Is there a specific way to accurately fit circles inside a curved path in Adobe Illustrator?

Question:
How would I have these circles line up perfectly inside the larger circle? I can try by hand, but that gets me nowhere.
Comment: Divide your circle up using a line rotated to a specific angle - depending on how many circles you want, then fit one circle in it and rotate it by the same angle around the same rotation axis.
Answer: We do not have a generally valid practical method to place circles so that an already drawn curve becomes the common tangent for all circles and the adjacent circles touch each other just in one point. CAD programs can make such composition by performing some complex, but invisible trial and error process if you give the tangencies as constraints. Using CAD software (and CAD plugins for Illustrator) is beyond the scope of this answer.
Circle is a special case. It's in practice possible to fill a circle in the asked way, but it needs some math. The radiuses of the small (=inside) circles and the radius of the outline circle must fulfill a trigonometric equation. The math (see Note) is elementary, but there's no need to do such calculations if you let Illustrator help. The next process utilizes smart guides and snapping so that you'll get the result with Illustrator's full accuracy - no need to zoom in and eyeball to draw the parts!

Image 1: Draw a regular polygon with the polygon tool. Only click the tool to open the dialog. Let the number of the corners be = the wanted number of the fill circles. The polygon comes out automatically so that the bottom side is horizontal. Illustrator's snapping will utilize it later. In this case the wanted number of small circles is = 7. Apply Object > Path > Add anchor points to generate the midpoint anchors to every line segment for easy drawing in later steps.
Image 2:  Draw a circle which has diameter = side AB in image 1. You can draw it directly to its final place corner B if you hold Alt and Shift keys as you draw and have snap to points and smart guides ON.
Image 3: Make copies of the drawn circle and place one to each polygon corner. They snap if you drag with the white arrow the centerpoints. The small circles are now as wanted, but drawing the tangential outline circle can be tricky. It snaps easily in Illustrator if there's an even number of small circles, but I drew the tricky case: An odd number of small circles.
The case is tricky because Illustrator's own center for the 7-gon is the center of the bounding box. It's not the center of the right outline circle. Do this:

The crossing of the red lines is the right center for the outline circle. The lines are drawn between existing anchors with the line tool.

The outline circle snaps to the top anchor point of the uppermost circle if you draw it from the center by holding Alt+Shift.

If it happens that the outline circle is already drawn and cannot be changed you must draw one approximate version with the right number of small circles as described above and scale the composition so that the outline circle has the right diameter. The scaled version has  Illustrator's full accuracy.
Note: The calculation formulas without proofs:
Rout = the radius of the tangential outline circle, assumed to be known
N = the number of the inside circles, assumed to be known
R = the radius of the inside circle placement N-gon, will be calculated
S = the radius of the inside circles, will be calculated
R = Rout/(1+sin(Pi/N))
S = R(sin(Pi/N))
The sine function assumes angles are given as radians. If you want to use degrees, change Pi/N to (180 degrees)/N.
If one wants to calculate the dimensions with these formulas and then to use a drawing program to draw the composition inside a predrawn outline circle (which cannot be moved nor scaled) he must find the symmetry center of the N-gon. For odd N polygons it must be done by drawing 2 lines between a corner and the midpoint of the opposite side like shown in image 4 above. For even N polygons the bounding box center is OK.
Answer: Here's one possible method.

Use the Polar Grid tool to make a circle with 10 radial divisions, and 0 concentric divisions

Draw a circle to fit approximately. Then zoom in, in outline view, and make small adjustments. You can use numerical adjustments to adjust the size of the circle. Obviously, a little trial and error is needed here to get the lines to touch the circle at tangents. Use smart guides to help you get it to intersect.

Copy this circle and move to the opposite side of the circle, using smart guides to get it to intersect

Select both these circles, group them, and do Object > Transform > Rotate

Set the angle to 36° (because 360/10=36), hit Copy. And hit Ctrl+D 3 times


How to change user privileges from 'Y' to 'N' in MySQL Server?

Question: I want to change a privilege to my glpiuser from 'N' to 'Y'.
In MySQL server, what is the command to do this task?
Here's the image that display my users.
I'm using Ubuntu 20.04.1
Comment: Please don't post images of text; images are often hard to read (or unreadable for people with visual impairments), they can't be used by search engines, and text can't be copied from them. Edit your question and replace the link to the image with text. Regarding the question, to grant privileges, use the [GRANT](https://dev.mysql.com/doc/refman/5.7/en/grant.html) statement.
Answer: The GRANT statement enables system administrators to grant privileges and roles, which can be granted to user accounts and roles.
The REVOKE statement revokes one or more privileges from a user account.
So, something like this will most likely do what you need:
<code>REVOKE All ON <DB> FROM user@source;
</code>
Comment: `REVOKE` is more clumsy than implied here.


Detached wheel from a moving vehicle speed

Question: If a wheel is detached from a moving vehicle, would it speed be higher than the vehicle? Why?
Comment: Assuming its not a trick question of the car screeching to a halt due to the missing wheel.
Answer: If the wheel is detached while traveling on a level plane, the wheel would travel at the same speed as the vehicle. In a frictionless environment on a level plane it would continue to travel at that same speed.
If the vehicle was traveling uphill, the wheel would slow down at a lower rate than the vehicle and would move ahead of it. This is due to the fact that the wheel and the car both possess the same translational kinetic energy per mass unit, but the wheel possesses more rotational kinetic energy per mass unit and thus more total energy per mass unit. Thus, the wheel will advance in front of the vehicle in an uphill climb because it possesses more total energy per mass unit at any particular speed and it can gain more potential energy for any given change in speed than the vehicle can. Said another way: for the same gain in vertical position and the same gain in potential energy per mass unit, the wheel will have to give up less speed because it is converting more rotational energy per mass unit into potential energy for the same change in speed.
Answer: Assume the car travels at speed $v$ and the wheel has a radius $R$. Assume also that the wheel was rolling without slipping, then:
$$v=\omega R,$$
where $\omega$ is the angular speed of the wheel.
When the wheel detaches from the car and assuming no torques or forces act on it from then on, then Newton's Laws tell us the state of motion of the wheel will not change: $v$ and $\omega$ will be conserved, 'forever'.
In the real world, forces like air drag, bumps in the road and rolling resistance do cause the wheel to decelerate somewhat and eventually come to a halt.
Answer: Why should it be faster? If you instantaneously remove the axle and let the tire roll freely (without the car crashing on it), what kind of forces would act on the wheel? There is just the rolling friction of the tire against the street.
The angular velocity of the tire would be such that the tangential velocity is the same as of the car. It just has to be that case as the car would slide otherwise.
As there are no significant forces on the tire it will just keep its motion. It would roll with the car (assuming that the car would still drive) and slowly slow down due to the friction.
Answer: No, although it's tempting to think it might because it's lighter.
Before being detached, all of the vehicle (including wheels) is moving at the same velocity. At the instant the wheel is detached, the wheel is still moving at the same speed (assuming no forces acted in the detachment).
This is true because momentum is conserved
$$
\rho_{before}=\rho_{after}  \\
(m_{vehicle} + m_{wheels})v_{vehicle} = m_{vehicle}v_{vehicle} + m_{wheels}v_{wheels}
$$
Minus $m_{vehicle}v_{vehicle}$ from both sides
$$
m_{wheels}v_{vehicle} = m_{wheels}v_{wheels} \\
v_{vehicle}= v_{wheels}
$$
Therefore the speed of the wheel(s) is the same as the speed of the car.
In reality, the wheel will quickly slow down after detaching due to frictional forces.


how can I identify network traffic that is blocked?

Question: I have an app that is waiting for a reply from a website but never continues. A browser page connects to the site fine so I think traffic is being blocked by something but I get no indications. I set the firewall to so me if it blocked something. I am running a single cpu VM using windows 12 image
Comment: Windows 12? Are you from the future?
Comment: @EEAA Thought Microsoft want to stay at Windows 10 from now on forever. Such morons ...
Comment: First off, are you sure it's blocked or is that what you are trying to confirm?
Second, you say your app is waiting for a reply from a website which you can access from a web browser.  What kind of reply are you expecting?  If you could post some more details that would help.
Answer: If traffic is being blocked, its definitely within the firewall or by the ISP. Depending on the firewall, you should have logs you can look at (or enable logging) that can allow you to see what is filtered and what isn't. If it turns out that isn't it and it's not your ISP, maybe a third party DNS service you have is doing it.


What's the convergence rate when solving L1 regularized optimization via coordinate descent with tiny step?

Question: Wondering if there is an established result for the convergence rate when solving L1 regularized optimization via coordinate descent with tiny step? By "tiny step" I mean the step is always set to a very small positive constant, involving none of those step selection technique.
Comment: you posted the same question on math.sx (http://math.stackexchange.com/questions/358379/convergence-rate-when-solving-l1-regularized-optimization-via-coordinate-descent). I think this one should be closed.

You can check results by Boyd and Vandenbergh (non technical) or more technical results by Nesterov and Nemirovsky. You can also look up ISTA and FISTA methods which should give you an idea. If I remember well you can't hope for anything better than quadratic.
Comment: I've flagged your post on math.se and I'm waiting for moderators decision there. In any case, there should be only one copy of this question on SE sites.
Comment: Sorry, I didn't realize that duplicate question is not allowed. My apology. Shall I delete the same question on math.se? The best answer for this question so far seems to be still from stats.se...
Answer: Quite slow.
Convergence rate in LASSO-type estimators are always hard to get; mostly because you don't have a good a priori knowledge of the smoothness of $f$, thanks to the $\ell_1$ objective function being non-differentiable(Ref. 1, Sec. 5, Ref. 3, Sec. 3). There are some results on the convergence of the coordinate descent method for convex differentiable minimization that state that : "for a strictly convex function which is twice differentiable in its effective domain the convergence is at least linear" (Ref. 2); but you can not use that for $\ell_1$ directly. (Actually that is the caveat missing from answer you got in math.stackexchange)
Assuming you are interested in some actual application, this thread might be of interest to you: Stochastic coordinate descent for $\ell_1$ regularization; even in the case of Stochastic CD the authors present the step size is modified though.
If you are determined to use a fixed step-size you might as well try steepest descent; given you use only gradient information you might as well try to utilize it to the max. Check how a Line Search works and what Wolfe Conditions are; step-selection (in simple cases) is not that hard to include in an optimization algorithm. :)
Comment: Thanks for your detailed and patient answer. I just find I actually haven't figured out such a question: if we solve $min \quad \phi(x)$ using coordinate descent with tiny step size, do we get the $\ell$-1 regularization path for $min \quad \left(\phi(x) + \lambda||x||_1 \right)$, where $\phi(x)$ is smoothly convex function?


