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May 11

Hatchlings of olive ridley turtles

When they come out, within one second they know they have to move towards the sea. https://www.youtube.com/watch?v=Ipf0fehg5os

How do they decide with one second age that they should move towards the sea, not towards the land? — Preceding unsigned comment added by Lordracktry (talk • contribs) 04:55, 11 May 2020 (UTC)

They look for light on the water, usually brighter than looking inland. In the Threats sub-section of our article Olive ridley sea turtle it tells us "...coastal development also threatens newly hatched turtles through the effects of light pollution. Hatchlings which use light cues to orient themselves to the sea are now misled into moving towards land, and die from dehydration or exhaustion, or are killed on roads." HiLo48 (talk) 05:50, 11 May 2020 (UTC)

They don't decide; it's instinct.--Shantavira|^{feed me} 09:39, 11 May 2020 (UTC)

Sulfuric acid

The infobox at sulfuric acid conforms what I saw elsewhere: its melting point is about 10 °C or 50 °F. Question: how do car batteries manage to work in cold weather? I somehow thought the acid/water mix had a much lower freezing point than plain water. What's the deal? Thanks. 2602:24A:DE47:B270:DDD2:63E0:FE3B:596C (talk) 08:04, 11 May 2020 (UTC)

Freezing-point depression of the acid/water solution sounds right. Sulfuric acid#Europa has a useful datapoint. DMacks (talk) 08:46, 11 May 2020 (UTC)

The sulfuric acid concentration in car batteries is about 37%, which is to say that it is still mostly water. The freezing point of that solution will depend on the relative concentration of two liquids, calculating the freezing point of a mixture of two liquids is fiendishly difficult, but it will be generally lower than the freezing point of either one in isolation. --Jayron32 13:34, 11 May 2020 (UTC)

Re: "Calculating the freezing point of a mixture of 2 liquids is fiendishly difficult." Well what if you had a diagram of freezing point of percentage, for example, the middle point being 50/50 water/H2SO4, from 0 to 100. What would the curve look like, linear? Asymptoptic? 67.175.224.138 (talk) 18:54, 11 May 2020 (UTC).

Calculating the values is fiendishly difficult. Where do you get such a diagram from? Diagrams are not handed down from God to be used whenever someone needs them. Someone has to make such a diagram somehow. Freezing point behavior for sulfuric acid solutions have been experimentally determined, see here, and as you can see the behavior is relatively well behaved up to about a 40 percent solution, and after that the behavior begins to behave rather chaotically depending on the exact measurement conditions and theoretical assumptions. Remember, diagrams you may use still need to be created by someone, and in this case the behavior of sulfuric acid solutions is complex and messy and if you observe the diagram there, you can see that (from the solid line) does not indicate a nice relationship between concentration and freezing point. --Jayron32 19:21, 11 May 2020 (UTC)

Okay, clearly the curve is not linear, or asymptotic. Are there any solutions by concentration, where the curve is? 67.175.224.138 (talk) 22:10, 11 May 2020 (UTC).

[1] page 7 also has a nice unified graph, cited to doi:10.1021/ja01160a005 that has several different graph sections. DMacks (talk) 04:47, 12 May 2020 (UTC)

Thanks everyone. It looks like at 40% concentration (as found in car batteries) the freezing point gets as low as –60 °C. Maybe that concentration was chosen to make the freezing point as low as possible. 2602:24A:DE47:B270:DDD2:63E0:FE3B:596C (talk) 21:57, 11 May 2020 (UTC)

May 12

Is body odor Nature's way to enforce social distancing?

Body odor is influenced by sweat, so the body has some control over what bacteria will grow on the skin. Also, the brain can flag smells in any way that it sees fit. So, if we find body odor in general unpleasant, is this then caused by the advantage of keeping some distance to each other? Count Iblis (talk) 05:53, 12 May 2020 (UTC)

We do have an article on Body odor, but it doesn't seem to address social distancing. Well worth a read though. HiLo48 (talk) 07:57, 12 May 2020 (UTC)

Yes. The body also emits odors that can't be smelled, such as pheromones. 67.175.224.138 (talk) 10:41, 12 May 2020 (UTC).

Pheromones tend to lead to the opposite of social distancing. HiLo48 (talk) 11:13, 12 May 2020 (UTC)

Oooo HiLo48, you brute. Martinevans123 (talk) 11:17, 12 May 2020 (UTC)

People were not particularly bothered by body odor until marketing told them to be. Disgust can be socially conditioned (i.e. a learned behavior rather than a programmed one), and there's nothing natural about being repulsed by body odor (in the sense of "it is the proper order of things"). For thousands of years people were unbothered by body odor until marketing in the early 20th century convinced people they should be. [2]. There's little evidence that the natural scent of otherwise clean humans is inherently repulsive. --Jayron32 12:31, 12 May 2020 (UTC)

On a similar line, this research on the use of deodorant by those with naturally low body odour (a non functional ABCC11 variants) may be of interest [3]/[4] [5] [6] [7]. Also before anyone says it, note that while it's true that this non functional ABCC11 variant seems to result in changes which result in lower body odour, this doesn't mean that this mutation was favoured for that reason and especially not for the preference of other humans, as it appears to have a number of effects. We really have no idea what, if any, evolutionary advantage resulted from the variant. And I say "if any" especially since the variant is hypothesised to have arisen in cold environments and also results in fewer sweat glands. It could easily have been simply genetic drift due to a lack of an evolutionary disadvantage. (There is some general research into the variant e.g. [8] [9] which I haven't really looked at.) Of course such findings are also then seen as a potential money maker in another direction, namely making recommendations on such matters in a personalised pharmacogenetics type approach [10]/[11]. Nil Einne (talk) 08:19, 13 May 2020 (UTC)

