Are postdoc applications sometimes scored using a rubric?

Question: I am wondering if some postdoc positions are evaluated using a rubric, like when students hand in tests and the instructors grade using a rubric? If so, is whoever gets the highest score the person who gets hired? In case rubrics are used, are they publicly availabe?
Comment: This totally depends on the position, there's no standard way to grade them.
Comment: I voted to re-open because, while the answer to the question varies across countries, it is easily possible to give helpful comments! I was quite interested to see @FedericoPoloni's explanation of what happens in Italy. And, for the U.S., I think it's reasonable for people outside of the decision-making "elite" to wonder how decisions are made... especially with regard to issues about avoiding bias, etc.
Comment: Can you give a specific country?
Answer: In some countries, yes. This is for a position in Italy I am involved with (translated from Italian with the help of Google Translate):

The evaluation takes place through the attribution of a score, up to a maximum of 100 points, broken down as follows:
⦁ up to 10 points for a research doctorate or specialization diploma in the medical area;
⦁ up to 40 points for the following documented qualifications: degree mark, post-graduate diplomas, any contracts, scholarships, enrollment in doctoral or specialization schools, conference talks, other documented titles;
⦁ up to 40 points for publications and other research products;
⦁ up to 10 points for the possible interview.

The hiring committee first has to write a more detailed outline of how these items will be scored, before looking at the applications, and then proceeds to evaluate the candidates according to these criteria. There is still some space for informed judgement of the committee though; for instance the expanded rubric for the third item is:

The score is awarded considering publications that are relevant  with the research program and congruent with the scientific area of the call: based on their number (up to one maximum of 10 points); on their originality, innovativeness and methodological rigor (up to a maximum of 20 points); on the scientific relevance of their publication venue and their dissemination within the scientific community (up to a maximum of 10 points).
Comment: Side note: I am not a fan of this method either; it is the product of a system where malpractice and litigation were rampant, and bureaucracy has been introduced as a complicated method to prevent them.
Comment: @Buffy I've also explained the idiosyncrasies of this process here: https://academia.stackexchange.com/a/59771/20058 As I jokingly said, you might not be able to hire a Nobel prize if the rubric doesn't foresee such an applicant. Personally, I think that such a system introduces more issues than those it's supposed to solve. On the other side, I had a few PhD students hired by a large US institution and the hiring process was totally devoid of bureaucracy and went about like this: hey Massimo, what is X doing? Can I offer them a position? I wish we have this freedom too.
Comment: In Germany this is not mandatory, but I know some institutions that use scoring sheets particularly if they are afraid some applicants want to sue their way into a permanent position. I.e., this is used mainly to produce a paper trail that can be used in court as evidence against discrimination allegations (in Germany, the [potential] employer has to prove non-discrimination). This also includes conducting standardized interviews. The actual questions/scored characteristics are put together according to the actual job offered, i.e., the research project's requirements. It will not be revealed
Comment: @Buffy Yes, the winner must be the highest-scoring candidate.
Comment: @Buffy Once the scoring is done, there's no room for rejection (if I recall correctly, it's by law). Actually, even with this system, it's not uncommon to have recourses in front of a court where candidates declare to have been unfairly assessed, and sometimes the selection has to be redone. In any case, no selection committee in their right mind would decide to deviate from the score. In certain cases, to avoid any recourse selection committees make very detailed rubrics.
Comment: Does the highest scoring candidate necessarily and always get the position? Or is there room to reject one or all after the scoring?
Comment: to the candidates as rubric used (unless maybe in court). But you'll of course know what questions you are asked, and you may realize that the questions sound standardized and the interviewers work along a list of questions and write down notes.
Answer: Despite the fact that they are sometimes called "trainees", from an administration perspective postdocs are generally managed as employees rather than as students.
This means that you should think of a postdoc application like a job application, rather than like any of the program admissions that you may have faced before.
Critically, this means that despite the conflation of "applying to a program" vs. "applying to a laboratory" in many discussions, the hiring process is usually completely different:

Graduate students typically apply to a department, which handles all applications together via an admissions committee. Professors may be able to "earmark" a student by saying "I want that student / I will support that student", but ultimately it is the department and not the professor that admits the student.

For most postdocs, the professor is the hiring manager and has complete discretion on how their make the decision as long as it is within the institution's employment regulations.

There are exceptions to these generalizations, such as organizational fellowships, but overall you should expect there to be absolutely no uniformity across institutions or even within a single institution as to how postdoc job applications are handled.
Answer: I can only speak to how I evaluate candidates at a US national lab. The posting (any posting) will have a set of Required and Desired attributes. HR screens for the Required, and I generally ignore applicants that don't meet those (although I do scan to see if HR messed up - I've learned to make the Required ones as easy to understand as I can, so no technical terms).
The Desired attributes are for me to score, and I usually have 5 or so. I do it very simply - a 1 is "does not meet", a 2 is "perhaps meets", and a 3 is "definitely meets". Add those up, and one typically get a few general groupings. There are quite often a number of 'does not meet any desired attributes', some with 1 or 2, and then those with 4-5 or so. Normally there is one "high point", but some strong candidates close behind.  I'm looking for the top 3 or so, if things are close I'll look at a few more but usually will only select 3. Then I'll set up interviews for about 3 candidates. The choice to hire is based solely on the interview results - the "rubric" was only to get to the interview pool. The 'high point' candidate is not always the selection.
Answer: I think that is unlikely in the US, at least. Much more likely is a meeting of interested faculty (one or more) who hash out the merits of candidates. They might use something like a rubric to make sure that all factors are considered, but it is really individuals making decisions about who might be best to work with and such.
I'd also guess it is impossible to create a valid rubric to be used as you suggest. There are too many variables and they have varying importance.
I can't rule out that it has happened, though.

Since the question was changed to "sometimes" I'll add the following. Yes, everything happens "sometimes". But in the US I think that faculties would consider a rubric (such as the Italian model) to be overly limiting. The problem is that you can't take advantage of opportunities that arise only after the call is published and applicants appear in the pool.
One of my (fondest) memories is that of a bunch of senior (male) mathematicians deferring to a junior (female) faculty member in the choice of a postdoc. Just by chance, an applicant turned out to be especially well qualified as a collaborator of the junior colleague and their work together could be expected to benefit both. This would, in particular, aid her in gaining tenure. But that application was serendipity that they were able to take advantage of because they weren't overly bound (and were a collegial bunch).
In general, different people have different characteristics and it is IMO not possible to build a rubric that sufficiently covers the ground unless flexibility is also possible.
Comment: Oh, ok. I thought it would be something like: grade the research statement out of 5, take the number of published papers and multiply by a certain number depending on the prestige of the journal...
Comment: Seems far fetched, actually. Judgement is more important in such decisions.
Answer: There's no general answer for this because it varies immensely between countries, fields, and individual research groups––and sometimes even within them!
How hiring works generally
At one extreme, some positions will put out a call for applications, collect a bunch of them, and have them reviewed by a committee. I've never heard of a process quite as systematic as the Italian one described in Federico Poloni's answer, but it would not be odd for them to use  some sort of rubric or checklist to assess candidates.
At the opposite extreme, some postdocs are arranged without much formal process. An applicant contacts a potential PI and expresses interest in joining their group. If the PI reciprocates that interest (and has money, space, etc), then a position is created and that person is hired. The applicant might be invited to give a talk or meet with other group members to help the PI make a decision, but there is no structured process and the only "competition" against opportunity costs (e.g., Will a better candidate appear in the near future?) There may be some minimal bureaucratic component, like checking that the person has a PhD, or posting a job ad, but it is almost entirely pro forma.
Crucially, both can even happen in the same department. My PhD department participated in a School of Medicine-wide postdoctoral program that was reviewed by a committee, but many postdocs were hired via informal channels.
How to get yourself hired
I'd guess you want rubrics so you can maximize your own chances of getting hired.
Unfortunately, there's no magic formula and even the same lab may have different priorities at different times: funding with tight timelines and specific deliverables often need someone who knows the field/techniques already; more open-ended funding like an NIH R01 might instead be good for someone promising who wants to learn.
In general though, all the usual markers of academic success help (papers, presentations, fellowships, etc). Interactions with the PI—either directly or via strong letters—can also make the case that you've got knowledge and skills that may not be reflected on your CV. Asking trusted mentors (your thesis committee?) may give you a rough assessment of your chances.
Another way to give your applications (of all stripes) a leg up is to clearly explain what you hope to bring to this particular lab and what you hope to get out of your time there. I think this is often neglected, but is also completely under your control. Good luck!
Answer: In the U.S., in math, I have never seen anything completely determined by "rubrics"... despite a long tradition of trying to make decisions by algorithms based on various numbers. :)
In math, we mostly do not have "labs", and funding is more centralized, etc., so there is less reason to give final decision-making power to individual faculty.
And, yes, in recent years, there has been a somewhat-reasonable push to make hiring and admissions fairer by having some quasi-objective rubrics play a larger role, as opposed to old-boy-network criteria. A fundamental problem is that "to compare" we seem to need "numbers", and a valid way of assigning numbers ... and adding them up... ?!?!? ... is very difficult, if not impossible. As in "really, can we quantify the prestige of journals?". And what weight to give...?!?
On another hand, the hiring/admission processes in math in the U.S. are less closed-to-outsiders than they were years ago, I think. Rubrics may help a bit, but I think even more important is a change in attitude/culture, realizing that the old almost-purely-networked culture had many implicit biases.
Comment: It seems like quantity of papers is very important. I was looking at Robert Steinberg's collected works and I don't think Steinberg would be able to get a postdoc at most places in the U.S.
Comment: At the risk of sounding elitist, I surmise that second-rate mathematicians value quantity of papers more and will select for postdocs who will in turn become second-rate mathematicians.
Comment: True, number of papers is a number. And, somewhat more subtly, some people will hire postdocs who don't make them feel threatened... All sorts of nonsense is possible, and hard to avoid by pseudo-objective rules. Yes, even not pathologically, not-so-good mathematicians may understand lukewarm mathematics better than bleeding-edge stuff, etc. As in many contexts...
Comment: Do you think academia is a meritocracy? I have heard that opinion from a senior mathematician. Doesn't it depend on how merit is measured? Merit is a social construct.
Comment: Certainly the pretense is that academia is a meritocracy. But, yes, there is a significant self-referential aspect to that, in addition to the "constructed" aspect (which, in may, would be denied by many, as a matter of principle :)
Comment: I think that if merit were measured by how far people got based on where they started and took into account things like family background (e.g., were your parents professors?), academia would look very different and would be better in many ways. However, the prevailing ethos seems to be the idea that unfair advantages have minimal impact and that success is all due to "innate talent" and "giftedness."
Comment: @cgb5436: From Paul Halmos who attributed it to Andre Weil: First rate mathematicians hire other first rate mathematicians.  Second rate mathematicians hire third rate mathematicians.
Answer: In simple words, it is not necessary. However, it seems that the use of rubrics is becoming increasingly popular and is receiving unprecedented attention.
See here.
Even, the Virginia Tech Presidential Postdoctoral Fellowship RESEARCH FRONTIERS & CYBERSECURITY Proposed Scoring using Rubric. See here.
Comment: Wow! That's interesting.


