What prevents MOSFET drain-to-gate leakage current?

Question: What in the structure of a MOSFET prevents leakage current flowing from the drain to the gate of a MOSFET when the drain is at a higher potential than the gate? I am assuming that drain-to-gate leakage current doesn't exist at all because it seems to me that if it did it would be a central MOSFET datasheet parameter as this current from the drain could charge the gate and turn the MOSFET on. If however drain-to-gate leakage does occur as a very small current, what keeps it from ever being a consideration in circuit design or in component evaluation?
Answer: I'm answering the question of how a power MOSFET can let you have e.g. a 500V Vdg while Vgs is limited to 20V.
Power MOSFETs have an asymmetric vertical structure, like this:

The breakdown voltage is determined by the characteristics of the N region between the drain and gate. The maximum current is determined by the size of the channel. In a vertical MOSFET, these can be varied separately, so you can have both a high on current and a high breakdown voltage.
Answer: There are two familiar cases here:

The usual integrated circuit (IC) case, where lateral MOSFETs are formed, covered in gate metal/oxide, over the whole channel;
Power MOSFETs, which are made in more compact/highly optimized structures, offering much higher voltage ratings (silicon parts are available rated 2500V or more!).

The other answers have covered #1 more or less, I think, and this is perhaps the less interesting case: in ICs, Vgs and Vds are almost always only within VDD to VSS.  It doesn't really make sense to think of leakage from a channel that's not higher in potential than the gate anyway.*
So I also suspect your question may be more angled towards #2.  Note that IC-style MOSFETs are essentially unavailable as discrete components -- almost any MOSFET you see on a board, will be some type of power MOSFET.
And as for power MOSFETs -- There is a fairly obvious(?) disconnect, I think, between the usual cartoon of a MOSFET (gate lapped over the whole channel), and a power MOSFET that obviously is handling a whole hell of a lot more than the, whatever, 20V say that the gate oxide is rated to handle!  So what are they doing?
Two things.  Back in the bad old days, when MOSFETs were still new, lateral MOS was indeed still the technology of the day.  To handle the higher voltages, gate metal simply wasn't deposited over much of the channel length; instead, a heavier oxide layer, and a "field plate", tied to drain, was placed there.  This effectively biases that part of the channel on, but with much less gain (read: less electric field per volt -- again, thicker layer), and so voltage can distribute along the channel, well, if not better necessarily, then differently at least.  (I'm not sure exactly what designs they did of this; it would also make sense to have a tapered oxide under the field plate, but I don't know that any stereolithography process has ever made a sloped oxide surface; that would be very difficult to fab the usual way, at the very least.)
I don't know enough about laterals, to say what kind of ratings they achieved; maybe a couple hundred volts?
Note that, meanwhile, the channel diffusion itself is deeper, lighter, less abrupt -- just as the case for a higher voltage diode or BJT.
I was about to explain modern vertical (VDMOS) here, but I see @AdamHaun has beat me to it!  In that case, the voltage is dropped across the p- epi, and, I suppose the oxide at the bottom of the trench could be thicker, though I don't know that that's done..?
Anyway, the structure very much resembles any other high voltage device -- diode or BJT -- where there's a large drift region of lightly doped (sometimes intrinsic even, as for some rectifiers -- though I don't think transistors can use intrinsic, so, not quite that low doping) semiconductor, across which most of the voltage is dropped (depletion region), and then there's a tiny bit of hardware at the surface, shooting charges (electrons/holes) into that depletion region.
The figure (https://i.stack.imgur.com/c3pBM.png) I think is not to scale; the gate stuff is actually all very small, i.e. 100s nm wide, and perhaps a few times taller (not sure of the exact dimensions; and it does vary with process of course), while the drift region is several to 10s of µm tall.  So this allows the electric field to drop mostly through the bulk, without building much additional E-field at the base of the gate trench, so that breakdown (avalanche), when it does occur, doesn't cause too much stress around the gate, which might lead to failure.

*There is a different gate leakage mechanism, known as "hot carrier injection".  I'm not real big on the details of this myself, but it has to do with operating a transistor very near its process limits (close to breakdown); the high electric field accelerates the carriers crossing the channel (i.e. raising to higher energy levels: hence "hot"), and these high energies being generally present in the area, allows some to tunnel or diffuse into nearby structures -- even through fairly high energy barriers, like SiO2 (an insulator, i.e. electrons don't move very far through it normally!).  This phenomenon allows depositing charge into an otherwise fully unconnected piece of metal placed near/on the channel: thus a floating-gate EPROM cell can be formed.  The deposited charge, of course, biases the gate, so that when normal gate voltages are applied to the second (wired) gate, the transistor may read as on or off, and thus a bit of information can be stored, persistently.  This usually needs similarly drastic means to relieve the charge -- UV exposure for example (photoelectric effect) -- but electronic methods have also been developed, hence EEPROM and Flash.  (I've not read up on these in a long while, actually, so I will hold off on attempting an explanation; others can chime in.)
The significance of this effect, can also be seen in MOSFETs: at high Vgs (above ratings), carrier injection can occur due to the few carriers that do leak across the barrier; if they get stuck, a permanent shift in Vgs(th) results.  Of course, if too many get stuck in one place, a defect can form; or if too many flow in a local region, same idea, and gate rupture occurs.  Vgs(max) is rated to avoid both effects.
Likewise, the hot-carrier (channel) effect can cause shift in Vgs(th), or eventual failure.  While many MOSFETs are rated for avalanche robustness, take care that those ratings are indeed one-time -- typical parts only survive a few such hits before destruction.  And repetitive avalanche can cause incremental wear, by trapping charges in the oxide.  This is why I always recommend control of Vds: if it cannot be ensured in normal operation (e.g. with adequate supply bypass, design of the switching loop, etc.), then a clamp diode or TVS should be added to sink the excess, avoiding avalanche operation.  (TVS diodes are made with careful control of trapping sites, so can withstand essentially unlimited avalanche.)
(Supposedly, some MOSFET types are more robust than others, in terms of repetitive avalanche.  But I haven't seen a good argument for why this might be, or how to identify them.  One explanation could be, avalanche is made to occur in the space between gate trenches, so the hot carriers are relatively distant from it; but I don't know what families, if any, have such a feature.)
Comment: As far as I understand the bottom of the gate trench doesn't need to have thicker oxide because, when off, the bulk of the drain-source voltage is dropped over the *drift region* and not over the channel.
Comment: This is a great answer; much better than mine, I think.

Regarding EEPROM/flash erase: In the flash memories I've worked on, erase (removal of electrons from the floating gate) is done using Fowler-Nordheim tunneling. A very high voltage (on the order of 15-20V) is applied between the control gate and the body, causing the trapped electrons to tunnel through the oxide. NAND flash also uses F-N tunneling for programming by applying a high voltage in the reverse direction.
Comment: @AdamHaun Ah yeah, zap the channel to write, zap the gate to erase, that makes sense.
Answer: The drain to gate (and source to gate) resistance comes about because of the 'O' in 'MOSFET'.  This drawing (By Brews ohare - Own work, CC BY-SA 3.0) shows a schematic of the MOSFET structure.

The pale layer between the gate (G) and the channel (between the source and drain, S and D respectively) is insulating -- in a silicon device, it's silicon oxide, so it's basically glass or quartz.  That layer is a good insulator.
This doesn't mean the insulation is perfect - any two electrical conductors will leak a little bit.  In the case of most discrete MOSFETs, the leakage is utterly insignificant compared to the intended usage of the part.  Most MOSFETs are intended as power devices, and gate drives need to have very low impedances to drive the gate quickly enough.
If someone were selling you a FET where the isolation between the gate and source or drain is a selling point, then they'd be sure to tell you -- and they'd have recommended board layouts for you because when you get to that point the board can potentially leak more than the part itself.
Comment: What makes the drain-gate leakage so much smaller than the gate-body leakage, then? Gate-body leakage is often listed in datasheets as being in the 10s of uA. Vdg is in most use cases much higher than Vbg so if the oxide-as-resistor model were valid here the current between the drain and gate contacts would be higher than that of the body and gate contacts, no?
Comment: @mamawmaw if a datahseet gives only a max value and no typical value (especially for leakage specs), such as max. 10 uA, that means: 1) design your circuit to tolerate 10 uA leakage 2) they give a large value, so they can skip the cost of production testing 3) the actual value is likely orders of magnitude lower.
Comment: Could you _edit your question_ to include that vital bit of information?  You're getting beyond my knowledge of FETs -- I buy little black things with three or four contacts, and I design boards around them.  It sounds like you might be speaking of MOSFETs inside of ICs?
Comment: Yes I will edit the question. Its only through your response and the others that I am able to better articulate my question, so thank you, I do value your feedback a lot.
Answer: There is an insulating oxide layer between the gate and the source/drain structures. As long as you don't apply a high enough voltage to breakdown that oxide layer the leakage current flowing through it should be extremely small (nanoamperes, for example).
Comment: The question of why the gate-to-drain breakdown voltage is so much higher in a typical MOSFET than the gate-to-source breakdown is one that might be worth answering as well, though I don't have the time to answer it myself.
Comment: Yes but couldn't even these nanoamps tunneling through the oxide from the drain charge the gate? I guess my question is then what parasitics (resistances to ground, for example) of the MOSFET keep the capacitance at the gate from being charged to an arbitrarily high voltage by the current tunneling through the oxide?
Comment: The gate will typically be connected to some other circuitry that can supply much more than nanoamps and thereby maintain the gate voltage at the appropriate level. If you just leave the gate unconnected then yes, the leakage current could have a noticeable effect, but nobody does that in practice.


Difference between erga and quoad?

Question: In medieval Latin, is there a difference between erga and quoad? They both seem to mean "with respect to".
Answer: quoad is only an adverb when it means 'as long as'. When, like ergā, it governs a noun in the accusative, both are prepositions, but they have different meanings.
quoad limits the application of some assertion or introduces the topic for a following assertion. It's composed of the directional quō 'where to' and ad, which designates a limit.

