Wikipedia:Reference desk/Archives/Science/2016 December 5
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December 5
[edit]What is the difference between these two glycines?
[edit]I saw these two illustrations in the article Glycine: and I don't understand what are the differences between these two structures. If it's the same molecule why they are different while using skeletal structure?
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/46/Glycin_-_Glycine.svg/220px-Glycin_-_Glycine.svg.png)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Glycine-zwitterion-2D-skeletal.svg/220px-Glycine-zwitterion-2D-skeletal.svg.png)
93.126.88.30 (talk) 00:07, 5 December 2016 (UTC)
Thank you. I know what is zwitterion but I'm not talking about the plus and minus signs that make it zwitterion. I am talking about the structure. It says that there are here TWO types of skeletal structure with different positions with different number of elements (H3N vs.NH2) 93.126.88.30 (talk) 02:11, 5 December 2016 (UTC)
- There's not a different number of elements. The H3N+ (or NH3+, if you want to more easily compare to NH2) is just the amine group protonated with a hydrogen. What had been a COOH is now a COO-, as it lost a hydrogen when it was deprotonated. The skeletal structure doesn't appear any different either. The second structure is merely rotated about 45 degrees clockwise from the first structure in space, but the connectivity is identical. It's as if you picked up the entire physical molecule, rotated it, and set it down. The central carbon is still SP2 hybridized. The only difference is, as TenOfAllTrades said, that the second structure is the zwitterion form. --OuroborosCobra (talk) 03:21, 5 December 2016 (UTC)
- The neutral and zwitterionic forms are tautomers. The only difference is the location of one of the protons.
- Your "variant 1" is the neutral form that is often quoted for simplicity, even though it actually won't occur at standard conditions: any pH high enough to deprotonate the –NH3+ group to –NH2 will also deprotonate the –COOH group to –COO−. At biological pH, the amine is protonated and the carboxylic acid is deprotonated, giving your "variant 2". Double sharp (talk) 03:28, 5 December 2016 (UTC)
- There is no chemical meaning for which side of the N the H are written ("H2" on the right of the N in variant 1 vs "H3" on the left of the N in variant 2). In both cases, and as always for condensed formula details, "adjacency implies connectivity". The bond from the implicit carbon of the CH2 group goes to the N specifically, so the nitrogen is obviously bonded to that carbon. The 2 or 3 H are written condensed and adjacent to the N, so they are bonded to it. The N has tetrahedral geometry regardless, so there is not an "H2" or "H3" group, nor are the set of N–H bonds all going in any one direction. DMacks (talk) 06:16, 5 December 2016 (UTC)
Reducing the waiting period to donate blood after male-male sex - practical impact?
[edit]Here in Australia, the rules state that a male cannot donate blood for a full 12 months after engaging in anal sex with another male. Many have argued that such a long period is unnecessary - it could be reduced to three months with no risk (feel free to disagree if I've somehow got the science wrong). The "window period" for modern HIV tests is never longer than that, as far as I am aware, and in many cases is shorter.
two questions:
1. Less important question: Would there be any safety risk to the blood supply in terms of avoiding HIV transmission, by reducing the exclusion period after male-male sex from twelve months to three?
2. This is my more important question: How much would such a move practically increase the donor pool? I would assume that the majority of men who have anal sex with men (I avoid the term "gay", as not all such men would identify with the title) would generally not do so on a one-off, or only once a year. Men who engage in this activity would, in general, I assume, tend to do so on a regular basis (i.e. significantly more frequently than once every three months). I know many answers here will be speculative, but I still believe it's a fair question: How many men are excluded by a one-year exclusion period, who would not be excluded by a three month exclusion period? How much of an impact would such a move have on donor numbers and blood stocks? Would it be significant at all? Or would it be trivial, making any rule change have little practical impact?
