What can someone vaccinated in the EU use when asked for a "vaccine passport" in US restaurants/venues?

Question: From November 8th, EU citizens can enter the US again and since the airlines will check COVID-19 PCR test and vaccination prior to boarding, I assume that they will just accept the digital EU vaccination certificate (QR code). At least on departure from an EU airport they should even be able to actually scan the QR code and verify that the certificate is genuine. But what kind of proof do I need in stores, restaurants etc. in the US? They might not be familiar with the digital EU certificate, so I can imagine that the smartphone app that I use at home will not be accepted. Will the airline provide some kind of document that I can use during my stay?
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/131183/discussion-on-question-by-niko-what-can-someone-vaccinated-in-the-eu-use-when-as).
Answer: Your digital vaccine certificate from the EU should work fine, though I'd bring a paper printout too just in case. For example in King County this is directly addressed in the vaccine passport health order:

What is considered proof of vaccination?

CDC COVID-19 vaccine record card or photo of vaccine card
Printed certificate from MyIRMobile.com
Other official immunization record from within or outside the U.S., including from your health care provider. A photo or photocopy of this
card is also acceptable.

As you can see, the CDC card is just one option and they explicitly allow foreign documents. For NYC the rules are similarly friendly to alternative documents:

For proof of vaccination, you can use:

CDC Vaccination Card. A digital photo or photocopy of this card is also acceptable.

NYC Vaccination Record or other official immunization record, including from your health care provider. A digital photo or photocopy
of this card is also acceptable. If you are unable to get this record,
call 311.

Businesses likewise acknowledge this, for example a restaurant in NYC has the following policy:

For International Guests:

Please bring a copy or your vaccination record and valid photo ID. Documentation showing that a guest received any of the vaccines
approved for emergency use by the World Health Organization will be
accepted.

Finally remember that not all states have a "vaccine passport" program. Around half of them went as far as to ban them and only a handful currently require them statewide. So depending on your destination you might not have to show your vaccine card at all.
Comment: @Relaxed as a corollary, this represents a difference between US and European bureaucracy - paperwork requirements are generally very lax. The CDC card itself is just a plain piece of paper unlike the European cryptographically secure QR code.
Comment: @Relaxed updated with a different text from the county website, thanks
Comment: @NeanDerThal I'm not sure what you mean?
Comment: @JonathanReez The FAQ on King County's website mentions "states" (as in US state, a component of the US) or "county" (no "r", a sub-state administrative division in the US) and doesn't mention foreign documents at all.
Comment: "paperwork requirements are generally very lax": which caused no end of worry about whether my wife's and my CDC cards would be accepted in various European jursidictions.  Mine has a stamp; hers doesn't.  Hers has some datum that mine doesn't, I don't remember which.  Fortunately, they have both now been converted into EU digital passes.
Answer:
But what kind of proof do I need in stores, restaurants etc. in the US?

A friend of mine was in this situation when visiting Washington state and simply showing a picture/screenshot of the certificate on his phone worked all the time for restaurants/bars/clubs. The restaurants/bars/clubs were checking his name on the vaccine certificate as well as the vaccination, and sometimes looked at whether his name was matching the ID. Nobody checked if the certificate was genuine and the paper version was never asked. He went to ~20 restaurants/bars/clubs. Some don't require vaccination proof.
Comment: This lack of actual checking could be why COVID is currently sky-rocketing in Germany. There is, effectively, no vaccination requirement at most places. People just bring fake ones.
Comment: @user253751 the ongoing pandemic certainly isn't a product of human intelligence.
Comment: What kind of certificate was it?
Comment: @Traveller yes.
Comment: Was this a non US-issued vaccine certificate and ID?
Answer: I am in the USA right now and encounter this issue.
For my work, only an official paper document worked. Those should have been given to you when you were vaccinated.
I am from France, there we got an app that display a qr code and your vaccination status. This worked nicely for bar and restaurant. Until now, all of them accepted my electronic proof.
Comment: I've just been to France. They do scan QR codes but never check IDs, so they have no idea whether you're showing your code or someone else's QR code. So they do more work, but the result is basically the same.
Comment: That's because nobody in a bar or restaurant is likely to be adequately trained to verify such documents, which explains why so many anti-vax people are getting away with just printing up fake ones.  As long as you present something that looks reasonably official, I very much doubt you're going to be denied service.  Most places don't even bother checking.  Since getting my shots, I've only had to show anyone my card exactly once (at a concert).  Employers, on the other hand, may have more competent people around to check things out.  We're not nearly as organized as the EU on that front.
Comment: @DarrelHoffman Keep in mind that someone who doesn't want the COVID vaccine specifically is not necessarily an antivaxxer.
Comment: @DarrelHoffman correct, no one seriously enforces this, hence I wouldn't worry about having the "wrong" document. In King County you don't even have to show ID while showing your vaccine card. So tourists from any country in the world have nothing to fear. Its a pretty annoying inconvenience but you'll get into the venue.


Group Policy 2008 My Documents Folder Redirect

Question: I want to use Group Policy to redirect my users' My Documents folders to their network user folders.  When I choose the GP setting that says "Redirect to the user's home directory", it changes all of my users' folder names to "My Documents" on my server.  According to this article, http://support.microsoft.com/kb/947222, the behavior is by design, but it doesn't seem right.  Has anybody had better luck doing this?
Comment: Your question is... not quite comprehensible, even to a drunk SA.  What are you trying to do?  Tell us that and we'll be better able to help you.
Comment: The behavior above is usually seen when the directory for hosting user directories does not have the right permissions set.
Answer: I agree with HopelessN00b but I recently dealt with this myself so I think I understand. It's caused by the desktop.ini file created by Windows. You can either block the file from being created (maybe using FSRM), empty the file and make it read only or redirect the folder to a subdirectory of the remote user folder (e.g. \server\share$\%username%\Documents).
There may be other options but these are three I evaluated. I went with the last option and redirected other folders to their own subdirectories.
Answer: I set it to redirect to a folder within the user's home folder and it worked fine. Users don't notice it if they're going there via "My Documents" and it's only an extra folder to click on if they go via the home folder directly.


What does it mean to fail a saving throw by 5 or more?

Question: I feel like this should be self-explanatory, but I'm not quite sure how it works. Is it essentially a secondary DC that is 5 less than the initial DC? I can not seem to find an example of it anywhere, so one would be appreciated.
Comment: Welcome! You can take the [tour] as an introduction to the site and check the [help] if you need further guidance. Good luck and happy gaming!
Answer: From a plain English reading, failing by 5 or more means having a saving throw roll that is a number 5 below the normal DC or less (see detailed explanation below). This does nothing in general but certain abilities care about how much you failed your save by. For example, the pseudodragon's sting (emphasis mine):

(..) and the target must succeed on a DC 11 Constitution saving throw or become poisoned for 1 hour. If the saving throw fails by 5 or more, the target falls unconscious for the same duration, or until it takes damage or another creature uses an action to shake it awake.

In this case, if a creature hit by the Sting rolls a Constitution saving throw. Then, after applying all modifiers to the save, if the saving throw value is...

11 or more: nothing else happens
between 7 and 10: the target is poisoned
6 or less: the target is poisoned and falls unconscious

WARNING: This may be all you need to know, the rest is a very detailed explanation.

Why does failing by 5 or more mean having a number 5 below the DC or less?1
In D&D 5e, in the basic rules introduction we have an explanation on what rolling a saving throw entails. First you roll a d20 then add any applicable modifiers. The results are determined as such:

If the total equals or exceeds the target number, the ability check, attack roll, or saving throw is a success. Otherwise, it's a failure.
(...)
The target number for an ability check or a saving throw is called a Difficulty Class (DC)

So for the case of a saving throw, we have a fixed number, called a DC, and the saving throw succeeds if the result of the roll (including modifiers) equals or exceeds the DC.
Failing by a number certain is never defined so we have to resort to a normal English interpretation of what this means. Usually if one says "I failed by 1" it means "If only I had got a result that had a difference of 1 from what I got, I would have succeeded".
In the case of a saving throw, the only result that would satisfy this condition would be a result that was exactly 1 less than the DC. In the example of the sting above, the DC being 11 means that someone that rolled a 10 could say "I failed by 1" or, in other words "If only I had got a result of 1 more than what I got (11) I would have succeeded.
In a similar fashion we can interpret "failing by 2" to mean "having a result of a saving throw that is 2 below the DC" and so on, so that "failing by N" means "having a result that is N below the DC".
"Failing by more than one" usually means "failing by a number that is greater than 1" and so we can also similarly interpreted it as "having a result that is 1 below the DC or less".
So we can conclude that "failing by N or more", in the case of saving throws in D&D 5e should mean "having a saving throw result that is N below the DC or less".
So, in the example of the sting, "failing the result by 5" means "having a result that is 5 below the DC of 11 or less". Since 11-5=6 then this would happen when having a result below 6, as was the case in my example above.

1. Detailed explanation suggested by Yakk
Comment: @yakk Well this is just the plain English reading of what "failing by 5 or more" means. I don't really see this being further supported in the rules. Failing a save by a number is never defined as far as I'm aware. Or did you have something in mind?
Comment: Do you have a citation for your math or interpretation of the rules?  Your answer seems to be an assertion, and the quotes/links just repeat the OP's question.
Comment: Yes, you could cite plain English reading, if that is what you have.  I'm saying you are just asserting a definition, not saying *why* you think that is the right definition, and saying *why* makes your answer better.  As it stands, we either trust you (and upvoters) or not; nothing in your answer actually justifies your position.  I mean "failing by 1 is being 1 off a success.  With saving throws, matching the number is a success; so failing by 1 is rolling 1 under the DC.  Similarly, failing by 5 becomes rolling 5 under the DC."
Comment: In a game where matching the target number was a failure (which  has happened in RPGs), then "failing by 5" wouldn't be "rolling 5 under the DC or higher"; it is the fact that matching the DC is a success that makes this your answer right, as far as I can tell.
Comment: @Yakk Alright I see where you're getting at, I've added a more detailed explanation, how's that?
Answer: Your understanding is correct. There is no keyword or special meaning at work here (and when something isn't defined by the game, standard English is applied to understand it), to fail a DC by 5 or more simply means that you roll a result 5 (or more) below the DC.
Example: The DC is 15. I roll an 10. 15-10 = 5, I have failed by 5 or more.
Another: DC is 15. I roll 11. 15-11 = 4, I have failed, but not by 5 or more.
Note the "roll" in those examples would be to total after adding modifiers, so if I have +3 on the roll, the first example I would have rolled a 7 (7+3=10).


