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October 12

Electromagnet: Loops vs current

Let's say I'm building an electromagnet, and I have a fixed amount of copper, and a fixed amount of power. What's better: More loops, higher voltage, lower current; or fewer loops, lower voltage, and higher current? What if I can vary the power, what's better fewer loops and higher current or vice versa? Ariel. (talk) 00:18, 12 October 2021 (UTC)

Suppose you have n windings. With a fixed amount of copper, the cross-sectional surface area of the wire goes with 1/n, so the resistance per unit of length goes proportional to n. The length of the wire goes with n, so the resistance goes with n. I=sqrt(P/R), so with constant power, the current goes with 1/n. The magnetic field goes with I times n, so for a fixed amount of copper and a fixed power supply, the number of windings doesn't matter.

There are some other considerations. The current not only runs in the electromagnet, but also in the wires connecting it to the power supply. A higher current leads to more losses there and to difficulty switching it off (not more difficulty switching it off. The lower inductance of the coil with less windings compensates for the larger current. After all, the energy stored in the magnetic field is the same). Higher voltage requires better insulation between the wires in the coil. A longer wire means you have to cover a larger area with this thicker insulator, which takes volume and may pose a problem for cooling the electromagnet. PiusImpavidus (talk) 09:23, 12 October 2021 (UTC)

October 13

fenilbeta

In Primo Levi's If This is a Man (chapter Die drei Leute vom Labor), he tells his experience of how, while working at the "chemical" Kommando at the Buna plant near the Monowitz concentration camp, he had to work with fenilbeta. It comes in 60-Kg bags. It has a sharp odor that gets in the prisoners' uniforms. If it gets between the skin and the uniform in summer, it sticks to the sweaty skin and corrodes it. I suspect it is PHENYL-beta-NAPHTHYLAMINE but there is no article about phenyl-beta-naphthylamine. There are two articles about Naphthylamine, though. My questions are:

• What is the usual name of fenilbeta?
• What is it used for (especially at the Buna plant)?

Thanks. --Error (talk) 00:39, 13 October 2021 (UTC)

In Survival In Auschwitz (p. 136) by Primo Levi, it is translated as "phenylbeta". Alansplodge (talk) 10:44, 13 October 2021 (UTC)

Possibly:

N-Phenyl-beta-Naphthylamine is a light tan or gray flake or powder. It is used in making rubber products, other chemicals, and as a stabilizer in lubricants. This chemical is no longer used in the United States... Contact can irritate the skin and eyes.

Buna Werke was a synthetic rubber plant.

Alansplodge (talk) 11:09, 13 October 2021 (UTC)

See the Pubchem summary of uses, section 10.4 and the short WP article de:N-Phenyl-2-naphthylamin (in German), which confirms Alansplodge's suggestion. Mike Turnbull (talk) 11:43, 13 October 2021 (UTC)

Regarding reverse current after zener breakdown

Can I light the bulb from circuit even after zener breakdown? I know reverse current gradually increase after increasing input voltage after zener breakdown. I am confused because of the term "reverse" present here.Rizosome (talk) 02:21, 13 October 2021 (UTC)

I think you need a much more better understanding of basic electromagnetic terminology, such as "current," before you start trying to understand much more complex concepts, such as zener breakdown. I'm not trying to be condescending, either, but you have had several questions recently that show a fundamental misunderstanding of what terms like "current" mean. Just as one should learn to walk before they learn to run, you probably need a more basic understanding of electromagnetic theory before jumping to things like the Zener effect that depend on things like quantum tunneling or understanding p–n junction type semiconductors. --OuroborosCobra (talk) 20:46, 13 October 2021 (UTC)

Ok, is this reverse current from aforementioned zener breakdown considered as Backfeeding? Rizosome (talk) 05:05, 14 October 2021 (UTC)

Swimfins' drag

To what extent, if any, the swimfins' advantages are offset by the muscular efforts to overcome drag, which is greater than without them? Thanks. 212.180.235.46 (talk) 20:04, 13 October 2021 (UTC)

October 14

New Shepard flight profile

This article from CNN (https://www.cnn.com/2021/10/13/tech/william-shatner-space-blue-origin-everything-you-need-to-know-scn/index.html) states:

New Shepard's suborbital fights hit about three times the speed of sound — roughly 2,300 miles per hour — and fly directly upward until the rocket expends most of its fuel. The crew capsule then separated from the rocket at the top of the trajectory and briefly continued upward before the capsule almost hovered at the top of its flight path, giving the passengers a few minutes of weightlessness. It works sort of like an extended version of the weightlessness you experience when you reach the peak of a roller coaster hill, just before gravity brings your cart — or, in this case, your space capsule — screaming back down toward the ground.

Am I to understand that they only experience weightlessness at the very top of the flight trajectory, or is that simply a limitation of the rollercoaster metaphor, since on a rollercoaster the occupants are strapped in and can't experience weightlessness while the cart is moving downward? I would have thought that the occupants of New Shepard experience weightlessness as long as they are in free fall, since they and the capsule are accelerating toward the ground at the same rate. Is that incorrect? --Puzzledvegetable 00:25, 14 October 2021 (UTC)

The article Free fall gives a pretty good explanation and points out that free fall occurs whenever gravity is the only force acting on something. Hence the rollercoaster analogy is a poor one because, as you say, the occupants are subject to forces from the straps. Mike Turnbull (talk) 08:59, 14 October 2021 (UTC)

​Is it correct that the occupants only experience weightless at the very top of their trajectory, because the flight is so low that the atmosphere gets thick enough to provide a noticeable normal force very shortly after they start falling? In other words, when they experience weightlessness, is approximately half of it felt while moving upwards after turning the engine off and the other half felt when falling back down to approximately the altitude that they turned the engine off at, or is most of the free fall spent moving downwards toward the Earth, with the only the very beginning occurring while still moving upwards?

