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August 18

Good Calculus-Based Physics Book

Can someone please recommend a good introductory physics textbook that explains the concepts using calculus, rather than algebra? I have one of the standard intro textbooks, and I'm having trouble bridging the gap from the simplified explanations it provides to the more mathematically rigorous ones that I find elsewhere. For example, the Wikipedia page on work defines it in terms of a line integral: I know how to work with those, but the examples from my calculus textbook are too abstract for me to know how to apply them to real-world problems (e.g. they use generic polynomial functions), and the examples from my physics book only use algebra. I want to see some worked examples of actual physics problems that are modeled using calculus and differential equations, with enough explanation of the concepts involved so that I can link the concepts to the model. Thanks!OldTimeNESter (talk) 12:35, 18 August 2016 (UTC)

Hate to say this but:

Calculus is not distinct from Algebra

"F = m a" (where a is a vector) is the basis of Newtonian physics. And is an Algebraic form And so on. Newton's development of Calculus - requires use of Algebra. Acceleration is the first derivative of velocity, which is the first derivative of distance (by time). Collect (talk) 13:55, 18 August 2016 (UTC)

Well ok but I think OP wants a text book that includes e.g. integrals of time-varying forces, and goes beyond the simple cases used in many intro books, where the integral reduces to a simple multiplication, and the fact that there is integration behind the scenes is not even mentioned. I think I know the kind of book OP is talking about, it's commonly used for physics electives taught to non-science or non-hard-science majors, and does not have calculus as a prerequisite. SemanticMantis (talk) 15:23, 18 August 2016 (UTC)

I found Tipler's Physics for Scientists and Engineers to be great. Its latest edition is available for purchase. Which book are you presently using, and what issues are you finding? This feedback might help us find you a better book in a different style.

Nimur (talk) 14:00, 18 August 2016 (UTC)

If you are looking for introductory book, you might try Serway's Physics for Scientists and Engineers. It is easily understood and widely used college textbook at an introductory level. I would describe it more as "Physics with some Calculus" rather than "calculus-based physics". Most topics are introduced with algebra and then the book generally provides examples of how it would be used with calculus. In that way it is perhaps less intense than some other texts, but maybe that is what you would prefer? If you do choose Serway, look for one of the used editions. Used versions will save you a lot of money, and basic physics doesn't change so quickly that you need to read the most recent edition. Dragons flight (talk) 14:58, 18 August 2016 (UTC)

Do EpiPens actually expire and why?

Apparently the expiration date is six months after purchase, but do they still maintain their effectiveness after that?Timtempleton (talk) 17:03, 18 August 2016 (UTC)

If they tell you the expiration date is 6 months, then, you cannot expect that it works as it says on the can after 6 months. You would be using it at your own peril after this time.

However, pens that have been properly stored continue to have potency several years past the expiration date. If an emergency arises, it is better to use an outdated pen than to not to use it.--Llaanngg (talk) 17:08, 18 August 2016 (UTC)

BTW, notice that the expiration cannot be in reference to your purchase since they don't know when that will happen. They probably are allowed to sell epipens with at least 6 months official expiration date, but I am sure they last longer than that. Llaanngg (talk) 17:38, 18 August 2016 (UTC)

Is the expiration date printed on the device (or dose unit) itself, or on the scrip or separate instructions from the pharmacy? I just checked the prescription medications in my house, and almost all have a parmacy-label with a "discard after" date 1 year after the "filled" date. That's both for pills (where the pharmacy dispensed them from a stock that presumably has an exp-date according to its manufacture) and for prepackaged or single-dose-units. It seems coincidental that all different types of drugs would have a 1-year shelflife from exactly whatever date it was dispensed! A few have other dates, so it's getting transcribed from...somewhere...at least sometime. But the single-unit/prepackaged items have their own exp-dates on them, which is not the same as the 1-year-from-fill on the pharmacy-printed label. Fortunately, I could not find any cases where the product's own packaging had an earlier date than the pharmacy printed. DMacks (talk) 17:57, 18 August 2016 (UTC)

This is one of those troubling cases where you feel like someone's getting away with something disgraceful, but there's not much you can do about it. Mylan has drastically increased the price of the EpiPen (see here and here, for example). They have an obvious incentive to keep expiry dates short, in order to increase repeat purchases.

But on the other hand, maybe the contents do expire. Obviously we don't want people relying on unreliable pens; people could die.

I would love to see some genuine independent testing, under realistic conditions, maybe by someone like Consumer Reports, to see what actually happens to the contents and in what time frame. If such testing has been done, I would love to see a link to it. But obviously there is no way anyone here can responsibly say that it is OK to delay refilling a prescription. Even if we're not any too sure we trust Mylan. --Trovatore (talk) 18:26, 18 August 2016 (UTC)

By the way, it occurs to me that I was assuming, in the above, that Mylan has something to do with setting the expiry dates. I don't actually know whether that is true. Can anyone clarify on that point? --Trovatore (talk) 18:30, 18 August 2016 (UTC)

You may wish to search and see it their post-expiration effectiveness has been studied in the US Federal Shelf Life Extension Program. -- ToE 18:32, 18 August 2016 (UTC)

Outdated EpiPen and EpiPen Jr autoinjectors: past their prime? from J Allergy Clin Immunol. 2000 May. -- ToE 18:46, 18 August 2016 (UTC)

Interesting, tantalizing, frustrating link. The abstract says that the observed loss of potency after the expiry date is statistically significant — let me just point out here that that doesn't necessarily mean clinically significant. It just means that the observation would be unlikely to happen just by chance.

Similarly, it gives a correlation coefficient of 0.63 for the correlation between months past expiry date and reduction in potency. But that, by itself, doesn't tell you anything at all about how much potency is reduced per month. It just gives a measure of how much of the reduction appears to be systematic, as opposed to statistical fluctuation.

So we now know, with reasonable confidence, that potency drops past the expiry date, and keeps dropping. But we're basically none the wiser about whether that actually matters. --Trovatore (talk) 18:58, 18 August 2016 (UTC)

You could read the actual paper? [1] The key figure [2] seems to be showing a trend line with about a 40% decline at 90 months post-expiration, but with a wide variations (likely depending on how the material was stored). One sample lost 30% of activity only 12 months after expiration, another was almost 80% effective after nearly 80 months post-expiration. Dragons flight (talk) 19:27, 18 August 2016 (UTC)

Ah, I assumed you'd have to pay to get the full text. Thanks for finding that. --Trovatore (talk) 19:29, 18 August 2016 (UTC)

Indeed, extensive details are in the paper... but not everyone has zero-cost access to that journal. The paper may be purchased from the publisher via the web link. But even the abstract lists the authors' conclusion, which is to the effect that using an expired EpiPen may still be a better emergency-choice than opting not to administer any epinephrine at all. This is a really unique product, whose primary users are categorically emergency-users who do not have time to get an expert medical opinion. Nimur (talk) 19:31, 18 August 2016 (UTC)

All old articles (more than 1 year, I think) are free on the journal's website. I didn't login to get it. Dragons flight (talk) 19:42, 18 August 2016 (UTC)

• Drugs like these have complex chemical structures which degrade over time. Epinephrine. I have insulin pens with a 2017 use-by date that I got in 2015. Having lost 70 lbs, I don't use them any more, but they are still in the fridge in case having gotten drunk, I eat an entire blueberry pie.