Can I subscribe my app to changes in ArangoDB collection?

Question: In MongoDB, there is a possibility to listen for changes in the collection, which allows creating real-time apps. I wonder if there any similar functionality in ArangoDB?
Answer:  arangochair is a Node.js module that adds changefeed capability to ArangoDB and make it realtime push ready
https://github.com/baslr/arangochair
Tutorial
https://www.arangodb.com/2017/03/arangochair-tool-listening-changes-arangodb/
Answer: ArangoDB currently doesn't offer triggers.
One can use FOXX Queues to repeatively execute queries on the database, which then could add such an event to a triggered collection that the frontend can poll for changes.
Comment: queues might be a good solution. I'll give it a try when I'll get my hands on it. Thanks!
Answer: I'd approach this another way: create a Foxx application to "own" or "wrap" the collection. By that I mean only the Foxx app is allowed to change data in the collection. Externally, you invoke actions on the Foxx app's controller to do all data manipulation.
Then, you can give your Foxx app also the task of doing what you were planning to do on your subscriber side. Do it inline if it's a small task, or decouple it a little by using the lifecycle hooks. If the task should be done asynchronously, use a Foxx queue.


What is the literary term for not keeping a story consistent?

Question: For example, if something is established early on in a story but is contradicted by something else later on, almost as if the detail was forgotten.
Comment: If I'm thinking of a "literary term" (e.g. that a *literary critique* might use), I'd suggest the most obvious answer is "inconsistency". If I'm thinking of the term writers and editors use (i.e. in terms of the *craft* of writing), then the accepted answer "plot hole" is probably more common.
Comment: There's "even Homer nods," but that might be a little obscure.
Answer: The term "plot hole" is an example of that, but more details are required to know if that's what you mean.

In fiction, a plot hole, plothole or plot error is a gap or
  inconsistency in a storyline that goes against the flow of logic
  established by the story's plot.1
Comment: It was not actually, but clicking on that lead me to what I was actually looking for: discontinuity/continuity. Which is more or less the same thing haha! Either way, your answer led me to the actual answer I was looking for so thanks a lot!
Comment: @IanLundberg accepting this answer as "correct" but commenting that it isn't, makes no sense and undermines the integrity of our site. Having said that, I think Nancy's answer is a good one. Perhaps you might consider deleting your comment?
Answer: If a character puts something down on a table in one scene, but picks it up again from a counter in another scene, that's a continuity error.
From Wikipedia:

In fiction, continuity is consistency of the characteristics of people, plot, objects, and places seen by the reader or viewer over some period of time. It is relevant to several media.
Continuity is particularly a concern in the production of film and television due to the difficulty of rectifying an error in continuity after shooting has wrapped up. It also applies to other art forms, including novels, comics, and video games, though usually on a smaller scale. It also applies to fiction used by persons, corporations, and governments in the public eye. …
Most continuity errors are subtle and minor, such as changes in the level of drink in a character's glass or the length of a cigarette, and can be permitted with relative indifference even to the final cut. Others can be more noticeable, such as sudden drastic changes in appearance of a character. Such errors in continuity can ruin the illusion of realism and affect suspension of disbelief. …

The article goes on to list several specific types of continuity errors, such as visual errors, plot errors, Homeric nods, and aging discrepancies. With respect to this question specifically, it seems what you're looking for is a plot error.
Sometimes, continuity errors can be introduced deliberately, such as when a character in a piece of fiction is meant to notice something that's out of place.


How would I create this moving flowy mesh on a transparant mesh?

Question: How would I create this kind of effect in Blender? Some kind of attracting material / cloth?
Comment: This actually looks like a simple 3D texture wrapped on a sphere, then moving through global space?
Answer: Extreme deformation meshes with blender tends to break the geometry of the mesh. Here I take a simple cube with 2 faces deleted and some twist modifiers. You animate by increasing the twist values.

Otherwise you could use a procedural texture on a sphere, you map it to an empty that has an animated position. Use alpha values to cut holes in the sphere mesh. Remember to make the inside traceable in Blender Internal, otherwise Cycles will do this automatically, allowing you to cast shadows inside.

And here is the example blend file I made these images with:


Get Wallet balance from SeedPhrases

Question: does anyone know how to get a Crypto wallet balance wit just SeedPhrase without having to log in to the account.
Answer: Your mnemonic seed phrase is the secret that allows your bitcoin to be spent. You should be EXTREMELY careful with how you treat your seed phrase, as a mistake that exposes your seed phrase could mean that someone robs you of your funds.
In practice, this means you should only input your seed phrase into devices and software that you fully trust are secure. Do not ever input your seed phrase into a website, or share it with another person. Doing so is just asking to get robbed.
Any wallet that you use should show you your balance. Note that this is different than 'logging into an account' - a mnemonic seed phrase is not like your usual username/password. If you treat it as such, it is likely only a matter of time until you lose your funds. Really, you should endeavour to handle your seed phrase as little as possible.
Answer: With bitcoin you do not "log in" to "an account".
If you are keeping a balance on an exchange, that is a normal login process, but nothing to do with your seed phrases.
If you mean the balance on a specific BTC address on the public blockchain, anyone can check that, visible to all, from many open websites, anybody's wallet-client, BTC nodes etc.
Seed phrase (+password) is for setting up a wallet-client, and as already mentioned is risky and should be rarely done. Ideally you only keep your private keys on a hardware wallet, and your software wallet-clients are by default Watch-Only without the HWW.
Thus how you "log in" to check your summarized account-wallet balances depends on your wallet-client.
Comment: But I am looking for a way to find the balance of a wallet without having to input my seedphrase in a wallet.
Comment: How do you mean "wallet" there the first time? The collection of addresses on the blockchain (account-wallet) have no outward connection to each other without a wallet-client that can derive all the key chains and derived wallet-accounts. As I stated, a Watch-Only wallet-client will do what you want - total up those thousands of addresses. The master extended public keys (xpub) may be enough, but that depends on the software wallet-client you use.

Get Wallet balance from SeedPhrases


Why did Esther Knas all the Jews?

Question: Esther 4:16 says לך כנוס את כל היהודים "Go Knas (fine) all the Jews." Why did Esther want Mordechai to go Knas all the Jews?

This question is Purim Torah and is not intended to be taken completely seriously. See the Purim Torah policy.
Comment: Please provide an English explanation of  "knas".
Comment: Someone should add an entry to http://meta.judaism.stackexchange.com/q/581/5323 (cc @DanF)
Comment: @DanF - "[Knas](http://www.morfix.co.il/en/%D7%A7%D7%A0%D7%A1)" means a fine or a penalty in Hebrew. Of course, the spelling is different, as the OP is referencing כנוס, when the _knas_ I am talking about is spelled קנס.
Answer: Achashverosh had sold all the Jews to Haman who was arranging to have them all killed. The Mishna on Kesuvos 40b says "כל מקום שיש קנס אין מכר " "Whenever there is a fine there is no sale." So Esther was trying to fine all the Jews which would invalidate the sale of the Jews to Haman.
The Gemara there explains that this is the opinion of Rebbi Meir. Now that we know that they were going in the opinion of Rebbi Meir we can answer another question. Why did Haman's daughter flip the chamber pot over onto her father?
The Gemara in Chullin 139b says ("המן מן התורה מנין (בראשית ג, יא) המן העץ") that the Etz Hadas (tree of knowledge) is a reference to Haman and Bereishis Rabbah 15:7 says that Rebbi Meir holds the Etz Hadas was wheat (Note that Brachos 40a has a different Girsa). Since this was on Pesach and wheat has the status of Chametz on Pesach, Haman's daughter was fulfilling the Gemara in Pesachim 6a "אמר רב יהודה אמר רב המוצא חמץ בביתו ביום טוב כופה עליו את הכלי" that if you find Chametz on Pesach you have to flip a vessel over it, so Haman's daughter had no choice but to flip the chamber pot over onto her father.
Answer: According to the Midrash (have to locate it) Jews attended Achashverush's party when they shouldn't have. Mordechai, Esther's cousin, discouraged Jews from going, but they didn't listen to him.
Esther was, understandably, angry at that, esp. that she was the queen. So, she decided to fine the Jews as a punishment.

Why did Esther Knas all the Jews?


Does the Degreaser affect the afterburn damage of the Flare Gun?

Question: I know that the Degreaser decreases its afterburn damage by 25%, but what about if I have the Degreaser and the Flare Gun (or the Detonator) in my loadout? Is the Flare Gun's afterburn damage reduced by 25%, or is it as normal?
Comment: Damage is only done in whole numbers so Valve rounded it to 2 per tick while normal afterburn is 3 per tick.
Comment: Forgot to mention this in my last note:  Despite the Degreaser lowering afterburn damage by 25%, due to the numbers involved, it actually ends up being by 33%.  That is, it lowers it from 3 per tick to 2 per tick.
Comment: @Powerlord Why does it say -25% afterburn, then, if its afterburn does 40 damage rather than 60? What does the -25% refer to?
Answer: No.
Each individual weapon's special effect only corresponds to only that weapon, not the entire player loadout. It's just like although the Rocket Jumper has -100% damage penalty, you can still kill other players using Melee or Secondary Weapons (it's one of my favourite loadout - Rocket Jumper, BASE Jumper and Market Gardener).
So yeah, your Flare Gun will still have the same damage and afterburn damage as before.
Comment: For reference, hitting the player with a Flare after setting them on fire with a Degreaser will do any immediate damage (90, 41, 30, or 15 depending on which flare gun) and then start dealing the 3 per half second afterburn.
Comment: @alexqwx Afterburn is based on whatever the last damage source was... so if you Degreaser them after Flare Gun, it drops down to 2 damage per half second.  Incidentally, afterburn from crits is 1 damage higher than normal (4 for most items, 3 for degreaser).
Comment: Ah, so, instead of stacking, the afterburn damaged just gets replaced by the most recent fire-based weapon used (in which case I should always Degrease, then shoot a flare)?
Comment: @Powerlord What about if I first flare them, and **then** use my Degreaser on them? What will be the afterburn after I use my Degreaser (assuming I Degreased them immediately after shooting a flare at them)?


