Wikipedia:Reference desk/Archives/Science/2016 July 14

= July 14 =

Before seeking FDA approval of a drug in the USA, how do they test the drugs for infants or children?
When a drug is seeking approval by the FDA in the USA, how do they test drugs for infants or children? Joseph A. Spadaro (talk) 05:16, 14 July 2016 (UTC)
 * See Clinical trial and Ethical problems using children in clinical trials (which, based on its current content, would be better at a more neutral title). Tevildo (talk) 08:25, 14 July 2016 (UTC)


 * Do you mean drugs specifically intended for infants and children? That case is rare.  Most often a drug gets approved as safe and effective for adults and is only subsequently studied in children.  In general we have articles on drug development and new drug application.  Dragons flight (talk) 08:29, 14 July 2016 (UTC)


 * Thanks. This is what I am saying/asking.  When drugs are approved for adults, they have -- at some point -- been tested on adults (through clinical trials, etc.).  Oftentimes, when we (adults) take drugs, there are warnings that say "this drug is not approved for anyone under the age of 18" (or some such).  Now, obviously, little kids (infants, children, teens, etc.) all take medicine and drugs.  So, how do those get approved for them?  I can't imagine they subject infants and children to be subjects in experimental trials and/or clinical trials.  Thanks. Joseph A. Spadaro (talk) 12:59, 14 July 2016 (UTC)


 * Ultimately, yes. Children do participate in clinical trials with parental consent.  Most often the trial is for a drug already approved for adults.  If it is life-saving medication, then the benefits will generally be viewed as outweighing the risks.  Doctors are also able to legally prescribe drugs to children that haven't been formally tested and approved for children if in the doctor's judgement such a off-label use is medically appropriate and inform the parents accordingly (usually the dosage is adjusted for a smaller body weight).  This interesting article describes efforts by the FDA to increase drug testing in children.   Dragons flight (talk) 13:12, 14 July 2016 (UTC)


 * Thanks. So, let's just look at infants, for example.  I can't imagine it's a high number of parents that allow their infants to be guinea pigs.  When they conduct tests, don't they need some statistically significant sample size?     Joseph A. Spadaro (talk) 14:30, 14 July 2016 (UTC)

Thanks, all. Joseph A. Spadaro (talk) 04:40, 16 July 2016 (UTC)

Chem elements in the infoboxes
I noticed that now our articles on chemical elements display atomic numbers alongside Latin designations in the form of 26Fe (iron), 13AI (aluminium), etc. However, I was taught in the school that an element is simply designated by its Latin abbreviation (Fe, Na, etc.), not like 26Fe. If this is related to stable isotopes, I think it's redundant. Are we doing the right thing?--93.174.25.12 (talk) 12:11, 14 July 2016 (UTC)
 * Yes, it is redundant. But I think in the infobox title (the sole place it is used) it serves the purpose of highlighting the relationship in which atomic number determines the element.  If you wish to discuss this with editors that are involved in making these decisions, Wikipedia talk:WikiProject Elements would be the best place to do so.  ChemNerd (talk) 12:15, 14 July 2016 (UTC)
 * I agree with ChemNerd. The one- or two-letter abbreviation that the OP is describing as Latin designations are correctly called chemical symbols. Only a small number are based on the Latin name for the element (eg iron is Fe because the Latin word for iron is ferrum.) The majority are closely related to the English name for the element (eg hydrogen is H; lithium is Li.) Dolphin  ( t ) 12:52, 14 July 2016 (UTC)
 * Actually, the symbols for hydrogen and lithium both derive from Greek, just FYI. EdChem (talk) 13:13, 14 July 2016 (UTC)
 * The names hydrogen and lithium indeed derive from Greek ὔδωρ γεἰνομαι and λιθος, but the symbols do not come directly from the Greek, but rather from whatever language Berzelius was thinking of when he came up with his symbols. Double sharp (talk) 15:30, 14 July 2016 (UTC)
 * Nothing to do with isotopes either - all isotopes of Iron have the same atomic number (26). The variation between isotopes lies is in the atomic weights (which range from 54 to 60). Wymspen (talk) 15:48, 14 July 2016 (UTC)


 * The atomic numbers in the lower left corner come from an expanded notation known as isotope notation. Yes, the numbers ARE redundant with the symbol, since there is a near perfect one-to-one correspondence between atomic number and symbol (excepting for the isotopes of hydrogen which each have their own symbol).  The purpose of sometimes including the atomic number is twofold.  First (and of lesser importance) is that it can serve as a sort of checksum, that is a way to make sure there isn't an error or typo somewhere.  The most important use is in nuclear reaction equations; since atomic numbers and mass numbers are always conserved in nuclear equations, explicitly writing the atomic number makes the math more visual.  -- Jayron 32 14:06, 15 July 2016 (UTC)

Deflection how much is safe?/
i have done fem study to find out deflection in structure.Is there any theory of failure to tell me that this deflection is safe or not .material is steel. — Preceding unsigned comment added by 112.133.223.2 (talk) 13:19, 14 July 2016 (UTC)


