Is it better to use an uniqueidentifier(GUID) or a bigint for an identity column?

Question: For SQL server is it better to use an uniqueidentifier(GUID) or a bigint for an identity column?
Comment: Did you mean primary key? You can't have a GUID identity column.
Comment: Jeff Atwood has already answered everything [in this comprehensive post](http://blog.codinghorror.com/primary-keys-ids-versus-guids/).
Answer: That depends on what you're doing:

If speed is the primary concern then a plain old int is probably big enough.
If you really will have more than 2 billion (with a B ;) ) records, then use bigint or a sequential guid.
If you need to be able to easily synchronize with records created remotely, then Guid is really great.

Update
Some additional (less-obvious) notes on Guids:

They can be hard on indexes, and that cuts to the core of database performance
You can use sequential guids to get back some of the indexing performance, but give up some of the randomness used in point two.
Guids can be hard to debug by hand (where id='xxx-xxx-xxxxx'), but you get some of that back via sequential guids as well (where id='xxx-xxx' + '123').
For the same reason, Guids can make ID-based security attacks more difficult- but not impossible. (You can't just type 'http://example.com?userid=xxxx' and expect to get a result for someone else's account).
Comment: I wouldn't think that GUIDs would be that much faster in a join... modern processors deal with numbers 32 or 64 bits at a time.
Comment: Wouldn't that be 2 billion rows? INT is signed.
Comment: ;) Okay... I'll take off my -1
Comment: @AndrewRollings, "Wouldn't that be 2 billion rows?" - no, "INT is signed." - it doesn't change anything. Hint: `id int identity(-2147483648, 1)`. It's 4 bytes long and it gives 4+ billion different values.
Comment: Even if the id is an int, I would use an additional guid column to provide a lookup for use with URLs... Either that or an additional correlating parameter to prevent that kind of attack.
Comment: Why would you give results for some else's account event if they give the correct ID?
Answer: In general I'd recommend a BIGINT over a GUID (as guids are big and slow), but the question is, do you even need that? (I.e. are you doing replication?)
If you're expecting less than 2 billion rows, the traditional INT will be fine.
Answer: Are you doing replication or do you have sales people who run disconnected databses that need to merge, use a GUID. Otherwise I'd go for an int or bigint. They are far easier to deal with in the long run.
Answer: Depends no what you need.  DB Performance would gain from integer while GUIDs are useful for replication and not requiring to hear back from DB what identity has been created, i.e. code could create GUID identity before inserting into row.
Answer: If you're planning on using merge replication then a ROWGUIDCOL is beneficial to performance (see here for info). Otherwise we need more info about what your definition of 'better' is; better for what?
Answer: Unless you have a real need for a GUID, such as being able to generate keys anywhere and not just on the server, then I would stick with using INTEGER-based keys.  GUIDs are expensive to create and make it harder to actually look at the data.  Plus, have you ever tried to type a GUID in an SQL query?  It's painful!
Comment: No one tries to type a GUID. I am sure copy/paste was invented the day after GUID's were invented ;-)
Answer: There can be few more aspects or requirements to use GUID.

If the primary key is of any numeric type (Int, BigInt or any other), then either you need to make it Identity column, or you need to check the last saved value in the table.
And in that case, if the record in foreign table is saved as transaction, then it would be difficult to get the last identity value of primary key. Like if IDENT_CURRENT is used, then will be again effect performance while saving record in foreign key.
So in case of saving the records as for transactions, then it would be convenient to firstly generate Guid for primary key, and then save the generated key (Guid) in primary and foreign table(s).
Answer: It really depends on whether or not the information coming in is somehow sequential.  I highly recommend for things such as users that a GUID might be better.  But for sequential data, such as orders or other things that need to be easily sortable that a bigint may well be a better solution as it will be indexed and provide fast sorting without the cost of another index.
Comment: You can use NEWSEQUENTIALID() to create sequential GUID field which make the index more optimized and improve performance.
Answer: It really depends whether you're expecting to have replication in the picture.  Replication requires a row UUID, so if you're planning on doing that you may as well do it up front.
Answer: I'm with Andrew Rollings.
Now you could argue space efficiency. An int is what, 8 bytes max? A guid is going to much longer.
But I have two main reasons for preference: readability and access time. Numbers are easier for me than GUIDs (since I can always find the next/previous record easily).
As for access time, note that some DBs can start to have BIG problems with GUIDs. I know this is the case with MySQL (MySQL InnoDB Primary Key Choice: GUID/UUID vs Integer Insert Performance). This may not be much of a problem with SQL Server, but it's something to watch out for.
I'd say stick with INT or BIGINT. The only time I would think you'd want the GUID is when you are going to give them out and don't want people to be able to guess the IDs of other records for security reasons.


Can I bring my desktop computer as check-in baggage on a flight?

Question: I am moving from Malaysia to the US, and planning to bring my desktop computer with me. I plan to pack it in my checked-in luggage. Will the computer risk being damaged? Any precaution should I take to reduce this risk? Will there be any trouble with the airline or immigration about bringing computer?
Comment: There appears to be a confusion here. Do you want to bring a CPU unit or a computer?
Comment: While it is likely possible one would have to question the wisdom of doing it
Comment: Related question about a desktop as checked luggage: http://travel.stackexchange.com/q/3748/324
Comment: @MohdSaif there's other alternatives, like sending it through UPS or FedEx, or as airfreight.
Comment: @Karlson the alternative is buying a new one in the destination. Which is quite expensive
Comment: @mohdsaif Unless you have a really high end desktop it may not be as expensive.  BTW what are you planning to do for a monitor?
Comment: @Karlson For a monitor, I'll see whether I can pack it too. But the computer is more important. Even if it only cost a few hundred dollars, I think the trouble of packing it is still more preferred than having to spend another couple of hundreds
Comment: @MohdSaif You can buy a computer for $300 http://www.dell.com/us/p/inspiron-660s/pd?oc=fddwsp32&model_id=inspiron-660s
Comment: You have some good answers already so i'm just going to comment. From personal experience I brought my PS4 to the USA from the UK in my hand luggage no problem when i was staying in the USA for a few months
Answer: There's no problem with doing this.  However, a couple of things I'd consider doing to protect it:

you've not specified if it's a laptop or a desktop.  If it's a desktop, I'd remove the hard-drive and take that carry-on.  It's 5 minutes to do, and it's arguably the most valuable part of your computer.
if it's a laptop, I'd remove the battery - still pack both, just keep them separate.  Means the laptop won't be on, and not that I can imagine anything happening - but at least it means nothing is even on standby power in your luggage.
wrap it in clothes.  This will help protect it from the luggage guys tossing your bag around or whatever might happen behind the scenes.
some people suggest adding a fragile sticker to your bag, but I've also heard varying reports over whether that is taken notice of at all.
my friend who took a desktop from London to Australia bought a hardened shell-case luggage to carry it in, just to be sure.  He also removed the hard drive first.

The airline should have no problem at all. I've done this myself with many airlines, and I'm sure many people do it every day. It's only if you take it as carry-on that they'll want you to take it out of your bag for extra screening.  If however you want to be certain, check with the check-in agent at the desk, but they'll be fine with it, I'm sure.
Comment: It is a desktop. "I've done this myself with many airlines" -> have you done it with desktop?
Comment: @KateGregory I spend a lot of time at airports, I see with my own eyes how luggage gets treated, and it ain't pretty. It's indeed tossed around, but worse there's quite a lot of luggage falling from heights onto the tarmac, sometimes getting driven over by trucks or other vehicles, etc. etc. And then there's luggage theft, which is the main reason airlines tell you not to pack valuables.
Comment: No not with a desktop, but a NZ friend of mine did from London to Australia - he removed the harddrive but travelled with the rest.  Bought a case for it...ooh I might add that to my answer.
Comment: despite all the nasty things people say about luggage being tossed etc, it holds up pretty well. I've brought a screen in my checked luggage (long story) and it survived just fine. I wrapped it in my clothes. There might have also been bubble wrap involved.
Comment: did your friend's computer arrived safely? May I know which airline was it?
Comment: (cough) [Relevant](http://travel.stackexchange.com/questions/3220/why-would-you-wrap-your-luggage-in-plastic)
Comment: so your friend's computer was not damaged?
Comment: Nope, he put the harddrive back in in Sydney, and it's still working now (18 months on).  No problems at all.
Answer: In general, you can bring a desktop computer as checkin baggage, even on international flights, but there is a risk of damage you should consider. They tend to be so commonplace of a device that are well-recognized and tend not to arouse suspicion.
Anecdotally, I was part of a group trip to Costa Rica (from the US) where we brought approximately 30-40 used desktop computers, complete with old fashioned glass CRT monitors as checked luggage to donate to worthwhile organizations in Costa Rica. Of those, approximately 5-6 computers were damaged and a slightly higher percent of the monitors. The computers were wrapped in a couple layers of bubble wrap (the kind for with the larger 1"/2cm bubbles), inside a soft shell duffel bag, probably not as ideally wrapped as I would wrap my own personally computer. So, if my experience is in any way typical, odds are good, but far from perfect, that your PC will arrive undamaged. Most of the time, luggage will arrive in good condition, however, luggage could get dropped or fall off a baggage cart, for example, and even well packed, there's a risk of damage.
Providing adequate packaging, such as the original computer's box with styrofoam inserts, is one of the best ways to minimize damage. New PCs are shipped to their destination in such packaging all the time without incident. Keep in mind, depending on the baggage policies of your airline, there may or may not be restrictions on using cardboard boxes as checked luggage. If there are prohibitions, placing the entire box in an inexpensive large soft-sided duffel bag with handles will usually suffice. Alternately, a hard-shelled suitcase, filled with foam or other absorbent material (preferably ESD foam) around the PC would be the next-best alternative. Keep in mind your packaging may need to be opened if your bag or box is randomly selected for additional screening, so don't make the packaging so intricate or complex or not-resealable that a luggage inspector would not be able to put the protective packaging back how you intend if it is subjected to additional screening. If they do have to cut packing tape, typically that is replaced with new packing tape by the screeners. Zip ties on the other hand, for example, are not replaced if cut by screeners.
The most likely component to suffer damage from rough handling is your hard drive, especially if you have a typical desktop computer hard drive in your computer. Desktop computer hard drives are significantly more fragile than laptop hard drives, and can be damaged by jostling and impact, making the entire drive unreadable. So possible improvements could vary from replacing your 3 1/2" hard drive with a 2 1/2" laptop hard drive (and using conversion rails or a mounting kit to attach the hard drive in your case), to replacing a standard hard drive with a solid state hard drive (bonus points: they're super fast), or backing up any/all critical files to a recovery medium such as DVD or USB flash drive or internet location, such that you could restore your data should your hard drive become damaged from the journey. Carrying the hard drive as a carry-on item (as suggested by Mark Mayo) is not a bad idea and reduces the risk of someone other than yourself handling the item roughly, but keep in mind that a typical non-solid state desktop hard drive is still rather delicate and there is a risk you'll go to plug it back in and it just...won't work. So absolutely bring back ups of your data, or back up important data online somewhere before your trip.
It is possible some other component of the computer (motherboard, video card, etc). could get damaged from the entire case being dropped, so if that were to happen you might have to replace something (or several parts), but that is slightly less common than hard drive damage.
Make sure everything in the PC is seated securely, screwed in, and there are no loose wires hanging precariously or loosely. Excess lengths of cables should be replaced, bundled or tied to mounts in the case or otherwise secured so that they will not be bumping into other components inside the case. Your whole PC could be carried upside down or sideways leading to things bumping where they wouldn't normally on your desk.
Additionally, to minimize the risk of damage from electro-static discharge (ESD), wrapping the entire PC in a large ESD bag or ESD foam would be another precaution you could take. Consider that brand new hard drives and motherboards are almost always wrapped in such a protective container before being shipped to stores.
Comment: Nice answer. I agree on packaging each component on its own: this is easy for someone with some experience maybe excepting CPU because of thermal paste. In addition, I would also consider about not including the case, especially if you don't have too much space, or at least fill in the remaining space with bubble wrap. Althought each component is fixed at the beginning, one of them can be released and damage the other ones.
Comment: Well, I read it again and maybe I misunderstood you and you don't talk about packaging each component on its own. With "original CPU's box" you mean the whole case or just the CPU (processor)?

