What is the purpose of answers to metaphysical questions?

Question: Generally speaking, metaphysics seems to deal with questions that cannot be verified empirically, which are thus beyond the understanding of science. Because of this I'm wondering whether the answers metaphysics provides to these questions are in any way useful. Whether the substantivist or relativism account for space is correct, why is the answer useful?
Comment: Huckleberry Finn can't be verified scientifically...does this mean its utility is zero, or negative?
Comment: Mozibur- I'd be interested to know what you mean by "utility".
Comment: @jimpliciter: its usual sense as  in a dictionary.
Answer: Your question really has two parts: (1) what can we know about metaphysics? (2) given what we can know, how can that stuff be useful?

metaphysics seems to deal with questions that cannot be verified empirically, which are thus beyond the understanding of science

A few philosophers that I've read have made a distinction that seems to get lost here, the distinction between using empirical evidence and the scientific method. As one example: CS Lewis in Mere Christianity uses the example of certain personal experiences that we all share and tries to extrapolate metaphysical concepts about right and wrong. These personal experiences are the data upon which he builds the argument, but these experiences being personal are not "reproducible" in the scientific sense.
Taking CS Lewis's example also shows the potential use in metaphysics: it is a metaphysical, and not scientific question, whether morality is objective or relative, and so as a consequence what is and is not moral, and from that how a just society should (and should not) be structured. Seems useful to me.
Answer: Aristotle, who wrote a book which was later called metaphysics; and which then meant after the Physics, another book of his; said that this discipline explores the first principles of things. Physics in his sense is wider than the notion we have today; and its important that that this study comes after and not before; being more difficult, more abstract and much more uncertain; and this comes through in his discussion of the positions of different philosophers, as well as his own commentary on them.
Hume, who is often seen as the most severe of sceptics, defends in an Enquiry Concerning Human Understanding, the more difficult and profound study - Metaphysics against the friends of the 'easy philosophy' who are apt to pour scorn on it. Easy here, isn't a pejorative label - in fact Hume says the easy philosophy enjoys its fame for good reason; and nor should it be seen as easy, it too can be difficult in a different way.
Comment: Your answer is great. I know what you mean by Hume's "easy philosophy" here...can I smile.
Comment: So Hume is "enjoying" too, the "easy philosophy", am I right? Actually up until the appearance of the Julien Offray de La Mettrie, the book of the "difficult site" even I must include Hume, is difficult, other term, ambiguous to read... sorry to say that.
Comment: I thought you tried to "level" the balance between the "difficult philosophy" and  the "easy philosophy". However, yes, the "easy philosophy"  is **in the way which even 18th century's de la Mettrie's question has no been solved yet by anybody, intrinsically**, it is still "easy" to read, while the opposite side's  are "hard" to comprehend ( as if they are, personally, playing with the words to me.)
Comment: Man A Machine : https://www.marxists.org/reference/archive/la-mettrie/1748/man-machine.htm
Answer: You seem to claim that something that cannot be verified empirically is beyond the understanding of science and probably not useful.
Mathematics cannot be verified empirically, but is very helpful. Why do I think that mathematics cannot be verified empirically? First of all, it is an open question what mathematics is about. Whatever numbers are, a lot of them, indeed, infinitely many of them, are larger than the amount of stuff in the universe.
(Of course, there are philosophers, and especially metaphysicians, that work on those questions. Some think that mathematics can be verified empirically, see for example Maddy)
One branch of metaphysics is modality. Something is science, you seem to suggest, if it makes verifiable claims. Which is just to say that it has to be possible to verify it. The nature of possibility belongs in the realm of metaphysics. And working on modality helps us to pin down what is verifiable and what is not. If that is your demarcationline between science and non-science, working on metaphysics is useful.
Furthermore, I don't think that your claim is true in the first place. Science, for example theoretical physics, makes claims that are not empirically verifiable (at least not yet). Example: Theoretical Physics makes assumptions about what is in a black hole, but it is impossible for us to go into a black hole and make our observations. But theoretical physics is still useful I'd say.
Comment: So according you, if someone puts a faith in something, it is only because so.?
Comment: And mathematics is historical. The development of how to measure the **size** ( accordingly derived the length, width, and the method to calculate ) was because the landlords in feudal area required which land belongs to which landlord. That would mean, I would like to say, a human conduct origin not God given.
Comment: When I say **God given** and that was quite unrelated with your opinion, I am sorry. Only what I wanted to say is, as you said, mathematics may be empirically verifiable should it be **historical**.
Comment: Or, along the lines of Maddy et al, mathematics is empirically verifiable because sets are located in space-time and can be observed.
Comment: Thank you for your comment. Though I understand what you say, due to the lack of the terminology of mathematics, I can not go deep further. Simply, I may be able to say simple Y=X(n) could be comprehend as time-space relationship like the theory of universe when we take X as time and Y as space.
Answer: I quite agree ( meaning, you seem to be doubtful about the usefulness of the metaphysics ), even though as Kant claims humans can never have direct access to reality, employing such a method like Edmund Husserl's phenomenology, which is the analysis like peeling the outside layer of the target object layer by layer, even though we can not have direct access to the object itself, we can scientifically analyze the nature or the subjective phenomenon as far as we can conduct the analysis. ( Thus we can reach to the object itself closer and closer. ) It is, actually, a branch of materialism in its nature, to me, personally. Metaphysics, on the other hand, are just difficult even to read their theories or whatever.
Feurbach also argued why Greek deity look like Greeks?  He said it is because that Greeks at that age only were able to deduct their own image of God because they were able to look at the quite limited periphery. If then, should there be such a thing like Universal God, that would not be God, I think, but only a hole unknown which is unverifiable to anyone which nobody can put their faith in. I am sorry for my poor English.

