Wikipedia:Reference desk/Archives/Science/2015 March 17

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March 17

Gender detection via pulse checking

In the Korean drama Sungkyunkwan Scandal, there is one scene (albeit dreamed up & not part of the actual plot) where the female main character, while disguised as a male, faked an illness in order to avoid following the monarch's orders, which caused the monarch to summon a doctor; the doctor then checked "his" pulse near the wrist and immediately realized that "he" was female. Is this realistic in real life - in other words, are trained traditional Asian medical practitioners really able to detect a patient's true gender simply by checking their pulse without taking off the patient's clothing? 98.116.73.98 (talk) 05:26, 17 March 2015 (UTC)

No. Or I highly doubt it in any case. But someone familiar with anatomy might see other subtle clues from which they could fairly reliably guess the gender: How hairy their arms are, whether they have an adam's apple, the length and shape of fingers, etc. Alone, those things fall within a range, where a female with above average hairy arms would have hairier arms than a male with below average hairy arms, but taken together, barring "outliers" like very effeminate males, I think a doctor probably could tell an average female trying to disguise themselves as a male just by looking at them fully clothed. Vespine (talk) 05:42, 17 March 2015 (UTC)

As seen in this doc an average 18 yo female has a resting heart rate almost 10 beats/min higher than a male of the same age. This, combined with the factors Vespine mentioned, would at least allow one to guess the gender of the patient, although the test's error rate will be pretty high (esp. considering that the doctor was measuring the pulse of a supposedly ill person, which would provide an alternate explanation for the presumably higher heart rate). Abecedare (talk) 05:48, 17 March 2015 (UTC)

Fitness has even more effect on resting heart rate. This page (granted not as "scientific as the above) has the male vs female difference not as high, it says average 18 year old male is 70-73 and average female is 74-78, a "below average" male is 74-81 and an above average female is 70-73, and "above average" isn't a "great" difference, there are then still: good, excellent and "athelete" categories which are even lower for females. Vespine (talk) 23:25, 17 March 2015 (UTC)

It also depends on the fitness level expected of the male and female elite. The males may be expected to have martial prowess, whereas females might be trained in more sedate activities. LongHairedFop (talk) 14:39, 18 March 2015 (UTC)

I suspect that this is related to traditional Chinese medicine, which seems to place great emphasis on the pulse and distinctive male and female pulses are bound up with the concept of yin and yang. Alansplodge (talk) 18:23, 20 March 2015 (UTC)

Frostbite

I was just looking at Facebook and noticed that someone was asking about what sort of lotion or cream was good for frostbite. They got replies such as Aveeno, Vaseline, Nivea cream, Penaten and make a hole in a Vitamin E capsule and pour it on the affected area. I looked on Google but very few of those seem reliable. This seems OK and says don't put any on it. I also thought that the University of Maryland Medical Center would have been OK until I saw the "Complementary and Alternative Therapies" and then realised that it was part of their Complementary and Alternative Medicine Guide. What I am wondering is if any of the things mentioned on the FB would be of any use? I've had frostbite several times on my face in the last 40 years but I've never actually put anything on it. The only reason I could think to do would be after several days, when the dead skin had dried up and was peeling. By the way this is not a request for medical advice. It's just curiosity and I have no intention of telling them what they should be doing. Also I just noticed the Maryland link says that depression will put you at risk for frostbite, why though? CambridgeBayWeather, Uqaqtuq (talk), Sunasuttuq 09:59, 17 March 2015 (UTC)

The more serious versions would require medical treatment, but the least serious result of exposure to cold might just be drying and cracking of the skin, which can be treated with a moisturizer. A thick moisturizer, like Vaseline or Bag Balm, would require fewer applications.