I don't think any of the answers to this question would potentially fall into the "medical advice" prohibition, as those who make the rules on these matters are at zero risk of taking advice from wikipedia! And the second question is not really a "medical" one in any case. Eliyohub (talk) 09:57, 5 December 2016 (UTC)
- According to the UK's blood service, the 12-month window is to do with Hepatitis B rather than HIV - see the "Why a 12 months deferral?" section here. AndrewWTaylor (talk) 10:08, 5 December 2016 (UTC)
- Hardly a reason - we've had vaccination against Hepatitis B available for many years now. Assuring a donor's vaccination is up to date, no need to defer them at all due to Hepatitis B - they're at near-zero risk. Besides, the reference you provided only says it takes up to 12 months to clear the virus. The window period to potential detection is far shorter, up to six weeks. In addition, if a person tests positive to Hepatitis B "surface antibodies", it indicates that not only are they free of the virus, they are immune (either due to vaccination, or recovery from past infection) Eliyohub (talk) 10:47, 5 December 2016 (UTC)
- It's my impression that when these policies were first drawn up, it was surmised that there were other bloodborne diseases (like "non-A, non-B hepatitis", i.e. mostly hepatitis C) which were not understood, and there was some thinking that there were other unknown risks being addressed. Mixed, of course, with a certain amount of prejudice. There are some other curiosities that have emerged since like GB virus C that may justify a certain amount of ongoing paranoia, though one hopes that the number of diseases circulating undetected is falling. In general the blood banking system needs to think about both known and unknown threats - that said, there may well be different specific criteria to use that secure against them more effectively. Wnt (talk) 11:02, 5 December 2016 (UTC)
(EC) I found [1] which I think is the most recent review of the behavioural based donor deferral criteria in NZ. It mentions a 6 month deferral was considered but rejected based on what was felt was insufficient evidence that it wouldn't increase the risk. It also mentions other things like why more detailed sexual history (e.g. condom usage) was rejected (again insufficient evidence and what limited evidence there was caused concern as well as concern over whether such questions may be too invasive), why oral sex is included, etc. One thing it does mention is that the older 5 year period was at least partially due to concern over new TTIs. However it doesn't sound like the 12 month period was based on that.
I make no comment on the decisions and accuracy of the information contained in the report, except to note that it says the maximum window period is for hepatitis C which is 94 days. While it doesn't seem there's good evidence sexual activity is a strong risk for hepatitis C infections (except for certain co-occuring infections), since there is some limited evidence it may be the case that a conservative risk assessment would consider 3 months too short. The report does mention that in addition to the window period + margin of error for the test just in case, there is also concern over making the margin of error too short in case people don't remember correctly. Note it would seem easily possibly relying on people to remember if they've been properly (including all courses) remember if they've been vaccinated against Hepatitis B would raise similar concerns although I'm not sure if this arises since it doesn't seem Hepatitis B has the worst window period, e.g. Human T-lymphotropic virus 1 also has a longer window period.
Also the report makes it sound like in some countries (but not NZ anymore) there may be concern over a failure to remove a sample with a positive test result (quarantine failures/release errors). While improving systems to prevent this would be the primary goal, in the mean time reducing detected infections (by removing riskier individuals) may also be implemented to reduce the risk of TTIs, and this was evidently part of the reason for the old 5 year deferral.. Finally the report does mention 6 months was recommended by the blood service in Australia but rejected by the TGF. It is also was implemented in Japan and maybe elsewhere (I didn't look that well). I suspect you can probably find some info on why the TGA rejected the 6 month deferral. It also seems likely that if research in those countries where 6 months was adopted suggests it didn't result in an increase in TTIs, this would be then spread, as the report and other things I've read suggest this is what happened with 12 months.
