What is the point of a video call interview as opposed to a telephone interview?

Question: Why is it some employers want to do video calls, such as Skype, for interviews instead of just a phone call? The only reason I can think of is so they know how you look, but what difference does that make?
Answer: Lots of reasons. First, they want to make sure you aren't cheating on the questions by having someone else feeding you the answers or looking them up on Google.
They want to see your body language to assess your reactions to the questions beyond just your words.
There are some unethical people who do the phone interviews and then are not the people who show up when they get hired. So they want to see you to see if you are actually thhe person they hired when you get there. This is especially true if the hiring offical has been burned in the past by having a very knowldgeable phone interview result in a totally incompetent person showing up for work.
And depending on the job, appearance might be important as you might have customer contact and they want to ensure you are someone they would want to see as the face of the company.
Will some people be assessing you on irrelvant factors like race or weight? Yes. But those same type of people may be assessing you on other irrelvant factors on a phone call like your name or  your accent.
Comment: +1.  Part of seeing body language is also being able to see the non-verbal cues that say "I'm done with my answer" vs. "I'm pausing before I continue my answer".  A phone call between people that have no prior context often leads to either awkward pauses or people unintentionally interrupting each other.  That's less of a problem when there is video to go along with the audio.
Comment: This question is part of this week's [Broken Windows For Review](http://meta.workplace.stackexchange.com/questions/2960/broken-windows-for-review-week-4) on meta.
Comment: Also to add, it makes it easier to understand the interviewee especially when the language of the interview is not their first language.
Comment: Don't forget screen-sharing (which most video-calling programs will do).  Particularly for technical/coding interviews an interviewer may want to observe in realtime as you write code.
Comment: I think the interview is kind of like a first date. Would you want to date someone who you just phoned with? If you have a video conference you would feel more confident in what to expect dating that person. It's the same letting you in to the company as getting into a relationship. The suggestions here about cheating and whatnot are only marginally relevant like 1% important
Answer:
Why is it some employers want to do video calls, such as Skype, for
  interviews instead of just a phone call?

Body language.
You've probably noticed that you have more information conveyed to you when you talk to someone in person, rather than on the phone.
The look on their face, the tilt of their head, the shaking or nodding their head - these all indicate what the person is thinking as much as their words do.
This is what employers are trying to gain (at least to some extent) by using video rather than just phone calls.
Comment: Yes. In my experience, employers who use Skype for interviews are doing it because you're not local -- they would rather have an in-person interview, but this is the best they can do and it's way better than voice-only.  (In my recent job change, I had a Skype interview with the hiring manager first and then they flew me in to interview with the rest of the team.  I got the impression that's pretty common.)
Answer: Video calls give them a better look at you in a number of different ways. The audio quality is clearer than phones provide. They can check that you're able to dress properly and groom yourself. They can see your body language, and you can see theirs.
On the whole, video calls provide a much better experience and clearer communication between both parties. If both parties have computers with webcams and microphones, why wouldn't they want to use them for something as important as a job interview?
Comment: "The audio quality is clearer than phones provide" - doesn't match my experience with any video call I've ever been part of.


What is the best automatic chess playing app for a beginning level player?

Question: I play chess very infrequently. Whenever I restart, I take a bit of time to get up to speed. Which chess playing apps are best for a beginner? I would prefer apps that scale up in diifficulty according to a player's skill.
Comment: either I miserably humiliate the AI, or it humiliates me... I stopped trying to find a balanced AI years ago, now I play online chess
Answer: Shredder is an awesome Chess Program.  If you have an IPhone or Android Shredder is present and if you want for Computer along with Shredder you can use Fritz also.  I personally like both of them.
Answer: If you have a Microsoft Windows-based PC or laptop then there is no problem. They provide a very good chess game with different skill levels and appearances.
Comment: Thanks for the answer. I guess one needs to choose that at the time of install. My current installation doesn't appear to have it. Any other recommendations?
Answer: Back in the day, I found Chessmaster to be very beginner friendly, with a variety of AIs to choose from. It also had some instructional segments included, which were good at the time.
Now I lose against Stockfish whenever I'm looking for a good beating. I don't think it's very good for beginners, even if you constrain its skill quite a bit.
Answer: If you want to improve your skills, maybe gamezer.com is useful. It's not an app, but a website you can visit with an iphone, ipod, or whatever smartphone. It also provides skill  levels.


What is the potential to use for non-dispersion interactions?

Question: Although liquid argon's intermolecular potential can be described using a Lennard-Jones (LJ) potential, which takes into account dispersion forces (induced dipole-induced dipole interactions), what potential do you use when also including the effects of dipole-induced dipole and dipole-dipole interactions?
Comment: Related: http://chemistry.stackexchange.com/questions/27803/why-are-c6-dispersion-forces-named-c6
Answer: Because all three of these interactions are of the same order in the interelectronic distance ($1/r^{6}$), they are all captured within the Lennard-Jones potential to the extent of the accuracy of the potential. From the "Limits" section:
The term Van der Waals (vdW) forces roughly includes the following intermolecular forces:

the permanent dipole-permanent dipole force (Keesom force), which is an electrostatic term,
the permanent dipole-induced dipole force (Debye force), which is an induction or polarization term,
the induced dipole-induced dipole force (London dispersion force), which is the dispersion term.

the forms of which are
$$
\begin{align}
V_{\text{Keesom}} &= \frac{-m_{1}^{2}m_{2}^{2}}{24\pi^{2}\epsilon_{0}^{2}\epsilon_{r}^{2}k_{b}Tr^{6}} \\
V_{\text{Debye}} &= \frac{-m_{1}^{2}\alpha_{2}}{16\pi^{2}\epsilon_{0}^{2}\epsilon_{r}^{2}r^{6}} \\
V_{\text{LJ}} &= 4\epsilon \left[ \left( \frac{\sigma}{r} \right)^{12} - \left( \frac{\sigma}{r} \right)^{6} \right]
\end{align}
$$
Note that the LJ potential contains both a repulsive ($1/r^{12}$) and attractive ($-1/r^{6}$) component. This is not the form of the dispersion interaction, but is both a suitable mathematical form that encapsulates a few noncovalent (vdW) interactions together and is easy to evaluate on a computer.
You may also be interested in the form of a more complicated potential, such as the AMOEBA polarizable force field, which uses a slightly different form for the pairwise vdW interaction ($i,j$ are atoms)
$$
\begin{align}
U_{\text{vdw}}(ij) &= \epsilon_{ij} \left( \frac{1.07}{\rho_{ij} + 0.07} \right)^{7} \left( \frac{1.12}{\rho_{ij}^{7} + 0.12} - 2 \right) \\
\rho_{ij} &= \frac{R_{ij}}{R_{ij}^{0}} \\
\epsilon_{ij} &= \frac{4\epsilon_{ii}\epsilon_{jj}}{(\epsilon_{ii}^{1/2}+\epsilon_{jj}^{1/2})^{2}} \\
R_{ij}^{0} &= \frac{ (R_{ii}^{0})^{3} + (R_{jj}^{0})^{3} }{ (R_{ii}^{0})^{2} + (R_{jj}^{0})^{2} }
\end{align}
$$
and also considers up to permanent and induced quadrupole moments
$$
\begin{align}
U_{\text{elec}}^{\text{perm}}(r_{ij}) &= M_{i}^{T} T_{ij} M_{j} \\
T_{ij} &= \begin{bmatrix}
1 & \frac{\partial}{\partial x_j} & \frac{\partial}{\partial y_j} & \frac{\partial}{\partial z_j} & \mathrm{L} \\
\frac{\partial}{\partial x_j} & \frac{\partial^2}{\partial x_i \partial x_j} & \frac{\partial^2}{\partial x_i \partial y_j} & \frac{\partial^2}{\partial x_i \partial z_j} & \mathrm{L} \\
\frac{\partial}{\partial y_j} & \frac{\partial^2}{\partial y_i \partial x_j} & \frac{\partial^2}{\partial y_i \partial y_j} & \frac{\partial^2}{\partial y_i \partial z_j} & \mathrm{L} \\
\frac{\partial}{\partial z_j} & \frac{\partial^2}{\partial z_i \partial x_j} & \frac{\partial^2}{\partial z_i \partial y_j} & \frac{\partial^2}{\partial z_i \partial z_j} & \mathrm{L} \\
\mathrm{M} & \mathrm{M} & \mathrm{M} & \mathrm{M} & \mathrm{O}
\end{bmatrix} \left( \frac{1}{r_{ji}} \right)
\end{align}
$$
along with the other typical bonded terms found in modern force fields.
Here is a nice set of notes that describes the interaction between electric multipoles to different orders.
Comment: Just keep in mind that the potentials for Keesom force and Debye force here are all averaged for ALL angles. The exact dependence on the inter electronic distance w/o being averaged are here: http://www.chem1.com/acad/webtext/states/interact.html


What is the difference between Wahhabism and Salafism?

