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December 7[edit]

Physics - battery questions.[edit]

What makes a rechargeable battery, a rechargeable battery, and a non-rechargeable battery a non-rechargeable battery? I'm not looking for a philosophy answer, which is "1 is where the reactions can go in the backwards direction." That's an answer a pure philosopher can say, I'm looking for more of a science answer, which I think is more than just different materials or elements. (talk) 00:01, 7 December 2018 (UTC).

Notice that batteries considered non-rechargeable, like alkaline ones, can be recharged, but not at home simply by electrical means. Primary cell has many leads that can be followed to understand the difference. --Doroletho (talk) 01:06, 7 December 2018 (UTC)

Indo European languages: A Disease Hypothesis[edit]

Marija Gimbutas's theory for the widespread prevalence of Indoeuropean languages is, roughly, that the conquering power and range of mounted Indo european horse warriors made the language spread rapidly and widely. Colin Renfrew's theory might, roughly, be that the original indoeuropeans spread rapidly and widely because of the new farming techniques they introduced when they migrated and when the new kind of farming was accepted by the people they met, the indoeuropean language tended to be accepted or prevail. What I'm wondering is, if instead, the Indo Europeans probably innocently carried some kind of terrible disease, such as plague, that they were resistant to, and the peoples in the places the Indo Europeans migrated to were then wiped out by the disease. The reason I'm thinking this is I read part of the article in the Atlantic that just appeared about the plague killing people in Sweden 4900 years ago. The events discussed might be entirely unrelated to an IndoEuropean diaspora, but gave me the idea, which I bet isn't original to me. So if there is information available about this or if you can give reasons why the idea is good or bad, i'd appreciate it. Rich (talk) 02:45, 7 December 2018 (UTC)

The genetics of people are different to the history of the language. The ancestry of the speakers gives a different story to the language grouping, so it appears that people living in an area adopted the language. Also it appears that the Indoeuropean languages spread in the Bronze age, and not with the introduction of farming (Neolithic). Graeme Bartlett (talk) 04:49, 7 December 2018 (UTC)
Not following your reasoning144.35.45.56 (talk) 05:58, 7 December 2018 (UTC)
You seem to assume that the Indoeuropean languages spread because their speakers largely replaced the previous inhabitants speaking other languages. If that were the case, than the phylogenetic tree of the Indoeuropean people would look very similar to the phylogenetic tree of the Indoeuropean languages. But if we look at the actual relationships, it seems as if the languages spread primarily by being adopted by the existing population, not by a replacement of populations. Indoeuropean speakers did not replace the others, the others became Indoeuropean speakers by learning the language. --Stephan Schulz (talk) 08:22, 7 December 2018 (UTC)
In the Portuguese and English speaking countries in the New World, speakers of Indo-European languages certainly replaced the local population. I'd say by germs and steel. In the Spanish speaking countries there, partially too. --Doroletho (talk) 14:22, 7 December 2018 (UTC)
That it happens in one place, doesn't mean it happens in all places, all the time. The way in which a language moves into a specific geographic area, and sometimes it is because one population displaces another, sometimes it is because the population stays where it is, and the language changes. --Jayron32 14:55, 7 December 2018 (UTC)
Sure, according to Indo-European migrations the expansion wasn't always violent. the colonization of the Americas was just the last chapter of the whole story. But with a population of 1 billion, the continent is a significant share of all speakers of Indo-European languages.--Doroletho (talk) 18:07, 7 December 2018 (UTC)
Perhaps you are thinking of this? Abductive (reasoning) 05:03, 7 December 2018 (UTC)
You have to ask why people would bother speaking a language like Indo-European. If people start out speaking a language with a very rich grammatical structure where there is a massive redundancy in each sentence, then over a just a few generations that language will be end up being simplified, redundancies will be eliminated, grammatical constructions that are not needed will go out of the window. So, the idea that local people had spoken Indo-European amongst themselves is not so credible, they certainly would not have adopted that language in the sense of stop speaking their own language and decide to speak Indo-European. What happened was that Indo-European was their version of today's English or the Latin on previous centuries, i.e. a language needed to communicate with people living elsewhere who speak a different language. Then over time Indo-European would have influenced local languages, just like English has had an influence on many languages. This could then have led to the local language being end up replaced by Indo-European on the longer term, but at the end of any such replacement process a severely bastardized form of Indo-European would be spoken. Count Iblis (talk) 18:31, 7 December 2018 (UTC)

What type of spider is this?[edit]

PseudoSkull (talk) 04:26, 7 December 2018 (UTC)

Too much hygiene[edit]

Has there been research done / is there a medical consensus on whether there can be such a thing as too much hygiene, whether at some point being extra meticulous about it doesn't decrease or even increases a person's chance of getting sick in the future? A while ago I read about a study that found that people drinking 2 units of alcohol per day had fewer colds than those who didn't drink at all. Assuming that this isn't due to famed beneficial effects of alcohol, it would indicate that people who drink a lot have a lifestyle that has them experience less colds (despite that I expect these people are less careful about their hygiene, not to mention that they suffer from alcohol's known deleterious effects). Are there more studies suggesting similar conclusions? (talk) 04:49, 7 December 2018 (UTC)

See Hygiene hypothesis and Alcohol and health. Graeme Bartlett (talk) 04:51, 7 December 2018 (UTC)
Anything specifically about the effects of adult lifestyle? Hygiene hypothesis seems to be only about how childhood hygiene affects later life. As in, for example, do people who have a high degree OCD about cleaning get sick less often than, say, the person with 80th percentile hygiene? (talk) 05:58, 7 December 2018 (UTC)
Most recently I've heard it's best to not avoid everyday bacteria, since exposure to them keeps your immune system and microbiome in shape. So they stopped selling (or at least recommending) antibacterial soaps.[1] If you're OCD about cleaning (so you're not exposed to anything) but then you slip up, you can supposedly get infected more easily than someone with stronger immunities. This was interesting. (talk) 07:28, 7 December 2018 (UTC)
For clarity, the recommendation against antibacterial soaps is not simply because of concerns they may interfere with the normal microbiome (and other possible negative effects), but also because we don't really know that they even reduce bacterial load on the skin. Just because something has an antibacterial effect and is useful in some situations doesn't mean it's going to be the same in all situations. See e.g. [2] and also [3] and [4]. This is not to disagree that there's increasing recognition disruption the normal microbiome can actually make things worse. E.g. our Human microbiota article links to this somewhat old (and popular science) source [5] Nil Einne (talk) 07:45, 8 December 2018 (UTC)
Another relevant item, but still relating to childhood, is the history of poliomyelitis. It was only in the 20th century that polio began to afflict people in large numbers, and this is believed to be the result of impoved sanitation stopping people from getting it during early childhood when it is less dangerous. -- (talk) 07:37, 7 December 2018 (UTC)
Thus getting cholera instead of polio. ←Baseball Bugs What's up, Doc? carrots→ 08:30, 7 December 2018 (UTC)
Most of our modern lifestyle habits we stick to have never been subject to rigorous scientific tests. If we now get suspicious that some aspects of our modern lifestyles are not so healthy, then we'll investigate but we'll do so giving our current habits the benefit of the doubt. So, the null hypothesis will be that whatever we're dong now is good, and we require a statistically significant result for an alternative hypothesis. This means that we'll keep up with a lot of put very unhealthy habits as we're not going to be able to do all the research necessary to debunk all of our habits that we've adopted throughout history without a shred of evidence. Count Iblis (talk) 17:50, 7 December 2018 (UTC)

Theoretically speaking, is it possible to reverse plastination?[edit]

I have heard about plastination being an alternative to cryonics. Obviously we don't have any way to reverse plastination right now, but I was wondering if reversing plastination is theoretically possible. In other words, I was wondering if it was possible to make a plastinated brain living once again.

