What's the difference among the logical relations :=, =, and ≡?

Question: I understand that ≡ is logical equivalence, "iff". '=' is a symbol for numerical equivalence. And ':=' is an identity claim. I often only see '=' and ':=' used with variables and names, while ≡ only appears with predicates. I'm not sure if this is just from my limited exposure to logic or an actual convention. What's the big difference if we were to say 'a=b' vs 'a≡b'?. Or, for that matter, 'Px:=Qy'?
Comment: Can you give an example of := in usage?  I like others, have seen := used in programming languages, but I have not seen bare logic.  I'd love to see an example of it used in a document describing logic; I'd love to see the precursors to its use in programming.  For me, := has always been "assign a value/define" in programming only, = is "equal to" and ≡ is "same as" for situations where the word "equal" is not quite right.  I love symbology, so if there's a usage of := I've missed, I'd love to research it!
Comment: @CortAmmon - you can see it in Dirk van Dalen, [Logic and Structure](https://books.google.it/books?id=u0wlXPHATDcC&pg=PA58) (5th ed - 2013), page 58.
Answer: There is no strict universally accepted convention.
In mathematical logic, ≡ is logical equivalence, as you said, and it is a connective between proposition (in propositional calculus) or formulae (in predicate calculus).
Example :

(p → q) ≡ (¬p ∨ q).

Usually, = stands for equality and it is a binary relation between "objects", like numbers in arithmetic.
Example :

∀x (x+0 = x).

Finally, := is derived from programming languages, and is used (less often then the two above) as an "assignment" function : "let x be ...".
Example :

ψ := (x = y), stand for : let the formula ψ be (x = y).

Note : except for programming languages, := is not usually a symbol of the (object) language, but of the meta-language, while the two above are usually symbols of the language.
But we have to use = also in meta-language contexts, e.g. to express the identity relation between expressions; we can avoid confusion according to the context, but in some "pedantic" cases we introduce a different identity symbol for the meta-language, like ≐.
Comment: I've seen ≡ used for defining a variable, just like the same way we would use :=, in many books on mathematics...
Comment: Rather confusingly, some texts use ≡ for logical equivalence but many, particularly older ones, use it for material equivalence. That is a usage that goes all the way back to Principia Mathematica. Best just not to use it. I would suggest using ⊨⫤ or  ⫤ ⊨for logical equivalence and ↔ or ⊂⊃ for material equivalence.
Answer: It depends of context. But, usually

:= is to define a objects from anothers. Usually one define variables from values, x:=7, and maps, f(x):=x+1. Many programming languages use = to do that, but Pascal language uses := to assign values.
= is to compare two objects and ensure they have the same "identity". For instance, some programming languages use "==" to do that: a==b is true if previously we defined a:=2 and b:=2.
≡ have two interpretation. In logic it usually means "propositional equivalence", it a little subtlety; for instance, the existencial quantifier is "defined" $∃x P(x)≡¬∀ x P(x)$. Shortly, if a≡b you can put b where you see a, and vice versa.

Also, in algebra ≡ is the congrunce operator; for instance, a ≡ b mod n means a-b is multiple of n.


Arduino-RS232 converter baud rate problem

Question: i have built a TTL/RS232 converter to send strings via RS232 using an Arduino nano, following the tutorial:Arduino-RS232. My problem concerns the transmission baud rate, because in the tutorial it is suggested a short script which manually generates the code which will become the RS232 signal. In this script some constant delays are used, i.e. "bit9600Delay 100 " and so on. These delays are set for a baud rate of 9600, but i need to double it to have a baud of 19200. Is it enough to divide by two those constant values or should i use a different method? Thank you very much
Comment: Do you notice anything when you look at the 4800 baud values?
Comment: Dividing by two may not be the best option since bit4800 delay is 188 and bit9600 delay is 100.  Seems like the delay is mainly used for reading the bits that were sent over the RS-232 port.  So this wait time may be good to run at 19200 bps.  After all, it looks to me like it is a simple delay to allow enough time to read back data without having it being distorted (nonsense).
Answer: It is never good to base code on delays instead of intervals.  This is especially true for faster intervals where the execution of the code its self consume a significant portion of the interval.  Also note, some protocols only occasionally resynchronize.  RS232 resynchronizes after each byte (about 8 bits of data).  So any accumulated delay errors may impact the integrity of the bits furthest from the resynchronization event.
Instead of delays use the Arduino's built in hardware to send and receive RS232 communications.  The hardware is designed to work independently of code execution and will out perform software implementations especially for the faster baud rates.
Comment: The waters might be a bit muddy here.  I think the Arduino's delays are based on the number of ms passed (intervals of time).  So they might be somewhat immune to interrupts.  (That is to say, they may not be simply dumb loop counters.)  Still, the built in processor HW is a much better choice for RS 232 communications.  But, if you need a SW implemented RS 232 port, there are libraries which have already lamented over these problems of balancing code execution time against the necessary delays needed to generate the proper baud rate.
Comment: Yes, the normal `delay` is based on time. `delayMicroseconds` is a tight loop. This is partly because of the granularity of the timer used for `millis`, `micros` and `delay`.
Answer: This Arduino sketch is a wonderful opportunity for you to learn the very basics of serial communication.
You should be very careful scaling the constants given in any baud rate program (whether using a hardware or software UART) as they are normally off by some small percentage, and without understanding the implications you may eventually introduce timing errors.
There is a great description of the timing sensitivities in this Picaxe note.
The table below shows the actual bit times for various baud rates:

Notice here that for 9600 baud the sketch uses a constant which will use a 100 uS delay function for the bit times. From the table above you can see that this is slightly inaccurate, and the more correct delay would be 104 uS. This is an error of about 4%.
Would this error prevent successful reception of characters in the sketch?    Single characters with inter character spaces more than 1 character time, no ....but if you sent a string of characters end to end with no gaps this sketch would fail on receive.
Scaling the constant for 19200 baud --> 100/2 gives 50 but the bit time for 19200 is actually 52 uS, so again an error, this time of about 1%.
If we scaled the constant (100) for 115200 --> 100/12 gives 8.3 uS while 104/12 gives 8.7 uS for an error 4.5% or close to 0%.
There is IMO an error in this sketch for the serial receive routine, since it's hard wired to expect 2 stop bits. Any concatenated characters separated by only one stop bit will fail (you miss the second character start bit).
<code>int SWread()
{
  byte val = 0;
  while (digitalRead(rx));
  //wait for start bit
  if (digitalRead(rx) == LOW) {
    delayMicroseconds(halfBit9600Delay);
    for (int offset = 0; offset < 8; offset++) {
     delayMicroseconds(bit9600Delay);
     val |= digitalRead(rx) << offset;
    }
    //wait for stop bit + extra
    delayMicroseconds(bit9600Delay);     ....hard wired two stop bits
    delayMicroseconds(bit9600Delay);     ....or 1 stop and 1 bit time gap
    return val;
  }
}
</code>


Is sugar a thickening agent?

Question: Is sugar a thickening agent? Palm sugar for instance?
Let's say if sugar has a role in thickening liquid then how does it do it?
Answer: While sugar makes a liquid thicker, it is not considered a thickening agent.
Sugar is a crystal. When you add it to water, what you get is a simple solution. A solution of a solid in water is always thicker than water. This happens with all kinds of everyday substances. Whenever you add a thick liquid or a solid to a thin liquid, the result is a semi-thick liquid. The "thickening" here is roughly proportional. In that sense, you are not thickening the thin liquid, but creating a mixture whose thickness is the average of the thicknesses of its components.
A thickening agent, on the other hand, really thickens. It does not dissolve in liquid in the sense that it breaks down into ions swimming freely among the polar water molecules, but creates a hydrocolloid, also known as a "gel". This is a very special phase combination in which a few solid strands of matter trap lots of liquid in such a way that the liquid cannot flow easily. This results in a thick consistency.
Because a single molecule of a hydrocolloid building substance can trap lots of water, you can add little amounts of this stuff to create really thick liquids. Starch is added at a ratio of about 1:10 to create pudding, and some others such as xanthan can be used at ratios as low as 1:200 to create a creme and 1:1000 to create a milky-thick liquid out of water. At these consistencies, they rarely have consequences for flavor or nutrition, but really change the texture of your food. This is opposite to dissolving solids like sugar: if you wanted to add enough sugar to get your solution to a milky-thick consistency, you'd have an unbearably sweet liquid. For achieving a creme-like thickness, you actually need a supersaturated sugar solution, which is basically a candy (you'd have to stop heating somewhere below the soft ball stage).
So, while sugar does thicken somewhat, you will not use it for the purpose of thickening. If you were to choose the amount of sugar to add based on how thick you want your food, you will change all of its other properties, starting with making it overly sweet. The exception is when you are making candy: here, you are really using the thickening power of sugar, and you are controlling the amount of sugar such that you get the desired final consistency. Another exception is making jam - while it also has pectin together with the sugar, the amount of sugar is high enough that it also contributes a lot to consistency.
Comment: Generally true, although hydrocolloids *do* dissolve above the hydration point; they then crystallize again as it cools and that's when they start trapping all the water. At least that's how I understand it...
Comment: @Aaronut I think that the thermodynamic behavior of all hydrocolloids is much more complicated than simple dissolving. As I understand it, they disperse in the liquid, but don't form a true solution by breaking down into separate ions. But this is probably foo fine a distinction to make for the purposes of this answer.
Comment: Would you say that sugar and the method concentrating have a role in thickening the caramel sauce?
Comment: @mylifeisalie yes, sugar is thickening in caramel sauce. Anything whose bulk is sugar is thickened by the sugar too. Caramel is just a stage in the candy making process, and pure caramel consists of 100% sugar. You add fat and liquid to make the sauce, but normally enough sugar remains in it to thicken it.
Comment: I'd like to add that if you use starch for thickening, adding sugar is actually detrimental to the thickening effect. (Because the sugar creates a rivalry for the water molecules so to speak).
Answer: The viscosity of sucrose (sugar) solutions goes up quite rapidly as you increase its weight percentage over about 65%. Pure maple syrup runs about 60% sucrose.
Unless you're looking to make something horribly sweet, sugar does not make a good thickening agent.
Comment: Im making caramel sauce, but it didnt turn out well
Comment: Voted up for cool reference

Is sugar a thickening agent?


