Is there a modified version of the United States QWERTY keyboard with more symbols?

Question: I'd like to have the US QWERTY layout (so my keyboard still works,) but also have some addition symbols from other languages. It's almost like adding the Alt-Graph and it's features from the UK/Irish or Canadian French keyboard to the US QUERTY keyboard without having keys move (like @ being in a different position.) The reason I'm asking for this is sometimes having to bring up the Windows 10 character selector is a annoying when I just want a character such as the £ symbol. All I need is some software keyboard layout to make this work, I might try to experiment and see if an AutoHotKey script configured the right way might help.
Answer: The US keyboard is old before any international features were even thought of. US International Keyboard works like European keyboards for special characters using Alt Gr key.
The Right Alt (Alt Gr) Keys
Key Description
Right Alt + 1 ¡
Right Alt + 2 ²
Right Alt + 3 ³
Right Alt + 4 ¤
Right Alt + 5 €
Right Alt + 6 1/4
Right Alt + 7 1/2
Right Alt + 8 3/4
Right Alt + 9 '
Right Alt + 0 '
Right Alt + - ¥
Right Alt + = ×
Right Alt + Q ä
Right Alt + W å
Right Alt + E é
Right Alt + R (r)
Right Alt + T þ
Right Alt + Y ü
Right Alt + U ú
Right Alt + I í
Right Alt + O ó
Right Alt + P ö
Right Alt + [ "
Right Alt + ] "
Right Alt + \ ¬
Right Alt + A á
Right Alt + S ß
Right Alt + D ð
Right Alt + L ø
Right Alt + ; ¶
Right Alt + ' ´
Right Alt + Z æ
Right Alt + C (c)
Right Alt + N ñ
Right Alt + M µ
Right Alt + , ç
Right Alt + / ¿
Shift + Right Alt + 1 ¹
Shift + Right Alt + 4 £
Shift + Right Alt + = ÷
Shift + Right Alt + Q Ä
Shift + Right Alt + W Å
Shift + Right Alt + E É
Shift + Right Alt + T Þ
Shift + Right Alt + Y Ü
Shift + Right Alt + U Ú
Shift + Right Alt + I Í
Shift + Right Alt + O Ó
Shift + Right Alt + P Ö
Shift + Right Alt + \ ¦
Shift + Right Alt + A Á
Shift + Right Alt + S §
Shift + Right Alt + D Ð
Shift + Right Alt + L Ø
Shift + Right Alt + ; °
Shift + Right Alt + ' ¨
Shift + Right Alt + Z Æ
Shift + Right Alt + C ¢
Shift + Right Alt + N Ñ
Shift + Right Alt + , Ç

The Dead Keys
The dead keys are the apostrophe ('), quotation mark ("), accent grave (`), tilde (~), and caret (^). If these are pressed the system waits for the next key. If it is in the list below then it enters the symbol character else it enters both keys separately. These work with uppercase where appropriate. Press Space to insert the dead character.
Key Description
' then C Ç
' then e é
' then y ý
' then u ú
' then i í
' then o ó
' then a á
" then e ë
" then u ü
" then i ï
" then o ö
" then a ä
` then e è
` then u ù
` then i ì
` then o ò
~ then o õ
~ then n ñ
^ then e ê
^ then u û
^ then i î
^ then o ô
^ then a â

These next two work on all keyboards
Alt + Character Code
Holding down alt and pressing the character code on the numeric keypad will enter that character. The keyboard language in use must support entering that character. If your keyboard supports it the code is shown on the right hand side of the status bar in Character Map else this section of the status bar is empty. The status bar us also empty for characters with well known keys, like the letters A to Z.
However there is two ways of entering codes. The point to remember here that the characters are the same for the first 127 codes. The difference is if the first number typed is a zero of not. If it is then the code will insert the character from the current character set else it will insert a character from the OEM character set. Codes over 255 enter the Unicode character and are in decimal. Characters entered are converted to OEM for Dos applications and either ANSI or Unicode depending on the Windows' application. See Converting Between Decimal and Hexadecimal.
E.G., Alt + 0 then 6 then 5 then release Alt enters the letter A.

Hex To Unicode IME
In programs based on the Rich Edit 3 control, such as Wordpad, enter a Unicode number in hexadecimal format into the document then press Alt + X. This will convert the number typed into the Unicode character. Select a character and press Alt + X to convert that character into it's Unicode number. The code is shown on the left hand side of the status bar in Character Map in the form U + <hexadecimal code>, e.g., U + 0061 for the letter a.
Selecting letters A to E will result in it being considered a hexadecimal number and it will convert to the Unicode characters (which are things like form feed and the enter key).
Comment: THANK YOU SO MUCH!! I''m very surprised you decided to type all of this out for my small brain, but this will help me with many things. The US International layout is exactly what I was looking for, so now I'm going to use it.
Comment: I started typing in the late 90s and finished in late 2000s. You can get the full docs here https://onedrive.live.com/?id=E2F0CE17A268A4FA%21121&cid=E2F0CE17A268A4FA it called Shortcut Keys and Key Modifiers.hta
Answer: My default key layout is US English, but I frequently type in 2 other languages, both of which have their own special characters and other quirks.
After trying AutoHotKey and a couple of other solutions I've found that by far the easiest way is to just add the other two layouts and switch layout with key combination when I need specialties US English layout doesn't offer.
Comment: Yeah, that's how I have it setup now, but I'd still prefer to have them all at a the press of a key, and not have to switch keyboard layouts. (Yes I know shortcuts exist!)
Comment: LOL yes, I can sympathize - sometimes it's a serious pain in the donkey :-D
Answer: I use a UK keyboard but I regularly use accented characters, and sometimes even Greek letters and mathematical symbols. This is done with a third-party piece of software that implements a Compose key.
Press the Compose key, and then two characters on the keyboard that together look like the target symbol.
For example
' a  =>  á
" a  =>  ü
o /  =>  ø
* s  =>  σ
> =  =>  ≥

This is different from using a keyboard layout that implements "dead keys", because none of the keys are dead. I don't have to do anything special to use the apostrophe keys (' ", etc.) normally, since the special composition only comes in to play after the Compose key is pressed.
On my keyboard I use the otherwise spare AltGr key, but typically you can choose to map any of the modifier keys (I believe Right Alt is a favourite on keyboards without AltGr).
I've been using AllChars for years, but it's gradually becoming more cranky as Windows 10 evolves. A nice alternative seems to be WinCompose.
Comment: Alt Gr and Right Alt are identical electronically differing only in what is printed on the key.
Comment: @user1292580 if you didn't know that, and didn't have an AltGr key, you'd probably want to have an alternative key suggested. I made that suggestion to try and make things easy
Answer: The Spanish/Latin American keyboard layout is mostly the US one, with some extra keys/combinations. Variations of that is what I have on my machines here in Chile, using it to write mostly English and (obviously) a load of Spanish and the occasional German. Plus is that I've the Spanish characters (ñ, ü, ¡, á) at hand, and others (like German ß and French ô or è) are also available.


How is the price of BEP-20 determined?

Question: If I understand correctly after you create your BEP-20 token you should add liquidity and it will determine the base price of new token but what's happening next? How is the price determined afterwards when token is being transfered by many people?
Also how can you make your token in your wallet available for trade on demand by others?
Like if the token supply is 1000, and all 1000 is on my wallet then how can one buy this?
Sorry if these questions are stupid but I am new to this.
Comment: Prices are determined by the free market https://ethereum.stackexchange.com/a/37586.
Comment: @Ismael and how do I put my token for sale?
Comment: You can create your own contract or use an existing exchange, like uniswap or sushiswap.
Comment: I'm asking the same question myself, have you found out how to do it.
Answer: Instead of keeping the tokens in your wallet, you send them to a liquidity pool such as pancakeswap. You set the price during this process and pair with another coin such as ethereum or Binance (BNB). So if anyone wants to buy your token they go directly to the pool exchange (pancakeswap). The pool determines the price based on supply and demand in comparison to the paired coin.
Answer: Yes but Is someone sends the token say, 10000 to the liquidity pool and sets the price. In swap only 10000 are available for people to buy. How can people buy more than that. Do you need to add liquidity again or can you sell it from your wallet directly without putting it into the liquidity pool and putting equal amount of other currency as liquidity.

How is the price of BEP-20 determined?


Attestation on fork or reorg

Question: Suppose a validator needs to do attestation for slot N. It sends the attestation but later discovers that there was a fork or reorg on slot N-1 (and that he attested for the wrong fork). Should he produce another attestation for the correct fork?
Answer: No, a validator should never produce two concurrent attestations to avoid being slashed for Double vote.
Here is the condition that would slash a double vote where the first vote is data_1 and the second vote is data_2:
        # Double vote
        (data_1 != data_2 and data_1.target.epoch == data_2.target.epoch)

As you can see, a validator should not make two different attestations for the same epoch.

Attestation on fork or reorg


Dirac spinor in the chiral basis

Question: In the chiral basis, the gamma matrices take the form
$$
\gamma^0=\begin{bmatrix}0 & 1 \\ 1 & 0\end{bmatrix}, \quad \gamma^j=\begin{bmatrix}0 & -\sigma^j \\ \sigma^j & 0\end{bmatrix}
$$
and therefore one can calculate what the left and right projectors look like:
$$
P_R=\begin{bmatrix}1 & 0 \\ 0 & 0\end{bmatrix}, \quad P_L=\begin{bmatrix}0 & 0 \\ 0 & 1\end{bmatrix}.
$$
Given a Dirac spinor with components $\psi=(\psi_1,\psi_2,\psi_3,\psi_4)^T$, it is pretty clear that the Weyl spinors should become
$$
\psi_R:=P_R\psi=\begin{pmatrix}\psi_1  \\ \psi_2 \\ 0 \\ 0\end{pmatrix}, \quad \psi_L:=P_L\psi=\begin{pmatrix}0  \\ 0 \\ \psi_3 \\ \psi_4\end{pmatrix}
$$
and one can reconstruct the spinor by summing over both of them, as $\psi=\psi_R+\psi_L$. I've been told however that in this basis we can decompose the Dirac spinor in terms of the Weyl spinors as
$$
\psi=\begin{bmatrix}\psi_R  \\ \psi_L \end{bmatrix}.
$$
This can't be possinle, if $\psi_R$ and $\psi_L$ are the objects with four components defined above. So it is probably a notational issue; who are these $\psi_R,\psi_R$ and what is their relation with $P_R\psi, P_L\psi$?
Answer: The projectors $P_R, P_L$ project $\psi \in \mathcal{H}\cong \mathbb{R}^4$ onto the right- and left-handed sectors of the representation of the Lorentz algebra, which are each a two-dimensional vector space, hence (locally) isomorphic to $\mathbb{R}^2$.
What "sum" is meant here is the direct sum $\oplus$:
$$\begin{pmatrix} \psi_1 \\ \psi_2 \end{pmatrix} \oplus \begin{pmatrix} \psi_3 \\ \psi_4 \end{pmatrix} = \begin{pmatrix} \psi_1 \\ \psi_2 \\ \psi_3 \\ \psi_4 \end{pmatrix}.$$
You correctly observed that the projector operators drop the two entries not in the projected space, so $P_L \mathcal{H} \cong \mathbb{R}^2$, likewise for $P_R \mathcal{H}$. So the statement "$\psi = \psi_1 + \psi_2$" really means
$$\mathcal{H} \cong P_L \mathcal{H} \oplus P_R \mathcal{H}.$$
To answer your last question, then, $\psi_R$ and $\psi_L$ are the members of $\mathbb{R}^2$ which can be identified (via isomorphism) to the images of the projections of $\mathcal{H}$.
Comment: Thank you for your answer, I did suspect it was something like that. Unfortunately the exposure I had on this topic was quite mathematically sloppy and I feel too many details were glossed over.
Comment: Glad it helps. My favorite exposition of this topic is chapter 10 in Schwartz's Quantum Field Theory and the Standard Model. He starts with representations of the Lorentz group, which motivates this decomposition very naturally (chapter 10.2). He's also not afraid to flash mathematical terminology, which makes it easy to google for extra context.

