Why do people rush Sorcerer's Shoes on Mordekaiser?

Question: I often see Mordekaisers rush Sorcerer's Shoes? Does it have something to do with his shield or do they need it just so they can survive the laning phase?
Comment: Hi @Frank, welcome to the site. As we are a Q&A site, not a discussion forum, we prefer that each question you have be asked as a separate question rather than having multiple questions in one post at once. This makes it easier for you to choose the best answer and also makes it easier for other to find. As such, I've edited out your question about how to survive the laning phase. It's also a bit unclear whether you mean playing *as* him or *against* him. We have a question about [countering Mordekaiser](http://gaming.stackexchange.com/questions/3191/how-do-you-counter-mordekaiser) and one...
Comment: about [his role in team fights](http://gaming.stackexchange.com/questions/67100/what-is-mordekaisers-role-in-team-fights). If neither of these cover what you're looking for, feel free to [ask a new question](http://gaming.stackexchange.com/questions/ask) about how to lane effectively as Mordekaiser.
Answer: Mordekaiser is typically built AP. Usually, APs build one of two boots: Ionian Boots of Lucidity or Sorceror's Shoes.
Mordekaiser is also a melee champion, and the early movement speed helps him get to his enemy faster without being kited too much.
Not to mention, his starting movement speed is only 315. Also, the boots give mPen which buffs all of his spells. Finally, especially if the enemy doesn't have boots, Mordekaiser can run up to him, blast Mace of Spades, Creeping Death, and Siphon in his face and run away without taking much damage.
hue.
Answer: Normally I don't play Mordekaiser that much, but it would be logical for him to rush for the boots.
First of all, it allows him to hit harder, hence filling his shield faster.
Second, he has 315 movement speed, and the boots allow him to easier escape ganks, since his only escape mechanism would be flash.
Finally, as a melee caster (assuming he goes mid), boots allow him to faster move to minions and receive even less harass from the other mid than normally (less poking at his shield).
Answer: I believe the logic behind purchasing these boots comes from Mordekaiser's passive, Iron Man. The passive states: "35% of the damage dealt from abilities is converted into a temporary absorption shield." Since the magic penetration from Sorcerer's Shoes allow your abilities to deal more damage and thus generate more shield. Additionally, the same principle applies to the Spell Vamp from Hextech Revolver (which is another core item on Mordekaiser); the life gained is based on the damage dealt.
In summary, having Sorcerer's Shoes allows you generate more shield and regenerate more life with Spell-Vamp from your abilities.


Blender video editor how to undo fade out

Question: I added fade out to a video strip in blender.
How can I remove this fade out.
No properties are showing for fade duration ect.
Answer: if you added the fadein/out like this:

select first strip and right click on opacity -> clear keyframes
same for second strip.

result:
Answer: If you select the strip and right click you'll have an option to Clear Fade.

If Adjust Last Operation is checked:

You can change the fade settings after applying it here:

Alternatively, you can change ex. the File Browser area to Graph Editor and edit the keyframes of the fade manually:


Do wires with DC current vibrate like wires with AC current (very tiny vibrations)?

Question: Do wires with DC current vibrate like wires with AC current (very tiny vibrations)?
Comment: Related: [Why don't power lines swing due to magnetic force between them?](https://physics.stackexchange.com/q/532601/238167)
Comment: They really don't have a reason to vibrate, right? Vibration occurs when something is pushing and pulling the wire over and over again. In case of DC currents, nothing is ever changing. There is no push-pull force at all. There is either _only_ a push or only a pull and the wires come close together or go farther away once and forever they need to stay like that.
Answer: Wires with DC current do not vibrate. In the cases of AC you have currents moving through the wires that are constantly changing direction. Because currents create magnetic fields, electrical wires will move back and forth, or vibrate due to these changing magnetic fields.
Answer: I am just adding to what Dr. jh says - but am adding as an answer so i can show the video below.  The magnetic force between two parallel conductors carrying current is,
$$\frac{F}{l} = \frac{\mu_0 I_1I_2}{2\pi r}$$
in N/m where r is the distance between the two conductors.
Below i show the two AC current waveforms as they go from being in-phase to 180° out-of-phase (both have magnitude of 10A peak) and r = 5 meters.  F/l is in μN/m so it shows up on this scale (notice it is twice the frequency of the currents).

This Lorentz force can actually cause problems with utility transmission line protective relaying.  Quoting from Cigre B5.47 Network protection performance audits: "Real fault cases show that bundled conductor contractions which occur as a result of the Lorentz forces associated with high fault currents can influence the reactance measurements of distance protection relays. The contractions cause an increase in the line reactance and this can lead to an underreach of distance protection relays during actual three phase faults."


Why not require a three-fifths majority to pass a bill in the US Senate instead of using a filibuster?

Question: From my reading on the filibuster, I get the impression that the filibuster in the US Senate today is equivalent to requiring a three-fifths majority. Why doesn't the Senate just change the rule to require a three-fifths majority to pass a bill?
Comment: The filibuster was never intended and it was just an accident of rules changes that made it need 60 votes to end a debate.
Comment: @JoeW sure, but the original standing-up hold-your-piss filibuster was amended in a way that was clearly intended to maintain the supermajority needed to pass a vote (except in specific cases, I know). So one could imagine amending it further the way OP said. In fact, during the nuclear option debate in 2021 the supermajority for legislation was openly considered, as such, by some senators to be a feature of the Senate.
Comment: @Gouvernathor What I mean by that was the filibuster was not present when the country was founded and it was only added later by rules changes. Some think that this was an unintended change as a result of trying to simplify the rules. The original intention for the senate was always to pass a bill with a simple majority and not to require 3/5ths to stop debate and let a bill come up for vote. If anything the needed change would be to actually require a filibuster like the do at the state level instead of just saying you want to.
Answer: Yes, they could, and this would probably be constitutional.
The rules of the House of Representatives include:

A bill or joint resolution, amendment, or conference report carrying a Federal income tax rate increase may not be considered as passed or agreed to unless so determined by a vote of not less than three-fifths of the Members voting, a quorum being present.

This has never been overturned in court and could presumably be extended to non-tax-related bills. So it seems that Congress can adopt rules that mandate a supermajority for legislation.
Edit: so why don't they? Probably because the modern filibuster mostly benefits people in the minority party, so the majority has little interest in making it more permanent. It only survives because some more moderate members of the party in the majority want to keep it.
Comment: Do you have any evidence that it has been challenged in court giving the courts a chance to rule on it in the first place? Unless someone has challenged it in court they will not look at it more making a ruling on it. Also should be noted that there has been attempts to make that a constitutional amendment. https://govtrackinsider.com/constitutional-amendment-would-require-three-fifths-votes-in-congress-to-raise-taxes-up-from-a6dd1a7653c4
Answer: You can't change the threshold of passing bills with house rules, that threshold is determined by the Constitution.
If you want to put a supermajority threshold on these things, you have to insert it in the form of another layer of procedure such as: "You need supermajority to bring the bill to a vote", which amounts to the same thing but does not contradict the Constitution.
It's worth noting that these mechanisms - arguably - are not real supermajority, since house rules can be changed with a simple majority any time. These hosue rules are only as strong as the norms which bind them in place. In this instance, the filibuster is strong because there is a strong institutional norm which holds it in place.
Comment: Which article of the constitution specifies that bills are passed by simple majority?
Comment: In partial answer to that question, there is a Constitutional rule that the VP has a deciding vote in cases in which the Senate is equally divided. But I think this is the only reference to majority voting.  There is an understanding that all decisions are made by a simple majority, except those which explicitly require a supermajority (overruling vetos, a conviction in impeachment trials)  But this is not made explicit in the Constitution! Perhaps the authors thought this so obvious as to not need spelling out.
Comment: @JamesK If not simple majority then what? In the absence of details, even reaching a consensus on which threshold is correct would have to be done through simple majority. The requirement is born out of necessity.
Comment: The notion of majority is understood but never actually stated.  There isn't a necessity.  The Senate could have decided (unanimously) to proceed on the basis of unanimity.  This  isn't so far fetched.  Many decisions of the European Council have required consensus. https://www.consilium.europa.eu/en/council-eu/voting-system/unanimity/ When there were 26 senators and no parties, this might even have be workable.  Alternatively it could be that there should be unanimity among the states.  So there *are* other models of a Senate that are not based on majority voting.


Why didn't Rassilon kill the Doctor during "The End of Time", while he was trying to decide who to shoot?

Question: During the episode "The End of Time, Part II", Rassilon just watched and waited for the Doctor to decide whether to kill the Master or him. But he had a metal gauntlet that he could have used to easily kill the Doctor. Why didn't he?
Comment: Rassilon spends about ten seconds powering that thing up and still doesn't fire it. By comparison, a pistol fires as soon as you pull the trigger
Answer: I've always had the impression it was simply an act of deceit (and to keep the Master in check; never the Doctor). Rassillion is just trying to buy time as he's well aware the Doctor ultimately won't shoot him (nor the Master).
Answer: Rassilon's entire plan to save the Time Lords required them to break out of the timelock. They were doing that by bringing Gallifrey through the time vortex by a 'link' they created. The 'link' relied on the Master being alive, as the drumbeat in his head was acting as a beacon.
The Doctor had the upper hand - he had a gun and could terminate the link by shooting The Master, or instead shoot Rassilon and halt his plan. We can only presume that Rassilon did not attack the Doctor using his gauntlet for fear that the Doctor might still manage to fire the gun at The Master and sever the link in his final moments. Instead, Rassilon tried to reason with the Doctor, by appealing to his morality:

RASSILON: The final act of your life is murder. But which one of us?