It's only an adverb when it designates a limit in time and translates to 'as long as (not), until', as in your last example (quoad eijus vīta terminētur); or, with licēre and posse, a limit of ability, 'as far as, as much as'. These are its most common uses.
In your Aquinas excerpt it's a preposition whose function is likewise limiting or specifying: there are three elements of Sin, and Extreme Unction is said not to remit any of them: 'Sin limited to Stain without Contrition, Sin limited to Punishment, or Sin limited to its Remnants.' It can be understood as a reverse genitive: 'sin as far as its stain => sin its stain => the stain of sin'. This construction is actually grammatical in some varieties of English.
Its other major use as a preposition is disjunctive: quoad hoc quod compertum est, dīcit... 'as regards what has been uncovered, he says that...'. Here it establishes (when preceding) or circumscribes (when following) the topic of discourse.
These latter two uses don't depend on any verb and are characteristic of late and especially medieval Latin. Classical Latin uses quod ad X (attinet), quantum ad X (pertinet) and especially dē for the topic-limiting disjunct, and the specifying meaning would be expressed using genitives, adjectives or a relative clause.

ergā has a totally different meaning and expresses the object, and especially the person, whom a (usually good rather than bad) attidude or a state-like action is directed towards: nihil ergā eōs agere 'to do nothing in relation to them', amor ergā parentēs 'love towards one's parents'. It has no adverbial or disjunctive uses, but is a pure preposition that depends on some (de-)verbal part of speech, similar to in and antonymous to contrā, with adversus somewhere in the middle.
I can't think of instances where the two are interchangeable.
Answer: Erga is a preposition; quoad is an adverb.
Roy J. DeFerrari, A Lexicon of St. Thomas Aquinas, p. 370:

ergā, prep. with acc., in general of every kind of mental relation to a person or thing, to, towards, in respect to.

Eliguntur homines ad aliqua officia vel secularia vel ecclesiastica; ab his qui nihil erga eos agunt*, PS. Q. 13. Art. 4 ob. 3 […]

*Freddoso transl. PDF p. 1036: "Men are chosen to certain offices, whether secular or ecclesiastical, by those who do nothing with respect to them."Alt. transl.: "men are chosen for certain posts, whether secular or ecclesiastical, by those who exercise no action in their regard [or 'regarding them']."
p. 932:

quoad, adv., (1) with respect to, as to = quod attinet ad (with the acc. only, in the S.T.), (2) till, until.

(1), sed per extrema unctionem non remittitur peccatum quoad maculam sine contritione, quae etiam sine unctione remittit; nec iterum quoad poenam, quia adhuc si convalescat, tenetur perficere satisfactionem iniunctam; nec quoad reliquias culpae, (ob. 2) […] PTS. Q. 30. Art. 1

[…]

(2), et similiter de homine aliquo iudicium perfecti dari non potest, quoad eius vita terminetur, eo quod multiplicia potest mutari de bono in malum, aut e converso, PT. Q. 59. Art. 5 c.

Difference between erga and quoad?


Is it recommended to file joint tax return if married to a tax exempt person (UN employee with G4 visa)?

Question: I am trying to figure out if it makes sense to file my taxes jointly with my wife if she is tax exempt. I haven't found much information on the web that deal with such situations but I heard from friends and colleagues that it may advantageous to file jointly as the Tax-exempt individual (spouse) would report 0 taxable income.
Answer: Honestly in most situations like this, I suggest filling out the forms both ways and finding out which gives you the lesser tax burden, as an individual answer would require knowing your full circumstances such as your income and deductions and credits which apply to figure out what would be best.
In many cases married filing jointly does give more opportunities to save but it is very difficult to guess in an individual case.
If you use software to file your taxes many products offer the ability to take your information and tell you the refund you would get with each filing status, which takes some of the pain out of entering everything twice.
TLDR:
Try both and find out for your individual circumstance.
Answer: One potential issue I see with filing jointly is that it will make her a resident alien for tax purposes. In G status, she is an "exempt individual" for being an employee of a foreign government or international organization. This means that her days in the US in that status are not counted in the Substantial Presence Test, so she doesn't pass the test, and she is a nonresident alien for tax purposes.
However, nonresident aliens cannot file jointly. To file jointly, you would have to use the Nonresident Spouse Treated as Resident election to make her a resident alien for the whole year. I don't know which specific tax treaty or provision exempts her income from US tax, but that provision might only apply to nonresident aliens, in which case making her a resident alien would get rid of her exemption. (But some tax treaty provisions apply resident aliens too, so you have to check.) Also, resident aliens are subject to US taxes on their worldwide income; I am not sure whether the tax treaty provision would also exempt her non-US income.


Distribution of eigenvalue spacings

Question: I have been doing some experiments on classes of random matrices, and it seems (visually) that the distribution of eigenvalue spacings is consistent with GOE or GUE or GSE. Unfortunately, to test this, I would like to (a) be able to generate GOE/GUE/GSE spacing variates (I suppose I COULD generate very large Gaussian matrices and compute their eigenvalues, but this seems not very fast...), or even have some formula for the distribution function (there is the Wigner surmise, but it is not quite accurate). There are horrible-looking formulas in Mehta's book, but they don't seem usable, somehow. Algorithms/code must exist somewhere -- any pointers would be appreciated.
Comment: It is known that the GOE spectral distn is the same as that of a tridiagonal random matrix whose off-diagonal entries are square roots of chi-squared and whose diagonal entries are standard normal - would it be any quicker to sample from these and then use some off-the-peg code to compute the eigenvalues from the tridiagonal form?
Comment: For the details written out, see section 4.5 of this book: http://www.math.umn.edu/~zeitouni/technion/cupbook.pdf
Comment: @Yemon that could certainly help a lot, but I wonder what you mean by "the same". That is, it might be that the limiting distributions are the same, but one needs to know some explicit bounds on the speed of convergence to make this computationally useful. Is anything like that known?
Comment: In Yemon's comment, "the same" means literally the same for matrices of any size, not just asymptotically.
Comment: As Mark says (you just tridiagonalize the given symmetric matrix, using e.g. a sequence of Householder reflections). I rediscovered this some years ago, but I think it is in a paper of Trotter from the 1970s, and has probably been independently observed in several places.
Comment: @Yemon + @Mark: that's very interesting, I will check out the refs...
Comment: @Igor: if you don't mind the writing style of an inexperienced semi-graduate-student, see also Section 3.3 of http://math.usask.ca/~choi/pubmath/part3ess/EssayFin.dvi
Answer: I suggest you to take a look at the paper "How to Generate Random Matrices from the Classical
Compact Groups" by F. Mezzadri, Notices AMS 54 (5), 592-604 (2007). Can be downloaded freely from here:
http://www.google.es/url?sa=t&source=web&cd=1&ved=0CBcQFjAA&url=http%3A%2F%2Fwww.ams.org%2Fnotices%2F200705%2Ffea-mezzadri-web.pdf&rct=j&q=How%20to%20Generate%20Random%20Matrices%20from%20the%20Classical%20Compact%20Groups&ei=W-BNTb6nFZaShAfS2bWTDw&usg=AFQjCNESHv00uIyATuY1NETwTfH5IO1fhQ&cad=rja
Comment: @Andrei: this is a very cool/useful reference, but unfortunately it does not quite answer the question, since my question is equivalent to randomly generating spectra of symmetric or hermitian matrices, so generating random (eg) unitary matrices does not seem to help...
Answer: If 2% accuracy is sufficient, then you can just use Wigner's surmise. It is unlikely you will be able to beat that accuracy by generating random matrices and sampling the eigenvalue spacing. If higher accuracy is needed, you can find the spacing distribution by numerical integration of a Painleve differential equation, see Forrester & Witte arXiv:math-ph/0009023
A tabulated solution is in Haake's book "Quantum Signatures of Chaos", that is probably the easiest way to go.

Distribution of eigenvalue spacings


Why was Bill Turner called Bootstrap?

Question: In the Pirates of the Caribbean, why Bill Turner was called "Bootstrap"?
Comment: Maybe he removed them?  Added extra ones?  Left them untied?
Comment: Maybe he had to compensate for something so had extra big ones. :)
Comment: Good man. Good pirate. Very *responsive.*
Comment: He was the one founded **Bootstrap_(front-end_framework)** And he was very responsive. (https://en.wikipedia.org/wiki/Bootstrap_(front-end_framework))
Answer: As described in the Pirates of the Caribbean wiki, at the start of William Turner Sr.'s career, he was simply Billy Turner. Since Billy is not a 'fit name for a pirate', he was named Bloody Bill Turner.
It wasn't until he assisted Barbossa in the mutiny and then turned on the mutineers by sending his son a single piece of eight, thus ensuring their everlasting torment by curse, that Barbossa has his crew tie Bloody Bill to a cannon by his bootstraps and tossed him overboard; thus changing his non-de-plume to Bootstrap Bill Turner.
Comment: Bootstrap was named as such before the incident you mentioned. also he didn't **assist barbosa for the mutiny**. that's why they tied him onto canon and shot into the sea
Comment: Well that just seems like an awful waste of a perfectly good cannon!
Answer: We don't know.
In the first Pirates film, The Curse of the Black Pearl, Jack Sparrow and Will discuss Bootstrap Bill Turner:

William Turner: You knew my father.
Jack Sparrow: I knew him. Probably
  one of the few who knew him as William Turner. Everyone else just
  called him "Bootstrap" or "Bootstrap Bill".
William Turner:
  "Bootstrap"?
Jack Sparrow: Good man, good pirate. I swear you look
  just like him.

Bootstrap Bill did come to his demise by being tied to a cannon by his bootstraps and thrown overboard, but the conversation between Jack Sparrow and Will Turner above strongly implies that the manner of his death was because of his nickname, rather than what led to his nickname.
In other words, he was called Bootstrap Bill before that incident.
So where did Bootstrap actually come from? We don't know. We have never been told.
Answer: It's because of the way he died.
At the very least, it is used in the story "just because" in order to remind us of the way he died.

Pintel: So, what Barbossa did is, he tied a cannon to Bootstrap's
  bootstraps.
  Ragetti: [snickering quietly] Bootstrap's bootstraps...
  Pintel: And the last we saw of ol' Bill Turner, he was sinkin' into
  the crushing black oblivion of Davy Jones' Locker. Course, it was only
  after that we learned we needed his blood to lift the curse.
  Ragetti: Now that's what you'd call ironic.
  [Ragetti and Pintel laugh]

This conversation:

William Turner: You knew my father.
  Jack Sparrow: I knew him. Probably
  one of the few who knew him as William Turner. Everyone else just
  called him "Bootstrap" or "Bootstrap Bill".
  William Turner: "Bootstrap"?
  Jack Sparrow: Good man, good pirate. I swear you look
  just like him.

may suggest that he was known as "Bootstrap" before his death, but it also just reinforces the idea that Jack was one of the few who respected Will Turner and that Will Turner was the only one aboard the Black Pearl who did not agree with the plan to mutiny Jack. There is no answer for this apparent inconsistency.
Answer: I'm of the opinion that bootstrap got his name due to being first mate and old maritime humor, as in "he is that far up the captain's behind ,all you can see is his bootstraps". That would explain why Jack doesn't call him that and the childish sniggering when it's mentioned
Comment: Do you have any evidence to base this claim on? Is that "all you can see is his bootstraps" bit even a real piece of old maritime humor, or just something you came up with? This sounds more theoretical than verifiable, but I could be wrong.
Comment: Well its better than brown nose bill

Why was Bill Turner called Bootstrap?


