RTOS vs Linux against single event upsets

Question: I am working on the on-board computer for a CubeSat. Our computer will be vulnerable to radiation, hence single event upsets, e.g. bit flips are likely to occur. Would a lighter, smaller OS like FreeRTOS bring more stability and a lower probability of failure over a full-blown Linux operating system?
Comment: Or it shouldn't be migrated, since the topic is unique to a space application.
Comment: @GdD: I'm not entirely sure SU would have any more expertise in the area of avionics OS selection.
Comment: If anything, this would be a question for electronics, not SU. But I think it fits perfectly well here.
Comment: This should be migrated to superuser.stackexchange.com
Answer: In general, you want as simple of an OS for any embedded systems application. You want as few features as you can get away with. You are less likely to run into problems that way, don't really need all of the features, and it'll reboot quicker, and use less memory.
Two things you want for sure. You want a realtime operating system, you probably want threads and similar protections, but you probably don't want device drivers, for instance, especially for GUIs. Rodos is one OS I found in my search that meets the criteria, I'm sure there are others. RTOS is a reasonable choice as well.
BTW, as a bonus tip, there are several architectures used to keep satellites safe in case of an emergency. See How does one build software for a Satellite such that a new build doesn't break it? , for instance.
Answer: I don't know about the probability, but the RTOS will reboot a lot faster. When you run into a problem, and you will run into a problem, you reboot, and you want that to be fast.
Answer: I do know that FreeRTOS, on an Pumpkin MSP430-F216 microprocessor platform, has been working successfully on the NASA Firefly Cubesat project that I wrote the flight and ground software for, and has been communicating for over 2 years.


Shouldn't I kill even mosquitoes that bite me by first precept?

Question: By first precept I shouldn't kill even a mosquito it bite me but when as by 7th precept I can listen music for therapy If things fall into such circumstances like this mosquito biting can lead me to malaria or dengue. Also I've to ask if I can consume yogurt when it's made with help of bacterias they are also living being. I don't mean I'm trying to find breaking precepts,but I stopped killing them really.
Answer: The 1st precept is a training rule to refrain from killing 'breathing' things.
The Pali is: "Panatipata veramani sikkhapadam samadiyami", where the word "pana" means "life" or 'breath", such as in the term "ana-pana-sati".
The 1st precept does not apply to bacteria because they do not breathe.

Strictly speaking, bacteria do not "breathe" as humans and other animals do, but they must still engage in the act of cellular
respiration. Cellular respiration is the method by which cells convert
chemicals into energy that the cell needs to stay alive.
Bacteria

As for mosquitoes, the probability of contracting malaria or dengue fever is very low. I lived in Thailand for 9 years and had dengue fever only once. I can contract dengue fever where I have lived for the last 10 years & have never got it (although one friend did). When I lived in Thailand, there was a period of a few years when hundreds of mosquitoes would bite my feet when I was meditating at sunset. I never got dengue fever or malaria during this period. I felt very free when my mind became accustomed to not worrying about & fearing mosquitoes.
Not killing mosquitoes is beneficial for cultivating metta (loving-kindness), fearlessness & freedom. However, that said, killing mosquitoes is not particularly bad karma. When I first visited Thailand & learned meditation, I did not care about killing mosquitoes & killing a mosquito never affected my samatha (calmness; concentration) meditation. This is because killing a mosquito is kammically a natural act. The mosquito wants to steal our blood & can (possibly) kill us. This is why the kammic results (vipaka) of killing a mosquito are trifling (insignificant).
Most people have killed many mosquitoes & remain mentally normal. Their minds do not become deranged (crazy). Where as the majority of soldiers that kill in war are often mentally affected for life in a negative way. Some ex-soldiers become mentally deranged & even commit suicide. (Here, an ex-soldier must learn to forgive themselves!) This shows the difference between killing many mosquitoes & killing just one or even many human being/s. Kammic consequences (vipaka) follow the law of nature.
The Buddha taught "kamma is intention" (AN 6.63). A mosquito killed with the intention of avoiding malaria or dengue fever is not an unwholesome intention. However, it is still an intention rooted in fear, attachment & a lack of liberation.
For example, to kill a mosquito so it does not bite a small baby or child is probably good karma. If it was known you let mosquitoes bite your small baby, many people would criticize you. You would be blamed & censured for being a bad parent. The government may take your child away from you.
Personally, I would not worry too much about it since not killing mosquitoes is a higher level of dhamma practise. The Buddha did not make strict rules for monks about killing mosquitoes or even about killing animals (for food) for laypeople.

And which is intolerant practice? There is the case where a certain individual doesn't tolerate cold, heat, hunger, & thirst; the touch of
flies, mosquitoes, wind, sun & reptiles; ill-spoken, unwelcome words;
& bodily feelings that, when they arise, are painful, racking, sharp,
piercing, disagreeable, displeasing & menacing to life. This is called
intolerant practice.
And which is tolerant practice? There is the case where a certain individual tolerates cold, heat, hunger, & thirst; the touch of flies,
mosquitoes, wind, sun & reptiles; ill-spoken, unwelcome words; &
bodily feelings that, when they arise, are painful, racking, sharp,
piercing, disagreeable, displeasing & menacing to life. This is called
tolerant practice.
Khama Sutta
Answer: I think the formula is actually I will restrain from the killing of sentient beeings. Keep in mind that the 5 precepts are not obligations, but rather rules you take up voluntarily. Nobody forces you to keep them, but they are an absolute minimum of Buddhist morality. The mind that has the intention of killing, stealing... is not able to have a clear perception of reality, at all.
Comment: I would just like to say, that the desire to kill something, and then the act of killing, if done so in an act of hatred or anger, is something which will cause great issues for the person, even if it has minimal affect on the being being killed.
Answer: Questions about killing insects have appeared a few times here, I suggest reading them:

Is killing vermin and insects justifiable?
What does Buddhism say about intentionally killing dangerous insects and beings?

While some may dispute whether or not the precept apply to insects or whether they are sentient beings, in general, deliberately killing a mosquito is considered akusala (unwholesome) action, rooted in dosa (aversion, ill will, hatred) / moha (ignorance).
As for traditions, I've heard Zen, Theravada and Tibetan monks teaching to regard insects to be living beings and they may consider intentionally killing them to be breaking the precept.
In one answer from the questions linked above, Bhikkhu yuttadhammo writes:

Even if killing a single mosquito would end all cases of malaria in the world for ever, the (Theravada) Buddhist philosophy would be to abstain from killing the mosquito.

For more information from the Theravada point of view, check this text by Bhikkhu Bodhi on the precepts, The first precept: abstinence from taking life.
Now, on your question, killing a mosquito because it may threaten you may be justified if you regard it as a living being. Is killing it the only way to preserve oneself? Sometimes one can simply stay away, isolate oneself from it, os just go somewhere else. That's, I think, the general teaching to avoid breaking the precept to save oneself from harm: try to get away from danger without causing you and others harm, with a mind inclined to non-harm.
As for bacterias, I'm not so sure one is killing them by eating yogurt. Eating yogurt with the intention to kill them, however, would likely be worrisome.
But in general, I think buddhism is silent regarding micro-organisms and most traditions seem to consider an act of killing by the intention to kill (thus, deaths caused accidentally are not considered such acts).
Comment: Kill a human,kill a fish,kill a mosquito, eat a yogurt with microbes in it and eat a plant. all are life forms. intentions are taking revenge with intensive hate, as a food for your survival or just for craving of taste of fish, just to escape from diseases, not with intention to kill just intake food, no intention to kill. you are right ,intention is most important. In first precept ; five conditions must be completed to commit a kill.  1. awareness of object is living being 2. intention of killing 3. implement method to kill 4. use the implemented method to kill 4. life is terminated.
Answer: No, you should not even kill mosquitoes that bite you, according to the First Noble Precept.
Answer: From Bhikkhu Bodhi's discussion on the first precept, we find some comments on the varying gravity of the kamma of killing:

The first distinction given is that between killing beings with moral
  qualities (guna) and killing beings without moral qualities. For all
  practical purposes the former are human beings, the latter animals,
  and it is held that to kill a fellow human being is a more serious
  matter ethically than to kill an animal. Then within each category
  further distinctions are drawn. In the case of animals the degree of
  moral gravity is said to be proportional to the animal, to kill a
  larger animal being more blameworthy than to kill a smaller one. Other
  factors relevant to determining moral weight are whether the animal
  has an owner or is ownerless, whether it is domestic or wild, and
  whether it has a gentle or a vicious temperament. The moral gravity
  would be greater in the former three alternatives, less in the latter
  three. In the killing of human beings the degree of moral blame
  depends on the personal qualities of the victim, to kill a person of
  superior spiritual stature or one's personal benefactors being more
  blameworthy than to kill a less developed person or one unrelated to
  oneself. The three cases of killing selected as the most culpable are
  matricide, parricide, and the murder of an arahant, a fully purified
  saint.

The five precepts are training rules and not strong prohibitions.
Furthermore, even for monks, based on the Patimokkha rules, intentionally bringing about the death of a human being is a parajika offense, while taking the life of an animal is a pacittiya offense. A parajika offense is the gravest offense causing immediate expulsion, but a pacittiya offense is milder, requiring only a confession.

Parajika Rule 3. Should any bhikkhu intentionally deprive a human
  being of life, or search for an assassin for him, or praise the
  advantages of death, or incite him to die (saying,): "My good man,
  what use is this evil, miserable life to you? Death would be better
  for you than life," or with such an idea in mind, such a purpose in
  mind, should in various ways praise the advantages of death or incite
  him to die, he also is defeated and no longer in affiliation.
Pacittiya Rule 61. Should any bhikkhu intentionally deprive an animal
  of life, it is to be confessed.

And also on the motivation for killing (from here):

Another factor determinative of moral weight is the motivation of the
  act. This leads to a distinction between premeditated murder and
  impulsive killing. The former is murder in cold blood, intended and
  planned in advance, driven either by strong greed or strong hatred.
  The latter is killing which is not planned in advance, as when one
  person kills another in a fit of rage or in self-defense. Generally,
  premeditated murder is regarded as a graver transgression than
  impulsive killing, and the motivation of hatred as more blameworthy
  than the motivation of greed. The presence of cruelty and the
  obtaining of sadistic pleasure from the act further increase its moral
  weight.

