Why does the Buddha call himself the Tathāgata?

Question: Questions in the title. What is the significance of this term and how it is used by the Buddha in the suttas?
Answer: From an academic perspective the wikipedia article "Tathāgata" has good information. According to wikipedia:
The word's original significance is not known and there has been speculation about it since at least the time of Buddhaghosa, who gives eight interpretations of the word, each with different etymological support, in his commentary on the Digha Nikaya, the Sumangalailasini:

He who has arrived in such fashion, i.e. who has worked his way upwards to perfection for the world's good in the same fashion as all previous Buddhas.
He who walked in such fashion, i.e. (a) he who at birth took the seven equal steps in the same fashion as all previous Buddhas or (b) he who in the same way as all previous Buddhas went his way to Buddhahood through the four Jhanas and the Paths.
He who by the path of knowledge has come at the real essentials of things.
He who has won Truth.
He who has discerned Truth.
He who declares Truth.
He whose words and deeds accord.
The great physician whose medicine is all-potent.

Modern scholarly opinion generally opines that Sanskrit grammar offers at least two possibilities for breaking up the compound word: either tathā and āgata or tathā and gata. Tathā means thus in Sanskrit and Pali, and Buddhist thought takes this to refer to what is called reality as-it-is (yathā-bhūta). This reality is also referred to as thusness or suchness (tathatā) indicating simply that it (reality) is what it is.
A Buddha or an arahant is defined as someone who "knows and sees reality as-it-is" (yathā bhūta ñāna dassana). Gata "gone" is the past passive participle of the verbal root gam "go, travel". Āgata "come" is the past passive participle of the verb meaning "come, arrive".
Thus in this interpretation Tathāgata means literally either "the one who has gone to suchness" or "the one who has arrived at suchness".
Another interpretation, proposed by the scholar Richard Gombrich, is based on the fact that that, when used as a suffix in compounds, -gata often loses its literal meaning and signifies instead "being". Tathāgata would thus mean "one like that", with no motion in either direction.
According to Theodore Stcherbatsky, the term Tathagata has a non-Buddhist origin, and is best understood when compared to its usage in non-Buddhist works, such as the Mahabharata. Stcherbatsky gives the following example from the Mahabharata:

Just as the footprints of birds (flying) in the sky and fish (swimming) in water cannot be seen,
    Thus (tātha) is going (gati) of those who have realized the Truth.

Buddha uses the term to refer to himself rather than saying, I, me or myself.
Comment: Mahabharata is obviously post Buddhism. Also, the word gati appears to be a verb.
Answer: Tatha means "truth", "reality" or literally "so", "such".
gata is often translated as gone, however from my research it looks like it is a suffix that means "firmly grounded in" or "rooted in" -- as in kayagata smrti "mindfulness rooted in the body".
Together this would make Tathagata mean "Firmly established in reality".
I personally associate this word with two other terms: sugata and duggata.
Sugata is a person who fared well, a lucky one, and therefore an optimist.
Duggata is an unfortunate person, a loser, and therefore a pessimist.
Tathagata would then mean neither a pessimist nor an optimist, but realist.
Comment: how about interpreting 'gata' or 'gone' as past participles in other Indo-European languages: 'well-behaved' meaning 'behaving well', or 'ill-mannered' etc?  then 'tathagata' means simply one who goes by reality/truth, sticks to reality/truth. well I guess full mindfulness amounts to the same.
Comment: Or for example "**ārāma-gata**, mfn., *having gone to or being in a monastery*" -- saying that "gone to" and "being rooted in" are the same.
Comment: https://suttacentral.net/dn29/en/sujato
Comment: reasonable answer but rather tenuous statement derived from kayagata smrti. Mindfulness cannot be rooted in the body. Mindfulness means remembrance. Mindfulness can only recollected mental phenomena.
Comment: Repeating a poem to learn it by rote is also called sati/smrti. Repeating recollection of applying attention to the bodily phenomena is mindfulness rooted in the body, established onto the body.
Answer: 1. Why does the Buddha call him self Tathāgata?
What would be better than showing the man's own words?

"Whatever in this world — with its devas, Maras, & Brahmas, its
  generations complete with contemplatives & brahmans, princes & men —
  is seen, heard, sensed, cognized, attained, sought after, pondered by
  the intellect, that has been fully awakened to by the Tathāgata. Thus
  he is called the Tathāgata.
"From the night the Tathāgata fully awakens to the unsurpassed Right
  Self-awakening to the night he is totally unbound in the Unbinding
  property with no fuel remaining, whatever the Tathāgata has said,
  spoken, explained is just so (tathā) and not otherwise. Thus he is
  called the Tathāgata.
"The Tathāgata is one who does in line with (tathā) what he teaches,
  one who teaches in line with (tathā) what he does. Thus he is called the
  Tathāgata.
"In this world with its devas, Maras, & Brahmas, its generations
  complete with contemplatives & brahmans, princes & men, the Tathāgata
  is the unconquered conqueror, all-seeing, the wielder of power. Thus
  he is called the Tathāgata.
  -Iti 4.13, Discourse on the World (Lokasuttaṃ)

In addition to the above, DN 29 provides one more definition:

'If "the past" refers to what is not factual, not true (atathā), to what is
  not of advantage, the Tathāgata makes no reply. If it refers to what
  is factual, true (tathā), but which is not of advantage, the
  Tathāgata makes no reply. But if "the past" refers to what is factual, true (tathā), and which is of advantage, then the Tathāgata
  knows the right time to reply. The same applies to the future and the
  present. Therefore, Cunda, the Tathāgata is called the one who
  declares the time, the fact, the advantage, the Dhamma and the
  discipline. That is why he is called Tathāgata.'
  -DN 29, Delightful Discourse (Pāsādika-suttaṃ)

2. What is the significance of the term?
As the Wikipedia states:

Modern scholarly opinion generally opines that Sanskrit grammar offers
  at least two possibilities for breaking up the compound word: either
  tathā and āgata or tathā and gata. Tathā means thus in
  Sanskrit and Pali, and Buddhist thought takes this to refer to what is
  called reality as-it-is (yathā-bhūta). This reality is also referred
  to as thusness or suchness (tathatā) indicating simply that it
  (reality) is what it is.
A Buddha or an arahant is defined as someone who "knows and sees
  reality as-it-is" (yathā bhūta ñāna dassana). Gata "gone" is the past
  passive participle of the verbal root gam "go, travel". Āgata "come"
  is the past passive participle of the verb meaning "come, arrive".
Thus in this interpretation Tathāgata means literally either "the one
  who has gone to suchness" or "the one who has arrived at suchness".
  -Tathāgata Wikipedia Page

So it appears these two meanings can be derived from the word. I think some light can be shed by seeing the word used in another context in which there can only be one meaning due to the nature of it's context (simile):

In ancient times when seafaring merchants put to sea in ships, they
  took with them a bird to sight land. When the ship was out of sight of
  land, they released the bird; and it flew eastward and westward,
  northward and southward, upward and all around. And if the bird saw no
  land, it returned to the ship; but if the bird sighted land nearby, it
  was truly gone (tathāgatakova).
  -AN 6.54, Discourse about Dhammika (Dhammika-suttaṃ)

Note that footnote nº2 of the above discourse is also worth reading to get a better grip on it's meaning.
3. How is the term used by the Buddha in the suttas?
As user70 pointed out, the Buddha usually uses the term to refer to himself. Above, I quoted a number of prosaic contexts that reveal how he uses the term, so I'll leave a poetic reference for this answer.
    Just this
    is the path
 - there is no other -
to purify vision.
    Follow it,
and that will be Mara's
    bewilderment.

Following it,
you put an end
to suffering & stress.
I have taught you this path
having known
 - for your knowing -
the extraction of arrows.

It's for you to strive
    ardently.
Tathāgatas simply
point out the way.
Those who practice,
absorbed in jhana:
    from Mara's bonds
    they'll be freed.

-Dhp v275-276
Comment: Excellent quotes.
Answer: A Tathagata is one who is neither coming or going. That is neither going to the other side or coming back. Because there are no longer sides. Just what is.
Answer: tathāgata
tatha: (being) in truth,truthful; true,real
ā: to,towards
gata: directed to
*canonics
Answer: Unrul3r's answer includes that it might mean going or coming (gata or agata).
Andrei's answer is that it means 'grounded' or 'rooted' (which makes sense to me: because if you go or come, have gone or have come, to somewhere then that is where you are).
Combined (and further to user319's answer) these remind me of a Zen story --  using Google I cannot find a reference to it at the moment, so I paraphrase it:

Someone, who is dying, says, "We come from nowhere, and we go to nowhere."
His companion, to be helpful, replies, "Let me show you the road, where there is no 'coming' and no 'going'."
Answer: Tathagata is one who will not be reborn. In the Sutta the word is used only for Sammasambuddha. It cannot be separated as Tatha + Agata; or Tatha + Gata. It is Tathaa + gata.
A Tathagata has stopped 'moving' is Sansara.
Comment: Hello. The suttas literally say the Tathagata is not not-reborn. MN 72 says 'They're not reborn' doesn't apply, Vaccha." "Na upapajjatīti kho, vaccha, na upeti".
Answer: My guess for this question is Tathāgata means "arrived at/come to the truth/reality".
The Pali Dictionary say the origin & etymology of Tathāgata is unknown, including to Buddhaghosa:

Derivation uncertain. Buddhaghosa (DN-a.i.59–DN-a.i.67) gives eight
explanations showing that there was no fixed tradition on the point,
and that he himself was in doubt.

It appears there are two possible derivations:

tatha + āgata = reality/truth come/arrived
tathā + gata = thus gone

The seemingly unambiguous contextual non-Buddha use of the term in AN 6.54 seems to explain the term, as follows:

"Sir, I've been banished by the local lay followers from all seven
monasteries in my native land."
"Pabbājito ahaṁ, bhante, jātibhūmakehi upāsakehi sabbaso jātibhūmiyaṁ
sattahi āvāsehī"ti.
"Enough, Brahmin Dhammika, what's that to you? Now that you've been
banished from all of those places, you have come to me.
"Alaṁ, brāhmaṇa dhammika, kiṁ te iminā, yaṁ taṁ tato tato pabbājenti,
so tvaṁ tato tato pabbājito mameva santike āgacchasi.
Once upon a time, some sea-merchants set sail for the ocean deeps,
taking with them a land-spotting bird.
Bhūtapubbaṁ, brāhmaṇa dhammika, sāmuddikā vāṇijā tīradassiṁ sakuṇaṁ
gahetvā nāvāya samuddaṁ ajjhogāhanti.
When their ship was out of sight of land, they released the bird.
Te
atīradakkhiṇiyā nāvāya tīradassiṁ sakuṇaṁ muñcanti.
It flew right away to the east, the west, the north, the south,
upwards, and in-between.
So gacchateva puratthimaṁ disaṁ, gacchati pacchimaṁ disaṁ, gacchati
uttaraṁ disaṁ, gacchati dakkhiṇaṁ disaṁ, gacchati uddhaṁ, gacchati
anudisaṁ.
If it saw land on any side, it went [arrived] there and stayed.
Sace [if] so [he; the bird] samantā [everywhere] tīraṁ [shore] passati [sees], tathāgatako [truely arriver/comer] va hoti [is a].
But if it saw no land on any side it returned to the ship.
Sace pana so samantā tīraṁ na passati tameva nāvaṁ paccāgacchati.
In the same way, now that you've been banished from all of those
places, you have come to me.
Evamevaṁ kho, brāhmaṇa dhammika, yaṁ taṁ tato tato pabbājenti so tvaṁ
tato tato pabbājito mameva santike āgacchasi.