A quote from Man A Machine I commented on Mozibur Ullah's answer.
To distrust the knowledge that can be drawn from the study of animated bodies, is to regard nature and revelation as two contraries which destroy each other, and consequently to dare uphold the absurd doctrine, that God contradicts Himself in His various works and deceives us.If there is a revelation, it cannot then contradict nature. By nature only can we understand the meaning of the words of the Gospel, of which experience is the only truly interpreter.
This is a speech from a 18th century's "philosopher", my friends!. How are we still "discussing" such a same issue. Personally, this is not related with the questioner's question, but we human beings have nod advanced so much from, to say, since latest around the early 20th century. Jaccues Derrida's Spectres of Marx, in which he claimed he "would like to?" be the inheritor of Marx, is, after having read, I thought it was a poem not a thesis or anything.
Answer: I'm not sure I understand the motivation for the question. The purpose of an answer is to answer the question. If the answer is 'beyond science' this doesn't mean it's beyond the understanding of scientists. Scientists are not necessarily any worse than philosophers at understanding metaphysics, given the same amount of effort to do so.
Assuming it is correct, how could an answer to a metaphysical question not be useful? Such questions are isomorphic and holographic thus (as Heidegger points out) the answer to one would be the answer to them all. How could it not be useful?
You cite two possible answers for questions about space and ask why they are useful. This is not a relevant question unless you can show one of the answers is correct.
I would suggest you have a false impression of metaphysics. Wrong answers are not useful, (albeit discovering they are wrong is), but correct answers will allow us to understand the world better. Surely it would be useful to know the origin of the laws of physics, the nature of space and time, the truth about consciousness and so forth.
We could probably agree that an incorrect answer to a metaphysical question will be useless but we cannot judge the usefulness of the correct answer until we know what it is. In Western thought it would be almost heretical to suggest that we could know the answer to a metaphysical question so you may be thinking only of this approach to metaphysics. Most of its champions insist that metaphysics does not produce answers so their usefulness is not investigated, discussed or known.
Speaking personally, taking up the study of metaphysics has turned out to be one of the most useful things I've ever done.
Answer: One can use the information contained in a map to assist in navigational activities within the territory the map is assumed to be a reliable representation of. One can use assembly instructions for the guidance required to piece together flat packed furniture. One makes a shopping list to alleviate the need to remember and to optimise expenditure. One uses signage to help find the location of the toilets in an unfamiliar shopping precinct. One uses the step-by-step procedure in the auto workshop manual to facilitate a coolant/oil/filter change on the car. One uses a recipe to cook an unfamiliar meal- the list is endless.
Generally speaking, If a representation R contains genuine and useful information about some target system E, then R can be used to 'leverage' (inform/guide/coordinate/instruct/organise/regulate/navigate/anticipate/prepare/etc.) one's interactions with E (R is used to guide or correct for minor 'cognitive deficits' pertaining to E-interactions). If R doesn't provide this, then R is redundant or worst impedimental. Metaphysics has no utility in this sense and I challenge anyone on this site to provide an obvious counter example that doesn't trot out some clap trap about 'understanding'. Pace Logical Positivism, I think the significance of what you might call "the social utility of representation" is however, hopelessly over looked.
Metaphysics seems to consist in little more than a pretence to 'reality tracking' when the only thing that's really going on is 'social coordination' among only those privileged and versed enough to occupy the upper/inner echelons (much like the Catholic church for example). Think of the notion of 'latent vs. manifest' function from sociology. The manifest function here would be to get a grip on what reality is and does and to have that adequately communicated amongst ones interlocutors. The latent function is to reap the residual (perlocutionary, J.L. Austin) social benefits- to get along with this philosopher (camp), make each other feel good, solidarity, trust, inclusion, etc.; or the opposite -to antagonise, show defiance, annoy, exclusion, etc., tenure, grants, publishing notoriety and so on.
This 'social' phenomenon is rather ubiquitous. We're all guilty of using a pretence to (or assumption of) reality tracking as a way (mode) of subserving social interaction on a quotidian basis: conversations involving putative topics, news, anecdotes, fables, hot and cold gossip, rumour/hearsay, jokes/comedy, conspiracy, propaganda, errant or extreme values, myths, superstition, religion, mysticism, spirituality, misconception, bigotry, ignorance, white lies, sub cultural norms…, much of what counts as philosophy, etc. It's a group based (pragmatic) strategy that gets you access to all the latent goodies that come with being socially hooked up with people who are supposedly 'on the same page' and separated from those that aren't.
"…, a merely random groping, and, what is worst of all, a groping among mere concepts."- Immanuel Kant, (Critique of Pure reason).
Comment: can you format your text so that it's easier to read?