Dirac spinor in the chiral basis


What info to log/store about a user login?

Question: Currently I am saving LastLoginAt, LastActionAt, LastLogoutAt, and LastLoginFromIPAddress. I am not so sure about the value of logging/saving details of logouts and IP addresses, as I am not sure of what use they would actually be. What is the "best" practice here when it comes to saving info about user logins?
Answer: You didn't provide any specifics about your app, but you generally should log much more than you're currently storing. See this logging Cheat Sheet for more details.
Generally: if you only store info about "last" actions, you have very little to work with if you need to use any of that data at a later date.
Even for a "simple" web app I've found it extremely useful to store a full log of login/logout actions, with associated IP addresses and even the User-Agent string (if it's a web app).
You should probably also log invalid login attempts (user_id, time, ip_address) to do some sort of rate limiting and/or password brute-forcing detection.
Simple example: if a user contacts you about his account being "hacked" (password was stolen or guessed), you need to have a full log of logins to do any meaningful analysis.
Comment: It is a web app for consumers. Should I do all this logging in a database or a file?
Comment: That's a very broad question with no clear answer. If you want you can provide much more detail and ask a question on http://stackoverflow.com/.


The rationale behind "She is coming back next Wednesday" without "on"

Question: I have seen posts on this forum about how She is coming back next Wednesday. shouldn't have the preposition on before next Wednesday. What I want to know is whether anyone here can help provide the rationale behind this grammar rule? I would like to teach my ESL students in our next class about not having to use on before all of this Wednesday, that Wednesday, every Wednesday, last Wednesday etc., and I'd like to provide them an explanation instead of asking them to memorize it. Any help will be appreciated.
Comment: Does this answer your question? [Is it common to omit a preposition (in / on / of) before "the month (year / week /day) when they are used adjectively and adverbially?](https://english.stackexchange.com/questions/111217/is-it-common-to-omit-a-preposition-in-on-of-before-the-month-year-week)
Comment: The _fluffy_ excerpt mentioned above is missing a link; it is [Is it common to omit a preposition (in / on / of) before the month year week?](https://english.stackexchange.com/questions/111217/is-it-common-to-omit-a-preposition-in-on-of-before-the-month-year-week/111232#111232). It is from the prestigious 'A Comprehensive Grammar of the English Language' (Quirk et al); the reason behind the rule (and note that you ask for the rule, not the rationale, which is probably intractable ... unless someone finds a published article) is not mentioned. The quote contains a lot more rules to learn.
Comment: Does this answer your question? [What happens to an adverbial/preposition phrase such as "on Monday" when you remove the proposition "on"?](https://english.stackexchange.com/questions/478034/what-happens-to-an-adverbial-preposition-phrase-such-as-on-monday-when-you-rem)
Comment: @EdwinAshworth Thanks for your suggestion, yet it doesn't answer my question. The other posts talks about "Monday vs on Monday" while mine "on next Wednesday vs next Wednesday".
Comment: @fluffy, at [](), gives the rule: 'In the examples you have given, it is fine to use a preposition. There are cases when prepositions must be omitted and when omission is optional:

prepositions of time are omitted before the words: last, next, this, that, some, every (We met last month. We meet every day.)'
Comment: @EdwinAshworth Like I've mentioned I know we need it omitted, but I'd like to know the grammar rule that governs it, instead of just learning that we have to omit it. Thanks.
Comment: Certainly a duplicate of ['next Monday', or 'on next Monday'?](https://english.stackexchange.com/questions/50283/next-monday-or-on-next-monday/50285#50285). The 'grammar rule' is as stated above. The reason for the rule? I'd say it's just the way the language has evolved. FumbleFingers offers a guess, that 'on' and 'next' partially fulfil an equivalent grammatical role, and we tend to drop prepositions in temporal expressions where possible ('I'll see you Monday').
Comment: @EdwinAshworth I am not too sure about why there is a urgent need that my question be regarded as duplicated when it clearly is not, and be closed, especially when it hasn't been answered. When I mean by learning a rule that governs is, I am hoping to hear of the answer of something like "because xxx is the xxx so we don't need a preposition" or something along that line. Your way to explain it has been heard, and it would be deeply appreciated if we could together leave this question to see if other experts in the language might be able to provide us with a way to really explain it. Thanks.
Comment: @MissJoey: I don't know what kind of rule you are looking for. The rule that Edwin quotes above **is** the grammar rule that governs this.
Answer: It is a reasonable desire to find the rationale behind a grammatical rule.
It's what linguists want to do. It's what teachers and students would like to know.
Unfortunately, there are problems. One is that many rules don't have a rationale. They just are.
Also, they are very rarely stated specifically.
Even when they are, they're quite often wrong.
In this specific case, there can't be a hard rule, because dropping on with these phrases is an optional phenomenon. That is, the speaker may do it, or may not, at their sole discretion, depending on how they're feeling at the moment. Nobody can tell them whether to use it or not.
It is always allowed to use on with dates. As noted, determiners like next, last, this, that, some, every can precede the dates after on, and the on may be omitted. This is also true of any noun phrase that refers to a specific date:

He returned home (on) the same day she left.
I'm supposed to meet him (on) some day next month.

But it doesn't work with indefinite noun phrases denoting dates:

I like  to run a on day like this.
*I like to run a day like this. (asterisk means ungrammatical)

As for the rationale, it's like a lot of deletions of small words in English.
Complementizer that, infinitive to, wh+be in Whiz-deletion,  Conversational deletion, and so on. These are all meaningless words that guide the listener to the structures. As such, they are predictable.
When they're talking fast, with somebody they know well, people tend to leave things out. Every preposition in English is an unstressed syllable. English is a stress-timed language, in which unstressed syllables are reduced and jammed into the time between stressed syllables. So English speakers tend to delete predictable, unnecessary, unstressed syllables. A lot of these are prepositions. That's all, really.
Comment: This answer asserts that "on next Monday" is correct idiomatic standard English. [Other answers](https://english.stackexchange.com/questions/50283/next-monday-or-on-next-monday) and [a reference](https://www.englishclub.com/grammar/prepositions-at-in-on-time.htm) contradict this. I agree there are time constructions in which "on" is optional, but is this one of them?
Comment: It occurs to me you might think the other answers and the reference are all wrong. Which they might be. But I don't remember hearing or reading "on next Monday" in American or British English (though I think I recall hearing quaint expressions such as "on Monday next").
Comment: _She's coming back on next Monday, not next Tuesday._ I express no opinion of the reference or other answers. The point is that individual use of optional rules varies widely, to the point where one simply cannot say that any such sentence is or is not "correct idiomatic standard English", even if that phrase were not a contradiction in terms. Optional rules are **optional**, and just about every rule is optional under some situations.
Comment: The word "on" still seems out of place in that example. The world won't come to an end due to a stray preposition like that, and the main purpose of language, which is communication, is satisfied. In that sense spelling, punctuation, and so forth also are optional up to the point where communication fails. It still seems useful to me to recommend to ESL students that they say, "She's coming back next Monday, not next Tuesday."
Comment: Spelling and punctuation are optional in any case; they're not part of language or grammar. Orthography (written language) is technology and is no more relevant to sentence construction than are manual auto transmissions.


How to make physical simulation of unmixable fluids (like oil and water) in any container

Question: I wish to make an animation of pouring water over oil or vice versa. In physical simulation, how do I make oil thicker than water and make both liquids behave realistically when stirred and left to settle?
Comment: Have a look at the [molecular addon](https://www.youtube.com/watch?v=r3-PSEijh_I)
Comment: Thanks, @sambler. I have looked at few videos on molecular addon. Thanks for mentioning the addon.
Answer: The fluid simulation engine that ships with Blender isn't capable of mixing two fluids.
They would require two separate domains, with different parameters, being baked at the same time and reading the other domain's status frame-by-frame as input for themselves. Unfortunately, this kind of "simultaneous bake" isn't possible.
Comment: That is useful to know and I'll keep that in mind. Thanks.


Changing settings on iPad Pro selfie camera? (2018 11 inch model)

Question: Apparently the selfie camera (FaceTime HD) can operate in both 30 FPS and 60 FPS modes. I haven't found a way to change it. Is there one?
Answer: To adjust the refresh rate and resolution of the selfie camera, you also have to adjust the video recording options of the main shooter too. Apple does not let you change the settings independently of one another.
Go to: Settings>Camera>Record Video> "1080p at 60FPS" or "1080p at 30FPS".
You should see the results immediately in the viewfinder.
Comment: Thanks! Do you know if that also applies if the main camera is in a 4K video mode?
Comment: If the camera supports 4k, I believe along with the two other 1080p options it will also list the 4k options too.


Where to find participants for User Research Interviews?

Question: If you are not able to source users through the client or pay a recruitment firm, what are the alternatives to find participants for User Research Interviews? Do you search for participants through social media and approach end users through there?
Answer: If you already got your product set up (e.g. website, app)you can use the following methods

chat bot (prompt for user feedback after the user engages)
using existing mailing list

you can also use the following screens with a banner that leads to a user research sign up page.