TRIAC heatsinking

Question: I am thinking of using a BTA04 type TRIAC in a project to switch a power hungry mains appliance, which could draw up to 12A. I can't find a forward voltage anywhere in the datasheet, or an on-state resistance. I presume, looking at the symbol, and internal construction, that it drops about 1V (silicon diode drop). In which case it would dissipate 12W at this kind of current level and require a good heatsink. Is this correct?
Comment: [The datasheet is here](http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00004892.pdf).
Answer: The first google hit for "BTA04 voltage drop" takes me here.
There, in the product specs, it states a forward voltage drop of 1.65V
Comment: The only reference to 1.65V I can find in the datasheet is Vtm. Which would be why I didn't notice it I guess - Vd or Vdrop would be what I would be expecting. Assuming Mouser are right, though...
Comment: I see the same quoted on other sites: state voltage drop VTM <1.65V (ITM = 5.5A)
Comment: Definition found on-line:  "VTM:
PEAK FORWARD ON−STATE VOLTAGE (SCR) / PEAK ON−STATE VOLTAGE (Triac): The maximum voltage drop across the main terminals at stated conditions when the devices are in the on−state(i.e., when the thyristor is in conduction). To prevent heating of the junction, the VTM is measured at a short pulse width and low duty cycle."
Answer: I'm not familiar with that part so I did a search for "BTA04 triac" and found a datasheet right away.
First, this part is obsolete, so not a good idea for new designs.  Second, it's only rated for 4A RMS continuous, so using it with a load that could draw 12A is a bad idea.
The forward drop is in the datasheet, and is listed as 1.65V.  That's about as expected since a SCR has two junctions in its conduction path.  That's roughly what you'll get from most SCRs and TRIACs.
The method of your power calculation is correct.  It will dissipate power equal to the current thru it times the voltage accross it, which would be 12W at 12A and 1V.  However, that is considerably out of spec for this part.
Comment: Hmm. I didn't notice this was a 4A only part. I'll have to choose another one. Either way, I should expect around ~1.6V drop so about 18W dissipated, which is quite a lot, but not impossible with a good heatsink.
Answer: I know it is an old subject, but I thought I could a drop my 2 cents for future reference.

Indeed the voltage drop is between 1.5V and 2V on triacs.
Before choosing the rating of your triac, you need to analyze the load of your power supply: inrush current and permanent regime. If 12A is just the inrush current, then a 4A triac is enough, as ITSM (inrush current) is around 30A. If 12A is your RMS current, then I suggest that you prepare a good heatsink (5°C/W) with a 20+ A triac like the BTA24.

NB: There is no such thing as a "forward voltage" on a triac because it is a bidirectional device; hence, the notion of forward is irrelevant. In a triac the equivalent parameter is the VTM, which stands for Voltage drop of Triac (Maximum).

TRIAC heatsinking


How to prevent a security breach from taking your online backups with it?

Question: What techniques do you recommend for securing a online backups (to a third party service like Mozy) a backup that has the advantages of online backup but cannot be tampered with just by compromising the main system? The potential advantage of tapes is that there is at least a recent version that is not reachable by the production system at the time of the attack.
Answer: The obvious answer for what I'd like to do is arrange it so that once backups are pushed to the third party service, they're read-only for the account that the main host uses to access the backup server.  Whether Mozy and relatives facilitate this, I don't know, but if they're going to blazon "SECURE" all over their home page, you'd think they'd at least be open to a conversation about it.
Answer: There are a few suggestions:
1-You don't push the the backups to the backup system, but you pull from there.
2-Once the backup is completed, a cron job being ran by another user should move the backup
to a safe location that the initial user has no access.
3-Never reuse password between server/backup.
You should be able to do this with most backup provides that give you shell/ssh access. If your backup is via ftp/pushing only, I would switch providers...
Comment: It seem pretty risky to give the backup provider automated access to all your systems.  How does the backup system authenticate?
Answer: With BackUPMAX, all information to be backed up is encrypted on the local computer before being transmitted, using a key that is stored locally. Data is stored in the BackUPMAX Data Centers in its encrypted form. Data can only be recovered by transmitting it back to the local client, which decrypts it, again using the locally-stored key (or in the event of a disaster affecting the local computer, the same key entered by hand into the BackUPMAX Software).
The most important feature of this arrangement is that while the data is stored in the BackUPMAX Data Centers, it is encrypted and not in a readable format. The BackUPMAX Servers do not have access to the key, and without the key, the data cannot be converted to a readable format. Neither do BackUPMAX employees have access to the key.
BackUPMAX stores your data fully encrypted and protected in two mirrored data centers. Only you can access your data using your own encryption key.
Answer: I suggest calculating a hash checksum for the file(s) (sha1 for instance) and then encrypting them. You can store the checksum elsewhere and use that to verify backup integrity periodically and before a restore.
The big caveat to this is that if backups aren't read-only as chaos suggests, or the backup gets deleted (flaky service provider), then you've got a serious problem. I'm not sure that there's a way around this if you're using online backups, but even with securely stored offsite tapes, there's still a chance that they will be lost or damaged.
Comment: I'd recommend something stronger than sha1... its vulnerability to collisions would seem to make it a lot less useful in detecting intentional violations.  (A sophisticated attacker could leverage collisions to alter your data in a way that produces the same sha1 hash.)
Comment: You don't need anything stronger then sha1, really, not right now. What most tools do is they md5+sha1, making very safe...


Connection Hell and Hinnom?

Question: Why are the Jewish concepts - of what often is translated as - 'Hell' and which is often seen as a place for cleansing, purification, refining and correcting the soul (purgatory), related and connected to such a horrible place where some people used to sacrifice children)? How does the latter reflect what has become the first?
Comment: could you add sources for for the ideas in the question; such as Hinnom being connected to sacrificing children?
Comment: Simple. Because hell is believed to be a fiery furnace where people die in the blazing flames, and the only place the Jews  were able to imagine to be like hell was the valley of Hinnom where people burnt thier children, thus the name גיא הינום. And if i remember correctly, later on it was used for sanitation, where they burnt all the garbage of the nearby cities.
Comment: http://www.sefaria.org/Eruvin.19a.14?lang=he&with=Commentary&lang2=he
Comment: I don't want to know why it's called Ben Hinnom, I want to know why this valley and the references to it are connected with a place of cleansing while the stories teach that it was a place of defilement and Avodah zarah
Answer: It seems you're alluding to the discussion on this answer and the comments there. The Midrash quotes in Fred's comment there explains that fathers would place their children in fires as offerings for the idol Molech, and the children's screams would reverberate from the fire (shekolo shel tinok nohem min ha'eish). Alternatively, the priests would chant incantations (nohamim) during this process. Therefore this valley was called Ben Hinnom, and it was in this valley that an entrance to Hell can be found (Eruvin 19a).

Connection Hell and Hinnom?


Cinnamon not working on Mint 17

Question: I installed Mint 17 on an older desktop and everything is OK, but the start menu is not being rendered correctly. It either does not appear at all when you click on it, or it appears empty (no icons). The whole toolbar is also not appearing, it's almost 100% transparent and the icons (or the clock for that mater) are not showing
I logged out and logged back in with XFCE and the menu works fine. I tried re-installing Cinnamon but that did not fix it.
Is there any way to fix this? Alternatively, can I install the old XFCE theme (have it look like the old Mint 10 desktop) ?
Answer: well... i guess this is because your older hardware may not have 3d-acceleration, so desktop environments like Cinnamon, Gnome or Unity won't work.
but you can install and use MATE, Xfce, LXDE, etc. without any problem.

if you want a desktop looking like your posted picture, why you don't install the MATE-edition?
Comment: here is the [release announcement](http://blog.linuxmint.com/?p=2713) with the system requirements for recent MATE-edition.

Cinnamon not working on Mint 17


How to add email signatures to the end of email message

Question: Gmail has settings to add signatures at the end of the email thread (i.e. right at the bottom of the email thread). Would it be possible to add the signature immediately after we type the subject / message.
Answer: Yes you can quite easily with signature tweaks in Gmail.

Click the cog button on the right
From the drop-down menu, click Settings
Click Labs
Search for "Signature tweaks"
Enable Signature Tweaks
Save Changes

Now when you reply to an email, the signature will be directly after the subject line.
Here is a description with some images.
Comment: The _Signature Tweaks_ lab "graduated" some time ago, so this solution no longer works. This is now part of the general settings. Please see [this answer](http://webapps.stackexchange.com/a/54591/354).
Answer: This can be found in the General section of your Gmail settings. Scroll down to "Signature:".
To have your signature appear above any quoted text, simply make sure the box labeled

Insert this signature before quoted text in replies and remove the "--" line that precedes it

is checked. If unchecked, Gmail will append your signature at the end of all text (and put the standard "--" before it so mail clients will recognize the start of the signature block).
Answer: You can easily use this while accessing this scenario.
Comment: This doesn't answer the OP's question of how to put the signature at the top of the text.


Why is the Hamiltonian of a photon = 0?

Question: I'm studying the motion of light near Schwarzschild black holes, and I was wondering why the Hamiltonian of the Schwarzschild metric $$H = - \left( 1-\frac{2M}{r}  \right)^{-1} \frac{p_{t}^2}{2}+\left( 1-\frac{2M}{r} \right) \frac{p_{r}^2}{2}+\left( \frac{p_{ \theta}^2}{2r^2}+\frac{p_{\phi}^2}{2r^2\sin^2\theta} \right)$$
is equal to zero for photons. I know that $H < 0$ is for every other particle and $H >0$ is mathematically possible but physically very unlikely since it would mean the particle is travelling faster than light. Still I don't know why the Hamiltonian (sum of potential and kinetic energies) of photons equals 0. Could anyone please help me?
Answer: The Hamiltonian is not always the sum of potential and kinetic energies. Like the Lagrangian, it is a theoretical construct that is not unique for any given physical system, and you can always construct a time-reparametrization invariant formulation of a system where the Hamiltonian vanishes. See this answer of mine for the construction and the first part of this answer of mine for the reason time-reparametrization invariant formulations where the canonical variables are scalars under time-reparametrization have vanishing Hamiltonians.
Answer: OP's Hamiltonian of the form
$$ H~=~\frac{p^2+m^2}{2}, \qquad p^2~:=~p_{\mu}g^{\mu\nu}(x) p_{\nu}~\leq~0,\tag{1} $$ is called a super-Hamiltonian in e.g. MTW, cf. e.g. this Phys.SE post. (For a massless particle like the photon $m=0$.) The super-Hamiltonian (1) is the $e=1$ gauge of the Hamiltonian
$$H~=~ \frac{e}{2}(p^2+m^2)\tag{2}$$
for a relativistic point particle, cf. e.g. this & this Phys.SE posts. Here $e$ is a Lagrange multiplier field that imposes the mass-shell condition
$$ p^2+m^2~\approx~0.\tag{3}$$
For the super-Hamiltonian (1) the mass-shell condition (3) must be imposed by hand.
The notion of energy is (as usual) tied to the notion of worldline (WL) parameter, cf. Noether's theorem. Because of WL reparametrization invariance, this energy notion is challenged, cf. e.g. this Phys.SE post.
References:

MTW; Section 21.1 p. 489.

