Soil prep work for sod installation

Question: Is it ok to till my lawn and prepare it 2 weeks in advance of sod installation? Worried about the difference of "settled" and "compacted".
Comment: Hi! You have a couple of unregistered accounts. Please [register](/help/why-register) one of them, then [merge them](/help/merging-accounts) together, which will allow you to [edit](/help/privileges/create-posts) and [comment on](/help/privileges/comment) any of your posts. Thanks, and welcome to the site!
Comment: can we see your soil health, as it may not be healthy enough to easily support sod, and need to provide a lot of nutrients for the grass?
Answer: It depends what state it is in before you start.
If you disturb the soil to the same depth over the whole lawn, it will settle evenly, and you won't notice. But if you are re-landscaping it and you have 3 inches of depth of tilled soil in some places and 2 feet of new topsoil dumped in others, the longer you can wait before you replant it the better (at least up to 3 or 6 months, not a couple of weeks).
The best natural soil levellers are rain and sunshine. Water fills up the spaces between the soil grains, and as it dries out the surface tension pulls the grains together. But you can't rush that process.
If you try to rush it with a heavy roller, you are right to be worried about compacting the soil too much for the grass roots to get established quickly (i.e. in the first growing season), but again, it depends on your soil type, Rolling that would be harmless on light sandy soil could make heavy clay the same as poured concrete, so far as newly laid turf or grass seed is concerned.
The problem with turf is that is "looks OK" for a few weeks after you lay it whatever you do, but if the turf roots can't penetrate the soil beneath it will never grow well, and a dry spell may kill it completely.
Comment: Thanks that helps. Not planning to roll it. Just had a heavy rain and am going to fill in some low spots and rack the top soil evenly across. Just wanted to make sure the soil wouldn't compact that quickly. It is a clay based soil with about an inch of topsoil added

Soil prep work for sod installation


Disable or lock Google Play on my android phone

Question: How can I disable/lock Google Play on my phone(may be restrict it with a password)? I tried this way and followed the steps given there. But it's not asking any password for free apps.
Comment: You are running the support version of Google Play correct?
Comment: I didnt understand what is support version. When I go to settings in Google Play app, it shows me version as "3.10.10"
Comment: What do you mean *not asking any password for free apps* when you wanted to disable Google Play? Clarify?
Comment: If you want even more controle, you can have a look at some corporate apps. For example: [MobiControl](http://www.soti.net/Mobicontrol/AndroidPlus/) or [SureLock](http://www.42gears.com/surelock/surelockandroid.html)
Answer: It won't ask for a password for free apps since there's no danger of financial loss of any kind, it is a good point however
There are apps on Google Play that can 'lock' certain apps check 'https://play.google.com/store/search?q=app+locker' or something to that effect
This one looks like it does the job: https://play.google.com/store/apps/details?id=com.domobile.applock&feature=search_result#?t=W251bGwsMSwyLDEsImNvbS5kb21vYmlsZS5hcHBsb2NrIl0.
They will enable control of apps via a pin
Comment: There may not be any financial danger!!! But there can be adult apps(free) which kids are not supposed to download
Comment: I have just gone through the link, it locks the installed apps but what i want is stop Google Play from downloading anything
Comment: Oh.. I just got it. I think I can lock Google Play using this app. I will give it a try. Thanks
Answer: From google play download applockr or you can disable the app via settings>apps>all applications then by selecting the google play application and pressing the disable button to disable it until you want to enable it (do the same process but the disable button will be replaced with the enable button)
Answer: I think the explanation on this post is what you need: http://www.android.gs/block-google-play-android-market-from-inappropriate-downloads/
Comment: Please don't use URL shorteners here.  As well, if the link goes down this answer is useless -- please summarize the relevant information in your answer.


Non well founded model of ZF

Question: I read that there are $(M,E)$ well-founded model of ZF that in fact not to be.  However I don't understand in what sense "not really to be ". I think that $(M,E)$ is well-founded  because $(M,E)\vDash (\text{foundation})$ so does "not really to be " mean that any infinite $E$-descending sequence is not an element of M ?
Comment: I'm don't think "in fact not to be" or "not really to be" is English. Are you translating the claim from a different language?
Comment: This question has come up a few times; see e.g. http://math.stackexchange.com/questions/477715/can-a-model-of-set-theory-think-it-is-well-founded-and-in-fact-not-be?rq=1.
Answer: $(M,E)$ satisfies the axiom of regularity if whenever $A\in M$ is a non-empty set, then there is some $B\in M$, such that $M\models B\mathrel{E} A$, and $M\models A\cap B=\varnothing$.
In the presence of choice, this is equivalent to saying that there is no $F\in M$, such that $M\models \operatorname{dom}(F)=\omega^M\text{ and }\forall n, F(n+1)\mathrel{E}F(n)$.
But it could be that such $F$ exists outside of $M$. If you are familiar with ultrapowers (ultraproduct where all the structures are identical), you can show that an ultrapower of $\Bbb N$ with a free ultrafilter over $\Bbb N$ is never well-founded. The same argument will also work for models of $\sf ZF$.
Comment: Thank you for the answer!  To understand more about your answer I have some questions: 1. When you write the intersection of A and B is the empty set do you mean that $\lnot  \exists z\in M (zEA\land zEB)$? and also do $\emptyset^M $ and $\omega^M$ are defined by the same formulas that usually define them in V but relativized to M,E ? ( for example $\emptyset^M $  is an element $x\in M $ such that $\forall z\in M \lnot zEx $) finally is it correct to say that "assuming axiom of choice" is the same that V satisfies this axiom or M satisfies it ?
Comment: Yes to the first question (on all of its sub-parts); $M$ for the second question, since we're interested in something happening inside $M$ (note that the existence of such $F$ always contradicts the axiom of foundation).

Non well founded model of ZF


How to interpret autocorrelation of residuals and what to do with it?

Question: I was wondering what does it mean when time series residuals have autocorrelation? How should I deal with it?
Answer: Since this is a very comprehensive topic, you will have to do research on model checking within the Box-Jenkins framework by yourself, but I try to give a short answer to your short question:
In general, after fitting a time series model (at least you are using a standard model and not assuming a special individual model, where the residuals may behave differently) the residuals should be white noise. So they should have no autocorrelation. If you have significant autocorrelation (you have to test this) and not just one spike at high lag order in your acf/pacf this maybe an indicate that you specified your model wrong. It depends, you could for example plot the residuals along with your other variable in a scatter plot and look, e.g. if there is still a seasonal behaviour, but you should also definitely also test this. If the autocorrelation is significant, yes, this is a problem, since this implies, you missed to include some information. So e.g. your lag order is not sufficient. If the autocorrelation turns out to be not significant, this is not a problem.
So the answer: Test it. See: How to test the autocorrelation of the residuals?
If this answer satisfies you, it would be nice, if you click on the left hook to my post and accept my post as the answer.
Comment: The key part is that if a Box-Jenkins model is correct, the only difference between the model's output and actual data should be random (white) noise. If the difference has a pattern, you've left something out of your model or otherwise mis-specified it. Statistically-significant autocorrelation of the residuals is a pattern -- your model's output differs from reality in a systematic way -- so your model needs work.
Comment: Thank yoy for your answer. I want to know whether the autocorrelated residuals indicate the presence of autocorrelation of independent variables or of the dependent variables? Or, both is possible?
Answer: Following Stat Tistician's suggestion, the solution is to use Regression Model with ARIMA error .
<code>library(nlme)

#create some fake data with AR4 noise
n=500
set.seed(42)
v = arima.sim(list(ar=c(0.2,0.2,0.2,0.2)), n)
x= seq(-3,3,length.out = n)
y = 0.5*x + 2*v + 0.5*rnorm(n)

#fit
summary(gls(y~x, correlation = corARMA(form = ~1, p=4,q=0)))
</code>


Find the splitting field without the explicit roots

Question: Let $f = X^3 + 2X -2$. I want to find the splitting field of $f$ over $\mathbb{Q}$. My problem is that the roots of $f$ are too complicated, see Wolfram Alpha. How can I find this splitting field?
Comment: What is an acceptable description of the splitting field? Note that you can find explicit roots for a cubic equation always..
Answer: The most "concrete" description, I can think of is this: Suppose $\lambda$ is a root of the polynomial $f(X)=X^3+2X-2$. You can infer the existence of this root from Kronecker's theorem, which constructs for every irreducible polynomial $f$ over a field $K$ an extension field $L\supset K$ in which $f$ has a root.
Then using long division, you can express $f(X)=(X-\lambda)(X^2+\lambda X+(\lambda^2+2))$. You can further factor the quadratic $(X^2+\lambda X+(\lambda^2+2))$ by using the quadratic formula $\frac{-\lambda\pm \sqrt{\lambda^2-4\cdot(\lambda^2+2)} }{2}=\frac{-\lambda\pm \sqrt{-3\lambda^2-8} }{2}\in \mathbb Q(\sqrt{-3\lambda^2-8}) $ for your favourite choice of square root in $\mathbb C$.
Then you can express the splitting field of $f$ as $\mathbb Q(\lambda, \sqrt{-3\lambda^2-8})$.


What is the best way to improve Crazyhouse or Bughouse skills?

Question: I have been playing Chess variants for a while now, and I would like to know how to improve my skills in bughouse and crazyhouse. Does anyone have any tips or strategies that would apply to either? Any input would be very helpful.
Answer: Since there isn't much material out there to study, the best way is to play with better players.  Of course, studying tactic problems is great for chess and the variants. FICS (free internet chess server) is probably where the best Siamese (bughouse) players are.
It helps if you have some opening systems worked out (since in Siamese being ahead on the clock can be crucial).
Published tips are here: http://www.freechess.org/Help/HelpFiles/bughouse_strat.html
https://www.chess.com/blog/Sorsi/advanced-bughouse-tips
Answer: Bughouse is a very tactical game and you can practise bughouse tactics by doing puzzles on this website: https://bughouse.ca/
It should also help for crazyhouse.
(disclaimer: I'm one of the developpers of this website)


What division colors were worn at individual bridge stations during the Star Trek TOS movie era?

