Wikipedia:Reference desk/Archives/Science/2015 November 4

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November 4

high concentration of sugar and salt outside the cells

I would like to know and understand what happens when having high concentration of sugar or salt outside the cell. Should it constrict the cell or blow it? 78.111.186.95 (talk) 09:16, 4 November 2015 (UTC)

Please see the second paragraph of our article on Crenation. -- ToE 10:47, 4 November 2015 (UTC)

Plasmolysis. The rule is that the water goes where the solutes are, to even out the concentration (osmosis). Wnt (talk) 16:07, 4 November 2015 (UTC)

In plain English, it will draw water out of the cells. See also, how to murder slugs. μηδείς (talk) 22:25, 4 November 2015 (UTC)

Destruction of medicinal articles

In relation to vandalism on Wikipedia (please have look into https://en.wikipedia.org/w/index.php?title=Talk:Postural_orthostatic_tachycardia_syndrome&diff=689022628&oldid=689022484), my question is:

Why does the Wikipedia allow editors to destroy initially very good articles? --81.6.59.42 (talk) 13:32, 4 November 2015 (UTC)

Wikipedia enables users to do nearly everything to nearly every article. The hope is that this improves, on average, the quality of articles. It's not guaranteed to work (although the evidence so far is that it does), and it's certainly not a monotonic process. In order to make the process more efficient, Wikipedia has certain policies and guidelines about what users should and shouldn't do. Sometimes these rules lead to what looks like (or even may be) a decrease in quality - e.g. if a user removes parts of a well-written and maybe even correct article because of insufficient sourcing. We don't have a Truth-O-Meter, and we often have no way to distinguish between real experts and victims of the Dunning-Kruger effect. That is why we rely on external reliable sources per WP:RS. --Stephan Schulz (talk) 13:59, 4 November 2015 (UTC)