Why is the Hamiltonian of a photon = 0?


Keyframed UV map not exporting in .dae?

Question: I've made an oversized UV texture and keyframed the mesh face position on the UV map using AnimAll in order to change the image during an animation. Rendering the animation confirms the texture change works.
However, when after exporting to .dae the texture stays the same throughout. Is there a step I've missed or is this a limitation of the file format?
Thanks a lot
Answer: Blenders Collada exporter doesn't support Key framed UV's, also not sure if any other applications support exporting them.

Keyframed UV map not exporting in .dae?


Is Tanjiro using the fire god's breath dance and Nezuko using his ability a deus ex machine? Does it have foreshadow?

Question: In chapter 19 against Rui the dance and the sanguine explosion take place, do they have a past reference? or is he a deus ex author's error? I need your help
Answer: It could be considered a Deus ex machina. To quote from its definition:

...a plot device whereby a seemingly unsolvable problem in a story is suddenly and abruptly resolved by an unexpected and unlikely occurrence.

The 'unsolvable problem' here would be the fight between Rui and Tanjiro since the latter was on the verge of losing to the former's seemingly overwhelming strength. Tanjiro then discovers a new skill using a different breathing technique and while it may not have 'abruptly resolved' the problem, it was 'unexpected and unlikely' since he was only shown to use Water breathing techniques and it was enough to buy time for reinforcements to arrive, as seen in Episode 20.
But was this an error? I don't think so. This event was meant as the beginning to unraveling of Tanjiro's past. Personally, I think it was a good way since it makes you curious about the background of Tanjiro's family, whether they were really just a family who makes charcoal or was there something more since his father seems to know breathing techniques. Was there foreshadowing before this? None. Rather, this is the foreshadowing to something later on in the storyline. All the unanswered questions from this part will eventually be answered later on as the story progresses. You can read the manga or wait for the anime to adapt everything.
Answer: There isn't a ton of foreshadowing, but I would argue it's not an error or bad storytelling. I think it was completely intentional and works well in the story.
We didn't know beforehand that Tanjiro's father passed an ability down to him, but we knew there was more to Tanjiro's father than there seemed. Muzan recognized the hanafuda earrings the first time he and Tanjiro met, which were passed down to Tanjiro from his father. So Tanjiro's father was someone a demon lord would remember, and fear enough to try and kill anyone wearing his earrings. There's also the mystery of Tanjiro's burn scar. We don't find out during the series how he got it, so it's a mystery from his past. It symbolically associates him with fire, which gets us thinking about mysteries in his past related to fire, which eventually leads to the fire dance.
The deus ex machina becomes bad storytelling when it destroys dramatic tension and conflict. I don't think that happens here. Unlocking the fire dance doesn't actually solve any of Tanjiro's problems directly. It doesn't even kill Rui, the enemy he was fighting. At best it keeps the fight going so Rui can't kidnap Nezuko and buys some time for Tomioka to show up and kill off Rui. And unlocking the fire dance sets up future stories. It's a new mystery for Tanjiro to unravel, and also a new challenge for him to figure out how to use it and how to combine it with his water breathing techniques. So I don't think the fire dance needed a ton of foreshadowing. It's not the end of a story, it's the beginning, and I imagine it's explored more deeply as the story goes on (in the manga or in a second season of the anime that maybe hopefully is coming someday).


When was the design for the "original" Enterprise (NX-01) created?

Question: While watching Star Trek: First Contact, I noticed that Captain Picard keeps a case with models of all the previous Enterprises, including what seemed to me to be the Enterprise NX-01.

This ship first appeared in the TV show Star Trek: Enterprise, which began in the early 2000s. When was the design of the ship first finalized to look the way it did? Had the design appeared in a previous episode that I was not aware of, or was this a preview to what we would se in Enterprise?
Comment: I'm assuming the ship that you thought was the the _NX-01_ was the ship on the far right? Those are the nacelles of the _Enterprise E_.
Comment: I know that I didn't see the Enterprise-E. I'll have to watch First Contact again, but I am 90% sure that I saw the NX-01. I wish there was a better image.
Comment: @DonatelloSwansino - there are better images - from the production designer himself, of the set of the film you are asking about, as well as a statement from the same that the NX is in *no way* depicted because it was 5 years from being designed in real-life. See my answer :)
Answer: None of the ships in the case resemble the NX-01 except in as much as the NX was designed to resemble the ships already depicted.
The ships displayed are the Constitution class (TOS), A, B, C, D and E
Eaves himself states as to the NX-01's apparent absence:

"it hadn't even been invented yet!!! this was at least 5 years before
  Enterprise came out. Sorry"

Source: John Eaves - Star Trek First Contact production designer

What of Star Trek Nemesis? One may be forgiven for thinking that since Star Trek: Enterprise had started production, perhaps the NX-01 was depicted as a gold model on the Enterprise-E in that film. Also - no:
Interview with John Eaves discussing Star Trek: Nemesis ships:

Moving ahead another couple of years, to Star Trek Nemesis, we are
  back to the observation lounge in what would be the Big E's final
  mission. The lounge set got a big face lift and the addition of a
  much-larger display area for the Enterprise models. Instead of six
  ships, this time there were going to be 12. For the second case, we
  built the Voyager, the Excelsior, the Grissom, the Reliant and under
  construction were the Phoenix and the Defiant. The deadline for these
  models moved when the filming scheduled changed the set order, and the
  observation lounge got moved up considerably. To make a long story
  short, the additional models didn't make it to the set and instead the
  E models were duplicated in pairs on either side of the viewing
  screen.
Comment: My personal take is that the NX-01 only became named "Enterprise" after the events in "First Contact" altered the timeline.  In the original unaltered timeline the NX-01 was named "Dauntless" as suggested by the Voyager episode "Hope and Fear".  After Picard and the Enterprise returned home, Dulmer and Luscly interviewed him and presented him with an NX-01 model to put in the display case.
Comment: NCC-1701 is the original Constitution and Constitution refit (destroyed in ST III); the model is the pre-refit. NCC-1701-A is the second Constitution Refit to bear the name given to Kirk in ST IV (and the model shown) . NCC-1701-B is the Excelsior Class seen in *Generations*. NCC-1701-C is the Ambassador Class destroyed by Romulans defending a Klingon colony in 2344. NCC-1701-D is the Galaxy Class ship commanded by Picard. NCC-1701-E is the Sovereign Class also commanded by Picard. That's six.
Comment: The Enterprise E never had an NX model @EmsleyWyatt - even in Nemesis (which might fit your theory of the NX being presented after the events of First Contact) - however, the Nemesis E has no NX model - just the same gold ships - again - from John Eaves, production designer on the films: http://www.startrek.com/article/guest-blog-the-lineage-of-ships-that-bear-the-name-enterprise
Comment: Blame it on Q...
Comment: If they depict Enterprise A, B, C, D and E, what is the 6th model?
Comment: @JohnP [Relevant drunk Scotty scene](https://www.youtube.com/watch?v=1A1TZQk5Wgk)
Answer: The Enterprise NX-01 was not affiliated with the United Federation of Planets like the other Enterprises, hence the prefix "U.S.S." (United StarShip or United SpaceShip), the NX-01 did not have a prefix, but in my opinion the NX-01 should have been U.E.S. (United Earth Ship); note: that the Fortunate Son and the Horizon had the prefix "E.C.S." (Earth Cargo Ship). That being said, when the Federation was formed, they started over at NX-01 and launched the U.S.S. Dauntless NX-01, with the "U.S.S." prefix. This should explain why when ever anyone mentions the original Enterprise, why they are referring to Kirk's Enterprise is because they are actually referring to the original Enterprise built by the Federation. Even the NX-01 was not the original Enterprise, there are plenty of Enterprises that came before that, such as the H.M.S. Enterprize or the shuttlecraft Enterprise OV-101 and of course the U.S.S. Enterprise CVN-65 which was once visited by Chekhov and Uhura in Star Trek IV: The Voyage Home.
The dedication plaque of the Enterprise-E states "Sixth Starship to bear the name".


young's modulus vs longitudal deformation modulus

Question: Young's modulus is typiccaly denoted with E. I have come accross a similar quantity called longitudal deformation modulus (in Russian literature, they call it модуль продольных деформаций) and it is denoted D. What is that quantity and is it the same as Young's modulus?
Comment: Show us some *equations* using your D. Then non-Russian-speaking engineers might be able to answer the question.
Answer: Young's modulus is the elastic constant for a bar of a finite thickness which is free to contract or expand laterally as it is stretched lengthwise. In terms of the Lame' constants $\lambda$ and $\mu$ (see https://en.wikipedia.org/wiki/Lamé_parameters)  we have
$$
E= \lambda(1-2\sigma)+2\mu=\mu \frac{3\lambda+2\mu}{\lambda+\mu}
$$
where
$$
\sigma=\frac 12 \frac \lambda{\lambda+\mu}
$$
is Poisson's ratio --- the ratio of lateral contraction to lengthways stretching.
The elastic constant for longitudinal stretching of a sytem that is not allowed to shrink sideways as it is stretched  - for example the longitudinal "p" waves in an earthquake --- is different. It is given by $\lambda+2\mu$, so the velocity of longitudinal $p$-waves is
$$
V_p = \sqrt{\frac{\lambda+2\mu}{\rho}}
$$ where $\rho$ is the density.
Comment: Then if the elastic constant for longitudinal stretching is the same as longitudal deformation modulus, it should not be easily possible to measure it directly but typically only from the p-wave velocity. But the paper I read said they measured the value by electrotensometry during uniaxial compression (where the sample is allowed to change in tranversal directions).
Comment: If this is what the Russian text means, then the longitudinal modulus is related to $E$ and $\nu$ both of which are easy to measure in a uniaxial compression (or tension) test. The relationship would be something like $D = \dfrac{E}{1-\nu^2}$ - if this really is the meaning of $D$, of course.


