The frequency of the white light

Question: A white light, as we all know, is composed of seven lights VIBGYOR. Each of the component lights has distinct frequency ranging from one value to another. So, when the photons have wavelength of 600 nm it becomes a yellow light and when it changes to 700 nm it becomes a red light. So, does this imply that the frequency with which a group of photons vibrate determine the colour of light? Well, in that case, with what frequencies are photons vibrating for a white light?
Comment: Actually, no, we do **not** know that.  The definition of "white" is quite different, and depends on whether you're talking about photopic (human eye) response or uniform frequency densities analogous to "white noise" in acoustics.
Comment: Almost duplicate; at least highly relevant:http://physics.stackexchange.com/q/78933/26076
Comment: "White light" can also be seen as equal proportions of red, green, and blue light (you don't need 7 colors).  This is why there are only three phosphor colors on a TV screen.
Answer: To get a perception of a white light, one has to observe simultaneously many photons having different frequencies and obeying a certain distribution function.
Keep in mind that a color is not a physical property, since it is resulted from human brain's interpretations of signals coming from eyes receptors.
Comment: Well, in that case, when a photon is simultaneous cycle of vibrations in different frequencies, doesn't that give rise to certain cases like induced action just as in Laser action ?
Comment: I did not get what you have said
Comment: What I meant to say was that if several photons are under simultaneous cycles of oscillation, wouldn't that result in generation of induced actions just like that in production of laser? Won't that creat a new form of electromagnetic radiation?
Answer: Light that our eyes, or other system of detectors, would perceive as "white" could have several different maekups:

It could be a stream of photons all in different energy / momentum eigenstates. That is, there could be a population of photons, some of which are red wavelength, some blue, some green and so forth as in freude's answer; OR
It could be made up of photons all in exactly the same quantum state. You really can have one, lone, sole "white" photon all on its own. A photon, like any other quantum object, can be in a pure quantum superposition of basis eigenstates (eigenstates of whatever observable you care to work with). There is no reason why a photon has to be in a pure energy / momentum eigenstate. Its state could be such that there is a complex amplitude $\psi(\nu)$ to be observed at wavelength $\nu$. For more information about this idea, see my answer to the following question How can we interpret polarization and frequency when we are dealing with one single photon?
Comment: Huh?  A single photon has a defined wavelength. How will that be white?  Alternatively- any photon absorbed by a rod rather than a cone will be interpreted as "white" because rods are frequency-insensitive.
Comment: @CarlWitthoft No it doesn't: a photon with a single wavelength is in an energy eigenstate. It doesn't *have* to be so, just as an electron doesn't *have* to have a well defined position (*i.e.* an electron doesn't have to be in a position eigenstate). Have a look at my other answer. If a photon were prepared so that it was in a superposition of energy eigenstates, and it coupled with a whole mass of red / green/ blue detectors (or something like this), it would have a certain probability to be detected by each. You really could do such an experiment one photon at a time ...
Comment: ... and tally up the number of absorptions by each colour detector (cone, if you like, but hopefully you can see that the idea is much more general), and you would conclude that each photon on its own had a spectral spread. Such perfectly coherent white light, i.e. comprising photons all in the same *pure* quantum state, is indeed possible. It would be pretty contrived and weird, though, and [freude's answer](http://physics.stackexchange.com/a/120073/26076) is the description of "everyday" white light.
Answer: The answer to what electromagnetic frequency "white" is rather both a simple and a complex answer all wrapped into one explanation; here goes...
We all know that the color "white", if you want to call it that, is a combination of all of the visible light frequencies.  Therefore logic dictates that the frequency of "white" must then be "all" frequencies.
Despite this though, this then brings up the age old allegory of which came first the chicken or the egg.  That is, it begs the question of which came first, the color "white", or it components of the red, green, and blue visible spectrums?  It would seem to me that the answer to this would be that "white" came first as a byproduct/reaction of photonic assimilation into the void we call darkness.  (Provided of course that said photon had matter/mass to interact with.)  My thoughts are that "white" came first.
However this is not the end of the frequency question, as once the color "white" is obtained there is actually no true blue, red, and green individual frequencies, as the individual spikes of those frequencies would then all have to be simultaneously peaking at the same instant in time; lest the "white" light would be an impure off-white.  That is, at that instant where pure "white light" is visible there is actually no waveform pattern, as all of individual peaks of blue, red, and green are in linear synchronicity.
Those are my scientific thoughts.
As for my philosophical standpoint I am pondering all that we have heard throughout ours life's about us being creatures of light; that the Almighty is the Alpha and the Omega, the Beginning and the End;  that I Am is in and around everything all of the time; and that we are all created in His image?
Could this be why the persons in the bible, and since that time, have all described the presence of GOD as emanating pure white light that was so intense that they would have to shield their eyes from it?  Could it be that in our current dimension of matter/mass, GOD would appear, consistent with principles of physics, as a combination of all of the electromagnetic frequencies both visible and invisible, all at one time, and in the same astral plane?
I believe that there is something to this that requires further meditation and prayer.
God Bless All.
Jim
Comment: As it's currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Answer: The white light is the combinations of seven 7 colors each having a different frequency  What is the added frequency and the added amount of light in all of the colors it is not only adding but it is also taking it's What is the added frequency and the added amount of light in all of the colors it is not only adding but it is also taking it's frequency so the frequency of the mixture of all the colors is the frequency of white lightfrequency

The frequency of the white light


What word means "eating place"?

Question: The word "dormitory" means "sleeping place". Is there any similar word for "eating place"?
Comment: Since you didn't give a context, I'd echo @Robusto's comment that *dormitory* implies a school setting where the students live away from home, like a university.
Answer: There's also refectory:

A refectory (also frater, frater house, fratery) is a dining room, especially in monasteries, boarding schools and academic institutions. One of the places it is most often used today is in graduate seminaries. It is derived from the Latin reficere: to remake or restore, via Late Latin refectorium, which means a place one goes to be restored. [Wikipedia]

the root of which it shares with restaurant:

Modern restaurants ... emerged only in 18th-century Europe, although similar establishments had also developed in China. A restaurant owner is called a restaurateur; both words derive from the French verb restaurer, meaning "to restore". [Wikipedia]

Oh, and of course beanery, hash house, greasy spoon, & automat.
Comment: +1 for *refectory*. Exactly what I thought of on reading the question.
Comment: "*beanery, hash house, greasy spoon, & automat" - uh, one of these things is not like the others, one of these things just doesn't belong?
Answer: Maybe you're looking for the word "eatery".

One of the best eateries in town.

Also the phrase "eating place" is very common.
There are some other words that I don't think you're looking for them. But you can also check them out.
Other words:
cafe, self-service, diner, bistro, cafeteria, canteen, brasserie
Comment: FWIW as an American, I have never heard someone use the phrase "eating place" in actual conversation.
Comment: In my experience, "restaurant" is the most common word to refer to a place where you buy food and eat it.  "Eatery" is equivalent but less common. "Cafeteria" is more common when referring to a large room in an institution where individuals pick up food from servers behind a counter and take it to their table on a tray.  Some restaurants have a similar serving model but generally a smaller, non-rotating selection. "Canteen" is equivalent to "cafeteria", but usually in a military context, and usually also includes a general store. The other terms you list are all particular kinds of restaurant.
Answer: There are lots of words for "eating place": dining room, cafeteria, restaurant, mess hall (military), galley (Navy), and so on.
Be aware that "dormitory" has a specific meaning, and is usually associated with schools, especially colleges. There are other words for sleeping place, including bedroom. If you're wondering if there are any words for eating place that are derived from the Latin meaning "eat" (as dormitory is from the Latin word for "sleep"), I'm not aware of any.
Answer: Some common "eating place" words are:

bar, cafeteria, café, canteen, chophouse, coffee shop, diner, dining room, dive, doughtnut shop, drive-in, eatery, eating house, eating place, fast-food place, greasy spoon, grill, hamburger stand, hashery, hideaway, hotdog stand, inn, joint*, luncheonette, lunchroom, night club, outlet*, pizzeria, saloon, soda fountain, watering hole src
Answer: A restaurant, a diner, an eatery, and a café are all places where people go to eat meals.
Answer: There is no single word for eating place, there are many.

Restaurant
Diner
Cafeteria
Eatery

You have to make a choice.

What word means "eating place"?