In my opinion, if rulers, government officials, neighbourhood resident associations and even individuals decide to kill mosquitoes and mosquito larvae due to a proven rising dengue or malaria epidemic, it would be a reasonably justifiable motivation for killing. After all, isn't it wrong to endanger fellow humans knowingly?
From the Lonaphala Sutta:

"Now, a trifling evil deed done by what sort of individual takes him
  to hell? There is the case where a certain individual is undeveloped
  in [contemplating] the body, undeveloped in virtue, undeveloped in
  mind, undeveloped in discernment: restricted, small-hearted, dwelling
  with suffering. A trifling evil deed done by this sort of individual
  takes him to hell.
"Now, a trifling evil deed done by what sort of individual is
  experienced in the here & now, and for the most part barely appears
  for a moment? There is the case where a certain individual is
  developed in [contemplating] the body, developed in virtue, developed
  in mind, developed in discernment: unrestricted, large-hearted,
  dwelling with the immeasurable. A trifling evil deed done by this
  sort of individual is experienced in the here & now, and for the most
  part barely appears for a moment.

I take the killing of mosquitoes and mosquito larvae with the motivation of dengue or malaria eradication, to be a trifling evil deed, and if we do it with the correct motivation and the correct state of mind, then it is acceptable although not ideal. The same applies to rats and diseases spread by rats like leptospirosis and hantavirus.
Hitting a mosquito that bit you is also considered impulsive killing, rather than premeditated killing, and according to Bhikkhu Bodhi's description above, impulsive killing is less grave than premeditated killing.
Despite this, it is clear that not killing any sentient being for any reason, would be the higher dhammic decision.
Answer: Killing a mosquito should not be the first and initiative step. If you are honest and really struggle to maintain first precept better to make preventive measures. Just adhere to precepts will not create effective results. you have to adhere to precepts with wisdom in your capacity.
As preventive measures
1.you can use mosquito repellent.
2.Use mosquito nets
3.Close windows and doors early in evening before enter mosquitoes to your house
4.close small spaces and ventilation holes with fine nets in your houses
5.remove mosquito breeding places.(keep clean your surrounding)
above will protect your family effectively diseases spread by mosquitoes.Simply kill mosquitoes one by one is not effective and useless way.Above protective measures are more effective than killing them.In other hand you can protect first precept. "The protector of Dhamma will protect by Dhamma. May all being in peace and harmony. Thanks.
Answer: The precepts are training rules for training your mind. The first rule is to learn to control your hatred, and impulsive behavior based on that, like killing or violence.
Sometimes killing is necessary, for example killing of pests to get things to balance, or killing for food. But that is killing in clarity, not in hatred - done with wisdom and understanding. We are all connected here you know, and our lives will feed into others' in many different ways.
When I eat meat, I appreciate life of a sentient being who gave me their flesh for nutrition and promise to make good use of it. When I kill a mosquito I do it in full awareness, as a conscious choice, not an act of hatred. There's no regret in my killing of a mosquito and no guilt. For a moment I pause and think to make sure there is no other way to solve the problem, and if there's none - then with an attitude of "thank you, forgive me, I love you, but I have to do this" I kill it.
Comment: I'm not agree with your sentence  **"thank you, forgive me, I love you, but I have to do this" I kill it.**  With human you wouldn't say this, we forgive them and for animals we should love them and not kill. Now when I don't kill them as I gave up killing mosquitoes early, I regret if kill them mistakenly. But your answer worth so thank you so much.


Weak and strong squares

Question: I somewhat understand the concept of attacking the king and pieces, but "attacking" squares is a bit of a vague concept for me.
What are weak and strong squares? When do you use them? How do you create them?
Answer:
Weak squares are squares which cannot be defended by a pawn. [1][2]
... that all of the squares behind the pawns are weak by default.
Counter-intuitively: Strong squares are squares which are defended by a pawns.

These square are very powerful places for opponents Knights or Bishops. No pawn can attack to these pieces. In below position, square d6 is a weak square for black and also strong square for its opponent.
1r1q2k1/1pbr2pp/2pNp3/p1P1Pp2/PP1P4/3R1QP1/6KP/1R6 w - - 0 1

or square f5, h4 and e6 are some weak squares for black and also f3 and d4 for white (however it's too late for black to put his Knight there)
1n3q2/p6p/1p1p1pk1/3PpN1p/4P3/1PQ3P1/P4P2/6K1 w - - 0 1

They're useful to place a Knight or Bishop in near the heart of opponents position. Usually making a weak square in the opponents land needs long term strategy. You have to force the opponent to pass its pawns...
Answer: A square becomes weak when a pawn cannot protect it. For example, after white plays e2-e4 followed by c2-c4, the square on d4 becomes weak for white. Yet, the square on d4 becomes weak only when black has at least one piece that can use this weakness. In this example, the square on d4 is best used by a knight or bishop. To create a weakness, you should force your opponent to move a pawn forward. Make sure you have at least one piece that can take advantage of the created weak squares.
Answer: A weak square is a square that can no longer be protected by one of your pawns, or more generally, a square that can no longer easily be protected by one of your pieces.

In this example, the highlighted d5 square is weak for Black because they will never be able to control it with one of their pawns (this is actually a familiar sicilian pawn structure)
The concepts of weak squares are useful even to World Champions. In the following position, Botvinnik managed to exploit his opponent's weak squares in a few moves only:

I describe how in this explanatory video about weak squares: https://youtu.be/AZG4PU_ejK0

Weak and strong squares


Tool to backup my old Windows XP laptop hard disk before updating Windows

Question: When I use the Help and Support resource on my Toshiba laptop to run the backup utility for the entire hard disk, with about 30 GB of files, it copies only about 4 GB to my Memorex USB flash drive, then says that the media[sic] is full and asks for another media to be supplied.  Direct checking shows about 57 GB free and available.
I suppose that it could be either the backup utility or the flash drive that is causing this problem.
I don't see any option for the utility to change any limit on the size of the system being backed up, and I haven't found any quick and easy way to ask the Memorex manufacturer for advice at their website "PNY.com".
I looked for an alternative freeware backup utility and did not find one of reasonable size, I could download in one or two hours using my slooow AOL dial-up internet service.
Thanks to PHUCLV for the response to my initial request for help.
The comment about the FAT32 file system was very helpful in explaining why I couldn't backup the whole hard disk, but trying to make the necessary change to the flash drive file system was frustrating, since it seems to be the case
that the file system on this Memorex flash drive is fixed and unchangeable,
at least so far as I could determine from the Properties tab and the PNY.COM
website.
With the advantages of the NTFS system so great, I find it hard to believe that the product would be designed to be limited to the inferior FAT32 system.  Since I could not get any help from the PNY.COM website, I can only
hope that someone can suggest a way to change the file system given that the
Policies tab in the flash drive's Properties window does not give a choice.
After doing the obvious search, I learned how to reformat my flash drive so I no longer have a four GB file size limit to stop the backup.  Unfortunately, this just yields another problem: backing up over 30 GB on my hard disk seems to take forever.  I have tried two backup programs, and had to interrupt them both to use the computer for more urgent tasks. In each case, the estimated time remaining was three or four DAYS.  I understand that 30 GB is a lot of data, but the read of the hard disk and write to the flash drive ought to be much quicker.  The first time, I tried to backup using the data compression option.  After seeing how slowly the backup was going, I restarted using the raw data option.  If it was in fact faster, it still gave the estimated time remaining as several days when only about 25 % of the data had been copied.
Am I missing some option that could reduce the backup time to something more convenient, like overnight, perhaps?
Comment: If the USB flash drive is formated in FAT32 then it can't store files larger than 4GB
Answer: Clonezilla is a FOSS "partition and disk imaging/cloning program similar to True Image® or Norton Ghost®. It helps you to do system deployment, bare metal backup and recovery".


A Markov chain demonstration that doesn't require computers

Question: I have a large probability class and would like to do some memorable demonstrations of Markov chains for them.  Does anyone have any recommendations for a "low-tech" demo that doesn't involve computers (or at least, one that minimizes this requirement)?  I have access to all kinds of physical props like dice, poker chips, coin tosses, and so forth.
Answer: Per Wiki:
https://en.wikipedia.org/wiki/Markov_chain#Gambling

Suppose that you start with \$10, and you wager \$1 on an unending, fair, coin toss indefinitely, or until you lose all of your money. If $X_n$ represents the number of dollars you have after $n$ tosses, with $X_0 = 10$, then the sequence $\{X_n: n\in \mathbb{N}\}$ is a Markov process. If I know that you have \$12 now, then it would be expected that with even odds, you will either have \$11 or \$13 after the next toss. This guess is not improved by the added knowledge that you started with \$10, then went up to \$11, down to \$10, up to \$11, and then to \$12.

I recommend to make the following modifications though:

Use a smaller starting amount (3 or 5 or the like) so you can run a few examples.  Think it will take a while to exhaust \$10 bankroll.
Flip the coin, cover it, and then call on a student in class to guess it. Pick different students at random.  Pick a student (with good handwriting) or use a TA, to graph or tally the experiment as it goes, on the chalkboard.  (Makes it more interactive...human factor.)
Answer: The simpliest example I know is the ball game with at least three people: it starts with one person, having the ball, and every second (s)he throws it to another person randomly. Question: what's the probability that the ball gets to person X after n seconds?
Comment: If you do this with humans, it will be highly non-markow. Humans are bad at randomness and will tend to distribute the ball more evenly than random.


Trello Cards RSS Support

Question: We are using Trello and found it rather useful. Is there any way to have an RSS reader connect to our Trello account and show us all our cards?
Answer: No there is no way to currently do this. It is in the archives as a feature request.
Answer: I'm not sure if/when Trello will ever implement RSS feeds, so I went ahead and made a small web app that will generate them for you. It should work with either public or private boards (if you give it an auth token).
The source is on GitHub if you want to fork it and make your own changes, and here's a Trello board for it as well.