Question: I'm working on a story set in the TOS movie era (post-Wrath of Khan) and I need help understanding who would have worn what division color on the bridge of the Starship. I've linked two bridge layouts below (a Connie variant and an Excelsior) with the crew positions labeled. My biggest problem is figuring out Tactical wore and who besides the Captain wears Command white. Any help on this would be great!
Answer: Due to the time period, we're talking about the maroon uniforms. Immediately post Wrath of Khan is still early enough that they haven't abandoned the undershirts - the uniform seen on the crew of the Bozeman (circa 2278) appears to be complete, while later uniforms seen on the crew of the Enterprise-C (circa 2344) and on Jack Crusher (circa 2349) omit the undershirt.
As you've already mentioned, a 2270 era captain is the only person who regularly wears white aboard ship. According to Memory Alpha, other than medical sciences (green), cadets (red), and helm or engineering officers (explicitly separated from the other operations staff with gold), everybody else wears grey.
Constitution Class
On the Constitution class, you have:

White - Commanding Officer (15)
Gold - Engineering (3), Propulsion (4), Damage Control (5), Helm (14)
Grey -  Communications (2), Auxiliary Systems (8), Defense Systems (9), Weapons Systems (10), Tactical (11), Science (12), Navigation (13)

I've deliberately skipped Environment (6) - it is equally plausible for such a station to be occupied by an engineer, scientist, or even medical sciences crew.
I've flagged the combat related positions as grey as well, because they're clearly none of the others. Anecdotally primarily due to the change in uniform, Chekov was the weapons officer during the first film, and wore grey in all the other films.
The dedication plaque (0), master systems display (1), main viewscreen (7), space suit locker (16), and airlock control (17) would look pretty silly in uniform. The upholstery and carpet involved can vary, though.
Excelsior Class
Helm is renamed Conn (short for flight control), so the only truly new element is "Mission Ops". A little further in the future, but TNG Technical Manual hangs mission ops on the first word, mission. What kind of officer would occupy the station depends on the currently active mission - sometimes, it isn't occupied at all.
Comment: Thanks T.J.L. I had actually completely forgotten all about posting this question until last night. I'd already settled on roughly the same setup as you commented. As far as Environment, Mission Ops, and Ops Management go on the Excelsior (the main ship for my story's captain; he was Chief Tactical and then First Officer on the Connie), I selected gold for Enviro (I liked having a full "Engineering Quarter" on the bridge), and grey for the assorted Ops stations. For the Aux stations I imagine they'd be kept empty with any division(s) taking over the consoles depending on the current needs.
Answer: Wrath of Khan took place around 2285. You can consult memory alpha for more uniform details than you'll probably know what to do with.
https://memory-alpha.fandom.com/wiki/Starfleet_uniform_(late_2270s-2350s)
Comment: Hi OrangeDog. I know it's based on division, hence my initial question being what division colors. It's easier in TNG and TOS, since there were only three colors overall. Looking at the Excel bridge picture, I'd assume only the Captain wears Command white. Helm, Engineering, and Propulsion would wear Ops ochre at the time; Science, Comms, and Nav would wear Ops grey. What I'm curious about is the Mission Ops officers and tactical, if they would wear grey or ochre based on the TWOK division colors, and who else would wear Command white (if anyone).
Comment: Hello Adam, welcome to [scifi.se]. How about a summary of what can be found at the other end of your link? We prefer our answers to be self-contained. Have you taken the [tour] yet?
Comment: Thanks. Memory Alpha was the first place I looked, but there's still no indication of what a Tactical Officer wore at the time, since as far as I know there was no dedicated Tac Officer onscreen until Tasha and Worf took the role in TNG (regardless of every Movie-era bridge I've seen having a dedicated Tac station). Sulu and Chekov both had the ability to fire weapons, but Sulu wore Ops Yellow and Chekov wore Ops Grey, and neither was a dedicated Tac to begin with. Hence my confusion.
Comment: The uniform depends on division, not bridge post. The tac officer wears whatever colour belongs to their division. Presumably every bridge officer could be command division, but there's a greater chance of e.g. tac being security, comm being science, helm being engineering, etc.


A clarification of nonexistence

Question: This is similar to a question I asked long ago, but there was a misinterpretation. People often say that, for instance, unicorns don't exist, but isn't it more correct to say that there are no unicorns? The first statement ascribes the property of nonexistence to unicorns, which is incorrect, because there are no unicorns in the first place. So, then, why do people continue to make this blunder? This question is slightly different than the previous one because I am not asking if talk of nonexistent objects is a language game.
Answer: Imprecise language is getting in the way
You interpret the meaning of "Unicorns don't exist" as "there's this thing called a unicorn which has the property of not existing" which you have properly identified as being incorrect. However, consider this interpretation: "Unicorns don't exist" meaning "The set of all unicorns has no elements", or alternatively "There does not exist an element in the set of all unicorns". Either of these would be equivalent in meaning to your suggested "There are no unicorns" as the definition of "are" in this case means "to exist". I believe this is a case of shorthand being misinterpreted contrary to meaning.
Comment: Alternatively: There does not exist something with the property of being a unicorn. Or: All things that exist have the property of not being a unicorn.

A clarification of nonexistence


What is the evidence for virgin conception?

Question: What is the quality of evidence to support virgin conception when sperm is either deposited on the vulva without penetration, or on clothing adjacent to the vulva.
Answer: At least one study reported that a number of women self reported outer-course resulting in conception from a survey of 7870 respondents:

Results 45 women (0.5%) reported at least one virgin pregnancy unrelated to the use of assisted reproductive technology. Although it was rare for dates of sexual initiation and pregnancy consistent with virgin pregnancy to be reported, it was more common among women who signed chastity pledges or whose parents indicated lower levels of communication with their children about sex and birth control.

The study attempted to make it clear as to what the differences between outer-course and inter-course were but it's possible a number of the respondents still answered incorrectly.  So we still have to accept that these are unconfirmed reports.
At present there is no controlled experimental evidence to confirm that this can happen, and biologically, it seems highly implausible that this actually does happen.  Male fertility is reduced when sperm counts drop below 20 million sperm per ml, and this is when the sperm is introduced into the vagina.  A normal ejaculate contains 200 million to a billion sperm.  From these only a few reach the egg and then more then one is required to breach the corona radiata to allow a single sperm to fertilise the egg.  However, pregnancy can occur even when coitus interruptus is practiced since the pre-ejaculate may contain sperm.  So, this suggests that much lower numbers of sperm in the vagina then normally considered necessary can still result in pregnancy.
At present there is no experimental data on the passage of sperm through clothing though one would assume it's possible.
So, in summary, the evidence has not independently verified that outer-course can result in pregnancy, and is an area that requires further investigation.


What is the difference between IMUs and other devices that have accelerometers and gyroscopes (smartphones, tablets, sensewear etc.)?

Question: The general definition of IMU says that any device that has accelerometer, gyroscope and magnetometer/GPS packed together is an IMU. Then why aren't other devices that have the same sensors called IMUs?
Comment: IMUs have built in math processors for absolute orientation.
Comment: Could you please help me understand what you mean by absolute orientation ?
Comment: @user6446313 That would be orientation relative to North Pole or any other well-defined origin
Answer:
The general definition of IMU says that any device that has accelerometer, gyroscope and magnetometer/GPS packed together is an IMU.

Where did you find that definition?
It's true that most systems classified as IMUs have most of those sensors, but there are variations.
In general, an IMU is a device designed to track the position and orientation of an object — along with their derivatives such as velocity and angular rates.
The data is provided relative to some reference. If the reference is an absolute one, such as the orientation of the Earth, it is referred to as an absolute IMU. Otherwise, if the the reference is arbitrary (such as the position/orientation at power-up), then it is a relative IMU.
Accelerometers and rate gyros give relative information only, and are subject to drift in various forms. An IMU that includes only these sensors can only be a relative IMU. Magnetometers provide zero-drift readings of orientation, while GPS can give a zero-drift measurement of position. IMUs that include these sensors can provide absolute data.
It takes a significant amount of software to take the raw data from all of the available sensors and "fuse" it together to come up with the best possible estimate of position and orientation. The Kalman Filter is one popular approach.

Then why aren't other devices that have the same sensors called IMUs?

Because "being an IMU" is not their primary function. They may not even include the appropriate software to combine the data from the various sensors into a full position+orientation solution.
Comment: Thank you @Dave Tweed for your response.  By 'general definition' I meant the general usage of the term IMU, which I read on the Wikipedia page. Your explanation clarifies things for me very well. Thanks !
Comment: I disagree a hair with your IMU definition.  An IMU must track orientation and position, and it must use INERTIA do do so.  Video-based systems, for example, are not IMU's


Shell script to check if something is plugged in the wifi USB port

Question: I have a wifi access point that allows to plug a USB hard drive accessible from any computer sharing the same wifi. I would like to know if there was a way a shell script could test if something is plugged there or not.
If there is a way to check which USB key or hard drive is plugged would be a delight, but I'm not asking that much.

edit
The goal is to check if the drive is on before I can work with the files. I want to access the drive using samba. The IP is 192.168.0.1. I can get the name of the drive, but the IP is fix, whichever drive I plug.
NOTE: my final goal is to upload files on that drive with a shell script. I don't mind if you give me another way to do it: SSH, FTP, HTTP, morse code, …
Comment: How do you access the drive? Samba? http?
Comment: samba, I'm adding details to the question.
Comment: Add some more details. How is the share called? Do you access it over a specific IP? Hostname? Is the name of the share constant, or do  you have to browse your Windows network? etc. etc.
Answer: You're probably not going to be able to figure out which drive it is without some fiddling around.  More on that later.
Firstly, try to mount the device.  If the mount fails, nothing is plugged in.  Change the paths and options, obviously.  (must be run as root, or with sudo)
mount -t cifs -o <options here> //192.168.0.1/share_name /mnt/whatever
if [[ $? = 1 ]]; then
   echo "Drive not available."
   exit 1;
fi

If it succeeds, continue on with your copies to /mnt/whatever.
If you want to be able to tell which drive is inserted, one simple thing you could do is create a file in the root of the USB key or drive that identifies it.  I have a Corsair USB key, for example, create an empty file called "CORSAIR" in the top directory of the key.  Obviously, you could call it anything you want.  Then, after mounting, test for the existence of the file.  You could even unmount it at that point and mount it on another directory for further use.
if [[ -f /mnt/whatever/CORSAIR ]]; then
    echo "CORSAIR USB key detected.."
    # do some stuff
fi
if [[ -f /mnt/whatever/PERSONAL ]]; then
    echo "Personal USB key detected..."
    umount /mnt/whatever
    mount -t cifs -o <options> //192.168.0.1/share_name /mnt/PERSONAL
fi

Since you're mounting and unmounting, you'll have to run as root or use "sudo mount", which will prompt for passwords.


Who launched nuclear weapons first?

