Science desk
< August 11	<< Jul \| August \| Sep >>	August 13 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

August 12

Interesting Bacterial or Viral Infection.

What is an interesting Bacteria or Virus that affects humans? Please answer quickly.

JoshMuirWikipedia (talk) 06:53, 12 August 2016 (UTC)[reply]

"Interesting"? To whom? If this is a topic for an essay, try Y. pestis (bubonic plague), V. cholerae (cholera), or V. major (smallpox) for some diseases with major social consequences. Tevildo (talk) 07:22, 12 August 2016 (UTC)[reply]

Yes Tevildo, it is just something I have to study for an essay that I have to present on and hold a 10th grade classes attention with. JoshMuirWikipedia (talk) 07:25, 12 August 2016 (UTC)[reply]

It also has to be something no-one else will be doing so preferably not too generic. JoshMuirWikipedia (talk) 07:27, 12 August 2016 (UTC)[reply]

There's Saint Vitus Dance (caused by a type of Streptococcus), which causes involuntary movements like Tourettes and was blamed for some of the dancing mania of the middle ages. That's interesting enough to hold school-kids attention (I remember it got a lot of attention in the Horrible Science/Horrible Histories books). Smurrayinchester 07:39, 12 August 2016 (UTC)[reply]

You might also want to consider S. marcescens. See Transubstantiation for why it's interesting. Tevildo (talk) 07:42, 12 August 2016 (UTC)[reply]

Wikipedia has a Categories like Category:Bacterial diseases. --Hans Haase (有问题吗) 09:39, 12 August 2016 (UTC)[reply]

Thank-you all very much for your answers, by coincidence this question was my 1000th edit! JoshMuirWikipedia (talk) 11:15, 12 August 2016 (UTC)[reply]

If you're still looking for an idea, I'd suggest Enterovirus D68, which caused an outbreak of acute flaccid myelitis (problems similar to polio, but with much lower likelihood per infection). There was a large outbreak in the U.S. in 2014. I haven't seen news about it lately ... HOPEFULLY that means it actually didn't have further outbreaks, but there's something extra for you to look up if you want. Wnt (talk) 13:33, 13 August 2016 (UTC)[reply]

Minions

(inspired by the previous question) What species of Bacilli are these supposed to be (if any)? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 07:35, 12 August 2016 (UTC)[reply]

Tardigrade imaged with a scanning electron microscope

Creator Pierre Coffin said, in a 2015 interview, that minions "cannot reproduce or divide themselves..." In other interviews, the creator explains that they have always existed and do not reproduce, because this explanation is less awkward than any alternative.

These statements, which are clearly and indisputably canonical, seem to preclude any classification of minions as any type of bacteria, despite superficial similarities to, say, some kind of lovable giant microbe.

Speaking from personal experience, I have seen a Minion form by inflation, so perhaps these creatures are not as well-understood as we think.

Nimur (talk) 11:58, 12 August 2016 (UTC)[reply]

Visually, I'd go with tardigrades. Color them orange and they are kind of close. StuRat (talk) 02:15, 13 August 2016 (UTC)[reply]

Shrinking PET bottle phenomenon

I'm currently dealing with a self-accumulation of a few hundred PET bottles, mostly though not entirely the standard 2-litre version. These have been entirely emptied of their carbonated drink content, the tops firmly screwed back on, and left indoors and out of direct sunlight for anything up to 5 years (all this by myself, so the circumstances are not in doubt). To eliminate one possible idea, they have not at any time been exposed to hot water.

I have noticed that, although firmly sealed, such bottles shrink laterally due to decreased pressure within them, progressively with age. Typically they become concave on three sides, to the extent that they may (in the oldest cases) lose more than half their volume, and the inner curves of the three concave sides almost touch. When re-opened, air is sucked in, demonstrating the reduced pressure within, although those most distorted (and for longest, as the effect is progressive) may not return entirely to their original fully-round profile.