# of iterations in Restricted Boltzmann Machine (RBM)

Question: I have a training set, I provide it (consider a data from training set) to the visible layer. Then the normal process is followed, i.e. Positive Phase-> Negative Phase-> Reconstruction of weights, bias units take place. Does it end here or should I have to iterate with the present visible unit value again (the process follows for few fixed iterations) ? Because it is not properly stated anywhere whether with each data of training set, it has to iterated again and again or with each data of training set.
Answer: When you are unsure about how something (e.g. RBMs) should really be implemented, it is often useful to look at the code of others. G. Hinton himself has published a MATLAB-script (here) which demonstrates the training of an RBM. There, you can see that for each mini-batch, he does the positive phase, then the negative phase, and finally updates the weights - and that's it. So he doesn't iterate between the visible and hidden states.
However, this is not the full truth: for the weight updates we need to know the probability $p(v,h)$. This is very complicated to calculate, as it would contain a sum over all possible states of the RBM. There is a "mathematical trick" called Gibbs sampling: it allows us to iterate back and forth between visible and hidden units to calculate this probability $p(v,h)$.
But: for the result to be correct, we have to iterate forever, which is not really practical. So what Hinton proposed is to iterate for only 1 step instead (this is $CD_1$), so he only goes back-and-forth once.
But, you can also iterate any number of times $k$, which is denoted by $CD_k$.
While for Hinton's $CD_1$, you would do
visible --> hidden --> visible

For a $CD_3$, you would iterate from visible to hidden and back, three times:
visible --> hidden --> visible --> hidden --> visible --> hidden --> visible

And just to be clear: you run this iteration for every data point in the training set. Actually, you usually make so-called mini-batches of maybe 10 data points, which you run at the same time. Then you calculate the average weight update from this batch. But then, you do this iteration again, and again, and again, until you have finished your training.
Comment: "calculate the average weight update from this batch"? Calculate the average of each mini-batch or average among the mini-batches?
Comment: You do the iteration for one mini-batch, calculate the average update for the e.g. 10 examples from *this* mini-batch, update the weights, and repeat for the next mini-batch.


Is it rude to say "Thanks for asking"?

Question: My manager recently asked me "How are you doing? Everything OK?". I felt happy that he asked me that question, and felt that he was really concerned about me. I was doing well. So I told him that and  followed it up with "Thanks for asking." Does the statement "Thanks for asking" sound rude (kind of like I don't need to tell you)? Is there a better way to express the expression or can you use your feelings to prove how you feel?
Comment: It's only rude on SE.
Answer: I find this to be a fairly common exchange in customer service (CS) situations (cashiers, waiters, telemarketers, and the like) these days:

CS: Hello, how are you doing today?
Me: Good, thanks, and you?
CS: I'm doing great, thank you for asking!

Apparently, the phrase "thank you for asking" is considered the height of customer service etiquette now.
So not only is saying, "thank you for asking" not rude, it's a form of politeness that's scripted often into customer service interactions.
Comment: As much as subconsciously I probably know it's scripted, I like to think they are doing it at their own will.
Answer: I'd rather place it among ironical phrases, with rudeness intended or not intended:

— Lend me a grand, dude?
— No such money on me, pal, but thanks for asking.

— I seem to have scratched your car a bit while trying to park… Are you okay?
— Well, not exactly, but thanks for asking.

If the person you're talking to doesn't expect any irony, I'd suggest that you choose some other similar phrase with no potential negative connotations.
As to the better way of expressing your gratitude, I think sincere 'I'm glad that you've asked me' will serve the best. Note that the brevity is your enemy here: even 'Thank you for asking' will be a fitter choice than 'Thanks for asking'.
Answer: I can't imagine a rude phrase containing thank you but that is not so important. In oral conversations most of the politeness lays in the contexts.
If you wanted to answer more formally you should have used something like Thank you for being concerned, It is really very nice of you to ask me.
If it was more informal you can use some slang- Thanks I am mighty fine boss, I am feeling OK like fish in the ocean, I am pleased as a punch today.
It is OK to use Thank you for asking, it is informal. The expressions is not carrying any negative meaning BUT in my humble opinion it is very plain boring answer. Well trying to be social you can ask back:  How about you boss ? and carry on a further conversation.
Comment: I can imagine many rude setences with _thank you_. For example, _thank you for being as big a fool as you look_. Or a simple, ironic, _thanks for your help_ to someone who has not helped etc.
Comment: I would not say "pleased as a punch", but would omit the "a" in there.
Answer: As others have said, when spoken sincerely it's a perfectly fine thing to say. But if you're worried that you will be mistaken for insincere, then there are other phrases like "thanks for your interest" or "thank you for taking the time to ask" that would seem less flip.

Is it rude to say "Thanks for asking"?


How to decrease drop-off rates in mobile surveys

Question: I am redesigning a survey flow. My product team noticed higher drop-off rates with multiple choice questions – the answers often require the user to scroll, and they can't see all of the options at once. There is no way to avoid it (as far as I know). How might we design long multiple-choice questions to be more user-friendly on mobile, so that we can improve their response rates?
Comment: What makes you think abandonment is related to scrolling? Granted, it could be a factor if you're overwhleming users (simple Hick's Law). But it could be the choices are redundant, or too complex, or scrolling behavior makes the continue button hard to find, or there's not enough motivation to complete the task
Answer: There is no great way to solve this issue because, as you mentioned, would have a long list of multiple answers. A possible solution if applicable would be List the 2 or 3 most popular answers and another one entitled "Other". When tapping "other", you would extend the list with the remaining options.
Also take into consideration to not list all questions at once but to present them wisely, to avoid choice paralysis as much possible.
Answer: I don't know best practices
But you can inspire in famous applications survey, like Google, Survey Monkey, and trying to understand why users are give up in this question, what are their needs.


Get tab delimited text from a specific column in excel

Question: I have an MS Excel 2013 spreadsheet in which I have the list of some people attending a conference, their address, phone number etc in different tabs. Now, I've been asked to create a tab delimited list of the attendees for a brochure. Is there a way which can do it without forcing me to retype/copy-paste every single line of the data the data? I only need the name column. I wish to prepare the brochure on MS Publisher 2013. Any help will be appreciated.
Comment: `Public Function get_list(rng As Range) As String: Dim str As String, i As Long: i = 1: While Len(rng(i).Value): str = str & ", " & rng(i).Value: i = i + 1: Wend: get_list = Mid(str, 2): End Function` :D
Comment: This is vba... if you go to the vba module by clicking alt+f11 and then insert a module, you can simply copy/paste the code there. Then in your worksheet insert `=get_list(A:A)` (or whatever range your names are in) and it will output a `,` seperated list of all cell values in the given range (will stop at the first empty cell)... sorry, but I was in a hurry and just by phone, this way no big answer with an explanation :P
Comment: Still, you would need to change the `,` to a `vbTab`. However, you can't set tabs in a cell, this way it would not work as desired :P
Comment: @DirkReichel Can you please tell me what language this is and how to implement it in the spreadsheet?
Comment: @DirkReichel Thanks. I look forward to learning VBA.
Answer:
Get tab delimited text from a specific column in excel
I've asked to create a tab delimited list of the attendees for a
  brochure. Is there a way which can do it without forcing me to
  retype/copy-paste every single line of the data the data? I only need
  the name column.

Here are the steps to do this manually and quickly with Notepad++ in case you're looking for a manual way to complete this easily without code otherwise; plus you have your question tagged at text as well.

Open your Excel spreadsheet with the column you wish to get the data
values from such as the name column.
Click that column to highlight all values and then press
Ctrl+C (or right click and select
Copy).
Open Notepad++ and a new new blank document and then and then press
Ctrl+V (or right click and select
Paste) to paste the values of the column you just copied.
From within Notepad++ with the data values pasted press
Ctrl+A to select everything you pasted, go up and select Edit select Line Operations, and then select Remove Empty Lines (Containing Blank characters)
From within Notepad++ with the data values still all highlighted go up and select Edit select Blank Operations and then select Trim Leading and Trailing Space
From within Notepad++ with the data values still all highlighted press Ctrl+H go to the Replace tab and put in the values and ensure the options are selected just as shown below. Press the Replace All option and that should tab delim all your data values.
From there you can save the newly formatted values as a new text document or copy and paste in that formatt (tab delimited) to your other applications, etc. as-needed if applicable.

Please note I did test this out and confirmed it worked as expected and then turned right back around and imported it into Excel as tab delimited and everything appears to be tab delimited and imports correctly.

Screen Shot

Source: Notepad++ Regular Expressions

\n

The LF control character 0x0A (line feed). This is the regular end
  of line under Unix systems.

\r

The CR control character 0x0D (carriage return). This is part of
  the DOS/Windows end of line sequence CR-LF, and was the EOL character
  on Mac 9 and earlier. OSX and later versions use \n.

\t

The TAB control character 0x09 (tab, or hard tab, horizontal tab).