As for depression, if the person isn't in a mood to do much of anything, then doing the things it takes to prevent frostbite might fall into that category. StuRat (talk) 11:07, 17 March 2015 (UTC)

True frostbite is were the skin/muscle has been frozen long enough for it cells to die (as opposed to getting a few little white points of skin through carelessly handling dry ice etc.). If the cells are dead then there is no point in applying anything to make it better. However, a prophylactic treatment to prevent complications like a bacterial infection setting in may be in order – especially if it is serious. Applied creams may stop the dead stuff desiccating and leave one with the equivalent of Petri dish on your face, feet or wherever -ugh! Most of are alive today because even peeling skin still acts a a good bacterial barrier. In addition to StuRat comment about depression, exhaustion can also lead to periods of self-neglect too. So the OP could do well to ask his medical practitioner on how to treat frostbit in all its degrees, because this is often one of those injuries, where when it happens there is not doctor around for miles and miles. We don't give medical advice here but he can ask his GP if it is a good idea to carry around something like Dettol.--Aspro (talk) 14:28, 17 March 2015 (UTC)

Thanks. I don't really need to see a doctor as the main thing is to not get frostbitten at all. Over the years I've frozen my ears, nose and cheeks several times. It can be quite painful as they thaw out. Nowadays I'm usually more careful. I've also frozen my fingers a few times and that's caused nerve damage. It was just that I'd never really seen anyone wanting to put anything on it. Of course there is always the possibility of gangrene which will require a doctor. Oh yes Dettol isn't available here plus it would probably freeze unless carried on you rather than in your grub box. CambridgeBayWeather (mobile) (talk) 21:52, 17 March 2015 (UTC)

I have to ask why you've gotten frostbitten so many times. I understand it's freakin' cold there, but it isn't so cold that no amount of protective gear can prevent frostbite, is it ? (I can kind of understand the fingers being frostbitten, as sometimes you can't do what you need to do with thick gloves on, like getting a key in a lock.) StuRat (talk) 06:44, 21 March 2015 (UTC)

I think I can answer that Stu. Our ancestors came out of Africa. Our bodily feed-back is for those climes. Frost-bite can so easily creep upon us expatriate African primates without us being aware. One learns this by experience- and so take the necessary precautions. Although the OP may consider himself now acclimatized, my suggestion to find out more from a professional, was because he might come come across someone who is new to the region and suffers 'serious' frost bite. Knowing the right thing to to do in those situations is very useful if medical help is hours and hours away. P.S. Bye the way: Is Cambridge Bay one of those places in the the US that still enforce prohibition. If so, I will strike it off of my vacation list – nothing personal but I can't finish the day without a good vermouth. --Aspro (talk) 15:04, 21 March 2015 (UTC)

Cambridge Bay, Nunavut is in Canada. StuRat (talk) 22:12, 21 March 2015 (UTC)

Well that is north of Detroit and I grant you - a shade over the border. So its back on my vacation list of places to go to before I die. Wonder if CambridgeBayWeather can fix me and the family up with a reasonably priced igloo for a fortnight. (I will bring my own bottle of Dettol ;¬)--Aspro (talk) 22:27, 21 March 2015 (UTC)

Measuring g with a pendulum

It's clearly easy enough to measure $g$ with a pendulum as the frequency depends on the length of the pendulum and $g$. My question: why bother doing it for different pendulum lengths? Why not just use one length? I'm helping someone with a report on this very point, but I don't see any merit in using different lengths of pendulum.--Leon (talk) 13:19, 17 March 2015 (UTC)

The problem is which length does everybody agree should be the standard length. In other words: does one decide upon a yard, meter or a length that give a period in seconds. And how did one accurately define a second before the acceptance of the caesium standard anyhow(?) since the speed of the Earths rotation changes whereas the yard and meter should not (in an ideal world). Having said that however, by using pendulums of a different length it proves the theory that pendulums can agree on a reliable and repeatable way to measuring $g$. --Aspro (talk) 13:52, 17 March 2015 (UTC)

