Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

August 8

Chemical formulas (C25H35NO5)

N is a nitrogen atom, O is oxygen, every unlabelled vertex or tip you see is a carbon (which could be represented by C, but not in this style of diagram), and finally, there are hydrogens covering most of the atoms so that every C has four bonds, and every N three. (A hydrogens on O is drawn explicitly as OH when applicable) Rings with apparent double bonds are actually aromatic rings. Wnt (talk) 15:18, 8 August 2018 (UTC)

Hi, I was recently given some Mebeverine to take by my doctor and was reading about it on WP. I note the Chemical formula of this drug is C25H35NO5. As I know nothing about chemistry I was just wondering, does this mean my medicine contains Nobelium? or some kind of Nitrogen/Oxygen mix? I am a complete newbie to chemistry so apologies if this seems a very elementary, or even ridiculous question to be asking. I am just trying to understand what this formula means in reality, so any, even simplistic pointers would be most appreciated. Uhooep (talk) 10:57, 8 August 2018 (UTC)

No, it does not. The symbol for Nobelium is No, not NO. The distinction between capital letters and lower case letters is VERY IMPORTANT. A two-letter symbol is always written with a capital letter first and a lower case letter second. If you see two capital letters in a row, that means two different elements. A capital letter in the formula indicates a distinct element, and the number 1 is not written if there are just one of that element in the compound. So C₂₅H₃₅NO₅ means twenty-five carbons, thirty-five hydrogens, one nitrogen, and five oxygens. Wikipedia has articles titled Symbol (chemistry) and Chemical formula if you want more information. --Jayron32 12:45, 8 August 2018 (UTC)

The diagram of this chemical in the Mebeverine (top–right of the whole article) helps illustrate the location of the one nitrogen and five oxygens (and no nobeliums). These sorts of skeletal diagrams might not be generally meaningful to lay readers, but they can help reinforce some formula details. DMacks (talk) 13:44, 8 August 2018 (UTC)

I've added this above. Wnt (talk) 15:18, 8 August 2018 (UTC)

The chemical formula tells you basically nothing about the molecule. Virtually all organic molecules are just carbon, hydrogen, oxygen, and maybe nitrogen arranged in different ways. Sometimes there's an extra element or two thrown in for variety. To know anything about how it behaves, both on its own and in vivo, you need to analyze its structure. This is why chemists use things like structural formulas. As the article states, mebeverine is an analog of papaverine. It is believed to work by antagonizing muscarinic acetylcholine receptors and probably also blocking some calcium channels in smooth muscle. It may have other targets as well—not surprising as papaverine appears similarly "dirty". --47.146.63.87 (talk) 07:05, 9 August 2018 (UTC)

The chemical formula can be informative. For example, this search brings up mebeverine as hits 2, 3, and 5. One of those is a ChemSpider hit,[1] though oddly, the #1 hit - the ChemSpider search itself doesn't link to that! Well, their computer problems aside, the formula would find you the compound you wanted, among some isomers. You can also do little tricks like say C gets 25 x 2 = 50 half bonds beyond what is needed to make a chain, plus 2 at the ends (52). Adding an N anywhere in the structure adds one more place for a hydrogen. Unless double bonded, O doesn't affect anything (C-H to C-OH needs no hydrogen). So if we take 53 half bonds pointing out from the non-hydrogen atoms and tack on 35 hydrogens, that leaves 18 half bonds unaccounted for, which have to be attributed to some kind of looping back of the structure, either double bonds or rings. And if you look, there are 7 double bonds + 2 rings! This sort of empirical formula watching is most useful for determining structure when there aren't any left over, but it is part of the deduction in any case. Wnt (talk) 14:02, 10 August 2018 (UTC)

We have a Degree of unsaturation article:) DMacks (talk) 14:14, 10 August 2018 (UTC)

Can anybody identify this insect?

