Wikipedia:Reference desk/Archives/Science/2016 February 10

= February 10 =

io photographs
When everyone was all excited about the New Horizons space probe reaching pluto I remember seeing photos of one of Jupiter's moons called io. 2 of these photos stood out to me. They were possible infrared photos or something similar. They appear to be black and white. You could see little bright spots/mushroom clouds from the volcanoes erupting. Where did these pictures go?! I can't find them on google images nor can I find them on wikipedia. Can anyone help me find them? 199.19.248.82 (talk) 00:18, 10 February 2016 (UTC)


 * Our article on Io (moon) links to many great resources, including:


 * Io at the NASA Jet Propulsion Lab Photo Journal archive
 * New Horizons Io photo catalog from Johns Hopkins Applied Physics Lab
 * Io photographs from the Galileo mission, archived at University of Arizona's Planetary Image Research Laboratory
 * Nimur (talk) 03:02, 10 February 2016 (UTC)


 * This might be the one you're thinking of, although the quality is not great. The bright spots are indeed volcanoes. Commons:Category:Photos of Jupiter system by New Horizons and commons:Category:Volcanoes of Io have some more images. Smurrayinchester 13:38, 10 February 2016 (UTC)

hops as a preservative
The beer article mention that hops acts as a preservatives a few times. Which chemical in hops exactly is providing the preservative effects?

The beer article also says "the acidity of hops is a preservative", so would other acids work as well? Johnson&#38;Johnson&#38;Son (talk) 08:06, 10 February 2016 (UTC)


 * I notice that of the 2 references ([61} & [62]) used for that statement, the first no longer leads to relevant material and the second leads to the abstract of a possibly relevant article but does not mention the preservative property explicitly in the abstract (the property of aiding head retention is not quite the same thing).
 * From my own informally acquired knowledge of brewing, the preservative effect was the reason for the introduction of hops in the mediaeval period, after which the taste effect became appreciated, but in the modern era – with better control of hygiene in the brewing process – the preservative effect is less relevant and the effects on taste and other factors (e.g. mouthfeel) predominate.
 * I have a range of books about brewing at home which might contain the answer re hops, but will not be able to consult them until Thursday at the earliest. As for using "other acids", I'd assume it possible that other non-hop adjuncts formerly used such as sweet gale (Stonehenge Brewery still uses this for one seasonal beer) may have had preservative as well as flavouring effects. If however one was to use non-plant sources, I personally would no longer regard the resulting beverage as "beer" :-) . {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 15:16, 10 February 2016 (UTC)
 * There may be two effects at work here, and hops role may be more in one than the other. The first is that hops may actually act as a preservative, that is it may chemically prevent spoilage.  The second effect is that hops may mask spoilage by its strong flavor.  That is, you taste the hops rather than the spoilage in the beer.  this reference for example notes that herbal mixtures (such as hops, but also other herbs and spices known as Gruit) "mask unpleasant spoilage notes".  One of the characteristics of India pale ales, or IPAs, is their extremely high hop content, which covered the "skunky" or "stale" taste of beer shipped from Britain to India on long overseas voyages.  This beer blog notes "High hop levels can preserve a beer’s flavor in two ways: they have a limited ability to protect beer from spoilage by some microorganisms, and, more importantly, their bitterness can mask stale flavors." (bold mine).  Several other sources about IPAs note the use of larger quantities of hops than normal to mask staleness, spoilage, or undesirable flavors.  -- Jayron 32 15:47, 10 February 2016 (UTC)


 * This reference, says that Primary Alpha Acids Humulone, Cohumulone, Adhumulone have an antiseptic effect, especially against Gram positive bacteria. DuncanHill (talk) 15:56, 10 February 2016 (UTC)
 * EC: If you scroll down your original link to hops, there's a subheading about chemical composition, which on expansion isn't simply about taste. It's the release of Alpha_acid and Beta_acid in the fermentation process that acts as a preservative. I think other acids could act as a preservative in beer, but then would it still be beer per se, as the hops are an integral part of the process. When fermenting wine Sorbic acid can be added as a preservative, so you could put some of that in fermenting beer as a preservative I guess. I'm not sure how that would affect the rest of the fermentation process or taste though. Mike Dhu (talk) 16:16, 10 February 2016 (UTC)


 * As far as other acids working, yes, anything that moves the pH outside the range a particular bacteria likes will act as a preservative to prevent that particular bacteria from growing. However, there are acidophile bacteria that may thrive in those extremes, so keeping those out is also important.  Of course, the acid may also kill the yeast, so could only be added after the brewing process is complete, and people won't like extremely acidic beer either, so it would need to be later neutralized.  Thus, there are easier ways to preserve it with modern technology.  StuRat (talk) 17:29, 10 February 2016 (UTC)


