Tetrachords in medieval music

Question: Are tetrachords used in medieval/renaissance music the same way as modern chords are used in modern music (as a base for the melody)? And if so... how are the applied?
Comment: Please don't confuse tetrachord with chord: it is not a simultaneous set of sounds, but a theoretical construct for a successive set of sounds. I'm not sure this can be backed up, but I think of tetrachords as four notes that you could play with four fingers on one string, and the different species of tetrachords are composed of different sized steps.
Comment: What do you mean by "modern chord"?  Modern music is based on tetrachords.  The Major scale is two tetrachords separated by a whole step.  Your question seems a bit confusing to me.
Comment: Thanks for your answers, people. I thought tetrachords were some kind of chords. Now I know better... Thanks again, really appreciate it!
Comment: I think anyone with an interest in this question will find this resource called "early music sources" interesting and useful. It has in-depth explanations of the music theory of early music, but with really clear examples, audio samples, and graphics and scores where necessary, aimed at people not already steeped in mediaeval/renaissance music theory. Cannot recommend the guy enough, here's one about _hexachords_ (different but very similar to the question)  https://youtu.be/IRDDT1uSrd0 and here's a completely different one, just for interest and fantastic music.  http://youtu.be/OObAfpmUods
Answer: Since no one actually answered I'll give it a try.
A tetrachord is a specific melodic sequence of steps, specifically
Whole - Whole - Half
As an example, Do, Re, Mi, Fa, the first 4 notes of the major scale.  The next 4 notes are also a tetrachord, Sol, La, Ti, Do.  The Major scale is built from 2 tetrachords separated by a whole step.
Chords, on the other hand, are a group of notes typically played together to harmonize a melody.  They are built from consecutive thirds in the major scale.  Example the major chord is built from the 1, 3, and 5, in C that would be C, E, G.
This simple sequence is the foundation of Western Music, everything else follows from it.  Melodies are based on the diatonic scale (built from tetrachords) and chords are made from the same sequence, but from a different formula.  In a sense the tetrachord could be seen as a source for all western melody and harmony.
Yes, you will find it in medieval music in both contexts.  A follow up question to yours might be Did Medieval musicians use the same formulae as modern musicians for composing melodies and harmonies?  The formalism of modern music theory didn't really solidify until later in history.
Keep in mind that one can make up melodies and chords without knowledge of these specific sequences or formulas, and with accidentals (chromatic scale).  It appears that what is called "theory" today is a list of best practices that have evolved over hundreds or thousands of years.  There is no denying that we as a culture prefer to build up melodies and harmonies relative to the major scale (and its derivatives).  Even when we "play out" this is a relationship between what is typical vs. atypical (relative to major).
From a theoretical point of view one could say
{Tetrachord}-->{Scale}-->{Chords}
And these are used to build melodies and progressions.  There is a formulaic way to choose how a melody should be harmonized which has roots in multi voice choiral church music.  But again, these are agreed upon best practices.  Relative to modern music theory some Renaissance music does not follow modern rules and sound a little unusual.  Specifically I refer to cadences.  Many older lute pieces arranged for classical guitar do not have well defined endings, the chords circulate in a pattern and stop.  There is no 7-->8 and 4-->3, and no adherence to the principles of resolution.  They still sound nice.
Comment: Thank you very much for the extensive answer. I had no idea... I got confused by the "chords" in the word. Now I know better :)
Comment: Oh, I agree.  When I first heard the term I made the same conclusion.

Tetrachords in medieval music


When modifying a residential lease, can a separate addendum be used for each tenant?

Question: I own an investment property in Denver, CO that is currently occupied by 3 tenants who have all had some sort of falling out and as such want to terminate their lease early. The last thing I want is a houseful of people at each other's throats, so I have agreed to work with each tenant individually with respect to when that specific tenant will vacate and how much in prorated rent and fees they will be responsible for. Once everything is figured out, I will have to create an addendum to their current lease to spell it all out. Since none of them are on speaking terms and all of the agreements we could potentially arrive at could have drastically different terms, it feels like the right way to go about this is to create a separate addendum for each tenant. Is this advisable (or possibly problematic?) given the fact the original lease has all 3 of their names on it and refers to them collectively as "THE TENANT"?
Answer: What you are doing sounds enviable, however from a legal view (and bear in mnd I no nothing specifically about the law in Denver) I posit that this could be problematic - particularly if you hold a bond and/or there are damages you may be prejudicing your rights and creating a can of worms.
I would expect that the current agreement holds the tenants jointly and severally liable.  What you are proposing would prejudice your rights to go after them severally because they did not agree to the new terms.
From a practical POV there is nothing stopping you doing this, and if everything goes according to plan you will be OK.  The problem occurs if things don't.
From a legal POV I might approach this slightly differently (but be mindful that what I propose may or may not be legal in Denver) - I might allow the current agreement to be canceled by all parties conditional on each tenant entering a suitable new agreement directly with the landord (and over only the part of the property they occupy).  Once the new agreements are negotiated, I'd then notify them that the conditions of terminating the old agreement have been met.   I would then do a "final inspection" at the end of the old agreement and claim against the bond if required.
Comment: Agreed. Offering a conversion from joint tenancy to "room-by-room" individual tenancies is likely the best way forward, and likely to be supported as a standard of tenancy by existing law anyway.


BBC Sherlock - addictions

Question: Are Sherlock's addictions good for his mental condition? I noticed he avoids alcohol (rarely drinks), but used to smoke (still does, on occasion) and does / did drugs.
As if drugs and cigarettes helped him to be "smarter/ better, etc", so this is why he decided to choose them (among other addictions).
Comment: Why else would he take them? Are they good for him...of course not. I'm not clear on what you are asking.
Comment: He is just **bored**
Comment: Because in the Victorian era when Sherlock Holmes  was created drug use was legal and common, even Queen Victoria herself used cocaine.
Comment: One would assume that Sherlock's addictions are to the addictive substances which he used often enough to get addicted to.  So basically, Sherlock, like many other people, chose some dangerous substances to try while assuming that he was too smart to become addicted to them, and then those substances chose him to be an addict, so to speak.  I note that many people start using tobacco, which though legal is extremely addictive, when they are foolish preteen children and become addicted to it as children, and Holmes could be one of them.
Answer: "What do you get for the man who has everything?"
This is frequently said of those whose wealth prohibits his friends from buying gifts.
Holmes' wealth is sheer intelligence.  A man with boundless money could go mad because acquiring possessions only fleetingly will make him happy.  Holmes, on the other hand, is left a prisoner to the musings of his mind.
It's understandable that he would rarely take a drink; alcohol is a depressant, and leaves a man tired and thinking slow.  Nicotine on the other hand is a stimulant.  This would get his mind racing to places he might not otherwise.  And opium is ratcheting the high to highest levels, causing euphoria and hallucinations.  These are the vices of a man who has everything.

BBC Sherlock - addictions


Compressed Air Engine

Question: Is there any efficient way of using a large volume but low pressure (<2 bar) stored compressed air, either to drive an engine or some other application?
Comment: Google "blowdown turbine"
Comment: Thanks for the Prompt info sharing.
Answer: To store a large volume of low pressure air requires a truly gigantic holding tank which would be completely uneconomical to build and operate. Consider the following: a wind turbine is the ultimate in extracting useful work from a high flow rate of low density working fluid (air) driven by an extremely small pressure difference. Assume a 100 foot diameter turbine feeding on air flowing at 22 feet per second, meaning that in one second, 173,000 cubic feet of air goes through it. In one minute, ten million cubic feet go through; in one hour, 620 million cubic feet and in 24 hours, 14.9 billion.  That's a tenth of a cubic mile of air to run the turbine for one day and you want to store it all at a fraction of a PSI for the source pressure? From the standpoint of mechanical engineering, you'd never do it that way.
To make it economical dictates that you increase the energy density of the storage method which can easily be done by compressing the air to high pressure and releasing it at low flow rates instead of trying to do the same with low pressure and high flow rates.
Answer: welcome on this SE. Your question might be a little vague for Engineering SE, but here is a possibility:
You can use this volume of air as a refrigerant: You put it at ambient temperature, wait for the air volume to come to the ambient temperature, and then you put it close to a volume to cool down: the difference of pressure will cool down the volume of air, and heat transfer will do the rest.
Comment: This feels like a brainstorming session, which SE isn't the best venue for.  In terms of using it as an engine, sure, but the stored energy will be low per unit, so for an engine to do meaningful work it would need large pistons.
Comment: @ScottDunnington Yes this looks like brainstorming, that is why I warned the OP about the question being "vague". About using as engine, I think it could more efficient in the work I described (not taking in account it is a totally different output)
Comment: As you rightly said typically Heat engines require larger compression ratio for good efficiency and in this case energy per unit volume is also less.  Thanks for indicating a possible use as refrigerant..
Comment: I am envisaging rather theoretically of extracting heat from a low temperature but high Heat capacity medium using "Second law thermodynamics", where external work done on the closed system will transfer heat  in the reverse direction. I theoretically arrived the heat thus extracted can be used to raise the pressure of air to 2/3 Bars whereas the COP of the system is of the order of 300%, i.e. one Joule work done would extract Four Joules of heat out of the medium.
Comment: But the limitation is that the heat extracted can only be used to rise the Air pressure to at most 2/3bar and the COP will reduce tremendously for larger pressure ratios. Hence I was wondering whether there is any
use of storing the extracted energy as a low compressed air!! Thanks again for your reading and patience.

Compressed Air Engine


What are today's methods in calculating the Local Magnitude of earthquakes?

Question: I'm no expert and barely have any idea about this. But I want to know if the methods in calculating the Local Magnitude can only be done manually? I mean manually by first reading a seismograph, identifying the distance of the epicenter using the distance between P-S waves, and then measuring the height of the highest amplitude. Or are there software, APIs, and etc that can do this automatically by just providing the seismograph data. Or there's no way to calculate the Local Magnitude without a human input?
Comment: This procedure can be done automatically, but unanticipated errors will creep in. Usually, some binning/averaging is done to suppress these effects.
Answer: According to the equation for local magnitude calculation I give my answer: Of course there is a lot of algorithms for auto-picking, in fact, the magnitude value that you see in the first report (immediately) after an earthquake is (almost always) an automatic calculation. https://academic.oup.com/gji/article/199/1/368/731808. However, the P and S picked time is checked but humans in order to improve the accuracy. I think the human verification is always necessary and obligatory, because some earthquake are complex signals. !. Moreover, the point here is not the human-based method, I thing it should be focused on the quality control system.


What happens if I don't update my plugins?

