The coolant is boiling when I shut off engine

Question: I have a 2000 Chrysler 300m. A few days ago out of the blue my car cut off on its own and I was unable to start it for a few hours. I left it sit in the grocery store parking lot. Went back 3 hours later and it start right up. Five miles down the road it started overheating bad. It started to stutter and had a loss of power. The next day I took it to shop and was told that the water pump was going bad, the hose need changing, and the timing belt. The price was crazy so I took it to another well known shop. They did the work for half the price. They had the car running for 2 hours and it was fine. I picked it up from the shop and drove maybe 50 miles that evening and it was fine. This morning I drove it 15 miles and when I turned it off, I heard the boiling sound. After it cooled off it needed 4 large cups of water. I drove it home and it was boiling again.
The mechanic that did the work said the water was really nasty in the pump. I am so over not knowing if I will be able to get my kids to school. Thank you in advance for any responses.
Comment: It was boiling because there was not enough water to cool down the engine, so it passed the boiling point of the water even under pressure. Use a 50/50 coolant, water (especially tap water) is bad for the engine by itself. As for the coolant being low, check for leaks under the car after you park it. If it is leaking or if you continue to need to add more coolant, take it back to the shop who did the work and have them fix it.
Comment: At any time during all this, did the "TEMP" light on your dashboard illuminate? Or, if you have a gauge, did the gauge read above normal? Oh, and... ***please*** use antifreeze/coolant mix instead of straight water.
Comment: Can you rephrase your question , its not clear as to what you are asking.
Comment: Kim, I suspect it's not a terminal problem (just super annoying). See my answer below.
Comment: similar:  http://mechanics.stackexchange.com/questions/17560/95-corolla-overheats-probable-coolant-leak-or-maybe-thermostat-need-more-advic
Answer: tl;dr: this might be as simple as a bad radiator cap.
Funnily enough, I am currently experiencing similar issues with my (completely different) car. I smelled coolant, looked under the hood and saw this:

Even with new coolant, I noticed that it was boiling out of the overflow pipe.
So, what does this tell me?  I'm almost certainly losing pressure somewhere in the system which, due to the ideal gas law, allows the coolant to reach boiling point even though the car isn't overheating.
What should you do?  Get the car hot, open the hood and then listen carefully in various places over the engine (obviously it's hot, so watch out under there).
My suspicion is that you'll hear exactly what I do: hissing right at the radiator cap.  The solution is pretty simple:

Buy the replacement cap for about $20 USD.
Wait for the car to cool off.
Replace old cap with new.
Top off coolant.
Drive around enough to get it hot.
Confirm no boiling and no hissing.
Go to the shop and have them flush the coolant.  Tap water is not good for the cooling system. You should always use a proper mixture (and Home Depot Prestone is probably fine).
Come back here and brag about how you fixed it. :-)

Good luck. Many of us are parents and feel your pain!
Comment: Good instructions. I'd also say the cap needs to be not only good but tight.
Answer: Overheating can be caused by several things. First, make sure you are actually overheating, that is the temperature gauge tells you the coolant is too hot.  (See Bob Cross's answer).
If it IS too hot, it could be caused by 1) bad thermostat  stuck closed  2) bad/clogged radiator  3) bad water pump.
A bad thermostat will also cause a fairly rapid overheat, and usually a cold or cooler than normal heater.
A clogged radiator is more frustrating to diagnose because you do NOT want to open the radiator while it's hot.  If it IS a bad radiator, get a NEW one, not a rebuilt one.
A bad water pump will usually be making a squeaking noise.  You will also be able to see coolant leakage on or around the pump.  Some water pumps are easier to change than others, and you don't necessarily need to change the timing belt.  Depends on how much mileage the timing belt has on it.  And DO NOT let a tire store or Wal-Mart do that work.  Find a shop where they make their living doing mechanic work.
Finally, if you need to add fluid to the coolant system, use either pre-packaged 50/50 non-silicate antifreeze or a 50/50 mix of full strength and DISTILLED water (really cheap to get at the grocery store). Don't use tap water unless it's an emergency.
Answer: Are the cooling fans running when its overheating? I've seen plenty of Chryslers over heat from fan failure. Other possible cause would be the head gaskets. The water pump was probably leaking, but when it started to run rough and died you may have caused a leak in the head gaskets
Answer: So - I had exactly this problem on my 2003 Mazda Protege 5, 150K miles.   I also happen to live in AZ where summers are 115F.  When I would turn the car off after a bit of a drive, the temp gauge in the car was at medium.  However, after about 30 seconds of being off, the coolant started to overflow and boil into the spare holding tank.  And the boiling was vigorous in there.
I went to Autozone, got a $10 radiator cap, put it on, and the problem stopped.
Thus, my radiator cap was faulty - and was letting fluid out at too low a pressure (which happened to be less 16 psi per the rating on the cap).
Want to thank this forum for saving me a trip to the mechanic.  Cheers!
Answer: I'll agree that coolant is boiling because there's probably not enough of it in the system. So if you fill/check it and know it's full, and drive a while and the boiling happens then the coolant is going someplace. Where it's going is what you need to find out.
Your original problem seemed to be a bad water pump, and that was replaced which seemed to fix the overheating, but don't rule out that the recent work you had done could have introduced a new problem. A poorly installed gasket for example could work fine for a while and then start leaking coolant.
I can't speak to the shops involved, but objectively if some place can do the same job for half the price, that can sometimes means a) the work they do isn't as good, b) the parts they use are probably cheaper, and maybe not as good, or c) they are cutting corners, like maybe not changing the coolant out or checking everything over as well.


Why would I want to a use baseline grid in Illustrator cc?

Question: What are the benefits be of using a baseline grid in Illustrator for a limited amount of text?
Comment: Same as it is for any other amount of text?
Answer: tl;dr: the baseline grid is useful to align other, non-text objects to your text baselines to give your layout a very tight vertical rhythm.
A baseline grid is not just a tool for setting text in such a way that line-spacings are proportional and match in a single document. It also is a powerful tool in placing and aligning non-text objects in the layout.
One of the much-overlooked aspects of layout is that it's not just important to ask yourself where you place an object, but also why there. A very good 'why' is 'it aligns with something that was already there'.
Any layout, even one without any text, even an empty one, already has places to align to that are 'already there'. The paper edge, the margin, the mathematical centers; the golden ratio or the Rule of Thirds if you want to go fancy an draw some guides.
I always say that I'm looking for 'excuses' to put something where I put it. All those examples I just named are perfect excuses to align to. I am always looking for more lines, more excuses to which I can align objects. The baseline grid gives me tens of new horizontal excuses.
If you use the baseline grid to align non-text objects to your text baselines, you will reinforce the vertical rhythm that has been dictated by the grid. A lay-out just looks that much better when the edges of images align to text baselines. If you establish a vertical rhythm with a baseline grid in your text, and then break that by misaligning the edges of non-text objects, that's bad design. You have a multitude of aligning excuses in your grid. Use them.
Answer: Depends what 'limited amount of text' would mean, but in my experience a baseline grid makes sense for large documents and when the cost for the job can cover all the detailing (extra hours) involved with using a baseline grid and adjusting content to it. For a couple of pages i will not bother with this, but this is just a personal option.


How do I figure out who issued a credit card from just the first 4 digits?

Question: I had a big refund issued to an old cancelled Visa card.  The merchant gave me the first and last four digits.  How can I find out more about this old card?  Merchant said the refund had been accepted but I haven't gotten a penny.  I cut up and discarded card months ago.
Comment: Don't you have any credit card statements? Did you actually close your accounts, or just cut the cards up? If they accepted the refund, your account is probably still open. Have you tried logging into your accounts online?
Comment: Sounds like the Dave gave you bad advice when he told you to cut up all your cards.
Answer: The first six digits of the card are known as the BIN (or IIN).  They can be used to identify who issued the card, and sometimes what type of card it is.  This lookup service would help, but it requires all six. Just the first four won't work unless you want to try all 100 possibilities.   Even with that, you only might be able to tell what bank issued the card, which is something you should probably be able to remember in the first place.
If the merchant issued a refund to what is effectively the wrong card, because they didn't bother asking you for your current card (the one they had on file was likely expired anyway, if it's that old), then it's up to them to get that money back and reissue your refund.   If, however, it's an account you still have open in your name (even if you don't have the physical card) the merchant is in the clear and you have to do your homework with old statements or credit reports to track down that account.
Comment: I edited the title. The OP didn't know how to figure out which card got the credit from a merchant.
Answer: Check your email or your snail mail for a statement or message telling you the last four digits of your old cards. These messages would have been telling you a new statement was available, or that a new card was being issued.
You were either transferring money to pay the bill or paying by check. That means the check or electronic transfer would have left a trace in your bank account. Check your bank website or account statements for payments to credit cards. There might be enough information to be able to identify the correct card.
If you didn't get a paper monthly statement you would have been logging into a website, and the login still might work.
Answer: Here's a wikipedia page which unfortunately was deleted and is out of date. You can look for other sites that will allow credit card merchant lookups, but most that I'm aware of required paid access. Good luck getting your refund.
Answer: Ask the issuer
If you don't know the numbers, then the only one who'll know it will be the institution/bank who issued that card. It's likely that the merchant itself has no more information than they gave you, as it's recommended to not store the full card number and they can do a refund based on the transaction reference IDs.


Example of existence proof in dependent typing?