Pgpool - 3.5 configuration

Question: [enterprisedb@pgdvdb1dr bin]$ 2017-06-20 11:34:41: pid 103313: WARNING:  could not open configuration file: "pgpool.conf"

2017-06-20 11:34:41: pid 103313: DETAIL:  using default configuration parameter values
2017-06-20 11:34:41: pid 103313: FATAL:  initializing pool password, failed to open file:"/mnt/hgfs/edb-postgres.auto/pgpool/staging/linux-x64/pgpool/etc/pool_passwd"
2017-06-20 11:34:41: pid 103313: DETAIL:  file open failed with error:"No such file or directory"

[1]+  Exit 3                  ./pgpool -n

Comment: As error shows related to password error?
Comment: how to configure the pgpool in same server using different port and how to start and use the pgpool i need the steps can you ??????@Md Haidar Ali Khan
Comment: What is your O.S Environment?
Comment: rhel 7.2 and am getting same this error only
Comment: [enterprisedb@pgdvdb1dr bin]$ ./pgpool
2017-06-20 15:09:41: pid 2148: WARNING:  could not open configuration file: "pgpool.conf"

2017-06-20 15:09:41: pid 2148: DETAIL:  using default configuration parameter values
Answer: you need to set up backend PostgreSQL servers for pgpool-II. These servers can be placed within the same host as pgpool-II, or on separate machines. If you decide to place the servers on the same host, different port numbers must be assigned for each server. If the servers are placed on separate machines, they must be configured properly so that they can accept network connections from pgpool-II.
if you will place two servers within the same host as pgpool-II, let's  suppose that you want to assign 5432, 5433 port numbers respectively. To configure pgpool-II, edit pgpool.conf as follows.
backend_hostname0 = 'localhost'
backend_port0 = 5432
backend_weight0 = 1
backend_hostname1 = 'localhost'
backend_port1 = 5433
backend_weight1 = 1

For backend_hostname, backend_port, backend_weight, set the node's hostname, port number, and ratio for load balancing. At the end of each parameter string, node ID must be specified by adding positive integers starting with 0 (i.e. 0, 1, 2, …).
backend_weight parameters are all 1, meaning that SELECT queries are equally distributed Between two servers.
Starting/Stopping pgpool
$pgpool

The above command, however, prints no log messages because pgpool detaches the terminal. If you want to show pgpool log messages, you pass -n option to pgpool command so pgpool-II is executed as non-daemon process, and the terminal will not be detached.
$ pgpool -n &

The log messages are printed on the terminal, so the recommended options to use the following.
$ pgpool -n -d > /tmp/pgpool.log 2>&1 &

The -d option enables debug messages to be generated.
To stop pgpool, execute the following command.
$ pgpool stop

If any client is still connected, pgpool waits for it to disconnect, and then terminates itself. Run the following command instead if you want to shutdown pgpool forcibly.
$ pgpool -m fast stop

For further your ref Here

Pgpool - 3.5 configuration


Can I use an 8" dado blade set in a 10" table saw?

Question: I have a 10" table saw... this is probably a stupid question, but can I use an 8" dado blade set in this saw?  Is one only supposed to use 10" blades in a 10-inch saw?  I read on some contractor's blog that one should only use saw blades that are within the range of blade sizes acceptable for a particular table saw (per that saw's documentation)... but for the life of me I wasn't able to find mention of the range of allowable blade sizes for this saw last night in reading the manual.
Answer: There is NO problem with using an 8 inch dado blade on a 10 inch saw. In fact, it is quite common to do so. I use an 8 inch stack on my Delta contractor's saw with no problems, and before that, I used an 8 inch wobble dado.
You certainly would not want to use a 12 inch blade on a 10 inch saw, as that large of a blade might have clearance problems as it is adjusted. Use of a larger blade also causes somewhat larger tip speeds, so that might potentially cause problems. (Unlikely, but possible, since the differential in tip speed would be only 20%.) Perhaps these issues are what the author meant when they made that statement.
In going to a smaller blade diameter though, the only question is whether that blade will be able to reach the surface of your table. On an 8 inch blade there is no problem.
Comment: The tip's idle speed is actually slower, as the diameter is smaller.

The actual tip speed under load can be higher because the asserted force (torque) on a smaller diameter is higher.
Comment: It is actually _recommended_ that you use a smaller dado set. Consider how much thicker each of the outer cutters is than a standard single blade, then you're using 2 of them and adding in one or more chippers. You're putting a lot of mass on the arbor of the saw. That mass makes the motor work _much_ harder and a 10" dado set on a 10" saw would likely be too much for all but the highest-end saw's motor to spin.
Answer: For what it's worth I've used a 6" stacked dado set in my small 10" saw for years without any issues.  My understanding is that dado blades should always be smaller than the saw's rated blade size due to the increased load of cutting a wide dado over just cutting a saw kerf width.  The smaller diameter means your saw will be able to exert more force on the teeth than it would with a larger diameter blade.
Are you sure the blog you saw wasn't referring to not using blades that are larger than the saw's rated size?  I could see issues with that but I'm not sure what the problem might be with using a smaller blade.


Who is the most influential Sith? (Canon and EU acceptable)

Question: This question is something of a companion to this one. I am interested in finding out who the most influential Sith (or other Force entity) was in the Star Wars universe? Influence is not the same thing as raw power - regardless of personal abilities, which individual had the broadest and longest overall effect on the Galaxy?
Comment: [This guy](http://tubulamarok.free.fr/starwars/sw6.2004-palpatine.gif), perhaps?
Comment: Without a solid definition of "influence", this question borders heavily on soliciting opinion-based answers.
Comment: Influential how? Palpatine effectively took over the entire galaxy and had the most political influence. Darth Bane set the course for the rules of the Sith, arguably making him the most influential over the Sith order. Anakin killed the emperor, arguably making him the most influential as he overthrew the Sith's control.
Comment: You did say Sith or other Force entity. If you include all force entities I think there's a simple answer. I'll post below.
Answer: THE FATHER
"The Ones" (http://starwars.wikia.com/wiki/The_Ones) were the most powerful force wielders ever. "The Father" (http://starwars.wikia.com/wiki/Father_(Mortis)) in additional to be the most powerful in the force was the most influential.
"The Father" kept "The Son" and "The Daughter" at bay, and made sure there was balance in the force.
"The Father" also made sure the that Abeloth didn't destroy or ruin the universe.
Entire religions were spawned after "The Ones."
They've also been around the longest going back to 1,000,000 BBY.
In the Star Wars Universe nobody has influenced the force, or the universe more than "The Father" as he kept things in order for all that time and had a huge responsibility, without him things would have fell apart.
Since you included "force entity" in your question, this is a clear cut answer.
The Clone Wars "Overlords":

The Father: You cannot imagine what pain it is to have such love for
  your children and realize that they could tear the very fabric of our
  universe.
AS: I don't understand.
The Father: It is only here that I can control them A family in
  balance. The light and the dark. Day with night. Destruction replaced
  by creation.
AS: Then why reveal yourselves to us? There are some who would like to
  exploit our power. The sith are but one.
The Father: Too much dark or light would be the undoing of life as you
  understand it.

So the guy keeping "life as you understand it" together and holding the force in the balance for over a million years is definitely the most influential force wielder ever.
If you're going by just the movies, then "Darth Vader" as he was the most hands on and the stories were most centered around him and his character. You could also choose Palpatine as Richard suggests. Palpatine was a mastermind strategist.
But there wasn't anybody in the series that influenced the universe and for as long a period a time as "The Father" if you're including all force wielders.
Comment: Form you're answer, it's sounds as if The Father was neutral and not a Sith at all. The OP is looking for a Sith.
Comment: @Daft in the description of his question he included "Or other force entity." The father is a force entity. If that is incorrect the OP should pull those words from the question. If he wants to include all force wielders as the questions states, then there is no more influential person in the SWU than The Father(Mortis).
Answer: It's hard to gauge who was the most influential Sith without a clearer definition of exactly what influence is.
But Darth Bane could conceivably be in the running, he created the Rule of Two in an attempt to put an end to all of the in-fighting within the Sith:

Darth Bane, born under the name of Dessel, was the Sith'ari and the Dark Lord of the Sith responsible for creating the Rule of Two.

Another contender could be Darth Andeddu, he is beleived to be the first Sith Lord to prefix his name with the title: Darth.

Darth Andeddu, also referred to as the Immortal God-King of Prakith, was an ancient humanoid male who reigned as Dark Lord of the Sith, and was dubiously thought of as the forebear of the "Darth" title.