Additional Note
There is also the Ctrl+A and Ctrl+J feature of Notepad++ but it'll not add the tab to delimit but rather spaces. I'm not sure if your "name" column is first and last name both or just one name only which you could potentially do "space" delimited if you needed to and that works in your case.
Comment: @SayantanSantra I'm glad that helped resolve your issue for your immediate need. Thanks for the question! The code in the comment above by someone else appears to be VB or VBA perhaps. It's not formatted properly because it's in a comment but VB from what I can tell.
Comment: Yeah. It contains both first and last names. And your process worked. Although for my purpose, I found that adding multiple spaces was better than tabs as I need uniform spacing. I'm helping an NGO and it was a last minute work. Thanks for your help. Also, I notice some code in the comments. Can you please tell me what language is that and how to use it?
Comment: Yeah. Thanks. I know c++, but not VB or VBA. I look forward to learning it.
Comment: You also "could" transpose it to one row and then save as tab-delimetered `csv`
Answer:
I assume that you have some knowledge with programming. This way the given names should explain everything. (So i will not explain how the code works.)

To show a proper way to do it with VBA (and make it available to other applications) You could use this script:

First open your VBA window via Alt+F11. Then "Insert" and "Module". You can simply copy/paste the code there

Option Explicit
Sub Put_All_Names_to_Clipboard()
  Dim Name_In_Cell As Variant, Name_List As String
  For Each Name_In_Cell In Selection.Value
    If Len(Name_In_Cell) = 0 Then
      Exit For
    ElseIf Len(Name_List) Then
      Name_List = Name_List & vbTab & Name_In_Cell
    Else
      Name_List = Name_In_Cell
    End If
  Next
  Dim Object_For_Clipboard As Object
  Set Object_For_Clipboard = CreateObject("new:{1C3B4210-F441-11CE-B9EA-00AA006B1A69}")
  Object_For_Clipboard.SetText Name_List
  Object_For_Clipboard.PutInClipboard
  Set Object_For_Clipboard = Nothing
End Sub

It will now put a tab-separated list (text string) of all call values which are selected (it stops at the first empty cell, this way feel free to select a whole column). After the macro is executed, you can simply "paste" the string wherever you want it. However, I suggest to paste it to the right place directly in your publisher-file, which saves 1 step and also keeps your clipboard clean for other tasks.
You can Start the macro directly by having the text cursor somewhere inside the sub and hit F5. You also can assign the macro to a button or add it to the toolbar
As a last hint: You also can crate a macro directly in MS-Publisher and just "get" this string from the excel-file. But that is something you can do later on if you feel better with VBA. :)
Comment: @SayantanSantra I'm not here to get "points" or anything like that. My mission is to help other ppl to get better. And IF you are able to improve your skills than I got all I was looking for :)
Comment: That I'll try to make sure.
Comment: Yeah. I do have some experience. I am an amateur c++ programmer. Your answer explains quite well. But, as the other answer was more user friendly and usable for everyone. That helped me actually get the job done at the hour of need. So, I accepted that instead. Anyway, thank you for this great answer. I shall try to get familiar with VBA in the near future.


Souls That Don't Prove That A God Exists?

Question: Assuming that souls exist within the realm of physics, how could they or some similar continuation of consciousness continue to exist after death, especially without the afterlife being awful, in a way that doesn't prove that a divine being exists?
Comment: Assuming rats can fly using their ears as wings, how do you explain that horses still can't breathe underwater? Those 2 are not connected unless you connect them
Comment: Have you ever hear about Budhism? We have all that souls thing, but no gods.
Comment: Souls "prove" God by virtue of being an extension of his power and beyond the physical reality as we comprehend it. If souls exist within the realm of physics they are simply a natural phenomenon like any other and do not have a special connection to God beyond that of anything else. The "prove" is in quotes because actually proving that souls are connected to God is likely to be impossible. After all if they are of divine power beyond the reach of our science we cannot use them to prove anything. So it is a matter of faith not proof. If you believe in divine souls you'll believe in divine.
Comment: It really helps if you define what a "soul" is. What extra stuff occurs in a universe with soul compared to the real world.
Comment: I wrote my answer, arguing that no proof could exist.  If you are looking for a different answer, a hard-lined definition for "soul" and "divine" will likely be needed.  You'll need to restrict their definitions in such a way as to sidestep the last few thousand years of philosophy.
Answer: Occam's razor is often used to call for the argument "god is not necessary to explain life and universe"
The same Occam's razor you apply above, you can apply to these souls.
Yes, these souls exist. But existing they are just an extension of the universe. if the universe at all doesn't call for the existence of a god, why would these souls make an exception?
Comment: @TheLiteraryLord, how does life work? it's your world where souls are possible, it's not up to me to explain how it works.
Comment: So, how would souls work then, any thoughts?
Comment: @The Literary Lord as Dutch says, they can be anything. What I often use is a dimension or similar that is juuust in the background of our universe. Think of an entire universe of Dark Matter(s) that barely has any reactions with our universe but has an "imprint" of our universe, most importantly of peoples consciousness in the form of a soul-like entity. Through the limited interactions that you can determine yourself you can dictate what can happen. For example "magic" based on using the "real" world to change the imprint and cause the Dark Matter to interact with the real world for a moment
Answer: So this is a quick summary of Buddhism:
There are no gods.
Buddhists seek to reach a state of enlightment and to to that we follow the teachings of several wise people that have come before us. Life is both endless and subject to impermanence, suffering and uncertainty.
So there you have it, souls, but no gods.
Comment: No God in the Abhramic sense I believe but maybe gods (Devas, Asura etc) in other sense.
Answer: This is more of a philosophy question.  As it is, it is one of the largest unanswerable philosophy questions in existence: how do you prove or disprove the existence of a deity or other metaphysical entity.  So the answer to your question is simply "you can't."  Philosophers have spent thousands of years pondering this question, and the answer is always the same: either "you can't," or that philosopher is selling something.
Ironically, having a soul prove a deity exists is easier than proving one does not exist.  While both are still in the "you can't" range, all one has to do is provide one example of a deity existing and it refutes the claim "deities do not exist."  To prove that a deity does not exist requires proving a negative.  One must prove that there is no possible way for a deity to exist.
To demonstrate the difficulty of this, consider the case of the absent creator, which creates the physical world, then goes on vacation and lets it run until the end of days.  This creator then comes back and does something.  There is no physical way to prove this is not the case.  We may use abduction to come to the conclusion that "there are no deities" is true because it is the "best" hypothesis, but that's a far cry from what you ask.
Indeed, the closest you could get would be if the "soul" provably came from some primordial soul-mass as in Secespitus's answer, and returned to it.  Interestingly enough, that is a paraphrasing of the fundamental cosmology of Hinduism, that we are all the Godhead, just divided because the Godhead wanted to be divided, and that one day we will all reunite.  It is also at the heart of the greeting, "namaste," which we most often hear from yoga practitioners.  The meaning of that is often traced back to the idea of bowing to the "divine spark" in you, and in us all.  It is also the structure often found in the druidic religions regarding the divine Earth Mother (e.g Gaia), to which we all return.
So the related question is "how do you define 'divine?'"
Answer: There is simply a big pool of soulmass and whenever something is born there is an empty room, which the soulmass tries to fill. It's like a big pool of water and every living thing is like a very, very small reservoir that can be filled with the soul.
This also means that it's not really your soul versus my soul - we are all the same. The same soulmass, just that our bodies are different reservoirs for small amounts of the overall soulmass.
There is no heaven or hell. Just the body being destroyed and the little bit of soulmass going back to the big part. This also means that nobody cares for your soul after death or distributes it to a different body later on. It just becomes one with all the other souls that are currently not distributed.
Comment: What happens to memories in this scenario?
Comment: That wasn't part of the question, but I'd say that they are not part of the soul. They are simply in the physical brain and can for example be destroyed by illness. The soul doesn't have anything to do with memories and therefore memories wouldn't flow back into the soulmass. But of course you could make them part of the soul in your story, meaning that they are getting into the big pool of soulmass. It's just so big that at most one in every thousand people has some random "past life memories" like we sometimes here in real life.
Answer: Does the formation of particles in empty space imply a deity exists? No. Does the Big Bang itself imply a deity exists? No. The only physics that would imply a deity exists is measurable activity requiring a sentient actor to explain it. If it can all be explained as a natural process, whatever you pick as your physics for souls will likewise not imply a deity exists.


shortening a globe light string

Question: Shortening a globe light string.
I have a 100 foot G40, E12 base, C7 socket globe light string.
I want to shorten it by 6 feet. I have very little electrical experience.
How can I easily do this?
Comment: I'm voting to close this question as off-topic because it has nothing to do with electronics engineering. Maybe a better fit for DIY?
Comment: We're just supposed to know that a "globle light string" and a "100 foot G40" are?  No definitions, no references, *screw this*.
Comment: Is this line voltage (110/120V plug-in style) or low voltage (12/24VDC hard-wired)? Also, what wattage are the lamps and what is the spacing between each lamp? Likely you can just cut the line at the desired length and cap it, but I'd be interested to know exactly what you have beforehand.
Answer: Assuming yours is something like this then the bulbs are in parallel, so all you have to do is cut it and isolate/cap the wire ends; do not connect/short these wire ends together.
Oh, and make sure it's de-energized/unplugged when you cut it.
Comment: Agreed, and I think that "C7" is the most important part.  C7 and C9 lights are 120v, so you can cut the parallel string anywhere.

shortening a globe light string


What is the expected number of d20 rolls needed for at least one 1 and at least one 20 to come up?