Question: I understand that $\Pi$ types are generalizations of functions and can be interpreted similar to $\forall$ in logic. I also know that $\Sigma$ types are generalizations of tuples and can be interpreted similar to $\exists$ in logic. But whereas I find it easy to imagine $\Pi$ type examples by thinking in Haskell, I am having a hard time thinking of good examples of $\Sigma$ types. Is there a particular "canonical" $\Sigma$ type that gives a good indication of how it can be interpreted as existence when the type is thought of as a proof?
Answer: $\Sigma$-types in Haskell appear in various places. Because Haskell is not dependently typed, they often reduce to the non-dependent version of $\Sigma$-types, which are just Cartesian products. So whenever you see an ordered pair, or a record, that is a simple case of a $\Sigma$-type.
At the level of a modules there can be dependencies and so we get actual $\Sigma$-types. For instance, a module which defines a type $T$ and then a value $f$ of type $T \to T$ has the kind $\Sigma_{T : \mathrm{Type}} (T \to T)$. (The module should hide the definition of $T$ in order for this to actually be the case.) Observe that this is a "large" dependent sum because it ranges over "all Haskell types $T$" so I refer to it as a "kind". In fact, the theory of modules is based on the observation that hiding bits of a program behind a layer of abstraction is precisely the same as forming a dependent sum.
Haskell has existential types. These are like depenent sums of the kind I mentioned above. Namely, an existential type
data Calf = forall t . Bull t => Cow(t)

is just a confusing way of writing $$\mathtt{Calf} = \textstyle \sum_{t : \mathtt{Bull}} Cow(t).$$ Strangely, the "forall" keywords indicates the fact that there exists a type $t$ of class $\mathtt{Bull}$ such that $F(t)$. Perhaps some Haskellites can explain the logic behind the notation to me.
Comment: There is no deep logic behind the notation, other than it being a forall in a negative position: $(\forall t. \mathrm{Bull}(t) \Rightarrow \mathrm{Cow}(t)) \equiv \mathrm{Calf}$
Comment: Sorry, but the only equivalence like that I am aware of is that $(\exists t . \phi(t)) \Rightarrow \psi$ is equivalent to $\forall t . (\phi(t) \Rightarrow \psi)$. Notice how $\psi$ does not depend on $t$. Are you talking about something else?
Comment: Well no, but in this case $\psi$ is $\mathrm{Calf}$ and not $\mathrm{Cow(t)}$. The type is $\forall t. \mathrm{Bull}(t) \Rightarrow \mathrm{Cow}(t)\Rightarrow \mathrm{Calf}$ which is equivalent to $(\exists t. \mathrm{Bull}(t)\wedge\mathrm{Cow}(t))\Rightarrow \mathrm{Calf}$. Sorry for the confusion.
Comment: I don't think this is quite true.  The existential in haskell is not exactly a $\Sigma$.  A sigma is the dependent version of the connective $\&$ (pronounced ``with") which is negative, while the haskell existential is more like a dependent (except we erase types, so the first argument disappears) version of $\otimes$ and is positive.  We can't express sigma (even when the first argument is a type) in Haskell, because the projections are not typeable without dependent types.  On the other hand, ML modules are real sigmas (but at the cost of no longer being first class).
Answer: Well, how about the proof that every number is zero or has a predecessor? It turns into a function which takes as input an integer, and as output returns either a proof that it is zero, or the predecessor, and a proof that it is indeed the predecessor.
In Coq:
Fixpoint pred (n : nat): {n = 0} + {exists m, S m = n} :=
match n with
| 0 => left (eq_refl 0)
| S m => right (ex_intro _ m (eq_refl (S m)))
end.

Eval compute in (pred 12).
> right (ex_intro (fun m : nat => S m = 12) 11 eq_refl)

In Coq, $\{\_\}+\{\_\}$ is the Either type of Haskell, and exists is just $\Sigma$. You can see that the function matches on the integer, and returns the proof of $0 = 0$ in the first branch, and the pair $(m, p)$ where $p$ is a proof of $m+1 = n$ in the other branch (ex_intro is just a special pair constructor for exists. The predecessor of 12 is correctly computed to be 11 in the following call.


00 honda accord ex 3.0 coupe fuel pressure problems

Question: My car was caught in the flood that we recently had about a week ago in west phx, az. My car starts, runs, but in the flood my car got water in the oil pan, tranny, so I gave it an engine flush treatment, changed spark plugs, changed engine oil, tranny oil, n thought I could change fuel filter withouth having to change fuel pump.  Not podsible! Anyhow my car starts, runs but runs like if trying to get or Its not getting any fuel pressure going through the gas line. Itll let me drive it upto 6 or 7 miles then when pressing gas car wont move especially if going uphill. What could be causing this to happen? What can I do that I havent done to fix this problem
Comment: I'm wondering if you didn't get water into your exhaust and therefor your catalytic converters are plugged. Does it feel like it will only allow the engine to rev to about 2000-2500 and then just want to not go any faster (in park/neutral)?
Answer: I agree with Paulster2, it's very probably that you have water trapped in your exhaust.  After it runs for a few minutes, is there any steam coming out of the tailpipe?  A little steam is normal after first start up but after the engine warms up it should stop.  If you have a never ending source of steam you can take apart the exhaust system and dump it out (or if you really don't care, poke holes in the low spots).
If you really think it's a fuel pressure issue you can buy a gauge at pretty much any auto parts store and check the pressure off the fuel rail.  It's also possible you have some water in your gas tank, and that's what's causing it to bog.  The solution then would be to siphon out the gas and put new in.
Answer: Most auto part stores will loan enough tools to test what's wrong. Check your fuel pressure, your cylinder compression, and make sure your ignition system doesn't have water damage.
If there are any DTCs those would help pinpoint the exact problem also.


Where is Elizabeth in the end of At World's End?

Question: Where is Elizabeth in the end of At World's End? Will gives her his heart to protect and leaves her on some island. Is it Davy Jones' locker?
Answer: As per wikia, she is at Port Royal. Check out the epilogue on above link page:

Epilogue
Ten years later, Elizabeth and her son, young Will Turner reside in Port Royal.Young Will sings a pirate song, with Elizabeth following behind. They both stand at the edge of a cliff, looking at the horizon, waiting for the sun to set. Finally, they see a flash of green light as the Flying Dutchman reappears, signifying Will Turner's return from the Land of the Dead.

However, I am not able to understand where it is shown that this place is Port Royal. My understanding for that scene is only that Will is not bounded to ship and uses his one day in ten years to meet Elizabeth who is living somewhere on land with other citizens (not pirates).
Comment: I can't prove it, since I have not read it/seen it, but perhaps the source of the Port Royal reveal is in the junior novelization of the film??


What compound is best to use when skim coating a plaster wall that had wallpaper removed?

Question: What kind of compound is best to use when skim coating a plaster wall that had wallpaper removed. Should it be thinned with water? when would one use Toping Compound instead of joint compound. Light weight compound, blue bucket, or regular, green bucket if going with joint compound
Comment: I need to do something similar soon. I had a few veneer plaster products recommended to me (http://advice.thisoldhouse.com/showthread.php?t=109856) but I can't find any of those locally so might try thinned joint compound (they also make light joint compound I guess, which I will try for this) and can let you know how it goes.

I also heard someone somewhere suggest joint compound mixed with primer.  I tried a small test of this, I mixed it quite thin and ended up painting it on with a roller. But it didn't produce a smooth surface, just coated the rough plaster surface.
Answer: I've used regular joint compound, thinned with water quite a bit. Be careful with any areas where the wallpaper pulled up the outer layer of drywall and exposed the brown paper - those will tend to bubble up when you skim over them. You might have some success with painting over those areas with something like Kilz, but even then, you might get bubbling. In that case, I use a utility knife to cut out the offending bubbles, and skim again. Thin coats should help reduce instances of bubbling.
Comment: Is this good for plaster, as the OP is asking about?  I.e. will joint compound adhere well to a whole wall of plaster, or just drywall?
Comment: I actually didn't notice that it's a plaster wall. I haven't used joint compound on a plaster wall, but hopefully someone else has and can confirm whether or not that will work. If I had to guess, I'd say it will work.
Answer: General purpose compound will work fine. Be sure to read the label as some manufacturers specificaly state "Not for Skim Applications".
As said by the others, thin with water and mix well with a large drill and paddle to remove as many air bubbles as possible before attempting to apply. You can also add a few ounces of Ivory dish soap to the mix. It will really make the mud glide on smoothly with fewer tiny pock holes. I prefer a good 12 inch knife to a trowel, and dipping it in water before final pass helps make a smoother surface.  If you do need to put on a second coat, which is almost always the case, be sure to knock down any trails or ridges with a drywall knife and lightly sand the surface to remove boogers and loose dried mud.  clean the entire surface with a damn sponge, rinsing the sponge often. This will remove all the dust that will cause the skim mud to curl off the wall during application.
Once you are happy with the final finish, be sure to prime using a PVA primer or other primer specificaly described to be used on new drywall. What you are doing is sealing the mud so the water in your latex paint won't be absorbed into the mud, lifting it and ruining all your hard work.  Good luck.
Answer: You can use regular "all-purpose" joint compound.  If you are going to thin with water, I would do it very sparingly (to avoid the compound sliding off the bottom of the knife when moving horizontally).
After skim coating and sanding, apply a coat of primer to seal up the compound before painting.
Answer: This suggests joint compound but still not sure if there is something else that might be better for some reason: http://www.thisoldhouse.com/toh/asktoh/question/0,,455195,00.html
Answer: There is a product sold by Sherwin Williams its a solvent based spackleing its similar to joint compound but it bonds a lot better than Sheetroc mud and dries very hard very much like plaster.


Why does my MacBook Pro take so long to go to sleep?

