What is the typcial descent rate of a helicopter?

Question: I'm not a pilot, just asking out of curiosity. What is the typical descent rate for a helicopter when landing? I found the answer of 300 feet per minute on the web, but I want to confirm this. If this is true, than a helicopter descending from 2400' to land would take 8 minutes. Is this correct?
Answer: That is of course dependent on airspeed at approach, and the approach angle. I have a flight manual of an older type helicopter, I cannot reproduce the contents, but it shows True Airspeed on the horizontal axis, Rate of Descent on the vertical, and a set of inclined lines for the angle of Descent.
In the Emergency Procedures - Normal Approach, an Angle of Descent of 8 - 10º is specified, and a typical TAS of 65 knots. This amounts to a Rate of Descent between 800 and 1100 ft/min. Maximum allowable ROD at that speed is 1600 ft/min which is marked as Approximate Autorotation.
Comment: Thanks. Doesn't "Emergency Procedures" imply higher than typical rate of descent? This would suggest that normal rate of descent is lower.
Comment: Yes it would, although use of Normal Approach would suggest, well, normalcy. The normal angle of descent seems to be 8 - 10 deg for this helicopter, a Huey. Could not find any other references to a normal descent rate in it.
Comment: It also depends upon the exact aircraft make/ model/ equipment as a "normal descent" can put you in the bad area of the height-velocity diagram for potentially a long period of time in certain circumstances. Managing the risk of that versus a descent that is not particularly stabilized is the art of flying. In the particular helicopter I had trained in, with a stabilized approach from about 50' AGL to 6' AGL you were in the bad area of the H-V diagram and if the engine fails it's really going to hurt.
Answer: The 300 feet per minute rate is the maximum descent rate for a hover. In helicopters, it is the rotor that is providing airflow downwards to keep the helicopter in the air. The air that has traveled through the rotor, downwards, keeping the helicopter aloft has become very turbulent air with a downward velocity. This means that it until it settles, it is not going to provide lift. If I'm in a hover, and I descend at a rate higher than 300fpm, then I can potentially descend into my own down-wash, and then the rotor stops providing lift. This is known as vortex ring state, or sometimes settling with power (Vortex Ring State is more precise, settling with power can occur for various reasons and in different conditions). If I'm traveling in some direction at a reasonable speed, I'll be moving away from the turbulent air that just went through the rotor, and the low descent speed no longer applies.
The calculations from the earlier post are reasonably accurate for an emergency descent. In an emergency landing (an autorotation, or power-off landing), the R22 emergency procedures state to establish your glide at 65 knots, with your vertical descent being controlled by what is required for me to keep the rotor spinning.
In a normal descent, my forward airspeed would be closer to 90 knots, and 8-10 degrees would be on the higher end for descent rates.
Comment: Helicopters use far more power in a hover than they do in forward flight. In forward flight, anything above about 30 knots, the helicopter starts developing translational lift, where the entire spinning rotor (the rotor disc) acts like a wing and generates extra lift. Due to both the translational lift, the restrictions on the descent speed in a hover, and the ability to merge with regular airport traffic, in most situations, helicopters will land in the exact same pattern as an airplane, except that we'll generally circle around in the opposite direction (making right turns instead of left).
Comment: Thanks. So what does a typical helicopter (e.g. for sightseeing) descending from 2400' do usually? Hover down for 8 minutes or adopt some kind of a spiral path to speed up the descent?


What are the different steps to certify a new aircraft in Europe?

Question: I know that to be allowed to fly an aircraft has to be certified by an agency and that this one is not the same for European or American (for instance) aircraft. What are the different steps that an aircraft designed to fly in Europe has to go through in order to be certified? Proof on the paper of some features? Ground tests (which one)? Flight tests (which one)?
Comment: It depends on the aircraft in question -- different aircraft are subject to different regulations by both the EASA and FAA.
Answer: The EASA certification requirements are all publicly available online. Actually proving that an aircraft meets those criteria will certainly include all the steps you mentioned although exactly what happens probably depends a lot on the specific aircraft and manufacturer.
Answer: It does really depend on where the aircraft is being designed and manufactured. The initial type certification is done with the authorities in the State of Design / Manufacture. If that country happens to be outside of the EU, EASA will identify what extra proof of compliance will be required to fulfil the European certification requirements.
Answer: For the most part, the EASA guidelines (as issued, for example, in Certification Memoranda, and the FAA guidelines (as issued in Advisory Circulars and in guidance to those acting for the certification authority, such as 8110.105) are pretty much harmonized.  (and that goes for the JAA as well.)  There are some minor spots whre EASA is either ahead of or behind the FAA guidelines; For example, there is a paragraph of EASA CM SWE?? - 001 [don't remember the exact number] (dated 2014) that deals with a small class of LRU issues and that is not yet in any FAA guidelines that I could find.
Even though the fundanentals are closely aligned, you still have to demonstrate compliance to the FAA authority after having been certified under EASA, and vice-versa.  However, since the process of obtaining certification pretty much demands attention to keeping your paperwork in order, your testing comprehensive and well-organized, and your certification artifacts available, once you have passed in one context the remaining work to be certified in the other is at least 90-95% in place.


How do you make a Genesis block?

Question: What is involved in creating a genesis block? What makes it different from the other blocks in the chain.
Answer: There is only one (Bitcoin) chain, and the Genesis Block is the first block in that chain.
This block was created by Satoshi Nakamoto as the first link in the blockchain. It is hard-coded into the refernce Bitcoin client. To create it, it was "mined" like every other block, except it was at the minimum difficulty level, and contained arbitrary data.
The following quote from The Financial Times is embedded in the block's binary data

The Times 03/Jan/2009 Chancellor on brink of second bailout for banks

This serves to prove it was generated on or after January 3rd 2009, as well as a political statement regarding the global economy.
Comment: Today I learned.
Comment: Even though the Genesis block (almost) satisfies all rules that other blocks have to satisfy (and even more, see https://bitcointalk.org/index.php?topic=172009.0), it is not actually validated by full nodes. It's just a hardcoded starting point, and it would actually have worked just as well if it did not carry any proof of work.
Comment: @PieterWuille, Do you mean that any hash could qualify as the genesis block and we don't need zeros in front of it?
Answer: The genesis block is really nothing more than a block that doesn't have a previous block. Creating a new genesis block only involves setting the previous hash part of the block to all zeroes. Because it doesn't have a previous block, it's automatically the first block in the chain, and creating a new genesis block means that you create a new block chain.
There are actually four 'official' genesis blocks out there, one for the main Bitcoin chain, and there have been three 'test nets' so far. But there's nothing stopping you from creating your own genesis block (although it's pretty pointless).
Comment: Do you mind elaborating on these 3 "test nets"?
Comment: I was interested in trying to create on just to understand the process better.

How do you make a Genesis block?


why do energy stocks trade at lower prices compared to other sectors?

Question: In researching some additional stocks I want to acquire, I've noticed many energy stocks trade at lower prices and exhibit a large amount of volatility. Why is that despite the fact energy is a basic need like food and clothing?
Comment: Energy stocks have been beaten down due to the fall in commodity prices in the futers market.
Answer: Large-scale price range of a stock isn't directly meaningful; that reflects how many shares exist, not just how desirable they are. A stock split, for example, doubles the number of shares everyone holds while cutting the value of each share in half; that's meaningless except that it makes the shares a bit easier to trade in.
Change in price is more interesting. In the case of energy companies, that often reflects major changes in energy supply, distribution, use, or how well positioned people feel the company is for the next change in these. Fracking's surge and the questions raised against it, whether a major pipeline will or won't be built, international energy price trends, breakthroughs in renewables... if it might affect energy price, it might affect the company's strength, both absolute and relative to others.
In other words, the same kinds of things that affect any stock.
Comment: Check out commodities such as precious metals, they have large swings as well based on all sorts of global factors just like energy. The volatility of a stock is almost always tied to the questions and unknowns because they make it harder to calculate a fair value. Certain industries have many global and/or unpredictable factors, e.g. a US precious metals stock will swoon when there is a downturn in unpredictable China because they consume a lot of precious metals. A US utility has less volatility because it has a very consistent business with high barrier of entry and little disruption.
Answer: I don't know why stocks in some industries tend to have lower prices per share than others. It doesn't really matter much. Whether a company has 1,000,0000 shares selling for $100 each, or 10,000,000 shares selling for $10 each, either way the total value is the same. Companies generally like to keep the share price relatively low so that if someone wants to buy a small amount, they can. Like if the price was $10,000 per share, than an investor with less than $10,000 to put in that one stock would be priced out of the market. If it's $10, then if someone wants $10 they can buy one share, and if someone wants $10,000 they can buy 1000 shares.
As to why energy stocks are volatile, I can think of several reasons.
One, in our current world, energy is highly susceptible to politics. A lot of the world's energy comes from the Middle East, which is a notoriously unstable region. Any time there's conflict there, energy supplies from the region become uncertain. Oil-producing countries may embargo countries that they don't like. A war will, at the very least, interfere with transportation and shipping, and may result in oil wells being destroyed. Etc.
Two, energy is consumed when you use it, and most consumers have very limited ability to stockpile. So you're constantly buying the energy you need as you need it. So if demand goes down, it is reflected immediately. Compare this to, say, clothing. Most people expect to keep the same clothes for years, wearing them repeatedly. (Hopefully washing them now and then!) So if for some reason you decided today that you only need three red shirts instead of four, this might not have any immediate impact on your buying. It could be months before you would have bought a new red shirt anyway. There is a tendency for the market to react rather slowly to changes in demand for shirts. But with energy, if you decide you only need to burn 3 gallons of gas per week instead of 4, your consumption goes down immediately, within days.
Three, really adding to number two, energy is highly perishable, especially some forms of energy. If a solar power station is capable of producing 10 megawatts but today there is only demand for 9 megawatts, you can't save the unused megawatt for some future time when demand is higher. It's gone. (You can charge a battery with it, but that's pretty limited.) You can pile up coal or store natural gas in a tank until you need it, but you can't save the output of a power plant.
Note numbers two and three also apply to food, which is why food production is also very volatile.