Unidentified flying insect found in southern France, Gers region

It was approximately 5cm in length, and would occasionally buzz its wings. It did not actually fly whilst I was observing it, which was not for long as someone stood on it. — PhilHibbs | talk 13:47, 8 August 2018 (UTC)

Mole cricket most likely. They typically hang around in summer. Brandmeister^talk 14:15, 8 August 2018 (UTC)

Thanks, looks very like Gryllotalpa africana. — PhilHibbs | talk 14:55, 8 August 2018 (UTC)

Could also be a Jerusalem cricket. --Jayron32 14:56, 8 August 2018 (UTC)

Nah, not in the south of France (see notation under picture); besides the morphology is all wrong. Looking at the distinctive features of the head and prothorax in particular, I would say Brandmeister hit the nail on the head. Based on the aggregate clues, we seem to have two likely contenders for the exact species: the very common European Mole Cricket, Gryllotalpa gryllotalpa, and the less common (but notably also a native of southern France) Gryllotalpa vinae. The afore-mentioned Gryllotalpa africana is sometimes found in Europe, but I can find no source that reports sightings in France (they seem to be confined to rare sightings in Portugal in the West and the Caucus region and Eastward). Snow ^{let's rap} 01:42, 9 August 2018 (UTC)

August 9

Please explain this power plant availability formula specially the summation part

thermal generating station for any period means the average of the daily average declared capacities for all the days during that period expressed as a percentage of the installed capacity (in MW) of the generating station minus normative auxiliary consumption as specified in these regulations and shall be computed in accordance with the following formula; N Availability = 10000 × Σ DCi

/ {N × IC × (100 – AUXn

)} % i = 1 Where — N = Number of time blocks in the given period as may decided by the Commission from time to time; DCi

= Average Declared ex-bus Capacity in MW for the ith time block in such period;

IC = Installed Capacity of the generating station in MW; AUXn

= Normative auxiliary consumption as a percentage of gross generation;45.120.17.7 (talk) 04:22, 9 August 2018 (UTC)

Here is how I think your text should appear. The underlined parts are my guesses that could be wrong.

The availability of a thermal generating station for any period means the average of the daily average declared capacities for all the days during that period expressed as a percentage of the installed capacity (in MW) of the generating station minus normative auxiliary consumption as specified in these regulations and shall be computed in accordance with the following formula.

$Availability=$100$*\sum _{i=1}^{N}DC_{i}/(N*IC*(100-AUX_{n}))\%$

where:

$N=$ Number of time blocks in the given period as may decided by the Commission from time to time

$DC_{i}=$ Average Declared ex-bus Capacity in MW for the $i$th time block in such period

$IC=$ Installed Capacity of the generating station in MW

$AUX_{n}=$ Normative auxiliary consumption as a percentage of gross generation

(more follows)

Explanation: If $N=3$ the summation part $\sum _{i=1}^{N}DC_{i}$ would be calculated as $DC_{1}+DC_{2}+DC_{3}$. DroneB (talk) 15:43, 9 August 2018 (UTC)

It's not clear from the original whether the denominator (N*IC*AUXn) is part of the summation terms or whether it should be a denominator for the summation as a whole. What is the order of operations precedence of sigma-summation vs division? Mathematically it doesn't matter, but either way, it would be clearer (and one less level of parens) to write the fraction as a fraction:

$Availability=\sum _{i=1}^{N}{\frac {DC_{i}}{N*IC*(100-AUX_{n})}}*100\%$

or

$Availability={\frac {\sum _{i=1}^{N}DC_{i}}{N*IC*(100-AUX_{n})}}*100\%$

DMacks (talk) 17:34, 9 August 2018 (UTC)

I think the "100" is wrong (or at least the overall context is confusing) because the "100-AUXn" term in the denominator means we are in something like "1/%" units. To get to normal fractional values, we need to multiply that by 100. To get that to percent (consistent with how AUXn is), we need to multiply by 100 again. So it should be 10000 not 100.

IP, it would be useful when you ask these questions to give a link or context to where to are reading something you would like explained. I found the formula (confirming "*10000" not "*100") by googling ["power plant" availability "auxn"]. DMacks (talk) 18:09, 9 August 2018 (UTC)

Drowning

According to Drowning#Forensics, "Forensic diagnosis of drowning is considered one of the most difficult in forensic medicine", etc. This is surprising. Aren't considerable amounts of aspirated seawater or fresh water in the victims' lungs a reliable sign of drowning? Additionaly, at least seawater should leave salt traces on the victims' skin and elsewhere, corroborating the diagnosis. I remember that the first aid involves expelling the aspirated water from the victim's respiratory system. Thanks. 212.180.235.46 (talk) 16:21, 9 August 2018 (UTC)

After you have read the cited section do you know some easy way to distinguish whether the death was due to immersion, or whether the body was immersed post mortem? DroneB (talk) 17:08, 9 August 2018 (UTC)