Question: What is the difference between Salafism and Wahhabism?
(As I know they are different from Sunnis. So what is their opinions?)
Comment: See [what is Wahhabism?](http://islam.stackexchange.com/q/1579/)
Comment: Why shiites are not stating that their answers are from there point of view?!
The fact that shiites  demand a sunni opinionated answers to state its orientation and not committing themselves to it, is really unacceptable
Answer: Salafism is more of an ideology - and sometimes a movement - rather than a denomination. The basic idea is that the first society ("Aslaaf") established by the Prophet of Islam (puh) himself was exemplary and as such mimicking its qualities is tantamount to "returning to true essence of Islam." Outside polemics, there is no such claim that each and every member of the society was par excellence, but rather that the collective "righteousness quotient" (RQ) of the forebears was par excellence. The scope of Aslaaf varies but is generally limited - in the light of Ahadith - to first three generations of Islam.
The Salafi idea can have different interpretations, i.e. what to look for in Aslaaf and how to apply that to present times. Consequently, there is literalist Salafism, which puts more emphasis on a literal reading of the scriptures and early culture and replicating their practices. In opposition, progressive Salafism (al-salafia
al-taqaddumiyya) - also neo-Salafism - is found in Modernists and differs as they understand the early society in the light of Modern ideas and posit a "returning to the true essence of Islam," by replicating the thinking of Aslaaf not practices.
Another class in Salafis is Quietists, which focuses on scholarly reforms as compared to political activism. As always, in reality, a spectrum between the opposing poles exists.
Corollary: As an ideology Salafism is not orthogonal to a sect, in particular Ahl-ul-Sunna. As a matter of fact, on close inspection, the core ideas of Salafism emerge in different, often strange, contexts. Personally, I find the core precepts of moral Sufism to be a call to "return to the spiritual moral purity of Aslaaf," i.e. Spiritual Salafism.
Corollary: In regular usage, Salafism can only be understood with reference to the "problems" that are seen and therefore the "solutions" that are posited to "return" to the true spirit of Islam.
Wahhabism is a realization of the literalist non-Quietist blend of Salafism - as a movement - who see moral decline, corruption of Creed, shutting down of Ijtihad and innovations as degeneration from Aslaaf. (None of these were newly discovered by the founder of Wahhabism) In the beginning the solution found was solely active religious reform but eventually engulfed political activism by forming a politico-religious alliance with Al-Saud (the ruling monarchs of Saudi Arabia). This alliance may be considered as the true defining moment of Wahhabism for later times.
Answer: There is no difference between any of them.  As for Wahhabism or Al Wahabiyah, it is attributed to Muhammad bin Abdul Wahhab, this name is not a name that it's followers call rather it is  name which was coined by those who were against it.  As for the Salafiyah it is a methodology which follows the Salafussalih, and there is no difference with what is known as Sunni.
So there is no difference among them, and I will not go into details as the answer would be quite long.  In the end the point is in not the names but in what they follow and mean.
Comment: can you add some reference?
Comment: Just to make it clear, *"There is no difference"* in the answer is for *"salafism and wahhabism"*? Or salafism and sunni (which I don't think as you made it clear in the answer)? wahhabism and sunni?
Answer: <code>                                    بسم الله الرحمن الرحیم
</code>
Muhammad Husayn Ibrahimi defines Wahhabism in his "A New Analysis of Wahhabi Doctrines" as such:

Wahhabism has been labeled with many various names among which is the
  appellation, "Salafiyyah". This name is used because they believe that
  for the reformation of their religion and beliefs, the present Muslims
  must go back to the early period of Islam ("Salaf" means the past or
  preceding one). Ibn Taymiyyah has introduced the issue of"Salaf" and
  his statements are a source of Wahhabi doctrines.
By "Wahhabism" it means that Shaykh Muhammad ibn 'Abd al-Wahhab must
  be followed in socio-political and religious issues because he has
  taught his followers the way to reform religion and society.

Muhammad al-Tijani al-Samawi also has explained this issue in his "The Shi'ah are the real Ahlul-Sunnah":

These are members of the largest Muslim community; they represent
  three-quarters of the total population of the Muslims of the world,
  and they are the ones who refer for religious verdicts (fatawa) and
  for religious following of the Imams of the four sects, namely Abu
  Hanifah, Malik, al-Shafi`i, and Ahmad ibn Hanbal.
Later in time, those called Salafis branched out of them; the
  characteristics of their beliefs were later revived by Ibn Taymiyyah
  whom they call "the one who revived the Sunnah," then by the Wahhabis
  whose ideology was invented by Muhammad ibn Abd al-Wahhab; theirs is
  the sect of the present rulers of Saudi Arabia.

Many scholars believe that Wahhabism is a sect of Salafism. Muhammad al-Tijani al-Samawi says in his "All Solutions are with the Prophet's Progeny":

It is worth mentioning to say that the deeds of the Prophet's
  companions are an argument against the Wahabis, because they believe
  that all the companions are totally just and honest. They claim that
  they follow them. They call themselves as Salafis meaning that they
  follow the "pious ancients" and that all the companions were pious and
  righteous in their view.
Answer: You stated that "they are different from Sunnis", that's not true at all, Sunnis follow four schools of thought, what people call "Wahhabi" or "Salafi" also follow these four schools of thought.
"Wahhabi" is actually a derogatory term for a "Salafi" so let me end its use now.
The above being said, if Salafi and Sunni is the same, then why have they been categorized separately?
I can give you an example that will help you understand, consider the term "Islamist", an Islamist is a Sunni, the Islamist follows one of the four Sunni schools of thought, just like a Salafi, but an Islamist is put in a separate category, why? An Islamist is a Sunni, but what is the difference between a none Islamist Sunni and an Islamist Sunni?
What is the difference between a Salafi Sunni and a none Salafi Sunni?
There's none, a Sunni follows the four schools of thought, a Salafi Sunni follows the four schools of thought, the Islamist Sunni follows the four schools of thought:

Hanafi
Hanbali
Shafi'i
Maliki

The answer you chose makes false accusations against Sunnis who are categorized as Salafis, for example saying: "they believe that all the companions are totally just and honest", this is a false statement quoted from a person who is a Shia.
Salafis don't believe all prophet's companions are "totally just and honest", rather they believe the prophet's companions are the best of men.
They didn't invent this, they got this from a Hadith, that's why they're "Sunni", because they follow the Sunnah and teachings of the prophet:

"The best of men are my generation, then those who come next to them, then those who come next to them. Afterwards people will come who will give testimony before swearing an oath, and swear an oath before giving testimony." (Bukhari and Muslim)

The above Hadith refers to the Sahabah, and this is why Sunnis not only respect but also trust the Sahabah, because as the prophet said, they're the best of men.
Hanbali is one of the Sunni Schools of thought, Hanbali derives its decrees from Quran and Sunnah, and also considers the opinions of the Sahabah.
The above being mentioned, why aren't Salafis called Hanabli instead?


Need help for maximizing solution

Question: Suppose there exists a list of unsorted int numbers [91,89,90,90,90,89,91].
I need to maximize the profit by selecting an element, in as many steps as needed, which satisfies the condition that,
when element(i) is chosen, the profit would be value of element(i) multiplied by its frequency/occurrence in list, an extra condition is that element(i), element(i)-1 and element(i)+1 should be removed as well.
So for the given array [91,89,90,90,90,89,91], if I choose 90 and remove it, my profit will be 90*3=270 and my array reduces to [], because I remove (90-1) and (90+1) in the same step.
However, if I had chosen, 89 then profit would be 89*2 and upon removing 89 and 89+1(There is no element corresponding to (89-1)), I am left with [91,91]. In the next step, I remove 91, this results in a total profit of 89*2+91*2. The profit is greater than the one obtained after selecting 90.

Another example is list [3,4,2], suppose I select 3, this means profit is 3*1 and I remove 3, 2 and 4 which results in empty list and profit is 3. Now, I choose 2, this results in removal of 2 and 3, profit will be 2*1. List will be [4]. Next step profit will be 4*1, so total profit will be 2+4=6.

I tried to select max element in array and remove it, but it will not work for list [1,1,1,1,1,1,1,1,1,2]. Here, 1 needs to be selected, instead of 2.
Because selecting 2, would result in a profit of 1 versus selecting 1 which would give 1*9.
What approach would be ideal to solve this? Please provide your opinions.
Thank you
Answer: This is a special case of maximum weighted independent set on an interval graph. Another way to phrase your problem is as follows: choose a subset of your neighbors of maximal sum in which no two elements have difference exactly 1.
One simple way to solve your problem is using dynamic programming. First sort the list, and remove duplicates (but remember how many of each number appear in the original list). Now use dynamic programming to calculate the optimal solution for every prefix of the sorted list.
Comment: On this site we concentrate on describing algorithms, leaving their implementation to programmers. Implementing this particular algorithm will greatly contribute to your understanding of dynamic programming. The first step would be to come up with complete pseudocode, which is missing from my answer on purpose.
Comment: If I may ask, would you be kind enough to provide an implementation of this, since I am still learning the concept of dynamic programming.