Question: Is there sufficient information in the Fallout universe to infer who launched Nukes first?
Comment: han shot first!
Answer: From Fallout Wikia:

It is not known who launched the first nuclear weapon that started the conflict. President Richardson would tell the Chosen One that China launched first; however, it is not known if he was telling the truth. Captain Zao was in the vicinity of Boston at the time of the Great War. However, possible Chinese bombers were spotted off the Bering Straits of Alaska at least as early as 3:37am Eastern Time. Enemy nuclear missile launches were confirmed by NORAD at 9:13am, with U.S. bombers scrambled and airborne at 9:17am. Nuclear missile strikes on New York and Pennsylvania were confirmed at 9:42am, with nuclear strikes on Boston and Washington occurring at 9:47am; this information and multiple reports of U.S military forces advancing across the Chinese mainland and occupying Shanghai and Nanjing makes it likely that the Chinese were the first to initiate a nuclear strike.

Source
Comment: I've cut the quote down to the relevant part, and bolded the last line for emphasis. Feel free to add or subtract from this if you wish

Who launched nuclear weapons first?


Plugin: how to get all the types available in my eclipse Workspace?

Question: I'm writing an eclipse plugin, and I want to get all the types that are available in my workspace,
like when pressing Ctrl+Shift+T,
but in a list or array.
How can I do it?
Answer: The relevant code is referenced from the org.eclipse.jdt.internal.ui.dialogs.FilteredTypesSelectionDialog (which the OpenTypeSelectionDialog triggered by ctrl-shift-T inherits from).
If you inspect the fillContentProvider() method you'll see it the org.eclipse.jdt.core.search.SearchEngine, which is passed a TypeSearchRequestor and TypeItemsFilter to match the required types.
If you look at the Javadoc for SearchEngine.searchAllTypeNames() and/or debug its execution, you should have a pretty clear idea how to obtain the workspace types into a requestor, and process them accordingly.
Comment: I was searching the same thing;) PluginSpy helps :) +1


MySQL VARCHAR storing after setting null

Question: I have big MySQL InnoDB table with some varchar(512) column. Next inserted rows depends on previously inserted. After inserting new row, varchar field of previously inserted row will be state meaningless. Previously inserted rows always were marked as 'processed' (by performing update query) but varchar field not erased. This field not indexed. Should I set value of that fields in previously rows to null (by memory saving reasons)?
Answer: VARCHAR can't be 512! The max for varchar is 255. So for larger amounts of data use TEXT or MEDIUMTEXT.


Is goodwill necessary in order to make progress on the Path?

Question: It seems impossible to have goodwill in certain situations. Is it enough to be tolerant and forgiving of other's faults?
Comment: right intention is part the 8-fold path. compassion is well known to be the motivator in bodhisattva progress. HTH :-)
Comment: if you mean consummation, rather than progress: arhats lack certain "emotions", I believe (that is one way for us to think about the defilements), whereas bodhisattvas would, I suppose, be aware they are transient and empty. all the best!
Answer: I found this essay on goodwill helpful, particularly the excerpt below:

"... you wish not only that beings be happy, but also that they avoid
the actions that would lead to bad karma, to their own unhappiness.
You realize that happiness has to depend on action: For people to find
true happiness, they have to understand the causes for happiness and
act on them. They also have to understand that true happiness is
harmless. If it depends on something that harms others, it's not going
to last. Those who are harmed are sure to do what they can to destroy
that happiness. And then there's the plain quality of sympathy: If you
see someone suffering, it's painful. If you have any sensitivity at
all, it's hard to feel happy when you know that your happiness is
causing suffering for others.
So again, when you express goodwill, you're not saying that you're
going to be there for them all the time. You're hoping that all beings
will wise up about how to find happiness and be there for themselves."
Answer: Surely it's nearly impossible for one not familar to the Dhamma of the Sublime Buddha, good householder. Maybe good to start to investigate it via metta here and especially the essays. For intensive and benefical, good to leave home and commercial places first.


Enable Request File link in SharePoint Site using Set-SPOSite -RequestFilesLinkEnabled

Question: The documentation for Set-SPOSite has the argument for RequestFilesLinkEnabled and it can be passed without returning an error but does not provide the RequestFilesLink option on the Sharepoint site. I have enabled "anyone links" for the site I'm testing this on. Is the configuration option left for when this feature was briefly introduced but removed a few years ago?
I can use the Request File feature in OneDrive for business but I would prefer the landing page not show the account owner's name above the title that you provide. Does anyone have a workaround for removing the account owner display name?
Answer: It appears that while the Set-SPOSite has an argument for RequestFilesLinkEnabled it a feature that is only available in OneDrive for Business and not available in SharePoint Document libraries.


How to set up Https on cPanel

Question: Hello
I want to set up https on CPanel!
 but I don't know how?

Is there anyone here that can help me?
My cpanel version is cPanel Pro 1.0 (RC1).
Comment: Do you want to access your cPanel over https, or make it so that all or part of your site is accessible over https?
Comment: i done this.
now tell me what settings to be done to open only https version of site, even if user enter xyz.com - it should open https://xyz.com.
Comment: If you search this site you can find the answer to your question, e.g. webmasters.stackexchange.com/questions/16048/switch-to-https. I removed your email address from your answer (now a comment) as if someone emails the answer to you then no-one else can find out how to do it
Answer: Step-by-step instructions
make sure you have download the appropriate files for your certificate before beginning

Open the WebHost Manager and click Activate your SSL Certificate in the SSL/TLS menu.
You will see a screen with three boxes on it. Your issued certificate, RSA private key and certificate bundle must be pasted into boxes 1, 2, and 3, respectively.

In the first box, paste in the contents of your issued SSL certificate. If the certificate file is on your server, you may use the Fetch button to copy it from the file.

In the second box, paste in your private key which was generated when you created the CSR.

In the third box, paste in the certificate bundle (gd_bundle.crt).
At the top of the page click Do it.

How to set up Https on cPanel


Why gravitational waves are not produced by objects moving at constant velocity?

Question: Gravitational wave is produced by change in gravitational field, source. If something is moving away from me at constant speed, its gravitational field will vary. But why only accelerating bodies produce GW?
Comment: This is a fact that holds true not just for gravitation, but also for other classical fields (like the electromagnetic field): You need acceleration for radiation to be produced.
Comment: Constant motion can be turned into stationary object by an appropriate frame change.
Answer: Because radiation from such a body undergoing inertial motion would gainsay Galileo's postulate of relativity, i.e. that there is no measurement one can make within an inertial frame that could detect that frame's motion relative to another inertial frame. Gravitational radiation would bear energy away from the body, and in principle (at least from the classical paradigm that holds in special and general relativity) this energy loss could be measured from within the frame.
If you think about it, the proposition that bodies emit radiation when in uniform motion relative to your own inertial frame is a tacit assumption that your own frame is privileged.
If you are looking for an answer with more "technology" applied, then, as user Danu comments, the lack of radiation from uniformly moving bodies is not special to gravitation: there is an approximation to GR called Gravitoelectromagnetism which is almost  exactly like Maxwellian electrodynamics and can be derived from assuming a delay, propagating at speed $c$, in gravitational effects. It's kind of like Coulomb's electrostatic law modified to heed the locality requirements of special relativity. In this picture, the gravitational field lines of a moving body are distorted in a relatively uniformly moving frame, but their shape does not change and the whole solution (essential like that described the Liénard-Weichert Potential for zero acceleration) is a field of constant shape translating uniformly with the body. One can easily see from this picture that only accelerating bodies can radiate energy: a field of constant shape whose only change is uniform, rigid translation with the body producing it must have a constant energy and there can be no radiation.
One should be warned, however, that the gravitoelectromagentic approach grossly overestimates gravitational radiation power radiated from accelerating bodies by using the analogue of Larmor's formula / Liénard-Weichert Potential. Such an approach gives several gigawatts radiation from the Earth, whereas full GR calculates around about 200W. (Incidentally, the several gigawatt figure is also too small to measure for something Earth-sized).
Answer: Gravitational wave is a concept predicted by General Relativity by Albert Einstein. The very first point to look is that how a theory extended from explaining the symmetry of physical laws in inertial frames to include accelerated frames become a theory of gravitation. This is the starting point of General Relativity. It's known as equivalence principle. It says that gravity is an acceleration effect that determines the geometry of spacetime. You cannot distinguish, if put in a sealed container, that if you are in some gravitational field or whether the container is accelerating upwards. You cannot distinguish your inertial mass and gravitational mass.
So, with the aid of this, Einstein said that what massive substances can do on spacetime, the accelerating bodies can also do. Gravitational waves are the gravitational potential energy radiated by a changing gravitational field source. As we say that electromagnetic fields can be produced by charges moving at uniform velocity, electromagnetic radiation requires the charge to accelerate, same is for gravitational waves. A gravitational field can be created by mass and energy distribution. But, to cause ripples in spacetime, the field should be fluctuated rapidly (think of the ripples you can make on water). As a simple case, the massive object should vibrate. This means, the body is accelerating.
So to see any effect of gravity, you must see an acceleration. Then what's so special about GW?
Comment: very clear answer . What's so special : weakness. Now, each theory may claim 100-year wait before declaring it irrelevant
Answer: I think the other answers are sufficient, but I would like to leave my two cents just to clarify a few possible concerns.
I can see you imagining that moving objects in your reference frame leave a gravitational "wake", like a boat moving in water, but gravity and relativity don't quite work this way.
To grossly simplify, from the moving object's perspective, you are the one moving and it staying still. However, from your perspective, your gravity is equal in all directions, and from the object's perspective, so is its gravity.
Now, gravitational waves come from acceleration. If there is no acceleration, there are no gravitational waves.
"But when the object passes me, doesn't its gravitational 'wake' cause me to accelerate?" If you have mass, the answer is yes, but because you have mass, your gravity also affects the object and causes it to accelerate. In this case, yes gravitational waves are generated, but only because you and the object interacted and caused acceleration.
If you were, however, a massless/energy-less/basically-non-existant observer, then the gravity would do nothing to you, and you would have no affect on the object. There would be no acceleration, and therefore, no gravitational waves would be generated.
I hope that makes sense.
Answer: Wave is an oscillation, while a source just emit a constant field (in its frame). To have an oscillating field, you need an oscillating source. A sudden linear acceleration or deceleration would also transmit a "bump".


Why does temperature remain constant during phase changes?