Travelling within the US as a foreign citizen without a passport

Question: I'm travelling within the US and am a British citizen. Can I travel without my passport and just show my UK driver's license instead?
Comment: If you lost your passport, you should immediately seek out your consulate to get it cancelled and replaced. If you didn't, well, you needed one to get into the US, so why not use it?
Comment: @waiwai933 to avoid losing it, obviously.
Answer: TSA website has a list of acceptable IDs. From this I would read that only a foreign government-issued passport is acceptable for those travelling without the requisite US (or Canadian) forms of ID.
Answer: It's worth noting that if you're just driving, then you need either both forms of your UK driver's license if pulled over, OR the paper form + passport.
One point worth noting is that they're REALLY strict on PASSPORT ID for bars and clubs.  I've tried and failed several times to use a UK driver's license, and spoken with many travellers with the same problem.  Passport really is required.
Comment: +1 on the bars. I was always able to talk my way in using just the pink EU licence, but a lot of places seemed unhappy and would ask for passport instead.
Comment: oh really, that's surprising. I used a lot my national ID (I don't know if UK has both driver's license and national ID though) and most of the time it worked in the US. I didn't have a lot of happy faces but then I didn't take the risk losing my passport
Comment: I suspect this depends on how generally paranoid the business is in the first place.  Fines for letting anyone underage drink are punitive enough that some bars insist on checking the ID of all patrons; not simply those who look under 35 as the law requires.  The reason they're likely to get nervous about foreign ID is probably that they can't just swipe it in a cardcheck machine to verify that it's valid, nor do they have the training to identify anything beyond a really bad fake by visual inspection.
Comment: @Vince: UK does not have ID other than passport/driving licence.
Comment: Bars and clubs: these rules are set by the states.  They could be different in different jurisdictions.
Answer: The US has a number of circumstances where "government issued ID" is demanded and an "out of state" drivers license isn't good enough, escalating immediately to passport. This includes things like checking into a hotel, picking up your badge at a conference and (I am not making this up) buying medication for a head cold. Mark mentioned getting into a bar which is not an issue for me, but the point is that people want to see your ID rather more than I (a Canadian) expect them to, and if you're not local, they want to see a passport. If an internal domestic flight might not mind you using your UK drivers license, that wouldn't mean that once you got into the States you could ship your passport off for visa-getting purposes or whatnot, because chances are you'll need it pretty regularly while you're there.
Comment: But since you've tried to do these things with a Canadian license rather than an out-of-state US license, I'm skeptical that the latter would have been rejected. Most US citizens don't have a passport, after all. Next time I need some pseudoephedrine I'll try to get it in New Jersey with my New York license and see what happens. I don't remember ever staying in a hotel in the US that required ID, but a *hotel* refusing out of state licenses seems particularly odd.
Comment: If a driver's license is acceptable as ID then any US license will do, and usually any Canadian one will also be acceptable. The TSA is a notable example; they explicitly accept only US and Canadian licenses, so a UK license won't suffice. I've never seen a situation when only in-state licenses are accepted. Foreign licenses are generally accepted only as proof of being licensed to drive.
Comment: You've never seen, but I have, and I listed three of them in my answer. I have been asked for a driver's license, passed it over, and got "oh, I need one from [this state]." - not even I need a US one - and the person has then asked for my passport. The only time anyone has found my Canadian DL ok is renting a car in the US. As generic "id" they reject it.


How to Install an application that requires android 5.0+ on android 4.4.4

Question: I have a phone running android 4.4 and the app requires android 5.0 or higher. I want to install this app on android 4.4. Do you have any way, help yourself. Thank you very much.
Comment: Have you tried to simply contact the app author and ask if it is really necessary to exclude pre-Lollipop devices?
Answer: Sometimes an app has the ability to run on an old device, but there is also something in an app's apk file, indicating the oldest version that can install this app. For example, maybe an app CAN be run on android 4.4 but the author of the app set the minimum supported version to android 5.0.
So it is possible to change it. Afterwards the app might be able to run on old devices, while it may also crash.
An android app downloaded from Google Play or somewhere else is an apk file, which is actually just a zip compressed package, containing multiple files, e.g. dalvik bytecode, pictures, text resources. To learn more about apk file's structure you can just google it. One of the files is AndroidManifest.xml, that was originally a xml file before the author "compile" and publish the app. You don't have to know what is xml but it was "human readable" before being published and become unreadable when the app finally reached you. The AndroidManifest.xml have a line looks like android:minSdkVersion="8" , sdk version 8 means Android version 2.3, sdk version 23 means Android 6.0, search for "android sdk versions" to get a full list. Now however, this line had already been converted to something unreadable. We need something else.
One of those things is apktool, it can "decompile" an xml or even the whole app back to what we can read and edit, then "compile" it back to apk. There're plenty of blogs about how to use apktool so I won't run into details. Using apktool you can decompile the apk, change the minSdkVersion to a very small number or just 1, compile the app back, then install.
Notice:
1. You have to "sign" the apk after compiling it back. Google for details.
2. You have to uninstall the previously installed version of the app before reinstall the modified one.
3. Do not publish a modified apk, it's illegal.
4. Don't expact too much from this method. The app may still crash.
5. Though I often do this but it's really complicated for non-programmers to do the modification so feel free to ask, and prepare to give up at any moment.
Comment: Not only publishing a modified app is illegal. Actually modifying an app is illegal, too.
Answer: there is no way to run to run apps with higher from your android version try old versions of the app and the last option is rooting and it have so so many risk of bricking your phone so using old versions is the best choice
Answer: Upgrade the android even I had android 4.3 jelly bean I installed an AOSP for my device. The AOSP was android 7.2.2 nougat.
Now I can enjoy all the app that were not compatible with Android 4.3.
I am answering from the same device, don't worry about getting your device bricked even my device got into bootloop 2 times while installing. I fixed it by flashing with my stock ROM.
Before installing any custom ROM or even before installing custom recovery get the stock ROM for you device as a safer side, if you need any help go to XDA forum and get help from top developers.
Hope that helps..
EDIT -
I have Xperia M (C1905) you can check the official stock ROM for this device the last revision given by Sony was Android's 4.3, But a developer from XDA forum ported AOSP for Xperia M.
Thanks to that guy, If you need some proof I can add some links to the AOSP rom page.
Answer: Here's a possible workaround that worked for me with the Google Home app:

The Google Play store recognized the smartphone running Android 4.4.4 and would not install the latest version which required Android 5+.
I found an archived version of the Google Home app on apkmirror and used it to install that supported version using the Adroid Debug Bridge (ADB) from the Android SDK (see: https://www.apkmirror.com/apk/google-inc/google-home/google-home-2-14-50-11-release/google-home-2-14-50-11-3-android-apk-download/download/ )

The basic ADB command is: adb install [PackageName].apk
This assumes you have your smartphone/tablet connected to your computer via a USB connection and the the smartphone/tablet has USB Debug mode enabled to allow a 'push' install from the computer to the device you want to install the app to.
Answer: If you're a rooted user, you can simply change your android version by editing the /system/build.prop , for this find the following line and edit the way you want:
ro.build.version.release=xx

where xx is the android version you want, after that restart your device.
If you're not rooted user you can modify the Androidmanifest.xml file of the apk and modify the minSdkVersion, there's alot of tools that do this.


AppleScript (or other code?) to change iTunes library depending on disk presence

Question: I have my large music library on my external drive, and a more portable sized library on my internal drive. What I really would like to have is an app that checks for the presence of my external drive and then proceeds to launch iTunes with the correct library.
I am aware of the question here, and while that may be pretty close to what I want to do, I do not know enough Applescript to make it happen. There is also this neat script , but it gives me this error: "Finder got an error: ln: /Users/Matt/Music/: Permission denied" and I don't know how to change permissions for that to work. Plus I don't need it to function for every user, although it isn't a big deal.
There is another guy who got his situation resolved with ControPlane, which I currently use for other purposes. I could not figure out a sensible way to run the script only when I launch iTunes and still have it switch my Network prefs for when I'm at work or home.
Would changing one of those Applescripts work best? If so, how can I make it work? Or could we have ControlPlane run a script changing which library iTunes will open, depending on if my drive is connected or not? (While still maintaining my correct network settings)...
Any advice would be greatly appreciated. Thanks guys!
Answer: Another solution you might try is using Keyboard Maestro. You would be able to build a trigger for iTunes, so that launching the application would run a script, and that script could choose the appropriate library based on the presence of the external drive.


Why do I breathe out of BOTH nostrils?

Question: After reading the question why do I only breathe out of one nostril I realized that breathing out of both isn't common. I have always breathed out of both, and when I get a stuffy nose, or a runny nose, it's on both sides. If only one side is stuffed, I'll just lay on my side a bit to even it out until I can breathe out of both again. I've always though that was totally normal! What does it mean that my autonomous nervous system is not alternating my breathing?
Comment: If you're concerned, talk to a doctor - we can't give you medical advice here. Speaking biologically though, as you can read on the page you linked, we don't really know whether the nasal cycle serves any purpose. The only explanation I've heard is to reduce desensitisation of the olfactory sensors from overstimulation (basically giving each side of the nose alternating breaks). Assuming that, the only effect of a genetic variant that doesn't have a nasal cycle would be a weaker sense of smell.
Comment: @Armatus The nasal cycle may also be an artifact of the way our autonomic nervous systems works in bilaterally symmetric animals. Another hypothesis is nasal defense. I included some links in [my answer](http://biology.stackexchange.com/a/21219/8517) to the one-nostril question, if you're interested. :)
Answer: The odds are that you're noticing the equality of patent nostrils in the middle of a changeover, when both are equally patent. Also, the shape of your nose may be permitting the congested side to still be fairly patent. Your nose is doing what it's supposed to be doing (and everybody suffers bilateral congestion during colds, allergies, etc.) If it were not, you would be plagued by dry, painful and bleeding nares (um... are you?)

Why do I breathe out of BOTH nostrils?


How to make Scrum of Scrums meetings more productive?