Question: If I don't update the plugins for years, what happens? Because I have an e-commerce website and often when I update a plugin I have errors and I lose customers. Is something bad happening if I don't do it? Thank you!
Answer: I personally disable all updates; themes/plugins/core, too many times I was burned with erros in the most inconvenient times possible.
Now I do manual updated for each site after I checked in a development environment. after im sure that everything works and I fixed every bug that happened I update the live site.
Now I have far less problems.
The down side is that updated provide the latest and greates (usualy) options, better code, better security and so on.
You can have a plugin that was not updated in a year with a vulnerability that was already patched, in that case you leave yourself open to attacks.
Its up to you to decide what is the best approach to updated.
I disable every update and do regular checks once a week.
The number of calls I have about update problems are far lower now than when the updated were automated.
Comment: Thank you for your replay, I have one more question, how can I activate development environment? I made all updates in the live site. I didn't know that exist a development environment
Comment: @RăuțuDenis You need to create one yourself, some hosting provide a one click install for staging/development environments. Its basically copy paste your current folders/files and DB to a new location and doing the testing there first
Comment: Thanks a lot. Have a nice day!
Answer: While I would not recomend automatic updates for the reasons buttered_toast covered. you need to keep in mind that postponing updates means that you develop a "technical debt".
For example lets assume that you do not upgrade for 3 years, but after 3 years you find a plugin you wish top use but it requires an higher version of wordpress. Now you need to check if the rest of your plugins and themes are compatible and test them and then a simple plugin install might become a complex operation of rebuilding or at least test all of the site again.
Usually at the point you need to handle your technical debt you actually don't have the time to properly figure out all the changes in the other plugins and properly test everything which makes it a stressed experiance. It is better to try not to accumulate to much technical debt in the first place and handle upgrades at some reasonable intervals.
Answer: The best practice is to keep all plugins up to date. If you aren't able to do that, then you should read the release notes for any updates you're opting out of, to make sure they are not addressing serious issues.
Just recently in the past week, a critical flaw was discovered in WooCommerce (and promptly patched). If you are not updating your site and not staying informed about critical updates, then you are exposing your site and its users to far worse problems than plugin errors.


Laminar Flow From Outdoor Faucet

Question: I ran across a video recently that really caught my attention. It's been circling the internet over the past couple weeks, but I'm trying to figure out what's going on. Basically, it's a video of an outdoor water faucet which has water slowly running out of it. The water appears to be fake, almost made of plastic or glass, because the flow is so steady, but then the person recording puts their fingers into the stream and breaks it. All of the various people who have posted the video title it as being "laminar flow," but I'm not really sure if that's the correct terminology since the flow doesn't appear to be completely uniform. Many people believe that the video is fake, but it's so perfect that I don't think that could really be true. This youtube commenter created a great post that reflects my thoughts on that:

For people that think this is edited/frame edited.. the proper term is Compositing or VFX (Visual Effects).
  I'm a compositor and I have to say that if this isn't real, then whoever composited this has incredible talent. I don't see any artifacts that lead me to believe this isn't real.
  You would have needed to make a 3D rendering of the stream, make a camera movement path to match the movement in the video, create refractions through the 3D rendered stream, match the focus changes throughout the video... and a bunch of other things such as colour correcting and whatnot. All of this isn't difficult to do fairly well. However, this isn't just "fairly well." This is perfect. Matchmoving is crazy difficult to make look THIS good and the amount of time to tweak it could take a lifetime (and possibly admission into an insane asylum). And it's especially difficult to matchmove on a lower quality camera that has weird warping effects added to camera movement. You'd have to emulate not just movement but the camera artifacts.
  On top of that, perfect focus matching?
  Watching it at quarter speed I also noticed a detail. If you notice very carefully when he puts his hand in the stream you can see the wavy effect called the "Rayleigh-Plateau Instability." This happens in the stream right above where the water meets the hand. This is an incredibly subtle and unnoticeable detail that you can only see at a fraction of normal speed. I find it highly implausible that someone would go THIS detailed.

Anyhow, I'm basically wondering if it is possible for a stream of water to behave this way in the real world. If so, what is it the phenomenon called, and is there any way that I could possibly recreate it? These are the types of projects that I love and would really like to be able to recreate a stream of water like this if it is actually physically possible. Thanks everyone! Here's the link to the video: https://youtu.be/Ske2fgZgPs8
Comment: If you're interested in the Rayleigh-Plateau Instability effect in a laminar flow of water, there's an interesting pop science video here: https://www.youtube.com/watch?v=DvtbQs7hWXw
Comment: ..."laminar flow," but I'm not really sure if that's the correct terminology since the flow doesn't appear to be completely uniform."  Laminar flows do not have to be uniform. Flows over entire wings can be completely laminar under appropriate conditions, for example.
Answer: That water is near freezing, judging by the snow nearby. This kicks its viscosity up to abnormal levels and strongly damps out any vorticity and flow instabilities.
If you are careful pouring motor oil at room temperature, you can get the stream of falling oil to exhibit creepy consistency too.

Laminar Flow From Outdoor Faucet


What is the difference between yoga and yogasana?

Question: We keep people using the terms "Yoga" and "Yogasana" interchangeably.
Are they synonym?
If not, what is the difference between the two?
Comment: Yoga is of soul but Yogasana is of body. Yogasana is the path but Yoga is the fruit. https://hinduism.stackexchange.com/a/36473/16530
Answer: You would have seen people performing these kind of postures-

In simple terms, this is Asana; more precisely Yogasana, since asana is part of Yoga (both asana and yogasana mean the same)
Pathanjali's sutra for asana is-
स्थिरसुखमासनम्
स्थिर - steady
सुखम् - comfortable
आसनम् - asana
Which means a posture which is steady as well as comfortable is an Asana.
Now, what actually is Yoga?
Yoga is a discipline or practice, consisting of 8 stages, to attain higher consciousness. And Asana is one of the stage in the Yoga. (hence Asana is also referred as yogasana)

Pathanjali's sutra for yoga is-
योग: चित्त-वृत्ति निरोध:
चित्त - mind
वृत्ति - nature
निरोधः- resist
Meaning - mind is often compared with monkey for the reason mind's inherent nature is as mischievous as a monkey, doesn't listen to anyone and hard to focus on one thing. So resisting mind from its inherent nature and helping it to keep calm and focused, is what yoga.
So above are the 8 stages you have to go through and master to achieve that state of mind.
One has to complete a given stage to proceed to the next stage. It is designed in such a way that the previous stage helps in progressing on the next stage. Say, you have to perform Pranayama, for which you need to sit in a yogic posture (Padmasana, swatikasa, vajrasana, bhadrasana or veerasana). So unless you have mastered asanas, you can't sit in those postures for significant time without being distracted because of body ache. And also you can't maintain that proper physical posture which is required for Pranayama. Similarly, pranayama lays a stepping stone for the subsequent step, Dhyana by grooming on controlling your mind.
It gets tougher as your move up the ladder. Since the thinks that you work on changes from physical body towards your mind.

Since Asana helps in maintaining a health body, lot of people practice it and it has gained popularity. And also it is the easiest one (relatively) among the rest of the stages. As a result Asana has been used as a misnomer with the word Yoga.
Answer: Only if the vehicle like body is healthy, practicing yoga becomes more than 3 times easier, wiser - hence Yogasana is very critical part of the Yoga system. If the body is fit, immune, self can be firm to complete all the roles and responsibilities it's obliged to, without much resistance.
Thus, yogasana is not completely Yoga in itself, it is simply one part of Yoga.

Yama - forsaking bad deeds.
Niyama - performing good deeds regularly.
Yoga Aasan- keeping the body healthy.
Pranayam - controlling the breath.
Pratyahara - removing one's faults.
Dharana - bringing the chitta to focus. (Until this point the feeling of doer is present in a subtle form)
Dhyan - attain the state of meditation if it happens.
Samadhi - attaining oneness with Paramatma.

The main objective of Yoga has always been to reduce the body consciousness inside a person and increase the soul consciousness. The soul does not have any problems, all problems are of the physical body. When there will be no body consciousness, there will also not be any problems of the physical body too.
Using meditation as a mean, the soul consciousness should be made to increase. Here, simply by maintaining a sense of surrender of thoughts, errorneous emotions one can gradually attain the state at the eighth level of Ashtang Yoga (8-limbed yoga or union) which awakens the innate humanity residing within man.
Comment: Welcome to Hinduism Stack Exchange! We insist on citing sources to maintain some quality standards. Cite some reliable sources (preferably scriptures).


wiring a arduino led project

Question: I am moving a project from breadboard and jumper cables.
It light a bunch of LEDs with different sets running of many almost every pin.
I need a few meters of cables.
I will a resistor on each led.
I have no idea what kinda cable/wire to use and googling cable gets me nowhere.
What kinda wire do people use?
Comment: I don't quite understand your question, but would [ribbon cable](https://en.wikipedia.org/wiki/Ribbon_cable) fit the bill?
Comment: Otherwise, describe what sort of cable you're looking for (presumably you have some sort of idea) and someone may know what it's called.
Answer: When choosing wire for your project the main consideration is the amount of current. Second would be the distance.
For LEDs the current is generally low (milliamps) so something like a 20 or 22 gauge wire would be fine. You should be able to get it at a local hobby electronics shop or Amazon of course.
FYI, Wire gauge numbering is such that the lower the number the thicker wire. Thus 20 is thicker than 22.
You may find this AWG (American Wire Gauge) table helpful: http://www.powerstream.com/Wire_Size.htm
Comment: With careful choice of wire thickness and length paying close attention to the resistance-per-meter it may be possible to do away with the LED resistors entirely and use the resistance of the wire instead.

wiring a arduino led project


app language, should it be specified by the user on first use or to be in settings page?

Question: if mobile app supports many languages, should I ask the user to specify the language he wants on the first use or to set a default language based on the device language and let the user change it later from app setting for example?
OR There are different suggestions ?
Comment: It depends on the market and the app. Is the app content heavy (stories), is content separate for separate language settings (book store, stack overflow in German vs English)? Does the app support languages people in the market region would prefer over their device language? Would you mind briefly describing the functionality and the region?
Answer: You don't want to make the user think about this. They have already set up their device in their preferred language. I doubt any one would bother to change the language of an app (unless your app is a language learning tool)
So set the app language based on the device language. But don't take my word for it - by all means create a language setting in your app so that the user can change the language to something else, then monitor if anyone actually uses this setting. This way you can make the decision based on hard data rather than my opinion.
If no one changes the language in your app, you can quietly get rid of the app Language setting in a future app update.
BTW You rarely see a language setting in mobile apps.
Answer: Asking for details you already know is setting users away from the goal.
Avoid doing that, unless choosing a language adds some specific value:

For a translating application, user might know English, but it's not their native language. Therefore the device might be in English, but user would prefer to translate from a specific language.
For an application with a sophisticated language.