Second#History explains a bit about how seconds were measured prior to the 1997 adoption of the caesium standard. (Also has some good info and links related to the OP's question) Short answer - first subdivision of days, then non-pendulum clocks, then pendulum clocks. I've heard that one's own heart rate/pulse was often used by researches in the Age of Reason - Huygens was contemporary, but his clocks probably had low market penetration for the first few decades. SemanticMantis (talk) 14:34, 17 March 2015 (UTC)

Also, did the OP google Wikipedia pendulum length first? That has more info too...Pendulum#Standard_of_length. --Aspro (talk) 14:50, 17 March 2015 (UTC)

Well, the other reason for doing multiple pendulum lengths is in good experimental design. How does one know that the relationship between frequency and length is linear? You'd need multiple data points to determine that. --Jayron32 14:57, 17 March 2015 (UTC)

reincarnation

Hello, now, is there someone who reincarnates? 雞雞 (talk) 14:17, 17 March 2015 (UTC)

Reincarnation will tell you you a decent amount about the topic. SemanticMantis (talk) 14:35, 17 March 2015 (UTC)

It may be worth considering that while reincarnation with paranormal recall of events from specific past lives is an unscientific idea, I am not aware of any scientific argument to distinguish the qualia experienced by one individual from those experienced by another. For example, there is no scientific determination of whether a person who has the corpus callosum cut has "two souls" or one; nor whether the bridging of the gap between brains via other nerves in conjoined twins or via some other means would make them "the same person" or not. Science can measure only the ability to communicate and recall information, which is a distinct ability since of course we all may fail to recall even what "we ourselves" have seen. Wnt (talk) 03:35, 18 March 2015 (UTC)

How much tar does the food contain?

How much tar does 1 cup of black tea drink contain? How much tar does 1 cup of coffee contain? How much tar does 1 cup of milk contain? How much tar does 100 grams of meat contain? How much tar does 1 medium egg contain? How much tar do the vegetables contain? How much tar do the fruits contain? — Preceding unsigned comment added by 88.235.209.56 (talk) 15:36, 17 March 2015 (UTC)

How do you know any of these items contain tar? ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:02, 17 March 2015 (UTC)

As our article on tar explains, it is a mixture of hydrocarbons and carbon produced by heating certain types of plant matter. Untreated plants don't contain tar. In cigarettes the tar is produced by the process of smoking it. Looie496 (talk) 17:03, 17 March 2015 (UTC)

So it's at least conceivable coffee might have trace amounts of tar, since the roasting of beans could achieve some destructive distillation to make tar compounds. Other things that people commonly eat that might have tar: maybe molasses or soy sauce? What about roasted vegetables? Couldn't they have traces of carbon/hydrocarbons brought out by heat? I don't know enough food science/chemistry to understand if enough pyrolysis occurs during processing to make tar in those foods, but it seems reasonable... this [1] is not terribly reliable, but it does claim that coffee, roasted grains, and some roasted vegetables can contain tar. SemanticMantis (talk) 18:21, 17 March 2015 (UTC)

I had the exact same thought about coffee potentially containing tar due to the roasting process, but searching around I didn't find any source that says that this is an actual concern. According to Cofee:Physiology (page 351), while coffee heated to 350°C was shown, back in 1938, to produce "coffee tar" containing harmful 3,4-benzpyrene, regular coffee roasting doesn't go beyond 200-220°C and the 1938 experiment is thus, "of interest from a historical and academic perspective view [sic?], but has no practical validity". The chapter has much more details on later experiments, with the bottom line being that brewed coffee has 3,4-benzpyrene conc. of < 1 ng/kg, which is not considered undue. For comparison, an average person ingests 250 ng of benzpyrene per day, mainly through oils, fats, and cereal ie equivalent of 2000+ cups of coffee!.