Question: Until recently, when I pressed Option-Cmd-Eject, my MacBook Pro used to go to sleep almost immediately (e.g. within three or four seconds). It's a MBP 8,2 with an SSD and 8GB RAM.
Since a week or so, it takes much longer; around fifteen seconds or even more. Here's the console output from pressing the keyboard shortcut until the kernel's sleep message:
7/31/11 11:50:59 PM mDNSResponder[17]   Client application bug: DNSServiceResolve(charon._smb._tcp.local.) active for over two minutes. This places considerable burden on the network.
7/31/11 11:50:59 PM mDNSResponder[17]   Client application bug: DNSServiceResolve(Meredith(SSH)._ssh._tcp.local.) active for over two minutes. This places considerable burden on the network.
7/31/11 11:51:03 PM kernel  PM notification timeout (pid 3715, Google Chrome He)
7/31/11 11:51:03 PM kernel  hibernate image path: /var/vm/sleepimage
7/31/11 11:51:03 PM kernel  sizeof(IOHibernateImageHeader) == 512
7/31/11 11:51:03 PM kernel  Opened file /var/vm/sleepimage, size 8589934592, partition base 0xc805000, maxio 400000 ssd 1
7/31/11 11:51:03 PM kernel  hibernate image major 14, minor 2, blocksize 512, pollers 5
7/31/11 11:51:03 PM kernel  hibernate_alloc_pages flags 00000000, gobbling 0 pages
7/31/11 11:51:03 PM kernel  hibernate_setup(0) took 0 ms
7/31/11 11:51:06 PM kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
7/31/11 11:51:06 PM kernel  System SafeSleep
7/31/11 11:51:15 PM kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0x00000000
7/31/11 11:51:15 PM kernel  hibernate_page_list_setall start 0xffffff809225b000, 0xffffff809229b000
7/31/11 11:51:15 PM kernel  hibernate_page_list_setall time: 447 ms
7/31/11 11:51:15 PM kernel  pages 1564968, wire 250981, act 375476, inact 548, spec 267, zf 6140, throt 0, could discard act 115301 inact 538951 purgeable 39710 spec 237594
7/31/11 11:51:15 PM kernel  hibernate_page_list_setall found pageCount 633412
7/31/11 11:51:15 PM kernel  IOHibernatePollerOpen, ml_get_interrupts_enabled 0
7/31/11 11:51:15 PM kernel  IOHibernatePollerOpen(0)
7/31/11 11:51:15 PM kernel  writing 631584 pages
7/31/11 11:51:15 PM kernel  encryptStart 69aa50
7/31/11 11:51:15 PM kernel  encryptEnd 89ade70
7/31/11 11:51:15 PM kernel  image1Size 310265344, encryptStart1 69aa50, End1 89ade70
7/31/11 11:51:15 PM kernel  encryptStart 127e4600
7/31/11 11:51:15 PM kernel  encryptEnd 40c9f7c0
7/31/11 11:51:15 PM kernel  PMStats: Hibernate write took 8066 ms
7/31/11 11:51:15 PM kernel  all time: 8066 ms, comp time: 2645 ms, deco time: 0 ms,
7/31/11 11:51:15 PM kernel  image 1086978048, uncompressed 2587336704 (631674), compressed 1074427632 (41%), sum1 4849c5df, sum2 d1708974
7/31/11 11:51:15 PM kernel  wired_pages_encrypted 146094, wired_pages_clear 103149, dirty_pages_encrypted 382431
7/31/11 11:51:15 PM kernel  hibernate_write_image done(0)
7/31/11 11:51:15 PM kernel  sleep

Note that I am aware of this question, but I haven't changed anything in the system and it used to go to sleep faster than now. Considering that PMStats reports a hibernation write time of over eight seconds, this leads me into thinking it is the RAM content.
The only system changes I remember are installing the two updates for 10.6 that came out just before Lion's final release. Did that change anything?
How would I go about troubleshooting this?

Even after
sudo pmset -a hibernatemode 0
sudo pmset -a hibernatemode 1

it takes roughly the same time to sleep.

FYI, here's the information from a "clean" (non-safe) sleep:
8/1/11 2:26:49 PM   kernel  AirPort: Link Down on en1. Reason 8 (Disassociated because station leaving).
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0x00000000
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
8/1/11 2:26:50 PM   configd[14] network configuration changed.
8/1/11 2:26:50 PM   kernel  System Sleep
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0x00000000
8/1/11 2:26:50 PM   configd[14] network configuration changed.
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
8/1/11 2:26:50 PM   configd[14] setting hostname to "charon.local"
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
8/1/11 2:26:50 PM   kernel  IOThunderboltSwitch::i2cWriteDWord - status = 0xe00002ed
8/1/11 2:26:58 PM   kernel  Wake reason = EHC2
8/1/11 2:26:58 PM   kernel  System Wake

Comment: Have you tried a reboot after `pmset` to ensure the writing a sleepimage change takes effect? For most, waiting for 8g of ram contents to sync to disk causes the delay. Do post the system.log messages for a non safe sleep timings as well - might help
Comment: I updated it. Having 45GB available and never taking more space than that, it doesn't seem like a performance thing (haven't had performance issues with the SSD yet). I think 5GB of memory were in use though.
Comment: This is relevant: http://apple.stackexchange.com/questions/56432/chrome-prevents-sleeping
Answer:
Considering that PMStats reports a hibernation write time of over eight seconds, this leads me into thinking it is the RAM content.

Exactly. Your RAM contents are written to the disk, in the default sleep mode, called "Safe sleep", which takes longer the more RAM you have. You can modify this with the PMSet command in terminal.
sudo pmset -a hibernatemode 0

and then reboot.
If you disable this option, you can also remove the sleepimage file from /var/vm, and reclaim 8GB of hard disk space. Do note that you will lose data then if you sleep for too long and the battery dies.
Comment: Odd, did you reboot? And did you delete the sleep image?
If you run `pmset -g | grep hibernate mode`, does it show 0? There's also that "smart sleep" app.
Comment: It should be `grep hibernatemode`, but it is set to 1 anyway. No sleep image to be found. I'll try rebooting now.
Comment: `sudo pmset -a hibernatemode 0` (as suggested in the other question) did not change anything though. Still the same sleep times (about 15 seconds).
Comment: Removing the sleep image won't likely help other than th be sure it didn't get recreated after the reboot ( an indirect way of making sure pmset worked)
Comment: Now (after the reboot) it worked -- still I'm a bit confused. Why didn't it take that long in the beginning? Some setting must have changed.
Comment: Either your SSD has less free space and can't write 8G of files cleanly or your ram has more interesting things in it now. Yu also could have more apps that do things in anticipation of a sleep event. Your mac just might have more to clean up.
Answer: I used to have an episode of slow boot, shutdown, sleep and hibernate. When I turn on verbose mode during boot-up, it was stuck at "Waiting for DSMOS" for a long time. See this link. To solve it, see this link.
Thereafter, all my slow-downs were gone.
Comment: Shutting down and booting is fine actually, it's only the safe sleep that's being slow. Thanks though, I'll read through it!
Answer: Do you by any chance have a firewire device plugged in? If I try to sleep my Macpro (tower) with an older iSight camera plugged in via Firewire, it takes 10-20 seconds to sleep, vs the normal 2-3.
Comment: For me that wasn't the case, but good to know!


Why do we only feel the centrifugal force?

Question: After spending some time researching about the centrifugal force, I now understand that it is needed in a non-inertial reference frame for Newton's Laws to hold true. However, I don't understand why we only feel the centrifugal force when moving in a circular path. For example, if you imagine yourself being spun around in a circle, then in your frame of reference you would feel yourself being pushed outwards. But since in your frame of reference you are stationary, the outwards force must be balanced by an inward pull (for you to remain stationary). So why would you only feel the outwards force but not the inwards force?
Answer: Suppose you have your feet pointing outwards and your head pointing towards the centre of rotation:

Now ask your self what direction the force you feel is pointing. Well, the force is pushing upwards on your feet, so the force points from your feet towards your head. In other words the force you feel is pointing inwards not outwards i.e. it is the centripetal force.
Comment: @BlurryPic: exactly, though strictly speaking you don't move towards the side of the car. You're trying to move in a  straight line, and it's the side of the car that moves (accelerates) towards you.
Comment: Would this also be the case when driving around a bend? ie. the force from the side of the car provides the centripetal force, but the reason you "move" towards the side of the car is because of your inertia?
Comment: I did not get the force direction, because when a person is standing inside the box, it will have the environment just like the earth so the force should act away from the pivot direction. I think the centripetal acceleration is for the object in the circular motion and centrifugal force is the reaction force on the object in side the box. Don't you think @JohnRennie?
Answer: When you are standing upright imagine a downward external force on your head and an equal magnitude upward force on your feet.
These two forces will compress you and you "feel" being compressed as a result of these two forces acting on you.
Imagine that you are being spun round in an apparatus as shown in @JohnRennie 's diagram.
In his example there is an external force on you due to the "floor".
In order for all parts of your body to have an inward force so as to rotate your body must be compressed.
So you "feel" compressed and interpret this as being acted upon by two forces one of which is real and causing the centripetal acceleration, the force of the the floor on you, and another force which is not real, an outward force which is supposedly helping to compress you - a centrifugal force.


Adding additional labels to arrows

Question: Is it possible to add additional labels to an arrow, like the relational arrows have multiple text fields?
Answer: This is now possible by simplying clicking on an arrow and start typing.
Comment: Cool thanks. Although it would be more first time intuitive to double click the line and seeing a box with a cursor so user knows you can type just like LucidChart does.
Answer: Not currently, but you're welcome to add it as a feature request.
Answer: I haven't found a way to add a label to an existing arrow, but I did find a way to create labeled arrows using one of the built-in UML shapes.

First, locate the set of UML shapes at the left panel. It is listed by default (if you cannot find it, click on "More shapes..." and make sure that "UML" is enabled). Among the 24 UML shapes, there are several kinds of arrow/label combinations. For example, if you want to get a line with a label, choose "Generalization" shape.

Drag the generalization arrow to your painting. The result will be a line with two endpoints and a text label with an orange dot. This orange dot is the anchor of the label, if you move the arrow, the anchor and the text will move along.

If you want to style the arrow differently, just click on the arrowhead icon in the toolbar and select a different arrowhead. E.g. if you want to remove the arrowhead, pick the top option ("None").

The label text can be changed by clicking on the label. It can even be moved by moving the orange dot around. The label will still be positioned relative to the arrow.

The appearance of the line can be customized as well. The format menu allows you to change the line width, line style (dashed / dotted / solid / ... ), color and many other properties.

Adding additional labels to arrows


Are there bidirectional neurons?