āgacchati = comes,
comes near; comes back, returns; reaches, attains, arrives
pp āgata

Alternately, the independent Australian translator Sujato on Sutta Central asserted the use of "tathāgata" in AN 6.54 is unrelated to the use of tathāgata as the Buddha's name. The impression is, for Sujato, tathāgata as the Buddha's name means "arrived/come to the truth" but in AN 6.54 tathāgata means this bird has "thus gone/flown". Sujato said:

Oh, and to forestall the obvious, no this doesn't have anything to do
with tathāgata as an epithet of the Buddha. The terms in this compound
are extremely common and occur in a wide variety of senses. As an
epithet of the Buddha, the primary sense is "one who has realized the
truth". How to translate 'tathāgatakova'?

To me, it seems plainly obvious the analogy in AN 6.54 logically is about the bird & thus the ship arriving/coming to land, just as the ex-Brahmin had come to the Buddha. There is the word 'āgacchati' about the ex-Brahmin coming to the Buddha and the past participle of āgacchati, namely, āgata, in the term 'tathāgatakova' about the bird/ship coming/arriving to land.
To conclude, for me, Tathagata means 'come to the truth'; derived from tatha + āgata.
Thus Iti 112 says, per Sujato translation:

In this world—with its gods, Māras, and Brahmās, this population with
its ascetics and brahmins, its gods and humans—whatever is seen,
heard, thought, known, attained, sought, and explored by the mind, all
that has been understood by the Realized One.
Yaṁ, bhikkhave, sadevakassa lokassa samārakassa sabrahmakassa
sassamaṇabrāhmaṇiyā pajāya sadevamanussāya diṭṭhaṁ sutaṁ mutaṁ
viññātaṁ pattaṁ pariyesitaṁ anuvicaritaṁ manasā yasmā taṁ tathāgatena
abhisambuddhaṁ,
That's why he's called the 'Realized One'.
tasmā 'tathāgato'ti vuccati.
From the night when the Realized One understands the supreme perfect
awakening until the night he becomes fully extinguished—in the element
of extinguishment with nothing left over—everything he speaks, says,
and expresses is real, not otherwise.
Yañca, bhikkhave, rattiṁ tathāgato anuttaraṁ sammāsambodhiṁ
abhisambujjhati, yañca rattiṁ anupādisesāya nibbānadhātuyā
parinibbāyati, yaṁ etasmiṁ antare bhāsati lapati niddisati, sabbaṁ taṁ
tatheva hoti no aññathā,
That's why he's called the 'Realized One'.
tasmā 'tathāgato'ti vuccati.
The Realized One does as he says, and says as he does.
Yathāvādī, bhikkhave, tathāgato tathākārī, yathākārī tathāvādī,
Since this is so,
iti yathāvādī tathākārī yathākārī tathāvādī,
that's why he's called the 'Realized One'.
tasmā 'tathāgato'ti vuccati.
Answer: I cannot seem to find in which Sutta this is said, but...
The Blessed One said once: Bhikkhus, the world has been discovered by the Perfect One, he has dissociated from the world. The origin of the world has been discovered by Him. He has abandoned the origin of the world. The cessation of the world has been discovered and He has realised the truth. In the world with its deities and others, whatever can be seen, heard sensed and cognized or reached, sought out and encompassed by the mind, has been discovered by the Perfect One that is why He is called a Perfect One (The Thathagatha). The Most Enlightened.


If I delete synced Google contacts on my iPhone, does that affect my google contact?

Question: I needed some of my gmail contacts to email them and get some info, so I decided to sync my google accounts to my iPhone.
The problem is that I have some repeated contacts and I want to delete those from the iPhone, but I don't know if that will just delete them on the phone or if it'll affect my google contacts too.
Comment: Firstly, welcome to Ask Different! :)  I hope you come to find this site has a lot to offer! In case you haven't already, it's worth taking the time to read the [tour](https://apple.stackexchange.com/tour). All the best with your question!
Comment: For my knowledge, if you delete it using the contact app from iPhone it will delete from google contacts. You have the option to link the duplicated ones (considering they are not too much, because you have to do it one by one). Is linking them a valid option for you? Linking is like merging both contacts details into one person showing on iPhone's Contact App; In other words: Your problem is having 2 repeated contacts showing on iPhone (which is annoying), or your problem is that you want to not have duplicates at all [between google contatct and iPhone contatcs]?
Answer: If you're only seeing the duplicates on your iPhone, they're most likely in different Groups. You can check this by opening Contacts on your phone and tapping the Groups button (screenshot below). If you see a group called iPhone, those are stored exclusively on your phone and deleting them will not affect your Google contacts. You can uncheck the Google group to show (and ensure you only delete) contacts from your phone. Deleting contacts from the Google group will affect your Google contacts.


Is there a way to calculate mass flow rate of an axial compressor?

Question: Is there a rule of a thumb equation for the mass flow rate of a stationary axial compressor at sea level, using intake area and RPM? Or do other factors like blade geometry make too much of a difference for such an approximation to be possible?
Comment: shape of the intake...
Answer: In theory, there is. Every fan can be described by characteristic numbers. One is the delivery number $\phi$. It describes the ratio of acutall air flow to theoretical air flow, as given by area and speed and is defined as:
$$ \phi = \frac{4\dot{V}}{u\pi d^2}$$
with $\dot{V}$ as volume flow rate in m³/s, u fan speed at circumference in m/s and d fan diameter in m. Knowing fan geometry and rpm, you can calculate u, knowing density, you arrive at $\dot{V}$ so if you know $\phi$ you could calcualte air-flow fom rpm.
The problem is that you will be ahrd pressed to find delivery numbers for fans (They are usually not given in spec sheets IIRC).
Answer: The design of the compressor makes all the difference. Shape of the blades, number of stages, design of the stators, and the material heat resistance.
Increasing the pressure of the air increases it's temperature so the material properties is a constraint.
There is a compromise between compressors designed for performance, and others designed for reliability. If one goes for maximum mass flow rate, the compressor could stall.


When should I be using wallride?

Question: I feel like using wallride is never really necessary when playing Lúcio, as just running around normally works just fine. I occasionally do it just for fun running places, but I haven't found any real purpose for using it in game. So, when should I be using wallride, and what advantages does it have?
Comment: Did you watch the video on his Hero Information page? You can wallride surprisingly far.
Comment: @DCShannon yea, i know you can go pretty far, but other than being fancy what else is it used for?
Comment: Well, in the video he uses it to get from one walkway to another in a way that would be impossible by walking. Crossing a big gap, basically. I haven't got to the point where I'm using it regularly even after 5 hours of Lucio playtime, but I figure I will eventually.
Comment: @DCShannon oh, apparently you can get out of the well in Ilios with it, and I guess crossing large gaps can be useful, but to me I still don't it really being all that useful. Maybe someone else will have figured when to use it during normal gameplay.
Comment: Yeah, that's pretty much where I'm at. It seems useful intellectually, but I have yet to figure out how to use it on a regular basis in actual games.
Comment: https://www.youtube.com/watch?v=YH0ePK5ia50
Answer: When to use it? Always!
It is not only for being fancy, and it's not exactly situational either, because it's almost always better to fly around than to walk around like a mere mortal. It's a movement ability, and like all movement abilities it's really good, but this one is pretty hard to learn how to use effectively.
Wall-riding is about so much more than crossing a gap, and that has a lot to do with the fact that you can chain them. That is a bit of a confusing in the beginning of course. You can get an extra jump off the wall and continue on another wall, so in essence, with some practice you can scoot around the top edges of the map once you get a hang of it. Watch some videos like other people suggested, or just practice in a custom game, and you will eventually see that it is very useful for navigating, for escaping or distracting etc.
I can't see anyone that's not using it be a truly effective Lucio, since it's actually one of the best movement skills in the game!
Also, remember that everyone is kind of new to this game. We had quake for a long time before people started bunnyhopping, and this is a thing that requires some finesse, so the wall-riding may well have a lot of potential that we don't know about yet.
Answer: 'When' you should be using wallride is more of a personal opinion.
To answer your question on its advantages, as well as for the reasons shown in the video posted in another answer, Lucio's wall ride can provide specific advantages over your opponents for a variety of reasons.
Planet Overwatch's video shows an introductory guide to Lucio's wall riding ability.
Not only can the ability be used to 'climb' walls in order to get to higher points of the map usually inaccessible to most characters, you can use it glide along walls, gaining momentum and pace as you do so.
Using a combination of some of the techniques show in the video allows you to drop down on enemies from a great height, usually in ways they are not expecting, giving you the element of surprise when capturing zones etc.
There are many guides on youtube showing the basics of Lucio's ability, as well as more advanced video on how to use it effectively in game.

I'm glad you asked the question, because until now I had no idea how to use it effectively either.
Answer: One caveat I feel hasn't been mentioned in previous answers is that wallriding increases your field of movement. It's harder to headshot* a Lucio in a corridor than, say, a Tracer if Lucio uses his wallrides, jumps and movement abilities erratically.
I've been able to approach and kill Hanzos and Widowmakers by using wallride jumping while I know they're looking my way.
*unless you're one of those people that can pin a fly to a dartboard while blindfolded and being tickled.
Answer: As seen in this video, you can use it to escape the well in Ilios by running around in circles until you reach the top. This can be somewhat helpful if a Roadhog drops you in, but you may end up dying anyway if your team doesn't have control of the point when you get out.
Comment: That's a good example. I think the essential answer might be "to move in areas where there's no floor, but there's a wall".
Comment: Not only that, but whenever I see a Lucio trying it, as D-VA I will intentionally jet down into the well and back up to make them fall, since they're a "free kill."
Answer: Wallriding by itself is not very usefull.
However when you combine your wallride with well timed jumps, speed boost and Amp It Up you can get to crazy places insanely fast. You can then utilize this to escape certain death situations (as Dragonrage posted), to get to your teammates to help them or to evade incoming enemy fire.
Here's a video demonstrating advanced Lúcio wallriding techniques.

