Why did King Arthur have such a great influence in Brittany?

Question: King Arthur, according to its literature, was a British leader. However, its influence in Brittany is huge. The Brocéliande, the mythical forest where Merlin was buried, is there, lots of family names in Brittany are originally from King's Arthur stories and etc. Why is that?
Comment: Did the character of Arthur have an influence on Brittany or did Brittany have an influence on the folk tale? Cause and effect aren't necessarily clear...
Comment: You may want to read up about Brittany, find out why it's called that and why they speak Breton etc.
Comment: There's a good video on the early medieval origins of Brittany here (https://www.youtube.com/watch?v=DcAsjVIN528)
Comment: He was supposedly the king of Logre, which included part of France + part of the british islands so...
Answer: This question should probably be in the Myth & Folklore SE but let's answer it anyway.
King Arthur is such a major figure in Brittany because Brittany was largely settled by Britons towards the end of the 4th Century and into the 6th Century.
The reasons for this vary by time period, in the earlier wave sources state that Britons were sent to the Amorican peninsula by the Roman usurper Magnus Maximus to enforce his claim in Gaul under Conan Meriadoc (this of course is presented in later documents and should be taken with a grain of salt), later migration is largely considered to be due to the Anglo & Saxon spread westwards (1).
These migrants took their culture with them, hence the similar place names (compare Kernow/Cornwall to Gernow/Cornouaille in the map below) and the Breton language which is in the Brythonic language family with Welsh and Cornish. The later waves migrated at a time when a famous (mythical) warrior named Arthur was popular in Western Britain and of course, took his stories with them. (2)

Sources
(1) Léon Fleuriot, Les origines de la Bretagne: l'émigration, Paris, Payot, 1980.
(2) Concepts of Arthur, Chapter 2.
Answer: This depends on when you think King Arthur existed. The Bretons moved to France at some time between the fifth and tenth centuries from southern Britain. This is why Britain and Brittany are similar words (identical in French, distinguished only by calling Britain "Great Britain"). They took their language, social structure, folklore, placenames (e.g. there is a Cornwall in Brittany) etc. etc. with them and King Arthur would be part of that, the stories being told in a language that was the same both sides of the Channel, only slowly diverging over time.
They would have identified places with the stories. Depending on dates it is also possible that King Arthur did cross the Channel and that events really did take place in France (as it is now called) but in the same culture and language.
Comment: Sources would improve this answer.


Running Microsoft Office Communication Server 2007 R2 on virtual machine?

Question: Does anyone know if it is officially supported to run Microsoft Office Communication Server 2007 R2 on a virtual machine? (Virtual PC/VMWare/Hyper-V)
Answer: Microsoft released a pretty good white paper on it called Running Microsoft Office Communications Server 2007 R2 in a Virtualized Topology. The gist is some roles you can virtualise no problems, but for those Voice, audio/video, Web conferencing, and application sharing roles you need to stick to physical boxes.
Answer: I'm almost 100% sure it is not supported, and I'm certain it's not recommended. If you look at their "best practices", you'll see they use a ton of servers (10, 15?) for all different roles. Our own implementation is only for 200 users and has 3 servers, one edge server, one cwa and one front server. This was the minimum we had to use for our infrastructure.
I'm sure text would work fine if virtualized, but voice/video would become a problem rather fast I reckon.
Comment: Oh, and VirtualPC is definately out of the question. You REALLY don't want to go down that route.


How much yeast can I reuse from the last fermentation?

Question: I have a yeast on the trub from my 5 gallon batch fermentation. I want to reuse it for my next batches.
Is that ok if I add all of this yeast to my next batch?
Or is there any proportion I should follow?
Answer: No specific proportion. Quite a few people reuse the whole "yeast cake".
There are a few gotchas, though. One of them you kinda mentioned - it's not just yeast in the "cake", but all other stuff you don't want to bring to the next beer, like hot/cold break, grain particles, hop material. Another gotcha is that yeast in the cake is usually tired: it depleted nutrients, and is stressed from presence of alcohol and lack of oxygen.
Personally, after reusing various proportions of yeast cake over the years I discarded the whole idea. I'd rather make a starter from a test tube in my yeast library, and get fresh actively fermenting yeast that I'd pitch. That "actively fermenting yeast for pitch" seems to be an important thing.
Btw, Hieronimus in BLAM describes how monks scoop the yeast krausen from fermenting beers (almost with buckets) and pitch it to a next brewed wort. Obviously, for that you need to have a strong pipeline of brews using the same yeast, which is not always achievable at home, but you get the idea.
Answer: The Mr Malty yeast calculator (need flash installed) has an option to calculate how much yeast cake you should re pitch.  Its a ballpark estimate since one yeast cake isn't the same as the next, buts it at least attempts to quantify how much you should use.
You can also scoop up some of the cake, put it in a glass jar with some water and shake it up, and watch it settle over a few hours or days.  In the first hour, most of the trub will settle down.  Then, like a light dusting of snow, the yeast layer will settle on that.  Maybe there will be some other layers of stratified combinations of yeast and trub, but for the most part the stuff that settles first is mostly coagulated proteins / break material and hops aka trub.  That stuff isn't going to help your next batch, and might even affect the flavor. This glass jar experiment is called yeast washing if you do it with sterile water and a clean environment, can get pretty pure yeast.
Of course there is possibly a greater risk of contamination if you go through steps to transfer yeast cake, wash it, reuse it.  It also is another thing to keep clean and worry about.  In the past I have dumped fresh wort right into the same fermenter on top of a cake (lazy way - also this is almost guaranteed to be overpitching, and get a less than healthy fermentation because the yeast doesn't replicate enough and its stressed out yet because theres so much of it it works so fast it blows up and is done too quickly and has done a sloppy job without cleaning up).  I've also dumped 1/3rd of a yeast cake into a clean fermenter, the idea being that I get most of the top layer of yeast cake, and not the trub at the bottom layer.  The best method for reusing yeast cake that I have found it to add some wort or beer, and slightly roll it around to get just the top layer of yeast off the cake and less compacted.  Sort of a "wash in place" if that makes sense.  Then dump that into my new aerated wort.  I think its a good balance between effort and acceptable results.
When almost all professional breweries repitch, they either get the top krausen during peak fermentation, which is all nice active top of their game yeast, or else after fermentation they can drop the trub out the bottom of their conical fermenter, toss it, and finally after the trub layer is drained out the bottom it starts running clean yeast, they keep that part and use it immediately, or within a week or two.
I used to brew every weekend, and would have yeast cakes to repitch onto most of the time.  Usually up to 3 generations before I'd want to switch strains.  I probably saved a hundred bucks on not buying new yeast every batch, but I was never completely satisfied with my re-pitched brews and think this may have been part of the reason.  If you're as cheap as me, its very tempting to repitch, but I think the best chances of making an award winning beer would be to buy the right amount of fresh liquid yeast and pitch properly.
Answer: What I do to save money is pull 3 to 5 liters of my cooled wort aside to make my starter.  I pitch the yeast in this while my wort cools to its desired temperature, then pitch the whole starter when it is at high krausen, usually the next day or so.  This gives me the best results yeast-wise and saves me money on DME.  Pitching a starter made with new yeast at high-krausen will give you the best results overall.  I think this is called a "viability" starter.  Using a stir-plate will get you there faster but isn't truly necessary if you don't have one.  Until I started using this type of starter all of my beers had a residual sweetness (that I didn't like) that I attribute to under-attenuation.  My last four beers I've done this way and none have any residual sweetness.
Comment: While I think I see where you're coming from, I'm not sure if this answers the question as asked.  It could potentially be helpful to someone that finds this post trying to generally find ways to cut costs in brewing but not necessarily someone looking for advice on reusing yeast from a prior fermentation.  Although it's possible I'm misunderstanding what you're saying.  Are you using yeast from a prior batch?  If so, how/how much?
Comment: I was a bit off topic.