Nil Einne (talk) 14:38, 5 December 2016 (UTC)
- [2] is the TGA's decision rejecting the 6 month proposal. Nil Einne (talk) 14:45, 5 December 2016 (UTC)
- That letter uses the jargon of "compliance" and describes some statistics -- what I *think* it means is that based on their statistics, the men are having sex more often than they recollect, and they are afraid that if men don't think they had sex in six months it will actually be less. (They admit that a shorter period "might" improve compliance, but say that isn't proven). Wnt (talk) 13:17, 6 December 2016 (UTC)
- [2] is the TGA's decision rejecting the 6 month proposal. Nil Einne (talk) 14:45, 5 December 2016 (UTC)
- It's my impression that when these policies were first drawn up, it was surmised that there were other bloodborne diseases (like "non-A, non-B hepatitis", i.e. mostly hepatitis C) which were not understood, and there was some thinking that there were other unknown risks being addressed. Mixed, of course, with a certain amount of prejudice. There are some other curiosities that have emerged since like GB virus C that may justify a certain amount of ongoing paranoia, though one hopes that the number of diseases circulating undetected is falling. In general the blood banking system needs to think about both known and unknown threats - that said, there may well be different specific criteria to use that secure against them more effectively. Wnt (talk) 11:02, 5 December 2016 (UTC)
- Hardly a reason - we've had vaccination against Hepatitis B available for many years now. Assuring a donor's vaccination is up to date, no need to defer them at all due to Hepatitis B - they're at near-zero risk. Besides, the reference you provided only says it takes up to 12 months to clear the virus. The window period to potential detection is far shorter, up to six weeks. In addition, if a person tests positive to Hepatitis B "surface antibodies", it indicates that not only are they free of the virus, they are immune (either due to vaccination, or recovery from past infection) Eliyohub (talk) 10:47, 5 December 2016 (UTC)
- In the US, ever having had an active case of viral hepatitis permanently excludes one from donating blood. Part of the justification is that a small percentage of infections never clear but have a viral load that persists indefinitely at a low concentration. Of these, a small percentage have traces of a hepatitis virus (usually HBV) but no longer produce sufficient antigens or antibodies to be detectable during a standard blood screen. Dragons flight (talk) 14:06, 5 December 2016 (UTC)
- I've just seen that we have an article on the subject, and also that the 12-month rule is being reviewed in the UK. AndrewWTaylor (talk) 14:22, 5 December 2016 (UTC)
- From men who have sex with men, at least 2.9% of US men (age 15 to 44) had sexual activity with another man in the previous 12 months. [2.9% is the self-reported frequency, the authors believe that such activity is unreported due to perceived bias.] I don't think it is controversial to suggest that most people who have sex try to do so frequently, so much of that 2.9% are probably going to excluded by any choice of waiting period. I would guess that moving from a 12-month wait to a 3-month wait probably wouldn't increase the potential donor pool more than ~1%. Dragons flight (talk) 15:26, 5 December 2016 (UTC)
- Cheeses, Murray and Joseph! I am HIV and Hep A, B, & C, negative, as well as negative for Syphilis, Gonnorhea, and Chlamydia. But I have still been told never to donate blood, given I have had three full transfusions. We do NOT give medical advice, please read WP:DISCLAIMER and then go elsewhere, like to a physician! μηδείς (talk) 04:33, 6 December 2016 (UTC)
- None of the above is medical advice, μηδείς, It's a response to questions about medical regulations and the medical theories and knowledge surrounding them. There is no suggestion whatever that anybody either is or is not going to undergo or avoid any medical procedure as a result of it. {The poster formerly known as 87.81.230.195} 176.248.159.54 (talk) 04:56, 6 December 2016 (UTC)
- Thank you IP. μηδείς, sometimes you do go too far. I made it clear in my question that those who make actual decisions on these matters are at zero risk of taking advice from wikipedia. Presumably, you did not decide whether or not you would be allowed to give blood - the relevant medical regulator did! (Perhaps your case is an exception,ifs it involved question of your own health, not that of the recipient. But where a potential recipient's health may be at stake, as is the issue in the regulations I ask about, the decision is never left to the donor, or anyone liable to be influenced by the discussion taking place here). Eliyohub (talk) 12:42, 7 December 2016 (UTC)
- None of the above is medical advice, μηδείς, It's a response to questions about medical regulations and the medical theories and knowledge surrounding them. There is no suggestion whatever that anybody either is or is not going to undergo or avoid any medical procedure as a result of it. {The poster formerly known as 87.81.230.195} 176.248.159.54 (talk) 04:56, 6 December 2016 (UTC)
Nil Einne, thanks for your answer. Two issues. One, re vaccination for Hepatitis C B, there is no need to rely on donors correctly remembering if they've been vaccinated - testing for "surface antibodies" will give this info as to immunity entirely accurately, as I mentioned in an earlier reply. I had such a test myself, for reasons unrelated to blood donation. My understanding is that such a test is no more expensive than a standard Hepatitis B test, and is in fact done by some clinics as a standard component of such tests.