When should I be using wallride?


Why use cross notes in sheet music for hip hop tracks?

Question: This is an excerpt from the sheet music for a song by Eminem. What do the cross notes mean, and what is their purpose? Why not use normal notes? (I see this frequently in hip-hop sheet music.)
Answer: They refer to non-tonal/non-harmonic sounds; be it drum sounds (these sounds don't follow a harmonic structure), or dead notes on a string instrument, or, as is the case in this example, rap (the rapper speaks the words without tuning them to a specific pitch).
This is useful for notating rhythm parts that don't really have a pitch. It's used instead of "normal notes" because it would be misleading to notate the example as, say, a B if the performer isn't supposed to sing a specific pitch.
They are actually called "Ghost Notes". In Wikipedia you can see a few examples of parts notated with these notes.
Comment: Ok and this what differs with dead notes?
Comment: Do you mean the dead notes you would play on a guitar? They are another example of parts that are notated with these ghost notes (it's equivalent to using the guitar as a percussion instrument, playing non-tonal sounds). I've edited my answer with additional information.
Comment: Excellent with great help was your answer.
Comment: Drum sounds do kind of follow a harmonic structure, similar to the notated rap here. They are usually not tuned to specific pitches (although toms sometimes are and timpani certainly are). There is a hierarchy though in that some of the drums are tuned higher than other, which also applies to smaller/larger cymbals.

You can hint at inflections using this kind of notation for rap as well, if one cross note is higher than another, it is of a higher relative pitch, although it isn't specified exactly what either of those pitches are.


why don't popular tokens have payable fallback

Question: I'm referring to the source of of the most popular tokens on etherscan.
It looks like they don't have any payable functions.
How do they accept ether and transfer the tokens automatically when someone sends ether to the contracts?
Answer: The fallback function (accept-payment-by-default) is bad, becase

It allows easily the buyer to make a payment from incompatible wallet (Coinbase)
It prevents doing any meaningful KYC/AML/other tracking on token sale participants

As experience over dozens of token sale, I strongly advise against having a fallback payable Ethereum smart contract. If you do have you are just greedy and screwing over technically incompetent audience.
As an alternative, I recommend using web3.js wallet like MetaMask and having a single click "Pay with MetaMask" button.
The extended discussion can be found here:
https://github.com/TokenMarketNet/ico/issues/53
Answer: One of good basic qus in Eth community.
Almost all popular tokens are listed in exchanges. While listing in exchange token owner(company) will give some commission(most of exchanges will charge for service) for listing token into the exchange. Once your place an order via exchange with some X Eth, exchange will take the responsable for transfer Eths to Company Eth account or convert Eth to fiat money and transfer to company account. So token owner no need to worry about the process, and he can able to change account for every exchange, If some one hacked one account, remaining accounts will be safe. And every exchange has own rules and laws.
So thats a reason they didn't mention any payable function. If you want to enable users to buy eths from their accounts you can provide or any other contract called your non exists method EVM will look for fallback function. In that you can do what ever you want.
Answer: The idea of a fully Ethereum-based ICO is one of the more romanticized ideas in the community. That is to say, it's the ideal and not the norm. In practice, many ICOs simply issue tokens, rather than having you perform a transaction on the Ethereum network in order to buy in. Why? There are a few good reasons.
First, ICOs are legal grey area. In the United States, on December 11, 2017, the Securities and Exchange Commission issued a notice that ICOs had to comply with securities laws. Because they're technically investments, many countries regulate how legal investments can be made -- paying particular attention to the risk that an investor makes when buying in. Many countries try to limit the damage from convincing so called "unaware buyers" from entering into investments that they don't understand, and then losing big time. This can create devastating losses that people aren't prepared for.
Second, many ICOs are launched with the intention of being bought through other platforms. As the first answer indicated, it can be that they would rather be sold on exchanges and then have tokens issued in bulk in order to simplify the process of running the ICO. Filecoin's ICO is a great example of this. Exchanges can handle compliance problems like KYC/AML and also shoulder some of the support burden from running one.
So, to summarize: ICOs are a complicated breed of investment with a lot of risks and a lot of technical issues that have to be accounted for during the process. A strictly ethereum contract based ICO where you can simply pay for tokens is idealized by the ethereum platform, but not necessarily the most applicable to reality.


is this a rose quartz

Question:
pink quartz looking stone 19 pounds found in a vehicle in new york state
Comment: Judging only from the picture, it almost certainly is rose quartz.
Comment: Please add more information following [this guide](https://earthscience.meta.stackexchange.com/a/125/725).
Answer: Yes, it is rose quartz. There are a number of mines in eastern New York near Vermont where rose quartz been found. Massive rose quartz can occur in granitic pegmatites.  I could not google to find images of any massive rose quartz from the northeastern United States but it is very similar in appearance to the rose quartz from Black Hill of South Dakota.  The rose quartz deposits from the Black Hills are the largest on earth and the material is sold world-wide.  Locally here in Ohio, I know of the landscaping company that has bulk rose quartz for sale.
You're specimen might be local to New York but might also be from elsewhere.
See Mindat.org
Comment: thank you we in central new york i wish the camera could pick up the colors better it is really pink in color thank you for your help

is this a rose quartz


How do I check if a block region is empty?

Question: I'm wanting to apply some specific CSS on the condition that a block region is empty. How do I make this check?
Answer: An update on this. I used the solution at https://drupal.stackexchange.com/a/73685/56728 as follows
  module_load_include('inc', 'block', 'block.admin');
  global $theme_key;
  $blocks = block_admin_display_prepare_blocks($theme_key);
  //test for a named block's (here the help block) visibility
  foreach($blocks as $block){
    if($block['delta'] == 'help' && $block['region'] != -1){
      sdpm($block['delta']. " is visible!");
    }
  }

This detects whether the block is visible or not, but does not quite do what I'm after which is to test for the visibility of a given block on the current "page" for the current user. That to me sounds like what block_list() does, but I'm stumped by block_list() as I mentioned above. My "solution" also very likely not the most elegant way of doing things so any help from experts out there would be greatly appreciated. Nat
Answer: If you're in you're in a page template you can check your $page region variable for an empty an array of block objects.
if (empty($page['my_region']) { /*DO STUFF*/ }

If you're in another context you can use the block_list function to determine this.
$blocks = block_list('my_region');
if (empty($blocks)) { /*DO STUFF*/ }


Where can I get a frame for a 4x18" panoramic print?

Question: I know a specialist framing shop can make custom frame sizes but are there any places that make this frame size as a pre-set item, for a panorama?
Comment: Flagged as 'too localized' as there are different answers depending on locale.
Comment: Google it for online options or go to any store that will custom make frames locally if they don't already carry your favorite size. This applies to every size, not just 4x18. I don't think we need every size under the sun asked here on this website, especially since we don't live in the same place.
Comment: I know you have your web site where you sell prints in odd sizes. Are you looking for a supplier for that? Maybe some further explanation in the question would help the naysayers here.
Comment: @mattdm,yes. Basically I sell 4x18" prints (without frames) and so customers regularly ask where they can buy frames. Google is a bit thin on results so I was hoping you bright people might have some clever ideas ;-)
Comment: I just did a 8x32" panorama which I made into a 10x34" framed print. The print cost less than $20 at Bay Photo and my local Hobby Lobby charged a total of around $50 for dry mount, matting, glass, and I assembled my own frame rails (as mentioned in comments below).
Answer: You can get a frame intended for 3 landscape 4x6" photos and then get a bespoke mount.
I saw some Nielsen frames in UK shop called "Athena". They also cut the mounts for £5.

Does anyone have any better suggestions?
Comment: I have done this approach with good success along with also finding low priced, pre-made, frames in such things as wall mirrors (removing the mirror glass of course). Wall mirrors also tend to be made in odd sizes and even found at places like garage/yard sales.
Answer: Professional framing suppliers like Pictureframes.com will sell you the components for whatever size you want. Metal frames are usually sold in pairs of sides, so for a 4x18" frame, you would order a 4" pair and an 18" pair. The sides are then easily assembled with hardware they provide. They will also cut glazing, backing, and matting to whatever size you need.
Comment: I really like my local Hobby Lobby or Michael's stores. They carry these frame sides in pairs as mentioned along with the other hardware. Albeit, you are very likely to find cheaper prices online, I also have Hobby Lobby do my dry mounting, matting and cutting of the glass. A total one-stop experience. To save some more cash, you can go to a home improvement store for the glass. They should even cut it down to size for you in store.
Answer: If you google 4X18 frame, several results come up. Most are for the same brand name, Craig, and are fulfilled by Sears/K-mart.
http://m.kmart.com/productdetails.do?partNumber=021V003618448000P
http://www.sears.com/craig-frames-inc-4x18-custom-1.25inch-wide-complete/p-021V003601878000P
http://www.shopping.com/craig-frames-inc-4x18/DhVztcxF7HhULoCozz9gTQ==/info
http://shopping.aol.com/craig-frames-inc-4x18-custom-15-wide-black-wood-picture-frame-15driftwoodbk/pg879124738
If you want a frame large enough for a matte around your 4x18 photo, then you would of course need to find a larger frame. A two inch matte would require an 8x22 frame. A google search for "8x22 frame" yields results from the same sources as the 4x18 search.