Manly sweat makes other men more cooperative.  --Lambiam 19:39, 12 May 2020 (UTC)

False color images in astronomy

When most people think of the sun, the image that often comes to mind is this to the point where sci-fi movies often depict it that way and a lot of users have insisted that the aforementioned image stay at the top of the infobox in the article Sun. Of course, that image is actually false-color while the sun is actually white yellow and another image is a much more accurate depiction of how it appears in real life to human eyes. Are all the colorful images of nebulae and other galaxies, many of them quite iconic, such as the ones in here also false-color? If not, are there obvious indications in ones that actually are false-color? StellarHalo (talk) 19:55, 12 May 2020 (UTC)

Majority of colorful images are in false color. Real color images of galaxies and nebular are rather bland. Ruslik_Zero 20:32, 12 May 2020 (UTC)

That said, some astronomical photographs use filters to isolate particular narrow portions of an object's full spectrum corresponding to the output of particular elements. These can be informative about the processes going on in the objects: for example, Hydrogen-alpha filters are useful for observing the Sun, which is bright enough to give a good optical or photographic image using only the light of this spectral line. They might also or instead make a faint object or feature stand out more clearly: many amateur telescope users employ a Nebular filter to increase the contrast and hence visibility of faint Nebulae, and various colour filters to enhance markings on/in planetary surfaces or atmospheres.

While most astronomical false-colour images do not represent what the human eye, if closer to the object, might theoretically see, they are genuinely derived from the object's actual light and thus give useful information. They are not just arbitrary choices to make it "look prettier", although that might be a fortunate by-product. {The poster formerly known as 87.81.230.195} 90.197.24.23 (talk) 00:51, 13 May 2020 (UTC)

The well-known Pillars of Creation image often seen on posters^[12] or T-shirts^[13] is a good example. Its colours were constructed by combining many images taken with three different narrow-band filters and combining the three monochromatic signals by interpreting them "falsely" as an RGB signal. More detail is given in an article on the National Geographic website: Photographing the Pillars of Creation. A dead give-away of the image colour being false is the brightly pink colour of the stars. In true colour, the image would not nearly be as captivating. Someone's perspective of the universe can, allegedly, be ruined by that realization,^[14]  --Lambiam 07:55, 13 May 2020 (UTC)

May 13

Oxygen masks on planes

There's understandable concern these days[15][16] about flying on planes potentially breathing corona-infected aerosols exhaled by other passengers. On the other hand, every (US) airline seat already has an oxygen mask that can drop down in front of the passenger, and they instruct you before every flight how to use the mask.

Is there some reason they can't just start deploying those masks every flight and let the passengers wear them through the whole flight? Where does the air come from for those masks anyway? Is it actually pure oxygen, carried on board in tanks, or is it normal air brought in from outside the plane, heated, and pressurized? The latter makes more sense in terms of takeoff weight, I'd think, and hopefully it could run for as long as desired at maybe some slight cost in fuel efficiency. Thanks. 2601:648:8202:96B0:3567:50D5:8BFF:4588 (talk) 07:43, 13 May 2020 (UTC)

Emergency oxygen system is the article you want to read. --Wrongfilter (talk) 07:48, 13 May 2020 (UTC)

If you're on a plane and the masks drop down, the possibility of catching someone else's infections is the least of your worries. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:49, 13 May 2020 (UTC)

After cabin decompression, supplying air rather than oxygen would be impractical. A mask would have to handle a large ininternal positive pressure, and even if robust and fixed firmly enough to handle it, the pressure difference would make exhaling very difficult. -- Q Chris (talk) 11:07, 13 May 2020 (UTC)

Given that most Emergency Oxygen Systems uses chemical oxygen generators (aka oxygen candles), such a solution would a) create a fire hazard, b) lead to a not insignificant amount of extra maintenance as the candles would have to be replaced between each flight, c) at a significant cost to the airlines, and d) probably not deliver enough oxygen for long distance flights (an EOS is required to deliver oxygen for "minimum 10 minutes" and considering cost and weight most are likely not designed for much more than that)... At least to my mind it would be simpler, cheaper, better, and safer to simply require all passengers to use masks, as IATA is currently recommending. WegianWarrior (talk) 11:57, 13 May 2020 (UTC)

Yes, to review, the passengers' oxygen systems are just to keep the meatbags alive until the pilots can descend. The pilots have bottled oxygen, I believe, at least on large commercial aircraft, but carrying enough for every passenger for a long period of time would be impractical and a major fire hazard. If depressurization happens at high altitude, the pilots declare an emergency and immediately descend. Air traffic control's job then is to get everything else out of their way. --47.146.63.87 (talk) 19:37, 13 May 2020 (UTC)

I do believe the polite term is "self loading cargo" instead of meatbags :) WegianWarrior (talk) 19:51, 13 May 2020 (UTC)

As to "declare an emergency and immediately descend", I was reminded of this anecdote posted 30 years ago on Usenet by one of the pilots involved:

Part 1 Part 2 (ending with a repeat of Part 1). --76.71.5.208 (talk) 21:51, 13 May 2020 (UTC)

Astonishing anecdote. It is an excellent reminder of the seriousness of altitude hypoxia - especially in its ability to distort perception, and particularly how hypoxia can degrade the pilot's ability to take simple precautionary actions, ask for help, and even to understand what is occurring.