Late Yom Hatzmaut

Question: What is the rule: when is Yom Hatzmaut moved from the fifth of Iyar to an earlier or later date?
Answer: To remove any possibility of observances of either Yom Ha'atzmaut or the preceding day's Yom Hazikaron spilling either forward or back into Shabbat and thereby causing public Shabbat desecration, the Israeli Chief Rabbinate determined that Yom Ha'atzmaut should never fall on a Shabbat, Sunday, Monday, or Friday. So, if 5 Iyyar is on a Friday or Shabbat, the holiday moves back to Thursday. If 5 Iyyar is on a (Sunday [impossible in our current calendar] or) Monday, it moves forward to Tuesday.
Comment: And the position of the Rabbinical Council of America is that Diaspora Jews should observe Yom Ha'atzmeut the same day that Israelis do so. http://www.rabbis.org/news/article.cfm?id=105487
Comment: Though some notable rabbis, both in Israel and the Diaspora, differ and insist on strict observance on the 5th of Iyar no matter what; (see http://torahmusings.com/2011/05/technology-halakhic-change-and-yom-ha-atzmaut/); but the standard official position is as Isaac stated, whether in Israel or outside.
Comment: @AriBrodsky Moving it back to Thursday would place Yom haZikaron on Rosh Chodesh. Isaac's extrapolation is very well based.
Comment: On what basis do you say that if 5 Iyyar falls on a Sunday, Yom HaAtzmaut is moved to Tuesday?  I could just as easily assert that if 5 Iyyar falls on a Sunday, Yom HaAtzmaut is moved to the previous Thursday, and we would both be correct, because (as you correctly state) the current calendar does not allow 5 Iyyar to fall on Sunday.  My point is that there is no official statement about what happens to Yom HaAtzmaut in that case, because the case never occurs.

Late Yom Hatzmaut


Custom Auto Increment field in Umbraco

Question: I have worked with my self programmed CMS but new on Umbraco. I am working on Umbraco 4.7 with .net framework 4 and want to create a content structure somewhat like this

MaleModels
|--------------Model (Can be multiple)
                 |----------- Model Id (Problem)
                 |----------- Name
                 |----------- DOB
                 |----------- etc...

I need to create node for each Model and want to assign a unique Model Id to each model but can't find any data type that can be used for Auto Increment field (As I do when programming custom .net code with SQL). I know that I can use @pageId, but I want Model Id to start from 100 and with single increment for each Model only.
Need Help...
Answer: One option is that you could handle the Document.AfterPublish event in a custom library that could add the auto increment value to a "autoID" field after creation and save/publish it again.  You may need to keep a counter of the current increment id value (say in the "MaleModels" node above) so you don't have to query all of the Models each time to find the highest ID.
Here's a blog post about events in Umbraco that may help with the details: http://www.bo-mortensen.dk/2011/10/umbraco-more-event-goodness/
Comment: Thanks for your reply, after some more analysis, I got an idea. Shouldn't I create another table **ModelInformation[ModelId PK (AutoIncrement), ModelNodeId (FK from cms_Content)]**, and as stated by you I can use Umbraco event model to perform this task. Is it the **cms_Content** table that stores nodeIds of Umbraco nodes. If it is then I can use Umbrao event model to get "created node Id" and store it in ModelInformation table. Next time whenever a Model node is encountered, I'll take its nodeId and find the corresponding ModelId from ModelInformation table.
Comment: Yes, you could certainly add another table and store it that way as well.  Would it be important to see that ID in the Umbraco Admin area?  You may want to create a simple UserControl DataType that displays the ID on the page in the admin area.
Comment: Yes, it will be good to show model Id in admin area, actually in a label. In fact, I have found a good project on [www.nibble.com](http://www.nibble.be/?p=24), Do you also have something to share?
Comment: This umbraco.tv video is a good tutorial: http://umbraco.com/help-and-support/video-tutorials/developing-with-umbraco/data-editors/creating-a-custom-datatype-using-the-usercontrol-wrapper
Comment: Tim's blog a nibble is a great resource as well.
Comment: Thanks for sharing link, I think you should post some free link for me and may be for future visitors, as the **link above requires an Umbraco premium subscription.**
Answer: Why don't you create "Custom User Control" which has database and you can create first column as Auto-incremental and second column as NodeId, once you done that please add that into the database on Page_Load() event make sure you check if NodeId exist then don't insert record.
Now create as DataType in Umbraco then use as property, User Control will get Auto-incremental number when you create node that user control will insert record with NodeId and will generate Auto-incremental and display into the page_load() into <asp:Label>,
It will heat every time page load so what you can do is that you will need to check every time into you database is NodeId exist or not if it exist then don't insert otherwise insert into the database that way you can create your auto-incremental,
You need to bare in mind that will be heating every-time database just make sure with performance wise you need to look into it.
if you have further question please do let me know.
Thanks
Ankur

Custom Auto Increment field in Umbraco


How can I make Notepad++ "save as" default to a file extension based on the selected syntax highlighting language?

Question: Let's say I write a Java class in Notepad++. I choose "java" in the language menu, and when I save the file it will automatically be a .java file. Well atleast it used to. I just reinstalled notepad++ and this doesnt work anymore. Anyone know how to fix it? Thanks in advance :)
Comment: Can you look at your language settings file? (C:\Users\User\AppData\Roaming\Notepad++\langs.xml) There should be an entry with **<Language name="java" ....** - the extension should be ext="java"
Comment: Thanks. It was already correct, so I guess the problem lies somewhere else
Answer: I'm not familiar with it saving dependent on the syntax but I know that you can change the default file type that it saves as. If that would work for you, there is already a thread about that here and how to change it.
How can I change the standard "save as" filetype of Notepad++?


Professor does not provide feedback, grades, or lecture - Do I have the grounds to file a complaint?

Question: I am in a graduate level (online) mathematics course. At the beginning of the course, the professor told us to post all of our homework solutions to the online learning forum which is open for everyone to see.  While I do not have any issues with this per se, we are not graded on the homework nor are provided any feedback.  The lack of involvement on the professors side has led to many students not even posting worked through solutions (i.e. provide a couple steps and skip to the solution).  Moreover, we are given weekly reading out of the main text (usually a chapter) for which we are supposed to read, then watch the recorded lectures, and finally complete our problem set.  That said, the lectures do not actually cover the reading in the book or provide any worked through examples.  This is a theory based course and none of the proofs are worked through in the lectures either.  The lectures simply consist of the professor reading aloud the theorems and moving on.   The course costs nearly $5k and I am wondering where the value is.  It would seem that the cost of the course is to have access to material, most of which is openly accessible to anyone with internet. I could just as easily buy the book and read it at home for free and get just as much out of it as I am going through this course.  I know this is a bit of complaining on my part but I admit I am very frustrated that this has happened in more than one class.  Do I have any grounds to go "up the chain" and file a complaint?  Is a complaint of this matter likely to fall on deaf ears?
Comment: I'll offer $900! Race to the bottom, anyone? ;-)
Comment: Hmmm. I have a list of 25 Wikipedia articles and YouTube videos on that very topic and I'll be happy to sell them to you for only $1K. Interested? I'll provide all of the other services as well - no grading - no feedback.
Comment: @Buffy $2K and you got a deal.
Answer: Yes, do complain. The value of a teacher is precisely to do things reading books and  watching videos can't do: Answer questions, give feedback, help with gaining insight. If a professor does none of these things, then they're paid for a service they're not providing, and that should concern their employer.
So do go to the department head and complain about it. At the end of the semester, also make sure that you state your complaints in the course evaluation most universities have.
Comment: One should of course keep in mind the very real possibility that not just the course, but the entire online program, is a scam. In that case, I doubt complaining to the "department head" (if there even is one) will be of much use.
Comment: @AaronHendrickson online programs especially master's usually are
Comment: @DanRomik Either way -- if that's the level at which they teach, then they don't deserve to have students. Students complaining about stuff, and putting the reputation of a program at risk, is something that's generally taken seriously.
Comment: @AaronHendrickson Departments need money, people are willing to pay for them. They're cheaper than in-person. That's not to say they're all *bad*, but yes, they're often profitable for the department.
Comment: @DanRomik The thing is its a program from a Tier 1 university.  That said, I still get the impression that it is just a money making scheme...
Comment: @AzorAhai Any insight on why that is? The university I am obtaining my Master's through is not exactly some hole in the wall school.
Answer: While you have the right to complain to a department head or other individual, my first step would be to discuss this with the instructor themselves. In our department, we would expect a student who complained to at least try to informally resolve the issue with the instructor before escalating it up the chain.
If the instructor has a very high grading load, there is a chance that they are not giving full feedback to all students under the misapprehension that the students don't want to engage with the feedback. Perhaps if you reached out to them, they would be happy to work with you on providing more fulsome feedback and helping you develop your skills.
(and, if not --- this would make your approach to the department head or chair even more convincing)


Can't get my refresh rate right

Question: After reading tons and tons of manuals and forums about the problem I need to ask myself, because I can't figure out what's wrong.
In my new PC there's a GTX 660 connected to LG Flatron L1730S using D-SUB / DVI connetor. This monitor is able to work at 1280x1024 with 75 Hz refresh rate and I'm not able to set it anyhow.
I can create a new mode in xrandr but I can't connect it with DVI-I-0 output to which my monitor is connected.
After
xrandr --addmode DVI-I-0 1280x1024_75.00

I get this:
X Error of failed request:  BadMatch (invalid parameter attributes)
Major opcode of failed request:  140 (RANDR)
Minor opcode of failed request:  18 (RRAddOutputMode)
Serial number of failed request:  39
Current serial number in output stream:  40

It's been two days now, and at 60 Hz I get my screen is flickering.
Please, help me get it right.
PS. I use nV proprietary 331.113
Comment: Are you using a converter or a connector?
Answer: Okay, I got what the problem really was - it was related with the connector I used. There's no way to fix it another than changing connector to converter as far as I'm concerned.
Comment: That's why I asked you this 5 months ago... (see above)

Can't get my refresh rate right


choosing is vs are

Question: When using listing something using "and" it's almost always going to require are, but I was wondering if this sentence is correct.
"Money and fame is not the answer."
I question it since I feel like it acts as a group or set and is would be appropriate.
Same with "Using kilograms and grams is a better measurement."
Thanks in advance!
Answer: You've almost answered your own question - if two or more things are grouped together then you can sometimes refer to "them" as if they are one. However, it is not always so clear. It depends on whether you are referring to the collective as a single entity or a group.
For example, you might say:

There is a football team in my town.