Is it true that Yahweh was part of a polytheistic religion?

Question: I remembered recently that long ago, in middle school, my history teacher told us in the class that Yahweh, the Hebrew God was a god part of a polytheistic religion, and that He wasn't even the king of gods(like Zeus from Greek religion), and that Abraham choose Him(Yahweh) from the other gods to be the all-mighty, all-knowing, all-powerful, single God to his new monotheistic religion, that he passed to his son Issac and his grand-son Israel and it became the God of Israel nation and trough Jesus(who was part of the Israeli nation, kingdom of Judah), it became God-The Father for us, Christians. This sounds like a blasphemy to me, but is this based on any historical discovery, or has it any theological or historical veracity?
Comment: I don't have a definitive answer, but it sounds like the sort of apocryphal story you'd get from someone trying to deny Christianity. Certainly it is completely inconsistent with Scripture, and given how well Scriptural, even the very earliest parts of Genesis, matches with science and archaeology, I'd say it's extremely unlikely.
Comment: Perhaps some polytheistic religions expressed belief in Yahweh.  That does not make Yahweh a polytheistic God however
Comment: @NigelJ, "is there any precedent/credence to this claim I came across about Christianity?" seems perfectly fine. Difficult to give a negative answer, perhaps, but I see no cause to declare it opinion-based or off-topic.
Comment: @Archaeology has uncovered similar words for "god" in Canaan land (Hittite to Egypt). But I think they were _El_ and _Elohim_. Will have to look up my sources. These are generic names though, and not  _revelatory names_ as that given to Moses specifically.---Note that Moses wrote Genesis, so that the use of YHWH in the early chapters would be anachronistic in a reasonable manner.
Comment: So do you say that since Abraham lived before Moses, and Moses wrote Yahweh first, Abraham never used Yahweh(YHWH) because he didn't know this name?
Comment: No, it is not true. And, agreed, it is a blasphemy. I have voted to close this question as it is a matter of opinion and is, in my view, off-topic on a 'Christianity' site.
Comment: @Bogdan-*I appeared to Abraha, to Isaac, to Jacob, as God Almighty (El-Shaddai), but by my Name the LORD (YHWH) I did not make myself known to them*. (Exodus 6:3). Just what this means is debatable.  But previous usage by Moses in writing Genesis I take to be anachronistic. Peace.
Answer: In ancient times, to know the name of a god gave the worshipper access to its power. By calling a god's name, its presence could be assured. Yet the God of the Old Testament expressly forbade using his name in such a semi-magical way (Exodus 20:7). Neither is his name something to be discovered and manipulated by people; it is revealed by him to his people, to be revered. In Hebrew, the name of God is spelled:
יהוה In English, that transliterates as YHWH. In modern Hebrew, YHWH is pronounced "Yahweh." The English transliteration of YHWH is "Jehovah," which we get via Latin.
It's relevant to this question to know subtle differences in pronunciation of the divine name, to avoid inferring pagan ideas, or mixing it up with pagan deities. The name 'Yahveh' is NOT a pronunciation of YHWH. That's because according to the Talmud, Yahveh is the name of the Archangel Metatron, who because of his extreme Godliness, was given a new name by God that was almost the same as God's:
יהבה Those letters are transliterated as YHVH into English and the name is pronounced "Yahveh" in Hebrew.
The letter ו in Hebrew, the third letter in the name יהוה (YHWH) since Hebrew reads from right to left instead of from left to right, is the letter vav. Like many English letters, many Hebrew letters have more than one pronunciation. The letter vav is one of those letters and is pronounced either as a V or as a W, but in a few words, it is used to indicate the vowels O or U. Hebrew generally doesn't use vowels, but every once in a while it does, and when it does, it's some consonant that's being used as a vowel. In YHWH, the vav is always pronounced as a W: "YahWeh." It can't be construed as being pronounced as a V because of the name YHVH or "YahVeh" whose third letter is ב or bet. While the letter bet can be pronounced as either a V or a B in Hebrew, it is only ever pronounced as a B when there is a dot in the middle of it: בּ. Without that dot, it's always pronounced as a V. Since YHVH in the Talmud is stated as being very much like but still different than YHWH, the actual name of God, the vav in YHWH is always pronounced as a W and not a V or else the two names would be pronounced exactly the same and thus contradict the Talmud's teachings. These details show how easy it would be to misunderstand a name written in ancient Hebrew, thinking it was Yahweh, when it was actually that of (in this case) a created angel, Yahveh.
However, there's more to the matter of whether Yahweh was part of a polytheistic (hence pagan) religion, or not. The patriarchs are said to have worshipped a deity some think of as 'the God of the ancestors'. One Hebrew word for ancestor is rishon but only occurs once in the OT, in Leviticus 26:45, where it speaks of the covenant of the ancestors. The word aboth is quite common, meaning 'fathers, ancestors', and, as in Exodus 3:13 & 15 & 4:5 comes the phrase, "the God of your fathers" (or, 'ancestors'). Let me now quote from this scholarly book (when the author was Lecturer in Religious Studies at the University of Stirling, and had presented several religious programmes on television in Scotland.)

"The research of Albrecht Alt has shown that the worship of gods
identified as 'the god of my father' (that is 'the god of the
ancestors') was widespread among many tribes in the ancient world. We
also know that the name 'El' was widely used as a name for local gods.
In Canaan itself, the Ras Shamra texts depict El as the father of the
gods and head of the pantheon at Ugarit..." Old Testament Faith, p.
38, Lion, 1986

Drane then says there are two ways of explaining this:

"Some (notably O. Eissfeldt and R. de Vaux) argue that worship of El
and worship of Yahweh were originally quite distinct and separate...
Professor F. M. Cross takes a completely different line, arguing that
all these names (and others) used for God by the patriarchs referred
to the one deity  later called Yahweh. To speak of 'the god of the
ancestors' was, in his view, just another way of referring to El, and
'Yahweh' was the way to address this one God in the context of
worship. Cross's position is certainly closer to the theological
stance of the Old Testament itself... (Ibid.)

Drane then goes on to say that the Israelites knew that Yahweh did much more than the Canaanite god El was ever supposed to have done. Yahweh was the God of the exodus, and had been the guiding force in their lives from the very beginning.
That what your history teacher told you sounded like blasphemy to you is unsurprising, given that Yahweh declares himself to his people to be the only true God; that all other claimants are false gods, no-gods, would-be-usurper-gods; that the idols of the nations surrounding Israel are lumps of metal, stone or wood, with no ability to see, to hear, or to do anything. The prophet Isaiah repeats that frequently, as do all the Old Testament prophets of the living God, Yahweh. So, my simple answer is, "No, Yahweh was never part of any polytheistic religion; he is utterly unique, the one and only Creator of life, light and eternity."
Comment: I think I understood, there is a similar situation in my language. The word we use for God is "Dumnezeu", formed from "Dumne" + "zeu", now the word "zeu" obviously comes from the ancient greek mythology, where *Zeu*s was the king of gods. The name Zeus was transformed to "zeu" which became in my language a common noun used for any deity. For example Posseidon is a "zeu", Egyptean Anubis is a "zeu". But, when the Christianity came, with its monotheistic theology we added the "Dumne" - prefix which means "lord"(it is used as "mister" for humans) [The comment continues down]:
Comment: And the prefix "Dumne" which would translate as "Lord" or even "Mister" which individualize the "zeu", smh like: the Christian God is not any god, is The God, The Lord God. In a way this is a similar situation of what you explained, that the common cannanite god who was a god worshipped by many tribes was identified with YHWH. But that doesn't mean YHWH take the polytheism character from that common god. The situation that I explained is similar, because even if the name we use from God comes from Zeus's name, that doesn't mean we worship the Greek god, who is part of a polytheistic religion
Answer: It is true that there is evidence to suggest that the worship of Yahweh, the God of the Hebrews, was part of a polytheistic religion in ancient times. This idea is supported by archaeological and historical evidence, as well as by the biblical text itself.
Archaeological evidence from the ancient Near East suggests that the worship of Yahweh was originally one of many gods worshipped by the Israelites and other Canaanite peoples. For example, inscriptions and other artifacts from the Bronze and Iron Ages (ca. 3000-500 BCE) indicate that the Israelites were familiar with and may have even worshipped other gods such as Baal, El, and Asherah in addition to Yahweh.
Moreover, there are several passages in the Hebrew Bible that suggest that Yahweh was not always the sole God worshipped by the Israelites. For example, in Exodus 12:12, Yahweh declares that he will "execute judgment against all the gods of Egypt." This suggests that the ancient Israelites believed in the existence of other gods alongside Yahweh.
In addition, there are several passages in the Hebrew Bible that suggest that Yahweh was not always considered the supreme God in the ancient Israelite pantheon. For example, in Psalm 82:1, God is depicted as presiding over a council of "gods," suggesting that there were other divine beings in the Israelite religious worldview.
Finally, there is evidence to suggest that the Israelites did not fully embrace monotheism until relatively late in their history. The Hebrew Bible itself contains many passages in which the Israelites are accused of worshipping other gods, suggesting that the transition to monotheism was a gradual process.
Comment: The Hebrew scriptures never hide the fact that at various times the Israelites fell into polytheistic, pagan worship, trying to add to the worship of Yahweh, which they knew Yahweh forbade. At various times, Yahweh caused those idolaters to be taken captive by polytheistic nations. As for Egypt, they'd spent some 400 years surrounded by the polytheism of Egypt but when Yahweh carried out the 10 plagues against Egypt and its gods, to set them free, they knew who the one true God was, and that all the gods of Egypt were false.  That contradicts the idea that they thought them to be real gods.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Comment: While Christians (and modern Jews) and Scripture assert that Yahweh is and always has been the only *real* deity, and while I'm not aware of *Abraham* (or Noah, or Noah's predecessors) ever believing in more than one deity or in any validity to claims that Judaism "came out of" some other, polytheistic religion, it is nevertheless proper to note that Israel has occasionally fallen from that path. +1.
Comment: @Matthew Yes, just because jews fell sometimes into polytheism, this doesn't mean they have a pantheon of tens of gods like Greeks or Egypteans
Comment: @Anne Yes, and because Israel has fallen into sin again, He allowed the babylonians to conquer Israel and they were polytheist, but trough the work of Daniel, God was able to prove Himself as the sole God to the pagan king of Babylon Nebuchadnezzar. And prophet Elijah(which BTW for catholics and orthodoxes is celebrated today, 20th of July) fought polytheism and idolatry against king Ahab.
Answer: Yes. Canaanite polytheistic religion is the precursor to Judaism, as has been shown by Archeology.
The head of the old Canaanite religion were the chief gods "El" and "Baal", who varied between some kind of echo of each other to sworn enemies. When worship of El became exclusive in some regions, worshippers of Baal became hated, and the enemy aspect between them grew. Eventually the followers of El genocided the majority of the followers of Baal.
El was the leader of a council of gods called the "El Oheim" (which literally meant Council of El), and is the origin for god's later name "Eloheim" when the religion turned monotheistic.
We can see the presence of this polytheistic view in Genesis 3:22 where God/El says, "And the LORD God said, 'The man has now become like one of us'". You can also see echos of it in the pre-Noah stories of the Nephillim, which is in some ways an retcon of earlier polytheism.
The journey between its origins to present is as such:
Old Canaanite religion: Polytheistic (El is important, but not exclusively at top)
Canaanite religion: Polytheistic (El is prominent at the top)
Old Judaism: Ethnotheistic (God is the only god of Israel, other culture's pantheons are considered real for them. Gods are intrinsically tied to their cultures.)
The Judaism we're more familiar with: Monotheistic with lesser divine beings (angels)
Old Christinaity: Mostly Judaic monotheistic
Middle Christianity: - This gets really complicated -
Modern Christianity: Trinitarian (3-in-1 pseudo-monotheistic-but-not-quite)
If you want to research further, here's some useful sources:
Wikipedia: Origins_of_Judaism
Wikipedia: History of Israel
Youtube: Esoterica: Who is Yahweh - How a Warrior-Storm God became God of the Israelites and World Monotheism
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Comment: @ lilHar Thanks for listing some resources. However tje summary given in your answer does not accurately reflect the facts of history. E.g. "Trinity doctrines did not begin with Modern Christianity".  And the "followers of El did  not genocide (sic) the worshippers of Baal."  It is recommended that more study of history be done before you submit more answers. Also, study the Bible; it's great for the soul!
Comment: True, trinity actually began in western Roman Paganism wit the worship of the holy family, Mother, Father, and Child. But it's existence in Abrahamic Christianity didn't come about until after Rome adopted Christianity, the beginning of modern Christianity. And yes, the followers of El *did* Genocide the followers of Baal during the Bronze Age Collapse when the Jews were still known as the Habiru. Not only is it historically shown, but the book of Joshua & Judges lays out a mythologized and propagandized version of that exact same genocide.


