I was leaning the bike against the wall

Question: I have a quite a new bike (aluminium frame) and I came home after a ride and when I was leaning a bike against the wall I hit the brake caliper (or more like the tube, that's next to it) against the wall. It was not with much of a force but I'm little bit scared if I didn't damage the brake or the caliper.
Comment: Welcome to Bicycles SE.  There are several similar questions on this subject on this site, worth investigating to see if it answers your question. Additionally, without some pictures/images there is no way to answer your question reliably.  Are we talking about a small blemish, or are the tubes of your bike frame bent?  Pictures, detailed please.  Edit your question to add them.
Answer: The bike must be able to handle such usage. And much worse. What can happen with some moderate force is moving the caliper very slightly out of alignment. Then it must be re-aligned. Out of alignment would show itself as brake rub. Bigger forces could cause it to move more and potentially deform the rotor, but that must already be some force.
If you lean the bike on the wall by the rotor itself than it could potentially be deformed. Maybe not always just by the weight of the bike itself, but I would be worried even about that. With some additional force it is certainly possible.  Try not to do that. The rotor could also become contaminated by touching other stuff.
The frame tubes must be able to withstand some beating and small falls. Otherwise the bike would be plain dangerous if it were too fragile.
Answer: Worst-case scenario, you bumped a brake component out of alignment and the only symptom will be that you hear the brake disc rubbing (in which case, have a qualified mechanic inspect the brake and replace the disc if the disc is bent). It is extremely unlikely that you did any damage that poses a safety issue when leaning the bike against a wall.
Answer: The disc brake rotor and the brake cable+housing are the most fragile parts back there. The frame tubes and the caliper should be quite strong, especially close to the rear axle.
As long as the rotor is not bent to the point where it rubs and the brake cable housing doesn't have any (deep) scratches or kinks I wouldn't worry at all.
When the bike falls over or is leaned against a flat surface the fragile parts should be protected by the frame and wheel. They are only really at risk when you hit uneven objects (e.g. falling on a small boulder).
Answer: Sounds like the seat/chain stay touched the wall rather than the caliper. If it was a controlled lean - as you say there was not much force involved - and no damage (scratches, dents) or damage symptoms (brakes scratching) are present, I don't think there is a problem. Even a light scratch in the paint doesn't mean your bike is a write-off, it's just the first scratch that hurts the most.
As explained in other answers, frames can take more than that - aluminum would bend or show visible dents, then the part may be weakened, on carbon bikes a chip of one or more carbon layers or cracks would be problematic.
This question (or this one) give some reference about actual aluminum frame damage in various levels from cosmetic to "beyond repair"/failed.
Just make sure that you lean your bike against a wall with parts don't take any damage from touching metal/concrete and the bike isn't likely to fall over the way you park it. So, it shouldn't be able to roll and at an angle towards the wall. Also consider wind, I once parked my bike on a mountain summit and the wind blew it over for a fall.
That's a good video on the topic, no need to copy and paste content from there:

I was leaning the bike against the wall


To what extent do the big boys and girls use DDM?

Question: I am wondering to which extent versions of the DDM formula(https://en.wikipedia.org/wiki/Dividend_discount_model) is used by large banks and institutional investors etc, in some sense anyone who is not a retail investor.
Answer: Dividend discount model is flawed in the format it is given in.
It requires you to enter dividend (known), growth rate for dividends (well, you could estimate that for an individual stock but your estimate could be way off because this is predicting the future which is hard) and yield demand (this is very hard to give).
Specifically, the problem is with yield demand. By slightly adjusting the yield demand, you get very wildly different valuations. It is hard to justify what is the correct yield demand for a company. It will depend, among other things, on the riskiness of the company as an investment. Riskier companies require more yield. How much more, that's hard to specify.
So, the format P = D/(r - g) is not really useful.
However, adjust the formula little and you will get r = g + D/P
What does it tell you? It tells that "total expected return equates to dividend growth plus dividend yield".
In this format, the formula is very useful, because it tells you how much stocks yield. They yield dividend growth plus dividend yield.
In a large well-diversified portfolio, the dividend growth is nominal economic growth. It is useful to split it into two constituents: inflation and real economic growth. If doing that, the formula says "total expected return from a well-diversified stock portfolio equates to inflation plus real economic growth plus dividend yield".
That, to me, is a very strong and useful result. It can be used to estimate whether stock investments make sense, and if so, to what extent. The only difficulty of using that strong result is that you need to estimate what the cyclically averaged sustainable dividend yield is at a particular point of time.
Comment: Yep, I had to carefully consider whether to post the answer. I used the "Google test", i.e. if someone is searching using Google with the term "dividend discount model", they might find this question and find my answer useful. But feel free not to upvote if it answers a different question!
Comment: Very nice answer, but it answering kind of a different question i.e "what are the caveats with DDM"?. Ill comment on your observations tho, one could consider the current market price and think of that as something that implies the two unknowns r and g. g in turn is also estimated by the market, which as you indicate above makes one being able to solve for r. hence looking at EPS estimates and the current price one could think  weather those are reasonable give what once own perception of the market is


Msvcr90d.dll not found when building in RELEASE

Question: It's strange, if I build my program in debug mode, I have no errors, but if I build my program in released mode, I get an error saying that Msvcr90d.dll is not found.
Msvcr90d.dll is a debug library, I'm not sure why it's coming up when I load it for release =/
Answer: msvcr90d.dll is a debug version of C/C++ library. It looks like you have a dependency somewhere on a debug target. Check that all the projects in release target use the release version of C runtime, and not the debug. Also, check other 3rd party libraries (DLLs) that you might use, so they not depend on msvcr90d.dll
You can use dependency walker tool to check the dependencies of your binaries, so you can identify the project in your solution that still depends on debug version of C library.
Answer: If you are getting the warning LNK 4098 during build, please see this
http://msdn.microsoft.com/en-us/library/6wtdswk0(VS.71).aspx
And follow the recommendations.
Also, make sure that you chose the correct C/C++ runtime under the Code Generation tab (Multi-threaded DLL -- not Multithreaded Debug DLL)


Files (Nautilus) icons not appearing with Numix Square icon theme on Ubuntu 18.04 LTS with Unity desktop

Question: I'm using Unity 7 on Ubuntu 18.04 LTS. I've installed and set the Numix Square icon theme and restarted Unity. Nautilus seems to still show the default empty file icon for all files and folders. It does show image thumbnails, however. Changed icons with Unity Tweak Tool.
Answer: I did not have any icon themes installed with folder and file icons so it fell back to the default empty file icon from the GNOME system theme.
Both Numix Square and Numix Circle do not have built-in system icons or file/folder icons but instead require the Numix icon theme to be installed. This fixed my particular problem!


Insert javascript into local html using its CSS stylesheet?

Question: Modifying a SnapPages theme, meaning I only have access to the CSS stylesheet. I would like to insert some javascript in the header of the site in order to use TypeKit for styling typography. Is there anyway to do that from CSS?
Answer: Simple answer: No.
More complex answer: CSS doesn't have the ability to make any changes to your page and things included in a page either via:
<code><link rel="stylesheet" type="text/css" href="custom.css" />
// or
<style>
  ..
</style>
</code>
Can't be made to execute as script.
Answer: Though you can in a sense alter (some of) the contents of a page from CSS, its use is discouraged and it is not up to the task you want to handle.
From quir]{smode:
"I feel that we shouldn't use the content declaration at all. It adds content to the page, and CSS is meant for adding presentation to the page, and not content. Therefore I feel that you should use JavaScript if you want to dynamically generate content. CSS is the wrong tool for this job."
Answer: Not to my knowledge, no.
Answer: I don't think there is, no.
The only thing coming even close is IE-Based CSS Expressions (examples here). It may even have been possible to import style sheets that way, but support was discontinued in IE8.


Import and replace existing page/post content

Question: Is there any way to import a basic, exported Wordpress content XML file and have it replace the existing content?  What I'm trying to do is synch up two instances of a site (development and staging servers) and all I want to replace is the Page content.  When I try to import the XML document it simply states that all the pages already exist and nothing is done.  Is it possible to override that warning and replace the content of the pages with the content of the XML?
Answer: One option might be to export both XML files, merge them using a file merging tool like http://winmerge.org, delete all posts and replace with the merged version.
Comment: That's not a bad idea.  Hopefully nothing will be affected by the change of post IDs.  Which there was a way to enable the importer to just overwrite existing posts.
Answer: Run A Query to Delete All Staging Posts before Importing From Dev
Because menus and pages are custom post types, this will update all posts, pages, and menus to match your dev site.

Delete all posts in the staging server by running a database query. Note that the code requires setting a userid. modify it if there are more users or run it more than once.
SET @WPUSERID='1';
-- end config
-- Delete a,b,c
   FROM wp_posts a
   LEFT JOIN wp_term_relationships b
   ON (a.ID = b.object_id)
   LEFT JOIN wp_postmeta c
   ON (a.ID = c.post_id)
   WHERE a.post_author = @WPUSERID;

Import the XML file that you exported from the Dev site.

Caution: Back up your databases for both dev and staging in case you accidently get them mixed up (you think you're connected to stage for example, and you are really connected to dev when you do the delete) .