Anyway I still recommend disassemble it.
Comment: I think he just means PC instead of CPU.
Answer: You can pack your computer as a checked bag, Mark Mayo's answer covers how to do so pretty well.
But I would highly recommend against packing a desktop computer. With all the wires and whatnot it will look "suspicious" to security personnel, and they'll almost certainly go through your bag (likely not repacking it with any care).
I would recommend shipping the computer to the destination, even a service as simple as the postal system. It will undoubtedly take longer to arrive, but if properly packed will arrive in tact.
I've worked with computers for half of my life. Shipping has never failed me yet. Overzealous security personnel, well I've got a few stories about them already...
Comment: "likely not repacking it with care" Yep!  My story: Laptop in laptop bag, wrapped in towels and clothing, placed in the exact center of bag (clothing on all six sides). Cinch straps all pulled tight so nothing can move and loose ends tucked into loops on the outside of the bag. At bag claim, all straps were untucked, loosened to full length, some unhooked, and the laptop was on top of everything, the wrappings removed and stuffed into a corner.  Another time I saw a handler, instead of sliding a bag onto a belt through a hole designed for such, tossed it over a meter high railing.
Comment: Also, some peripherals had been removed from their padding and returned to the bag loose.
Comment: any idea about shipping companies that will do this, or how much it normally cost?
Comment: Shipping would depend on the size and weight of your computer. I'd venture a guess that it'll be about 100-150 MYR. I added you to [chat], so you can join now.
Comment: Sorry, but this answer is wrong.  I've traveled with desktop computers as checked luggage several times (both international and domestic in several countries) and never had a problem.  Security will know *exactly* what is in the box, and a few "wires and whatnot" will not in itself cause them to even consider inspecting the item.
Answer: I successfully did this with my desktop, on a lengthy international flight (transfers, etc).  Here's what I did, and how it worked.:

Remove all the components (barebones level).  The only thing I
left in my tower case was the motherboard, PSU, and CPU (left in the
socket, but heatsink removed).  Rationale is to minimize damage from jostling, torque, inspection, etc.
Take the components in the carry-on.  Memory, graphics cards, HDD
esp.  All came with me in bubble wrap.
Make it easy for TSA/luggage inspectors to open up your case.
Remove the side panels, or unscrew them and label as to how to
remove.  Open any drive bay covers.  I made the mistake of leaving
my heatsink in the empty space near my drive bays, and the TSA
inspectors didn't know how to access it, so they snapped parts of
nearly all of the covers to reach it.  From the inspectors
perspective, anything with wires = dangerous (PSU, fans), so make
those parts easy to reach.  Remove if possible and individually
pack.
Protect the motherboard and case.  I put some cardboard and a solid
block of styrofoam over my motherboard, and packed the rest of area
with other luggage, etc, clothes.  The tower barely fit into my
checked baggage, and was secured by the rest of my luggage packed
tightly aroud it.
I also took dual 24" monitors in the other checked bag.  They were surrounded by thick (>1 inch) foam on either end and between each other.  Monitors were themselves also wrapped in plastic (to keep screen from being scratched).  This bag was not opened by TSA, so can't speak to how well it would have been re-packed if it was opened.

I used a soft case luggage for both desktop and monitors, but hard shell would of course be better.
Answer: I did that myself, I brought my desktop from Brazil to the US with a regular luggage but packed with clothes, some bubble wrap wrapped around in a way that nothing inside would ever move and I'm doing it again but from the US to BR again, but this time with a different luggage, one with the hard shell thing. Looks safer, but be sure to fill everything so nothing moves.
Answer: I know the question is for checking-in the PC as luggage. I would however suggest bringing it as a carry-on because you reduce the risk of physical damage. This is only possible if your case fits the carry-on size limits. Some tips:

Isolate your fragile parts by removing them from your case (I didn't and everything survived)
Put your case in a cardboard box (with padding if there's space). This makes it easier to carry and less "suspicious".
Have some sort of handle/strap to make it easier to carry (for queues)

I've done this myself in 2017 (flown from US to Canada, and from Canada to the UK) with no issues whatsoever. It was easy since I have a mini-ITX case.


"Broadcast" or "broadcasted"

Question: I'm not a native English speaker, so sorry if this is a very basic question. Is broadcast a verb? If it is, what is the simple past and past participle: broadcasted?
Comment: Good question.  I've heard both "broadcast" and "broadcasted" being used for the past tense of the verb.
Answer: Yes, broadcast is a verb, and Dictionary.com says either broadcast or broadcasted is acceptable as the simple past and past participle.
However, this Ngram shows that broadcast is by far the preferred version.

A study on this very issue can be found here.
Comment: @DrOtka - Any native speaker of English has an intuitive understanding of the use of the "-ed" suffix, so there is no way they could *not* be aware of that option.
Comment: Besides the words mentioned in the article, I think that this little quirk also applies to _telecast_. But it curiously does not seem to have the same effect on _forecast_.
Comment: -1 for stating that broadcast is the "preferred version". To be aware that you are using a word and prefering it requires you to be aware of at least one more option. Not everyone can be said to have preferred the use of "broadcast" to "broadcasted".

"Broadcast" or "broadcasted"


Receive notifications on all answers, comments and new questions for a tag

Question: I'm interested in receiving notifications for all new questions, all answers and all comments for a given tag. So, if a new question is added with a given tag, receive notification (I think that works already), but I also want to receive notifications whenever an answer or a comment is made on a question with a given tag. How do you achieve this?
Comment: You know that it means thousands of daily notifications for tags like [tag:C#]?
Comment: Clearly, it should be something that can opt to. As you can imagine, in my case this is small/new tag.
Comment: While this is a good idea for smaller/newer tags; it is pretty annoying with [tag:php] or [tag:c#].
Comment: The relatively recent ability to [follow a post](https://meta.stackexchange.com/q/345661/986753) may be a useful alternative, especially if the tag is small.
Answer: You can watch a tag. Watching a tag will highlight questions with that tag in question lists, though you won't be automatically notified of any new activity in the tag. Here's what you will see when you hover your cursor over a tag:

If you want to get a little fancy, you can grab the RSS link from that popup (the little orange symbol in the top right corner of the tag summary box), and put it into an IFTTT recipe that can send you a text or change the colors of your light-bulbs or something for every new tag question.
I don't know if there is any feature that will send you a notification for every new answer or comment though; that's a little too much information, anyway, IMHO.
Comment: Well answer isn't wrong now, but also does not give real answer, SE simply removed the option to get email notifications for single tag. (There is "Filtered Questions" on se.com but it's way more complex than what we used to have)


Is it bad to run a 1000rpm rated 12V DC motor at lower rpm?

Question: I'm trying to make a rock tumbler. The 12V DC motor I have is rated for 1000rpm. Can I run it at lower rpm without harming the motor? I'm planning to use an Arduino and motor controller for the project.
Answer: Running the motor slower is OK.  The main limitation of how a motor is run is due to the heat it produces.  This heat is from the DC resistance of the windings carrying current.
The heat is therefore proportional to the square of the current. Since the motor torque is proportional to the current, you must be running the motor at a lower current to get the slower speed.
The above assumes that the mechanical load on the motor is no greater at the lower speed than at full speed.  The motor must also be able to generate enough torque to get moving from a standstill.  If it isn't allowed to move, and full voltae is applied, it can get too hot.