I am not sure why this question is being asked here. The medicine is labelled. Are we expected as strangers on the internet to know better? If you want absolution to use it otherwise, seek professional medical advice from whomever prescribed or sold you these potential toxins. μηδείς (talk) 21:50, 18 August 2016 (UTC)

Grammar peeve: Should be "whoever", not "whomever". The case is determined by the fact that it's the subject of the relative clause, not the fact that the clause is the object of the preposition "from". You can remember it by remembering that it's the clause as a whole, not just the relative pronoun, that's subject or object of the larger sentence, but the relative pronoun by itself is subject or object of the relative clause. --Trovatore (talk) 23:49, 18 August 2016 (UTC)

I luvya, Trovatore. But no. If it is from whom, then it is from whom[ever]. The preposition from is determinant. μηδείς (talk) 01:53, 20 August 2016 (UTC)

I posted for a friend and there are some good answers here. Thanks all.Timtempleton (talk) 21:52, 18 August 2016 (UTC)

This was apparently triggered by news of stunning EpiPen price hikes announced August 17, 2016.[[3]].Timtempleton (talk) 22:43, 18 August 2016 (UTC)

@Trovatore: The patients have adopted a range of different tactics [4] - it is key to note that the "Epipen" is only one way of delivering epinephrine, and others exist even within the tiny universe of what the FDA allows. Another option described was for patients to go north and buy in Canada; apparently the savings more than pays for the tourism. They also mentioned Adrenaclick, which is apparently not a "generic epipen" because it works differently, but still is the same chemical for the same purpose. A big part of the fishing net here is simply deception. Wait, no, somehow the maker of Adrenaclick was induced to stop selling it; also Auvi-Q. [5] Wnt (talk) 10:53, 19 August 2016 (UTC)

The article Epinephrine autoinjector provides a source for the statement Units that have exceeded their expiration date can still be used in an emergency if an unexpired unit is unavailable and the solution is neither discoloured nor contains precipitates. AllBestFaith (talk) 13:16, 19 August 2016 (UTC)

Yes, that advice is in line with expired food. Food can go bad before or after the listed expiration date, as that's only an average based on typical usage. Looking for color changes, texture changes, separation, and smelling it are good methods for checking food, which we should do regardless of whether the expiration date has been reached. Of course, with food, they don't have as much incentive to shorten expiration dates, as people may just stop buying food with short expiration dates and buy something else. It's not a life-and-death situation. StuRat (talk) 19:55, 19 August 2016 (UTC)

Is a quadcopter capable of autorotation?

A quadcoptor like this. Imagine it might tumble due to it being top heavy so wouldn't it be better to position the rotors above the fuselage? ScienceApe (talk) 20:40, 18 August 2016 (UTC)

To perform autorotation efficiently (and to provide for a more safe touchdown speed), the helicopter must have the ability to control blade pitch. One of the common reasons engineers go for a quad-copter (instead of a conventional helicopter) is that they can build without variable pitch rotors; the vehicle control depends on providing differential power to each rotor, rather than using cyclic and collective. This applies whether the vehicle is very small or very large.

The emergency procedure for any specific design would need to be designed and published by the vehicle manufacturer.

The Helicopter Flying Handbook, Emergency Procedures chapter, describes the basic theory of autorotation, and explains the various applications of the technique for a "generic" helicopter.

Nimur (talk) 20:58, 18 August 2016 (UTC)

The above is mostly correct however the fact it has collective pitch is NOT what differentiates a "conventional" helicopter from a quad copter. There ARE now so called "3D" quad copters that also have collective pitch. They would presumably be capable of a auto rotation, however doing an auto rotation also relies on momentum of the blades, heads and engines, and since those are usually quite small on a quad copter so not sure whether it would actually work, might be one of those "depends" situations. My feeling is that it might not be impossible, but probably harder than with a "conventional" helicopter of the same mass. Though come to think of it, in theory I can't really see why 4 smaller blades that have the same lift as 1 big blade would be worse at autorotation. Vespine (talk) 23:36, 18 August 2016 (UTC)

Have a look at autorotation and read the chapter of the Helicopter Flying Handbook I linked. Aerodynamics is not intuitive: for a small-radius rotor, a greater percentage of the disc is in the stall regime during autorotation; consequently, small rotors yield faster rotor RPM without actually slowing the rate of descent.

Large rotors also have large blade rotational inertia. This is where the potential energy is stored, and that (plus your altitude, which is a rapidly decreasing resource) is your only reservoir of energy during a power-plant failure. You will want that reservoir to be as large as possible, especially when you are a foot or two above the ground.

"At approximately 1 foot AGL, apply upward collective pitch control, as necessary, to slow the descent and cushion the landing without arresting the rate of descent above the surface. Usually, the full amount of collective pitch is required just as the landing gear touches the surface."

Nimur (talk) 23:43, 18 August 2016 (UTC)

August 19

Why? (Dangerous medical advice on YouTube)

Why is dangerous and fraudulent medical advice allowed to be promoted on YouTube? This video encourages parents to shove dangerous chemicals up their autistic child's rectum to bleach away their autism! Autistic children are dying due to this promotion and YouTube is refusing to do anything about it! How is this legal? Mage Resu (talk) 02:23, 19 August 2016 (UTC)

Here is a link to YouTube Community Guidelines. If you feel that a video violates the rules, you can read about how to flag and report dangerous content. YouTube may choose to remove the video if its content is actually harmful, illegal, or even if it simply violates the standards that are expected by the YouTube moderators and community.

Just so we are clear: we (the volunteers who hang out at Wikipedia's science reference desk) can't directly control content or influence decisions made by YouTube; all we can do is point you toward YouTube's documented procedures for reporting "bad" content.

If the authors of these videos are actually making unfounded medical claims to market their product, that may be illegal in the United States. You can report a problem to the FDA, file a report of an unlawful sale of a medical product on the internet; or consult an attorney for further guidance. (If it is true that "children are dying," the link I provided includes an emergency telephone number that will connect you to a Federal investigator; and if it is not an accurate statement, you might want to proceed very carefully with your descriptions and phrasing when you file your report). To be clear, this is literally escalating to the level of "making a Federal case" out of the issue. The FDA can and will investigate such reports, and may pursue civil or criminal action against unlawful activity; but realistically, you shouldn't expect immediate resolution.