So, don't ask for the language unless you can justify that or there is no way to obtain the information otherwise. For example, in case user's device language is not included in your supported languages list.
Answer: I think the best idea is to let the user be involved in choosing the preferred language at the first login. Even before the login page, it would be nice if I can choose the language of the app that I have downloaded at the time I hit it to open for the first time.
Other researchers say it would be optimal if we followed the localization rule. Since I live in Germany, I assume that downloading any app from the online store will be directly opened with German language preferences.
As you see, it depends on at many factors, such as the target audience that you want to target and the functionality of the app itself.


How to control multiple OpenVPN instances on the same server?

Question: We have Centos servers running multiple daemons, up to 3 on each server. I have looked at the the rc.d init scripts and see no way to control the daemons independently. We would really like to be able to restart one tunnel without affecting the others. Is this possible? Where should we be looking?
Answer: The initscripts in Debian and Ubuntu for openvpn allow single instances to be managed by naming them on the command like:
<code>/etc/init.d/openvpn start vpn_name_1
</code>
and
<code>/etc/init.d/openvpn stop vpn_name_2
</code>
If the script(s) that come with the CentOS openvpn package do not support this then you could perhaps copy the logic from the versions in Debian/Ubuntu (don't copy the whole script though as there may be other distro specific differences to worry about).
Answer: We run 3 OpenVPN instances in our setup, and we just use:

/usr/local/sbin/openvpn /etc/openvpn/1.conf &
  /usr/local/sbin/openvpn /etc/openvpn/2.conf &
  /usr/local/sbin/openvpn /etc/openvpn/3.conf &

Of course each instance is running on a different port and has different settings and then you can kill each instance separately and start them up without affecting the others.


Deriving cross product from angular momentum algebra

Question: Is it possible to derive:
\begin{equation}
\hat{L}=\hat{r}\times \hat{p}
\end{equation}
from the angular momentum algebra:
\begin{equation}
[\hat{L}_i,\hat{L}_j]=i\ \hbar\ \epsilon_{ijk}\hat{L}_k\ ?
\end{equation}
I have read somewhere that commutation relations of the form
\begin{equation}
[a_i,b_j]=\epsilon_{ijk} c_k
\end{equation}
admit a "natural rewriting in terms of cross products", but there weren't any details about this statement.
Answer: It's not possible to derive the orbital angular momentum $L = r \times p$ from the $\mathfrak{so}(3)$ commutation relations alone, since the spin operator $S$ also fulfills the same commutation relations, but certainly is different from $r \times p$.
Comment: That's exactly what I would have written, but I don't know if more needs to be said to explain why or how we know that spin is different.
Answer:
I have read somewhere that commutation relations of the form
  \begin{equation} [a_i,b_j]=\epsilon_{ijk} c_k \end{equation} admit a
  "natural rewriting in terms of cross products", but there weren't any
  details about this statement.

This "natural rewriting" of the canonical commutation relations for angular momenta in term of cross products is:
$$
\vec J \times \vec J = i\vec J
$$
I.e., the "natural rewriting" refers to rewriting the commutation relations themselves in terms of a cross product, not rewriting a single angular momentum in terms of cross products of other quantities.
Explicitly, for angular momentum:
$$
\vec J \times \vec J = i\vec J
$$
Thus:
$$
\epsilon_{ijk}J_jJ_k=iJ_i
$$
Thus:
$$
\epsilon_{ilm}\epsilon_{ijk}J_jJ_k=i\epsilon_{ilm}J_i
$$
Thus:
$$
J_lJ_m-J_mJ_l=i\epsilon_{ilm}J_i
$$
I.e.:
$$
[J_l,J_m]=i\epsilon_{lmi}J_i
$$
In terms of your "a", "b", and "c", the analogous "natural rewriting" is:
$$
\vec a\times \vec b + \vec b \times \vec a=2\vec c
$$
You can see this by considering:
$$
(\vec a \times \vec b)_i
=\epsilon_{ijk}a_jb_k=\epsilon_{ijk}(b_ka_j+[a_j,b_k])
$$
$$
=-\epsilon_{ikj}b_ka_j+\epsilon_{ijk}[a_j,b_k]
$$
$$
=-(\vec b \times \vec a)_i+\epsilon_{ijk}\epsilon_{jkl}c_l
$$
$$
=-(\vec b\times\vec a)_i+2\delta_{il}c_l
$$
$$
=(-\vec b\times \vec a +2c)_i
$$
Comment: How is $[a_l,b_m]=a_lb_m-a_mb_l$?
Comment: whoops, good question... screwed that up somehow... Let me fix it.
Answer: $$\begin{align}
\left[\hat{A}_{i}, \hat{B}_{j} \right] & = \epsilon_{ijk}\hat{C}_{k}, \\[3mm]
\hat{A}_{i}\hat{B}_{j} - \hat{B}_{j}\hat{A}_{i} & = \epsilon_{ijk}\hat{C}_{k}, \\[3mm]
\epsilon_{ijn}\left( \hat{A}_{i}\hat{B}_{j} - \hat{B}_{j}\hat{A}_{i}\right) & = \epsilon_{ijn}\epsilon_{ijk}\hat{C}_{k}, \\[3mm]
\epsilon_{ijn}\hat{A}_{i}\hat{B}_{j} - \epsilon_{ijn}\hat{B}_{j}\hat{A}_{i} & = 2\hat{C}_{n}, \\[3mm]
\left(\hat{\vec{A}} \times \hat{\vec{B}}\right)_{n} + \left(\hat{\vec{B}} \times \hat{\vec{A}}\right)_{n} & = 2\hat{C}_{n}, \\[3mm]
\frac{1}{2}\left(\hat{\vec{A}} \times \hat{\vec{B}} + \hat{\vec{B}} \times \hat{\vec{A}} \right) & = \hat{\vec{C}}.
\end{align}$$
due to the fact that $\epsilon_{ijn}\epsilon_{ijk} = 2\delta_{nk}$.
Comment: What is wrong with this derivation?
Comment: Besides the fact that sometime you explicitly write the summations and sometimes they are implicit, there's nothing wrong with the derivation. Probably people are down-voting because there is no explanatory text to go along with the equations... or maybe the explicit/implicit thing is confusing...


Handwriting in Japanese

Question: I've heard of the terms brush-up, release, stop, etc. When natives write, do they follow this rules? Is it widely known? Would natives know if I did a release, stop, etc? Is it okay not to use it as long as the character is identical to the original?
Answer: Short answer:

A well trained eye sees deviations even if we foreigners eyes think "it is identical"
Exposing one's hand writing to others is nowadays almost as rare in Japan as it is in many "Western" countries

As to 1:
It is funny how our brains work also when interpreting what we see; we see some very subtle differences when we have learned to focus on them, while we really overlook others.
As far as I know, a person who has gone through the Japanese school system has seen the same characters so often and has has so many repetitive excerices of writing, that he/she is able to notice differences which we with less of that experience can't. (Compare that to "all the Japanese look alike when seen by foreigners" and "all the foreigners look alike" when seen by Japanese)
As to 2:
(Even the use of fax machines in homes, is slowly but surely disappearing even in Japan...). In addition to not exposing one's handwriting, and thus not having to interpret the handwriting of the others, also for one's own use, the need of it is reducing. But, still, you write the way you have gotten used to / been trained. (Not only the Japanese, at least I write O,o and 0 counterclockwise because I am used to do that way, and, presumably this comes from school. (And the small alpha (α), while learning that a lot later, goes "clockwise" (ie starting from top-right)
Answer: How accurate your letters are doesn't matter so much. It is widely known because there's 書道(syodou) culture which is about how to write letter nicely. Japanese these days don't care about how your letters look like if your letters are not hard to recognize.

Handwriting in Japanese


PTIJ: I live in Australia and am upside down. Where should I put my tefillin?

Question: Should they go on my hands or my feet? I usually write with my right foot.

This question is Purim Torah and is not intended to be taken completely seriously. See the Purim Torah policy.
Answer: The feet are a perfectly valid location for Tefillin. See Rambam, Tefillin 4:26:

. וְכָל הָרָגִיל בִּתְפִלִּין מַאֲרִיךְ יָמִים שֶׁנֶּאֱמַר (ישעיהו לח טז) ״ה׳ עֲלֵיהֶם יִחְיוּ
The entire foot is for Tefillin, and [one who does so] will have lengthened days etc.

As well as Eruvin 96a:

דתניא מיכל בת כושי היתה מנחת תפילין ולא מיחו בה חכמים ואשתו של יונה היתה עולה לרגל ולא מיחו בה חכמים מדלא מיחו בה חכמים אלמא קסברי מצות עשה
Michal the Kushi would don the Tefillin and there was no protest by the sages. The wife of Yona would don it in the foot and there was no protest by the sages. Since the sages did not protest, they believe it to be a positive commandment.
Comment: kal vachomer... if in the N Hemisphere the sages allow it and approve etc. how much more so in the S hemisphere?
Comment: They didnt live in Australia. So the answer has nothing to do with where you live. I would add the opposite. That was the reason the sages didnt protest.
Answer: Since you are in Australia, it would also be night time, and one does not wear tefillin at night.
Comment: I respectfully disagree with this answer.  It implies that at McMurdo Station, one may not wear tefillin the entire Antarctic night.  I believe it's been established that in conditions where sunrise and sunset vary dramatically from local time, one should don tefillin (and do other time-of-day-bound mitzvot) according to the official local time.
Answer: Yes, on all שלש רגלים it is prohibited to don the Tefillin.
Comment: Darn, i was hoping maybe on my 3rd foot...


What tribe were Eldad and Medad from?

