Wikipedia:Reference desk/Archives/Science/2013 July 4

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July 4[edit]

Colds and bacterial infections[edit]

Why do many bacterial infections occur at the same time as or straight after a cold and vice versa? Is it just because the immune system is weakened? Clover345 (talk) 12:14, 4 July 2013 (UTC)

It's a myth that these secondary bacterial infections are commonplace: This document says that: "The common cold rarely leads to secondary bacterial infections that require antibiotic treatment." - couldn't find details of why secondary infections happen though. SteveBaker (talk) 14:04, 4 July 2013 (UTC)
I read that as being equivalent to "The common cold regularly leads to minor secondary bacterial infections but they rarely require antibiotic treatment." Our article on common cold says: "Secondary bacterial infections may occur resulting in sinusitis, pharyngitis, or an ear infection. It is estimated that sinusitis occurs in 8% and an ear infection in 30% of cases." Dbfirs 20:47, 4 July 2013 (UTC)
I've noticed that mouth ulcers often occur after a cold, and this is attributed to a weakened immune system [1]. The Free Dictionary's Medical Dictionary says: "Colds make the upper respiratory system less resistant to bacterial infection. Secondary bacterial infection may lead to middle ear infection, bronchitis, pneumonia, sinus infection, or strep throat." [2] I'm not sure whether this is because of a weakened immune system or just the inflammation caused by the cold. Dbfirs 07:34, 6 July 2013 (UTC)

Boiling water in a kettle[edit]

Which would use more energy? 1) Boiling 500ml of water from room temperature and repeating; or 2) Boiling 1 litre from room temperature. Thanks. (talk) 13:05, 4 July 2013 (UTC)

This has the appearance of a homework question, and our policy is not to do people's homework for them. Looie496 (talk) 13:10, 4 July 2013 (UTC)
In a real-life scenario or in a imaginable scenario where you don't have to heat the pot and this doesn't lose heat at all (that means, all heat gets transfered directly to the water without loss)? Try to think about the first case, what would be more efficient? OsmanRF34 (talk) 13:20, 4 July 2013 (UTC)

I guess I'm flattered you think this is homework - it means I phrased the question well. It is not homework - I don't do homework since I'm not in school. And I'm talking about a real life scenario. So I boil 500ml and then boil another 500ml immediately after (I suppose it matters if I wait before boiling the second one) OR I just boil the 1 litre. (talk) 13:29, 4 July 2013 (UTC)