Question: In a phase change the temperature remains constant but I can't understand why. The answers I have read state that during phase changes energy is only used to break bonds between molecules rather than increasing kinetic energy. However why is this the case? Why couldn't the supplied energy be used solely to increase the kinetic energy of particles?
Comment: If you need to overcome potential energy barrier to reach a different state, it is obvious that all energy cannot be used to increase kinetic energy when that state is reached. Like at ionization of atoms or at escaping gravity of a star or a planet.
Comment: "Temperature" is essentially movement of molecules.  So you are on the right track thinking kinetic energy.  Phase change is an energy sink moving from solid, to liquid to gas, so more energy **input** is required.  In other words, temperature cannot rise because the molecules cannot move faster (increase KE) until phase change is completed.
Comment: There are other phase changes like iron going from ferrite ( body centered cubic) to austenite ( face centered cubic). Thermocouples in a commercial heat-treat furnace would show a temperature drop while heating a load of steel as the phase change absorbed heat. Impressive to witness.
Answer: It's easier to see in a specific example, e.g., boiling water. At 100°C and 1 atmosphere pressure, as more heat energy is added, the pressure of the water at the spot where heat is applied exceeds the pressure pushing on it, and bubbles form and rapidly expand, pulling away that added energy. The water vapor above the boiling water can be hotter than 100°C,  but the liquid cannot... except for superheating.
Your presumption is not wrong: fairly clean water, without air bubbles, can be superheated well above 100°C, if left undisturbed -- a metastable state. The slightest disturbance, such as vibration, can cause the water to suddenly boil violently, "exploding" from the container. The remaining water is now below 100°C.
A similar phenomena is supercooling of water, in which heat energy has been transferred out of the system, yet the water does not freeze until it's disturbed (or is sufficiently cold, about −48 °C, below the freezing point of mercury). If you want to repeat the supercooling demonstration (much safer than superheating!), use a clean, smooth, plastic container  and water that is clean, and has air bubbles removed by first boiling and allowing it to cool in a container with a lid (to keep out dust) before pouring it into the bottle.
However, those answers were also correct... once equilibrium has been reached. Eventually, superheated water will flash to steam. Supercooled water will eventually freeze. And even glass can crystallize. Don't let this dichotomy faze you, though.
Answer: This is one of the over simplifications that no one thinks about after being told. For a one component system the phase rule, F = C-P+2, states for two phases in equilibrium there is one degree of freedom. When evaporating a liquid, maintaining a constant P[vapor pressure] fixes the temperature of evaporation. A variation in P causes a variation in Temperature. The effects in melting are the same. To maintain a constant steady state Pressure an external energy source is required. If the energy source is the phase itself [or the heat source is insufficient] the temperature will change until equilibrium is reached; then the constant pressure means an invariant temperature.
In normal boiling, exposed to the atmosphere when the vapor pressure reaches atmospheric pressure P cannot increase since increasing evaporation simply pushes back the atmosphere. The Vapor pressure becomes constant and the temperature becomes constant. This is assuming sufficient energy input and not excessive heating and reasonable mixing and good exposure to the atmosphere.
Comment: So you can cause a phase change through compression or expansion, during which the system will stay on the coexistence line. But what do you mean by this: "then the constant pressure means an invariant temperature" ?
Comment: Just that! when the vapor pressure equals the constant atmospheric pressure the last freedom is removed and the temperature is constant.
Comment: If the vapor pressure is changed adiabatically the vapor will condense or liquid evaporate absorbing or releasing the heat of vaporization and the equilibrium point will change temperature. If the heat is supplied or removed externally the amount of the phases will change and P will remain constant.


The speed of JIT compiling method call compared to reflection in .NET

Question: Reflection is usually said to be slow. However, when .NET JIT compiler needs to compile a call to a method it needs to refer to the same module metadata tables (if I understand it correctly). Does method (and field) lookup incur the same perf. hit in JIT compilation and in reflection?
Answer: I think the two might be comparable, but don't forget that JITting is a one-time cost, while using reflection isn't.


Does sodium borohydride reduces alkyne?

Question: Will an isolated Alkyne or an alkene be reduced using sodium borohydride ($\ce{NaBH4}$)?
Comment: While Nilay's answer is interesting, sodium borohydride itself won't reduce isolated bonds like these. I'm even kinda surprised you'd ask.
Answer: Why not?

Alkenes and alkynes are rapidly reduced to the corresponding alkanes using sodium borohydride and acetic acid in the presence of a small amount of palladium catalyst. The heterogeneous reaction is conducted in open air at room temperature. Reactions typically afford conversions to the alkane product of 98% or more within 15 min. The best solvent system was determined to be isopropyl alcohol, though reduction also takes place in solvents such as tetrahydrofuran, chloroform and, with some substrates, even in water. The method described is a convenient alternative to hydrogenations that require an external supply of hydrogen gas.

Ref.: Anthony T. Tran, Vincent A. Huynh, Emily M. Friz, Sara K. Whitney, David B. Cordes, A general method for the rapid reduction of alkenes and alkynes using sodium borohydride, acetic acid, and palladium, Tetrahedron Letters, Volume 50, Issue 16, 2009, DOI: 2009,10.1016/j.tetlet.2009.02.014.
Comment: Note - no reaction will occur without the Pd catalyst
Comment: @Waylander that was my real question...if only NaBH4 was used...thanks:)
Comment: Isn't this more of a reduction with hydrogen produced in situ?

Does sodium borohydride reduces alkyne?


Salesforce: Read email attachments on file upload LWC

Question: I used lightning-file-upload to allow Users to upload files. Now, one of the use cases is, if the file is an email (.msg file type), we need to split the attachments and upload them as individual files.
Tried using a custom file upload component, but could not get a way to read the attachments.
Any ideas around how this can be achieved.
Answer: You can use lightning-input type="file" to catch these files, and even upload them with lightning-ui-record-api via the createRecord function. To understand how to read a .msg file, you'll need Microsoft's [MS-OXMSG]: Outlook Item (.msg) File Format specification. You can use something like MSG Reader to read the contents of the file (note: I have not reviewed this software, you may need a different once). This is the core of everything you need, but some assembly is required.


Ran 2 cycle without mixed gas :(

Question: So I just purchased my first outboard boat motor. It's a 9.9hp 1997 Mercury. I should have known better but didn't realize I needed to run 2 cycle gas. So I ran it for about 15-20 minutes total. Mostly at a medium-low idle speed. I revved the engine a couple times during this process. It ran fine throughout and it didn't stall/seize.  Well, my neighbor stopped by and we were talking and I realized my error. So my plan at this point is this... drain the present non-mixed gas and fill with proper mix. I also purchased a valve pressure test tool to see if I've lost pressure. Any other recommendations?  Thanks!
Comment: Welcome to Motor Vehicle Maintenance & Repair!
Comment: Engines that size are supposed to run double oil (break in mix) for so many hours before switching to its recommended oil ratio, consult the owners manual for instructions
Answer: I think you're doing what you need to do. You won't really know (and I cannot tell you) how much damage you've done ... I'd suggest at this point, your engine is good and broke in! The fact you didn't rev it too much is a good thing. As for going forward, you should put the 2-cycle mix in it and let it idle on that for a while without revving it at all. This is to get the oil into the engine and let it do it's thing. Once it has idled for a good five minutes, I'd think that's about the best you're going to be able to do. Then run it like you stole it.

Ran 2 cycle without mixed gas :(


Why AC induction motor is used for high power applications?

Question: I know that in the variable voltage variable frequency you are able to keep the torque constant in various speeds , but i have also read something about them not requiring commutators but i couldn't really understand this part , can someone explain or provide me with some useful sources . thanks
Comment: @mkeith I know what you meant **BUT** "no electrical connection" might be better put as "no electromechanical connection" or even "no mechanical connection" as there is indeed very much an "electrical" one in the form of the magnetic field that the power is transferred through (as I know you know).
Comment: There are some applications where the AC motor can simply be connected to the mains power directly and run at its rated capacity continuously for years. No other motor can do that. Induction motors do not use commutation(switching). The stator is energized with AC power. This causes a rotating magnetic field which energizes the rotor by induction. The rotor tries to keep up with the rotating field. There is no electrical connection between rotor and stator.
Comment: @RussellMcMahon, noted. But can't edit the comment.
Comment: @mkeith If you care: copy comment to editor -> delete comment -> repost edited comment -> ping RusselMcMahon so that he deletes his now obsolete comment. In this way we can keep comments clean.
Answer: DC motors require commutators. All of the mechanical output power must be transferred to the rotor through the commutator. The maximum voltage and current for which a commutator can be designed limits the maximum power for which DC motors can be designed. AC motors don't have that limitation, so they are used at power levels that DC motors are either impossible to design or very difficult to build.
Even at power levels for which DC motors have commonly been used in the past, the commutator poses a maintenance and reliability problem. As economically competitive variable frequency induction motor drives have matched and exceeded the performance and reliability of DC motors and controllers, they have become the preferred alternative for most uses.
Above some power level, wound-rotor synchronous motors are used rather than induction motors. That may have to do with some design issue, efficiency, manufacturing cost or some combination of factors.
Product line descriptions of various manufacturers indicate that induction motors are available with ratings up to at least 10,000 horsepower (7.5 MW). Wound-rotor synchronous motors are available with ratings up to 135,000 Hp (100 MW). Synchronous generators are available with ratings up to at least 2000 MW. Synchronous generators have been operated up to 380 MW as motors in a pumped storage hydroelectric plant.
Comment: I guess real engineers design stuff like that. I am feeling kind of puny at the moment.
Answer: Your question is different than what the subject line says.
There is a truly vast amount on web re the how and why of AC induction motors.
See references below, but:
The induction motor was invented by Nikola Tesla - so it obviously uses magic as part of its operating principle. The magic Niccolai discovered here is probably his most useful invention.
A 3 phase induction motor is effectively a combination of a rotating transformer plus an application of magnet to magnet attraction and repulsion.
The stator of a 3pIM consists of 3 sets of coils that produce a rotating magnetic field at AC mains frequency.
The rotor of the motor consists of a series of windings in the form of conducting "bars" which act as the secondary of a transformer in conjunction with the stator windings. When the rotor spins the effective frequency "seen" by the rotor windings is the difference between the rotating field frequency (usually 50 Hz or 60 Hz depending on country) and the rotational frequency of the rotor. If the rotor frequency equalled the mains frequency there would be 0 frequency difference so no transformer action. As the rotor lags behind the stator field frequency the difference frequency induces currents in the rotor bars and produces magnetic fields.
The motor is designed such that the induced rotor magnetic fields serve to attract the rotor magneic poles towards the rotating magnetic field poles causing the induced currents, so the rotor chases" the field causing its currents. If there is minimal loading on the rotor then it will spin close to mains frequency. As the rotor is loaded it is "pulled away from" the rotating fields, causing the "slip" frequency to rise, causing more current to be induced, causing the available powerto increase, causing the rotor t pull back towards lock, causing the slip frequency to decrease, causing .... !.
So that a stable point is reached where the rotor trails the rotating field by a sli frequency which allows the power to be transferred to cause stable operation.
Look at this specific, detailed and very well illustrated tutorial followed if then needed by a slow and careful reading of this section on this page and a look at the animated diagram, plus a look at these many images each linked to a web page , and if still needed as many of these videos as you can tolerate and these as requisite should make you a world expert, if desired.
________________________
To answer your subject line question:

Why are AC induction motors used for high power applications?