Question: Neurons are mostly unidirectional, i.e. electrical impulses enter from one end and leave through the other. Are there bidirectional neurons as well, i.e., neurons that have a receiving end and a transmitting end that are not mutually exclusive?
Answer: Chemical synapses can be bidirectional, especially in invertebrates:
https://www.ncbi.nlm.nih.gov/pubmed/2984356
https://elifesciences.org/articles/16962
Answer: The classical, chemical synapse offers only one-way traffic. Under physiological conditions, the presynaptic neuron releases vesicles at its axon terminal and the postsynaptic neuron expresses the corresponding receptor proteins in the dendritic region. Conversely, the presynaptic neuron lacks the receptor molecules and the postsynaptic neuron lacks the secretory machinery to release neurotransmitter into the synaptic cleft (Purves et al., 2001).
Note, however, that the presynaptic neuron may express regulatory neurotransmitter receptors that bind its own released neurotransmitter, but these do not generate action potentials. And note that the postsynaptic neuron may release neuromodulators in the synaptic cleft. However, these compounds do not initiate action potentials, but have only a regulatory role.
There is, however, also the electrical synapse, mediated by gap junctions. These gap junctions are protein pores that electrically and chemically connect adjacent neurons directly. In this case, potential changes generated in one cell may freely spread like a wave to other neighboring cells. Note that this mode of electric coupling does not induce action potentials, but it represents the passive spread of voltage differences, called electrotonic coupling (Mylvaganam et al., 2014). Which cell initiates the wave is irrelevant, as the wave can spread to each cell as long as it is connection via gap junctions. Although these gap junctions are referred to as electrical synapses, the terminology presynaptic and postsynaptic applies in a much looser sense, as any neuron in the tissue can act as either one (Sheriar, 2004).
References
- Mylvaganam et al., Front Physiol (2014); 5: 172
- Purves et al. (eds.), Neuroscience. 2nd ed. Sunderland (MA): Sinauer Associates (2001)
- Sherair BBA (2004); 1662(1–2): 113–37
Comment: So antidromically moving action potentials in the sense of neural backpropagation (and not electrotonic potentials) can be effected by electrical synapse activity?
Comment: Great @Christiaan, thanks for the detail on gap junction location. Am I wrong that there would rather be electrotonic potentials rather than action potentials then?
Comment: @huh I'm unsure if antidromic action potentials occur *in vivo*. Gap junctions are, afaik, situated at the soma. .
Comment: @huh - in fact you are spot on. Thanks for that. I've adapted my answer.
Comment: In the cerebellar cortex there are Golgi cells with dendrodendritic gap junctions, important in the organization of their neural oscillation.

Are there bidirectional neurons?


Is Ludociel the fastest character in Nanatsu no Taizai?

Question: So the archangel Ludociel was given the grace "flash" by the Supreme Deity. It's said he can move almost instantly. Does this make him the fastest character in the series? Or do characters like Meliodas or Ban who have been shown to be very fast compete with his speed?
Answer: We do not know the upper limits of Flash, neither do we know how it fares against other quick characters.
There have been no satisfying points of comparison between Ludociel and other extremely quick characters. The wiki only notes that "[it] allows Ludociel to move at immense speeds which appears as a form of teleportation." which is consistent with Flash's depiction within the series. Both Derrierie and Escanor, two experienced fighters ranking among the strongest characters in the series, were completely unable to follow Ludociel's movements.
Flash, generally speaking, has been scarcely used and is thus hard to describe and quantify. If we try to understand its inner workings by comparing it to other angelic Graces, we can infer its strength directly stems from the natural element of light (it could be lightning thematically, but we have seen numerous weaker characters reacting to and dodging lightning). Both Ocean (from Sariel) and Tornado (from Tarmiel) have demonstrated the ability to create a pocket universe almost exclusively containing their own element (manifesting as a windy ocean when they combine their abilities).
The best explanation we can try to offer for Flash is that it is a light-based Grace allowing Ludociel to literally move at the speed of light, thus explaining his extreme unmatched speed. If this theory is true, it is very unlikely other characters could possibly match him in a speed contest.


Unable to remove hard turmeric stains on the apartment common carpet

Question: We just moved in to a new apartment and spilled some turmeric over the common carpet area in front of our main door. Tried treating the stains with stain remover, bleach and dishwashing liquid and so forth and so on. No luck with anything. Could anyone please suggest how to remove a week old hard turmeric stains on a colored carpet.
Comment: how is this a home improvement question?
Comment: @jsotola - Where do you think this question will fit in the stack exchange communities?
Answer: Tumeric is the most colorful component of curry. Good luck, tumeric can be used as a fabric dye. It doesn't come out of nice Brooks Brothers white shirts.
Good Housekeeping suggests the following for curry stains in carpet:

Carpet

Mix one tablespoon of liquid hand dishwashing detergent and one tablespoon of white vinegar with two cups of warm water.
Using a clean white cloth, sponge the stain with the detergent/vinegar solution. Blot frequently with a dry cloth until the stain disappears.
Sponge with plain water; blot until the liquid is absorbed.
Sponge the stain with rubbing alcohol; blot to remove the stain.
Sponge with water; blot until the liquid is absorbed.
If the stain remains, mix one teaspoon of liquid hand dishwashing detergent and one tablespoon of ammonia with two cups of warm water.
Sponge the stain with the detergent/ammonia solution. Leave it on the stain for at least 30 minutes, blotting every five minutes with a clean white cloth and more solution.
Sponge with cold water and blot dry.

Personally, I would try it in an inconspicuous portion of carpet first in case it makes things worse in some way.
Comment: Thank you for the tips. Will try them in order and let you know the result.


How to choose right shard key for MongoDB

Question: My document structure is:
<code>"_id": ObjectId("50c41fae0e708237dc7a5187"),
"uid": "999",
"appname": "authentication",
"activityId": "login",
"activityName": "login",
"date": ISODate("2012-12-09T05: 20: 46.117Z"),
"yearmonth": "201212"
</code>
uid is userid generated by other application from RDMS sequences.
yearmonth is artificial field I have created in the apps only for the purpose of better shard key.
Write pattern:
As user login or perform specific action on a site, I write event into mongoDB. This means uid is relatively random with very high cardinality.
For the same uid I can write hundreds of events.
Read pattern:
Most queries are based on uid as a first query parameter. {uid:"9999",date:{$gt: ....}, activityId:'login'}
My initial shard key was  {uid:1, date:1}. -  to provide a good query isolation and have splittable chunks if any one uid has too many documents.
Now, based on How to choose a shard key: the card game article and some webinar and comments on this forum I realize that better key should be something with
{coarse timestamp:1 , search criteria:1} . Idea is to have better locality for the shard key to help with write performance.
so I have created yearmonth field and thinking about changing my shard key to {yearmonth:1, uid:1}
The question is:
Do I loose query isolation and performance of read operation because of the change?
My query parameter will not match first element of the shard key anymore.
Comment: I asked a similar question: http://stackoverflow.com/questions/14798590/finding-a-good-index-and-shard-key-in-mongodb
Answer: I would just stick with uid as that is the key you are going to use to fetch the data.
Shard key - uid
Especially when it is a random uid based event insert and read, it would be very optimal to keep the uid as the shard key.
When the chunks grow bigger, the Balancer in the MongoDB is going to automatically balance the chunks across different shard servers.  So you are covered here as well (as the automatic balance will take care of some shard server growing too bigger).
Hope this helps.


What does the key of a song mean?

Question: I want to know what it means, in terms of the scales and chords involved, when we say that a song is played in a certain 'key'.
Answer: A key is simply telling you the note that will be perceived as tonic (you'll sound at rest on that note) and the expected harmony and melody.
For example, when someone tells you a song is in the key of C major you can expect a majority of the song to use notes from the C major scale and use chords built from the C major scale and the harmony and melody constructed will want to go to C. There are almost always other chords and scales that are used, but they will still have the goal of making C sound like the tonic unless you modulate which means change keys.
When someone tells you a song is in the key of C minor you can expect a majority of the song to use notes of the C minor scale and use chords built from the C minor scale and the harmony and melody constructed will want to go to C. It's the same idea as above, just now we are using ideas from C minor to base the melody and harmony on.
Answer: Said another way, when we speak of a musical key we are referring to a much larger concept than just a scale or a "key" note (tonic).  Of course, a musical key includes a tonic and a scale (mode), but the psychological magic of a musical key is not found in memorizing scales and chords, it is found in discovering the family relationships between all the constituent parts of a chosen "key."  For example, the harmonic qualities of chords, chord changes, intervallic movement in melody, and predictable tonal behaviors used in improvisation are all implied by the key.
A musical key describes a context for music; it is a structural system that creates meaning for any given note or set of notes used in the music--a palette of related tonal materials used for emotional communication. Using a musical key creates a context in which to measure movement, to create the sense of a musical journey, a point of departure for materials that are not in the key, and a sense of coming home at the completion of a journey. It is this movement within a specified key that creates emotional communication and connection.
A musical key can also be figured as a solar system of sorts where the tonic (key note) is the gravitational center of the key.  The tones supplied by the scale are the building blocks for melody and harmony/chords within the key, where each tonal degree of the scale occupies a fixed intervallic distance away from the key center.
When you understand the cosmos of the key, you understand how the movement of melodic tones, intervals, scale tones, chord tones relate and behave with each other.
Melodic tones travel in various tension and release movements in relation to their distance from the key note.  Melodic tones are derived from the scale of the key and live inside of chords.
Chords are little subsystems inside the larger key and have their own tonal centers inside the smaller chord structure. Each voice in the chord orbits around the central chord tone (chord root), while each chord system has an orbital relationship to the larger key center (tonic).
A key is the tonality that is central to a piece of music. What that means is that a key is based on a tone and a structure built around that tone.  It is this structure that provides context and meaning inside the music.
Comment: Special thanks, I learned a lot, almost everything about harmony. brilliant!!!
Comment: What a beautiful answer.
Answer: The key of a song is usually indicated at the beginning of the sheet music. As in C major,(or A minor) which has only 'ordinary' notes - no sharps or flats - will have nothing at the beginning, whereas Eb (or C minor) will have 3 flats indicated at the beginning of each line, because that key will usually use 'ordinary' or natural notes, with the exception of Bb, Eb and Ab.
As Dom points out, there will be a 'home' note and chord that a specific key gravitates to, and that's the name the key takes on. Scales are just those special notes from a specific key, put into order, and will be the mainstay of notes contained in most tunes in that key.
Since chords are made up from the notes in the scale, thus the key, they will generally contain three or more notes from that scale, and usually be used under some of the notes contained in the chord played in that bar.
Answer: AS Dom almost said the key of a piece is a psychological effect. Being "tonic" and "sound at rest on that note" are alluding to the fundamental concept as being a psychological reaction. Key signatures clearly are not adequate since they each have two keys. Also there is no definite relationship between the notes played and the musical key. There are scales and chords which are generally believed to have this psychological effect but they are not required to be used to be in a particular key.
If anyone knows of any experimental studies quantifying this effect I'd love to hear about them.
Answer: The piano has twelve keys per octave.
If you count from any one note to an octave higher or lower, and include all the keys (black ones and white ones) then you shall find there are twelve per octave, but only a subset of them are used when playing a song.
This subset is called the key.