Rassilon apparently hoped that the Doctor would concede and shoot neither of them, because he is known to hate violence (it is out of character for the Doctor to use a gun). However, the Doctor persuades the Master to move and instead shoots the Master's machine which has the same effect of severing the link.
Answer: Because Rassilon knew (or thought) that The Doctor, at that point, had two options:

Allow the Time Lords to complete their plan and destroy the universe
Kill Rassilon, and then get killed in return

The reason that he didn't mind the second option was that he would not only kill The Doctor in the end, but it would be a victory of a whole other level (other then simply killing him): his morality.  If The Doctor could murder him, then that shows that even the one who holds the values of compassion and mercy at their utmost would fall eventually, and that mattered to him as much as victory.
If he didn't, the destruction of time would, in a sense, be his fault (as Mel would have believed) and it would have meant more then victory.
By simply killing him, none of this would be true.
Comment: "You see, it's not enough for me to *simply kill you* [...] I will discredit your house and all opposition in the Royal Court" ... wait, wrong sci-fi franchise.


Change the speed of Google Translate speech

Question: Is there any way to regulate the speed of spoken words in Google Translator? I find it a bit slow and have looked to see if there is a setting, but I have found nothing.
Comment: it takes me about half a second to translate a paragraph of 80 words. Maybe you need to 'regulate' your internet connection?
Comment: Thanx, but there is nothing wrong with my internet connection.  It is high speed. I'm talking about the spoken words. Not the time it takes to translate a phrase.
Comment: Oh. I didn't even know that's offered.
Answer: There is no setting to permanently change the playback speed. As you likely already know, they play the normal speed on the first click, the slower speed on the second click, and then alternate on subsequent clicks.
If the normal speed is too slow for you then you are unfortunately out of luck. If it's tolerable then I'm confident there is a way to create a custom web browser script that will force it to always play the normal speed. If that interests you then check out Tampermonkey for Chrome or Greasemonkey for Firefox. Note that this is just an addon to run custom scripts. You would need to make your own Google Translate script or find an existing one.
Comment: Good grief! I'm sorry I asked. If I knew how to create a script do you think I would've come here asking the question?   -End of discussion.
Comment: @Ella try shifting your perspective. Now you know you can script things to customize websites. If you spend some time learning it then you can figure out a solution instead of acting like the world owes you something. End of discussion indeed.
Answer: You can change the speed of HTML5 video/audio with
document.querySelector('video').playbackRate = < speed >;

with speed ranging from 0.5 to 2
to get the proper URL where the video is, check the developer tools > network and look for the network request with the type media (play audio first). then post the code above in the console and change the speed.
This works for me in Chrome, but I'm sure there must be an easier way.
Comment: you could put this in a script for tamper monkey or something
Answer: Create a new Userscript using TamperMonkey.
Remove all existing code from the script, then add the following:
Gv.prototype.play = function() {
    if (this.b != this.K || this.g != this.H || this.c != this.I) {
        if (this.m)
            var a = [this.b];
        else {
            a = Ev[Fv[this.g.toLowerCase()]];
            var b = []
              , c = this.X
              , d = this.b.replace(/[ \u3000\n\r\t\s]+/g, " ");
            Av(b, d, a, z(c.a, c), z(c.g, c));
            a = b
        }
        b = [];
        c = [];
        d = "";
        null != this.L && (d += "&" + this.L);
        null != this.v ? d += "&ttsspeed=" + this.v : 0 != this.c && (d += "&ttsspeed=" + this.c);
        this.o && (d += "&hint=" + this.o);
        for (var e = 0; e < a.length; e++)
            b.push(Hv(this, a[e], this.g, a.length, e, d)),
            c.push(a[e].length);
        this.a.set(b, this.b.length, c, {
            textlen: this.b.length,
            tl: this.g
        });
        this.K = this.b;
        this.H = this.g;
        this.I = this.c
    }
    this.a.start();
    this.T && (this.c = 0 == this.c ? 0 : 0)
}
;

No idea how long this solution will last. I'm sure Google will change something eventually. It works by overriding the existing play function with the flipping mechanism removed (it will always play at regular speed).
Answer: Google has a text-to-speech application with speed control that can be used at https://cloud.google.com/text-to-speech/


Highlight Due Date Column with color

Question: I am using SharePoint 2016.  There is a Submittal library that has been created and one of the users would like the "Due Date" column to highlight in yellow when a document that has been submitted is open and past due (see image).  I am new to Javascript and would like a step by step on how to do this.  I am familiar with creating web parts, I guess I just haven't found the correct code to enter.  Please help!
Comment: What you are trying to do is do-able, but a quicker path to a functional result given your lack of experience with JavaScript is to create two filtered views, one that only displays the items that are past the due date and another one that displays everything that is not past due date.  Although using client side rendering (JavaScript) would also work, but another problem arises: what happens if it breaks for some reason and you have to fix it?
Answer: Add the code below into a script editor web part in list view page.
<code><script type="text/javascript">
SP.SOD.executeFunc("clienttemplates.js", "SPClientTemplates", function() {
    SPClientTemplates.TemplateManager.RegisterTemplateOverrides({
        OnPostRender: function(ctx) {
            var today = new Date();
            // zero out the time portion so we will only compare days
            today.setHours(0,0,0,0);
            var rows = ctx.ListData.Row;
            for (var i=0;i<rows.length;i++){
                var status = rows[i]["Status"];
                var dateDue= new Date(rows[i]["Date_x0020_Due"]);
                dateDue.setHours(0,0,0,0);
                var rowId = GenerateIIDForListItem(ctx, rows[i]);
                var row = document.getElementById(rowId);
                if(dateDue<today&&status=="Open"){
                    row.style.backgroundColor = "yellow";
                }
            }
        }
    });
});
</script>
</code>

Highlight Due Date Column with color


ASP.Net Web Farm Monitoring

Question: I am looking for suggestions on doing some simple monitoring of an ASP.Net web farm as close to real-time as possible. The objectives of this question are to:

Identify the best way to monitor several Windows Server production boxes during short (minutes long) period of ridiculous load
Receive near-real-time feedback on a few key metrics about each box.  These are simple metrics available via WMI such as CPU, Memory and Disk Paging.  I am defining my time constraints as soon as possible with 120 seconds delayed being the absolute upper limit.
Monitor whether any given box is up (with "up" being defined as responding web requests in a reasonable amount of time)

Here are more details, things I've tried, etc.

I am not interested in logging.  We have logging solutions in place.
I have looked at solutions such as ELMAH which don't provide much in the way of hardware monitoring and are not visible across an entire web farm.
ASP.Net Health Monitoring is too broad, focuses too much on logging and is not acceptable for deep analysis.
We are on Amazon Web Services and we have looked into CloudWatch. It looks great but messages in the forum indicate that the metrics are often a few minutes behind, with one thread citing 2 minutes as the absolute soonest you could expect to receive the feedback.  This would be good to have for later analysis but does not help us real-time
Stuff like JetBrains profiler is good for testing but again, not helpful during real-time monitoring.
The closest out-of-box solution I've seen is Nagios which is free and appears to measure key indicators on any kind of box, including Windows.  However, it appears to require a Linux box to run itself on and a good deal of manual configuration.  I'd prefer to not spend my time mining config files and then be up a creek when it fails in production since Linux is not my main (or even secondary) environment.

Are there any out-of-box solutions that I am missing?  Obviously a windows-based solution that is easy to setup is ideal. I don't require many bells and whistles.
In the absence of an out-of-box solution, it seems easy for me to write something simple to handle what I need.  I've been thinking a simple client-server setup where the server requests a few WMI metrics from each client over http and sticks them in a database.  We could then monitor the metrics via a query or a dashboard or something.  If the client doesn't respond, it's effectively down.
Any problems with this, best practices, or other ideas?
Thanks for any help/feedback.
UPDATE: We looked into Cloudwatch a bit more and we may focus on trying it out. This forum post is the most official thing I can find.  In it, an Amazon representative says that the offical delay window for data is 4 minutes.  However, the user says that 2 minute old data is always reliable and 1 minute is sometimes reliable.  We're going to try it out and hope it is enough for our needs.
Answer: Used Quest software and it seemed to be a good monitoring solution. Here is a link.
http://www.quest.com/application-performance-monitoring-solutions/
Also performance monitoring of Windows may also help.
Comment: Thanks for the suggestion but that's probably too big and too expensive for us. I couldn't find licensing costs for that software but in my experience all Quest software is expensive and it probably won't be worth the cost to us.

ASP.Net Web Farm Monitoring


Difference between "a lot of" and "plenty of"

Question: I listened a phrase "plenty of" in a video.
I usually use "a lot of" to mean "many/much".
Is there a difference between "a lot of" and "plenty of"?
Answer: They are very similar, and in most cases they are interchangeable.  But, "plenty of" something implies enough of it.  For example

"I have a lot of pokemon, but I haven't collected them all yet."

vs

"I have plenty of oranges.  Please, eat one of them."

You could switch them around, and neither would be grammatically incorrect.  But since the goal of playing Pokemon is to collect all of them "plenty" doesn't quite feel right.  Plenty is best used when you have so many you don't want any more.  You can have so many Pokemon you can't remember all of their names, but still want to get more of them to finish the game.
"Enough" doesn't automatically imply "a lot."  One baked potato can be enough for your dinner, but since it is just one it isn't a lot of potatoes.  "Plenty" is like "a lot" with some sense of "enough" at the same time.
Comment: I would define _plenty_ as _more than enough for the required purpose_.


Is it possible to list cards horizontally?

Question: Is it possible to order Trello cards horizontally in lists from left to right like books on a shelf rather than vertically from top to bottom?
Answer: You will need an extension to achieve this.
There are a number of extensions returned by the Chrome Web Store search: "Trello Horizontal Lists"
I have no affiliation with either of the example extensions below.  You should review the different extensions that are available in the Chrome Web Store and do your due diligence prior to installing any 3rd party software.
Example 1

Trello Horizontal Lists
Turns Trello Lists Horizontal so they can be used for vertical comparisons.
This is a simple plugin that converts a Trello board from listing cards vertically to listing cards horizontally.
This has been built to enable vertical comparisons of cards across different lists vertically and introduces horizontal scroll.

Example 2

List Layouts for Trello
Allow Trello lists to be displayed vertically or in a grid.
The List Layouts for Trello extension adds a button to your Chrome toolbar allowing you to toggle the Trello board layout from horizontal to grid to vertical by clicking the icon.