Windows 7 machines can't ping or access Windows Server 2003

Question: Our network is served by a Windows 2003 Server machine, using Active Directory for users security management. There are more than 60 machines connected on a daily basis and most of our files are stored on the server. Everyone worked normally everyday, until today.
Today we started having this very weird problem: all Windows 7 clients can't even ping the server properly. We have already restarted the server (a dreadful thing here) to no avail. We've checked all possible logs in the Event Viewer but had no clue as to what is happenning. We noticed that the ping behaves specifically: the first ping succeeds but the other three don't. Here's the image:

On the Windows XP machines all goes safe and sound, people accessing the shares and computers normally.
Any ideas?
Answer: Seems like the problem is with the server.
Hitting Windows > Run and running NETDIAG /fix ON THE SERVER solved the problem.
Answer: Just had the exact same scenario.
Also, along with these symptoms we found that the Windows 7 computers could successfully pull a DHCP address from the 2003 server and it even showed up in the DHCP lease table, but the computers still could not ping the server.  When viewing the ARP tables on the Windows 7 computers we found that the IP of the server was listed twice and each instance had a different MAC address.
This turned out to be caused by the ARP proxy on the inside interface of our ASA5505.  When ARP proxy was disabled, our three new Windows 7 machines immediately started talking to the server.


Theorem on any 2-dimensional riemannian manifold conformally flat

Question: I found a theorem stating that "Any two-dimensional Riemannian manifold is conformally flat". Here the flat metric seems like the metric $g_{ab}=diag(-1,1)$. However, the normal Euclidean space $\mathbb{R}^2$ with the metric $g_{ab}=diag(1,1)$ cannot be conformally flat. So what is the exact meaning of this theorem? Could anyone please explain?
Answer: In the context of Riemannian (not pseudo-Riemannian or Lorentzian) geometry, flat means locally isometric to the Euclidean metric $\mathrm{diag}(1,1).$ The indefinite metric $\mathrm{diag}(-1,1)$ is not Riemannian, so of course no Riemannian metric will be locally isometric to it.
Comment: Then the above theorem holds with $diag(-1,1)$ for any two-dimensinal "pseudo"-Riemannian or "Lorentzian" manifold?
Comment: Because the context of the theorem above is http://ion.uwinnipeg.ca/~vincent/4500.6-001/Cosmology/WeylTensor.htm#ZEqnNum455720 (the theorem on the bottom)
Comment: Yes, this result is also true for Lorentzian surfaces. The source you link is confusing, since it defines conformal flatness only in the context of Lorentzian geometry, but then states the theorem for a Riemannian metric.
Comment: OK, let us summarize. The Riemannian surfaces are conformally flat where the flat metric  is $diag(1,1)$. The Lorentzian surfaces are conformally flat where the flat metric is $diag(-1,1)$. Is this right?