Question: Let's say you're playing D&D. You know that for any fair n-sided die, it will take an average of n times before you roll a given face on that die (because it's a geometric distribution). So if you wanted to roll a natural 20, across all the sessions you play it will take an average of 20 rolls of a 20-sided die (a d20) per session before you see a natural 20 for the first time. Each individual session may take more or less rolls to get a natural 20 (let's assume you're rolling a LOT per session, like at least 100 times, and your campaign has infinite sessions), but on average it will take you 20 rolls for the number 20 to show up for the first time in a given session.
Now let's say you want to predict, on average, when your first natural 20 AND your first natural 1 will show up. In other words, what is the expected number of rolls of a d20 needed for at least one 1 AND at least one 20 to come up?
They don't need to appear consecutively; they can appear in any order. You're also only rolling one d20, one roll at a time. Any face can come up any number of times, but you only stop rolling once you've seen 1 AND 20 at least once each.
Answer: Consider the event that a $1$ or a $20$ shows up.  It has probability ${1\over 10}$, so the expected number of rolls until the first of the two numbers comes up is $10$.  Then the expected number of rolls until the other numbers shows up is $20$, as you said.  In all, the expected number of rolls is $30.$


What is Unknown Nullability in C# 8?

Question: In C# 8.0 we can have nullable reference types. The docs state that there are 4 types of nullability. The first 3 are quite clear but I fail to understand the point of "unknown". The docs say it is used with generics but when I try to call a method on an unconstrained variable of T type in generics it just warns as if the type is nullable. I fail to see the difference between unknown and nullable. Why does unknown exist? How does it manifest itself?
Answer: Take the following generic method:
public static T Get<T>(T value)
{
    return value;
}

If we call it like Get<string>(s), the return is non-nullable, and if we do Get<string?>(s), it's nullable.
However if you are calling it with a generic argument like Get<T>(x) and T isn't resolved, for example it is a generic argument to your generic class like below...
class MyClass<T>
{
    void Method(T x)
    {
        var result = Get<T>(x);
        // is result nullable or non-nullable? It depends on T
    }
}

Here the compiler does not know if eventually it will be called with a nullable or non-nullable type.
There is a new type constraint we can use to signal that T cannot be null:
public static T Get<T>(T value) where T: notnull
{
    return value;
}

However, where T is unconstrained and still open, the nullability is unknown.
If these unknowns were treated as nullable then you could write the following code:
class MyClass<T>
{
    void Method(T x)
    {
        var result = Get<T>(x);
        // reassign result to null, cause we we could if unknown was treated as nullable
        result = null;
    }
}

In the case where T was not nullable, we should have got a warning. So with unknown nullability types, we want warnings when dereferencing, but also warnings for assigning potentially null.
Comment: In terms of warnings they behave the same, but they are semantically different. You could say the difference is academic, and if that was your point then I agree.
Comment: I would still like to know why the difference was introduced. It seems strange to introduce such a distinction in the language for academic purposes.
Comment: Ah that's more like it
Comment: When I do  var result = Test.Get(x); result.ToString(); the compiler complains about dereferencing a possibly null value. I don't see how unknown is different from simply nullable in this case.
Comment: My bad, just re-read the spec, update the answer, the last part explains it.

What is Unknown Nullability in C# 8?


What are some kavachas you use?

Question: There are so many Kavachas available. I am interested in finding out which ones you use?
If you use multiple ones depending on the scenario, I would love to know the details too.
Answer: Rahu Kavacham. Since the current Mahadasha that is running is Rahu for me. I also use the Kavacha for the relevant Grahas when the relevant Praana Dasha comes in, on average every 2-3 days.
Since the Kavachas are slightly like Mantras and utilize (pseudo) nyaasas, it's best to not do many and keep the connection to as few as possible (preferably one). So, that's all that I use, 9 in total. Along with Aaditya Kavacha from Skanda Purana which I use daily.

There are so many Kavachas available.

If you want to find which one to use, yourself, then look at the Phala Shruti that is most suited to your wants and just pick one with a Deva you feel more connected towards. That's pretty much all there is.
Comment: thank you , thats great suggestion.

What are some kavachas you use?


Google Form API?

Question: I would like to (programmatically) convert a text file with questions to a Google form. I want to specify the questions and the questiontypes and their options. Example: the questiontype scale should go from 1 to 7 and should have the label 'not important' for 1 and 'very important' for 7.
I was looking into the Google Spreadsheet API but did not see a solution.
(The Google form API at http://code.lancepollard.com/introducing-the-google-form-api is not an answer to this question)
Answer: Google released API for this: https://developers.google.com/apps-script/reference/forms/

This service allows scripts to create, access, and modify Google Forms.
Comment: Note that this is not a REST API, but rather a feature of Apps Script.
Comment: Is it only available for G Suite customers??
Comment: Is there an official CDN from Google to include the script(s)?
Comment: @SlickSlime - Possibly (even likely), because it is included in G-Suite services. I never *used* this API, I just found it when I was doing a research for our in-house project similar to OP's question. That project was never started, sadly, so I do not have first-hand experience (but I do have constitutionally-protected right to have opinion, even if I never used it :-)  We use G-Suite so for us such requirement would not be a problem.
Answer: Until Google satisfies this feature request (star the feature on Google's site if you want to vote for it), you could try a non-API approach.
iMacros allows you to record, modify and play back macros that control your web browser. My experiments with Google Drive showed that the basic version (without DirectScreen technology) doesn't record macros properly. I tried it with both the plugin for IE (basic and advanced click mode) and Chrome (the latter has limited iMacro support). FYI, I was able to get iMacros IE plug-in to create questions on mentimeter.com, but the macro recorder gets some input fields wrong (which requires hacking of the macro, double-checking the ATTR= of the TAG commands with the 'Inspect element' feature of Chrome, for example).
Assuming that you can get the TAG commands to produce clicks in the right places in Google Drive, the approach is that you basically write (ideally record) a macro, going through the steps you need to create the form as you would using a browser. Then the macro can be edited (you can use variables in iMacros, get the question/questiontype data from a CSV or user-input dialogs, etc.). Looping in iMacros is crude, however. There's no EOF for a CSV (you basically have to know how many lines are in the file and hard-code the loop in your macro).
There's a way to integrate iMacro calls with VB, etc., but I'm not sure if it's possible with the free versions. There's another angle where you generate code (Javascript) from a macro, and then modify it from there.
Of course, all of these things are more fragile than an API approach long-term. Google could change its presentation layer and it will break your macros.
Comment: A forms API is now supported. (docs are [here](https://developers.google.com/apps-script/reference/forms/?hl=es-ES).)
Comment: Is it possible to run the Form API in Java or C#?
Comment: @JeffreyLin doesn't look like it yet... https://developers.google.com/api-client-library/java/apis/
Comment: Thank you for your reply. I had checked the page. However, I do not find "Google Forms API" or "Google Apps Script API" in the listings. Therefore, I would like to know whether it is possible to run Forms API with these libraries or not.
Comment: @Greenhand Create your script on their google engine, then kick it off using their REST API. So you can't write it in Java or C#, but you could cause execution of a script in those languages.
Answer: Seems like Apps Script now has a REST API and SDK's for it. Through Apps Script you can generate Google Forms. This API was really hard to find by trying to google for it and I haven't yet tested it myself, but I am going to build something with it today (hopefully). So far everything looks good.
EDIT: Seems like the REST API I am using works very well for fully automated usage.
Answer: In March(2022) google released REST API for google form. API allows basic crud operation & also added support for registering watches on the form to notify whenever either form is updated or a new response is received.
Answer: As of now (March 2016),  Google Forms APIs allow us to create forms and store them in Google Drive. However, Forms APIs do not allow one programmatically modify the form (such as modify content, add or delete questions, pre-filled data, etc). In other words, the form is static. In order to serve custom, external APIs are needed.
Comment: How about dynamically updating form response data based on previously entered data by the same user? This is similar to allow user to modify their response after form submission. The difference is to pre-create response in the form based on user email address.
Comment: The Google Form API doesn't include methods to make the form dynamic but the question isn't about that and the answer isn't not clear, I think.

Google Form API?


jQuery Sortable Cannot Click After Sort Issue

Question: I have a table that is being sorted by the TR tags, everything works fine except that I have to click twice on any item in the list after something has been moved for anything to respond, on links etc. Do I have to call some function after the list has been sorted to re-activate it so that I don't have to click twice on items?
Answer: Can't truly understand the issue without code samples but if you believe that refreshing could solve it you probably need <code>.sortable('refresh');</code>


What is the generally accepted resolution for mobile design?

