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June 11

When were calculators minaturizable to the size of a stack of several credit cards? When did those get cheap?

I've seen a plastic 1990s calculator like that that said "Credit Card Calculator" and looked affordable and I've seen an ancient LCD one barely at the memory keys level of features yet was very thick and "c. turn of the century scientific calculator production values" looking and I know the physically tiny Intel 4004 was enough for a calculator in 1971 (not a cheap one obviously) so I'm a bit confused about the miniaturization timescale. Also, how thin did ≤7.171875 square inch calculators ever get? Sagittarian Milky Way (talk) 21:33, 11 June 2018 (UTC)

Here's the Vintage Calculator website, who cite the Mostek MM5758N (circa 1969), and similar single-circuit calculator IC products, as the key enabling technologies.

The size of the final consumer-product was not actually limited by the size of the circuitry for a few more decades, when product miniaturization was taken to its extreme.

Nimur (talk) 22:25, 11 June 2018 (UTC)

• Calculator size is and was limited by display, button, and battery sizes, not IC size. Credit-card calculators used film buttons, LCD displays, and thin solar cells instead of batteries. Slightly thicker calculators could use thin batteries instead of the older bigger batteries because newer LCDs and ICs used less power. -Arch dude (talk) 04:21, 12 June 2018 (UTC)

See Calculator watch 196.213.35.147 (talk) 05:59, 12 June 2018 (UTC)

From my faint memory: mid 1970s (ca 75, 76), green LED display calculator, ca 15cm long, 8cm wide 2cm high, eight or 12 digits, limited functions (+-*/, sqrt, M+, M-): price then reached an affordable U$ 25. Scientific calculators (market leader: Texas Instruments) maybe three times as much. Quickly prices fell further, LCD replaced with LED, thinner (less than 1cm), price maybe U$ 5. Credit card format achieved before the end of the 1980s with cheap solar cells. Price something nominal, maybe U$2 for purchase of single unit. They generally were given away as advertising gimmick. Oalexander (talk) 05:39, 14 June 2018 (UTC)

June 12

Gas centrifuge connections

Reading about the Gas centrifuge which is used to separate heavier and lighter isotopes of some gas, I understand how an electric motor can spin a tall cylinder in an evacuated outer container at high speed, like a thousand revolutionsmper second or more, with magnetic bearings rather than mechanical ball bearings which would quickly fail. But the relevant articles say that each cylinder had an inlet tube and two outlet tubes. I cannot envision a gas-tight connection which connects a rapidly rotating cylinder to a fixed gas pipe. A gas tight connection for general normal use might have a rubber o ring, or metal against metal with grease to prevent gas loss. These would fail in the first second at over 1000 revs per second. Metal on metal would melt. So how is the connection achieved, in general? Edison (talk) 01:00, 12 June 2018 (UTC)

Don't envision extracting gas radially outward from a cylinder during centrifuge; think more about a centrifugal pump. The entire outflow product is then cascaded, first through a diffusion barrier, and then through multiple pump stages, to perform enrichment. Here's a diagram, and the original source is page 98 of this great history book from the Energy Department: The New World, 1939-1946. Volume I: A History of the Atomic Energy Commission. There's a great description of the pump cascade.

The really important technical details aren't published in any books I've ever seen.

Nimur (talk) 04:11, 12 June 2018 (UTC)

{{ec}} Our Zippe-type centrifuge article agrees with this being an imporant detail, noting: "The three gas lines must be concentric with the fixed axis as the outer rim is spinning very quickly, and the seal is very important." But then I can't find details of what the actual engineering solution is. Several Iraq/ISIS restricted-materials lists simply say "magnetic bearings" and they appear to be rings, but do not comment about the surface material or tolerance. DMacks (talk) 04:16, 12 June 2018 (UTC)

I don't know anything about gas centrifuges that's not written in our articles (and if I knew, I wouldn't be allowed to tell), but I do note that at a radius of 10cm and a speed of 1500 revolutions/second, the acceleration at the wall of the centrifuge is about 8900km/s². The molecular mass of uranium hexafluoride is 349u, which gives at room temperature a scale height of about a millimetre. Close to the centre of the centrifuge there's already a pretty good vacuum. Seals for extremely dilute gases may be a bit different from normal seals. PiusImpavidus (talk) 09:47, 13 June 2018 (UTC)

• The gas-tight connections aren't rotating, they just go to the (fixed) casing. The gas connections to the rotating part are more like scoops. Yes, there is some leakage, but then gas centrifuging is an equilibrium process, not an absolute separation. Andy Dingley (talk) 11:10, 13 June 2018 (UTC)

Aren't the scoops fixed by virtue of being attached to the pipes, which are fixed to the casing, running from the casing down into the rotor? So there would be a rotating seal where the pipes penetrate into the top of the rotor. But PiusImpavidus makes a good point, which in conjunction with the fact that the casing is also evacuated, maybe the seal doesn't have to be that good. DMacks (talk) 18:58, 13 June 2018 (UTC)

There's no rubbing contact. The pipes are internal to the rotor, and they don't contact it. The only contact is at the bearings and they're usually magnetically suspended (or some other complex form). There's no rotating seal because the rotors, their bearings and armature, are all entirely within the casing. Andy Dingley (talk) 23:23, 13 June 2018 (UTC)

To clarify, there's no moving gas-tight seal for the inlet and outlet lines. They are part of the stationary center post of the centrifuge assembly. (The scoops for withdrawing enriched and depleted gas are also fixed to the center post.)