Question: I have been trying to find biographical information about Eldad and Medad but cannot seem to find a source which states which tribe they are from. The Baale Tosfot - Daat Zekeinim says they were related to Moshe but does not cite a source for this.
Answer: According to Bamidbar Rabba 15 19, Eldad was Alidad ben Kislon and Meidad was Kemuel ben Shaftan.
That would put Eldad as the Nasi of Binyamin and Meidad as the Nasi of Ephraim as found in Parshas Masei 34 vs 21 and 24.
The idea that they were related to Moshe is found in Targum Yonasan Bamidbar 11 26. There we see that when Amram divorced Yocheved she had these two sons from Elitzaphan ben Parnech. In Bamidbar 34 25 we find him listed as the Nasi of Zevulin.
And then there is the Daas Zikeinim mentioned by the OP found in Bamidbar 11 27. There we find the idea that Amram fathered them after Har Sinai when he and Yocheved heard they couldn't be married since she was his aunt, and he went and married a different women.
That would of course put them in the tribe of Levi.
(Interestingly, a source mentioned in the D.Z. calls them paternal half brothers of Aharon, and doesn't mention Moshe.)
The D.Z. also quotes the idea previously mentioned from Bamidbar Rabba.
Comment: "Yocheved had them after Har Sinai" so they were less than a year old when they received their nevuah?
Comment: @Heshy Basically. I know it sounds strange. I'm quite certain I have the source written down somewhere.
Answer: This link explains a lot and brings the sources from the answer above as well, but it also adds a footnote to Igrot Kodesh Vol 15 letter 5537, where the Lubavitcher Rebbe answers when Amram might have separated from Yocheved and fathered Eldad and Medad, according to the tradition brought by the Daas Zekainim. Basically, it seems like he answers that Amram may have become aware prophetically of the future issur of arrayos and separated from Yocheved again, at some point after Moshe was born (perhaps learning about it through Moshe.)
https://www.chabad.org/parshah/article_cdo/aid/4407977/jewish/Eldad-Medad-The-Mysterious-Prophets.htm
Igrot Hakodesh Vol. 15 linked here: https://www.hebrewbooks.org/pdfpager.aspx?req=15912&st=&pgnum=236

What tribe were Eldad and Medad from?


makara sankrAnti and sun's rAshi

Question: When is sankrAnti celebrated? If the sun lies in dhanuSh-rAshi at sunrise and only crosses over to makara afternoon (as is the case in 2018 relative to India time), is sankrAnti celebrated on that day itself or on the following day? What are the pramANa-s?
Comment: The worship of the Sun is done, as per practice, when the sun starts its Uttarayan Journey.  Normally in South India all poojas are performed in the forenoon.  One of the exceptions is the Makara Sankaranthi Pooja.  Sankaranthi would be celebrated on the day sun starts the Uttarayan Journey and not the next day.  I am placing a comment, because I do not have any scriptural references handy.  Would be glad for enlightenment on this subject.
Answer: It's been rather tricky this time :). In general, we perform puja in Uttarayanam. As long as the sun transits over before sunset, the puja is done on the same day. This time, according to Srirangam Vakya Panchanga, it's approx. 17:05 IST (Drik Panchanga: 13:50 IST). We're doing the puja at ~3 pm IST, so that the puja will be over before Pradosha time (It's Pradosha day as well!). Whenever there are such complexities, it's just convenient to follow whatever the Purohit says!
Happy Sankranti! नमः सवित्रे जगदेकचक्षुषे!
Comment: What ayanAmsha does Srirangam Vakya Panchanga use? Reminds me of https://twitter.com/ShriramanaS/status/949644728592580610

makara sankrAnti and sun's rAshi


Is there a program that can change monitor color temperature for lighting?

Question: I'm shooting a scene for a film where the actor will be placed in front of a computer monitor. I want to use the monitor to light the actor, but I want to be able to adjust the color temperature to get the look I want. I have F.lux (https://justgetflux.com/), so I know changing monitor color temperature is possible, but I want to be able to control it. Preferably the program would be free, and I would be able to adjust the temperature in real time.
Comment: I was planning on using a white image fullscreen, and then being able to adjust the temperature from there.
Comment: What do you want to show on the screen?
Comment: You *can* use flux to set your monitor temperature manually ... also, what monitor are you using? Mostly all mordern monitors have in-built options to change color saturation, temperature, brightness ... or, even easier, couldn't you just use an orange/red/whatever-colored image in fullscreen mode?
Comment: I have an older AOC monitor, the settings on it aren't very in-depth. The main issue is I want to be able to adjust the temperature live so I can see what it looks like, which is why I want a program. I did look into f.lux settings a little more, and it allow some modification, but I'd like something a little more flexible if anyone knows of something like that.
Answer: Here is a hack. You can use Blender and the Blackbody Node of Cycles Render Engine. Following example shows a realtime viewport animation of the color temperature in kelvin:

Create some geometry (e.g. a plane) as light emitter
Setup an Emission shader
Create a Blackbody node and plug it into the Emission Color
Position your camera
Switch your Camera by pressing Numpad 0
Set the Viewport Shading to Rendered or press F12 to render the image

blend file

Renderings

2000K

4000K

6000K
Comment: Ya, good idea.  If you can't adjust the monitor, then send it something other than pure white.  Blender seems like HUGE overkill.  I would have just booted Linux, logged in remotely, and done `DISPLAY=:0 xsetroot -solid '#fff'` to set a solid white background.
Comment: @PeterCordes Thanks Peter. You are right, OP was asking to control it by kelvins and I thought Cycles is physically accurate and have an instant viewport interactivity/rendering, so it could work :) Why not converting your comment into an answer? I would like to upvote it ;)
Comment: sure, why not? :P
Answer: If you can't adjust the monitor, then send it something other than pure white.
@poor already posted an answer to do this with Blender, but that seems like HUGE overkill.  I would have just booted Linux, logged in remotely, and done DISPLAY=:0 xsetroot -solid '#fff' to set a solid white background, or any other color I wanted.
And there's probably something you could run to open a fullscreen window with a color of your choice, to save the trouble of switching to a window manager that didn't clutter up the screen borders with stuff.  Maybe a screensaver type of program?
I can't think off the top of my head what would give you a GUI color adjuster that would change most of the screen in realtime.
Comment: @Gin-San: If it was a computer I owned, it would already be running Linux :P  Obviously go with whatever OS you already use.
Comment: Using a seperate OS seems even more overkill than installing a freeware program tbh
Comment: You could additionally mention that it's possible to boot it via usb stick.
Answer: Thanks for the other good answers. Here is what I ended up doing.
I created a blank white html page and made it fullscreen, and then used f.lux to adjust the color temperature. It worked for me, but I should point out to anyone looking to use this solution in the future that it isn't perfect. F.lux doesn't give a very broad range of color temperatures. They were enough for my purposes, but someone looking for a very warm or very cool look might not be satisfied. In addition, f.lux changes the color temperature for the entire desktop on all monitors, so if you have something color-sensitive running during the shoot, like using the computer as a monitor, your colors will be off on that as well.


How to broadcast on Instagram via obs?

Question: I've seen a bunch of paid services that provide the ability to stream to Instagram via obs, but how are they arranged? How can I implement this myself?
Answer: A quick google search gave me dozens of options. You can use yellowduck for example. Here's a tutorial on how to use it. An alternative is promovgram. There really are a lot of options, so I would recommend just googling yourself.
Comment: You are not answering the question posed. I'm asking how exactly to implement this myself, and not use a third-party service
Comment: oh right, sorry for misreading. From what I've read, you need to use an API from instagram which only seems to be accessible to companies that apply for it.

How to broadcast on Instagram via obs?


Resources for text classification algorithms

Question: I'm mining raw Facebook comments (irrelevant) and i am looking for an algorithm that can classify their context as negative/positive/neutral. So you can think of the output in the form of two columns. First column the comment (exists), and second column its classification. If possible i'd like for the algorithm to be able to process the sentence as is (e.g. not having to remove stop words etc). Can someone recommend any resources that i can refer to? I have no problem doing this in either Python or R.
Thanks
Answer: So, I believe what this question is asking for literature around sentiment analysis of Facebook comments (positive/neutral/negative) sentiment.
There is quite a good paper on this using an encoder-decoder architecture here: https://www.aclweb.org/anthology/Q18-1002/
Answer: I would look into Python's spaCy for sentiment analysis.
You might also find useful this link https://notebooks.quantumstat.com/


Server rack recommendations

Question: I'm putting servers on a rack for the first time, and am thinking a 4-post open frame rack is adequate for my needs.  I'm putting in a few HP DL 385's and a few other things.  What I'm wondering is if there's reason to be picky about the rack selection.  I'm not concerned about heat or size - just installation and fit.  Any recommendations or considerations?
Comment: Do you have any dell rackmount servers? They tend to be longer and require adapters or a deeper rack to get the rails mounted correctly.
Answer:
It may sound like a joke, but one important consideration are the holes of the frame; there are two types, a relatively uncommon threaded hole and the standard square hole for cage nuts.  As most devices you can buy are prepared for the square hole, this is a safer bet. But even then, be careful when you buy devices.
If you anticipate any growth, you should consider what kind of accessories are available for the rack you chose. Many companies (like APC) offer whole systems of devices like lights, door switches, PDUs etc.etc
If you decide to buy a rack with doors, consider the depth of the rack and make sure you don't buy a 60cm version for cabling and networking, as you won't be able to close the back doors with a server in it.
Comment: +1 Also consider wider racks with some extra space on the sides for cabling and/or utility devices if this is the only rack you'll have - perhaps some panels and other stuff want to live in it ^^
Answer: Some things I have learned looking after a smallish machine room of 6 cages:

I have had good luck with the APC netshelter, 42U unit.
Make sure it's long enough to accommodate your rackmount equipment
Make sure you have the rails for your equipment - they are often mated to your case
Account for space eaten by UPS unit(s), I put mine in the bottom of the rack as they are heavy
Take into account power cable lengths; typical server power cables are usually not long enough to reach servers in the top 8 or so of U the rack, you may need to get a power strip to distribute power
Make sure there is enough room behind the unit so that you can get in behind to cable, power down and generally fiddle with stuff
Make sure there is reasonable ventilation in back as all the heat is going to be concentrated to some degree
Most folks don't leave spaces in the rack between units as  the only airflow that matters is what can actually be sucked in the front of the rack to cool the parts inside
Never rackmount new gear alone. This stuff is heavy and bulky. Have at least an extra set hands to help: no need to lose toes, hands etc or damage equipment especially when racking in the upper portion of the cage. Get a lift unit or scissor table to help if you can
Make sure you have the right kind of power plugs at the installation - rackmount equipment doesn't always have the nema office power plugs, especially the 30+ amp rackmount ups gear - no bigger bummer than putting it all together and have no way to power up :(

Hope this helps.
Comment: All of this is sound advice, plus if you're mounting server kit don't get a rack with inadequate door ventilation. Some racks are fitted with perspex on the front door and fewer air vents, and are better suited for comms and networking gear rather than active CPUs. The stuff you want will have a full-door grille.
Answer: Not joking here either if you are going for a freestanding rack make sure it has some kind of stablization (some people call it a kick-stand lol), epsecially if it has wheels.
Answer: When you bend down to pick something off the floor make sure that the rails are pushed back into the rack.  I made this mistake once and stood up into the rails resulting in my one and only IT injury stitches to the head.
Comment: Especially that keyboard tray, which tends to be pulled out when you are physically troubleshooting those servers. Not only can you whack your head against the sheet metal and get a scar, but you might be completely disoriented while stumbling around for 10-30 seconds, swearing at the top of your lungs the while time. And it might be 2AM in the datacenter, and you are all alone, looking for a tissue, bandaid, paper towel, or anything. NOT THAT THIS HAS HAPPENED TO ME, or anything.
Answer: I don't have any specific recommendations that haven't already been covered but when I was faced with a similar situation I paid a visit to a local company (Hallam Oz) that makes racks and rack fittings. They will even custom make them if required. On that visit I took a slide with me so that I could actually see how it would fit. It seems that apart from the more obvious issues, such as the holes, the pillars come in a variety of profiles and not all slides will readily mount all racks.