What is the meaning of this error in MATLAB?

Question:
Warning: Failure at t=6.137539e-04.  Unable to meet integration
  tolerances without reducing the step size below the smallest value
  allowed (1.734723e-18) at time t.
  In ode15s (line 730)
    In khademi (line 59)
Comment: Your choice of solver could be discussed if you can share the details of the ODE being solved.
Answer: All of the MATLAB ode solvers adjust the integration step size to try to keep the error in the solution less than certain prescribed tolerances. If the error exceeds these tolerances, the step size is reduced until it reaches essentially zero (1.734723e-18).
Usually this error message arises because the problem is ill-posed. If you terminate the solution at some value of t<6.137539e-04 and look at the solution
at that time, there is a good chance it will be very large (i.e. the solution is
going to infinity or negative infinity).


How strong were the Maiar, physically speaking?

Question: Is there any mention of it anywhere? As strong as humans? As strong as orcs? Stronger, perhaps?
Comment: Seven.  They are seven strong.
Answer: Not too much is written on this matter, because the Maiar, being divine spirits, are not necessarily bound to a single body, and thus could, theoretically, be clothed in bodies that are powerful physically one day, and others the next. However, the Maiar are usually aligned with some sort of power or aspect, and the forms they choose reflect that. Some aren't more powerful than humans, some are much more impressive.
Here are some Maia whose physical powers we are familiar with.
Gandalf
Gandalf, who was known as Olorin in Valinor, is a Maia of Lorien, who learned kindness and patience from Niena. Of Gandalf, it is said that he took the form of Man and Elf when walking among the people of Middle Earth, and thus we can assume that his physical power is at least equivalent to those. Despite seeming aged, we know that he is physically fit as a much younger man, or even superhumanly so, in a pinch: we see him riding for days in The Lord of the Rings, wielding his sword, standing tall in front of Theoden, facing the Balrog and carrying Faramir, a not-small man, with ease:

Then Gandalf revealed the strength that lay hid in him; even as the light of his power was hidden under his grey mantle. He leaped up on to the faggots, and raising the sick man lightly he sprang down again, and bore him towards the door.

(That last from The Return of the King, ch.7, The Pyre of Denethor, and thanks to @JimmyShelter for the reference)
The Balrog
The Balrog of Moria, Durin's Bane, and the rest of his Balrog companions were also Maiar, described in the Valaquenta, the second part of the Silmarillion, as:

[T]he Valaraukar, the scourges of fire that in Middle-earth were called the Balrogs, demons of terror.

and later:

With their whips of flame they smote asunder the webs of Ungoliant, and she quailed, and turned to flight, belching black vapours to cover.

Nothing explicit is mentioned about their physical power, either there or in the Lord of the Rings, but they are described as beings of might, inspiring awe and fear in allies and enemies alike. In almost all cases where someone encounters a Balrog - including some of the mightiest Noldor of the First Age, like Feanor or Maedhros, they are defeated by the Balrogs.
Eönwë
Eönwë doesn't get a lot of screen time, but he does lead the forces of Valinor against Melkor and his armies during the War of Wrath, at the end of the First Age. He is described in the Valaquenta as:

Eönwë, the banner-bearer and herald of Manwë, whose might in arms is surpassed by none in Arda.

Implying that he is not powerful in a mountain-moving way (the way that Tulkas, of the Valar, is), but he could outfight any opponent, mortal or Maia.
Sauron
And finally Sauron, everyone's favorite Valar wannabe. Sauron was originally a follower of Aulë, as can be seen from his skill at crafting rings later on, but he was also quite impressive in battle, as can be seen during the War of the Last Alliance at the end of the Second Age. In the LotR movies he is portrayed as standing 20' tall and cutting huge swathes through the ranks of elves and humans, but in the text, specifically of the Akallabeth, this is slightly more toned down:

But at the last the siege was so strait that Sauron himself came forth; and he wrestled with Gil-galad and Elendil, and they both were slain, and the sword of Elendil broke under him as he fell. But Sauron also was thrown down.

So Sauron was certainly more powerful than the average man, and could out-wrestle (I'm assuming we're not talking Greco-Roman here) the High King of the Elves and the scion of the Kings of Numenor, but he was cast down. And after the ring was cut off, he lost even that impressive body, and could afterwards not muster even that amount of physical power.
Summary
All in all, the Maiar's physical power varied. Melian or Saruman could probably not face a determined warrior in single combat, but others could be mightier than most mortals. This wasn't necessarily indicative of their overall might, but of their personal roles and orientations.
Comment: Gandalf is stronger than the average human but keeps it hidden: "Then Gandalf revealed the strength that lay hid in him; even as the light of his power was hidden under his grey mantle. He leaped up on to the faggots, and raising the sick man lightly he sprang down again, and bore him towards the door."
Comment: @JimmyShelter Good quote, I'll edit it in.
Comment: And of course, we also run into dragons like Smaug and Glanrung in the books, and they are originally Maiar.
Comment: Balrog fought by Gandalf, known as Durin's Bane, was described as ,,stronger than a strangling snake" when they both grappled each other, wrestling, hewing with sword in case of Gandalf, or clutching in case of Balrog and they did so for many days, first Balrog survived cave-in, he was briefly buried under rubble, then survived the fall into immeasureable chasm hitting icy cold water at high speed (Gandalf during the long fall was also burned), so in physical bodies Ainur no matter Valar or Maiar appear quite powerful.


Long-term backup storage media

Question: Rumors say CDs and DVDs won't remember your data longer than ten years. Are there backup media that do better?
Comment: I've definitely used CDRs that are >10 years old with no issue - but they've also been stored well and not handled much.
Comment: *> Rumors say CDs and DVDs won't remember your data longer than ten years.*   I heard 50-100 years for both of them, and this was back when each was still new (i.e., the manufacturing processes—*should*—have improved since then, leading to longer lifespans).
Comment: I had a CDR unreadable after 16 years
Answer: Hard Drives. Space is dirt cheap these days, you can grab a few TB worth of internal hard drives at a fairly low price. Even external hard drives aren't too expensive.
Comment: Are you sure you will still be able to read a contemporary hard drive in the future? For example, could you connect a 20 year old hard drive to a modern PC to read the data off it?
Comment: @ Matthew Lock: there is no way, a hard disc will outlast optical media.
Comment: Ability to read current supports in the future is a big problem of backup, no matter the support. Solutions involves copy backups to newer technologies as soon as they appear and/or keep old systems alive just for the purpose of retrieving backups.
Comment: You might think about getting a docking station to go with that, so you can keep buying cheaper internal hard drives and still switch them around easily. Internal hard drives stack better, too.
Comment: The other day I connected my last remaining PATA backup drive for testing. The spindle grease was beyond seized. While the data was more than likely fine, the drive had still effectively died in storage.
Comment: Hard drives last LESS than 10 years on average, so except if you are very lucky with your hdd, this answer does not fit OP's criteria.
Answer: Regarding longevity, you'll probably accumulate data too fast for the media to be a problem.  7 years from now you might have enough DVD's to fill a couple Blu-rays.  7 more years and you'll have a stack of Blu-rays ready to consolidate on whatever the next big thing is.
For now, Patrick McFarland's How To Choose CD/DVD Archival Media comes out in favor of DVD+R, specifically Taiyo Yuden's:

To begin with, I do not recommend
  CD-RW, DVD-RW, or DVD+RW media in any
  form for permanent storage. This is
  mostly a no-brainer, but those discs
  are meant to be able to be changed
  after burning, and they are simply
  unsuitable for long-term archival
  storage. I also do not recommend DVD-R
  media due to DVD+R's superior error
  correction and burning control.
That said, I recommend Taiyo Yuden
  media across the board. Taiyo Yuden
  currently manufactures 52x CD-R, 16x
  DVD-R, and 8x DVD+R media in normal
  shiney silver, inkjet printable, and
  thermal printable forms. Taiyo Yuden
  may be one of the most expensive (if
  not the most expensive), but their
  media quality is unsurpassed.

A recent update shows he still affirms this position.
I thought I read somewhere that the Library of Congress uses MAM-A archival gold DVD's but considering the cost I stick with TY's.  I usually purchase through http://www.rima.com, while McFarland recommends another vendor in his article.
Answer:
Rumors say CDs and DVDs won't remember
  your data longer than ten years.

You just said it: RUMOURS! :)

The Optical Storage Technology
  Association (OSTA) has published the
  following longevity estimates for
  recordable optical media:
Manufacturers' estimated recorded life
  span.
CD-R: 50-200 years
CD-RW: 20-100 years
DVD+R: 30-100 years
DVD+RW: 30 years
BD-R 50+ years

So, chances are that you may not live long enough to prove these estimates wrong! :)
Now compare that to the average lifespan of a platter hard disk (2-10 years). Optical media win that contest hands down.
And then there is the good old stone tablet which will last a couple of thousand years. But the data density of 0.001 kbit/kg is a bit of a showstopper. :P
But in IT, the Cranberry Diamondisc DVD is considered to be the Holy Grail of long term storage, they boast a life span 1000 (one thousand) years. Of course it requires special hardware to burn these discs.
Comment: i don't think that there is much of a difference, it's probably worse if you don't fire up the discs every now and then, corrosion being its worst enemy. hard discs aren't really made for long term storage.
Comment: there's a fair amount of anecdotal remarks on cds not lasting particularly long.
Comment: YMMV of course, and only one set of backups isn't the best strategy anyway. but recommending platter HDDs instead of optical media because they last longer is plain wrong, they're cheap and fast alright but they're not really a choice for long term storage. they are no match for the longevity of CDs or DVDs. even magnetic tape lasts 6 times longer than the average life span of a hard disk.
Comment: hard disks being used or hard disks written to, disconnected, and put in a labelled box?
Answer: I'm not sure hard drives are any better than CD/DVD long term. The only way to be really sure is to keep checking the data and refreshing it.  There are CD's/DVD's that are specifically designed for long term storage but as always these are more expensive.
Answer: I think it has to do with how much you're willing to spend. I've thought about this in the past and the best solution I could come up with was a NAS with 2 large HDDs in RAID 1 configuration. This way you're protected from HDD failure and I'm pretty sure that Ethernet will still be around 10 years from now. Only worry is if the NAS itself breaks down, so you'd need a quality one.
Answer: From http://www.superwarehouse.com/HP_5.2_GB_Magneto_Optical_Disk/88146J/p/54344:

