How do I erase all old programs using the new scratch type Education software?

Question: I have 24 Lego Mindstorms EV3 bricks that have old programs and the bricks are named. I want to erase them so they can be used for new students. In the older Mindstorms software I would just reinstall the firmware from the tools menu. That would easily clear off the bricks. How do I do that with the new scratch type Mindstorms Education software? I don't see that command.
Comment: I am using the new Lego Mindstorms EV3 Education software for PC downloaded from the Lego website. It does not seem to have any way to erase all old programs and to reset settings the previous students may have changed..
Comment: Are you using the EV3 Microsoft Makecode site? The website is incapable of interacting with a real EV3, that's why it makes differently-formatted programs and uses a *simulation* of the EV3.
Answer: The LEGO Education Website EV3 firmware update page lists two options.

Use the EV3 Device Manager web page. The instructions are not entirely clear, but if you visit the web page with Chrome (recommended), Safari, Edge, or Internet Explorer, click the Available Bricks (0) button and wait a very long time, it will eventually pop up a dialog asking to download and install an EV3 Device Manager program to your computer. The EV3 Connection Manager program runs in the background on your computer and communicates with the EV3 Connection Manager web page in the browser. After installing the separate background program, the web page will be able to connect to your EV3. Then you can use it to update the firmware. It does not appear that this method gives you the option of selecting which firmware file to use. It will likely give you v1.10E, which has some known issues (EV3 acts as USB mass storage device which doesn't always work, and on-brick data log app is missing). But that version should work fine for most uses.

If you have Windows, Chromebook or older macOS (10.14 Mojave or earlier), you can also install the older software and use that. It is available from the LEGO Education retired products download page. (Android and iOS versions might not work due to lack of USB connectivity needed for firmware update.)
Comment: I do have an old Macbook  at home that can probably run the older Lego software. Now that I see it is still available I can use that to clean up the bricks, thank you! Too bad the new software does not have this feature, oh well.
Answer: Just do a hard reset on your brick.  Each student can do that
Comment: Good answer, but perhaps expand by explaining how one does that?
Answer: I looked up hard reset. Plug into USB, hold down back, center and right buttons. When it shuts off release the back button, then the rest. The brick will reset. Thank you so much, you saved me so much time!!


How do the options in the Post Processing tab work?

Question: Can someone explain what the Compositing and Sequencer check boxes in Render Settings do?
Basically I rendered a scene with several layers, then used the compositor to stitch them together. Next I saved out my layers as multi layer EXR and in the compositor replaced the Render Layers with the EXR file.
At that point pressing F12 to render seemed to not do anything. I googled around and I found solutions that advised to turn off "Sequencer" ... however in my case what solved the problem was turning off "Compositing".
So basically the problem is solved but it would be nice to understand how things work and what exactly happened.
Answer:
Those two check boxes toggle using the compositor and sequencer.
If you are using any compositing nodes, then you will need to have the Compositing box checked.
If you are using the VSE for anything, then likewise you will need to have the Sequencer box checked.
If you are just rendering from a 3D scene, then you can uncheck both boxes.
Now most of the time you can safely leave both of them checked.
When the VSE is empty it will do nothing. However when the compositor is empty, and the Compositing box is checked, like your issue, the render will turn out blank.
See my answer for a bit more on the compositor's required nodes.
Answer: The Compositing checkbox enables the usage of the RenderLayers Compositor during a render. Likewise, the Sequencer enables the Video Sequencer Editor. This is a tool that can be used to add audio, misc. video and images, transitions, etc. to a render.
Additionally...
The VSE is the only totally free high quality video editor in existence. It does not have many transitions, but Blender's Python scripture and 3D Features can combine or work separately to create many custom ones.
Hope this helps and happy Blending!


Kalman Filter : How measurement noise covariance matrix and process noise helps in working of kalman filter , explain intuitively please?

Question: How noise covariance matrix and process covariance matrix helps in improving the state estimate, can some one explain intuitively without mathematics ?
Comment: they really don't improve a state estimate without noise, you use a state observer.   The reason why you use a filter is when measurements are noisy.   A KF needs measurement noise because it is based on that assumption. Noise is also used to model uncertainty in the model but this doesn't improve the accuracy of the state estimates
Comment: Hi ? you have your answer, would you mind leaving some feedback? Upvote if useful, accept if answered, or ask further questions if still confused.
Answer: Considering a linear dynamic system framework, if there were no noises in the process equation and measurement equation, then one could use deterministic means to compute the state exactly, without any need for an estimator.
However, the unavoidable presence of noise in the state transition and the measurements make it impossible to compute the state exactly but only approximately. As the measurements are not true but in error.
Kalman filter (similar to other statistical estimators) improve the state computation by referring to the statistical character of the noise present in the measurements and state transtitions. Kalman filter also benefits from the dynamic equation of the system in predicting the state update.
So those noise covariance matrices are used to specify the Kalman gain K, which tries to correct the error in the deterministic computation of the state update.


How do I tell a professor who tells me he'll send in a recommendation but doesn't that I don't need his letter anymore?

Question: My professor agreed to give me a LOR. However, despite many reminders, he has yet to send it in. I called him up a week before the deadline and he was annoyed at this. I then considered asking someone else but he emailed me asking me for supplementary documents. Again there has been radio silence from his side after that. Now, the deadline has passed. I think professors can still send in LORs and I've asked another professor to write a LOR for me after explaining my situation.  My question is do I email my earlier reference to tell him I don't need his LOR anymore? How do I word this email? Should I show my indignation at being taken for a ride?
Answer: If you don't feel angry at your professor, you could drop them a note once the firm deadline has passed, so that they avoid wasting time on writing a letter that's not needed anymore, or they don't feel bad about never having gotten around to doing it. I could imagine doing this with some colleagues whom I know are very busy.
In this case you could write something like "Dear professor, I'm writing back about the letter of recommendation that I originally requested from you on [date]. You had agreed to write this letter, but I have not received it. I just wanted to let you know that the deadline for submitting letters has passed, so it doesn't make sense for you to work on this anymore. Instead, I have asked [other prof] to write a letter explaining the situation."
If you will be working with this professor again and would like to set a boundary, you could add something like "It felt stressful for me to make this alternate arrangement without having a response from you about the original letter. In the future, it would be really helpful if you could respond more quickly to email about this kind of matters." Or something like this, although that's hard to word.
On the other hand, if you feel indignation at your professor, as seems to be the case, then I don't understand the purpose of sending a further email at all. What good would it achieve? If the letter of recommendation arrives at some later time, you can simply explain that the deadline has passed so you can't use it, but thanks nevertheless.
Comment: I gently suggest this approach is not the way to go, especially if you intend on seeing this person in any capacity in the future.  Bilkokuya's answer is how I'd handle it.  It is not your job to chastise this professor, you just need to thank the person (with no snarky remarks), and move on.
Comment: Thanks for your feedback! Please note I am not suggesting being "snarky" or "chastising", I just suggested pointing out politely and nonviolently what you would like from them in the future. I agree that this only makes sense if you expect to continue working with the person (it's probably not worth it otherwise), but in this case it may be worth it. I agree it's tricky, and may not be possible depending on circumstances, but it can also be useful to make the working relationship smoother in the future. I'd say it depends on the current relationship between the op and their professor.
Comment: Politely thanking the person is the best and safest route to any future relationship. There is no price for politeness and a high price for taking on someone, however subtly, in a power position, especially when you don't know the whole picture. The purpose of sending an email is to be respectful of another person's time, and it gives you the chance to make a good impression and behave like a mature professional.  If you absolutely have to have this conversation, it should be in person.
Answer: I'd suggest avoiding anything that could cause conflict, and anything that feels like you are wanting to vent. It will have been extremely frustrating for you, but telling the professor that will do no real good and risks creating enemies where they are not needed.
If you feel you wish to contact them, it might be worth sending a quick email to thank them for helping you with this, and apologising that it is no longer needed (you do not need to say why, or that the deadline has passed - you are just avoiding them wasting their time writing the letter now). It may seem odd to apologise when you have done nothing wrong, but from their perspective - you have just badgered them repeatedly/added stress to their life and are now saying it was for nothing. It is not saying you were in the wrong, it is just maintaining a relationship with them.
If you don't care for them at all and don't see a bad relationship with them causing you any problems in the future (note: I've found I'm still in touch with most of my old professors, or people who know them/worked with them, in some form or another) - just don't say anything.
It might feel like they owe you an apology, or that they should recognise how they stressed you out - but that's really just for personal feel-good. It doesn't help your professional career at all to chase that.


Is "Reachable Object" really an NP-complete problem?

Question: I was reading this paper where the authors explain Theorem 1, which states "Reachable Object" (as defined in the paper) is NP-complete. However, they prove the reduction only in one direction, i.e. from 2P1N SAT to Reachable Object. This only proves that the problem is NP-hard; do we not need to prove the reverse direction (2P1N to Reachable Object) to prove NP-completeness?
Comment: I just want you to know that the symbol is `\in`, not `\epsilon`.
Comment: The authors have not proven that the problem lies in NP, they have only _claimed_ that it does (and that it is easy to prove this). They do have proven NP-hardness.
Answer: A problem $P$ is NP-complete if:

$P$ is NP-hard and
$P \in \textbf{NP}$.

The authors give a proof of item number 1. Item number 2 is probably apparent (and should be clear to the paper's audience). For the proof of item number 1, you only need a (many-one) reduction from some NP-complete problem (e.g., SAT) to $P$; there is no need to construct a reduction in the opposite direction.
Comment: In case anyone is still confused, 2 is trivial because to be in NP means that you can quickly (polynomial time) verify a solution to the problem. Here, a solution can be verified by simply performing the swaps as stated in the solution and checking that you reach the desired object.
Comment: @StevenLowes The only thing you would still have to verify is that the number of swaps required is polynomial. This too is not that hard to see, as I explain in my answer.
Comment: I had misread the paper and assumed it was not possible for a sequence to require more than N swaps - you're right :)
Comment: @StevenLowes: Well, it had also better be (expressible as) a decision problem. There are NP-hard problems that are not decision problems at all, which are obviously not going to be in NP no matter how easy they are to "verify."
Answer: The authors claim that it is easy to show that the problem lies in NP. To prove this claim, take a sequence of swaps that leads to a state as a witness that the state is reachable. Given such a sequence of polynomial size, we can verify in polynomial time that the state is indeed reachable by performing the swaps.
What remains to be shown is that there is a sequence of swaps that has polynomial size. Note that since each agent has strict preferences and will only swap if it can make a trade that gives it a better object, each agent can swap at most $n$ times. As there are at most $n$ agents, each sequence of swaps has at most $n^2$ swaps.