How can I wipe all files and software not part of Ubuntu?

Question: I have a dev machine that I use npm and node on. I have been having trouble with permissions issues and repeatedly tried uninstalling and working with nvm and other stuff. I'm not really looking for ways to solve that issue and would prefer to start from a clean slate. Is there a way to wipe everything from my system?
Comment: Ubuntu doesn't really have any "factory reset" as far as I know. If you want a fresh system, backup the files you want to keep and reinstall from scratch.
Comment: @Pfap to expand on what ByteCommander said, the best way to accomplish this (and yes, this is preperation that must be done before installing, you would have to think ahead) , is to install /home on a seperate partition. you can then reinstall ubuntu but reusing your current home. some programs do install to home but you can easilly find their folders and delete them (as well as the configuration/preferences files for them and other applications) from your home. having done all this you'd be back at square one. (but having preserved music, videos, pictures and documents.
Comment: When I mess things up, I simply insert the boot DVD and do an " Erase and Install " cleaning. It will give you whatever DVD / USB you put in.
Comment: This question should be deleted as the only answer is to do a fresh install.
Answer: You can find the packages you installed with the terminal command:
<code>comm -23 <(apt-mark showmanual | sort -u) <(gzip -dc /var/log/installer/initial-status.gz | sed -n 's/^Package: //p' | sort -u)
</code>
Removing those should bring you pretty much back to the install as far as packages are concerned.  Of course, this wont fix permissions or remove anything you installed outside the packages system.


History data from IE

Question: Where does Internet Explorer store the history data, i.e. the list of URL that have been visited? I am using Windows XP SP3 and IE7. Basically I would like to read the list of URL and make some statistics on how often what pages are visited.
Answer: Internet Explorer seems to keep its history in hidden directories under C:\Documents and Settings\USERNAME\Local Settings\History\History.IE5.  Note that some directories in this path are also marked hidden or system.  The history's format is opaque, but there's code at CodeProject that can decode the contents.  You can also find a list of typed URLs under HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TypedURLs.
An easier alternative might be to setup an HTTP proxy between the IE and the internet, and then examine the proxy's log.
Answer: The correct way to do this is CoCreate(CLSID_CUrlHistory, IID_IUrlHistoryStg) and call IUrlHistoryStg::EnumUrls().
Answer: It's stored in the registry:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TypedURLs

History data from IE


How much torque does an engine produce when slowing down with no throttle?

Question: If I rev (for example) a small 1.5L 4 cylinder engine up to 4000 rpm in neutral then let off the accelerator (gas) pedal completely, how much torque will the engine produce as it slows down? How long will it produce that torque? For example if had it in gear and immediately let the clutch out while it was slowing down from 4000 rpm, how much engine force would I transfer to the wheels while the engine was slowing down?
Answer: I don't know about modern computer-controlled ignition cars, I guess it depends on their programming, which is adjustable in some cars. some drag racers tamper with the computer.
In the old carburetor cars if you let go of the gas pedal the flow of gas to the carburetor stops and its flap closes. The engine turns into an air pump producing negative torque.
The flow of power reverses, meaning the power from the wheels turns the engine. In diesel trucks, this engine break is used to protect the brakes from overheating.
Comment: diesel engines without the use of a special device ("Jake Bake") have no engine braking because they have no throttle.


How do I check to see if a value is an integer in MySQL?

Question: I see that within MySQL there are Cast() and Convert() functions to create integers from values, but is there any way to check to see if a value is an integer?  Something like is_int() in PHP is what I am looking for.
Comment: so sadly we must create is_int() function in Mysql
Answer: I'll assume you want to check a string value. One nice way is the REGEXP operator, matching the string to a regular expression. Simply do
select field from table where field REGEXP '^-?[0-9]+$';

this is reasonably fast. If your field is numeric, just test for
ceil(field) = field

instead.
Comment: @MatthewCornell, He said if your field is numeric. That's so you can test if a number is an integer. It won't work on strings, that's why the first option is there.
Comment: The 'ceil(field) = field' test is a nice idea, but as @Jumpy pointed out, it fails on non-numeric data: SELECT ceil('four') = 'four'; -> 1
Comment: If the data might include whitespace, this would fail. Consider testing trim(field), possibly with an extra arg to remove newlines.
Comment: the the data is numeric, may do this too: select ((field % 1) = 0);
Comment: Thanks, but for the numeric comparison, I think you need not(strcmp(ceil(field),field))
Answer: Match it against a regular expression.
c.f. http://forums.mysql.com/read.php?60,1907,38488#msg-38488 as quoted below:

Re: IsNumeric() clause in MySQL??
Posted by: kevinclark ()
Date: August 08, 2005 01:01PM
I agree. Here is a function I created for MySQL 5:

CREATE FUNCTION IsNumeric (sIn varchar(1024)) RETURNS tinyint
RETURN sIn REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';

This allows for an optional plus/minus sign at the beginning, one optional decimal point, and the rest numeric digits.
Comment: Thanks, your solution takes care of decimals also
Answer: Suppose we have column with alphanumeric field having entries like
a41q
1458
xwe8
1475
asde
9582
.
.
.
.
.
qe84

and you want highest numeric value from this db column (in this case it is 9582) then this query will help you
SELECT Max(column_name) from table_name where column_name REGEXP '^[0-9]+$'

Comment: *'10000'* is higher, but your query would still return *'9582'*.
Answer: Here is the simple solution for it
assuming the data type is varchar
select * from calender where year > 0

It will return true if the year is numeric else false
Comment: In a varchar, this will also return true if the first character is numeric.
Comment: Didn't notice that. up-voting your comment :)
Answer: This also works:
CAST( coulmn_value AS UNSIGNED ) // will return 0 if not numeric string.

for example
SELECT CAST('a123' AS UNSIGNED) // returns 0
SELECT CAST('123' AS UNSIGNED) // returns 123 i.e. > 0

Comment: what about `SELECT CAST('12a34' AS UNSIGNED)`, which returns `12`?
Comment: This works perfect if you need to test for non-numeric items, this deserves more +1s. The other answers are harder to reverse the test to find the non-numeric items.
Comment: @DrCord this does not work for the case Mike C described, hence is very unreliable
Comment: This does not work if we have INTEGER VALUE = 0.
`SELECT CAST( 'empty' AS UNSIGNED ); /*return 0*/`