Who did Rita mean she tried having sex with?

Question: In Edge of Tomorrow, when Cage asks Rita if she's tried having sex to get the time loop ability back, with whom does she mean, since they are the only 2 who have had the ability?
Answer: I don't think we should interpret Rita's response to mean she tried using sex to get the ability back after she had lost it.
Instead, I think Rita tried to transfer the ability from herself to the person she was in love with during her cycle at Verdun. (i.e. while she still had the ability.)
She watched that person die ~300 times, and tried everything she could think of to save them and/or share her "gift" with them. Hence her strong conviction that Cage would not be able to give it back to her again (through any means).
Comment: Nice. I didn't make the connection between that scene and the lover she didn't want to talk about.
Answer: I think it's a mistake, made in the script and shouldn't be there because it's a ridiculous notion, if she still had it she wouldn't have tried having sex with anyone in the hope of getting it back, unless it was one of the aliens - or she might have tried passing it on, but in that case she hadn't lost it. right? so it's either her old boyfriend or an alien, don't think the alien would be so receptive though.
Comment: As the accepted answer points out, the asker got it wrong in the first place anyway, and it wasn't someone she tried to have sex with in order to get back the ability, but someone she tried to transfer it to when she still had it. So your answer seems quite irrelevant afterall, since this has never been in the script in the first place.


Does a cape need tzitzit?

Question: If someone wears a garment with four corners, it needs tzitzit. Now, a cape pretty clearly has four corners. However, it's not clear to me whether or not "wearing" it follows the halachic definition of wearing. A cape is (generally) worn by tying two of the corners around your neck, and letting the rest hang behind you. You know, Superman style.  In this manner, it doesn't provide any protection or cover you up at all. In fact, the only thing it seems to be good for is for looking cool while flying through the air.
Comment: Shaloman doesn't need a cape ;-)
Answer: EDIT: My initial reading of the shulchan aruch was wrong. According to the cited sources, a cape such as described in the question (a typical superhero cape), would not require tzitzit as it only has two corners at the bottom

According to the shulchan aruch (O.C. 10:7 and 10:8) a cape as you have described (open up front, and usualy tied up top) would require tzitzit:
From sefaria
Shulchan Arukh, Orach Chayyim 10:7:

מלבושים שהם פתוחים מן הצדדין למטה ויש להם ד' כנפות לצד מטה ולמעלה הם
  סתומים אם רובו סתום פטור ואם רובו פתוח חייב. ואם חציו סתום וחציו פתוח
  מטילין אותו לחומרא וחייב בציצית ואין יוצאין בו בשבת:
[Regarding] Garments which are open from the sides down and have four
  corners on the lower part but on the upper part they are closed: if
  the majority is closed they are exempt [from tzitzit] while if the
  majority is open they require tzitzit. And if half is open and half is
  closed one treats it stringently and it requires tzitzit, but one must
  not go out [in public domain] wearing it on the Sabbath.

and Shulchan Arukh, Orach Chayyim 10:8:

קאפ"ה שהיא פתוחה בענין שיש לה ד' כנפות אם יקבעו בה אשטרינג"ה לעשותה
  כסתומה כדי לפוטרה מציצית אינו מועיל תקון זה אם לא תהיה קבועה מחצי ארכה
  ולמטה לכל הפחות וגם שתהיה קבועה למטה מהחגור למען יהיה הרוב הסתום רוב
  הנראה לעינים דאם לא כן יאסר משום מראית העין:
A kapa[1] which is open, in a way in which it has four corners: if
  one has affixed astringa[2] to close it up in order to exempt it from
  tzitzit, it is ineffective unless it fastens for at least half the
  length and down to the bottom and should also be fastened below the
  belt in order that the majority should be closed, a majority that
  appears to the eyes; if not, it is forbidden because of marit ayin[3]

The primary distinction seems to be whether the garment is closed up front (generally called a cloak) or not majorly closed up front (generally called a cape). The latter fits into the description in your question.
Comment: you never tied a blanket around your neck and pretended to be super man when you were younger?
Comment: Sorry, but your reading if the SA is incorrect. It says specifically ***"and has four corners on the lower part*** but closed on the upper... " In this case, the cape has TWO corners on the lower part, and two tired together (closed) on the upper. No tzitzit here.
Comment: Oops, you seem to be correct. Apparantly my lack of experiences with actual capes made me not take notice of this partical detail in the text. Tbh, even though I accept your correction, I have difficulty imagining such a cape.
Comment: I still do that from time to time ;P. But indeed, most, if not all classic superhero capes would not need tzitzit, since the bottom only has two corners. Given that the kapa referred to here is ladino for a large type of cape/cloak similar to an overcoat, I guess that the four-corner types of kapa would be capes that have a deep split in the back? _also: do I need to add an edit to the answer to make clear that my first interpretation was in error?_

Does a cape need tzitzit?


My question was closed for being opinion based, but I submit that that isn't the case

Question: I asked a question about software design. It is on topic. I also read the questions to avoid, which was linked to in the Ask Question page. Now, the question was put on hold as primarily opinion based. I believe this question is helpful to many people. How should this be stated then? Does this question not fall under the exception Constructive Subjective Questions near the end?
Comment: ["We already tried supporting those questions, we even gave them their own site. Sadly, it didn't work out..."](http://meta.stackexchange.com/a/200144/165773)
Answer: Consider the following possible answers:

I don't think it's a hinderance. Knowing functional programming helps you understand various aspects of higher order functions that are finding themselves into many traditionally non-functional languages.

Having all these ideas spinning around in my head?  Yea, thats a problem.  I can't decide if I should use a map or a fold.  And then when I do use these, they get taken out in code review for being overly complex and unnecessary.

These are two fundamentally opposed answers that are equally right.

The question you end up asking:

Based on your experience, how would knowing multiple programming languages affect a software developer's (or your) ability to design programs?

is asking for anecdotes.  The question seems to be looking to foster a discussion and a telling of stories:

"Reason for the question (just a background; not part of the question. There is no need to discuss or explain this part unless you want to. I'm merely including this to shed light on why I asked my question above)".

Also, hidden within this is a career growth question, which also tends to foster opinions and anecdotes:

I'm sure many people would be interested to know the answer to this question. Software engineers would like to know if not being limited to one language would improve their design ability, programmers would be thinking ahead, managers would also want to know especially when it's time to choose someone they can trust to come up with a good architecture.

The bit about discussions comes up - the Q&A part of Stack Exchange is about questions that have answers.  From the tour:

This site is all about getting answers. It's not a discussion forum. There's no chit-chat.

I would suggest that you read On discussions and why they don't make good questions and Discuss this ${blog} (the later of which is particularly important with the passage "In my readings, I came across a proposition saying that good programmers don't make good software engineers because, it was said, good programmers know a programming language (and a framework or technology) very well, and that would make his designs somehow as constrained as his language."
So, to summarize:

There are too many, personal, answers to your questions - the question is seeking discussion or to poll people for opinions and anecdotes.
The question you are asking does fall the bullet points of what types of questions should I avoid asking:

there is no actual problem to be solved: "I'm curious if other people feel like I do."

Trying to get people to explain other people's opinions is also an opinion.
Comment: I see.. Ok, I have a clarificatory question, just so that I won't ask questions like this again in the future that might get downvoted and placed on hold again thereby possibly banning me from asking further.

1. When I asked if knowing multiple languages would be an asset or a hindrance, I thought there was one answer. That answer I wanted to know. What should I have done to figure out that it could be answered in two or three ways that are equally right?
Comment: 2. Does that mean that in the future, I cannot ask things like what algorithm to use for a particular problem? (because I bet there would be differences in expert opinion on that.) I was hoping to be able to ask questions like that here.
Comment: 3. I may be wrong, and correct me if i am, but when I asked that question, I really had a problem. My problem was I wanted to create better designs, and I don't know if that would be aided by knowing many languages. It's like, I wanted to sort a database efficiently, and I don't know if using this algorithm or another would get me there.
Comment: 4. Finally, I want to ask if I should not include background information in my future questions (like the way I did in this question) what I've read that led to my problem. I'm asking this because, like in this case, it got misinterpreted that I was asking people to discuss this ${blog}, which is totally not the case. I wasn't trying to get people to explain other people's opinion. It is as good as not there. I just included it for context. Should I not include things like that in the future?
Comment: Again, I'm asking these questions in the hope that I'll be a better contributor to the community in the future. I wouldn't be able to do that as well if I can't post a question anymore. I hope to avoid that. I've read the rules, but again, asking a question here isn't as trivial as it may seem at first. Reading the rules certainly is not enough.
Comment: Oh, wait.. P.S. to number 4.. (I can't edit the comment anymore. > 5mins..) The backgrounder info is as good as not there. In fact, the edit history would show that the original question did not include it. When the question was put on hold and downvoted, I thought it was because of lack of information, so I wrote that thing. It was not to discuss a blog or opinion. But apparently, it got misinterpreted to be that way. Sorry for the long series of comments. I just simply don't understand and if I continue w/o clearing this up, I'm afraid I'll end up with a lot of downvoted or closed questions.


What makes Hulk differentiate the enemy from the allies during the last fight in "The Avengers"?