High power AC induction motors are almost invariably 3 phase powered motors. Low power motors may be single phase operated due to the mote common use of songle phase feeds in domestic and small commercial and small industrial use, but for power above a kilowatt or few 3 phase motors are the norm.
3 phase AC induction motors tend to have the best overall cost-benefit ratio of any motor type available in many applications. While in some specific applications other types may be more suitable the 3 phase AC induction motors  features of

No commutator or brushes
No permanent magnets
ONE moving part (plus bearings)
Speed defined by frequency of power supply (less a small amount),
Relatively simple construction
Good power density
Relatively available and low cost materials (copper or aluminium for windings, steel for laminations, + housing material (steel or cast iron usually).
Low cost compared with many alternatives

and a few more factors, make it 'hard to beat' in many cases.


is there a way i can control which parts of the render have the glow?

Question: im trying to replicate something similar to below where near the exhaust the flames are extremely bright and towards the end of the flame it fades out. i got the glow to be amped up but i have no idea how i can go about controlling where the glow is coming from.
Answer: Use the threshold value.
Pixels that are brighter than the threshold will get the glow.
Values lower than those set by the threshold will not be affected.
Read: Any way to control light halos in the compositor based on emission level?


8051 Move Data To/From External Memor

Question: As I was using this instruction movx a,@dptr . and I didnt udnerstand how a 16 bits number is being copied to the accumulator when the accumulator can only hold 8 bits ?
Comment: That is not happening. A single 8-bit word is copied into `A`. But the address `dptr` might be a 16bit address.
Answer: movx a,  @dptr copies 8 bit data byte from external memory location addressed by 16 bit number stored in dptr (obviously,  if it is properly interfaced).
For e.g. if you want to copy byte (i.e. 8 bit)  data stored at 1500h in your external memory.  You'd write :
mov dptr,  #1500h
movx a,  @dptr
Also, keep in mind that dptr (data pointer register)  is actuality combination of two 8-bit special function registers,  dph and dpl (having addresses 83h and 82h,  in internal RAM  respectively).
You might want to re-read atleast all indirect addressing mode instructions.

8051 Move Data To/From External Memor


set cache in QtWebKit

Question: So I wrote this class overriding the base QWebPage.
This is with Qt4.8.5. I cannot really upgrade to a more recent version for all kind of reasons... Anyway the caching classes have been introduced in 4.4 so I should be fine.
This is written based on the following doc: https://web.archive.org/web/20140129011151/http://blog.qt.digia.com/blog/2011/04/29/http-caching-with-qt/
MyQWebPage::MyQWebPage(QObject* parent /*= nullptr*/) : QWebPage(parent)
{
    QWebHistory *history = this->history();
    history->setMaximumItemCount(0);

    QNetworkAccessManager * pNAM = networkAccessManager();
    if (pNAM) {
        QNetworkDiskCache * pNDC = new QNetworkDiskCache(parent);
        pNDC->setCacheDirectory( QDir::homePath() + "/AppData/Roaming/Autodesk/ash_web_cache" );

        qint64 size = pNDC->cacheSize();
        printf( "cache size = %ld\n", size );

        size = pNDC->maximumCacheSize();
        printf( "maximum cache size = %ld\n", size );

        const qint64 desired = 1024*1024*1024;

        if (size < desired) {
            pNDC->setMaximumCacheSize(desired);
            size = pNDC->maximumCacheSize();
            printf( "new maximum cache size = %ld\n", size );
        }

        QString dir = pNDC->cacheDirectory();
        printf( "cache directory = %s\n", (const char*)dir.toUtf8() );

        pNAM->setCache(pNDC);
    }
}

I am giving 1GB of cache for now just to make sure that what I'm doing should be cached properly.
So I have my webapp showing up, I open the inspector, I go in the network tab.
My web page shows a bunch of thumbnail images.
When I reload my page I dont see much caching taking place although there should be plenty of space available !
If I do the same thing in chrome all my thumbnails get a 200-OK-fromcache, as expected!
So there is no problem with the date, etag etc since it's all working in chrome.
But in this qt web app, no, not even a 304...  Everything is a 200 no cache at all.
The printf lines in the code above will print:
cache size = 8342691

maximum cache size = 52428800

new maximum cache size = 1073741824

The cache size of 8342691 is exactly the size of the directory I had set in setCacheDirectory (precisely, one of its subdirectories called data7)...
But I cant find my thumbnails in there.
Is there anything I am doing wrong?
BTW I noticed this function here in QtWebSettings:
void QWebSettings::setObjectCacheCapacities(int cacheMinDeadCapacity, int cacheMaxDead, int totalCapacity) [static]

I haven't tested this yet...
There is also this cache control that I could tweak:
enum QNetworkRequest::CacheLoadControl
Controls the caching mechanism of QNetworkAccessManager.
QNetworkRequest::AlwaysNetwork  0   always load from network and do not check if the cache has a valid entry (similar to the "Reload" feature in browsers); in addition, force intermediate caches to re-validate.
QNetworkRequest::PreferNetwork  1   default value; load from the network if the cached entry is older than the network entry. This will never return stale data from the cache, but revalidate resources that have become stale.
QNetworkRequest::PreferCache    2   load from cache if available, otherwise load from network. Note that this can return possibly stale (but not expired) items from cache.
QNetworkRequest::AlwaysCache    3   only load from cache, indicating error if the item was not cached (i.e., off-line mode)

But the default AlwaysNetwork should be fine so I don't think I need to change this.
Answer: I encountered same problem. It is a bug of document but not code logic.
Please add this line into your code.  setNetworkAccessManager(pNAM);
MyQWebPage::MyQWebPage(QObject* parent /*= nullptr*/) : QWebPage(parent)
{
QWebHistory *history = this->history();
history->setMaximumItemCount(0);

QNetworkAccessManager * pNAM = networkAccessManager();
if (pNAM) {
    setNetworkAccessManager(pNAM);
    QNetworkDiskCache * pNDC = new QNetworkDiskCache(parent);
    pNDC->setCacheDirectory( QDir::homePath() + "/AppData/Roaming/Autodesk/ash_web_cache" );

    qint64 size = pNDC->cacheSize();
    printf( "cache size = %ld\n", size );

    size = pNDC->maximumCacheSize();
    printf( "maximum cache size = %ld\n", size );

    const qint64 desired = 1024*1024*1024;

    if (size < desired) {
        pNDC->setMaximumCacheSize(desired);
        size = pNDC->maximumCacheSize();
        printf( "new maximum cache size = %ld\n", size );
    }

    QString dir = pNDC->cacheDirectory();
    printf( "cache directory = %s\n", (const char*)dir.toUtf8() );

    pNAM->setCache(pNDC);
}

}
It works for me.

set cache in QtWebKit


Are you able to play LAN with your friends on Minecraft even if they don't have the same mods

Question: For example if you got an x-ray mod if your friends don't have that mod will they be able to join in general to play lan in that world?
Comment: X-ray is a very bad example, since it's considered cheating on most servers.
Comment: You might want to clarify your question, to get more replies.
Answer: Client modifications are optional. If you're using x-ray or other client-side cheats mods your friends don't have to use them. They're completely free to pick their own mods. Even if you don't use x-ray they still could use it (or other mods).
If you want to play on modded server or LAN game requiring certain mods you'll all have to install them. What exactly you need depends on the mod you want to use. Since we don't know what you're up to we can't help you there. The best approach is to read the instructions in the readme file which usually comes with the downloaded archive.
Answer: For servers, it depends on the type of mod. There are 2 types of mods client-side, and server-side, if a mod is client side it can only change the players perception of the world via things like shaders, depth to leaves, or xray. Server side requires both the player and the servers to have the mods, this is for things like build craft, or bibilo craft. As far as I am aware lan works by hosting the world as a local server, and if that is true they should be fine to join without it.
Answer: For most mods, the answer is no. But if you have mods that do not add anything, such as OptiFine, it is fine.


Pink scum on top of brine in crock of sauerkraut

Question: There is a pink scum on top of the brine of my sauerkraut in the crock. What is it & is it harmful?
Bev
Answer: If you're seeing pink scum, it's probably a yeast called Hanseniaspora uvarum. This yeast can make a pink or reddish film on the surface of the sauerkraut during fermentation.
Typically this yeast will grow from one or more of these causes:

Too little salt: while salt is not actually necessary to ferment vegetables, it adds flavor; denatures pectinase (the enzyme that breaks down pectins), keeping the vegetables crisper; and discourages growth of molds and fungi like the yeast you're seeing.

Too much oxygen: yeast is facultative, meaning that it can respirate or ferment (use oxygen or metabolize without oxygen). Fermentation, strictly speaking, is a type of anaerobic metabolism where glucose is broken down into two pyruvate molecules releasing a small amount of energy. If you haven't submerged the vegetables fully in water and/or have the vegetables in an environment where air (containing oxygen) is allowed in, that can cause this yeast to grow. The yeast will also grow in an anaerobic environment, but much more slowly.

If your environment favors the LAB and discourages the yeast, it should not grow.
This yeast is not harmful, so I recommended you carefully take it off the top of your sauerkraut, make sure you have the remaining vegetables submerged, and remove the oxygen from your jar before continuing the ferment.
When you start your ferment there will be oxygen in your jar, and facultative bacteria and yeast will metabolize using it, creating some CO2, which should displace the oxygen if you have a one-way valve. If your jar is sealed the O2 should be used up. After this point your vegetables should only be able to ferment since there is no O2 left. If you open the jar to check on it, you'll once again allow respiration to take place.
LAB likes more a more acidic environment, and the more lactic acid that is created the more your environment will be suitable to its survival, and it will be less hospitable to undesired organisms.
In short, if you set up your ferment properly, you should never have a problem. But if you do see something else growing on top, it's probably safe, but if it's pink and fuzzy that could be a type of mold that produces mycotoxins, so that is not safe to eat.
Answer: This is scum from yeasts in the fermentation. Apparently the sauerkraut is still safe to eat.
This site from Colorado State University on making sauerkraut says:

Ferment:

Place packed container on a tray or plate to catch liquid that may leak fluid leaks out, do NOT pour leaked juice back in, but clean immediately to limit potential contaminants.

Place container in a well—ventilated location (it will have a sour odor) with a relatively constant temperature of 68—72°F, for about 7—14 days. Sauerkraut will ferment faster in warmer temperatures and slower in cooler temperatures.

After bubbling stops (usually about 2—3 days) check that the cabbage is fully submerged under brine. If needed, with clean hands, push cabbage down to draw out more brine. If there is not enough brine to cover the cabbage, stop fermenting at room temperature and refrigerate.