Second, is there any info as to either a) What percentage of the male population have had sex with another man during the last 12 months, but not during the last 3 months, and b) did the cutting of the waiting period in Japan and any other jurisdictions which implemented it lead to any increase in donations? Eliyohub (talk) 13:12, 7 December 2016 (UTC)
- I think your first comment is confusing Hep B and Hep C. There is no Hep C vaccine, and unlike Hep B, the typical antibody test for Hep C doesn't distinguish between an active infection and a previously recovered infection. Dragons flight (talk) 13:30, 7 December 2016 (UTC)
- OH, you are correct, I meant Hep B! Struck out now and corrected. You are correct about Hep C, there is no vaccine, nor any simple test to distinguish between an active infection and a past one. Ergo, anyone who ever had Hep C is usually permanently excluded from donating. However, in my first comment near the very beginning of this question, I explicitly referred to Hep B. What I HAD intended to say this time was, as part of his response, Nil Einne mentioned the possibility that when it came to Hep B again, people might not correctly remember whether they've received the full course of vaccination, and I was replying that this is not a concern, it can be tested for. As I said, I agree with you that concern over Hep C is a different story, and a real issue, although as Nil Einne mentioned again, the degree to which it can be spread sexually is debatable. Eliyohub (talk) 14:05, 7 December 2016 (UTC)
Why are mitochondria called "mitochondria"?
[edit]I understand—from both the Wikipedia article and the Wiktionary article—that the word mitochondrion is constructed from the classical Greek for "thread" and "granule." My question is, why thread and granule rather than, say, potato and tennis racket?
I can guess that a mitochondrion's gross morphology may have stricken its discoverer(s) as particularly discrete and grain-like. I can also speculate that its strands of DNA may have stood out to the microscopically aided eye. But I know better than to trust my guesswork on a matter about which I am so far from expert.
Could someone please illuminate? And to clarify, although I do welcome guesses better educated than mine, what I'd really love is an authoritative explanation of what actually did inspire the namer, rather than merely what might plausibly have done so.—PaulTanenbaum (talk) 14:08, 5 December 2016 (UTC)
- Read this. --Jayron32 14:13, 5 December 2016 (UTC)
- (ec) See Carl Benda: 'Because of their tendency to form long chains, he coined the name mitochondria'. AndrewWTaylor (talk) 14:17, 5 December 2016 (UTC)
- Wow, in a mere 5 minutes I got exactly what I'd requested. Thanks!—PaulTanenbaum (talk) 14:28, 5 December 2016 (UTC)
Is that claim proved scientifically?
[edit]I saw this video which is viral on Facebook and it claims that the way that people sit on the lavatory seat is not correct and not healthy and the correct way is like animals or as people used to do in the past (read the titles on the video). My question is if it's proved scientifically or it is nonsense? 93.126.88.30 (talk) 15:43, 5 December 2016 (UTC)
- There is some evidence that squatting reduces the amount of straining needed, but at the same time, it's also more difficult than sitting which seems to counteract the benefit. This study, for instance, actually finds squatting seems to increase stroke risk, and advises that at risk of stroke avoid it. Smurrayinchester 16:09, 5 December 2016 (UTC)
- We have an article on this at Defecation postures, but it isn't a very good article.
- There is also a video on this on youtube that I found to be hilarious.[3] Also see [4]
- But enough of the silliness. What do the sources say?