I don't believe homework questions are well worded or well conceived. Normally, they try to exclude lots of constrains that matter in real-life and somehow have hints to the answer desired. OsmanRF34 (talk) 14:31, 4 July 2013 (UTC)
If your kettle is large enough to boil one liter at once, it's almost certainly more efficient to do it in one go. Your heat loss into the environment is a function of temperature and surface area, and with two times 500 ml, you will still have the same surface of the kettle that heats up and loses energy, and you also have a larger water surface. But you should be able to find out with a simple experiment. Just do it and time it. Standard electric kettles are either on or off (and you can hear/see when they auto-shut-off activates), so energy use is (modulo very small effects) directly proportional to time. --Stephan Schulz (talk) 13:52, 4 July 2013 (UTC)
Thanks, Stephan! I didn't think of that experiment. Does that mean that the amount of current passing through those heating rods in the kettle is the same as long as the kettle is switched on? (talk) 15:25, 4 July 2013 (UTC)
Yes, a standard kettle will have a nearly constant current draw (when the coils heat up, resistance goes up a little bit, but that is a very minor and transient effect). Since resistance is nearly constant, and Voltage is constant (modulo brownouts ;-), the kettle will always draw nearly the same current, and use nearly the same power. --Stephan Schulz (talk) 17:02, 4 July 2013 (UTC)
Also, if your concerned about efficiency, boil it with a lid of some kind on it. It should come to a boil faster than if it's open to the air. ←Baseball Bugs What's up, Doc? carrots→ 15:23, 4 July 2013 (UTC)
Better still, pump all the air out of the kettle and the water will boil with out the need to even switch the kettle on.--Aspro (talk) 21:16, 4 July 2013 (UTC)
For certain values of "boil", yes. --Carnildo (talk) 08:53, 5 July 2013 (UTC)
Look at it like this: The energy to consumed in raising the temperature of the water is the same, no matter how you do it. So all we're concerned about is losses in the system. Since kettles don't make much sound, emit magnetic fields, glow or anything like that - we can assume that almost all of the electrical energy goes into making things hot. The water, the kettle and the surroundings (because kettles aren't generally well insulated). We can ask where the energy that didn't go into heating the water went. If we consider two experiments (boiling two half-liter loads and boiling one full-liter load) - in each case, the kettle is at the ambient temperature at the start and close to 100C at the end. So the amount of energy residing in the kettle is the same in both cases. So the only difference is in the heat lost to the environment.
OK - so Isaac Newton discovered that the rate of temperature loss is proportional to the temperature difference between the hot object and the environment. So the area under a graph of the temperature is a measure of the energy loss...right? OK - so let's imagine that the kettle can heat the two half-liter loads in the time it takes to heat one full load...just as a hypothetical. If we plotted the graph of temperature against time for both experiments, we'd get either two complicated curves that go from ambient to boiling point - or one that goes to the same temperature over twice the amount of time. If we took the graph from the first experiment, cut them into one second-wide strips and interleaved them - we'd make the same graph that we got from the second the amount of energy lost to the environment would be identical in the two cases.
However, there is a difference. At the end of the first half-liter load, the kettle itself is still hot. So when the water is added, the temperature of kettle+water will be a little higher than ambient. So the second half-load should heat up faster than the first half-liter. The energy consumption from doing that will be a little less because the slightly faster heating rate - that means that a little less energy will be lost to the environment.
So I think that it will require a little less energy to heat two half-loads than one full load...but not by much.
There was a question of whether the heating element produces more energy at different temperatures. I don't think it affects anything in the above discussion - but I think the idea that the change in resistance of the element with temperature is negligable is incorrect. Energy consumption is proportional to the resistance of the element. Higher temperatures produce more resistance - which means that more energy can be delivered at constant voltage. Electrical_resistance#Temperature_dependence says that this increase is around 0.3% to 0.6% per degree for most metals - so over maybe 80 to 90 degrees of increase, the element will consume maybe 50% more electricity (and heat the water 50% faster) near to boiling point than at room temperature. It was previously suggested that this effect would be negligable - but clearly it's not.
SteveBaker (talk) 15:29, 5 July 2013 (UTC)

Well you all are discussing about electric kettle, how about gas kettle? The kettle pot that you fill with water and put above flame? (talk) 02:09, 6 July 2013 (UTC)

Same deal - the amount of heat loss is basically the same if the total time to boil an entire liter is the same either way. Just as my analysis above suggests, you can probably get the work done a little faster when you boil two half liters because the kettle itself is already hot when you fill it for the second time. SteveBaker (talk) 04:55, 6 July 2013 (UTC)

Putting an aspirin on the gum[edit]

Some people put an aspirin on the gum when they have toothache, is this practice backed by any publication? It's clear that even our skin would absorb some chemicals placed on it, but would the gum absorb even more? OsmanRF34 (talk) 13:28, 4 July 2013 (UTC)

