Distribution of residual term in regression.

Question: In regression analysis for classical linear regression model the residual term is independent of x and y and normally distributed and it is a random variable but i found somewhere written u~N and u~NID.I cannot understand the difference so can someone explain the meaning of NID (normally and independently distributed)?(sorry for my bad English).
Answer: In linear regression with Gaussian (and heteroscedastic) noise, our model assumes that for $n$ observations of data, for each $i \in [n]$,
$$Y_i = \beta X_i + \epsilon_i,$$
where $\epsilon_i$ is our ERROR term for the $i$th observation (note that residual $e_i$ is an estimator of $\epsilon_i$) Such that $\epsilon_i \sim N(0,\sigma^2_i).$ NID means "Gaussian and independently distributed", which is essentially a slightly more lenient way of saying that $\forall i \in [n],$ $\epsilon_i$ is independent of $\epsilon_j$, $j \neq i$ (i.e. errors are independent across observations).
Note that our residual $e_i$ is not necessarily independent of $Y_i$ depending on how we estimate $\epsilon_i$. Most of the time, our residuals are modeled as $e_i = \hat{Y}_i - Y_i,$ where $\hat{Y}_i$ is our prediction for the $i$th observation generated as
$$\hat{Y}_i = \hat{\beta}X_i.$$
In this case, $e_i$ is not independent of $Y_i$.
Comment: (I will just leave my comment here to add up to what is said. Sorry, I didn't expect you to edit your answer). Looks like a lot of papers use "normally and independently distributed" (sometimes adding - "with constant variance") in a sense on normal and i.i.d. However, I [found clear evidence](http://www.lse.ac.uk/statistics/documents/researchreport99.pdf#page=3) that it can be used to the model, where variance is not constant, so it is better to keep that in mind.
Comment: I think your residual expression might be $e_i=Y_i-\hat{Y}_i$
Answer: "In regression analysis for classical linear regression model the residual term is independent of x and y." The error term must be assumed to be independent of x if the regression is to be unbiased, but it cannot be independent of y since it is a stochastic driver of y (y = a + b*x + error). The assumption that the error term is normally distributed is in general NOT required, unless the sample is small and the researcher wishes to rely upon "exact" t-statistics.
Beware, the answer shown above is semi-informed gibberish, from someone who doesn't know what "heteroscedastic" means, nor how a regression residual is defined.


Books for function fields and algebraic curves

Question: I'm just finished my learning of algebraic number theory, and I want to go for some algebraic geometry which I basically know nothing about. At the same time, I'm informed that there're lots of analogues between number fields and function fields which relates closely to algebraic curves (I guess). So, is there any books that study function fields in certain depth (so we can get some analogues of cohomology groups, Adeles, Ideles, Riemann-Roch, etc) and include basic algebraic geometry? Thanks for advising.
Comment: "Algebraic Function Fields and Codes" by Henning Stichtenoth.
Answer: Plane algebraic curves by Fischer


Make Portage install non-free software after confirmation

Question: So, in my make.conf I have ACCEPT_LICENSE="@FREE" variable set up, but I still want to use some proprietary software. Best case scenario would be Portage warning that the software I'm going to install is not free and then ask for a confirmation to proceed. Is that possible?
Comment: BTW. I'm not sure if it shouldn't be `ACCEPT_LICENSE="-* @FREE"` - don't allow anything, allow free.
Comment: https://wiki.gentoo.org/wiki//etc/portage/make.conf#ACCEPT_LICENSE
Answer: I have ACCEPT_LICENSES="-* @FREE", yet sadly need some proprietary software for school once in while. I solved this using the optional file in /etc/portage, package.license, where you can instruct portage to make exceptions for certain licenses on certain packages.
The format of package.license is similar to package.use: you supply one package per line, in the format of category/package license. You can use # to start comments as well.
You can also make /etc/portage/package.license a directory, like the other configuration files in there. In that case, it will read all files inside this directory.
Using this configuration, when you try to install software with licenses not included in @FREE, portage will complain about it. It will inform you which packages require which licenses to be accepted, which you can then add to your package.license configuration.
Answer:
Add ACCEPT_LICENSE="-* @FREE" in the /etc/portage/make.conf
Add ACCEPT_LICENSE="*" in the /etc/portage/env/accept_license.conf

Then you can allow specific packages you want creating a file on /etc/portage/package.env.
E.g (/etc/portage/package.env/non-free):
<category>/<some-software> accept_license.conf

Comment: One may use `/etc/portage/package.license` directly, but you have to specify the exact allowed licenses.


Grub2 doesn't show Windows 7

Question: I did reinstall UBUNTU 14.04 after having some issues with grub, the problem is that I can't access to my windows 7 anymore as the grub menu shows only Ubuntu partition.
P.S/
during the reinstallation of ubuntu, I did choose 'erase and reinstall ubuntu .... ' instead of install 'ubuntu alongside ubuntu...'
Windows was always in dual boot with Ubuntu but now I can't access to it.
So please help me
Answer: Have you checked, if the Windows partitions are still available. For instance in you file-manager (nautilus) or a partition tool like "disks" (not sure about the name, as I run a German version) or gparted.
If the Windows-partition are gone - sorry, but you lost Win.
If the Windows-partition(s) is/are still on the disk, open a terminal and run sudo update-grub. Copy the resulting output to an editor (gedit) and save it.
Then try a reboot and see if the grub-menu has changed. If not, paste the output from above here.
Comment: When I checked via sudo update-grub2 it didn't show up any Windows 7 (loader) partion like only the Ubuntu partition. I think that Windows was erased too! Now I am trying other stuff. I will do your guides as soon as I finish. thanks
Comment: azed@Kalypso:~$ sudo update-grub2
[sudo] password for azed:
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.13.0-32-generic
Found initrd image: /boot/initrd.img-3.13.0-32-generic
done
Comment: Sorry - Win is gone. :-( As I am not the data-recover-wizzard I can only suggest, to install gparted and try the data-rescue option in the "partition-menu". (You will then be asked to install a package, of which I can't remember the name. But all needed packages are available in the repositories.)
Comment: Yah, it is gone, tough day, I can't understand how it did happen, I have my stuff on cloud, so not that horrible, but it's sad, Viele Danke Blumchen Blau,

Grub2 doesn't show Windows 7


Not Getting standard boot countdown screen in Dualboot (Linux 6.2 & Windows 8)

Question: Problem I have installed (Dual Booted) Red Hat 6.2 on a Windows machine ,In windows boot manager it is not showing Linux ,its only showing windows 8 . I am pressing arrow keys but only windows 8 is coming. Any solution to it help me out?
Answer: Since this is the place for Linux/Unix, I suggest your thrash away the windows bootloader, and install grub from Linux distribution. BTW, RHEL 6.2 is way too old. Switch to newer ones unless you are limited by a license. Latest is 6.5, though Their 7 beta is out. To install grub and update,
<code>sudo grub-install /dev/sda
sudo grub-mkconfig -o /boot/grub/grub.cfg
</code>
It might be grub2-mkconfig if your grub version is 2.


What iOS developers need from a UI/UX designer?

Question: So I am fairly new to UI/UX design (pretty much learning on the go).  I am building a native iOS app and need to deliver the designs to the developer.  I have built an interactive prototype using Proto.io, but my question is basically where do I design the app and what exactly do I have to give to the developer to code it?  I know how to use Photoshop and Illustrator.  My gut tells me that I can just design the screens in Illustrator and send the developer an organized library of all of the elements on the screen as png files?  And the other question is how do I build the interation part of it in?
Comment: This is a question only your developer(s) can answer.
Comment: Welcome to the site, @Kj_Singh!  You have a lot of questions here and answering them all could fill several books.  Please pick one question per post and describe concretely what you have done to solve it and what you still need to know.
Comment: @DA01 very bad idea. This will only create confusion and deteriorate your leadership.
Comment: @Knu UX does not 'lead' development. UX should be working 'along side' of development. That doesn't mean you give into to all of dev's demands, but rather, that you maintain open communication and agree on what the deliverables should be.
Comment: I would say a better way to view it is that UX feeds development. In agile terms UX provides stories and supplements (and informs) the backlog. If working correctly developers will have input into the UX process, just as visual design does.
Answer: In my experience of working with iOS developers, this is normally been my deliverables to them.

An interactive prototype which shows the different interactions between the screens and the interactions in the screens itself
Visual assets of all the elements in the screen (e.g Backgrounds,buttons,icons,indicators etc) - Do note if you are designing for Iphone 3s and Above, you will need to provide two sets of assets i.e. one with the retina sizes and one without retina sizes (so x and 2x sizes)
I specify details such as fonts used and the sizing of the fonts

I also recommend looking at this excellent article which talks about how to design for iOS apps. To quote the article about how to deliver content

Organize. Each screen should have it's own folder with the screen's name. Each folder should have a screenshot of the whole
  screen so I will understand how the final result should look like. The
  rest of the files in this folder are the elements cut into pieces:
  buttons, cells, borders, whatever, each separately in its own file.
Be consistent. All graphic files must be PNGs.
Understand iOS graphics. Each graphic file must have two versions: an high-res version and a low-res version. The first version
  will be used for iPhones with retina display (iPhone 4 and later) and
  the second version for non-retina display devices (older iPhones and
  iPads).
Name Clearly. The low-res version should have a good descriptive name such as BigBlueButtonNormalState.PNG and the high-res
  version should have the same name with a @2x suffix:
  firstname.lastname@example.com - The @2x suffix is read by the iPhone
  and used if retina display is available.
Size correctly. The high-res version must be double the size of the low-res version. If the low-res version is 100x150 pixels then the
  high-res must be 200x300 pixels. Now I know you create the high-res
  version first and then downscale it, so just make sure your high-res
  version is even (width has even number of pixels and so does the
  height).
Comment: If your app is using standard iOS interface elements do you still expect all the assets as PNGs and different resolutions? More generally: how is the process different if using standard iOS interface elements?