Be safe: view posts before deleting
Select * FROM wp_posts a
LEFT JOIN wp_term_relationships b
ON (a.ID = b.object_id)
LEFT JOIN wp_postmeta c
ON (a.ID = c.post_id)
WHERE a.post_author = @WPUSERID;

Answer: In my case - I'm trying to overwrite the content two of the default pages created by sage with predefined content - the best way to overwrite the page/post content was by using the wp post update cli command.
wp post update 2 "./assets/page-content.html"

where 2 is the page ID and ./assets/page-content.html is the path to the file with the new content (you could extract the content from an exported xml if you need to).
https://developer.wordpress.org/cli/commands/post/update/


Axiom of Pairing

Question: Axiom of Pairing states that if $a,b$ are sets, $\exists$ a set $A$ such that $A=\{{a,b\}}$.But why we can't just write the set $A=\{a,b\}$ explicitly so we don't need that axiom?
Answer: Formally speaking, the fact that you can write $\{a,b\}$ doesn't mean that it exists in your model.
You can also write $\frac12$ quite explicitly, and yet it doesn't exist in $\Bbb Z$.
And similarly you can write $-1,\sqrt2$ and $\sqrt{-1}$ which don't exist in $\Bbb{N,Q,R}$ respectively.
Comment: No, you can't. Because sets are mathematical objects and wolves are not. Although strictly speaking, you can treat whatever you want however you want, it's up to other people decide if their time is worth spending listening to a madman, though. The point is that there are two parts, syntax where logic and axioms and proving things live; and semantics where actual objects "exist" (in the mathematical sense), where statements are true or false and not just provable. So given a model of set theory, in order to ensure that certain things exist we want to prove their existence from the axioms [...]
Comment: Does that mean that the originally existing set is only $\phi$
Comment: No. There is no "originally existing set". If you have a model, then it everything in that model already exists. What can you prove that exists is a whole other thing. If you don't assume the axiom of infinity, can you prove that $\omega$ exists? No, you can't, but it might exist in a given model regardless. Existence is really a semantic "property", so when you talk about things which exist you invariably talk about a model. So once a model is taken, everything inside of it exists. The question is whether or not you can prove that a given set exists (so it would exist in all models).
Comment: Sorry I couldn't get your idea, so e.x. can I treat a wolf a set?
Comment: So we need to have suitable axioms. But existence, per se, is a statement about models. So even if I gave you a model of set theory, and you know that $\{a,b\}$ exists in that model. You still want to be able and ensure that if I gave you another model, such set would exist there (given that $a,b$ are in the other model too). And this is what the axioms give you, the ability to prove that the set $\{a,b\}$ exists. And if you can prove something, then it is true in all the models of the theory.
Comment: Does that mean(not rigorous), if we already have rational number, and the axiom tells us that the limit of rational number exists,then we get irrational number?
Comment: No. And now I'm worried that I completely confused you.
Comment: Another question: Without the Axiom of Specification,we can't assume that a subset of a set exists,right?
Comment: Not in general, no. Unless we have some other means to prove that (e.g. Axiom of Replacement).
Answer: In informal proofs of the kind you see in most mathematics textbooks, the author can get away with simply writing $A=\{a,b\}$ as you suggest without having to cite any particular axiom to justify it.
In formal proofs on, say, some foundational issue, the author would have to explicitly cite the Pairing Axiom to justify $A=\{a,b\}$, the proof being a test of the system of axioms used as much as anything else.

Axiom of Pairing


proxying through corporate firewall

Question: I'm trying to get some protocols work through my company's firewall. Until now I have been succesfull in masking either http or https data by setting a http proxy on localhost and one on a remote server I own. The communication is done via $_POSTed and received modified .bmp files that contain a header and the encripted serialised request array.
This works fine, but there are a few drawbacks that make me think I might have taken a wrong approach.
Firstly I do not use apache's mod-proxy. instead I just created a local subdomain (proxy.localhost) and use that in browser's proxy settings. the subdomain's index.php does all the work. This creates some problems. I cannot use http and https simultaneously or the server will complain of using either "http on a https enabled port" or "incoresc ssl response length".
The second problem is, well, other protocols. I could make use of some ftp, sftp, remote deskoptop, ssh, nust name another... I need it
there are 2 solutions I can think of: First is if I run a php script in CLI so that it listens on a predefined port and handles the requests differently, or some sort of ssh tunnel. Problem is I haven't had any success with freeSSHd and putty because of my ignorance.
Thanks in advance for any advice.
Answer: I used the free version of bitvise SSH Client and server and it seems to work just fine.

proxying through corporate firewall


Why is finding the median and quartiles different on a cumulative frequency graph? (Or is it?)

Question: When finding the median we look for the (n+1)/2 value in the ordered data set. For the lower quartile it's the (n+1)/4 value and the upper quartile is 3/4(n+1). However, I've been helping my girlfriend with some homework where she has to find these statistics by looking at a cumulative frequency graph. Here, n=40 and she has been told to read along from 20 on the y-axis for the media, and 10 and 30 for the quartiles. In my mind, we should read along from 20.5, 10.25, and 30.75 respectively, but looking online it seems that the way she has been taught is fairly standard. Am I missing something about the way this works with the graph?
Comment: Your view is reasonable  (so you might choose the midpoint of the 20th and 21st ordered values as the median) but there are many different ways of defining quantiles.  It seems your girlfriend has been taught something simple though slightly biased.
Comment: The median is the middle entry in the sorted data set or the arithmetic mean of the two middle entries. I am not sure about the exact definition for the quartiles. Looking at the value at $20.5$ will usually give a good approximation, but we need two values to get the exact median in the case of an even number of entries.
Comment: For practical purposes, the described method should be good enough although it might occasionally be far off the true value. And it is easy to be applied and to be memorized.
Comment: These comments are very useful. I suppose I was expecting there to be one right answer and couldn't see how this method was acceptable, but I was forgetting that sometimes statistics isn't as black and white as other fields. I was really confident in telling her she must have misunderstood and I undermined her confidence. I feel terrible now!
Comment: If this is the most misleading thing you every tell her, you will be doing just fine.
Answer: The usual definition of the 25th quartile is a value $q$ such that not more than 25% of observations are below $q$ and nor more than 75% are above $q.$
Depending
on the number of observations and on the particular
observations about a quarter of the way along the
sorted data, that usual definition may result in an
interval of possible 25th quartiles.
various texts and software programs have adopted
different rules as to which value in such an
interval to select. About ten rules are in common
use, with no signs of a consensus on the horizon.
R statistical software calls the different rules
'types'; type=7 is the default, but the user
can supply an argument to choose any of the others.
Suppose you have 40 observations from $\mathsf{Norm}(\mu=100,\sigma=15).$ The population lower and upper quartiles are about 89.9 and 110,1, as shown below.
qnorm(c(.25,.75), 100, 15)
[1]  89.88265 110.11735

Quartiles of a particular sample of size $n = 40$
from this distribution (rounded to two places) will
be "near" these population quartiles, but
results will differ as to type.
set.seed(2022)
x = round(rnorm(40, 100, 15), 2);  sort(x)

 [1]  56.49  76.62  78.33  82.40  84.11  85.27  85.74  86.54  87.11  87.74
[11]  90.19  92.23  94.78  95.03  96.42  96.69  97.22  97.47  98.80  99.21
[21] 101.39 101.77 102.13 102.35 103.62 104.17 104.92 105.47 105.75 109.75
[31] 111.24 112.47 112.89 113.50 115.09 115.29 116.15 116.19 116.70 118.17

Here are some results (look under 25% for lower quantiles).
These are various ways to put a number into the gap between the end of
the first line $87.74$ and the beginning of the second line $90.19$ above.
quantile(x)  # default 'type 7'
      0%      25%      50%      75%     100%
 56.4900  89.5775 100.3000 110.1225 118.1700
quantile(x, type=1)
    0%    25%    50%    75%   100%
 56.49  87.74  99.21 109.75 118.17
quantile(x, type=2)
     0%     25%     50%     75%    100%
 56.490  88.965 100.300 110.495 118.170
quantile(x, type=3)
    0%    25%    50%    75%   100%
 56.49  87.74  99.21 109.75 118.17
quantile(x, type=4)
    0%    25%    50%    75%   100%
 56.49  87.74  99.21 109.75 118.17
quantile(x, type=5)
     0%     25%     50%     75%    100%
 56.490  88.965 100.300 110.495 118.170
 quantile(x, type=6)
      0%      25%      50%      75%     100%
 56.4900  88.3525 100.3000 110.8675 118.1700

Below is an empirical CDF plot (ECDF) of the sample.
The horizontal red line is at .25 on the vertical
asis. It intersects the ECDF at a flat spot, corresponding
to various choices of the 25th percentile. (lower quartile).
plot(ecdf(x))
 abline(h=.25, col="red")

For your girlfriend's class, it is best to use whatever
rule the text or her class notes specifies. Otherwise,
you are free to choose any 'type' of 25th percentile you
like.
In practice quartiles and other percentiles are most
commonly used for large samples, where differences in
'types' often make no practical difference.


1 John 2:19b - What might become plain, the origin? The state? Or the origin and original state of "they?

Question: 1 John 2:19 - They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us.(YTL)
Answer: When the apostle John wrote his first epistle, it was likely after he'd written his gospel account, due to the epistle building on concepts and themes he had explained at length there. In this epistle, these things are taken as understood. Confirming this is the way a form of Gnosticism prevalent near the end of the first century is inferred in the epistle. According to these notes, we can see what had become plain:

"The Gnosticism addressed in the NT was an early form of the heresy,
not the intricately developed teaching of the Cerinthian variety. This
heresy was also libertine, throwing off all moral restraint.
Consequently, John wrote this letter with two basic purposes in mind:
(1) to expose false teachers (2:26) and (2) to give believers
assurance of salvation (5:13). In keeping with his intention to combat
Gnostic teachers, John specifically struck at their total lack of
morality (3:8-10)..." NIV Study Bible, 1987 Ed., p 1866

Now, with this background in mind, what does the text in question make plain? First the text is dealing with particular people. It is making something plain about specific people who had been involved with the first century Christian Church.
Is John making plain the original state of 'they' [these people] (you ask), or the [present] state of these people (is what I infer), or both of those things? John's language was plain enough for his readers. They knew who those people were, for those people had mixed with them but now had left them. In the previous verse, 18, John had identified them as being 'antichrist' (plural). He spoke of them as being 'many'.

"John assumed his readers knew that a great enemy of God and his
people will arise before Christ's return... But prior to him will be
many antichrists... The antichrists referred to in John's letter were
the early Gnostics. The 'anti' in antichrist means 'against' [or, 'in
the place of'.]" (Ibid. p 1869)

John does not say anything about the origins of Gnosticism. He does not show the origins of it. He simply takes the fact of Gnostics having come into the Church by the time he wrote that warning, but of having then left the Church: "They went out from us, but they did not really belong to us." (NIV) That is what had become plain.


Stacked ensemble model characteristics

Question: In which areas/ problems stacked ensemble is useful compared to other models in a specific industry/ application. Commonly, either simple model such as linear regression is utilized for explanaibility while black-box models such as neural network were used in different cases. Where does stacked ensemble models stand?
Answer: To my knowledge there's no specific use-case for stacked ensemble models.