Need help for maximizing solution


Register Achievement ok, Create Achievement Returns false

Question: I've just started implementing FB Achievements for my Game. I'm using the PHP SDK for my app.
I've successfully registered an Achievement using the following code from my class which subclasses the PHP SDK class:
<code>$URL = 'apps.facebook.com/<app_name>/ach1.html';
$AppID = $this->getAppId();

$Params = array('achievement' => $URL);

$res = $this->api($AppID.'/achievements', 'POST', $Params);
</code>
I can confirm this has been created via the Graph API Explorer:
<code>{
  "data": [
    {
      "url": "http://apps.facebook.com/<app_name>/ach1.html",
      "type": "game.achievement",
      "title": "Tutorial",
      "image": [
        {
          "url": "<app_img_url>/1-ach.jpg"
        }
      ],
      "description": "Tutorial Completed",
      "site_name": "<app_name>",
      "data": {
        "points": 1
      },
      "updated_time": "2012-07-13T16:05:44+0000",
      "id": "<id>",
      "application": {
        "id": "<app_id>",
        "name": "<app_name>",
        "url": "https://www.facebook.com/apps/application.php?id=<app_id>"
      },
      "context": {
        "display_order": 0
      }
    }
  ]
}
</code>
However when I try to create an achievement for myself it returns false:
<code>$URL = 'apps.facebook.com/<app_name>/ach1.html';
$UserID = 100000466230867;

$AccessToken = $this->getApplicationAccessToken();

$Params = array('access_token' => $AccessToken,
                'method' => 'post',
                'achievement' => $URL);

$res = $this->api($UserID.'/achievements', 'POST', $Params);
</code>
The result is "boolean false". No error code is returned. Am I doing something obviously or fundamentally wrong here? I've tried providing a 'display_order' of value 1 and 0 aswell.
I can confirm I've granted the publish_actions permission aswell.
<code>permissions:Array ( [data] => Array ( [0] => Array ( [installed] => 1 [email] => 1 [publish_actions] => 1 [bookmarked] => 1 ) ) )
</code>
My app is correctly configured as a game aswell.
Any help greatly appreciated!!
Cheers
Answer:
If the app is in sandbox mode, take it out.
Ensure the user has authorised & hasn't removed the app

'false' usually means 'Person or page whose access token you're using can't see the data you're asking for',
This happens most often for blocked users, apps in sandbox mode, deleted content, etc
In this case, i suspect the app can't see / interact with the user (if this a test user created via the app settings interface or API this is especially likely as test users have some strange privacy quirks)


Can I have sex with an unknown person if my husband has been abroad for around five years?

Question: My husband has been abroad for about the last five years and I am very thirsty for sex, but he is not here.  Can I have sex with another person?
Comment: I'll rephrase your question for you: Is zina haram if my husband is abroad for five years? do you still need an answer for that? If not than you might need to solve this issue with your husband, either you live together or you need to see each other more often, or you need to separate (divorce) and get married to somebody who could fullfill your desires and stay with you. As you see this isn't a question which is focused enough to answer here (see [ask]).
Comment: Nope, why don't you ask for a divorce instead and marry someone else?
Answer: You have good grounds for divorce, if there is no objection from your husband.  Then you could remarry and commence relations with someone new.  The tradition of punishment for adultery when married was public execution.  The sin is rated only slightly lower than murder.  These matters are found within the Qur'an, and common Islamic texts.
Comment: The *reason* of committing adultery dictates its punishment. Sometimes there is no punishment. See [this answer](https://islam.stackexchange.com/questions/36671/legal-system-does-sharia-command-courts-of-appeal/36895#36895). For this case I'm *guessing* there is a punishment but surely not the one you mentioned. Everyone can use Qur'an but if they are to draw conclusions it has to be in conformance to Qur'an itself. If there is a dilemma then they must seek guidance from a religious authority otherwise you would be making strict, radical conclusions.


Modifying fields for a Workflow Task in Sharepoint

Question: Does anyone know how you can modify the fields in an out-of-the-box (OOTB) Workflow Task (specifically Priority and Due Date)? The OOTB Approval workflow doesn't allow you to set these fields (it allows setting a due date, but not a due time).
I had a cunning plan to create a custom workflow in Visual Studio to set these fields automatically. This involved attaching my custom workflow to the tasks list and editing the tasks as they were created by the Approval workflow. However my custom workflow doesn't fire when new tasks are added to task list by the Approval workflow. And it seems you are unable to manually trigger a workflow on an item in the task list that was created by a workflow.
So in order to set the task fields as they are created by the Approval workflow I'd have to somehow hook into the OOTB Approval workflow directly, which I'm not sure is possible.
Obviously another option would be to recreate the Approval workflow from scratch with InfoPath and Visual Studio, but this seems like overkill to just add priority and time fields to the instantiation form.
Any thoughts?
Answer: I've just realised you can edit field such as priority and due date (time) from the task list by selecting Actions > Edit in Datasheet. This works for normal task list items and those created by workflow.
I'd still like to know why a custom workflow that is set to trigger on new items in a task list doesn't fire when a workflow adds items to the task list.
Note: To edit the time a task is due you need to modify the OOTB task list so that the Due Date field is a Date and Time rather than Date Only.


Is there any effect on mechanical waves by electromagnetic waves (and vise versa)?

Question: Do electromagnetic waves like light and gravitational waves (due to moon for instance) affect on mechanical waves like sound?
Can sound change the path of light?
Answer: Any physical phenomenon is potentially capable to cause some change to any other phenomenon, more or less directly. If it was not the case, the physical world could be divided into completely independent realms; there would not be the one single world we call Nature.
Practically though, many if not most of the actually existing interactions between systems can be ignored, or just treated as perturbations in models taking into account only the most important ones. This is because interactions happen in a wide range of order of magnitudes. For example you would not usually include electromagnetic interactions between Moon and Earth when modelling their respective motion, although it certainly does play some part in the actual interplay of the two bodies (both having a magnetic field). If you do not ignore negligible effects, well even nocturnal urban lighting does play a part by sending photons to the Moon, pushing it away from Earth!
As a side note, the fact that some interactions are so much less intense than others is very useful: it allows us to use them as measuring devices. As shown in another answer, we can use Schlieren photography as a straightforward way to display air density because indeed the path of light is altered by compression waves, but only marginally so. If the dependence of electromagnetic waves on air density was more intense, it would be more complicated to decorrelate both effects.
Answer: I can answer half your question in that a sound can change the path of light.
A change in the density of the air produces a change in the refractive index of the air and so a Schlieren photograph can make this visible.
Here is a YouTube video to show a sound wave produced by clapping.
Comment: Interesting video! So, can we say because electromagnetic waves change properties of material environment (for example light can increase temperature of the air), hence they can have effect on mechanical waves as mechanical waves depend on the material environment properties?
Answer: Yes, sound waves in a gas, liquid or solid can affect the light passing through it, as the motion of the atoms due to sound waves changes the atomic spacing, and this changes the index of refraction slightly. So the light would be diffracted and some amount of the light would experience a frequency shift up and a frequency shift down by the sound wave frequency.
The other possibility is that of electromagnetic waves creating sound waves directly. Here, the effect is much smaller: when radiation like light shines on a surface it exerts a pressure known as "radiation pressure" though again this is a very small effect.
In principle, though, if a wide-beam high powered laser were to operate in a repeating pulsed mode (with a power level low enough that it does not ionize or otherwise cause phase transitions like melting, etc) then the laser would cause a pulsed mechanical vibration in the surface due to the changing radiation pressure, thereby generating sound waves.


How much torque can a Boeing 747 apply when pitching?

Question: I know this is a weird way of thinking about / quantifying this, but I'm trying to figure out how much torque a 747 can apply to itself when it pitches upwards (turning about an axis from wing to wing, with the nose moving upwards). I figure it's equal to the lift times the distance between where lift is applied to the wings and the axis of rotation, but I haven't been able to find this data.
Comment: There are a great number of forces torquing a 747 at a time, almost entirely cancelling each other out (hence its stability). Are you asking specifically about the torque induced by the elevator's control surfaces, or also about other forces which would tend to counteract it?
Comment: Well, any good answer would need to consider both torque used to overcome rotational inertia and change the pitch rate, and torque used to overcome aerodynamic damping and maintain a steady pitch rate.  Also the "baseline pitch torque" needed simply to maintain linear flight.  Or approach the problem from the other end and look at the max elevator deflection and resulting lift coefficient and figure the aerodynamic force resulting and convert to torque by multiplying by distance to CG.
Comment: Raises the question are we looking at NET aerodynamic pitch torque in which case the pitch torque used to overcome aerodynamic damping and maintain a steady pitch rotation rate does not count, and likewise the "baseline" pitch torque used to maintain linear flight does not count-- in this case we can only count the pitch torque component that causes a change in the pitch rotation rate.  So what is the max possible delta pitch rotation rate?  I think you have asked a very hard question perhaps best explored in an accurate simulator.
Comment: The question was meant to be "what's the maximum torque it COULD apply to itself, when it's pitching as hard as it can." Total aviation newbie (less than a newbie, not even in the field whatsoever but working on a physics thought experiment).
Comment: Though it may be too late to edit the question now without invalidating existing answers, for your thought experiment you might want to be consider whether the flight path is constrained to be linear at the instant that the pitch torque is first applied, or whether the flight path is allowed to be already curving at that instant.  But, I saw in another comment that you were considering the plane to be rolling along on the runway on the landing gear, so maybe that answers that.
Answer: The pitching force is coming from the horizontal tail's downforce resisting the airplane's net nose down pitching forces, so the real question is how much downforce is being applied and how far away is the tail's downforce from the lifting forces holding the plane up.
For a given set of parameters, you need to know the All Up Weight, the Center of Gravity location, and the Neutral Point, which is the location of the (gaseous) fulcrum the tail has to work about.  The NP is defined as the longitudinal point at which pitching moments are zero, the "effective" balance point in other words, taking into account the center of lift plus/minus the effects of various pitching moments (airfoil pitching moment, fuselage lift, nacelle lift, thrust effects, flaps and gear hanging down, etc.) which result in the actual net downforce the horizontal tail has to produce to "hold the nose up" in a given steady state flight condition.
If you know the CG location and the all up weight, then the "torque" acting on the fuselage at the Neutral Point is simply all up weight times the distance between the CG and NP.
So if the plane weighed 700,000 lbs, and the CG was 20 feet forward of the NP (just a wild guess; I have no idea the actual number), the "torque" value, the nose-down pitching force acting at the NP, is 14 million foot pounds.  If the aerodynamic center of the tail was 120 ft aft of the NP (another wild guess), that works out to 116666 lbs of downforce required for stable level flight back at the tail.  Of course if you now pull pitch to raise the nose, you are accelerating the mass about the lateral axis now, so those forces go up temporarily.

