Is it ok to plant tomato plants in an old slightly rusty lawn cart?

Question: Is it ok to plant tomato plants in an old slightly rusty lawn cart used for pulling behind my lawnmower?
Answer: whenever I make a planter out of something like that: cart, wheelbarrow, etc... I get myself a glue-gun and line them with fabric first. However, that has less to do with any assumptions I am making about contaminating dirt and more to do with removing the dirt at a later point in time.
Answer: I would not use it. Old mowers spill oil, which could remain in the cart. You should also be sure that there were not lead (especially used during maintenance work). Acid on fertilizers could make it to release other metals and stuffs.
But you can check carefully how it is made, and which materials.  In any case it should be good for flowers. Maybe start with flowers, and if it remain inert, you may use it for (non-intensive) tomatoes.


Writing keylogger and viruses in python

Question: So recently I have been working on some projects one of them is keylogger and the second is SYNflood (both in python). I want to know if ,is it a good practice to use python language for such purposes? (Maybe you know from your own experience)
Comment: When you use C and other low level language you can create small size file.When you use other kind of programming language like python ,your final size of file is much bigger than others.Some cases, size of file is important.
Comment: You can use Python to send your shellcode, it's quick and easy to setup listening sockets and what not for keyloggers.  But your exploit code itself will most likely not be written in Python.
Comment: may explain please,why python isnt good for such purpuse? and suggest another language to do so?
Comment: The target computer must also have python installed for the keylogger to run. You can however ship python with your keylogger, but as @dgn said, the size will increase.
Comment: @YakovMor It really depends on what you want to do, but Python is an interpreted language.  You can create compiled Python, but to access a lot of the constructs in an operating system lower level languages provide APIs to make this easier.  You don't want to be doing system calls in Python.
Comment: Ok I understand . But what about  c++?
Answer: About writing tools like this SYNFlood, python is as good as any other language you feel comfortable with. There is an excellent book called "Violent Python" where you will learn to write security auditing tools and malwares. From network scanners, login bruteforcers, FastFlux behavior to mimicking botnet functionalities, you will learn a lot about them.
Writing malware in python can make your life easier (in a part) as it is very quick and easy to code. Python is really an uncommon choice for viruses and the like because it needs an installed interpreter to run. You may overcome that by turning the script into a windows executable using available tools (like py2exe), but that tends to produce big executables (maybe 5MB, depending on the imported modules) and as malware tend to survive on its subtlety, it may be spotted sooner than you expect, not only because of executable size but also memory footprints.
Compiled python scripts can be turned back to its script form with great ease, using modules like uncompyle2. Once it is found, that will allow the malware analyst to quickly know what it does, how it does, where the command and control servers are, etc., making it extremely fast to uncover your whole operation and reducing the effectiveness of your malware as AV vendors push your signature into their products.
On the other side, as someone said in this reddit post about a Bluecoat report (linked below), AV detection rate for scripted languages tend to be low, as many installers use them to deploy softwares.
Doing some more research, i heard about the Flame malware and according to the article, it was 20MB in size, including libraries, sqlite databases and all. So, size may not be "that great burden" after all...
Here is a report from the security company Bluecoat about a python malware that relates to the Hangover operation in 2013.
Most malware are written using C/C++/C#, VB, Assembly, .NET, etc., but that is not a law. These languages have advantages, but also does python. Everything depends on your goal. Balance what you want with what you need and take your shot with what feels the best option to fulfill them.

Writing keylogger and viruses in python


Energy bands. Bonding and antibonding orbitals

Question: In tight-binding wikipedia  article it is said that bonding and anti-bonding orbitals correspond to different $k$-values in a single energy band. At the same time in Cordona Fundamentals of Semiconductors book there is the following picture.

It says that bonding and anti-bonding orbitals correspond to different energy bands. Please help me understand this.
Comment: Simplistic pictures to explain electron energy levels in crystals are, well, simplistic. See, for example, https://physics.stackexchange.com/questions/386542/reorganization-of-energy-bands-beyond-a-very-low-lattice-constant/386608#386608
Answer: Simply, different orbitals correspond to different energy bands, whereas anti bonding and bonding orbitals correspond to the change in energy between lines that make up a band. For example, the p orbital band of a certain element (say silicon) may look different than the s band; that is, the distance/bandgap between certain bands - which represent certain orbitals - may differ due to the structure of the atom, as well as the bonding of the atom. Furthermore, the figure depicts silicon's atomic orbital, where the distance between the anti-bonding and bonding orbitals represents a change in energy states (delta E). Nevertheless, the k value which measures the energy and reactivity of electrons, which in this case refers to that of occupied orbitals because it is (+)k, corresponds to the wave mechanics of electrons as described by the Pullmans in their volume, "Quantum Biochemistry," so the difference in energy states does correspond to different k values that define donor-acceptor characteristics of a molecule. However, it may help to recall what the band both demonstrates and means; the band represents the continuum of individual energy states of electrons in a mole of an element or molecule, in which individual orbitals decrease in distance from each other as you increase the number of orbitals. Moreover, the band is important to understand because it indicates the general properties of an element or molecule, such as conductivity and even thermal properties.
Understanding the Molecular Orbital (MO) theory is the key to understanding bands and their intricacies. In MO theory, atomic orbitals combine to form molecular orbitals, and the antibond and bond states simply demonstrate different energy levels; this is where electrons, more accurately recognized as wave functions constructively (bond) and destructively (anti bond) interfere to form molecular orbitals - which defines the covalent bond - between constituent atoms; this distinction of bonding is also the 1st principle of Molecular Orbital (MO) theory. Additionally, the overlap between atomic orbitals directly corresponds to the change in energy between bonding and anti-bonding orbitals, where a large overlap correlates to a large change in energy in the molecular orbital. Furthermore, in determining MO configuration, the stability of a molecule (bond order) - as well as its overall structure - can be identified, which helps retain an accurate picture of the molecule and its fundamental properties as a whole.
Though, if you need more clarification or details, visit the MIT Solid State Chemistry playlist on YouTube; I referenced lectures 12-16.  Information related to the Pullman K is from Albert Szent-Gyorgyi's book, Bioelectronics.


What is a brief summary of the ECB's report on virtual currency?

Question: On 29th Oct 2012, the European Central Bank released this report on virtual currency.
What is a summary of its comments on Bitcoin?
Answer: In the ECB's view,  (Bitcoin) can be used by business (criminals), customers (fraudsters) and savers (money launderers) to perform legal (illegal) activities, but lets ignore it until volume reaches a level where comparison with sovereign currencies reflects negatively on our reputation. The public will then expect us to regulate such digital (rogue) systems (schemes).
Comment: Best answer in this stack exchange!
Answer: The ECB is a monopolistic institution: it holds a monopoly over the issuing of money on Europe. As a byproduct, any possible competitor is going to A) Be detained and its activity stopped B) Be criminalized or C) Be condemned. Since technology makes impossible to Government to take over Bitcoin, you can expect (C) for a long, long time.
If Bitcoin gets popular in the near future, because of the utter destruction of fiat currency governments are doing, you can even expect to be criminalized or highly taxed for being a bitcoin user.
Free and competitive money/currency is the nightmare of regulators (looters)


Is it healthy to exercise a muscle when it's still sore?

Question: Is it healthy or is it damaging to exercise a muscle while it's still sore from a previous workout?
Comment: You only ask about muscles, but don't forget that **also joints, tendons, and ligaments are subject to training -- with *possibly longer* supercompensation periods** than your muscles! Thus, if already your muscles show on-set fatigue, I would be wary to *not* overload the other structures, more so, if you happened to had been injured, say, in your tendons in the past.
Comment: Related (if not duplicate): http://fitness.stackexchange.com/questions/7443/should-i-exercise-when-my-muscles-are-aching
Answer: In general, training while sore is perfectly fine and usually beneficial, subject to a few caveats discussed below. Almost every serious athlete frequently trains while still a bit sore from the previous workout.