There are technical constraints: by definition these models require training multiple individual models so the training must not be too intensive (e.g. one rarely use it with DL models which need very long training).
There are some advantages in terms of performance and especially of stability/reliability of the results, since these models are statistically more robust to noise (i.e. less likely to ovefit).

From the point of view of explainability, ensemble models tend to be complex to explain since the explanation of a prediction involves multiple individual models. So it can be doable but it's not convenient at all.

Stacked ensemble model characteristics


Relation between worldsheets and worldlines

Question: If we want to find the propagator of say a zero-spin particle, the formal inverse can be computed by introducing $$-i\int_{0}^{\infty}e^{i(p^2 - m^2)s}\mathrm{d}s$$ We can rewrite this in path integral form as well. Is this somehow generalised by the introduction of a worldsheet action? If so, then is there an analogue of the Schwinger proper time formalism in string theory?
Comment: Yes, the Schwinger proper time formalism applies to both point mechanics, field theory and string theory.
Answer: There is a world-sheet formalism generalizing the worldline formalism. In this formalism, in the Feynman diagrams:

The integration over the light cone coordinate $p_{-} = \frac{1}{\sqrt{2}}(p_0 - p_3)$ is traded by an integration on $x^{+} = \frac{1}{\sqrt{2}}(x^0 + x^3)$  by means of a Fourier transform.
Then, the  integration on the lightcone $p_{+} = \frac{1}{\sqrt{2}}(p_0 + p_3)$ and $x^{+} $ coordinates is separated from the other integration in the Feynman diagrams and treated as an integration over a world-sheet. Please, see the following works by Thorn and  Bardakci first  and second  and references therein.

The idea can be illustrated on a scalar massless propagator , whose expression in the mixed lightcone coordinates is given by:
$$\Delta(\mathbf{p}, p_{+}, x^{+}) = \langle \phi(\mathbb{p}, p_{+}, x^{+}) ) \phi(0)\rangle = \int \frac{dp_{-}}{2 \pi i } e^{-i p_{-}x^{+}} \frac{1}{p^2-i \epsilon} = \frac{\theta(x^{+})}{2 p_{-}} e^{\frac{x^{+} \mathbf{p}^2}{2 p_{+}}}$$
where $\mathbf{p}$ is the vector of the rest of the coordinates (of dimension $d-2$  where $d$ is the dimension of space time).
Bardakci  and Thorn found a string worldsheet path integral representation of the above propagator as:
$$\Delta(\mathbf{p}, p_{+}, x^{+}) = \int \mathcal{Dc}\mathcal{Dc}\mathcal{Dq} e^{-S}$$
with
$$ S = \int_0^{x^{+}} \int_0^{p_{+}} d\sigma  \left ( \frac{1}{2}\mathbb{q}'^2 - b'c'  \right)$$
Where $\mathbf{q}$ is a $d-2$ dimensional vector and $b$ and $c$ are Grasmann vector of half of the dimension of $\mathbf{q}$.
The boundary condition for $b$ and $c$ are $0$ on all the worldsheet boundaries and for $\mathbf{q}$ , we have
$$\mathbb{q}(p_{+}, \tau) - \mathbb{q}(0, \tau) =  \mathbf{p}$$
The above technique can be applied by means of inserting the above expressions for the propagators in the Feynman diagrams and use lightcone expressions for the vertices.
This formalism is useful in dealing with Yang-Mills theoies with large number colors,  where the semiclassical contribution of the worldsheet integrals dominate, because the number of colors will appear multiplicatively in the worldsheet actions.
This formalism is a realization of 't Hooft idea of the  dominance of the planar diagrams in the large color limit and provides in principle a method for summing these diagrams.


Samsung galaxy S4 not charging

Question: One day my Samsung stopped charging, as to my battery was swelling up. The following day I bought a new battery and it is still giving me the same problem. It does not charge or show any sign that it is working. Does anyone know a solution? I've tried many that I've viewed on youtube, but still doesn't work.
Comment: Consider changing your battery for your safety perpuse and dispose battery with care.
Comment: it's explosion protection that kicked in
Comment: @VivekJi they had already replaced the swollen battery
Comment: @SargeBorsch Haven't heard of explosion protection. Kindly expound on it.
Answer:
Battery swelling up is an indication of battery in terminal stages . It's good that you decided to replace with a new battery
If the new battery is not charging, possible reasons:

a) It could be a rip off battery
b) battery charging is prevented by a transparent plastic foil on the terminals which is preventing contact. Examine carefully and peel it off . See this for a similar issue with S3 batteries
Phone only works with busted battery
C) there is a genuine problem with hardware
First eliminate b) then check for a) by borrowing a battery and if both are ruled out, your problem is C) for which only service center can fix
Answer: Your USB port maybe damaged. It's very cheap and easy to replace. I did on mine after the phone had trouble charging, and it worked great afterwards.

Samsung galaxy S4 not charging


Tax implications for sending and receiving money from India

Question: I am planning to send $40000 to my friend in India. After few months, he plans to return me the same amount.
What would be the tax implications for both of us in India and USA?
Thanks in advance!
Comment: How well do you know your friend in India? Why do they need the money? How do you know that they will actually return the money? I realize that this is not directly relevant to "tax implications", but we see a lot of [scams](https://money.stackexchange.com/questions/tagged/scams) on this site, so I hope you will forgive me for being suspicious.
Comment: In addition to other points, from April India will impose a TDS on foreign remittances https://economictimes.indiatimes.com/news/economy/policy/remittance-tax-as-i-t-survey-shows-non-filing-of-returns/articleshow/74126772.cms
Answer: There are no tax implications in the US provided that you execute a proper loan agreement with your friend (and both you and he keep a copy of this document with your tax papers). The loan document should spell out the repayment terms (when is the loan due?) and what reasonable (as per what IRS deems reasonable) interest rate will be charged on the loan. The interest that you "receive" from this friend must be declared as income on your US tax return. The word "received_ is in quotes because it is common among friends to actually charge no interest at all (and perhaps even set no fixed date for repayment (or repayment in installments)) and in such a case, the lender must nonetheless record the interest (per loan agreement) as taxable income to himself even though no money actually changes hands. The lender has, in effect, made a gift of the interest amount to the borrower, and with a loan of US $40K, the gift is small enough that the lender is not liable for gift tax.
For the borrower, having the paperwork spelling out that this is a loan is helpful in avoiding taxation in India, and makes life easier for him when it is time to return the money. There is no tax on the loan proceeds -- they are not income to the borrower -- and when it is time to repay, there is legitimate cause for requesting foreign exchange the tune of US $40K. Of course, for all this to work, the money must be sent openly through normal banking channels (including such services as TransferWise or Xoom or Remit2India etc) and not via the Havala market.
Answer: He plans to give back it to you. So, receiver need to mention this amount as borrowed in accounts and income tax return. And he need to declare this  to bank, if bank needs FEMA declaration, before fund credit.
When he give back to you, he need to mention the source of fund to repay that. That would be taxable.
I don't know US part.


Could Azog possibly have been under Sauron's influence?

Question: In the books, I can't remember what year it was, but Sauron sent orcs and other creatures to Moria, and then a couple hundred years after, Azog declared himself king of Moria.  I think it's possible Sauron may have chosen an orc chieftain or champion to rule Moria.  Is there any evidence to support or refute this?
Answer: I don't think there's any evidence that specifically support or refutes this. In the books, Azog was killed in 2799 of the Third Age, and Sauron had been relatively active (for a disembodied spirit of malevolence, at least) in Dol Guldur for a while by then.
I can't say whether or not Sauron personally put Azog in charge (That seems like the kind of minutiae that a god wouldn't get involved with), but Azog was almost certainly working for Sauron at this time. It seems extremely likely that Azog's killing of Thror (which kicked off the Battle of Azanulbizar in the books, rather than taking place during it as the movie shows), was motivated by Sauron's desire to possess the ring of power that he would later acquire from Thrain, Thror's son and Thorin's father.
Comment: Sauron may have been in charge of the big picture, but Azog was in charge of Moria. Azog probably called himself "king" partly to irritate the dwarves, and partly because orcs don't have a very complicated social structure. Sauron probably didn't care what Azog called himself; seeing orcs as slave creatures, he would only have cared that they served him
Comment: Tale of Years for TA 2480: "Sauron begins to people Moria with his creatures".
Comment: I do think azog may have killed thror on saurons orders it would make sense in my opinion but then again why would azog declare himself king of moria if he was saurons servant?
Comment: Also, if Azog didn't die during the war of the Dwarves and Orcs leaving the denizens of the Mines of Moria leaderless then they would have been organized enough to heed Sauron's call and would have sent forces to Mordor.  Remember that it wasn't until TA 2800 that the Orcs of the North started migrating to Mordor through Rohan.
Comment: The Tale of Years says that "Orcs from the North trouble Rohan" starting in T.A. 2800. There's no mention of it them doing so *en route* to Mordor, though. A comment in the entry for Brytta in the list of the Kings of the Mark only mentions that the Orcs, being driven from the North (presumably by the Dwarves) are seeking refuge in the White Mountains.


Why are global phases neglected in the check matrix representation of stabilizers?

Question: In the check matrix representation of stabilizers, one does not care about the global phase. Now why is that?
As far as I understand if I have a quantum computation, it can be computationally more efficient to keep track of how the stabilizers transform to find the unique quantum state they stabilize in the end (result of our quantum computation), rather than doing the calculation and keeping track of how the state transforms in each step. Now when neglceting the global phase would that still be possible?
For example, suppose we have $X_1 X_2$ and $Z_1 Z_2$, they stabilize the unique state $\phi^+$. On the other hand, if we have $-X_1 X_2$ and $Z_1 Z_2$, they stabilize $\phi^-$ (I don't know whether this is the unique state). So as we can see, the global phase of our operators does have an impact on which state is stabilized. Or maybe I haven't quite understood the usage of the stabilizer formalism yet.
Answer: The sign on the stabilizers is not what people mean by "global phase". For example, the state stabilized by $+Z$ is $|0\rangle$ and the state stabilized by $-Z$ is $|1\rangle$. These states differ by more than just global phase.
The global phase issue is that $+Z$ stabilizes $|0\rangle$ and also $-|0\rangle$ and also $i|0\rangle$ and more generally any state of the form $e^{i \theta} |0\rangle$. Given only the stabilizers, you can't tell what the value of $\theta$ is supposed to be. In most contexts this isn't an issue, but it's a problem if (for example) you are approximating a non-Clifford state as a linear combination of stabilizer states. The different terms of that linear combination need to have the correct phases in order for the sum to come out right.