Model Validation problem in ASP.NEt MVC 2 RC 2

Question: I have facing the following problem after the update.
I have a Model with Class level Validation plus property level validation in it. After updating to MVC 2 RC 2. The model validation fails on Model binding. What i actually understand that new mechanism trying to validate the model when you first request it or say on GET and it get null object exception during tryvalidatemodel Model binding call.
My Model is like this below
<code>[Serializable]
[MetadataType(typeof(InterestClaimMetaData))] //metadata with all properties level validation

//these validations fails when you request a page.
[DateComparison("DateA", "DateB", eDateComparitor.GreaterThan,
    ErrorMessage = "Date A must be greater than B Date")]

[MutuallyExclusive("A", "B", ErrorMessage = "Please select either A or B field")]

public class IE {
    public int ID { get; set; }
    public byte[] Updated { get; set; }
}
</code>
DataComparison and MutuallyExclusive overrides the validate function isvalid and check the validation but it fails trying to validate as first requested.
dont know how to stop this happening as it should not validate model on get request; just attach the properties.
Only models without these class level validation works.
Please advise.
Thanks
Answer: Seperate your action method in your controller in to two action methods.  Mark one as GET and the other as POST.  Then only apply the validation in the POST method.  So, for example, if you currently have an method called Create that looks something like this...
<code>public ActionResult Create(YourModel yourModel)
{
    // Some code in here to validate stuff
    // Some code in here to do stuff
    return RedirectToAction("Index");
}
</code>
Split this out in to two methods like this...
<code>[HttpGet]
public ActionResult Create()
{
    return View();
}

[HttpPost]
public ActionResult Create(YourModel yourModel)
{
    try
    {
        // Some code in here to validate stuff
        // Some code in here to do stuff
        return RedirectToAction("Index");
    }
    catch
    {
        return View();
    }
}
</code>


Russia visa registration when staying on the move

Question: In Russia, the host must register an alien within a week of their arrival (assuming they stay more than a week).  How do independent travellers not staying in hotels at all do?  Do they need to register at all?  For example, I might spend the first three Russian nights on the train and the rest trekking and camping in a national park.  Other people might drive a campervan and use that a a place to sleep.  I have read that If you make the Trans-Siberian route by train and sleep on it, in this case the train ticket would be equivalent to the registration (you always have to keep your ticket in handy). — does that mean the Russian railways register the alien?  Can they also do it if I spend two nights on the train to some domestic destination, without going into any ordinary accommodation from there?  Or can the "inviting company" (which uses a fake itinerary) perform this registration?  How does this work?  Wikivoyage claims that if you do not intend to stay at the hotels, you may, at your own risk, forego the registration procedure, but I'm a bit scared to take their word for it.  What risk?
Comment: It's not quite an answer your question, but [my answer to my question about Russian registration rules](https://travel.stackexchange.com/a/138451/56885), and AussieJoe's comment beneath it, contain some information that might be helpful, depending on how long you plan to be in any given region.
Comment: @ChrisH Ah, my itinerary is longer (3 weeks in total), although I may cross between Komi Republic and Khanty-Mansi Autonomous Okrug during my hike such that I *might* not spend seven consecutive working days in either, but I will be nowhere near any inhabited location in that okrug :-) — however the *question* there includes a quote that explicitly mentions camping, which is interesting.
Comment: Why the downvote?
Answer: Having a long-distance rail or airplane ticket on a date is a proof that you have arrived on that date, so the "n days to register" counter is reset on that date.
I'm not aware that anyone was bothering travelers with registration requirements in the past 15 years, but here you go anyway. If you travel every few days you are virtually extempt from registration rules. Please note that Russian long-distance rail and plane tickets are bound to a specific person so they do in fact "register" your location.


Merge [thermal-printer] into [printer]

Question: Why do we have thermal-printer? Should we merge this in to printer?
Comment: Because programming for them is fundamentally different.  Tough tag, pretty hard to get a helpful vote when you have to explain that they are not going to be done for another month or two.
Comment: @OliverS. As we are in Meta and this post is an actionable request, the downvotes probably indicate disagreement with the request.
Comment: Dunno why the harsh negative vote, legit question but probably needs some research done
Comment: @duplode fair enough
Answer: As Hans Passant points out, "programming for them is fundamentally different". One example I am aware of is zpl -- as the tag wiki tells us, "ZPL stands for the "Zebra Programming Language" and is a proprietary programming language used to communicate to Zebra branded printers". While it is possible that tag cleanup would be appropriate for thermal-printer, it doesn't seem merging it with printer would work well.

Merge [thermal-printer] into [printer]


What's going on in the equation of the variational lower bound?

Question:
I don't really understand what this equation is saying or what the purpose of the ELBO is. How does it help us find the true posterior distribution?
Comment: Can you specify the source of the image?
Answer: From this document, as you found here, $X$ is an observed variable and $Z$ is a hidden variable; $p(X)$ is the density function of $X$. The posterior distribution of the hidden variables can then be written as follows using the Bayes' Theorem:
$$p(Z|X) = \frac{p(X|Z)p(Z)}{p(X)} = \frac{p(X|Z)p(Z)}{\int_Zp(X,Z)}$$
Now base on what you post, if we denote that $L= \mathbb{E}_q [\log p(X, Z)] + H[Z]$ ($q(Z)$ is a distribution we use to approximation the true posterior distribution $p(Z|X)$ in VB and $H[Z] = -\mathbb{E}_q [\log q(Z)]$), then it is obvious that $L$ is a lower bound of the log probability of the observations.
As a result, if in some cases we want to maximize the marginal probability (the log probability of the observations), we can instead maximize its variational lower bound $L$. As a real example, you can follow the "Multiple Object Recognition with Visual Attention" example in the referenced document.
Moreover, the term $L$ will be presented in KL-divergence that will be used to measuring the similarity of two distributions. Be aware that there is progress on the bound in this paper (Fixing a Broken ELBO).
Comment: Your answer seems correct, but I think it will still be difficult for a newbie to understand the ELBO and its motivation. Maybe later I will add a more complete answer.
Comment: @DylanY It is a marginal probability. Indeed, it is used in the concept of KL-Divergence. There, it is related to the concept of entropy that there is a $\log$ in the definition of the entropy.
Comment: You do not explain how $q(Z)$ is related to the last term. What is $H[Z]$? You also do not explain why we would want to maximize $p(X)$.
Comment: @nbro well noted. It is updated.
Comment: what does log of the P(X) get us? Why do they log it?
Comment: do you have any good learning resources on Entropy? I have incomplete idea of what it is and how it helps get the marginal.
Comment: @DylanY I think this link of wikipedia https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence could be helpful.
Answer: The use of KL provides a more intuitive way of what the ELBO is attempting to maximize.
Basically, we want to find a posterior approximation such that $p(z\mid x) \approx q(z)\in\mathcal{Q}$
$$KL(q(z)\parallel p(z\mid x)) \rightarrow \min_{q(z)\in\mathcal{Q}}$$
As a result of this, while finding this optimal posterior approximation, we maximize the probability of all the observed data $x$. Note that the evidence is usually intractable. Thus, can express the $KL$ as follows:
\begin{align*} \log p(x) &= \int q(z) \log p(x)dz \\
&= \int q(z) \log\frac{p(x,\theta)}{p(\theta\mid x)}dz \\
&= \int q(z) \log\frac{p(x,z)q(z)}{p(\theta\mid x)q(z)}dz\\
&= \int q(z) \log\frac{p(x,z)}{q(z)}dz + \int q(z) \log\frac{q(z)}{p(z\mid x)}dz \\ &= \mathcal{L}(q(z)) + KL(q(z)\parallel p(z\mid x)) \end{align*}
In this case, KL just gives us the difference between $q$ and $p$. We want to make this difference close to zero meaning that $q=p$. So, minimizing the KL is the same as maximizing the ELBO, and as a result, we obtain the lower bound in your expression. If you expand your bound, you can find a nice interpretion:
$$ \begin{align*}
\mathcal{L}(q(z)) &= \int q(z) \log\frac{p(x,z)}{q(z)}dz \\
&= \mathbb{E}_{q(z)} \log p(x\mid z) - KL(q(z)\parallel p(z)) \end{align*} $$
When we optimize this expression, we want to find a $q$ that fits our data properly and also is really close to true posterior. Thus, $\mathbb{E}_{q(z)} \log p(x\mid z)$ act as a data term and $KL(q(z)\parallel p(z)) $ as a regularizer.
Comment: I think that the best way to motivate the ELBO is to start from the minimization problem of the KL divergence (which is the actual problem you want to solve), that is, the problem of minimizing the difference between the variational distribution (a supposedly tractable distribution) and the posterior (that you want to approximate with the variational distribution), then derive the ELBO. The motivation should not be that you want to maximize $p(x)$.


Are sockets so slow in PHP?

Question: I'm using this code for sockets. Console says that the page is processed for a very small amount of time, but Chrome says that page is loading for ~1 second!
<code>    $this->serv_sock = socket_create(AF_INET, SOCK_STREAM, 0);

    socket_bind($this->serv_sock, $this->serv, $this->port) or die("Could not bind to address\n");

    socket_listen($this->serv_sock);

    while (1) {
        echo "Waiting...\n";
        $client = socket_accept($this->serv_sock);

        $start_mtime = microtime(true);

        echo "Accepted at ".$start_mtime.".\n";

        $input = '';

        $len = 0;

        do {
            //echo "Reading.\n";
            $inp = socket_read($client, 1024);
            $input .= $inp;

            if (strpos($input, "\n\n") === false && strpos($input, "\r\n\r\n") === false)
                continue;

            if (!$len) {
                if (!preg_match("/Content-Length: (\d+)/", $input, $matches)) {
                    break;
                }
                $len = $matches[1];
                if (!$len)
                    break;
                echo "We want $len bytes.\n";
            }

            if (strpos($input, "\n\n") !== false)
                list($headers, $content) = explode("\n\n", $input);
            else
                list($headers, $content) = explode("\r\n\r\n", $input);

            if (strlen($content) >= $len)
                break;
        } while ($inp);

        echo "Calling callback as ".microtime(true).".\n";

        if (strpos($input, "\n\n") !== false)
            list($headers, $content) = explode("\n\n", $input);
        else
            list($headers, $content) = explode("\r\n\r\n", $input);

        $output = $this->translate($callback, $headers, $content); // nothing slow here

        $time_end = microtime(true);
        echo "Sending output at ".$time_end." (total ".($time_end - $start_mtime).")\n\n";

        $output = "HTTP/1.0 Ok\n".
        "Content-Type: text/html; charset=utf-8\n".
        "Content-Length: ".strlen($output)."\n".
        "Connection: close\n\n".
        $output;

        socket_write($client, $output);

        socket_close($client);
    }
</code>
Answer: If I understand what you're saying. As far as I know there is a difference between server processing time and client processing time.
The time it actually takes to process the information on the server will always be less. Once the server finishes processing the information the data still has to be sent to the browser and has to be rendered. The time for the data to get there and for the browser to render is what I'm suspecting the reason is as to why Chrome is telling you it's taking ~1 second.

Are sockets so slow in PHP?