Statistical analysis and prediction of variations in anatomical features

Question: I am doing a statistical analysis of variations in anatomical features, for example the shape of a pelvis bone. I found out that morphometric method can be used to quantify differences in geometry (e.g. shape and texture). My question is, what kind of method can I use to predict the shape variation of an anatomical feature based on a limited observation?
Reference:
1. Predictive Properties of Statistical Shape Models
2. Prediction of biomechanical parameters of the proximal femur using statistical appearance models and support vector regression.
Comment: What is the amount of data you have? I'm assuming you have a decent amount of data.
Answer: One possible method is SVM (Support vector Machines), it needs a decent amount of data to train the model. The classifier function constructed during the training completely decides the differences in data between the classes. Similar kind of study is here
We can do this using SAS/R/Python
Hope this helps !


How to add a new theme in Magento2.1.5?

Question: How to add a new theme? I am trying to add in localhost.
Answer: Take a look at magento docs for info http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/themes/theme-apply.html
Comment: another one help,i need to deploy my theme into magento,already placed the theme files into root files
Comment: i have seen lot of deploy comments some have i found some result and i am tried like this D:\wamp\www\Magentonew>php bin/magento setup:static-content:deploy in CMD but ended with error-'php' is not  recognized as an internal or external error
Answer: Like @Martins said: The official Magento documentation can help you.
Also, look at the default blank/luma themes. Looking at 'how Magento does it' is always very insightful on how you can achieve similar results yourself.

How to add a new theme in Magento2.1.5?


Why is Sun's atmosphere hotter than its surface?

Question: Can magnetic reconnection be the answer to why temperature of corona is so much higher than the surface of sun. Magnetic reconnection is a physical process occurring in highly conducting plasmas in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle acceleration. Can this be exactly what is happening in corona due to which a part of magnetic energy is converted to thermal energy which might be the reason why corona is so much hotter than surface of sun.
Answer: The most popular theories are Alfven wave heating and magnetic reconnection and nanoflares, but I do not believe that this question is fully resolved yet (as of 2022). The Parker Solar Probe will aim to collect more data by flying closer and closer to the Sun!
Answer: The problem is actually more likely the other way around: the temperature of the corona is pretty much the natural temperature of the Sun, reflecting its gravitational potential energy (corresponding to about  $10^7 K$). So the question should rather be: why is the temperature in the photosphere so low? There are no complicated theories needed to answer this, as cooling of a gas is always due to inelastic collisions, in this case the inelastic collisions  of high energy ions and electrons with neutral atoms, which turn the high kinetic energy of the plasma into radiation. Below the photosphere the density is too high for atoms to exist (the interior of the sun is just a plasma of bare nuclei and electrons). The photosphere is the region where the density (which decreases outwards) has become low enough for atoms to exist, which then in turn cool the plasma due to inelastic collision. This defines the 'surface' of the Sun with its low temperature (which corresponds actually almost exactly to a cooling factor (electron mass/proton mass). The hot coronal plasma is just likely due to the few plasma particles that make it through the photosphere without being slowed down by inelastic collisions.
So, as this is very much a non-LTE problem (given the huge energy range of about a factor 1000 involved), the attempt to address this with methods of thermodynamics (as is usually done), are destined to yield wrong answers and/or result in just more questions. On the other hand, with a suitably complex non-LTE computational model, it should only be a matter of properly implementing the relevant physical processes, as indicated above, with the the required fine detail such as to reproduce the main features of the solar corona, that is without need for any exotic physical processes.
For more details see my web page regarding coronal heating
Comment: @rfl I re-edited my answer such as to clarify that this a plausible theory but still a work in progress
Comment: This sounds reasonable. Can you point to published papers working this mechanism out in detail?
Comment: @rfl A conclusive proof would require a detailed non-LTE calculation of several processes involved here, which would require enormous computational resources given the high densities and temperatures involved. I am still figuring out how to achieve this best. As the mechanism is plausible though, I decided to put this in the public domain already. After all, any of the other proposed mechanism have not been conclusively proven either. Any constructive criticism is of course always welcome and may help to turn this into paper suitable for publication in a peer reviewed journal.
Comment: Thanks. All fair points. But I think it would be appropriate if you would edit your answer to make it clear what is mainstream physics and what is your own hypothesis.


Dual connections for Information Geometry

Question: In information Geometry, there is a definition of dual connection, which is: two affine connections $\nabla$ and $\nabla^*$ are called dual if they satisfied $$X(g(Y,Z))=g(\nabla_XY,Z)+g(Y,\nabla^*_XZ)$$
It seems that this definition depends on the metric $g$. My question is could we find another way to define the dual connections above, without the metric involved?
Comment: One can always find **a** way to define **something**. E.g., one can probably speak about dual connections on dual vector bundles or such. The true question is what you want out of this definition!
Comment: I think there is a typo here: the second summand in the display should be $g(Y,\nabla^*_X Z)$?
Comment: Oh,yes. I made a mistake, thank you!
Answer: If you have any manifold $M$ and a vector bundle $\mathcal{V}$ over $M$, then associated to any connection $\nabla$ on $\mathcal{V}$, there is indeed a dual connection $\nabla^*$ on the dual bundle $\mathcal{V}^*$ satisfying
$$ \partial_X[\xi(v)] = (\nabla^*_X \xi)(v) + \xi(\nabla_X v)$$
for sections $\xi$ of $\mathcal{V}^*$, $v$ of $\mathcal{V}$ and vectors $X \in TM$. This connection is unique, namely it is defined by the formula above (at least if the fiber space $V$ of $\mathcal{V}$ is reflexive, in particular if it is finite-dimensional).
There is no metric needed for this construction.
Answer: No, the dual connection depends strictly on the metric (that is, a change of the metric would lead to a change of the dual connection), and therefore any definition makes sense only when a metric is defined. For example,
$\nabla$ is self-dual ($\nabla=\nabla^*$)$\Longleftrightarrow \nabla$ is compatible with $g$
and of course the right condition is dependent on $g$.
Comment: Thanks for your answer, however, this is not what I want. Maybe because I didn't explain my question in a right way. Consider the dual connections over vector bundler and its dual space, I think they don not need the metrics. Since we talk about connections, I think the metric in the definition mentioned is also unnecessary.
Comment: But if one connection is defined in a bundle and the other one in the dual bundle, then the description above makes no sense, since $X$, $Y$ and $Z$ are fields. I still do not understand the setting completely.


Remove all classes except one

Question: Well, I know that with some jQuery actions, we can add a lot of classes to a particular div:

Let's say that with some clicks and other things, the div gets a lot of classes

So, how I can remove all the classes except one? The only idea I have come up is with this:
$('#container div.cleanstate').removeClass().addClass('cleanstate');

While removeClass() kills all the classes, the div get screwed up, but adding just after that addClass('cleanstate') it goes back to normal. The other solution is to put an ID attribute with the base CSS properties so they don't get deleted, what also improves performance, but i just want to know another solution to get rid of all except ".cleanstate"
I'm asking this because, in the real script, the div suffers various changes of classes.
Comment: Get classes, split them with `" "` (space) and decide for each one whether or not to delete it?
Answer: Instead of doing it in 2 steps, you could just reset the entire value at once with attr by overwriting all of the class values with the class you want:
jQuery('#container div.cleanstate').attr('class', 'cleanstate');

Sample: http://jsfiddle.net/jtmKK/1/
Answer: Use attr to directly set the class attribute to the specific value you want:
$('#container div.cleanstate').attr('class','cleanstate');

Answer: With plain old JavaScript, not JQuery:
document.getElementById("container").className = "cleanstate";

Answer: Sometimes you need to keep some of the classes due to CSS animation, because as soon as you remove all classes, animation may not work. Instead, you can keep some classes and remove the rest like this:
$('#container div.cleanstate').removeClass('removethis removethat').addClass('cleanstate');

Comment: I like the answer to remove some classes. I think the code could be `$('#container div.cleanstate').removeClass('removethis removethat').addClass('cleanstate');`. I tried to edit, but once again stackoverflow doesn't let you be helpful.
Answer: regarding to robs answer and for and for the sake of completeness you can also use querySelector with vanilla
document.querySelector('#container div.cleanstate').className = "cleanstate";

Answer: What if if you want to keep one or more than one classes and want classes except these. These solution would not work where you don't want to remove all classes add that perticular class again.
Using attr and removeClass() resets all classes in first instance and then attach that perticular class again. If you using some animation on classes which are being reset again, it will fail.
If you want to simply remove all classes except some class then this is for you.
My solution is for: removeAllExceptThese
Array.prototype.diff = function(a) {
            return this.filter(function(i) {return a.indexOf(i) < 0;});
        };
$.fn.removeClassesExceptThese = function(classList) {
/* pass mutliple class name in array like ["first", "second"] */
            var $elem = $(this);

            if($elem.length > 0) {
                var existingClassList = $elem.attr("class").split(' ');
                var classListToRemove = existingClassList.diff(classList);
                $elem
                    .removeClass(classListToRemove.join(" "))
                    .addClass(classList.join(" "));
            }
            return $elem;
        };

This will not reset all classes, it will remove only necessary.

I needed it in my project where I needed to remove only not matching classes.
You can use it $(".third").removeClassesExceptThese(["first", "second"]);

Remove all classes except one


Renamed Product still showing old name in Catalog and on Store

Question: Using Magento 2.2.5
After renaming a product and saving, the catalog still shows the old name. Edit the same product again and the change is there but the catalog listing doesn't seem to want to recognize it. Checking the actual store shows the old name as well.
I have run the reindexer and updated the cache repeatedly after trying different changes in hopes to make it recognize the new name.
Had this happen before and ended up deleting the product then recreating it. This one has order history we'd rather not lose so trying to find the correct way to get Magento 2 to recognize the new name.
Answer: Can you confirm that are you able to see your change at the website level of the product edit? Magento by default considers website level values.
Comment: Website is not seeing the change. There are 2 other products that got the same change (version number in the Product Name) and they went through fine. We have many other products with the same format (3 line items with the same version number) that also have no problem. It's just this one particular line item that doesn't want to update in the catalog listing nor on the website. All appropriate settings match the other products that don't have this problem.