See also Diagnostic of Drowning in Forensic Medicine; "The diagnostic of drowning is described in the literature as one of the most difficult in the field of forensic medicine... The main goal in this field is to differentiate a death by submersion from an immersion of a body. Death of a victim found in water should not always be related to drowning". Alansplodge (talk) 18:58, 9 August 2018 (UTC)

It's odd though, because as far back as old Agatha Christie's and the like—and possibly earlier—a well-known trope is that water only gets into the lungs whilst they are working; i.e., while the victim is alive. In other words, the presence of water in the lung indicates drowning and the lack of it, immersion post-mortem. H'mmm. —SerialNumber54129 ^{paranoia /cheap sh*t room} 14:20, 10 August 2018 (UTC)

The source linked above and Drowning: Still a difficult autopsy diagnosis both consider testing to determine if diatoms found in the water in the lungs have passed into the circulatory system, which would indicate drowning. This seems to contradict Christie's hypothesis. Alansplodge (talk) 12:08, 12 August 2018 (UTC)

August 11

Consequence of the ideal gas law?

Could one say (using some sources if really needed) that the Nernst equation is a (logical) consequence of the ideal gas law, that can be easily deduced?--213.233.84.55 (talk) 15:59, 11 August 2018 (UTC)

Nernst equation resembles the equation for the Gibbs energy for ideal gas but I doubt that you can logically derive the former from the latter. Ruslik_Zero 20:28, 11 August 2018 (UTC)

No, neither is the consequence of the other, the best way to think of them is that they are both consequences of statistical thermodynamics, i.e. the connection between temperature and energy. You may have noticed that "R" (the universal gas constant) appears in both equations. R itself is not really a fundamental constant, it is derived from the Boltzmann constant (k), which is simply the relationship between temperature and energy; any time you'll be taking a temperature measurement and using it to calculate an energy, the Boltzmann constant is the conversion factor between what you can measure (temperature) and an abstract concept you can never directly measure (energy). You use "k" (the Boltmann constant) when you want energy per particle and you use "R" (the universal gas constant) when you want the energy per mole of particles. The quantity nRT has units of energy, as does the quantity PV, so that's the ideal gas equation. In the Nernst equation, you need units of volts, and a volt is a Joule per Coulomb (a volt is the motive force a mole of electrons has, Joule is energy, and a Coulomb is the charge carried by a mole of electrons). That's where the R comes into play there; the RT/zF gives you the unit of volts, which you need to add/subtract from the standard cell voltage based on how far off from equilibrium (the Q) your actual cell is. Just remember any calculation where the fundamental principal is based on energy, but you can only measure temperature, will have R show up somewhere. --Jayron32 21:19, 11 August 2018 (UTC)

weather averages

Why, in Los Angeles, is August (2 months after the solstice) the hottest average month, while December (the month of the solstice) the coolest average month (https://wxch.nl/2ntZXP2)?

According to these tables, in LA July ist just as hot as August and Januar and Februar are both cooler than December: https://www.holiday-weather.com/los_angeles/averages/ 194.174.76.21 (talk) 12:09, 15 August 2018 (UTC) Marco Pagliero Berlin

It's all to do with temperature lag which varies from place to place. June was certainly hottest where I live. Dbfirs 16:33, 11 August 2018 (UTC)

"Monsoon": ~90° change of direction

There is also a seasonal change in the direction of the weather pattern in the Southwest that begins typically 2nd week of July and lasts about 6 weeks -- known as "monsoon season" where I come from. Although it primarily affects AZ & NM, it might presumably alter weather in CA to some degree°. Unsigned post, not by Akld_guy. -- OOPS! That would be me → 107.15.157.44 (talk) 09:53, 12 August 2018 (UTC) ... Wonder why auto-sign-bot didn't catch that

Allowing for the different hemisphere, the same thing happens here in Auckland, New Zealand. The weather warms up in October and November as we come out of winter, then about mid-December it goes noticeably cooler. Usually there is cold, stormy weather around New Years, including snowfalls in the mountains 150 miles south of here, and we might have to put on our coats for a few days. This is not what you'd expect in mid-summer. Then, the hottest part of the year follows from mid-January to mid-February. Why? My WP:OR reasoning is that Auckland is at a certain latitude where the sun passes overhead and actually goes south (think north in your hemisphere) around the solstice. Thus, there are two warm peaks, the first as the sun is rising higher and higher in October-November, then a cooling as it goes south, and finally a reheat during January-February as it passes overhead again on its way north. Confirmation might be implied by the fact that Christchurch, far to the south of me, gets one summer peak, not two, which is centered on the solstice. Los Angeles and Auckland are both harbour cities, which may mean a more rapid cooling between the two peaks than in inland cities. Akld guy (talk) 05:34, 12 August 2018 (UTC)

