What would be an appropriate way to introduce and discuss recent research in SQA?

Question: This is in response to https://sqa.stackexchange.com/questions/7759/sharing-relevant-research-with-the-sqa-community.  I don't know that posting a link to a paper in the question box and then discussing it in the answer boxes is what this Stackexchange site is about.  How do of other SE sites approach this?
Comment: What about posting specific questions about specific papers?
Answer: I think referring to recent research could make SQA more interesting and appealing to a wider audience, but we should to do so within Q&A framework.   There are plenty of discussion forums for SQA.  Our site is not one of them.
Here is an example of how you might refer to research in a question:

Here is a
  paper on AndroidRipper, a tool for automatically explores the app's
  GUI with the aim of exercising the application in a structured manner.
  Is there published evidence that AndroidRipper could shorten QA cycles
  relative to using other Android UI automation tools?

Note that the question asks for published evidence, not just speculation.  The question might also have asked for first hand experience with AndroidRipper, which would still be more valuable than speculation.  Concrete answers backed by evidence are always more valuable than speculation or opinion.
Here is an example of how not to refer to research in a question:

I read a
  paper on
  AndroidRipper last night.  It sounds cool; I can hardly wait to try
  it!  What do you think?

For that matter, this might be a valuable answer:

Yes, just last month, James Bach published a note in Software Quality
  Quarterly comparing the effectiveness of two test teams on very
  similar projects, one using TurboSelenium for Android.   and the other
  using AndroidRipper.  Although AndroidRipper had a steep learning
  curve, the AndroidRipper team produced twice as much code coverage as
  the other team in the same amount of time.  You can find a link to the
  paper here.

A less valuable answer would be:

No, I've never heard of it, but it sounds awesome.  Does anyone know
  how it compares to Quality Center?


What does THO, as in "USD THO", stand for in export statistics?

Question: I've noticed that some online sources use "USD THO" as a unit to express rates of transfer of value. Specifically, I saw it in measuring Chinese exports to Russia in this video at 21:20 https://www.youtube.com/watch?v=ce5TR-qWCk4&t=1280s and, when I tried to look it up to find out what it meant, I saw that it is used by tradingeconomics.com ( https://tradingeconomics.com/united-states/imports-of-consumption-of-carbon-steel-produc https://tradingeconomics.com/ecuador/changes-in-inventories ), iqstock.news ( https://www.iqstock.news/n/china-exports-crude-petroleum-3043534/ ), and a couple of South Asian economics papers ( http://doi.org/10.47205/plhr.2020(4-II)2.2 and https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3697430 (ISBN: 788 193 050774) ). Obviously, "USD" stands for "United States Dollar"; however, it is unusually difficult to find a meaning of "THO" which is obviously appropriate here. The best I've found are the "stock ticker" of Thor Industries at the New York Stock Exchange (NYSE: THO), Tahoe Resources inc. (which is invariably listed along with the words "Toronto Stock Exchange" when associated with "THO"), "Thai Offshore Baht" (Unless it's THai Offshore baht, don't ask me in what language that spells "THO", but apparently it does, as opposed to "THB" which is just Thai Baht. The currency apparently had very different "offshore" and "onshore" exchange rates from 2006 to 2008.), and some kind of cryptocurrency called "Thorus" (which has THO and sTHO tokens). None of these makes much sense to me. There's also something called a "Traditional Hand-Off", which is listed under "Technology, IT etc." by http://acronymsandslang.com/meaning-of/technology-IT/THO.html , though I can't figure out what it means, along with many other unpromising meanings I've found on that and similar sites.
Comment: Thousands seems likely
Comment: That's so obvious! I can't believe I didn't think of it.
There's probably an implied "per year" in at least some of those sources, too.
Answer: I had the same question. I found from another website that in Trading Economics parlance, this means thousands of US dollars (written as "USD THO").


How do I know when to replace my tires?

Question: The treads on my road bike's 28C tires are almost completely gone—they only persist along the shoulders of the tire.  Do the treads matter?  What is a good indicator of when the tire as a whole needs to be replaced?
Comment: See also: http://bicycles.stackexchange.com/questions/8740/how-often-should-i-change-road-bike-tyres
Answer: The tread on a road bike's tires is really quite unimportant and purely cosmetic.  Road bike tires have tread patterns because they sell better, not because they perform better.
Here's some questions to ask to decide about replacing a tire:

Can you see any of the fabric?
Are you getting flats more easily than you used to?
Is any part of the tire bulging out or lumpy?
Are there visible holes/gashes in the tire?
Does the wear indicator indicate you should replace?  (Some tires have dimples or grooves that are there to indicate when the tire should be replaced.  Some have an alternate color of rubber underneath, and when that shows through the tire should be replaced)

Smooth tread is actually ideal for road conditions, but not commonly found on tires.  If you're on hard surfaces such as pavement/asphalt, the tread doesn't help you and actually slightly reduces contact area and increases rolling resistance.  On most road tires the minimal tread pattern is just cosmetic to make their customers feel better (since a smooth tire looks slippery).
See also: Sheldon Brown's comments on tire replacement and tread patterns
If you plan to ride through mud, sand or other soft surfaces, you need tread.  So when you no longer have tread on your mountain bike or cyclocross bike's tires, it's time to replace them (unless you plan to only use them on the road).
Comment: I use Kojak smooth tires on my Bike Friday, and they're the best road tires I've ever had. (Although gravel *is* out of the question with smooth tires.) The thing is, there's a difference between smooth tires and bald tires: one is designed to be smooth, the other is not. I'd replace your tires, as per the conditions in freiheit's answer.
Comment: With regard to tread on road tyres Jan Heine has a decidedly different position: "There is another way to increase the interlocking between tire and road: provide edges on the tire that 'hook up' with the road surface irregularities." (Please note that he's with Compass, a tyre brand.)
https://janheine.wordpress.com/2018/02/22/myth-6-tread-patterns-dont-matter-on-the-road/
Answer: Many road tyres would have wear indicator. Usually that would be a small hollow on the tread. As long as it is visible the tyre is ok, once it is gone, the tyre should be replaced as that indicates that the main rubber layer is worn out, the grip is no longer that good and it may not be safe to ride.
Answer: For the last two worn-out road tires I replaced, I've noticed a pattern in wear that seems to be fairly consistent. This isn't a large sample size, but the tires were from different brands, and the wear seemed consistent with various comments I've seen from others. Based on your own tradeoff between cost- and safety-consciousness, you have to decide at which stage in the wear process you need to replace the tire.

First, the tread (if present) begins to wear. Not all road tires have tread, and in most cases it's purely cosmetic.
Then, the tire develops a flattened, almost squared-off shape instead of the round shape that a new tire has.
Next, the tire starts getting a lot of small cuts in a short period of time. This doesn't necessarily mean there are flats or that the cuts are deep. (After removing the tire, I could more easily see that the outermost layer of rubber was extremely thin and beginning to delaminate. This explains why I was seeing so many small cuts.)
Finally, the outermost layer of rubber wears through and threads begin to appear. By this point, the tire is definitely unsafe.

This process might not be exactly the same for all tire models, but I've noticed it in several of them. Of course, even a new tire should be replaced if it develops any signs of trauma as discussed in other answers (bulges, cracks, or gashes), or if the frequency of punctures increases.
Answer: I replace my tyres when i start to get a lot of punctures.
With new tyres, i rarely get punctures, despite what i see that i cycle over. after some time, and wear, i suddenly start getting a lot of punctures.
As a hypothetical that doesnt happen: If i dont get any punctures and i start to see the tyre fibers coming through, its definiely time to replace the tyre.
I know it meets no manufacturers or performance guidelines, but its a method that requires absolutely no monitoring and lets me get all the life i can out of the tyre.
Answer: Rubber degrades over time due to ultraviolet light damage and oxidation. Old tires where the rubber looks dried out with lots of cracking or rubber coming away from the fabric carcass should be replaced.

How do I know when to replace my tires?


Solat timetable

Question: I have a question regarding prayer timetable for muslims . Let say , the time for Asar is 4.30pm . Based on islamic-rules, Is it possible for we to take the prayer time to be anywhere between 4.25pm or 4.35pm ? Or one must take the 4.30pm strictly ? Please kindly answer my question . Thank you and that's all from me .
Comment: The title of your question is just too vague and broad. Please fix it.
Answer: It really depends on how the timetable was compiled.  Traditionally, prayer times were based on the position of the sun, not a particular time on a clock.  Prayer timetables, on the other hand, are often compiled for convenience rather than astronomical accuracy.
The start time for the asr prayer, for example, is based on the length of an object's shadow: The shadow must be equal to the length of the object (or twice the length of the object by some schools) plus the length of the mid-day shadow, and the asr prayer can be prayed any time from then until sunset.
So it's possible that your asr time would be, for example, 4:00pm until 6:00pm, and the timetable just sets 4:30pm because it's convenient (maybe that's when most of your community normally gets off work).  However, it could also be that your asr time is 4:30pm until 7:00pm, and the timetable is exactly on the nose; praying before the recorded time in that case would be ill-advised.
Giving a general rule in this case is impossible; you'd be better off asking at a local masjid where someone might actually know how the timetable was compiled, or checking the position of the sun manually.  However, the general rule of "When you hear the adhan, go to prayer" would still apply, whether it's called according to the printed timetable or not.
Answer: When we say that Asr prayer time is 4:30, that means that the prayer time starts at 4:30 and lasts until the start time of the following prayer , in our case Maghreb prayer.
Then you can not pray the Asr at 4:25, but you can pray it at 4:35
Comment: Welcome to [islam.se]. Please provide some reasoning to your answer. And go through [answer].

