water that's miles thick, due to the particles in suspension, unless that water was distilled in a lab.) StuRat (talk) 16:56, 25 January 2014 (UTC)[reply]
Converting motor to generator
The motor
Hello-
I am trying to convert a mechanical fan motor to a generator. Where should I go from here?
A good place to go is the article Electric motor where you can identify the principle of your motor. It does not appear to be a PM DC motor which is the only type that can be simply driven as a dynamo. If your purpose is to charge a battery or to power low-voltage lighting, the article on car alternators may suggest a better choice. 84.209.89.214 (talk) 19:16, 25 January 2014 (UTC)[reply]
BCAAs positive or negative affect on health
The article on BCAAs is confusing to me. It reads to me like BCAAs negatively impact health. My specific question would be in regards to the ALS paragraph that states in the article a link between excessive BCAAs and ALS, while a quick amount of referencing I've done from other website indicates BCAAs may be used to TREAT ALS. I'm no doctor or expert, but I feel like this article is leading and does not contain full accurate information on this suppliment. — Preceding unsigned comment added by 174.71.15.179 (talk) 18:15, 25 January 2014 (UTC)[reply]
They are referring to two different things. When talking about gold, it refers to Carat (purity), and in this context 24 carat is the highest possible, i.e. pure gold (12 carat gold is 50% gold and 18 carat is 75% etc.) When talking about diamonds and other precious stones, the carat is a unit of mass equal to 0.2 grams. That means that there is no theoretical limit. One can have a gemstone of 100 or even 1000 carats, but they would obviously be very expensive. - Lindert (talk) 20:05, 25 January 2014 (UTC)[reply]
I don't have a list for you, but the reason must be that those animals can't overeat. This would be primarily because the food they eat is so low in nutritional value, that it's difficult to get too much. Cows might fall into this category, as nearly constant eating of grass is required for them to get enough calories.
Also, some animals might lower their digestive efficiency when they eat more. The simplest way to do this is just to defecate whatever is in their digestive system when they overeat. This can all happen without any thought from them. Rodents, for example, seem to defecate constantly, with little control over it.
Incidentally, this also seems to be part of how human's control their weight. That is, if you eat 10 times your calorie requirement one day, you don't absorb anywhere near all of those calories. There are also some unfortunate people who never feel full, but they do tend to become obese.
Dogs tend to overeat, because like most carnivores, they encounter large prey on an irregular basis, rather than nibbling continually. (For the reason of continually eating, it seems unlikely most ruminants, which chew cud, will overeat under normal circumstances.) There are a huge number of articles on dogs overeating at google. My German Shepherd would do it when given a chance, especially with rawhide bones, then throw up. She had surgery once for "bloat" when she ate the string a turkey was wrapped in, and a lot of the trash that had absorbed the turkey fat. Bloat is a common cause of death for dogs. Unfortunately, looking for "not" a t google is difficult, so looking for animals that don't overeat is a difficult proposition. μηδείς (talk) 02:57, 26 January 2014 (UTC)[reply]
Yes, my brother had a dog that died from that. In his case the culprit was a grilled cheese sandwich, which apparently caused a blockage, which in turn caused the intestinal gas to build up until he couldn't breath. So, the dog died of flatulence. (They drove to the animal hospital as soon as they noticed his trouble breathing, but it was too late.)
Also note that humans overeat for much the same reason. That is, we evolved when big meals were few and far between, so it made sense to eat all you could in an attempt to avoid starvation during lean times. Fruits and veggies would have been available more often, but it's hard to get fat from those. StuRat (talk) 04:00, 26 January 2014 (UTC)[reply]
@ StuRat I don't have a list for you, but the reason must be that those animals can't overeat. This would be primarily because the food they eat is so low in nutritional value, What about fish being farmed where they are regularly fed a high protein diet to help them get as large a possible? - what about pigs or poultry that are fed high calorie food to increase their weight and cows are increasingly being kept in sheltered accommodation with artificial food that has to be limited to prevent over fattening. Cows might fall into this category, as nearly constant eating of grass is required for them to get enough calories. See above.
Also, some animals might lower their digestive efficiency when they eat more. The simplest way to do this is just to defecate whatever is in their digestive system when they overeat. This can all happen without any thought from them. Rodents, for example, seem to defecate constantly, with little control over it. So do sheep but sheep farmers go to lengths to fatten their animals, and successfully do so. So constant defacating doesn't control the weight of sheep. And dogs do not defecate more after a huge meal, they sit about for hours half asleep digesting it and turning it into body tissue. Rats and mice will get huge when fed excessively in captivity, so they don't use increased defecation to control their weights. Have you got a source that gives any support to your extra defecation theory.
Incidentally, this also seems to be part of how human's control their weight. That is, if you eat 10 times your calorie requirement one day, you don't absorb anywhere near all of those calories. Agreed but that is irrelevant to the question. The occasions when someone eats 10 times their recommended daily intake (lets say 20,000 cals) are vanishingly rare, Morgan Spurlock didn't get close to halfway that amount. There are also some unfortunate people who never feel full, but they do tend to become obese. This has nothing to do with what the OP asked. Stu, sometimes it is necessary to stop and think answers through, your answers often contain way too many weasel words that allow you to ease out when challenged. Caesar's Daddy (talk) 15:03, 26 January 2014 (UTC)[reply]
Perhaps I should have included the seemingly obvious: "This would be primarily because the food they eat is so low in nutritional value, in their natural environment." Obviously, we can supply high calorie foods to people or other animals, and they have not evolved a way to handle those, so they often get fat. StuRat (talk) 00:07, 27 January 2014 (UTC)[reply]
I can't speak for the entire species, but I've known Budgerigars that would stuff themselves until they made themselves sick if given unlimited access to something like a honey-coated seed bar or a long sprig of millet (i.e. leaving the thing in in the bird's cage and thinking it'll last a few days, but then discover that he's eaten it really quickly). Maybe it's something like eating a whole tube of Pringles and it being fine on the way down, but then paying for it afterwards... --Kurt Shaped Box (talk) 15:34, 26 January 2014 (UTC)[reply]
I have to clarify to make it not seem a stupid question. Of course, we see more light from the Moon — its luminosity is higher. But that's at least partly because we see it as a (much) bigger disk, so that doesn't count. What I want to know is, which is brighter at a given spot inside the disk.
Venus is only about 70% as far from the Sun, so the intensity of light falling on it should be roughly twice what falls on the Moon, and its albedo is also higher, by a factor of more than 5. So I would expect its luminance to be about ten times that of the Moon.
But that's if we can actually see Venus as a disk, which I'm not so sure about. According to phases of Venus, a person with exceptional visual acuity can resolve Venus as a disk under ideal conditions. But ideal conditions for that would be when Venus is closest to the Earth, and of course it can't be full under those conditions.
Interesting Q. Of course, as you noted, the brightness of Venus as viewed from Earth will vary with it's distance from Earth, which also affects it's phase. The brightness of the Moon also varies, but presumably you want the lit section when it is less than a full Moon, and that part might not vary by much. So, then, the question becomes, is the Moon always brighter, is Venus always brighter, or is it sometimes one and sometimes the other ? StuRat (talk) 03:53, 26 January 2014 (UTC)[reply]
Well, actually, as long as you can resolve Venus as a disk, its distance from Earth doesn't matter (much). The intensity of Venusian light falling on the Earth falls off as the square of the distance, but so does the solid angle that Venus subtends, so that cancels out. The brightness diminishes a tiny bit because of scattering by the not-complete-vacuum of interplanetary space, but that's a minor correction.