Confirmation screen
404 page
footer of your website

If you haven't got anything set up you can use guerilla testing method where you approach people in public areas like cafes.
Comment: What also often happens is that company's look within their own circle (e.g. friends, family of employees) that might fit the criteria of the desired participant. Of course the outcome of that is incredibly dependant on how 'difficult' it is to find a certain profile. A 'person interested in cars' is much easier to find than 'person who works in risk in the financial world'.
Answer: Depending on what niche you are working in, you can try out reddit. I sent messages to individuals who answered my question on reddit to check if they were interested in being a part of the interview. Slack channels are another way to reach out to potential users. Hope this helps!
Answer: Start with a plan. You should recruit participants who represent your target group/end users. If you don't have the funds to use a recruitment agency, you must recruit participants yourself. The best way to do that depends on the project. Using your network or posting on social media like (Facebook, Twitter, LinkedIn, Reddit), can be efficient if your participants are people who are not too far from your own social circle. Also outside there are many slack groups that can give you the ability to find some participants.
How closely related your participants can be to you again depends on your project, but in this case, you have less risk of bias if your participants don't know you personally.
Also, if you need to recruit user groups that are hard to reach, then you can use interest groups or internet forums where you think people from your target group might be active.
Answer: Three options:

Existing Users - you can get your sales and marketing teams on board to help engage these users.

Potential Customers / Users - . You can find them hanging out on online communities on Facebook, Linkedin, and Reddit. Finding communities with your ideal audience is a breeze these days. If you did a rough Google search for: <name of community + forum>; that is, <product designers + Slack>, you'd discover several online groups with this target audience.

Competitors' Users - When you pay a quick visit to any company's website, you'd find customer success stories plus testimonials that can serve as secondary user research data. Also, social media platforms like Twitter are good sources of real-time feedback from competitors' users.

Source: https://www.getepiphany.com/post/recruit-users-for-user-research


Reverting to old iTunes, converting .itl file

Question: I have an iTunes Library.itl that was used with iTunes 126.96.36.199.  Through the sorcery that is Retroactive, I now have iTunes 11.4 once again on my Catalina-based computer.  However, none of the Playlists or other data survived because my .itl is newer.  (On first run, it noted I had a newer file and asked if I wanted to download iTunes.)  Does anyone know of a way that I can allow the iTunes 11.4 to use the data from the later file?  (The real question is why iTunes stores this particular data in a closed format, but...Apple.)
Answer: This is a bit of an experiment I can't really test, so make sure you keep safety copies of everything.
Prior to iTunes 12.3, you could rebuild an .itl file from the associated xml, by just breaking it - this would force a rebuild.
In Terminal, type touch ~/Desktop/iTunes\ Library.itl
This will create an empty file on the desktop with the correct name.
With iTunes quit, move it to your ~/Music/iTunes folder, replacing the original & launch iTunes. It should notice the file is broken & rebuild it.
Using a similar method in the past this would sometimes lose some album artwork & I can't remember whether playlists & play counts carry over this way, but the basic library should be good to go.
Comment: THIS.  WORKED.  I haven't dug in to make sure everything's available, but Playlists I haven't seen for years (like my mother's visitation and my wedding) reformed, it culled through the Album Artwork and it's currently determining the gapless information.  I should note - I was able to restore the iTunes folder from my Time Machine, so everything was just as I left it last, which may have helped with the rebuild.  Took about 1/2 hour, but I have 180+GB of music.  THANK YOU!
Comment: I should add - after reviewing further - much of the information has been restored.  Album Artwork is only showing up for some discs (and there were discs I had assigned custom artwork), but it appears playlists (auto and manual), play counts, even my personal ratings, all are intact.


Can a fan cool objects better in a less dense atmosphere?

Question: Assuming constant fan power, how would atmospheric pressure/density affect the cooling rate of objects being cooled by a fan?  Like in a lower pressure atmosphere, would a fan be able to cool objects more quickly because it could blow less dense air at a faster speed, would it cancel out and be the same or would the cooling rate be lower under less atmospheric pressure/density?
Comment: Ask yourself this question:  What would happen if the air density were zero?
Comment: If the air tight container has vacuum in it (zero density), the fan blades will just spin, but will not push any air around, so the fan won't contribute to any cooling whatsoever.
Comment: I'll add to Chester Miller's comment.  Please provide more information.  Is the object outdoors or indoors?  Regarding heat transfer, you will normally find that convection, conduction, and radiation, are ALL happening at the same time.  If  you don't specify more constraints on the problem, you will not get a reasonable answer.
Comment: Well I'm thinking of an object that's inside an air tight container.
Comment: Right, and I can imagine that the cooling ability of a fan approaches zero as the density of air does, but what I was wondering was as the density of air approaches zero, at what rate does the cooling decrease?  Would it just be a linear decrease, or is it otherwise?  Like if the mass of air being blown is lower by a certain proportion, but the velocity is higher by the square root (because power of the fan is constant), and the cooling rate would decrease by the square root of the air density decrease.
Answer: This can be understood using heat transfer formulae $$dQ=h \cdot A \cdot (T_{air}-T_{solid})$$ where heat transfer coefficient is an empirical function of velocity and density. So to remove heat, one need to either increase velocity or increase density. In your question, you increase velocity and reduce density, so the trend is uncertain.
Comment: Increase velocity and reduce "density"... not speed.
Answer: No, it can't.
Just consider this: Some unmanned aircraft have pressurized compartments in their fuselage. Sounds strange? If no pilot is on board, why bother with pressurization?
The low air density at altitude would not be sufficient to cool the electronics, so a pressurized electronics compartment had to be added. If you keep the fan power constant, it would only increase flow speed by the square root of the density difference, leaving you with a reduced cooling performance.
Comment: That does answer my question.  I have to ask, does this mean that with the mass of air being blown proportionally decreasing with pressure and velocity increasing proportional to the square root, does that mean the effectiveness of the fan approaches zero but does so by the square root of the air pressure?
Comment: Define effectiveness of the fan first! If you adjust the fan speed to the flow speed, its efficiency will remain unchanged.


Knob and Tube Wiring with AFCI

Question: We have a rental house that still has some knob and tube wiring. We did not know about the knob and tube wiring when we bought the house 18 years ago. We didn't know such a thing existed but remember the seller telling us her father was an electrician and updated some of the wiring. Some of the knob and tube has been removed but there is still some in the house. Last year we hired an electrician to remove it but because it is an old house he wasn't sure if he could get all of it out. It ended up he installed AFCI instead and said we should be safe. There is some lose insulation in the attic over the wire. Should we hire someone else to remove the knob and tube wire? Is the AFCI enough of a safety feature that we should not have to remove the knob and tube? thanks for your help!
Comment: @TheEvilGreebo sounds more like he's the landlord.  "Rental house......we bought 18 years ago".  Tenants also rarely refer to "a seller".
Comment: Please [merge your guest and registered accounts](/help/merging-accounts), which will allow you to [edit](/help/privileges/create-posts), [comment on](/help/privileges/comment) any of your posts and [accept an answer](/help/someone-answers) on your question. Thanks, and welcome to the site!
Comment: Well your first question should be, "Will my landlord be ok with this?"  The next question is - is the k&t actually IN USE?  Or is it just old K&T that's not connected to anything?
Comment: @TheEvilGreebo They own it...they're not renting.
Comment: Ah now I get it. Totally misread "we have a rental house"  - ok then just go with "is the k&T still in use"?
Answer: I maintain 100 year old electrical systems.
Knob & tube is legit. Notice that most of the people telling you it's bad are people who stand to profit from your worry.
Cities and the NFPA are not nearly as worried.
AFCI is a superb way to protect any wiring you're worried about.  I recommend it for aluminum wiring, backstab connections, you name it.  It will prevent arcing/sparking of the sort which makes connections hot and starts fires, not that K&T has a problem with that. Like most electrical work of that age, K&T splices are wildly overbuilt by modern standards: wrapped, soldered and insulated often with two kinds of tape. We use backstabs.
People of that age didn't have our tech, but they were serious about their craft. Nobody had to tell them not to eat Tide pods.
Add GFCI protection to stop even small current leakage from wet wires,  and you are safe as can be. You can even put 3-prong sockets on those receptacles.
One more thing. There was a concern that blown-in insulation packing around knob and tube wire would cause it to overheat. However, the states of Oregon and Washington did an extensive survey on this, and found it to be false. As such, they liberalized their laws to permit blown insulation around knob and tube.
Comment: See also https://diy.stackexchange.com/questions/20/should-old-knob-and-tube-wiring-be-replaced/20279#20279
Answer: Well, look at it this way, knob and tube wiring is a wiring method that is almost 100 years old. It was most probably installed when the house was originally built. The house has not burned down yet. Hence, it must be a pretty sound wiring method.
If the loose insulation were to get wet between conductors it could begin to heat up. If your roof is sound and the attic is dry, then you are good.
Normally, the only reason to update wiring is because you are doing a major remodel and opening up the walls anyway.
The AFCI breakers add a layer of protection to the older system. I wouldn't worry about it.
Good luck!
Comment: Thanks so much for your advice. It was actually a fireman and registered electrician that did the work but I wanted to check with others because it is a rental property so I feel more responsible for others safety than my own. We have also been pricing around for new insurance and have not found any regular companies (like Metlife) that will insure us. He also put in GFCI.
Answer: Mixed K&T and new is pretty much the rule, not the exception.  It's just too hard to change the switch legs to light fixtures, and there's essentially no point doing so.  See https://diy.stackexchange.com/a/20279/5960
Some insurance companies will insure if "90%" of the K&T is gone.  It's unclear if that's 90% of the wire length, 90% of the circuits, 90% of the load or what.  It's probably unclear because they have no clue!
Answer: Early AFCI devices had troubles on "shared neutral" systems like your K&T.  Recent ones, pretty much have that figured out.
AFCI devices on K&T circuits protect against the same types of issues they do on modern circuits.  The K&T is likely fine itself, but a spark could develop on an outlet box edge or if the wire is physically damaged.
So AFCI on K&T: a good idea.

Knob and Tube Wiring with AFCI


How do I know if the given signal is discrete?

