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May 16[edit]

Reviewers of paper[edit]

This paper lists: "Reviewers: F.U.H., Max Planck Institute of Biochemistry; A.H., Technion–Israel Institute of Technology; and W.P.T., Vanderbilt University School of Medicine."

What does that mean? Are those the paper's referees? I thought referees were supposed to be anonymous. Is it a special PNAS thing, replacing "commnuicated by"? Clicking a couple other PNAS papers I see reviewers listed on one, and "this is a PNAS direct submission" on another. I believe in the old days PNAS was a non-refereed house journal for NAS, i.e. they'd print anything a NAS member sent in, either on their own behalf or someone else's. Maybe this is a vestige? 173.228.123.207 (talk) 16:54, 16 May 2019 (UTC)

The reviewers are the referees, by another name (although it's called peer review for a reason) - see here. See this for more information about the submission options. The reviewers can in many journals choose whether they wish to remain anonymous. Mikenorton (talk) 17:03, 16 May 2019 (UTC)
Thanks. 173.228.123.207 (talk) 09:14, 17 May 2019 (UTC)

de novo RNA-Seq on a "human-related" alien[edit]

Scenario (really for flexibility reasons): an alien species, putatively related to homo sapiens, crashes on Earth and at a certain stage in invasive biomedical investigation of the survivors, we decide to perform RNA-Seq on them. Suppose we don't know that much about their genome, that it is related enough to have human-like biochemistry but that there are possibly lots of foreign / unrelated sequences. How do you perform Serial analysis of gene expression-RNA-Seq de novo if say we are unsure of the exact variability of this related genome, i.e. we don't have an existing library? (P.S. this is a question about de novo RNA-Seq, I decided to make it about an alien species v. an arbitrary species to make the question more provocative.) Yanping Nora Soong (talk) 19:13, 16 May 2019 (UTC)

To clarify -- possibly this species has new or nonhomologous genes in their genome we don't have, but otherwise might share enough relatedness to do a meaningful comparison of our transcriptomes. Yanping Nora Soong (talk) 19:14, 16 May 2019 (UTC)

RNA-Seq is, well, shotgun sequencing. Given an alien to work with, this seems like a potentially useful technology. If the alien's RNA is a little different than Earthly RNA, then it is possible that the reverse transcription process could be 'tweaked' a bit, by screening reverse transcriptases or doing in vitro evolution on them to find some that will pair some unknown bases in the alien RNA with known nucleotides in a cDNA strand. Even if the strands had more than four bases, evolving different enzymes to do the reverse transcription differently might get 'cDNA's that could be logically compared to unravel the original sequence. (Though there is already interesting work done involving novel DNA bases to increase the repertoire... ah, Hachimoji DNA was the name)
At my guess, SAGE seems like a convenience you'd use only after you had gotten to know the alien genome quite well, at which point you wouldn't have some of the questions you suggest above. Wnt (talk) 22:37, 16 May 2019 (UTC)

Volume of non-ideal mixtures[edit]

What is the volume of a non-ideal mixture obtained from equal volumes of pure components such as water and ethanol? What info are necessary to determine this volume of the mixture, besides presumably density tables for ethanol-water? Thanks!--109.166.136.207 (talk) 21:41, 16 May 2019 (UTC)

How do the partial molar volumes and the apparent molar volumes occur in the calculation expression of the volume of the mixture? --109.166.136.207 (talk) 21:49, 16 May 2019 (UTC)

Ethanol in water is not an ideal solution, nor even a regular solution. See [1] for a basic introduction. I'll admit I have no idea how to calculate this volume, but I bet someone here does... Wnt (talk) 22:45, 16 May 2019 (UTC)
Our Partial molar property article, the target of the volume of mixing redirect, has lots of math. DMacks (talk) 22:52, 17 May 2019 (UTC)

May 17[edit]

Hi! Not a medical advice, just an article recommendation.[edit]

I'm a 26-year-old male and would like to get to know more about my disease F20 and OCD. Any article you suggest to read rather than OCD itself?, and what F20 stands for? Thank you in advance and indeed!. --LLcentury (talk) 21:32, 17 May 2019 (UTC)