- "Conclusion: The results of the present study suggest that the greater the hip flexion achieved by squatting, the straighter the rectoanal canal will be, and accordingly, less strain will be required for defecation." --Influence of Body Position on Defecation in Humans (Full text here:[5])
- "The patients were instructed to defecate using two types of toilet: an unraised, ground-level style (common in Iran), and a bowl with attached tank style (common in Western countries) ... Use of the Iranian-style toilet yielded a much wider anorectal angle, and a larger distance between the perineum and the horizontal plane of the pelvic floor than the European style. Bowel evacuation was also more complete using the Iranian-style toilet" --Impact of ethnic habits on defecographic measurements
- "The magnitude of straining during habitual bowel emptying in a sitting posture is at least three-fold more than in a squatting posture and upon urge. The latter defecation posture is typical of latrine pit users in underdeveloped nations. The bowels of Western man are subjected to lifelong excessive pressures which result in protrusions of mucosa through the bowel wall at points of least resistance." --Etiology and pathogenesis of diverticulosis coli: a new approach.
- "In conclusion, the present study confirmed that sensation of satisfactory bowel emptying in sitting defecation posture necessitates excessive expulsive effort compared to the squatting posture." --Comparison of Straining During Defecation in Three Positions: Results and Implications for Human Health (Full text here:[6])
- "Cardio-vascular events at defecation are to a considerable degree the consequence of an unnatural (for a human being) seating defecation posture on a common toilet bowl or bed pan. The excessive straining expressed in intensively repeated Valsalva Maneuvers ... adversely affecting the cardio-vascular system is the causative factor of defecation syncope and death. The squatting defecation posture is associated with reduced amounts of straining and may prevent many of these tragic cases." --Cardio-vascular events at defecation: are they unavoidable?
- "A considerable proportion of the population with normal bowel movement frequency has difficulty emptying their bowels, the principal cause of which is the obstructive nature of the recto-anal angle and its association with the sitting posture normally used in defecation. The only natural defecation posture for a human being is squatting. The alignment of the recto-anal angle associated with squatting permits smooth bowel elimination. This prevents excessive straining with the potential for resultant damage to the recto-anal region and, possibly, to the colon and other organs." --Primary constipation: an underlying mechanism.
- "Our result clearly shows that modified commode squatting posture has the highest success rate for the treatment of chronic anal fissure." --Role of defecation postures on the outcome of chronic anal fissure
- On the other hand, see the comment above mine for a study on blood pressure in hypertensives during squatting. Also, I can't help but wonder whether it makes a difference whether you squat with a toilet seat supporting your body, as seen in the squatty potty video above, or whether you support your weight with your legs/feet, as is don in Japan. --Guy Macon (talk) 18:16, 5 December 2016 (UTC)
Nice answers! thank you all 93.126.88.30 (talk) 17:06, 7 December 2016 (UTC)
Arachidyl Alcohol
[edit]Arachidyl alcohol page isn't clear on this. Is this substance always derived from groundnut (peanut) oil? And if so, can it cause an allergic response in someone who has a peanut allergy? --TammyMoet (talk) 17:09, 5 December 2016 (UTC)