Content gone after editing page

Question: I'm having this issue on a dev environment and a quality environment, all of a sudden.
The issue is that whenever I edit a page, imagine to change a title or add a webpart to the rich text html field, through any internet browser, the whole content of the page disappears. My logs show nothing relevant and this is stealing my sleep hours.
Any idea or can I provide you any informating that may help you help me out?
Thank you so much in advance!
Comment: I would use the good old "?contents=1" on top of your page url and cleanup all the webparts, and then start over. perhaps you have some corrupt webparts
Comment: I have the same issue. Even on pages without any web parts.
Comment: you guys should make reference to the SharePoint version and whether publishing is enabled or not
Answer: Somebody else seems to have encountered a similar problem. Like Tiago Duarte mentioned, I would first check the webparts you're using on the page.
Add "?contents=1" to the end of your page URL, then close the web parts one-by-one.
After you close one, check whether editing works normally. If not, close another and test again.

Content gone after editing page


Siphon/Pump Hybrid For Getting Water From a River

Question: Forgive me if this answer is already up on here, but I couldn't find anything particular to what I am trying to do. I need to lift water approximately 50 feet vertically and 200 feet horizontally from a river to the top of our property. I plan to have one hose for water coming from the river, a pump at the highest point of the loop, a bleeder valve at the pumps outlet, and a return pipe back to where the intake is in the river. It's just to keep a stock tank filled up for garden watering, so flow rate is hardly a concern. A trickle will suffice as it'll just be used to keep the tank topped up. Is this a crazy plan or does it have a shot. This is the pump I hope to use: https://www.northerntool.com/shop/tools/product_200578549_200578549?cm_mmc=Housefile--SHIPPED--1206-_-CONF I realize it only self primes up to 12 feet above water source, but I can use what's in the stock tank to prime when needed.
Comment: atmospheric pressure limits you from "pulling" water up more than about 30ft  vertically (because it's atmospheric pressure pushing the water up).. Rather, you're going to need to put your pump down by the river and "push" the water up.
Answer: Two other solutions come to mind, both don't need switches, batteries or electricity:
Have you checked out a wind powered pumping solution - big enough tank to cover low wind times and let it overflow at others.
See https://growerexperts.com/wind-powered-water-pump-for-pond/
Then what about the water pump based on hydraulics? see
https://www.slideshare.net/Fatin62c/homemade-hydraulic-ram-pump-clemson-university
Comment: pump from below - push the water up, trying to suck that high won't work.
Comment: Wind would be tricky since we have a lot of trees and towers get expensive quick. I love the ram pumps, but I believe they require the water source being higher than the pump, even if the water is ultimately taken to an outlet above the water supply. I might be able to use my pump to get the water into a tank above the ram pump, but then I'd be running power and/or buying solar to install down at the river. It also floods periodically so any infrastructure down there is classified "at-risk" lol.
Comment: the ram pump will survive flooding... you can take a small feed from the river to drive a ram pump which fills one reservoir, then a second ram pump fed from that reservoir to fill the tank... seen it done but not arguing about it...
Comment: If you have the tallest redwoods to obstruct the wind... however those turbines are found in some wooded areas...
Comment: Thank you Mike for the ideas. Unfortunately with the pump right near the water it's not the actual flooding that would be the issue, it's the trees floating by. They rip docks sunk in concrete right out of the ground. Do you have any tips on my proposed design?
Answer: Water cannot be 'sucked' higher than atmospheric pressure would push into
a vacuum; depending on
your altitude, that's maybe 30 feet.   So, regardless of 'priming', it won't
suffice to use a high-located pump.
One easy solution is to dig a pit (sump) next to the water stream, and install a well pump there (where it can pressurize the water
for the uphill movement).
Comment: That makes a world of sense. Thank you!


Estimating rewards for coin flip game, given the bias of the coin but not the outcome of the flip

Question: I perform a series of $N$ coin flips, indexed $i = 1, \ldots, N$. I do not get to see the outcome of the coin flips, but for each one I know the probability of the coin being heads, $p_i(H)$. This changes for each coin flip, $p_i(H) \neq p_j(H)$ for $i \neq j$. Depending on the (hidden) outcome of the coin flip, I win an amount of money given by a random variable $x$ which is sampled from one of two fixed distributions, either $q_H(x)$ or $q_T(x)$, which do not vary with $i$. My task is to determine how much I expect to win if I get heads or tails. So for every $i$, I know the distribution of the coin that was flipped $p_i(H)$, and I know how much I win $x_i$. Can I esimate the expected value of $x$ given the coin was heads or tails, e.g. $E[x \vert T] = \int\limits_x  x \, q_T(x) dx$?
Answer: A naive estimator of $E[X \mid H]$ might be the weighted average $\dfrac{\sum p_i(H) x_i}{\sum p_i(H)}$
and similarly of $E[X \mid T]$ might be  $\dfrac{\sum (1-p_i(H)) x_i}{\sum (1-p_i(H))}$
This has the following properties:

If the $p_i(H)$ are $0$ or $1$ (some of each), it will give you the obvious estimates for the conditional expectations
If all the $p_i(H)$ are all equal (not $0$ nor $1$) it will give the same estimates for the two conditional expectations
The estimate of the unconditional expectation will be the mean of the actual amounts won
If the two conditional expectations are actually equal then the expected difference between the estimates of the conditional expectations will be $0$
The difference between the estimates of two conditional expectations may be biased towards $0$ compared with the actual difference between the two conditional expectations


Prove that the group ring $\mathbb{Z}_2[G]$ is not semisimple where $G$ is the cyclic group of order 2

Question: I want to prove that the group ring $\mathbb{Z}_2[G]$ is not semisimple when $G$ is the cyclic group of order two. I guess the simplest way would be to show that there exists a submodule that is not a direct summand. However I do not know exactly how I should go about showing this.
Answer: The group ring $\mathbb{Z}_2[G]$ has only four elements: $0$, $1$, $x$ and $1+x$. A proper submodule $M$ will have order $2$; if $a+bx\in M$, then so is $x(a+bx) = b+ax$; so if $M=\{0, a+bx\}$, with $a$ and $b$ not both zero, then $b+ax=0$ (so $a=b=0$) or $b+ax=a+bx$ (so $a=b=1$). Thus, the only proper submodule is $\{0,1+x\}$, and it has no complement (since there are no other proper submodules).
Answer: Is $\mathbb{Z}_2$ the field with two elements?  If so, there's a non-split exact sequence
$$ 0 \to \mathbb{Z}_2 \to \mathbb{Z}_2G \to \mathbb{Z}_2 \to 0 $$
where the first map sends 1 to $1+g$ ($G = \langle g \rangle$) and the second is the augmentation map.


Let $\{a_n\}$ be a sequence of positive numbers and $b_{n} = \frac{a_{n}}{(a_{1}+...+a_{n})^{2}}$. Prove $\sum_{n=1}^{\infty}b_{n}$ converges.

Question: Let $\{a_n\}_{n=1}^{\infty}$ be a sequence of positive numbers and let $b_{n} = \frac{a_{n}}{(a_{1}+...+a_{n})^{2}}$ for n $\in\mathbb{N}$. Prove that $\sum_{n=1}^{\infty}b_{n}$ is a convergent series.
I'm stuck on how to start this problem. I've considered the limit comparison test, but it hasn't worked out for me. I know I can assume $\{a_{n}\}$ and $\{b_{n}\}$ are positive, so maybe I need to show $\{b_{n}\}$ has an upper bound and apply the positive series test. Any help is appreciated. Thank you!
Answer: Hint:
With $S_n = a_1+ \ldots + a_n$,
$$\frac{a_n}{S_n^2} \leqslant \frac{S_n - S_{n-1}}{S_nS_{n-1}} = \frac{1}{S_{n-1}}- \frac{1}{S_n}$$
Note that $S_n$ converges either to a finite limit or $+\infty$ and in all cases $1/S_n $ converges to a finite limit.
Comment: Clever approach and definitely makes sense to me. Thank you!


The scope of "free for personal use" in fonts

Question: When dafont.com says a font is "Free for personal use", could it be used for local student run show posters as long as I'm not selling the posters?
Comment: _Personal Use_ refers to not using something in a business or _for profit._ I think you'll be fine as long as you're not planning on selling the poster.
Answer: 'Free for personal use' means that it can't be used for any commercial purpose. This means that you would be OK to use it for posters that were just for your own amusement or for your own wedding invitations, for instance. However, you can't use those fonts for making money. This would include making posters for a profit making event or for designing somebody else's wedding invitations that you are charging them for.
Your specific case is somewhat borderline. If you are charging the organisers of the run for your poster design then NO, you can't use that font. If somebody (even a charity) is making money from the run (i.e. via sponsorship) then the answer is still probably NO.
However, if you're designing the posters for free and there is no money being made (or even if the only beneficiary will be a charity) then the safest course of action is to contact the designer of the font and ask them if they are cool with you using their font for that purpose. They have the right to say you can't use it or they may want a fee to allow this use and/or a credit somewhere on the poster.


I want to start using LaTeX on Ubuntu. Where do I start?

Question: There are many different kind of options that you can do  in order to start using LaTeX on Ubuntu. I would prefer doing that through Eclipse, but if there is a better way of doing it, feel free to write your opinion on why using this instead of something else.
Answer: Eclipse strikes me as an odd choice of an IDE to use for LaTeX, but I guess it should work, since the steps in producing a LaTeX-generated document are quite similar to those involved in producing a computer program.
The first step is obviously to make sure you have Eclipse and LaTeX themselves installed. Then, if you haven't already done so, you should definitely install the TeXlipse plugin or some equivalent, which provides syntax highlighting and autocompletion, among other things. (Without it, Eclipse would be nothing more than a glorified text editor and in that case you'd be better off just using a plain text editor.) The TeXlipse user manual provides a good description, including screenshots, which I would recommend you follow to the letter, as all the enabled features will most likely be useful to you. Once you've got the plugin installed and configured, just open a project and try compiling it to make sure it works and to get a sense of how the process works.
Eclipse is, of course, not the only IDE you can use for LaTeX; there are specialized LaTeX editors available. My favorite happens to be Kile, which also provides syntax highlighting and autocompletion, as well as a LaTeX symbol list and graphical build commands that are designed specifically for the LaTeX toolchain. It is based on KDE, so if you are using the default graphical environment for Ubuntu (Gnome) you may have to install some - okay, a lot of - extra packages to use Kile, and it's your choice whether that's worth it or not.
Comment: +1 For Kile- a very nice program and probably the editor that I would use if I was able to use Linux exclusively.
Comment: I've seen a friend of mine using Kile.. and I will try it as well.. but I want to check using Eclipse first :) Thanks for the detailed answer..
Comment: @Sharpie: The KDE libraries do have versions available for other platforms (well I know of Windows at least), although they can be kind of unstable. You could try your luck installing them and see if they'll let you use Kile on your favorite OS.
Comment: I'm also a big fan of Kile.
Comment: I tried all of the stand alone latex IDEs last year, and eclipse was by far the best. If you already use eclipse there's no learning curve, the outline view lets you skip to different sections quickly, you can preview the pdf in eclipse itself and there are many other benefits. I now use emacs though, but I wouldn't recommend trying to learn how to use it just for latex
Answer: Take the editor you are familiar with. Most of the editors have builtin LaTeX support and install the TeX-Packages you need.
If you want to have them all, do a
sudo apt-get install --install-recommends texlive-full

