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August 26

Walden Farms

What exactly is in Walden Farms products that makes a whole jar of pancake syrup have zero calories? — Preceding unsigned comment added by 82.43.219.147 (talk) 08:48, 26 August 2017 (UTC)

Ingredients lists for all their products are available here. Rojomoke (talk) 10:07, 26 August 2017 (UTC)

Note that their "SAVE 10,000 CALORIES A MONTH" claim is highly suspect. According to some studies, using artificial sweeteners does not seem to actually cause weight loss. The reasons are unclear, but one possibility is that the perceived sweetness causes the release of insulin, which causes blood sugar to plummet, making you crave sweets. The other possibility is just that your body expects a certain number of calories per day (or specific constituents like protein, fats, and carbs), and if it doesn't get them from one source, it makes you feel like you are starving to death until you get them from another source. A more honest claim might be "EAT AN ADDITIONAL 10,000 CALORIES IN OTHER FOODS EACH MONTH !". StuRat (talk) 17:35, 26 August 2017 (UTC)

• Nothing with any calories.

Enough of a non-calorific gum to make some sort of viscous liquid or colloid, when mixed with water

Non-calorific sweeteners, such as sucralose

Concentrated flavourings

It's more of a food pill than a foodstuff, but it's calorie free and free from "those evil carbs". Andy Dingley (talk) 12:47, 26 August 2017 (UTC)

Note that the nutrition information these doesn't give an amount for even 100g, let alone a whole jar. It only gives an amount per serving and serving sizes are normally either 1/6 or 1/12 jar of a jar. So the zero calories only means it does not meet the minimum to have any calories in one serving. In any case since the syrups all seem to be flavourings, water, preservatives, ingridients to give the desired consistency and acidity and sucralose as the sweetener you should not expect many calories. Nil Einne (talk) 12:46, 26 August 2017 (UTC)

Feynman Lectures. Exercises. Exercise 12-5 JPG. Lecture 12

. .

...

12-5.* A side view of a simplified form of vertical latch is as shown. The lower member A can be pushed forward in its horizontal channel. The sides of the channels are smooth, but at the interfaces of A and B, which are at 45° with the horizontal, there exists a static coefficient of friction μ. What is the minimum force F that must be applied horizontally to A to start motion of the latch, if B has a mass m?

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

I have solved the exercise png, but I've found that if
${\displaystyle mg{\tfrac {1-\mu }{1+\mu }}<F<mg{\tfrac {1+\mu }{1-\mu }}}$, then
${\displaystyle \mu \neq {\text{const}}}$, with ${\displaystyle \mu =0}$ at F = mg.
How is it possible?
Username160611000000 (talk) 11:57, 26 August 2017 (UTC)

It seems that when motion doesn't begin the friction force rises until breakaway. Username160611000000 (talk) 12:52, 26 August 2017 (UTC)

That looks like a pretty complicated situation to me, and I'm not confident of an answer yet. The smooth walls are applying some kind of torque to the vertical element, with multiple forces to compensate for the tendency of the horizontal element to turn it. But what strikes me most is that if the joint is freely moving, the rear wall applies relatively little pressure -- but if it is stuck, then when you push in the latch, you must be putting considerable force on the rear wall. Does that make any sense? Wnt (talk) 15:42, 26 August 2017 (UTC)

See the Misplaced Pages article Wedge that describes the simple machine involved. B will move at the same speed as A so the mechanical advantage is unity (1). With no friction the force F is just the weight of A which is mg. The source of friction is the force normal to the surfaces in contact which is mg/√2. The force required along (i.e. in the slanting direction of) the surfaces to start them sliding is μmg/√2. The otherwise frictionless arrangement gives the pusher wedge no mechanical advantage in applying this force either. So my result is (1+μ)mg/√2. Blooteuth (talk) 22:14, 26 August 2017 (UTC)

is the force normal to the surfaces in contact which is mg/√2 -- ${\displaystyle N\neq {\tfrac {mg}{\sqrt {2}}}{\text{ , but }}N=mg{\sqrt {2}}}$. You can check that if you consider all forces, applied to member B. I have understood that magnitude of friction force varies like this . In ex. 12-5 as F grows, such a moment (namely F = mg) is possible when there is no parallel force. Feynman didn't say that, but correct formula for friction force is ${\displaystyle F_{\text{friction}}\leq \mu N}$. Username160611000000 (talk) 04:38, 27 August 2017 (UTC)