Finding depression with contour lines

Question: How can I find depression contour lines?
I already have find depressions via Fill-method, but now I try to detect them by using the contour lines, anyone have an idea ?
Answer: This ESRI blog post describes a method for finding depressions using contours. On a topo map depressions look like this:

Note that the above approach is not desgined to be programmatic, but simply relies on symbolizing the contour lines using different colors so that you can visually find lines which do not fit the pattern of stepwise increases.
Comment: thanks for your answers :), but I'm looking for a automatic/programmatic approach
Answer: My opinion is the vector/contour lines are more appropriate for a visual inspection, whereas your original raster is more appropriate for programmatic inspection. Having said that, however...
You might try doing a definition query for the shortest contour lines. As this would designate smaller perimeter measurements, which should be a trait shared by depressions. Of course this will require a heuristic to establish the maximum acceptable length for contours that signal depressions.
If you have a few known depressions---on the ground---that you can measure corresponding contour lengths for in your GUI, you could establish a quick and dirty rule just for the sake of testing the concept.
Comment: If you would like to think about this further, I would suggest converting all contour lines to *polygons* and studying the structure of their inclusions. A depression contour is one whose polygon is included within the polygon of a contour having higher elevation. (This is a simple, rigorous, correct characterization.) There are various ways to make this characterization operational, such as (the inefficient but easy one of) performing all pairwise comparisons of the polygons.
Comment: The shortest contour lines will, in general, mark *peaks*.  Looking at length also risks including pieces of contour lines typically found near edges and corners of maps. Another disadvantage of using length is that contours in rugged regions will tend to have longer measured lengths than contours covering the same areas in less rugged regions.  All in all, selecting depression contour lines based on length does not seem a promising approach.
Comment: Ah. I suspected this question might not get any attention so I wanted to offer the one thought I had. I know for sure I've seen depressions visualized on topo maps using hashes against the contours, so I thought a lengths comparison might work. Thanks for providing these contrasting insights.
Comment: Thanks for your reply and you approach.
At the moment, my idea is to find all contour lines without a smaller neighbor on the right-side(inside the contour line), but I have same problems to detect them . I know there is a possibility in Arcgis Desktop Advanced (Polygon Neighbors (Analysis) ).
Comment: Just been thinking about whubers answer, I bet you get some wacky topology. I was just thinking of the scenario of a volcanic caldera such as [Mount Teide](http://en.wikipedia.org/wiki/Mount_Teide) where the rim is higher, drops down to a plateau then peaks again with the central cone. So you have a peak inside a depression contour! Just thinking aloud...

Finding depression with contour lines


Can you use the actual sink to route an undermount sink hole in a butcher block counter?

Question: I plan to install an undermount sink in a new butch block counter top that is 1 1/8" thick. In order to cut the sink hole, could I simply attach the undermount sink to the counter in the correct position, then use a router with a bottom bearing flush trim bit (1 1/4" carbide) to cut the sink, with the bearing running along the inside of the attached sink? I have read about the method of creating a template out of plywood, but this method seems like it would be easier and more accurate. Is there something I am not thinking about?
Answer: Putting a bearing against a sink surface seems to be looking for trouble. The slightest resistance in the bearing could tear up the finish of the sink, whether it is porcelain, fireclay, steel or resin.
I think it's worth the trouble to make a plywood template, unless you are in the sink business and have spare units to burn.
Comment: The other reasons for templates is that you can either allow more easily for the extra clearance required for the fit. Wood can shrink and grow by relatively large increments compared to the sink.


Copy contents from an field entity reference

Question: I have 2 content type

1-Parent Product
Title
Fabric Type
Product Type
Product Description

2-Child Product
ParentProduct (Node Reference to Parent Product Content Type)
Title
Fabric Type
Product Type
Product Description
Product Code
Product Size
Product Color

Here is the use case.
1-I Create all my Parent Product

2-I Create a child
The first field I need to filled is ParentProduct (Node Reference)
By choosing the ParentProduct, I would like  this parent act as the default value for Title, Fabric Type, Product Type and Product description of this child.

Is there any module that could help me for that?

Thanks a lot
Answer: Using Entityreference prepopulate and Entityreference prepopulate token
Once installed, you will need to create a link for the Child on the Parent page's template that includes tokens for the fields you want prepopulated. The answer here shows how to string multiple values together.
If it needs use a Node Reference rather than an Entity Reference, then Node Reference URL Widget and Prepopluate will do approximately the same thing.


Describing a large scale battle in a science fiction/fantasy novel

Question: In my novel, there is a large scale battle involving several factions, tens of thousands of fighters, and is a defining part of the book, as it lasts for a good deal of the novel. As I wrote it, I tried to paint a clear picture for readers, but I found it difficult to decide how. How in depth should it be described (General descriptions such as simply stating that many fighters died, or describing in depth the specific experiences of the fighters and leaders)? Is there anything specific that should be avoided that could bore readers? If this question is to broad, I will edit it.
Comment: Read battle scenes in a lot of other books and see what they do. I like Mercdes Lackey's battle scenes because she brings in a lot of tactics, not just hack-and-bash.
Answer: I agree with Lauren Ipsum, byt read from a variety of authors, not just one. In addition, read The Art of war. I know I just gave you more homework, but if you know what each side's strategies are, you could establish that for the reader, then twist things up.
I'd also recommend reading the Illiad (or at least the battle scenes). Homer does what you do--says that this dude got stabbed through with a spear, and then "the darkness" fell over his eyes.
In any rate, try to have emotions. In the sense that you could zoom in on a few soldiers and their emotional connections with each other. Soldier A is friends with soldier B. Soldier B hates soldier C, so they both try to kill more enemies than soldier C, and they're having a grand time until Soldier A dies, and then soldier B is enraged and starts killing off everyone.
If you take the time to include little vignettes such as these, the fighting will seem more personal/visceral, since it's not just two random armies going at each other, but people fighting people.
Think of the battle of Helm's Deep in the Two Towers--Legolas and Gimli have a contest to see who could kill more orcs--this provides comic relief, and humanizes their army. Aragorn fights to avenge a dead friend--this further humanizes their army.
Humanizing both sides would be harder. Think how much longer LOTR would have been if Tolkien had introduced a bunch of sympathetic Orc characters who were hunting for the ring--not to mention how this would muddle the narrative. If all of you MC's are on one side, focus on the specific experiences of their side.
So in conclusion, focus on specific experiences--it makes the battle more real, and is more engaging to the reader overall. I hope this helped.
Comment: +1 (also for) The Illiad, which was my immediate thought for a reply. I add that Homer not only describes the battle actions in (poetic?) detail, he also makes mini-character descriptions. Many times there is a short description. Say: John Doe, with the bright eyes, youngest son o king Smith the second, from the beautiful plains of Some Land, was killed - this and that way - by (etc., etc.). That is, all characters are real people, not random soldiers, they ALL are HEROES, even if their whole appearance is only a handful of lines long.
Answer: I recommend that you look into military theory and historical examples. The subject is larger than life, so well chosen indeed.
Some pointers:

The Art of War by Sun Tzu
The Project Gutenberg version with commentaries included. May sound outdated but it is still being studied today.
Thermopylae
Some few battle pundits shaming the biggest army the world then knew.
Gaius Julius Caesar's Commentaries on the Gallic War
A whole series of battles and the biggest personal marketing campaign of the time.
Waterloo
This battle could have gone two ways until the French elite Imperial Guard faltered in heavy crossfire, and broke Napoleon's career.
Charge of the Light Brigade
Just one unwise tactical move but still a great example of an epic battle scene.

Pretty random list. There is a whole lot more to discover if you are so inclined.


Why must the entire chain be included in calculations if it's already been validated. Why can't the validated portions be archived to save energy?

Question: I'm new to this so don't laugh.  If all of the previous transactions in a blockchain have been validated as authentic, why does the entire chain have to be carried forward in the calculations?  Why can't the validated portions be hashed and archived to save energy costs from handling so much historical data.  When accountants calculate the current years income, they don't go back to when the company started and add up every income and expense item, they just add the current years results to the archived past totals.  What am I missing.
Answer: There is no difference between those two things. If you have a data set that includes only things that you have fully validated all of and you confirm that something is in that data set, you have fully validated all of it. So checking that it's in a data set of things you have validated cannot be done instead of validating the entire chain because it does validate the entire chain.
I'm not sure what you mean by "archived to save energy". If they aren't archived, they're stored. If they are archived, they're stored. So I'm not sure how energy would be saved.
Answer: Perhaps more a clarification than an answer: there is absolutely no need for validating nodes to keep a copy of the full historical blockchain around, and it's unnecessary to have access to the chain's data for validation. Storing the block data or not is pretty much irrelevant for energy usage.
In Bitcoin Core (a fully-validating node that's often considered a reference implementation), there is a possibility of running in "pruned" mode, where all blocks are downloaded and fully validated, one by one, but deleted from disk afterwards. This is possible because the full block data is actually not necessary for validating future full blocks; only the set of unspent transaction outputs created by that block need to be retained. This is done in a separate database that is only a few GB in size, compared to a few 100 GB for the full blockchain.
The only impact this pruning mode has is not being able to scan for historical transactions (e.g. you can't import an old wallet because it won't be able to find those old transactions), and being unable to provide the historical blockchain to new nodes that are still synchronizing (which they need, even if they'll eventually prune that data away too).
Answer:
When accountants calculate the current years income, they don't go back to when the company started and add up every income and expense item, they just add the current years results to the archived past totals. What am I missing.

The accountants won't start from the beginning, because they will have already done all of those calculations in previous years. This is similar to the function of a bitcoin node: it will not recompute the whole history to validate each new block, it will just validate each block once, and then store the network state, so that it can validate future blocks against that state.
The bottom line is, if you want to independently validate the history of the network, then you need to start from the beginning. Any other method will involve trusting that someone has supplied you with a legitimate intermediate state for you to begin your calculations from.
Note that a full node validating the chain is different than a miner working on finding new blocks. When people talk about the energy use of the bitcoin network, they are usually referring to the energy consumed by miners, not nodes.


Generate Mach-O binary from running process

Question: I have a packed executable. To take care of the unpacking, I would like to extract the in-memory version of the process, which would ideally be rolled back into the equivalent Mach-O binary -- such that it can be viewed in a disassembler -- I do not need the unpacked file to be runnable.
A Windows version of the same program exists, and it is also packed. Utilities such as PE Tool make this task simple: you select the process, then the module, and then you have an unpacked binary.
I am not able find any applications that can do this on the OS X side. I can imagine two broad approaches with runtime in mind:

the automatic way PE Tool can generate a binary when given a process and a module
attempting to roll a generic memory dump into the correct Mach-O file of the program's main module

I would appreciate any advice on either of these points. I have an OS X environment at my disposal though I am not familiar with it.
Advice relating to solving this problem through static analysis would also be appreciated
Answer: You can get some ideas from the dumpdecrypted tool by Stefan Esser. It's for iPhone but shouldn't be too difficult to port to OS X.


Who was Rabi Tanchuma?