 * There are commercially available (though expensive) computer programs (doutbtless employing fem "under the hood") that can carry out such analyses, provided that the users are trained and competent in putting in all the parameters correctly. [I work in an office containing several structural engineers whose main job this is, although I myself am not one of them.] University-level courses in structural engineering and allied disciplines doubtless mention such programs, although work placements in working engineering companies might be necessary for training in using them in practice.
 * It's possible to carry out such a calculation for a single structural member on paper, but most scenarios in the real world involve complicated structures with many components, where a non-computer calculation would be unfeasibly difficult and long. (Obviously, such calculations were performed before the advent of computers, but they required vastly more personnel than would be available today, and of course some structures did subsequently fail.)
 * Given that structural failures can in many circumstances result in deaths, this is not an area that can safely and legally be dabbled in for real-world applications by the untrained. {The poster formerly known as 87,81,230.195} 2.123.26.60 (talk) 14:49, 14 July 2016 (UTC)


 * (ec) This has been studied extensively, and there are many issues here:


 * First, you need to ensure that the deformation is within the elastic deformation range, where the object will return to it's original shape, not the plastic deformation range, where it will only partially return.


 * Then metal fatigue must be considered, which is sudden fracture by a metal bent within it's elastic deformation range, an excessive number of cycles.


 * Also, the center of gravity of the building moves as it deforms, and you must ensure that the CG point is always within the edges of the foundation, or then the weight forces holding the building in place would instead work to topple it over. This is only a potential issue on tall, narrow buildings. StuRat (talk) 14:54, 14 July 2016 (UTC)


 * The basic approach would be to calculate the maximum stress of each type (which involves determining where in the structure the maximum stresses occur) and comparing these stresses to the appropriate strengths of the material. In spite of the one sentence description, this will likely be complicated.--Wikimedes (talk) 06:00, 17 July 2016 (UTC)

Is there an Aether?
The recently published book from the late Selwyn Wright backed up with several peer reviewed papers makes a very good case for an aether. This fundamentally conflicts with Einstein's relativity, but makes much more sense for measure movement from a static aether than just relative movement from two points, thus getting different equations from observer and event. He also shows how Einstein may of misinterpreted experiments to determine ether(prior to Special relativity) due to the fact that the aether turns with gravitational bodies (Also that the aether is static away from gravitational bodies in space).

Does this mean the teaching of relativity should be updated?

Selwyn addressed the experiments for aether and how they were misinterpreted but also uses later experiments to back up the claim and also suggests some other simple tests that could be done utilising the better equipment we have at our disposal today, if more proof was needed — Preceding unsigned comment added by 80.194.75.50 (talk) 14:44, 14 July 2016 (UTC)


 * It may well depend on how you define it. There doesn't appear to be much normal matter in the intergalactic void, but there may be dark matter or dark energy.  Also, you could consider the space-time continuum to be a form or aether. StuRat (talk) 14:58, 14 July 2016 (UTC)


 * The validity of Professor Wright's theory is a matter for the scientific community to decide on by the usual processes. This does not yet appear to have happened, but it's early days yet.
 * It appears to this layman that there might be a good case for a Wikipedia article on Selwyn Wright, but others would be more competent to judge. {The poster formerly known as 87,81.230.195) 2.123.26.60 (talk) 15:02, 14 July 2016 (UTC)


 * Draft:Selwyn Wright already exists, so you have something to start with. Wnt (talk) 16:33, 14 July 2016 (UTC)


 * Here's a web page on "new relativity". He's just a typical crank. There are a lot of them. His particular area of confusion seems to be the Sagnac experiment. The ten peer-reviewed papers mentioned on the web site (in the sidebar on the left) are all conference papers from Progress In Electromagnetics Research Symposium. I don't see any evidence that it's a fake conference, but it's clearly not the right venue for this type of work and their reviewers clearly don't know anything about special relativity.
 * Of course, this has nothing to do with whether Wright should have a Wikipedia article. But I see nothing to suggest that he should. -- BenRG (talk) 17:42, 14 July 2016 (UTC)


 * See also . --71.110.8.102 (talk) 23:50, 14 July 2016 (UTC)


 * If the theory becomes widely accepted by the scientific community, it will be time to "update the textbooks". Not before. And the chances are slim.
 * History_of_special_relativity contains a whole lot of evidence against aether - if it exists, it should have zero local velocity in the reference frame of any object, yet create no measurable drag on them. So that is a viscosity-free fluid that still follows the objects, and that is extraordinary. Tigraan Click here to contact me 15:25, 15 July 2016 (UTC)

Rabies vaccine "forbidden"?
Recently I got to familiarize myself with the relevant rules for transporting dogs internationally, including the rules regarding rabies vaccinations. I was surprised to learn that the country whose rules I was reviewing recognized three categories of dogs to consider:
 * 1) Dogs from countries where rabies is prevalent
 * 2) Dogs from countries declared rabies-free and rabies vaccine is available
 * 3) Dogs from countries declared rabies-free "that forbid rabies vaccinations"