Negative facts and truths

Question: I know Russell and Wittgenstein argued about negative truths. It is easy to prove the existence of some property provided there is considerable empirical evidence for its existence, but what if we are concerned with negative properties? Although we could provide some evidence for absence of a particular properties, we cannot prove the nonexistence. Have they reached any conclusions? What is it in the case of negative truths that makes them true? How does one prove that there does not exist some property?
Comment: Did you check out ["Can one prove a negative existential claim?"](http://philosophy.stackexchange.com/questions/3680/can-one-prove-a-negative-existential-claim), ["What does it mean that a claim is a claim of nonexistence?"](http://philosophy.stackexchange.com/questions/739/what-does-it-mean-that-a-claim-is-a-claim-of-nonexistence) and ["Does a negative claimant have a burden of proof?"](http://philosophy.stackexchange.com/questions/678/does-a-negative-claimant-have-a-burden-of-proof)? (:
Answer: A brief answer - It is possible to prove that something "can't exist", which in turn implies that it doesn't exist.  But trying to prove that something doesn't exist directly is a futile effort.
iphigenie's links will give you more detail than I have time to re-hash at the moment though :)
Answer: As Russell was a mathematician as well as being a logician & philosopher, I'm going to take to tackle this question in the realm of mathematics/logic, rather than of empirical science or in a general theory of knowledge.
As Ryno points out its eminently possible to prove that something cannot exist. Usually it involves a reductio, where one assumes that this object does exist and then derive a contradiction.
Brouwer argued for a constructive philosophy of mathematics where to show something exists one must construct it. It turns out that for this to be consistent with the the standard move above one must generalise classical logic to intuitionistic logic which is essentially the classical one without the law of the excluded middle, in fact Brouwer viewed this law as abstracted from finite experience, and then applied to the infinite without justification. (note that in set theory ZF one is allowed to make finite choices but not infinite ones, that requires an additional axiom - the axiom of choice C - to make the standard set theory  ZFC, this is seen as very useful though still controversial).
This is already useful in calculus, where the intuitive idea of the tangent to a curve being an infinitesimal vector couldn't be made rigorous in-itself, it required the rigorous definition of a limit; however using intuitionistic logic, it turns out one can, in what is now called smooth infinitesimal analysis.
(Notably Deleuze writes in Difference and Repetition, "it is a mistake to tie the value of the symbol dx to the existence of infinitesimals; but it is also a mistake to refuse it any ontological ... value,...in fact, there is a treasure buried within the old so-called barbaric or pre-scientific interpretations of the differential calculus...a great deal of heart and a great deal of truly philosophical naivety is needed in order to take the symbol dx seriously...")
So Russell & Wittgenstein were not arguing over unsubstantial issue. I'd be interested to know who took which side...
Comment: Wittgenstein thought that the world consists of facts, not objects. Russell did not like this as this does not allow proving that, for instance, there is no chair in a room where we cannot find it. Searching the room and not finding the chair, does not prove it is not in the room.

Negative facts and truths


No root account

Question: Okay, here's my problem.  I was being an idiot and installed compiz-core on my Xubuntu 12.10.  So there I was, trying to figure out how to fix my issue, and I did sudo xfwm4 --replace.
Then I was unable to login.  So I logging with guest, delete my old account, without deleting the home folder, of course, and I create a new account "michael2".  Instead of creating a new home folder for it, I instead instructed the program to use my old home folder.  Unfortunately, it completely erased the folder, along with over 150GB worth of downloads and about 200 hours worth of work (I work from home, so, yeah).
And to top it all off, whenever I try to use the sudo command, I get the error

michael2 is not in the sudoers file.  This incident will be reported.

I don't know how to fix this, nor can I login to root (I never set the root password, because I never had the need to login as root to do anything).
Any help will be appreciated.  Is there maybe a way that I can do system restore to restore my previous files and username?  I need answers as soon as possible, because I'm literally losing money by the second (the entire work from home kinda thing).
Answer: To regain root access, you will need to boot in recovery mode. When you reach GRUB, select an entry labeled "(...) Recovery mode".
After some time you should get a screen similar to this one, when you should select "Drop to root shell prompt"

Then you will be in a shell as root, and can add your used to the sudo group again:
usermod -a -G adm <your_username>
usermod -a -G sudo <your_username>

After reboot, you should have again sudo permissions. If that's not the case, repeat the procedure but use visudo to add yourself to the sudoers file.
Answer: You'll need to use the Ubuntu installer in rescue mode to mount your root partition and edit the sudoers file to add your new user account.

No root account


What email to use for corresponding author on publications when institution is not permanent?

Question: What is the best email to use as corresponding author when publishing academic papers as a graduate student, postdoc, pre-tenured faculty or other potentially non-permanent position where your email address may change in the next few years? I know many academic institutions will let you turn your email address into a forwarding address, but in cases where this is not possible and your email address will cease to exist when/if you leave, what is the solution? Using something like a gmail address seems practical but rather unprofessional--or is it?
Comment: Strongly related: [E-mail address to use in publications](https://academia.stackexchange.com/q/2872/19627).
Comment: My university offers mail forwarding from the institutional address to a private one after finishing the thesis. Maybe other universities offer this, too.
Comment: @Ian Some do, some don't.
Comment: @Ian True, but this question is specifically about situations where they don't.
Comment: @Dilworth why Gmail and not any of the other hundreds of email providers available?
Comment: Best is to use Gmail, in my opinion.
Comment: @user4050, because in my opinion Gmail is the best provider in the sense of long term usability (i.e., stability of Google as a firm), development and applications supports (gmail for iOS and Android), and overall popularity.
Answer: It has become quite obvious by now that most researchers are on precarious employment for an extended period of time when starting their career.
As mentioned by Michael and Mark, it is very common to find gmail email addresses in scientific publications. I believe that nobody would find that objectionable.
Tips, anyway:

Do not use email@example.com but a variation on email@example.com.
The issue of perenniality remains: GMail deletes inactive accounts after some time. Check their tools to address this issue: https://support.google.com/accounts/answer/3036546?hl=en
Self-hosted email (i.e. firstname.lastname@example.com) is also subject to cancellation if you don't renew your domain/email host.
If you maintain a web presence, your email will be easily findable in the future.

As a kind of "non-requested bonus", I would advise to register an ORCID and have your paper include it (most publishers will include it by now). The ORCID is a unique permanent researcher ID, see their website. On your profile, you can have a list of all your publications and also of your web page. You can include several URLs, meaning that you can list your current institution homepage, your personal hosted homepage, your google scholar account, etc. The ORCID page will be permanent, easily findable and you can update it.
EDIT: you can also list an email (at your preference) on your ORCID profile.
Comment: I think I've actually just updated my long term career goals /success metrics to include reaching a point where I can use email@example.com professionally without worrying about repercussions.
Comment: @Mehrdad Nuts, I guess I'll never be that successful!
Comment: "If you maintain a web presence" and your name isn't Jim Meyer or Wang Wei...
Comment: I'm a simple man, I see "Party Dinosaur", I +1. :)
Comment: @Dandan: It's taken already :(
Comment: There's a disadvantage of using "firstname.lastname" as part of your email address. Not only does it give collisions for common names, but a change in name is far from uncommon. Many women change their name after marriage (or revert back after a divorce). That's often followed by a change of email address. There are of course other reasons why people may change names.
Comment: @Abigail It's a disadvantage over what? Do you recommend using a random unique identifier as your email? Or are you an advocate of party.dinosaur? If your name changes, you can forward mails to your new address, and you can forward them back after.
Comment: I don't understand why people are so fixated with gmail, there is still internet without google services.
Comment: Thank you! I'm pretty sure all my papers have included my ORCID, but I hadn't given it enough thought to consider the profile. Also firstname.lastname@example.com is fantastic.
Comment: Glad you like the email (not mine, in any case) and glad that you consider it a good idea in the long term :-) You can update the ORCID profile at any point in time. If you allow for it, new papers should arrive auto-magically.
Comment: @darijgrinberg well ideally the web presence mentions research interests, reference to publications, or other elements that help to find you in addition to your first and last name such as your past and present affiliations.
Comment: @PierredeBuyl: Research interests change over time. References to publications are probably the best thing to have...
Comment: @Abigail Indeed, using for example gmail, it is possible to keep using the same address and just forward all mail to it from a new one with a more appropriate name. It can be set up so you can send from several different ones from the same account (I did this myself when I got married and changed my surname).
Answer: Many people I see use gmail by now, however, the majority still uses temporary institute email addresses despite losing it at some point - those who want to reach you will still find you, as long as you stay in academia.
Comment: sorry I entered this comment in the wrong answer, apologies.
Comment: oh good, no problem then @user4050
Answer: One option would be to use a permanent alumni e-mail forwarding address provided by an earlier institution you were associated with, in particular the one you got your degree from.
Eg: MIT, Oxford ...
Comment: In my understanding OP referes to the situation where the *current* affiliation email is likely to expire. My solution is to use a permanent address from an earlier affiliation. (I edited my answer to make this more clear.)
Comment: The question specifically asks about the situation where this is not an option.
Comment: @Simppa Good point... assuming at some time you had the opportunity and bothered to turn a previous email into a forwarding address that still functions (my undergraduate address was originally set up as a forwarding address, but I noticed a few months ago that it's stopped working), this would be a good solution. I suppose it might look a little weird using an email that doesn't match the affiliation listed, but no more so than a gmail address and possibly more professional-looking if you're worried about that.
Comment: Joining an alumni association is usually far from cheap. Few would consider a permanent email forwarding address worth it. Furthermore, it isn't even the same address as one had during employment, so the problem of address change still remains!
Comment: @darijgrinberg: "Joining an alumni association is usually far from cheap." — This I guess varies hugely between institutions.  My alumni email address (from Cambridge) was provided for free, and 12 years later is still working fine with no strings attached.  And "it isn't even the same address as one had during employment" — that's not the point; the point is that *going forward*, once you get it, it's an address you expect to remain valid in the long-term, so is suitable for putting on the record in publications.
Answer: Some professional associations like ACM or IEEE provide email forwarding services or full mail accounts (like IEEE). It's not free as it comes with the subscription costs.
I used one of those emails on my business cards as the likelihood of changing institution was high.
Personally, on papers I use the email of the institution that paid me while writing the paper. If I moved in the meantime, I would hope that anyone who really wanted to contact me is able to google my name.
Comment: Re: "not free": if the service is provided by an organization you're expected to be a member of anyway, it's effectively free. Which is definitely not the same thing as truly free, but it's also not the same as costing, say, $100/year (or whatever) outright. I'm not saying you're wrong, just pointing out that it's important to consider the nuances.
Answer: I don't think Gmail is unprofessional. You could also spend the money to set up your own domain and email address - something like email@example.com - which may seem more professional. By having your own website, you could also update with your publications.
Answer: I'll go against the flow and advocate that using gmail or any third-party email is unprofessional. It is widespread, common, and won't offend anyone, but I believe it is unprofessional nevertheless.
I understand unprofessional as against the regulations and policies, conforming to, for instance, the way the ACM Code of Ethics and Professional Conduct phrases it:

MORE SPECIFIC PROFESSIONAL RESPONSIBILITIES.