What is the difference between the CCA weights and rotations?

Question: I have been looking at the scikit learn Canonical Correlation Analysis (CCA) algorithm, and I have come across the terms "weights" and "rotations" as parameters of the CCA model. What is the difference between the CCA weights and rotations, and how are they related to each other?
Answer: From the scikit-learn documentation for Canonical Correlation Analysis (CCA):

x_weights_ … The left singular vectors of the cross-covariance matrices of each iteration.

x_rotations_ … The projection matrix used to transform X.

There are similar attributes for y.


How do I use investments to lower my taxes [US]?

Question: I'm not sure how this works. Do you just report on your taxes which investments you contributed to during that year, and then get a deduction?
I want to pay less taxes, and put my income in some investments at the same time. Where should I start?
Answer: Not exactly. There are a few ways to manage your taxes with investments.
1) For most investments you get taxed on any gain in value in the investment or dividends paid by that investment. Most investments (with some exceptions for mutual funds) you don't take the tax hit until you sell the investment and realize the gain. For bonds, cds, and other cash type investments you have to pay taxes in the year they pay out the interest or dividend.
2) You can put money (up to a certain limit) in a traditional IRA and can subtract that amount from your income for tax calculation for the year you invest it. However, you are going to pay taxes on it when you take the money out at retirement. It really just delays the taxes.
3) If you put the money in a Roth IRA, you don't get a tax break now, but you don't have to pay any taxes on the money or the gains when you take it out at retirement.
4) The gains from some mutual funds can be tax exempt, but that just saves you from paying tax on the increase in value.
5) Don't fall for scams that try to use insurance policies as investments to avoid taxes. The fees are ginormous, which usually makes them a ripoff.
Comment: I don't think #1 is accurate for mutual funds.  Many mutual funds will pass on capital gains taxes to you as the fund manager sells and buys investments during the year, even if you didn't realize any dividends or gains payouts.  (You can end up paying a gains tax for the year, even if the fund loses value.)
Comment: You are correct, fixed my answer.
Answer: Probably the biggest tax-deferment available to US workers is through employee-sponsored investment plans like the 401k.  If you meet the income limits, you could also use a Traditional IRA if you do not have a 401k at work.  But keep in mind that you are really just deferring taxes here.  The US Government will eventually get their due. :)
One way which you may find interesting is by using 529 plans, or other college investment plans, to save for your child's (or your) college expenses.  Generally, contributions up to a certain amount are deductible on your state taxes, and are exempt from Federal and State taxes when used for qualifying education expenses.  The state deduction can lower your taxes and help you save for college for your children, if that is a desire of yours.
Answer: Consider the individual who pays $1,000,000 in taxes.  His/her income must be substantial.  That is what one should aim for.  Investments for the most part, do not lower ones taxes.
In one of John Grisham's novels, tax shelters are being discussed.  Sorry, I do not remember which book.  The discussion goes something like this:

lawyer 1:  can we do this?
lawyer 2:  do you mean "can we win in court if this is challenged?"
lawyer 1:  I mean "will we go to jail if we lose the challenge?"

There are a few investments which can lower your taxes.  Purchase a house.  Mortgage interest on your principle residence is deductible (if you itemize deductions).  If you don't itemize, focus on increasing income to the point where itemizing benefits you.
In general, businesses have more deductions than individuals.  Own a small business. You (or your accountant) will discover many deductions.  Hint: the company should lease a car/truck, many meals are now deductible.  This is not the reason to own a business.