What matters is albedo times cross section--the apparent area of the face (visible disk) reflecting towards us. Venus is usually almost a point source compared to the Moon. Keep in mind also that this is proportional to the square of the apparent diameter. If the face of the Moon is ten times wider than the face of Venus, it has 100 times the area, and hence 20 times the brightness if Venus has five times the albedo. (I picked ten times out of the air as an example.) Obviously the distance determines the apparent size, but the relative apparent size is all you need to know for the comparison. μηδείς (talk) 03:58, 26 January 2014 (UTC)[reply]
It doesn't matter whether it's a point source "compared to the Moon". It matters whether it's a point source as far as our eyes are concerned. If you can resolve it as a non-point-source, even though much smaller than the Moon, then the apparent area cancels out. --Trovatore (talk) 04:05, 26 January 2014 (UTC)[reply]
No, that's wrong. The brightness is independent of our ability to distinguish between whether it's actually a point source or not. (Indeed, there's no such thing as a point source--that's a subjective effect of our perceptual systems, not a real phenomenon.) The actual diameter (relative to one's viewpoint) squared (assuming the same phase and hence shape) times the albedo is all that matters. I won't be responding to this again, it's not a matter of argument. I suggest you ask the same question at the math desk if you want confirmation. μηδείς (talk) 04:18, 26 January 2014 (UTC)[reply]
It depends how you're measuring it and at what point in their phases. According to Apparent magnitude, the moon is brighter than Venus for their respective greatest possible brightness. Generally, at new moon phase, the moon is dark, while Venus is bright at most any phase, until it slips behind the sun or otherwise gets lost in its glare. ←Baseball BugsWhat's up, Doc?carrots→ 05:04, 26 January 2014 (UTC)[reply]
Hmm, so the question there is what they mean by "brightness", for objects we can resolve as a disk. Do they mean the total light you see, or the total light per, say, rod cell? I'm asking about the second one, and it's not clear which one they mean. --Trovatore (talk) 05:25, 26 January 2014 (UTC)[reply]
(ec)The apparent magnitude article doesn't mention disks or points, so that's not totally clear. Also, it's not clear to me why a couple of stars have greater apparent magnitude than the sun, when those objects are (presumably) safe to observe through a telescope, while the sun obviously is not. And even the full moon can be pretty freakin' bright through a telescope, though I don't think it would blind you like looking at the sun would. ←Baseball BugsWhat's up, Doc?carrots→ 05:41, 26 January 2014 (UTC)[reply]
Most people resolve planets as disks even if they are unaware of it. Disks don't twinkle like point sources. Find the objects at night that don't twinkle and they are planets. There is no star (or planet or moon) that has an apparent magnitude greater than the sun (-26 or so) from the surface of the earth. There are stars that would be brighter if the earth was located the same distance from them but we have an average star so that is expected. Similarly, the sun has a larger apparent magnitude on mercury than earth. the answer to the question is whether you want to compare the same arc angle or the same distance. If venus were the same distance to the earth it would appear significantly larger than the moon. If you compare the brightness whether they consume the same amount of area (i.e. venus is further from the earth than the moon but they appear the same size), it's a matter of scaling it's current arc to the moons along with the brightness. --DHeyward (talk) 20:32, 26 January 2014 (UTC)[reply]
This is a tricky thing to get your head around. Consider this - the physics of light transport says that the brightness of a light source diminishes as the square of the range. When one light source is twice as far away as another, it's four times dimmer. HOWEVER, if you look at a tree that's (say) 10 meters away, it doesn't look 100 times brighter than a tree that's 100 meters away. That's because although there is indeed ten times as much light arriving at your eye from the close-up tree - that light is distributed over more rods and cones in your eye than the light from the more distant tree. When you double the distance to an object, all of the light from it is focused onto a quarter the number of rods and cones. The net result is that the diminution of light with distance exactly cancels out the fact that that light is focused onto a smaller area of the retina. Hence objects tend to maintain the same perceptual brightness, no matter how far away they are.
BUT (and this is the key here) once the light source is so far away that it's entire image is focused onto just one rod/cone - the effect of it's light begin shared over more or less cells stops happening - and a true range-squared diminution effect sets in. That's what we truly mean by a "point source" - a source that focuses to a point that's smaller in size to a single rod or cone cell.
So from a pure optical perspective, you'd expect objects of the same brightness to look equally bright no matter how small or how far they are from you UNTIL they get small enough to be focused on just one rod/cone - and then to start getting rapidly dimmer with size/range.
What greatly complicates this is that our brains know all about this effect - and they work to counteract it. This results in a translation of true brightness against perceived brightness that's hard-to-measure, and possibly different between individuals.
Ah, so your last two sentences are interesting (the rest of it is just a restatement of what I already said, but that's fine because I'm not sure everyone got it). Do you have any further information on this "brain" effect? --Trovatore (talk) 05:44, 26 January 2014 (UTC)[reply]
To make a long story short, Venus is brighter because it's closer to the Sun, with nice white fluffy clouds. Venus is at 0.7 AU, so it gets about double the light, plus it has an albedo of 70% or so versus something like 12% for the Moon (according to quick web searches). I wonder if every once in a while, geologically speaking, the Moon gets hit with a comet and a coating of hoarfrost makes it look five times brighter for a few generations? So Venus should be roughly 12 times brighter per unit area than the Moon. Of course, your optics may be blurry, in which case it will look dimmer, and how much depends on how blurry. Wnt (talk) 05:51, 26 January 2014 (UTC)[reply]
I think I already said all that. Question is, what's the bottom line? For human eyes. I understand that it may depend on distance, phase, and the particular human. --Trovatore (talk) 05:53, 26 January 2014 (UTC)[reply]
Well, according to angular diameter, Venus can sometimes be larger than an arcminute, sometimes much smaller. Though there's the wrinkle that when it is largest, it is 'new', so not bright at all, and close to the Sun. Practically, Venus at a good viewing angle should be less than half of that arcminute, and you'd still be seeing it less than half lit. According to discussions at naked eye there is some disagreement among sources about the practical resolution of the human eye, but it may go down to an arcminute in some people. I see no reason to suppose that some human doesn't have focus which is more or less perfect. Looking for some of the numbers online I found an interesting blog [4] which estimates diffraction- and cone photoreceptor based resolution at around 0.2 arcseconds, or maybe a bit more. The math looks believable, so... a curious coincidence seems to be that Venus makes up about as much of the sky as a photoreceptor makes up of the retina, give or take a factor of 4 or 5. But... the wheels come off the wagon at the next step. The thing is, retinas don't see light, people see light. Photoreceptors are averaged, contrasted, what came as a simple measurement becomes an aesthetic sensibility. It is the result of elaborate retinal processing. And just because one cone cell is shouting that Venus is brighter than the ground in broad daylight doesn't mean that that's how we perceive it. That final, subjective process seems to defy ready examination. Wnt (talk) 16:18, 26 January 2014 (UTC)[reply]
Just by the way, in case anyone is interested, there is a related discussion at talk:Moon; the article currently claims that the Moon is the brightest object in the sky after the Sun, which is true as most people probably interpret the word "brightest", but possibly not true in a more technical sense. Anyone who has thoughts on how to resolve the issue at that article is invited to comment on that talk page. --Trovatore (talk) 05:56, 26 January 2014 (UTC)[reply]
I looked at the same problem when I saw ChrisJBenson's first edit to the Moon article, but decided not to get involved because of the two different meanings of "brightness". Perhaps we need links to luminance and luminosity, as well as the existing note link to apparent magnitude. Dbfirs09:08, 26 January 2014 (UTC)[reply]
The full or near-full moon is so bright that it wreaks a degree of havoc with astronomy observations in general. Venus looks very bright when it's near a crescent moon. The question would be, at what point (if any) does Venus get close enough to the moon that the reflected light of the moon "drowns it out?" Or does Venus stay visible (to the naked eye) even when very close to the edge of the moon's disk? ←Baseball BugsWhat's up, Doc?carrots→ 13:20, 26 January 2014 (UTC)[reply]
Thanks, 140.180 for the link to surface brightness. I think we should mention in the article that Venus has a higher surface brightness (subject to your checking of the calculation, and BB's observation of no "drowning out" to confirm it). Dbfirs16:56, 26 January 2014 (UTC)[reply]
My concern, as I mentioned at that talk page, is that (whatever its technical definition), the term "surface brightness" sounds like something you would observe near the surface of the object, whereas I'm talking explicitly about what you observe from Earth. --Trovatore (talk) 19:24, 26 January 2014 (UTC)[reply]
Bugs's test is very nice, by the way. I don't ever recall seeing Venus just on the limb of the full Moon, but it would seem, based on abstract considerations, that you ought to be able to see it, no matter how close it is. If you can't, I'd like to know why. --Trovatore (talk) 19:29, 26 January 2014 (UTC)[reply]
Oh, I just realized — that can't happen; the geometry doesn't work. When the Moon is full, that means it's on the opposite side of the Earth from the Sun. You can't look that direction and see Venus. Still, it ought to be possible to see Venus right on the limb of a crescent Moon, so close that it actually looks like a bump on it. I have never seen that. --Trovatore (talk) 19:37, 26 January 2014 (UTC)[reply]
Oops, you're right, it wouldn't work. The question remains as to how much (if any) the full moon blinds the naked eye to any objects near it, such as bright stars or oft-seen outer planets. I know from anecdotal evidence that fainter objects such as comets show up much better on a moonless night. ←Baseball BugsWhat's up, Doc?carrots→ 21:14, 26 January 2014 (UTC)[reply]
That's certainly true. I still think it's a good test, conceptually, even if it can't actually happen that way. Rephrase: Imagine a helicopter carrying a searchlight, pointed at you, in such a way that it reproduces the full Moon in brightness and apparent size, and have it fly almost between you and Venus in such a way that Venus would appear just on the limb. Would you be able to see Venus, and would it look brighter than the searchlight? From the discussion so far, I think yes, but I'm not quite sure. --Trovatore (talk) 21:55, 26 January 2014 (UTC)[reply]
That's lovely, thanks! However — that's for a camera's optics. It doesn't quite answer the question for a human viewer. Still, great find, thanks again! --Trovatore (talk) 22:08, 26 January 2014 (UTC)[reply]
(140.180 here, didn't realize I got logged out)
According to this source, the surface brightness of Venus is 1.5 magnitudes per square arcsecond. The Moon's brightness when full is magnitude -12.7 (according to apparent magnitude), and its radius is 0.25 degrees, so it has a surface brightness of 3.3 magnitude per square arcsecond. So Venus is brighter per square arcsecond, by a factor of 5.