Basically, if a brain is plastinated, it's possible that we might eventually be able to scan its contents onto a computer or something, but that would simply create a copy of your brain instead of actually bringing your brain back to life.

Anyway, any thoughts on this? Futurist110 (talk) 06:26, 7 December 2018 (UTC)

If you are going to guess what method will allow revival (right now the answer is "none of them") and want to roll the dice on something besides freezing (I can see the appeal -- the idea of someone keeping that freezer repaired and running for hundreds of years without a single thaw seems really risky) why not go with Freeze-drying, followed by storage in a well-sealed container containing an oxygen free atmosphere (See Oxygen scavenger)? --Guy Macon (talk) 08:02, 7 December 2018 (UTC)
  • AIUI, very clearly not.
Plastination is a process of impregnating tissue with a polymer resin, such that it is well-preserved long-term and may be studied by looking at it with the naked eye. However it's not a process suitable for preserving microscopic detail. Structures such as cell walls are deliberately breached, so that the preserving resin gets inside them. There are similar issues in woodworking, and the manufacture of MDF boards. The simpler processes place resin around the wood fibres, but a weatherproof board such as Tricoya also requires these fibres to be made permeable or otherwise opened up, so that the resin gets inside.
As the sort of material you're presumably interested in retrieving would be at very small scales, this cell damage would be a serious problem for it.
Cryonics has the same problem. When you freeze a body largely composed of water, ice crystals form and these burst the cells. A technical problem for cryonics is in replacing the water before freezing, so that they avoid this crystal damage. Some criticisms of cryonics dispute that this is achieved long-term.
There's also the need to reverse the plastination. If there's any sort of polymerisation involved, then that would need to be reversed to make the resin non-rigid. Reversing polymerisation needs a solvent, and it's often difficult to find such a solvent which doesn't cause its own damage to other materials, such as the cells. Andy Dingley (talk) 11:49, 8 December 2018 (UTC)
Plastination can be considered a form of embalming. I have never heard about reversing it. Ruslik_Zero 20:11, 8 December 2018 (UTC)
I think your idea of scanning the contents and making a computer copy is the best chance. Why anyone would bother I don't know, would we want to revive ancient Egyptians? What would be the point? Even with the scanning it would be just to get the answers to some questions then switch them off again rather than bringing them back to life and get them to be part of society. Dmcq (talk) 21:26, 8 December 2018 (UTC)
See here:
"However, the challenge is a complex one, as the human brain contains 86 billion brain cells (known as neurons) each with an average of 7,000 connections to other neurons (known as synapses). Current computer power is insufficient to model a entire human brain at this level of interconnectedness."
And here:
"The large-scale neuromorphic machines are based on two complementary principles. The many-core SpiNNaker machine located in Manchester (UK) connects 500,000 ARM processors with a packet-based network optimized for the exchange of neural action potentials (spikes). The BrainScaleS physical model machine located in Heidelberg (Germany) implements analogue electronic models of 4 Million neurons and 1 Billion synapses on 20 silicon wafers. Both machines are integrated into the HBP collaboratory and offer full software support for their configuration, operation and data analysis." Count Iblis (talk) 03:04, 10 December 2018 (UTC)

Senses and intelligence[edit]

  1. Is there any "established" way of measuring the amount of sensory information that a brain receives? If so, how do different animals compare?
  2. Is there any known link between the development of an animal's senses and its intelligence? E.g. do animals with "better" vision tend to be more intelligent.
  3. Are there any measures by which humans have particularly advanced or capable senses?

I'm aware that these question suggest that certain attributes are better defined than they are. I know that measurement of animal (and human) intelligence is controversial, and whilst certain aspect of vision may be measurable, there is no straight answer to the question "which animal has the best eyesight?". However, I am curious if, in as much as there is agreement/have been studies, what is known/suggested.--Leon (talk) 20:55, 7 December 2018 (UTC)

Some but not all animal camouflage seem to be not good enough for humans. Predatory birds can have astoundingly good day vision though, maybe they're better at this than humans. Sagittarian Milky Way (talk) 21:19, 7 December 2018 (UTC)
In response to your third question, see petrichor and geosmin ("The human nose is extremely sensitive to geosmin and is able to detect it at concentrations as low as 5 parts per trillion"). PaleCloudedWhite (talk) 21:35, 7 December 2018 (UTC)
Ever since Gestalt, many psychologists have suggested it's not very useful to try and separate sensory input from the neurological mechanisms which are needed to use it. Aspects of the human sense of touch, for example, may not be as well developed as those in some insects, but how many other animals can read braille? Here's a 2009 comparative psychology paper entitled "In search of a unifying theory of complex brain evolution" by Leah Kubitzer, at the Center for Neuroscience and Department of Psychology, University of California, Davis, CA, which you might find interesting: [6]. Martinevans123 (talk) 21:56, 7 December 2018 (UTC)

December 8[edit]

Wind direction on a weather map[edit]

The little sticks here have a tip and on the other end like arrow feathers but only on one side. Which way is the wind going?

Also, the animated map shows wind from the west going east. I'm so confused.

Anna Frodesiak (talk) 05:36, 8 December 2018 (UTC)

And Index of meteorology articles and Glossary of meteorology need first caps per MOS:BULLETLIST I think. Am I wrong?

And where the heck is our article on those symbols on weather maps like in this map?

Anna Frodesiak (talk) 05:43, 8 December 2018 (UTC)

The wind points away from the arrows. Half stick is worth 5 knots, each stick is worth 10 knots, each flag is worth 50 knots, arrowless ring is 0 knots. 5.75, 11.5 and 57.5 in regular miles per hour instead of nautical. So an arrow of 2 flags, 1 stick and 1 half stick means 132 mph which means if you lean forward at any angle you will be blown away and bounce like a tumbleweed. Sagittarian Milky Way (talk) 06:01, 8 December 2018 (UTC)
Ah, away from the tip! So, wind goes from the tip to the flags! I've been getting it wrong all this time. It's like the clam chowder thing all over again. That clears everything up.
Now, about that symbols article?
Many thanks! Anna Frodesiak (talk) 06:16, 8 December 2018 (UTC)
The wind blows in the direction of the arrow, so a west wind is shown as an arrow from west to east (left to right if north is at the top). It's called a west wind because it comes from the west, so if you face west it will blow in your face. Dbfirs 07:52, 8 December 2018 (UTC)
Left to right, correct?
Hi User:Dbfirs. So, left to right according to that image, correct? Anna Frodesiak (talk) 11:18, 8 December 2018 (UTC)
Yes, I always imagine an arrow head on the opposite end to the speed flags. Dbfirs 11:54, 8 December 2018 (UTC)
Thank you!! Anna Frodesiak (talk) 12:32, 8 December 2018 (UTC)
The same way as a weather vane indicates wind direction, by pointing to where it's coming from. [Apparently NOT. Confused me too!] ←Baseball Bugs What's up, Doc? carrots→ 12:57, 8 December 2018 (UTC)
What????? Oh dear. Please someone explain in plain words for a dummy like me which is which. Anna Frodesiak (talk) 13:01, 8 December 2018 (UTC)
The thing points to the right because the wind is coming from there, like a weather vane, right?