How to set user profile Id in a trigger test

Question: I am writing a trigger test class for a trigger that inserts a new task when the current task is saved. In the trigger I only want it to fire when the current user has a certain profile. Because of this, I am unable to get past that validation in testing since I am logged in as system administrator. is there a way to bypass this in the trigger test code?
Answer: There is this example in the Using the runAs Method documentation that shows how to switch profile in a test:
<code>@isTest
private class TestRunAs {

    @isTest
    static void testTriggerUsingRunAs() {

        // Create a unique UserName
        String uniqueUserName = 'user' + DateTime.now().getTime() + '@org.com';

        // Pick the Profile you want to test under here
        String profileName = 'Standard User';
        Profile p = [SELECT Id FROM Profile WHERE Name = :profileName];

        // Create a User object that uses that Profile
        User u = new User(
            UserName = uniqueUserName,
            ProfileId = p.Id,
            Alias = 'standt',
            Email = 'email@example.com',
            EmailEncodingKey = 'UTF-8',
            LastName = 'Testing',
            LanguageLocaleKey = 'en_US',
            LocaleSidKey = 'en_US',
            TimeZoneSidKey = 'America/Los_Angeles'
        );

        System.runAs(u) {
            // Add your trigger test code here
            System.debug('Current User: ' + UserInfo.getUserName());
            System.debug('Current Profile: ' + UserInfo.getProfileId());
        }
    }
}
</code>
(I've changed this a bit for the context of your question.)
Comment: Amazing, thank you.


What are the reasons why the Federal Reserve won't make public the transcripts of its meetings?

Question: Is there a reason why the Federal Reserve won't make public the transcripts of its meetings? They officially gave the explanation that making the transcripts public would negatively impact troubled lenders, but why won't they make transcripts public after say 10 years to avoid that from happening? How does the Federal Reserve differ from other central banks, and are there other reasons for the lack of transparency?
Comment: Are other important Central Banks make their proceedings public? If not the question could be generalized a bit.
Comment: Someone on econ.se said at one point that they do make the public after 5 years, but I haven't checked the accuracy of that claim.
Answer: You are under a misconception.  The Federal Reserve, specifically the Federal Open Market Committee, makes transcripts and minutes both available, with small redaction.

Transcripts
The most detailed record of FOMC meeting proceedings is the transcript. Beginning with the 1994 meetings, the FOMC Secretariat has produced the transcripts shortly after each meeting from an audio recording of the proceedings, lightly editing the speakers' original words, where necessary, to facilitate the reader's understanding. Meeting participants are given an opportunity within the subsequent several weeks to review the transcript for accuracy.
  ...
In transcripts from all years, a very small amount of information received on a confidential basis from, or about, foreign officials, businesses, and persons that are identified or identifiable was subject to deletion. All deleted passages, indicated by gaps in the text, are exempt from disclosure under applicable provisions of the Freedom of Information Act.

...

Minutes (Current)
  The minutes of each regularly scheduled meeting of the Committee provide a timely summary of significant policy issues addressed by meeting participants. The minutes record all decisions taken by the Committee with respect to these policy issues and explain the reasoning behind these decisions. From their emergence in their present form in February 1993 until December 2004, the minutes were published approximately three days after the Committee's subsequent meeting. In December 2004, the Committee decided to expedite the release of its minutes. Since then, the minutes have been made available to the public three weeks after the date of the policy decision, thus reducing the lag in their release by an average of about three weeks. The minutes are subsequently published in the Board's Annual Report.

In this article you can see reporting about minutes being distributed shortly after the meeting.

If the Federal Reserve's Federal Open Market Committee decision on interest rates at the end of July wasn't strong enough, there is another chance to evaluate the same data from that time all over again. The Federal Reserve has released the minutes of the FOMC meeting and the interpretation that Jerome Powell's "mid-cycle adjustment" may not have addressed some of the actual concerns that were in the room.

Now some of the CCAR or stress testing meeting contents may be kept confidential.  Maybe that's what you were thinking of. The results of those tests are published annually.  But not internal meetings on the same as far as I know.


Can a person be put on probation without being convicted of a crime?

Question: Can a person be put on probation without being convicted of any kind of crime? While in court for the accusation of a crime.
Comment: Where? The law and legal terminology are not uniform in every country and law making jurisdiction.
Answer: canada
No. The word "probation" is used only to refer to a type of sentence imposed after conviction.
However, when a person is not yet convicted, they may be released. For most offences, the default is that the person must be released without conditions unless the Crown (prosecution) shows detention or conditiond are necessary.
This release is known under various terms:

judicial interim release
pre-trial release
bail

The conditions (if any) that are imposed during pre-trial release are often similar to conditions that can be imposed during probation.
Answer: Probation is the situation where fines and imprisonment following from a conviction are suspended. A typical shoplifting probation sentence has the defendant plead guilty or nolo contendere, then after the requisite period has passed with no intervening arrests the conviction can be vacated and the record expunged. It is not possible for a judge to declare a person guilty without a trial or their pleading guilty.
Comment: Deferred prosecution exists in some jurisdictions and while not technically probation, it would be hard for a lay person to distinguish it from probation.


"from far away" and "from afar" do they have different nuances?

Question: I have seen the phrase " from afar" more frequently than "from far away." like in "He walked from afar." I just think it might be because the former has a bit of poem like. What do you think? Do the both have the same meaning, and can they be used in the same way? Please answer my question.
Answer: It's not a black-and-white difference in meaning, but, from afar usually implies movement (he came from afar), where from far away would describe an action taken while staying far away (we heard his voice from far away).
Hopefully someone can remind me if there is a grammaticistal term or explanation, all I can think of is … context? connotation?
Comment: It would be fun to see a list of usage even from maligned Google Books / ngrams
Comment: I just did a quick look at ngrams and saw that both far away and afar are dominated by verbs come and see—but that doesn't mean they aren;t used differently after their most common verbs
Comment: *Come from far away* implies *were born in another country* more than *have just arrived from a distance*, though that's really more of a convention.


On order page in action tab want to delete button

Question: In the Sales>Order page on the right side, there is the drop-down option for Actions. In that actions tab, there is the delete option and I want to hide this option from that page. Anyone know how to hide this? Thanks.
Comment: Hi. In default magento there are no delete option exist for sales>order>Actions tab. I think it arrives from any third party extension. You have installed any third party extension?
Answer: In the default Magento "Delete order" feature is not available. There will be some extension or custom code for this.
So follow this steps to find if any extension for this:

Go to Magento directory in app/code there will be directories local and community. Inside this directories check any delete order extension.
if an extension is there like company/deleteorder then go to app/etc/modules and edit XML file for that module for example company_deleteorder.xml.
And change the active tag to false.
Flush cache and check


Allow single login per account - CouchDB

Question: I want to ensure that the user is logged in only one device at any given point of time. Just like the banks do it. How can this be ensured and implemented in the CouchDB Authentication suite?
Answer: If I've understood correctly, this cannot be achieved out-of-the-box with CouchDB.  In CouchDB version 2.0, the only authentication mechanisms supported are:

HTTP basic authentication
cookies

Basic authentication
As each request is authenticated separately with this scheme, it's meaningless to think of a user as being "logged in".
Cookies
CouchDB does not keep track of cookies that it has issued.  This means that it has no knowledge of open/active sessions that exist.  For this reason, it would have no way of restricting the number of active sessions for a particular user.
Answer: The only way to accomplish this would be to use a proxy server in front of CouchDB, along with proxy authentication.  It would be the responsibility of your proxy server to enforce whatever limits you desire.


Terraform resource github_repository_webhook requires GitHub organization to be set on the provider

Question: I am Making a CI/CD pipeline with terraform AWS. This pipeline works 100 percent perfect if I don't configure webhooks rather than goes with default option i.e AWS CodePipeline which periodically checks for changes in github.
When I configure webhooks for my pipeline to make it start automatically on every push. I am getting below error which is at the end after the code. I understand one solution that is "if I make an organization and set individual=false in my providers settings" it will work.
But I don't want to make an organization rather wants to work with individual = true. Is there any way by which I can solve this problem?
P.S: I added only those files in this question which are related to my problem. If you want me to add my whole code please request revision
Filename: Provider.tf
provider "aws" {
  region  = var.aws_region
  version = "2.55"

}

provider "github" {
  token      = var.github_token
  individual = true
}

terraform {
  backend "s3" {
    key    = "ecs_fargate/infrastructure.tfstate"
    bucket = "umartahir-terraform-buckettestus-east-1"
    region = "us-east-1"
  }

}

Filename: Codepipeline.tf
#Code Pipeline
resource "aws_codepipeline" "codepipeline" {
  name     = var.pipeline_name
  role_arn = aws_iam_role.codepipeline_role.arn

  artifact_store {
    location = var.bucket_for_codepipeline
    type     = var.artifact_store_type
  }

  stage {
    name = "Source"

    action {
      name             = "Source"
      category         = "Source"
      owner            = var.source_stage_owner
      provider         = var.source_stage_provider
      version          = "1"
      output_artifacts = var.source_stage_output_artifact_name

      configuration = {
        PollForSourceChanges = false
        OAuthToken           = var.github_token
        Owner                = var.git_hub_owner
        Repo                 = var.repo_name
        Branch               = var.branch_name
      }
    }
  }

  stage {
    name = "Build"

    action {
      name             = "Build"
      category         = "Build"
      owner            = "AWS"
      provider         = "CodeBuild"
      input_artifacts  = var.source_stage_output_artifact_name
      output_artifacts = ["build_output"]
      version          = "1"

      configuration = {
        ProjectName = aws_codebuild_project.code_build_stage_pipeline.name
      }
    }
  }
}

# See this in detail later

# A shared secret between GitHub and AWS that allows AWS
# CodePipeline to authenticate the request came from GitHub.
# Would probably be better to pull this from the environment
# or something like SSM Parameter Store.

locals {
  webhook_secret = "super-secret"
}

resource "aws_codepipeline_webhook" "github_hook" {
  name            = var.github_hook_name
  authentication  = "GITHUB_HMAC"
  target_action   = "Source"
  target_pipeline = aws_codepipeline.codepipeline.name

  authentication_configuration {
    secret_token = "${local.webhook_secret}"
  }

  filter {
    json_path    = "$.ref"
    match_equals = "refs/heads/{Branch}" #see this later
  }
}

# # See this in detail later
# # Wire the CodePipeline webhook into a GitHub repository.
resource "github_repository_webhook" "web_hook_github" {
  repository = var.repo_name
  configuration {
    url          = aws_codepipeline_webhook.github_hook.url
    content_type = "json"
    insecure_ssl = true
    secret       = local.webhook_secret
  }
  events = ["push"]
}

Logs:
aws_iam_role.example: Creating...
aws_iam_role.codepipeline_role: Creating...
aws_iam_role.codepipeline_role: Creation complete after 3s [id=test-role]
aws_iam_role_policy.codepipeline_policy: Creating...
aws_iam_role.example: Creation complete after 3s [id=example]
aws_iam_role_policy.example: Creating...
aws_codebuild_project.code_build_stage_pipeline: Creating...
aws_iam_role_policy.example: Creation complete after 4s [id=example:terraform-20200414180138343300000001]
aws_iam_role_policy.codepipeline_policy: Creation complete after 4s [id=test-role:codepipeline_policy]
aws_codebuild_project.code_build_stage_pipeline: Creation complete after 9s [id=arn:aws:codebuild:us-east-1:359761372359:project/umartahir-terraform-codebuild]
aws_codepipeline.codepipeline: Creating...
aws_codepipeline.codepipeline: Creation complete after 7s [id=umar-tahir-terraform-codepipeline]
aws_codepipeline_webhook.github_hook: Creating...
aws_codepipeline_webhook.github_hook: Creation complete after 4s [id=arn:aws:codepipeline:us-east-1:359761372359:webhook:webhook-github-codepipeline]
github_repository_webhook.web_hook_github: Creating...