I think that if there were non-strict preferences, it might be possible that some items will have to move across long cycles to reach certain states, and that in particular there exist states where all sequences of swaps have exponential size. However, I cannot think of an immediate example of such a problem. At the least, it is no longer 'easy' to show the problem with non-strict preferences is in NP.


How should I connect a new timer switch?

Question: trying to install a new 4 hour timer switch for my bathroom vent.  the new timer has 4 wires green (ground) red white and black and they are labeled as to where they should go.  but the problem is that there are three black wires currently connected to the old switch and the whites are tied together.  I know that I need to tie the whites to the existing whites but I am trying to figure out why there are three black wires in the box all connected to the old switch.  on the old switch looking at the back there is one black wire in the top middle which I believe is the hot, one black wire in the bottom middle of the switch which I believe is the load but the third one is attached to the left side top screw could this also be a neutral. hope you can help
Comment: A photo of the switch would be helpful it sounded like a 3 way to me is 1 screw black and 2 brass colored ones?  It could be a jumpered pair as Paul Logan answered but they are usually side by side on a single pole switch.
Comment: how can I send a picure
Comment: Post it to a public site like imager and put a link in your answer and someone will edit it in.
Comment: Can you post a photo looking into the back of the box?
Comment: having a hard time sending pictures, however the back of the box the whites are all tied together and the three black wires are coming thru the back of the box.  my guess is that two of the black wire make a loop to send power to another fixture.
Answer: That third wire is feeding power on to the next item in your house.  No worries.  Just connect it in with the full time power lead.  PCL
Comment: so what you are saying if I get this correct is to twist the two power leads together allowing the power to continue on.
Comment: and just to make sure the power leads are the hot wires correct.
Comment: That is correct.


Plants vs Zombies on an iBook G4 - can I fix the gameplay being much faster than normal?

Question: I'm playing Plants vs Zombies on an iBook G4 - can I fix the gameplay being much faster than normal? I don't see anything about it in the options menu, and there doesn't seem to be anything else I can do. Is this how the game is supposed to play on Mac or am I missing something? The game audio is just fine, and I don't notice anything else being wrong.
Comment: Could you elaborate a bit on why you think the game is running faster than it should be?  Have you done any research or compared notes with online playthroughs, for example?
Answer: There is no such thing as fixing it to a faster gameplay. There is only one speed in the gameplay, which is fixed. However, if you're not using a Mac (which is the case unfortunately), then you can go here
http://www.techspot.com/downloads/3131-game-speed-adjuster.html      to download a gamespeed adjuster to increase your gameplay speed.
Answer: I am having this issue as well. The game runs at 200% speed on my iBook G4 1ghz model. I am assuming the speed at which the game is running at is tied to the framerate/clocks of the cpu, which is odd cause most releases after the G3 era should've already gotten this simple thing right. But it doesn't seem like that's the case however.
My suggestion would to be just play it at that insane speed and put down as many peashooters and sprites to artificially lag the game down to an acceptable speed (which is absurd but I have done it ), run it on the recommended specs which is a slower G4 chip. Or just play it on a device where it is properly optimised like a modern smartphone or computer. Cause this PPC port is just not great.


Test and developer of the psychological approach. Avoidance of tensions implement, but how?

Question: Many testers are aware that sometimes it is not easy to mediate between developers and testers or to find a common approach.
Sometimes, anger also tends to rule on both sides. Within ISTQB this area is also described and some right points are mentioned.
From my experience, one should approach certain issues very carefully, build bridges and find common ground. To have an open ear for the problems, but also to recognize grievances in the processes early and to solve them.
What has always been clear over the years, however, is that the test department is only seen as an appendix to the development. How often in 20 years QA has heard the sentences "Test, oh we'll do that later", "We don't need a test for that at all". But what has also improved through the Scrum process is that the individual test is defined as part of the team, at least in this process. But tensions are also unavoidable.
I would be interested:

How do you avoid tensions in the processes?
How can the testers be better integrated into the processes?
Which psychological approach should be used if the tensions between testers and developers hinder existing processes?
Answer: I'm not sure about this. the part where devs and testers are having "tension" are so year 2005... anyway to give my personal opinions
How do you avoid tensions in the processes?

respect is the key

How can the testers be better integrated into the processes?

Include the testers in all plannings, meetings or just anything that involves their opinions

Which psychological approach should be used if the tensions between testers and developers hinder existing processes?

If you have existing processes, discuss to them again those processes, if they can't accept the process get their thoughts why and have them reform it and finally agree on something


How to measure electric motor torque?

Question: I need to measure torque output of a PM DC electric motor.  My plan was to use a current clamp to log the current vs time, a voltmeter to measure volts vs time, and an encoder to log rpm vs time.  Then I would use the equation
T = (7.0429*I*V)/n to get torque vs time.  Where T is torque in ft-lb, I is current in A, V is voltage in V, and n is angular velocity in RPM.  This comes from the link between power, torque, and rpm, and the 7.0429 is just to get units of ft-lb.  I don't have the efficiency and I can't get the stall or free load values because its installed in a machine.  I do have a plot of RPM vs torque and Amps vs torque on the same plot.  Can I use this to back out torque values as I log current and rpm?
Comment: To make it simple, torque is (roughly) proportional only to the current. It doesn't rely on voltage. Mechanical power is (roughly) proportional to both current and voltage. Multiplying by voltage then dividing by speed does nothing. So you just have to measure the current and calibrate the value to mechanical power you measured outside.
Comment: "I need to measure torque... I do have a plot of ... Amps vs torque" - if you can measure Amps then that's all you need! (assuming the plot is accurate....)
Comment: I thought about that, but then there is a "rated power" and its listed at a certain rpm, with certain current, and certain torque.  If I take that specified current, and use that value on the plot, and then find the matching torque, it doesn't match what is listed under "rated power" values.  The plot says its about 3 ft-lb, where at "rated power" the torque value given was 1.91 ft-lb.
Comment: http://simplemotor.com/calculations/
Comment: You are measuring current, and you have a torque vs current plot.  Can you not use these to estimate torque?  The difficulty with estimating torque based on the input power is you don't know what your losses are.
Comment: Can't measure torque because it's in a machine, unknown load, unreliable specs - you're screwed.
Answer: Keep it simple. To measure the torque simply create a transversal arm attached to the motor using a known length. Let the whole motor free to turn (not the shaft, the outside case) along with the attached arm. The arm tip, opposed to where it's attached to the motor, can then be placed on a balance. You can measure the torque now using the balance measure and the arm length.
For example: if length = 0,3m and the balance indicates 100g than your net torque at the specific engine speed equals 0,1Kg x 9,8m/s^2 x 0,3m, in N.m
Be sure to calculate the arm length considering the motor center point to the arm point that touches the balance.
Answer: If you can calculate input power vs. speed, then extrapolate to estimate input power and current at stall, that would give you I squared R losses vs current. From that you can calculate a resistance value including brushes and commutator. You could then calculate I squared R losses at any speed and subtract from input power to get a closer value for mechanical power. Without no-load data to determine friction and windage losses, you probably can not get any closer than that to mechanical output power and torque.
Comment: If it is possible to lubricate the motor, some of the 'no-load losses' can be reduced.
Comment: The details of the plot you have didn't sink in before I wrote my answer. I agree with the comments, the torque for any given current will not vary much when operating on other speed torque curves obtained by reducing or increasing the voltage from the voltage for which the plot was made.

How to measure electric motor torque?


How to optimize my HHL algorithm on qiskit?

Question: I am following this HHL tutorial to solve the $Ax=b$ problem and have been using the general (inefficient) approach with the BasicAer simulator that they describe in section 4a. I would now like to run on the actual IBMQ machines but I am finding that my circuit depth and CNOT counts are quite high. To solve this issue, I would like to optimize my circuit. In section 4b of the tutorial they outline a method of optimizing their specific problem which substantially reduces the qubit count, circuit depth, and CNOT count. The problem I am having is figuring out how to extend this to larger matrices $A$ than the $2$x$2$ that they use. Is there a general approach to optimizing an HHL circuit?
Answer: There isn't any specific method to optimise HHL other than using the PassManager from Qiskit, but this is a more general circuit optimisation.
With the newest devices it might be possible to run larger circuits due to the reduced error, otherwise you will have to manually find circuit reductions.
In the last page of https://arxiv.org/abs/2009.04484 you can find the circuits for the example mentioned in the textbook and for the case of a $4\times 4$ matrix, maybe this helps to run your circuit.
Comment: The optimisation from the notebook is very specific to the problem and was necessary because of the limited capacities of the hardware. HHL itself is quite optimal, there are some improvements in the literature but in general it is not trivial how to implement these because they use black-box calls, which is not supported in qiskit.
Comment: The inefficiencies then come from the different parts of the algorithm - state preparation, hamiltonian simulation,... and from the qiskit point of view the biggest inefficiency which will not be overcome for general systems in the short term is hamiltonian simulation (within QPE), and this is because the black box assumptions made in the literature that treats how to simulate general sparse matrices.
Comment: Additionally, I do not understand why qiskit's HHL general algorithm is not already optimized. For example in the tutorial that I linked in the original question, they provide a general algorithm and then an optimized one. It seems to me that the general algorithm is not useful since it creates a circuit with very large depth and too many CNOT gates. Is the inefficiency of the general HHL algorithm entirely due to the number of ancillary qubits required for the QPE? Are there other factors which contribute to the inefficiency?


With a single entry visa, can I visit Ghana and return to India?