You can consider the balance of mechanical work when A moves by small distance ${\displaystyle \delta x}$. The work of the force (${\displaystyle F}$) applied to A is ${\displaystyle \delta xF}$. Due to the geometry B should move by the same amount - ${\displaystyle \delta x}$ - up, so work against the gravitational force is ${\displaystyle \delta xmg}$. On the other hand the surfaces of A and B will move ${\displaystyle {\sqrt {2}}\delta x}$ relative to each other. So, the work against the friction force (${\displaystyle F_{f}}$) is ${\displaystyle {\sqrt {2}}\delta xF_{f}}$. The friction force itself is proportional to the force that presses A against B or

${\displaystyle F_{f}=\mu \left({\frac {mg}{\sqrt {2}}}+{\frac {F}{\sqrt {2}}}\right)}$.

You should note that the pressure force is a sum of two terms (Blooteuth missed the second term). So we have the balance:

${\displaystyle \delta xF=\delta xmg+{\sqrt {2}}\delta x\mu \left({\frac {mg}{\sqrt {2}}}+{\frac {F}{\sqrt {2}}}\right)}$.

The final result is

${\displaystyle F=mg{\frac {1+\mu }{1-\mu }}}$.

So, no motion will happen if ${\displaystyle \mu \geq 1}$. Ruslik_Zero 18:47, 27 August 2017 (UTC)

Perception through yellow sunglasses

Yellow tinted sunglasses give the impression that there's more light (and that there's more contrast). Indeed, since they are filtering blue light, there is less light. What makes us feel there is more light and what makes us see more contrast? --Hofhof (talk) 16:24, 26 August 2017 (UTC)

Part of it is likely that the iris contracts or expands based on the light level detected. So, if less light gets past the sunglasses, the iris may expand to adjust for that. However, there seems to be another part, that blues and purples are seen as "dark" colors, perhaps because our cones and rods are less sensitive to them than "bright" colors. It would be interesting to know exactly what controls the iris/pupil diameter, and if that is highly sensitive to blues and purples. StuRat (talk) 17:26, 26 August 2017 (UTC)

Purkinje effect, Purkinje effect#Use of red lights, Adaptation (eye) Night vision#Biological night vision, Accelerating dark adaptation in humans. --Guy Macon (talk) 20:53, 26 August 2017 (UTC)

Monday morning, while waiting for darkness, I looked at the ground and was puzzled. The dead grass and the soil looked normal in color, and yet I found myself thinking that they ought not to be so yellow! Later I thought: when ambient light is so dim, I expect it to be blue, the color of twilight.  Maybe the Purkinje effect is related / was involved too? —Tamfang (talk) 05:52, 27 August 2017 (UTC)

August 27

Dumper railway cars in Hungary

Does anyone know, how these railway cars are called and what their exact function is? The photos are from Hungary, 1970.--Cameron Kay (talk) 11:15, 27 August 2017 (UTC)

" Fuel and building material Trade Company No. 11 plant, quarry terminal, Polish sweeping machine. Fortepan"

I don't think they are "dumper cars". They look more like typical European general use steel-body railway wagons, with central side doors and a flat floor. The yellow machine is an unloader for them, with conveyors either side. Presumably it has some shovelling mechanism in the middle that empties the wagons, rather than doing it by hand. Neat idea, as it saves building special wagons or facilities for them to unload at.

I'm guessing the load is brown lignite coal? The sort of thing that might well be bunkered in simple piles like this. Andy Dingley (talk) 12:25, 27 August 2017 (UTC)

(Edit conflict) The title of these images machine translates to "Budapest XVIII., Plant and Building Material Trade Company No. 11, Pebble Mine Terminal, Polish Screeding Machine."

The rolling stock resembles the "Czech (ČD) twin-axled open wagon of UIC Type 2", shown in our Open wagon#UIC standard goods wagons. At first glance, the second photo might seem to show the lids of a wagon with opening roof, but those are actually the paddles of the screeding machine, which pushes the goods toward the doors and onto the conveyors. -- ToE 12:36, 27 August 2017 (UTC)

So to address Andy Dingley's question, from the appearence of the aggregate material (smaller, more similarly sized pieces than likely for coal) and the translated caption (...Pebble Mine Terminal . . .), this is likely stone ballast being stockpiled for use on the railway network. {The poster formerly known as 87.81.2130.195} 90.204.180.96 (talk) 16:22, 27 August 2017 (UTC)

Is it possible to speak chimpanzee if one is raised by a chimpanzee or a group of chimpanzees?