Image from the wikipedia article:
The first thing to understand is supercompensation: a short while after training, your muscles end up a bit stronger. If you train again during this period, your next supercompensation period will be slightly stronger again. Repeat this cycle with proper timing over and over again and you'll gain strength in the most efficient way possible. Wait too long and the muscle returns back to a "normal" state and strength gains are slowed.
The second thing to understand is that soreness has nothing to do with the effectiveness of your workout. It's more of a side effect, which is actually not well understood. Depending on your training level and workouts, you may still be sore even when your muscles are in the supercompensation period. If this happens, you just need to put up with it and train sufficiently hard to keep the gains coming.
BTW, this is also a reason why split routines - where you train each muscle once a week - are very inefficient for the vast majority of beginner & intermediate lifters. Your muscles hit the supercompensation period in far less than a week and have started to return to normal by the time you train again. In this respect, fully body routines 2-3 times per week are going to produce strength gains much faster.
Some caveats: if you are sore to the point that it interferes with the workout (ie, you can't do the motion correctly), then you won't gain much from exercise and are better off resting. A rule of thumb to determine this is to do a thorough warm-up: if everything loosens up and you feel ok, train on. If you are still stiff and it hurts to move, rest. If you are new to a certain type of exercise, soreness levels will be much higher, so the first few weeks may require skipping more workouts than normal (don't make it a habit though). Finally, more advanced lifters who are moving a lot of weight will take longer to recover, which will impact things like workout frequency and volume.
Comment: So, how can I tell when recovery ends and supercompensation begins?
Comment: @Samuel: there is no exact way to tell for yourself, but various studies and anecdotal evidence suggest ~48 hours is good enough for the average trainee/workout. In other words, unless you are moving HUGE weights/volume, working out the same muscles/motions 2-3 days per week on non-consecutive days tends to be ideal.
Comment: @samuelandrew This isn't the sort of thing you'll be able to "feel", this is about the underlying physiology. The general rule is 2-3 days for most muscles.
Comment: Yevgenly very good answer. +1000 for mentioning "split routines - where you train each muscle once a week - are very inefficient for the vast majority of beginner & intermediate lifters. "
Comment: @LulY Best source I've read on this stuff is in _Practical Programming for Strength Training_ by Mark Rippetoe and Lon Kilgore. They dive deep into these topics. See also my notes on this book on GoodReads: https://www.goodreads.com/review/show/198581058
Comment: Ok, thanks. What I've been doing is upper body one day, then lower body the next, then upper body, so on and so on. do you think that's okay?
Comment: Hard to say without knowing more about you and the routine. How long have you been lifting? What exercises? How many sets/reps? In general though, upper-lower-rest can be an effective 3 day scheme for most lifters.
Comment: @YevgeniyBrikman Okay, thanks. I reckon I fall into "most Lifters" more or less.
Comment: When are you out of beginner & intermediate category?
Comment: @Esqarrouth: You shouldn't *want* to be out of beginner and intermediate territory. Beginner routines are designed to give you the fastest gains possible, typically increasing the weight on the bar every single workout. The more advanced routines are slower, more complicated, and not as fun. So in a sense, that's one answer to your question: stick with a beginner routine as long as you possibly can. Only when you can no longer make progress at that rate should you do something more complicated.
Comment: @Esqarrouth: As a second answer to your question, and as a rough guide to where you are progress-wise, check out the weightlifting performance standards: http://www.exrx.net/Testing/WeightLifting/StrengthStandards.htm
Comment: Any source for "Depending on your training level and workouts, you may still be sore even when your muscles are in the supercompensation period"? This is the key point to the question
Answer: Your muscles need time to recover. Thats why you don't work on your arms every day for example.
Mon = arms
Tue = legs
Wed = back
 etc.
However, stretching and light workouts can actually help soreness and stiffness.
Truth about stretching
Importance & Dangers Of Stretching
I would say it isn't a good idea to do heavy training consecutively on the same muscle group.
sometimes when you're starting out a new exercise like a cardio routine your muscles can get sore because they're not used to being worked. In that case I would say that it would be just fine (with moderation).
Either way you need to let your muscles recover properly and it's a good idea to change up your routine day-to-day or to have a staggered schedule.
In any case, overworking can hurt your results.
Comment: -1 for a couple reasons: first, muscles do need time to recover, but a split routine like you listed isn't necessary. In fact, it's quite possible to train the same muscles/movements every day: see the routines of olympic weightlifters for reference. Second, while stretching is definitely useful to increase flexibility/mobility, it is not likely to reduce soreness. If anything, stretching is likely to create more microtears in muscles and *increase* soreness. It's still a great thing to do, but not as a recovery mechanism.
Comment: @md5sum as far as DOMS, you are correct no stretching is going to solve or prevent DOMS due to the definition of DOMS and I never said that. My statement was stretching can help stiffness and soreness and it does. I dont have a problem with DOMS because I'm careful and follow rules such as 'stagered workouts' and proper recovery times. Article abount DOMS: http://www.bodybuilding.com/fun/south127.htm
Comment: @Yevgeniy not all olympic weightlifters train every day - some take recovery very seriously and train shockingly infrequently. See trainees of Rogozhnkov, for example. I think the type of training matters - true strength training has enough rest and never to failure that soreness is never an issue. But lighter higher-rep training for mass is a different beast.
Comment: Stretching and light workouts have been shown to have little to no impact on delayed onset muscle soreness (DOMS). Stretching decreases your usable muscle strength, and has negligible impact on injury prevention.
Comment: @Greg: of course not all oly-lifters train every day and I'm certainly not advocating anyone does. But some do and do so successfully, so it serves well as a counterexample to the "don't work the same muscle every day" argument. My main point is that muscles adapt very well and will tolerate more than "bro-science" would have you believe.
Answer: Should you workout, my answer is an unequivocal yes, while I do not know the frequency of your workouts or the intensity. I workout each muscle type every 48 hours even if the muscles still ache. I have been doing this for many years and had no issues. Most trainers recommend it.
Working out often is great for building muscle and maintaining a routine is just as important even if you do not feel like you should. Do it.
In the gym this feeling is called DOMS (delayed onset muscle soreness), and is caused by muscle tearing brought on by your previous workout session. Its also a sign you had a good exerting workout.
You will not feel DOMS often, once you get used to your workouts or reach a plateau with your routine you will stop feeling the DOMS and its a sign you need to make the routine more challenging.
Comment: I would say for overall benefits you should CHANGE your game, not up it. I would say up your game if you were weight training but it seems like the OP is asking about general exercise.
Comment: While it's true that: "no pain, no gain" there's an optimum for when your body is super-imposed compared to before the workout and that's when you want to be working out that same muscles again. When that is varies between people, so the 48 hours might work for you but it might be something else for someone else
Comment: Ivo thats a good point but 24 rest period is the de-facto norm. If your muscles havent recovered then all your doing at that point is straining them and causing injury
Answer: Recover no matter what you do.  If you are not sure if it has been long enough, start with your warm ups. If you feel better while warming up, go ahead into your workout.
If you have been eating right and resting, then you should be o.k.
Comment: Is this your personal experience or can you back up your claims?


Is it possible to enable Code Folding in Xcode for Bash scripts?

Question: I work a lot with bash scripts and some of them can get pretty lengthy. Up until now, I've been using BBEdit as my editor of choice because of the way it handles locked files and permissions. But ... BBEdit doesn't support code folding. Xcode does, but it seems to only allow code folding in Obj-C and Swift. Is there any way to enable code folding for Bash scripts? If not, is there any app out there that can fold code in a bash script (preferably with syntax highlighting too)?
Answer: I haven't found a way to enable code folding for bash script in Xcode.
But here is an alternative: UltraEdit.
UE allows code folding for bash scripts after tweaking a file.
In the example below i have added
<code>/Open Fold Strings = "{" "if" "elif" "do"
/Close Fold Strings = "}" "elif" "fi" "done"
/Ignore Fold Strings = "echo"
</code>
to the file ~/Library/Application Support/UltraEdit/wordfiles/bash.uew
Depending on your needs you may add other strings of course.


Easiest method to backup my stock and Chrome favourites so I can access them on a new device?

Question: My Samsung Galaxy S III running Android 4.1 looks like it's going to die and I was wondering what's the quickest method to backup my Favourites from Chrome and stock so that I can copy them to a new device?  Note: I don't have PC access and I'd like to keep the folders.
Answer: For Chrome bookmarks the easiest way is to enable Chrome bookmark syncing via your Google account. If this hasn't been automatically done, you can find the option to log in to your google account from Chrome in Menu -> Settings -> Sign in to Chrome. After this, your bookmarks will be synced to the cloud and you can simply repeat the process on the new device. Note that this also works for the desktop and iOS versions, if you'll ever need them.
Answer: You could use a dedicated backup app such as Backup SMS, Contacts & Apps:

This is a Backup Manager / backup Assistant which lets you maintain backups of various things such as Contacts, SMS, Calendars, Bookmarks, Apps & Call logs. All of this can be kept safely in your email ID & on your external memory. Also helps transfer data from one phone to another.

(emphasis mine). The quote is from the app description, and as my emphasis shows, this should be perfectly fitting your needs.


Windows cloud instances for testing open-source project?

Question: I work with SCons (www.scons.org), the open-source build tool.  We do test-driven development, and we have a buildbot, but we're always short of Windows buildslaves.  We'd like (in a perfect world) a large collection with different python versions, different compilers, etc.  Is there any free or near-free cloud-based Windows instance we can use with buildbot?  I've looked at Azure and Amazon EC2 -- EC2 micro instances seem like our best bet at the moment, but I'm wondering if there's anything truly free as in beer for open-source project testing.  Anyone else doing anything like this with experience to share?
Answer: AWS Free Tier includes 750 hours of Linux or Windows Micro Instances each month for one year. To stay within the Free Tier, use only EC2 Micro instances and this is only for ONE year however with Windows Azure there is no Free instances besides 90 days FREE trial period. To answer your question directly Windows Azure Virtual machine instance are not FREE at however if you decided to choose XS (Extra Small) instances you pay almost the cost of 2 beer per month as shows below:

Price Calculator: https://www.windowsazure.com/en-us/pricing/calculator/?scenario=virtual-machines


Cart automatically empty after 2 hour

Question: I add the product in cart at 10:00 am then when i refresh the page at 12:00 pm i see cart is empty automatically .
I check the admin settings there are we set the time [ 31536000 ] in Persistence Lifetime (seconds)  which is almost 1 year .
In the admin Cookie Lifetime is also [ 31536000 ] .
In php.ini file [ session.gc_maxlifetime ] is also more then 2 hours .
But the cart is empty after hours .
I set 300 seconds then the cart empty after 5 min but if i set more then 31536000 or any other time which is more then 2 hours time then cart empty after 2 hours automatically .
I check the log files to look out for any error in logs but there are no errors in log files.
Could anyone suggest regarding this so i can proceed forward.
Answer: Try to check if there is a cron job or module that is affecting or maybe there is an issue with the caching mechanism in Magento, you may want to check your cache settings to make sure that they are configured correctly and the cache is not cleared prematurely.
Comment: Thanks , I already check the cache settings they are configured correctly and cache is cleared too , we have not any cron job which is related to this .

Cart automatically empty after 2 hour


Which is it: "1½ years old" or "1½ year old"?

Question: 1½ is not yet 2 or more, so which do we properly say: "1½ years old" or "1½ year old"?
Comment: Yet another numeric adjectival question. Yet another quantity-vs-quality question.
Comment: You can also say the child is **18 months old**. Alternatively,  **"He's one and a half"** would be understood perfectly (presumably one would already know the child's gender). I think the full written form is preferable, but there's no one to stop you from writing the number in digits: **"He's 1½ years old"** is also fine.
Answer: If the entry is part of a classification:

That kid is a one-and-a-half-year-old.

If the entry is describing the age of the person:

That kid is one and a half years old.

Both of these work, and work similarly for whole numbers:

That man is a 50-year-old [person].
That man is 50 years old.
Comment: It would come much more naturally to a native speaker to say not "That man is a 50-year-old" *[note also the hyphenation here]* but "That is a 50-year-old man"; similarly, not "That kid is a one-and-a-half-year-old today" *[a construction I have* never *heard anyone use when referring to half years as part of someone's age]*, but "That is a one-and-a-half-year-old kid" (omitting the 'today'), or more likely, "That kid is one and a half years old". You would only include 'today' if today happened to be the child's half birthday.


How to improve UX understanding efficiently?