Notebook wakes up after disconnecting mouse

Question: My Win7 notebook wakes up from sleep after disconnecting mouse. It is very annoying since I usually disconnect the mouse when I want to put it in the bag and leave. Vista behaves in the same manner. How can I change this behaviour?
Answer: Control Panel->  (window/startmenu -> control panel)
Mouse-> (icon)
Hardware-> (tab)
Properties-> (button)
Change Setting-> (button:vista/win 7 only)
PowerManagement-> (tab)
Allow this device to bring the computer out of standby (checkbox)
Comment: It doesn't fix the problem entirely, because the mouse can't wake the computer at all (not just on unplugging)... but since it's a laptop mouse, I suspect it's a minor inconvenience.


Multi-collinearity

Question: I have a binary response variable (presence/absence) and four independent variables (min.temp, max.temp, precipitation and elevation. My scatter matrix is showing collinearity between 3 of the variables with cor.efficients of 0.73, 0.74, 0.84. ELevation however doesn't seem correlated with the rest. I therefore thought it was best to run binary logistic regression on each variable seperately with elevation? However, when I checked the vif Score of the model when all were included it was only showing min.temp as high (9.13) and max temp (4.7) so it appeared I could include all but min.temp....I'm confused.
Comment: Better title could be framed, I guess, to articulate your query.
Comment: I'm not convinced that you need to do anything at all to address multicollinearity, and I'm definitely not convinced that the potential bias introduced by dropping a variable is worth the reduced variance in estimating what remains.
Comment: Welcome to Cross Validated! Why not include all of the variables?
Comment: It sure seems like you have collinearity. Why do you see that to be a problem? I discuss [here](https://stats.stackexchange.com/a/563175/247274) some of the misunderstandings surrounding this topic.
Comment: 93 sample points, 78 present, 15 absent
Comment: yes, you're right, a better title is needed. I thought there is no point running a regression with all variables if there is collinearity between most of them? I am new to statistics and confused whether I should be going off the correlation coefficient or the Vif score?
Comment: ok thanks, so you're saying they are correlation coefficients are not large enough to be classed as collinearity?
Comment: How many data do you have?  What is the percentage present / absent?
Answer: There's a lot of information on the site about multicollinearity, it may benefit you to click on the multicollinearity tag, sort by votes or frequently cited, and start reading to learn about the topic.
In general, multicollinearity means that some of your variables 'point' in the same direction / aren't distinct from each other.  As a result, it's hard for the model to know which is associated with the response.  That doesn't necessarily impair the estimates of the coefficients, but it makes the estimates much less certain.  That is, the standard errors, CIs, etc., will be much wider.  It means you'll have less power than you otherwise would have, although you still might get significant results (see my answer to: What is the effect of having correlated predictors in a multiple regression model?).
Regarding how to detect collinearity, the VIF is superior to looking at marginal correlations.  By convention, collinearity is problematic if the VIF is greater than 10.  Your largest VIF is lower than that, so by this convention, it isn't a problem.  If there were a problem, it would only mean that you might get a non-significant result even though there was a real association.  A way to deal with that would be to drop all three strongly related variables and perform a nested model test.  The multicollinearity wouldn't affect that test.  If it were significant, then you might be confident that at least one of those variables was related, but without more information, it would be difficult to know which.
None of that is really your problem, though.  The biggest issue here is that there is very little information in binary data (i.e., presence/absence).  A basic rule of thumb is that you need at least 15 of the less commonly occurring category (here, absent) for each variable you want to include.  You might have enough information for a single variable, but not four.  As an exploratory analysis, you could run four different univariate logistic regressions, but it's sort of cheating.  It might provide some information about where to look further, but you wouldn't want to draw any firm conclusions.
Comment: Thankyou, that's all very helpful.  I didn't choose the dataset unfortunately. When I have run the four univariate regressions elevation has come up as the most statistically significant.  Sorry for being dumb, so you are basically saying I should be ok to run it as a whole? All four variables included also shows as statistically significant ..
Comment: It's a rule of thumb.  I'd be quite wary of running a model with 4 variables where you only have 15 absents, but there's no law against it.  The police aren't going to show up at your door.  Good luck.
Comment: Thankyou so much.

Multi-collinearity


Has anyone suffer a recent failure on Instances located on us-east-1b for AWS?

Question: I have servers located on us-east-1b and us-east-1c.  All my servers on 1b are inaccessible.  Is anyone else having this issue on the Amazon Cloud?
Answer: I don't see it happening now but it's happenend to me in the past.  It seems to me pretty typical behavior.
Answer: And keep in mind that what for you is availability zone us-east-1a might be 1b or 1d for another EC2 account.
The availability zone names aren't identical for everyone, Amazon arranges them in a different way for every EC2 account.


Is the hand a player receives completely determined by the way the deck is shuffled?

Question: I am wondering whether the hand which a player receives is completely determined by the way in which the deck is shuffled- that the permutation of the cards after they are shuffled completely determines the hand a certain player, and that the cards the player is dealt with aren't randomly chosen when the dealer draws from the shuffled stack of cards. I am asking so that I can answer probability questions about poker.
Answer: Combinatorically, it doesn't matter whether the shuffle occurs before any card is dealt or if the cards are constantly being shuffled, provided there's no observation made by anyone in advance of selecting each card (i.e., we can't force a reshuffle because we don't like the card we'd otherwise select).  So imagine an online game where the deck is shuffled and cards are successively drawn without reshuffle.  This results in completely the same mathematics as reshuffling the remaining cards after each card is dealt (without replacement, of course).
Personally I adopt the theory of "quantum mechanics of poker" and that the next card isn't determined until it is observed by someone.  Of course a particular card could be ruled out if observed by someone else in the hand. But the wave function of a particular card doesn't collapse until observed.
Adopt this mentality and you're less likely to tilt because of external factors, such as seeing you would have hit your out after you fold.  (Because had you called, the river card might have been different!)
Answer: I'm not 100% clear on your question, I can interpret it two ways, and I'll answer both ways.
Yes, assuming we're talking a clean casino shuffle, the deck will be sufficiently randomised but once the cards are shuffled, assuming also a fair deal (i.e. no card mechanics) and no mistakes the players will received the cards based on the order of the shuffle no change.
If you're talking about if we are doing special types of shuffles to ensure, as an example, that seat 1 always gets aces, yes this is possible. It's called card mechanics. Some people are very very good at this. They can shuffle the deck and end up with the exact order they want.
If we assume a person is not a card mechanic, regardless of how they shuffle the cards, as long as they have done a reasonable job of mixing the cards it should be random, and not able to predetermine cards.
Answer: There are draw poker games where the cards available to a player depend on how earlier players in the hand have drawn.   This isn't the case for hold'em.
If you have a game where people might join or leave, then the number of players in a hand might be determined after the shuffle is completed.   That would change the specific cards to players.
For a given number of players and a non-drawing game like holdem, the hole and community cards should be completely determined.   But it is possible for dealing irregularities to occur that do not result in a misdeal, but modify which cards are used.
For probability questions, I'm assuming none of these affect what you were considering.   But they can occur in real play.
Answer: It mostly depends on the game you might be playing, some games like stud and draw poker, rather a player drops out or stays in the hand can effect the cards A player receives, with omaha and hold-em games rather or not a player stays in the hand has no effect on the cards that will be dealt, nothing really effects the order of the cards, accept perhaps an optional cutting of the deck that is allowed in some games typically before the flop where the players deal the cards.


same RMS error for different resolution data

Question: if i rectify a low resolution data and high resolution data and both have same RMS error =1 then what would be rectify more accurately? means for which resolution this error is more acceptable comparatively to other ?
Answer: The relationship is an inverse one. For example, if you have a 1 m error in a 30 m pixel, the percentage of error is much smaller than if you have a 1 m error in a 15 m pixel.
Comment: yes in case of meters but we calculate errors in pixel size on raw data then i think high resolution data is better rectified   make me correct if i am wrong
Comment: I'm sorry, not really clear on what you're asking here. Are you concerned with which image you should rectify or which image will rectify most accurately? If the latter, my original answer still holds.
Comment: i am  concerned with unrectified image means the image on which i want to apply rectification. and i am considering value of RMSE in Pixel unit of unrectified image.


How do you download packages for TeXworks on Windows 7?

Question: I am using TeXworks on Windows 7 and I want to use the algorithmic package. However, when I try to include it it just says I need to download that package, but I can't figure out how to download it (TeXworks asks if you want to download it automatically, but that doesn't seem to work, because nothing visible happens)
Answer: If you use MiKTeX, open the MiKTeX Package Manager aka mpm and choose to install the algorithms package. It contains the algorithmic package.
If you use TeX Live, do the same with the TeX Live Manager aka tlmgr.
Each of these programs should be available in the Windows start menu if the corresponding TeX distribution has been installed.
Comment: I might need your help. I'm downloading Lilypond because I read that I can use it to include musical examples in TeX documents.


Is there any relation between "genius" and "ingenious"?

Question: They seem to mean the same thing, yet when spoken they sound like the negative of each other.
What's the secret behind those two words?
Comment: The second word derives from "ingenuity", which geniuses sometimes have.
Answer: On the surface, one might think that ingenious is somehow based on the word genius.  Interestingly, this is not true.
The word ingenious does not actually have the in- prefix for negation.  Instead, it comes originally from the Latin ingeniōsus, which means "intellectual, talented, ingenious".  At times in history it was also spelled "engenious".  Indeed, ingeniōsus appears to be the same root that gave us the word engine.
Genius was originally different, but evolved to have a meaning that is similar to ingenious.  It came to us from Latin, but it was originally Greek.  According to the OED, it mainly had the meaning of, approximately, "genie" or similar type of spirit, in Latin.  Figuratively, it was also used to mean "characteristic disposition; inclination; bent, turn or temper of mind."  In English, German, and most of the Romance languages aside from Latin, it had the meaning of "natural ability" starting around the 1600s.  The OED speculates that the meaning of genie was pushed towards the meaning of ingenious because of "confusion" between the two (that is, their superficial similarity).
Comment: @Cerberus: OED says: "< Latin genius, < *gen- root of gi-gn-ĕre to beget, Greek γίγνεσθαι to be born, come into being."  So that is where I got that idea. Am I misunderstanding the OED etymology shorthand?
Comment: Oh, I see. I think they'd put `f.` ("from") or `<` before *Greek* if they meant that it came from Greek. In your quote, they trace back the etymology to **gen-*, then proceed to say that **gen-* is also the root of gignere, [and of] Greek gignesthai. It is kind of stupid that they still use these awkward run-on etymologies in the digital age, and with impossible abbreviations. I am forced to look up `a.` every time I use the dictionary, because I just cannot remember that it means *adopted from* (I looked it up again just now).
Comment: I had thought there was a separate notation to indicate sibling words, but I think you are right.  Maybe it isn't used consistently.  As for the formatting, I guess the current OED overhaul (completion date: 2037!) began back in the early 90s when book space was still a reasonable concern, and so they are probably keeping the format consistent throughout this version.  It is depressing to think that, at this pace, they will never have a digitally-savvy version of the OED during our lifetimes!  This is not the first time I have been confused by the super-compact way things are worded in there.
Comment: Excellent explanation. Just one thing: where did you find that *genius* came from Greek? The major Latin dictionaries (OLD, L&S) simply say it comes from the Latin/PIE root *gen-*, like *ingenium/-osus*, and LSJ says no similar word exists in Greek. The OED doesn't say anything about a Greek origin either.
Comment: Oh dear, that is sad indeed! Well, at least our children will get to live in a better world than we.
Answer: Though in view of the answer above, I thought to quote two answers from this Reddit question which retrograde to Proto-Indo-European. I edit them lightly to improve readability.