Sorry, all. You've been saying it plainly all along and I've been misunderstanding. I get it now. My humblest apologies. I just had to get my head around it. My brain has been trained my whole life to see an arrow meaning the direction of motion. With these wind things, it is opposite. Anna Frodesiak (talk) 13:21, 8 December 2018 (UTC)

This says wind is "NE". Shouldn't they say SW, as in coming from the SW? [7][8][9] and press play show the wind is coming from the SW. Anna Frodesiak (talk) 13:28, 8 December 2018 (UTC)

MOS:BULLETLIST states Prefer sentence case, rather than making it mandatory. My preference for the long lists you referenced is to use lowercase except for terms which conventionally start with an uppercase letter (as you might see in a printed book's index); it seems to make scanning the lists easier. (Btw, [10] is a nice concise list of weather symbols.) Bazza (talk) 10:47, 8 December 2018 (UTC)
And, unhelpfully, Station model describes those symbols. I tried Meteorological symbol but... Bazza (talk) 10:52, 8 December 2018 (UTC)
Hi Bazza. I'm going to make a whole bunch of redirects to that and maybe some sort of other action. I'm surprised that article gets 80 hits a day with that name. Cheers. Anna Frodesiak (talk) 11:18, 8 December 2018 (UTC)
And thank you for, which is very helpful. Anna Frodesiak (talk) 11:20, 8 December 2018 (UTC)
No I don't think that last diagram is right at all unless you are saying the arrow is pointing at where the wind is coming from which is the way normal English speech goes. I believe it is the complete reverse and the wind speed indicator is at the end where the wind is coming from. It is like your original idea of an arrow going with the wind and not like a weather vane. Dmcq (talk) 13:42, 8 December 2018 (UTC)
You can check this with a weather map, the wind should go anticlockwise round a low and clockwise round a high in the northern hemisphere. Dmcq (talk) 13:56, 8 December 2018 (UTC)
It is not right, indeed. The arrow goes in the opposite direction.--Jetstreamer Talk 15:29, 8 December 2018 (UTC)
(EC) This is confusing! It's best to not consider these symbols to be arrows at all. When used on a weather map, they are often attached to a Station symbol (a circle) showing the location the reading was taken. The symbol has a line (a "wind barb") pointing in the direction the wind is coming from and has on it lines or triangles to show the wind's speed. [11] explains it nicely. There's a real example for northern hemisphere high pressure at [12] (map image at [13]), with wind from the east near Honolulu and Midway, and from the north off shore from San Francisco. Bazza (talk) 15:45, 8 December 2018 (UTC)
Thank you for providing those links, they shed light into the subject.--Jetstreamer Talk 15:58, 8 December 2018 (UTC)
If you've ever wondered what a 350 mph hurricane would look like on a weather map you'd want to see this image. That's not real, it's a computer bug that made the wind barbs reach 304.2 nautical miles per hour (292.5 to 297.5 is 10 feathers: 5 flags, 4 sticks and 1 half stick) Sagittarian Milky Way (talk) 16:09, 8 December 2018 (UTC)

Template plan[edit]

I plan to make a template that can go into weather articles. It will use the fuzzy symbols from Station model. Anna Frodesiak (talk) 12:32, 8 December 2018 (UTC)

Please see Wikipedia talk:WikiProject Meteorology#Station model symbols template.

Anna Frodesiak (talk) 12:33, 8 December 2018 (UTC)

Please say which is right[edit]

Which is right?

Now, before I burst into tears, please say which is right. Even though I made the cover of Daft Monthly twice, this still seems objectively confusing. I've read some of the above to others here, and they are confused too. It is about language and describing wind sources and direction of travel and what wind going away from tips of arrows means and such. It's making me nuts.

So, A or B? Thanks for your patience, all. Anna Frodesiak (talk) 21:19, 8 December 2018 (UTC)

According to the University of Illinois, B is correct.[14] PaleCloudedWhite (talk) 21:32, 8 December 2018 (UTC)
B! Good. Sorted. Thanks, PaleCloudedWhite. Sooooo, not like a weather vane at all. And quite the opposite of an arrow too. Anna Frodesiak (talk) 22:46, 8 December 2018 (UTC)
Yes, the opposite of a weather vane. But it IS like an arrow, IF you take the little speed marks to be the "feather" and the little circle or dot at the other end to be the "arrowhead". ←Baseball Bugs What's up, Doc? carrots→ 23:19, 8 December 2018 (UTC)
An arrow? Quite the opposite. If it were like an arrow, then the fletchings would not be pointing into the wind. Ha! :) Anna Frodesiak (talk) 23:32, 8 December 2018 (UTC)
Since when do arrows fly tail-first? A weather vane points to where the wind is coming from. These arrow-like things the weather bureau uses point to where the wind is heading. Which is exactly what option B in your diagram shows. The descriptions had me confused too. ←Baseball Bugs What's up, Doc? carrots→ 23:39, 8 December 2018 (UTC)
What you are saying about arrows seems backwards to me. The tip of the arrow is where the wind is coming from as the arrow flies through the air. As the arrow moves, the air flows over the arrow toward the fletching. The wind barb is the opposite. The fletching, or little marks, is where the incoming wind hits first. That is the opposite of an arrow, right? Anna Frodesiak (talk) 23:55, 8 December 2018 (UTC)
By either your interpretation or mine, the net effect is an arrow which is pointing in the direction of the wind's flow (your option B). That's the opposite of a weather vane, where the arrow is pointing to where the wind is coming from (your option A). ←Baseball Bugs What's up, Doc? carrots→ 00:02, 9 December 2018 (UTC)
This is nuts, eh? :) To me, the arrow flies into the wind rather than following it. And this is not the first time I've noticed this ambiguity. A friend had problems with a tire once. Search "Now grab the new tire" here. I think it can all be seen two ways. I wonder if our brains are set up to see it only one way, or wind up confused, like me. Anna Frodesiak (talk) 00:06, 9 December 2018 (UTC)
Better! Now we all know which way the wind is blowing. Definitely moving right to left.
In your option B, the arrowhead is the little circle on the left, and the feather/tail is the "wind barbs" on the right. The arrow is pointing left, and that's also the direction of the breeze from the fan. If you want to think of the symbol as the wind "pushing" it in the direction it normally flies, that works too. ←Baseball Bugs What's up, Doc? carrots→ 00:09, 9 December 2018 (UTC)
That makes sense. By the way, I do get that it is B. My brain keeps wanting to see the arrows like a weather vane, but strangely, before this post, I think I knew it was B. You must think I'm bonkers. Also, the disagreeing maps made me wonder what was up. Anna Frodesiak (talk) 00:22, 9 December 2018 (UTC)

There! I added an image that is unambiguous. I will call the weather people and have that used from now on. (I'll probably be offline for a few months attending various award ceremonies.) Anna Frodesiak (talk) 00:27, 9 December 2018 (UTC)

<Throws hands up in horror>Oh no no, that last diagram is terrible</throws hands up in horror> That is showing an opposing force coming from the left to blow whatever comes from the right backwards so it must be showing a wind going from left to right ;-)
The difference about the arrows is whether the arrows coexist with the wind or represent the wind. In pictures of the wind they are normally shown representing the wind going the way the wind goes, whereas some here were thinking of them as fixed or going into the wind which is what weather vanes do. Dmcq (talk) 10:52, 9 December 2018 (UTC)
Hi Dmcq. The head of weather wrote back and said "The new image is lovely and the opposite of terrible and will now be used internationally from now on." That is a direct quote! SNice.svg Anna Frodesiak (talk) 20:50, 9 December 2018 (UTC)
Oh very good, it is quite nice :) Dmcq (talk) 21:12, 9 December 2018 (UTC)
Very, very lovely. They really should use your image. Looks like a fart drawing in comics where/and everybody knows where the wind is blowing from. You're a little genius, Anna! And a lovely one on top :) --TMCk (talk) 22:32, 9 December 2018 (UTC)
Thank you, Tracy. SNice.svg Anna Frodesiak (talk) 22:37, 9 December 2018 (UTC)
It's your kind and kindness that's enlightening the place.--TMCk (talk) 23:27, 9 December 2018 (UTC)
You are very sweet, Tracy. Thank you for the kind words. :) Anna Frodesiak (talk) 23:30, 9 December 2018 (UTC)

Conflicting info[edit]

[15] and [16] disagree, right?