Nimur (talk) 02:30, 19 August 2016 (UTC)

Just for anyone wondering, this is about miracle mineral supplement. Someguy1221 (talk) 03:45, 19 August 2016 (UTC)

This is just the sort of bias I was talking about in my question. There are so many testimonials of MMS. It's proven effective. [[Vic]] 05:46, 19 August 2016 (UTC)

See snake oil. They use everything in the book, it's like "whack a mole", if they go to far and actually claim it's a medicine, then the authorities can act, and sometimes they do. But for the most part these weasels are VERY good at wording all their promotional material in such a way as to claim they aren't "REALLY" making any specific medical claims, *wink, wink*. I have been VERY deeply steeped in this specific subject, I've even shared communication with Jim Humble himself. HE him self never sells the stuff, he lives in the dominican republic far from the reach of any "western jurisdiction", he makes his money giving very expensive seminars and from "donations" to his "church". The greatest realization you can take away from this, is there are people, who are perfectly "normal" by all measures, not stupid or gullible, most even well meaning who are completely duped by this (and similar things like it), like quite possibly mr nowiki above me. They really believe this stuff works, they are swayed by the personal testimony, they've SEEN it with "their own eyes" and that evidence is better than anyone in a white coat could tell them. They don't care if it's a placebo, or a regression towards the mean, or treatment bias, or any number of other fallacious reason why it might APPEAR that something like MMS worked in the case they witnessed, those reasons require a very sound understanding of science and critical thinking which most "normal people" do not posses. Vespine (talk) 06:00, 19 August 2016 (UTC)

MMS is not snake oil! It works for me and it cured my son of vaccine damage! Many autistic sociopaths believe that it is a sin for me to want to cure my son! They think that being Mercury damaged is cool and is an alternate way of being! Let me ask you this, is having no friends, flapping your hands like an idiot, and constantly trying to kill yourself an acceptable way of being? Those vaccine damaged retards belong in a group home, not on the Internet! [[Vic]] 06:10, 19 August 2016 (UTC)

@Oppression of Suppression: Are you trolling or have you just been living under a rock? Thimerosal and autism is an explanation given post hoc for the MMR vaccine controversy, which is based on blatant fraud, lawyers paying for results to back up a lawsuit. Something causes autism but it's not a trace level of mercury - there's mercury all over in the environment, and believe me, there was a whole lot more of it the further back in history you look. There was nothing untoward forty or fifty years ago about kids playing with mercury, putting it on quarters, etc. every time a thermometer got broken, and they got broken all the time. Using the "miracle" cure to fix a problem that doesn't really exist to begin with is no proof at all. Wnt (talk) 10:26, 19 August 2016 (UTC) P.S. Not signing and then removing the autosignature and replacing it with something that doesn't link back to you is not the proper way to make Wikipedia postings, since it makes you uncontactable and unpingable without extra effort on our part. [sigh... someone already blocked him indefinitely for "disruptive editing" after like ten edits. Our admins don't even give people a chance. That doesn't mean he was making sense though.] Wnt (talk) 10:33, 19 August 2016 (UTC)

@Oppression of Suppression: Autistics are not sociopaths. No wonder they blocked you! Mage Resu (talk) 19:13, 19 August 2016 (UTC)

Videos extolling dangerous and fraudulent medical merchandise are pretty mild as controversial YouTube content goes. Months ago, I flagged a video describing how to make a firearm suppressor (a "silencer" in everyday-talk) out of a Mag-Lite flashlight casing, which is against Federal law, but YouTube has left it up. The funniest part of Steven Spielberg's "1941" is when Dan Aykroyd, playing the sergeant in charge of an anti-aircraft gun emplacement which had to be in a family's yard overlooking the coast, goes through the entire operating manual of the anti-aircraft gun, saying "You shouldn't touch the ordnance at all. But more specifically, you should never pull this hand-operating lever to the rear... Do not push a clip of ammunition down into the feed rollers here... You never restore this lever to firing position. Do not make sure that this cover is completely closed... Never depress operator's foot triggers here, here and at the rear here".

That's what the maker of the suppressor video did - describe in loving detail the things it's against Federal law to do to a flashlight to make it an illegal silencer, and exactly how to do them so that what you would have is an illegally-made device. But apparently YouTube's good with that.

Letting people sell vitamins that may or may not be horrible or claim they cure dread diseases is also probably contributing to commission of a Federal felony, but YouTube apparently has legal advisors who tell them it's all right. I had an Email chat with one of wikipedia's own attorneys on a related issue I won't describe, and he told me unless a publisher knows reasonably well that a publication describing dangerous things would be used to commit a bad act, it's legal. I agree, freedom of speech is worth defending, even when it's abused by the silly and cynical. I don't have to like those abuses, but they are a consequence of freedom - that it can be abused.

YouTube does allow people to post refutations of other people's videos - even if the poster of a video disables comments, you're able to make a video which says "you know this guy's video? It's crap. This is why....". And there have been some brilliant refutations of scientific fallacies posted on YouTube. loupgarous (talk) 11:48, 19 August 2016 (UTC)

@Vfrickey: This is actually on topic, since the question is "how is this legal?", though it belongs properly in Humanities. The answer is, obviously, that many of us do not condone censorship. Knowing how to build a suppressor is an exercise of both the first and second amendments to the U.S. constitution, and there is no reason why a private company, even if it has a nominal right to do so, should set itself at odds with the fundamental principles that its subscribers hold dear - or should, anyway. Now it may seem harder to justify this with a procedure that doesn't work, but the principle is actually the same whether you think something shouldn't be done or can't be done - it's still what you think. It's not up to some defender of scientific dogma to decide what is tolerable and intolerable belief, because however obvious you think that may be, in no time it will line up 100% with corruption and corporate interest. And given that even now believers in this crap claim that the truth is really on their side and being censored, what happens when you have that situation? Scientific truth requires falsifiability - if you can't read the explanation given, then you can't disprove anything, not even "miracle" "minerals". And it's not freedom of speech to say that people can say anything you agree with. Wnt (talk) 14:09, 19 August 2016 (UTC)

Awesome response! Wnt wins Wikipedia for today. --Trovatore (talk) 18:46, 19 August 2016 (UTC)

• So, the answer is that it's not a crime to give ludicrous and dangerous advice, as a rule (depending on jurisdiction), but it does invoke potential civil liability. Any identifiable person who advocates bullshit like MMS could be open to a civil suit if harm comes from following their advice. They could also be liable to intervention from social services if they are obviously harming their child. I would be very inclined to report any identifiable bleach enema advocate to social services in their locale. And any commercial entity promoting it, will probably fall foul of numerous regulations around truth in advertising and the sale of goods and services. That said, I think the reality-based community really needs to work on two websites: eBay and Amazon. Both sell merchandise and books promoting this bullshit. Amazon still sells the fraudulent diet book that landed Kevin Trudeau in jail, and still sells Robert O. Young's books despite the fact that he, too, is in jail. This is a real problem that should be addressed. Guy (Help!) 12:32, 19 August 2016 (UTC)