Question: What do you think is the most efficient way to get an better understanding of general UX apart from just reading a lot books & blogs?
Comment: This is more of a discussion/opinion enticing question than an explicit answer. It would be better to ask this in chat.
Answer: I would say that a very efficient way is to learn by studying examples. Check books or blogs for lists of websites that have great UX and then dissect those websites.
ux.stackexchange has good UX in my opinion. You could start by dissecting this site. Right a concrete list of the components that demonstrate good UX and then do more research on the particular components you want to know more about.
For example, you could analyse their reward system. Those bronze, gold, and silver achievements make it fun for users and also align with the business goals of the website
Answer: User Experience is based on users, from personal experience I have gone to the people to ask them what needs to be refined to provide a better user experience. This can be conducted through testing and surveys. The Nielsen Norman Group is also a great resource dealing with UX research.


What technologies should we use to process terra bytes of data in real time?

Question: We have a website which generates MB/TB of data which needs to be mined. What technologies should we use to process terra bytes of data in real time ? Hadoop , Cassandra are good for batch processing; but not for real time.
Real-time; means process the data as it is happening and show reports on that.
Any ideas or suggestions ?
Comment: With virtually no facts on environments etc., there's only room for speculation.
Answer: Have you looked into the Storm project? It's used by Twitter. It's like real-time Hadoop.
We use it for one of our stream processing project. It's awesome. Documentation, development, deployment, scalability awesome. We recently ran a 20K message/sec with processing (storing in Cassandra, modifying and broadcasting, calculating mean), it worked reliably and like magic. Definitely worth giving a shot. The mailing list is very friendly, I rarely had to use it to ask a question.
Answer: You can process TBs of data with the same technologies as you can process 1 MB of data, but it will take longer.
I don't see how you intend to use the data in "real time" and I suspect you mean real world.
If you mean quickly, then you need to summarise the data for human consumption.  You can only present to the user kilo-bytes or mega-bytes of information at once.
Using memory mapped files can make this more efficient if you have a need to load the data all at once. This can be used to process tens of millions of records per second.
Answer: Check this page: http://hadoop.apache.org/
There are listed related frameworks/libraries to work with large amount of data in distributed environment.


System of polynomial equations with a known root

Question: I have 5 polynomial equations for 5 variables and I know that the set of roots is finite. All coefficients are integers. Ultimately I'd like to find all roots but finding the Groebner basis is impossible it seems (I tried maple, mathematica, sympy) probably because it takes too long or too much memory. But I found a rather simple root just by looking at the equations :) Now I'd like to use the fact that 1 root is known to somehow reduce the set of polynomials to lower order ones, if possible, in order to simplify the problem. How would I go about this?
Comment: Why do you think you need to find **a** Groebner basis to find the roots?
Comment: @Somos, Gröbner bases computations is one of the main tools for finding polynomial gcd's and thus solving systems of multivariate polynomial equations.
Comment: "One of" but not the only tool. Have you tried resultants? Also, have you tried to substitute the one known root into the five eqatuions?
Comment: is computing the resultant more efficient (from the computational viewpoint) than computing the Gröbner basis?
Comment: Software you listed is not know for having very good Grobner bases implementations.
Answer: If $p = (a_1,\dotsc,a_n)$ is a known solution and your system of equations is given by the ideal $I$, then a system of equations for all the other solutions is given as follows. Let $m_p = (x_1-a_1,\dotsc,x_n-a_n)$ be the maximal ideal corresponding to $p$. Then the saturation $I:m_p^\infty$ given by
$$
  I:m_p^{\infty} = \{ f : \exists n, f m_p^n \subseteq I \}
$$
is an ideal whose solutions (vanishing points) are precisely the solutions of $I$ other than $p$. This is under the assumption that $p$ is an isolated solution of $I$, which is the case since you know $I$ has finitely many solutions. See https://en.wikipedia.org/wiki/Ideal_quotient.
The saturation can be computed by Gröbner basis methods. For example, Macaulay2 has a command to compute the saturation. Just a guess here, but my feeling is that the saturation is easier to compute than finding the solutions other than $p$; now, whether $I:m_p^{\infty}$ is easier to solve, enough to justify that extra saturation computation, is more of a question. It probably depends on your particular ideal.
Perhaps a better approach is via numerical algebraic geometry, represented by software such as
Bertini,
PHCpack,
etc.
These software packages are exactly designed to find solutions of polynomial systems like yours. Your system is square (5 variables, 5 equations) and has finitely many solutions. If you're okay with numerical solutions, then Bertini or one of the others might be able to solve it for you. If you need "exact" solutions, then with the numerical solutions in hand, you could try something like LLL to recover "exact" solutions.
Comment: In the end Bertini proved the most useful, it could find numerically all the roots of the original set of polynomials (including the analytically known one as well). It definitely beats maple/mathematica/sympy in this class of problems.


Arduino as AVR Programmer

Question: Can you use the Arduino as an AVR programmer?
Comment: Did you have a look at [this page](http://arduino.cc/en/Tutorial/ArduinoISP)? Btw, I found it by googling the exact title of your question.
Comment: Great. Thanks found it. So I have put the cables in and I am goiong to use Minimal Circuit (Eliminating the External Clock) form the http://arduino.cc/en/Tutorial/ArduinoToBreadboard
Answer: I use the mega-isp solution mentioned above - the Arduino avrisp sketch is here
http://code.google.com/p/mega-isp/downloads/list
I do not use the shield they have - I made up a simple cable using two 6 pin dual-in-line header sockets to fit the programming ISP connector on your Arduino. (I did not have two dil sockets so I used standard single in line and superglued two 3 pin sockets together.
You then need a piece of ribbon cable or some wire.

Connect each pin on one socket the the corresponding one on the other, with the exception of pin 5 = Reset.
Connect one end of the cable to pin 5 - this is the end that will connect to the target AVR that you wish to program. Connect the other end of the pin 5 wire to a floating pin connector.
To use connect the cable to the arduino by placing over the ISP programming connector and connecting the floating lead to digital 10, connect the other end to the target ISP connector. You need to ensure that the pin 1's match up.

Program with avrdude using
avrdude -P com7 -p t2313 -c avrisp -b 19200 -U flash:w:fred.hex
where
com7 - the com port that the Arduino based programmer is on
t2313 - the type of AVR you wish to program (m328 for ATMega328).
fred.hex - the name of the hex file you wish to progam into the target.

I have used this to program Tiny2313 with no problems.
Note: The cable will carry 5v to power the target - if the target is already powered then do not connect pin 2 of the cable.
Comment: FYI: The mega-isp sketch is now included with the Arduino software as of version 0018 and no longer needs to be downloaded separately; it's located under File|Examples, named ArduinoISP.
Answer: This solution works great too:  Kimio Kosaka avrdude-serjtag method
If you have assembled you own computers you may have spare case mounted USB cables/connectors that often come with new moherboards.  Just wack off the USB end and you can use the motherboard connector as the ISP connector.
A batch file like this can be used:  (This is for the 328 chips, will set the fuses for high speed transfer and then upload the bootloader, and setting the lock bits when finished.
avrdude -c diecimila -P ft0 -p m328p -B 4800 -U lock:w:0x3F:m -U efuse:w:0x05:m
-U hfuse:w:0xDA:m -U lfuse:w:0xFF:m

avrdude -c diecimila -P ft0 -p m328p -U flash:w:ATmegaBOOT_168_atmega328.hex -U
efuse:w:0x05:m -U hfuse:w:0xDA:m -U lfuse:w:0xFF:m -U lock:w:0x0F:m

Answer: Yes, you can use the Arduino as a AVR programmer!
Take a look at the mega-isp project.
Answer: If you need hi-voltage programming (you have an otherwise dead chip) you can try this solution
http://www.mightyohm.com/blog/2008/09/arduino-based-avr-high-voltage-programmer/
Answer: The answers from 2009 are a bit outdated now that the standard Arduino IDE includes ArduinoISP which was based on Mega-ISP but is now officially supported by Arduino.cc.

Arduino as AVR Programmer


Using Vim key bindings in Onenote

Question: I found ViEmu, which allows you to use Vim key bindings in Visual Studio and certain Office applications. Does anyone know of similar software for using Vim key bindings in Microsoft Onenote? Free or Open Source is a plus, but any options would be appreciated.
Answer: You should be able to do with AutoIt (or possibly AutoHotkey) scripting, but I could not find anything that has already been written.
Comment: I have written a vim plugin for autohotkey. You can find it here: https://github.com/idvorkin/Vim-Keybindings-For-Onenote. If this is helpful, upvote my answer below :)
Answer: Vim-Keybindings-For-Onenote brings the power of VI to onenote via an AutoHotkey plugin.
The plugin has many of the common key bindings, including the folding commands to help manage OneNote lists.
Some advanced key bindings (e.g. 5dfa) are not implemented, but if there are keybindings you'd like added, the author (that's me), will help as he can.
Comment: Thx, its not that good, but still a lot better than no Vim keybindings :D
Answer: I do know the shortcuts for OneNote, but you don't understand the level of data processing, the volume of content/text processing that even a newbie VIM user outpaces... you.

Not every application interface can or should support a VIM-style interface

Although this is true, the users that made comments pointing out this obvious fact are totally missing the point.  The point that they are missing is that there is a level of productivity and efficacy that information workers achieve when they can keep their hands on the keyboard constantly.
Consider a developer; fundamentally they operate within a text editor as source code is created or maintained.  Maybe a few emails are written too.  Hopefully, ample documentation for the codebase is also created and maintained.  Believe it or not, the time that it takes to move a hand from the keyboard to the mouse adds up to be significant over the course of a day.
Sure, GUI applications have shortcuts too.  You're still missing the point.  VIM's interface provides complex and flexible functionality while requiring the minimal amount of keystrokes.
OneNote's disgustingly obese interface and running process profile aside; M$ is generally pretty good about having standard/consistent shortcuts across all apps.  Consistency is important and so give Bill his due credit there, but consider this: what is/are the keyboard keystroke(s) required to repeat the last atomic editing action in OneNote or Word?  The minimum is one 3-key combination (highlight last word) followed by two 2-key combinations (Copy then paste).
For example:

Task: modify the word "int" to "void" for the beginning of several functions.
Given: Each line to be modified has the form \t\tint someFunction(void);
Given: You have just replace "int" with "void" for the first function
Given: You need to repeat this action 5 more times.