Do you know where I can find technical information like this about the flight? --Puzzledvegetable 11:50, 14 October 2021 (UTC)

At the height when the manned capsule detaches from the rocket and starts "free fall" (although it still ascending for a time), atmospheric drag is minimal, so weightlessness is experienced. There were in total about three minutes of weightlessness in a flight lasting ~ten minutes, so you might think (and I would agree) that it is all a rather expensive publicity stunt. The free fall ended roughly when the parachutes were deployed which of course is only sensible when the atmosphere is dense enough that its drag can act on them. Mike Turnbull (talk) 14:37, 14 October 2021 (UTC)

​Do they experience weightlessness up until the moment the parachutes deploy, or does the atmosphere get thick enough to provide a normal force before it gets strong enough to fill the parachutes? --Puzzledvegetable 16:34, 14 October 2021 (UTC)

Weightlessness should end when the spacecraft experiences significant air resistance. With Mercury spacecraft reentering, something was set to happen when it got to 0.05g, which was well before the parachutes were deployed. Bubba73 06:17, 15 October 2021 (UTC)

These flights are just more expensive versions of the vomit comet flights that use parabolic flights in conventional aircraft to induce feelings of weightlessness. The only differences are 1) they use ballistic rockets rather than conventional aircraft to become airborne. 2) They cross the Kármán line, an arbitrary line that defines the "legal" outer edge of the earth's atmosphere for defining where "space" starts (there is no practical physical definition where one clearly leaves the earth's atmosphere and enters space). The two factors make for a more intense ride than the vomit comet, with longer periods of freefall, but it's a difference of degree and not nature in terms of the type of experience and the kind of flights these are. These are super expensive amusement rides, and not "space flights" in the normal understanding of the term. --Jayron32 14:56, 14 October 2021 (UTC)

October 15

Why plotting graph of voltage vs time instead of current vs time in Alternating current?

Why plotting graph of voltage vs time instead if current vs time in AC currents?

See this Google image results here, in most images graph drawn on voltage vs time not current (amps) Vs time. Why so? Rizosome (talk) 02:07, 15 October 2021 (UTC)

My WAG is that voltage is more fundamental than current, since the latter is dependent on the resistance. Clarityfiend (talk) 02:46, 15 October 2021 (UTC)

Not that wild a guess. The contractual obligation of electricity companies is to deliver voltage to their customers, not current. The standard in any country for the mains electricity also specifies the nominal supply voltage(s) (and frequency), which should be dependable, while the consumption and thus the current may fluctuate wildly and sometimes unpredictably.  --Lambiam 06:56, 15 October 2021 (UTC)

• It does not make much sense to say that current depends on resistance and voltage does not.

Simple electrical devices have a Current–voltage characteristic, that is a curve that imposes a relationship between the current and the voltage. Here, "simple electrical devices" mean anything with two wires popping out that does not rely on weird control systems; a nuclear power plant with fixed settings is "simple" but a LED with a cycling dimmer is not by this definition. In a simple closed circuit with two electrical devices (e.g. a battery and a lamp), you can determine what voltage/current exist in the circuit by simply drawing characteristics and finding the intersection point; you can think of it as the two devices "negotiating" a voltage-current point that is acceptable to both.

Most power supplies are designed to have an almost-vertical characteristic, i.e. have a stable voltage no matter the current. In that sense voltage does not depend on the load (resistance) applied, but it is a design choice of the power supply. (Arguably it is easier to design fixed-voltage sources for most electricity generation methods, but we can and do produce fixed-intensity power supplies used in some contexts.)

This design choice makes sense in most applications, because common electrical circuits are wired in parallel. (For good reason: in series, a fault in one element causes the whole circuit to break; you do not want your oven to go out if your toaster is broken, or if your neighbour’s toaster is broken, so both your home and the local grid are parallel circuits.) Parallel circuits are "stable" (in the sense that what happens in one branch of the circuit does not impact too much what happens in other branches) when the voltage is stable. Tigraan 09:29, 15 October 2021 (UTC)

Why is the Bee Hummingbird considered a dinasour?

The article of the says the Bee Hummingbird is considered a dinasour. But neither it’s entry of the linked entry explains how a living creature cane be a dinesour. -- Wis2fan (talk) 05:00, 15 October 2021 (UTC)

The article has been fixed. Birds are generally considered to be descendants of dinosaurs, but there are no living dinosaurs. ←Baseball Bugs carrots→ 05:19, 15 October 2021 (UTC)

False. Birds are avian dinosaurs. The non-avian ones died out. Imagine Reason (talk) 10:21, 15 October 2021 (UTC)

If you follow the modern scientific definition of dinosaur (see its first definition at Wiktionary), a dinosaur is any animal belonging to the clade Dinosauria, which includes the clade Ornithurae and thus all birds, including the bee hummingbird.  --Lambiam 06:44, 15 October 2021 (UTC)

In any case, even though the article is now fixed, the front page is still showing the dinosaur thing. ←Baseball Bugs carrots→ 07:05, 15 October 2021 (UTC)

The article says "In traditional taxonomy, birds were considered a separate class that had evolved from dinosaurs, a distinct superorder. However, a majority of contemporary paleontologists concerned with dinosaurs reject the traditional style of classification in favor of phylogenetic taxonomy."