Element/Fire Stryker fire extinguisher

This product caught my eye. At first I thought that the Element and the Fire Stryker were the same product, but the following YouTube videos show wildly different performance -- and no manufacturer tells a fib on a YouTube demo video, right? :(

• https://www.youtube.com/watch?v=oBjXecsF860

• https://elementfire.com/

• http://www.desert-wolf.com/dw/products/fire-and-rescue/fire-extinguishers/fire-stryker-portable.html

• https://www.youtube.com/watch?v=PI-LWv0vH2k

• https://www.youtube.com/watch?v=GwzZJInS40g

The other thing I noticed was that Element seems to be really vague on the topic of what chemical they use.

Does anyone have any information on this technology? --Guy Macon (talk) 22:17, 11 August 2018 (UTC)

August 12

Feynman Lectures. Exercises. Exercise 27-2 PNG

...

27-2. A certain beam of light is converging toward a focus at a certain point P. It is desired to insert a single reflecting surface passing through a given axial point Q which will reimage the light to a new point focus at a given point P'. Find the shape of the required surface. Let the distance QP' = D and QP = d.

—  R. B. Leighton , Feynman Lectures on Physics. Exercises

The Solutions give an answer that according the Fig. 26–11 the surface is an ellipse. But I think that a plane mirror between P and P' is also acceptable according to image. Is it correct? Username160611000000 (talk) 07:09, 12 August 2018 (UTC)

Only for specific values of P' and Q. Given the system in the image, for any arbitrary point Q to the right of P and P' to the left of Q, you can design an elliptical mirror containing the point Q and having P and P' as its foci. (That obviously goes tits-up if Q is to the left of P', and less obviously if Q is between P' and P.) --Link ^(t•c•m) 10:40, 12 August 2018 (UTC)

Aiming for planets

When Apollo craft were coming back from Moon, were the modules aimed akin to firing a bullet onto a moving target (i.e., slightly in front of the target's actual position in order to account for passage of time), or does the Earth never seem to move... which it does, some tens of thousands of kilometers per second on its yearly journey around the Sun? 46.188.151.206 (talk) 10:19, 12 August 2018 (UTC)

The Moon moves with the Earth, so aslong as you are only going to the Moon (and back to Earth), then a geocentric model should suffice. LongHairedFop (talk) 12:08, 12 August 2018 (UTC)

'Thus it was not surprising that one of the first contracts NASA let for Apollo was for the guidance and navigation system for the journey... The system was primarily inertial, but to correct for drift, it would carry “…a space sextant to make periodic navigation angle measurements between pairs of celestial objects: the sun, the near planets, and selected stars..”'. See US Institute of Navigation - Sextant, Apollo Guidance and Navigation System. Alansplodge (talk) 12:15, 12 August 2018 (UTC)

The Earth and Moon orbit around their common center of mass (which is close to the Earth's center) and the Earth+Moon combined mass is in orbit around the Sun. The Apollo capsule was always part of that combined mass. The article Trans-lunar injection describes the transfer of a mass such as the capsule with its contents from the Earth to the Moon. The velocity of orbiting the Sun does not enter the calculation because it is unchanged for Earth, Moon and capsule. The burn maneuver differs from that of a bullet which receives only a one-time explosive thrust. The Apollo missions (see Apollo 11) required separate stages of self-propelled controlled rocket propulsion to achieve these targets: inital low Earth orbit, initiate trans-lunar maneuver, enter lunar orbit and lunar descent. The initial rocket stage was discarded after burn and flew into orbit around the Sun. DroneB (talk) 12:38, 12 August 2018 (UTC)

• Neither. The path was within the gravitational influence of the Earth-Moon system, and journeys in space are done by coasting to save fuel. So this path was (inevitably) going to be an orbit, or partial one. The idea of "aiming" is more like orbital injection into the correct (and in this case, trans-lunar) orbit, less like lead in aiming (where the aim has to be offset for a moving target, but the projectile isn't then influenced by the gravity of the target).