Question: At my job, we're having a Scrum of Scrums meeting where all the Scrum Masters get together. This meeting is turning into a boring meeting where everyone gives their status update. I'm trying to make the Scrum of Scrums meeting more proactive, where Scrum Masters will be more involved with other Scrum Masters, and where it is more of a time for Scrum Masters to call out dependencies on other teams and agree upon a solution to remove those dependencies.
Comment: What is the purpose of the meeting?  Is it a team co-ordination meeting to identify things one team might do that will impact another or is it a Scrum Master community of practice to advance the state of the art within the Scrum Master group?
Comment: I was going to offer a bounty on this question because I think it is a widely-applicable question, but has received too little attention. However, there's a PMSE [bounty bug](http://meta.pm.stackexchange.com/q/431/4271), so perhaps a user with rep to burn would like to bounty it to see if we can't attract more attention to this great question.
Comment: Hi @CodeGnome, before offering a bounty, I suggest editing the question to make it clear what's missing and what you're hoping to get as answers, since there are 3 great answers already.... In this particular case, if your edits would substantially change the question, it might even be better to post a *new* question if what you're looking for isn't covered in this one. Hope this helps! Good luck! :)
Answer: Our team co-ordination meeting was getting really stale too so we did a few things to try and improve it which seem to have worked pretty well.

We focus our team co-ordination meeting around a board, similar to
team standups.
Each team has a swim lane and puts a card up stating what they're
working on now and next.  This gives teams an opportunity to question
each other when there is a dependency between them which is our
primary reason for running the session.
We track actions that have been taken by teams on the board and
review them each week.
We have a process in place for escalating to the senior team.
Anyone can come but a senior developer from each team must be
present.  We introduced this because we were finding other team
members lacked the technical understanding of our platform to really
identify where teams were going to cause each other problem.
We keep cards for the previous 4 weeks on the board to provide a
quick reference for what people have been working on.

Above is an example of our board.
Answer: I suggests to change how the Scrum of Scrum meeting is facilitated. Instead of talking about usual stuff and about the three questions, I would focus only on the following key points and have a discussion about them:

Which team is going to deliver today: Here other teams shall know that something new (package, code etc.) will arrive at their desk.
Is there a mentionable change in the burn-down charts: Another indicator that a team will receive something earlier or later than expected.
Is there any change in the backlog: Again, an important global change.

The idea is to focus only on those things which affect other teams. In order to do it effectively, the teams shall discuss what to bring to the Scrum of Scrum meetings. It shouldn't be something the ScrumMaster finds out. If the team has nothing to say, that the SM shall say that there is nothing to add to the meeting. If it happens on multiple occasions, then something is going on at the team level, which is worth checking out.
Additionally, there is something else which is worth checking out. How come that Agile people turn their own meeting into a status meeting? Don't get me wrong, our ScrumMasters do it all the time, but you may be able to find a good reason and fix it. We still don't know why they do it, and neither do they.
Here I blogged about some daily stand-up variants, you may find something useful there too.
Answer: Scrum-of-Scrums Defined
There are a number of books on scaling Scrum, and I'm sure there are other definitions out there, but I'm going to share my personal definition with you.

A scrum-of-scrums standup is a dependency-coordination meeting between scrum teams.

Ideally, a scrum-of-scrums should have a separate Scrum Master who isn't wearing the Scrum Master hat for another team. That person should be the referee who blows the whistle whenever the meeting begins to slide off the agile track.
Human Kanbans
Think of each Scrum Master attending the scrum-of-scrums standup as a human kanban. That person's job is to:

Notify the other teams that a value-stream work element is ready to be pulled from that Scrum Master's team.
Alert the other other teams that some work element is occupying an inter-team work-in-progress slot, and is stuck inside the Scrum Master's team because a defect or process bottleneck has been discovered.

In other words, this should be a short coordination and commitment meeting between Scrum Masters, rather than a status pull, review, or retrospective. However, without a designated Scrum Master to act as a process referee, and without a strong organizational commitment to inspect-and-adapt at the scrum-of-scrums level, meetings like the one described in the question are all too common.
Answer: I concur with most of the suggestions above if you are doing a Scrum Master scrum of scrums.  I would ask yourself what the purpose of that meeting is.  If it is just technical coordination of immediate activities, then focus around that and the scrum masters (or senior developer) should be able to handle them.
If the focus is to keep the teams coordinated beyond just technical dependencies, I might suggest a scrum of product owners (assuming that you have product owner/business analysts or similar on each team) as well or even instead.  These folks are responsible for maintaining the overall vision and ensuring that business need is being met instead of just looking at the software.  Particularly as you move from being software focused to solution focused, the broader vision will often bring into focus areas that a team needs to be concerned about beyond just doing coding.
Either way, I would use the scrum of scrums as more than just immediate coordination between teams and a regular meeting to look at overall picture of the product (or sprint or release).
Answer: Scrum emphasizes not only self-organizing teams but also cross-functional team collaboration for better performance. Known as Scrum of Scrums, this practice is important for large, multidimensional projects which require  cross departments and teams to work in close collaboration so that the overall performance is as effective as in small projects involving smaller teams.  The key to this scalable element is the Scrum of Scrums, known in traditional parlance as "program management."
Scrum of Scrums is a very good practice, but its success depends on two key factors – effective coordination and an efficient program manager. If either or both these conditions are not fulfilled, Scrum of Scrums proves to be the Waterloo of the entire project.
In projects involving a single team of few people, Scrum Master is the guide and the mentor who steers the team in the right direction. However, with multiple teams working together on the same project, there has to be a manager who can coordinate effectively across the teams. In such a scenario, each team has its own Scrum Master who in turn coordinates with the Scrum Masters of the other teams under the guidance and supervision of an overall program manager, known as Agile Program Manager.
Source:  http://scrum-master.info


How to avoid bug leakage in the Software Product

Question: Can you anyone explain the What is Bug leakage with example and how to avoid bug leakage in software product development?
Comment: "Bug leakage" is the same as "Defect Leakage". A quick Google search will define those terms and provide examples.
Answer: Bug Leakage is defined as:

Software bugs/defects that are discovered in the current phase of product that was supposed to be found in an earlier phase of the product.

An example of this would be a customer reports seeing an issue on your product in a production environment after your team tests and deploys it from a staging/testing environment.
Although there are a wide variety of fixes for bug/defect leakage, I would start by looking into your companies current approach to testing. Here are some common issues I have seen while working in my career.

Lack of product knowledge. (Alleviate this issue with training your testers on the products that they are testing)
Process review for test cases. (Ensure that test case reviews are happening. Meaning that another person who didn't create the test cases reviews them, and ensures they are of good quality)
Quality of testing data in your staging/testing environment. (Always strive to have an environment where you have comparable data to a production environment, work with team-members of your company to gain access to what you need)
Tests are limited to "Happy Path" testing. (Review your test cases to ensure there are some "Edge Case" scenarios that are covered in testing. Another option that has been extremely helpful in the past for me is by adding a few hours of exploratory/ad-hoc testing to a release cycle)
Some testers might just be "Checking" the requirements and not "Testing" them. (Reach out to your testers and make sure they know you are not just looking for a spot check of requirements, make sure they are digging deeper into the tests to expose flaws. Test cases are a good blue print for the tester, but they miss a lot of details that should be implied with quailty QA testing)
Comment: 6. Testers might not be receiving the resources (time, instructions, equipment) they need to do a good job in finding the issues.
Comment: 7. The product my be so flawed/buggy that it's not possible to uncover all the underlying bugs. (Bugs often block other bugs).
Answer: Bug leakage: When a bug is found by the end users or customer, and missed by the QA team while testing the software.
**For example:-**QA team tested the software for a .XX version release on their QA or staging environment.
After the release on production, if any valid issue has been found by customer then such an issue termed as Bug Leakage.
Below are the few points need to be followed by QA of any software testing company in order to avoid bug leakage issues:-

QA Manager/Lead's/BA's should actively participate, discuss and bring out scenarios that happens in live environment
Make sure that test case should covers every modules of your software
Proper review of test cases from the lead and monitoring the test execution cycle
Change in hands means if in any build cycle Engineer A executing then in another cycle allot to another QA engineer.
Try to complete the test case execution before the release so QA have time to run adhoc test on the product.
Answer: Other answers have defined bug leakage, but the avoid answers seem to be very process specific. They look like generally good ideas, but every company and product is different. Answers like test more and test everything seem unsatisfactory.
I would suggest for every bug that leaked you execute a root-cause analyses. Find the core reason and fix that with whatever is needed to fix that. Don't create extra quality gates in your process too fix symptoms. That will just slow you down and probably waste a lot of resources.
Answer: To ensure that defect leakage is avoided and not persistent in the software product, as well as to validate the product's quality, it is essential for software developers & testers to use several ways to prevent it. This allows them to evade issues in the software development cycle as well as saves their combined testing and development efforts.
Hence, the ways to avoid bug leakage in the software product are:
•   Pick a precise area & perform a comprehensive analysis and testing
•   Scrutinize for sensitive areas and content
•   Check out the exact components that are prone to high-bug leakage
•   Consider a rewrite if things are beyond doubt
•   Perform rigorous testing on tiniest elements
•   Have a closer look at the complete system
•   Test the product in real-world like setting
To find defects and to avoid bug leakage is though crucial for effective and proper software development. It can be damaging and terrible if found in abundance or at the wrong time.
It is the responsibility of

Quality Assurance (QA)

and

software tester team

to uncover all the bugs, defects, flaws, and more from a system at the suitable time, as it will help them build an efficient application or software of top-quality, functionality, performance, and more.
Moreover, the lower the value of bug leakage in software testing, the better is the quality.


Can I copy id_dsa keys?

Question: I generated id_dsa key (ssh key) for my client, and then copied them over to authorized_keys.
And it works.
Is it possible to copy these Keys to another user account, so I don't have to re-create these keys?
Answer: short answer is yes. there's nothing about these keys that are special. just copy the files to the proper location and set the permissions (user:group and ugo) and it should work.
Answer: Longer answer is "think really hard about whether you want to do it." If one user gets compromised, you'll need to provide keys for all of them. Further, if the users know they are sharing keys, they will be able to impersonate each other.

Can I copy id_dsa keys?


Does the lower mass of Uranus suggest it swapped position with Neptune?

