How to handle client when developer worked very well and tester are not finding bugs in Application

Question: I am working on a project, on that project developers are doing a very good job that we hardly find the bugs on that application. Everything is running very smoothly client is very happy with the developers. but now client think that we are not reporting bugs & we are not doing anything which is not true Now how to handle this situation. How to explain this thing to the client.
Comment: Possible duplicate of [What should Testers do if they are not able to find good defects in the product?](https://sqa.stackexchange.com/questions/22139/what-should-testers-do-if-they-are-not-able-to-find-good-defects-in-the-product)
Comment: I went through that Question but I couldn't find how to deal with the client in this situation.
Comment: @BharatMane this is completely different from your refer Question.
Comment: Possible duplicate of [How can I switch from manual testing to writing automation?](https://sqa.stackexchange.com/questions/3755/how-can-i-switch-from-manual-testing-to-writing-automation)
Comment: @NarendraC It's different from your refer one
Answer: While testing this application I'm sure you might have documented your test plan and also the cases you executed for testing.
If so, you can share those documents with the client saying these are the cases we have executed and also share with the client your test coverage data to show which areas and scenarios you have covered. From that the client will get an idea what testing was done for the application.
You can also go through the test cases yourself to see if you have missed anything or see if you can come up with more cases to test the application with. Also share this report once you're done testing.
That way client will know that the application was tested properly and not many issues were found during testing. So they won't complain why a huge list of bugs has not been reported to them.
Comment: I agree with you, we did all the thing you mention but client believe that they are not getting ROI from Test Dept as everything is going very smooth. At the end client saying that he is getting a very good product without testing dept then why he spends money on testing.
Comment: So, in your team testers aren't involved in requirement analysis and business scenario testing? Plus, if the product isn't tested at all and there is a bug to occur, will the client then come yelling at your dev team for not doing good work? Or will he accept the fact that he didn't invest in testing and hence this occurred (PS - testing also doesn't guarantee 100% bug free product)?
Comment: Now he strongly believes that without testing he can have a very good product and I don't know how to break his belief.
Comment: @nitinr, it may come down to use evidence; learn a lesson the hard way. Once he witnesses you can not alway have a good product without testing, then he will believe you.
Comment: @ Yu Zhang You are right brother, I know that at the end he will come to us when a product becomes more complex and required regression, But want to give one more try to explain him the importance of testing so that I don't lose the business.
Answer: I'd like to add another view of QA engineer.
Do you have story during development phase to tell your client? Do you add value to the product? I bet you do as Quality Assurance. Go tell them.
Since we should be a QA rather than a tester. We do assurance the quality of software and quality is not a thing that only measure after developer finish the last line of code. Actually, Quality need to be addressed before developer start the first line of code.
With team, QA grooms the client's requirements with a view of system impact, usability, UX, and etc. QA produces test approach for positive and negative scenario. We plan for performance and failure test. ... blah blah blah it's a lot of thing QA do to assurance the quality.
Even if none of a single test is fail when we did a test. But I think the things, QA did affect developer and the software somehow. Maybe developer had go over our test cases and realized he missed a detail. Then the discuss was arranged and developer did a fix before he shipped the software to test.
This is just an example. I believe you did and you do these things already. If this kind of client issue happen again. Go tell them, what is the value that you add to software, not only the test cases that you test against it.
Good luck.


What causes ground losses in a HF antenna system?

Question: This applies to mobile and fixed installations. What are ground losses, and how can they be minimized? It seems to involve proximity to the ground, but what is the mechanism that causes loss? Does antenna installation height influence ground loss in any way?
Answer: While ground effects are common concerns in almost every antenna and radio system, they are particularly important in the case of a monopole antenna. Monopole antennas, including quarter wave verticals along with many other electrically short verticals, are different from dipoles because the currents going into the elements do not balance. While a dipole has equal but opposite currents at all times, a monopole can't. One half of the signal goes into the antenna, and the other half has to come back through the shield of the coax, which is connected to ground.
When we're talking about antenna modeling, we describe the ground plane as an image plane - everything above it is mirrored below it. So in theory, the monopole should act as though there was another monopole directly below it, being fed 180 degrees out of phase. We do see the correct amount of current returning through the ground path for this model to work - we do have equal but opposite currents - but while your antenna is low-resistance wire and most of that current is being radiated, the ground typically has somewhat higher resistance. It's impossible to set a value here, because it is dependent on soil type, weather, how deep the water table is, and other factors, but it is greater than that of your antenna.
Because of this resistance in the ground, some of the power coming from your radio will be lost to normal resistive heating. Since, at a constant power and given $P=VI=I^2R$ the increased resistance in the ground results in decreased current into the ground (at constant power). Since the antenna and ground currents must be equal but opposite, that also decreases the current flowing into your antenna and therefore your actual radiated power.
You also can't just stick a multimeter into the ground to find this resistance - it's the resistance from your antenna feed point to the point where the coax shield is grounded, but it is frequency dependent because there is a capacitive component as well. An antenna analyzer can be used to detect the total resistance (including radiation resistance of the antenna) and this can be compared to a model with an ideal ground (perhaps obtained from EZNEC or another modelling program) to get the "extra" real-world losses, including ground loss. This also explains why height factors in: Your antenna system is effectively a series resistance (from ground loss and other factors), capacitance (between antenna and ground and other effects), and inductance (from loading coils and other effects). If the antenna is mounted further from ground, the capacitance decreases, and so the ground loss becomes a greater part of this total reactance, which is why it is better to have your antenna near to a ground and to have a ground that is as low resistance as possible. An extra way to help this is to install radials - wires underground at about a quarter wavelength which would act as a lower-resistance path for the return current to take.
Comment: @Bill-K5WL If Phil's answer is what you are looking for, than you urgently should rephrase your question to: "How does the vicinity of ground influence the directivity of an HF antenna?" Dan's answer is the only correct answer so far in dealing with ohmic ground losses. [This answer](http://ham.stackexchange.com/a/494/250) might also help in understanding this difference.
Comment: Thanks, I wish I could accept both answers, because yours is half the answer and Phil's is the other half. However what I was looking for (though it wasn't necessarily clear) was Phil's answer.
Answer: To add to what Dan is saying, for (horizontal) dipole antennas, ground height is important because although a dipole doesn't require ground to work, ground is still a (lossy) conductive plane, and you still get an image. That is, it appears that there's another dipole, fed in anti-phase, underground. Even if nothing in your transmitter or antenna is connected to the ground, your antenna will be capacitively coupled to the ground. There is no avoiding it.
If the dipole is close to the ground, then the currents in the ground can be quite strong, incurring significant resistive losses along the way. You could put radials (or any conductive mesh, really) in the ground to mitigate this.
But also: this image makes your dipole a kind of phased array. Depending on the spacing of the antenna and it's image, this might make a phased array that helpfully directs most of the RF energy at the horizon (low takeoff angle, desirable for HF DX exploiting skywave propagation), or unhelpfully straight up (useless, unless you are trying to exploit NVIS propagation on communicate with something in space).
Radio Antenna Engineering has a more detailed explanation, and this:

One interesting thing to note about this image: you can't get maximum gain in any direction until the dipole is $0.25\lambda$ high. Remember, the image is twice this distance away, and anti-phase. Below this height, in any direction you will get at least partial phase-cancellation. At $h=0.25\lambda$, you have two antennas, in anti-phase, $0.5\lambda$ apart, which makes the add instead of cancel, but only if you are directly over the antenna, which isn't useful for skywave propagation. Thus, the general recommendation to get a dipole something like $0.5\lambda$ high, which sends most of the energy at a reasonably low take-off angle, making the best of the transmit power available.
Comment: This is an explanation of how antenna directivity gets influenced by the vicinity of ground, not about how power is lost in the ground.
Comment: @on4aa yes, except for the parts where I discuss high currents when dipoles are near the ground associated with resistive losses, and how the antenna image causes phase cancellations in all directions at low heights, and how other heights can cause useful energy to be lost to space, you are right. I'll add that this is complementary to Dan's answer. Oh wait. That's already the first sentence.


Is there a way I can deter geese from visiting my yard and pond?

Question: Has anyone had success with any form of goose deterrent? I currently have a small flock of about 10 geese that like to leave their scat all over my driveway and lawn.
I have about 2 acres of lawn and a half acre pond on the property.
Comment: Are they sleeping on your property too? Or do they come and visit for some time and then leave?
Comment: They come and go. Sometimes they sleep there. There are around 5 or 6 ponds in the area so I think they bed down randomly.
Comment: The lawn is goose food. Consider how much you actually use the lawn as lawn and consider converting as much of it as you don't use actively into other vegetation.
Comment: @stormy goose shit is also dog food, which my dog then throws up and tries to re-eat. The geese need to go!
Comment: Goose shit is lawn food...they just eat it down way too short.  Geese are just a wonderful addition to a property.
Answer: Luckily it sounds like you just have to make your yard/pond less attractive than the other yards/ponds nearby. It's a fairly common problem for people with water features such as ponds on their property, and as such there are several different ways that people have discovered to discourage geese from visiting. Your mileage may vary with these methods, and some of them might not even be an option for you. So use your discretion to choose which method you think will work for you.
Discourage access to water
Geese are lazy, and prefer to walk into the water from the shore rather than fly in and out like ducks do. So if you're mowing to the edge of your pond, you might want to consider doing some landscaping to make it less convenient for them to visit your pond, than the other ponds.
How you landscape the area by the water is up to you, but the goal is that the geese won't easily be able to walk into the water from the land. It could be something like not mowing the area at all and letting the area by the water grow unchecked, or you could even plant some decorative plants or grasses by the water if the unkempt grass sounds like it would be an eyesore, even large decorative rocks that would be difficult for geese to walk across could do the trick.
Other options that might not be as attractive, I think, are: Making the slope to the water steeper, as that would also make it more difficult for geese to access. Or, you could run a wire around the pond, about 6 inches off the ground, right by the water's edge. That acts as a fence of sorts that makes it inconvenient for the geese to get in and out of the water.
If the other ponds are easier to access than your pond, the geese will most likely visit those ponds instead.
Don't feed them
Definitely stop feeding them directly if you are doing so. Offering handouts is a good way to get geese to return for more. But there are also ways you might be offering geese easy meals on your property.
Geese like to eat the short, manicured grass, along with the new shoots that come with it. An easy way to make your lawn less palatable to geese is to keep your lawn at a higher length than normal. I would say you should try to avoid mowing it shorter than 3-4 inches minimum. That should help keep the grass mature and tougher than the geese will prefer.
You might also want to consider cutting out using fertilizer for a while, to make your grass less nutritious than they need as well.
There are some grasses that attract geese as well. Kentucky Bluegrass is a well loved favorite of geese. I've heard that they don't like Fescue, but I don't know if that's true or not.
I don't know much about it as I haven't had any desire to use it, but I've heard that Methyl anthranilate is effective. All it is is a bitter flavoring that you would sprinkle in your yard and it would make it taste bad. There was a study done on it's effectiveness though.
Scare the geese away
First, be sure not to do the scaring yourself, as geese are ornery creatures.