"Football team" is the collective noun for a group of players, and you are referring to the team as a whole. However, if you were using the collective noun to refer to the players you would say:

The football team are walking onto the pitch.

This is because the collective noun is substituting for the individuals. It is basically the same as saying:

The players are walking onto the pitch.

When it comes to organisations the rules of grammar differ between British and US English. In BrEng we follow the same rule as above when speaking about organisations, for example:

The BBC is a broadcasting organisation in Great Britain
The BBC are currently filming in London.

Apparently, in AmEng organisations are always spoken of in the singular.
Referring to your example, I'm not completely sure if "money and fame" should be treated as one - they may come together, but not necessarily. However, in your sentence there is only one "answer", which would suggest that it has already been established "money and fame" are collectively "an answer" (singular), otherwise you would have to say "money and fame are not answers".
Consider these examples referring to "diet and exercise":

-"What do you think is the best health regime?"
  -"Diet and exercise is the best regime for me".

This seems right because "diet and exercise" are being used collectively to describe the person's health regime.

-"What do you think is important to maintaining good health?"
  -"Diet and exercise are very important".

This seems correct because diet and exercise are being cited as two individual factors.
Using the other example in your question, you could say "kilograms and grams are units of measurement" because they are both units individually; however they are also part of the same system of measurement, so you would say "kilograms and grams is a system of measurement".
Comment: @JasonBassford It was a typo. I have corrected and added the link I referred to.
Answer: Money and fame is not the answer - yes, this sounds ok, because "Money and fame" is an expression that can act as a singular concept. However, Using kilograms and grams is a better measurement sounds wrong because the *using* of these units of measurement is not a *measurement* itself.
Comment: Well, OK, but how about "Using kg and g is a better *practice*" ? That sounds fine. The "and ... is" was really user86098's point. [look, I put "is-was" in a sentence]
Comment: It is not as simple as this answer suggests. It depends what the collection you are referring to represents. Using the example in this answer you could say "kilograms and grams *are units* of measurement", because they are both units individually; however they are also part of the same *system of measurement*, so you would say "kilograms and grams *is*  a system of measurement".

choosing is vs are


Will water cool faster in an earthen pot if wetted externally?

Question: If we put water in an earthen pot then water is being absorbed and it reaches  the surface of the pot and then water evaporates and makes inside water cool. So is it right that if we wet the earthen pot  ourself then, will the process of cooling of water  become shorter and water will cooled down faster?
Answer: If you put earthen pot in water before water inside pot reaches surface, then
Yes, cooling will become faster.
For instance, your hot utensil cools when plunged in water.
But, final temperature of water inside pot is independent of above two ways of cooling.


Get rid of *~ files in KDE editors

Question: All the KDE based editors (Kate, KWrite, Kile, etc.) tend to produce recovery (?) files that are named like the edited file with a tilde at the end. The annoying thing is that these files are left even after I quit the editor. How can I disable this behaviour? I don't mind having these while I am editing (if they help with anything), but I don't want them after I finish.
Comment: Just a thought... you may not want to do that. Sooner or later it will hapen that you'll erase or overwrite the file unexpectedly (and that happens usually when you DON'T have the file open). At that point, these are the only ones that can save you. All the *nix editors do that for a reason - better safe than sorry. It's standard to have `-B` switch aliased in `ls` so you don't even notice them until you need to find them.
Answer: Go to Settings > Configure > Editor Component > Open/Save > Advanced, and uncheck the box next to local files under "Backup on Save".

Get rid of *~ files in KDE editors


venting a range hood outside on our cedar cabin

Question: i need to vent our range hood outside on our cedar cabin and it is on the front of the house we would like it to be as inconspicuous as possible I can not find a vent that would work well with a cedar cabin
Answer: As long as the outside part focuses the air down like this one instead of straight out like this one, you can build a wood enclosure around it. It will still be an "add on" but if you stain it to match the surrounding area it shouldn't be so obvious and won't look so out of place.
Answer: @kristi okane. Is there a cabinet above your stove in which a pipe could be run up above ceiling and out and down through soffits or eave?


Windows does not boot after dd to new disc

Question: Because I want to use a new hard drive, I copied windows like described in https://wiki.archlinux.org/index.php/disk_cloning with dd if=/dev/sdb2 of=/dev/sda1 status=progress. The partition of windows (7) now seems to be working fine, I can open it, view files, and so on.
With my normal ubuntu, I afterwards ran sudo update-grub and windows was found like normaly. Unfortunately, if I choose windows in the grub menu, it gets stuck at showing an underscore and does not boot.
Is there any way of debugging this issue? Since Windows seems to do nothing, I do not get any logs or hints, what I could do with the partition.
Comment: Shouldn't you have copied the whole disk instead of just single partitions? Partition table might need an update/fix perhaps.
Answer: You have to fix Windows 7 boot, so it can boot from its "new" disk by itself.

Fix MBR and partition boot record using bootsect.exe
Fix BCD using bcdboot.exe

Alternatively use bootrec.exe from recovery environment.
Also - fix Windows 7 boot using Startup Repair.
Note: GRUB can chainload Windows only if Windows can boot by itself.
Answer: Update!!!
How to start windows 10 after restored or cloned with dd on ubuntu?
Issue: reboot loop
Solution was: F8 key troubleshoot startup option then more options at the bottom. Microsoft was cheeky to hid this here :)
Use SAFE MODE for the first start after dd and you will be the star.
Good Luck


Where can I find the unicode symbols for Mac functional keys? (Command, Shift, etc.)

Question: Is there a list of key-symbols that I could reference?
Comment: There's a nice table here: https://acrobatfaq.com/atbref5/index/KeyboardShortcuts/UnicodeCodesforKeyboards.html
Answer: If you are talking about something like this: ⌘ (the ⌘ key), then you are looking for this chart:
HTML Entity     GLYPH  NAME
              Apple
⌘         ⌘      Command, Cmd, Clover, (formerly) Apple
⌃         ⌃      Control, Ctl, Ctrl
⌥         ⌥      Option, Opt, (Windows) Alt
⇧         ⇧      Shift
⇪         ⇪      Caps lock
⏏         ⏏      Eject
↩         ↩      Return, Carriage Return
↵ ↵ ↵      Return, Carriage Return
⏎         ⏎      Return, Carriage Return
⌤         ⌤      Enter
⌫         ⌫      Delete, Backspace
⌦         ⌦      Forward Delete
⎋         ⎋      Escape, Esc
→ →  →      Right arrow
← ←  ←      Left arrow
↑ ↑  ↑      Up arrow
↓ ↓  ↓      Down arrow
⇞         ⇞      Page Up, PgUp
⇟         ⇟      Page Down, PgDn
↖         ↖      Home
↘         ↘      End
⌧         ⌧      Clear
⇥         ⇥      Tab, Tab Right, Horizontal Tab
⇤         ⇤      Shift Tab, Tab Left, Back-tab
␢         ␢      Space, Blank
␣         ␣      Space, Blank

You also can copy the glyphs directly!
Comment:  globe with meridians
Unicode: U+1F310, UTF-8: F0 9F 8C 90
Comment: What about the new globe key aka The Artist Formerly Known As `fn`? Which unicode character is that?
Comment: U+1F310 is not a glyph though, it's an emoji.
Answer: There is no need for third-party apps. Press CTR + SHIFT + Space to bring up the built-in Characters popup and use the search field to type the unicode name of the character, e.g.:

place of interest → ⌘ [Command]
option → ⌥ [Option]
arrowhead →  ⌃ [Control]
upwards white arrow →  ⇧ [Shift]
upwards white arrow from bar →  ⇪ [Caps Lock]

✔ You can also use it to insert emojis.
 Click the top right icon to get the extended version of the dialog.

If you right-click a character the Get character info popup will be shown from which you can copy to clipboard the name and the unicode code-point in decimal notation, i.e:
⌘ PLACE OF INTEREST SIGN Unicode: U+2318, UTF-8: E2 8C 98

To use it in your HTML prepend the unicode entity escape prefix and append the semicolon, i.e. 2318 ⇢ ⌘.

You can click the ⚙ (or 3 dot) button > Customize List and enable additional unicode characters groups, including Code Tables > Unicode which will show the full unicode table grouped by categories.

The ⌘ ⇪⌥ ⏎  symbols are grouped under the Technical Symbols category which you can enable for quick access as shown below.
Comment: On my Mac (M1 Max MBP) running the latest (12.3), the pop up **can** be tied to the "world" / function key  via System Preferences => Keyboard => Keyboard => Press  to => a drop down list with four options.
Comment: Oh that's a super intuitive name for it: place of interest. I just wasted 20 minutes of my life. Thank you.
Comment: On macOS Ventura (13.6.4). In the menu bar (if you've "show Input menu in menu bar" activated), there's a "Show Emoji & Symbols" option. If you only see emojis, click on the top right icon to switch to the "character viewer" (cf. image in the answer).
![Show Emoji & Symbols](https://i.imgur.com/gPvXROK.png)
Comment: @ccpizza ?!? ♂ Why are you answering that to me? How is that related to what I said? And what you assume is wrong: I don't have multiple input languages (and never talked about that). I pick more often emojis that I switch languages (on my mobile devices). I configure F* to be the defaults and short press Fn as show emojis. I don't have  on my (old) MacBook. What's the difference with Fn?
Answer: Events.h defines constants for the menu glyphs, but not the code points used to represent them. There are several unofficial lists like Keyboard icons & terminology - Ask Different Meta or this one posted on an Apple mailing list.
CajunLuke rolled back my edit to daviesgeek's answer, so here's another list. Differences compared to the current revision of the other answer:

Formatted as CSV
Added ⌧ and ␣
The numeric character reference for the left arrow key was wrong
Included named character references added in HTML5
Removed uncommon variants like ⏎ and ␢
The numeric character references are in hexadecimal

⌘,⌘,,command
⇧,⇧,,shift
⌥,⌥,,option
⌃,⌃,,control
↩,↩,↩,return
⌤,⌤,,enter
⌫,⌫,,delete
⌦,⌦,,forward delete
⌧,⌧,,clear
⇥,⇥,⇥,tab
⇤,⇤,⇤,backtab
␣,␣,␣,space
⎋,⎋,,escape
⇪,⇪,,caps lock
⏏,⏏,,eject
⇞,⇞,,page up
⇟,⇟,,page down
↖,↖,↖,home
↘,↘,↘,end
←,←,←,left
→,→,→,right
↑,↑,↑,up
↓,↓,↓,down

Comment: @CajunLuke Decimal code points are less common in other contexts; for example you can't search for them in Character Viewer. CSV is easier to parse for use in temporary scripts, easier to output, and easier to convert to an HTML table.
Comment: What's better (also) about hexadecimal is that one need not convert to use Apple's "Unicode Hex Input" keyboard to put the character into a document.  All my files (including web pages) are in UTF-8, so using the actual character instead of HTML entities makes my editing more WYSIWYG.
Comment: The reason I rolled back your answer was primarily formatting-related. CSV isn't real useful on a webpage. I added the characters you said we missed. (Which we did miss, as I used the screenshot that had been there as a reference.) If I got the number wrong or you want to add the HTML 5 named references, please edit those parts.
Comment: Also, what's better about the hexadecimal versions? (TBH, I didn't know you could do HTML literal references in hex.)
Answer: I like to use the widget...
CharacterPal

When you hover over a symbol, you can see its coding.
Copy a symbol to the clipboard by clicking on it. (This will copy the coding.)