There are various items under F20. Who told you that you have F20? ←Baseball Bugs What's up, Doc? carrots→ 21:45, 17 May 2019 (UTC)

My psychiatrist under prescription order for medication :) --LLcentury (talk) 21:47, 17 May 2019 (UTC)

Why don't you call his office and ask? ←Baseball Bugs What's up, Doc? carrots→ 21:50, 17 May 2019 (UTC)

I never attend her place unless for control, the orders are taken by my mother and always say "F20", and she never told me what's that and honestly, maybe my bad, I never asked what was that. Sorry the mess. I will ask her. I'm already getting to know what it is by Wikipedia article. I started not long ago with this process. Thank you. --LLcentury (talk) 21:54, 17 May 2019 (UTC)

Yes. Finding out what the code means in your case by speaking to those involved in your care is the only solution. It would be inappropriate for us to comment based on how the code may be used elsewhere. Nil Einne (talk) 04:21, 18 May 2019 (UTC)
The psychiatrist Scott Alexander (of the interesting blog https://slatestarcodex.com ) is a big admirer of the now defunct site crazymeds.us.[2] even though he says he can never recommend it to his patients (he explains why in the article). It is about treatment options and support communities for F20 and other such conditions. There is a static mirror at crazymeds.net that you can still look at if you want. 173.228.123.207 (talk) 06:03, 18 May 2019 (UTC)
"F20.0" is a billing code for paranoid schizophrenia. See here. SinisterLefty (talk) 10:56, 18 May 2019 (UTC)
Also discussed generally in ICD-10 Clinical Modification. ←Baseball Bugs What's up, Doc? carrots→ 12:23, 18 May 2019 (UTC)

@SinisterLefty: and @Baseball Bugs:, thank you for your kindness and responses to all! --LLcentury (talk) 12:50, 18 May 2019 (UTC)

The top search I found for the search hits here seems to work for this. It comes up with a series of subtypes for different numbers after the decimal. Wnt (talk) 22:37, 22 May 2019 (UTC)

May 18[edit]

When chemical properties of liquid aren't just the average of the elements[edit]

If you mix two liquids with ebullition at 100 °C and 80 °C (more or less like water and some alcohol, but I have no specific substance in mind), could the resulting ebullition be far off 90 °C?Doroletho (talk) 01:16, 18 May 2019 (UTC)

BP will be close to 90 for a mixture of equal weights, but may be slightly lower or higher than you'd expect. Raoult's law discusses this.Greglocock (talk) 04:53, 18 May 2019 (UTC)
Also the specific volume, as discussed above (though perhaps that is what prompted your question, in which case you knew that). catslash (talk) 14:13, 18 May 2019 (UTC)
Azeotropes are an extreme examples of non-average (and not even "intermediate") behavior. If you have a non-ideal mixture, you are lose a premise of Raoult's law. DMacks (talk) 16:59, 18 May 2019 (UTC)

Physics help needed[edit]

2019 redefinition of SI base units#Uncertainty of fundamental physical constants is marked as being OR. Does anyone have any sources for the uncertainties listed?

The redefinition of the base units for the metric system happens on 20 May 2019. I am hoping to get this article mentioned on the main page on that day. Alas, I also have a hot project and if I don't make my deadline because I spent too much time on Wikipedia the toy I am working on will miss Christmas. :( --Guy Macon (talk) 15:32, 18 May 2019 (UTC)