The values will change with changes in configuration, weight, speed, etc.  Make a change that moves the Neutral Point forward, like adding thrust, and the torque value and downforce required goes down; airplane pitches up from the thrust application because the existing tail downforce is excessive. Drop the gear, which moves the Neutral Point aft, and the torque value and downforce required to counter it goes up; airplane pitches down from the drag of the gear because the existing tail downforce is insufficient.
As far as finding out what is a typical Neutral Point on a 747, good luck with that...
Comment: I think this answer could be improved by changing the label (and associated references in text) from "neutral point" to "center of pressure" (or "center of lift").  The center of pressure is the point where we can apply the lift vector without having to also add a pitching moment -- exactly what you've done.  If the CG is at the "center of pressure" then the tail downforce is zero.  The center of pressure moves in flight, thus the preference for using "aerodynamic center" instead, plus a pitching moment.  Regardless, the center of pressure is usually not the same as the Neutral Point.
Comment: In other words stable flight is often possible with the CG behind the Center of Pressure (but still ahead of the neutral point), thus causing the tail to generate an upforce rather than a downforce.  Related ASE answer -- https://aviation.stackexchange.com/questions/19388/what-is-the-difference-between-centre-of-pressure-aerodynamic-centre-and-neutra/19399#19399 .  See also https://www.av8n.com/how/htm/aoastab.html#sec-pitch-equilibrium (last two paragraphs).
Comment: Center of pressure just refers to the net median point of lifting forces.  Neutral Point also takes into account other pitch moment influences. A low thrust line applies a pitch up moment.  Less tail downforce is required. The NP is moved forward. Dropping the gear creates a nose down pitching moment adding to all the other forces to give a new overall moment.  This moves the NP forward. GG must always be forward of NP so there is a moment that must be opposed by tail downforce. Stabs on jets move LE down to go slower. If the tail was making up force, the stab would have to move the other way.
Comment: Regardless of whether tail is making upforce or downforce, lowering the LE of the stab will trim for slower flight.  Well, looks like we're heading for another ASE question here, "Is stable flight possible with tail creating upforce, i.e. with Center of Pressure behind CG".  Or "is it possible for CG to be behind Center of Pressure but still ahead of Neutral Point, yielding stable flight with the tail generating an upforce?"
Comment: Well that one has been beaten to death lol.  You could have CG at or aft of the CP but with a strong ND pitching moment induced by some other influence, like floats hanging down, forcing the tail to generate downforce to oppose, you would have some static pitch stability.  I've flown several airplanes with and without floats, and the increased pitch stability with floats installed is subtle but noticeable. The NP must remain aft of the CG in all flight regimes so the operating CG range has to take all that into account.
Answer: I assume you are asking about the NET aerodynamic pitch torque that the 747 can generate.  In this case the pitch torque created by tail just to maintain linear flight doesn't count.  Nor does the pitch torque created by the tail to overcome "aerodynamic damping" in the pitch axis during a steady-state (constant airspeed, constant bank angle, constant turn rate) turn.  All that matters is the maximum possible rate of change of the pitch rotation rate, and the aircraft's moment of rotational inertia in the pitch axis.  That is all the information that we need to solve the problem.  Any approach based on other information will lead to a much more complicated solution.
But even boiled down to these simple terms, the problem is very challenging.  It is very difficult to determine the maximum possible rate of pitch rotation.  This is perhaps best determined by experiments in a very accurate simulator, or in the actual aircraft.  Caculating the moment of rotational inertia in the pitch axis is trivial compared to determining the maximum possible rate of change of pitch rotation.
The above notes were aimed at the case where the wheels are off the ground.  When some of the wheels are on the ground, that introduces another complication-- or perhaps a simplification.  When the CG is so far forward that the airplane can only produce a negligible rate of pitch rotation on takeoff at some particular instantaneous airspeed, then the total aerodynamic pitch torque created by the aircraft in that configuration at that airspeed is equal to the pitch torque created by however much weight is still resting on the main wheels at whatever airspeed the aircraft is moving at at that particular instant, times their distance from the CG.  What CG position would cause the aircraft to only be able to cause a negligible rate of pitch rotation at takeoff at some particular airspeed, and how much weight is still resting on the main wheels at that instant, is another thing that might perhaps be explored in a good simulator.
The aerodynamic pitch torque the aircraft can create at a typical rotation airspeed would surely not be the maximum aerodynamic pitch torque the aircraft could create in any situation.
For example, to take a really exotic case-- when the aircraft is inverted at the top of a loop at a relatively low airspeed, gravity is helping to curve the flight path, creating a curvature in the relative wind which essentially has the same effect as bending the fuselage like a banana in the opposite direction (with the concave side toward the wheels/ belly), decreasing effective decalage or creating negative effective decalage.  This would increase the power of the elevator and tail to create an aerodynamic pitch torque, and create a high rate of change in pitch rotation rate, in the landing gear/ belly direction, while decreasing the power of the elevator and tail to create an aerodynamic pitch torque in the opposite direction.  A similar effect was noted in this related answer, which looked at the problem in terms of the elevator's ability (or inability) to keep the wing at a positive-lift angle-of-attack, rather than in terms of the maximum possible rate of change in pitch rotation rotation rate: What has happened to make me experience negative G with the control stick FULL AFT near the top of a loop?
Comment: The "torque" created by the nose down pitching moment, CG acting around the neutral point, is present continuously.  In level flight there is a static nose down pitching moment being opposed by tail down force.  If you pull on the stick, you increase the forces but it's a transient condition, same as turbulence.   In a 2 G sustained turn, the level flight static forces are simply doubled.
Comment: If it makes things easier, I'm only trying to figure this out at takeoff, and I'm happy to just get within a factor of two. I *was* under the impression that much of the torque used to lift the nose of the plane at liftoff is generated by the wings, but now I'm realizing it might be more generated by the tail?
Comment: At point of rotation it's almost all the leverage applied by the tail to lift the nose, pivoting around the main landing gear, so initially, the lever arm is tail-to-wheel. The "pivot" shifts forward somewhat during the rotation as the wings start generating lift. The peak downforce demand and torque force on the fuselage is about at the point the tail skid contacts the runway.When fuselages get broken on landing, from being "overtorqued" as happened with Beoing's DC-9/717 test a/c, on an Embraer 145  once,  it's on landing, when you add landing G force to the leverage and it's just too much.
Comment: @JohnK let's say we chose the CG is the pivot point to resolve our torques around.  This is a valid choice and arguably the one that makes the problem simplest.
 Strictly speaking  in level flight the net pitch torque is zero.  Aerodynamic nose-down pitching moment from wing is opposed by aerodynamic  nose-up pitching moment generated by tail; weight itself (or G-load) has no effect on anything.
Comment: @JohnK I'm not sure neutral point has any effect on anything no matter what point we choose as the pivot point for our problem, I don't think neutral point is really the same as the point where the airplane would fly with zero tail upload or download if the CG were located there.  Could be grounds for another ASE question.  I think neutral point is the point where the aircraft becomes unstable in pitch if the CG is moved there, and plenty of aircraft are stable even when flying with an upload at the tail.  That too could be grounds for another ASE question.
Comment: @JakeKurlander Ok if we are talking about at the point of rotation at takeoff then opposing (nose-down) torque generated by the landing gear comes into the picture so technically my answer should be modified to include that torque as well the change in pitch rotation rate.  When the CG is so far forward that the airplane can only produce a negligible rate of pitch rotation on takeoff then the total aerodynamic pitch torque created by the aircraft is equal to the pitch torque created by how ever much weight is still resting on the main wheels, times their distance from the CG.
Comment: The CG must always be forward of the NP to create a nose down moment that tail downforce opposes.  The only time the downforces is not present is in transient maneuvering states.  This is why, to trim to a lower airspeed, the LE of the stab has to move down, increasing its incidence, to maintain the same downforce at the lower speed.  If you slow down without increasing incidence, the plane pitches down.  If you fly with zero tail download, CG balanced on the NP, you are neutrally stable.  The plane won't trim to a speed, will drift any which way in pitch, and be extremely unpleasant to fly.
Comment: @JohnK It seems you are implying that the neutral point is the point where the tail would generate exactly no upload or download in linear flight. Is that really true as a general statement? Could be grounds for another ASE question. My impression is that many aircraft can be stable even when the CG is located is such that the tail would generate an upward force. Of course in such a case the CG still must be ahead of the neutral point or else the aircraft would not be stable.
Comment: @JohnK Could be grounds for another ASE question: is the "neutral point" the point where the tail downforce would go to zero in linear flight? Here's an interesting take on it-- see last two paragraphs-- av8n.com/how/htm/aoastab.html#sec-pitch-equilibrium
Comment: Yes if you look up any definition, the NP is the point at which pitching moments are balanced. If you placed the CG at that spot, there is no pitching moment up or down.  It's the center of lift PLUS/MINUS any external pitching moments that add or subtract to create a "net" center of lift. To have positive static stability in pitch you must have a pitching moment present, a nose-down torque, that is opposed by tail downforce. Speed up, downforce up, pitch up.  Slow down, vice versa.  It's what gives you a trim speed.  CG must always be forward of NP or your airplane is neutral or unstable.
Comment: @JohnK see my comments under your answer
Answer: Having been a commercial pilot and instructor for over 36 years I deal with this daily. The 747 or any aircraft is essentially balanced at the center of gravity. The positive moment will equal the negative moment on the cg.  The aerodynamic force created by the horizontal stabilizer is easily calculable and is based on the lift coefficient, surface area of the airfoil, velocity, air density (rho),  The forces can range from mere hundreds to thousands of pounds of force applied to the arm depending on these factors.  By the way the cg is generally about 17 to 25% of the mean aerodynamic chord of the 747 measured from the leading edge of the airfoil at the root.
Once the moment (torque) is calculated then pitch acceleration rates based on weight can be determined.  Rates of pitch are only of interest to pilots as they relate to controllability and stability so we don't worry about actual axial acceleration rates.  In this regard the farther to the rear the calculated cg is within the acceptable range (in relation to the center of lift) the more controllable and aerodynamically unstable the plane will be due to moments being closer to equal.   The farther forward, the more aerodynamically stable and more difficult to control (greater required forces) it will be due to greater nose down moment.
By the way, most planes are designed to fly with some nose down moment due to loading.  This creates a more stable aircraft.  The cg range is always ahead of the neutral point. In theory, were it not for the necessity to longitudinally stabilize the  aircraft very little horizontal stabilizer force would be required. So a small amount of down force is necessary to stay in level flight, by design. This additional downward force adds to the weight of all forces acted upon by the total lift forces.
Tex
Comment: It seems you are implying that the neutral point is the point where the tail would generate exactly no upload or download in linear flight.  Is that really true as a general statement?  Could be grounds for another ASE question.  My impression is that many aircraft can be stable even when the CG is located is such that the tail would generate an upward force.  Of course in such a case the CG still must be ahead of the neutral point or else the aircraft would not be stable.
Comment: Could be grounds for another ASE question: is the "neutral point" the point where the tail downforce would go to zero in linear flight?  Here's an interesting take on it-- see last two paragraphs-- https://www.av8n.com/how/htm/aoastab.html#sec-pitch-equilibrium
Comment: @Thetexan is exactly right.  The NP is the effective balance point about which the tail must react the moment created by the CG forward.  NP is the center of lift but adjusted for other pitching moments that may help or hinder the basic pitching moment of the CG-CL lever.  If I have a seesaw that is in balance on its physical pivot but I add an external influence, like a spring pulling down on one end, that tends to tip it one way, I'd have to move the pivot to a new location to make it balance.  This is the NP.  The NP must ALWAYS be aft of CG to have positive static stability in pitch.
Comment: "Trim Drag" is in fact the energy consumed by the tail to generate its downforce.  I can move the CG closer and closer to the NP to reduce the downforce required and thereby reduce trim drag, but I end up with diminishing stability, and to run an airliner with the too far aft like that I have to use electronics and software to drive the tail surfaces in the background to actively make up for it.
Answer: Is it possible  to have a stable aircraft (aerodynamically) in a condition where stabilizer updore is necessary for level flight?
No. Not by the definition of static or dynamic stability.
There are two systems that have to be considered.  The first is the wing itself.  The airfoil has a center of pressure that moves fore and aft based on angle of attack.  It also produces a downward force center of pressure due to Bernoulian and Newtonian forces on the bottom of the wing.  The upper and lower centers of pressure are not physically opposite of each other and therefore produces either downward or upward torque on the wing itself.  This torque is centered on the mean aerodynamic center.  The MAC does not move regardless of AOA. It it through this MAC that the center of lift operates.
Now take this wing with Its own system of balances and forces and attach it to a plane with its own balances and forces.  The CL will be behind the CG on most aircraft for stability purposes. Only when the CL and CG are at the same point will the NP be near the CL/CG point.  Since weight and speed determine necessary AOA, and AOA effects CP, drag, and stabilizer AOA the NP (or point where no stabilizer force is required for level flight) will never remain in any one location but will be at a different point based on a given set of conditions.  The odds of the CG and NP ever being and staying the same are improbable.
As to how much torque is required....torque is torque.  You can simple calculate the moments of a plane that is balanced.   The force required to move a 400,000 lb airplane about its CG will be a matter of F=ma.  That will give rate for a given force.  Calculate the force capable with a 747 stabilizer (per L=ClrhoV^2*S) and apply it to the force formula and that should be close to the rate or rotational movement around the lateral axis.  My angular momentum physics may be a little rusty.
Angle of incidence also plays into this.  Most airplanes have a positive AOI.  A B727 had an almost 1.5 degree down AOI.
That's why it always flew nose up compared to other planes
tex
Comment: Welcome to ASE.  It looks like at least part of this answer would be better posted to a different question; there are several existing questions on ASE that this answer might fit.  Also on ASE, people are welcome to ask a question and then self-answer it, so that's another option if you feel this answer best fits a question that has not been asked yet.  But consider this one -- https://aviation.stackexchange.com/questions/22087/do-any-airplane-designs-exist-that-dont-involve-a-flight-surface-that-provides
Comment: "A B727 had an almost 1.5 degree down AOI."-- really?  I wonder why.  I see another ASE question coming here...