There is, however, a moving interface at the gap where the spinning rotor moves around the stationary center post. While (as PiusImpavidus notes above) the pressure of gas is pretty low already near the central axis of the centrifuge, some gas can still leak out of the rotor at this gap. It is not uncommon for gas centrifuges to incorporate a molecular pump at this interface to pull escaping gas back into the rotor. (This is accomplished by the relatively simple expedient of cutting a spiral groove into one of the surfaces, producing a drag pump.) See, for example, this NRC publication, or this FAS article. TenOfAllTrades(talk) 14:06, 14 June 2018 (UTC)

Exactly. There is a seal, and it's between a rotating and a non-rotating part. It's not a tube that rotates in its middle (cut a tube, then one end rotates vs other without leaking at the cut) but instead concentric (stationary tube that penetrates through rotating panel). Perhaps Andy Dingley would be happer calling it a stuffing box rather than a rotating seal? DMacks (talk) 14:42, 14 June 2018 (UTC)

There is no seal. They're allowed to leak. This leak is small (density at the centre of the rotor is low) and it's contained overall by the casing so there's no loss. There is a loss of efficiency (there is some recirculation of enriched material to the unenriched stream), but this is pretty minor. Andy Dingley (talk) 17:34, 14 June 2018 (UTC)

For what function melanin normally found in the adrenal gland?

The function of melanin as I know is to filtrate the UV therefore it is in the skin and iris, but it is found also in the adrenal gland. For what function it is there? (and also in the eyes some people has a little quantity of it in the eyes, and it seems that it is not necessary to be there for normal function of the eyes. Isn't it?) --93.126.116.89 (talk) 18:28, 12 June 2018 (UTC)

Why do you think that melanin is present in adrenal glands? Ruslik_Zero 20:44, 12 June 2018 (UTC)

Maybe they read our article on melanin? That's supported by this ref, which says: "Melanin is also found in certain regions of the brain and adrenal gland of some mammals." which is not a great ref for stating that is exists in human adrenal glands. This is a borderline WP:RS, but states it clearly. This does not cover the human aspect, but offers some suggestions for what it's doing there (if you already have the requisite PhD in biochemistry to understand the abstract). Matt Deres (talk) 03:17, 13 June 2018 (UTC)

Eye_color#Medical_implications links to studies that show eye color is correlated with risk of certain degenerative conditions of the eye, so the melanin in the iris could be to protect from this. As for the adrenal glands, well, melanocytes are actually found in many tissues that are far removed from your skin, and it is not entirely clear why. It is now thought that melanocytes serve a role in the immune system (mentioned on the linked page), but this is still an area of active research. Someguy1221 (talk) 20:55, 12 June 2018 (UTC)

I think it's neuromelanin that's found in the adrenals. The adrenals interface with the nervous system to release epinephrine rapidly. Abductive (reasoning) 04:58, 13 June 2018 (UTC)

Relatively little seems to be known about extraepidermal melanocytes, due in substantial part to the failure of an air conditioner in Louisiana in 1960. [1] (perhaps I overstate the case, but the spontaneous emergence of the Pigmented Extraepidermal Tissues mutant and its subsequent divergence into five different lines of differently internally pigmented mice would have been a spectacular instance for understanding both cell migration and epigenetics) However, the variously pigmented nervous tissues mostly reflect a fact that catecholamines are not exceptionally stable and are prone to polymerize. Melanin is useful as a physical barrier, I think for electron transfer to the environment, and for protection against light; bananas, for example, produce a variant of it when wounded, much as insects do. In more recent evolution (perhaps a billion years or less) animals picked up the knack of converting epithelial cells into a signalling network using the sort of aromatic amino acid derivatives formerly secreted only for pigmentation. But they may still be prone to incidental pigment formation, and as with everything that happens incidentally in biology, that can become part of the normal functioning of an organism. The adrenal medulla is essentially a sympathetic ganglion that innervates the blood, hence part of the nervous system, and its use of catecholamines like dopamine, norepinephrine, and epinephrine mean this can happen. Analogous things happen in the locus coeruleus and substantia nigra ("blue spot" and "black stuff" of the brain). Something less directly analogous happens in the red nucleus with some sort of glutamic acid derivative, I think. Wnt (talk) 11:12, 15 June 2018 (UTC)

In this context (the biological significance of melanin), the works of Hercules Petrus Wassermann might be of interest: [2] [3]. --62.99.192.174 (talk) 23:02, 16 June 2018 (UTC)

One theory I heard recently is to protect stem cells from ultraviolet light. Graeme Bartlett (talk) 09:36, 17 June 2018 (UTC)

June 13

Size difference and premature birth

In mammal hybrids, if the mother's breed tends to be much smaller at birth than the father's, does this increase the risk of a premature birth? Of injury to the mother during birth? Of the offspring being malnourished due to insufficient lactation? NeonMerlin 04:50, 13 June 2018 (UTC)

Yes. Dystocia is one of the leading causes of stillbirth. DroneB (talk) 10:21, 13 June 2018 (UTC)

• As an example, you could look at hinny, a cross between a male horse and a female donkey. Our article doesn’t say much, but maybe some references there would help. Loraof (talk) 16:19, 13 June 2018 (UTC)

• That, along with mule, indicate the size of the offspring is influenced by the size of the mother. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:23, 13 June 2018 (UTC)

Lignite mines in Gujarat

Does anyone know a source for the annual production (or capacity) of the Gujarat Mineral Development Corporation lignite mines

• Panandhro
• Mata No Madh
• Umarsar
• Bhavnagar
• Rajpardi
• Tadkeshwar

Thanks in advance!--DCKH (talk) 12:12, 13 June 2018 (UTC)

No odor disinfectants

Is there any disinfectants I can use similar to lysol that I can mix with water to mop my floors or clean with that do not have an odor? I like lysol but the odor is too strong especially when mopping.--User777123 (talk) 19:54, 13 June 2018 (UTC)

If you just search Google or Amazon for "odorless disinfectant" you'll get a variety of results, though I can't personally vouch for any of them. A lot use dissolved silver as the disinfectant. Research has shown that at the appropriate concentrations, dissolved silver (usually as silver nanoparticles in a solution of water and sodium citrate) is effective as a disinfectant, but slow acting, often taking hours to fully sterilize a surface rather than minutes for harsher chemicals: [4]. Someguy1221 (talk) 23:17, 13 June 2018 (UTC)