A white or pink yeast scum can appear on the surface at any point in the sauerkraut fermentation process which can be removed and discarded. The sauerkraut below is still edible

 Copyright 2020 Food Smart Colorado. https://foodsmartcolorado.colostate.edu/recipes/preservation/understanding-and-making-sauerkraut/ Site accessed 8 March 2024


How do I force delete a file?

Question: I have a random file placed in my desktop named "Unconfirmed 371801.crdownload" and I am extremely worried it is a virus and I want to remove it immediately but whenever I try to remove it, it throws a report " "Unconfirmed 371801.crdownload" can't be put in the trash. Do you want to delete it immediately? " then when I press Delete it says this "There was an error getting information about "Unconfirmed 371801.crdownload"." and I don't know how to get the information. Any help is appreciated.
Comment: That typically would represent a file being downloaded by google chrome, or another browser.  Are you currently downloading any files?
Comment: A .crdownload file should be invisible to you - the user - so you apparently turned on hidden files. The file contains the information downloaded before it is finished (in other words, once the file finishes downloading its renamed to the correct file name). Chrome cleans these files after a crash or similar corruptions. I advise you to restart (dont open chrome), open the "get info" panel (right click on the .crdownload file), next on the bottom it would have a premissions tab and change the permissions such that you have full access to the file and next you should be able to delete the file.
Answer: Unconfirmed 371801.crdownload is a temporary file that
represents an unfinished download.
In general is not a virus. (unless what were you downloading is a virus)
To delete it you can try to close your browser (if is google-chrome check also that background processes are closed) and try to delete it.
If it doesn't work you can open a terminal pressing ctrl+alt+t.
Now you have to change the directory where the terminal is working with the following command:
cd Desktop

(I'm assuming that your file is placed in your desktop directory and you installed Ubuntu in English international / US).
To delete the file run this command:
rm -f Unconfirmed\ 371801.crdownload

This command will remove the file ignoring any errors. (add \ character because terminal doesn't take into account space in names).
If you want more info about the command you can run from terminal this command:
man rm

If the file is still there you can try to run the rm command as superuser:
sudo rm -f Unconfirmed\ 371801.crdownload

This command will ask you superuser password and after will do the work.
In the end, if the file doesn't disappear, you try to click on your desktop and then press Ctrl+R. This will refresh your desktop.
Comment: When using `rm`, it's better not to start with `-f` unless you're totally sure what's what you want, because *(a)* it can remove files you may not want to remove (such as read-only files) without asking you, and *(b)* it can *not* remove files you do want to remove without telling you it didn't. That's because [part of what `-f` does](http://manpages.ubuntu.com/manpages/xenial/en/man1/rm.1.html) is to "ignore nonexistent files and arguments," so if the filename turned out to be subtly wrong, you'll think you removed the file when really there was no file of that name to remove.
Comment: Thanks to everyone who told me to close chrome (which is what I am using) and do everything else, it really helped! I was worried but you guys helped me. Thanks!
Comment: I have a similar problem with some temp files which are left into the HDD by the PDF reader (Okular), not always, but... Those files have names as ".fuse_hidden0000011d00000003". When I use the rm -f command to try to erase it, the files remain still there, with a new name (a correlative value is added to the last number of the original name). The only one way I found to erase those files, is restarting the whole system. But, I wonder if there is another "more smart" way to do it... Is there???
Answer: I had the same problem and the command sudo rm -f did not work for me. I also could not resume the download. However I was able to get rid of it by deleting everything in the Chrome Menu --> Downloads and then Right Click on the .crdownload file --> Open With --> Other Application... --> Chrome. After this, the file simply disappeared.
Comment: @YufenyuyVeyehDider it can't be posted as a comment due to rights of the poster (not enough cred yet to comment).
Comment: Please, it is preferable to post this as a comment under the answer above because it goes in the same light as @Eliah Kagan's comment.
Answer: Go to the folder where the file is; Right click and open a terminal; Than 'ls' and get the file name.
Than do: sudo rm -rf (filename with extension).
It'll be in your bin then and you can empty the bin.

How do I force delete a file?


Chrome touch ups?

Question: I have several chromed items where small amounts of the chrome has chipped off, leaving bare metal showing.  None of it is in prominent areas, so I just want to touch them up.  I haven't had luck with chrome spray paints in the past, as they never end up looking like chrome.  Is there some paint, marker, or whatever that actually looks like chrome?  I'm not looking for perfection, but passable.
Answer: I ended up going to Michael's, a chain arts & crafts store, hobby store.  While I didnt see chrome, I picked up an Extra Fine Tip Multi-Surface Premium Paint Pen by Craft Smart in metallic silver.  It actually worked very well.  I was able to cover the bare spots, which were very small and hidden.  Unless you were looking for it, you wouldnt spot the touched up areas.  Additionally, the fine tip made it easy to use.  Spray paint would have been a pain.
Comment: FYI, I used this paint pen on a few other bare spots on some chrome items.  I recently was told about some higher quality paint markers that have really good chrome paint, but they are far more expensive.
Answer: Paints have improved quite a bit over the years and quality plays a big role too. This paint provides good results
Krylon K01010A07 Premium Metalic Original Chrome

Chrome touch ups?


Using resize2fs with file system offset

Question: Mount has the option offset to specify that a file system does not start at the beginning of a device but some specific amount of bytes after.
How can I use resize2fs, which does not have that option, to resize such a file system which does not start at the device's beginning?
Answer: The offset option of mount does not get passed to mount directly, but to losetup which sets up a loop device which refers to the offsetted location of the underlaying block device. Mount then performs its operations on that loop device rather than the raw block device itself.
You can also use losetup to make resize2fs play which such file systems:
# losetup --offset=<offset> --find --show /dev/<device>
/dev/loop0
# resize2fs /dev/loop0 <newsize>
# losetup --detach /dev/loop0

(Example may not be complete in means of resize2fs operations)
losetup searchs for the first free loop device (in that example /dev/loop0) as --find was passed. --show outputs that loop device to STDOUT.
Answer: Before I extended an ext4 filesystem from the free space of the beginning of the block device, I performed a search to see how others did it and it looks like your question was the closest match I could find. But the provided answer is not exactly what you have asked or I needed. Because I have just managed to resize/grow from the beginning of the disk successfully, I decided to share my thoughts.
The procedure in a nutshell:
1.) The filesystem to be grown/extended: ext4 filesystem on a partition starting at 1026048 sector and ending at the end of the block device (/dev/sdb in my case)
2.) To allocate the unused sectors at the beginning of the block device for this filesystem, I had to move the data using dd to the start of my future/new partition
3.) Delete the old partition and recreate it with the new start sector
4.) resize2fs to extend to the new partition size
Commands used and details on the method:
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

(Above info revealed by fdisk -l /dev/sdb.)
Calculate dd seek and skip offsets and bs (in our case bs matches sector size):
# dd seek=2048 skip=1026048 if=/dev/sdb bs=512 of=/dev/sdb

So we want to move our data from sector 1026048 and onwards to start at sector 2048 where our new partition is going to start. We should not be able to lose anything as the more we read from the input, the further we get, so by the time we start overwriting with the output (it will eventually reach sector 1026048), we would have copied what was there at the beginning of the device and move on.
Then use fdisk to delete the old partition and recreate it to start at sector 2048.
Once that is done, you can run:
# partprobe /dev/sdb or
# blockdev --rereadpt /dev/sdb
# resize2fs /dev/sdb<num>

to extend the filesystem.
Please, always make backups of your data before doing low-level procedures like that. Failure in some of the steps or system crash or power failure will result in data loss. This is an example which describes a single partition on a block device. Your setups may vary, so do not use as it is. Learn and understand how it works, then test, and if you get the expected results, run on your live data at your own risk!
Hope that helps others as well.
Feedback and where to improve/make more verbose is welcome.
Thank you!

Using resize2fs with file system offset


Find the eigenvalues and eigenvectors of the following square matrix

Question: Given the following matrix: $\begin{bmatrix}2 & 1\\2 &3\end{bmatrix}$ Find the Eigenvalues and Eigenvectors. So I found the Eigenvalues to be 2 and 3. Then I plugged in 2 to find the corresponding eigenvector and got through the homogenous augmented matrix and got $2x_1+x_2=0$ which means $x_1=0$, and I also got $x_2=0$. So is the Eigenvector just $\begin{bmatrix}0 \\0\end{bmatrix}$ Then I tried for find the eigenvector for $3$ and through the augmented homogeneous matrix I got $x_1=x_2$ and $2x_1=-x_2$ so I got this eigenvector to be $\begin{bmatrix}-1 \\2\end{bmatrix}$.
Comment: An eigenvector, by definition, is non-zero. And the eigenvalues you found are false. How did you find them?
Comment: I believe you'll find that your eigenvalues are incorrect: check your characteristic polynomial again (you should have $ \ \lambda^2 \ - \ 5 \lambda \ + \ 4 \ = \ 0 \ $ ) .
Answer: Let $A=\begin{bmatrix}2 & 1\\2 &3\end{bmatrix}$. The roots of the characteristic polynomial for the matrix coincide with its eigenvalues, so we first factor the polynomial:
$$p_A(t)=det(tI-A)=det\begin{bmatrix}t-2 & -1\\-2 &t-3\end{bmatrix}=(t-2)(t-3)-(-1)(-2)=t^2-5t+6-2=t^2-5t+4=(t-4)(t-1)$$
Thus, the roots of $p_A(t)$ are $4$ and $1$, which are the eigenvalues of the matrix. Now to find the $\lambda_1=4$ eigenspace we consider the kernel of the matrix $4I-A$, which is spanned by the vector $v_1=\begin{bmatrix}1\\2\end{bmatrix}$. Similarly, the $\lambda_2=1$ eigenspace of A is the kernel of $I-A$, which is spanned by the vector $v_2=\begin{bmatrix}-1\\1\end{bmatrix}$. Therefore, the eigenvalues of $A$ are $4$ and $1$, with corresponding eigenvectors $v_1$ and $v_2$, respectively.
Also, note that if you are finding eigenvectors of a matrix, and you obtain the zero vector, something has gone wrong and you should retry your calculations, because an eigenvector is by definition nonzero.