MMS, a solution of bleach and acid, sounds a bit like Dakin's solution, an antiseptic developed in 1914,and used to treat wounds during WW1.per Henry Drysdale Dakin. It was called the "Carrel–Dakin method of wound treatments". It consisted of "intermittently irrigating the wound with Dakin's solution. This solution is a highly diluted antiseptic, consisting of sodium hypochlorite (0.4% to 0.5%) and boric acid (4%)" They used Dakin's solution, at least in some modern formulation (not at all sure they would have used boric acid in it) on surgical dressings on me in the 1990s. I realize that sodium hypochlorite and sodium chlorite differ, but it is unclear what molecules are present when the chemicals are reacted with acids or whatever to prepare a clinical application. What is the concentration of MMS when it is actually swallowed, injected, or applied topically? The Sodium chlorite article says that it is mixed with acid to prepare a solution used on cow teats to treat mastitis. How does that solution differ from this MMS as applied to humans? Edison (talk) 13:54, 19 August 2016 (UTC)

Well, that's the problem - they're taking a chemical for external use because it kills anything and using it internally at concentrations hopefully low enough to not be obviously harmful. And using it to kill "autism", which doesn't really work because it's not a bacterium. Now yeah, this is biology, nothing is impossible, who knows if you can kick the immune system and have it turn on some neurons that should have died in development, right? Well, nothing's impossible but this is damn unlikely and there's no evidence for it and there's evidence it's a bad idea. Wnt (talk) 14:16, 19 August 2016 (UTC)

Edison asks how this product differs from (other products). Key to answering this question:

• The product is marketed with health claims, which is subject to regulation.
• The product is sold with instructions for use, and "when used as directed, produces an industrial bleach that can cause serious harm to health."

Many hazardous chemicals are sold in the United States. Down the street from my house, my local corner station sells chemicals known to cause cancer (gasoline and nicotine, in the same store!) But that store follows the rules for selling those products. Different rules apply when you are selling cigarettes, when you are selling gasoline, and when you are making a health claim to promote a medical treatment. The gasoline store can sell me gasoline, and if I want to believe, I am allowed to drink the gasoline in an effort to cure my ailments. But if a day ever comes when that gasoline shop puts a sign up instructing me to drink the gasoline, or claiming that drinking the gasoline cures the measles, the very same sale and transaction would cease to be legal. This is how our laws are written in the United States.

The issue of selling junk medicine isn't only a matter of the magnitude of the hazard, but it's also about the abuse of trust and the insidious predation on a segment of society who is desperate for help. That is one reason why our society more harshly penalizes a charlatan who sells fake drugs, but permits tobacco to be sold openly in stores. Them's the rules.

Nimur (talk) 15:16, 19 August 2016 (UTC)

Forget snake oil, what about ordinary cooking oil? Count Iblis (talk) 20:23, 19 August 2016 (UTC)

Watching this video gives the following questions: Why are conventional therapies anti parasites avoided? Why so many children and poeple shown? Why are these children infected with parasites? Are this abused children? Did anybody know if any of this children was feed with expired or contaminated food? It is known some microbe parasites are producing neurotoxines. Rats or mice trated with this neurotoxines began moving like some hyperactive children, not with straight back, not using the full foot to stand on and even some disorientated. In the former industrial age, workers did not need a personality. Today in the information and communication age, the personality is essential. This may come up with the question, was child mistreatment formerly ignored, but recognized today due personality is essential for work? I would not belive in any viral or information with advertising character, built on a single true fact, but avoiding all conventional treatment. If someone needs to hide his ass for child mistreatment, he might follow several false, inofficial or non-scientific information. --Hans Haase (有问题吗) 14:20, 20 August 2016 (UTC) --Hans Haase (有问题吗) 14:20, 20 August 2016 (UTC)

Excretion of Prednisone and Prednisolone

First and foremost, not looking for any medical advice, just curious (also, I don't think any of this would be medically relevant to anyone anyways). I know both of these, when taking prescription prednisone, are found in urine and breast milk, but I was curious about sweat and saliva (and any other sources). I was also curious for any information on how much is found -- if a patient is taking Xmg of prednisone, what amount of the substance is pharmacologically active in sweat, saliva, urine etc. (and in what concentration)? Thanks for any input73.174.196.36 (talk) 03:58, 19 August 2016 (UTC)

Apparently the infant will receive less than 0.1% of the prednisolone taken by the mother [6]. Someguy1221 (talk) 05:23, 19 August 2016 (UTC)

Interesting, since my mother has been told to take prednisolone for two years, and I saved her over $1,000 by finding a by-mail provider. I shall have to look into this tomorrow. μηδείς (talk) 01:45, 20 August 2016 (UTC)

Drugs: Nuvigil and Provigil

Are these drugs (Nuvigil and Provigil) considered to be amphetamines? Stimulants? Or what? 32.209.55.38 (talk) 04:24, 19 August 2016 (UTC)

A stimulant according to Armodafinil and a Google search.73.174.196.36 (talk) 05:08, 19 August 2016 (UTC)

According to our article Wakefulness-promoting Agent Nuvigil, Provigil and related drugs occupy their own pharmacological category, "eugeroics" or "wakefulness-promoting agents" within the general category of "stimulants". According to that article, as opposed to most other stimulants, wakefulness-promoting agents have a low or very low potential for abuse. loupgarous (talk) 12:11, 19 August 2016 (UTC)

Definitely not an amphetamine as the chemical structure does not contain the amphetamine skeleton. EdChem (talk) 16:26, 21 August 2016 (UTC)

Bias

OP has been blocked for disruption, soapboxing, etc. Move along. --Jayron32 11:55, 19 August 2016 (UTC)
The following discussion has been closed. Please do not modify it.
A few years ago, I attempted to correct a few biased statements on the Homeopathy article, only to be reverted repeatedly because my sources were "unreliable"! Why is Wikipedia so biased against alternative medicine? Is Big Pharma paying you to deny the effectiveness of homeopathy? With all the testimonies out there nobody without brain damage or a conflict of interest can deny the true power of homeopathy. I thought Wikipedia was editable by anyone, not just Pharma shills! Please explain. [[Vic]] 05:41, 19 August 2016 (UTC) This isn't the forum for disputing article content.--Savonneux (talk) 06:14, 19 August 2016 (UTC) I'm not disputing the content, I'm just asking why the bias is present! [[Vic]] 06:20, 19 August 2016 (UTC) It's just a variant of our here above "no medical advice". It's not a bias that homeopathy is a pseudo-science, it's a fact. The assertion that it "never works" or that "it's just by chance" is not entirely correct, but globally the cases where that critic would hold are so few and so minor that the opposite pile of the arguments and practices is overwhelmingly negative. Certainly without the biases which are inherent to Big Pharma itself the very tiny usefull bit of homeopathic medicine would be included in it. The good direction however is to encourage healthy growth of good medics populations, not to disperse them into factions. -Askedonty (talk) 08:07, 19 August 2016 (UTC) The OP seems to be here to "correct" our leaning towards factual information on homeopathy and bleach enemas. I have blocked this account until we have some indication that the angry mastodon behaviour will not continue. Guy (Help!) 09:26, 19 August 2016 (UTC) The opponents of homeopathy who say it does nothing are actually misinformed. Many homeopathic "medicines" are the most blatant kind of fraud, things which nominally are made up by taking some odd or grotesque substance and diluting it one to billions of billions of billions in water. But not all of them - you actually see things like "3X atropine" on the market, which is to say, atropine diluted 1:1000 and then diluted further in some customary but unspecified way to make pills out of it. Both niche items and mass market items like Zicam have ended up being reported for significant problems caused the the actual active ingredient. That said, the least-dilute homeopathy products, having the clear potential to do harm, also may have potential to do good; and sometimes, their ingredients seem well chosen for a chance of success. But they aren't tested the way that real medicine is tested, so it's a crapshoot. A key thing I would like to see with the big producers of ultr-diluted homeopathy products is what the inside of their business really looks like. There are companies that sell thousands of different highly dilute homeopathy products, each available in dozens of different dilutions. Do they actually have immense warehouses where they keep their diluted stocks prior to dispensing, or does a qualified homeopathicist dutifully shake and shake his graduated cylinders a dozen or more times each time the mark places an order? My bet is that if you went inside one of those places you'd find a faucet, a label printer, and a computer to print them up and bill people's credit cards! Wnt (talk) 10:19, 19 August 2016 (UTC)

