Wikipedia:Reference desk/Archives/Science/2018 April 16

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April 16

Amine and Nitramin

I don't understand why there is written R+ or R- sometimes, otherwise there is written R1 and R2. What does the R stand for? --Saegen zeugen des sofas jehovas (talk) 00:35, 16 April 2018 (UTC)

The R refers to a side chain, basically a part of the molecule that is there but whose chemistry is not being considered at the moment for some reason. Usually the R-group is assumed to be a hydrocarbon. When multiple side chains are attached to the same molecule being considered, they are given distinct names (such as R1 and R2) so that the reader knows they are different, or at least could be. Sometimes the R group is used because what is being discussed is true for very many side chains. For instance, all molecules R'OOR" where R' and R" represent hydrocarbons have certain chemical properties in common no matter what particular hydrocarbons the R's represent. Someguy1221 (talk) 00:46, 16 April 2018 (UTC)

sounds interesting, thank you :) --Saegen zeugen des sofas jehovas (talk) 01:10, 16 April 2018 (UTC)

E Ink

Some E Ink device manuals caution against exposure to long-duration direct sunlight: "Avoid exposing your Cybook Odyssey to direct sunlight or strong ultraviolet light for extended periods of time."[1]

I trying to figure out which of the following is the real reason here:

1. Direct sunlight, more specifically the UV rays in sunlight, permanently damages E Ink displays.

2. Direct sunlight causes temporary performance issues in E Ink displays, but returns to normal after removal from sunlight. This thread[2] seems to support this theory.

3. There is no problem and this is just the standard "cover your ass" disclaimer from manufactures. The E Ink article says: "Advantages of E Ink include low power usage, flexibility, durability and ruggedness and better readability under direct sunlight." Without noting any particular problems associated with E Ink displays under direct sunlight. Mũeller (talk) 02:48, 16 April 2018 (UTC)

FWIW, if you leave an LCD display, such as found on a DVM, in the Australian sun it goes black. Flip it over and it reverts to normal, eventually. Greglocock (talk) 03:46, 16 April 2018 (UTC)

Thank you for the input. Mũeller (talk) 04:35, 16 April 2018 (UTC)

There are various reports of problems with e-ink screens left in the sun here [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]. Those are all old, and you'd note inconsistent reports even within the same model, with some suggesting a few devices are particularly affected even in a very short time and you may be able to get a warranty replacement if you device is that bad.

It sounds like some the problem is a lot less with newer devices than it was before per these more recent sources [14] [15] [16]. I'd note some people suggest no problems, but others suggest there may still be problems long term. Considering the vast differences in what being in the sun can mean between users and countries, and that most people are just reporting problems they've had after a fair while with a unknown cause (i.e. it's not like they've had a random sampling of devices some of which have been left in the sun and some haven't at random and they've then compared the devices) it's difficult to really know whether any of these more recent reports of problems are due to the sun or due to something else, and if the sun can cause problems what level is required. I'd also note that most of these are simply referring to normal use in the sun, rather than just leaving a device in the sun.

In any case I wouldn't assume leaving the device in the sun has no effect since both the heat an UV are something which can have consequences, whether or not it's significant enough to be noticed in ordinary use. (I think many people who hang up their washing outdoors will now that even UV stabilised pegs last a lot shorter when left in the sun all the time even in cloudy temperate countries.) The UV can be blocked to some extent (one of the recent sources suggest one reason why some earlier devices were so affected was because production or design flaw leaving out a UV blocking filter), still there are always going to be limits considering cost, size and weight, utility and production requirements. (Also you shouldn't assume this problem is only because of the eink screen, it may be the typical use profile of a tablet, phone or laptop are such that although leaving it in the sun may cause problems, it's simply not worth warning people in such a direct way.)

Nil Einne (talk) 11:41, 16 April 2018 (UTC)

To whom mostly children similar or look like?

If I would like to know statistically to whom, in the most of the times, the children resemble genotypically and phenotypically? Do children normally more resemble to their mom or their father or their mother? (I know that it depends on genetics but I'm asking generally speaking rather than about specific cases)93.126.116.89 (talk) 04:03, 16 April 2018 (UTC)

Strictly WP:OR, but "generally speaking", babies resemble Winston Churchill and/or Alfred Hitchcock. 2606:A000:4C0C:E200:0:0:0:3 (talk) 07:19, 16 April 2018 (UTC)

Indeed. Some years ago, was reading an autobiography of a real-life Emma Peel secret agent during WWII, can't recall her name, where she remembered meeting Churchill at odd hours of the night, where his dress and appearance made him seem identical to a giant baby.John Z (talk) 20:08, 16 April 2018 (UTC)

Scientific American reported in 2011 that "Recent studies do not support the claim of an enhanced resemblance between fathers and their young offspring". Fact or Fiction: Do Babies Resemble Their Fathers More Than Their Mothers? It refers to previous studies claiming benefits to paternal resemblance. Carbon Caryatid (talk) 15:32, 16 April 2018 (UTC)

There have been more studies since then. Speciate (talk) 18:00, 16 April 2018 (UTC)

One of the things that makes these sorts of things hard to study is the lack of a reliable way of quantifying "physical resemblence". On the one hand, Biometrics can be used to assess some arbitrary degree of relatedness between two faces, on the other hand Face perception in Humans is a complex process that does not at all work like automated systems used for Biometric identification (i.e. Out-group homogeneity, etc.) --Jayron32 16:46, 16 April 2018 (UTC)

Double-blind studies show that babies resemble their fathers much more than their mothers at birth, but the effect has faded at 6 months. This has to do with preventing infanticide and uses gene silencing. Speciate (talk) 17:56, 16 April 2018 (UTC)

Do you have those studies? It would really add to the discussion to be able to read them. --Jayron32 18:13, 16 April 2018 (UTC)

Research into infanticide in animals is in part motivated by the desire to understand human behaviors, such as child abuse. DroneB (talk) 18:46, 16 April 2018 (UTC)

Sounds very unlikely to me, I bet some other paper proves it wrong. One only has to consider how many children are born from extramarital affairs and the low number of infanticides to see it would pay to make identification in the first few weeks more difficult rather than easier. Dmcq (talk) 22:39, 16 April 2018 (UTC)

Also in a study of similarity I think they really should have men compare the baby to the father and other men known by the mother. :) Dmcq (talk) 22:43, 16 April 2018 (UTC)

Like the antique joke about a child looking like the milkman. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:16, 17 April 2018 (UTC)

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