How do I make a reCAPTCHA display properly on a Bootstrap modal on mobile?

Question: If I create a reCAPTCHA on a modal sign in box using Bootstrap and display on a small enough mobile device such as a Galaxy S4, the secondary modal for the CAPTCHA appears, but does not allow for scrolling, causing me to be unable to select all of the images and submit.
I've been dealing with all sorts of fun issues already today in regards to changing things within the iframe.
Is this a z-index fix, or is there more to it?
Answer: It's to do with the fact that as default bootstrap does not let you scroll below the modal, however the recaptcha image selector appears below the fold.  I've managed to get this working by setting the min-height property of the modal-dialog so that it takes into account the extra height required by the recaptcha.
You may want to adjust the height below depending on the size of the content within the modal:
.modal-dialog {
    min-height: 1000px;
}

Answer: I solved it with position absolute on the modal
#myModal {
    position: absolute;
}

To pop the modal back in position after a successful callback
function enable_sbmt(){
      if( grecaptcha.getResponse() ){
        $( "#myModal" ).css( "position", "fixed" );
        $(window).scrollTop(0);
      }
      else{ //console.log('false');
    }
}

function expired_callback(){
  $( "#myModal" ).css( "position", "absolute" );
}


Cluster evolution over time

Question: I have a dataset of transactional data with customer ID and I want to segment the dataset into groups using cluster analysis. I'm interested in following the evolution of each cluster over time, but since customers have very different behaviours (roughly 50% of the time a customer will change cluster the week after), I was wondering what would be a statistically sound approach. Is it a good idea to train a clustering algorithm every week and look backwards at the weekly evolution of each segment?
Comment: Which clustering technique are you using to generate the clusters?
Comment: I used k-means but my question was not just limited to that.
Comment: k-means will work because the number of clusters is fixed. One option is to run k-means every week over the data. You will have generated time series which you can then analyze. For example, you could plot the size of your largest cluster over time.
Answer: You can try

Dynamic mode decomposition.
Dynamic Time Warping. Found a nice resource on Towards data science blog.

These two have proven better approaches than PCA for time series clustering.
Happy coding
Answer: May be what you were looking for is the Rand index ?
This "is a measure of the similarity between two data clusterings", in other words, if the RI is close to 1 (after repeated clustering over a time window) then your segment are stable.
Answer: Cluster once.
Study the clusters and refine them to define classes.
Then classify points to these classes.
Comment: Thanks. Any reference to dive deeper? My concern is whether clustering once 2 years of monthly data would yield different results than clustering each month separately and then looking at the results.
Answer: Run Clustering periodically (say every month).
Use the elbow method to make a decision on the best number of clusters (be open to this aspect of the system changing over time).
Define / Label what each cluster represents - The centroids of each cluster represents the average behavior of the inmates within the cluster.

Cluster evolution over time


Speed: XML vs. NSUserDefaults

Question: I'm attempting to load and store (read AND write) a library of song information, and I don't know which method of storage would be more efficient.  Initially I stored an NSArray that I'd created to a NSUserDefault, which allows for read/write access. However, after looking into how iTunes stores its library information, I've considered reading and writing from an XML file. Which would be easier to implement and more effective speed/memory usage wise? Any help would be greatly appreciated..
Answer: NSUserDefaults is ment just for preferences, not for saving a lot of data. NSUserDefaults are being saved in a plist (xml format, obviously) so there shouldn't be any difference in reading and writing speed. I would recommend you to save the information in a plist inside your documents folder. Aswell there is CoreData (which is saved as SQLite) or SQLite. Both of it is more difficult to implement than plists or NSUserDefaults.
Answer: You should consider using a SQLite database, or even better CoreData to manage your library information.
Comment: I agree, for reading and writing some kind of database solution is best.

Speed: XML vs. NSUserDefaults


What to put in the body of an apology email?

Question: I'm a student writing a letter of apology to a dean at my school. I've written up the apology letter, now all I have left is to send it. But I'm a bit unsure of what to put in the body of the email itself. Do I repeat what I said but in a condensed manner? Saying how sorry I am again but in a different way?. If not, what should I put in the body? I would really appreciate some guidance because this is the first time I've had to write something like this.
Comment: This is probably better places on Academia SE for future reference, but why is the apology letter not the body of the email? This is generally an acceptable form. Else you can just write "Dear Dean, Please see the attached letter of apology. Kind Regards L to the V"
Comment: This question may be a better fit on [Academia StackExchange](https://academia.stackexchange.com/)
Comment: There's probably a case for actually taking the letter to the Dean's office, rather than sending it as an email...
Comment: @Bee I think that is a short but proper answer
Comment: @user180146 you're right, I don't know why I didn't!
Answer: There is no reason not to add the apology email as the body of the email, rather than just an attachment. That's generally pretty acceptable as an "apology letter" (emails being the modern letter).
If you did want to send the letter as an attachment, keep it simple:

"Dear Dean,
Please see the attached letter of apology.
Kind Regards L to the V"

In my answer, I have assumed you have been asked to submit this letter of apology. If not I think it makes even more sense to go with the first option, since the email itself will need to explain why you are writing to the Dean.
Comment: It occured to me that you might want to add what you are apologising for if you think your Dean will not immediately know. If it is obvious than there is no need to
Comment: OP: Whatever you do, be sure to use a formal salutation. Like in Bee's answer "Dear Dean Smith." Err on the side of formality. I mention this because a work colleague received an email from student to her and another doctor "Hey you two..." That was not good, and  he was not in the circumstance that he was writing a formal letter of apology to the Dean,
Comment: You're right, I've added an update
Answer: The recipe for a good apology is pretty much the same whether it's to the Dean, your Mom, or your partner. The person receiving the apology wants to know that you understand why what you did was wrong, and wants to have confidence that you won't repeat the mistake. Explain in your own words:

how you hurt the other person (in this case, how your actions harmed the school or student body, or could have caused harm)
what you intend doing differently in the future
how you plan to avoid making the same mistake again
Comment: This is useful information for the actual apology letter but I think the OP is looking to not repeat themselves in the email they're going to attach the apology letter to.
Comment: @BSMP you're right, I misunderstood the original post.


How do I visualise excited state MOs?

Question: I did an excited state calculation (TD-SCF)in Gaussian and wanted to see the MOs of the first excited state. But when I opened the checkpoint file in GaussView5 and clicked edit -> MOs, I could only see the configuration and MOs of the ground state. How do I see the excited state MOs in GaussView or other visualisers that can be downloaded for free?
Comment: Please let it open, as in my eyes there need some misunderstandings be cleared.
Comment: Hm. I am not a Gaussian user but this is almost certainly because one does not need the time-dependent density to calculate the time-dependent energy. Adding `density=current` should do it.
Comment: I have overruled the community decision of closing; if any of the close-voters are unhappy about that, please open a question on [meta.chemistry.se]. To the original poster I do however strongly recommend to add more context to the question. In any case it is a good idea to specify the versions of the programs you are using. It would also be helpful to know what route section you use. (cc @ph13)
Comment: @pentavalentcarbon That keyword doesn't work.
Answer: What you see, when you open your checkpoint file, is all you can see. I assume you use TDDFT and with this method you can't obtain other orbitals than the ones from the ground state. Why is this so?
Because in LR-TDDFT you calculate your ground state and apply a perturbation to it. (You can look up on the behind theory in good books like Introduction to Computational Chemistry from Frank Jensen.) The result from this calculation is presented from Gaussian like this:
Excited State   1:      Singlet-A      1.0662 eV 1162.87 nm  f=0.0007  <S**2>=0.000
110 ->113         0.60155  (0.72)
110 ->115        -0.23139  (0.11)
110 ->116         0.22569  (0.10)
Excited State   2:      Singlet-A      1.2549 eV  988.02 nm  f=0.0002  <S**2>=0.000
109 ->113        -0.39288  (0.31)
110 ->114         0.51726  (0.54)
Excited State   3:      Singlet-A      1.2929 eV  958.99 nm  f=0.0027  <S**2>=0.000
109 ->113         0.50172  (0.50)
110 ->114         0.29522  (0.17)
(The weights in spaces are added by me.)

These are the configurations of three excited states. The first excited state, for example, consists mainly (72%) from an excitation from MO 110 (HOMO) to MO 113 (LUMO+2). There are some contributions with weights of about 10% into the MOs 115 and 116. (On how to get the weights, have a look at an answer by me on this site here.)
You ask, how you can see the excited state in GaussView. You can't ... directly. And this question is also a little bit tricky, because what is it that you want to see? Here are some options:
You could

calculate the electron density of the excited state TD(Root=1) Density(Current) and subtract the electron density from the ground state. Then this difference shows you the "hole" where now is less density and the "hole" where there is more density.
calculate Charge Density Differences (CDD) with Multiwfn or Electronic Difference Density Maps (EDDM) with GaussSum which show you the same but a little bit easier as you do not need an additional calculation because they are based on the excitations and the CI coefficients.
calculate the transition density for the excited state TD(Root=1) Transition=1
calculate Natural Transition Orbitals with, e.g., Gaussian or Multiwfn, for very diffuse excitated states as NTOs reduces/optimizes the number of contributing excitations for each root with Density=(Transition=1) Pop=(Minimal,NTO,SaveNTO)

Just have a look on the manual for TDDFT, Density, FAQ and Pop.
Comment: That is what I said, you will not get different orbitals. If you optimize your geometry for this excited state, you'll get the orbitals you want. But still you would have to look at the "ground state" orbitals in the geometry of the optimized excited state.
Comment: my "Pop"-Link is wrong, I'll change it when I extend my answer soon
Comment: What I want to see is the MO of the excited state. In your example, in the first excited state, an electron transfers from MO 110 to MO 113, so I hope to see MO 110 and MO 113. Of course I can see the ground state version of them in GaussView, but I can't see the first excited state version of the two MOs.
Comment: Ok thanks. I'm not trying to visualise it any more. By the way, I don't think the weights you added are useful. We just look at the coefficients and they're helpful enough.