For the pathologists

(Disclaimer: DO NOT read this question if you are the least bit squeamish)

OK, here is the question: Suppose that a bunch of terrorists invade a village and machine-gun every man, woman and child living there -- and then a few hours later, our brave heroes attack the terrorists and take the village back, but in the process they end up napalming part of the village. My question is, in this scenario would it be possible to prove beyond reasonable doubt whether the villagers died from the terrorists' bullets or from the napalm? (Inspired in part by the movie We Were Soldiers, and also by the third level of the Chinese campaign in Command & Conquer Generals.) 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 11:26, 19 August 2016 (UTC)

The pathologist will check the contents of the lungs. In your scenario they would find no napalm / fumes in the lungs. The blood from the wounds to the walls of the building would show a blood spray pattern different if they were standing, compared to lying down if they were shot after death. Graeme Bartlett (talk) 12:06, 19 August 2016 (UTC)

The link you're looking for is Bloodstain pattern analysis. We probably shouldn't redirect "spray pattern" because I could think of lots of uses for that term that have nothing to do with forensics or blood. But Bloodstain pattern analysis is the correct article in this context. --Jayron32 12:10, 19 August 2016 (UTC)

Relevant articles are Pathology and Cause of death. The latter article notes that the medical cause of death after acutely stressful events such as terrorism and military attacks is likely to be recorded as cardiac failure, brought on by Fight-or-flight response increasing heart rate through stress hormones.

Discovery of legal culpability for killings is the object of a forensic autopsy. Examination of bullet exit wounds may reveal how long bleeding, indicating a pumping heart, continued. From this and other information presented at an Inquest a Coronor will determine if possible the time of death, the exact cause of death, and what, if anything, preceded the death, such as a struggle. AllBestFaith (talk) 12:52, 19 August 2016 (UTC)

Sounds like The Liberation of Earth to me. Dmcq (talk) 16:46, 19 August 2016 (UTC)

This doesn't seem like advanced pathology to me. If you machine-gun a crowd to kill them all, there will be multiple bullets in each victim, passing through skull and other bone in many cases to leave forensic evidence so long as the bone survives at all. And of course the bullets themselves, after impact, remain in the buildings or soil. Enough napalm obviously can reduce much of corpses' softer tissues to an unrecognizable state, but the bones can survive a decent cooking and the bullets in the ground will survive more. You'd need a thorough cremation to reduce bones to such ash that they couldn't be examined (that article explains the need for the device known as a Cremulator, in fact...), and I don't think you can do that accidentally no matter how much napalm you dump on a town. Wnt (talk) 18:26, 20 August 2016 (UTC)

Thanks, all! 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 21:53, 20 August 2016 (UTC)

Homeopathy

Deja vu
The following discussion has been closed. Please do not modify it.
The Wikipedia article on Homeopathy claims that it is considered a "pseudoscience", even though there are plenty of people out there testifying its effectiveness at treating many ailments! Why is this? Smallness88 (talk) 23:47, 19 August 2016 (UTC) Lack of actual evidence! No double blinded placebo controlled studies demonstrate efficacy! The placebo effect accounts for all the anecdotal reports! Mage Resu (talk) 00:02, 20 August 2016 (UTC) As MegaMan points out, the placebo effect can explain this. But note that the placebo effect can itself be tested and has been found to be much more powerful than previously thought. Count Iblis (talk) 00:15, 20 August 2016 (UTC) We do not "claim" it is considered a pseudoscience". We state it is considered a pseudoscience because that is what independent reliable sources say (as indicated by the sources cited in the article). While the sources certainly discuss the evidence for and against efficacy and such, that is not part of whether or not we state that it is considered a pseudoscience. - SummerPhDv2.0 00:18, 20 August 2016 (UTC) Compared to Homeopathy, Chiropractic is practically miraculous and it's mostly fraudulent too. ←Baseball Bugs What's up, Doc? carrots→ 01:14, 20 August 2016 (UTC) They both could unite with the iridologists, colonic irrigationists, and Reiki healers and create an alternative hospital. I wonder how many would still go there when seriously ill. Hofhof (talk) 02:15, 20 August 2016 (UTC) What about all of these sources? Chronic obstructive pulmonary disease: Frass, M; Dielacher, C; Linkesch, M; et al. "Influence of potassium dichromate on tracheal secretions in critically ill patients." Chest. March, 2005;127:936-941. The journal, Chest, is the official publication of the American College of Chest Physicians. http://www.ncbi.nlm.nih.gov. Hayfever: Reilly, D; Taylor, M; McSharry, C; et al., "Is homoeopathy a placebo response? Controlled trial of homoeopathic potency, with pollen in hayfever as model." The Lancet. October 18, 1986, ii: 881-6. http://www.ncbi.nlm.nih.gov. Asthma: Reilly, D; Taylor, M; Beattie, N; et al., "Is evidence for homoeopathy reproducible?" Lancet. December 10, 1994, 344:1601-6. http://www.ncbi.nlm.nih.gov. Fibromyalgia: Bell, IR; Lewis II, DA; Brooks, AJ; et al. "Improved clinical status in fibromyalgia patients treated with individualized homeopathic remedies versus placebo." Rheumatology. 2004:1111-5. This journal is the official journal of the British Society of Rheumatology. http://rheumatology.oxfordjournals.org. Fibromyalgia: Fisher, P; Greenwood, A; Huskisson, EC; et al., "Effect of Homoeopathic Treatment on Fibrositis (Primary Fibromyalgia)," BMJ. 299(August 5, 1989):365-6. Childhood diarrhea: Jacobs, J; Jimenez, LM; Gloyd, SS. "Treatment of acute childhood diarrhea with homeopathic medicine: a randomized clinical trial in Nicaragua." Pediatrics. May, 1994,93,5:719-25. http://www.ncbi.nlm.nih.gov. ADD/ADHD: Frei, H; Everts, R; von Ammon, K; Kaufmann, F; Walther, D; Hsu-Schmitz, SF; Collenberg, M; Fuhrer, K; Hassink, R; Steinlin, M; Thurneysen, A. "Homeopathic treatment of children with attention deficit hyperactivity disorder: a randomised, double blind, placebo controlled crossover trial." Eur J Pediatr. July 27,2005,164:758-767. http://www.ncbi.nlm.nih.gov. Smallness88 (talk) 01:38, 20 August 2016 (UTC) Is there any reason to believe that the conclusions of all these article were positive? That is, have they shown homeopathy to be an effective treatment? Hofhof (talk) 01:59, 20 August 2016 (UTC) Why don't you read them and find out? Smallness88 (talk) 02:04, 20 August 2016 (UTC) Indeed, I did read some. And read the reviews of them too, which you appear to have skipped. So far, we still can conclude that homeopathy is biologically implausible because of the use of medicines diluted beyond the Avogadro limit. It is therefore reasonable to ask for a high level of randomized evidence before concluding that homeopathy exerts specific effects. The studies you linked above involve a relatively small number of patients. Hofhof (talk) 02:11, 20 August 2016 (UTC) Water has memory! Homeopathic dilutions are chemically different from pure water, because the original substance leaves an electromagnetic signature behind! The water "remembers" this electronic configuration! You should read about it! It's very interesting! — Preceding unsigned comment added by Smallness88 (talk • contribs) 02:16, 20 August 2016 (UTC) Water memory is the article for this. Electromagnetic signature seems to be a non-concept.Hofhof (talk) 02:20, 20 August 2016 (UTC) Article is biased! Smallness88 (talk) 02:23, 20 August 2016 (UTC)