 * I will point out that hops is the closest biological and linguistic relative of hemp, (i.e., Cannabis), and that the two words are either cognates or very closely related wanderworts.  See also soma, which seems to be some sort of brewed drink, perhaps from poppies or hemp. μηδείς (talk) 02:56, 11 February 2016 (UTC)


 * The berries of the "chequer tree" Sorbus torminalis were widely used in England to flavour beer before the arrival of new-fangled hops (in the 15th century). Our article describes them as "usually too astringent to eat until they are over-ripe". I don't think I've ever seen one, but they're related to the rowan which certainly has acidic-tasting berries. Alansplodge (talk) 17:50, 11 February 2016 (UTC)
 * The old recipe, imho tasted much better than hops. Barbara Tuckland in "A distant mirror" suggests that the introduction of hops of started in the 14th century, and by putting down peasant rebellions with lethal force to overcome the resistance to hops. Star Lord -   星爵 (talk) 06:00, 15 February 2016 (UTC)

Unknown bird
Can anyone help me identify the bird shown? The photo was taken in the Ngorongoro crater, in Tanzania, in January. Thanks.. --Phil Holmes (talk) 13:53, 10 February 2016 (UTC)


 * Rufous-tailed weaver. Mikenorton (talk) 13:58, 10 February 2016 (UTC)

That's the chap. Thanks for your help. --Phil Holmes (talk) 15:20, 10 February 2016 (UTC)

water temperature and baby bath
If the baby bath water feels at all warm to the touch (hand or elbow) does that necessarily mean that its temperature is above 37C, since the human temperature is (approx) 37C? Or can the water be 32C, still warm to the touch, because there is a difference between how we sense temperature on our skin and our core body temperature? If the water is really 32C (as indicated by the thermometer), will it necessarily feel 'cold' since my core temp is 37C? I'm trying to understand if there is a difference between core body temperature, and our sensation on the skin of warm/cool. Thanks if you can point me to a credible info source. — Preceding unsigned comment added by 94.210.130.103 (talk) 20:25, 10 February 2016 (UTC)
 * Our article on thermoregulation covers some of this. Your specific questions about whether or not something will "feel cold" are going to be highly variable from person to person and at different times (as the link above suggests). Broadly speaking, we're not very good at gauging temperatures. Our article at thermoreceptor is not very detailed, but my own experience is that we seem to feel temperature changes rather than actual temperatures. Matt Deres (talk) 21:12, 10 February 2016 (UTC)


 * Yes, skin temperature is what is being compared. You can verify this yourself by cooling one hand (just go outside with only one glove, for a bit, in winter), then put both hands in water that you have verified is body temp with a thermometer.  The water will feel much hotter on the cold hand. StuRat (talk) 21:11, 10 February 2016 (UTC)


 * Notice too that babies are more delicate to the temperature. Bath water should be just above 100 F (which are the 37 C you mention) to prevent chilling or burning the baby. In case of doubt, simply use a bath thermometer. --Scicurious (talk) 00:33, 11 February 2016 (UTC)


 * Incidentally, the reason we're so poor at determining temperature by touch is that what our senses really detect is the rate at which heat flows out of or into the skin. That's a function of both temperature of the skin, temperature of the thing you're touching and the thermal conductivity of that thing.  That's why wood feels warmer than metal when both are at the same (below 37C) temperature...wood is a poor conductor of heat and metal is good, so we are fooled into thinking that metal is "colder" because the heat leaves our skin much faster than it does when touching wood.


 * StuRat's example of sensing temperature with a hand which is cold is also caused by this since the rate of heat flow into the cold hand is faster than into the warm hand.