Solat timetable


Auto scaling Azure App Service by Queue Length

Question: Is there currently a way to autoscale an Azure App Service plan by a "v2" storage account message queue? When I attempt to set up autoscaling based on a message queue, it is only showing my "classic" storage accounts. I would prefer to not destroy and recreate the storage account as classic just because of this.
Answer: Currently that supports classic storage accounts only. I would suggest you to provide feedback here: https://feedback.azure.com/forums/169385-web-apps-formerly-websites


regression analysis

Question: "A model estimated with a large no. of observations may allow one to reject null hypothesis of zero coefficients for many explanatory variables.Thus we might choose to select  a somewhat lower significance to make rejection of a null hypothesis more difficult." Provide an intuitive explanation for the above statement.
Answer: This is called the "p-value problem in large samples" and s not limited to regression.  According to Cohen (1990): "a   fact   widely   understood among  statisticians:  The  null hypothesis,  taken  literally  (and  that's  the  only  way  you  can  take  it  in  formal  hypothesis  testing),  is  always  false  in  the  real world. If  it  is  false,  even  to  a  tiny  degree,  it  must be the case that a large enough sample will produce a significant result and lead to its rejection." This is a fundamental problem with p-values.
Another statistician Chatfield  (1995)  comments,  "The  question  is  not  whether  differences  are  'significant'  (they nearly always are in large samples), but whether they are  interesting.  Forget  statistical significance,  what  is the practical significance of the results?" The increased power  of  large  samples  means  that  researchers  can detect smaller, subtler, and more complex effects, but relying on p-values alone can lead to claims of support for hypotheses of little or no practical significance.
Looking at practical significance is a better solution than "select a somewhat lower significance to make rejection of a null hypothesis more difficult", although the effect is similar.
I found this article interesting : Mingfeng Lin et al.: "Too Big to Fail: Large Samples and the p-Value Problem".
An analogy might be the comparison of two coins (say 2 pennies): if you have an extremely sensitive balance, able to detect differences of a few atoms, you will find that any two coins you compare are always of different weight. A statistical estimator that uses a large sample is the equivalent of the very precise balance.

regression analysis


After Windows 10 Update, ICloud no longer installs. Hangs at removing backup files

Question: After Windows 10 Update, ICloud no longer installs. Hangs at removing backup files.  At this point, ICloud is installed and operating, but the windows installer hangs and requires a reboot if any install or uninstall is needed.  After a reboot, ICloud is automatically uninstalled.  I have tried all fixes recommended on the web, but nothing works.
Answer: I was told by a Microsoft technician that if your computer had Windows 10 installed as a virtual copy to your computer as opposed to having the physical install disc and installing from disc then the iCloud installation cannot remove the the backup files as they don't exist in reality, they only exist in the virtual copy of the program.  I may not be explaining this completely accurately but the jist is that if your original set up was from the factory where they used a "photo" copy of the program data to your hard disc in lieu of doing an actual install, then iCloud will always have problems.
Comment: Although a Microsoft technician gave you that explanation, it seems unlikely that his explanation is the correct answer.  Why would ICloud need to remove Windows 10 installation backup files?  I spoke at length with Microsoft and did not get that kind of answer..


Who wrote the "Linux kernel" (Linus Torvalds and his team)?

Question: Who are the authors of the pure Linux kernel from scratch, which was integrated with GNU tools and formed the full GNU/Linux Operating system in the 1990s? I have read some wiki articles but I haven't got any clear cut idea on the history.
Comment: There is a [good documentary on Youtube](https://www.youtube.com/watch?v=XMm0HsmOTFI) about the subject. The narrator's English is a bit annoying and you'll need to turn on the captions (some bits are in Finnish) but I found it very useful.
Comment: Did you try: http://simple.wikipedia.org/wiki/Linux ?
Answer: The wikipedia page has a fairly clear history. Linus Torvalds, then a student, wrote his own kernel in the summer of 1991 because he was unhappy with the available Unix kernels: Unix itself (with the Bell Labs code) was extremely expensive (even PC unices such as Xenix), there was Andrew Tanenbaum's MINIX but it was only available to purchasers of Tanenbaum's book, and Torvalds was unaware of the effort led by Berkeley University to produce a free Unix (BSD), and BSD didn't run on PCs yet at the time.
Since then, thousands of people have contributed to the kernel, most of them in the form of drivers.
Answer: Richard Stallman, father of the GNU Project
Linus Benedict Torvalds, the author of Linux OS(Linux version 0.01 was released by mid September 1991).
The real story is :
Year 1991 :
DOS brought by Bill Gates was reigning the world of personal computers. The other player in the personal computer world was UNIX by Bell Labs, but it was extremely expensive and the source was not publicly available.
Then there was the MINIX by Andrew Tanenbaum, which was not a superb OS but made the source code was publicly available. Tanenbaum captured the souls of computer science with the elaborate and lively discussion of the art of creating a working OS. Students of Computer Science all over the world went through the book, reading through the codes to understand the very system that runs their computer, and one of them was Linus Torvalds.
The GNU project created a lot of the tools line GCC, etc. but still there was no OS.
For rest of the story and how Linux was written please read through the following link.
Linux History Time line :
Comment: The kernel itself doesn't derive from the GNU project, but the GNU project is relevant because it made gcc, which as far as I know Linux used from the start. The MINIX source code was then not open source, you had to have purchased Tanenbaum's book.
Comment: @Gilles: You are right..
Comment: @Renjith: When you down vote an answer could you please put the reason also, so that i can improve my future answers on the forum.
Comment: Thank you very much for your answer , It is nothing like that as per your words.
Answer: I have had the privilege to hear RMS (Richard M. Stallman) and Linus Torvalds. In RMS's own words, Linus made the kernel and from the e-mail that is now well-known on the comp.unix.os newsgroup http://www.linux.com/news/software/linux-kernel/734956-linuss-famous-email was to make it a toy project. The similarities between the kernel project and the GNU utilities project is that both use a derivative of the GPL license, the monolithic kernel being mostly a GPL2 with some parts in GPLv3 while most GNU projects are strictly GPL2.
Off-topic to the question but still relevant - the GNU project has its own 'Hurd' kernel project where the user is never supposed to touch the core kernel and would just be touching the various sub-systems to do whatever he/she desires.This is supposed to increase security and is bit more modular and can be experienced nowadays via a VM. Once we see it in actual devices (maybe forever) we will really know what the real-world performance is like.
I am also not sure what Linus made (kernel 0.1) should be termed as an OS. Typically an OS would having a kernel, having one or more compilers, bunch of utilities and a user-facing interface which essentially is what a GNU/Linux distribution is.
Just my 2 paise.
Comment: "Typically an OS would having a kernel, having one or more compilers…" nope. The OS is the kernel and nothing more.
Comment: @msw You shouldn't confuse OS and kernel, especially when talking about Unix and Linux OSes. An OS is something able to boot, run processes, applications, services which a kernel alone can't. As far as Unix is concerned, an OS is at least a kernel, a standard C library and standard CLI utilities (`sh`, `ls`, `cat` and the likes), the basic libraries and utilities are usually provided by GNU on Linux. You are however correct saying a compiler is not a mandatory component of a Unix (like) OS.
Comment: @jlliagre [Nope](https://en.wikipedia.org/wiki/Operating_system): "An operating system (OS) is software that manages computer hardware and software resources and provides common services for computer programs. The operating system is an essential component of the system software in a computer system. Application programs usually require an operating system to function."
Comment: @msw Nothing in your excerpt or the wikipedia article contradict the well known fact the kernel is just one of the components, even the most critical one, of an Operating System. Other components include a boot loader, a standard library to interface the kernel and the userland, some kind of init daemon to launch initial programs and reach some expected state, and basic utilities to allow scripts and CLI to work.


NFC library for M24SR64

Question: Im currently working on a project where i build an NFC device and needed some guidance in regards to the library needed for the NFC chip to work on the Arduino IDE. The chip is an M24SR64 chip and i've looked online for the library related to the chip but i couldn't find it. Although i did found a library for the M24SR64-y chip, though i'm not sure if its possible to use it, or whether it will work. If anyone has an idea or any help it would be much appreciated
Answer: Here you will find a lib for all M24SR NFC tags
In this test sketch you find details how to connect and test the tag with Arduino. If it helps mark as accepted to help others.

NFC library for M24SR64


Will the magnetic field still remain if there is no current in the electromagnet? Why

Question: Will the magnetic field still remain if there is no current in the electromagnet
Answer: There are two ways of having electromagnets, as seen in the introduction here.
a)

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole, denoting the center of the coil. The magnetic field disappears when the current is turned off.

That is one kind of electromagnet. Or:
b)

The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.

Ferromagnetic materials retain an imposed magnetic field, so for these electromagnets there will be a remainder field even if the power is turned off.
Answer: Faraday's laws of induction states that for a change in current in one conductor there is a proportional change in magnetic flux induced by it.
In your case as the conductor has no current for long time hence leading to inference that change in current is zero so there will be no induced magnetic field.
Hence the electromagnetic loses it's magnetic strength.

But coming to a realistic world does it always happen?
No
Your magnetic flux carrier material is made of ferrous materials hence it has prominent dipoles. In case the carrier has the magnetic field for a long time the dipoles will align and hence give the material a permanent/temporary magnetic characteristic, making it essentially a powerful magnet.
And this is also a major reason why choice of material is necessary while building electromagnets.
Higher retentivity leads to higher residual magnetic character in the material even after the current is cut off.
Answer: No, I mean it will remain still at zero, but that's not what you're asking I guess.
For a material to maintain magnetic moment, which is the only possible way you can generate static magnetic fields, it needs to be properly magnetized. There are only certain materials that can be made into magnets (see here), and the conditions for which they will become permanent magnets probably will not occur in a electromagnet.
So, no, the magnetic field does not remain in the electromagnet after the current is cut, because there is nothing that will continue to provide magnetic field.


I need to know how to get my wireless to work

Question: I have a Acer Aspire 1800 series. Switched from Windows 7 to Ubuntu 12.04.New to Linux; need help, please.
Comment: Did ubuntu automatically find the drivers?  what is the output of `iwconfig`? if it shows wlan0 or something like that then you just need to use NetworkManager to set it up.
Comment: Welcome to Ask Ubuntu! We need more hardware information to help you, can you look at [this question](http://askubuntu.com/questions/14008/i-have-a-hardware-detection-problem-what-logs-do-i-need-to-look-into) and then edit your question adding the information?
Answer: Are you saying that you do have a wireless router working, and you intend to connect to the wireless network in Ubuntu 12.04? In this case you might want to check out the bar at the top of the screen; there is an icon, by clicking which you can see something like
Enable Wireless Network. Make sure it's ticked and you should be able to find your network in that popup menu. Click on the network and follow the instructions!
Comment: my system came with 802.11 b/g wireless LAN. With Ubuntu 12.04 it does not work. I have a 1800 Series Acer that came with Windows XP
Answer: Hit CTRL+ALT+t, then type this in:
<code>lspci | grep -i network
</code>
Then highlight the resulting text, right-click, select copy, then paste it as a response here. This will show what type of wireless you have, and we can help getting it working from there.
Other things to check: 1.) Ensure your physical wireless switch is left in the on position when you start up. 2.) Plug in the Ethernet cable and try running the updates from the "Updates Available" menu item (4th down) on the on-screen power button in the upper r/h corner of the Ubuntu interface.
Comment: Shannon just call me and we can get it cause I'm no good at linux. 5174029418


Why are all answers on certain questions community wikis?