Server rack recommendations


In HaxeFlixel, how do I avoid hard-coding dialogue?

Question: I'm planning to develop a visual novel in Haxe Flixel and wanted to know if there is a easier way to add dialogue than to hardcode them in every square. I don't know if I can import a txt file with the dialogues or something like that so I can simple change the txt file instead of have to check the code for every typo.
Answer: openfl.Assets.getText("assets/dialogs/exampleDialog.txt"); should do the trick.
Comment: While the answer could be correct, it's very vague and I can't find any information related, if you could be more specific with your answer and offer a brief explanation I could chose your as correct. Thanks!
Answer: Gama11's method is the one I would use personally. Basically you put all of your text inside a text file dialog.txt and split each dialog up with some special character or character sequence (i.e. @@).
------ dialog.txt ------
This is dialog for box 1.@@
Dialog for box 2.@@
And so on...@@

inside of your game use the following:
var dilog_boxes:Array<String> =
    openfl.Assets.getText(AssetPaths.dialog.__txt).split("@@");

now all you need to do is access the array for each specific block you need. If you need text for block 1, use dialog_boxes[0], block 2 is dialog_boxes[1], etc.
Answer: You'd better use a script engine to do that. There are plenty of script engines in Flash AS3, but for Haxe, all I know is hscript. However, hscript doesn't have the handy ability to suspend in the middle of the scripting, which  I think is very important in your case.
So you may need to find a script engine in Haxe that can suspend in the middle of its scripting like the BISE engine in AS3, or write your own in Haxe (Although I'm forking hscript to support that feature, I'm not sure when it'll be ready for a release), or switch to AS3 and use BISE.
Comment: To be more specific, you can write all your dialogues/scripts in a text file and execute them on the fly, that's when a scripting engine is needed. Suspending is also needed because you may need to wait for user's input when executing the scripts. The BISE engine contains a very basic text adventure example which you may want to check.
Comment: I wouldn't integrate a scripting engine just for a dialogue system unless I were doing something very complicated. All that's really needed here is some text files and some work to read/display them.


A question about arithmetic progressions, a.k.a.  arithmetic sequences

Question: What is the relation between the general formula of the sum of $n$ terms of an arithmetic progression, $a n^2+b n+c$, and the first term $a+b+c$ and the common difference?
Comment: @mixedmath I think he means the formula for the sum of the arithmetic progression, not the formula for the arithmetic progression
Comment: @ThomasAndrews: That makes more sense. I'll delete my answer.
Answer: Suppose that the terms we are adding up are $a_1,a_2,a_3$, and so on. Let $s_1=a_1$, $s_2=a_1+a_2$, $s_3=a_1+a_2+a_3$, and so on.
If $a_1,a_2,a_3,\dots$ is an arithmetic sequence, let $d$ be the common difference. So $a_1=a_1$, $a_2=a_1+d$, $a_3=a_1+2d$, and so on. We therefore have $a_k=a_1+(k-1)d$. It follows that
$$s_n=a_1+(a_1+d)+ (a_1+2d)+\cdots +(a_1+(n-1)d).$$
The above sum is equal to
$$na_1+d(1+2+\cdots +(n-1)).$$
By a standard result, $1+2+\cdots+(n-1)=\frac{1}{2}n(n-1)$.  Thus
$$s_n=na_1+\frac{1}{2}(n)(n-1)d=\frac{d}{2}n^2 +\left(a_1-\frac{d}{2}\right)n.$$
Comparing with the proposed formula $s_n=an^2+bn+c$, we get that $c=0$ and $d=2a$.
Conversely, suppose that $c=0$, and the sum of the first $n$ terms is given by the formula $s_n=an^2+bn$.  The $k$-th term $a_k$ is then $(ak^2+bk)-(a(k-1)^2+b(k-1))$. This simplifies to $a_k=2ak +b$. Write $d$ instead of $2a$. Then
$a_k=kd+b=b-d+(k-1)d$, exactly the expression for the $k$-th term of an arithmetic sequence with first term $b-d$ and common difference $d$.
Another way: We are given that $s_n=an^2+bn+c$.  We will show that the sequence $a_1,a_2,a_3,\dots$ is an arithmetic sequence iff $c=0$, and will determine the common difference.
The first term (where we take first to mean $n=1$) is $a+b+c$.
So $a_1=a+b+c$.
The sum $s_2$ of the first $2$ terms is  $4a+2b+c$.  So $a_2$ must be $(4a+2b+c)-(a+b+c)$, that is, $3a+b$. Thus the difference $a_2-a_1$ between the second term and the first must be $(3a+b)-(a+b+c)$, which is $2a-c$.  This is the common difference, if the sequence really is an arithmetic sequence. Let's check whether it really is.
Let $k\ge 2$. We have $s_k=ak^2+bk+c$, and $s_{k-1}=a(k-1)^2+b(k-1)+c$.  Thus
$$a_k=s_k-s_{k-1}=(ak^2+bk+c)-(a(k-1)^2+b(k-1)+c)=2ak-a+b.$$
It follows that $a_{k+1}=2a(k+1)-a+b$.  The difference between $a_{k+1}-a_k$ between the $(k+1)$-th term and the $k$-th term is therefore $2a$ when $k \ge 2$.
We saw that the difference $a_2-a_1$ is $2a-c$, and that all further differences are $2a$.  We therefore have an arithmetic progression iff $c=0$. Then the common difference is $2a$.
Remark: If we are willing to take it on faith that the expression $an^2+bn+c$ does give the sum of an arithmetic sequence, say with first term $w$ and common difference $d$, then we can operate more concretely. Perhaps the following is intended.
We have $a+b+c=w$, $4a+2b+c=w+(w+d)=2w+d$, and $9a+3b+c=w+(w+d)+(w+2d)=3w+3d$.
Use the first two equations to eliminate $c$, also the last two equations. We get $3a+b=w+d$ and $5a+b=w+2d$. Subtract to eliminate $b$. We get $2a=d$. From $3a+b=w+d$ we then get $w=3a-2a+b=a+b$. Then from $a+b+c=w$ we get $c=0$.
Answer: If the sum of $n$ terms of an arithmetic sequence is
$$
s(n)=\color{#C00000}{an^2+bn+c}\tag{1}
$$
then $c$ is the sum of $0$ terms; that is,
$$
c=s(0)=0\tag{2}
$$
The general term of the arithmetic sequence would be
$$
\begin{align}
a(n)
&=s(n)-s(n-1)\\
&=(b-a)+(2a)n\tag{3}
\end{align}
$$
The first term of the arithmetic sequence would be
$$
a(1)=\color{#C00000}{a+b}\tag{4}
$$
Thus, the common difference of the arithmetic sequence is
$$
\begin{align}
a(n)-a(n-1)
&=((b-a)+(2a)n)-((b-a)+(2a)(n-1))\\
&=\color{#C00000}{2a}\tag{5}
\end{align}
$$
As for a relation among $(1)$, $(4)$, and $(5)$, we get
$$
\color{#C00000}{an^2+bn+c}=n(\color{#C00000}{a+b})+\frac{n^2-n}{2}\color{#C00000}{2a}\tag{6}
$$


What factors are used to generate Genius Playlists in iTunes?

Question: I'm curious as to all the factors that are taken into account when iTunes constructs a Genius Playlist. Do listening habits such as Play Count and Skipped Count have any effect? Are the ratings that I have assigned to my songs considered at all?
Answer: Itunes looks at your ID3 tags, if they match up with what other users have uploaded than Itunes makes a prediction. As more and more libraries are uploaded the predictions get better and better.
However this is not always the case, as songs that have been uploaded by a CD are still able to get "matched" Some speculate that it works by just the tempo of music that is matched with similar artists and genres.
Either way songs that are recognized are liked to a wealth of music.


Why does NO have a residence time of 4 days?

Question: If $\ce{NO}$ is unstable, why does it have an atmospheric lifetime of 4 days? I know that it has a lone pair and one unpaired electron making it highly reactive. Therefore, shouldn't it react immediately in the atmosphere?
Comment: Before you ask "why", ask "if".
Comment: Four days seems long, and there are other variables involved, mainly ozone concentration as NO + O3 is a major sink process for NO. Could you give a source for your stated value? Thx.
Answer: It could be possible that you're thinking of the overall lifetime of $\ce{NO_x}$ ($\ce{NO2 + NO}$), which indeed does have a longer atmospheric lifetime than $\ce{NO}$ individually and which even, at around 5 km altitude, has a lifetime of ~4 days. The two interconvert during the day due to photo-chemistry, and the ratio of the two is dependent on the photolysis rate of $\ce{NO2}$ ($j_{\ce{NO2}}$) and on the rate coefficient of the reaction between $\ce{NO}$ and $\ce{O3}$.
As $j_{\ce{NO2}}$ is constant with altitude, the ratio between $\ce{NO}$ and $\ce{NO2}$ is dependent upon the reaction rate coefficient between $\ce{NO}$ and $\ce{O3}$. This, in turn, is governed by the temperature, and under lower temperatures, the reaction rate is slower. Combined with a decrease in the number concentration of ozone (due to the decrease in the number concentration of air with increasing altitude, if we assume a constant mixing ratio of ozone throughout the troposphere, of course), the ratio favours $\ce{NO}$ over $\ce{NO2}$.
At higher altitudes, then, you do see a situation where there is more $\ce{NO}$ than $\ce{NO2}$, and where the overall lifetime of $\ce{NO_x}$ can be higher than the 1 to 2 days found at the surface (reaching, sometimes, almost 12 days in the upper troposphere).


Was Lord Hanuman born in Sumeru? Where is that place? Is it renamed recently?

Question: Where is Sumeru? I have been reading about Hindu Cosmology of seven continents and in that I came across Mount Sumeru. Where is it? Is it the birth place of Hanuman?
Comment: Yeah I think Hanuman birth details is lacking but I saw in Jai Hanuman suntv show about Hanuman in sumeru. Soon I will link the address of where I read.
Comment: Can you please tell where you read birthplace of Hanuman is Sumeru? Currently, your question asks two different questions i.e., asking birthplace of Hanuman and where is Sumeru and an additional question renaming it recently. Please limit this question to a single question. It is to avoid partial answers which may not satisfy the queries in a single answer.  Split these distinct questions into new questions.
Comment: You should ask only question per post. There are many questions in the post. Use @Username to reply.
Comment: Well I'll make it clear. This question is about Sumeru alone and when I read about it, the thing struck my mind was Jai hanuman where they showed Hanuman in Sumeru. That's why I asked whether Sumeru was birth place of Hanuman. @Sarvabhouma
Answer: Though the Valmiki Ramayan proper does not mention the exact place of Hanuman's birth, Uttar Ramayan does say it  to be Sumeru. However, local legend makes it to be Anjaneri near Nashik in Maharashtra and there is another contender for his birthplace at Hampi known as Anjaneyadri Hill.
In the Sundar Kand of Valmiki Ramayan Hanuman introduces himself to Sita as below:

कौरजो नाम वैदेहि गिरीणाम् उत्तमो गिरिः |
ततो गच्छति गो कर्णम् पर्वतम् केसरी हरिः || 5-35-80

"O Seetha! There is a mountain called Malyavan, which is the best among mountains. From there, a monkey called Kesari went to another mountain called Gokarna."