Yes, but they won't be very useful for cleaning. The Lysol product that the OP is talking about is not just a disinfectant, it also contains solvents that loosen dirt from the surface. It won't be easy to find a powerful solvent that doesn't irritate the nasal cavity if it is inhaled. Looie496 (talk) 23:26, 13 June 2018 (UTC)

There are odorous but volatile disinfectants, which are odorless in the sense that they evaporate without leaving a smelly residue (contrary to perfumed disinfectants like Lysol). For home use I'd suggest sodium hypochlorite (or sodium percarbonate) or an acid like hydrochloric or acetic acid. Alkalis can be mixed with surfactants, acids usually cannot. I use a mixture of dishwashing detergent and sodium hypochlorite, it works great. --185.13.106.237 (talk) 23:35, 13 June 2018 (UTC)

Borax (sodium borate) is an odor-free, and readily available option, (it also has anti-fungal properties and repels ants). The Disinfectant article might be of interest. —2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 05:22, 14 June 2018 (UTC)

Or use microfibre cloth with steam cleaning: [5]. --62.99.192.174 (talk) 15:52, 16 June 2018 (UTC)

June 14

Height above ground + distance South from Arctic Circle = Midnight Sun

Mt Denali, the highest peak in the U.S above 20000 ft above sea level and about 18000 ft tall, is 158 straight miles from Fairbanks, Alaska according to a Google search, but it can been seen from some parts of the city. That is key. Fairbanks according to our article about the city is 140 miles South of the Arctic Circle. According to our article, the sun’s disk is above the horizon for 21 hours and 49 minutes at the summer solstice. Therefore, Fairbanks doesn’t experience the midnight sun, but a short “white night” each day during this period. Height above the ground does affect daylight lenghth due to the curvature of the Earth and there are many examples. Given all these facts, let’s suppose that Mt Denali was right next to Fairbanks at the same latitude, 140 miles South of the Arctic Circle, and given that one can deduce that the visibility on a clear day would extend slightly beyond the Arctic Circle when looking North at the top of the summit if Mt Denali were to be at the same latitude as Fairbanks, would the summit get 1 to several days of the midnight sun around summer solstice, but of course not 1 to several days of polar night around winter solstice? Willminator (talk) 05:38, 14 June 2018 (UTC)

Doesn't the Continental Divide go north of Fairbanks? Mountains might block the Sun. What counts as sunset is kind of fuzzy though, pretending that stuff over sea level is air and everything below is water is often done even if your entire horizon is Lake Titicaca and you're treading water almost up to your eyeballs. Pretending you're levitating at Lake Titicaca altitude and surrounded by a sea level horizon with a lot of "distance from Earth"-induced horizon dip makes sunset times there a lot more inaccurate than just assuming the horizon's at lake elevation obviously. And even the Appalachian Range only 2km high can shield enough atmosphere from direct sunlight to make twilight noticeably darker than if that range didn't exist and it was all sea level like the simplified model so why not count mountains as being able to cause sunset? That'd cause a problem of what's the smallest thing that can cause night is though. Is it nighttime if a skyscraper hides the Sun at high noon?, or even your hand? Obviously not so where's the cutoff? Ignoring topography, Fairbanks is close enough to the Arctic Circle to cause midnight sun at Denali's elevation at the city center but ignoring topography though (sea level virtual horizon) Sagittarian Milky Way (talk) 07:04, 14 June 2018 (UTC)

Can "genetically identical" populations belong to different species?

Hello. In "Integrative Taxonomy Resolves Three New Cryptic Species of Small southern African Horseshoe Bats (Rhinolophus)", Taylor et al. admit that their study population of Rhinolophus is "genetically identical" to the existing species R. simulator, but they go ahead and recognise it as a distinct species anyway "on morphological and acoustic grounds". Is this reasoning scientifically solid? If so, why is it not applied to the numerous other species that display clear intra-specific variation, such as Canis lupus? It does seem odd to separate genetically identical populations into different species. Thanks.--Leptictidium (mt) 08:59, 14 June 2018 (UTC)

Genetically identical insofar as they sequenced, which was to a very limited extent. The paper in question, here, only obtained a partial sequence for a single mitochondrial gene, and took limited DNA sequencing from prior publications to use in their analysis. Their hypothesis is that possibly a small portion of the genome, mitochondrial and/or nuclear, is identical between different species due to rare and/or historical introgression events. But one would still expect the great bulk of the genomes to show long-term divergence from one another. That data has not been generated yet. Someguy1221 (talk) 10:25, 14 June 2018 (UTC)

Right. There is no such thing as populations that are fully genetically identical. Even the cells within a single individual body are not fully genetically identical. Looie496 (talk) 17:54, 14 June 2018 (UTC)

It may be possible to have genetically identical species produced via infectious speciation. (Wolbachia being the known example) [6] Biology never stops getting weirder. ;) Wnt (talk) 21:51, 15 June 2018 (UTC)

Human genetics

Can someone help me solve this problem?

In population that is in equilibrium there are four times as more dominant alleles than recessive ones. What is the frequency of the dominant trait in that population?

p² + 2pq + q²

p + q = 1

p = 4q

q = 1/5p

q = .2

p = .8

.2² = .04

1 - .04 = .96

Vs⁶₅⁰⁷ 13:00, 14 June 2018 (UTC)

It looks like you have some chaff there, but note that allele frequency is based on how many alleles are present, and you just said that, i.e. it's p. Usually it's slightly harder to figure out because you have to infer it from the phenotype rather than just being handed the information. Wnt (talk) 13:36, 14 June 2018 (UTC)

It's not about allele frequency, but rather phenotype frequency. So I guess I did correct there... Vs⁶₅⁰⁷ 14:48, 14 June 2018 (UTC)

Oooops, I misread that. Yeah, the dominant trait frequency is 1-0.2*0.2 as you say (at least, assuming the recessive isn't lethal balanced by some advantage for the heterozygote or something similarly wacky) Wnt (talk) 22:29, 14 June 2018 (UTC)

