Is there a word for an intentional misnomer?

Question: Is there a word that describes that something has been named "incorrectly" on purpose (a sort of intentional misnomer)? For example, calling someone who is very tall Shorty (or something to that effect).
Answer: If the intentional misnomer disparages something positive (as, arguably, calling a tall person Shorty does), it qualifies as a dysphemism. From The Oxford Companion to the English Language (1992):

DYSPHEMISM  In rhetoric, the use of a negative or disparaging expression to describe something or someone, such as calling a Rolls-Royce a jalopy. A cruel or offensive dysphemism is a cacophemism.

Another candidate (though not quite so apt) from the same source is meiosis:

MEIOSIS In rhetoric, a kind of understatement that dismisses or belittles, especially by using terms that make something seem less significant than it really is or ought to be: for example, calling a serious wound a scratch, or a journalist a hack or a scribbler.
Comment: I would simply add, or add simply, whichever you prefer, that naming something wrongly and intentionally is a mild form of irony and is sometimes totally lacking in imagination.   Calling a tall person "Shorty," or a milquetoast "Tiger" is just too facile!
Comment: I guess I'm thinking of a less disparaging tone, but cool word!
Comment: Plus one for "rhetoric"!
Answer: Antiphrasis! Sometimes conflated with litotes.

Antiphrasis
the usually ironic or humorous use of words in senses opposite to the generally accepted meanings (as in "this giant of 3 feet 4 inches")
[Merriam Webster]
Answer: How about malicious malapropism?
[While a malapropism is usually unintentional, the adjective suggests the deliberate twist.]
Comment: @batpigandme Maybe *jocular malapropism*?
Comment: @batpigandme or to maintain the consonance, *mischievous malapropism*?
Comment: Hmm- maybe, I don't want to suggest it's mean spirited...
Comment: Jocular malapropism is perfect (though I definitely plan on making use of mischievous malapropism when I'm feeling alliterative...)


Where is the neural network used in MCTS?

Question: Where does an engine (such as AlphaZero) use its neural network in MCTS? It shouldn't be needed to evaluate positions reached via MCTS, since I'm under the impression that only terminal game states are evaluated (checkmate or draws). Is the neural network used in the expansion portion of the MCTS algorithm? I.e., choosing which new move to expand on a leaf node, rather than randomly choosing a new move? If that's the case then it doesn't seem like the neural network plays such an important role.
Comment: For AlphaZero, have a look at their officially published paper ([open access version here](http://science.sciencemag.org/content/362/6419/1140.full?ijkey=XGd77kI6W4rSc&keytype=ref&siteid=sci)), it's clear on these details. See the MCTS discussion at the beginning, then Fig. 4 in particular and the discussions thereof.
Comment: The neural network plays the evaluation part of a traditional engine.
Answer: Neither AlphaZero, nor Lc0 (an open source project based on the AlphaZero paper), use MCTS in its pure form, because they do not perform game rollouts - the search is simply called MCTS because the way that it expands its tree is similar to MCTS.
Here are the main differences:

MCTS performs random rollouts to a termination condition (e.g. win, draw, loss) at leaf nodes to estimate to value of that node, whereas AlphaZero and Lc0 simply use the neural network to estimate the win value. They do not perform rollouts.
MCTS uses UCT to decide which node should be expanded. AlphaZero and Lc0 use the output of the neural network as an additional parameter in their versions of UCT: the neural network generates a probability associated with every possible move in the position, which allows the neural network to control the expansion of the search tree to some degree.

Lc0
Answer: Disclaimer, not an expert.
As I understand it, the process runs something like this:

Given current position, ask the neural network for a prediction on 1) the move and 2) the win probability arising from that move.
Make that move. This gets to a leaf node. Query neural network for new prediction on 1) the move and 2) the win probability arising from that move.
And so on ...
Because it's Monte Carlo Tree Search, at some points the program will back up and search the move with the next-highest win probability.
When time is up, make the move that leads to the highest win probability.

See this link for an infographic.
Comment: As far as I understand, it uses the move it explored the most, since moves that have a high win probability may not be explored enough to see if they have refutations
Answer: AlphaZero and Lc0 use a modified version of MCTS.
The neural networks in A0 and Lc0 are actually "two-headed" networks - one is a "value network," and the other is a "policy network." The value network is very simple: Given a position, it provides a probability that either side will win. Note that it is not based on color - in Lc0, 1 means that the side to move is 100% winning, and -1 means that the side that is not moving is 100% winning. The policy network, given a position, produces probabilities for each move being played.
Interestingly enough, the network gives probabilities for all theoretically legal moves, treating each piece as a "superpiece" that can move as both a queen and a knight. Illegal moves are filtered out, their probabilities set to 0 and the probabilities for the othre moves recalculated. In this way, the outputs can of fixed size.
At the beginning of MCTS, you select nodes based on the UCT value, which is a formula that balances "Explotation" (picking nodes you know are pretty good) versus "Exploration" (picking nodes that you haven't seen before.) These engines use a variant called "PUCT," or predictor UCT, which takes into account the policy network's suggestions. Then, rather than using rollouts, the network just uses the evaluation from the value network.
Dominik Klein wrote a really great book about neural networks in chess - I highly recommend you give it a read! The link is here:
https://github.com/asdfjkl/neural_network_chess


Show that $[\Bbb Q(a):\Bbb Q]=2$

Question: Let $\zeta=\zeta_{11}$.Show that the only subfield of $\Bbb Q(\zeta)$ with degree $2$ over $\Bbb Q$ is $\Bbb Q(a)$, with $a=\zeta+\zeta^3+\zeta^4+\zeta^5+\zeta^9$.
We khow that $|G=Gal(\Bbb Q(\zeta):\Bbb Q)|=10$, and $G=\langle \sigma \rangle $, which $\sigma(\zeta)=\zeta^2$ so G has unique subgroup with order 5, $\langle \sigma^2 \rangle$.We want to show that $\Bbb Q(a)=Fix(\langle \sigma^2 \rangle)$.It is easy to show that $\Bbb Q(a)\subseteq Fix(\langle \sigma^2 \rangle)$ because $$a=\zeta+\sigma^2(\zeta)+\sigma^4(\zeta)+\sigma^6(\zeta)+\sigma^8(\zeta)\in Fix(\langle \sigma^2\rangle)$$
We khow that $[Fix((\langle \sigma^2 \rangle):\Bbb Q]=[G:\langle \sigma^2 \rangle]=2$ and if we show so that $[\Bbb Q(a):\Bbb Q]=2$ we have that $\Bbb Q(a)=Fix(\langle \sigma^2 \rangle)$, but how can i show that $[\Bbb Q(a):\Bbb Q]=2$. My first idea was to show that $a\notin \Bbb Q$ but we don't khow if $a$ is algebraic of $\Bbb Q$ and if $a$ is algebraic how can we show that $a\notin \Bbb Q$?
Comment: It follows from the fact that $a$ has exactly two conjugates (namely $a$ itself and $\sigma(a)=\zeta^2+\zeta^6+\zeta^7+\zeta^8+\zeta^{10})$ that $a$ is of degree 2 over $\mathbf{Q}$.
Comment: Sure you're right i ''ll change it.
Comment: Good. For extra credit, you can try and show that $\Bbb{Q}(a)=\Bbb{Q}(\sqrt{-11})$. Adapt the method from [here](https://math.stackexchange.com/a/299417/11619) :to find a quadratic equation satisfied by $a$ (and $\sigma(a)$).
Comment: Thank you very much it was very useful method.
Answer: What you want to show is that $Fix(\langle \sigma^{2} \rangle) \subset \mathbb{Q}(a)$.
Let's find with some calculus (which results to be a general approach to this type of problems with small cyclotomic extensions) the fixed field of the automorphism $\phi := \sigma^{2} : \zeta \longmapsto \zeta^{4}$.
A basis of the splitting field over $\mathbb{Q}$ is $\left\lbrace 1,\zeta,\cdots, \zeta^{9} \right\rbrace$ with the known relation $1+\zeta+\cdots +\zeta^{10} = 0$
If $\alpha = a_{0} + a_{1}\zeta + \cdots a_{9}\zeta^{9}, \hspace{0.3cm} a_{i} \in \mathbb{Q}$
Then
$$\phi(\alpha) = \sum\limits_{i=0}^{9}\phi(a_{i}\zeta^{i}) =  \sum\limits_{i=0}^{9}a_{i}\sigma(\sigma(\zeta^{i}))= \sum\limits_{i=0}^{9}a_{i} \sigma(\zeta^{2i}) = \sum\limits_{i=0}^{9}a_{i} \zeta^{4i}$$
Which results to be
$$\phi(\alpha) = a_{0} + a_{1}\zeta^{4} + a_{2}\zeta^{8} + a_{3}\zeta + a_{4}\zeta^{5}+a_{5}\zeta^{9}+a_{6}\zeta^{2}+a_{7}\zeta^{6}+a_{8}\zeta^{10}+a_{9}\zeta^{3}$$
Since $$\alpha = a_{0} + \cdots + a_{9}\zeta^{9}$$
We have that $\alpha$ lies in the fixed subfield if $\alpha = \phi(\alpha)$ if and only if $a_{1} = a_{3} = a_{4} = a_{5} = a_{9},a_{2} = a_{6} = a_{7} = a_{8} = 0$
(This follows if justified from the fact a linear combination of a basis representing the null vector must $0$ to all the coefficients)
Which translates into $K^{\sigma^{2}} = \left\lbrace a + b(\zeta+\zeta^{3}+\zeta^{4}+\zeta^{5}+\zeta^{9}): a,b \in \mathbb{Q}\right\rbrace$, which is indeed what we were looking for.

Show that $[\Bbb Q(a):\Bbb Q]=2$


Get latest transactions using Solana RPC

Question: I have looked a lot into RPC and WSS methods at the solana documentation but apart from the still under development blockSubscribe method (which doesn't work for most solana RPCs out there) I have found no way to get the latest transactions being done each block. Any clues on how to do this or services that provide an RPC that has blockSubscribe working?
Answer: The blockSubscribe endpoint was designed for exactly this case, so your best might be to setup your own node with this flag enabled. Your only other option will be to partner with a validator or RPC provider and get them to run a Geyser plugin, which can stream all transaction information directly to your server.
More info about Geyser at https://docs.solanalabs.com/validator/geyser
Answer: There is a few options for you depending on your exact problem:

onRootChange : This gets called whenever a root* is created and is most likely what you'll want.
onSlotUpdate : If you want to be super granular, this callback doesn't get just triggered when a new block is rooted, but instead gets called during the individual steps of block production, telling you when the first shred is received, when the block is processed, confirmed, rooted, etc etc. You can view the exact steps it returns here.