The sat map shows a band of movement coming from the southwest heading northeast, i.e. a SW wind, right?

The graphic shows, where that same band is, barbs indicating movement coming from the northeast heading southwest, i.e. a NE wind, right?

What gives? Anna Frodesiak (talk) 22:46, 8 December 2018 (UTC)

It's B. Different layers of the atmosphere can move in different directions though. Sagittarian Milky Way (talk) 22:59, 8 December 2018 (UTC)
Ahhhhhhhhhh, I see. Anna Frodesiak (talk) 23:32, 8 December 2018 (UTC)
And the top layer of a typhoon is an anticyclone that blows the opposite compass direction because all that air it sucks has to go somewhere. Sagittarian Milky Way (talk) 00:00, 9 December 2018 (UTC)
My goodness. Weather is hard. I never realized just how hard. Anna Frodesiak (talk) 05:08, 9 December 2018 (UTC)

Case closed[edit]

A big thank you to all above who helped me understand. Your patience was very much appreciated. Anna Frodesiak (talk) 05:10, 9 December 2018 (UTC)

Yes, media weather forecasts in the UK use arrows and numbers to show which way the wind is blowing and how fast. A weather vane normally points INTO the wind, hence the confusion. Dbfirs 11:41, 9 December 2018 (UTC)
Hi,Dbfirs. Yes, it is that darn weather vane that forces my brain to switch the wind directions. I have it now, I'm sure. Many, many thanks! Anna Frodesiak (talk) 20:50, 9 December 2018 (UTC)

Cartography: bearing from one city to another[edit]

Every night I place my watch (in Los Angeles) so that it is pretty much pointing to WWVB in Fort Collins, Colorado. Is there an easy way to tell what compass heading points to Fort Collins from Los Angeles? I just looked at a map and eyeballed it. --Guy Macon (talk) 19:22, 8 December 2018 (UTC)

I've never had a radio clock, what happens if you leave the watch (strap?) pointing somewhere else? Sagittarian Milky Way (talk) 19:42, 8 December 2018 (UTC)
It appears to have a typical "figure 8" pattern, where you just have to be kind of close to the correct direction, to get a good signal, and you have to be at exactly 90 degrees sideways to get no signal at all. Mostly I ask asking because I am curious whether there is an easier way than using the Haversine formula. --Guy Macon (talk) 05:39, 9 December 2018 (UTC)
[17] suggests that in Los Angeles a heading of 54 degrees will point you at Fort Collins. If you start walking, though, you'll need to gradually veer to 62 degrees. Bazza (talk) 19:59, 8 December 2018 (UTC)
An azimuth map may help. Greglocock (talk) 23:30, 8 December 2018 (UTC)
Incidentally the maths to do it right are not really beyond a high school student, although I suspect most high school students would disagree. Greglocock (talk) 23:32, 8 December 2018 (UTC) is one of several sites that will compute a great circle route from one airport to another (or between any places, but it's designed to work most easily with airport codes, and allows you to look them up by place name). It also tells you what direction the initial compass heading is. From Los Angeles International to Ft. Collins / Loveland Airport, the answer is 55°. In the other direction it would be 243°, so if you followed the great circle from Los Angeles, your bearing would gradually change to 243°−180° = 63°. -- (talk) 05:52, 10 December 2018 (UTC)
I may be clueless on this, but my impression is that the angles on a Mercator projection are true - you can simply read the angle off the map and go that way. (Our article is written in Wikipedia-standard jargon about the angle being conserved, with a blue link looking down at you, that leaves it unclear to me if that is true without going on a wild goose chase) If it is true, then an algorithm to find the angle should involve doing the cylindrical projection of the two cities and looking at the angle between them. Wnt (talk) 14:34, 10 December 2018 (UTC)
Indeed, Wnt is correct. A true Mercator projection map will provide the bearing from one city to the next. You can get close - to within a few degrees - using a standard classroom-quality Mercator map of the USA. But you won't find a really good navigationally-accurate Mercator projection for the entire Southwestern United States.
You can obtain navigational-grade maps at zero cost from FAA at: VFR Charts on the d-TPP website - but you'll need to reference multiple different charts, and it may take some effort to learn how to use them.
It will also matter how you measure your bearing: are you using a real magnetic compass or some other type of instrument to determine what direction you are pointing?
For what it's worth, I calculated a 42 degree magnetic heading (approximately 52 degrees true heading) from KLAX to WWVB (to the north antenna - but I rounded to the nearest single degree). I computed this bearing using Foreflight - which is not free to use - and then I spot-checked it by hand. Interestingly, if you stand at the WWVB North Tower, the great-circle bearing to get back to Los Angeles is about 234 degrees magnetic (242 true), which is a turn-around of 192 degrees (not 180 degrees)! This is because the Earth's magnetic field is imperfect, and the amount of imperfection is quite different between southern California and central Colorado.
Using a different software tool - the zero-cost web interface at - I calculated a slightly different answer: 45 degrees magnetic (57 degrees true), which is what you could fly if you started in Los Angeles and held that magnetic heading the entire time. This is a different track out of Los Angeles, but over the entire route, it will more closely follow the great circle. Just so there's clarity on this topic: if you were really navigating an airplane or a rocket-ship over such a great distance, it would be ... unwise to depart on a fixed bearing, and then trust that you could just follow a compass heading for the entire route. That is called dead reckoning, and it has many practical limitations - not the least of which come from the complexities of the magnetic field.
It is not likely that you can point to 42, or 45, degrees of magnetic heading, with single-digit accuracy. For example, during testing, an aircraft pilot must demonstrate that they can correctly maintain a selected heading within ±5°, and that's using expensive, aviation-approved navigational equipment. If we really want to compute a bearing, we use engineered tools and navigational knowledge to make sure that our bearings are calculated in a manner that accommodates all the practical realities and errors.
Real navigation on planet Earth is quite difficult! There's a great deal of coverage on this topic in the PHAK, Section 8-23 Compass Systems and other navigational information. If you stand in Los Angeles, and you realistically expect as much as a five-degree error in your bearing, you might be pointing at a target that's almost 75 miles away from WWVB.
And if you were looking for the direct vector that went through the Earth - instead of the great circle that went along its surface - you'd have to do even more math!
Lastly, I would just point out that over very long distances in Earth's atmosphere, radio waves do not travel in straight lines: in fact, even though a lot of the transverse mode for an HF wave will propagate horizontally, the direction the radio energy is coming from can be any orientation depending on conditions. The shortest line to WWVB might be 42 or 45 degrees laterally, but the radio signal might be coming from up. For best signal reception, that means you wouldn't actually want to point your watch at WWVB: rather, you want to orient your antenna so that it picks up the strongest signal, which would entail studying exactly what the orientation describes the arriving electromagnetic waves. You'd have to measure and calculate a Poynting vector from measurements of the electric field; and it's a hard business. It's called DFing, or direction-finding; at short ranges and very high frequencies, the wave goes in a straight line, but at long range and lower frequencies, you have skywave and a zillion other effects. Here are a bunch of books on the topic.
Long story short: point your watch in any orientation; check the NIST WWVB monitor website for current conditions; and check the NOAA Space Weather website for the current and forecast K-index - a single number that rolls up how much radio interference there is. That's going to have a much bigger impact on your WWVB signal reception than the position and orientation of your watch.
Nimur (talk) 02:13, 11 December 2018 (UTC)
The Mercator says to go from 70N139W to Mecca go southeastish but when the Sun's exactly over Mecca it's almost exactly at the north horizon of 70N139W (midnight sun). Sagittarian Milky Way (talk) 04:44, 11 December 2018 (UTC)
@Nimur: I'm very surprised to hear that a "classroom-quality" Mercator map wouldn't be accurate. I mean, the GPS coordinates of every podunk town are known, and projecting them onto a sphere seems like simple math. True, the Earth isn't really a sphere, but is that aberration actually enough to cause the level of error you're describing, or are the maps just made up totally carelessly? Wnt (talk) 02:12, 12 December 2018 (UTC)
Wnt, even if the classroom map is flawless, it almost surely doesn't mark the isogonic lines - so even if you can determine the true bearing, you need some other resource (like a real navigation chart) to calculate your magnetic bearing - assuming you want to use a magnetic compass. How else would you determine where in the real, outside world to actually point at in correspondance with some flawless line on the map? Stellar alignment? Perhaps you have technology - but your smart-phone compass still points at magnetic north - and if your device has got some kind of software correction, you'd better understand it before you head out 10 degrees off-course! Nimur (talk) 16:37, 12 December 2018 (UTC)
I was mostly curious why the classroom map would be that bad. As for the compass bearing, honestly, I was assuming the OP was staying in a building or road that had been made to a precise east-west compass bearing by some sophisticated surveying method, or otherwise could look up the apparent angle on some kind of satellite map; but in any case it should be irrelevant because we're talking about a low-precision process of orienting a watch on a nightstand, presumably without help of a sextant. ;) Wnt (talk) 12:49, 13 December 2018 (UTC)
Per my usual demeanor, I'm simply trying to hold everything to the highest possible standard of accuracy and precision! Clearly, most classroom maps will serve well if you just want a rough estimate of the direction from LA to Denver. Your classroom-grade protractor probably has more precision-problems than the chart itself. But neither is as accurate or precise as a real navigational chart. If you really like maps (and charts), you'll want to use something a little better than what they sell in the local bookstore.
In my opinion, you'll just find that the quality-standards for most cheap printed-paper maps really aren't navigational-grade. If you look at an approved navigation chart for a ship or an aircraft, you'll see a lot of ancillary details - like how exactly to line up the paper so it overlaps with precise navigational accuracy. The front page of a folded government air navigation chart actually contains printed instructions for the procedure of plotting a straight line between two points, even if it crosses multiple sheets of paper.
The charts also contain the important legal-ese phrase, "... published from digital files compiled in accordance with ...(detailed) specifications." I bet you won't find that phrase on a classroom wall-chart!
Here are some authentic chart resources for the United States of America:
Outside the United States - even our neighbors in Canada - such resources are not always made available at zero cost. For example, in Canada, even digital copies of Government-approved navigation charts are sold by subscription via Nav Canada, and in my experience, they are more expensive than the cost of commercial subscription providers for paper or digital copies - like ForeFlight or Jeppesen. If you travel to the far-flung reaches of the planet, and you want a good navigational-quality Mercator map, you can buy those too. The U.S. Government used to provide, for a brief time, world-wide navigation maps (in paper and digital format) at zero-cost; but these are no longer kept current, nor are they free to users.
Nimur (talk) 19:27, 13 December 2018 (UTC)
A straight line on a Mercator map represents a rhumb line: a path whose angle to the local meridian is constant. It is not a great circle, which OP presumably prefers. —Tamfang (talk) 02:40, 13 December 2018 (UTC)
That's what I was getting at with my post a few posts up. Though it takes many miles or high/Antarctic latitude for the difference to become noticeable. Sagittarian Milky Way (talk) 04:01, 13 December 2018 (UTC)
Ah, that's the heart of the matter, and a reason not to trust Mercator after all. (that and making Russia look way more intimidating than it should be ... our article deflates it nicely) Wnt (talk) 12:53, 13 December 2018 (UTC)
Tamfang is absolutely correct. A rhumb line is not a great circle; and neither is a representative characterization of the actual path that an HF radio wave will travel over great distances. HF radio waves will bend and bounce, (refract and reflect), all subject to the imperfections of Earth's atmosphere, magnetic field, and lots of weird details of physics. Nimur (talk) 19:31, 13 December 2018 (UTC)
In 2004 I wrote a program to calculate the distance and bearing between two points on Earth. Well, the old EXE won't run because of a missing DLL and I can't recompile the Windows version because some tools I used for the interface, I no longer have. But I put in 34.03N, 118.15W for L.A. and 40.56N, 105.08W for Fort Collins and had it runthe calculations. It returned the bearing of 305.98 degrees NW, which I think means 54.02 degrees East of North. The distance is 1362.10 km, 846.37 statute miles, 735.47 nautical miles. Bubba73 You talkin' to me? 03:35, 11 December 2018 (UTC)
What I needed instead of Mercator was a gnomonic projection ... invented by Thales of Miletus in the 6th century BC, according to our article, perhaps not coincidentally also the first person known to have written about lodestones. I feel behind the times. But these aren't true to area or angle, so apparently the great circle route is worked out on a gnomonic map, then transcribed to a Mercator map to read off the angles? Wnt (talk) 21:57, 13 December 2018 (UTC)