Question: In the movie The Avengers how does HULK differentiate between the enemy and the allies? Previously when he turns into the beast aboard the avengers space craft, Hulk fights with Thor which means  that he does not know who is enemy and who is ally. But during the last fight Hulk smashes the aliens only. How? And what makes him differentiate the enemy from the allies?
Comment: Related (if not even duplicate): http://movies.stackexchange.com/q/2236/49.
Comment: No not satisfied.... still that differentiating element is missing
Comment: Well, if he's learned to control Hulk, he also learned to differentiate enemies from allies like all the other reasonably thinking Avengers (i.e. the evil looking aliens are the enemies).
Comment: During that whole war there was no military fighter planes which were sent by the defense . If Hulk encountered a fighter plane then what you think he would have thought about it ? enemy or ally?
Comment: Assuming *Banner* had gained complete control of *Hulk* (whichseems likely), he surely does know what to do, *Hulk* isn't a complete child devoid of any consciousness, he's just a wilder and more primitive version of *Banner*. And *Banner* certainly knows what a fighter jet is.
Comment: Well thanks Napoleon Wilson for clearing my doubt. lets see what all new things Hulk learns in Avengers 2: age of ultron
Answer: If you think of Banner and Hulk as 2 different entities, then the Hulk's main objective is to protect Banner from coming to any harm. This explains why he stops Banner from killing himself (this is mentioned in the Avengers).
It also makes sense that when Banner's heart rate gets too high the Hulk appears, it's his defense response kicking in. The same when he gets angry, it's the Hulk trying to attack whatever Banner is angry at.
We can assume in the time Banner was in hiding that he has learned to control the Hulk better, so that he can suppress him coming out or call him when he needs him. Apparently he does this by staying on the brink of anger all of the time.
However in a situation like when Hawkeye blows up the Helicarrier, the Hulk comes out because he perceives Banner to be in need of him (whether that's through loss of control, anger, heart rate is not explained).
So when the Hulk is released unbidden, he will generally smash anything and everything nearby, in that case Black Widow, because he is trying to protect Banner. This quickly gets sidetracked though as soon as Thor, and later the fighter jet, get involved.
If you ever notice in the films, the Hulk always attacks whoever or whatever is attacking him. He will stop attacking or chasing something if something else is being more aggressive or threatening (like the fighter jet).
In the battle of New York, however, Banner calls out the Hulk, so has more control over him. This is how it helps to distinguish who is a friend or foe.
So if a fighter jet just showed up, he probably wouldn't pay it much notice. But if it started shooting at him he probably would attack it just as soon as any of the aliens.
Comment: Superb man ... I had never thought of this "Hulk protecting Banner concept"..... Thanks....A lot......
Comment: `the Hulk always attacks whoever or whatever is attacking him` - This.  Black Widow's the most *apparent* threat mid-disaster (even if she never actually attacked him) when the Hulk first emerges, as well as being insulting to him (via fearing him).  Then Thor attacks, then the jet attacks, both, in turn, diverting his attention.


What was Spinoza's take on miracles: what are they are why think they do occur?

Question: What was Spinoza's take on miracles: what are they are why think they do occur? I'm asking because I want to find out and this could, conceivably, be the easiest way. I've read a chapter or two of something by him, and backed off because it seemed to work and didn't want to be brainwashed by 'God'. I was going to read about Hume's On Miracles but just got bogged down in something else.
Comment: See G.Hunter, [Spinoza on Miracles (2004)](https://www.jstor.org/stable/40034073?seq=1#page_scan_tab_contents).
Comment: See my answer which gives you confidence you're not getting brainwashed:  ( https://philosophy.stackexchange.com/questions/51173/fundamental-idea-on-proving-gods-existence-with-science/51175#51175 )
Comment: I don't think Spinoza believed in anything supernatural. He believed God is the natural universe, as far as I know. So I expect he would consider miracles as just *unexplained* and mysterious phenomena, rather than anything that would be completely impossible (i.e. supernatural).
Answer: See : Baruch Spinoza, Theological-Political Treatise (1670), Ch.6 : On miracles.

I will show:

(1) that nothing happens contrary to nature, but nature maintains an eternal, fixed and immutable order, and at the same time demonstrate what should be understood by the term 'miracle'
(2) that from miracles we cannot know about either the essence or the existence or the providence of God, but rather that all three are much better grasped from the fixed and unchangeable order of nature.
(3) I will show from some examples in the Bible that by the decrees, volitions
    and providence of God, Scripture itself means nothing other than the order of nature which necessarily follows from his eternal law.
(4) Finally, I will discuss the method required for [correctly] interpreting the
    miracles narrated in the Bible and what we should particularly notice in such miracle narratives. These are the chief points in the argument of this chapter, and I think that they are also very relevant to the aim of the work as a whole.

According to Spinoza, miracles are useful in producing veneration and in consolidating and maintaining political power :

The common people therefore call unusual works of nature miracles or works of God and do not want to know the natural causes of things, partly from devotion and partly from zeal to oppose those who pursue natural philosophy. [...] They also wanted to show that the whole of nature was directed by the governance of the God whom they adored solely for their own bene¢t. People have always been so drawn to this idea that to this day they have not ceased to invent miracles, in order to foment the belief that they are dearer to God than others and are the ultimate reason for God's creation and continual governance of all things.
Answer: Spinoza's position on miracles is captured in the following commentary offered by Warren Zev Harvey. I would not normally use an extended quotation but the issues are complex and can be compressed only up to a point. Maimonides* (1138-1204), as you probably know but I'll just add, was a Jewish philosopher and a very considerable influence on Jewish medieval philosophy and beyond.
DEUS SIVE NATURA
'God or Nature' is a phrase derivable from Ethica, IV Preface and Demonstration IV.4 (Deus, seu Naturam appellamus and Dei, sive Naturae [God, otherwise called Nature]. If you fear being 'brainwashed by 'God'', there's an easy precaution in the case of Spinoza. Whenever he writes 'God', except when quoting Scripture where he's stuck with the name, or when he uses the formula 'God or Nature', you can read 'Nature' instead of 'God'. There is a totality, an interconnected system, which we can refer to equally as God or Nature.

Spinoza begins his discussion "Of Miracles" with a typically Maimonidean*
   observation. Although the intelligent individual sees the presence of God in
   the fixed order of Nature, the multitude see God's presence in its supposed
   disruption or violation, especially when those imagined aberrations are to
   their benefit, and they call such allegedly supernatural phenomena "miracles." Maimonides had scoffed at the masses who believe that babies are
   supernaturally conceived by the work of a gigantic fiery angel who enters
   the mother's womb, while in fact the true "angels" responsible for birth are
   the nmatural biological forces.
Next Spinoza proposes a fascinating historical explanation for the origin of the belief in supernatural miracles. According to his conjecture, the
   belief in supernatural miracles was originally a polemical response to idolatry. The ancient Israelites saw that the pagans worshipped visible gods, such
   as the sun, the moon, the earth, or the air, and in order to prove that such
   gods were not truly powerful but dominated by the invisible God, they told
   stories about divine miracles interfering with their actions. In addition,
   notes Spinoza, these stories of supernatural miracles reinforced the fantasy
   of anthropocentrism.
Spinoza now announces that he intends to show four things: (I) nothing happens contrary to Nature, and the word "miracle" must be defined
   accordingly; (II) God is known not through miracles, but through the fixed
   order of Nature; (III) the will of God is nothing but the order of Nature; and
   (IV) biblical miracles should be interpreted in accordance with a particular
   method.
I. NOTHING IS CONTRARY TO NATURE
Since the laws of Nature are eternal divine decrees, Spinoza argues, their
   contravention would amount to the contravention of eternal divine decrees.
   As he puts it, it would amount to God's acting "against His own nature"
   and "nothing is more absurd."
   The word "miracle," according to Spinoza, designates a wondrous
   event that one is unable to explain by reason on the basis of the laws of
   Nature. Since all events, in theory, can be thus explained, a miracle is
   always relative to the opinions of the speaker or speakers (ad hominum
   opiniones). Thus, the prolongation of daylight at Gibeon was a miracle in
   the eyes of Joshua and the Israelites, but, had Spinoza been there, he would
   not have considered it as such.
II. GOD IS NOT KNOWN BY MIRACLES
It is clear, argues Spinoza, that God cannot be known through miracles.
   God is known only by means of "clear and distinct" premises, but miracles
   are events that are not understood and thus cannot be the basis of true
   knowledge. If anything, remarks Spinoza wryly, miracles, understood as
   contravening the laws of Nature, would lead one to doubt the existence of
   God. Belief in such miracles, he repeats, "would make us doubt everything
   and lead us to atheism."
The proposition that miracles cannot establish true belief may, according to Spinoza, be derived from Scripture. For example, Deuteronomy
   13:2-5 speaks of false prophets who perform miracles and are put to death
   for their false prophecy. From here, observes Spinoza, one learns that miracles do not prove the truth of a prophet's words. This observation is in
   line with Maimonides's dictum, "One who believes by virtue of signs has
   defective knowledge, for the sign could have been performed by trickery or
   magic."
III. THE WILL OF GOD IS THE ORDER OF NATURE
Spinoza argues here that wherever the Bible speaks of God's will, decrees,
   or providence, it refers to natural causes alone. Thus, God tells Samuel He
   will "send" Saul to him, but in fact Saul had been seeking his father's lost
   asses, and, at his servant's suggestion, came to Samuel to get help in finding
   them (I Samuel 9:3-16). Again, the Psalmist says God "changed the heart"
   of the Egyptians to hate the Israelites (Psalms 105:25), but their change of
   heart had wholly natural reasons (Exodus 1:8-10). Again, God tells Noah
   he will "set His bow in the cloud," but the reference is to the rainbow,
   which is produced by natural causes (Genesis 9:12-17). Again, the Psalmist
   says God sends forth His "saying" and "word," but the reference is to
   natural phenomena, such as the wind, the cold, or the melting of the frost
   and snow (Psalms 147:15, 18). Again, the Psalmist speaks of God's "messengers" and "ministers," but the reference is simply to wind and fire
   (Psalms 104:4).
Spinoza's argument here follows Maimonides, Guide of the Perplexed
   (II, 48), although only one of the five examples (Psalms 147:15, 18) is borrowed from that discussion. Like Maimonides, Spinoza explains that the
   Bible often ignores natural causes, and attributes things directly to God.
   Spinoza adds that the reason for this rhetorical device is the Bible's aim "to
   impress devotion in the soul of the vulgar," and its consequent appeal to
   the imagination not the intellect. In any case, Spinoza concludes, whatever
   is related in the Bible, even if it seems contrary to Nature, is to be understood as having in reality happened natur aliter.
Spinoza supports his argument by noting that biblical reports of miracles are often accompanied by naturalistic details. For example, the plague
   of boils, wrought against the Egyptians, was inaugurated by Moses' spreading ashes in the air (Exodus 9:10), and the plague of locusts was brought
   about by an east wind blowing all day and night (Exodus 10: 13). Similarly,
   the splitting of the Red Sea was caused by "a strong east wind" (Exodus
   10:21; cf. 15:10). When Elisha the Prophet revived the boy thought dead,
   he had to lean on him several times until his flesh warmed and he opened
   his eyes (II Kings 4:34-35). Again, Jesus, in order to cure a blind man, spat
   on the ground, made mud out of the dirt and spittle, anointed his eyes with
   the mud, and sent him to wash in the Pool of Siloam (John 9:6-7).
   Summing up, Spinoza writes:
We . . . conclude absolutely that all things that are narrated in
   Scripture as having truly happened have, like everything else, happened necessarily in accordance with the laws of Nature; and if
   something is found that can be demonstrated apodictically to contravene the laws of Nature or that cannot possibly follow from
   them, it is plainly to be believed that it was inserted in Sacred Writ
   by sacrilegious persons. For whatever is contrary to Nature is contrary to reason, and what is contrary to reason is absurd, and thus
   should be rejected.
IV. THE METHOD OF INTERPRETING MIRACLES
Spinoza now expounds his method of interpreting biblical miracles. Beginning with a psychological observation, he states that in relating events people are almost always influenced by their own opinions. He cites the miracle
   at Gibeon as an example of this, and remarks that in reporting it the Israelites did not say only that there was prolonged daylight but also that the sun
   stood still. The claim that the sun stood still did not only serve to explain
   the prolonged daylight, but also was a polemic against the pagans, who
   worshipped the sun. Thus, the fabulous notion that the sun stood still was
   concocted by the Israelites not only out of scientific ignorance, but also for
   the sake of religious polemic. In interpreting the miracle at Gibeon, therefore, one must take into consideration both the scientific and the religious
   opinions of the Israelites. It will be noted that Spinoza has embellished his
   explanation of the miracle at Gibeon (as given in chapter two) in accordance with his new conjecture regarding the polemical origin of the belief
   in supernatural miracles.
The second point that Spinoza makes with respect to the method of
   interpreting biblical miracles is that the Bible often reports "prophetic representations" (repraesentationes propheticae) as if they were actual historical events; and thus it is crucial for the biblical interpreter to distinguish
   between events that are to be understood as having really happened and
   those that are to be understood as merely visionary or imaginary. For example, when describing the Revelation at Mount Sinai, the Bible says God
   "descended in fire" from heaven and the mountain was "altogether on
   smoke" (Exodus 19:18; Deuteronomy 5:22-24). Spinoza affirms that
   descriptions such as this are "surely only representations adapted to the
   opinions of those who handed them down to us as they were represented
   to them, namely, as actual matters." However, he continues, "all who are
   somewhat wiser than the vulgar" know that God, the summum ens, does
   not move, but is "absolutely infinite" and contains all perfections. Spinoza
   then explains that a great many things in the Bible have been adapted to
   the opinions of the vulgar, who follow their imagination not their intellect,
   and "should not be accepted as real by philosophers."
The final point that Spinoza makes regarding the interpretation of bib-
   lical miracles concerns idioms and metaphors. The interpreter of the biblical text must become familiar with common Hebrew idioms, and be careful
   not to make the error of taking metaphors literally. For example, Zachariah
   says regarding a future war that the day shall be "not day nor night" and
   "at eveningtime it shall be light" (Zechariah 14:7; cf. Isaiah 13:10).
   Although this may sound like a supernatural event to those who do not
   know Hebrew, the figure of speech here merely means that the outcome of
   the war shall appear doubtful during the day, but be decided in the evening. Similarly, when the Bible says that God "hardened Pharaoh's heart"
   (Exodus 4:11, et al.), it means only that Pharaoh was obstinate. Again,
   when it says that "the windows of heaven opened" (Genesis 7:11), it means
   only that it rained hard. (Warren Zev Harvey, 'Spinoza on Biblical Miracles', Journal of the History of Ideas, Vol. 74, No. 4 (October 2013), pp. 659-675: 662-6.)