It's also difficult to calculate this. So it was done in advance on Earth (it couldn't even be done easily on demand on Earth, as computation wasn't fast enough). The "aiming" from the Apollo vehicle was a question of being tracked accurately by an Earth station, the necessary corrections worked out, then Apollo told to orient themselves on a particular bearing (using the on-board sextant) and firing the engine for an Earth-calculated period. Despite the difficulty of this, Apollo 11 was scheduled for something like four in-course correction burns, but its track was so accurate that they only needed to fire two of them. Andy Dingley (talk) 16:52, 12 August 2018 (UTC)

The general case of this: Three-body problem § Restricted three-body problem. Yes, essentially, the Earth "never seem[s] to move" in your frame of reference. You're launching from Earth. Earth is moving around the Sun, but so are you, on the same trajectory. Since you don't care about going to the Sun or some other planet, you only need to calculate your trajectory with respect to the Earth-Moon system. --47.146.63.87 (talk) 02:09, 13 August 2018 (UTC)

Black or white?

Given a house under the sun and you sprinkle water on the exterior walls.

Would it be cooler inside, if the walls are painted white or painted black?

I assume that dry white walls would keep the interior cooler. However, I wonder whether a wet black wall would evaporate more water, hence reducing more the temperature inside.--Doroletho (talk) 14:19, 12 August 2018 (UTC)

India decreased heat-related deaths by painting roofs white. Los Angeles has been painting some roads a light gray to decrease temperatures.

From my own experience, you're always better off drinking the water. Ian.thomson (talk) 14:25, 12 August 2018 (UTC)

Yes, I don't doubt that white or light grey decreases temperature. And I don't believe using water would be an efficient way of cooling down a house, especially not in India or California, which seem to have water shortage. I just want to know the physics behind it.--Doroletho (talk) 14:43, 12 August 2018 (UTC)

You might be surprised. Evaporative cooling systems are fairly widespread in areas meeting the right criteria: high air temperatures, low relative humidity, reasonable access to water. Our article has a number of details. (And if you're interested, it's pretty easy to find HVAC companies that will be happy to sell you an evaporative cooler in California.) Note that while evaporative cooling will increase an individual household's water usage, it also decreases that household's electricity usage—and since there is a remarkable amount of 'hidden' water usage involved in electricity generation, evaporative cooling can result in a net reduction in water usage overall. TenOfAllTrades(talk) 15:57, 12 August 2018 (UTC)

With a black wall, more water would evaporate, but only because the wall gets warmer. A warmer wall means a warmer interior. In other words, the black wall increases cooling by evaporation, but not enough to compensate for the increased heating by absorbsion of light. Now, you could design a clever cooling system that's powered by solar heat. PiusImpavidus (talk) 15:13, 12 August 2018 (UTC)

That exists. Cooling is a byproduct of water production. In hot/dry places, there is still water in the air - just not much. So, use a black box to absorb heat and make it very hot inside the box. Now, run coolant from outside box into coils inside the box. While the coolant is actually hot, the box is hotter. So, water will condense on the coils and drip off (filter it for drinking water). Then, run the coolant through the walls of a building to cool it down. Then, back up to the evaporator box. Use solar panels to run the pump. You can build one easily, but it won't be very efficient. Science fair models I've seen are lucky to get a gallon of water a day and cool by a few degrees. An industrial installation I inspected in New Mexico pulled out 8-15 gallons of water a day (depending on humidity and heat) and cooled a 4-bedroom house by up to 10 degrees. They were able to leave AC off all day while at work and school, having it turn on shortly before they returned home. 209.149.113.5 (talk) 13:12, 13 August 2018 (UTC)

Decreasing light pollution as night progresses

I'm thinking since more people turn their lights off and more places get closed as night progresses, logic tell us that resulting light pollution would decrease therefore darkening the skies as it gets later in the night. For example, there will be less light pollution at 3am than at 10pm albeit by a slight margin. Honoring peak Perseid meteor activity tonight, I'm asking you if my thought is true so it can show people when it is the better time to watch for meteors for those who live in light-polluted cities or towns. PlanetStar 18:04, 12 August 2018 (UTC)