Should I avoid using javascript and jquery in my website?

Question: I use some jquery and JS functions to validate forms and to check for example if that field is empty or password is less than 6 characters, and stuff like that, and I noticed that if someone disabled JS, then these functions would be useless, and no more protection of forms, which can be better made using PHP, so should I avoid them now because this could cause an insult to my website ?
Comment: possible duplicate of [JavaScript: client-side vs. server-side validation](http://stackoverflow.com/questions/162159/javascript-client-side-vs-server-side-validation)
Comment: JS validating of forms on client-side isn't sufficient. You should also check the value sent by the client to the server on server-side. For this is the appropriate php for example.
Answer: JavaScript is very useful for improving user-interaction, along with reducing the number of requests made on the server; but, as you've pointed out, it can be disabled. To answer your question: No, I wouldn't recommend avoiding the use of JavaScript, but the key is not to rely on it for critical actions, such as validation. You'll want to implement the validation on both the client (JavaScript) and server (PHP) sides. This will ensure that there is no way for the user to completely disable the validation.
In short:

JavaScript = Good
JavaScript Validation = Nice for the user, but not reliable
Server Side Validation = Essential

Side note:
With regards to relying on JavaScript for the overall user interaction, as other answers have suggested, use JavaScript to enhance the overall experience, but don't rely on the user having it turned on. I would recommend a bit of bed time reading of Progressive Enhancement, it's the approach of making something better, with being reliant on it, and can be applied to more than just JavaScript (CSS3 etc).
Comment: Do you mean 'server side validation = essential'?
Answer: You should use javascript and jQuery to enhance the functionality of your site. If someone has javascript turned off you should ensure that the site still works, and they can access all areas - even though there may be some things they cannot see, such as transitions and effects.
With regard to validation, you should ALWAYS validate server side. Client side validation is optional, but a very nice feature to improve the user experience for your visitors.
Comment: If you are relying on javascript for your UI then you either need to rethink your approach, or have a message displayed in an obvious position on the website which explains that javascript is required for your website to function correctly.
Comment: But my website depends a lot on .fadeIn() and .fadeOut(), with JS disabled, these functions wont work, and lots of contents, they wont be able to reach them
Comment: I used  to display a message, and everything else is hidden, when document is loaded everything else will show up, this is a good protection if someone is accessing it now with JS disabled, but bad protection when someone goes to my website, and THEN disables it.
Answer: I don't mean this as a complaint, more of an observation.
Web developers often grab Javascript libraries as the latest shiny toys with no thought for the consequences. As a Data Governance person, I'm regularly the bringer of bad news, when we do audits on the data collected, and find users who get past the Javascript validation.
"Go back and start again".
Javascript libraries are great for the presentation of data, but should and must not be relied on for data validation and the integrity of user profiles.
Answer: You should not avoid using JS and jQuery in your website, but you should avoid using them for validation purposes or business-logic purposes. These should be done in the back-end of the website, not in the UI level.
Answer: A validation should always happen at

Client Side - using javascript to enhance the user experience.
Server Side - using the preferred server side programming language for security reasons
Service Side - if you are following SOA / Web API as part of defensive programming practice. This can also be at the DB level along with Service layer.
Answer: You shouldn't really avoid them. What you should do is to implement both client and server validation. Don't rely just on client validation, for the reasons you just mentioned. You should always validate the data when it arrives to server.
Adding client-side validation gives your pages dynamic look and feel. A user does not have to wait for the form to go to server and in case of an error to return back. It is automatically verified without postback.
As I said above, don't rely upon client side validation. Always implement server-side validation also.
Answer: Remember my friend, Java script is client side scripting. its purpose to validate form at client side itself so we can avoid overhead...You must use java script at client side. because PHp is server side language. It will take time to reply.
Ha, Server Side validations are equally important. if you want to do that, then you can use server side language. You can check comment below to my post by halfer. Server side validations are important for security and many more purposes.
That is different thing that somebody disabled js. You can check for the same and give proper message to enable.
Comment: Might be an idea to edit your post then, so it is clear `:)`.
Comment: No, don't use "java script only" - that would be a recommendation to avoid server-side validation, which would leave you open to security risks, database errors, fatal script errors etc.
Comment: @halfer-I was talking about client side validation...i really appreciate for your comment..server side validations are equally important.


What counters a jungle Olaf?

Question: If you've ever been against a good jungle Olaf, you probably know how devastating he can be... his clear speed is insane with blue and his ganks are annoyingly strong if he lands his first Q, which if you go too far to dodge you'll be worse off than having been hit. So... what are some ways to counter him? As a mid laner? As a jungler?
Comment: Olaf's ganks are amongst the weakest in the game (a short-medium ranged skillshot, based slow is hardly scary). Out of curiosity what elo are you?
Answer: He simply is strong. Its like saying "what counters a shyvana jungle". well... nothing. His ganks are strong. Ward correctly and push out (its really hard to gank for a olaf if the lane is pushed, cause if he comes form behind and throws a axe, he has to run past you to pick it up -> easy escape), or alternativly freeze the lane as long as possible, since Olaf is strongest in the early- mid game phase (first 4-5 lvls). Dont invade, he will destroy you. As mid or jungler, ward your own jungle entrances, if he trys to counterjungle get him with 3-4 people. Since most Olafs take Ghost, he is actually fairly easy to kill if you "find" him in your jungle, since he cant just flash over a wall. If you know the enemy is jungling Olaf in champ select, pick Champs that have early escape or high mobility champs in general (Ahri, Gragas, Galio for mid, Shyvana, Lee Sin, Noc for jungle) and just avoid fighting him in the early lvls.
EDIT: Jungle Olaf is REALLY blue dependend. Means after lvl 7, he is not that big of an problem anymore. If you have a really really strong lvl 1 setup, you can invade and get his blue, resulting in him beeing weaker through the rest of the game. Dont try this if your lvl 1 isnt really good, cause Olaf himself is a beast lvl 1, spammable, 2 sec cd aoe nuke with his Axe will win him nearly every lvl 1 fight.
Comment: Thanks for so much info but the baseline is that he's still hard to deal with... It's difficult in most cases to determine if hes going jungle in champ select, if he counter jungles in early stages, it's almost impossible to corner him due to his fast clear speed and the ghost that most people take, and I've seen some nasty comps with kennen or vlad mid which means olaf gets blue everytime :(
Comment: Yeah it is difficult to deal with a good jungle Olaf, but Olaf is a high skill cap champ cause his dmg and his cc are based on a skillshot. I personally think, that Irelia is way stronger for instance (top lane ofc), simply cause you dont need skill to play Irelia and she still is VERY very powerfull... if you want to play a weak jungler (Nautilus e.g.) just bann Olaf.
Answer: How to counter Olaf Top?
tl;dr - Very hard/Impossible
It depends from his summoner spells. If he has Ghost this means that he is unable to dodge your poke damage - focus on building that. If he has Flash he can't chase you down with Ragnarok - rush boots and laught at him trying land his Q.
But general tips is buy early boots and take great ranged poke champ... if it fails be ready for line swap with bot.

Boots make able you to easier dodge his Q - only CC skill that he has.  Without this slow you should be able to run away and control fight. After few missed ones especially at early game Olaf should start be more conservative about using his abilities.
Generally speaking everything that can harass or poke him in the lane is good. Most viable counter picks are Teemo with his great poke is allways viable anti brusier pick or Yorick that is designed to be hard AD Brusier counter or Nidalee that is impossible to catch.
Swap lines and make him run with poke damage dealt by your AD Carry. If AD Carry has good escape mechanism (Ezreal, Corky) he will not win after lane.

How to counter Olaf Jungle?
tl;dr - Not so scary if played properly
In general - your jungler must be better than Olaf making him "babysit" one of lines.

Wards. He is not invisible so if you play on top ward place from 2-3 minute and after all your wards expire polite ask your jungler to help you with this task. If you are playing bot - this is a task for support. If you are mid you shouldn't be afraid so much - but have in mind that your CC doesn't work on him and do not blindly trust in this. I saw Ryze who think that his rune prison will make him safe. Nope.
Boots as I explained it earlier. Mobility is key to counter Olaf IMO in all lanes. This is important for AP Casters on mid that now, in preseson 3, buy boots after 2 or 3 items. You can't do that this time!
Control his first 1-3 blue buffs. Jungle Olaf without blue is weak in early game. In mid game he don't need it so much but Olaf without assists or kills will be weak part of your enemy team.
It is dangerous to go alone against Olaf with 2 gigant belts. Build Blade of the Ruined King if you are AD - Your attacks deal 4% of the target's current health in physical damage and heals you for half the amount. This will hurt Olaf.

Good luck!
Answer: WARDS! I don't beleive that he's a good ganker because he only has a slow, and unlike Shyvanna or Mundo he can't run exhaust. Just ward enemy wraiths and ask your jungler to ward the other side on the river. He can't gank from the lane. If you still fear him, then get a mid lane with an escape: Kennen, Fizz. these two are almost impossible to gank if played smart.
Comment: his ganks are ridiculous... well if coming from the right angle, the least he will do is make you waste flash or cc(pre-6) or a disposition spell(if you have any)
Answer: There are a few things that can fight a double buffed olaf. Lee sin is pretty good if you're planning to invade. The most important thing to do if you want to shut Olaf down, but this is more of a general tip, is to deny them their buff camps and or kill them at their buff camps. Olaf is vulnerable to this because he tends to be very low in the jungle. Something like Shyvana or Lee Sin is what I would invade with, and kill him at his red. As a mid laner, Morgana, Ahri, generally anything that has some method of escaping his ganks. Olaf hates being kited.
Answer: Very good counter olaf is Jarvan (if we talk about jungle).
he can escape very easily from Olaf's axe + he does good dmg and his ulti is very good.
Mid Olaf? Never seen that :)

What counters a jungle Olaf?