Can anyone reference or suggest the ultimate cause of this? I have already concluded that the caps cannot form any sort of one-way valve and be reacting to temperature changes (which would only be within the range of 9–25 Celsius), and that any drops of the original content that may be left in some of the bottles are too negligable to have any effect. I'm aware that the material is slightly gas permeable, but cannot see why this would operate in an osmotic manner when the atmosphere outside and inside the bottles is essentially the same. I'm also aware that the material is subject to some shrinkage during manufacture (which accounts for most ghits on the topic), and very minor shrinkage thereafter, but this would not account for either the scale of the shrinkage, its confinement to lateral dimensions (the bottles do not get shorter at all), and the reduced internal pressure which seems to be the proximate cause of the shrinkage. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 12:45, 12 August 2016 (UTC)[reply]

Do you rinse them before resealing? Are they being stored in something different from "normal" room temperature? Also, do you have a recycling center in your area? ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:13, 12 August 2016 (UTC)[reply]

Answers in order: no; no; yes, to which I'm now taking them in tranches. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 20:51, 12 August 2016 (UTC)[reply]

My suggestion (original research, though maybe someone can look) is that the plastic itself is starting to break down and softening. shoy (reactions) 15:00, 12 August 2016 (UTC)[reply]

Aside from the loss of internal pressure and apparently consequent shrinkage, the plastic seems unchanged. {The poster formerly known as 87,81.230.195} 2.123.26.60 (talk) 20:51, 12 August 2016 (UTC)[reply]

If the bottles are not homogeneous, such as having a crystal structure or chemical concentration on the inside than on the outside, that could produce deformation such as you suggest. An article about their manufacturing says that impurities form in the PET bottles as they are blow into a mold by hot air and then quickly cooled. There might be differences in impurity concentration or in crystallization between the inside and outside resulting in shrinkage of the outside. Pop bottles are demonstrably not at all gas tight, since this week I threw out two pop bottles which had a 2015 expiration date, and which were flat when opened, due to the carbon dioxide dissolved in the liquid escaping from the bottle. If the outside shrank for some reason more than the inside, it might produce the effect seen, since the air inside would be able to escape over time.Edison (talk) 15:29, 12 August 2016 (UTC)[reply]

I don't see how this would produce a markedly lower pressure inside the shrunken bottles. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 20:51, 12 August 2016 (UTC)[reply]

Likely they're simply leaking more air through the seal and/or plastic itself than "sucking" it back in due to temperature changes.--TMCk (talk) 15:44, 12 August 2016 (UTC)[reply]

Yes, that was my first guess. It seems likely that such a bottle is more resistant to expansion than contraction. A temporary period of low atmospheric pressure would cause the higher pressure in the bottle to force some enclosed air out through the imperfect seal at the cap. Then when the atmospheric pressure increases, the bottle would simple contract rather than have air forced back into it. CodeTalker (talk) 18:15, 12 August 2016 (UTC)[reply]

But once it's shrunken, unsealing a bottle's top results in more air going in, and the bottle re-expanding, so there is no resistance to expansion other than the lower internal pressure. In any case, either the pressure or temperature variations would need to be far higher than are occurring inside a house in a temperate climate (Southern England) to account for such extreme (up to 50%) reductions in volume. Also, the shrunken bottles are never seen to noticeably increase in volume again with temperature or barometric pressure changes. {The poster formerly known as 87,81.230.195} 2.123.26.60 (talk) 20:51, 12 August 2016 (UTC)[reply]

Keep in mind that the positive pressure decreases over time with loss of air volume while the negative pressure will be unaffected.--TMCk (talk) 19:12, 12 August 2016 (UTC)[reply]

Of course this assumes clean bottles in which nothing is left that would use up gases e.g. oxygen.--TMCk (talk) 19:38, 12 August 2016 (UTC)[reply]