Using the same reasoning, humans are fish. Now, that all makes sense from the point of view of a palaeontologist. It's a diachronic point of view, where phylogenetic taxonomy makes more sense. From a synchronic point of view, traditional taxonomy makes more sense. Humans are not fish, which are creatures with a spine and internal gills, and birds are not terrible lizards. They're nothing like lizards and, aside from a few flightless birds, they're less dangerous than a medium-sized dog. Certainly Sir Richard Owen, when coining that term in 1841, 18 years before publication of On the Origin of Species, adhered to a synchronic point of view and would not have not used that term if he had known that it would also be applied to sparrows.

Anyway, when measured in generations, all traditional dinosaurs may have been more closely related to each other than any of them was to any modern bird. PiusImpavidus (talk) 09:09, 15 October 2021 (UTC)

False. Fish are not a clade. Dinosaurs are. Therefore we're not fish, but birds are dinosaurs. Imagine Reason (talk) 10:21, 15 October 2021 (UTC)

If you consider dinosaurs to be a clade containing birds, then it would be consistent to consider fish a clade containing all other vertebrates (the tetrapods). But this confusion comes from using common names like "fish" that can be interpreted in various ways. Palaeontologists favouring a cladistic taxonomy use well-defined terms like Craniata and Gnathostomata that match to clades. Jmchutchinson (talk) 12:19, 15 October 2021 (UTC)

• So there are two problems here. There is the issue that there are casual, informal systems of classifying things that have developed through tradition over along time, and passed along informally through time. Under that system, our common language, it is usual to think of birds as NOT dinosaurs. However, when trying to classify things according to their genetic history (that is, what is related to what else, and what descended from what else), birds are clearly dinosaurs. Which is to say, that all moderns birds are descended from a single ancestor who themselves was clearly a dinosaur. The issue is whether it is useful to introduce that information into every article on every bird in a prominent way, or not. It isn't. Birds ARE dinosaurs, but sometimes it is less confusing not to mention it in a random article on a random species of bird. And actually, all fish do not belong to the same clade, unless you go back further than fish existed. Things we call fish like lancelets are not actually in the same clade as other fish. --Jayron32 12:32, 15 October 2021 (UTC)

Jayron, generally I agree but (1) there must be a typo in what you wrote: "Under that system, our common language, it is usual to think of birds as dinosaurs." You must have meant "not usual".

(2) You seem a bit adrift in saying that because lancelets are not in the same clade as other fish, fish is not a clade. Of course there are subclades, sub-subclades, etc. within the fish right down until the level of biological species, but that does not invalidate fish+tetrapods being a clade. More specifically, you say "other fish", which implies that you do consider lampreys as fish. Likewise, "hagfish" are evidently commonly called fish (the clue is in the name!). The group containing lampreys, hagfish, some other fish-like fossils and the Gnathostomata (other fish + tetrapods), form the Craniata (the vertebrates), which is believed to be a clade. So "fish" as considered in common parlance, lumped with the tetrapods, can be said to form a clade. Here is a tree, which often makes things clear when words don't. But if you consider that some of these other fish-like fossils are not fish, yet you consider lampreys are, then fish+tetrapods is indeed not a clade. If you exclude lampreys, hagfish and these fossils from fish, then you are left with Gnathostomata, which is a clade. Jmchutchinson (talk) 14:42, 15 October 2021 (UTC)

You'll notice that I had already fixed my mistake before you noticed it was a mistake. Your response was at 14:42, but I had already fixed the missing word at 13:56. --Jayron32 16:27, 15 October 2021 (UTC)

What percentage of Misplaced Pages readers are paleontologists? ←Baseball Bugs carrots→ 16:13, 15 October 2021 (UTC)

A small percentage, because there are not many palaeontologists in absolute numbers. However, a great many more people are sufficiently interested in the subject to be familiar with these matters (such as myself: I'm not a palaeontologist, but count one as a friend, have met several others, and attend or watch public lectures and read science news relating to the discipline). One needs to be paying some attention to the quite fast-moving developments in this field to be aware of the current scientific concensus, as opposed to the one being taught when we were at school. I dare say a reasonable proportion of Misplaced Pages readers do at least some of the same.

Our false perception of living birds or Avialae as not being dinosaurs is skewed by their not being any living non-avian (aka non-avialan) dinosaurs for comparison. But if one were to go back 66 million years, one would see a great many bird-like creatures: the average person would judge some to be birds and some not birds, but would often be mistaken – some they judged not-birds would actually be birds, and some they judged birds would be dinosaurs, but not birds. There would in addition be many dinosaurs that looked somewhat like birds, showing that birds were a group nested deep within the dinosaurs. Our 25-year-old, intensively edited article Origin of birds also speaks to this. {The poster formerly known as 87.81.230.195} 90.193.128.151 (talk) 19:31, 15 October 2021 (UTC)

The problem is that the dinosaur thing is just thrown in there, with no explanation or citation. ←Baseball Bugs carrots→ 20:17, 15 October 2021 (UTC)

Are you saying that none of that article's 145 citations are relevant to the issue?