I could never tell in my city but people turning their lights off hardly matters when there's like 1500 streetlights per square mile and rent is so high compared to the cost of electricity that closed businesses leave a lot of brightly lit signs on. The higher the percent of light pollution not coming from light that turns of while it's still dark the lower the artificial light maximum vs minimum ratio. At any rate most meteor showers are best seen at the start of morning astronomical twilight, when you're looking through Earth's windshield instead of Earth's rear window but it's not dawn yet. In extreme light pollution the best time might be around to the start of morning nautical twilight. Cause in a not especially hazy or clear summer night without bright lights in my eyes I could barely see the twilight at the bright edge of astronomical twilight, the extreme light pollution overwhelms it. Sagittarian Milky Way (talk) 19:08, 12 August 2018 (UTC)

The University of Vienna monitors sky brightness, the measurements are here. Leave the location at "SQM-LE @ IFA" (that's within Vienna) and look at a few nights. "09.08.2018-10.08.2018" shows the behaviour proposed by PlanetStar; that was a clear, moonless nights (except, apparently, for a bunch of clouds moving through at around 1:30am). Other nights are less clear-cut. The moon clearly increases sky brightness, clouds do so much more, and also cause strong fluctuations in the measurements, which makes many nights harder to interpret). The city of Vienna switches off every other street lamp at 11pm (mainly to save energy and money rather than to fight light pollution); I think the effect can be seen here. --Wrongfilter (talk) 20:04, 12 August 2018 (UTC)

That's pretty neat. Unfortunately that number of magnitudes is not that noticeable to the naked eye (it might if you view the sky at shutoff making it somewhat like a blink comparator but the actual improvement isn't that great) Maybe too many of the other municipalities in the area don't join in? If half of every light within 200-300km of Vienna turned off at 11 you might get about 0.75 magnitudes drop right? Sagittarian Milky Way (talk) 20:25, 12 August 2018 (UTC)

I just talked to the local expert. It's less than a factor of 2 because of the significant fraction of light from private households (out of windows, etc.). Also, it's not exactly half the street lighting that's switched off, more like a third or so. In a paper, they published a number of 0.18 mag/arcsec² for the 11pm curfew, and another 0.09 mag/arcsec² at midnight, when facade lighting is reduced (also just visible in the graphic I linked to). --Wrongfilter (talk) 13:19, 13 August 2018 (UTC)

If only other cities would do such a thing. Why don't they just reduce the streetlight current or voltage instead of turning some off? Turning some off would increase the ratio between dim and bright patches of street (which is one of the reasons why blasting dozens of thousands of lumens per lamp doesn't help crime (the street is so bright the mugger or burglar covers himself in black, waits in a shadow and the elderly (maybe younger) don't see him)). Also, if they reduce brightness slowly over 10 minutes or 1 hour or something it'd look less obvious and maybe they can cut more than half before the public starts complaining (of course if big enough drop people would start noticing things about the light level itself instead of just the suddeness like the private lights looking much brighter late and maybe color vision weakening (mesopic) and I don't know the politics of Vienna enough to guess at what point the public would start complaining) Sagittarian Milky Way (talk) 20:39, 13 August 2018 (UTC)

August 13

Float gauges

What does one of these things look like when it's in good condition? We have no float gauge article, and the other images in Commons:Category:Level gauges don't look like they could be contorted into this shape. A Google Images search for "float gauge" returned a mix of images of dial-shaped displays (example) and images of glass objects (example), none of which I can imagine becoming shaped like this under any kind of pressure. NB, the image appears in Water hammer, where it's captioned "Effect of a pressure surge on a float gauge". Nyttend (talk) 00:54, 13 August 2018 (UTC)

The item in the photograph is a float gauge for an industrial application like a large fuel tank or a separating tank. (The image page has a caption that specifies this detail: this is a float gauge for a pressure-relief valve in a separator tank). Here's a diagram from the horizontal separator article at the Schlumberger Oilfield Glossary.

Of course, separating tanks occur in all kinds of other industries as well: for example, we have an article on vapor–liquid separators.

You might use these as starting points to find more complete diagrams of similar float valves in fully-intact systems.

For example, you can buy a new float valve, also suitable for use in industrial propane systems or refrigeration systems, from this catalog: (Page 70): flange plate with float valve, from ESK Schultze, esteemed distributor of high-quality schwimmerventile.

Nimur (talk) 05:17, 13 August 2018 (UTC)

It is hard to imagine how one would get water hammer inside a separating tank.