Question: As Uranus is less massive than Neptune, would this be evidence that it was formed further away from the sun than Neptune, and later it swaps orbit with Neptune to move closer to sun?
Answer: The Nice model of solar system evolution proposes that both Uranus and Neptune migrated outward from their original orbits due to numerous encounters with planetesimals,
stimulated by a temporary 2:1 resonance between Jupiter and Saturn.
Simulations going back billions of years can put either Uranus or Neptune initially closer to the Sun.
Desch 2007, assuming that the Nice model is correct, argues for a particular density profile of the protoplanetary disk and notes that a closer proto-Neptune fits that profile better.
Some solar system scientists have problems with the Desch model, but Uranus's smaller mass is consistent with it.
Answer: No. The difference in mass is less than 20%, and for astronomers that counts as "basically the same" (for the masses, check wikipedia).
Your question implies that more massive planets should form closer to their star. However, there is as yet no definitive theory on the formation of planetary systems - that might come with the next generation of telescopes, (E-ELT, TMT, GMT, JWST) as they will allow us both to study more than one planetary system and better observe the early stages of planet formation.


Intuition behind using complementary CDF to compute expectation for nonnegative random variables

Question: I've read the proof for why $\int_0^\infty P(X >x)dx=E[X]$ for nonnegative random variables (located here) and understand its mechanics, but I'm having trouble understanding the intuition behind this formula or why it should be the case at all. Does anyone have any insight on this? I bet I'm missing something obvious.
Comment: This post itself could have served as a "mother post" to duplicates. The current choice of [mother post](https://math.stackexchange.com/questions/843845) has existing duplicate-links which this post doesn't. Please see the meta post on [(abstract) duplicates](https://math.meta.stackexchange.com/a/29382/356647).
Answer: For the discrete case, and if $X$ is nonnegative, $E[X] = \sum_{x=0}^\infty x P(X = x)$.  That means we're adding up $P(X = 0)$ zero times, $P(X = 1)$ once, $P(X = 2)$ twice, etc.  This can be represented in array form, where we're adding column-by-column:
$$\begin{matrix} P(X=1) & P(X = 2) & P(X = 3) & P(X = 4) & P(X = 5) & \cdots \\ & P(X = 2) & P(X = 3) & P(X = 4) & P(X = 5) & \cdots \\ & & P(X = 3) & P(X = 4) & P(X = 5) & \cdots \\ & & & P(X = 4) & P(X = 5) & \cdots \\ & &  &  & P(X = 5) & \cdots\end{matrix}.$$
We could also add up these numbers row-by-row, though, and get the same result.  The first row has everything but $P(X = 0)$ and so sums to $P(X > 0)$.  The second row has everything but $P(X =0)$ and $P(X = 1)$ and so sums to $P(X > 1)$.  In general, the sum of row $x+1$ is $P(X > x)$, and so adding the numbers row-by-row gives us $\sum_{x = 0}^{\infty} P(X > x)$, which thus must also be equal to $\sum_{x=0}^\infty x P(X = x) = E[X].$
The continuous case is analogous.
In general, switching the order of summation (as in the proof the OP links to) can always be interpreted as adding row-by-row vs. column-by-column.
Comment: This answer is beautiful and illustrative (+1)!!
Answer: A hint and a proof.
Hint: if $X=x$ with full probability, the integral is the integral of $1$ on $(0,x)$, hence the LHS and the RHS are both $x$.
Proof: apply (Tonelli-)Fubini to the function $(\omega,x)\mapsto\mathbf 1_{X(\omega)>x}$ and to the sigma-finite measure $P\otimes\mathrm{Leb}$ on $\Omega\times\mathbb R_+$. One gets
$$
\int_\Omega\int_{\mathbb R_+}\mathbf 1_{X(\omega)>x}\mathrm dx\mathrm dP(\omega)=\int_\Omega\int_0^{X(\omega)}\mathrm dx\mathrm dP(\omega)=\int_\Omega X(\omega)\mathrm dP(\omega)=E(X),
$$
while, using the shorthand $A_x=\{\omega\in\Omega\mid X(\omega)>x\}$,
$$
\int_{\mathbb R_+}\int_\Omega\mathbf 1_{X(\omega)>x}\mathrm dP(\omega)\mathrm dx=\int_{\mathbb R_+}\int_\Omega\mathbf 1_{\omega\in A_x}\mathrm dP(\omega)\mathrm dx=\int_{\mathbb R_+}P(A_x)\mathrm dx=\int_{\mathbb R_+}P(X>x)\mathrm dx.
$$
Comment: "A hint and a proof" but the OP asks about intuition (how intuitive can the sigma-finite measure on the tensor product of $P$ and Leb be??). The math in this answer is unnecessarily complex, compared to the question: hence the downvote from me.
Comment: I spent much time but I couldn't prove that the bivariable function $(\omega,t)\mapsto \mathbf 1_{\{(\omega,t)\,|\,X(\omega)>t\}}$ is a measurable function respect to $\mathcal{F}\times\mathcal{B}$. It's just obvious that it's measurable when one of the variables is fixed.
Comment: @Math1000 $\mathcal F\times\mathcal B(E)$ to be replaced by $(P\otimes\mathrm{Leb})(E)$.
Comment: @Math1000, thank you, but how did you find $E$ is $\mathcal{F}\times\mathcal B-$measurable before writing $P\times\lambda(E)$? Indeed, we only need its measurablity.
Comment: @FardadPouran Let $E=\{(\omega,t)\in\Omega\times\mathbb R_+ :X(\omega)>t\}$ and define the $\omega$- and $t$- sections of $E$ by
\begin{align}
E_\omega &= \{t\in\mathbb R^+ : (\omega,t)\in E\}\\
E^t &= \{\omega\in \Omega : (\omega,t)\in E\}.
\end{align}
The monotone class lemma implies that the maps $\omega\mapsto \lambda(E_\omega)$ and $t\mapsto \mathbb P(E^t)$ are $\mathcal F$- and $\mathcal B$- measurable, respectively.
Comment: @Did Thanks for pointing out the typo.
$$\mathbb P\times\lambda(E)  = \int_\Omega \lambda(E_\omega)\,\mathsf d\mathbb P(\omega) = \int_{\mathbb R_+} \mathbb P(E^t)\,\mathsf d\lambda(t).$$
So the map $(\omega,t)\mapsto \mathsf 1_E$ is indeed $\mathcal F\otimes\mathcal B$-measurable.
Answer: Since the intuition behind the result is requested, let us consider a simple case of a discrete non-negative random variable taking on the three values $x_0 = 0$, $x_1$, and $x_2$ with probabilities $p_0$, $p_1$, and $p_2$.  The cumulative distribution function (CDF) $F(x)$ is thus a staircase function
$$F(x) = \begin{cases}
0, & x < 0, \\
p_0, & 0 \leq x < x_1,\\
p_0 + p_1, & x_1 \leq x < x_2,\\
1, & x \geq x_2,
\end{cases}$$
with jumps of $p_0$, $p_1$, and $p_2$ at $0$, $x_1$, and $x_2$ respectively.
Note also that
$$
E[X]= \sum_{i=1}^3 p_ix_i = p_1x_1 + p_2x_2.
$$
Now, notice that
$$\int_0^\infty P\{X > x\}\mathrm dx = \int_0^\infty [1 - F(x)]\mathrm dx$$
is the area of the region bounded by the curve $F(x)$, the vertical axis,
and the line at height 1 above the horizontal axis.  Standard
Riemann integration techniques say that
we should divide the region into narrow vertical strips, compute the area of each,
take the sum, take limits etc.  In our example, of course, all this can be bypassed
since the region in question is the union of two adjoining non-overlapping rectangles:
one of base $x_1$ and
height $(1-p_0)$, and the other of base $x_2 - x_1$, and height $(1-p_0-p_1)$.  BUT, suppose we divide the region under consideration into two different adjoining
non-overlapping rectangles with the second lying above the first.
The first rectangle has base $x_1$ and height $p_1$, while the second
(lying above the first) has broader base
$x_2$ and height $p_2$.  The total area that we seek is easily seen to be
$p_1x_1 + p_2x_2 = E[X]$.
Thus, for a non-negative random variable, $E[X]$ can be interpreted as the area
of the region lying above its CDF $F(x)$ and below the line at height 1 to the
right of the origin.  The standard formula
$$E[X] = \int_0^\infty x\mathrm dF(x)$$
can be thought of as computing this area by dividing it into thin horizontal
strips of length $x$ and height $dF(x)$, while
$$\int_0^\infty P\{X > x\}\mathrm dx = \int_0^\infty [1 - F(x)]\mathrm dx$$
(in the Riemann integral sense) can be thought of as computing the area by
dividing it into thin vertical strips.
More generally, if $X$ takes on both positive and negative values,
$$E[X] = \int_0^\infty [1 - F(x)]\mathrm dx - \int_{-\infty}^0 F(x) \mathrm dx$$
with similar interpretations.
Answer: Perhaps by considering this question with a concrete physical example,
it will provide some intuition.
Consider a beam of length $L = 10$ (you can pick your favorite units)
attached to a wall. Now, at positions $1, 2, \ldots, 9$
hang weights $w_1,w_2,\ldots,w_9$. For simplicity, let's assume
$\sum_{n=1}^9 w_n = 1$.
Then the center of mass of the beam is $c = \sum_{n=1}^9 n
w_n$. below is an example picture, with the weights in blue (heights
proportional to weight) and the center of mass in red.

In a probabilistic setting, our weights correspond to probabilities
and $c = \mathbb E X$ where $X$ takes on the values $1,2,\ldots,9$
with probabilities $w_1,w_2,\ldots,w_9$, respectively.
Now, to explain how $c = \mathbb E X = \sum_{n=0}^9 \mathbb P(X > n) = \sum_{n = 0}^9
\sum_{k=n+1}^9 w_k$ comes about, expanding out the latter sum we have
$$
c = (w_1 + \cdots + w_9) + (w_2 + \cdots + w_9) + \cdots + (w_9) \>,
$$
so, $w_1$ appears once, $w_2$ appears twice, $w_3$ appears three
times, etc. Hence $c = \sum_{n=1}^9 n w_n$.
In terms of the beam, we can think of the expression $\sum_{n=0}^9 \mathbb P(X
> n)$ in the following way. Standing at zero, look out to the right
and count up all the weights in front of you. Now, move one step to
the right and repeat this process, adding the result to your initial
sum. Continue this process until you get out to position 9, at which
point there are no more weights in front of you.
The resulting sum is the center of mass, or, in probabilistic terms,
the expectation $\mathbb E X$.
Extending this intuition to discrete random variables taking on non-integer values is straightforward. The extension to continuous variables is also not difficult.