How do you feel about the citations in the articles Origin of birds, Dinosaur, Evolution of birds, Bird, Feathered dinosaur, Theropoda, List of dinosaur genera, and even Human-dinosaur coexistence? {The poster formerly known as 87.81.230.195} 90.193.128.151 (talk) 22:57, 15 October 2021 (UTC)

Thank you, baseball bugs. You I can understand. -- Wis2fan

Today's featured picture is the Red-billed gull. How come there's nothing in its article about dinosaurs? ←Baseball Bugs carrots→ 12:28, 19 October 2021 (UTC)

According to biological evolution, was humanity the result of incest?

I know that incest, especially in first degree relatives (parents/siblings) and to a lesser extent in second degree relatives (cousins) can seriously case genetic damage and bodily malformations and serious physiological problems so if the first humans on earth where a sister and a brother born to the same parents and they had sex to create the first human nuclear family, how could it be that the family was healthy, survived and prospered in the rich, genetically dense (many animal types anywhere) and extremely dangerous nature back then? Thanks, — Preceding unsigned comment added by 49.230.134.86 (talk) 05:16, 15 October 2021 (UTC)

Don't confuse evolution with the Adam and Eve stories. ←Baseball Bugs carrots→ 05:20, 15 October 2021 (UTC)

Yes, that would be evelution. Clarityfiend (talk) 08:59, 15 October 2021 (UTC)

The answer is no. There is no reason to assume that the process of speciation that led to the emergence of Homo sapiens was genetically any different from that of other species, such as Camelus dromedarius or Danaus plexippus. While there are different driving mechanisms and it is not known for sure which one played a role in the genesis of modern humans, the common pattern is that a subpopulation of individuals of an ancestor species becomes genetically isolated from the rest of that species and so evolves independently, leading to its branching off from the ancestor species, which also keeps evolving but in different directions. The subpopulation at the root of the new Homo sapiens species may have been small, but was almost certainly not just a single breeding pair.  --Lambiam 06:24, 15 October 2021 (UTC)

Naturally, our species can be traced back to a Y-chromosomal Adam and a mitochrondrial Eve, but they lived hundreds of thousands of years apart or something. Imagine Reason (talk) 10:19, 15 October 2021 (UTC)

Careful! That is true of (more or less) only these two small parts of the genome, because neither the Y-chromosome nor mitochondria undergo recombination. In contrast, for the vast majority of our genome, the copies of the genes that we received from each parent are shuffled each generation; thus it becomes inappropriate to talk of a single common ancestoral individual. Jmchutchinson (talk) 11:49, 15 October 2021 (UTC)

I see, and yes, there was of course no First Human. Imagine Reason (talk) 14:46, 15 October 2021 (UTC)

• So, I think the OP is confusing incest which is a sociological taboo against sexual relations between close relatives, and there are well-documented hypotheses about a past Population bottleneck that caused a massive reduction in human genetic diversity at a point in our past, likely due to Inbreeding depression, also related to the Founder effect. It should be noted that inbreeding is NOT the same thing as incest; inbreeding occurs in any sufficiently isolated population, even if no "close relatives" are breeding with each other. I think the OP is thinking of one of the human population bottleneck hypotheses, such as the Toba catastrophe theory, among others. While these hypotheses and conjectures are well documented, they remain controversial. --Jayron32 12:25, 15 October 2021 (UTC)
• Think the human population bottleneck hypotheses pretty much covers the parent (ahem) post, Incest#Christian touches on the Biblical issue – "It is inevitable for Bible literalists to accept that the first children of Adam and Eve would have been in incestuous relations as we regard it today. However, according to the Bible, God's law which forbids incest had not at that time been given to men, and was delivered to Moses after Adam and Eve were created. " So that was ok. . . dave souza, talk 16:45, 15 October 2021 (UTC)

  Heck, if you take Adam and Eve seriously, you would be saying that humanity started with a man and his genetically modified, transgender clone. --Khajidha (talk) 21:18, 15 October 2021 (UTC)

I'd like to point out that there's no law against incest in Israel. Imagine Reason (talk) 03:11, 16 October 2021 (UTC)

What's your source for that claim? ←Baseball Bugs carrots→ 03:43, 16 October 2021 (UTC)

Possibly Misplaced Pages.--Shantavira| 08:21, 16 October 2021 (UTC)

Here's more detailed info: ←Baseball Bugs carrots→ 13:12, 16 October 2021 (UTC)

If the ancestry chart of any individual human is expanded for twenty generations, it is an almost certainty that one or more of these roughly one million ancestors was the issue of an incestuous copulation. In other words, without incest none of us would have been here. No bottleneck needed, and you don't have to go back more than 10 centuries.  --Lambiam 22:11, 16 October 2021 (UTC)

No widely available outdoors PCR test in NYC?

