Comparability of Landsats

Question: I have collected data (spectral bands) from Landsat 4-5 and Landsat 8. I was calculating NDVI when I noticed that the two Landsats have different band numbers designated as Red and Near Infra Red (needed for NDVI calculation). When I checked the wavelengths associated with these bands here Landsat Band Description I noticed that the wavelengths also differ a bit. For example I used bands 3 and 4 (Red & Near Infra Red) from Landsat 4-5 and bands 4 and 5 (Red and Near Infra Red) from Landsat 8 for NDVI calculation, but the wavelength range of band 3 in Landsat 4-5 is not exactly the same as of band 4 in Landsat 8. Is there any way to convert things so that they are same and comparable. I got big variances between NDVI values from the two satellites that's why the confusion.
Answer:
where ̅, RMSD, and ̅ are the mean difference, the root mean square deviation, and the mean relative difference respectively between corresponding Landsat-8 OLI (viOLI) and Landsat-4/5 ETM + (viETM +) values (TOA or surface spectral reflectance or NDVI) for n pixel values
Assume that TM bands respond linearly within 0-255 for spectral reflectances of 0-100%, then the change rate is 0.39% reflectance unit per DN unit.
For e.g., DN = 100, the actual DN values can be 99.5-100.5 as a result of truncation. That is, the reflectance error due to 8-bit quantization is half 0.39% (~0.20%). When correcting for solar effects, the reflectance should be divided by cos(SZA). At a large solar zenith angle (SZA), the reflectance error can be amplified. For SZA=60°, the error is 0.39%. This value is larger than that of OLI, but is still acceptable compared to other uncertainties, such as the 5% sensor calibration uncertainty.
SOURCES:https://www.sciencedirect.com/science/article/pii/S0034425715302455
          and researchgate.
Answer: The results using bands 3/4 and 4/5 should be similar and comparable, but they cannot be converted to identical ones due to the difference in wavelengths.
The difference in NDVI results between the two sensors is expected and normal, since you are comparing values from different dates (it is impossible to have similar dates from TM and 8 since Landsat 5TM was decommissioned before the release of Landsat 8): the results vary lesser due to sensor differences and more due to changes in vegetation health & cover and atmospheric effects. NDVI results can be different even between a short time, or even from the same sensor and date if you use correction on your data (TOA, surface reflectance etx).
The variety of NDVI across time(and not it's absolute values) is of interest in the use of NDVI (and other related vegetation indices) since it enables us in the interpretation of vegetation health, status and cover.
Comment: This paper suggests that there will be significant differences owing to the different sensors:
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4241441&tag=1
Yes the difference due to varying dates is expected but when you compare at the same time of the year between different years then they have to be somewhat similar. I have a pattern of NDVI values varying between 2000 and 2015 which remains consistent until the values from the new satellite come in from 2013. Then the pattern suddenly changes which means the sensors do cause some important differences.

Comparability of Landsats


What's the difference between Open Data and Big Data

Question: Open Data can be Big  Data, and Big Data can be Open Data -- but they are not synonymous.  What is the major difference between the two?
Comment: Nick, These terms are unrelated. Please refer to the definition of these concepts ([Open Data](http://en.wikipedia.org/wiki/Open_data), [Big Data](http://en.wikipedia.org/wiki/Big_data)). If you don't understand something specific about the definition in relation to Open Data SE, please feel free try again by describing what you are having trouble understanding specifically. Thanks.
Comment: Robert, thanks!  The terms mean different things, but are both terms to describe data (and even movements).  I asked this question because I've seen these terms used occasionally interchangeably in non-expert settings, and I thought it would be helpful to have an answer here that explains the venn diagram of the two terms.  If that's not helpful or is inappropriate for the Open Data SE, then please close.
Answer: They are not the same at all. Datasets are Open if they are available under a free license to everyone. Datasets are Big if... well, they are. Typically big beyond where common software can handle them in real time.
For example Facebook and Google work with Big Data that is not Open.
Most Open Data sets are actually an example of Small Data: The datasets themselves are not huge, but there is a large number of them that can be correlated to increase their value.
Answer: They aren't synonymous, but big data can be inherited by open data. "Big" is just a quantifiable attribute given to data; meaning there is a large amount of it. "Big" data can also be misrepresented in terms of scale. Your big data could be small to someone else and vice versa. "Open" data is an idea that data should be readily available to the public.
Answer: Big Data.
I think the point has been missed about "Big Data". It doesn't need to be large in volume.
There are historically (from 2001) three tenets of big data

high volume (e.g. Facebook, Google index)
high velocity (e.g. mouse click data being analysed every second for user behaviour triggers)
high variety (e.g. data that has a diversity of data types stored within it, e.g. documents, images, structured information, relationship information, etc.)

If data has one or more of these, then it is considered "big".
Open Data.
This very good article on open data that shows what it is.
For Example.
An open data set could be small, slowly changing or non-changing, and contain a well structured simple format - this would not be a "big data" set. If we consider data.gov.uk's 'Trees in Camden' data set, it is a 2.8 Mb csv file of council owned trees which is updated periodically (maybe monthly).
Answer: Open Data vs Big Data.
Open Data: Open data is data that anyone can share and publicly accessible. Open data is a description or type of data, usually with little to no restrictions.
Big Data: Big data exists on a large scale that usually cannot be processed by regular software. It's massive in size and includes a set of datasets.
Open Data does not need to be related to Big Data in order to exist. These are basically separate terms used to describe data. Hope this helps!


How was Saul changed to Paul?

Question:
Acts 13:9 (NIV) Then Saul, who was also called Paul, .....

This verse does not explain much how Saul became Paul. Who changed his name? Why was it changed?
Answer: Actually, we don't know that his name was changed at all. He may have had both names to start with as per the custom of his day as both a Jew by blood and a Roman citizen. After his conversion and change of direction he seems to have decided his other name was a better moniker.

Many mistakenly assume the Lord changed Saul's name to Paul sometime after Saul converted from Judaism to Christianity, which happened during his encounter with Christ on the Road to Damascus (Acts 9:1-19). Unlike the instance of Jesus changing Simon's name to Kepha (Gk. Petros) as a way of signifying the special role he would play in the Church (Mt 16:18, Jn 1:41-42), in Paul's case there was no name change.
Saul of Tarsus was born a Jew, "circumcised on the eight day, of the race of Israel, or the tribe of Benjamin, a Hebrew of Hebrew parentage, in observance of the law a Pharisee" (Phil 3:5). The Hebrew name given him by his parents was Saul, but, because his father was a Roman citizen (and therefore Saul inherited Roman citizenship), Saul also had the Latin name Paul (Acts 16:37, 22:25-28), the custom of dual names being common in those days. Since he grew up in a strict Pharisee environment, the name Saul was by far the more appropriate name to go by. But after his conversion Saul determined to bring the gospel to the Gentiles, so he dusted off his Roman name and became known as Paul, a name Gentiles were accustomed to.

(source: catholic.com)
The suggestion that the confusion is born out of having had multiple names from birth is born out by other sources such as Protestant writer F.F. Bruce, although his conclusion is that both names would have continued in use and it is only the preference of the NT writers in which we see a change.

He was born into an orthodox Jewish family, and as his father was a Roman citizen, he inherited this distinction, a rare one among eastern Jews. In Jewish circles he bore the name of Saul, but in the Gentile world he was commonly known by his Roman cognomen Paullus, Anglicized as Paul [...]
Saul's father was a Roman citizen… [so] Saul was born a Roman citizen… As a Roman citizen, he had a Roman name, consisting of three parts: praenomen, nomen gentile and cognomen.2 What his praenomen (first or personal name) and nomen gentile (family name) were we can only guess; his cognomen, however, was Paullus, by which (in its English form Paul) we usually call him.
In family circles, however, he was known by his Jewish name Saul.
2. The threefold Roman name may be illustrated from the full names of such famous Romans as Gaius Julius caesar, Marcus Tullius Cicero, Lucius Cornelius Scipio.

(source: F. F. Bruce, The Spreading Flame)
In any event, we do not have a Scriptural source for the why and how of the name change. The most direct hint we have is the one you mention in Acts that simply notes he was "also known as". This is combined with the references to him by both names and and our own deductions from the correlation in how he was generally referred to before and after his life changing encounter with the Christ he had been persecuting.
Answer: How was Saul changed to Paul?
It's possible that Paul changed his own name, especially to divorce himself from his former Jewish activities, where he arrested and murdered many of Jesus' own. He may have changed his name to be better received by the church, because he was notorious throughout the whole church by the name of Saul. Church people feared him and it was recorded that many still did not trust his conversion as genuine, even years after they heard about it, so therefore refused to trust him.
Saul as a name means 'asked or prayed for', and Paul means little or small. Paul would certainly agree with becoming less or smaller so Christ could become greater. It is a meek humble name, in its' meaning, which are traits God likes.
Comment: @Mawaia, God may have changed his name, like he changed Peter's name for the very same purpose.
Answer: Paul, himself, never uses the name Saul, which occurs in reference to him only in Acts of the Apostles. Acts first refers to 'Saul' as Paul in verse 13:9, which follows immediately after mention of Sergius Paulus, described as the deputy (proconsul) of the country. It is possible that Saul was already known as Paul, and the author of Acts chose this encounter as an opportune point at which to introduce the name Paul.  Another possibility suggested by the conjunction of Acts 13:7 and 13:9 is that Saul chose to adopt the name Paul in honour of the proconsul:

Acts 13:7,9: 7 Which was with the deputy of the country, Sergius Paulus, a prudent man; who called for Barnabas and Saul, and desired to hear the word of God . . . 9 Then Saul, (who also is called Paul,) filled with the Holy Ghost, set his eyes on him,

Rex Wyler refers in The Jesus Sayings, page 43, to Josephus' mention of a Saul who violently persecutes Jewish peasants, hobnobs with powerful men in Judea, appears related to Herodian rulers, and participates in scenes parallelled in Acts.  Wyler reports that the parallels suggest to some scholars that this could either be the Paul of Acts, or perhaps the model from which later writers devised certain scenes. The Saul (or Saulus) that Josephus describes was active in the mid to late 60s, which is actually too late to have been Paul himself, but possible as a model for the portrayal of Saul in Acts of the Apostles. A careful reader of Acts can see Saul portrayed as totally disreputable, in contrast to the saintly Paul who replaces him in the narrative. On this analysis, it is possible that Paul never used the name Saul, but that the author of Acts of the Apostles used this name in order to provide a graphic contrast between the early 'Saul' and the later 'Paul', knowing that the name Saul could be associated by many of his contemporaries with another infamous Saul described by Josephus.