Side note: the work linked previously, which SemanticMantis also tags as "not terribly reliable", is by Herbert M. Shelton and is particularly untrustworthy. Abecedare (talk) 17:41, 18 March 2015 (UTC)

Skin disinfection prior to needle insertion

When my blood was sampled recently, the nurse did not disinfect the skin first as I recall being done when I was much younger. I'm pretty sure this has happened before in the recent past as well. Has this disinfection step (using an alcohol wipe in the past, IIRC) been done away with at some point? Country of residence is the United Kingdom. --92.6.114.195 (talk) 17:56, 17 March 2015 (UTC)

I take it you understand if you have specific concerns about your treatment, you should contact your health care professional or other relevant contact point. In terms of general recommendations in the UK, this vaccine green book on the UK government website recommends that visible dirty skin be cleaned with soap and water, but that it's otherwise not necessary to clean the skin [2]. This patient.co.uk guideline [3] specifically recommends against using alcohol swabs, or really any swabs, although one of the reasons isn't relevant for non vaccines. This [4] suggests the actual policy depends on the specific NHS Trust. While these all relate to injections, I'm not sure it's any different for blood samples. For example, not an RS but [5] includes comments relating to the UK where it's suggested cleaning of some sort may be recommended in for cannulation (although I'm not sure there's even agreement on that) or for glucose tests, but not for general simple in and out needle insertions. Nil Einne (talk) 19:09, 17 March 2015 (UTC)

If someone failed to swab my skin before bringing the needle forward, I would get up and leave. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:53, 17 March 2015 (UTC)

And what is your evidence source that cleansing is necessary Bugs. Richard Avery (talk) 08:10, 18 March 2015 (UTC)

Common sense. Better safe than sorry. And standard practice in American medicine. You can't know what microbes might be lurking on your skin, eager to enter an open wound. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:19, 18 March 2015 (UTC)

Apparently, it's not that obvious whether to swab or not to swab. "Both disinfection prior to skin injections and omission of disinfection were followed by (almost) no infections" in [6]. The Straight Dope provides a further rationale for swabbing, explaining why previously to lethal injection the arm still gets swabbed: "Apart from its usefulness as an antiseptic, alcohol causes blood vessels to rise to the surface, making it easier to insert the needle. More important, there's a chance the prisoner's sentence might be delayed or commuted at the last minute." [7] --Noopolo (talk) 13:07, 18 March 2015 (UTC)

• I take an injection of Gila monster-venom once weekly. The nurse who told me how to inject it told me to wipe the injection spot off with alcohol, then to wipe off the alcohol so the injection doesn't sting as much! I think the main concern is probably with things like Staphylococcus aureus which are very common on the skin and in the mucosa, but which wreak havoc if they reach the bloodstream. μηδείς (talk) 18:09, 18 March 2015 (UTC)

Soul and neuron action potentials -- A follow-up

In regards to the recently archived thread on Soul and neuron action potentials begun by Brandmeister, in the headlines today was an article summarizing a report in Cell: "Even worms have free will. If offered a delicious smell, for example, a roundworm will usually stop its wandering to investigate the source, but sometimes it won’t. Just as with humans, the same stimulus does not always provoke the same response, even from the same individual."

From Cell: "We found that the collective state of the three neurons at the exact moment an odor arrives determines the likelihood that the worm will move toward the smell. So, in essence, what the worm is thinking about at the time determines how it responds.... It goes to show that nervous systems aren't passively waiting for signals from outside, they have their own internal patterns of activity that are as important as any external signal when it comes to generating a behavior."