If durva is not available then what can be offered to Ganesh ji as a substitute?

Question: Its difficult to get durva by me so what else can be offered to Ganesh ji, instead of durva.
Comment: What is your opinion about my answer? Is that what you're looking for?
Comment: Your answers are good. Somebody told me to mix red kukun with rice and offer that. Some other told me to offer kheel to god. Am very confused.
Comment: Yes rice grain mixed with turmeric/kumukum/vibhuti can be offered in place of anything. Offering simply water is also correct from the scriptures point of view. In water all gods reside. You can use the mantras given in my answer while offering or you can do it without using any mantra as well.
Answer: What we offer to the deities is called UpachAra. When a particular UpachAra can not be arranged for, then a substitute (anukalpa) is always prescribed.
Quoting from Anhika Kritya (by ShyAmA Charan Kavi-Ratna VAridhi), first BhAga, 1st Khanda (p 30):

Substitute for honey (madhu) is jaggery; for ghee it is sesame oil;
  for all things it is jaba (barley); substitute for all flowers is
  DurvA or Atapa tandul (unbroken rice or akshata); substitute for all kinds of musical instruments is GhantA (bell) substitute for all
  UpachAras is water (udaka).

In his support, the author quotes verses from two sources. Given below is one such verse from the Nrisimha PurAna, which states that, in the absence of any UpAchAra, water can be offered instead.

alAbhe sarva-dravyAnAm udakenApi pujitAha (One must worship with water instead when any other ingredient is missing) | Yo dadAti swakam sthAnam sa tvayA kim na pujitah || (Nrisimha PurAna).

So, you can say "nAnAvidha parimala patra-pushpAni arthe (artham) udakam samarpayami" (I'm offering water in place of various fresh flowers and leaves) or more specifically "durvA arthe/artham udakam samarpayAmi" (I'm offering water in place of DurvA).
Some people also offer akshatas (unbroken riced mixed with a little of turmeric) in place whatever UpachAra that is missing but I don't have any scriptural support for that practice.
EDIT
The book "Nitya Karma PujA PrakAsh (Gita Press)" (p 297) also states that when any particular ingredient is missing from the PujA, akshata (unbroken rice grains), flowers or water can be offered. Or one can also mentally imagine to be offering those ingredients.

In the image above, in the option (Ka), it is stated that one can mentally imagine to be offering the ingredient (in your case DurvA grass) when it is actually absent.
The option (Kha) states, that in such cases, one can offer akshatas, flowers or simply water in place of the missing ingredient.


Adding RVM on production server with existing version of Ruby

Question: I have a server running an antiquated Ruby 1.8.6 that was the default with Ubuntu 8.04 and I need to upgrade to 1.8.7.  I'm thinking RVM is the best option for this, but I'm wondering if there are any pitfall with migrating everything over to this new version.  For example, if I set rvm to be the default for when I open a new console, how do I use the previously installed version of Ruby to stop my thin servers?  Anything else I should be cautious about?
Answer: This is a reasonable way to do it. You could use something like rvm wrapper to create a new thin executable which fires up the correct RVM:
<code>$ rvm wrapper your_ruby@your_gemset your_app_name thin
$ you_app_name_thin start
</code>
FWIW, There's also ruby-build, which provides less of a solution to the problem of managing multiple rubies and multiple projects on the same machine. But, one could argue that this "less of a solution" is actually "enough of a solution"). With ruby-build you might be able to directly refer to the full path to your thin installation, instead of creating a wrapper script.
Update: or you could use RVM shell, as I describe in this SO answer.


How can I improve security between Flash and PHP with URLRequests?

Question: I'm currently trying to communicate with a mySQL database with ActionScript3 using the URLRequest and URLLoader objects like so:
<code>loader = new URLLoader();
loader.dataFormat = URLLoaderDataFormat.VARIABLES;
loader.addEventListener(Event.COMPLETE, varsLoaded);
loader.addEventListener(IOErrorEvent.IO_ERROR, errGet);
loader.load(new URLRequest("php/comm.php?var1="+var1+"&var2="+var2);
</code>
Everything handled in the PHP is, as far as I can tell, secure and safe from would-be hackers and whatnot. MySQL injection problems are accounted for, private data is encrypted there, etc. Likewise, as far as I know, the PHP code is secure. Nobody is going to be able to access the actual source code of the PHP file. The swf file, however, is not so secure. I know there are countless ways to decompile them. With that, someone can easily find the above code and know that they can just go to comm.php in their browser and do whatever they like. In the context of the game this code is going into, that would mean that users could manually change their scores and whatnot.
Is there any way to improve the security of this transaction? I've tried running checks in the PHP code to ensure that the URLRequest is coming from the flash file and not a browser, but $_SERVER['HTTP_REFERER'] didn't seem to return anything.
Since the flash file and the php file are both stored on the same server, I was thinking there might be some sort of way to check if the connection is coming from the same IP address, but I wasn't sure how to go about doing that. I also considered that there might be some way to change .htaccess to block all access to the php/ directory, but I wasn't sure how to add an exception for the flash file.
Any help would be greatly appreciated!
Comment: You will never, ever, never ever ever ever never ever never, ever, infinity, have information sent securely from Flash to PHP. Send less fragile information across to PHP and have the server deal with the info to create a valid score. For example in a quiz game with highscores, I send a JSON object with the answers that the user selected as their IDs in the database. Then I use PHP to work out if those answer IDs are the correct answers and create the score there.
Answer: you can use RSA  ....
Action Script
http://www.yuniti.com/As2RSA
PHP
http://php.net/manual/en/function.openssl-public-encrypt.php
I hope it helps


What would be a secular interpretation of animal rebirth

Question: For people who don't believe in literal rebirth as animals,(secular or non)  how would they describe the mental state associated  with rebirth in the animal realm?  E.g, if stress is associated with hell rebirth, what mental state is associated with animal rebirth .
Comment: I recommend your elaborating your question, what mental state, the animal, the people?
Comment: Greed (貪), Anger (嗔), Ignorant (癡), Arrogant (慢), Distrust (疑) lead to rebirth in the Six Realms, they all get a hint of each but depended on inclination these mental states manifested as forms. Animal Realm is heavy with Ignorant, Asura with Arrogant, Greed the Hungry Ghost, Anger for Hell beings. For a human to be reborn as human again is a challenging task. Animal could be prevously human whilst human could be from other realms too, such as animal. Those have long history of believing in a soul or God-made-man, they rather believe it's mental state, not real animal form, that is wrong.
Answer: 'Animal birth' is described in many places in the suttas. It refers to ignorance (stupidity), lacking reflective reasoning (ayoniso manasikara), immorality & the merciless devouring of other beings, including mutual devouring.
Animals merely blindly follow & act upon instinctual drives & desires without having the capacity to reflect upon the consequences. This is the meaning of 'animal birth'.
Below are some quotes.