Question: Why is every answer on this question (as well as the question itself) a community wiki?
Comment: See [How does a post become a Community Wiki post?](http://meta.stackexchange.com/questions/11740/what-are-community-wiki-posts)
Comment: @approxiblue that details the behaviour now not then.
Comment: @MartinSmith It details both. "In the past, questions could be made community wiki by their authors or by certain automatic triggers..."
Comment: @approxiblue - It doesn't give any details on the automatic triggers.
Answer: In the olden days a question (and all answers) got converted to CW if the question reached  30 (undeleted) answers.
I imagine that's what happened here.
All of the answers' edit histories, and that of the question, contain

Post Made Community Wiki by neuhaus    occurred Jul 29 '13 at 14:07

And that user posted their answer at that time.
Comment: And this no longer happens?
Comment: @Aequitas no. The automatic community wikification was abandoned.
Answer: Quoting the MSO answer for "What are "Community Wiki" posts?",
TL;DR,

An answer posted to a community wiki question will also be community wiki.

In this case, the question itself if CW, so are the answers.


How much is idiom "chew the fat" acceptable and neutral?

Question: Does the idiom have strictly negative meaning or is it neutral? Can it be used to talk not only about close people so that not to insult anybody?
Comment: I'd say it's not pejorative at all. But as to register, you chew the fat with your mates, not your colleagues (unless it's a works do).
Comment: I agree with @EdwinAshworth that it's not negative, and go a step further to suggest that it is in fact positive. But it is a colloquial expression with a notable "ick" factor and should be used with discretion. The President would probably not use it in a State of the Union Address, for example—yet he *might*.
Comment: It doesn't have a negative meaning on its own. However, since the idiom refers to informal, idle small talk, people may take offense if you describe talking about a serious matter as "chewing the fat" because they might think you're trivializing the subject matter.
Answer: According to J.E. Lighter, The Random House Dictionary of American Slang (1994), the word originally (in British usage prior to 1885) meant "to grumble" although it seems to have lost that sense long ago:

chew the fat to converse, gossip, or chat. {In British use before 1885, as "to grumble" (OEDS).}

(Lighter finds examples of U.S. usage of the term going back to 1907.)
So whether "chew the fat" carries a pejorative edge in a particular instance  depends on whether you interpret it in that case as implying "to converse" (not at all negative) or "to gossip" (often mildly negative or disapproving). Either way, as both Edwin Ashworth and Robusto observe in comments above, it's a very informal expression.


How to display cross symbol as superscript with unicode?

Question: I want to display a cross in the place of superscript, I know the unicode character of the cross (\u2020).
Answer: Unicode encodes plain text. Superscripting isn't plain text, so you need something external to, or "on top of" plain text. For example, on a web page, you could use the CSS to position character above the baseline (and reduce font size). In a word processor, you would use superscripting command or style.
In Unicode, there is a limited number of superscript characters, i.e. variants of characters in superscript style encoded as separate characters, such as superscript two "²". But Unicode has no mechanism for superscripts in general.


How can I make auto-hide/show feature for the dock activate a few millimeters above the bottom?

Question: I like the auto-hide/show feature for the dock but I don't like how I have to go all the way to the bottom of my screen in order for the auto-show to activate.  Is there a way I can get it to auto-show a few millimeters above the bottom of the bottom?
Answer: What you see is what you get, unfortunately. I think it is baked into the UI and is not user modifiable.


Creating polygon using coordinates

Question: I am using QGIS 3.2 and I need to create an area to form a polygon shapefile using latitude and longitude, not using Python as I am just a beginner. How to do this?
Comment: Some of the CAD drawing tools should be what you're after: https://gis.stackexchange.com/questions/34204/creating-point-features-with-exact-coordinates-in-qgis
Comment: There are various text file formats, that can be imported into QGis. Is importing a text file an option?
Comment: If You have Your latitude and longitude and perhaps other data in a table, you could use a plain .csv file and load it as text-layer: https://docs.qgis.org/2.18/en/docs/user_manual/managing_data_source/opening_data.html#importing-a-delimited-text-file
Answer: To give an example according to @geom recommendation. You must use the syntax to define polygons in WKT format,  here an example in CSV:

Finally use add delimited text data source:

With the following result:

To edit the question to provide an example of where I need to create a polygon via distances.
I need to create a polygon to represent a survey area. The survey area required is 3.58km x 3.0km. I have used the v.buffer GRASS tool and the Buffer tool. Which I select a certain point to buffer Around to create the survey area. However I cant find any input within these tools where I can enter such distances. Do you know how to fix this?
Comment: perfect, thank you for providing an example. Would I follow the same formula if I wanted a polygon with specific dimensions rather than coordinates. e.g length in km.
Comment: Could @Bodhi provide some example, some data to provide what you require? I think it's best to do the coordinate calculations from the dimensions in the spreadsheet and then perform their representation in QGIS.
Comment: sure, Provided an example in the problem
Answer: Use geojson. Just create a valid .geojson file with contents such as:
{"coordinates": [[[31, -5],
                  [32, -5],
                  [32, -4],
                  [31, -4],
                  [31, -5]]],
 "type": "Polygon"}

You can use a tool like geojsonlint to make sure the syntax is correct. Once you have a valid geojson, save it to a file, e.g my_polygon.geojson. Then, just drag and drop it to your "Layers" in QGIS. That's it.

In my opinion, this is much easier than the methods mentioned in other answers.
Comment: Note that geojson must follow the right-hand rule: https://mapster.me/right-hand-rule-geojson-fixer/
Comment: yes true. geojsonlint that I suggested checks that
Answer: An addition to the answer above: I found it pretty complicated to write the WKT using the  boundary coordinates myself. If you have Postgres with Postgis extension (and possibly pgadmin) available (use the Docker version!), just execute the following:
SELECT ST_AsEWKT(ST_MakeEnvelope (
    12.147653576, 50.978794549, --lng-lat bounding
    13.216635542, 51.684973715, --lng-lat box limits (Example)
    4326))

You will get back the eWKT formatted string:
SRID=4326;POLYGON((12.147653576 50.978794549,12.147653576 51.684973715,13.216635542 51.684973715,13.216635542 50.978794549,12.147653576 50.978794549))

This can be loaded using the answer above in QGIS with import CSV or using the "QuickWKT" plugin
For anyone who still wants to do this manually, here's the format for 2-coordinate bbox-polygon:
POLYGON((
left-lng bottom-lat,
left-lng top-lat,
right-lng top-lat,
right-lng bottom-lat,
left-lng bottom-lat))

Creating polygon using coordinates


Default dialer issue

Question: I am using samsung S3 and installed Truecaller on this, now when i make a call from truecaller, the options shown in the popup are only the default dialer and Skype, not truecaller. I have cleared all defaults and tried it with multiple dialer apps, but everytime I see only these two options for dialing out. Any idea on how i can use truecaller for dialing out?
Thanks
Mayank
Answer: That's the way it should work. Truecaller just provides a dailer. It is not a call handling application. The main motto of the Truecaller dailer is to show info of the number before a call is placed.
Comment: Thanks Mani. I installed exdialer and the result is same. I restored default factory settings on my phone 1 month back, prior to that this was working fine with me getting exdialer as option.

Default dialer issue


Is this a termite wing or flying ant wing

Question: I saw this on the bottom corner of my pantry in the Washington DC area. I can't tell whether is termite wing or something else. The wing is 3/4" long.
Comment: I agree it is a great photo but as a person who has had both problems, can you give more details, inside outside any debris ? And where in the world are you! In the Pacific Northwest I can say yes it is!!! Oops not much info so my answer oops comment could be?
Comment: If you don't find an answere here find an entomology forum or "what's this bug" because the ID is very specialized entomology.
Comment: FYI the [Comstock-Needham system](https://en.wikipedia.org/wiki/Comstock%E2%80%93Needham_system) might be useful here.
Answer: This appears to be the wing of a crane fly (Tipulidae).  Using this figure you can begin narrowing down the possibilities for wing venation. Searching diptera wing venation, I think, brings up this excellent diagram (see bottom left for Tipulidae) which quite closely matches your photo if rotated in a graphics program (GIMP):

 Wing photo from OP paired with wing outline image copied and rotated from Batsdiet.com
You could likely drill this down further by searching Tipulidae venation or the like on Google Scholar, which pulls up many papers with detailed information on various regions and taxa of crane flies.
Comment: You might further cite evidence that crane flies have wings this size. For example, quickly [Wikipedia](https://en.wikipedia.org/wiki/Crane_fly) suggests they can range from 1-6.5(11) cm, which safely includes the size of the OP's specimen. You might also note that crane flies *are* present in DC.


android image processing tutorial?