Google works. --Jayron32 14:07, 4 July 2013 (UTC)
This link from that same google search states "but never put aspirin against the gums near the toothache, as this may burn the gum tissue". --Jayron32 18:34, 4 July 2013 (UTC)
It works in what sense? It outputs lots of 'natural remedies' results, unrelated results like gum aspirin, and relevant results for someone searching for a topical aspirin or aspirin gel, but I was asking for the usability of a normal aspirin on the gum. OsmanRF34 (talk) 14:26, 4 July 2013 (UTC)
Individual reactions to aspirin can vary. Some cannot ingest it, due to its tendency to inflame the stomach lining. It can also act as a blood thinner, which you may not want. If you've got a recurring toothache, you should see a dentist. ←Baseball Bugs What's up, Doc? carrots→ 15:20, 4 July 2013 (UTC)
Castoreum and other beaver products, rich in salicylates, have been used as topical painkillers since Roman times, as well as in many places in native North America. Wnt (talk) 00:17, 5 July 2013 (UTC)
I see no evidence for this claim, which is both dubious and unconvincing in this context (since historical uses of castoreum have included so many things, including emotional distress). -- Scray (talk) 14:50, 5 July 2013 (UTC)
Beaver mentions some sources, though most of them are not readily accessible, excepting [3]. I'm not sure if you're disputing topical salicylate, though there might be some question as to how much is actually just reaching general circulation [4] Wnt (talk) 15:19, 5 July 2013 (UTC)

wild animals and spicy food[edit]

Do any animals in the wild have a taste for spicy plants such as hot peppers, mustard-type plants and horseradish, ginger, onions, garlic, etc? Or do they all avoid these plants because they are an irritant?— Preceding unsigned comment added by (talkcontribs)