Question: I am a student in India with a single entry student visa, a resident permit valid for one year. I am from Ghana. I want to go back to my country for two weeks and come back to India. Can I exit and return with the single entry visa and the resident permit which I have?
Answer: No, you are not able to leave India and re-enter the country on your current visa. Your single-entry visa allows you into India one time only and, as you are already there, you won't be able to exit and return.
This is the usual practice, according to the Ministry of Home Affairs,

How may 'entries' are allowed to foreign students?
Normally one entry. However, on bonafide reasons, a foreign student can apply for additional entries at:
Visa Facilitation Centre
  Foreigners Division
  Ministry of Home Affairs
  Jaisalmer House
  26, Mansingh Road, New Delhi – 110003

And, for convenience, the directives from the Foreigners Division:

Foreign nationals in India may require various services like Registration, Visa extension/conversion etc. For this purpose, various powers have been delegated to the FRROs/FROs which are available on the weblink.
The foreign nationals are advised to visit the concerned jurisdictional  FRRO/FRO for such Visa related services.
If any service is required by foreign national which is not covered in the above mentioned delegated powers, even then the foreign national should visit the concerned jurisdictional FRRO/FRO and submit formal request for the service. The concerned FRRO/FRO will examine the request completely and if he/she prima facie agrees with the request of the foreigner, he/she will forward the application to the Ministry of Home Affairs for appropriate decision. If the concerned FRRO/FRO feels that the request of the Foreigner cannot be agreed to, he will straightaway advise the foreigner accordingly.
In case of any queries, Foreigners may contact Visa Support Center by email at email@example.com or on telephone numbers 011-22560198, 011-22560199
Comment: Seeing those rules and knowing Indian bureaucracy, I suspect processing time to get an additional entry in your one-year visa will be approximately 2 years...


Entering U.K. with expired passport but valid BRP and valid passport of other nationality

Question: So I am returning from a trip to Germany to the U.K. on September 10, but my Peruvian passport expires on September 7. My biometric residence permit is valid through the next three years, but because my passport is expired will I be refused entry? I am in the process of renewing my passport, but it is impossible to have it ready on time. However, I do have a valid passport under my American nationality. Would it be possible for the officer to stamp that instead or let me in anyway. I cannot cancel this trip, so if anyone has any solutions to helping me figure out solutions that will be very helpful. I plan to use the American passport to register with the airline so it will not be a problem for them to allow me to board my only issue is entering the U.K. again.
Comment: I don't have any authoritative sources to hand, but if I were going to do this, I'd travel both directions on the US passport. My feeling on this is it will probably be OK; after all, you are the resident, not your passport.
Answer: Your BRP is evidence of your immigration status in the UK https://www.gov.uk/biometric-residence-permits You will have to show it along with your valid national passport before you begin your return journey, and again when you re-enter the United Kingdom. The permit proves that you are allowed to return to the United Kingdom, but it cannot be used instead of a passport.
Since your US passport is valid, it is sufficient alongside your BRP.


Origin of the meaning of joe

Question: I knew that Joe was used to mean the average man, and I discovered that joe is used to mean also coffee.

What is the origin of such meanings?
When it is used to mean the average man, should I understand that Joe is/was the most common name?
Comment: I've always assumed that "joe", in the coffee sense, is derived from "java".
Answer: My Webster's lists joe as

coffee. [ORIGIN: 1940s: of unknown origin.]
an ordinary man : the average joe. [ORIGIN: mid 19th cent.: nickname for the given name Joseph; compare with Joe Blow .]

Etymonline concurs.
Comment: It seems interesting that Webster says the origin is 1940, and dictionary.com (to which Etymonline has a link for _joe_) reports the origin is 1840-1850.
Comment: @kiamlaluno: Look more closely. Webster's and Etymonline agree that the coffee meaning is from the 1940s and the "ordinary man" sense is from the mid-19th century. What's your issue?
Comment: I don't have any issues at all. [dictionary.com](http://dictionary.reference.com/browse/joe) reports that the origin of _joe_ to mean coffee is 1840-1850. As I thought I reached that page through a link on Etymonline (which is not what I did), I found interesting Etymonline would report a date, and have a link to a page that reports a different date. I didn't mean in any way to express a judgement about your answer. Still, I find interesting dictionary.com reports a different date.
Comment: [Etymonline](http://www.etymonline.com/index.php?search=joe&searchmode=none) has a link to the [Dictionary.com](http://dictionary.reference.com/browse/joe) definition of _joe_. The link is show in Etymonline as an icon placed after the word _joe_. Etymonline says the origin is 1941, and it links to another site that reports 1840-1850 as origin of the same word.
Answer: Michael Quinion at World Wide Words claims that the use of joe for coffee first appeared in print in 1930. He agrees it's of unknown origin, but outlines two of the more prevalent theories before concluding it's most likely a military-slang modification of other j-words for coffee:

It is significant that an early example appears in 1931 in the Reserve Officer's Manual by a man named Erdman: "Jamoke, Java, Joe. Coffee. Derived from the words Java and Mocha, where originally the best coffee came from".

The earliest print reference I could find was from Eugene O'Brien's 1937 naval novel He Swung and He Missed:
Answer: Seemingly NOT from the Secretary of Navy: http://www.snopes.com/language/eponyms/cupofjoe.asp
My personal guess is
java -> joe
http://www.etymonline.com/index.php?term=joe
"coffee," 1941, of unknown origin. Meaning "generic fellow, man" is from 1846, from the pet-form of Joseph (q.v.). Joe college "typical college man" is from 1932. Joe Blow "average fellow" is U.S. military slang, first recorded 1941.
Answer: 'Joe' as a representative name for a typical person of a given type
Use of Joe in what J.E. Lighter, Random House Historical Dictionary of Historical Slang, volume 2 (1997) calls "nonce expressions denoting a man who personifies or represents the specified quality, identity, or association" go back more than a hundred years. Examples cited by Lighter include the following (with date of earliest citation in parentheses: Joe Average (1936), Joe Balls (1945), Joe Blow (1924), Joe Brooks (1925, alluding to Brooks Brothers clothiers), Joe Buttinsky (1912), Joe Citizen (1986), Joe College (1932), Joe Cool (1949), Joe Doakes (1926, where 'doak' means a rube or a boob), Joe the Grinder (1939, aka 'Jody Grinder'), Joe Hep (1902), Joe Latrinsky (1918), Joe Lunchpail (1965), Joe Public (1941, but much less common than John Q. Public), Joe Sad (1929), Joe Schmoe (1950), Joe Six-pack (1977), Joe Union (1936), Joe Zilch (1925). Lighter reports that G.I. Joe first appeared in print in 1935.
The practice is clearly quite old. For instance, I came across an eight-page penny pamphlet published in England in 1819 and titled "A Few More Words to My Neighbours, written by an anonymous author using the pseudonym Joe Shrewd.

'Joe' as slang for coffee
Lighter's earliest citation for joe as a slang synonym for coffee is from 1930 in a dictionary of tramp and underworld slang. Nevertheless, Lighter says that the expression is especially common in U.S. Navy slang. Here are Lighter's first three cited occurrences:

1930 Irwin, Tramp & Und[erworld] Sl[ang] 110: Joe.—Coffee. 1931 Erdman Reserve Officer's Manual 441: Jamoke, Java, Joe. Coffee. Derived from the words Java and Mocha, where originally  the best coffee came from....Jilpot. Coffee pot. A corruption of "joe-pot." 1933 Leatherneck (Mar[ch]) 27: He observed that more is learned in a "jo" party than in any class instruction, so "coffee and" rank marksmanship problems after all.

Also of note is this citation from 1980, which seems rather far-fetched, but which Lighter suggests may be relevant, given the fact that "the Foster song was extremely popular":

1980 Mack & Connell Naval Trad[ition]s (ed. 5) 260: Some sailors call coffee "joe," which some say is a derivative of [Stephen] Foster's song, "Old Black Joe."

Godfrey Irwin, American Tramp and Underworld Slang (1930) provides the following full entry for joe:

JOE.—Coffee. Probably a contraction of "jamoke."

As for jamoke, the same book has this:

JAMOKE.—Coffee, and without a doubt from the two words indicating the sections of the world, Java and Mocha, from which much of the coffee comes.

On the other hand, according to Irwin, jamake (or simply jake) refers to "Jamaica ginger, used as a beverage and much favoured by the older tramp and more hardened drinker, but practically impossible for the average man to stomach."
The full name of the second source that Lighter cites is Robert Erdman, Reserve Officer's Manual: United States Navy. The 1932 edition of this book includes the quoted entries for "jamoke, java, joe" and "jilpot" in a section called "Naval Terms." Interestingly, although Erdman derives jilpot from joe-pot, Anthony Lawlor, Irish Maritime Survey: A Guide to the Irish Maritime World (1945) includes a listing for jilpot ("a seaman's term for the teapot or coffee pot") and jamoke ("a seaman's name for coffee. It is a corruption of the words Java and Mocha, places where it was once thought only good coffee could be obtained"), it doesn't mention joe.
Bolstering the notion that joe derives from jamoke is the fact that jamoke appears in print earlier than joe (in the sense of "coffee") does. From "Where Justice Sleeps," in  the [Anamosa, Iowa] Reformatory Press (May 6, 1911):

During the morning, the marshal brought them some "red gut," "punk," and "jamoke." At least that was their language later on when describing their meal. Perhaps some of my readers understand this slang. I do not.

I haven't been able to identify what "red gut" referred to in 1911 reformatory slang, but "punk" referred to bread, and "jamoke" to coffee.
From The Lucky Bag (U.S. Naval Academy, 1924):

We got on speaking turns with swabs, squilgees, kiyis, buckets, slice bars, dogs, paintwork rags, salt water soap; we learned who said, "Coming through dirty" and "Let's swap backs"; we corroded our sides with "jamoke"; we became adept in in the art of washing from a bucket; we sought diligently for new and secure places to caulk and sometimes succeeded; we accustomed ourselves to canteen skags; we aired bedding and held quarters; we damned and blessed in the same breath,—but we learned.

From an advertisement for Sir Walter Raleigh pipe tobacco in The Leatherneck, volume 13 (1930):

And how!! Don't blame old Slumburner for heaving you out when you smudge up his galley with a pipe that smells worse than a Shanghai alley. Break off being an eight-ball. Swab out that ripe crusted old briar, stoke 'er hold with Sir Walter and put yourself in right for  good hot cup of Jamoke from the cook.