How can I add vertices to intersection of two edges?

Question: I need to put a point at the intersection of two edges. Below is a picture with red circles around where I need points to be placed.
Comment: related: http://blender.stackexchange.com/questions/805/is-there-any-good-way-to-snap-to-intersection

Do you just want to add a vert there, or do you want to merge the existing verts? (see http://blender.stackexchange.com/questions/1759/snap-individual-vertex-of-the-selection-to-closest-vertex/1760#1760)
Comment: Either way. If it just adds the vert there, I can manually merge it.
Comment: CTRL + R Sometimes finds those intersections
Answer: With Blender 2.8+ you can use the Auto Merge Tool to insert a vertex between intersecting edges.

Just enable the option Auto Merge and Split Edges & Faces in the Tool Shelf, then select a vertex and move it. Upon placing it down the tool will create vertices between the connected edges and the edges intersecting them.
If you don't want to move any vertices just select the intersecting edges or their vertices and press GEnter
Comment: This is most definitely the best solution now! Thank you for making me aware of it. If you want to make sure to not move it at all, **G** **Z** **0** **Enter** would be the safest way to avoid moving it even a pixel.
Answer: If all you really want is to add a vertex at the position of intersection, then something like this script would work: (this even adds the vertex at the  projected intersection of two lines, or the closest point if they never intersect)
import bmesh
import bpy
from mathutils import geometry

def add_vertex_to_intersection():

    obj = bpy.context.object
    me = obj.data
    bm = bmesh.from_edit_mesh(me)

    edges = [e for e in bm.edges if e.select]

    if len(edges) == 2:
        [[v1, v2], [v3, v4]] = [[v.co for v in e.verts] for e in edges]

        iv = geometry.intersect_line_line(v1, v2, v3, v4)
        iv = (iv[0] + iv[1]) / 2
        bm.verts.new(iv)
        bmesh.update_edit_mesh(me)

add_vertex_to_intersection()

this does not attach the vertex to any edges/faces. Here it is packaged as an addon accessible from: W > Place vertex at intersection

This is now part of mesh_tinyCAD
A while back I added this feature to mesh_tinyCAD, and called it (Vertex to Intersection) V2X. I use it to add guide-vertices to intersections and it is less potentially destructive than the XALL or VTX operations.
Comment: You make it looks easy.
Answer: I found tinyCAD addon the most helpful solution for this problem. It can be downloaded here:
https://github.com/zeffii/Blender_CAD_utils
You can install several ways but the easiest is to download the zip linked in the readme and use the Install from File option in UserPreferences > Addons. Then you can enable it as usual.
To use it, just select intersecting edges, press W and select TinyCAD > TinyCAD XALL
Comment: Great find. This is the question that originally brought me to this site, and this addon is the only solution I've really liked so far.
Comment: Unfortunately this also removes any faces connected to the edges.
Answer: To expand on Haunt_house's answer, to place a vertex at the intersection you can use the Dynamic spacebar addon
This is include with development builds of blender by default, but you will still have to enable it in the User preferences:

If you are using a release version, you can get it here
Press Space> Snap Cursor menu > Cursor to edge intersection:

This snaps the 3D cursor the the intersection between the selected edges.
Now you can add a new mesh (press ShiftA while still in edit mode) and then press ShiftS> Selection to cursor:

Then select the vertices you want to merge with one of the ones on the intersection selected last and press AltM> At last:

Alternate Workflows
For something like this, You might be better off with a different workflow:
Array modifier
You could use the Array modifier with an object offset, see this answer

Note that in the above image, the plane object as been rotated -120 degrees in object mode.
(This would be similar to Haunt_house's solution of using different objects)
Primitives
You might be able to use a primitive to get the desired geometry, Add a circle and set the vertices to 3 in the Redo menu or the F6 menu:

Extrude upwards, select all, then press AltE> Individual faces:

Delete the top vertices:
Comment: I would suggest you remove the *Alternate Workflows* section because they are specific only to the model I showed in the example and not helpful to anyone else visiting this question.
Answer: There are several approaches. The Dynamic Spacebar Addon answer might be one of them.
Here are some other:

Instead of creating the three parts in Edit Mode, create them in Object Mode as linked copies with AltD and rotate them. If you now go into editmode, you can adjust the length by using G and restraining to a local axis by pressing X, Y, or Z twice. With enough zoom you can adjust the verts to meet and then merge them with AltM or the Magnet Tool. Remove Doubles should work too.
You can use the Knife. Select all verts, zoom in a lot and cut the edges with ShiftK (shift to cut all edges) where they intersect. Then clean up.
You can select the verts of the upper vertical part, and move them up until they meet the side part's edges. Then use the cursor as pivot point with Dot. Copy one of them and rotate it 120 degrees around the cursor to get the third intersection point.
You can use the Knife Project Tool to cut them
You can use a three sided cylinder and extrude it outward. While in Face Select mode, select the three sides and use Mesh>>Extrude>>Individual Faces (if you have cubes instead of planes in your example). Sometimes reversing the workflow is a good idea.
You can use Vertex slide. Select the vertices and press G twice, then slide the vertices along the edges.
If the placement of the parts isn't critical, you can use the Magnet to snap the edges together.
The ordinary Knife Tool has snapping functionality. With everything selected, snap it to both ends of an edge and the intersecting edge will be cut.
Answer: So, I had to play with this until I solved it in the basic mathematical sense. So, here's a solution that will work for a pair of edges that really intersect, and it will also edd a vertex at the intersection point.
To activate:

Open a text editor window and create a new text file.
Paste the code from below there.
Select the intersecting edges.
Press Run Script.

Here's the code:
import bpy, bmesh
from mathutils import Vector

globCo = lambda co, o: o.matrix_world * co

def find_intersection( edges, o ):
    # Calculate global locations of edge verts
    p1, p2 = [ globCo( v.co, o ) for v in edges[0].verts ]
    p3, p4 = [ globCo( v.co, o ) for v in edges[1].verts ]

    v1 = p2 - p1 # Edge 1 line vector
    v2 = p4 - p3 # Edge 2 line vector

    # Calcualte intersection
    # Based on paramteric line equation: (x,y,z) = p0 + t * lineVec
    numer = v2.y * ( p3.x - p1.x ) + v2.x * ( p1.y - p3.y )
    denom = v1.x * v2.y - v1.y * v2.x
    t1    = numer / denom

    co = Vector( [ getattr( p1, i ) + t1 * getattr( v1, i ) for i in 'xyz' ] )

    bpy.context.scene.cursor_location = co

    return co

o  = bpy.context.object
if o.mode == 'EDIT':
    bm    = bmesh.from_edit_mesh( o.data )
    edges = [ e for e in bm.edges if e.select ]

    if len( edges ) == 2:
        co = find_intersection( edges, o )

        # Split edges and add new vert to newly created edges
        for e in edges:
            p1, p2 = [ globCo( v.co, o ) for v in e.verts ]
            fac = ( co - p1 ).length / ( p2 - p1 ).length
            bmesh.utils.edge_split( e, e.verts[0], fac )

# Remove doubles
bpy.ops.mesh.select_mode( type = 'VERT' )
bpy.ops.mesh.select_all( action = 'SELECT' )
bpy.ops.mesh.remove_doubles()
bpy.ops.mesh.select_all( action = 'DESELECT' )

Comment: I'd like to point out that matrix multiplications now use @ instead of *.
"o: o.matrix_world * co" would become "o: o.matrix_world @ co"
Answer: Just a brief contribution, no-code solution and perfect precision:

Select the edges you want to intersect
Extrude them out to make faces (direction doesn't matter much)
Select the faces, Ctrl + F, Intersect (Knife)
Expand the context menu that appears bottom-left (subtle)
Under the Source drop-down menu, select Self Intersect
Select all, merge by distance to merge vertices
Delete the extra vertices which made up the temporary faces, and you're done!

Enjoy your new intersection.
Answer: Another way that I find easier is to just use the knife tool K. Press K then left click near the intersection, draw the line over the intersection and left click again, then hit enter. This creates three new vertices, one of which is at the intersection. Delete the others and fill in any faces that get removed and you are done.
Answer: Quick & Dirty solution
This I use and should work for you in any case (no cutting) without creating unnecessary geometry in the end. This method is manual and might not be fast for cases with multiple intersections in different locations.

Fill in edges from verticies (select two vertices, F to fill edge)
Extrude (E) half-length edge from any original vertex (in corners)
(overlay any existing edge with one new while having snapping set to "Edge Center")

Delete the half-length edge (X or DEL) as in "Only faces & vertices" (The vertex of the intersection will be preserved)


Is DES slow in hardware or only in software?

Question: I have been reading that DES is slow.  Is it only slow in software or slow overall?  Also, as far as Triple DES being slow is concerned, is double AES with two 128 bit keys slower than single AES with a 256 bit key?
Comment: Note that bitsliced DES isn't that slow in software, but you can only use it if you can process multiple blocks in parallel. This is the case for ECB, CTR and CBC decryption, but not CBC encryption. Similar to [Why is Serpent faster than AES in this benchmark?](http://crypto.stackexchange.com/questions/15091/why-is-serpent-faster-than-aes-in-this-benchmark)
Comment: Note that although 3 DES is slow, there are so many other issues with DES that speed should not be the main reason to avoid it. Weak keys, block size too small, parity bits in keys, the list goes on. That all said, 3DES with 192 (= 168 bit) keys is considered secure as a block cipher.
Answer: DES is slow in software because it was designed back in the early 70's even before the 8086 processor existed, and uses several bit oriented operations that are just not implemented efficiently in a processor with a word oriented instruction set.
Its intended product was ASIC hardware designs, in which DES runs quickly. DES hardware processors are quite common on older network cards intended for use in servers and workstations (I still have LAN card with wire speed TDES hardware). DES was already considered obsolete by the time the technology would have trickled down into consumer grade hardware.
DES becomes even slower when we compare it from a security standpoint against AES. DES in software is probably half the speed of AES, and it is also half the key space. Therefore TDES is used to increase the key space, but now it is 1/6th the speed of AES. AES is also better designed to resist attacks other than brute force.
Double AES with two 128 bit keys requires about 1.5X the processing of AES with a 256-bit key, and at least from a brute force perspective is not as secure. The reason TDES is used instead of double DES is because it requires 3 operations in order to double the key space.
Answer: DES is slow compared to AES including in hardware because

for comparable security we must use 3DES, which triples the number of rounds per block, to 48 for 3DES versus 10, 12, or 14 for AES;
DES's block size is 64 bits, half of AES's 128 bit; so when encrypting a sizable block of data, 3DES does more rounds that AES by a factor of 96/10, 96/12, or 96/14;
these is no (or little) hardware support for DES in modern CPUs, when there is for AES in increasingly many CPUs, including most targeting servers; hence hardware DES is offloaded to a distant IC, when AES is often in-core;
DES is often used in CBC mode which does not allow parallelization and in-advance processing during encryption, when AES is often used in CTR mode which does.