How was Saul changed to Paul?


How does Gilgamesh have a futuristic fighter plane?

Question: In the dogfight between Gilgamesh and Berserker, Gilgamesh rides a golden fighter plane that is capable of hovering and flying at great speeds, supposedly by harnessing some "strange green power" (see the opening wings and glow when Gilgamesh prepares to dodge Berkserker's approach). The Gate of Babylon is supposed to contain Gilgamesh's treasures of his time, so how did such a futuristic contraption come into his possession?
Answer: This "airplane" is the Vimana. It is recorded in several epic Hindu texts, including the Ramayana and the Mahabharata. In fact, in the original Sanskrit works, there is more than one vimana, but in any case it is a flying contraption that gods would ride. There is no record of them in Babylonian literature as far as I know, but of course Gilgamesh owns the prototypes for all of the technology that appeared in later cultures, which presumably includes this.
Comment: [Here's](http://typemoon.wikia.com/wiki/Vimana) the more relevant Typemoon wiki entry.
Answer: There are several examples of what would seem like futuristic technology in ancient cultures like the Egyptians and Babylonians. In temple of Seti I there are hyroglyphics that depict blimps and helicopters.

Image Source - Wikipedia
The Vimana is another example of this. Also Ea is a construct "not of this world" and is an Anti - World Noble Phantasm that defies the analysis of Unlimited Bladeworks despite not being a Divine Holy Relic like Excalibur. This suggest that Vimana and Ea are of Alien Origin.
This may come into play later as Fate is part of the Nasu-verse and we know they use the many worlds interpretation of time and space, adding or hinting at alien worlds to this is not a stretch for them.
Answer: Basically, because Gilgamesh was the very first king, every treasure was claimed by him, including everything made by Man. Even after he died, things than Mankind dreamed up afterwards were claimed by him. That or the power of magic back then meant that his kingdom was able to make magical things equal or greater to modern inventions. It is also is that as the very first Hero, he must have the prototype to every weapon or item used by later heroes. The only things Gate of Babylon doesn't contain is anything made with new concepts by a new human race, or items made by extraterrestials or with extraterrestial knowledge. In Fate/Extra, he even has a spaceship able to move at the speed of light.
The article I got this all from is worded a little confusingly, but I think it is that if Mankind has or will make something, then as the first King and Hero, he already has it in his vault. So either the Vimana is a magical airship, or it's based on a ship Mankind will make.
Comment: So basically you've rephrased Logan M's answer from 4 years ago.


How to tune the flute by ear

Question: Please, I would like to ask you for an advice: I have big trouble to tune my flute by ear -e.g with the piano before playing the piece,my teacher always tells me whether am I flat or sharp.
And I just dont understand why. I feel like I am not able to match the sound of piano with the sound of my flute in my head. I would love to do it by myself. I am definitely not tone- deaf - I am singing in tune without any problems, as a child I was singing in a choir for 12 years. The flute I have been playing for more ten years and when I am playing I am able to play in tune without problems, I feel it somehow, but I cannot say whether am I flat or sharp. What is wrong? I desperately love playing flute and I have just decided to fulfill my dream and I am going to study it further but I have to be able to tune....
Answer: Not an uncommon problem.  It can be hard to seperate pitch from timbre when comparing notes on different instruments. I know one successful professional performer who habitually tuned his instrument sharp.  It (sort of) worked in live performance but he knew something was wrong in recordings.  It just needed pointing out that he was confusing 'bright' with 'sharp'.
Get yourself an electronic tuner.  There's probably a free 'app' for whatever computer device you're reading this on.  Set it to A - or whatever note you want to tune to - and check that the piano A is showing the right pitch.  A little practice in matching what the tuner tells you against what you hear from the piano, and your problems will be over.   Or just use the tuner all the time!
Another idea:  don't tune to a single note, play a scale with the piano.
Comment: When I played clarinet and bass clarinet in concert band, we'd always tune against the conductor's electronic tuner. Even with my absolute pitch, it's hard for me to detect a 10-cent deviation from A440 tuning without previous references, and 10 cents was considered unacceptably sharp/flat in the concert bands I was in.
Comment: This would have been my answer. Maybe it'll show the piano isn't at concert pitch, too !
Answer: I find it easier to hear one note at a time, (the standard, then the instrument I am tuning) so I can hear the differences in pitch more clearly. I find it particularly difficult to tune to the piano because it is not just one note! Other strings vibrate sympathetically and many, many overtones are produced. Find the exact pitch with that! It is actually impossible. https://contentspiano.blogspot.com/2006/02/sympathetic-vibrations.html
Given that the strings on the piano may not be exactly in tune with each other, and given that most pianos in educational and other public facilities are not often in tune or even properly cared for, and given that I can tell when my piano goes out of tune simply by the fact that a note lost some of its resonance, the piano is really not a great standard by which to tune other instruments. Unfortunately, it is a must if we are going to play with the piano for accompaniment purposes.
If you must play with the piano, try tuning to octaves. Find the "average" pitch you hear and tune to that. My guess is that your teacher is hearing one end of the "out of tune" note and you are hearing the other end (see the article above.) If you tune to octaves, it will all blend more and you and your teacher may find it easier to come to consensus about what is "in tune with the piano."
If you do not have to tune to the piano, use an electronic tuner. Of course, that means only that that ONE note is in tune with the tuner.
Comment: "Of course, that means only that that ONE note is in tune with the tuner." This. From my experience with flautists, tuning A440 to an electronic tuner scarcely helps to bring any other note in tune. It appears like the lip-intonation of individual notes is easily as important as the basic offset tuning, and when tuned by ear, the players seem to get this right more reliably.
Comment: @leftaroundabout, that is true about most wind instruments. Embouchure and air support both contribute to the intonation (or lack thereof).  No instrument is perfectly in tune, even when all the right keys and buttons are pressed, so players learn how to compensate for variances in their instruments, as well as how to use proper technique that assists in playing in tune.
Comment: Perhaps people who take devoted wind instrument lessons have the luxury of tuning multiple notes against an external source. In concert band (my sole source of clarinet and bass clarinet lessons), I only ever tuned against one note--the electronic tuner's Bb. Granted, so did everyone else in the band.
Comment: @Dekkadeci, wind players can learn to play in tune by practicing at home with a tuner that will recognize each pitch and indicate whether the notes is too sharp or flat. Many electronic tuners do this. Then, through practicing scales, long tones, and other exercises while observing the tuner, they can adjust accordingly, using alternate fingerings if applicable or fixing the embouchure, etc. They can also use the tuner to "spot check" notes in a piece they are learning.
Answer: As a beginner step, if you know that you're out of tune, adjust in one direction; if it gets worse, go the other way!
Like most things, developing intuition comes with time.
Answer: Play at the same time as the piano and listen for the beats. When you don't hear them anymore, you're done.

How to tune the flute by ear


Is symmetric encryption vulnerable to plain-text-attacks?

Question: Imagine that Bob sends a message to Alice for symmetric encryption to send to Charlie. (Only Alice and Charlie know the key.) Alice sends the encrypted message back to Bob to send to Charlie. Can Bob compare the plain text he sent to Alice with the encrypted version to guess, for example, what is Alice's AES key?
Answer: If the encryption is any good, no.  What you're describing is a known-plaintext (or possibly chosen-plaintext) key recovery attack, and any encryption system that was even suspected of being vulnerable to such attacks would be considered hopelessly broken by modern standards.
The "gold standard" that modern encryption methods aim for is generally taken to be "IND-CCA2" security, or ciphertext indistinguishability under an adaptive chosen-ciphertext attack.  Loosely speaking, this security property means that an attacker who gets to choose two plaintexts (of equal length) to be encrypted and sent back to them, and may also request the encryption or decryption of any number of other messages, will not be able to tell which ciphertext corresponds to which plaintext.
Comment: @gereeter: Indeed, AES, or any other secure block cipher, is IND-CPA secure in all the classic non-deterministic modes of operation (CBC, CFB, OFB and CTR), provided that an appropriate IV or nonce is used. However, it's worth noting that no non-authenticating cipher mode can achieve full IND-CCA2 security, since all such modes are at least somewhat malleable. For IND-CCA2, you need to encrypt-then-MAC or use an authenticating encryption mode.
Comment: I believe that AES-CTR, at least, has IND-CPA security. This means that the answer to the OP's specific question is no.
Comment: @IlmariKaronen, aren't you rather reducing the attack model to CPA when you are using a MAC (rather than providing IND-CCA/IND-CCA2)?
Comment: @David天宇Wong: That's basically what adding a message authentication layer does: it makes the probability of a successful decryption oracle query (on a message not previously obtained from the encryption oracle) negligible, and thus effectively makes the CCA game identical to the CPA game.
Answer: No, it's not possible. AES has two main properties which makes UNFEASIBLE this attack:

Confussion: 'hiding' the letters, eg: first historical symmetric encryptions such as Caesar or Affine ciphers were only based upon this property (ie, a letter is mapped to another one always). Hence, making this encryption suitable for plain-text-attacks. Even using a naive technique in cryptoanalysis called frequency analysis these ciphers could be broken within seconds.
Diffusion: is an encryption operation where the influence of one plaintext symbol is spread over many ciphertext symbols with the goal of hiding statistical properties of the plaintext (avoiding frequency analisys attack)

Since AES applies both properties in every round (at least 10, depending on key size) it makes nowadays, at least, unfeasible this attack. With respect figuring out the key, it's, once again, unfeasible. Image that, you've decrypted the message, in order to figure out the key you'd need to brute-force the key to seek for a matching.
For further info please visit my github on which I have implemented both ciphers and their pertinent brute-force methods.