The widget offers access to various character sets: Keyboard, Math and Science, Greek, ...
Comment: I would also update this with the `control+command+space` shortcut added in OS X also has a "technical" symbols added
Comment: link is broken :(
Comment: @Downgoat, you mean ⌃⌘␣ shortcut? :)
Comment: @pcperini You might also be interested in [this awesome tip](http://meta.apple.stackexchange.com/a/1282/13414) by user stuffe.
Answer: If you're using TextExpander (and if not, why not?! It's only $45. ), you can just import the "Keyboard" snippet group from Dr. Drang (see the second part of the post) and get the symbols you're likely looking for:
To insert   Type    Key name
    ⌘       ;cmd    Command
    ⌥       ;opt    Option
    ⇧       ;shift  Shift
    ⌃       ;ctl    Control
    ⇥       ;tab    Tab
    ⌫       ;bs     Backspace
    ⌦       ;del    Forward Delete
    ⌅       ;enter  Enter
    ↩       ;return     Return
    ⎋       ;esc    Escape
           ;apple  Apple
    ←       ;left   Left Arrow
    →       ;right  Right Arrow
    ↑       ;up     Up Arrow
    ↓       ;down   Down Arrow
    ␣       ;space  Space

He also has a few other interesting "set of snippets" you might want to have a look at:

Currency icons and Fractions - See here for info.
Miscellaneous Symbols - see here for info.

Hope this helps!


Ubuntu Server, listen for commit on external SVN repository?

Question: I have a Subversion repository which my team and I use for source control on a web application we are building. I would like to be able to have every commit to that repository automatically publish to our testing server. I have checked out the repository to a working copy on the server... is there any way to listen to the repository on the server so that every time somebody commits to the repository I can run a svn update?
Answer: Take a look at post commit. Here's an example.
Comment: Is there any way to implement that on the client side instead of the server side? I don't have direct access to the server where the repository is hosted, so doing a server-side hook will be difficult.


When can I assume that a variable is exogenous?

Question:
I'm looking for the effect of nutritional coffee breaks on MBA performance, and I found that the change to a healthier catering increased the performance of MBA students. Additionally, I want to see if **more exposure to nutritional meals** affects more or less these students' test scores. To do that, I want to use **attendance to measure the intensity of the treatment** (if you attended more, you were more exposed to the treatment). Still, given that the healthier snacks might affect attendance, I first obtain the effect of healthier on attendance, estimating a precise zero. Consequently, can I use attendance as a measure of intensity? or even if I find that healthier coffee breaks do not affect attendance, I should assume that it is endogenous. If the aforementioned answer is correct, can you explain to me why?
Thank you very much.
Answer: $Performance_i = \beta_0 +\beta_1 Attend_i +\varepsilon_i$
It may be that healthier snacks do not affect attendance, but I would be very concerned making an assumption of the form $Cov(Attend_i, \varepsilon_i)=0$. Students who are more likely to perform well are also probably more likely to attend. i.e., there could be an omitted variable, $Motivation_i$ such that $\varepsilon_i =\beta_2 Motivation_i +\eta_i$.
Then $Motivation_i$ is probably correlated with both attendance and performance.
This is tricky. How are you measuring performance? Test scores? Or something else?


The number of non isomorphic groups in Cext(G,C_p)

Question: Let $p$ be a prime number, $C_p$-cyclic group of order $p$, and $G$ an elementary p-group of order $p^n$. Let us denote by Cext$(G,C_p)$ the group of all central extensions of $C_p$ by $G$. Is the number of non isomorphic groups in Cext$(G,C_p)$ known as a function of $n$?
Comment: You have not made it clear in your question whether you are looking for extensions with normal subgroup $C_p$ and quotient $C_p^n$, or the other way round. The expression "extension of $A$ by $B$" is used roughly equally often with both of those meanings.
Comment: Central extensions up to isomorphism would be classified by $H^2(C_p,G)\cong G$ whose cardinality is $p^n$. The non-isomorphic groups are probably classified by $H^2$ up to scalar operation of $C_p$. So I guess the answer is $n\mapsto p^{n-1}$.
Comment: @MatthiasWendt When $n=2$ the answer is 4 regardless of $p$, while you claim $p+2$. (There are 5 isomorphism types of groups of order $p^3$ and all occur except the cyclic one.)
Comment: This question and it's answer might contain some useful information: http://mathoverflow.net/questions/75170/counting-isomorphism-classes-via-extensions?rq=1
Comment: Sorry, the arithmetic was wrong. The non-trivial extensions seem to be classified by $\mathbb{P}^{n-1}(\mathbb{F}_p)$ whose cardinality is $\sum_{i=0}^{n-1} p^i$. And then there is the trivial extension, one more. Sorry.
Comment: Maybe you can extract the answer from results in the article "Groups of prime power order with derived subgroup of prime order", by Simon Blackburn in Journal of Algebra 291, 1999.  The number of groups of order $p^n$ described in Blackburn's title does not depend on $p$.  I guess you will find the same for your groups, as Yves Cornulier pointed out above in the case $n=2$.
Comment: @YvesCornulier: interesting. So the number of isomorphism classes of central extensions depends on $p$, but the number of isomorphism classes of group structures does not?
Answer: I voted to close because I was unsure which way around the extension went but, as Yves said, the question is almost trivial if $C_p^n$ is the normal subgroup.
So, suppose that $N \unlhd G$ with $N=C_p$ and $G/N \cong C_p^n$.
Recall that a $p$-group of this form is called extraspecial if $N=Z(G)$. It is a standard result that extraspecial groups have order $p^{2k+1}$ for some $k \ge 1$, and that for each $p$ and $k$ there are exactly two isomorphism classes of extraspecial groups. (They all arise as central products of extraspecial groups of order $p^3$. For $p$ odd, one of these groups has exponent $p$ and the other does not. For $p=2$, they are central products of $D_8$ and $Q_8$ and the isomorphism type depends on the parity of the number of $D_8$s or $Q_8$s.)
For each $k \ge 1$, we can define a group $S_{p,k}$, which has order $p^{2k+2}$, and is a central product of an extraspecial group of order $p^{2k+1}$ with $C_{p^2}$. It is not hard to show the two types of extraspecial groups give rise to isomorphic groups $S_{p,k}$.
So, in the problem, let $G= \langle z,x_1,x_2,\ldots,x_n \rangle$ with $z \in N$, and order the generators such that, for some $i$, $Z(G) = \langle z,x_{i+1},x_{i+2},\ldots,x_n \rangle$ .
If $i=0$, then $G$ is abelian and $G \cong C_p^{n+1}$ or $C_{p^2} \times C_p^{n-1}$. So suppose that $i>0$.
Then $x_1,\ldots,x_i$ generate an extraspecial group, so $i=2k$ is even. Now there are two cases.
If $Z(G)$ is elementary abelian, then $G \cong E \times C_p^{n-2k}$, where $E$ is extraspecial of order $p^{2k+1}$. For each $k$ with $0 < 2k \le n$, there are two isomorphism types of groups of this form, one for each of the two types of extraspecial group.
Otherwise $Z(G) \cong C_p^2 \times C_p^{n-2k+1}$, and $G \cong S_{p,k} \times C_p^{n-2k+1}$. For each $k$ with $0 \le 2k \le n-1$, there is a single isomorphism class of groups of this form.
Comment: I answered this question some time ago on MO: http://mathoverflow.net/questions/39881/classification-of-p-groups-of-order-pn-with-rank-n-1/39900#39900
Comment: Ah right! I waited some time, hoping someone else would answer. I should have waited a little longer.
Answer: I'd like to thank everyone who has responded to my query.
The question was whether $I(n,p)$= # of non isomorphic groups in $\mathrm{Cext}(G,C_p)$ is known. My impression so far is that it is not.
Regarding discussion, first $\mathrm{Cext}(G,A)$, with $A$ abelian stands for $\mathrm{Opext}(G,A,\text{triv})$, hence by the standard convention $A$ is a normal subgroup of extension.
The number in question $I(n,p)=\lfloor\frac{3n+2}{2}\rfloor$ for odd $p$. The reason for exclusion of $p=2$ lies in the fact that $H^2(G,C_p)$ fits into the exact sequence
$$0\to\widehat G\to H^2(G,C_p)\to\mathrm{Alt}(G)\to 0,$$
where $\widehat G$ is the dual group, splits up as $\mathrm{Aut}(G)$-module iff $p$ is odd. I also show, as a consequence of a general theorem on abelian extensions of Hopf algebras, that the so-called weak isoclasses of some previous posts coincide with isoclasses of noncommutative extensions. Commutative extensions labeled by $\mathrm{Ext}(G,C_p)$ are also in bijection with the orbits, this is trivial. It follows that one has to classify the orbits of $\mathrm{Aut}(G)\times\mathrm{Aut}(C_p)$ in $H^2(G,C_p)$. Roughly speaking, for a pair $(f,\alpha)$ its invariant is $(\ker f,\text{rad}(\alpha)$. From this one gets the number.
George Glauberman seems to have a proof that the formula for $I(n,p)$ holds for $p=2$.
Details can be found at arXiv:1211.5621, look up the latest version (should appear shortly)
Comment: You say it is not known, but as Steve D pointed out in his comment to my answer, the question was answered completely in September 2010 in http://mathoverflow.net/questions/39881. The argument there is more or less the same as in my answer, and it covers all primes, not just odd primes.
Comment: I agree the number in question should be easy to derive from Steve D's or your argument. My solution is along the lines of Matthias Wendt post(s) and earlier posts on this subject, and is complimentary to your.