December 9[edit]

Why does my smartphone have such a hard time reading my fingerprints when my sympathetic tone is elevated for long periods or concomitant with an NMDA receptor antagonist?[edit]

I don't want medical advice. I'd just like to know the scientific reason why when my sympathetic tone is very high (along with blood pressure and pulse) due to NMDA receptor antagonist use why my smartphone struggles to read my fingerprints. I've observed this phenomenon for about 4 years for about 15-20 such experiences. It refuses to authenticate and I've actually accidentally reset my phone this way due to security measures. I've tried to make my phone recognize an alternate set of fingerprints, but it turns out I have almost no trainable fingerprints at all in this elevated physiological state! Why? When my physiological state returns to normal (about 12-36 hours) my phone recognizes my fingerprint again, so this is a fairly long recovery process. My hypothesis is that acute dehydration leads to blurring of the fingerprint ridges. Am I correct? Yanping Nora Soong (talk) 01:29, 9 December 2018 (UTC)

Also, I just read this article -- would the following causes: high blood pressure + vasoconstriction + hypovolemia + electrolyte imbalance + skin becoming cold due to activation of the fight or flight response for 6-24 hours at a time -- lead to a fingerprint capacitance signal outside the range of most fingerprint readers? Yanping Nora Soong (talk) 01:36, 9 December 2018 (UTC)