μηδείς (talk) 20:06, 17 March 2015 (UTC)

What's the question? Vespine (talk) 23:17, 17 March 2015 (UTC)

Read the entire header beyond the first five words and the first sentence, including the link. I have emphasized them for your ease. μηδείς (talk) 00:44, 18 March 2015 (UTC)

There was no question, or indeed a point. The quoted has nothing to do with the fictional concept of a 'soul' 131.251.254.154 (talk) 13:22, 18 March 2015 (UTC)

I am not about to quote the entire past thread or to modify the archives. The OP asked how neurons could act spontaneously, rather than being governed solely by their inputs from other cells. If you are not interested, fine, you don't need to comment. But If you are interested, just reading the headlines won't help, go back and read the thread that was archived on the 15th. μηδείς (talk) 17:57, 18 March 2015 (UTC)

Studying souls in worms sounds like a job for a Jainist. If I program a robot to turn toward the smell of gasoline 70% of the time, does that mean it has a soul? Free will is, like qualia, like the soul in general, a paranormal phenomenon. You cannot measure whether someone has free will. No matter whether random or deterministic, mechanical systems do not create free will. IMHO (and no other, to my knowledge, and despite/because of the paradox implied) the capacity for free will, like other paranormal phenomena, depends on precognition of the fixed and unchangeable future. Wnt (talk) 14:19, 18 March 2015 (UTC)

I have no interest in arguing this, ("soul" was the OP's word, not mine) but animals do have volition, the ability to act without or despite external stimuli. That's why Buridan's ass doesn't starve. That's what the worm article is about. (The use of "free will" is a little bit sloppy from a philosophical standpoint.) And calling it "free" will is simply the recognition that we hold healthy adults responsible for their uncoerced volitional actions. Volition is a biological phenomenon, free will is a moral and legal concept. Neither has to do with metaphysics. μηδείς (talk) 17:57, 18 March 2015 (UTC)

The worm has no free will. Higher animals do. Free will, it is when a living creature creates a sequence of images, models in his mind/brain with a few possible outcomes and chooses one of them depending on circumstances. And still there are situations when the brain snaps and takes a route that according to calculations was not optimal. All decisions including primitive ones in the worm nervous system with three neurons are done on quantum level and quantum operations have intrinsic property to be unpredictable. This unpredictability may be low and the chance that the worm will turn away from the food source/smell may be very small but such things do happen. --AboutFace 22 (talk) 23:22, 18 March 2015 (UTC)

Free will was the term used by the reporter analyzing the actual paper in my link. The paper says, "in essence" the action is determined by what the worm is "thinking about". The Caenorhabditis elegans brain has some 302 neurons and 7000 synapses, but is the nonlinear (my word) interaction of these three neurons which determines whether the animal will veer towards the smell of isoamyl alcohol.

I agree with your point that speaking of free will is at best metaphorical on this level, but again, mere volition and the uncoerced morally responsible choice of experienced adults are two different things. The worm does indeed have a rudimentary form of volition. I agree quantum mechanics has its effects, but even if we just treat this system classically, it will develop chaotic behavior. But I think it's only the dualist notion of the mind-body dichotomy that makes us attempt to attribute free will to mysterious forces. μηδείς (talk) 00:39, 19 March 2015 (UTC)

The totality of all living tissues is inanimate in the same way as individual organs and tissues are, like neurons or blood vessels. If you had all organs and tissues assembled together to form that roundworm (or any other organism), it still wouldn't live. The nervous system which controls movements in most animals is also inanimate, which implies the existence of an external input to produce volition signals for it. In that sense, the organism acts rather as a medium for processing such volition neuron potentials, not as their origin. Brandmeister^talk 10:15, 19 March 2015 (UTC)

That's simply not true. All cells are alive until they senesce. There is no point at which the egg and sperm, fertilized egg, fetus, child or adult is an inanimate lump of dead flesh, although some outer layers like skin and hair are composed of once-living but now dead cells. See cell theory. I despair of trying to teach you biology 101 on line, but I posted this link to show you that the internal states of cells are just as important as externally generated action potentials. You seem to be channeling Aquinas and his idea that ensoulment begins with quickening (i.e., that the baby first kicks once it gets a soul). That might be relevant in a debate on abortion, but at no point is there an animated thing which becomes animated. μηδείς (talk) 17:16, 19 March 2015 (UTC)