Error: This resource requires GitHub organization to be set on the provider.
  on codepipeline.tf line 87, in resource "github_repository_webhook" "web_hook_github":
  87: resource "github_repository_webhook" "web_hook_github"

Answer: seems to be an existing issue.
Here is a link to the thread - https://github.com/terraform-providers/terraform-provider-github/issues/45


Touchpad for desktop

Question: Anyone got experience using a touchpad for a desktop?
Does it relieve stress on the arm?
Answer: TLDR: Yes a touchpad will have an effect on your stress if only because you use your muscles differently

Define stress? You mean as in Repetitive strain injury (RSI)?
Well RSI is an overuse injury, but in this cause overuse doesn't mean you shouldn't use your arm. You overuse it in the wrong way for (too) long stretches of time, which is straining for the muscles that control your wrist and hand.
The advantage of a touchpad would be that you have to move your hand more than with a regular mouse to get the job done, which means you don't overuse it the wrong way.
Furthermore, what's bad about most typical mouse usage is that you have to keep your wrist in a slightly dorsiflexed (in this case upwards) position all the time, due to the shape and volume of the mouse.
With a touchpad you could leave your hand lying flat or hold it in whatever position you like, which aids to the less intense use of your overused muscles.
Still, like with most injuries there are other factors that might have an influence such as stress (peer pressure and the like) or lack of coffee breaks (or whatever breaks you like to take), which won't be alleviated by the touchpad. And if you use the keyboard just as frequently as your mouse, using a bad keyboard could still give you some strain.
Disclaimer: using the touchpad the wrong way, i.e. with very tensed finger positions, might actually give you more problems in the long run, so learn to listen to your body!
Comment: Woehoe finally my Human Movement Science study comes in handy :D
Comment: A touchpad causes other kinds of stress: psychological ;)
Comment: Maybe try a trackball.
Answer: I find there are two kinds of "stress."  1) Doing the same thing over and over.  2) Doing something your bio-mechanics aren't meant to do.  A touchpad can help with both, but can also hurt with both.  Regarding 1, just switching back and forth between devices means less repetition.  You may find touchpads are more ambidextrous.  And you can certainly switch fingers at any time.  Regarding 2, start with a relaxed and comfortable hand and arm (and shoulder and body) position, then see what movements are easy to do, and try to operate the device that way and see what works for you.  (Caveat:  This is written as a fellow user, not as any kind of doctor.)

Touchpad for desktop


Where can I find site statistics, now that we have graduated?

Question: Now that we have graduated, where can I find statistics such as number of questions per day, and the answer to question ratio?
Comment: Yeah, come and hangout in chat, and reminisce about the good old days when we were considered a trusted part of the community. ;) I lost pretty much all access when, but on the upside, I've recently been allowed to approve wiki-edits again. Yey!
Answer: Now that the site has been graduated we're not really supposed to be concerned with these metrics, the idea being that the site has proven it's "healthy enough" to stand on its own (and frankly these stats are only part of the picture pre-graduation). Site analytics are available to users with 25,000 reputation or more.
For users with less reputation Stack Exchange Data Explorer queries can give some of the same information, albeit in a less-friendly format.


Minecraft Pi Permissions

Question: The Pi version of Minecraft comes as an executable. I downloaded Minecraft on a Mac, copied it to a micro-SD, then copied it to the Pi. Every time I try to run the executable it says "permission denied". Even when I use sudo it says that. When I use chmod +x it says nothing, but it won't run. How do I fix this?
Comment: What OS are you running?  Why didn't you just download Minecraft for the Pi directly on your Pi?  Perhaps you don't have an executable compiled for ARM?
Comment: @RPiAwesomeness I didn't find the "About" section, but the command worked, so apparently the OS was Raspbian (I didn't know because it was a public Pi from a group of computer enthusiasts, not mine)
Comment: What Raspberry Pi OS are you running (Raspbian, Pidora, Arch for ARMv6)? If you are on Raspbian try running `sudo chmod +rwx -R ~/mcpi && sudo chown pi -R ~/mcpi`. You can run this from anywhere, and, if you have a different user than the default pi one, swap out your username for USER in `+rwx USER` and `chown USER`. This will give your user full read, write, and execute permissions AND make sure you own the files.
Comment: @HeatfanJohn I was unable to connect to wifi, so I had no way to download it.
Comment: @Arc676 Glad you resolved your issue! I've created a full answer below, if you could mark it as such, it would be really great, as it helps keep up the site's stats and gets us closer to graduation to being a full Stack Exchange site. Also, if you plan on being involved in this community try popping into the chat occasionally. We always love a little company and it helps grow community.
Answer: Try running the command:
 file ./minecraft-pi

Where ./minecraft-pi is the executable command that you are trying to run that returns permission denied.  This command should display something like this below which is the output I get on my Pi.
./minecraft-pi: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.26, BuildID[sha1]=0x7f5a7cece83092451a55d83790b260ab639e59e9, stripped

I vaguely recall getting permission denied errors when trying to run an exectable that was built for a different processing environment.
Answer: sudo chmod +rwx -R ~/mcpi && sudo chown pi -R ~/mcpi fixed it.
Steps:
1. Download Minecraft Pi
1a. Save it somewhere on a Pi
2. Type the above command into LXTerminal
3. Use cd to enter the folder containing the executable
4. Type ./minecraft-pi
Thanks @RPiAwesomeness
Answer: This is an answer for this question that was solved in the comments. Basically, the permissions weren't correct for the minecraft-pi executable, probably because of permissions from where the minecraft-pi executable was downloaded from.
This is how to fix it:

Download Minecraft Pi either via $ wget https://s3.amazonaws.com/assets.minecraft.net/pi/minecraft-pi-0.1.1.tar.gz
Extract the minecraft-pi tarball via tar -zxvf minecraft-pi-0.1.1.tar.gz
Run sudo chmod +rwx -R ~/mcpi && sudo chown pi -R ~/mcpi
cd into the mcpi folder via cd ~/mcpi
From within the mcpi folder run ./minecraft-pi and Minecraft Pi should start up!

Have fun!

Minecraft Pi Permissions


Meta-SE discussion about "unpinning" accepted answers

Question: We should probably weigh in on this discussion that's looking for input from the component SE sites. The proposal is to no longer "pin" the accepted answer to be the first displayed, and their looking for feedback about essentially "opting in" or out.
Comment: Just for information: [Update 2](https://meta.stackexchange.com/revisions/369568/6) on the linked Meta SE post says that the default option—that is, to keep the accepted answer pinned—will not be changed for any site across the network, unless a particular site specifically requests that the option be changed based on a discussion on their local meta.
Answer: And I'll go ahead and cast my vote that I think it's a great idea and they should make it "roll out the change to all sites by default except those that opt out."
Comment: If even Math voted for unpinning, where the merits of answer should be easiest to compare, I see no reason to keep pinning in music.
Answer: If we have the option of opting out and keeping accepted answers pinned, I am in favor of opting out. My experience with our site is that in general we're better served by keeping accepted answers pinned.
Comment: @AndyBonner That may be the most extreme instance of this I've ever seen. Wow!
Comment: You're correct about Stack Overflow; I've removed the reference. And I agree that the pinning can and does go wrong — 48 to -13 notwithstanding! (sheesh!) — but while I do find the exceptions on our site very, very annoying, I do think in general we're well served by pinning.
Comment: Or maybe I'm just biased by my "48 to -13" experience: https://ell.stackexchange.com/questions/295767/how-to-refer-to-particular-years-in-a-specific-century-in-one-expression
Comment: I take that link to mean that Stack *Overflow* has made its choice, but the meta discussion I posted mentions "triaging these requests [in] mid-to-late October." Not clear to me whether it's still open to input until then.
It's not really a big deal on our site, where most questions get few answers and the accepted one is typically also the highest-voted. There are many cases on SO though of "somebody accepted an answer hastily, but it was wrong, incomplete, or is now outdated, and the better answer with 100x the votes is buried below it."


excel files edited from all devices

Question: I wanna get your opinoun for my situation.My customer has  excel files which is edited daily by herself.My customer wanna reach and edit from  all devices like tablet pc,laptop pc or mobile phone  inside her company .(it is local network)
One solution I can find is install a excel server using the share point.in that way I am planing to reach her excel file via browser from all devices and edited.
but I am not famillier with the share point.and no idea how make an excel page available on the local network.
My question is what should be the best solition on this issue.is the using share point is only solution.?whats your opinoun on this issue.
Answer: If Internet is also available on all devices, you can go for a ready made solution of Google Drive, It will sync automatically.. But the Company IT policy could be a Constraint

excel files edited from all devices


Do modulus and absolute value operations use the same sign?

Question: Do modulus and absolute value operations use the same sign? If so, do we always assume that a modulus is intended when the number is complex? If an expression says $|a+bi|$, this means I should interpret it as $\sqrt{a^2+b^2}$ and not $\sqrt{a^2+2abi-b^2}$.
Comment: The absolute value of a real number is the same as its modulus as a complex number, so there is no confusion.  The fact that $|a| = \sqrt{a^2}$ for real numbers is, from this point of view, an accident, and is not to be taken as the definition of absolute value.
Comment: Another take is that we could define $|z| = \sqrt{z\overline{z}}$. Then for real numbers we get $|x| = \sqrt{x^2}$, as $x = \overline{x}$ for $x$ real.
Comment: They both use the same sign - the result depends on the context.

