Is it possible that Goku is more powerful than Beerus in Super Saiyan God Super Saiyan form?

Question: In DBZ: Battle of Gods, Goku became Super Saiyan God and he makes Beerus use upto 70% of his energy. So, is it possible for Goku to defeat Beerus in his Super Saiyan God Super Saiyan form?
Comment: There are differences @Buzka91, and here is your answer: http://anime.stackexchange.com/questions/25879/what-are-the-differences-between-super-saiyan-god-and-super-saiyan-god-super-sai
Comment: Wasn't he got trashed by Beerus even in this form?
Comment: He was trashed by Beerus in Super Saiyan God form not in Super Saiyan God Super Saiyan form
Comment: There is difference in _Super Saiyan God_ and _Super Saiyan God Super Saiyan_??
Comment: @SakuraiTomoko should also point out that during the fight Goku reverted back
Comment: @Buzka91 yes there is, Super Saiyan God is red/pink hair, Super Saiyan God Super Saiyan is Blue hair
Answer: There is no clear answer.
But according to the Wikia article on SSGSS:

The form exceedingly surpasses its predecessor, Super Saiyan God, and
  all of the other Saiyan forms.

This source also mentions that SSGSS will appear in Dragon Ball Super, so there might be a chance, but we can't be sure unless we watch Dragon Ball Super..
Comment: Actually, you can derive a conclusion from what Whiz said. The part I'm talking about, is mentioned in the Wikia article you provided :)
Comment: Yes, _but_ not for sure :p
Comment: Yeah, but its worth a mention since its been technically stated :p
Answer: As he is right now Goku is weaker than Bearus (it was said in the universe 6-7 tournament that maybe the 2 of them together could give Beerus trouble).
The 70% stuff was changed. In the anime Beerus just says he didn't use his full potential (otherwise Goku would already be several times stronger than Beerus).
So yeah, he may reach him by the end of the anime
Answer: I think Vegeta could defeat Beerus. After all, he did unlock Super Saiyan Blue evolution which cuts through the energy of destruction, something Goku hasn't been able to do yet.
Goku could take on Beerus in Super Saiyan Blue Kaio-ken times 20 since Toriyama did confirm SSJBK and SSJB evolution to be at the same level. Super Saiyan God? Maybe if Beerus was already at 100 of his power and ran out of stamina and stuff and Goku uses it at the right time and beats him somehow. Or maybe even go SSH God Kaio-ken to save stamina since Super Saiyan God Blue drains more ki than the regular Super Saiyan God form.
Answer: Well now we know the answer is no. In the tournament between universe 6 against universe 7, Hit was at the level of Goku Super Saiyan Blue Kaioken x10 (Super Saiyan God Super Saiyan Kaioken x10) . And Hit was threatened by Champa who is in a similar level than Beerus. Goku wanted to help Hit, because he knew Hit likely wouldnt be able to defeat Champa alone (and probably he wouldnt be able to defeat him at all). So if Goku super saiyan blue Kaioken multiplied 10 times might not even be at the level of Beerus-Champa, even less super saiyan blue with no multiplier. Plus in the manga they say Vegito (Goku and Vegeta fusion) seems to be in the level of Beerus. And Fusion adds the power of both fighters and multiplies it "tens of times" (according to Vados). So most likely Super Saiyan Blue is "tens of times" weaker than Beerus. Ultra Instinct Goku might be in the level or above Beerus, since Beerus didnt master Ultra Instinct (and Goku sort of did, he could use his full power/abilities but for a while)
Answer: No it is not. Since way after the Gold Frieza Saga in the manga, around book 5, Vegeta and Beerus fought, SSGSS vs Beerus base, and Vegeta lost easily. The only way Goku could beat 100% Beerus is with MUI or some crazy form like limit-breaking Super Saiyan 4.


Merging codenames with versions

Question: Should we merge all codename tags with the version tags? Already there are tags like lucid and 10.04 which are identical.
Comment: Ya. My personal opinion is to use the version numbers exclusively and fix all the 'codename' tags.
Comment: not to mention lucid-lynx and other variants
Comment: Agreed. Codenames are development versions. Releases are designated by Version numbers.
Answer: Personally, I hope that over time the Tag Synonyms feature on the Info pages will take care of this for us and you'll be able to tag/search with lucid, 10.04 and/or lucid-lynx and these will be treated as equivalent.
It's early days for that feature, so I see where you're coming from.
Comment: Agreed. we should only merge codenames for consistency i.e lucid and lucid-lynx and keep codenames and version numbers. different people search for different tags.
Answer: On the parent site there are (at this moment) 37 questions tagged with 10.04 and 9 questions tagged with lucid. Of the 37 questions tagged with 10.04, 5 are also tagged lucid and 1 is also tagged lucid-lynx.
It looks like thus far 10.04 is the popular choice and I see also the top voted answer to this related question.
I think it would make sense for the other two to be suggested as synonyms for 10.04. However, that decision is in the hands of the +1000 users (currently 7) or the moderators (I think).
Answer: I think so, although for readability I think that we should give preference to the codename (excluding the animal). For example:

lucid <= 10.04
lucid <= lucid-lynx

Etc.
Comment: The result of http://meta.ubuntu.stackexchange.com/questions/44/should-we-have-a-consistent-naming-scheme seems to suggest doing it the other way around.
Comment: The code names are confusing. It's hard to tell if they refer to the current release or not.

Merging codenames with versions


Are hairline cracks in basement concrete floor a problem if there's no water coming in?

Question: I notice quite a few hairline crack in my basement concrete floor. I've lived here for 14 years and no water has come up through the cracks. The townhouse was built in 1999 (so it is not a new pour). I don't know if the cracks have been getting worse or not; I just didn't notice them before, but maybe they were always there. Is this something I should get fixed (how)? Or is it possible that they won't get any worse and water is unlikely to ever come in, if it has not come in yet.
Comment: Seems like quite a different question - his floor was just poored, and seemed to be a big issue
Answer: Concrete slabs crack. Period. For this reason, "control joints" are often cut or tooled into slabs where aesthetics are a concern. They encourage cracks to occur along straight lines where they create less of a visual blemish and can better be accommodated by expansion joints in rigid flooring.
In your case, it's not likely a concern.
Answer: Hairline cracks are not a problem.  If they get to 1/4" at any point, then you probably need to have an engineer give it a look over.
However, not sure if radon gas is a problem in your area, but cracks in the basement will let radon gas seep in, so it would be worth your time and the money to purchase a radon gas detector.  You could probably call your city/county inspection office to see if radon gas is problematic in your area.
Answer: Welcome to crap construction in the 21st century, where nobody gets basements, just footings, and those that do get basements get 4" slabs on sand often above the frost line.
Whether water comes in is a function of the water table in your area and whether you have proper drainage on your property.
There is nothing you can do except install a sump pump. Don't believe the "crack repair" con artists.
Oh, wait you could jack the house up, bed the foundation with compacted gravel, use real foundation walls and pour a proper 6" foundation. Just kidding.


Is "After the Japanese student graduate from ...." grammatical?

Question: I wonder if this sentence is correct, and is there a better alternative for this sentence. The sentence is:

After the Japanese student graduate from the secondary school, he will have learnt 2000 Kanjis."
Answer: "Student" is a singular noun but "graduate" is a plural verb. You should either make the whole thing singular, "student graduates", or make the whole thing plural, "students graduate".
The article "the" in front of "student" makes the sentence refer to one specific student. I suspect you are talking about students in general. You could cast it in the singular and say "a Japanese student", or you could make it plural and say "Japanese students". That said, "the" is not necessarily wrong here. Sometimes English-speakers say "the student" to refer to a generic student. In a sense it violates the usual rules about "the" versus "a", but it's done fairly often.
I'd also guess that they don't learn the Kanjis AFTER they graduate, but rather they learn them while they are in school. So you should say "When a student graduates ..." or "By the time a student graduates ..."
So better phrasing would be:

By the time a Japanese student graduates from secondary school, he will have learned 2000 Kanjis.

Or

When Japanese students graduate from secondary school, they have learned 2000 Kanjis.

A catch to using the plural is that in some cases it may not be clear whether you mean that each student learns 2000 Kanjis, or that all together the students learn 2000 Kanjis, i.e. if there are 200 students they may learn 10 each. I think in this case the reader would assume that you mean each student learns 2000, but it could be unclear in other contexts. Like, "When the volunteers completed the job, they were paid $1000." Was each volunteer paid $1000, or were all the volunteers combined paid $1000?
Comment: +1 Very well explained. I also like that you added the note on the plural form being unclear in some contexts. I would +1 again for that if I could XD
Comment: I know it's a loanword but I think "2000 kanji" is more correct than "2000 kanjis".
Comment: Wow, my English became So bad, I don't know why! - thank you
Comment: @almousawi Don't worry. I don't know how long you've been speaking English. I've been at it for 55 years and I still trip up plenty often. :-)
Comment: @Jay hearing these words from a US resident sure is encouraging :)
Comment: @starsplusplus I suspected that before . I'll correct it.
Answer: "When the Japanese students graduate from secondary school, they will have learnt 2000 Kanjis" - sentence talks about all the students graduating from secondary school in geneal.
"When the Japanese student graduates from secondary school, he will have learnt 2000 Kanjis." - sentence talks about a single student graduating from secondary school, gender of student not important here.
Does this help you??


What is IQ in the context of SDRs?