Is there a way to visualize the limited randomness of an algorithm?

Question: Take the R runif function for example.
 It sure is a very performing pseudo-random generator. Even if I don't really know what it means I think I read somewhere that it will produce uniformly distributed variables up to more than 600 dimensions (based on the default Mersenne Twister).
Apart from simulating an extremely large number of observations to actually see that this not absolutely random, is there a way which will not rely on very heavy computing to see its limited randomness? More generally, is there a " simple test" that even the current best PRG fail to pass?
Comment: I don't think such a test exists. A famous set of tests are the https://en.wikipedia.org/wiki/Diehard_tests
Comment: If it were easy to show that `runif` does  not produce independent, identically distributed uniform random observations, then a different algorithm for `runif` would have beeen implemented.
Answer: Some years ago the multiplicative congruential generator $r_{n+1} = ar_i \;(\!\!\mod d\,),$ with
$a = 65539, d = 2^{31}$ was proposed (and used for a while) to generate numbers
$u_i = \frac{r-.5}{d-1},$ intended to be essentially independent and identically distributed on $(0,1).$ However, when triads of these numbers are plotted in the three dimensional unit cube, it can be seen that the points fall in only a few
parallel planes.
Two plots of points of this generator are shown below. At left, is a plot of
points $(u_i, u_{i+1}),$ generated points look random; at right, a thin veneer from
the front face of successive points plotted in the unit cube shows edges of
the few planes on which all points lie.
a = 65539;  d = 2^31;  s = 10
m = 40000;  r = numeric(m);  r[1] = s
for(i in 1:(m-1))
   { r[i+1] = (a*r[i]) %% d }
u = (r-.5)/(d-1)
u1 = u[1:(m-2)];  u2 = u[2:(m-1)];  u3 = u[3:m]

par(mfrow=c(1,2))
 plot(u1,u2, pch=".", xlim=0:1, ylim=0:1,
      main="Unit Square")
 plot(u1[u3 < .01], u2[u3 < .01], pch=".", xlim=0:1, ylim=0:1,
      main="Face of Cube")
par(mfrow=c(1,1))

Nowadays a proposed pseudorandom number generation algorithm is typically
subjected to a 'battery' of tests before it is implemented for
practical use. These tests are tasks known to be difficult
to simulate, and include tasks that previous unsatisfactory generators
have not been able to handle.
Comment: Nice! Came here to see this. I remember the first time a friend simply plotted a large string of pseudorandom numbers into a square gif. It was instructive, as was walking through a variety of pseudo-RNGs.
Answer: I believe R uses a Mersenne Twister.  It's good, it's widely used, but it's not clear that it's "the best".  As BruceET mentions, there are test suites.  Diehard is kind of old, and TestU01 incorporates many of its tests and more.  There are a couple of tests in TestU01 that the standard Mersenne Twister fails, because it does exactly the kind of thing that those tests look for.  The paper at that site and Pierre L'Ecuyer's other papers are good sources.  Melissa O'Neill's paper is very informative in general, and it will give you a lot of information about visualizations.  I list some other resources, including introductory books, in this answer.


ClearCase: Stream maintenance

Question: Who can lock/unlock/obsolete streams (or any other object) in a clearcase project? Do you have to be a privilaged user to perform these operations on streams that you didn't create?
Answer: The cleartool lock man page does mention:

unix: type/object owner, VOB owner, root
Windows: type/object owner, VOB owner, member of the ClearCase administrators group (which is the "privilege user": see "About ClearCase privileged users on Windows")

ClearCase privileged user is a designation referring to a user account that is a member of the clearcase group, which is granted ClearCase administrator rights when working in Full ClearCase.
  Members of the clearcase group are granted special ClearCase rights.

Regarding Stream, a lock -obsolete Stream:xxx might be your only way to "remove" a Stream (especially if baselines were already created on it): see "Removing a UCM stream that has a delivered baseline".
Here are some examples for locking multiple instances of a same type of object.
To be sure a lock has actually worked, use the -fmt "%n %[locked]p\n" format when listing Streams:
cleartool lsstream -obsolete -fmt "%n %[locked]p\n" -invob vob

The OP Raihan adds in the comments:

According to the ClearCase documentation it it recommended to lock a stream before creating a baseline to prevent users from delivering during the process.
  Isn't it overkill for a 'Project Manager' or 'Integrator' to have the root privilege who is managing a single UCM project (not necessarily created by him)?

Two things:

one, that means locking a stream with the -nuser option, in order to allow the integrator to perform operations (like making a baseline) on that stream.
two, if the integrator is not the owner an in... "integration" stream, then he/she asks the ClearCase administrator to give him/her the ownership of said Stream.

cleartool protect -chown integratorLogin stream:aStream@\aPVob
Comment: According to the clearcase documentation it is recommended to lock a stream before creating a baseline to prevent users from delivering during the process. Isn't it overkill for a 'Project Manager' or 'Integrator' to have the `root` privilage who is managing a single UCM project (not necessarily created by him)?
Comment: Thank you. So that means there can't be more than one integrator managing the same UCM project.
Comment: @Raihan: correct, especially when it comes to locking a Stream. For other operations, you have some extended policies like https://www-304.ibm.com/support/docview.wss?uid=swg21147119 (`POLICY_CHSTREAM_UNRESTRICTED`), but it isn't for locking operations.
Answer: Far as I remember, you have to be one of the following:

Stream owner/creator
VOB owner
Member of ClearCase group
root (in UNIX \ Linux)

You may get further details by cleartool man lock
Comment: What is `ClearCase group`? Is it a OS user group?

ClearCase: Stream maintenance


Is there a HARD counter to Riven?

Question: I find that Riven can do at least decently in every lane if played properly, is there actually someone who can counter her reliably?
Answer: According to the Doombrew Riven guide on LoLPro, Renekton is the hardest champion for Riven, as he counters her ability to get in and out on small exchanges and can out-sustain her with Cull the Meek.
Link is as follows: lolpro.com
Answer: There are no champs who can really be considered a HARD counter to Riven. Some champs that do well against her are Olaf, Garen, Renekton, Teemo, Nidalee and Kennen. Jax and Irelia can do well after a certain level as well.
I'd recommend goldfather8's guide on solomid.net to learn how to play or play against Riven. He goes into each matchup in detail, it'll help you understand how each champion can overcome Riven.
The main reason why there is no real hard counter to Riven is that she scales really well, has cc, has a shield for sustain, has damage from abilities and auto attacks (can't be hard countered by Teemo blind), and she has high mobility to escape bad situations.
Answer: Teemo - Why?

He can kite ANYONE. If Riven tries to close the gap between you and her, you can outrun the hopping.
Teemo bullies any melee champion top lane, and even more if they rely on autos for their damage.

Its really easy too, just poke her like Teemo does, and kite her when she attempts to fight you. Hope this helps ;)
Comment: Actually, Teemo's blinding dart range is equal to Riven's E>Q Combo which can close the gap pretty easily.
Comment: Not great advice, try matching Teemo up to Riven or Renekton and you will be crushed the second they hit level 2.
Comment: I agree with this. But: you have to poke occasionally to wear them down and don't extend. Riven (and Renekton) don't worry me as Teemo in top lane especially with, say, Haunting Guise for some HP. E is better than Q though
Answer: Olaf, would be the hard counter if there was one, since once he hit level 6, He should never be killed by Riven at all. You just need to wait for riven to dash to harass you, and E her and walk away, till 6 when she dashes in, you can ult, when she stuns, and then hunt her down, since not factoring in flash, She has no way to stop you from killing her.
Comment: But considering Olaf's early game isn't very strong against Riven, I wouldn't say he's a hard counter. I've only barely won against most Rivens and that's relying on the extra heal from armor and 5 pots.
Comment: ^Agreed, he's a good lane partner to help counter Riven, but I wouldn't call Olaf a hard counter. It's very situational.
Answer: Riven's health regen has been nerfed which makes poking and kiting a good counter if you have some range. That is, her sustain is lower now.
She can't go head to head after wearing her down. Even if you're playing Teemo top lane
Bottom lane, a typical ADC and support will poke and kite her out of lane.
Patch notes
Answer: There is no "hard" counter to Riven, but some dudes to decent against her.
Olaf and Rumble are pretty much a skill match up, Olaf can beat Riven pretty hard if played correctly, so can Rumble if he gets a little help from his jungler.
Irelia looses early to Riven, but outscales her after 15 mins even if Riven has several kills more.
Malphite and Udyr to pretty good against Riven, and while Malph just outfarm/scales Riven, Udyr beats Riven if played correctly.
Answer: I just smashed a Riven with Volibear. He has an monstrous early game, and that's what you need to shut her down.
Answer: WW is a hard counter if you build first iteam frozen heart.
same on olaf (but only if you build frozen heart on olaf ww is stronger than olaf vs riven)
and jax is a strong counter as well

Is there a HARD counter to Riven?


Should we provide form navigation in 2 step forms?

Question: It is said that multi-step forms should have form navigation in them. But is it also needed in 2-step forms?
Comment: I'm not sure I understand your question. You want to know if in the last step of a multistep process you should add a back option, links to the other steps or breadcrumbs?
Comment: No Madalina. My question is whether I should tell the user beforehand that there are two steps in this form when there are only two steps. If I do so, wouldn't it mean providing excess information? Nevertheless, Pavel Ryzhov has a point. We should still providethe navigation.
Answer: Yes, the number of steps should be clearly indicated.
When a user fills up a form, he or she doesn't know that there are just two forms. Such awareness affects positively on user's decision whether or not to proceed with filling up a form.
If the steps are small and can be combined, perhaps, it can be an even better option. In this case, don't forget to update the title of the button from "Next" to "Finish", that will indicate that the form contains no additional steps.
Comment: Hey Pavel, can you share any references e.g. books, studies, or online blogs that talk about two-step forms? I too feel the same but am struggling to find any way to convince my team.
Comment: @VineetArora, I'd love to, but this answer based only on my own experience as a user, thus there is no external source.


Can employer retrieve emails sent using work email after you delete them in outlook?