Plugging home appliances in the EU and the US

It seems to me that EU plugs allow the user to plug in a devices in two ways, but the US plugs only allow one way of plugging a device. The same discrepancy applies to other plug types, from other places. They are just examples. Why are they different? --Doroletho (talk) 16:48, 14 June 2018 (UTC)

Our AC power plugs and sockets article talks about all the different countries' standards. For example, a a non-reversible connection where one wire is hot and the other neutral guarantees to the device which is which. That can be a safety feature, for example, to reduce the likelihood that someone will touch something that is connected to the hot or how much of the device remains energized when a switch is "off". It wasn't that long ago that US also had reversible plugs and non-polarized outlets. DMacks (talk) 17:26, 14 June 2018 (UTC)

There a multiple standard of mains plugs in the EU, some of which are polarized, and some not. LongHairedFop (talk) 13:41, 16 June 2018 (UTC)

How do researchers make animals neglectful of their offspring?

I have heard of research experiments in which researchers compare caring animal parents and neglectful animal parents. My question is, how did the researchers manipulate this? Is it some sort of gene that they knock out? Do they train animals to behave a certain way? SSS (talk) 19:31, 14 June 2018 (UTC)

There are always some animals that neglect their offspring. Ruslik_Zero 20:10, 14 June 2018 (UTC)

In some species (including rodents and sheep) animals will neglect their offspring if they don't smell right. Looie496 (talk) 22:09, 14 June 2018 (UTC)

Treatment of mothers with naloxone or genetic mutations that block pheromone receptors will do it. [7] Wnt (talk) 22:31, 14 June 2018 (UTC)

Simply separating the parents from the offspring seems like the simplest way to ensure parental neglect. CodeTalker (talk) 23:26, 14 June 2018 (UTC)

Identify unknown mushroom species

I would like some help identifying these species. These first two photos are of a mushroom that is very similar to a garden-variety mushroom but it is definitely not the edible kind. I found it growing on tbe U.S. Courthouse lawn, and it is really quite toxic. It has a strong earthy or musty odor with something faintly pungent and acrid to it, which immediately caused my eyes to dilate and my stomach to cramp up, and I almost passed unconscious that afternoon and I woke up in the middle of the night with chills and leg cramps. That's just the smell. I really wouldn't eat it. My eyelid is still twitching with an odd tic from that and I heard the neighbor's dog went blind sniffing this kind of mushroom.

The mushroom below looks like some kind of morel to me. I'm not really sure, but it has an overpowering foul odor to it. It was growing on a street corner downtown.

I'm suspecting the spores are spread by the sorry girls and frat boys at University of Alaska Fairbanks who frequent the aforementioned courthouse demanding a total gun ban certiorari in case one of the sorry girls has to dump her boyfriend and all the sisters need a campus police escort to make it safely back to their dorm rooms after their mental health counseling appointments. Any positive I.D.? Need more info. justinacolmena (talk) 20:55, 14 June 2018 (UTC)

It could be Agaricus_xanthodermus which looks like a very large Champignon and smells of phenol. The last picture can be the same when young and by dry weather but I think more for example of some Tricholoma or Lepista. Morel is completely different.194.174.76.21 (talk) 14:42, 15 June 2018 (UTC) Marco Pagliero Berlin

No yellow. No phenol smell. Head is thicker and rounder. Absolutely no one is going to eat this mushroom without ill effects. The last one is not the same as the others. It has a completely different smell. Tricholoma or Lepista are too flat-headed. The shape of this one is pointy-headed like the morel, but it has a droopy, rain-split cap which the morel lacks. False morel? Probably not even. justinacolmena (talk) 18:50, 16 June 2018 (UTC)

But if you're eating unidentified mushrooms, you really should reconsider your priorities. --jpgordon^{𝄢𝄆 𝄐𝄇} 17:26, 15 June 2018 (UTC)

Excuse me. You must have been high on drugs if you thought I was "eating" this mushroom and still alive today. justinacolmena (talk) 18:50, 16 June 2018 (UTC)

June 15

Phobos orbital height - I must be missing something

Phobos orbits at a height above the Martian datum of 6km. Olympus Mons is 26km in height. Maybe Phobos has a stable orbit and won't collide with it, but I feel like I'm missing something or misinterpreting the data? Surely Phobos can't really be that low? Dr-ziego (talk) 12:10, 15 June 2018 (UTC)

Where did you get the idea that Phobos orbits 6 km above Mars? It's about 6,000 km, per our article. Matt Deres (talk) 12:19, 15 June 2018 (UTC)

It'll collide eventually causing a titanic explosion. Sagittarian Milky Way (talk) 13:48, 15 June 2018 (UTC)

Phobos has an orbital inclination of 1.093° degrees, relative to the Martian equator. Olympus Mons is located 18.65° North of the Martian equator. Therefore, Phobos never overflies Olympus Mons. LongHairedFop (talk) 13:39, 16 June 2018 (UTC)

Oh right, that too. Sagittarian Milky Way (talk) 13:54, 16 June 2018 (UTC)

On another hand, Pavonis Mons is on the equator. —Tamfang (talk) 07:29, 17 June 2018 (UTC)

Pavonis is 1.48°North, so Phobos doesn't overfly it. However, IIRC, the inclination of moon's orbits can vary over times, so eventually Phobos will overfly it. LongHairedFop (talk) 22:05, 17 June 2018 (UTC)

What airliner requires the most runway at over 40 Celsius and 0 to 1000 feet elevation?