However when we compare DPA-protected implementations as used in Smart Cards, there is not so much of a difference, and it is tends to be buried among other delays.

Double AES with two 128 bit keys would be significantly slower than single AES with a 256 bit key (20 rounds versus 14). Also double AES-128 would theoretically be vulnerable to a Meet-in-the-Middle attack, when AES-256 is not.
Comment: You might want to expand the blocksize point.
Answer: The Digital Encryption Standard is the description of an algorithm originally requiring a hardware implementation to be compliant.
The Initial Permutation when implemented with an 8 bit interface is 8 wires, the Inverse Permutation swaps the L and R block by swapping odd and even elements on the 8 bit interface.
The issue with performance in software comes from not having instructions to do things that we can describe in hardware that have no performance penalty (permutations).
Intel had an i8048 based implementation using embedded programming and couldn't keep up with a 300 baud MODEM.
At the same time Fairchild Federal had a bipolar CMOS chipset that was used in encrypting satellite transponders (105 Mbits/sec).  We've seen papers describing high speed hardware implementations in the 5.4 GHz range in the past.
A decade ago Stretch Inc. had a programmable instruction coprocessor that could perform a complete DES round.  There can be separate instructions for things like the Initial Permutation. Unfortunately their reconfigurable hardware isn't big enough for more complex algorithms, DES can be implemented in around 4.7K NAND gate equivalents, a DES round the majority of that).
As noted in the other answers once we accepted the idea of implementing encryption algorithms in higher performance computers we started developing algorithms targeting software implementation. There's also no real security advantage imposed in requiring complexity best left to hardware with the advent of higher performance FPGAs (or ASICs when you need that last factor of 10 speed up).
The restriction to hardware implementations was to control the dissemination of cryptography, which is now pervasive (and systemically attacked in different ways such as through key exchange weaknesses or secret subpoenas).
The original UNIX libcrypt had a DES implementation that could be initialized with a null salt (it was used for password hashing) and with some input and output alignment be compatible with the DES standard, executing 16 rounds once (instead of 25 DES interations). Essentially the cat had already been let out of the bottle (mixing metaphors).


How much protein should I eat on off-days?

Question: I'm aware that eating protein is important on the day of your weight lifting session. The most important time to eat protein is right after the session. But I've never heard advice on when to eat and how much protein to eat on off-days. How quickly does your muscle's need for protein diminish over time? My guess is that the 1-2 hours right after the weight lifting are crucial. Then the night of sleep uses moderate amounts. Then on the next day (the off day), you need minimal amounts of protein. Is this correct?
Comment: interesting... I wanna know the truth too... :( some people say the best time to eat more protein is on off-days 'cause it's when your muscles grow.
Comment: also read: http://fitness.stackexchange.com/a/611/692
Answer: The idea that the most apt time to eat protein is right after a training session has no scientific validity. It's a great marketing claim used by shake manufacturers to impress upon you the need to buy their convenience powders. Your body does not suddenly start building muscle immediately after a workout. Protein metabolism is a very well-studied process, and it happens over a period of days after your training. In fact, your body goes through a diurnal cycle that involves period of net anabolic and catabolic activity.
Therefore, the importance of protein is not the timing of after a workout or even on "off days" but on average over a period. I wouldn't complicate your nutrition trying to time it specially on on or off days because you don't really know when the "on day" is for your recovery. So, you need a steady stream of quality protein every day, and there is no need to spike it at certain periods. Excess protein in a short period of time simply gets converted to sugars and burned as fats, albeit through a highly inefficient metabolic pathway that has the net effect of slightly raising your metabolism.
Most of the "requirements" for protein are overblown as well. This is a two-part whammy, one from the supplement industry again trying to sell protein and two from the bodybuilding industry where anabolic steroids do in fact increase the body's capacity to process protein ... unfortunately, it just doesn't work the same way for natural athletes. While it may come as a shocker because all the "advice" forums tell you that you need 1 - 2 grams your body weight in protein per day, the truth is that Dr. Peter Lemon conducted intensive research on the protein requirements of both sedentary and athletic individuals and found that there is no benefit of added protein above 1.5 - 2.0 grams per KILOGRAM of body weight, or about 0.8 grams per pound. The World Health Organization has also researched this ad nauseum in the effort to find the most inexpensive form of usable protein to fight starvation. Most of the "high protein" and "protein after workout" advice comes from paid endorsements and studies funded by the companies promoting the product.
Comment: Protein right after a workout has some scientific backing. Like all exercise science, it's inexact, but: "[A] McMaster University [study] compared the impact of taking a single large dose of whey protein (25 g) immediately after exercise versus taking 10 smaller doses (2.5 g) over a period of time... Researchers found that when men took the 25 grams of whey protein immediately after they exercised, they had a greater increase in muscle protein synthesis than they did when they took the smaller doses." [Source](http://www.emaxhealth.com/1275/how-protein-supplements-athletes-work-new-research)
Comment: His bodybuilding advice came from an era when bodybuilding steroids were rampant (and for a brief period, legal), there is absolutely no comparison to a natural athlete's response. And there is truth to the need for carbs post workout, due to glycogen, that is well supported in scientific literature. Carbs = more important than protein after the workout.
Comment: I'd love to see a quote or a info link here.
Comment: The advice of eating protein after a workout is not only from protein shake manufacturers. I read it in Arnold's *Encyclopedia of Modern Bodybuilding*, which was written before high tech protein shakes became mainstream. He even talks about the recipes for his homemade natural protein shakes because he couldn't find anything from health stores. Arnold says that when the muscles are in a broken state, their need for protein increases. Not only does he recommend eating protein after the workout, but also to eat carbs so that your body does not fallback to protein as an energy source.
Comment: Might also be good to link to your answer here: http://fitness.stackexchange.com/questions/595/at-what-point-during-my-weekly-routine-should-i-be-consuming-extra-protein
Comment: I do remember reading in a few places that you do need to replenish your glycogen immediately after a workout so your muscles don't cannibalize themselves.
Comment: @JoJo did you quote Arnold to debunk what Jeremy was saying or just as a joke?
Comment: Just curious, shouldn't it be 0.8 of LBM instead of total body weight?
Comment: @JoJo Arnold also heavily talks about 'muscle confusion'? Do you believe that too?
Comment: @user2769651 Yes, it's the lean body mass and not your overall weight.
Answer: I've been lifting for years. As a 46 year old 135lb female I was just taking in about 80 grams a day roughly. I did one 32 gram shake after my workout and then just ate whatever. I notice a plateau in my gains and getting weak shortly into my lifts so I added quite abit more protein, I'm up to my body weight in grams and it does seem to be helping already and its only been a couple weeks. My lifts are stronger and I'm seeing slightly more definition. Keep in mind too, its what else you are eating- are you getting enough fruits/veggies? Whole grains? The whole diet needs to be good, can't just gulp down protein supps all day and expect great results. Its worth the effort to pay attention to diet. After all you're working your butt off in the gym, finish it by truly feeding your body what it needs. Just from my own experience I'm thinking your body weight is grams of protein is essential.
Comment: Great answer annie, welcome to fitness.stackexchange.com.
Answer: I think as long as you eat three regular meals and actually worry about pushing yourself during PT eater than worrying about how much protein you need to drink you will quickly realize that the body takes care of itself and doesn't need as much as you think it might to build muscle
And be strong. I'm a firm believer that you can naturally eat healthy and attain muscle mass without being swayed by muscle magazines to buy a ton of powder supplements to spew into your system. A little dedication and tenacity will take you a long way.
Answer: Michael Matthews' quintessential work "Bigger, Leaner, Stronger" suggests between 1g/lb LBW and 1g/lb total weight per day. Jeff Nippard (YouTube fitness celeb) suggests somewhere within 0.75g-1.25g/lb total weight per day. Neither are scientists but both voraciously read scientific articles and have tons of references.
The suggestion above of 0.8g/lb total weight falls within these constraints.
Answer: Jeremy says 0.8 grams of protein is OK for body builders. That would be 185 grams for 231 pounds. That is higher than anything I have ever seen for body builders. Am I reading it incorrectly? There is certainly nothing wrong with timing your carbs for energy and your protein after your workout. Just don't starve yourself of protein at any time, or you will catabolize your own muscles.
Protein powder, purchased at a good price, is competitive with other foods and has less fat than most sources. Lentils and other beans or combination foods, eggs etc. are also inexpensive. Peanut butter and whole wheat bread with a glass of low fat milk is about as good as you can get. Beans and rice form a perfect protein. Brown rice is whole grain and has more fiber and nutrients.
Comment: 0.8g protein per pound of BW is certainly not unheard of. [T-Nation](http://www.t-nation.com/free_online_article/sports_body_training_performance_nutrition/protein_more_muscle_less_guesswork) espouses 1g/lb BW (and at a *minimum*, 0.5g) for bodybuilding. It's common to hear lifters recommend 1g per pound of bodyweight as a *minimum* intake: see [here](http://startingstrength.com/resources/forum/showthread.php?t=14070), and [here](http://startingstrength.com/resources/forum/showthread.php?t=21095). Warning: it's anecdotal, like a lot of lifting advice.
Comment: I believe they are saying .8 grams / lb, not 8 grams / lb.
Answer: Running a protein deficiency leaves the body sluggish.
Typically serious bodybuilders and athletes burn some thousand(s) of calories. The less trained bodybuilders and athletes may do a pretty lazy one-two hour session that burns at least 500 but less than a thousand calories.
Obviously the caloric needs increase. The protein should be replaced too but this is more easily missed. One giant candy bar can make up for the former and recharge the body -- leaving an impression of recovery -- but masking an accrual in protein deficiency.
Eventually, any experienced bodybuilder / athlete will note feeling sluggish, lackadaisical and fatigued. An "off week" is usually taken and, following from enough eating and inactivity, the protein deficiency is eliminated.
The body soon recovers. .8 grams / lb is insufficient for heavy anabolic sports. Dr Peter Lemon's own published slides show significantly increased protein synthesis with 1 grams / lb. Popular anecdote agrees.
Comment: It would help if you tell where you got your numbers from, 8g/lb seem rather extreme, unless you want to sell shakes.
Comment: @Baarn: Bob wrote ".8g/lb", not 8.