Question: Does anyone know of any good image processing tutorials for android? I'm new to android, and I'm coding an app that places an effect on a bitmap. I can find plenty of tutorials in java, but android does not support awt. I'd like to manipulate the pixels in the bitmap just using the android sdk, e.g. warping, fisheye etc. I can access the pixels and change their colour but I'm not too good with transformations, and not sure where to start.
Comment: Any chance of charing the code with the rest of the world?
Comment: @netlander of course there is sir. I've got the app effect working now and did so in Android alone. i re-coded a filters class to use bitmap instead of buffered image. http://stackoverflow.com/questions/1927145/how-to-simulate-fisheye-lens-effect-by-opencv
Answer: Check this out (scroll down after [The Basics] 29):
http://xjaphx.wordpress.com/learning/tutorials/
Has some great tutorials like:

Mean Removal effect
Smooth effect
Emboss effect
Engraving effect
Boost up color intensity
Rounded Corner Image
Watermarking on the fly
Image Flipping / Mirroring
Pixel Color Replacement
Tint Color
Flea / Noise Effect
Black Filter (Increasing the Darkness)
Snow Effect
Shading Filter
Saturation Filter
Hue Filter
Image Reflection Effect
Draw Text on a Curve
Comment: Is there anything for image tagging?
Comment: @Sauron : you can try this: http://www.alchemyapi.com/products/alchemyvision/image-tagging
Answer: You can also checkout JavaCV that give you Java Objects with bindings to opencv lib.
This way you wouldn't need to do any c/c++ coding, you can do all directly in Java and access functions from opencv.
Google code Project
Answer to your followup question:
For example, take a cylindrical projection: Take a look at the image -

(sorry I'm not allowed to post pictures)
 this is taken from Szeliskis book (http://szeliski.org/Book/).
The relation you have here in the end is
x'=s*tan⁻¹(x/f)

and
y'=s*(y/sqrt(x²+f²))

where f is the focal lenght of a camera and s the radius of the cylinder, you can use f=s.
Now to get this into loops, here is some pseudocode:
%% xMitte , yMitte are the coordinates for the point in the middle
for yNeu =1: height
   for xNeu =1: width
      dx = xNeu - xMitte ; %% X relativ to origin
      dy = yNeu - yMitte ; %% Y relativ to origin
      theta = atan(dx / f);
      h = dy / sqrt(dx ^2+f^2);
      x = (f * theta) + xMitte ;
      y = (f * h) + yMitte ;
      BildNeu (xNeu ,yNeu) = BildAlt (x, y);
   end
end

BildNeu is the new picture, this array has the same size as BildAlt (the original picture).
The Line with BildNeu and BildAlt at the end of the inner loop could be like:
/** returns the color value of that pixel **/
CvScalar pixel = cvGet2D(originalImage, i, j);
/** writes the new color value of that pixel **/
cvSet2D(destinationImage, y, x, pixel);

Comment: ok thanks, is it easy to do radial transforms using javacv?
Comment: I have to say that I never worked with javacv... only directly with opencv (android branch => http://opencv.willowgarage.com/wiki/AndroidTrunk). You can do transformations if you know the transformation matrix very easily, else if you just know the formula for the projection you want you can write loops and transform every pixel to the new coordinate by your own.
Comment: hi thanks for getting back. i found a post where somebody had transcribe a fisheye distortion from C++ into java. It used awt's bufferedImage so i just matched up the setARGB methods in that class to the corresponding setPixel methods in the bitmap class and it works:). i would be interested in what you mentioned above with the loops. how would you do that if you only know the formular for the projection? how would i transform each pixel to it's new coordinate? do i just have a src array and a dst array and apply the formular?
Comment: @turtleboy I added an example in my answer (as formatting in the code is not possible that it looks nice. And sorry for not translating variable names but I just copy pasted from my diploma thesis (on German) as I've explained in there the projection I used in my code
Comment: Thanks alot for the example and taking time to share it. Maths is not my strong point but i'll have a look. i've found some code that works that somebody transcribed from c++ into java. i then refactored that code to work with a bitmap instead of bufferedImage. But i need to delve deeper into graphics for my own benefit. thanks again. matt
Answer: OpenCV Android is preferred due to the ease of use on an Android platform, although there maybe limitations. Here are some references that might help:
1.The best way to learn Image Processing on an Android platform is via implementation. Try running and understanding the existing OpenCV4Android Samples on Android Studio/Eclipse. They are available on https://github.com/joaopedronardari/OpenCV-AndroidSamples .
The description of each sample is available on the OpenCVAndroid Samples page. Mixed Processing, Camera Control, Image Manipulations and color-blob-detection deal with pre-processing and image manipulations. They comprise:
RGBA and GRAY preview
Canny (Edge Detection)
Finding Features
Colour Effects
Histograms
Sepia
Sobel Filter
Zoom
Pixelize
Posterize
Watershed transformation
Markers (blob detection)

Since you will be working on a Java platform ,the OpenCV Java tutorials will be of use.
http://web.stanford.edu/class/ee368/Android/ has sample projects.

4.Check out The Android Arsenal, for Image Processing libraries.
Note:A Mat object has to be converted to a Bitmap object, in order to display it on the device screen (ImageView).
Comment: This is the world's most difficult and complicated library to import
Answer: Perhaps you will have some success with the OpenCV java bindings. Other than that there is not really anything that I know of that will help.

android image processing tutorial?


Three-Dimensional Gravity

Question: Does anyone have any references that discuss gravity in three-dimensions? I'm trying to make my way through some papers by Witten relating $SL(2,\mathbb{C})$ Chern-Simons theory and gravity in three spacetime dimensions and would like some explanation about the latter of the two topics.
Comment: Please tell us which papers you have in mind precisely so that we don't give you references you already have. There's e.g. this http://arxiv.org/abs/0706.3359 and this http://adsabs.harvard.edu/abs/1988NuPhB.311...46W
Comment: Yes, those are precisely the two papers I'm starting with. I'm wondering if there are any papers/books which lay out GR in 3 spacetime dimensions. I am only familiar with Carroll's book, Wald, and MTW. I have seen Carlip's book, but still waiting for it to be returned to the library.
Answer: The t'Hooft references started the modern field, and they are in my opinion the best for first learning the subject, because they are self-contained and they allow a full simulation of the classical dynamics. These are taken from t'Hooft's web page:

Causality in (2+1)-dimensional gravity. Class. Quantum Grav. 9 (1992) 1335-1348
Classical N-particle cosmology in 2+1 dimensions. Class. Quantum Grav. 10 (1993) S79-S91
The evolution of gravitating point particles in 2+1 dimensions. Class. Quantum Grav. 10 (1993) 1023-1038. http://www.staff.science.uu.nl/~hooft101/gthpub/evolution_2plus1_dim.pdf

The last paper is available online, and gives a complete numerical implementation and numerical results.
Answer: Steve Carlip wrote a book, quantum gravity in 2+1 dimension. He also has a review article on Living Review.
Answer: It is unclear to me whether you're asking for a resource on three-dimensional gravity(and general Chern-Simons) or refined resources on three-dimensional gravity and SL(2,C) Chern-Simons. An excellent survey connecting three dimensional gravity to (general) Chern-Simons, via the usual methods -- vector bundle parallel transport, Wess-Zumino-Witten action, etc. -- is "3D Gravity, Chern-Simons and Higher Spins: A Miniature Introduction" [Kiran, KS. 14].
If you are unfamiliar w/ how 2+1 gravity is related to general gauge theories -- w/ (first-order) einstein-hilbert action in (2+1)dim proportional to chern simons three-form, etc, -- this text is an excellent introductory read.
For a more specific read on SL(2,C) Chern-Simons and (2+1)dim gravity, I suggest "Three-Dimensional Quantum Gravity, Chern-SImons Theory, and the A-Polynomial" [Gukov, S. 03]. The text focuses especially on hyperbolic three-manifolds and (Alexander / Jones) knot invariants, most of which likely unrelated to the topic of interest [Witten, E. 07], but the result regarding SL(2,C) Chern-Simons partition function and coloured jones is quite exceptional and may be of some use in your readings.
note: for introductory readings on (2+1)dim gravity itself, there is an excellent survey on "exactly solvable" models in "2+1 Dimensional Gravity as an Exactly Solvable System" [Witten, E. 98]. Not to mention, "Developments in Topological Gravity" [Dijkgraaf, R., et all. 18] surveys the topic, where Topological Gravity is elegantly related to matrix models of (2+1)dim gravity via "Weil Peterson Volumes and Intersection Theory on the Moduli Space of Curves" [Mirzakhani, M. 07], etc.

Lastly, as someone quite familiar w/ the text "Three-Dimensional Gravity Revisited" [Witten, E. 07] I recall the topics of extremal holomorphic CFTs (and dual pure AdS3) where of particular importance, specifically where AdS3 has maximally negative Cosmological Constant and the CFT has central charge c=24.
The paper is particularly interested in the following case due to the CFT partition function being proportional to the graded character of the moonshine module. Similar work regarding the monster CFT was completed by "Vertex Operator Algebras and the Monster" [Frenkel, IB., et all. 88] in the so called "Frenkel-Lepowsky-Meurman conjecture" relating the moonshine to vertex operator algebras of central charge c=24 and j-744 graded dimension -- used to study monster CFT via pure AdS3 gravity w/ maximally negative Cosmological Constant.
The difficulty had in this paper, an papers related to it, i.e. "Chiral Gravity in Three Dimensions" [Strominger, A. 08] (refined arguments on the stability of consistent AdS3 w/ suitable partition function via chiral monster CFT), etc., is the language of monstrous moonshine, monster group, and general moonshine -- especially in the case of newer work; i.e. "Notes on the K3 Surface and the Mathieu Group M24" [Eguchi, T., et all. 10], etc. I recommend "Monstrous Moonshine" [Conway, J., et all. 79] and "Vertex Operator Algebras and the Monster" [Frenkel, IB., et all. 88] as general introductions to the topic, from the point of view of a mathematician and physicist respectively.
I hope any of that was of any help!

Three-Dimensional Gravity


Output either 0 or 1 for every 24 frames using animation nodes

Question: I want an output of 0 for the first 24 frames, 1 for the next 24 frames, 0 again for the next 24 frames and so on.
That is, at frame one the output text is 0 and after 24 frames the output changes to 1 and after the next 24 frames the output changes to 0 again.
How do I do this using animation nodes?
Answer: Here is an example,
1) Repeat node is giving values from 0 to 47 i.e 48 when the rate is 48.
2) Because repeat node also count 0, so I have substracted 1 from frame.
3) Then using compare boolean and switch nodes we can choose 0 for 0-23 frames (24) and for next 24-47 (24) frames, 1.
4) Last I use float text node to convert float to text and text object output to text-object.
Answer: Okay, so after some thinking I found the right nodes and it wasn't as complicated as I thought it to be. I've attached a picture of the node tree.


Xbox 360 Forza Horizon disc scratched. Is progress and data lost?