Question: What is IQ, in the context of software-defined radios (SDRs)?
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/106892/discussion-on-question-by-geremia-what-is-iq-in-the-context-of-sdrs).
Answer: "IQ" refers to the practice of having two mixers with their oscillator phase 90 degrees apart, and then the digitization and processing of those two streams of data.
One practical problem is in a superheterodyne receiver, the LO must be selected and the filters designed for the best image response.
The problem can be understood intuitively like this: say there is a spinning disk, with a mark on its diameter. The disk is spinning so quickly it's a blur, but you can use a strobeoscope to observe it. You know approximately how fast the disk is spinning, and you set the strobeoscope to this frequency. It will then appear the disk is spinning slowly, with the speed corresponding to the difference in speed between the strobeoscope and the disk. Depending on the direction of spin, you can tell if the disk is spinning faster or slower than the strobescope.
If you separate the horizontal and vertical positions of the mark into functions, you will find they are the trigonometric functions $\sin()$ and $\cos()$, which are the same function but 90 degrees apart:

The problem is a single RF mixer operates like a stroboscope that only gives you the position of the mark in one dimension. With just one dimension you can tell the difference in speed, but you can't tell if that difference is positive or negative.
The mathematics of how this works is elegantly expressed in Euler's formula:
$$ e^{ix} = \cos x + i \sin x $$
It turns out this is really useful. The reason a frequency mixer has sum and difference frequency products is because
$$ \cos(x) = \cos(-x) $$
But if we allow the calculations to have complex values we can write signals not like this:
$$ s(t) = \cos(\omega t) $$
but instead like this:
$$ s(t) = e^{i \omega t} $$
and because
$$ e^{ix} \ne e^{-ix} $$
we no longer have that pesky issue of dealing with images at every mixing stage.
In analog hardware this is implemented by having two mixers. They each get the same RF signal, but their local oscillators are 90 degrees out of phase. This means one mixer (call it $I$) produces the $\cos$ component in Euler's formula, and the other mixer ($Q$) produces the $\sin$ component. After these signals have been digitized we can treat each pair of samples and the real and imaginary part of a complex number, and then go on processing them as if it's a single, complex-valued signal.
It turns out complex numbers show up in all kinds of DSP math. For example, the discrete Fourier transform (DFT) can be thought of as calculating the correlation of the input with a $\sin$ and a $\cos$ function at each bin. That means with Euler's formula we can consider the DFT to operate on complex numbers.
Also, many demodulation algorithms will involve shifting things up and down in frequency, and in the digital domain, just like the analog domain, if we do this only with real numbers then we have to be concerned with rejecting image frequencies at every step.
These are just a few examples. The point is generally IQ processing simplifies both the analog and digital implementations of an SDR.
Comment: Great answer. The part about complex numbers and real numbers in the last paragraph kinda comes out of nowhere -- might help to have a sentence to introduce that, something like *You can see that we can use complex numbers to model the two components, with real numbers in one dimension and imaginary numbers in the other.*
Comment: @Caleb thanks for the feedback, tried to make it a little better.
Answer: To just answer the literal question:
I stands for Inphase and Q stands for quadrature.
These are the two baseband signals you get when you mix the RF signal with a cosine of the carrier frequency, and with a 90° shifted version of that cosine, respectively (and properly low-pass filter afterwards).
We call the first the inphase component, because it is literally what you get in phase with the cosine.
Mathematically, mixing-and-filtering is an inner product on the vector space of $L^2$ signals (it's effectively the integral of the point-wise multiplication of two functions – the RF signal and the local oscillator). That is: it's a projection, very much in the geometric sense! That explains the name of the quadrature component, as it's orthogonal to the inphase component.
Being orthogonal also means, just like in geometry: no matter which length you have orthogonal to the other vector, the projection on that vector is going to be 0.
That is very important – it means that I and Q, respectively, are two signals that are, together, equivalent to the RF signal in what they contain in signal "content", but they are independent; no matter what you do to the I part, it doesn't change the Q part.
That gives us a way of understanding any RF signal around any carrier frequency by describing the equivalent baseband signal in terms of I and Q signals, which individually have half the bandwidth of the RF signal.
That is the strength of it – no matter to which carrier frequency your transmitter mixes its signal, the equivalent IQ baseband doesn't change (only the LO frequency).
And the same applies to all the nice linear channel models we have: You could describe what happens to your signal between your transmitter and your receiver by describing what happens at the carrier frequency – or you could do the same directly in baseband, and ignore the fact that you have a mixer to go up from baseband to RF, then some amplifier, an antenna, the air, another antenna, an LNA, a mixer in between and just describe all this as a channel on the baseband, mathematically (and SDR, being software, is very good at math).
Now, to do things mathematically with the baseband, it has proven elegant to associate complex numbers with the I and Q components: The complex baseband signal at any time $t$ is just $I(t) + jQ(t)$, with $j=\sqrt{-1}$, the imaginary unit.
Answer: If you're looking for just a basic definition, I/Q data is the result of a special form of sampling. Unlike "normal" sampling which takes a single measurement of a signal at each division of the sample rate, I/Q sampling gathers two measurements for each sample: both an "In phase" and a "Quadrature" component — thus the acronym.
The "quadrature" part only makes sense in a context where you are mixing the signals before sampling them. Although the ultimate signal of interest may be chosen selectively via software only, a typical SDR still gets "tuned" to a particular range of frequencies to start with. This is done by multiplying the incoming RF with an "LO" signal, similar to the first stage of an analog heterodyning receiver. The center frequency of the tuned-in range is determined by the frequency of that "LO" signal.
Now you can think of the in-phase component as the "normal" sample, and the quadrature component is equivalent to a second sample taken "90º later" in terms of the tuning frequency (i.e. delayed in time by 1/4 of the LO's period). In practice, both the I and Q "ADC inputs" would be provided simultaneously as separate signals from the mixer circuit, and the two components are taken together as a single "vector" sample at each point in time.
Capturing a two-component I/Q sample is more useful than just doubling the acquisition rate of "normal" [scalar] sampling. The vector I/Q samples are better for DSP processing because they avoid some ambiguity issues that come about in the mixer/heterodyning process. See Phil's comments below in response to an earlier version of this answer.
I found Whiteboard Web's I/Q Data for Dummies to be a great intro to the concept personally, as it works through questions like "why isn't normal sampling good enough?" at least from a processing perspective. (Especially now that other posters here have provided greater clarity on what it is trying to say… ;-)
Comment: It _does_ provide more information: with IQ sampling it's possible to know if a frequency component at the mixer's input is above or below the LO frequency. Not so by simply doubling the sampling rate: you end up with the same bandwidth, but the frequency ambiguity remains.
Comment: It still seems off, but I'm trying to put my finger on exactly what. I think it's that you say "90º _later_", implying you could achieve this 90 degree phase shift by waiting in time. It's certainly true in a lot of engineering we consider phase shifts and delay as the same thing, but that doesn't work here. A delay in time, like from adding a length of transmission line, can provide a 90 degree phase shift for only _one_ frequency. But in IQ sampling, the phase shift is 90 degrees for _all_ frequencies, because it's achieved not by adding a delay, but by changing the LO phase.
Comment: If you have GNU Radio companion, try making a demo for yourself: put a complex signal source with a frequency you can vary into a complex time sink, and look at how the relative phase between the real and complex parts changes with frequency. You'll see at _all_ frequencies, the two are 90 degrees apart, though which one leads the other flips as you cross over 0 Hz. There's no way to achieve that with a delay.
Comment: I see where you are hung up -- IQ sampling isn't just sampling sometimes and then sampling in between those points. It's not the phase of when you do the sampling that's significant, it's the phase of the _local oscillator_. Just taking more samples at a different time does not have the same effect as changing the LO phase.
Comment: @PhilFrost-W8II Hmm, trying to understand. (Maybe this needs a new Q&A but not even sure the question yet….) It sounds like I am wrong about what the 90º-off-phase is relative to — it's not the phase of the sampling rate, but the LO rate that matters? ~~How does this work with the "direct sampling mod" trick folks use with SDRs where there is no mixer?~~ Ah, I see that at least with the RTL-SDR when [direct sampling](https://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/) you have to choose either I **or** Q which I presume then gets treated as a "normal" sample to use my own terminology above.
Comment: Okay, not one but two rewrites later — more accurate now?
Comment: Or if you want to ask a question about why we can't make IQ samples by sampling twice as fast I can make that demo and post the screenshots
Comment: Gave it a shot at https://ham.stackexchange.com/questions/16495/how-can-quadrature-mixing-adjust-the-phase-of-all-frequencies-by-the-same-amount though I fear my misunderstanding may still be a bit too multi-faceted for a single question :-P
Answer: A Fourier series can represent a real-world signal as a weighted sum of harmonically-related sine and cosine waves. Sine and cosine waves are out of phase by one-quarter of a cycle and so are said to be in quadrature to each other. Thus, the weighted sums are known as the In-phase (I) and Quadrature (Q) components.
For example, single sideband modulation (SSB) comprises a Q component weighted by the Hilbert transform of the weight of the I component.  Digital signal processors (DSP) "do the math" to calculate the weights needed to produced the desired results.
Answer: IQ is a type of sampled data.  Sampled data (a vector of numbers) allows digital processing (a bunch of arithmetic on finite size numbers), instead of using analog circuits (inductors, capacitors, etc.), to produce some signal transform (for instance: filtering or demodulation, etc.).
IQ usually describes pairs of unequally spaced or offset heterodyned samples taken at a sample rate (per pair) frequency related to the frequency bandwidth of interest, often well below the actual RF frequency of the signal of interest.  Regular (non-IQ) sampling is taking equally spaced samples at a rate above (often well above) the high end of a (radio or audio) frequency band of interest.
To be considered a good IQ signal, the pair of samples need to be taken in quadrature (1/4, 3/4 time spacing), or be samples of a pair of waveforms that result from heterodyning by a quadrature mixer.  This allows the IQ data to be fed to a complex FFT, where the positive and "negative" frequency halves of the FFT result will not just degenerate to complex conjugate mirrors of each other, as would be the FFT result if the FFT was fed, real component only, with equally spaced samples.  Thus you get twice a much useful "stuff" out of a given length IQ FFT.
Comment: hm, not really a type of sampled data, I and Q (for Inphase and Quadrature) just describe the two analog baseband signals after mixing down with the LO and it's 90°-shifted version. Sampling usually comes after.

What is IQ in the context of SDRs?


ruby on rails with nginx configuration file

Question: I am attempting to get the nginx upload module working with my application.  I have modified the server block in the nginx.conf file and doing so throws a 403 Forbidden error when I attempt to access my website.  The logs say that the rails public directory cannot be accessed.
http {
passenger_root /opt/passenger-3.0.0;
passenger_ruby /usr/bin/ruby1.8;

include       mime.types;
default_type  application/octet-stream;

sendfile        on;
#tcp_nopush     on;
client_max_body_size 30M; #allow large uploads
#keepalive_timeout  0;

#gzip  on;

server {
    listen       80;
    server_name  url.com;
    root /path/current/public;

 # Match this location for the upload module
 location /images/fast_upload {
 # pass request body to here
 upload_pass @fast_upload_endpoint;

 upload_store /path/shared/uploads_tmp 1;

 # set permissions on the uploaded files
  upload_store_access user:rw group:rw all:r;

 # Set specified fields in request body
 # this puts the original filename, new path+filename and content type in the$
 upload_set_form_field upload[fast_asset][original_name] "$upload_file_name";
 upload_set_form_field upload[fast_asset][content_type] "$upload_content_type$
 upload_set_form_field upload[fast_asset][filepath] "$upload_tmp_path";

 upload_pass_form_field "^image_id$|^authenticity_token$|^format$";
 upload_cleanup 400 404 499 500-505;
 }

 location @fast_upload_endpoint {

  passenger_enabled on;
  rails_env production;
 }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   html;
    }

  }
 }

When I move "passenger_enabled on" out of the location block it works fine.  However it doesn't look like nginx takes the file uploads with that configuration in the .conf file.
Answer: location @fast_upload_endpoint {

     passenger_enabled on;
     rails_env production;
  }
location / {
 rails_env production;
 passenger_enabled on;
}

I added a second location block and it seems ok now.