2.3 Know and respect existing laws pertaining to professional work.
  ACM members must obey existing local, state,province, national, and international laws unless there is a compelling ethical basis not to do so. Policies and procedures of the organizations in which one participates must also be obeyed. […]

But will also argue that it can go against the natural operation of your institution, and lead you to delicate situations.
I - It can be unlawful, or disapproved.
University's policies (that huge booklet you were asked to read) can be weird, go against the usages in your domain, but they still bind you, as an employee.
Some examples:
Auburn University's Employee
 and Student Email Policy reads

The use of non-Auburn email for sending confidential or sensitive Auburn University information is prohibited.

Regent University Electronic Mail Policy reads

Staff are required to utilize their university provided Email (email@example.com) account for all business or educational related communications to and from all other university representatives (faculty, staff, students), business partners, and educational partners.

University of Southern California says

When using email to conduct official university business, employees must use USC email exclusively.

The Use of Third Party E-mail Systems at UCSF reads

The practice of using a third party email service by UCSF faculty, staff and students is not approved by UCSF

II - You can be held responsible for a loss, but don't have any control
You have no control on the way your professional identity will be managed, and yet might be held responsible if something happens. If your third-party get hacked, you can get into trouble for using that address instead of the one provided by your institution. If your institution gets hacked, dealing with the problem will be the responsibility of the institution, not yours. The fact that your institution might more prone to be hacked than the third-party is irrelevant to that point.
III - You are subject to change of clauses
Remember that you have no control over third-party emails. If the third-party decide overnight to go bankruptcy or to impose a $50.000 to access your email, you're screwed. As an employee, you will always be provided an email.
IV - Your are not a product
From an economic perspective, it's not the job of a third-party to provide you with an address: remember, if it's free, then you're the product. And in that case, you were given, as an employee, an email by your institution, so you don't have to look for a free alternative. And providing "brain time" to a third-party on your employer's time can be frowned upon.
V - You are a public person
From the point of view of the outside world, you represent your institution, and using the email they provided shows that you are a full member of that institution (I know that some statistics can be based on the domain of the email you provided to register).

So what?
About the practical aspect, I recommend to use the email provided, and when / if you leave, to

Ask the institution you left to forward your emails (you don't know for sure that they won't provide this facility if you don't ask),
Inform your contacts that you changed your address (prospective readers trying to reach you can email your co-authors as well),
Update your CV, website, and every professional account you have (including ORCID).

If someone try to contact you using that email and gets an error, a quick search (title of the paper + you name) will give them your email if you have a properly done webpage / professional account.
In the end, I believe that, as this similar question, the answers you'll get will be primarily opinion-based. This one is also strongly related.
Comment: -1. I have many objections to the reasoning given in this answer, but one simple one is that "unprofessional" is defined by the dictionary as "_below or contrary to the standards expected in a particular profession_". Since you yourself acknowledge that use of a third party email service by academics is "widespread, common, and won't offend anyone," I don't see how you can logically argue that it's unprofessional. _Inadvisable_, perhaps (I'd still disagree but at least it would make for an interesting debate), but not unprofessional.
Comment: Yes, some administrators are obsessed with regulations of the sort you describe. My goal as a scholar is to ignore them.
Comment: A lot of universities use microsoft 365 or even gmail based services... so having no control, security arguments are a bit irrelevant. The accountability part is true
Comment: "_To me, not respecting the policies is not professional._" Well, I'm sorry but the dictionary disagrees with you. (It also disagrees with you about the meaning of "unlawful", incidentally.)
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/66235/discussion-on-answer-by-clement-what-email-to-use-for-corresponding-author-on-pu).
Comment: In my answer, I ask 1/ How could breaking the policy of your institution be professional? 2/ How could substituting to the IT service of your institution be professional? 3/ How could being in a situation of losing access to your emails overnight be professional? 4/ How could using a service provided in exchange of your professional data, instead of one provided free of charge, be professional? Overall, there's a world of difference between what researchers do (= the standards), and what they are *allowed* to do (= the policies). To me, not respecting the policies is not professional.
Comment: @DanRomik (but thanks for commenting on your downvote!)
Comment: @S.Diaxo There must be something wrong with the way I phrased this argument. I'm not saying that University are more secured than third-parties (as you pointed out, the actual IT handling the security in the end can very well be the same guy). I'm saying that if there's a breach, you can be held responsible for the loss of information, if you use a third-party service. Thanks for pointing out a possible confusion, I'l try to reformulate
Comment: @DanRomik  Unlawful = there's no law saying "use the email provided by your employer", but I would guess there's a law saying "comply to your contract", and not respecting your contract and its policies is breaking that law. No? 2* The [ACM Code of Ethics and Professional Conduct](http://www.acm.org/about-acm/acm-code-of-ethics-and-professional-conduct#sect2), for instance, states, among the "PROFESSIONAL RESPONSIBILITIES", "2.3 Know and respect existing laws pertaining to professional work." We can always find sources contradicting each other `;-)`
Answer: Another option that I have not seen so far is the use of an email alias. Many academic institutions will allow students and other university community members (including faculty) to obtain an alias that they can use after they leave the institution. These addresses are not email accounts but can be used to "point" to existing email accounts elsewhere. Thus, you can list one address—your alias—and have it point to your active account wherever that might be.
Answer: I'm a member of the (UK based) Institute of Physics and they provide an email forwarding services that any emails sent to email@example.com is forwarded to my yahoo account. If you are re you a member of some similar professional organisation, check that they provide this service.
Answer: Your name is known as it is written on the paper. Everybody can google your name and will find your latest website within seconds. I don't think that a no longer valid email address is an issue.
Comment: This is not the case if you are called John Smith, though.
Comment: @svavil : while I won't defend particularly usr1234567's answer, I still believe that a search with the title of the paper + you name (+ your previous institution) will probably lands you on the right page, if it exists.
Comment: Agreed with @svavil above. Also, in the off chance (not entirely unlikely, given the competitiveness of academic positions these days) that a grad student/postdoc/pre-tenured faculty member ends up someday leaving academia and changing fields completely, they may not bother maintaining their professional website indefinitely in case someone wants to talk about their old papers. Or say they become a florist *and* are named John Smith--their website is unlikely to be identifiable as belonging to the author when you're searching for the right John Smith.
Comment: @Dandan: Once people leave academia, many are no longer interested in their papers. If people would be interested, they would maintain some homepage where they list their publications, maybe LinkedIn.
Comment: @usr1234567 As I commented on another answer, I think (and know of) plenty of people who leave academia would still be excited to know that someone is following up on work they spent years on, even if they no longer bother maintaining a website on it. Many people leave because they can't get permanent positions or find academia too demanding, not because they stop caring about their fields of study. The point of this question is how to maximize a reader's ability to contact you once your status changes, regardless of whether you move to a different institution or field.
Comment: Actually, I strongly agree with this answer, assuming of course the author has a website--which he/she should in any case.
Comment: @svavil I think if you are looking for someone with a common name, I am sure you can add a few keywords to the search term to find a specific person.
Answer: Google is an inappropriate email address to use, regardless of precarity
Please don't use a GMail on your papers, it is inappropriate, as it encourages and legitimizes use of that platform.
You see, Google has been verified to pass the contents' of users' emails on to the US government's intelligence agencies, as part of the PRISM intelligence gathering program. This was one of Edward Snowden's revelations in 2013.
While the wide-spread use Google's email service is a fact of life we must contend with - as an academic, you must hold yourself to a higher standard when authoring paper than as a mere individual user, and at least not-encourage your readers to use/communicate with GMail accounts.
Comment: I can't believe so many academians are so easily sold to gmail...
Comment: @user4050: People used to smoke for the longest time too until it went out of fashion.
Comment: Sorry, but my scientific papers are not a platform to insert political messages. I don't care what kind of political wrong doings Google is responsible for. I use their email irrespective of these.
Comment: @Dilworth: Your use of GMail is a political and public action rather than a private action. Mentioning that on your paper is another political action. The fact that something is the status-quo for you does not make it apolitical.
Comment: I disagree. Conforming to the status-quo without being aware of the political context of something, is practically speaking, being a-political. If I use gmail with no political intentions, it cannot be described as a "political action". Something is political only if it has a political *intention*.


What should I watch after "Dragon Ball Z"?