The cells are alive as long as they are supplied with energy. You can isolate one cell, but it will live as long as you take care of it. Even non-cellular life in the form of viruses requires a more complex host to thrive. A single cell isn't the same as the simplest living being. In most animals the sustainability of cells requires neuron potentials which trigger the necessary movements for energy resupply (feeding and drinking). As you know, humans and some other animals can voluntarily starve themselves to death (hunger strikes, etc), ignoring related internal stimuli and as such not producing the required neuron potentials. Where do such volitions come from? Obviously, not from cells, despite being mediated by them. Brandmeister^talk 20:04, 19 March 2015 (UTC)

You seem to be taking a snapshot in time, ignoring the past and the context, and providing borderline cases. Yes, someone can choose to self-immolate or starve. But they have to get to that point due to prior experiences and choices. A woman I use to know by the name "Cat" used to say, between stimulus and response lies choice. In any case, the heart begins to beat spontaneously, and the entire development of an embryo is effected by the migration of cells and their electrochemical interactions. There is never any point at which the body is dead, and a soul is needed as a Re-Animator. μηδείς (talk) 05:31, 20 March 2015 (UTC)

Yes, but the point is that who or what makes the choice? During a knee reflex, for instance, your organism makes the choice, not you. During a hunger strike, for instance, you make the choice, not your organism. In other words, a healthy person can distinguish between the neuron potentials triggered by his/her organism and the neuron potentials triggered directly by him/her (an external input, not coming from the organism itself). Brandmeister^talk 11:06, 20 March 2015 (UTC)

Well, that clarifies it. You are claiming that you are not your "organism". You are introducing the supernatural as your premise, which I reject. I hold that I am my body, and all its attributes, one of which is the faculty of consciousness. Unless you are going to change your mind on the notion that you are not your organism, there's nothing that will satisfy you, even your pineal gland. μηδείς (talk) 16:26, 20 March 2015 (UTC)

Labia Human only?

The Wikipedia article on the Labia seems to make the presumption that this anatomical feature is only something that occurs in humans, is this correct?Naraht (talk) 20:14, 17 March 2015 (UTC)

I suspect the (fallible) contributors to the article unconsciously assumed that no-one would be interested in nonhuman labia. I'm not going to web-search this topic on a work computer, and being still at work can't check the authors and title of a book I have at home, but it's a detailed and scholarly work about Orangutans, which includes photos of genitalia, so I can give you only an an unreferenced assurance that, yes, they at least do have them (if female). Perhaps someone else can contribute online references. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 20:24, 17 March 2015 (UTC)

WP:SOFIXIT. If Wikipedia is missing some knowledge, and that is something that bothers you, you're not only allowed, but politely requested, to fix the problem. --Jayron32 20:34, 17 March 2015 (UTC)

If I had the information I would do so, however I asked here because I don't have the information.Naraht (talk) 20:51, 17 March 2015 (UTC)

If you don't have an answer Jayron, why reply? If the OP knew the answer, they would probably have added it already. They don't, so they very reasonably ask here. Naraht, although vaginal anatomy varies between species, most mammals have a labia-like structure. As for the human bias in the article, this is disappointingly common, almost all anatomical and biochemical articles are almost exclusively human focussed. I would be a mammoth task to bring some balance to them. Fgf10 (talk) 07:37, 18 March 2015 (UTC)

Of course, you're correct with that. I apologize sincerely to the OP and to any other readers for my uncalled for rudeness. It is unacceptable, and you all deserved better. --Jayron32 12:47, 18 March 2015 (UTC)

Development of the labia is deeply intertwined with development of the scrotum and glans penis, since these are dual-use tissue progenitors. I know for example spotted hyena have labia and have a surprisingly male-like development, essentially a female scrotum and penis (which of course is not the case in related species). So the structure's evolution goes pretty far back, but right now I'm drawing a blank on exactly when. Wnt (talk) 03:21, 18 March 2015 (UTC)