Why is it even possible to forge sender header in e-mail?

Question: With so many popular e-mail providers forcing users to log on using their SMTP servers, why is it still possible to forge "From: " header in e-mails? What prevents users from simply discarding the e-mails in which the source domain of the sender doesn't match the domain of SMTP server?
Comment: For almost precisely the same reason that I could, hypothetically, write your return address on a threatening letter to a government official.
Answer:
tl;dr

It's very easy to spoof a domain even with SPF controls enabled.

The solution is to use DKIM + DMARC, or SPF + DMARC

The email client is responsible for telling you if the message passes DMARC Display From verification

The email protocol allows for legitimate spoofing using Resent-* headers and Sender headers.  The email client (MUA) should display this exception whenever it exists.

There are a few misconceptions about SPF, namely:

SPF does not prevent email spoofing.
SPF alone doesn't affect, influence or, control the RFC 2822 Display From.
By default, the usefulness of SPF is to prevent backscatter issues and very simple spoofing scenarios.

Microsoft attempted to solve this issue with SenderID, (making SPF apply to the Display From address) but it was too complicated and didn't really solve the whole problem.

Some background
First know that there are two "from" addresses and two "to" addresses in every SMTP message.  One is known as the RFC2821 Envelope, the other is the RFC2822 Message.  They serve different purposes
The Envelope:  (RFC2821)

The envelope is metadata that doesn't appear in the SMTP header.  It disappears when the message goes to the next MTA.

The RCPT From: is where the NDRs will go.  If a message is coming from Postmaster or a remailer service this is usually <> or firstname.lastname@example.com.  It's interesting to see that salesforce uses this similar to constantContact as a key in a database like firstname.lastname@example.com to see if the message bounced.

The RCPT TO: is who the message is actually being sent to.  It is used for "to" and "bcc" users alike.  This doesn't usually affect the "display of addresses" in the mail client, but there are occasions where MTAs will display this field (if the RFC2822 headers are corrupt).

The Message (RFC2822)

The message portion begins when the data command is issued.

This information includes the SMTP headers you're familiar with, the message, and its attachments.  Imagine all this data being copied and pasted from each MTA to the next, in succession until the message reaches the inbox.

It is customary for each MTA to prefix the above mentioned copy and paste with information about the MTA (source IP, destination IP, etc).  It also pastes the SPF check details.

This is the Display From is placed. This is important.  Spoofers are able to modify this.

The Mail From: in the envelope is discarded and usually placed here as the return-path: address for NDRs

So how do we prevent people from modifying the Display From?  Well DMARC redefines a second meaning for the SPF record.  It recognizes that there is a difference between the Envelope From and the Display From, and that there are legitimate reasons for them to not match.  Since SPF was originally defined to only care about Envelope From, if the Display From is different, DMARC will require a second DNS check to see if the message is allowed from that IP address.
To allow for forwarding scenarios, DMARC also allows the Display From to be cryptographically signed by DKIM, and if any unauthorized spammer or phisher were to attempt to assume that identity, the encryption would fail.
What is DKIM?  DKIM is lightweight cryptographic technology that signs the data residing in the message.  If you ever received a message from Gmail, Yahoo, or AOL then your messages were DKIM signed.  Point being is that no one will ever know youre using DKIM encryption and signing unless you look in the headers.  It's transparent.
DKIM can usually survive being forwarded, and transfered to different MTAs.  Something that SPF can't do.  Email administrators can use this to our advantage to prevent spoofing.

The problem lies with the SPF only checking the RFC2821 envelope, and not the Display From.  Since most people care about the Display From shown in an email message, and not the return path NDR, we need a solution to protect and secure this piece.
This is where DMARC comes in. DMARC allows you to use a combination of a modified SPF check or DKIM to verify the Display From.    DKIM allows you to cryptographically sign the RFC2822 Display From whenever the SPF doesn't match the Display From (which happens frequently).

Your questions

Why is it still possible to forge "From: " header in e-mails?

Some server administrators haven't implemented the latest technologies to prevent this sort of thing from happening.  One of the major things preventing adoption of these technologies is "email forwarding services" such as a mailing list software, auto-forwarders, or school alumni remailer (.forwarder).  Namely:

Either SPF or DKIM isn't configured.

A DMARC policy isn't set up.

The email client isn't displaying the verification results of the Display From and the Resent-* or Sender field.

What prevents users from simply discarding the e-mails in which the source domain of the sender doesn't match the domain of SMTP server?

What doesn't match: the envelope or the body?  Well according to email standards the envelope shouldn't match if it's going through a remailer.  In that case we need to DKIM sign the Display From and make sure the MUA verifies this.
Finally, the MUA (email client) needs to show if the sender is DMARC verified, and if someone is trying to override that with a Sender or Resent-From header.
Answer:
What prevents users from simply discarding the e-mails in which the source domain of the sender doesn't match the domain of SMTP server?

Nothing. They are allowed to, and many use this to filter out spam.
Like a lot of technologies with security shortcomings, e-mail wasn't designed with security and authentication in mind. The purpose of the "from" field was more-or-less the same as for a traditional snail-mail envelope. To make e-mail usable in the light of 21st century needs and abuses, we have had to added adjuncts. Specifically, SPF addresses the first part of your question:

With so many popular e-mail providers forcing users to log on using their SMTP servers, why is it still possible to forge "From: " header in e-mails?

The solution is to verify the header/IP at receiving time. While this doesn't technically prevent the actual forging of the header, it does make forged headers less useful.
Answer: There is already partial protection against that: https://en.wikipedia.org/wiki/Sender_Policy_Framework
All popular email providers use it.
But they handle SPF failure differently, some mail providers will totally discard messages based on that check, and some providers will just put it in spam folder.
Anyone can create his own email server and try to send as anyone.
You can check your gmail address (if you have one) and open the header of any email, and you will see the result of the SPF check on the top:
spf=pass (google.com: domain of *****@*****.com designates 174.**.**.** as permitted sender) smtp.mail=*****@*****.com;
Comment: -1 this is a misconception that SPF "fixes" this problem.  SPF is limited in usefulness and reliability.  More needs to be done.
Answer:
[...] why is it still possible to forge "From: " header in e-mails?

SMTP is a protocol designed back when you could likely name every machine on the Internet, and running a machine that provided mail was a relatively big deal, undertaken by large organisations and very dedicated hobbiests. It doesn't have any built-in protection or security against bad actors and trusts pretty much whatever you tell it.
There are also a whole host of legitimate reasons you may want your 'From:' header to be different to your domain - perhaps your mail server is shared with many other domains (such as a web/mail hosting company), in which case your reverse (PTR) record and your forward (A/MX) record will necessarily differ.
However, given that the majority of users, in a majority of cases will be using a mail service that matches their mail domain; we can apply some logic around SMTP. This leads on to your next question:

What prevents users from simply discarding the e-mails in which the source domain of the sender doesn't match the domain of SMTP server?

The answer here is nothing, and people do.
There are a whole host of methods for identifying spam such as:

As you suggest - checking that the sender domain matches the sending domain (either via DNS, or by connecting to the sender and checking)
Checking the SPF records for the sending domain for 'allowed' hosts
Bayesian spam filtering / Markovian Discrimination
Blacklists

Classification problems like identifying spam/non-spam are major areas of study. It is, unfortunately, not just as simple as dropping mail that doesn't come from where you'd expect (witness the huge number of spam messages coming from gmail accounts to gmail accounts), and applying that rule is likely to hit a huge number of snags (in the case where your mail server is in some way shared); you can however include that in your analysis of the message and trust it less, and once you get past some level of certainty, just drop it.
Email will likely always have these sorts of abuse issues as it's inehently a system for allowing people to send and receive messages to anyone with as little friction as possible. By it's nature, it allows people you don't know to send you messages you weren't expecting, and, just like with the regular mail system, this is both a good and bad thing.


Which microphone to choose for normal recording

Question: I'm confused between 2 low budget recording microphones. One has a sensitivity of 2mV/Pa and the other one has that of 2.5mV/Pa. Which one should be chosen? How does sensitivity affect sound quality?
Comment: 2 vs 2,5 mv/PA is a difference of 1dB, less than the ear can hear.
Answer: That difference in sensitivity isn't really going to make a difference in recording quality. What about other factors, such as the frequency response, frequency range, whether the mic is directional, etc. All these are of more importance depending on what sort of recordings are envisaged. I understand that this is off axis to the direct question, although those sensitivities mentioned seem to be possibly the smallest consideration when choosing a mic.
Many other factors are of more importance, including the kind of mic chosen - ribbon, dynamic, condenser, etc., not forgetting the rest of the recording chain, making a difference of 0.5mV/Pa not so important.
And it's unlikely you'll find two mics with every other spec identical, except that sensitivity.
Answer: If your preamps are your limiting quality factor, higher sensitivity will result in better recordings.  If your microphones are your limiting factor, the lowest equivalent noise level will make the better recordings.
All other things being equal, which they never are.  So a difference like that is rarely going to be decisive.
Also, low budget microphones (and I mean low budget) tend to fantasize their specs anyway because if their makers had the required measurement equipment and location, they'd also have what it takes to develop non-low-budget microphones.  And they won't outsource the measurement since the results would make them sell worse than if they just invented values.
Answer: Every piece of equipment in a recording set-up affects the final product, that said, you can often achieve good results with mediocre equipment if you're willing to put in the time to find out what works. Trial and error are often part of the creative process, but it is usually time consuming. specifications don't mean that much if your focus is not on design and engineering. how it sounds when used in conjunction with the rest of the gear is usually much more important. Ask to try the mics in question for a short time and then purchase the mics that suit you best.


Cross-Validation in plain english?

Question: How would you describe cross-validation to someone without a data analysis background?
Comment: This question is to help with any confusion over the site name proposal: http://meta.stats.stackexchange.com/questions/21/what-should-our-site-be-called-what-should-our-domain-name-be/53#53.
Answer: Consider the following situation:

I want to catch the subway to go to my office. My plan is to take my car, park at the subway and then take the train to go to my office. My goal is to catch the train at 8.15 am every day so that I can reach my office on time. I need to decide the following: (a) the time at which I need to leave from my home and (b) the route I will take to drive to the station.