In the third category, they gave examples of Australia and New Zealand. Why is there is a category of countries that "forbid" giving rabies vaccines to dogs? Is there actually something dangerous about the vaccine (e.g. a rare side effect, or something) that would justify not allowing the vaccine to be administered? Is it really true that Australia and New Zealand don't allow rabies vaccines, even for animals that will be traveling overseas? That seems very weird to me. Dragons flight (talk) 16:20, 14 July 2016 (UTC)


 * Australia recommends rabies vaccination for pets that might be exported and brought back.  Assuming you could say you want to export the pet, then cancel the trip (which might just be overnight anyway, in theory), I don't think this can be a very strong ban, at least. Wnt (talk) 16:31, 14 July 2016 (UTC)


 * Usually such rules have to do with antibody tests to detect cases of infections not working anymore. In case of farm animals e.g., you cannot export animals if you vaccinate them against foot and mouth disease. This is why vaccination is only done when there is a major outbreak and an export ban is in place anyway. Count Iblis (talk) 16:35, 14 July 2016 (UTC)
 * Yes, for a human example, some countries where tuberculosis is not widespread don't routinely administer the tuberculosis vaccine, because anyone who has had the vaccine will test positive on the tuberculin test. See: Tuberculosis. --71.110.8.102 (talk) 03:59, 15 July 2016 (UTC)


 * As with Wnt's point, these sources [//mpi.govt.nz/document-vault/7215]  would seem to make it clear rabies vaccination for pets isn't forbidden in NZ, at least for export and pets travelling outside NZ. I'm not sure if the sources saying NZ forbids rabies vaccinations are just plain wrong, misleading or outdated as I can't find any info about NZ actually forbidding rabies vaccinations. It could be the vaccine was not formerly approved for use in NZ for whatever reason. It could also be rabies vaccinations are forbidden unless export or travel is a consideration although I personally doubt this. (Although I wouldn't be surprised if a vet were to get in trouble if they don't recommend against a rabies vaccination when there are no plans for travel or export.) It could also be because rabies vaccinations are rare enough that they are potentially something that needs to be specially ordered by most vets. (I'm not sure if this is the case even in most other rabies-free jurisdictions.) Nil Einne (talk) 17:29, 14 July 2016 (UTC)
 * It seems to me that we should be asking the OP where is this example of Australia and New Zealand forbidding rabies vaccinations? Let's see the evidence for that please. Akld guy (talk) 23:13, 14 July 2016 (UTC)
 * This might be relevant. --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 02:56, 15 July 2016 (UTC)


 * The OP never said said that NZ or Australia forbid rabies vaccinations but rather that sources gave them as examples of countries that forbid rabies vaccinations. They acknowledged that the examples may not be correct and I think we've already established the claim is questionable from Wnt's and my first response. See eg   for the sort of sources the OP must be referring to. The websites all relate to Switzerland, although a bunch of spammy generic pet insurance websites also have the had the same thing. There is also one dead .nu web site I can't really understand with something similar although it seems to talk about needing proof they are forbidden and I have no idea where they were trying to export or take their pets to. Nil Einne (talk) 04:56, 15 July 2016 (UTC)
 * There is also which claims they are forbidden in Iceland. Nil Einne (talk) 05:01, 15 July 2016 (UTC)
 * I did not say that the OP said that Australia and NZ forbid rabies vaccinations. Geez, some people just love playing the game of semantics. Akld guy (talk) 06:15, 15 July 2016 (UTC)


 * Yes, this was in the context of Switzerland. Dragons flight (talk) 14:11, 15 July 2016 (UTC)

Wind strength of compressed air, part two
A few days ago I asked a question about the wind strength that would result from a sphere of air compressed from one kilometer in diameter to one-tenth of a meter in diameter. I was told that it would be as dense as a white dwarf, that oxygen-nitrogen fusion would result, and that the turbulence would require solving special equations. Really, what would happen if the force field that compresses the air were to shutdown in terms of interaction with the regular air? What would nitrogen-oxygen fusion look like? — Melab±1 &#9742; 19:32, 14 July 2016 (UTC)


 * Here is The Synthesis of Elements from Carbon to Nickel, by astrophysicist Fred Hoyle. This paper series is considered the seminal work in the field, and it explains what fusion reactions are expected to occur under various extraordinary conditions.  Well, these conditions are quite normal inside of stars - but they're very extraordinary here on earth!
 * Your hypothetical scenario is not exactly a physically-realistic condition, so you might have to be a little bit creative as you attempt to apply the results of well-established theories about stellar and supernova nuclear reactions. Nimur (talk) 20:51, 14 July 2016 (UTC)


 * 16O + 16O → 32S; 16O + 15N → 31P; 14N + 14N → 28Si; 14N + 15N → 29Si; 15N + 15N → 30Si; 17O + 16O → 33S; 17O + 17O → 34S; 16O + 18O → 34S; 18O + 18O → 36S; (there may also be reactions that yield unstable isotopes). Graeme Bartlett (talk) 03:54, 15 July 2016 (UTC)