I know of one doctor's office that tests patients before procedures, and they do it on the roof. Other than that, AFAIK clinics and hospitals conduct tests indoors. Until recently, there were limited mobile testing sites that offered PCR tests, but they seem to have disappeared. Why is America so cavalier about indoor transmission? Imagine Reason (talk) 14:49, 15 October 2021 (UTC)

I'm confused as to why you think "America" is a synonym for "NYC". --Jayron32 16:30, 15 October 2021 (UTC)

I blame the Media. —Tamfang (talk) 01:33, 16 October 2021 (UTC)

New York is more conscientious about COVID than much of the rest of the country. Show me an American city that promotes outdoors testing. Imagine Reason (talk) 03:09, 16 October 2021 (UTC)

"Promotes" is iffy so I won't touch that. But it's trivial to find cities in the US where drive-thru (and from what I saw outdoor walk-up) testing is still readily available e.g. Orlando, Florida , El Paso, Texas (click on either one of City of El Paso Testing or City/UTEP Testing) / , San Francisco, California , Washington, D.C. . From what I saw at least two of these definitely offered PCR testing as an option.

Note even for testing at clinics etc, I'd hesitate to conclude without further evidence that this means the testing is indoors. In NZ AFAIK even before the recent outbreak, the norm was to get people to stay in their cars if they needed a test, or at least outside if they didn't drive and call for someone to come out and test. Of course the situation in NZ is and was fairly different, still the point is you cannot conclude without looking into the specific procedures for each site whether it's getting people to go into the clinic for testing or what.

Indeed I noticed a lot of drive-thru testing Walgreens on Google Maps etc, and so looking at their website it seems like all their testing is drive-thru with no walk-ups available "No, Walgreens is not equipped to perform walk-in testing at this time. Patients must arrive in a vehicle and are not permitted to exit the vehicle or enter the testing location." Funnily enough, I see a bunch of New York locations there and it seems like they do PCR testing. And I'm fairly sure some of them are within the boundaries of what is New York City e.g. 925 Soundview Avenue. So the basic premise of this question seems questionable, but whatever.

While I make no comment on the wisdom of what they're doing in New York City, I'd note that "more conscientious about COVID than much of the rest of the country" even when we put aside the seems irrelevant since New York City remains an extremely poor example to choose. NYC is noted as the most densely populated major city in the US where private vehicle use to get around is rare compared to much of the US, and even ownership is/was? under 50%. While New York City also has quite a lot of open spaces for a city of its density , still what works in other places may not be so easy in New York City considering the need is not only to test the person but get them there (e.g. if they're taking public transport).

Going back to the NZ example, most GPs in stand-alone or partly standalone buildings with their own entrances and exits etc, rather than in shopping malls or other large shared buildings so the procedures I mentioned earlier have generally be quite easy to implement. As always there is a percentage of the population for who it remains difficult especially those who don't drive and have limited or no access to mobile phones, still the difficulties are fairly different from trying the same thing in New York City.

Nil Einne (talk) 14:52, 16 October 2021 (UTC)

Some more research, I think many of the Walgreens examples are actually at drive-thru pharmacies so I guess the testing provider is technically indoors albeit with outdoors separating them and the testee. Anyway it seems CVS also offers drive thru testing at some sites albeit it sounds like some sites may be in store (but I'm not sure) so you probably need to look more carefully. Still when I looked at which is annoying since it won't let me view it from outside the US, there are some sites in New York with drive-thru testing. Many seem to be antigen testing, although it seems all lab test PCR (but not rapid PCR) are drive-thru. It's unclear to me if they have any option besides a rapid-test (and possible entering a clinic) for non drive-thru customers.

For the lab-test PCR, it says "Drive-thru test (vehicle recommended)". Whether that means they let you walk, or cycle, through the drive thru I'm not sure especially since other parts of their site seem to suggest you do need a vehicle for their drive-thrus. (And my understanding is liability insurance in the US means most stores hate it when anyone isn't in a motorvehicle in their drive.) Interesting they get you to perform the swab yourself which I find a bit weird, however I guess if the tester is inside the pharmacy access to the testee to perform a swab via the drive thru window is likely difficult. Also considering this is the heavily regulated US market I assume they have sufficient evidence self or untrained assistant swabbing performed under supervision works sufficiently for their purposes.

Searching found a number which I believe in New York City e.g. Ridgewood Covid - 19 Testing Site, 61-15 Metropolitan Ave; Bay Parkway - Brooklyn Covid - 19 Testing Site, 6831 Bay Parkway; Ralph Avenue - Brooklyn Covid - 19 Testing Site, 2320 Ralph Avenue; Avenue U - Brooklyn Covid - 19 Testing Site, 4112 Avenue U; Community Site Cvs 8940 - Westchester Avenue, 1688 Westchester Avenue; 10Th Avenue - Whitestone Covid - 19 Testing Site, 153-01 10th Avenue; Broadway - Passaic Covid - 19 Testing Site, 394 Broadway; Inwood - Burnside Avenue - Covid - 19 Testing Site, 530 Burnside Avenue; Jamaica Avenue - Bellerose Covid - 19 Testing Site, 251-21 Jamaica Avenue; Elmont - Dutch Broadway - Covid - 19 Testing Site, 1797 Dutch Broadway. To be clear, this list isn't exhaustive and I've excluded any in Staten Island.