I know there were attempts at trying to raise chimpanzee babies as humans, which failed. What about the reverse? Has anybody tried letting a human baby be raised by chimpanzees and see whether the child will speak chimpanzee better than human language? 50.4.236.254 (talk) 20:12, 27 August 2017 (UTC)

Research into possible Great ape languages didn't really start until well after we stopped using babies for bizarre and ethically "questionable" experiments. Ian.thomson (talk) 20:16, 27 August 2017 (UTC)

A human child wouldn't survive - they are just not born with the same survival skills as a baby chimpanzee, and do not develop quickly enough. For example, they wouldn't know how to cling to the mother while she runs. Wymspen (talk) 21:17, 27 August 2017 (UTC)

Note that all indications are that chimp language is rather limited. They're not going to be able to say "I saw 28 gorillas at the mountain pass three days ago", for example. Adult humans are capable of learning the limited language chimps do have, when they say things like "I'm angry !". StuRat (talk) 21:30, 27 August 2017 (UTC)

Supposing a group of chimps would even allow a non-chimp into their group, trying to do so deliberately would be a gross violation of human rights, and probably illegal most anywhere. ←Baseball Bugs carrots→ 21:38, 27 August 2017 (UTC)

They will make chattering noises apparently, but that is not really a language.--Shantavira| 08:00, 28 August 2017 (UTC)

Also of note is that most if not all of those stories are legends, those children were usually raised by human parents then abandoned (including for developmental issues, but otherwise, the isolation and/or mistreatment imposed by the parents often results in life-long developmental problems). —PaleoNeonate – 08:23, 28 August 2017 (UTC)

See Feral child. 92.8.219.206 (talk) 13:20, 28 August 2017 (UTC)

Virus surveillance

I know that there is ongoing surveillance for new viruses, and can find general overviews like . But I'm not sure how to apply it for a specific scenario. With recent news I find myself wondering, ever more seriously, whether a country like North Korea or simple bad luck might have released a virus that causes insanity, some kind of generalized, slow, progressive brain damage that leads people to act like ... the protesters and counter-protesters and politicians we have today. Any suggestions how would I go about trying to find out whether it is known what new viruses out there that have no obvious ill effects but are gradually working their way through the population, and whether there is any evidence they might linger at low levels in the central nervous system? Wnt (talk) 21:06, 27 August 2017 (UTC)

Toxoplasmosis is one vector candidate. According to our article: "Up to half of the world's population is infected by toxoplasmosis but have no symptoms". See "Crazy cat lady syndrome". See Toxoplasmosis#Rodents for some of the behavioral changes they cause there. The concern is that humans may also be susceptible to these type of changes. See Toxoplasmosis#Research for some of the mental effects on humans. The disease itself doesn't appear to be new, but perhaps some strains of it are (which conceivably could be the ones that affect human behavior the most). StuRat (talk) 21:15, 27 August 2017 (UTC)

It is curious to note that Toxoplasma discriminates by blood type; there was a postwar outbreak in Japan where blood type personality theory has been at times embraced, though I'm not sure the details line up. Wnt (talk) 18:14, 30 August 2017 (UTC)

While not disagreeing with the theoretical possibility of what Wnt proposes, my readings of accounts of politics and society in Ancient Rome and Greece (for example), suggests that "the protesters and counter-protesters and politicians we have today" are behaving no differently than such people did 2 millennia ago, or in the intervening centuries since. {The poster formerly known as 87.81,230.915) 90.204.180.96 (talk) 17:46, 28 August 2017 (UTC)

Indeed. A reading of the two greatest history books of all time, Gibbon's Decline and Fall of the Roman Empire and Macaulay's The History of England from the Accession of James the Second, should thoroughly cure one of such illusions. Looie496 (talk) 18:54, 28 August 2017 (UTC)

Potentially, this might not be the first time such an outbreak has occurred... Wnt (talk) 18:14, 30 August 2017 (UTC)