HP magneto-optical rewritable
  cartridges allow virtually unlimited
  read/write cycles, making them the
  ideal choice for data management in
  information-intensive environments. HP
  write-once cartridges are designed for
  permanent storage of data that can't
  be altered or erased. Both disk
  formats have an archival life of 100
  years...
Answer: Paper backups using an efficient encoding scheme also remain an option. It is not handy and takes a lot of space, but it is robust and long-lasting.
Comment: Paper also degrades with time, just like any other medium. The problem with paper is that you cannot automate curation (ie, repairing bit errors). Indeed, most inkjet printed photos won't even last more than 10 years (the colors will wash out), and the data density is very low (~100KB max with tiny characters and decoding using a computer program). Optical discs are pretty much the same idea as paper but miniaturized, and it can also be automated because there is a norm for writing and reading the data. See a [longer explanation and studies here](http://superuser.com/a/873260/157556).
Answer: I think the question that must be asked is "how long-term is long-term"?
Quality paper is probably the most efficient low-end long-term storage currently known(300+ years).
But if you're looking to archive records in the event of nuclear blast, you might try etchings on metal in a can in a cave.
But if you want to store company records for 50 years, hard disks disconnected and stored in a vibration-less environment together with paper documents on the interface & data formats is not a bad plan.
But if you want to publish historical-class data for the next 200 years, ie, you're investigating for a library or similar institution, you want to make sure that the information is usable when we go to The Hypernet, so you might be investigating a redundant array of cloud data storage centers from different companies with a common query-able interface published on the current Internet.
But if you want to archive historical-class data, you want something that is probably similar to a ROM-style hard disk. (I'm taking a guess that those exist for long-term archive storage).
But are you storing text? video? pictures? binaries? Each of those has different information characteristics and can be stored a little differently.
There's no 'right' answer here until you narrow your focus a bit.
Answer: And now you can store it for as long as 1000 years: http://www.tomsguide.com/us/DiamonDisk-DVD-Storage-Cranberry-Thousand,news-5112.html
Answer: depends on your data volume

USB flash drive- I sill have one 129 MB survived after washing in a machine and after all these years still works. When you start feeling that USB standart start to disapear or speed start to differ too much (i.e. USB 5.0 is the current standart)- transfer to the next new thing before is too late
or some skin for CD/DVDs like this
Answer: The only way to guarantee long life is via redundancy. Keep 2 backup copies of everything, as it's unlikely that both will go bad. Try to vary the media types, for example for DVD don't use the same manufacturer for both copies, or use two hard drive, or one hard drive with DVD/Blu-ray copy.
The advantage of a large hard drive is that you can verify it regularly. Also, the SpinRite utility, available from http://www.grc.com/sr/spinrite.htm and costing $89, can recover a hard disk and even refresh it magnetically so the recorded data won't magnetically fade out with time (but it only works on internal drives).
Answer: Tapes seem to be a good option for long term and big volume archiving.
Slashdot - Offline Storage for Hard Drives?
Flash drives might be worth researching too.
Answer: DVDs are very good storage mediums, but Blu-Rays HTL (like Panasonic's) are very stable and they are probably the longest lasting storage medium currently available for consumers. They are highly resilient to light degradation and also to humidity to a certain extent. Even big companies such as FaceBook are now using optical discs in automated robotic assemblies for long term cold storage of data.
Blu-Ray discs should last decades, but there is no way to precise the average lifespan of storage mediums more than that simply because either the technology is too new, or because nobody funded such a long running scientific study, so nearly every estimates are done using artificial aging. Artificial aging is very nice to quantify the resilience of a storage medium against natural damages (such as light and humidity, the two biggest factors of degradation), but they can't give a precise estimate on how long exactly the medium will last. I talk about such scientific studies here.
Also, do not believe claims that such medium is going to last for centuries or millenias (such as M-Discs or DiamonDisc) without an independent scientific study behind, most often these claims are baseless (M-Discs have been found to be not more resilient than Blu-Rays, but they are way more expensive! And they also have a defect on the outside plate glue which may make M-Discs totally unreadable in only a few years from now!).
Also, not all Blu-Rays are equals: some brands will be way more resilient than others. And conversely, the optical writer you use will impact the resiliency of your written discs. Refer to studies to know what to choose (if the optical writers are still available...).

Long-term backup storage media


Why symbols have to be upsampling, if the symbol rate and sample rate is same what happen?

Question: In digital modulation process, after constellation mapping and before pulse shaping, the symbols are upsampled with the number L(samples per symbol). At this moment, why symbol have to be upsampled, if the symbol rate and sample rate is same what happen?
Comment: If upsampling was not applied, and the symbol rate and sampling rate were the same, it would mean that every sample is a new symbol. This might cause decoding errors in low SNR. I would imagine the upsampling operation is done to perform the correlation operation on the discrete samples.
Answer: The baseband information-bearing signal $s(t)$ is a train of time-shifted orthogonal pulses: $$s(t) = \sum_k a_k p(t-kT),$$ where $a_k$ is the sequence of symbols and $T$ is the symbol rate. The problem is, how to generate this signal in Matlab (or any other discrete-time numerical language)?
To start, note that the $j$-th pulse $a_j p(t-jT)$ can be written as $$a_j \delta(t-jT) \ast p(t).$$ Here, the pulse $p(t)$ is interpreted as the impulse response of a filter (the "pulse-shaping filter"), which allows us to write the pulse as the result of a filtering operation (a convolution). If we define the train of impulses $\Delta(t) = \sum_k a_k\delta(t-kT)$, then the entire pulse train may then be written as the convolution $$s(t) = \Delta(t) \ast p(t).$$
This signal is easy to generate in a computer. Assume that the sampling frequency is fs, the sampling interval is Ts = 1/fs, and the symbol interval is T=LTs for integer L, which is the number of samples per symbol. Assume also that we have a vector of symbols ak, and samples from the prototype pulse p. Then, Δ = upsample(ak, L) is the discrete-time equivalent of $\Delta(t)$, and
s[n] = conv(Δ, p)

is the discrete-time equivalent of $s(t)$.
Comment: Thank you so much.
Comment: You're very welcome.


Can I grow an Oak Live Tree in a large container to keep it around 20 ft high?

Question: I'm new here. My partner and I are getting married and we are relandscaping our garden as our wedding gift. He loves Coast Live Oaks (Quercus agrifolia) and it'll mean a lot to us if we can plant one or two. That area of the garden is about 30 feet wide. Way to small for a tree that grows up to 85 feet high and 35 feet wide.
Can we plant a Coast Live Oak in a big container, wether above or under ground, to keep the roots and the tree about 20 feet high and 15 feet wide? Thanks in advance for your answers.
Comment: what is your location, your growing zone? Plants in pots are being in a colder zone so we need know how cold it gets
Comment: It might be feasible if you are willing to pollard regularly
Answer: I'm afraid not, not even in the medium term. The tree is unlikely to reach the size you mention contained in a pot because of root restriction; whilst it may remain healthy for a year or three if grown from seed or a small sapling, it will not do well contained in such a manner. This is one of those trees that produces a large and deep tap root, as well as large lateral roots, and growth of the taproot won't be possible in a container; this will compromise the tree's growth early in its life. If you bury the container, the only way the tree will grow on well is if it manages to punch through the bottom of the container and access the soil around and about. It is likely to do that, and when it does, it might as well be growing directly in the ground, in terms of height and spread as it grows. Burying the container confers no advantage in terms of restricting its growth otherwise.
Comment: There are oak bonsai, so you may get in a container, but probably it is not what you are asking (in such case add it in the question).
Answer: We live in Whittier California. We have an oak tree in a container that is 18 years old. Have had to get much larger containers through the years. The current container weighs about 500 pounds. The oak tree is currently about 12 feet high and 10 ft wide. It is possible to do what you want to do.


Can you recommend a command line JavaScript interpreter?

Question: I would like to try out an AES encryption facility: https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/rollups/aes.js But without using a browser, with a command line tool, if it exists at all. Which can import this aes.js file, and I can call the different functions from a REPL, or just interpreting a script which utilizes this aes library, and gives output on STDOUT - without a browser.
Answer: Node can do this. Download the file to a local ./aes.js or something, and then start node prompt and:
> .load aes.js

Bam
Unless by 'or' you mean that you need both to be able to use in from a REPL and  import it from a script. I don't know if it's possible to import unexported names from another file (the special .load command-line thing seems to dump the code into the current scope). But if you can access the source of the library instead of the bundle or install it with NPM, you should be able to import it with const CryptoJS = require('crypto-js') (cause node needs module.exports to be used in order to import names from it).
Answer: Mozilla developers had the exact same idea, and there is a page in their docs about this:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Shells

The following is copied from there (source page last updated Aug 19, 2021):
Standalone JavaScript shells
The following JavaScript shells are stand-alone environments, like Perl or Python.

Node.js - Node.js is a platform for easily building fast, scalable network applications.
GraalJS - A high performance implementation of the JavaScript programming language. Built on the GraalVM by Oracle Labs.
ShellJS - Portable Unix shell commands for Node.js

List of JavaScript shells
The following JavaScript shells work with Mozilla.