I've heard it might not actually be the Airbus A380. Sagittarian Milky Way (talk) 13:44, 15 June 2018 (UTC)

For passenger aircraft, it is the Airbus A380. If you look into cargo planes, the AN-225 Mriya requires more (about 9,000 ft for the A300 and 10,000 for the Mriya). 209.149.113.5 (talk) 14:00, 15 June 2018 (UTC)

Isn't there a big difference in minimum recommended runway between frigid, low ladenness and good weather and hot, highly laden and unfavorable wind? Or landing in tropical rain while highly laden for landing lengths? Sagittarian Milky Way (talk) 14:22, 15 June 2018 (UTC)

Yes. A pilot should use the temperature, humidity, wind speed/direction, and air pressure to calculate the "density altitude", which is the altitude the aircraft appears to be at if the conditions were optimal. Then, with the density altitude, the minimum required runway length is calculated. There are cases where normal airports shut down runways because they are too short for the calculated density altitude. Minimum length can get very long. In Tibet, there is a runway that is at least 3 miles long - and sometimes it can get too short. 209.149.113.5 (talk) 14:49, 15 June 2018 (UTC)

This isn't under the above conditions and also doesn't seem to clearly specify it's referring to the rare 747-8I (passenger) variant but for "minimum requirements that apply to an aircraft at Maximum Certified Takeoff Weight (MTOW), taking off at sea level under ISA condition" gives Airbus A380-800 2900 metres and Boeing 747-8 3050 metres [8] Nil Einne (talk) 16:44, 16 June 2018 (UTC)

This quick guide also gives similar figures for the MLW [9]. Actually the 747-400 is the also higher. Nil Einne (talk) 16:59, 16 June 2018 (UTC)

I think you should be able to work out from these documents if the above is correct for the specified conditions [10] [11] Nil Einne (talk) 17:11, 16 June 2018 (UTC)

So it appears that at maximum takeoff weight, 0 pressure altitude and 30C sea level equivalent (it doesn't give more) the 747-8I needs a longer takeoff than the A-380-800 but it's roughly the same at 1,000 feet and the other way around above that. Sagittarian Milky Way (talk) 22:30, 16 June 2018 (UTC)

Short Question About Astronomy

Earth in its Orbit

The occurrence of the "Number of solar noons (middays)" is always equal to "Number of solar midnights"

The diagram (not to the scale) on the right-hand side depicts the path traced by the earth for day and night in its orbit (either circular or elliptical) around the sun. Any point on the outer circle represents solar midnight while on inner circle solar noon. The length of an outer circle is greater than the length of the inner circle and hence Arc I > Arc II. This means the appearance of midnight points (anti noon) are more than middays points (solar noon) when the earth revolves around the sun in its orbit – Any special reasons

As # of midnights = # of solar noons when the length of arc I = length of arc II but since arc I > arc II, therefore

Are solar noons and solar midnights equal in numbers in the arc I and arc II or after the completion of 4 years?--Eclectic Eccentric Kamikaze (talk) 13:57, 15 June 2018 (UTC)

... or another way of looking at the situation is that the midnight point is always moving faster than the noon point. Dbfirs 14:46, 15 June 2018 (UTC)

The first thing to bear in mind is tidal force. If the Earth did not rotate, or more precisely, were tidally locked, its outer edge would have to revolve faster than the inner edge, like a phonograph record. This doesn't precisely match the expected orbital period, so there are tides raised by the Sun - the other part of the planet gets a gentle nudge like it should fly off to space, while the inner has a gentle nudge to fall toward the Sun, though of course if separated somehow neither would get far before returning where they were in some sort of elliptical orbit, sans planetary integrity. So the point is, the "midnight" part of Earth is always going a bit faster to make up the distance. Wnt (talk) 18:48, 15 June 2018 (UTC)

In other words: there are just as many middays on the inner circle as midnights on the outer one, but space (not time!) between midnights is a bit larger. Right? 194.174.76.21 (talk) 10:15, 18 June 2018 (UTC) Marco Pagliero Berlin

With rotating systems, it is often more useful to consider things in terms of angles, rather than distances. The earth is moving 2pi radians per year. There are 365.25(ish) middays and midnights for a point on the surface in each year. Therefore, each successive midday is separated by 2pi/365.25, and the same for each successive midnight. The midnights are further out, so the linear distance between them is greater, but that's not relevant here. MChesterMC (talk) 10:31, 18 June 2018 (UTC)

Bees and butterflies question

There has been an abortion debate in Argentina in those days, as the Congress is discussing a bill to legalize it. But there is a part of the text of the bill that I did not understand: translated to English, instead of talking about women, it talks about "women and people that may become pregnant". It feels weird having to ask this, but does such wording make sense, can someone other than a woman become pregnant? I know that there are transsexual people and sex reassignment surgery, but is that enough to make a person that was once a man to become pregnant and deliver a baby? Did that ever happened? Or is it just political correctness gone mad? Cambalachero (talk) 19:17, 15 June 2018 (UTC)

"No results found for 'women and people that may become pregnant'".[12] Maybe it is not available in English. Can you post the text in the appropriate language? Bus stop (talk) 19:25, 15 June 2018 (UTC)

If "women" is taken to mean "adult females" then of course other people who may become pregnant are females below the age of adulthood. DuncanHill (talk) 19:28, 15 June 2018 (UTC)

And see also male pregnancy. DuncanHill (talk) 19:29, 15 June 2018 (UTC)

Also, women can consider themselves men and still become pregnant. Bus stop (talk) 19:40, 15 June 2018 (UTC)

That's under transgender pregnancy. Also, some people regard themselves as a third sex, etc. My feeling is that "women and people who may become pregnant" is inelegant; one (presumably the latter) should suffice for most intentions. True male pregnancy in humans is probably not far off anyway, so "people" would seem like a reasonable replacement in a forward-looking statement. Wnt (talk) 21:45, 15 June 2018 (UTC)

It's downright criminal that every news outlet to discuss this bill doesn't tell us what it's frickin' name is!. Makes it very hard to search for. Still looking - I was hoping to just read the Spanish version directly. Someguy1221 (talk) 22:16, 15 June 2018 (UTC)

OK, I think this is the bill that was just voted on, but I don't see what the OP is referring to anywhere. Someguy1221 (talk) 22:54, 15 June 2018 (UTC)