Is there any buddhist explanation for deja vu?

Question: I'm not sure we will find that in the pali canon (per haps in Abidhamma?), but is there any thera/senior bikkhu that wrote about it? Is it related to past lifes or any special power of the mind?
Comment: Can you give more explanation on that this is?
Comment: @SumindaSirinathS.Dharmasena It's a feeling that you recognize this scene or situation although rationally you know you haven't seen this (here and now) before. https://en.wikipedia.org/wiki/D%C3%A9j%C3%A0_vu
Answer: The psychology of C. G. Jung who wrote a preface to Bardo Thodol (The Tibetan Buddhist Book of the Dead) may explain the deja vu experience as restimulation of experiences of the collective unconscious in the bardo interval between death and the next rebirth, that he called "archetypes" or universal prototypes for ideas. However before drawing such a conclusion, know that the Sabbasava Sutta (Majjhima Nikaya 2) warns against questions which are seen as "unwise reflection" and lead to attachment to views relating to a self. They include: Did I exist in the past? Did I not exist in the past? What was I in the past? How was I in the past?
Answer: If you have psychic abilities then you might have foreseen or sensed the event before happening.
Also remember we are a bundle of feeling (one of the 5 aggregates) too. Hence we tend to react to these feelings in different ways. Sometimes this notion of deja vu can just be a conditioned response of your mind, than it having any significance. Certain type of feeling trigger certain memories and which in tern trigger more feelings. Your perception forming part of you mind may identify some similarities and cooks up a concept. (This cooking up is what is called delusion.)
Answer: In my experience, it seems to be caused by a precognitive experience--one has a precognitive experience at a previous time and when the event actually comes to pass in the present, the meeting of the two is experienced as deja vu. Many times, I think that people have precognitions in dreams and forget them at the conscious level; in this case deja vu is experienced but without an understanding of its cause.
The idea that the future can be seen is present in the Buddhist tradition. As Suminda mentioned, there is probably a psychic power that allows one to see the future. There is also discussion of seeing the future (incuding future births) through a vipassana power (which is distinct from psychic power) in Pa Auk Sayadaw's Knowing and Seeing (188-196).
Answer: The funny part about Buddhism is that teachers in it don't exist. So as soon as I answer this question, I take in the role of the teacher and I guess thus makes anybody my student. However, because I do not know and the great masters have nothing to teach, I suppose cuddly is right. I don't think Buddhist masters would stress much about this question. Instead they would point you out to where the answer isn't, and that's HERE. The Guru is trying to get you to come off it, and if he sees that you don't come off it, he puts you through a series of tests to simply get you to suffer, and frustrate you. This way you simply get yourself right off it and realize that you had it all along from the beginning. So deja vu is a simple experience, just like nothing else.


How to redirect external web request to localhost's testing server

Question: Some web services calls my web application(www.myapplication.com/external_update_handler).
I need to test those requests locally, so I'd like to know your opinions about how can I "redirect" those requests to my localhost dev machine(that is outside of my web aplication domain) so I can debug.
Probably it's needed a service/server to get those external requests and a desktop application that sends it to localhost:5555/external_update_handler, but I have no idea where to start and simpler options.
Comment: You didn't tell us what server do you use / in general you need to setup reverse proxy. In case your dev machine is accessible from the server, the setup it simple... can be more specific on apache setup
Answer: Either update your code to hit the local version of www.myapplication.com/external_update_handler on the URL/Host it is accessible on, or you can configure the machine running the web service (the ones making the outbound calls to your web application) and configure a hosts file http://en.wikipedia.org/wiki/Hosts_(file) to force the machine looking up your web app to resolve the domain to a different IP, likely the one that resolves to your local environment,.


Is there piano notation for finger sustained notes (as opposed to pedal sustain)?

Question: In piano music how does one indicate that sequential notes in the bass clef are to be sustained with the fingers, not using the sustain pedal?  For example, suppose I have the three sequential quarter notes C, E, G defining a C chord in 3/4 time in the bass and I want each note to be held to the end of the measure after it is struck, but I don't want to use the sustain pedal because I don't want the other notes in the treble clef to "blend" together.  Is there a special kind of slur or other notation to indicate this?  I know that one way to do this would be to break the three notes into three parts (i.e. use a dotted half note for the low C and then above this a quarter rest and half note of E, and above this a half rest and quarter note of G) but this seems like a far too complicated way of indicating what is a common style of playing a sustained "broken" chord note sequence. I also don't want to use arpeggio notation (wavy line) because I have a melodic line in the treble that interfaces precisely with the base notes. Can anyone help?
Comment: Does this answer your question? [What's the proper piano notation for adding one note at a time to a chord and holding all the notes?](https://music.stackexchange.com/questions/115474/whats-the-proper-piano-notation-for-adding-one-note-at-a-time-to-a-chord-and-ho)
Comment: This sort of thing happens in guitar music, too. It's written as separate notes, but sounds so much better when notes are held - they constitute a chord in these cases- so they bleed into each other.It's rarely written 'properly'.
Answer: My answer is ultimately similar to Bob Broadley's, but has one difference that can make for much more readable scores in slightly more complex situations. This is the standard notation for broken held chords like the one you describe, as recommended by Kurt Stone and Gardner Read:

The difference here is that you don't rewrite any of the held notes until the chord is complete. For your specific relatively simple case, I don't think it's much better than Bob's. However, in an even slightly more complex situation:

the readability can be greatly enhanced. One of the things I like most about this notation is that it's fairly clear, even when the pianist hasn't seen it before. I use this notation in a lot of my piano music, and most pianists don't even bat an eye because they've seen it before. The few that haven't still immediately guess the meaning. The notation you describe in your question will eventually be figured out, but looks so much more complicated than the actual method of performance that it can be annoying. Same thing, albeit to a lesser extent, if you rewrite each tied note with each new note entrance. In more complex situations it can become difficult on first glance to ascertain which notes are new and which are being held-over.
Answer: Sometimes it will be obvious to a performer that you need to sustain notes that together outline one particular harmony (a single triad, for instance). If you want to make this explicit, though, you could use notation such as the following:

I'm not sure that this is used that much in piano music, probably because the pedal will produce the required effect (although I understand why you don't want to ask for pedal use here). However, it is a common way to show exact note durations in arpeggiated guitar music.
Also, if you want to make it clear that no pedal should be used, you could write senza ped., in addition to the notation above.
Answer: The main way I've seen this done is to use multiple voices to show the durations. Here is a short excerpt from a piece I was copying into my notation program:
Comment: @LaurencePayne A pianist with small hands will use sustain pedal anyway, disregarding the senza Ped. markings, since their hands can't hold a ninth.
Comment: A pianist seeing that notation, particularly one with smaller hands, may well see the pedal as an acceptable solution.  Senza Ped. will make it clear.
When there is a melody above that would be blurred by pedaling, a good pianist SHOULD choose a technique that combines sustain with clarity.  But remember that higher notes have less sustain anyway, even with pedal.  The performer may not need meticulous instructions quite as much as you think.  Pianos are more subtle than sequencers and samples!
Answer: this would work for some things.  I also like Trikly's idea.
Answer: You can use a Tie to sustain notes in this manner.
There is more here: https://en.wikipedia.org/wiki/Tie_(music)
Answer: It is probably best that you write what you want above the first measure then write (sim.) if it continues in the other measures as shown below.

If there isn't a simple way to notate something you can use a few words to describe it.
Comment: Neither the note-heads nor your words indicate correctly how long the Cs and Es are to be held.


What things to look for when buying my first ukulele?

Question: I want to buy an ukulele, and I have no idea of what to expect or what to look for. Which brands have a good quality-price ratio? What types of ukuleles are there? What do I want to avoid? What to look for?
Answer: There are four main sizes of ukulele: Soprano, Concert, Tenor, and Baritone.  Soprano, Concert, and Tenor are all tuned the same so it's just a question of fretboard size and resonance.  The Baritone is tuned differently and probably not what you want.  You should choose among the other 3 based on what size is comfortable--go to a store and try them out.  Many men find the Soprano to be too small to comfortably play.  I think the ideal size is where your fingers naturally fall one to a fret at the lowest frets, without having to compress or stretch your fingers.
Lanikai and Kala are the two brands I would recommend picking from.  They're probably the two most common to find in a typical music store and are good quality.  Make sure to get one with machine tuners, the kind where there's a worm gear:
Comment: Pretty hard to find a uke today without machine tuners - the mass-produced cheap ones have them. Having said that, I don't actually see a problem with violin-style peg tuners.
Answer: I always say that a bad first guitar will hold a learner back badly. However I don't hesitate to recommend starting with a ukulele from the bottom end of the market, because:

nylon-strung instruments are more forgiving of cheap construction than steel-strung guitars
they are so cheap -- little more than a round of drinks -- they can be treated as a throwaway purchase

So I say, go ahead and buy one of these very cheap soprano ukes from brands such us Mahalo. These are often the ones painted in bright colours, or printed with fun designs.
Then get learning. This uke will not hold back your technique as a beginner, even though it might not sound as great as a better uke.
Once you can play a few songs, you'll have the experience to know what you find wrong with your cheap instrument.

You may decide that a soprano uke is too small for your hands, and move to a larger instrument in a lower pitch range.
You will probably notice poor intonation on your cheap uke
If you try out a more expensive uke in a shop, you'll be struck by the improvement in tone and sustain.

