Wikipedia:Reference desk/Archives/Science/2014 August 15

= August 15 =

Candida Fungus
I just want to know if a Candida Fungus in men (systemic or Prostate) can cause anejaculation.

Thanks, Jeffrey van Vogt — Preceding unsigned comment added by 64.201.178.145 (talk) 09:55, 15 August 2014 (UTC)


 * You mean in the absence of any sexual activity ? StuRat (talk) 17:28, 15 August 2014 (UTC)


 * Just to confirm - you do mean anejaculation (inability to ejaculate), not "an ejaculation" (that is, spermatorrhea)? Tevildo (talk) 19:05, 15 August 2014 (UTC)


 * Thanks, Tevildo. I was worried what candida might do to women if it caused an ejaculation in men. μηδείς (talk) 01:24, 16 August 2014 (UTC)


 * Maybe the OP should ask Tony Orlando. ←Baseball Bugs What's up, Doc? carrots→ 21:24, 16 August 2014 (UTC)


 * I'm trying to understand that comment, but it's meaning hasn't dawned on me yet. StuRat (talk) 01:28, 17 August 2014 (UTC)
 * Candida (song). Deor (talk) 09:57, 17 August 2014 (UTC)

Light scattering
When a laser shines through a mist or some similar fog, the light scatters and you can see the beam. Is there any other way to make this happen without some visible thing to shine the light through? For example, does any sort of invisible gas cause a lot of light scattering? What if the air is heavily charged? What if the air is simply very cold and nearly foggy? — Preceding unsigned comment added by 209.149.115.166 (talk) 20:20, 15 August 2014 (UTC)
 * You need some large particles of some sort to scatter the light in some way. See Tyndall effect for an explanation in liquids/solids/gels and the like, but basically, if it doesn't scatter the light in the room, it's not going to scatter the laser.  The laser, because of its intensity, may make the particles more noticeable, but ultimately there is no substance that will look in incoherent room light to be perfectly clean and without any particulate matter, and then suddenly show particulates when coherent laser light strikes it.  -- Jayron  32  20:23, 15 August 2014 (UTC)
 * Not quite scattering, but how about tuning the laser to match an absorption of a colorless gas itself? The excited gas re-emits energy in all directions (including "off to the side", where a viewer would stand) rather than in the incident direction. Seems like it would be hard to find a gas that is "colorless" to absorb a visible laser:) But since emission would typically be at a lower frequency, you could have a UV laser and "colorless in the visible range" gas. Optical pumping of gases by lasers is a known technique. Or I guess if you have a really powerful laser and really good eyes, you could consider something based on Raman spectroscopy and/or Rayleigh scattering. Hmm...sounds like that's the reason the sky (composed of colorless gas) is blue when illuminated by certain light sources... DMacks (talk) 08:37, 16 August 2014 (UTC)
 * I would have expected that the visible beams are similar to crepuscular rays of sunlight. Unfortunately that article doesn't have much science in it, but yeah, I thought those were caused by scattering off atmospheric dust. 50.0.205.237 (talk) 17:40, 17 August 2014 (UTC)
 * Particles definitely don't have to be optically resolvable (ie. 'visible') in order to scatter light. Works perfectly well for polymers, where the individual macromolecules are on the order of nanometers in size. Under ambient light, most dilute (or semi-dilute) polymer solutions are entirely transparent, but if you shine laser light (even a laser pointer usually has a long enough coherence length for this to work) you'll illuminate the beam, since each chain scatters. With a big enough refractive index mismatch and/or a high enough MW polymer, you'll get quite a lot of scattered light.  Condensed version : If particles (in this specific case, water droplets) are large enough in size or in number, they can scatter light even if they're too small to "see" by eye. (+)H3N-Protein\Chemist-CO2(-) 02:06, 18 August 2014 (UTC)

Margaret Mead in Lake Papakeechie
Hi,

I was wondering how long Margaret Mead stayed at Lake Papakeechie in Indiana.

Thank you — Preceding unsigned comment added by 50.102.168.252 (talk) 21:45, 15 August 2014 (UTC)
 * According to this contemporary newspaper article, she visited one Katharine Rothenberger "over the week end" [sic], presumably the weekend 7 - 9 July 1922. (This assumes "Miss Margaret Mead of Philadelphia, PA" is _the_ Margaret Mead, which is by no means certain).  Tevildo (talk) 22:41, 15 August 2014 (UTC)