How do I visualise excited state MOs?


adding static property data when creating entities

Question: Suppose I have two entity types:  User and Country.
Country entities are never created and aren't mutable.  They're keyed by ISO alpha3 country codes, e.g. "USA".  They reside in the table COUNTRY with PK column ID.
Users have a many-to-one mapping to Country w/ cascade = none.  Users reside in the USER table with a FK column COUNTRY_ID that references COUNTRY(ID).
When creating a new User I might do something like:
User user = new User();
user.setCountry(em.find(Country.class, "USA"));
em.persist(user);

I gather that's wasteful, though, since it requires a query against COUNTRY first.  So I noticed I can also do this:
Country usa = new Country();
usa.setId("USA");
User user = new User();
user.setCountry(usa);
em.persist(user);

Since cascade = "none" this shouldn't need to query the COUNTRY table; it should just insert "USA" directly into USER as COUNTRY_ID.  Is that correct?
Now suppose there's some code that only ever creates Users with COUNTRY_ID = "USA".  In that case, it occurred to me to store a static instance of Country with ID = "USA" and use it for every new user?  For example:
public class UsaUserFactory implements Factory<User> {

    private static final Country USA = new Country();
    static { USA.setId("USA"); }

    public User newInstance() {
        User user = new User();
        user.setCountry(USA);
        return user;
    }
}

public SomeOtherClass {

    public void persistUser(EntityManager em, Factory<User> uf, ...) {
        User user = uf.newInstance();
        // set some other properties
        em.persist(user);
    }
}

Assume persistUser() is called concurrently from multiple threads and from within multiple persistence contexts.
My questions:

Will persisting User entities mutate my singleton "USA" Country instance in any way?
Is this inadvisable for some other reasons entirely?

The two classes above are just to illustrate the question; I'm not actually doing anything quite that silly.
Answer: I would be more inclined to try using a cache for the read-only data to reduce the actual database calls.  See here for help setting up a cache that might help.


MaxEnt Model Equivalance and Disjunction

Question: I want to use a maxent model for quite a simple problem but it doesn't behave as I expect. I'm clearly not understanding.
I have two sets of labels $L = \{A,B\}$ and $L' = \{A',B'\}$ and some relationship that holds between them $\Theta = \{Equals, Disjoint\}$. I have data of the form $<l,l',\theta>$ where $l \in L, l' \in L'$ and $\theta \in \Theta$. I want to know for a new pair from $L$ and $L'$ whether they belong to $Equals$ or $Disjoint$. Given only the evidence that $, $ and $$. I look at the class probability and it is the following:
A A' Equals[0.9656]  Disjoint[0.0344]
A B' Equals[0.0294]  Disjoint[0.9706]
B A' Equals[0.0294]  Disjoint[0.9706]
B B' Equals[0.0000]  Disjoint[1.0000]

According to the OpenNLP maxent model that uses generalised iterative scaling. The first three lines are as expected but the final line should just be uncertain i.e  Equals[0.5]  Disjoint[0.5] as there is no information about how B and B' relate to each other. Instead it seems to have associated B with class Disjoint from evidence $$ and attributed it to the unseen B, B' data.
What am I doing wrong? Is there another modelling technique that I should use instead?
Answer: Grouping the data points into a single context gives the desired result:
AA' Equals[0.9902]  Disjoint[0.0098]
AB' Equals[0.0098]  Disjoint[0.9902]
BA' Equals[0.0098]  Disjoint[0.9902]
BB' Equals[0.5000]  Disjoint[0.5000]

This way, evidence of class membership is not shared between events.


SharePoint framework to sync network folder

Question: Can I use the SharePoint framework to synchronise files from a network folder to a document library?  If not the framework is there a way to host some service that will monitor a network drive and pull any changes to a document library.
Any help appreciated.
Answer: Microsoft provide a few ways to synchronise files between your PC and SharePoint/OneDrive for Business.
For Microsoft 365, the OneDrive application allows you to synchronise files between a folder on your PC and a SharePoint document library or OneDrive for Business account:
https://support.microsoft.com/en-us/office/sync-sharepoint-files-and-folders-87a96948-4dd7-43e4-aca1-53f3e18bea9b
For SharePoint 2013/2016, you may need to use the older OneDrive client (groove.exe):
https://support.microsoft.com/en-us/office/sync-sharepoint-files-with-the-onedrive-sync-client-groove-exe-59b1de2b-519e-4d3a-8f45-51647cf291cd
If you cannot use the above options, you may be able to use Power Automate to achieve this requirement. Using the File System connector, you can connect to local or network machines. You will need to use the On-Premises Data Gateway to use this connector.
Comment: Thanks for the suggestion.  However it requires a PC running to connect to OneDrive and then to SharePoint.  I'm looking for a pure server side solution
Comment: The SharePoint framework (SPFx) is purely client side, so I don't think it will help with your requirement. It is not possible to deploy server side code to SharePoint Online, therefore you would need something between SharePoint and your network drive to synchronise files. If it's of any help, the OneDrive application can be installed on Windows Server.
Comment: Does PowerAutomate connect to Windows network drives?
Comment: Yes, you can use the File System connector to connect to network machines. I have updated my answer to include Power Automate. Please let the community know if this answers your question by choosing to accept the answer or alternatively letting us know if it doesn't via a comment.


Bond etf return

Question: When I open any etf pages there are a lot of yields specified. I assume those are some averages of underlying bond yields. I want to know the total return on my money ytd. This consist of 2 parts: one is the price change as I am buying shares and the coupon payments. Is there a metric that combines both? Or how can I calculate the actual return I receive if I in ested 100 on a particular bond etf? Possibly there is a primer someone can point me to? I got confused with all the metrics.
Comment: You can find a lot of details in [this answer](https://money.stackexchange.com/a/156572/109107).
Answer: Total Returns are not guaranteed in a bond ETF, unlike an individual bond that has guaranteed coupons and a guaranteed redemption value (barring default). The bonds within the ETF will pay coupons to the fund, which get distributed periodically based on the terms of the ETF (meaning they are not required to distribute ALL interest). But the value of the bonds can go down, which means that the ETF is worth less when you go to sell it.  So you may have a total return that is less than the periodically distributed return.  Or, more precisely, you might get a fixed periodic return, but if/when you go to sell the fund you might have a capital loss.  That periodic distribution can also go down if the ETF replaces bonds with ones that pay lower coupons.
There's no way to know what the total return of a bond fund going forward will be, so it's impossible to provide that as a metric.
Comment: I am not trying to estimate future return. I want to know the total return for the last say year or YTD, is there a metric the combines the 2? I can see on the chart the price change but there should be also metric how much of coupons have been paid.
Comment: Okay I see - most funds will give a "performance" chart that show the growth of 100 (or 1,000 or 10,000) over a certain time period, or show a "total return" percentage over 1, 3, and 5 years. Just like an equity fund, it will be inclusive of dividends (interest) and capital gains.

Bond etf return


Does walking with a high level trainer give a higher chance to find rare pokemons?

Question: Some sources seem to claim that you will find more rare pokemon the higher your level. If true, would walking together with a higher level trainer improve your chance of finding more rare pokemon?
Comment: Perhaps by "rare," they mean "higher CP."
Comment: @Koviko I don't actually, I mean pokemon which appear less often.
Comment: Maybe if you use an incense at a higher level, you'll get rarer Pokémon (my incense spawned a Kadabra today at level 16), but non-incensed spawns are shared so your level likely has no effect.
Answer: I don't believe it does. The Pokemon locations are shared among all users. It would be interesting if the spawns were dynamically generated based on the level of users in the area but somehow I doubt that. Anecdotally, I've seen roughly the same amount of rare Pokemon at level 5 as at level 15.
Answer: You are correct that the higher level you are the more rare Pokemon you seem to be able to find, but as for simply being near a high level trainer I don't think you'll be able to see all the same Pokemon as them.
The only source I have for this is personal experience when I was able to catch a rare Pokemon and told someone nearby who was new that day exactly where it was and they couldn't see it. (Although this could be caused by it "despawning" of sorts so I'm not 100% certain.)
Answer: Yes, however it's not only linked to what level they are, but also how many people you are walking with. I don't know the exact algorithm, but it is based off of both level and amount.


Is it possible to disable/enable indicator in ubuntu 16.04 VM?

Question: How to disable/enable indicator(status) in ubuntu using terminal.

 If possible, please let me know.
Comment: Please, be a little bit more specific : version, Unity/Gnome ? By "indicator(status)", you mean the icon on the upper right corner ? Or the messages popping out over there ?
Answer: You are running Unity. Maybe try, as suggested here, disabling the service providing the infos for the indicators (therefore, avoiding unity indicators to launch), type :
<code>   sudo mv /usr/lib/unity/unity-panel-service ~/unity-panel-service.bak
</code>
(You basicaly move the service file to a backup file in your home directory, to undo, simply remove them tho other way around).


Is it a security concern to have a user id in a cookie?

Question: I want to track a user who has previously logged in so that I can associate traffic behavior with their user record on our system. Does storing the user's id as a single value in a cookie cause security issues?
Comment: probably not... many sites would even use a userid in a GET.  I suppose it depends on whether a user's info is private or not.  If they don't have a publicly available "profile" it might be something to avoid... or at least to hash and use that hash for the tracking tables?  (It might give an attacker info that could lead to revealing private information... for instance checking for links across the web that refer to that uid on that site.)
Comment: What kinds of security issues are you talking about? There are numerous privacy issues and regulations. There are potential threats to your server and potential threats to the user. Can you narrow down what you are asking about?
Comment: I am referring to any issues that would deal with an attacker knowing an auto increment id or even being able to change the value because it's accessible in the browser.
Answer: It depends on how you validate the user id. Remember, cookies are user-supplied data, and should not be blindly trusted. If you want to save the userId on a cookie, make sure that you can detect when the user changed the cookie.
You could use JWT for that, so if the user modifies the cookie, the signature won't match and you can discard the cookie. Otherwise the user can impersonate anyone just by changing the cookie that he controls entirely.