Hiring security auditors...what should I know?

Question: I want to hire someone to do a security audit of my website but I'm not sure how to go about it.  Where are good places to look for an auditor?  Besides a list of referrals, what should I be looking for in an auditor?  What qualifications should he/they have, and how can I verify them?
Comment: Just to be clear, is there a specific kind of security audit you need?  For example for PCI compliance or something else?
Comment: I'm looking for something general -- I'm a solo developer and don't have anyone to review my code, but even if I did, I'd still want someone who knows more about security to bang on things.  I know enough (I think) to prevent SQL injection attacks, but I don't know what else I need to be worried about.  Someone, somewhere, must specialize in this stuff.  Who is he, how do I find him, and how do I tell if he's any good?
Answer: I'm going to suggest that you get yourself a copy of nessus and run the scans yourself.  It should give you a good baseline to start with.
Why?  Because many third party auditors are going to run this exact tool and won't really help you with interpreting the results any way.
If you use certain Verisign certificates, Symantec throws in some baseline vulnerability scanning as part of the cost. Other CAs may provide some of these services as well.
If you have a specific requirement like PCI Compliance, you can get a list of authorized scanning vendors with the caveat being that scanning results don't necessarily come with vulnerability management support (unless you pay extra).
Answer: There are IT security certificate issuing firms. I cant give a statement on the acceptance of those or on the skillset required.
Maybe a google search on "IT security certificates" reveals more information or a start for deeper DD.
A professional pentester/auditor should be able to prove the knowledge by such a certificate, a real diploma and/or job references.


Mass remove passwords from rar archives

Question:
Possible Duplicate:
How to remove password protection from compressed files

Is there a way to (I'm using WinRAR; demo, but I'm willing to change it to whatever is needed) mass remove passwords from a bunch of files ?
Problem description: for reasons unknown to me, some archiving was done for two-and-something years in RAR format, and all archives have passwords. I have a list of them, them all being similar (mostly something like John-03, John-04, John-05 ... e.g. name-month ...) but I need to manipulate the files at large, and it is a real problem removing and or dearchiving all those files, while entering passwords manually.
What would be my best options concerning ?
Ideally, I'm looking for some kind of archiver which tries out a predefined list of passwords, and asks only if non of them cracks the safe. Afaik, WinRAR has no such feature.
Answer: WinRAR comes with a command-line tool rar, which can be scripted to extract and re-create archives.

Mass remove passwords from rar archives


Can I use Type-S mortar and rock to set wood fence posts?