*Quick reminder on what root means in this context from the docs:

A block or slot that has reached maximum lockout on a validator. The root is the highest block that is an ancestor of all active forks on a validator. All ancestor blocks of a root are also transitively a root. Blocks that are not an ancestor and not a descendant of the root are excluded from consideration for consensus and can be discarded.


SharePoint 2013 limiting view on document in list based on department

Question: we have a document repository that has documents for multiple departments in one list. However I need to make it so the departments can only view there items. I have tried to filter view based on department, but it is not showing the results I want. In actuality it shows the same department no matter who you are.
Comment: Check out the posibilities of **Document Sets** (available since 2010)
Answer: <code><Membership  Type="CurrentUserGroups"><FieldRef Name="Department"/></Membership>
</code>
Here is something that you can try:

Add a new column (example:"My Department") of type "Person or group" to the list.
Create a SharePoint group for each department and set the department field in each item to a relevant Department sharepoint group.
Then you can change the view query to show items based on if the user is a member of the Department group using the membership tag as shown at the top.
Comment: But the [ME] filter works with **one** userId
Answer: Assume you have 4 departments.  Create 4 folders within your document library (one per department) and 4 SharePoint groups (one per department).  Populate the groups with users appropriately, then assign permissions to the folders using the groups you created.
Set the default view to show a flat list of files (ignoring folders) and each user's default view will then be limited to only the files to which they have access -- the ones in their department's subfolder.
This will also let you support cross-functional users who belong to more than 1 department and thus need to see files from 2 or more.


Catching a direct redirect to /dev/tty

Question: I'm working on an application controller for a program that is spitting text directly to /dev/tty.
This is a production application controller that must be able to catch all text going to the terminal. Generally, this isn't a problem. We simply redirect stdout and stderr. This particular application is making direct calls to echo and redirecting the result to /dev/tty (echo "some text" > /dev/tty). Redirects via my application controller are failing to catch the text.
I do have the source for this application, but am not in a position to modify it, nor is it being maintained anymore. Any ideas on how to catch and/or throw away the output?
Answer:  screen -D -m yourEvilProgram

should work. Much time passed sinced I used it, but if you need to read some of its output it could even be possible that you could utilize some sockets to read it.
[Added: two links, Rackaid and Pixelbeat, and the home page at GNU]
Answer: The classic solution to controlling an application like this is Expect, which sets up pseudo-terminals, does logging, and drives the controlled application from a script.  It comes with lots of sample scripts so you can probably just adapt one to fit your needs.
Answer: This is what I did in python
import pty, os

pid, fd = pty.fork()
if pid == 0: # In the child process execute another command
    os.execv('./my-progr', [''])
    print "Execv never returns :-)"
else:
    while True:
        try:
            print os.read(fd,65536),
        except OSError:
            break

Answer: I can't quite determine whether the screen program mentioned by @flolo will do what you need or not.  It may, but I'm not sure whether there is a logging facility built in, which appears to be what you need.
There probably is a program out there already to do what you need.  I'd nominate sudosh as a possibility.
If you end up needing to write your own, you'll probably need to use a pseudo-tty (pty) and have your application controller sit in between the user's real terminal connection and the the pty device, where it can log whatever you need it to log.  That's not trivial.  You can find information about this in Rochkind's "Advanced UNIX Programming, 2nd Edn"  book, and no doubt other similar books (Stevens' "Advanced Programming in the UNIX Environment" book is a likely candidate, but I don't have a copy to verify that).

Catching a direct redirect to /dev/tty


CryptoSwift with AES128 CTR Mode - Buggy counter increment?

Question: i've encountered a problem on the CryptoSwift-API (krzyzanowskim) while using AES128 with the CTR-Mode and my test function (nullArrayBugTest()) that produces on specific counter values (between 0 and 25 = on 13 and 24) a wrong array count that should usually be 16!
Even if I use the manually incremented "iv_13" with the buggy value 13 instead of the default "iv_0" and the counter 13...
 Test it out to get an idea what I mean.
  func nullArrayBugTest() {
    var ctr:CTR
    let nilArrayToEncrypt = Data(hex: "00000000000000000000000000000000")
    let key_ = Data(hex: "000a0b0c0d0e0f010203040506070809")
    let iv_0:  Array<UInt8> = [0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f]
    //let iv_13:  Array<UInt8> = [0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x1c]
    var decryptedNilArray = [UInt8]()

    for i in 0...25 {
        ctr = CTR(iv: iv_0, counter: i)
        do {
            let aes = try AES(key: key_.bytes, blockMode: ctr)
            decryptedNilArray = try aes.decrypt([UInt8](nilArrayToEncrypt))
            print("AES_testcase_\(i) for ctr: \(ctr) withArrayCount: \(decryptedNilArray.count)")
        }catch {
            print("De-/En-CryptData failed with: \(error)")
        }
    }
}

Output with buggy values
The question why I always need the encrypted array with 16 values is not important :D.
Does anybody know why the aes.decrypt()-function handles that like I received?
Thanks for your time.
Michael S.
Answer: CryptoSwift defaults to PKCS#7 padding. Your resulting plaintexts have invalid padding. CryptoSwift ignores padding errors, which IMO is a bug, but that's how it's implemented. (All the counters that you're considering "correct" should really have failed to decrypt at all.)  (I spoke this over with Marcin and he reminded me that even at this low level, it's normal to ignore padding errors to avoid padding oracle attacks. I'd forgotten that I do it this way too....)
That said, sometimes the padding will be "close enough" that CryptoSwift will try to remove padding bytes. It usually won't be valid padding, but it'll be close enough for CrypoSwift's test.
As an example, your first counter creates the following padded plaintext:
[233, 222, 112, 79, 186, 18, 139, 53, 208, 61, 91, 0, 120, 247, 187, 254]

254 > 16, so CryptoSwift doesn't try to remove padding.
For a counter of 13, the following padded plaintext is returned:
[160, 140, 187, 255, 90, 209, 124, 158, 19, 169, 164, 110, 157, 245, 108, 12]

12 < 16, so CryptoSwift removes 12 bytes, leaving 4. (This is not how PKCS#7 padding works, but it's how CryptoSwift works.)
The underlying problem is you're not decrypting something you encrypted. You're just running a static block through the decryption scheme.
If you don't want padding, you can request that:
let aes = try AES(key: key_.bytes, blockMode: ctr, padding: .noPadding)

This will return you what you're expecting.
Just in case there's any confusion by other readers: this use of CTR is wildly insecure and no part of it should be copied. I'm assuming that the actual encryption code doesn't work anything like this.
Answer: I guess the encryption happens without the padding applied, but then u use padding to decrypt. To fix that, use the same technique on both sides. That said, this is a solution (@rob-napier answer is more detailed):
try AES(key: key_.bytes, blockMode: ctr, padding: .noPadding)


How much can I expect to improve in 1 year?

Question: I am 51 yo, started cycling 2 months ago. I do about 80 km per week (in weekends). Currently my average speed over large distances (max distance I've done so far is 90 km) is around 22 km/h. On flat surface, 600 m distance I currently reach on average 33 km/h, but after about 300 m I lose speed. Two months ago I was doing about 30 km/h. My peak speed is about 41 km/h, for very short distances. Do I have any chance to reach an average speed of 40 km/h over 600 m within one year?
Comment: There's only one way to find out:  keep riding and see where you are in a year.  And don't worry about how fast you're going - you've only been riding two months. Right now?  Just keep riding, enjoy the experience, learn, and let the level of performance take care of itself.
Comment: That's a pretty good pace for an older person who's only been at it for a couple months.  You should look for a cycling group in your area. There's usually groups for all levels of bikers from beginners all the way up as high as you want to go. Your speed is going to be affected somewhat by what bike you have, but mostly your fitness level.
Comment: Just keep going. Increase the distance steadily to build up stamina. Persevere and speed will be the by-product!
Answer: Without knowing any more detail, the goal is probably achievable but you won't do it by riding harder, you need to train smart(er).
Given you just started cycling, if you have not had any coaching, you are probably close to fit enough to do it with improved techniques. You should therefore focus on training, not riding.  If you train to ride, rather than ride to train, you will become a stronger rider.  How much training vs riding is up to you - no point spending all you time training, especially if you don't enjoy it as much.
I suggest getting involved with a local cycle group, and maybe seek advice from a cycling coach. If you don't want to use a coach, look around the internet for training ideas and plans.  Be careful not to overdo it.
Comment: Thanks for advice. I didn't have any coaching, I am just riding by myself and rarely using the exercise bike for sessions of 1 min or 5 min in the evenings.
Answer: Perceptively, its always as hard to ride.   So one of the best tools is accurate record keeping to show your improvements over time.
Personally I use Strava on every ride to record my route and times.  This lets me compare my times on marked segments for improvement.  Strava has an app that works on most fancy-phones.  You can also get a chrome plugin called  Elevate that shows cumulative graphs for distance/elevation over the year or for the last N days.
Unless you've gone full-MAMIL and bought all the kit, there's a good chance you're still working out what equipment works for you.  Keep revising, and don't hesitate to try different ideas for gear.
So how much improvement should you expect?  More than you'd get for doing nothing and sitting on the couch all day - and that's all that matters.
Comment: @Nick_F my point about strava is to ride for personal improvement.  In the options, set it to display "My times" rather than the default leaderboard.   I can do a climb in 22 minutes, hoping to get under 20, but the locals can do it in under 12.  I don't care about them, I care about my improvements only.
Comment: I understand, I do the same. I took some of the segments over 20 times. I am checking the plot with my results and I check if there is a trend toward improvement. So far is too early to see a clear improvement for me, some days I am faster, some days slower, but the best times are all in recent history. On the longer trips, I get lots of PR (sometimes over 100). But I find the biggest motivation for me is when I have a clear goal (i.e. achieving x time on y segment or having an average speed of x in 20 km), rather than general improvement, which is not defined.
Comment: Thanks for info. I installed Strava on my phone and I selected some nearby short segments where I try to improve my position. So far they have not been visited by KOM hunters and I have some chances at stealing some KOM's. On the shortest segment, 310 m I am currently at equal place with KOM, out of 800 riders, with a time of 31 seconds. On a longer segment, 570m I am on position 3 out of 630, with a time of 1:00. I've been helped by some wind. I am not wearing yet any MAMIL stuff, I don't have yet cycling clothes or clipless shoes. I have a nice, older Giant OCR bike and I am pleased with it,