Exchange Resource Scheduling Display Screen

Question: One of my clients is requesting an LCD screen outside of their conference room displaying the availability of that Exchange Room Resource.  Does anybody know of an easy way to do this?  I've found a few products that sync/integrate into Exchange for scheduling (Netsimplicity, PeopleCube, etc).  However, I'd like something that just interfaces with outlook and displays what the users have scheduled.  I mean, I could almost use Outlook if I could automatically refresh the display..
Answer: I was briefly looking into this idea some time ago and came across this page.  We ultimately decided against pursuing the idea when the people asking about it decided it wasn't worth the cost.
Answer: I'm sure these people would like to sell you something: http://www.visix.com/axistv.html
(Disclaimer: I found them via web search and have no idea whether or not they're good, bad, or indifferent.)


Change Armor Stands Pose with commands

Question: I have a map on Java 1.20.1 and I'm making it have a cashier (armor stand, in a store). And I want it to move to the block to its left and then its arms up & down at different times so it looks like it's typing on the register, and then it goes back to its original position, with arms back to the original pose. How would I do that?
Answer: You can change the pose of an armor stand using the /data command.
You can also use this website to generate armor stand poses.
A typing animation would look like this (with each line being in a separate command block or delayed in some other way):
/data merge entity <selector> {Pose:{LeftArm:[283f,0f,0f],RightArm:[305f,0f,0f]}}
/data merge entity <selector> {Pose:{LeftArm:[305f,0f,0f],RightArm:[283f,0f,0f]}}

The entity can be moved by using the teleport command (which I assume you already know how to use, since it's elementary).
tp <selector> <desired coordinates>

Change Armor Stands Pose with commands


Is Xcode 4 ready for iOS development or still too beta?

Question: I am just starting iOS/iPhone development and I would like to start using XCode 4 instead of XCode 3.2. Is XCode 4 stable/feature complete enough for beginning iPhone development or should I stick with XCode 3.2?
Answer: I have run into far too many problems using beta versions of XCode, especially since you can't really have two versions of XCode one the same system. Apple already has a history of releasing things to developers before they are truly ready (just look at iAds for the iPad which were released months ago and have yet to deliver a single ad). So, if even Apple isn't ready to label XCode 4 as ready-to-go then you can rest assured its not really ready to go.
I recommend sticking with 3.2. That's what I'm doing until XCode 4 is officially supported.
Using XCode 4 calls everything you do into question. Having a problem with an API? Maybe it's XCode, maybe its your code, maybe its a bug in the API. You just don't know.
Comment: +1 The official line (from the preview 6 read me) is: "Xcode 4 is beta software. Continue to use Xcode 3.2.x for production development.". To do otherwise would be extremely foolhardy as you've outlined above.
Answer: I would say no, it's not ready.  I tried using it as my main development environment for about a week, and eventually switched back to 3.2.  For one thing it crashed fairly regularly, but I could get passed that.
The big thing that caused me to switch back was a bug where the iOS simulator would think that certain resources existed in my app that didn't.  Deleting the app from the simulator didn't work, cleaning the project didn't work, and deleting the derived data folder didn't work.  Since it's not officially released, finding help for problems like this is a pain as well.
This is just one instance of the kind of problems you'll run into while using it, so I'd recommend avoiding it for now.
Answer: You can use Xcode 4 if you do not plan on using the current version (Preview 6) for submitting apps to the App Store.
iOS Dev Center:

Xcode 4 Developer Preview 6 includes
  iOS SDK 4.2, bug fixes, and additional
  features. To compile submissions for
  the App Store, continue to use Xcode
  3.2.5 and iOS SDK 4.2.


location of the resampled data from SMOTE

Question: I am using SMOTE in Python to perform oversampling of the minor class in an unbalanced dataset. I would like to know the way SMOTE formats its output, that is, whether SMOTE concatenates the newly generated samples to the end of the input data and returns that as the output or whether the new synthetic data points are positioned randomly among the input data points. I'd appreciate your help.
Answer: SMOTE is an algorithm used to generate " synthesize" new samples from the real samples.
It selects randomly one of the k-nearest neighbors, find the distance between these two pints , synthesize new point by modifying the sample considering the distance and a random number between 0 and 1.
SMOTE algorithm does not use samples from majority class only samples from minority.
It synthesizes new samples
It expects a high density minor class with small variation within the class
Anything else is related to the implementation, many implementation return only the synthesized samples
Comment: thanks! i am aware of the way SMOTE works, and my question was only with regard to the inner working of its Python implementation in the package imbalanced-learn. thanks for the description though.
Answer: There is not that much package managing the under-/over-sampling in python. So if you are using imbalanced-learn, it will return a numpy array which concatenate the original imbalanced set with the generated new samples in the minority class.
Comment: I am indeed using the imbalanced-learn package, and that's what i got from the code. i just wanted to make sure that i correctly understood it. thanks for your help :)


Which martial arts exercise helps to reduce weight?