Expectation of a Product of Martingales

Question: Given a non-negative martingale process $(X_t)$ with its natural filtration, what can be said about
$$\mathbb{E}(X_t X_{t+1} X_{t+2} X_{t+3} | \mathcal{F}_{t-1})$$
specifically can we say
$$\mathbb{E}(X_t X_{t+1} X_{t+2} X_{t+3} | \mathcal{F}_{t-1}) > (X_{t-1})^4$$
i.e. does it behave as a submartingale, without making further assumptions about covariances
Comment: I have made the typesetting better, is this the expression you have intended?
Comment: Indeed it was the expression I intended thanks a bunch
Answer: The answer is YES if one replaces $\gt$ by $\geqslant$ and if one assumes that $(X_t)$ has finite fourth moments. This is based on three simple properties of conditional expectation, namely:

(C) Convexity. (T) Tower property. (M) Taking out what is measurable.

(C) means that if $\varphi$ is convex and if $Z$ and $\varphi(Z)$ are integrable, then
$$
E(\varphi(Z)|G)\geqslant \varphi(E(Z|G)).
$$
(T) means that if $H\subseteq G$ and if $Z$ is integrable, then
$$
E(Z|H)=E(E(Z|G)|H).
$$
(M) means that if $U$ is $G$ measurable and if $UZ$ and $Z$ are integrable, then
$$
E(UZ|G)=UE(Z|G).
$$
Now we must estimate $Y=E(Y_1|F_0)$ with $Y_1=X_1X_2X_3X_4$.
First step
(i) By (T) for $Z=Y_1$, $G=F_3$ and $H=F_0$, $Y=E(E(Y_1|F_3)|F_0)$.
(ii) By (M), since $U=X_1X_2X_3$ is $F_3$ measurable, $E(Y_1|F_3)=X_1X_2X_3E(X_4|F_3)$.
(iii) Since $E(X_4|F_3)=X_3$, $Y=E(Y_2|F_0)$ with $Y_2=X_1X_2X_3^2$.
Second step
(i) By (T) for $Z=Y_2$, $G=F_2$ and $H=F_0$, $Y=E(E(Y_2|F_2)|F_0)$.
(ii) By (M), since $U=X_1X_2$ is $F_2$ measurable, $E(Y_2|F_2)=X_1X_2E(X_3^2|F_2)$.
(iii) By (C) for $\varphi:z\mapsto z^2$, $E(X_3^2|F_2)\geqslant X_2^2$.
(iv) Because every $X_i$ is nonnegative, $E(Y_2|F_2)\geqslant Y_3$ hence $Y\geqslant E(Y_3|F_0)$, with $Y_3=X_1X_2^3$.
Third step
Apply (T) once again, this time to $Z=Y_3$, $G=F_1$ and $H=F_0$, then (C) once again, this time with $\varphi:z\mapsto z^3$ (which is convex on $z\geqslant0$ and only there), then (M) once again with $U=X_1$, and once again the nonnegativity of every $X_i$, and you are done.
Likewise, for every $n\geqslant1$, if $(X_t)$ is integrable enough,
$$
E(X_{t+1}X_{t+2}\cdots X_{t+n}|F_t)\geqslant E((X_{t+1})^n|F_t)\geqslant (X_t)^n.
$$
The idea of synthetizing properties (C), (T) and (M) is adapted from Probability with Martingales by David Williams (see Section 9.7 Properties of conditional expectation: a list).
Comment: If you are making explicit use of the tower property, you should also state that you are using the fact that if $X$ is $\mathcal{F}$-measurable, then $E(XY|\mathcal{F})=XE(Y|\mathcal{F})$
Answer: I dont know much about martingales, but I'd say yes. Calling $a,b,c,d$ your $X_t ... X_{t+3}$ conditioned to the past $F_{t-1}$, and applying the formula $E(a b) = E(a E(b|a))$ we get that the LHS is
$E(a \; E(b \;  E(c \;  E( d | a b c ))))$  (the variables in each term are assumed to be contitioned on the past values).
The most inner term is $E( d | a b c ) = c$
The next resulting term is $E( c^2 | a b ) $ . As we know that $E(c | ab) = b$, this must be greater (or equal) than $b^2$
By the same reasoning, the next term must be greater than $a^3$,  etc.
Update: Didier's answer came while I was finishing this; he says the same, basically - and better.

Expectation of a Product of Martingales


Need help on pronunciation

Question: Words like 「滅入る」and 「翻る」I just cant understand. When I look at the spelling for えいる and がえる, it just doesn't match with what I hear. with えいる I hear "eh-E-ru", but since い extends え (I think it does) shouldn't it be "meeh-ru"? and with がえる I hear "gah-I-ru". but its an え so shouldn't it be "gah-eh-ru". This is all super confusing to me and I'm probably fundamentally wrong somewhere so any help is greatly appreciated. (I'm a beginner)
Answer: I don't know where you originally heard these phrases from, but you'd pronounce these as:

滅入る めーいーる meh-ee-roo
翻る ひーるーがーえーる he-roo-gah-eh-roo

It should be fairly straightforward. Perhaps in the quicker pace of daily ordinary speech the sound might slide or be compressed to the listener.
Answer: It's worth noting that while the えい vowel combination in kana can represent a lengthened え sound, it doesn't always - in some words, it simply represents the え sound followed by the い sound.  In the case of 滅入る, the kanji suggest that the め and いる are separate morphemes, so a "long e" pronunciation would be unlikely.
For 翻る, the vowel is definitely an え, but I can certainly see how it might sound like an い in rapid speech. The Japanese え in general is a little closer to い than the "bed" vowel of most English dialects is, and in vowel clusters like this the second vowel isn't always pronounced that distinctly.

Need help on pronunciation


One Polygon Joining to Database with Many matching records

Question: Using ArcMap 10.1.
Is this possible to have one polygon and join to a database/excel with many matching records?
I would like to have 1 polygon but match to 100 corresponding records in a table.  When I use the identify tool or select this polygon all 100 matching records would display?
Answer: MakeQueryTable will perform a one-to-many join from polygon to a table. It only works on a geodatabase, no shapefile support. Also, your excel/database table must be copied to the same workspace as the polygon features. The tool output is a feature layer, so you will want to save to disk with Copyfeatures.
Answer: I'm not sure that you can actually do a many to one join within a polygon. And, once you did I"m not sure exactly what you could calculate or do with it. But, a relate will link the polygon to your excel file and should make it so the records can be pulled up from the polygon. Here's esri's documentation on it from 9.3: http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=relating_tables


How can I keep lens filters and other attachments from sticking on the lens?

Question: Is there anything that can be used to keep filters/lenses/adjustment ring threads from sticking in the first place?
Answer: The main thing would be to keep them free of dust, dirt, and any sticky substances (eg oils).  The dust and other particles (eg metal shavings) are one major cause of these threads sticking, and the oils and stuff will contribute to these particles becoming stuck there.
You'll need to do this both for the lens and any filter you're going to screw onto it (or the camera body and lens back).

Use a cap over any lens back thread while it's not screwed onto a body.
Use body caps on bodies stored without lenses.
Keep any screw-in filters in a case while not screwed onto a lens.
Keep a lens cap over the lens when not in use.  However, this still exposes the front thread while you are shooting.  If you were paranoid, you could use a clear (UV) filter or a filter ring with no glass on the front and remove it when you want to attach a filter ... or just try to wipe any dust or grit with a soft dry cloth before attaching anything.

Another major cause of sticking is deformation of the thread, such as from dropping the lens.  If you have dropped your lens and slightly bent any of the thread, it may stick and that may be hard/impossible to fix.
You also need to be careful about what you screw into the filters - say you buy an old lens or filter from ebay, and the thread on that is damaged, that thread may then also damage the thread on the lens or body you're screwing it into.
Cheap accessories may also have deformities in the threads or be slightly misshapen from spec even when new.  This could be a problem.
Comment: And when it *does* bind, keep a rubber band handy as a removal tool.
Answer: The lower cost filters are made of Aluminium/Aluminum which has a very high thermal expansion coefficient compared to say Brass which the better quality filters and some lens bodies are machined out of. So the male thread of say, an Aluminum Polariser screwed into a brass UV filter or lens body on a cold day will expand when it warms up and hence be much harder to unscrew.
The other problem is that Brass and Aluminum, are very dissimilar metals and are well known to corrode when in contact, especially in seaside atmospheres.
So its preferable not to mix Brass and Aluminum components in the one stack.
Hope this is also useful grist for the mill.
Answer: Read this carefully, If you can get some lubricant on the thread (WITHOUT CONTAMINATING THE LENS OR FILTER ) this will definitely work.
Using a lens cleaning cloth, and while away from your camera and equipment, spray some furniture polish containing silicone on to the cloth, Then very carefully put your fingernail into a corner of the cloth and wipe around the thread making sure not to contaminate the glass.
I am sure there will be a lot of negative comments about this, but it does work and it is possible to do if you take care. I do this and it always works.
Answer: In my opinion the best things to do to avoid getting lens filter and adapters stuck on the lens are:

Use good quality filters and adapters. As it has been mentioned before, cheap adapters may be cheaply made and have imperfections and defects. You get what you pay for.
Don't over tighten them. Screw them slowly and carefully until you feel a bit of resistance as they tighten, then stop. Don't try to tighten them too much as it will make them harder to remove later on.

Now, if you have a piece that's stuck on a lens try carrying around something like this (http://www.amazon.com/Easy-Grip-Natural-Rubber-Jar-Opener/dp/B008W052RQ/ref=pd_sim_201_5?ie=UTF8&refRID=1AZ5JSXRPZ1385B166GN) It will give you a better grip on the ring and let you turn it with more leverage.