Firefox has a built-in JavaScript console, which support multi-line editing.
Babel REPL - A browser-based REPL for experimenting with future JavaScript.
ES6Console.com - An open-source JavaScript console to test ECMAScript 2015 code inside the browser.
jsconsole.com -- An open-source JavaScript console with the ability to easily link to particular expressions
JavaScript Shell (web page) - also available as part of the Extension Developer's Extension
Comment: Nothing to add that justifies a standalone answer, but this ["ECMAScript 2016+ compatibility table"](http://kangax.github.io/compat-table/es2016plus/) shows an elaborate comparison of the different engines with respect to standards and compatibility.


How to calculate the token price of already deployed ERC20 tokens

Question: I am creating a smart contract, so inside that I have to pass the token in contract and the value of ether will be calculate on behalf of token price please help.
Answer: You can only set the price of a token during its initial distribution phase (e.g. the crowdsale, ICO, etc.). Once the tokens have been initially sold, and they are out in the real world, then the price is set by supply and demand; you have no control.
If you are currently writing your token distribution contract (this is separate to the ERC-20 contract itself), then you can set the price there. Have a look at these (OpenZeppelin) example contracts.
However, your question is a bit ambiguous. If you've already distributed your tokens, then you won't be able to set the price. If you've published the ERC-20 contract but haven't distributed the tokens, then you should still be able to run your distribution phase using your distribution contract.
Comment: i want to make crypto to crypto smart contract where i need to sell erc20 token and on buyer side i need to calculate the price which i have to send to seller can you please describe the calculation because i have a price of token.
Answer: I think this is impossible, because the price is determined by traders on exchanges.
Comment: but if i have token price than?
Comment: u can't get data like this: uint public price = 'some.api/price', u have to pass price everytime when u need: function funcWhereYouNeedPrice(uint memory _price) onlyOwner external { "operations with _price" }
Comment: but this is bad idea too, because u need to wait when transaction will be mined and price can be changed. so u will get not actual price. don't use this in financial operations
Comment: so what is the correct way to buy token behalf of eth? because i want to make crypto to crypto smart contract where i need to sell erc20 token and on buyer side i need to claculate the price which i have to send to seller.


Maximum weight perfect matching in general graphs

Question: Let $G(V,E)$ be a graph (not necessarily bipartite), where edge $e \in E$ has weight $w_e$ (non-negative real). Then one can write the LP relaxation for maximum weight perfect matching as follows
$$
\text{maximize}~~\sum_{e\in E} w_e x_e
\\
\text{subject to}~~\sum_{e\in E: v\in e}x_e=1\text{ for all }v\in V
\\
0\le x_{e}\le 1\text{ for }e\in E.
$$
In the corresponding Integer Program $x_e$ is a binary variable s.t.
$$
x_e =
\begin{cases}
1 \text{ if } e \text{ is in the perfect matching}\\
0 \text{ otherwise}
\end{cases}
$$
I am unable to come up with an example where given $G$ has a perfect matching, the LP does not have an all integral optimal solution $x_e^{\text{*}}$. I tried taking small examples with odd length cycles, though there was a fractional optimal for the LP, there was an all integral optimal as well (in the examples I took).
I am aware that for bipartite graphs if the LP is feasible, then there always exists an all integral optimal for the LP. Does it hold for general graphs as well? If not I would appreciate hints so I can come up with such an example.
Comment: @Dmitry There is equality because I want perfect matching ie. each vertex should be incident to exactly one edge in the matching. For a triangle, perfect matching does not exist. I want an example of a graph where I know a perfect matching exists and the LP relaxation does not have an all integral optimal
Answer:
AB, CD, EF  is the unique perfect matching
Assigning $x_e = 0.5$ to all edges except CD gives the optimal LP solution.
Answer: Consider the graph consisting of two triangles $123,456$ connected by an edge $34$. The graph has a unique perfect matching $12,34,56$. Give the edges of the triangles weight $1$, and the edge $34$ weight $\epsilon$. The maximum weight perfect matching has weight $2+\epsilon$. Conversely, the fractional matching giving a weight of $1/2$ to each edge of each triangle has weight $3$.
Comment: I'm amazed how frequently it happens that there is a question which nobody touches for hour(s), and then several people post almost the same solution almost simultaneously.


Newly created objects linked by default

Question: When I create several objects, each time I try to work on a particular object, the rest of them are affected directly with any changes I make with the object I'm working on. Grouped by default. I clearly see that when I click to select on object, the rest of them are highlighted as well. How do I unlink this connection?
Comment: The problem is - you are adding objects in Edit Mode instead of Object Mode!
Answer: The picture is rather limited in regards of information (especially which mode it is in), so here a little info to ground my answer on:
If you have more then one object selected in object mode, the last selected one is brighter while all other selected ones are darker, if you then go in edit mode, they will all have the same color. Object mode can look like that picture in wire-frame mode.
Since they are in the same color, i would guess that you have those objects added while in edit mode and thus all are part of the same object, means if you select one of them in object mode all parts are selected. They are kinda joined, but only as in the meshes are under the same object. If you go in edit mode (i'd suggest vertex mode) and select all by pressing "a", you can then press "p" for the separate function and chose "By Loose Parts".
That way your meshes will be separated and each gets to be under its own object, means then you can edit them separately.

Newly created objects linked by default


Sigma 14.16 STS screen barely visible

Question: Around 4 months ago, I bought a Sigma 14.16 STS computer for my bike. I rode around 2500 km since then. Everything work perfectly until yesterday, when the computer just (almost) stopped displaying. What previously was a normal display, now has a couple of lines which change when pressing buttons, indicating that something is happening there and the computer itself works, but I still can't see anything. The thing was never put into extreme conditions (never colder than -8, never hotter than +20), I didn't try to drown it (even though it is waterproof and I used it in rain), didn't smash it against the ground (it never fell). Just the screen started malfunctioning. Anyone else ever had such a problem? What could be a fix?
Comment: I'm voting to close this question as off-topic because we are not Sigma's tech support.
Comment: It sounds like your unit was defective or you broke it somehow. You need to talk to Sigma's tech support; I don't think there's anything we can do for you, here.
Comment: Thank you. Yes, I tried switching to a new battery (2 new ones, for great measure). Neither worked.
Comment: Does it have a replaceable disposable battery?  like coin cells or an AAA cell?  If so try replacing it.   After a quick google, your unit has a rechargeable battery inside.   Leaving for generic advise but not applicable to you, sorry.
Answer: Several reason come to my mind:

The temperature at which you were using it. LCD displays get notoriously slow at low temperatures. You mention -8°, was it right then when this happened? Things should go back to normal at room temperature. The computer will still be working normally but the display literally freezes. The phenomenon is well known to people who own an early LCD wristwatch. They became unreadable in the cold.

At low temperatures, the battery either 3V lithium CR-type cell or Li-ion rechargeable slow down because of chemistry slowing.
If the battery is a CR-cell it might be reaching the end of its life. Your device may be new but the battery was already inside for a while when you bought the computer or the cell is faulty.Try replacing the battery.

But then since your device is quite new I'd advise you to take it back to shop who sold it to you as warranty is still applicable.
Comment: I accepted this as an answer since I guess it's a best one that can be given, given the generic nature of the question (unless someone had this exact same problem). In fact, the display seems to be getting better. Berhaps it will restore itselfs in a couple of days. I'm trying to heat the thing up to 30 degrees Celsius and it looks like it has some moisture inside - the vapor covers the inside of the screen. Perhaps it will recover itself, but I ordered a new one nonetheless. The device broke at around 0-2 degrees Celsius, not in -8.
Comment: @Zloj sounds like you should absolutely get a warranty replacement.  If its rated to be waterproof and isn't then that's a failing right there.

Sigma 14.16 STS screen barely visible


What does booting in to Windows in safe mode do?

Question: How is booting in to Windows in safe mode different from a normal boot?
Answer: My understanding is that it loads only the minimum drivers/settings needed for a very basic windows boot.  There are other options though such as starting with networking support (adding more drivers and settings to the boot), or the command prompt as as shell instead of Explorer.
Safe mode helps you troubleshoot a windows installation with bad driver and/or configuration settings.
Comment: There is also an option where it ask you before starting any service.
Comment: It also loads a low screen resolution, which is helpful if you install the wrong video driver and normal mode shows a black window.  This gives you a chance to rollback the driver/setting.
Answer: L0C0B0X is correct. Here's more info:
In Windows, what is Safe Mode used for and why?
Comment: Love the Gate's picture on that link, lol
Answer: In Windows XP, Safe Mode "uses a minimal set of device drivers and services to start Windows" (KB315222).  Importantly, no network drivers are loaded, and Microsoft's own vga.sys display adapter driver is used instead of the one that is designed for your hardware by its manufacturer.  This can get you out of a situation where you set display properties incorrectly causing your display adapter not to work.
See the following Microsoft Help and Support web page for more information about Windows XP's Safe Mode and its variations:  http://support.microsoft.com/kb/315222.
This Microsoft TechNet article has more detail about boot options as implemented in Windows 2000:  http://technet.microsoft.com/en-us/library/cc976736.aspx.
Raymond Chen wrote an column in the July 2007 issue of TechNet Magazine describing the behavior of Safe Mode in Windows 95:  http://technet.microsoft.com/en-us/magazine/cc138008.aspx.
Answer: The basic idea is to allow starting Windows with a minimal configuration of driver software and advanced settings in order to troubleshoot problems which make a Windows installation unusable (unstable drivers, problems with auto-starting software ...)
In "safe mode" just basic graphics drivers are loaded, enough to display the user interface in a low resolution, access to drives and Windows configuration, and very little else.