*Assume: the word being replaced is highlighted (i.e. selected as a whole), then "v-o-i-d" is typed, and then...
1) Ctrl+Shift+ to select the last inserted word
 2) Ctrl+C *to copy the word;
 3) We'll ignore keystrokes to move to the next position, for simplicity, putting the cursor in front of the "i" character in the word being replaced.
 4) Ctrl+Shift+ to select the next word to be replaced
 5) Ctrl+V to overwrite the selected word with "static"
 6) Repeat steps 3-4 for all of the required modifications.
To accomplish the same task in VIM

*Assume: the word being replaced is selected as a whole (via visual mode or the "cw" sequence), then "v-o-i-d" is typed, and then...
1) We'll ignore keystrokes to move into the next position putting the cursor on the "i", the first character, in the word being replaced.
 2) "." *to duplicate the last edit action, which was "v-o-i-d"
 3) Repeat steps 1 & 2
When you are spending 8 to 10 hours in a text editor each day the VIM style interface adds up considerably to enhance productivity.  That was a contrived example above, but you should realize that switching between files, viewing two files at once in the same GUI or shell, saving changes, and exiting the editor back to a terminal prompt (or back to the top-level app if not using a terminal)... all of these actions are done with similar minimalistic and simple key combinations.
To Save and Quit:
VIM:
 1) "wq"
 2)
OneNote:
 1) Alt+f
 2) s,
 3) Alt+f
 4) x

Oh, I'm not done
What do you mean you can define a macro or complex series of steps, bind it to a key, and then execute that complex series of steps repeatedly (e.g. A VIM macro like "10 @i" would execute the macro bound/identified by the "i" key 10 times in a row).  That can be done 100, 1000, a 100,000,000 times without any trouble at all.
Answer: Nope.
Not a very helpful answer, but seriously now people - not every application has a Vim oriented key bindings. They are a different app.
If it helps, here is the list of Onenote shortcuts
Comment: sometimes, I consider vim is only keybindings and not even a program :)
Comment: +1 for this answer. Even if I really enjoy vim but somehow, you cannot do vim every where.
But if you really a vim user, you should use plain txt with markdown syntax for notes I think :)
Comment: @Vdt - No you shouldn't. You should use whatever notes application you like. Vim is just another program , not a religion!
Answer: Boooo ViEMU
I tried ViEMU, but ultimately was unsatisfied.  After that I discovered VisVIM.  If I recoall, ViEMU didn't implement large portions of VIM functionality.
Hooray VisVIM
Simply follow the instructions found in the %VIMFILEs%\README_VisVim.txt document that is installed along with the standard GVIM installation package for Windows.
Answer: I think GlobalVim is a perfect answer to this question.
GlobalVim has many features of vim and can work across all input situations. Registers, macro-recording, pattern replacement, and python expression evaluation...
I love this tool so much.
Comment: The link to GlobalVim used here is now dead but this seems to be another way of looking at it https://apps.microsoft.com/store/detail/globalvimgeekey/9PDQ9H0CVLMS?hl=en-nz≷=nz .
Answer: I'm looking for the same thing with Emacs-style key-bindings (gotta love vi/emacs).
Anyway I've got key bindings working in MS Word (for emacs that is), and have to believe something similar exists but I've just started using OneNote.
My next step is to look for .NET or VBA control over OneNote.  That'll be the key to controlling OneNote using the key bindings you prefer (or that's my best guess).
Comment: As some of my geek-friends (that's a compliment) used to say; "the best thing about EMACS is that it's key-bindings can be configuration in [VIM][1].

 [1]: http://www.vim.org/scripts/script.php?script_id=300

If you look into the link above maybe you can get the Emacs keyboard configuration you prefer, but leverage VisVIM's integration with Visual Studio.

If you follow the VisVIM installation steps you will be led to the interface in Visual Studio that allows you to configure external applications.  In general, OLE capable applications should integrate well.  [I found this too][2]
Comment: I found [this][1] too.

 [1]: http://www.gnu.org/software/emacs/windows/old/faq10.html
Answer: I use the excellent https://github.com/rcmdnk/vim_ahk library which is currently being maintained (April 2020).
I use the https://github.com/ililim/dual-key-remap C app to remap CapsLock, as I found that using an Autohotkey script caused issues.
And I've blogged about my experiences here: https://davemateer.com/2020/04/10/OneNote-with-Vim
Using Vim in OneNote makes me very happy!

Using Vim key bindings in Onenote


Electronic authorization for US passport holder born in Russia

Question: I have a one-year old son. He was born in Russia, but has already an American passport. He also currently lives in Russia. Does I need to fill out an electronic authorization form for him to travel to Mexico.
Thank you for your assistance.
Answer: No. As a US citizen, your son has visa-free access to Mexico for up to 180 days. See Visa policy of Mexico for more information.
If your son has any other citizenships (like Russian for example, but you didn't say either way), that doesn't matter if he enters Mexico using a US passport.


How does one have believe in God?

Question: My probleme is that i wnated to become a believer but not a believer who just believes without knowledge and certianity .And i dont know why even though i saw the signs in the universe like the fine tuned universe and i still didn't  become a believer so i realise that my mind is deluded and is not able to find the truth and has become irrational , as it is said in the quran that even if the disbelievers see the signs they deny and i am one of that,so how to come out of it and how to fix this irrationality of mind and i don't  know why i don't accept the signs
Comment: have you read quran?
Answer: Read miracles of Qur'an and science. Don't think much about Allah(who you called God). Allah has forbidden people to think about him and advised to think about Allah's creature. Just believe that there is Allah. But don't think how is Allah, What is Allah, How Allah works etc. Just think of Allah's creature.
Intention of your making question is a great sign that you are going to be a believer. You will be a believer Insha'Allah.
Answer: How does one evaluate evidence?
They inquire, gather information, reflect on the stuff (evidence, theories, hypothesis, stories, etc) and then at some point, pick a position.
Later, new information might come to light, and the cycle repeats until you the person inquiring is feeling somewhat secure about your revised position or existing position.
The Qur'an claims, in several places, over and over again, that there is plenty of evidence for the belief in God.
May God make your inquiry easy, productive, and ultimately, favourable to your destiny with God.
Answer: if you believe that this universe is really beautiful
then you also have to believe that the universe does not appear by itself and there is a creator
Comment: well , even though sometimes i think that it is beautiful and i think that  "Something can never come from nothing " even after that i m a disbeliever and i am a hypocrite
Comment: @Sauedur if you believe that something cannot come from nothing (i.e. 0+0=1) then, you must believe that there is a creator. Something that always existed that created the universe. The universe as we know it (i.e. energy and matter cannot exist infinitely, this is logically impossible).

How does one have believe in God?


Cannot Edit/Move/Transfer files via SCP to Linux Server

Question: I have a Linux server running Debian 9 to which I am trying to send/edit files to via WinSCP from my Windows machine. I am authenticating the connection via the SCP protocol with a user named: ASCUSER. Here is the permission/group information for ASCUSER:
/etc/apache2$ id -nG ascuser
ascuser root adm sudo www-data plugdev netdev lpadmin wwwpub

And here are the permissions/group accesses files I am trying to manipulate:
Directory: /etc/apache2
/etc$ ls -l apache2
total 88
-rw-r--r-- 1 root root  7224 Sep 19  2017 apache2.conf
drwxr-xr-x 2 root root  4096 Oct 17  2019 conf-available
drwxr-xr-x 2 root root  4096 Nov 19  2018 conf-enabled
-rw-r--r-- 1 root root  1782 Sep 19  2017 envvars
-rw-r--r-- 1 root root 31063 Sep 19  2017 magic
drwxr-xr-x 2 root root 16384 Mar 11  2020 mods-available
drwxr-xr-x 2 root root  4096 Aug 20  2019 mods-enabled
-rw-r--r-- 1 root root   320 Jul 10  2018 ports.conf
-rw-r--r-- 1 root root   323 Jul 10  2018 ports.conf~
drwxr-xr-x 2 root root  4096 Oct 17  2019 sites-available
drwxr-xr-x 2 root root  4096 Aug 20  2019 sites-enabled

Specifically apache2.conf. From my understanding both the owner (root) and the group (root) should have access to this file and given that ASCUSER is a part of the root group, I believe it should have access too. However anytime I try to edit the file externally and internally, or attempt to I get an access denied error:
Copying file 'a long temporary file address to where windows stores scp related temp files for scp transfer' failed.
scp: /etc/apache2/apache2.conf: Permission denied`

I'm not sure what I am missing at this point?
Answer: See
-rw-r--r-- 1 root root  7224 Sep 19  2017 apache2.conf
    ^^

Group root has the permission to read the file but not to write it, so user ascuser cannot edit the file.


How to fry tortillas for poori?

Question: Whenever I deep fry tortillas to use as poori (as in halwa poori) it becomes very crispy and hard. I want to know how can I keep ot soft?
I use uncooked tortillas.
Comment: I admit that I don't know much about Indian cuisine, but somehow this situation sounds strange. Are you sure that it is supposed to be soft, because deep fried things are normally hard and crispy? And if it indeed has to be soft, are you sure that it can be done with a tortilla?
Comment: I don't know about this general case, but in general : (1) Don't cook it as long.  (2) Serve it before it has a chance to steam out or cool off.
Comment: Flour or corn tortillas? Are you making them yourself? I have never seen uncooked tortillas in a store.
Comment: Local groceries in the SW USA have raw flour tortillas. It's also easy enough to find masa prepared for corn tortillas. I suspect OP is using flour tortillas. Raw flour tortillas only need about 30 seconds on a dry, clean griddle.
Answer: It's a late answer, but I do this all the time when I'm feeling lazy and don't want to make traditional roti. Heat up oil to 300 to 350 in a skillet .about 2 inches of oil. Or use your deep fryer at 350, just make sure it's large enough. The most important  thing is your oil needs to be up to temperature.  As soon as you toss in the tortilla it should automatically  pop and bubble up .count to 15 seconds and flip for 10 more seconds....let it drain on paper towels in a large bowl and cover with a kitchen towel to let the steam seep back in to keep it soft and moist....if it's crunchy it's because  your oil wasn't hot enough or it just sat too long frying...the while frying  process shouldn't exceed 25 seconds.
By the way I used the burrito tortilla flour type. Burritos  are bigger.
Answer: A tortilla is always going to get hard when deep fried as it's very thin and dry. There's no air or moisture to puff up in a tortilla, so I don't see how you would be able to make authentic poori with them. I've never made them myself but my understanding is that you need to make a dough, roll it to about 1cm thick and fry it.
Answer: While preparing the dough, add a tablespoon of semolina that's already been soaked in warm water and a little sugar. You are sure to get your pooris to puff up. Its a thumb rule for preparing pooris. They'll be crisp when fried but cool down and become soft.