Interesting enough, there are 2 rapid PCR test locations listed Community Site Cvs 10426 - New Rochelle, 505 New Rochelle RD and Community Site Cvs 2141 - Kings Hwy, 2925 Kings Highway. I initially assumed these two also drive thru locations given the confusing ability to book individual lanes. And their site also says "Yes. At our rapid testing sites, patients who receive a negative test result are able to enter the clinic for a visit with a MinuteClinic provider to discuss your results and other health concerns, and for further evaluation of symptoms." which I guess doesn't apply to PCR anyway since even rapid PCR is likely to be hours. But that made me think they make you stay outside without a negative result. However having taken a look at both sites on Google Maps, I don't see any sign of a single drive thru lane let alone four. So possibly the test is performed in doors and the lanes are in store lanes.

In any case there are still all the other drive thru lab test PCR sites which seem to affirm the basic premise of this query is questionable. Per my earlier comment I appreciate drive thru testing isn't an option for many in New York City. But that just re-affirms why it's such a bad location to chose to represent the US whatever their alleged conscientiousness. Since from what I can tell, much of the US, as with quite a bit of the world, have chosen drive-thru testing as their primary means for delivering out-door testing despite the obvious negative implications for de-carbonising economies. (Both for the added security of the car, but also allowing easier travel to the sites without needing to use public transport.) With walk-ups hopefully catered for but generally not the preferred means. And also easier to cater for when these are in locations not set-up for some specific use. (And these also tend to be easier to set-up when you can take over roads and carparks with limited concern for other businesses or users because of lockdowns.)

Nil Einne (talk) 16:51, 16 October 2021 (UTC)

As a probably final comment I'd note that the science on this is is continually evolving and so too are the conditions. If the evidence suggests something is relatively low risk compared to other risks, like being on a bus or train most people may experience prior to an activity, it may not be consider worth the cost e.g. in terms of reduced number of tests or other services that can be performed.

Getting infected with COVID-19 is undesirable and can be quite bad especially for the elderly and those with some pre-existing conditions albeit significantly reduced chance if fully vaccinated. But so too is dying from cancer or some other disease caught too late because your healthcare provider was too busy. Perhaps busy travelling on lifts all day to perform COVID-19 tests on patients to prevent the 0.25 chance they will infect someone else, having already infected 0.75 other people while travelling to get the test and 3.5 other people before they realised they were exposed and/or sick. (To be clear these are completely made up figures to emphasise the point why an epidemiologist analysing the evidence matters much more than the concerns of some random person on Misplaced Pages.)

Likewise what makes sense in one location e.g. with NZ again as an example where until very recently the goal was for absolutely no transmission and even now no transmission is still the overall albeit unachievable goal. This compares to the pretty much all the US including New York where it seems clear it's accepted some transmission is going to occur so the goal is instead to minimise it.

Nil Einne (talk) 17:21, 16 October 2021 (UTC)

Bronxville is not in the Bronx or the city but a few kilometers away in Westchester County, Elmont is not in Queens cause the address doesn't have dashy numbers, Passaic is in a completely different united state. The rest are in New York City (1688 Westchester Avenue is not in Westchester) Sagittarian Milky Way (talk) 03:08, 17 October 2021 (UTC)

For clarity, I didn't really bother to consider where those 2 rapid testing sites were (other than somewhere in New York state) since they don't seem to have any sign of drive thrus despite the confusing lane stuff. The rest yeah I assumed they were but was wrong. Nil Einne (talk) 16:29, 19 October 2021 (UTC)

It should be noted that drive through testing in New York City is likely less in demand than other places in the U.S. While cars exist in the U.S., New York has, by far, the lowest car ownership in the U.S. The majority of city residents do not drive at all, and it's even lower in Manhattan than in some of the outer boroughs like Queens and Staten Island. There just may not be the demand to support a large number of drive through sites, nor may there be the infrastructure (parking lots, open areas) to build impromptu drive-through testing sites as is done in most of the rest of the U.S. As means of data 55 % of New Yorkers own no car and of those that do, many still use public transportation for getting around the city. --Jayron32 16:44, 19 October 2021 (UTC)

Agricultural science

What is commercial Farming Advantage of commercial farming — Preceding unsigned comment added by 105.112.33.245 (talk) 15:24, 15 October 2021 (UTC)

What do you mean? ←Baseball Bugs carrots→ 16:04, 15 October 2021 (UTC)

If you mean industrial farming, economies of scale spring to mind. Clarityfiend (talk) 03:35, 16 October 2021 (UTC)

October 16

Are eggs created in the body of birds by stem cells?

What is the main type of cell in birds which makes the "genesis" of eggs?

Thanks, 49.230.20.227 (talk) 00:36, 16 October 2021 (UTC)

In birds, as in mammals, oogenesis proceeds from oocytes, specialized cells in the ovaries. The unfertilized egg (or fertilized but before embryogenesis has begun) itself is one cell.  --Lambiam 08:53, 16 October 2021 (UTC)

SI unit in Electro chemistry

If EMF and Voltage are not same, but why using same SI unit for both?

Volt is the SI unit of both the EMF and the voltage. Rizosome (talk) 05:58, 16 October 2021 (UTC)

Voltage is the unit for Electromotive force. ←Baseball Bugs carrots→ 07:04, 16 October 2021 (UTC)

In both cases the quantity can be defined as the amount of work on a test charge moving in an electric field, so they have the same dimension (specifically, M LTI). As you can read in our article Electromotive force, it can be measured in two-terminal devices as the voltage between the terminals, so naturally the same unit is used.  --Lambiam 07:37, 16 October 2021 (UTC)

Anti-Stokes %.