Decoys:
Sometimes a good old scarecrow and/or strips of mylar tape can be enough to do the trick. Part of the problem with geese being such large birds, is that they aren't scared of the usual decoys you might normally use for pests, such as owls, and might not be so scared of humans either (especially ones that don't really move).
One decoy that might work depending on where you live, is a floating gator decoy. It's simply a decoy that you can float in your pond, and it's meant to keep away larger birds such as geese or herons that might be a hindrance to ponds with fish in them.
Another option might be swan decoys. This is give or take I think. Swans are more aggressive and territorial than geese, so having swans in your pond could deter geese from visiting just so they can avoid the possible confrontation. The problem is that the geese could take it to mean that your pond has a good source of food since there are swans there, and be attracted to it. I've seen it go both ways.
Otherwise I would suggest a coyote decoy, as coyotes would be the most common natural predator of geese, and should make any of them uneasy being in your yard.
Chasing:
Other people have devised more hands-on methods of scaring the geese away like the goosinator. Which really any model airplane or remote control car should be effective enough to chase the geese away.
If you have a medium to large sized dogs, it might be worth letting it loose to chase the geese for you. Herding dogs work best, as geese get put off by the herding methods. Sometimes you can hire goose-herding services depending on where you live.

Don't let them sleep
The geese will want to sleep in or around the pond at night. The best thing you can do here is to make your pond the one that they can't sleep in, and they'll be more likely to move on to a neighboring pond to spend their time.
There are a couple different ways to do this, the most common is placing a flashing light in an around the water. The ones you can find on AwayWithGeese.Com are pretty pricey, but they give you an idea of what you would want. A couple lights in the yard, and some on buoys in the ponds.
In combination with lights, or just an alternative to, would be something that makes noise at certain intervals throughout the night. Just something that doesn't allow the geese to get a good night's sleep while they're staying on your property.
Comment: I added a low, green wire fence around the less crowded sections of the pond. Now they just go up to fence and honk at it angrily until I come out and scare them away with a broom. Results!
Answer: Canada geese are a big problem all over Eastern North America. Some of the solutions that have worked but may not work for you are:

do not mow areas adjacent to water.  They are not too mobile through thick tall grass and like to access the water easily.
plant trees and shrubs or fence next to the water to limit access
plant emergent aquatics next to the shore to limit access
a few government departments where I live have hired a service that uses trained Border Collies to scare the geese away.  As they are herders they can be trained to sneak up and scare the geese without harming them.  You mileage may vary depending on the dog and the effort you put into training them.

By the way for our members from the United States

Federal law protects Canada geese. It is illegal to harm geese, their
  eggs, or their nests in the United States without permission from  the
  U.S. Fish and Wild Service (USFWS). Geese may be harassed or  scared
  away without a permit as long as the geese, goslings, eggs,  and nests
  are not harmed. USFWS allows resident Canada goose  eggs to be treated
  to prevent hatching....
Answer: One of the best methods for scaring away geese is a lazer light. Get a powerful one on ebay and watch them fly away. The downside is after a while they get used to it and you will have to get something else to keep them at bay. I have a four wheeler and chase them off with that, but that only works when I'm home. I also placed some driveway markers around the area that they like to nest in and ran string between the markers about a foot off the ground, this seems to work. The main thing is you have to keep switching up methods to keep them away. But the lazar light does work the best.
Comment: I was wondering. Under a watt I hope.


Switching siddur style (Nusach)

Question: I'm Ashkenazi and I usually pray with a Nusach Sfarad or a Rinat Israel siddur, but I have a pocket siddur that I use for travel that is Sefaradi. Can I say birkot hashachar in the Sefaradi version, and then say the rest with an Ashkenazi siddur in the synagogue? What about praying Shacharit with a Ashkenazi siddur and Mincha with a Sefaradi siddur?
Answer: In general one should not change once nusach, especially if you follow a strong family tradition (mesorah). Various poskim discuss the possibility to change once (incl. the need for Hatarat nedarim [annulation of vows] in some cases) but nowhere do you find people praying according to different nusachim during the day.
If you pray in a synagogue using a different nusach from yours, you should say private prayers according to your nusach and the public parts (e.g., kedushah) according to the synagogue's nusach).
See various sources and detailed study here according to R Eliezer Melamed in Pninei Halacha, here from him as well in short, here and here.
So it looks like you need a new travel siddur and of course CYLOR for your specific case.
Comment: Note the wrong nusach is prob better than nothing if you need a text to read
Comment: @mbloch In academic writings on tefillah, it's common to see נוסחים as the plural, whereas נוסחא/נוסחאות is used to mean "reading(s)" (ie. variants within one נוסח).
Comment: Plural is "nuschaot."  *If you pray in a synagogue using a different nusach from yours, you should say private prayers according to your nusach and the public parts (e.g., kedushah) according to the synagogue's nusach).* Rav Moshe Feinstein gives the option of doing that, or entirely following the synagogue.
Comment: @Shalom just seeing this now. On nusachim vs. nuschaot we had a discussion on this in meta. I checked and in Israel we use nusachim. Nuschaot means formulas so I don't quite understand how it can become the plural of nusach but am sure there must be a reason. On the nusach there is an issue of "not forsaking your mother's Torah" but the issue is quite granular, e.g., if one moves to a different country or changes synagogue vs. simply being once in a different synagogue. Interesting question on its own!
Comment: Further note: according to many respectable poskim (including R' Moshe Feinstein זצ"ל) one who davens Nusach Sephard (Israeli "Ashkenaz") may switch to Ashkenaz without Hatarat Nedarim. This is because it is an extension of the Chassidische minhagim which the Steipler and R' Moshe say may be put aside due to their novelty.

Switching siddur style (Nusach)


How to prove that $\lVert \Delta u \rVert_{L^2} + \lVert u \rVert_{L^2}$ and $\lVert u \rVert_{H^2}$ are equivalent norms?

Question: How to prove that $\lVert \Delta u \rVert_{L^2} + \lVert u \rVert_{L^2}$ and $\lVert u \rVert_{H^2}$ are equivalent norms on a bounded domain? I hear there is a way to do it by RRT but any other way is fine. Thanks.
Comment: Wasn't my down-vote btw...
Comment: What is RRT short for?
Comment: @SamL. It's Riesz Representation Theorem
Comment: Why the downvote? I didn't put any working done because I have no idea how to start, and I have searched to find a proof but no luck.
Comment: Note that if $u \in H^{1}_0$ further then we can bound the $\|u\|_{L^2}$ by $\|\Delta u\|_{L^2}$ using Poincare inequality .
Answer: If you want an $H^2$ estimate up to the boundary for arbitrary bounded domains, I'm not sure it's even true. You can bound $\|u\|_{H^2}$ on compact subdomains (this is interior $H^2$ regularity for elliptic equations), or globally in domains with smooth boundary (this is boundary $H^2$ regularity). Both topics are covered in details in PDE by Evans (sections 6.3.1 and 6.3.2 of the 1st edition). It would be impractical to reproduce the proofs here, as they cover 4 and 5 pages, respectively. Besides, Evans' is a fine book to read for any pde_lover.
These lecture notes follow Evans pretty closely.
Answer: As user53153 wrote this is true for bounded smooth domains and can be directly obtained by the boundary regularity theory exposed in Evans.
BUT: consider the domain $\Omega=\{ (r \cos\phi,r \sin\phi); 0<r<1, 0<\phi<\omega\}$ for some $\pi<\omega<2\pi$. Then the function $u(r,\phi)=r^{\pi/\omega}\sin(\phi\pi/\omega)$ (in polar coordinates) satisfies $\Delta u=0$ in $\Omega$ and it is clearly bounded. On the other hand the second derivatives blow up as $r\rightarrow 0$, more specifically $u\not\in H^2$!