The term in Spanish is "mujeres y personas gestantes". I have not found a single-word translation of "gestante" to English, so I made the translation myself. The word would be an adjetive for a living being with the hability of becoming pregnant. In any case, I was not asking about the bill (that's a local bill in a Spanish-speaking country, after all; I do not expect many people abroad to be following those news events) but about the pregnancy aspect. If I understood the article, barring discussions of what would be theoretically possible there are no actual cases of children born from male-to-female transgender people. There are some named cases of children born from female-to-male transgender people (that is, someone who was born as a woman, and retains all the required organs), but how often does that happen? Do they get pregnant as easily and frequently as straight women, or are those special fortunate cases? Cambalachero (talk) 00:36, 16 June 2018 (UTC)

[13]. It has apparently been the standard language used by the Ministry of Health since 2015 in cases regarding abortion, and explicitly with transmen and similar situations in mind. As for how often this happens, we have an article on Transgender pregnancy, but no statistics, and I also could not find any statistics on this in the scientific/medical literature. I would assume that it is quite rare. However, as to how easy it is, that depends. The majority of transmen do not undergo sex reassignment, leaving them physically as capable of conceiving and bearing a child as they would be otherwise. There is insufficient data to say what the long-term effects of hormone transition therapy are on the fertility of transmen. It's believed that such therapy impairs fertility, especially while it is being taken (and may also impact fetal development), but it's not clear to what extent. There is a review on the subject here, but mostly it just clarifies that we don't know a lot. Someguy1221 (talk) 00:53, 16 June 2018 (UTC)

"Pregnant people" is also used more and more in English these days, rather than the phrase "pregnant women" that was nearly exclusively used historically. Some examples: [14] [15] [16] [17]

Something of an aside, but "bees and butterflies"? Are they the Argentine equivalent of the birds and the bees? DuncanHill (talk) 00:59, 16 June 2018 (UTC)

The equivalent of Spanish gestante is English gestant from gestation, which is a rather unsual word compared to pregnant. --62.99.192.174 (talk) 23:16, 16 June 2018 (UTC)

I am reminded of the term Embarazada. Bus stop (talk) 23:25, 16 June 2018 (UTC)

June 16

if the half-life of estradiol cypionate is around 8 days, what would be the half life of estradiol dicypionate?

Is there a rule of thumb for estimating the half-life depot steroid medications if both hydroxyl groups on a steroid are esterified versus just one hydroxyl group? I note that estradiol dipropionate is an ester described as having a relatively long half-life, but this article seems to imply that diesterification can lengthen the half-life by two to eightfold, since before the innovation of estradiol dipropionate, most esters were injected 2-4 times a week, now could be injected once every 1-2 weeks. Yanping Nora Soong (talk) 04:12, 16 June 2018 (UTC)

According to Ullmann's "Hormones", esterification of estrogens increases their duration of action. A similar approach would be increasing the carboxylic acid chain length (like in the series Estradiol valerate, Estradiol enanthate, Estradiol cypionate). Furthermore, alkylation of estradiol derivatives at position 17 (ethinyl estradiol, quinestrol) increases their oral activity many times. --62.99.192.174 (talk) 23:39, 16 June 2018 (UTC)

This doesn't answer my question. I already know that!! I can't figure out how to apply Bates' equation in radioactive decay for a decay chain to this problem. Yanping Nora Soong (talk) 01:30, 17 June 2018 (UTC)

Do I add the half lives?? Do I multiply the half lives? I've tried all sorts of approximations and differential equations. Is the half life more like 16 days or 64 days?? The problem with the Bates equation is that it does a poor job when k1 and k2 are very close in magnitude, because you have to divide zero over zero. Agh! Yanping Nora Soong (talk) 01:33, 17 June 2018 (UTC)

I thought you were trying to deduce the pharmacokinetics of some hypothetical estradiol esters. But is it first order, zero order, nonlinear? First there is hydrolysis of the ester, then there is the metabolism of the estradiol, each of which seem to follow different kinetics, also depending on the route of administration. A Google search for "estradiol ester pharmacokinetics" and "estradiol ester metabolism kinetics" throws up lots of interesting hits. --62.99.192.174 (talk) 02:12, 17 June 2018 (UTC)

This is a a depot *diester* prodrug. Both functional groups must be removed to produce the active drug. I'm not interested in monoester pharmacokinetics and I already did the relevant research, hence why I'm here. I also tutor biochemistry... Also why aren't people reading my entire question?  :( I really need help with the Bateman equation. I don't need a lecture on routes of administration for a depot formulation? Yanping Nora Soong (talk) 05:19, 17 June 2018 (UTC)

@Yanping Nora Soong: The Bateman formula gets very complicated for intermediates in a decay chain. However, the stability of the first isotope, or compound, has nothing to do with anything that comes afterward (some of those pi terms where you multiply a series of numbers don't have anything to multiply). In this case it probably is easier to redo the derivation of the math than to figure out what the formula means. You are looking at estradiol dicypionate -> estradiol cypionate -> estradiol, I think. Now do you already know the biological activity and the rate of decay for each of these intermediates? Then we can go over it. But if your assumption is that the first ester is broken at the same rate as the second, well, to begin with, we have no idea if that's true since this is biology (and chemistry...), but if it is true, then half-life of estradiol cypionate should logically be the point where just 25% of the estradiol dicypionate has been broken down to estradiol (a 50/50 chance for each bond), and two half-lives for estradiol (that would leave 25% left) would correspond to leaving 1-0.75*0.75 = 44% of the estradiol dicypionate or cypionate left. Note I'm not expecting a true half-life relationship for the "E1-2C -> estradiol decay" starting with E2C because the nature of "E1-2C" will change over time. Wnt (talk) 13:28, 17 June 2018 (UTC)

1 AU

How thick is the belt? What is the height and width? 123.108.246.27 (talk) 18:46, 16 June 2018 (UTC)