As mentioned originally, the bottles are emptied of all but traces of the original carbonated beverage contents (because I drink it all) and then firmly resealed. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 20:51, 12 August 2016 (UTC)[reply]

Do you have a sense of how long it takes for a given bottle to start malforming? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:59, 12 August 2016 (UTC)[reply]

I haven't been actively monitoring them (although I might start doing so now), but I would estimate something in the region of 4–8 months. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 16:15, 13 August 2016 (UTC)[reply]

Keep a few of the shrunkest. You may have discovered a new form of plastic-eating, gas metabolizing bacteria!? Sagittarian Milky Way (talk) 22:49, 12 August 2016 (UTC)[reply]

From US Patent 4260567: It is well known that plastic material has tendency to creep or shrink when heated and this is especially true of oriented plastic containers such as [PET] bottles....Our findings have shown that on the average our bottle has a volume of 1930 cc. and at temperatures of 140° F. (relative humidity 10%) for four hours displays a shrinkage of 65 cc. AllBestFaith (talk) 01:35, 13 August 2016 (UTC)[reply]

Interesting insofar as the temperatures of these empty bottles have at no time risen past 25°C (77°F) or dropped below 9°C (48°F) (I have a Max-Min thermometer in the house), while the shrinkage has been up to 1000cc (from a nominal 2000cc) so far (over ca. 5 years). {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 16:15, 13 August 2016 (UTC)[reply]

First of all, I'm speculating here. I think that the gas inside the bottle, after drinking the carbonated contents, is significantly enriched in CO₂. More than 50% CO₂ I mean. The plastic of the bottle is slightly permeable to gas, so as long as the partial pressure of the CO₂ in the bottle is ~~lower~~ higher than in the outside atmosphere, the gas will leak out, just as oxygen and nitrogen will leak in. Assuming the plastic is more permeable to CO₂ than to oxygen and nitrogen, the pressure in the bottle will drop. It's basically osmosis, but with gas mixtures instead of aqueous solutions. PiusImpavidus (talk) 09:38, 13 August 2016 (UTC)[reply]

I assume you mean higher than in the outside atmosphere, because I'm fairly sure I'm not living in an atmosphere >50% CO₂!

This seems to me the most plausible suggestion so far. I might try setting up some comparison pairs of bottles, one sealed immediately after being emptied of beverage and the other thoroughly flushed with air. As mentioned above, however, it will likely take months to years before any differential effects become evident. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 16:15, 13 August 2016 (UTC)[reply]

I suspect there is a one-way valve phenomena at work. The cap may allow gasses to escape through the threading of the cap but the same threading in the cap may resist the returning of gasses to the bottle when outside atmospheric pressure increases. The construction of "threaded parts, such as screw-on bottle caps" may not be symmetrical as one may assume. One reason for such asymmetry may involve manufacturing processes, but I think other reasons can be imagined. I cannot think of a mechanism by which asymmetrical construction of threading involving cap and bottle would result in a "one-way valve effect" that favors the movement of gasses in one direction, but that is where my suspicions are found. Bus stop (talk) 18:25, 13 August 2016 (UTC)[reply]

An experiment would be to seal the caps to the bottle in a way deemed "air tight", perhaps using heat, glue, silicone sealant or some other sealant. This would either rule out the implication of the caps or point to the need for further research into the cap design. Bus stop (talk) 18:30, 13 August 2016 (UTC)[reply]

The movement of air in one direction may be favored by the displacement of the cap away from its container by atmospheric circumstances in which there is greater pressure within the container than in the surrounding environment. Movement of air in the other direction may be disfavored by the displacement of the cap towards its container by atmospheric circumstances in which there is lower pressure within the container than in the surrounding environment. Though the cap may be firmly in place there could nevertheless be the possibility of movement of the cap (which I have been calling "displacement") given sufficient pressure differentials. This movement of air may not be equally favored in both directions because displacement of the cap towards its container may result in a tighter seal. Bus stop (talk) 13:44, 14 August 2016 (UTC)[reply]