Infection of urinary tract if the pH of urine is made alkaline

Question: It is very well known that drugs like phenobarbiton,morphine are unionized, lipid soluble.So,in case if there is toxicity due to these drugs,the only way to save the patient is make the pH of urine alkaline and thus facilitating its excretion.But,the normal pH of the urine is acidic which protects the person from various urinary tract infections,if the pH is made alkaline is there a increased for the patient to have urinary tract infections?
Answer: There is a huge misconception here.  Morphine overdose is treated with Narcan (naloxone).  Phenobarbiton overdose is treated with artificial respiration (in extreme cases), blood pressure medication, and management of low heart rate.  The concept of lowering the pH of the urine to increase a drug excretion is (to my knowledge) never used in emergency settings.  Dialysis, which filters the blood, would be used to 'clean' the blood of toxins.  Think about it.  Time is life, and changing the composition of your fluids would take a lifetime compared to the implemented measures in emergency rooms.  You body has an extremely sensitive acid-base balance.  You do not want to try to increase or decrease the pH of your bodily fluids.


Can you mix brands?

Question: Can you mix string brands if they're in the same gauge? I have Ernie Ball strings and the 'A' string broke. Was wondering if i could Replace with a fender string of the same gauge?
Comment: Even though there are many string *brands* available, they are all made by only a few different manufacturers and just re-labeled, so it's entirely possible that Fender strings and Ernie Ball are actually the same thing. I'm pretty sure Ernie Ball and GHS are just two different labels of strings made at the same factory.
Comment: It won't do anything bad to the guitar. The tone may be different. But other than that if the gauge is the same I don't see why you couldn't.
Comment: Why not? You can even put bass strings on a plain guitar, as was done by Todd Rittman of [U.S. Maple](https://www.discogs.com/artist/135321-US-Maple).
Comment: Hmmm. Maybe I'm wrong. Ernie Ball strings were *originally* just custom gauge sets ordered from an existing string manufacturer and repackaged by Ernie Ball himself, but now it appears they have their own factory. Maybe that story is why people still to this day think there are only a few manufacturers that provide many labels. I found an anecdote on another forum from someone who has toured the fender string factory in Mexico, so perhaps those are their own brand. Also it seems like the raw wire used to make strings is only made by one or two companies.
Comment: No, you absolutely cannot. If you try to do that, the guitar police will burst through your windows and take you to jail.
Answer: There is no fundamental reason to use a single brand or even a single weight from one brand for all strings.  Granted you may find it easier to maintain an even sound level and strum/pick force if all strings are in the same weight class, but especially for acoustic guitars, you might find that swapping in one or two different weights improves the tone balance.
By way of comparison, many cellists use different brands and weights for the upper two strings vs. the lower two.
Comment: To echo your comments on cellists, my brother is a violin and mixes and matches all four strings from different sets and manufacturers. It is governed by the music he plays and how his violin is voiced. As a matter of personal taste he doesn't want four balanced strings and likes achieving a different timbre from each.

Can you mix brands?


How can I search multiple sites in a site collection (but not ALL of them)?

Question: I want to display a list of posts in a Content By Search web part. I only want posts from sites within the site collection that were created with my custom web template. Is this possible? I was thinking that I could filter based on a custom property in the SPWeb, but everything I'm seeing seems to indicate I can only search based on the metadata of the posts themselves.
Answer: With standard SP form I guess it's not possible. But you could build your own search form...

add a search results webpart.
edit webpart
click "Change query"
To get the search input from user choose "Value of a field on the page" as filter.
additionaly you can what ever filter you want here


What are the scriptures that describe Lord Shiva?

Question: I am interested to learn more about Shiva.

What are the Puranas to follow?
Apart from Puranas, are there other works which are authoritative and talk about Shiva?
Are there any epics which have Maheshwara as the core subject?
Comment: Shiva Purana & Linga Purana mainly. Also study the Srimad Bhagavatam.
Answer: The story of Shiva is as the name suggests covered in detail in Srimad Shiva Purana. Srimad Bhagavad Mahapurana also entails various leelas of Shiva. Srimad Devi Bhagavatam covers episodes of Shiva's glory relevant to Devi - Sati, Parvati, Kali. Linga Purana is also detailed narration Shiva and his glories and why we worship him as a linga. [This aspect is also covered in Shiva Purana]. Kalika Purana the story of Kali Maa and Nandi Purana the story of Nandi may also be  read.
There are also episodes of Shiva covered in Srimad Valmiki Ramayana and Srimad Mahabharata but most information is available from the first three puranas mentioned above.
This list may not be exhaustive, and is to the best of knowledge.   In case there are other scriptures, the same may be added to this list by the learned readers who can edit the answer.
Answer: There are many parvas (parts) of mahabharata which describes a lot about Lord Shiva. Like - Anushashan parva, Shanti parva, Vana parva, Drona parva, Karna parva & Harivamsa parva etc.


Does this table structure have an specific name?

Question: I'd like to know if this table structure has a particular name. How can I determine the tendency for 2017-09?
Answer: It has a number of possible names; such structure occurs in numerous contexts.
From the labels, you might refer to it as age-period-cohort data though such data aren't always (or perhaps even usually) given in that particular arrangement. (In your triangle, the periods are the diagonals running in this direction $.\cdot ^{{\:\cdot}}$ (cohorts are labelled and the ages are marked M1,M2,...)
In general insurance (property & casualty insurance) incremental claims (loss) triangles take just the form you have (though they're often cumulated by practitioners, it's really the incremental payments that are observed).
The same data structure is seen in the aids reporting data (e.g. see Davison & Hinkley's book on bootstrapping where it's presented in just this way)
Similar data can be found in other contexts.
While trends can occur in all three directions, because period = age + cohort, the three directions can't be modelled independently -- some constraints must be imposed.

You'll need to formulate a suitable model for your data; this should be informed by subject matter expertise (which we can't supply) as well as an understanding of the impact of the APC structure -- that linear trends in any of the three directions impact the others because of that connection between them..


Can Females Songbirds Have Male Plumage?

Question: Male birds are colorful for courtship displays, females are dull for camouflage. But, is written in a website somewhere that sometimes, when females birds are sterile, they grow male plumage due to male's feathers being a dormant gene (or something like that, sorry, I'm no professional). Is true? Can it happen? If so, how came? (and I lost the website's link, so I can't post it here, sorry again)
Comment: Please would you add a link to the website that you mentioned? That would be useful.
Answer: I don't have a link to a reference, but I was told by an ornithologist last week that in the UK, female blackbirds (usually brown plumage and brown beak) can sometimes change to more resemble males later in their lives (black plumage and orange beak).
Comment: Unfortunately, anecdotal references are not acceptable even if they come from an expert. Unless there is good statistical evidence, we cannot be sure. It would be super good if you can contact the ornithologist and ask them for a reference.


Must OK only be written in capital letters?

Question: Whenever I write ok the spell checkers underline it with a red line and suggest that I should OK. Not even Ok works. Why is that?
Comment: It's a bug in your spellchecker. Just add the word to your dict list.
Comment: @tchrist well its in Gmail. So its not my spell checker
Comment: If its gmail, that's most likely your web browser doing the spellcheck, not Google.
Comment: @tchrist: Since this is english.SE, I'll be that guy...It's not a bug when a word isn't in the list, and in this case, it might even be absent for a reason. See [the answer on the original](http://english.stackexchange.com/a/25646/58114), and upvote it!
Answer: OK is an abbreviation. This is what Oxford online dict says about its origin:

mid 19th century (originally US): probably an abbreviation of orl
  korrect, humorous form of all correct, popularized as a slogan during
  President Van Buren's re-election campaign of 1840 in the US; his
  nickname Old Kinderhook (derived from his birthplace) provided the
  initials

Now, let us look at this style guide about capitalization (Guardian Style Guide):

Use all capitals if an abbreviation is pronounced as the individual
  letters: BBC, VAT, etc; if it is an acronym (pronounced as a word)
  spell out with initial capital, eg Nasa, Nato, unless it can be
  considered to have entered the language as an everyday word, such as
  awol, laser and, more recently, asbo, pin number and sim card. Note
  that pdf and plc are lowercase.

Here is another style guide that suggests:

Pronounceable abbreviations Abbreviations that can be pronounced are
  usually acronyms, ie, words formed from or based on the initial
  letters or syllables of other words, such as radar, NATO, UNESCO.
  These are not normally preceded by the definite article.

But then, different office suites (MS Office, Libre Office, Lotus, etc) imply these rules differently. MS Office accepts both Ok and OK.
Answer: OK is Ok, and Ok is OK.
Oh, also Oklahoma is OK. That's its USA postal code, so it's possible that your spell-checker is agnostic on the subject, and just thinks you are trying to use the state of Oklahoma in an address.
I upvoted @camelbrush's answer because it provides a good explanation of the logic behind why some folks prefer to capitalize both letters. However, nobody is really sure where this word came from. Wikipedia has a table of around 30 of the more popular theories (from 13 different languages).
Realistically one just has to accept that both are in common use, and neither is provably "wrong". If the uncertainty really bugs you, just use the word "Okay" instead.
Comment: [Here's a theory that "ok" and "Ok" are not OK](http://english.stackexchange.com/a/25646/58114). +1 for the link to Wikipedia's proposed etymologies though! Too much false certainty going around on this question.
Comment: Here are a few other theories : http://www.thefictiondesk.com/blog/ok-or-okay/
Comment: I think it is problematic that there are two different accepted answers to this question on these boards (as Nick Stauner remarks, the question that this one is marked as a duplicate of, has an accepted answer saying that "OK" is the only valid spelling). I am inclined to disagree with T.E.D.: Although there are competing theories as to the origin of "OK", most (or all?) of them agree that it is an initialism, in which case all style guides seem to agree it should be uppercase. The only argument for "ok" is the descriptivist one: People do use it.
Comment: @Nagel - Not true. Of the three theories that Wikipedia bothered to explain out on their main Okay page (helpfully liked above), **only one** is an abbreviation. Not that I think that matters much. The question is about practice, not history. In practice, there is no authoritative answer, and both can be (and are) used.
Comment: @Nagel - Oh, and as for there being two "disagreeing" answers on supposedly "exact duplicate" questions, that's perhaps at least partially because the questions aren't in fact exact duplicates. This question is asking about capitalization, while the other was asking if there was any difference in meaning between the various forms found in the wild. The problem there IMHO is with folks who are overanxious to close questions, not with either answer. God save us all from the chaos that will ensue when some helpful person decides to merge the answers in these 2 supposedly "identical" questions.
Answer: The word is usually written OK or okay as it is a verbalization of the letters O and K, and that is simply the accepted spelling.
If I were to read ok or Ok somewhere, I would think it a misspelling of auk.
Comment: If **I** were to read *ok* or *Ok* somewhere, I would **certainly not** think it a misspelling of *auk*! I would think it meant *OK*.
Comment: @GEdgar In lowercase? At best, a typo for *oak*.
Comment: I might think of Oklahoma.
Comment: i wonder why the down vote? cause of suggesting auk?