By: user 'gnorrn', 2015 July 26
The duality goes all the way back to Latin:

genius meant "the tutelar deity of a person or place"
ingenium meant "innate or natural quality, nature"

Both words ultimately derive from the Proto-Indo-European root *ǵenh₁-
("to produce, to beget, to give birth"). The prefix in- has several meanings in Latin. Here it does not have the privative/negation meaning (cognate with English "un-"), but the meaning of "in, into".

By: user 'wurrukatte', 2015 July 26
[Originally, the querier exemplified with 1. in cantation and in carceration and 2. in genius .]
In 1 and 2, in- is not the same prefix. It is the same morpheme for two different prefixes that happened to become homophonous.
In 1, in- means "not". This in- goes back to PIE '*n̥-', which gave Germanic languages like English the prefix 'un-'.
In 2, the other prefix in- is actually a preverb going back to PIE *h₁en, "in, into", which gave Germanic *in > English 'in', "in, within".
In Latin, both PIE forms resulted in the form 'in(-)'. In other languages, they didn't necessarily become homophones, just as in English, like Ancient Greek 'a(n)-' and 'en-'.
English also has two homophonous prefixes that mean different things: 'un-' meaning 'not', as said, goes back to PIE '*n̥-'.
In contrast, 'un-' can also mean "reversal , opposite" as used with verbs like 'undo', 'unlike'. This goes back to Old English 'an(d)-', from Proto-Germanic *and-, from PIE *h₂enti-.
This 'un-' is cognate with Ancient Greek 'anti-' and Latin 'ante'.


Flash Player Plugin on Firefox will not update on Ubuntu 11.10 32 bit

Question: I am running on Ubuntu 11.10 32 bit, and my flash player plug-in for Firefox is outdated. I must update my plug-in to flash player 11, but I am not able. I have already installed Adobe Flash Player via Ubuntu Software center (As it prompted me to after trying to download from the Adobe site) Without the plug-in updated, videos can not be played from directly on a Facebook page, and I believe that it distorts the video player on Youtube. (Image of player can be seen at imgur.com/gYbFx)
Comment: @EliahKagan No upvoted answers, and the one that likely will help [is invalid right now](http://askubuntu.com/a/124101/169736)
Comment: My suggestion: **Do not reopen this question:** It's no longer relevant and all the answers are hopelessly outdated.
Answer: Try this.
<code>sudo apt-get purge flashplugin-installer
sudo apt-get install adobe-flashplugin
</code>
Then, open up a YouTube video, right-click on the video itself and click on Settings.
Uncheck the "Enable hardware acceleration" checkbox in the Display tab.
Your Flash video should now work.
Comment: Neither command worked, saying that my plug-in was up to date when I know it is not. I was unable to reach the "settings" after right clicking the video on YouTube, the choices consisted of file, edit, view, movie control, and help none of which contained a display tab or check box for "enable hardware acceleration."
Comment: It worked for me
Answer: I did this for Ubuntu 11.10. Download google chrome(not chromium but chrome from google, not the repos), find where the flash file for chrome is located in your directory, it's called "libgcflashplayer.so". Copy it to your desktop and change the name to "libflashplayer.so". Find where Mozilla Firefox keeps the Flash file for Firefox in your directory and replace it with the one you just changed the name of. To replace it I used rootnautilus, drag and drop, just type in gksudo nautilus in terminal.
 It worked for me. I even replaced it with an archived version of adobe flash 9 and it worked, but the version in Chrome is 11.
Answer: Try to install this add-on on firefox :
https://addons.mozilla.org/en-US/firefox/addon/flash-aid/
After installation, click on "quickmode" and "install stable flash". It will open your terminal, remove the old version and install the new one.
This fixed my problem. Good luck!
Comment: This fixed my problem too!
Comment: This add-on has been removed by its author.


AWS Security group

Question: In my aws account I have a VPC with front-end nodes and a mongo EC2-Classic. The front-end nodes are in a Elastic Beanstalk environment with auto scaling so when new instances appear I have to allow access in mongo's security group. I want to avoid having to do that every time when a new instances appears and the only solution I found was to migrate the mongo instance into the VPC. Is there another solution in which I can allow access only for the members from a certain VPC ?
Comment: Have you tried ClassicLink?
Answer: The simplest way to create a Managed NAT within your VPC and make your MangoDB Security Group whitelist the NAT ip. The NAT will have an elastic IP so whatever instances are in the VPC will always have that exit ip.

AWS Security group


Why are certain animals hidden from muggles?

Question: Throughout the 7 books we are introduced to animals that exist only in the wizarding world. Why would the Ministry go to all the trouble of hiding them from muggles when lots of them are similar to animals that muggles are very familiar with? It seems like a waste of time and resources. What makes these animals worth hiding?
Comment: Two reasons that spring to mind: 1) Preserving the secrecy of the magical world. If Muggles never see an animal, they can't study it and learn the existence of magic. 2) Risk of harm. Humans have a history of being quite nasty to the things they encounter. And in the other direction, a Muggle who met a Manticore or Lethifold would probably end messily.
Comment: If ground tiger bones are a supposed miracle cure, just imagine the ground bones of -insert magical beast here-.
Comment: Reason 2 is quite interesting, do you have any cannon references to back it up?
Comment: I don't think Rowling has ever addressed the question of whether Darwin's theory of evolution is true in the Harry Potter universe, but we could speculate that while it is true for "mundane" animals, the creatures that are kept hidden are the ones that were created artifically by people with magical abilities in the distant past--we know this is true of the first Basilisk which was created by [Herpo the Foul](http://harrypotter.wikia.com/wiki/Herpo_the_Foul%27s_basilisk), so it seems at least plausible it's true of the others.
Comment: Possible dupe? http://scifi.stackexchange.com/questions/86650/why-dont-muggles-know-about-magical-mythological-creatures/86653#86653
Comment: @Richard I think they're subtly different. That question is more about mechanics (how are Muggles kept away from magical creatures); this is more why.
Comment: @alexwlchan - I'd agree with that.
Answer: If you want more background on why magical creatures are hidden from Muggle eyes, then I recommend reading the introduction of Fantastic Beasts and Where to Find Them. It contains a "brief" history of Muggle interactions with magical creatures, and why, in 1692, the wizarding community decided to conceal twenty-seven species of creature from Muggle eyes.
A couple of reasons:

It could be dangerous for the magical community.
Dumbledore explains that Muggle sightings of magical creatures made the magical community less safe:

Imperfect understanding is often more dangerous than ignorance, and the Muggles' fear of magic was undoubtedly increased by their dread of what might be lurking in their herb gardens. Muggle persecution of wizards at the time was reaching a pitch hitherto unknown and sightings of such beasts as dragons and Hippogriffs were contributing to Muggle hysteria.

(This follows a Muggle monk's account of a particularly dangerous ferret, which Dumbledore guessed was a Jarvey, a sort of talking ferret.) That's probably not as much of a problem today as it once was, but you can see why it was considered when the ban was first enforced. And the law has probably never been re-examined.
It would risk the secrecy of the magical community.
Today, we largely accept that creatures from historical legend are fictitious. Now imagine we found conclusive proof of dragons, and perhaps even proof that they'd existed for hundreds of years. That would cause us to examine a lot of assumptions about historical legends.
There are enough historical accounts of magic to make the magical community quite nervous. They don't want us re-opening old wounds.
(If you read Fantastic Beasts, it sometimes explains what makes a creature unusual and worth hiding from Muggles. For example, Kneazles are "sufficiently unusual in appearance to attract Muggle interest"; remember that Crookshanks looks like a normal cat because he's only half-Kneazle.)
This goes for small creatures too: enough sightings of weird-looking ginger cats is going to get prying eyes aroused.
It would be dangerous for Muggles and the creatures involved.
Muggles and unusual creatures don't mix. There is a long history of humans hunting creatures to extinction, and even scientific missions of discovery can end with the creatures coming worse off. (For example, the giant tortoises that Darwin discovered on the Galápagos turned out to be so tasty that a lot of them got eaten.) Given Muggle barbarism, can the wizarding community be blamed for wanting to protect a few special creatures from us?
On the flipside, a lot of magical creatures would be dangerous to Muggles, who are ill-informed and ill-equipped to deal with them. (Remember that it's a UK-centric universe, where guns among Muggles would be scarce.) There are lots of dangerous creatures – Lethifolds, Quintapeds, Dragons, Manticores – which would wreak havoc among Muggle communities.
Comment: An excellent answer.
Comment: In fairness to the muggle world, we don't know how many Wizards sailed on the Beagle, and Wizards aren't exactly benign, let alone peaceful. I seem to recall several Wizards who too great pleasure in the torture of muggles. This is why I think the Minister for Magic should be a muggle, to keep a track on these dangerous miscreants.
Answer: It reveals that magic does exist to the non-wizarding world