Trello Cards RSS Support


Addressing other members of the same great family when everyone shares the same surname

Question: Hypothetical situation, let's say we have a great familly meeting, where everyone have the same surname but some members of the familly see each other for the first time. Of course, introductions are made, so everyone knows each other names. Here goes my question: How would one person address the other when they barely know each other? I mean, they can use the surname, but that would be confusing, since everyone has the same. Will they make an exception and use their names instead, even though they see other members of the familly for the first time?
Comment: I'd guess they would use last name plus first name, i.e. "こちらは村上健志", but I'd like to here what someone else has to say.
Comment: Great question. In a business situation I ask for a 田中さん but I am told that there is more than one 田中. In this situation should I say "田中サチエさん" .
Answer: Of course they use their individual names (+ san).
Answer: I'd agree with the firstname-san in direct-greeting and 3rd-party mentions  , although once conversation is going i'd reckon any usual kochira-sochira patterns and (not-even-necessarily) relational titles (ojisan/obasan, uncle/auntie etc, possibly dropping the o and even perhaps the san later if the folk are friendly and the meeting/circumstances casual) for older folk are going to seep in.. But definitely firstname-san(/-sama for a higher formality; clan heads/relations//functions etc?) would work generally, i believe.
((I've seen colleagues with the same surname move easily enough into firstname-san patterns, and while these folk in the question might not really know each other they .are. still family at the end of the day..? ..is what i'm thinking. n_n"; ))
Answer: How do you address your own father? Do you use his last name or first name?
Most people use neither. Most people will say "Dad".
That is the same with all other family members.
Most people will address one another using "uncle", "aunt", "cousin", etc.
Usually the first name is used only to address children.
Comment: `using "uncle", "aunt", "cousin"` -> uncle ->「おじさん」, aunt ->「おばさん」... cousin -> ???


How to add banana flavor to my cookies?

Question: I want to add the smell and flavor of banana in my cookies. I'm not sure whether I should substitute APP-flour or butter with banana. Thank you.
Comment: Have you considered powdered freeze-dried banana (or grinding up freeze-dried banana yourself) or some sort of banana extract?
Comment: powdered freeze-dried banana?? i never though of that but i don't think it will help with flavor, for the smell might be good idea though.
Comment: Flavor is smell. Mostly.
Answer: Banana adds structure & moisture to baked goods, so you'd actually have to replace some egg, some butter, and some flour. When doing complex substitutions like this, it's usually best to find a recipe that's actually for the kind of cookie you want, in this case banana. Otherwise, you could just add some banana to the recipe as it is and go from there.
Of course, an easier method would be to use banana extract, which would replace the vanilla or other flavoring in your cookie.
Answer: You can generally replace oil in muffins and cookies with mashed fruit (applesauce, bananas, etc.)  I've had good luck with replacing up to 2/3 of the oil with an equal volume of mashed fruit in muffins without problems.
Butter however is a bit trickier, as it depends on how it's being used in the recipe.  If it's melted, it shouldn't be a problem to substitute.  If it's creamed, it's going to create a completely different texture.
I'd agree wth sourd'oh : there are plenty of banana cookies out there ... I'd start from one of those, and if you don't like how they come out (eg. too cakey or too chewy), then adjust the recipe for your tastes.

How to add banana flavor to my cookies?


How do you set GPG to use ElGamal and RSA for keys?

Question: How do you set GPG to use ElGamal and RSA for my GPG key? I'd like to do it but for the life of me I can't figure out what options to use.
Answer: --gen-key
Generate a new key pair. This command is normally only used interactive.
--cipher-algo name
Use name as cipher algorithm. Running the program with the command --version yields a list of supported algorithms. If this is not used the cipher algorithm is selected from the preferences stored with the key.
Google is your friend....
http://www.gnupg.org/documentation/manpage.en.html
Answer: Generate a new key RSA master key that is only capable of certifying or signing and certifying.  Then edit the key to add an RSA signing subkey.  Then add an encryption subkey and select El-Gamal instead of RSA.  It takes a few minutes longer (maybe more than a few, depending on the size of the keys), but it's worth it.
One of these days I'll get around to digging out my step-by-step instructions for the process and putting them somewhere useful.  Customisations like this are only really possible through the command line, but it's not that much of a chore.


Existing solutions to test a NSIS script

Question: Does anyone know of an existing solution to help write tests for a NSIS script?
The motivation is the benefit of knowing whether modifying an existing installation script breaks it or has undesired side effects.
Answer: Unfortunately, I think the answer to your question depends at least partially on what you need to verify.
If all you are worried about is that the installation copies the right file(s) to the right places, sets the correct registry information etc., then almost any unit testing tool would probably meet your needs. I'd probably use something like RSpec2, or Cucumber, but that's because I am somewhat familiar with Ruby and like the fact that it would be an xcopy deployment if the scripts needed to be run on another machine. I also like the idea of using a BDD-based solution because the use of a domain-specific language that is very close to readable text would mean that others could more easily understand, and if necessary modify, the test specification when necessary.
If, however you are concerned about the user experience (what progress messages are shown, etc.) then I'm not sure that the tests you would need could be as easily expressed... or at least not without a certain level of pain.
Good Luck! Don't forget to let other people here know when/if you find a solution you like.
Answer: Check out Pavonis.
With Pavonis you can compile your NSIS script and get the output of any errors and warnings.
Answer: Another solution would be AutoIT.
You can compile your install using Jenkins and the NSIS command line compiler, set up an AutoIT test script and have Jenkins run the test.


What are the main source texts for the chavruta and teacher-student models in Jewish learning?

Question: I'm working on an outline for a short presentation on how new online tools, especially this site, interact with the traditional Jewish learning models of chavruta and teacher-student. What are the main source texts (I suppose mostly in the Talmud, though some may be earlier and later) for the roles and benefits of these two models and the interplay between them? If there's a particular commentary or contemporary source that sums up traditional understandings of any of these primary sources, that would be great to have, too.
Answer: A few raw blobs off the top of my head.

The Gemara has "Cherev al haBadim" -- a curse on those who study all alone. Moreover, they become foolish and make mistakes. I (Shalom) heard one rosh yeshiva say that means you always need a chavrusa ("and I even asked my chavrusa to come to my house during sheva brachos week so we could learn"); and another who said that means you can study alone, but every so often compare with others ("some people even send a chavrusa to the house for sheva brachos! What kind of nonsense?").
Choni Ham'agel's "oh chevrusa o misusa."
Shaul Stampfer's work on the 19th-century yeshiva says it appears in Volozhin (at least at one point), a chavrusa would be for a weaker student if he needed help; most studied alone.
Gemara in Sanhedrin that in Babylonia "mechablim zeh et zeh bahalacha", ("we beat each other up arguing over halacha"), whereas in Israel "man'imim zeh et zeh" ("we support each other pleasantly." I once witnessed this with two Israelis, one going, "I'll take what you're saying one step further", and the other "I'll take what you're saying one step further", even if that wasn't what was intended!)
Comment: Are you sure that second one has anything to do with learning. . . or partnerhood? (או חברותא או מיתותא)
Comment: @WAF, the context seems to be (IIRC) that Choni walks into the study hall and no one will talk with him. Learn whatever lesson you like from there.
Answer: I don't know if this is what you are looking for, but the famous story surrounding the death of Reish Lakish (bottom of Bava Metzia 84a) plays out the benefit of a proper chavrusaship.  A translation is here.
R. Yochanan was upset following Reish Lakish's death, and the rabbanan sent R. Elazar b. Pedas to learn in Reish Lakish's stead.  R. Yochanan felt the chavrusaship was unproductive, since R. Elazar merely supported (textually) everything R. Yochanan said.  With Reish Lakish, R. Yochanan had to defend his position and this allowed a broader understanding of the halacha.
Answer: Mishna 5 Perek 5 in Sanhedrin mentions a partnership in learning between dayanim in the case of a death sentence that is unfavourable. In such a case the final judgement is delayed until the following day. Part of the mishna mentioned above reads:

אם מצאו לו זכות, פטרוהו.  ואם לאו--מעבירין דינו למחר, ומזדווגין זוגות זוגות, וממעטין במאכל, ולא היו שותין יין כל היום, ונושאין ונותנין בדבר כל הלילה, ולמחרת משכימין ובאין לבית דין.

This loosely translates as: "if they find him meritorious he is exempt [from punishment]. If not, his sentence is delayed until tomorrow. [The dayanim then] pair off ['...in order to deepen their understanding' (Kehati)], they diminish in their food intake, don't drink wine all day and critically analyse the case all night ['each and every dayan in his own pair, or alone' (Kehati)]. The next day they arise to the Beth Din".
Although its not possible to learn out a general rule for chavruta study from this mishna, it can certainly be seen as meritorious and something that was done for in-depth understanding.
Answer: A source for the role and value of havruta-style learning is Taanit 7a which states

אמר רבי חמא (אמר רבי) חנינא מאי דכתיב (משלי כז, יז) ברזל בברזל יחד לומר לך מה ברזל זה אחד מחדד את חבירו אף שני תלמידי חכמים מחדדין זה את זה בהלכה
Rabbi Ḥama, son of Rabbi Ḥanina, said: What is the meaning of that which is written: "Iron sharpens iron, so a man sharpens the countenance of his friend" (Proverbs 27:17)? This verse comes to tell you that just as with these iron implements, one sharpens the other when they are rubbed against each other, so too, when Torah scholars study together, they sharpen one another in halakha.

an additional resource on the efficacy of this mode of study is the work A Philosophy of Havruta: Understanding and Teaching the Art of Text Study in Pairs
Regarding the teacher-student learning model, it was not clear to me from the question if this refers to pedagogy or the student serving/attending to the teacher. For the latter please see שימוש חכמים and in particular Berachot 7b

וא"ר יוחנן משום רבי שמעון בן יוחי גדולה שמושה של תורה יותר מלמודה
And Rabbi Yoḥanan said in the name of Rabbi Shimon ben Yoḥai: Service of Torah is greater than its study,

i.e., serving a Torah scholar and spending time in his company is greater than learning Torah from him.(translation and commentary from Sefaria)
See also ibid 47b and Avodah Zara 19a
Though there are examples in the talmud of the teacher asking questions to 'sharpen' the students; my own analysis is that the teacher was seen as the source for information whereas the study partner was used to analyze the plumb the depths of that information.