Chronological list of improvements in number of logical qubits

Question: Was wondering if anyone has any historical data/charts showing the number of over logical qubits over time. I am hoping to include something illustrative of Moore's law as applied to quantum computing for a presentation. Thank you.
Answer: I don't know if such a chart already exists, but I'd refer you to the Timeline of quantum computing on Wikipedia and the citations therein. It is quite comprehensive and you can extract the "number of qubits vs. time" data from there and create your own charts.
There's also this but it misses out on a lot of details (and is a bit misleading):

Nevertheless, I'd like to mention that the number of qubits by itself is not a good measure of the performance of quantum computers. And Moore's law is not really applicable to quantum computing. Please read through the following threads.

Is Google's 72 qubit device better than D-Wave's machines, which feature more than 2000 qubits?
How should different quantum computing devices be compared?
Does Moore's law apply to quantum computing?
Answer: I recommend you the Quantum Computing Report page, where several news about quantum computing and other interesting data about the quantity of qubits and quality of them in each existing nowadays is presented. The link I added refers to a post called "Applying Moore's law to quantum qubits" as you are specifically requiring such information.


When removing a lens, does Image Stabilization need to be turned off on the lens?

Question: I am taking a photograph course and the instructor, who repairs cameras, says it is extremely important to turn off the Image Stabilization on the lens before you remove it from the camera. He says turning it off "locks" things in place and prevents damage. Is this true? I have googled it and can't find any reference to this. I have a Canon 20D and Canon lenses. Thanks!
Comment: Uncle Roger at lensrentals dot com agrees with your instructor and cites his experience shipping hundreds of lenses thousands of times per month in the comments to [this blog entry](https://www.lensrentals.com/blog/2018/08/lens-teardowns-and-comparisons-of-the-canon-70-200mm-f2-8-is-ii-and-iii/) and at [this thread on DPReview](https://www.dpreview.com/forums/post/61579446)
Answer: the only time the IS elements are "moving" is during the focus process (when you have your finger on the shutter button and a couple seconds after) otherwise everything is locked in place. If this weren't true then moving the lens and camera with IS turned on would have the potential to damage the elements of the lens and that would defeat the purpose of the IS in the first place.
Your instructor is wrong.
[Edit] from the EF 100-400 F4.5-56L IS USM manual (page E-9):

The image stabilizer continues to operate after you release the shutter button, as long as the metering timer displays the exposure value. Never remove the lens while the image stabilizer is operating, or you could damage the lens.
Comment: Ignoring the lens side of the equation, you should be turning your CAMERA off before changing lenses anyway, which would remove power from the IS anyway... accomplishing the same load of BS the instructor is claiming.
Comment: There is an argument that rages on many a forum that you don't  need to turn the power off for lens changes either - I do though because it makes me feel happy :-)
Comment: You don't need to turn your camera off before you change lenses. This is a myth. See: http://photo.stackexchange.com/questions/6217/what-are-the-dangers-of-removing-a-lens-while-the-camera-is-on/6226#6226 for more detail... But feel free to continue the practice if it makes you feel happy!
Comment: @cabbey There's nothing in the 20D manual about turning the camera off when changing lenses, if it was important I'm sure Canon would mention it!
Comment: According to [Roger Cicala](https://www.lensrentals.com/blog/2018/08/lens-teardowns-and-comparisons-of-the-canon-70-200mm-f2-8-is-ii-and-iii/), you are wrong.
Comment: The link offers a quite persuasive argument that not "parking" an IS unit can lead to an increased risk of damage when transported. The head of the company that ships the same tens of thousands of lenses over and over cites empirical and observational evidence that it does. "The locked position is safer for transporting the lens. If it's not locked the IS unit can bounce around and cause damage. How big a deal is it? I can't say for sure, but maybe 1 in 1,000 shipments that come back with IS not locked are damaged. But the incidence is 0 in 1,000; or very close to that, with IS locked."
Comment: @Jay @Matt: the contact frying bit I was well aware of, but the conversation Matt and Itai had in that question about static charge and dust is eye opening. I'll probably still try to avoid doing it. But since @Shizam has proven that even turning it off isn't enough when he's around it probably won't matter much. :)
Comment: and note that with @kloucks' edit to add... turning the camera off would take care of that caveat.  ;)
Comment: @Michael C  - if you can't provide a comment that has pertinent information or offers a persuasive argument don't waste our time with your "comments"
Answer: This is incorrect. Modern image stabilization is achieved through a lens element that is moved via electromagnets. Since electromagnets need to be powered in order to work, removing the lens (and the power source) will effectively lock the element in place rendering any movement impossible anyway.
Having said that, there are a number of really 'old school' lenses that potentially would be damaged if the image stabilization was not turned off first because they used gyroscopic stabilization methods instead of electromagnetic ones and the 'off' button literally locked physical elements of the lenses in place. Not locking the elements meant that they just 'rattled around free' in the lens housing. You don't have one of these lenses, however... They wouldn't fit on your Canon 20D (or any other modern camera)!
Not trying to judge, but this may be a case of an instructor not bothering to learn about new technology advances and carrying forward bad advice because "that's the way it used to be," which sadly happens quite a bit...
Comment: *"Since electromagnets need to be powered in order to work, removing the lens (and the power source) will effectively lock the element in place rendering any movement impossible anyway."* Or it can leave them free to flop around with no electrical current to hold them in place. https://www.lensrentals.com/blog/2018/08/lens-teardowns-and-comparisons-of-the-canon-70-200mm-f2-8-is-ii-and-iii/ and https://www.dpreview.com/forums/post/61579446
Answer: From Roger Cicala's blog at lensrentals.com describing his teardown/comparison of the insides of the EF 70-200mm f/2.8 L IS II versus the EF 70-200mm f/2.8 L IS III:

Looking from underneath, though, you can see the plastic posts that we sometimes mention. These occasionally break, possibly from shock during shipping. If the IS is not turned off, the lens group is free to bounce in all directions with only the posts to stop the motion.

Both the version II (2012) and version III (2018) of this lens are identical in this respect.
Just because IS is not active and moving the gyros and stabilising elements does not mean the inner half of the IS unit is not free to flop around inside the lens.
Later in the comments section of the lensrentals blog entry Roger responds to a question from a reader and says:

The proper thing to do is 1) Turn IS off at the lens while the lens is still mounted to a camera. This 'locks' the IS unit in place. If you have IS on and just remove the lens from the camera, then it does not lock and off the camera flipping the switch does no good.
You can confirm by gently shaking the lens; there's very little noise if the IS is locked.
The locked position is safer for transporting the lens. If it's not locked the IS unit can bounce around and cause damage. How big a deal is it? I can't say for sure, but maybe 1 in 1,000 shipments that come back with IS not locked are damaged. But the incidence is 0 in 1,000; or very close to that, with IS locked.

In a DPReview forum discussing Roger's Blog entry, Roger answered the  question, "Roger - would that be the best practice for ANY Canon lens with IS? Turn off IS, then remove from camera?"

Yes. We do it with every one. The most obvious 'rattlers' are the 70-200 f/2.8 and 100mm f/2.8 IS, but it's good practice. We think it's so important that it's checked twice: once when it returns from rental, and as the last check again before it's packed for it's next shipping.
That being said, damage to the IS isn't frequent even if it's left off (for example, most customers ship them back unlocked), perhaps 1 in 1,000 shipments, maybe less. But for us that can mean several broken IS units a month.

If Uncle Roger says it's safer with Canon lenses to turn off IS and therefore lock it, I'm turning my IS lenses off before putting them away in my bag or case. YMMV.
Answer: Modern lenses are designed to be "idiot proof," else they generate too many returns and warranty repairs. It's a bad idea, but I have seen (and even done, on occasion) lens changes while the camera is on with no ill effects. Image stabilization doesn't need to be turned off on modern lenses (unless specifically stated in the documentation).
Panasonic released a Micro 4/3 macro lens last year that even rattles when not on the camera. Panasonic sent a notice saying not to worry, this is normal.
Comment: https://www.lensrentals.com/blog/2018/08/lens-teardowns-and-comparisons-of-the-canon-70-200mm-f2-8-is-ii-and-iii/


installing ubuntu on to a pc without an os with a usb stick

Question: im trying to install ubuntu onto a pc i have built that does not currently have an os on it, i have followed the ubuntu instructions to make my usb bootable. in my bios i have the option to boot from four different USB-ZIP USB-HDD USB-FDD and USB-CDROM i have tried all but to no avail when i load up my pc without going to the bios it comes up with basic info about the flash drive and a bunch of stuff below, then below this it shows the drives it has tried to boot from and always comes up with boot error. I need some help.
Comment: Please add the error message you are getting.
Answer: Sounds like your USB drive is not bootable. Maybe try downloading the .iso again (make sure you get 32 or 64 bit depending on your hardware).
There are applications that make the drive bootable for you, Universal Pen Drive is a good one. Just copying a .zip or .iso onto a USB drive does not make it bootable.
After re downloading Ubuntu and making a bootable usb, hold down f12 (or option depending on your hardware) and it should pull up a list of bootable drives.
Another thing to check is the format of the USB drive before you try to put ubuntu on it, I'd use Fat 32.


Is it possible to set up blog categories without changing permalink structure

Question: When our blog was initially set up, the permalink structure used was /blog/%postname%/  We've had it that way for about a year now and have good SEO results.  We want to create a press release category for the blog which should result in a permalink like /blog/press/%postname%/  But doing this breaks all of our SEO links.  I know that we can use a plugin to create 301s for the broken links... but I'm just wondering if there's another way to do this?  Thanks.
Answer: https://wordpress.org/plugins/category-posts/ try this one - I think this is should work for what you are trying to accomplish
Comment: Thanks but it looks like that only allows me to create individual permalinks.  I'm not seeing a way with it to resolve anything at oursite.com/blog/press to a blog style page listing all posts with the press category.
Comment: Hi Geoff - sorry I misunderstood your question. I changed my answer with a plugin that should do what you are asking for. I believe you can use the shortcode to make just the posts from the category you want to display show up.


Formatting should not count towards the character limit on comments

Question: This is a minor frustration, but I have a comment that I put italics and bold into (using asterisks.)  Now I know I just just be happy that I could do it at all, but it seems to me that those should not count toward my comment char limit.
Comment: Much more of an impact are links; the whole URL and brackets/parentheses count towards the limit
Comment: With so many repeated paths, that comment could easily have been shortened. You also could have split it into two comments.
Answer: We need the formatting chars to count so that we can put in comments of less than 15 chars.  Please don't blow it for us.
Comment: **
Comment: See, @Chacha's comment shows up as a big blank area. Mine doesn't show anything at all.
Comment: I used to use \`             \`, but they fixed that one :(
Comment: @mmyers: Interesting, they appear identical on Chrome 6.0.408.1.  What are you using?
Comment: I see the blank space in IE8.
Comment: I have IE7 here at work. I'll check on Opera when I get home. @The
Comment: IE8 at the office, and Firefox 3.summat here render nothing for mmyers, and a blank area for Chacha.
Comment: Opera 10.53 also shows blank for Chacha. @cco @The
Comment: Safari 5 doesen't even show a space - just the "–".
Comment: Upvote for the humor, if it is :))).
Answer: Links are my biggest problem, and the one least under my control.  If a URL has a long link none of the options are ideal...