I'm fairly sure that the caps (which habitually I screw on quite tightly) form complete seals in both directions, particularly at the relatively low pressure differentials involved in empty bottles. They certainly don't allow any significant gas passage when the bottles are full (of carbonated beverage), because the excess pressure in an unopened full bottle is quite considerable, and such bottles must stay pressurised for significant periods (up to several weeks?) between filling and eventual sale. {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 14:28, 15 August 2016 (UTC)[reply]

You make a good point that the liquid and gaseous content of the bottle is considerable when new. A difference is that one is both liquid and gaseous (unopened) and the other is largely gaseous (opened). Viscosity, surface tension, perhaps other factors that I may not be aware of, may inhibit movement of the liquid molecules but may allow more free movement of the gaseous molecules. This is just speculation on my part. It may be that a silicone sealant in the juncture between the cap and the bottle may prevent movement of air and thus prevent the collapse of the bottles that you are observing. This would implicate the juncture between bottle and cap as somehow involved in the observed phenomenon. Bus stop (talk) 15:50, 15 August 2016 (UTC)[reply]

It may be that a degree of tightness is what creates the one-way valve that I am postulating. We want to rule that out by unquestionably creating an air-tight seal. Bus stop (talk) 16:14, 15 August 2016 (UTC)[reply]

Electricity and fish

I'd like to know why if I threw a toaster into the sea, why aren't all the fish in the sea electrocuted, as would happen if I had a toaster in my bath. Is it possible to electrocute hundreds of fish, and just scoop them up when they float to the surface? -- 2A02:C7F:7E06:3000:B4F5:8546:402C:23ED (talk) 16:29, 12 August 2016 (UTC)[reply]

Your tub is a small, confined space. In the ocean, or any large body of water, the toaster's circuitry would burn out before it had a chance to affect anything that wasn't right close to it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:34, 12 August 2016 (UTC)[reply]

Electrofishing may be of interest. Richerman (talk) 18:48, 12 August 2016 (UTC)[reply]

I don't believe a toaster (or hairdrier) thrown on a bath tube will kill everything in it. I expect the fuse to blow if that happen. Of course, in movies it's much cooler seeing someone fry in his bath tube than having a blown fuse. --Hofhof (talk) 21:07, 12 August 2016 (UTC)[reply]

Assuming you mean the fuse has been bypassed, the shock would quickly dissipate as the surface area of an ever-widening hemisphere of water increases. I think it would vary inversely with the square of the distance. So, the shock amount would be 1/100th as great at 10 meters as at 1 meter, or 1/10000th as strong at 100 meters as 1 meter. This means the shock would become nonlethal at a fairly small distance, although it may remain detectable for quite some distance, especially by fish that have electrical sensors (used to detect, prey, etc.).

This assumes the electricity dissipates evenly in all directions. If you had a cathode and an anode, then the field would be stronger between the two than in random directions at the same distance. StuRat (talk) 22:59, 12 August 2016 (UTC)[reply]

That's exactly how electrofishing works. Richerman (talk) 09:00, 13 August 2016 (UTC)[reply]

Electrical resistance and conductance.--TMCk (talk) 23:27, 12 August 2016 (UTC)[reply]

Also Electric eel. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 02:45, 13 August 2016 (UTC)[reply]

I have the unfounded suspicion that most of the bathtub electrocutions occur where someone well grounded in the bath reaches out with a hand, passing the current directly through the heart on its way to the bathtub. I imagine sometimes the offending item is dragged into the bathtub after the shock begins. I would bet that a toaster thrown in a bathtub might not actually kill the person targeted because it would have many paths through tapwater or through less critical parts of the body that would compete against a lethal path - though depending on the circuit breaker used, the total current flow might be very much greater than if you simply stuck a knife into an outlet. The skin resistance of a dry human is actually much higher than that of typical tapwater, especially when impurities have been added, but the internal resistance of human flesh is actually very low, and if thoroughly wet I don't know if that barrier still exists, so this is NOT a guarantee, especially if your water is particularly low in ions. Suffice it to say that without seeing the direct experiment, I think it should not be assumed that what they show in the movies is real. Wnt (talk) 13:49, 13 August 2016 (UTC)[reply]