And from Les Voyageurs Annual, volume 21 (1930, University of Michigan) [combined snippets]:

A cup of excellent "jamoke"; the rich, golden, nut-brown smell of pipe smoke; the crackle of the fire; and then the good old sing, in which everybody joined. Outside the snow was piling up, and at twelve o'clock it was shoe-top deep.

However, there appears to have been a rival sense of jamoke in use Arizona during the early 1920s. From "Dug Their Way Out of Miami 'Hoosgow'," in the [Flagstaff, Arizona] Coconino Sun (January 16, 1920):

Two strange drunks were picked up in Miami, with their pockets stuffed with bay rum, the inspiration of their jag. They were locked up in the calaboose. The deputy failed to notice that a new concrete floor had been laid in the cell and that it was still soft. Sometime after his departure the prisoners dug the soft concrete out from under the door and crawled to liberty. They are likely on their way to Mexico by this time. The district is rid of two "jamoke" fiends and the taxpayers are winners to the amount of one trial and subsequent feeding of the prisoners.

From "Jamoke Ginger Not Intoxicant Unless Sold as Beverage" in the [Phoenix] Arizona Republican (November 25, 1920):

Jamoke Ginger Not Intoxicant Unless Sold as Beverage
BOSTON, Nov. 24.—Unless Jamaica ginger is sold as a beverage, it i not to be considered as intoxicating liquor, the full bench of the supreme court tody ruled in setting aside verdicts of guilty in the case of Sam Soakey and Michael J. Reagen, store keepers in Pittsfield.
Judge DeCourcey held that the sale of Jamaica ginger as a disguised substitute for liquor "is not so notorious  that e can assume without proof that Jamaica ginger has the distinctive character, use and effect of an intoxicating liquor."

From "13 Faints Is Limit for Shocked Ones at Snake Ritual," in the [Prescott, Arizona] Weekly Journal-Miner (May 25, 1921):

Looking over the collection of snakes which have been attracted to the Owl Drug company window by the stock of "Jamoke" and perfume kept there for medicinal and society uses, Van Dickson confided to David H. Biles, of the Biles-Lockhart Clothing company that the exhibition to be held in the county seat was far enough west to have the real thing in snakes used in the performance, and he regretted having made an untimely end to a huge rattler with which he played a few days before tiring of the friendliness of the button-tailed monster.

These three instances suggest that jamoke referred to an alcoholic preparation similar to bay rum intended for external use and perhaps owing its name to a corruption of "Jamaica ginger." They also seem in line with the entry for jamake in Irwin's 1930 book of tramp and underworld slang.
With regard to the U.S. Navy connection to both jamoke and (supposedly) the Stephen Foster song "Old Black Joe," I note that Andrew Pendlton, The Silly Syclopedia: Containing "Daffynishuns" of the Words of the Slang Spoken by the Midshipmen of the U.S. Naval Academy (1908) reveals that then-current slang term for a black servant, especially on e working in the Naval Academy's mess hall, was moke:

MOKES—(From the Spanish Mozo meaning servant.) The sons of Ham with waiter's billets.

Elsewhere in the book, Pendleton offers this bit of doggerel:

M is for the Moke who you must implore/ And never order, as it makes him sore/ To bring you grub/ Aye there's the rub/ For invariably he says, "Tain' no more!"

Lighter finds instances of this offensive term for a black person from as far back as 1847, so if there were a connection between moke and jamoke, it would have moved from the pejorative term to the beverage (a similar path to the one claimed in the case of "old Black Joe" being shortened to joe).
Recent dictionaries do not agree on the origin of joe in the sense of coffee. Merriam-Webster's Eleventh Collegiate Dictionary (2003) has this:

joe n {perh. alter. of java} COFFEE

but the American Heritage Dictionary of the English Language (2010) has this:

joe n. Informal Brewed coffee. {Short for (old black) joe, military slang for coffee, from the title of a song by Stephen Foster.}

I would be more inclined to think that the AHDEL's etymological suggestion is plausible if I could find any instance of the term "old black joe" used for coffee in the decades before 1930. But after considerable searching in Google Books and the various Elephind newspaper databases, I couldn't find a single one. To my mind, the Java + mocha source of jamoke, followed by a shortening to joe, represents the simplest path consistent with the order in which jamoke and joe entered slang usage.
Answer: Some name must be chosen to fill the role. Tom, Dick and Harry lend a hand too, not to mention John Doe.
"Average Joe" is a phrase (limited in age by the prevalance of algebra education?) but can the term "Joe" be used alone in this sense at all?
Comment: @Kiam: It is not used with "average," but neither is it used alone. It is an idiomatic phrase.
Comment: In _Joe Sixpack_, the word average doesn't appear.
Comment: No, because by itself it's just a name, it needs some sort of adjective or descriptor to signify it's being used in a more abstract sense.
Answer: I believe Joe came from Spanish or Latin-American languages. The latest borrowed it from ancient Slavic word pronounced very similar both in Spanish and Slavic languages.
Comment: They are probably only concerned with modern English here, not about its derivation or Sanskrit roots.
Comment: @PerformanceDBA, I infected you with non-DBMS and non-6NF areas?
Comment: More "activated" a latent interest, rather than "infected" which is introducing something that was not there. Generally, yes.
Comment: @GennadyVaninNovosibirsk - Are you trolling with this answer?  The OP asks why coffee is "joe", and you explain that it comes from the rudest word for "penis"?  Tell me you're not serious.

Origin of the meaning of joe


Does cashing out 401k interfere in unemployment

Question: If I cash in my 401k do I have to log that as earned income on my weekly unemployment filing in Arizona. I had no choice since $160 per week does not pay my bills. I used it to pay off my car and a credit card to alleviate the financial load.
Comment: Yes, some states reduce unemployment payments when there is 401k income, a quick search suggests that AZ is one of these states.
Comment: Have you already cashed it out?  I would probably have sold the car before paying 50% tax/penalty on a 401(k) cashout.  I would STRONGLY consider trying to make a contribution to avoid the penalties if there's any feasible way to do so.
Comment: I agree with DStanley. Far better to sell the car and use that to make CC payments.  Because your emergency fund was not fully funded, you should not have had a car note, much less credit card load.  Now is the time to take whatever job you can (fast food, delivery, Walmart, etc.), as a bridge job, while you look for a new, full-time, career track job.
Comment: @DStanley: for someone unemployed and struggling to make a car payment I doubt the marginal rate is above 25%+state plus the 10% penalty. You can't recontribute to a 401k when you're not earning pay, although you could open or add to an IRA within 60 days and treat it as a rollover.
Comment: @DStanley Early disbursements are penalized by 10%, and add to your taxable income (another 10-25% of the disbursement).
Comment: @Xalorous Fair enough, so 10% penalty, 15% fed tax and 3% AZ state tax. 28% in taxes in penalties still make it a bad idea except if completely desperate.
Comment: @DStanley I had a 401k loan which (complicated story) became a disbursement and resulted in me owing 2400 in penalties and taxes on roughly 7400 of unrepaid loan.  So for me it was closer to 33%.  So 401k loans may sound good, but one should make sure the repayment period is short and be able to repay on short notice.
Answer: It depends on your state's unemployment rules.  But it appears that AZ will reduce your employment benefits if you take out money from your 401(k).  The advice in the link is to wait until you have exhausted all of your benefits before drawing on your 401(k).
https://www.justanswer.com/employment-law/7lnb9-arizona-unemployment-laws-i-laid-off-year-downsized.html
However, given the financial hardship you are under, it may make financial sense to clear out sources of high interest debt such as a credit card or car as these could outweigh any benefit you may gain by paying the minimum credit card payment, and pushing back on auto loan payments.  It would also give you some peace of mind.
As the benefits vary based on the amount of your 401(k) withdraw, it is important that you keep the withdraw to the minimum.
Answer: Under the CARES act there is no penalty and you have three years to pay the federal taxes or to put the money back without penalty.  Just make sure you withdraw with a direct cause relating to the Coronavirus.
Just realized this was an old post not related to the Coronavirus
Comment: Plus it was about the effect on _unemployment insurance_ (aka unemployment benefit), not on taxes. And as stated in past comments and answer, unemployment (in US) is run separately and differently by each state, not federally.


Mac-sforge motivation for storing pairs

Question: I don't understand why Q keeping pairs of  instead of m like mac-forge solves the problem of generating a new tag on a previously authenticated message. Say, a previously authenticated message for "Cat" is tag 90, Adversary can retrieve (Cat, 90) from the query. However, if Adversary is able to successfully forge a new tag (Cat, 138), I almost feel as if sforge weakens the definition. Q has Cat, but it doesn't have 138 as the tag, so this will pass mac-sforge, but not pass mac-forge. Could someone clarify my confusion?
Relevant passage From Katz and Lindell:
"As defined, a secure MAC ensures that an adversary cannot generate a valid tag on a new message that was never previously authenticated. But it does not rule out the possibility that an attacker might be able to generate a new tag on a previously authenticated message. That is, a MAC guarantees that if an attacker learns tags t1, . . . on messages m1, . . ., then it will not be able to forge a valid tag t on any message m ̸∈ {m1, . . .}. However, it may be possible for an adversary to "forge" a different valid tag t′1 ̸= t1 on the message m1. In general, this type of adversarial behavior is not a concern. Nevertheless, in some settings it is useful to consider a stronger definition of security for MACs where such behavior is ruled out.
Formally, we consider a modified experiment Mac-sforge that is defined in exactly the same way as Mac-forge, except that now the set Q contains pairs of oracle queries and their associated responses. (That is, (m, t) ∈ Q if A queried Mack(m) and received in response the tag t.) The adversary A succeeds (and experiment Mac-sforge evaluates to 1) if and only if A outputs (m,t) such that Vrfyk(m, t) = 1 and (m, t) ∈/ Q.
DEFINITION 4.3 A message authentication code Π = (Gen,Mac,Vrfy) is strongly secure, or a strong MAC, if for all probabilistic polynomial-time adversaries A, there is a negligible function negl such that:
Pr[Mac-sforgeA,Π(n) = 1] ≤ negl(n)."
Answer: A security definition is stronger if we make it easier for the attacker to win. The point being that the stronger definition rules out even this easier way of winning
In the specific case noted in the question, you are indeed correct.
The scenario you describe is the following:
An attacker queries "Cat" and receives the tag "90". It then computes the tag "138" such that $\mathsf{Vrfy}_k(\text{Cat},138)=1$ and outputs the pair $(\text{Cat},138)$.
The regular $\mathsf{MAC\text{-}forge}$ experiment will reject this output. I.e., the attacker does not win, and therefore this security definition does not rule out the existence of said attacker.
The stronger $\mathsf{MAC\text{-}sforge}$ experiment will accept this output. I.e., the attacker wins, and therefore this security definition rules out the existence of said attacker.
Comment: Thank you this definitely helps. So stronger definitions in general make it easier for the attacker to win? My only confusion with this is the quote the book uses "Nevertheless, in some settings it is useful to consider a stronger definition of security for MACs where such behavior is ruled out" (114). This makes it sound like it does make it secure because it is ruling out the possibility of reauthenticating a previously authenticated message with a different tag.