One of the most useful trainings is FAA CAMI's hypoxia altitude chamber, in which airmen may physically experience the extraordinary physiological and psychological symptoms that simulate a high-altitude depressurization or oxygen-system-failure emergency. The human brain operates differently when deprived of oxygen; and because the human requires its brain to conduct the vital task of perception, it is usually not obvious to the person experiencing hypoxia that they are rapidly entering a very serious emergency condition.

On the reference desk, I have previously linked to the famous Four of Spades video, which was also shown during our FAA altitude training classroom session. A key thing to remember is that the airman in that video is a physically-fit, highly-intelligent pilot officer of the United States Air Force; when his brain is deprived of oxygen, the results are nearly incomprehensible: "no symptoms yet."

Nimur (talk) 19:24, 14 May 2020 (UTC)

At high altitude, the regular cabin air is air brought in from outside and pressurized: bleed air. This can't be relied on in a depressurization event because there could be engine failure or structural damage to the craft, and anyway you would need a piping system installed to deliver the air to each seat, which would be complex, heavy, and itself susceptible to failures. Also, unless the oxygen masks are airtight and have a one-way exhalation valve, they still won't protect fully against virus transmission, though they may reduce risk. --47.146.63.87 (talk) 19:37, 13 May 2020 (UTC)

May 14

How many SARS 2 "organisms" are in someone when they die? What is their mass and density?

Sagittarian Milky Way (talk) 01:23, 14 May 2020 (UTC)

Think the question should be worded how many Covid organisms are enough to make a person sick, and how many are enough to kill a person. 67.175.224.138 (talk) 02:28, 14 May 2020 (UTC).

The number of individual organisms in a body overpowered by 'SARS 2 organisms' or required to kill an individual will vary with the individual. A person with an ongoing illness - say of the heart or liver or diabetes - will require less organisms to overpower them. Similarly an older person of 50 kilos (110lbs) would probably require less organisms than a younger person of 120 kilos (265lbs). One then has to take into account gender, race or age for example. Based on these variables the answer is going to vary. All this is apart from what method would be used to measure the mass and density of pathogens present in a body.Richard Avery (talk) 12:58, 14 May 2020 (UTC)

• We can do a Fermi estimate by looking at the fact that there is about 60 grams of DNA in your body right now, and viruses are mostly DNA with a protein coating. There are about 3,000,000,000 base pairs in each strand of DNA and Covid 19 has about about 30,000 base pairs, which is about 10^-5 the amount of DNA in your body, so IF every single cell in your body was infected, the DNA from the coronavirus should weigh about 0.00060 grams. DNA base pairs have a mass of about 650 daltons, and the current coronavirus has a mass on the order of [https://www.cusabio.com/2019-novel-coronavirus.html 5,500,000 daltons), meaning that DNA is about 1/10,000 the mass of the virus. That means that IF every single cell in your body was infected with it, the total mass of all of the coronavirus particles would weight about 60 grams, or 0.1% of your weight. That would be an upper limit, and since MUCH less than "every cell in your body" would be infected, you can expect the actual percent of mass to be several orders of magnitude less. --Jayron32 13:41, 14 May 2020 (UTC)

What are the biggest living organisms that are without a nervous system?

What are the current biggest living organisms that are without a nervous system? --ThePupil (talk) 10:36, 14 May 2020 (UTC)

You need to say what you mean by "creature". Bazza (talk) 10:57, 14 May 2020 (UTC)

Right. I changed the term. Thank you.--ThePupil (talk) 11:19, 14 May 2020 (UTC)

As is often the case, Wikipedia has an article which should answer your question. Looks like it's a tree. Bazza (talk) 11:34, 14 May 2020 (UTC)

Oh! By organisms, I mean organisms which do not belong to the plants, but something with movement. I'm not sure what is the right term for it. --ThePupil (talk) 12:10, 14 May 2020 (UTC)

Well, the same article should tell you what you want to know. Bazza (talk) 13:15, 14 May 2020 (UTC)

Plants have movement, by the way. Movement is often one of the defining characteristics of "life" --OuroborosCobra (talk) 13:36, 14 May 2020 (UTC)

They just move very slowly, compared with animals. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:43, 14 May 2020 (UTC)

Not all of them. And animals are comatose compared to some fungi. Bazza (talk) 14:25, 14 May 2020 (UTC)

Thank you. Except for plants, are there other living from the animalia kingdom who doesn't have nervous system? --93.126.116.89 (talk) 14:57, 14 May 2020 (UTC)

A candidate for the biggest animal without a nervous system is this sponge, said to be the size of a small minivan. Mikenorton (talk) 15:19, 14 May 2020 (UTC)

(EC) I don't entirely understand your question as plants are not in the animalia kingdom. And fungi, that are mentioned above, are neither plants or animals and also lack a nervous system. (While classification of eukaryotes, as with any diverse group, is difficult, and some place animals and fungi in the same group e.g. Opisthokont, animals and fungi are still different groups within those groups AFAIK.) But if your looking for animals without a nervous system I suggest you read that article and Evolution of nervous systems. Sponges (possibly a monophyletic grouping) are generally regarded as having no nervous system. Nil Einne (talk) 15:32, 14 May 2020 (UTC)

And you then come up against the question of whether a massive sponge is one organism or a large colony. --Khajidha (talk) 01:12, 15 May 2020 (UTC)