- Regarding the second question: that would depend on whether or not the person was specifically allergic to this compound. The source of a pure compound makes no difference. It would only cause an allergic reaction in one of two cases: 1) if a person were specifically allergic to this compound or 2) if the compound was laced with impurities that the person WAS allergic to. This article lists the specific molecules that are known to trigger peanut allergies. Arachidyl alcohol is not listed there, they are mostly all proteins. --Jayron32 18:34, 5 December 2016 (UTC)
- Thank you Jayron that's actually really useful. --TammyMoet (talk) 18:43, 5 December 2016 (UTC)
- Well, there is a caveat that no compound you can buy is truly a pure compound; it can have exceedingly high purity, or then again, maybe not. A cold pressed peanut oil can contain allergens, according to that article. It is hard to imagine a purification scheme that concentrates the 1% arachidic acid present in peanut oil, then a chemical reduction to arachidyl alcohol, which leaves peanut allergens intact (these being low molecular weight proteins).[7] Nonetheless, they are water soluble and resistant to heat, so at least conceivably you could have a trace present but your scheme to extract the alcohol pulls them along and then they oil out and become concentrated at a key step... I'm not going to say impossible, and I doubt anyone can since the question is potentially open-ended for any conceivable synthesis approach. That said, the bulk of peanut oil, and the purest and cheapest stuff to use for this purpose, starts non-allergenic before you even begin trying to make or purify the alcohol. It's probably more likely some idiot drops a bag of peanut shells into the oil and they have to strain them out with cheesecloth than the allergens make it through purification. And Cupuaçu has something around six times more arachidic acid than peanut oil, and is "unlikely" to cause peanut allergy. :) Wnt (talk) 19:37, 8 December 2016 (UTC)
- And, of course, if it's made from ethylene (as I described), then the whole allergy thing becomes a moot point. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 10:44, 9 December 2016 (UTC)
- Well, there is a caveat that no compound you can buy is truly a pure compound; it can have exceedingly high purity, or then again, maybe not. A cold pressed peanut oil can contain allergens, according to that article. It is hard to imagine a purification scheme that concentrates the 1% arachidic acid present in peanut oil, then a chemical reduction to arachidyl alcohol, which leaves peanut allergens intact (these being low molecular weight proteins).[7] Nonetheless, they are water soluble and resistant to heat, so at least conceivably you could have a trace present but your scheme to extract the alcohol pulls them along and then they oil out and become concentrated at a key step... I'm not going to say impossible, and I doubt anyone can since the question is potentially open-ended for any conceivable synthesis approach. That said, the bulk of peanut oil, and the purest and cheapest stuff to use for this purpose, starts non-allergenic before you even begin trying to make or purify the alcohol. It's probably more likely some idiot drops a bag of peanut shells into the oil and they have to strain them out with cheesecloth than the allergens make it through purification. And Cupuaçu has something around six times more arachidic acid than peanut oil, and is "unlikely" to cause peanut allergy. :) Wnt (talk) 19:37, 8 December 2016 (UTC)
- Thank you Jayron that's actually really useful. --TammyMoet (talk) 18:43, 5 December 2016 (UTC)
- And regarding the first question, it's also one of the minor byproducts of the Fisher-Tropsch synthesis of liquid hydrocarbons (especially if the refinery is being run to maximize the production of diesel fuel). It can also be produced by Ziegler-Natta synthesis from ethylene, in which case it can be obtained in high purity. 2601:646:8E01:7E0B:99F8:B355:9D57:7021 (talk) 05:27, 6 December 2016 (UTC)
Fire safety
[edit]If the door's hot it's often said to tell the fire department where you are then seal cracks with wet towels. And breathe near the floor and through a wet towel if need be.