Apache2 on Ubuntu 11.04 - New Virtual Host 403 Forbidden Error

Question: I receive the following error when trying to access a new virtual host:

Forbidden
You don't have permission to access / on this server. Apache/2.2.17
  (Ubuntu) Server at www.local.ttr Port 80

The apache log file for this virtual host contains the following error:

[Tue Aug 09 13:54:42 2011] [error] [client 127.0.0.1] Symbolic link
  not allowed or link target not accessible: /var/www/ttr

I have set up a .conf file in sites-available and created a symlink to this in sites-enabled. This file has the following content:
<code><VirtualHost *:80>
    DocumentRoot "/var/www/ttr/Public/public"
    ServerName www.local.ttr
    ErrorLog "/var/log/apache2/ttr-public-error.log"
    CustomLog "/var/log/apache2/ttr-public-access.log" common
php_flag log_errors on
    php_flag display_errors on
    php_value error_reporting 30719
    php_value error_log /var/www/ttr/Public/application/logs/logs.txt
</VirtualHost>
<Directory "/var/www/ttr/Public/public">
        Options Indexes FollowSymLinks
        AllowOverride all
        Order Deny,Allow
  Allow from all
</Directory>
</code>
The path /var/www/ttr is a symlink to a folder within my home directory /home/gordon/ttr which contains all projects including a project called Public.
Could anyone give me any pointers on how to fix this problem? It is driving me berserk!
Answer: Apache should have execute permission for /home/gordon/ttr [and everythng in there]


Osmos hard level strategies

Question: I have a lot of problems with beating the Epicycles levels in Osmos -- do you have any tips for transitioning orbits without wasting a ton of material?
Answer: I think there are a couple key ideas that help for transitioning orbits. First, the path visualization is very useful to have on. On the orbiting levels, I tend to eject material only forward and reverse of my direction (except for emergency/panic maneuvers). I think that's the most efficient way to increase/reduce the size of one's orbit. Also, it's usually easier to increase the size of the orbit than reduce it.
The best way I've found is to break out of your current orbit in an arc that intersects where the next attractor will be.

When you get close, decelerate enough to prevent hitting the wall.

Stabilize your orbit.
Answer: Check this page out. It includes tips and a video playthrough of the hardest Epicycles level. http://www.hemispheregames.com/2010/02/03/osmos-rage-part-4-roadside-assistance/
Cheers,
Eddy

Osmos hard level strategies


Illustrator brush and pentool line. Visually same thickness, why there is a difference in points?

Question: I created an illustration using pentool and brush in Illustrator. While I was trying to asses if the thickness of lines would be good enough for the printer I realized that my lines made with brush and pen tool, even if look they same, they have a different thickness in points. See the screenshot.

The line made by pentool has more than 1 pt so it is sufficient to print. The line made with brush looks even a bit thicker, even though Illustrator sais it has only 0.56 pt. Should I just assume that brush lines are ok for printing, becuase they are visually as thick as 1,3pt pen tool lines?
Can someone explain why there is this difference occuring?
Maybe brush settings has something to do with it? I attach the screen below.

Thanks
Answer: When you use a brush, the stroke thickness is effectively a percentage relative to the brush's default size - so .56 means you get 56% of a 3-point brush - so around 1.68 pt.
Hope that helps.


Is it possible to unlock my Samsung Galaxy 3(GT-i5801)?

Question: I moved to another country and absent-mindedly bought a SIM card for my GT-i5801 (from Orange UK) Now it's asking for a network lock code. I have searched the net and everything points to me going to a "phone" shop to unlock this, however I'm not conversant enough in the local language to understand people yet and want to carry on using my phone.
Is there anyway to unlock this phone? Either that or I have to wait a month until I can get back to the UK.
Answer: You should call your carrier in the UK and explain that you need to unlock your phone because you are travelling.  Unless they're being particularly unhelpful a carrier will normally give you the unlock code for that purpose.
Edit: It looks like the unlock code may be stored on the device and accessible as with many Galaxy phones, most easily if you are rooted.  Check out this AndroidForums guide.
Answer: Yeah nowadays it's very easy to get a phone unlocked and get rid of excessive roaming charges and get the freedom to change network provider. Recently I unlocked my cellphone, not Samsung but Blackberry, in something like 3-4 hours. Lots of vendors can do it like codes2unlock and myphoneunlock, you could try it.
Answer: Yes, it's possible to unlock your Samsung Galaxy 3 (GT-i5801) through online mobile unlock services. I would recommend you to use theunlockarena.com to get the unlock code. You need to specify the IMEI number. Then, they will give you the unlock code through E-mail.
Comment: Thanks but I can't even remember what this phone looks like anymore. :)


Coins with memory-intensive mining

Question: Are there coins that demand system memory rather than computing power? Which coin brings me the most mining profit if I have a lot of system DDR3 RAM (say 64 GB or more) in my personal computer?
Answer: There are memory intensive mining algorithms, but usually the "memory" being discussed is not of the DDR3 variety. That 64 GB of DDR3 RAM you have is an excellent resource for many computing tasks (and enough to make me jealous), but is also dramatically slower than the L1 and L2 cache physically on the chip with your CPU. This is the memory we're talking about.
Memory intensive mining algorithms came about in reaction to GPU (and later FPGA and ASIC) acceleration. Because GPUs have so many cores, each core has access to only a miniscule amount of RAM, often an amount measured in kilobytes. Because Bitcoin's SHA256 mining algorithm has a tiny memory footprint, it runs quite nicely on such hardware. Some say this is a problem, others disagree.
CPUs, on the other hand, have relatively few cores sharing access to, on average, 64 to 128 kB of L1 cache and 2 to 4 MB of L2 cache. By virtue of being on the same die as the CPU cores, this RAM is extraordinarily fast and has amazingly low latency. This, it turns out, is an exploitable difference that memory intensive algorithms take advantage of.
An ideal implementation of one of these "memory intensive" algorithms (for mining) will be tuned such that the RAM footprint required is higher than the few kilobytes available to GPU cores, but lower than the few megabytes typically available in L1/L2. In this way, the mining algorithm can be run at high efficiency on standard CPUs, thus maximizing the hashrate available to secure the network, but is still resistant to GPU/FPGA/ASIC acceleration. The CryptoNote algorithm used by Monero is a good example.
Sadly, few altcoins take such care with their implementation. Most either use so little memory that they are freely accelerated with GPUs or use so much that all mining processes eat into your good old DDR3 and lose efficiency. In short, there is almost certainly a coin out there that can make use of such an obscene amount of system memory, but that's almost certainly a sign that they did it wrong since the goal of such an algorithm should be to maximize hashrate on the target device (CPUs) for the sake of network security while preventing acceleration from non-target devices (GPUs, FPGAs, ASICs).
In any event, all proof-of-work systems currently in use are mathematical in nature. This makes the memory requirements somewhat secondary in nature - you will still require a lot of computing power to mine and it is this computing power that will largely determine your results. In a few cases the extra RAM may help, but your CPU will still be doing the heavy lifting.
Special note: In certain non-mining implementations of such memory intensive algorithms (like the scrypt implementation used in BIP38 encrypted keys) the poor efficiency caused by exceeding available on-chip cache can actually be a positive effect and is often used intentionally. By forcing the process to use slower memory we can throttle the number of decryption attempts an attacker is able to make in a given timeframe, which dramatically reduces the effectiveness of brute force attacks. This is why decrypting your BIP38 key on a phone often takes 30+ seconds - it's a feature, not a bug.
Comment: In what sense is using main memory a "loss of efficiency" ? The goal of a memory-bound proof-of-work is not "to maximize hashrate". Hash-rate is just some arbitrary measure that's not comparable across different proofs-of-work. It is nonsensical to see that SHA256 ASICs have vastly higher hashrates than scrypt ASICs and conclude that SHA256 is way more secure. Scrypt simply has to do a lot more work per hash. The same goes for a memory-bound pow that needs to do a lot of work accessing main memory. If anything,aA PoW dominated by main memory latency is more power efficient.
Comment: @David Perry so this has nothing to do with the GPU RAM per say, 3GB GDDR would be as good as 11GB as some GPUs have, in that sense?
Answer: With such fast main memory, I'm sure your machine would be pretty good for mining MemoryCoin whose proof-of-work algorithm, Momentum, requires a lot of RAM. Copied verbatim from its tech page:

Each hash requires 1GB of Memory to perform and encrypts 50GB of data.
  By contrast, the verification only requires 128K and less than one
  10th of a second

Be warned, though, it also requires a fast CPU (from same page: "it has a large AES component – chips with AES-NI instruction sets will fare much better"). Plus, I don't know of many exchanges that deal with it, nor how much it's worth - so can't say for sure if mining such coin would be the most profitable for you or simply the most efficient.
I'm sure your machine would have a slight advantage at mining other CPU-only coins, have you tried Protoshares or Quarkcoin?
Answer: Cuckoo Cycle is quite memory intensive, with 67% of runtime spent on main memory access. See https://github.com/tromp/cuckoo for an implementation and whitepaper.
Comment: I don't think memory access time is what's meant by "memory-intensive mining". Usually that means the process *uses* a lot of memory space, not bus bandwidth.
Comment: Cuckoo Cycle uses both; lots of memory space and bandwidth.
Answer: Try to search memory-intensive in whitepapers.
Check these results: https://whitepapersindex.com/?q=%22memory-intense%22
I see 14 whitepapers found.
EDIT: URL is 404, try Google Cache.

Coins with memory-intensive mining


Primers on Dystonia

Question: Where can I get a good biochemical overview of dystonia? I will be working in a research lab that focuses on dystonia and I would like to not be clueless.
Answer: A good article on the pathophsiology is,
The pathophysiological basis of dystonias, Nature Reviews Neuroscience 9, 222-234 (March 2008)
For a review of the treatment,
Treatment of dystonia, lancet neurology, Volume 5, Issue 10, October 2006, Pages 864–872.
A comprehensive textbook on movement disorders in general is The oxford textbook of movement disorders
Comment: this is a bit fragmented and hard to read - can you spruce it up a bit?

Primers on Dystonia


Is it possible to use data in a Related Data Extension to personalize content that is sent to the parent Data Extension?