August 20

Are engineers scientists?

Ignoring personal opinions about the definition and limits of each; just considering concrete decisions - like grants, fellowships, or prizes - do engineers count as scientists? Hofhof (talk) 01:53, 20 August 2016 (UTC)

What do you mean concrete decisions?--Savonneux (talk) 03:58, 20 August 2016 (UTC)

That is, when someone has to draw a line as to who gets rejected or accepted. I mean when it comes down to apply and receive a grant for scientists, or a prize for the best minority female scientist, would engineers be considered a part of the scientists? Hofhof (talk) 04:13, 20 August 2016 (UTC)

"Science" grants are infinitely broad in what each one could possibly be for, they aren't the exclusive domain of scientists though (anything practical tends to be an engineering problem). The difference between engineering and pure theory is just that, engineers are mostly concerned with applied science (how do we use science to solve this problem) and "scientists" are mostly concerned with the purely theoretical.--Savonneux (talk) 04:28, 20 August 2016 (UTC)

While it's true that engineers are concerned with how to use science to solve problems, it's not true that scientists are mostly concerned with the theoretical. They also do empirical observations, such as observing fossils or supernovae, and they do experiments. Then they or other scientists come up with theories to explain the observations and results. Loraof (talk) 16:00, 20 August 2016 (UTC)

Agreed. The person asking seemed to want a sort of differentiation so I was trying to show the only one. Anyone who applies rigorous logic to a thesis is technically a scientist.--Savonneux (talk) 00:24, 21 August 2016 (UTC)

The problem is that the word engineer is very difficult to define. The man who comes to repair my washing machine calls himself an engineer, but so do the men who designed and built the space shuttle and the new Forth road bridge. In the USA the driver of a train also calls himself an engineer. Some may deserve to be called scientists - others probably do not. Wymspen (talk) 14:05, 20 August 2016 (UTC)

Origin of "engineer":[7] ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:31, 20 August 2016 (UTC)

I'm in A BIG CITY and I can't see the stars at night due to light pollution. If there was a...

I'm in A BIG CITY and I can't see the stars at night due to light pollution. If there was a countrywide powercut, how long would it take for the light pollution to go away? and the stars to be viewable? Like, would it be instant or would it take several years? Since light is really fast I can't understand how it would stay in the sky for very long once the lights went out. Please explain. — Preceding unsigned comment added by 200.94.21.194 (talk) 14:28, 20 August 2016 (UTC)

A tiny fraction of a second after the power cut, most of the light pollution would vanish. A small amount would remain because of emergency generators etc, but the effect would appear instantaneous. Air pollution is a separate factor to consider in some cities. Dbfirs 14:42, 20 August 2016 (UTC)

See Light pollution for our article; Adaptation (eye) might also be useful. Although the light pollution would be gone as soon as the power went off, it would take some time (about 20-30 mins, according to our article) before the observer's eyes could take full advantage of the darkness. Tevildo (talk) 14:56, 20 August 2016 (UTC)

I'm not so sure if you'd necessarily need 20-30 minutes or how strong the effect would be. Our Accelerating dark adaptation in humans seems in some ways better then the adaptation one, but even so, both primarily talk about moving from high illumination to low. If you were indoors in a light room, you may need 20-30 minutes. But how significant would the effect be if you were already in a dark area of the city (i.e. where there are no lights clearly visible). Sure the sky would still be bright, but I'm not sure how big the difference would be after adaptation for 20-30 minutes. If you were sleeping in a dark room with your eyes closed, provided you're careful when getting out (i.e. red light etc), the difference would probably be even less. So IMO the issue may be less related to light pollution but more what you were doing before. (Or in other words, it's quite similar to if you're living in an area with minimal light pollution except that you can't normally predict when a nationwide powercut will happen.) Nil Einne (talk) 15:31, 20 August 2016 (UTC)

Thing is that the difference between optimal dark adaption and partial dark adaption is only going to be noticeable when you try to spot hard to see objects at the very limits of visibility, like spotting M81 with the naked eye. Count Iblis (talk) 17:10, 20 August 2016 (UTC)

Supernova ice ages and artificial substitutes

I've been reading articles lately [8][9] that suggest that supernova debris, as evidenced by iron-60, might have set off the Pleistocene ice age. There is some mismatch - the iron-60 started 2.7 million years ago, and continued for a million years, but why isn't the correspondence exact, or at least entirely inclusive of the glaciated period? How viable is this idea. And if it is viable .... how much material are we talking about here? I shouldn't think a supernova 300 or more light years away would rain down very much matter on Earth to increase its cloud cover. So is it possible for humans to cook up a space probe that does the same thing, as a sort of geoengineering to counter excessive global warming? (Not that I'm suggesting this is necessarily a good idea... sometimes I wonder if the 'Gaian' purpose of humans was to look around and figure out how to clear out all that nasty ice...) Wnt (talk) 18:57, 20 August 2016 (UTC)