In the complex case we mean $\sqrt{a^2 + b^2}$. There is no concept of a positive or negative complex number
Answer:
Do modulus and absolute value operations use the same sign?

Yes, they do.
And this is fine- when $x \in \mathbb{R}$, the modulus of $x$ is the same as the absolute value of $x$.
Why?
I'll prove it.
Let $|x|$ be the absolute value of $x$ and let $\textrm{mod(x)}$ be the modulus of $x$.
Claim: $|x|=\rm{mod(x)}$ for $x \in \mathbb{R}$.
Proof:
$\textrm{mod(x)}=\rm{mod(x+0i)}:=\sqrt{x^2+0^2}=\sqrt{x^2}=: |x|.$
$\square$

If so, do we always assume that a modulus is intended when the number is complex?

The modulus function  is a generalisation of the absolute function, so, if in doubt, use the modulus!
The absolute value makes sense only for real numbers, whereas, the modulus is defined for all (complex) numbers, and all real numbers are complex!

If an expression says $|a+bi|$, this means I should interpret it as $\sqrt{a^2+b^2}$ and not $\sqrt{a^2+2abi-b^2}$ [?]

"By definition" would be my cop-out answer, but, geometrically, we can think of the modulus or absolute value of a complex number as its distance from the origin.
For real numbers, the modulus is the same as the absolute value, as it's just the length of the number without taking into account its sign.
For a strictly-complex number (i.e. one of the form $x+yi$ where $x,y \in \mathbb{R} \setminus \{0\}$), the absolute value function has no meaning, as a strictly-complex number like $2+i$ is not negative or positive.
If we continue our idea of the absolute value being the distance from a number to the origin, we can extend the absolute value function to complex numbers, and now call this the modulus.
As an intuitive answer, more than anything, consider plotting a general point in the complex plane.

Now, you should see from the above picture that $|z|=\sqrt{a^2+b^2}$ follows immediately from Pythagoras' Theorem, since we have a right-angled triangle.
It wouldn't make sense to have $\sqrt{a^2+2abi-b^2}$, since distances are real and this is not  real ( for all $a,b \in \mathbb{R}$).
Comment: Any reason for the downvote?


Falling book and paper

Question: I've seen an experiment where a closed book with a piece of paper lying on its cover is dropped a short distance (the piece of paper is smaller than the book; the book's cover is parallel to the Earth's surface). Both book and paper fall together and this is supposed to demonstrate that all objects (regardless of their mass) experience the same acceleration when in a state of free fall. But are there other reasons why the book and paper don't separate during their fall? Would not air pressure keep the paper pressed against the book's cover? I guess I'm thinking about the experiment where you can break a ruler under a newspaper because of air pressure.
Answer:
Would not air pressure keep the paper pressed against the book's cover?

To an extent, possibly.
This is not the main reason why it is done though; although it does relate to your newspaper-ruler example.
The reason would be to minimize the effects of air drag on the piece of paper.  Although all objects influenced the same by gravity; they react differently with the air.  A piece of paper would fall a lot slower than the book if they were both exposed to air drag.  Instead; the piece of paper avoids the drag by travelling in the streamline of the book.
Realistically, if the piece of paper were to fall slower than the book under the influence of gravity (due to lower mass) then even with the air pressure, it should still slowly separate from the book.  (the reason the ruler breaks in the newspaper experiment is because you are trying to act against the pressure very quickly).
Either way; this isn't really a great experiment to demonstrate how different masses react the same to gravitational force.  Both the book and the paper have very large areas; therefore the drag force is substantial.  To eliminate the drag force they set up the experiment in a way that pressure differences could keep the paper and the book falling with similar speeds, even if gravity was acting unevenly.
Really, this test should be done in a vacuum to eliminate this source of potential error.  It's a good sign that you can recognize this error in the experiment.  Noticing details like this is important when designing good experiments.
Comment: But if the experiment was done in a vacuum there would be no need to put the paper on top of the book. They could just be dropped simultaneously but separately.
Comment: Yeah, exactly.  They didn't have a vacuum though; and wanted to show two objects of different mass.  This experiment somewhat demonstrates that; but as you noted; there could be other explanations, so it's not a great demonstration.
Answer: The actual experiment was performed with a stone and a feather in two vacuum tubes of sane length. It was demonstrated that both the stone and the feather fall the same distance in the same time, which shows that the time if fall is independent of the masses of the body.
In the experiment you stated, there may be chances of the book and the paper separating due to air interaction and upthrust. It has to be performed in a place where air is absolutely static, otherwise there may be chances of both separating.
One may argue that atmospheric pressure keeps the book and the paper together. The argument is completely valid when you look at the experiment solely. But in the light of the actual experiment that I stated above, this argument is ignored, and it is generally taken that air pressure doesn't act on the two bodies.
Comment: But what's the relevance of whether or not the air is static to the air pressure on the piece of paper?
Comment: Sorry, I had missed the main point. Edited.
Comment: The experiment was also done by Apollo 15 astronauts on the Moon: https://www.youtube.com/watch?v=KDp1tiUsZw8

Falling book and paper


Which 40k codex would I use?

Question: Thinking about starting a full army conversion project. The issue becomes if I use another faction's models. I'm looking to make Armageddon Ork Hunters which is a guard regiment. But they fight like orks. So if I convert a guard army to fit the ork codex completely. Which codex would I use the ork? Or would I still have to use guard, because looking at the army it would be like the guard looted the orks.
Answer: If you're playing casually, you do whatever you feel like so long as your opponent is happy with it.
If you're playing competitively and want to use the Ork rules, you need to stick to the normal rules for any conversions:

No potential to confuse your opponent - e.g. you can't just stick a Taurox down on the battlefield and claim it's a Trukk, it has to be clearly distinguishable from a Taurox.
What You See Is What You Get (WYSIWG) - e.g. if you want a model to be a Big Mek with Kustom Force Field, your model has to have equipment on it which generates a force field.
Games Workshop models only - they can be any Games Workshop model, whether from Warhammer 40K, Age of Sigmar or something else, but your conversion has to be Games Workshop models (with a small amount of green stuff allowed).

Is this possible? Yes, but it's a large amount of work; for actually the reverse of what you're proposing, see Matthew Beavis's amazing "Grot Guard" army. It is perhaps worth noting that Matthew has annotated the bases of the characters with their official names (Commissar Yarrick etc) in order to meet the "no confusion" rules.
Of course, everything in the end is down to the discretion of the tournament organiser (TO) - if you're intending to bring an army like this to a competitive tournament, you would be very strongly advised to start the discussion with the TO long before you arrive; don't be "that guy" that turns up with a marginally acceptable army and makes life difficult for the TO.

Which 40k codex would I use?


Feasibility of nested voxels

Question: Out of curiosity, does anyone know how feasible it would be to have a voxel engine that allowed for voxels within other voxels? For example, you would have the usual chunks filled with voxels, but instead of stopping there each voxel could become a chunk of it's own to store more, smaller voxels. The first use case that comes to mind would be for showing damage to voxels, but there could be others, such as smoother terrain. Thoughts?
Answer: It's absolutely feasible. Go and look up octrees and KD-trees. These are just two ways of nesting voxels. These were already used in the 1990s in certain voxel applications. You could also use uniform grids and thus restrict the recursion depth to 1 or 2 levels, which may lead to better cache performance with simpler code. Good luck!
Comment: OK cool, thanks! I'm excited to try this out in the nearish future then

Feasibility of nested voxels


What is the definition of "soft label" and "hard label"?

Question: In semi-supervised learning, there are hard labels and soft labels. Could someone tell me the meaning and definition of the two things?
Comment: Where have you come across these terms? Could you provide a source for that?
Answer: According to Galstyan and Cohen (2007), a hard label is a label assigned to a member of a class where membership is binary: either the element in question is a member of the class (has the label), or it is not.
A soft label is one which has a score (probability or likelihood) attached to it. So the element is a member of the class in question with probability/likelihood score of eg 0.7; this implies that an element can be a member of multiple classes (presumably with different membership scores), which is usually not possible with hard labels.
One use of soft labels in semi-supervised learning could be that the training set consists of hard labels; a classifier is trained on that using supervised learning. The classifier is then run on unlabelled data, and adds soft labels to the elements. This enlarged data set is then used for further training, where the algorithm can treat hard and soft labels differently.
Comment: Hi, My question is what models in NLP can treat differently the soft and the hard labels in the same dataset. Can they recognize the difference and treat the "hard" as the source of truth? A link also would be  very helpfull about these models. Thank you!


Appropriate use of DL and DD?

Question: I had some site templates designed for me recently. I got the final HTML code, which validates, but the structure of the document is laid out using DL-DD pairs:

    Some text.

I'm not especially familiar with those tags as I've never used them much, but they don't seem intended for document structure. Am I right? Why would a designer do this?
Answer: A DL tag is about the same as a UL tag, it starts an unordered list.
The difference being that there basically is no bullet in a DL/DD couple.
Most of the time, though, it's used for it's real use, that is, a Definition List, and is used with DT and DD, which are Definition Term and Definition Description which would look like :

CSS

Cascading Style Sheet

which will, by default, indent the term a bit, and indent it's definition a bit more.
Answer: From WC3: http://www.w3.org/TR/html401/struct/lists.html#h-10.3
Definition lists vary only slightly from other types of lists in that list items consist of two parts: a term and a description. The term is given by the DT element and is restricted to inline content. The description is given with a DD element that contains block-level content.
So given your example, these types of structures should be used for a specific type of content and not structuring of data that does not fit within this context.
Comment: My main question is, is there any valid reason a designer would use these tags for document strucuture, or is this just WTF code?
Answer: You're right in that it shouldn't be used like that. The only reason I can think of for the designer using them is that the
 tag is indented in most browsers. If they're overriding the padding/margins on them, then your guess is as good as mine.