Most likely it's a combination of sweaty skin (increased sympathetic tone increases sweating) and the effects of vasoconstriction changing the elasticity, etc. of the skin. My smartphone has been unable to read my fingerprint with damp hands, either from sweat or handwashing. There are many types of fingerprint sensors, but I believe pretty much all smartphones on the market use either optical or capacitive sensors. Damp skin will interfere with both of these, either by blurring the image or changing the skin's electrical conductivity. -- (talk) 10:22, 9 December 2018 (UTC)
As an aside, the term "sympathetic tone" (as linked by the OP above) redirects to Sympathetic nervous system, which uses the term only once without defining what it is. Perhaps someone with expertise in this area could add some clarification there? {The poster formerly known as} (talk) 23:26, 9 December 2018 (UTC)
It's a qualitative way of referring to the activation of the sympathetic nervous system. The parasympathetic counterpart is vagal tone -- and I suppose vagal tone often dramatically decreases during these experiences as well. Yanping Nora Soong (talk) 03:07, 10 December 2018 (UTC)
I don't really know if NMDA receptor antagonists generally affect the sympathetic nervous system, nor can it be assumed that such effects must include sweaty fingers, so it would seem productive to do an empirical test: wash and dry your hands and see if that addresses the issue. If not, it is very possible we might actually have to find out how the sensor works, whether it is affected by vascular flow, whether that flow (or some other measuring mechanism) is affected by the specific drug etc. in order to get anywhere. Personally I'd say tossing the "smart" phone and relying, as needed, on a burner that never heard of fingerprints and costs $10 to buy and $80 a year to maintain would be the smarter move, but that's just me. Wnt (talk) 14:04, 10 December 2018 (UTC)
Even I wipe my fingers (I've observed this for years) and smartphones in general refuse to authenticate me until I am no longer tachycardic again and my vitals return to baseline (which can take 48-72 hours). I'm pretty sure I have elevated sympathetic tone, exacerbated by anticholinergic effects because emergency department physicians have told me and in fact introduced me to the concept of sympathetic tone and I don't want to discuss any medical details because that would risk making this a medical question. Yanping Nora Soong (talk) 17:59, 11 December 2018 (UTC)
For the experiment I suggested "wash and dry" to be sure that salt or other substances are excluded from consideration. But I also have to ask -- does this occur to anyone else? I mean, there are a lot of agitated people who make phone calls. If somebody set up a fingerprint reader to "secure" their phone against whoever is so unimportant that they can't compel fingerprints and then that user can't call 911 because they're too frightened, I would laugh and laugh... Wnt (talk) 02:19, 12 December 2018 (UTC)
Most phones can call emergency numbers without unlocking. Most phones also have a backup unlock normally via PIN, pattern or password if the person can't use the fingerprint unlock for some reason. Nil Einne (talk) 10:44, 12 December 2018 (UTC)


What makes riding a bike, swimming, driving unforgettable? I surely see the advantage of it, if you learn how to hunt, you'll keep this knowledge until the new huting season. However, what makes it like that? Are only motor skill in this category? --Doroletho (talk) 17:30, 9 December 2018 (UTC)

See Rote learning and Muscle memory. ←Baseball Bugs What's up, Doc? carrots→ 18:35, 9 December 2018 (UTC)
Motor learning occurs in the premotor cortex rather than in the hippocampus like many forms of recall. There actually is a short-term form of motor memory, which means that it is not always "unforgettable" (see [18] for an introduction and [19] for the article) but we seem to think less about it, I suppose. Wnt (talk) 14:13, 10 December 2018 (UTC)

December 10[edit]

What's the largest (smallest sphere containing van der Waals surface) molecule that's single bonds in a hub-and-spoke shape?[edit]

Tetrahedral protactinium tetratantalide? Mononeptunium heptatantalide?

And what's the largest diatomic molecule? Francium astatide? Francium tantalide? Francium ceside? Difrancium gas? Sagittarian Milky Way (talk) 02:31, 10 December 2018 (UTC)

I was thinking you could get the longest bond length out of a noble gas (taking care not to make it infinite!) so something like tetraxenonogold(II) might be a step in the right direction, though that's an ion, so it won't count any more than dixenon cation. No idea if anyone has ever been nuts enough to make tetraradonogold. This "source" [20] claims that "The longest known bond length occurs in the Noble gas compound Xe2Sb2F11. The Xe-Xe single bond in this compound is 3.0871 Å." I haven't tried to run that down, since it's also not within the criteria. Wnt (talk) 14:27, 10 December 2018 (UTC)
For diatomic see dihelium. Graeme Bartlett (talk) 20:58, 10 December 2018 (UTC)
Just to highlight a key detail from that article, the He–He distance in that compound is 52 Å (!). It's a Van der Waals molecule, however, so it's possibly not surprising that the bond is so much longer than in a normal covalent situation. DMacks (talk) 10:21, 11 December 2018 (UTC)
Tristearin 3D spacefill.png
That's about the length of this: Sagittarian Milky Way (talk) 17:21, 11 December 2018 (UTC)
Yeah, but the OP said "within a Van der Waals radius", so any Van der Waals molecule automatically fails. Wnt (talk) 02:21, 12 December 2018 (UTC)

December 11[edit]

Is 90 pounds a healthy weight for a 9-year-old girl?[edit]

I apologize if this is an extremely random question, but is 90 pounds a healthy weight for a 9-year-old girl? Futurist110 (talk) 05:49, 11 December 2018 (UTC)

Read about children's BMI from the CDC; and consider using the child BMI calculator. Their warning, verbatim: Please keep in mind that this BMI calculator is not meant to serve as a source of clinical guidance and is not intended to be a substitute for professional medical advice.
Nimur (talk) 05:56, 11 December 2018 (UTC)

You need to measure the body fat percentage of that girl. Count Iblis (talk) 07:25, 11 December 2018 (UTC)
Body water percentage can also give an indication if someone is too fat: "The figure for water fraction by weight in this sample was found to be 58 ±8% water for males and 48 ±6% for females.[2] The body water constitutes as much as 93% of the body weight of a newborn infant, whereas some obese people are as little as 15% water by weight.[3] This is due to how fat tissue does not retain water as well as lean tissue." Count Iblis (talk) 07:29, 11 December 2018 (UTC)
A weight chart is more useful here perhaps. [21] indicates that weight would be 96th percentile for a boy or 94th for a girl. So quite high. Rmhermen (talk) 10:13, 11 December 2018 (UTC)
Indeed, but there's much more to health than simple weight. If she's taller than average or has exceptional amounts of muscle, that number on the scale becomes less useful. Hence the links above that shift the discussion to metrics more directly targeted to health. Matt Deres (talk) 13:11, 11 December 2018 (UTC)
90 pounds = 40.9 kg. Looking at [22] we see that at 108.5 months, 40.5 is just under 95th percentile, and at 119.5 months, it is below 90th percentile. What that means is quite another question, as is what you define as "healthy". Can 10% of the population genuinely be unhealthy? Wnt (talk) 02:33, 12 December 2018 (UTC)
20% are obese: "In the United States, the percentage of children and adolescents affected by obesity has more than tripled since the 1970s. Data from 2015-2016 show that nearly 1 in 5 school age children and young people (6 to 19 years) in the United States has obesity.". Count Iblis (talk) 03:11, 12 December 2018 (UTC)
I feel I should emphasise what Matt Deres and Nimur have indicated. All these percentile etc stuff are interesting, but without knowing the height it's very difficult to comment on health or obesity. While BMI is far from perfect probably even more so for children, it's much more meaningful than just commenting on weight at a certain age. A quick test suggests the girl would be underweight if her height was 5 feet 8 inches (~173cm) [23]. This may be an extreme height but is probably plausible. For example Zeng Jinlian was 1.56 m (5 feet 1.5 inches) 2.17 m (7 feet 1.5 inches) at 13. Anna Haining Bates was "5 feet 2 inches (157.48 centimetres)" at 6 and "6 feet 2 inches (188 cm)" and "197 pounds (89 kg)" at 11. To be fair, such heights as these people reached are not generally healthy as indicated by the ages at death her List of tallest people#Women. And I wouldn't be that surprised if being 173 cm at 9 probably suggests she will reach a height where it starts to become a problem. But still, the weight is only a small part of that and in particular, I'm not sure that keeping a low weight, especially being underweight is likely to improve health. More to the point being 4 feet 10 inches [24] means her weight falls just within the healthy weight range. Being ~147 cm at 9. According to [25] (dunno the quality) such a height is in the 98.3 percentile. I would expect that a girl 147 cm at 9 may still end up with a height that is within the 95th or probably even 85th percentile and where it's not a significant health problem. Nil Einne (talk) 10:39, 12 December 2018 (UTC)

December 12[edit]

Science problem: Statistical solutions vs non-statistical solutions[edit]

What does it mean when an equation has a statistical solution? Like: Statistical solutions of hyperbolic conservation laws Or: Statistical solution Navier Stokes equation Wouldn't any solution be somehow a statistical solution? Wouldn't any solution be algebraic too? Could a science problem have an algebraic solution but no statistical solution, or the other way round?--Doroletho (talk) 17:57, 12 December 2018 (UTC)