Is it focus or depth of field?

Question: I was trying to shoot a group of people standing clumped but at different distances, quite close to me, think disorganized portrait. I have a Nikon d750,  and was not able to get everyone into focus.  If I brought the people closer to me in focus, then the background were blurred and vice versa.  I pushed the aperture all the way to f18 or so and it didn't bring the whole scene into focus.  Was I shooting from too close ....  Or this makes me wonder is this about AF-S vs AF-A instead of aperture and the camera choosing one point to focus upon instead of the area?  How would you compose a group shot like this to all be in focus?  Thanks!
Comment: Please add the photo(s) in question - we can't tell very much from a description.
Comment: It's important to remember that a lens is always focussed on only one distance. You cannot focus on multiple distances at the same time. Things at different distances can be rendered "acceptably in focus" through the "illusion" of depth of field, but still, the lens is focused only at one distance.
Comment: Also, what focal length were you using? Depth of field has an inverse relationship to focal length and aperture, while it has a proportional relationship to focus distance and f-number. And, yes, I know that aperture and f-number are the really same thing, but have their own inverse relationship in how you think about them...
Comment: When you say that you stopped down to f/18 and the scene still wasn't in focus, are you referring to what you saw through the viewfinder or are you talking about the picture after it was taken? Adjusting the aperture in setting doesn't change what you see, unless you use the DoF preview button. Please post all of your attempts, ideally with exif data in tact. Thanks!
Answer: It sounds like depth of field.  If (with an APS crop sensor, 30 mm lens, f/4), if you focus at say 6 feet you might have about 2 feet of DOF span, like from 5 feet to 7 feet (coarse approximations).  If your subject is distributed at say 6 to 8 feet, this 5-7 DOF zone does not include the far ones.  If you focus far, you miss the near ones. Which is your description.
If you focus on the near ones, or on the far ones, you have wasted half of your DOF range in empty space where there is no one. There are DOF calculators which compute these numbers.
Normal procedure would be to focus more near the middle depth of the group (or slightly in front of the middle), to put the zone more centered on your group. So yes, you do chose your point of focus too.
And of course, stopping down the f/stop, like from f/4 to f/8 or f/11, could greatly increase the span of DOF, so that the zone size is double or more.
DOF is rather vague, and is NOT a critically precise number.  If the calculator say DOF is 5 to 7 feet, then 7.02 feet is no different than 6.98 feet, both are at the limit of acceptability.  These 5 to 7 feet numbers are considered the extremes of acceptability, and the actual focused distance will of course always be the sharpest point.
Answer: If parts of the scene looked out of focus while you were composing it, it could be that the lens had not yet stopped down to the selected aperture. The D750 will have a depth of field preview function - this will make everything through the viewfinder darker, but it should show what will be in focus. Most SLRs keep the aperture wide open for composition, and only stop down for the exposure.
If parts are out of focus in the photograph, it's probably down to the focal length of the lens.
Answer:
I pushed the aperture all the way to f18 or so and it didn't bring the whole scene into focus. Was I shooting from too close

Yes. Depth of field increases as you focus farther away. Taking just a few steps back from the group would have given you far more depth of field than closing the aperture a couple of stops.
Play with a depth of field calculator to get a sense of how much difference a little distance can make. For example, a 30mm lens set to f/8 and a distance to subject of 2 feet gets 0.4 feet of depth of field. Switching all the way up to f/16 only gets you 0.81 feet of DOF. If you instead step back to a distance to subject of 4 feet, you get 3.83 feet of DOF, and at 6 feet you get 11.6 feet of DOF. Plug in your own numbers and compare changes to aperture to changes in distance and you'll quickly see that just a step or two would've fixed the problem.
Answer: Depth-of-field is that zone, before and after the point focused upon, that is rendered acceptably sharp. This zone is not split down the middle. It extends about 2/3 behind the point focused upon and 1/3 from the point of focus, back towards the camera. If your subjects are spaced at various distances, best if you shift your point of focus, forward of the middle. This takes advantage of the fact that depth-of-field extends further behind than in front.
Also, you should lookup "hyperfocal distance".  We can set the aperture and the distance focused upon so that depth-of-field carries to the far background (infinity symbol ∞ "as far and the eye can see". This is how the old Brownie camera of grandfather's time was set. If you set the camera to the "hyperfocal distance" all can be in focus from about 3 feet (1 meter) to infinity ∞.
A little study on this subject will go a long way as to improving shots with mixed subject distances.
Comment: How do you know that? The OP has not given us enough information regarding focal length or the distance of his subjects. It may well be that those closest to the camera are at less than MFD. Until the OP tells us, we don't know that.
Comment: At closer distances DoF is not 1/3 - 2/3, it is closer to 1:1, but it is also incredibly shallow. As you have noted, it is also effectively 1:∞ at or beyond the hyperfocal distance. It's only exactly 1:2 at a specific single distance for a given focal length, aperture, and magnification (enlargement/display size).
Comment: @ Michael Clark -- For this situation, DOF is approximately 1/3 towards and 2/3 away from the point of focus. The rest is minutia.
Comment: @ Michael Clark -- I don't know about you, but I surely can spread around the minutia. I do this so much I have a 6th sense (I think I have anyway).
Comment: The focus point being 1/3 into the zone is true when focused at 1/3 of hyperfocal.  This more often applies to landscapes.  But it is 50% at macro 1:1 and is 0% at infinity.  The OP's group was described as being "very close", so closer to 50% (maybe 45%) is much more likely true.
Answer: Remember that depth of field is about twice as large behind the point of focus as it is in front. So for a scene like this, where you want the largest usable depth of field, you should focus as close to the front of the scene as possible (if you use multi-point autofocus your camera might be choosing the wrong point).
If focusing in front made the people further back blurred, then my only suggestion is that the first person was ridiculously close to your lens or your focal length was too long. What lens were you using? Otherwise I don't see any reason why focusing on the closest person and using an aperture of F/18 will cause anything to be blurred (for comparison I often shoot at F/8 or F/11 and get everything in focus).
Comment: DoF is only one-third/two-thirds at one specific distance for a given focal length, aperture, and magnification (display size). At minimum focus distance it approaches 1:1. At anything past the hyperfocal distance it is effectively 1:∞. Please see: [this answer](https://photo.stackexchange.com/a/87460/15871) to [Why is the area in focus in front of the focus distance narrower than behind it?](https://photo.stackexchange.com/q/87447/15871)
Comment: @MichaelClark Huh, the book where I originally learned that had a diagram that showed that depth of field increases with subject distance but is always twice as large behind the subject as it is in front.
Comment: @Michael_Johnson - Your book was wrong.
Comment: @MichaelClark I gathered as much.
Answer: Based on the rather vague description you've given us (...a group of people standing clumped but at different distances, quite close to me...) it seems likely your subjects were too close to you to allow them all to fit within the depth of field of the focal length and aperture of your lens. For us to be certain, we need to know the camera's format (sensor size), focal length, aperture value, and subject distance. So far you've only given us f/18 for the aperture, which means that the effects of diffraction could be part of the issue as well.
You can only focus the lens at a single distance. Everything in front of or behind that distance will be blurry to one degree or another. The greater the distance (actually the greater the ratio of the two distances being compared), the greater the blur will be.
If more than one AF point is active and showing as in focus, that only means that each of them is indicating proper focus of a portion of the scene that is the same distance from the camera as the other portions of the scene that are being indicated as in focus.
For the same focal length and aperture, the closer the focus distance is, the more shallow the depth of field will be. Get close enough and use a wide enough aperture and you can't even get both eyes of a single person sitting at a 45 degree angle to the camera in focus at the same time!
What we call Depth of Field is the distance in front of or behind the point of focus that still appears acceptably sharp to our eyes when we view an image. DoF is dependent upon two main things: magnification and aperture. The focal length of the lens, the focus distance, and the size and distance of the image when we view the image affect magnification. You can take the same captured image and view it from a specific distance at a small size, say 8x10, and a much larger size, say 32x40, and things that look sharp in the smaller size will appear blurry in the larger one.
In the end, DoF is just an illusion, albeit a very convincing one.

Is it focus or depth of field?


Is there a definitive list of style guides?

Question: Almost every publication, journal or conference series seems to have its own style guide. Is anyone keeping track of these ? IE, is there a website which keeps a list of style guides - specifically citation styles - for various publications ? The most definitive (ie all-encompassing) list would be what I'm after.
Comment: Perhaps a [good starter](https://en.wikipedia.org/wiki/List_of_style_guides).
Comment: Also go to your school library and ask the research librarian.  You'll learn more than you ever thought possible.
Comment: Why do you need the list. Why not just grab the style guide when you know where you really going to submit?
Comment: Well, my question is somewhat rhetorical - I want to know how many different formats their are and see how they differ. It's related to bibliometric studies, not necessary for submission purposes.
Comment: https://github.com/citation-style-language/styles
Answer: This Wikipedia may be a good starting point.
There are the international ISO series. And just in the US there are style guides for general writing, legal documents, academic papers, journalism, electronic publishing, business, and computer industry. It may be better to limit your scope of study.
Answer: A dedicated literature reference software may help you to keep track of the publications already accessed, as well in cross-linking them together (for example with a mind map; like docear), as well as easing insertion of the citations in your word processor / editing software.  Beside an article about it, wikipedia holds a list to compare them.
After collection of your readings, you will benefit from their style library, simply select "this publication is for Nature", and the citations will be formatted accordingly.  If you you want to use the citations again, for a different journal, reformatting is just a click away.
Personally, as working in an environment of different operating systems, I prefer zotero with a large -- and extensible -- library of styles, and "connectors" to Microsoft Word, LibreOffice Write, Apple's office, and LaTeX.
In addition, university / research libraries often offer workshops how to work with such tools.  Because of personal preferences, I recommend exploring them, side-by-side for some time prior to make a decission in favour for one or/and the other.
Answer: Many reference managers can format citation styles automatically. This is a case where LaTeX is probably not your friend. A search of CTAN reveals around 43 styles for Biblatex and my TeX Live 2016 install has 404 bst files for Bibtex. In contrast, Endnote offers more than 6000 styles and Zotero has 8341 styles. I believe Mendeley uses data from CitationStyles.org which claims to have over 8000 styles.