Question: My son scratched his Forza Horizon disc and now it keeps freezing on him. If we buy another disc, will all his data and progress be lost?
Comment: Note that many game stores offer disc resurfacing - often a much cheaper option.  Even if their resurfacer is not professional-grade, it could restore the disk enough that you can install the game to the hard drive of the Xbox and not need to buy a new anything.  Most stores like GameStop charge in the $5 to $10 range to resurface a scratched disc.
Comment: Consider switching to digital purchases in the future − no need to deal with a fragile optical disc with those.
Answer: No. Save data is stored on either the internal memory of the console, or on external memory devices. It is never stored on the disc. A new disc should be able to read the previously saved data just fine.
Answer: All optical discs for consoles of the 6th, 7th (includes Xbox 360) and 8th generation are read only media as far as I know. Nothing can be stored on these discs after they have been created in the factory. The stock optical drives in these consoles are also missing the capability to record or "burn" on such media even if you use writeable discs.
So a "savegame" that stores the progress has to be stored somewhere else. Earlier generations used special memory cards for this purpose. The first Xbox introduced a hard drive in the default configuration, with the 360 memory cards (earlier models) and hard drives were optionally available (to reduce the price at that time). On later models of the 360 a portion of internal flash memory was available for additional game content and savegames. USB drives have almost replaced memory cards and Xbox Live Gold offers to save progress to online storage, which is the default on Xbox One.
Apart from different locations where progress can be stored on current consoles you should make sure that the replacement disc is compatible and not a different edition of the game or specific to another region. This is a rather rare case, but for example I have DOA5 and DOA5U which are detected as two completely different games where achievements are exactly the same but both games have separate entries. The newer edition knows about the older and can import progress, but this functionality is completely up to the game manufacturer to implement. (To add to the confusion DOA5U was patched to DOA5LR. :D) More related to Forza, Forza Horizon 2 is available on Xbox 360 and Xbox One, but both are completely different games and even though you can save your progress online in both games, they're not compatible.
I don't see any issues with Forza Horizon in your case, but as suggested, trying to resurface the disc is the first option I would try.


How to Auto-deploy with Jboss

Question: How to automatically deploy a project with jboss as 7. Is there a way to automatically deploy a Project using the Jboss-cli.sh in Jboss as 7?
Answer: I was searching the Internet for this answer and could not find it. I recently figured it out and thought I would share. I wrote a linux shell script that works perfectly. Taking the time to deploy while developing from 2-3 minutes to 10 seconds which makes programming so much faster.
Here is my script:
 #!/bin/bash

cd /home/samo/EAP*/bin
./jboss-cli.sh --connect <<EOF
undeploy FlcErp.ear
deploy /home/samo/NetBeansProjects/FlcErp/FlcErp/dist/FlcErp.ear
EOF

first line of the script navigates to the location of your server bin.
the second line opens jboss-cli.sh and connects to the instance.
everything after <<EOF and before EOF are commands you can send to the jboss-cli.sh program. In this case I undeploy my current instance which is FlcErp.ear then I deploy the full location of my project.
You then save this file the file with your desired name "Deploy" change the permission with chmod 755 Deploy
Then add this file to your path with: export $PATH = $PATH:/home/samo/bin
to execute file just type filename into terminal

How to Auto-deploy with Jboss


Rewrite to remove url - kohana 3.2 and .htacess

Question: My installation of Kohana 3.2 works well. The site is navigable and also the CRUD functions works. He is in the example address: www.site.com.br/folder/.
At .Htacess I have

     # Turn on URL rewriting
     RewriteEngine On

     # Installation directory ()
     RewriteBase /folder/

     # Protect hidden files from being viewed
    Files .*>
    Order Deny,Allow
    Deny From All
    /Files>

     # Protect application and system files from being viewed
     RewriteRule ^(?:application|modules|system)\b.* index.php/$0 [L]

     # Allow any files or directories that exist to be displayed directly
     RewriteCond %{REQUEST_FILENAME} !-f
     RewriteCond %{REQUEST_FILENAME} !-d

     # Rewrite all other URLs to index.php/URL
     RewriteRule .* index.php/$0 [PT]

When I write the complete url www.site.com.br/folder/ url it work.
But now the server is pointing to the root and I need to be like www.site.com.br, in other works, remove the folder/.
I tried some options but the Kohana stop working:
RewriteRule .* folder/index.php/$0 [PT] or
RewriteRule ^folder/(.*).* index.php/$0 [PT]
Answer: You only need to remove the RewriteBase from the HyperText Access script. Then, the URI's will be parsed correctly within Kohana.


Is this a good design to use Unit Tests Framework for E2E testing?

Question: Is this a really good idea to use Unit Test Framework for End-To-End testing ?
I'm thinking about method annotations to trigger test execution.
Since we don't have a lot of control about the execution order and concurrence...
Is this a common way to execute E2E tests ?
Answer: A little more detail would be helpful. What do you mean by end to end tests? Front end tests with Selenium maybe? Or API testing flows touching multiple endpoints and maybe a DB? What programming language are you using?
The short answer is YES, you can and should use a unit testing framework for end2end testing. I'm not sure how you could do it without one, as all IDEs I've worked with use some sort of unit test adapter to discover tests.
Answer:
Is this a really good idea to use Unit Test Framework for End-To-End testing?

This question can be interpreted in multiple ways.
First, if you are asking "can we use the same tools for e2e testing as unit testing?" then yes you can.
For example, if you are using JavaScript, you can use Mocha/Chia, Jasmine, or Jest for both unit tests and e2e tests. While they are made initially for unit tests, they have been adopted for many testing use cases, including e2e tests. These tools allow you to use them as a test runner, test assertions, test tagging, etc. These libraries are well-documented and have continued support. If you don't use these tools in e2e tests, what are you going to use?
Not all unit test tools are created equal. For example, if using Ruby, I would not use rspec for e2e tests. Mainly due to a lack of documentation and any feature updates that would support e2e tests.
Second, what do you mean by "framework?" Often, people conflate "framework," "library," "tool name," etc. The tools listed above are libraries that you use in order to create a framework of tests and test suites. "Framework" here is more about how you architect your solution, organize it, and tool selections.
In the end, you can use the same tools for both unit and e2e tests -- your implementation will be different.
Answer: Yes, I've done exactly that everywhere I've worked for the past 15 years, in Java, C#, and Python. There are some shortcomings using an xUnit style framework for e2e (system) tests, but the pros outweigh the cons.
(I'm assuming here that "framework" in this case means something like TestNG, Unit, Pytest, etc.)
Answer: Using a unit test framework for end-to-end (E2E) testing can be a good idea in some cases, but it may not always be the best choice. Unit test frameworks are typically designed for testing individual units of code, rather than the integration of multiple units and systems. As such, they may not offer all of the features that are needed for E2E testing, such as the ability to handle asynchronous actions or simulate user interactions.
That being said, if you are already familiar with a unit test framework and it provides the necessary features for your E2E tests, it may be a convenient choice. Using method annotations to trigger test execution can also be a useful way to organize and run your tests. However, it is important to carefully consider whether a unit test framework is the best fit for your E2E testing needs before proceeding.
Answer: No, it is not a good idea to use a unit test framework for end-to-end (E2E) testing. Unit tests and E2E tests serve different purposes and have different goals.
Unit tests are typically focused on testing individual units of code in isolation, such as individual functions, methods, or classes. They are usually fast, reliable, and repeatable, and are used to validate that the code is working as intended and catching any regressions early in the development process. Unit tests are usually written and executed by developers, and they are tightly integrated into the development process and the codebase.
E2E tests, on the other hand, are focused on testing the complete system or application, end-to-end, simulating real-world user scenarios and validating the integration and functionality of the different components and systems. E2E tests are typically slower, more fragile, and more complex than unit tests, and are used to validate the quality, reliability, and usability of the system before release. E2E tests are usually written and executed by QA teams, and they are typically executed less frequently than unit tests, for example, before releases or deployments.
Unit test frameworks, such as JUnit, NUnit, or TestNG, are not well-suited for E2E testing, as they do not provide the necessary abstraction, flexibility, or support for testing a complete system end-to-end. Instead, it is recommended to use E2E testing frameworks, such as Cypress, Selenium, or Puppeteer, which are specifically designed and optimized for E2E testing.
To conclude, while unit tests and E2E tests both play important roles in software development, it is not recommended to use a unit test framework for E2E testing, as they have different goals and requirements.
Answer: Unit tests :

Unit tests are intended to ensure code and methods are working as expected
Mostly developers implement unit tests

End to End testing :

E2E testing is something we are replicating exactly from start to end just like end user is going to perform in live or production environment
This is mostly carried out by QA members with positive and negative scenarios

Your question :

NO, we should not
Actually those two ways are definitely ensuring the quality somewhere but the objectives are different for both
Based on this understanding, we should not use Unit tests as E2E testing


How does HL7 format process ECG (digital) data

Question: Is HL7 format able to store(if in XML) and frame ECG data generated on a digital display ECG machine ? If yes, then how does it do it. Is it raw image data (BMP) or tags like XML ?
Any help welcome.
Thanks,
Xibee
Answer: I'm pretty late to the party but going to add my cents for future readers.
HL7 (for ecg) specifies a certain format in which to save ECG data during (for example) clinical trials in xml. This format is requested (AFAIK) by the FDA.
See this pdf on how to implement it. Read particularly page 34 about the node "sequenceSet" that contains the individual leads of the ECG you want to save. Note that sequenceSet/sequence number one does not contain your raw data but is used to determine how to interpret the future sequences!
That means if you have a regular 12 lead ECG, your xml should contain 13 sequences.
ECG Data themselfes are saved in the "digits" node of each sequence. Note that those should be short values and should match the duration and frequence of the measurement taken:
10 seconds measurment, increment unit "s" and increment value "0.001" should result in 10,000 digits per lead.
Comment: The implementation PDF has moved.  Updated link: [https://www.amps-llc.com/uploads/2017-12-7/aECG_Implementation_Guide.pdf](https://www.amps-llc.com/uploads/2017-12-7/aECG_Implementation_Guide.pdf)
Answer: ECG data is usually stored as raw waveform samples (A/D counts, probably in OBX segments), not images. There's no real standard, though, so each vendor will do it differently.
Answer: I am assuming you are using HL7 2.x since 3.x is based on XML and you should not have the question if you are using 3.x.
There aren't a lot of fields that are large enough to hold xml in HL7 2.x. Check if your message structure has OBX or NTE segment, you can put a lot of text in obx-5 or NTE. That is, up to your message receiver's limits. You can add multiple OBX/NTE segments if the text exceeds the size limit set by your message receiver.
You need to escape any HL7 control characters in your XML like you do for any other text field. However how to escape the control characters are up to your interface partner. I do not have experience with partners who follow the standard escape sequence.
You can base-64 encode any kind of binary data.
Answer: ECG images can be exchanged via DICOM.   It really depends on the ECG machine, and which formats it supports.  HL7 is not exactly intended for this purpose, but as mentioned you can base64 anything and stick in in a HL7 segment.
Mirth, a powerful open source HL7 interface engine, supports DICOM via dcm4che:
Answer: You can put any type of data on HL7 messages, either HL7 v2.x (ER7) or v3 (XML).