Don't link to it, reducing the utility of the comment.
Obsessively trim the grammar to get more space, which is no fun & can garble meaning.
Use a URL shortener, risking it becoming obsolete.
Trim that whole section of the comment, losing content.

Assuming the purpose of the comment character limit is to discourage long discussions in comments (and encourage you to make them answers), it seems the limit should be more concerned with the information density of the comment rather than its raw character count.  Regardless of the technical limitations, it would be useful to discuss this in principle.
Answer: Since Don't make URLs and title attributes count towards comment character limits has been marked a duplicate of this question here, please keep link target URLs in mind when you think about "formatting". For example (constructed but similar to real-life situations I encountered):

You can use a SaxSource constructed from an InputSource if you want to transform a SAX event stream.

is too long by 10 characters. Since I'm very much of the opinion that adding detailed links to all the pieces of documentation that you refer to makes not only questions and answers but also comments more useful and valuable, I think doing so should be encouraged. Having to delete links later on because the comments turns out to be too long is rather encouraging me to leave them out in the first place, which I consider harmful. So while I don't have such a strong opinion on other formatting, I'd very much like to at least discount link target URLs since those can easily dwarf an otherwise really short comment.
Answer: In a perfect world... yeah, I agree.
In this one though, that sounds like the sort of thing that would be rather problematic to implement. Either write shorter comments, or push for a larger character limit...
Comment: What about links? They take up a large chunk of the charlimit. Though its not too pressing, when a bunch of links kills my charlimit, I use multiple comments :)
Comment: I don't see how it would be "problematic" to implement. it is totally solvable.
Comment: @vsync probably right, just increase max size but still check 600 against the markdown result instead. Reading the markdown result as new text should be possible, you see that when you copy and paste comment text in a simple editor.
Answer: Six hundred characters isn't enough to include your content plus formatting?  That Should Be Enough For Anyone™.
That particular comment could be done as an update to the question, where it would be much more readable.  View source to steal:

Update: Regarding pm.h as ctacke points out, I must have something funny going on. I have 5 versions of pm.h on my machine and none of them have POWER_STATE_BACKLIGHTON in them. I am using VS 2008. They are located at:

C:\Program Files\Windows Mobile 5.0 SDK R2\PocketPC\Include\Armv4i
C:\Program Files\Windows Mobile 5.0 SDK R2\Smartphone\Include\Armv4i
C:\Program Files\Microsoft Visual Studio 9.0\SmartDevices\SDK\PocketPC2003\Include
C:\Program Files\Microsoft Visual Studio 9.0\SmartDevices\SDK\Smartphone2003\Include
C:\Program Files\Windows CE Tools\wce500\Windows Mobile 5.0 Pocket PC SDK\Include\Armv4i
Comment: Not if you're using links, it's not!
Comment: It's not enough: I often have to remove (very handy) links to stay under the limit.
Comment: Though those sentences could be better phrased; I paid attention to the formatting and pretty much ignored the content of the SO question... ;)
Comment: I wish I could format the spacing in my comments, but until this is done (never) I think you have the best solution.
Comment: Why not simply stick to the markdown result length as the length that counts?
Answer: How many formatting character do you propose to use out of 600ish in you answer, man?
I mean, I routinely use 4--8 in a long comment, but that is of close order 1%.
Surely you can tighten up you prose enough to make that big a difference, and if you can't you're trying to cram too much into a comment.
Comment: Why not simply stick to the markdown result length as the length that counts?
Answer: I suggest adding an "off topic" button next to each answer/question which will open a different chat UI where people are free to write whatever, when discussing things which should not be written as comments, but long internal debates over something.
Comments should stay short, because they are meant to be helpful to readers and not be used for long debates


Geth synchronization

Question: I downloaded geth and i've been waiting almost 3 days for the synchronization to finish. I've used the commands geth --fast --cache=512 --maxpeers 75 --jitvm. When geth is done downloading and syncing the blockchain does it show you a corresponding message or does it keep on downloading the new blocks? How do i know how much time left until it finishes?
Comment: See http://ethereum.stackexchange.com/questions/2853/geth-node-starts-to-sync-from-the-beginning-after-fast-sync/3060#3060 for the messages you will see when `geth` is syncing normally, or fast. Fast syncing should take a few hours on a fast internet connection and a solid state disk. If you are not fast syncing, you may want to consider removing the old chaindata and then restarting the fast sync. After the full sync, it will continue receiving new blocks produced on the network.
Answer: When geth log messages report a lot of blocks synced, it means node is not yet in-sync:
I0131 17:01:56.395603 core/blockchain.go:1042] imported 1560 blocks,  1610 txs (370.754 Mg) in    8.291s (44.715 Mg/s). #375988 [01c14ed2⦠/ 5fae052fâ¦]
I0131 17:02:26.547951 core/blockchain.go:1042] imported 1860 blocks,  1878 txs (359.007 Mg) in    8.042s (44.639 Mg/s). #382432 [b37e663e⦠/ 43a0e456â¦]

but when they report just a few, it means it is synced:
I0206 13:20:32.849694 core/blockchain.go:1042] imported 1 blocks,     2 txs (  0.317 Mg) in  26.183ms (12.105 Mg/s). #483939 [7db3a92bâ¦]
I0206 13:20:45.187344 core/blockchain.go:1042] imported 1 blocks,     8 txs (  0.489 Mg) in  23.943ms (20.431 Mg/s). #483940 [32455099â¦]
I0206 13:20:58.534970 core/blockchain.go:1042] imported 1 blocks,     3 txs (  0.286 Mg) in  11.536ms (24.834 Mg/s). #483941 [6a6e35b4â¦]

Besides, you may check the block number at the end of the line. If it is the same as last block according to the blockchain browser ( https://testnet.etherscan.io/ ) , it mean your node is synced.
Comment: Thanks for your input. however the blocknumber is much greater than the last block on testnet.etherscan `I0206 15:45:32.254938 core/blockchain.go:1070] imported    1 blocks,     1 txs (  1.400 Mg) in 13m5.867s ( 0.002 Mg/s). #2325301 [88dae063…]` do you know why that is?
Comment: how do I sync with the testnet through geth? do i have to delete all the mainnet db that has already downloaded?
Comment: Maybe your node is syncing mainnet. https://etherscan.io/ Right now on block #3,133,876
Comment: I don't know if it is relevant but on the mist wallet i am up to date with the last block on the testnet
Comment: You may store two blockchains on disk, but geth node will sync just one of them: testnet or mainnet. They are stored on differente folders, so they don't interfere.
Comment: To sync testnet instead of mainnet, just add --testnet to the geth launch command

Geth synchronization


Low Salt Indian Food

Question: Indian recipes tastes awful with reduced salt. Can anything be done to make them more palatable? Are there dishes that taste OK even with low salt?
Comment: Don't put salt in your food? Salt is not often a required ingredient
Comment: I'm sorry, but one of the few types of culinary questions we don't entertain here are recommendations/suggestions/ideas. See the [faq#dontask] and the meta question ["What should i cook" type questions](http://meta.cooking.stackexchange.com/q/1124). As TFD says, just pick any recipe and don't add salt.
Comment: > Don't put salt in your food? Salt is not often a required ingredient

The food then tastes awful. That was the reason for the question.

> one of the few types of culinary questions we don't entertain here are recommendations/suggestions/ideas

I was looking for a solution to a major food problem for me (and not what should I cook).

> As TFD says, just pick any recipe and don't add salt

The food then sucks.
Answer: Indian recipes taste fine with reduced salt, as long as you haven't trained your palate to enjoy salty food. This is no different to any other regional cuisine.
I personally cook curries with no added salt at all, a quarter-teaspoon of salt per portion of boiled rice, and minimal salt in breads.
Try reducing saltiness gradually, until your palate no longer demands it.
In the meantime you could use salt substitutes - there are products made with potassium chloride instead of sodium chloride which may be better for you than salt.
Answer: One (helpfully, authentiacally Indian) practice that might prove useful to you is, cook the food with even more reduced salt, or no salt at all - then, when serving, add just the amount of salt you want to eat in the meal to your plate in a separate little heap.  The practice is used to adjust the salt you need by taste, by dish, or even by bite (since it was easier than trying to salt food made in large quantities to everyone, everyone's taste).
In any case, having a few grains of salt sprinkled directly over the food as you take a bite (or nabbed by a damp finger or spoon edge and set on the tongue) can flavor the bite as boldly as a full pinch mixed into the same bite.  It hits the tongue directly, it gets all the salt immediately available to your taste buds, instead of spreading the salt through the food so whatever surface hits the tongue has enough salt for the bite, and you may not miss the extra salt as you're chewing because your tongue is convinced there's enough salt already.  Think about food where flakes of sea salt are sprinkled on top - because it is immediately available, it tastes much saltier than the same amount of salt mixed cleanly into the food (I'm thinking slated chocolates or caramels).
As a side note, you may miss the salt less in milder dishes, since you won't need the salt as much to balance out the heat and other flavors.  But that's a question of personal taste.
Comment: Thanks for this advice, Megha. This (salt sprinkled on top being immediately available) does seem to make a difference. (Note: I only saw this comment a couple of days ago, i.e., a year late.)
Answer: Indian dishes are about rich flavor and balance of sweet(jaggery /sugar), sour(tamarind),spicy(chilly) and salt. If u miss or reduce even one of these, you throw the balance off. If you are going to prepare an Indian dish add salt as much as the recipe calls for.
Answer: About indian food i couldn't say anything. But since you are asking here, I imagine that you can accept different suggests also.

generally the meat does not need salt (if using meat), because it contains enough
get your salade using soy sauce instead of salt
cook the vegetables using extract of meat or vegetables (with a bit of water) instead of salt
use many spices, especially Mediterranean herbs, in cooking, that being the tastiest require less salt or even they can do without.
use as a sauce for spaghetti or rice, tomato sauce with lots of basil, sauce "pesto", tuna and anchovies sauce, dry tomatowes sauce. Those sauces are very tasty, but precisely because of this, it's enough just a very short for season: with a couple of teaspoons you have a great dish
use "strong" vegetables in preparations, such as garlic, onion, celery
prepare many dishes complete, cereals and legumes, such as pasta and beans, rice and peas, pasta and chickpeas, always seasoned with many herbs.

