Wikipedia:Reference desk/Archives/Science/2013 August 26

= August 26 =

Which source is more trustworthy on masturbation?
The following two websites seem to contradict each other.

Source: http://www.babymed.com/getting-pregnant/male-masturbation-fertility-sperm-count

The first source suggests that masturbation decreases a man's fertility, because it advises that a man should conserve the ejaculations for intercourse in order to maintain a higher sperm count.

Source: http://www.mayoclinic.com/health/male-masturbation/AN01189

The second source suggests that masturbation has no effect on a man's fertility or sperm count.The two sources contradict each other, because masturbation can't affect and not affect the fertility at the same time. It has got to be one or the other, not both. Though, it may also be both but under different conditions. Sneazy (talk) 04:08, 26 August 2013 (UTC)
 * I don't think there is a contradiction. I believe the 1st source would be referring to immediate sperm count, where as the 2nd is referring to long term sperm count "in general". For example, someone who masturbates 5 times a week will not have a sperm count higer or lower then someone who doesn't masturbate at all. However, if you masturbate the day of your sperm count test then your sperm count will obviously be lower then someone who hasn't ejaculated at all in the last few days. In fact, I recently had some personal experience in precisely this regard and can tell you that the recommnedation is to not ejaculate at least three days before your sperm count test as this will provide an "optimal sample" for testing. So, I guess what it is saying is that it's possible that masturbating right before you have sex or even up to a day before could affect your fertility, but NOT that masturbating in general will affect your sperm count. Vespine (talk) 05:47, 26 August 2013 (UTC)
 * If it's not obvious, I'll add that sperm is produced in the testes at a rate far slower then most young males can expel it. It's is held in reserve in the epididymis until it is "required", but if it is ejaculated more then once every day or two you will be firing less then a full magazine, simply because you have not given enough time for the reserves to refill. In fact, the 1st source is less accurate because it is not masturbation that lowers the sperm count, it's the ejaculation, so even if you had intercourse with your mistress before having intercourse with your wife, your sperm count would be just as low on the 2nd occasion as if you masturbated. Vespine (talk) 05:58, 26 August 2013 (UTC)
 * It's worth saying that while having sex more than once within about 3 days (either with a female or solo - it doesn't matter which) will lower your sperm count - it'll never lower it to zero - so this is not an effective birth control mechanism! It's interesting to note that 18-29 year olds have sex an average of 112 times per year - which is the exact perfect rate for the full recharge of sperm.  It seems that we've evolved a sex drive that closely matches our productivity.  SteveBaker (talk) 12:58, 26 August 2013 (UTC)

...(either with a female or solo - it doesn't matter which). Does it matter if it's two males? CambridgeBayWeather (talk) 04:01, 27 August 2013 (UTC)
 * Good point - of course not. No matter how the semen gets out of the body - it's got to be replenished. SteveBaker (talk) 13:10, 27 August 2013 (UTC)
 * Hot Damn! Who was the stud machine going at it every 39 hours to balance out my celibacy? {The poster formerly known as 87.81.230.195} 90.213.246.168 (talk) 16:38, 26 August 2013 (UTC)

Boric acid
What is the pKa1 for the deprotonation of boric acid? Yes, I know what I'm asking - I'm aware of the dominant hydrolysis reaction taking place under aqueous conditions. Plasmic Physics (talk) 07:53, 26 August 2013 (UTC)

What is the equilibrium constant for:
 * B(OH)3 (s) + H2O (l) [B(OH)3H2O] (aq) ? Plasmic Physics (talk) 08:01, 26 August 2013 (UTC)


 * Found a likely ref but don't have time to check it until later today... DMacks (talk) 22:05, 27 August 2013 (UTC)


 * Thank you, I've used it correct the Boric acid article. It used the pKa1 for the tetrahydroxyborate pK value. Plasmic Physics (talk) 03:24, 28 August 2013 (UTC)

Line on globe
On an old (ca 1915) globe, there is a great circle marked with a double line. It crosses the equator at 18°W and at 162°E, at an angle corresponding to the Earth's axial tilt, and is tangent to the tropics at 72°E (in India) and at 108°W (in the South Pacific). What might be the purpose of this line? 85.226.204.42 (talk) 08:53, 26 August 2013 (UTC)


 * Is it just marking the ecliptic plane? See pictures there, and at axial tilt. SemanticMantis (talk) 13:22, 26 August 2013 (UTC)


 * That's not possible, the ecliptic plane shifts with respect to the Earth as the Earth rotates. I think it is probably marking the apparent path of the first point of Aries, which is commonly used as the reference for celestial navigation.  I could be wrong about that, but at any rate it's the path of some specific star or constellation. Looie496 (talk) 04:43, 27 August 2013 (UTC)


 * Sounds like a plausible explanation! Thank you very much for your help. 85.226.204.42 (talk) 10:03, 27 August 2013 (UTC)


 * That can't be it. Stars don't shift back and forth between hemispheres. It's probably the location of the ecliptic for some specific date and time. Dauto (talk) 14:24, 27 August 2013 (UTC)