But please be aware that this downloads about 600 MB of software, which expands to about 1.x GB.
I am using Eclipse with Texlipse. Some of my colleagues are using Geany. Other taking LxX.
The messages is, take the editor you like most.
Comment: Just as a heads up, I just tried this command and it says it the install is 2.8 GB
Answer: The package you want to install the texlive package, or one of the things it depends on. Something like
sudo aptitude install texlive-latex-extra

ought to get you a pretty good starting point.
As for editors, even the basic pre-installed gedit ("Text Editor") should at least offer syntax highlighting.
Answer: I don't run Ubuntu but perhaps these links will help:
https://help.ubuntu.com/community/LaTeX
http://texlipse.sourceforge.net/
Answer: If you're on ubuntu, then nothing like using XEmacs. Combined with the AUCTeX package, and reftex for handling citations. it's a dream to use, and is really the best IDE available. What it lacks is the nice latex support that Kile has, so I wouldn't recommend it if you're also trying to learn latex.
Comment: And why XEmacs over GNU Emacs?  (Though I agree that AUCTeX and reftex are indispensable once you start using them.)
Comment: Can you elaborate what AUCTeX is lacking from Kile? Haven't used Kile ever.
Comment: No particular reason. In fact I've reverted back to GNU Emacs on my ubuntu box while still using XEmacs with my cygwin machine.
Comment: Kile has handy mouse-click tables for math symbols etc. You'd have to know that $\alpha$ is written as \alpha for AUCTeX, but in Kile you can just choose it.
Answer: I would advise NOT using gedit. It has two problems.

It slows down as your document gets long (500+ lines), especially when word wrap is turned on
Any math you do, u start with the dollar sign keyword, something like this $e = mc^{2}$ but when you type the first dollar sign, it slows gedit down to a crawl, especially if you have a bunch of text afterwards. I think it goes through the entire document and recolors everything
Answer: I have found the Ubuntu packages to be out of date, making it difficult acquire various latex libraries.  I would suggest:
http://www.tug.org/texlive/quickinstall.html
Comment: This doesn't really answer the question, which asks about using LaTeX, not acquiring it.
Answer: Texmaker is a nice GUI that is native to the Gnome desktop for Ubuntu.
sudo apt-get install texmaker

Comment: Just installed texmaker on 10.04 (LTS). Alas, the gui is pretty "funky" and like nothing else on my desktop. And syntax highlighting is broken.
Answer: I just use gedit to write LaTeX files. I find that the less time I spend trying to "optimise" my workspace, the more actual work I get done.
Recently though I've switched to LyX. It displays figures, equations, and tables in the document, which cuts down significantly on how many curly braces my eyes have to parse. (I can also collapse such "floats" for even less visual noise.)
Answer: My favorite IDE is texmaker. I used Kile in the past, the KDE Latex Editor, another nice one. You can install it with
apt-get install kile

Comment: The aim of the answer is unclear to me, sorry.


Playing a Firre Eladrin as a PC?

Question: The Firre Eladrin is in the Book of Exalted Deeds, page 169. If someone wanted to make a character of this race, how would it work? Is there any way to reduce the +10 LA to something more realistic?
Comment: Just for clarity, are you looking for ways to *change the stats* of the firre eladrin to justify a lower LA, or are you looking for rules-as-written tricks to reduce it?
Comment: At-will *greater invisibility* and *polymorph* combined with *limitless* bardic music and the ability to cast spells like a Clr12 can do *a lot* of damage to the campaign (although still less than a Wiz18). What about the creature is particularly interesting or attractive? Maybe there's a way to get just those abilities *without* being an 8 HD creature with ECL 18.
Comment: I'm looking for any legitimate (i.e. supported completely by the books) way to be able to play this race, particularly conserving the unlimited bardic musics. I understand I can do it with LA 10. Are there other ways that are legitimate which have a lower LA?
Comment: (I'm trying to figure out what information and recommendations, if any, I should include on this race in the New Bard Handbook: joshuad.net/new-bard-handbook)
Answer: Something with a level adjustment of +10 isn't really supposed to be played.

Sure, you could piece by piece, pick apart some abilities to knock off level adjustments, however, that would take a lot of your DM's time and flipping back and forth between the DMG, Savage Species, and Book of Exalted Deeds. But each level adjustment that is reduced is another ability lost for the celestial.

What it looks like you want is a Half-Celestial Bard.

Use the Template Class for the Half-Fiend (but use
Half-Celestial instead).
Now, four levels of the template class doesn't give you any hit
dice. So, in order to get some hit dice Get a Weapon of Legacy and
take the Legacy Champion prestige class.
You can use that prestige class to get the rest of your template
class, all while gaining hit dice and such.

If that isn't your idea of what you would like, what I suggest is:

Your DM creates a Monster Class for the Firre Eladrin.
Get a Weapon of Legacy.
Take a level of monster class that grants a hit die. Take a level of Legacy Champion prestige class for a level of the monster class that doesn't grant a hit die.
Comment: I suspect that this is a much more RAW-minded answer than requested, but even if not, *Weapons of Legacy* is a terrible book and legacy champion is a terrible class. Not good suggestions, IMO.
Comment: @KRyan I agree it is a terrible book and terrible class. It was a RAW-minded answer. Legacy champion being the only "viable" method for the +8 LA Vampire template class still doesn't make it a good idea either.
Comment: Eh, after some thought, I'd relent; legacy champion remains awful and I despise its abuse, but using it to progress (often equally-awful) monster classes is at least creative use that probably winds up somewhat-reasonable. If you edit your answer, note me in a comment and I'll reverse my vote.

Playing a Firre Eladrin as a PC?


Are you allowed to attack creatures instead of a player?

Question: Are you allowed to attack creatures instead of a player during the combat phase? Because it seems to me it's much more easier to block (because you can actually choose what you attack) than to just throw all your critters at the player and hope the right ones don't get blocked.
Answer: Since this is a basic rules question, a quote from the basic rules:

In your combat phase, you choose which of your creatures will attack, and you
  choose who or what they will attack. Each one can attack your opponent or one of your opponent's planeswalkers, but not any of his or her creatures.

You say it'd be easier to just attack creatures. Sure - and that's kind of the point. If you could just use a bigger creature to kill off a smaller creature, combat wouldn't be nearly so interesting, and the game would lose a lot. You really do have to work out how to manage to attack your opponent and get through without losing too many creatures or leaving yourself vulnerable. It's more work, but it's part of what makes the game interesting and challenging, and gives you an edge if you're better at it than your opponent.
Comment: @GerbenJacobs Perhaps I stated it too simply, then. Magic was designed around this idea, so removing it would definitely make the game less interesting. A different game designed around the idea of being able to attack creatures will have made some different design choices.
Comment: @GerbenJacobs, Hearthstone is not Magic. Comparing the two in this manner is like asking why your submarine can't attack my cruiser in battleship, because your bishop can attack my knight in chess.
Comment: Consider that Hearthstone is designed to be a fast-paced game where there is no player interaction (in Magic parlance, passing of priority) during each player's turn. Magic is designed to have a lot of player interaction: its choices with respect to combat rules, instants, and the stack reflect this design philosophy.
Comment: In the (computer)game Hearthstone you can attack creatures and there's a different strategy, I wouldn't call it less interesting. Sorry for not reading the rules!
Comment: Yep, I understand. In MGT it's asking do I attack yes or no, where with HS it's more who and when do I attack.
Answer: No, you cannot. You can only attack a player, or a planeswalker he or she controls.

508.1. First, the active player declares attackers. This turn-based action doesn't use the stack. To declare attackers, the active player follows the steps below, in order. If at any point during the declaration of attackers, the active player is unable to comply with any of the steps listed below, the declaration is illegal; the game returns to the moment before the declaration (see rule 717, "Handling Illegal Actions").

508.1a The active player chooses which creatures that he or she controls, if any, will attack. The chosen creatures must be untapped, and each one must either have haste or have been controlled by the active player continuously since the turn began.
508.1b If the defending player controls any planeswalkers, or the game allows the active player to attack multiple other players, the active player announces which player or planeswalker each of the chosen creatures is attacking.


How do I access ten years of craigslist archives?

Question: I have a craigslist archive from which I am trying to extract details and prices about products. I want to extend my search back to the year 2005, but the tenth page tells me "There is nothing here." The ninth page is from April 3 of 2015, so relatively recent. How can I access craigslist listings from further back than 2015?
Answer: You can see what days the Wayback Machine has archived a given URL by changing the date portion of the URL to an asterisk:

https://web.archive.org/web/*/http://www.craigslist.com/fur/index1000.html

The problem is that they've only ever crawled that specific URL once, and it returned a redirect (status 302).
It's possible that there's some other service out there trying to specifically archive Craigslist entries -- Archive.org just takes snapshots every so often, and is much more likely to miss things that were posted in periods when they weren't grabbing snapshots of the site.


What is the meaning of the Carriage Return symbol in MSO Word?

Question: What is the explanation (meaning) for the Carriage Return symbol shape in Microsoft Office Word?
Answer: The symbols have different meanings:

↲ - is used to indicate a line break where the paragraph does not end. This can be useful for formatting and presentation, especially as the formatting between paragraphs can be different. (not quite the same symbol as Word uses, apologies)
¶ - called a Pilcrow, and originates from the middle ages. It indicates the end of a paragraph. As you can see from my screenshot below, Word (and many other things including web pages) have the concept of "paragraphs", allowing for formatting to be different between paragraphs (i.e: the additional space below), and for the first line of a paragraph to be indented, etc...

In HTML the above could be given as follows:

  Paragraph 1, Sentence 1.

  Paragraph 1, Sentence 2.

  Paragraph 2, Sentence 1.
  Paragraph 2, Sentence 2.

  &tab;Indented by a tab.