Mac-sforge motivation for storing pairs


Subpanel wire size questions

Question: I am installing a subpanel in an out building that will be fed from a 50 amp subpanel in another out building ( going all the way to the main box is not an option). I only need 30 amps in the new bulding and I am using #6 wire for the 80' run between buildings. After the new subpanel and a 30 amp breaker will be another 55' run to a 30amp plug for a RV hookup. According to the interwebs I can use a #10 wire for that run. My question is when I'm calculating wire size is the length of the run considered from the new breaker to the outlet or do I need to use the distance from the original subpanel in the other building ? My thinking is I should use #6 all the way to the outlet as well.
Comment: The National Electrical Code recommends (does not require) a maximum voltage drop of 5% between feeders and branch circuit to the outlet, and a maximum of 3% on the highest one of the two. Either feeder or BC. Calculate and wire accordingly.
Answer: You have 2 completely different questions in two completely different scopes. Don't confuse them.  You must consider and answer each individually, and use the higher of the two answers.

Given the receptacle you want to use, which defines the breaker size, what is the minimum wire size you must use to keep from cooking the wire?   A 30TT or 14-30 requires a 30A breaker, and the answer is "10 AWG wire".
Given the current you realistically expect to draw, actually, how much voltage drop do you feel will be acceptable to you?   This is more complicated, starting with the "current draw, actually".  It depends dramatically on what appliances are installed in your RV, which appliances you actually do use, and how much current those draw. Which you need to survey.

Remember -- having a 30A plug does not mean the RV draws 30A.  It means that is the standard socket at RV parks, because some other RVs draw 30A.
Continuing part 2, you need to figure out the voltage drop you find acceptable under your practical load(s).  I for one don't have a problem with a 5-6% drop, but then, I don't feed my family by upselling you into thicker wire.  Those who do, say 3% is max.   3% is not mandatory, it boils down to what you find acceptable.   The voltage drop cannot damage your wire, the required breaker in step 1 guarantees that.
As an example, let's say your practical load is 10A most of the time and you'd like to have a 3% drop then; or 20A in extreme circumstances and you don't mind a 6% drop then.
Plug those into a voltage-drop calculator, and there you go.  (only consider the distance from the last subpanel to the RV).
Now, take the largest (smallest numerically) in step 1 (10AWG) and step 2 (in my example 12AWG).  You must use at least 10AWG.
If you did the numbers again with 3% at 24A (the highest you are likely to draw continuously), I get 10 AWG.
If you want to for thicker wire nonetheless, that's between you and your wallet.

Now consider the new AA-8000 aluminum alloy wire.  The ooga-booga about it never applied to AA-8000, nor to large conductors.   At those large sizes with lots of metal content, it is far cheaper, and bonds better to large lugs, which are made of aluminum.
Starting at 6 AWG Cu, I start pricing it both ways - you need to run the numbers and typically go up a wire size i.e. 4 AWG Al.  For the cost, you could even upsize the AL and reduce your voltage drop further.
If you upsize the feed to a subpanel, you can upsize the supply breaker.  If you upsize the feed to a receptacle, you must use the breaker the receptacle requires.
Answer: "My question is when I'm calculating wire size is the length of the run considered from the new breaker to the outlet or do I need to use the distance from the original subpanel in the other building ?"
For voltage drop calculations, the whole wire run, from the main panel, will see voltage drop along the way. But because the upstream wire size is bigger, it will not contribute as much to the voltage drop as the last section.
I recommend you put the largest wire you can afford & is practical to handle.Someone down the road will thank you. You can have a 30A breaker protect a #6 wire feeding a 30A receptacle. A few years from now you might want to have a EV charger there and you'll be happy to already have the appropriate wire installed.

Subpanel wire size questions


Is the covariance matrix the equivalent of standard deviation for a 2d matrix?

Question: I want to measure the scale of a 2d matrix that contains the coordinates (x,y) of a set of point. I know that the standard deviation of the x coordinates of these points is the scale of the x coordinates, and the same for the standard deviation of the y coordinates. I looked for a way to calculate the standard deviation of the whole matrix but apparently the standard deviation is defined for 1d vectors only. But I noticed that some people use the square of the norm of the covariance matrix as a scale. Does that mean that the covariance matrix is the equivalent of the standard deviation, but the latter is defined for 1d vectors while the former is for 2d matrices? Is there another way to calculate the scale of a set of points?
Comment: I'm not sure if this is quite a duplicate, but you might want to read: [Dispersion of points on 2D or 3D](http://stats.stackexchange.com/q/189102/7290), & [2D analog of standard deviation?](http://stats.stackexchange.com/q/13272/7290)
Comment: @gung, thank you for the pointing me to that post. It answers indeed my first question, but I still need an answer for the second question (regarding the other ways of calculating the scale of a 2d matrix).
Comment: I linked to 2 posts. Between them, they list 3 possibilities. Can you clarify what you still need to know?
Comment: "Dispersion of points on 2D or 3D" is the one that answers my first question.
Answer: Short answer: The covariance matrix is the multidimensional analog of 1-d variance (which is itself sd^2).
Some authors have even referred to the covariance matrix as the variance-covariance matrix, or even simply the variance where the dimensions are implied from context.
If you are looking for scale specifically, you could get the square roots of the eigenvalues of the covariance matrix which will be the standard deviations along the principal components. For this interpretation see https://math.stackexchange.com/questions/23596/why-is-the-eigenvector-of-a-covariance-matrix-equal-to-a-principal-component. The "volume" of your covariance matrix can be found by the square root of the product of these eigenvalues, which is also equal to the square root of the determinant of the matrix.
Alternatively, you might consider the Cholesky decomposition as a method to get something similar to a multivariate standard deviation. This concept is often seen when generating random variates from a multivariate normal distribution and the resulting lower triangular matrix is used essentially in place of the univariate standard deviation. See here for more details: Can I use the Cholesky-method for generating correlated random variables with given mean?
Answer: You may find other answers easier to find if you change your terminology: when you have a collection of zero-dimensional values, you can measure its dispersion by taking the variance or the standard deviation. If you want to store them all, then it probably makes sense to stuff them into a one-dimensional vector, but you could just as easily have a two-dimensional collection, for example, the pixels in an image. The point is: the things whose dispersion you're trying to measure are each just numbers, zero-dimensional objects, so you can use the standard deviation or the variance.
If you have one-dimensional things whose dispersion you want to measure - for example, you have a bunch of objects and for each one, several measured quantities - then you need something more than just a variance. The natural generalization is the covariance matrix, because you need information about not just how much each thing varies, but about how they vary compared to each other. So if you have a bunch of one-dimensional things, you describe their variance with a two-dimensional matrix. Again, you might or might not put the things in an array (which would be at least two-dimensional, but might be more, for example if you were looking at the R G and B channels of an image).
What if you have a higher-dimensional thing and you're interested in dispersion? A bunch of matrices, perhaps? Well, now you run into notation and bookkeeping headaches. Really you should be getting higher-dimensional analogues of matrices, tensors, but these are usually awkward to work with, so usually you "flatten" your matrices into vectors and just take the covariance matrix again, "unflattening" as needed.
My point is: there are two separate notions here, how you organize the collection of things you're trying to summarize statistically, and what the dimension of each thing is. A variance or standard deviation is something you do to (a lot of) just-plain-numbers, while a covariance matrix is what you get when you have (a lot of) vectors.


What do I need to shoot with a wireless speedlite and my Nikon DSLR?

Question: I planning to buy a Speedlite for my camera Nikon D90. I want a speedlite that can be triggered remotely using wireless, as well as mounted on camera. Can someone help me on what all I need to buy? The speedlite, something to trigger the speedlite remotely, some sort of mount for the speedlite — and anything else?
Comment: As it stands this question is way too broad. Any definitive answer that covers *everything* you might have missed would be book length. While we *don't* do product recommendations ("What should I buy?"), we *do* have plenty of questions that go along the lines of "I'm thinking of using flash *x* with camera *y*. Will using trigger *z* allow me to fire/remotely set power and zoom manually/use TTL/use HSS/use second curtain sync/use FEC-FEB?"
Comment: See [the Strobist's Lighting 101: Ideal Beginner's Kit](https://strobist.blogspot.com/2006/03/lighting-101-traveling-light.html); [What features should one look for when selecting a flash?](https://photo.stackexchange.com/questions/17722); and [What should I look for in a wireless flash trigger for a home studio?](https://photo.stackexchange.com/questions/57653)
Comment: Sounds like you have figured out the basics that you need (speedlite, something to trigger the speedlite remotely, and mount for the speedlite). Are you looking for specific suggestions for particular models of those things to buy? If so, please understand that shopping questions are off-topic here at Photo.SE.
Comment: Thank you. I am not looking for specific model. I wanted to know if there is any other part I am missing.
Answer: There are only a few possible ways to trigger a remote flash.
And only a speedlight will have the foot to mount on camera in the hot shoe.
Maybe see http://www.scantips.com/lights/flashguide.html

Your D90 has a Commander in its internal flash that supports Nikons wireless method.  Several Nikon flashes can do this, SB-700, SB-900, older SB-800 and SB-600.  A very few other cases can do this too, like Yongnuo YN-565EX. This method includes TTL flash mode, and works pretty well indoors, less so outdoors.  It uses infrared signaling, and requires clear line of sight between camera and flash.
Radio triggers will work, attach a transmitter on camera hot shoe and receiver on flash foot.  This pretty much works anywhere. It will generally be manual flash mode only, but there are alternates.
Optical slave. Some speedlights build one in, some require adding an inexpensive attachment to the flash foot.  This is manual flash mode, and are triggered in sync by seeing any other manual flash, like for example, the cameras internal flash can be a trigger.
PC sync cords are old standby, a cable from camera to flash.  For cameras without PC connector, and for flashes without PC connector, adapters can be added to provide it.
Comment: Radio triggers car be TTL compatible or manual only. Manual will work on any camera brand, whereas TTL has to be compatible with the proprietary protocol/wiring. The difference is the price.
Answer:
I want a speedlite that can be triggered remotely using wireless, as well as mounted on camera.