How to fry tortillas for poori?


How to append Audio Strips from One Blender VSE to another Blender VSE

Question: I am having a Blender file with an image strip and four nos. of audio strips (as shown in 'A', at the attached Screenshot). I would like to place all of the audio strips at the exact frames as 'A', at a fresh VSE of a different blender file (in 'B', at the attached Screenshot).
2.  The main reason is that in the Blender file 'A', the original Animation was done and due the size of the Blender file (may be), the image quality of the appended image strips appears different from the original rendered image. However, when the rendered image is appended in a fresh blender file, the original image quality can be retrieved but if I do so, the all audio strips are required to be placed manually, since, I don't know how to bring all the image strips from one Blender VSE to another Blender VSE.
3.  This is also a general query because in this short duration and for four nos. of audio strips, this might not be a tedious process if I do manually, but for a large blender files where there are many nos. of audio files, a solution is required as to how audio strips can be appended in a fresh Blender file at the exact frame.
Comment: Well, I guess the easiest thing would be to simply change the _Color Management_ in A, because I suspect that is what is making your image sequence look different. If you rendered it with let's say _Filmic_ and _High Contrast_ for example and saved the images like that, adding them in the image sequencer would now apply those view transforms a second time on the images. Set _Color Management_ > _View Transform_ to _Standard_, _Look_ to _None_, _Exposure_ to 0 and _Gamma_ to 1 and see if the image sequence still looks wrong.
Comment: Firstly, Thanks for your reply. Your answer developed the quality of the image from its initial appearance. However, the original quality could not be retrieved. a Google drive link is shared here for your observation, what it looks now vs. the original rendered image quality.  https://drive.google.com/file/d/15zTa7yDoCwn2iS-RTrxSqrNuwMBZwFdU/view?usp=drive_link
Comment: Honestly, the comparison is already visible in the question - just from seeing two different appearances of an image it is hard to examine why they differ, because they shouldn't so there must be a reason behind this. For copying the audio strips from A to B there is no option to do that.
Answer: In my example I suppose that the first audio strip starts at frame 10:
Select all audio strips that have to be copied, press Ctrl C.
Open the new file, set the VSE time cursor to frame 10, press Ctrl V.


Creating HowTo section for Open Source Software tools or best practices in GIS Stack Exchange?

Question: I sometimes try to embed  examples and scripts into the Q&A discourse and wonder if we could build a browsable well structured HowTo section for things like the usage of tools or best practice solutions?
Answer: What you have described in your very brief question sounds like Canonical Q&As.  In principle I think they can be accommodated within focussed Q&A on Main, but they should still conform to the protocols that are in place for any Q&A that is to be hosted on Main.
However, I think by searching this site for canonical and looking for canonical Q&As on Main, any successes that we have had creating and maintaining them have been few and far between.
I suspect the reason is that we as volunteers underestimate how much effort is involved in creating and maintaining them until we have done one or a few, and run out of steam.
An initiative that you may want to follow is Warlords of Documentation: A Proposed Expansion of Stack Overflow.  If providing documentation, in addition to focussed Q&A, can be shown to work on Stack Overflow, then in time we may see it spread to GIS SE.  However, I think anything like that here is still well into the future.
Personally, the terms "HowTo" and "Best Practice" are ones that attract me to open questions to assess whether they really belong amongst focussed Q&A, and I often find that they do not, because I think they tend to use unclear language or are designed to try and attract multiple answers.  Focussed Q&A is about trying to find a single answer, notwithstanding that there may be multiple (usually 5 or less) candidates for that offered, so that users can vote as to which they think answers the question most clearly.
Comment: For my personal understanding if I do Q&A. I have to live with the a trade off between the public or people driven solution finding process, that contains **sometimes a teaching concept** and the **repetion of answers** within a discourse to present material / solutions that are missed or distributed over the WEB or GIS SE as teaching material?
Comment: @huckfinn You have placed a question mark on what looks like a statement.  Can you clarify what you are asking in this comment, please?
Comment: Your answer is a very good one and I've rushed over Warlords of Documentation stuff and see that the "Creation of HowTo..." has more side effects in a community sense, I not reflected before. One solution cold be to consider your own Q&A stuff as a **trade of** and handle the repetition part for myself and the question part: Is it really a trade off.. ..sorry for the inner dialog outside..


Update a previous version of plugin when the new plugin is built from the scratch

Question: I'm seeking help and suggestion from all of you. I've built a plugin from the scratch and now instructed to update the previous version of that plugin. But the new version that I've created is totally different from the previous version. The name of the files, folders, project structure and database(I've created few tables not using anything from the old) even the text-domain is changed. I've searched through the internet to see how update works and found wordpress maintains a svn repository and maintain a tag folder for versions. But I'm not sure if everything is changed will that work. What should I be concerned about updating a previous version of a plugin. I'm looking for you kind advice or solution here what would be the best for me in this situation so that the users can see a new version comes in and a single click will update their previous version. Thank you.
Answer: If you put your plugin in the WP Repository, and

change the version number in the readme.txt file
put the new code in a new 'tags' folder with the version as the folder name
also put the new code in the root of your repository (and I also put it in the 'trunk' folder
and do the SVN Update thing

Then anyone with the plugin installed will get a notice about the update via the Admin, Update screen. And updating it will get the latest version installed on their WP system.
I'd put some sort of notice on the Settings screen about the new version, in addition to the needed information in the readme.txt file , which is used to display text on the various pages on your WP plugin page.
Comment: Rick thank you so much. I'll give it a try and if everything goes fine then I'll mark your answer as correct.
Comment: Rick I did all the things that you said. Created versions in Tag folder. Put everything from trunk to tag. Also changed the stable tag in trunk/readme.txt and put all the code in the root of my repo. Then commit. Then update svn. I can see my code actually committed and updated in svn repo. But the problem is that I don't get any update notice in admin area plugin page. Don't know why.
Comment: I put the new version in 'trunk', the tag folder ("2.1" for version 2.1) and the root folder locally. Then 'commit' from local to repository, selecting all files, with some text in the comment-field-thing before committ. A few minutes later, I get an email from WP that all is well. Then a bit later (not immediately), I do the 'update' check on a test site that has that plugin active. And the new version is 'found'. Note that the update won't be found immediately; I usually wait about an hour.
Comment: Rick you're so right. I found my update notice. It works! Thank you.


How to show critical path INCLUDING completed tasks (in MS Project 2010)

Question: My project is 75% complete and I have no problem getting a nice view in MS Project showing the remaining critical path.  However, I want a view that shows how we got to this point, in other words I want to see the full critical path of the project, including tasks that have already been completed at this point.  Is there a way to clearly show this?
Answer: You are describing something like an as-built critical path, which is not easily created even in the best of circumstances.

MSP sets the Critical flag based on total slack, but total slack becomes meaningless for completed tasks.  Thus, completed tasks are never "Critical."
Conceivably, you could implement some very rigorous status-and-update procedures to memorialize the (future) critical path based on total slack at each update window – i.e. just before marking the task complete.  Then at some future time you would be able to look back through your marks to "remember" which tasks were critical at the time of their completion.  I don't know of anyone who does this.  Obviously, you can't do this after the fact.
You can also use a macro or an add-in to trace driving logic backward from a project completion milestone to the project start, including completed tasks if you like.  I routinely use this approach, and it yields good insight, subject to the accuracy of the logic and the Actual Start and Actual Finish dates.
Comment: Thank you for understanding the question and for the clear response.  I think your #2 could work, it still seems surprising to me that this is not built in to MSP in some form for reporting what was the critical path at the end of the project.
Comment: Fundamentally, project managers need to look forward, not back.  An as-built critical path is most useful to forensic consultants resolving disputes long after completion.  They essentially apply #2 retrospectively - its a tedious process, largely because the "actual" dates stored in the project are not supported by contemporaneous data (i.e. they're usually wrong.)
Comment: As noted, I typically trace driving logic from beginning to end of project using an add-in.  If the actual dates are accurate there will often be gaps in this path that may need to be explored.
Comment: Agreed on looking forward.  The only problem is when presenting the latest schedule to a manager two levels above who now only has visibility to the current issue causing delays to the project.  This causes the manager to be unaware of the other delays from other tasks/resources prior to that point.  Near the end of the project this is especially important as the currently slipping/delayed task might be wrongfully perceived by said manager as the main cause of the accumulated delays throughout the project.  Of course at one point during previous status updates those other issues were presented
Comment: The add-in that I use all the time for such purposes is called BPC Logic Filter.  We developed it for internal use in our company, but we routinely share it with others that have a similar need.
Answer: you can use a costumed column "Flag", and put a Yes for all the original critical tasks. Later you may have a view by groups, grouping by this costumized flag as criteria, that will show you in a separate group your original critical tasks, showing the progress of the original critical path, which is at the end the real progress of the whole project.