Ok, this is a really back of the envelope calculation, and I could be off by several orders of magnitude. They are hypothesizing a supernova 300 light years away, ish. Let's pretend it's a big star with 8 solar masses. Even if we pretend the entire mass of this star explodes outward, the earth will only catch a small fraction of the material. How small? Well, by the time the blast front reaches earth, it has spread out over a spherical region 300 light years in radius, and the space in that surface occupied by the earth is only 1e31 of the whole, so that's the fraction of the star we capture. That would be about a kilogram of material. Now, maybe Earth's gravity will pull in some material that is not headed directly toward us, but these particles are moving very fast, so probably not a whole lot more. I think even if I'm way off on some things (if the star is closer, or bigger) it's still going to work out to a truly negligible amount of matter. I honestly just don't see how this could possibly affect Earth's weather. Now a much much closer supernova, however (less than 50 light years) could make a noticeable dent in the ozone layers, and the effect on plankton could have some long-range ecological consequences. Someguy1221 (talk) 10:00, 21 August 2016 (UTC)

This is why there shouldn't be that much kryptonite on Earth. Terrestrial planets must be at least ~10⁵ times smaller than 8 Sun masses so there should only be a few grams of kryptonite in the entire world if Krypton exploded anywhere near the speed of Alderaan. Sagittarian Milky Way (talk) 20:16, 21 August 2016 (UTC)

what is this filter?

hello, in the discrete-time PLL example here there are these lines:

% Implement a pole-zero filter by proportional and derivative input to frequency
filtered_ersig = ersig + (ersig - lersig) * deriv;
% Keep error signal for proportional output
lersig = ersig;

In simple terms, what kind of filter is this (other than pole-zero and, I assume, FIR, as it doesn't use past output samples)? Apparently what the filter does is that whenever there is change, it creates an "overshoot" in the direction of the change and then settles on the new value. Is it then a high-pass? Thanks in advance! Asmrulz (talk) 20:06, 20 August 2016 (UTC)

A cursory search suggests that a 'pole-zero filter' is an approximation of a Butterworth filter, which our article describes as a theoretical ideal for a "maximally flat magnitude filter". 2606:A000:4C0C:E200:296A:CC64:7945:8C5F (talk) 03:47, 21 August 2016 (UTC)

That's not quite right... a Butterworth filter is a specific type of filter. "Pole-zero" is a design methodology to create a filter by placing poles and zeros - mathematical constants in the denominator and numerator of a transfer function. One can use pole-zero analysis to build a filter of any specific type. A "pole-zero filter" is any filter whose properties were designed by placing poles and zeros explicitly, instead of computing them using some other method. Every filter has poles and zeros: but many times, because we have a different analytical technique, we may choose not to concern ourselves with the values of the poles and zeros. In this case, the author described this code-snippet "pole-zero filter"; I would call it a "PD-controller"; but in any case, those comments are just a little bit of English language verbage to help motivate this very small mathematical sub-expression of the larger PLL system. Nimur (talk) 14:11, 21 August 2016 (UTC)

The code excerpt is meaningless without context - but if you look at the full code in the article, it makes a little more sense. This is a digital filter, and it saves state, so although the history (previous samples) aren't explicitly stored, the filter is using their values.

The filter is neither a high-pass nor a low-pass filter. Instead, it outputs a control signal whose magnitude and sign are proportional to frequency error. A reference signal, of known frequency, is compared to an input signal, of unknown frequency. This particular implementation uses the trick of edge-detection, using a digital, bitwise comparator to trigger the edge detection; and it keeps a running sample-counter to estimate how synchronized the two signals are - in other words, how coherent their phases are. In the analog world, we would use a totally different method.

Mathematically, any filter that converts a frequency to a different frequency (in this case, to a "dc" control signal) is definitionally non-linear: loosely speaking, frequency is not preserved. You can not think in terms of "frequency" pass-bands. This is not a low-pass, high-pass, or band-pass filter: it is a filter whose output depends on input frequency (and phase) in a nonlinear fashion.

This is a complicated bit of code - and it stores digital state in many variables, including the signal flags and the "it" (iteration counter) variable. If we want to throw mathematical terminology at this software implementation, we could say that because these state-flags allow us to compute results that are related to previous samples, they are functions of the derivative of the input signal. Although the code doesn't directly compute and store the derivative (difference between current- and previous- sample), the algorithm does make implicit use of the derivative.

Again, if you tried to formally write out that relation, it would be a non-linear differential equation - and what this software filter does is to try to numerically solve it! Like all non-linear differential equations, the solution is only valid in special cases: if you fed a junk input signal in, with really high noise levels or just completely the wrong frequency content, you could cause the PLL to fail to converge (and this is a real thing that does actually happens in real-world electronics applications)!

Nimur (talk) 14:11, 21 August 2016 (UTC)

Thank you so much! I think I "get" it (to the extent it's possible to "get it" without the theory and the associated math.) I'm just (still) trying to make an all-digital PLL as a hobby project (that I could flash onto the ATtiny.) I wrote a simulation in which I incorporated bits and pieces from the code in the PLL article. It seems to work well (I'm not trying to replicate the 4046 chip.) Even frequency multiplication works if I put a divider in the "feedback path." Thanks again! Asmrulz (talk) 20:02, 21 August 2016 (UTC)

Are all PLLs actually PID? That not all PID have frequency as the controlled quantity, is obvious, but from cursory googling, noone seems to discuss PLL in terms of PID, and no PLL block diagrams I've seen contain explicit P, I and D sections, like here. Asmrulz (talk) 20:28, 21 August 2016 (UTC)

No, it is possible to build a phase-locked-loop circuit that does not use a PID controller at all, but uses a different type of digital controller. It is also possible to build a PLL that is completely implemented in analog circuitry. For example, in the analog world, we can build a PLL using a varactor (if we want to pretend like it's 1970!), or using a voltage-controlled oscillator or using a Miller topology feedback control amplifier. In digital designs, PIDs are a fundamental building-block: it's such a convenient, commonplace design methodology that you will surely see it in lots of places. Moral of that story: learn the theory and practice of PID controllers really deeply, and learn to recognize the implementation and the behavior of PID controllers; because they show up as tiny building-blocks inside lots of more complicated systems.

Once you get really good at the math and the theory, you will be able to turn any control equation into an "almost-equivalent" PID controller... once again, "PID" is really just a design-methodology that lets us write a specific type of equation - a second-order digital control transfer function - in a standard, canonical form. Once the equation is in standard form, we can use shortcuts to solve for its behaviors and estimate its properties, and we can "plug and chug" into standard software or hardware implementations. That is meant to be easier than finding full solutions to the stability and control equations for every single sub-problem you encounter in a complicated design.