Teflates
Does anyone know exactly why teflates (with ) are such great oxidizing agents (They even oxidize Kr and Xe!)? Double sharp (talk) 11:16, 26 August 2013 (UTC)
 * Because the Te-F bond is weak ("hard" anion/"soft" cation -- i.e. the bonding orbitals are way out of line energy-wise), which makes it energetically favorable for the fluorine atoms to go somewhere else -- even onto a noble gas atom. FWIW 24.23.196.85 (talk) 21:52, 27 August 2013 (UTC)
 * But it does appear from Krypton that the teflate anion stays together and just forms noble gas teflates... Double sharp (talk) 15:13, 31 August 2013 (UTC)

Extensively drug-resistant bacteria
It seems that there's more and more news about bacterial diseases that are resistant to (almost) all available antibiotics. Are we doomed? Will there always be new antibiotics waiting to be discovered that can treat bacterial diseases, no matter how much the bacteria evolve? It seems that the odds are stacked against humans in this fight, because to be useful any new antibiotics not only need to kill bacteria, they also need to be safe for humans. Will we run out of safe compounds to try? --173.49.10.42 (talk) 11:50, 26 August 2013 (UTC)


 * Well, in a race between the evolution of bacterial resistance and human ingenuity, I'd back the latter every time. However, in many cases (such as in the over-use and mis-use of antibiotics) it's a race between evolution aided by human stupidity and human ingenuity - and that's not such an obvious slam-dunk!


 * My suspicion (without much evidence) is that while we may be losing the battle with antibiotics like penicillin, we may have huge success with nanotechnological, phage and plasmid approaches. Our Antibiotic resistance article also talks about phage therapy which looks like a promising alternative because it pits phages against bacteria and the phages should probe able to evolve to keep up with the bacteria.


 * Early antibiotics were discovered by looking at what nature did to eliminate bacterial infections - and we came across numerous microbes that seemed to excrete substances that were able to do that. That meant that we were in a continuous chase to find new "natural" substances without really understanding how they worked.  In the modern world, we're increasingly able to examine the metabolic pathways and surface coats of bacteria and to design drugs that specifically attack them.  That's an important change in tactics - and I believe that it does give us an edge here.


 * However, no matter what we do, we're going to have to get a lot smarter about how we use these drugs and not hand them out like candy as a kind of placebo treatment to patients with viral illnesses such as the common cold. We need a sharper delineation between drugs used to treat farm animals and those that we use for humans.  We need less 'leakage' of antibiotic agents between patients in places like hospitals.
 * SteveBaker (talk) 12:50, 26 August 2013 (UTC)


 * Quibble: Not what nature did to eliminate "bacterial infections".  That's the immune system.  What we copied was the chemical warfare between different species of bacteria, or between molds and bacteria, that one sort of inglamorous life used against another in the struggle over resources. --Trovatore (talk) 19:09, 26 August 2013 (UTC)


 * Agreed, and antibacterial soaps are another culprit. Just wash the germs down the drain with regular soap and water. StuRat (talk) 15:10, 26 August 2013 (UTC)


 * Although it's not entirely obvious that repeatedly washing your hands doesn't cause the evolution of bacteria that stick to your skin better and resist being washed away. Ultimately, there may not be much that can be done beyond continually switching the strategies we use to get rid of them.  Ultimately, what we need is a strategy whereby we don't kill bacteria - but instead encourage them to evolve such as to be harmless to us.  Not killing them - but finding a drug that allowed them to reproduce more easily if they don't harm us than if they do - would evolve benign bacteria and resistance to such a hypothetical drug like that would not develop.  SteveBaker (talk) 18:43, 26 August 2013 (UTC)


 * "The Borg Cube has adapted to our shield frequencies, switching to continuously changing frequencies now." StuRat (talk) 03:36, 27 August 2013 (UTC)


 * We certainly aren't doomed, because we can always temporarily stop using a given class of antibiotic. Generally speaking bacteria pay a price for drug resistance, and if it ceases to be forced on them, they rapidly evolve to lose it.  Anyway no antibiotics at all were available for most of human history, and we somehow managed to pull through. Looie496 (talk) 02:24, 27 August 2013 (UTC)
 * Yes - and drug cocktails are another approach - forcing the bacteria to be simultaneously resistant to 10 or 100 different drugs might well overwhelm its ability to support all of the extra chemical pathways needed simultaneously. SteveBaker (talk) 13:08, 27 August 2013 (UTC)

Resting heart rate below 30 bpm not unusual?
I had long thought that Indurain's resting heart rate of 28 bmp was a "one in a million" unusual heart rate for well trained athletes. However, when searching for this in the net, I found that this is apparently not the case, there are many people who claim that they are fit healthy amateur athletes who have resting heart rates below 30 bpm. But then, I have myself a resting heart rate that can range from the low 40s to the high 30s and I know quite a few people with similar heart rates, so in that respect it doesn't seem unusual for people who train a lot harder than me to have heart rates in the high 20s. Count Iblis (talk) 12:22, 26 August 2013 (UTC)
 * We cannot offer medical advice - but we do have an article about this at Athletic heart syndrome and you might also want to read Bradycardia.
 * SteveBaker (talk) 12:34, 26 August 2013 (UTC)