"everyone would be looking for a magical way. it would be absolute chaos"

and the wizarding world wants to stay hidden, since its better for everyone.
Comment: I'm not asking why creatures like dragons are kept hidden but more why creatures like kneazles are
Comment: well, maybe you should have specified that that is what you meant. either way, its the same answer.
Answer: First off, animals from the wizarding world would not react well to Muggles. A lot of them need special care and a Muggle wouldn't know what to do with it. The animals might be dangerous or exhibit magical powers.
Therefore (secondly), Muggles would be put in danger by being exposed to things like dragons and hippogriffs.
Thirdly, this would break the Statute of Secrecy, with was sanctioned for a good reason. The Wizards had some past experiences with Muggles and would not like to repeat that.
Answer: Remember in Book One when the Owls flood the house with letters for Harry?
The Dursley's reaction to regular animals displaying magical events was over the top frightened. Imagine if they were in front of a hippogriff.
Comment: The Dursley's are a parody of a muggle. Many muggles would react with curiosity to a hippogriff.
Comment: True. Maybe an [Acromantula](http://harrypotter.wikia.com/wiki/Acromantula) and a [Manticore](http://harrypotter.wikia.com/wiki/Manticore) are better examples


Maxwell's equations and wave equations

Question: As can be proven, Maxwell's equations don't work for spherical or cylindrical waves, but these waves satisfy the wave equation. Are there any other examples of this type that satisfy the wave equation but not Maxwell's equations?
Comment: Can you elaborate what you mean by "Maxwell's equations don't work for spherical or cylindrical waves"? Any reference will also do.
Comment: Jackson chapter 8 section 8.2 discusses cylindrical waveguides and cavities, how does that example act as something that doesn't satisfy Maxwell's equations yet satisfy the wave equation? If you read Jackson ch. 6 sec 6.1-6.2 he derives two wave equations from Maxwell's equations in vacuum that are equivalent to Maxwell's equations in vacuum when you impose the Lorentz condition, so I'd be interested to see what you mean? Maybe you mean Maxwell's equations in the presence of source charges, which do not satisfy the wave equation (Landau vol 2 sec 51)?
Comment: Cylindrical waveguides is a good example. Let me have a look at Jackson and Landau. However, this question is headed the other way. Spherical and cylindrical waves do satisfy the differential wave equation, but do not satisfy Maxwell's equations due to the additional constraints of ∇∙E=0, and ∇∙B=0, that are, as you said, the indication of the absence of source charges (If I am not wrong haha).
Answer: Mmm, the wave equation is a consequence of Maxwell's equations plus a gauge condition, and once you cast the wave equation into spherical, or cylindrical coordinates, you can easily find solutions that satisfy it. Maybe you mean waves that are spherically symmetric? In that case, the problem is more about finding non-trivial spherically symmetric vector fields (you can't) and nothing to do with Maxwell's equations. However, the waves can have a spherical character to them, as is the case with dipole radiation.

Maxwell's equations and wave equations


Familiar help action flavor

Question: My DM wants to know how (flavor-wise) my familiar does the help action. My familiar is a small animal (usually spider) hanging on my shoulder while I engage in melee combat. All types of flavor from fun and dumb to serious and edgy is really appreciated.
Comment: We don't really do idea generation very well here, you are probably better asking this on a forum.
Comment: Related and possibly useful to you: [Familiar and Help Action](https://rpg.stackexchange.com/questions/171874/how-do-i-go-about-convincing-my-dm-that-their-ruling-about-my-familiar-is-a-bit). Does your DM want to know this to establish if the familiar can use the help action in combat?
Comment: @SeriousBri: It's also worth linking to the relevant FAQ on [meta], here: [I've been told my question is better suited to a forum, but where should I go?](https://rpg.meta.stackexchange.com/q/5449/33569)
Comment: @V2Blast thank you, I can never find them when I want to link to them.
Answer: In general, the familiar can use the help action in combat
As explained in this Q&A, while the familiar cannot attack itself, it can take other actions, including the help action (page 192 PHB):

Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you. You feint, distract the target, or in some other way team up to make your ally's attack more effective. If your ally attacks the target before your next turn, the first attack roll is made with advantage.

There is no explicit demand that you need to have strong narrative support, so strictly by the rules, such flavor is not required.
However, as you can see from the answers in the linked Q&A, when you use the help acction  it is quite common that the DM asks for an in-game narrative justification for how the help is achieved to allow it. While the Help action is for combat, the rules for Working Together (PHB p. 175) outside of combat for example demand that:

A character can only provide help if the task is one that he or she could attempt alone

Many DMs (mine included) ban help in actions that the familiar may not be capable in by themselves. In this sense, it is already nice to allow the familiar helping with the attack action, when it cannot do so itself. (Although other than the Working Together rule, the Help action makes no such demand). In this case, if you cannot come up with a good explanation how the familiar sitting on your shoulder can feint an attack or otherwise distract the opponent, they may possibly rule that the familiar is unable to grant advantage. There are several options for you

You pick a familiar form that is more able to distract. While a spider sitting on your shoulder may have a more difficult time to do so, a flying familiar getting into the opponents face has a very simple way to distract them. The owl is the best option here, as it has flyby and does not provoke attacks of opportunity when getting away afterwards. The spell allows you to freely exchange the familiars form, for a cost of 10 gp in recasting it.

For a spider, it is more difficult to come up with a justification. Maybe it is a spitting spider (although the mechanics of the monster entry do not say so); maybe it feints jumping or scuttling onto the opponent, maybe the spider scuttling around your neck is distracting to the opponent. Maybe is is coating your blade with glistening spider poison. Maybe it is shooting out web strands that irritate the oppponent. Or maybe the spider is looking for and telephatically alerting you about weak spots in the opponent's defense as Kirt suggests. Or maybe none of that is convincing to your DM, and  they will rule you cannot grind advantage for melee attacks out of them.
Answer: In some other way
The Help action says (emphasis mine):

you can aid a friendly creature in attacking a creature within 5 feet of you. You feint, distract the target, or in some other way team up to make your ally's attack more effective. If your ally attacks the target before your next turn, the first attack roll is made with advantage.

Listing "All types of flavor from fun and dumb to serious and edgy" that your familiar might use to "feint [or] distract the target" would be, as SeriousBri comments, an exercise in idea generation and something we don't do here.  However, if your Tiny (not Small) spider is going to remain on your shoulder during the combat and not (say) jump on your opponent's face, its possibilities for Helping you are rather limited and worth a RAW review.
Looking at the find familiar spell, we can see that:

the familiar has the statistics [including the senses] of the chosen form, though it is a celestial, fey, or fiend (your choice) instead of a beast...Your familiar acts independently of you, but it always obeys your commands. In combat, it rolls its own initiative and acts on its own turn. A familiar can't attack, but it can take other actions [including the Help action] as normal...While your familiar is within 100 feet of you, you can communicate with it telepathically.

If the familiar is going to remain physically attached to you, the most relevant way that it can Help you is by using its own senses, independently of yours, and sharing that information with you instantly and telepathically.  In Combat, there are innumerable demands on one's attention, since not only are you watching the opponent you intend to attack, but you must also (PHB Chapter 7, "Hiding" sidebar):

stay alert for signs of danger all around

Narratively, your character is having the familiar watch for openings in your target's defenses when you are looking elsewhere, getting ready to jump out of the way when the enemy mage targets you with their Dex-save spell.  Alternately, while you focus on your opponent, waiting for the perfect time to strike, your familiar sits on your shoulder and uses its eight beady little eyes to make sure that no one is coming up behind you.  While you yourself are not seeing behind you, you have a trusted partner who will warn you if and when you need to spin around.  Because of this, you are able to exploit much more short-lived openings in your opponent's defenses, resulting in advantage on your next attack.
Comment: +1 that is a clever justification

Familiar help action flavor


iphone data synchronization

Question: I'm new to iphone development. I currently have an app on windows mobile that uses a local database on the device (sqlce) and the app is able to synchronize the data between the device and a remote database through a web service using microsoft sync framework.
Is this requirement feasible on an iphone app? Id like to build a version of my app on the iphone. I see that the iphone can use sqlite for storage on the device.
But does the sdk have something for data synchronization?
Answer: No, you have to use JSON or XML to get the data from your remote server via a NSURLConnection and write the code to synchronise the sqlite db on the iPhone. There are plenty of JSON frameworks for the iphone and for the XML route you can use NSXMLParser.

iphone data synchronization


Is Project Catalyst the only source of non-commercial funding for Cardano projects?

Question: If I have an idea that is not funded on Project Catalyst, where else can I find funding other than venture capital firms
Please disclose any affiliations (if you have them) when answering.
Answer: While Project Catalyst is for commercial and non-commercial Cardano projects, you are not limited to specific resources that fund only Cardano projects.
Venture Capital and non-commercial typically do not go hand-in-hand together. VCs have an interest in your company/project's success. They give you money so you (or one of your competitors who they also fun) can make them more money.
Depending on your project/company/organization you want to build, different avenues are at your disposal that have nothing to do with blockchain.
It also depends on your jurisdiction and whether you can apply for public money. Applying to grants (outside of Project Catalyst) and fundraising efforts are big parts of a non-profits. This question is a little bit too broad to give an accurate answer. If you can be more detailed what it is what you're trying to do (link to your proposal), you may receive more and better suggestions.
Answer: If you are looking for funds your own project I can only assume you are operating as a business entity, if you insist on not accepting VC money despite wanting to operate as a business entity then I would seriously suggest you check out this new funding modal, unique to and only possible using Cardano called an "Initial Stakepool Offering" or ISO.
https://sundaeswap-finance.medium.com/sundaeswaps-upcoming-initial-stake-pool-offering-iso-48fade1900a
In my humble view it radically changes the game when it comes to sourcing funds for blockchain based startups/projects because it taps into the existing innovative   staking mechanism built into Cardano, and your supporters funds are completely safe.
This is of critical importance and is the killer-feature of the ISO model because it creates a risk-free (minus fees collected approx. 5.5% APY that you would otherwise collect for staking) environment for supporters in direct opposition to the scam-ridden ICO funding model of the past. The fact that people can support you virtually risk-free creates a very rich and liquid startup environment where people are more than happy to throw some ADA around at different projects.
It also creates a much higher level of trust between the project and the supporters because once you have someone's money you lose the financial incentive to work as hard as possible to deliver. While the ISO model has built-in incentive by way of the supporters losing faith in a project that continually misses roadmap targets and will eventually undelegate their ADA, and only having to accept the loss of 5.5%~ APY that they would have otherwise earned. This is massive and simply cannot be overstated.
I am unaffiliated in any way with SundaeSwap directly, although I'm a firm believer in the funding model that they pioneered.