Surface brightness is independent of distance. It doesn't matter whether you measure it from Earth, from the Moon, or from Venus--Venus will always have a surface brightness of 1.5 mag/sq arcsec, and the Moon will always have a surface brightness of 3.3 mag/sq arcsec. --Bowlhover (talk) 22:04, 26 January 2014 (UTC)[reply]
That's actually one of my concerns about reducing the question to "surface brightness". The surface brightness of Sirius is much greater than the surface brightness of the Moon, but you wouldn't be able to see Sirius next to the Moon. The solid angle subtended by Sirius is so much smaller than what your eye can resolve that the surface brightness is pretty much irrelevant. For Venus, though, it may not be. --Trovatore (talk) 22:17, 26 January 2014 (UTC)[reply]
In astronomy, "brightness" almost always refers to the total amount of light emitted from an object. So does apparent magnitude. So does the layman's usage of the word "brightness", since nobody would say that Venus is brighter than the Moon. --Bowlhover (talk) 22:09, 26 January 2014 (UTC)[reply]
I was thinking about real surround-sound vs. virtual surround-sound (where timings are altered to make sound reach ears ever so slightly out of sync). Given that I only have two ears anyway, shouldn't virtual surround-sound be every bit as good as actual surround-sound? I think I've noticed real-life situations where I cannot tell whether a sound originates in front or behind me but I think that's an inherent flaw in a two-ear system. --78.148.110.69 (talk) 15:09, 26 January 2014 (UTC)[reply]
In theory, it could be. It is a lot easier to achieve with headphones than it is with loudspeakers. Headphones only require a channel for each ear (of which there are only two as you astutely observe). With loadspeakers, the entire sound field of the original room must be replicated. This can be done approximately only with a number of discrete loudspeakers, but is increasingly accurate the more sound channels and speakers that are used. See Surround sound#Creating surround sound. SpinningSpark15:40, 26 January 2014 (UTC)[reply]
One thing traditional headphones haven't done is change the balance between the ears as you move your head. This is an important factor in making the sound seem "real". I would expect that this could be done fairly easily now, though. Does anyone know if such a product is on the market ? StuRat (talk) 20:37, 26 January 2014 (UTC)[reply]
The answer is no. There is a common misconception that sound only enters through the two holes in the sides of our head - when in fact, the skull itself vibrates, reverberates and has certain resonances, sounds travel through the brain matter three times faster than through the air and the external parts of our ears perform subtle changes to the sound to help with directional awareness. If our auditory system was literally like two microphones, then you wouldn't be able to tell whether a sound was coming from in front or behind you - or above or below. In truth, our brains are able to detect subtle changes to the sound due to it passing through bone and brain and use these clues to spatialize sound more effectively than the "obvious" model.
The first efforts to improve stereo recordings for people wearing headphones were to put microphones into a plastic head, designed to reflect and refract sound just like a person's real head and record live performances that way. This is incredibly inconvenient for most recording studios. Modern "virtual surround sound" attempts to do the same thing with software post-processing of the raw audio. However, both of these approaches are only somewhat effective because each person's ears and skull shapes are different.
Another problem with this is that you need to make the recording differently depending on whether you expect the end-user to listen through speakers or headphones - and whether the headphones are "cups" or "earbuds" since the former allow your external ear parts to change the sound - where the earbuds do not. This means that commercial recordings with this kind of processing are not really feasible - so the calculations have to be performed as the music is replayed.
All of this means that true surround-sound is always going to be better than the virtual kind - UNLESS the real-to-virtual processing is highly tuned to your particular headphones and even to your personal physiology. Since nobody has yet managed the latter, it's clear that "real" surround-sound is going to be more convincing...*if* it's done right...which is another story entirely.