What does the key of a song mean?


Video encoding for mobile: How do I choose FPS and bit rate?

Question: I'm going to encode a video from DVD to mobile supported format (mp4, flv, H.263). For a 320x240 screen if I choose around 600 kb/s, how would I know FPS that I want? How is the bitrate is related to FPS?
Answer: They are not related.
FPS means how many unique frames are displayed per second on the device. Lower FPS will result in a jerky video. Higher FPS will result in a smoother video. On my Sony Ericsson W595 phone I set it to 15. You can set it higher (25) if you have a high end phone.
Bit rate means the size of a second of video in kilobits. More size = more details. Higher bit rate will look better but consume more processing power. Larger resolutions at high bit rates look good. For mobile devices, 600 kBit/s is sufficient.
Answer: For a mobile phone, you need to check your manufacturer's recommended settings.  There's a lot more to consider other then frame rate and bit rate (e.g. most embedded devices cannot play back videos with B-frames).  If the device supports it, try to keep the frame rate the same as the source material.
If you're not sure what settings to use, there are plenty of guides on the internet.  Alternatively, you can try to use some of the profiles bundled with a video encoding program (e.g. MeGUI or HandBrake).

Frame rate is not dictated at all by bit rate, but higher frame rates at the same bit rate will result in a lower quality video (there are more frames to compress into the same amount of disk space).  I wouldn't worry too much about the frame rate (again, choose as close to the source material as you can), but too high of a bit rate may cause problems with mobile devices.
Answer: You are going to want whatever the FPS is of the DVD you are encoding from unless you are trying to telecine (which may be necessary if your mobile device wants video in specific frames/sec). The only relation between bitrate and FPS is roughly how many bits get used ON AVERAGE to encode each frame. For example, if you have a 25FPS DVD for PAL, you're spending on average 24kbits per frame.


Schengen visa, insurance, flight refunds after cancellation because of COVID-19

Question: I just had my Schengen visa appointment this morning in the UK and paid 300 pounds for my Schengen fees, Swisscare Schengen insurance, and roundtrip nonrefundable flight tickets with Swiss Air. However, as I am a exchange student from the U.S., my U.S. university just this afternoon(hours after my morning appointment) announced that all exchange students needed to return back to the U.S. immediately due to the recent coronavirus outbreak. I am wondering if I can get any refunds for what I have already paid?
Answer: Insurance premium
You can cancel the insurance at any time before the coverage begins.  The company website says

Before the beginning of coverage, ... you can request a full refund at any time.

Visa application fee
Your visa fee is probably lost, but you might try asking if you can adjust your application dates.  I wouldn't hold my breath.
Air fare
Rebooking
Subject to some conditions, you can probably rebook the air tickets without change fees:

SWISS will waive its rebooking fees for all newly booked flights worldwide with immediate effect and until March 31 and offer a one-off free rebooking. For existing bookings, the new waiver policy will apply worldwide to all flights booked by March 5 with a departure date up to April 30, 2020. Passengers will thus be able to rebook their flight ticket once to a new date up to December 31, 2020 without incurring any rebooking fee.

As noted by Mark Johnson in a comment, this policy applies to the entire Lufthansa Group.
Refund
If you're lucky enough that your flight is cancelled, however, you might get a refund:

For cancelled flights: If you have booked through swiss.com or a Service Centre and you don't want to rebook your flight ticket, you can refund your ticket. To do so, please complete the refund form.
If you booked through an (online) travel agency, please contact the travel agency.

I say "might" because I don't know whether you'd be able to get a refund if the flight is cancelled after you rebook it.
Taxes and fees
Even if you cannot recover your airfare, you should be entitled to a refund of certain taxes and fees for flights that you didn't actually take.
Possible insurance claims
If you have any travel insurance or other general insurance, you may want to look at whether it would cover any losses you incur.  Again, I wouldn't hold my breath, but it's better to check now rather than to find out after the claim deadline has passed that you might have been eligible for reimbursement.  (The Swisscare Schengen insurance seems not to include trip cancellation coverage, but I did not look very closely.)
Comment: This is, I believe, true for all the airlines in the [Lufthansa Group](https://www.lufthansa.com/de/de/lufthansa-group-star-alliance-und-partner-airlines)
Comment: @MarkJohnson yes, that is true.  The paragraph before the first one quoted in this answer says explicitly that the policy "is valid for flights of all Lufthansa Group airlines."


Frozen discard pile

Question: When picking up a frozen discard pile I understand that you have to have a natural pair in your hand, but can I add those cards to a meld in play in front of me to create a canasta?
Answer: Yes, once you have picked up the discard pile, the cards are all in your hand like normal; and you can always add to any existing meld by melding more cards from your hand. Whether the discard pile was frozen or not does not have any relevance here.

A player may add additional cards to a meld by his side, provided that the melds remain valid (having no more than three wild cards). He may not add cards to the opponents' melds.

https://www.bicyclecards.com/how-to-play/canasta/
Comment: You're welcome. On Stack Exchange; the best way to thank someone is to vote the answer up if you found it useful, and click the check to accept it if it's the best one. Sometimes it's useful to wait a little bit before accepting an answer to see if other people answer as well.

Frozen discard pile


Rayleigh scattering from the moon light

Question: If the moon reflects exactly the sun spectrum, then the blue photons part of the spectrum should scatter in the atmosphere during the night (assuming a perfect dark night sky). Why don't we see a bluish light during the night, the equivalent of a blue sky during the day ?
Comment: This is answers on Physics.SE: http://physics.stackexchange.com/questions/15184/why-is-moonlight-less-colourful-than-yellow-light
Comment: Why would we expect the moon to reflect exactly the sun's spectrum?
Answer: Answer to this question is very well given at Physics forum pointed out by @gerrit. In short, Light should be strong enough in order to notice its colour by human eyes. Even on full moon night, light from the moon is 10 times less luminous than the dark limit of civil twilight hence we don't perceive sky color or even moon colour like we do during the day.

Rayleigh scattering from the moon light


Why when I add jam to my tea it stops producing thin "membrane" on top?

Question: Thin "membrane" is created if I leave cup of tea for hour or more. And it usually sticks to the inner sides of the cup. But I noticed that when I drink tea with jam or syrup then the cup always clean inside as if the syrup contains some kind of acid that remove that tea-thingy.
Comment: I suspect your tap water is pretty hard and this layer is floating limescale particles.
Comment: @andselisk looks like I've found the answer https://cooking.stackexchange.com/a/78500. You was right, it is all about hard water
Comment: @andselisk It happens with my cup of tea too, only that I don't add water, boil the milk, and add the tea leaves.
Comment: Hold on, so you observe a similarly looking "membrane" on top of just milk (no water)? Or you add milk to the tea? Also, a photo might help.
Comment: @andselisk but this layer emerge only in tea. It smells like tea, it has similar color. Also I was sure that everyone saw it :/
Comment: So, you make a tea from milk and tea leaves (no extra water) and the layer is there? I saw this limescale layer where people with hard water supply don't use reverse osmosis, that's it.
Comment: Well, even though you haven't answered half of my questions, since you figured it out, I suggest you can answer your own question: feel free to start with my comment then:).
Comment: Are you sure that it is not milk fat?
Answer: The parallel process to deposition of limescale ( that is inhibited by acidic jam) is deposition of products of oxidation of epigallocatechine gallate(EGCG) and similar compounds, that are getting adsorbed on limescale particles and cup walls.

Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin.
It is found in high content in the dried leaves of green tea (7380 mg per 100 g), white tea(4245 mg per 100 g), and in smaller quantities, black tea (936 mg per 100 g).During black tea production, the catechins are mostly converted to theaflavins and thearubigins via polyphenol oxidases.

EGCG is a polyphenol, vulnerable to oxidation on neutral/alkalic environment, forming insoluble product of intense brown color.
Acidic environment, caused by addition of jam or lemon juice, stabilizes the compound.
Minor natural content of ascorbic acid in fruit juice is protected by abundance of organic acids by similar way.
Comment: "It does similar thing to ascorbic acid" Do you mean "It does a similar thing as ascorbic acid [does]"/"It does a thing similar to what ascorbic acid does"?
Comment: No. I mean high abundance of organic acids ( citric, tartaric, acetic, malleic ) protects oxidation of minor ascorbic acid, that gets oxidized much slowly in acidic environment. OTOH, if ascorbic acid gets alkalized, it quickly oxidizes by oxygen, turning quite clear solution to intense yellow. But of course, abundance of ascorbic acid would protect EGCG as well.
Answer: As @andselisk suggested the problem lied in hard water. And calling that thingy "layer" instead of "membrane" helped to google the problem properly: cooking.stackexchange.com >, www.teamuse.com >
"The scum on the top of the tea is due to hard water (ie calcium carbonate) deposits combining with the tea and reacting with oxygen."
To dissolve that layer we need to rise acid level: add lemon, jam, syrup or even make stronger tea.


Redirected to unsafe page on freshly installed Windows 10

Question: This is my first question in security, so let me know if something about the question should be fixed.
Some background information:
My Windows 10 laptop was starting to get realy, realy slow when browsing the internet (Chrome lagged alot when fetching simple pages like www.google.com). However i could still play rather demanding games without too much trouble. A week ago i got a call from my internet provider telling me a unit was sending spam-emails from the IP of my appartement.
To try to fix this, i ran a full AVG-scan on both my Windows 10 units (nothing was found). I also had a raspberry pi, open for SSH-Connections with default username and password (very bad practise, i know) which i turned off and disconnected.
My guess was that is was the PI that was responsible for the spam-emails. But since my main laptop was much slower than it should be, i did a fresh install of Windows 10 today, through a bootable USB.
Now to my problem:
The first thing i did, on the new Windows 10, was to open edge and type www.google.com, but i got no response, just a blank page, tried closing Edge and redo, same issue. Then i tried Internet Explorer and i typed in www.google.se, and i somehow ended up at a "There are hot womens in your neighbourhood"-site (the domain ended in rsc.cdn77.org).
My question:
What can be the reason i was redirected to that page on a freshly installed Windows 10 and should i still be worried? Can my router be infected (its a standard router from my internet provider on which i could not lockate the DNS on)? Can another unit on my WiFi be infected and cause this (the only other units connected was two Android phones, a TiVo and a couple of chromecasts according too me and according too the status page on my router)?
Comment: Did you get the software from the bootable USB from somewhere reliable (such as Microsoft)?  If not, I would suspect that the new install of Windows came with viruses pre-loaded.
Comment: It came from Microsoft.
Answer: It sounds like your router has been infected by a dns hijacking malware.
Comment: It depends on the malware and the router but you might want to give it a try
Comment: Can that be fixed by simply resetting the router (i.e. pressing the reset button at the back)? Or can it be infected at a deeper level?