In the above example, I have two parameters (i.e., time of departure from home and route to take to the station) and I need to choose these parameters such that I reach the station by 8.15 am.
In order to solve the above problem I may try out different sets of 'parameters' (i.e., different combination of times of departure and route) on Mondays, Wednesdays, and Fridays, to see which combination is the 'best' one. The idea is that once I have identified the best combination I can use it every day so that I achieve my objective.
Problem of Overfitting
The problem with the above approach is that I may overfit which essentially means that the best combination I identify may in some sense may be unique to Mon, Wed and Fridays and that combination may not work for Tue and Thu. Overfitting may happen if in my search for the best combination of times and routes I exploit some aspect of the traffic situation on Mon/Wed/Fri which does not occur on Tue and Thu.
One Solution to Overfitting: Cross-Validation
Cross-validation is one solution to overfitting. The idea is that once we have identified our best combination of parameters (in our case time and route) we test the performance of that set of parameters in a different context. Therefore, we may want to test on Tue and Thu as well to ensure that our choices work for those days as well.
Extending the analogy to statistics
In statistics, we have a similar issue. We often use a limited set of data to estimate the unknown parameters we do not know. If we overfit then our parameter estimates will work very well for the existing data but not as well for when we use them in another context. Thus, cross-validation helps in avoiding the above issue of overfitting by proving us some reassurance that the parameter estimates are not unique to the data we used to estimate them.
Of course, cross validation is not perfect. Going back to our example of the subway, it can happen that even after cross-validation, our best choice of parameters may not work one month down the line because of various issues (e.g., construction, traffic volume changes over time etc).
Comment: Technically, this is holdout validation but one can imagine extending the subway example to a cross-validation context. If it helps I will re-write the example and the rest of the text to be specific to cross-validation.
Comment: I think this answer would be improved by adding the concept of folds, which is the key to how CV is different from holdout testing. In the example (using abbreviation M for Monday, T for Tuesday,  ..., R for Thursday, ...): So you look at TWRF for the best combination and see how that works on M, then MWRF and see how it works on T, etc. So each day is used as a part of the problem four times and as the check to the problem once, but never as the problem and the check in the same round.
Comment: @srikant..the word overfitting as a word suggests me that something is "overly" done meaning ..more than required..so whats overly done ? Is it no of variables ? I am sorry I have been hearing the term overfitting many times and would take this oppurtunity to cleare this with you.
Answer: I think that this is best described with the following picture (in this case showing k-fold cross-validation):

Cross-validation is a technique used to protect against overfitting in a predictive model, particularly in a case where the amount of data may be limited.  In cross-validation, you make a fixed number of folds (or partitions) of the data, run the analysis on each fold, and then average the overall error estimate.
Comment: @drknexus: That's fair, but I mention that it's k-fold and I wanted to provide a visualization of the process to help explain it.
Comment: It seems given discussions elsewhere on this site that k-fold cross validation is just one type of cross validation and describing it does not do the general job of describing what cross validation is.
Comment: Quick clarification: is it the case that, nfold=4 means 25% for test set; nfold=5 means 20% for test set; nfold=10 means 10% for test set, and so forth: nfold = n means 100/n percent goes into the test set?
Answer: "Avoid learning your training data by heart by making sure the trained model performs well on independent data."
Comment: This is motivation for cv, rather than a description of cv itself.
Answer: Let's say you investigate some process; you've gathered some data describing it and you have build a model (either statistical or ML, doesn't matter). But now, how to judge if it is ok? Probably it fits suspiciously good to the data it was build on, so no-one will believe that your model is so splendid that you think.
First idea is to separate a subset of your data and use it to test the model build by your method on the rest of data. Now the result is definitely overfitting-free, nevertheless (especially for small sets) you could have been (un)lucky and draw (less)more simpler cases to test, making it (harder)easier to predict... Also your accuracy/error/goodness estimate is useless for model comparison/optimization, since you probably know nothing about its distribution.
When in doubt, use brute force, so just replicate the above process, gather few estimates of accuracy/error/goodness and average them -- and so you obtain cross validation. Among better estimate you will also get a histogram, so you will be able to approximate distribution or perform some non-parametric tests.
And this is it; the details of test-train splitting are the reason for different CV types, still except of rare cases and small strength differences they are rather equivalent. Indeed it is a huge advantage, because it makes it a bulletproof-fair method; it is very hard to cheat it.
Answer: Since you don't have access to the test data at the time of training, and you want your model to do well on the unseen test data, you "pretend" that you have access to some test data by repeatedly subsampling a small part of your training data, hold out this set while training the model, and then treating the held out set as a proxy to the test data (and choose model parameters that give best performance on the held out data). You hope that by randomly sampling various subsets from the training data, you might make them look like the test data (in the average behavior sense), and therefore the learned model parameters will be good for the test data as well (i.e., your model generalizes well for unseen data).

Cross-Validation in plain english?


What is the best way to record acoustic piano and vocals from home?

Question: I am staying in a rented house which I cannot sound-proof. I have an acoustic upright piano which I cannot carry to a studio. The noise levels around are average, no heavy traffic, but passing car horns, animals, children playing etc get heard at times.
I would like to know, what is the best way to record piano with vocals in this scenario? I am happy with doing live takes with no overdubbing for a start. If I have to choose between a high end dynamic mic and a not-so-high-end condenser mic, what would be better?
Comment: Hey man what is the status of your recording project?
Answer: Actually you can do soundproofing without damaging the house. Using acoustic panels (expensive but provides the best result) works, however some well placed blankets using string and 3M adhesive hooks in a carpeted room can vastly change the sound of the recording because of reduced reverberation.
Picking a recording time that has the least amount of noise pollution (midnight?) may also help with the external audio source problem.
I would recommend recording vocals and piano separately to achieve the best results. It is difficult if nigh on impossible to properly mic a piano with one mic; let alone a piano and vocalist.

A condenser mic will meet your needs best because even good dynamic mic's can struggle to capture the higher frequencies produced by a piano. Even mid level mics can produce great results if used properly.
The caveat though is placement. You will have to experiment with
placement to find what sounds best. Every audio pro will tell you
that if you have a lousy sound being recorded, fixing it will be
difficult    at best later.
A condenser can also be used for vocals. Most studio mic's are condensers. It is possible, though unlikely, that the condenser you have in mind is inadequate for recording both audio sources well (provided both are recorded separately, and proper mic placement is used.

This is a great (fairly technical) piece on how to mic a piano.
A less technical piece on finding the best mic position for an instrument.
Answer: To answer your first question there needs to be more detail. Is the piano an upright piano or grand? Do you plan to record only live takes or will you be overdubbing?  In answer to your second question, generally condenser mics are a better choice on piano, but again this could use more clarification in regards to specific mics that you're trying to decide between.
Comment: Question updated.


Removing enchantments from hexproof creatures

Question: I have some hexproof creatures in my deck and several enchantments. What I wish to know that if I put an enchantment like "Trollhide" on my hexproof creature like "Sacred Wolf" can an opponent remove it from my Sacred Wolf with an enchantment-removing spell, or my enchantment becomes hexproof too?
Comment: NOTE - Of course, cards like 'Paraselene' - Which 'destroy all enchantments' - are especially useful if your opponent has taken this into consideration, and is using a card that makes ALL enchantments hexproof. Cards like 'Sleep' would also take effect, as they're not targetting the creature (admittedly, it won't destroy the creature or remove enchantments, but it buys you time to - hopefully - draw a card that can).
Answer: The enchantment doesn't become hexproof.  It is only the creature that cannot be targeted by [an opponent's] spells and abilities.
So supposing that you have a spell that says "destroy target enchantment".  This spell can remove an enchantment that's on a hexproof creature.
But suppose that you had an (imaginary) spell that says "exile all Auras on target creature".  This would not have any effect on your Trollhide-toting Sacred Wolf, because it needs to target the creature, not the enchantments, and this time this is illegal.
EDIT: Since there's a bit of a mania for quoting the Comprehensive Rules at the moment, here's the section on hexproof:

702.11b "Hexproof" on a permanent means "This permanent can't be the
  target of spells or abilities your opponents control."

That's all it means.  The hexproof doesn't confer any immunity from targeting on anything other than the permanent that has hexproof.
Comment: Mania?!? You callin' me crazy? I take great pride in quoting the Comprehensive Rules! Answer with references and authoritah!
Comment: _But suppose that you had an (imaginary) spell that says "exile all Auras on target creature"._ -- There's no "exile all auras on target creature," but Strip Bare (Shadowmoor) destroys all auras and equipment attached to target creature.
Comment: What is this comment?


sudo logs date with user's locale, apparently. How do I make it use "C" locale?

Question: I have sudo set to log to /var/log/sudo.log.  I've noticed that when the locale was set to "de_DE.UTF-8", it logged a localized date ("Mär" for "März") instead of "C" locale ("Mar" for "March").
How do I make it log the date independent of the user's locale?  Where the **** is that documented, anyway?
Or am I halluzinating?  (Could be, since I've got a major cold... ;-))
Answer: Try creating an alias:
<code>alias sudo='LANG=C sudo LANG='
</code>


Luggage locker at Warsaw Central Railway Station

Question: I am wondering if there are luggage lockers at Warsaw central railway station (I highly suspect there are) and if there are, do they have different size lockers? and I'd like to know the prices. Couldn't find exact information via google.
Answer: The Man in Seat 61 says that there is both an unmanned 24-hour locker service, as well as a manned left-luggage service at Warsaw Central station. Quoting from the Man himself:

Warsaw:  Warsaw Centralna has luggage lockers in the passageway at the top of the steps to the platforms, around 9 zlotys (£2) per locker per 24 hours.  There's a staffed left luggage office off the same passageway, 10 zlotys per item per 24 hours, open 07:00-18:20, 19:00-06:20 with breaks 10:00-10:15 & 14:00-14:30.
Answer: Various sizes at 12,14,16 Złoty for 24 hours, as at Feb 2019. Medium rucksack to large enough for 2 decent size suitcases.
Answer: There are, unmanaged ones can be found at the North-East corner, don't remember exactly but most likely at (-1) level. As far as I remember there are quite spacious lockers.