Question: So, I am a week and a half into a new project, and I've been designing for a resolution of 320px * 480px. I am new to the game and I've just found out that that resolution is too small considering the high density displays of newer smartphones, and that my graphics will look blurry on new devices.
My ignorance is really costing me and I'd like to find out if there is an equivalent of the stock resolution mentioned above (which I assume was used before the high density displays were introduced).
If you have any suggestions on how I can salvage my existing graphics short of redoing the .PSD's that will also be appreciated.
Answer: Instead of designing your UI for a single resolution, you should design it to be resolution-independent. Take a look at how this is handled in Android:
http://developer.android.com/guide/practices/screens_support.html
The resolution you are using (320x480) is a typical MDPI resolution, so you could basically continue using it, as long as you deliver your graphical assets for the app in other DPI sizes as well:

LDPI (low): x0.75 the size of your current graphic assets
MDPI (medium): the size of the graphical assets you are currently using
HDPI (high): x1.5 the size of current assets
XHDPI (extra high): x2.00 the size of current assets

The operating system then uses whichever graphic is the best fit for the device.
In iOS, all of this is much easier, as you just have to provide two graphic assets, one for old screens (320x480) and one for new retina screens (640x960).
Comment: Your answer is talking about pixel density, not about resolution.
Comment: You're right, I clarified the answer a little. The different sized Android graphical assets do link to screen sizes as your answer illustrates.
Answer: The resolution that you design for depends on the resolution that your target audience will be using.  Sometimes you know this in advance, but if not, you need to try remain flexible within a set of resolutions.
This is one of the reasons that responsive design is so useful. You need to design without a fixed resolution in mind, but design in a way that is flexible and will work for a range of resolutions.  I would typically look at iOS and Android resolutions (with Android being the largest market share), and make sure that any design works well in either of them.
You also need to distinguish between hardware resolution and design / css resolution as for many phones the two are not the same.
Android Resolution Chart:
Answer: What can be confusing is that there's the screen dimension resolution, and then there's the pixel density resolution. They're often related, but not always.
For instance, an iPhone 3 is 320px * 480px.
And iPhone 4, with Retina display is 640 x 960.
However, both devices treat the screen as being 320 px wide. It's just that the Retina display will have double the pixel density available to it.
As an example, if you created an icon 100x100 and displayed it on both devices side-by-side, they'd look physically the same size. To take advantage of the retina display, though, you'd create a second icon 200x200 and give that to the retina device. It will still be the same physical size, but now has 4x the pixels so will be sharper/clearer.
And easy way to design for iOS is to take your PhotoShop file, set it up at the retina display dimensions, and then design viewing it at 50%.
Alas, iOS makes it fairly easy to do all this as there's a fairly direct relation between the two types of screens. This isn't always true on other devices--especially BlackBerries, where a higher pixel density screen usually equates to having more content on screen, but all the content rendering much smaller.
Answer: The reason for blurriness is that when the image is increased in size there, it is not increased in perfect numbers, ..
If you set the main resolution to 100x100, it will look fine on 200x200 and 300x300 ..etc, but it will not look fine on 150x150 or 160x160.
If the image is increased in size or decreased in size by 1x,2x,3x,4x, or 0.5x,0.25x,0.125x it should be fine, not perfect though.
You should consider making it resolution independent, your application should detect the resolution and handle display accordingly.
Comment: +1 for mentioning blurriness resulting from imperfect scaling. This can have a huge impact, especially if your assets have already been scaled from a source image. I always recommend starting with the full resolution (or vector) source image and only scaling raster images (non-vector) down by negative powers of 2 (0.5x, 0.25x, 0.125x, etc.).
Answer: Most of the current mobiles and tablets are of very high resolution.
1080x1920 could be an average option for now a days (Sep 2017).
Please check the below link
https://mydevice.io/devices/
Answer: Every graphic element that is not a photo should be designed as a vector to save you the pain of having to recreate your assets if something needs to be scaled up.
Meanwhile, high-resolution photo assets can be placed within Photoshop as smart objects also making them resizable to a point.
If you use both of these methods it shouldn't matter what size your Photoshop file is at the design stage.


Finding articulatory profiles

Question: I have two questions. The first is how is it better to call such pictures? Is the term 'articulatory profile' alright? The second: is there a place on the internet or elsewhere which contains many pictures of that kind for various sounds of different languages? I'm aware of, e.g., https://www.seeingspeech.ac.uk/ipa-charts/ but that's not exactly it.
Answer: Usually, pictures like that are referred to as "sagittal sections" (sagittal referring to being split down the plane dividing left from right).
If you want an interactive cartoon of sagittal sections in phonetics, you might want to check out http://smu-facweb.smu.ca/~s0949176/sammy/. Similarly, this youtube channel https://www.youtube.com/channel/UCFuOFZ0wFoHK2deKFldaLGA does a lot of videos phoneme by phoneme on a cartoonish sagittal section.
If you want videos that use an MRI to take sagittal sections of people talking, this youtube playlist has a bunch https://www.youtube.com/watch?v=Z8yysjQeYT4&list=PL7TNe5tKMpG6S57Gn7AszyRhDNOyjlcBv.
Answer: A brief note on terminology. The pictures like the one in question are also called mid-sagittal (or, informally, head) diagrams and can be found in different works on phonetics or speech science. For example, many of them for the Russian language are given in the book called A conspectus of Russian speech sounds by K. Bolla.

Finding articulatory profiles


Do drones fly because of low pressure above them or high pressure below them?

Question: I was working on some drone battery life solutions and was stuck with the question whether drones fly because of low pressure created above them by the rotor or due to high pressure created below them.
Comment: Both. Wings fly due to a sufficient pressure *difference* across their upper and lower surfaces.
Comment: The answer to your question is...  Yes.
Answer: The same principle applies to an aircraft whether it is kept aloft by a fixed wing or a rotary wing, usually known as a rotor. A combination of high pressure below the wing or rotor, and low pressure above, is what keeps the aircraft airborne.
Answer: I noticed the other answers phrase the answer in terms of pressure difference.
However, in the case of an aircraft (flying high above the ground) any pressure difference is a side-effect rather than a cause.
The one case where pressure difference is central is with the kind of hovering that a hovercraft does. The air does continuously escape from under the skirt, but if you replenish that air fast enough a sufficiently high pressure is maintained underneath the hovercraft. That air pressure is truly carrrying the hovercraft.
As a straightforward example of a high flying aircraft with a rotor lets take the case of a helicopter.
When a helicopter is high up, multiple times its own height, then I rather expect that the actual air pressure below it and above it aren't that much different. Sure, air above it is moved down, but surrounding air can easily flow in. Air is moved fast to the space below the helicopter, but again, it can easily move out of the way.
The rotor is creating lift by accelerating air mass downwards.
To imagine what is taking place imagine the following setup: you are the pilot of a small, one person hovercraft, and you throw something fairly heavy away from you, horizontally. You throw the object, and as consequence there is a recoil, so your own velocity changes a little too, in the opposive direction. By accelerating something else you have accelerated yourself too (in the opposite direction).
That is how a rotor creates lift: by accelerating a lot of air mass downwards you generate a tendency to move upward that counteracts gravity.
Again, pressure difference is a factor only when a body of air is sufficienly trapped, such that you can replenish the air that escapes. In the case of a helicopter it is all about accelerating air mass towards the direction that you want to move away from.