Question: If I am given an expression of a signal then how do I know if it is a discrete signal or not?
If this signal is given how do I know if it's a discrete or continuous?
$$x(n) = e^{j (n \pi/2 + \pi/8) } $$
Answer: Fortunately, one typically does not receive signals from strangers in real life. One knows because one is working on an application.
A discrete signal can be equivalent to a continuous signal so you need a set of assumptions tying the two together, like a Nyquist sampling criteria and then you need to test for equivalence under those assumptions.
A function that only exists at discrete points( like time points) and there is no meaningful notion of intermediate values between those points is discrete. Some financial time series are like that.  Arrival times of a Poisson process is another discrete function.  If intermediate values on a continuous range are meaningful, a continuous function is likely.
Answer: In general you cannot know, but in DSP (and in other fields too) there's a convention that $n$ denotes a natural number, and not a real number. So the given signal $x(n)$ almost surely denotes a discrete-time (-space, etc.) signal. Some authors, but by far not all, use the additional convention that brackets denote sequences, and parentheses denote functions (of continuous variables). So those authors would have written $x[n]=\ldots$, but usually the variable $n$ is sufficient to make clear that we're talking about a sequence defined for integer arguments, and not about a function of a continuous variable.
Answer: Two sides could  be checked: sampling and quantization, two sides of discretization. Discrete somehow refers to a grouping, a set of things that are distinct. Continuous refer to very close things. This does not seen very precise mathematically, let us be more specific.
A signal $s(t)$ can be discrete/continuous either in the ordinal  variable $t$ (a variable that exists outside $s$, like the time, or a space measure), or in the different values $s$ can take across all $t$. To me, a truly discrete signal should be discrete in both aspects; a regularly-spaced signal $s[nT]$, $T>0$ where the values are coded on 8-bits (taking at most 256 different values) is fully discrete. On the other side, the signal $t\to t\sin t$, $t\in \mathbb{R}$ is continuous, and can take any given value in $\mathbb{R}$.
How to draw a line between them is complicated.  In many textbook  cases, discrete refers only to the ordinal variable. Then, you know than one can take frequency as the ordinal variable, and talk about a discrete spectrum. In that case, I'd consider a data discrete if for any two different ordinal locations $t_k$ and $t_l$ where the signal is defined, the difference $|t_k-t_l|$ is always above some predefined threshold. A similar version can be used on the amplitudes, and looking at closed finite intervals.
In your case, where $n$ is likely to be an integer, the difference $|(n_kπ/2+π/8)- (n_lπ/2+π/8)|$ is always greater than a non-zero positive constant. Now, what happens to the values: if $n$ is an integer, then:
$$x(n) = e^{j (n \pi/2)}  e^{j\pi/8) } = (e^{j  \pi/2})^n  e^{j\pi/8} = j^n e^{j\pi/8}$$
so it can take only four different values (or 2 bits): $0$, $\pm j e^{j\pi/8}$ or $e^{j\pi/8}$, so it is  discrete in both aspects.


I can't turn off "Easy Mode" on Galaxy On5 and there are missing options in the "Settings" Menu

Question: I really need help here. I accidentally turned on my sister's "Ultra Power Save Mode" and, when I had realized I had done this, I turned it off. When the phone rebooted on again, it asked me what kind of set up I wanted, and me not knowing what it was talking about, selected one of the options and now it's stuck on "Easy Mode", but the apps are limited and there are missing options from the "SETTINGS" menu. I'm at my wits end and I'm afraid I might have to buy her a new phone. If anyone could answer me, that'd be amazingly helpful...
Answer: From Samsung Galaxy S5: How to Disable Easy Mode in Android 4.4.2 Kitkat:

Method #1: From the notifications panel

Swipe down the top of the screen to open up the notifications panel.
Tap the gear(1) to go to the easy settings menu.
In Easy settings, tap Easy mode .
Tap Standard mode to select it.
Tap Done button.

The easy mode will be disabled and the standard mode will be applied in your phone.

(1) Added emphasises due to original article has a picture instead of text.

Method #2:
From the Easy settings shortcut in Home screen
  By default, you can find the easy settings in the Home screen in easy mode as an app and you can use it to access the easy settings menu to disable easy mode. See the following steps to disable easy mode:
  From the main Home screen, swipe the screen from right to the left until you see the Easy settings shortcut/icon  and then tap it to go to the easy settings menu.

Tap Easy mode .
Tap Standard mode to select it.
Tap Done button.
  The easy mode will be disabled and the standard mode will be applied in your phone.

If in the easy mode you'll be provided with a simpler layout and the easy settings menu, then in the standard mode you'll be provided with a conventional layout and more complex settings menu. Also, in the standard mode, you can find and use all features owned by this phone unless you disable them.


Is there a way to get Cache Hit/Miss ratios for block devices in Linux?

Question: Is it possible to see in Linux how many read and write requests from user space end up causing cache hits and misses for block devices?
Answer: You can develop your own SystemTap script. You need to account the following two subsystems:

VFS: this represents all I/O requests before the Buffer cache (i.e. absolutely every I/O request); review the "vfs.read", "vfs.write" and the "kernel.function("vfs_*")" probes; you need to filter out the block devices you want to monitor by their respective major+minor numbers.
Block: this represents all I/O requests sent to the block devices before the I/O scheduler (which also does merge + reorder of the I/O requests); here we know which requests were missed by the Buffer cache; review the "ioblock.request" probe.

SystemTap development takes some time to learn. If you are a moderate developer and have good knowledge in Linux, you should be done in 3-4 days. Yes, it takes time to learn, but you'll be very happy with the results - SystemTap gives you the opportunity to (safely) put probes in almost any place in the Linux kernel.
Note that your kernel must have support for loading and unloading of kernel modules. Most stock kernels nowadays support this. You'll also need to install the debug symbols for your kernel. For my Ubuntu system, this was as easy as downloading a several hundred MB .deb file, which the Ubuntu kernel development team compiled for me. This is explained at the SystemtapOnUbuntu Wiki page, for example.
P.S. Take the SystemTap approach only if you have no other solution, because it's a totally new framework which you have to learn, and that costs time/money and sometimes frustration.
Comment: +1 nice & clean explanation. thank you, i'll checkout systemtap too.
Comment: [A SystemTap script for this](https://sourceware.org/systemtap/wiki/WSCacheHitRate) is in their wiki.
Answer: I went ahead and wrote an stap script for this. There is one on the systemtap wiki, but it doesn't appear to be correct. In basic testing, this appears pretty accurate but YMMV.
#! /usr/bin/env stap
global total_bytes, disk_bytes, counter

probe vfs.read.return {
  if (bytes_read>0) {
    if (devname=="N/A") {
    } else {
      total_bytes += bytes_read
    }
  }
}
probe ioblock.request
{
    if (rw == 0 && size > 0)
    {
        if (devname=="N/A") {
        } else {
          disk_bytes += size
        }
    }

}

# print VFS hits and misses every 5 second, plus the hit rate in %
probe timer.s(5) {
    if (counter%15 == 0) {
        printf ("\n%18s %18s %10s %10s\n",
            "Cache Reads (KB)", "Disk Reads (KB)", "Miss Rate", "Hit Rate")
    }
    cache_bytes = total_bytes - disk_bytes
    if (cache_bytes < 0)
      cache_bytes = 0
    counter++
    hitrate =  10000 * cache_bytes / (cache_bytes+disk_bytes)
    missrate = 10000 * disk_bytes / (cache_bytes+disk_bytes)
    printf ("%18d %18d %6d.%02d%% %6d.%02d%%\n",
        cache_bytes/1024, disk_bytes/1024,
        missrate/100, missrate%100, hitrate/100, hitrate%100)
    total_bytes = 0
    disk_bytes = 0
}

Comment: Awesome! I added a little average cache use stat to print out when you close it: http://pastie.org/1845683
Comment: I have copy/paste your code to run it, by the following error occured, `semantic error: unable to find member 'bi_size' for struct bio (alternatives: bi_next bi_bdev bi_flags bi_rw bi_iter bi_phys_segments bi_seg_front_size bi_seg_back_size bi_remaining bi_end_io bi_private bi_ioc bi_css bi_integrity bi_vcnt bi_max_vecs bi_cnt bi_io_vec bi_pool bi_inline_vecs): operator '->' at /usr/share/systemtap/tapset/linux/ioblock.stp:113:20
        source:         size = $bio->bi_size
                                   ^ Pass 2: analysis failed.  [man error::pass2]` can you help ?
Answer: /proc/slabinfo is a good start, but doesn't give you quite the information you're looking for (don't be fooled by the hit/miss percentages on systems with multiple cores and stats enabled; those are something else).  As far as I know, there's not a way to pull that particular information out of the kernel, though it shouldn't be terribly difficult to write up a bit of code to do.
Edit: http://www.kernel.org/doc/man-pages/online/pages/man5/slabinfo.5.html
Answer: Now there's the cachestat utility from perf-tools package.
The author also lists some (possibly cruder) alternatives people use:

A) Study the page cache miss rate by using iostat(1) to monitor disk reads, and assume these are cache misses, and not, for example, O_DIRECT. The miss rate is usually a more important metric than the ratio anyway, since misses are proportional to application pain. Also use free(1) to see the cache sizes.
B) Drop the page cache (echo 1 > /proc/sys/vm/drop_caches), and measure how much performance gets worse! I love the use of a negative experiment, but this is of course a painful way to shed some light on cache usage.
C) Use sar(1) and study minor and major faults. I don't think this works (eg, regular I/O).
D) Use the cache-hit-rate.stp SystemTap script, which is number two in an Internet search for Linux page cache hit ratio. It instruments cache access high in the stack, in the VFS interface, so that reads to any file system or storage device can be seen. Cache misses are measured via their disk I/O. This also misses some workload types (some are mentioned in "Lessons" on that page), and calls ratios "rates".
Answer: If you are interested in the IO hit/miss ratio of a specific process, a simple but very effective approach is to read the /proc/<pid>/io file.
Here you will find 4 key values:

rchar: the total number of read bytes from the application point of view (ie: with no difference made between read satisfied from the physical storage rather than from the cache)
wchar: as above, but about written bytes
read_bytes: the bytes really read from the storage subsystem
write_bytes: the bytes really written to the storage subsystem

Say a process has the following values:
rchar: 1000000
read_bytes: 200000

The read cache miss ratio (in bytes) is 100*200000/1000000 = 20%, and the hit ratio is 100-20 = 80%
There is a catch, however: the rchar value includes thing as tty IO, so for processes that read/write a lot from/to a pipe the calculation above will be skewed, reporting higher hit ratio than the effective one.


Have Total update automatically when different shipping option chosen in Expresso Store

Question: Is there a way, on the Checkout page, to have the Total automatically update when the buyer chooses a different shipping option (without clicking Update Totals)?
Comment: I did something like that, but the strange thing is that the country is only updated once when i shop as guest, next ajax calls work like they should but the shipping costs aren't calculated anymore. But with the same script as a logged in member it's possible to recalculate on every ajax call? Is there any hidden option to prevent this for guests? Thanks Peter
Comment: To play by the rules of StackExchange you'll need to post this as a new question rather than an answer to an existing question. But by all means link to this thread or any others which are relevant as they help to provide a little extra info.
Answer: Since the shipping option and subsequently the total are not updated until the cart is updated you would need to write some javascript that submitted the cart via AJAX and then updated the total accordingly.


How to Uninstall Solana from a system?