Question: If I delete a bunch of emails from outlook, can my manager still retrieve them and read them? If yes, can they view all the attachments?
Comment: Potentially.  If the emails were there for any length of time they could easily have been caught in the backup cycle and therefore be retrievable.  If you were "being monitored" then it would be possible to forward copies of your emails to someone else without you knowing.  Have you been using your email for things you shouldn't?  ;)
Comment: I guess you know, but just to be sure: if you delete a sent message, it won't disappear from the recipient's mailbox.
Comment: yes, I did something I regret. I'll be fired if my manager finds out, or worse...
Comment: @Mokubai Your comment should be a standalone answer. I think it's at least as relevant to the question as the outlook-specific features, and speaks to the greater point that _anything_ that ever went across your employer's server should be considered possibly recoverable.
Comment: There's also a difference between "can my manager read my email", "can IT pass my email to my manager if asked", "will IT pass my email to my manager if asked", and "can and will IT pass my email to a court if my company is sued because of it". IT may not honour time consuming requests unless ordered to do so by someone quite high up in the company; they may have more important things to do.
Comment: @kuromusha, Wow, what did you do? You violated your contract?
Answer: If you're using Exchange Server then yes, this is easy, any deleted item(s) can be restored by authorized person including attachments within the retention period.
Comment: It is configurable by the administrator.
Comment: Depending on your Outlook version look for "Recover Deleted Items" and you can get an idea of how far back it goes. That portion is considered a feature in case people make mistakes.
Comment: how long is the retention period?
Comment: In many database systems, deleted items are either merely flagged as deleted and ignored, or simply moved to a "deleted items" table. Many others store transactions (differences) which can be rolled back. Emails are/can be required to be stored long-term by law.
Answer: TL;DR: Can they? Almost certainly. Will they? Usually not, unless you give them reason to or they're a particularly bad workplace.
If the emails were there for any length of time they could easily have been caught in the backup cycle and therefore be retrievable in the event that anyone had a reason to suspect you had deleted something that might be important.
If you were being monitored then it would be possible for your IT department to forward copies of your emails to someone else without you knowing.  It is also possible that your boss could have been given access to your email if you were under investigation for misconduct.
Because you used company property whatever you sent could have gone through any number of systems.  Firewalls scanning for corporate secrets, virus scanners, and data protection systems could all have caught a copy or at the very least taken the subject line and a brief excerpt of the email.
Even if your company provides "free" WiFi as a courtesy this could easily be monitored and logged.  Emails used to be sent in cleartext so anyone could read them if they wanted, thankfully encryption is more common in email clients now.
The thing here though is that in most countries giving this level of access would be considered unethical and potentially illegal unless some kind of disciplinary proceedings were under way.  I would consider it "against the norm" for any workplace to attempt recovery or otherwise monitor employees without due reason.  I have heard of places, but those places tend to have Banana Dictator Managers with little regard for the meat-sacks that litter their office and a high employee turnover as a result.
On the bright side, backups often get recycled or purged, logs get erased after a while and people forget.
Comment: And even if backups are not purged, they are rarely used for this purpose, unless there is a concrete suspicion.
Comment: "but those places tend to have Banana Dictator Managers" or happen to be in a heavily regulated industry, where sensitive information can be traded for illegal gains.
Comment: @GolezTrol Aye, I was trying to get to that point in my answer. Any reasonable workplace would trust their employees, let them have at least *some* leeway and privacy and not actively be doing this sort of thing without reason.  They are completely **able** to do these sorts of things, but any ethical management system will not unless they suspect you of completely failing to do your job or have reasons to suspect you are abusing their property or systems.
Comment: @Aron In that case I would argue that you would have clearly been told that "due to the nature of the work **all** communications are subject to active monitoring and inspection" and you would almost certainly not sent any emails of the type that OP appears worried about in the first place.  You would already be aware that such monitoring is commonplace in your business and not need to ask if it is possible after the fact.  I know of places where what you say is the case but assumed from context that this was a "more relaxed" workplace.
Comment: @Mokubai, What does "Banana" Dictator Managers mean?
Comment: @Pacerier A banana dictator is the man at the top of a corporate [banana republic](https://en.wikipedia.org/wiki/Banana_republic) and is basically someone who, rather than value their employees, considers the employees a resource to be exploited. Generally the workplace will have a strong authoritarian vibe with little respect for the workers.  While workers *are* there to do what is asked of them, generally most places work better with some mutual respect between employee and employer.
Answer: Unfortunately, anything you do on a employer laptop is considered property of the company.  I'm sure you signed some sort of agreement when you started, indicating your laptop is the property of the company.
Even if you deleted the emails, your organization most likely will have a comprehensive backup strategy in place to recover anything deleted, even from several weeks back.
Comment: Hardware doesn't really factor into this question and ytour statement would be incorrect in several European countries where personal email for instance is protected against corporate oversight.
Comment: I agree with your first paragraph, but your second paragraph doesn't ring true. I rarely ever see organisations with proper backup retention in place, and even when it is, getting back individual mailboxes or mailbox items are usually way too much work to bother with. Of course, it's not worth the risk to assume that they don't.
Answer: There are multiple ways that email can be retained separate from a backup.  The most common is called Journalling and it has nothing to do with Outlook.  It merely duplicates all incoming messages and stores them in a secured place.  This ensures that if the company is sued, etc., that it has a record of every email sent and received by the company.
In short, you should assume that every email you send or receive, every web page you visit, every porn file you download onto company property will be documented somewhere.  As many of the others have stated these are rarely used unless there's a lawsuit or Intellectual Property at stake.


Star/Point based Image Registration

Question: I am developing an application that stacks multiple frames captured from a CCD camera. The frames are meant to be "aligned" or registered before stacking them. The initial aim is to ask the user for the relevant control points and then figure out if the frames need rotation and/or translation. Eventually, perhaps in the next version, I'd like to be able to detect the stars and cross-reference them in all the frames automatically.
My question is, is there a library that I can employ to register these images i.e. translate and/or rotate? I am using Xcode on Lion and would really prefer a library meant for Cocoa but anything written in C would be fine as well.
Answer: A tracking library such as libmv might work for this, it sounds like a tracking application.

Star/Point based Image Registration


How to merge 2 textures into single SRV

Question: I have 2 textures in 2 different ShaderResourceViews. What's the fastest/least expensive way to merge them into one? I would use CopySubresourceRegion but copying a texture is quite a bit expensive. I'm using DirectXTex toolkit for loading textures.
Comment: I did a quick test on my mid-high end machine and copying 500 1MB textures took 1.891ms.  It's best to avoid spending too much time on these kinds of optimizations until you discover there's a bottleneck through measurement, or you're certain that there will be one based on experience.
Comment: Have you actually measured performance of the copy call?  You say it's expensive, but what are you comparing it to?
Comment: @MooseBoys It's expensive for sure. I have 500 textures to merge
Comment: How expensive?  I wouldn't expect copying 500 textures to take more than 100ms even on the slowest GPUs.  It should be way faster than the time it takes to get them to the GPU in the first place.  Of course I assume you're doing this once at load time, not per-frame.
Comment: @MooseBoys I though it will be more expensive, thanks for your reply.
Answer: You can do the next trick: make a destination texture, set it as render target, draw a quad to it covering all the texture area, in pixel shader make any kind of blending from two (or even more) textures.

How to merge 2 textures into single SRV


Is there any incidence of Portend or fortell (bhavishyavani) in scriptures except Krishna birth?

Question: Is there any incidence of Aakashvaani in scriptures except Krishna birth? Bhavishyavani of something in scriptures?
Comment: There was Akash Vani during birth of Sishupal..
Comment: There is an incident in Sri Ramacharitamanas. The incident took place when Kagabhushundi (as Brahman) had a heated discussion with sage Lomasha and the latter cursed the former to become a crow. Then there was askashvaani that declared Kagabhushundi to be a true devotee of Sri Rama in thought(mana), speech(vachan) and actions(karma).
Comment: I don't know about akashvaani but there is a bhavishyavani in Shrimad bhagwat Mahapurana about Kalki avatar which is yet to be fulfilled. http://www.stephen-knapp.com/kalki_the_next_avatar_of_God.htm
Comment: I vaguely remember watching an episode of Narsimha avatar in one of TV Series, where it was shown that when Narsimha is about to kill Hiranyakasypu, there was an Aakashvani. But no scriptural basis to support this incidence.
Answer: In fact there are lots of incidents. One example occurs in Mahabharata Vana Parva
in the story of Bhageeratha. The sloka is athāntarikṣācchuśrāva vācaṃ gambhīraniḥsvanām । meaning a loud voice spoke from Aakash or Antariksha. You can refer that at https://archive.org/details/mahabharata02ramauoft page 346 (of the document, not the book) sloka 21.


Examples of three dimensional Non Nilpotent Leibniz or Lie algebras.

Question: Can one give me some examples of three dimensional Non Nilpotent Leibniz algebras? Any references to the classification of three dimensional Non Nilpotent Leibniz or Lie algebras will also be helpful.
Answer: Just for Lie algebras: $\mathfrak{sl}_2(\Bbb C)$ (over $\Bbb C$). $\mathfrak{su}_2$ (over $\Bbb R$). The upper triangular matrices in $\mathfrak{gl}_2(k)$ (over your favourite field $k$).
Answer: The classification of all complex $3$-dimensional Leibniz algebras is well-known, see for example here. Like for Lie algebras, there is a version of Engel's theorem to decide whether or not a given Leibniz algebra is nilpotent - see here. In fact, $L$ is nilpotent if and only if all left multiplication operators $d_a$ for $a\in L$ are nilpotent. So we can easily find out the non-nilpotent algebras from the classification list.


Cakephp select from subquery

Question: I'm using a subquery to calculate certain fields

place_id, count(*) as count, IFNULL(AVG(reviews.rating),0) as value

now I want to be able to select these values but don't seem to find out how, only in a WHERE clause...
Answer: take the ids you will get from this query as an array and put it in a find().
$this->Model->find('all',
   array('conditions' => array('Model.id' => $list_of_ids);
if you put an array of Ids in a query, cake automatically builds an query with the correct subquery.

Cakephp select from subquery


Atoms traveling at the speed of light

Question: If an atom was to travel at the speed of light (although impossible), wouldn't the nucleus break apart? I say this because the particles holding the protons together in the nucleus wouldn't be able to reach them and keep the atom together. So even if special relativity was wrong, wouldn't it still be impossible for an object with mass to travel at the speed of light.
Comment: Don't the constituents of an atom (proton, neutron, electron) have mass as well?
Answer: Of course, this is impossible, but you can use it as a thought experiment. You're looking at the behavior at a singularity, so the way to deal with this is to investigate the limit. In this case, you can do that intuitively without the mathematical formulation: Because of the relativity principle, no matter how close you are to the speed of light, for you light still moves with the speed c in either direction. So there is not even a hint of any change. Therefore, in the limit, the to and fro of particles still works the same.

Atoms traveling at the speed of light