I don't have a source on this because I read it a long time ago, but although they don't have a taste for it per se, birds are unaffected by spicyness. I read it in a book about leaving out stuff for birds to eat; coat it in spicyness to keep mammallian scavengers away, but the birds won't even notice. (talk) 15:19, 4 July 2013 (UTC)
We hear about "grain fed cattle" as the common type and "grass-fed beef" as a pricy gourmet choice, but cows are happy to eat onions and garlic if they find them, though the milk then tastes of onion and garlic. Mad scientists are experimenting with feeding garlic to cows to reduce cow-flatulence which supposedly causes global warming: [5]. Cows will eat so much onions that they can get sick and even die. Horses and goats eat onions too: [6]. Cows do not immediately eat turnips growing in a field, but learn to like them, especially after freezing weather has increased the sugar content of the tops. This source also implies they will eat radishes: [7]. Comments at this site suggest that turkeys and parrots love very hot peppers, but deer avoid them. Here's a video of a cow eating pickles and hot peppers. Edison (talk) 16:00, 4 July 2013 (UTC)
Birds and primates will eat hot foods. Spicy foods often have attractive red colors visible to trichromatic birds and mammals. Dogs and cats and hooved mammals are neither attracted by their colors nor adapted to eat spicy foods, which may be poisonous. Humans have large livers adapted to handling plant alkaloids and so forth. μηδείς (talk) 17:34, 4 July 2013 (UTC)
The link above mentions this, but for those who haven't clicked it, one of the reasons birds ead "spicy" peppers is because they don't sense capsaicin like humans and other mammals do. So when a bird eats a habanero, it's not really percieving any spicyness - for the bird it's somewhat akin to a human eating a bell pepper. So it would be misleading to say that birds eating spicy peppers indicates that they like spicy food, because to them it's not spicy. -- (talk) 18:56, 4 July 2013 (UTC)
I remember seeing a video on YouTube (which doesn't seem to be there any more, so you'll have to take my word) of a gull reacting negatively to a piece of bread that was spread with English mustard. It attempted to swallow the bread twice, only to very quickly regurgitate it, with much head-shaking. So it would seem that some birds can sense some types of spice. --Kurt Shaped Box (talk) 19:33, 4 July 2013 (UTC)
Mustards get their pungency from sulfur compounds, thiocyanates. Capsaicin is an alkaloid, but not a sulfur compound. Gulls are not notable for being attracted to red fruits like peppers. μηδείς (talk) 21:42, 4 July 2013 (UTC)
For what it's worth, gulls seemingly don't like wasabi either. --Kurt Shaped Box (talk) 22:09, 4 July 2013 (UTC)
Do the rest of you really put all these things in the same category? Peppers, horseradish, and ginger are "hot"; mustard, onion, and garlic are "spicy" but not "hot" (there's "hot mustard" but it has horseradish added). That's exactly why we need a separate word for the hot spices. --Trovatore (talk) 21:46, 4 July 2013 (UTC)
I might take issue with the horseradish accusation - see English Mustard. The near-identical appearance of English mustard and French's mustard is a frequent source of entertainment when unwary American tourists first encounter the former. Tevildo (talk) 22:13, 4 July 2013 (UTC)
Yep, I'd definitely say that English mustard is 'hot'. --Kurt Shaped Box (talk) 22:20, 4 July 2013 (UTC)
It's not just English Mustard. In the U.S., the mustard they serve in some Chinese restaurants is a tad piquant as well. --Jayron32 22:32, 4 July 2013 (UTC)
But "piquant" is not the same as "hot". "Hot" is a specific sensation involving thermoreception; "piquant" doesn't really seem to be any more specific than "spicy", as far as I can tell. --Trovatore (talk) 22:36, 4 July 2013 (UTC)
See Understatement. Come back if you have any further questions or do not understand what that article has to say. --Jayron32 22:41, 4 July 2013 (UTC)
If you're talking about the mustard I think you are, it has horseradish in it. --Trovatore (talk) 22:44, 4 July 2013 (UTC)
Nope. --Jayron32 22:53, 4 July 2013 (UTC)
Colman's Mustard contains "Water, Mustard Flour, Sugar, Salt, Wheat Flour, Spice, Citric Acid, Stabiliser (Xanthan Gum).". No horseradish. Tevildo (talk) 23:14, 4 July 2013 (UTC)
Better still, Colman's Mustard Powder contains _only_ mustard flour. Try putting that on your hot dogs. :) Tevildo (talk) 23:15, 4 July 2013 (UTC)
As hinted at by μηδείς, Pungency is evidently used for this purpose in some scientific publications. That said, it would be interesting to know what languages do have an established word. I know Malay and Indonesian do as I think does Thai. And I wonder if words like picante in Spanish is closer in meaning to piquant in English or "hot". Nil Einne (talk) 22:57, 4 July 2013 (UTC)
  • As I understand it, the "hot" sensation comes from stimulation of TRPV1 receptors, and capsaicin, piperine (from black pepper), mustard, ginger, etc all contain chemicals that activate those receptors. Looie496 (talk) 22:54, 4 July 2013 (UTC)
There are at least three deeper issues here. The fundamental epistemological issue is that humans even at the pre-scientific level perceive and categorize sensory differences long before they (if ever) explain and categorize them scientifically. The basic colors were named and categorized as warm and cool, bright and dark, long before tint and saturation were explained in scientific terms. The same with tastes such as bitter, which was known long before it was explained by the presence of basic ions. The second issue is cultural, that humans have learned to add various flavor-enhancing substances to foods; substances which they are aware of and value highly. Third is linguistic, especially that at a pre-scientific level, there is leeway and the option of emphasis. Many languages lack a specific name for brown, call pinks and oranges and purples after flowers and fruits, and identify red with "colorful" (Sp. colorado) or "beautiful" as in Russian krasnyj/krasiwyj. Yet Russian distinguishes as strictly between what we call baby and royal blue as much as we separate yellow and green, and lacks a general term "blue" that covers both tints.
Hence, in English we have the concept spice or spicy, which is broader, and covers any flavor enhancer that does not readily fall into sour, salty. or sweet. Cinnamon, bacon, cheese, and garlic can be spicy without our understanding why specifically. And hence we can categorize them with leeway. Foods like pepper that we only later learn stimulate heat-receptor nerve cells become to English speakers the stereotypical spices. Yet spicy is a broader term than hot in the way that colorful is a broader term than red. Spicy used loosely in English will translate to piquante in Spanish where it means "hot" in the English sense, but doesn't cover paprika, saffron, or cinnamon. Bilinguals learn these traps. Eventually, when a full scientific vocabulary is developed, it becomes possible to qualify translation from language to language exactly. μηδείς (talk) 04:01, 5 July 2013 (UTC)
I just watched epidoe 8 of season 4 of Breaking Bad, which has a long segment in Spanish, where one gangster goes on at length using various words for spicy to describe a Chilean's cooking, then praises it specifically for being "hot" (piquante & picoso) in the way Mexicans like it. μηδείς (talk) 23:41, 5 July 2013 (UTC)
I believe the reason hot/spicy plants developed in the first place was to keep animals from eating them (mainly insects). However, those animals/insects which were more tolerant of this continued to eat them and survive and pass down their genes, leading to an arms race of spicier plants and animals/insects which could still stand them. So, there should be some animals or insects which can at least tolerate spicy plants. This isn't the same thing as preferring them, but it might make sense to prefer spicy plants, if you are the only animal/insect which can eat them, and will thus have less competition there. StuRat (talk) 04:40, 8 July 2013 (UTC)