This is not a forum for debate or opinions
The following discussion has been closed. Please do not modify it.
All I can say to Stephan is "What planet are you from"? My experience with Wikipedia over many years has convinced me that there is rampant bullying, shallow intellectual arrogance and disregard for the so-called "rules" of fair play. Wikipedia has never stirred a finger to counter these negative influences and they have driven thousands of well-intentioned contributors away from the project. Any number of people have spent days creating an article only to have it eliminated by some Wikinazi who replaces the entire effort with the word "twaddle". If these bullies are well-entrenched up the food-chain, it is impossible to displace them. Wikipedia is indeed free-to-edit but the proposition that the edits are in the main constructive is misleading to the point of being risible. — Preceding unsigned comment added by Captainbeefart (talk • contribs) I'm afraid I'm going to have to agree with the above editor. 131.251.254.154 (talk) 14:29, 4 November 2015 (UTC) Odd. People who insist that Wikipedia doesn't treat them fairly are those who simultaneously insist that concepts like providing reliable sources to support what is written in an article shouldn't apply to them. Maybe if people kept their head down and simply dug through the medical journals and neutrally presented what they said, there wouldn't be these problems. Just a thought. --Jayron32 16:17, 4 November 2015 (UTC) There are a number of toxic tendencies brought to bear on an edit like this. First, there is a general hostility to primary sources, which of course is altogether at odds with how scientists look at research papers. Wikipedia policy doesn't ban primary sources, but has just enough skeptical language that some insist that it does, or act like it. Second, there is a very strong medical lobby, with actual funding from outside companies. There are groups like Wiki Med Inc that try to patrol articles for "bad" information - and indeed bad information exists, but as defined by who? The problem is that when people are looking to patrol for misinformation, they get the mindset that Wikipedia articles are written for patients, instead of written for researchers and students or whoever else is interested; and they therefore think that non-human model systems aren't interesting, ongoing research isn't interesting, etc. Last but not least, there's the concern that articles (or Reference Desks) shouldn't really be too useful for patients, because anyone with a serious question is supposed to $ee Their Doctor about it. It's all very sad. The medical industry used to have an awesome Jonas Salk kind of ethics, but now they're like bullies robbing kids of their lunch money, only in this case it's more like robbing them of all their money if they need a drug and they can find a way to do keep-away. Nobody can tell me doctors are on the up-and-up when we as a society intentionally leave hepatitis C rampant so it can make some people a buck. Wnt (talk) 16:21, 4 November 2015 (UTC) It should be pointed out that Wnt's opinion (that one should ignore the advice of people who are trained in how the human body works, and how to treat diseases of it, and instead just try random fixes from random, unvetted sources of information or advice from people with no proof of training or knowledge) is peculiar to say the least. The idea that one should seek advice or treatment from people with proper knowledge and training should be uncontroversial. Wnt seems to think that training would disqualify someone from being trusted. I have no idea what leaps of logic that requires. --Jayron32 17:54, 4 November 2015 (UTC) Please don't put words into other users mouths, especially if it clearly has nothing to do with what they were actually saying. Medical doctors know very little about how the body works, only to diagnose problems and how to treat them. Scientists know how the body works. It's the mechanic vs the engineer. His assessment about wiki articles is spot on. The ridiculous emphasis on patient information, combined with the active discouragement of primary sources (the single most important source of information), makes many biomedical articles on wiki pretty much useless. Fgf10 (talk) 22:18, 4 November 2015 (UTC) WP:Why MEDRS? is a good essay about why we avoid primary sources. In short, assessing the significance of primary research is a science in itself. There is no reason to risk allowing (presumed) amateurs to do the job when scientists have already done it for us in secondary sources. KateWishing (talk) 22:35, 4 November 2015 (UTC) Are you saying that mechanics don't know how automobiles work? If one didn't, he wouldn't be able to keep that job very long, I'm sure... --Jayron32 00:12, 5 November 2015 (UTC) You have a fairly peculiar belief about the extent of understanding of physiology in the average physician. It's true that only a certain subset are biomedical researchers who are actively expanding understanding of physiological mechanisms, but the statement that they "know very little about how the body works" is patently absurd; excepting academics in a handful of fields, no class of person has a better average understanding of physiology than a person with a medical doctorate. Your average would-be physician has taken scores of classes in anatomy, physiology, and biochemistry before they even arrive at medical school, to say nothing of what that training entails (though needless to say this is variable by nation). Anyway, your argument is a complete non-sequitur, since the overwhelming majority of MEDRS utilized in Wikipedia articles come from researchers publishing in peer-review journals, not from doctors practicing in a clinical environment while practicing physicians are more likely than most every other type of medical researcher to be providing a primary source in lieu of a secondary. Meaning no offense, but your wires seem a little crossed on the nature of sourcing for these particular articles. I happen to agree with Jayron that Wnt's comments are soapboxing at best and verging on potentially harmful conspiracy theory. I won't go into details of where I see these comments as indicative of strawman perspectives set up against a broadly necessary profession, because frankly, this is not really the place to be having that discussion per WP:NOTAFORUM. But I will say that Wikipedia's policies on precluding that information were engineered to protect people from a very real possibility of harm done by those who have exaggerated notions of their own expertise in certain fields and would indulge in these delusions without the least forethought as to the ultimate consequences. By extension, these rules also protect the project from liability and having its reputation undermined by those more commited to their delusions of grandeur than the well-being of the project. A look at the rampant speculation that regularly takes place on this particular desk, under the erroneous presumption that WP:V does not really apply here, ought to be enough to give anyone fair warning how much off-the-cuff diagnosis would take place here, were it allowed. In any event, for anyone who wants to discuss Wikipedias standards on content and sourcing in medical articles, there are a lot of better places to do it: WP:VP, WP:CD, Wikipedia Talk:MEDRS, and countless others. As this is essentially a policy question, this seems not to be the ideal space. Snow let's rap 06:00, 5 November 2015 (UTC)

The IP should provide some sort of reason as to why this "destroyed" the article. You are able to challenge edits if you want to, but there was no reason provided as to why this edit in particular was wrong or somehow unconstructive. Scarlettail (talk) 20:07, 4 November 2015 (UTC)

In fact the edit summary appears to be accurate. Most of the information which was removed appears to have been poorly sourced. Can the IP provide one example of information which was well sourced and removed? Nil Einne (talk) 16:26, 5 November 2015 (UTC)

Flashes preceding blasts in opencut pits

When footage of blasts in open-cut pits is viewed one sees linear flashes of light across the ground at extreme speed immediately prior to detonation. These must be related to fuses but what exactly is occurring? Why the light show?