Bhikkhus, a god, a human or any other good state would not be evident from actions born of greed, hate and delusion. Yet, bhikkhus, from
  actions born of greed, hate and delusion a hellish being, an animal
  birth a ghostly birth or some other bad state would be evident. AN
  6.39

Sooner, I say, would that blind turtle, coming to the surface once every hundred years, insert its neck into that yoke with a single hole than the fool who has gone once to the nether world would regain the human state. For what reason? Because here, bhikkhus, there is no conduct guided by the Dhamma, no righteous conduct, no wholesome activity, no meritorious activity. Here there prevails mutual devouring, the devouring of the weak. For what reason? Because, bhikkhus, they have not seen the Four Noble Truths. What four? The noble truth of suffering … the noble truth of the way leading to the cessation of suffering. SN 56.47

Now on that occasion the wanderers of other persuasions had come together in a gathering and were sitting, discussing many kinds of
  bestial (animal) topics, making a great noise and racket. AN 10.93

Bhikkhus, these two bright principles protect the world. What are the two? Shame and fear of wrongdoing. If, bhikkhus, these two bright
  principles did not protect the world, there would not be discerned
  respect for mother or maternal aunt or maternal uncle's wife or a
  teacher's wife or the wives of other honored persons, and the world
  would have fallen into promiscuity, as with goats, sheep, chickens,
  pigs, dogs and jackals. But as these two bright principles protect
  the world, there is discerned respect for mother… and the wives of
  other honored persons. AN 2.9

The follow quote is important because it shows 'animals' can realise the Four Noble Truths, which also show this quote cannot refer to real animals but to people:

Beings (sattā) are few who, when they pass away from the animal realm (tiracchānayoniyā) are 'reborn' (paccājāyanti) among humans
  (manussesu)… those beings are more numerous are reborn in hell…. For
  what reason? They have not realised the Four Noble Truths. SN 56.102
  to 131

This video might help understand, which shows Angulimala, the mass-murderer, as a 'animal', being reformed or changed into a 'human' by the Buddha:
https://www.youtube.com/watch?v=uNzrKAzxipY

THE FIRST OF the Four Woeful States is hell. Hell is anxiety (in Thai, literally "a hot heart"). Whenever one experiences anxiety,
  burning, and scorching, one is simultaneously reborn as a creature of
  hell. It is a spontaneous rebirth, a mental rebirth. Although the body
  physically inhabits the human realm, as soon as anxiety arises the
  mind falls into hell. Anxiety about possible loss of prestige and
  fame, anxiety of any sort — that is hell.
Now rebirth in the realm of beasts is stupidity. Whenever one is inexcusably stupid about something: stupid in not knowing that Dhamma
  and nibbāna are desirable, stupid in not daring to come into contact
  with or get close to Buddhism, stupid in believing that if one became
  interested in Dhamma or Buddhism it would make one old-fashioned and
  odd. That is how children see it, and their parents too. They try to
  pull back and move far away from Dhamma and religion. This is
  stupidity. Regardless of what sort of stupidity it is, it amounts to
  rebirth as an animal. As soon as stupidity arises and overwhelms one,
  one becomes an animal. One is a beast by spontaneous rebirth, by
  mental rebirth. This is the second Woeful State.
The third Woeful State is the condition of a peta...
Buddha-Dhamma For Students

Please note: this is not a 'secular interpretation' but, instead, the true meaning of the suttas.
Comment: So the animal, ghost, and hell realms correspond to ignorance, desire, and aversion (anxiety), respectively?
Comment: I doubt "anxiety" (at least in modern understanding) is the right word to use in your context, nor do I see any connection to a "hot heart". Maybe some other descriptive words would be better?
Answer: Not keeping precepts, following the nose (mood), incapable of doing merits, lying around like a pig, eating like a dog, stngy like a mouse, dwelling in equanimity like an ox, such is called manussa-tiracchano, a human body but a behavior like an animal. If the question was about how to recognize such, this would be the answer.
Behaving like an animal leads to rebirth as such.
What leads to and rebirth as animal according the canon:

·Ten unwholesome actions (MN 41)
· Lack of virtue, holding to wrong views. If one is generous to monks and nuns, however, one may be reborn as an "ornamented" animal (i.e., a bird with bright plumage; a horse with attractive markings, etc.; AN 10.177).
· Behaving like an animal (MN 57)
from: The Thirty-one Planes of Existence
Comment: No Problem @Dhammadhuta , maybe you like to add:

Please note: this is not a 'secular interpretation' but, instead, the "true" meaning of the suttas.
Comment: I marked your answer down because, while I thought some parts of it were useful, particularly the 1st paragraph, it does not explain a 'secular interpretation' of AN 10.177, which the translation refers to "rebirth" as an "elephant", "cattle" or "chicken". http://www.accesstoinsight.org/tipitaka/an/an10/an10.177.than.html


How much variation in the human genome for humans

Question: We are currently learning about the Human Genome Project in high school biology. Wouldn't the human genome that was mapped be different from, say, mine if it was mapped? How much variation is there between individual humans in our genetic sequencing? I'm assuming there is not that much difference since multiple volunteers were used in the project. I did see another question that talked about mutation rate, so I'm not sure if that's the same thing.
Comment: Possible duplicate of [Why are the genomes of Humans 99.5% the same?](https://biology.stackexchange.com/questions/41974/why-are-the-genomes-of-humans-99-5-the-same)
Comment: @James — Perhaps we could do with a community wiki (whatever that is) on this whole topic. I think the current dispersed nature of questions relating to it makes it very hard to get a coherent view.
Comment: Welcome to Biology.SE! This is a very basic question and thus appears to meet this sites criteria for a [homework](https://biology.stackexchange.com/help/homework) question. In these situations we expect you to do some research on your own and then ask questions informed by what you have learned (ideally with references to reliable sources). For instance the "Related" links led me to [this question](https://biology.stackexchange.com/questions/41974/). ——— Please also take the time to go through the [tour] and the help pages starting with [Ask] questions effectively on this site. Thanks!
Comment: Hi Sarah, and welcome to Bio.SE! @tyersome I disagree that this is a "basic" or trivial question. So do the 500K genome project, gnomAD, ClinVar, Genomics England & BioBank, and countless other massive projects. Even post-sequencing, calculating the rate of variation is incredibly challenging. This question clearly is a fundamental question about genetics that has massive ramifications in rare disease, cancers, developmental disorders etc.
Comment: @David I think that I side with Sarah on this. Mutability (i.e conservation) and variation are fundementally different principles. Conservation (evolutionary constraint/mutability) are measuring changes of genetic regions over huge timescales by comparing homologous sequences in other species. Variation, however, is snapshot of what is currently varied in the population of a single species. Of course, there is a lot of overlap between constrained genes in gnomAD, for example, and highly conserved regions. Practically I'm not sure if this will be reflected in the answers...
Answer: You are correct in saying that the human genome sequenced in the project was contributed by a dozen anonymous volunteers. However, the final sequence that is used as a standard reference is a somewhat arbitrary construct that represents a collection of consecutive segments taken from one or other of the contributors. It is a haploid sequence, plus a Y and an X chromosome.
Now you ask how different are the genomes of any two subjects, taken at random from a population. Imagine for simplicity looking at your own genome. For each of the 22 autosomes, you know you have two copies, one transmitted from your father, the other from your mother (for the X chromosome you have two copies, if you are a girl). Now imagine comparing the sequence of each of your pair of homologous chromosomes side by side; remember that they are derived from very different individuals (unless your parents are close relatives), so that they will not be identical, as they represent independent evolutionary histories.
Then, the question becomes: how much variation is there between the sequences of your paired chromosomes? And the answer is known: approximately every 1,000 base pairs your chromosomes show a base pair in one chromosome and a different base pair in the other; otherwise they are identical. The sites where this variation occurs are called SNP, for Single Nucleotide Polymorphisms (many other kinds of variation exist, but SNPs are the more common). We can generalize this observation, as it remains true for any pair of chromosomes chosen at random from any pair of subjects. Therefore, we can say that humans are identical for 99.9% of their genomes, whereas the genetic variation responsible for the differences that allows us to recognize ourselves as unique are limited to 0.1% of our genome.
Comment: I think this answer gives a good basic overview to the question, for further detailed reading it would be helpful to include links about the already mentioned [SNPs](https://en.wikipedia.org/wiki/DbSNP) and also the [1000-genomes project](https://www.internationalgenome.org/about) (which is essentially about exactly this question)


How do I find people to jam with in my city?