What is a person's consciousness in the next world?

Question: I have heard in the name of the baalei mussar that the same consciousness you have in this world carries through to the next. In other words the same "I" that you relate to in this world remains the same in the next world.
My question is if anyone has seen this idea talked about and if so where?
Thanks!
Comment: what else could it be? if there is no I how can there be any reward and punishment there?
Comment: @ray Maybe there is an I but not the same I as I identify with now.
Answer: Rachel still cries over her children which evokes divine pity. (yirmiyahu, 31:14)
MoShe's grave was hidden from us because he could still nullify evil decrees if we were able to alert him of them. (sotah, 14a, see the Bach's edit)
Yitzchak argues for our salvation where Abraham and yaakov say to blot us out, claiming that only 12.5 years of sin are present in a man's life that he is accountable for, and either Gd can take that on, he can split it with Gd, or Yitzchak can take all of it, since he offered himself to Gd. (shabbos 89b)
it seems that though there is not change available to a person after death, their personalities remain intact, as does their level of righteousness.
Answer: Here's 3 starting points:

Korach; even after going down to hell is still battling with Moshe's authority. He continuously yells משה אמת ותורתו אמת  - Moshe is true and his Torah is true and then adds ואנחנו בדאים - and we are liars - which some want to even interpret as meaning what I just said - about Moshe being true - is false.
In a similar vain, Chazal tell us that the wicked do not repent, even at the door to Gehinom.
The Gemora tells us that in the future the Evil Inclination will be publicly slaughtered, and both the wicked and the righteous will cry. The former because they perceive the it as a tiny hair they simply had to deal with. The latter because they see this huge mountain being slaughtered.
Comment: @Ariel, no, Danny was correctly citing the gemara in BT Sukkah 52a: the righteous will weep, saying: "How did we overcome this mountain?", while the wicked will weep, saying: "How were we unable to overcome this hair?" A beautiful teaching.
Comment: Did you get former and latter reversed, or is there a more subtle point I am not getting?


Prevent internal users from using production web-to-lead form to create test data in prod

Question: There are production users going to our company site and using our web-to-lead form to create data. This is a problem because there are times we don't know what are real leads, and which ones are tests. Is there anyway to lock the web-to-lead form down? Can we detect the I.P. address of who is submitting the form?
Answer: Sure, you could lock it down on your server. Your server knows the IP address of the visitor, so you could prevent it at the server level directly. Or, with a minor tweak, you could write an IP address to a hidden field in the web-to-lead form, and make a validation rule in Salesforce. Other options are also possible, but any solution you want to use will require updating the server code, not necessarily Salesforce. Also, keep in mind that Web-to-Lead can be used by anyone if there's an exposed org ID in the source code, so if you're going to do this, I suggest including some sort of additional validation in the form of a "magic value" that can be validated by Salesforce but can't easily be predicted by a person. Again, this needs either server or client-side code outside of Salesforce.


How does editing entries in cron file work?

Question: I have been trying to initialize a cron job programmatically with the help of JCrontab in Java. I have a cron file which i have given as the datasource to the job. At the start of my application, the Cron tab is up and running successfully. Let's say at some point of time because of an unexpected failure in my application, the cron file becomes empty. But before the next cycle of the job, the file gets filled with cron entries again. But i dont restart the crontab programmatically again. The job fails to continue in the next schedule. Why doesn't it get initialized automatically after watching the cron file get updated with the right data again?  How does crontab handle updating cron files?
Answer: man cron:

There are two ways how changes in crontables are checked.  The first method is checking the modtime of a file.  The second method is using the inotify  support.   Using  of  inotify  is  logged  in  the /var/log/cron log after the daemon is started.  The inotify support checks for changes in all crontables and accesses the hard disk only when a change is detected.

So the only possible reason for ignoring changes seems to be that the file's mtime is set back.


How to change sign text color in Minecraft?

Question: I have gone through every single website and video to try to make a sign with colored text, but nothing works. Can anyone help me to get a sign to say:

Place Block(dark blue and bold text)

I really want this for a map I am making and I need help.
Answer: What to use
It is common to use /blockdata for changing placed sign data. So, we will use it for now. The syntax of /blockdata is /blockdata [x] [y] [z] [dataInJSON] . Note that we use JSON formatting for text.
Basic for sign
To input a text with /blockdata, we will use Text1 tag. To write "Hello World" into the first line of the sign, simply just do /blockdata [x] [y] [z] {Text1:"{\"text\":\"Hello World\"}"}. The quotes is there for JSON formatting.
If you need multiple line to display, use either Text2, Text3 or Text4.
Coloring
There is a way to change color of the sign using the color sub tag. There is a lot selection of color. Here is all of the available one:

gold
red
dark_red
yellow
dark_purple
light_purple
aqua
dark_aqua
black
white
green
dark_green
blue
dark_blue

For writing "Hello World" in aqua, you write
/blockdata [x] [y] [z] {Text1:"{\"text\":\"Hello World\",\"color\":\"aqua\"}"}
into a command block. It will change the sign with the first line saying "Hello World" on aqua.
Bold
For bold text, you use bold sub-tag. This sub-tag is a boolean, meaning the value can be only true or false for example:
/blockdata [x] [y] [z] {Text1:"{\"text\":\"Hello World\",\"bold\":true}"}
will give you a sign with text "Hello World" with bold.
The real answer
Type this into a command block changing [x], [y], and [z] into the coords of the sign:
/blockdata [x] [y] [z] {Text1:"{\"text\":\"Place Block\",\"color\":\"dark_blue\",\"bold\":true}"}
Full list for Raw JSON tags
Comment: You can also use `/setblock` with the same NBT and JSON format. Note that it erases any existing text.
Answer: You can use /give command too.
by using the BlockEntityTag You can place a sign down with text.
for example if I wanted a sign with "RedIsCool" with red color I would have to do
/give @p sign 1 0 {BlockEntityTag:{Text2:"{\"text\":\"RedIsCool\",\"color\":\"red\"}"}}

in a command block, and then power it.
Answer: Version Update
1.12−
Above answers apply.
1.13
1.13 changed the command syntax. NBT now goes directly after the block/item ID, without a space. Here are some updated 1.13 commands from the previous answers:
/give @p sign{BlockEntityTag:{Text2:"{\"text\":\"RedIsCool\",\"color\":\"red\"}"}} 1
/setblock ~ ~ ~ sign{Text2:"{\"text\":\"RedIsCool\",\"color\":\"red\"}"}}

In addition, /blockdata is now a deprecated command, and has been replaced by /data merge block. Run the following command to change placed block data:
/data merge block ~ ~ ~ {Text1:"{\"text\":\"RedIsCool\",\"color\":\"red\"}"}

1.14+
The 1.13 commands still work in 1.14+, but additional modifications are possible to make the commands easier to read:

You can use /data modify instead of /data merge. This allows you to modify one specific tag at a time. This is more useful when performing complex operations with NBT tags, but isn't really needed for simple operations.

1.14 added support for single quotes ' to surround NBT string tags instead of double quotes ". Therefore, you can make the following replacement:
{Text1:"{\"text\":\"RedIsCool\",\"color\":\"red\"}"}
{Text1:'{"text":"RedIsCool","color":"red"}'}

which will make it much easier to read.
Comment: @Niekvb Hi, I noticed that you posted a new question related to this, and then followed-up with a self-answer. Are you still having problems?
Answer: It is example sign with custom text color:
/give @p oak_sign{BlockEntityTag:{Text1:'{"text":"Example","color":"#123456"}'}}

#123456 is your color hex. You can convert RGB to color hex with this website.
(RGB is Red Green Blue)


Is it possible to farm balthazar points in Guild Wars?

Question: Is it possible to farm balthazar points in Guild Wars? How? With a PvP or PvE character? I also read there is a limit of 2000 blthazar points. What exactly is the scope of this limit? And what is the best methode to win balthazar points once this 2000 limit is reached?
Comment: Possible dupe, http://gaming.stackexchange.com/questions/20069/what-are-the-deferents-possibilities-to-win-balthazar-points-in-guild-wars
Comment: best way to farm != possibilities to gain
Answer: You can go to Zaishen Elite and get a team of Trappers. Common builds and explainations can be found there: http://www.gwpvx.com/Build:Team_-_Balthazar_FFF_Zaishen_Trapper
But the cap is 6000 faction each day and every point gained from Zaishen Challange also counts against this cap!
AFAIK this is the fastest way to gain faction if you do NOT want to play straight PvP.
If you want more than these 6k/day just play Random Arena, Alliance Battles or Competitive Missions (Jade Quarry, Fort Aspenwood). With the corresponding Zaishen Battle quest a good amount can be gained.
See http://www.gwpvx.com/PvX_wiki for builds
Comment: This is the same response I put on the other question, so commenting that the questions are different and putting the same answers seems pointless.


avoke meaning by using other words' definition

Question: Can somebody write the   another definition to the word  avoke
other than:  call from or back again? [I can't understand this expression, can somebody explain to me the expression by another expression with a example to use the word]?
Comment: here did you encounter this word?. I don't think it's one that most native speakers are familiar with today. All the dictionaries I found listing it online mark it as "obsolete".
Comment: It is not a commonly used word today. Also, it is easy to confuse with "evoke", which means to bring something to mind
Comment: I can't find it in *any* dictionary!
Comment: This is not an English word that I have ever come across, and I am a native English speaker of almost 70 years.
Comment: Evoke? Revoke? Invoke?
Answer: I'm a Native speaker, and I do not recognise this word. I also agree that the definition is hard to understand. I finally got a clue from this related definition in WordSense
avocate (English)
Verb
avocate (third-person singular simple present avocates, present participle avocating, simple past and past participle avocated)
(obsolete) To call off or away; to withdraw; to transfer to another tribunal.