Input line by line from an input file and tokenize using strtok() and the output into an output file

Question: What I am trying to do is to input a file LINE BY LINE and tokenize and output into an output file.What I have been able to do is input the first line in the file but my problem is that i am unable to input the next line to tokenize so that it could be saved as a second line in the output file,this is what i could do so far fro inputing the first line in the file.
#include <iostream>
#include<string>    //string library
#include<fstream>    //I/O stream input and output library

using namespace std;
const int MAX=300;    //intialization a constant called MAX for line length
int main()
{
   ifstream in;     //delcraing instream
   ofstream out;    //declaring outstream

   char oneline[MAX];   //declaring character called oneline with a length MAX

   in.open("infile.txt");  //open instream
   out.open("outfile.txt");  //opens outstream
   while(in)
   {

    in.getline(oneline,MAX); //get first line in instream

    char *ptr;      //Declaring a character pointer
    ptr = strtok(oneline," ,");
    //pointer scans first token in line and removes any delimiters

  while(ptr!=NULL)
   {

    out<<ptr<<" ";    //outputs file into copy file
    ptr=strtok(NULL," ,");
    //pointer moves to second token after first scan is over
   }

   }
   in.close();      //closes in file
   out.close();      //closes out file

   return 0;
}

Answer: The C++ String Toolkit Library (StrTk) has the following solution to your problem:
#include <iostream>
#include <string>
#include <deque>
#include "strtk.hpp"

int main()
{
   std::deque<std::string> word_list;
   strtk::for_each_line("data.txt",
                        [&word_list](const std::string& line)
                        {
                           const std::string delimiters = "\t\r\n ,,.;:'\""
                                                          "!@#$%^&*_-=+`~/\\"
                                                          "()[]{}<>";
                           strtk::parse(line,delimiters,word_list);
                        });

   std::cout << strtk::join(" ",word_list) << std::endl;

   return 0;
}

More examples can be found Here
Answer: You are using C runtime library when C++ makes this neater.
Code to do this in C++:
ifstream in;     //delcraing instream
ofstream out;    //declaring outstream

string oneline;

in.open("infile.txt");  //open instream
out.open("outfile.txt");  //opens outstream
while(getline(in, oneline))
{
    size_t begin(0);
    size_t end;
    do
    {
        end = oneline.find_first_of(" ,", begin);

        //outputs file into copy file
        out << oneline.substr(begin,
                    (end == string::npos ? oneline.size() : end) - begin) << ' ';

        begin = end+1;
        //pointer moves to second token after first scan is over
    }
    while (end != string::npos);
}

in.close();      //closes in file
out.close();      //closes out file

Input:

a,b c
de fg,hijklmn

Output:

a b c de fg hijklmn

If you want newlines, add out << endl; at the appropriate point.


completing a primitive integer vector into an integer matrix of determinant 1

Question: This is probably well known in algebraic number theory, in particular Minkowski lattice theory, but I am given an integer vector of dimension $n$ whose components are relatively prime, meaning there is an integer linear combination of them that equals 1. Is it true that I can always find $n-1$ other integer vectors such that they form an element of $SL(n, \mathbb{Z})$? I tried to think in terms of cofactor expansion of determinant, but that was only useful for $n=2$. Thinking geometrically also bore no fruit. Thanks!
Answer: HINT: This is a particular case of Smith normal form theorem.
Comment: Thanks for the hint. With further help of TedShifrin I got it finally. So we apply the Smith normal form to a n x 1 matrix, using product of elementary matrices P and Q, which both have determinant +/-1. Then $P'Q'$ would give the desired extension.
Answer: You can find the construction of such a basis in M. Newman's book "Integral Matrices". It's Theorem II.$1$ on Page 13.


Arcobjects: how do I find if a line intersects a polygon?

Question: I have one closed Polyline: "rectangle" and an open Polyline: "line".
Both Polylines may be Z aware.
What is the best way to find if the "line" intersects the "rectangle" in the XY plane?
That is I want a 2D (XY) test for intersection. I do not need the actual coordinates of any intersection(s).
Comment: You need to intersect then and check the output. If they intersect you will get some output, otherwise you will get a null geometry.
Answer: Exemple in VB.NET:
<code>Dim Rel As IRelationalOperator = CType(MyPolygon, IRelationalOperator)
Return Rel.Disjoint(MyPolyline)
</code>
I suggest not using ITopologicalOperator.Intersect, because as the ESRI doc says:

Since ArcGIS 9.2, Intersect has a larger cost - it takes longer to run
  the method.  Therefore, it is a better approach to test if the two
  geometries are disjoint before calling Intersect.


Unity3D: Convert all game objects to same size irrespective of it's scale

Question: Suppose I have a reference GameObject, Cube, with scale (1,1,1). There is another GameObject with scale (1,1,1), but the size is 3 times bigger than the Cube. How do I dynamically change the scale of the Game objects to fit the size of the Cube?
Comment: Is something like renderer.bounds.size good enough for you?
Comment: yeah, that's good! so should I keep reducing the scale such that `renderer.bounds.size` is equal to the cube?
Comment: You should be able to calculate how much bigger/ smaller the second object is. Get the volumen from the reference object and the new object, divide them by each other and multiply your scale by the result. Should scale your second GO to a matching size.
Answer: Untested, and completely from memory, but something kind of along these lines should work. I'll test it tonight when I have access to Unity.
<code>//scales all GameObjects in goResizeList to have the same size as the referenceGO.
public void resizeAll(List<GameObject> goResizeList, GameObject referenceGO){
  Vector3 refSize = referenceGo.renderer.bounds.size;

  foreach(GameObject go in goResizeList){
     float resizeX = refSize.x / go.renderer.bounds.size.x;
     float resizeY = refSize.y / go.renderer.bounds.size.y;
     float resizeZ = refSize.z / go.renderer.bounds.size.z;

     resizeX *= go.transform.localScale.x;
     resizeY *= go.transform.localScale.y;
     resizeZ *= go.transform.localScale.z;

     go.transform.localScale = new Vector3(resizeX, resizeY, resizeZ);
  }

}
</code>


Are black holes really black?

Question: I don't think that black holes are really black as they are the only ones who have the capacity to bend light. At the centre of the black hole the laws of physics are totally defied, black holes appear black as space is black in colour.
Comment: It would be great if you [edit]]ed this question to say what research you have already done.  For example, have you read the black hole page on Wikipedia.
Comment: Welcome on the Astronomy SE! Also a lens can bend light, although it does with an entirely different effect.
Comment: @peterh bending of light doesn't mean just changing the direction, black holes absorbs light completely where there is no chance for light to escape so there is no chance of reflection of light in black hole so black holes appear black
Answer: Black holes really look black.
Things look black because they don't reflect or emit light. A black hole is a region of spacetime which light can enter, but can't leave. Black holes don't reflect or emit light, so they look black.
Black holes are not the only things that bend light. Every object with mass bends light. Black holes bend light more than other objects because there is so much mass in such a small region.
Black holes don't have a surface, so they aren't black for the same reason that soot is black.  They are black because they don't reflect or emit light. Space also appears black because empty space does not refect or emit light.
"At the centre" is a difficult idea for black holes, because space and time are bent so much near the black hole that the centre becomes a "when" not a "where".  The laws of physics aren't defied, but we don't know what the laws are at the time in the centre of a black hole.
(Hawking radiation is predicted to be emitted by black holes. This makes black holes emit light, but for a large black hole Hawking radiation is very low energy and very dim.  It is theoretical, it has never been detected, but the theory is very strong and well supported)
(Around the outside of the black hole matter may be falling in. This matter gets very very hot, and so shines very brightly. This means we can see where a black hole is, because we can see the matter that is falling into the black hole)

Are black holes really black?


How can I integrate Google Suggest with Magento address?

Question: I searched after some ideas how to achieve this and I couldn't find any hint. I know that there is a module which uses this but I am not interested to buy it only for this option.
The link with the module
http://www.magestore.com/magento-one-step-checkout-extension.html
Answer: @fbrnc and the guys from AOE made up an extension called Aoe_AddressAutoComplete which does exactly that and which is on GitHub. Though they say it is highly experimental, it may be a good source for you to have a look how they did it. Ideally, if you have any issues with the extension, you can fix the code and send them a pull request.
Answer: Take a look at the google api for Autocomplete for Addresses and Search Terms
In your onepage checkout address template you would need to slightly modify Autocomplete for address forms (live example)
Answer: If someone is looking for a free solution three years later. I found this module on Github. It works great for Magento 1.8.x and 1.9.x and I've been easily able to modify it for a custom checkout.
Answer: In order to integrate Google Suggest with Magento address, you don't need to buy the One step checkout extension but a separate Google Address Autocomplete extension. There are some free and paid ones.
Another similar extension that provides the autocomplete function when the customers type their addresses is this Magento 2 Address Autocomplete. Different from the Google Suggest extensions, it doesn't use Google API and you can import the addresses into your database. In the frontend, when the users enter one of the shipping fields (city, state/province, subdistrict, zip/postal code), it will immediately suggest some related addresses taken from the database, and then once an address is selected, all of the remaining fields will be auto-filled instantly.