Also, what do you mean by nervous system? Jellyfish have a diffuse neural net. Does that count?--Khajidha (talk) 01:14, 15 May 2020 (UTC)

Basically I searched for any kind of information about any kind of organism (that isn't plant or fungus) that doesn't have a nervous system. By nervous system, I mean to any kind of innervation. If I'm not mistaken, I've heard in past that there are some worms or nematode which don't have a nervous system, but I'm not sure if I understood it well.--ThePupil (talk) 18:20, 15 May 2020 (UTC)

All sources seem to agree that the only animals completely lacking a nervous system are the sponges. On the other hand there ist this roundworm that doesn't uses neurons to feed: its pharynx contracts rythmically and ingests the bacteria the worm feeds on without need for neural input. But there are three neural circuits that stop the feeding and cause the worm to spit if it risks to ingests someting harmful, see [[17]] 2003:F5:6F08:8200:351A:656A:496C:6A58 (talk) 13:52, 17 May 2020 (UTC) Marco PB

You're choices are rather limited. Count Iblis (talk) 19:29, 17 May 2020 (UTC)

Immortality Research

I was curious if there scientific institutions or organizations which seek to develop methods to allow people to either live very long or achieve some form of immortality. I have heard about the cryogenic research which is conducted in some countries, but cryogenics are not life-prolonging in themselves, at least not as far as I know. The idea seems to be that if a corpse is frozen, that it could be brought back to life in the far future.--2A02:1205:5049:A1D0:C837:56F9:23F:C686 (talk) 19:01, 14 May 2020 (UTC)

You could start by reviewing Ageing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:10, 14 May 2020 (UTC)

Also, the articles Indefinite lifespan and Strategies for Engineered Negligible Senescence might be of interest to you. You can also take a look at the Aubrey de Grey article. Futurist110 (talk) 23:03, 14 May 2020 (UTC)

Young blood transfusion if you are into vampire chic. 2601:648:8202:96B0:3567:50D5:8BFF:4588 (talk) 07:18, 16 May 2020 (UTC)

Can a person who had coronary artery disease and a heart attack in their early 50s (and survived) live into their 80s and beyond?

Can a person who had coronary artery disease and a heart attack in their early 50s as a result of having their arteries be clogged with plaque (and survived this heart attack as a result of going to the hospital and getting their arteries unclogged in time) live into their 80s and beyond? If so, just how likely is this to occur? It this very unlikely to occur? Or are the odds of this occurring more likely than one thinks? Futurist110 (talk) 23:02, 14 May 2020 (UTC)

I know someone who had a heart attack before 40 and is now 73, so maybe you could ask again in seven years? —Tamfang (talk) 00:54, 15 May 2020 (UTC)

The answer is yes, this is perfectly possible, if the person maintains an solid exercise regime and a healthy well balanced diet. It is not only possible but has happened on multiple occasions, too numerous to name. 86.186.232.80 (talk) 10:05, 15 May 2020 (UTC)

Without even looking, I can almost certainly say that a person has had that happen at some point in the 10,000 years of humanity, given the tens of billions of people who have lived and the wide variation in their stories. It could even be more than one, so one could even use the word "people" in that place and be truthful. --Jayron32 14:26, 15 May 2020 (UTC)

So, just to make the point, here's one person who survived 43 years (at the time of writing) after his first heart attack. Here is someone who has survived, so far, 42 years after his first heart attack, and he's had several since then. He's still alive today. Here is someone who doesn't quite make your criteria, but he's close. He had his first heart attack at 52, and was 78 at the time of writing the article. Based on those, we can definitely say that it is more than a person who has done as you have described. It is definitely people who have done so. --Jayron32 14:32, 15 May 2020 (UTC)

It is possible, of course, but unlikely as ischemic heart disease is a progressive disease. Ruslik_Zero 21:01, 15 May 2020 (UTC)

• This article works out a probability model for your question and using the given equation, or eyeballed-numbers from Figure 1F, one can work out the odds of the person dying at any particular age (keep in mind the obvious caveats of extrapolating the model to non-US population, and applying it to any individual patient). Abecedare (talk) 22:34, 15 May 2020 (UTC)

See here. Count Iblis (talk) 18:42, 16 May 2020 (UTC)

May 15

RF constant transmission

I have a TV antenna in my attic. I moved it and lost all but 2 channels. I moved it back to where it was and got all the local channels back. I then noticed that when I stand where the antenna didn't work, my cell phone loses almost all reception. I also don't pick up my wifi. I experimented and found that the "dead zone" is a line from one side of the attic to the other. I went outside and climbed up a ladder and found the line extended outside the house. I though it might be a signal flooding everything, so I got a small radio to see if I could hear anything. Without turning it on, the two speakers began chirping and clicking at high speed. Now, I'm wondering, what RF signal in rural South Carolina travels in a tight beam with enough energy to excite speakers in a radio that isn't turned on and, as a result, blocks television and cell phone reception? The only hint I have is that there is a fire station in the general direction of the line in one direction - nothing but farm land in the other direction for miles. Past the fire station, a good 20 miles away, is an airport. 97.82.165.112 (talk) 12:12, 15 May 2020 (UTC)

A simple experiment is to turn off the main breaker for your home to see if the phenomenon stops. That would pretty much tell you if it's coming from inside your home or not (although a few possible sources have battery backups). 13:04, 15 May 2020‎ Jc3s5h