Appropriate use of DL and DD?


Vuze is not opening once it is closed in Ubuntu 11.04?

Question: I have installed Vuze on Ubuntu 11.04.Everything is working fine.But when I close Vuze and try to reopen it, it won't open. If I restart the system and try opening Vuze it would open normally. So can someone tell me what is the problem here and how to solve this?
Comment: I'm facing the same problem with Vuze in Ubuntu 12.04. Is there anyone who can help in this regard?
Answer: If you close it the process will keep running up & (seeding & downloading) you can kill the process
pidof Java
kill <pid number>

or you can use "system monitor"

this picture shows you that "Java" is running App name "Azureus" ("Vuze" is an app made by "Azureus")
after killing the process the you can open "Vuze" again
(Sorry I was not a member in the time that you asked this question)
or you can make a "Bash" script (just like i did)
check if the "Java" process is running close it open the "Vuze" else open the "Vuze" directly (Pid variable) then make a luncher to this script Using "gnome-desktop-item-edit" in the command type if it is a shell script "sh filename.sh" or elseif python "python filname.py"
You can help the "Azureus" by sharing this info that the app is not closing correctly (reporting the bug)
Answer: Mostly it's a bug! And it's still not fixed until this day. I have vuze on Ubuntu 13.10 and I have your problem! Anyways I have a solution for you.
Try closing it not from the x button but from the "close" button in the "file" menu up to the left then try reopening it. It should open normally and it even won't display the message at the bottom right corner that says that "vuze wasn't shut down correctly". I hope this helps
Answer: Actually this is the problem in the design of vuze.
If you close vuze it is never actually closed. It runs in background with a process name java.
To see that you open the system monitor and see the running processes then you will see the java process corresponding to the vuze.
To deal with this problem you have to change the setting of the vuze to stop running in background once closed.
Go to tools->options->interface then uncheck the close minimizes to system tray...
Answer: I got a work around... Just open a .vuze file and it shows up. Looks like its been running the entire time... I'm new to Ubuntu so I don't know the terminal commands all that well. Hope this works for you.
Comment: @ karthik Venkatesan, Please make your answer more clear. Thanks.
Comment: do you mean a ".torrent" file?
Answer: Vuze tries to minimize itself to the 'system tray' when closed. With Vuze this no longer works since Ubuntu 11.04 and persists until 14.04.
To prevent this behaviour, in Options -> Interface deselect the "Close minimizes to system tray" option to prevent Vuze to stay open in the background.


why does 'got to ' mean 'must' in the present?

Question: I was watching a video interview and met the phrase "I got to say", where got to was translated as must.Why are we not using have to here ,but get, and why is the past form used if we are talking about the present? Thanks
Answer: I got to say is a elision of I've got to say. That's the history. Native speakers understand got in this context to mean have got, and therefore must is a proper translation. The past tense is not being used here; it is present perfect. When someone says, "I have got a cold," he means that he still has one. In this case, "I got to say" is "I have got to say", which refers to a present desire.
There's a great discussion on all this here:
https://english.stackexchange.com/questions/76126/have-got-verb-form-and-tense
Comment: +1 The OP heard this in an interview. In writing rather than informal speech it would probably be "have to say", perhaps not eveb "have got to say".
Comment: @FeliniusRex Thanks a lot for your help ! :)
Comment: @EthanBolker Thanks


Tortoise Git Commit Lost

Question: I wonder if you could help me. I created a new branch on GitHub using the web interface. I checked out the master repository and switched to this branch and pulled, using tortoise git.
I made all my changes and went to commit them using tortoise git. On committing, I received the error that I had no branch selected to commit to. I switched to branch again and I committed other files. I noticed that the files I had originally committed, showed as committed via a green tick, but the commit message was missing from the log. The changes are absent from the remote repository, but still present on my hard drive.
I turned my computer off and went home, to fix the issue tomorrow, after all, the file changes were still on my hard drive. I asked a colleague for help with the issue and they performed a sync. The changes to my files on the missing commit are gone. There wasn't a warning that we would be reverting changes. Does anyone have any ideas? Many thanks.
Answer: I switched my repository to temp. Looking through the reflog, my commit appeared - not the normal log. I rebased to this commit and was able to retrieve my changes - phew.
Comment: Can you share the steps you took? Screenshots / commands issued would be very helpful!

Tortoise Git Commit Lost


Can mailbox locks be rekeyed?

Question: I have two mailboxes: My primary home has a cluster mailbox with a standard CompX lock (it was replaced ~5 years ago, in case that's relevant), and my second home has a standalone mailbox that I own. I would like them both to use the same key. I know I can purchase a CompX lock online and it will probably fit in the keyhole for the Mail Boss mailbox, but is it also possible to rekey it to match my existing key? If so, is this something I can do myself or would I have to find a professional?
Comment: Have you looked closely at both of the mechanisms? It's possible that they're similar enough that you could buy two locks that are keyed alike for less than the cost of 1 plus a rekey.
Comment: It depends on locale. Some places consider the Post Office the owner of the mailbox, and you'd need to check on changes with them.
Comment: Since I installed the mailbox myself I don't think that will be an issue. This question is mainly about practicality, not legality.
Answer: It is possible to rekey lock barrels/mechanisms to use the same key if they are similar enough. You can call a locksmith to do it.  However, the cheaper way is to remove both the locks and take them into a lock smith.
If that does not look too easy, then take both keys into a locksmith and they may be able to tell you with more certainty.

Can mailbox locks be rekeyed?


I can't find my plane I bought in my hanger (GTA V Story Mode)

Question: I have recently purchased the Besra in GTA story mode playing as Michael but it does not appear in my hanger and have ended up buying it twice now!! I would also like to ask if once your plane has been destroyed is it still accessible in your hanger?
Answer: Your plane (Besra) should be in the airfield that you own, there is a glitch that sometimes sends the plane to Sands Shores Airfield. You might even find both of your planes there. Other players have also said that sometimes it takes 10 minutes to 3 hours for your plane to "arrive" almost all players says that their planes eventually arrived (or they stumbled on it at the sandy shores one) All I can say is just be patient and it should come... eventually. If the plane that you bought crashes, it will end up in the airfield it arrived in.
Answer: If it will not show up in the hangar, just go inside it and press E (pc). Then a list of purchased aircrafts will show. Simply select and confirm .... There you go.
Comment: This is the correct answer. I checked all 3 hangers and the newly purchased plane wasn't there. You actually have to go INSIDE the hangar to trigger a prompt that lets you select the plane you want to have in hangar storage. Your purchased plane should show up there.

I can’t find my plane I bought in my hanger (GTA V Story Mode)


Cassandra Super Column Family Schema Creation

Question: I am trying to create a Super Column Family that will replicate a structure like this.
{ 'hd':
    '2008/12/12 10:03': { metric1: 'blah', metric2: 'blah'}
    '2008/12/2 9:03': { metric1: 'blah', metric2: 'blah'}
   'cpu':
    '2008/12/12 10:03': { metric1: 'blah', metric2: 'blah'}
    '2008/12/2 9:03': { metric1: 'blah', metric2: 'blah'}
}

My current try looks like this:
create column family Timestep
with column_type = 'Super'
and comparator = 'AsciiType'
and subcomparator = 'DateType'
and default_validation_class = 'DoubleType'
and key_validation_class = 'AsciiType'
and column_metadata = [
    {column_name : metric1, validation_class : DoubleType}
    {column_name : metric2, validation_class : DoubleType}
];

But if I try and run the above in the cassandra-cli:
java.lang.RuntimeException: org.apache.cassandra.db.marshal.MarshalException: unable to coerce 'open' to a  formatted date (long)

Maybe I am not understanding what a super column family is properly, but any help would be awesome.
Thanks.
Answer: It is very strongly recommended that you not use supercolumns, especially in new design. They have never been problem-free, and now they are deprecated and much more capably replaced by composite keys.
Your data could be nicely represented like this in CQL 3, for example:
CREATE TABLE Timestep (
    hardware ascii,
    when timestamp,
    metric1 double,
    metric2 double,
    PRIMARY KEY (hardware, when)
);

Or, depending on exactly what you expect to have, it may make more sense to use:
CREATE TABLE Timestep (
    hardware ascii,
    metricname ascii,
    when timestamp,
    value double,
    PRIMARY KEY (hardware, metricname, when)
) WITH COMPACT STORAGE;

See this article for more information on how these translate to storage engine wide rows in Cassandra.
Answer: May I know which API u are using?
If it is Hector, then I might help you. But i personally
recommend you not to use super column because, getting sub columnlist
from a super column is a headache. Plus there are lots of performance related issues.
Moreover super columns are getting deprecated. So better go with composite keys.


Is it possible to use mini jack to lightning adapter for input?

Question: As now new iPhones are shipping with a mini jack to lightning adapter and AFAIK lightning connector should be super-programable, is it possible to get audio input from a mini jack plugged into adapter? In other words if I take a radio, and I pug a male-male mini jack into a headphones port, can I record the audio on my iPhone?
Comment: There are a few companies that make input adaptors for iDevices; most notable is [IK Multimedia](http://www.ikmultimedia.com/products/cat-view.php?C=mobile)
Answer: No, unless you use a special adapter, the audio from the radio will be send over the audio output channel of the 2.5mm headphone jack, not the input channel. This means that your radio does not function as a microphone/aux input and you can't record the audio from the radio.
Answer: Unfortunately this is not possible.
The adapter uses a DAC (digital to analog converter) to convert the digital audio signal coming from the iPhone to an electrical signal that can be passed to the headphones.
The DAC only works in one direction. For the other direction (record into the iPhone using a microphone) you'd need an ADC (analog to digital converter.


Informational resource requests

Question: What is the difference between resource-request and resource-information? In theory, any answer to a resource-request question would include information about that resource, so why do we have two tags? If you know, please tell me, if not, I recommend we supercollide these tags and merge resource-information into resource-request because it's older.
Comment: Annoyingly I don't have the reputation to fix the typo in the title. Can someone fix it please? :-)
Answer: One option is to give resource-information some text implying that such questions ask for information about a specific resource (or  a class of resources). So, the asker names a resource.
On the other hand, resource-request is for when the OP doesn't have a resource in mind and wants help in finding one given a description of the need.
So in some sense they can be inverses of each other

find me info about resource mumble
I need a resource that matches the following info.