Will this change have any real, practical effect for the average human? As compared with your missing your project deadline? ←Baseball Bugs What's up, Doc? carrots→ 20:25, 18 May 2019 (UTC)
Reading that article, I ran across the curious statement that the steradian is a "dimensionless unit". I do understand what they mean, yet ... well, my philosophy is tickled. I mean, yes, there are some units that make absolutely no sense without an external standard to calibrate by (7 meters) whereas others are ratios that indicate some kind of comparison (7 mg/kg dosage). This comes up in chemistry where, for example, tracking a dilution problem can be easier if you make up a difference between "ml concentrated solution" and "ml dilute solution". But, well, the only thing is, I would have thought that the "unit" would be the external measurement whereas the "dimension" would be more of whether a measurement is curved or straight. Could it possibly be a unitless dimension? I don't know... Wnt (talk) 21:06, 19 May 2019 (UTC)
It's not unitless because the steradian is the unit. Dimension here is being used in the sense of Dimensional analysis. Dbfirs 21:29, 19 May 2019 (UTC)
Well yeah, but dimension is like mass, length, time ... solid angle? The steradian comes into being because you measure the angle in m^2 per m^2 or in^2 per in^2, and the units cancel out. It does seem like making up a unit to describe a unitless dimension... Wnt (talk) 13:39, 21 May 2019 (UTC)
Please note this apply just as well to normal angle in radian, which also is measured in meter per meter, and the unit cancel out, too. So if you think that a dimensionless unit is odd, and somewhat useless, how do you cope with angles?
Maybe this should be said this way: dimensions DO cancel out, units, not so much. The apparent area of an object afar maybe measured in m² just like the square of its distance, but is not the same "unit", so don't cancel them out, rather, call the ratio by its proper name, that is : steradian.
And also apply to Plank units: by construction, they attach the dimensions to the relevant constant, and using them just every physical equation appears dimentionless, just like a steradian.
So you just have to understand the steradian as some sort of plank unit, linked to the universal geometrical constant 4pi.
there are quite a number of SI units and SI derived units that are actually of the very same dimension of another, but are still not the same, just look at them. For instance, Candela, Lumen and Joule. And you must NOT use them for one another. And you MAY divide them, getting a number that IS dimensionless but NOT unitless.
So understand the steradian as a ratio of two different units of the same dimention: the area of a seen object, and the square of its distance. Pretty much like a Lumen/Joule would be dimensionless, but still not unitless nor meaningless.
Does that help understanding ?
Gem fr (talk) 23:00, 21 May 2019 (UTC)
Well, I'd be lying if I claimed to really understand candela and lumen in detail: we have up a picture of the photopic and scotopic luminosity functions with a little legend about the CIE curves that went into them... my gut feeling is that any unit of physics that delves that deep into biology is not going to act in the reliable way one expects of a physical unit, that there's probably some combination of strobe pulse and frequency that will end up looking totally different in brightness than the unit says it does. The use of candela = lumen/steradian seems fairly straightforward, but describing it philosophically seems different. I mean, I thought the meter was a unit. How then can meter^2 not be the same unit as meter^2? The way I'd say it is that they're different dimensions, just as length and width are different dimensions. And the partial circumference of a circle is a different dimension from the length of the tangent also. And the ratio between those has no units, but it is a ratio of dimensions, like the Golden Mean of a painting or something. But that's not how you're saying it. Wnt (talk) 12:53, 22 May 2019 (UTC)
Seems pretty obvious to me that the square of a distance (like it appears in steradian, or in calculation of gravitation force) is not an area, despite both having dimension of Length². So it makes sense to have units, like steradian AND radian, whose dimension are a number, but they are different nevertheless.
Gem fr (talk) 15:03, 22 May 2019 (UTC)
:CNN has a writeup about it,[3] though I can't vouch for its absolute accuracy - one thing being that they seem to think a kilogram is a weight. ←Baseball Bugs What's up, Doc? carrots→ 18:10, 20 May 2019 (UTC)

Does cancer cells have a specific protein structure ?[edit]

Does cancer cells have a specific protein structure ? does this protein structure is the same structure of the healthy cells ???

A good start would be to read Cancer cell. ←Baseball Bugs What's up, Doc? carrots→ 20:24, 18 May 2019 (UTC)
Protein structure is a characteristic of an individual protein. The vast majority of 30,000 genes in a cell produce proteins, each different from the others, each of which may have more than one structure. It is possible that genetic, epigenetic, or regulatory changes in the cell can alter the structure -- to give a classic example, activation of c-Src by phosphorylation will change its structure, causing it to interact differently in the cell and have more activity in stimulating mitosis (reproduction). Cancer cells can have genomic instability with vast numbers of genetic alterations in a cell, vastly different patters of gene transcription, vastly different amounts of protein present, so the protein structures likewise will follow through in being altered in many specific ways. But every cancer case is different (well, many of them), just as families are unhappy each in their own individual way. Wnt (talk) 20:58, 18 May 2019 (UTC)