Depending on the circumstances in which you intend to play, you might also consider an electric-acoustic uke at this point.
Never spend significant money on an instrument without trying it out. Go to a bricks-and-mortar shop, and ask to try out the uke you're considering. Although factors such as the wood used for construction, or the type of tuning heads, contribute to the quality of the instrument, the only really important things are how it feels, and how it sounds (OK, let's admit it, also how it looks).
You'll probably find you'll still want to keep your cheap uke around - because it's fun and colourful; in case someone comes around and you want to try a duet; to take places you don't want to risk your more valuable instrument.
Answer: I would avoid the super-cheap ukes on Amazon having seen the quality of two different ones purchesed by friends.
Based on the one I saw from the first friend, I decided to go up to the $100 range and discovered Outdoor Ukelele which has a poly-fiberglass composite body to give it a more wood-like sound, and I ordered their copper impregnated strings to switch out to when it arrived, wanting to see what the difference in sound was, and assuming it was a gimmick.
So after it arrived, I did some lessons on Yousician with the basic nylon strings it came with. I forget how long I used them for, maybe a month, but when I finally switched the strings out, the difference was amazing.
The copper impregnated strings are minorly affected by temperature but on the whole, the entire instrument is impervious
It's great for camping and boating, which is what it's designed for. A quality wooden one will beat it out, of course, but it sounds way better than the cheap ones from Amazon, comes in multiple colors, and you can even order it with one or two pick-ups installed.


facebook javascript sdk question

Question: I'm trying to use the facebook js sdk to develop an app, but I found the there is 2 version of the sdk, my question, is what is support with the new and what w=not? and if the xdreceive.htm is still needed for the new version, I have read the docs and still can't understand this, can someone with experience in FB can me kind and asnwer me this, thanks for any help!
Answer: I am in the process of converting my facebook canvas app from the old version of the JavaScript SDK to the new version.  I may not have run across all the functionality differences yet, but I'll tell you the ones I have noticed.
First off, xdreceive.htm is not required for the new SDK.  All that is required to initialize the new SDK is the code from the Facebook documentation here: http://developers.facebook.com/docs/reference/javascript/  You can also compare this with the old documentation (I can't post more than one link, so just replace "javascript" in the above URL with "oldjavascript").
One of the main differences between the two SDK's is that the new one uses the new Graph API, while the old one is running on Facebook's Old Rest API.  Facebook is really pushing developers to use the new Graph API and no new features will be added to the old API.
Unfortunately, there are still a few things that you can do with the old SDK that has not been ported over yet.  For instance, there was a method called FB.CanvasClient.scrollTo(x, y) that allowed you to scroll to a spot in the iframe, so that for instance, you could scroll back to the top after a long page.  There is no equivalent method in the new SDK yet.  Also, using the new SDK's method for Dialogs (to publish to stream, etc.) will result in the popup dialog appearing in the middle of the iframe page, which if you have some really long pages in your app can cause the popup to appear off screen, and with no scrollTo method, your users may not notice it.
Basically, there are still a few bugs with the new SDK but Facebook will not be adding new features for the old one and most likely will completely stop supporting and allowing it at some point.  If the issues I mentioned don't seem like a big problem for your app I would recommend using the new SDK as I find it easier to use and to avoid having to recode later.

facebook javascript sdk question


In which market structure does the consumer has almost zero knowledge about the good?

Question: Consider goods that are almost identical (e.g. cement) and require technical knowledge to understand their merit, which an ordinary consumer might not possess. What then is the feature characteristic of its market structure?
Answer: The market for lemons. Paper is here.
The example most commonly given is used cars. The result is market failure.
Comment: I am still unable to find a form of competition, like monopoly or monopolistic competition, in which this feature is quite visible. If you would like to try I think it would be worthwhile for you to consider goods similar to cement whose purchase is influenced by external factors(Builders recommend a certain retailer/brand) and the consumer has very little knowledge about the prices (as it is not a household good) and also cannot gauge the worth of the good (By looking at cement you cannot state its strength etc). Nevertheless thank you for your reply...
Answer: For any given quality of cement, you can charge a higher price per unit because of information asymmetry. There will be a deadweight loss because of this social cost. The consumers in the market can either pay a screening cost to determine the quality of the cement they need, or the firms can signal the quality of their cement if giving that information freely makes them more competitive and take a larger share of the market.
If capacity and output of cement can be easily changed, we'd probably describe this market with Bertrand competition with differentiation (quality). If every firm prices the same, they split the market, otherwise they can undercut the market and take a large share.
$$\text{market share} = \frac{1}{n} + \frac{\theta^\alpha (n-1)}{n}$$
where $\theta \in (0,1)$ is the degree of quality differentiation, $0$ being complete homogeneity, $1$ being monopoly competition, and anything in between being some sort of monopolistic competition. $\alpha$ is just a scaling factor greater than 0. (As well, $n$ is the number of firms competing.)
Comment: Could you please add a reference to an online book article/paper/book from where one can understand the significance of this equation or at least go through its derivation. Thank You.
Comment: I made it on the spot. It's just designed so that at $\theta = 0$, the market share is $1/n$, and at $\theta = 1$, there is no competition, so you get the whole market share for your product. $\alpha$ controls concavity or whatever.
Comment: After recent investigation I found out that cement retailers cannot easily change their capacity, i.e. they will continue to buy, say a 100 bags from the Dealer, and then they are, kind of, forced to sell them. Then which form of competition would you suggest?
Comment: Oh, are we talking about retailers and not producers? I guess then Cournot competition is more appropriate.
Comment: Could you please justify your claim.
Comment: Because that's the major alternative to Bertrand when its assumptions don't hold.


Should I use support or supports with data?

Question:
Possible Duplicate:
Is "data" considered singular or plural?

Which one the following is right grammar
"Limited data support the use of ..."
or
"Limited data supports the use of ..."
Answer: A count noun is something that you can count like the word 'system'. So you could say 'the system supports...' or 'the systems support'.
A mass noun, on the other hand, always takes the singular conjugation, e.g. 'milk is delicious'.
A simple way to tell the difference between a count noun and a mass noun is to ask, 'how many?' or 'how much?' We would say, 'how many systems...?' and we would say, 'how much milk?' The former is a count noun, whereas the latter is a mass noun.
So the question boils down to whether or not data should be treated like a count noun or a mass noun. First of all, data is a plural noun - its singular form being 'datum' but if we classify it as a mass noun we can used the singular conjugation regardless of its plurality. I think it can be argued either way that it could be either a count or a mass noun depending on exactly what you're talking about or who you ask.
These days data seems to be a mass noun (in my eyes). Would you say, 'how much data?' or 'how many data?' If you would say, 'how much data' then you would be treating 'data' as a mass noun which means it should take the singular conjugation (i.e. supports). (
Apparently, both 'data supports' and 'data support' are acceptable however (I read that) some scientific/academic fields insist that you take the plural (i.e. data support) whereas the singular is more commonly used in everyday speech. It is also a question of style and can come down to personal preference. One might even argue that the insistence on using the plural conjugation 'data are' / 'data support' might seem archaic / out-dated.
I personally think that 'data supports' sounds better than 'data support', and I don't think that you would be wrong in using the singular option since data could easily be a mass noun, it reads more nicely and is not incorrect.
A more clear-cut example is the word, 'information'. The word is plural and you would say, 'how much information?' as opposed to 'how many information?' As such we can see that 'information' is a mass noun and therefore takes the singular verb conjugation despite its plurality.
Answer: Either is fine. Data is an established mass noun in English, so generally "data supports" is preferred. The only problem is that you might encounter someone who believes it is incorrect to use "data" as a mass noun and who, incorrectly, thinks there's something wrong.


Is crushing an avocado a chemical or physical change?

Question: Applying pressure can result in chemical changes, does this hold true for an avocado?
Comment: It's physical change, but it can increase the chemical reaction rate as surface area of Avocado is increased.
Answer: I don't think so.  A chemical change implies changing molecular-level structure usually accompanied by transferring electrons.  When you squish an avocado you're only rearranging the fats, carbohydrates, and fiber in it - I don't think a chemical reaction occurs.
If you left it out, and it turned brown (oxidized), that would be a chemical change!
Answer: I second Phillip's answer, which is right in practice, with a small additional detail: it depends on the pressure applied. If you apply pressure by hand, you are not likely to create or destroy chemicals bonds, and the changes will be physical. Applying pressure can change chemical structure, as in the case of solid phase transitions or pressure-induced reactions, but the pressure has to be much larger than that: typically of the order of gigapascals (1 GPa is rougly 10,000 atmospheres).
Answer: Your title and question are a bit different.

Is crushing an avocado a chemical or physical change?

Physical. Crushing (or any other physical manipulation of) any substance is, by definition, a physical change.  However, those physical changes can affect the conditions for a chemical change, potentially causing a noticeable change in the rate of said reaction. You somewhat acknowledge this in your question, though I'm not sure it's quite intentional:

Applying pressure can result in chemical changes, does this hold true for an avocado?

Under reasonable conditions, I'm fairly sure that nothing in an avocado is reactive enough to undergo a chemical change because of any conditions the physical crushing altered. Except that it will increase the surface area and speed up oxidization.  Given enough of a crushing pressure (e.g. equivalent to the pressure put on coal to create diamond) I'm sure some chemical reaction or another will occur.
Answer: The actual act of crushing the avocado (applying simple pressure) is a physical change.  While the act of applying pressure may allow oxidation to happen faster, the application of pressure is still physical.  The type of pressure you would apply to an avocado under normal circumstances would be insufficient to result in chemical changes.  Chemical changes result in the breaking or formation of molecular bonds which are simply not possible by normal kitchen appliances.  Pressure and heat are related which could cause the enzymes and proteins within the avocado to denature, but the act of applying the pressure is not directly responsible for any chemical change in this case, and the application would only be a physical change.  If there were chemical changes, these changes would be caused by factors other than the pressure itself.
Answer: My 5 cents.
In the beginning it's only physical. However if you crush it a lot of things change. The most obvious is that oxygen can penetrate it much easier than before. There are a lot of substances that can be readily oxidated (f.e. unsaturated compounds). You gain bigger surface so the cells on surface will dry. The nice equilibrium in which this fruit exist is changed. I can't explain it on the level of biochemistry but as every living thing avocado must have some mechanisms that protect it from decomposing. Some of them can't work properly if there is not enough moisture and to much O2.