Graph of Force with respect to acceleration
Suppose, we have all three quantities in the equation "Force = mass x acceleration" constant. Now, if I want to plot the graph of "F" and "a", in which "F" lies on y-axis and "a" lies on x-axis. What type of graph this would be? Concepts of Physics (talk) 16:31, 26 August 2013 (UTC)
 * If mass is constant, a straight line.-- Gilderien Talk&#124;List of good deeds 16:37, 26 August 2013 (UTC)
 * If it is a straight line, then it means force as well as acceleration are increasing with the same rate. But I am asking to plot the graph when neither force nor acceleration vary, both are constant (e.g. 5N and 8m/s/s). Concepts of Physics (talk) 17:22, 26 August 2013 (UTC)


 * Than your graph has just a single point in it (boring). Dauto (talk) 17:30, 26 August 2013 (UTC)


 * You only plot a graph where one thing is varying or unknown and the some other thing is calculated from it. So if you had a constant force, you could plot a graph to show how the amount of acceleration you'd get would change as you vary the amount of mass...or if the mass is constant, you can plot a graph to show how the acceleration changes depending on the amount of force you're applying.  Basically, it's only really useful to plot a graph when you know only one of the three things.  If you know two of them - then you can calculate the third...and if you know all three then you know all that there is to know and plotting a graph is essentially meaningless - and definitely quite useless! SteveBaker (talk) 18:37, 26 August 2013 (UTC)
 * Maybe a page like this might help? Vespine (talk) 03:52, 27 August 2013 (UTC)

Alcatraz modern day sewer
A minor reason often cited as a factor in the closure of Alcatraz prison was that the raw sewage went straight into San Francisco Bay. What happens to it now? The tourist load is heavy and I wager more sewage is generated today than when the prison was operating. Tarcil (talk) 17:54, 26 August 2013 (UTC)
 * Probably there is some kind of chemical treatment these days. But think about the numbers:  At its peak, the prison had 300 inmates and about 200 staff - but the staff lived on the island, often with their families (there were 64 apartments on the island for that exact purpose) - so the total number of people on the island was probably closer to 600.  That translates to about 600x24x365 = 5.2 million people-hours of sewage produced per year.  Nowadays, there are 1.5 million people per year visiting the island - it's hard to know how long they each stay - we were there for three hours at least - so that's more like 4.5 million people-hours.  I'd bet that most visitors take the "go before you leave" approach to toilets...so the current load is probably much less than it was at the peak of the prison - and since people aren't eating or drinking much while on the island, it's probably WAY less. SteveBaker (talk) 18:11, 26 August 2013 (UTC)


 * Wastewater is held in storage tanks and shipped to the mainland. Total wastewater output is about 6000 gallons per day. Details. TenOfAllTrades(talk) 21:03, 26 August 2013 (UTC)
 * So the typical 4,100 visitors each day produce about a gallon and a half of waste water each? A toilet takes between one and two gallons to flush - so it sounds very plausible.
 * A normal person in a house produces around 50 gallons of waste water per day - so the 600 or so 24/7 occupants of the island when it was a prison could easily have produced around 30.000 gallons per day - presumably too much for the converted landing craft that currently hauls sewage to the mainland each day.
 * SteveBaker (talk) 22:56, 26 August 2013 (UTC)

About Latitude and radiation
Hi,

By the article that I've read it's seem that the amount of radiation which hit the ground in some Latitude depends in the Latitude of the place.

I ask why; the Earth's orbit radius around the sun is way more bigger than the Earth radius.

So I would expect that the change in the amount of radiation will be minor around the globe.

Another think, in the true north the radiation direction should be vertical to the ground.

So I would expect that the amount of heat there will be far more less than it is(like Venus). Exx8 (talk) 22:22, 26 August 2013 (UTC)


 * You are right that the Earth's radius is small compared to radius of the orbit. And if that were the only effect, insolation would be more even around the globe. But we have axial tilt, and that means that the same radiation that strike 1m^2 at the equator is spread out over several m^2 at high latitudes. Flux is the general concept behind this. Imagine you hold a hoop in the rain, parallel to the ground. As you tilt the hoop, less and less rain falls through. SemanticMantis (talk) 22:30, 26 August 2013 (UTC)


 * But we would still have the same effect if the Earth had no axial tilt. In that case the solar radiation at the poles would still be less because the Sun's radiation hits at a shallow angle there, instead of straight on, as at the equator.  Also, at the poles the Sun's radiation must travel through far more atmosphere before reaching the ground, which reduces some forms of radiation.  However, the Earth's magnetic field does direct highly charged particles towards the poles. StuRat (talk) 07:39, 27 August 2013 (UTC)
 * Yes, you're right, on a given day, insolation would still drop off with latitude if there were no axial tilt. But it would be a slightly different pattern, and there would be no seasonal variation. I do think insolation would be "more even" without the tilt, but I don't have a ref for that :) I suppose flux is the most important part for the OP to focus on. SemanticMantis (talk) 14:35, 27 August 2013 (UTC)