Borna disease virus (BDV) is one virus that may fit your criteria, it seems psychiatric patients have a higher incidence of anti-BDV antibodies perhaps suggesting a link. Eppstein-Barr virus may contribute to some cases of Parkinsonism and Lewy body dementia. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4713712/ lists several others. None of these would be regularly screened for in the general public. Generally a nucleic acid test (NAT) or antigen specific antibody test is used to detect the presence of a viral infection. Latent viral infections are difficult to detect, even more so for viral infections in the CNS. The CDC's emerging disease page is probably your best bet for finding out about new viruses https://wwwnc.cdc.gov/eid/. As for your grand theory, it's undeniable that viral infections of the brain exist and go unnoticed while causing behavioral changes. That said I strongly suspect that the vast majority of the behavior you have characterized is completely unrelated to viruses. The modern world is highly ordered and probably less violent and insane than any time in human history.204.28.125.102 (talk) 00:18, 29 August 2017 (UTC)

This is by far the most interesting answer, though the increased incidence seems uncertain. The work with these viruses seems recent enough that I still lack confidence about what is being missed... Wnt (talk) 18:14, 30 August 2017 (UTC)

If North Korea starts a mass immunization program then we should start to worry. I've suggested here, that the main threat from a bioweapon deployed by North Korea is probably not going to be a newly designed virus, rather a large number of different pandemic flu viruses. There have been such viruses created in the lab starting from a viruses that lack the capability to spread from person to person. So, this is proven technology not science fiction, so nothing would stop North Korea from developing a cocktail of a large number of such viruses. We can deal with a single SARS epidemic, a single Swine flu epidemic, etc. etc. but we probably cannot deal with hundreds of such epidemics at the same time. Count Iblis (talk) 02:04, 29 August 2017 (UTC)

@Count Iblis: North Korea already does mandatory vaccinations. I doubt its inhabitants ask many questions about what might be in those. I would hope (but doubt) that countries like the U.S. might collect sera from North Korean defectors and see what they light up, just to get an idea of what might be coming.

The flu is sort of a digression, but one of my old ideas from the 90s was the Doomsday Duck. Basically, V(D)J recombination, with flu alleles in place of immunoglobulin domains, in context of some sialylation or glycosylation-deficient bird, activated in differentiating enterocytes; maybe toss in some RTase, a primer, homologous recombination to keep things interesting. Back then this would have been difficult to make. However, by now I've seen at least three different well-thought out ideas for broad-specificity flu vaccination, so I'm reasonably hopeful by now that it could all be vaccinated against if the bureaucrats were ever blasted out of the way, though the ecological impact would still be devastating. Wnt (talk) 18:14, 30 August 2017 (UTC)

August 28

Could a non-cooling planet with 100% water clouds rain everywhere at once?

Wouldn't convection prevent 100% the surface area raining at the same time? Could more complex systems like, I don't know, cloud layers of different chemicals allow the surface to always be raining something? Sagittarian Milky Way (talk) 00:40, 28 August 2017 (UTC)

Not sure what you mean by a "non-cooling planet". The only problem I see with continuous precipitation everywhere on a planet is that it implies very little sunlight making it below the rain to drive evaporation, which of course is a critical portion of the water cycle. However, other heat sources could drive the system, such as tidal heating from a large nearby body, radioactive decay, or residual heat from formation. The last two would require either a somewhat young planet or one somewhat larger than Earth, in order to be significant enough. The tidal forces could work on a smaller body, though, such as a moon of a Jovian planet. As to the form of the precip, some might very well be snow, say during night or near the poles. It would be difficult to imagine a situation where the temp is always in the narrow range for liquid water, throughout the atmosphere. A planet entirely covered by ocean seems most likely to provide sufficient evaporation to drive planet-wide continuous precipitation.

As for convection, you might get a planet covered by hurricanes, and that does imply brief rain-free areas as the eyes pass over. However, sufficient winds like our jet streams might keep them from forming eyes, leaving you with a planet full of continuous tropical depressions. StuRat (talk) 01:40, 28 August 2017 (UTC)

If it's cooling while 100% humidity it could perhaps rain everywhere at once right? i.e. after an asteroid hit so big the hydrosphere boils. Sagittarian Milky Way (talk) 02:13, 28 August 2017 (UTC)

Yep, that could do it. I wonder if a supervolcano could, like the ones we've had on Earth. StuRat (talk) 02:49, 28 August 2017 (UTC)

Hairy ball theorem prohibits a ball system from having continuous non 0 wind speeds everywhere on the planet . your190 (talk) 19:55, 28 August 2017 (UTC) — Preceding unsigned comment added by 100.35.203.180 (talk)