Would floating in a cool bathtub further increase the time before injury or death if the firemen take longer than average? Taking trash bag(s) of good air with you and only opening them to breathe? (exhale inside or outside the bag?) Holding your breath after you run out of air below a certain level of smokiness and hope they get there before you have to breathe again? What's the best breathing strategy? How smoky should the air become before holding your breath as long as you can becomes the best strategy? Sagittarian Milky Way (talk) 19:15, 5 December 2016 (UTC)
- The bathtub? Probably not helpful. Most fire deaths are due to smoke inhalation. Trash bags? An interesting idea. I would favor exhaling into the room. You could try doing an experiment with ten bags (to account for the logistics of moving multiple bags of air around) and reporting how long the air lasted. Original research, of course, but I for one would be interested in the answer. How far could you crawl along a smoky hallway using one or two trashbags of air? If you wanted to prepare ahead of time you might consider getting the clothing and breathing gear that firefighters use. --Guy Macon (talk) 20:06, 5 December 2016 (UTC)
- Definitely exhale INSIDE the trashbag, you only consume a fraction of the oxygen from the air in each breath. Air is about 20% oxygen, exhaled air is about 15% oxygen, you can inhale and exhale a bag of air several times before you deplete ALL the oxygen. Vespine (talk) 21:39, 5 December 2016 (UTC)
- How hard is it to tell how close you are to depletion? The above seems risky, because the user may not realize that they are about to deplete all the oxygen and then start inhaling CO, which does not seem likely to have a good result. Also, we should clearly indicate that Wikipedia and its contributors disclaim any responsibility for the results of the proposed techniques described in this thread. Do not try these techniques at home! --03:17, 6 December 2016 (UTC) — Preceding unsigned comment added by 208.58.213.72 (talk)
- Smoke hood might be a useful article here (although, unfortunately, it doesn't go into much quantitative detail). Tevildo (talk) 22:12, 5 December 2016 (UTC)
- With all the caveats of NOT TRYING THIS AT HOME! I think you would pass out before you die if you keep inhaling and exhaling into a bag, I don't think you could "keep" breathing into the bag until you die. Unless you stuck your head IN the bag which would definitely be a terrible idea. Vespine (talk) 03:43, 6 December 2016 (UTC)
- Smoke hood might be a useful article here (although, unfortunately, it doesn't go into much quantitative detail). Tevildo (talk) 22:12, 5 December 2016 (UTC)
- Plastic garbage bags would melt if anywhere near heat, and catch fire if near flames. However, if you were in an area with smoke but no fire, that might work. I've myself thought if using a scuba tank in a bathtub. Hopefully that would allow you to survive, unless the building collapses (and even then, a bathtub full of water might offer some protection, say if it falls through the floor). StuRat (talk) 03:43, 6 December 2016 (UTC)
- If I recall correctly, the CO2 percentage is the limiting factor, not oxygen depletion. So yes, you can stretch the time by exhaling back into the bag, but you cannot use all the oxygen. WWII-era submarines used a chemical (caustic soda?) to scavenge the CO2 and extend the time in emergencies, I think. Therefore, best practice is (probably) to inhale from the bag and hold the air in your lungs as long as possible with each breath to maximize oxygen extraction, then exhale into the room. Order-of-magnitude guess on time: taking a one-quart breath every 15 seconds, you get one minute per gallon, and a 30-gallon bag gives you half an hour. If you have N bags, after you have used the first bag, exhale the second bag into the first, and eventually you have N-1 bags of once-used air. You are now in trouble, but you can now use the once-used air, producing N-1 bags of twice-used air. If you are not rescued in time, you will lapse into unconsciousness, at some point. -Arch dude (talk) 01:58, 7 December 2016 (UTC)
Ginkgo fruit yield
[edit]How much fruit does a mature Ginkgo biloba produce in one season? Surtsicna (talk) 22:08, 5 December 2016 (UTC)
“ | The seed of G. biloba contains a thin-layer nut, which is consumed as food and a medicine throughout the world. Fresh nuts contain about 41% moisture. Dry nuts contain 6% sucrose, 68% starch, 13% protein and 3% fat [27]. The commercial production of Ginkgo nuts has been reported in China for more than 600 years. About 44 cultivars with best performance in growth have been selected, based on quality, size and shape of their nuts and productivity [2] and [28]. These cultivars are propagated by grafting technique using seedling rootstocks. These grafted plants start bearing nuts after 5 years of age. In China, a widely grown cultivar, Dafushon, in Jiangsu Province, produces 5 to 10 kg of nuts by a 15 year old tree and between 50 to 100 kg by a 50 year old tree. One recent production from 700,000 to 800,000 trees produced an average of 6000–7000 tons of dry nuts per year [2]. | ” |