The comment by Ján Lalinský indicates to me that some further discussion is warranted.
Some general remarks about the way a rotor has effect:
For a rotor to have an effect the blades (the airfoils) must be accelerating air mass. Now, of course in the overall process of accelerating air mass there will be some degree of compression of air mass.
Let me compare the following case:
A golfbal that is accelerated by being hit with a golfclub. Slow motion footage of a golfbal that is hit very hard (with a heavy club) shows that the golfbal is deformed a lot. Obviously the elastic deformation of the golfbal plays an important role in the transfer of kinetic energy from the club to the ball. Still, we will say that the ball is accelerated due to being hit by the club. The deformation of the ball is an intermediate stage of the overall transfer process. So we don't say: the ball is accelerated due to the elastic deformation of the ball. We say: the ball is accelerated due to being hit by the club.
It seems to me that any compression of air mass in the process of an airfoil accelerating air mass should likewise be seen as an intermediate stage in an overall transfer process.
And here is another way of looking at this issue:
Airfoils are optimized for generating lift. For a given power input you want a maximum of lift generated. Question: what would happen if you design to generate maximum pressure difference, at the expense of all other properties of the airfoil. If you change the shape of an airfoil in such a way that the shape will tend to trap air mass then for sure you will get a lot more pressure difference. But obviously such an air trapping airfoil would have terrible performance because the shape would obstruct the air flow.
Conclusion: If you design to generate maximum pressure difference at the expense of all other properties of the airfoil you lose more than you gain. In fact, you will lose everything. This conclusion corroborates the view that compression of air mass that occurs in the process of generating lift is an intermediate stage in an overall transfer process.
Comment: I think it would clarify things to distinguish pressure right on top and bottom of the airfoils, and pressure of the surrounding air above and below the aircraft. Difference in the latter pressure may not be much, especially if measured far away from the aircraft. However, significant increase in the former across the airfoil is absolutely necessary to generate the lift, because this air pressure difference provides the force that acts against the gravity to keep the aircraft from falling down. Because air is fluid, this pressure difference also generates accelerating air stream.
Comment: Now what is causing the air to be accelerated? Magic? No, it's that pressure difference! Far from being a side effect, it is the actual cause of acceleration and thus lift. Look closely at the rotor blades: What causes them to lift the helicopter?
Answer: Answer: It is both--> it is the pressure difference, top-bottom-difference providing a net upward force.  Pressure over an area is force. More below...
Peter has it correct.  It is ALWAYS a pressure difference pushing up because there is more pushing up on the lower surface than there is pushing down on the upper surface.
Ján also has it correct in that these pressures slowly go back to atmospheric pressure as you move away from the wing. The changes from atmospheric are "local".
However, Cleoins is close, but hasn't quite got it. At a high altitude a helicopter does indeed have more trouble hovering as you reasoned, but there is a maximum hover altitude (actually density).  It is a hover maximum because as you say, the rotor is sitting in the column of air already moving down.  It can't accelerate it any faster and, therefore it can't put any more downward force on it. Go too high and the column is accelerating down as much as the rotor can speed it up (accelerate) it.   The rotor can add only so much velocity and as density decreases, so does the mass and delta V (A) times mass decreases.
Now,
when a heli is in forward flight, you are constantly moving over into new column of stationary air.  Therefore, the rotor can accelerate new air downward.  A fixed wing does this by default, constantly moving into new, still air.
Now for the meat of the lift story.
You must get the desire out of your head to look for some complex story. It is simple and so many people miss the obvious in the search for Bernoulli, Newton's Third, circulation, Kutta, etc.

First, remember Newton's 1st Law is supposed to teach us that a force is required to accelerate a mass (ANY mass).
Second, Air has mass.
Third, it is a pressure difference between two regions that accelerates air.  This 'difference' is called "pressure gradient" because it changes gradually from point A to B. The higher pressure accelerates air toward the lower pressure region. That is WHY, in the commonly cited case, it is moving faster when it gets to the lower pressure region.  A higher pressure (the net difference) accelerated it there.

THEREFORE, TA-DA!
The pressures which provide the upward lift force on the wing, are the VERY SAME PRESSURES that accelerate the air downward behind the wing/rotor.
Under-wing it is a bit more obvious. Looking at a wing with a moderate angle of Attack, it is easy to see that as the wing and air approach each other (Either in a wind tunnel or flight) the pressure must increase.  It is like the wind hitting me, or me running into the wind. This is really easy to feel in water. You really must push against the water to run!
YOU are pushing on the air/water and, therefore, this relative motion is increasing the pressure under...  This pressure on the bottom surface pushes BOTH up on the wing and down on the air below it.  This causes that air to follow a curved path downward.
Here, we see that there is a higher pressure on the outside of the curved flow which is the centripetal force as the say "turning" the air. This accelerates that air into the downwash.
Above wing, The air must follow the curve (I won't go into detail, but in "normal" flight we know it does).  Think of being on a merry-go-round.  Your inertia tries to keep you going straight and you "pull" away from the center.  Above the wing - SAME THING.  This relative motion of the curved AIRFLOW lowers the pressure at the surface. [mote it's not speed causing it, but curved flow] ... No Bernoulli, or anything else.
---- EDIT: Forgot to mention.
The low pressure above (that is caused by the curved flow) does three things:

It is the lesser pressure 'half' of the difference for lift.
It allows the higher pressure ahead of the wing to push, accelerate air toward the trailing edge. This is the acceleration that has the air moving 'faster' in the wind tunnel view.  ***
It allows the atmospheric pressure farther above the wing to push air down from well above the wing adding to the downwash. Downwash air comes from above and below the wing.

*** Data from a wing flying through stationary air shows that the upper air actually reverses direction as it 'crests' the upper camber. It starts being pushed forward (and up) in the bow wave ahead of the wing, then because of the pressure gradient (lower over the wing) it is yanked rearward, totally reversing direction to travel toward the trailing edge. This is shown in a diagram in my blog, linked in this posting.
NOTE ALSO: Acceleration is the "change in velocity" talked about in "Bernoulli's Principle", NOT SPEED!
People like to call pressure a scalar; that is, it has no direction.  However, in a sense, it pushes in all directions.  ANY higher pressure region pushes toward all nearby lower pressure regions. This includes nearby air and surfaces.
This easily explains the bow-wave effect (up-wash) ahead of the wing.  With more pressure under than above, air is pushed in front of the wing so it is "trying" to get up to the top - same way it is around the tips - up and over, so to speak.
--- END EDIT ---
IN ADDITION; PLEASE NOTE that we are dealing with ACCELERATIONS OF AIR.  Acceleration is the same whether we observe this from a moving air, fixed-wing reference frame in a wind tunnel, or in still air, moving-wing frame.  Accelerations are not dependent on speed of observer, whereas speeds are.
THEREFORE, it is the same science in the wind tunnel as flight.  The talk about Faster air above the wing is frame of reference dependent.
PLEASE NOTE that I said "AIR FLOW". This is important because it isn't simply wing shape, but flow shape!  A completely flat wing has the very, very similar kind of curved flow around it.!.!.!.  SAME John Anderson's book shows this.
For my full explanation (with pictures) with all the misconceptions explained, go to my Understanding Lift Blog: https://www.quora.com/profile/Steve-Noskowicz/Understanding-Lift
How do I know this?  I took responsibility for a sophisticated full cockpit flight simulator some years ago and decided to brush-up.  I saw so much misconception on the web, I figured-out just about all of this myself, then talked with two experts actually in the field (not just people repeating others), Boeing's Doug McLean and Embry-Riddle's Charles Eastlake, to verify it and clear some things up. (because many years ago in pilot training I heard the equal transit time story and didn't look into it though it didn't satisfy me)
Best Regards, Steve
P.S.
A Cessna 172 has a wing loading of only 0.1 PSI. That is the difference in lower-upper pressure. With a wing area of 25,000 square inches, this gives PxA = 0.1 x 25,000 = 2,500 pounds loaded aircraft weight.
It turns out that the Decrease above is greater than the Increase below, this is something like 0.04 psi more below the wing and 0.06 psi less above.  So the changes in pressure is barely One-Half Percent at low altitudes. --> 0.06/14 psi = 0.429% change from atmospheric pressure.
Airliners are about 1 psi loading.  So flight is really a very small effect, so to speak.  Why we need large wings!
This difference MUST be the same at any altitude, so at higher altitudes it is a larger percentage change due to the less dense / lower absolute-pressure air and, therefore higher air-speeds are required to get the same lift.
Also please note that the density change (compressability) is negligible and not a factor in normal flight.
Cheers


Appropriate Non parametric statistics

Question: am in doubt as to type of analysis to employ in my research. My topic is the impact of non interest banks to the growth of small-mediumscale enterprises. The questionnaires were administered only to SMEs who have used the non interest product . information obtainned include the total assets and number of employees before and after the use of the non interest product. The sample size is 20 SMEs.
Comment: The nonparametric test analogous to a paired t-test is the paired rank sum test.  The nonparametric analogue to the two-sample t-test is the Mann Whitney test.  For me, the question isn't clear enough to know if either of these or some other test would be appropriate.
Comment: What is really helpful when asking a question is to include a toy data set resembling your data, explain what each variable is, and be specific as to what question you are trying to answer.
Comment: What is the aim of your analysis? What is exactly your problem in here?
Comment: @Tim...  I am investigating whether or not there is a siginficant between the non-interest banks and the growth of small-medium scale enterprises
Answer: A simple t-test would suffice for showing if the SMEs are the same before and after the use of the banks. Nothing non-parametric about this
Comment: @ sal mangiafico. Am just looking for the most appropriate data analysis technique to solving the problem.. Both assets and number of employees are determinants    of growth in a enterprise..logically an increase in assets and number of employees will signify growth while a decrease   will show other wise.  Using non interest product has it own benefit such as access to loans Without interest pay back compared  to the conventional Banking system. I hope you understand better

Appropriate Non parametric statistics


Requires a valid Date or x-amz-date header?