Can I use "Donald Trump" in my brand name?

Question: I am creating an apparel brand and want to use the words "Donald Trump" in the company name. Is this illegal? I will be selling political apparel.
Answer: If you are Donald Trump posting under an assumed name then it is illegal, because he is currently president of the USA and not supposed to run any businesses.
If you are not Donald Trump, then be aware that Donald Trump owns a trademark for "Donald Trump" according to this site https://onlinetrademarkattorneys.com/donald-trump-trademarks/ so you will be infringing on his trademark.
Comment: (1) Are you sure it is *illegal* for the President to run a business?  I'm not aware of any law that forbids it, though it has not been customary for presidents to do so and there is strong political pressure against it.  The limitations on outside income from the 1978 Ethics in Government Act (5 USC 501-505) apparently do not apply to the President (the definition of "officer or employee" in 5 USC 505 references 18 USC 202, where paragraph (c) explicitly excludes the President).
Comment: (2) It's my understanding that trademarks apply to a specific type of good or service.  So the question would be whether Trump owns a trademark for "Donald Trump" as used to market clothing or some related product.  He doesn't and can't have a blanket trademark on all uses.  Incidentally, someone named Mark Wallis was granted trademark #87956983 for "Donald Trump Barf Bag".
Comment: So in essence, it is illegal to use the words "Donald Trump" in my company name even if another word comes after it? (Just to be clear)

Thank you!
Answer: A trademark is for a specific kind of thing. That's why, in his commercials, Bill Cosby keeps saying "Jell-O Brand Gelatin."
On a trademark application, you must list the Goods or Services for which the proposed trademark will be used.
"You may clarify or limit the goods/services but you may not expand or broaden the goods/services. For example, if you filed for "shirts," you may limit the goods to specific types of shirts such as "t-shirts and sweatshirts." However, you may not change the goods to "pants." Likewise, if you file for "jewelry," you may change the goods to specific types of jewelry such as "jewelry, namely, earrings." However, you may not change the goods to a service such as "jewelry stores.""
https://www.uspto.gov/sites/default/files/documents/BasicFacts.pdf
It appears to me that as long as you don't use the name "Donald Trump" for the same goods/services that his copyright is for, there is no infringement. But if I were you, I would go ahead and apply for a trademark of your own. If the USPTO approves your trademark application for "Donald Trump Apparel" (or whatever) then you'll be way ahead of the game.
See also: https://www.uspto.gov/trademarks-getting-started/trademark-basics


How to calculate center of mass with a prismatic joint

Question: Suppose we a 1DoF planar robot with only 1 prismatic joint  (for the sake of the example).
The prismatic joint can extend the link or shrink the link.
Suppose the length of link 1 is a, and suppose the center of mass is in the middle of the link.
Let d be the ony generalized variable.
My doubt is: the center of mass is (a/2)+d or (a+d)/2  (w.r.t. the frame placed in the joint) ?
Answer: You have rigid parts that can move independently (subject to the degree-of-freedom constraint). Each part has its own center of mass. The overall CoM is the mean of the part CoM's, expressed in a common Cartesian coordinate system, weighted (pun unavoidable) by their respective mass fraction.
That should be general enough to compute the overall CoM for any number of parts with any number of generalized coords.


Why is the rice in my mushroom risotto always very hard?

Question: I'm a fan of Italian mushroom risotto and I love to cook it from time to time, but cooking the arborio rice well seems impossible to me if I follow  traditional recipes. Last time I pre-cooked the rice in water before boiling it in cooking wine but this didn't seem to help. No matter for how long I boil it, I end up with very hard rice at the end. Does anyone know the best way to cook risotto to avoid this?
Comment: Boil risotto? I've always simmered slowly, adding stock a ladle at a time till the rice was just before the texture I wanted. Allowing for it to carry on cooking between pan and table. The key is to 'fry' the rice in butter till it turns transparent.
Comment: How long is *"No matter for how long I boil it"*?
Comment: @Stephie There is this, and to this day I have not figured it out. http://cooking.stackexchange.com/questions/44847/why-would-a-rice-seem-non-absorbent I've even bought that brand again and not had a problem. Weird.
Comment: @Doug You mention a better way to say what I was trying to say in my answer. Edited.
Comment: Glad I could be of assistance :-)
Comment: You don't boil risotto rice, you fry it and then simmer it in the cooking liquid (usually wine and broth).
Comment: possible duplicate : http://cooking.stackexchange.com/q/6391/67 or http://cooking.stackexchange.com/q/54/67
Answer: I love risotto. A few things might help.

Use a saucepan, not a skillet. I had never really noticed a difference until ElendilTheTall (another user here) pointed it out. It makes a big difference. So you should have 2 sauce pans on the stove, one for your simmering broth, one for the rice.
Brown your aromatics and your mushrooms well in butter and oil and include your dry rice. The rice should get quite translucent before you add wine to the pan. The wine should sizzle and boil dramatically.
The old idea that you need to stir constantly is silly. Add your broth a big ladleful at a time (you can add larger amounts of broth for the first couple of additions), keep the heat high enough that it maintains a low boil and keep an eye on it, stirring occasionally. Add more broth well before the rice seems dry.
Each batch will vary regarding exactly how long it will take and how much broth it will need, so be prepared for today's batch to take longer and need more broth that last week's batch, even if everything seems the same. But shouldn't take more than about a half an hour as long as you've kept it at a low boil (high simmer?) and haven't let it dry out.

That's it. Add Parmesan when the rice is done, and true arborio is worth it.
EDIT: Oh and BTW, cooking wine is nasty. Use real wine, your rice may just be insulted by "cooking wine". For "cooking wine" they add huge amounts of salt to bad wine to make it undrinkable, so that they can legally put it on grocery store shelves and sell it to minors.
Comment: you should see the stove and pans I have at work... Sometimes I feel I'd be better off with an open fire and bean can...
Comment: Stirring constantly is something left over from the inconsistent heat source and crap pan era, to stop the rice sticking to your pan and burning, tainting your food in the process (like with a bechemel). Still a good idea if you have cheap thin bottomed pans if you ask me.
Comment: @Doug Certainly if you have crappy pans and a cheap stove! :) Which, of course, some of us do. Ah, college days.


Can I use an air compressor to change car tires?

Question: Is a 100 psi oil-less air compressor powerful enough to enable an air drill to remove and tighten lug nuts when changing car tires?
Comment: When you say "change car tires" what exactly are you trying to accomplish? Taking the wheel/tire off of the car, or taking the tire off of the wheel? What tools were you going to use to accomplish this? Are you just talking about refilling the tire after it's reseated onto the rim? Need some more information.
Comment: Yes Paulster2 I would like to be able to take the tire/ wheel off the car, like if I have to put the donut on for some reason. I do not currently have any tools this is for just in case purposes.
Comment: While it may be powerful enough, you'll never know how tight you have fastened it. Use a torque wrench and respect the torque limits that the manufacturer gives. If you don't have one, you better fasten it by hand instead of an air drill, you have better feeling of how much torque you apply, to tighten all nuts evenly.
Answer: To change a wheel you will need an air wrench, not an air drill - the first two I found with a quick search both specify 90psi, so a 100psi compressor should be more than enough - though it's the flow rate (measured in cfm) that is more important than the max pressure.
Answer: Yes, but you must have an accurate in-line pressure gauge and check it continuously while you hold the tire air chuck in place (do not use a clip-on chuck, as used on foot pumps), or better, a regulator to limit the maximum pressure.
Injuries and even deaths have resulted from over-pressurized tires, particularly during mounting. Smaller tires, such as on bicycles, can be overfilled much more rapidly than car tires... I was present when a friend's bike tire exploded at a service-station pump, and I was unable to hear for minutes afterwards.
Comment: The OP wanted to know about **changing** tires, not **inflating** them.
Comment: The internet wanted this answer instead of the one OP was asking, though. It's appreciated.
Answer: I'll assume you're not really using a drill to change tyres.
Air tools like an impact driver (commonly known as windy-gun) usually require 100psi and a good airflow to achieve the high torque required to undo wheel nuts - on a passenger car it should be no problem, on bigger vehicles (4x4, truck, etc.) you need a LOT more torque and it may not work.
However it is not a good idea to tighten your wheel nuts with that device as it has no torque control. If it has enough power to undo your wheel nuts/studs it probably has too much power to put them back on without over-tightening. If it doesn't have the power to undo the nuts/studs then it will not have the power to tighten them safely.
Tightening by hand, ideally using a torque wrench set to the manufacturer's specification, is the way it should be done. Professional wheel & tyre fitting shops use torque wrenches or other devices (including special air tools) which are calibrated to give a safe amount of torque.
I've seen wheel studs have the threads stripped or alloy wheels be damaged when lazy mechanics put the wheels on using an impact driver.


If airliners and commercial planes have turbulence, can helicopters have turbulence?