Another possibility is that it is some kind of local "node" for some signal much farther away. Wave phenomena like radio can have strange behaviors where a signal can have localized areas of high and low signal strength due to the oddities of harmonics and wave interference. You can find this with sounds too; especially in rooms with complex shapes you will occasionally find locations in the room where there are sound "dead spots" and other locations with strange audio phenomena like unusually loud sounds and weird flanging effects and things like that. I suspect that radio signals can produce such spots as well, and perhaps you just happen to have one in your attic.--Jayron32 14:23, 15 May 2020 (UTC)

This sounds like it is electromagnetic interference. Perhaps it is coming from a wire in your house. Some power supplies, and electric motors can put out a strong unwanted signal in radio waves that interfere with reception. Even fluorescent lights put out a weak broadband interference. Electronic devices are often more narrow band emitters, just interfering with some radio stations but not others. Graeme Bartlett (talk) 23:34, 15 May 2020 (UTC)

Indeed, I believe that's what Jc3s5h's suggestion was about testing for. --76.71.5.208 (talk) 01:18, 16 May 2020 (UTC)

I think I found it. Cutting all power in my house didn't help. I can't check TV, but my phone gets almost no signal and my radio keeps ticking, even if it isn't turned on at all. It is a very narrow dead zone, about 5 feet wide. When my radio is on, I still hear tick sounds, but I can tune into a station. It gets much louder if I move out of the dead zone. Using an antenna on a long stick and my radio, I traced the line of the dead zone to the back of my property to the front, about 500 yards. That gave me a very good line. I followed the line on the map and marked locations where it crossed a road. I followed that and I found that the line crosses a large antenna tower, marked as private property for the airport. There is a wide flat thing sticking out one side. If I get my antenna up near it, I can hear the same clicking on my radio. Going to the other side of the antenns structure, I get no interference. Tracing the line the opposite direction on the map, it crosses the airport. So, I googled pictures and it appears this is one of the outer-middle-inner towers. I'm not sure what they do, other than create a narrow line where I can't pick up radio signals very well. I'm not overly concerned, just curious. I moved my TV antenna far away from the dead line and I am getting far more broadcast channels than I ever got before. 97.82.165.112 (talk) 14:37, 16 May 2020 (UTC)

Do any of the signal audios in the Marker beacon article match the pattern of the clicks? Also, if you draw a line on a map from your house to that marker beacon, does it cross the approach line to the runway at a right angle? The distance between the close end of the runway and the beacon should be about 1.85 km for the outer, and roughly 1 km for the middle marker.  --Lambiam 17:36, 16 May 2020 (UTC)

The clicks sound random to me. I checked the map. In my mind, it is many miles between the tower and the airport because there is no direct road and it takes a good 30 minutes to drive between them. But, according to Google Maps, they are about five miles apart, if I'm reading it right. You can check. GSP is an easy airport to find on Google Maps. Southeast, you will find Sugar Tit. I live very close to that. The tower is next to the power company at 417 and Bens Creek Rd. On the map, it is just a field, so it must have been built between the map photo and now. 97.82.165.112 (talk) 12:15, 17 May 2020 (UTC)

Hmm. So the tower is really quite far from the approach flight path, which would pass over the Walmart on Woodruff Road. But a line perpendicular to the approach flight path going through the Laurens Electric site does cross that path at about 1.5 to 2 km from the end of the runway, which is consistent with an outer marker. Wikipedia states that Sugar Tit is located around the junction of State 101 and State 296. The position on the perpendicular line closest to that junction is near to 34°49'52"N 82°09'50"W. The line crosses Brockman Rd near what (at least according to Google Maps) is 760 Brockman Rd.  --Lambiam 11:09, 18 May 2020 (UTC)

I went to the power company and asked about it. No secret. It is a direct-line radio communication line to the BMW factory. They kept cranking up the power because they were getting interference. I explained that the interference was probaby my attic because my house is on the highest hill in the area and my attic is well above the tree tops. The guy I was talking to didn't think one house could cause that much interference, but he said the people who isntalled it said it was well above everything in the area, so they will look into it and see about moving it so they can communicate without the interference. One mystery solved. 97.82.165.112 (talk) 19:24, 18 May 2020 (UTC)

May 16

Why does viral load matter?

If viruses reproduce exponentially, one might naively expect a low viral load to simply cause a slight delay in the onset of an illness. Even one virus turns into a large number in a short amount of time. So how is it possible that any viral infection could have a severity that depends on whether you start off with one virus particle or 100,000 virus particles, given that one in theory should quickly turn into 100,000? 2600:8806:3400:3DB:4970:60BC:F1C1:34BF (talk) 15:30, 16 May 2020 (UTC)Nightvid

Whereas if you started with 100,000 particles, you'd shortly end up with 10,000,000,000 particles. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:22, 16 May 2020 (UTC)

If your farmlands get infested with breeding rabbit couples, does it matter whether it is one pair or 100,000 pairs? In the first case you might be able to control the situation by hiring an exterminator specializing in rabbits. In the second case, even if you employ all terminators from the whole State, the problem will overwhelm them.  --Lambiam 17:46, 16 May 2020 (UTC)

We have an article on viral load, but unfortunately do not have one on initial viral load which is what I assume you are asking about, most likely with respect to COVID-19. I believe the answer is that it takes some time after initial antigen exposure for your immune response to ramp up, and a higher initial viral load gives the virus a head start.