Water pressure low after hose was left on overnight

Question: The water pressure inside my house went way down and stayed down after the hose was left on overnight.  It's been a while now and the water pressure is still low (useable but low).  The air pressure on the pump hovers between 40 and 50psi and we are served by well water.  I hope there was no permanent damage done by leaving the hose on for that long.  Anyone have any suggestions?
Comment: Does this mean the pump isn't shutting off? An easy way to help isolate is to close the valve to the rest of your house. If it comes up to pressure and shuts off right away, you have something else using water (could be a leak). If not, I'd suspect as @Bob suggests the well is low. You might just want to try shutting off the pump power for a while to give your pump a break (and let the well catch up).
Comment: The pump is definitely shutting off.  I'm going to try and not use the water for a day or so and see if it can catch up.
Answer: I'd guess that the recovery rate on your well is sufficient for your daily use, but not for the extended used that occured with the hose.  As a result, the water level in your well has probably dropped to the point that the intake tube isn't completely submerged, so it's drawing less water.  If you can reduce your water usage for a few days, it will likely recover.


Chromebook can't download to Google Drive because Hard Disk is full?

Question: I recently had to powerwash my Chromebook to fix a keyboard issue I was having and all my files were deleted as a result.  I have downloaded 18GB of files to google drive on my chromebook, and only 268MB of Downloads and Browsing data to the hard drive.  The google drive files are not set to be available offline, but are anyways.  My chromebook says that I only have 491MB of space left on the hard drive, and I can't download a 200MB file to my google drive (even though literal terabytes of data remain).  The chromebook is heavily locked down by my Administrator (who provided the chromebook), so I can't access some critical parts of the settings, but I absolutely cannot figure out why I can't download things to my google drive anymore.  I've tried clearing up space but that fixes nothing.  I'm afraid that when I powerwashed it, the files weren't actually deleted but aren't able to be seen by the file explorer.  If this is the case, I don't want to reset it again.  I can't even save screenshots to show what's happening.  There is a recent section in the file explorer which is read-only that shows several GB of data, but I think it's just a display of recent files and not a storage place.
How do I fix this?  It's basically rendering my chromebook useless for my purposes.
Comment: Speak to your Administrator.
Answer: Based on what you've described, if I were in your situation, unfortunately I would ask my administrator. Without administrator access, I am not sure what other avenues are available


How would I number my measures for my solo?

Question: How would I number the the top line, since the first measure is basically 1/2 of a measure, would I still put 1? The measure or 2 after the 2-4 are half measure, but two half measure make one so would I just put 5 for both combined or 5 and 6. I'm very confused here, I'd appreciate if anyone had an answer for this.
Comment: I am voting to reopen because I think it's clear that additional confusion is caused by the repeat symbol appearing in the middle of a bar, and that is not addressed by the proposed duplicate.
Comment: In this case, the repeat symbols are not bar lines. Pickup bars are not numbered. The first full bar is 1.
Comment: The rehearsal letters are your friend when the bar numbers need so much explanation. "We'll star two bars before (A) without doing the repeat" = OK. But "We'll start at bar 23" = Huh?
Answer: As you note, the first "measure" isn't a whole measure — this is called an anacrusis or a pickup, and it doesn't count as the first measure.  If you have to give it a number it will be 0.
The next thing is that multi-measure rest, this counts as the first three measures 1, 2, and 3.
The fourth measure starts with a minim/half rests. But, the repeat sign doesn't coincide with where a bar line would normally occur, so the first two notes of the solo are also in measure 4.
A similar thing happens an the end of the first repeated section.  The repeated sections ends with the first half of measure 12, and the second half comes afterwards.
Rehearsal mark A is at the start of measure 13.

NB: The piece runs off the side of the image, so I had to guess about how many measures are off-screen.


Blockchain shows a confirmed order still "unspent". How do I reclaim Bitcoin thru Coinbase, so I can place order again

Question: I placed an order thru Coinbase using Bitcoin to the address the vendor provided at checkout, and the transaction was confirmed.  However, now several days later, the Blockchain shows the Bitcoin "unspent". I never got the confirmation email from the vendor.  If the vendor doesn't spend it, due to a loss of the order or wrong wallet address, will Coinbase refund my Bitcoin, so I can try to place my order again?
Answer: When a transaction output is labelled as "unspent" it means that it is still available for spending. Assuming that the transaction output went to your wallet, it means that your wallet still has that unspent available for spending.
Answer: Once a transaction is confirmed, it is irreversible. It can only be touched by the recipient, in this case the vendor. You need to contact them.


Are enlightened beings necessarily omniscient?

Question: Is it necessary that every enlightened being is an all-knowing person? Are there any grades of enlightments according to scriptures?
Comment: Actually there are many grades of enlightenment. In the highest form of enlightenment (7th one) in which the whole universe appears as I-consciousness, one becomes omniscient.
Comment: Yup dear. Actually one when realized only Shiva aspect he has no powers but when one realized his Shakti aspect as well one becomes omniscient, omnipresent etc. After all Jiva is just Shiva under bondages.
Comment: Read this simple but beautiful article about enlightenment by Om Swami: http://omswami.com/2018/04/enlightenment.html
Comment: Good question, I'm tempted to write an answer but I've forgotten English. Will write an answer when will recollect forgotten English. Gautam Buddha had became omniscient.
Comment: @Rohit. I asked this question because of you :)
Answer: There is no evidence that one becomes omniscient - Ramakrishna Paramahamsa, Ramana Maharishi being some examples - although they are able to read minds.
An excellent summary of different states of Samadhi by Ramana Maharishi is below:

Question : What are kevala nirvikalpa samadhi and sahaja nirvikalpa samadhi?
Ramana Maharshi : The immersion of the mind in the Self, but without its destruction, is kevala nirvikalpa samadhi. In this state one is not free from vasanas and so one does not therefore attain mukti. Only after the vasanas have been destroyed can one attain liberation.
Question : When can one practise sahaja samadhi?
Ramana Maharshi : Even from the beginning. Even though one practises kevala nirvikalpa samadhi for years together, if one has not rooted out the vasanas one will not attain liberation.
Question : May I have a clear idea of the difference between savikalpa and nirvikalpa?
Ramana Maharshi : Holding on to the supreme state is samadhi. When it is with effort due to mental disturbances, it is savikalpa. When these disturbances are absent, it is nirvikalpa. Remaining permanently in the primal state without effort is sahaja.
Question : Is nirvikalpa samadhi absolutely necessary before the attainment of sahaja?
Ramana Maharshi : Abiding permanently in any of these samadhis, either savikalpa or nirvikatpa, is sahaja [the natural state]. What is body-consciousness? It is the insentient body plus consciousness. Both of these must lie in another consciousness which is absolute and unaffected and which remains as it always is, with or without the body-consciousness.
What does it then matter whether the body-consciousness is lost or retained, provided one is holding on to that pure consciousness? Total absence of body-consciousness has the advantage of making the samadhi more intense, although it makes no difference to the knowledge of the supreme.
Answer: I am answering acc. to Sri Vainava (VisishtAdvaita) Sampradayam

The Vedas exclaim that having created the vast universe, the Supreme Brahman holds it with perfect precision, pervading each and every aspect of it in its entirety. This truth may be accepted at an intellectual level by many of us, but to experience it as the absolute truth is the essence of Brahma Jnana or enlightenment[1]

This Brahma Jnana is possible in two ways - Enlightenment from practice of Bhakti Yoga and Enlightenment via attainment of Brahmānandam (or Moksha).
What is Brahmānandam?
It is Permanent Realisation (Moksha) exemplified by equality of experience (Sayujya) in eternal, indescribably perfect fusion of seshAtva and Paratantriya to DivyaThampathiyAr (i.e., Divine Couple, namely, Sri Maha Lakshmi and Vishnu). jivAtmas that are given Moksha by srimannArAyaNa attain to excellence in Paramapadam (or Vaikuntam) and are blessed with this state of cognisance.
Enlightenment via Bhakti Yoga
It is possible as a consequence of the practice of Bhakti Yoga to attain Brahma Jnana. Azhwars, in their verses, describe their experiences of Brahma Jnana to the extent that language can facilitate it.
Having given the two grades of enlightenment, what remains is:

Is it necessary that every enlightened being is an all-knowing person?

No. It is possible to attain Brahma Jnana without attaining Siddhis such as Omniscience - Brahma Jnana attained through Bhakti Yoga can be of this kind.
Edit -
Source: For definition of Enlightenment, I used the Hindu article. OP did not define the term himself, I chose to exercise this liberty. I believe this is the widely accepted definition. The body of the answer draws primarily from Naalayira Divya Prabandham
Comment: the answer consists of a newspaper citation and totally unsourced material.


how to find out the apache version installed in ubuntu?

Question: how to find out the Apache server version installed in Ubuntu 14.04?
Answer: Open the terminal and type:
apache2 -v

-v  Print the version of apache2, and then exit.
Answer: From the terminal you can enter: (lowercase -v)
apachectl -v

or to get even more compile info on Apache enter: (uppercase -V)
apachectl -V

of course as mention by @karel you can also use apache2 instead of apachectl... just giving an alternative. This worked for me in Ubuntu 18.04 and I'm using Apache 2.4.37.
Comment: @Ali Çarıkçıoğlu, well for one thing karel's solution didn't work for me at all with Apache 2.2.22 (not pre-installed). Both solutions from god_is_love were very useful for me.
Comment: this was a solved question from march 2015. why and how is your alternative answer any useful ?
Comment: I guess if you run the same command twice, you get a different result?
Comment: One is a lowercase `v` and the other is an uppercase `V` which could be different levels of verbosity for `apachectl`, but I can't find any indication these flags exist in the manpage.
Comment: This solution also helped us (and the first didn't). Admittedly, this isn't on ubuntu 14.04, but the title didn't disclose that, and we ended up here nonetheless.
Answer: if you have PHP installed with you apache2, you can find it in $_SERVER variable or with phpinfo() function:
<?php
var_dump($_SERVER);
phpinfo();

returns (on my computer):
'SERVER_SIGNATURE' => string '<address>Apache/2.4.29 (Ubuntu) Server …</address>
'SERVER_SOFTWARE' => string 'Apache/2.4.29 (Ubuntu)'

# and in phpinfo arrays:
apache2handler
Apache Version  Apache/2.4.29 (Ubuntu)


Can I Use Sickening Grasp [Reserve Feat] During a Full Attack with a Two-Handed Weapon?