Why am i not getting depth of field in my picture

Question: I cannot figure out why I am not getting a blurry background. I have the f stops all the way down. I have the distance set on my object. If I set the focus object to my object, Everything goes blurry with no focus. I have tried to scale up my whole scene as much as I could and still no blurry background. Does anyone know something else i could try.
video
Answer: Depth of Field is a camera effect.  When you turn your view in this video you're no longer looking through the camera, so it won't be present.
F-stop is the value that mainly controls the strength of the effect, but it's also dependent on things like focal length and distance to the object, and this can make overall scene scale important.
Model to real life scale and use realistic values in your camera and you should get a plausible result.  Figure out what size of a print that picture should be.  Your camera in that situation would be a literal camera with a sensor size and a lens with an actual focal length and an f value somewhere between 1.4 and let's say 16.
Recommend first that you start a new scene and play around with the camera and a couple of cubes to gain a better understanding before making drastic changes to this scene you've worked hard on.
Comment: im talking about no depth of field in the camera. I knew that there is no depth of field in the viewer. I was just moving around to show you guys the distance between the objects.
Comment: why is there no depth of field in the camera?
Comment: The back picture looks blurry in the first second of the video, but not as blurry as it should given these settings.  It should be practically a smear of fleshtone.  I'm not sure, that's why I recommend trying to recreate the scenario in a new file just as a sanity check.
Comment: @RickyBascom - Does this answer solved your issue?
Answer: @AllenSimpson is correct ... here just an example ...

Note: I used Cycles engine ...

For Eevee just switch to Eevee is blurred all, so some adjustment is needed...

I had to set bigger distance between objects to get effect ... so probably some limits to keep it real time ... and mainly enable under Scene Properties > Depth of Field enable Jitter Camera


Installing Kali Linux dual boot Windows 8

Question: I have Windows 8 currently installed on my computer I created a 350gb partition. I removed secure boot and enabled legacy boot sources, I booted into a live environment, installed Kali, everything went smooth and flawless, it prompted me that the next time I reboot it will show the Grub boot loader so I reboot and it doesn't show the boot loader. Is there something I did wrong? I asked someone what they thought and he said I didn't install grub on the MBR, I installed it on the partition itself, but I followed the tutorial on this link http://docs.kali.org/installation/dual-boot-kali-with-windows
Answer: Maybe the boot loader is not installed properly during Kali Linux installation. Download the boot loader (i.e. grub-pc) from a network mirror in Kali.
Now, boot Kali from a live boot CD/Flash Drive, then run the following commands:

In Terminal, type:  sudo fdisk -l

The partition which has Linux under System column is your drive in which Ubuntu Linux is installed. For example, Ubuntu partition drive is '/dev/sda11'

Type:  sudo mount /dev/sdXX /mnt
Mount the virtual filesystems:
<code>  sudo mount --bind /dev /mnt/dev
  sudo mount --bind /proc /mnt/proc
  sudo mount --bind /sys /mnt/sys
</code>
Type:  sudo mount --bind /usr/ /mnt/usr    and    sudo chroot /mnt
If there is no '/boot/grub/grub.cfg' or it's not correct, create one using              commands:   update-grub    or    update-grub2
Now reinstall by typing:    grub-install /dev/sdX
Type:    sudo grub-install --recheck /dev/sdX    to verify the installation.
Now press Ctrl+D to exit chrooted environment.
Unmount the mounted file systems:
  sudo umount /mnt/dev
  sudo umount /mnt/proc
  sudo umount /mnt/sys
Reboot the system

After reboot, you should be able to see the grub boot loader.
-Cheers


Graduate school needs my masters grade but I have no grades yet!

Question: I've started my graduate school applications for the next year. When I try to provide my university information I fill in a form with my grades. Since I am doing an Msc course this year I have not yet received any grades. I can't follow through the application without them though. Should I just insert 0 and explain that later?
Comment: Can you insert text? E.g. 'not available yet'?
Comment: Every university will have its own policy. Look at the admissions pages or contact their admissions staff to see what you should do.
Answer: The best way to do this would be to insert "n/a" into the field for your grades, or simply write "not available yet" as CaptainEmacs suggested. In the event that you cannot write a non-numerical answer (as was the case when I applied to grad school), a "0" should suffice that it is not your actual grade. Your application will likely require preliminary transcripts (and eventually official transcripts), so I would not worry about not being able to report your official grade, especially since this is a common problem.
I would avoid writing this issue into your statement of purpose, since your SoP should be relatively short and to the point, focusing on your research and other accomplishments. While I would definitely include your MSc course in your statement, I would not mention anything relating to the application itself. Often universities have a graduate coordinator for any given department, so I suggest reaching out to them if you have questions about your application.
Answer: You should definitely explain your situation in your personal letter/CV that you are currently taking a master's course, and provide some details on what classes you're taking. This helps giving some insight into what you're doing even though you don't have any grades yet. Sometimes universities can ask for preliminary grades, so it is best to contact the graduate admissions officer and ask for details, especially since it can vary between universities.
Comment: Thanks! I actually just insert 0 and explain it in my SoP.
Answer: I think the safest and most reasonable thing that you could do is to make a phone call to the department that you are applying to as soon as possible and inform them of your situation. They will tend to have an answer because of the volume of applications they have taken in over the years, odds are, they've come across "you" more than a handful of times.


Magnetic field due to a single moving charge

Question: The Biot-Savart law can only be used in the case of magnetostatics (constant current) so how do we calculate the magnetic field of a single charge moving at constant velocity at a distance r. I tried by calculating the displacement current
using but i was not sure wether the biot savart law can be applied to displacement currents.
Please don't use relativity if possible because i have no experience with relativity yet.
Comment: use $idl = qdv$
Answer:
A point charge $\:q\:$ is moving uniformly on a straight line with velocity  $\:\boldsymbol{\upsilon}\:$ as is the Figure. The electromagnetic field at a point $\:\mathrm{P}\:$ with position vector $\:\mathbf{x}\:$ at time $\:t\:$ is
\begin{align}
\mathbf{E}_{_{\mathbf{LW}}}\left(\mathbf{x},t\right) & \boldsymbol{=}\dfrac{q}{4\pi \epsilon_{\bf 0}}\dfrac{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\right)}{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\sin^{\bf 2}\!\phi\right)^{\boldsymbol{3/2}}}\dfrac{\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{\bf 3}},\quad \beta\boldsymbol{=}\dfrac{\upsilon}{c}
\tag{01a}\\
\mathbf{B}_{_{\mathbf{LW}}}\left(\mathbf{x},t\right) & \boldsymbol{=}\dfrac{1}{c^{ \bf 2}}\left(\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{E}\right)\vphantom{\dfrac{a}{\dfrac{}{}b}}\boldsymbol{=}\dfrac{\mu_{0}q}{4\pi }\dfrac{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\right)}{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\sin^{\bf 2}\!\phi\right)^{\boldsymbol{3/2}}}\dfrac{\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{\bf 3}}
\tag{01b}
\end{align}
Equations (01) are relativistic. They come from the Lienard-Wiechert potentials.

Biot-Savart Law

After a quick calculation with Biot-Savart Law (using the Dirac $\:\delta\:$ function) I found the solution
\begin{equation}
\mathbf{B}_{_{\mathbf{BS}}}\left(\mathbf{x},t\right) \boldsymbol{=}\dfrac{\mu_{0}q}{4\pi }\dfrac{\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{\bf 3}}
\tag{02}
\end{equation}
which compared with that from the Lienard-Wiechert potentials, see above equation (01b)
\begin{equation}
\mathbf{B}_{_{\mathbf{LW}}}\left(\mathbf{x},t\right)\boldsymbol{=}\dfrac{\mu_{0}q}{4\pi }\dfrac{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\right)}{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\sin^{\bf 2}\!\phi\right)^{\boldsymbol{3/2}}}\dfrac{\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{\bf 3}}
\tag{03}
\end{equation}
it looks as an approximation for charges whose velocities are small compared to that of light $\:c$
\begin{equation}
\mathbf{B}_{_{\mathbf{BS}}}\left(\mathbf{x},t\right)\boldsymbol{=}
\lim_{\beta \boldsymbol{\rightarrow} 0}\mathbf{B}_{_{\mathbf{LW}}}\left(\mathbf{x},t\right)\boldsymbol{=}
\lim_{\beta\boldsymbol{\rightarrow} 0}\left[\dfrac{\mu_{0}q}{4\pi }\dfrac{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\right)}{\left(1\!\boldsymbol{-}\!\beta^{\bf 2}\sin^{\bf 2}\!\phi\right)^{\boldsymbol{3/2}}}\dfrac{\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{\bf 3}}\right]\boldsymbol{=}\dfrac{\mu_{0}q}{4\pi}\dfrac{\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{3}}
\tag{04}
\end{equation}