Comment: Based on my knowledge, "↲"  is also the Paragraph mark when you choose East Asian languages as Office display language, such as Chinese.
Comment: Oh interesting... do you know what they use in place of the Pilcrow in that situation? I wonder if there are other things I don't know about (like the concept of "_Paragraph_" being unsuitable perhaps?)... Would you be willing to share a screenshot that follows the format I've presented? (It would be good to include in my answer as a variation - or feel free to edit my answer)
Answer: Carriage return is used as EOL (end of line) symbol, see https://en.wikipedia.org/wiki/C0_and_C1_control_codes . Its english name is 'pilcrow' in typography it is alinea. Its origin and meaning are listed in https://en.wikipedia.org/wiki/Pilcrow#Origin_and_name


Background tasks on App Engine

Question: How can I run background tasks on App Engine?
Comment: You should probably remove the php tag, since php doesn't work on GAE.
Answer: You may use the Task Queue Python API.
Answer: GAE is very useful tool to build scalable web applications. Few of the limitations pointed out by many are no support for background tasks, lack of periodic tasks and strict limit on how much time each HTTP request takes, if a request exceeds that time limit the operation is terminated, which makes running time consuming tasks impossible.
How to run background task ?
In GAE the code is executed only when there is a HTTP request. There is a strict time limit (i think 10secs) on how long the code can take. So if there are no requests then code is not executed. One of the suggested work around was use an external box to send requests continuously, so kind of creating a background task. But for this we need an external box and now we dependent on one more element. The other alternative was sending 302 redirect response so that client re-sends the request, this also makes us dependent on external element which is client. What if that external box is GAE itself ? Everyone who has used functional language which does not support looping construct in the language is aware of the alternative ie recursion is the replacement to loop. So what if we complete part of the computation and do a HTTP GET on the same url with very short time out say 1 second ? This creates a loop(recursion) on php code running on apache.

<?php
$i = 0;
if(isset($_REQUEST["i"])){
        $i= $_REQUEST["i"];
    sleep(1);
}
$ch = curl_init("http://localhost".$_SERVER["PHP_SELF"]."?i=".($i+1));
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_TIMEOUT, 1);
curl_exec($ch);
print "hello world\n";
?>

Some how this does not work on GAE. So what if we do HTTP GET on some other url say url2 which does HTTP GET on the first url ? This seem to work in GAE. Code for this looks like this.

class FirstUrl(webapp.RequestHandler):
    def get(self):
        self.response.out.write("ok")
        time.sleep(2)
        urlfetch.fetch("http://"+self.request.headers["HOST"]+'/url2')

class SecondUrl(webapp.RequestHandler):
    def get(self):
        self.response.out.write("ok")
        time.sleep(2)
        urlfetch.fetch("http://"+self.request.headers["HOST"]+'/url1')

application = webapp.WSGIApplication([('/url1', FirstUrl), ('/url2', SecondUrl)])
def main():
    run_wsgi_app(application)
if __name__ == "__main__":
    main()

Since we found out a way to run background task, lets build abstractions for periodic task (timer) and a looping construct which spans across many HTTP requests (foreach).
Timer
Now building timer is straight forward. Basic idea is to have list of timers and the interval at which each should be called. Once we reach that interval call the callback function. We will use memcache to maintain the timer list. To find out when to call callback, we will store a key in memcache with interval as expiration time. We periodically (say 5secs) check if that key is present, if not present then call the callback and again set that key with interval.

def timer(func, interval):
    timerlist = memcache.get('timer')
    if(None == timerlist):
        timerlist = []
    timerlist.append({'func':func, 'interval':interval})
    memcache.set('timer-'+func, '1', interval)
    memcache.set('timer', timerlist)

def checktimers():
    timerlist = memcache.get('timer')
    if(None == timerlist):
        return False
    for current in timerlist:
        if(None == memcache.get('timer-'+current['func'])):
            #reset interval
            memcache.set('timer-'+current['func'], '1', current['interval'])
            #invoke callback function
            try:
                eval(current['func']+'()')
            except:
                pass
            return True
    return False

Foreach
This is needed when we want to do long taking computation say doing some operation on 1000 database rows or fetch 1000 urls etc. Basic idea is to maintain list of callbacks and arguments in memcache and each time invoke callback with the argument.

def foreach(func, args):
    looplist = memcache.get('foreach')
    if(None == looplist):
        looplist = []
    looplist.append({'func':func, 'args':args})
    memcache.set('foreach', looplist)

def checkloops():
    looplist = memcache.get('foreach')
    if(None == looplist):
        return False
    if((len(looplist) > 0) and (len(looplist[0]['args']) > 0)):
        arg = looplist[0]['args'].pop(0)
        func = looplist[0]['func']
        if(len(looplist[0]['args']) == 0):
            looplist.pop(0)
        if((len(looplist) > 0) and (len(looplist[0]['args']) > 0)):
            memcache.set('foreach', looplist)
        else:
            memcache.delete('foreach')
        try:
            eval(func+'('+repr(arg)+')')
        except:
            pass
        return True
    else:
        return False

# instead of
# foreach index in range(0, 1000):
#   someoperaton(index)
# we will say
# foreach('someoperaton', range(0, 1000))

Now building a program which fetches list of urls every one hour is straight forward. Here is the code.

def getone(url):
    try:
        result = urlfetch.fetch(url)
        if(result.status_code == 200):
            memcache.set(url, '1', 60*60)
            #process result.content
    except :
        pass

def getallurl():
    #list of urls to be fetched
    urllist = ['http://www.google.com/', 'http://www.cnn.com/', 'http://www.yahoo.com', 'http://news.google.com']
    fetchlist = []
    for url in urllist:
        if (memcache.get(url) is None):
            fetchlist.append(url)
    #this is equivalent to
    #for url in fetchlist: getone(url)
    if(len(fetchlist) > 0):
        foreach('getone', fetchlist)

#register the timer callback
timer('getallurl', 3*60)

complete code is here http://groups.google.com/group/httpmr-discuss/t/1648611a54c01aa
I have been running this code on appengine for few days without much problem.
Warning: We make heavy use of urlfetch. The limit on no of urlfetch per day is 160000. So be careful not to reach that limit.
Comment: Use the new Task API or the Cron API.  do not use the ones above.
Comment: Correct me if I am wrong, isn't there an AppEngine policy about inter-communication between hosted apps?
Comment: I don't see how it can possibly work. Won't you exceed 10 second quota on 6th recursive fetch?
Answer: You can find more about cron jobs in Python App Engine here.
Answer: Up and coming version of runtime will have some kind of periodic execution engine a'la cron. See this message on AppEngine group.

So, all the SDK pieces appear to work, but my testing indicates this isn't running on the production servers yet-- I set up an "every 1 minutes" cron that logs when it runs, and it hasn't been called yet

Hard to say when this will be available, though...
Answer: Using the Deferred Python Library is the easiest way of doing background task on Appengine using Python which is built on top of TaskQueue API.
<code>from google.appengine.ext import deferred

def do_something_expensive(a, b, c=None):
    logging.info("Doing something expensive!")
    # Do your work here

# Somewhere else
deferred.defer(do_something_expensive, "Hello, world!", 42, c=True)
</code>
Comment: There are pros and cons for using the deferred library, see "When to use ext.deferred" section in Nick Johnson's article: https://cloud.google.com/appengine/articles/deferred?hl=en
Answer: If you want to run background periodic tasks, see this question (AppEngine cron)
If your tasks are not periodic, see Task Queue Python API or Task Queue Java API
Answer: There is a cron facility built into app engine.
Please refer to:
https://developers.google.com/appengine/docs/python/config/cron?hl=en
Answer: Use the Task Queue - http://code.google.com/appengine/docs/java/taskqueue/overview.html
Comment: -1; this is essentially the same answer posted and accepted 2 years ago, with a link to the Java docs instead of the Python docs, when the OP was using Python. Seriously?

Background tasks on App Engine


Who sits next to Senate party leaders when they speak?

Question:

They seem not to be Senators. Who are they?
Comment: "They seem not to be senators" based on what, exactly?
Comment: Funnily, most Senators (including Schumer) did not respond to a PBS question as to the identity of the aide sitting behind them in speeches. https://www.pbs.org/newshour/politics/whos-behind-the-senator
Comment: I'm VTCing this question as the prototypical "too broad" question. The answer below is half-good, half-bad as alas is typical of such questions.
Answer: They are not Senators but rather Senate-elected officers.
The person in the 1st picture seems to be the Secretary of the Senate, Julie E. Adams.

While the person in the 2nd picture is the Secretary for the Majority, Laura Dove.

Photos from http://www.senate.gov/senators/leadership.htm.
Comment: The person int he 1st picture does not seem to be the Secretary of the Senate. I think the person is probably a staff member of the Schumer team.
Comment: Here is a clearer screenshot from today's Russian diplomat meeting speech http://i.imgur.com/BxO8vRn.png
Comment: I'm also pretty sure it's not Adams sitting behind Schumer. You can see a better photo of Adams in https://ussenateyouth.org/leaders-behind-the-scenes-senate-secretary-julie-adams/
Answer: The woman to the right of Schumer is his deputy chief of staff, Erin Sager Vaughn
Comment: Welcome to Politics.SE! Could you add a link to a source where we can see Ms Vaughn for comparison?


How to correct styling of isotope page display in IE?

Question: I'm working on a simple website using Twitter's Bootstrap css framework for the basic styling (don't know if this is relevant info).
I've made a simple filterable products page using isotope.js, which is working as expected in Chrome, Safari and Firefox on my Mac. However, something weird is happening in IE8 and IE9; the images get all scrunched up (they should be square, using WP featured image function), see image.
The URL of the site is: http://www.nieuwkerkonline.nl/het-bedrijf/producten/
Does anyone know what is causing this, and how I may be able to resolve it? The fact that the rounded corners and other CSS3 goodness get left out, I can live with, but the pictures defninitely need to display properly.
Any help would be greatly appreciated.
Answer: try adding
float:left;
overflow:hidden;

to your css classes .post  and .entry-content


Oracle DB upgrade issue - view, audits/logs that hold info

Question: Is there a way in Oracle DB (regardless of version) to retrieve info for a version upgrade, and by means of views or traces/logs?
For example: the timestamp it took place, prior version of the database and current-upgraded version?
Answer: You might be able to look in the DBA_AUDIT tables (if auditing is turned on) to see when the system tables and such were updated during the upgrade. Other than that, I don't know of any place that it would store previous version information and timestamps as to when that changed.
You could take a look at the Oracle binaries on the actual server to see how old they are. This would give you somewhat of a timestamp as to when they were upgraded. It depends on what you're looking to find; last upgrade, date of previous upgrades, etc...