So if you are infected with a very low initial vital load, your immune response may be in full swing before the viral load is sufficiently high to cause illness, resulting in an asymptomatic case. But with a high initial viral load, not only will the threshold have been exceeded for even longer before the effective immune response, but the viral load will be even higher when it does takes hold, leading to a sever illness.

I'm sure that explanation is over simplified, but hopefully not to the point of being useless. I didn't find any references of the mechanism from a cursory search, but I'll keep looking. -- ToE 01:15, 17 May 2020 (UTC)

Here something, not much, about Minimal_infective_dose. Some more relevant points: after infection and before replication begins the virus must find some susceptible cells, enter them and start replication. This can take hours or even days, during which time the virus is vulnerable. Replication time is also not zero: it varies from a minimum of 13 minutes for some fagi to 1.2 days for HIV and at least 30 hours for one hepatitis B virus. All together this means that at some low viral load immune response can have time enough to whipe out all attackers before they become dangerous, just as ToE said. A figure one meets often is 100 000 as a minimal infective dose 2003:F5:6F08:8200:351A:656A:496C:6A58 (talk) 12:47, 17 May 2020 (UTC) Marco PB

May 17

neutrino speeds and the speed of hypothetical axion

I think I understand the that the reason for neutrinos going so near lightspeed is that they are created in somewhat energetic nuclear reactions while also being very low mass, and then not slwing down by being neutral in charge. But axions are theorized to be cold dark matter, so they are slowExactly why sre they slow? And they are slow relative to the galaxy they orbit?Rich (talk) 00:16, 17 May 2020 (UTC)

It has to do with the creation mechanisms for these particles in the early universe. Neutrinos decoupled from a state of thermal equilibrium and cooled only through the expansion of the Universe. Due to their small mass they had velocities (more precisely, velocity dispersion) close to the speed of light at the time relevant for structure formation, i.e. they were "hot". I don't understand the details for axions, but I refer to the articles Axion#Cosmological_implications and Misalignment mechanism, which indicate that an interaction robbed axions of their kinetic energy making them "cold" early on. --Wrongfilter (talk) 12:10, 17 May 2020 (UTC)

I gather you're getting at hot dark matter versus cold dark matter models. Noting this for other readers; there are also warm dark matter models. --47.146.63.87 (talk) 20:17, 17 May 2020 (UTC)

I'm not contradicting anything you stated, just filling in details: neutrinos have an incredibly tiny mass, long thought to be zero, so it doesn't take much to get them to high velocities, and they only interact through gravity and the weak interaction so they're basically unimpeded by "ordinary matter" or photons and hence there's nothing to slow them down. A fascinating thing is that in contrast, neutrons, though they have no net electric charge, do interact electromagnetically and have a magnetic moment, which I think means they still can scatter off charged particles and lose energy that way. Someone please correct me if I'm wrong. --47.146.63.87 (talk) 20:17, 17 May 2020 (UTC)

They probably can, but there are no free neutrons (a free neutrons decays after 8 or 9 minutes). Axions (presumably, if they exist, blabla) have much smaller masses than neutrinos, which is probably what prompted the question in the first place. --Wrongfilter (talk) 20:50, 17 May 2020 (UTC)

vaccine research

Our President is on TV saying he expects a covid-19 vaccine by the end of the year, and at least some people seem to take this seriously. Some vaccines like Ebola have in fact been developed pretty fast. Some older ones like polio may have taken longer, but they didn't have modern biotech then. But, there is no HIV vaccine even today, other than pre-exposure prophylaxis that has to be taken frequently.

Is there some reason to expect covid-19 vaccines to be easier to develop than HIV vaccines? I think I've heard HIV might be unusually difficult, but I don't know specifics. Thanks. 2601:648:8202:96B0:3567:50D5:8BFF:4588 (talk) 01:24, 17 May 2020 (UTC)

"OUR President"? This is a global encyclopaedia. My country doesn't have a President. Anyway, I suspect there is a bigger effort being put into finding a vaccine this time around than has ever happened before. And despite the repeated hate talk about the country, Chinese authorities made public the details of its genome from their own research quite early in the piece.That increases the odds considerably. HiLo48 (talk) 01:38, 17 May 2020 (UTC)

If you ask him I'm sure he'd attest to being everybody's president ;). More seriously I'd expect the HIV genome is sequenced also. It's been around for decades so I'm wondering what's different. 2601:648:8202:96B0:3567:50D5:8BFF:4588 (talk) 01:43, 17 May 2020 (UTC)

I'm sure the original poster meant his or her own country's president, and just forgot to mention which country. No big deal. --76.71.5.208 (talk) 05:02, 17 May 2020 (UTC)

Sadly, English lacks a clusivity marker that some other languages have, which would have reduced the confusion that led to HiLo48's expressions of offense to being included in the "we" which the OP did not intend to do. --Jayron32 13:16, 18 May 2020 (UTC)

It's possible Trump wants the public to think he'll have a vaccine soon by year's end, in order to get more votes. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:45, 17 May 2020 (UTC)

By Novemeber it will be pretty clear how vaccines are coming, and also how well the human sacrifice reopening plan has worked out. Trump most of all seems to want the virus to just go away so we can get back to whatever. So he tends to be optimistic about anything that might make that happen. We'll see if the current thing works. The last few didn't, but I suppose it's important to keep trying. 2601:648:8202:96B0:3567:50D5:8BFF:4588 (talk) 05:09, 17 May 2020 (UTC)