Hi there. I want to emphasize it is a biological, not medical question. I wonder if anybody has this information. What is the half-life of the fish oil taken as a vitamin/food supplement? Thanks, --AboutFace 22 (talk) 18:00, 26 January 2014 (UTC)[reply]
Are you sure you mean half life, as opposed, to, say, best by date? The former mostly applies to nuclear physics. The latter is printed on the bottle, and varies by product (e.g. liquid vs capsule) and method of storage (e.g. unrefrigerated or not). Check the label on the bottle. 88.112.50.121 (talk) 18:29, 26 January 2014 (UTC)[reply]
I would guess they are asking when it would deliver half of the vitamins as when it was new. Yes, it will vary widely, but perhaps we can come up with some estimates ? StuRat (talk) 20:39, 26 January 2014 (UTC)[reply]
I would guess the actual meaning is biological half-life — that is, how long the oil stays in the body. I'm not sure that's a meaningful question, for fish oil. It's not a drug. It's supposed to be metabolized, and the hope is that the outcome of that process is better than for other fats. --Trovatore (talk) 21:02, 26 January 2014 (UTC)[reply]
You are somewhat randomly focusing on the group of compounds called vitamins. Fish oil has little to do with that. "Half life" of those compounds is of even less practical use. You are not being helpful. 88.112.50.121 (talk) 21:13, 26 January 2014 (UTC)[reply]
It was actually the original poster who called it a "vitamin", which of course it isn't, but that's a little bit arbitrary (which nutrients are called "vitamins" and which ones are not is AFAICT largely a historical question rather than a clearly-defined meaningful categorization). --Trovatore (talk) 21:18, 26 January 2014 (UTC)[reply]
I did not expect so much confusion. When a person swallows a medication a curve called bioavailability may be measured. Let's say a peak blood concentration after one hour upon ingestion is so many mcg/dl in plasma. The question is how long does it take for that concentration to decrease by 50%. It is a standard parameter for many drugs. I called the fish oil a vitamin to avoid a suggestion that this is a medical question. There is no need to go into a long discussion on it. We can talk about omega-3 fatty acids, etc. I want to know the half-life of the fish oil, period. Thanks --AboutFace 22 (talk) 21:37, 26 January 2014 (UTC)[reply]
That seems like a fair question, though I don't know the answer. However, in case anyone does, you might clarify whether you really mean the oil molecules themselves in unmodified form, or if you accept the constituent fatty acids, either free or in some other combination. --Trovatore (talk) 21:43, 26 January 2014 (UTC)[reply]
Möller’s Cod Liver Oil is a pure natural product without preservative. An opened bottle should be kept for a maximum of three months in the refridgerator before it should be replaced. This is due to exposure to oxygen from light and air every time the bottle is opened. Hence, it is important to put the screw-cap on directly after consumption to prevent exposing the oil to oxidation (becoming rancid). 84.209.89.214 (talk) 00:07, 27 January 2014 (UTC)[reply]
You see, the first pass through the liver is important as we know. It may kill some portion, however that should not affect the bioavailability curve. Then usually chemicals are divided into free floating and plazma protein bound fractions. How easily the proteins part with the chemical may determine the half-life I am looking for. It is all a big question mark for me but is important to know. --AboutFace 22 (talk) 00:25, 27 January 2014 (UTC)[reply]
There are insufficient data points to be able to accurately calculate half-life from those graphs, but assuming an exponential decay from the peak of the graph we can obtain time constants of 2.104 and 2.187 days for the orange and blue curves respectively. The relationship of exponential time constant to half life is ln(2) giving half-lives of 1.46 and 1.52 respectively. If you wish to measure from the time of ingesting, the 24 hours to the peak of the curve must be added making 2.46 and 2.52 days respectively. However, this is likely to be an underestimate. If more datapoints were shown we would likely see the rounded top of the curve initially falling slower than an exponential. So the answer is likely to be 3 to 4 days based on the scanty information in those curves. SpinningSpark11:13, 27 January 2014 (UTC)[reply]
The reason I haven't touched this one is that it is difficult to figure. I mean, exogenous fatty acids can end up going straight into myelin,[5] where depending on how and what you measure they can have very long or short half-lives.[6] So depending on the precise question you're really interested in, the interesting answer could be all over the place, minutes to months. Wnt (talk) 17:05, 27 January 2014 (UTC)[reply]
No, I think OP DOES mean half-life. Fish have phospherous in them, and that is mildly radioactive. So my answer would be have as many pills as you like, but stop when you start to glow in the dark. Myles325a (talk) 03:41, 28 January 2014 (UTC)[reply]
Washing away a flu
Does taking a shower or bath actually help get rid of a cold or flu? I've heard it said that doing so washes away toxins or waste that is sweated out and therefore helps the healing and recovery. Is there anything that you can cite that says that this helps? Dismas|(talk)20:54, 26 January 2014 (UTC)[reply]
I can't see it helping by that mechanism, but the heat, humidity, and motion might help one to cough up phlegm. Strong smelling shampoos and body washes might also help this process.
And just feeling clean might make the person more willing to go out and face the world. So, they may not have a lower viral count, but might feel better at least. StuRat (talk) 21:23, 26 January 2014 (UTC)[reply]
Basically, no. Any "toxins" that make you feel sick are immune factors in the blood like interferon or dead cell products in the blood stream. Viruses only live inside living cells such as the lining of the respiratory and gastrointestinal tract, and can travel through the blood as well. As mentioned, washing will help prevent transmission and the heat and humidity may be soothing, but it won't remove toxins or otherwise affect a flu or rhinovirus infection. Only small molecules can really leave the body passively through the sweat, like alcohol, and this only at a very-low rate, which is why you die if you don't have functioning kidneys, bowels and a liver. μηδείς (talk) 01:23, 27 January 2014 (UTC)[reply]
A quick rule of thumb I've developed is to ignore any folk advice that has to do with "removing toxins from the body" as it's almost 100% bullshit. Matt Deres (talk) 18:25, 27 January 2014 (UTC)[reply]
A favorite example of that was those foot pads that claimed to pull the "toxins" out of your body through the soles of your feet. They said that it worked 'naturally' just as trees flush waste products out through their roots...it had a very pretty graphic of the tree absorbing raindrops though it's leaves and passing the resulting 'toxins' out of the roots...so it must be true! SteveBaker (talk) 21:02, 28 January 2014 (UTC)[reply]
Yes it is possible. The cutting stylus for a Gramophone record unavoidably transfers some of the subsequent groove wall's impulse signal into the previous groove wall. A quiet passage followed by a loud sound will allow one to hear a faint pre-echo of the loud sound occurring 1.8 seconds ( = 60/33⅓ ) ahead of time. This problem can also appear as "post"-echo, with a tinny ghost of the sound arriving 1.8 seconds after its main impulse. This link explains groove echo and shows photos of a recording lathe that is able to spread grooves i.e. "add land" to reduce the problem. Echos with shorter delay also occur due to analog tape print-through. 84.209.89.214 (talk) 23:55, 26 January 2014 (UTC)[reply]
How does post echo form? I assume the problem for pre echo is that when the stylus cuts the next groove, it pushes some of the laquer of the (now) wall between there and the previous groove back into the previous (the stylus pushing some of the material sideways rather than simply scraping it out). But the whole laquer from the location of the stylus in is not yet cut. And when the stylus does get to the next one and cuts there, why is it not able to cut out any deformation that may have occurred? DMacks (talk) 04:31, 27 January 2014 (UTC)[reply]
[Banned user's contribution deleted]
I agree that as the cutter deforms the master disk in the N'th revolution of the disk, it's imposing this new audio on top of the N-1th revolution. That should result in a 1.8 second pre-echo ("HELLO WORLD" becomes "helloHELLOworldWORLD") where you hear sound coming from 1.8 seconds into the future. It seems unlikely that the N-1th groove is going to have much impact on the path that the head takes when cutting the N'th groove so post-echo seems unlikely. What DOES seem likely is that the act of replaying the disk causes the problem. As the stylus is accelerated left and right and up and down, it's going to impose forces on both sides of the groove. That must somewhat distort the vinyl and result in both pre-and-post echo ("helloHELLOhello"). This seems like a more likely mechanism anyway because I presume that the master disk is cut into some kind of metal substrate that would be resistant to deforming the previous grooves.
Tape print-through can also produce both pre-and-post echoes - and those would be present even in the master disk if it was mixed down from tape. However, tape print-through is usually only a problem when tapes are stored for long periods without being periodically re-wound onto new spools. It seems unlikely that this would happen to any significant extend with most vinyl disks being made within days of the performance being recorded.
One particularly fun record is a Monty Python disk where they recorded two parallel grooves on one side of the disk - so you hear a completely different recording, randomly, half of the time! It would be interesting to listen for 'echoes' of something you're NOT going to hear - because that would clearly distinguish groove distortion from tape print-through. SteveBaker (talk) 20:30, 28 January 2014 (UTC)[reply]
I didn't know there was a name for it! I know they used to use them for gambling on the outcome of horseraces - where they'd make a disk with six parallel tracks - each narrating a horserace with a different outcome. The disk would start playing on one of the tracks at random - and people would then bet on the outcome. SteveBaker (talk) 21:36, 29 January 2014 (UTC)[reply]
Do wild rabbit colonies abandon their burrows and dig new ones after a rabbit dies in there? I'm assuming they would hide underground if in pain, like dying cats will try to find a quiet "safe" place. Or is there a different reason for their movement? I live near a hillside which is full of rabbit holes, but actual rabbits seem to be mostly at one end. 86.144.47.4 (talk) 21:38, 26 January 2014 (UTC)[reply]
Assuming you're correct, and they do that, the obvious reason would be to avoid the diseases they might catch from the decomposing rabbit corpse in there. The smell might also attract scavengers. Of course, rabbits wouldn't reason any of this out, they would just have the instinct to dig a new burrow in that case (because those with that instinct would be more likely to survive and pass on their genes). StuRat (talk) 23:57, 26 January 2014 (UTC)[reply]
I doubt if they would do much damage to the tree either way. However, they could cause injuries to people. Spikes in trees can be dangerous when some day they are cut down with a chain saw. I'm not sure if a staple would be able to damage a chain saw, but maybe large ones might. StuRat (talk) 23:54, 26 January 2014 (UTC)[reply]
There's a guy on one of the educational channels [Animal Planet] who builds elaborate tree houses.[Treehouse Masters] His process involves drilling pretty good sized holes in the sides of the trees and embedding something like a large metal "molly" as a basis for supporting the corners of the structure. If he thinks something like that is harmless to the tree, I wouldn't think staples would do much. ←Baseball BugsWhat's up, Doc?carrots→ 00:46, 27 January 2014 (UTC)[reply]
There are two potential problems from the tree's point of view. The first is that the tissues that carry the sugar and water (phloem and xylem) in a hardwood tree lie peripherally around the trunk, in the outermost living ring, just under the bark. A single puncture will hardly be problematic. But if you ring the bark it will kill the tree (slash and burn agriculture) by cutting off the flow to and from the top of the plant. There is sideways flow, but it is limited. So you can also kill the tree by cutting off significant flow of fluids at various heights. A large number of gashes can do this. And a disease like Dutch elm disease does this as well, by killing off spots of conductive tissue at various places, eventually ringing the trees.