Can you give a link to a specific article where you read this so we can have some context? --Jayron32 18:04, 12 December 2018 (UTC)
For example: [26] or [27]. But the question is in general. What makes a solution 'statistical'? What non-statistical solutions are there? Can statistical and non-statistical approaches to a problem differ? Or one approach, as long as it's not a blunder, will always confirm the other?--Doroletho (talk) 18:48, 12 December 2018 (UTC)
I think that means statistical in the sense of statistical mechanics. E.g. the ideal gas law is statistical. It starts with the idea of gas molecules flying in all different directions and colliding randomly. It then estimates statistical quantities like the mean kinetic energy of the molecules (i.e. the temperature of the gas) and the distribution of the energy (the Maxwell-Boltzmann distribution) without predicting the energy of individual molecules. Even in purely classical mechanics it's not possible to solve such a system exactly, but only statistically. On the other hand, if you can solve a system exactly (e.g. a simpler system involving a few billiard balls) then you can compute the statistics from the solution. (talk) 21:22, 12 December 2018 (UTC)

In what sense is a Newtonian fluid elastic?[edit]

The first sentence of Speed of sound says, "The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium." But Elasticity (physics) implies that Newtonian fluids are not elastic: "Elasticity is not exhibited only by solids; non-Newtonian fluids, such as viscoelastic fluids, will also exhibit elasticity in certain conditions..."

Yet the concept of sound compression waves seems to apply just fine in Newtonian fluid models such as the ideal gas model. Are there different senses of "elastic" at work here? For example, are ideal gases elastic media despite not being elastic substances? --Allen (talk) 20:24, 12 December 2018 (UTC)

I thought elastic just meant kinetic energy is conserved after a collision. In that sense, gases are elastic, while viscous liquids are less so. (talk) 21:17, 12 December 2018 (UTC)
Thanks. I can see how that's true of elasticity of the collisions of the constituent particles. But I can't see how that relates to elasticity of the material as a whole, which according to Elasticity (physics) is "the ability of a body to resist a distorting influence and to return to its original size and shape when that influence or force is removed." So rubber would be elastic, but not a gas (at least not in any sense that's obvious to me). --Allen (talk) 22:49, 12 December 2018 (UTC)
A guess at answering my own question: From Elastic modulus, I see that bulk modulus (which of course gases have) is one type of elastic modulus. So perhaps when people say things like what I quoted before from Elasticity (physics) (statements that imply that Newtonian fluids are not elastic), it's understood that they're only talking about Young's modulus and shear modulus. But when they refer to sound traveling through elastic media, it's understood that any elastic modulus counts. On the other hand, it seems weird to say "elastic media" in a context in which no media could possibly not be elastic. --Allen (talk) 22:49, 12 December 2018 (UTC)
Sound waves in solids can be either P-waves (compressional waves) or S-waves (shear waves), but only the P-waves can pass through a fluid, where it moves as a pressure wave. Shear wave propagation requires elastic rigidity. Mikenorton (talk) 00:15, 14 December 2018 (UTC)
Very handy for looking at the waves from earthquakes or underground nukes as they travel through the earth and figuring out which parts are liquid and which parts are solid. --Guy Macon (talk) 02:28, 14 December 2018 (UTC)

fatty acid beta oxidation[edit]

Hi all, I'm trying to understand beta oxidation of fatty acids, I've watched a few youtube vids and looked at the wiki article on beta hydroxylation but I'm still a bit uncertain! Please note, I'm trying to learn this from a human biochemistry perspective, not any other organism. From my understanding, beta oxidation cleaves 2 carbons from the fatty acid per cycle, until it is completely used up. My understanding is that acyl-coA dehydrogenase carries out the first step of beta oxidation through the process of dehydrogenation. My question is this: If only 2 carbons are removed at a time, why is it necessary for the human body to have short chain, medium chain and long chain acyl-CoA dehydrogenases? Surely it doesn't matter how long the chain is if the body is only removing 2 carbons at a time? There must be a reason why but I don't understand it. I also don't understand if there's 3 or 4 acyl-coA dehydrogenases... Any help would be much appreciated! RichYPE (talk) 20:52, 12 December 2018 (UTC)

Courtesy links: Acyl CoA dehydrogenase, beta oxidation. It looks like mammals have three acyl CoA dehydrogenases: short, medium, and long; very long chain fatty acids are first broken down in peroxisomes into medium-chain fatty acids, which are then sent to beta oxidation.
When talking about biology we need to be careful about using words like "necessary". Evolution is a "blind watchmaker". Biological systems are often not "necessary" or "optimal", just "good enough". Presumably there is some selective advantage in having specific acyl CoA dehydrogenases, or else they wouldn't be conserved. Perhaps a generic enzyme wouldn't bond well to substrates. Or perhaps the different enzymes are localized to different areas of the cell, making them more efficient. Molecules have all kinds of shapes. "Removing two carbons" is a useful model for analyzing the reactions in a schematic way, but remember that this is very reductionist. When analyzing how the enzyme reaction actually proceeds, and how different enzymes interact with different substrates, we have to look at the enzyme kinetics. There might be some research on this, but I'm afraid I'm not familiar with the subject. Maybe someone else is. -- (talk) 20:29, 13 December 2018 (UTC)
There is a bit on it here, showing overlapping specificities. Quick glance I think they said there's a C-terminal domain that controls substrate specificity, and that this was upheld in [28] later on. Now the thing to bear in mind is that there are fatty acids in a cell that are doing different things, so there is some biological imperative to control which become substrates for degradation under various circumstances, I think. After all, if all fatty acids did exactly the same thing, why would there be more than one compound available to be broken down? Wnt (talk) 22:14, 13 December 2018 (UTC)

bread vs pasta[edit]

Are they pretty much the same thing, nutritionally speaking? I.e. basically mostly wheat flour with about the same carbs, vitamins, protein, etc. per ounce of dry weight? Web search shows a bunch of "health" comparisons but no nutritional ones that I saw immediately. Question came up because of an online discussion of foods to keep around the house in case of natural disasters etc. Thanks. (talk) 21:15, 12 December 2018 (UTC)