What should I look for in weather reports in order to pick a day for glider flying?

Question: I understand weather can change unexpectedly, and local sky condition (e.g. cloud types) can't be predicted, but if I want to fly glider at a specific location, say, some time next week, and use weather forecast to pick the best possible day, what should I look for? e.g. "Cloudy" vs. "partly cloudy" vs. "overcast" vs. "sunny", is one preferable to another? (I wish the forecast would say something like "Cumulus clouds abound")
Comment: What kind of glider flying do you want to do? Soaring? Long distance? Mountain wave?
Comment: This question can not be answered. There are several types of glider flying such as upsloap and thermal which have different weather requirements. The geography may also play a part such as upslope soaring.
Comment: Just short glider flying lessons in/near mountains/valleys.
Answer: For thermal soaring, which is the majority of the time in the sport in North America, the best soaring days are usually the day or two or three after the passage of a cold front with high pressure behind it, where light to moderate winds are forecast.  You want relatively unstable air without any inversions, no mid to high level clouds, and low humidity but preferably enough to form cumulus clouds to mark the thermal tops (if the air is really dry you have no clouds at all and have to troll randomly looking for lift, or look for thermaling birds, or look for other gliders that have found lift). In other words, it's those clear sunny days after a high moves through, the temperature cools off, and you get those nice puffy widely separated cumulus clouds and light to moderate winds.
If a front ahead of high pressure has a strong pressure gradient behind it, it's likely that the winds the next day will be strong and this is bad because it tends to break up the thermals.  In that case I would plan to go the day or two after as the high moves in and the winds die off.
There are a lot of other factors, like the ground moisture content (wet ground sinks heat and inhibits thermal formation), but as a way to try to judge the best likelihood of good soaring conditions, the 2-3 days following passage of a cold front rule is the most reliable.
If you're not much at interpreting weather maps and can only go by the public forecast, and have to pick a day in advance, try to pick one of the first days following the day with storms and a temperature drop in the forecast due to a cold front, where it shows sunny or "partly cloudy" (which will usually be be desirable convective cumulus) for a few days after, and avoid really windy days which if it happens is typically the first day after frontal passage.
Exceptions to this are desert areas which have sunshine and good convective conditions for thermals pretty much all the time, and places like Florida where during any kind of sunny weather there is always convection (there is a localized thunderstorm somewhere in the state just about every day in summer).
Comment: Thanks. You have precisely addressed my question.
Answer: It very much depends upon what type of flying you normally do.
I can only really comment on what I do, you will have to adjust for your own circumstances.
At my local glider field we mostly fly on ridge lift as we have a very wedge-shaped ridge right next to the airfield, it has a very steep southwest face that tapers away towards the North. We also have a small range of hills to the SW of the field that faces NW that gives ridge lift. This means that I predominantly look for wind direction and strength, wind from the West gives good lift but from the East the wind just makes massive sink. We had a wind from the East for a couple month earlier this year and so all we managed was circuits.
The second most important lift for me is wave. I live in Scotland is quite small and which has mountains all down the western side of the country. I keep an eye out for wind coming off the sea and striking the mountains as this causes wave which ripples all across the country.
Cloud is obvious. I look for a decent cloudbase, high enough to allow me to fly without entering the cloud. Also I check for rain forecast and avoid rainy days. Cloud cover is less of an issue to me as I live in a hilly country where thermalling is less important than hill lift as there is always a hill nearby.
The best advice I can give is to talk to your chief flying instructor at the club and get advice specific to your airfield. I'm guessing that from the question you are a beginner flyer and so your flights will likely be around your airfield. Your CFI will know the area intimately and can tell you just what to look for and what websites to go to for forecasts and how to interpret them.


How do I pass value to list event receiver?

Question: I have a document library that have a column named "Region", after some user uploads a doc to the library, I want to update this column based on this user's region property. for example, if this user's region property is "Canada", once he/she uploads the doc, the column "Region" should be marked as "Canada".
  So far, I can make the event firing, but I have no idea how to pass user's region value to the event handler.
   Please help. Thank you.
Answer: You do not "pass" data to an event receiver.
In your scenario, the user's region must be stored somewhere. (The most likely place is in their user profile.) You can access the user whose action caused the event to occur thru the "UserLoginName" property of the event properties. Use this value to query the profile (or some other storage medium) for the region of the user.
Answer: You can get the region information based on current user information from the properties passed into the event method:
properties.OpenWeb().CurrentUser.RegionalSettings
Actually, you can get almost anything you need from properties.


Xcode hook up with Unity

Question: Hi i am new bee in Unity but i have 1 year experience in Xcode, I am doing an app in Unity for iPhone but getting bit confuse on how can i hook-up Xcode with Unity, I want to Facebook sharing, Twitter Sharing and also iOS native Email sharing(Using Mail Composer) in Unity but i don't get any help ful solution to do task in Unity, I only get Plugins which i need to Purchase first. So i want to do this task in Xcode it reduce and time and money and rest of work on Unity so is this possible that we can Communicate between Xcode and Unity? If Possible then kindly share some knowledge and links with me so that i can do this task ASAP.
Thanks in Advance.
Answer: You can start write your own plugin to complete the communication between Unity3D and iOS.
From iOS to Unity, You can just use UnitySendMessage, which is enough in most of time. You can also try to use a event and delegate in Unity Script to handle more complex situation.
From Unity to iOS, you need to implement plugin yourself. First of all, use a .cs file to declare the external method. And then implement the native code in a .mm file in Xcode and "extern C" them to the Unity. Then you can call the .cs method and get a native function called. You need a Unity Pro license to use the plugin feature.
For UnitySendMessage and Unity plugin, visit Unity Doc-Building Plugins for iOS. You can find an example in the doc called Bonjour Browser Sample. It is a very good starting point for you. If you have 1 year experience with Xcode, I think it will be easy for you.
For use delegate and event in Unity, visit Prime31's Unity Tip video.
Comment: Thanks, its already done with the help of Doc-Building Plugins for iOS.
Answer: Check out Niklas's free unity iOS plugin.
http://forum.unity3d.com/threads/122681-Free-facebook-Plugin-for-Unity-iOS
It doesn't work out of the box anymore, but with a few changes and updates you can get it working.
If you already have xCode experience then hopefully the extra work should be trivial since the Facebook SDK docs are pretty good.

Xcode hook up with Unity


Does Windows 7 have built-in support for creating & mounting disk images?

Question: Does Windows 7 have any built-in tools (GUI/command-line) for creating and mounting disk images (similar to Disk Utility/hdiutil on Mac OS X)? I did a quick search in the Windows Help for "disk image", which gave me info about how to create an image of the entire system and how to burn images to optical discs; but the tools involved seem to be limited to those two particular usage scenarios. Is there any command-line only support, or do I need to turn to third party tools?
Answer: it depends on the sort of image.
Windows 7 has VHD support built in - you can use diskpart to create a disk image
creating a VHD

diskpart create vdisk
file=c:\virtual\win7.vhd type=fixed
maximum=16000

This creates a 16 gb vhd called win7.vhd
You can mount it

diskpart select vdisk
file=d:\virtual\win7.vhd attach vdisk

via zdnet
You can create standard IMG files by other means and mount it with filedisk
if you want to mount other sorts of files, it depends - I believe there's vmware diskmount (may not work on newer versions of windows)
I have no idea what will mount a VDI
Answer: Virtual Clone Drive is another freeware app that's quite useful for mounting images of different formats. You can create multiple virtual drives too.
Answer: Windows 7 does not have a feature to create and mount disk images like ISO, IMG, BIN, etc. As you have found out after your search, Windows 7 only lets you burn images (yet not all types) to optical discs. You should use a 3rd party tool.
Answer: I use the freeware app MagicDisk on Windows 7 (64-bit) to mount ISOs - works very well.
For burning and making images, I use CDBurnerXP (works fine on WIn 7 too) - also free.


'exec' not working with private method Python

Question: I know that most of You stays for that exec shouldn't be used, but I have some problem.
Here is minimal example, which works:
class A:
    def __init__(self):
        exec('self.a = self.funct()')
    def funct(self):
        return 1
    def ret(self):
        return self.a
> obj = A()
> obj.ret()
1

But, when I do:
class A:
    def __init__(self):
        exec('self.a = self.__funct()')
    def __funct(self):
        return 1
    def ret(self):
        return self.a
> obj = A()
AttributeError: 'A' has no attribute '__funct'

Does anybody know why is that difference?
Comment: Note that `__` names are **class** private. That's not the same thing as privacy models in other languages.
Answer: __name names are class private; such names are prefixed, at compile time, with another underscore and the class name. The purpose is to protect the names from accidental clashes with names used in subclasses. These names are not meant to be private to outside callers.
Quoting the Reserved classes of identifiers section:

__*
  Class-private names. Names in this category, when used within the context of a class definition, are re-written to use a mangled form to help avoid name clashes between "private" attributes of base and derived classes.

and the Identifiers (Names) section:

Private name mangling: When an identifier that textually occurs in a class definition begins with two or more underscore characters and does not end in two or more underscores, it is considered a private name of that class. Private names are transformed to a longer form before code is generated for them. The transformation inserts the class name, with leading underscores removed and a single underscore inserted, in front of the name. For example, the identifier __spam occurring in a class named Ham will be transformed to _Ham__spam. This transformation is independent of the syntactical context in which the identifier is used.

What happens in your case is that exec() postpones compilation, effectively compiling that call in isolation. The class context is gone, so no mangling takes place.
As such, you need to apply the automatic prefixing manually:
exec('self.a = self._A__funct()')

If you are using Python 3, you could use the __class__ closure normally available for the super() function to access the class name the current method is defined for:
exec('self.a = self._{0.__name__}__funct()'.format(__class__))

Now, unless you actually plan for your class to be widely subclassed in third-party code that should not have to worry about accidentally clashing with internal implementation details, you should not be using double-underscore names at all. Stick with single-underscore names instead.
Answer: Python private methods are "disguised" under a different identifier than the one specified in the code, you can access them like _classname__privateAttribute.
Posting this to be specific:
class A:
    def __init__(self):
        exec('self.a = self._A__funct()')
    def __funct(self):
        print("Hello")
    def ret(self):
        return self.a

obj = A()

I put the print answer there to detect if it worked, and it did!