तस्य अहम् हरिणः क्षेत्रे जातो वातेन मैथिलि |
हनूमान् इति विख्यातो लोके स्वेन एव कर्मणा || 5-35-82

O Seetha! I am born in the womb of the wife of that Kesari the monkey, by the grace of the wind-god. By my activity alone, I am renowned as Hanuman in this world.

Since Kesari had moved to Gokarna before his marriage to Anjana it makes sense to assume that Hanuman was also born around that area rather than Meru. Hanuman also spent his whole life around Rishyamukh Parvat in Kishkindha which falls in modern day Karnataka, and is never mentioned to have gone anywhere near Meru ever again so it seems likely that he would have been born somewhere in the Deccan.
Nevertheless, since you have asked about the location of Meru or Sumeru, this is how the Vishnu Puran describes the geography of the earth:

Jambu-dwípa is in the centre of all these: and in the centre of this continent is the golden mountain Meru. The height of Meru is eighty-four thousand Yojanas; and its depth below the surface of the earth is sixteen thousand. Its diameter at the summit is thirty-two thousand Yojanas; and at its base, sixteen thousand: so that this mountain is like the seed-cup of the lotus of the earth.
The boundary mountains (of the earth) are Himaván, Hemakút́a, and Nishadha, which lie SOUTH of Meru; and Níla, Śweta, and Śringí, which are situated to the NORTH of it.

The Varshas or countries between these ranges are Bhárata, south of the Himaván mountains; next Kimpurusha, north of the latter, and south of Nishadha, is Harivarsha; north of Meru is Ramyaka, extending from the Níla to the Śweta mountains; Hirańmaya lies between the Śweta and Śringí ranges; and Uttarakuru is beyond the latter, following the same direction as Bhárata. Each of these is nine thousand Yojanas in extent.
Ilávrita is of similar dimensions, but in the centre of it is the golden mountain Meru, and the country extends nine thousand Yojanas in each direction from the four sides of the mountain. There are four mountains in this Varsha, formed as buttresses to Meru, each ten thousand Yojanas in elevation: that on the east is called Mandara; that on the south, Gandhamádana; that on the west, Vipula; and that on the north, Supárśwa.
The country of Bhadráśwa lies on the east of Meru, and Ketumála on the west; and between these two is the region of Ilávrita.

Please note BhArat is mentioned as Nabhi Varsha in the image above because that was its early name. As you can see, according to the Puranic geography, Meru exists bang in the middle of the earth in the center of the Ilavrita Varsha while Hanuman lived in Bharat Varsha which is south of the Himalayas.
Comment: Can you entertain the possibility that yours & other's logic may not always match? That is the precise reason there are options for multiple answers and also the provision for selecting the perfect answer as per the OP. Criticizing other's answer is in quite bad taste especially when you yourself have given an alternative answer that would cover all that you had to say :) Also, I don't believe anyone can call any answer based on the scriptures a mistake just because of their own opinion on the topic. Hinduism has thrived on multiple views and that is how this site should also be.
Comment: Well the Uttara Kanda is not really a part of the original Valmiki Ramayan but thanks will add the suggestion.
Comment: @YDS am sure we all understand the difference between clarification and calling other's answers illogical. Such comments that are routinely made by many here are really uncalled for and unnecessarily vitiate the atmosphere on this site. You can share what you think is the right answer but should not criticize others for their attempts to answer!
Comment: "Though the Valmiki Ramayan does not mention the exact place of Hanuman's birth" - actually Uttar Kanda provide details on it...pls mention that Kishkinda Kand of Valmiki Ramayan does not mention it or remove/corect this...
Comment: The very source from where you gave kishkinda kand reference says Balakand also not part of Valmiki Ramayan same as Uttarakand...but this source itself mention balakand...if we remove Bala and Uttar kanda then most of the Qs will be unanswered from Ramayan...and Uttar kand is mentioned in Pauranik retailing of Ramayan too...saying it's not part of Ramayan is doubtful...
Comment: Yes Bala Kand may also be considered interpolated but the source is Sundarkand here so I don't understand why you are debating it. If you want to make a point based on my source you may kindly notice he doesn't even mention Uttar Kand anywhere showing where it stands next to the other portions! Anyhow the debate is meaningless since I added the sentence about Uttar Kand in the answer.
Comment: "seems logical that he would have been born somewhere in the Deccan rather than at Meru mountain"..No it's not logical.. specially when some text says that they were migrated to Kishkindha from Meru...
Comment: Since your answer is selected already I don't understand why you are still commenting. Strongly advise people on this forum to drop their egos while answering questions or having discussions. The focus here is to learn not compete!
Comment: There is nothing like competing...goal is to know what's right and not who is right...there is no ego also...but to know/learn better one should ask clarification and I did that...I don't think asking clarification is wrong...and why my answer got selected or deleted or downvoted or upvoted affects this??
Comment: Okay..so one should not comment if he finds answer illogical or sees some translation issue..?...IMHO, ego is in those people who don't want to correct their post and not in those who point that mistake..:)...I hv seen highly upvoted posts which were deleted/edited after mistakes pointed out by others..I think that's the one way of improving quality here..but there are many posts which were not edited even after mistakes pointed by many users including moderators..bdw nothing personal or competition with u.. :)
Answer: Was Lord Hanuman born in Sumeru? Is it the birth place of Hanuman?
Yes, as per UTTARA KANDA of Valmiki Ramayan:

[The ascetic Agastya said to Lord Shri Rama:] I am not capable of describing to thee the wondrous childish feat which Hanuman did perform in his boyhood. But if thou art, O Raghava, greatly anxious to hear it, I shall relate do thou hear with a quiescent mind.
Hanuman's father Kesari reigned in the mountain Sumeru which resembles gold by the inluence of the sun. Kesari had a well known wife by the name of Anjana to whom he was greatly attached. The deity Wind begot on Anjana an excellent son. Repairing to a dense forest for collecting fruits, the excellent damsel gave birth to Hanuman.

Earlier, Riksharaja too used to live on mountain Meru and gave birth to Vali and Sigriva. Later,

Beholding his son Riksharaja with his sons(Vali and Sigriva), Brahma, the grand father of the Devas, consoled him in diverse ways. Then he ordered the celestial messenger saying "At my behest, O emissary, do thou proceed to the highly picturesque city of Kishkindha. That golden, big and charming city is worthy of Riksharaja. Do thou place there Riksharaja, the foremost of Vanaras, with his sons; and having invited the leading Vanaras and others and received them courteously do thou install him on the throne. On beholding this Vanara chief, gifted with intelligence they shall be all subject to him."
Brahma, having said this, the celestial emissary, with Riksharaja before him, proceeded to the highly picturesque city of Kishkindha. And having entered there with the velocity of the wind, he, at the com mand of the Patriarch, crowned the leading Vanara Riksharaja as king. All the Vanara, residing on earth consisting of seven insular continentsand bounded by ocean, came under his subjection.

So, Hanuman, Sugriv and Vali were born on mountain Sumeru but later migrated to Kishkindha.

Where is Sumeru?
As per Śrīmad-Bhāgavatam (Bhāgavata Purāṇa) 5.26,

The planetary system known as Bhū-maṇḍala resembles a lotus flower, and its seven islands resemble the whorl of that flower. The length and breadth of the island known as Jambūdvīpa, which is situated in the middle of the whorl. In Jambūdvīpa there are nine divisions of land. Amidst these divisions, or varṣas, is the varṣa named Ilāvṛta, which is situated in the middle of the whorl of the lotus. Within Ilāvṛta-varṣa is Sumeru Mountain.

More details can be found in this article and in this answer.
Comment: @AkshayKumarS updated the answer...
Comment: Yeah where is it? Mount Sumeru seems to have connection with Hindu Cosmology of 7 contients from Jambu Dvipa https://www.bhagavadgitausa.com/HINDU%20VIEW%20OF%20THE%20PHYSICAL%20WORLD.htm
Answer: Mt. Semeru is located in Indonesia.(https://en.wikipedia.org/wiki/Semeru) India and Indonesia have a lot of common culture. And Indonesia was like an extension of Indian kingdoms before the Dutch colonized Indonesia and British colonized India. Hinduism was the primary religion in Indonesia before Islam became dominant.
Comment: Hi, Welcome to Hinduism Stack Exchange. [Please visit Guidelines for new user for answering questions.](https://hinduism.meta.stackexchange.com/questions/125/guidelines-for-new-users-answering-questions)


AFWALL+ doesn't block apps when on WiFi

Question: I'm currently running AfWall+ on LineageOS (Android 7.1.2) and seem to have a problem with this app. When I'm on WiFi it doesn't stop anything it's supposed to (works just fine on mobile).
Can someone please advice what cold be the problem?
Answer: I came across your question because I had the same problem, and I just figured it out (although it might be a different cause in your case).
Details of my case (to see if it applies):
I'm also on 7.1.2 (LineageOS 14.1), and I'm using a VPN with AFWall+ v2.9.8. AFWall+ is supposed to only allow connections through the VPN. It's actually been working fine for a while, but it suddenly started allowing connections through my WiFi even when the VPN was off (it still worked properly on mobile data).
I eventually came to the conclusion that this was caused by the fact that my ISP provider started switching to IPv6, and it seems that AFWall+ doesn't support IPv6 by default (by that, I mean it doesn't apply the rules to IPv6 traffic). This is, of course, a wild guess, because I couldn't find any manual for it that explains the details of the slightly cryptic/confusing settings (e.g., not sure what the "Only Control IPv6 Chains" option means and why it is mutually exclusive with the "IPv6 support option).
Solution:
Having said all that, the solution that worked for me was to go to Preferences > Rules/Connectivity and under "IPv6 Chains", check the option for IPv6 support ("Enable support for IPv6").
When I applied the firewall rules after doing this, it applied twice as many rules as it was before I enabled IPv6 support. This is what led me to believe that previously, it was only applying my rules to IPv4 traffic, while now, it's applying my rules to IPv4 and IPv6 traffic (hence, twice as many rules).
Of course, even if I'm unclear on the AFWall+ settings, the main reason I believe this is the cause/solution is that everything works as expected now!