I asked the person who uploaded the picture:[2] --Guy Macon (talk) 05:34, 13 August 2018 (UTC)

You flood a closed rigid tank with an excessive flow rate inwards, which then creates a shock wave. Or you introduce a shock wave down one of its pipes (even backwards against normal flow). The fact it's a closed tank (it might even have been vented) doesn't mean that it can't have a float gauge in it. Andy Dingley (talk) 10:30, 13 August 2018 (UTC)

• It's an easily manufactured, closed, sealed volume. Typically spherical or cylindrical, they used to be made from a pair of metal pressings (or spinnings), with a seam between them, rolled, soldered or welded. For low pressures, most are now plastic and made by something like rotational moulding which can make an inherently closed volume. Andy Dingley (talk) 10:33, 13 August 2018 (UTC)

What place has the shortest average wait for sustained hurricane wind from tropical cyclones?

What about for the US? It must be somewhere in Florida or North Carolina. Worldwide, I'm guessing it's somewhere in Greater China, the Philippines or another West Pacific island. Each storm counts as one (getting 2 eyewalls and an eye doesn't count as 2) Sagittarian Milky Way (talk) 19:49, 13 August 2018 (UTC)

Let me reword your question. "We can calculate a location's average time from when it gets hit by one hurricane until it gets hit by another. Where in the world is this average time shortest?" Is this what you mean, or did I mangle it? Obviously I saw the hurricane-force winds bit, so I know you don't want to count a storm if the outer bands hit, with sub-hurricane-force winds. Nyttend (talk) 23:31, 13 August 2018 (UTC)

To reword it again, does the question not boil down to "Which places get the most frequent hurricanes?" Matt Deres (talk) 01:30, 14 August 2018 (UTC)

That question (obviously the one intended, based on next response) could be answered with "This place gets them every two years", but "shortest average wait" sounds to me like the standard deviation is low, i.e. they come at more regular intervals. Nyttend (talk) 04:06, 14 August 2018 (UTC)

Maybe I didn't think that one though. Below Philippines doesn't have much Coriolis effect, the hurricane wrecking mountains of Taiwan and the Philippines partially shield a lot of coast like Vietnam and Fujian and the Honshu elbow near Tokyo might be too north to have the record? There's also smaller islands like Okinawa and Guam that would have the benefit of not affecting circulation of approaching storms as much as the big mountainous landmasses like Taiwan (altitude: 13,000 feet) Sagittarian Milky Way (talk) 05:33, 14 August 2018 (UTC)

"Which places get hurricanes most frequently? (where hurricane is defined as getting close enough for hurricane force wind (1-minute average (some countries call them typhoons etc. and use longer averages))" Sagittarian Milky Way (talk) 03:10, 14 August 2018 (UTC)

This is becoming confusing. The first post mentioned tropical cyclones, which are a particular type of storm. In the US such events are called hurricanes. But a hurricane is also a wind speed, which can occur occur independent of a tropical cyclone. So I have no idea where this is going. HiLo48 (talk) 03:16, 14 August 2018 (UTC)

Only counting hurricane force wind caused by tropical cyclones. Sagittarian Milky Way (talk) 03:24, 14 August 2018 (UTC)

• Does This help? --Jayron32 14:10, 14 August 2018 (UTC)

Taiwan is a significantly smaller target than a lot of the rest of the list and is 7th so Taiwan is certainly a candidate. #1 Mainland China had 127 storms in that time period but is a big target so who knows if any point of the Mainland beats all points of Taiwan. I'd be happy with narrowing the point down to a length of coast or archipelago the size of Luzon or the Marianas. Sagittarian Milky Way (talk) 20:32, 14 August 2018 (UTC)

What's the last vegetable here?

The leafy green "san choi" (Cantonese, represented by a character with three dots on the left signifying water, not lettuce) [3] Thank you. 104.162.197.70 (talk) 22:06, 13 August 2018 (UTC)

I'm not getting anything from Google. The picture is not great; many leafy greens look broadly similar at a resolution like that, but if I had to hazard a guess it would be that it's baby spinach. I am less than useless at Cantonese; do any of the terms here make sense? Matt Deres (talk) 01:27, 14 August 2018 (UTC)

Possibly Basella alba also known as "Malabar Spinach, vine spinach, red vine spinach, climbing spinach, creeping spinach, buffalo spinach and Ceylon spinach". See [4] figure 9. Our article says "潺菜, 木耳菜, 落葵 or 蚕菜, being saan choy, xan choy, shan tsoi, luo kai, shu chieh, and lo kwai in some of readings of Cantonese". Nil Einne (talk) 04:29, 14 August 2018 (UTC)

