Wikipedia:Reference desk/Archives/Science/2017 June 22

= June 22 =

anal sex & hygiene
a. What measures (or cleaning routine) are taken to keep the rectal region clean ? How sexually engaged couple makes sure that there are no remaining excretions behind ? Is an enema required each time they commence love-making ? b. Is the issue of remainings age dependent ? Namely, natural cleaning processes are more efficient when we're younger ? c. A few years ago, as I remember, I saw somewhere in Wikipedia (through 'external' or 'see also' ?) some guide regarding this issue, medically & hygienically. Any ellaboration is welcome. בנצי (talk) 15:07, 22 June 2017 (UTC)
 * Here's a guide from Cosmo, here's one from Men's Health . Dan Savage also has plenty to say on the topic, see e.g. here or search The Stranger archives for related content. SemanticMantis (talk) 15:13, 22 June 2017 (UTC)
 * Also see under point 3 in this Article in the cosmopolitan. Seems google thinks cosmopolitan-readers practice this allot :D. Doubtfull if "amateurs" always take as much care and you can be shure todays media would reveal if both ever did any seriouse harm to anyone - i remember reading about people needing surgery after "working" themselves up with big objects in that area so anything alike oddly ironic would have made headlines too. I also read there are far worse (medically & hygienically) frequently practiced kinks in human sexuality. --Kharon (talk) 17:15, 22 June 2017 (UTC)

The Wikipedia article about Anal sex has general information but it is not a how-to guide. However it links to an external guide that concludes "The most important pieces of advice anyone can give on anal sex are: lubricants, condoms, and patience." Blooteuth (talk) 07:56, 23 June 2017 (UTC)
 * There are a lot of things I've seen written about this topic that don't seem to add up. For example, I have no idea how the logistics of prison rape are supposed to work when it is done this way (and certainly I've seen sources that say it is).  Are the victims forced to prepare in advance, or do the guards see one guy crying with a soiled uniform in the rear, and another with a soiled uniform in front, and just smile and keep going about a good day at work?  And there are authors like Norman Mailer who seem to engage in flights of fancy, or at least, fantasies that omit anything unappealing. Wnt (talk) 11:57, 23 June 2017 (UTC)
 * Preparing is not mandatory at all, and I confirm it does not get messy very often, even without any preparing. But many people like to prepare. Here is a very detailed description with drawings of how to thoroughly prepare (not safe for work) :  --Lgriot (talk) 15:50, 23 June 2017 (UTC)
 * I should add I think the Norman Mailer thing I was thinking of was Armies of the Night, where a guy pretty much forces a woman (I mean, 1960s standards of consent...) to put up with a series of thrusts alternately to anus and vagina, which he uses as a ... literary metaphor.  I remember thinking that actually, no, your girlfriend would not get an unpleasant (not really) "yeast" infection from that, because by the time it affected her ... she wouldn't be your girlfriend anymore.  The part that stretches my belief is the assumption that it is OK to just spring anal sex on someone and expect to get away clean. Wnt (talk) 16:30, 25 June 2017 (UTC)

Free Neutrons making dark matter
I have a doubt. Please clear it. Can neutrons interact with electromagnetic radiation or electromagnetic fields? I am thinking that as neutrons have no net charge, they don't interact (I may be wrong). So I have a thought that free neutrons (like a diffuse gas) may contribute to majority of dark matter. (The reason for my doubt is that neutron stars can produce radio waves). So my major question is that can slow and diffuse free neutrons interact with electromagnetism considerably? Please help me.--G.Kiruthikan (talk) 17:51, 22 June 2017 (UTC)

The origin of this doubt : Majority of normal matter is Hydrogen. Hydrogen's majority don't have neutrons. If neutrons were produced in roughly same number as protons, I think the rest of the neutrons could not make a nucleus and may be diffuse forming the dark matter.--G.Kiruthikan (talk) 17:58, 22 June 2017 (UTC)


 * Neutrons are not elementary particles. The net charge is practically zero, but it is made up of charged particles. It does interact with electromagnetic fields. A simple experiment shows this. Shoot a beam of neutrons through a strong electromagnetic field and it will separate into two beams. 209.149.113.5 (talk) 18:34, 22 June 2017 (UTC)
 * Neutrons are not stable. With the half life of ~882 seconds they would decay very fast emitting in process copious amounts of energetic electrons. Ruslik_ Zero 19:59, 22 June 2017 (UTC)
 * The charge on a neutron is zero within the limits of experimental accuracy, so it is not affected at all by an electric field. The magnetic component of an electromagnetic field is what affects the path of the neutron.    D b f i r s   20:05, 22 June 2017 (UTC)
 * Some of the above might be confusing, so I should emphasize that as far as I know nobody expects to see any small amounts of charge on a particle - it is believed that all free particles have multiples of the elementary charge and quarks have multiples of 1/3 that amount. The charge does not vary with reference frame like other parameters in special relativity, so you can't get partial charges at a point in space by shooting things past each other either.  I have no idea what kind of awesome mathematics can be invoked to explain that quantization, but I think no one expects to find a fractional charge on a neutron if they look really hard. Wnt (talk) 20:21, 22 June 2017 (UTC)
 * Neutrons and protons were indeed formed in similar quantities at the Big Bang, but most of the neutrons all quickly got mopped up by Big Bang nucleosynthesis into helium-4; the unlucky ones that didn't decayed away. Double sharp (talk) 23:42, 22 June 2017 (UTC)
 * Only neutrons traveling at super relativistic speeds could survive for a long time. But even these will be turning into high energy protons and electrons that would be easily detectable.  However it is quite easy to make dark matter from matter contains neutrons.  If there were many free floating Earth or moon like objects floating between the stars they would be dark.  However these might be detected by gravitational lensing or eclipsing stars. Graeme Bartlett (talk) 08:56, 23 June 2017 (UTC)

Why is this seal used on buzzers ?
Why do we need to remove this seal after washing etc.[] 124.253.253.172 (talk) 19:27, 22 June 2017 (UTC)


 * This seal is there to cover the hole that is underneath. When a PCB has been assembled the soldering flux is washed off and the seal prevents this fluid from getting into the hole and damaging the buzzer. The seal also mutes the loudness, which in some applications may be desirable. The innards of these devises are also affected by moister etc., and thus its life can be prolonged by leaving the seal in place (at the expense that it operates more quietly).  Also note, the circle with the + sign within it, aids quick identification of the positive terminal;  although this should be obvious from the length  of the leads. Aspro (talk) 22:28, 22 June 2017 (UTC)


 * Whoops... Completely missed answering your question. One does not need to remove it. The manufacturer of the buzzer leaves the choice to its customers – but only after  washing. Aspro (talk) 23:00, 22 June 2017 (UTC)