Question: I am trying to determine if I can use data that is set up in a related (non-sendable) Data Extension to personalize an email that I will send to a parent (sendable) data extension. I have two data extensions, one containing subscriber emails and demographic information, and the other containing sold product information. I want to be able to use the related (non-sendable) product data extension to populate data on a newsletter based on which products each subscriber has purchased, but the product data does not live in the subscriber data extension. It is only a related data extension. Is there a way that I can use this relational data to drive my content?
Comment: I have a primary key that i have related the two data extensions together using. I have also related them in Contact Builder AND in Data Relationships (Email Studio)
Comment: What are you using to relate these two data extensions together? Is there a shared key or field between the two?
Answer: One way to accomplish this would be to use the primary key relationship to pull in the necessary data via AMPscript. The Lookup() function would be one such example that could accomplish what you're trying to to.
<code>    %%[

    /* Initialize variables */
    var @subPkey, @fieldFromProductDE

    /* Set the @subPkey variable to the primary key field on your sending DE */
    set @subPkey = AttributeValue("pkeyField")

    /* Use the Lookup() function to pull the productField value where DE1 primary key matches the primary key on product (in this case "productPkey") */
    set @fieldFromProductDE = Lookup("ProductDE", "productField", "productPkey", @subPkey)

    if @fieldFromProductDE == "ProductA" then
    ]%%

    Content Block A

    %%[Else]%%

    Content Block B

    %%[endif]%%

%%=v(@fieldFromProductDE)=%%
</code>
This will first pull in the primary key from your sending DE, and relate it to the primary key field on your related product DE. It will return the value from the field you've entered as your second argument in the Lookup function.
Comment: You could certainly do this through conditional 'if' statements. I've edited my answer to show an example of displaying different content based on the returned value for the "productField."
Comment: I would not be able to use this data to drive dynamic content within the message, would I? Meaning, if AccountA has ProductA, show ContentBlockA and NOT ContentBlock


starter looses symbol when added to the unity launcher

Question: I have a starter which I would like to add to the launcher. When I move the starter from the dash to the launcher, it will be added but you cant see anything as the symbol of the starter is lost. The empty space that represents the launcher can be used to start the script. Any ideas how to keep the symbol?
Answer: The icon that appears in the launcher is controlled by the .desktop file, mime type application/x-desktop, for that application.
In a .desktop there is a line item starting with "Icon=". that is where the location of the icon goes. Those desktop files are what you drag into the launcher.
By starter I can only assume you are actually talking about a .desktop file. Unfortunately the treatment of these .desktop files in Nautilus makes them difficult to edit. The displayed name isn't the actual file name and no editor is offered as an option to open the file.
What you need to do is use a terminal window and cd to the folder with the .desktop file. The system keeps them in /usr/share/applications but I suggest you keep any you've changed in ~/.local/share/applications. Do an ls in the folder and you'll see the .desktop files listed with the file names you'll need to edit them, for example on the CLI gedit file.desktop.
When you add your edited .desktop file to the launcher open the folder containing it and drag the file to the launcher. The .desktop files Nautilus shows in your .local folder may or may not be displayed as the application icon but as a generic text file with a .desktop name.
This is the process that works for me.
Answer: Restart Unity by logging out and in again or just Alt+F2 unity --replace. Then the icon should be displayed.


Rebuilding RAID 5 in HP Proliant ML 370 G5 Server

Question: One of our customer having HP Proliant ML370 G5 server with Windows 2003 SBS.That having 2*72GB(Single Port10K Serial SCSI) and 3*146GB(Dual port10K SAS) harddisks.Now that is going to full.I want to extend the current RAID with two additional HDD(Either 146 SAS or 300GB SAS).Is this possible or not?How I can rebuild the current RAID 5 without lossing any Data.Can you please tell me the steps for that???
Comment: possible duplicate of [Extend Raid5 with a new HD (HP DL380 G3)](http://serverfault.com/questions/20815/extend-raid5-with-a-new-hd-hp-dl380-g3)
Answer: First, Backup.
Second, Verify Backup, then backup again.
I'm assuming that your current config is that the 2x72GB are a RAID1 array, and the 3x146GB disks are the RAID5 array, and that any new disks will be added to one of the empty drive bays.
I believe that this is answered here:
Extend Raid5 with a new HD (HP DL380 G3)
(the HP software and hardware is
I think it may be possible doing it online using the HP Array Configuration Utility from within Windows (You do have the HP PSP installed, right?), I believe that you can add disks to a RAID5 array and set it to add the disk to the array.
Ensure that the server is on backup power and that there's no possiblity of Updates or a reboot happening; That would really break your filesystem in the middle of a rebuild.


I'm looking for a skype phone that works with ubuntu 11.10 any suggestions?

Question: Just looking for something basic on which I can receive and make calls as if it were a normal house phone.
My international calls are killing me on my mobile.
Answer: For Skype, you only need an audio device with a speaker and microphone. The "Skype Phone" devices marketed for plugging into your computer are just a USB soundcard in a phone-shaped package, so if you already have a working sound card that has a microphone input, use that with Skype instead.
Skype run nicely on Ubuntu. I usually download the .deb package from the Skype website.
Answer: What do you mean by "works with Ubuntu 11.10"? As far as I know, Skype phones are OS agnostic and only require an ethernet connection.
Answer: Skype can be downloaded to many mobile phones, for example android phones.  If your mobile is Internet capable you should be able to install Skype on it. Then you can uses Skype to Skype on your mobile and also Skype-out to ordinary phones anywhere in the world at cheap rates by putting some credit on your Skype account.


cpufreq not available 11.10

Question: on 11.04 I had cpufreq working on my "AMD Turion(tm) 64 X2 Mobile Technology TL-50 stepping 02" processors, however now on oneiric cpufreq won't load.
The core temperature of my cpu is normally 40 c, but lately it's cooking away at 75-80+ c and the fan is always extremely loud even when cpu usage has at 0.4%.
and after this dmesg | grep -i cpu I got:
Brought up 2 CPUs
Switch to broadcast mode on CPU1
Switch to broadcast mode on CPU0
Switched to NOHz mode on CPU #1
Switched to NOHz mode on CPU #0
ACPI: acpi_idle registered with cpuidle
cpufreq-nforce2: No nForce2 chipset.
cpuidle: using governor ladder
cpuidle: using governor menu
powernow-k8: Found 1 AMD Turion(tm) 64 X2 Mobile Technology TL-50 (2 cpu cores) (version 2.20.00)

I see something about governors and ladder there, does this mean the OS is able to scale my cpu's or not? If so is there a way I can determine it's working?
I saw that for other users that the wrong module had been loaded and by disabling it they were able to get cpufreq loaded. How can I tell what scaling module is loaded?
stats:
Ubuntu Oneiric 32bit
Dell Inspiron 1501
Answer: BIOS settings > enable "Powernow".
I recently had an issue with a faulty USB port so I disabled all the "extra" features on my BIOS so I could really nail down what was failing. When done I forgot to re-enable power management.

cpufreq not available 11.10


Trigger linux command using external web service

Question: I am looking at different options of triggering linux command on NATed box that has internet access.
I know that I could use combination of IMAP box in DMZ, send email to that box and then use como of fetchmail and procmail to trigger script.Can I do something similiar with twitter?e.g. send twitter message from mobile and have some check running on linux box that triggers script.Security is a separate issue, I am just interested in functionality right now.
Answer: It is possible to periodically run a script which grabs your (or a specific) twitter feed
and parses for commands.  The script could then run particular commands based on the contents of the feed.
There are PERL and python modules you could use to parse the twitter feed or various
command line twitter clients which should also work.
The PERL Net::Twitter module could be used to do this.  There are examples of
how to use it in the link.  There are plenty of examples around the web.
A command line program like TTYtter could also be configured and then called from your
script to get the output of your Twitter feed.
hth
Comment: Thank you.Maybe my question was vague.I am aware of perl being a universal glue.I was looking for more specific answers  like module A or module B.
Answer: Ok, I used ttytter in script mode with some perl around it.Seems to do the trick.
Answer: This script is helpful too https://github.com/jalada/twitter-to-omnifocus


Freezing Bouchon Bakery Macarons. Whole cookie or just the halves?

Question: I'm making the macarons from the Bouchon Bakery cookbook and it recommends freezing them for 24 hours before letting them come back to room temperature for eating. The only part I'm not clear on is if I am meant to freeze the whole assembled cookie w/filling or just the cooked halves. If anyone knows what is supposed to be frozen and why I would really appreciate that help..
Comment: The idea that freezing a macaron can make it chewier is indeed not 'hokum'. Freezing many food items changes their texture... Vegetables lose their crisp, bananas become creamy icepops before degenerating into mush, brownies get more fudgy, and macarons become chewier.
Comment: Are you sure it says to freeze them?
Answer: I don't know about the Bouchon recipe, but my wife just attended a macaroon making class at Mille Feuille last weekend.
They recommended refrigerating the whole macaroon overnight (and up to a week), not freezing. The idea is the moisture from the filling migrates to the cookies. This causes the cookie to be moist on the inside, but still have a firm and somewhat crisp outside.
Answer: The text on p.62:

"Once a macaron is finished, its flavor is good, but it will get better. This is why we freeze the macarons (it also makes them chewier and more fun to eat). ....

It sounds like they're freezing the completed macaroon, filling and all.
Answer: I'm getting ready to make my first batch, but I'm interested in these responses.  I currently purchase mine from a reputable local bakery, and when they restock, they bring out plastic trays of macarons that are frozen and wrapped in plastic.  They are delicious, crisp outside, soft, inside, when they thaw.  Hope that helps someone; I'm going to freeze mine with filling.
Answer: I agree with Steve's interpretation of the text he provided. Sounds like the entire thing is being frozen. I can't comment on the reasoning of the author since I've never frozen my macarons whole. But the idea that it makes them chewier sounds like hokum (you don't have to use 'aged' egg whites either).
If you have spare shells you can freeze them in an airtight container for storage. Using a vacuum container may be even better still since you minimise the excess moisture the shells can soak up.
Once assembled, refrigerating in an air tight container should be enough. The shells will absorb some of the moisture from the filling and maybe the flavours too. 1 day is usually enough. You can also salvage overcooked shells this way. If they are too crisp, leave them in the fridge to absorb more moisture.