What are some examples of things that have a highest % of anti-Stokes? Like most emissions is like 95% Stokes, 5% anti-Stokes. What phenomenon have some of the highest percentage of anti-Stokes? 67.165.185.178 (talk) 12:16, 16 October 2021 (UTC).

Are you talking about Stokes shift? ←Baseball Bugs carrots→ 13:05, 16 October 2021 (UTC)

Plant identification

Hi, I have described these as "cycads". Can anyone just check and confirm this, or even provide a species or more specific type name? ITookSomePhotos (talk) 16:27, 16 October 2021 (UTC)

Aren’t these just small palm trees? Here they are described specifically as date palm trees.  --Lambiam 21:29, 16 October 2021 (UTC)

(edit conflict) I think jubaea chilensis or Chilean wine palm is a likely candidate. This article has a picture of a similar one growing happily on a traffic roundabout in London. Ventnor Botanic Gardens on the Isle of Wight has avenues of the things, according to this article, whose collection of Arecaceae have been given National Plant Collection status and says that warmer weather since the 1970s has made the island a good home for palms, most types of which normally struggle with the British weather. The most common palm seen here in southern England is the hardy Cordyline australis or cabbage palm from New Zealand, but these ain't they. Alansplodge (talk) 21:39, 16 October 2021 (UTC)

Silly me. I'll rename it. ITookSomePhotos (talk) 07:50, 17 October 2021 (UTC)

October 17

How a bird touching two wires would electrocute it?

I discovered that a bird touches two wires at once, it will create a circuit — electricity will flow through the bird and likely electrocute it.

How a bird touching two wires would electrocute it? I understand there is no ground between two wires, net potential differences is zero then how current flows through bird? Rizosome (talk) 02:41, 17 October 2021 (UTC)

Here's an explanation: ←Baseball Bugs carrots→ 05:46, 17 October 2021 (UTC)

It's very unlikely that two overhead electricity cables (assuming that's what you mean by wires) will be close enough for a bird to come in contact with both of them at the same time. But there is normally a big potential difference between adjacent cables (see Three-phase electric power) so they have to be kept apart so that the wind cannot cause them to come into contact and cause a short circuit.--Shantavira| 08:28, 17 October 2021 (UTC)

One suspected cause of the Roc becoming extinct, along with the decline of its preferred food. Clarityfiend (talk) 20:26, 18 October 2021 (UTC)

That must be how Popeye subdued the Roc in his voyage to see Sinbad. He sliced and diced the cooked bird into small nuggets and then opened a restaurant where one could buy a piece of the Roc. ←Baseball Bugs carrots→ 21:20, 18 October 2021 (UTC)

This YouTube clip shows a very large number of birds on power lines that apparently make a circuit when they all fly off at once (at 2:35). Perhaps several birds are close enough together that the current can jump the gap? Alansplodge (talk) 15:56, 19 October 2021 (UTC)

Tens of thousands to hundreds of thousands of birds are estimated to be electrocuted annually. Wildfires are sometimes started by electrocuted big birds catching fire (suggested web search: bird causes fire power line). A bird does not even need to touch two wires; flying close enough can make high voltage spark through air.

There indeed is a voltage difference between wires - otherwise what would be the point of having more than one wire. Distribution networks usually have at least two wires, though single-wire earth return installations exist mostly in remote areas.

There are a lot of things to unpack on this topic, depending how you imagine how things like "ground" work in electricity distribution. 85.76.79.135 (talk) 16:15, 19 October 2021 (UTC)

October 18

Inconsistency on Tesla Coil harming humans

I discovered that from wiki media, a Tesla coil producing high-frequency current that is harmless to humans, but lights a fluorescent lamp when brought near it. But here, it says Tesla Coil can harm humans. Which is correct? Rizosome (talk) 05:16, 18 October 2021 (UTC)

The risk is strongly related to the power output of the Tesla coil, and the frequency also plays a role. If the power is sufficiently low, a high-frequency Tesla coil will be harmless.  --Lambiam 06:35, 18 October 2021 (UTC)

A fluorescent tube requires very little current..--Shantavira| 08:30, 18 October 2021 (UTC)

• The OP's question is a bit like asking "I heard that getting shot with a bullet is harmful to humans, but I touched a bullet and didn't die". The level of harmfulness is dependent on the energy transferred. A fast moving bullet shot from a gun is much more dangerous than, say, the same bullet thrown lightly from your hand. In the same way, the amount of energy imparted by the tesla coil to a person will have a big effect on how harmful it is. --Jayron32 13:39, 18 October 2021 (UTC)

Switching from some genes to different ones as the organism matures

I know there should be a mechanism to activate some genes at certain stages of development. What is it?: AboutFace 22 (talk) 13:31, 18 October 2021 (UTC)

See Epigenetics and Regulation of gene expression for some introductions to the process. --Jayron32 13:37, 18 October 2021 (UTC)

October 19

What's the cause of short circuit in this circuit?

In electrical devices, unintentional short circuits are usually caused another conducting material is introduced, allowing charge to flow along a different path than the one intended.