(1)
EDIT
Answer to OP's comment :

how did you get equation 02 when v << c. – DHYEY Jun 29 '18 at 11:49

From Jackson's : Biot and Savart Law
\begin{equation}
\mathrm d\mathbf{B}=\dfrac{\mu_{0}}{4\pi}I\dfrac{\left(\mathrm d\boldsymbol{\ell}\boldsymbol{\times}\mathbf{r'}\right)}{\:\:\Vert\mathbf{r'}\Vert^{3}}
\tag{BS-01}
\end{equation}
\begin{equation}
I=q\upsilon\delta\left(x'-r\cos\phi\right), \qquad \mathrm d\boldsymbol{\ell}=\mathbf{i}\mathrm dx', \qquad \mathbf{r'}=x'\mathbf{i}\boldsymbol{+}\alpha\mathbf{j}\boldsymbol{+}0\mathbf{k}
\tag{BS-02}
\end{equation}
\begin{equation}
\mathrm d\mathbf{B}=\dfrac{\mu_{0}q}{4\pi}q\upsilon\delta\left(x'\!\boldsymbol{-}\!r\cos\phi\right)\dfrac{\left(\mathbf{i}\boldsymbol{\times}\mathbf{r'}\right)}{\:\:\Vert\mathbf{r'}\Vert^{3}}\mathrm dx'=\dfrac{\mu_{0}q}{4\pi}q\upsilon\delta\left(x'\!\boldsymbol{-}\!r\cos\phi\right)\dfrac{\left(\alpha\mathbf{k}\right)}{\:\:\left(x'^2\!\boldsymbol{+}\!\alpha^2 \right)^{3/2}}\mathrm dx'
\tag{BS-03}
\end{equation}
\begin{equation}
\mathbf{B}=\dfrac{\mu_{0}}{4\pi}q\upsilon\alpha\mathbf{k}\int\limits_{\boldsymbol{-}\boldsymbol{\infty}}^{\boldsymbol{+}\boldsymbol{\infty}}\dfrac{\delta\left(x'\!\boldsymbol{-}\!r\cos\phi\right)}{\:\:\left(x'^2\!\boldsymbol{+}\!\alpha^2 \right)^{3/2}}\mathrm dx'=\dfrac{\mu_{0}q}{4\pi}\dfrac{\upsilon\alpha\mathbf{k}}{\:\:\left(r^2\cos^2\phi\!\boldsymbol{+}\!\alpha^2 \right)^{3/2}}= \dfrac{\mu_{0}q}{4\pi}\dfrac{\left(\upsilon\mathbf{i}\right)\boldsymbol{\times}\left(\alpha\mathbf{j}\right)}{\:\:\left(r^2\cos^2\phi\!\boldsymbol{+}\!\alpha^2 \right)^{3/2}}
\tag{BS-04}
\end{equation}
\begin{equation}
\mathbf{B} =\dfrac{\mu_{0}q}{4\pi }\dfrac{\boldsymbol{\upsilon}\boldsymbol{\times}\mathbf{{r}}}{\:\:\Vert\mathbf{r}\Vert^{3}}
\tag{BS-05}
\end{equation}
Comment: how did you get equation 02 when v << c.
Comment: Why on Earth would you use bold symbol for things like the equals sign and cross product? And mix in the deprecated \bf with \mathbf? That's just weird
Comment: but finding magnetic field due to single moving charge using biot savart law(which is applicable for curent) should be wrong since its the avg current ehich we can determine for a single charge ? where is the argument wrong?
Comment: @Ashish Kumar : In "Jackson's : Biot and Savart Law" read the paragraph beginning with *"A word of caution about (5.4)..."*. Equation (5.4) therein is equation (BS-01) in my answer.
Answer: Actually there is only a slight modification in the form of the potential otherwise its the same.
The magnetic vector potential gets modified to $$
\mathbf{A}(\mathbf{r}, t) = \frac{\mu_0}{4\pi} \int \frac{\mathbf{J}(\mathbf{r}', t_r')}{|\mathbf{r} - \mathbf{r}'|} d^3\mathbf{r}$$
where $$t_r' = t - \frac{1}{c}|\mathbf{r} - \mathbf{r}'|$$
is the retarded time.
There is no relativity in here but causality is only taken into account.
Calculating the magnetic fields is a bit more difficult you can reffer to
Lienard Wiechert Potential
Answer: You can use the Biot-Savart formula to find magnetic field with very good approximation, if electric field everywhere is a potential field (it can be expressed as gradient of a potential function). This is because the Biot-Savart field obeys the Ampere-Maxwell law with displacement current due to that potential electric field. In other words, for systems where electric field is a potential field, correction to Biot-Savart magnetic field due to displacement current is zero.
A charged particle moving with constant velocity has electric field that moves in space but if the speed is much lower than speed of light, at any instant electric field can be expressed as gradient of a potential function (giving a $\gamma$ - contracted Coulomb field). So you can use the Biot-Savart formula if the charge speed is low enough.
Comment: This answer is incorrect, simply compare lienard wichert  potentials and the biotsavart equivelent to a point charge. At any instant, there is an associated de/dt assigned to a point in space.
Comment: @jensenpaull Yes the Biot-Savart formula isn't exactly solution of Maxwell's equation. But for constant (no acceleration thus no radiation) and low (compared to $c$) velocity it is most often good enough. This is because for such motion electric field is almost a gradient of a scalar function and its contribution to magnetic field via "displacement current magnetic field" is zero.
Answer: dB = (µ/4π)(i/r²)(dlXr'), dl and r' are vectors, |r'| = 1 (r with ^)
i = dq/dt
dl/dt = v
dB = (µ/4π)(dq/r²)(vXr'), v is vector and |v| = v
B = (µ/4π)(q/r²)(vXr') = (µ/4π)*(q/r²)vsin(θ)
B = µqvsin(θ)/4πr²
comments:
two vectors u and t and θ angle between them, |uXt| = |u|*|t|*sin(θ)
when we have a function the equation dB = Constant*dq when you use integration you can get B=C *integral dq = C *q
Comment: Welcome to PSE. Your answer is not readable. I suggest you to learn editing your equations with MathJax.


Can you read this logo as "D" in negative space?

Question: I'm doing a project and I need a logo to represent directory. I would like to get some feedback. Does my icon deliver the message?
Comment: I like mike's answer, so I won't add an answer of my own, but none of the answers deals with the conceptual element: a small problem with your idea is that the arrows are pointing outwards and away (and, for Roman lettering, the wrong direction). Perhaps a directory is a container into which things get placed. You would speak top this more with a wide-to-narrow and left-to-right motion. Perhaps the arrows meet at the midpoint of the D's arc.
Comment: Using a logotype to represent an object like that has problems even if you successfully achieve a recognizeable letter, mainly localization. This may not be an issue for this project but it's good to develop a mindset early on that considers such things. Iconic representations are more universally understood, e.g. a folder with an arrow.
Answer: For us to perceive it as a D, you need something on the left side. It can be a line, an arrow, whatever. Your example up there looks like two arrows because that's what it is - with no other line to trick the brain. However, if something is added to the left side, the human brain automatically connects the dots and fills in the rest.
Examples of possible alternatives (quickly done up in Photoshop - merely examples and not finished products nor intended for use until fine-tuned).

As you can see, you would automatically see any of these as a D, much more so than the one you provided above. Play around with it, see what works best. Ultimately it's up to you, because as someone else mentioned, there's no need for it to look like a D unless you want it to.
Answer: I would say it's too light to make a "D". But maybe you can try to make the two arrows larger in order to close the shape on the left and make it look like a real "D". They don't have to touch each other, just be close enough to suggest a left line.
Answer: A logo doesn't have to overtly represent anything. It's nice when it does, but there's no hard-and-fast rule about it.
Do I see a D by default? No. Is that a big deal? I don't know. Only you and your client can answer that.
Just a general comment...I find the weight of the arrows too light for the size and color of the box it's in. You may want to beef them up a bit. In doing that, the 'D' may become cleaer as well.
Answer: I would say it's too weak to stand on it's own. If you use it in a logo with a word (so the D is incorporated into the word), the D could probably be more visible.
Answer: I have no problem seeing that as a D. Of course; it depends a little on the context, and it would be easier to grasp in its "habitat". @Henrik Ekblom has a good point with using it together with the name, but this is not always needed: it depends on the context you put the logo in.
If you are also asking if it is intuitively clear that it represent "directory" (I am guessing you mean directory as in telephone directory, not as computer directory?) that is a little harder. BUT, in context, it might be perfectly understandable. Never underestimate the ability for people to very quickly learn the logo and associate it appropriately. Sometimes spoonfeeding is not a good solution (a restaurant logo does not need to contain a steak, forks or checkered tablecloth).
A classic example of very elegant use of negative space, is the FedEx logo, who uses the white to create an arrow ("delivery! forward!")

There are, however, a number of ways you could make the logo a little more sophisticated, but this is of course extremely subjective. Personally, I would play making the D thicker, putting the name of the company/organisation at the bottom of the logo; maybe extending it outside the red box, using some more contrast.
Whatever you end up with; may I suggest that you pull the white D up a little. This for compensating for human visual processing: a little more air will prevent it from visually "falling down". Consider well framed artwork (there are an awfully lot of sloppy work here, curse on the mass produced!): it will have the bottom of the passepartout slightly higher than the top:
Answer: I'd put a reversed arrow in the center, to represent the normally empty gap inside the D. It might help people visualize it. Not sure if it'd look as good though, but it's worth a try.
Comment: Welcome to Graphic Design! You may want to read the introductory [tour] some time. Yours is an excellent idea, perhaps you can make a mockup and add it to your answer.


Help interpreting formula for multi-class hinge loss

Question: As I'm reading from wikipedia, and this Cross Validated question: Gradient for hinge loss multiclass, the gradient value for a training feature set is somewhat straightforward. However if I'm interpreting this correctly, this only gives a gradient value for the weight of the 'true' class. How do I find the gradients for the other weights? That is, if my total weight vector is [W1, W2, ... Wy... Wk], where y is the class of the training sample then what are the gradient/loss values for every weight that isn't Wy?
Answer: The answer at Gradient for Hinge Loss Multiclass gives you the Gradient per class.
Since the classifier for the $ j $ - th class is given by the row $ j $ of $ W $ (Which is notated at the answer as $ {W}_{j} $) all you need on each iteration is to update $ {W}_{j} $ according to $ {\nabla}_{{W}_{j}} {L}_{i} $ according to train sample $ {x}_{i} $.
Namely, $ {W}_{j}^{\left( k + 1 \right)} = {W}_{j}^{\left( k \right)} - \eta {\nabla}_{ {W}_{j} } {L}_{i} $, Where $ j $ is the index of the updated row, $ k $ is the iteration counter and $ \eta $ is the Step Size / Learning Rate..


What happens if a cron script tries to copy a directory at the same time as another process is writing to it?

Question: For example, if I have a java process that (once every 2 hours) takes a backup of a large file, like 500mb, and places it into folder A on HDD A, and I want to schedule a cron script to copy the entire folder A to HDD B once per day... what happens if the cron script happens to fire while the java process is in the middle of writing to folder A? Will it wait? Will it just ignore the file that isn't done being written yet?
Answer: In general, Unix commands treat files the same, whether they are open and being written to or not.  So if a cron job is using cp to copy a directory, what gets copied depends solely on what is in the directory at the time the cp command examines the directory.  If a file is only partially written at the time cp visits it, a partially written copy will be produced.  If you want to prevent such occurrences, you need to implement a locking scheme amongst cooperating processes to prevent concurrent access to the directory.
Comment: +1.  But if you're trying to make a backup, use `rsync` instead.    You can use it to perform incremental copying.
Comment: You do not need a locking scheme. You need an atomic update scheme. What I did for a similar problem is to copy new files into a tmp subdirectory then move them into place after the copy is complete. If you copy subdirectories then use a directory at the same level. Just make sure it is on the same filesystem.