That brings up the second point, that puncturing the bark allows the entry of insects and funguses like Dutch Elm and the Asian long-horned beetle. The solution is not to damage a tree too much, and to use a sealant you can get at a garden center either when you puncture it or if you remove objects puncturing it. μηδείς (talk) 01:08, 27 January 2014 (UTC)[reply]
Also more susceptible to viruses when the "pipes" are exposed. Better to leave things in (and not put them there to start), as long as they're not toxic (or dangerous to non-trees). I don't think rust has any harmful effects, but I'll check. InedibleHulk(talk) 02:18, January 27, 2014 (UTC)
Apparently there are "rust diseases", which make plants look rusty. Not sure I'm a capable enough Googler for this one. InedibleHulk(talk) 02:21, January 27, 2014 (UTC)
Nice link. The narrative doesn't mention that although the bark and cambium will envelop things attached to them, they won't lift them off the ground, because the only parts of the tree that gets longer are the new shoots on the end of the twigs, the branches and trunk only grow wider, not longer. In London, timber merchants looking to acquire fallen trees for their wood often run a metal detector over the trunk to find out if it's full of shrapnel from The Blitz. Alansplodge (talk) 13:58, 27 January 2014 (UTC)[reply]
I believe that depends on the type of tree. Bamboo, for example, grows in length at each joint, allowing it to grow faster and kill off the competition by stealing it's sunlight. (Some might argue that bamboo is a grass, not a tree, but most people would call it a tree.) StuRat (talk) 21:22, 27 January 2014 (UTC)[reply]
Also, I think some other tree species do grow upwards slightly at all points. The tree in the pic has a bicycle which has clearly been lifted off the ground, for example. I doubt if it was suspended in air when the tree grew through it. And if the ground washed away, I'd expect to see exposed roots. StuRat (talk) 00:34, 28 January 2014 (UTC)[reply]
The branch of a woody tree (including the crown stems) will only grow lengthwise in its first season, while it is green. (That even applies to grasses which become woody like bamboo.) Given the height of the bike, it must have been placed in the crook of a branch at the height where it is still found--and a new twig in its first year of growth would not have held its weight. μηδείς (talk) 01:23, 28 January 2014 (UTC)[reply]
The question that hasn’t been asked yet is : Why use staples? There are many good contact adhesives available now that will keep a notice stuck to a tree long after another Katrina has come and gone. Because bark doesn’t grow, the glue eventually falls off.--Aspro (talk) 16:51, 28 January 2014 (UTC)[reply]
Good question. I suppose staples are much quicker and easier to use. There are many tree barks that contact adhesives don't stick to. If you want to be ecologically friendly, don't use trees for your fly-posting! Dbfirs17:05, 28 January 2014 (UTC)[reply]
True, but in many neighbourhoods, street lights out number trees these days. There is also now a plethora of suitable contact adhesives available (Try smearing yourself, first with supper glue, then do bit of tree-hugging. It will take the fire department -hours and hours - to peel you off). Also, try cutting out a Stencil and spray painting your flier on the sidewalk, walls, fences etc. Don't forget to add a QR code to link the reader to a website that gives further information.--Aspro (talk) 22:27, 28 January 2014 (UTC)[reply]
Technically, nuclear science deals with the nucleus of the atom, while atomic science, if there was such a term, would presumably deal with the entire atom. However, this is just chemistry. But, somebody might also use "atomic science" as a synonym for nuclear science, I suppose.StuRat (talk) 03:48, 27 January 2014 (UTC)[reply]
However, out article on Atomic physics does make a distinction from Nuclear physics and it is exactly as StuRat supposes above. Nuclear physics is addresses only the nucleus and atomic physics addresses the with the whole atom. But that seems to be a technical distinction and both articles lack citations on the difference. Richard-of-Earth (talk) 11:34, 27 January 2014 (UTC)[reply]
Kriegslok
Many railfans know how to distinguish different types of steam locomotives by sound; e.g. the "Shay" narrow-gauge engine puffs at six beats to the bar, the "Lord Nelson class" express engine at eight beats to the bar, many of the Gresley locomotives have a syncopated beat because of the derived valve gear, etc., etc. So can anyone describe to me how a German Kriegslok freight locomotive sounds, especially in comparison to a French freight engine? Thanks in advance! 67.169.83.209 (talk) 06:14, 27 January 2014 (UTC)[reply]
Thanks! It sounds to me like the sound of the exhaust is rather sharp -- which would make sense because to simplify production, the pistons probably weren't chamfered like they are in many other steam locomotives. 67.169.83.209 (talk) 05:31, 28 January 2014 (UTC)[reply]
download offline medical division content only
Dear Sir
I am a pharmacist and I wish to download offline data of wikipedia of what is concerning the medical section.
How can I download only that speciality.
Do I have to download the 9 GB zm file or there is a file for each devision that can be downloaded.
Thank you — Preceding unsigned comment added by 62.114.71.69 (talk) 13:17, 27 January 2014 (UTC)[reply]
You can also create a "book" with a selection of pages. There is a link in the left column of the page. You can add an entire category to it, then export in several formats including PDF. Katie R (talk) 17:38, 27 January 2014 (UTC)[reply]
Today I was trying to stir ground cinnamon into my mass market triple shot iced coffee. I noticed the ground cinnamon just did not want to blend into the coffee. It wanted to float on top and resisted mixing. What's this property called? --Navstar (talk) 23:01, 27 January 2014 (UTC)[reply]
I believe most chemically inert, water-insolublepowders can act similarly hydrophobic. See the pictures at Superhydrophobe, but think about the powder in the liquid instead of the liquid on a rough surface. Wetting is the converse process, and also has some good pictures. When you have granular material instead of surface roughness discussed in the articles, then clumps can form where the outside is wetted and cohesive, but the inside stays dry, and this makes it even more difficult to mix into an homogenous suspension. I can't find a WP article that specifically discusses the hydrophobic behavior of powders, but Mixing_(process_engineering) alludes to some of these issues. SemanticMantis (talk) 23:47, 27 January 2014 (UTC)[reply]
Now for some practical suggestions for your case:
1) Mixing works better at higher temperatures, so mix in the cinnamon to hot coffee, then add the ice. Of course, if it's already iced when you get it, this option is out.
2) Pour a small portion of the coffee into a large container with a top, add the cinnamon, seal the top, shake well, then open it up and add the rest.