ServiceStack OrmLite with multiple Database Servers

Question: I'm building an app around the servicestack framework and need to be able to access data in both Oracle and MS Sql Server.  Is this possible using ORMLite, it seems that I can only set a single dialect for the App or have I missed something?
Answer: Yes it is possible and support for this is already built into the OrmLiteConnectionFactory, see the Master SQLServer + Sqlite shard example on OrmLite's project home page.
Basically you would register your default (or master) connection first with:
var dbFactory = new OrmLiteConnectionFactory(
  "Data Source=host;Initial Catalog=RobotsMaster;Integrated Security=SSPI",
  SqlServerDialect.Provider);

Then you would register a named connection for every other connection you wish to support, e.g:
dbFactory.RegisterConnection("shard-1",
  "~/App_Data/{0}.sqlite".Fmt(shardId).MapAbsolutePath(),
    SqliteDialect.Provider);

Once that's configured, opening a connection without specifying a name will open a connection to the default database, e.g:
using (IDbConnection db = dbFactory.OpenDbConnection()) { ... } //Default DB

Whilst you can specify a name to open up a named connection to a db with a different provider, e.g:
using (var dbShard = dbFactory.OpenDbConnection("shard-1")) { ... } //Named DB

Manually use different Dialect Providers
The differences between the SQL Provider implementations between different RDBMS's are contained within each dialect provider. So if you want to use OrmLite's convenience extension methods against an specific ADO.NET provider implementation you just need to assign the ThreadStatic DialectProvider you wish to use, e.g:
OrmLiteConfig.DialectProvider = SqlServerDialect.Provider;
var dbConn = new SqlConnection(SqlServerConnString);
dbConn.Select
(); //All db access now uses the above dialect provider

This is essentially all what RegisterConnection in OrmLiteConnectionFactory automatically does behind the scenes for you.
For reference here are all the dialect providers for OrmLite up to this point:

SqlServerDialect.Provider
SqliteDialect.Provider (different 32/64 and Mono impls available)
MySqlDialect.Provider
PostgreSqlDialect.Provider
OracleDialect.Provider
FirebirdDialect.Provider
Comment: Brilliant, thanks for the quick response.  I hadn't spotted that within the named connection I could specify the dialect. I'll give it a go.
Comment: Please don't post code in comments. Create a new question and show exactly what you're trying to do and the full exception details.
Comment: Weird thing that happened to me regarding using two connections in the same factory that happen to use different dialectproviders: If I opened a transaction on the secondary connection and committed it but neglected to dispose of the transaction, subsequent usage of the first connection would utilize the dialect of the second. Properly disposing of transactions resolved my issue.


Are sheaves (co)algebras for a (co)monad?

Question: I remember reading somewhere that sheafification is a (co)monad on the topos of presheaves. If indeed this  is true, then can we characterize the category of sheaves as the Eilenberg-Moore category of (co)algebras for this (co)monad?
Answer: Sheafification is a monad simply because the sheafification functor $L$ is left adjoint to the inclusion $i$ of sheaves into presheaves. In fact, this is an idempotent monad: $iLiL\cong iL$ since nothing happens when you sheafify a sheaf. Idempotent monads are equivalent to reflective subcategories, i.e. full subcategories for which the inclusion admits a left adjoint, so this result isn't particularly about sheaves.
Comment: It might be helpful to explain or give a reference for this correspondence. Do you have any comments about the Eilenberg-Moore category?
Comment: @MorganRogers Sorry for the lack of references. The equivalence between reflective subcategories and the Eilenberg-Moore algebras for idempotent monads is pretty well known; I'd start at the nLab page for reflective subcategories. In particular, sheaves are the Eilenberg-Moore category.
Answer: Let $Sh(X)$ be a category of sheaves over topological space $X$. For given sheaf $F$ over $X$ and for given point $x\in X$, the stalk of  $F$ at $x$, denoted $F_{x}$ is: $F_{x}=\underset{U \ni x }{\varinjlim}F(U)$  the direct limit is indexed over all the open sets containing $x$, with order relation induced by reverse inclusion (  $U<V$, if  $U\supset V$). That way we get the functor $J$ to the category $Sets^X$ (here $X$ is viewed as discrete category) or equivalently to the category $Sets/X$ (For given $(S_x)_{x\in X}\in Sets^X $ construct the natural map $\{\underset{x\in X}{\coprod S_x}\to X\}\in Sets/X $, conversely take a preimage of each $x\in X$. That is  $Sets^X \cong Sets/X$.)
Now for given map $f:A\to X$ take sections of $f$. The family of all sections form sheaf over $X$. It gives a functor $R$ to $Sh(X)$.
So  $G=J\circ R$ is a comonad on the category $Sets^X$ and sheaves are coalgebras over the comonad if it helps you somehow.


Prologue with Ruby on Rails 3

Question: I'm a total newbie to RoR and am trying to get the Prologue gem up and running. I've downloaded the prologue zip file from github.com/quickleft/prologue and am trying to follow the instructions in the associated readme file. I have encountered a number of issues....
Q1: What do I actually do with the extracted zip file? For instance, am I supposed to place the extracted files inside specific rails application directories or what ?
I've  been able to install the gem by executing "gem install prologue". However, I cannot create a new application using the "prologue new my_app" command - the following message is displayed at the command prompt when I execute that command:
*C:/Ruby192/lib/ruby/gems/1.9.1/gems/prologue-0.3.10/lib/prologue/cli.rb:58:in ``
': No such file or directory - git config --global user.name (Errno::ENOENT)
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/prologue-0.3.10/lib/prologue/cli.rb:58:in `git_user_name'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/prologue-0.3.10/lib/prologue/cli.rb:33:in new'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thor-0.14.6/lib/thor/task.rb:22 :inrun'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thor-0.14.6/lib/thor/invocation.rb:118:in invoke_task'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thor-0.14.6/lib/thor.rb:263:in dispatch'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thor-0.14.6/lib/thor/base.rb:38
9:instart'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/prologue-0.3.10/bin/prologue:4: in <top (required)>'
from C:/Ruby192/bin/prologue:19:inload'
from C:/Ruby192/bin/prologue:19:in `'*
Q2: Does anyone have any advice on how to overcome this problem?
Q3: Also, when attempting to get prologue up and running is it possible to do this without integrating it into an existing rails application? If so, how?
(I have ruby 1.9.2 and rails 3.0.0 installed on a Windows Vista machine)
Advice/feedback on the above issues would be greatly welcome!
Comment: Do you have Git installed on this system?  May be part of the problem...
Answer: It seems that Prologue needs 'thor', another gem. You can install all dependencies with the command 'bundle install'.
You can integrate Prologue in a new Rails app, but you definitely need some (existing or new) Rails app to run it.

Prologue with Ruby on Rails 3


Green clubs and blue diamonds

Question: I really like the idea of making and playing cards with blue diamonds and green clubs. Each color is a separate color then.
Is there some arguments against it? Do you know some games where this would be a bad idea?
Comment: Note that your choices of colours aren't color-blind friendly
Comment: https://www.amazon.com/Four-color-Deck/dp/B07BZW6QCY
Comment: German Cards have green (leaves) istead of black spades: https://en.wikipedia.org/wiki/German_playing_cards
Answer: There are already some games that use this type of deck; such as Tichu. A Tichu deck contains 4 suits in 4 different colors (although they are not the same traditional 4 suits).
For most games out there; this idea would make the games slightly easier to play; because it would be easier to distinguish a Spade from a Club, and a Heart from a Diamond. Most traditional trick-taking or melding games would benefit from this.
However, there are a few games where not only suit, but color, also matters:
Canasta - Red 3s have separate rules from black 3s. It doesn't matter whether a 3 is a Spade or a Club, but it does matter if it's black. To play Canasta with your custom deck; you would have to remember that both a Club and a Spade have one rule, while a Heart and a Diamond have another rule.
Klondike Solitaire - Red cards can be moved onto black cards and vice-versa. So again, this would be more difficulty to play with your custom deck; as you would have to look for cards of 2 different specific suits rather than just look for cards of a specific color.
Comment: Also Euchre, where the jack of the same color as the trump suit becomes part of the trump suit

Green clubs and blue diamonds


Is the word 'hussler' appropriate?

Question: Is wassup hussla? (also gangsta, killa etc.) appropriate to say to a friend or a colleague?
I mean, I know that it's not any sort of an official phrase I'd say to my boss. What I mean to ask is whether this word may be taken offensively, like nigger in the US.
Comment: This is really a case of "if you have to ask, then the answer is 'no'". This is something that should be clear based on observing the group you are in. I can't think of anything more irritating than a colleague or friend who calls people *hussla* all the time. And you should be able to tell if it is okay in your circle of friends, because you should be hearing them say it already.
Comment: I was mostly seeing it as an ice breaker. Like these situations where everybody is formal simply because nobody knows anyone. But the fact that you'd be irritated means that at least one person wouldn't like it, which in turn makes me reconsider.
Comment: @Kosmonaut Irritating and offensive are two different things, so while it may be irritating to have a friend call everyone something ("dude", "hussla", "bro") that doesn't make it offensive.
Comment: Would be appropriate for Sales Staff, is basically their job description.
Answer: The word is hustler, and it can be very appropriate depending on the situation. At it's broadest, it means nothing more than "somebody who will put in the effort necessary to get things done". In the darker corners of the streets, it carries a different connotation ("one who will do anything to make a deal"), but the word lives a respectable life in the suburbs as well.
Killer may be an appropriate nickname as well -- it doesn't necessarily mean, well, a killer. It could mean nothing more than, say, a reliable closer in a sales department.
Gangster (or any street-spelling variation thereof) is probably not appropriate for the workplace -- even if your are working for, um, "legitimate businessmen" whose legitimate businesses seem to do very little actual business. They have their own preferred vocabulary, and it doesn't involve interesting any outside parties who ought to stay disinterested.
Comment: It's the same word -- the double-ess spelling is a hip-hop-esque misspelling. It's jess kooler 2 stick it to the man than to use a dictionary.
Comment: ok, thank you a lot for your input! Now I'm going to call everyone killas and husslas!
Comment: +1 for *"legitimate businessmen" whose legitimate businesses seem to do very little actual business*: made me smile.
Comment: Based on the UD poster's inability to spell half of the words in the post and the 50/50 up down vote, I would not use this particular entry for anything except perhaps as a bad example...
Comment: This might be a bit confusing, because the word I had in mind was http://www.urbandictionary.com/define.php?term=hussler So it is misspelled in the question, right?
Answer: Everything can be taken as offensive.  Some may confuse your "hussler" with the porn magazine, and thus take offense.
It can be... nah, I can't get myself to call "appropriate".  "Inoffensive" it may be, but even though I'm generally used to very informal workplaces, I wouldn't call a co-worker "hustler".  It doesn't just depend on the workplace, it depends much more on how friendly or maybe even close you are to/with your co-workers.
Or are you working in a pharmaceutical company?  You know, with other "drug dealers"? ;-) Then it may... well, it would still be extremely informal.
Comment: I don't think anyone would confuse it with the magazine in that context.
Comment: @advs If they *got* the whole context, probably.  But if someone walks past you just as you said "Hustler"... they could think you said *that*, and take offense.
Comment: Perhaps, but I would say it's pretty low-risk.