Suspected Spam Issue

Question: Recently I've got problem from sending email out, it's about relaying denied. After doing some checking I found that my ip is being blacklisted, because of spamming. I checked my maillog and I found that my mail server has send lots email I did not send. But they got no recipient from, how they manage to send from my mail server? How do I trace out who is the spammer and what can I do to block them? I check the relay most of it either come from China, Thailand or Indonesia.
Comment: Ensure you are running a recent Linux/Unix distro. Every distro for the last several years has a default mailserver configuration that disables open relaying. You're not running the old Red Hat 7.3 are you?
Answer: You have a security problem.  You either left the door wide open or somebody broke in.
Make sure your server software is up to date, and take the time to thoroughly read sendmail's documentation. You could be hosting an open relay which leaves you wide open. No one, however, can give you specific steps to fix your problem because there are many possible things wrong.
Comment: So they're coming from open relay? I'm not technical but afaik my friend has setup to block domain that's not in our list.
Comment: Whoever is responsible for your mail server and the technical details needs to spend some time studying the proper ways to configure it for security. Your original question is quite broad so it's difficult to pinpoint a specific problem.  Read the sendmail documentation (assuming that you are using sendmail).  Return with questions as they come up.

Suspected Spam Issue


WebDAV and sharepoint server subscription edition

Question: good morning, is WebDAV still working on SharePoint subscription edition? Because when I clicked Open with Explorer it is trying to use OneDrive instead of the UNC path.
i already added the site in Trusted Sites and used the IE compatibility mode.
also i installed the webdav publishing feature on the server
i tried this path \server.domain.org@ssl\DavWWWRoot\ too
but unfortunatly still not working
can you suggest a solution please or advice
thank you in advance
Comment: Are you using classic or modern experience?
Comment: classic experiance
Answer: I found the solution maybe it can help someone in the future :)
(my environnement: windows server 2019, sharepoint server subscription edition)

Enable WebDAV Redirector
Enable the WebClient Service to Automatic" Startup Type
Enable the Portable Device Enumerator Service to Automatic Startup Type
Disable WebDAV Authoring Rules on your site on the IIS
try to connect from \yourserver.domain.org@ssl\DavWWWRoot\


What are some good user login/authentication libraries or protocols to use with Python on Google App Engine?

Question: I've read elsewhere (http://forums.udacity.com/questions/6028436/bcrypt-not-suitable-for-pythongae) that bcrypt is not suitable for use on Google App Engine. What are some good ways to create a user signup/login system (with usernames/emails & passwords) without rolling your own when using Google App Engine for Python? Thanks!
Answer: The PBKDF2 algorithm available from the passlib library will do the trick.
It doesn't have some appealing properties of bcrypt such as being hard to speedup using GPUs but it is still a strong password hashing with a configurable iteration count.


Programming ATmega328p on external board with FT232R

Question: I am making a 100W AC-DC linear power supply, for which I want to show output Voltage and Output current on LCD display. I already used shunt resistor and voltage resistor to bring both values to analog pins on my ATmega328P in DIP socket, which has an Arduino bootloader on it. I want to programm my ATmega328P on the board without taking it off everytime and putting it into Arduino UNO board to just programm it and put it back, so how can I integrate a programmer onto board?
I intend to use the FT232R ic, which I think would work more than fine for this application.
On finished product I want to have a USB connector on the case just to update/correct the software.
Comment: If you want an USB connector, an Arduino Nano or 32u4 based Arduino may be a better solution.
Answer: I suggest use ICSP(In circuit serial programming) feature of the Atmega 328 chip. Grab the .hex file from the arduino IDE and a USB ISP external programmer to write the program to the chip. Here you will have to use a 6 pin header on your custom board to take out the pins which are used to program the atmega.
Comment: External programmers are cool, but if you want your end-user to connect to the board, you'll most likely want USB. But I agree that it is useful to have the ICSP header available, so you can put on the bootloader if you're making more of these boards.
Comment: That's correct paul. But here the OP has said that she plug the chip into an UNO for programming and then remove it to the target board. And she want to avoid that. In that case this is the simplest solution rather than building an UNO in the application.
Answer: I use an FTDI cable with my home-builds. Then the board doesn't need the interface hardware (it's in the cable) and the MCU doesn't need to be removed.
I put a 6-pin male header on the board to match 6-pin female socket my cables come with. The header is direct-wired to the Tx, Rx, +5, & Gnd pins. If you have an auto-reset circuit on your board, connect the RTS pins to that. Then, reprogramming is as simple as connecting your board and clicking 'upload'. Without the auto-reset circuit, you just hold the reset button while you click upload, count 3, and release the reset.
Update:
You can do it with only 4 pins on the board. If I understand correctly, just wire Tx, Rx, +5 & Ground of the Arduino to the 4 pins and replace the Arduino-end socket on the FTDI cable with one wired to match however you wired the board. If you use L-shaped male pins, they'll lie parallel to the board and won't add any height (above what is already on it).
Comment: Hmm..that doesn't sound as a bad idea, but I'd like to make only 4 pins onto the PCB and from there connect the USB cable panel mount. In other words, I'm searching for a schematics for USB cable - ftdi - atmega connection.
Comment: Check the schematics of the Arduino Nano, they are basically exactly the circuit you describe.


jsf-facelets forward bypass servlet filters

Question: For one week, i am playing with appfuse-jsf-basic but i noticed something. If i do not put  tag to my navigation rules, i can view a page that require ROLE_ADMIN with ROLE_USER rights. Then i understand something that facelets doesnt use "servlet.forward" methods for forwarding so filters does not catch facelets forwards in navigation rules. Is there any other way to use facelets with no-redirect  navigation rules and acegi(aka spring security).I searched all the forums but could not find a solution. Thank you in advance!
Answer: You can have a look at this library: http://dominikdorn.com/facelets/.


Uptime of a Windows machine

Question: How can one find out 'real' uptime of a laptop?
By 'real' I mean the time since turning it on and resuming Windows from hybernation state.
Answer: If just you want to know the time passed since the last boot, execute the bult-in command
 systeminfo

in a command line. Search for the "uptime" line.
Comment: Thanks for this great tip. The "System Boot Time" line gets me what I'm looking for.
Answer: EDIT: i just noticed your "after hybernation" requirement - sorry, I don't think this will take that into account. You'll need to work this out from reading the event log. Uptime is time since last reboot. A hibernation is not a reboot. If "uptime" could be defined to take hibernation into account, I would expect it to mean all time spent awake since the last reboot (meaning minus all hibernation time), not just the time since last hibernation.
I use the free psinfo tool from sysinternals (now owned by microsoft, and still free)
C:\>psinfo

PsInfo v1.75 - Local and remote system information viewer
Copyright (C) 2001-2007 Mark Russinovich
Sysinternals - www.sysinternals.com

System information for \\LAPTOP:
Uptime:                    0 days 11 hours 28 minutes 27 seconds
Kernel version:            Windows 7 Ultimate, Multiprocessor Free
Product type:              Professional
Product version:           6.1
Service pack:              0
Kernel build number:       7100
...

Grab it from \live.sysinternals.com\tools\psinfo.exe (you can even run it directly from that unc link).
Comment: You can filter the output - "psinfo uptime" shows only that.
Answer:
Windows Uptime (free from MS) might help you with that, but I'm not sure if it will give you info about 'after' hybernation: http://support.microsoft.com/kb/232243
I wonder if the default tools might help you (from cmd):
net statistics server or
net statistics workstation
Comment: 'net stats server' shows only timestamp of last system start
Comment: `net stats work`
Answer: I tried all the other answers but they just aren't showing "uptime" or infos I need.
This one works for me on my Windows 7:
wevtutil qe System /q:"*[System[Provider[@Name='Microsoft-Windows-Power-Troubleshooter']]]" /rd:true /c:1 /f:text > wake.txt

Run that command prompt and then look for a txt file on current directory
This uses the "Windows Event viewer" and the > wake.txt means it will save to a text file called wake.txt
Answer: Sometimes the other uptime command display a time that is not correct so I use this command to display the LOGON TIME
query USER

or shorter even:
quser

which prints something like:
C:\Users\eflorinescu>query  USER
 USERNAME                 SESSIONNAME        ID  STATE   IDLE TIME  LOGON TIME
>eflorinescu              console             2  Active    2+23:44  5/7/2018 8:25 AM

Comment: Isn't this solely **SESSION** uptime?
Comment: @ChrisMarisic If you are talking about the user session  yes it is the user session uptime

Uptime of a Windows machine


Density of states for free particle

Question: I am asked to find the density of states for a free particle as a function of $|p|$, $\Delta|p|$ and $\Delta V$. I also have the expression for the number of states $\Delta\Omega(p) = g(p)\Delta p = \frac{V}{h^3}\Delta p_x \Delta p_y \Delta p_z$. So how is $\Delta |p|$ different from $\Delta p$, and what do I do with $\Delta V$? $ p$ is momentum, $V$ is volume and $h$ is Planck's constant.
Comment: As a start please define your symbols.
Comment: @Farcher edited.
Answer: Momentum $p$ is a vector quantity so:
$$p=(p_x, p_y, p_z)$$
$$\Delta p=(\Delta p_x,\Delta p_y,\Delta p_z)$$
However $|p|$ is length of the momentum vector thus a scalar quantity:
$$|p|=\sqrt{p_x^2+p_y^2+p_z^2}$$
I am not quite sure what $\Delta V$ is but I think in this case $\Delta V = V$. You already have density of states as a function of $p$. It is the number of states in cube element $\Delta p_x\Delta p_y\Delta p_z$.
If you want a function of $\Delta|p|$ you need to get a number of states in thin spherical shell of radius $|p|$ and thickness $\Delta |p|\to 0$. Simply transform the cube element $\Delta p_x\Delta p_y\Delta p_z$ to radial element $\Delta |p|$.
You should get
$$\underline{\Delta p_x\Delta p_y\Delta p_z=4\pi |p|^2 \Delta |p|}$$
To clarify the difference between $\Delta p$ and $\Delta |p|$ just look at this:
$$\Delta p=p_2-p_1=(p_{2x}, p_{2y}, p_{2z})-(p_{1x}, p_{1y}, p_{z1})=(p_{2x}-p_{1x}, p_{2y}-p_{1y}, p_{2z}-p_{1z})=(\Delta p_x,\Delta p_y,\Delta p_z)$$
$$\Delta |p|=|p_2|-|p_1|=\sqrt{p_{2x}^2+p_{2y}^2+p_{2z}^2}-\sqrt{p_{1x}^2+p_{1y}^2+p_{1z}^2}$$
Comment: $\Delta V$ is an element of volume. We calculate the density of states in 6 dimensional configuration space. A cube element in this space should be $\Delta p_x \Delta p_y \Delta p_z \Delta V=\Delta p_x \Delta p_y \Delta p_z \Delta x \Delta y \Delta z$. So I think the number of states should have been given as follows: $\Omega(p,V)=g(p,V)=\frac{1}{h^3}\Delta p_x \Delta p_y \Delta p_z \Delta V$

Density of states for free particle


How to print file directly, circumventing the print dialog?