See COVID-19 vaccine and HIV vaccine#Difficulties in development. Most humans can beat the COVID-19 virus on their own and build immunity (unknown for how long). A vaccine may only have to trigger this existing defense system. The COVID-19 pandemic causes many resources to be used, and some projects to bypass normal safety standards. COVID-19 vaccine currently says "By May, 159 vaccine candidates were in development". Some are bypassing animal trials, and it's considered to deliberately expose volunteers to the virus to measure vaccine efficiency faster. PrimeHunter (talk) 02:26, 17 May 2020 (UTC)

A news story I watched earlier tonight referred to the process "deliberately expos[ing] volunteers to the virus to measure vaccine efficiency" as human challenge trials. I think Wikipedia should have an article on that, or if there is an appropriate existing article, that phrase should redirect to it. --76.71.5.208 (talk) 05:02, 17 May 2020 (UTC)

We have variolation which is sort of related. 2601:648:8202:96B0:3567:50D5:8BFF:4588 (talk) 05:11, 17 May 2020 (UTC)

Though variolation involves intentional infection (with a low initial viral load -- see 2 questions above) in order to generate immunity, these proposed human challenge trials would involve intentional infection in order to test for immunity. -- ToE 15:11, 17 May 2020 (UTC)

We have the section COVID-19 vaccine#Controversy of proposed "challenge" studies, though it's not really an appropriate target for a redirect from your red link. A more general article on the history and ethics of challenge studies in general would be welcome. -- ToE 15:11, 17 May 2020 (UTC)

Small consolation to the 85,000+ Americans who weren't able to beat it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:54, 17 May 2020 (UTC)

As seen in the articles that PH linked to, there are specific challenges to HIV vaccine development that should not be ascribed, without reasonable basis, to any other vaccine development. HIV is unique in a number of ways that make it challenging to develop a vaccine. Among these is that classical vaccine development often intentionally mimics the ways the body develops natural immunity to an infection, but HIV has less than a handful of case where human immune responses actually beat it and developed immunity. That's not true of COVID19. HIV antigens also don't seem to be stable in non-live virus, which makes it hard to use killed virus as a vaccine. HIV has a high mutation rate, and specifically, a high rate of mutation to allow it not only to evade the immune system, but to attack and kill the immune system. Its infection target is the very system that a vaccine uses to provide immunity, the immune system. COVID19 certainly has a wide range if effects, but its main target is the lungs, not the immune system. Honestly, HIV is fairly unique in its difficulty to develop a vaccine, almost everything else out there is much, much easier to develop vaccines against. --OuroborosCobra (talk) 20:53, 17 May 2020 (UTC)

Ok but for example don’t flu vaccines not always work that well for the year they’re designed for, and don’t they take quite a while to make? And common cold vaccine has been a big challenge too. So i’m not sure optimism is called for.Rich (talk) 06:04, 18 May 2020 (UTC)

Influenza vaccines don't always work that well for the year (actually influenza season) they're designed for mostly because they're based on predicting months in advance, from the the previous seasons, what strains of flu will be common. Such predictions aren't always successful especially when new strains emerge as happened with the 2009 H1N1 pandemic.

As for "don't they take quite a while to make", it depends what you mean by "quite a while". The recommendations for the "2020 southern hemisphere influenza season" which is ongoing were published on 27 September 2019 [18]. I don't know about other countries, but in NZ these vaccines started to be come available in late March, and vaccination is now in full swing. The recommendations for the "2020 - 2021 northern hemisphere influenza season" were published on 28 February [19]. I assume it's intended to be available in September or maybe October of this year [20]. In other words, it takes about 6 months for mass production of the vaccine [21] [22].

To be clear, although often the strains don't change much from year to year (see Historical annual reformulations of the influenza vaccine), even when they do the extra time is not that great. For example, with the aforementioned 2009 pandemic where the virus was first described in April 2009, the 2010 Southern hemisphere vaccine recommendations (i.e. to be released in ~March 2010) [23] included "A/California/7/2009 (H1N1)-like virus" i.e. the Pandemic H1N1/09 virus. In addition, because the virus obviously missed the 2009-2010 Northern hemisphere vaccine from February [24], special vaccines were made which began to become available in November 2009, see 2009 swine flu pandemic vaccine.

Of course this is after there has already been a lengthy process of research and development such that we have a decent understanding of how to develop and produce influenza vaccines.

Note also a vaccine for the "common cold" is actually a fairly non specific thing. As mentioned in our article, there are number of different virus strains that could be responsible. While Rhinoviruses are the most common, even then we're talking about a number of different types. So developing a vaccine against the common cold point blank is not a simple ask. It's true that we don't have a vaccine against any of the possible viruses involved, the challenges are often similar (large number of rapidly mutating strains), but at the same time there may also be specific challenges depending precisely what virus you're thinking of. [25]

In terms of SARS-2-CoV, there's still a fair amount we don't know about it. And I'm not really suggesting optimism, I'm not sure if OuroborosCobra really was either. But if we are going to contrast and compare to different examples, we should understand how these may be different or similar. Definitely as OuroborosCobra said, HIV has enough differences that there's perhaps only a little we should take away from it about probability of success, and challenges that may be faced.