Roaming user profile issues on Server 2008

Question: I thought I cleared a user's profile from 2008, but it keeps coming back.  So, I was looking for the best way to clear a roaming profile in Server 2008, but I have been unable to find anything.
But, I did see the post here:
User Profile keeps loading TEMP Profile
I wanted to add a comment to that post, but it was closed as not being related to sysadmin.  But, I think it IS related because I dealt with precisely this same problem on our Wndows 2008 terminal server.
Here was the issue:  we have a user who was getting an "unable to load your roaming profile" type of error at logon in Windows 2008.  Looking at the server, we could see her temp profile listed in the profile list while she was loggged (listed as a "temporary" and not a "roaming" profile).  While she was logged on, a folder called C:\Users\Temp.DOMAIN existed in the users folder, but that disappeared as soon as she logged out.
When this thing happened in 2003, we would clear the contents of the roaming profile folder & delete the temp folder in C:\Documents and Settings.  The thing is, 2008 behaves a bit differently.

Server 2008 created a new roaming profile folder in the roaming profile folder share:   \SERVER\ProfileShare\UserName.V2
The local profile disappears from the profile list in System Properties, so there is no profile to clear
Also the local profile folder, C:\Users\Temp.DOMAIN doesn't stay on the server when the user logs out, so we can't delete that as we would normally do when this sort of thing happens in Windows 2003
Despite all of this, every time the user logs back on, the frickin' Temp profile always comes back.

One of my team-mates, who is much more experienced with 2008, said I should check the registry for the user's profile in this key (the users are listed by SID):
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\ProfileList
I saw the user's SID listed there, but it ended in .BAK. I checked several other servers where she is having the same profile errors: in all cases, her SID ended with .BAK.
For example (xxx replacing the LONG SID):
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\S-1-5-21-xxxxx-xxxx.bak
On the server she was logged on to, there were two keys for her profile in the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\S-1-5-21-xxxxx-xxxx
and
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList\S-1-5-21-xxxxx-xxxx.bak
So, here is how I cleared up the issue.

I had the user log off.
I deleted the apparently bad profiles ending in .BAK from the ProfileList key on each server where it appeared.
I made sure her roaming profile folder was empty
I made sure that all the TEMP profile folders were gone
The user logged back on:  no more profile errors!

Anyway, I wanted to make a comment on that closed question, but I didn't see any way to re-open the question so I could add it.
But, I also would like to know if this is the best practice to clear out a bad roaming profile for Server 2008?  I'm having a hard time finding any instructions on line on how best to do this, but this method I used seemed to work.
I'd like to find some documentation to give to our Level 1 support staff so they will know how to clear user profiles on 2008 since this seems to be more involved that clearing user profiles in server 2003.
Thanks,
Alicia
Answer: This how I fix this on 2003 - May help.

Make sure that there are no group policy rules still being applied to that user.
Delete the profile stored locally, as in on the desktop system.
Delete the roaming profile from the network.
Run gpupdate /force on the desktop.
Reboot the desktop.

Log on as the user - The roaming profile should not kick in.
Then add the user to the appropriate OU's and all done :)
Answer: I know its a bit of a delay but to answer your question, from my own investigation into this problem, Yes this is the best way to clear out faulty or broken profiles within Windows 2008 (and R2 btw)
I recently ran into the same problem, and it was a Microsoft Tech Article that documented your process on how to-do this.
Kris


Can one catch up fast of previous years?

Question: I didn't know that you should catch up on any fast you have missed in Ramadan before the next Ramadan arrives. Therefore I have a lot of days to catch up ad I have even lost count of the exact number of days. Can I catch these up before the next Ramadan arrives or will I have to make the payments for not completing fasts?
Comment: I assume the sites below could be profitable for you to read them. http://islamquest.net/ar/archive/question/fa9030 and http://islamquest.net/en/archive/question/fa9411
Comment: you catch up before the next ramzan comes. Payment is for those who cannot fast any more.
Answer: First, I appreciate your keenness to complete the fast, God willing
Sheikh Ibn Baz says in the matter of forgetting the days of fasting following
And the meaning of his words that you have three things:
First repentance to delay fasting.
Secondly, you must fast the days of which you are certain
Thirdly, you have to feed a day for each day of delay if you can afford.
The origin of the fatwa is in Arabic here The source of fatwa
and Allah know
Answer: The ruling on making up missed prayers and fasts, depends on the reason why they were missed. Here is a breakdown and the reason:
❶ - Intentional: If you miss an act of worship intentionally (meaning, you couldn't be bothered, were lazy, were ignorant, so on), then you can not make them up later. The reason for this is that each prayer (fast is similar) is for a particular and defined time (year, day). You cannot arbitrarily choose to perform them at another time because they have been commanded to occur at specific times. Allah is the One who determined when we would fast, and hence we cannot choose to do them at other times by choice (intentional). The known reference, eg, in terms of salah, is:

4:103. إن الصلاة كانت على المؤمنين كتابا موقوتا  ...Verily, the prayer
  is enjoined on the believers at fixed hours.

In such cases, you have to only repent sincerely (with the known conditions of repentance, eg sincerity, not returning to the sin, and so on). Good deeds (eg, voluntary prayers and fasts) is also helpful in repentance.
❷ - Unintentional: If your prayer or fast was missed unintentionally, (eg, you were forced to miss it, you were genuinely tired and asleep or overslept, in battle where the Prophet once or twice prayed later due to it and cursed the disbelievers for keeping them engaged in battle till the correct time passed, etc) - then in SUCH UNINTENTIONAL circumstances, you make up the act of worship as soon as possible. (You can refer to the answer by Tarek or in other places for the penalties of late or unknown fasts/prayers etc in fatawa journals).
If this was due to period and a large amount of time passed without making up the fasts, then:

"She has to ask Allaah for forgiveness and repent to Him, and she has
  to fast the days that she missed and feed one poor person for each
  day, as was stated by a number of the companions of the Prophet (peace
  and blessings of Allaah be upon him). This means giving half a saa',
  which is equivalent to one and a half kilograms." https://islamqa.info/en/40695
Comment: Then all of us should intentionally not pray and just repent cool! But strange logic.
Comment: "And just repent" ? I encourage you to learn the conditions of repentance, the issue of sinning with the intention of repenting, and so on. Also, not everyone has the chance to "just repent" later, even though every single human at the time of death wishes to repent. And not every repentance will be accepted (which is why there are conditions of repentance in the first place). Please understand my answer before raising objections. But I'm happy to clarify.
Comment: Your answer only shows a single view. One can easily do a sin and sincerly repent and redo it it is widely addressed and affirmed in ahadith. The acceptance is something we indeed don't know about as it is in Allah's hands,
Comment: So you expect every answer to show every single view ever brought forward in the history of Islam? My answers are based on proof which I quoted. Not everyone will accept it, and that is not my concern. what you are suggesting, regarding sinning then repenting, does not work when it is intentional, and planning such against Allah is worse. You cannot plan against Allah. "One can easily do a sin and sincerely repent" - IF Allah gives them a chance. And if He gives that chance, then yes, it is good and a mercy upon additional mercy. I think you might be out of your depth in such issues.
Comment: No I just want to point at the fact that this view doesn't sound logical at least not without any explanation. So it was a help to improve your edit. IMO any view is accepted as far is you clearly mention which scholars hold this view. The majority of scholars consider praying qada' necessary in any case as the salat is fard on you so one should regard it as debt, This doesn't mean it will be accepted without repentance.
Comment: I did mention proof. The proof is very clear, EVERY salah and fast is for a set time. You cant just choose to pray it another time or else it wont be accepted. If you cannot understand the proof, you are free to blindly follow some scholar whose view you consider more reasonable. It doesnt change the fact that the acts of worship have a defined time and Will NOT be accepted at any other arbitrarily chosen time. Or else the deen collapses.
Comment: That is the basis of what follows. In that if the salah or fast has a specific time, and you willingly let that time frame elapse, should you be allowed to pray or fast to make that up whenever you want? Does that mean you have fulfilled the conditions of the prayer or fast, of which the time frame is part of the deen? Clearly not. So there is no "making up" such acts of worship, but there is repentance and not returning to the sin, and other conditions of repentance. I hope that is clear now.
Comment: That's an interpretation not a proof. AS other scholars say you should pray missed prayers in their time ... an other interpretation.
Comment: I also said we pray missed prayers.... if they are unintentionally missed. But we will leave the discussion at this point. You are free to disagree if you wish. Guidance cannot be forced, even in the face of clear irrefutable evidence.
Answer: Initially I ought to mention that it is necessary to take the Qazaa  (القضا) of the days which delayed its Qazaa (of Ramadhan) for a year or several years. Secondly it is necessary to point that it should pay one Mod for each day (to poor people (الفقیر)).
Of course you ought to catch them up as you said if I can catch these up before the next Ramadan arrives. But as far as I know, you must pay its Kafarah (الکفاره)  as well as catching them up.