Can i store multiple crypto currencies in one wallet?

Question: Is it possible to make a wallet for BTC and store LTC and NMC or other coins in it?
Answer: Coinomi Universal HD Wallet will do exactly what you're looking for.
Coinomi is a very secure and lightweight, universal, open-source HD wallet for Bitcoin and many altcoins. At the moment the supported coins are:

Bitcoin
Dogecoin
Litecoin
Peercoin
Darkcoin
Reddcoin
NuBits
NuShares
Blackcoin
Feathercoin
Rubycoin
Digitalcoin
Cannacoin

with more integrations on the way.
Comment: Coinomi indeed rocks. Still waiting for the Desktop version and the iPhone version, but I think it's the nicest of all of these.
Comment: Not open source anymore.
Answer: I'm not sure if there is a software wallet to do this, but if you want it for cold storage, you can definitely create addresses for almost all the cryptocurrencies from a raw 256 bit private key. This allows you to just securely store the 256 bit key rather than the individual wallet files for multiple cryptocoins.
You can do this by:

Creating a 256 private key of 64 hex (0-9,A-F) digits
Open brainwallet.org and go to the "Generator" tab and select "secret exponent"
Paste your 64 hex digits into the "Secret Exponent" text box.
Select the coin type in the top right corner and the coins private key and address will be shown in the "Private Key" and "Address" areas.

As an example, the 256 bit private key A5F308EB5553464AD377C68D16CDB85F3C8D63CABAC8017BE6D9D9A43F7F0CDF is the following addresses:

BTC (Private): 5K5NXzAa7PE5irZFc9Va6eAN4zPfd2E9MBcrt1ea8j225ix6wpC
BTC (Address): 18S5Czkk3pp8vSwVsS8fD28HLxea6JcVc
LTC (Private): 6vP717i71ogxCET77yHXt2wY2Tx8ppgB7s22bCfbrBLdmZvbD5f
LTC (Address): LKMPLRJapi4sPj96g1RRwE5tVZKviuvMxS
NMC (Private): 74A5i3WERWPrjWmvkHmXhKLdgvR1Re3gGRJTZoRBpoNBk1JL8RM
NMC (Address): MvhoGrVjfRvNfThSmgkhsjB31aMhYnd5qs

Note that this is somewhat insecure as if someone knows the coin private key for one of the addresses, they can directly convert the coin private key back to the raw private key.
Also if you import a private key into a wallet program (eg: bitcoind), be aware that they may send change to new addresses.
Comment: Thanks. Seems like it was not a good idea to try it with multiple currencies in one wallet @.@ Then i must find how i can secure my ufasoft files then it would be working.
Comment: Ufasoft sent me the following on my question about the wallets they use "Private keys shared between all currencies in the Ufasoft Coin. But they have different address string for different currencies. Internally they are the same"
Answer: I don't know a real wallet program that does it, but if you look for a web wallet, VirCurEx might be something.
It's an exchange for different crypto-currencies and so you also have a web wallet for each of them.
Comment: I can understand that you prefer not to. But as I said, there currently is no wallet that can fulfil your needs.
Comment: I dont want to have all my money on a web wallet where it could be stolen all at once when something bad happens. I want to store 3-5 differenct coins but without installing several tools that hold a single coin type. When i find out where the Ufasoft Coin software stores my wallets i could go with it.
Answer: Here's a related question but it only describes UFASoft Coin, which seems like a windows-only desktop application. If you're looking for a cloud solution I've found HolyTransaction to work pretty good.
Answer: Yes and no, the wallet software for each is an independent piece of software built by the community around that single cryptocurrency. It's possible that third party developers have/will develop a multi-currency digital wallet, to date all I have found is http://ufasoft.com/coin/, but I have not used it personally.
Comment: My problem with the ufasoft solution is, that i can not find any information where my coins are really stored. My idea was to use my bitcoin public/private key on another currency.
It would be fine when someone can give me infos on where ufasoft stores its infos.


Is moving the legs forward on pull-ups a bad thing?

Question: I always do my pull-ups with my legs stretched out, no matter the height of the bar. But, the thing that bothers me is that I can't manage to keep my legs in a straight line with my upper body during the workout — they almost always move forward when I lift myself and I feel like that is actually helping me do more pull-ups — it feels like my legs are making the exercise easier on my biceps & back muscles. I have also noticed that bending my legs backwards is making the exercise harder than when my legs are straight. Why is it so?
Comment: Does this answer your question? [Swinging lower body in pull-ups](https://fitness.stackexchange.com/questions/39300/swinging-lower-body-in-pull-ups)
Answer: If you're moving your legs forward while pulling yourself up, it's a way to "cheat" a little bit on the movement.  You're using the momentum of your legs swinging up to help you pull yourself up.
It's not really a problem, since it'll help you get some more pull ups in, but you should try to keep your legs stationary throughout the movement.  (You can keep them up, down, or crossed, but try to keep them steady regardless of where you are during the pull up)
As far as why it feels harder if your legs are kept back, that's likely caused by two things.  First, it may have the opposite effect if you're kicking your legs back.  Second, by keeping your legs behind you, you're stretching your core and using that during the pull up in addition to your other muscles.
For best practice, try to keep the upper part of your legs (down to your knees) straight with your back, and bend your knees slightly so your feet are behind you.  Do not flail/kick your legs and focus on your back/lats/biceps.
Answer: Whether your legs are bent, in an 'L' form (to add abs), or straight down, the importance is consistency...so find your comfort zone and stick with it.
Comment: Welcome to PF SE! Please could you add some evidence to support your answer?
Answer: Assuming you aren't swinging to get extra momentum and doing those asinine "kipping" pull-ups that seem so popular these days, it's really simple physics.
First, in order to be balanced, the pull-up bar needs to be directly over your center of gravity. Think about a pendulum, it will always come to rest directly under its support. Well, the same thing holds when you do a pull-up. As you do a pull-up, you naturally have to lean back as you pull your head over the bar (otherwise you'll bang your head, not recommended), which brings your center of gravity back. To compensate, your legs will naturally float forward to bring you back into balance. If you fight it and force your legs back, you have to apply an additional torque through your core and arms which will naturally make it harder.
The second reason is that when your feet go forward, your upper body will lean back slightly, putting your lats and traps it a more advantageous position, allowing more of your muscles to be used while pulling you up. Think the difference between a lat pulldown and a seated row; by having a slight lean you are slightly closer to a seated row-type motion.


Are reviewers more harsh or lenient at different times of the day?

Question: I tend to see that reviewers are more lenient at certain times of the day. For example, I see many (very) minor suggested edits approved at around 1pm UTC. Has your experience also seen this sort of thing occuring, and are there any statistics that show the ratio of positive to negative reviews?
Comment: Is that data available in SEDE maybe?
Comment: @Adel: I was initially thinking of this in the context of reviews which is most obvious from what I see, though this could apply to any part of the system.
Comment: 1pm is about when the college kids wake up, and it's mostly them who badge-game.
Comment: 1PM UTC. That sounds like the time I'm usually not home.
Comment: Why are we limiting the discussion to reviewers? What about downvotes and general votes. or maybe you meant that. anyway nice question
Comment: Wouldn't this be something scary to accurately measure though? Nightime-india is daytime-USA. We'd have to split those groups I think. But intuitively, people ae crotchety at EOD - that much is clear. [Judges are lenient after lunch, for eg](https://www.google.com/search?q=judges+lenient+after+lunch&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a)
Answer: Here's a statistic, it plots the ratio of questions vs answers throughout the day, broken down by UTC hour and annotated by locale:

It is a bit out of whack, horizontal axis is off by an hour, screwed up the title and Americas should be moved left by an hour.  I just got sick of fighting Excel.
Rough indication is that SO users tend to ask questions in the morning and start answering them in the afternoon.  1 PM stands out, that's when Europe has answered what they could and, perhaps, starts switching to optional activities like editing.  I can't completely prove it of course, sounds right however.
Take it for what is worth, not much.  Notable too is that this was collected from SEDE data that covered the entire life of SO.  The numbers are much worse today, that graph is off the chart below 1.50 for 2013.  If SO had to pass the Area-51 beta test today then it would probably be closed down :)
Comment: What query did you use use for that? It would be interesting to point it at different sites with variations such as 'when are questions asked', 'when are answers given' and 'when are things closed'?
Comment: Intriguing, thank you for sharing @HansPassant, although i second the request of how you queried this info.  Do you have to be an employee to get that kind of logistics?  Or just a senior editor?
Answer: Mostly dealing with the C++ tag, I see a cyclic change in responsiveness on SO: During US office hours it seems more likely to get more and faster answers than outside of those. In fact, I sometimes did not bother to ask a question before it was afternoon here (Germany), because of this. I always considered this obviously related to the (assumed) fact that the majority of SO users are living in the US.
Around 1pm UTC is the morning on the US east coast. Likely that's when people arrive at the office and look at SO with the day's first coffee at hand, or when they sit down at home to look at a few questions/try to gain some rep before they go to work, or when they look at their tablet/phone while commuting.