Video on race and intelligence[edit]

I watched the first 20 minutes of this video. Familiar with the situation from the viewpoint of Boas and Gould and those they criticize, the video's author makes no obvious mistakes, although his POV is clear. I am not about to listen to the whole video. This page is not the forum to debate the claims. But readers should not assume that this being closed is weight in favor of its falsehood. μηδείς (talk)

Gould's flaws are well-known, but I wouldn't say this fact demolishes non-racist world views. Gould's is barely a seminal work. I still wait to see a race=>IQ argument that defines races and IQ, explains how you measure belonging to one race and how you measure IQ (independent of environmental factors). The parts of the video that I saw were of a rather convoluted nature, presenting evidence out of nowhere, confusing up being equal to being the same, attacking what an undefined group of people, called "they" think or want. OsmanRF34 (talk) 11:29, 5 July 2013 (UTC)
Well I sometimes do statistics using fuzzy measures so precise definitions don't bother me too much, but what's there so far provides no evidence of any significant difference due to genetics between countries. Deprivation is easy to understand but the thing I have really been surprised by is the enormous effect people's expectations and peer pressure have on performance. Dmcq (talk) 14:02, 5 July 2013 (UTC)
I'd like to see some of those white supremacist degenerates take an IQ test constructed by someone like the Maasai people and see how well they would do. ←Baseball Bugs What's up, Doc? carrots→ 16:35, 5 July 2013 (UTC)
Yep, an IQ test based in something like distinguishing linguistic tones would do the trick. It would come out that Africans are the most intelligent, followed by Chinese and Vietnamese, I suppose. "If you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid." OsmanRF34 (talk) 16:45, 5 July 2013 (UTC)
As an aside, I am fairly certain that the most complex tonal language systems are found in SE Asia, not Africa. See Tone_(linguistics)#Number_of_tones. μηδείς (talk) 03:06, 6 July 2013 (UTC)
Could you not let your hate of white supremacists spill over to silly assumptions about the people who set up IQ tests thanks. Many in the field can be criticized but they are on both sides. Whenever people start off knowing 'the truth' and are determined to prove it and are unwilling to accept contrary evidence then they are not scientists but demagogues. Dmcq (talk) 10:54, 6 July 2013 (UTC)
I agree, criticism of the video here has been mostly people bashing race realists irrationally. No one really has any other criticism towards the video.— Preceding unsigned comment added by (talkcontribs) 18:34, 6 July 2013‎
Race realists? Great, immediately after I say about people who 'know the truth'. Dmcq (talk) 10:28, 7 July 2013 (UTC)
Race realist = short form of rac (really) ist?OsmanRF34 (talk) 13:10, 7 July 2013 (UTC)
Given that in the first 90 seconds, the speaker admits not to know what Pe El Oh Es is, and that he wrongly claims that this study is published in the non-existing "PLOS Psychology", when it actually appears in PLOS Biology, I would not give any weight to the video. --Stephan Schulz (talk) 08:10, 7 July 2013 (UTC)