Finally, think that you get used to everything. I know people who could not eat salt for years, and now they find inedible normally savory dishes.
Comment: Question is specific to indian food, which needs a certain (not: extreme) amount of salt exactly because there are large amounts of herbs, spices and vegetables - which makes for a highly-aromatic, high-bitterness, low to medium umami taste profile that is very dependent on some saltiness to balance that.

Low Salt Indian Food


Why would a Virus want hidden files to be shown?

Question: What else besides a virus would keep turning on "Show Hidden Files" in WinXP discusses the possibility of a virus setting the show hidden files values to true.
Why would a virus do this?  I would think it would want to make itself a hidden file then always set show hidden files to false.
Answer: Well it would show system files, which a user is not used to seeing. They could interpret these new files as part of the virus on the PC and try and delete them, causing more problems.
Although most viruses do this the other way around, they will attempt to hide files that it created on your system to deter their removal.
Answer: Sloppy coding.  Trying to hide it's files, but showing hidden files at the same time because that's what the author has on his system and he mindlessly copied the same setting across without thinking that not everyone will have it set.
Just because someone writes a virus, it doesn't mean they're a good coder, or that they know their way around windows internals.


Make Pepperoni out of Regular Salami

Question: So, i really love pepperoni pizza, and want to make it at home. However, in my city, i can't find pepperoni for sale in the market (i don't live in the US). So, i was wondering, can i make something similar to pepperoni by seasoning regular salami? If the answer is yes, what seasonings should i use? I thought of paprika and oregano, but i think that there's must be more into it. Any advices? Thanks!
Comment: It might not be quite the same ... but if you can get pickled hot peppers in your area, you can add those to the salami pizza and see how you like it.  Or shake some crushed red pepper on it right after it's out of the oven.
Answer: Pepperoni is basically just a spiced pork and beef salami with some smokiness in it, you could achieve a similar flavor by using some smoked chili powder like paprika or chipotle. You also aren't going to get very far trying to make a salami spicy by adding pepper to it beforehand, like injecting it with some sort of spice mix as there's not enough moisture to allow the spice to mix in. You'll have to add spice to the sliced salami, the question is how to apply that seasoning so the flavor seems to come from the salami when eating the pizza. Chili powders will burn in the high temperatures of a pizza oven, producing off flavors and an unappealing look, so sprinkling them on top of the salami slices is not the best idea.
You have 2 good options:

Add the spice to the pizza sauce: this will make the whole pie taste of the spice and may not be what you want. It's the quickest and easiest solution though
Rub one side of each sliced salami piece with the spices, and then put them on the pizza spice side down. This will localize the spice around the salami slices, and put the salami between the spice powder and the heat source so it doesn't burn. This is a bit of extra work but I can't imagine it being that big a pain

Personally I'd go with option 2 as you'll get a nice hum of spice around the salami and some on it when you bite. It won't be quite a pepperoni but I bet it will be very close.
Comment: I didn't suggest cutting slices and rubbing spices in a couple of days ahead of time because the slices are likely to dry out before they are used. I personally wouldn't use a flavored oil because a pepperoni (or salami) pizza is already pretty oily to begin with, but depending on someones taste it could work
Comment: I'd go for (1), but if doing (2) I'd dab the slices in a spice blend before putting them on, rather than sprinkling.
Comment: You could also try rubbing the spices into the pepperoni a day or two ahead of time.  I'm still debating if a oil & spice marinade would work.  And I'd probably go with a blend of smoked paprika and cayenne ... or just crushed red pepper.
Comment: good point @ChrisH, I've changed sprinkle to rub in my response.
Answer: You can marinade salami in the pickling liquid of canned pepperoncini around 10 minutes for that slightly off-sour taste and bite. Just drain it thoroughly and pat it dry before using. The acid helps permeate the fat content of the salami.
As GdD suggests, you could add a teaspoon of smoked paprika and chipotle powder to the mix to give it that depth, and a bit more kick.
Answer: Trader Joe's Bomba sauce (roasted Calabrian peppers), olive oil, smoked paprika...let it marinate with salami for a few hours=best pepperoni/chorizo ever!!!
Answer: This might be really difficult to get hold of where you are, but I can fool people into believing there's hot, spicy chorizo in a dish by using Canarian red Mojo powder. Add that to a salami & I'm sure few could tell the difference - so long as it's a Southern-European-style salami, not like a traditional Danish, for instance.
It's a dried blend of red chilli, garlic & cumin. It is traditionally made up into a sauce with oil & vinegar, but that's not necessary for this.
Though the ingredients would seem very simple, it does have quite a specific flavour profile, that just those few ingredients would not hint at in themselves. Because of this, I'm uncertain if making your own would come anywhere close compared to the real thing.
You may be able to get the Cuban variant, but I have never tasted that so cannot comment on its similarity or otherwise.

Make Pepperoni out of Regular Salami


Local printer redirection problems in Terminal Services

Question: I have several WinXP clients that are connecting to a Win2003 Terminal Server. I've had trouble getting them to map their local printer into the Terminal session.I have tried so many things but only one client can map its printer to terminal session. I have done this things at this article => http://blogs.technet.com/b/askperf/archive/2007/08/24/terminal-server-and-printer-redirection.aspx
Comment: Printer redirection under 2003 really doesn't work well.  There are 3rd party clients that make it better by doing some translation client side.  Are you willing to spend some cash?   Windows 2008 has Easy Print which also works much better.
Answer: Are you getting the event error indicated in that article?
Type: Error
Event ID: 1111
Description: Driver drivername required for printer printertype is unknown. Contact the administrator to install the driver before you log in again.
That is the usual cause i have seen for this. The driver has to be exactly the same for it to be picked up.
What i have done in the past is to create the printers as local printers on the terminal server and secure them with security groups. This has the benefit of not having to rely on the printer mapping each time. If you are going beyond one or two servers though then the admin overhead starts to cause problems.


Boxing vs karate for self-defense?

Question: Boxing vs karate for self-defense , Which suits well for self defence in real life situation ( such as blocked by a robber in night at empty street).
Comment: Possibly related question: http://martialarts.stackexchange.com/questions/3135/best-to-learn-for-self-defense-wrestling-boxing-or-jui-jitsu?rq=1
Comment: -1. This read like almost (but not quiet) a [Gorilla vs. Shark](http://blog.stackoverflow.com/2011/08/gorilla-vs-shark/). Also, "real life situation" is so vague as to be meaningless. Self defence is not street fighting.
Comment: Just a generalization, but it seems to me, that a young karate person is overconfident.  I think this passes, after about five years of it, but they feel like they can do more than they can.  My tkd instructor got jumped by three guys at 2 in the morning.  All three made a trip to the hospital.  Maybe the real answer is: whoever has better instincts, reflexes, training, and experience.  Martial arts are more on the theory side, while boxing has more of simpler moves drilled into your head.  Martial artist know a lot of moves, but have they practiced them to the point of a real life situation?
Comment: Whether it's boxing, karate, or baritsu, there are great instructors, awful instructors, and any number of gradations in between. Same is true of martial arts schools and training partners.
Comment: Asking "Which is better" is one of the least productive questions to ask on StackExchange.
Answer: Karate
Pros

More techniques = more options
Actually addresses self-defense as a concern.  May contain scenarios specifically geared toward self defense situations.  Depends on school.  Ask.

Cons

More techniques = less time spent training each technique.
Tends to emphasize fitness less than boxing.  This varies from school to school.  Ask/Observe a class.

Boxing
Pros

More time spent developing the few techniques you will use (basic punches: jab, cross, hook, uppercut).
Emphasizes fitness.  Fitness is important in many situations, including self-defense.
Trains more often than karate in a semi-live situation.  In this context, semi-live means that two contestants are actively trying to hurt one another.  This does not approximate a self-defense situation, but does teach combat awareness.  You will learn to take and give hits, and not freeze when confronted with physical violence.

Cons

Fewer techniques than Karate.

Analysis
Need more data.  Does the Karate dojo emphasize fitness? They tend not to, but there are exceptions.  Fitness is usually far more emphasized in boxing, and is an important part of self defense.  Does the Karate dojo emphasize semi- to full-contact sparring?  If so, another check in its favor, since this is something boxing does early and often.  If it both emphasizes fitness and sparring, choose the Karate dojo for its more varied techniques.  Understand that one technique practiced to the point of failure is more valuable than many techniques that are practiced half-heartedly.
A word on sparring.  I have included it as a criteria for the combat awareness that it trains, but understand that sparring, whether boxing or in karate, is not fighting.  It is impossible for a boxing school or a karate dojo to practice fighting, since fighting means actively trying to injure (not just cause pain) each other.  In sparring, for example, you will feint, throw combinations, back off.  That is not the way self-defense scenarios are fought.  In self-defense scenarios, you may face multiple, possibly armed attackers, and the arena will not be cushioned or padded for your safety.  It will be best if high-stress self-defense scenarios are engaged in.  You may find these in a karate dojo.  You won't find them in a boxing school.
Finally, you could do both.  They cross-train very well with one another.  At the very least, try both.  One thing I find is that martial artists are often trounced by well-trained boxers because martial artists do not tend to train as hard as boxers.
Comment: Good answer overall but I would emphasis that self defence is not limited to fighting. Although, that might be just me... ^_~
Comment: That's a good point.  Fighting is the last part of self-defense.  Self-awareness, environment-awareness, and preventative measures should come long before the fight.
Answer: I've been trainging in Kyokushin Karate for 15 years now and what I've learned the most, is that even if you master your art, self awareness is always the first thing that will get you out of a situation that can turn bad.
It's always better to avoid the situation than to be forced to deal with it.
Don't forget : adrenaline rush, stress and other factors can and will affect your capability of defending yourself once you are put in dangerous situation.
I don't think any art is better than the other, it just depend on how you put yourself into it.
Stay Safe !
Answer: With The Wudang King's excellent answer I can determine that Karate is more suited for self-defense because the techniques that are taught in karate are generally mixed so their is an emphasis on boxing, kick-boxing, ground grappling, open hand sparring and many self-defense drill simulations that the instructors provide to mimic situations such as: a man wields a knife in front of your throat, a man attempts to choke you out by surprise using a rear naked choke or even a man wielding a loaded gun is pointing a gun in front of you.
In karate you are able to learn more self-defense situations that boxing doesn't provide. The good thing about learning about karate is that each instructor has a different style of fighting, so it increases the spectrum for self-defense.
Boxing on the other hand does emphasize on a few techniques and a copious amount of power that is not viable for all to learn due to physical age and disabilities; with karate contending to the mixed martial arts aspect, your able to practice many self defense scenarios and learn many techniques while using little power to increase damage to your assailant.
My daughter has been learning karate when she was in 3rd grade and she enjoys the fitness, techniques and the training simulations. I recommend committing to karate for self defense, but similar to The Wung Dang Kid's answer your must ask the studio instructors on what aspect that they emphasize greatly. It can either be practical, situation, or sport based training. Look for situation based training to learn self-defense on the streets.
Hope this helps!