`SELECT CAST( 1 AS UNSIGNED ); /*return 1*/`
`SELECT CAST( 0 AS UNSIGNED ); /*return 0*/`
```
Answer: To check if a value is Int in Mysql, we can use the following query.
This query will give the rows with Int values
SELECT col1 FROM table WHERE concat('',col * 1) = col;

Comment: This will also select non-integer numbers (eg. *'3.5'*).
Answer: The best i could think of a variable is a int Is a combination with MySQL's functions CAST() and LENGTH().
This method will work on strings, integers, doubles/floats datatypes.
SELECT (LENGTH(CAST(<data> AS UNSIGNED))) = (LENGTH(<data>)) AS is_int

see demo http://sqlfiddle.com/#!9/ff40cd/44

it will fail if the column has a single character value. if column has
  a value 'A' then Cast('A' as UNSIGNED) will evaluate to 0 and
  LENGTH(0) will be 1. so LENGTH(Cast('A' as UNSIGNED))=LENGTH(0) will
  evaluate to 1=1 => 1

True Waqas Malik totally fogotten to test that case. the patch is.
SELECT <data>, (LENGTH(CAST(<data> AS UNSIGNED))) = CASE WHEN CAST(<data> AS UNSIGNED) = 0 THEN CAST(<data> AS UNSIGNED) ELSE (LENGTH(<data>)) END AS is_int;

Results
**Query #1**

    SELECT 1, (LENGTH(CAST(1 AS UNSIGNED))) = CASE WHEN CAST(1 AS UNSIGNED) = 0 THEN CAST(1 AS UNSIGNED) ELSE (LENGTH(1)) END AS is_int;

| 1   | is_int |
| --- | ------ |
| 1   | 1      |

---
**Query #2**

    SELECT 1.1, (LENGTH(CAST(1 AS UNSIGNED))) = CASE WHEN CAST(1.1 AS UNSIGNED) = 0 THEN CAST(1.1 AS UNSIGNED) ELSE (LENGTH(1.1)) END AS is_int;

| 1.1 | is_int |
| --- | ------ |
| 1.1 | 0      |

---
**Query #3**

    SELECT "1", (LENGTH(CAST("1" AS UNSIGNED))) = CASE WHEN CAST("1" AS UNSIGNED) = 0 THEN CAST("1" AS UNSIGNED) ELSE (LENGTH("1")) END AS is_int;

| 1   | is_int |
| --- | ------ |
| 1   | 1      |

---
**Query #4**

    SELECT "1.1", (LENGTH(CAST("1.1" AS UNSIGNED))) = CASE WHEN CAST("1.1" AS UNSIGNED) = 0 THEN CAST("1.1" AS UNSIGNED) ELSE (LENGTH("1.1")) END AS is_int;

| 1.1 | is_int |
| --- | ------ |
| 1.1 | 0      |

---
**Query #5**

    SELECT "1a", (LENGTH(CAST("1.1" AS UNSIGNED))) = CASE WHEN CAST("1a" AS UNSIGNED) = 0 THEN CAST("1a" AS UNSIGNED) ELSE (LENGTH("1a")) END AS is_int;

| 1a  | is_int |
| --- | ------ |
| 1a  | 0      |

---
**Query #6**

    SELECT "1.1a", (LENGTH(CAST("1.1a" AS UNSIGNED))) = CASE WHEN CAST("1.1a" AS UNSIGNED) = 0 THEN CAST("1.1a" AS UNSIGNED) ELSE (LENGTH("1.1a")) END AS is_int;

| 1.1a | is_int |
| ---- | ------ |
| 1.1a | 0      |

---
**Query #7**

    SELECT "a1", (LENGTH(CAST("1.1a" AS UNSIGNED))) = CASE WHEN CAST("a1" AS UNSIGNED) = 0 THEN CAST("a1" AS UNSIGNED) ELSE (LENGTH("a1")) END AS is_int;

| a1  | is_int |
| --- | ------ |
| a1  | 0      |

---
**Query #8**

    SELECT "a1.1", (LENGTH(CAST("a1.1" AS UNSIGNED))) = CASE WHEN CAST("a1.1" AS UNSIGNED) = 0 THEN CAST("a1.1" AS UNSIGNED) ELSE (LENGTH("a1.1")) END AS is_int;

| a1.1 | is_int |
| ---- | ------ |
| a1.1 | 0      |

---
**Query #9**

    SELECT "a", (LENGTH(CAST("a" AS UNSIGNED))) = CASE WHEN CAST("a" AS UNSIGNED) = 0 THEN CAST("a" AS UNSIGNED) ELSE (LENGTH("a")) END AS is_int;

| a   | is_int |
| --- | ------ |
| a   | 0      |

see demo
Comment: it will fail if the column has a single character value. if column has a value 'A' then Cast('A' as UNSIGNED) will evaluate to 0 and LENGTH(0) will be 1. so LENGTH(Cast('A' as UNSIGNED))=LENGTH(0) will evaluate to 1=1 => 1
Comment: Thanks for the comment that case was indeed untested @WaqasMalik working and testing a patch right now.. something like `SELECT "a", (LENGTH(CAST("a" AS UNSIGNED))) = CASE WHEN CAST("a" AS UNSIGNED) = 0 THEN CAST("a" AS UNSIGNED) ELSE (LENGTH("a")) END AS is_int;`
Comment: This is such a cool solution. I think it fails for negative integers, does it change anything substantive (in edge cases) to switch your solution to signed integers? I've been testing using your fiddle as the base. `set @val = '1.';
SELECT @val, LENGTH(CAST(@val AS SIGNED)) = IF(CAST(@val AS SIGNED) = 0, CAST(@val AS SIGNED), LENGTH(@val)) AS is_int;` This refactoring handles all above cases, but even my adjustment doesn't handle -1.0 or '-1.' Again, a super cool solution.
Comment: thanks for the positive and kind words @spen.smith not tested fully but try with ABS() -> https://www.db-fiddle.com/f/NNXJ9cPwxjNPz9NknsSGU/3
Answer: What about:
WHERE table.field = "0" or CAST(table.field as SIGNED) != 0

to test for numeric and the corrolary:
WHERE table.field != "0" and CAST(table.field as SIGNED) = 0

Comment: CAST(table.field) != 0 will not work as it needs a type to cast.
Comment: @Tom Auger: Another answer covered the regex type solutions. What I meant by "7x is considered a number" is that this statement is true: select 7 = '7q'
Comment: This works perfect if you need to test for non-numeric items, this deserves more +1s. The other answers are harder to reverse the test to find the non-numeric items.
Comment: This doesn't work for numbers like "0000", " 0" (space) and "7x" (which is considered a number).
Comment: @MichaelGrazebrook I suppose you could do a regexp for the first two cases. "7x" is considered a number? "0x7" is a number, but 7x?
Answer: I have tried using the regular expressions listed above, but they do not work for the following:
SELECT '12 INCHES' REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$' FROM ...

The above will return 1 (TRUE), meaning the test of the string '12 INCHES' against the regular expression above, returns TRUE.  It looks like a number based on the regular expression used above.  In this case, because the 12 is at the beginning of the string, the regular expression interprets it as a number.
The following will return the right value (i.e. 0) because the string starts with characters instead of digits
SELECT 'TOP 10' REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$' FROM ...

The above will return 0 (FALSE) because the beginning of the string is text and not numeric.
However, if you are dealing with strings that have a mix of numbers and letters that begin with a number, you will not get the results you want.  REGEXP will interpret the string as a valid number when in fact it is not.
Comment: This is incorrect. Did you test it? When I run your first example, it returns `FALSE`, as expected, because the regex ends with `$` which means the end of the string, so it is checking for only numbers, as intended by the author.
Answer: This works well for VARCHAR where it begins with a number or not..
WHERE concat('',fieldname * 1) != fieldname

may have restrictions when you get to the larger NNNNE+- numbers
Comment: This doesn't seem to work for single char strings `set @val = '5';
SELECT @val, concat('', @val * 1) != @val is_int;`
Answer: for me the only thing that works is:
CREATE FUNCTION IsNumeric (SIN VARCHAR(1024)) RETURNS TINYINT
RETURN SIN REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';

from kevinclark all other return useless stuff for me in case of 234jk456 or 12 inches
Answer: someone above says to test using ceil(@my_num) = @my_num.
This does not quite do the trick, however. Notice that ceil(2.7) does equal 3:
select ceil(3) = 3 as test1, ceil(3.2) = 3 as test_2, ceil(2.7) = 3 as test_3;
If you are trying to determine if a variable is an int, this test does not give you enough information.


What should I do as a player to prepare for a gaming convention?

Question: Should I bring lots of gaming books? Do I really need to sleep while I'm there? Trail mix is OK food, right?
Comment: This could really use more content than just rhetorical questions.
Comment: Possibly some of these questions are rhetorical or I already know the answers, but I think this one will come up a lot so I wanted to get it in place.
Comment: It sounds like you mean as a player, but it doesn't hurt to ask - are you attending as a GM as well?
Comment: Oh, very good question. Let me edit to make it more specific; I meant as a player.
Answer: I will give you advice in terms of my 2009 visit to Gencon.
Is this a large convention?  You will want a good pair of shoes with a fair amount of tread on them.  You may want to consider getting some new insoles if a lot of walking will be involved for more than a day.
Invest in a backpack that allows you to insert a water reservoir or get a good water bottle that is not too troublesome to carry.  Regardless, get a sturdy, comfortable backpack to hold your gaming materials and purchases.
Larger conventions can be loud and busy.  Be sure to give yourself a break a few times a day for at least 15 minutes.  Get a snack, sit on a bench, or just take a breather.
Organize in advance with your travel companions!  Do not wait until you are at the convention to decide what events you want to do.  Work out any shared hotel arrangements at LEAST two weeks before the convention.  Know when everyone intends to arrive and leave so nobody gets stranded.  If you are capable of securing your own room, do so.  You will not regret it and enjoy the comfort, peace, and quiet.
Did you pick out some events?  Get there ten minutes early.  If it's a high demand event, get there half an hour early (True Dungeon, panel w/ Monte Cook, etc).
Carry a light snack or two in your pack.  Consider the dining options in town.  Things closer to the convention area will be more expensive with long wait times.
Try something new!  Pick out an event or two from a game you've never heard of that sounds interesting.  Many games are being presented by members of the company behind the game and in some cases the game designer themselves.
Be prepared to spend $100 more than you planned on in the dealers area.  There are shiny things you did not know even existed in here and you will want them.
Bring a camera.  You'll see people in costume, amazing artwork, and/or oddities you will want to remember.
Have fun!
Answer: I'd add "bring some cash."  Many vendors aren't set up for credit/debit cards and are reluctant to accept checks from someone who may live 1,000 miles away.  There will be things you want to buy.  I don't buy much in the way of gaming product, and there are always things I want to buy.
Answer: Create a packing checklist well in advance of the con. Add to it as needed. Otherwise, you WILL forget stuff.
Before you go, do some websearching to figure out where you can eat near the con. Don't leave this till you get there. You might not have internet or whatever. Print a local street map. You might also want to know where the local FedEx or other copy center is.
If you have lots of friends and a smartphone that can do Twitter, set up a twitter hashtag for coordination with your friends: "i'm running dnd at embassy suites at 9 #genconfools"
Four hours of sleep is for young kids, and you're no spring chicken. Get seven. Don't overschedule yourself and you'll enjoy the events you attend far more than you will if you're exhausted.
At GenCon or some other big con, leave at least one whole event slot wide open. You'll want to spend some time browsing the goodies in the exhibit hall. Check out everything the con has to offer: the art show, the wargaming, boardgaming, computer games, card games, and so on. Even if you don't participate, just seeing this stuff is cool (wargame dioramas RULE).
Answer:
I used to bring a lot of gaming books, but I found that — most of the time — all it did was add weight to my bag. If the game you're playing is complex, or you have a character of your own that you're taking and you know you'll need detailed rules, bring those books. Otherwise, bring dice and pencils and rely on the pre-gen character sheet and the DM to help you out.
The rule is 4-2-1: at least four hours of sleep, two meals (or two hours and four meals) and one shower every day.
It can be, but I'd recommend something with a little protein in it as well. The big deal is water; stay hydrated and you'll go longer. (Caffeine is great, and I'm a big fan, but it'll keep you going to the bathroom and empty you out. Plus, convention centers and hotels can be dry.)


What is the most powerful spell?

Question: What is the most powerful spell in Wizard101?
My friend says it is Heck Hound with damage over time with power pips.
But is the spell storm owl or tempest?
I really want to know!
I did search it up.... but I also need to know if damage over time counts in this category?