If I edit my answer, does the asker get a notification?

Question: ... if they don't, what's the right "protocol" to "let them know" that I've significantly improved the answer?
Comment: If you really significantly changed your answer, and there was no other answer already having that content, you might ping him (on your own post or on the question). Though only do that sparingly, and mention the main changes concisely.
Comment: From time to time I find myself coming back to my answer and thinking "goodness, I can add a paragraph to explain more or better".   This is not a
"significant change" in the sense of "rectified an error", but rather "this extra information likely will help".   Based on the answer below, I now understand that I can comment on my answer to make the asker aware, and I can see that this should be done sparingly: not for fixing typoes, but for adding significant useful information.
Answer: No, edits to existing answers to a question do not trigger a notification to the person who wrote the question; they're notified of new answers, edits to their question (or to an answer they wrote, if it was self-answered) and new comments to either the question, or its answers.
There is, however, a feature request to have the OP notified of answer-edits: Could we have a way to notify users when an answer is edited?
Current practice seems to be to add a comment, along the lines of: "I updated my answer based on (new information, new requests, clarifications)."
I, personally, try to explain the updates (and the rationale for the updates/edits) in the answer itself as I edit it, others find it more appropriate to explain that in the same comment notifying the OP of the edits. I'm not sure either approach is necessarily best, so long as the edits are explained somewhere.
Comment: Having read this answer, I now know what I needed to know (thanks).  In addition, I think I lean in the direction of "the status quo is good" ... if you need to notify the asker that you edited, you can (by making a comment) ... but if you were just fixing a typo you don't end up spamming them with a notification.  I like that.
Comment: A workaround even useful for others than the asker. And thus an addition.
Comment: Anyone having favorited the question can look at his favorites to determine which of them had any changes (Q+A+Comments).
Comment: True, but...was that a criticism of my answer (or an omission therein), or a workaround for the lack of notifications?
Comment: Are question authors really/still notified about comments under other people's *answers*? And that comment you mention as common practice, do you mean under the answer or under the question? (Btw, in either case, such a comment risks getting deleted, particularly under the question, where it's rather inappropriate.)


In simple terms, what are the major differences between P2WPKH and P2WSH bech32 addresses?

Question: I've read over the bip173, bip141, and bip143 specifications and they're a bit too technical to get at the simple answers I'm looking for.
Comment: Are you asking about the differences between P2WPKH/P2WSH in general, or about the differences between their corresponding address formats?
Comment: In short, both.  As you can see, I've added some of the research I've done over the past month or so.  I'm programming a bech32 encoder/decoder in perl, but also trying to understand bech32, segwit, P2WPKH, and P2WSH beyond simply porting the code from the node/c++ code in bip173.
Comment: Also, there were few simple and concise answers that I could find with a google search that correspond to bech32 validation and how bech32 relates to SegWit, so I wanted to share the conclusions I came to.
Answer:
P2WPKH - This stands for "Pay To Witness Public Key Hash" and the scriptPubkey is OP_0 0x14 {20-byte-hash}, where OP_0 is the version, byte 0x14 is the size of the data, and the {20-byte-hash} is a HASH160(PubKey).
P2WSH - This stands for "Pay To Witness Script Hash"  and the scriptPubkey is OP_0 0x20 {32-byte-hash}, where OP_0 is the version, byte 0x20 is the size of the data, and the {32-byte-hash} is a SHA256(script).

This data is taken from: http://bcoin.io/guides/segwit.html

Examples:
For the P2WPKH address: "bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4"
OP_0 , 0x14 , HASH160(PubKey) -- looks like (in hex):
00 14 751e76e8199196d454941c45d1b3a323f1433bd6
For the P2WSH address: "bc1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3qccfmv3"
OP_0 , 0x20 , SHA256(script) -- looks like (in hex):
00 20 1863143c14c5166804bd19203356da136c985678cd4d27a1b8c6329604903262
Examples taken from http://bitcoin.sipa.be/bech32/demo/demo.html and https://github.com/sipa/bech32/blob/master/ref/c%2B%2B/tests.cpp
Comment: Not MD5 (lol), it's SHA256.
Comment: Ah, thanks!  I thought md5 sounded wrong myself!


Is it technically possible to change the total amount of Bitcoin?

Question: Also, is it possible to change the reward cycle duration or the number of mining- reward coins?
Comment: related: https://bitcoin.stackexchange.com/q/38994/5406, https://bitcoin.stackexchange.com/q/161/5406, https://bitcoin.stackexchange.com/q/8439/5406
Answer: Technically, yes, yes, and yes.  However, I'm not sure if we'd still call it "Bitcoin" at that point.
Any of these changes would require a hard fork, which means that the underlying rules of the system are changing in a non-backwards-compatible way.  It means that blocks/transactions from after the fork are not guaranteed to be considered valid to nodes running software for pre-fork.
So, to change Bitcoin like this in practice would require convincing the entire rest of the world to agree with the changes.  Anything less, and you will end up with two versions: the original and the one with your changes.  Which one gets the title "Bitcoin"?  I don't know.  That's a non-technical question, and a point of contention.
For an example of this in practice, see Bitcoin Cash.
Comment: that means : change is possible technically, but it required to be soft-fork nor it will cause a new hard-fork . thank you for your clear answer. my question was because i have thought about what bitcoin situation will be if its price decreased to a low levels for long years from now and  may its mining rewards will  become uneconomic .so there are many solutions to avoid that .


Do insects' muscles become stronger with exercise?

Question: I am curious to know if insect muscles become stronger with exercise, because I have seen many insects get tired out, but I have never seen one get stronger. They always seem to become permanently weakened from excessive exercise. Do they get stronger like people do?
Comment: Would be interested to know how you might "see" one get stronger. As is the case with most wild animals, generally existing (scavenging, hunting, browsing, etc) requires exercise, and barring illness or old age, most animals are likely to be fit, but not fitter than necessary - building muscles becomes a waste of time after a certain point.
Answer: There are instances of insect muscle growth in response to increased use. The flight muscles of the tsetse fly (Glossina morsitans) have been observed to grow at a faster rate when subjected to enforced exercise (Anderson and Finlayson, 1976). Also larger mandibular adductor muscles (which power the feeding apparatus), and associated head capsule have been noted for caterpillars and grasshoppers feeding on particularly hard grasses (Bernays, 1986). However these examples occur immediately post-eclosion (i.e. after emergence as adults), and during immature stages respectively. Insect muscle typically grows during larval/nymphal (immature) stages, and often for a brief period at the start of adulthood - known as the teneral period. During immature stages, insects typically have a flexible membrane to allow for tissue growth and expansion, this can also be the case during the teneral period, before the inflexible exoskeleton has fully hardened. However at full maturity, insect growth is limited by the rigidity of their exoskeleton.
As far as excessive exercise is concerned, that some insects may be weakened permanently may be more to do with the fact that their life strategy is different to ours. Due to the vast number of offspring per adult, and subsequent low survival chance of any given individual, there could be an evolutionary advantage for individuals pushing themselves to possibly deadly extremes. This could lead to many deaths, whilst retaining a viable population and thus accelerate the emergence of a population of fitter individuals.
References

Anderson, M. & Finlayson, L.H., 1976. The effect of exercise on the growth of mitochondria and myofibrils in the flight muscles of the tsetse fly, Glossina morsitans. Journal of Morphology, 150(2), pp.321-326.
Bernays, E.A., 1986. Diet-Induced Head Allometry among Foliage-Chewing Insects and its Importance for Graminivores. Science, 231(4737), pp.495-497.
Comment: What about the butterfly ripping out from the chrysalis?


How did Earth's atmospheric layers get their names?

Question: How are atmospheric layers named once they have been discovered?
Comment: I was thinking more along the lines of why a specific name is chosen.  If there is an institution that selects the names, that would be an interesting point, but why do they chose a particular name for a given layer?  I would guess that there is some correlation between the meaning of the name and the properties of the layer.
Comment: Just to make sure: You are asking for the persons/institutions who gave the names to the atmospheric layer? Thus, you do not want to know what their names mean (you probably know it) but who gave it?
Answer: Who gave the names Troposphere and Stratosphere
The stratosphere was firstly discovered by Léon-Philippe Teisserenc de Bort and Richard Aßmann (they did not cooperate) around 1900. Teisserenc de Bort denoted that layer as 'zone isotherme' in his publication on his discovery. However, he published in French. I remember to have read somewhere - not sure where - that he gave the two names 'troposphere' and 'stratosphere' to the two lower layers after discovering the existence of a quite distinct second layer. Unfortunately, I do not find the reference anymore. In the article Hoinka (1997) you will find some information about the discovery of the stratosphere.
What the Names mean
Troposphere
tropos (greek): turn(ing)
Turbulent mixing is relevant in this layer of the atmosphere => Turbulent Mixing Sphere => Troposphere
Stratosphere
stratum (latin): something which covers something else (pavement, blanket)
This layer of the atmosphere, which is not dominated by turbulent mixing, covers the lower turbulent layer => Covering Sphere => Stratosphere
Mesosphere
mesos (greek): middle
This part of the atmosphere is the third of five (from humans defined) layers of the atmosphere => Layer in the middle (not by distance/height but by counting layers) => Mesosphere
Thermosphere
thermos (greek): warm, heat
This layer can be heated to above 1000 °C by the sun. However, it does not feel 'warm' because of the low 'air' density. => Heated/hot layer => Thermosphere
Exosphere
éxo (greek): outside, external
This layer is the most outward located layer of the atmosphere. => At the outer side located => Exosphere


Does CDATA preserve all escaped character sequences in XML?