Question: Was there an actual person Rabi Tanchuma attributed to writing the medrash that goes by this name? Do know anything about him?
Comment: http://en.wikipedia.org/wiki/Tanchuma
Comment: This question does not show any research effort.
Comment: @Double ^^^^^^^ continuing our conversation from the other day. Please let me know that you are aware of this as a Mod.
Answer: See this other  Wikipedia entry that states:

Tanhuma bar Abba (Hebrew: תנחומא בר אבא) was a Jewish amora of the 5th
  generation, one of the foremost haggadists of his time. He was a pupil
  of Ḥuna bar Abin (Num. R. iii.; Gen. R. xli.), from whom he transmits
  halakic (Yer. Ḥal. 57d; Shab. 10c) as well as haggadic sayings (Yer.
  Pe'ah 15b; Shab. 11d; Ab. Zarah 43a). He received instruction also
  from Judah ben Shalom (Midr. Teh. to Ps. cxix. 2) and R. Phinehas
  (Yer. Sheḳ. 49d). According to W. Bacher, he resided in Nave, a town
  in Peræa (comp. A. Neubauer, G. T. p. 23).

Midrash Tanhuma was named after him because he was the first person named in that Midrash, but, the Midrash itself was written during the course of many years. This is common, like Avot D'Rav Nattan which was named after him for a similar reason.
Comment: These wiki entries don't answer why we should assume the person mentioned in the medrash is the same person in the gemara. Or why to assume the entire work wasn't written entirely by him. Also the other entry from user7032 is based of information from encyclopedia judaica. I have have nothing against scholarly secular  research as long as it has moral integrity. I don't concider information from an overtly antireligious work especially believable.
Comment: @user6591 - I generally take wikipedia entries loosely. However, part of the question asks more generally about Rabbi Tanhuma, and it makes reference to the Gemarrah that he was an Aggadist, which does collude with what the Gemarrah reference mentions. Granted, it doesn't completely or thoroughly answer the question, but it does cover what we know about Rabbi Tanhuma, in general - again a part of the OPs question.

Who was Rabi Tanchuma?


Why is the Army Camp showing more troops then I have?

Question: I am new to Clash of Clans.  My problem is when I try to create new troops it stops producing because my camp is full.   But my camp capacity is 65, and I have created only 33 troops.  One thing to mention:  this amount is decreasing when I come back from an attack.  Can anyone tell me where the problem is?
Answer: According to the wiki, Giants use 5 housing space each.  You have 8 Giants which use 40 housing space plus 25 troops that use 1 housing space each.
8*5 + (5 + 11 + 9) * 1 = 40 + 25 = 65
Comment: Yeah, each troop has a set Housing Space they occupy, which can be checked by going under you're barracks and tapping/clicking the blue "i" by the troop icon.


Why won't this work? Dynamic in a Select

Question: Ok, I do this:
Select[Range[1, 20], # > Dynamic[q] &]

And then I create the slider:
Slider[Dynamic[q], {1, 20}]

And it'll always return an empty set! Why!
Update
The goal of this is to have the set change as I move the slider.
Answer: The key is to
remember that Dynamic does not control anything about evaluation directly. What it does is to create a spot on the screen which has evaluation properties.
If, for example, you were to evaluate the following in a fresh Mathematica
session...
b=5;
Dynamic[a=b];
b=6;
Print[a];

...then what will be printed?  Instead of evaluating it immediately, think about
it before you try it.  Hint...it's a trick question, but understanding the trick
will open your mind to exactly what Dynamic is doing.
The answer, which I will not reveal here (because you should really try it for
yourself!) can be explained by the fact that the Dynamic never did anything
because it never showed up onscreen.  The semicolon inhibited the onscreen
appearance of Dynamic, and without appearing onscreen, the evaluation of Dynamic
accomplishes nothing.
More subtly, if you remove all of the semicolons, the Print[] statement (at
least on my machine) still remains unchanged, but now for a completely
different reason.  That's because the onscreen placement of a Dynamic guarantees
that its contents will be evaluated, but not when they'll be evaluated. My
example sets up a race condition which, at least on my machine in v7, the
Shift+Enter evaluation wins.
To go back to your example,
Select[Range[1, 20], # > Dynamic[q] &]

This doesn't work the way you think it does because the Dynamic in this case
isn't evaluating to something which is displayed onscreen.
You could trivially demonstrate the result by doing...
Dynamic[Select[Range[1, 20], # > q &]]

but I'll assume you weren't just interested in displaying it on the screen, but
in setting some kind of side effect.  Perhaps you were assigning Select to a variable.
There are two ways to make these side effects happen.  One is to put them in the
second argument of Dynamic.  For example...
findset[x_] := (myset = Select[Range[1, 20], # > x &])
Slider[Dynamic[q, (q=#; myset = findset[q])&], {1, 20}]

The second is to produce a Dynamic which does have an onscreen appearance, but one
which is not noticeable.  For example,
Row[{
    Slider[Dynamic[q], {1, 20}],
    Dynamic[myset = Select[Range[1, 20], # > q &]; ""]
}]

In this case, the Dynamic actually is displaying.  It displays right next to the
Slider.  But you don't see it because what it's displaying is an empty string.
Nonetheless, it has all of the automatic updating properties that any Dynamic has.
For more information, you should read the beginning and advanced Dynamic tutorials
in the Mathematica documentation.  You can also see my post on comp.soft-sys.math.mathematica here (which I partly reformulated for this response).
Answer: I think you want to leave "Dynamic" out of the select.  This seems to work when I play with it:
In[20]:= x = 5

Out[20]= 5

In[21]:= Slider[Dynamic[x], {1, 20}]

Out[21]= \!\(\*
SliderBox[Dynamic[$CellContext`x], {1, 20}]\)

In[26]:= (*manually move the slider a bit to the right *)

In[23]:= x

Out[23]= 9.36

In[24]:= Select[Range[1, 20], # > x &]

Out[24]= {10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}

x = 2 (*slider moves left when I set this*)

Out[25]= 2

EDIT:  Your actual question was, "why doesn't this work" instead of "how do I get this to work".  Here's the problem:
In[12]:= q = 3

Out[12]= 3

In[13]:= (# > q) &[10]

Out[13]= True

In[14]:= (# > Dynamic[q]) &[10]

(* what you see on the screen looks like an evaluation that is held or something *)
Out[14] = 10 > 3

(* but the full form, which is conveniently what gets copied to the clipboard for
   pasting into this answer, is actually this! *)
Out[14]= 10 > \!\(\*
DynamicBox[ToBoxes[$CellContext`q, StandardForm],
ImageSizeCache->{7., {1., 8.}}]\)

So if you say 'Dynamic[1]' you do get a '3' on the screen, but it's not really a '3' -- it's some kind of notebook element that actually displays a '3'.
The result of the comparison function is an expression like the above, which does not evaluate to True, so select does not accept any elements, so you get an empty set.
Comment: Well, you are setting x to 3, without using the slider, and rejoice because the slider moves. Now, that might be interesting, but the goal, or hope, of my experimentation was to change the SET, as I slide the slider.
Comment: If you re-evaluate the Select statement, without the 'Dynamic' in it, then you do get a new set.  If you want the set to change all by itself ... I don't know!
Answer: You want the entirety of the initial Select expression to be dynamic, because you want to update the selected subset whenever the value of q changes. You can do this by moving the Dynamic outside. Try this:
Slider[Dynamic[q], {1, 20}]

Dynamic[Select[Range[1, 20], # > q &]]


Hydraulic brakes accidentally oiled

Question: Please help me. When I'm using my hydraulic brake I hear a weird sound. I think putting oil on it will cure the problem but I guess it just come out worse. After putting oil my brakes they are not working. How can I fix this?
Comment: If you think you have screwed up with your brakes, then the safest way to proceed is to find a qualified bicycle mechanic to fix it for you. The brakes is the area where you do not really want to learn by trial and error.
Answer: Braking surfaces (pads, rims, rotors) must never be lubricated in any way. Doing so can severely affect braking performance and is dangerous.
You can clean the rotor with isopropyl alcohol or mineral spirits.
The pads will probably have to be replaced as oil permeates into the pad material. You might be able to save them by cleaning with alcohol and sanding off the top layer, but replacement is the safest option.
Answer: You can read through this guide to clean your disc brakes How to clean disk brakes?.
Never put anything on your braking surfaces, that includes your fingers. Beside oils and acid from your skin, you can burn yourself.
If you are getting noises from braking, you need to start looking at the brake alignment, contaminants and loose axles.
In your case, you will need to carefully clean out the calipers to as the oil would have transferred in there.

Hydraulic brakes accidentally oiled


How to make a camera follow a specific particle

Question: I have been tasked with having a camera follow a specific piece of paper as it moves through an office environment. The paper is one of many that are flowing along and the shot is from the view of this one piece of paper. I know I can hand animate it, but I was wondering if there is a way to track the camera to a particle and see from it's POV (so to speak).  I would like to attach to the particle and look from it as if the camera were riding on the paper.
Comment: Do you want the camera to track the particle (look at it)? Or look from the particle (attach to it)?
Answer: I opted to manually animate the camera and keep a single particle object (piece of paper) in the field of view. Thanks
Answer:
Have one piece of paper not a particle.  This item is special and follows a path. Use the follow path constraint.
You might consider baking a one particle  .. particle system.  Total 2 particle systems.
The camera can follow the path as well thus following the paper as well.
The other pieces of paper remain as particles.


using rpccookiefile instead of username and password for antminers

Question: I mine using username and password at the moment but as bitcoin core is changing over to rpccookiefile. My question is, if i use rpccookiefile how do i point my antminers to my local bitcoind 'pool' as the fields on the antminers require username and password ?
Answer: The RPC cookie file is only for local authentication of bitcoin-cli.
For external applications, you should use rpcauth= lines in bitcoin.conf. A tool for generating these lines given a username and password is in the repository.


Did Aristotle write his works?