• If "everywhere at once" means anything definite, it means that every single point on the planet is being struck by water at every single moment in time. Obviously that isn't going to happen, but equally obviously that isn't what you had in mind. If you don't give a more precise definition, though, the question has no answer. Looie496 (talk) 02:25, 28 August 2017 (UTC)

"The entire surface (non-gaseous planets) or 101.325 kilopascal surface (gas giants and mini-Neptunes) is at one moment in time being hit by a sufficient amount of 0.02+ inch liquid drops per square meter per second that if it was water Earth metrologists of the early 21st century would define it as rain. (or rainier)" This does not imply that said condition continues for tens or hundreds or thousands or millions or billions of years (though that would be really cool). Sagittarian Milky Way (talk) 03:19, 28 August 2017 (UTC)

I do not think that it is possible. For rain to form wet air needs to ascend to a height where due to adiabatic cooling its humidity exceeds 100%. However the air also needs to descend somewhere. In these downdrafts the air will warm and its humidity will decrease below 100% thus preventing raining. So, I think it is impossible for more than about 50% of the surface area to have rain at the same time. Ruslik_Zero 18:49, 28 August 2017 (UTC)

There could still be rain, formed at the higher altitudes, falling with the descending air. If the rain evaporates on the way down, then that's virga. StuRat (talk) 20:04, 28 August 2017 (UTC)

• I immediately thought of the hairy ball theorem, but it's not relevant here. The water is falling through three-dimensional space, not blowing acrost a surface. The rain will stop when it hits the surface, but in the meantime there is no reason why the motion of any one drop should interfere with another.

Visualize a water balloon exploding in free fall, spraying drops in every direction equally. Now run the tape backwards. Basically, you've got "rain" converging from every direction back onto the original sphere. Whether the conditions would ever exist to fulfill the OP's thought experiment is one thing, but the hairy ball theorem is not a cucumbrance in this case. μηδείς (talk) 15:31, 29 August 2017 (UTC)

WP:Reference desk/Miscellaneous#Architecting or Engeniering

August 29

Frequency dependent amplification?

In case of amplification of alternating current by a transistor, is the amplification dependent on the frequency of the source?Sayan19ghosh99 (talk) 01:13, 29 August 2017 (UTC)

Yes. Transistors have frequency limits. If you are working with audio or power, you can pretty much ignore this, but get into radio frequencies and it becomes important, get into microwave frequencies and everything changes, and by the time you light frequencies even the wires that connect to the transistor cannot transmit a signal. --Guy Macon (talk) 02:16, 29 August 2017 (UTC)

Although there's also the issue of Q, considered very simply as a ratio between the signal bandwidth and the carrier frequency.

For audio work, these are comparable frequencies - the bandwidth might go from near zero to a few 10s of kHz. Old analogue phones with carbon mics were just 300Hz–3.3kHz. For AM speech radio though, you might have a similar bandwidth but on a signal of around 1MHz. So although at higher frequencies the transistor's bandwidth might become seriously limited as a fraction of the carrier, that could also be far more than the bandwidth that the signal requires, so the design problem becomes relatively simple (if you have MHz transistors, then modulating an audio signal onto that isn't a big deal).

Back in the early days (1960s) of transistors with physically large junctions, even good audio design could be a problem as the transistor gain was rolling off noticeably within the bandwidth of the signal. Amplifiers were designed to require less gain than this, and to use negative feedback as a control mechanism instead of being simply gain limited, but even so they might run out of gain at the top end, because the raw transistor could just no longer achieve it.

Spread spectrum radio changes this simplification. RF circuits now need massive linear bandwidth as a proportion of their carrier, because the bandwidth used becomes so broad - far in excess of what the simple modulating signal might suggest. So they can become a difficult design problem.