Question: I've been going to my local music store to jam with people in the synthesizer section and guitar section. Aside from that, what other places/hacks have you found to jam with people in your area?
Comment: It happens by becoming friends with other musicians; if you go to small bar and neighborhood concerts, chances are that there are quite a few musicians attending them as well, friends of the band, etc.. I have found that people with the same passion regroup quite easily
Comment: On craigslist I found all my band members. And my significant one, after a couple of guitar+singing sessions :))
Comment: You ask 'in **my** city'. The answers may be different for different cities in different parts of the world...
Answer: It will depend on the city and what resources you have access to.
Connect to Students at a University
If you have a big university with a strong jazz department, they will sometimes sponsor jam sessions where you can meet people. Another way to get connected to the musicians at a university is to sign up for a music class (theory, performance, etc.). You can also take lessons with the university's piano/guitar teacher, which will often lead to relationships with people in the music program. Another option is to attend the concerts and make conversation with the musicians after.
Local Jam Sessions
If you live in a place like New York City, Nashville, Chicago, etc. then there will be plenty of clubs/bars that host jam sessions. You can show up to a jam and meet musicians that way. Even many smaller cities have at least one place that hosts jam sessions.
Look Online
On sites like meetup.com or craigslist, you might be able to find other musicians looking to jam. Or, if you're trying to reach out to professional musicians, you can convince a local bar, coffee shop, etc. to hire you for a gig. Then you can post on craigslist, etc. that you're looking for a drummer and bassist to hire for a gig.
Answer: There's always jam sessions at open mic nights, where attendees are expected to play with others. You may go there as a solo artist, or sit in with a couple of friends with whom you've rehearsed several numbers. At the better open mics, someone will organise who plays with each other, and that can be challenging and fun - playing with folk you've never even met before. When you get better at it, you might even become part of the house band, ready to accompany anyone who turns up. That's the bit I love best.
Otherwise, adverts in music shops, schools, colleges, local rags and social media should find like minded people.
In UK (don't know where you are!) there are sites like 'Join My Band' and 'Bandlist' which provide opportunities for musos to contact each other, to join bands, or just jam.
Answer: Check with MEETUP.COM to see if there are any music groups in your area who imbibe in jamming.  Also, check out the Musicians Section of Craigslist.  Yes, yes, yes, yes, yes. I know, Craigslist is filled with murderers, sex addicts, drug dealers, burglars and muggers.  Skype first, ask for a video sample, meet first in a coffee shop.  You'll know if you are talking to a real musician or not.
Consider joining a community theater group and play in the orchestra.  It is not jamming per se but you will glean valuable disciplinary skills working with other musicians.
Find out if there are any community bands such as orchestras or big bands and inquire about joining.
There are also several software programs that you can jam along with.  They are not ideal but may be worth looking into.   Music Minus One is the industry standard.
Finally, join a church that plays in the style you are interested in.  Many have bands, folk groups, orchestras or small groups where jamming is de rigueur.
Comment: Most of the players I know imbibe *while* jamming...


Virtual Machine Configuration that Can be Up and Running Instantly

Question: How to create a virtual machine with a pre-installed OS and applications up and running instantly in any PC?
I'm using shared PCs in the library which have special hardware that will regenerate the harddisk image after a reboot.  Although I can use their hard disk freely but any applications installed will be lost after reboot.  I want to be able to run my applications instantly without having to reinstall everything after every reboot.  Furthermore, I need to be able to install those applications that require reboot during their installation process.
My idea is to use a Virtual machine.  Installing a Virtual machine is the only overhead I need to bear with which is acceptable provided that the virtual machine installation doesn't require reboot by itself.  VirtualBox is a good candidate.  But the problem is that I have quite a large volume of preinstalled applications which cannot be fitted into a single DVD/USB drive.  The PCs have 1 DVD drive and 2 USB ports, so I can combine them for my need.  But, that would means my virtual disk image file must be split into 3 physical files (1 in DVD, 2 in 2 USB drives) in order to be up and running INSTANTLY (ok I can zip a large file into multiple DVDs but that requires a lengthy unzip process).
Questions:

How to make VirtualBox (or any other
virtual machines) to split the disk
image file (.VDI) into multiple
files that can be used instantly. Is
it via snapshot?
Apart from virtualbox is there
anyother virtual machine that does
not require reboot during its
installation process?
Answer: Why don't you get an external hard drive? You can get a 1 terabyte drive for $100-$150. It would connect using USB and allow you to have a massive .VDI file.
This doesn't answer your questions, but it may answer your problem.


If everybody DNA is different then how blood can match even with matching blood group?

Question: We know that everybody's DNA pattern is different in the world. Then how can ´we transfer blood from one person to another person and this person can survive ?
Answer: A few components to my answer.

Red blood cells do not contain a nucleus, therefore, they do not harbour DNA.
The major determinant of blood compatibility is the blood antigen. There are only 4 types: O, A, B, AB. This is genetically encoded, and is expressed as a set of sugar coats on the blood cell membrane. However, the enzymes that encode for A or B should be identical from person to person.

I hope this gives you a preliminary answer to work off.
Answer: Because one's DNA doesn't have to exactly match another person at all 3 billion locations for the transfusion to be successful.  As it turns out, there are only a few proteins that determine whether a person's blood is a match to someone else's.  And as it turns out, in the vast majority of the human population, there are only three alleles of the ABO gene, and only two alleles for the Rh gene, and for the vast majority of cases, compatibility of those two proteins is all that you need.
Answer: It is critical for you to realize that one's DNA is not the determining factor when it comes to a blood transfusion. Rather, what you have to look at is the proteins being expressed by the DNA coding for blood-associated proteins, as it is these proteins that are the determinant of blood acception or rejection.In other words, the key question is whether or not the blood being transfused harbors antigens -- specific blood proteins associated with a given blood genotype like A & B -- that are foreign to the recipient.
Individuals that have type A blood express A-type antigens, but also house anti-B antibodies which specifically bind to blood with the B antigen. For a person with type A blood (AO or AA), transfusing either AB or A type blood would be dangerous. The RBC in both cases would house B antigens, which the recipient would respond to the transfusion by initiation an immune response against the blood.
I want to touch up one more time on your connection of DNA to rejection of blood. Please be careful with this as different DNA really does not mean much in this case OR in many other biological cases. You have to be much more specific and ask what is the DNA encoding, what is is transcribing and eventually translating and how that relates to the biological process in question. For blood type, although every individual has 'different' DNA, their DNA for blood type has 3 distinct alleles to consider --iO, iA and iB. These alleles are located only within a small region of a person's overall DNA and the difference are 3 discrete categories, as opposed to every person having a different allele and expressing a different protein. If every person different over this small segment of DNA, in the DNA coding for blood type, then indeed it would be possible for each person to make unique antigens and thus for all transfusions to be rejected.
However, since the differences  encompass only 3 allele types, people can only have a limited range of genotypes (aO, aa, bo, bb, ab, oo) which connect to only 4 distinct phenotypes (A, B, AB, O). So there is different in DNA, but the difference is defined and limited, so that overlap of genotypes between is possible and compatibility is quite common. So yes people differ in that DNA, but you have to ask if those differences are significant for a particular biological phenomenon.
Comment: Welcome to the site. I appreciate your effort in answering the question; it would be even better if you can make your answer more precise by avoiding repetition of previous answers.
Comment: Since the antigens are genetically encoded DNA IS  the determining factor when it comes to a blood transfusion. Just not all of it.


Does the WTO itself have any input into trade agreements?

Question: Does the WTO itself have any input into trade agreements, or is it merely a forum for sovereign states to negotiate and settle disputes?
Comment: if you actually meant schedules instead of "trade agreements", you should ask another questions about that. There's a limited role of WTO itself in those.
Answer: No. The WTO as an organisation doesn't make decisions. Countries do not delegate decision making power to the WTO as an organisation, a 'forum' is a pretty good description, if one is only talking about trade negotiations.
The WTO has more power than just a forum, however, when it comes to arbitrating existing agreements.
The WTO describes itself as a:

"a rules-based, member-driven organization—all decisions are made by the member governments, and the rules are the outcome of negotiations among members"

There are multiple committees, but the one you're probably interested in is the Trade Negotiations Committee. Like the others, it is made up of representatives of each country.

Negotiations shall be open to:

(i) all members of the WTO; and
(ii) States and separate customs territories currently in the process of accession and those that inform members, at a regular meeting of the General Council, of their intention to negotiate the terms of their membership and for whom an accession working party is established.
Decisions on the outcomes of the negotiations shall be taken only by WTO members.

The closest thing to someone "representing the WTO" is the chairperson of these committees. But their role is to facilitate and help the members reach consensus. All decisions are taken by the members.
Where the WTO is more powerful than a forum is in dispute


How can I put advertising on my MediaWiki site just like at Wikia.com?

Question: I want to put some AdSense blocks on a wiki I'm running. I guess that Wikia has highly A/B tested their ad placements so I'm going to follow them a little bit there. Unfortunately the list of extensions at Wikia is enormous and it's not clear which ones are used for ads on the wiki.
Here's some related HTML:

It could also be that all the ads are part of the skin but to avoid problems with upgrading I would like to avoid modifying the default MW skin and stick with using extensions. So if Wikia is indeed doing it through the skin, which extensions should I go with?
There are three versions of MediaWiki AdSense extensions (completely different code bases actually) and then there's the MediaWiki Widgets solution.
The Widgets solution is probably quite clean, but then it's creating widgets that are supposed to be inserted into articles. I want the ads to be generically inserted on all pages of a specific namespace instead of manually adding them. Is there a solution for that?
Answer: Choose a skin optimised for ads.
The first result is Skin:Refreshed.


Why is King Kai still dead?

Question: Near the end of the Cell Saga, Cell inflates its body in preparation to destroy the earth, but Goku thwarted its plans by teleporting it to King Kai's planet. As a result, King Kai and Goku were both killed by Cell's explosion. After Cell was finally defeated, however, they used the Dragon Balls to revive everyone killed by Cell. Goku wouldn't be revived since he was already brought back once, but shouldn't King Kai, Gregory, and Bubbles have been revived? Cell was the direct cause of their deaths.
Comment: because who was it that *moved* the bomb called Cell to King Kai's Planet?
Comment: @Memor-X So what you're saying is that Goku is more responsible for King Kai's death because Cell had no intent to kill King Kai, but Goku was fully aware what would happen if he teleported Cell to King Kai's planet. Therefore, Shenron considers it to be Goku who killed King Kai. Would you like to write an answer about that?
Comment: i would but i don't have the confidence i can form a good enough answer unless i re-watch the episode to confirm some stuff. watching Team Four Star's Abridge version New Shenron would have had 3 wishes like Porunga but it was nerfed to 2 to remove the "only 1 resurrection" catch which Shenron had and i know Goku said to the others that he didn't want to bring him back citing all the previous threats to earth came because of him. just need to check the first wish to confirm what another factors could've stopped Goku being resurrected in the first wish
Answer: The exact wish (at least in the english dub) was

Please revive all those on Earth who were killed by Cell.