Question: Could a duskblade with vampiric touch as his first third level spell take the reserve feat sickening grasp, full round attack with his two handed weapon, then take a hand off and touch attack with sickening grasp? The reserve feat states it is a touch attack, not a standard action, so I believe this should work as a nice debuff for two or three rounds using your lower base attack shot.
Comment: A tip: when asking questions, make the title clearly indicate what the question is. This title is just two nouns with no verb, which doesn't convey anything useful to people reading the list of questions.
Answer: No.
Complete Mage states:

Each reserve feat's primary benefit is a supernatural ability usable at will. Unless stated otherwise, it requires a standard action to activate and does not provoke attacks of opportunity.

The touch attack is merely a part of using the feat. Similar to Inflict Light Wounds allowing you to cast the spell, and then make a touch attack - as a part of the spell. Activating the feat itself, as a supernatural ability, is a standard action, giving you a touch attack as part of that standard action.
Note: It would be allowed if someone/something gave you an extra Standard Action, like the Belt of Battle. Taking your 'off-hand' off a two-hander is considered a free action.
Comment: Right you are, to bad it would have been a sweet one two punch.
Comment: @Nathtfm What also could be 'nice' would be to ask your DM if you could channel the Reserve Feat through your weapon. It would purely be a house rule - but would not be game breaking at all.


Pseudo-random orthogonal matrix generation

Question: A little while back, J.M. suggested using the Stewart algorithm for generating $n$ by $n$ pseudo random orthogonal matrices in $O(n^2)$ time. He further noted that this methodology is implemented in Nick Higham's matrix computation toolbox (matlab). Now this package contains a bunch of .m files. Could anyone direct me to which one implements the pseudorandom orthogonal matrix generator? Alternatively, would anyone know of a R implementation of this algorithm?
Answer: It's in the Test Matrix Toolbox, not the Matrix Computation Toolbox. The M-file qmult.m (premultiplication by a Haar-distributed pseudorandom orthogonal matrix) can be found here or here.
Comment: Thanks alot (both for the clever initial suggestion and for the folow thru).
Comment: No problem, kwak; remember only that it does premultiplication, though modifying the algorithm to do postmultiplication shouldn't be too hard.
Comment: M.:> it should be okay: i only need Q (i.e. qmult(eye(p)))


Want to build a digital picture frame

Question: I've searched on the message board and can't find an answer to my questions, or at least one that definitively answers it. Also, in case it's important, I am a Pi Newbie. Just got one, and still climbing the learning curve.
So, I want to build a digital picture frame for my girlfriend. I have a Pi 3, and an old LCD monitor. A ViewSonic VX2035wm, to be specific. I looked up the specs, and it says it has a TFT active matrix display.
I have read some threads where people talk about where you can run into troubles trying to connect LCD screens, but nothing so specific as "you can't use TFT and connect to Pi without an adapter". I don't want to tear apart this monitor to find I can't connect, but I also don't want to order a screen and still wonder if I could've used it instead.
So, can anyone help me with my conundrum?
Answer: The specification for that monitor says it has a DVI input. You just need an HDMI to DVI cable. The Pi should detect the monitor fine.

Want to build a digital picture frame


Meaning of "sporting"

Question: In the phrase "On devices sporting the needed sensor, heart activity can be sampled," the word "sporting" obviously means "equipped." But in which cases the word "sporting" could substitute "equipped"?
Comment: heart activity can be sampled??Who wrote that? to sport something can mean to feature it. Probably a botched translation.
Answer: When "sporting" is substituted for "equipped," I see it most often used in product advertisements or reviews. You might see something like "Renault's latest car model is sporting a heated steering wheel" as that would be an uncommon and notable feature. However, it would be highly unlikely that someone would write "Renault's latest car model is sporting a steering wheel" even though it's technically true.
Some examples:

Samsung's Galaxy A7, sporting a three camera setup at the
back...
Kawasaki Ninja H2, sporting a 998cc inline-four-cylinder and the
first supercharger on a production motorcycle...
Raspberry Pi 4 vs Raspberry Pi 3, The new model sports four USB
ports, with two of them sporting USB 3.0. This is a notable upgrade
over the last model, which only featured four USB 2.0 ports.

In the case of a heartbeat sensor, that is still something that is uncommon on a phone, and not always present on a smart watch. It's much more common on a fitness watch but it's still feature you would have to specifically look for on any given model.
Answer: I'm completely convinced that the word "sporting" is a typographical error, and it should be supporting
Comment: _Sporting_ can mean _wearing_ (some distinctive item of dress), so it could conceivably mean _displaying_ here, but it seems unlikely unless the rest of the passage is written in a semi-humorous style.
Comment: The text is contained on the Wikipedia page for Wear OS, which is an operating system for smart watches and other 'wearables'. I found a medical paper in Clinician Reviews entitled 'Sporting an Old Lesion'.

Meaning of "sporting"


What does "we're all bozos on this bus" mean?

Question: What does "we're all bozos on this bus" mean in the following sentence?

This reminds me of my lovely old German teacher. One of the first things he told us was "we're all bozos on this bus."
Comment: bozo the clown is very famous in the usa. was the German teacher a German teaching math or an American teaching German?  https://en.m.wikipedia.org/wiki/Bozo_the_Clown
Comment: Where did this quote come from?
Answer: http://www.goodreads.com/quotes/144569-we-re-all-bozos-on-the-bus-so-might-as-well
(https://en.wikipedia.org/wiki/Wavy_Gravy)
Here's an interpretation:

But my all-time favorite Wavy-ism is the line above about Bozos on the bus, one he repeats whenever he speaks to groups, whether at a clown workshop or in a children's hospital. I have co-opted the phrase and I use it to begin my workshops, because I believe that we are all bozos on the bus, contrary to the self-assured image we work so hard to present to each other on a daily basis. We are all half-baked experiments-mistake-prone beings, born without an instruction book into a complex world. None of us are models of perfect behavior: We have all betrayed and been betrayed; we've been known to be egotistical, unreliable, lethargic, and stingy; and each one of us has, at times, awakened in the middle of the night worrying about everything from money to kids to terrorism to wrinkled skin and receding hairlines. In other words, we're all bozos on the bus.

http://www.feminist.com/ourinnerlives/inspiration_lesser3.html
Answer: "We're all bozos on this bus" is subject to interpretation, but one way of explaining it is:

None of us is immune to the surrealness of life.

The phrase "We're all bozos on this bus" is the title of a Firesign Theater album from 1971, and a line of dialogue from the album.  Firesign Theater was a comedy group that made surrealist audio recordings.
If you want to listen to the album: https://www.youtube.com/watch?v=lmWFrMq3qNY.  The key quote comes at about six minutes in.
"Bozo the Clown" was a popular culture icon in the U.S. long before anybody was talking about popular culture.  Then Firesign played with it.  Here's what Firesign said about Bozo in an interview:

B.O.Z.O. is the Brotherhood of Zips and Others. Bozos are people who band together for fun and profit. They have no jobs. Anybody who goes on a tour is a Bozo. Why does a Bozo cross the street? Because there's a Bozo on the other side. It comes from the phrase vosotros, meaning others. They're the huge, fat, middle waist. The archetype is an Irish drunk clown with red hair and nose, and pale skin. Fields, William Bendix. Everybody tends to drift towards Bozoness. It has Oz in it. They mean well. They're straight-looking except they've got inflatable shoes. They like their comforts. The Bozos have learned to enjoy their free time, which is all the time.

I will explain "goes on a tour" in case you're not familiar with that concept.  The comedians are making fun of people who get on a tour bus and visit a sightseeing landmark in a group, with glib explanations provided by a tour guide.
Here's an example of someone citing the line in order to explain how surreal the Trump phenomenon feels to him:

5 Aug. 2016
Dear Friends and Patriots,
A long time ago there was a comedic group called Firesign Theater.  Firesign Theater put out a series of long-playing albums (that's records on vinyl for you digit-heads) that were part fantasy, part social satire, and part wild imaginings of some truly twisted minds.  To call the albums bizarre is to give them only partial credit.  For those of us who were sort of young at the time, they were completely delightful exercises in mental anarchy.   I was in the Navy at the time and my friends and I used to memorize and quote entire routines from the Firesign Theater albums.  When we were together and bouncing lines off each other with shipmates present who hadn't been properly indoctrinated the effect was much like speaking in tongues.  Unless you'd heard a Firesign Theater album a few times the effect was probably unsettling.  Think of a bunch of young guys spouting nonsense at each other, laughing like hyenas, and obviously understanding each and every phrase.   Yeah, it was a strange time.
I'm not sure those albums are available anywhere today, which is a great pity.  But . . . I do have a book that was released in the late '70s; a transcription of all the Firesign Theater albums.   I count myself fortunate because recalling and re-reading those skits helps me today.  Sometimes they serve as a frame of reference for current events most of you might consider completely irrational; beyond the pale of sanity.
The title of this article is also the title of the fourth Firesign Theater album.  The skit by that name centers around the conversations of a group of people who are all dressed up and on a bus headed for a clown convention.  I won't start quoting here because it's only tangential to the actual subject at hand.  Suffice it to say events of the past week or so have dredged the entire album out of the recesses of my mind.  Call me strange, if you wish.
This past week I've felt as if I were a clown on the Bozo bus.  The conversations I've heard emanating from my TV are downright bizarre.  The utterances of the presidential candidates have become inane and possibly insane babble.  Are we all Bozos on this bus, or have we somehow stepped through a worm hole together and are now occupying a parallel universe?