AFWALL+ doesn't block apps when on WiFi


ubuntu uses old kernel instead of new one

Question: The command uname -r gives 3.5.0-17-generic, but when I checked in synaptics the kernel 3.5.0-43 is installed, but it seems the system uses the old kernel instead.
How can I make it use the new kernel?
Answer: Have you restarted since installing the new kernel? A kernel cannot be fully updated until the computer is restarted. If this does not work, try reinstalling 3.5.0-43. You should also try Software Updater to get new versions as none of those are the newest version.
Comment: Reinstalled and it was solved.


What is the name for the opening in the mouth for the nasal passages?

Question: Is there a proper anatomical name for the opening in the soft palette where the nasal passages enter the mouth?
Comment: Something other than oropharynx?
Comment: @skymningen From looking at drawings it looks like I'm talking about where the nasopharynx meets the oropharynx. There may not be a specific name for it. Sometimes openings have their own separate name (like the foramen magnum, or the anus, etc) but not always.
Answer: From what I understand from your comment is that you are asking for opening which connects the nasopharynx to oropharynx.
This opening is is connecting two parts of pharynx , acting like a bridge therefore it was named as Pharyngeal/Nasopharyngeal isthmus.
According to this site:

isthmus of pharynx
Type:Term
Definitions
  1. passage posterior to the soft palate by which the nasopharynx and oropharynx communicate (i.e., the junction of nasopharynx and oropharynx), closed during swallowing by elevation of the soft palate and contraction of the posterior fascicle of palatopharyngeus (muscle), forming a Passavant cushion.
Synonyms
  isthmus pharyngis , pharyngeal isthmus

Source of image: Textbook of Anatomy: Head, Neck, and Brain : Vishram Singh


Ohm's Law and transmission of electricity

Question: Electricity is transmitted at high voltages. It is said that this reduces current and consequently resistance. But according to ohms law, low current must face high resistance. How is this contradiction possible?
Answer: Resistivity is a property of materials, and thus, resistance is a property of the material too, at least for most practical purposes. So $R$ is a fixed value for a certain device. In particular, for the wires that transport electricity.
Since Ohm's law holds:
$$V=I\cdot R$$
If you apply more voltage, you will have more current. As in any other wire.

This must not be confused with the transformers. Transformers apply conservation of power (with relatively high efficiency), and power is $P=V\cdot I$.
$$ V_1\cdot I_1 = V_2 \cdot I_2$$
Energy is generated in power plants. The power plants supply a fixed value $P_1=V_1\cdot I_1$. You can only control the exit. $V_2\cdot I_2=constant$. If you want more voltage, you'll have decreased current, and vice-versa.
Those ifnal values $V_2, I_2$ are then transmitted to wires.
Comment: @MohammadNoorAlam, not every load on the power grid is a resistor.
Comment: how can low current face low resistance, which is not possible by ohms law
Comment: Indeed. The wires are usually driver from transformer to transformer. If you only look at the wire, you're not seeing the entire circuit.
Answer: Not every load on the power grid is a resistor. So not every load obeys Ohm's Law.
In particular, the load on a high-voltage circuit in the power grid is likely to be a transformer.

(image source)
Here, the left side of the transformer is called the primary side, and the right side is called the secondary side. Two main parameters of the transformer design are the number of turns of wire around the primary side of the core, $N_P$, and around the secondary side, $N_S$.
The (ideal) transformer is governed by the rules
$$ V_S = \frac{N_S}{N_P}V_P$$
and
$$ I_P = \frac{N_S}{N_P}I_S.$$
Notice that this means that $V_P I_P = V_S I_S$, so that the power delivered to the load on the secondary is equal to the power delivered by the generator to the primary of the transformer.
Using a transformer, a low-resistance load (like dozens or hundreds of light bulbs connected in parallel) can be transformed to appear to the generator as a much higher resistance. Thus power is delivered with much lower currents in the primary circuit than in the secondary circuit, and resistive losses in the primary circuit are reduced.
Answer:
It is said that this reduces current and consequently resistance.

This is wrong. The resistance of the cable does not depend on the current through it (at least not so much that it would matter here).
The reduced current leads to reduced dissipated power in the wire.


Is it a good idea to add tags for engines with low popularity?

Question: Whilst it would make people more aware of the game engine, would it really be of much use to do this? It could be considered as extra clutter, for example, if I added a tag referring to an engine that only I knew about, would anyone really care, let alone know the answer to any questions on that tag?
Answer: Tags are about categorization of on-topic subject domains for searching and filtering. They are not about advertising or otherwise "making people aware" of products, and so should not be added for that purpose.
If an individual question is really about some engine (and isn't just a more general problem that happens to be done with or in that engine), it's certainly appropriate to add the tag to that one question. Unless the engine in question is a private, proprietary product, which case it's pointless.
It would not be appropriate to go back through the question history and retroactively apply that tag to anything that looks remotely relevant.
Comment: When I add a tag that does not exist, I generally tag another question, just to make it so that there is not only one question with that tag, to prevent the tag from being removed by the system.
Comment: That's fair, in general, although I'm not personally convinced the engine-specific tags are really that great and need proliferation.
Comment: Yeah, if the questions are generic and not specific to the engine, in theory, there is not need to tag them. Same with the language tags, but we're kind of stuck with it.


What's the smallest wifi connector for the Raspberry Pi Zero?

Question: I'm looking for a small and neat solution to give the Pi Zero Wi-Fi connectivity. Something along the lines of a Micro-B USB dongle would be nice, but I'm not sure they exist. I'm currently using an OTG adapter plus standard type A dongle and the amount of superfluous wire and plastic involved is ridiculous.
Comment: Why not [soldering the wifi chip directly to the board](http://hackaday.com/2015/11/28/first-raspberry-pi-zero-hack-piggy-back-wifi/)?
Comment: I really hope someone near the RPi Foundation reads RPi.SE and absorbs the demand for the Pi Zero+ with on board WiFi!
Comment: @Ghanima I doubt they will take any notice.  Neither do I think they should.  People wanted a lite version of Jessie.  Now people don't like the lite version and want features added back.  Similarly people have argued for an unpopulated Pi.  Now they have an unpopulated Pi they want features added.
Comment: While the hack certainly has its merrits, I still argue that a Pi with WiFi would be something with many use cases. And @joan, there was never a Pi with WiFi yet, so I don't want anything back ;) I still think that a WiFi'd Pi fits the goals of the Foundation well.
Comment: @Ghanima, they really should, it would huge improvement on several fronts to have this built in. User236012, thank you that's certainly an interesting approach!
Comment: @joan :-) came here looking for info on how to get my 5 OG zeros up to date date with my only zero W - as Ws are so hard to get hold of currently - and couldn't help but chuckle at your comment.  Hope you're having a great day.
Answer: You can do better than that micro USB adapter. Try this guy out: http://www.amazon.com/dp/B015XA3W0G/. I'm still waiting for my Pi Zero to show up, but I was able to test that adapter with another couple of devices: https://twitter.com/techhat/status/674249853174546432.
Comment: link to coffee maker?
Answer: I have not seen any dedicated micro-USB Wifi Adapters, but you can come pretty close by buying these two products:

A microUSB-to-USB adapter - there is also this one but it might not have data connections as it is intended for charging.

A micro-sized WiFi adapter like the Kootek or the Edimax (both have the same hardware underneath and work with Raspberry Pi's).

Plug 2 into 1, then 1 into the RPi and you have Wifi in a smaller size than your usual USB Wifi dongle (excluding the Kootek/Edimax of course).
Comment: That's pretty much my current setup I wish to improve upon, albeit mine has a few cm of cable between each end of the adapter. Even without the cable the whole thing seems several times larger than it could be, and is quite incongruous coming out at right angles from the run of the board. I have since found this: http://www.everbuying.net/product1101392.html which should improve matters substantially, but a micro socket based dongle could be half this size again I'd have thought.
Answer: Problem Solved!!!
Just get an IoT HAT for Raspberry Pi from RedBear and for only $9, you get WiFi as well as Blue Tooth. IoT HAT for Raspberry Pi

This really is a must have for Pi Zero
Wi-Fi and Bluetooth are essential for most projects and Pi Zero is just too small to have a bunch of wires and gizmos connected to it.
Best of all, a HAT which is the perfect size and exact match to the Pi Zero provides the best possible form factor. Nothing that sticks out like a sore thumb. Nothing that makes the final package more bulky than it needs to be.
You can even use the standard acrlyc protective case after installing the IoT HAT.
Last but not least, you can order an optional extended range WiFi antenna from RedBear
I have to say, I am really impressed by these guys! They get it!
And I am impressed not just by this project, but by other Kickstarter projects RedBear has launched.
Comment: Internet of Hats Hat is what I put on when I become an Internet of Developers Thing.
Comment: how can I buy one?
Answer: The best option is HubPiWi - an add on board for Raspberry Pi Zero with 3 USB Ports and an integrated Wifi. The board has a PCB Antenna and does not require and Cable or Connector.

There are two versions of it - one for newer Pi Zero 1.3 ( with  Camera Connector) and one for earlier versions. The details can be checked at
HubPiWi at kickstarter
Answer: Took me some searching, but then I found this:

https://www.modmypi.com/raspberry-pi/raspberry-pi-zero-board/rpi-zero-accessories/pi-zero-wifi-micro-usb-wifi-dongle
I think this would be the smallest plug and play option.
Answer: For the adapter, you can also try the following product:
Micro USB OTG Adapter
http://www.amazon.com/Adapter-LDesign%C2%AE-Android-Smartphone-Samsung/dp/B015XA3W0G/ref=sr_1_2?s=pc&ie=UTF8&qid=1464898004&sr=1-2&keywords=micro+usb+wifi+adapter
Comment: Instead of literally doubling the cost of the Pi Zero why not get 5 connectors for $2.34 http://www.amazon.com/gp/product/B015GZOHKW/ref=s9_simh_gw_g147_i2_r?ie=UTF8&fpl=fresh&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=&pf_rd_r=198SJWZHS53RGK0DV3JR&pf_rd_t=36701&pf_rd_p=b2f7ca14-9d6b-4341-8eb1-a70e22819d56&pf_rd_i=desktop
Comment: That's actually the exact same product from techhat's answer
Comment: @JeffMeden Yes, you are right, it's the same product, but my answer has images ;)
Answer: Well, time passed. I think the cheapest option now is to buy the Raspberry Pi Zero W which has Wifi & Bluetooth built-in.
https://www.adafruit.com/product/3400


Profile2 with Display Suite

Question: I am using profile2. In main profile type I have created some fields. Now according to my project need I want to use display suit for manage display. I followed instruction according to link, but no effect. If I do some changes in manage field it is showing but if I do any changes in manage display it is not effecting.For example in my first screen shot designation is above full name that i have set by manage display but in front end full name is above

Please help me if some one sort out this issue.
Thanks in advance
Answer: A nice way to deal with that is to temporarily get out of profile2 rendering way. What I explain here works also for the input form.
1 - Enable the field_collection module.
2 - Create your fields collections.
3 - Then you can arrange the field collection display, including for the form.
4 - You replace your fields in profile 2 with the field collections.
5 - Enable the overlay module (not mandatory), at the bottom of each field collection you can now see add and edit buttons.
Now your fields collections are rendered as you wanted, including for profile2 form.
This is a "good to go" workaround as can be seen on the screenshot.