Any speedlight with an ISO-compliant foot and a sync voltage between 0-250V will fire in sync on a Nikon dSLR hotshoe, and can be triggered remotely with hotshoe-fitted radio triggers. However, if you want more advanced capabilities, like HSS/FP or iTTL, etc. you will need a flash that is Nikon-compatible, and that has the correct pin configuration on its foot to match the contacts on your camera's hotshoe. (See: Are Yongnuo flashes interchangeable between dslr's or are they brand specific?).
If you want to use CLS, you need a flash that has a CLS slave sensor in it. If you want "dumb" optical slaving, you need a flash that has that built-in, or has a way to attach that type of optical slave (PC sync port, flash foot).
See also: What features should one look for when selecting a flash?

Can someone help me on what all I need to buy? The speedlite, something to trigger the speedlite remotely, some sort of mount for the speedlite — and anything else?

Most typically, a one-light Strobist setup includes the following:

Speedlight
Light stand
Umbrella swivel/adapter (to attach the flash to the light stand)
Radio trigger (transmitter on the camera; receiver on the flash)
Modifer (umbrella, softbox, whatever), optional

The modifier is optional, but the light will typically be hard light without it, unless you're bouncing the flash.
Radio triggers are the most common form of wireless flash triggering used, because they don't have the line-of-sight requirements that optical triggering typically does.
Keep in mind that radio triggers, like optical systems and sync cables, also come in manual-only and TTL/HSS/remote-power control flavors.  The more features the triggers have, the more expensive they're liable to be, but also the more convenient. (See also: What should I look for in a wireless flash trigger for a home studio?).


Did the Hayate no Gotoku anime adapt the manga closely?

Question: I'm gonna start watching Hayate no Gotoku anime and I haven't read the manga so I need to know whether the anime adapted the manga closely. I am referring to all of the anime seasons and movies .
Comment: Which season are you watching? There are quite a lot of anime-original content in the first season (but they are still canon, IIRC), 2nd season sticks to the manga, 3rd season is something entirely new, ahead of the current story in the manga (still canon?) and 4th season follows the manga, except for the last 2 episodes (not sure whether they are canon).
Answer: As nhahtdh pointed out, the first season has a lot of original content of the manga, but the time scale is completely different. Inside the anime, the first season was equivalent to more than a year, however in manga only 9 to 10 months have passed till then.
The second season completely sticks to the manga. So it does not seem like a continuation of first season.
The story of the movie: HnG Heaven is a place on Earth is not at all related to manga and so is the third season. However, the story of the third season was written by Hata Kenjirou (the Mangaka of HnG).
The new characters introduced in third season are present in manga, but the story is completely different. The fourth season HnG Cuties is a series of 12 episodes. The first 10 episodes are based on discrete chapters of manga. Each dedicated to some character(s). The last two episodes are not in manga.
Overall, you should give it a try!


Appliances plugged in GFCI outlet works but when plugging in the downstream outlet doesn't

Question: When I plugging coffee machine in the GFCI outlet, it works but does not in the downstream outlets. The Voltage of downstream outlet drops to 87V after plugging in the downstream outlet.And shows open neutral if plugging tester. GFCI wasn't tripped and voltage was still 120V.
Test-reset GFCI will bring the Voltage back. Any suggestions to troubleshoot?
Comment: As @Barry notes below, its sounding like you have a bad connection at the GFCI or downstream. Backstabs (if used) are a "feature" that should not be used. Please ensure all wiring is sound, no cuts, breaks or otherwise. Make sure your wirenuts are tight and properly installed. You may even have to replace the outlet. CHECK BOTH ENDS *(the GFCI as well as downstream)
Comment: @noybman I can follow your comment better than the answer Barry provided. I agree it is a loose connection that has a problem under load. I also have a love / hate for backstabs, they have made me tens of thousands over many decades. I think they should be illegal but are "safe" when installed to code. I can give your comment an upvote + and the question as it is well defined+
Answer: Only do the following if you are familiar with electric wiring and the necessary safety precautions.

Switch off the circuit breaker that controls the outlet with the GFCI.
Open the outlet and remove the GFCI.
Check the wiring.

There should be two wires (black and white) going to the terminals marked LINE.  There should also be two wires (should be black and white) connected to the LOAD terminals.  The hot wires are black and the neutral wires are white.
If these check out, and if you think you are prepared, then switch the breaker back on and check the voltage at the LINE terminals (should be about 120 V).
Then check the voltage at the LOAD terminals (should be the same voltage).
Push the TEST switch on the GFCI.  The voltage at the LOAD terminals should
 go to 0 V while the voltage at the LINE terminals should stay at 120 V.
If all of this checks out, you need to check at least one of the downstream outlets. Again, they should have a black and white wire connected to their terminals and the voltage should be 120 V.
Trip the GFCI and check that the voltage goes to 0 V.
Note that if any of the connections use the backstab (located at the back of the outlet), you should change those to connect with the screw terminals on the outlet. Backstab connections are known to be unreliable.
If everything checks out, then you may need to call an electrician.
Comment: A suggestion to help this answer get the vote it deserves, please break this into some bullet points or at least paragraph separated as it is a bit rough to follow right now. I'd personally suggest he not apply breaker power until each outlet is checked from A-->b-->C etc. and ideally, a problem has been found and fixed.
Comment: Don't put spaces in the fronts of your lines, it causes weird formatting.  You also need two newlines (a blank line) if you want a paragraph separation.  Please take the time to learn SE edit formatting; there are help links in the edit window.  If you are copying content from elsewhere and it's coming in this way, don't copy content except in attribution.
Comment: @Harper Thanks for the tips.

Appliances plugged in GFCI outlet works but when plugging in the downstream outlet doesn’t


After rebooting motorola defy M525 no service network shows?

Question: After several attempts of pattern my motorola defy mb525 has been blocked and asking for my goggle account and password but then when finished entering my account and password it will restart automatically but the problems is still there.. So i tried to reboot my motorola defy mb525 but after rebooting, the service network is gone. No more signal in any GSM network...Please somebody help me about this problem. how can i fix it?
Answer: Try calling your service provider. Some cell companies lock the phone after failed attempts as a precaution to possible theft.
Comment: ok thank you for your idea but my simcard if i inserted it to other mobile it has service network only in my motorola defy after rebooting.


Density Matrix and Resolving the Identity

Question: If I have an ensemble distributed evenly among k states, I have k states {$|\psi_i \rangle$} where i$\in$ {1,...,k} with equal probabilities
$$p_i = \frac{1}{k}$$
Defining the density matrix,
$$\rho = \sum_{i=1}^k p_i|\psi_i\rangle \langle \psi_i| = \frac{1}{k}\sum_{i=1}^k |\psi_i\rangle \langle \psi_i|$$
My question is, can I say that the sum above is equal to the identity operator? Does the density operator only act on states within the ensemble or can it act on any state? Why do we even use such an operator (I.e. What is it's usefulness)?
Answer: The density matrix is not really an observable and we rarely "act" with it on states . It is another representation of the state of the system which is also capable of handling statistical mixtures of states.
This is exactly the case here: Your state is randomly drawn from a number of states. You can't represent it by a vector in Hilbert space (those are only "pure states"). But you can do it using a density matrix - the one you wrote above.
Everything you usually do with a state vector, you can also do with the density matrix. For example, the expectation value of an observable $A$ given the state $\rho$ is given by $\mathrm{Tr}(\rho A)$. The Shrödinger equation is replaced by the von Neumann equation, etc.
Finally, $\rho$ is not neccessarily the identity. In fact, you can show that it's the identity if and only if the $\rho_i$ are an orthonormal basis.


Poly .wav picture editorial <-> sound dept workflow questions

Question: Hi guys, so, I'm about to be using a Sound Devices 788T on set and I know I'm going to want to run at least in 4 track mode. What I'm mainly curious about is the production sound -> picture edit -> sound edit workflow. I keep hearing people talking about doing the mono mix for the picture editor. Is there some way that the picture editor can just be given the mono mix, dialogue editor is delivered production sound files, and then is able to reconform the entire multitrack polywave easily? Does the timecode stamp on the sound file take care of this?
Answer: It is fairly common for a production mixer to deliver a mono mixdown of tracks to the editor as a temp guide track for picture cutting purposes. Especially if you're recording say more than 4 channels of production sound on set. Multiple channel production sound can easily become unwieldy in the Avid, and some picture editors (depending on working style) don't like to deal with 8 tracks of dialog in their timeline (which can easily become 16 if they like to overlap dialog). This method of workflow is usually determined on a show to show basis.
The sound department receives the multichannel files and conforms them to the mono mixdown cut by the picture department using tools such as Conformalizer, Virtual Katy, or Titan. Sometimes even just by hand syncing (which I've done and is a total pain). This requires an EDL from the picture department and proper timecode stamps from the production mixer to work. Then the dialog editors can work their magic using split tracks.
This process can be easily messed up if the tracks aren't properly labeled, timestamped, or imported incorrectly; so it's very important to run a test between the picture and sound department with one scene early in the process to make sure everything is working correctly.
Answer: So:

Make sure your mixdown track(s) is always the same for the whole project (usually 1, or 7+8, or 1+2)
Deliver your original multitrack audio to the editor and sound department

The assistant editor will

import the audio
create synced subclips for edit using only the mixdown track(s), but the other tracks will still be easily available through "match frame" if needed during edit.
export an AAF for sound when the picture edit is done.