Question: I've heard that things like "ethics" and "politics" are not actual books written by Aristotle, but are instead manuscripts of notes of lectures he gave. Is this true for all, some, or none of his works? Were any destroyed and lost permanently? Do we know he was a real person?
Comment: You can see [Aristotle's Life](http://plato.stanford.edu/entries/aristotle/#AriLif) and [The Aristotelian Corpus](http://plato.stanford.edu/entries/aristotle/#AriCorChaPriDiv) for basic informations.
Comment: One of the weirder features about Aristotle's text that should be included is that another writer in antiquity after Aristotle wrote that Aristotle is a beautiful writer whereas what we have is not all that beautiful (in terms of the writing). (I'm not finding the reference right now for who).
Comment: Could I know on what materials Aristotle or his students wrote "his works"? Were those "works" wrote on paper, on papyrus, or on tablet made by mud?
Answer: According to Jonathan Barnes, in his book Aristotle, one of Aristotle's ancient biographers remarks that "he wrote a large number of books which I have thought it appropriate to list because of his excellence in every field": there follows a list of 150 books.  Curiously, the list does not include all of Aristotle's works.  Indeed, it does not include his two most highly regarded works - Metaphysics and Nicomachean Ethics.  Of all of the listed works, barely one-fifth (approx. 30) have survived.
Again, according to Barnes, most of the surviving works were peharps not intended to be read; it seems likely that the works that survive are made up of Aristotle's own lecture notes and not intended for public dissemination.  The two works cited above, Metaphysics and Nicomachean Ethics, appear to be put together by later editors.  According to Barnes, Nicomachean Ethics is evidently not a unitary work, and Metaphysics is "plainly" a set of essays rather than a continuous work.
Barnes supports his claims by noting that Aristotle's works are, for the most part, terse.  "His arguments are consise.  There are abrupt transitions, inelegant repetitions, and obscure allusions. Paragraphs of continuous exposition are set amongst staccato jottings. The language is spare and sinewy."  These features strongly suggest the lecture notes interpretation.
Comment: Barnes also wrote in his *Companion to Aristotle* pp. 10-11: "What did Andronicus [of Rhodes, 1st cen. B.C. editor of Aristotle's MSS,] do? How did his edition – how does our edition – differ from what Aristotle actually wrote? The answer, roughly put, is probably this: Andronicus himself composed the works which we now read."
Answer: First, Aristotle was a historical person. He lived 384-322 BCE in Greece. He is from Macedonia and went to Athens to start studying with Plato. Aristotle later founded his own school in Athens, the Peripatos. We have enough information about Aristotle to write a biography.
Secondly, Aristotle published two kind of works: Scripts for his students and for his lectures on one hand. On the other hand, dialogues and writings for the public, i.e. for intellectuals who were not formal members of his school.
Most part of the former writings are conserved, but nothing of the latter type of his writings.
Comment: @Nelson Alexander Curiously the fate of Plato's writings is just opposite: Plato's writings for his students (the esoteric writings) are lost. In both cases, we do not know why one part of the writings survived and the other not. - The writings of Aristotle were collected, selected and edited by Andronikos at about 40 BCE. Andronikos was at this time head of the Peripatos. The title *Metaphysics* is also due to Andronikos. The title simply indicates that Andronikos arranged these writings "behind" the books on physics.
Comment: Perhaps I should ask this as a question, but do you happen to know why, in contrast to Plato, his lecture notes survived, but not his dialogues? The latter would arguably be more plentiful and dispersed. Was it simply archival chance... or have any reasons been proposed?
Comment: Ref: Protrepticus. a reconstruction of Aristotle's lost dialogue by D. S. Hutchinson and Monte Ransome Johnson (2015),  http://www.protrepticus.info/
Comment: @Evan Adler- Aristotle's writings were lost after the fall of Rome. They did not reappear until Averroes, an Arab scholar who lived in Spain, translated the collection he owned from Arabic into Latin. It has always been difficult to assign any authenticity to any of those writings. An Aristotealian scholar I studied with claimed that Aristotle's collected works were not authenticated until the 1880s. Not sure if this helps or not. Regards,
Answer: Aristotle was both a Lecturer and Writer. The vast majority of Aristotle's works that have survived over the centuries, are voluminous collections of his lectures.  It is also possible-(and I believe very likely), that SOME of his lectures may have been the researched writings of his students at The Lyceum.  While Aristotle certainly deserves credit for having advanced Philosophy and Analytical Thought within Ancient Greece-(and beyond), I am not so sure that he alone, lectured on EVERY topic and subject within his voluminous collection.
Aristotle was also a prolific Writer, unfortunately all of (or nearly all of) his writings have been lost for more than 1500 years

Did Aristotle write his works?


Alkali metal hydrides

Question: I know that stability of alkali metal hydrides decreases down the group,Hence the lowest member in the group easily breaks into its cation but does this easiness of breaking into cation has any relation with its reducing nature.I also wanted to know what is order of reducing character in alkali metal group?
Answer: Alkali metal hydrides can typically be viewed as labile hydride anions. The extent of lability can correlate with the electronegativity of the metal. Hence, less electronegative metals in alkali metal hydrides yield more labile hydride anions and more "reducing" nature.

Alkali metal hydrides


Second-hand alpine skiing equipment

Question: I'm a beginner skier and I want to buy a complete second hand equipment. Could you please tell me what to look for when choosing such an equipment to be sure that I get a still usable one?
Comment: I tried to be as clear as possible and to avoid asking for shopping recommendation. I did not asked for a store list or anything alike. I asked what to look for in terms of features, not brands, and not where to look for. In case I buy a second-hand equipment what are the things that I need to look for to be sure that the equipment is still usable? What are the common areas where ski equipment breaks?
Comment: I added the "maintenance" tag. From my perspective, it looks like a recommendation for specifically you, but thanks for clarifying that you are looking for a guideline as to how to choose second-hand equipment for beginners.
Comment: Yep, that's exactly what I wanted.
Answer: As a beginner skier, I would recommend renting your equipment, particularly skis until you find the type and length you feel comfortable with.
You would want to start with a shorter ski until you feel comfortable with that length - nothing can deter a beginning skier faster that skis that are too long for them.
Once you are in a position to buy, many manufacturers offer 'demo days' where you can try out their different skis at no charge.
If you have progressed to a point where you're looking to buy, I would recommend starting with boots first as getting a proper fit can be difficult and most reputable ski shops will work with you to get the proper fit.
It wasn't until I started skiing that I found out I had flat feet, skiing for any length of time was extremely painful for me and I had to get orthotics for my feet. The shop that I purchased them from spent many hours shaving and trimming them until I was comfortable.
We always considered our boots the most important part of our equipment, when we flew somewhere new to ski, the boots always were 'carried on' the plane...if they lost your skis you could always rent another pair, but losing boots could be a disaster!

Second-hand alpine skiing equipment


Identity Verification for Remote Usability Testing

Question: Is there anyone out there who has to do identity verification for remote testing?  I obviously have to get the participants to sign an NDA but my legal department wants me to take it a step further and to verify the participants identity.  If you do have to do identity verification what do you do? I probably have to go with something that is free or costs next to nothing if I use a service. The only way that I can think to do it for free is to have them send me an image of their ID (driver's license, military ID, etc) or just show it to me before we start the test.  I'm not sure legal will go for that though so options to present to them would be nice.  The questions I'm coming across on this site are more focused with verification of credit cards or email addresses. Thanks for any input.
Comment: @MattObee: I'm sorry, that probably wan't very clear. Of course they'll accept an ID, but I don't know if they would appreciate the person just showing it to me through the webcam. I suspect they'll want a record of it other than a video that's floating around out there.
Comment: A sub-optimal solution to this is to avoid letting legal know about this stuff.
Comment: Also do make sure that the user knows before hand that they will be needing identification and signing an NDA. This will save your time and theirs.
Comment: If you don't think the legal department would accept photo ID, have you asked them what they _would_ accept?
Comment: I suppose I could take a screenshot, print it out and put it in with the rest of the files but if there's a more streamlined option out there I wouldn't be too upset :)
Answer: I have taken courses on Coursera that require you to have a web cam so you can hold up your photo id (at least the first time) and then have you let the software take your picture again during each session.
Let them know ahead of time, also let them know when their personally identifiable information will be destroyed etc.
I think it was Coursera that also requires you to type in a pass phrase, and it measures your typing response time based on the idea that it is "as unique as a fingerprint" but that might be going overboard in your case.
I have also done user testing with a large course management system company where I signed an NDA, and the testing was simply done while I was on the phone with them.
Comment: In the last course I took, the only verification they used was the typing fingerprint method.
Answer: Haven't done this myself, but have participated in things that have required this. Typically it just requires sending over a photo of an ID, meaning anything government issued. Legally, that's enough. Again, you'll face all liability, and it's not really an issue for someone to get a fake ID, so if you don't have a way to check against a government database, it's only a deterrent, and a slight one at that.


On the Idea of Progress

Question: Any suggested reading on the Idea of Progress? I am thinking of the idea that sprung within the West and during the Enlightenment, that promoted the belief that humanity (or at least parts of it) are in a constant, albeit intermittent, path to betterment. This idea does not seem to exist before this time or outside the bounds of the West.
Comment: You can see [The idea of scientific progress in Antiquity and the Middle Ages](https://pdfs.semanticscholar.org/8a77/4b796bf5dce90049029cdc0ec9a60fdaacd7.pdf) and L.Edelstein, [The idea of progress in classical antiquity](https://archive.org/details/ideaofprogressin00edel) and E.R.Dodds, [The Ancient Concept of Progress and Other Essays](https://books.google.it/books?id=sJflUnZFResC&printsec=frontcover).
Comment: That betterment brought people closed to monkeys. Proved Darwin's theory but in reverse. What progress do you mean ? Science is at a scam-halt, general products are of the lowest quality ever recorded in history and humans are more sick than ever.
Comment: The so-called neo-Thomists were contra this line of thought. E.g J. Maritain. We can probably add Alasdair Macintyre too. || Also anti-modern were Heidegger and Gadamer (though not to the extent of Heidegger). In France, at least Derrida. ||  On the side of the Enlightenment project, Habermas. Good book:  Title: The philosophical discourse of modernity : twelve lectures Author: Habermas, Jürgen.  Publisher:MIT Press,Pub date:c1987.
Comment: We discussed cyclical history recently https://philosophy.stackexchange.com/questions/51998/pendulum-theory-cyclical-theory-in-philosophy Rome fell. China went through a phase of powerlessness. The world wars burned up much of the booty from colonialism. Progress as inevitable sounds like 'an end to boom and bust', expansion and contraction, development and destruction, seem to be inevitable parts of economies and social development. Progress is a historically-bound phenomena which could be unravelled by dystopias, war, or varied apocalypses. We may be modern trilobytes
Comment: @MauroALLEGRANZA Thanks! Very helpful links.
Answer: In Ancient Greece there were no term corresponding to the modern one for progress.
In spite of this, there are many ideas and beliefs that we must consider :

myths and conceptions regarding the Eternal return;
myth of Golden age,

both dissonant with the modern idea of progress.
But there were alsio the myth of Prometheus, which conveys the idea that man has risen and not fallen, stressing man's intellectual progress.
Comment: You call the Golden Age & Eternal return myths, but not progress..?
Comment: It has been argued that key to the Rennaissance was the idea that the great thinkers of antiquity could be corrected, and their great works surpassed. I read an analysis saying the average living standard in Rome before it fell was not matched until London in the 1720s, which puts the blios we call economic depressions into perspective. For more than a millennia the great ruins of the past showed people progress was backwards. And now, the way frame economics we can't really imagine permanent falls, not recessions but collapse, though it may be inevitable for a range of reasons..
Answer: There is an unsurveyable amount of writings on The Idea of progress, on progress in general or in some distinct area. Sweepingly, one may be tempted to assert that the West progresses uniformly ever since the antiquity even if the Dark Ages  appear definitely to be a period of regress (see. e.g. Ian Morris and his data).  A briefest overview is Reinhard Koselleck's "Progress" and "Decline'': An Appendix to the History of Two Concepts (Practice of Intell. Hist. p218-35). The Idea of Progress ed. by A. Burgen, P. McLaughlin, J. Mittelstrass (1997) is a collection of essays by notable contemporary authors.
A recent work by Daniel Špelda, Veritas filia temporis: The origins of the idea of scientific progress (Annals of Sci, 2016) proposed an original development which merits some attention and also provides  good references.
Comment: The Dark Ages is a name primarily about the lack of records, rather than of progress
Comment: @CriglCragl I wonder how much of such records were destroyed as part of the anti-catholic movements of the reformation, French Revolution and etc (particularly in terms of ransacked and burnt monastery libraries).
Comment: @Crigl Yes, it's just a name, they were able to do Feynman integrals, but we lack records of that. (Added a link to Morris & data).