Question: I'm somewhat new to the Dragon Ball universe. So far, I have watched all of the English Dragon Ball Z Kai episodes (1-98), which cover through the Cell games. Currently, I have picked up where Kai left off with the original DBZ, and now plan to watch DBZ through the end. So, what comes after the Dragon Ball Z series? I have read a little bit about titles "Dragon Ball GT" and "Dragon Ball Super"; which one should I watch first following Dragon Ball Z, in order to follow the right chronology?
Comment: This is likely largely a matter of opinion... viewing orders depend on whether you want to watch them in a "recommended" order or in the order of production. [This site](http://www.kanzenshuu.com/forum/viewtopic.php?f=8&t=22315) has a recommended order that might help.
Comment: @Catija Thanks for the link! I am trying to figure out the order in which the characters progress chronologically. For example, I think I read that Dragon Ball Super was produced after Dragon Ball GT, but that DBZ Super is actually a set of story arcs that occur within the greater DBZ universe before the arcs that occur in DBZ GT.
Answer: First of all, watch the classic Dragon Ball, featuring the kid Son Goku. It's amazing and fun until today. The whole concept of the dragon spheres was there and after that the series turns out on a anime about strong enemies and fights.
If you stopped on Cell at the end of DB Kai you must watch the entire Boo's saga which starts on episode 217 on classic Dragon Ball Z.
After that, you could watch Super or get some spoilers on the Battle of Gods (2013) movie, which is mostly the same story, but shortened.
There's also a 2015 very good movie called Dragon Ball Z: Resurrection 'F' that depends on the previous one.
Answer: Dragon Ball GT and Dragon Ball Super are both sequel of Dragon Ball Z but are not connected. GT was not based on the manga by Akira Toriyama but he considers GT to be an alternate timeline.
There is no order in which to watch between the two. Super has just started and isn't complete, so you could watch all of GT now (which only has 64 episodes).
Answer: In term of timeline, Dragon Ball Super took place 6 months after the battle of Majin Buu. It should be the next show you want to watch. It covers DBZ: Battle of Gods and Resurrection of F. It is at episode 26 (still in Resurrection of F)
Dragon Ball GT was released in 1996 with 64 episodes. While it is a sequel to DBZ, it does not follow the Dragon Ball manga series by Akira Toriyama. The series may cause a distortion.
From Wikipedia:

Unlike the previous two anime series in the Dragon Ball franchise, Dragon Ball GT does not adapt the manga series by Akira Toriyama, but is a sequel show to the Dragon Ball Z anime with an original story using the same characters and universe.

Dragon Ball GT was created by Atsushi Maekawa to be the conclusion of the Dragon Ball Series. This could cause a distortion from the direction where the writer of Dragon Ball Z Takao Koyama wants to take the series. Dragon Ball Super manga is written by Akira Toriyama, the author who wrote the Dragon Ball manga (not DBZ). It takes place right after DBZ ended. For those who like DBZ, it is best to watch DB Super and not DB GT.
Answer: If you finish dbz kai  after gohan defeats cell, you should watch the buu saga which starts on episode 217 of the classic Dragon Ball Z but if you want to watch where dbz kai left off at then you should start on episode 200 of the classic Dragon Ball Z
Answer: Dragon Ball GT is based after DBZ but is an alternate timeline so its not original because that show is non cannon but what you should watch is the movies although some of them are not relevant to the story they are fun to watch and the movies made in 2013-2015 are just arcs from Dragon ball super shortened but are good because they are dubbed but the dubs for super haven't got a release date yet so if you don't mind sub's you can watch super but if u don't like sub's you can pass time by, by watching GT or other anime, I recommend One Piece, Fairy tail, Naruto


Distance to epicenter vs distance to focus

Question: I am not really a "budding seismologist." I am a chemistry/physics teacher teaching an Earth science class (low academic level) in a small-town high school. (My college coursework in earth sciences = 0) I understand the concept of triangulation to determine an earthquake's origin, and I realize there are some subtleties in wave analysis such as pP and sP waves. What I don't understand is how the triangulation determines the epicenter instead  of the focus. Wouldn't the S-P lag times for 3 stations give an intersection point at the focus since that is the actual point of origin for the waves?
Comment: @SabreTooth I don't think that is what is being asked. The person asking already has a basic understanding of how the epicenter is found. I think they are now looking for a more detailed answer than was provided in the question you linked to (yes, I did go and read it).
Comment: Welcome to Earth Science S.E. If you need any additional assistance, please visit [The Help Center](http://earthscience.stackexchange.com/help)
Comment: Voting to leave this question open. If you are voting to close as a duplicate, then please leave a comment to indicate what you think it is a duplicate *of*!!!
Comment: @SimonW I retracted the close vote and removed the comment that comes from it.
Answer: This is a good question, but it really has a simple answer. How can you determine the depth of an object when you are not even calculating it? Triangulation uses circles, 2-D shapes, so when finding the solution to the equations of circles that solve all 3 circles, you only find X and Y. Z isn't even being solved for.
Triangulation is not precise. In practice, we end up using much more than 3 stations and statistical methods to find the precise epicenter (and other methods to find the focus).
Comment: I'm no seismologist, but presumably we're talking here about knowing the range from an event to three different locations. That means that we're not dealing with circles, but with spheres.
Comment: Yes, Simon, a sphere would be more accurate, but in the triangulation method that most people use, its solving just for x and y. The point of the method is to just get a general idea of where the quake is on the surface. You don't even need to calculate the solutions, you can just use a compass and ruler to draw the 3 circles if you want to find the point.
Comment: The intersection of two [intersecting] sphere is a circle or a point [degenerate circle.] If a third sphere intersects this circle, the intersection must be a point or two points. So three spheres centered on stations do not guarantee a unique solution for the focus location.
Answer: The method of drawing circles on a map to find their intersection solves for only one unknown. When the stations are far from the earthquake focus, or the earthquake is shallow, the difference between the distance to the focus and epicenter is ignored. Because many earthquakes are shallow, the three circles often do intersect in a point. When they do not, a possible explanation is that it is because the earthquake is relatively deep (compared to the distance to the epicenter.)
If you want to try to determine both the epicenter and the depth of the earthquake, then you need to collect more observations (more stations) and use mathematics to solve a system having at least two unknowns. You might use linear algebra.  Note that arrival times for stations closer to the earthquake will be affected by the depth of the focus than stations far, so you would want to try to include stations closer to the earthquake. Secondary school physics student might have had enough math to use the Newton-Raphson method method to estimate the depth. They might try to used the initial estimate of the 'epicenter' by the first method, to constrain the equations they try to solve to estimate a depth.
In practice, seismologists collect large amounts of data and have to consider many unknowns - such as distance to focus, but also the variation of seismic velocity through different types of rocks.
If you try the three-station and map approach in your Earth Science classroom, the students may notice that all three circles do not go though a single point typically, but come more or less close to doing so. Perhaps this is a good opportunity to discuss the differences between a model and actual earthquakes and Earth. It might even be possible to discuss how a better model can improve the agreement with observations.
It looks like this USGS page : Determining the Depth of an Earthquake has a somewhat different answer, which may describe how deep earthquakes were 'discovered' historically :)
This presentation at the Berkeley Seismographic Station shows a geometric construction and formula for determining earthquake depth.


Battery icon not updating

Question: The battery icon on the panel only changes when I restart or log-out then log back in. For example, my battery is low at 15%, however, the icon indicates its at 79%, which was the percentage when I first booted into the OS.
Comment: well its not an solution ubuntu does good for me but have an issue with elementary then its an bug!!..
Answer: This is a known bug, and is being tracked and worked on:
https://bugs.launchpad.net/ubuntu/+source/indicator-power/+bug/1315434
Answer: Seems to be as a driver issue. It seems you are using a laptop, and in that case updates drivers should be available for your laptop from the manufacturer's website. Try installing that
Comment: Sorry, I'm a bit of noob. How do I download the drivers? It seems like they're only windows compatible. I have a lenoxo ideapad flex 15.
Answer: Me too had the same issue, Power Indicator didn't update once its booted. Found answer in G+. And it works fine for me. Source here.
Downgrade upower to get it working again.
sudo apt-get install upower=0.9.23-2ubuntu1

After downgrade, Do this to prevent the package being automatically upgraded.
sudo apt-mark hold upower

Battery icon not updating


Installation elementary OS 0.4

Question: I am trying to install elementary 0.4 I already have 0.3.2. I went to the elementary web site, I contributed and asked for download but when I check if it has been downloaded its not there. What am I doing wrong, or is this a problem on their end. Answer for an estreme Newbie
Comment: Are you seeing this popup? http://i.stack.imgur.com/6PHxZ.png What browser/os are you using?
Comment: No I am not seeing any popup, I am using Chromium of elementary OS 0.3.2 Freya (32-bit)
Comment: It's possible an extension you have installed is interfering. Does it work with them disabled (incognito mode does this by default)?
Answer:
Go to http://elementary.io
Click the blue "Purchase/Download elementary OS" button
Click "Download Loki" (not the magnet icon, which starts a magnetized torrent download)

The disk image should download to your normal downloads folder.
From there you can follow the install directions at https://elementary.io/docs/installation

Installation elementary OS 0.4


View with field collection and filters

Question: I want to make a profile for musicians. They should type their skills (reference to taxonomy) and levels (radiobuttons) like flute - beginner, piano - advanced,...
Then I need a view with the profile information and the skills and levels. There should be a possibility to search for the skills and levels.
I tried it with a field collection field in the profile but then there is only one exposed filter for the profile field, a textfield for both the skills and levels.
How can I do this? I am getting mad about it. Is there another way to make this work?
Answer: If you would like to look at an advanced application of someone doing something very similiar to you, have a look at the Recruiter installation profile for Drupal 7. Just download, install and then look at how the views, content types, taxonomy and fields are configured. Instead of musicians and skill it is configured to software developers with skills.
Answer: I'd check this post if anyone is still looking for how to expose properties of a Field Collection. I found it helpful.
How to integrate Field collection module in Views?