Question: I am trying to set a fence post by the house to fix up a gate door. The usual "bag mix" for this job is a mixture of quarter inch stone and cement and lime. However, I also have a bag of type S mortar that I haven't used and would like to use or be rid of. Would it be compromised or ineffective to use some stone and type S mortar to set the fence? or is there too much sand and lime in the mix?
Answer: If that is what you have, Type S will work just fine, the trick is that the fill around the post is preferred to be harder than the dirt that the post and cement is in. If there is any "scrap" bags of cement, or concrete that even has lumps in it, that is a perfect spot to make use of it.


How are Desmond's assassin ancestors related to each other?

Question: I read somewhere (cannot find the link at the moment) that Altair, Ezio and the Kenways (including Connor) are not directly related to each other except through Desmond. Is there any family tree or something to show how he is related to them?
If the Kenways are on Desmond's father's side, could he not have gone in the Animus as well in Assassin's Creed 3?
Answer: Here is a family tree of Desmond's ancestry (click on the picture to zoom in).
As you can see, the Auditore and Ibn-La'ahad sections of the tree are completely independent of one another (and their link is currently unknown).
It is not known how directly the Kenway portion of the tree connects to the others, so until future games reveal this link we will be unable to tell how well connected they are to the Auditores or Ibn La'ahads.
We can also see from the tree that the relationship to these ancestors is on Desmond's mother's side of the tree. So Desmond's father would be unable to use the animus to access their memories since he has no direct ancestral link to any of these families.
However, presumably any family member on Desmond's mother's side of the tree (from the generation after Connor to Desmond) would be able to access the same memories we have accessed from Desmond so far.
Hopefully the coming games of Unity and Rogue will help fill in some of these blanks on the family tree.
Comment: Someone bumped this question and I just noticed this anwser (which is pretty good). Although, in hindsight, it's 2016 and Unity, Rogue (and now Sindycate) completly shat on Desmond.
Answer:
And if the Kenways are on Desmonds fathers side, could he not have gone in the animus as well in Assassins Creed 3?

At one point in AC 3 Desmond angrily shouts that at his father

after it is revealed that  Haytham is a templar

Right before his father

punches Desmond in the face (something long overdue).

So that suggests the Kenway's are on Desmond's fathers side (at least in Desmond's mind - his father neither confirms nor denies).
As for why his father couldn't go into the animus, it's strongly hinted that there is something special about Desmond. Perhaps it is the convergence of blood lines from his mother and fathers side?
Comment: Quotes to show the strong hint he is 'special'?
Comment: @Samiko: I don't have an exact quote, but, for example, when Minerva speaks to Ezio she talks directly to Desmond (much to Ezio's confusion) suggesting it has to be Desmond in the animus
Comment: Ahha yes i remember now. Thanks, another great answer.


What is the most common way of administering loop diuretics and what is their time course of action?

Question: I am reviewing some material on loop diuretics, and I am curious to know how these drugs are administered. Also, I am interested in knowing their time course of action once they are administered into the body.
Answer: I know that furosemide (there are more types of loop diuretics) can be given intravenously (but can be orally given as well (furosemide info sheet)). Effects of i.v. furosemide are pretty much immediate as it is carried quickly to the kidneys via the blood. After i.v. administration the effects wear off in about half an hour. t1/2 is about 2 hours, but likely depending on route of administration.


Import from CAD System

Question: Which experiences and hints do you have when it comes to importing data from CAD systems like Siemens NX, SolidWorks, SolidEdge and so forth?
I'm struggeling with this topic for one week now and just found the suitable solution of STL files. This comes with the downside of having tons of triangles where one single face would be sufficient, a huge file size and overall only flat surfaces which looks ugly with round objects e.g. tires.
I just found out after trying a lot of combinations and options today, that NX has a well usable DXF export when it comes to curves and faces. They are even importable to blender as connected real splines. I was kind of astonished.
The downside is...exporting the volume body itself was not not of that charme. The body is made of flat faces and the resolution value is not respected. Whatever one inputs the resolution of the volume body remains constant.
VRML export has a usable resolution/tolerance value input option that works out fine. The wrl file gets imported in blender nicely. Downside: every connected face (all faces are flat) is an extra object. Joining the objects together is necessary. I also experimented with the wrl file in MeshLab and exported it from there to Collada, PLY and CTM files. The compression with CTM worked really well and didn't loose any visable faces or vertices. Also loading went like a charm. Faces as single objects issue remains, though.
Answer: The best solution I have found is .FBX.  Tried a lot of others including OBJ but settled on this.
In my case, SolidWorks files opened in Rhino, saved as .FBX, import that into Blender.
There are lots of export options when saving to .FBX in Rhino, had to set Maximum Angle to 2.0 (instead of 1.0) in order to get the rounded surfaces to appear round, and not jagged.

Import from CAD System


Steps to making first share purchase?

Question: I would like to know the steps I can take to buy shares, for a common man having a bank account and PAN card.
Answer: You need to establish a brokerage account which you can do at your bank at a desk different from the one you usually go to for bank services, or at an independent brokerage not affiliated with your bank. They will tell you what to do next.
Answer: All major private and public sector banks in India have share brokering arm. Most probably the bank you bank with will also have the same. As mentioned in the above post, most banks are full service brokers i.e. they provide you with reports and market sentiments from time-to-time (though their usefulness is a matter of debate). They also charge you higher brokerage on buy/sell leg, with SST it could come as high as 0.8% per leg (though it varies between brokers). On the other hand there are discount brokers, who usually charge a fixed fee e.g. INR 20 per transaction.
However, having said about the brokers, a DMAT account with NSDL/CDSL (depositories) will be opened and the shares you buy and sell will be credited/debited from your depository account. The brokers will provide you with a web platform to conduct your transactions. To open the depository A/C and the trading portal A/C approach your bank or any of the discount brokers. With some of the discount brokers, the entire process can be on-line with signed documents sent to them later. For opening the account you would need ID proof, address proof, PAN card.
Answer: Its very simple.  There are many brokerage firm in India dealing in NSE & BSE.  But you should consider the following before choosing a brokerage firm for opening DMAT account.

Reputation of broker : because whenever there is a crash in the market, the brokerage firm account freeze due to margin requirement.  Such thing happens with the brokers who provide over leveraged ( margin ) to the customers for over trading.
Brokerage : If you want to be an active trader, the brokerage is an issue you should care for.  There are two types of brokerage firm, (i) Traditional like, IIFL, Sharekhan, Trustin and so on ( you can google "open DMAT account online"). (ii) Discounted brokers they are like R.K. Global, Zerodha etc.  The discounted broker allow you to trade at fix rates.  For example Rs.9 per order or Rs.20 per order irrespective of the amount of your trades.  Such types of brokers are very useful for active traders.

CAUTION : First learn how to invest in stock market like fundamental investment or technical analysis trading otherwise it is like driving a car without knowing driving which will certainly cause accident.  Your whole amount can be zero without any knowledge.  Every new trader or investor does it.

Steps to making first share purchase?


Android Market disappeared! How do I get it back?

Question: Since upgrading to FroYo, the Android Market app has disappeared from my wife's Droid X: it doesn't appear on the home screen or in the Applications list in settings. Is there any way to get it back?
Comment: In what way has it "disappeared"? Do you mean it no longer appears as a shortcut icon on the home screen?
Answer: It's a built-in app and can't be uninstalled.
To restore the icon to the home screen, find the icon in the application list and long-press, then drop it where you want it. Alternately, long-press the home screen where you want the icon to be, choose "Shortcuts", then "Applications", then the "Market" icon.
Update: Okay, it appears that you're not the only one with this issue. See this thread on the Google support forum: http://www.google.com/support/forum/p/Android%20Market/thread?tid=3322620a3c715568&hl=en
One offered solution is to do a factory reset. It's up to you to decide how comfortable you are with that.
Update 2: Several people in this thread said that the factory reset worked for them. Additionally, someone wrote a script (also in that thread) to fix the issue, which you would need to get on the phone. (USB would seem to be your best bet.) Caveat Emptor. Someone also mentioned that if you get the Vendor.apk you can also get the Market back. (Details are a little fuzzier.)
Comment: It really seems to be gone, as if the upgrade uninstalled it.
Answer: from here I tried  http://androidforums.com/droid-x-support-troubleshooting/196653-help-market-place-gone.html
To get the Marked app back, without doing a hard reset.
used ASTRO file manager

Opened ASTRO, clicked Up
navigate to /system/app
Locate Vending.apk
push on it to install it, clicked ok etc

Now back on home screen, follow what is suggested about a clean slate ...

Settings -> Applications -> Manage Applications
Chose All
Find Market
Push on it and select Clear data
go back to main home screen, turn your phone off and back on
Comment: Worked great! I had to power cycle the phone before the Market would run though.
Answer: If you are running stock Android I believe you are going to have to do a factory reset.  If you are rooted and running some custom mod, you can probably just install the googleapps.apk or reflash the rom.
Answer: I just figured it out, very easy.  The Android Market is now called "PLAY STORE" by Google, and is listed under "P" in your phone (not "G" for Google Play Store).  Just go into all your apps, go down to "P" and long hold the "PLAY STORE" icon to get it to your home screen.  This icon looks like a white shopping bag with handles and a blue, red and tan diamond/pyramid figure on the front.  GOOD LUCK and have a great day.
Comment: @AlEverett This question will show up in Google searches for people who've just lost the Market icon due to the recent update. For that reason I think this is a valid answer?
Comment: Please note: This question is from November, 2010. That the Market was just renamed to Google Play is obviously not the answer to this question.
Answer: My android market icon dissapeared when i clicked on it yesterday on 2.2  i just read today in the news that google changed the name from Android market to Google Play to get more customers focused on its videos and books.  I found a brand new icon in the second apps location on my phone.  It is called google play not called  android market any longer. All you do is click accept and use.....
Comment: Note the date of the question.