If you mean when rows or arrays of explosive (dynamite or a successor) is used in quarrying, you're seeing the explosion blowing out through the drill holes (the holes into which the explosive was tamped). This is the detonation, not prior to it, but you see it before you hear it, because sound travels slower than light. -- Finlay McWalterᚠTalk 14:04, 4 November 2015 (UTC)

Naah, Finlay. The lights flash sideways. One sees them skip over ground where nothing explodes. — Preceding unsigned comment added by Captainbeefart (talk • contribs)

detcord. -- Finlay McWalterᚠTalk 14:38, 4 November 2015 (UTC)

(EC) WAG, but this might be the network of fuses which link all the explosive charges, these would be similar to the "black match" or quick fuse type mentioned there, used so that all the charges detonate simultaneously. [Edited to add: More accurately, what Finlay said.] {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:43, 4 November 2015 (UTC)

Blasting caps come to mind. If they are on the surface, you can see the flash, while the secondary explosives are underground, so you don't see the flash, but only the results of the explosion. Since moving all that ground takes some time, there is a slight delay after the flash. StuRat (talk) 23:10, 4 November 2015 (UTC)

Yes. When blasting a face or strata, one doesn’t want all the charges to go off at once. It goes outer face to inner. Each charge can be be fitted with an standard delay fuze calibrated in milliseconds. The detcord (linear flashes of light) quickly primes all fuzes. The length of each detcord can be varied to match the standard delay's to synchronize the whole blast. Thus, ensuring that the charges go off at the right time.--Aspro (talk) 00:56, 5 November 2015 (UTC)

Good point. Form cracks on the surface first, then detonate the lower charges, allowing the cracks to propagate downward. StuRat (talk) 02:08, 5 November 2015 (UTC)

Two questions about the vertebrae

I have two questions about the vertebrae:

1) Are the Accessory process and Mammillary process unique for the lumbar vertebrae or they appear in the rest of vertebrae (cervical, thoracic).?

2) Is there any place (I mean site, page) that presents the differences between the types of vertebrae?

78.111.186.15 (talk) 18:00, 4 November 2015 (UTC)

we have this article you should be able to find the answers to your homework there. 64.170.21.194 (talk) 01:46, 5 November 2015 (UTC)

First of all, it's not homework, but I take it as compliment. Second, there is no information about the questions - in this article that I already before I asked my questions. Moreover, You wouldn't find these two simple terms in the article. So, in the next time before you judge questioners, please think a little bit and check what you write. I'm here in order to study, not because I'm lazy. Thank you. 78.111.186.63 (talk) 11:29, 5 November 2015 (UTC)

The information is not in the human vertebral column article, but it is in the vertebrae article, in Vertebrae#Variation. Looie496 (talk) 13:23, 5 November 2015 (UTC)

hiv transmission

If hiv is so easily transmitted through needles and anal sex, why isn't it just as easily transmitted through wounds of different people touching each other or through a bodily fluid (whether saliva, semen, vaginal fluid etc) touching a wound? 2A02:C7D:B8FF:7E00:25F3:6D6E:4020:6AA9 (talk) 23:15, 4 November 2015 (UTC)

I'm not sure that's correct. Are you sure that HIV isn't transmitted through wound contact with the same (or greater) chances of infection than through sexual contact? HIV does not have a section on transmission, but it says "Sexual intercourse is the major mode of HIV transmission." I think that means that is the major way it is actually transmitted in the real world. Far more people have sex than rub open wounds against each other. So just because more transmission happens via sex than via wounds does not mean that the virus cannot infect well through that vector. HIV can definitely be transmitted via blood. This [1] journal article says in the abstract