I am guessing that avoke relates to hunting with a pack of dogs. If we want the pack to stop chasing something we
call the pack off

if the pack has raced ahead of the hunting party we
call the pack back

So we
avoke the pack

I note that avocate has a legal meaning, to transfer a case to another tribunal. So an alternative guess is that avoke may mean to ask that a case be withdrawn from a court, we call the case back from the court.
I wish to avoke my case

I must emphasise that these are guesses. If you ever encounter a usage of the word then you may be able to infer the meaning more definitively. I don't advocate the use of avoke in your own speech or writing, I doubt that you will be understood.


trouble tinning tip

Question: I just bought a new tip (Weller ST7) for my soldering iron.  I've tried tinning the tip, but the solder just keeps forming a ball and then falling off onto the workbench.  What am I doing wrong?  (I never had any trouble with the old tip.)
Comment: Try a [tip tinner/cleaner](http://uk.farnell.com/multicore-loctite/ttc-lf/cleaner-tip-lead-free-15g/dp/1115477).
Comment: At what temperature are you using the tip? My personal preference is around 325 degrees Celcius. Clean the tip using one of these: http://img.photobucket.com/albums/v166/dc65x/Slot%20Blog-1/Toys/Hakko599b.jpg  (brass or steel wool).
Comment: There are tip temperature testers, those should be used to calibrate the temp readouts of the expensive stations. Also try and add some flux.
Comment: @Bimpelrekkie I have no idea.  My soldering iron has a scale of 1 to 5, and I set it on 3.5 when I solder.  That setting always worked fine with the old tip.  That's one thing I don't get about "how to solder" tutorials: they always talk about temperature, but only very expensive soldering irons have a temperature readout.  With a moderately priced iron, how do I know?  (My soldering iron is a [Weller WLC-100](https://smile.amazon.com/Weller-WLC100-40-Watt-Soldering-Station/dp/B000AS28UC/).)
Comment: @SteveG Thanks, I will get a tip tinner/cleaner and try it.
Answer: While having a temperature controlled soldering iron is always better, even a standard station like the Weller WLC-100 is more than adequate to perform soldering. There are some excellent suggestions in the comments but I wold also add that you really should use some additional flux. You can get No-Clean flux for general purpose usage or some RA/RMA flux if you work on corroded/exposed wires (i.e. point to point wires, guitar pickups, old electronics etc.)
Most good quality solder has flux inside it so you should double check your solder reel or the website of the manufacturer. If it doesn't have flux, you should get proper solder from Multicore, AIM, Kester or MG Chemicals. Avoid the cheap imitations available on some websites.
So use a tip cleaner as Steve G suggested, clean the tip regularly with a brass wire cleaner like @Bimpelrekkie suggests. Don't be afraid to add flux and make sure you have good quality solder wire.
Comment: Thanks, I have ordered a tip cleaner as suggested.  As for the solder, in this particular case I was using [this solder](https://www.adafruit.com/product/1886).  (I don't the brand they're reselling, but I trust Adafruit to have quality stuff.)  For thicker solder, I have some MG Chemicals solder that says "RA Flux" and "2.2% Flux".
Comment: @user31708 yeah, that solder is fine for hobbyist use. Just apply more flux when you solder and then clean the pcb with IPA or flux remover.

trouble tinning tip


Bolt dimensions for Peloton cleat

Question: I cant find this answer anywhere but what is the screw size of the Peloton sclip that goes onto the cleat?  I need a longer screw for my shoe but cant determine the thread size to make that determination.
Comment: I'm not sure about those cleats specifically, but most bolts on bikes are metric. It's most likely M5 just like any other cleat bolt.
Comment: Just to clarify, by "clip", I assume you mean the bolt that fixes the cleat to the shoe? Of which there are 3?
Comment: Your other option is to take a bolt from the other shoe, and go to a hardware store and look for a match.  Get spares too.
Comment: Yes it's the bolt that fastens it to the clear. M5 looks to big but I couldn't totally be wrong.
Comment: I wouldn't be surprised if Peloton had some custom shoe with odd-ball fitting that you have to buy.  If the shoe is a generic "3 bolt" shoe for road bolts then it will be a M5 x 0.8 standard thread form, which you can buy at any hardware store.  Or steal your waterbottle cage bolt.     If the "sclip" on the cleat is somehow different, please add a photo.
Answer: All 3-bolt shoe plates are M5 (5mm by 0.8mm per thread). So are 2-bolt. That's the thread size insofar as the wider world is concerned. That's not really what you care about.
What you ideally want is a Look Delta cleat bolt that's the right length for your shoe. They are funny little bolts and can be hard to find in just the right length if the stock ones aren't working for reasons like you're encountering. But, you need them to be low-profile like the stock ones are.

If you are forced to improvise from the hardware store or from what most bike shops will have, the best you can probably do is M5 button head bolts with large diameter washers. The total stack will probably be thicker than proper Look or clone bolts, so they may poke out or come close to it.
Comment: You can get bolts for road cleats of different lengths. Standard is 8mm but 10 and 13mm are available. Be careful though with bolts from hardware stores. The heads may be too high and catch in the pedal, making release impossible.
Comment: I was browsing McMaster-Carr. There's a listing for extra-wide flanged head bolts, with a 12.8mm flange diameter and a 3.2mm tall head. My SPD-SL bolts are a bit over 13mm wide, and its head appears to be not much more than 2mm tall. I'm going to guesstimate that a 3.2mm tall head would (just barely) be flush with my cleat surface. It seems possible that this might do in a pinch. https://www.mcmaster.com/bolts/thread-size~m5/rounded-head-screws/flanged-rounded-head-screws/

Bolt dimensions for Peloton cleat


Screen Recording in Quick Time 7 not available

Question: Just bought a new MacBook Pro 15" Retina display laptop with Maverick. Was needing to record an app on my screen. Went to Quick Time 7 and Quick Time 7 Player opened up. Registration for Pro was already set. How do you enable Screen Recording in Quick Time 7?
Comment: Quick Time 7 Player was in the Applications folder. After placing Quick Time 7 Player in the trash the Quick Time X was now available in the Applications folder. This is the first time i have ever ran across this as a solution
Answer: This is not a QuickTime 7 feature but a QuickTime X feature  !


Speed of a microprocessor

Question: I was just wondering why are are new generation microprocessors faster at the same clock speed as the old ones.
For instance a 2.66Ghz dual core i5 is faster than the a device with clock speed of 2.66Ghz but core 2 dual.
Comment: https://en.wikipedia.org/wiki/Megahertz_myth
Comment: https://en.wikipedia.org/wiki/Cycles_per_instruction, https://en.wikipedia.org/wiki/Instruction-level_parallelism, https://en.wikipedia.org/wiki/Superscalar_processor, etc.
Answer: If executing each instruction took a single clock-cycle, then your confusion would have been understandable, as a higher clock frequency would imply shorter cycle time, hence, more instructions per unit time.
However, the reality is quite different. Modern CPUs are usually pipelined, meaning that a single instruction takes multiple number or core-clocks, and that multiple instructions are executed simultaneously at the same time (each occupies different parts of the CPU pipeline). Complex instructions, such as calling a function or "jumping" to a different part of the code interfere with this pipeline and cause the CPU to temporarily halt its execution until the offensive instruction completes (known as a pipeline stall).
The picture is even more complex. Recent processors have multiple pipelines running on the same "core" (say, one clock advances pipeline 1 while the next clock advances pipeline 2). Of course, sometimes the program running on one pipeline affects (stalls) the progress of the other pipeline. This is "multithreading". Other approaches to make the CPU perform better are superscalar processing and other paralleling approaches.
As you can figure out, the number of instruction a CPU performs at any time unit is very complex to compute or even estimate, and is affected by the clock frequency, but also by the architecture of the CPU as well as by the program itself (e.g., how many "jumps" instructions it contains, or how well it parallelizes). All of these together determine the "speed" of the CPU, which is measured in the (average) number of instructions it can perform in a second, known as IPS. As said, the clock frequency is only one factor to the IPS, but in modern CPUs the specific architecture (rather than small differences in their clock frequency) dominates the IPS.
Answer: Modern x86/x64 CPUs are incredibly complicated. There can be dozens of instructions in various stages of execution flying around a CPU core at a given time. The cycle boundaries are just times when the various functional units synchronize with each other and work out what each one will be doing next.
A CPU can be made faster at the same clock rate by increasing the number of regions that can operate in parallel, increasing the amount they do per cycle, or increasing the fraction of time that they're actually in use. There can be tension between these approaches – e.g., increasing the number of execution units makes the chip larger, which increases travel-time delays, and you pay that penalty even if the code you're running doesn't have enough parallelism to use the extra units.
The gory details of how recent Intel processors differ from those of a decade ago can probably all be found in Agner Fog's optimization manuals, specifically the microarchitecture manual and instruction tables. They aren't really organized in a way to make comparing specific generations easy, but looking at the instruction tables for Wolfdale (45nm Core 2) and Ice/Tiger Lake, I see that many simple instructions have a throughput of 0.33 (i.e., three per cycle) on Wolfdale and 0.25 (four per cycle) on Ice/Tiger Lake, probably due to there being an additional execution unit that can handle them, and 128-by-64-bit integer divisions have a throughput of one per 10 cycles on Ice/Tiger Lake and one per 18-88 cycles on Wolfdale.
The microarchitecture manual says of Ice/Tiger Lake:

The pipeline is very similar to previous designs, but the number of execution units has been increased to improve the throughput from four to five instructions per clock cycle. The number of output ports is doubled so that the processor can do two memory reads and two memory writes per clock cycle under favorable circumstances. The size of the µop cache has been increased by 50%. [Wolfdale has no µop cache at all, though it has a small loop buffer which is a similar idea.] The resources for out-of-order execution have been increased further. The reorder buffer has 352 entries. [Wolfdale: 96] The reservation station has 160 entries. [Wolfdale: 32]

Ice/Tiger Lake also has 256-bit and 512-bit wide SIMD instructions, while Wolfdale only has 128-bit. This only benefits code that uses the new instructions, but a lot of software tests the CPU type at run time and uses new instructions when available, so a particular executable file may run faster on newer processors for this reason.
This is far from a complete list of changes and I encourage you to read Fog's manuals if you find this sort of thing interesting.
Answer: There are many techniques that can be applied.
At a higher level you have 2 main options:

ILP: Instruction Level Parallelism
TLP: Thread Level Parallelism

So increase parallelism in a single instruction stream or increase parallelism due to having multiple instruction streams.
Multicore (SMP) and hyperthreading (SMT) help to increase parallelism in multiple instruction streams.
Increasing parallelism in a single instruction stream can be done using:

pipelining
superscalar-execution/VLIW
SIMD instructions

What you see with the Apple M1 is that it deals very well with super scalar execution. So it has a huge out of order execution window so it can keep its execution units busy and it has many execution units. So instead of betting on higher frequencies, it bets on improved superscalar execution.
There are also other techniques that can be applied to speed up processors like increasing the size of the caches, branch prediction, prefetching, NUMA, etc.