Question: Do XML parsers translate escaped characters such as
 and
 even when they occur in CDATA?
I was confused by the answer to this question: Does the XML specification states that parser need to convert \n\r to \n always, even when \n\r appears in a CDATA section?
...because it quotes from the spec saying that sequences like #xD #xA are replaced with a single '\n' character, but then goes on to say that using
 and
 is a reliable way to preserve the characters. Is the semi-colon significant? (I don't have time to study the XML spec)
Also, I am aware that the 2 characters above are carriage return and line feed, and that they are normalized to just line feed by XML parsers - if the rules for what happens inside CDATA for line breaks is different to escaped sequences in general, then I hereby ask both questions!
Thanks,
rp
Answer: Nope. The parser does not touch anything in a CDATA section.
The semicolon does not make a difference.
Comment: This is incorrect. Newlines in CDATA are normalized (https://www.w3.org/TR/REC-xml/#sec-line-ends). "before parsing" means that the normalization occurs without knowing if the content is CDATA or not.


External HDD troubleshooting

Question: My external HDD is not working. It doesn't detect in Linux, I even did smartctl which didn't show up the manufacturer's name of the HDD . I think something has gone wrong. It's 4 years old. Is there any way I can troubleshoot it before I discard it?
Answer: Can you hear it spin up when you plug it in? Does it make any other noises, like clicking or ticking?
There's a chance that the electronics have gone bad but the disk is OK, especially if it's not spinning up. You could try taking the enclosure apart and connecting the disk through a different USB adaptor if you have one.
Don't spend too long on trying to recover flaky disks, you're best off just replacing them. Once they start to give a problem they don't last much longer.
Answer: First of all check harddisk platters are spinning or not.. If not then harddisk is not working.
if hard disk have power then try following stuff..

Try another USB port. Or do you have another OS ?
If your OS won't mount your USB drive, you can mount it yourself.
Plug in the USB pen.
In terminal type: # fdisk -l (so that you will see the device such as: /dev/sda1)
Mount it: # mount /dev/sda1 /mnt/temp (you have to make sure /mnt/temp exists

follow this link for more stuff.
steps that i follow..
first check hdd have power or not.
if it have power and working then ttach to pc and use some disk checking utility.
another option open disk case and attach this HDD with SATA/other cable to PC and try to run direct .. may be the HDD case is faulty...
hope these things help you..

External HDD troubleshooting


Platform independent Webform CiviCRM

Question: Is there any work being done on a platform independent Webform CiviCRM or equivalent? Our site is heavily invested in Joomla but we just can't seem to get CiviCRM to fit our needs without the customizability of Webform CiviCRM. I'm wondering if I will need to do a rebuild and migration to Drupal just for this plug-in or if there is hope in waiting, or places I can try to help.
Answer: There are some developments on generic ways of passing data between forms and CMS but they are at very early baby stages.
However they focus on the situation where CiviCRM is on a different server then the public website as this is the most secure configuration that best allows following European privacy guidelines. So that would certainly not help you right now.
Having said so, have you thought about separating CiviCRM and your public facing website because of security reasons?
Comment: I hadn't considered that before... seems like there could be some benefits, but it also seems like a pain to try to build a new Drupal site that matches my Joomla one, and then direct our users there for every donation, membership registration, or class registration. And then to not have the capability to include class lists, events, or fundraising campaigns on my main site.

We are planning a site redisgn in the fall, and this is tempting me to go Drupal even though we've already begun work on a new Joomla theme.
Comment: Agree it is a pain, but it does require a decision IMO :-)
Comment: There are significant advantages of using Drupal. One route we have done for a few clients who are already invested in eg WP or J, but need the bells and whistles that Drupal adds, is to skin up Drupal site to look the same, so it makes it fairly invisible when a user skips from one to the other, but agree that blocks of eg 'upcoming events' then requires iframe solutions if you want them on the non-CRM site
Comment: I think I'll test this out. I'm curious if all of the appropriate information will pass through if I use a Joomla wrapper. Could be a nice solution
Answer: Presently there is no platform independent Webform tool for CiviCRM, no.
One other option to use CiviCRM on a separate site, perhaps as a subdomain. Then you would have the issues of matching the look.
The other option is to use an iFrame on your current site which draws in a virtually un-styled Drupal "sub-site" which is just used for CiviCRM. This at least keeps the user on your main site and avoids the problem of matching your site's look.
Answer: Is there a way to use Angular Forms to do something similar?
My first thought would be Symfony forms to do this, but the dependencies are high.  There would have to be a Doctrine model for all the CiviCRM entities, and while there's a Symfony function for generating these it's only about 75% effective.  It would take a lot of work to complete the other 25% and test the whole 100%.  Thus, the thought that Angular Forms - already in Civi - might be an easier way.

Platform independent Webform CiviCRM


How do I cook any recipe with frozen eggplant?

Question: Four days ago I cut the ends off of a one pound eggplant, sliced it lengthwise, spread 1/4 tsp. of salt on each half, and left at room temperature (approx 65 degrees) for five hours.  Then I soaked up the liquid and brushed off each piece with paper towels.  At that point, I placed both pieces in a zip-close freezer (gallon) bag.  Now, do I thaw completely before using?  Thaw partially?  Cook straight from the freezer?  Any help would be appreciated!
Comment: Thawing would give you more consistent cooking times, if nothing else.  In some preparations (eg, frying), it'd also stop you from starting a massive fire.
Answer: If the slices are thin, you could bake/roast straight from frozen. I do believe the texture will be quite soft so use a parchment lined sheet if you wish to roast it. I like to brush a bit of miso mixed with honey on roasted eggplants.
Another option would be to lay it into a lasagna. I think this option is the most appealing. I wouldn't bother to thaw it if your slices are under half an inch thick.
If you sliced it only in half, such that you have two "boat" shaped halves, I would thaw it fully first. It'll take a while to thaw in such large pieces. Baba ganoush would be a good option in this case.
Answer: First of all you must thaw the eggplant completely.  Dry it off.  Then fry it up but since I am not supposed to give you a receipe, I would fry up onions, garlic, red peppers and other colors, anaheim chili peppers, all very soft, and some other veges you think may go good with this like carrots and celery and once that is done chop up the in nice cubes of the eggplants, fry them up till tender, add tomatoes or stewed tomatoes, more garlic, salt and pepper, a touch of jalapeno or chili flakes, then let everything on low and slow for about an hour, a little parsley and you should have something very delicious.  Next time don't freeze the eggplant and I do hope this all turns out very tasty for you.  You can also put on some plain yogurt on top mixed with some dill or mint, not both or even garlic.  Fry in canola oil only, eat hot or cold.


Custom webapps directory in Jetty

Question: I'm running Jetty through command line java -Djetty.port=8082 -jar start.jar. I need Jetty only for serving HTML files that would be viewed locally in web browser.
I wonder how can I specify the path to the directory where the HTML files are located? I mean the files are located in the location other than default Jetty webapps directory. Please note that I cannot manipulate files in Jetty directory.
Regards, Rafal
Answer: Try this Multiple webapps source

Custom webapps directory in Jetty


Best approach to show Risk data on UI - Simple divs or Guage (speedometer)?

Question: I'm working on a project where I need to show a Big Risk number on the main page of my website. What is the best approach according to the user perspective to show the number ? I have 2 options in mind , i.e. showing the number in a div and make the text color red/yellow/green (based on the high/medium/low risk) or I can place a d3 half donut chart (just like speedometer) having colors from red-->yellow-->green with a pointer indicating the corresponding color value based on low/medium/high risk. The Risk number will be shown under the chart.
Which option will fit best for user (should be attractive as well as simple) from ux perspective.
Also let me know if you think there would be any better option than these two.
Any help/suggesstions will be highly appreciated.
Answer: A progress bar kind of risk estimation can be used in this case so that the user can be provided with the percentage of risk in a visual form. More details can be provided to the user once they click the percentage displayed above the progress bar.
Answer: Besides being visually pleasing and interesting, the speedometer-style graphic also adds a third dimension (space, i.e. the length of the arc), in which the information is encoded. (The first two dimensions being: the numeric digit(s), and the color.)
Comment: I'm not worried about the space , as on the whole page I need to show the 2-3 speedometers and atmost 2 bar charts which can be managed easily within a single page.
Comment: My remark about "space" was related only to the addition of a third dimension of displaying the information: 1) numeric, 2) color and 3) space. It had no relationship with how much screen "real-estate" would be occupied.
Answer: There is a commonly held belief that static speedometer-style gauges are bad for getting a concept across easily or efficiently on a screen based business dashboard. This seems to have to do with the data to ink ratio and the ease with which people compare angles vs length of parallel lines.  e.g. refs: Not Gauges Again! and  If gauge charts are bad, why do cars have gauges?
While space might not be an issue, the ease of determining state 'at a glance' may mean you want to consider the simpler approach or alternatives to the gauge. At least make the 'ink' do more useful work.
Comment: Thank you @Roger your answer is really helpful. Voting up.
Answer: I can agree with all the information that is given on not using the gauges. But there's one user related question: Does the user know what the minimum and maximum risk number is? Is it a percentage and does everyone know if 50% is acceptable? If they don't know, the colours and even the gauge might be a good addition to make sure everyone knows what the numbers mean.
And another question: must the visual aid be very precize? If not, you might want to consider an indicator like these:

But ofcourse not with stars or hearts in front of the image. You could use 5 dots/circles instead of 7. Don't do more then 7 though, it makes the image visually complex for your users.
Comment: Thank you Maaike but its not really I'm looking for.


How are the other inputs chosen with MyMonero?