What belt? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:23, 16 June 2018 (UTC)

See Astronomical unit. Ian.thomson (talk) 19:45, 16 June 2018 (UTC)

Retaining carbonation

Suppose I want to open a cold, carbonated beverage and have it retain the maximum possible carbonation when I take the first sip, right after the pressure has dropped to atmospheric. Holding constant things like starting temperature and without previous agitation, do I lose less carbonation by the most sudden pressure drop, like popping the cap on a glass bottle, or by lowering the pressure as slowly as possible, like v-e-r-y slowly unscrewing a screw cap, and letting the pressure drop infinitesimally slowly? Or would just unscrewing a cap at a typical fast rate retain the most bubble? What is the scientific basis for the conclusion? Edison (talk) 19:06, 16 June 2018 (UTC)

If you open the cap as slowly as possible, the bottle will have been open for a long time, and will thus be entirely flat. For openings that last no more than a few seconds, I don't think it makes any appreciable difference, except that if you actually let the gas undergo free expansion it won't cool off and will thus keep the interior a bit warmer (which accelerates loss of the dissolved gas). --Tardis (talk) 21:38, 16 June 2018 (UTC)

I guess my phrasing left open the prospect of taking an hour or more to unscrew the cap, leaving the pop warm and flat. In practice, I might do it “fast” in one-half second from first escape of pressure up to 10 seconds to very slowly release the pressure from the time it is first heard hissing out. I wondered if a sudden drop, like rapid unscrewing or popping a metal cap from a glass bottle would produce a shock causing a greater loss of carbonation, similar to shaking it or setting it down hard before opening it, which clearly causes a massive loss of carbonation. As I asked initially, what topics in chemistry address the issue of the rate at which gas dissolved in liquid is liberated in a solution at atmospheric pressure. From experiments done long ago I think the volume of carbon dioxide might initially be equal to or even greater than the volume of the liquid, which itself is amazing. Edison (talk) 14:12, 17 June 2018 (UTC)

From a knowledge of brewing and beverages I can confirm your last point. The volume of CO₂ per volume (of liquid) is for real ale in good condition considered to be a little over 1. However, in other beverages it can be several times this. To quote from Beverages: Technology, Chemistry and Microbiology by Alan H. Varnam & Jane P Sutherland (Chapman & Hall 1994), p 92: "The optimum level of carbonation varies according to the flavour and perceived character of the different drinks. In general terms, fruit drinks are carbonated to a low level (ca. 1 volume CO₂), colas, ginger beer, alcohol-containing drinks, etc., to a medium level (2-3 volumes CO₂) and mixer drinks such as tonic water and ginger ale to a high level (ca. 4.5 volumes), to allow for dilutions in the non-carbonated liquor. Soda water filled into syphons, however, contains up to 6 volumes of CO₂ to maintain internal pressure during use."

My personal experience (OR warning!) of opening bottles of carbonated drinks with a higher than usual overpressure, perhaps due to warming, agitation, prolonged secondary fermentation in the container (which for real ale is by definition mandatory), or a combination of these, is that rapid opening may lead to immediate excessive foaming (aka 'fobbing') but that this can be mitigated by slower release of pressure taking at least several seconds – longer than that might reduce the over-foaming even more, but who would have the patience? {The poster formerly known as 87.81.230.195} 2.125.75.224 (talk) 13:23, 18 June 2018 (UTC)

Mystery tide pool creature (Southern California)

What is this thing? I assume it's just the mouth/siphon of something hiding in a rock crevice, and it was shooting jets of water. 169.228.163.250 (talk) 20:10, 16 June 2018 (UTC)

Dejavacrapped link: [18] Every pageview you make on the internet that Google doesn't know about is a theft, and therefore, a revolutionary act. Wnt (talk) 22:21, 16 June 2018 (UTC)

Kind of gross looking. See Trypophobia. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:41, 16 June 2018 (UTC)

I see the extremities of many thin tentacles sorrounding some thick ones sorrounding a mouth. It seems to me to be a retracted sea anemone waiting for high tide. Some see anemones do live in rock cavities, although I don't know whether they can dig one themselves. 194.174.76.21 (talk) 15:49, 18 June 2018 (UTC) Marco Pagliero Berlin

June 17

Bateman equation

Suppose A decays to B via first order rate constant k1 and B decays to C via first order rate constant k2. All the treatments of the Bateman equation in radioactive decay I've found assume that k1 is never close in magnitude to k2. This is really frustrating because I want to use it to approximately model to my pharmacological diester duration of action problem. If k1 = k2 (you would think this is a simple situation!!) then you get division of zero over zero and l'Hôpital's rule doesn't solve the problem. (I've even tried using the ratio k2/k1). Help? If k1=k2=0.086 (corresponding to half lives of 8 days each), then how much time does it take for half of A to break down to C? Is it more like 16 days or 64 days? Yanping Nora Soong (talk) 01:43, 17 June 2018 (UTC)

I get about 18 days, just using a secret engineer's method (a spreadsheet model, renders most calculus redundant). The mass of B is a maximum at about day 11. Greglocock (talk) 06:01, 17 June 2018 (UTC)

In your problem when $k_{1}=k_{2}=k$ and $A(0)=1$, $B(0)=0$ and $C(0)=0$

$C(t)=1-e^{-kt}(kt+1)$.

which, when $C=1/2$, leads to $kt\approx 1.65$ and $t\approx 1.65/0.086=19.2$ days. Ruslik_Zero 10:19, 17 June 2018 (UTC)

Thank you!!!!! I am also going to write a script for a Monte Carlo method later. Now I suspect because of increased steric bulk that k2 is slightly bigger than k1 (but around the same order of magnitude), but the problem k1=k2 was bugging me because I was worried that the half-life was unbounded. It turns out that HRT users report that a med that includes this diester (Climacteron) is injected every 30 days (although manufacturer monograph says 4-8 weeks). Yanping Nora Soong (talk) 17:21, 17 June 2018 (UTC)