The focal chord that cuts the parabola $ x^2 = -6y$ at $(6, -6)$ cuts the parabola again at $X$

Question: The focal chord that cuts the parabola $x^2 = -6y$ at $(6, -6)$ cuts the parabola again at $X$. Find the coordinates of $X$.
I have been going insane someone please help me :(
Answer: HINT
Compare the equation with $x^2 = -4ay$ and find the coordinates of the focus.
Write the equation of the chord joining the two points (the focus and (6,-6)).
Solve the equation of the line with the parabola to get the point(s) of intersection.
Shorter solution :
You could find the coordinates of the focus and write the equation of the parabola in parametric form $(2at, -at^2)$.
After that, write the equation of a general focal chord joining the focus $(0, -a)$ and the point on the parabola $(2at, -at^2)$.
Plug in $(6,-6)$ into the equation and then solve for the value(s) of the parameter $t$. To get the point, substitute $t$ into $(2at, -at^2)$.


Origin of T'Challa the Black Panther's creation and Stan lee and Jack Kirby influences on creation of the character

Question: What was the inspiration behind the creation of T'Challa the Black Panther? what influenced Stan Lee and Jack Kirby when they came up  the character?
Answer: Possibly unsurprisingly, given Stan Lee's history of promotion occasionally trumping truth, it's disputed.

The origin of the idea for the character was disputed by both Kirby and Lee. Jack Kirby claimed sole credit for the creation of the character in The Comics Journal #134, from February 1990, stating that a realization that there were no black characters in his comics demanded some be added for "human reasons". Stan Lee claims the character was created by his desire in the mid-60s to include more African and African-American characters in Marvel Comics. While there is no documentation showing which version of the creation is closer to the truth, by 1966 Kirby is thought to have been largely plotting the book on his own and was having to explain the stories to Lee when the pages arrived in the Marvel offices, as had happened a few issues prior with the Silver Surfer in The Fantastic Four #48 (March 1966). In a 1968 interview Lee stated:

Some artists, such as Jack Kirby, need no plot at all. I mean I'll just say to Jack, 'Let's let the next villain be Dr. Doom'… or I may not even say that. He may tell me. And then he goes home and does it. He's so good at plots, I'm sure he's a thousand times better than I. He just about makes up the plots for these stories. All I do is a little editing.

In an interview, Kirby shared the same genesis as Lee, "I came up with the Black Panther because I realized I had no blacks in my strip. I'd never drawn a black. I needed a black. I suddenly discovered that I had a lot of black readers. My first friend was a black! And here I was ignoring them because I was associating with everybody else."
Roy Thomas has made claims that support Lee's version of events, while Kirby was supported by his wife and prior artwork. In 1963, they included a black character, Gabe Jones, in the ensemble cast of Sgt. Fury and His Howling Commandos, and Lee encouraged artists to include black characters in crowd scenes. In a 1998 interview, Lee explained his motivation: "I wasn't thinking of civil rights. I had a lot of friends who were black and we had artists who were black. So it occurred to me... why aren't there any black heroes?" Soon after Black Panther was introduced, Marvel also added two more recurring black characters: Jill Jerrold in Modeling with Millie, and Bill Foster in The Avengers.

Origin of T’Challa the Black Panther’s creation and Stan lee and Jack Kirby influences on creation of the character


Testing faulty fibre network

Question: As contractors linked the main comms with 3 sub-comms location with OM3 fibre I configured main switch Netgear GS728TS using three transceivers Netgear AGM731F, configured switches that will be used on it other end ( GS110TP) and then connected everything to fibre patch panel. Well nothing is happening. I tested both cables I am plugging to fibre patch panel - all fine, transivers are fine either.
I got back to contractors but they are quite convinced that all should be fine. Is there any diagnostics, checks, test I can run to check if cabling is flawless ? I dont want to force them to site if there is something tiny and obvious preventing connectivity.
Answer: Assuming that you can log into the managed Netgear switches you should be able to use the internal utility to get information about the relevant ports.  See Page 256 of the linked switch software admin manual.
You should be able to get much more detailed information about the relevant ports like their physical status, etc using the management interface from Netgear.  If the fibre cables you mentioned are using the SFP ports you may want to verify that the cables are compatible with all interconnected networking equipment, some may not be.
Comment: Thanks for the manual. Switch back end is showing as off at the moment. The transceivers look like are compatible with OM3 and this is what should be installed. I am really getting confused here and I dont want to act to hard on them if there is fault on my side.
Comment: To clarify, is it possible to do a cable test using the switch management interface?
Answer: OK, it might be obvious solution for someone or it might be actually helpful for other. We found solution by dismantling the splice drawer - Tx/Rx runs where connected to wrong ports all that have to be done is to unplug fiber runs inside and swap them around.

Testing faulty fibre network


How to add custom class to a  fileds on the renderable array of user_profile_form

Question: I have a requirement to add a class to  ul  li  on the user_profile_form edit page on admin side.
Using Hierarchical Select Taxonomy module regions are listed on this form.The purpose is to modify  the listing of the regions by adding different classes for the regions based on the taxonamy id.
Answer: You can do it 2 ways. One is to modify the element attributes, like this:
$form['textfield'] = [
  '#type' => 'textfield',
  '#attributes' => [
    'class' => [
      'ul',
    ]
  ],
];

Or, another way, wrap the elements with '#prefix' and '#suffix'.
$form['textfield'] = [
  '#type' => 'textfield',
  '#prefix' => '
',
  '#suffix' => '
',
];

I would use the first preferably when I can.


Can Changelings use oneiromancy for space travel?

Question: For example, if Changeling is on Mars, can they traverse Dream Roads to go to Earth?
Answer: That's not what oneiromancy does, and that's not where Changelings are.
Oneiromancy is the ability to travel through the realm of dreams. You can either get there by lucid dreaming (the Gate of Ivory) or by finding Dreaming Roads in the Hedge (the Gate of Horn). It's not a means of moving about reliably through the physical world.
Further, Changeling: The Lost takes place in the Chronicles of Darkness setting, on an Earth similar to our own (with some secrets and surprises). In the standard version of the game, there are no extra-planetary residents, so there would be no changelings on Mars, nor would there be dreamers on Mars for them to travel to.


Is there still any potential for a major new popular music genre to appear?