In vibrational spectroscopy, what affect do overtones have on the spectra?

Question: I've been in a lecture about vibrational overtones in anharmonic oscillators. How would these affect an IR spectrum?
Comment: https://chemistry.stackexchange.com/questions/71334/aromatic-overtones
Comment: After reading the Q and A linked by @Mithoron consider the intrinsic colour of water. It is a sort of blue turquoise as red light is absorbed in a long enough path. This absorption is not electronic in nature but it is due to overtones and combinations . It is a nice example with an evident effect. Without overtones liquid water would be intrinsically colorless.
Comment: Homework: What's the difference between a harmonic and anharmonic oscillator (in QM) ? (just add to your post above)
Answer: Since a spectrum, including its overtones, is essentially a property of a molecule, one cannot really say how the overtones affect a spectrum. So, I will answer this question by first describing what an overtone is, giving an example of an effect that overtones sometimes participate in, and then an example of how overtones can be useful.
Overtones are charatceristic vibrational frequencies of a molecule which take place at approximately integer multiples of the $v=0$ vibrational modes. The existence of these overtones demonstrate that molecular vibrations are anharmonic in nature. This follows from the fact that for a purely harmonic vibration, the only non-zero transitions are those for which $\Delta v=\pm 1$. That is, harmonic oscillators can only move on state at a time. Thus, the fact that we observe these overtones tell us that the vibrations are not harmonic or anharmonic.
Now, in IR and Raman spectroscopy, there is an effect called Fermi Resonance. This effect basically allows for the mixing of multiple vibrational states. If I'm not mistaken, this also only happens for anharmonic vibrations because energy needs to be allowed to be shared between the two states which is not possible if the vibrations are pure harmonic, normal modes. I bring this up because it is quite common that one observes a Fermi resonance between an overtone and a higher frequency ground state mode. To quote the Wikipedia page,

High resolution IR spectra of most ketones reveal that the "carbonyl band" is split into a doublet. The peak separation is usually only a few cm$^{−1}$. This splitting arises from the mixing of νCO and the overtone of HCH bending modes.

Thus, if you wish, one effect that overtones have on IR spectra is their ability to participate in Fermi resonance, which leaves the appearance of a peak being split.
Sometimes it can be difficult to know if a peak being observed is in fact an overtone. Generally, overtones have low intensity, but if they participate in a Fermi resonance, they gain intensity and will look like a normal ground state vibration (depending on what mode they come from).
One place I have seen something likely similar to this is in the following paper[1]. They compute the IR spectrum of a water cluster, including the bending overtone, and show that it is likely the experimental spectrum was mis-assigned. In this example, being able to compute a spectrum independent of the bending overtone is quite useful.
Experimentally, overtones can be quite useful if there is a large number of peaks around the same frequency as a particular mode you are interested in studying. For instance, it is thought that the water dimer may play a significant role in absorption of radiation in the atmosphere and thus contribute to global warming. It is very hard, however, to determine the abundance of water dimers in the atmosphere because of the large amount of water vapor which covers up its entire infrared spectrum. Thus, ref. [2] used the fourth overtone of the $\ce{O-H}$ stretch to experimentally measure water dimers in the atmosphere.
Another example of the same use of overtones is in ref. [3]. There, the authors are interested in studying a possible intramolecular hydrogen bond, but one cannot just look at the lowest energy vibrations because they are swamped by a regular $\ce{O-H}$ stretch. Thus, the authors record infrared spectra in the regime where one would expect to find the first, second, third, and fourth overtones. It is confirmed that these are the peaks observed by simply computing the spectra from first principles. Thus, one also learns which geometric configurations cause which overtone peak.
In summary, overtones are not so much something that "affect" a spectrum, but are a necessary part of the spectrum because we live in a world where molecules vibrate anharmonically. I have also given examples of when overtones are quite a useful tool.
Just to get you thinking a bit, if and when you learn about two-photon or two-dimensional spectroscopies, imagine how overtones can then be used to gain even deeper insight into the molecules of interest.

[1]: Wang, Y., & Bowman, J. M. (2013). IR spectra of the water hexamer: Theory, with inclusion of the monomer bend overtone, and experiment are in agreement. The journal of physical chemistry letters, 4(7), 1104-1108.
[2]: Pfeilsticker, K., Lotter, A., Peters, C., & Bösch, H. (2003). Atmospheric detection of water dimers via near-infrared absorption. Science, 300(5628), 2078-2080.
[3]: Howard, D. L., Jørgensen, P., & Kjaergaard, H. G. (2005). Weak Intramolecular Interactions in Ethylene Glycol Identified by Vapor Phase OH− Stretching Overtone Spectroscopy. Journal of the American Chemical Society, 127(48), 17096-17103.


Get the most average position of X objects on a path with Y available positions

Question: Its friday, and in local time the clock is 3.22pm, so my brain wont give me a solution, so i ask:
Im trying to write a function/algorithm in Actionscript 3.0 that gives me the most average positions of x number of positions along a path of y number of available positions.
Y is always larger than X of course.
The background is, I got a map, with for example 50 possible placements of objects (along a path). But i only got 32 objects to place along this path, but i want their placements to be as average/even along that path as possible. So that it for example won't be a big gap at the end. My avaiable positions are at the moment stored in an array with point values.
If you just do totalPos/wantedPos and floor it, it will be a "ugly" gap at the end, any ideas?
EDIT:
I wanted to add the function incase anyone else wants it:
<code>function place (x : uint, y : uint ) : Array
{
    var a : Array = new Array();
    var s : Number = y / x;
    var c : Number = 0;

    for (var i : Number = 0; i<x; i++) {
        c++;
        var pos : Number = Math.round(i * s);
        a.push(posArray[pos]);
    }
    return a;
}
</code>
Assumes you have an array posArray with the possible positions already...
Answer: If you do totalPos/wantedPos, you get a number that is likely not in int.
For example 32/7 = 4.57...
If you floor it and choose 4, then you do get a big gap at the end.  However, if you accumulate the 4.57 and floor that, you will narrow the gap.
Again for example 32/7 = 4.57...  So initially you choose 4.  For the next number you get 2 * 4.57... = 9.14..., so you choose 9.  Then 3 * 4.57... = 13.71 so you choose 13.  Etc ...
It would probably be better if you rounded instead of floored.
Good luck :)
Answer: If I understand correctly, I think there is a basic algorithm for this kind of thing (but its been too long since school!).  Basically, its a recursive call so you pass in the end points and it puts an object on the middle point.  You then recurse with the start-to-middle as the first end-point, and the middle-to-end as the second.  So you keep dividing the gaps by half.
As I type this, I realize this will only work if the number of objects to distribute is a square.  However, I will leave the answer in case it gives someone else a better idea.


Example of a coproduct and epi preserving functor $F$ which does not preserve finite colimits

Question: What is an example of a functor $F:T\to S$ between toposes $T$ and $S$ which preserves coproducts and epimorphisms but which does not preserve finite colimits?
Comment: Do you mean binary coproducts or all coproducts?
Comment: All coproducts, arbitrary index set.
Answer: Here is a partial answer which suggests that any example will be very strange.
It is a fact of life that most of the functors between toposes that people think about preserve finite limits. (Perhaps the main exception is functors to/from $\mathbf{Set}$, but any coproduct-preserving functor from $\mathbf{Set}$ to a locally small category must actually be a left adjoint!) I claim that any functor between countably cocomplete toposes that preserves finite limits, countable coproducts, and epimorphisms must also preserve coequalisers.
Recall that any topos $\mathcal{E}$ is a effective regular (= Barr-exact) category, so the coequaliser of a parallel pair $f, g : X \to Y$ in $\mathcal{E}$ must be the quotient of the smallest (internal) equivalence relation on $Y$ containing the image $R \rightarrowtail Y \times Y$ of the morphism $\langle f, g \rangle : X \to Y \times Y$. Let $S \rightarrowtail Y \times Y$ be the union of $R \rightarrowtail Y \times Y$ and its opposite. Clearly, $S \rightarrowtail Y \times Y$ is the smallest symmetric relation on $Y$ that contains $R \rightarrowtail Y \times Y$. It is also straightforward to define the composite of a pair of binary relations on $Y$ using pullbacks and images. Take $T \rightarrowtail Y \times Y$ to be the union $\bigcup_{n \ge 0} (S^{\circ n} \rightarrowtail Y \times Y)$, where $S^{\circ n} \rightarrowtail Y \times Y$ denotes the $n$-fold self-composite of $S$. Of course, $T \rightarrowtail Y \times Y$ is a reflexive and symmetric relation on $Y$ and is contained in any transitive relation on $Y$ that contains $S \rightarrowtail Y \times Y$. Since pullbacks preserve limits and colimits in $\mathcal{E}$, we can also show that $T \rightarrowtail Y \times Y$ itself is a transitive relation on $Y$. Thus, it must be the smallest equivalence relation containing $R \rightarrowtail Y \times Y$.
Observe that the only operations we used in the above construction were finite limits, countable coproducts, and image factorisations in $\mathcal{E}$. It can be shown that a functor between effective regular categories that preserves kernel pairs and regular epimorphisms must also preserve quotients of equivalence relations and image factorisations. Since every epimorphism in $\mathcal{E}$ is a regular epimorphism, the main claim follows.
Thus, any example of a functor between countably cocomplete toposes that preserves countable coproducts and epimorphisms but not coequalisers must fail to preserve finite limits.


How did the shield not kill Mckay in SGA S2E14?