On the Idea of Progress


Are there rules and guidelines anywhere for loot in D&D 5e?

Question: My players are used to playing RPG's on PC and love getting new weapons and loot. I can't really find much in the PHB or basic DM guide.
I have been using http://redkatart.com/treasure5e/treasureGen.php up until now but it seems to only give gold and gems, and I would like to be able to make custom shops with randomized inventories to add a little flavour to my towns.
Even just a run down of equipment milestones players tend to need by certain levels or explanation of the whole "masterwork" weapon systems would be fine. Just something so I don't give them the "Sword of 1000 Truths" at level 3 and accidentally ruin the balance of everything.
Comment: @TheForestAndTheTrees On the other hand, magic loot in 4e is merely functional rather than wonderful, so may not be interesting if they're in it for that "oooh, shiny" feel.
Comment: A couple of related questions: [Does the DM have to give me magical weapons?](http://rpg.stackexchange.com/questions/46376/does-the-dm-have-to-give-me-magical-weapons) and [Without a magic item economy, what is gold for?](http://rpg.stackexchange.com/questions/47604/without-a-magic-item-economy-what-is-gold-for) Those might help show why "equipment milestones" like 4e has aren't anticipated to be part of 5e's treasure system.
Answer: Unfortunately, we won't see these guidelines (unless part of them show up in the previews), until the DMG.
So I can state confidently, that these rules do not exist in official published materials.
For now that treasure generator looks like a pretty solid option.
With respect to creating your own shops, unfortunately, the economy is based around magic items being rare enough that they are incredibly hard to both purchase and sell, so I'm not sure we'll see a list of shop inventories in 5e. The best I can do there is that the starter set has some guidelines on what mundane items shops in Phandalin have.
With respect to recommended items per level, again this is advice we simply don't have. But it's worth noting that in general items we've seen don't have levels. That doesn't necessarily means they wouldn't be overpowered for certain characters and underpowered for others, it just means we haven't seen levels attached to them. We have seen +1 attached to weapons and armor, so certainly you wouldn't want to give a L1 character a +2 or +3 weapon/armor, but beyond that the guidelines are non-exisistant at this time.
Comment: The DMG has been out for a while, perhaps we can update this answer to include the rules from DMG?
Comment: @eirvandelden I second this - it's been *quite* some time now, and an updated answer would certainly be beneficial.


Import Data from 48 GB csv File to SQL Server

Question: I am importing huge data file of size around 48 gb using SQL Server default Import Tool. It keeps on executing fine for app. 13000000 Row insertions but after it the Task Fails with following error.
I cant open the csv as its damn huge neither can i move row by row in it and analyze the stats.
I am really confused how to handle this.
Comment: How about breaking the file into many  smaller ones?
Comment: Have you tried increasing the size of the column mentioned in the error message?
Answer: You can use powershell to fast import large CSV into sql server. This script High-Performance Techniques for Importing CSV to SQL Server using PowerShell - by Chrissy LeMaire (author of dbatools)
Below is the benchmark achieved :

5.35 million rows a minute for non-indexed tables and
4.35 million rows a minute for tables with clustered indexes.

The script even batches your import into 50K rows so that during import, it does not hog the memory.
Edit: ON SQL Server side -

Make sure you have proper recovery model set .. for such load, bulk recovery is best setting.
Autogrowth is set to proper MB and not Percent.
Both data and log files are provisioned big enough so there is minimal autogrowth events.
Do the import during non peak hours.
Follow best practices described in Data loading perf guide and or my answer.
Instant File Initialization is enabled and power setting is set to high perf.
Comment: Load it in a staging table and then merge it.
Comment: What if I need to do something like this but during peak hours (many time per hours)? My data is smaller like a 15 MB Excel file. Using it as a linked server seems slow (I would guess because Excel data is not indexed).


How to discern the key/tonic when they are key changes in song

Question: Song link

Taking this song as example,From the beginning of the song, I was thinking that it must be a Bm, since the songs also end in a Bm. But after looking up the score, it was actually written in D major. So, how do you recognize since the song also starts in Bm (the 6th scale degree of D as you can see in the numbered musical notation). Besides, there's also a #4, which is G#. Is it because of raising the G in B melodic minor? Or it's just little key change to A major? The song also ends in Bm. How can you know the composer's intention whether it's in minor or major since the song could be lingering a lot in minor and occasionally go back to the major key? In short, is it aurally possible to get the "real" key when dealing with such situation?
Comment: Does Chinese (?) notation distinguish between the major and minor keys that would share the same key signature in Western notation?
Comment: Some music is made to not have a tonal center or key too.
Comment: @Laurence the concepts are the same as western music. This is a version of numbered notations score, and the only accurate one, as compared to the original song I used as an example
Answer: If a piece is written In a particular key, it will have that particular key signature. It can't be helped that every major key has a relative minor, using the exact same notes - sometimes.
Purpose of a key sig. is to avoid having to write in each # or b as it would occur virtually every time - in Bm/D every C# and F# would need putting in with 'accidentals'.
In minor keys, there are sometimes (as hinted earlier) extra notes which need to get changed, and taking Bm, probably more often than not, A# will be found.
Some composers in the past (Debussi??) have actually used key sigs that look odd - in Bm for example, F#, C# A#, or bizarrely, in Dm, Bb and C#. Which, in reality wasn't be a bad idea. It just never caught on.
In any written music, listening to it will determine whether it's major or minor (or even modal), but a lot of pieces will sort of modulate in and out of the relatives quite naturally, so it could be said that a piece ostensibly in Bm has passages firmly in D major.
Sadly, the version you post isn't in standard Western manuscript form, and is therefore unintelligible to me, and I suspect, a lot of other posters. But, if the key sig. was indeed F# C#, that would not necessarily denote D major any more than Bm. Last (and often first) notes/harmonies are always a good clue. Bear in mind that with 2#, it could have been in E Dorian...


Does updating already well-ranked content hurt SEO?

Question: I have some 10 to 15 pages that rank well for certain keywords. These pages receive consistent traffic from Google. These pages are about a year old. I want to update these pages with additional text and internal links. Will such an update hurt SERPs?
Comment: technically, it could... it depends on how you append it. Is there enough additional content to warrant a seperate page?
Comment: I intend to add text that adds value to the existing content. The updates don't fit as new pages on their own.
Comment: It's hard to provide an answer with so many unknown elements. Back up what you have and do a test run to see how the new page ranks. If you don't get equally strong results, restore the original file.
Answer: Search engine results pages (SERPs) and your rankings on them are a function of: your efforts, other websites, what interests the searchers (both what is searched for in a particular query and what was searched for previously, by you and others), and which search engine is used.
Location and the default language play a role also, if you search for Kale does the search engine think you mean a species of cabbage, a person's name or a place. That can depend on where you are, or if a movie is trending.

Will such an update hurt SERPs?

It is likely to alter them, in a few weeks. Done correctly you will improve your ranking, done incorrectly you will fall. The exact formula each search provider uses is tweaked to provide what they believe to be the best results. While each offers general guidelines, and there are plenty of webpages offering advice, the exact formula is guarded to prevent abuse.
Think from the viewpoint of the searcher, when they search for a particular subject what results would they prefer to receive. Pages offering value to the reader ought to index correctly for the particular term chosen. Pages simply offering a word match, and a bunch of ADs, ought to rank lower.
Additional text that expands upon the subject with internal links leading to additional relevant information is likely to improve your ranking.
Additional text that repeats existing information and links leading to subjects far removed from related searches ought to lower your ranking.


What is the effect of energy drinks on the heart?

Question: I was watching a Youtube video of a man who supposedly drank 20 energy drinks in a row. It appears that his heart enlarged greatly. Is this something that energy drinks could actually do?
Comment: I assume my following question as related: https://medicalsciences.stackexchange.com/questions/20390/do-cardiologists-learn-nutrition-as-part-of-their-expertise-in-cardiology
Answer: In short, there seems to be no evidence that acute caffeine overdose by drinking a great amount of energy drink would result in heart enlargement (hypertrophic or dilated cardiomyopathy). It could cause severe caffeine overdose, though.
8 oz (237 ml) of an energy drink can contain 150 mg of caffeine (Mayo Clinic).
20 such drinks would give you 3,000 mg (3 g) of caffeine and 4.7 liters of water.
3 g of caffeine, does not seem to be lethal:

Lethal doses of caffeine have been reported at blood concentrations of
  80 to 100 micrograms/ml which can be reached with ingestion of
  approximately 10 grams or greater. (Stat Pearls, 2019)

4.7 liters of water drunk in a short time can result in fatal water intoxication. There is a report of a woman dying after drinking 4 liters of water in 2 hours.
Symptoms of caffeine overdose: How to recognize caffeine overdose (Nursing, 2019):

Moderate toxicity can cause restlessness, tremors, anxiety, mood
  changes, and gastrointestinal discomfort (such as vomiting). Very high
  doses of ingested caffeine (more than 6 mg/kg) can decrease both
  physical and cognitive performance and induce severe gastrointestinal
  distress. Extremely high blood levels (up to 150mg/kg) of caffeine
  can cause changes including hypokalemia, ventricular dysrhythmias,
  hypotension, rhabdomyolysis, and death. Blood caffeine concentrations
  around 150 mg/kg of body weight can be fatal.