Comment: Bosspvz2, your question is unclear.  Are you asking which spell in the game averages the highest damage over time, or are you meaning "powerful" in a different sense?
Comment: What I mean is would most powerful mean including spells which do damage over time or excluding them. Thanks for asking, if you just want more clarification, then ask me again. Thanks! :)
Answer: Looking at the wording available for the Heck Hound spell:

Deals 130 Fire Damage per Pip over 3 Rounds (accuracy 75%)

It can be seen that the damage this spell can give is dependent on how many rounds you manage to stay fighting, as 1 more Pip is added for every round you stay fighting.
Thus, the only way to compare this spell in regards to damage is by comparing it to other spells that use the same number of Pips.
So, for the number of pips, this is the total average (Damage * Pips * Accuracy * 3 rounds) damage done by Heck Hound:
<code>1   -   292.5
2   -   585
3   -   877.5
4   -   1170
5   -   1462.5
6   -   1755
7   -   2047.5
8   -   2340
9   -   2632.5
10  -   2925
</code>
We can see here that the spell's damage is quite high. Let's also assume that there is only one enemy, so that spells that target all enemies can be considered fairly.
Running down all math, I was able to produce an Excel file detailing all spells' damage. By analyzing the data one can check that Heck Hound is indeed the most powerful (in terms of damage) spell, except for the 8 Pips case, where King Artorius (Myth) alone gains a small advantage.
The Judgement spell from the Balance School has similar mechanics to this spell, but falls a lot short, due to the round bonus.
Answer: If multiple I would say Call of Kuruhulu with colossal. It gives you 1k base damage. With blades against 4 people yout get health back instantly while crippling all. Alone I would probably say Judgement.
Comment: Welcome to Arqade! Please clarify your answer. It is difficult to understand right now.

What is the most powerful spell?


Opening jpegs on Android - I get an OutOfMemoryException

Question: In my application I need to process images taken by Android's built-in applications. They're saved into JPEG format, and I need to get access to each pixel. I tried to create a Bitmap instance from the jpeg image, but very often I get an OutOfMemoryException. I can't resize or crop image. Does a solution exist?
Comment: Can you explain the use case, what do you need to do with the images? Maybe there are alternative ways of doing it.
Comment: I need to execute various Digital Image Processing algorithms, such as Binarization, convert to grey-scale, different filters etc.
Answer: BitmapFactory will often throw OutOfMemoryExceptions and I'm afraid that I've never really discovered any workarounds.  It seems to be doing its own memory management, and sometimes it really isn't capable of parsing an image.  In a couple of applications I've worked on that had to deal with images heavily, I just had to catch the exception and then leave blank spots in the UI when I couldn't get an image parsed.  Sometimes, if you try again later, those images will parse, presumably when the internal memory state of BitmapFactory is working better.
When I was working on a J2ME application, I tried to find a pure Java open source JPEG parser so I could use it on phones that didn't have built-in JPEG support.  Turns out that such a thing is difficult to find, and the closest I could find was buried in the depths of the Eclipse source.  I was able to take that source, de-Eclipsify it and try it out.  It did have the virtue of reading in things line by line (although I'm not sure how it would have done with progressive scan JPEGs), but it was ridiculously slow on our J2ME devices (particularly since they were mostly the lower end ones) so we didn't end up using it for anything.
Answer: Check out BitmapRegionDecoder. It is available since API level 10.  You can decode parts of an image file and process each chunk.


Can't connect to a computer that I can ping

Question: I have two devices.  One is a Raspberry Pi and the other a full Linux computer from my school.  I am trying to establish a TCP socket connection between the two.  I can already do this between the Pi and another Pi, and likewise between the Linux box and another such box also belonging to the school.  What I cannot do is connect() between the Pi and the Linux box.  I can ping each from either, though, so I have reason to believe they are on the same network.  My guess is that there is a firewall blocking the Pi from connecting, but is there a better explanation?  How can I get the things talking?
Comment: you have a 10/100 or 10/100/1000 switch in between or trying to direct connect them?
Comment: Firewall sounds like the most likely explanation.
Comment: Yes, firewall is likely, but another possibility is NAT between them, and you have tested pinging the client from the server, but not the server from the client.
Answer: There are many possibilities. First, you should gather more diagnostic information.
Try traceroute -n <ip> to see the intermediate hosts. They could indeed be in a different local network with a filtering router between them.
Try connecting to the peer with telnet <ip> <port>. If it says Connection refused, it is likely that the other host is reachable, but there is nothing listening on the port. If there is no response (packet is dropped), it is likely a filter blocking the connection.
Next, try nmap <ip>. This will tell you which ports are open and blocked.
Examine IP filter rules:
iptables -L INPUT

on both hosts. You can remove all (input) rules with iptables -F INPUT. Make sure the default policy is accept iptables -P INPUT ACCEPT.
You could potentially be connecting to a different host entirely if it is a local address (most often 192.168.x.x or 10.x.x.x), and they are separated by a NAT. You could try blocking ping on the remote host temporarily to see if it has any effect:
sysctl -w net.ipv4.icmp_echo_ignore_all=1

It should no longer be possible to ping the remote host. Note: Afterwards, re-enable ping with sysctl -w net.ipv4.icmp_echo_ignore_all=0
Try a different TCP listening server, e.g. python's SimpleHTTPServer:
host1$ python -m SimpleHTTPServer
host2$ telnet <ip> 8000

Comment: I'm out for the weekend now, but I look forward to trying it out.  Many thanks.  I'll go ahead and select this as an answer because I wanted a place to look and this is it.
Comment: This helped a lot. I have a remote Windows PC that was responding to ping but not ssh, which I use for games mostly and because my linux box Ubuntu distro is so old it can't be updated any more. I remoted into my linux box, ran nmap on the Windows machine, and found out that the vnc port was open. I vnc'd into my linux box, and then vnc'd into the Windows box to find it had rebooted without asking (grr) and was at the initial login prompt. From there I could login to Windows and start WSL which was providing my ssh server. This post was the key!
Answer: I was facing a similar problem.
On browser, it shows "This site can't be reached. x.x.x.x refused to connect. ERR_CONNECTION_REFUSED".
But on the terminal, I was able to ping the IP_Address.
One of the possible problems can be because of the firewall.
Try to run these commands on the x.x.x.x machine terminal.
sudo firewall-cmd -state
systemctl stop firewalld

this will stop the firewall and now you can reload the browser URL. It will work if firewall was blocking access.
If this doesn't work, you can surely refer to another answer. I also tried it but got stuck at nmap command. "nmap - RTTVAR has grown to over 2.3 seconds, decreasing to 2.0"
Comment: Wow, taking me back to my senior design project... Pretty sure this already got resolved, and I graduated anyway :P but thanks for the response!


How to conduct the electron double slit experiment

Question: I am planning to conduct the electron double slit experiment for a project in my school. Even after researching quite a bit online, I wasn't able to find a proper guide that explains the materials and procedure involved in carrying out the experiment. How do I go about conducting it and what do I need for it?
Comment: What resources do you have?  A monoenergetic electron beam source would be a good start.
Comment: The electron diffraction in general is done in schools with a purpose built apparatus. It is a CRT with electrostatic deflection that allows the beam to be steered to different slits and grids in a plate between the gun and the screen. I can't recall ever seeing any electron double slit apparatus.
Comment: If you're not buying a commercial off the shelf system such as @C.Towne describes, a high quality vacuum system and some practice using it would *also* be a good start. And some kind of position sensitive electron detector with a suitable resolution (quite a bit higher than typical textbook figures would lead you to believe if you mistake them for being to-scale).
Answer: I do not think that you have thought through what you are planning to do.
You may have at school an apparatus with which electron diffraction can be demonstrated.
It consists of electron gun probably with a maximum voltage of $\rm 5000\, V$ which fires a stream of electrons at at very thin graphite target.
The electrons then hit a fluorescent screen which emits light when electrons hit it.
The whole apparatus is encased in a glass envelope inside which the is a very low pressure (vacuum).
The vacuum is there so that the electrons can pass between the various parts of the apparatus unhindered by collision with air molecules.
The wavelength of the electrons emitted by such an electron gun is about $1.7 \times 10^{-11}\,\rm m$ and the spacing between the atoms in the very thin graphite sample, which has to be of the same order of magnitude as that of the electrons to get an easily detectable effect, is approximately $1 \times 10^{-10}\,\rm m$.
If the accelerating voltage is decreased then the wavelength of the electrons increases but the brightness of the pattern seen on the fluorescent screen decreases so that below about $1000\,\rm V$ not pattern can be seen on the screen.
So will need an electron gun, a double slit and a means of detection of the electrons with the whole apparatus enclosed in an evacuated chamber.
If you plan to use a fluorescent screen then your slits need to be fairly close together ($\approx 10^{-10}\,\rm m$) and also of small width.
Similar experiments have been done using an apparatus based on an electron microscope and instead of two slits the equivalent of a a Fresnel biprism was used.
Here is one article about such an experiment.
I think that you have chosen an experiment which would be rather hard to do in a school laboratory?


Duplicate instances not removed from queryset

Question: I'm coming across a problem with the queryset returned in the get_tag_posts method within the Profile model. With the query as it is written, it won't remove duplicates even though .distinct() is being invoked.
To provide a brief illustration of the problem:

Question 1 - Tag A
Question 2 - Tag A
Question 3 - Tag A, Tag B

As get_tag_posts is invoked it includes the following queryset:
<QuerySet [<Tag: A>, <Tag: A>, <Tag: A>, <Tag: B>]>
Yet I'm expecting the queryset to be returned as: <QuerySet [<Tag: A>, <Tag: B>]>
From there each instance is annotated to calculate the number of times a given tag has been posted by a user. Why are duplicates of a single instance not being removed in this case?
class Profile(Model):
    user = OneToOneField(settings.AUTH_USER_MODEL, on_delete=CASCADE)

    def get_tag_posts(self, order_by=None):
        if not order_by:
            order_by = "-question__date"
        elif order_by == "name":
            pass
        else:
            order_by = "-score"

        questions_with_tag = Subquery(self.questions.filter(
            tags__name=OuterRef("name")).only('id'))
        tags = Tag.objects.filter(
            question__profile=self
        ).distinct().order_by(order_by)
        return {
            'records': tags.annotate(times_posted=Count(questions_with_tag)),
            'title': f"{tags.count()} Tags"
        }

class Tag(Model):

    name = CharField(unique=True, max_length=25)

class Post(Model):

    body = TextField()
    date = DateTimeField(default=timezone.now)
    comment = ForeignKey('Comment', on_delete=CASCADE, null=True)