Microsoft Office credential prompts

Question: Microsoft Office applications  prompt for user credentials when associated file types are loaded from SharePoint (xlsx, docx, etc).  Is there any way to pass through the Windows login credentials so users do not have to type their username and passwords into each Microsoft Application?  If not – is there a setting to increase the length of time which the entered credentials are cached so that users do not feel they are constantly retyping their AD credentials?
Answer: The Office application is trying to access the document directly from the server which has to communicate with the server to determine what type of server that's accessing the file and what web authoring protocol is available.
Anytime a new process tries to access the server, the Office application will require renegoiation.
There are different resolutions depending on if users are within the network and if direct editing is needed.
If you are in the intranet, you can configure the server to use Integrated Windows Authentication and then configure the client to enable automatic logon.  The Local Intranet zone has a default configuration of automatic logon with the current user name and password.

Source - http://blogs.technet.com/b/office_integration__sharepoint/archive/2014/02/24/users-are-prompted-for-username-and-password-when-opening-an-office-file-from-a-web-server.aspx
Comment: Thank you - In IE11 I clicked File Properties and saw that the SharePoint site is in the intranet zone.  the Logon setting is set to "Automatic logon only with current user name and password.  The user is internal, using Windows Authentication within SharePoint.   I am not able to recreate this problem - but the user experienced the problem even this morning.  I assume the Logon setting is fine as is.. any other suggestion is appreciated.  I also added, then removed the registry key from the source posted followed by a restart of WebClient each time.  Issue never recreated on my end.

Microsoft Office credential prompts


Enable FIPS on PostgreSQL database

Question: Can someone please specify the steps to enable FIPS on Postgres Database? I have googled but was not able to find anything concrete.
Comment: FIPS = Federal Information Processing Standards?
Comment: You might want to edit your question and explain in a little more detail. See http://stackoverflow.com/faq#howtoask . Define "FIPS"? What exactly do you want to enable, and what do you expect enabling it to do? What gives you the idea there's something called "FIPS" you can enable? Are you used to this from another database? If so, which one? You didn't find anything concrete in Google, ok, what *did* you find? Links? Please follow up, as this question will otherwise get closed.
Comment: yes, Federal Information Processing Standards 140-2, I want that the postgres database should be installed/running in FIPS compliant mode. If it runs in the compliant mode, the data transfer process with use encryption algorithm something like aes-128 etc. The reason why am I looking for this is our product is going FIPS compliant and I want to test whether it can communicate with FIPS compliant database.
Comment: Specifying the target operating system would help clarify the question.
Answer:
Can someone please specify the steps to enable FIPS on Postgres Database?

I don't believe you can run Postgres in "FIPS mode" because of its use of non-approved cryptography. From a past audit, I know it makes extensive use of MD5 (see, for example, Postgres Mailing List: Use of MD5. So lots of stuff is going to break in practice.
Notwithstanding, here are the steps to try and do it via OpenSSL. There are three parts because Postgres is not FIPS-aware, and you need to make some modifications to Postgres.

Step One
You have to build OpenSSL for the configuration. This is a two step process. First you build the FIPS Object Module; and second, you build the FIPS Capable Library.
To build the FIPS Object Module, first you download `openssl-fips-2.n.n.tar.gz. After unpacking, you perform:
./configure
make
sudo make install

After you run the above commands, the fipscanister will be located in /usr/local/ssl/fips-2.0. The FIPS Capable Library will use it to provide the FIPS Validated Cryptography.
Second, you download openssl-1.n.n.tar.gz. After unpacking, you perform:
./configure fips shared <other options>
make all
sudo make install

The critical part is the fips option during configure.
After you run the above commands, you will have a FIPS Capable Library. The library will be located in /usr/local/ssl/lib. Use libcrypto.so and libssl.so as always.
The FIPS Capable Library uses the fipscanister, so you don't need to worry about what's in /usr/local/ssl/fips-2.0. Its just an artifact from building FIPS Object Module (some hand waiving).
Step Two
Find where Postgres calls SSL_library_init:
$ grep -R SSL_library_init *
...
src/backend/libpq/be-secure.c:      SSL_library_init();
src/interfaces/libpq/fe-secure.c:           SSL_library_init();

Open be-secure.c and fe-secure.c, and add a call to FIPS_mode_set.
/* be-secure.c, near line 725 */
static void
initialize_SSL(void)
{
    struct stat buf;

    STACK_OF(X509_NAME) *root_cert_list = NULL;

#if defined(OPENSSL_FIPS)
    int rc;
    rc = FIPS_mode();
    if(rc == 0)
    {
        rc = FIPS_mode_set(1);
        assert(1 == rc);
    }
#endif

    if (!SSL_context)
    {
#if SSLEAY_VERSION_NUMBER >= 0x0907000L
        OPENSSL_config(NULL);
#endif
        SSL_library_init();
        SSL_load_error_strings();
        ...
    }
    ...
}

If the call to FIPS_mode_set succeeds, then you will be using FIPS Validated cryptography. If it fails, you will still be using OpenSSL's cryptography, but it will not be FIPS Validated cryptography.
You will also need to add the following headers to be-secure.c and fe-secure.c:
#include <openssl/opensslconf.h>
#include <openssl/fips.h>

Step Three
The final step is to ensure you are using the FIPS Capable Library from step one. Do that via CFLAGS and LDFLAGS:
cd postgres-9.3.2
export CFLAGS="-I/usr/local/ssl/include"
export LDFLAGS="-L/usr/local/ssl/lib"

./config --with-openssl <other options>
...

Comment: PostgreSQL can definitely be run in FIPS mode on a properly configured RHEL system. See the answer below regarding the STIG by buzz3791.
Comment: @JosephConway - OpenSSL may be providing FIPS validated cryptography, but that does not mean Postrgres is using it. If Postgres is still using MD5, then they certainly are not complying with FIPS 140-2. There's only one MD5 exception I am aware, and that is the PRF function in TLS. The only way to know for certain is to audit Postgres. But I have not done that in several years.
Comment: I am happy to discuss offline sometime, but we have addressed this in the PostgreSQL STIG. If you put OpenSSL in FIPS mode at the OS level per the Red Hat docs (and Ubuntu and SUSE have similar options) then PostgreSQL *does* use it. I have verified this with gdb in a live session. You also have to avoid using MD5 for password hashing, but that is easily done by using an external (LDAP, GSS, Kerberos, etc) or cert auth method in pg_hba.conf (or scram-sha-256 in pg10).
Answer: For PostgreSQL on Red Hat Linux, the https://public.cyber.mil/stigs/downloads/ web site has a Security Technical Implementation Guide for PostgreSQL 9.x which has this check.
Rule Title: PostgreSQL must implement NIST FIPS 140-2 validated
cryptographic modules to protect unclassified information requiring
confidentiality and cryptographic protection, in accordance with the data
owners requirements.
STIG ID:    PGS9-00-008200
Rule ID:    SV-87645r1_rule
Vuln ID:    V-72993

The "Fix Text" reads
Configure OpenSSL to be FIPS compliant.

PostgreSQL uses OpenSSL for cryptographic modules. To configure OpenSSL to
be FIPS 140-2 compliant, see the official RHEL Documentation:

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Security_Guide/sect-Security_Guide-Federal_Standards_And_Regulations-Federal_Information_Processing_Standard.html
For more information on configuring PostgreSQL to use SSL, see supplementary
content APPENDIX-G.

Joseph Conway pointed out "the Appendix G the STIG refers to is in the PostgreSQL STIG supplement, not the [postgresql.org] docs. You can get the supplement (and the rest of the STIG) here: https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_PGS_SQL_9-x_V2R1_STIG.zip
Comment: Actually the Appendix G the STIG refers to is in the PostgreSQL STIG supplement, not the comunity docs. You can get the supplement (and the rest of the STIG) here: http://iasecontent.disa.mil/stigs/zip/U_PostgreSQL_9-x_V1R1_STIG.zip
Comment: For what it's worth, it appears that Ubuntu now supports systemwide FIPS mode as well for OpenSSL. See section 9.1.1 of this doc for how to set it up (untested by me): https://csrc.nist.gov/csrc/media/projects/cryptographic-module-validation-program/documents/security-policies/140sp2888.pdf
Answer: As I understand your question you are looking at trying to ensure that you can encrypt data transferred to and from PostgreSQL using AES algorithms.  While FIPS goes well beyond that, and well beyond what can be asked in Q&A, that question at least is easily answerable.
The simple solution is to use SSL with a certificate authority of your choice (if you are using Active Directory, you could use Certificate Server, and if not you could use OpenSSL to run your own certificate authority).  You could then specify which encryption standards to use (see official docs).  From there encryption will be used and your server will be authenticated to your clients.  You can also set up client certs and require those to be authenticated as well.

Enable FIPS on PostgreSQL database


What's the difference between a sheet sander and random orbit sander?