- Emphasis mine, from here [8]. That article doesn't clarify if that's a fresh or dry weight, but the cited source probably does. In my experience dry weight is what is usually reported in scientific contexts. Note also that wild types and cultivars not designed specifically for seed production will probably make less seeds, and they can take 20-30 years to mature, a fact stated earlier in the same article. SemanticMantis (talk) 22:19, 5 December 2016 (UTC)
- Within 10 minutes! I had been searching for an hour. Thank you! Surtsicna (talk) 22:37, 5 December 2016 (UTC)
- You're welcome! There are probably other estimates out there, this should be good enough for most casual usage. (It did take me several searches on Google Scholar. I think it was /Gingkgo seed production/ that worked, but part of it was being familiar enough with the literature to know that at least some estimate would certainly be there :) SemanticMantis (talk) 22:43, 5 December 2016 (UTC)
- Within 10 minutes! I had been searching for an hour. Thank you! Surtsicna (talk) 22:37, 5 December 2016 (UTC)
- I am tempted to say "too much" but as a New Yorker, I would compare the yield to a non-cultivated Krabapple or cherry. No one would grow the plant for human consumption. μηδείς (talk) 04:19, 6 December 2016 (UTC)
@ Medeis, You are wrong, Read the article.Richard Avery (talk) 07:52, 6 December 2016 (UTC)
Non-Gingko meta discussion
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- @ Medais, with the greatest respect for your wide and detailed knowledge I feel duty bound to graciously inform you that when you assert that "No one would grow the plant for human consumption" you are I fear somewhat mistaken. This error on your part is, possibly due to the fact that you seem not to have read the relevant article, to wit, Ginkgo biloba where it indicates that this tree is cultivated and harvested for it's slightly toxic nut widely in the Far East. Richard Avery (talk) 15:12, 6 December 2016 (UTC)
- Perfect response to the hatted argument. Stated in the finest traditions of diplomacy. Debate in Parliament would benefit greatly from such an approach. Baseball Bugs, even you should now be satisfied! Eliyohub (talk) 13:28, 7 December 2016 (UTC)
- Our article does not clearly state an essential fact, which is that the "fruit" of the gingko smells quite literally like dogshit. As a result most Americans don't like to have female gingko trees near their houses. Also the "nuts" are not valued enough here to make the trees worth cultivating. But they are highly valued in China, and the trees are extensively cultivated there. (FYI, an "@" has no effect if you don't spell an editor's name correctly.) Looie496 (talk) 15:15, 6 December 2016 (UTC)
- Our article Ginkgo biloba does state that "smells like rancid butter or vomit", due to the butyric acid, which is the same reason Hershey's "chocolate" tastes/smells of vomit to some people. Perhaps there is someone out there who associates Gingko nuts with chocolate... My WP:OR is that the odor is only strong on the fresh pods, and the dried nuts are fine. SemanticMantis (talk) 18:53, 6 December 2016 (UTC)
- AFAICT, those skilled in Cantonese cuisine can cook anything and make it taste good. Wnt (talk) 19:08, 6 December 2016 (UTC)
- I'll happily admit defeat, as even dogs will eat their own feces. See http://ddot.dc.gov/page/female-ginkgo-tree-removal-policy μηδείς (talk) 04:22, 8 December 2016 (UTC)
- AFAICT, those skilled in Cantonese cuisine can cook anything and make it taste good. Wnt (talk) 19:08, 6 December 2016 (UTC)
- Our article Ginkgo biloba does state that "smells like rancid butter or vomit", due to the butyric acid, which is the same reason Hershey's "chocolate" tastes/smells of vomit to some people. Perhaps there is someone out there who associates Gingko nuts with chocolate... My WP:OR is that the odor is only strong on the fresh pods, and the dried nuts are fine. SemanticMantis (talk) 18:53, 6 December 2016 (UTC)
- @ Medais, with the greatest respect for your wide and detailed knowledge I feel duty bound to graciously inform you that when you assert that "No one would grow the plant for human consumption" you are I fear somewhat mistaken. This error on your part is, possibly due to the fact that you seem not to have read the relevant article, to wit, Ginkgo biloba where it indicates that this tree is cultivated and harvested for it's slightly toxic nut widely in the Far East. Richard Avery (talk) 15:12, 6 December 2016 (UTC)