What is the meaning of the expression 熱い胸?

Question: I hear this a lot in song lyrics, and I just can't figure out what a "hot chest" is supposed to mean.
Comment: A good guess might be using the meaning of 胸が熱くなる (https://dictionary.goo.ne.jp/jn/215773/meaning/m0u/) to interpret 熱い胸
Comment: You should have looked up 胸 in a good dictionary first.
Comment: 胸 is chest first. But, 胸 is also heart by context, because the heart is "in the chest". If your "chest is hot" it's because of a "burning passion in your heart", right?

Also, @l'électeur, don't be so curt. That attitude doesn't help people trying to understand things.
Comment: @l'électeur I did. In two different dictionaries. Yes, they do say heart as a secondary definition, but not the first one. Do you blame me?
Answer: As for the definition 胸, it means chest is partially correct. To tell you the truth, 胸 has various meanings besides chest.
In my dictionary, 胸 is defined as:
1. the chest, the breast, the bosom
2. the breasts
3. the heart, the lungs
4. one's heart, one's mind
In the case of 熱い胸, 胸 means neither some organ nor part of the body, but the place where man's feeling is supposed to exist.
"熱い胸":
Literally the phrase means the hot heart, and it means elevated emotions.
In the site shown by binom's comment, there is a sentence "胸が熱くなる", that is a sentence closely corresponding to "熱い胸", which means "someone is moved by something so they become in the state of elevated emotions."


Can one steal data using electric wire?

Question: If I would like to keep my work secret in my computer and I don't use Internet, is it possible for a cracker to steal my data via electric wires or a wireless connection?
Comment: I can use electric wires to connect two telephones, then have an insider speak the secret information into one telephone while I listen to the other one. Does that count?
Comment: so, I would assume your work could be worth stealing. Are you posting this question from your computer?
Comment: Could you clarify what you mean by "don't use the Internet"? Do you mean you won't ever connect the device to a network, or do you mean it will be connected but you won't open the browser, or something else?
Comment: A wireless connection: absolutely, no question.  Power wiring-related stuff?  That's... a very interesting question.  See WoJ's and Corvus B's answers below.  (Although, from a practical standpoint the chances that an ordinary person would be subject to such very high end attacks are very, very low.)
Comment: By "wireless" do you mean through an existing wireless protocol as Blutooth or Wi-Fi, or do you mean straight through electromagnetic waves emitted by your computer? Please clarify this in your original question.
Answer: Yes, this is possible. It is not an easy task, though, and you are not likely to be a target.
There are series of equipment which are shielded so that such attempts are more difficult. They follow sets of standards called TEMPEST.
Comment: Worth adding to this very correct answer: part of being compliant with TEMPEST includes physically observing the wires.  Anyone with physical access can do things that are undetectable without such physical observation.  The TEMPEST enabled systems are all locked in vaults to limit access by third parties, and inspected regularly.
Answer: First of all, a cracker is considered somebody that reverse engineers software in a way where copy protections or nags screens are removed.
From Wikipedia:

Software cracking (known as "breaking" in the 1980s1) is the modification of software to remove or disable features which are considered undesirable by the person cracking the software, especially copy protection features (including protection against the manipulation of software, serial number, hardware key, date checks and disc check) or software annoyances like nag screens and adware.

Technically it is possible that someone could steal your information and/or data if the attacker resides within your LAN. For example for wire tapping, I use the following hardware:

By placing this device in the network, all packets can be captured.
However, this specific hardware is not necessarily required. It is also possible to strip the Ethernet cable and directly tap the RX and TX wires.
From a WLAN perspective, it is possible if someone has access to your WiFi network to put their network card in promiscuous and use Wireshark or a similar product to capture all WiFi traffic. More on that can be found on the Wireshark page: https://wiki.wireshark.org/CaptureSetup/WLAN
Having said that, the likelihood of something happening to you, I consider slim to none. Unless you're really paranoid, disable all your network communication devices (although there are other methods of obtaining information, but this requires very expensive equipment)
Comment: Your use of an article on "cracking" to correct usage of "cracker" is not very convincing and does not match widespread usage. Since the word is ambiguous, however, it might just be better to advise OP to use the word "attacker" that would actually be used in infosec discussions.
Comment: Initially (~'90s) "cracker" was the bad guy and "hacker" someone who was what we would now call a geek. With time "hacker" became the bad guy and "cracker" vanished. So the OP's usage of the wording is correct.
Comment: Indeed, where I work we still use the term "cracker" to mean "bad guy" and "hacker" to mean generally anyone else. Actually, I've seen this use recently only the Erlang mailing list, so its not obscure (any more obscure than Erlang is, anyway). Maybe it is generational; most of us are over 30. This is the meaning I grew up with as well -- and am still sort of weirded out when the mass media states "a hacker stole credit card data". Anyway, warez kiddies are "crackers" indeed, but it is just one form of a very broad spectrum of cracking; one that doesn't appear to meaningfully exist today.
Comment: @R: I agree with attacker, as far as the "cracker" what's the difference between a hacker and a cracker? However, I don't want to start this discussion here as it is completely off topic.
Comment: @zxq9 _mass media states "a hacker stole credit card data"_ Could be that "cracker" has another popular connotation unrelated to computers and it's to avoid any confusion between hackers and Caucasians. Just speculating, however.
Comment: @SourLolita I *seriously* doubt that is why both terms have been warped in media. Another similar case is "Special Forces". That is a *specific* unit in the US Army -- the only unit that actually has Green Berets (hence the nickname). "Special Operations" is the broader category that includes SEALs, Rangers, etc. To the public there isn't a difference, but it annoys me every time I read "Navy special forces did..." since I *was* a Ranger (11B), and then later a Green Beret (18C). I phreaked in the 80's and then later entered hacker culture, so this is similarly annoying -- but whatever. :-)
Comment: Please stop the hacker/cracker spam, it's worthless. Moderator?
Answer: Data can not normally be stolen via your power lines. There is no interface for data transmission between a normal computer and the power line. Hardware is made that can provide such an interface, but someone would have to have physical access to your machine, and install that hardware in your computer. Phone line and power line networking
If you have a LAN, either wired or wireless, then someone on your LAN could
steal data. If your computer has wi-fi, but you do not use it, you can turn the hardware off. At least, you typically can. There might be some computers with wi-fi and no way to turn it off, but I do not know of any. Note that this is not a trivial effort (stealing stuff). Without internet contact you are unlikely to get malware installed by someone else to make stealing your data possible. LAN traffic can be intercepted, but this is again, not easy.
Keeping a computer off the internet is a very good way to keep things private. Locking that computer out of your LAN is even better. For instance, I still run outdated Windows machines for some old software - but I set the firewall to completely block them from using the network. Unless someone gets physical access to them, they can not be hacked into.
Also, of course, good passwords, and encryption are your friends.
Comment: Depends on what you mean by "data".  While isn't possible to pull arbitrary data off the hard drive, [tt's potentially possible to discern keystrokes via power analysis](http://www.networkworld.com/article/2259454/data-center/how-to-use-electrical-outlets-and-cheap-lasers-to-steal-data.html?page=1).  It's also possible to obtain clues as to encryption keys via the same.
Comment: Technically, you have a good point. However, the power analysis still requires hardware installation inside, or close to, the target machine. I honestly felt that adding the "close proximity" modifying clause was TMI and not particularly useful. The laser attack has been demonstrated, but it seems to me it would be exceptionally difficult to use in real life. Not to mention that it could be physically detected by the target's user. I would think burgling the premises and installing a keystroke recorder would be far easier and more efficient. So, TMI again.
Answer: There is a principle called Van Eck phreaking where a receiver is placed near the target machine to collect and transmit the changes in the EMF caused by operating the target device.
Comment: Interesting, nothing some proper isolation can't fix though (like concrete walls and aluminium foil)

Nice to know that this tech is out there though, I was just thinking about it the other day.
Comment: @Cestarian I actually first came across it in the book [Cryptonomicon](https://en.wikipedia.org/wiki/Cryptonomicon) and thought it was just a plot device invented by the author but it bugged me that much I had to research it. Turns out its real.
Comment: Yeah I was thinking about this the other day, or a bit more complex version of it anyways which would scan an area for electrical chips (e.g. in motherboards and smartphones and such) and then read data through them directly (would be hard to do with PCs because of the casings, but laptops and smartphones are mostly isolated with just plastic so easy targets for this kind of thing) I was thinking about it's feasibility, and how to counter it. but I am utterly surprised that similar tech already exists... and there are no perfect countermeasures to it yet.
Answer: No data passes through your power cables, unless you're using HomePlug for your internet connection that is or connecting to another device. It's in theory possible to read your data through tapping your power cable or power supply but it would be so brutally hard to do (next to impossible) that nobody is ever going to try such a thing, literally any other approach would be easier. So it's safe to assume that this won't ever be a worry for the next 100 years at least (possibly for eternity; or at least until power cables and internet cables will be united as one or something like that)
Wireless networking is however ALWAYS hackable either by accessing your router and then using wireshark or something similar to read your packets, or by other more advanced means of tapping your wireless network frequencies technically all unencrypted wireless data is up for grabs since it's literally floating around in the air between your system and your router, and encrypted wireless data while less up for grabs can still be easily hijacked through various means (depends highly on the encryption protocol though how easily, and your router security)
If you are connected to a router or another device with your system, that router or other device which is presumably connected to the internet can be hacked to access your data, if however it is not connected to any other device the only way to hack your data would be physical access, and the only way to keep tabs on that data would be infiltrating the place you keep this device, and secretly insert a wifi or bluetooth device into it and connect it to another device or router for the specific purpose of stealing your  data. (Someone would have to want your data REALLY BADLY, and just as badly want to keep it secret from you that they've got your data... not a likely scenario unless you're someone really special who could be a high profile target because of your social status or job)
In other words a lone pc that is not connected to the internet or another device at all is unhackable through remote means unless it has a wireless networking device installed which could be remotely activated (like bluetooth or some types of wifi cards) so for good measure disable any such devices and nobody without physical access can access your data. Encrypt your hard drives, use complicated passwords, etc, etc and the only way into your system besides you doing it yourself would be this.
Answer: Why are you asking specifically about electric wires or a wireless connection? If I worked for a government, major company, or organised crime interested in your work, these would be quite at the end of my list to get your things. You should describe what you are actually afraid of.
For example: If I wanted to steal your secret, didn't mind hurting you, didn't mind that you know about the theft, and knew that you used say a Mac with full disk encryption turned on, which is reasonably hard to crack, I'd sneak into your house and knock you out while you are using your computer. Well, I'd send someone in who knows how to do this :-) The point is here stealing the whole computer while it is unlocked so I don't need any passwords to unlock it.
If I didn't want you to know, I'd sneak in and install some hardware that records all keystrokes on your computer, and go from there.
It's all a matter of how badly someone wants your secrets.
Comment: This doesn't answer the question. This would work better as a comment.