Question: I want to re-install Solana from scratch but there is no command in the solana-cli that helps to uninstall it. So what are the proper steps to completely uninstall solana from a mac system.
Answer: You can just remove the solana installation folder. You can find it running:
which solana

the output will be something like:
/Users/xyz/.local/share/solana/install/active_release/bin/solana

In that case you can remove the folder /Users/xyz/.local/share/solana
Remember to update also your environment PATH variable, you can check the content with:
 echo $PATH

it probably contains the solana folder you just removed.
Answer: remove from PATH
and delete the folder of your installation - in the installation below /home/solana/**
downloading v1.14.6 installer
Configuration: /home/solana/.config/solana/install/config.yml
Active release directory: /home/solana/.local/share/solana/install/active_release
* Release version: v1.14.6
* Release URL: https://github.com/solana-labs/solana/releases/download/v1.14.6/solana-release-x86_64-unknown-linux-gnu.tar.bz2
Update successful

Comment: why have you added solana installation log
Comment: To help you give an example of where your installation might be.

I also provided you the exact steps to remove your installation.

Not sure why you downvoted?
Answer: I didn't find an "uninstall" capability.  From config.yml in .config//install
releases_dir: /home/sol/.local/share/solana/install/releases
active_release_dir: /home/sol/.local/share/solana/install/active_release
Don't install this as root but if you do and you want to set up as a new user with existing config objects that were owned by root you will have to fix some permissions and group ownership and copy/delete some files.

How to Uninstall Solana from a system?


How do I delete activities?

Question: How do I delete an activity that I have created and assigned to myself?
I cannot see a button that says delete, only an edit button?
Answer: There should be a link on the "Activities" tab marked "Delete" for each activity listed.  See screenshot:

If you do NOT see this button, it's most likely that you don't have the "Delete Activities" permission.  Please speak to whomever manages permissions for your CiviCRM installation.

How do I delete activities?


Transfer large amount of money from one Wells Fargo account to another

Question: I'm helping my fiance pay off her student loans. We both have Wells Fargo accounts. What is the quickest and cheapest way to transfer a large amount, say $20K or more, to her account? I'd prefer to stay away from fees and any tax issues. I know Wells Fargo online allows you to transfer up to $1,500 a day and limits you to $20K a month, but is there a faster way to transfer a large amount safely? I'd prefer not to have these loans accruing more interest.
Comment: If she's your *wife* and not *fiance*, then there's no gift tax issues on transfers between you two, by the way.
Comment: What's wrong with checks?
Comment: BTW: $20K will require paying gift tax
Comment: the threshold for gift tax is $13500 a year. You can use the lifetime exclusion, as mentioned, but it comes on the account of the estate tax/later gifts.
Comment: If I were to transfer $1,500 a day online till I hit the $20K monthly limit, would I still be required to pay gift tax?
Comment: $14K gift tax exclusion in 2013. ($11,000 in 2002-2005, $12,000 in 2006-2008, $13,000 in 2009-2012 and $14,000 on or after January 1, 2013) Never $13.5K.
Answer: The key is to avoid the gift tax, or gift tax paperwork.
If you are getting married THIS year and you want to get this done quickly:

Write a check to the loan servicing company for $14,000.
Get married
Write a check for the rest of the $20,000 to the loan servicing company.

If you are getting married NEXT year and you want to get this done quickly:

Write a check to the loan servicing company for $14,000.
Wait until the first business day of next year.
Write a check for the rest of the $20,000 to the loan servicing company.

Note: $14,000 is the current threshold for gift tax rules for an exchange from one person to another. There is no limit from one spouse to another, if both are US citizens.
Comment: If I were to send a check or transfer money for all $20,000 how much gift tax would I need to pay next year? Or better, how do I figure how much gift tax I would need to pay in my taxes?


Supprimer vs fermer vs clôturer

Question: When a user requests to close his online account which will result in all the user's data being removed/deleted (account can no longer be re-activated after), what's the best French verb that resembles this? Supprimer, fermer or clôturer?
Answer: As a French, I think that "supprimer" is the best word for this situation because the account is completely removed, with its user data.
The word "fermer" can be used too, but I think it can be confusing if you say "Je ferme mon compte" because sometimes you could understand that you close your account without being sure that the data is removed. Notice that if your account is closed by the administrator of the website, you would more likely use "Mon compte a été fermé" because you haven't decided to close your account.
The word "clôturer" is, like @Alone-zee mentionned, when you close a bank account.
Example:

J'ai supprimé mon compte.

In this situation, I am sure that my account has been deleted.

Mon compte a été fermé par les administrateurs du site.

In this situation, my account has been closed by the websites administrators.

J'ai fermé mon compte.

It can also be used in the case that the user closed his account, but it is not used very often.

J'ai clôturé mon compte.

It is used when you close a bank account.
If you want to close you account temporarily, or if it has been shutdown temporarily by the administrators, you would use the word désactivé

Mon compte a été désactivé par les administrateurs
Answer: When an online account is closed for good, "fermé" is the most appropriate word; "supprimé" (albeit not entirely wrong) is usually more about a video being removed, deleted. "Clôturer" is used more formally (as an antonym of "ouvrir") when you close, for instance, a bank account.
A YouTuber explaining the reason for the closure of his account:
« Pourquoi cette chaîne est-elle fermée ? »

"Fermé" conveys the idea of an account being closed permanently:

Le compte Twitter de Donald Trump a été fermé.

With "supprimé / coupé / désactivé", on the other hand, an account may be closed only temporarily (accidentally or otherwise), with "désactivé" especially emphasising this temporary nature:

{vs}: Le compte Twitter de Donald Trump a été supprimé / coupé / désactivé.
Comment: *Supprimé* would be even more drastic than *fermé*. It would mean that the content isn't accessible anymore and possibly that all the data has been erased. Also I wouldn't use *coupé* for an account.
Comment: *Suspendu* too for a temporary state.

Supprimer vs fermer vs clôturer


How does increasing the number of transistors in a chip increase its speed?

Question: Is the only purpose of transistors in a CPU to act as the switches that define its instruction set?  And if so then why does increasing the number of transistors increase its speed?
Comment: This question is answered in more detail at this Electrical Engineering Stack Exchange question: http://electronics.stackexchange.com/questions/5592/why-does-more-transistors-more-processing-power (It is not clear if that kind of detail is appropriate here.)
Answer: Off the top of my head:

More cache, which is faster than RAM
More SIMD instructions, which process faster than single-data instructions
More cores, so you can do two or more things at once
More functional units, like built-in FPUs, and multiple ALUs
Pipelines, so each core can do more things at once
Better processing logic, like more sophisticated branch prediction logic
Comment: http://www.camelback-comparch.com/Technical-Highlights/Technical-highlights.html
Answer: If you're curious about this sort of thing I highly recommend the book The Elements of Computing by Noam Nisan and Shimon Schocken (at least the first half).  After going through it you'd be able to answer your own question in great detail with a full appreciation of the parts involved.
The companion website actually has some sample chapters and notes.  It's a very approachable book.  I went through it on my own with no problem and then took a brand new class at my university that used it as its primary text.
Answer: The simple answer is that more transistors doesn't make the rest of them go faster, but instead of doing one thing per time period, we can now do two (with some limitations).
Answer: Ken already summarized some of the reasons in his answer. To expand on that further

More cache, which is faster than RAM

Obviously bigger caches need more transistors. But with more transistors we also have the choice of using faster caches. CPU caches are just SRAM which is typically made from 6 transistors (A.K.A 6T SRAM). However when there are enough transistors it may be worth using faster but bigger SRAM cells made from more than 6 transistors (such as 8T, 10T SRAM)

More SIMD instructions, which process faster than single-data instructions

Not only SIMD but any type of accelerating instructions. For example modern architectures often have an AES unit for faster encryption/decryption, FMA for better mathematic computation (especially digital signal processing), or virtualization for faster virtual machines. Supporting more instructions means more resources are required to decode and execute them

More cores, so you can do two or more things at once
Pipelines, so each core can do more things at once

These are quite clear

More functional units, like built-in FPUs, and multiple ALUs

In the past there was not enough die area for the FPU so people must buy a separate one if they have high requirements of floating-point arithmetic. With significantly more transistors it's possible to have the FPU built-in, speeding up floating-point math a lot
Besides, modern CPUs are superscalar and will try to do multiple things at once by finding independent data pieces and calculate them earlier, even though the instruction stream is linear and serial. The more things they can do in parallel the faster they'll be. To do that a CPU can have multiple ALUs and an ALU can have multiple execution units. If for example a CPU has 5 adders compared to 4 in the previous generation then it's already running 25% faster in the most optimistic situation without any clock changes. More sophisticated CPUs even employ out-of-order execution (which is the case for most modern high-performance CPUs)

Better processing logic, like more sophisticated branch prediction logic

Operations can typically be done in various ways. If you have more transistors you'll have more resources to use a faster technique. Some simple examples:

Bit shifting:

A simple shifter is made by serially connecting flip-flops together.

That needs just one flip-flop per bit, hence extremely compact. But it needs one clock to shift left or right one bit. That's why microcontrollers and small embedded CPUs have only instructions to shift by one. See

Is a logical right shift by a power of 2 faster in AVR?
Which is faster:  x<<1  or  x<<10?

When you have more transistors to spend you can change to a barrel shifter. Now a CPU can shift bits in a single clock with the cost of hundreds or thousands of transistors

Addition:

A simple adder is also made by connecting full adders in series. This way an N-bit adder needs N clocks to finish its job, which is certainly not what people expect in a CPU

With more transistors we can speed up the addition by pre-calculating the carries with carry-lookahead or carry-save adder. The full adders are still used, but a lot more space is needed for the the carry-precalculation unit

The same thing applies to other units like multipliers, dividers, scheduler... For example we can do a multiplication extremely fast in a single clock using combinational logic. You can see some simple examples in the question 3-bit multipliers - how do they work?. But the transistors needed will grow to the square of the input widths, therefore small CPUs with a multiplier use sequential logic instead to save a lot of space for the multiplier:

Older multiplier architectures employed a shifter and accumulator to sum each partial product, often one partial product per cycle, trading off speed for die area. Modern multiplier architectures use the (Modified) Baugh–Wooley algorithm, Wallace trees, or Dadda multipliers to add the partial products together in a single cycle. The performance of the Wallace tree implementation is sometimes improved by modified Booth encoding one of the two multiplicands, which reduces the number of partial products that must be summed
https://en.wikipedia.org/wiki/Binary_multiplier#Implementations

Once you have a huge pool of transistors you can even use combinational logic to do an FMA which is far more resource-intensive than a multiplier

Modern computers may contain a dedicated MAC, consisting of a multiplier implemented in combinational logic followed by an adder and an accumulator register that stores the result. The output of the register is fed back to one input of the adder, so that on each clock cycle, the output of the multiplier is added to the register. Combinational multipliers require a large amount of logic, but can compute a product much more quickly than the method of shifting and adding typical of earlier computers.
Multiply–accumulate operation
Answer: Increasing the number of transistors is usually done by making them smaller, which makes them closer together, which reduces signal propagation time.