In radio there's also the related, but distinct, issue of the linear amplifier. Is the transfer function of the amplifier linear across a range of signal powers? Now that's not needed for FM modulation, as transmitter power remains constant as the signal is modulated in frequency (but it needs your original point to be stable). But for AM (or SSB) modulation, the amplifier must also remain linear in response as the signal amplitude changes. This makes a crude FM transmitter often easier to design than a crude AM transmitter. Andy Dingley (talk) 09:48, 29 August 2017 (UTC)

In a bipolar junction transistor, the internal capacitance of the junctions causes gain to decrease with increasing frequency. See Gain–bandwidth_product#Transistors. A transistor's current gain between the cutoff frequency at which the current gain drops by 3 decibels and the transition frequency f_T can be estimated by dividing f_T by the frequency. Blooteuth (talk) 10:45, 30 August 2017 (UTC)

While shepherds didn't watch their flocks by night

Absent humans who might induce them to stay awake, will sheep generally graze at night? Iberia Airlines Flight 062 crashed at 10:02 PM and killed a flock of grazing sheep; I don't suppose shepherds were that common in England by the 1960s, so the idea of a flock autonomously feeding at 10PM sounds rather odd. Nyttend (talk) 04:55, 29 August 2017 (UTC)

Sheep grazing at night seems unlikely to me, this is confirmed in the sheep article. My understanding of flock animals such as sheep is that they congregate at night (possibly for added protection) and this fact would account for the large number of sheep killed. My assumption is that grazing sheep would be more separated and the strike rate would have been lower. Richard Avery (talk) 07:15, 29 August 2017 (UTC)

Agreed - the cited source uses the phrase "grazing sheep" but I suspect this is just shorthand for "sheep on a hill", who would have been grazing it during the day. Sheep also have a tendency to move uphill at night (see here), another strategy against predation. AndrewWTaylor (talk) 07:53, 29 August 2017 (UTC)

We don't need to repeat the Fernhurst Society's error in our article, so I'll remove the word. Dbfirs 06:06, 30 August 2017 (UTC)

Aural boxing?

What exactly is the "aural boxing" technique described in Cessna 188 Pacific rescue? 2601:646:8E01:7E0B:84FD:477A:71AB:7A1E (talk) 08:33, 29 August 2017 (UTC)

It's described here. Basically, it involves flying just on the edge of VHF radio reception. Because VHF radio is high frequency, it's more or less line of sight - this means that when the plane slips over the horizon, you lose contact. With a bit of geometry, you can then work out how far away the other plane is. The rescue plane flew in a kind of ⋉-pattern, and by tracking where it made and lost contact, it was able to triangulate where the Cessna was. Smurrayinchester 09:07, 29 August 2017 (UTC)

(It's called aural boxing because a) you're drawing a box around the target plane, and b) you're using voice radio and you have to keep talking constantly to avoid radio silence) Smurrayinchester 09:08, 29 August 2017 (UTC)

Thanks! 2601:646:8E01:7E0B:84FD:477A:71AB:7A1E (talk) 05:05, 30 August 2017 (UTC)

LM317 - conceptual difficulty

"the device is conceptually an op amp..." is it just me or is this bit (and the explanation that follows it) a bit misleading? First, the equation is different for a real non-inverting opamp amplifier (the feedback resistor is in the numerator), and second, an opamp does not work by "adjusting (...) the voltage of the output pin to be a fixed amount (!), the reference voltage, above that of the adjustment pin" , it adjusts the current through the feedback resistor to minimize Vdiff between both inputs, in other words both resistors carry the same current and the output voltage is Vout=Vin*(1+Rf/R1), thus the output is Vout-Vin=Vin*(Rf/R1) above (either) input.
I see how it's tempting to conceptualize the LM317 as a high-ampacity opamp that just amplifies the 1.25 reference voltage applied to a (non-externalized) non-inverting input, but the analogy seems faulty (why are the equations different?). At the same time, as a hobbyist, I don't know what is wrong with the analogy or where exactly it breaks down 78.53.240.75 (talk) 11:11, 29 August 2017 (UTC)

The LM317 sense/feedback input is a preconfigured OP amp. Configuring its output voltage is calculating a voltage divider of two resistors, matching the prefered output divided ratio the internal reference in addition to the power consumption of the LM317 as it does not touch the ground reference potential. The higher the voltage divider is, the more will the output modulated by the internal power consumption, rising the voltage drop of the lower resistor of the voltage divider. For recommended values and calculations, refer the manufacturer's datasheet. --Hans Haase (有问题吗) 11:33, 29 August 2017 (UTC)

the equations are different, though. There's something wrong with the analogy. I'm not arguing that the LM317 wasn't, at some level, an opamp, - most circuits that implement some kind of servo loop are one or contain one. 78.53.240.75 (talk) 11:41, 29 August 2017 (UTC)

here's how to get 5V from an opamp and LM317:

                           720                                                           
                           ___                                                      _____        
                        |-|___|--|                                                 |     |       
                        |        |                                   12V ----------|LM317|---|-
                 240    |        |                                                 |_____|   | 
                 ___    |  |\    |                                                   |       | 
             ---|___|---|--|-\   |                                                   |       | 
             |             |  >--|                                                   |      .-.
            ===         ---|+/                                                       |      | |
            GND         |  |/                                                        |      | | 240
                        |                                                            |      '-'
                     + ---  1.25V                                                    |       | 
                        -                                                            |-------|    
                        |                                                                    | 
                        |                                                                   .-.
                       ===                                                                  | |
                       GND                                                                  | | 720
                                                                                            '-'
                                                                                             | 
                                                                                            ===
                                                                                            GND

see what I mean? 78.53.240.75 (talk) 12:07, 29 August 2017 (UTC)

See DS LM317 Chapter 8.2 internal block diagram, which draws a voltage follower which is the classical full coupled servo loop. Is think: YES! --Hans Haase (有问题吗) 12:14, 29 August 2017 (UTC)

This discussion belongs at Talk:LM317 where I shall express agreement with User 78.53.240.75. Blooteuth (talk) 13:13, 29 August 2017 (UTC)

Thank you! When it occurred to me the equations were different, I thought "huh?!" 78.53.240.75 (talk) 17:38, 29 August 2017 (UTC)

August 30

Today's featured picture of moss

In today's featured picture of moss, the green chloroplasts appear to be within an otherwise green cell. Is that because the photo is capturing green coloration from the chloroplasts of many layers of cells deep to the superficial layer? Or are there chlorophyll particles also within the plant cell cytoplasm. DRosenbach 00:54, 30 August 2017 (UTC)

The image I have added seems to show chloroplasts at least two organelles deep in places, with the ones in back out of focus, making it appear to have a green background. And chlorophyll is not so much a particle as a pigment molecule with a very definite structure embedded in a complex matrix. μηδείς (talk) 01:05, 30 August 2017 (UTC)

chess and reasoning power

Does playing chess require much reasoning power? — Preceding unsigned comment added by Uncle dan is home (talk • contribs) 03:28, 30 August 2017 (UTC)

No, though it helps if one doesn't want to lose constantly. Ian.thomson (talk) 03:31, 30 August 2017 (UTC)

See here: "In a November 2006 match between Deep Fritz and world chess champion Vladimir Kramnik, the program ran on a personal computer containing two Intel Core 2 Duo CPUs, capable of evaluating only 8 million positions per second, but searching to an average depth of 17 to 18 plies in the middlegame thanks to heuristics; it won 4–2." And note that a laptop is not powerful enough to simulate the brain of a spider in real time. Count Iblis (talk) 03:57, 30 August 2017 (UTC)

• I, for one, wish to welcome our new spider overlords.... μηδείς (talk) 04:02, 30 August 2017 (UTC)
  • It doesn't need much reasoning power to be able to play a legal game of chess. It needs significantly more, however, to play well. Of course reasoning power is not all of it, too; you need strong pattern recognition as well, for one. Mind you, I would consider the spider comparison of Count Iblis rather irrelevant, because chess programs are in essence one-trick ponies, which living organisms obviously are not. And while humans do lose to top computers, I have to wonder how much of it is due to the fact that humans get tired and blunder on occasion, as famously happened during the particular match he cites. Double sharp (talk) 04:53, 30 August 2017 (UTC)

See Chess#Strategy and tactics for a description of the reasoning required in chess. Blooteuth (talk) 09:30, 30 August 2017 (UTC)

Tamping/ramming tool

Hello all, I'm about to put my pilot plant into operation, but there's one thing I still need -- a sturdy tamping/ramming tool, with its business end at least 1 inch but no more than 1.25 inches in diameter, and with a handle at least 2 feet long (for repacking the catalyst bed). The problem is, I don't know the correct name for such a tool, much less where to find one. Thanks in advance! 2601:646:8E01:7E0B:84FD:477A:71AB:7A1E (talk) 05:10, 30 August 2017 (UTC)

It sounds like you're describing a 1" diameter metal rod. Something like this: https://www.onlinemetals.com/merchant.cfm?pid=15291&step=4&showunits=inches&id=1114&top_cat=60 obviously can be had in other metals if aluminum is a problem.2602:306:CF32:13A0:9C44:6B42:8646:43CF (talk) 05:32, 30 August 2017 (UTC)