May 19[edit]

Locality[edit]

For the sake of argument let's say you are observing Location A, but cannot observe Location B unless you are inside Location A, even if B is directly next to A or surrounding it on all sides. Unless you're inside A, you can't see B. Does this violate any laws of physics? déhanchements (talk) 00:39, 19 May 2019 (UTC)

So, I am observing a small hut A which is built over a shallow well whose bottom is B. I cannot observe B when outside A, only from within A.
Or, I am in a windowless attic looking down through a small hole in the floor into a windowed room A, but I cannot see out of the windows to observe the surrounding landscape B unless I am in A.
Are these examples of what you mean?
If you have something more abstract and general in mind, you might be thinking of problems in Topology, and might get a better response on the Mathematics desk. Alternatively, if you're thinking of questions pertaining to the Principle of locality, you're in the right place. {The poster formerly known as 87.81.230.195} 2.122.2.132 (talk) 02:08, 19 May 2019 (UTC)
Those are great examples, but what about this: You are observing a small hut A surrounded by a barren plain. But only by entering this hut can you now look out of the window and see, not a barren plain, but a meadow B, which surrounds the hut. The meadow and the barren field spontaneously exist. déhanchements (talk) 02:54, 19 May 2019 (UTC)
If the meadow surrounds the hut, how did you not see it on the way in? ←Baseball Bugs What's up, Doc? carrots→ 03:55, 19 May 2019 (UTC)
And that's exactly what I'm getting at. This is a counter intuitive phenomenon. You can only observe it from a certain reference point, otherwise you might say it doesn't exist at all. déhanchements (talk) 04:00, 19 May 2019 (UTC)
It's not counter-intuitive that a view of something is blocked unless one is looking from a specific vantage-point. That's the nature of nature: things look different from different perspectives. And it's beyond even a strong definition of empiricism to claim that "I can't see it myself, so it may as well not even exist at all in fact". I've heard the term "privileged perspective" used to refer to this sort of situation, though I can't find a ref for it now due to this phrase now referring specifically to societal privelege, where something looks unique (or a certain detail is only visible at all) when viewed one particular way. I was at a museum that used an actual physical model that happened to look like Penrose stairs from one specific perspective. We're getting pretty far off "science" here, no? DMacks (talk) 04:40, 19 May 2019 (UTC)
It seems like you want to ask a more specific question. For example, a mountaintop might be surrounded by cloudbanks that are only visible from the mountaintop (your "meadow") though it is entered via a "barren plain" (the steep ascent). I think you're trying to ask if the meadow and the barren plain can be in the same exact physical space in some sense, but different things are seen from different perspectives. Even there, there is all sorts of philosophical wiggle room. I mean, a hologram looks different from different perspectives... but it is the same object in the same space. Does that count? If it does, well, anything looks different from different perspectives. But if it doesn't count, then you want to define a space as "really" containing different things depending on how it's looked at, rather than (maybe) saying that the different perspectives look on different spaces ... it's hard to see where to go with this. The philosophical issue needs to be narrowed. Wnt (talk) 14:19, 19 May 2019 (UTC)
@Wnt:I see your point, I guess the only way this phenomenon could be completely separated from more normal variations of it, is if one not only saw a meadow, but could interact with it, as if the barren field was gone somehow. But that would be like walking into a ten foot house and finding out it extends outwards indefinitely inside. Needless to say there's some law that prevents that. déhanchements (talk) 17:45, 20 May 2019 (UTC)
@Yesükhei Baatar: You could do something somewhat similar with a Tipler cylinder, which would (if possible) be thought to permit travel through time. There are probably a variety of wormhole type effects somewhat related. Most involve inconceivably vast amounts of energy and types of matter that can't exist, but I feel like there are new exceptions proposed all the time. Wnt (talk) 01:05, 21 May 2019 (UTC)
Your question is not clear to me, but when a mirage makes you see things that are elsewhere, it also prevents you to see things you would see otherwise (ie, for instance, instead of seeing sand, you see a "lake"). You'll need to move (up) to see the sand again.
Gem fr (talk) 18:31, 20 May 2019 (UTC)