View with field collection and filters


Twenty Eleven theme header images manual next previous buttons

Question: I have 3 images in my twenty eleven theme header and they rotate by themseleves I want to add next and forward buttons on left and right of my header image to also rotate them manually when I want to see next header image. please guide
Answer: the header image in the Twenty Twelve theme is a random image on page load.
As it is random ... it's difficult to put next and forward links
  - how can you tell if you started with image 1, 3 or x -
In addition, the header is most likely loaded as a background image so you'd have to do some harder coding to avoid a page reload to change from image 1 to image x
If what you are trying to achieve is to have a slider / featured post panel on the homepage then there are many plugins for this.
Comment: thanks for replying. i got what i needed by nivo slider.


Planning next sprint in Agile environment?

Question: My boss and I had a meeting today and the topic was concerned with downtime for dev or QA. We currently work in an Agile environment. My boss wants to start working on dev for the next cycle while QA is going on for the previous sprint. His concern is that this goes against Agile convention. The compromise would be that the branches of development for the current sprint and future sprint would be kept separate. We agreed that it would behove us to reach out to the community and get feedback on the issue.
Answer: Actually, we're doing this exact thing you mention.
Testing in the same three weeks as development is nefarious for testing time and quality overall, as you seem to have experienced. So, we're testing for two or three weeks after the development sprint has finished.
By delaying testing for a few weeks, you'll be working on a fully delivered sprint contract. This is beneficial in multiple ways:

no useless defects are logged (as would be when the stories are only partly developed)
and the inverse is true: stories might impact each other. Once they're all developed, testing becomes much more interesting in terms of quality control.

Also, have a tester (or analyst) sit next to a developer and walk through the new screens or changes, before the dev sprint is done. It only takes an hour or two but gives the dev an opportunity to fix some easily spotted bugs before the actual testing round begins.
Of course, it might go against the Agile spirit, but just like the V-Model or Waterfall, it is a theory. You need to modify it to make it work in your IT department. If you all feel that the change would improve the general development and testing process, don't hesitate.
Comment: How do you deal with issues found during testing, are they put on the backlog? What if they block testing at all?
Comment: Good remark. At my current client, the development team is committed to a week or two of bugfixing before they start a new sprint. And even if they've started one, higher priority bugs on new features are resolved immediately (before it's moved to production after a business acceptance test, which is the third week after development has delivered the sprint). Also, we've now started testing a bit earlier (during the development phase) due to an improved build-deploy process.


How do I uninstall Visor?

Question: Visor (made by Blacktree) is not a regular application, but it seems to be a plugin for Terminal.app in Mac OS X.  How do I uninstall such things?
Comment: Very nice program by the way.
Answer: I'd try removing the Visor.bundle from ~/Library/Application Support/SIMBL/Plugins.  If that isn't enough (it wasn't for me), also remove from /Library/Application Support/SIMBL/Plugins.
Answer: I also have the same problem (except I use BinaryAge's version of Visor). Deleting the
Visor plugin from ~/Library/Application Support/SIMBL/Plugins removed the Visor tab in the Preferences but I think there is some plist file somewhere that saves preferences. The consequence of that (in my case at least) is that I can't resize the first terminal window that opens because it get re-resized automatically (weird) but if I open new terminal windows and close the first one everything works fine.
Answer: just uninstall SIMBL, automatically delete the visor...
start your terminal, go to preferences
under startup, set window to basic
restart ur terminal, and get the normal back

How do I uninstall Visor?


Why are frontal zones connected to low-pressure systems but not to high-pressure systems?

Question: Frontal zones (e. g. a warm or a cold front) are connected to low-pressure systems. But why do high-pressure systems not have frontal zones?
Answer: Not only are fronts associated with (extratropical) lows, but by in large, fronts are extensions of those lows, as shown by the following hand analysis (from the US Storm Prediction Center):

There's a lot going on in the image, but try to focus on the many black lines, which show pressure: they're kinked around each front (and even the dryline).  This indicates that the pressure is higher on either side of the front.  (for another good example: this set of images from the 1993 Storm of the Century from the National Weather Service).  Now the kinks in these drawings aren't caused by the actual layout of observation in the image, but added by the understanding of the meteorologist performing the analysis.  Generally observation sites are too widely spread out to see the small pressure kinks.  However, they do sometimes show up in high-resolution numerical weather models forecasts, even despite not being in the initial observation data they run from:

(From Hartung as indicated... note that the kinks are up instead of down, but that's actually the same result, still pointing away from the low, showing lower pressure at the center of the kinks.)
Though pressure troughs can be spatially hard to see without extremely dense observation networks, they can be made out instead in temporal plots at single locations.  After all, falling pressure has been noticed as a sign of bad weather as far back as the the dawn of America (I often hear Benjamin Franklin cited, but it appears it goes back further to Otto von Guericke in the 1600s).  For example, this trace of temperature and pressure from a 1911 cold front in Louisville, Kentucky:

(source: Louisville NWS)

So, WHY are fronts low pressure areas?
It goes to its nature in connection to winds.  Consider the images below:

(ETA images courtesy of Iowa State's MTArchive)
The plots are two days apart.  So how do you get the conditions to change from the left image to the right over such a period?  While clouds, storms, and sunlight differences can help drive small contrasts, the only way to get such a large, widespread boundary... is to have winds develop that draw the contrasting temperatures tighter together...

Indeed, this is exactly what forms and sustains a front.  You can look at surface weather maps and almost always see this convergence, or gathering together of winds, at fronts, even if only slight, as indicated in this idealized diagram set:

(Image modified from OKFirst, the education arm of the Oklahoma Mesonet program.  See comments for modifications I made.)
The thing is, there's only a few basic forces that drive wind formation... and in the lower atmosphere, it turns out that the pressure gradient force outweighs the others enough such that, on the large-scale, air always flows from higher pressure towards lower pressure.
So if you put those two ideas together:

To create/strengthen/sustain a front, you need wind converging together
Air at low-levels flows from high pressure to low pressure...

The resulting conclusion is that the location where winds are flowing together... which is the front itself... must be a low pressure area.
(What causes low formation in the first place?
Winds aloft typically coupled with terrain enhancements or other small-scale perturbations.  The strengthening temperature gradients actually feedback to intensify and favorably realign the winds aloft... such that, despite the influx of air into the low pressure (which one might think would "fill in" the low pressure with more air, dimi), the air is actually ventilated from the system, allowing it to deepen to yet lower pressures values and strengthen further... continuing on until finally the upper-level storm system surges ahead of the surface low and/or the frontal boundary occludes, cutting warm air from continuing to flow into the surface low center.)

Can you get divergent winds near a developed front?
Yes... in fact, there's a name for that process, it's called frontolysis. Divergent wind does indeed work to destroy a frontal gradient.  And so rising pressure is found connected to dissipating fronts.  However, rising pressure has a long ways to go before it's actually a high pressure itself!  Long before it would create a bona fide high, the early pressure rises only REDUCE the strength of that local pressure minimum... and during that time the temperature gradient will very quickly begin to blur out and fall below the strength of which we really notice.  At the same time, even in this period of decrease, note that this dissipating "front" would no longer have any of the other typical conditions we expect with fronts (no more rising air motions [UIllinois], which is what in turn creates the unsettled weather, clouds, strong winds, storms, etc).
Why is a front so quick to dissipate?  Well, in large part because it's not a level situation; indeed, some storm energy is continually lost away to friction.  Because of this, a front actually needs continual reinforcement to even maintain its gradient.  Some times the pattern will permit fronts to continue through repeated periods of weakening and intensification as upper troughs pass by.  As a trough comes by and then shifts by on east (in tandem with the primary surface low), the front will start to weaken some... perhaps gradually becoming stationary... only to reignite when the next upper system comes in from the west [stationary fronts aren't, as may often be suggested, a cold front and warm front "at war", but instead rather more like a lull in the "battle", where the cold front has run out of steam, but readied next for the warm air to start surging back north should another trough/low move in to re-fire the convergence].  Often you can see quite a long chain of fronts (troughs) connecting together lows pressure systems across continents... (which work into the shape and positioning to the polar jet stream).  Other times, when the upper systems come less consistently or the upper flow starts to break down/shift into other regions, the front will quickly fade from existence.  So much so that I don't believe you're ever not going to see anything like a true front anywhere near a formative synoptic high pressure... unless maybe a giant meteor or as-of-yet-unseen-in-size nuclear bomb were precisely set loose upon a front.  And then... well I suggest trying to witness the brief time that the high pressure is connected to the frontal boundaries... should probably be the least of your concerns!

Of course an important note is that not all lows have fronts, not nearly.  Only "extratropical" (baroclinic, cold-core) lows have fronts.  Tropical (barotropic, warm-core) lows are symmetrical, and don't generate their energy from horizontal temperature imbalances, but instead when overall warming temperature, typically in the mid-levels, decreases the amount of air in the entire tropospheric column...