Is the word 'hussler' appropriate?


mysqld_safe mysqld from pid file /data/mysql/mysqld.pid ended

Question: MySQL is restarting by itself, but it's crashing most of the time. I am unable to restart the instance due to a pid issue.
Tried to restart MySQL

moving original ib* files to _old - this time MySQL is started
stopped MySQL and moved the _old to original state
restarted instance again - it's throwing an error pid ended

MySQL version is 5.6.21
From error log :

150713 11:39:42 mysqld_safe Number of processes running now: 0
  150713 11:39:42 mysqld_safe mysqld restarted
  2015-07-13 11:39:42 0 [Warning] Using unique option prefix lower-case-table-name instead of lower_case_table_names is deprecated and will be removed in a future release. Please use the full name instead.
  2015-07-13 11:39:42 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
  2015-07-13 11:39:42 21262 [Note] Plugin 'FEDERATED' is disabled.
  2015-07-13 11:39:42 7fac432cf780 InnoDB: Warning: Using innodb_additional_mem_pool_size is DEPRECATED. This option may be removed in future releases, together with the option innodb_use_sys_malloc and with the InnoDB's internal memory allocator.
  2015-07-13 11:39:42 21262 [Note] InnoDB: Using atomics to ref count buffer pool pages
  2015-07-13 11:39:42 21262 [Note] InnoDB: The InnoDB memory heap is disabled
  2015-07-13 11:39:42 21262 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
  2015-07-13 11:39:42 21262 [Note] InnoDB: Memory barrier is not used
  2015-07-13 11:39:42 21262 [Note] InnoDB: Compressed tables use zlib 1.2.3
  2015-07-13 11:39:42 21262 [Note] InnoDB: Using Linux native AIO
  2015-07-13 11:39:42 21262 [Note] InnoDB: Using CPU crc32 instructions
  2015-07-13 11:39:42 21262 [Note] InnoDB: Initializing buffer pool, size = 16.0G
  2015-07-13 11:39:43 21262 [Note] InnoDB: Completed initialization of buffer pool
  2015-07-13 11:39:43 21262 [ERROR] InnoDB: Space id in fsp header 1416128883,but in the page header 824195850
  06:09:43 UTC - mysqld got signal 11 ;
  This could be because you hit a bug. It is also possible that this binary
  or one of the libraries it was linked against is corrupt, improperly built,
  or misconfigured. This error can also be caused by malfunctioning hardware.
  We will try our best to scrape up some info that will hopefully help
  diagnose the problem, but since we have already crashed,
  something is definitely wrong and this may fail.
  key_buffer_size=8388608
  read_buffer_size=2097152
  max_used_connections=0
  max_threads=1000
  thread_count=0
  connection_count=0
  It is possible that mysqld could use up to
  key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 2325895 K  bytes of memory
  Hope that's ok; if not, decrease some variables in the equation.
  Thread pointer: 0x0
  Attempting backtrace. You can use the following information to find out
  where mysqld died. If you see no messages after this, something went
  terribly wrong...
  stack_bottom = 0 thread_stack 0x30000
  /opt/mysql/server-5.6/bin/mysqld(my_print_stacktrace+0x35)[0x8f8bb5]
  /opt/mysql/server-5.6/bin/mysqld(handle_fatal_signal+0x494)[0x67aba4]
  /lib/x86_64-linux-gnu/libpthread.so.0(+0x10340)[0x7f8cdbd3d340]
  /opt/mysql/server-5.6/bin/mysqld[0xb3f6bb]
  /opt/mysql/server-5.6/bin/mysqld[0x9ba3c7]
  /opt/mysql/server-5.6/bin/mysqld[0xa65793]
  /opt/mysql/server-5.6/bin/mysqld[0xaa7016]
  /opt/mysql/server-5.6/bin/mysqld[0xaa921c]
  /opt/mysql/server-5.6/bin/mysqld[0xa17148]
  /opt/mysql/server-5.6/bin/mysqld[0x960b3d]
  /opt/mysql/server-5.6/bin/mysqld(_Z24ha_initialize_handlertonP13st_plugin_int+0x48)[0x5baa58]
  /opt/mysql/server-5.6/bin/mysqld[0x705bf1]
  /opt/mysql/server-5.6/bin/mysqld(_Z11plugin_initPiPPci+0xbf6)[0x70a8a6]
  /opt/mysql/server-5.6/bin/mysqld[0x5ad89d]
  /opt/mysql/server-5.6/bin/mysqld(_Z11mysqld_mainiPPc+0x3e5)[0x5b2855]
  /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7f8cda921ec5]
  /opt/mysql/server-5.6/bin/mysqld[0x5a4bd9]
  The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
  information that should help you find out what is causing the crash.
  150713 11:44:34 mysqld_safe mysqld from pid file /data/mysql/mysqld.pid ended
Answer: Make a clean attempt:
remove ibdata and iblog files (present)
copy ibdata file (original)
chown mysql:mysql /datadir/ -R
start mysql

and then check the error log once again.
Make sure your ibdata and iblog files are placed in correct location. Share your innodb parameters.
I saw a bug report similar to your description: http://bugs.mysql.com/bug.php?id=69623 (Though version appears older)
For now, if you have backup + binary-logs then you can restore from backup and play binary logs again to catchup to latest.
Monitor for next crash and if it appears try to identify what actions caused crash. Check binary-log for DML/DDL...
Upon crashes you might want to enable general query log to further review what was going on before the crash.
Answer: Yeah i have tried with above steps. but still i am facing same error like "mysqld from pid file  /mysqld.pid ended"                                                                       Innodb variables                                                                   innodb_use_native_aio = 0
innodb_buffer_pool_size         = 16G
innodb_log_buffer_size          = 8M
innodb_log_file_size            = 128M
innodb_file_per_table           = 1
innodb_max_dirty_pages_pct      = 90
innodb_read_io_threads          = 16
innodb_write_io_threads         = 16
innodb_thread_concurrency       = 24
innodb_additional_mem_pool_size = 20M
innodb_file_per_table


Type II singularities for 3D Ricci flow

Question: I know that type II singularities of the Ricci flow can exist on closed 3-manifolds (e.g. on $S^3$), but on the other hand it seems to me that ODE comparison combined with Hamilton's tensor maximum principle implies that in 3D Ricci flow, there can be no type II singularities.
Please explain where the following argument is flawed:
In 3D Ricci flow, the Ricci tensor evolves by
$$
\frac{\partial R_{ij}}{\partial t}=\Delta R_{ij}-Q_{ij},
$$
where $Q_{ij}=6R_{ij}^2-3RR_{ij}+(R^2-2g^{kl}R_{kl}^2)g_{ij}$ (see Hamilton's 1982 paper, section 8). Writing the Ricci tensor as a diagonal matrix $R_{ij}=\mathrm{diag}(\lambda,\mu,\nu)$, $Q_{ij}$ is also diagonal and the top left entry is
$$
2\lambda^2-\mu^2-\nu^2-\lambda\mu-\lambda \nu+2\mu\nu,
$$
The other entries are obtained by permuting $\lambda, \mu,\nu$.
Claim 1: Now, for any solution of the ODE system
$$
\frac{d}{dt}(\lambda,\mu,\nu)=-Q(\lambda,\mu,\nu),
$$
there exist constants $C,T>0$ (determined by the initial conditions) such that the solution can blow up no faster than $\frac{C}{T-t}$ (the type I rate). (This is because $Q$ is quadratic in $\lambda,\mu,\nu$.)
Define the closed subset $\mathcal{Z}$ of the product space of $3\times3$ symmetric matrices (of Ricci curvature tensors with eigenvalues $\lambda\geq \mu\geq \nu$) and the time axis by the inequalities
$$
\lambda\leq\frac{C}{T-t}, \qquad \qquad \nu\geq -\frac{C}{T-t}.
$$
For suitable choices $C,T>0$ (depending only on the initial conditions), $\mathcal{Z}$ is preserved by the ODE, is closed, and is invariant under parallel transport (it is defined by conditions on eigenvalues). Moreover, for any fixed $t$, the time-slice $\mathcal{Z}(t)$ is convex. (Hamilton 1999 constructs a similar $\mathcal{Z}$ in his proof of the Hamilton-Ivey pinching estimate.)
Claim 2: By Hamilton's tensor maximum principle, the Ricci flow preserves the set $\mathcal{Z}$. Therefore the eigenvalues of the Ricci tensor under 3D Ricci flow cannot blow up faster than the type I rate.
Answer: The type-I condition is that for some $C > 0$ we have $|Rm| < \frac{C}{T_{sing} -t}$ where $T_{sing} < \infty$ is specifically the supremum of times such that $|Rm|$ is bounded.
In the type-II case, it will turn out the $T$ you get from your ODE estimate must be smaller than $T_{sing}$.  (Indeed, if you just try to get such a $T$ from this route, it will nearly always be smaller).  When $T < T_{sing}$ the estimate you get will not work at the singular time.

Type II singularities for 3D Ricci flow


How many types of pieces or icons are in Dashpaad (10x10 board)?

Question: Dashpaad board (10x10 square blocks) have 100 squares in total. How the pieces fit in this board and what are their names.
Answer: Dashpaad board (10x10 square blocks) have following type of pieces:
1 इंद्र Indra (King)
1 मंत्री Mantri (Minister)
1 नारद राजऋषि Naarad or Raajrishi (Noble Man)
1 सेनापति Senapati (General which became Queen)
2 महारथी Maharathi (Rooks)
2 शूरवीर Shoorveer (Knights)
2 गज आरोही Gajarohi (Modern Bishop)
8 पद्ति Padati (Pawns)
4 चारक Chaarak (Impersonator or Spy)

King and Minster falls under same Royal category.
Noble godman falls
under Immortal Category.
General is the commandar of Army.
Normal Officers.
Common people.
Impersonator can copy anyone step.

No piece can exceed its count. For an example, this means that there can be only 1 General and only 2 Bishops as total.
To understand the categories and all these pieces, explore  other related questions in this portal. Also, Kautilya Arthshastra book is a good read.
Comment: Do you have a source/reference for these information?
Comment: These cloth and stone based boards are in museums now. The game is limited to few people. I learnt in 2005 and noted down all points. If you will got through the summary of Kautilya Arthshastra then you will learn the game. Learn 6 principles.. For references, Mahabharat has this game named as Dhyut. But last four Corners called naaglok have no clue to anyone till now.. Even some ancient samples are uncovering