Regarding the adjective "Христов"

Question: The adjective Христов looks quite unique to a learner such as myself. I can't think of any others that look like it; meaning it lacks the characteristic -ый/ий/ой endings (and their inflected forms) I'm used to. It also seems to follow the declension pattern of a noun (or more specifically, male surnames, where the instrumental and all the plural forms are inflected like adjectives). I'd like to know why this is. Is it a grammatical holdover from Old Church Slavonic or Old East Slavic? If so, how did it come about, morphologically speaking? I'm only familiar with -ов in modern Russian, where it is an ending for plural nouns or singular male surnames. How was Христов formed from whatever the noun form of "Christ" was at the time?
Comment: Will you provide some context,  a sentence at least? I believe it's possessive from Christ.
Comment: Sure. From the Wikipedia article on Иисус Христос:
"Необходимость вкушения тела и крови Христовых в таинстве причащение (Ин. 6:48—58)"; "В православной иконографии на иконе Воскресения Христова изображается момент схождения Спасителя в ад и изведения из ада душ ветхозаветных праведников. " We can see it follows the noun(s) it describes and matches said noun in number and gender. I found it curious because it doesn't look like a typical adjective. I was also surprised not to see "Христоса," the genitive of Христос, used instead.
Comment: As a side note, you are right about surnames (though, as others said, it is the names that are derived from the possessive form). Христов is a known surname; for exampe, [Борис Христов](https://en.wikipedia.org/wiki/Boris_Christoff) was one of the world's greatest basses (he was a Bulgarian though).
Answer:
I can't think of any others that look like it

Tons. Отцов, дедов, братов etc.etc.

I'm only familiar with -ов in modern Russian, where it is an ending for plural nouns or singular male surnames

Actually it's surnames which are produced from possessive forms, i.e. Петров means Peter's [son].

I was also surprised not to see "Христоса," the genitive of Христос, used instead

Genitive of Христос is Христа.

Is the -ов we see in possessive adjectives the same -ов we see in the inflectional ending for masculine nouns in the genitive plural today? Or is it etymologically unrelated?

These are different and do not always coincide. For example, братов (possessive) vs. братьев (gen. pl.).

I would have thought Петра would be "Peter's," whereas Петров would be "Peters'"

Петров = "Peter's" or "of Peters"; Петра = "of Peter".

Is it still a productive ending today

Yes, but it applies only to animate nouns, just like "'s" in English. Also Genitive is definitely more popular nowadays, which is especially true for "modern" words. So making possessive of such words is somewhere between "not recommended" and "wrong".
Comment: Thanks! I'll edit that mistake out. Is the -ов we see in possessive adjectives the same -ов we see in the inflectional ending for masculine nouns in the genitive plural today? Or is it etymologically unrelated? If it is related, has it shifted its meaning or was it used for plural nouns then as it is now? Because I would have thought Петра would be "Peter's," whereas Петров would be "Peters'". Is it still a productive ending today with regards to building possessive adjectives, or are there a set number of very old ones that use it and newly coined poss. adjectives follow a different pattern?
Comment: @GinésdePasamonte Answer's updated.
Answer: In Russian we have got possessive adjectives, which mean belonging to a person or an animal (singular ):

мамина сумка, отцовы кроссовки, кошачьи следы, нянькины сказки, кровь Христова братовы  ботинки.

They are equal to a noun+noun structure

сумка мамы, кроссовки отца, следы кошки, etc.,

but this structure can show belonging to ownership in plural: ботинки братьев.That's why, they say,there's a tendency to use a noun+ noun structure or adjectives ending with -овский,ский more often.
The suffix -ов,(-ев) helps to form adjectives from nouns (masculine, ending with hard(soft) consonant

Отец – отцов, брат– братов, Христос – (we remove -ос) Христов, Христова, Христово.

We also remove -ос in declension :

Христос, Христа,Христу, Христа, Христом, о Христе. (храм Христа Спасителя).

Matt has already mentioned surnames,  which were formed with the same suffixes.
Comment: To me, "кошачий" is not a possessive adjective. It means "characteristic of cats" rather than "a/the cat's". "Следы кошки" is equivalent to "кошкины следы".
Comment: Принадлежащие кошке, кошачий хвост- что тогда? Характерный или принадлежащий?
Answer: To illustrate this short-form adjectival construction with last names in another setting, I have seen it used sometimes in math to name concepts after people: Артин --> артинов модуль (Artinian  module), Риман --> риманова поверхность (Riemann surface), Банах --> банахово пространство (Banach space), and so on. It also occurs in physics: Ньютон --> ньютонова механика (Newtonian mechanics). If the name ends softly then -ов becomes -ев: Абель (Abel) --> абелев интеграл (abelian integral), абелева группа (abelian group), and абелевое многообразие (abelian variety). As other answers have indicated, this method of forming an adjective out of a name seems old-fashioned. Far more often I see the genitive following the noun, e.g., сфера Римана (Riemann sphere), not риманова сфера.
It is standard to use a lower-case first letter (артинов rather than Артинов, unless it is the first word of a sentence), and this short-form adjective precedes the noun. Neither of these is the case with your example of Христов; native speakers are welcome to comment on that.
Comment: Capitalization depends on whether it is descriptive or possessive adjective. If it ends in "-ian" in English (Cartesian product, Newtonian liquid, Riemannian manifold), it's descriptive and is not capitalized in Russian (*декартово произведение*). If it ends in "'s" in English or is used unchanged (Newton's laws, Riemann sphere), it is possessive and is capitalized in Russian (regardless of being used in genitive or as a form in *-ов, -ев, -ин*)
Comment: @Quassnoi I agree possessive is capitalized genitive, but I have never seen short-form adjectival names (-ов/ев) capitalized if not the first word. For example, in the slides at http://matematika.phys.msu.ru/files/a_stud_spec/256/lectioni-7.pdf it is банахово пространство throughout, not Банахово, and this is an example where the term in English, Banach space, leaves the name unchanged. Also, Riemann surface uses the name unchanged but I have only seen риманова поверхность, not Риманова поверхность.
Comment: For example, see the notes on Riemann surfaces at http://www.mi.ras.ru/noc/lectures/01chirka.pdf, even just the introduction.
Comment: + булева алгебра (Boolean algebra)

Regarding the adjective "Христов"


Hard wiring condensate pump with ground to furnace with only hot / neutral

Question: My 1996 oil burning air handler has a hard wired condensate pump for AC that recently died. Newer condensate pumps all seem to plug into the wall via a three prong plug. I do not have an outlet near the furnace (the house is all armored cable), so planed to strip the power cord from the new condensate pump and hard wire it to the furnace as was done with the existing pump. HOWEVER, when I opened up the junction box inside the furnace, there is only a hot and neutral connection (again goes to armored cable to the furnace motor).  Can I connect hot to hot and connect neutral + ground to neutral to complete the circuit? Is there any other process to attach the ground wire from the new pump? It's hard to see but the green wire running to the motor is attached to a screw in the back of the box. Can I attach the ground under the screw too? Thanks!!
Comment: Welcome to StackExchange!   You've got most of the terms right, but "positive" is actually called "hot".   It's *Alternating Current*, they are both positive and negative alternating.  It would seem like they're  both hot, except that one of them (neutral) is intentionally bonded to earth/ground for safety, so it is unlikely to bite you.   The ungrounded one is "hot" and will bite.
Comment: With they may be using the armor clad for the equipment ground.
Comment: Can you post photos of the inside of the box please?
Comment: @EdBeal  Definitely agree that the actual air handler is grounded through the armor, but how do I connect to it with a ground wire?  I will try to get a better photo showing the existing connections. There is a screw in the junction box that I might be able to ground to, but there is already a connection there and I can't figure out what it is going to in the pump (maybe it doesn't matter?)
Comment: Is there a terminal block/box on the condensate pump that the cord attaches to, or is the cord permanently fitted to the condensate pump?
Comment: @ThreePhaseEel The cord is permanently attached to the pump.
Answer: Use a pigtail for the ground and a cord grip for the cord
With the power off:

Fit the cord grip (a Cooper/Crouse-Hinds NCG50-50 will do the trick) to a knockout in the box using a matching locknut and run the cut-off cord end through it, then tighten the cord grip down. This provides strain relief and sealing for the cord connection, which is permitted here by NEC 400.7(A) point 7 (preventing the transmission of vibration; in this case, from the pump to the rest of the furnace).
Wire the cord hot to the furnace hot, and the cord neutral to the furnace neutral
Remove the existing wire from the ground screw, and nut it together with a length of bare 12AWG as well as the ground from the cord
Land the length of bare 12AWG (this is a pigtail for the ground) on the existing ground screw in the box
Button it all up and turn the power back on
Comment: @Sarah -- we thank people around here by upvoting and accepting their answers :)
Comment: Got it!  Pump is up and running and was a quick fix thanks to your help!


What are the options available to convert Bitcoin to Paypal USD?

Question: I have, recently, started earning some Bitcoins from CoinURL.com. I want to know all the options available for converting these earned Bitcoins to Paypal USD.
Comment: @StephenGornick: I understand you in full spirit but bitcoin system doesn't have many (rather any) options in my country. I guess, a fair option for me will be to exchange them with someone who can use them with the bitcoin merchants.
Comment: If you are obtaining this income from the bitcoin community, wouldn't it be good business to then patronize  a Bitcoin merchant for at least some of this income?  There are so many things you probably are already paying for where there is a way to make the same purchase in bitcoins.  Some options are even cheaper in bitcoins, such as prepaid wireless in the U.S., for instance. - http://en.bitcoin.it/wiki/Trade
Answer: The factors that matter for any cash-out decision are:

Where are you located (country)?
How much are you looking to trade?
What type of cash are you looking to receive?
How soon do you need access to the proceeds?
Is privacy important?

Specifically for cash-out to PayPal, options include:

http://snapswap.us/#/paypal (You'ld need to do BTC -> XRP first though. http://Shapeshift.io lets you do that.)
http://www.VirWoX.com  (BTC --> SLL, SLL --> USD)

Other ones that are not as widely known -- proceed at your own risk:

http://www.btctopp.com
http://www.exchangemycoins.com/pages/sell-bitcoin-paypal
http://order.payexchanger.com/index.php?a=add (You Give="Bitcoin", You Want="PayPal")
http://24pay.me

What might exist is a service that lets you pay for charges with Bitcoin and then the recipient gets to withdraw the proceeds of the sale using PayPal. So you would simply need to sell to yourself.
For example, I see that Fiverr accepts BItcoin for payment: http://blog.fiverr.com/fiverr-now-accepting-bitcoins and I believe they offer withdrawal via PayPal http://www.youtube.com/watch?v=px_eYHCgGZ4. So you simply would create two accounts, list a task, and transact with yourself. Obviously the account for buying (and paying with Bitcoin) would need to be something that you wouldn't want associated with your real identity. Additionally, you probably want to do the listing with one IP address and the buying on another just in case they check for that kind of stuff.
Maybe when PayPal is a cash-out method for Amazon (coming, apparently http://recode.net/2015/04/09/paypals-big-change-it-can-work-with-amazon-after-ebay-split/ ) then maybe you can sell to yourself (buy Amazon gift cards to pay, then cash out to PayPal from the proceeds of the sale to yourself.)
BitLanders is another service that lets you trade with yourself, paying with Bitcoin and withdrawing in PayPal. Also, apparently if your sales aren't enough to cover your withdrawal amount you can make up the difference with Bitcoin.
Comment: If you accumulate enough to meet the Fastcash4Bitcoins.com minimum, then that's probably your best bet then.
Comment: I'm pretty newbie to bitcoin and most of those factors go over my head for now. My bitcoin source is consistent and I will be getting them on regular basis. I'm looking for PayPal USD as it is the only service that allow withdrawals (low fees) to my country. Private exchanges are obviously preferable.
Answer: bitinstant now does btc-> paypal.
also you could try selling coins for paypal to individuals on bitcoin-otc (though you have to watch out for chargebacks).
Comment: yes, the **chargebacks** are really an issue to look after. I have been deceived few times trying to sell Amazon.com Gift Certificate Codes (so I moved to [this](http://gum.co/mLeZ) service).