Can't execute boot2docker command on TeamCity command line build step

Question: I am trying to add docker commands on TeamCity build steps using the normal command line option. I have Windows environment so I have to use boot2docker.
I can execute the command like:
"C:\Program Files\Boot2Docker for Windows\boot2docker.exe" ssh docker images on Windows command line. It will return a list of my docker images.
However, I'm not able to run the same command on TeamCity using the Command Line runner type. I always get the error message error in run: VM "boot2docker-vm" is not running.

Anyone get ideas? Thanks.
Answer: The error message is clear: boot2docker-vm is not running
Login on your server and run boot2docker up on its command line. That will start the boot2docker VM. Then try again.


Crop all written letters from single image

Question:

Above image has handwritten hindi / deavanagari letters all on a single

image.
Task is to Prepare a dataset from the given assignment.jpg image using image

processing tools
Idon't have clarity whether i can use photoshop editing tools like adobe photoshop etc.
If image processing tools mean opencv , is it really possible to create like a emnist like dataset from single image.
I am not able to come up with any way to seperate the letters from eachother
Comment: You have non overlapping crystal clear bitmaps, there is no difficulty in extracting the bounding box of each letter. What do the letters (foreground) have, that the background (paper) does not? What do the pixels that belong to the same letter have in relation to the pixels that belong to a different letter?
Comment: These characters are almost segmented already :) So how about defining a fixed grid on top of the image and cropping out each cell? If the characters in a next image (presumably you would have multiple such sheets) don't move a lot, then you can always segment them with this simple way.
Comment: @A_A , i think foreground letters have color black and background is white.I don't know how to find relation to pixels that belong to different letter.Even if it is possible i think it involves image processing, I don't know any concepts in image processing.
Answer: Presumably this is an academic assignment of some sort and you are expected to use a specific tool, OpenCV I am guessing. You should review the documentation for that tool and try to find a feature which matches the requirements. I suspect you would need to use the Image Segmentation feature: https://docs.opencv.org/3.4.3/d3/db4/tutorial_py_watershed.html


How do I identify resonating structures for an Organic compound

Question: Basically, my concepts regarding Resonance are not totally clear. I just need some help, on how to find the no. of resonating structures, given a molecule, and how do I draw those structures. Some examples would be pretty helpful. Thanks
Answer: Essentially, resonance structures are explained by Resonance Theory. Resonance theory looks to answer the question: How do we reconcile the differences between Lewis Structures of species and their observed characteristics? There are a few rules that must be followed when determining resonance of compound.

Resonance occurs in species for which there are two or more valid Lewis structures.

For a species, each valid Lewis structure is called a Resonance Structure or Resonance Contributor. In these cases, you are simply moving an electron or pair of electrons to another location in a molecule. An example is HCO2-.There are two possible resonance contributors in this molecule. As shown in the example, resonance structures differ only in the placement of their valence electrons, not their atoms.

Resonance structures are imaginary; the one, true species is represented by the resonance hybrid.

The Resonance Hyrbid is the weighted average of all resonance structures. An example of the resonance hybrid occurs in either of these molecules.

The resonance hybrid looks most like the lowest energy (most stable) resonance structure. Essentially, the least formal charges on the molecule, or most evenly distributed charges.

A few tips I have for drawing resonance structures based on Lewis structures for different molecules include:

Move away from a negative charge. If presented with a negative charge on a specific atom, it means that there is an excess of electrons on that atom. Either take electrons away from the atom, or move a bond that it is involved in.
Move towards a positive charge. A positive charge represents a lack of electrons, this means that you should move electrons to the atom with the charge, or move a double/triple bond to allow it to become involved in another bond.
Move away from a radical. A radical does not represent a charge, as it is only a single electron, but you should (in most cases) move electrons away from the radical.

Also, always remember that electrons are the only things that move in resonance structures. They can also not be added or subtracted, but only moved. Make sure not to move/add/remove any atoms, and you cannot move electrons to an atom that is already saturated with bonds for example, an sp3 hybridized Carbon as it is already saturated with Hydrogens.
Best of luck!
Comment: Wow. Thanks. That should hopefully clear some facts for me
Comment: 1. There are more than two resonance contributors in $\ce{HCO2-}$. 2. **There is no most stable resonance structure!** 3. "Essentially, the least formal charges on the molecule, or most evenly distributed charges." This might be purely based on experience and is not at all true. The prime counter example is CO.
Comment: Yeah for sure, let me know if there are any other questions that I can help with! :D


Does $\sin (5x)=5\sin(x)$? Why or why not?

Question: This may sound like a dumb question, but does $\sin(5x)=5\sin(x)$? Can you say this for any trigonometric function if it is true (e.g. can $\tan^{-1}(7x)=7\tan^{-1}(x)$). Again, I am pretty sure I am wrong, but I am just wondering for my future work on trigonometry. If they are not equal, then please tell me what the difference is between the two. Thanks!

Note: I have not had much practice with trigonometry, so please do not answer with some kind of complicated Taylor Series thing (I have heard about it, but don't fully understand it). Thanks again
Comment: They are not equal. A most obvious reason is that $\sin(5x)$ never exceeds $1$ (being equal to the $y$-coordinate of a point on the unit circle). But $5\sin x$ can be as large as $5$ (being equal to the $y$-coordinate of a point on the unit circle multiplied by five).
Comment: The $\sin$ function is NOT linear.
Comment: Check [this](http://tinyurl.com/kep3y85) out, it could be helpful! :)
Comment: There should be a few values $x$ for which you are familiar with the value $\sin (x)$. (If there aren't, you should learn a few! Having a few examples/computations to keep in mind when thinking about mathematics is vital. I cannot stress this enough.) Does your conjecture hold for these values?
Comment: I should have thought of this before I asked the question.... $\sin(3\times 30)=1$, but $3\sin(30)=3\times 0.5=1.5$!
Answer: No, placing a constant factor inside of the sine function, as in sin(a*x) changes the frequency of the function; if |a| is greater than one, it "squishes" the sine function horizontally, making it oscillate "faster", and if |a| is less than one, it "stretches out" the function horizontally, making it oscillate "slower". Placing the factor in front of the function, as in a*sin(x), scales the amplitude of the function, "stretching", or "squishing" it vertically.
The best way to observe it is to look at a graph and to see what it does: http://www.wolframalpha.com/input/?i=plot+sin+x%2C+sin+3x%2C+3*sin+x
I suggest playing around with other values in the graphs to see what they do.
Answer: 1) You could have just plotted the functions in, e.g., wolfram alpha and see for yourself.
2) for $t=\frac{\pi}{2}$ one has $\sin (t)=1$ and since $|\sin (x)|\le 1$, it is clear that $\sin (5\cdot t)\ne 5\cdot \sin(t)$.
Answer: I'll try to explain the difference between the two with a picture: (Apologies ahead; it's a rough sketch done in Microsoft Paint.)

Here, we have a circle (suppose with radius 1) with its center at (0,0), with a line (call it $l$) drawn from the center to the edge of the circle (ending at $P$). $A$ is the angle the line makes with the $x$ axis.
To get $5\sin(A)$, we blow up the line and the circle to 5 times its original size. $l$ is now 5 times the length, but still has one point at the center of the circle, and makes the same angle with the $x$ axis. The $y$-coordinate of the other end of $l$ is $5\sin(A)$.
To get $\sin(5A)$, this time we don't blow the circle and the line bigger. Instead, we're rotating the line around the center of the circle so that the angle it makes with the $x$-axis is 5 times bigger. Now, the $y$-coordinate of the point where $l$ meets the edge of the circle is $\sin(5A)$.
Try it out with an example or two; you'll see the difference yourself.
Comment: I think your answer does the best job at helping the OP: thank you for the effort.
Comment: @EricStucky Yeah, I figured OP was looking for an explanation in simpler terms. So I provided one.
Answer: Something like $a\cdot f(x)= f(a\cdot x)$ is true if and only if $f(x)$ is linear. Since there are always nonlinear terms in the Taylor expansion of a trigonometric function this can't be true for any.
Comment: Isn't $f(x)=x+1$ linear?  But $5f(x)=5x+5$ and $f(5x)=5x+1$.
Comment: Functions satisfying the stated property are called homogenous, not linear. Any linear function is homogenous, but not necessarily vice versa. As for $x\mapsto x+1$, it is not a linear function. Rather it is an example of an affice mapping.
Comment: the argument that since the taylor expansion contains nonlinear terms, then the function itself is not linear is true, but requires some proof (easy). But, for the question posed resorting to the Taylor expansion of the function is really an overkill. Simply plugging in some values into the purported equation immediately shows it does not hold.
Comment: I was assuming that the OP (not the answerer) was more familiar with calculus rather than with linear algebra.  See [Wikipedia](http://en.wikipedia.org/wiki/Linear_function), where a linear function is sometimes defined as a polynomial function of degree zero or one.
Answer: Assume that the identity $\sin(5x) = 5\sin(x)$ is true. Since we know that $\sin(180^\circ) = 0$, we'll have: $0 = \sin(180^\circ) = \sin(5*36^\circ) = 5*\sin(36^\circ)$, hence $5*\sin(36^\circ) = 0$, which mounts to $\sin(36^\circ) = 0$. Is this true?
Comment: Using degrees rather than radians should be discouraged.
Answer: The trigonometric functions are functions and as such are usually represented using function notation.  Recall that the function notation $f(x)$ means that function $f$ is accepting $x$ as its input.  It does not mean that $f$ and $x$ are being multiplied.  So the notation $\sin(5x)$ means that the sine function is accepting $5x$ as its input.  The notation $5\sin(x)$ means that 5 is being multiplied to the output of the sine function when its input is $x$.  Is everything clear now?
Comment: Just to clarify that there exist functions with the property that $f(c\cdot x)=c\cdot f(x)$. Such functions are called homogenous.
Answer: Both of the equalities that you wrote above are NOT true. One way to look at this might be to use their Taylor series expansion. $\sin (5x)$ means the sine of $5$ times an angle measure $x$. This means in a right triangle whose hypotenuse is of length $1$, the perpendicular corresponding to the acute angle $5x$ has length $\sin (5x)$.
While for $5 \sin x$, one should consider a right-triangle with hypotenuse of length one and the perpendicular corresponding to an acute angle $x$ and then take $5$ times the length of this perpendicular.
You can draw some such right triangles to verify the results yourself.
Comment: Using Taylor series here is a major overkill. Simply plug in some values and observe.
Comment: @IttayWeiss haha. I can only agree :-)


For what condition boosting work better than bagging in Ensemble Learner?