Is there a category whose objects are sets, in which both products and coproducts are Cartesian products in the classical sense?

Question: In Rel, both products and coproducts amount to taking a disjoint union of sets. Is there a category whose object class can be interpreted as the class of all  sets, in which both products and coproducts amount to taking Cartesian products, in the classical sense?
Comment: Easy: let $\mathcal{C}$ be the category whose objects "are" sets, and whose morphisms $X \to Y$ are the group homomorphisms from the free abelian group generated by $X$ to the free abelian group generated by $Y$. This has the required property.
Comment: So you claim that $\hom(F(X \times Y),F(Z)) \cong \hom(F(X),F(Z)) \times \hom(F(Y),F(Z))$ and $\hom(F(X),F(Y \times Z)) \cong \hom(F(X),F(Z)) \times \hom(F(Y),F(Z))$? Neither is clear to me.
Comment: How trivial of a solution would you accept? For example, the category with a single object (any set of your choice) and one arrow.
Comment: Yes take $\mathbb{C}$ to be the category with objects sets and with a unique isomorphism between any pair of objects. This type of category has many strange properties amongst which one easily sees that the product of $X$ and $Y$ is any set $S$ (in particular $X\times Y$ will do), and similarly the coproduct of $X$ and $Y$ is again any set $S$...
Comment: I have trouble understanding what exactly are you looking for: for how you asked the question I would say that $\mathbf{Set}$, the category of set and functions, satisfies your requirement...... so what are you exactly looking for?
Answer: In the category of Abelian groups:
If $A$ and $B$ are abelian groups, the product $A\times B$ together with
$\iota_A:a \longmapsto (a,0)$ and $\iota_B:b \longmapsto (0,b)$ is a co-product. Since if $f:A \longrightarrow C$ and $B \longrightarrow C$ are morphisms of abelian groups, then $h:A\times B \longrightarrow C$, defined by $(a,b)\longmapsto f(a)+g(b)$, is the unique homomorphism making the required (coproduct) diagram commute.
This is only true for finite-products, but hopefully it answers the question.


Where should I keep the source files of the compiled applications?

Question: I use Slackware Linux and I install most applications from the source. I would like to know how to manage the source files, specially the header files, so they are available to other applications.
Comment: I'm not a Slackware user, but generally headers go under `/usr/include` or `/usr/local/include`. There should also be a `/usr/src` and `/usr/local/src` where you can put the source code.
Comment: Thanks, I knew about the folders `/usr/src` and `/usr/local/src` but I didnt know about the include folders. It seems that the system does not have those folders in the PATH thus I thought the `.h` files where no installed.
Comment: The `PATH` variable is only used to search for executables. Libraries are searched in a different set of directories and headers in yet an other set. If you use `gcc` there is an option `-print-search-dirs` that prints the default paths.
Comment: @Bakuriu: Thanks, I have to read more about `gcc`. In the first instance it worked when I included those dirs in the `PATH`. From now I will follow your advice and include them in the `LIBRARY_PATH`.
Comment: The actual environmental variable for header files is: CPATH
Answer: Best way to get an idea is taking look at the Slackware build scripts (located in sources/*/* in the distribution trees). There are also some additional Slackware package repositories, which contain lots of packages not found in Slackware proper, so you might not necessarily need to build everything yourself. Two of the well-known are Eric Hameleers' slackbuilds repo and slackbuilds.
That said, the install part of the application build system usually puts these files (headers) in the appropriate place, i.e. /usr/include or /usr/local/include, depending whether you are installing into /usr or /usr/local (the latter being usually default).
As for the sources - generally speaking you should not need anything else than headers once you compile the application (apart from any header files you need when you want to compile another piece of code against it). Unless you want to actually develop the software, you discard the sources right after compilation. And if you want to develop you usually keep a separate tree somewhere under version control and do not build your packages from this devel tree, rather from a more stable one.
Last but not the least, you really want to make a package first and only install that (i.e. not running make install as root directly), since it makes system maintenance easier (and you don't have to keep the sources to be able to run make uninstall).


Maximum number of Sensors supported by raspberry pi

Question: i would like to know how many sensors can be connected to raspberry pi at a time
(i would like to connect sensors like temperature sensor,humidity sensor,pir motion sensor   and  3 to 4 leds)
Comment: Hello and welcome to RPi.SE Without further information and specific details about that sensors and how they are going to be connected it is however nearly impossible to answer that question.
Comment: i'm doing pi-planter
(http://www.raspberrypi.org/tag/piplanter)
i would like to add sensors like soil ph meter,PIR motion sensor,,soil moisture sensor,temperature sensors and a motor switch. Is this possible in RPi B+ model?
Comment: You can build ever-more elaborate multiplexing structures to connect as many sensors as you want but ulitimately you reach a point where you just can't get the data out at the rate you require. When you will reach this point is massively situation specific. So there is no straight answer to this question.
Answer: This depends on many factors. Main limitation is the number of programmabble GPIO ping you have. In model A and B, there are 17 programmable pins (rest are +5v, 3V3 or GND). On model B+ you have 26 programmable pins (rest are +5V etc.). If you ever run out of pins, you can make a multiplexer which will be able to handle higher amount of devices on the same amount of pins.
TIP: For analog sensors i used MCP3002 Analog-Digital converter. The full wiring takes 5 GPIO pins, 2 power pins and GND.


Is everything identical to itself, or merely every existing thing?

Question: One of the properties of identity is that everything is identical to itself. But, does "everything" mean literally everything, or merely every thing that exists? For example, I don't think 1/0 = 1/0, because 1/0 is undefined, so it can't equal anything, not even itself. But what have philosophers written about this issue?
Comment: Per Quine's ontological commitment expressed in his '*On what there is*' your mentioned law of identify only applies to existent objects, preferably only in the sense of FOL as its basic knowledge. Usually your 1/0 is undefined in most formal theory, except perhaps Robinson's nonstandard real analysis...
Comment: 1/0 is malformed and not even all well-formed expressions represent objects in a theory. That a = a does not apply to those does not subtract from "literally everything". But the "thing" it applies to does not need to exist, it just has to have to be an object in the theory. It applies to fictional characters, for example.
Comment: Sometimes the identity law is expressed as a conditional, so we might still say, "If 1 is divided by 0, then 1 is divided by zero," per, "If A, then A," and what is amiss with that? Likewise we might say, "If A is not A, then A is not A," and so on, although we might add, "If A is not A, then A is A and not A is not A, plus not A is A," as well.
Comment: When we say "there is no such number as 1/0" we mean that there exists no mathematical object which instantiates the idea of that arithmetic operation, not that there exists something called a 1/0 which does something called not-existing.
Comment: Reference: see [Identity](https://plato.stanford.edu/entries/identity/). Your puzzle is not about identity, but about "thing": what are non-existing things?
Answer: Some philosophers treat x=x as coextensive with "x exists". In some formal work, they actually define "x exists" as x=x. On the other hand, this could also be viewed as pushing the question of existence down into the interpretation, because x=x only has meaning if the interpretation assigns a value to x. If so, one could argue that x=x is only being used because it is a convenient predicate available in any logic with equality, and one that is true of everything. Any other predicate that is true of everything would work just as well in a theory that had the predicate. Examples include "Is a member of the universal set" in a theory that has a universal set or "has parts" in an atomless theory of mereology.
As to your question,

does "everything" mean literally everything, or merely every thing that exists?

What would it even mean to say that there is something that doesn't exist? Your example of 1/0 is not very convincing, because (in normal arithmetic) there is nothing that 1/0 names, so an expression of the form 1/0=1/0 is neither true nor false, but ill-formed. It's like asking "Does three men?" It doesn't mean anything.
Now, there are metaphysical theories that everything exists that we can try to describe, even something like 1/0 and round squares and Sherlock Holmes. This is called Meinongianism after Alexius Meinong. Meinongian writers generally make some sort of distinction between existence and being real or actual, and some of them countenance different sorts of predicates applying to the non-real objects, or those predicates applying in a different way. In these theories, a=a might not apply even to some things that exist.
UPDATE:
Reading this article, I learned that my terminology was wrong with respect to original Meinongianism. What I was describing was the work I've read (mostly Zalta and critics of Meinongianism), which is apparently discussing a modified form of the theory. The original work (which I haven't read) distinguishes between a thing's being and the thing's existence. Meinong would say that there is a flying horse named Pegasus (Pegasus has being) but the flying horse named Pegasus doesn't exist.
Answer: You can view the question in several ways. For example, you can consider 1/0 to be an expression, which clearly does exist as I have just typed it, in which case you can say that 1/0 is the same as 1/0, meaning that the expression is equivalent to itself. Then you can consider this particular instance of the typed expression 1/0 and say that clearly it is identical with itself, just as the inscription on Karl Marx' gravestone is identical with itself. The fact that 1/0 is undefined is in some ways, at least, no different to the undefined nature of the string kspltvrymuuub, yet I suspect you would have no problem in accepting that kspltvrymuuub is the same as kspltvrymuuub, and that this particular string kspltvrymuuub is identical to itself.
In what I have said so far, I have evaded your point, somewhat, by adopting the tactic of making an unreal thing real by equating it with its typed label-  typed characters being definitely real. I think you can argue that concepts, such as the concept that the typed expression 1/0 represents, have mental counterparts as well as typed counterparts, so that when you think of 1/0 there is some mental state associated with it, and if you believe mental states exist then you can apply the principle identity to a mental state (albeit with some qualifications).


set timeout on certain rails controller action

Question: I have quiz app where there are multiple questions with options to select.
The controller actions are as follows
replies_controller.rb
#the questions appear on `new` page

 def new
    @quiz = Quiz.find(params[:quiz_id])
    @reply = @quiz.replies.build
    @quiz.questions.each {|question| @reply.answers.build(question: question)}
  end

#once user submits the answers it goes to create
  def create
    @quiz = Quiz.find(params[:quiz_id])
    @reply = @quiz.replies.build reply_params
    if @reply.save
      redirect_to @quiz, notice: "Thank you for taking the quiz"
    end
  end

What I am trying to achieve is , after like 30 minutes it should automatically create. If creating empty params is a bad idea then at-least there should be way to show a message or redirect to root page after 30 minutes. How can I achieve this ?
Comment: This looks like a client-side concern, not server related. You can use a javascript timer to auto-submit the form after 30 minutes.
Answer: I think your best bet is going to be to use something like Sidekiq to delay the creation of a reply. You can create an empty one and send the id, along with the params to a worker and delay the rest of the work for a set period of time, like 30 minutes. You'll need a worker, something like a ReplyCreationWorker to call in the controller, then you can redirect with a message to check back in 30 minutes.