Your problem is the repeated eigenvalue issue in linear differential equations. It’s usually as far as i know solved by multiplying C1e^kt by t and then adding C2e^kt, which is the same thing really as what the engineer said above. Something similar in decaying harmonic motion is called “criticallydamped.” — Preceding unsigned comment added by 67.128.146.22 (talk) 18:10, 17 June 2018 (UTC)

Hmmmm... per my logic in the last question section I would think that if the half-life of each of two bonds is 8 days, then after 19.2 days, each bond is only unbroken 19% of the time, so the amount with both broken at that point is 81%*81% = 66%. I think the difference in the math above is that you suppose the half-life of A is the same as the half-life of B -- but in the previous question A has *two* ester bonds either of which can be broken while B just has one, so we'd expect a different rate constant. Again, I don't really know the stability of A and it doesn't have to be half of B or any other particular value, but I just thought I should point this out. Wnt (talk) 21:42, 17 June 2018 (UTC)

I've realized this -- there are two intermediates -- but I made that approximation to try to obtain a value that made sense. I saw a "complex" chain treatment that looked like my problem, and I'll try a Monte Carlo method later. Thank you so much!!! Yanping Nora Soong (talk) 02:04, 18 June 2018 (UTC)

• For the complete math: the original problem is a "simple" matrix differential equation ${\begin{bmatrix}{\dot {A}}\\{\dot {B}}\end{bmatrix}}={\begin{bmatrix}-k_{1}&0\\k_{1}&-k_{2}\end{bmatrix}}{\begin{bmatrix}A\\B\end{bmatrix}}$ (add a column/row if you want C), which does have an analytical solution in the general case. Tigraan^{Click here to contact me} 11:47, 18 June 2018 (UTC)

Dividing line between angina and heart attack

Doesn't angina always involve at least some loss of oxygen to the heart, and therefore a possibility of damage? So if a self-interested hospital wants to increase revenue, what’s to stop the hospital from calling a case of angina a heart attack? Is there news or opinions in media about this as a conflict of interest? Thanks 67.128.146.22 (talk) 10:01, 17 June 2018 (UTC)

There are tons of literature about differential diagnosis of heart attack and angina pectoris. You can search yourself in Google. Ruslik_Zero 12:23, 17 June 2018 (UTC)

”you can search yourself in Google” is a weird response for a volunteer at reference desk.67.128.146.22 (talk) 17:57, 17 June 2018 (UTC)

At an academic reference desk, the answer is sometimes "here are the search terms you need; look through them, and feel free to come back if you want further assistance". Nyttend (talk) 01:10, 18 June 2018 (UTC)

(I am assuming, based on your IP address, that you're interested in the U.S. "healthcare system".) Most U.S. hospitals bill on a fee-for-service basis; that is, the charges are based on the services and procedures performed, not on the specific diagnosis attached to a particular patient. If a patient undergoes cardiac catheterization, the bill is the same whether the diagnosis is "angina" or "infarct". (That oversimplifies a bit; in practice the billing goes into rather a lot of arcane detail, with separate charges for staff, operating room time, drugs, instruments, tests, etc.)

Now, if a hospital makes a habit of over-diagnosing and thereby performing unnecessary tests and procedures, pushback happens in a number of ways and places. Insurance companies tend to notice when one hospital seems to have unusual patterns of diagnosis and treatment, and will start to deny reimbursements that aren't accompanied by sufficient documentary evidence. Overdiagnosis to increase billings is a gross breach of medical ethics, and can lead to both civil and criminal penalties for the parties involved.

(More common and more difficult to deal with is over-testing and over-treatment done in good faith. For physicians, it's hard – and sometimes legally risky – to tell a patient that expensive tests aren't necessary; it's hard to tell a patient that the best way to treat their condition is sometimes to do nothing. This New Yorker article is an accessible overview.) TenOfAllTrades(talk) 15:00, 17 June 2018 (UTC::thanks good response67.128.146.22 (talk) 17:57, 17 June 2018 (UTC)

June 18

Terminal dehydration mechanism

I looked for this on Google, but all the results I saw were too technical for me to understand.

If you die of terminal dehydration, what's typically the reason of death? Is it dehydration itself (and in particular, what fatal effect does extreme dehydration cause), or is it some side thing, like a simple illness (e.g. the sufficiently dehydrated immune system can't function properly), or urea poisoning (you don't have enough water to urinate, so you build up urea to a fatal level), or something else? Nyttend (talk) 01:07, 18 June 2018 (UTC)

I dont have expert medical knownledge. Good chance someone else can answer this way better but i think i have the basics right and you wrote that you didnt want tomuch detail anyway: It depends on your body's condition, training and your surrounding. In a hot area you will fail to regulate your body temperature, overheat and then multiple vital organs may fail. If you are used to living in a hot desert your body will adapt and you likely already have allot of experience with dehydration. So you may survive a level of dehydration that would kill anyone else even in an earlier stage. In a mild climate your kidneys will likely stop working first and as a result you slowly become "toxic", which will affect other organs. So the typical reason of death is some (or multiple) Organ dysfunction(s). Because many organs have a vital function its hard to pin the cause down to one. --Kharon (talk) 02:35, 18 June 2018 (UTC)

Giordano Bruno crater

Per our article, Giordano Bruno (crater) is on the far side of the Moon "that always faces away from Earth", so how five Canterbury monks could have observed the crater's formation? Thanks. 212.180.235.46 (talk) 07:01, 18 June 2018 (UTC)

There is no actual evidence that they did, but the location of the crater isn't the real issue. It's just behind the limb, and from our article "At this location it lies in an area that can be viewed during a favorable (sic) libration". Also, debris would be thrown much higher, out past the limb, even if the impact itself wouldn't be visible. Fgf10 (talk) 08:02, 18 June 2018 (UTC)

Or favourable (sic). ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:07, 18 June 2018 (UTC)