Guitar making weird noise

Question: I have a normal acoustic Yamaha Guitar (starter version). It was working fine until now (5 months). All of a sudden the 2nd string is making weird noises when picked but only when the 6th string is pressed at the 12th fret or higher. I have no idea why it is happening. Any insights are welcome.
Comment: Can you please describe what "weird noise" it is making?
Comment: It is difficult to describe actually. It is producing the normal sound but beside that there is this irritating noise like bad electronic sound. It can only be heard only when i pick 2nd string and press 6ths string at 12 fret or higher. I can't see the connection. It is loud and clear that something is wrong but why at that particular fret and onwards is surprising.
Comment: Can you record the sound perhaps with a youtube video using a smart phone or other video/sound device? This could be  many things, it would save everyone a lot of time to get a more accurate 'picture' of the event. Endless possibilities: Strings (are these the original 5 month old strings?), Nut (hair caught in nut)? Bridge? Neck alignment? Finger nails too long causing a buzz? Body wrapped? Are the string ends on the tuning machines cut short, or hanging out? Are the strings at the bridge end secure? Loose fret ? etc?
Comment: Wow I didn't even know there could be so much problem. let me try to get the audio online. I'll add the link in that case. Thanks for your reply though.
Comment: @BraddSzonye "normal acoustic Yamaha Guitar"  I don't see any indication of pick up here.
Comment: @filzilla Oops, I saw the "noise like bad electronic sound" and thought he was playing an electric guitar.
Answer: This is almost certainly caused by a "cavity" on the silent part of the fingered e-string, resonating at a B frequency. Likely, it's the part between the nut and 7th fret (although the problem should already appear from 8th fret on then, not 12th). To test where exactly, finger one of the problematic notes and pluck the "wrong" part of the E-string at various lower frets. At some spots you'll likely hear that troublemaker sound, at B or perhaps F♯. Identify the outer boundaries of where this works; that is the part where you can directly tackle the problem. For instance, you can file down the upper delimiting fret (just ever so slightly); this will remove it as the undesired "bridge" it makes right now and, if not remove, then at least shift the resonance to a less problematic frequency.
The real problem might be that your neck is bent in such a way the frets are exposed in a problematic way. Consult an expert, maybe the neck can be adjusted to properly solve the problem rather than just removing the symptom.

Guitar making weird noise


what are the Cheap substitute of menthol that can be used in mint?

Question: i am preparing some candies and want to add some menthol for Cool effect in mouth but while searching on net i found that menthol is very costly so is there any cheap substitute of Menthol which can provide Cooling effect in mouth ?
Answer: There are absolutely no substitutes, neither cheap nor expensive.
First, the cooling effect is due to a very rare coincidence. It so happens that menthol is chemically capable of activating one of the temperature receptors in human skin (also present in the lining of the mouth). There are no other substances which do the same thing, at least not ones known in cooking (and if there happens to be some exotic option, it will certainly be more expensive to get hold of).
Also, even if you could mimic the cooling effect of menthol, you would never find a substitute which also smells of menthol, so people will readily notice the difference.
That being said, I am surprised that you find menthol very expensive. I found that I can get natural mint essential oil (which is about 50% menthol) for 8 Euros for a 40 ml bottle. This should be enough to aromatize about 400 kg of candy. And we are talking about expensive, naturally created stuff sold to hobbyists in a country with high standard of living. It could be possible to find synthetic menthol at cheaper rates somewhere, most likely at a pharmacy. Of course, it could turn out that there is no good supply where you live and the few people who sell it demand too much, but this would surprise me if it is a commonly used ingredient in your culinary tradition.
If you find that pure menthol is for some reason too expensive for your pocket, e.g. because the smallest batch you can buy is more than you will use up in a lifetime, you could just look at products meant for cooks which are basically diluted menthol. This includes mint extracts, mint syrups, mint essential oil, and a lot of other options, varying by region.
Comment: @Akhil Jain Why do you feel you need 100% menthol? Most candy is made with extracts. What is it about mint extract that you feel will not work?
Comment: Dosing it by the powder or crystal would be tricky unless you had a jewler's scale or an industrial operation. Buy a bottle of peppermint extract or something instead -- you'll only use a few drops for a reasonable sized batch of candy.
Comment: I don't know what you mean by "1 candies". I would say that you can use about 1 gram of menthol per 20 kg of sugar.
Comment: I would be surprised at menthol being costly, unless you live in a place with a very distorted market. From a simple search, here in Germany I can get pure menthol powder at 1.80 Euro for 10 grams, which is very cheap compared to other aromatics used in cooking. Now, you might live in a place where 1.80 Euro are a lot of money, but if this is the case, then any other food which is industrially produced and not locally grown will be also too expensive for you, so you are probably limited to minimally processed food anyway, and no concentrated aromas.
Comment: i am talking abt menthol powder and Crystal(100%menthol) which is costly.
Comment: how much menthol require for 1  candy ?
Answer: There is a known cooling perception effect from solid coconut fat melting, and such is used occassionally in commercial confectionery - but this is a different effect from menthol.


On bejeweled 3; diamond mine; how do you change from dollars to points?

Question: I was playing Bejeweled 3 (diamond mine) and the points went away and changed to dollars. how do you change it back?
Answer: I don't believe there is a setting that controls how your score is displayed in the Diamond Mine game in Bejeweled 3. I think that's just how they choose to show your score in the game (although in the Records section, scores are shown in points, and the Badges you earn are given for your score as points). The only options I see are global options for sound and video.


Solitaire rules for Catan Card Game?

Question: I want to play the Catan Card Game more often than I can find someone with the patience to play it with me. I know there are some good solitaire rules for Settlers of Catan, but are there any for the Catan Card Game?
Answer: It has been more than a year since I've asked this question. So, here are the rule modifications that I've play-tested. It seems to balance well, though I would like the game to go a little longer.
Objective: Get 12 victory points before 3 years are up.

Remove the following cards from play: "Conflict" event, Merchant, Herb Woman, and all Attack cards.
Shuffle Event cards without the "Year End" card. Pick 4 random cards from the shuffled event card deck and shuffle those 4 cards with the "Year End" card. Put this (5 card) stack on the bottom of the event card deck.
5 commerce points earns you the windmill token.
7 strength points earns you the knight token.
When a tournament is rolled on the event die, if your number of tournament points is greater than or equal to the number rolled on the resource die, you get one extra resource of your choice.

Feel free to critique.
Answer: Late reply is exceedingly late, but oh well. I tested these rules out and liked them; I also came up with some modifications I think add a little length and tension to the game.
Objective: Get 16 victory points before 4 years are up. (N.B. this is theoretically extensible for use with add-ons et cetera- the 4VP/1yr formula seems to balance decently.)
Additional stipulations:

Do not remove the "Conflict" event.
At the beginning of the game, roll the resource die 3 times, taking the top card of the appropriate development card pile each time (roll again on a 6). Place these 3 cards off to the side; they are the neutral player's hand, which can be affected by "Spy" cards or "Conflict" events (if you have earned the knight token).
If, at the end of your turn (after you have refilled your hand if applicable), the neutral hand has less than 3 cards: roll to refill the neutral hand to 3 cards in the same way as at the beginning of the game.
Every time the "Year End" card is drawn, repeat the process from the beginning of the game of shuffling 4 random cards along with it and placing them at the bottom of the pile. (N.B. this is also theoretically extensible in both directions- it excludes 0-X events from the current year, where X is the number shuffled along with the "Year End" card, so game length will tend to increase as X decreases, and vice versa. However, this also reduces or intensifies the impact of luck respectively- X=4 is a good balance of all factors.)
When playing development cards, you must respect type: red developments can be played only on the additional spaces provided by a city. These may be built before or after green developments, but a city may only have 0-2 green developments and 0-2 red developments.
A settlement (town or city) is considered "complete" when all of its development spaces are occupied (2 for a town, 4 for a city). Developments in a settlement confer their effects as normal (for example, knights contributing strength towards the knight token), but nothing in a settlement- including the settlement itself- is worth any VP until that settlement is complete. (This means a completed village is once again worth 0 VP upon upgrading to a city.)

Possibly intended by original author but not explicitly mentioned:

Rolling a windmill on the event die while in possession of the windmill token entitles you to a free resource, as though you "stole" it from the neutral player
The same goes for the "Merchant" cards, which essentially become free one-time 1:2 trades.

Again, feel free to critique.

Solitaire rules for Catan Card Game?


Can all domain users be logged into one local profile?

Question: I need to find a way to have all domain users log into a computer and all use the same local (could be temporary even) profile.  In the end, I only want one folder under USERS and I DO NOT want roaming profiles to be used.
Is this possible?
Answer: We need a bit more information to be able to fully answer your question, but here's a start:
Mandatory profiles force a given set of users to load a specific profile. When the user logs off, the profile is reset back to the mandatory profile saved. The standard process for assigning mandatory profiles does require that you store the profile on a server share and that you make some configuration changes to said domain users. This should work for you if you want this to apply to every machine the users log in to. If you only want it to apply when the users log in to a specific machine, edit your question to say so, and there are some other possible solutions.
As a side note, you may get better answers to this question on ServerFault, as this is more of an administration question.


Views contextual filter from custom taxonomy field

Question: I have added a custom field to taxonomy vocabulary. Now I need to use contextual filter from Views to display items that matches that custom field value in URL, e.g. /my_page/custom_field_value . Is it possible with Drupal 7 and Views 3.x ?
Answer: Yes!
If the view is a view of nodes you have to add the relation based on the term field, than you should have the contextual filter available.
Answer: Or you can use a term view with the custom field as the filter and create a relationship to content tagged with the taxonomy term.  That way you can modify the title of the view to match the term as well.


What is the Islamic ruling regarding a girl studying abroad?

Question: Does Islam permits a Muslim girl to go abroad/overseas and study in the absence of a maharem?
Answer: Certainly women/females are permitted to pursue their education and study. And this ruling is completely independent of gender and where you're going (Islamic or secular culture).
However this travel/stay should not come into conflict with other Islamic rules e.g. in case of married woman, traveling in spite of the husband asking not to or giving up on his Islamic rights (more or less like this).
There is another exception to this rule, which too is unisex, is that if one fears of being subject to at-ta'arrub ba'd al-hijra * then it's not permissible to go to such a place.
And the Prophet (saww) said to even travel to China (mostly meaning a distant place) if you have to seek education/knowledge. That saying is independent of gender.
*

Question: What is the meaning of at-ta'arrub ba'd al-hijra which is one of the major sins?
Answer: Some jurists have said that during our time, it applies to residing in countries that may cause the loss of faith. It means the migration of a person from a country -where it is possible for him to learn the obligatory religious teachings and laws, and where it is possible for him to fulfill his obligations and refrain from what is forbidden- to a country where this possibility does not exist fully or partially.
Source: A Code of Practice For Muslims in the West
Comment: Can you cite your sources?