    profile = ForeignKey(
        'authors.Profile', on_delete=SET_NULL, null=True,
        related_name='%(class)ss',
        related_query_name="%(class)s"
    )
    vote = GenericRelation(
        'Vote', related_query_name="%(class)s"
    )
    score = IntegerField(default=0)

class Question(Post):

    title = CharField(
        max_length=80, unique_for_date="date",
        help_text="Concisely state the problem you're having",
        error_messages={
            "max_length": "The title of your question is too long"
        }
    )
    tags = ManyToManyField(
        'Tag', related_name="questions", related_query_name="question"
    )
    views = IntegerField(default=0)
    visible = BooleanField(default=True)
    objects = Manager()
    postings = QuestionSearchManager()
    searches = QueryStringSearchManager()

Comment: What is `question__profile=self` supposed to be doing?  The `Tag` model doesn't have any foreign keys.
Comment: I was using a reverse relationship with what you're referring to:

https://stackoverflow.com/a/43133136/11611632
Answer: Many to Many Relations actually includes 3 tables. In your Example: Questions, Tags, Question_Tag_Relations
Question_Tag_Relations

PK
Question_PK
Tag_PK

1
1
1

2
2
1

3
3
1

4
3
2

When you grab distinct() you are grabbing Distinct PKs in this relation table, not the tags themselves.
So you need to get the tag_pk (idk the specific column name)
Some DBs support distinct by column, like: ~.distinct('tag_pk')
But if your DB doesn't support that you might have to go the: ~.values_list('tags').distinct() route.. I believe this is an extra query tho
This would be my guess:     Tags.objects.filter(pk__in=self.questions.values_list('tags').distinct())


Are updates available for Maps on the iPhone 6s plus

Question: Maps for my area has not been updated and is missing some major highway additions.  I'm currently using Google as a substitute but its not as integrated into iOS.
Answer: Apple does do updates but they're primarily server-side, so you might not notice the updates each time.
The best way to send Apple feedback about incorrect Maps data is to use Report a Problem under the ⓘ button.  There you can indicate what error the map has and send it to Apple.  Unfortunately, Apple has not published or otherwise indicated a timeframe as to when they will push-out corrections.


How to make ChildWindow blocking

Question: The ChildWindow is a modal window, but it does not block. Is there any way to make it blocking? I basically want a ShowDialog() method that will call ChildWindow.Show() but then not return until the user has closed the ChildWindow. I tried using Monitor.Enter() to block after ChildWindow.Show(), but the ChildWindow never rendered and the browser just hung. Anyone have any ideas?
Comment: Could you explain what are you trying to achieve?
Comment: Just a simple modal blocking window similar to MessageBox.Show() or Form.ShowDialog()
Comment: I've tried everything and I never found a solution. I was trying to make my own MessageBox. I even tried async but it always locked up. I gave up after reading that Tim Heuer saying it wasn't possible to have true Modal.
Answer: I don't believe it supports that behavior. You can vote for it on CodePlex. Depending on what you want, you might either look at some of Tim Heuer's workarounds here, or use a different custom control, like the Silverlight Modal Control (on CodePlex).
Answer: You can't do what you are trying to do in Silverlight. Any changes you make to the UI will run on the UI thread. If you block the UI thread, the user can't interact with the browser, so there is no action that they could take to unblock the thread.
If you really want to create a blocking dialog window, the only way to do that is from a non-UI-thread. E.g. you could create a method that looks something like:
    private void ShowModalDialog()
    {
        AutoResetEvent waitHandle = new AutoResetEvent(false);
        Dispatcher.BeginInvoke(() =>
        {
            ChildWindow cw = new ChildWindow();
            cw.Content = "Modal Dialog";
            cw.Closed += (s, e) => waitHandle.Set();
            cw.Show();
        });
        waitHandle.WaitOne();
    }

This method will show a dialog window and won't return until the dialog window is closed. But this method can only be called from a non-UI-thread. Calling it from the UI-thread will cause a deadlock (since the UI-thread is waiting for an event that can only fire on the UI-thread).
Alternatively, you should consider making your logic async rather than forcing it to be synchronous.
Comment: I like this solution and it looks like it should work, but since it can't be called on the UI thread, I'm not sure I can use this (even though I didn't actually specify that in my question (since I didn't even think about it then)). Either way, great workaround.
Answer: If you want to perform some action on your child window close, use the following code. Hide unwanted controls before invoke and show on close of the child window, simple :)
ChildWindow cw = new ChildWindow();
cw.Closed += new EventHandler(cw_Closed);
cw.Show();

Answer: You could try to always cancel the close event and set the DialogResult later.
void ConfigTemplatePopup_Closing(object sender, System.ComponentModel.CancelEventArgs e)
    {
        if (tmpDialogResult != null || DialogResult == true) return;
        tmpDialogResult = DialogResult; //this is a field
        e.Cancel = true;
        var myMessageBox = new WspMessageBox("Are you sure you want to close?", true);
        myMessageBox.Closed += (s, e2) =>
                                    {
                                        if (wspMessageBox.DialogResult == true)
                                        {
                                            DialogResult = tmpDialogResult;
                                        }else
                                        {
                                            tmpDialogResult = null;
                                        }
                                    };
        myMessageBox.Show();
    }

Answer: Using async and await in Silverlight 5 you can easy create a static Show method that can be  blocking, like
public partial class MyDialog {
  MyResultType result;
  readonly AutoResetEvent waitHandle;

  MyDialog() {
    InitializeComponent();
    waitHandle = new AutoResetEvent(false);
  }

  public static Task<MyResultType> Show() {
    var dialog = new MyDialog();
    dialog.Show();
    dialog.Closed += (s, e) => dialog.waitHandle.Set();
    return Task<MyResultType>.Factory.StartNew(() => {
      dialog.waitHandle.WaitOne(); return dialog.result; });
  }

  void OkButton_Click(object sender, RoutedEventArgs e) {
      result = new MyResultType();
      // Initialize result...

      Close();
  }
}

and call the dialog like
public async void TestDialog() {
  var result = await ConfirmBox.Show();

  // This code will be performed after the Dialog is closed.
  // use result...
}

Comment: -1 I'm afraid, because this snippet doesn't compile.  The output of `Task.Factory.StartNew()` is not awaitable.  Also, while this answer introduces the async/await pattern into the mix, it does not solve the fundamental problem that you can't block the UI thread without freezing the browser, so this approach offers no real value over and above Keith Mahoney's solution.
Comment: This snippet is from my working project. I use it as a common solution for dialogs. To compile it you'll need the "async targeting pack", which you can add to your project using the nuget.  Please read the article using the link in my answer.
Answer: I hacked away at creating a "blocking" modal dialog, by having a custom control that has a vertical- and horizontal alignment as stretch, and then add that as a child of the layout of the current control.
e.g.
   <Grid x:Name="LayoutRoot" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
        <Rectangle Fill="LightBlue" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Opacity="0.3" />
    </Grid>

and then in the custom control
Utilities.UITools.MessageBox x = new Utilities.UITools.MessageBox();
x.SetError(e.Result);
this.LayoutRoot.Children.Add(x);

Depending on what has to be displayed in the modal, I dynamically add controls to the modal layout. Clearly, not an elegant solution, but at least it works.
Comment: That would make it modal in a way, but it doesn't appear that it would be blocking in that there is no function call that would block until the user closed the message box.
Comment: I made it blocking by linking an event into the message box.  Thus, it blocks the rest of the program until the event fires

How to make ChildWindow blocking


How come gravity generates enough pressure to start a fusion reaction in stars even though it is the weakest force?

Question: Given the fact that gravity is the weakest of all forces, how does a gas cloud manage to collapse on itself under gravity and start a fusion reaction, outweighing the electromagnetic and nuclear forces between atoms? Even if the mass is greater, it would mean that the electromagnetic and nuclear forces between atoms would also be greater. How does gravity overcome these forces?
Answer: The unique thing about gravity is that it is always attractive. Your intuition would be correct if the gas cloud was made purely of electrons, for example, as then the electromagnetic repulsion would be much greater than the gravitational attraction. But because there are both positive and negative charges in the gas cloud, the electromagnetic forces cancel out over long distances. Eventually the gas cloud can accumulate so much mass that it can overcome the other forces, despite gravity's relative weakness at the inter-particle level.
Comment: _"the electromagnetic forces cancel out over long distances"_ -- what role is played by the fact that gravity acts over longer distances (i.e. weakens less quickly) than the stronger forces? Am I even right in thinking that's the case?
Comment: @PeterDuniho:  Both electromagnetic forces and gravitational forces are effectively infinite range.  More precisely, they're both inversely proportional to the square of the distance between the objects.  In contrast, the strong & weak nuclear forces are (roughly speaking) proportional to $e^{-r/\lambda}/r^2$, where $\lambda$ is a length on the scale of nuclei;  this exponential factor means that the forces fall off much more quickly than for the "long-range" forces of electromagnetism & gravity.
Comment: I have to say - gravity is not always attractive. The acceleration of the universe shows that. i.e. in units of the critical density, present density of matter + dark energy - pressure dark energy = -1 (more or less). Since there is a minus sign in front of the whole thing, the acceleration of the universe is positive. This is all gravity, it is just that some terms take the opposite side.


If I have only a king left and two blocked pawns, how many moves does my opponent have to mate?

Question: I have only king left with two pawns but they are blocked. By how many moves an opponent has to checkmate me?
Comment: Possible duplicate of [With only a king left, how many moves remaining until a draw?](https://chess.stackexchange.com/questions/2500/with-only-a-king-left-how-many-moves-remaining-until-a-draw)
Answer: There is no such limit. In the official rules, §9.3, it is stated that there's a limit of 50 moves during which a pawn must move or a piece/pawn must be captured. If that doesn't happen, you can claim a draw.
I have heard that there are some circles a stronger limit is imposed when the weaker side has only a lone king (so, not two pawns), but those are unofficial rules and we can't say much about that.


Reading order of "A Song of Ice and Fire"

Question: I've become hooked on HBO's A Game of Thrones, so I was going to read the books. However, I'm a little confused as to which order to read them since there are novellas based on chapters of the novels.
This is what I've found online:

Blood of the Dragon (July 1996), taken from the Daenerys chapters in A Game of Thrones.
Path of the Dragon (December 2000), taken from the Daenerys chapters in A Storm of Swords.
Arms of the Kraken (March 2003), based on the Iron Islands chapters from A Feast for Crows.