“ We know several facts about HIV transmission in the health care setting. First, blood is the single most important source of HIV infection. Second, exposure to blood through the percutaneous route is significantly more likely to transmit HIV than is mucous membrane or cutaneous contact. ”

I see no reason to believe that mingling of blood does not have the same, if not higher, risk of infection than sexual contact. SemanticMantis (talk) 23:42, 4 November 2015 (UTC)

One factor is that HIV is killed by contact with oxygen in the air. So, transmission is more successful where air is absent (inside a syringe) or limited (inside a vagina or rectum). StuRat (talk) 23:50, 4 November 2015 (UTC)

Do you have any citations for any of your statements here, Stu, so that readers may learn more about what kills HIV? --Jayron32 00:10, 5 November 2015 (UTC)

Sure, since you're apparently incapable of Googling it yourself: [2] (7 and 8 are relevant here). (Meanwhile, I'm still waiting on a ref for your baseless assertion here: Wikipedia:Reference_desk/Humanities#Bookshops_with_sofas_and_comfy_chairs). StuRat (talk) 00:33, 5 November 2015 (UTC)

1) That's a reliable site? Do you have anything that resembles something with editorial control or peer review? 2) You don't get to avoid providing any references ever because I made a side comment to a discussion once. The fact that someone who isn't you, once, didn't provide a reference to something, once, doesn't mean you never have to verify anything you ever say ever. That's not how life works. --Jayron32 02:33, 5 November 2015 (UTC)

The sponsor of that website also claims that he was "healed" from AIDS, cancer, a "dying kidney," and vertigo (sic) - "by faith alone." It is absolutely not a reliable website for scientific information on HIV or anything else. Nimur (talk) 08:45, 5 November 2015 (UTC)

Here's the HIV help line with the same info: [3]. Also, your "side comment" wasn't just unreferenced, it was unreferencable, because it was completely wrong and should have been immediately redacted. StuRat (talk) 03:01, 5 November 2015 (UTC)

Following up on this resource, the statement was provided by a volunteer who was not a doctor or a scientist. Their disclaimer states clearly: "Volunteers are not doctors, nurses, or other licensed professionals. Volunteers do not give advice, and strive to provide service-users with adequate information and appropriate referrals." The information on their website is not encyclopedic; it's essentially a free service intended to refer people to community resources, not to provide authoritative medical and scientific opinions.

I think the benefit of the doubt has been exhausted here; the assertion that air "kills" or "inactivates" the HIV virus is frequently repeated and rarely backed up with evidence. You need to find better sources, like peer reviewed medical journals; or you should rescind your claim. If there is actual scientific debate over this factual detail, it should be straightforward to find a review article that summarizes the evidence and arguments on both sides. Nimur (talk) 08:55, 5 November 2015 (UTC)

StuRat is wrong: [4]. Air does not sterilize stuff against HIV. However, the virus still needs a vector to enter the body, so syringes are more contagious that doorknobs. --Scicurious (talk) 03:03, 5 November 2015 (UTC)

Interesting. How did you find that ? I did Google searches on "air kills HIV" and "oxygen kills HIV" and didn't find it. (Note that your source does show that exposure to air kills HIV, just much more slowly than my sources said, over many days or weeks.) StuRat (talk) 03:09, 5 November 2015 (UTC)

Well, exposure to air kills you, just even more slowly, over many decades. --Jayron32 03:19, 5 November 2015 (UTC)

Also relevant for the discussion here, and also relevant because you keep not reading this exact statement, even though it's been told to you multiple times: Providing references has nothing to do with proving anything. You are not being asked to provide references because anyone thinks you're wrong, and requests to provide references are not accusations that you are wrong. No matter how many times you think requests to provide references are accusations of anything, they aren't. Your job is to provide references. Period. --Jayron32 03:29, 5 November 2015 (UTC)

Then why don't you always provide refs, even when asked ? StuRat (talk) 03:52, 5 November 2015 (UTC)