Dermatoglyphics[edit]

I have this article on my watchlist. A user recently added some material - it's referenced, but to a foreign language article. All fine so far, but the use of the word "modalities" is a trigger for me as it often gets thrown around in pseudoscience jargon to obscure the fanciful claims. (In fact, I'm not sure exactly what the inserted line is even claiming, but that's only a side issue for now). Is the journal cited ("Coleção Pesquisa em Educação Física") reputable? reliable? Matt Deres (talk) 12:33, 19 May 2019 (UTC)

I agree that the meaning of the insertion is unclear, and I suspect from the English-language abstract of the paper that it may not be using the word 'Dermatoglyphics' in the same sense as our article. I'm afraid I can't comment on the Journal's reliability – you might enquire on the Reliable sources Noticeboard. {The poster formerly known as 87.81.230.195} 2.122.2.132 (talk) 00:44, 21 May 2019 (UTC)
Good idea - thanks! Matt Deres (talk) 02:09, 22 May 2019 (UTC)

Stiffest material known ever[edit]

Wich material is the stiffest material knwon? might it be carbyne or is there something even stiffer?Saludacymbals (talk) 21:01, 19 May 2019 (UTC)

For a real tangible material try diamond. It would be even stiffer under pressure. Graeme Bartlett (talk) 22:34, 19 May 2019 (UTC)
Just to get us started, I'll point out that stiffness depends on the actual physical structure constructed out of the material, whereas elastic modulus is the real nature of the material itself (analogy: you seem to be asking about the nature of wood or steel, not a certain truss design built from it). And there are several different types of elastic modulus, depending on the direction(s) of the applied force and the motion resulting from it. Shear modulus might be the closest to the idea of "material stiffness" meaning resistance to bending: diamond, at 476.1 gigapascal,[4] is the largest I can find among standard materials under normal conditions (compare other entries at that ref and also [5] and Elastic properties of the elements (data page)#Shear modulus). DMacks (talk) 03:22, 20 May 2019 (UTC)

For how long can "Sarcoptes scabiei" live without having blood?[edit]

According to what I read Sarcoptes scabiei is parasitic which is nourished from blood. Then my question what happens if one lived in a apartment and he was infected with scabies, and he'll leaved his apartment for a year. Can these parasite survive there? If so, for how long? (I know that in a real case everything should be clean and washed with hot water, but this questions is more for knowledge.) 93.126.116.89 (talk) 22:28, 19 May 2019 (UTC)

I copy-pasted your question into Google. The first hit was this, which states: "Scabies mites can only live about 72 hours without human contact, but once on a person, the mites can live up to two months. Mites survive longer in colder conditions with higher humidity." According to this, their entire life span is not that long (reported estimates vary, but they're a couple of months at most). That second ref also mentions that "A study by Arlian et al. [20] found that S. scabiei var. canis females survived for a week or more when held at 15 °C (59 °F) and relative humidity (RH) above 75% (Fig. ​(Fig.4).4). At a warmer temperature of 25 °C (77 °F), females survived 1–2 days at all of the RHs tested (Fig. ​(Fig.4).4). Male survival time off the host was much shorter compared to females. These studies showed that generally, warmer temperatures drastically reduced survival time at each humidity." Matt Deres (talk) 01:08, 20 May 2019 (UTC)

May 20[edit]

What would be the first and last function to fail if?[edit]

You teleported an unshielded smartphone to low Earth orbit? (of course that's science fiction, do it in a thought experiment physics simulator if you hate teleportation thought experiments so much) What if you teleported a smartphone to a Trojan asteroid of Earth orbit? How damaging is sunlight and solar wind compared to the radiation of the rest of the universe? How many pixels fail per second? When would the screen turn off if it's set to always on? Also I'm wondering when a contemporary smartphone's GPS would stop working well if you could put it in a climate-controlled shield that only lets non-damaging radiations through and hitchhike it on a spaceprobe. Can it work outside the constellation? What velocities does GPS work at? Would it give crummy readings if you could make the receiver move at ~100 km/s relative to the satellites or a thousand or 10K or 0.999c? Sagittarian Milky Way (talk) 16:54, 20 May 2019 (UTC)