Should I read the novel first, then the novella for that book, then back to the original series?
Answer: Those novellas are just standalone versions of the book chapters. So don't read them at all.
This does not however cover the novellas in the
Tales of Dunk and Egg series, which are (to date):

The Hedge Knight (First published in the anthology Legends in 1998)
The Sworn Sword (First published in the anthology Legends II in
2003)
The Mystery Knight (First published in the anthology Warriors in
2010)

They are not absolutely required reading, but as they are set in the time before the main novels they do offer a very in depth glimpse into the history leading to the events of the main novels, even if the names of the two main characters sound silly. It specifically gives you a good understanding of the history of the royal Targaryen family, whom we only get glimpses of in the main series since they are all but extinct. The first two have also been released in graphic novel form. All three novellas were published together in a collection called A Knight of the Seven Kingdoms in October 2015.
A second series of novellas have also been written that predate the Dunk and Egg stories. They cover major events in the Targaryen dynasty and are written as scholarly works on the history of those events. To date they are:

The Princess and the Queen (First published in the anthology Dangerous Women in 2013)
The Rogue Prince (First published in the anthology Rogues in 2014)

Note: chronologically, 'The Rogue Prince' happens before 'The Princess and the Queen'.

You can read them either before the main novels (chronological order):

The Rogue Prince (2014)
The Princess and the Queen (2013)
The Hedge Knight (1998)
The Sworn Sword (2003)
The Mystery Knight (2010)
A Game of Thrones (1996)
A Clash of Kings (1999)
A Storm of Swords (2000)
A Feast for Crows (2005)
A Dance with Dragons (2011)

Or you can just read the whole series in publication order, which is (to date):

A Game of Thrones (1996)
The Hedge Knight (1998)
A Clash of Kings (1999)
A Storm of Swords (2000)
The Sworn Sword (2003)
A Feast for Crows (2005)
The Mystery Knight (2010)
A Dance with Dragons (2011)
The Princess and the Queen (2013)
The Rogue Prince (2014)

Once you are done with this, you may want to check into George R R Martin's official site, where he (from time to time) releases teaser chapters from the upcoming book The Winds of Winter.
Related question: When will the A Song of Ice and Fire series be completed? Also, the Wikipedia page on the series stays up to date with official announcements on publications.
There are so far 2 more books slated for the series, but it may yet balloon out to more. They are:

The Winds of Winter (no date yet)
A Dream of Spring (no date yet)
Comment: This is a great answer and I just wanted to add that you can read the chapters of the last two books (4 & 5) chronologically if you want, using the reading order from this question: http://scifi.stackexchange.com/q/45251/5798
Comment: @RoyalFlush - Hmmm. After that thing with his editor claiming 8 books and GRRM denying it (sorta), I'm going to go into denial mode and wait for a more official word on this.
Comment: @VincentSavard - Yeah you're right. I was just waiting until I've read it first LOL. But I guess it won't hurt to include it in the post.
Comment: Hey System, great answer. Maybe you would consider adding TWOIAF to the list, for sake of completion?
Comment: It doesn't look like there is any hope Winds of Winter will be coming out this year: https://twitter.com/JaneJohnsonBakr/status/426815126818127872
Comment: Nice answer. You might want to add the latest novella, The Rogue Prince.
Comment: @SystemDown You may want to update this answer to include "The Sons of the Dragon".
Answer: tl;dr: You probably don't need to read them at all, they are exactly the same as the chapters in the novels.

The novellas do not actually contain any additional plot or character information, they are just the relevant chapters from the novels, extracted into a novella so Martin could submit them for HUGO awards.
If you have read all of A Game of Thrones then you have already read all of Blood of the Dragon, etc.
If you read the novellas first, they will spoil the novels. If you read the novellas second, you will probably be bored. However, if you found Dany or Damphair particularly interesting characters in the novels, you may find it interesting to see their chapters as one continuous story, uninterrupted by rampaging Joffreyness.
Answer: A Feast for Crows and A Dance with Dragons cover the same period of the story, but are divided by the characters they include. Half of the characters didn't appear in AFFC, and you had to wait to read ADWD to get their stories. Then two-third of the way through ADWD the storylines catch up with each other and you get all the characters again.
Some fans have come up with a combined reading order for AFFC and ADWD, which joins the books together into a 119 chapter monstrosity. While probably most people who read it this way have already read the books before, some people do say that it is a good way for the first time readers too. Surprisingly, only two chapters need to be put out of order to prevent spoilers. Some other fans have taken that list to produce a combined ebook, which I won't link to here.
Answer: In my answer describing the levels of canon in the series I list all of the published and unpublished works so far. However, for the purpose of the reading order I'll only add the published works as we'll get a better idea of how they fit into the story later on.

The answer by @System Down gives the generic reading order for the books either chronological or publish order. I will give a slightly different order and say you should read them as follows.

A Game of Thrones
A Clash of Kings
A Storm of Swords
A Knight of the Seven Kingdoms (The Hedge Knight, The Sworn Sword, The Mystery Knight)
A Feast for Crows
The Rogue Prince
The Princess and the Queen
A Dance with Dragons
The Sons of the Dragon
The World of Ice and Fire

In this order you get the initial novels from the main series to set up the universe without being too heavy. You then get a natural break in the main ones after ASoS and the next two books contain a lot of references to the D&E series. Afterwards you could read TRP/TPatQ or AFfC, I've seen them swapped around in different orders. However, I prefer the order I've shown because you get to start back into the series again and then ADwD makes a bit more sense due to the prequel novellas. Lastly, I would read TSotD and TWoIaF as they give a nice back story and history lesson to the world.
I have seen other orders that suggest leaving TRP and TPatQ until after ADwD so they act as prequel novellas similar to TSotD. It all really depends on personal taste.
One thing I would note though is get a copy of The Lands of Ice and Fire if you want a better feeling for where everything is happening. It's just a collection of maps and would be nice to use alongside reading.

The three novellas you link in the OP are actually inspired from chapters off of the main series as such you do not need to read them. However, there are some differences in them (the linked reddit posts discuss these) so if you really want to read them I'd add them in after reading the book they were inspired from or at the end.

Blood of the Dragon: Daenerys chapters from A Game of Thrones
Path of the Dragon: Daenerys chapters from A Storm of Swords
Arms of the Kraken: Four chapters with PoVs from the Iron Isles from A Feast for Crows
Comment: +1 This is probably the best order. There were a *heck* of a lot of little details in A Feast For Crows and beyond where when I first read them, not having read the "Knight of the Seven Kingdoms" stories, I felt they were an annoying tangent from the storylines I was interested in and didn't pay much attention - but after I had read those stories, I appreciated the depth and clues about interesting mysteries and possibilities relevant to the main story. I'd have got a lot more out of AFFC and ADWD if I'd read the short stories first.
Answer: It doesn't really matter what order you read the books / Novels, because every set (ASOIAF Books, Tales of Dunk and Egg and the duo The Rogue Prince + the Princess and the Queen) can be considered as a standalone saga. I personally saw the first season of Game of Thrones and right after it ended I read all four books that were out at the time (A Game of Thrones, A Clash of Kings, A Storm of Swords and A Feast for Crows), later on I read A Dance with Dragons as it was released. Then I moved to the Tale of Dunk and Egg (The Hedge Knight, The Sworn Sword and The Mystery Knight). A few weeks ago I discovered The Rogue Prince (finished it in a few hours) and now I'm reading The Princess and the Queen. Recently there was another novel that was released by Martin that focuses more on the History of the continent - The World of Ice and Fire, I will check it out the moment I finish The Princess and the Queen. If you want to move chronologically than read The World of Ice and Fire and move on like System Down mentioned in the answer above. The important part is not the chronological time when every saga happened because like I mentioned there are very small connection between the novels and the books. When you take every saga of novels / books you need to go like:
If you choose to read the Song of Ice and Fire Books then read:

A Game of Thrones
A Clash of Kings
A Storm of Swords
A Feast for Crows
A Dance with Dragons

If you choose to read the Tales of Dunk and Egg then read:

The Hedge Knight
The Sworn Sword
The Mystery Knight

If you choose to read the Rogues + The Princess and the Queen then read:

The Rogue Prince
The Princess and the Queen

If you choose to read The World of Ice and Fire then:
I haven't read The World of Ice and Fire but from what I heard it's a standalone novel so you can read it at any time.
Comment: TWOIAF is not a standalone novel it is more of a History & Geography book. I would suggest that it be read at the very end as it covers all the events from the Age of Dawn till the coronation of Robert I Baratheon.
Answer: I know it has been a few years since these comments, so here is a small update from what I have recently read online. As of late 2017, a prequel novella called The Sons of the Dragon has hit the shelves. This one takes place before The Rogue Prince, in the years immediately following the conquest. This one takes place two generations before The Rogue Prince, which in turn leads directly into The Princess and the Queen.
All three in chronological order, The Sons of the Dragon, The Rogue Prince, and The Princess and the Queen, will be released in October of 2018 in a collection titled, Fire and Blood (similar to A Knight of the Seven Kingdoms), though with even more details. While Princess and the Queen was 35,000 words, Fire and Blood will boast over 80,000...though much of that difference comes from the other two novellas.
What we can expect in the future is largely dependent on what Martin has already written, and his questionable health. While he claims to be ever working on the much delayed and anticipated, The Winds of Winter, he also claims that after TWOW, a second volume of Fire and Blood will be following. Hopefully that entails filling in the gaps left by the end of the Princess and the Queen and beginning of The Mystery Knight.
In that gap are the reigns of at least 5 Targaryen Kings and the first 2 Blackfyre Rebellions, fueled by the rivalry of two of Aegon the IV's Great Bastards, the infamous Bloodraven (Brynden Rivers) and his half-brother Bittersteel (Aegor Rivers).
GRRM has stated he also plans to extend the Dunk and Egg novellas by several volumes, so that in total there may be 12 Dunk and Egg novellas, detailing much of the 90 years between A Knight of the Seven Kingdoms and book 1, a Game of Thrones. In those years, the mystery of Summerhall takes place as well as the mystery of Sir Duncan the Tall's elusive relationship. GRRM has said that one of Dunk's decedents is a character in the present storyline.
Comment: Hello Greg, and welcome to [fantasy.se]. Do you think you can dig up _where_ you read this online? You can [edit] your answer to add this information. Meanwhile, may I invite you to take the [tour]?