Question: How to print in single command/shortcut (like Ctrl+P) without showing the print configuration  window?
Comment: @raghulrnair I suspect there might not be any way to do this *in general*, but that you could do it for particular applications, or at least those that support programmable macros (like LibreOffice). Are there specific programs you most need this for?
Comment: @hakermania This isn't really a duplicate. The OP asks to print from any program without the standard dialog, *not* to print a PDF directly.
Comment: i have a network project for billing  so it is difficult to select and print printer and printing option, is their any print config file? how to congig and where it is located
Comment: @ObsessiveFOSS that's why the 'possible' word exists ;) I thought that via the command the print dialog is not being shown.
Answer: There's only one way to do this, and it's a bit of nuisance. If you start Chromium with this extra option,
<code>chromium-browser --kiosk-printing
</code>
you shouldn't get a print dialog when you try to print. If you ever need to access the print dialog, however, you'll have to completely quit Chromium and restart it without that option.


Node paths come through empty unless view result is programmatically changed

Question: Task: to retrieve a list of nodes in JSON format including their aliases generated by Pathauto module. The configuration of my view is this:

Problem: path fields come empty - they won't include original Drupal path to it nor an alias generated by Pathauto:

The current solution I've got is to programmatically amend view's result in the following way:
<code>function my_custom_views_pre_render(\Drupal\views\ViewExecutable $view) {
foreach($view->result as $value) {
    $url = \Drupal\Core\Url::fromRoute('entity.node.canonical', ['node' => $value->_entity->get('nid')->value], ['absolute' => false]);
    $url = $url->toString();
    $value->_entity->set('path', $url);
}
</code>
}
And that populates the path fields:

I'd like to know if there is a way to avoid the hook and make views return node paths without it, or is it normal Drupal Views behaviour?
P.s.: If I chose "Fields" instead of "Entity" in the Format section in the Views UI, it does return me the correct paths. However I want to get the full entity due to extensive data it consists for later consumption.
Thanks!
Answer: Put Show on field, then remove "title" field and add Path field

and if you want result be Absolute Url  on Rewrite secion Check Use absolute link (begins with "http://")


Brain teaser Strategic choice...

Question: $X$ and $Y$ are playing a game. There are $11$ coins on the table and each player must pick up at least $1$ coin, but not more than $5$. The person picking up the last coin loses. $X$ starts. How many should he pick up to start to ensure a win no matter what strategy $Y$ employs?
Comment: What do you think? Have you ever encountered a similar problem?
Answer:
$X$ takes $4$
$Y$ picks some amount: $c$
$X$ then takes $6-c$
$Y$ has no option but to take the last one.
Answer: If $X$ takes $4$ at the start, then there will be $7$ left.
$Y$ can then take any between $1-5$. Let $y$ be the number of coins $Y$ picks up. Then $X$ can pick up $6-y$ coins and there will be one coin left on the table, which $Y$ has to pick up. We know $X$ can pick up $6-y$ coins because $1 \leq y \leq 5$, therefore $1 \leq 6-y \leq 5$
Answer: No matter what Y needs to be left with only $1$. Since the most someone can take is $5$ and the least someone can take is $1$ then in order to win, X needs to make sure he is picking when there are between $1+1=2$ and $1+5=6$ coins left. So to do this in the least amount of steps possible, X needs to start off by taking $4$ coins. Then there will be $7$ coins left. After Y's turn, there will be guaranteed between $2$ and $6$ coins left. Then X just needs to take $5$ coins and Y will be forced to take $1$ and X wins.
Answer: You want your opponent to have exactly 1 coin on their turn, so on your turn you could have anywhere from 2 to 6 coins. In order to force your opponent to leave you with this many coins, they should have 7 coins. So if there are eleven coins you should take 4 as your first move.
Answer: A player facing $n$ coins can force a win iff there exists $1\le k \le 5$ such that a player facing $n-k$ coins cannot escape a loss.
Clearly, $n=1$ is a lost position.
Therefore $n=2, 3, 4, 5, 6$ are won positions.
Therefore $n=7$ is a lost position.
Therefore $n=8, 9,10,11,12$ are won positions.
One readily sees that this pattern continues and a position $n$ is lost if and only if $n\equiv 1\pmod 6$. Therefore $n=11$ is a won position - and the (only) winning move consists in going to the lost position $7$.
Answer:
$X$ must not reach the state of $2\dots6$ coins left on the table at $Y$'s turn
Otherwise, $Y$ can take $1\dots5$ coins (leaving $1$ coin on the table) and win
So $X$ should take $4$ coins off the table, and leave $7$ coins on the table
Then, however many coins $Y$ takes, $X$ can take the remaining coins minus $1$

Brain teaser Strategic choice...


Using PWM signal to decrease power of laser over time

Question: I'm trying to turn a laser on and off with an external button. When I press the button, the laser should turn on. When I release the button the laser should turn off. However, I don't want the laser to turn off immediately. I want it to turn off linearly over 500 ms. I'm using PWM to alter the strength of the laser over time. However, will my laser power increase and then decrease in the extremely short time segments due to PWM fluctuation? Will it even be able to execute this reduction of power?
Answer: I dont know your circuit but...
Do you effectively want to use an RC filter to reduce PWM fluxuations so that the laser sees an analog voltage which will translate to a power (presumably)? - that will avoid the pulsing of the laser, but I did believe that the pulsing at full voltage was neccersary in most laser drivers - please post a schematic... Anyway if you want this to be less of an issue if an RC filter is not for you you could increase the PWM frequency (google is your friend) on the arduino...
To have it turn of slowly if your using analog, the RC filter could possibly have large enough capacity to slow the laser turn off. It will also effect rise time so suitable values for R and C will need to be found to suit. Otherwise you could dial down the PWM gradually before hard power off in the arduino software, by initiating a loop which gradually reduces power with time.
Somewhere to start anyway :)
Comment: This is my code to gradually reduce power over time:
void loop() {
int stateButton = digitalRead(onButton);

  if(onButton ==1){

    digitalWrite(Laser, HIGH);

  }
  else{
    for(int i = 255; i>=0; i--){
      analogWrite(Laser, i);

      delay(500/255);
    }

  }           Would this loop through continuously? Would the power descend always loop through the descent even though I didn't press the power button?

}
Comment: Sorry my coding is not great so without formatting I find it hard to read your code.
I would do it differently myself, using an if statement which ran the pwm loop when you have activated its variable.


Are timing attacks for PHP used in practice?

Question: I'm curious, to what extent are passwords exploitable if the underlying password comparison is vulnerable to timing attacks. My main concern is that internet speed continuously varies, webserver response times change depending on server load, etc.
Answer: If the timing difference is in plaintext password comparison, it is not really feasible to do this over the Internet. However, it is often possible for the attacker to get access to a computer in the same network, or even to a VM on the same hardware, by hosting his attack with the same hosting provider as the target web site.
If the site uses hashed passwords and compares the hashes instead of the plaintext password, this timing attack scenario doesn't apply anymore.
Comment: The last sentence is not entirely true. Beware of comparing hashes with '===' as it is still sensitive to timing attack

However having a comparison that always takes the same amount of time to compare the two strings is safe against timing attacks


What beracha do you make on Golden Puffs?

Question: Golden Puffs is a honey glazed puffed wheat cereal.
I'm looking for the sephardic minhag.
Preferably an answer from Rabbi Ovadia Yosef.
I've narrowed it down to either adamah or mezonot.
Comment: In Rav Marlow's Berochos guide, which is based on the Shulchan Aruch Harav, he says that it's Ha'adama and borei nefashos, but it's preferable to eat it in a meal. I assume making a mezonos and ha'adama on two things that definitely have those berochos would be the same thing as having it in a meal. As for whether sefardim make mezonos or ha'adama, i don't know, but if you want to be machmir, then have it in a meal.
Answer: The Shulchan Aruch O.C. 208:4 writes:

אכל דגן חי או עשוי קליות או שלוק והגרעינין שלמים אינו מברך אלא בורא פרי האדמה ולאחריו בורא נפשות.
והתוספות נסתפקו אם יברך לאחריו ברכה מעין שלש ולכך כתבו שנכון שלא לאכלו אלא בתוך הסעודה ויפטרנו ברכת המזון
If you eat raw or roasted wheat ... and it is whole, the blessing is Ha'adama and Borei Nefashos.  However, Tosefos entertained the possibility that it should get a Me'ein Shalosh (Al Hamichya) and therefore wrote not to eat it except in the middle of a meal, in which case it is covered by Birkas Hamazon.

Puffed wheat is made by roasting the wheat kernels in a popper.
Generally Sephardi custom follows the opinion of the Shulchan Aruch. Therefore, I would assume the blessing is Adama and Borei Nefashos, and if you want to be extra-careful, eat it in a meal.