Found on the AOML, but originally adapted from Merrill, R. T., (1993): "Tropical Cyclone Structure" - Chapter 2, Global Guide to Tropical Cyclone Forecasting, WMO/TC-No. 560, Report No. TCP-31, World Meteorological Organization; Geneva, Switzerland
And for those of you better versed in the more rigorous science... while looking for material for this answer, I came across an absolutely great resource that may prove helpful to those looking to dig much more at the mathematical formulations of frontogensis/frontolysis, the consequential flow types involved in them, and how they impact forecasting: this awesome guide from NOAA's Warning Decision Training Branch.
Comment: you have my vote on this one. Very detailed.
Comment: (if anyone knows of papers showing high-resolution spatial observations of the kinking in fronts, would be great help to edit into the answer!)
Comment: Emily, not sure if this answer quite meets you where you are dynamically to clearly wrap the point.  The QG Omega/Tendency equations... and especially the terms to versions of the Sutcliffe/Petterssen development equation may help to clear it up further (if you're not there yet, there's a fair chance you yet will be by the time you're through school... UWM's Dr Evans' lecture notes [here](http://derecho.math.uwm.edu/classes/SynII/QGDevel.pdf) look quite good on the topic if you're fairly far in your studies, enough so to handle the heavy dynamics)
Comment: you can delete the low pressure stuff a little bit and just keep the frontolysis and high pressure. Just point to a link for low pressure and fronts.
Comment: I modified the frontal image at [OKFirst](http://okfirst.mesonet.org/train/meteorology/Fronts.html) because I didn't feel it properly identified typical winds along warm and stationary fronts, and didn't show typical directions of such fronts. I don't believe the alternate direction of winds north and south of the stationary and warm front are realistic at all, as they suggest different low pressures are dominating flow. Note that stationary fronts with winds from the west often regularly happen where a cold front has stalled. The light blue arrows indicate cool (rather than warm/cold) air
Comment: @gansub, you really thing so?  I definitely thought it's all a bit long (far too typical for me), but felt like it was sort of fundamental, convincing people that it was observed, before going on to explain why
Answer: The (relatively) easy answer is that the mechanism that low pressure systems generally form are different than the mechanism that high pressure areas form.
This begs the question "How do low pressure systems form?" I'll label the steps of the "Norwegian Cyclone Model" in brief layman-speak.

First you need an area where temperatures change drastically with distance, generally with cold air to the north, and warm air to the south.
Up high in the atmosphere, a small disturbance of winds push the cold air towards the warm air (creating a cold front) and the warm air towards the cold air (creating a warm front).
As the warm air advances, the pressure decreases.

High pressure areas, however, have a different formation process, one the involves converging winds and cooling.
In brief: low pressure systems have fronts because (generally) the creation of low pressure systems require differences in temperature. High pressure areas do not- they need different "ingredients."
Comment: @BaroclinicCplusplus - I am not the downvoter. All I can say is you have answered how low pressure areas are associated with frontal zones but you have barely touched upon high pressure systems and frontal zones.


Why is there a compressor in an air cycle machine?

Question: I'm a curious high school student. Why is there a compressor after the first heat exchanger in an air cycle machine? I've read that compressing the cold air is for the cause of efficiency because compressing hot air uses much more work than cold air, and the effect of this is that the compressed air temperature increases. But if so, why compress at all when the air itself is going to be cooled again in the second heat exchanger?  Why not leave the compressor and place the turbine as it is from the ACM?
Answer: If I understand your question correctly, you don't really understand how the ACM works.
The idea of an ACM is to create 'cool' air. Especially on the ground (imagine landing on your tropical holiday destination), this means that the air must sometimes be made cooler than the outside (ambient) temperature. The second law of thermodynamics (and in this case, the law of common sense) states that you can't just cool your air against the warm ambient air, so you will need to do some special tricks.
In this case, the special trick is compression. You compress the air, which will make it quite hot (increase the temperature) (search for adiabatic compression on the internet). Then, this hot air can of course easily be cooled against ambient air, which happens in the second heat exchanger. In fact, the hotter the air after compression is, the more heat is exchanged in the second heat exchanger. This means the heat exchanger can be made smaller, which is especially useful since air-to-air heat exchangers are inefficient and thus relatively big.
Now, you expand your air again, which will cool it (decrease the temperature). However, since you already cooled it down in the second heat exchanger, it will now be cooler than when it originally encountered the compressor! This makes sense, since you removed energy from the air in the second heat exchanger. So, this way, you can cool the air down further than would have been possible by a heat exchanger (search for reverse Brayton cycle on the internet).
So, this system has two advantages:

It is possible to cool down air beyond ambient temperature, so it functions as 'airco' on the ground or at low altitude.
It is possible to cool hot compressed bleed air with a relatively small, light heat exchanger for pressurizing your cabin while not cooking your passengers medium-rare.
Comment: Very nice answer
Answer: Because there is an expansion stage, the energy of the compressed air can be used to run a second compressor. Doing this allows to cool the precompressed air before it is fed to the second compressor, thus improving overall efficiency.
For the same reason, some turbocharged engines use two turbocharging stages with an intercooler between the compressor stages. It keeps the volume of air low and allows for smaller, more efficient turbochargers.
You could also extract the air at a later stage of the engine compressor, cool it and expand it in a diffusor, but then the engine compressor has to do more work and the cooler needs to be bigger due to the higher temperature and lower density of the compressed air. But somehow you still need to shed the pressure energy in the air, and running it through a turbine is an ideal way to achieve this.
Answer: The ACM has a nozzle in the turbine which compression and rapid expansion of air through the conical holes of the nozzle, and inducer and exducer blades of the turbine wheel pulling and pushing air at high RPM's produces the cold air.  Primary cools down bleed air from engine for perameter required,  then temperature leaving compressor discharge into secondary heat exchanger cooling down air sufficiently for turbine inlet air temperature requirements and turbine discharge temperature.  Example,  testing HONEYWELL ACM for 757, and 767, from primary to compressor inlet is 197 to 207 deg. F.  comp discharge temp is about 285 deg. entering secondary then exiting at 205 deg. F entering turbine inlet and outlet discharging at 25 deg. fer. or less. from turbine scroll.  Also, the RPM is 46K to 51K.  Some smaller ATR ACM's go over 100k.


Can anyone explain this frost phenomenon?

Question: Look at this amazing frost I woke up to in Sooke, BC, Canada. This was so very cool to wake up to.
Comment: Hoarfrosts or freezing frost will both look similar to that.  Similar phenomena but form under slightly different conditions.
Answer: I am going to take a guess and say these are Frost crystals. There are few conditions that need to be present in order for these to develop
1) Light wind
2) Relatively high humidity(some water vapor source perhaps nearby)
3) Depending on your elevation - was this somewhere near a mountain basin ?
As opposed to snow crystals frost crystals form more near the surface
You can read this article  Frost crystal and if the answers are in the affirmative
then you know these are the conditions that caused these crystals to form.


Allow registered users post content or articles - Joomla 3

Question: Im looking to allow users to post information on a page. I understand I can give them author rights but I only want them to be able to edit and post content on the 'Submit' page and not the other pages such as 'Home' and 'Terms'. Is there a plugin or method to do this. Any help is much appreciated, thanks in advance.
Comment: I believe you can do this with Joomla ACL. I'm not very knowledgeable in this area, but something like [ACL Manager](http://extensions.joomla.org/extension/acl-manager) may help you.
Answer: As far as I understand you want to give different access to different different menus. For this,in Joomla, we use ACL (Access Control List) and you don't need to use any plugin or extension. Refer the link below:
https://docs.joomla.org/J3.x:Access_Control_List_Tutorial
You can give different authorities to different users. Please have a look in the following example as well:

Open 'Submit' menu item in Menu Manager > Submit: In the right sidebar, you will find an option Access , set it to Guest. By doing this, you allow only the guest users to view the submit page .

Guest users are those users who are visitors of our website.

For Home and Terms, set the Access option to Registered. By doing this, only the registered users will see these menu items.

IN this way, you can easily restrict different users accessing different menus/pages on your website.
Hope this helps
Answer: No plugin is needed! Your best option is to assign the Home and Terms navigation links to single articles.
You then assign other menu items to display specific categories that you've chosen, which your users will then have the option of selecting from. When they categorize their article, it will display on the appropriate page since that page is set up to list all articles within a category.
Hope this helped!
Edit: I realized I misread your question. You can change editing permissions by assigning editing permissions on a per-category basis on the backend.
Add a link to your user menu that takes users to the article submission form, which ships with Joomla, and make sure that user permissions are set for all of your categories.


Disable second monitor

Question: The problem
I have a 2008 iMac running OS X 10.7 with its mini-DVI output port connected to an second monitor via a DVI-D adapter.
It's nice having a second monitor, but it's sometimes superfluous and I would like to turn it off to conserve power.
Ideally, I would like the iMac to detect when I turn off the second monitor and then stop extending the display onto it. But that's not what happens; I need to unplug the DVI cable before the iMac recognizes it as removed.
Explored solutions
Mirroring the display: The second monitor is in portrait orientation, so mirroring turns the display into rather comically cropped square.
Moving the display arrangement to eliminate common borders: The display is still there, so applications sometimes still open up windows on it.
A hardware solution like a KVM switch or the product described here: I'd rather not.
This question is more in line with what I'm looking for, but they ultimately went in a different direction. Is there a viable solution using XRandR, though?
Finally, if there are no OS X native solutions for disabling a monitor, I suppose I must ask: is there an app for that?
Answer: One possible solution is SwitchResX, however, it costs money, and personally I would prefer an AppleScript or shell command for that purpose.