Speed of a microprocessor


Ebola immunosupression and infection

Question: I was wondering... If Ebola attacks immune cells and causes immunosupression, then shouldn't we see death in Ebola patients due to secondary infection?
Comment: Secondary infections does not matter when you bleed to death... Btw. I hate this ebola hype, it is a relatively insignificant lethal virus, nothing more.
Answer: Yes, we should. But Ebola doesn't completely immunosuppress us, or there would be no survivors.
Ebola kills by overwhelming the body before enough antibodies are formed to fight it.
If you're one of the survivors (as about 40-50% are, more with good care), you'll have antibodies to Ebola in your blood which might help someone else infected with Ebola.
If you're not one of the survivors, it's still likely you'll have some antibodies, but the shock your body goes into from all the dead cell products in your blood (which - overly simplified - causes a cytokine storm -> leaky capillaries -> fluid balance problems -> end organ failure -> death).
Comment: So the Ebola virus replicates too fast for the immune system to handle?
Comment: I wouldn't quite put it that way. I'd say, rather, that in many cases, the host dies of the damage done by the virus before an immune response adequate to destroy the virus is mounted.

Ebola immunosupression and infection


Do different kind of waves in a medium interact with each other?

Question: Say for example, air and sound can both propagate to air. Now, suppose we have a sound and light wave travelling close by, how would the two waves interact with each other? Suppose I made a very large sound in the path of the ray, would that make any deviation in the motion?
Comment: Yes, one example being [acousto-optic modulators](https://www.rp-photonics.com/acousto_optic_modulators.html).
Comment: I would say yes but not for being waves. Simply the light would go through a modulated medium.
Answer: As mentioned in a comment above, there are also practical uses for interaction between electromagnetic and acoustic waves, particularly in piezoelectric materials. Acousto-optic modulators can shift beams by diffraction, and generate frequency shifts by mixing. These are often used in mode locking and Q-switching lasers.
There are also surface acoustic wave (SAW) devices that are used for oscillators, filters, delay lines and correlators at RF and microwave frequencies.
Answer: Air is made up of particles (atoms, gas molecules).  I know that's obvious, but am stating it as a starting point.  This means that the index of refraction of air depends on the density (and to a lesser extent on the percentage of each atom/molecule type in the mix).
Now, since the sound wave propogates by causing (or being) a sequence of compressions and rarefications of the atmosphere, there is a resultant pattern of changes in the index of refraction proportional to these pressure differences.  The light wave then is deflected according to Snell's Law as the air density changes.
At high optical power densities, the opposite is observable too: heating of the atmosphere caused by the photon interactions leads to pressure waves, i.e. sound.
Comment: the discontinuous change in the index of refraction of air passing a supersonic shock is strong enough to be photographed. The physicists working on the atomic bomb used this effect to follow the progress of the shock wave through the air surrounding a bomb blast.
Answer: Carl is right, and if you are flying at max cruise in a newer Boeing airliner and have a window seat on the wing you can actually see the index of refraction "kink" in the air above the wing's skin at about 2/3rds of the way back along the chord, where the air flowing over the wing goes locally supersonic for a bit.


Using CORS and Warden in rack app (Grape API)

Question: I have a Grape-based API running as a rack application, using rack-cors to allow cross-origin requests, and Warden for authentication. CORS is working as expected, but not in cases where I invoke env['warden'].authenticate. In these cases, I get an "origin not allowed" response.
I believe this is due to the order of the middleware, but I'm relatively new to rack applications. I found some information describing a similar problem with an example of how to make this work in Rails, by forcing the order of the middleware using config.middleware.insert_before Warden::Manager, Rack::Cors do ... but I don't know of a non-Rails equivalent.
The following is a simplified approximation of my config.ru:
require File.expand_path('../application', __FILE__)

use Warden::Manager do |manager|
  manager.default_strategies :password
end

use Rack::Cors do
    allow do
      origins '*'
      resource '/*', :headers => :any, :methods => [:get, :post, :options, :put]
    end
end

run application

I've tried swapping the order of the use directives, but either way I get same "origin not allowed" response from methods that use warden. Part of my problem is that I'm not clear on  what determines the order of the middleware in rack applications.
Is my hunch that the order of the middleware is causing this problem feasible? It seems like I'm missing something fundamental. I'd like to get rack-cors and Warden to play nicely or to find another solution to allow CORS. I tried explicitly sending the Access-Control-Allow-Origin header but Warden seems to wipe that out as well.
Answer: Had exactly the same (rather annoying) thingie, ended up with doing this on my one:
on a before do block,
header 'Access-Control-Allow-Origin', '*'
header 'Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT'

(You may want to tweak according to RACK_ENV or such...)
Seems to work. Note this is not a full CORS implementation(of course its not) but i'll wait for that rack-cors gem fix...
HTH
Comment: @Jatto_abdul in the controller
Comment: please where would this be set?


Question about Tezos flagged as off topic

Question: I'm not sure why this question was closed / flagged as off-topic. It's about the code architecture in Tezos. Would like to hear rationale or how it should have been phrased Test chain 48 hours constant
Answer: Questions about the design of a language, project, etc are off-topic for Stack Exchange sites. The question is asking for the reason behind part of the design of Tezos.
The close reason, however, is not very explanatory. The question is about Tezos, but is off-topic for a totally different reason. I submitted a custom close reason explaining why I was voting to close, but it did not end up being the chosen description.
Comment: unlike the design of a programming language, Tezos primary innovation is that it is self-amending. Meaning that the design will be constantly evolving. And it is the community of developers who will discuss, debate, and build in those design changes. With that in mind, it seems questions about the motivations about the existing design and especially proposed new designs are in fact very important for this community.
Comment: I +1 on @cousinit comment since indeed the voting feature of tezos is precisely asking all community to assess the reason why certain design choices were and whether it is time to have them evolve. Tezos was designed such that the system can respond meta-questions about itself (should we change inflation ? Why consensus should be implemented this way vs that way etc)


How to use GITHUB code in sharepoint?

Question: i need to create a mega-menu from a list in SharePoint online. as similar to the once below to my SharePoint. I have never used or tried to add GITHUB code sample to my SharePoint.
Please let me know how to use the code samples from GITHUB like the one below.
https://github.com/SharePoint/sp-dev-fx-extensions/tree/master/samples/react-mega-menu
https://github.com/SharePoint/sp-dev-fx-extensions
Answer: Just to be clear, the sample you are pointing to is using the SharePoint Term Store. And not a list as source.
You also need to use SPFx dev tools to complete that sample. Please have a look at this page for more information regarding SPFx development. https://docs.microsoft.com
You can download the repository as a zip using the method described in the image below:

One other way is to use GIT which is a way of version control your code. I like to use the SourceTree application for easy management of git repositories. SourceTree
Answer: In the link you provide, it tells how to use the examples.
You need to download files via clicking "Clone or Download" button. Then open CMD to navigate to the cloned repository folder, follow the steps.
Comment: CMD ? . Sounds really complicated.  I thought its a simple matter of downloading the code and editing it Visual studio to make it work. But it seems not the case. is there any step by step guide to use it.

How to use GITHUB code in sharepoint?


How to avoid out-of-disk-space on ramdisk?

Question: I am considering placing the tempdir of my MySQL database onto a ramdisk under Linux. The reason for this is to work around the 4 gb maximum of in-memory temporary tables in MySQL. My only worry is how to avoid out-of-disk-space errors if the MyISAM-based temporary table on the ramdisk would become bigger than the ramdisk? Could one some-how create a spill-over mechanism where the ramdisk size is the size of the ramdisk plus the free space on the harddisk. If the ramdisk would become full, the rest would be written to the harddisk.
Comment: @JohnGardeniers A search for TARDIS ramdisk got me nowhere. Do you have anything else to search for?
Comment: You want a ramdisk to be the size it is plus the free space of the hard disk? You need a TARDIS ramdisk for that.
Comment: @David Try dropping `ramdisk` from your search. And yes, the first wikipedia result is relevant.
Answer: Think about this logically and ignore the fact that it's a RAM-backed virtual disk: You are asking for a disk device that gets bigger because you tried to store more stuff on it.
You are asking for a blessed +30 bag of holding.
You are asking for a Dimensional Hole.
You are asking for a TARDIS ("It's bigger on the inside").
You are asking for something that doesn't exist. At least not as far as I've ever seen...

Using tmpfs/RAM-backed storage for temporary tables is a very elegant way to get around the 4GB limit.  Be aware though that the RAM you lock up won't be available for MySQL to do stuff like SORTing, JOINing, etc. so you're going to need GOBS of RAM to make this practical - you need the tmpfs to be big enough to hold as many temp tables (of presumably substantial size) as you'll need at any one time, and you need to still have enough RAM left over that you won't wind up swapping when you run big queries (otherwise your performance will go down the tubes anyway because SOMETHING is gonna have to be swapped in and out!).
A more practical solution may be to cleverly craft explicit (and efficient) JOINs that eliminate the need for temporary tables (if possible), and saving them as views.  Without knowing more about your environment I can't give you specific guidance, but you can always ask on the DBA site with some basic details about what you're doing and see if they have suggestions...
(I'm sorry to be the bearer of bad news, but if it's worth anything I did have fun typing this answer.)
Comment: +1 for the honesty about a fun time answering
Comment: Add to that Phantasia's self-replicating brooms and the universal NanoTech Grey Goo
Comment: will the brooms clean my apartment?
Answer: In theory I guess you could create a JBOD filesystem using physical volumes from the ramdisk and the hard disk - but I'm not sure if it would automatically fill up the ram disk first. This doc might shine a bit more light on the topic
Comment: You can probably do some black magic with volume management to create a RAID 0 and always fill "disk 0" first, but you'd need to map RAM as a raw disk device instead of a tmpfs partition (do-able), and you'd probably have Badness on reboot (physical disk has LVM metadata, newly-created empty RAM "disk" is blank or randomized) - seems kinda dirty & begging for trouble later on...
Answer: Your best bet is just purchase a 64GB SSD and put your tempdir on it and nothing else. They are cheap ones about $1/GB (on sale) so for ~$64 and $2 a GB not on sale, you could have a super fast tempdir that you don't have to worry about being to small.