Generators for this ideal

Question: I have a ring $R$ unitary and commutative with four elements and characteristic $2$. I have $$I=\{f \in R[X,Y]; f(t,t^2)=0\ \forall t \in R\}.$$ I have to find a finite number of generators for this ideal.
I have thought to use $\langle x^2,y \rangle$, but I can't show all the $f$ that are in $I$ are generated by $\langle x^2,y \rangle$, in fact I'm not sure if this example works. I thought it could because of the characteristic.
Comment: $\langle x^2, y \rangle$ can't be right because $x^2$ and $y$ are not in the ideal.  Also note that there are 2 different rings $R$ that satisfy your conditions, and the answer will be different for the 2 rings.
Comment: yes, you are rigth..I know there are differnet rings with this property8i thougt 3 not 2) but I dont know how could I start..there is not an usual  procediment??
Answer:
Start by finding one nonzero polynomial $f$ satisfying $f(t, t^2) = 0$ for all $t \in R$.
Taking the quotient $R/I$ where $I$ by the ideal generated by the $f$ you found in step 1.
Repeat steps 1 and 2, with $R$ replaced by $R/I$, until you can't find any more nonzero polynomials in step 1.  You will have to prove that there aren't any, of course.

At some point, you will need to break the problem into 2 cases, depending on what $R$ is.  There are 2 commutative unital rings of characteristic 2.

Generators for this ideal


Create NLA transition with Python

Question: Is it possible to create transition between clips with python?
Answer: This is an example of how to do it, using bpy.ops.nla.transition_add
import bpy

# Generate an override that can be used for this call.
win = bpy.context.window
scr = win.screen
areas  = [area for area in scr.areas if area.type == 'NLA_EDITOR']
regions   = [region for region in areas[0].regions if region.type == 'WINDOW']
override = { 'area': areas[0], 'region' : regions[0] }

# Replace this line with one that selects the object that has the NLA Tracks
object = bpy.context.active_object

# Replace this line with one that selects the NLA Track you want.
track = object.animation_data.nla_tracks['NLaTrack']

# Replace the next two lines with ones that select the desired strips.
# They must be adjacent.
# No other strips should be selected so you may have to deselect all first.
track.strips[0].select = True
track.strips[1].select = True

# Add the transition, using the override calculated earlier.
bpy.ops.nla.transition_add(override)

The key is that you have to select two adjacent NLA strips and that the bpy.ops.nla.transition_add call needs a context override.
3.2 Update
Context overrides are deprecated in Blender 3.2 and are scheduled to be removed in Blender 3.3  The replacement is temp_override. The manual has examples of how to use the new function.
Comment: Thank you Marty! But is there solution without selection these clips? Something similar to: bpy.types.NlaStrips.new( ... )

I am creating simple addon for duplicate whole NLA from one object to other. I can easily copy all clips with settings, but I don't know how to copy the transitions.

It is releated to this: https://blender.stackexchange.com/a/163875/1910
Comment: bpy ops tend not to be very flexible and there's really no way to add a transition without knowing where it goes, as far as I know. Unfortunately "where it goes" is between two selected strips. But copying might be a different problem. Maybe ask a separate question about copying between two tracks?
Comment: @Cenda I just added an answer to the other question that should handle your transition case.

Create NLA transition with Python


Good definition for "coherence"

Question: I'm trying to tell someone his code is not "coherent" in the sense that it serves multiple purposes. I don't think I can explain it very well, so I'm looking for a good reference and/or definition.
Comment: You ought to tell him his code is not cohesive!
Comment: I'm voting to close this question as off-topic because it asks the readers to find a word in the English language instead of an appropriate technical solution to a problem.
Answer: I think the correct term is cohesion.

In computer programming, cohesion is a measure of how strongly-related and focused the various responsibilities of a software module are. Cohesion is an ordinal type of measurement and is usually expressed as "high cohesion" or "low cohesion" when being discussed.
Modules with high cohesion tend to be preferable because high cohesion is associated with several desirable traits of software including robustness, reliability, reusability, and understandability whereas low cohesion is associated with undesirable traits such as being difficult to maintain, difficult to test, difficult to reuse, and even difficult to understand.
Comment: Ah. It seems Google can't pass the Turing Test... yet. No wonder I couldn't find the answer there! Accepted for the link.
Answer: I had Code Complete by Steve McConnell next to my computer (ie the programmers bible) with the page open explaining cohesion so I thought I'd share,

Cohesion arose from structured design
  and is usually discussed in the same
  context as coupling. Cohesion refers
  to how closely all the routines in a
  class or all the code in a routine
  support a central purpose-how focused
  the class is. Classes that contain
  strongly related functionality are
  described as having strong cohesion,
  and the heuristic goal is to make
  cohesion as strong as possible.
Comment: +1. Add some links though. Code Complete website is here http://www.cc2e.com/, and why not link "programmers bible" to this SO question, where it wins by miles http://stackoverflow.com/questions/1711/what-is-the-single-most-influential-book-every-programmer-should-read
Comment: @CodeKiwi You have _Code Complete_ open next to you at all times? That's a little creepy. Thanks for the reference though!
Comment: haha, No I am currently reading through it, it probablly wouldnt hurt to do so though, its a great book.
Answer: I use the term "separation of concerns" to explain this while refactoring. Often when code is fairly new, things will get lumped in together as the separate concerns are not clear at first.
One easy way to illustrate this to your co worker would be to ask them to write test cases for the code. This should illustrate that the code is not clear or coherent.
Another good phrase to use is that functions/objects "should do one thing, and do it well", this has implications in everything from the object/method names to the overall architecture of the system.
Answer: In addition to the answers given so far, a simple way to think of high cohesion is lack of duplication of functionality, and clear seperation of related functionality into distinct modules, components or classes.  Thus if you want a function similar to another function, and you cut and paste and subsequently modify a copy of the code, you are reducing cohesion.  If you modify the the original to handle the new case, where the new case is clearly related to the existing functionality, you are increasing cohesion.  Put another way, if your program has to do a given thing, no matter how times or in how many places, for maximum cohesion there should only be once piece of code that does that thing.  At the same, a given class, module or component should have a single area of responsibility.  Lumping unrelated functionality into a single class or component also reduces cohesion.
As CodeWiki says, cohesion is typically discussed with coupling, where the two can act in opposition to one another, particularly where strict interfaces aren't carefully planned.  Many of the googled articles on cohesion relate to OO design, but cohesion and coupling are not restricted to OO.
Comment: Wouldn't generalizing a function make it _less_ cohesive in some cases? I think that's the problem with my colleague's code: it tries to accomplish to much instead of "doing one thing well", as suggested by another answer.
Comment: Sure, there is a fine line between unncessary replication and over generalisation.  The former is regularly the problem as it is so easy to achieve.  Your point is valid though, and I've edited my post slightly to cover your concerns.
Answer: Marked by an orderly, logical, and aesthetically consistent relation of parts; "a coherent argument" - from http://www.websters-online-dictionary.org/definition/coherent

Good definition for "coherence"