Difference effect filter in before and after amplifier

Question: Is there any difference between low pass filter that put before amplifier and after amplifier? Which one is good for PC audio amplifier?
Answer: When you amplify something, you are increasing the power.  If you look at the cost of components, it will cost you less to filter a "pre-amped" signal.
Also, why would you want to amplify the "dirty" parts of a signal?
Clean it up, then amplify.
Comment: Agreed.  @VladimirCravero Edited.
Comment: I've got the feeling you meant "power" instead of voltage... Or you might need to peek at the the definition of "amplifier".
Comment: There must be plenty of reasons to amplify and then filter, so long as you won't be saturating.  For example, filtering the inputs on an instrumentation amp will often negatively impact your CMRR
Answer: The answer is yes in ideal circuit theory and the approximation to it that we call "The Real World".
Consider an ideal RC low-pass filter.  The open-circuit output voltage, due to an input voltage \$V_s\$ is
$$V_{o} = V_s \frac{1}{1 + j \omega RC}$$
However, if one connects a load impedance \$Z_L\$ to the output of this filter, the loaded output voltage is
$$V_{ol} = V_s \frac{Z_L}{R + Z_L}\frac{1}{1 + j\omega \left( R||Z_L\right)C}$$
Thus, the DC gain and frequency response of our low-pass filter depends on the load \$Z_L\$
However, if there is a good amplifier (high input impedance, low output impedance) between the low-pass filter and the load, the DC gain and frequency response will effectively be independent of \$Z_L\$.
There are other reasons you might want the filter before the amplifier rather than after.  For example:

With the low-pass filter before the amplifier, the amplifier is not
required to needlessly amplify frequencies well above the corner
frequency.
If the low-pass filter is after the amplifier, the power delivered to
the load must pass through the filter.

and which one is good for PC audio amplifier?

Without more details of your application, it isn't clear what the 'good' is.
Comment: I want to make a bridge amplifier but the when i put low pass filter on the second amplifier it affect both of them.
Answer: Ideally there is no difference. If the filter is just a mathematical thing that you put in a signal processing chain, in this case its position it's irrelevant.
Luckily we live in the real world, so math has its own limits.
If you are interested only in the low portion of the spectrum of your signal, then why would you amplify it all? Amplifying costs power, and that's something you generally want to save. Moreover a filter after an amplifier should handle more powerful (aka amplified) signals, so it will need "bigger", more expensive components. Processing a signal before it gets amplified is not the golden rule, there are tons of situations where the opposite is true, but I've got the feeling that you want to build a set of loudspeakers thus your input is line signal, while your output is a somewhat powerful signal meant to drive the speakers. If that's the case you will need a LP filter on your input unless you want any kind of signal messing around in your circuit. If you don't use a LP and your amplifier has a somewhat wide band it can amplify some high frequency signal which you can't even hear, wasting a lot of power... For nothing.


How to use different columns of a csv file data as different layers for weighted overlay analysis in QGIS?

Question: I have a CSV file like this:

I would like to do a weight overlay analysis for each column of the CSV and present it as a layer of the map of United States of America.
The final result should look like this map:
Comment: I'd import the csv through Layer->Add Layer->Add delimited text layer. If you have geometry, use it, otherwise get the corresponding Area shapefile from somewhere and perform a table join on the name (you might need to update the Area name column). Once that done, duplicate the layers (right click on it -> duplicate) until you have enough version to carry out the analysis you want to do. You need to add more details to your question if hope to obtain a more detailed answer (such as an example of the result you want to obtain).
Comment: @Victor get shape file as xml and shp file , how can it can be joined with original csv file ?
Comment: You have to import the data as @Victor described. Than you can perform join tables by uniqe coresponding attribute in data. Joins menu is in vector layer properties, see [QGIS Joins documentation](http://docs.qgis.org/2.14/en/docs/user_manual/working_with_vector/vector_properties.html?highlight=join#joins-menu)
Comment: i imported the file and trying to join but i m getting NULL of all the columns joined frm csv file to the shapefile
Comment: Do you want your final unit of analysis to be counties or states?
Comment: @the_darkside counties
Answer: For the county shapefile, you can download from US Census.
Use the 20m zip.  Unzip and import into QGIS, call it counties
When you open the shapefile, you will notice that there is a column called STATEFP - that is the FIPS code.  Each state has a unique FIPS code and you can find the key here.
What you'll need to do is copy these 52 codes and their corresponding state abbreviation (if you include Puerto Rico and Guam) into a spreadsheat. You should have two columns.  Save this as a csv and import into QGIS as a delimited text layer - call it stateKey.  Then, in your csv file with all of your demographic data - split the Area_name column using a comma separator which will create two seaprate columns - County Name and State Abbreviation.  You can do this with the Data > Text to Columns in OpenOffice and there is a similar function in Excel. Then import all of your data into QGIS as a delimited text layer, call it data.
Now you will perform a few joins.  First, you will join the stateKey to counties.  Right click counties > properties > joins then join stateKey by the FIPS code and keep all columns.
Now you have a counties shapefile with state abbreviations.
Next, perform the same step, except this time join counties to data by state abbreviation.  And voila.
Now you can classify the counties by whichever attribute you choose.  For example.  Right click counties > properties > style > graduated.   Then you can choose the column which you want to visualize.
For more complex modeling, you could consult the Processing Modeler tutorial
Comment: my map became invisible when i changed style > graduated :(
Comment: under `graduated`, after choosing the column ,then you have to use `classify` and then hit `apply`
Comment: it did that still map is not visible


Plots in a paper using different software

Question: Can I provide two plots made using two different softwares in a scientific paper? For example, one is plotted using Origin and another is plotted using Python?
Comment: Why do you think that you could not do that?
Answer: It is not unusual to have plots created with different software if they are used to display different kind of data. But I would not plot the same kind of data in the same paper once with one software and once with another (unless there is a very convincing reason to do so, in case the reason should also be provided).
Answer: Using different applications for different plots is not uncommon, especially when there are collaborations among different groups which are accustomed to  different applications.
For instance, I have a number of papers published with various groups across the world. I'm used to plotting graphs by using the workflow Matlab->matlab2tikz, whereas other coauthors of mine are more confident with Origin. For diagrams, I usually work with Inkscape, but other groups may have other preferences.
Most of the time, we didn't have any issue, but there have been rare occasions in which a reviewer (you know, that reviewer #2, the nitpicking one) asked us to make the diagrams more uniform across a paper. This request was typically not referred to plots but to circuit diagrams, and it was more related to the symbols used rather than the software used, but indeed it's easier to guarantee uniformity when the same software is used (in cases like this one, when I'm the first author, I usually volunteer to redraw everything in a uniform way with the same software).
Answer: Q: Can I provide two plots made using two different softwares in a scientific paper?
A: Unless a publisher (and their review process) tells you otherwise, you can do whatever you want for figures.
Ideally, the plots in your paper will be consistent formatting with each other (e.g., same tick styles, label fonts).
Personally, I have seen papers where plots come from different programs, and I could tell because the figures mismatched each other with style.
As long as the formatting of the plots does not distract from the science you are presenting, I would not be worried about the format.
Thus, I think consistent and readable formatting is more important that the program used for your plots.
I would encourage you to focus on your plotting skills rather than the program used to create your plots.
Answer: It will depend on how the journal operates. Many journals will be able to accept images you create. Others will want the data for a graph to typeset it themselves. Others will accept images sometimes for some types of figures, and want to plot the data themselves for others. For images, there will be image file formats they can accept, and others they cannot. They will also have opinions on what format and resolution looks best.
Also, these things may change over time. A journal that acquires new publishing software may find that new sets of restrictions exist.
Contact the journal to find out what they can deal with, and what restrictions there are. They probably have a standard response for such questions, because they probably get it frequently.


Confused about Ramsey technique

Question: Assume we have a 2 level system with the frequency between the 2 levels $\omega_0$ and ignore the lifetime of the upper state. In order to measure the transition frequency using Ramsey technique, you apply 2 $\pi/2$ pulses separated by a time $T$. We have that the probability of finding an atom in the excited sate under the interaction with light (assuming strong field i.e. not using perturbation theory) is given by: $\frac{\Omega^2}{W^2}sin^2(Wt/2)$ where $\Omega$ is the Rabi frequency and $W^2=\Omega^2+(\omega-\omega_0)^2$ with $\omega$ being the laser frequency (which we scan in order to find $\omega_0$). If we are on resonance, i.e. $W=\Omega$, a $\pi/2$ pulse is a pulse of duration $t=\frac{\pi}{2\Omega}$ such that, starting in the ground state, the atom becomes an equal superposition of upper and lower states. However in the Ramsey technique, we don't know $\omega_0$ beforehand (this is what we want to measure). So I am not sure I understand how we can still create an equal superposition of upper and lower level using a $\pi/2$ pulse. Assuming we use a pulse of duration $t=\frac{\pi}{2W}$, from the equation above we get that the population of the upper state is $\frac{\Omega^2}{2W^2}$ which is not $1/2$ as in the resonance case. How do we still get equal superposition of upper and lower case when we are not on resonance? Thank you
Comment: You vary the frequency, to find the frequency at which you see the effects of a $\pi/2$ pulse.
Answer: You are correct that the Ramsey sequence should be applied close to resonance, but it does not need to be perfectly on resonance -- it only needs to be close to resonance, relative to the Rabi frequency used for the $\pi/2$ pulses.
The Ramsey technique gives a measurement signal that oscillates as a function of the gap time $T$ between $\pi/2$ pulses, where the oscillation frequency is given by the detuning $\omega-\omega_0$ and the contrast is determined by the weights of the superposition produced by the $\pi/2$ pulse. In the ideal case (maximal contrast), the $\pi/2$ pulse would transfer 50% of the population to the second state; however, the signal is still usable when the $\pi/2$ is imperfect. In practice, as long as $|\omega - \omega_0| \lesssim  \Omega$, then you find from the expression that you wrote $\frac{\Omega^2}{W^2} \sin^2(Wt/2)$ that close to 50% of the population will be transferred.
If you know approximately where the resonance is to within a bandwidth of $\sim \Omega$, then Ramsey can be used to more precisely find the resonance (ultimately limited by the longest gap time $T$ that can be used). If you don't have any idea where the resonance is, then you can first find it by applying an approximate $\pi$ pulse over a wider range of frequencies and finding which frequency gives the largest population transfer.
Comment: Here is an example protocol: apply a short pulse (order ~ pi time given your expected Rabi frequency) over a wide range of frequencies. Even if the pulse time happens to be 2pi, you will still see a clear spectral feature that is symmetric around resonance (a sinc type function). After finding the resonance approximately, you can apply variable length pulses close to resonance to measure Rabi oscillations, and extract the Rabi frequency. Finally, you can apply pi/2 pulses with a variable gap time to measure the precise detuning from resonance using Ramsey.
Comment: Thanks a lot for this! It does make sense now. However, I realized I am also a bit confused about the way you actually realize the pi/2 pulse in practice. First of all you need the Rabi freq /Omega (which tells you how long the pulse should be), which is a dipole matrix element between the 2 levels. I assume that is quite hard to calculate in practice, and from what I saw, the relative errors in multi electron systems wavefunctions are about 10%-15% how do they get that value, such that they can tune the time precisely?
Comment: Also, when you don't know \omega_0, what value do you use for t, as you can't calculate W. Do you just use \Omega again i.e. you keep the pulse length as t=pi/(2*Omega) all the time and just vary the frequency?
Comment: Usually you would measure the Rabi frequency in practice by scanning to find the approximate resonance, and then driving Rabi oscillations to measure $\Omega$. (You would know in advance what order of magnitude to expect for $\Omega$, but it's hard to know all details including precise laser/MW intensity at the atoms, etc.). And yes, for Ramsey you could use a fixed time of $t=\pi/2\Omega$. (Note that the more general $\pi/2W$ is first-order insensitive to detuning from resonance.)
Comment: Oh, so you measure the Rabi freq directly. I assume you send pulses of different lengths and see where you get a maximum (for a pi pulse)? However, how do you measure the frequency in the first place (sorry i got quite confused)? Initially I thought that in an experiment, if you want to find an unknown transition you would scan the frequency over a given range until you see some (for example) fluorescence. But now I am not so sure. Don't you still need to send pulses for this freq measurement, too?
Comment: And if you are unlucky, can't it be that the length of your pulse is 2pi, such that even if you are on resonance, the system will go back to the ground state and you see no fluorescence at all? Do they scan both the frequency and pulse length at the same time? Or am I missing sometime?