Question: I'm looking for a sander and as I browse through the various offerings I can see that most manufactures offer both a sheet sander and a random orbit sander.  Aside from the shape of the sanding surface, are there any functional differences between the two?  What scenarios does each type excel at?
Comment: One other consideration that the others didn't mention. Square sheets of sandpaper (Sheet sander) are cheaper than the hook/loop pads for orbital sanders. So if you go through a lot of sandpaper you might save some money with a sheet sander, assuming a job where either tool will work.
Answer: In addition to Rob's answer, the motion of both sanders is a bit different.
Sheet sanders tend to move back and forth in a straight line, with small variation side to side.
A random orbit sander has an eccentric cam mechanism that makes the sanding disc move in a circular but not round fashion. I'd best liken it to the old spir-o-graph toy- it's 'orbiting' around the central point, but it's not a simple circle. You get less noticeable scratches this way.
As to the difference in application.. sheet sanders excel at getting into corners and edges, but can cause grooves because the sheet only moves in one direction.
An RO sander is great for wide open spaces, where if you use a successively finer grit, you end up with a nice smooth surface. But it doesn't get into inside corners very well. My RO sander also has holes in the pad, which facilitates sanding dust removal with a shop vac. (I'm not sure if modern sheet sanders have a dust collection port, but none of mine do.)
Comment: My sheet sander has a lever that allows you to set it for either back  and forth sanding, presumably parallel with the grain, or orbital for more aggressive sanding.  As you might expect, the back and forth (oscillating) motion produces a surface ready for finish.  The orbital motion (not to be confused with random orbital)  produces, upon close inspection, many tiny, but visible circular scratches which have to sanded out, either by hand (quite easily) or by setting the sander to oscillate.
Comment: @ASTPace - nice! My sheet sanders are all old enough to be called 'vintage', so I'm a bit out of the loop there.
Comment: Modern sheet sanders (at least mine) does have a dust port. You just mount the paper, and press it down on the tray that came with the sander and it will punch holes in the right places.
Answer: Sheet sanders usually take 1/4 or 1/2 sheet of sandpaper held in place with 2 clamps, though some can also take hook-and-loop paper. As Graphus pointed out, most models today have dust collection. Many models come with a hole punch in order to perforate standard sheets of sandpaper with the appropriate pattern of dust collection holes, but for some you must buy the hole punch separately. Sheet sanders themselves are relatively inexpensive and the paper is also very inexpensive on models which use normal sandpaper, compared to sanders that use hook-and-loop sanding media.
Random orbit sanders typically use round sanding disks held in place with hook-and-loop (velcro), and have holes in the both the sanding media and the sander's pad for dust collection. A random orbit sander costs the same or more than a sheet sander with more or less the same specs, and the sanding discs cost more than normal sandpaper. You have to be somewhat careful when buying media, because there are 2 "standard" but basically incompatible hole patterns, 5-hole and 8-hole. Although 5-hole sanders are not as commonly sold today, you can still find 5-hole sanding discs. Festool has its own proprietary hole patterns, called Jetstream and Multi-Jetstream. Mirka has its own line of Abranet sanding mesh which, as mesh with many small holes already, doesn't require any particular hole pattern and can attach to any hook-and-loop sander.
Dust collection not only reduces the amount of dust in the air and all over the place, but it also allows the sandpaper to work more efficiently by preventing a layer of wood dust from building up between the sanding media and the workpiece. The resulting airflow across the sanding media's surface also helps against excessive heat buildup, which will melt and destroy the plastic hooks (for the hook-and-loop fastening) on the bottom of the sander's pad.
As TXTurner and LeeG pointed out, the two types of sanders also produce different scratch patterns. Sheet sanders can reach into corners which a random orbit sander cannot do with its circular pad.
Sheet sanders use a linear or orbital (circular) motion, and some can be switched between the two. Random orbit sanders use an eccentric circular motion which is intended to create a less visible scratch pattern, but some higher-end models can also be switched into a gear-driven orbital mode for more aggressive sanding.
Comment: I've found that the universal hole patterns don't perform as well for dust collection on my 8-hole ROS.
Comment: Good answer but not sure about this bit *"Sheet sanders ... usually don't have dust collection except in high-end premium models"* This may be different in different markets but in the UK even budget models can (usually?) have dust collection. Some even also provide a two-part perforation accessory to make up your own paper with the necessary hole pattern to allow it.
Comment: @Graphus hey, you're right; they've made some nice improvements since I last looked at them. Thanks for the correction; I've updated my answer.
Answer: Random orbit sanders rotate and oscillate to give scratch pattern that is harder for the eye to discern.  Sheet sanders typically just have some random oscillation.  RO sanders can be more aggressive.
Both sanders can support dust collection (see Festool), but typically sheet sanders do not have provisions for dust collection, and RO sanders almost always do.
The larger sheet sander (1/2 sheet) are great for finishing a large, flat surface.  Sheet sanders also work well for sanding into corners, something you cannot do with a round RO sander.


Is sound a classical mechanic phenomenon or is it a quantum effect?

Question: I am just curious because sound is longitudinal waves, meaning the energy is passed from one particle to another nearby particle and produces a wave that continues on until it reaches our ear as a sound wave or hits our skin as a pressure wave, so is this considered quantum because of atoms and molecules?
Comment: Sound is classical, and so is classical stat mechanics of atoms and molecules.
Comment: By your logic, everything is quantum. Which is not wrong, but also not a very practical point of view.
Comment: Everything can be potentially reduced to quantum mechanics, but most everyday phenomena are emergent effects resulting from averaing over large numbers of quantum particles, and classical physics describes these.
Comment: Raman scattering, Brillouin scattering, infrared absorption spectra, and many other phenomena relating to sound are *not* classical.
Comment: @AnonymousPhysicist: I think sound becomes a transverse wave when it travels in solid
Comment: There are also transverse waves.
Answer: The detailed physics of sound wave transmission through air were mathematically worked out and found to be accurate before the invention of QM. No quantum-mechanical effects need to be taken into account to accomplish this; it is solidly in the domain of classical physics.
Comment: At least in certain temperature, pressure ranges, and density ranges.
Comment: @Shufflepants, of course.
Answer: Well, niels answer is correct of course. Sometimes you can have also sound in QM system, it is called phonons where a mechanical classical vibration is traveling along the atomic lattice of some materials similar to sound inside a medium.
It is also one of this rare cases where you can treat your quantum system classically.
Comment: The quantum-mechanical phonon theory is only useful once you get to the energy scales of the lattice's vibrational modes, isn't it? Only then it makes a difference whether you regard the atoms as classical or quantum harmonic oscillators. What one would typically refer to as "sound" happens on much larger energies.
Answer: Sound is successfully described using continuum mechanics of solids and liquids (that is the theory of elasticity and hydrodynamics). That is, one need not even descend to the level of molecules/atoms, although it is possible and some interesting phenomena appear at this level.
To summarize:
<code>Sound < Continuum mechanics < Molecular theory < Quantum theory
</code>
Quantum sound
As another answer points out, one can speak of quantized sound waves, such as phonons in solids. Even more interesting are such essentially quantum phenomena as zero sound and second sound.


What problem was solved by introducing the dimension of a vector space?

Question: In linear algebra, we care a lot about dimensions. I get why it's useful but not why it's such a big deal. So I wondered what problem was solved historically by introducing a rigorous definition of dimension of a vector space?
Comment: What makes you think that the definition had to be a response to a problem that needed to be solved? And what makes you think that it was a definition that was created at a discrete moment in time? It was probably a gradual evolution of styles of definition.
Answer: I will begin by 2 examples where the notion of dimension is essential :

The increasing sequence of subspaces

$$\{0\}\subset\ker(A-\lambda I)\subset\ker(A-\lambda I)^2\subset\ker(A-\lambda I)^3\subset\dots$$
(with ultimate stabilisation at a certain step) and the connection of their dimensions with the so important Jordan decomposition of a matrix $A$ relatively to eigenvalue $\lambda$ (well described in this answer by Bernard here).

the concept of degree of field extensions (see paragraph "examples" here) where for example $\mathbb{Q} (\sqrt {2},\sqrt {3})$ can be considered in two different ways as a vector space of dimension $4$ over $\mathbb{Q}$.

But, on an historical point of view, the concept of dimension finds its roots in the connection with

the concept of rank, which was initially defined as the maximal size of a sub-determinant one could extract from a determinant ,[in modern terms : replace in the previous sentence : "determinant" by "matrices"]. We were far, when this concept has emerged, from "rank = dimension of the range of the corresponding linear mapping". This concept of "rank" has emerged (not with this name) when Rouché has published an article in Journal de l'Ecole Polytechnique (1880) explaining the kind of solutions one could expect from a linear system of $n$ equations with $p$ unknowns and rank $r \le \min(n,p)$ .
[connected to the previous item] the "rank-nullity" theorem. Mathematicians have been accustomed more and more to identify a subspace either as the kernel or the range of a certain linear mapping. This can be traced back to 1884 where Sylvester has defined the "nullity" of a square matrix

Here is a quotation of https://mathshistory.st-andrews.ac.uk/HistTopics/Matrices_and_determinants/ :
Sylvester defined the nullity of $n(A)$ of matrix $A$, to be the largest $i$ such that every minor of $A$ of order $n-i+1$ is zero. He was interested in invariants of matrices, that is properties which are not changed by certain transformations. He proved that
$$\max \{n(A), n(B)\} \le n(AB) \le n(A) + n(B)$$.
Remark : The concept of dimension/rank can be enlarged

"The rank of a mathematical object is defined whenever that object is free. In general, the rank of a free object is the cardinal number of the free generating subset G" as explained in https://mathworld.wolfram.com/Rank.html.
it is also to be connected to the "number of degrees of freedom", a somewhat looser concept that can be much more complicated when you are not in the linear case, with manifolds (generalized surfaces) instead of vector spaces.
it has been discovered in the 1960s in the framework of numerical analysis that there is a notion of low rank approximation expressing that for example a set of points in the $n$-dimensional space is "close to belong to $p$-dimensional subspace", using the concept of "singular value decomposition" (a generalization of eigenvalues/vectors decomposition). These concepts are very fundamental in present-day treatments of the so-called "big-data".
Comment: This answer is very thin on historical facts. This seems like a math answer, not a history answer.
Comment: @Ben Crowell I have attempted to give a broader perspective (in particular more historically grounded) to this answer.
Answer: The idea of dimension was already intuitively understood. For example, the ancient Greeks distinguished between plane and solid geometry. And early modern physicists used the notion of degrees of freedom.
It was Liebniz who called for an algebra that would treat the figure as directly as it treated quantity which he called analysis situs. In fact, it was on the basis of his theorising that a competition was instituted which was won by Hermann Grassmann. In fact, if I recall correctly it was Mobius that encouraged Grassmann to enter it. This was on the basis of his book, The Theory of Linear Extension: A New Theory of Mathematics, and what now is known as linear algebra, and more precisely as the exterior or Grassmann algebra.
In this theory the intuitive understanding of dimension is given a rigorous foundation. This is simply the cardinality of any basis.

So I was wondered what problem was solved historically by introducing a rigorous definition of dimension.

The historical problem was the one posed by Liebniz: to give a rigorous exposition of an algebra that treats extension directly. This is the theory of vectors and tensors. An outcome of this theory was a rigorous definition of dimension which showed that this theory was on the right track.
I believe Grassmann actually credited his father with the crucial notion that helped him theorise about extension synthetically.
Comment: I agree that a good answer to the question should probably mention Grassmann (and, by the way, Riemann's habilitation which talked of dimensions of manifolds way before we had the linear concept), but unfortunately what you write there is unclear to me. What "competition" did Grassmann win?
Comment: @torsten Schoeneberg: I don't recall now. It was referenced in a biography of Grassmann that I read a few months ago. I think it was Mobius that encouraged Grassmann to enter it. As I have already written above, it was a competition to flesh out Liebnizs proposal for an algebra of extension.
Comment: I see; yes, wikipedia mentions that prize too. I would think though that Grassmann's main work, the *Lineale Ausdehnungslehre*, in the two editions published during his lifetime,  should foremostly be mentioned here.
Answer: I'm not convinced there was any specific "problem," but simply that a full formal definition allowed people to use multidimensional notation as a shorthand way of defining and managing large amounts of variables.  Sort of like working out the rules for exponentiation, for example.


word order: to keep an open mind vs keep your mind open

Question: could anybody explain why it's said "to keep your mind open" but "to keep an open mind"? I don't understand the reason why the word "open" comes respectively before and after the noun "mind". Why does the word "open" change position?
Thx
Answer:
Keep your mind open.
Keep an open mind.