That doesn't include the others who died on King Kai's planet.
Comment: The wording in the English dub of Kai spoken by Yamcha was "For our first wish, we want you to bring back everyone who was killed by Cell." I'm assuming your wording comes from the original series. In this case, further investigation into the Japanese versions and the manga would improve this answer.
Comment: Also in Kai, Piccolo expresses disappointment afterwards that Goku wasn't revived (evidently he was holding onto a faint hope that the new Shenron would be able to revive him). According to the wording of the wish you've given, Piccolo would have no reason to believe Goku would be revived since he was neither killed by Cell on earth, nor is he currently on earth. Of course, it's possible Piccolo wasn't aware Yamcha made the "wrong wish".
Answer: When Goku was talking to them he explained that King Kai could have been brought back to life by the wish but refused so he could stay with Goku and guide him around, but why he needed to be dead for this was never explained. Two fan theories I've read to explain this is that he couldn't enter heaven unless dead and that by being dead he could ignore his duties as North Kai, neither of these make sense to me though as we see a lively South Kai in heaven in the manga and we cannot say what is actually required of him in regards to his Kai duties of which we assumingly see him having resumed back on his planet in Super whilst still dead.
So to get back to your question he chose not to be revived at the time and Goku never attempted to revive him since, due to forgetting and not seeing it as a big deal since he's a god, until King Kai expressed his desire for it.
Comment: I've also seen this in forums, but it wasn't sourced. Do you know what volume or manga chapter that was in? The anime episode would also be acceptable (though I'd prefer the manga). The exact quote of what King Kai said would also be good.

Why is King Kai still dead?


Delete a rented movie that is only partially downloaded

Question: I rented a movie and actually was able to watch it, but in iTunes it still shows up as a download in progress with an error and when I tap the icon it just says I don't have enough memory to continue the download (for the movie that I already watched and the rental time expired for). It is taking up a bunch of space and I want it gone!  Please help. I do not have a computer I can get onto at this time and don't want to lose my 100+songs currently stored on my iPhone.
Answer: Somewhat bizarrely it is not possible to delete downloads in the iPhone iTunes.
The only way to delete the download, is to contact Apple (the iTunes section) and they will delete it for you. (you can contact support through the desktop iTunes app, or here)
Answer: Yeah agree with Jonathan, explain that you've already seen it, that it is causing issues and you want it removed from your downloads queue. They should have no problem doing so for you.


Can I do iPhone game dev on iPod touch?

Question: I do not want a mobile phone, but are there any issues I'd run into by developing games on an iPod for iPhone?
Answer: There is no problem with developing for the iPod touch. Most testers had those as primary hardware where I worked before.
One thing the iPhone was used for (apart from specific hardware bugs) was incoming phone calls. But now you can simulate those on the ipod touch with FaceTime.
I think there were months where I had only iPods with diferent iOS versions during dev. The iPhone is definitely not mandatory.
Hope this helps.
Edit: Actually due to the memory limitations it is a much better idea to develop for the iPod touch rather than the iPhone. This way you will deliver a product which will run properly on a larger number of devices.
Answer: You will not be able to test or run higher end games and graphics as the iPod Touch hardware has not been kept up to date with the latest iPhone and iPad hardware.  If you are only interested in simpler games and graphics, though, there should not be a huge issue.  You'll want to have some friends test your game on the other iDevices before publishing it, though (always a good idea in any case).
Comment: Ah, you're right, the 4g iPod Touch is more up to date than I thought.  I completely missed that.  It does still only have half the RAM of the iPhone 4, but that's not quite so much of an issue..
Comment: I was doing some comparison with the 4G iPod touch and it looks like it has about the same specs as the iPhone 4 (not 4S). I'm not sure what the adoption rate is of the 4S, but I think it's probably a minor issue for the kind of games I am interested in writing.

Can I do iPhone game dev on iPod touch?


Inactive State of buttons, to hide or not to hide...that is the question

Question: On a windows based LOB application for data capturing. Is it better to hide a button completely when it is inactive, or simply show a disabled state for the button.
Comment: Possible duplicate: [Don't hide or disable menu items?](http://ux.stackexchange.com/questions/12756/dont-hide-or-disable-menu-items?rq=1)
Answer: As with so many questions regarding UX, the answer starts with 'It depends'. This is because UX is inevitably based on context and action.
Some arguments for using a disabled state:

Even if not in use, the user has a chance to learn that the action is possible. You may even have a tooltip explaining the criteria for use.
The user can learn where controls and buttons live within the interface. This assumes that if a lot are hidden at one time the structure would be less clear. (Depending on your design).

Some arguments for hiding the button:

Clarity. Only showing what is needed for the task at hand. Attention is focussed.
It allows you to change the controls, using the same space for different means. Gmail does this. This is handy when there is a lot going on.

The questions you should ask yourself are

"What does the user need to know at this point?"
"What does the user need to do at this point?"

Remember that no screen is in isolation. Each frame helps tell the story. So if you can establish an idea or pattern previously the requirements for this screen may change.
While simplicity is a great goal (potentially supporting not showing the button) you should never simplify more than necessary. Therefore if the user needs to know about the existence of the button, or you need to build the context, you might need to consider it.
A good testing regime should tell you this.
Comment: Very concise - makes me feel like I maybe didn't put enough effort in to my answer now! Upvoted :)
Comment: Good summary - though worth noting that there is a third option: leave the control active and message the user if they interact with it outside of full compliance. This latter option can be nice because it doesn't require any explanation for a disabled control. It can be good for forms, particularly long ones if you scroll the user to the first offending field, and seems to be preferable to disabling controls in many places I've experienced.
Answer: I would suggest that hiding the button completely can add confusion for the user, as the other (unhidden) options might not make as much sense when you don't know the alternatives.
Allow me to give an example:
If the button which the user can see is "old" and there is an opposite button hidden - the hidden button could be "new" or "young" as they are both opposites of the same word.
OK, that's not an ideal example, but I do think users like to have a more complete holistic view of the situation they're in and hiding data may remove from that.
Some might say that if the other button is disabled it doesn't matter as the available option is still the same, but I would still argue that a user should be given as much information about their position in the UX as possible.
Answer: I agree with Jay that it depends. But here's one guideline you might want to consider: Only hide a button if the user's permissions determines they cannot do the button's action. This way each user will get a consistent view of the product, which may change from user to user.
Answer: I agree with the it depends answers. But to break it down as good as I can in this situation you should check which information the button communicates if it's hidden or displayed. Do a user flow for this part and you will see if the user could stuck on the hidden button or not.


How to add vpn subnet to a private local subnet (both in different subnet address)?

Question: I set up a xl2tpd vpn server on a router, and assigned the ip range from 192.168.191.2 to 192.168.191.244, and there's local network behind the router's lan side with a 192.168.1.0/24 ip range, so I want the vpn client access the router from its wan port, then it can communicate with the local network, so how can I got it? I wonder to known how to set up the route rules to make it up, so any tips?
Answer: Is you setup like this?

  (internet)
      |
      |
 [                  ] the ISP router is your WAN gateway access to the internet, and
 [your ISP's router!] provide your WAN area of, say, A.B.C.D/28 (for example)
 [                  ]
   | the isp's router ip in your wan network is, for example,
   | A.B.C.E, which is the default gateway you need to setup in your router!
   |
   |  {your router wan ip: A.B.C.D/18}
    `-[      ]...{serves all vpn guests in 192.168.191.x/24}
      [router]
      [      ]-. {your router LAN ip :192.168.0.1/24}
               |
               |    [LAN's switch] (for all 192.168.0.x/24 hosts, including router's LAN port)
               |     | |  |  |
                `----' |  |   `-- other 192.168.0.y/24 host
                       |   `-- other 192.168.0.z/24 host
                        `-- etc...

Then your router already knows about : the LAN, the vpn guests, and the internet.
On it, no special routes should be added: it should already have one for the LAN, one for the guests, and the default one for Internet. It can send packets: to 192.168.191.X/24 (via his ip in that virtual lan), and to 192.168.1.x/24 (via his other IP in that real LAN), and send everything else to its wan default gateway (provided to you by your ISP. If your have, say, a /28 lan, then the router WAN ip is a.b.c.d/28 and the ISP also gave you the default gateway as a.b.c.E, another ip in that a.b.c.d/28 range where their own router resides.
Now the LAN pcs: they should have their default gateway set to the ROUTER's LAN ip. Then no special route needed for them either : they will do "oh, a packet destined for 192.168.191.x, when my LAN is 192.168.0.x/24 ? not in my LAN, and no special route for this network, so I send it to my default gateway (ie, the router) to be handled there"
Now the VPN Guests: should be already served a 192.168.191.x ip and have as default gateway the ROUTER's 192.168.191.1 IP, so no special route needed for them either! (a packet destined for 192.168.1.x will, with no special routes setup, be sent to the dfefault gateway, the router, who happens to know how to handle them to destination)
So, nothing to do. If you need routes, it's probably because you have a different setup than the above (maybe you have special needs, or additionnal networks to reach via a specific gateway/router), or that some basic thing weren't setup properly during the above networks and IP configs declarations.
Comment: additionnaly, on your router, wou probably can (and should) define who can access what, and how: can your VPN guest access things on your LAN? and the opposite? can they access each other? each time, define what they really need to have, do not give out a "everything" rule, too easy for hackers to take advantage of. Decide what they really need to do wich each other: icmp ping? ssh? (ssh also gives sftp and scp) rdp? other?
Answer: You are defeating the purpose of vpn's. The remote lan should not communicate with local lan.
However you can tweak it.
Design for the same subnet throughout and exclude host you do not want to expose from NAT.


Should Document files on web pages open in a new tab/window?