3) Use a liquid cinnamon flavoring agent instead of powered cinnamon. Of course, this is likely to contain sugar and other items you may want to avoid. StuRat (talk) 00:44, 28 January 2014 (UTC)[reply]
(Practical solutions to avoid situation described)
4) Simply add the cinnamon with the ground coffee before you brew it. —(For iced coffee, brew double-strength before adding ice)
My grandmother used to sometimes add a few drops of brandy to dried spices. Presumably, as alcohol is a wetting agent this helped but I can find no references. So maybe this is Folklore. Mind you, as your end point is a nice cup of iced coffee, then a dollop of brandy can only improve things.--Aspro (talk) 17:06, 28 January 2014 (UTC)[reply]
That's is a good point. As cinnamon is bark consisting of cellulose and lignite, then even finely ground it will just float. Infusing the coffee with a cinnamon stick (and then removing) might be what the OP is after. However, if it is filtered coffee, the filter will remove those grounds. Still, the OP mentions “mass market triple shot iced coffee”. Well, I don't know what mass market coffee is, unless he means something like nescafé in which case its is like trying to [make a silk purse of a sow's ear]. Tap-water is a better re-hydrant. So, in short he may just need to infuse a suitable sized bit of cinnamon stick for a few minutes in hot water and then add the coffee to that water infusion.--Aspro (talk) 20:07, 28 January 2014 (UTC)[reply]
In the movie, Her, the main human character has single earpiece (a futuristic Bluetooth-type earbud) he uses to interact with his phone/computer. It's implied that he can listen to stereo audio. Obviously, we don't have this technology today (at least not at the consumer level). But how would something like this work? --Navstar (talk) 01:33, 28 January 2014 (UTC)[reply]
Well, if the single ear bud blocks ambient noise and delivers one channel (either left or right), and you have another speaker somewhere in the room with the other channel playing, that could work. Others in the room would hear mono, while the person with the ear bud would hear stereo. StuRat (talk) 02:17, 28 January 2014 (UTC)[reply]
There is a technology (see Sound from ultrasound) to direct sound to appear from a point in space that's remote from the equipment that produces it. There have been efforts to use this in advertising and as a military weapon. Imagine you're walking with a crowd of people in a shopping mall and some facial recognition software recognizes you as a frequent shopper at one of the stores...a directed sound system could whisper into your ear: "Hi Navstar! There's a special offer waiting just for you at our store, over to your right."...and nobody but you would hear it. The sound system could follow you around in three dimensions, beaming sound into your ears no matter where you go. It's a horrible idea - but advertisers love it.
So I suppose, with enough advanced technology, you could wirelessly beam sound into people's ears without needing ear-buds at all...and certainly it could be possible to have a device that fits in one ear transmit sound to the other ear using that kind of mechanism. Of course this is all science fiction right now - but it's definitely not impossible. SteveBaker (talk) 02:56, 28 January 2014 (UTC)[reply]
Don't know what show so not sure what the prop is. But human sound perception of sound is more complex that just L/R. If you just had a left ear, receiving the same signal delayed and modulated might mimic some aspects of reflections and source. One eyed people can drive, not because they have binocular vision, but because of cues they perceive give them a form of depth perception. --DHeyward (talk) 03:05, 28 January 2014 (UTC)[reply]
I agree with you...but your one-eyed driver analogy could use some explanation. Our ability to estimate distances uses at least six different mechanisms (focal distance, binocular accomodation, parallax from small head movements, relative size of object compared to those at a known distance and image size on the retina of a known-sized object, atmospheric attenuation). A person with only one functioning eye can still use five out of those six methods. Furthermore, the binocular accomodation method (which is the one they don't have) is only effective over a range from a couple of feet out to maybe 20 or 30 feet. Beyond that, it has little value.
It's not clear to what degree effects like phase lag and relative sound amplitude have on directional hearing, and it gets more complicated still when sounds are able to reflect off of the bones of the skull and are refracted by the higher speed of sound through the brain compared to the air. HOWEVER, when sound is fed to you through two earbuds, then ALL of those tricks are wiped out - or worse, they are subverted to making it even more obvious to the listener that this isn't "real" surround sound. So the analogy to the one-eyed driver who has lost only one of the available perceptual mechanisms - isn't really correct. SteveBaker (talk) 20:10, 28 January 2014 (UTC)[reply]
You're right. Still I suspect adaptations by individuals are beyond interpretation. I suspect slight adjustments of head position would allow perception of location that is not explained by a fixed position. A differential analysis by the brain of 0 degrees and 45 degrees of the same source tone would easily isolate location and possibly distance. Coupled with the data of moving the head to adjust amplitude makes me think the brain is more sophisticated than a 2 input DSP. --DHeyward (talk) 06:23, 29 January 2014 (UTC)[reply]
Finding milliamps of electric batteries (Ni-Cad) used in portable drills (such as a Black/Decker 12 volt unit from Lowes)
I have a few portable drills several years old that are missing battery charges. Buying (if available)
would be costly and would make no sense. I have 12 volt DC plug in transformers with various ratings
from 300 ma to 3 -4 amp. I will experiment by attaching a transformer to the internal battery
posts but need some idea of amperage range. I could insert a pot and start at the low range but
a bit stuck on risk of damaging motor. Can anyone advise me on getting unstuck or do I remain
within my Scottish clan which include Gearloose McDuck. Thans — Preceding unsigned comment added by 108.195.4.48 (talk) 04:38, 28 January 2014 (UTC)[reply]
The current drawn will depend on the motor of the drill and also on the load in use. I would expect that under heavy load the drill might require five or even ten amps, so your transformers might be inadequate and might be overloaded. Another suggestion would be to connect your drills to a car battery (or one of those handy 12v portable booster batteries), but you will need to include some protection against short circuits. (If it is only the charger that is missing but the battery is OK then almost any 12v DC charger will work, but limit the current to one tenth of the total capacity i.e. charge at the "ten hour rate", or to the rated current of the charger if this is lower. The battery is unlikely to hold an adequate charge if it has been unused for years.) Dbfirs11:19, 28 January 2014 (UTC)[reply]
F-102 safety record
Hello all, I've just watched an amateur "documentary" film that alleges that the F-102 Delta Dagger had suffered "literally HUNDREDS of... crashes" due to the bad low-speed handling characteristics of its delta wing; however, I strongly doubt this claim, because had that been the case, most if not all F-102s would have crashed at some point. I tried reading the article, but it says nothing about the type's safety record. Does anyone happen to know whether what the film says is true, or whether it's just another piece of anti-military bullshit? 67.169.83.209 (talk) 06:47, 28 January 2014 (UTC)[reply]
The F-102 does seem to have had a high loss rate: "Of the 875 F-102A production models that entered service, 259 were lost in accidents that killed 70 Air Force and ANG pilots." [8]AndyTheGrump (talk) 07:07, 28 January 2014 (UTC)[reply]
Thanks! So, the "literally HUNDREDS" part was somewhat of an exaggeration, because that phrasing connotes at least 300-400 losses -- at least, the way I see it. 67.169.83.209 (talk) 07:17, 28 January 2014 (UTC)[reply]
Well, to me 'hundreds' would suggest 'at least two hundred'. Actually though, the more meaningful figure may be the hourly accidental loss rate: 13.69 per 100,000 hours flown - three or four times the figures for most current U.S. fighters (same source as above). Modern zero-zero ejection seats will probably have reduced fatality rates considerably too. AndyTheGrump (talk) 07:39, 28 January 2014 (UTC)[reply]
Note that 1950s high performance interceptors were all a lot more dangerous than their modern counterparts. I can't find any comparable figures, but the Lockheed F-104 Starfighter was known as "The Widowmaker" and its British contemporary, the English Electric Lightning, was given the soubriquet "The Flying Coffin" (see List of accidents and incidents involving the English Electric Lightning). The F-104 initially had an ejector seat that shot the pilot down through the floor; not only did this make ejecting at low altitude impossible, but in case of a wheels-up landing, the ejection hatch was ripped off and soil was scooped up into the cockpit, burying the pilot alive. Alansplodge (talk) 13:58, 28 January 2014 (UTC)[reply]
I can't put my hands on the figures but during the two years of the battle of Britain, more than twice the number of aircraft where being lost in training accidents than in combat. It was not so much that the aircraft per se were dangerous but the were being flown to their very limits. Thus, often escaped their Flight envelope. When were you last on a Boeing Jumbo, where the pilot treated you to a few low altitude barrels rolls and a loop de loop? Simulators have done a lot for safety and pilot/crew survival. Back in the days of the English Electric Lightning, learning by trial and error, often lead to a short career if one got it wrong -just once. It wasn't the aircraft's fault nor that of the pilot. It was the need to be better skilled than the enemy -should that day come to prove it.