Can one steal data using electric wire?


Removing App from Play Store (Unpublish) - What happens with the users that have the App already installed?

Question: I have to temporarily unpublish my app from Play Store for legal reason until I sort them out.
What happens with the users that have the app already installed? I understand they are not allowed to find it from the store or install it, but does it also mean the apk they have already installed will be uninstalled from their device?
Comment: Although this is clearly a developer question, I think the answer is of relevance and interest to end users too, so I don't think it should be closed as off-topic.
Comment: When the Hotmail app was replaced with the Outlook app it was upgraded to a defunct app that only directed you to installing the Outlook app. I was however able to re-install the previous  functional version from my app backup.
Answer: No, the application is still available for users who installed the play and only store can not be reinstalled. By Play Store
If you put back the google play, users can download and install it again.
But never, under policies of google, an apk can / will be deleted from the device remotely by google / application owner
But we had a case in the past, about a malicious app that was removed remotely without trace, all done and confirmed by Google itself


Optimal image size for retina - beauty image

Question: We are supporting hi-res displays on our website. We also have large header/beauty images on each page, so I made them 1400px wide - under 350KB - JPGs. I think it's a good balance between quality and size. Our programmers are asking me to downsize them even more. What would be your optimal size for a header image for retina?
Comment: You or your programmer could use https://shortpixel.com to further reduce file size without loosing quality...
Answer: Seems about right
As long as the programmers know how to deal with high-density retina displays, this size (or even slightly bigger) shouldn't be an issue. Of course, as long as we're talking about JPG files like photos with fine details. Otherwise, if your images are vector based, you could (should) use SVG files.
What your programmers seem to be missing is that they need to serve images based on different screen densities. And the whole point of retina screens is to have high quality images with crisp quality, not to save bandwidth.
For example, Apple serves the image below:

Size is 381,47 KB (390.626 bytes)
TheRenovatorHQ doesn't have a differentiation for Retina, so it serves this one for everybody (a retina quality image):

Size is 397,45 KB (406.988 bytes)
And I could go for hours, just 2 quick examples. Please keep in mind THESE AREN'T EVEN THE RETINA VERSIONS (2x the size). However, the second site is an example of what NOT to do: serve high density images to everyone instead of displaying images as needed.
Bottom line is that if you support retina, you're going after quality and bandwidth should be the lesser of your concerns. Showing ultra-compressed images in retina... well, test it by yourself and see what happens. And yes, I fully understand what it means to deal with programmers who can't even grasp the need for high quality images or design or usability or whatever, so you'll need to instill that culture in your organization or you'll have to go through this time and time and time again
Additional Reading
Just as a reference, take a look to the links below and show them to your programmers:

A guide for creating a better retina web
5 Things I learned designing for high-resolution retina displays
Optimize Images for Retina Display
The Right Way to Retinafy Your Websites
Answer: 350KB is too much for a single image and it is not good ballance. As a rule of thumb you should not exceed 100Kb per image (think about people with really slow internet). Suggested density of the pictures for the web is 72 DPI.
Majority of users have laptop resolutions, such as 1366x768. Most used desktop resolution is 1920x1080 which means that picture that is wider more than 1080 pixels is serving not more that 2-3% of users.
Maybe you can do the following: use a 100Kb picture as default, but if you detect user with resolution higher than 1080 pixels wide than use your bigger picture.
Another alternative is to use SVG images which are much more lighter - 1-2KBs at most. They also have perfect clarity in any resolution because they are vector based but eventually they can look pretty cool. The only downside is that someone has to draw them.
To summarize:
Use images that don't exceed 100Kb, not wider that 1080px, with not more than 72DPI. As an alternative use SVG images which are much better than jpg for retina displays.


I need a USB Bluetooth Hub with a decent range

Question: I need a USB Bluetooth Hub that has a range of at least 30 feet.  It should have low latency, at least 3 USB ports, little to no loss of input, and should have great quality with a decent price.  The most I'll pay for is 30$ and I prefer it be on amazon although not needed.  I intend to use this to connect a wired mouse and keyboard to my computer wirelessly.  Any suggestions?
Answer: If I understand the question properly you are looking for a USB hub wich connects to the computer through Bluetooh instead of using a cable, am I right?
In that case such a thing does not exists because Bluetooth is a very slow protocol and would not be USB compliant, not only because of the speed but because of the lattency, causing devices to disconnect intermitently.
I think it would be easier to get a good bluetooth adapter with a bluetooth Keyboard and mouse.
Answer: Tp-link bluetooth 20$, 65ft range.
TP-Link USB Bluetooth Adapter for PC(UB400).
Support Windows 10/8.1/8/7/XP for Desktop, Laptop, Mouse, Keyboard, Printers, Headsets, Speakers, PS4/ Xbox Controllers
Comment: Welcome to Hardware Recs! I believe the OP is asking about a USB hub that can connect over Bluetooth, not a USB Bluetooth dongle.


At what point did Judaism and Christianity diverge?

Question: At what point did Judaism and Christianity diverge? Christianity and Judaism share the Old Testament (The Hebrew Bible), so it should be safe to assume they are the same people at least during the Old Testament period. Since when did they disagree?
Comment: They started disagreeing around one Sunday in May around 30 - 33 AD
Comment: "so it should be safe to assume they are the same people at least during the Old Testament period." I'm most confused by this statement.  Does the author not understand that Gentiles are people from the nations and the Jewish people are distinct because of G-d's calling.  How is it that this became a confused point to the author and perhaps others?  Just because Christians embraced the G-d of Abraham, Isaac and Jacob doesn't mean that Christians were transported in time to become the ancient Israelites.  They are not the same people, that's clear enough, yes?
Answer: tl;dr> It began in the Council of Jersualem (55 AD), but was cemented by the destruction of the Temple in 70AD.

1. Gentiles were released from Jewish custom
The divergence is clearly articulated in Acts 15 - at the "Council of Jerusalem," often pegged at 50 AD - roughly 20 years after the Crucifixion.  Acts 15 sets up the situation as follows:

Certain people came down from Judea to Antioch and were teaching the believers: "Unless you are circumcised, according to the custom taught by Moses, you cannot be saved." 2 This brought Paul and Barnabas into sharp dispute and debate with them. So Paul and Barnabas were appointed, along with some other believers, to go up to Jerusalem to see the apostles and elders about this question. ... Then some of the believers who belonged to the party of the Pharisees stood up and said, "The Gentiles must be circumcised and required to keep the law of Moses."

In a nutshell - it's the old circumcision debate: Do converts need to go under the knife?
Prior to this disagreement, Christians were simply Jews that believed Jesus was the promised Messiah.  When the Messiah came, however, he expanded His mission in such a way as to afford salvation to the Gentiles.  (See Matthew 28:19-20)
Peter speaks to this issue, recalling the fact that the Gentiles were being added to the mission - first in Acts 10, and now again in Acts 15:

6 The apostles and elders met to consider this question. 7 After much discussion, Peter got up and addressed them: "Brothers, you know that some time ago God made a choice among you that the Gentiles might hear from my lips the message of the gospel and believe. 8 God, who knows the heart, showed that he accepted them by giving the Holy Spirit to them, just as he did to us.

That they were included, however, necessarily raised the question of whether or not converts needed to follow all the practices of the Jews.  Peter, Paul, Barnabas, and the other apostles were clear that the grace of God implied that Gentiles need not do Jewish custom.

"It is my judgment, therefore, that we should not make it difficult for the Gentiles who are turning to God.

It was even suggested that a letter should be written, in which they said:

Therefore we are sending Judas and Silas to confirm by word of mouth what we are writing. 28 It seemed good to the Holy Spirit and to us not to burden you with anything beyond the following requirements: 29 You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality. You will do well to avoid these things.