Question: Riccardo Spagni said in an interview somewhere (I will edit this if I find the right one) that MyMonero uses a different input selection algorithm than the official CLI and GUI wallets. How are the other inputs selected in MyMonero, and why is a different selection mechanism used?
Comment: See update - mymonero now uses `get_random_outs` from the daemon
Answer: Note: I am currently maintaining the Mymonero backend.
Mymonero currently selects outputs at random over the complete set of possible outputs. So guessing the real output is not necessarily trivial. The wallets try to select dummy outputs with a bias towards newer outputs, based on research indicating that there is a bias towards the real output being spent shortly after receival. Mymonero uses this alternative algorithm primarily due to historical significance (i.e. some past maintainer implemented it that way). I honestly did not think about this portion of the code until someone pointed it out to me ~2-3 months ago - it was in the "if it ain't broke, don't fix it" category previously.
More recently it has not changed because the required APIs from the daemon are binary and the web-facing client is written in GO. So grabbing the information is not "dead-simple". I was hoping the ZeroMQ patches would make it into v0.11 so that all calls into the daemon could be updated at the same time. But that patch didn't make it into the last release, so an interim solution may have to be applied now.
UPDATE: mymonero now uses the get_random_outs RPC from a monerod daemon.
Answer: I am not sure what is the method used by MyMonero but the reason to be diferent of the core its because its developed separately, the devs are not the same.. Tecnacly you could choose the inputs to mix with yours by hand, but I belive that  there is no wallet allowing this at the momment


Is the bird killing in The Prestige based on historical reality?

Question: In The Prestige (2006), there is a magic trick in which a bird is made to disappear and it is revealed that the bird is secretly killed by crushing it flat to make it "disappear". Is this trick from real history, or was it invented for the book/movie.
Comment: @Joshua ... that's not my take on it at all.  I think the trick with the cage on the table is meant to be "well known" and not particularly innovative (and yes results in a dead bird per time it is shown).  The version that Cutter invents has a hand-held cage, but still crushes the bird.  We are never shown the trick where the bird survives.
Comment: My understanding of The Prestige is guy #1 is doing it with a single live bird and guy #2 can't figure out how and decides that crushing birds to make the illusion is worth it.
Comment: When Cutter is walking Angier through the modified (hand-held) version of the trick, he ties a string to the bird's leg which pulls it out through the side of the cage as it's retracted into the apparatus concealed in Angier's sleeves.  During this walk-through, the (apparently same) live bird is then produced from behind Cutter's back.  I believe on stage the bird does die, but only because Borden (in disguise) sabotages it and causes it to misfire.
Comment: @iandotkelly: That doesn't disprove Joshua's point that it was _initially_ harmless to the bird, but then someone decided to just brute force it by killing birds, and it becoming popular, thus making it "well known and not particularly innovative" over time. This is remniscent of how urban legends are often born: the first one to tell the story know's it's a lie, but retellers thought it was true, eventually turning the tale into a "true story".
Comment: @Flater ... I don't understand.  Where does the movie show "guy #1" doing it with a single live bird and "guy #2" can't figure out how?  As far as I can see Borden is involved with another magician who does it traditionally with a table in one scene (and lies to the kid about the bird being fine) and Angier does an updated trick that doesn't use a table.  Each trick kills a bird, which is why they have a large stock of canaries.  I don't recall any indication that it was ever initially harmless (unless I missed something).
Comment: @iandotkelly: Just watched it... when Cutter demonstrates his version to Angier, it is clearly shown ("this is the best part") that the bird survives. This is also emphasized by the dialogue that follows where Angier is surprised he didn't have 'to get his hands dirty' after all. I interpret the cage thing as foreshadowing Borden and Angier's different approaches to magic. Borden uses simple techniques, whereas Angier uses technology to actually produce the desired effect.
Answer: It is based on a real trick, but the sources I provided do not conclusively state if any birds in these acts were ever killed. Only rumors and at least one inquiry, resulting in no substantial proof.
It appears the general nature of the trick in The Prestige is a variation of the real life, Vanishing Bird Cage:

The vanishing bird cage, also known as the flying birdcage, is a
  classic parlour magic effect that was invented by French magician
  Buatier De Kolta. The trick has also been used by magicians Carl
  Hertz, Harry Beardmore, Harry Blackstone (Sr. and Jr.) John
  Mulholland, John Angel, Sabrina Vera, and Tommy Wonder.
The magician displays a bird cage, holding it between both of his
  hands. The cage is rectangular, about six inches tall by six inches
  wide by eight inches long, and made of wire on all six sides. Often
  there is a bird, though in modern performances of the act it is
  usually fake, inside the cage. The magician will offer the cage for
  inspection by an audience member, but he will never actually release
  his grip of it. Then, without covering the cage, the magician makes a
  sudden motion and the cage (and anything inside) vanishes from sight.
  A variation of the trick was featured in the 2006 film The Prestige.

More Information:

The Vanishing Birdcage was a sensation and was also quickly ripped
  off. In the Summer of 1875 Harry Kellar is said to have purchased a
  cage from DeKolta's cousin for $750. Of course this was unauthorized
  because Buatier never sold cages to anyone.  This cage was probably
  the very first one outside of DeKolta's act, but it wouldn't be the
  last. In fact, Harry Kellar can probably be credited for the deluge of
  Vanishing Birdcages in America because he sold the secret to a magic
  dealer in exchange for props. In Europe a letter from Robert Heller to
  Charles DeVere the french magic dealer shows that the cages were
  already for sale in December 1875.
Harry Kellar stirred up a bit of controversy while in Australia over
  his presentation of "The Flying Cage" as he called it. Harry Kellar's
  routine was simple and direct, he counted to three and the cage with a
  live canary inside would vanish! A rumor circulated that Kellar was
  killing a canary every time he presented the effect. An inquiry took
  place and Kellar proved that was not the case. He showed that he had
  one bird and one bird only that he had been using for a long while.
  But this same controversy would come to haunt other magicians across
  the globe. In fact, this controversy was used as a minor plot point in
  the movie "The Prestige" in which they give a rather fictitious
  explanation on how the cage works.
Comment: It's still not clear from this answer though--in these tricks from history, was the bird actually crushed or not? Was Harry Kellar actually telling the truth? Did other magicians kill the bird even if Harry didn't?
Comment: It would probably be more accurate to make the first sentence "It is based on a real trick, but it's unclear whether there was ever any bird killing involved". The quotes should back up the answer, not be the answer in themselves (note the question specifically asks about the bird killing).
Comment: @spacetyper True, but it does at least suggest that there were inquiries, but nothing was ever proven and that The Prestige seems to have taken some large liberties. So far that's all I have been able to find, I'm afraid.
Comment: @DarthLocke I think OP means the trick that's done earlier in the film, where the birdcage collapses inside of a table. In that case it's explicitly shown the bird is crushed.
Comment: @NotThatGuy I originally had that in my post, but edited it out when I added new information that seemed to indicate that birds were thought to be killed, but the inquiry found in Kellar's case, no proof of it. But I will add it back in. :)
Comment: I'm not sure "fictitious" is an appropriate word to describe the explanation for how the trick works. That is, in fact, how the trick works. That there's another trick that works another way doesn't change that.
Answer: I did a little research on this question and it appears that the trick MIGHT kill the canary, or might not, but inevitably did result in a lot of bird deaths. Here is the notice:

The vanishing bird trick (which, I regret to say, kills a great number
  of canaries) is performed by means of accessories in which the costume
  plays a part. The bird cage itself is made to collapse into a cigar
  shaped tube. The centre of the cigar shape is naturally fatter than
  the ends, and, if the bird is fortunate, it is secreted there and may
  come out of the ordeal alive. Should, however, the bird get at either
  end it is crushed to death, or should the legs get through the bars
  they are almost certain to be broken. A conjurer once told me he had
  done the trick 200 times with one bird, but I should very much doubt
  it.
What happens is this. The bird cage is rapidly hooked to the end
  of a piece of whipcord, which passes up the sleeve and across the body
  of the performer, and then down the other sleeve, where it is tied to
  the wrist. It will thus be seen that the cord is considerably shorter
  than will be required to stretch from each end of the arms if they are
  extended. The cage, being in the performer's hand, is rapidly
  compressed and made to assume its cigar shaped form, and is dragged up
  the arm at lightning speed by the simple process of extending the two
  arms.
This very simple trick has puzzled millions of people. It is
  performed so rapidly that even if you closely watch the conjurer I
  doubt if you will know what he is doing. Afterward the conjurer
  usually pretends to find the bird among the audience. As a matter of
  fact he takes another bird out of his pocket, and by one of the simple
  dodges of conjuring appears to take it from some one's neck or head,
  or some other convenient place.
— Current Literature, Volume XIII, May–August, 1893, page 230
Comment: Is there a link to the source available?
Comment: @Longshanks Source appears to be [this book](https://books.google.com/books?id=ARQKoHBYRfsC&pg=PA230&dq=The+vanishing+bird+trick+(which,+I+regret+to+say,+kills+a+great+number+of+canaries)) (or a similar one), which is a compilation of newspaper articles. The paper named is _London Answers_, but I cannot find a newspaper by that name. Though when I searched for "the vanishing bird trick" on https://www.britishnewspaperarchive.co.uk/, I found that a version of the article was printed in the _Liverpool Echo_ on 25 February 1893.
Comment: It might be worth [edit]ing this into the answer. It might also help to at least explain how you found the note if you can't remember the exact source anymore.
Comment: @NapoleonWilson The source is listed. It is Current Literature magazine, June 1893. The article was originally published in "London Answers".


How do I export all contacts (names and phone numbers) to a text file on SD card offline?

Question: How do I export all contacts (phone, SIM) with phone numbers to a text file on SD card? Without Google, without connected computer, without network. Just save everything to a text file.
Answer: It is function integrated into build-in Contacts app.

Open Contacts
Switch to "Contacts" tab
Press the tree-dots button at the bottom
"Import/Export"
Export to storage
Check all checkboxes
Check file like 00002.vcf

This is a vCard file. One can manually open it in a text editor and search for contact names and phone numbers even if no special program for vCard is installed.
Answer: If you're looking to export all contacts to a single file, I recommend Red Rock Backup Contacts, which exports to Google CSV, Outlook CSV, or a custom CSV. It has no builtin restore feature, so you might need to connect to a network to restore them again with Google Contacts.
If you don't mind multiple files, I also recommend OBSS MCBackup, which exports to vCard (one file per contact) and does have builtin restore.
Both of these are easy to use and are free, and both of these apps export files that can be imported into most contact managers (not just Android ones).
Note that files created by these apps, like all Android files, are subject to a bug where you may need to restart android before they are visible over MTP to transfer to your computer.