The cold would do damage before radiation in a number of ways. Shrinking pieces would crack, battery would fail, inner moisture would turn into ice, LCD would freeze and stop reponding to electric signal, the chip would fail...
Gem fr (talk) 18:14, 20 May 2019 (UTC)
The average temperature of the Earth without the greenhouse effect was about 0F if I recall so the phone average temperature might be bearable in sunlight but however much temperature differential the conduction can't remove will of course still stress the parts. Sagittarian Milky Way (talk) 01:23, 21 May 2019 (UTC)
This is wrong. Without atmosphere part of the moon exposed to the sun are close to 400K (this value depends on albedo, which is why astronauts wear white suits, so they do not roast in the sun); plastic parts will not withstand that. In the shade it drops to 3K. Average temperature do not apply to such a small object as a smartphone, it lacks thermal inertia. Gem fr (talk) 09:42, 21 May 2019 (UTC)
Could it work for seconds while the sun side hadn't heated up fully yet and vice versa? Sagittarian Milky Way (talk) 12:36, 21 May 2019 (UTC)
I dunno. Here are my 2 cents. The energy gain when lit would be in the kW/m² magnitude, a typical smartphone being ~100cm² so it gains ~10 W=~10 J/s. Specific heat capacity would be in 1 J/K/g magnitude, but it will depend a lot on whether the energy spreads on the entire 200 g typical smartphone --in which case it would heat at ~1/20 K/s, and could keep working for tens of minutes--, or first concentrate in a small, directly exposed 2g part -- in which case this would heat at 5K/s and would be destroyed in less than half a minute. Probably somewhere in between, meaning, it could work for some seconds.
For freezing, the energy loss would be 1/3 of the aforemantioned gain, so time needed would be x3.
but don't take my word for it
And check Nimur (talk) answser below. I underestimated soft error from radiation, that wouldnt destroy the smartphone but would cause critical malfunction. The average mean-time for such is not clear from his ref, though, so it all depend on whether they occur in a matter of minutes, or need more time. Gem fr (talk) 21:08, 21 May 2019 (UTC)
GPS satellites direct their antenna beams towards Earth surface. An unprepared GPS receiver needs several minutes continuous reception to acquire ephemeris and then can obtain a location in seconds if it receives simultaneously from 4 satellites. NASA report that GPS can be used (with proper equipment) as far out as geosynchronous orbit 36,000 km altitude. Simple domestic GPS receivers that have only two channels that are multiplexed amongst satellites lack processing bandwidth to handle more than about 100 mph speed. DroneB (talk) 20:34, 20 May 2019 (UTC)
As I understand it, while GPS may be able to work that far out, many GPS device you're able to buy probably won't. They still enforce the Coordinating Committee for Multilateral Export Controls (in an OR fashion) meaning they won't work above 18km altitude even though as I understand it the COCOM rules are dead and their replacement don't actually have an altitude limit. See e.g. [6] [7] [8]. P.S. Some people suggest some devices obey COCOM in an AND fashion although I'm confused by this since the COCOM text seems to be clearly OR. Possibly these devices are only complying with the Missile Technology Control Regime speed limit and people are simply confused. I think it's far rarer that people actually encounter the speed limit in practice compared to the altitude limit. So many probably don't actually know if it's obeying COCOM in an OR fashion or it's only obeying a speed limit with no altitude limit. Since MTCR seems to clearly require a speed limit, I would be surprised if devices instead obey COCOM in an OR fashion although then again I wouldn't be that surprised if whoever is in charge of implementing these limits are as confused about what they're supposed to do as random commentators, despite the fact they should have lawyers etc to tell them. Nil Einne (talk) 02:12, 21 May 2019 (UTC)