And one more thing, I'm checking out [Bitinstant](https://www.bitinstant.com/) right now. I can not find btc to paypal option there, only coupons to paypal.
Answer: You have for example https://www.spendbitcoins.com/, http://www.fastcash4bitcoins.com/ and https://www.bitinstant.com/.
PayPal is notorious for freezing accounts of people who use it for Bitcoin conversions, so it is not clear how sustainable these services are.
Comment: I came to know about these sites after yesterday's extensive internet searching about BitCoins. Question is are they genuine and can be trusted ?

**Is there any work-around about this PayPal problem ?**
Comment: @AbhishekM.: Yes, these services can be trusted.
Comment: @AbhishekM.: The only BTC->PayPal service I've used is CoinCard (http://coincard.ndrix.com/), which was excellent but unfortunately is no longer doing PayPal. But the sites I mentioned have existed for a long time and/or are run by well-known and respected members of the Bitcoin community. Note also that the level of trust required for an immediate exchanger is much lower than for an exchange that keeps deposits.
Comment: I would appreciate if you mention the sites that worked for you.
Answer: There is an IRC channel #bitcoin-otc in which people trade bitcoins with each other.  There are often people there wanting to buy Bitcoins for PayPal.  http://bitcoin-otc.com/ will tell you about the channel, and how to register with the channel's bot to build trust with the users there.
Be way accepting PayPal for bitcoin, since PayPal is reversible and Bitcoin isn't.  Check the rating of the person buying your bitcoins and be very careful before dealing with people who have low ratings.
Answer: This site https://www.bitcoinary.com/ is providing exchanges with paypal also.
But it is  build on different scheme. You are relying on people rather than market.
One thing to be aware of is secure connection which does not work for me, although it can differ with others.
Answer: On Jul 14 2012 at 10:13 Abhishek M. wrote "I want to know all the options available for converting these earned Bitcoins to Paypal USD."
There are nine different bitcoin debit cards available on the first 10 results when you Google 'bitcoin debit cards':
https://www.google.com/search?q=bitcoin+debit+cards
ANXBTC.com says "let your Bitcoins do everything your credit cards can do" and "Spend your bitcoins on a global network that has over 25 million merchants just like any credit card!". https://anxbtc.com/pages/card
Xapo.com says "swipe it at your favorite brick and mortar merchants or enter the card information at any online destination". https://xapo.com/wallet/ This is not necessarily all rosy, because when you read the fine print you may see shocking bitcoin debit card fees. However, not all bitcoin debit cards are the same, and players do change their offers and have special deals.
A more comprehensive look would involve the analysis of the withdrawl fee structure for bitcoin debit cards, and all associated expenses, and then compare that to total Paypal fees. Perhaps a debit card could work for you, and you won't have to risk your capital with Paypal in the United States.
Finally, crypto technology firms like ShapeShift.io and HolyTransaction.com offer the ability to shape your bitcoin into many other cryptocurrencies. These types of services can be blended with other perhaps local companies, and could give you more options for exchanging the value of your earned bitcoins affordably, easily, and with possibly lower withdrawl costs than Paypal.
Many consumers find bitcoin backed debit cards are a convenient and affordable alternative to traditional payment systems.
Answer: Understand that your solutions are most likely to be expensive and corporate*. PayPal is not a fan of Bitcoin and you won't find many individuals willing to to accept PayPal for Bitcoin, and you should, too, be wary of accepting PayPal as an individual.
See also: Why shouldn't I accept PayPal when trading bitcoin?
*corporate means not an individual, but a company with established rapport and customer base, with sufficient means and experience to navigate or mitigate the high potential for chargebacks when selling BTC via PayPal.
Answer: You should try using localbitcoins. they have an option to sell bitcoin for paypal and vise versa and the sellers are legit. There are limits and there is a commision % but the sellers have high reputation and are reliable. For a detailed tutorial how you can visit this blog: http://www.btcfeed.net/tutorials/convert-paypal-to-bitcoin/


Should I disclose information about my house for deemed acquisition/disposition purposes in Canada?

Question: I am in the process of migrating to Canada and I was asked to disclose my assets in my home country by my tax advisors. I do have a house there which was registered to my name from my mother's. Should I disclose this asset? What are the consequences of not disclosing it and how likely is it that Canada would find this information if I don't disclose?
Comment: It's hard to see how your tax advisors can advise you correctly if they don't have a full understanding of your personal circumstances. What is your concern about disclosing?
Answer: Is this disclosure needed for immigration procedure (you have not yet lived in Canada) or you have already lived in Canada and the disclosure is related to Canadian tax? If the former, you probably want to be more specific on which category you apply and where you are in the process.
If the latter, this question probably better asked in Personal Finance & Money Stack Exchange as it has nothing to do with your immigration status: anybody with residential ties to Canada (i.e. Canadian Tax Subject) will have to disclose foreign assets which reach the value of $100,000 or more at any time in that year, regardless of immigration status. If not, and you get caught in the future, you may have to pay the greater of $24,000 or 5% of the asset value, for each year you fail to disclose. Note that income from assets will also need to be reported, even if the assets' value is less than $100,000.
As how Canadian government — or more specifically CRA — can find out, there are many ways. For one, there are now information sharing agreements with most countries. Then, even if you somehow avoid detection while owning the land as is, one day you may want to transfer its ownership or do something else with the land, which is more likely to be noticed, in which case CRA will start investigation. Note that CRA can do a lot to you from suspicion alone, especially since it is not a criminal investigation.
Please also read these articles:

How the CRA will uncover your offshore assets and what you should do about it
Questions and answers about Form T1135
Don't forget foreign assets when you file your tax return
Common Reporting Standard Is Now Fully In Effect – If You Have Been Hiding Funds Or Assets Offshore, Now Is The Time To Disclose


Validate Primary Key and Index Selection

Question: I have a table that will store transaction data from store sales registers, I have read quite a bit on index and key choice and below is what I have concluded is the best option but I am new to this level of table design so advice would be greatly appreciated.
The table will be queried mainly on looking for a specific transaction (TrxDate, StoreNo, RegNo and TrxNo) or summarising data by TrxDate/ StoreNo.
Do my indecies look correct? Should the UX_POS_eCommTrx_TrxDate_StoreNo_RegNo_TrxNo_SeqNo index be a primary key? Is it worth adding another index just to cover looking for specific transactions (same a UX but without SeqNo)?
This is going to be a key table as the database grows and I really want to avoid having to change things round once the table has grown significantly.
<code>CREATE TABLE sfs.tbl_POS_eCommTrx
(TrxDate int NOT NULL,
    StoreNo smallint NOT NULL,
    RegNo smallint NOT NULL,
    TrxNo smallint NOT NULL,
    SeqNo tinyint NOT NULL,
    SKN int NOT NULL,
    Pcs smallint NOT NULL,
    Retail decimal(38,4) NOT NULL,
    CorrTend numeric(1,0) NOT NULL,
    OrderID int,
    UID int NOT NULL identity(1,1),
    DateStamp datetime Default(getdate())
)

CREATE UNIQUE INDEX UX_POS_eCommTrx_TrxDate_StoreNo_RegNo_TrxNo_SeqNo
    ON sfs.tbl_POS_eCommTrx (TrxDate,StoreNo,RegNo,TrxNo,SeqNo)

CREATE INDEX IX_POS_eCommTrx_TrxDate_StoreNo
    ON sfs.tbl_POS_eCommTrx (TrxDate,StoreNo)
</code>
Thanks in advance.
Comment: Not sure why TrxDate is an int.
Comment: I had only set it as [int] as other tables created in the database by others use that data type for the date (format YYYYMMDD, though you probably realised that) and I wasn't sure if issues would arise if I changed it for this table, if you could advise?
Comment: Apologies, amended to tag as sql-server, 2005 to be exact
Answer: I wouldn't get too hung up on estimating the correct indexes ahead of time.  Make the ones you think you'll need then watch the missing index DMV's after you get some data in the table.
In my experience, it's pretty difficult to correctly estimate the indexes that will have the biggest impact until you start actually querying the data, unless you know EXACTLY the queries you will use.  If you DO know exactly the queries you will be using, post them so we can help you.
You will also want to view the estimated and actual execution plans for any queries you do make, looking for table scans with an eye to converting them into index seeks.


When can I send 80 byte OP_Returns?

Question: I heard bitcoin-core 0.11 allows 80 byte OP_Returns, but I know miners operate different implementations and was wondering when it would be likely that 80 byte OP_Returns will be swiftly included in blocks.
Answer:
As you can see, only 10.8% of nodes have upgraded to 0.11 and 29.3% of nodes use a pre-0.10 distribution. (Source: https://getaddr.bitnodes.io/dashboard/#user-agents)
Considering that we don't know the hashing power of these nodes and don't know your definition of "swiftly included", there's no way to exactly answer your query.
However, if you assume hashing power to be equally distributed between nodes, There's about a 10% chance that any give block will be mined by someone running 0.11, so about a 47% chance that a 0.11 block will be mined at least once an hour.
Comment: Keep in mind that this is a relay rule. It affects how the transactions make their way around the network as well.
Answer: I remember having the same question when the initial OP_RETURN ability came out in Bitcoin Core 0.9, but most of the network was still running 0.8.
I remember that it began to be reliable to send OP_RETURN transactions and get them mined once around 30% of the network was willing to relay them.
So you should keep an eye on https://getaddr.bitnodes.io/dashboard/#user-agents for a similar %age.