Question: I'm of the generation that had their teenage years in the 90s. At that time, the mid-70s seemed musically very different - who could imagine a world with no techno and no hip-hop?
The mid-90s are now as far back in the past as the mid-70s were then. And though there have been shifts in the balance of genre popularity and some new fusions (the increasing crossover of techno/dance and mainstream hip-hop for one), It seems to me that there's been nothing distinctively new since the 90s. There have been revolutions in how we make, buy, and listen to music - but not so much development in what that music sounds like.
The 60s was full of change. The 70s had funk, disco, and punk; the 80s, hip-hop and synth pop. The 90s witnessed an explosion of dance and electronic styles. Since then it seems to have been evolution rather than revolution. I'm worried that I won't ever have an opportunity to shout "that's not real music" to a crowd of youngsters listening to something that wasn't around when I was young!
Are we likely to hear anything else really new in our lifetime? Or is pop done?
EDIT: Just saw this article  claiming that there were three "music revolutions" - in 1964, 1983 and 1991. (It also mentions changes in harmony in the 1970s from funk, soul and disco). Maybe what I am wondering is, could there be another music shift comparable to those, and where might it come from?
Comment: Yeah, the music the kids listen to these days isn't noisy _enough_. That's got to be a first...
Comment: @MeaningfulUsername it seems they *are* annoying us oldies then, with their bland watered-down stuff!
Comment: We've always had fusion. Most genres have been a fusion of previous genres.
Comment: Hm, so it seems. And maybe this is more efficient even; a more annoying way of being annoying. I'm shaking my cane in the general direction of youth everywhere!
Comment: I think UK satire site The Daily Mash had the best answer to this question: [Modern youth not starting a subculture unless they get paid for it](http://www.thedailymash.co.uk/news/society/modern-youth-not-starting-a-subculture-unless-they-get-paid-for-it-2014032184876) - "Teenagers are hinting at something 'really big' possibly called 'Snung' which over people 30 cannot relate to on any level..." "But first we need a cash injection to get our subculture through the development stage"
Comment: @user568458 - ahh, then the New Music ought to be called Kickstarter, I guess. What happened to sweating for years in loud, smoky, seedy clubs to learn your craft? Way too much instant gratification & entitlement syndrome. More Rock Star™  than Beatles, to my mind ;)
Comment: Fusion - combinations of styles. That's probably some of what we're going to see.
Comment: Techno and Hip Hop started in the 70's. Bands like Kraftwerk were the forerunners of techno. Punk band The Clash helped to propel Hip Hop into the mainstream in the late 70's by booking Grandmaster Flash and the Furious Five as the support act for their shows in New York (the crowd were admonished by Mick Jones for booing Grandmaster Flash).
Comment: @JamieTheBastard As I understand it, Hip-Hop as an identifiable musical movement was *very* localised / small scale until '77 or so, and even then it was a couple more years until 'Rappers Delight' came out and Hip-Hop started to show its face to the world. Kraftwerk were very much in the vanguard of techno... it's a little while before the rest of the world caught up, I think. The references to Flash supporting the Clash I can find mention 1981..?
Comment: Please note I am marked for deletion so may not be around to accept any answer; if so, so any bonus will be limited to whatever is awarded automatically: http://stackoverflow.com/help/bounty
Answer: First of all (this is a personal gripe), 'pop' isn't a genre of music. It's short for 'popular' and therefore, by it's very nature will keep on inverting itself. What was 'pop' (popular) in the 50's isn't 'pop' (popular) now.
As far as genres are concerned I think that absolutely yes there will be more coming along. I think today's 'kids' are living in a era of music where 'bland' seems to be popular. I'm agreeing with @Meaningful Username here - our music (I'm a child of the 70/80's) used to scare our parents (look up satanic lyrics in heavy metal) but now 'our' music seems to scare the children !
There doesn't seem to be much 'edgy' music, it's all too 'nice' and 'safe'. The same thing happened in the 60's with flower power and hippies and what happened ? Punk - that really shook things up !
So, yes, there will be more genres and (you need to get ready for this) we older people probably won't understand how the new genres are even music but that is exactly what the kids will be looking for.
Having said that, my age group (30's - 40's and beyond) are far more open to new musical styles than my parents and previous generations were.
Comment: Don't get lost in the semantics, pop music is more than "whatever is listened by many". Yes, "pop" is short for popular, but that doesn't mean that everything popular is pop, or that you can't produce pop music unless the masses know you. Pop music has been around for a while now and has developed distinct patterns. With this in mind, pop is objectively a style and/or genre, beyond whatever the name implies. Today, there's a distinction between "popular music" and "pop music".
Comment: @JCPedroza - completely agree. It's not going to stop me avoiding music classified as 'pop' though ;)
Answer: Yes, of course. What is the popular genre changes quite a bit from decade to decade. Sometimes quickly, sometimes not.
We also keep inventing new genres, as well as a seemingly infinite range of minute sub-genres, so the pool of options keeps increasing as well as to what will be the next 'pop'ular one.
There's no real argument as to why we'd not stop creating new musical genres. Humans have been doing it since they've invented music.
That said, perhaps the broad, universal trends aren't as noticeable. Up until the early 2000s, most pop music was heavily influenced by the media industries. The labels, radio stations, and MTV has a pretty strong monopoly on dictating what is popular and what is not.
As of the 2000s, the industry went through immense changes and music is now spread in so many more ways that it's become much less centralized. As such, the large decade-spanning monolithic genres have given away to a much more fragmented popular music landscape.
There still a lot going on, we just see it a lot differently than we did in, say, the 80s.
UPDATE:
On second read, perhaps I misread the question a bit. I think if we're saying 'major genre' being defined by a huge marketshare, then perhaps the answer is 'no'...we may not have any more major genres of pop music like we did in the period from the 50s-2000s. The reason for this (I theorize) is that the concept of 'major popular music genres' depends on a highly centralized media industry to promote them. When what you listed to was primarily dictated by the record and radio industry (and later, MTV), they had the ability to take a few genres and market them like crazy and essentially 'force' the status of 'major genre' on the marketplace.
But that era is over so perhaps we won't see such 'major' genre shifts as we did before (not that the industry isn't trying...their stake in the online streaming industry is a sign of that...)
Comment: I'm not thinking that we'll never get *anything* new - there definitely have been plenty of little sub-genres springing up, as you say. But there were at least four or five decades of relatively rapid major shifts in the second half of the last century. Since then, haven't things been slower? Your point about the more fragmented industry / consumption of music is a good one and that may well be one of the reasons for less dramatic wholesale shifts.
Comment: Other reasons that something dramatically new might now be harder to come up with : we've had a few decades now of quite intense global communication which has given opportunity for many of the cross-cultural inspirations that could happen *to* happen. Technology may also be a factor - we had the electric guitar, the synth, and the turntable, then the computer... then what? There may well be another big trigger (which could be another computer tech development) but I'm interested in what it might be....
Answer: To reference Lenny Bernstein in his Norton Lectures, as far as we can push tonality (namely, the number of possible tones in a given octave, currently 12) to the limit by somehow dividing the intervals into smaller and smaller chunks, we can get pretty bizarre music.  Now I'm speaking on classical music terms, but this decomposition of the traditional 12-notes-in-an-octave system into, say, 13-equivalent-intervals-in-an-octave system, can have an impact on today's modern electronic (and I mean electronic in the sense of Stockhausen and the likes) music. I was reminded that maybe it was Edgard Varèse who was involved with this, having been able to produce music with intervals smaller than the traditional half step.
Comment: To simply think of dividing the octave into smaller chunks seems a limiting way to look at the possibilities of tonality - after all, the frequency scale is continuous, so there is always an *infinite* range of notes to choose from; the trick is to find some that sound good together! That said, it is an exciting idea that there might be more evolutions in the tonality of popular music; there were certainly plenty in the last century, and I'm sure that there are many more palatable possibilities.
Answer: When I was a kid
[don't ask, long time ago…  ...ok, I admit, in the early 70's]
we were far too busy listening to the radio & trying to emulate the look by practising in the mirror with  plywood guitars with copper wire strings to have any time to invent any new music style…
…then things changed.
It turned out that the best way to emulate what you already liked to listen to was to actually learn how to play it - not a task completed in 3 months; however, we were playing [bad] gigs at church youth clubs before we could really reliably tune our guitars.
Then came punk - theoretically an excuse to never learn to play or even tune your guitar.
By the time we caught up to that, though… almost miraculously, we'd actually learned how to play [The miracle was actually a whole lot more practise, but we didn't realise that at the time]
Then we got bored…
…We can do that - punk, been there, done that, wore the ripped t-shirt & still have the stains down the front to prove it.
What's next?
Well, you remember Autobahn? Well, turns out this synth thing is a whole new way of proving you can't play very well - but no-one is going to realise it for a long time - by which time we may have learned to play those too. Let's give it a go…
So, late 70's, early 80's there were these things that made not very convincing boink-squeak noises - but, hell, they gave us something to think about.
They also wanted more of our money to be able to join in. One synth wasn't going to get you far, you also needed a multi-track tape machine to work on; let you bounce tracks together & come up with some fuzzy yet inspiring new songs.
So we wrote songs based on 'what new toy we bought this month' - not the 'best' way to write, but a way to push the boundaries of a bedroom studio.
Next we got a 16-track, some outboard effects & if we were lucky, even a real spring reverb.
As the bionks & squeaks started to pall, then there were samplers.
We could now not just try to emulate "real strings" we could have a Tutti we could play in different keys - & boy, did we use that a lot.
One thing we did learn was how to 'play the studio'.
How to.. use a Sequencer; sync it to timecode; bounce tracks on tape; edit tape, ¼" & multitrack; fly in a chorus vocal down an entire track; make a dub/dance/party/disco/mix 12" single with only a razor-blade; run a synth through a Rockman; make a DX7 sound like a banjo [& how a banjo-player would use his instrument to do the same, if only we could afford one]; replace the drum machine snare with one we nicked from "Let's Dance"…
…we were in hog-heaven.
By the 90's, sampling was starting to become more 'clever', more like 'the original'.
Then we got the first DAWs, though we still called them 'sequencers' - but they could do audio too & we could finally lose the old tape machines… though we'd like to still master to DAT… at 48K, if we were lucky… not realising that sample-conversions back to 44.1 were not doing us any favours in the 90's.
By 2000, we had widespread internet, MP3s & DAWs that had lots of plugins; some free, some 'stolen'… until we could afford to buy them…
..but we had access to more noises than ever in the history of man.
So what did we do with them, this plethora of new sounds & techniques available to us?
We used the presets.
If it didn't satisfy in 6 clicks, on to the next plugin.
We wanted to sound like everyone else - & now it was very possible. We had access to all the same noises they did; a studio in a box. Forget mic technique, forget production style, we all now use the same things, we all sound the same.
There are still good & bad, but the access to the 'noises' is now ubiquitous.
So…
…what's next?
At some point, sometime, someone will actually start to investigate how to "play the studio" again - find something other than presets & instant gratification; stop copying what is 'this month's hit' - because, by then, you're 3 months late to be any kind of fashion statement.
Make something new by actually working at something no-one's tried in a long time…
… be original
Learn from all that has gone before… but learn
Apologies - this was a complete 'stream of consciousness' rant. I may hone it later, if it grabs any interest ;-)
Comment: +1 for length - and good point, it must have been so much easier to make your 'own' sound back in the days. I even managed it... *my* sound wasn't very good though...
Answer: Well, I'd class dubstep as an entirely different kind of 'electronic' music. It's still electronic, but so is house music, and that's considered an entirely different thing to trance or techno. There's always something new to explore.
Comment: I agree that it's new and distinctive in many ways (or was when it first appeared - it must be getting on for 15 years old itself now!) though it seems to me to be a kind of aftershock (See what I did there :) of the late 80s - early 90s electronic revolution though, rather than a *major* new tentacle reaching out (how's that for a mixed metaphor)...
Comment: *there's not a lot POST mid-90s* - that's kind of my point really. 20 years is a long time for "not much" to happen!
Comment: @topomorto I think 'major' is perhaps what we're hung up on. Going back to my answer, genre shifts *felt* major pre 2000 mainly because they had a much greater market saturation due to how the music industry marketed them. Post 2000, se simply have fewer major genres but a lot more niche genres due to the major shift in the industry. A parallel might be to look at arena bands. Pre 2000 much of the pop genres had artists at the top that would routinely sell out stadiums. That's not nearly as true anymore. As the industry fragmented, it became more difficult any one genre (and, in turn, any...
Comment: ...one artist) to grab a large marketshare of the audience.
Comment: +1 on the pun, and I'm sure that along the 80's and 90's, people thought we had hit the limits... before several key genres revolutionized the world.
Comment: What key genres are you thinking of that originated post mid-90s?
Comment: Grunge would be my first answer, alternative rock in general also had a massive surge in the 90's. And there's not a lot POST mid-90s, but in general in the 90's, music genres were often being made big.
Comment: append: Forgot to mention Nu-metal.
Comment: Well grunge started mid 80s (Deep Six compilation, etc.) and some would argue *ended* in 1994 with Kurt Cobain's death.
Nu-metal definitely post-dates grunge, but even then arguably started early-mid 90s. And like Dubstep it seems to be somewhat of a logical progression from things that were already popular previously (although again I do agree that it was a new thing)...
Comment: @topomorto define 'lot'. mid-90s on could include all sorts of genres...grunge, ska-punk, nu metal, death metal, britpop, neo-soul, indie, emo, garage rock, power duos, grime, dubstep, eurodance, synthpop, K-pop/J-pop. I don't think 'not much' is valid.
Comment: @DA. A lot of those things started mid 90s or even 80s. I absolutely agree that a lot happened in *that* time... but my question is partly based on the premise that much *major new* stuff has happened since. Are there really any counterexamples in that list?
Comment: @DA ... yes, and you could consider the ability of niche genres to gain visibility and develop a more exciting development than having occasional big "company-ordained" shifts.
Answer: Music is constantly shifting and moving with trends and against trends.  60's and 70's explorative music eventually gave way to Punk, which was the anthesis to Progressive Rock.  Angry youth who couldn't play instruments but desperately wanted to be heard.
Eventually the musicianship of bands like Yes, Genesis and Rush gave way to sterile music like Culture Club and Simple Minds.  Then again we had an upsurge in angry musicians who had a lot to say and wanted to rebel, and 80's Hair Metal was born.
Eventually that died down and was replaced by softer bands like U2, Dave Matthews and others, and then in the middle of the 90's we were hit with Grunge.
Always this ebb and flow, with lots of overlap.  Music will always evolve, and new genres and sub-genres will always be born.  Why?  Mainly because as a people, we love to categorize.  And when something doesn't fit neatly in a box, we will just give it a new name.
Comment: ...I note that you end your story with the mid-90s, which is the 'cut-off point' I mentioned in the first place!
Comment: Well, EDM is the new rage (Skrillex, Bargore, et al), so that's a new genre.
Comment: EDM started in the 80s, or arguably even earlier. Dubstep has steadily got more popular recently but still (as I said on DJ Aftershock's post) seems like more of an evolution of grungy electronic stuff that was around in the early 90s. Still, it does seem like it is evolving - Skrillex (I just had a listen) seems to have a kind of 'mashup' thing going on...
Comment: Having said that, these guys (in 1992) had a kind of mashup thing going on too... https://www.youtube.com/watch?v=BkczzkGrYDQ
Comment: This gives an (oversimplified) version of music history, but it does not address the question, which is about the seeming lack of new genres. That the pendulum isn't swinging as much as it used to...
Answer: I don't believe that something really new will happen in pop music with the limited palette of chord types and chord progressions currently used.
After all, if it's true that there are only 4 chord types commonly used (major, minor, dominant 7th, and suspended 4th), and a I IV V chord progression (or variation thereof) is standard compositional fare, the workable combinations will be explored and exhausted, eventually. I argue that this has happened, but wouldn't be able to say exactly when it did.
Sure, music could continue to evolve rhythmically, only. We could have new rhythms and hybrid-rhythms of all kinds. We could have new dance crazes and amazing vocal gymnastics performed with the spoken word.
But I think that if pop music were to embrace more interesting melodies, extended chords, complex harmonies, subtle chord progressions, and virtuoso solos that are improvised - it would open up whole new vistas.
Of course, if that happened, something like jazz music (think Big Band Swing era) would be pop music, once again :)
Comment: Hasn't "pop" music already explored interesting melodies, extended chords, subtle chord progressions and virtuoso solos in the progressive rock of the '70s?
Comment: You missed my favourite chord, the suspended second, and its cousin the minor 9th - not to mention the majestic open fifth! On the other hand, the dominant 7th seems to be on the slide (as mentioned in the linked article).
Comment: I would agree with you about progressive rock of the '70s having already explored the things I mention - except for "extended" chords and possibly "improvised" solos. So, I would say that jazz fusion (so far) has been the only genre that completely "fills the bill", for me. And I'm not suggesting that some new genre should have "all" these characteristics because we'd have deja vu (jazz fusion - which we still have anyway) all over again. They're just components to consider playing around with.
Comment: A lot of music plays around with all these things, creating new amalgamations of already existing genres. All types of chords have been used, and improvisation is no stranger to household names as Allman Brothers and The Grateful Dead. Something akin to a new genre hasn't occurred for quite a while, which is what the question, in my understanding, is about.
Answer: New genres are typically innovated by an isolated closely-knit subgroup from a specific geographic location -- jazz from New Orleans, house from Detroit, hip-hop from the Bronx, reggae from Jamaica, bluegrass from Appalachia, and so forth. What makes the new genre distinctive is the way it develops for a while, aligned solely to that subculture, and insulated from outside influences.
The main thing that has changed in the modern world is that people are connected in different ways. The internet has given rise to smaller, less localized and less isolated subcultures, so it tends to spin off an endless variety of short-lived subgenres rather than create big, infrequent seismic changes as was true in the past.
Despite that, the next big genre has probably already been born somewhere --some forgotten and isolated refugee camp perhaps --invisible and inaudible to everyone except those who are creating it. We'll learn about it years later, when it finally goes mainstream.