BTW same answer is suggested here for a similar sounding vegetable [5] although I guess we already have what wikipedia says anyway. See also [6] which has an image of the vegetable removed from the plant. (And also the same names etc.) Nil Einne (talk) 04:51, 14 August 2018 (UTC)

August 14

Glyphosate use by country

I cannot find a map or anything. Thank you for any help you can offer. Anna Frodesiak (talk) 21:45, 14 August 2018 (UTC)

I don't see that anyone has made such a map. The closest I can get to answer you is to point you toward [7]. They have some very extensive data there on farming and pesticide/herbicide use by country by year. You can click on "pesticide use" for instance, and look up all of the data on pesticide/herbicide use in all countries with available data in a certain year. Unfortunately they don't break the categories down to individual chemicals, just to classes of chemicals. You would also of course want to normalize data by amount of farmland, or total agricultural output or something. Which you should also be able to find on that website. Someguy1221 (talk) 22:31, 14 August 2018 (UTC)

Thanks for that link.

I found this too.

It would be great if we could get a map image together for the articles. Do you think that is possible? Anna Frodesiak (talk) 23:26, 14 August 2018 (UTC)

It would be nice - there is certainly a lot of great data in there. But searching the site, I can't find anything like that level of detail for glyphosate. I even looked in the raw data, it's not there. It's just bundled into "herbicides". Someguy1221 (talk) 23:49, 14 August 2018 (UTC)

Since Monsantos patent expired in the year 2000, Glyphosate is contained in over 100 products of different brands. Also you have to keep in mind that these Products are, like the original "Roundup"-Product from Mondsanto, always Mixtures of up to 30 or more different Toxic Agents - often changed over time and on top kept disclosed as business secret, with only Glyphosate mentioned like a "quality guarantee". So it would not only be some huge work to sum up all the different Brands market share but also likely impossible to sum up individual Toxic Agents to a total physical volume or weight used in some region or country, especially in socalled free market economies with little or non regulation and oversight. --Kharon (talk) 00:52, 15 August 2018 (UTC)

Beyond the data already linked, there is an estimate for US and global usage of glycophosphate until 2014 here [8]. Although the US has not issued one report since 2007 (per the above source), it's clear that the US data comes largely from US government sources. I suspect getting accurate data is actually a far bigger problem in developing countries like India or Brazil than in developed ones even those generally recognised as having freer markets, despite Kharon's suggestions to the contrary. (Compare for example their relatives levels on the Index of Economic Freedom or Economic Freedom of the World). Nil Einne (talk) 09:04, 15 August 2018 (UTC)

Alastor angulicollis

Hello, everyone! We have that article there but, unfortunately, no image... There also seems to be no proper image on Google at all! Can anybody provide assistance with finding a picture of this species?--Neufund (talk) 22:58, 14 August 2018 (UTC)

oh, this is super obscure. The only mentions of Alastor angulicollis in scientific literature are the two publications where it was independently identified, and then in two lists of species. Some modern databases also list this as Hypalastoroides angulicollis, and treat Hypalastoroides as a genus (and Wikipedia even has an article on Hypalastoroides. But one species directory places Hypalastoroides as a sub-sub-genus inside of Alastor. Anyway, I can't figure this out! The Smithsonian apparently has a pinned specimen, but no pictures of it. Someguy1221 (talk) 23:26, 14 August 2018 (UTC)

August 15

Capacities of Chemours titanium dioxide plants

Hi,

I'm looking for the capacities of the Chemours titanium dioxide plants:

• DeLisle, MS
• New Johnsonville, TN
• Altamira, Mexico
• Kuan Yin, Taiwan

The newest document I could find was from EPA (2001): Link (page 4).

Do you anything more recent? Or is here any expert on this topic?

Thanks, White Dowes (talk) 00:53, 15 August 2018 (UTC)

Existence of drug 'Mideral'

Hi all,

I was reading a novel ('The Hades Factor' by Robert Ludlum and Gayle Lynds) and Mideral was mentioned alongside Adderall, Ritalin, and Cylert, as a drug which functions as a central nervous system stimulant. However, although I know the other three exist, I can find no trace of Mideral, and was wondering whether it was fictional?

Thank you all for your help! 144.32.240.169 (talk) 08:40, 15 August 2018 (UTC)