P.P.S. It is obviously possible that one or more governments e.g. the US, still had the COCOM limits in law/regulation despite the treaty establishing them ending so manufacturers did have to obey the limits or risk trouble. Nil Einne (talk) 02:17, 21 May 2019 (UTC)
Consumer GPS had a COCOM or other limit of 999mph as of some years back, but at least some of them worked fine at 500+ mph. I remember taking mine (a cheap Garmin) on an airliner just to try it out. 67.164.113.165 (talk) 06:08, 21 May 2019 (UTC)
From what I can tell the actual COCOM limit was 1000 knots. The MTCR limit is 600 m s-1. I suspect some devices were conservative because they weren't sure of their accuracy at such high speed and didn't think it mattered or because (as per the altitude limite) whoever was in charge of implementing the limit wasn't given proper guidance, but I'm not sure if these was every any legal reason for such a low limit. Nil Einne (talk) 07:29, 22 May 2019 (UTC)
How about we avoid speculation, and point our OP to a real resource?
Radiation Effects on Integrated Circuits and Systems for Space Applications, with a new second-edition published this year, is written by Raoul Velazco, research director at the TIMA Lab in Grenoble. He's a world expert on a subject near to my own personal interests: the infamous single-event upset.
In 2011, several iPhones and other consumer telephones flew on STS-135. Here's the NASA "What's Going Up" article. Some technical details are published by the experiment investigators, Odyssey Space Research, and summarized in this press release. Here's the NASA Blog article, too: SpaceLab for iOS. Among the research, the LFI (Lifecycle Flight Instrumentation) characterized the effects of radiation on the device.
To excite and inspire the community at large, Apollo astronaut Buzz Aldrin gave a presentation at Apple's World Wide Developer Conference in 2011 to show off some ideas for consumer-electronics and promote enthusiasm for spaceflight.
Here's another NASA article, Socializing Science with Smartphones in Space. They also point to a following experiment, SPHERES, in which a team of MIT student-researchers planned to emplace the smart-phone powered Nanoracks satellite outside the space station - that is to say, a smart-phone, outside, in low earth orbit.
Perhaps to the surprise of everyone commenting in the thread - but sort of expected by anyone with a little background in this area - the first thing to fail was the application software. The hardware itself was qualified for spaceflight.
If I may take a moment to grump out at this late stage of the morning, the real metaphorical take-away here is that as of this decade, the limiting factor in spaceflight is software-quality.
Interested future engineers should spend more time learning fundamentals of math, science, and engineering, and then spend a lot more time engaged in formal education relating to software engineering and computer science, so that our next generation can have exponential improvement in software quality.
Some people say that "everyone can code." The truth of the matter is, very few people can code, and even fewer people are good enough at math and science and logical thinking to code well enough for a mission-critical space-flight application.
Nimur (talk) 16:30, 21 May 2019 (UTC)