Question: I'm getting the following error when attempting to upload a file to S3:
S3StorageError: <?xml version="1.0" encoding="UTF-8"?>
<Error>AccessDenied<Message>AWS authentication requires a valid Date or x-amz-date header</Message><RequestId>7910FF83F3FE17E2</RequestId><HostId>EjycXTgSwUkx19YNkpAoY2UDDur/0d5SMvGJUicpN6qCZFa2OuqcpibIR3NJ2WKB</HostId></Error>

I'm using Django with Django-Storages and Imagekit
My S3 settings in my settings.py looks as follows:
locale.setlocale(locale.LC_TIME, 'en_US')
DEFAULT_FILE_STORAGE = 'backends.s3.S3Storage'
AWS_ACCESS_KEY_ID = '************************'
AWS_SECRET_ACCESS_KEY = '*****************************'
AWS_STORAGE_BUCKET_NAME = 'static.blabla.com'
AWS_HEADERS = {
       'x-amz-date': datetime.datetime.utcnow().strftime('%a, %d %b %Y %H:%M:%S GMT'),
       'Expires': 'Thu, 15 Apr 2200 20:00:00 GMT',
}
from S3 import CallingFormat
AWS_CALLING_FORMAT = CallingFormat.SUBDOMAIN

Thanks for any help you can give!
Answer: I found that timezone difference seemed to be a factor. I'm an expat from Melbourne who's currently in Malaysia. Changing back to my Melbourne timezone and this error went away (was occuring in all major s3 access tools I was using such as s3fox, s3hub etc.).
Answer: I think it's a bad idea having the 'x-amz-date' header in your settings.py as this file only gets run once each time the server is started.
I guess you were using the development server, which gets restarted every time you change some .py code.
Anyway, django-storages already has code to set the relevant header so you don't need that line at all.
I did additionally have a problem with the header as set by django-storages, see this issue on BitBucket for a fix:
http://code.welldev.org/django-storages/issue/56/aws-authentication-requires-a-valid-date-or-x-amz-date
Answer: Try using formatted UTC zulu time:
datetime.utcnow().strftime('%Y%m%dT%H%M%SZ')

'20220830T153825Z'

ie.
AWS_HEADERS = {
       'X-Amz-Date': datetime.datetime.utcnow().strftime('%Y%m%dT%H%M%SZ'),
       'X-Amz-Expires': 3600,
}


In radiotherapy, why do normal tissiue or organ cells not die of radiation?

Question: In radiotherapy, why don't normal tissiue cells or organ cells in the way of incoming radiation die, but tumours die instead?
Comment: They do. That's why chemotherapy patients lose their hair and don't feel well in general, cancer aside.
Comment: @DKNguyen Chemotherapy is not radiotherapy.
Comment: @DKNguyen - and radiation-only patients as well, as I have personal experience with. There is long-term damage to non-cancerous tissue from radiation treatments as well. Just better than dying from the cancer.
Comment: @noah I guess my terminology is wrong. They are so often accompanied by each other I always assumed radiation was intrinsic to chemotherapy.
Answer: Living cells which are in the process of actively dividing i.e., replicating DNA strands, peeling them apart and sorting them out, rebuilding them into duplicate genes, and so on are particularly susceptible to any sort of challenge which might create transcription errors- most of which would lead to the death of the cell by either jamming the transcription machinery itself or leaving the daughter cells unable to function correctly.
Since cancer cells are almost always in the process of uncontrolled growth, at any point in time most of them in a tumor will be actively dividing. This puts them at much greater risk of being killed by chemicals or radiation than the noncancerous tissue nearby.
Note that since the cells lining your digestive tract and the cells that produce hair growth are also frequently dividing, they will be killed too as a side effect of chemo or radiation. This is why your hair falls out and your digestive system is seriously damaged by chemo agents in particular, since those agents circulate throughout your blood stream and are not "beamed" specifically at the tumor.
Comment: FYI, Radiation and Chemo treatments typically are delivered as a regular sequence of doses called [_fractions_](https://en.wikipedia.org/wiki/Dose_fractionation). Each fraction is supposed to be not-quite-enough to kill healthy cells, and the interval between fractions (one to two weeks) is supposed to allow enough time for the healthy cells to recover. ISTR there are around eight or ten fractions in a typical treatment.
Comment: this is the best we can do right now, except for experimental gene therapy.
Comment: @SolomonSlow, +1 from Niels. I am a cancer survivor cured by surgery, and fortunate that i needed neither chemo nor radiation.
Comment: So basically we just kill the cancer cells with a higher probability than healty cells and "hope" to find the balance to kill the cancer without killing the patient?
Answer: There are two main reasons for this. First, there isn't a single direction the radiation is applied from. Instead, beams from multiple directions are directed at the affected body part. The part where all the beams overlap is the volume recieving the highest radiation dose. Ideally this is where the pathological tissue (e.g. a tumor) would be.
Second, healthy tissue is better at regenerating from radiation damage than cancerous tissue. Therefore, over the course of many radiation sessions, the surrounding tissue can heal (to some degree), while the damage in the tumor accumulates over time (also to some degree).
Answer: Healthy tissue will get damaged by radiation, but it's a matter of degree. The goal of Radiotherapy is to limit radiation dose to healthy tissue as low as practicable while maximising the possible dose to the targeted tumour.
One way of doing this is using a moving beam, or multiple intersecting beams.

If you look at the radiation source here, you can see that the whole device is designed to pivot around the patient. This means that as it moves, the tissues it sweeps the beam through get a lower dose than the point along the axis of rotation. This means that the tumour can be targeted to get a much larger dose of radiation than the surrounding tissues.
Comment: In the most common form of radiation therapy, so-called [_3D conformal therapy_](https://hillman.upmc.com/cancer-care/radiation-oncology/treatment/external-beam/3d-conformal), the machine does not rotate during treatment. Rather, they shoot dose from four or six different stationary _ports_ (viewpoints), and they use shielding material to shape the cross section of the beam at each port to match the outline of the target as seen from that port.
Comment: In a more advanced (i.e., expensive) technique called [_intensity modulated radiation therapy_](https://hillman.upmc.com/cancer-care/radiation-oncology/treatment/external-beam/intensity-modulated-imrt), the machine _does_ rotate while delivering dose, and the intensities of individual "beamlets" are modulated as it rotates. IMRT works kind of like a CT scan in reverse, and like a CT scan, it has to be delivered in "slices." That makes it take longer/cost more than conformal therapy. IMRT usually is reserved for more difficult cases in which sparing nearby healthy tissue is a high priority.
Answer: They do die. That is why radiotherapy can lead to other problems. It kills all cells around the point where the radiation hits. But the human body is good at regenerating.
Comment: Chemotherapy is not radiotherapy.
Comment: @noah, but Chemo and radiation have a lot in common. (See Niels Nielsen's answer.) Both treatments indiscriminately damage the DNA of living cells, and the effectiveness of either treatment is due to the different ability of healthy cells vs. diseased cells to repair that damage.
Comment: @SolomonSlow That doesn't mean they can be used interchangeably, they have completely different mechanisms to attack the patological tissue.
Comment: Thanks for correcting me. I forgot about that.
Comment: I accidentally put that in.
Answer: I suggest you look up "Medical Physics". Cancer is treated locally, by burning "only" the damaged tissue. The role of a Medical physicist is exactly that of studying, case by case, the amount of radiation needed to destroy only the necessary - no more, no less.
Answer: In shooting ranges, why don't people get shot, the shooting targets get shot instead? Because the guns are aimed at targets instead of people. The same is true for radiotherapy, radiation is aimed specifically at tumors.
Actually that was simplification. See, people occasionally do get shot at shooting ranges. Likewise, it is impossible to aim the radiation is such a way that the cancer gets 100% of the dose and healthy tissue gets 0%. But you still could do a lot to minimize exposure to healthy tissue and organs.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Comment: This is a very bad analogy. A tumor inside the body in this case would correspond to a target being surrounded by people on all sides.


Shear Wall Boundary Element

Question: When can I design a boundary element of a shear wall as a column?
Is there a link to a solved example?
Help please.
Answer: We usually design boundary elements of concrete shear walls in multi- story buildings as columns.
The stirrups and ties in the end of the wall allow strengths and ductility past the plastic limit of rebars. they do this task in two ways.
They hold the concrete together even after great lateral forces have caused huge hammering strikes causing large cracks in concrete, thus giving the occupants more time to exit the building before collapse.
They also define a clear path for earthquake vibration sparing the vulnerable parts of the structure.
Answer: It is all about the stress limits of the wall material - compression, shear, and tension, as shown in the sketch below. Another particular concern, for a short wall, is the limit on the lateral displacement (wall rigidity/flexibility), which is a crucial concern in tall buildings.  (Note, for a slender wall, buckling may occur prior to compression failure)
Depends on the wall material (wood, masonry, reinforced concrete), each structural design code has its own requirements/guidelines on the design of the shear wall (with or without the boundary elements) that you shall familiar with. You can google the subject "xxx shear wall design" to bring up quite a lot of examples on the design of walls under the specified material (XXX).