When can I send 80 byte OP_Returns?


Can facehuggers be tricked?

Question: The Can you hide your face from a facehugger? question made me think of a similar question: can facehuggers be tricked?  How do they recognize faces? (They clearly recognize faces for a variety of animals.) There are plenty of androids in the Alien universe; have there ever been any cases where a facehugger encountered an android?
Comment: Why do they need to recognize faces? They just need to recognize an orifice (or maybe not even that). I don't think they care much about the fact that humans tend to call them "facehuggers".
Comment: Not that I can see...the [**Wikia**](http://avp.wikia.com/wiki/Synthetic) has a great deal of information on this. Whether it's canonical is open to interpretation.
Comment: I seem to recall in Aliens (maybe the novelization) that Bishop agrees to crawl through the tunnel to the remote terminal based on the assumption that the aliens wouldn't target him (and he's the only one qualified to fly the dropship remotely). But he DOES get attacked in the tunnel, but perhaps the alien was only responding to the sound he made while crawling.
Answer: The attacked-to-face instinct is something that is part of the species reproduction system.
Observe a cat giving birth: it will know by default all necessary elements - the actual birth, the severing of the ombilical cord, the sanitization of the new-born, checking of life signs and later on the feeding process. A cat and all other species except now-days humans are self-sufficient when giving birth, because it's part of their species reproduction.
The process by which the facehugger attaches to a face is part of its genetic programming and he will be able to do it (he will know what to do by genetic memory). Some relevant conclusions can be seen from the first Alien movie, specifically how the facehugger deals with a human inside a space suit.
The facehugger still attacks the suited man, even if his face is not directly accessible. So the facehugger knows about its target, even if it is protected.
Although the basis of its detection capabilities are not well known, it is still able to correctly determine if the target is a valid host. So it acts by adapting to remove the obstacle by secreting acid until it reaches the host. So this answered part of your question: it cannot be tricked, not in an easy way.
Note that it is less relevant if the Alien species was genetically adapted to breed with mostly human hosts or not, because they proved to be extremely adaptable and able to genetically improve themselves in a single generation.
As for synths, since Aliens could distinguish living organisms from non-living ones (like synts), there is no chance a facehugger would attack a synth for reproduction / hosting purposes.
Answer: I seem to remember from one of the Dark Horse Alien comics that facehuggers attack based on body heat, which is why they don't detect androids as prey. I can't remember if it's stated how they locate the face, but perhaps it's something like terrestrial parasites being drawn to the heat and moisture of breath?

Can facehuggers be tricked?


Calculate grand total on order

Question: I know grand total is calculated on quote, I would like to find out is there a way to create an order object, add items to it and then get it's grand total without just manually adding item prices to get sum. Also this needs to be done without saving the order.
Comment: Perhaps a stupid question, but it sounds to me like you want to temporarily use a order object? Something a quote object actually already is. What is the quote functionality missing that you need to use temporarily order object for?
Comment: Good point. What I am trying to do is to make multiple order objects out of one order objects with different data. The reason I am not using quote object is that I need to add some existing order items to order objects, so I would need to convert these to quote items if using quote. Another reason is that I need increment id, and some other stuff that are order specific.
Answer: To calculate and process the grand total you need to follow these
<code>$quote = Mage::getSingleton('checkout/session')->getQuote();
    $address = Mage::getSingleton('checkout/session')->getQuote()->getShippingAddress();
    $address = Mage::getSingleton('checkout/session')->getQuote()->getBillingAddress();
    $quote = $address->getQuote();
    $session= Mage::getSingleton('checkout/session');
                $items = $session->getQuote()->getAllItems();
        //$items = $quote->getAddressItems($items);
    //echo '<pre>'; print_r($items);

    if(Excellence_Fee_Model_Fee::canApply($address)){
                 //$exist_amount = $quote->getFeeAmount();
                    // $fee = 1000;
                        //$fees = $fee * $result;
                    $balance = 1000;
                        //          $balance = $fee;

                        //$this->_setAmount($balance);
                        //$this->_setBaseAmount($balance);
                        $address->setGrandTotal($balance);

                        $address->setFeeAmount($balance);

                        $address->setBaseFeeAmount($balance);
                        $quote->setGrandTotal($balance);
                        $quote->setBaseGrandTotal($balance);
                        //echo '<pre>'; print_r($quote);
                        $quote->setFeeAmount($balance);
                        //echo '<pre>'; print_r($quote);

                        $address->setGrandTotal($address->getGrandTotal() + $address->getFeeAmount());
                        //echo '<pre>'; print_r($address);
                        $address->setBaseGrandTotal($address->getBaseGrandTotal() + $address->getBaseFeeAmount());
                        //$address->getGrandTotal();
                    //echo '<pre>'; print_r($address);
                    echo  Mage::getSingleton('checkout/cart')->getQuote()->getGrandTotal();
</code>
This is working on checkout and cart page to update the grandtotal.
Hope this will help you and you find a correct solution.
Answer:
without just manually adding item prices to get sum.

Magento does not provide a built-in function to calculate the totals as it does for quotes (collectTotals). The above would be approach that comes to mind. Of course it misses things like taxes, discounts, shipping, etc so if possible I would look into what Tim suggests using the quote object instead.

Calculate grand total on order


Can sign language be used for public Torah reading?

Question: We would like to perform a minyan for the deaf. All the participants can speak verbally, but cannot hear, including the Torah reader. Can he sign the words that he is reading during Kri'at Hatorah, or is there a halacha that the Torah must be specifically oralized and only in Hebrew?
Comment: You should *really* consult a knowledgeable rabbi for this issue.
Comment: Is the obligation\mitzvah to "read" or to "hear?"
Comment: ASL or Hebrew sign language? (Not sure if this makes a difference.) Also, looks like three separate questions. 1. Oral/speaking, 2. Hebrew only, 3. Does HSL count as Hebrew?
Comment: I don't think it matters, as deaf people aren't obligated in this mitzvah. That being said, I'm still curious as to the halachic status of sign language.
Comment: I don't understand the question. the reader is not saying it by heart so what can be wrong with assembling a group of Jewish people to read from the torah?
Answer: Rabbi Dovid Stein of Beit Kenesset Chatam in Rehovot has a large group of deaf people come and read Parshas Zachor from the torah every year. Meaning that each individual comes to the torah and reads for himself. Presumably this is because "krias hatorah" needs to be just that - reading from the torah, and sign language is not considered to fit into the halachik category of reading.
There are those who say based on the Rambam in Tefila 12:1 that the requirement to read the torah is a requirement of the community, but not of any one specific individual, and therefore if one were to miss some of the reading he does not have to make it up, because he is not individually required to hear it. (This would be in distinction from hearing meggilas Esther on Purim.) If that is the case, the same would hold true for deaf people. They are not individually required to hear the reading, and so it would not be necessary to have the reading signed to them.
Comment: Nice answer. Sorry I'm accepting it just now. Incidentally, according to many opinions, someone wearing cochlear implants may blow the shofar and he can also read megilla for others, despite the fact that he is deaf once he removes them.


Install software in the cloud

Question: Is there a way to have a windows xp running in the cloud and install software on it that more people in the organization can use? This in order to reduce the money spent on licenses for more developers
Comment: Re: reducing licenses, there's a good chance something *in* your license specifically says not to do this. You probably want to check.
Comment: What kind of developer software are you talking about?  It really depends on what you are trying to use.
Comment: Windows Server Terminal Services ?
Answer: While you can install Windows and other software in the cloud depending on what cloud service you use, you will need people to access the server that your software is on to use it.
In order to install software on a cloud or remote computer and give access to multiple developers, you will need to install multiple copies of Windows and multiple copies of the Developer Software, which defeats the purpose.  Otherwise, you will have multiple developers accessing one machines remotely which is no where near an ideal solution and probably won't even work like you want.  The only time this would make any sense, is if you have developers who have 0 overlap in work time.  Then you could have them use the same software.
Remember, if software costs money, then the people selling will probably not want to have a situation where someone can do an end run around their licensing scheme in order to save large quantities of money.
Another option is to look at what software you plan on using.  Many software IDEs are free and work well, like Eclipse.  Other like Visual Studio, cost a decent amount of money but there are cost effective solutions for them as well.  Specifically, MSDN licensing, which seems expensive at first but you get a large amount of software, including multiple versions of Windows and the cost drops off significantly after the first year.
Answer: You can use RDP to connect to a remote Windows instance and display it locally. The thin client can be another Windows machine, or a Linux machine that supports RDP.
Note that Windows XP does not support multiple logins via RDP, you will need Windows Server Edition for that.

Install software in the cloud


Behringer UCA202 Audio Interface and BEHRINGER C-1

Question: I need to be able to use a BEHRINGER C-1 mic in my PC, I need to know if a Behringer UCA202 Audio Interface will work for me, if you know any other interface that would help me a lot!
Answer: No it doesn't work. You will need a audiointerface with a phantom-powered XLR-input. I always recommend a better interface with good mic preamp for a clean record. The Focusrite Saffire 6 USB is a very nice interface for a good price.
Hope this answer is helpfully.
Answer: This one is bad for a mic use (no XLR and Mic preamps).
To stay in a low price range (a bit higher than the UCA202 though) you should prefer this kind of interface.
Scarlett Solo


Workflow task list - Add an additional column of information from a related list item

Question: A new request came up to me to have a task (in the default workflow tasks list, generated by a workflow) show an additional column next to the task's Title (column) which shows information from the Task's related list item. For example, I may have a Title of a task called "Review" (many tasks created to many different people for review) and then next to it need to have a column which contains a group or category for the review like "Engineering" for the specific task item. This would help the end users because they could see which group or category needs to review it, without this they would need to go into the task to see that level of detail. The reason this is needed is because there are many coordinators needing to review many tasks but only a subset of them are responsible for different groups or categories. Therefore they would like to be able to create views of their my task list to filter out unneeded groups or categories.
I have gone down a couple of rabbit holes and have been unable to fulfill the request above. I am hoping someone here has had some experience with this and could provide me some guidance. Thanks in advance!
Answer: If you want to show the information from the Task's related list item, you could create the lookup column to look up the items from related list.
If the lookup column cannot achieve your requirement, could you please provide more details about the issue?