Instead of random websites, consider using, "a USDA-sponsored website that offers credible information to help you make healthful eating choices."
If you're looking for suggestions about best practices to prepare for natural disasters, consider reading, including their suggested food preparation tips.
In particular, they recommend "dry cereal or granola" - but neither bread nor pasta make the top of the food supplies list. Remember, in a natural disaster, fresh clean water may be unavailable, and if it's really scarce, it's best to save it for drinking (not for boiling noodles). Bread is a fine food, and works well in an emergency, but compared to alternatives, it's harder to stockpile bread in large quantities.
Nimur (talk) 21:29, 12 December 2018 (UTC)
Thanks. The online person had suggested storing stuff like flour in order to bake bread, rather than storing actual bread. That sounded kind of inconvenient compared to pasta because of the long baking time. I'm not trying to do the prepper thing myself but I do have a fair amount of water and canned stuff on hand, just in case. I think it would be ok to re-use the water after cooking pasta. It's also supposedly possible to cook it by soaking it in cold water for 1.5 hours, followed by a quick (1 minute) boil, saving a lot of fuel. I might try that just to see if it works. (talk) 22:05, 12 December 2018 (UTC)
A lot depends on the type and magnitude of disaster that you're preparing for. In many conditions, water and power won't be scarce; but it all depends on what happens and where.
Here's a good free book for residents of the San Francisco Bay area: Putting Down Roots in Earthquake Country. It answers questions like... "Why should I care? Why should I prepare? What should I do?"
Plan for at least one gallon of water, per person, per day, with a three-day supply - and that's just for drinking. Anything else you want to do - like cleaning, bathing, cooking, washing, ... or handling a messy medical emergency, no matter how minor - and you'll want to stockpile a lot more water. This is the single easiest, cheapest, and most useful thing you can do to prepare yourself: even in a mega-disaster like the so-called "Big One" earthquake, you aren't going to starve before help arrives - but you might get thirsty and you'll probably get dirty.
Nimur (talk) 23:06, 12 December 2018 (UTC)
Yeah here in the bay area, quakes are the main concern. I'll look at that book. Thanks. (talk) 01:01, 13 December 2018 (UTC)
Most Italian-style dry pasta is made from durum wheat flour (usually semolina flour) which is higher in protein and contains more iron, vitamin B, selenium, and iron than common wheat. The types of starches are also different, as Durum wheat also has more amylose (30% vs 22-26%) and less amylopectin than common wheat, and amylose takes longer for your body to convert into sugar. That said, there are some rustic breads that are made from durum wheat, and some pastas (incuding most asian wheat noodles) that are made with common wheat. --Ahecht (TALK
) 19:50, 13 December 2018 (UTC)
The comparison also depends on whether the flour used to make the pasta/bread is wholegrain or refined, and whether the bread is leavened or unleavened - leavened bread provides greater availability of zinc than unleavened.[29] According to this slightly irreverant article, zinc deficiency is linked to irritability and belligerence in males, thus Edward de Bono suggested that conflict in the Middle East be tackled by making zinc-rich yeast extract available there, to supplement the zinc-deficient unleavened bread normally consumed in the region. PaleCloudedWhite (talk) 20:32, 13 December 2018 (UTC)

December 13[edit]

The need for cooler roads[edit]


I thought about it and realized that painting an asphalt road with white paint is effectively adding more work on road maintenance. Wouldn't using concrete be a cheaper alternative?--Arima (talk) 07:44, 13 December 2018 (UTC)

According to this site, asphalt has the advantages of being quicker to complete, cheaper to build (although the shorter lifespan may negate this in the long term), easier to repair, and safer. From personal experience they are also more pleasant to drive on (they have a slight give in them that makes for a smoother ride, although apparently this results in worse fuel economy). Iapetus (talk) 09:09, 13 December 2018 (UTC)
Yes, the disadvantages outweigh the advantages Concrete#Roads. (talk) 11:11, 13 December 2018 (UTC)
It isn't paint. It is asphalt with some stuff in it to make it white and a good surface coat. Dmcq (talk) 13:42, 13 December 2018 (UTC)
If you happen to be near an oil refinery, asphalt is essentially free. They try to maximize gasoline and diesel fuel but they often end up with more natural gas and asphalt then there is a demand for. --Guy Macon (talk) 17:44, 13 December 2018 (UTC)
In the UK, concrete was the surface of choice for motorways (limited access highways) but is being replaced by asphalt because it is so noisy. "Motoring groups say driving on concrete is so unpleasant that some drivers believe there is a fault with their car" - End of the road for concrete on the motorway. Asphalt getting too hot is rarely a problem here though. Alansplodge (talk) 18:24, 13 December 2018 (UTC)
And of course the noise is even more of an issue for the residents, since the road won't be driving away any time soon. Though our article on concrete roads claims there is some kind of "diamond grinding" technique to reduce it, which might be worth investigating further. Wnt (talk) 22:22, 13 December 2018 (UTC)
In parts of the world where it regularly gets below freezing, concrete cracks and spalls due to freezing water and the application of road salt. Some warmer parts of the United States have used concrete roads, but as someone that used to live there, it was not fun to drive on. Sunset Boulevard in Los Angeles was paved with concrete in the 1920s, but since it was such a busy road and concrete takes so long to cure (unlike asphault, which can be drivable within hours), it wasn't repaved until 2010 and driving on it was always very rough (and the 2010 repaving used asphault). Similarly, several of the highways in California are concrete, but since concrete is smoother and less water permiable than asphault, they had to cut "rain grooves" in the roadway to prevent hydroplaning, but these grooves can cause groove wander, where the car tends to wander to follow the grooves. --Ahecht (TALK
) 19:18, 13 December 2018 (UTC)
I think you've hit it on the head. Laying concrete takes way too long compared with asphalt. That's find when you're building a new highway, but an exasperating inconvenience when you're re-paving. ←Baseball Bugs What's up, Doc? carrots→ 01:55, 14 December 2018 (UTC)
Why are JFK's 8,400 and 10,000 foot runways asphalt while its 12,079 and 14,511 foot runways are concrete? Are the drawbacks of concrete less for (super)jumbo jets than for cars? Sagittarian Milky Way (talk) 19:54, 13 December 2018 (UTC)
Advisory Circular 150/5320-6F, which I found from the airport design and engineering standards website, "provides guidance to the public on the design and evaluation of pavements used by aircraft at civil airports."
The concrete runways are more rigid than the asphalt; this may affect aircraft performance for certain very large aircraft. For KJFK, the airport directory lists the Pavement Classification Number (PCN) for each runway. This number is affected by surface material and many other parameters.
Airport designers usually spend a lot of time studying pavement; there are entire books on how to design and build runways. Here's an entire listing of resources on airport engineering and here's a sub-page just about pavement. Oh, if I could only count the hours I've whiled away, talking pavement with airport engineers,...
From the extraordinarily thorough research paper, Porous Portland Cement Concrete: The State of the Art: "The rising costs for petroleum-based products will make portland cements more competitive with asphalt binders...", and closes by saying "commercial applications of porous concretes should be closely monitored for cost and performance data." So there you have it...
Nimur (talk) 00:43, 14 December 2018 (UTC)

What building is the most number of rooms long?[edit]

Sagittarian Milky Way (talk) 15:26, 13 December 2018 (UTC)

Hilbert's Hotel. DroneB (talk) 16:14, 13 December 2018 (UTC)
What about Earth buildings from the part of spacetime before about 2019? Sagittarian Milky Way (talk) 16:55, 13 December 2018 (UTC)
Do you mean "room" as a unit of linear measurement? Bus stop (talk) 17:33, 13 December 2018 (UTC)
Yes, so a motel 1,000 meters long with rooms every 2 meters would be 500 rooms long and probably only about 2 wide and 1 to a few high. Sagittarian Milky Way (talk) 17:57, 13 December 2018 (UTC)
The great wall of china has an really large number of towers. If you could get an estimate of how many towers and how many rooms in each, it might be the clear winner. --Guy Macon (talk) 18:02, 13 December 2018 (UTC)
It's only sort of a building, vast majority of volume and length was never hollow so you couldn't walk between towers in it, only on it. Must've been a huge amount of man-hours to build though, maybe a room every ~10 meters between towers would've actually been cheaper (but less cannon resistant). Sagittarian Milky Way (talk) 18:26, 13 December 2018 (UTC)
--Guy Macon (talk) 17:51, 13 December 2018 (UTC)

MIT's Infinite Corridor runs through several buildings so I don't know if something like that "counts". I'm sure there are longer such corridors but that would expand the possibilities. Mall of America is one building though, I think. (talk) 20:48, 13 December 2018 (UTC)

...or maybe having many small rooms is the key. I wonder how big the largest capsule hotel or self storage unit is? --Guy Macon (talk) 21:42, 13 December 2018 (UTC)

I don't know for sure, but my bet is that whatever building it is is home to a great many shelf companies. Wnt (talk) 22:23, 13 December 2018 (UTC)


Is the antibiotic bacitracin effective against the bacteria Clostridium tetani aka tetanus?--User777123 (talk) 22:15, 13 December 2018 (UTC)

December 14[edit]