 * Bottom line is that we simply don't have a sense that can judge temperature directly...even though we all seem to think that we do.
 * SteveBaker (talk) 15:05, 11 February 2016 (UTC)

What does the X and Y (of chromosomes) stand for?
93.126.95.68 (talk) 20:45, 10 February 2016 (UTC)


 * See X chromosome, Y chromosome and XY sex-determination system. -- Jayron 32 20:47, 10 February 2016 (UTC)


 * They don't stand for anything, that's what they actually look like: . Other than the Y chromosome, most healthy human chromosomes look something like an X, with some looking more like a U or V:  (see image 5).  The Y chromosome, on the other hand, is missing a part, and that makes it look more like a Y. StuRat (talk) 20:54, 10 February 2016 (UTC)


 * No, that's incorrect. According to our article on X_chromosome it was so-named because "...Henking was unsure whether it was a different class of object and consequently named it X element, which later became X chromosome after it was established that it was indeed a chromosome. The idea that the X chromosome was named after its similarity to the letter "X" is mistaken. All chromosomes normally appear as an amorphous blob under the microscope and only take on a well defined shape during mitosis." And according to our article on Y chromosome, that name was chosen simply because it came after "X". Matt Deres (talk) 21:04, 10 February 2016 (UTC)


 * Interesting, but I bet those temporary names would have soon been replaced, had they not turned out to physically match the appearance of each during mitosis. (To me, the more obvious terms would have been "male" and "female" chromosomes.) StuRat (talk) 21:08, 10 February 2016 (UTC)


 * The ZW_sex-determination_system also doesn't have chromosomes that look like letters, and the letters don't stand for anything there either. The other main sex-determination system is X0_sex-determination_system, but I'm not sure if the X looks like an X there or not. SemanticMantis (talk) 22:10, 10 February 2016 (UTC)


 * Your bet would be foolish. All chromosomes look like an X (during early mitosis). Why aren't they all called X according to your 'logic' then? Fgf10 (talk) 08:04, 11 February 2016 (UTC)


 * For the same reason you don't give all your kids the same name (unless you're George Foreman). Because it would obviously be confusing to call them all the same thing.  Of the sex chromosomes, only one type looks like an X and the other resembles a Y. StuRat (talk) 16:21, 11 February 2016 (UTC)

Does DEMKO approve Schuko (CEE 7/7) plugs?
I owned an old washng machine which had a Schuko plug (the "French-German compromise" CEE 7/7): among various certification labels (VDE, CEBEC, ÖVE...) there was also the symbol of DEMKO, even if Denmark did not accept Schuko plugs until very recent times. Can someone tell me why there was a DEMKO certification label on that plug?--Carnby (talk) 21:13, 10 February 2016 (UTC)
 * Yes. The Schuko plug originates in a patent granted in 1930 to a Bavarian manufacturer Bayerische Elektrozubehör AG. The company ambition, now partly realized, was to create a Europe-wide standard. It would be natural to seek individual European national approvals, especially in countries bordering Germany that are markets for German goods, at the earliest opportunity so that the approval logo could be included on the injection-moulded plug. DEMKO, the National Body for testing of electrical products sold in Denmark existed already before the Schuko patent(s) and could issue its D-Mark approval at any time. However since 1978 electrical products no longer need to carry the D-Mark for sale in Denmark. Safety note: A Schuko plug for a metal-cased washing machine is safe to use with an earthed Schuko wall socket but it creates a safety hazard if plugged into a different non-earthed 2-pole socket. AllBestFaith (talk) 13:47, 11 February 2016 (UTC)

Climate averages of Bacău
The page about the Romanian city of Bacău still has no climate averages; could someone please tell me where I can find a reliable source about climate averages for Bacău region?--Carnby (talk) 21:20, 10 February 2016 (UTC)
 * Have you tried Weather Underground (weather service)? I think they usually have this information somewhere for many places.  It's usually my first stop for weather info.  -- Jayron 32 21:23, 10 February 2016 (UTC)
 * AFAIK Wunderground does not show reliable climate averages (WMO recommends at least 30 years of daily record[ing]s)--Carnby (talk) 21:55, 10 February 2016 (UTC)
 * The Romanian Wikipedia has this at ro:Bacău, cited to the Administrația Națională de Meteorologie (which would be your best bet for further info):


 * Smurrayinchester 14:56, 11 February 2016 (UTC)

For how long bacteria and viruses can live outside of the body (not in laboratory conditions)?
For how long bacteria and viruses can live outside the body- not in laboratory conditions? For example if someone has influenza or bacteria disease and he sneezed and spread the bacteria or the viruses and they reached to the bed / table / chair etc. (the other places where people used to touch). If someone touch these places he should be infected? (People say that HIV for example is destroyed right after some seconds after it goes out of the body/ Is that true?)93.126.95.68 (talk) 21:23, 10 February 2016 (UTC)