How do you fix a non-working key on the Macbook pro 2016?

Question: I have a Macbook pro 2016 and keys keep getting stuck. By "stuck" I mean that pressing them doesn't do anything anymore unless I press them really hard. The recommended way is to blow air into the keyboard while holding it at a certain angle. I never have a can of air laying around, and blowing with my mouth doesn't seem to work. Is there a different way?
Comment: Possible duplicate of [MacBook Pro 2016: Keyboard key stuck – how to remove key?](https://apple.stackexchange.com/questions/272038/macbook-pro-2016-keyboard-key-stuck-how-to-remove-key)
Comment: Replace the top case.
Comment: Bring it into an Apple Store or setup a mail-in repair and they will fix it.
Answer: I found another way that seems to work and doesn't require a can of air: Hold the laptop sideways and while holding it like that, pound on the key. Pound as hard as you would if you were typing an angry message. Try to pound on each side of the key. Holding it sideways gives gravity a chance to pull the crumbs out. And if it doesn't work the first time, try holding it a different direction.
I've tried this method on several keys, including the large right SHIFT key. It seems to work pretty good. The SHIFT key still isn't fully back to normal, but is way better than it was.
Comment: Just a heads up, while this may work, it may very well also cause damage to your laptop. If I were you, I'd look into ways of removing a key to clean under it, then reapplying it.
Comment: How would this cause any damage, as long as you aren't pounding harder than the keyboard was designed for?
Comment: Because the keyboard was not designed to be held sideways and pounded. Using things outside their intended scope always leaves them susceptible to damage.
Comment: I only had to type as though I was mildly disappointed to get it to work.  Please don't remove the key, as that is more likely to void the warranty than typing.  Also, obviously, don't pound the key hard enough to cause damage.
Answer: Take it to Apple, who will do a free repair under their keyboard service program.
Comment: Yes. Have done this before and will probably need to do it again. It's just a hassle and I was hoping to find a way to minimize these trips.


Was the Progress spacecraft named after the research facility, or vice versa?

Question: "Progress" is used as the name of a Russian space research facility and factory (the Progress Rocket Space Centre), and also as a spacecraft that delivers cargo to space stations (Progress spacecraft).  Was one of these named after the other?  (It is not clear from the Wikipedia articles.)
Answer: Following the trail back in time, Progress Rocket Space Centre -> TsSKB-Progress -> Progress plant, named by the Ministry of General Machine-building in 1965.
As that's before the spacecraft (programme initiated in 1973), the centre is at least not named after it.
Though the word "progress" is pretty generic, both the plant and the program were in the same branch of the Soviet design bureau hierarchy, so I can sadly not rule out that the spacecraft was named after the plant.


Android:How can i change the color of the text of the ListAdapter?

Question: The default color of the text is white. Let's say if i want to change the color, then how can i do it? Any clue?
Answer: in the getView method, find your TextView and  set the color via setTextColor().
If you want your color changed for you based on the state of the item ( selected/focused etc) create new color in my_color.xml and define your states - examples of stateful colors are in SDK in res folders.
Answer: One thing you could do is use your own layout for the list items. This way you could set whatever color or any other layout in the items.
Answer: You couldn't use setTextColor(); in your ListAdapter ? I think you could
Answer: I highly recommened writing your own theme for the list view and then setting it in the layouts xml file, this means that you can use the same style throughout your app
This is a good tutorial to start with
http://brainflush.wordpress.com/2009/03/15/understanding-android-themes-and-styles/


Is an editable content query possible?

Question: I am using our SharePoint site as a learning management system for training newly hired employees.  Our set us is a subsite that contains 25 site pages (one for each student).  Each page contains a unique Document web part so that each student has a unique copy of a curriculum document (an editable PDF).  Right now, I create each class as a template but when I update curriculum items, I have to update it in all 25 document libraries.  I'm wondering if there is a way to dynamically populate the document libraries (like a content query) from a central library?  I'd use a content query but you can't have your own copy of the document that I know of.  If Student 1 checks out something, Student 2 can't and if they could, they would overwrite Student 1's work.  I'm hoping for a more automated way to populate each document library.
Answer: If I'm understanding correctly, you could just create a manual workflow that will copy the pdf or items to each site.
Comment: That's interesting Chris.  So (forgive me if I'm about to sound dumb), could a customer workflow act as a type of "script" that will do this work for me?  Could a workflow be programed to create a "class" and assign the content?
Comment: That's correct.  SP has a workflow that I have used that copies one item, and can copy that into several places.  I'd like to be able to select multiple documents and do the same thing.

Is an editable content query possible?


IDE does not create prototypes

Question: I'm running Arduino IDE 1.6.10 on Mac OS X 10.12.1.
I read on the Arduino official sote that the IDE should create function prototypes for me, and it always did. But now I'm writing a 1500 lines program, with dozens of functions, and this tool wold be quite useful (although I obviously don't really need it)... and it doesn't work.
Is that a known issue?
Answer: There are some times when it can't make prototypes, and some when it just gets it plain wrong. It struggles if you do fancy things with any of your functions, such as adding attributes or using anything that's even slightly out of the ordinary.
Also sometimes it places the prototypes in completely the wrong place, especially if you are working with structs, etc.
Answer: Do yourself a favour and dont rely on those automatic tools.
Type your code and know every line you typed.
And give PlatformIO a try instead of the Arduino IDE. You will save yourself and coworkers a lot of grief.
Answer: Unfortunately various things make the prototype generation fail. I think they run a regexp on the code which doesn't detect all cases. Examples are:

Function definition split over multiple lines
Use of templates
Use of user-defined types in a function definition

Here is one bug report:
https://github.com/arduino/Arduino/issues/472
It's not that hard to take your function definition and make a prototype out of it. It's good practice anyway to get into the habit of it. If you get into larger projects where functions are in different files you need to do this anyway.

IDE does not create prototypes


What type of wall texture is this, and how do you remove it?

Question: What type of wall texture is this called?
What is the best way to remove it so I can replace it with orange peel?
Answer: That looks like skip trowel. Regardless, your solution depends on if it's plaster or drywall mud.
If it's plaster, you can skim coat it or have it removed and reapplied. Both require a bit of skill and it's best done by a professional. This will not come cheap.
If it's just mud, a skim coat is fairly easy to do but takes time and patience. You can thin down some ready mix mud, apply it with a 3/4 nap roller, then scrape off the excess with a 12" drywall knife. This will probably take a few coats, but it can be accomplished by a diyer. After you have the wall to mostly smooth plane, prime with PVA and you can apply your orange peel texture. Then just prime and paint.
Another solution is to put on 1/4" drywall directly over it. But this is a big job with taping seams, altering trim around doors and windows, extending electrical boxes, and applying texture.
Just to cover all options, it's "possible" to sand smooth. Even renting a power sander hooked up to a shop vac, this will produce a lot of dust. Plaster and certain drywall mud types are really hard to sand. I wouldn't do it.
Also, I would rent a texture sprayer. The cans of texture are really only for touch up and the fumes are pretty bad. Mask off with builders paper or poly sheets anything you don't want texture on. It's all in the prep work.
Comment: I agree In the past I have applied similar coatings some with plaster some topping mud , if it can be knocked down with a butter knife it is mudd and can be sanded. If it feels like cement it is plaster, can still be sanded but much more work. Don't agree on adding more 1/4" to the wall because of electrical outlets, switches and lights.


How and why does Jason Bourne find Marie at the end of The Bourne Identity?

Question: At the end of The Bourne Identity we see Bourne find Marie somewhere in Greece, even though she is in hiding. How does he find her? If he can find her so can other agencies. Why would he do it if he knows he will put her in danger again?
Comment: Are you trying to find out how he found her or why?
Comment: @sanpaco well...both :)
Comment: Bourne finds Marie after 6 months, he may have searching for her ever since..
Answer: Why?
Well clearly he's in love with her and that is what provides his motivation for finding her.
Regarding the danger aspect, well at the end of The Bourne Identity he has taken out every operative the Treadstone program has thrown at him with pretty extreme prejudice and in addition to the significant losses he has inflicted to their operation they no longer have any active leads on him so it's not unreasonable for him to assume that if he's sensible and keeps a low profile (and he's highly trained at doing just that) that he'll be able to stay ahead of them. Certainly he's better equipped to do so than Marie is on her own and given that they already know about her and have her picture etc and know that regardless of whether she is physically with Bourne she is a lead/leverage worth pursuing she's actually probably safer with him then without.
Spoliers for The Bourne Supremacy :

 And as we see at the start of the second film this approach works well for 2 years,  it's only when Kirill (who is very nearly Bourne's equal in skill) with his access to Russian FSB resources and the likely Arbitrarily Large Bank Account of a Russian Oligarch gets involved that Bourne's safeguards fail.