The first sentence concerns the mind of a specific person. The speaker is telling that person how to keep their mind: they should keep it open. "Open" in this sentence is an adverb modifying "keep". A similar sentence might be "Keep the door closed."
The second sentence uses the indefinite article "a" to refer to "a mind" in general. The speaker is telling the person what kind of mind to keep: an open mind. "Open" in this sentence is an adjective modifying "mind". A similar sentence might be "Stay behind closed doors."
Answer: Often, when a person disagrees with another, the person who is trying to change the other person's mind might say, "Well, Keep an open mind." (I.e., think about it).
Keep your mind open. This might be said in a more general way.
"I do not know if I will be able to complete this class. The material is hard to understand." To which someone might reply, "Hang in there, study and keep your mind open. You may find that it is not so hard after some time has passed.
I get the sense that the first example is more in relation to a particular subject in a conversation. The latter is more of a general statement. However, I would like to see if anyone disagrees.


Is it possible to program an ESP8266 12F using an Arduino Nano?

Question: I just got my ESP8266, but I am unable to program it. Since it can't be connected to via USB, I was wondering if I can program it using an Arduino or perhaps use it as a shield for an Arduino Nano. I haven't been able to find a good guide online. Any help is greatly appreciated.
Comment: Why can't connect via usb?
Answer: Yes, you can program it with Arduino but its a bit complex that way. You will need a separate Linear Regulator with Adjustable Output to get it hooked up with the Arduino.
 Its way better to have an FTDI adapter to program it.
But if you still want to know, there is a tutorial below,
Upload Bareminimum sketch so that no program is running on the Arduino.
Answer:
Is it possible to program an ESP8266 12F using an Arduino Nano?

Yes, but it is much easier to use a FTDI for USB-to-Serial adaptation. Two buttons are also needed to activate the ESP8266 programming mode.
Cheers!
Comment: Could you suggest a link to a better tutorial? Please feel free to update.
Comment: Actually that tutorial has some fairly serious problems.  It claims the regulator is an "LM1117" but neglects to mention that this part comes in various voltage ratings, and it neglects to mention capacitors required by the regulator data sheet.  The author might have gotten away with it using the part they had on hand, but it is not good guidance.


What is a good text for a tooltip to explain a tour's intensity on a website?

Question: I'm working in a website that will sells tours. Each tour has a physical intensity. We have a slider bar that represents that intensity. It goes from green - yellow - red. The current text that appear when you mouse hover a ? icon says "Green represents a laid back tour, red active and between is a perfect blend of both." How can I improve the above text?
Comment: Can these activity level's be quantified in any way? Heart rate? Not suitable for children under 12? Or qualified … "like a walk in the woods" "like a sprint through a battlefield"?
Answer: Go green for chilled, red for thrilled. In-between is less extreme.
Obviously the intent here is to make it short, snappy and catchy via the two rhymes. That second slightly cheesy almost-but-not-quite rhyme could be endearing in a way.
This makes it more memorable not just in the context of meaning of the slider, but perhaps also after leaving the site.
As always - try it out with some people and see what they think.
Comment: I think the terms depend on the conversational tone that the site has. If its a fun site full of quips and whatnots, then "chilled" and "thrilled" are fun words that fit in. But if the site has a serious, directive tone, then those labels don't fit.  And the tone that you should have depends on your target audience and what you're selling them. -- So whats the tone of your site?
Comment: We are selling tailor-made tours, not packages. We target wealthy people after 30 years old.
Answer: While simplistic; would Activity level or Physical activity level not suffice?
The colors will become self explanatory at that point and the amount of mental processing by the user is minimal. It is certainly mundane in its approach; however my guess would be that the use of the slider would be conveyed both accurately and quickly.


How to kill processes using a network interface

Question: The issue I'm having is that whenever I just remove my USB wifi card, it kernel panics and reboots the system. Is there some way to detect and kill any processes using the wifi card automatically to make some sort of shell script?
Comment: But like Gareth says, an _application_ using the WiFi stick shouldn't cause the _kernel_ to panic. The root cause is probably at the kernel level.
Comment: Can you unmount it before removal without problems? http://unix.stackexchange.com/questions/45820/how-to-umount-a-usb-drive
Comment: If you're running on Linux `netstat -tuapn | grep ` should tell you what processes/PIDs are using the IP address.
Comment: There is no notion of "process using a network interface" (apart from some very low-level network diagnostics programs). There is a layer of isolation between processes and network interfaces; processes talk TCP (mostly) and all information about routing TCP packets through network interfaces keeps inside the kernel.
Comment: @Gilles `service ifplugd status` may respond something like `wlan0: ifplugd process for device wlan0 running as pid 1234` (and one can kill it with `sudo ifplugd -k -i wlan0`). I guess what you say implies that there is no  _generic_ way to detect _all_ processes like ifplugd?
Answer: I suspect that the issue is with your driver rather than any process using it.
You'll need to make sure that nothing is using it and then remove it with modprobe -r. Try bringing down the network interface first.  For example:
# ip link set wlan0 down
# modprobe -r <module>

You can find out the module name using lsusb.


What is the difference between sound and vibration?

Question: As far as I know, the only difference between sound and vibration is that sound propagates but vibration does not. In most cases, they are the same.
Please help clarify these concepts.
Comment: Your brain interprets a vibration of the ear drum which is between approximately $20\, \ rm Hz$ and $20\,\rm kHz$ as a sound.
Comment: How is it that vibration does not propagate?  Can you be more specific with examples?  Sound is in fact vibration.
Answer: We will start by describing what vibration is in general and then go on to describe the human perceptible forms.
Any physical quantity which oscillates in time is a vibration or an oscillation. For example, a disturbance in a lattice of atoms gives rise to an oscillatory displacement from the mean position, which propagates along the dimensions of length. Taking such an example in gas, we talk about a disturbance in pressure. Such a change gives rise to a pressure wave through the gas. If we are looking at a disturbance or oscillation in fields, it gives rise to electromagnetic waves. These are only a few examples. A vibration can be manifested in any of the physical quantities.
Coming to the ones we can perceive, we give these vibrations different names. The perceivable pressure waves in air are sound, the electromagnetic waves that we can see are different colours in visible light. Thus, sound is a smaller part of vibrations that exist around us. Hope this clarifies the confusion.
Answer: Sound is vibration and vibrations can be sound depending on if your ear can detect them or not. The human ear can detect roughly 20Hz to 20kHz with perfect hearing. Vibrations also propagate through the material or item that vibrates so I'd say that the statement that vibrations does not propagate is incorrect. The sound however typically propagate through air, perhaps there's a misconception about maybe vibrations not propagating through the air, because at that point they'd probably be sound?
Comment: Even frequencies beyond human hearing are called sound, for example ultrasound.
Comment: That is absolutely correct @Triatticus
Comment: I think the confusion arises in models of wave in solids in which in individual vibration of atomic sites remains relatively fixed while the bulk movement (i.e. the wave) is seen when the vibration of one site is handed off to neighboring sites via some coupling.  Elementary descriptions might say "the individual vibrating atoms don't move far away form their rest position but the net result of the vibration is that a wave propagates through the material".  The "wave" in some sense is seen to have a life of its own, free and unattached to a location.
Answer: Both are similar concepts.
Sound is the vibration of air particles (compression and expansion) the can reach your ears. But you can have vibration being propagated in liquids and solids as well.
Some sounds are generated in structures, so the vibration of a structure is converted to sound in air — for instance, a loudspeaker.


Stipend vs Fee for Australian PhD

Question: I am thinking to apply for a PhD Programme in Australia. But having a look at the websites of almost all the universities, I got to know that the amount of stipend per year a PhD candidate gets is quite low in comparison to the fee.
Is it with the whole world, or its just the case with Australia?
Comment: Fees are waived in US for doctoral students with teaching assistantships. I don't know if this is true in Australia.
Comment: @Buffy Or any other assistantship or fellowship most often; US PhD programs have a listed tuition cost but no one should ever pay it unless they are independently wealthy.
Comment: More precisely, STEM PhDs should never pay tuition. Other fields, not to mention medical or law school, are different.
Comment: @JonCuster Honestly I'd extend it to all fields for PhD; medical and law school are not PhDs.
Comment: @BryanKrause - For better or worse, many of the liberal arts PhDs get minimal support from their program. Many end up working part time to keep afloat. They may get a tuition break, but often no stipend. Whether that is right or wrong, or why people apply and attend is a different question.
Comment: @Buffy "Tuition" is, I pay "fees" every semester.
Answer: For Australian PhD programs, assuming you get the standard RTP scholrship (which is the standard scholarship 90+% of domestic students get) there are two independent components, the tuition fee offset, which covers all tuition fees which the university states they would charge and a stipend of approximately $30K AUD per annum.
For the RTP scholarship, the stipend lasts 3.5-3.75 years while the offset lasts 4 years. Essentially, you would only potentially have to pay tuition fees if you take longer than 4 years full-time study to submit your thesis.
For most students in my school, time from start to submission takes around 3.75-4 years, so many students have to go without stipend for a few months near the end, but I have not met anyone who was charged for tuition fees.
Answer: According to this University of Sydney page, the Research Training Program scholarship includes a stipend and pays the tuition fees.
Answer: From a European perspective, fees for PhDs are uncommon in most major countries. You either get a stipend or a salary, but generally PhD students do not pay to do their PhD. Keep in mind, however, that the height of stipends and salaries varies widely (e.g. Germany >> Italy, STEM >> humanities and so on).
Comment: I'm not sure I fully agree to this. If you count the UK as part of the "European perspective"; it is true that _paying_ tuition fees is uncommon -- those would be covered by the PhD bursary, which would also pay a monthly stipend for the students' living expenses. During my PhD in France, I was a salaried employee, but actually, I had to pay the tuition fees myself, out-of-pocket. Fortunately, these were only about €400/year, so while it felt like a massive hit on my student finances, it was definitely manageable.
Comment: I agree that it's not quite correct, however, tuition fees in the European, without the Anglosaxen, system are not the same as tuition fees in the latter. Another example from Switzerland: PhD Salary ~ 45K/y, tuition fee for PhD 400/y.

Stipend vs Fee for Australian PhD