Can you jump over an enemy?

Question: Assuming a +5 strength modifier and 10 feet of movement prior, can you jump over a medium sized creature to land on the other side?
Comment: Are you concerned about getting an Opportunity Attack?
Comment: Yes. I also have access to the jump spell
Comment: Is the PC a fighter(champion) of level 7 or higher?   If yes, that would influence the answer due to "remarkable athlete" and if no, then it would not.
Answer: Yes, in most cases

Half-orc 4'10" +2d10
Page 121 of the PHB

Half-orcs being the tallest medium creature in the PHB and their tallest they can get to is 6'6".

High Jump
When you make a high jump, you leap
into the air a number of feet equal to 3 + your Strength
modifier if you move at least 10 feet on foot immediately
before the jump. When you make a standing high jump,
you can jump only half that distance. Either way, each
foot you clear on the jump costs a foot of movement. In
som e circumstances, your DM might allow you to make
a Strength (Athletics) check to jump higher than you
normally can.
Page 182 of the PHB

Assuming a +5 str we would calculate 3'+5'=8' which is greater than the 6'6" of our half-orc.
Therefore unless your medium creature is a lot taller than usual, then there shouldn't be a problem.
Comment: @PinkSweetener yea they're still within 5 ft if they're above you
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/77843/discussion-on-answer-by-rpgstar-can-you-jump-over-an-enemy).
Comment: Huh, just realized that there's nothing in the rules preventing opportunity attacks against creatures that are above you.
Answer: Yes, when looking creature size; but not the space a creature controls
High Jumping
Performing a running high jump (like in the Olympics...but maybe without the Fosbury flop) would let you attempt to do this and that lets you: (PHB, 182):

When you make a high jump, you leap into the air a number of feet equal to 3 + your Strength modifier if you move at least 10 feet on foot immediately before the jump. When you make a standing high jump, you can jump only half that distance. Either way, each foot you clear on the jump costs a foot of movement. In some circumstances, your DM might allow you to make a Strength (Athletics) check to jump higher than you normally can.

Creature height
As long as the creature is 8' or less, you can jump over them. But you may risk an Opportunity Attack.
Controlled Space
With a strength modifier of 5, you can high jump 8'. In order to clear the controlled space of a Medium creature (5'), you need to be 10' away. Unless your DM allows you to make a strength check, you may be out of luck. The DC would likely be set keeping in mind the actual height of the creature.
If you CAN jump 10'
In order to 'clear' a medium creature that commands a 5' space, you need to:

Run 10' to let you add your strength modifier
Begin your Jump 5' before the target and land 5' after. Total of 10' of movement.
Jump 10' above the target.

This sums to 30' of movement. Most creatures have this as their Movement.
*Dwarfs who have magic items like the Boots of Speed can do this
Comment: You're forgetting the target himself takes up 5' so : Run 10' Jump 15' long (5' before, 5' over, and 5' after).
Jump 10' high.
You would need at least 35' of movement to avoid an attack of opportunity from the target.
Comment: This is a pretty comprehensive answer; the Fighter Champion, who at level 7 gets 'remarkable athlete' might have more success due to the bonuses to jumping that feature provides.  Consider adding that point, perhaps .... *when you make a running long jump, the distance
you can cover increases by a number of feet equal to your Strength modifier*
Comment: @KorvinStarmast That's for a running long jump, we're talking about high jumps here :)
Comment: I was under the impression that the two could be combined (in terms of the movement budget in re a dwarf?)  Maybe not.
Comment: @NautArch the question did not specify that you had to stay out of their attack range so you only have to avoid their 5' of controlled space not their 15' attack range for most melee attacks.
Answer: High Jump
Not without a house rule. High Jump mechanics only allow a character to move along the vertical axis. There are no rules providing for combining two jumps in a single movement or "walking" in a horizontal direction while high-jumping (depending on how you want to characterize it).
Long Jump (expanded answer)
@V2Blast reproduced the text of the long jump below. I suppose it could be construed as enabling a jump over an enemy--so long as a long jump's distance is at least four times the enemy's height. Given that a bipedal creature in the medium size category normally stands somewhere between 4-8 feet, a long jump covering 16-32 feet would be necessary to clear the head of such an enemy. That does seem possible, but perhaps not without significant magical assistance or some otherwise extraordinary character feature (Monk's Step of the Wind?). You'd also probably need a luxuriously spacious tactical map to allow for that much unimpeded horizontal movement in one direction.
Finally, the above may have the absurd side effect of being able to jump higher with a long jump than with a high jump.
Comment: There is a mention of jump height in [the rules for a long jump](https://roll20.net/compendium/dnd5e/Movement#toc_6), but that's it: "This rule assumes that the height of your jump doesn't matter, such as a jump across a stream or chasm. At your GM's option, you must succeed on a DC 10 Strength (Athletics) check to clear a low obstacle (no taller than a quarter of the jump's distance), such as a hedge or low wall. Otherwise, you hit it. "
Answer: In order to jump over a medium-sized creature without it getting an opportunity attack, you will have to be able to high jump about 12' for a medium opponent with a normal weapon (more for a bugbear, or if it has a reach weapon).  With a 10' running start, you can high jump 3'+your Str bonus, so that would still require a Strength bonus of +9, meaning a strength of 28.  Long jump limit, again with a 10' run up, would have to be a bit more than 15', which is relatively easy with a decent strength, since the long jump distance is the same as your Str score.  So height is the limiting factor, and to simply jump over (with a 10' run up) would basically require Storm Giant Strength.  Maybe a bit less if the opponent is on the short side, but still, for a normal character with a max strength of 20, the high jump limit is 8', which most medium opponents could reach and thus make an opportunity attack as you went over/past.  A small opponent you could probably clear with a 20 strength.
With a Jump spell, it is easy -- you'd need to jump up 4', tripled by the spell, which would require only a Str bonus of +1, or a 12 strength.  In this case, the long jump is g0ing to be limited by your movement rather than your strength.  With a 10' run up and a normal 30' movement, you will be able to jump 20' long (as long as you have at least a 7 strength), which is enough.  If you Dash as your action, that presents more options.
Answer: Yes.. but I would give them an attack of opportunity on you while you were doing so... unless you had some kind of shield skill + athletics to know how to position your shield between you and them in acrobatic fashion.
Just a brute-strength jump can get you over an enemy, but you may be flying through the air with your mid-section and vitals exposed. Enemy just pokes their sword / spear upwards and guts you.
Now, the bigger issue I see going on is that you're micro-managing combat too much. The whole point of role-playing is to abstract combat to make it flow, and then just story-tell / RP the end result of a couple of dice rolls... not micro-manage every move and then dream up all the extra rules that need to go with it to make it work. That just creates arguments and rules-lawyering.
Because if you have enough strength to jump over an enemy, why not just argue for bashing them aside to get behind them, or argue that a thief has enough dexterity to slide between their legs to get behind them.
The to-hit and damage rolls are supposed to abstract and handle all of this minutiae, that way players won't dream up crazy stuff then argue with the GM over the rules for it.
EG (good): roll to-hit.. you hit.. roll damage.. massive damage... story-tell how it happened... "you somersault over the orc, landing behind him and stabbing your sword behind you with one graceful blow... felling the opponent."
EG (bad):
(player) I want to jump over the enemy to try to get an attack of opportunity on him
(gm) Um.. ok.. I guess that would require you to roll a ...
(player) My strength has a +5 modifer
(gm) I was thinking more of a dex feat
(player) But I want to use strength, because it requires strength to jump
(gm) But it requires dexterity to somersault and land without twisting your ankle
(arguement continues, because you're trying to shoe-horn rules to fit an action, instead of dreaming up action that fits the post-rolled dice rolls that already account for both rules and abstraction of complex combat possibilities).

Can you jump over an enemy?


How should the prayers (salat) be performed in battlefield?

Question: How should the prayers (salat) be performed in battlefield? How about when one is bleeding? How about when one is on a mission and must complete the mission within a given time frame and don't get time to perform salat?
Answer: First of all, I suggest you to read the verses of Surah al-Nisa which are as shown in below (that are related to your question):

إِذَا ضَرَبْتُمْ فِي الْأَرْضِ فَلَيْسَ عَلَيْكُمْ جُنَاحٌ أَن
  تَقْصُرُوا مِنَ الصَّلَاةِ إِنْ خِفْتُمْ أَن يَفْتِنَكُمُ الَّذِينَ
  كَفَرُوا ۚ إِنَّ الْكَافِرِينَ كَانُوا لَكُمْ عَدُوًّا مُّبِينًا ﴿١٠١﴾
وَإِذَا كُنتَ فِيهِمْ فَأَقَمْتَ لَهُمُ الصَّلَاةَ فَلْتَقُمْ
  طَائِفَةٌ مِّنْهُم مَّعَكَ وَلْيَأْخُذُوا أَسْلِحَتَهُمْ فَإِذَا
  سَجَدُوا فَلْيَكُونُوا مِن وَرَائِكُمْ وَلْتَأْتِ طَائِفَةٌ أُخْرَىٰ
  لَمْ يُصَلُّوا فَلْيُصَلُّوا مَعَكَ وَلْيَأْخُذُوا حِذْرَهُمْ
  وَأَسْلِحَتَهُمْ ۗ وَدَّ الَّذِينَ كَفَرُوا لَوْ تَغْفُلُونَ عَنْ
  أَسْلِحَتِكُمْ وَأَمْتِعَتِكُمْ فَيَمِيلُونَ عَلَيْكُم مَّيْلَةً
  وَاحِدَةً ۚ وَلَا جُنَاحَ عَلَيْكُمْ إِن كَانَ بِكُمْ أَذًى مِّن
  مَّطَرٍ أَوْ كُنتُم مَّرْضَىٰ أَن تَضَعُوا أَسْلِحَتَكُمْ ۖ وَخُذُوا
  حِذْرَكُمْ ۗ إِنَّ اللَّـهَ أَعَدَّ لِلْكَافِرِينَ عَذَابًا مُّهِينًا
  ﴿١٠٢﴾
فَإِذَا قَضَيْتُمُ الصَّلَاةَ فَاذْكُرُوا اللَّـهَ قِيَامًا وَقُعُودًا
  وَعَلَىٰ جُنُوبِكُمْ ۚ فَإِذَا اطْمَأْنَنتُمْ فَأَقِيمُوا الصَّلَاةَ ۚ
  إِنَّ الصَّلَاةَ كَانَتْ عَلَى الْمُؤْمِنِينَ كِتَابًا مَّوْقُوتًا
  ﴿١٠٣﴾
And when you travel throughout the land, there is no blame upon you
  for shortening the prayer, [especially] if you fear that those who
  disbelieve may disrupt [or attack] you. Indeed, the disbelievers are
  ever to you a clear enemy. (101)
And when you are among them and lead them in prayer, let a group of
  them stand [in prayer] with you and let them carry their arms. And
  when they have prostrated, let them be [in position] behind you and
  have the other group come forward which has not [yet] prayed and let
  them pray with you, taking precaution and carrying their arms. Those
  who disbelieve wish that you would neglect your weapons and your
  baggage so they could come down upon you in one [single] attack. But
  there is no blame upon you, if you are troubled by rain or are ill,
  for putting down your arms, but take precaution. Indeed, Allah has
  prepared for the disbelievers a humiliating punishment. (102)
And when you have completed the prayer, remember Allah standing,
  sitting, or [lying] on your sides. But when you become secure,
  re-establish [regular] prayer. Indeed, prayer has been decreed upon
  the believers a decree of specified times. (103)