How to change the URL without page reload in Magento

Question: I am developing a site like http://charitybuzz.com using Magento. If you can check they have shown all the products in home page and by clicking on a category the page URL changes but without any reload. I need the same thing done on my site, Can anybody help me out?
Answer: See the answer provided here
The idea is to make ajax calls for certain urls and then use window.onpopstate.
Something like this (copy/paste from the answer mentioned above).
window.onpopstate = function(e){
    if(e.state){
        document.getElementById("content").innerHTML = e.state.html;
        document.title = e.state.pageTitle;
    }
};

You ajax response handling function can look like this (copy/paste again because of the lack of imagination)
function processAjaxData(response, urlPath){
     document.getElementById("content").innerHTML = response.html;
     document.title = response.pageTitle;
     window.history.pushState({"html":response.html,"pageTitle":response.pageTitle},"", urlPath);
 }

you can make changed in onpopstate function in order to achieve the desired sliding or fading effects.
oh yeah...and not all the browsers support this. Only Chrome, Safari, FF4+, and IE10pp4+


Compare files in two folders with different sub-directory names and structure

Question: I randomly copied and also moved some of my images to a different folder for making a video. How do I know which files were moved so as to copy them back to the source. The problem is both the source and destination folder have different sub directory structures within and softwares like scootersoftware, totalcommander couldn't help because of this (or am i using them wrong?). I just want all the names of files and their locations that aren't present in source but present in destination directory.
Answer: Quite old thread but it may still be helpful...
– You could have used hard links instead, to have those files in both locations at the same time without actually copying them. LinkShellExtension makes that pretty easy.
– The files which have been copied will have a different creation date (more recent) ; the files which have been moved will have retained their original creation date. So, searching for files according to their creation date might be a solution in a case like this.
– WinMerge2011 (a fork of the original WinMerge) has the option to compare folders with their subfolders but ignore the subfolders' structure : just click on the box beside "Include subfolders" once to have it "half-checked" and enable that option ; clicking a second time will make it ignore the subfolders entirely. I haven't tested that function yet so I can't comment on its efficiency or relevance in a case like this.
– AllDupe, a duplicate file finder, now includes the option of displaying non-duplicates only, i.e. files which are unique in the folders being analyzed. To make it proceed faster if those folders have many large files and you only want to recreate the original structure of the source folder, it can probably be set to scan both folders by size and/or name and/or modification date, without reading the contents of the files (but it's still recommanded, you never know when corruption can occur).
Answer: 3rd party utilities like WinMerge or DiffMerge can help. For a CLI solution you may use the built-in Robocopy.
For example, the following command-line lists the differences (only sub-directories, not files.) between two parent folders namely folder1 and folder2
robocopy "d:\folder1" "d:\folder2" /E /S /NFL /L

To include files in the comparison report, remove the /NFL flag. Also, check out robocopy help to learn more about the logging options.


Sampling from Posterior without MCMC

Question: I want to sample from the posterior density $f(x \mid y)$ which is related to the prior density $f(x)$ and likelihood density $f(y \mid x)$ via Bayes' rule:
$$
f(x \mid y) = \frac{f(y \mid x) f(x)}{c}
$$
where $c$ is a normalizer.  Let's say both the prior and likelihood are very simple and I can sample from them directly using standard techniques, e.g. Gaussian.  Specifically, say $X \sim \mathcal{N}(\mu, \sigma_1^2)$ and $Y \mid X = x \sim \mathcal{N}(x, \sigma_2^2)$.  I can then sample from $f(x)$ directly, and given this sample can obtain a sample from $f(y \mid x)$ as well.  Is there some method to use these samples to obtain a sample from $f(x \mid y)$?  As I understand, MCMC would be used if the posterior is "difficult" to sample from, but it seems it should be easy in this case.
Comment: I believe Variational Bayes or Laplace sampling could be used here.
Answer: If $X \sim N(\mu, \sigma^2_1)$ and $Y|X = x \sim N(x, \sigma^2_2)$, then the posterior distribution $X|Y$ is also a normal distribution.
$$X|Y=y \sim N \left( \left(\dfrac{\mu}{\sigma^2_1} + \dfrac{y}{\sigma^2_2} \right)\left(\dfrac{1}{\sigma^2_1} + \dfrac{1}{\sigma^2_2}  \right)^{-1}, \left(\dfrac{1}{\sigma^2_1} + \dfrac{1}{\sigma^2_2}  \right)^{-1}  \right) $$
So this is also easy to sample from. Such an instance of the posterior being from the same family of distributions as the prior is called conjugacy. You can see more combinations to priors and likelihoods that lead to feasible posteriors here: https://en.wikipedia.org/wiki/Conjugate_prior
Comment: The fact that sampling from the prior and likelihood is easy does not generally mean that the posterior will be easy to sample from. There is no algorithm that leads to sampling from the posterior using samples obtained from the prior and likelihood. Now, if the posterior is a simple form (like the above example) you can use direct sampling. If the posterior is complicated (intractable), you generally resort to MCMC, after trying Monte Carlo methods (rejection sampling, importance sampling etc).
Comment: Thanks for the info, but I meant for my question to be more general.  That is, given the prior and likelihood are easy to sample from, is there a method to obtain a sample from the posterior besides MCMC?
Comment: This is somewhat connected with my unanswered question on [how to simulate from a geometric mixture](http://stats.stackexchange.com/q/202343/7224)?

Sampling from Posterior without MCMC


Restore Windows 7 Image to a different computer

Question: I have a PC running windows 7.  I have created a system image from this PC and I'd like to 'install' that system image on a different machine.  But I keep getting an error message after running the recovery console that the computer could not boot up do to a general error.  Is it possible to create a system image on one PC and load the image on a totally different PC?
Comment: To my knowledge it is possible, but usually only when the PCs being setup have identical hardware to the original computer; this is because of the nearly infinite possible combination of hardware and devices that can exist just on the motherboard make having the correct drivers installed essential. However, someone with more experience with this may have a more positive answer for you.
Comment: Quote: "PCs being setup have identical hardware to the original computer" - This is how XP and earlier systems worked - Vista and Win7 are more hardware independent.  I don't recall if CPU type makes a difference (Intel vs. AMD) but the virtually all Intel images of an XP or Vista system should be deployable to a another Intel system that meets or exceeds the OS requirements.