1) Yes, there are times when I haven't provided a reference. 2) That is irrelevant to the discussion at hand. You don't get to say "Look, I found this one time once, where another regular user forgot to provide a reference! It means I can continue to just repeat stuff I think I remember, and never provide a reference ever again". That isn't how life works. Finding cases where another person has violated expected norms once doesn't mean the norms never exist for you. Just start providing references for your answers. Like, as a regular habit. No one will ever bother you again about it. All you need to do is research reliable sources, or find a Wikipedia article which itself has reliable sources, and link them in all of your answers. The first time you do that, and then keep doing it, is the last time we have to repeat this same conversation. --Jayron32 04:05, 5 November 2015 (UTC)

"Let he who is without sin cast the first stone". StuRat (talk) 04:14, 5 November 2015 (UTC)

You do realize that that is "Let him (who be without sin) cast the first stone"? "Let he cast the first stone" whould even get you laughed of Wheel of Fortune". (WoF being one of the two TV shows I still watch.) μηδείς (talk) 05:37, 5 November 2015 (UTC)

I've never cast a stone. You're not being punished. You're being asked to follow expected norms. If you don't realize the difference between punishment and being told to do the right thing, I'm not sure you have the mental capacity to handle finding references for users here anyways. --Jayron32 14:32, 5 November 2015 (UTC)

I paraphrased. Is One Foot in the Grave the other show ? StuRat (talk)

I meant "watch live". Everything else I stream off the internet. I did recently download and watch all the One Foot in the Grave episodes though, so I am glad you are paying attention, and suggest you also see Waiting For God if you haven't seen it. μηδείς (talk) 23:03, 5 November 2015 (UTC)

From the Stanford Encyclopedia of Philosophy, here is the article on Search Engine Bias. When you "search" for something, a modern web-search engine finds it, even it if is not correct. Furthermore, if it is profitable to show you a result, the search engine will "find" it with high probability, even if it is not correct.

Can you see how this might be problematic if you search for "air kills HIV", or platypuses are reptiles.... or time is a cube? If anyone has ever published these incorrect statements on the internet, a modern web search engine will turn up a "positive hit."

Search engine results are not reliable sources, and they have no place on our encyclopedia. If you do not already know how to find and use a reliable encyclopedic source - and to distinguish reliable from unreliable sources - you should not be contributing to this encyclopedia. If you are using a search-engine to help prompt your recollection of a reliable source - or to narrow down a set of websites, then read and understand those websites, that is fine... but if you're just posting the first link that "matches" what you want, you really need to re-think your model of information consumption and regurgitation, and how that relates to Wikipedia's standards for content.

Nimur (talk) 03:19, 5 November 2015 (UTC)

Well, yes, Nimur. But who wouldn't sue his highschool if they let him graduate thinking a platypus were a reptile? WP:Competence is required, and ignorance wins big rewards. μηδείς (talk) 05:32, 5 November 2015 (UTC)

@Nimur and Medeis: You people and the arguing! But you ought to know better. Whenever a statement of biology is universally held to be the very height of vulgar idiocy, it is either true or is deemed "false" entirely arbitrarily. If you look up Reptile you'll see that the definition was redrawn in 2004 to clearly exclude the platypus. Before then, there was discord about whether mammals and birds should arbitrarily be excluded from amniotes to generate a paraphyletic clade of "reptiles", and one could just as easily decide to exclude all the placentals and call a platypus a reptile! Wnt (talk) 22:46, 5 November 2015 (UTC)

Actually, I was using reptile to refer to the evolutionary grade, not a clade. μηδείς (talk) 01:08, 6 November 2015 (UTC)

Participants in "blood brotherhood" may indeed end up with some genes in common - HIV genes, that is. [5] HIV is an enveloped virus and so far as I know all such viruses are vulnerable to air exposure one way or another (the latter article mentions desiccation as a reason; I think lipid peroxidation has a role also). While these things limit the spread of HIV none of them come with a money back guarantee - the specific conditions are important. Wnt (talk) 03:19, 5 November 2015 (UTC)

• [ec] Okay, if I may interrupt, first of all, HIV is readily killed by exposure to oxygen, so a wound-to-wound exposure would be an unlikely route, given people rarely hold actually open bleeding wounds together. That being said, there was a study popularized in the last few months that advised that if one could control STD's that cause open sores in Africa, one could drastically reduce the HIV transmission rate, the point being that sores on the penis or vagina exposed to the body fluids of an infected partner are ideal points of transmission.