OR
profile2-display-suite-forms
Comment: Same thing we can do with content type. Then why not with profile2.

Profile2 with Display Suite


How should I properly ground a separate building?

Question: I installed a sub panel in a building that is around 200' from the main panel so I omitted the neutral and ground from the main panel therefore running only the 240V from the main. I hammered a new ground rod and bonded the ground and neutral at the new building sub panel, which I figured would give me the same setup as a main panel, but when I turn on one of the single pole breakers at the sub panel voltage dropped from 125V to around 23V. I ran three way wire to the building so I hooked up the neutral at the main to the sub panel and everything works fine so I know there are no breaks in either power line. I'm wondering what I need to do to
Comment: Are you asking why there's a voltage drop, how to fix the ground rods, or whether you can bond the ground and neutral at a sub panel?
Comment: I also do not understand the question.  So far I read "I did something different to my sub than what was done at the main and it behaved differently."
Comment: You're missing part of that last sentence: "_what I need to do to_" ... something
Answer: Congratulations, you've created an open (floating) neutral.

"I omitted the neutral and ground from the main panel... I hammered a new ground rod and bonded the ground and neutral at the new building sub panel, which I figured would give me the same setup as a main panel..."

This is partially incorrect. The main panel should be supplied from the utility with two ungrounded (hot) conductors, and one grounded (neutral) conductor.  You'll then have an on-site grounding electrode (ground rod, etc.), which the equipment grounding conductor and grounded (neutral) conductors will be bonded to.
To feed your subpanel you'll have to provide at least two ungrounded (hot) conductors, and a grounded (neutral) conductor from the main panel.  Since this is a separate building, you are correct that a separate grounding electrode is required. However, you'll want to make sure it is an adequate ground before using it.  It's not likely you'll have the equipment to do this, so you'll probably have to call somebody in to verify a good ground.
If there are no other bonded metallic paths between the buildings (water pipe, gas pipe, coaxial cable, etc.) then you're allowed to simply run two ungrounded (hot) conductors and one grounded (neutral) conductor.  In this situation, the grounded (neutral) conductor should be bonded to the grounding electrode at the subpanel.
If there are other bonded metallic paths between the buildings then you should run two ungrounded (hot), one grounded (neutral), and one grounding conductor. In this case, the grounded (neutral) conductor will not be bonded to the grounding electrode at the subpanel.
See: National Electrical Code 2011 250.32(B)(1)
Answer: You should run a neutral and a ground between the panels. Your electric utility provides the neutral, not the earth, so skipping the neutral is wrong. And the ground is required to provide fault safely for the run from the main to the sub panel, so skipping that is wrong, too.
Additionally grounding the sub panel is required since it's a separate building.


Is 2005 bottle wheat beer ok to drink?

Question: Found a box of home brewed beer in an old cellar marked 2005. Bottles look ok and caps are good. Would it be safe to drink?
Comment: Please drink one and post back here with a comment telling us how it tastes! While it won't hurt you, I suspect it might taste stale, or like wet cardboard from oxidation. Or, it might be delicious!
Comment: Get it cold, then taste it. Take a giant gulp, don't be afraid! But dont forget to put your video cam on a tripod sop we can see your face on youtube, good or bad! :)
Answer: It will be safe to drink - beer doesn't go bad in a way that can cause illness. If it will taste good or not is another thing altogether!
Answer: I don't see why it wont be ok to drink. There is nothing wrong with opening one and trying a little bit to see how it tastes.
If it tastes all good then put the rest in the fridge and enjoy.
Comment: Higher gravity and bottle conditioning will go a long way toward preserving cellar stored beers. Hops may subside a bit but otherwise, should be good unless stored at higher temps.
Answer: Try one and pour it in a glass gently to see if there is year sediment.  If there is some, that means that the beer was bottle conditioned (good sign) but still try to keep the sediment out of the glass as much as possible.
There are some wheat beers that get better with age if this is a Belgian or select German style!

Is 2005 bottle wheat beer ok to drink?


What is LED spatial distribution?

Question: I was going through a 5mm blue LED data sheet and found this diagram in it. Couldn't figure out what it is.
Answer: It is a plot of the amount of light for each direction. Imagine the LED is in the bottom middle, where the 0 is and it is shining up.
Close to the LED, the beam is around 40 degrees wide (20 degrees to each side)
If you let the LED shine flat over a piece of white paper, the marked area would be the brightest.
Comment: I'd say more like 60 degrees but that is probably not worth saying!
Comment: True, I just wasn't as close to the LED as you were ;-)
Answer: This is a plot of the relative output over the angle of view.
'relative' because you can see the angle it shines brightest is marked "1.0" so all the other values are scaled from there.
Imagine if you had the LED from the datasheet and a photosensor, and you moved the photo sensor around the edge of a protractor with the LED at the center of the protractor's base. As you move the photosensor around the angles from -90 (from the side) to 0 (pointed straight at each other) to 90 (from the other side) the output of the photosensor would draw out this plot.
The main takeaway from this is most of the light is contained in a 20 degree arc straight ahead, and ALL of the light is contained in a 60 degree arc (the plot goes to zero around the 30 degree mark). Almost none of the light is being projected in the angles from 40 to 90.

What is LED spatial distribution?


Asking for a raise when you are quitting for future job search

Question: I'm going to continue my higher education and about to leave my current jobs.
I've already told my manager that I'm going to leave but I've not handed in my official notice yet. Is it a good idea to asking for a raise before quitting to improve negotiability in the future job search.
Comment: No it's not a good idea, because you're implying that you will divulge your current earnings to your potential employers., which is a terrible idea, unless you like limiting any future offer to your last one.
Answer: If you've already put in your resignation, there's no point in asking for a raise. Your employer has absolutely zero reason to give it to you, and it will only make you look bad. I cannot imagine a scenario in which you'd be successful.
As to your worry about being able to negotiate your future salary, your past salaries should not affect how much you ask for in the future. Negotiate based on the market and what you think you deserve, not what you have been paid in the past. In some places it's even illegal for interviewing companies to ask for your previous salary. Besides, if you are going back to school, your value should be increasing after you've received more education, so your current salary should not matter.
If you want to know how much salary you should be asking for in the future, I recommend taking a look at this other question: How can I determine a reasonable salary to ask for?
Comment: I agree it's not the best idea to do that when leaving the job but - `Negotiate based on the market and what you think you deserve` - wouldn't knowledge of how much he could possibly be earning at the current job be some kind of a indicator of current market state?
Comment: @aMJay Yes, that is one indicator, but it's not always reliable. If you are underpaid at your first job and then use that wage as an indicator for your next job, and so on, you will be underpaid for the rest of your life. Check out this other question for some great advice on how to determine a reasonable salary: [How can I determine a reasonable salary to ask for?](https://workplace.stackexchange.com/questions/896/how-can-i-determine-a-reasonable-salary-to-ask-for)
Comment: @aMJay Particularly in OP's case, where they are leaving to further their education, their next job could easily be in a completely different industry (or a part time job to help out while in school), making it even less relevant.
Answer: You'd just about kill any chance for getting a good reference.
Doing so would be considered the nadir of unprofessional behavior.  Some companies take it very personally when you leave.  I know one company where, if you leave, you may never be rehired.
So, if they are already a bit unhappy that you are leaving, and then compound it by asking for a raise on your way out the door, it's highly likely that they would consider it a slap in the face.
Look at it from the employer's point of view.  You just cost them money by announcing that you are leaving.  You're going to add insult to injury by asking to cost them more money without any benefit to them.  How well do you think this would be received?
Comment: The last paragraph says it all!
Answer: Yes, you can, and I recommend you do. But you're unlikely to get the raise - because the company gains nothing by it.
If you were to say "i'm going to company X unless you give me a raise" that's fine, it makes sense. But unless you can believably say "i'm going to university Y unless you give me a raise" then why would the company give you a raise?
In this case, you've already told your boss you're going... so they don't really have an incentive to give you more money.
I haven't had the same experience as Don - heck, I've gone to study and come back to the company I left from, I don't see why a company wouldn't want to re-hire someone they already liked and is now provably more valuable.
But it's hard to make a real case for a pay rise, but I do suggest you try it to get used to asking for more money.
Comment: You say you recommend asking for the raise, but your entire answer explains why you think it won't work. The only thing you mention is getting practice asking. Can you explain more why you think the OP should ask for a raise before leaving?
Comment: @DavidK the only reason I suggest it is to get practice asking, as you note. It's always good to have done something before, even when the stakes are different/low/non-existant. I don't think asking will work unless the OP has some circumstance we're not aware of, yes. But I don't see why that precludes getting more experience in asking for a raise either. I don't, in short, see any repercussion from asking for a raise in this scenario.


Does ISO 50 reduce the signal level from CCD/CMOS?

Question: As I know, ISO (in digital photography) is simply a gain power of electronic amplification of an electric signal read from the sensor. Is it guaranteed that minimal ISO setting is just a "minimal amplification", but not a signal reduction? My question is can my camera at low ISO setting (50) actually reduce the actual CCD/CMOS signal? My camera is Sigma dp1x.
Comment: I have written an answer. However, It is incomplete because I cannot say anything about specific camera. If you photograph some even coloured gradient at both ISO50 and ISO100 in manual mode (same shutter and aperture) in RAW so that camera does not move and so that one border of gradient is blown white at ISO50 and share them I will be able to tell if camera reduces signal in ISO50 or if it is fake. Is my suggestion clear enough?
Answer: Sensors only have the one sensitivity, called native sensitivity, of how many photons were collected.
Higher ISO simply multiplies, to shift the histogram data up, brighter, but bringing low noise up with it.
Lower ISO 50 simply shifts the histogram down, dimmer, which lowers noise too, but also limiting the dynamic range, the top half of range is unused.  The visual histogram is adjusted accordingly (blank top half is not shown).  Nikon does not ever call it ISO 50 since range does not meet ISO specifications.  Nikon calls it LO 1 (1 EV down).
Comment: yup. always try to stick with native ISO or multiples of it
Answer: Since the specs of the DP1x I can find online list 100 as the lowest (and presumably base iso) setting, and 3200 as a boosted ISO level, my guess would be that the iso 50 setting isn't done by controlling gain across the sensor.  It is probably done in in-camera processing, as digital pull processing. That is, the image is actually shot at iso 100, but exposed for twice as long, and then the exposure is brought down in post.  This actually decreases the dynamic range, but can be useful if you need a 1-stop ND filter in the field and forgot to bring one with you.
I have a Canon 5DMkII, and the iso 50 setting on it is done in this way.