Question: In boosting process we get a better accuracy for training data, but there is a lot of chance to over fit. For bagging ensemble method over fitting chance is lower than boosting.
Why we use boosting and for what condition ??
Answer: Bagging (and features sampling) aim to reduce variance by providing low-correlated trees. Estimators can then be aggregated together to reduce variance. Reason is simple decision trees tend to quickly overfit in the bottom nodes. Bagging and features sampling only adress high-variance (overfitting) problems.
On the other hand, boosting is a meta-algorithm that aims to reduce both bias and variance by training estimators in a sequential way. Each predictor tries to reduce residuals from previous estimators.
In my opinion, the two meta-algorithms can't be easily compared that way. They will give you different results depending of data distributions, potential outliers, usecase... Potentially, boosting is more sensitive to outliers than bagging for example. I think trying the 2 methods is your best chance and you don't have to restrict to only one model.


Can I place a row of letters that makes multiple new words in combination with tiles already on the board?

Question: player A makes LACE as a horizontal line play.
player B adds Y to make LACEY then puts E A vertically to make YEA down in the same play
I claimed that was not legal as it is two  turns in one. The other 3 players all disagreed and allowed the play
Comment: The answer below covers why this is a legal play.  As a suggestion be on the look out for pluralising words.  Sticking an 'S' on the end of a word whilst creating a new one going other direction is a good thing to look out for.
Answer: From the official rules on the Hasbro website:

3: [...] All letters played on a turn must be placed in one row across or down the board, to form at least one complete word. If, at the same time, they touch others letters in adjacent rows, those must also form complete words, crossword fashion, with all such letters. The player gets full credit for all words formed or modified on his or her turn.
4: New words may be formed by:

Adding one or more letters to a word or letters already on the board.

Placing a word at right angles to a word already on the board. The new word must use one of the letters already on the board or must add a letter to it. (See Turns 2, 3 and 4 below.)

Placing a complete word parallel to a word already played so that adjacent letters also form complete words. (See Turn 5 in the Scoring Examples section below.)

So player B was following the rules by playing the word YEA in a single row, and at the same time it adds the Y to the LACE already on the board, as per the second dot point above.
Player B will score points for both LACEY and YEA in this case.
Comment: Note than when scoring points for LACEY, any modifiers under the L, A, C, or E are not applied, as they are only applied once.
Comment: Or more accurately, the bonuses only apply the turn you put the tile on top of them. If you played the Y on a double-letter, for example, it would be worth double points in both LACEY and YEA.
Comment: My understanding is that YEA is being played in a column.


MySQL my.cnf: innodb_log_file_size is missing

Question: How to set innodb_log_file_size to MySQL database if there is no innodb_log_file_size in my.cnf configuration file? I'd like to backup via Percona Xtrabackup and the backup crashes at this point telling me that my innodb_log_file_size is different than it expects.
Answer: Login to mysql and run this
SHOW GLOBAL VARIABLES LIKE 'innodb_log_file_size';

or this
SELECT variable_value FROM information_schema.global_variables
WHERE variable_name = 'innodb_log_file_size';

This will give you the size mysqld has. The default for MySQL 5.5 is 5M.
Whatever number that turns up should be placed in my.cnf. If it is not set, then place this
[mysqld]
innodb_log_file_size = (Whatever the filesize of ib_logfile0 is)

Try out xtrabackup after adding this to my.cnf.


Interpretation of Ricci rotation coefficients in tetrad formalism

Question: Given an orthonormal frame (tetrad in 4 dimensions, vielbein more generally) $\{(e_{\mu})^{a}\}$ with $g(e_{\mu}, e_{\nu}) = \eta_{\mu\nu}$, the Ricci rotation coefficients are defined as $$\omega_{\lambda\mu\nu} = (e_{\lambda})^{a}(e_{\mu})^{b}\nabla_{a}(e_{\nu})_{b}$$ and you can extract information about the curvature of the spacetime in question if you have all the relevant Ricci rotation coefficients. My question is: what is, exactly, the geometrical/physical interpretation of the Ricci rotation coefficients? In a vague sense, I can see that they account for "non-inertial" effects that a local Lorentz observer would detect if them chose this respective vielbein as their frame, which in turn would give information about the local curvature, but that is very hand-wavy; I wanted something more illuminating. So is there any intuitive sense I can give to these coefficients?
Comment: What is your interpretation of the Christoffel symbols?
Comment: @MBN Somewhat in analogy to what happens in a noninertial frame of reference in newtonian mechanics, and so summarize it in a few words, the Christoffel symbols would carry the information on how the coordinate basis is varying thoughout spacetime, or how the coordinate basis fails to be parallel transported in the directions of its respective basis vectors. So that would be precisely the same as the Ricci rotation coefficients, right (now that you've made me explain that to myself, it already seems a bit more clear)?
Answer: I think what you said in the comments is right. I don't know if what follows give you more intuition. In your notation, $\big\{e_{\nu} \, : \, \nu = 1...n \big\}$ is a frame of $n$ linearly independent vector fields $$e_{\nu}(x) = \big(\,e_{\nu}(x)\,\big)^b \,\frac{\partial}{\partial x^b}$$ that determine the frame. The part
$$(e_{\lambda})^a \nabla_a \, (e_{\nu})_b$$ should more accurately be written as
$$\Big((e_{\lambda})^a \nabla_a \, e_{\nu} \Big)_b$$
and so
$$\Big((e_{\lambda})^a \nabla_a \, e_{\nu} \Big)^b \frac{\partial}{\partial x^b}= \nabla_{e_{\lambda}} \, e_{\nu}$$
is the covariant derivative of the frame vector field $e_{\nu}$ in the direction of the frame vector $e_{\lambda}$. The derivative  $\nabla_{e_{\lambda}} \, e_{\nu}$ is a vector that describes how the frame vector $e_{\nu}$ deviates from its parallel transport when moved slightly in the direction of the frame vector $e_{\lambda}$. In other words, it measures the "rotation" of vector $e_{\nu}$ when moved along vector $e_{\lambda}$. Then you take the "projections" of these deviation vectors $\nabla_{e_{\lambda}} \, e_{\nu}$ onto the axes of the frame
$$\Big(e_{\mu}\circ \big(\,\nabla_{e_{\lambda}} \, e_{\nu}\,\big)\Big) =
(e_{\mu})^b \, g_{bs} \, \Big((e_{\lambda})^a \nabla_a \, e_{\nu} \Big)^s = (e_{\mu})^b \Big((e_{\lambda})^a \nabla_a \, e_{\nu} \Big)_b = \omega_{\lambda \mu \nu}$$ where $g_{bs}$ is the Riemannian (or Lorentz) metric.
So the Ricci rotation coefficients are (related to) the coordinates of the derivative vectors that measure the deviation (rotation) of all the frame vectors when moved in various directions. Observe that the Ricci coefficients carry information about how the frame twists and rotates (so how non-inertial it is) and not just information about the curvature of space-time. Even in a flat space-time the coordinates may be non-linear, and hence non-inertial, so the Ricci rotation coefficients may still be non-zero. The point is that in flat space-time there is a system of coordinates in which they can all be made zero. In curved space-time that's not the case.
Remark: Christoffel symbols encode how the differentiation of an object on a curved space (a space with non-trivial geometry) in the direction of a tangent vector differs from the usual differentiation of the object in the direction of the vector in flat space (trivial geometry).


GRUB Issues Acer Aspire v5-513

Question: OK, this laptop is pissing me off.
I did a dual-boot install of Windows 7 alongside Ubuntu 13.04.  I've done this many times on other systems, and never had a problem.  I am now.
The installation went fine, no errors at all, and I rebooted the laptop, ready to enjoy my new installation.  It didn't happen.  It didn't even bring up GRUB, just went right into Windows.  I rebooted into the live DVD and ran grub-install and update-grub, which both succeded with no warnings.  I rebooted...still no GRUB, so I updated the BIOS and tried again.  Still nothing.  I'm stumped and have no idea what to do.
The BIOS isn't a SecureBoot BIOS, and I honestly have no further idea what it could be.
Answer: You have to hit F12 over and over again until it takes you to a "special" boot menu. There, it will allow you to select what partition\drive to boot into. I have the same problem. The issue is that new machines skip over all boot selectors for some reason and just go straight to Windows to speed things up.
Answer: You could try installing EasyBCD (http://neosmart.net/EasyBCD/) on windows 7. Once in that, go to "add new entry" and select the "linux/bsd" tab and select type as "grub2" and click on "add entry". Save the settings and reboot. You should see grub option in the windows 7 bootloader now.
Answer: You cannot just re-install grub from live installer unless you mount partition with install first. And you can only run the update from inside you install either after you have booted or from a chroot into your install.
How to restore the Ubuntu/XP/Vista/7 bootloader
https://help.ubuntu.com/community/RestoreUbuntu/XP/Vista/7Bootloader
https://help.ubuntu.com/community/Grub2/Installing#Fixing_a_Broken_System
Often easier just to use Boot-Repair.
Boot Repair -Also handles LVM, GPT, separate /boot and UEFI dual boot.:
https://help.ubuntu.com/community/Boot-Repair
You can repair many boot issues with this or 'Create BootInfo' report (Other Options) & post the link it creates, so we can see your exact configuration and diagnose advanced problems.
LighterWeight (Lubuntu based) Boot-RepairCD
http://sourceforge.net/projects/boot-repair-cd/files/

GRUB Issues Acer Aspire v5-513


independent variables in Random forest model

Question: Is it reasonable to run a random forest model with an independent variables that has almost little or no variations. How they impact the model and whats their role in predicting the dependent?from technical point of view I believe they will not be used in building the tress and will have no role in predicting the DV
Answer: There's a big difference between "little" and "no" variation.

If a variable has little variation, it can still have predictive importance. This should be obvious: if all values of a feature larger than some constant $c$ corresponds to one  class, and all other values to the opposite class, it's a really good predictor. (Likewise, if it's completely independent of the class label, then it's worthless.) This is true no matter what the variance of the feature.
A variable with no variation cannot predict the outcome. It won't be selected as a feature, since splitting on the feature can never provide information gain. Including (a large number of) zero-variation features can harm the model, however, because random forest randomly selects feature subsets at each split; a large number of invariant features means that the model will not have any information to split on if the random features are all worthless.
Comment: It's worth mentioning that "little" variation is relative to the units in which the variable is measured.
Comment: Just that the OP didn't mention their concern was indicator variables, and I've seen the "small variance" belief be an issue with new data scientists.