The sound department will import the AAF, and relink all audio to the originals.
As Justin P mentioned, this workflow, while very standard, should still be checked in advance to make sure there isn't a small mistake somewhere which might prevent easy and automatic relinking.
Answer: Hi James.
You definitely DO NOT want to give a mono mix to anyone (assuming by mono mix you mean a sum of your 4 discrete audio tracks).  You will hand over all of your discretely recorded tracks to the picture editor.  He/she will then sync these tracks to picture, edit the film and hand it to the sound editor to select the appropriate track(s) for the re-recording mixer.
Each individual track that you are recording is in mono (duh) so that's maybe what people are referring to.
Comment: lots of offline editor's working here like to cut with the mono mixdown, and simply mute all the other tracks while they're working (but not delete them!... usually....). Quite common for TV because of how fast those guys are cutting
Answer: Depending on the requirements of the film, i.e. if you screen dailies, you may or may not be required to do a mix. Tim Prebble's answered this before here. I reckon it is part of the production sound mixer's job to mix the tracks down to help save time for post production. If it's no good, then the dialogue editors can use the discreet tracks.


Fantasy book from my childhood: female protagonist, Blood Ore or Blood Metal for taking attributes

Question: The series I remember is about a young female lead.  She is in a world where human trafficking is common.  The rich and powerful are able to take another person's attributes through the use of a Blood Ore or Blood Metal.  The female protagonist doesn't join the practice, but rather eats the brains of large insectoid creatures to gain supernatural abilities.  The human inhabitants are fighting each other, ignoring the looming threat of giant deep earth dwelling insectoids.
Comment: Welcome to the site! Can you add any more details about this book - how long ago did you read it (we don't know when you were a child)? was it new then? roughly how many books in the series? was it for younger kids or "young adult"? was it written in English or another language? what sort of "supernatural abilities"? anything else about the plot?
Answer: Probably the Runelords series by David Farland.
The rich and powerful are able to take another person's attributes through the use of a Blood Ore or Blood Metal.

The main magical system of the series relies on a system of attributes which are inherent to every living creature. These attributes are transferable to and from both man and animal, so brawn from a dog can be transferred to a man. Once an individual gives an attribute to another, the giver loses that particular attribute until the death of the recipient. Each person can only give one endowment in their lifetime. Endowments include brawn (physical strength), grace (physical dexterity), wit (memory and clearness of thought), metabolism (speed at which the body's processes operate), glamor, voice, stamina, sight, hearing, smell, touch, taste, talent, will, bloodlust, and pain. [...] Endowments are transferred with special tools called forcibles. A forcible is cast of a rare material called blood metal into the rune corresponding to the endowment to be transferred.

The human inhabitants are fighting each other, ignoring the looming threat of giant deep earth dwelling insectoids.

Reavers are a massive species of subterranean creatures which bear no resemblance to any surface dwelling creature. Reavers are somewhat like insects, communicating through scents and having various "castes" which perform different functions within their "hives", though they do not have a collective intelligence. They are unchallenged masters of the Underworld.

The only part which I can't find a fit for is the female protagonist. From Wikipedia it seems that both the Earth King series (first four books) and the Scions of the Earth series (fifth to eighth books) have main protagonists who are male: Gaborn and Fallion respectively.
Comment: I misremembered the protagonist's gender.  You found the book, thank you very much!


Show submitted form input without server-side scripts

Question: Is there a way to accept form input and have the output dumped/printed back to the web page with HTML or JavaScript/AJAX and without PHP/Perl/server-side scripts?
Comment: A minor point, but "ajax" includes a server-side technology like PHP or Perl. Ajax is part client (eg. JavaScript) and part server.
Answer: Off the top of my head, you could do something like...
<form class="dump" action="#" method="post">
<fieldset>
    <legend>Dump inputs</legend>
    Name
    <input id="name" type="text" size="25" />
    email
    <input id="email" type="text" size="25" />
    <input type="submit" id="submit" value="Send" />
</fieldset>

and then a bit of JavaScript (I'm using jQuery, but I'm sure you can do this with normal JS). This will fire when the form is submitted, creates vars from the values and then output them to the screen (after the bottom of the form)
$(document).ready(function() {
$('form.dump').each(function() {
    $(this).children('fieldset').children('input#submit').click(function() {

        //Clear any previous outputs
        $(this).parent('fieldset').parent('form.dump').siblings('.output').remove();

        //Create the value vars
        var nameVal = $(this).siblings('input[id="name"]').val();
        var emailVal = $(this).siblings('input[id="email"]').val();

        //Output after form
        $(this).parent('fieldset').parent('form.dump').after(
            '
Name is ' + nameVal + '
' +
            '
email is ' + emailVal + '
'
            );
        return false;//Stops browser trying to actually submit the form
    });
});

});
Of course, there are a few things to bear in mind

Make sure there's a suitable non-JS fallback
This does nothing with the data except output it back to the page
This does no validation/sanitizing etc
There may well be a leaner/better way, but it's Monday morning and this is the first thing I could do off the top of my head ;o)
Answer: Displaying form results with HTML and CSS only
It's possible to display form results using only HTML and CSS with clever use of the :target selector. An explanation is below the code.
Click for a live demo. (Type in the box in the 'Result' window and click "Submit".)
<!doctype html>

        <title>CSS form submission</title>

            <form action="" method="post">

You typed:

            <input type="text" />

                <input type="submit">

            </form>

How it works
You might be able to understand it from the commented CSS code above, but, in case you want a full explanation, read on.
First, the form's submit button has an invisible link above it that we style with CSS:

    <input type="submit">

a#submit{ position:absolute; top:0; left:0; height:100%; width:70px; }
When the user clicks the "Submit" button, they're actually clicking the invisible link above it; the user never hits the Submit button and the form itself is never submitted.
What happens instead is that, when the link over the submit button is clicked, the url changes from site.com/form.html to site.com/form.html#page. It's not well known, but you can use the #page part of the URL as a CSS selector with the :target pseudoclass (documentation here). This lets us style the page differently when there is a #page element in the browser's address bar.
And so, when the link is clicked and the user is redirected to #page, we show the 'You typed:' text, hide the submit button, and change the input box styling to show them what they typed. All of this is done using the :target selector.
The CSS rule that looks like #page:target p{display:inline} says "when the #page is the target, display the paragraph text in a line." This allows the input box to be on the same line as the paragraph, instead of beneath it.
Next, the line that looks like #page:target input[type="submit"]{display:none} hides the submit button when the page is the target.
Finally, the line that looks like #page:target input{display:inline-block;border:0px} displays the input box next to the paragraph text, and gets rid of the border. We're actually showing the user the exact same input box they've just typed in! We're just styling it differently.
This could be extended with multiple inputs if required, but I've used one to keep it simple.
Note that browser support for the CSS :target selector is pretty good, but that IE8 and a few other browsers will struggle with it. (Full list here.)
Comment: Wow! Some brilliant people here! Thanks very much for the tips and will experiment with these.
Answer:
Put id="myform" on the  element
Add id="mysubmitbutton" to the submit button on the form
Make sure you include jQuery to your page
add this piece of code somewhere in your page

After these steps you should see the form's output in your browser's console. You can then take the output from $('#myform').serializeArray() and render it in an HTML container using just javascript code, without going through PHP.


Chern Weil theory-user friendly guide

Question: I would like to learn basics about Chern Weil theory but I don't know from which place I should start. I'm after rather basic differential geometry course and have some background in algebraic topology (ordinary homology and cohomology, characteristic classes: Chern, Pontraigin, Stiefel Whitney) but I would like to see geometrical interpretation of the theory of characteristic classes. I will be grateful for any sugestions
Answer: Connection, curvature and cohomology, Vol 1 and Vol 2 Academic Press 1972 by Greub Halperin Vanstone is a very good reference.

Chern Weil theory-user friendly guide


Do I have the right to ask Github to hide my Contribution activity according to General Data Protection Regulation (GDPR)

Question: Do I have the right to ask Github to hide my "Contribution activity" on my public profile page?
Comment: You absolutely have the right to ask, you could ask them to contribute $1 million to your Star Wars figurine collection, whether or not they have to comply with it is a different question (and what I think you are actually asking)...
Comment: @RonBeyer There is no need to be sarcastic (regarding the $1 million contribution for a figurine collection) when somebody seeks orientation about legal matters. That type of sarcasms occurs over and over again in law online forums, which is neither funny nor useful. We all know that an OP always means to inquire whether his position is sufficiently supported on a legal (or equitable) basis.
Comment: @RonBeyer I wouldn't bother moderators for this. I just think we need not be sarcastic about the OP's phrasing of his inquiry, especially where it is clear what he's trying to ascertain. Not sure whether you are the one posting similar sarcasms [here](https://forum.freeadvice.com/threads/can-we-sue.460432/#post-2214282) and [here](https://forum.freeadvice.com/threads/issues-with-neighbors-and-landlord.639175/#post-3511429) under userid *FlyingRon* (maybe it's just a coincidence apropos of the pilot license stated in your profile), but one can make a point effectively without doing that to OPs.
Comment: @IñakiViggers If you feel I'm breaking site rules you may flag my comment for moderator intervention (use the flag below the "up" vote). I did not mean to offend the OP or you, at least a few people found it humorous/useful. The use of exaggeration/obsurdity is an effective technique at conveying an idea. This is not the place to have this discussion, if you want to continue it further, please start a discussion on [Law.Meta](https://law.meta.stackexchange.com/).
Comment: @IñakiViggers That is not me, I'm from Wisconsin, not North Carolina. I'm not a member of any other "law" community online.
Comment: @RonBeyer Got it. Then it was just a coincidence. But now you see my point of how frequently OPs have to deal with that type of comments/posts as they seek an actual answer.
Comment: @IñakiViggers If you want to open a discusson on [Law.Meta](https://law.meta.stackexchange.com/) about this type of comment I suggest you do so. SE is not a forum and we are getting off-topic here. I see your point but I don't believe I did anything wrong, if you want to get/voice an opinion on that, please take it to meta, not here.
Answer: The "Contribution activity" is extracted from repositories hosted on Github. Looking at the privacy statement, Github considers itself as a hosting service for those repositories. See EU Directive 2000/31/EC Article 14 for the exact definition and conditions:

Article 14
Hosting

Where an information society service is provided that consists of the storage of information provided by a recipient of the service,
  Member States shall ensure that the service provider is not liable for
  the information stored at the request of a recipient of the service,
  on condition that:
(a) the provider does not have actual knowledge of illegal activity or
  information and, as regards claims for damages, is not aware of facts
  or circumstances from which the illegal activity or information is
  apparent; or
(b) the provider, upon obtaining such knowledge or awareness, acts
  expeditiously to remove or to disable access to the information.
Paragraph 1 shall not apply when the recipient of the service is acting under the authority or the control of the provider.
This Article shall not affect the possibility for a court or administrative authority, in accordance with Member States' legal
  systems, of requiring the service provider to terminate or prevent an
  infringement, nor does it affect the possibility for Member States of
  establishing procedures governing the removal or disabling of access
  to information.