Shear Wall Boundary Element


Is current/resistance a parabola? (For lack of a better word)

Question: So it occurred to me today that is resistance is the load that draws current, but also the thing that limits it, wouldn't a graph of current to resistance increase, but then decrease?
Comment: What you're thinking about isn't current but power. Look up the "maximum power transfer theorem": the load resistance should match the source resistance for maximum power transfer. This is why a switch dissipates no power when it is off or on, but dissipates power if it has a finite resistance. (And it's not a parabola, but does go to zero at the ends.)
Comment: There is a clear and simple formula given by Ohms Law. Do you know it?
Comment: Yeah, it's V = I/R, but if current I'd drawn by resistance, and then limited by it, then isn't there only a certain amount of resistance that can be applied to a circuit before the current drawn and current limited are equal?
Comment: Is [this](https://www.electronics-micros.com/img/electrical/max-power-transfer4.jpg) what you have in mind? That is to do with power transfer with a source that has some resistance, showing power delivered vs load resistance.
Comment: So it's not current that is drawn by resistance, it's power
Comment: Voltage drives Current. Resistors limit the flow. Increase the resistance, you decrease the current with an inverse relationship (V = I x R).
Comment: Ah, I see now. So the reason resistors are included in example circuits is to limit overdrawn on current
Comment: For V=I*R the I*R would be a constant on a graph, a hyperbola.
Answer: here is a graphical inverse relationship when Voltage is constant (10V) and \$R=\frac{V}{I}\$

However sometimes current is constant then means V is proportional to R using same formula above or rearranged V=IR or in the EU,   U=IR
Here is a another way to show same data

Here are 3 circuits with resistance and reactance with R,L,C & f chose to give the same impedance , current and power but at different phases.
The series 100R current and power for each circuit is shown in same order as schematic. Which one dissipates the most real most total?
http://tinyurl.com/jm6nuel

The scope only shows power in the 1st resistor.
Answer: Nothing actually "draws" current (or power).  You might say that current is pushed by voltage, and that current is limited by resistance.
Try playing with the Power equation \$P=VI\$ in terms of Ohm's law \$V=IR\$.  You may be looking for the following intuitive effect:
If you replace \$I\$, for example, with the equivalent \$\frac{V}{R}\$, you get \$P=\frac{V^2}{R}\$:

As you decrease the resistance in a real system, however, eventually the power source won't be able provide enough current.  Then it will fail / shut down / burn up :)
Answer: To expand on my comment, you're probably thinking about the behavior of power. For a fixed current, more resistance means more power. But more resistance also means less current. How does this play out? As you suspected, the power goes up with resistance and then down.
To be specific, the Maximum power transfer theorem says that maximum power is transferred when the load resistance matches the source resistance.
Suppose you have the situation below, where \$R_1\$ is the load resistor you are varying, and \$R_2\$ is the fixed source resistance. You get the maximum power for \$R_1\$ when \$R_1=R_2\$. Specifically, current \$I = V/(R_1+R_2)\$ and power \$ W = I^2 R_1 = V^2 R_1 / (R_1 + R_2)^2 \$. If \$R_1\$ is "too small", the numerator drops and you lose power. If \$R_1\$ is "too big", the denominator gets too large and you lose power. The peak is at \$R_1=R_2\$. At this point you're getting 50% efficiency, since half the power is dissipated by \$R_1\$ and half by \$R_2\$. You get higher efficiency as \$R_1\$ gets larger, but less power transferred overall.

simulate this circuit – Schematic created using CircuitLab
The following image is from Wikipedia: Maximum power transfer theorem. The red line shows how the power transferred goes up and then down, with the maximum when the load resistance and source resistance match. (Although it's not the parabola you suspected.)

I find real-world applications of this interesting. If a switch is off (infinite resistance) or on (zero resistance), there is no power dissipated in the switch. But if the switch has some resistance, then it dissipates power, which is generally bad. This is why to dim lights you normally use triac dimmer switches (which rapidly switch on and off) rather than a variable resistance. But for, say, a toaster, you want its resistance to be in the middle so it heats up: too much resistance or too little resistance and you're in the low part of the curve.
Another application is MOSFETs. You generally want a MOSFET to have very low resistance when it's on and very high resistance when it's off, so you avoid dissipating power. It's the resistances in the middle that cause it to overheat.


Print Composer with semi-transparent raster but full opacity in legend

Question: I am trying to make a map with a semi-transparent (60%) raster layer overlying an areal photo (raster) base map.  This works fine and looks good but when I add a legend to display the values of the raster overlay, the legend items for the associated raster are transparent as well and end up looking like pastel versions of the colors in the raster.  Is there a way to make the legend items fully opaque while the raster is semi-transparent?  See the image below and note how red shows up as pink etc.
Comment: What GIS software are you using?
Comment: Sorry, I am having this problem both in QGIS 2.4.0 and 2.18.6
Answer: In the QGIS main project area duplicate your layer.
Set the style of one to be 0% transparency, and unclick the layer so it isn't visible.
Set the other layer to be 60% transparency as you want it, and have that visible.
Then in print composer, add your map and add the legend, you should see both layer legends with their respective styles.
Turn off 'auto-update' in the properties on the right hand side

Then select the layer in the legend that you don't want and use minus icon to remove it.

Leaving you with just the legend styled as you want it
Comment: That works.  Not an ideal work around but I get what I want.  Is there somewhere to accept your answer?  I don't see that option anywhere
Comment: There should be a tick below the up and down arrows to accept. If you have a look at other questions with an accepted answer you will see a green tick. Glad it the answer helped. Thanks


Who is the blond woman in Blame?

Question: I haven't been able to figure out who this character is; I don't think they mention her name during the movie at all.  I find it kinda strange because she is a pretty prominent character.  Does she appear in the manga?  I haven't read any of it.
Comment: In the manga, does not appear, at least in the same way she did in the movie, there are lots of electric fishers but not everyone is named.
So she perhaps appeared but not named.
Answer: According to this site (https://www.anisearch.com/anime/10968,blame/characters) her name is Fuku. Is the only info I found about her.
T

Who is the blond woman in Blame?


How to add holes in package and create elongated plated holes EAGLE

Question: I need to create this package on EAGLE but I've problems with this elongated plated holes on sides. How I can do that?
Comment: I believe you'd had to add that to the "Milling" layer. You'd also have to check with your pcb fab house if they can do plating after milling.
Answer: They are called plated slots. Whether or not you can make them however depends on your PCB fab. Some companies refuse to make plated slots, others allow it. Best to contact them directly to ask if they can do it and how they want it specified.
Some Methods:

If you add multiple overlapping holes on your design you can emulated plated slots, but these are generally not liked by manufacturers because they an cause issues with the small drill bits.

Add either 'long' style through-holes (or SMD pads on the top and bottom) and a line on the milling or dimension layers inside the pads. This will likely cause DRC errors, and you have to make sure the manufacturer knows that these are supposed to be plated slots.

The third option, and which doesn't require plated slots is to make round holes which are large enough to encompass the whole slot. So for example in the left and right holes in your recommended layout, you could use a 1.2mm plated hole placed on the centre of where the slot would otherwise be. This would provide enough space for the tabs on the component to go through the hole without needing a slot.
Answer: Create a pad (green circle) with the correct outer dimensions (oval that is) ignoring the hole in the center. Then create the outline of your hole on top of the pad using the dimension layer and a wire of zero width.
Some people add the outline to the milling layer but often that layer is ignored or overlooked when generating gerbers. I like the dimension layer because it is difficult to overlook.
I've had about a dozen of these boards manufactured with slots.


Windows 8.1 update2 on a Nokia Lumia 830

Question: The spell checker doesn't seem to be working.  I've tried to turn it on and off but i get no alternative suggestions or highlights to say a word is spelt incorrectly.  Can anyone help?
Thanks
Rich
Answer: I had this awhile back, the Keyboard language was ENG(US) rather than ENG (GB) for me. I would just double check that the language is set correctly
EDIT: This might prove useful http://www.digitalcitizen.life/add-new-keyboard-languages-windows-phone-8-switch-between-them


Python library to output images as camera

Question: I have a Python script / process that produces a series of images and I'm looking for a way to output those images to the OS (Windows in this case) as a camera device so that the images can be used in streaming applications that use a camera view, e.g. on Zoom or MS Teams. This would be similar to how the Snap Camera app works, but instead of filters applied to camera input I'd be piping in the images wholesale.
Answer: Depending on your setup, there could be an indirect way to do that, but for this approach to work, you will need a part of the display (for example, one of the screens in a dual monitor setup) to be reserved.
Disclosure: The product discussed below is from the company I work for.
If it's possible to have that part of display, here's how this works:

Display the images you need to feed to the camera on that part of the screen at the times you wish them to appear in the video feed.
Use the LEAD Screen Capture DirectShow video source to capture the area where the images are displayed.
This DirectShow component appears as a standard camera device that can be used with various programs that support cameras.

If you would like to try this approach, you can download the free evaluation of the SDK that contains the screen capture filter from this page