I don't think they make espresso tampers that small (I've seen 49mm and maybe they go a little smaller) but if you do a web search, it might give you some ideas. 173.228.123.121 (talk) 07:23, 30 August 2017 (UTC)

The name of the tool is a tamp or tamper, see Tamp. Blooteuth (talk) 09:16, 30 August 2017 (UTC)

It sounded like a cannon to me! Those ones are called ramrods. Dmcq (talk) 11:02, 30 August 2017 (UTC)

hurricane water

The first thing that comes to mind about hurricanes is enormous amounts of water falling out of the sky, causing flooding, etc. If that water is essentially rain (i.e. condensed from vapor) it should be relatively pure and drinkable, right? And in that case, why are people sending bottled water to Texas? Or is the hurricane water actually mostly sea water sucked up into the cyclone over the ocean and then dropped onto land? And if it's that, does it mean that any agriculture areas it fell on are now salted? Thanks. 173.228.123.121 (talk) 07:28, 30 August 2017 (UTC)

"Hurricane water" over land is mostly rain (on a ship at sea level, spray may play an important role). But rainwater isn't necessarily pure nowadays (it goes through the atmosphere, which is full of crap we release into it - see e.g. acid rain), and most people are not prepared to safely catch and use rainwater. Moreover, even if rain water is pure enough for drinking immediately, it is very hard to avoid contamination, which could lead to bacterial growth and disease quickly. Even if these risks are low at a personal level, they are significant from an epidemiological point of view. Remember - there are nearly 7 million people in the Houston Metropolitan Area. If only 1% of them catch a water-borne disease, and 1% of these die, the death toll will be 700 - or about 20 times the current estimate. --Stephan Schulz (talk) 08:20, 30 August 2017 (UTC)

• In any flood, pretty much the first thing that happens is the sewers become overloaded and spill out. Flood water is contaminated with all kinds of nasties - human waste, animal manure, fertilizer, rotten food (our article Social effects of Hurricane Katrina mentions that one problem was that raw chicken and shrimp got washed into the water table, leading to E coli outbreaks). Collecting rainwater and keeping it pure is difficult at the best of times (see water butt for some of the challenges), and I don't know how you could collect enough drinking water for a family in the middle of a storm. Smurrayinchester 09:40, 30 August 2017 (UTC)

I'm not sure that most of the water is fresh - see storm surge. At the very least it will be brackish. Matt Deres (talk) 13:47, 30 August 2017 (UTC)

Can see where the OP is coming from. The rain itself may be drinkable but the flood water is not homogeneous rain water. Stuck in such a situation one might just take a mouthful of an infectious dose. Personally, I think the bottled water being distibuted, should be further sanitized with 50/50 dose of a either Mezcal, Tequila or bourbon. But that is just my opinion. Yet, I think that there are many hundreds of wet people just now, that would agree with me. Donald – are you listening? Aspro (talk) 15:54, 30 August 2017 (UTC)

As for setting up a rainwater collection area (basically a funnel leading to a tank), there are 3 possible situations:

• During the worst part of hurricane, collection is not possible, as winds would knock it all down.

• Before and after the worst part, collection might be possible. However, the rainwater collected before would need to be moved some place safe so it doesn't get knocked down during the hurricane.

• After it's all over, there may not be any rain at all.

So, there may be some windows where collection is possible, but people may be too busy trying to make other preparations before or search for survivors after to collect rainwater. Some type of automated system that's battery powered and can deploy and retract the funnel based on wind speed and rain would be ideal. Any collection apparatus would need to be high up, like on the roof, to avoid contamination from splashing ground water.

I wouldn't be concerned about air pollution, as any in the air initially will soon be cleaned out by the massive rainfall, and factories typically shut down well before a hurricane hits, so the amount in the air should be less for that reason, too. StuRat (talk) 16:11, 30 August 2017 (UTC)

What do you mean wouldn't be concerned about air pollution? There is so much contamination of H₂O vapor in Hurricane Harvey that it has been precipitating out to such a degree, that it affords people, (whom are normally accustomed to one shower per day) , to a full 24 hour bath. Talking of baths, One tale I never understood, was about two nuns in a bath and the first one says "Where's the soap"; the second one replies "Yes it does, doesn't it" Aspro (talk) 19:07, 30 August 2017 (UTC)

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