May 22[edit]

Photons[edit]

|......................................
|--------------------------------------
| < thinnest and best aimed beam that <
| < doesn't violate laws of physics < <
|--------------------------------------
|......................................
|
|
|< a bullseye

Where will half the photons fall? A wavelength wide circle? (open edit window for unscrambled ASCII art) (asked by 107.242.117.33 14:25, 22 May 2019‎)

"ASCII art" is not enough (at least for me) to understand what you mean
but anyway looks to me you'll find to be happy in Diffraction-limited system
Gem fr (talk) 14:51, 22 May 2019 (UTC)
Photon waves are used for equations. Light doesn't bounce up and down in a wave as it flies through the air. 12.207.168.3 (talk) 16:01, 22 May 2019 (UTC)
If the OP is interested in modern theory and practice to describe where we will detect photons, An Introduction to Modern Optics is a good introductory book. After reading through a book like that, let us know if you have more specific questions. Nimur (talk) 17:10, 22 May 2019 (UTC)
Basically I want to know how wide the photon equivalent of an electron cloud is. The part of the cloud that has the photon half of the time that is. Maybe the cloud won't look like a spherical galaxy since photons can't go faster than c so I made the photons fall on a 2D target. No matter how wide and perfect a laser and lens are you can't focus a laser spot sharper than this photon equivalent of an electron cloud right? 107.242.117.17 (talk) 20:01, 22 May 2019 (UTC)
You're looking for a specific technical parameter - something like a collision cross-section - to describe the interaction between a photon and some other object; but that's not a common way to model a photon. Most physicists don't talk about the photon's position in the same way that they talk about the electron cloud. And what's worse - you've somehow concluded that this number, if you could deduce it, would tell you something about "beam width." With all due respect, that's just wrong physics! So ... if you ask a wrong-physics question, there's no way to get a right-answer. In fact, this "characteristic" length scale of a photon - if we could even concoct it - would not be the thing that limits how well-focused a beam of light is, nor how wide the beam would appear if you looked at it or photographed it or otherwise sampled it.
The position of an individual photon is not well-defined until after it interacts. Instead, we use a probability density function to estimate where the photon may be, and we use experimental measurements of a large population of photons to describe where most of them will be, most of the time. This is the whole premise of quantum-mechanically correct physics. There is a small but finite probability that the photon is anywhere. We can write a wave-function to describe how improbable it would be for us to find the photon at any specific coordinate, and we can even provide characteristic scale-lengths for the wave function.
It would be wise to do some homework: study the common models that physicists use to study the behavior of light, so that you can make sure that you're asking a well-formed question.
If you're deep in it, here's Solutions of the Maxwell equations and photon wave functions, (2010), which was also published in the peer-reviewed journal Annals of Physics, authored by Peter Mohr, a professional physicist employed at NIST. This is 75 pages of very math-heavy, advanced quantum-mechanically-correct physics that answers your question. If you are not already deep in to the physics, I recommend that you start with a much simpler book, like the introductory text I linked earlier. A more simple geometric model would be the Airy disk, or the beam profile or geometry for a beam of collimated light; but these models are applicable to ensembles and not to individual photons.
Part of me wants to remind you to go back and review every permuted variations of the slit experiment, ... but part of me wonders if you've ever seen those before; if this picture doesn't jog your memory - or if you're seeing it for the first time, if it doesn't enlighten you a little bit - then you really really need to go back to studying the basic physics material.
Nimur (talk) 20:19, 22 May 2019 (UTC)
I think the OP is looking for an area containing 50% probability, if such a thing exists.--Wikimedes (talk) 22:12, 22 May 2019 (UTC)
The diffraction limit is kind of toast -- see superlens. I won't claim to know exactly when and how well you can beat the limit with what technologies. I suppose the fundamental Heisenberg uncertainty principle governs how well you can say where a photon will strike, relative to the uncertainty in its momentum ... however, if you are willing to tolerate substantial uncertainty in the left-right direction only (you don't know when the photon will hit and you don't know what wavelength it is) I don't see a way to use that to constrain the accuracy of the targeting. Wnt (talk) 22:26, 22 May 2019 (UTC)

Peach's substance[edit]

What substance in peach causes slightly burning or acrid sensation when eaten (especially on lips, similar to citruses)? 212.180.235.46 (talk) 19:33, 22 May 2019 (UTC)

Via PubMed search, I found Response to major peach and peanut allergens in a population of children allergic to peach (2015). "We study the sensitization to relevant allergens, such as peach and peanut LTP, Prup3 and Arah9, and seed storage protein, Arah2."
Pru p 3 seems to be the biological chemical name for the most common allergen in peach. This is a lipid transfer protein.
In at least one case, Anaphylaxis induced by nectarine, a peach-allergy patient reacted to nectarine, suffering a severe reaction including flush, wheals, and anaphylactic shock.
It is important to emphasize that there's a huge variety among the population. Any individual might be sensitive to other compounds, or there could be another cause for sensitivity that is totally unrelated to exposure to the peach fruit.
Nimur (talk) 19:47, 22 May 2019 (UTC)
I would be very hesitant to diagnose an allergy. Naturally peaches often have an acidic "tang" that simply results from low pH. The comparison to citruses invites this interpretation. I looked up the peach trichomes thinking there might be some silica in them (I think, could be wrong, that kiwi fruit can annoy people's lips and tongue by this means) but this paper, which goes into absolutely pornographic detail on peach skin, doesn't mention any silica I could see. Wnt (talk) 22:46, 22 May 2019 (UTC)
If you're concerned, see your doctor. ←Baseball Bugs What's up, Doc? carrots→ 23:40, 22 May 2019 (UTC)

May 23[edit]