Boxing vs karate for self-defense?


Origin of heavier elements on earth?

Question: Earth is part of Solar system, which is said to have originated from condensation and mutual attraction in dense clouds of gasses and dust. If Sun is basically more than ninty percent hydrogen and rest is helium. Nuclear fusion inside sun is said to pause near iron(56/26) and also several other planets like Jupiter and Saturn are gas giants. Where did heavy metals and other heavy elements on earth come from if second most nearest star(/star-system) is some four light years away (and mass would take long to come from those sources) ?
Comment: Nuclear fusion inside the Sun currently stop at producing helium, not iron. In another 7 billion years the Sun will have exhausted the hydrogen in the core and become a red giant. Fusion will still stop at hydrogen producing helium, but in a shell around an inert helium core. Eventually, the Sun will start burning helium, when fusion will stop at producing carbon and oxygen. Our Sun is not the source of the non-hydrogen elements in the solar system's planets. Other stars that died before the Sun formed are the sources of those elements.
Comment: Consider that your reasoning, if taken far, goes to the concept of big bang. As for the question, nothing could be where it is. ...  I will answer later if no user do so.
Comment: The elements on Earth were not made in the Sun. The hydrogen was made in the Big Bang, the other elements were mostly made in other stars. See https://astronomy.stackexchange.com/q/16311/16685 Some of the elements were made by radioactive decay & other nuclear processes here on Earth.
Comment: The next nearest star is 4 ly away **now** but the stars move around over long timescales.
Answer: Different types of stars are responsible for creating different groups of elements via nucleosynthesis. Most of the "lighter" metals (Na, Al, Ga, Ge, Se), were formed by exploding massive stars, and most of the "heavier" metals (I, Ir, Ag, Au, Pt, U, Pu) were created by merging neutron stars. Exploding white dwarfs are partially responsible for elements like Ti, V, Cr, Fe, Co, Ni. Dying low mass stars were involved with the creation of some of the elements Sr, Y, Zr.
The following periodic table of elements (from Wikipedia), shows the elements color coded according to their source of creation.

All the elements on Earth were created by various stars that seeded our region of the universe prior to the formation of our solar system.
Comment: Good general answer but overlooks radiogenic isotopes. There's no primordial radon, for instance.
Comment: I just looked it up: most terrestrial helium is radiogenic too!
Answer: A very quick answer -- someone else may have a better and more referenced one. The heat of the newly formed sun drove the light elements away from the inner system (mostly). The rocky planets formed from what was left, the relatively small proportion of heavier elements in the dust and gas. Those elements were there at all because previous generations of stars, some much larger than the Sun, as well as violent events like neutron star collisions, had released them into space, contaminating the primordial clouds of hydrogen and helium.
Answer: Supernova ejecta expand at velocities between 5,000 km/s and 30,000 km/s.  Lets take 10,000 km/s as typical.  The speed of light, c, is 300,000 km/s, so 10,000 km/s = c/30. So, it would take 120 years for metals from the nearest stars to get to the Sun.  How much time was available?  Star formation in galaxies was well along 1 billion years after the Big Bang, 12.7 Gyr ago, and the Sun is 4.7 Gyr old.  So that gives 8 Gyr of travel time for debris from the first massive stars which become supernova in less then 100 million years.  Thus, the traveled length of the debris is 8 Gyr * c/30  is about 270 million light years.  In other words, there was sufficient time for supernova debris from our galaxy and hundreds of other galaxies to reach the solar protoplanetary nebula.  The story of course is different for the metals that come from progenitors that are not massive stars because of the longer delay for them to form.
I should add that the debris is likely to encounter intergalactic material along the way which will eventually halt its motion.  So realistically material will rarely move quite that far.
Answer: From an analysis of a certain type of Gamma-ray burst (Short, Hard GRB's) it is speculated these are caused by merging neutron stars.  It is also theorized that 2 merging neutron stars can create elements, some of the heaviest ones included.  This may have increased the amount of gold and other heavy elements on earth. These merging neutron stars also cause the r-process to create heavy elements due to a large number of neutrons.

Origin of heavier elements on earth?


What are some software examples to sketch out a website or app UI, updating the content is irrelevant and can remain static

Question: I have been working for a couple months on a new website/app idea. I have finished the design process but now I need to create a user friendly demo to show to people to gather some data/feedback and eventually demo it to investors. I am looking for a good software to design the UI. I'd like to focus on how the buttons, links, labels, text-boxes work together, ignoring the content (it can remain static) Any suggestions? Thanks!
Comment: What do you mean by "best"? Please remove the word "best" and replace with more specific terms, thanks! Also, it is OK if everything is static, for instance a news feed always shows the same news, and nothing can be modified or posted by the user?
Comment: Also, please limit your question to websites, otherwise it is far too broad. Then ask us to reopen.
Comment: It is ok if the website is static, it will only be used as a design proposal. I worry more about it properly showing how the buttons and text-boxes and those (UI) elements work together. The content is irrelevant.
Comment: Thanks! Finally, what is your budget? Must it be gratis for instance? And should the website be responsive design, I mean show cleanly on both desktop and mobile, or will you create a separate website for mobile if needed?
Answer: Take a look at Adobe XD. It is a drag-n-drop prototyping application for mobile apps and websites. It is intended for designers that have no programming experience, and it really is amazing how powerful it is for creating a professional prototype.
Adobe offers XD for free, so you can download it and do the tutorial. You'll see how easy it is to make something impressive in ten minutes.
Comment: I like how you are able to display how the buttons, textboxes and all those UI elements work together without focusing too much on the content. Perfect for a design proposal.
Comment: @elias Glad I could help!
Answer: I recently worked on a project where the designers used Invision. So I didn't create the designs, but I was able to comment on the designs and make change requests. The designers were not developers and only did interface design and mockups with invision.
So you could do a mockup without programming anything and present the basic app to investors.
https://www.invisionapp.com/
Answer: It depends on what technology stack you want to use long term.
Back in the day, I would simply use Visual Studio to develop my wireframes, which allowed me to transition from wireframe versions to functional software very quickly.


Encrypted traffic and amateur radio

Question: Am I allowed to send encrypted traffic via any medium or any frequency, or is this completely barred (and thus everything has to be open with no exceptions?)
Comment: A good answer would probably describe the global situation. Encryption is generally barred, except for a couple countries and specific exceptions.
Comment: Crypto may be required for error detection / correction and technical experimentation is welcome. I'd suspect you can get away with it if you publish the keys in internet. Event better if you prefix your transmission with info/URL e.g. in CW. I'd be interested.
Comment: @oh7lzb global answers are difficult, if not impossible. [What should happen to regional questions that don't specify a region?](http://meta.ham.stackexchange.com/q/120/218)
Comment: @jkj You don't always need to publish your private key. Error detection, correction, or digital signature does not always make the message unreadable. If the message is still in cleartext (there are exceptions, e.g. spread spectrum communications, or when encryption is used for authentication due to technical reasons, that require the key to be published). Using crypto like RSA or HMAC to sign/authenticate (not encrypt) messages is perfectly acceptable, as long as the protocol is published, e.g. here's a software package for signing AX.25 messages.
Answer:
11(2) The Licensee shall only address Messages to other Amateurs or to the stations of those Amateurs and shall not encrypt these Messages for the purpose of rendering the Message unintelligible to other radio spectrum users.

From the terms and conditions spelt out by OFCOM (pdf), the UK communications regulator.
Alternately, in the license guidelines:

1(4) The Licensee shall address Messages only to other licensed amateurs or the stations of licensed amateurs and shall send only:
(a) Messages relating to technical investigations or remarks of a personal character; or
(b) Signals (not enciphered) which form part of, or relate to, the transmission of Messages.
Answer: If you are in the USA, check <code>§ 97.113 Prohibited transmissions</code> of the FCC rules.
Specifically,

(4) Music using a phone emission except as specifically provided
  elsewhere in this section; communications intended to facilitate a
  criminal act; messages encoded for the purpose of obscuring their
  meaning, except as otherwise provided herein; obscene or indecent
  words or language; or false or deceptive messages, signals or
  identification.

As it stands now, encryption is prohibited regardless of your frequency.
Comment: OP appears to be in the UK.
Answer: It is prohibited in the US, with one exception. One is allowed to encrypt commands to an amateur satellite (Send from the ground to the satellite). Aside from that, encryption is prohibited.
Answer: Encryption on amateur radio is prohibited in most countries. There are some exceptions, in some countries, and for some specific use cases. You'll need to consult your local rules.
Some countries (Australia being an example) allow encryption in emergency communications and relevant training activities.
Some countries (US, for example) allow encryption for transmitting control commands to satellites, so that unauthorized stations can be prevented from causing harm to the satellite.
Some protocols used in digital networking (IPSEC, SSL/TLS) allow you to disable traffic encryption (using a "none" cipher), but still use cryptographic algorithms such as HMAC to do strong authentication and tampering prevention. Doing that does not conceal the contents of the traffic, so it's allowed, and sufficient for many use cases such as remote commands to satellites, or other restricted-access services.
Answer: Don N2IRZ wrote an article in CQ Magazine's August 2006 edition which made the case that data encryption is legal when it is used for the purpose of preventing unauthorized access. The context he's referring to is when using modified commercial WiFi routers which have channels that overlap with the amateur band (e.g. HSMM-Mesh/Broadband-Hamnet) and preventing part 15 users from joining part 97 mesh networks through the use of encrypted passwords such as WPA/WEP.
I'm not sure if his logic has held up in light of the recent FCC dismissal of a rulemaking petition to provide an exception for encryption for during disaster/public service operations, but it is an interesting read.
Comment: The FCC rightly dismissed that petition because the arguments made in support of it had no legal foundation whatsoever, as HIPAA does not apply to ham radio operators providing emergency communications support. In fact HIPAA does not apply to anyone when compliance interferes with rendering life-saving aid (for example when a patient is unable to give consent and the rules of implied consent apply). That petition was simply an attempt by whackers at an end run around the rules so they could play cop with their batwing p.25 radios.
Answer: In India, the Indian Wireless Telegraph Act (Amateur Service) rules mandate the operator transmit in plain language. Unfortunately I'm unable to locate a copy on the WPC web-site; hence a link to a copy by a fellow ham OM vu2mue.
Defining the conduct of an Amateur Station in Annexure I - Section II.1.b