Confused about Ramsey technique


Can a QFT be implemented as a physical change of the measurement basis?

Question: Suppose you had an "analog" quantum computer, where a register would store a wavefunction $\psi(x)$ where $x$ is a continuous variable (with $0\leq x\leq 1$, say). Instead of gates, you would somehow apply unitary operators to the wavefunction. In this context, it seems to me that the QFT would essentially be equivalent to changing to the momentum basis, $\psi(k)$. This could be done by using a different physical apparatus to measure the state of the register, and wouldn't require the actual application of any unitary operators to the wavefunction. Could there be a similar result for a qubit register which could be measured in two different non-commuting bases? If not, why?
Comment: When you say measure the state of the register? What are you measuring? $\hat{x}$ or $\hat{k}$? It sounds like you are thinking of the function $\psi (x)$ as classically stored by the way this is asked.
Comment: Yes, classically stored. So instead of a register you might have a sort of 'quantum abacus' which is well-enough isolated from the environment that the beads can be in superpositions of different positions on the rods. You could then use some kind of physical unitary evolution to transform the wavefunction for a single bead $\psi(x)$ into its fourier transform $\tilde{\psi}(x)$ and then measure $\hat{x}$. But alternatively you could use a different measurement apparatus to measure the momentum of the bead (measure $\hat{k}$).
Comment: My question is then whether you could use the same trick for actual qubits (e.g. superconducting loops or ion traps), where the wavefunction is defined on a finite set of values ($\psi[n]$, $0\leq n < 2^N$, where $N$ is the number of cubits). Could you then represent the QFT mapping $\psi[n] \to \psi[k]$ as a physical measurement whose eigenstates are states with definite $k$, and if so, what would the operator be that corresponds to this measurement?
Comment: You can edit your question with these clarifying comments.
Answer: Yes, you can in principle do any measurement as a direct physical operation. The real obstacle is to come up with a way of actually doing it in practice.
The basis states of QFT-ish measurement span every qubit in the register. This means that whatever physical mechanism you are using must be merging together information as large as the register. But physics is local, and your measurement is not, implying you need to build up your big information-merging measurement out of many local interactions. That set of local interactions will probably be isomorphic to quantum gates.
For example, you can do a QFT-ish measurement on photons by putting a diffraction grating between them and the detectors... but isn't putting down the grating just a ultimately roundabout way of applying a gate before measuring?
Comment: Thanks for your response, this is quite helpful. I see how the measurement might well end up being exactly like the gates it was meant to replace. I guess the question is really about where you draw the line between the "hardware" and "software" of a quantum computer. That said, can we still say there is a lower bound on the complexity of the QFT or similar operations if there is, in principle, a hypothetical machine which performs it in O(1)?
Comment: @MaxwellAifer That seems very unlikely, because in order to verify that you are in a particularly frequency eigenstate you need to fold information from all N  qubits. Using fixed-size arbitrary-distance interactions this takes at least O(log N) depth due to standard circuit bounds. Using fixed-distance interactions it takes at least O(N^(1/3)) time due to the light speed barrier in 3d space.
Comment: Wow, I had not thought of the light speed barrier, that's fascinating. I will have to read up on these circuit bounds, thanks again


What is the most effective Weightloss Drug?

Question: What is the most effective weightloss medication for dietary support?
Answer: There's not one really. The best way to lose weight is to go on a calorie deficit. This answer explains how to do a calorie deficit. It also continues to explain what your protein intake should be, which is good to know if you are weight lifting. Eat fresh produce, ie fruits and veg, so that you get your micronutrients.
Also, get active. Get on a treadmill and walk a couple/few miles. If you can, run (or work up to that point). Hit the gym and lift weights to build muscle. Muscle cells burn calories more so than fat cells.
The only supplements that I think is beneficial are protein powders and fish oil. Protein powders help one to get enough protein in (without eating stacks of meat), which is useful for bodybuilders. Fish oil has omega-3 fats and sometimes omega-6 and -9. Our bodies don't produce these so we have to consume them. However, if you're one for fish dishes then you're probably getting enough omega fats.
Finally, I have read a study that conjugated linoleic acid (CLA) was shown to be effective at fat loss, even without changing the activity level. I'm too lazy to cite that study because it was very small and only a couple of ladies benefited from CLA without needing to up their activity. The study overall didn't seem conclusive, to me, that CLA was actually all that effective. I bought CLA and took it for some time, but did not see any benefit despite increasing my activity significantly. So, as I stated in the beginning, there's not a magic pill that will make you lose weight.
Comment: On the subject of CLA... https://www.instagram.com/p/BzAWrqEB0uv/
Comment: Yup, CLA is a waste of money. Like, consuming fat is okay and all, but might as well consume fat that's in meat instead of paying a premium for sunflower seed oil (which I didn't know was CLA until a recent doctor's visit).
Comment: Actually, I just thought of an old weight loss pill that actually worked but was pretty lethal. I won't mention its name since it's a dangerous drug. `Dietary support` made me think of supplement which didn't get my brain to think of what I learned in biochemistry.


How to get all orders items by product_id?

Question: I want to get all order items by product_id not by order_id. So Please read carefully and give me a solution.
Thanks in Advance.
Comment: where you want all order, i mean for what purpose?
Comment: Ok, let me explain you. If I did many orders such in one order there are 2 items means products then in other order other products. So I need to get all ordered product list by separate order. because I need to check which options were selected by buyer in separate orders.
Comment: i have posted the answer as per your explanation.
Answer: Try below code with changes according to your needs, and do not use object manager in original implementation.
<code>$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$orderItemCollection = $objectManager->create('\Magento\Sales\Model\ResourceModel\Order\Item\Collection');
$orderItemCollection->addFieldToFilter('order_id', ORDER_ID);
$orderItemCollection->addFieldToFilter('product_id', PRODUCT_ID);

foreach ($orderItemCollection as $item)
{
    $options = $item->getProductOptions();
}
</code>


Lines on quadric surfaces

Question: Consider a smooth quadric surface $Q\subset\mathbb{P}^3$ over a field $k$. Are there natural hypotheses one can put on $k$ in order to ensure the existence of a line defined over $k$ on $Q$?
Answer: Yes, it suffices that $k$ have no nontrivial quadratic extensions.
Since the surface is geometrically $\mathbb P^1 \times \mathbb P^1$, the space of lines is geometrically a union of two copies of $\mathbb P^1$. Arithmetically, the components are defined over a quadratic extension of $k$. If there are no nontrivial quadratic extensions then they are defined over $k$.
Each component is then a form of $\mathbb P^1$. Since the anticanonical bundle has degree $2$, a section of the anticanonical bundle has zero locus a scheme of length two. Because $k$ has no nontrivial extensions of degree $2$, the zero locus consists of either one or two $k$-points, so the space parameterizing lines has a $k$-point and thus there is a rational line.
At least in characteristic not $2$, this condition is necessary, as if $k$ has a quadratic extension then it contains a nonsquare $a$ and the form $x^2 -y^2 + z^2 - a w^2$. Any line on this surface must, over $k(\sqrt{a})$, be a line on $(x+y)(x-y) + (z- \sqrt{a}w)( z+\sqrt{a}w)$, thus of the form $\alpha (x+y) + \beta (z-\sqrt{a}w) = \alpha (x-y) - \beta (z+\sqrt{a}w)=0$ or of the form $\alpha (x+y) + \beta (z+\sqrt{a}w) = \alpha (x-y) - \beta (z-\sqrt{a} w) =0$, but the Galois group exchanges these two types of lines so this is impossible.
Comment: @Arty Yes, I meant necessary. An example is given by taking $\bicup_{n=1}^{\infty} \mathbb F_{p^{2^n}}$, or the field of numbers constructible with straightedge and compass - more generally, given any field, we can consider the field generated by all quadratic extensions, then the field generated by all quadratic extensions of that, and so on, and take the limit. Yes, over $\mathbb C(t)$ the counterexample I described should work taking $a = t$.
Comment: Thank you for the answer. In the last part did you mean "this condition is necessary"? Sorry for my ignorance but what is an example of a non algebraically closed field without quadratic extensions? I am mainly interested in $k = \mathbb{C}(t)$ but I guess that $k(\sqrt{t})$ is a non trivial quadratic extension of $k$. Is this correct?
Comment: Thank you. From your answer it seems to me that the situation in higher dimension is similar. I mean if $Q^n\subset\mathbb{P}^{n+1}$ is an $n$-dimensional quadric with $n\geq 3$ and $k$ has a quadratic extension then $Q^n$ could contain no line. Is this correct?
Comment: @Art For higher $n$, having no quadratic extensions is still sufficient to ensure every quadric has a rational line, but may no longer be necessary. The same construction definitely doesn't work.
Comment: Note that for a specific field $k$ and quadric surface $Q$ you can using the description of Will to give way more concrete examples. If the characteristic of $k$ is not $2$ then the condition that the components Will talks about are defined over $k$ is equivalent to the discriminant of $Q$ being a square in $k$. And the condition that both components are isomorphic to $P^1$ is then equivalent to $Q(k) \neq \emptyset$.