Question: I was watching a video of an V 22 (Osprey) taking off and it had that white cloudy stuff that looked like turbulence around the propellers. Can helicopters have turbulence too? I know an osprey is not a full helicopter nor airplane but it has some features of a helicopter.
Comment: I think you are asking about contrails or wingtip vortices, not turbulence. Turbulence is chaotic changes in air pressure which cause bumpiness when flying.
Comment: "white cloudy stuff that looked like turbulence". You can't *see* turbulence!
Answer: That 'cloudy stuff' that you say is not 'turbulence', but condensed water vapor, the condensation being due to the sudden cooling caused by the adiabatic expansion of the air due to the aerodynamic disturbance caused by a passing blade (or wing).
That condensation can also be observed as wakes in landing aircraft, and in stationary revving props. It appears when the sudden expansion takes place in humidity conditions close to saturation.
Comment: But yes, helicopters can experience turbulence just the same as an airplane. ;)
Answer: It's just as possible to get turb on a helicopter as on a fixed-wing aircraft: Turbulence is primarily caused by the characteristics of the air you're flying through, not the machine you're in.
That said, the rotors on a helicopter are reasonably good at damping turbulence (like the wings on an A380). As the V22 has smaller rotors it may be a little more bumpy than other - traditional - helicopters.
Comment: The super simple answer is that the helicopter moves through the air and **with** it.  It the air moves, then the helicopter will too. As to the condensation, [this video](https://www.youtube.com/watch?v=lslarZiRJhg) shows it nicely.


Are some pieces better than others in Blokus?

Question: Obviously the smaller pieces are generally easier to get rid of than the larger pieces, but I'd be interested to know which pieces I should aim to get rid of first, and which pieces I should save.  I'm sure this largely depends on the gaps on the playing board, but are there some pieces that go better in the majority of cases?
Comment: I'm wondering if might make sense to reword the question to better match the question in the longer text. Something like: Which pieces are best to play first in Blokus?
Comment: @JoeGolton I was actually trying not to ask which pieces to play first :-)  I already asked that here: http://boardgames.stackexchange.com/questions/1497/what-is-a-good-opening-in-blokus?rq=1
Comment: I'm even more confused, then. For example, I think the "best piece" by far is the "1." The 1 should be withheld from being played until it affords you an opportunity to break out into an entirely new territory from which you would otherwise be blocked. So that's a good answer to your headline question, but not a good answer to text which asks about "which to get rid of first."
Comment: I agree, the "one" is the best piece and so you shouldn't try to get rid of it
Answer: For scoring purposes alone placing the pentominoes first is the optimal approach.

What you place first depends on your strategy.  Sometimes I like to go straight after another player to attempt to block them in.  Y, I, and L are good opening pieces for that.  For a more balanced to the middle approach, I like to open with F or W.  They give lots of corners to build off of and are not immediately threatening to the other players.
I, P, T and X can be difficult to place later in the game, so I like to get them out as soon as possible.  F, U, L, W and Z are all great for cutting other players off, so I like to save them for when I get close to another color.
Usually only 2 of the 4's give me trouble; the straight piece, and the perfect square. I tend to prioritizing placing them over all the smaller pieces and even some of the 5's.
In most games what you place becomes highly dependent on what the other players are doing.  Especially in later turns.  You need to give yourself room to grow while simultaneously denying space to your opponents.
Answer: Most certainly; all pieces are NOT created equal, some pieces are greater than others.
I've found that the 'better' pieces are the ones with more vertices.  The fewer points a piece has, the easier it is for an opponent to fully block all expansion opportunities.  The more points a piece has, the more opportunities you'll have for branching the next piece off of it.
Accordingly, I try to play my "low-point" pieces early, and in 'unimportant' locations.  I try to save my "high-point" pieces for when I begin encountering the enemy and expect resistance.
To list:
<code>I = 4
P = 5
V = 5
L = 5
N = 6
T = 6
U = 6
Y = 6
Z = 6
F = 7
W = 7
X = 8
</code>
Of course, none of that takes into account how easy or difficult a piece can be to play, merely how strong it can be after it's been played.  Additionally, the situation can make a piece much stronger; the long bars are excellent for making a long jump into enemy territory, and if they can be played to block an opponents expansion into that area then they're the perfect piece for the moment.  In general though, the vertex count gives me a good and easy way to rate pieces.
Answer: Like so many Blokus questions, the answer is: "It depends".
Late in the game, the "best pieces" are the ones you can still play.
That will depend on what your opponents have done already,
and won't always be the same ones.
All the pieces are both "good" and "bad",
but in general the ones with lots of corners (like, F and X and W)
are "more useful" than those with long straight edges, (like L and I).
But every piece has both good and bad qualities, and times it should
be used, and times it should be saved.
Take for example, the I (or I5 as it called in online games):
Good qualities:

it takes you as far as possible in one direction,
it can cut off an opponent in some situations where no other piece will, because it's the only one that's 5-long.

Bad qualities:

only 4 corners, so vulnerable to being cut off easily itself
those long edges set up nice places for the opponents to play on  (called 'leaks') which cannot be blocked by the color of I5.

That, and just about every other piece, is a two-edged sword
(with the I5 being most sword-like in appearance!)
For a detailed look at "The 4 most valuable Pieces"
written by an expert player, see
http://blokusstrategy.com/?p=470
And for standard piece naming among online players, see
http://blokusstrategy.com/?p=48
The previous answer that said the the I4(straight piece 4-long) and O4(square)
are the hardest to play was absolutely right.  In online games, they are
the most frequently unplayed pieces, with the square failing to play over half the time.


Requiring Admin approval for profile changes

Question: So I'm looking for some suggestions. I have a client who needs to import user data from an old application they'd like to deprecate into an EE4 installation and integrate how they listed member data the same way on the old app. Most of this stuff is easy, but one of their requests is that if a Member can edit their own profile, that those edits be approved first by a SuperAdmin before going live.
I'm looking over these three add-ons:
User: https://eeharbor.com/user
Visitor (previously Zoo Visitor): https://eeharbor.com/visitor
Zeal Smart Members: https://devot-ee.com/add-ons/zeal-smart-members
And so far this functionality doesn't seem to be implemented anywhere.
The closest thought was using Visitor, which creates Channel Entries to store member data. Then I thought maybe something like Better Workflow was still out there, and I could use that so when a member profile entry is updated, it automatically goes in to the draft/review status, where a Super Admin could approve. But of course, that add-on is deprecated, and I can't seem to find any modern equivalent.
I know that EE isn't really built to be a full featured member management system, but I was hoping there was some middle ground. Has anyone successfully created anything like this? Or have any suggestions?
If an add-on like Better Workflow exists and works for EE4, I can probably build the whole thing out with Channel Entry tags and the Channel Form, as the member data being imported are members that already have accounts in the EE4 system, so I could cobble together a simple version of Visitor without it, but I still need to allow for profile edits to be reviewed.
Answer: This might be of help.
https://boldminded.com/add-ons/publisher-lite
Basically a manager of workflow logic.
Comment: I'll test it out, thanks.


When measuring a resistance using a multimeter it is a few percent out. Why?

Question: For example, if you were to put 5V across a \$150\Omega\$ resistor and measure its resistance with a multimeter, the reading would always be a few percent off the true value. What reasons might there be for this inaccuracy?
Comment: When measuring resistance you have to unplug the source. The MM uses current/voltage for resistance measurement
Comment: I am not sure, so sorry if this is a basic suggestion, but are you familiar with the fact that all resistors have a specified tolerance? Most designs can get away with a resistance of +-  certain percentage. You only go for tight tolerances when the need arises.
Comment: The multimeter and its leads also contribute errors to your reading.  The total error that you measure should be within the limits of (meter accuracy) + (resistor tolerance).
Comment: Please note that editing your question title to read "[SOLVED]" is not appropriate at StackExchange sites. Instead you should click on the check mark to the left of the answer that you consider best solves your problem.
Comment: Minor tip: '5 V' not '5 Vs' which would be read as volt-seconds.
Answer: The resistor may have a 1% or 2% tolerance (5% resistors used to exist, but are pretty rare these days, at least for professional suppliers).
Then check the specification of your meter. I would be surprised to find it had a better accuracy than 2% unless it was a really expensive one.
These tolerances can add up worst case, to give you 3% to 4% error, with meter and resistor fully inside specification.
Answer: When measuring resistance, it is generally good to disconnect it entirely from any circuit. In this way, the multimeter isn't measuring the resistance of the circuit, but is only measuring the resistance of your resistor.
Answer: The connection between probes has a finite resistance that needs to be zeroed out.  Touch your probes together to see if you get zero volts.  If you don't, some meters have a way to zero this out, or you can do it in your head.
At 150 ohms, 3 or 4 ohms in series in the probes/meter is a significant percentage.
Of course, you need to remove the resistor from the circuit for accurate measurement.  If you are measuring HIGH resistances, you also can't hold the ends of the resistor in your hand, as your body impedance in parallel can impact the measurement.
Answer: The multimeter itself is actually correct because all resistors have a tolerance (so the resistance of the resistor could be +/- a certain percentage).
The multimeter measures much more accurately and gives you the real value of the resistor.
You can get more accurate resistors if you need however for simple, 'normal' uses, a normal resistor with a 1%-5% tolerance should be fine.
Answer: Commercially available resistors will typically be 5% or 1% tolerance, which means that within their operating temperature range, they will deviate no more than that much from their nominal value.
When you put some voltage across a resistor, it will conduct current and start dissipating some heat. This will cause a change in temperature, which will in turn change the actual resistance, but should still keep it in tolerance range.
On a side note, Your multimeter's manual suggests to remove components from circuit board while measuring their attributes. If a component is within a powered circuit and you attempt to measure resistance/capacitance/hFe etc, it may give widely incorrect readings, and may also kill your multimeter.


What call sign does Marine One use when the President is not on board?