 * It varies a lot, depending on the pathogen. Since you mentioned HIV specifically, no, that is not true. Or at least it is not generally true that the virus always is destroyed within seconds of leaving a body. Hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) can all survive outside the human body for several weeks, with virus survival influenced by virus titer, volume of blood, ambient temperature, exposure to sunlight and humidity.
 * From this study published in 2007. Here's a nice overview of virus survival in the environment, it discusses several different groups. SemanticMantis (talk) 22:03, 10 February 2016 (UTC)
 * Thank you for the information. The study is amazing. 93.126.95.68 (talk) 22:44, 10 February 2016 (UTC)

Does chlorine destroy viruses like it does to bacteria?
Can chlorine destroy viruses like it does to bacteria? If it can, what is the mechanism? 93.126.95.68 (talk) 23:00, 10 February 2016 (UTC)
 * This is a substantially complicated subject. The short answer is yes, and it varies. There are LOADS of resources if you google chlorine virus inactivation. Can you make your question more specific? Or at least convince us this isn't a homework question? Vespine (talk) 00:15, 11 February 2016 (UTC)

Yes, it can. Chlorine reacts with double bonds (see Halogenation). Bleach (sodium hypochlorite, NaOCl) works in a somewhat similar way. I won't get into how the reaction works on the molecular level, but viruses, like bacteria, contain double bonds between two carbon atoms. Chlorine reacts with those double bonds. The usual result is a carbon-carbon single bond with a chlorine atom on each carbon. Disruption of the double bonds either destroys the virus's protective coat or its ability to reproduce, or both. Roches (talk) 00:23, 11 February 2016 (UTC)
 * Thank you. I asked it just for to know if I clean an area by chlorine if it's also against viruses. Today when I clean the working surface in the kitchen the question raised in my brain. no homework at all. 93.126.95.68 (talk) 01:27, 11 February 2016 (UTC)
 * The answer is still "It depends." Some viruses have thick protein coats which require a higher concentration of chlorine to inactivate them. Generally, according to a US Centers for Disease Control study, many of the enteroviruses (among the viruses they cited were Hepatitis A, Poliovirus, the Noroviruses (implicated in outbreaks of food-borne illness), and Rotavirus) are "moderately" resistant to chlorine's disinfectant effects, compared to bacteria. However, sodium hypochlorite-based cleaners such as the "Clorox" brand disinfectants are over ten times more effective than disinfectants using alcohol, phenol, or quaternary ammonium compounds at killing both bacteria and viruses.
 * The most resistant micro-organisms to chlorine disinfection, according to this study, are the protozoa, and some of these can cause very nasty diseases - Entamoeba histolytica, Giardia intestinalis, Toxoplasma gondii and Cryptosporidium parvum were cited in particular to be both highly resistant to chlorine disinfection and to be persistent to various degrees in water supplies, with Cryptosporidium parvum being the most troublesome micro-organism found in water supplies - it caused the largest waterborne-disease outbreak ever documented in the United States, making 403,000 people ill in Milwaukee, Wisconsin in 1993. loupgarous (talk) 07:18, 11 February 2016 (UTC)

What is the physiological reason for inappetence?
In a lot of conditions, especially in cases of infections, there is inappetence. What is the physiological reason for that? (I know for example that the fever caused for destroying the bacteria and viruses). I thought that the explanation is the the body want to fight with the pathogen and the eating disturbs it, because the body needs to Invest energy in the digestion. Am I right? 93.126.95.68 (talk) 23:10, 10 February 2016 (UTC)


 * I don't think "inappetence" is an actual English word, or at least not one commonly used in medicine or biology. The usual technical term is "anorexia".


 * Unfortunately, for a lot of people, that word has become synonymous with anorexia nervosa, and in fact anorexia is a link to that article. Our article for what you want is at anorexia (symptom).  That's probably where you should start looking. --Trovatore (talk) 23:40, 10 February 2016 (UTC)


 * Indeed, inappetence forwards to Anorexia (symptom) (which is different from anorexia.--Scicurious (talk) 23:44, 10 February 2016 (UTC)


 * I'd just use the common term "lack of appetite". That's clear to everyone, except perhaps a geologist. :-) StuRat (talk) 00:20, 11 February 2016 (UTC)


 * If you want to search the technical/medical literature, it's probably good to know the name, which is "anorexia". You can use "-nervosa" to filter out that condition.