(b) Transmissions shall be made in plain language and limited to messages of a technical nature relating to tests and to remarks of personal character (excluding business affairs or transactions) in which the licensee, or the person with whom he is in communication, are directly concerned and for which, by reason of their unimportance, recourse to the public telecommunication service is not justified.
Comment: Why the down-vote?
Comment: I didn't downvote this, but it would help if you included a link to the specific legislation and quoted it so that your claim can be verified.
Answer: I am going to repeat the answer I just put on a similar question.
Secure communication over Amateur-band HSMM / 802.11 in the United States
QUOTE:
If you want to do this kind of stuff in the USA, hiding and such, please stay off our ham bands.  These bands are reserved for those of us who have been properly licensed and follow the rules.
We don't need any headlines like "HAM RADIO OPERATOR ARRESTED FOR PASSING SECRET MESSAGES"
Comment: Sorry, but -1. The answer appears to be opinion based ("please stay off our ham bands", "we don't need any headlines"), doesn't quote any sources for whether or not it's actually allowed, and recommends using arbitrary bands between police channels (which is likely not just illegal, but also potentially disruptive to emergency services.)
Comment: The police band thing was just tongue-in-cheek.   But the "stay off our ham bands. These bands are reserved for those of us who have been properly licensed and follow the rules." is not just a personal opinion.  It is the law.

Encrypted traffic and amateur radio


Is the "Young Driver Surcharge" fee the same for all car rental companies in the UK?

Question: I am a 21 year old with almost 2 year old driving license. I'm going to the UK, and want to rent a car for several days, however when I searched for a rental car, I saw that 35-40 GBP were added as "Young Driver Surcharge" for each day. My question is, does this additional fee change from one rental company to other, or can I find a rental company that charges less for the same thing?
Comment: [This discussion on FlyerTalk's UK Forum](http://www.flyertalk.com/forum/u-k-ireland/1587447-car-hire-u21s-waived-young-drivers-fee.html) has some information and suggestions, but no clear conclusion...
Answer: No, these fees may vary, as may the age range they are applied for. Note also these change significantly between countries (and in some cases even between locations within a country).
Some of the main supplier's conditions in the UK:

Supplier   MinAge   Fee   NoFeeAge

Alamo        22     £27^     25
Avis         21     £45      25
Budget       23     £39"     25
Enterprise   25      ?       25°
Europcar     22     £31      25
Hertz        23     £31"     25
National     22     £27^     25
Sixt         21     £36      25*
Thrifty      21     £25"     25

"incl. tax - suppliers with no note may or may not be incl. tax
^excl. tax - suppliers with no note may or may not be incl. tax
°Enterprise is not very clear; the selection form allows selecting age 18-24, but the terms say minimum age 25. Also the selection form returns an error saying 'some locations' may have age restrictions on all UK locations I have checked.
*Sixt is not consistent in what is says on it's site. The Rental Guide says ages 21-23 will face the charge and mentions neither car classes on the amount payable, the Rental Information says all drivers below 25 pay £36 and lists a range of car classes which basically comprises all available for hire below the age of 25.
One additional note for the northern regions: Arnold Clark rents cars without young driver surcharges in some locations - T&C.
Here are links to the relevant pages of the mentioned suppliers - with the exception of Avis which does not allow direct linking to any useful page it seems: Alamo
Budget, Europcar, Hertz, National, Thrifty
Comment: Old answer, I know. But in the past I've managed to hire from Sixt (at age 24) without paying the fee.


What does it mean when a game is labeled "Games for Windows"?

Question: Several games these days have a banner across the top of the box that reads Games for Windows.  What does this mean?  Should I care?
Answer: The "Games for Windows" scheme is Microsoft's attempt at regulating the PC games market in a similar fashion to how the console games markets currently are. Any game carrying the banner has to meet many technical specifications, including compatibility with the latest versions of Windows available at the time of release, and it has to have undergone and passed a rigorous testing process. See here for Microsoft's official description.
Answer: Additionally, some games are labeled "Games for Windows LIVE" and those games allow you to connect to the Windows Live service (which most people associate with Xbox Live, it's the same thing). Games labeled as such allow you to get achievements worth points towards your gamerscore, see your friends online and chat with them, etc. Some people use this as a method to pad their gamerscore with points, as you can, for example, buy Fallout 3 for both Xbox and GFWL and get twice the point credit for playing the same game.
Answer: It's a brand owned by Microsoft. Those game are certified by Microsoft to work on Windows (introduced with Vista in 2006)
http://en.wikipedia.org/wiki/Games_for_Windows
Answer: Apparently there are also port forwarding requirements for multiplayer play under this system.  This can be a deal-breaker if you're trying to play it behind the same NAT'ed firewall.


Why does an octave on a piano have the divisions of 8 white keys and 5 black keys?

Question: An octave corresponds to a doubling or halving of the frequency. Each octave on a piano and in classical music score is broken downs into 8 white keys and 5 black keys. Is there a physics explanation for that division?
Comment: The assignment of notes as white or black keys has nothing to do with physics or acoustics. In the equal temperament tuning system typically used for e.g. pianos, each note has a frequency a factor of $\sqrt[12]{2}$ greater than the next lower note, regardless of whether it's black or white.
Answer: Keith Thompson's answer, while good, makes it seem that there is some intrinsic difference between the black keys and white keys, and that only the white keys approximate integer harmonies. This is not really true. The white keys are just the C major scale, and the most important purpose the black-key/white-key distinction serves is to make it easy to see where your fingers are, because the underlying structure is too symmetric, and without a pattern, it is easy to get lost.
The integer ratio stuff is mostly for the three notes CFG, which are adjacent on the circle of fifths. These tones do have an integer ratio, with no qualification. There is a very weak integer ratio on E:C of 5:4, but this ratio is

badly approximated in the 12 tone system
unusable by the ear for purposes of extrapolation of a fundamental frequency, because the putative fundamental frequency is 2 octaves away
Has an exact counterpart in the ratio of C to G#, which is 4:5. But G# is a black key.

All the 5:4 tone (major third) does, when played with C, regarding the percieved C tone is modify the timbre somewhat. similarly, C modifies the timbre of the G# tone in the same way. The lower tone sets the fundamental frequency you tend to hear, but if the higher tone is part of a melody, the ear will mostly separate it out.
The white key corresponding to B is maximally discordant with C, has the largest denominator ratio to C of all the keys in a rational approximation, while the black key corresponding to B-flat/A-sharp is as about as harmonious with C as the white key corresponding to D. So even relative to C, white-key black-key does not indicate special harmoniousness.
The key for B-flat/A-sharp is omitted from the major scale by a scale convention, which is fixed by requiring good relative harmonies between different tones in the scale overall, not just relative to C. You also require that you contain the major chords of the F and G in the C scale, and that fixes the major scale. The C minor scale is more rationally harmonious relative to C than the major scale (it is basically the major scale going down, so the ratios are the reciprocals of the major scale frequencies, except for that the most discordant note is omitted and replaced with a less discordant one), and it includes A-sharp/B-flat. B is included in the major scale because it is a leading-tone, you traditionally use it only to signify a transition to C, and, more significantly because it is the fifth of the major third, and the major third of the fifth.
Although this stuff is trivial, it looks complicated in the usual language musicians use, because this is full of ponderous historical cruft.
Comment: To be musically pedantic: surely you mean that the E-to-C ratio has an exact counterpart in C-to-*A flat*!
Comment: G-sharp and A-flat are the same on the piano, so I don't see your point. I _never_ make a distinction between G-sharp and A-flat, because it doesn't exist on the piano, my ear does not hear it, it is so small it is smaller than the natural detuning on stringed instruments, and it is of the same order as the integer-ratio errors in the standard 12 tone scale. The music-theorist's distinction between the two is absurd, and pointlessly obscures the simple Z/12 structure of the tones. I actually wrote a pages-long answer, which was a diatribe on music theory, but I erased it at the last minute.
Answer: Modern keyboards are tuned with each of the 12 half-step intervals between one octave and the next being equal, so a half-step is a ratio of the 12th root of 2 (about 1.059), and a whole-step is a ratio of the 6th root of 2 (about 1.122).
But the ratios that "sound nice" musically tend to be ratios of small integers.  2:1 is an octave, of course.  3:2 is a "fifth".  In older tuning systems, a fifth was exactly a 3:2 ratio (which made transposing from one key to another difficult).  The modern "equal temperament" system approximates this to 7 half-steps, a ratio of about 1.498.  We've traded off those exact small integer ratios for consistency.
The ratios represented by the white keys on a piano are generally chosen as the ones that are close to small integer ratios.  A 6-half-step interval (C natural to F sharp) is a ratio of sqrt(2), about 1.414, which sounds dissonant.
See here for more details -- or find and read an entire book on musical theory.
Answer: There is no easy answer for this. It happens to be a good arrangement for many reasons. Several factors would have contributed to the original design.
Western music is based on the diatonic scale.
C D E F G A B is the diatonic scale on C.
Musical staves, created by Gregorian monks to record their plainchants before the existence of keyboards, and still in use in today's notation, represented this diatonic scale. Other notes and scales to be achieved by kludging this notation with accidentals and key signatures.
So notationally, and hence conceptually, everything is seen in terms of a distorted diatonic C scale.
The most early and primitive musical instruments played diatonic scales.
Hence there is some logic behind the decision to start the piano keyboard off with a diatonic scale in C and arrange the enharmonic (out of scale) notes around this.
It is in some way a mirroring of the pre-existing notation.
The layout of the piano keyboard was finalised before 12-TET (equal temperament where the ratio of each note to the next is the same, i.e. 12th root of 2)
Before 12-TET, the instrument would be tuned perfectly to C, but the further the tonal centre moves, the more out of tune it will sound. Instruments would have to be tuned for individual pieces. Some instruments you can use multiple rows of keys. It was a mess. But 12-TET cannot use as an argument for the existence of this layout -- it came much later!
This question should be migrated to the music stack exchange site. It will accrue misinformation on a physics site. I can see from the existing answers that this is already the case.