2 Navigation Bars On Nearly Identical Pages, Yet Different Results and Can't Control UL LI Padding and Margins

Question: Recently I created a new horizontal navigation for my 2 sites but on one site it looks good, yet on another I am having trouble controlling the positioning.
For example, If you review the horizontal navigation links at the bottom of the header image here: http://classifieds.your-adrenaline-fix.com/ you'll likely agree that it looks good but if you click any of the horizontal links these will take you to the main site where you will see the same horizontal navigation but the problem is I can't gain control of the positioning nor can I seem to figure out why the 2 are different with nearly identical HTML and CSS.
If anyone wouldn't mind taking a look at the link I provided above you'll see what I'm talking about and if anyone wouldn't mind showing me what Im missing, I'd be most appreciative and I thank each of you in advance.
PS; I've been trying for hours...
Answer: On the page that looks correct, your
 has the following styles defined in form-css.css around line 70
list-style-type: none;
padding: 0px;
margin: 0px;

The main page does not have this styling.  The important parts being the padding and the margin. Default styling on a list usually gives some pad and margin to a ul, which is what we are seeing in the main page.
Comment: Thanks @Lee Quarella!! I completely forgot about form-css.css. I'll be looking into correcting this
Answer: I compared the CSS for the two pages using chrome developer tools. As you said they are almost identical in HTML and CSS but I did find a difference.
This page:
http://classifieds.your-adrenaline-fix.com/
**The ul tag has some css properties applied to it which are not present in the other page( the page which is messed up) namely:
ul {
    list-style-type: none;
    padding: 0px;
    margin: 0px;
}

This css clip I found in the form-css.css page.
Removing this css part, messes up the page where the horizontal navigation is looking fine as well.
By adding these CSS properties to your ul tag for the horizontal page links for the other page(http://www.your-adrenaline-fix.com/) should fix it.


Allow USB debug pop-up not showing while installing CyanogenMod on Galaxy S3 i9300

Question: I'm trying to install CyanogenMod on my Samsung Galaxy S3 (i9300, international). Had no problems, until I had to switch to the pc installer.
I'm stuck on the screenshot underneath:

I have enabled USB debugging on my device (since the day I got it), did all the stuff asked up until now, but I can't continue here. It doesn't show any pop-up on the device, USB debugging is enabled.
Can anybody help me?
Much appreciated!
Answer: The solution to my problem was simply revoking all authorisations granted to computers already. After rebooting both my Galaxy S3 and my laptop, the pop-up appeared again and I could continue the installation of CyanogenMod, which has now succesfully completed.
Answer: I also got the same issue in my lenovo mobile. Initially I thought the issue is with my mobile.
But actually the issue is the adb don't have enough permission to read the rsa key to communicate with the device. When we run adb server it'll create a folder named .android(Linux - /home/--username--/.android, Windows - C:/Users/--username--/.android) in the home directory of the current user which contains the adb rsa key files used to communicate between the devices. When I check the folder is assigned with root permission(I am using Ubuntu 16.04 and I don't know how its assigned).
So I deleted the folder using below command. Use the particular method to delete the folder based on your operating system. Below I mentioned for linux.

sudo rm -rf .android

Then restarted the adb server using below command.

adb start-server

Now It created the .android folder with the current user permission. Once done this I got the Allow USB debugging dialog.
Hope it help someone.


how to be notified about incoming transactions instantly?

Question: I'm creating a platform which users are able to receive ETH on their own wallets (addresses). They will give the addresses to others, but the question is how can I be notified that new transactions happened on that addresses automatically?
One way is to check the history of addresses periodically, but by having many users, this mechanism will consume a huge amount of resources. Is there any appropriate way to know about valid incoming transactions instantly?
Answer: Geth has undocumented API function getModifiedAccounts that returns list of addresses whose state (balance is a part of address state) was modified between two given blocks.  You may use this function to query the list of modified addresses for every new block (or several consequent blocks), then filter returned list dropping addresses that your are not interested in, and then obtain balances of the remaining addresses one by one.
However, this method is probably not available on Infura, so you will have to run your own Geth node to do the trick.


Data structures for bioinformatics

Question: What are some data structures that should be known by somebody involved in bioinformatics? I guess that anyone is supposed to know about lists, hashes, balanced trees, etc., but I expect that there are domain specific data structures. Is there any book devoted to this subject?
Answer: The most fundamental data structure used in bioinformatics is string. There are also a whole range of different data structures representing strings. And algorithms like string matching are based on the efficient representation/data structures.
A comprehensive work on this is Dan Gusfield's Algorithms on Strings, Trees and Sequences
Comment: Agree.  Gusfield's book is very comprehensive.
Answer: A lot of introductory books on bioinformatics will cover some of the basic structures you'd use. I'm not sure what the standard textbook is, but I'm sure you can find that. It might be useful to look at some of the language-specific books:

Bioinformatics Programming With Python
Beginning Perl for Bioinformatics

I chose those two as examples because they're published by O'Reilly, which, in my experience, publishes good quality books.
I just so happen to have the Python book on my hard drive, and a great deal of it talks about processing strings for bioinformatics using Python. It doesn't seem like bioinformatics uses any fancy special data structures, just existing ones.
Answer: Spatial hashing datastructures (kd-tree) for example are used often for nearest neighbor queries of arbitrary feature vectors as well as 3d protein structure analysis.
Best book for your $$ is Understanding Bioinformatics by Zvelebil because it covers everything from sequence analysis to structure comparison.
Answer: In addition to basic familiarity with the structures you mentioned, suffix trees (and suffix arrays), de Bruijn graphs, and interval graphs are used extensively. The Handbook of Computational Molecular Biology is very well written. I've never read the whole thing, but I've used it as a reference.
Answer: I also highly recommend this book, http://www.comp.nus.edu.sg/~ksung/algo_in_bioinfo/
And more recently, python is much more frequently used in bioinformatics than perl. So I really suggest you start with python, it is widely used in my projects.
Answer: Many projects in bioinformatics involve combining information from different, semi-structured sources. RDF and ontologies are essential for much of this. See, for example, the bio2RDF project. http://bio2rdf.org/. A good understanding of identifiers is valuable.
Much bioinformatics is exploratory and rapid lightweight tools are often used. See workflow tools such as Taverna where the primary resource is often a set of web services - so HTTP/REST are common.
Answer: Whatever your mathematical or computational expertise is, you are likely to find an application in computational biology. If not, make this another question of stackoverflow and you'll be helped :o)
As mentioned in the other answers, somewhat timeless are string comparisons and pattern discovery in 1-dimensional data since sequences are so easy to get. With a renewed interest in medical informatics though you also have two/three-dimensional image analysis that you run e.g. against genomic data. With molecular biochemistry you also have pattern searches on 3D surfaces and molecular simulations. To study drug effects you will work with gene networks and compare those across tissues. Typical challenges for big data and information integration apply. And then, you need statistical descriptions of the likelihood of a pattern or the clinical association of any features identified to be found by chance.

Data structures for bioinformatics


Development on a single VF and apex class

Question: I don't whether this question should be posted here, because this is related to dev process not any issue with salesforce. My issue is: we 3 are working in a same org, i.e: 2 guys are working on a same VF page at a same time and i am working on apex code. other 2 may have same requirement to add some code to apex class also. As we know that this process will overwrite each other code. So we have created 3 clones of VF and apex class, then we work on it and after compare we update it. If I go with eclips to this may overwrite each other code. Is their any effective way to over come this issue. Please guide us to fix this issue. We cant assign a single whole work to a person because their is lot of work to do.
Comment: If this single page is complicated, you might well find that using a [thin-controller](http://salesforce.stackexchange.com/questions/89043/salesforce-code-review-best-practices-for-controllers/89046#89046) approach improves the code and has the side effect of allowing the 3 people to work on separate files. Perhaps apex:components could achieve the same result for the page content.
Answer: Not sure whether we are following the best approach or not. But as in a team of many developers working on the same package of code we are basically following this:
We used trialforce. Each developer has its own trialforce org and github branch. So basically each developer is working on an independent org and commit into an independent branch. We merge into a main branch and resolve conflicts there. For deployment, we are using Circle CI. But I am pretty sure a bunch of other deployment tools can do the same thing - Jenkins, Gearset, etc.
Hope this helps.


SharePoint Online Export and Import Managed Properties

Question: is there a way to export/import managed properties in SPO using PowerShell? I looked around and it looks like there is no way of doing this via PowerShell.
Answer: I am afraid we cannot export or import the managed properties in sharepoint online by PowerShell command.
It is by design.
Because in sharepoint online, we only can use the client-side object model.


I would like to get this patent assigned to my company since it infringes on DQWA, which is assigned to Ether-2. How do I do that?

Question: In reference to the patent: US20140148197
Answer: The linked document is an application. The issued patent is US9702961B2. If you believe it infringes on a patent your company owns, then the assignee will need to get a license in order to utilize it. Its up to your company to initiate a law suit if you think your intellectual property is being infringed. I'm not a lawyer, but my understanding is that patents are property and this one would belong to assignee: Intel Corporation. I do not believe the US government can just assign the patent to another company. So there is no way to get the patent to be assigned to your company short of purchasing it from Intel.
Comment: There is a way to sue for ownership if the idea was stolen. Doesn't seem so from the question though.