Now, the confession: I have spent the last 15 minutes googling that and can't find the original source, which I am sure I must have found at Real Clear Science. This may have been in conjunction with an initiative from the B&M Gates Foundation. But I will keep looking. μηδείς (talk) 03:21, 5 November 2015 (UTC)

• • A little more to it. HIV has been transmitted from infected dentists to their patients [6] which is problematic considering its casual contact with open air wounds. Also, transmission rates for sexual contact are asymmetric and also varies by type of contact. With straight vaginal sex, an uninfected woman is much more likely to be infected by an HIV positive man than an uninfected man being infected by an HIV positive woman. It's pretty rare for women (even infected women) to transmit the virus to men during vaginal intercourse. Anal sex is not as gender selective but the risk is higher for the uninfected person being penetrated. This is why the gay community has higher incidents and also why women are more likely to be transmission victims from a polyamorous man than a man being infected through the conduct of a polyamorous woman. --DHeyward (talk) 11:46, 5 November 2015 (UTC).

Well ok, yes, the chances of someone holding open wounds together is rare but let's look at a more likely scenario. Oral sex with an open wound in the mouth or on the lips. That must happen alot but you don't really hear of hiv being transmitted this way. Why not? 2A02:C7D:B8FF:7E00:25F3:6D6E:4020:6AA9 (talk) 07:40, 5 November 2015 (UTC)

Physics. For women to be infected, there must be some penetration and an exchange of infected fluids. The vaginal wall is susceptible (much more so than through the skin of the penis). The main sexual transmission routes are through ejaculate from an infected male. I believe the main spread of infection where women are the carrier is to their children. They can transmit it sexually but that number is dwarfed by men transmitting it through sex. --DHeyward (talk) 11:46, 5 November 2015 (UTC)

@2A02:C7D:B8FF:7E00:25F3:6D6E:4020:6AA9: [7] has a thorough discussion about ways of infection, and the difficulty of quantifying the rate of infection, among other research pitfalls. In summary: deep cuts or infected injuries are more dangerous than just an injure. And it's difficult to isolate cases of oral sex that exclude other forms of intercourse. It's still plausible to get infected, it's just a (much) lower risk. --Scicurious (talk) 15:38, 5 November 2015 (UTC)

This [8] while coming from a source for people living with HIV/AIDS says similar so perhaps not unbiased, says similar and also discusses penetrative (although most of what you mentioned would apply to both anyway). I think another key point although not really mentioned in either source, is that while the risk of HIV appears to be quite low, the risk of some other STIs is high enough that few health authorities are going to suggest protection isn't neessary. Nil Einne (talk) 16:19, 5 November 2015 (UTC)

what about for men then Dheyward? 2A02:C7D:B8FF:7E00:A866:8A26:EDC8:346D (talk) 18:54, 5 November 2015 (UTC)

It was stated that HIV is killed by exposure to air, but there is concern that it might persist long enough on the surface of a glucometer to be spread between patients. See a CDC guide on use of blood sugar monitoring equipment. Even when a fresh lancet is used for each person,somehow contamination of a shared meter can spread blood-borne pathogens such as Hepatitis B, hepatitis C virus, and HIV, Typical meters are not made to be sterilized. The FDA says"For blood glucose meters, the primary viruses of concern for bloodborne pathogen transmission between multiple patients are human Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), and Hepatitis C Virus (HCV). However, due to its robust nature, HBV is the most common virus in the observed outbreaks to date" and that if a meter is to be used for more than one person, it must be certified as being capable of being sterilized. The FDA also says "70% ethanol solutions are not effective against viral bloodborne pathogens and the use of 10% bleach solutions may lead to physical degradation of your device." The meter is not actually ever in contact with the patient in normal use; just a test strip and a single use lancet. Somehow there is transfer, and there have been numerous cases of hepatitis transmission among patients in nursing homes via testing equipment. Edison (talk) 14:33, 6 November 2015 (UTC)