By exempting the Gentiles from the rest of Jewish practice, a separate identity began to form.
2. The Persecution of the Jews diminished their importance in the Church, and vice versa
With the destruction of the Temple 15 years later, it simply became much harder to become a Jew.  As OzTorah writes:

In the post-destruction Jewish community, re-grouping and greater solidarity moved the Judeo-Christian group to the fringes. The earlier latitude towards separatist and fringe groups had become a luxury, especially when the Jesus party increasingly distanced themselves from their fellow Jews. The Judeo-Christians suffered a diminution in numbers and now, though not without an internal struggle, rebuilt and repositioned themselves as an increasingly gentile group, with new adherents directly coming to the new group without having to go through the old one first. They were not a monolithic community; they included at least four sub-groups (Ebionites A, Ebionites B, Nazarenes, Gnostic Sycretists and Elkesaites) – but they, like the Jews, needed to find sufficient unity to plan a secure future.
After much internal debate it became possible for an outsider to become a Christian without ever being part of Judaism, either through genealogy or choice. Could you be a Jew without the Sabbath, festivals, circumcision (Jews were not the only ancient people to view uncircumcision as shameful) and dietary laws? The answer was no – but you could become a Christian. Could you be a Jew without saying Sh'ma Yisra'el – "Hear, O Israel" and proclaiming the absolute invisibility and indivisibility of God? – again no: but you could become a Christian if you accepted the re-worked status of Jesus (developed and taught by Paul and his supporters though not necessarily required by a reading of Jesus' own words) as messianic and part of divinity.
Sharper language than ever before began to be used in Judaism – it was a time of crisis when it was necessary to know where people stood – and heretics could no longer be treated with kid gloves. About the end of the century the Synagogue liturgy introduced a prayer which came to be known as Birkat HaMinim, the Blessing (Against) the Sectarians. ...
There was no authoritative decision to expel the Christians from Judaism but their exclusion came about gradually. The gentile Christians never were part of Judaism. The Jewish Christians still met halachic (Jewish legal) identity criteria but were excluded from officiating at Jewish worship because they regarded Birkat HaMinim as directed against them – whatever its motives at the time of its formulation – and their books were deemed to lack sanctity. In consequence they felt increasingly unwelcome. Christians were still found in the synagogues at least until the time of Jerome in the fifth century CE. In the second century CE Justin Martyr agreed that Jewish Christians who continued to follow Jewish usages were still to be considered "brethren" but as time went on, pressure was exerted to discourage the practice of Judaism by Christians.
The final break was due to the Romans when Jews (including Jewish Christians) were prohibited from entering Jerusalem; the re-established Jerusalem Church was thus an essentially gentile one.

With this polarization, rapid growth outside of Israel (Paul's ministry, in particular, was centered in Turkey and Greece, as evidenced by the fact that Corinth, Galatia, Ephesus, Phillippi, Colossae, and Thessaly all got their own books of the Bible!), and the persecution of the Jews inside of Israel, led to an imbalance of population.
Basically, the "Jews" dwindled and the "Gentiles" grew.  That, coupled with the freedom from the practices of the Jews eventually led to a situation where the church's early identity divested itself of its Jewishness.
3. By the second century, there was hostility
With the firm acceptance of Paul's letters by the end of the first, the anti-Judaizer faction became well entrenched.  By the middle of the second Century, some heretics like Marcion were already trying to remove any vestigial Jewish influence. When Marcion produced his first canonical list, for example, the entire Old Testament was relegated to non-canonical status. (Note - Marcionism is considered heretical nowadays, and rejecting the Old Testament is considered heretical, but I point it as way of evidence that the split had already occurred.)
By this time, "Christ-killer" rhetoric and the like, along with regional chauvinism prevailed, and enmity between the Jews and the Christians was mainstream. Modern Judaism took root in the Pharisitcal and Essene movements and followed its own course thereafter.
Answer: That's fairly straightforward.
Jesus Himself was Jewish.  The divergence came from Him.  Whether it was at His death, burial, and resurrection, immediately afterward, or when He began His ministry is up to interpretation and debate, but it was Jesus, and the New testament (New Covenant) established by Him that marked the split.
Those who recognized Jesus as the promised Messiah were the first Christians.  Perhaps they could have been considered Messianic Jews, but since Christianity is defined as following Christ, following Him is the logical determining factor as to whether or not one is a Christian.  Jews who followed him were, for all intents and purposes, the first Christians, and that's where the divergence lies.
Answer: As David has pointed out, but without detail, the division was with Jesus' life, death, and resurrection. There was nothing that could be called Christianity before Jesus.
During the last three years of His life Jesus gained many followers, however, he never made any deliberate attempt to divide the Jewish faith, nor change it.

17 "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. 18 For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished. Matt 5:17

These are Jesus' own words. He was claiming that the Law (the ancient Hebrew texts) was not to be removed by his coming, but to be uplifted and proven and fulfilled. Jesus was claiming to be a fulfillment of prophecy. The Gospels (Matthew, Mark, Luke, and John) detail Jesus' ministry during the last three years of his life, where he attempted to fulfill Jewish prophecy as the Messiah or the Christ.
However, the Jews of the time rejected Jesus and had Him executed, but that was part of the prophecies. He was disgraced and his followers dispersed. This is also detailed in the Gospels.
Later, however, Jesus' disciples and a few other persons began claiming to have seen Jesus alive. Not alive in that He actually survived execution, but alive in that God had raised Him from the dead and glorified Him. Over the course of a short time many more claim to have seen the resurrected Jesus until He ascended into heaven 40 days (I think) after His resurrection. This too is detailed in the Gospels.
Most theologians would say that it is was this point that Christianity split from Judaism. There were still many Jews who would not believe the resurrection, therefore, there was nothing miraculous about Jesus, but many others did believe, therefore, He became known as the Messiah and the Christ, the One who fulfilled prophecy. Secular historians must neglect the resurrection as fact, however, they do not neglect that Christianity was recognized as from Judaism but different and distinct from Judaism quite early; most estimate that Christianity was well established as a separate religion before AD 200.
According to the Bible the word Christian, which means literally 'small Christ' and means figuratively 'strives to be like Christ', was used very soon after the Resurrection.

The disciples were called Christians first at Antioch. Acts 11:26

The Book of Acts was written to cover the events immediately after the Resurrection to show how Christianity came to be such a large movement then, which continues today.
Summary
Originally, Christianity, as taught by Christ (Jesus), was meant to support and augment Judaism. The Christ came to fulfill the Law. Christianity became something separate from Judaism very shortly after Jesus' Resurrection. The disagreement was whether He was the Christ or not. Christians believe He is and the Jews believe He was not. Because there were many on both sides the two factions were made. The factions persist today for the same reasons, generally speaking.
Answer: In the view of those who follow Christ, Christianity is a continuation and fulfillment of the Judaism of the Old Testament. A certain part of Judaism diverged from that lineage most prominently at about noon on the day Jesus was crucified:

John 19:14-16
14 It was preparation day for Passover, and it was about noon. And he said to the Jews, "Behold, your king!"
  15 They cried out, "Take him away, take him away! Crucify him!" Pilate said to them, "Shall I crucify your king?" The chief priests answered, "We have no king but Caesar."
  16 Then he handed him over to them to be crucified.

Many other Jews, however, did recognize and follow the awaited Messiah. For example, the Letter to the Hebrews was directed to Jewish Christians. This is what the word "Christ" means: Messiah. So "Messianic Judaism" is effectively just "Christianity".
Alternatively, the point at which this divergence occurred was the moment when Jesus was conceived by the Holy Spirit, or when the first or last of the various Messianic Prophecies was fulfilled.
Comment: Well, the last of the Messianic Prophesies are yet to be fulfilled, so ...
Comment: *This is what the word "Christ" means: Messiah. So "Messianic Judaism" is effectively just "Christianity".* - Jesus was not the only Jew pretending to be the promised Messiah.
Answer: Judaism only began with the completion of Babylonian Talmud in early sixth century AD.
The completion of Babylonian Talmud was around 500 AD (Source - Book "Alfred Edersheim: A Jewish Scholar for the Mormon Prophets" by Marianna Rica, Page 44).
Let me give evidences from the Jewish rabbis themselves.
Jewish Rabbi Stephen Wise (Formerly Chief Rabbi of United States) said, "The return from Babylon and the adoption of the Babylonian Talmud, marks the end of Hebrewism and the beginning of Judaism." (Source -Book "The F.O.J. Syndrome in America: Bamboozled Americans and their vile brainwashers", Page 253-254, American Mercury, Volume 6).
"The Bavli [Babylonian Talmud] has formed the definitive statement of Judaism from the time of its closure to the present day." — Rabbi Dr. Neusner (Source - Rabbi Dr. Jacob Neusner, quoted by Norman F. Cantor, The Sacred Chain (A History of the Jews), page 112).
Many people mistakenly think that Judaism is the religion of the bible. This is a fallacious impression. Judaism is not the religion of the bible.
On page 59 of "Judaism and The Christian Predicament," Rabbi Ben Zion Bokser says: "This is not an uncommon impression and one finds it sometimes among Jews as well as Christians; that Judaism is the religion of the Hebrew Bible. It is, of course, a fallacious impression. Judaism is not the religion of the Bible."
Talmud being the holy text of Judaism can be found in the Talmud itself.
Erubin 21b (Soncino edition): "My son, be more careful in the observance of the words of the Scribes than in the words of the Torah (Old Testament)."
Judaism is a reconstruction out of Pharisaism.
"Pharisaism shaped the character of Judaism and the life and thought of the Jew for all the future." (Source - The 1905 edition of the Jewish Encyclopedia says under the subject of "Pharisees").
The Pharisees and the scribes obeyed Traditions of the Elders which nullified the word of God (Matthew 15, Mark 7). That's why Jesus Christ's biggest opponents were the Pharisees and the scribes (Matthew 23, Luke 11).
Traditions of the Elders evolved and finally came to be called Babylonian Talmud which marks the beginning of Judaism as mentioned above.
This is also agreed by Jewish society.
Rabbi Michael Rodkinson - "The Talmud, then, is the written form of that which, in the time of Jesus, was called the Traditions of the Elders, and to which he makes frequent allusions." (Source - The History of the Talmud, Vol. II, page 70, Chapter IX).
Rabbi Herford, in Jewish Quarterly Review, vol 2 (1890) (pp. 454-464) mentions that Oral Torah became Traditions of the Elders and finally to Talmud.
Comment: The full quote from [Erubin 21b](http://halakhah.com/pdf/moed/Eiruvin.pdf) should be given: " My son, be more careful in [the observance of] the words of the Scribes than in the words of the Torah, **for in the laws of the Torah there are positive and negative precepts; but, as to the laws of the Scribes, whoever transgresses any of the enactments of the Scribes incurs the penalty of death.** In case you should object: If they are of real value why were they not recorded [in the Torah]? Scripture stated: 'Of making many books there is no end'." The reason is very important.
Comment: *Judaism is not the religion of the Bible.* - Neither is Christianity, assuming that by Bible you are referring to the Mosaic Covenant.