How?
He's a highly trained former spy/assassin. Tracking down his "target" is likely to be something they covered in that training. Marie is a civilian who has only minimal instruction in how to hide so for him to be able to track her down in ~6 months isn't a massive leap.
Comment: He also knows that she had been working in a surf shop before they met and she has been taking good care of her car. So somewhere by the ocean (surf), somewhere you can get a job without having to worry about having papers checked (small Greek island) and a service job she'd be good at. She can do some scooter repairs keeping them in a good shape, she has experience in a customer facing role, so selling coffee is an easy choice. (Come to think of it, what took him so long).
Comment: @Bent not sure, it's an excuse to watch them again!
Comment: @Bent, not sure if you're joking or not, but I'm curious about the bit about "working in a surf shop before they met". Is that mentioned in the films? I've seen them all a dozen times and never noticed a line like that.
Comment: @Darren Didn't she get scammed by someone with a surf shop? I think she mentions it at the embassy when she is trying to get a visa to the US before she meets Jason or she mentions it to Jason just after they met.
Comment: How exactly being in one of the most visited tourist places in Europe can qualify as keeping a low profile?
Answer: In car driving to Paris Marie talks about surf shop experience at Biarritz -> she likes it at the beach.
After the huge car chase in Paris they book a hotel and Marie wears a Corfu t-shirt. It is a small island in greece. Ok for laying low.
Marie is in love too and knows of Jasons remarkable observational skills, so it's a given he will recall the t-shirt.
That's in my opinion where they could be in the end. Otherwise it's a bit too hard to find even for JB.
Comment: Once again the accepted answer is a word salad and the answer that precisely answers the question is at the bottom.


Ensuring a minimum version with use-package

Question: In my .emacs, I would like to ensure that the s package, version 1.10.0 or newer, is installed. If I use (use-package s :ensure t) it will not upgrade the installation on systems with older versions of s. How do I ensure that the minimum version is present?
Comment: I do not think that use-package supports this.  It's rather unusual to have minimum version bounds in a personal configuration, because most people update regularly anyway.  And with MELPA version bounds don't really work anyway.
Comment: I looked in the `use-package` source and there doesn't seem to be an obvious way to do it with `use-package`. Is there another way to do it?
Comment: Well, sure, there's always the package.el API which you can use to update a package programmatically.  That's not a nice API though so consider whether it's really worth the effort.
Comment: I am assuming that mass updating all the packages from Melpa/GNU Elpa does not apply to your use case?
Comment: I have a single `.emacs` which I share among many environments. They all already have an old version of `s` installed. When I load Emacs next in each of these environments I will get errors due to missing functions in the old version that I would rather avoid. Yes, I can fix them by doing a mass update from the `package-list-packages` interface one environment at a time. Just like before I had `use-package` I would have installed the packages one environment at a time.
Comment: Don't you want all your environments to be running the *same* config, so that you can have consistent behaviour everywhere? If you put your config under version control, all copies can be identical, without worrying about tracking individual version numbers.
Comment: My `.emacs` is under version control. Are you suggesting putting my `elpa` directory under version control also?
Answer:
This solution does not invoke use-package, but instead uses the included package.el functionality.  Either way it should get the job done:
;; (source: http://emacs.stackexchange.com/a/22174/93)
(defun package-update (package &optional version)
  "Update a package from the package archives.
If VERSION is nil, update the package to the most recent version
available.  Otherwise, VERSION should be a version string, or a
list of the type returned by `version-to-list'. The package will
be updated only if the currently installed version is less than
the version specified, even if a newer version is available."
  (unless package--initialized
    (package-initialize t))
  (unless package-archive-contents
    (package-refresh-contents))
  (let* ((current (cadr (assoc package package-alist)))
         (current-version (if current (package-desc-version current) '(-1)))
         (pkg-desc (cadr (assoc package package-archive-contents)))
         (pkg-version (and pkg-desc (package-desc-version pkg-desc)))
         (target-version (or (and (stringp version) (version-to-list version))
                             version
                             pkg-version)))
    (when (version-list-< current-version target-version)
      (if (null pkg-desc)
        (error "Package `%s' not found in package archives" package))
      (if (version-list-< pkg-version target-version)
        (error "A suitable version of `%s' is not available" package))
      (package-install pkg-desc)
      (if current
          (package-delete current)))
    nil))

With that function defined, you could add the following to your init
(package-update 's '(1 10 0))

to ensure that your currently-installed version of the s package is at least version 1.10.0


How deep is the Underdark? What is its max and median depth?

Question: How many miles under the ground do the Underdark tunnels and caves typically go? One? Five? A hundred?
Answer: At least 26 miles deep, with rumoured unexplored caverns 40 miles deep, though most of the known Underdark is within 10 miles of the surface.
According to the D&D 3e sourcebook Underdark, p.120, the lowest level of the Underdark starts at a depth of ten miles and continues down from there:

No place on Toril is as strange and dangerous as the Lowerdark. This level of the Underdark extends from 10 miles below the surface to unfathomable depths and features a degree of strangeness that would drive some surface dwellers insane.

At this depth, it is described that tunnels and passageways become rarer. Since this is the bottom of the Underdark, the typical depth of Underdark locations is between 1 and 10 miles beneath the surface. For example, the city of Menzoberranzan is only 2 miles below the surface, and is considered part of the Upperdark.
Deepest locations
Portals to the plane of Shadow (what would in 5e be called the Shadowfell) are stated to exist at depths of 15 miles or below. A sea flows 20 miles below the surface (p.123):

The Glimmersea lies 20 miles below the floor of the Sea of Fallen Stars.

Even deeper is the Genasi city of Earth's End (p.147), although it cannot be reached without teleportation and has no direct tunnels:

Situated nearly 22 miles beneath the Nath in Halruaa, Earth's End is unapologetically designed for its extraplanar visitors.

Oryndoll, City of Loretakers, is just over 26 miles deep (p.168).
There's also an abyss beneath Anauroch, named Lorosfyr, the Maddening Dark, rumoured to be at least 40 miles deep in places (p.160), though it it unexplored.
Comment: Is the Sea of Fallen Stars a real sea? If so, I'd expect its floor to be deeper than the surface.
Comment: @MatthieuM. I belive its depth is on the order of hundreds of feet, so the difference between surface and floor isn't very significant compared to 15 miles.
Comment: @MichaelRichardson: Ah indeed; similar to the "Channel" then, between France and England, which can be as deep as *gasp* 120m (~400 ft.)
Comment: @MatthieuM. I may be seriously underestimating it depth, as I was picturing it as the Mediterranean Sea and seriously underestimated the greatest depth there.  However, while the Sea of Fallen Stars covers a very large area, the greater part of it has many islands breaking the surface, arguing for being relatively shallow.  But if it is similar to the Mediterranean Sea, it may actually have a deepest point of ~3 miles.


Are the Bandwidth authorities and the Directory Authorities the same servers?

Question: Are the Bandwidth authorities and the Directory Authorities the same servers? do the same people run both? or am i posing the wrong question, is reporting on bandwidth a job that the Directory authorities perform?
Answer: A bandwidth authority is just a directory authority that also measures relays and votes about their speeds.
The code that performs the measurements is usually run by the same person as the actual tor process that is a directory authority, but it doesn't have to be.
The measurements do not have to be performed on the same machine as the tor process that is a directory authority.


How to reset or rebuild Groove Music in Windows 10 Mobile?

Question: I have removed all the files from my Lumia 640 XL and now my playlist shows a red exclamation mark for those missing files. Can someone assist me with resetting/rebuilding my Groove Music file list, just like it is when I start my mobile for the first time where it builds the playlist?
Comment: Have you tried resetting the Groove app? You can do it from within its Settings menu.
Answer: Follow these steps:

Open Settings
Click on System
Select Groove Music
Click the Advanced options link
Click the Reset button
Click Reset one more time to confirm.

Using the reset feature will delete all the app data on the device, including preferences and sign-in details.
Comment: The above steps don't work on system apps. Groove is a system app and reset button is greyed-out.
Answer: Unfortunately Microsoft removed the ability to reset Groove Music from the Settings menu.  However, you can delete everything in the Grove Music database and start over from scratch.
NOTE: These instructions assume all of your music is being stored on a microSD card. If this isn't the case you should buy a microSD (they're dirt cheap anymore, so you have no excuse) and transfer your music to it before proceeding.

Power off your phone and remove the microSD card that contains your music library.

Power up the phone, launch Groove Music, and select the "Albums" view.

Press and hold the topmost album, and when the menu pops up, select it.

Once the album is selected, tap the Menu (the three dots in the lower right corner) and "Select All" albums.  BE PATIENT!  Depending on how many albums you have it can take five to ten minutes for Groove Music to select all of them!

Tap the trash can to delete all of the selected albums.  Again, BE PATIENT! because it will take time for Groove Music to delete all of the albums.

Once all of the albums are deleted, power off your phone, reinsert the microSD card, power the phone back up, select Groove Music, and it will start reloading your music collection into the database.