How did you create the image?  What software did you use?  What is the EXACT error message?  Why are you going into the Recovery Console?
Comment: @Multiverse is correct. In my experience, Vista and Windows 7 will boot up (at least in safe mode) provided you're running on the same architecture: i.e. Intel or AMD. But you need to give us more information.
Comment: I have, without issue, deployed an image created on a Dell E6510 laptop to a Dell Optiplex 755 desktop... I think most people would agree, these are very different systems.
Answer: I found this very interesting. It doesn't mean it won't work. (Indeed some backup/imaging tools explicitly boats this capability.) But it does mean, as far as I understand, that MS doesn't care about this scenario.
Microsoft Article 279624 -
How to move a Windows installation to different hardware

Over the life cycle of a Microsoft Windows operating system, you may
  have to restore a system state backup that is installed on one
  computer to the same physical computer or even to a different physical
  computer. Recovery from the following events may require a restore
  operation: (...)
You can restore a system state backup from one physical computer to
  the same physical computer or another computer that has the same make,
  model, and configuration (identical hardware).
Microsoft does not support restoring a system state backup from one
  computer to a second computer of a different make, model, or hardware
  configuration. Microsoft will only provide commercially reasonable
  efforts to support this process. Even if the source and destination
  computers seem to be identical makes and models, there may be driver,
  hardware, or firmware differences between the source and destination
  computers.
Answer: As an alternative you could create the image with Symantec Backup Exec System Recovery and restore it to the different hardware.  Use this often and itw works very well.  Just did a laptop  restore from a current Dell E6500  to a Dell D810 wee had spare.  Worked perfectly even though harware was very different.  A few drivers needed installing but only minor issues.  There is a wizard that will check for drivers which can then be added to teh recovery disk.
Comment: I think Paragon has similar software...http://www.paragon-software.com/home/brs/cat_migration.html
Answer: Use ImageX (Microsoft's free imaging tool.) to capture the image, load that image into a VM (like virtualbox) and then sysprep it using the /generalize flag.
<code>sysprep /generalize /shutdown
</code>
Generalize prepares windows to be loaded to another PC. If you specify this option, all unique system information is removed from the Windows installation. The system's SID is reset, any System Restore points are cleared, and event logs are deleted. The next time the computer starts, the specialize configuration pass runs. A new SID is created, and all drivers are cleared out.
It won't be easy, but using imagex, a VM and sysprep. It can be done.
Answer: One common cause would be trying to deploy an image that's running in AHCI or RAID mode on a machine with the controller set to IDE legacy emulation mode.  You should check this setting in your BIOS.
As Multiverse IT says in the comments, Vista/7 are largely hardware independent beyond this.  We'd need more specifics on the machines to try to pin down a problem.


Internetworking packet transfer

Question: What happens when a packet gets lost or corrupted? Mostly flow control is in the data link layer with acknowledgements. Does this happen on network layer as well like among multiple networks. A packet is encapsulated in a frame so do two machines on two networks send acknowledgments for a each received frame(containing a packet)?
Comment: IP (both IPv4 and IPv6) is a connectionless protocol, and it has no mechanism for acknowledgement. Packets that are lost or dropped are simply lost. Modern data-link protocols do not have acknowledgements or flow control. You are really asking about transport protocols, and some have that, but many do not, and it would be up to the application to handle that on those that do not.
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
Answer: On the network layer and the data link layer, packets/frames are generally not acknowledged (with few exceptions). The protocols use robust designs but lost packets stay lost. If required, recovery needs to take place on higher layers.
Some transport layer protocols acknowledge data (most prominently TCP) while others do not, for instance UDP.
Note that TCP doesn't need to acknowledge every single segment but it can acknowledge "in bulk", up to a certain point. Also note that TCP doesn't wait for each segment to get acknowledged before it sends the next one. Instead, it uses a transmission window where acknowledged data slides out, allowing fresh data to slide in.
The intention behind this is to keep intermediate network devices very simple (the ability to wait for acknowledgements and resend lost data requires data buffering) and let the end nodes take care of reliability.
Answer: It depends on the data link protocol. Some obsolete ones, like X.25, do acknowledge frames. 802.11 (WiFi) also does.  But Ethernet does not. If a corrupt frame is detected, it is silently dropped.
Comment: Actually WiFi does acks: http://www.cs.miami.edu/home/burt/learning/Csc524.052/notes/wifi.html

Internetworking packet transfer


Wireshark - How do i filter the TCP[RST] packet?

Question: I am looking for filter out the TCP[RST] packets on wireshark.
I have tried tcp.analysis.flag but it didn't help.
Answer: tcp.flags.reset==1 [displays all TCP resets]
for more flags
Answer: Also if you ever want to filter a certain filter like this go to the middle pane and then go to the actual line it says what you want to filter. (In this example the reset flag) Click that it will highlight it. Something to note once it is highlighted it will show you the filter to search for in the lower left hand corner.(tcp.flags.reset) If you right click the highlighted section now you can click on filter and you have some options there. You can search selected (== or eq) not selected (!) and selected (&&) or selected (||) and of course the not versions to the and and or. Once you click on your choice it will be placed in the filter bar the way you chose. I hope this helps its a really nice feature.
Comment: As it's currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer).


What's the boundary of microscopic world and macroscopic world?

Question: In other words, what's the maximum size of a Quantum denizen upto which it shows Quantum behaviors? How big do I need to create a molecule (or, collection of molecules) so that Feynman's multiple path and multiple history would no longer be applicable to it? In a sense, Feynman's multiple path and multiple history should be applicable to macroscopic system producing Quantum Decoherence, but I am talking about a molecule which could show interference with Multi-slit Diffraction Experiments.
Comment: The boundary between the quantum and the macroscopic world doesn't necessarily stay in the dimension of the objects. Of course, until now one didn't obtain interference with pieces of chalk or pebbles. But interference fringes yes were obtained with molecules of tetra-phenyl-porphyrin, which is a **biomolecule**, and fluorofullerenes. The experiments were done not with the 2slits, but with gratings (repeated slits). The main idea was, as these molecules are quite massive, to obtain for them very, very small velocities, so as to get a sufficiently big wave-length.
Comment: The boundary between the microscopic world and the macroscopic world is the mesoscopic world of course!
Comment: Maybe interesting: http://www.df.uba.ar/users/giribet/f4/interference.pdf.
Comment: @sofia That looks like an answer, not a comment.
Comment: @sammygerbil So what? Anyway, my answer below is more detailed.
Comment: @Sofia Oh I am sorry, I did not notice that you had also posted an answer.
Answer: It is very difficult to say where is the boundary in dimension of objects, between the classical and quantum behavior. The surprising fact is that we are not even sure if the boundary stands in the dimensions of the objects. And it is not exactly true that "you can apply Quantum Mechanics to macroscopic systems, but the effects are negligible and thus experimentally undetectable with current technology".
The main problem in obtaining interference with big objects is that their wavelengths are terribly small. If the object is by orders of magnitude bigger than its wavelength we won't see interference.
Until now one didn't obtain interference fringes with objects as big as pieces of chalk or pebbles, but yes we obtained with very big and complicated molecules as tetra-phenyl-porphyrin, which is a biomolecule, and fluorofullerenes. In these experiments the major idea was to get for the molecules, very, very small velocities, s.t. the wavelength be sufficiently big.
The experiments were done not with two slits, but with gratings (repeated slits).
Let me add an important fact. The internal state of these molecules is very complicated, s.t. the surprising feature was that it couldn't be guaranteed that molecule after molecule had exactly the same internal states. Despite that, interference was obtained. The figures below will give you some idea on the complication of these molecules.
IMPORTANT NOTE: The issue of the limit between the quantum world and the macroscopic world, is under current intense investigation, see in the arXiv quant-ph the articles and experiment reports of Prof. Marcus Arndt.
Comment: `The main problem in obtaining interference with big objects is that their wavelengths are terribly small. If the object is by orders of magnitude bigger than its wavelength we won't see interference.` ~> Maybe, you should elaborate on this. If it's correct, isn't it possible to deduce that size theoretically?
Comment: @SachinShekhar , Too soon to decide on size. This domain is in research. As I said, the fact that interference was obtained **even if** the strict identity of the internal structure of the molecules is **not guaranteed**, is a very surprising fact, very encouraging. There are 3 major factors in these experiments: obtain *coherent beams* of molecules (or objects that we study), reduce their *transversal linear momentum* s.t. the wavelength exceed their linear dimension, and build *suitable gratings*, i.e. with sufficiently small grating constant, and resistant to bombardment by the molecules.
Answer: Theoretically speaking, you can apply Quantum Mechanics to macroscopic systems, but the effects are negligible and thus experimentally undetectable with current technology. General Relativity also applies to small systems, but the results are so close to Newtonian gravitational theory that the discrepancies are experimentally undetectable with current technology. An overlapping zone where both Quantum Mechanics and General Theory of Relativity can be applied because they are significant is in a black hole and during the beginning of the big bang, because the gravitational effects are huge and because the space is small quantum effects become significant.
Comment: You misinterpreted the question. See the update.


Unable to install HAXM in Windows 10

Question: I'm working on android studio when I run the application it shows an error when I tried to install emulator through sdk it shows
ERROR: x86 emulation currently requires hardware acceleration!
Please ensure Intel HAXM is properly installed and usable.
CPU acceleration status: HAX kernel module is not installed!
I'm using Windows 10 and it does not have hyper - v so I'm unable to install HAXM .please tell me the solution?
Answer: I have ran into this issue before on OSX.
How I fixed it:  Delete/Reinstall the Android SDK.  Sometimes if you install the SDK in a different location then it was before, may help as well.
Also you could check and see if you need to install any new updates in the SDK it's self.

Unable to install HAXM in Windows 10


In the case of the time-independent Schrödinger equation, what is the uncertainty on the measurement of the energy of the particle?

Question: Because there only exist stationary state solutions of the time-independent Schrödinger equation, which correspond to states with single, definite energies, and the energy expectation value is equal to the energy of a given state, does that mean that there is no associated uncertainty with the measurement of the particle?
Answer: If the system is in an eigenstate of the Hamiltonian, such that it solves the time-independent Schrödinger equation, then yes, the energy uncertainty of that state is zero.
It's important to note, though, that for that to hold the system needs to be in that eigenstate for all time, i.e. the $\Delta t$ in the Heisenberg uncertainty principle needs to be infinite. If the system changes at some point (i.e. for some mundane task such as initializing the experiment or performing a measurement to terminate it) then you can no longer state that the system is in that eigenstate solution of the TDSE.