When I worked on flight simulators, our scenery artists were instructed to put invisible barriers under all of the bridges in order to persuade pilots (who seemed unable to resist the temptation to fly under them) from coming to believe that they could do so safely! The temptation to push that envelope is everywhere in the rather extreme "Type A personalities" of many fighter pilots. SteveBaker (talk) 21:32, 29 January 2014 (UTC)[reply]
Note that "literally HUNDREDS" of crashes may be referring to a different number than the "259 lost in accidents". Many crashes leave the aircraft in a repairable situation - in which case it's not considered to be a "loss" - which implies that the airplane is too severely damaged to return to service. With the near-certainty that there were more "crashes" than "losses" - it's seems almost certain that more than 300 "crashes" have occurred - with 5 our of every 6 crashes resulting in a loss and one out of 6 resulting in a repairable plane. However, I agree with Andy - even 200 does indeed count as "hundreds" - it's basic English language - the word "hundred" means 100, stick an 's' on the end to form a plural and all you need is more than one "hundred" - so 200 certainly counts as "hundreds". If the phrasing had been "several hundred" - then maybe I'd agree that this expresses a number over 300. SteveBaker (talk) 20:00, 28 January 2014 (UTC)[reply]
Do you run your wood stove mostly at low heat with the damper in most of the time. The relative coolness of the stove under these conditions will encourage tars to condense out. Forget chemical fixes. Occasionally, run the stove at a high temperature to burn off these residues. (what type of flue do you have? You don't want to get a chimney fire in the process.)--Aspro (talk) 17:15, 28 January 2014 (UTC)[reply]
It looks like that would probably help creosote to flake off , but it is not usually a recommended as a safe/efficient method. More of an "old country fix." Here's some discussions I've found [9], [10], [11]. There's a lot of people saying it works, and here's a video that claims to show evidence [12]. I've never tried this personally; proceed at your own risk. Also note that chimney fires are very dangerous. Cleaning creosote can prevent them, but attempting to burn something much hotter than wood could also start an nasty fire, especially if you have lots of built up creosote. SemanticMantis (talk) 17:17, 28 January 2014 (UTC)[reply]
I have a lot of respect for folk wisdom. So I have found this:Aluminium fume The predominant risk associated with aluminium welding is exposure to ozone.. Ozone would indeed degrade tars. My folk-wisdom of a hot-burn dates back to before aluminium cans, when pepsi and coca cola came in steel cans and had to opened with one of these things. [13]. Still, I am open to new ideas and methods, indeed - I don't need aluminium cans anyway as I have adopted modern central heating. It seem to be only in counties like the US that have to resort to soda cans ;-)--Aspro (talk) 20:45, 28 January 2014 (UTC)[reply]
Cola cans without pop-tops ? I didn't know they ever made such a thing. I though it only came in bottles before the pop-top. StuRat (talk) 23:33, 28 January 2014 (UTC)[reply]
Here is a photo [14] of the two triangular holes in the steel can that had to be made with the tool linked to above. The other end, lifted off the crowns on bottles. Oh happy days, one could fill up the Pontiac, grab a coke and still get change from a five dollar bill.--Aspro (talk) 00:08, 29 January 2014 (UTC)[reply]
Having just reread what I wrote, I wondered if my memory was playing tricks on me -but in my mind's eye I can still see those five dollar bills in my hand. So I looked it up. http://www.google.com/url?q=http://oregonstate.edu/cla/polisci/faculty-research/sahr/gasoline.pdf&sa=U&ei=tEfoUsmwFMbR7Ab71IGABQ&ved=0CDsQFjAF&usg=AFQjCNFcGVDyqTbHh1wdORRrFPn9le_yJQ Yes, gas was less the 30 cents a gallon, so one could fill up the auto for the week ahead and get a coke for oneself and my seat-cover and still get change from a five dollar bill. And the coke came in a steel can that we had to open with one of those can openers--Aspro (talk) 00:47, 29 January 2014 (UTC)[reply]
I'm familiar with that method of opening cans, as I've used it on cans of oil (although the air hole doesn't need to be nearly as large). I've just never seen it applied to cola. (I wonder how many absent-minded mechanics poured their Coke into the car engine instead of motor oil.) What would be the advantage of that kind of can over a bottle ? Easy opening pop-tops seem to be the main point of cans, to me. StuRat (talk) 00:57, 29 January 2014 (UTC)[reply]
I've had one of those all my life, and have only ever used it on tomato juice cans. I have no idea why every other beverage around here has some sort of "hands-only" design. Makes even less sense considering tomato acid reacts with the metal after opening, and it's suggested to put it in a glass or plastic pitcher. InedibleHulk(talk) 01:07, January 29, 2014 (UTC)
Of course back when you could fill up your Pontiac for $5, the gas consumption would have been so appallingly bad that you wouldn't get much further than a modern car does on $30...but that's another story! SteveBaker (talk) 21:27, 29 January 2014 (UTC)[reply]
You'd probably also need a very hot fire and a bunch of cans. Having a very hot fire in a creosote-laden chimney isn't smart. Best to just buy one of these "logs". I can vouch for them. InedibleHulk(talk) 00:16, January 29, 2014 (UTC)
I can't find an official ingredients list of that product online, but some of my linked discussions above say that they contain aluminum in some form. It should say on the package. SemanticMantis (talk) 15:17, 29 January 2014 (UTC)[reply]
It might. I burned my last package before Christmas, right after the log. In any case, the recipe is certainly different from beer cans, and it burns at a much lower heat. Cans are cheaper, though. For now.InedibleHulk(talk) 23:36, January 29, 2014 (UTC)
Cold hands feeling like they're pulsating
When I was kid at school in the UK in the winter, we had to play football which I had no interest in. My hands would become exceedingly cold and eventually I would feel this very unsettling, exaggerated pulsating. It felt like I should be able to see the pulsating but thankfully did not. Is this usual? I would never allow my hands to reach anywhere near that temperature now so I don't know (or much mind) whether it still (would) happens. --78.148.110.69 (talk) 20:20, 28 January 2014 (UTC)[reply]
We don't give medical diagnosis here on Ref Desk and this is what your really asking. However, I can give you some pointers that you can run by your General Practitioner for reassurance. Yes, it is common if the pulsation is in the wrist and you are terribly cold. In less server weather extremes it might get diagnosed as Carpal tunnel syndrome. It is worth running by your GP because as though you don't suffer from it now, one of your children or grandchildren might suffer from it and you can inform their parents that is they are not complaining about a trifle. Good gloves, jumper etc mitigates to discomfort – but the condition first, has to be recognized as real, so that the the school allows extra clothing on the football field.--Aspro (talk) 21:16, 28 January 2014 (UTC)[reply]
It is not a medical question! I absolutely will not make an appointment to see my GP (free on the NHS but that doesn't make it okay to waste their time) to ask him about a sensation I experienced 14/15 years ago! If I pricked myself sewing and a drop of blood formed on my finger, would it be a medical question if I asked about its colour or why it clots? To clarify, it was the main body of my hands, not my wrists, and the grass field was frozen which is pretty extreme weather to be standing around outside in shorts and a crappy rugby jersey. 129.215.47.59 (talk) 17:15, 29 January 2014 (UTC)[reply]
I'm not asking for a medical diagnosis; I want to know of human physiology. If I had the mind I have now, I'd have told the teacher to speak to my lawyer (an idle thread) and have gone inside. I think the temperatures my extremities experienced were beyond normal. No-one can "force" me now to stand outside in inappropriate clothing at the age of 29. Also, it wasn't my wrists but the flesh of my hands in which I felt this. If I'm the only one to report this then fine, but I suspect others know what I've experienced and maybe understand why. Maybe the cold affects pressure sensors in this way. 78.148.110.69 (talk) 22:07, 28 January 2014 (UTC)[reply]
RE: 'No-one can "force" me now to stand outside in inappropriate clothing at the age of 29' ... just don't join the military. School coaches aren't the only sadistic people. StuRat (talk) 23:37, 28 January 2014 (UTC)[reply]