Multiple #'s on Note 3

Question: Can the Note 3 have more than 1 number associated with the same phone? Someone gave me their # and then another #. They said it was the same phone.
Answer: It seems there is a Galaxy Note 3 with dual SIM support.
Answer: Geff already showed one easy explanation: Dual-SIM devices.
But never mind how many SIMs: I have a single SIM phone which has two numbers assigned. Well, even 3 now. I've got

the usual mobile number, plus
my provider assigned me a landline number, to which I
forward calls from another landline number.

Number 3 clearly shows how it's possible for everybody. Though technically I have to admit, I assume that even #2 is nothing but a call-forward on the provider's end. So it all comes up to your definition of "number assignment".

Multiple #'s on Note 3


D.va's movement speed comparison

Question: Does Dva move faster while constantly pressing left click (regular shots) while moving,
or just holding down the left click and moving? or is it the same movement speed?
Answer: D.va moves faster if you spam left click shots as opposed to holding them down, but you will suffer a huge loss in potential DPS as a result.
Comment: Since her damage drops off so sharply with distance, and I assume you're moving toward your target, getting closer to them more quickly will increase the damage your shots do. That will compete with the loss in damage due to shooting less.

D.va's movement speed comparison


Can I Implement a PLL on an Arduino?

Question: Is it possible to create a system like a PLL using an Arduino?
I ask this because there are some parts in the PLL system, such as: phase detector, VCO, divider, and I don't know how to make for each part in Arduino board.
Comment: An Uno does not use an ATtiny, so no.  You may be able to build a frequency locked loop in software, but right now the major problem with your question is that you don't specify the details of your goal
Comment: The ATTinys have a build in PLL.
Comment: thanks gerben, so if i use aduino uno all i have to do to make a PLL is just to coding it right??
Comment: Uno uses an ATMega328. You can e.g. use a bare ATTiny85 chip, or a board based on that same chip, like a Trinket, or Digispark. (There are other ATTinys beside the 85, but that one is the most popular).
Comment: thanks again greben, i forget that one point, this is for my final project my goal is to create a signal (pll output) from the reference signal that come from function generator.
my lecturer said the reference signal i have to give is following the working frekuency and amplitude of arduino uno. so it's doesn't need special req. right?
Answer: A PLL is a very complex device which is not something that can easily be created purely in code.
Many microcontrollers include a PLL as part of their oscillator systemm which allows them to run internally at a higher speed than their external crystal.  This is not a programmable peripheral that you can use for your own things, but an integral part of the workings of the microcontroller.
While it may be possible to write one in software the results would be very somewhat limited. The best you could hope for is to use timers to measure an incoming frequency and use the results to output another frequency through some means, maybe PWM.
To create a real PLL you would be best off using either a dedicated PLL chip (which you can buy off the shelf) or use some form of programmable logic like a CPLD that has a built in PLL block.
Some microcontrollers, most notably the Cypress PSoC range, have programmable logic blocks built in that may be more suited to your task than an Arduino.
A typical digital PLL looks something like this:

Implementing all that in code would be both tricky and somewhat slow on a little 8-bit MCU with no floating point support.  However, the basic principal of what a PLL can be summarised in one simple sentence:

The frequency coming in determines the frequency going out.

The PLL, or Phase Locked Loop is just one method of achieving that desired result.
Another method, which is not using any form of PLL, is purely algorithmic and consists of just three things:

Three simple blocks, all of which the Arduino is, to a certain extent, capable of performing.
The first block, the Frequency Detector, works out what the frequency of the incoming signal is.  That could either be by counting the number of pulses that arrive over a certain time frame, or measuring the time between successive pulses.  Which method you use (Frequency Counting or Frequency Measuring) is really down to what frequency ranges you are using.  Frequency Counting is better for higher frequencies, whereas Frequency Measuring is better for low frequencies.  There are many examples on the web of how to do both of those using timers on the Arduino.
The Decision Making is basically working out what your output frequency wants to be according to your input frequency.  This could be as simple as "Output = input * 2", for instance, or something more complex like "Between these frequencies I want to output this frequency, between these frequencies this other frequency, etc".  It's entirely up to you.
The third block just takes the decided-upon output frequency and generates it.  That could be done using the hardware PWM generation of the Arduino.
All this, though, will be limited to relatively low frequencies (tens of kHz maximum really) though with clever coding you could push it up slightly higher.
One thing that really makes this method differ from a PLL is that you don't get the "PL" portion of it - that is, the phase of the incoming frequency is lost, and the output frequency is running entirely with its own phase.  There is little or nothing you can do to synchronise the phases of the input and output like you get with a full PLL.
Comment: thanks majenko, sadly i already propose this title for my final project so i have to build this system using arduino. and i think what i aiming is that complex. do you have any idea?
Comment: thanks @majenko, i'll consider it by using arduino due just like jack said.
and i'll be concern about the output that arduino gives..
Comment: Addendum: Use an output oscillator with reset function. Detect the "reset point" of the input waveform. (The Arduino supports interrupts, for example)
Comment: thanks for that @MickLH.. i've already considered by using arduino, despite it might be expensive but i has already propose it..
Comment: For countable frequencies, you can easily get the PL phase information by using sort of a Bresenham algorithm counter, incrementing by a quantity for each output pulse, and decrementing by a quantity for each input pulse. (eg, for a 100Hz output from a 1PPS,  `bresenham++` each output pulse, and on each PPS `bresenham-=100;` and adjust the output interval.  When they are in phase, the count is stable.    If they are out of phase, the Bresenham count would tell you which way and by how far, and you could use that phase information for decision making.
Answer: There are two types of PLLs, hardware PLLs and software PLLs. Majenko has already addressed hardware PLLs so I will leave you to his answer for that.
Software PLLs perform the same function as regular hardware PLLs, but with code, and as a result are constrained by the clock speed and sample rate of the controller they are running on. Usually this means you are limited to sub MHz frequencies. The math and computation necessary to perform this is quite complicated, and I do not expect you would get particularly good performance out of your standard Arduino controller, as all of them lack a floating point unit to perform these types of computations.
If you were to still try and attempt this you would have to do it using integer math only. The faster the CPU, the higher the frequency it will be able to lock on to. The fastest Arduino available today is the Arduino Due. Aside from being fast, the Due can perform 32-bit arithmetic in a single cycle, which should be handy. The frequency limit will be dictated by how many cycles all of your calculations take.
Comment: thanks jake, that's all i need.
i only need a low frequencies in range of KHz, and the amplitudes is follow the maximum input voltage of arduino right?
and which arduino can you suggest?
Comment: I've added to my answer a few extra notes on attempting this. All I can say is: Good Luck! Software PLLs are tricky; there are a lot of resources out there about how to do it theoretically, but very few on real world implementations of them.
Comment: thanks a lot jake, well i have a lot of work right.. maybe i'll ask you more about it while i'm working on it could i?
Answer: You can absolutely make a PLL using an ATMega microcontroller, and I have made one myself using a ATTiny45. The way I did it is by setting the clock source to the internal RC oscillator, and using that as my VCO (or in this case, Numerically Controlled Oscillator). The internal oscillator can be tuned between 50% and 200% of its nominal frequency by adjusting the OSCCAL register, which can safely be done without stopping the processor. I used the ADC to read the input signal. For the phase detector I programmed the MCU to alternatively add, then subtract the ADC registers from an accumulator register. This is mathematically equivalent to multiplying the incoming signal by a square wave from the local oscillator, and integrating the result. After a fixed number of cycles, I checked to see if the accumulator was negative or positive. If its negative, I set OSCCAL to a "high frequency" which is definitely higher than the input signal. If its positive, I set it to a "low frequency", which is definitely too low. Of course this is a form of Bang–bang control, so its never stable per se, but I found works perfectly. Its much better than my attempts at a PID controller. Looking on my oscilloscope, the is almost no jitter visible between the input system and the internal RC clock, which I outputted on the CLKO pin by setting the appropriate fuse bits.
Although I used GCC and USBTinyISP, I see no reason why my system can't be implemented on Arduino. Setting the fuse bits will require a bit of work though, you can read more here:
http://forum.arduino.cc/index.php?topic=124879.0
If there is enough interest, I can add more detailed information to my answer.
Comment: Thanks for your answer @Misha and ya, i'm little bit interest with your detail. And first at all to implement pll using arduino, how can i used adc to read the input signal if it come from function generator for example?

Can I Implement a PLL on an Arduino?


My Minecraft Servers won't show up- Not Multiplayer or Singleplayer

Question: I play my mine craft on a Macbook Pro, Recently I had gotten it to work again, And saw my old servers. I played on a couple of them for awhile, But none had nothing much on them. I had a giant list of Multiplayer servers as that is all I played on. Recently, I signed on and realized that none of my Servers were there. I thought that maybe it was from me changing my username from chloe4068 to ScarletWolfGames, But even with the name change my servers were still there. I went to download an adventure map and Put it in the saves folder, In which, My old servers were still on. Well. My single player ones anyway. I thought my old servers would be back, I played again, They weren't there. Before I had played I had deleted copies of mine craft folders with the same things in them, well, same folders. I had then lost my servers, But seeing how they still exist but aren't in the game confuses me. Any help?
Comment: Single player servers? Are you talking about your savegames rather than servers perhaps?
Comment: Oh! Oh yeah! Forgot to add that onto there. Yes the folder I found was my saved games, I found my old servers while trying to download the Adventure Map, Which I had stated in the explanation.
Comment: what are servers and what is save-games? I need more info to answer this. I may know an answer, but I need you to edit it to where we can tell the difference in servers and single-player games.
Answer: The (multiplayer) servers are stored in the servers.bat file, which you might have deleted. Singleplayer worlds on the other hand are stored in the saves folder, which is in your case still there.
Comment: Isn't it `servers.dat`?