Article 2(4) GDPR defines that the GDPR does not apply (to Github) in this case

This Regulation shall be without prejudice to the application of Directive 2000/31/EC, in particular of the liability rules of intermediary service providers in Articles 12 to 15 of that Directive.

Extracting data from the repositories to create a nicely formatted contribution activity list, would still be considered hosting as defined at Directive 2000/31/EC, because Github does not (manually) redact or modify commits.
So if you want to hide your contribution activity, you must delete the contributions. And you should not ask Github to do that, but ask the owners of the repositories. And they might have good reasons to deny your request.
If an owner of a repository denies your request without a good reason, you can ask Github to do so. But Github would then probably deny that request, because they explain in their privacy statement that modifying the history is not possible:

The email address you have supplied via your Git commit settings will always be associated with your commits in the Git system. If you chose to make your email address private, you should also update your Git commit settings. We are unable to change or delete data in the Git commit history — the Git software is designed to maintain a record — but we do enable you to control what information you put in that record.

edit
To further clarify why Article 14 of Directive 2000/31/EC applies, see case C-236/08 (Google v. Louis Vuitton) where the European Court of Justice clarifies the meaning of that article (ECLI:EU:C:2010:159):

In that regard, it follows from recital 42 in the preamble to Directive 2000/31 that the exemptions from liability established in that directive cover only cases in which the activity of the information society service provider is 'of a mere technical, automatic and passive nature', which implies that that service provider 'has neither knowledge of nor control over the information which is transmitted or stored'.
Accordingly, in order to establish whether the liability of a referencing service provider may be limited under Article 14 of Directive 2000/31, it is necessary to examine whether the role played by that service provider is neutral, in the sense that its conduct is merely technical, automatic and passive, pointing to a lack of knowledge or control of the data which it stores.

The way Github creates/shows the contribution activity is in my opinion technical, automatic and passive. That means it is not liable, and that implies that the GDPR does not directly apply, unless data is unlawful, and someone notifies Github of that:

The restriction on liability set out in Article 14(1) of Directive 2000/31 applies to cases '[w]here an information society service is provided that consists of the storage of information provided by a recipient of the service' and means that the provider of such a service cannot be held liable for the data which it has stored at the request of a recipient of that service unless that service provider, after having become aware, because of information supplied by an injured party or otherwise, of the unlawful nature of those data or of activities of that recipient, fails to act expeditiously to remove or to disable access to those data.

Surely the GDPR might be the reason data is unlawful. But you need a reason, in particular based on Article 17 ("right to be forgotten"). For example if personal data of a 12 year old child is processed without permission of it's parent. Without such a reason the legitimate interest of the repository owner will probably prevail (who wants to keep the git history complete).
Comment: Interesting take and, I think, a pragmatic answer - but how do you get that "Extracting data from the repositories to create a nicely formatted contribution activity list, would still be considered hosting as defined at Directive 2000/31/EC, because Github does not (manually) redact or modify commits." is considered hosting - as Article 14(1) talks only of storing of information provided by a recipient - the processing of Git commits would appear to be manipulation of data - and thus being used for statistical purposes.
Comment: @davidgo I think Article 21(6) does not directly apply to Github, because the processing is automatic. See my update above. But github must delete unlawful data. But if data is processed based on [Article 89(1)](https://gdpr-info.eu/art-89-gdpr/), (like statical purposes) then [Article 17(3)(d)](https://gdpr-info.eu/art-17-gdpr/) denies the right to erasure if it seriously impairs the achievement of the objectives of that processing. Removing data from the git history requires a rebase, invalidates all hashes, and causes lots of problems. So I don't think that will work.
Answer: Assuming that the GDPR applies (which would seem to be the case - regardless of where you are in the world based on the Github Privacy statement), then its arguable that you should be granted this if you have a valid reason in accordance with Article 21(6) of the GDPR which reads

"Where personal data are processed for scientific or historical
  research purposes or statistical purposes pursuant to Article 89(1),
  the data subject, on grounds relating to his or her particular
  situation, shall have the right to object to processing of personal
  data concerning him or her, unless the processing is necessary for the
  performance of a task carried out for reasons of public interest."

(By my reading section 89 allows them to process this data after anonymising it)
Its also relevant to quote Githubs page on how to control your data which includes the data they collect about you -

"If you're already a GitHub user, you may access, update, alter, or
  delete your basic user profile information by editing your user
  profile or contacting GitHub Support. You can control the information
  we collect about you by limiting what information is in your profile,
  by updating out of date information, or by contacting GitHub Support."


Galaxy Note 10.1, does not recognize finger touch

Question: I have a Galaxy Note 10.1, It suddenly stopped (when switched on) finger touch detection, but works with normally with S Pen. I tried Factory resetting but still it does not detect finger touch... I tried to find any setting regarding finger touch but I couldn't. Is there a way to fix this?
Comment: How long have you had your Note for before it started doing this?
Comment: @Denny After about a week... :(, After another two weeks time it worked normally.. :)
Comment: If you have the Samsung Book Cover, try closing it (which turns off the screen) and opening it. The screen should turn on again and finger touch will work again. You can also do this by holding a magnet to the sides of the screen (the book cover has little magnets in it). This solved the problem for me instantly, where previously only the S-Pen worked but not my fingers. For some reason I cannot add this as an answer even though I have more than 100 rep.
Answer: Go to settings, then language and input, then Samsung keyboard settings, then handwriting, then recognition time. Try changing it and then try touching. Sometimes this could solve. Also try touching the 4 corners.
Comment: I tried changing `Recognition Time` but no avail. :( , What do you mean by touching 4 corners? Anyway thanks for the answer...
Comment: Since Note 10.1 is auto calibrated,touching the four corners of the screen will do some help. :-)
Answer: This video describes an issue that could be related to your problem.
Answer: Let it run dead to the point where it won't turn on, charge it till full (without using it at all) turn it back on and it should. Be fine. Happened to me. :)


Set unpublish status for a Component

Question: Is there an API call in 2009 SP1 to set a component to unpublished similar to objPage.SetPublishedTo?
Comment: Nuno addresses this here: http://tridion.stackexchange.com/questions/2302/setpublishedto-with-coreservice
Answer: This is where, again, Tridion is technically correct... but it takes some mind-twisting to find it.
Components are not published - component presentations are. To set a component presentation as unpublished, use the ComponentTemplate's class "SetPublishedTo" method. I can't recall the details anymore, pretty sure you need to pass something like component URI + Publication Target and you're all set.

Set unpublish status for a Component


Some bones won't move in pose mode

Question: Some bones wont move when I'm in pose mode. For example the head, the neck and the upper spike move without a problem. But when I try to move the eyes and the other spikes only the bones move not the mech. I've parented them all to the head. And did the weight painting myself. Does anyone know what may be wrong?
Comment: I checked your file. There are no influences on the eye bones, but I can paint them in weight paint. And if I save the file and reload, it still works fine. So may be you missed something. Try to repaint the wiegths for the eye bones.
Answer: You have the vertex groups for your weights but they are not assigned to the bones, simply rename the vertex group to the same name as the bone they are suppose to be assigned to and that should fix it.
Comment: Thank you a lot!
Comment: No problem, for future reference with characters I would recommend using the Automatic weighting after selecting the mesh then armature hit Ctrl + P and select "With Automatic Weights" from the menu. This will create vertex groups automatically based on bone names then you just have to go in and make tweaks to your weights in weight paint mode.

Some bones won't move in pose mode


How do bots communicate in the zeus botnet?

Question: I read on http://www.abuse.ch/?p=3499 that: ZeuS is now using an "IP list" which contains the IP addresses of other drones participating in the P2P botnet. An initial list of IP addresses is hardcoded in the ZeuS binary.
From what I understand, the bots use a hardcoded ip list to communicate with each other. what I don't understand is, how can bots behind a NAT network communicate with each other when the IP addresses behind a NAT network are invalid?
Answer: You could read something like Infosec Institute's Botnets Unearthed – The ZEUS BOT, but it boils down to:
It's not a peer to peer setup, it's a client/server setup.  Malware clients try to contact command and control servers which are not behind firewalls that prevent access.
You see a list of command and control nodes (or, better, make sure your own firewall is blocking all of them) at the ZeuS Tracker, which is the source of the I-Blocklist ZeuS blocklist (and many others).
Answer: There are a couple of ways. First, there are plenty of computers that are not behind NATing firewalls - the owners might be relying on Windows Firewall, or on nothing at all.  Someone with a cable modem and PC with no router is wide open.
Or a stateful firewall could be returning UDP packets to the originating machine.
Answer: Connecting in spite of NATs is called NAT Traversal. From the Wikipedia page:

Many techniques exist, but no single method works in every situation since NAT behavior is not standardized. Many NAT traversal techniques require assistance from a server at a publicly routable IP address.

Hence, the hardcoded IPs.
NAT Traversal is a minefield and not something I'm qualified to explain. However, the Wikipedia page does contain a handy list of techniques. Of particular interest is Hole Punching which, if successful, does not require a server at all.