Can you make cheese curds with pasteurized milk?

Question: I have this recipe for cheese curds that I want to try: http://www.ehow.com/how_5106352_make-cheese-curds-poutine.html, but it specifically calls for raw milk which is near to impossible to get here. I make yogurt with pasteurized milk and it works no problem, but does cheese somehow work differently?
Comment: Apparently pasteurization is not an issue - just made the yummiest tasting ricotta - which should be curds by tomorrow. And ehow may not be a "source of reliable information" TFD, but it's the best recipe I found, and it tastes great!
Comment: recipe could be fine, plenty on ehow is. It just how they get that information, and supporting it with links. Enjoy
Answer: ehow is not a source of reliable information. It is a content farm, and therefore most of it's articles are effectively screen scraped (either by hand or using 'bots). People get paid to make content, but there is no peer review process
There are plenty of other sources on the web including this site :-) that explain the cheese curd (paneer) process, and that you can use pasteurized or even milk powder with perfect results
Raw milk is NOT a requirement to make curds, and in a blind test is not identifiable. The taste is affected by the fat content and the cows diet. How well you extract just the whey will also affect texture and taste
How do you make paneer?
Search SA for Paneer
Comment: @Scivitri this post is all about cheese curds, not matured cheese. Anyway, I live in a country where we have real milk (free range grass chomping cows) and pasteurized and unpasteurized cheeses, there is **NO** observable difference other than marketing and price, how typical :-). Cheese usually tastes better when correctly aged, it's as simple as that
Comment: This is true. Pasteurization does not harm cheese making. Homogenization does make a difference and sometimes calcium chloride is added to homogenized milk to strengthen the structure or the curd.
Comment: While I agree with most of this, pasteurization does change the milk, and will have an affect on the resultant cheese.  I'll believe if all you're after is curd the results could be hard to distinguish, but in a full-grown, aged cheese, the differences are quite apparent.
Comment: As do I. I grew up working on dairy farms, and have worked in cheese production. As I said, I agree with most of your points; and I understand this question is principally about curd. I simply wanted to correct an impression your answer could give about aged cheese. The nature of the milk used has a distinct effect on the result. But you can look at http://www.worldchampioncheese.org/_apps/contest_results/ if you want; Baby Swiss is specificially swiss made from pasteurized milk, and types which are broken up by mold are dependent on the milk. If professional judges care, it matters.
Answer: What they probably meant to say is not to use ultra-pasteurized milk (aka UHT). UHT milk won't form proper curds, they come out small, grainy and unpleasant. I learned of this when I bought a cheesemaking kit, and actually experienced it by mistake in my excitement to try a new toy.
Answer: I have found that pasteurized milk will make excellent curds as long as the milk is not ultra-pasteurized (UHT).  I use non-homogenized whole milk that has only been Vat or Batch pasteurized.That pasteurization process does not kill the bacteria necessary for proper curdling or coagulation of the milk. This type of milk produces the same quality of curds as does using raw milk. This type of milk can be purchased at any health foods store.


How local is the stress tensor?

Question: I am confused by the definition of the stress tensor in a crystal (let's say a semi-conductor), I don't see how it could be "more local" than over an unit cell. I know that in field theory the stress tensor, or more precisely the whole stress-energy tensor, is local function, a function of the point $\vec{x}$ but I don't understand the interpretation you can give to shearing a point. Plus, in the lattice case I stressed (pun semi-intended), you shouldn't be able to look at displacements or deformations on smallest scales than your elementary cell?
Answer: An interesting question.
You are right, the stress in a crystalline solid, or any solid, is treated by engineers as a macroscopic property of matter assuming matter is a continuous medium. It is given in terms of the external forces acting on the solid per unit area at some direction. Hence the distinction of $\sigma_{xy}, \sigma_{yz}$ etc. This goes with the definition of stress
$\sigma_{ij}={\frac {dF_i}{dA_j}}$
where $dF_i, dA_j$ are Cartesian tensors (not like the general contravariant and covariant tensors in general tensor analysis as in GR.) This derivative is meaningful locally and, as said above, treats the solid as a continuous medium.
In order to define stress in terms of the crystal structure you can relate it via the strain tensor, which can be defined in terms of relative infinitesimal displacements of the atoms in the cell. There are a couple of ways of doing this, one of which is the Lagrangian description. In this, the coordinates $(x_1,x_2,x_3)$ of the atoms in the unrestrained state are taken as the independent variables, while $(u_1,u_2,u_3)$ are the relative displacements of the atoms, and they are the dependent variables. This  leads to the following definition for the strain tensor (Langrangian strain)
$\eta_{ij}={\frac 1 2}( {\frac {\partial u_i}{\partial xj}}+{\frac {\partial u_j}{\partial x_i}}+\Sigma  {\frac {\partial u_r}{\partial x_i}} {\frac {\partial u_r}{\partial x_j}} )$
where the summation is over the index $r$. Note that this is a function of the coordinates of the atoms in the lattice, so $\eta_{ij}$ is a locally defined quantity.  Macroscopically strain and stress relate via Young's modulus $E$ in the relation $\sigma=\epsilon E$ (Hooke's law,) which would be ok for an isotropic material, in which direction of application of the force is irrelevant.  For anisotropic materials, such as crystalline solids  in condensed matter physics, this relation is generalised to the following
$\sigma_{ij}=\Sigma C_{ijkl}\eta_{kl}$
and the summation is assumed over the $kl$ indices. The coefficients  $C_{ijkl}$ are the second order 'elastic constants' or elastic stiffness coefficients of the material, and they are fourth order tensors, defined as derivatives of the elastic energy of the material, i.e. the potential energy of the atoms in the crystal lattice due to their relative displacements. I think this is what TMS meant in his comment.  I hope this helps to understand the notion of locality of stress in crystalline solids.
Answer: You right, you can't, when we defining stress-energy tensor like that we suppose that we have everywhere solid, continuous matter inside the object.
And when we want to incorporate the discrete structure of crystal, we usually doing that in a "smooth" way by using the function of Radial distribution function of atoms in crystal cells.
This can be justified by noting that we are usually interested in the potentials between the atoms when we try to study physical properties of the crystal, not the atom's locations itself, which in its turn can't be determined precisely as you know and makes no sense.
Comment: I don't know the term "radial destitution". Maybe autocorrect played a trick on you?
Comment: Yes, corrected thx.

How local is the stress tensor?


Creating an administrator webpage for a Facebook Flash game

Question: I am creating a Facebook Flash game where the application will be run on my server and will be displayed in Facebook using an iFrame. My question is: How do I administer the application. I'd like to do things such as see reports, the ability to ban / kick users, etc. How would I go about doing this? Does Facebook provide any in-built facility to do this?
Answer: I believe you have to create a separate page to administer your database for banning of users/ reading the daily user amount etc etc


An invertible matrix

Question: Given Matrix $A$, checking that its diagonal elements are nonzero or whether its determinant is nonzero, can we say the matrix is invertible for sure? Are there other properties that by looking at the matrix you can tell whether it's invertible or not?
Answer: If you notice that two rows are scalar multiples of one another, then that would lead the determinant being zero, and therefore the matrix would not be invertible.
Example: $\begin{bmatrix}1&2&3\\2&4&6\\12&2&3\end{bmatrix}$ is not invertible because rows $1$ and $2$ are scalar multiples of each other. Also, as for checking if the elements on the diagonal are non-zero, this only works if the matrix $A$ is already simplified to Reduced Row Echelon Form, because if two rows in the matrix were linearly dependent, then the RREF of the matrix would have a row of zeros.
If the determinant is non-zero or if the matrix has $n$ pivot points (for $A_{n\times n})$, you can say for certain that the matrix is invertible.
Also, for your question about other properties that a matrix might have that would indicate invertibility: the following are equivalent, so if you notice any of the properties below describe your matrix, then your matrix is invertible.
$(a) A$ is an invertible matrix.
$(b) A$ is row equivalent to the $n \times n$ identity matrix, $I_n$.
$(c) A$ has $n$ pivot positions.
$(d)$ The equation $Ax=0$ has only the trivial solution.
$(e)$ The columns of $A$ form a linearly independent set.
$(f)$ The linear transformation $x\to Ax$ is one-to-one.
$(g)$ The equation $Ax=b$ has at least one solution for each $b\in\mathbb{R}^n$.
$(h)$ The columns of $A$ span $\mathbb{R}^n$.
$(i)$ There is an $n \times n$ matrix $C$ such that $CA=I.$
$(j)$ There is an $n \times n$ matrix $D$ such that $AD=I$.
$(k)$ $A^T$ is an invertible matrix.
Comment: Thank you, could you please provide an answer to my other questions as well?
Comment: Aren't the two statements "n pivot elements" and "nonzero diagonal elements" equivalent?
Comment: A pivot position in a matrix is a position in the matrix that corresponds to a leading $1$ in the reduced row echelon form of $A$.

So I suppose the difference is that pivot position is specifically for the matrix in RREF, while jut saying non-zero diagonal elements doesn't necessarily mean the matrix in RREF.
Comment: By Echelon form, are you referring to Gaussian elimination method?
Comment: Yes, I am. After using the Gaussian Elimination a certain amount of times it should be in RREF.

An invertible matrix


What does "de-bearding" mussels mean?