Lines on quadric surfaces


(80's-90's) Spaceship heading for earth with pods containg a small robot that can build a cyborg/robot from the surrounding enviroment

Question: A film (rented VHS I think) from the late 80' or early 90's, some kind of pods found their way (don't remember how) into an spaceship heading for earth. These pods were egg/walnut shaped and orange/brown and approximately the size of a basketball. In these pods there was a small machine with tools that could use material from surrounding environment to build some kind of robot/cyborg. I remember that it used a human body as a base to build this robot/cyborg. Some people were trying to stop this ship from reaching earth but in the end it crashed and then you saw at least one surviving pod.
I think Martin Landau was in the film but I may be mixing things up.
Comment: see OP comment below confirming duplicate
Answer: This is Moontrap with Walter Koenig and Bruce Campbell. Direct release to VHS, unavailable on DVD or Bluray.
Comment: Thanks a lot, trying to remember the title of the film almost drove me crazy. I mixed up the the film with "The dark side of the moon" wich is utter s**t I found out after 2 minutes. I saw that somebody is selling the DVD on ebay and Amazon. Again, thanks a lot!
Comment: The DVD is a bootleg. Trust me, I've looked. And please accept my answer if you feel it's correct, just click the checkmark next to it.


how replace server repo file by my local repo in Git..?

Question: My problem is in my git repo there are some files..but when i commit if then due to..
git config core.autocrlf
this is true by default..

so in hex of every file it replace 0A  as 0D 0A i did commit . But after knowing this problem i change ..
git config core.autocrlf , as false

But now the problem is if i push then its showing
every thing is up to date.

I know that ok, But i have to push my new code now coz of this hex code problem in every file..
So who i con do this....
Thank's..!!
Answer: You could try, (if the push is fairly recent and nobody has yet pulled that specific commit) to:

amend your latest commit (by changing its comment for instance)
git push -force master origin in order to erase the latest commit on GitHub by your new commit, with this time the conversions being avoided.


A problem with a strange flickering/undulating effect and a related question about drivers on Ubuntu

Question: I have been having a very frustrating problem in Ubuntu. Sometimes, there is a graphical effect that can only be described as flickering or undulation. I think undulation is the most accurate one, since that is really what it looks like, like the bottom of a pool of clear water. It used to happen on windows as well, when I was doing graphically intensive things, but it started appearing on Ubuntu even when I was just browsing the internet.
I thought it might be a problem with drivers, so I tried to find proper drivers on Ubuntu. Well, this is where I got completely stuck. The proprietary drivers that apparently work the best turned out to not work for my graphics card (since it is an older card). My card is an ATI Radeon HD 4670.
I have several questions.
1) I did everything I could to find working drivers for my card on my OS (Ubuntu 13.04) but I did not find anything. What is the best driver I could get, and where could I get it? People have suggested several open source drivers already but I'm not sure which to install, and which are the best.
2) I downgraded my Xserver in an attempt to install a proprietary driver, and I could not do it. As embarrassing as it is, now I do not know how to upgrade my Xserver again. When looking for Xserver upgrades, I ultimately found four packages. I did not know which one was which, so I just left it downgraded.
Thanks!
Answer: AMD has declared the Radeon HD 2000, 3000 and 4000 series as having "legacy" support. The legacy drivers can be downloaded here:
http://support.amd.com/us/gpudownload/linux/legacy/Pages/legacy-radeon_linux.aspx
However, the support from AMD is basically nonexistent.
The legacy drivers have their share of problems, but they work well for the most part.
The best way to install the legacy drivers is using this PPA:
https://launchpad.net/~makson96/+archive/fglrx
You don't need to downgrade your X server or anything like that, the PPA handles everything.
Steps:
Open a terminal (i.e. ctrl+alt+t) and type the commands:
<code>sudo add-apt-repository ppa:makson96/fglrx
sudo apt-get update && sudo apt-get upgrade
sudo apt-get install fglrx
</code>
Then just follow the instructions (input your password, press enter, etc.)
After this, restart your computer and the new drivers should be working.
Comment: And for future reference, the best way to install _anything_ in Ubuntu (that isn't in the default repositories) is to Google for a PPA.


How to specify the domain of an attribute in an entity-relationship diagram (ERD)?

Question: In an ERD (as in, rectangles for entity types, diamonds for relationship types, ovals for attributes, etc.) how would one specify that an attribute is, say, a 5-letter word?
Answer: That sounds like Chen notation. I don't think Chen has a standard representation for attribute domains.
If you're drawing the diagrams free-hand (or using a generic diagramming program) then just write it in there. If your using specific ERD software go with what it supports.


How to figure out which key a song is written in when you know the key signature?

Question:
How to figure out the key specifically in this song?
I know that the key signature has a sharpened F, but this means that it could either be in G major or E minor. The beginning note and the ending note don't start on the tonic of the key.
Comment: No, I want to know specifically in this piece how to figure it out. I have looked at other posts already but I still can't figure it out.
Comment: The other post answers this question in general, but questions about ["identifying notes/chords/meters/other elements in songs"](https://music.stackexchange.com/help) are off-topic anyway.
Comment: @DavidBowling Thats pretty funny, because the first link is literally my own question haha. But that was more focused on the different modes and what note feels home. Here I want to deduce the signature when you only have the sheet music.
Comment: The question could almost have been 'what the heck is the time sig. for this tune?'
Answer: That song is definitely in G major. The anacrucis at the start leads straight to a G in the first full bar. (1st clue). The last note - even though it looks odd, it must be a note due to wording underneath- is also G. (2nd clue). There are no D#s which would indicate not Em, due to most songs in Em needing and having a sharpened leading note, D# in Em (3rd clue).The repeated first line also ends on G (4th clue). There is no doubt here.
However - were there D#s it could easily have been in Em. The main clue there being ending on E. It could also have been in several different modes of G major, with F# as key sig., but clues would be tonal centre. For example, if the tonal centre (home feeling) was A, then it could have been A Dorian.
Answer: The first strong beat is a G.  The last note is a G, preceded by an F#.   Pretty strong indications that the key is G major.
That last note is a 'breve'.   Twice the length of a 'semibreve'.  What do Americans call it, a 'double-whole-note'?
Comment: "What do Americans call it, a 'double-whole-note'?" Yep! At least it's not the dumbest thing our country has ever done...
Comment: Very true......
Comment: Ironic calling it a breve' - translates as 'short'...
Answer: The sample you provided is in G major. As you said, if all you know is the key signature then the key could be G major or E minor. But - the last note is a G (except the open notehead indicating the duration is not a familiar semibreve). If you sing or play through the tune, it's definitely in a major key. If it were in E minor, you'd almost certainly have one or more pairs of D# followed E. None of the D's in the tune is a D# - so it can't be E minor.
Comment: E harmonic minor scale contains a D#; E melodic minor has a D# on the ascending scale. The last note of the tune you supplied is a G because it's centered on the G line. Its duration is an old-style breve. Modern ones look a bit different. There's a wiki article showing the different shapes.
Comment: I have read that as well, but I don't understand that. Why would there be d#'s in E minor? E minor doesnt have a D sharp in the key signature right? And also, the last note isnt a G right? Thats a F. What is an open notehead actually?


Smallest rpm based linux possible?

Question: Considering Linux distributions that are based on RPM. How can we have the smallest possible of these Linuxes in size with minimum number of packages?
Answer: This looked promising:

RPM Live Linux CD     RPM Live Linux CD
  is a 120MB RedHat-based distribution
  that runs completely from CD, fits
  into around 80MB of RAM and is nearly
  indistinguishable from a system
  installed on a hard disk. Features
  include hardware recognition at boot,
  samba, dhcpd, name, xinetd, and SSH
  servers, virtual terminals, PAM, etc.
  Useful for dedicated servers, routers,
  emergency systems, cluster nodes and
  such, it does not contain an X11
  Server.

Unfortunately, distrowatch reports RPM Live Linux CD (aka Basilisk Linux) as discontinued, and the site is down.
Your best bet is probably to download a RedHat/Fedora/CentOS server CD or live CD.  To minimize the number of packages, just don't install anything you don't absolutely need--such as X or any window managers (e.g., GNOME, KDE).
It's also worth noting that there are other, non-RPM-based distros, which have been stripped down to the bare minimum, yet still have some type of package manager.  DSL (available as a 50 MB live CD) is one of the better-known tiny linux distros, and I don't think you'll find much smaller unless you look at embedded projects such as DD-WRT.
Answer: Fedora with the appliance kickstart will give you a tiny base to build upon. Be sure to edit the repos before using though.
Comment: http://fedoraproject.org/wiki/Anaconda/Kickstart
Comment: It (or another file that ends in `comps.xml` or `comps.xml.gz`) should be found in `repodata/`.
Comment: could you give some information about the link you have given? how can it help me?
Comment: thanks, but can you help me on another thing? on the Kickstart wiki page in chapter 3 it is written : "Refer to the repodata/*comps.xml file on the first CD-ROM for a list of groups[ of packages]."
but I didn't find the file in my fedora 12 DVD (X86-64). where could I find that list?
Comment: there is another question came to my mind. in the first link, there is the aos.ks file that seems to satisfy my need. but I have a question about the file: when the scripts are defining the packages to be installed we see first of all it used the --nobase option means no base package group should be installed then it begins to specify the packages like kernel and bash individually.It is ok until now but I see after those specification it comes with removing some packages.as i read i think we remove packages when we dont want them from a group.but there was no group specified,even base ignored!
Answer: You could use Suse Studio to build a tiny version of OpenSuse. The "Just Enough Operating System" base with all the defaults gives a downloadable iso file of 131MB.

Smallest rpm based linux possible?