Disable second monitor


Off-shore bug fixing

Question: If a prospective employer told you they "outsourced bug fixing because developers hate fixing bugs", What would you think? What might be your concerns?
Comment: Developers hate fixing bugs? I think it's more they hate finding a reliable way to _reproduce_ the bug, which is what testers are for. If you're outsourcing bug fixing, you may as well outsource the entire development team. No one understands the code as well as the person who _wrote it themselves_.
Comment: Sounds like a terrible idea.
Comment: @AndresF. +1. This will create an environment where devs just throw crap at the wall and hope it sticks. Ain't their problem if it doesn't, right?
Answer: Fixing our own bugs actually makes us a better developer. And it's a pretty enjoyable moment for me. Especially when they are nicely reported.
If they don't like to fix bugs, the problem lies elsewhere.
I suspect the problem is how bugs are perceived by the management or worse, by bad design decisions and/or no (unit) testing, causing bug fixing painful.
Outsourcing bug fixing will probably make thing worse.
Developers may be tempted to do reduce quality. Who cares? Some offshore guys are there to clean up their mess.
Until the offshore guys replace the onshore guys.
Comment: @Aditya : nothing scary here, this is EXACTLY what is happening at my last employer.  The offshore guys had enough of bug fixing all the time and their manager (amen to him) started to provide training.  At one point they got good enough to start simple refactors, clean ups etc.  In the mean time in the main office nothing changed.  I can very easily see that within the next year the offshore guys will do most of the work and the main office guys ... well...  just too bad they did not see the train coming ;-P
Comment: lol you like to scare the heck out of people dontcha
Answer: Leave, run away... fast and never look back...
I have worked for such a company, they thought they were smart,

hey we've got all them bugs but our seniors complain they spend too much time fixing bugs.
let's open an offshore office and let the others deals with this.

for a manager that sounds like a really good plan and the devs were finally freed to tackle the more interesting task of creating the next best thing!!
ho... but wait...
after two years, they went from a team of 5 devs in their main office who handled it all to a team of 2 that create new stuff and a team of 30 that find and fixes bugs.
you know what... the bug fixing team is struggling, they can't keep up.
this made the  "seniors" completely unnacountable for their own mistakes.  Worst still, because it all happened so far away the management did not realize either and the code quality plumetted VERY fast from an already abysmal quality level.
When I left they already opened two more offices for bug fixers and they still cannot keep up behind the now only dev that create them.  they actually think it's because the new guys are not smart enough...
so yes, from now on, if a company say they outsourced their bug fixing to an overseas office trust me.... i run... fast.
This is the Paper Bag management methodology.
Stand on a railway, wait for a train to come, when you see it, put a paper bag over your head and... POOF.. train gone !!.  Magic !
Answer: Having the company pay someone else to clean up my mess sounds like a good idea except when I'm expected to take their 'clean' code and add new features. And if they get it so screwed up that they can't fix it, you'll be debugging the debugging.
Not being adequately compensated because they have to hire additional developers is not desirable.
Having to spend a disproportionate amount of time educating the other developers when you could have fixed it yourself is counter-productive.
Part of me feels like those who create problems should be the ones to fix them or there is no incentive to avoid creating bugs in the first place.
Answer: Are the developers not interested in learning from their mistakes? Can you fix bugs without specific domain knowledge, and does the outsourcing partner has this knowledge? The fixing part is the easiest most of the times, its the analyse portion that takes the time. From my perspective it is a dumb decision.
Answer:
If a prospective employer told you
  they "outsourced bug fixing because
  developers hate fixing bugs", What
  would you think? What might be your
  concerns?

I would run far, far, far away. A developer is always, always, always responsible to fix his own bugs. Eating one's dog food is a basic tenet of good engineering.
Furthermore, bug fixing is as important, perhaps more so than development. I mean, development is code writing, testing and debugging/fixing.
What I get from this company is that they are treating bug fixing as a second-class task. That on itself is pretty disturbing and I would highly question their work quality (and ergo, their work environment.) More disturbingly is that they delegate what for them is second-class work to workers offshore. That is more disturbing. Clearly there is social stratification enshrined in their engineering process.
A defect is always root-caused to a change, and typically the bug is the responsibility of
whoever introduced the change. Who better than the originator to understand the nature of the bug and its resolution?
If it is delegated across the world, how do make sure the original author is available to the offshored engineer?
Will he even be available, leaving the offshored engineer who has nothing but a backlog of bugs and deadlines, but no support from the Metropole? What type of bug fix could a person possibly hope to perform? Who fixes his bugs? And what prevents the Metropole's developers from learning via bug fixing post-mortem?
There are assholes in all fields. This specially true in software. Since it is inevitable, your only option is to work with assholes that know more than you or are doing things right. This company does not seem to fit that description.
In short, run away.
Comment: "Furthermore, bug fixing is as important, perhaps more so than development." I know what you mean there, but I'd go as far as to say: I can't fathom any such dichotomy. Bug fixing is an intrinsic, fundamental aspect of development.
Comment: @Dan - yep, your statement is far more correct. No such dichotomy exists.
Answer: Do they really expect a bunch of off-shore junior developers to be able to fix up a bunch of senior developers code? Its like having a nurse double check all of the neuroligists work and redoing it where he made mistikes. BAD IDEA!
Answer: I would be concerned how well their employees actually know the code they are developing.
I also would wonder the reason there are enough bugs to justify the added costs that this brings.  I would also worry about long term future of the company, there are many articles on the web that claim these firms, use the same code for multiple projects even in the same industry.
Fixing broke code is part of the process of writting code it allows you to have a better understanding of what you did wrong 6 months ago, so you don't make the same mistake, if some other developer fixes your mistakes how do you prevent that bug from happening again and again?
Answer: This sounds vaguely like my previous employer, except for the "prospective employer" bit. They've been losing developers to attrition and have lost too many to support existing products while adding new features required by changes in laws and regulations (60% of the office's revenues come from a VB6 based product, and MS has stated that the VB6 runtimes will not be distributed in any future operating system, so it will be like when Vista came out - a mad scramble to fix things). The powers-that-be want to bring the company public soon, so they're starving everyone for resources to make the balance sheet look better than it is - so hiring offshore is the only way to even come close to staying in the market.
Based on my experiences, what the quote says is that your prospective employer is cheap.
Comment: +1 for having the worst possible job ever.  It sounds like they didn't use enough of that revenue back into the project.
Comment: except for the "prospective employer" bit < LOL
Comment: I notice the phrase "previous employer".  Congratulations.
Comment: @Ramhound, David, Greg, It was a better place when I started, I left the place at the end of December (shortly after my 5th anniversary). No one had been hired since I was hired, and in the past 2 years, 6 developers have quit. The latest one to depart had been there 11 years.
Answer: It depends what they mean by "fixing bugs". If this is fixing bugs during the dev/test cycle then it is very odd, this is the job for the original developers. If, on the other hand, they mean they have outsourced maintenance of a released product then this is not unusual and not something I'd worry about.
Comment: Good point, no one else has envisaged that angle.
Comment: @Greg & Steve - I don't believe it matters to be honest.  If they are fixing bugs in say a release version how can those fixes ever get merged into the test build if the developers don't write the bug fixes themselfs.
Comment: If the bug fixes are checked in to source control they can easily be meged by another team in to another branch. It's not a big deal at all.
Comment: You make a good point though I'd really approve this scenario only in a case where the application is a legacy system that is no longer being actively developed but needs to be kept functional for some reason.  Say a new generation that is a complete rewrite form the one in question.
Answer: My experience has been that bringing in an external team after the fact will burn about as much time as just fixing your own bugs -- they need to be brought up to speed and brought into the development process. And then kept up to speed continuously. Coordination is harder than writing code.
Answer: If I'm going to work on a codebase, I'd like some assurance that everybody with commit privileges is reasonably competent.  This includes quite a few people in India, say, but not the ones that are usually offshored to.
Moreover, most of my bugs are in more complicated sections of code, and those are the ones the offshore programmer is least likely to understand before applying a bug fix.
Answer: This policy actually exists subconsciously in some companies.  I work for an outsourcer; myself and my colleagues are more proficient programmers than the guys onsite, they ask us to teach them how to use tools etc., but the other side of that is that we will spot problems in their code more quickly than they do.
Generally the client's programmers are physically located in the same building as at least some of the users, so they are more likely to get context that doesn't reach across hemispheres.  We find it works well, the missing part for me is that they are not reviewing our code so when the contract finishes they may have some surprises or questions, not due to any shoddy practices on our part necessarily but just the usual problems you have when taking over someone else's project.
In any case I'm glad that in our case it's not an official policy, as such I think it would erode the onsite programmers to being little more than BAs.