Question: Have come across this in quite a few recipes, that mussels need to be cleaned and de-bearded. First time cooking shellfish so just want to be sure I know what they're talking about. Thanks.
Answer: The beard is also known as byssus threads. They are the filaments that the mussel uses to secure itself to hard surfaces. They are usually brownish and may appear somewhat like seaweed. Most mussels commercially available have been farm-raised so often the beards have already been removed during processing. If you have beards, grasp them firmly and pull towards the shell hinge until it comes out. You may need to use a dry paper towel to increase your grip as they can be slippery.
Comment: Firmly is right; it's important to pull slowly. Yanking will sometimes pull flesh out along with the beard.
Comment: Pliers can also work if you can't get a good grip : grab the beard with the pliers, then rotate the pliers so you slowly pull the beard away from the shell.
Answer: De-bearding simply means removing the seaweed-like fibers found sticking out of the shell.  Usually you can just pull it off/out with your fingers.  This is less of an issue with farm raised mussels.  I usually rinse and quickly take a look at each one, discarding broken mussels and de-bearding the ones that need it.
Comment: I agree that the question doesn't ask explicitly what the beard is but I still don't think it's a good thing to have factually incorrect answers. I also agree that your edit has fixed the problem so I've undone my downvote and removed my comment.
Comment: My edits should sufficiently answer the original question, since the OP did not ask for a definition of the beard, rather he or she wanted to know what the process meant.

What does "de-bearding" mussels mean?


Is copy number variation dynamic?

Question: Is there any evidence showing that copy number variation changes over time? I'm wanting to model interactions in expression level as a dynamic bayesian network, but an assumption my approach will need to make is that it is static.
Comment: the answer to this question depends on the scale you're looking at: individual cells? tissues? organisms? tumors?
Comment: @MichaelKuhn Good clarification point, thanks for bringing it up. I'm thinking of changes in the output of whatever technique is measuring CNV--e.g., in situ hybridization, etc.--in a given organism. I assume that data is averaged over multiple cells, but I'm not taking about variance due to the averaging process. You're tumor point is good as well, as I'm interested in variation the cancer genome. Does that help?
Answer: Your question could be phrased more specifically to avoid ambiguity, but rephrasing it the way that I suspect you mean it, ("Is there any evidence showing that [the rate of] copy number variation changes over time?"), then yes, there is indeed.
The rate depends on many factors including which mechanism and which organism and which region of the organism's genome and as @Michael wrote, also what scale (et. al.) is under consideration too.
So your assumption that the rate is static should probably be stated explicitly.
Nature Reviews Genetics 10, 551-564 (August 2009) | doi:10.1038/nrg2593
Comment: Thanks, Kevin! That's mostly what I was looking for, and it looks like this review will give me some more information as to how it works. As a side note, I'm interested in modeling regulatory relationships in time series of expression data, but was curious as to whether, if I could get CNV data for my model as well, if those data could be assumed to be fixed over time, or if that would just have to be a limitation of my approach.

Is copy number variation dynamic?


Crash recovery for Safari

Question: I lose my tabs when Safari crashes. Is there any way to recover them? Firefox, Opera and Chrome all have this enabled by default, but Safari doesn't seem to have this ability.
Answer: The History menu has the option "Reopen All Windows from Last Session."
I prefer the plugin Saft, which among other things does this automatically, and it even works after Safari crashes.
By the way, the most likely cause of crashes in Safari is Flash, so using Click to Flash will cut down on Safari crashes significantly.
Answer: There is also an AUTOMATIC and configurable RESTORE Extension that takes less then a minute to install.
SafariRestore - what a reasonable name. It's donation ware. You may also go to safari extension gallery to browse more apps, you get there by selection of "Safari Extension Gallery" tag under the safari menu located at the left top of your screen... click safari, it's under 'about safari.

Crash recovery for Safari


Boot time on Mountain Lion

Question: I have my MacPro Quad and upgraded to Mountain Lion.
I have cloned the system hard disk to bootable external HD.  I have tried it and works fine.
Now when I have put the external HD in the BAY I to use it as my main HD the booting time is very long.
How can I reduce the booting time?
Many thanks in advance for your assistance.
Michel
Answer: Since you have moved the system disk around, the Mac doesn't know where it is so it takes a few seconds to look for it.  You need to tell the system which disk will be the boot disk and where it is located.  After you have moved the disk to the bay, Open the System Preferences>Startup Disk window and choose the bay disk.  When you restart, the Mac will know exactly where the boot disk is and your bootup time will be a lot faster.

Boot time on Mountain Lion


Was beer conceived to be a bitter drink?

Question: In all the years of my life (except when I was a minor), I've never tasted beer that's not bitter. So was beer conceived to be a bitter drink? What factors in the bitter taste of beer?
Answer: So I'm going to assume you mean historically...
The Wikipedia page has a ton of good info but basically, beer was originally a very sweet beverage due to the wild yeast and under modified malt that was used in the brewing process.  To combat the sweetness, brewers would use Gruit which is an herb mixture to bitter the beer. Hops were also used as a bittering agent, but not to the same extent as gruit.
In 1842, the first Pilsner was brewed, a style which showcases hops and is very pale in color which was revolutionary at the time.  This style took Europe by storm and the migrating Germans to the US brought this taste for hoppy pilsners with them to the US.  There were many competing styles that were popular in the US up until Prohibition.
 After prohibition, the breweries that were still in business chose to produce the beers that appeal to the widest consumer base, I.E. Pilsner drinkers. This is the raison d'etre for the very large breweries.
As for the bitterness in beer, the most common factor is Hops.  Hops contain different acids (Alpha, Beta, Myrcente, etc) that bitter beer in different ways.  The type, quantity and usage of hops in the brewing process can affect the bitterness of beer.
That being said, some styles don't use a lot of hops if at all.  Scottish/Irish ales, for instance, don't have much hop flavor due to the lack of availability of hops in the region.  Other styles originate from locations that have never seen hops.
Hope this helps.  Never be afraid to try new things.
Comment: Yep, I meant historically (hence the history tag). Good answer with enough details.
Comment: I assume it's not what you meant, but the way your 2nd paragraph is written seems to imply that 1842 was the first time that hops was used to bitter beer. According to wikipedia, "Hopped beer was perfected in the medieval towns of Bohemia by the 13th century."
Comment: @ThePhoton, You are correct.  Hops were used well before 1842, [link](http://www.beerscenemag.com/2010/04/the-short-and-bitter-history-of-hops/) but it wasn't until the popularity of the Pilsner style that hops truly supplanted gruit.   I'm drawing a blank as to re-wording it.  Suggestions?
Answer: Beer is not always bitter, but the bitterness (usually from the hops) is there to counter the sweetness of the malt.
Some beers, like the Belgian Strong Ales, tend to be malty & sweet, with just enough bitterness to but the sweetness.
Beers become sweeter with age, as the hops (and the bitterness) drop out, leaving only the malty sweetness.
Gruit (beers made without hops) use different herbs to give bitterness to the beer.
Answer: It is rather hard to say what should be in beer making as much of beer making is just a exercise in the personals taste of the brewer but yes a certain level of bitterness is required to counter act the sugars that need to be present for fermentation.


Did changing the site's name reduce the number of bad questions from new users?

Question: A few years ago, this site was called WordPress Answers. After much negotiation, the Community team agreed to rename it to WordPress Development. That change occurred around March 1, 2014, so it's been just over 2 years. Do we have any evidence that anything changed as a result? In particular, did the change stem the tide of unwelcome questions from new users?
Answer: I'm writing this as an answer and not in the question itself because I'd love to see some counter-evidence. You see, I'm skeptical that name changes will make any difference to the way sites are used. (This doesn't mean I haven't suggested the move myself.) This site could be a data point confirming my suspicion that name changes do not noticably change new user behavior.
One of the things that concerned us about the name change was that it would discourage some potential new users (including some who are potentially valuable) from joining the site. The data does not show that fear to be justified:

(Note: each image is linked to a query on the publicly available database similar to the internal database I used to generate the data. This one happens to be identical, but others differ because the public data limits access to deleted posts.)
There was no real change in the rate of new users joining the site in 2013 or 2014, but there was accelerated growth in 2015. So I don't lose any sleep over the name change from the perspective of the user base.
For the purposes of this study, I'm going to set an extraordinarily low bar for a "good" question:

It must not be deleted and
It must not be closed.

All other questions are labeled "bad". I'm only looking at questions from new users asked within two months of creating their account. I'm also looking at accounts created in 2013 and 2014 to fit into the relatively stable influx of new users. Overall, the gap between open questions and closed/deleted questions actually narrowed after the name change:

Looking 90 days before the change and 90 days after, we can quantify the difference it made in terms of question quality:
<code>Era   Good   Bad   Delta
---   ----   ---   -----
pre   1293   997     296
post  1158   955     203
</code>
While there are fewer closed and deleted questions immediately after the name was changed, there were fewer questions overall. If anything, new users asked worse questions on average after March 1, 2014. It's also clear y'all spend considerable effort clearing out questions that are not answerable or useful. So the frustration with a less-than-ideal name was certainly justified.
This isn't to say the new name didn't help. But the effect was marginal and completely washed out by larger trends in what people ask about and how. For instance, a common complaint on this meta is with WooCommerce questions. These are officially off-topic and yet they have become more common over the years:

People increasingly asked about WooCommerce in the months leading up to the name change and continued after it. The trend almost certainly has more to do with things outside of our control (such as changes to WooCommerce's support system) than anything in our power.
Summary
There may be many reasons to change a site's name, but the data from this site's name change indicates we should not expect it will increase the quality of questions from new users.
Comment: Thanks for this, this is pretty neat! Since it has WordPress in the name mean we'll always be just another medium to cross-post their WP Support Thread for more attention or faster turnaround, a general userbase. I unfortunately don't think there's a much we can do. Since the site allows anonymous posting - there's no real preface or "Hey, read this before posting please otherwise the question may not be received well." - The Woo questions are surely because, surprisingly, such a popular product does not have open support forums anymore. Granted, the ones they had were atrocious but functional
Answer: I think it might be summed this way - software developers (at least the good ones) like a descriptive unambiguous names. This does not by itself prevent bugs or help solve them but it does help in getting a general idea on what a thing is without a need to scan the code (or FAQ) to find out.
It probably do not make any difference to new users which spend 1 minute writing a bad question even if they know it is off-topic, just because there is a chance someone will answer them, but my gut feeling is that there are almost no trivial wordpress usage question, and even the off-topic ones are in some development related context even if it is still off-topic.
Even woo-commerce is not a black and white  thing and those questions might get an on-topic answer because while the question might be in the context of woocommerce, it comes from misunderstanding or lack of knowledge of some core principal of wordpress.