References:
http://islamquest.net/fa/archive/question/fa9030
http://islamquest.net/fa/archive/question/fa47048
http://islamquest.net/fa/archive/question/fa47048
Answer: You should catch up on any fast you have missed in Ramadan before the next Ramadan arrives else you do a payments or buy a food for poor people. there are an amount for each day.
Read this to know why you should not miss any fast
الإعجاز العلمي في فرض الصيام
Comment: Salam and welcome to Islam Stack Exchange. References don't speak for themselves and you cannot expect visitors of an English site to be able to read and understand Arabic, so you'd better elaborate an answer -in your own words- based on the linked article. Please consider taking our tour, checking our help center to learn more about how this site. And read How to Answer to learn what we expect for an answer to be good.


What is the difference between an aeroscraft and an airship?

Question: I stumbled across this site when I was searching for info about airships. They have main three products - aerocraft aeroscraft, airship and aerostat. Aerostat is clear for me somehow. But what is the key difference between aerocraft aeroscraft and airship?
Comment: @mins: Actually the page says _Aeroscraft_; it does not mention it without 's' anywhere.
Answer: Aeroscraft is their brand name. It does not mean anything generally.
The general terms are:
"Aircraft" (but not "aerocraft") means any machine capable of sustained flight in the atmosphere.
"Aerostat" is a lighter-then-air aircraft. That is it has large shell filled with gas with lower density than air and uses buoyant force on that for lift. This includes balloons, hot-air or gas filled, tethered balloons and airships.
"Airship", or "dirigible" is an aerostat equipped with propulsion that allows it to move on it's own (as opposed to balloons that are tethered or carried by wind).
Comment: @FreeMan: No. Hot-air balloon is one kind of aerostat. Hydrogen or helium filled balloons and airships are also aerostats.
Comment: So "Aerostat" is a fancy name for a hot-air balloon?
Comment: Ah, so "Airship"/"Dirigible" is a sub-class of "Aerostat" that indicate they have propulsion and are steerable. I guess that's what your last line says. I'll just go back to napping now... :/
Comment: @FreeMan Balloons and Airships (including Dirigibles) are all aerostats (the term refers to how they stay aloft - *aerostatic buoyancy*). Some may have propulsion (airships), some may be free-flying without propulsion (balloons), and some may be tethered to the ground by cables (tethered balloons). In the US when people refer to "an aerostat" they're frequently referring to some kind of tethered balloon, like the radar balloon off the Florida Keys, but that's an imprecise use of the term.
Answer: There are 2 kinds of lift able to be produced, aerodynamic and aerostatic. Planes and helicopters are aerydynamic because they need to move in order to create the lift, balloons and dirigibles are aerostatic because they create lift by simply being lighter than the air around them. This is why we call them aerostats. I wonder why we don't call the other class aerodynes...


Can I use canola oil to treat cradle cap?

Question: For an 8-month old baby is it safe to use canola oil to treat cradle cap?
Answer: Yes, you can use baby oil or natural oils (almond or olive or canola oil. But avoid groundnut or peanut oil in children under 5.) to loosen thick crusts.  It's probably a good idea to do a "spot test" for allergy.
This is the information I am using for cradle cap.
http://www.nhs.uk/conditions/cradle-cap/Pages/Introduction.aspx
It's a harmless condition; it usually clears itself after a few months; most cases have completely gone by the age of one year.  If baby is scratching or appears distressed by cradle cap it's probably a good idea to ask a doctor or health visitor because it might not be cradle cap.
Comment: I found your link and - interestingly - a contradiction from the other side if the pond. The [Mayo Clinic](http://www.mayoclinic.org/diseases-conditions/cradle-cap/basics/lifestyle-home-remedies/con-20032328) and other US sources recommend mineral oils or petroleum jelly where GB sources advocate natural oils. My gut feeling would lead me to almond oil or similar, I avoid mineral oils whenever possible, but that's not based on scientific research.
Comment: @Stephie - that's interesting! I'd be intersted to see why they recommend different oils. Does anyone know?
Comment: @DanBeale a quick Googling leads to some sites saying veg/nut oils can increase the risk of an associated yeast infection, but that is the limit of what I have time to research right now.
Answer: Sure, canola oil is fine to use on the baby's scalp.
For cradle cap, you can rub any edible non-nut vegetable oil into the crusted areas, but don't leave it on for hours; wash it off with baby shampoo 5-15 minutes after applying, and brush the flakes of crust off with a baby hairbrush. Repeat every day until gone, then shampoo hair at least twice a week.
I'm concerned, though, that at this age, it might not be simple cradle cap (it is more common in early infancy.)
If your baby hasn't been to their doctor for this, you should take them (it's not an emergency, though.) If it's not cradle cap, it will be treated differently. The baby should have a thorough skin exam for other affected areas, and a differential diagnosis should be considered. If it is cradle cap, there are now good new treatments for it.
The Frequency of Common Skin Conditions in Preschool-aged Children in Australia: Seborrheic Dermatitis and Pityriasis Capitis (Cradle Cap)
Comment: Well it could still be left overs, ours still has a bit that she didn't get to scratch off.
Answer: As mentioned, you probably want to test for allergies first, this one requires more care but hands down the best thing I found was to take a dry flannel and put about half a teaspoon of 100% tea-tree oil on a small area near the corner of the flannel, then use the flannel to carefully work the tea-tree into the scales. Keep the dry end of the flannel handy to control any loose oil, but try not to use so much oil that you cause any drips.
This oil dissolves the scales right away, no matter how bad it's gotten. Then just carefully wash the gunk and tea-tree out of the hair afterwards, keeping the water away from the face with another dry flannel. I've used this technique many times and never had any incidents, but if you're not confident in safe application of this oil, I probably wouldn't recommend for babies or kids that can't keep still. The fumes alone can be overwhelming if you use too much. If you do it right though, it's a ten minute job with perfect results.
Answer: Canola oil would be safe as long as there isn't an allergy. I have heard that mineral oil is the best, but we used olive oil. I don't know that it makes a ton of difference which kind. What seemed to be more effective was when we followed up by brushing the scalp with a bristle brush, and we had to make sure and do it every day. Cradle cap can be really hard to get rid of.
I recommend rubbing the oil into the scalp, then use a bristle brush to gently break up the scales and wash it out with shampoo.
Comment: Hi, Gina, and welcome! We usually don't endorse particular products on this site, especially when the OP is not asking for a product recommendation. Such links might be flagged as spam. I edited out the link, sorry. I'm glad it worked for you, though.


How can I unlock an iPhone 4 without the original receipt? (UK)

Question: My friend sold me his old iPhone because mine got stolen and he didn't need his any more. However, in order to unlock it so I can use my O2 sim, his network (3mobile) require the original receipt for the handset. He doesn't have it, so they refuse to unlock it. What are my options?
Answer: Three UK will provide unlocking for a device on payment of a fee. The requirement of the sales receipt may be their attempt at a fraud/theft prevention mechanism to make sure that stolen phones cannot be unlocked and reused.
If your friend purchased the device from 3 then he should be able to verify identity with them through payment history, and enable the route to unlocking the device.
When unlocked you will not receive and unlock code like some devices, instead the identity of the phone is passed to the Apple activation servers so then next time the device connects for activation it receives the unlock command.
Answer: 3mobile has no obligation to unlock this device without the receipt (or whatever other terms they stipulate). Your best option is to search on eBay for someone who will unlock a device from 3mobile. You should be able to find a solution for under $10.
Answer: Have a look:
http://iclarified.com/unlock/index.php (unlocking)
and
http://iclarified.com/jailbreak/index.php (jailbreaking)


How to understand influenza strain designations?

Question: What do the strain designations for flu mean?
For example avian flu is classified as H5N1, what do the letters H, N and numbers 5, 1 mean? Is it more than a simple string-identifier?
Answer: The sub-type is named for the broad classes of the hemagglutinin (HA) or neuraminidase (NA) surface proteins sticking through the viral envelope. There are 16 HA sub-types (designated H1 - H16) and 9 NA sub-types (designated N1 - N9). All of the possible combinations of these influenza A subtypes infect birds, but only those containing the H1, H2, H3, H5, H7 and H9 and the N1, N2 and N7 surface proteins infect humans, and of these, so far, only H1, H2, H3 and N1 and N2 do so to any extent.
Read more: http://www.fluwiki.info/pmwiki.php?n=Science.NamingInfluenzaViruses
Answer: Subtype is denoted using the HxNy notation for the variant of hemagglutinin and neuraminidase.
Strain names are specified as: [virus type]/[location of origin]/[sequential number of isolation]/[year of isolation] ([subtype]), such as "A/Alabama/AF2070/2010(H1N1)"

Virus type would be A, B, or C for the various forms of influenza (influenza A being the most common among humans)
Location can be a country, state or city (e.g. Laos, Alabama, or Moscow)
The number of isolation can be a simple number, but sometimes it goes beyond; e.g. "AF2060" or "UR06-0455", possibly due to the tremendous number sequenced nowadays.
Year, obvious.
The subtype refers to the aforementioned HA/NA subtype.

Many more strains can be found on the Influenza Research Database.
Answer: The two letters represent the type of hemagglutinin (H) and neuraminidase (N) present on the viral surface. Those are the major surface proteins of the influenza virus and therefore crucial for the immune response.
From Immunology and Evolution of Infectious Disease

HA and NA reactivities with antibodies define the subtypes of
  influenza A (Cox and Subbarao 2000). Fifteen different HA antigenic
  subtypes occur, each subtype cross-reacting relatively little with the
  other subtypes. Nine distinct NA subtypes are known. The designation
  HxNy describes an influenza subtype with HA antigenic subtype x =
  1,...,15 and NA antigenic subtype y = 1,...,9.

The numbers represent different subtypes of the hemagglutinin and neuraminidase proteins.
Answer: Adding to the other answers posted:
Hemagglutinin  (HA or H) -  Helps the virus enter the cell by binding to sialic acid receptors on cell membrane. It then unfolds in a lysosome and fuses the viral and lysosome membranes.
Neuraminidase (NA or N) - Helps the virus exit the cell by cleaving the terminal sialic acid residues at the progeny virus release.