Cold hands due to cold/wind

Question: What is a good way to not have my hands/fingers freeze on bike rides in the cold/wind? I have a pair of gloves, but it doesn't fix the issue. Is there a better way than just to get a really thick pair of gloves that will be unwieldy.
Comment: I use leather gloves; they work very well for keeping out the wind
Comment: Some kinds of gloves are very bad for winter cycling, some answers below elaborate that.
Comment: I'm pretty sure this question has been asked before.  Perhaps someone can dig up the thread.
Comment: Is there a gap or an overlap between your sleeve-cuff and your gloves ?
Answer: The most important thing is to make sure your core temperature is high enough.  As your body begins to chill, it pulls blood away from the extremities, to maintain its core temp.  Often times cyclists will think "my core temperature feels fine, but my hands are cold" so they think they need warmer gloves, when in reality they need another jacket/vest/jersey/base layer.
Also, remember body heat is generated in your torso, and has to be piped to your hands.  If, for example, you were riding with bare arms, and giant oven-mitt gloves, your hands would still get cold, because the blood would have lost too much of its heat before ever reaching your hands.  Again, long-sleeved jacket/jerseys, base layers, and arm warmers can all help significantly with keeping hands warm.
Good gloves are important to keeping your hands warm, but they're just one part of the chain, and if any of the pieces are missing, not even the thickest, warmest gloves in the world will stop your hands from getting cold.
Comment: Hands and feet are the natural choice from our thermoregulator system to fine-control temperature, and are the first ones to suffer when the body needs to prevent heat loss on cold days. For that reason, after they get cold, it is very difficult to get them warm "from within" after vasoconstriction ensues, even if you have warm core as @prototoast said, because the warm blood doesn't get to the skin easily. Worse even on bikes, where the fingers are so exposed to cold wind.
Comment: If your circulation in extremities cuts off very quickly and takes a long time to come back, you should speak to your doctor and ask them about [Raynaud's phenomenon](http://en.wikipedia.org/wiki/Raynaud%27s_phenomenon) - it's a problem that a lot of people suffer with, including me. There are a lot ways to deal with it without requiring medication, including dietary changes, and it can really help when cycling or walking in the cold.
Comment: I have Raynaud's too. I do not know what changes to make though to help keep my fingers from freezing
Comment: I usually cycle with bare arms and warm gloves: if I need to cool myself then it's easier to push my sleeves up than to take my gloves off. Also my arm is bigger than my fingers, so it stays warm more easily.
Answer: Look for gloves made with a Windstopper material. I have some pretty thin gloves made with this and stay warmer than my thicker gloves because they stop the wind so well. You may want to look at lighter weight running gloves made with this as I find them a little more pliable. Most I have seen are not waterproof though.
Answer: Probably you are looking for bar mitts (pogies).
HOWEVER -- until recently I wanted to buy them, 4 months ago I had a nasty accident in comfortable conditions, just pure bad luck, that's all. From that point on I said "no" to any device that attaches me to the bicycle -- the reason is, in case of accident it is a split of the second, when you can fall on the ground and roll away, if you are attached you hit with entire force, and such static hit is too dangerous.
Getting back to gloves, since I have the same problem, I ended up with two gloves -- thin one, internal, and second one, lobster type.
Comment: Macias; that's interesting, because I've always understood the best thing to do in most cases during a crash is to keep your hands ON the bars--this prevents the natural reaction of reaching an arm out, which is what leads to so many broken collarbones. That, and allows you to 'tuck and roll' much better!
Comment: @Darren Cope, how do you **roll** with your arms on the handlebar? With your entire bicycle with you?
Comment: Macias; Well, essentially it's not really a 'roll' so much as a 'tuck' - the main idea being to avoid sticking your arms out and breaking a collar bone.
Comment: @Darren Cope, I didn't say anything about sticking your arms out -- my point is in case of the crash your bike works like debris and at the same time stopper. The sooner you are free, the better. So having anything which ties you to bike (SPDs, pogies) is dangerous.
Comment: I don't think that pogies holds someone to a bicycle anymore than a pillow holds one to a bed.  You might have seen pogies where people pull the wrist cords too tightly which is not recommended.
Answer: If you check any local outdoor retailer(basspro shop,cabellas,ems,dicks sporting goods) etc.They sell chemical hand warmers.They are basically a pouch filled with iron filings that heats as the pouch is exposed to the air.They will last about 10 hours(ride to work and ride home time for most of us).They cost about one dollar US. Place the pouch on the back of your hand as that is where the blood vessels are.If you are commuting and the ride is fairly short try preheating your gloves on a heater before you leave.Another suggestion from a skier buddy of mine is to apply muscle rub to your hands. I would use the odorless variety,it stimulates the circulation increases blood flow and keeps your hands or feet warm.
Answer: One option I don't yet see between the excellent answers above is this:
If you have fixed the wind issue you still lose a lot of heat in your hands through your handlebars. The rubber grip usually provides some insulation, but the metal of your handlebars is highly heat-conductive and constantly getting cooled by the entire bike. So in cold weather you are constantly holding on to a frozen stick that is very good at conducting heat away from your hands. Some additional padding on the handlebar side of things can greatly reduce that. Cork, or cork-like materials are very good at it. Unfortunately most options a know of are not very durable, so they'll only last a winter or so.
Windstopper gloves and better handlebar insulation keep my hands warm in subzero temperatures where just the gloves were not enough.
Answer: You might want to try to get some Pogies. These cover your hands and the bars, and can help a lot in keeping your hands warm.
Comment: @VladimirFГероямслава fixed the link. Found something that should be more permanent than a product page.
Answer: First off, get some "glove liners".  These are thin polypro gloves that go under other gloves, either regular cycling gloves or heaver winter gloves.
They provide an extra layer of insulation, and, in addition, you can remove the outer gloves and leave on the glove liners while working on the bike -- they're thin enough that they don't interfere with dexterity.
Answer: I use fingered gloves with electric heating. The model I use, Snowlife Heat GTX, has enough battery power for the two 40 min rides even at full power for -5 C, so I do not need to charge at work. There are also two reduced levels available. The gloves work well not just when it is really cold but also around zero. I never had courage to let them get really wet but they handle limited humidity also very well. My model also has insanely bright red LEDs to indicate they are on, these work nice when giving hand signals late evening. I also like the possibility to shut down the heater quickly without stopping when on the second part of my ride I get warm enough from myself.
I previously tried several types of other gloves types but on E-bike at 20 km/h just gloves gets not enough at +3 C or below. I understand it is quite a high end solution, and expensive, but the price of the yearly train/bus ticket that is saved may give the sufficient budget.
Answer: I'm very fond of my Pogie lites https://bikeiowa.store/products/pogielites?variant=8136388804709
I have gone down to the low 30's/0C wearing fingerless gloves, inside slightly larger soft leather gloves, inside the pogies. No complaints, pain or fatigue.
Answer: There have been excellent answers already, and I agree with most of them, specially the physiology of Prototoast, the pros/cons pointed by Macias, and the windstopping need pointed by Glenn (+1 for them).
I have used some gloves which were terrible, although thick, because they don't stop the wind. Thick knitted gloves are the perfect example.
Currently, in winter, I use a glove bought in a motorcycle store, which is quite similar to ski gloves: a nylon-like external layer, and a fleece-like internal layer. They are not so thick as ski ones, though.
You have to get used to the reduced motricity and sensibility, and most probably you will drop your keys when getting home, but with time even taking money bills from the wallet becomes relatively easy. But now my fingers get HOT while going fast to work in order to make the body warm. When I take the gloves off at the destination, no way I suffer from "hard fingers".
I like the idea of mitts/pogies, I used them with motorcycle and they work very fine specially in rain, but since the handlebars on commuter bikes are already cluttered most times, and unlike motorcycle the hands get some warm blood from the body, I think these gloves are already fine on a bicycle.
Answer: There is no one pair of gloves that will solve this problem for all temperature ranges for all types/durations of riding.
It is very important to block the wind and provide insulation, but if you do that "too well" your hands will sweat and the moisture will subsequently increase heat transfer to the outside and your hands will get cold in short order.
Here's what I do...

For cool temps (well above freezing): long finger "track" gloves, Giro Monaco
For cold temps (near freezing): Gore-tex gloves
For very cold temps (well below freezing): I don't, but those that do use some combination of glove liner, insulating layer, wind shell, and neoprene "handlebar cozy"

I had once thought that "lobster-style" ski gloves would be the ultimate gloves for cycling at all cold temps, but I was bitterly proven wrong. Gloves like that work great the first half hour or so, but the moisture build-up eventually made my hands unbearably cold.
Answer: If you have flat bars, tearing a hole in the corner of a ziplog bag to place over the handlebar grip gives you a mighty cheap pogie.
I find that fleece gloves, especially fleece flip-mits with polypro liners below them, can warm up very well.
Hand and foot warmth is highly dependent upon good circulation. Elastic around the wrists can make your hands colder by constricting your circulation. Also, increasing your core temperature is a good way to keep you limbs warm as well...so adding a fleece vest under your windbreaker can also be rather effective.
Wool long underwear is easily as effective as polypro long underwear and doesn't get a sweat funk as quickly, and I would suggest this as well.
Answer: Cold hands?
The ski patrol guys around here get cheap, thick, leather, insulated gloves at Target. (Or some other commodity department store.)
They're cheap and work for the winter. Of course, you can go for the nice cycling gloves. Several years back, Pearl Izumi had these wonderful winter cycling gloves. I wore out 2 pairs and when I went to buy a third pair, the model had been discontinued. So, I settled for another brand at the time. Cold hands for $50!
Anyway later on, I was chatting with a fellow cyclist in the bike locker room at work and complaining about cold hands. He was using these insulated, leather, utility work gloves. He got the idea from the local ski patrollers. $15 later, I quit having cold hands on the commute. The key is to pick ones that offer adequate dexterity.
Answer: In addition to the other answers, I find that the key to having warm hands is making sure that I keep my arms really warm - because if your arms aren't warm, then your hands have absolutely no chance of being warm.
To this end I often put on an extra pair of cycling arm-warmers underneath a long-sleeved jersey/jacket, which does the job very nicely.
There is also at least one commuter bike for sale in the UK which comes with heated grips - whilst these are very popular on motorbikes it's pretty rare to see them in the cycling world.
Answer: I think that something the question and answers are both missing is: Which winter are you referring to?  The winter in my area typically can get to -20F/-29C during the day which makes all other solutions here useless or wasteful (single-use disposable heating pads should be for emergencies).  The only two solutions I've found are dependent on your handlebars.  I've used US Military Surplus Air Force mittens comfortably from 30F to -30F.

These things would be in airplane ejector seats in case pilot was stranded in arctic.  However, for massive mittens you must have a single speed bike or twist shifters, all others are too difficult to manage.  I never had problems with brakes.  They also have a long string that ties them together that I keep over the back of my neck, so when my hands are too warm I can easily take them off while riding.
Pogies (known by brand name Bar Mitts) are also very functional, but using odd shaped handlebars requires buying odd shaped pogies.

However, if your bike is left in an unheated environment, your hands will always be fighting the coldness of the bars and levers underneath, as will the inside of the pogies be cold when your ride begins.
Comment: Aside - you can also get pogs / bar mitts for drop bars.

Cold hands due to cold/wind


Spotify won't open again after minimizing

Question: When I first launch Spotify it's fine. The GUI window comes up and I can play music. But if I close Spotify, so it's running in the background, I can't open the GUI window back up. It does continue playing music though.
The icon is still in the tray. If I right click the tray icon and click 'Show Spotify' it won't show. But clicking the tray icon again shows 'Minimize to tray'. The tray icon keeps toggling between these two options, with nothing actually happening.
From the try icon and can exit Spotify, and that works. I can then launch Spotify again and at first the window will come up, but after closing it the same issue happens.
If I click to launch Spotify from the applications menu nothing happens.
I am using Pop!_OS 22.04 jammy (x86-64). I was using the default Pop OS version of Gnome, but today I decided to install Cinnamon. Spotify worked perfectly fine until installing Cinnamon. But this problem does still exists when switching back to gnome.
I've tried installing Spotify through the Pop Store and through snap, but the problem persists. When I launch Spotify from the console, these message show up.

I don't know how to interpret the above error messages, or if it even relates to this issue at all. I haven't been able to find any solutions online, I just want to be able to open Spotify again If I minimize it. Any help or advice will be greatly appreciated.
Comment: Does it work if you minimize instead of closing? What if you go to the settings and disable the "Close button should minimize the Spotify window" option?
Comment: Yes I can minimize it instead of closing it, but I'm accustomed to having it running in the background and would like to solve this bug if possible.

I can disable "Close button should minimize the Spotify window", and it does exactly what is should. It will close instead of running in the background. On turning it back on the issue above still persists.
Comment: I did not change desktops and the issue appeared after an update of Spotify.
Answer: Today I've got an update of the Spotify app to version 22.214.171.1247. Now the app window re-appears, when I click on the icon in the task bar.
Comment: You're right, the latest update has fixed it for me as well.


Setting a pattern for a cell-background in Indesign using cell styles

Question: I would like to set a patterned background (ex: hashed, spotted- effects that are easily done in Word) to some cells in a table in InDesign CS6. Even a gradient would do the trick, but I see the gradient is set to scale the whole table, not the cell alone. I need a solution that can be set into cell styles, not done manually. Also, the width and height of each cell may vary so using a background image is not a good solution. What can you suggest?
Comment: Hi user2069532, thanks for your question. Could you tell us what you tried that didn't work? Could you add an example visual of what you tried and what you're trying to achieve? Always good to show some effort, and your chances for a good answer increase. If you have any questions, please see the [help] or ping one of us in the [chat] once your reputation is sufficient (20). Keep contributing and enjoy the site!
Answer: You could use the diagonal line options.... Table > Cell Options > Diagonal Lines

While a bit limited, it would offer some variations, especially if you use color in conjunction with line directions.
Comment: Thanks, good idea. I really had in mind authentic stripes that can be edited how wide etc but this is definitely better than nothing. I appreciate the response.