Question: In S2E14 "Grace Under Pressure" how did Sheppard extend the shield around Mckays puddle jumper without killing him?
Comment: @polar logically the same issue would be presented for the second jumper itself, why does the shield allow the jumper inside rather than pushing it away as it does the water? If we allow for the Jumper to be magically ok, then the same would apply to the content. Have you got a timestamp for the shield expansion, so I could take a look at the scene?
Comment: Why would it kill him?
Comment: @Valorum by at a minimum squishing him between the shield and inside of the rear compartment during expansion
Answer: Shields in the Stargate universe are often able to selectively allow objects to pass through. For example, some Goa'uld shields allow slow-moving objects through and a submerged Stargate won't let water flood in, although that's not dematerialising it rather than necessarily a shield. Similarly, we see shields that extend to the ground (such as personal shields) but they never cut into the ground, suggesting they can stop at exactly the right point to not cause damage.
Since that's the established behaviour, it's reasonable that they could slowly extend an existing shield over a stationary object without cutting into it.

We don't see the shield extending, just the finished "corridor" between the two jumpers but that seems to be what happened. Sheppard and Zelenka extended their shield over the rear of McKay's jumper, pushing back the water but forming an airtight seal with the hull (and the seabed). Since the shield was passing over his jumper, McKay wasn't affected.
Comment: @minnmass Fair point. I did wonder about the exact mechanics. I just remembered the episode with the submerged gate and Carter making some comment on it. I'll tweak the phrasing, since I reckon an Ancient device being smart about dealing with water is still a useful example.
Comment: Slight nit-pick: gates keeping water from flowing through (or air, if the destination is a space gate) isn't a shield, but the gate itself simply not dematerializing the water/air. While we do see gates with shields (notably Atlantis's), they're a defensive mechanism to prevent hostiles from entering through an incoming wormhole; they don't stop air from flooding out through an outgoing wormhole to a space gate.
Comment: @minnmass Slight nit-pick on your nit-pick: since there's no bidirectional movement of air molecules through the wormhole, there's no concept of a pressure differential, so you wouldn't expect an especially massive whoosh of air anyway. Things effectively have to be "pushed" through the gate by pressure. Of course, air at the source has its own pressure, so yes you would expect some leakage without the gate being clever about it, but not because there was a spacegate on the other end.
Comment: @AsteroidsWithWings: point about the space gate not being needed. Air molecules that happen to bump into the event horizon should be flung to the other side; since nothing can come "back" through an outbound wormhole, the event horizon should be the equivalent to a hole in the hull of a shield-less space ship. That is, the event horizon should effectively have zero "back" pressure, creating a huge pressure differential. The gate itself provides this "back" pressure to prevent the cataclysm. We just don't think about it until the pressures are obviously different on either side of the wormhole.
Comment: @minnmass Yes I conceded that but what I'm saying is that this doesn't relate to the "real terms" difference in pressure between the environments on each side, so whether one end is a spacegate or a normal gate is immaterial, and the only relevant factor is how the gate mechanism itself deals with this (which it clearly must do!).
Comment: @AsteroidsWithWings: I think we agree with each other. The only mention I can think of about how the gate handles this is in Watergate (SG1 4x07), when [Carter says](http://www.stargate-sg1-solutions.com/wiki/4.07_%22Watergate%22_Transcript) "My research indicates that the Gate actually has the ability to use density of molecular structure, and the force being exerted on the event horizon, to determine whether something's actually trying to pass through."; that it's the gate itself rather than a shield.
Comment: @minnmass Yep
Answer: In S5 E5 when the Vanir pass through Atlantis's shield a gate technician confirm that Ancient ships can pass through the shields.
(Edit)
Also in S4 E1 Adrift when the city shiels shrinks to save power and oxygen it passes through a repair team, but they die a couple seconds later from suffocation and probably vacuum/hypothermia.
Answer: If I could draw a picture this would be easier but basically as the shield expands it expands around the other jumper.
The shield is a sphere around jumper 1 as it grows it encounters jumper 2 the shield actually opens to the exact dimension of jumper 2 and continues to expand pushing the water away from it when the shield reached the other side of jumper 2 it closes over it forming an area protected from the water.
Basically the shield never actually touches the other jumper or its inhabitant.
Comment: At what point are we made aware of this sort of intelligent shield capability
Comment: @polar S02E14, if not sooner.
Comment: I think we see jumpers flying through Atlantis's shield in the opening shots of SGA: when Atlantis leaves Earth in the teaser, a puddle jumper flies towards it and, presumably, through its shield (which is clearly up at the time).
Comment: This specific mechanic has never been mentioned. Though it's hard to imagine how else it'd work...
Comment: @minnmass Can confirm, the jumper flies straight through, with an accompanying effect.


Linqtosql - joined rows

Question: In Linqtosql how do I show items from multiple rows in a single field.
eg I have a 3 table setup for tagging(entity, tag, entitytag) all linked via foreign keys.
For each entity I would like to return the name in one field and then all relevant tags in 2nd field.
eg Item1, tag1; tag2; tag3
   Item2, tag4, tag5....
VB statements preferred.
Thanks
Geoff
Answer: Okay, not sure if this is the most efficient way but it works.
Dim dc As New DataContext

Dim query = From i In dc.Items _
            Let tags = (From t In dc.ItemTags _
                        Where t.ItemID = i.ID _
                        Select t.Tag.Name).ToArray _
            Select i.ItemName, Tags = String.Join(" | ", tags)

Comment: For what you're trying to do, that's the best way I can think of.
Answer: With this answer I am assuming you have your tables setup similar to the following, names are not great, just for illustration:
AnEntity: Id, Name
ATag: Id, TagName
EntityTag: EntityId (FK to AnEntity.Id), TagId (FK to ATag.Id)
You might try this:
var entityTags = from ent in theEntities
                 from enttags in ent.EntityTags
                 group enttags by enttags.AnEntity into entityGroup
                 select new { TheEntity = entityGroup.Key, TheTags =
                              from t in entityGroup
                              select t.ATag.TagName };

I have not been able to actually test this, I'll give it a shot this afternoon and edit it if need be.  What is happening here is a SelectMany.  The 'from ent in dc.AnEntities' gets all of the entity records, then the next 'from enttags in ent.EntityTags' gets all the entity tag records for each entity.  The group by does pretty much that, groups the EntityTag records by AnEntity.  Put them in an anonymous type and you are good to go.
EDITED:
  Okay, changed the code above, it works now.  Before you would get a list of the EntityTag objects, now you get the Entiy object and a list of strings (tags) for that entity.

Linqtosql - joined rows


What is the best approach to write a literature review paper?

Question: I'm completely new to writing a review paper, so how would I best write it? Do I need to read every single paper? Or just a few sections like the introduction and results and get the info from them?
How would you approach this?
Comment: I'm starting my research for my masters degree, so it will be beneficial for me in two ways: 1. I'll get to review the literature and that is extremely needed, and 2. There are no review papers I could find on this topic, so it will also be a good contribution.
Comment: @Mithun thank you for the link! That is very helpful.
Comment: What purpose does that review serve?
Comment: Look again, a topic with 90 papers and not a single review? And sorry, nobody will print a review written by a masters student. That's for post-doc.
Comment: Possible duplicate https://academia.stackexchange.com/q/43371/17776
Comment: @Karl I've been searching for 2 months, and I didn't find.
Answer: Usually review papers are written by established researchers in that field. They already got good knowledge about the topic and a library to work with. In that case you won't read all the papers in detail again, just the parts you need. You might read newer/additional papers and yes, ofc you read the whole.
Writing a review while you are not familiar with the topic is common if you start working on that topic. Often profs want new students to write a review which means they have to read the whole literature and afterwards they are familiar with the topic. In this case you should read all the papers. In the end the prof usually gives additional input in case something is missing or wrong.
If you write the review "on your own" you definitely got to read every paper very carefully, otherwise you might miss important details. I advise against doing this.
Writing reviews correctly would be very important since it helps everyone who wants to get knowledge on that field. Sadly reviews are often completly full of errors.
Comment: Thank you! What is a reasonable time frame for a review of about 90 papers? Suppose I already have them.
Comment: @MahmoudAbdel-Mon'em One month, or thee? Depending how detailed you want it, how much you already know about the topic, etc. Ask your supervisor in what timeframe he expects you to deliver the thing.
Comment: @Karl thank you. I'll discuss it with my supervisor.


Where would I ask a question about general computer systems?

Question: Where would I ask a question relating to general computer programming? Specifically, I am wondering about some exact technicalities of kernels, and if complete systems that have been programmed to use files, and then interface with higher-level graphical interfaces are kernels. This is in contrast to the standard definition of a kernel as an interface between physical hardware and software. If not, what term would I use?
Comment: I read your current question as _"Are operating systems that work with files and use a graphical user interfaces considered kernels?"_, which in my opinion is "unclear what you're asking". Can you show, for example by elaborating what you think is considered a kernel, what a kernel does, what the alternative would be and why exactly you're asking, that you understand a little bit what you're talking about so the answers can be factual?
Comment: might be worth extending your example in this question so that you get a better response.
Comment: CodeCaster, that was exactly what I intended for you to read. However, I have added a general definition, in the way I understand it, of a kernel.
Comment: No, it is not a duplicate! This is different. I am unsure, based on those definitions in the question that you marked my question as a duplicate of.
Answer: I would suggest cs.stackexchange.com , programmers.stackexchange.com or area51.stackexchange.com for that.
It depends a lot, what is exactly your question. Cs has a scientific-mathematical direction, while programmers.stackexchange.com likes more questions from the "common experience" or even software project management side.
From the workings of the operating system kernels could be maybe serverfault.com also a good choice, although you must formulate your question to make it closely related to professional system administration.
And on area51.stackexchange.com, you can help to create new SE sites where you can ask, which is closed here as offtopic.
Comment: Thank you! However, we already have enough computer-related SE sites, it seems. :)
Comment: @LiamSchumm Not enough - sites with time tends to narrow their ontopic content, people tends to feel their questions was closed unfairly. The SE goes into a direction of a network of sites with narrow topics, in which the current central role of the stackoverflow will be only fossil.