Nil Einne (talk) 07:57, 18 May 2020 (UTC)

Exactly. The only optimism I mean to suggest is that we should not look to the challenge and lack of success with HIV vaccine research as something to compare with vaccine development of anything else, be it SARS-CoV-2, Ebola, Zika, etc. HIV has some extraordinary (and I mean that in the literally sense, as in "extra and beyond the ordinary") properties and challenges that are not an issue for any other virus that I am aware of. As you say, we don't yet know enough about this coronavirus to say for sure how easily it will be to vaccinate against, but given the 100+ promising vaccines currently in development, I'd say our chances are more towards either a truly effective vaccine, or possibly something more like influenza and a need to regularly re-vaccinate. I also always hate the description of the influenza vaccine as "not working well." It works great. As you said, the issue is in predicting the strain, but when the strain is predicted right, it gives near 100% protection. Even when they get the strain a bit wrong, the flu vaccine greatly reduces the severity of the flu. We have a problem in the US, at least, of not enough people getting vaccinated every year. If we did, we would have a lot fewer flu related deaths than we do now, because the flu vaccine is highly effective. --OuroborosCobra (talk) 13:46, 18 May 2020 (UTC)

Thanks, that’s important information that I didn’t know.Rich (talk) 15:40, 18 May 2020 (UTC)

North Magnetic Pole rapidly shifting

Is this article true? What would the implications be for the economy? EllenCT (talk) 04:56, 17 May 2020 (UTC)

Is it true that the NMP has been moving? Well, many scientists have been tracking this movement for years.

Is it true that the cause is as described in the article? It's the best explanation we currently have: you can read the abstract of the original scientific paper here for free, or read the whole thing for a modest fee, and decide for yourself.

What are the implications for "the economy" (whose?)? In the short term, there'll surely be more economic activity in the sectors concerned with global navigation, as maps and systems will continue to need adjustments and amendments. Longer term, changes in the details of how the Earth's magnetic field shields higher latitudes from geomagnetic storms may mean more (or less) damage to electrical systems, mains electricity grids, communications, navigation systems, satellite hardware, pipelines and doubtless other things. As an economics student, you are better placed to research and opine on such matters than I.

No doubt others have more knowledge in these fields and can add further details. {The poster formerly known as 87.81.230.195} 90.197.24.23 (talk) 06:37, 17 May 2020 (UTC)

The paper on which this pop-science article is based appeared in Nature Geoscience ("Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation"). It is behind a paywall and I did not read it, but "lobes of negative magnetic flux" as mentioned in the abstract are not "massive blobs", nor do I expect the paper to describe these lobes as "writhing" and "duking it out" to each other. In the abstract, the authors ascribe the faster motion (about 2 mm/s compared to an earlier 0.5 mm/s) to "elongation of the Canadian lobe, probably caused by an alteration in the pattern of core flow between 1970 and 1999". As a result, magnetic north is now very close to true north. There is no indication that the global magnetic field has weakened, only that its orientation has changed. I see nothing that looks like it might have implications for economic activity.  --Lambiam 08:07, 17 May 2020 (UTC)

One implication is that in the UK, compass navigation is much easier because magnetic variation is insignificant in most parts of our island, here in London it's only 1° and decreasing. [26] Hooray! Alansplodge (talk) 11:22, 17 May 2020 (UTC)

And, also in the UK, our national broadcaster has seen fit to publish a nice animation showing that this is nothing new. [27] Bazza (talk) 16:22, 17 May 2020 (UTC)

Although (according to the BBC animation) it's moved more in the last 30 years than in the preceding 150 years. Alansplodge (talk) 12:16, 18 May 2020 (UTC)

Pleurisy and dancing

Why was Anna Pavlova told that she could not dance ever again if treated surgically for pleurisy? The article on pleurisy is silent on this subject.--Jasper Deng (talk) 18:32, 17 May 2020 (UTC)

I'm thinking there's a lot of legend wrapped around Pavlova's demise, in particular the "refused an operation" part. Victor Dandré's account indicates nothing of the sort.[28] --jpgordon^{𝄢𝄆 𝄐𝄇} 05:02, 18 May 2020 (UTC)

The account linked by Jpgordon is persuasive. However, assuming for the moment that the "refusal" story were true, the Pleurisy article suggests that the principal (only?) long-term surgical treatment for the condition is Pleurodesis. This would necessarily mean that the functionality of the Pleural cavity would be eliminated, which in turn would surely compromise the patient's peak lung function such that they would thereafter be unable to perform vigorous physical activity, such as dancing. {The poster formerly known as 87.81.230.195} 90.197.24.23 (talk) 07:53, 18 May 2020 (UTC)

May 18

Neopentane

Pentane, isopentane, and neopentane are all isomers of C
₅H
₁₂. Their boiling points are (repectively) 36 °C, 28 °C, and 9.5 °C, with a decreasing trend as would be expected with increased chain branching and the resultant weakening of dispersion forces. Their melting points, however are (respectively) −130 °C, −160 °C, and −16.6 °C. Can anyone explain or point to an explanation for the melting point of neopentane being so much higher than that of pentane and isopentane? The WP page on neopentane mentions the difference but its explanation is not clear to me. Help! 112.213.147.109 (talk) 09:00, 18 May 2020 (UTC)

You may find the explanation in this paper cited in the article easier to follow. Mikenorton (talk) 09:06, 18 May 2020 (UTC)

mask that only covers mouth, how effective for preventing spreading it to others? How effective as a protection for oneself?

Is it really needed stopping spreading, since ones mouth spreads most of the saliva, and you can pull the mask upwards if you're about to sneeze? And for protecting oneself there's a lot more barrier through the nose. It seems to me one is recirculating carbon dioxide which could be a health risk for some people.144.35.116.6 (talk) 22:24, 18 May 2020 (UTC)