And now that I've tried my best philosophy, let's see what I can find in data: to start with, there's an interesting phenomenon of a pale stripe on corpses (mostly suicides) at the level of the bathtub [1] which can be postmortem, but might be weaker then. So there's some kind of surface conduction effect I'd never have guessed at which just blows all our inverse-square stuff right out of the water. These guys talking about electrons "making a beeline for the ground" likewise stand exposed. And this article describes a tragic case where TWO girls were killed when a hairdryer fell into a bathtub, which argues very strongly against a "lucky path through the heart" explanation. Lee Harvey Oswald would have been hard pressed to drill through two hearts in a shot. The article also says that fatalities from dropped hairdryers averaged 18 a year. But... the one thing these statistics leave out is how many times somebody did the same unsafe thing and emerged shaken but uninjured, so my skepticism is not totally defeated, but it definitely will maintain a more respectful distance in the future. Wnt (talk) 14:00, 13 August 2016 (UTC)[reply]

Prolonged exposure to an electrical current can kill, even though that current is at a much lower level than would kill instantly. The case of the two girls in the bathtub is an example. For instant death to occur, it would either have to burn tissue or possibly cause the heart to fibrillate, although I suspect that in the later case most people's hearts are able to "reset" on their own (we only hear about fibrillation being a problem in the small portion of cases where this reset doesn't work). However, even at low levels the nerves' actions are interrupted temporarily, and if this "temporary" is long enough to keep the heart from beating until brain death occurs (maybe 10 minutes at normal temps), then death will occur. I myself, as a kid, put my hands on a fence I didn't know was electrified, and my fists compressed around it. Had it not been the type that pulsed on and off, I wouldn't have been able to let go and might have eventually died. (I don't know if my heart was beating during the shock.) StuRat (talk) 15:10, 13 August 2016 (UTC)[reply]

Ocular bruising from tooth extraction

This image, File:Black Eye 01.jpg, depicts "Black eye after extraction of a wisdom tooth". Assuming that the subject wasn't punched in the face during the extraction process, how would the extraction of a wisdom tooth produce a black eye? Even the upper wisdom teeth are much farther from the eyes than they are from other regions, e.g. the nose, and of course they're a decent distance from any spot on the skin; I don't understand how a significant quantity of blood could migrate all the way to the eye-area skin in this manner. Nyttend (talk) 20:19, 12 August 2016 (UTC)[reply]

The upper jaw wisdom teeth are not far from the eye, maybe it's 3-4 cm.

Wisdom tooth extractions is a much bigger damage than a punch. And a punch to the chin could also cause a black eye.

Blood migrates under the skin, under the eye it's visible.

A patient could have taken an aspirin (= blood thinner) after the operation. --Hofhof (talk) 21:01, 12 August 2016 (UTC)[reply]

I have seen the same blackness below the eyes after cranial surgery and wondered about the cause. To be punched in the eye at the dentist would be unfortunate. To be punched in both eyes sounds more like carelessness. AllBestFaith (talk) 01:10, 13 August 2016 (UTC)[reply]

The posterior superior alveolar artery and other blood vessels in this diagram connect to both the "tooth area" and the "eye socket area,” and in some cases, can be the source of blood that pools near the eye, causing the cosmetic discoloration