Question: When designing web sites should document files such as PDF, DOC, XLS, should the documents open in a new window/tab or in the current tab?
Comment: Vitaly provides a good link that should give you some additional information. However as this question is specifically around *documents* opening in new tabs and not just any pages then you should get some more specific answers to that question here. If any answers are more explicitly around web *pages* opening in new windows then that link above should be used otherwise we risk duplicating answers across two questions. Hopefully these questions can be kept separate.
Comment: possible duplicate of [Opening website external links in new window -- published usability tests](http://ux.stackexchange.com/questions/19892/opening-website-external-links-in-new-window-published-usability-tests)
Answer: Jakob Nielsen has an (old) article that deals with your issue:
 Open New Windows for PDF and other Non-Web Documents
How about having 2 actions for documents: Download and View?
Here's some examples:
Cloud App

Gmail
Comment: But note that 'view in your browser' is not a guarantee. A word file, for instance, won't open in everyone's browser. It's entirely dependent on variables out of your control. (note that google handles it via google docs, which is a nice solution...if you've happened to write a MS Office compatible online office suite)
Answer: You never have to use target="_blank", if users wants to open it on a separate window can choose to do that, but you should not force someone to open a new window.
Answer: I would suggest that you open your documents in a new window. Mainly because some documents like pdfs could possibly break browsers navigation if a user clicks a link inside. By opening documents in a new windows you can prevent this. In my experience its more frustrating to completely lose my prior navigation that having a document open in a new window/tab.
Also note, for accessibility reasons you should let the user know when a page/document is going to open in a new window.
Comment: The problem is you *can't* reliably do that. It's up to the browser/user/OS/device as to what happens with non-web files.
Answer: You have no control* over document formats that the browser doesn't natively support. They may open in the browser with a plugin. Or they may download. Or they may open in an external application of the browser and/or end-user's preferences.
As such, you should not open a new window, as you have no control over it.
Instead, let the end-user know what kind of file they are about to click on, and then they can handle the rest to their own personal preferences.

the one exception is that you can force the save dialog to appear if you stream the file from the server. That's sometimes a useful thing to do.
Answer: I've always liked providing the document type and size in the link and letting the user's native applications open the file.
e.g.,
[a href="report.pdf"]Annual Report (PDF, 233Kb)[/a]
This lets the user know that it is not a web page (and doesn't act like one), and also gives them information on the size so that if they think it's too big or will take too long to download, they can skip it.


Webform Tokens lets me access form meta-info but not user-submitted values (with Fill PDF)

Question: I'm attempting to use the Fill PDF module to populate an editable pdf. The data source is a Drupal Webform submission. I'm specifying those values to Fill PDF using tokens from the Webform Tokens module.  I have also tried this using Webform's tokens made available to Fill PDF via the Webform Rules module, which does not work at all (no PDF is generated).
With the Webform Tokens module I have partial success: I can get a PDF to fill in with non-user-submitted values from the webform (such as the submission ID and the webform component label) but user-submitted values always end up blank. For example:

I enter the following into the Value field of the PDF-Field key in /admin/structure/fillpdf/[form ID]/edit/[pdfkeyname]:
The SID of this submission is [webform:meta-sid].
The value of the form component titled [webform:meta-label-textmetest]
is [webform:val-textmetest].`

For the submission in question the value of the textmetest field is "glasstest."

I go back to /fillpdf?fid=53&webform[nid]=4&webform[sid]=10 and it now reads
The SID of this submission is 10.
The value of the form component titled textmetest
is  .

Thus, the [webform:meta-sid] and [webform:meta-label-textmetest] tokens are being replaced, but not the token [webform:val-textmetest].
I have confirmed that the webform's ID is indeed 4, the SID is 10, the value of textmetest for SID 10 is glasstest, and the form ID for the pdf is 53.
I know that it is trying to access a specific submission, because if I use a nonexistent SID in the URL (e.g., /fillpdf?fid=53&webform[nid]=4&webform[sid]=99) the field reads: The SID of this submission is . The value of the form component titled  is  . , i.e. the SID and title don't populate for a nonexistent submission. However, I can't get at the values for any specific submission.
If I try Webform Rules enabled instead, instead using the tokens [webform:sid], [webform:textmetest-value], and [webform:textmetest-title], which are the corresponding tokens that Webform Rules exposes to Fill PDF, it does not even generate a PDF; I get a 500 internal server error.
Does anyone have any suggestions, either for how to make this work or for another way to get at webform values?
Answer: The issue is that Fill PDF 7.x-1.9 doesn't work with Webform 4 due to a change in the structure of the $submission variable from Webform via webform_get_submission().  See this post for an explanation and an ad hoc fix.


How long can one drive using an Indian Driving License in California?

Question: How long can one drive using an Indian Driving License (in English) in California? I have tried to research this one, but there's conflicting information on the Internet. Some say 1 month, some say 3 and while there are few accounts of 1 year too. I tried looking up the DMV website, but couldn't find any info.
Comment: If you mean you moved to California.  This would really be a question for the expats site. But note that: Cali has on the order of *five million* illegal immigrants. (Almost all of whom simply drive with no license at all.)  It is inconceivable you'd get in to any issues, at all, for using your foreign license for too long - you know?
Answer: It depends on if you are a visitor or if you are a Californian resident. Visitors are allowed to use their foreign driver's licence without limitation. If you become a resident of California, you must obtain a Californa driver's license within 10 days.
Source: California DMV
Comment: Again, the number of new residents over-doing that "10 day limit" would be literally some millions of people!


USB-C hub to turn 1 USB-C port into 2/3

Question: I recently got an iPad Pro and want to charge it the same time I am listening to music. I have the Apple 3.5mm jack and most adapters to turn that one port into charging + 3.5mm didn't seem very good.
I am looking for a very simple portable hub (not a fancy dock with display-out, ethernet and what not) that just turns that usb-c port into 2, so that I can charge it and listen to music at the same time with the stuff I already have, or other potential usecases in the future.
Answer: I believe a standard USB-C splitter would do the job, no?

USB-C hub to turn 1 USB-C port into 2/3


What is the maximum allowed difference between two altimeters for flying in RVSM airspace?

Question: What is the allowable altitude difference reading between two altimeters while flying inside RVSM airspace?
Comment: I added the FAA regulations tag because I noticed in a comment that you're looking for a FAR. If I misunderstood, you can just edit again to clarify.
Comment: Should not be double the allowed measurement error of the single device?
Answer: On the ground during the preflight check, the altimeters must be within 75 feet of each other.
In-flight the altimeters must be within 200 feet of each other.
I have been flying the B777 for about 8 years and I have never seen the altimeters disagree by more than about 10 feet, either on the ground or in flight.
Comment: Appreciate your response, that's what I though initially I flew for a company that only allowed 50ft difference between altimeters in RVSM wondering if their is a FAR to back this up.
Answer: I couldn't find an FAA regulation, but AC 91-85B Authorization of Aircraft and Operators for Flight in Reduced Vertical Separation Minimum (RVSM) Airspace
Document Information page B-4 says 200ft:

At cruise FL, the two primary altimeters should agree within 200 ft
  (60 m) or a lesser value if specified in the aircraft operating
  manual. (Failure to meet this condition will require that the
  altimetry system be reported as defective and notified to ATC.) Note
  the difference between the primary and standby altimeters for use in
  contingency situations.

It also says on page B-3 that before takeoff both altimeters must be within 75ft of field elevation:

The aircraft altimeters should be set to the barometric pressure for
  local altimeter setting (QNH) and should display a known elevation
  (e.g., field elevation) within the limits specified in aircraft
  operating manuals. The difference between the known elevation and the
  elevation displayed on the altimeters should not exceed 75 ft
Answer: Piling on to an earlier answer, but with some more tangible references.  Noting that your post doesn't specify which country you're flying in, there does seem to be an international standard (defined by ICAO).  I highly recommend using this resource to help understand several relevant regulations.
Starting with the FAA...
The FAA regulation is found in Part 91, Appendix G.  The advisory circular referenced above is the most accessible way to process RVSM Requirements and is updated to the newest RVSM law (from Jan '19).
From the advisory circular:

A.5 Altimetry System Performance.
A.5.1 General. The statistical
  performance statements of International Civil Aviation Organization
  (ICAO) Doc 9574, Manual on a 300 m (1,000 ft) Vertical Separation
  Minimum Between FL 290 and FL 410 Inclusive, for a population of
  aircraft are translated into airworthiness standards by assessment of
  the characteristics of ASE and A-9 1/29/19 AC 91-85B Appendix A
  altitude control. The following standards differ in some respects from
  that document, but they are consistent with the requirements of RVSM
  and in accordance with 14 CFR part 91 appendix G, section 2.

Here, you see FAA concordance in spirit and substance with ICAO.  If you're interested in the nuanced details which defines a valid altimetry system for certification, you should read this entire section.  In short, it defines a max standard deviation of Mean Altimetry Symmetry Error (how much the altimeters differ) at 80ft, and 3 standard deviations at 200 ft.  This is then used to derive the inflight guidance found in Appendix B:

At cruise FL, the two primary altimeters should agree within 200 ft (60 m) or a lesser value if specified in the aircraft operating
  manual. (Failure to meet this condition will require that the
  altimetry system be reported as defective and notified to ATC.) Note
  the difference between the primary and standby altimeters for use in
  contingency situations.

Moving to ICAO, you can see ICAO Verbiage here:

In respect of aeroplanes for which the characteristics of the airframe and altimetry system fit are unique and so
  cannot be classified as belonging to a group of aeroplanes encompassed by paragraph 1, the height-keeping performance
  capability shall be such that the components of the TVE of the aeroplane have the following characteristics:
a) the ASE [Altimetry Symmetry Error] of the aeroplane shall not exceed 60 m (200 ft) in magnitude under all flight conditions; and
b) the differences between the cleared flight level and the indicated pressure altitude actually flown shall be symmetric
  about a mean of 0 m, with a standard deviation no greater than 13.3 m (43.7 ft), and in addition, the decrease in the
  frequency of differences with increasing difference magnitude shall be at least exponential.

Finally, it's interesting looking at the European Aviation Safety Agency (EASA) SPA Verbiage:

two primary altitude measurement systems. A cross-check between the primary
  altimeters should be made. A minimum of two will need to agree within ±60 m
  (±200 ft). Failure to meet this condition will require that the altimetry system be
  reported as defective and air traffic control (ATC) notified;
Comment: I appreciate your answer this is perfect I fly mostly domestic (US) but sometimes international this is great information. Thank you!
Answer: 50 ft to know ground in canada.  check out this sad story where two pilots choose the wrong answer and paid the ultimate price.  they choose to set PM altimeter to match PF - bad news was the PF altimeter was the one that was reading 130 ft too high.
https://www.tsb-bst.gc.ca/eng/rapports-reports/aviation/2008/a08w0244/a08w0244.html?wbdisable=true
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).