Nimur (talk) 20:52, 21 August 2016 (UTC)

August 21

Different number of heart valves in the heart sides

I've taken the liberty of transferring this question from Wikipedia talk:Reference desk Wnt (talk) 02:06, 21 August 2016 (UTC)

Is there any logical explanation why in one side of the heart (right) there are 3 valves -triquspidal, while in the second side (left) there are 2 (mitral)? Tov17 (talk) 21:56, 19 August 2016 (UTC)

This discussion has been closed. Please do not modify it.
The following discussion has been closed. Please do not modify it.
You should post this Q to the Science Desk. This is the talk page where we discuss problematic questions. StuRat (talk) 22:01, 19 August 2016 (UTC) When you're there, they may explain that the heart has only four valves, not five. ←Baseball Bugs What's up, Doc? carrots→ 23:43, 19 August 2016 (UTC) If you provide an answer when someone asks in the wrong place, you not only encourage more misplaced questions, you encourage others to answer in the wrong place. Please stop doing that. --Guy Macon (talk) 03:24, 20 August 2016 (UTC) And, more importantly, please stop giving wrong and unreferenced answers to questions which you are obviously unqualified to answer. The human heart has six valves: the bicuspid valve, the tricuspid valve, the aortic valve, the pulmonic valve, the coronary sinus valve and the eustachian valve. The eustachian valve has no known function after birth, leaving five functional valves in the normal human heart. Additionally, about 80% of people have a vieussens valve of the coronary sinus, which could be counted as a sixth (or seventh) heart valve.--William Thweatt TalkContribs 05:12, 20 August 2016 (UTC) Four "main" valves, as noted in Heart valve and two other valves as you note. As to the OP, there's nothing stopping you from moving the question there yourself, if you're so concerned about it. Also, amidst your nannyistic scolding, you did not actually answer the OP's question. Way to go. ←Baseball Bugs What's up, Doc? carrots→ 07:55, 20 August 2016 (UTC)

I suspect the question that the OP meant to ask is the one answered at [10]. - Nunh-huh 08:36, 20 August 2016 (UTC)

Indeed, thank you. Tov17 (talk) 17:45, 20 August 2016 (UTC)

What the OP tried to ask is why the tricuspid valve has three leaflets while the bicuspid valve has two. The tricuspid separates the right atrium and ventricle while the bicuspid separates the left atrium and ventricle. Well, the answer is that it's complicated - we don't know the full network of biological and regulatory processes behind morphogenesis of any system in the level of detail needed to really give "why" type answers to these sort of questions with confidence. We can say that they're different and show particular factors which if altered might alter whether they are different, but I'm skeptical we've even gotten to that point, though properly I ought to look it up. But in this case the situation is a little weirder and a little simpler - the number of leaflets or cusps in the tricuspid can vary from two to six. Here's a reference that argues they are fundamentally divided in two: [11] So the difference in the anatomy is subtle - subtle enough that it might readily be ascribed (but this would be purest speculation, and probably wrong) to properties like how much resistance there is from lungs versus somatic tissue, or asymmetric development of the heart as a whole. Wnt (talk) 02:15, 21 August 2016 (UTC)

This discussion has been closed. Please do not modify it.
The following discussion has been closed. Please do not modify it.
You and Nun-huh have it right. Macon and FGF do not. ←Baseball Bugs What's up, Doc? carrots→ 23:13, 21 August 2016 (UTC) Yes, the OP was confusing number of valves with structure of valves. ←Baseball Bugs What's up, Doc? carrots→ 19:22, 21 August 2016 (UTC) The OP wasn't confused at all. He made it crystal clear which part of the heart he was talking about. You simply didn't bother looking up "tricuspid" and "mitral" before answering. --Guy Macon (talk) 21:45, 21 August 2016 (UTC) You're wrong, I did. And the OP agreed that Nunh-huh's link answered his question - which you didn't bother trying to do. So shut your own valve. ←Baseball Bugs What's up, Doc? carrots→ 21:57, 21 August 2016 (UTC) The OP explicitly mentioned the vales they were asking about. The question was unambiguous. You were clearly wrong. Stop answering questions you haven't got a clue about. It wouldn't hurt to look up the word 'civility' while you're at it. Fgf10 (talk) 22:08, 21 August 2016 (UTC) You, lecturing others about civility? That's funny. You pop in here to fire shots at others rather than answering the OP's questions. You're of no use here. Go back to ITN and nominate some more frauds for the "recent deaths" column. ←Baseball Bugs What's up, Doc? carrots→ 22:23, 21 August 2016 (UTC) "The most hostile group was the one with high but unstable self esteem. These people think well of themselves in general, but their self-esteem fluctuates. They are especially prone to react defensively to ego threats, and they are also more prone to hostility, anger and aggression than other people. "These findings shed considerable light on the psychology of the bully. Hostile people do not have low self esteem; on the contrary, they think highly of themselves, But their favorable view of themselves is not held with total conviction, and it goes up and down in response to daily events. The bully has a chip on his shoulder because he thinks you might want to deflate his favorable self image." Source: Roy F. Baumeister, Evil: Inside Human Violence and Cruelty, p 149 --Guy Macon (talk) 22:34, 21 August 2016 (UTC) The perfect description of someone who comes here to attack other editors. ←Baseball Bugs What's up, Doc? carrots→ 23:05, 21 August 2016 (UTC) You're literately making no sense at all. The question was already correctly and exhaustively answered (no thanks to you) in the end. I'm not even active on ITN any more. I think you might need a holiday away from here. Can some passing admin just close this nonsense down? And preferably refer BB to ANI while they're at it....? Fgf10 (talk) 23:46, 21 August 2016 (UTC) I applaud you for abandoning ITN. But before you return to the ref desk, if ever, be sure to come here for the sole purpose of answering an OP's question. ←Baseball Bugs What's up, Doc? carrots→ 23:53, 21 August 2016 (UTC)

Using plastic glove as condom

Can you still get a girl pregnant if you use a plastic glove as condom? — Preceding unsigned comment added by 107.214.148.164 (talk) 18:53, 21 August 2016 (UTC)

Even regular condoms are no guarantee against pregnancy, though they reduce the odds. But when used with spermicida foam, it's very near zero percent chance. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:20, 21 August 2016 (UTC)

What about plastic gloves used with spermicide? — Preceding unsigned comment added by 107.214.148.164 (talk) 19:25, 21 August 2016 (UTC)

Just get free condoms somewhere. The condom won't be like 3 inches long either. Sagittarian Milky Way (talk) 19:46, 21 August 2016 (UTC)

Condoms are specifically tested to make sure that they are strong enough not to tear or leak when used during sexual intercourse. Rubber gloves are not tested for that, so are less likely to be safe. Wymspen (talk) 20:23, 21 August 2016 (UTC)

There are actually a lot of gloves that are sold without any strong guarantee against breakage. The usual idea with lab gloves is merely to keep something sanitary given gentle usage, where not keeping it sanitary is no big deal. Often they're labelled as being for "comfort" or such, rather than being surgical gloves. Our article on Medical gloves talks about people who do double-gloving even with high-quality latex gloves. Some people who do work where glove integrity would be critical, like using hydrogen fluoride solutions, actually do without gloves but simply wash their hands after each and every potential contact because they fear the effect of an unseen leak. I can tell you for sure that with the usual cheapest-of-the-lot lab gloves that people use for non-critical scientific procedures, holes are not even uncommon. Of course, condoms aren't entirely impenetrable either, but at least they're designed to do one thing and do it as best as possible. Wnt (talk) 20:56, 21 August 2016 (UTC)

Add to it that plastic gloves (or the powder within it) are not tested for allergic reactions when used this way. Latex gloves and latex condoms are also made from a different type of latex. Llaanngg (talk) 20:59, 21 August 2016 (UTC)