I've just realised that by "football" the OP probably means that strange sport where you aren't allowed to do anything with your hands, except letting them just hang there to get frozen. Though Bugs's suggestion might be on the right track. HiLo48 (talk) 23:47, 28 January 2014 (UTC)[reply]
What? You realized that by football, they meant a sport where they use their feet? WTF is your point? I'm a fan of football, not soccer, but your response makes no sense to me. --Onorem (talk) 23:55, 28 January 2014 (UTC)[reply]
Well, it's obvious that not being allowed to do anything with one's hands as part of the game is going to make this problem worse. Where I come from "football" means a game with big involvement of both the feet and the hands. My statement was true. I didn't realise initially that the game in question was probably "soccer". HiLo48 (talk) 00:01, 29 January 2014 (UTC)[reply]
The OP geolocates to, and specified, the UK - hence, football would equate to soccer. Obviously, the hands are required in certain parts of the game: goalkeeping, throw-ins, etc. I was just wondering if the OP had tried tucking his hands, or if he found that impractical. ←Baseball BugsWhat's up, Doc?carrots→ 00:22, 29 January 2014 (UTC)[reply]
When you're cold, blood vessels near exposed skin contract more than in warmer parts. The pulsing is your blood squeezing through tighter spaces there. At this point, you're probably close to or at frostnip, then frostbite. InedibleHulk(talk) 01:19, January 29, 2014 (UTC)
You get some leeway time between numb and serious tissue damage. Not long in very cold weather, probably a fair window in England. But it's best not to wait, because thawing hurts a lot more than freezing. InedibleHulk(talk) 02:40, January 29, 2014 (UTC)
A key question would be whether it was above or below freezing. Is it possible to get frostbite if the temp and the wind-chill are both above freezing? Also, would being "interested" in the game help the OP stay warmer? ←Baseball BugsWhat's up, Doc?carrots→ 02:59, 29 January 2014 (UTC)[reply]
Can't get frostbite above zero, but the vessels will still contract somewhat at whatever temperature a body decides is too cold. Gotta figure an interested player will play harder, and that'll warm him up. Thinking about anything intently should create some warmth in the brain, but the humanly imperceptible and virtually insignificant kind. InedibleHulk(talk) 03:38, January 29, 2014 (UTC)
Just passing by. Anyway, a good advice : if you smoke, quit NOW ! (are you aged 29 ? are there any such cases in your family ? did you hear of Raynaud's syndrome ? ). But I must stop, of course ...Good luck to you Arapaima (talk) 09:10, 29 January 2014 (UTC)[reply]
Thanks guys but I don't smoke and it really isn't a medical issue. My extremities do not discolour like that and I'm not prone to it. It was just poor child care (I probably should have been sent to run laps around the field but didn't think to do this myself because I was a stupid kid) and I still think I was experiencing a normal phenomenon. I will scour the Internet for answers and will report back if I find anything. 129.215.47.59 (talk) 13:35, 29 January 2014 (UTC)[reply]
Hello Learned Ones ! I am following my program "Do now what you never had time to do in the past years" & just watched Friends (season 10) 11th episode "The One Where the Stripper Cries" (Feb. 2004) . I was flabbergasted at Danny DeVito 's performance as a distorted and aged stripper. I also brooded (as a M.D., & from a medical point of view) about his legs problem : hidden by the pantaloon he kept on, they seemed to me very thin, paralysed, & not flexing, maybe held up by stilts, while his torso seems about normal. WP does not give any hint about his ailment. Can somebody tell me what it is ? Poliomyelitis sequel ? Neural horse-tail malformation ? General osteo-formation disease ? Anyway, hats down in front of the man's stamina & mind power ! Thanks beforehand for your answers. T;y. Arapaima (talk) 09:02, 29 January 2014 (UTC)[reply]
I am an instructor of a bioinformatics course at the University of Minnesota. We write Wikipedia articles each year on human genes of unknown function for which there are usually only stubs at the outset. I forwarded a message from someone going by "Boghog" (Boghog (talk) 17:35, 13 May 2013 (UTC) asking me to contact him so that I could ensure my students' pages are more compliant with the format of other Gene Wiki articles. I'm not sure how to contact him but perhaps you could help me do this. He gave no email address. Thanks!
You can post a message for him at User talk:Boghog (click on the "New section" tab and enter an appropriate header for your message). This sort of question is really more appropriate for the Help Desk (but there's nothing wrong with asking it here). Tevildo (talk) 20:43, 29 January 2014 (UTC)[reply]
Bed rest
What's the minimum required dose of non-bedrest to prevent permanent damage? (On Earth). The nasa bed rest study apparently causes permanent damage. 12.196.0.56 (talk) 22:20, 29 January 2014 (UTC)[reply]
Pending clarification, one big problem with being bedridden is getting nasty skin problems, which can lead to further infection, etc. If you're interested in that, see bed_sore#Prevention, and the references therein. Also, the US government has a comparison of preventative guidelines here [15]. SemanticMantis (talk) 23:28, 29 January 2014 (UTC)[reply]
Why is octanol thicker than octane? At least by boiling point, if not actually thickness. Long enough alcohols become solid even at body temperature. Is there like a gel phase or do they just suddenly freeze? What would it be like to swallow or gargle various pure alcohols? I'm not going to try it (okay, I put 70% isopropyl in my mouth once - My palate instantly shriveled like a prune). Even if it'd just be shriveling and pain at least tell me what the consistency would be like. — Preceding unsigned comment added by 12.196.0.56 (talk) 22:41, 29 January 2014 (UTC)[reply]
Standing water in my workshop not freezing at below 32 degrees
I live in detroit and my workshop as i measured today clocked in at around 24 degrees fahrenheit, but all of the standing water in cups and metal buckets that were there overnight were not ice. I do not think it has anything to do with pressure as detroit is slightly above sea level i think, and the decrease in pressure would seemingly effect the freezing point in the opposite direction, though maybe I am wrong.
I used an infrared laser temperature reader so i think the readings are pretty accurate, i measured the containers and the water itself and they were the same temperature.
The only other variable i can think of is that because the water was from the tap, that some minerals or chemicals are effecting the freezing point.
That's not cold enough for water with salt or alcohol in it to freeze. Have you used either of those in your containers lately? InedibleHulk(talk) 01:42, January 30, 2014 (UTC)
Actually, according to that source, "Any foreign substance added to the water will cause a freezing point drop. For every mole of foreign particles dissolved in a kilogram of water, the freezing point goes down by roughly 1.8°C". InedibleHulk(talk) 01:44, January 30, 2014 (UTC)
There was no ice or alcohol in it, fresh water that was sitting in a metal pail, and a few in coffee cups. I guess my shop is pretty dusty so maybe the water is really full of dirt and stuff.
I suggest you calibrate your temperature reader. Put some ice out in a plate, and wait for it to start melting. At that point it will be 32 degrees F. Measure its temperature, and see if you get a temperature below 32 degrees. If so, the device is inaccurate. μηδείς (talk) 01:56, 30 January 2014 (UTC)[reply]
Delta Dagger, cont'd
As far as I know, the F-102 Delta Dagger had never seen actual combat in its intended role, which was that of a supersonic interceptor for use against bombers -- instead, it was employed in Vietnam as an escort fighter (unsuccessfully) and for ground attack (with surprising success). So, the only data that could indicate whether it would have performed well in its intended role comes from training combat exercises like the William Tell air-defense exercise (especially ones with live-firing of missiles); however, the article doesn't include this data, nor any links to it. Where can I find the data? (If you want to know, it's that "documentary" again -- what it asserts is that the Deuce was a piece of junk and a total waste of taxpayer money, whereas I'm trying to prove that it would have made a good interceptor, but it just wasn't designed for anything else.) 67.169.83.209 (talk) 02:01, 30 January 2014 (UTC)[reply]
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