Does the president of the USA have free will?

Question: I don't remember where but I saw a chazal that states something to the effect of "the (non-Jewish) leaders of the world do not have free will".
I would appreciate someone editing to source this.
So I am wondering A) Does the President have free will
and B) If not then does it matter who we vote for? (Even if we have a chiyuv of hishtadlus, I am asking if the choice will ultimately be effective)
I would like to stay away from the fundamental discussions of bechira that underlay my questions and stick with this particular point.
Thanks!
Comment: mishlei 21:1 א  פַּלְגֵי-מַיִם לֶב-מֶלֶךְ, בְּיַד-יְהוָה;    עַל-כָּל-אֲשֶׁר יַחְפֹּץ יַטֶּנּוּ. 1 The king's heart is in the hand of the LORD as the watercourses: He turneth it whithersoever He will.
Comment: Although that opinion may exist (unsure if it does), there's certainly an opinion that G-d hardening Pharaoh's heart meant strengthening Pharaoh's free will. Thus, Pharaoh had free will and if Pharaoh, then kal v'chomer the US president.
Comment: I think that I understand your point. However I could argue that according to Rav Desslers famous explanation of the "point of free will" (i.e. that your ability to make a real bechira choice exists only at a certain point and everything easier or harder is not in your realm of choice) Hashem hardened Paroh's heart in order to keep him from choosing the easy option of not letting Bnei Yisrael go (or to keep him from choosing at all) in order for Yetzias Mitzrayim to happen the way it did. This might have been a one time occurrence for a very specific goal.
Comment: @Gabi my point was that although you may be able to find an opinion that the US President doesn't have free will, you also have a source on Paroh davka having free will.  If G-d could let Paroh have free will, when yetziat Mitzrayim is such a big deal, that opinion should kal v'chomer hold that the US President has free will. Are you specifically looking for a justification not to care about voting?
Comment: @Charles Koppelman Got it,I understand your point now.
I'm not looking for a justification (as I said in my post we [could] have a chiyuv of hishtadlus regardless of the mechanics of how free will plays out in this case.)
Comment: rabbi mendel weinbach brings this down here also
http://ohr.edu/5256
Answer: The famous saying that you are thinking of is לב שרים ביד השם. Unfortunately this saying is not from Tanach, rather it is an adaption of the Posuk in Mishlei 21:1 לב מלך ביד השם.
This is generally understood that leaders do not have free choice on things that affect their subjects, rather God decides that himself and sways the Kings heart. For more of a discussion of this and about King Pharoah, see this Aish article which discusses this at length.
As for whether the President has free will, it follows that on things like Iran which would affect millions of citizens, he does not have free will. The Aish article seems to imply that by doing the right Hishtadlus and voting for the right person, God sways that leaders heart to the Good!


Working for an English company , moving to Italy as home based. What's the best way to avoid too many taxes?

Question:
becoming an italian consultant (independent contractor) i.e. invoicing the UK company monthly in order to pay taxes in Italy only.
keeping the contract in UK as employee and pay double taxes. If so how to proceed with that considering the Brexit? who to refer to to apply for the double taxation?
Answer: If you want to pay low amounts of tax, you are probably in the wrong country.
Realistically, especially post-brexit, you probably need to invoice through a company. There is a corporate tax rate of 31.4%, and a dividend tax rate of 26%. That means for every 100 euros you bill, you will receive 50.76 of them, assuming you don't write off any expenses.
You can remain an employee of the company, but I am almost certain they would need to register to pay tax in Italy, and they would have to pay things like payroll tax. Dependent on how Brexit happens that may or may not continue to be possible. You touched on paying UK tax, and while if you company was requiring you to work abroad you could have some number of years continuing to pay UK social contributions, and UK tax, this would expire and isn't really relevant to your situation.


What did you use to teach scale drawings?

Question: I need help finding a way to teach the standard of reproducing a scale drawing at a different scale for my 7th grade math class.
Comment: If this is their first time with scaling, I would start with quad (graph) paper and colored pencils. You could also supplement it with some basic number theory for brighter students.
Answer: An important concept in scaling figures at this level is the connection to proportionality (which is obvious to many advanced math users, but is not obvious to many students and even teachers).
It's unclear what sort of activity you're thinking about. I have produced Geometer's Sketchpad sketches that are used with Sketch Explorer on the iPad, and these sketches were used as dynamic activities in interview items as part of a study of 6th and 7th grade math teachers' knowledge of concepts of proportion, scale, fraction, and ratio. I have found that, while constant of proportionality is obviously an important concept in understanding the relationship between similar but differently-scaled drawings, this is not used as commonly as one would expect.
Therefore, it might be useful to your students to manually construct scaled drawings (construct drawing B from drawing A), determining a constant of proportionality in the relationship between the corresponding linear measures. Even 7th grade students may be surprised that there is a constant relationship in all the corresponding linear measures (including widths, heights, perimeters, circumferences, etc). Once this relationship is discovered / understood, any scaled drawing can be reproduced. Angles need not be measured; any point in the scaled drawing can be located by finding its horizontal and vertical distances from the nearest sides.
Cheers!


Why did Gilgamesh remain in the human world?

Question: I actually didn't understand why did Gilgamesh remain in the human world. What I understand is that he touched the Grail that's why he remains.
Comment: Because he's a king of kings you FILTHY MONGREL :D
Comment: I believe he stuck around just because he was never killed and Kirei kept supplying him with mana so they could do a scheme together in the next Grail War. I'm sure one of our many Fate series experts will be along soon to explain all the convoluted intricacies of the situation, though.
Comment: SHort version, he wanted another shot at the Grail, and there was no guarantee he'd be summoned again for the FIfth War.  The fake priest was down with it, so they tried.
Answer: Initially, it's stated that servants are kept in the world by the Holy Grail. (This comes up in the Good End of "Unlimited Blade Works," but I imagine this piece of information might have appeared earlier.) They also need a mana supply; note also that servants who had become separated from their masters in Fate/stay night did not immediately disappear. In the case of Gilgamesh, both of these conditions were fulfilled. The Holy Grail was still around, and Kotomine kept the orphans from the fire under the church and used them as a mana source.
In the events of Fate/stay night, other servants were also retained, even when the Grail was destroyed. In the "Good End" of the "Unlimited Blade Works" route, Saber stays in the human world. Rin has been supplying mana to her, and she asks Shirou to help her. Similarly, in the "True End" of "Heaven's Feel", Rider stays with Sakura even after the destruction of the Grail; per the wiki, this is possible because Sakura has enough mana reserves because of her connection to Akasha.
The Wikia also gives an explanation of what happened to Gilgamesh at the end of Fate/zero. (I cannot provide much more commentary on this, since I haven't followed the series lately.)

Due to his proximity, Gilgamesh is caught off guard and becomes drenched by the pollution that spills from the Holy Grail. He obtains a physical body, and because he has been incarnated into the world, he decides that it is time to once again unite the world under his rule. He continues to follow Kotomine after the war is over, and Kotomine provides him with energy drained from children orphaned by the fire to sustain himself. He decides to wait for the next Holy Grail War to cleanse humanity, so he retrieves a potion of temporary youth from his vault that reduces his physical age and allows him to smoothly blend in with society for ten years.
Comment: Seems good to me.  The last part is fairly important.  The possession of a physical body substantially lowers his energy requirement, as he no longer needs energy just to exist.  The youthful form further reduced his energy needs.

The servants are likened to extremely powerful familiars in the game, requiring magical energy well in excess of all but the greatest mages.  Rin's two endings point this out: without Saber she joins the Clock Tower; with her she doesn't because she is (1) way too big a target with such an awesome familiar and (2) unable to use much magic because it goes to Saber.
Comment: If I've gotten something wrong or I'm missing something, please comment, and I'll either edit or delete my answer.


Is there a Christian sect that believes only The New Testament and only Christ is God and The Whole Trinity exists in Him?

Question: "For in him dwelleth all the fulness of the Godhead bodily." - Colossians 2:9
Comment: I'm not here to argue theology with you, I'm asking if there is a Christian sect with those beliefs (whether they are correct or wrong). By the way, I find it interesting that I got two votes down so far just for asking a question, even though it's just a question without any claims nor errors about facts or truth. People are voting with biases of their personal emotions rather than with reason.
Comment: [Cathars](https://christianity.stackexchange.com/q/43483/1787) rejected the Old Testament.
Comment: @God_Is_Love For the record, I am not a contributor to abovementioned downvotes; I tend to seek clarification before I decide the question is unworthy of the site—I'm still unclear as to what you mean when you say, "only the New Testament." There is no New Testament which does not import the entirety of the Old Testament. Clarification is needed.
Comment: You mean only the Bible? The New Testament constantly references the Old Testament—it is the Old Testament which is the referent of the word "the scriptures" in the New Testament! Also, according to Trinitarian theology, the fullness of the Godhead is in each person of the Trinity; it doesn't mean for Christ to have the fullness of the divinity in Him that He must be all three persons of the Trinity.
Comment: I'm not sure why some are voting to close this question based on "unclear what you're asking". It's clear to me.
Answer: I have heard of a denomination that believes only the four gospel accounts in the New Testament, but cannot find the source.  I am unaware of any denomination that believes in only the New Testament.  From an answer you posted previously you said:

Jesus revealed The Merciful Heavenly Father through His Teachings in the clearest way while The Old Testament did not, therefore we can go with sola scriptura when it comes to The Sayings of Jesus. Even then, sola fide must come first since a person must first believe that Jesus is The True Voice that reveals God The Father in order to trust His Teachings in The Gospel: "All things are delivered to me of my Father: and no man knoweth who the Son is, but the Father; and who the Father is, but the Son, and he to whom the Son will reveal him." (Luke 10:22) Source: What was first, sola scriptura or sola fide?