Or, we could just drop one of them, but the questions with resource-information become a bit problematic.
Comment: I agree that they are basically inverses, and that we need both.
Comment: I see the distinction, but why does it matter in terms of searching for questions? I think that this distinction will be forgotten and ignored if we make it.

Informational resource requests


In the Political Compass test, what does "left libertarian" mean?

Question: I took a political compass quiz and it categorized me as "left libertarian". What does this mean?
If it is a party, then I don't know anything about it, and I was wondering if anyone knew of it, and if they did, what are the major tenets of its overall party platform?
If it's not a party, then what does "Left Libertarian" mean?
Comment: Without even a link to the specific quiz, it's impossilbe to answer this question.
Comment: I'm voting to close this question as off-topic because because it is basically asking us to choose who you should vote for in an upcoming election.
Comment: You should get rid of the fluff and ask a specific question. This is a question and answer site, not a forum.
Comment: Also, do you mean Libertarian? Because there are already questions asking about it.
Comment: Please [edit] clarifications (such as your country) into your question, rather than leaving them buried in comments where no one will see them.
Comment: Left/Right don't have any real meaning. In the USA, the left is associated with the Democrat party. I am pretty sure you mean libertarian, not liberation (which is more associated with armies fighting occupying forces). Libertarians value liberty/freedom. The point of those political spectrum quizzes isn't to determine which party you would vote for, but to determine your own political leanings.
Comment: Is it possibly this chart and you got Left-Libertarian? http://cdn.playbuzz.com/cdn/e9920e89-b1dd-4c21-8bc6-8c82fcbeb99a/7cdc96e6-b643-4d67-aa74-671b213569f0_560_420.jpg
Comment: In my honest opinion, those two dimensional charts are just as meaningless as the left/right scale they're supposed to replace.
Comment: I edited the question for clarity and English. I also nominated it to be reopened. We have other terminology questions out there, and this is relevant to politics as defined in the help center insofar as "left libertarians" have some consistent views on policies or political processes.
Comment: @indigochild The 'right' answer to this question would be a link-only to I presume politicalcompasstest.com/faq#what_does_it_mean? or something very much like it.
Comment: @notstoreboughtdirt - A link-only answer is never the "right" one. It could probably just be a simple summary of that content, though.
Answer: There are numerous online politics quizzes that will put you onto a graph that looks something like this

This chart is from politicalcompass.org, and you can visit that site for more information.

This is what I assume you're talking about.
Left and "Libertarian" are on different axes on the chart.

Left is another word for "Liberal", and the "Liberal" party in the United States is the Democratic party.  Usually, the Left is in favor of changing society into something new.
Right is another word for "Conservative", and the "Conservative" party in the United States is the Republican party.  Usually, the Right is in favor of keeping society as it is, or bringing it back to what it use to be.
Libertarian means you value freedom, and reduced government control  there is a Libertarian party in the United States, but it isn't as large as the 2 major parties.
Authoritarian is the opposite of Libertarian.  Authoritarians are in favor of a lot of government control.  I don't know what the Authoritarian party in the United States is, but I wouldn't be too surprised if one existed.
Comment: In Political Compass, "left" and "right" are about economics (so "left" is socialist and "right" is capitalist), while "libertarian" and "authoritarian" are only about personal freedom, not economic freedom (high economic freedom aka free market is "right" in this chart). So "left-libertarian" in Political Compass means more or less "socialist or social-democrat on economics and permissive on most moral issues" - imagine a hippie. American libertarians are "right-libertarian" on Political Compass.
Comment: Libertarian is neither left and right. The reason is if the states is out, it doesn't matter whether the states is left or right. I think a left libertarian would tend to favor a bit of wealth redistribution. May be someone like George Hendry.


Does the Fermi level correspond to the highest occupied energy level?

Question: I know that, in the band structure of a solid, the Fermi level is the energy level at which there is a 50% probability of finding an electron (at thermodynamic equilibrium), and that it doesn't have to correspond to an actual energy level (ie it's in the band gap in an insulator).
But Atkins and Shriver's Inorganic Chemistry doesn't mention this and instead defines it as the highest occupied energy level at 0 K. (page 103, 5th edition)
I was wondering if these definitions are actually equivalent. If so, can you explain how? Given the fact that in an insulator the Fermi level is in the band gap, it seems like at best the definition in Atkins is oversimplified.
Comment: It is not a straightforward concept at all, so I am not surprised that an inorganic textbook simplifies it a bit. You might look at https://aapt.scitation.org/doi/10.1119/1.1629090 for the case of an intrinsic semiconductor.
Answer: Be aware of Fermi level versus Fermi energy, as it seems to me the book speaks about the latter.
The quotes below are from both Wikipedia links.

In band structure theory, used in solid state physics to analyze the energy levels in a solid, the Fermi level can be considered to be a hypothetical energy level of an electron, such that at thermodynamic equilibrium this energy level would have a 50% probability of being occupied at any given time.

The Fermi energy is a concept in quantum mechanics usually referring to the energy difference between the highest and lowest occupied single-particle states in a quantum system of non-interacting fermions at absolute zero temperature. In a Fermi gas, the lowest occupied state is taken to have zero kinetic energy, whereas in a metal, the lowest occupied state is typically taken to mean the bottom of the conduction band.

The Fermi energy is only defined at absolute zero, while the Fermi level is defined for any temperature.

The Fermi energy is an energy difference (usually corresponding to a kinetic energy), whereas the Fermi level is a total energy level including kinetic energy and potential energy.

The Fermi energy can only be defined for non-interacting fermions (where the potential energy or band edge is a static, well defined quantity), whereas the Fermi level remains well defined even in complex interacting systems, at thermodynamic equilibrium.

Since the Fermi level in a metal at absolute zero is the energy of the highest occupied single particle state, then the Fermi energy in a metal is the energy difference between the Fermi level and lowest unoccupied single-particle state, at zero-temperature.

A collection of non interacting fermions, often called the Fermi gas is a simplified model useful in the solid state physics. There is supposed the considered fermions do not interact, so the energies of these fermion quantum states do not depend on the distribution of  these fermion quantum states.
A typical case would be the classical hydrogen atom model, applied on multielectron atoms. As electrons in the same atom interact quite a lot, it is not a good model.
For solid states, electrons and electron vacancies are often taken as  quasi fermions following Fermi-Dirac statistics for the Fermi gas,
as they are separated enough to be considered as non interacting.
Comment: Thank you, that does help. The book calls it the Fermi level but from your answer it seem like they are in some sense mixing the two concepts. When do systems with non-interacting fermions actually arise? One would suppose that electrons in a solid are inevitably going to interact with each other.
Just to be fully clear, is there no particular link between Fermi energy and Fermi level (beyond the fact that presumably Fermi worked on both!)?
Comment: Just added the paragraph about the relation of the quantities in a metal context.
Comment: Added Fermi gas and non interacting fermions note.


What is the difference between rite and ritual?

Question: I have found the word rite or ritual used separately and have also found written together like "rite and ritual". But, what are differences between them. If they are related to religions, Give me examples of both rite and ritual from Hindu and christian or buddhist relegion.
Comment: First you should show your own work.  For example, from a dictionary.
Comment: It would be better to be understood from my question itself where i have stated about rite and ritual written together and wrtten together, we can find these words if googled, Let alone showing dictionery
Comment: It would actually be better if you read and complied with the rules of this site!  One reason for closing a question reads: "Please include the research you've done, or consider if your question suits our English Language Learners site better. Questions that can be answered using commonly-available references are off-topic."  That is why GEdgar posted his comment.
Answer: Oxford Dictionaries On-line defines rite as a religious or other solemn ceremony or act.
Ritual is defined as a religious or solemn ceremony consisting of a series of actions performed according to a prescribed order: e.g. ancient fertility rituals
Both words are clearly closely connected. However rite is used more as a headline term that refers to a particular ceremony, the detailed enactment of which constitutes a ritual.
For example one could say that baptism was a Christian rite. But if one was describing the detailed manner in which it takes place, which varies greatly by denomination, one would be describing a number of different rituals
Both terms are used extensively in a metaphorical or figurative sense. e.g. The ritual of Sunday lunch in the Johnson household is unfailingly consistent.
Answer: Not much difference. Both rite and ritual can be count nouns, referring to individual formal events.

The prescribed rite/ritual for the blessing of a public house by a subdeacon takes an hour.

However, ritual (and not rite) also has an abstract non-count sense as well,
referring to the state of having formal rites in the first place.

There is enormous symbolism in ritual, especially religious ritual.


How to make the page width for text broader in Google Docs?

Question: I need to have more space for text in my Google Docs, but under Format and Edit, I cannot find how to make the page width wider. Where are these page settings in Google Docs?
Answer: If you need a wider paper side, you can change the page orientation or paper size to e.g. A3.

The Pageless modus seems is suitable for Large Images, but still limits the text width.
If you only want to view it you can of course also choose a smaller text font and zoom out by pressing Ctrl + -
Comment: Line wraps cannot be read so easily if you have far too long lines like in A3 (meaning even in portrait mode), there is a reason why the standard for code is often just 79 characters. I just wanted to share where these page margins are since I had searched for them a couple of times to no avail. Your answer to use "pageless" is a good idea and I tested it on a large doc, it adds more scrollability and oversight and takes away the narrow-looking sides. In my case, I now use a pageless A4 size in Portrait mode with 0.2 margins.
Comment: You can make "Pageless" your default, with 0.2 margins. Then you do not need to care about it any more. Doing this now since the Q/A here, and it is the best, together with Code Blocks that allows you to get wide windows going over the border of the sheet for console output.
Answer: Just go to File --> Page Setup --> Margins (inches).
Default is 1, I changed it to 0.2, up to you.

Live, 0.2 looks like:

And 0.5 like:

Side-note: this code was formatted with the Code Blocks Add-on.