Off-shore bug fixing


Summing $r(r+3)$ using induction

Question: We want to prove the following summation by induction:
$$\sum_{r=1}^{n}r(r+3)=\frac{1}{3}n(n+1)(n+5)$$
The problem is posted for a friend, but others can look at the solution if they want/need.
Answer: Let us denote the sum by $S_{n}$. We first establish the base case, that $S_{1}=1(1+3)=4$ is equal to $\frac{1}{3}\cdot 1\cdot 2\cdot 6=4$, which holds.
Then, assume that for some $k$, that $S_{k}=\frac{1}{3}k(k+1)(k+5)$. Obviously $S_{k+1}=S_{k}+(k+1)(k+4).$ Tidying up, we have
$$S_{k+1}=\frac{1}{3}(k+1)\left[k^{2}+5k+3k+12\right]=\frac{1}{3}(k+1)(k^{2}+8k+12)=\frac{1}{3}(k+1)(k+2)(k+6)$$
Which is as we expected. If $S_{k}$ is given by the formula above, then $S_{k+1}$ is. Therefore, since the claim holds for $n=1$, it holds for all natural $n$. $\square$
Answer: Just an addition to Daniel's answer. There is a slightly different way of proving such values, called perturbation method (see Concrete Mathematics, Chapter 2 by Graham, Knuth and Patashnik).
Clearly the value you want is
$V_n = \sum_{k=1}^{n}k(k+3)=\sum_{k=1}^{n}k^2 + 3 \sum_{k=1}^{n}k=S^{2}_{n}+3 S^{1}_{n}$, here 2 and 1 are superscripts for convenience.
Now look at $S^{2}_n = \sum_{k=1}^{n}k^2$, hence $S^{2}_{n+1}=S^{2}_{n} +(n+1)^2=\sum_{k=1}^{n}(k+1)^2+1=S^{2}_{n}+2 \sum_{k=1}^{n}+n+1$. From this we can easily find by rearranging terms that
$$
S^{1}=\frac{n(n+1)}{2}
$$
This solves the second problem. Now let's look at
$$
S^{3}_{n}=\sum_{k=1}^{n}k^3 \Leftrightarrow S^{3}_{n}+(n+1)^3=\sum_{k=1}^{n}(k+1)^3+1=S^{3}_{n}+3S^{2}_{n}+3S^{1}_{n}+1
$$
Once again, after some algebra we find that
$$
S^{2}_n=\frac{(n+1)^3}{3}-\frac{n(n+1)}{2}- \frac{n+1}{3}
$$
Now we have both results for $V_n$. Plug them in the expression above, do some algebra adn you will get the desired result.
I should say this method is quite universal.

Summing $r(r+3)$ using induction


Running Tezos node with rolling mode but sync started at the beginning

Question: I'm running the node by described here:
https://medium.com/@Jamyye/install-tezos-node-on-ubuntu-18-04-rolling-history-mode-e26598daa3d2
OR
https://gist.github.com/hclivess/cfbc8eddb1f5692c619036cb47072934
with rolling mode but sync started at the beginning and already use 50GB. I checked timestamp:
$ ./tezos-client get timestamp
2018–12–05T16:55:20Z
What I'm doing wrong?
Comment: I've had to take a snapshot and import it to garbage collect. Hopefully gc will happen automatically in the future.
Answer: Use the history-mode argument when importing the snapshot. These are the steps:
<code>rm -rf .tezos-node/{context,store,version.json}
tezos-node snapshot import "${SNAPSHOT_FILENAME}" --history-mode=experimental-rolling
tezos-node config init
tezos-node run --history-mode=experimental-rolling --rpc-addr=127.0.0.1:8732 --connections=20 --bootstrap-threshold=3
</code>
Answer: Im not sure that OP is importing a snapshot - seems OP simply wants to run a rolling node, and expects the node to sync itself with only the 5 latest cycles?


Intuition on Gibbs Free Energy

Question: In many places, I read that Gibbs Free Energy is called "free energy" because some of the enthalpy that comes from the chemical reaction becomes "waste heat" due to a change in the entropy of the system, and only the rest is usable as work. However, I cannot imagine how this is the case. Take an exothermic reaction with a positive change in entropy for example. Because $\Delta G = \Delta H - T \Delta S$, then we find that $\Delta G$ is more negative than $\Delta H.$ That is, more energy is released by the system than the enthalpy of reaction. How does this fit in with the "waste heat" explanation, that not all of the energy released is usable? There is more energy released now.
Answer: From Second Law of Thermodynamics viz. $$\Delta S_\textrm{sys}+ \Delta S_\textrm{res}\geq 0\,,$$ it can be concluded that $$W_\textrm{sys}\leq (U_1- U_2)- T(S_1 -S_2) \tag{1}\;.$$
Now, $$W_\textrm{sys}= \underbrace{W_T}_\textrm{pressure-volume/compression work}+ \underbrace{A_T}_\textrm{non-compression work}\;.$$
Putting the the first term on the RHS of $(1)\,,$ it yields,
\begin{align}A_T &\leq (U_1- U_2)- T(S_1 -S_2) - W_T\\ &\leq (U_1- U_2)- T(S_1 -S_2)+ P(V_1 -V_2)\;.\end{align}
Now, this is equal to the negative change of Gibbs energy $G$ provided the thermodynamic process is done at constant pressure and temperature.
So, that means,  $$A_T \leq G_1 -G_2\;.$$ Note the $\leq$ sign; this implies $(G_1-G_2)$ is the maximum value $A_T$ can attain.
Since, $\Delta G \lt 0\;,$ this implies $A_T$ is positive. Now, if the process is reversible, then the non-compression work $A_T$ is maximum viz: $$A_T= G_1 -G_2\;.$$
This definitely supports the term free energy as the decrease in $G$ gives the amount of energy "that can be 'freed' and made available for work".

That is, more energy is released by the system than the enthalpy of reaction.

Of course, the extra energy came from heat energy absorbed from the environment as the entropy of the products was greater than that of the reactants by $\Delta S\;.$
Answer: Free energy is the energy free to do work in the system.  One way for the entropy change of the system to be positive is for the products to have more moles of gas than the reactants.  The gas could be made to do work in a piston or turbine (or just push the atmosphere out of the way), allowing the system to release more energy than the heat released by the system.
Answer: The "heat tax" for an exothermic reaction comes from heating up the surroundings. Thermal energy can be converted to useful energy (e.g. heating up water to drive a steam turbine to generate electricity), but this can never be 100% efficient.
Research the Carnot cycle - a theoretical heat engine that gives the limit of efficiency in converting heat to work. Even assuming the impossible - perfect thermal isolation of components, no friction, etc. the efficiency of energy conversion is always <100%.

Intuition on Gibbs Free Energy


How does gravity interact with a photon?

Question: If photon is mass-less and gravity can interact only with matter, then how  does gravity alter the trajectory of light?
Comment: Maybe it's the curvature of the space time that affects the light?
Comment: @Archa It does.  The path of light is defined in terms of geodesics ("shortest small paths", loosely) in the space-time manifold, which are determined (in a certain sense) by the curvature.  But as Stan points out, a lot more than mass, or even mass+energy, contributes to gravity in GR.
Comment: It is perhaps worth noting that Newton could have modelled quite accurately the deflection of light using his corpuscular theory of light and the principle that gravitational acceleration is independent of mass (or the lack of it) http://arxiv.org/abs/physics/0508030
Answer: It is simply not true that gravity can only interact with mass. Rather, any long-range spin-2 force interacts with all energy-momentum equally, and it source is the stress-energy-momentum tensor. That is one way to state the equivalence principle.
Note that a massive object in its own rest frame has an associated energy $E = mc^2$, which under ordinary conditions is usually much higher than any stress terms (including pressure) or momentum (outside the rest frame). Thus one can usually pretend that gravity couples to mass, but it isn't so--rather, the gravitational charge is energy, and the entire stress-energy-momentum tensor couples to the gravitational field. This is analogous to how for electromagnetism, there is electric charge, but the electric currents also make a difference.
In the weak-field limit of general relativity, one can consider the fact that light is gravitationally deflected twice as much as a naive Newtonian prediction would be (for an object at the speed of light under Newtonian mechanics, that is) as the fault of light putting a pressure in the direction of its propagation equal to its energy density. But in general, the motion of a test particle is determined by its four-velocity and the geometry of spacetime only, and the light would just be a special case of having a 'lightlike' four-velocity.
Answer: What we call "gravity" is really just the distortion of spacetime. If spacetime was completely straight, there would be zero gravity. But the existence of a massive body is one of the things that can distort spacetime, so that "straight" lines are not straight anymore. We perceive that distortion as "gravity". It is the distortion that actually generates the gravitational force of attraction.
For a very crude analogy, imagine a lemon. As long as you're not squeezing it, the juice stays put, because no force is exerted on it. But when you squeeze the lemon, distorting its structure, juice starts moving around inside. The lemon is spacetime. The juice is anything existing in spacetime. Gravity is the distortion of the shape of the lemon.
Photons may not have any rest mass, but they move in a straight line. When there's gravity, straight lines are not straight anymore, and therefore photons curve around massive bodies.
Answer:
If photon is mass-less and gravity can interact only with matter, then how gravity can alter the trajectory of light?

The second part of your "if" clause is incorrect. It's mass-energy, not just mass, that gravitates.
Comment: -"If photon is massless and gravity can interact only with matter, then how gravity can alter the trajectory of light?" Electromagnetism can interact with light though *hint*