Question: How would the pilot of Marine One identify himself to air traffic control without the President on board? Does it have an N-number? If anyone knows, I would like a specific call sign/N-number of any of the Sea Kings. In particular, how would a Sea King pilot flying alone identify themselves to air traffic control?
Comment: They wouldn't use the helicopter type after the initial call for clearance. Just something like Nighthawk 1. Just like when an airliner calls, they don't give the type of aircraft. e.g. Southwest 2932 or United 133. Military aircraft do not have N numbers but they do have identification numbers and can use them instead of mission identifiers.
Comment: The Marine squadron that runs Marine 1 and the decoys is HMX-1. I believe that their callsign is 'Nighthawk'. There are several lists out there of military callsigns, but not having been in the military, I can't tell if they are accurate. Anyway, they say that NIGHTHAWK Helo in Marine One party, or Pres not aboard
NIGHTHAWK CH-46E HMX-1, MCAF Quantico, VA (CH-53D) http://www.ominous-valve.com/callsign.txt
Comment: So if one of the Sea Kings is flying around without the president on board, they would just say something like "JFK, this is VH-3D Nighthawk"? No specific N-number, as with most aircraft?
Comment: @birdus military aircrafts have tail number but that has nothing to do with their callsign. Callsign is most time depends on operational needs. Not registration. They work in different world from us civils.
Comment: @vasin1987 So is my guess correct, then, that the pilot would say something like "JFK, VH-3D Nighthawk" to establish contact with the tower rather than "JFK, VH-3D November-12345"? I'm just trying to piece this together from the various tidbits that people are giving me here.
Comment: @birdus my guess too that this is correct.
Comment: I'm curious if this question refers to the radio call sign or the transponder code.
Comment: The question is based on a false premise that some aircraft has the permanent call sign "Marine One", and may change it when not carrying the President. But actually this is the other way around: Every military aircraft uses usual military call signs, and any military aircraft can carry the President. In that case it uses a temporary "xxx One" call sign, "xxx" depending on which branch it belongs to.
Answer: Marine one is the call sign of any of the (300+) United States Marine Corps aircraft carrying the President of the United States. So, if he's not on board, the aircraft reverts back to its original radio call sign.
In case you are asking about the Marine Helicopter Squadron One, you can find the ID from helis.com. HMX-1 uses the call sign 'NIGHTHAWK' usually, but this is prone to change depending on the circumstances. From the site:

In Korea, call signs changed on a regular basis; during the Vietnam War, squadrons might use the same call sign for more than a year. Today, squadrons deploying to a combat zone,i.e. Iraq and Afghanistan, are assigned a "theater" call sign for use during that deployment only.
Comment: @birdus They'd get a callsign assigned for the mission by their planning and operations department. Often that will be "Nighthawk" followed by their tail number, so e.g. "Nighthawk 205" for aircraft #205, but doesn't have to be. When flying in formation, you'd get "Nighthawk 205, flight of 3" if 205 leads a flight of 3 aircraft.
Comment: @birdus 205 is just an example of a possible tail number, not one I know to be used by that unit. Mentioning your type is more something for VFR aircraft that don't have a filed flightplan (the filed plan would mention your type and you'd only then mention it if the actual aircraft used were different). If you did it at all, it'd be something like "Kennedy approach, Nighthawk 205, flight of 3 VH-3s, with you 5000ft 5 miles from Ellis Island".
Comment: Maybe I'm just dense, but it's not at all clear to me what the tail numbers (radio call signs) of the Sea Kings are from that web page. And yes, I'm talking about the Sea Kings of HMX-1.
Comment: Okay. I see. So when talking to ATC, they might initiate a conversation by saying something like: "JFK,  VH-3D Nighthawk"?
Comment: @jwenting Is "205" an actual tail number of any of the Sea Kings? I'm looking for actual numbers here, if those are known. Would they start their identification the same way another aircraft would, such as with "VH-3D"? So would their initiation of a conversation with a tower go something like "JFK, VH-3D Nighthawk 205"?
Answer: You seem to be confused about a couple of things. To clear everything up and reiterate some of what was said in other answers:

US military aircraft do not have "N-numbers" but they do have registration numbers (Bureau Numbers or BuNos).
Just like civil airliners, which have N-numbers but usually use callsigns and flight numbers instead, military aircraft will often identify themselves using a callsign and mission number.

When identifying using the BuNo, ATC will refer to the flights using "the service name, followed by the word 'copter,' when appropriate, and the last 5 digits of the serial number" (FAA JO 7110.65 2–4–20 6a). For example, the Sea King with the registration number 159357 would be "Marine Copter Five Niner Three Five Seven" (VM593571).
If not using their registration number as an identifier, Navy or Marine fleet and training command aircraft use "the service name and 2 letters, or a digit and a letter, followed by 2 or 3 digits" (2–4–20 6h2), for example "Marine Four Charlie Two Three Six" (VM4C236).
USAF, ANG, and "Military District of Washington priority aircraft" use "pronounceable words of 3 to 6 letters followed by a 1 to 5 digit number" (2–4–20 6h1), which is the "tactical callsign" others have alluded to. Apparently HMX-1 uses "Nighthawk," for example "Nighthawk Eight-Four" (NTHWK84 or similar; the spellings can be forced at times).
So a Marine pilot from HMX-1 who is calling ATC might identify themselves as follows:

Potomac Approach, Nighthawk Eight-Four, flight of three Sea Kings (type code S61).

The actual mission number used in the identification will be assigned by the unit's planning and ops department, as jwenting said, and may or may not have any relation to any number painted on the aircraft.

1The service prefixes for registration-number IDs are as follows: Air Force: A, Army: R, Coast Guard: C, National Guard: G, Navy: VV, Marines: VM (7110.65 2–3–5 b4a).
Answer: US military aircraft use mission callsigns, which can change with every flight, not tail numbers. Therefore, it is impossible to provide a comprehensive list for what a particular aircraft might use.
That said, squadrons often perform the same mission repeatedly, which means using the same callsign prefix, e.g. "Nighthawk" for the squadron you're asking about. That prefix is usually followed by a mission number, similar to an airline flight number.
However, some missions are unique and therefore do not need a number, and some missions (e.g. Air Force One and Marine One) always use the same number. The only hard rule is that there should never be two aircraft in the air at the same time with the same callsign.
Comment: Guard helicopters very commonly call with their BuNo instead of a mission callsign, at least around me.


How can I make my search give results based on strings from a multi-line column on a list?

Question: I have created a list, and added a multi-line column to the list called "Description".  When I search I would like the search to provide results from what is in the "Description" column.  Currently my search results do not return anything related to what is in the "Description" column.  I tired to see if I could index the column, but that is not available to do.  Any help would be appreciated.
Answer: Unfortunately, the Multiple Lines of Text column cannot be Indexed!

Workaround
Try to create a column with a single line of text and mention the main keywords that already exists in the Multiple Lines of Text column

Unsupported Column Types for indexing

Multiple lines of text
Choice (multi-valued)
Calculated
Hyperlink or Picture
Custom Columns
Person or Group (multi-valued) (Lookup)
External data

Supported Column Types for indexing

Single line of text
Choice (single value)
Number
Currency
Date and Time
Person or Group (single value) (Lookup)
Managed Metadata (Lookup)
Yes/No
Lookup (Lookup)
Comment: Thank you, this helps.  Is there a way to pull out keywords from a multi-line column to add to a single line column without manually going through and doing that for every entry on a list?
Comment: You can create a workflow/custom solution to loop for each item and update the newly created column, but in your case, the issue is How you let the custom solution to know which words should be the keywords!!


Can I use another GPIO pin on the Pi 3 as a RX UART?

Question: I accidently plugged 5v in to the RX UART pin 15 on my Pi, now I'm unable to receive communication on this pin from my connected device. I was wondering if it's possible to use a different GPIO pin as an RX pin to receive serial ?
Answer: This question may sound simple.  However it is likely dependent on if the processor's hardware UART resource is mappable to different (functional) pins as well as if the Linux UART driver is flexible enough to be configurable for this alteration to the UART feature of the Raspberry Pi.  Even if both of these features are available, such a change likely involves recompiling the driver if not the kernel.  This usually involves having an installed compiler and installed kernel source code (you need the kernel source code even if you are only compiling the driver).  Not a light subject.
On the other hand, people do write code to simulate a UART on other Raspberry Pi pins.  This is usually done when the actual hardware UART is committed to another activity.  In such a case, this Raspberry Pi stackexchange answer provides a good example.
If you have further Raspberry Pi questions, you may have better luck if you ask them on the Raspberry Pi stackexchange web site.


How can ISRO's RISAT satellites search for the lost IAF AN-32?

Question: The Indian Air Force has lost contact with AN-32 (transport aircraft)  on a mission. ISRO is going to deploy RISAT to search for the missing plane as the search area has widened. How will such satellites  help? Are the new navy P8I Posiedon sub-hunter planes not fit to do such a task?
Comment: Questions get better attention if the title makes clear what the asker wants to know, and it makes it easier for others to find the information later, so i edited it to fit that standard style. Also i added a link to the Wikipedia article on the news story, as with time news links can break, while Wikipedia articles improve.
Answer: RISAT-1 and RISAT-2 both carry synthetic aperture radar systems which can create detailed maps of the surface below.  There has been talk of using these systems to identify wreckage on the ground for quite a while now, but in the late 1990s, when a lot of these ideas were being proposed, the resolution was simply too low to make it a reliable option.  NASA actually did some research in this area too, but that's been indefinitely on hold for quite some time.
Here's a sample paper from the late 90s
http://wmsmir.cits.rncan.gc.ca/index.html/pub/geott/ess_pubs/219/219846/13148.pdf
Abstract: (emphasis mine)

This  paper  summarizes  some  results  of  studies  at  the  Canada  Centre  for  Remote  Sensing  (CCRS)  using  Synthetic  Aperture  Radar  (SAR)  imagery  from  spaceborne  systems  for  the  detection  of  crashed  aircraft.      Studies  have  been  carried  out  using  detected  products  (intensity  values  only)  and  interferometric  methods   (using   complex   imagery).      Due   to   the   low   resolution   of   single   polarization single frequency spaceborne SAR imagery  (approximately 8 metres ground range being the best currently available from operational remote sensing satellites),  it  is  seen  that  such  imagery  cannot  currently  be  used  with  much  optimism  although  the  techniques  themselves  show  promise.  Further  study  is  needed  to  examine  if  the  better  resolutions  that  will  be  available  from  future  systems  such  as  RADARSAT-2  make  possible  the  reliable  detection  of  crashed aircraft.   Other research, not described in this manuscript, is
  underway at CCRS through  the  support  of  the  National  Search  and  Rescue  Secretariat  examining the  contributions  to  Search  and  Rescue  that  can  be  made  using spaceborne polarimetric SAR systems including RADARSAT-2.

According to this article, RISAT-1 has a resolution that can be varied between 50m and 3m, and also has a "spotlight mode" where this resolution can be as good as 1m.  This is definitely in the range where it could be useful if we have a general idea of where to look.
Realistically, I'm not sure how much good the satellites will do, especially compared with the aircraft and submarines already deployed, but it is an idea that works in theory, so you can't really fault them for going for it.