Citrus wallet signup api for PHP

Question: I want to make a interface so that user can register and login themselves at citrus using PHP technology and use that wallet in their payment. Does citrus provide any API for this?
Answer: Yes, Citrus-Pay does provide APIs for Integrating with Wallet where you can define your own interface.
Alternatively, you may also use the standard UI provided by Citrus. If you want to go forward with APIs,
1) Get a signup token using the API mentioned in this link: https://developers.citruspay.com/documentation/wallettab/identity-profile/oauth-token-api/
2) Call Find Or Create User API as next step. This API will trigger an OTP to the customer's mobile number passed in the request.(A Citrus Wallet is uniquely identified by a mobile number)
API on dev guide: https://developers.citruspay.com/documentation/wallettab/identity-profile/find-or-create-a-wallet/
3) Now this OTP has to be entered in an appropriate API.Which API to be used is told in the response of find or create wallet API called in step 2. (Password-based login is also supported).
It could be sign in with MOTP API ( for an existing citrus wallet customer) or verify mobile and sign API ( for new wallet accounts just being created)enter link description here
4)You will get a full access token (prepaid_pay) in response.Pass this in header of all other APIs which you need to call on behalf of user.
5)For Eg: To make a payment using the customers existing wallet balance , use the following API : https://developers.citruspay.com/documentation/wallettab/pay-using-citrus-wallet/make-payment/
Hope this helps

Citrus wallet signup api for PHP


What words or concepts describe how something feels like/ is experienced like for the first time?

Question: I can't explain myself better than this, but I'm looking for something that describes a first impression, the experience of doing something new for the first time, specially something meaningful. For example, how you feel when you listen for the first time to your soon-to-be favorite song, or when you see a girl that you find extremely beautiful, but with a beauty that is different from all beauty you have seen.
Comment: Newfound is frequently used to describe an experience that is not just new but special. A transcendent experience may not be new but it carries the idea of going beyond the ordinary experience of things.
Answer: nascent  TFD adj.

starting to grow or develop; being born

As in:

Los Angeles Times 2019  "He did this for many artists. It was his
  gift; a rare gift. He spotted and nurtured nascent talent and brought
  to their work a layered intelligence rooted in acute observation."

nascent describes the birth or beginning of something, like a new experience, a trend, an idea, or an action.
Etymonline

From 1620s, "in the act of being born;" 1706 in the figurative sense
  of "beginning to exist or grow, coming into being,"


border image with pure css

Question: This is the psd that i have to convert to html. I have to do it with pure css.

This image has a curvy border.I have to design this curved border with pure css not image. Is there any solution to do this?
Answer: Please use Border-image property. Please see the location.
http://www.css3.info/preview/border-image/
Answer: The only thing I can think of in terms of pure CSS, is an ugly hack like creating a div for every notch/tooth and giving it CSS3 rounder borders (which require css3pie for older versions of IE). Then you can just apply the colors you need.
I'm not sure if one could call this a solution though. A more practical approach would be to use border-image, but that has more issues with browser compatibility.
Answer: I don't know exactly what you want, but if you can use CSS3, take a look at this link:
http://w3schools.com/css3/css3_borders.asp (CSS3 Rounded Corners)
Otherwise, check out one of the options in the following link:
http://w3schools.com/css/css_border.asp (Border Style)

border image with pure css


Steric Effects in Friedel-Crafts Reactions

Question: I recently came across a Friedel-Crafts reaction happening between benzoyl chloride and mesitylene with $\ce{AlCl3}$ as a catalyst. Apparently this reaction doesn't occur due to steric effects even though the mesitylene ring is highly activated by the three methyl groups. This got me wondering whether the reaction between benzoyl chloride with two methyl groups at ortho positions and benzene with $\ce{AlCl3}$ catalyst would occur or not. Most importantly, my question is: where all do steric effects become the major factor in the reaction, and how do we identify that? Why is it so?
Comment: "Highly activated due to steric effects" This statement is a bit weird. Steric effects at the site of reactivity reduce reactivity because the reactive species have a harder time with productive collisions. The general question is a bit broad because it depends on the nature of the reaction and the scale of the steric bulk.
Comment: Ah no I meant something else, I'll edit it at once.
Answer: Based on literature, I'd say the unsuccessful Friedel-Crafts reaction between benzoyl chloride and mesitylene is not due to steric reasoning. My argument is based on at least one report of Friedel-Crafts acylation on following polymethylated aromatic compounds (Ref.1):

The mono- and di-acylation have been taken place between 1,3-substitutions in each occasion as indicated in the abstract:

Diacylation of mesitylene, durene and isodurene by the Friedel–Crafts method, using the acylating agent in excess (as both solvent and reagent), gives derivatives which are of potential use as monomers. The bis(p-fluorobenzoyl) derivatives, for example, can function as the electrophilic components in poly(ether ether ketone)(PEEK)-type Polymerisations, and the bisnitrobenzoyl compounds are potential sources of novel diamines. Tribenzoylation [although not tris(p-fluorobenzoylation)] of mesitylene has been observed, but dibenzoylation of m-xylene is a much less efficient process than previously reported.

The reasoning for the resistance to dibenzoylation on m-xylene must be rationalized due to the deactivation of in-plane carbonyl $\pi$-electrons of benzoyl group on aromatic ring after first benzoylation (highly possible 1-benzoyl-2,4-dimethylbenzene). All other instances (2-benzoyl-1,3-dimethyl substitutions), the benzoyl carbonyl group is in out of plane with the corresponding aromatic nucleus (Ref.2), probably due to steric hindrance:
$$
\begin{array}{c|ccc}
\text{Compound} & \nu_\ce{C=O} \ (\ce{CH3C=O}) & \nu_\ce{C=O} \ (\ce{C6H5C=O}) & \text{ECA} \ (c.a.) \\
\hline
\text{Acetophenone}  & \pu{1688 cm-1} & - & -\\
\text{Benzophenone}  & - & \pu{1664 cm-1} & 42^\circ\\
\text{2,4,6-trimethylacetylbenzene}  & \pu{1703 cm-1} & - & 73^\circ\\
\text{2,4,6-trimethylbenzylbenzene}  & -& \pu{1672 cm-1}  & 90^\circ, 40^\circ\\
\text{2,4,6-trimethyl-1,3-diacetylbenzene}  & \pu{1705 cm-1} & - & -\\
\hline
\end{array}
$$
$^a$ ECA: Effective Conformational Angle (whenever two angles are given, first refer to the angle with mesitylene ring).
A comprehensive study of mono- and di-acylation of mesitylene have been done and in all cases, at least mono-acylation was achieved in $\gt 90\%$ whenever anticipated Ref:2). The abstract states:

The Friedel–Crafts acylation of mesitylene has been studied in detail. In the acetylation, propionylation or benzoylation reactions mono- or di-ketones may be formed. Mesitoylation leads only to the monoketone. A two-stage acylation procedure is described for the synthesis of acetylbenzoylmesitylene and acetylpropionylmesitylene. Reversibility has been shown to be a factor in these acylations, especially where an aliphatic acyl group is involved. The relationship between the stereochemistry of mesityl ketones and their u.v., i.r., and $\ce{^1H}$ n.m.r. spectra is discussed.

Overall, these results suggest that Friedel-Crafts acylation reaction would not effected by steric hindrence, at least created by 1,3-dimethyl substitutions. For example, 2,4,6-trimethylacetylbenzene (acetylmesitylene) was achieved in 92% yield; 2,4,6-trimethylbenzoylbenzene (benzoylmesitylene) in 83% yield; 2,4,6-trimethyl-1,3-diacetylylbenzene (diacetylmesitylene) in 95% yield; and 2,4,6-trimethyl-1,3-dibenzoylbenzene (dibenzoylmesitylene) in 89% yield (Ref.2).
It is also noteworthy that the nitration of mesitylene is not effected by steric effects as well. You can find more details on this aspect in here.

References:

Brian N. Hendy,   Kevin H. Patterson,   David M. Smith,   Susan E. Gardner, Neil J. Nicolson, "Polyalkylated aromatic monomers and polymers. Part 1.—Friedel–Crafts diacylation of polymethylbenzenes as a means of monomer synthesis," J. Mater. Chem. 1995, 5(2), 199-204 (https://doi.org/10.1039/JM9950500199).
P. H. Gore, J. A. Hoskins, "Friedel–Crafts acylations of aromatic hydrocarbons. Part VIII. Mono- and di-acylation of mesitylene," J. Chem. Soc. C 1970, (4), 517-522 (https://doi.org/10.1039/J39700000517).
Comment: So it seems that the reaction does occur at least once. So can it be said that in general Friedel-Crafts reactions aren't affected too much by steric hindrance? Will steric hindrance on the electrophile affect the reaction feasibility ( I know reaction rate will slow down)?
Comment: This conclution is based on 1,3-dimethyl substituents. If they are a larger group such as *iso*-propyl, the story would be different. I know for sury, if we use *tert*-Bu group, the substitution on *ortho*-position is nearly impossible. This is a good example the facts for  Zhe's comments (*vide supra*).


Guessing the gender of someone submitting a multiple choice questionnaire

Question: If I have 100 people fill out a multiple choice questionnaire (containing 10 questions with 5 answer choices for each question) and the respondent writes their gender on their questionnaire, what is the best way to guess the gender of a new person that submits the questionnaire but does not write their gender?
Answer: This would be a classification problem. You can use binary classifier labeling male and female. I'm assuming the question number would be the feature and the answers the observations. There are many classification algorithms however you should perform some kind of exploratory analysis before you attempt to classify to get a better understanding of the required preprocessing, feature importance, scaling etc. This would direct you towards the algorithm that you may want to use.  Try sklearn which has many prepossessing tools and some easy to use classification algorithms.
Answer:
This would be a classification problem as @IDontKnowCode has mentioned
If the questions remain the same for everybody, you can have 10(questions) * 5(answer choice) = 50 features
Fit a decision tree or any other classification problem into this data set

This should be a quick excercise. Best of luck :)
Answer: As mentioned by others, problem mentioned is most probably a classification based problem.
Also Data Pre-processing will play an important role here. For e.g. a particular feature (say Education) may have certain ordering among values (High-school, Bachelors, Masters).
You should make sure that such cases are well handled before selecting/building a Machine Learning Model.