If another conductor is introduced then it makes circuit series connection, then what causes short circuit? Rizosome (talk) 01:24, 19 October 2021 (UTC)

Who says it does? What circuit are you talking about? There's an infinite number of combinations. Give us something to work with. --OuroborosCobra (talk) 02:05, 19 October 2021 (UTC)

Ummm... the conductor you introduced? The conductor has a (relatively) low resistance so the current will bypass the intended path of the current - essentially taking a shortcut i.e. the "short" circuit. 41.165.67.114 (talk) 05:58, 19 October 2021 (UTC)

It says here Rizosome (talk) 02:29, 19 October 2021 (UTC)

That section does not mention a "series connection". The cause of a short circuit is always the appearance of a new low-resistance parallel connection in the circuit.  --Lambiam 07:49, 19 October 2021 (UTC)

Particle creation

In subatomic reactions which involve creation of particles, e.g. when stuff is smashed together at very high energies, is it known or believed whether the creation of these particles is truly instantaneous, or whether there is a finite (presumably incredibly short) formation period? — Preceding unsigned comment added by 2A00:23C8:7B08:6A00:F0CC:7064:9880:EDB7 (talk) 10:38, 19 October 2021 (UTC)

Such a thing may be unknowable. According to the uncertainty principle, certain measurable properties, known as Conjugate variables, cannot be simultaneously known to the same level of certainty. One of those conjugate pairs is "The energy of a particle at a certain event" and the " time of the event" that produced that particle are such a conjugate pair. If we know with high levels of certainty, the amount of energy of said particles, what we cannot know to any real certainty is when the event occured. It's not a technological limitation, it's baked into the mathematics of quantum physics. --Jayron32 17:13, 19 October 2021 (UTC)

Leibniz asserted that "no transition is made through a leap", and I suspect most physicists, including quantum physicists, also hold this to be true. The idea of truly instantaneous change involving some spatial extension is fundamentally at odds with the theory of relativity. And, inasmuch as particles are excitations of some field, they have spatial extension.  --Lambiam 18:53, 19 October 2021 (UTC)

October 20

Various types of honey

Living in the Western United States I purchase my honey at Amazon. It is collected in a Utah farm, It is a thick honey but this honey never crystallizes. Once upon a time I happened to travel to rural Utah for a reason different than collecting honey and in a small grocery shop bought a jar of honey. "Closer to nature" was my motivation. This honey crystallized two month after staying home. What's the difference between the two honeys? Is crystallized honey somehow not as good as the fluid one? Perhaps the one I purchase on Amazon is specially diluted with water to prevent crystallization? I feel there is a lot of mystery in my honey. Thanks AboutFace 22 (talk) 00:56, 20 October 2021 (UTC)

Our honey article talk about several factors that can affect crystallization, including the nature of the honey itself, temperature/handling, and addition of other ingredients. DMacks (talk) 05:34, 20 October 2021 (UTC)

Honey (a natural and inherently variable substance to start with) can be processed in various ways, resulting in greater or lesser tendencies to crystallize (which is in itself not a problem: gentle heating will re-liquify it). Such variations in honeys do not make one or another inferior, just different.

Our article Honey discusses this at Honey#Classification by packaging and processing and elsewhere. {The poster formerly known as 87.81.230.195} 90.193.128.151 (talk) 05:38, 20 October 2021 (UTC)

How to know if a certain food contans caffeine (or any similar substance?

Dry food / fresh food / liquid food,

Is there any way to find if the food contains any "detectable" amount of caffeine (preferably doable at home)? Thanks 2001:44C8:4200:4FF2:16EA:EFA7:4BD4:A829 (talk) 03:44, 20 October 2021 (UTC)

Relatively inexpensive (say $10-20) Caffeine Test Strip Kits (easily websearchable) can be purchased, but these are intended to check that "decaffeinated" coffees and teas do not have excessive caffeine levels, or to roughly measure caffeine levels in drinks that are supposed to contain it. They would probably not be capable of detecting traces of caffeine in other comestibles that ordinarily do not contain caffeine in significant quantities.

Kits for detecting caffeine in breast milk (which may reach levels of around 1% of the level in the mother's milk) are or have been also available, and might be usable on other liquids.

More sophisticated and sensitive tests seem to require laboratory-level equipment such as spectrometers. Perhaps other editors may know of other means. {The poster fomerly known as 87.81.230.195} 90.193.128.151 (talk) 05:26, 20 October 2021 (UTC)

"Detectable" is a question of how you choose to try to detect it--different methods have different lower-limit of detection. So an HPLC system might find a very low level (ppm), whereas a test-strip might only find a few tens of mg per serving-size. It's pretty easy to extract the caffeine from a few tea-bags or coffee-grounds using kitchen chemistry and materials from a local hardware store, and it's sensitive enough to find that different brands/styles of coffee have different content. But it is not easily generalized to "any food" (coffee is a fairly simple combination of chemicals) and obviously depends on how good a balance or scale you have. But if your goal is just "does it contain?" then you don't need to quantify, just observe. DMacks (talk) 05:49, 20 October 2021 (UTC)

Article Cited by Anti-Vaxxers as Evidence COVID-19 Vaccines Are Not Effective.

This article, Increases in COVID-19 are unrelated to levels of vaccination across 68 countries and 2947 counties in the United States seems to go against the scientific mainstream that COVID-19 vaccines are effective against the spread of COVID-19. Am I misunderstanding something? Has this article passed peer-review? A Quest For Knowledge (talk) 15:52, 20 October 2021 (UTC)

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