Why was my edit fixing capitalization rejected?

Question: My edit for a few capitalization fixes was rejected. What was wrong with it?
Answer: Hopefully I can provide some further context as the person who rejected the edit.

The edit did not substantially improve the post. I understand editing to fix spelling mistakes since Stack Exchange search does not understand mistakes unlike Google and find similar words, and I have more than once been frustrated because a post only contains a misspelt version. However in this case, the edits were to capitalisation, which would not affect search.
The edit did not fix everything with the post. This is a key factor when an edit is not substantial — if everything possible is fixed with a post with an edit, then it's more likely to be approved; alternatively, not fixing everything means a subsequent edit is required, adding yet another revision and potentially bumping the post again. (The title didn't need a question mark and was poor, 'The issue is I try', 'and [it] works great', 'won[']t load', et al.)
The edit was made to a very old post which wasn't bumped as far as I could tell. I'm more inclined to approve edits to old posts when they're already on the front page and primarily make edits myself like this.
The edit was one of a string of edits ranging from borderline to unsubstantive to inappropriate. Hopefully this has given you a chance to reflect on some other past edits. The borderline edit I rejected with an edit, have a look at the edit I performed, namely to the title and to the images. The inappropriate edit was inappropriate because it's never right to add useless content to an answer, taking another editor to remove it again adding another revision. The character limit prevents suggested edits like these which just remove a 'hi' taking the time of up to 3 different people on the site to look at a 2 character minor edit.

Having said all that, suggested edits are a great way to get started with contributions on the site and they definitely help the site's readability for the future. I definitely don't want to discourage you from suggesting edits in the future and I look forward to your next edits having made excellent contributions previously. Hopefully this guidance can help everyone become better editors!
Answer: I see this as an edge case. We typically expect edits to be substantial, but this post is very short so it's hard to tell how much better the question reads with some punctuation and grammar.
I could see rejecting that sort of edit myself, but looking at it I've reversed the rejection. Also, that post is already answered, not even you upvoted it once and no one else did until I just cast a +1 and it's 3 years old. Not sure bumping it will do much of anything so I respect the decision to not bump it and react the edit if that was the thinking.
Thanks for posting a question on why.
Comment: However the end result still has grammatical and spelling errors.


SSL-like protocol with public-key hard-coded in the client

Question: Imagine a SSL-like protocol that instead of using certificates signed by a trusted CA, has the server's public key hard-coded in the client.
My question is: what happens if the server's private key is compromised?
Without certificates, the system doesn't have a CRL (Certificate Revocation List) and until the users update the client, the attacker can impersonate the server. How can one build a system that makes public-key revocation possible while having the public-key hard coded in the client?
Comment: The trivial answer is to use a CA and hard code the public key of the CA in the client. I presume you thought of that already, so what is wrong with that solution?
Comment: hardcode a 2nd revocation key into the client?
Answer: If the application completely trusts the public key (e.g., runs code signed by it), then you could add "master key change" messages that can be signed by it, that make the application change it's hard-coded key. For additional security, you could require that the new key be additionally signed by a key hopefully separated from the now-compromised one - here decent options are either an additional more-secured key or confirming the new master key via HTTPS (trusting the CA hierarchy).
Of course in all methods you must ensure the client gets reasonably recent revocation messages - which may require periodic signing of "non-revocation" messages - but note that CRLs have this problem too.


What is Seven-Sided Strike's reach and damage division?

Question: The Monk's Seven-Sided Strike is a focus skill, a series of hits back and forth about a circle. Sometimes I'll see the Monk's animation reach enemies outside the circle. How far does this move reach, and how does it divide the 777% weapon damage over seven hits amongst the targets? If there is one target, does it get seven hits worth 111% weapon damage? Are some hits worth more than 111% (and others less)? If there are seven targets, does every one get a hit or are the hits chosen randomly within the circle (some receiving double, others receiving none)? Or do all targets in the area receive 777% weapon damage? Does the move prioritize enemies within the circle, and how many yards will the move reach if there is no one nearby?
Answer: Each hit does 111% weapon damage, and you hit 7 times.
I'm not positive, but I think each hit is randomly decided among available targets, so although unlikely, you can hit the same target 7 times even if other targets are available. If only 1 target is available, you will hit that target 7 times.
I haven't tested much with the range, so I don't think I can answer that part of your question very well, but if you use the ability on a regular basis you should get a good idea of the sort of range it will hit since there is an animation that shows you who you are hitting.
You do not have to be next to the target to hit them though, and I'm not even sure you need to be targetting anyone to use it. For example, one of the runes you unlock for the skill will teleport you to your target when you use that ability, so I have used it to target an enemy across the screen and teleport there.


What is the best book marketing strategy for an audiobook?

Question: I'm narrator of a new audiobook. What is the best book marketing strategy for an audiobook? I wrote a book marketing article published by an ezine articles, but I wonder if this type of book marketing is really successful.
Comment: You're asking as the narrator; what is the author's involvement?
Answer: I don't have any experience. Here are some possibilities from this website. I hope someone with more experience will answer your question.

Request reviews from audiobook reviewers.
Promote with sites that focus on audiobooks like:
List your audiobook on:Your Website
Share free copies with influences.
Connect with audiobook groups. Here are a few groups to get you
  started:
Comment: I think this groks with my high level understanding of marketing. Get people talking about it is the goal; anything that "hacks" social networks is the winning strategy once a good-enough product is in hand. So find gatekeepers to the target audience and win them over. -- that said op would do better to reach out to marketers than writers. There's some overlap, but not enough to get a good answer on this site.


Asking a question that someone else asked poorly?

Question: Say a user posted a question and made absolutely no effort in attempting to approach the question, so the question receives negative votes, no responses, etc. and I have the same exact question, but I have work to show for my attempts as well as some additional questions about the problem. Should I post the same problem again with my work, or what should I do?
Comment: @Nick Editing someone else's question *to reflect my own progress/effort* is definitely crossing the hijacking line unless it is a wiki question.
Comment: @Nick Hmm, I would say definitely don't do that. That is basically hijacking the question, and would lead to a lot of   problems (say, if a third person decided your version didn't show enough effort, and inserted *his* progress/effort...) Radical additions to a (nonwiki) post by *any* user who isn't the original poster are usually declined.
Comment: If you include substantial work reinforcing your own version, then it deserves its own post. Good luck!
Comment: @Nick Particularly when sub-2k rep, it can be hard to have all the response mechanisms working out as they should. E.g. editing someone else's post is cumbersome. It is admittedly a fine distinction, but answering the question and helping the poster are separate things. To facilitate the latter, a new question is more suitable.
Comment: I would edit the question to reflect my own progress/effort, personally. That would bump it back to the front of the site, getting it the attention necessary for an answer.
Comment: It's only hijacking the question if the edit goes radically out of scope. We're talking about questions of such low quality that they require substantial edit to begin with, or else face deletion.
Comment: This [meta question](http://meta.math.stackexchange.com/questions/18883/how-can-i-improve-another-persons-answer-beyond-the-scope-of-an-edit) I asked is very related (it just regards answers instead of questions)
Comment: Note that duplicates are judged based on answers. If the original question does not have an answer, you're not creating a dupe. Just go ahead, post your question and when any of the two gets an answer, close the other one as a duplicate. I'd definitely avoid hijacking the original answer.
Comment: @Nick But sure, there are cases when substantial edits can improve the quality of a question.
Answer: If you include substantial work of your own for the question, then it probably deserves its own post since the answer becomes more focused on picking up where you left off.
If you have exactly the same question and nothing to add, then you might post a comment saying so, and consider offering a bounty (if you can afford one.)
Just keep in mind that readers usually do not like posters who haven't done due diligence in searching. But if what your asking truly hasn't been addressed before, then there is nothing wrong with doing your best to write it up in a new post.
Good luck!
Comment: I agree with this, largely because I find myself in this exact spot quite often. Usually, the previous asker simply asked the question, and never followed through when given hints rather than outright answers.
Comment: It's even worse when someone ask a general question in this question-title, but then really only wants to know some very particular answer to a very particular case (or example/application). Such titles often end up being clickbait of no real use for most other readers. To paraphrase an example, the title might ask: "is there an algorithm to solve diophantine equations?" But the in the body of the question we find out s/he just wants to solve $x+y=3$.
Answer: This is very close to what rschwieb wrote, but since it is already written...
I assume the other post has no answer, and also not much other substantive discussion on it.
It depends a bit how old the other post is.
If it is very recent, say, less than one or two weeks old, I would wait to see what comes of the other post.
If it is older than that go ahead and just post your own question.
I would still add as a side remark, perhaps as a comment, the information that you know about that other post to avoid others directing you towards it and to deflect any  impression you might be OP of the original and trying to ask the same question for a second time.
There are various advantages in you being OP (in having an active OP) of the question, such as you can accept an answer, you get notifications, etc.
Answer: This is a question/answer website, not a "solve my math problem" website.
So even if your math problem is the same problem, since you posted your work:

The original post's question was a math problem
Your question is where to continue with your own work

So you clearly have a different question.  Which is why I would support making it a new post.
Comment: In view of the existing answers, this one is entirely useless. -1.


Differences between Excel 2003 and 2007 from a VSTO perspective

Question: What are some of the major differences to be aware of when developing Addins or Document level customizations for excel 2003/2007?
Answer: A couple items:
VSTO 2SE - can be used for both Excel 2003 and Excel 2007 addins.  (requires code-access security on installation)
VSTO 3 - can only be used for Excel 2007 add-ins. (Does not require code-access security)
Excel 2003 - can install add-in for all users or per-user.
Excel 2007 - Can only install add-in per/user.
Answer: FYI.  The blog article mentioned above is not accurate in document level customizations.  Perhaps at the time it was, but it is no longer accurate.
Excel 2007 Document Level Customizations are fully supported in Visual Studio 2008 however they utilize Visual Studio Tools For Office 2007 (aka VSTO 3.0).