 * It seems "inappetence" actually is a word, at least according to Wiktionary, but I still think you are not likely to find much in English under that name. --Trovatore (talk) 00:23, 11 February 2016 (UTC)


 * Yes, it's in the OED with cites from 1691 to 1887.   D b f i r s   11:59, 11 February 2016 (UTC)


 * In the case of an intestinal infection, like the flu, the body can't always tell it from food poisoning, so avoiding any more (potentially bad) food until the condition clears is the wise course of action. StuRat (talk) 00:24, 11 February 2016 (UTC)


 * Please don't answer science quesions in terms of natural teleology. Wisdom is a function of conscious reasoning, not unconscious bodily reactions. --76.69.45.64 (talk) 19:51, 11 February 2016 (UTC)


 * I didn't think it was necessary to describe the full evolutionary process, but apparently it is: Those individuals who continued to eat food when they were in intestinal distress were more likely to ingest more of the bad food which gave them the trouble in the first place, and thus die, and therefore pass down fewer genes to offspring. In the case where the intestinal distress was unrelated to the food, the loss of a meal or two (for those whose genes caused them to lose their appetite) was not likely to cause death, so had little evolutionary cost.  The net result, then, would be evolutionary pressure to lose one's appetite when one had intestinal distress.  Note that there's no reason to expect this evolutionary pressure to be unique to humans, so this reaction may have developed long ago in our evolutionary past.  (Scavengers, on the other hand, being largely immune to food poisoning, may not react in the same way.)  StuRat (talk) 05:22, 12 February 2016 (UTC)


 * Without having any idea of the answer, given I focused in botany with my undergrad Bio major, the OP's question was well formed, and anorexia as a psychological condition has quite a different meaning from mere physiological inappetence due to a temporary infection. I find the above responses vary between irrelevance and rudeness. μηδείς (talk) 02:45, 11 February 2016 (UTC)
 * Anorexia nervosa is a psychological condition. Anorexia by itself is lack of appetite. --Trovatore (talk) 03:47, 11 February 2016 (UTC)
 * In fact, our article which was linked above by Scicurious over 3 hours before Medeis's reply (so I guess is one of the rude or irrelevant replies) [//en.wikipedia.org/w/index.php?title=Anorexia_%28symptom%29&oldid=703898072 includes] links to the International Statistical Classification of Diseases and Related Health Problems and Medical Subject Headings links (okay these are wikidata but I'm pretty sure they would have been there before any reply) on the symptom and several references (I think 4) which discuss anorexia of infection. Nil Einne (talk) 14:26, 11 February 2016 (UTC)


 * Purely as a thought experiment, perhaps your body has decided that the costs/dangers of bringing in new food and other possible issues, such as poisons and pathogens, outweigh the short and long term disadvantages of burning the body's reserves. And +1 to Medeis. Greglocock (talk) 02:58, 11 February 2016 (UTC)


 * The word "anorexia" literally means lacking appetite, but it's very commonly used as an abbreviation for anorexia nervosa, so its use this way could cause confusion. ←Baseball Bugs What's up, Doc? carrots→ 04:23, 11 February 2016 (UTC)
 * Nevertheless I believe it is the usual term in medicine, in English, for lack of appetite. However both words get plenty of hits on Google Scholar, so I can't be sure. --Trovatore (talk) 04:31, 11 February 2016 (UTC)
 * While I know counting search hits isn't generally useful when in the thousands, for me, 'anorexia -nervosa' on Google Scholar gets a few hundred k. 'inappetence' gets around 10k but many of these seem to be in animals. You need to include something like 'inappetence patient' or may be 'inappetence human' and that reduces results further. Doing something like 'inappetence -cat -dog -bovine -reindeer -sheep -cattle -porcine -cats -dogs -rabbit -horse -salmon -goat -rats -poultry -pigs -monkey' still seems to manage to find quite a few non human results. Even in animals, 'anorexia cat' seems to find a lot more results than 'inappetence cat' although not all results relate to anorexia in cats. Possibly dog is a better example since you avoid discussions of CAT scans and Cognitive analytic therapy, but I'm not a dog person. Nil Einne (talk) 16:26, 11 February 2016 (UTC)


 * Appetite is regulated by a number of factors including leptin, ghrelin, cholecystokinin, and neuropeptide Y. In acute illness, an number of inflammatory cytokines are released. Among these, interleukin-1 alpha (IL1A) which activates Tumor necrosis factor alpha (TNF alpha) are known to suppress appetite. Interleukin-18 is also known to suppress appetite. As there is a complex interplay of signal molecules, I do not want to make this sound like a complete answer. IBiologicalMe (talk) 13:26, 11 February 2016 (UTC)
 * I should also add that the references I found are the first one I could find, but are probably not the best ones. BiologicalMe (talk) 13:32, 11 February 2016 (UTC)

Thank you very much! the informaition about the factors is very interesting! 93.126.95.68 (talk) 18:37, 11 February 2016 (UTC)