Here is Retrobulbar Hematoma After Third Molar Extraction: Case Report and Review (2010, Journal of Oral and Maxillofacial Surgery). As the title promises, it provides an incredibly detailed case-study and review of this condition (a severe complication of a "black eye" that occurs after a wisdom tooth extraction operation). If you like fancy latin-sounding names for stuff, this is the paper for you... for example periorbital hematoma just means blood pooling in the soft tissues around the eyes, or, "a black eye"; while a "retrobulbar" hematoma is a much more severe case of blood pooling behind the eye). The paper describes the plausible mechanisms that can cause these conditions, and the authors put forward their opinion on the probable cause in one instance: "uncontrolled bleeding from branches of the posterior superior alveolar artery after upper third molar removal may track up through the pterygomaxillary fissure into the pterygopalatine fossa and eventually drain into the retro-orbital space via the inferior orbital fissure."

That's a lot of Latin-esque anatomy terms, but in plain English, this means that blood flowed from the "tooth area" through the "face area" toward the "eye area." In some cases, this is not a problem, and in some cases, it can be a "medical emergency."

The paper I linked above cites some several dozen other papers on the topic, including both periorbital- and retrobulbar- cases ("regular" black eyes and more serious variants), including cases caused by all sorts of other procedures (not just tooth extraction - these conditions can occur in lots of other circumstances!) If you really want to follow up with even more diagrams and medical photographs, that's a starting place. Here's one more: Subconjunctival ecchymosis after extraction of maxillary molar teeth: a case report (Dental Traumatology, 2010), which describes the black eyes without the retroorbital hemmorhage complication.

Nimur (talk) 03:15, 13 August 2016 (UTC)[reply]

Drug names

Chlorpromazine is one of the better-known typical antipsychotics, sold under many names, one of which is Largactil (which redirects to the chlorpromazine article). Promazine is a rather more obscure drug in the same family. As far as I can tell, "Largactyl" is not the name of a drug - the main hits are for an album track by Amebix, and an arts event in Southwark organized by CoolTan Arts (no article, but see Artangel). I suspect that these names are an understandable misspelling of Largactil. However, Largactyl redirects to the promazine article, with no hatnote or mention on the page. Is Largactyl actually a brand of promazine? If so, we should keep the redirect as it is, add a hatnote, and source the name. If, as I suspect, it isn't, we should change the redirect. But I'm not able to determine what the true situation is - I'm sure the Reference Desk is capable of this research. Tevildo (talk) 21:41, 12 August 2016 (UTC)[reply]

Largactil® is a trademark for chlorpromazine hydrochloride first registered in 1953, renewed in 1954 but now expired (according to US Patent Office). This might be confirmed by the Marketing Authorisation Holder for Largactil in the UK which is: Sanofi, One Onslow Street, Guildford, Surrey, GU1 4YS, UK. Tel: 0845 372 7101. I confirm that Largactyl does not show up in a trademark search, only as the name of a heavy metal ~~noise~~ musical composition, and there's nothing to indicate a connection to Promazine. Tevildo is correct. AllBestFaith (talk) 01:02, 13 August 2016 (UTC)[reply]

Thanks for the information! Is Amebix the best target for the redirect? It's the only reference in the encyclopaedia to anything actually called "Largactyl". Or would it be better to redirect to Chlorpromazine as a likely misspelling? Tevildo (talk) 08:49, 13 August 2016 (UTC)[reply]

Trademark registration authorities apply distinctiveness criteria as a condition to approve trademarks. To suggest "helpfully" to a user that they really mean a differently spelled prescription medicine can have consequences similar to giving the medical advice that Wikipedia is unqualified to do. The drug chlorpromazine concerned can have serious adverse effects including death if wrongly administered. The foregoing are reasons not to redirect Largactyl to Chlorpromazine. AllBestFaith (talk) 17:39, 13 August 2016 (UTC)[reply]

I agree. I've changed the redirect to point to the band's article, and added an appropriate hatnote. Tevildo (talk) 18:34, 13 August 2016 (UTC)[reply]

Wikipedia:Reference desk/Archives/Science/2016 August 12

Contents