Would anyone use "ramp down" as the opposite to "ramp up"

Question: In the context, for example, of factory production I often read the phrase "ramp up production" or "a ramp-up in production". To me "ramp down" sounds a strange phrase to use as the opposite - does anyone have a more apt antonym?
Comment: It makes perfect sense if you are in the habit of graphing some metric as a function of time. The growing phrase is a "ramp up" and the declining phase a "ramp down".
Comment: I personally use it, although I can't remember the last time. I often will say "wind down" (wind as in winding a string, not the wind makes it feel cold today)
Comment: Thanks for all the answers/comments/suggestions. I suppose a lot of the suggestions indicate a permanent change (wind down, down size, down scale, phase out) rather than a strategic short-term or seasonal reduction. It seems that ramp down is primarily used in technical contexts.
Comment: If any of the answers does answer your question satisfactorily, please do click on the tick (check) mark next to that answer, to indicate that you've accepted it. Both you and the answerer will receive reputation points for this.
Comment: I've heard "ramp down" plenty of times to describe the end of a software project, in the same way "ramp up" is used at the start. I think it's fine.
Answer: The antonym for "ramp up" will depend on context.
You might use: reduce, decrease, down size, down scale, or wind down (e.g. we talk of our department winding down for Christmas - a temporary gentle slow down in office presence and productivity).
Ramp down is used in some technical settings. For example, when the grid controllers instruct a power plant to reduce its output, that's referred to as "ramping down":

On receipt of a cease instruction from National Grid the unit will begin to ramp down (i.e start to cease provision of the service and return to its pre-instructed MW)

(from a National Grid document on grid balancing)
The oldest reference I can quickly find for a metaphorical use of "ramp down" is from 1970, and again it's a technical electric/electronic reference:

When the switch changes over, the integrator output commences to ramp down towards zero volts

source: Instrument practice for process control and automation, Volume 24. United Trade Press, 1970
Comment: In particle physics we "ramp up" and "ramp down" the current in big magnets.
Answer: TO the extent that it has an opposite, I think the opposite of "ramp up" is "wind down". These sorts of idioms are not always consistent or literally meaningful.
Answer: I've seen this word used in Breaking Bad when Walter described that their chemical work is not going to stop:

We're not ramping down. We're just getting started.

Video clip: https://www.youtube.com/watch?v=OyabiLNfjQw
Answer: I'm not sure about the credibility of the source, but according to this website:

The verb "to ramp" entered English in the 14th century, and the
  expression "ramp up" was first applied to climbing plants such as
  vines. From this usage, "to ramp up" came to mean a general escalation
  or a rapid increase in activity.

In this case, it sounds like "ramp up" refers to a indication of growth, not a synonym of it.
If you're looking to communicate the opposite of growth, Atrophy is a good word.
Answer: How about scale back or phase out?


How can I append custom data to images in the editor?

Question: I've added a custom meta field to my image details so that a client can add a number to their photos (a design choice). The data would need to show up under each image (like a caption) inserted into the editor when the user inserts into post (I can't use the caption for my purposes because WordPress won't let me nest shortcodes, and I'm using a grid columns plugin which relies on shortcodes).
Found out that you can indeed nest shortcodes—the editor just wasn't inserting the image with caption in the right spot and someone had told me you couldn't nest them. What they meant was that you can't nest the same shortcode: http://codex.wordpress.org/Shortcode_API#Nested_Shortcodes
I'd still like to know if I can add a field that could be specifically for this purpose rather than the caption. Here's what I used to add the custom meta field:
/**
 * Add image number metabox to the media details
 */

function ra_attachment_fields_to_edit($form_fields, $post) {
    $form_fields["image_number"] = array(
        "label" => __("Image Number"),
        "input" => "text", // this is default if "input" is omitted
        "value" => get_post_meta($post->ID, "_image_number", true),
    );
   return $form_fields;
}
add_filter("attachment_fields_to_edit", "ra_attachment_fields_to_edit", null, 2);

/*
 * Save it
 */
function ra_attachment_fields_to_save($post, $attachment) {
    if( isset($attachment['image_number']) ){
        // update_post_meta(postID, meta_key, meta_value);
        update_post_meta($post['ID'], '_image_number', $attachment['image_number']);
    }
    return $post;
}
add_filter("attachment_fields_to_save", "ra_attachment_fields_to_save", null , 2);

Answer: Use get_post_meta(); in your template to get that metadata attached to that image.

<?php echo get_post_meta($post->ID, '_image_number', true) ?>


Unpaired electrons

Question: Am I right in saying this: If there is an unpaired electron, then there is no neutral charge in that atom and a negative charge is given since the electron doesn't cancel out, since there is no pair. So does that negative atom carry that unpaired negative charge? And does that atom/element, like cobalt attract things because of the negative unpaired electron and how it attracts a proton from a different atom? Someone please make it clear to me.
Comment: Pairs of electrons do not cancel out each others charge. They are both negative charged. The electron charge in atoms is compensated with the protons of the atom. So your statement is completely false.
Comment: Pairing is about spin not charge.
Comment: Welcome to chemistry.stackexchange.com. Feel free to take a [tour] of the site. Visit the [help] for any unanswered questions remaining. Your first statement is incorrect, btw. A lot of atoms and even stable molecules have unpaired electrons: $\ce{O2, NO, NO2, \dots}$
Answer: Your statement is unfortunately wrong, as the electrons all carry a negative charge (that you could say is balanced by the positive charge of the protons in the atom nucleus). Single atoms of an element are neutral but can have unpaired electrons.
Atoms with paired charges can be negatively charged, most common ions like Cl- have no unpaired electrons and the addition of the electron that formed the final pair added the negative charge.
Electron pairing is about spin, electrons with opposite spins pair together to form a much more stable arrangement releasing energy.

Unpaired electrons


recommend firewall options for a dedicated server

Question: I'm looking for recommendations on firewalls for a dedicated server that will be hosting a few websites of average traffic (5000 uniques monthly).  the hosting company has port and full hardware firewalls.  There's also the option of installing software firewalls.  What is the level of protection of 'port' protection mentioned here: http://www.xlhost.com/firewall.php?  Is this adequate?  Any recommendations (Windows Server OS)?
Comment: Added - windows server
Answer: Well if this is Windows Server 2008, it actually has a fairly capable software firewall.
Comment: Well, I think *really good* is a stretch. I'd still much prefer pf or iptables, but in this situation, that's obviously not an option.
Comment: Yup, the built-in windows firewall is really good.
Comment: I think *any good* is a stretch. Theres many features it lacks, and in a not so distant past ksecdd was vulnerable to a use-after-free condition stemming from how the firewall processed malformed ICMP packets - Among other problems. It can't be trusted.
Answer: It looks like a port on a FireBox would offer decent protection. Do you want application level protection? The FireBox probably won't be able to discern different application traffic on the same TCP/IP port. Meaning, if you had a software firewall, you could configure it just a bit more granular to only allow a certain executable to have access to port 80 (for example) whereas with a port on a firewall, you could only tweak port 80 to either allow or deny traffic without respect to what executable is initiating or responding to the traffic on your server.
As ErikA pointed out, Windows Server's built-in firewall would seem to be sufficient (as long as it was Server 2008 or above). Some alternatives that are noteworthy are:

Kerio WinRoute Firewall
Injoy Firewall
Outpost Firewall Pro

With me not knowing exactly what your desires are, you'll have to do some digging to compare the products with the internal Windows firewall and see exactly what benefits are of significance to you.
Answer: Unfortunately, Getting Firewalls right is like getting encryption right - A lot of people think they can do it right, for that matter a lot of experts think they can get it right. Getting it right is not so easy.
If the FD mailing list is any guide, The firebox is vulnerable to Syn-Fin ambiguity. Best evidenced by this snippet of code.
<code>if(tcp->syn && !(tcp->ack || tcp->rst))
     tcpsyn=1;
</code>
If it isn't immediately obvious, A piece of processing code like this allows you to pass packets through the firewall as long as you set the Finish with the Synchronize bits thus effectively defeating port-filtering.
In short, If security is a concern for you, I'd stick with the tried and true - ASA/PIX. Failing that, BlackIce firewall is very well done, as well as pf/iptables of course.
Comment: Wow, great to know. However, BlackIce is dead. =(
Comment: Agreed. A Cisco ASA5505 is affordable and capable. Would be a good choice for one or more dedicated servers.
Answer: You could also look at pfsense: http://www.pfsense.org/index.php?option=com_content&task=view&id=40&Itemid=43
Answer: Assuming its actually a dedicated server and not a VPS, you could install a bare-bones linux distro on the metal (debian-netinst, etc), run Shorewall and then run the windows machine under Xen, KVM or a VirtualBox headless instance.


Emtrac Plus Battery

Question: Can someone tell me where is Emtrac Plus Silver Alloy Batteries manufactured. The brand was offered to me recently, looked very good and I bought it. Hope it performs as well as it looks.
Comment: I believe the are manufactured in India. Wouldn't trust it myself as they aren't available anywhere locally and I don't know much about them, but that doesn't mean they're bad.
Answer: The batteries are manufactured in India. The company which produces them is called Mindtrac. The reason you don't know much about them is they received seed capital in 2000 from JPMorgan as a startup. They produce tires, batteries, and some other stuff. They are supposed to be ISO 14001 certified, so apparently they worry about the environment, which is a good thing, especially for a Lead-Acid Battery manufacturer. I'm sure it would be pretty hard for them to get, considering.
Comment: ISO is only for registering, not certifying. So a company can be ISO registered, but not ISO certified. ISO varies greatly from one country to another, so ISO 14001 in India will not mean the same thing that ISO 14001 means in the U.S. Silly, since it is supposed to be a 'standards body', but this is how it actually works in practice. I know this from working for many years with a Chinese factory.
Comment: @Paul - I can only imagine! Thanks for the add :o) BTW, they label themselves as [ISO 14001 certified](http://www.mindtrac.com/gsi.html). Just going off what they've stated.
Comment: That may be what Mindtrac states on their webpage, but companies get this wrong all of the time. There is an ISO page explaining this, as well as the fact that it is a violation of the ISO IP to use the ISO trademark without the permission of the ISO (i.e., you can't put it on your products, brochures, website, etc.), but companies still violate even that all of the time.
Answer: Understand that Amaron and Emtrac plus are manufactured in same factory in India. Both same quality. Heard, quality is very good. I bought Emtrac Plus battery only 6 months ago. Lets hope all goes well. My friend used Amaron battery and it lasted over 4 years.
Comment: Now, I am not particularly concerned about which factory manufactures Emtrac Plus Batteries in India. It is a very reliable battery. I would strongly recommend Emtrac Plus. If you own a SUV, you will need a heavy duty  battery like Emtrac Plus.

Emtrac Plus Battery