However, with regard to a denomination that believes only Christ is God, then I would suggest Oneness Pentecostals.

Oneness Pentecostals believe that there is but one God, a singular divine Spirit, who manifests himself as Father, Son, and Holy Spirit. This one indivisible God has no distinction of persons in God's eternal essence, and Jesus Christ is the manifestation, human personification, or incarnation of the one God.  Source: https://en.wikipedia.org/wiki/Oneness_Pentecostalism

The United Pentecostal Church International, the largest Oneness Pentecostal denomination, says there is one God, who has revealed Himself as the Father, in His Son Jesus Christ, and as the Holy Spirit.  Jesus Christ is God manifested in flesh. He is both God and man.

Oneness believers hold that God is absolutely and indivisibly one (Deuteronomy 6:4), and do not accept the idea of three distinct centers of consciousness in the Godhead. They also affirm that in Jesus dwells all the fullness of the Godhead bodily and that Jesus is the only name given for salvation (Colossians 2:9). The Father was revealed to the world in the name of Jesus, the Son was given the name of Jesus at birth, and the Holy Spirit comes to believers in the name of Jesus. Thus they believe the apostles correctly fulfilled Christ's command to baptize "in the name [singular] of the Father, and of the Son, and of the Holy Ghost" by baptizing all converts with the invocation of the name of Jesus (Matthew 28:19; Acts 2:38; 8:16; 10:48; 19:5; 22:16).
Oneness believers affirm that God has revealed Himself as Father (in parental relationship to humanity), in the Son (in human flesh), and as the Holy Spirit (in spiritual action). They acknowledge that the one God existed as Father, Word, and Holy Spirit before His incarnation as Jesus Christ, the Son of God; and that while Jesus walked on earth as God Himself incarnate, the Spirit of God continued to be omnipresent.  Source: https://en.wikipedia.org/wiki/United_Pentecostal_Church_International#Godhead
Comment: What about believing that there aren't different modes of God but that The Three all exist eternally as One? The Father as The Eternal Mind of God, The Son as The Eternal Image of God and The Holy Spirit as The Eternal Spirit of God, all existing in One Eternal God, Christ, and that we were made in His Image with Mind and Body and Spirit.
Comment: What about it? You asked if there was a Christian sect that believes only Christ is God and the whole Trinity exists in Him.  As far as I can see, I've answered your question. My personal opinions on the Jesus Only Oneness Pentecostal views about the Trinity have nothing to do with anything. Personal opinions are not encouraged on Christianity Stack.
Comment: You did answer the question, then I asked if there is a sect that isn't moralistic. The hostility isn't necessary.
Comment: Sorry, but you've completely lost me with your last comment saying you asked "if there is a sect that isn't moralistic". And I'm not being hostile and I did not down-vote your question. I'm afraid I simply don't understand what you are now asking.
Comment: Not moralistic but modalistic. Sorry, I couldn't edit the post. I was thinking about a non-modalistic belief in Jesus Christ as the one God. A belief that only Christ is God and The Holy Trinity is revealed and exists within Him.
Comment: Okay, I'm with you now! However, the subject of modalism and those who oppose it  has probably already been covered in detail elsewhere on Christianity Stack.  I will take a look and see if I can find anything....
Comment: Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/97305/discussion-between-lesley-and-god-is-love).


What case after "с"?

Question: I read the phrase начать с дерева in the context of a young man wanting to change his life and deciding to start by planting a tree.
Why is дерева in the genitive case, while I would have expected the instrumental?
A grammar book of mine indeed indicates that с can be followed by a genitive or an instrumental, but is there a rule telling which to choose?
Or should I just learn for each possible combination verb+с what the correct case is?
Comment: Phrases involving с + genitive that are useful: (1) с этой точки зрения ("from this point of view"), (2) с одной стороны ... с другой стороны ("on the one hand... on the other hand," or literally "from one hand... from the other hand"), (3) начиная с девятнадцатого века ("starting in the 19th century", or literally "starting from the 19th century").
Comment: *Or should I just learn for each possible combination verb+с what the correct case is?* < this.
Answer: With instrumental, с means "with". With genitive, с means "from" or "off" — that is, moving away from a thing's surface (as opposed to из which is for moving away from inside a thing). You take a thing "off" a shelf (с полки) but "from" a cupboard (из шкафа). For all intents and purposes, this с is a different preposition than the one meaning "with".
Among the more abstract meanings of с+genitive, the most common one is "beginning with", "from X onwards", or "since" when talking about time. Now of course, with prepositions used abstractly it's not always easy to figure out the underlying metaphor; начать с дерева is, literally, to "start from a tree" rather than with a tree, whereas in English one more commonly begins/starts "with" things. There's no particular reason why it's one or the other (or something else entirely); so I suppose with some verbs, you just have to learn it.
Still, you might want to first try and see if you can follow the logic behind which с it is; there are many cases where, abstract or not, that logic is plain enough, e.g. in взыскать с должника, it's clear that the debt is collected "from" someone rather than "with" them — whereas in расплатиться с кредитором, it makes mor sense to say that a debt are settled "with" a lender rather than "from" them.
Comment: **От** is for either leaving the vicinity of a thing, or becoming a breakaway part of it. Prepositions of to/from motion can be rather neatly arranged in pairs: **из** is the inverse of **в** (the accusative one, "into"), **с** (+genitive) is the inverse of **на** (+accusative), and  **от** is the inverse of **к**. A letter from someone is **письмо от** — but note that a letter from *someplace* is **письмо из** (or, occasionally, **письмо с**).
Comment: Thank you for your (as usual) crystal-clear comment, dear Nikolay. I am really amazed by your linguistic and didactical talent. May I take the liberty to ask what your mother tongue is? [ I'm curious because usually people are not so good at explaining the whys and wherefores of their native language since everything seems so natural to them :-)]
Comment: While we are at it, could you please also explain when *от* is used for translating *from* ?
Comment: Glad to hear that :) My mother tongue is Russian; my mother, however, was a translator from Czech and Polish, so already the lullabies and nursery rhymes I grew up with were in several different, but not completely different, languages — and that I suppose was where it all began.
Comment: Thanks again for your supplementary  explanations, Nikolay (and the fragment of your autobiography!).
Comment: You say с + genitive for movement means "away from a surface." I had learned that this is the meaning of от + genitive, for instance the movement of a rocket is от земли, not с земли. How does this fit your explanation of the distinction between с and от?
Comment: @KCd I can only think of one case when you'd say **от земли** about a rocket; it's with the verb **оторваться**. For all others, such as **подняться** or **запустить**, it's definitely **с**. Are you sure you're not mixing them up?
Comment: Now that I think more closely, I was imagining not movement but location, e.g., рассотяние ракета от земли.
Answer:
начать с дерева = start from a/the tree
начать с деревом = start having a/the tree
Answer:
с + instr. = "with"
с + gen. = "from" (more or less, for some meanings of "from")

Others have already given more precise answers about the above, so I will just mention the fairly rare
с + acc.
which is used in sentences like
размером с морскую свинку = about the size of a guinea pig
размером с тыкву = roughly as big as a pumpkin
Answer: С can be followed by genitive, accusative or instrumental, but it's not the preposition which governs the case of a complement, it's the verb or noun it completes.
Начать с + gen. literally means "start from (the top of) the tree", the preposition c here being used in the sense "from the top of", as opposed to из "from the inside of" and от "from the proximity of".
This verb governs с + gen. in the same way жить, брать and even смеяться and бить in some dialects do: брать с него долг, жить с нетрудовых доходов, **смеяться с клоуна, **бить с локтя. It's just how these verbs work.
The last two examples are dialectal and sound quite peculiar to those not used to them, but totally OK to those who are.

What case after "с"?


Request theorem/Proof for $F(x)>0$ for $a<x<b$

Question: Suppose
$$
F(a)=0, F(b)=0, a<b
$$
and
$F''(x)<0$ for $a<x<b$.
Do we have $F(x) > 0$ for $a<x<b$?
Can you tell me an existing theorem that I can use in a paper to obtain the conclusion? I think there should be one, but I can't remember.
Comment: If $F(x) < 0$ for some $a < x < b$, then you can use the mean value theorem three times to show that $F''(X) > 0$ somewhere.
Comment: @arkeet I mean, can you tell me an existing theorem that I can use in a paper to obtain the conclusion? I think there should be one, but I can't remember.
Answer: This is a consequence of the convexity of $-F(x)$ on $[a,b]$.
Suppose $F(c) < 0$ for some $c \in (a,b)$.    By the mean value theorem, there exist values $d_1 \in (a,c)$ and $d_2 \in (c,b)$ such that
\begin{align}
F'(d_1) = \frac{F(c) - F(a)}{c - a} = \frac{F(c)}{b-a} < 0
\\
~
\\
F'(d_2) = \frac{F(b) - F(c)}{b - c} = \frac{-F(c)}{c-b}> 0,
\end{align}
and hence $F'(x)$ changes sign somewhere on $(a,b)$.  This contradicts $F''(x) < 0$.  Hence, $F(c) \geq 0$ for all $c \in (a,b)$.
Answer: Why not. can be concave/not and positive between any two points. the concavity of the curve may also be changing at x. Depends on the function.
Answer: There is no theorem that I know of that talks specifically about this case, but you can prove it using a bit of simple calculus.
How about this proof: By Rolle's theorem, $F'(x) = 0$ at least once in the interval $(a, b)$. However it must happen exactly once since $F''(x) < 0$... This critical point is a maximum point, so we have $F(x)$ ascending from $(a, 0)$ towards a maximum and then descending back to $(b, 0)$.