Of course it has not illustrated in detail, but in according to the Sunnah of the prophet Mohammad (SAWW) (from the view of Shia) :

The prayers which are 4Rek'ahs, they will change to 2Rek'ahs. The
  first group do a Rek'ah with the Imam, and the Imam will be stop after
  the first Rek'ah, and that group will do the other Rek'ah lonely and
  will come back to the war, afterwards the second group will go to
  their place and do a Rek'ah of their prayer with the Imam and do the
  second Rek'ah lonely.
Tafseer-e-Nemune, Volume4, page103.

Of course there are other views regarding the circumstances of it, but it was the most famous of them.

Source:
www.askdin.com
Comment: 1+ for quoting the Quran Verses and the way prayer is performed
Answer:
There's no specific prayed mentioned particularly during battle except the prayer of fear, or salatul khawf.

It's collected in both Bukhari and Muslim, that during the battle of Dhat Riqa:
"... a group formed a row and prayed along with him (the Prophet), and a group faced the enemy. He led the group which was along with him in a rak'ah, then remained standing while they finished the prayer by themselves. Then they departed and formed a row facing the enemy. Then the second group came and he led them in the remaining rak'ah, after which he remained seated while they finished the prayer themselves. He then led them in salutation."
The prayers are shortened during battle.

There's no prayer prescribed while one is bleeding.
The prayer can be shortened depending on the travel length.

Allaho Alim


Replacement for 2N6027

Question: I am working my way through Make: Electronics. For some experiments in this book, you need a 2N6027 programmable unijunction transistor (PUT). The shop I am buying my parts from doesn't have this exact model, but the 2N6028. The combined datasheet for both models shows some differences. I am wondering whether they are similar enough for simple experiments are whether I should try finding another one that matches the 2N6027.
Comment: It's disappointing that a modern book about electronics would spend ink on an obsolete, hard-to-find part like the UJT.  Do they talk about tunnel diodes, too?
Comment: I'm in the same situation with that book, there's a critical series of 'recipes' in the first section of the book that rely on this rare chip. As R. McMahon mentions below, I guess we'll learn more than expected on the way.
Comment: There are specific applications where a Programmable Unijunction Transistor is useful.  Driving large SCRs is one such application - the peak current from a UJT is sufficiently large that you don't need a separate driver stage to properly fire the SCR.
Comment: Nope. No tunnel diodes.
Answer: They share the same datasheet, and I think the differences almost certainly won't affect the experiment (oscillator?)
The only significant difference I can see is the peak current on the 2N6028 is lower, which means it will turn on a bit sooner. If set up as an oscillator I think this will just produce a lower amplitude waveform.
Disclaimer - I have only used one of these once a long time ago (almost unheard of nowadays) so I wouldn't put this in writing (er, hang on...)
Comment: FYI, I ordered the 2N6028 in the end and the experiment in the book worked just fine.
Comment: Yep, it's for some sort of oscillator. They are pretty cheap so I will try using the 2N6028.
Answer: A good tool is www.findchips.com. Both mouser and digikey stock the 2N6027, and it is cheap for such an old beast. www.reichelt.de is even cheaper. If you don't want to go out of the country: I sell the 2n2646: http://www.voti.nl/winkel/p/T-2N2646.html .
Answer: Digikey has both in stock.
 I see you are in the Netherlands - I don't know how accessible Digikey is there.
2N6027. ~ 27000 in stock at $US0.48.1
2N6028, 16000 in stock. $US0.48/1
Datasheet for both is here from ONSemi.
As Oli notes, the peak currents are different.
The 2N6028 peak current is about 10% of that for the 2N6027.
 This would make major differences in resistance or capacitance or time values in a given circuit. Definitely usable but you may learn a bit more than expected along the way :-).
Other parameters vary between the two parts but are probably close enough so as not to make a major difference.
UJTs are interesting devices and well worth knowing about, and you can do some fun things with them that are not easily done with other single devices - but they are relatively little used in modern circuits.
Comment: Digikey in the Netherlands is no problem, at least not for me (company, large order), but be prepared to provide detail on everything you want to do with every resistor :( Mouser has this component too, a little cheaper, and they don't ask crazy questions.
Answer: You have many "easy to find in stores" replacements / equivalents for the 2N6027 PUT (Programmable Unijunction Transistor).
The following are the replacement parts listed in www.icreplacements.com:
2N6116
2N6119
MPU131
MPU231
SK3628
Hope it helps you to finish your project. :)
Complete information source:
http://www.icreplacements.com/2/2N6027-replacement-compatible-PUT_--Programmable_Unijunction_Transistor---substitute-equivalent-part-cross-reference.htm
Answer: I've encountered a similar problem, but the local shop doesn't carry the 2N6028 either. They do carry the the NTE 6402 (TO-92/TO-98), however.
Looking at the data sheet, compared to that for the 2N6027, I think that the NTE 6402 could serve as an equivalent replacement component. I'd be happy to let anyone check my work on that, though.
Answer: The dutch ( in Groningen) store okaphone sells the 2N6027 http://www.okaphone.nl/ for 95 euro cents  piece. they also have a webstore order.

Replacement for 2N6027


Entity Bean finder methods VS DAO?

Question: Will there be a performance improvement if I remove the entity bean (finder methods) and introduce the DAO layer instead. I want to do this mainly for reading data from the DB. I have a process in my project which has around 15 entity beans finder call in the flow, so if I remove the Entity beans or introduce a DAO and leave the entity beans as it is will there be a significant improvement in the performance ? I am using EJB 2.1.
Answer: Retrieving data by using Entity Bean finders loads all of the attributes for the entity, even when you might only need the value of one of them for the task at hand. So, indeed, EJB finders methods have overhead and this is especially true when retrieving large data sets (not even to mention when you are invoking 15 of them).
So, to retrieve large read-only data sets, it may indeed be preferable to talk to the database directly from the Session Bean (I guess that you have a Session Bean facade) using JDBC API. This pattern is known as Fast Lane Reader if I remember well.
Just keep in mind that implementations of this pattern sacrifice data consistency for performance, since queries performed at the raw JDBC level do not "see" pending changes made to business information represented by Enterprise Beans.

Entity Bean finder methods VS DAO?


Can any hard drive of the same format be put into a hot-swap tray?

Question: I'm looking at buying a hot-swap NAS that supports SATA/SATA II hard drives.  Can I get any SATA drive and put it into the hot-swap trays it comes with, or will I need to find a certain kind of drive?
Answer: Normaly any SATA I/II you can found in the markey will fit in. Check you NAS documentation to see if there some limitation about it.
Hope this help.
Answer: Any on the NAS drive's HCL will do. If you tell us which models you're looking at or have bought we could help you get the best out of it.
Comment: I was looking at the Netgear ReadyNAS 1100

http://www.cdw.com/shop/products/default.aspx?EDC=1356393
Comment: Maybe you could add that to the question at the top.
Answer: Typically, the hotswap drive needs to be essentially identical to the drive it is replacing, but every system is different.
Some systems can support swapping in a bigger drive with similar characteristics, with the excess space being unusable.  Certainly, it can't be smaller than the drive it is replacing.  I imagine that the tolerance for similar but bigger drives would be discussed in the technical specs of the system, or can be obtained from the company support mechanisms.
One of the very unique features of the Drobo system is that it can handle size and flavor of drives.
Comment: I think Jeffrey's NAS is empty to start with, and he's wondering which drives he can buy.
Comment: The capacity of the drive is only an issue in once case - you can't replace a larger with a smaller drive. However if they are in an array, you also will loose any expanded capacity because that can't be replicated across all of the the members of the array.
Answer: Your NAS solution may have only been tested with a particular kind of drive, including firmware version. It may have custom firmware.
You will have to trust the manufacturer's advice about supported drives. Even though they may deliberately deceive you so that they exclusively can sell you overpriced drives, there's no way to determine whether this is the case or whether there is a good reason for a particular drive.
Most flaky SATA solutions I've seen have problems due to interactions between drives and the controller. A drive that the controller vendor never tested is asking for more problems.
If it's a very low-end NAS solution, the problems caused by the NAS itself will probably eclipse any problems caused by drive/controller compatibility. And it is unlikely that there is custom firmware, or even serious testing of drives by the vendor.


What is the "difficulty bomb" and what is the goal of it?

Question: The difficulty bomb is related to the switch to proof of stake. How does it work exactly and why is it going to help to switch to proof of stake?
Answer: The difficulty bomb is a part of the consensus algorithm; its goal is to make the difficulty of mining a block arbitrarily hard at some point in the future. When active, it will get increasingly hard for miners to create new blocks and therefore will get block rewards less frequently; which means less revenues. Exponentially.
From the blog:

starting from block 200,000 (very roughly 17 days from now), the difficulty will undergo an exponential increase which will only become noticeable in about a year.

This is a very strong incentive to rapidly switch to the new network.
Comment: While this functionality was originally proposed to be implemented as smart contract, that is not the actual case anymore. Instead there is a difficulty adjustment scheme as part of the client consensus algorithm, as further  explained on https://blog.ethereum.org/2015/08/04/ethereum-protocol-update-1/
Comment: Is there any other reason for creating dificulty bomb other than creating incentive to switch to PoS?