Question: I am almost 100 Kg or 220 lbs. My height is 5 ft 9 inches. I do everyday gymimg for almost 70-80 mins. Can anyone suggest me some videos or links which combines both weight loss along with getting good at martial arts ?
Comment: Do you want to actually go to a martial arts school to train, or do you mean that you want to add something to your gym experience in solo? Like maybe your gym has an aerobics room that lets you do stuff, and you see yourself learning some martial arts workout routines from video and doing them by yourself at your gym?
Comment: I would like to add something in my Gym workout . I do punch & throw kicks to punching Bags move around like Boxers which I feel sheds more calories compared to a Cardio exercise on a Tread Mill or Elliptical . That's the reason I was looking for any other .
Comment: If you add some kicking to your moving "around like boxers" you'll burn more calories.  Low turning kicks are the easiest technique to deliver vaguely passably.  But you won't get *good* at martial arts unless you join a dedicated martial arts class and take the time to learn and understand the technique; no matter what art you pick, not all *that* practice will be cardio intensive.  Kyokushin big-mitt training is a great cardio workout too, but you'd need a partner to hold the mitt and would be best off joining a dojo for that.
Comment: Might want to migrate to sports/health.  Exercise reduces weight. There is no magic exercise.  Your weight is the calories you take in minus the calories you burn in activity.
Answer: Weight loss is highly individualistic. What works for some doesn't work for others, and vice-versa.
Consistency is the most important thing when it comes to exercise and health in general. So if you can find something you really enjoy doing, it makes it much more likely you'll continue doing it day after day.
Unlike some others here, I'm not going to suggest that martial arts practice is unsuitable for weight loss, because it can be used for exactly that purpose. And for some people, martial arts is more than just exercise. It becomes recreational, interesting, and continuously challenging.
That satisfies the main requirement that I mentioned above: Consistency. If it's something you enjoy doing, you'll keep doing it.
In general, weight loss is a combination of exercise and diet. Everyone knows that. That's no secret. And what most people also realize is that you need both in order to lose weight reliably.
Yes, you can just exercise alone or just diet alone and not both together, but eventually most people with that approach find that their weight loss plateaus. They might lose a ton of weight at first, and then it gradually becomes less and less. At some point they just stop losing weight altogether. When weight loss stops, it can be frustrating enough to go back to eating more and not exercising, and then the weight comes back really fast.
So the key thing to take from this is that exercise and diet must both be controlled if weight loss is to happen reliably. Both have their own issues and require some planning, and trial and error.
As for diet, there are plenty of approaches. It can be pretty overwhelming trying to choose one that works for you. So I won't say anything about any particular diet. I'll just say that successful dieters generally eat 3 meals a day, don't skip meals, don't starve themselves, limit their portion sizes, and cut out junk food, colas, and candy.
They also enjoy their diet. It shouldn't be something that requires tremendous willpower. If eating salads is your idea of torture, then don't do diets where salads are the main course.
If you want to go above and beyond that, start counting calories and limit yourself to some number of calories per day. There are calculators online for figuring out exactly how many calories you should eat in order to lose weight. But for most people, simply controlling portion sizes and not eating crap will suffice. The easier it is to follow, the less likely you'll stop doing it.
Okay, that brings me to exercise. Exercise can be aerobic or anaerobic. It can be all cardio and no resistance. It can be all resistance (strength) and no cardio. It can be sporadic (work and rest cycles). Or it can be continuous. And it can be any combination of these, or somewhere in between.
Which exercise is best for weight loss?
The answer is that it depends on a number of things. First and foremost is how much time you have in your schedule to workout. If you have just 30 minutes a day to workout, or maybe an hour every other day, then that says you probably need to think about getting the most calories burned per minute. For that, you'll want to do something akin to High Intensity Interval Training.
Then again, another factor is how fast you want to burn your fat. If you're okay with losing just a small amount of weight per month, then you might be able to accomplish that by just sticking with a lower intensity workout, such as strength training (weightlifting) or riding an exercise bike at a rate that doesn't cause much of a sweat.
You can try whatever you like first. Such as martial arts practice. So long as you're continuing to lose weight over time at the rate you want, you're fine. Increase your intensity if you see yourself plateauing or even gaining weight over time. Or change your exercise completely. It involves some trial and error.
Martial arts practice actually does fit this description pretty well. You can adapt it to a high intensity interval workout very easily. Or it can be light and continuous. This includes exercises like punching and kicking to a bag or even to the air.
Jumping rope is something you can take right out of boxing training, and there are videos on how boxers jump rope. There are grappling exercises as well that can be done, such as shrimping, weighted sled, tire rolling, walking on all fours across the floor, climbing rope, etc.
Take a look at the warm-up exercises that Gracie Jiujitsu or MMA gyms do and repeat the ones you find interesting.
There are also kata / forms. Karate, Taekwondo, and Kung-Fu have them. You can maybe learn one from video and repeat, repeat, repeat.
The good thing about forms is that after you repeat one maybe 100 times, it will be committed to memory. You won't have to think much about what you're doing. At that point, you're just trying to go as fast as you can and repeat it as many times as you can in a row before you collapse. It becomes a nice, compact workout program you can whip out whenever and wherever you are.
Movements in forms exercise a lot of muscles that are often neglected in traditional exercise programs. It can be intense at first. You might find your legs shaking after doing them. And over time you can increase the level of difficulty by lowering and elongating your stance and making your strikes pop faster and harder.
Choosing a form to start with is tricky if you haven't done them before. I recommend starting with a basic form from karate or taekwondo. Those forms don't have much variation and won't exercise the whole body, but they still give you something. If you learn multiple forms, you'll probably get more of a complete body workout.
Some of the more advanced forms have you moving in weird ways that are physically challenging. And if you really want a challenge, look at traditional or contemporary Wushu Kung-Fu forms. I find kung-fu forms in general to involve a lot more variation of movement than karate or taekwondo forms do.
You don't need forms, though. Like I mentioned before, you can just take the drills straight from boxing, karate, muay thai, BJJ, MMA, and wrestling. Combine the drills together to make a workout. You can absolutely work yourself out that way. And you can do it in as little as 10 minutes a day in addition to your normal gym workout.
There are tons of videos online for this purpose. Here are some I found just with a quick search of Youtube. I've selected them to cover a broad range of martial arts styles from grappling to pure striking, eastern and western:

https://www.youtube.com/watch?v=EXjP50SOwK4
https://www.youtube.com/watch?v=IRUtpYQ0c6E
https://www.youtube.com/watch?v=H4luaFHs7O4
https://www.youtube.com/watch?v=suvM7sJo-6w
https://www.youtube.com/watch?v=2b3tQIZaUcw
https://www.youtube.com/watch?v=aO3uaGOu2Oo
https://www.youtube.com/watch?v=MpGGMkphci8
https://www.youtube.com/watch?v=NTwPEfMUauw
https://www.youtube.com/watch?v=Ujly7l3-xUM

That's not by any means a complete list. There are thousands of videos just like these, and they all have some things that you might find interesting enough to take and use.
And below are some "forms" videos that I thought you might want to look at. These are arguably some of the most well known forms from karate, traditional and contemporary / northern and southern kung-fu, and taekwondo. I chose them based on my personal experience in these martial arts.
Some are basic, some are advanced. The videos are sometimes grainy, out of focus, or may only cover one viewing angle. And these particular demonstrations aren't necessarily ones that I think are good to learn from. They just showed up on a simple search, that's all, and they at least show the form reasonably well.
The important thing is to get the name of the form and look up other versions online to correct yourself, if you want to learn them. Since they're very popular and widely practiced forms, you should have no problem finding other videos and articles that discuss them:

https://www.youtube.com/watch?v=KOEgRrWZh48
https://www.youtube.com/watch?v=e2da_YijN9U
https://www.youtube.com/watch?v=fict-rt_a1I
https://www.youtube.com/watch?v=5rnar_APMgI
https://www.youtube.com/watch?v=koOaztyceUs
https://www.youtube.com/watch?v=IFKWfAlgGKw
https://www.youtube.com/watch?v=ip4gKICJD6c
https://www.youtube.com/watch?v=TVz-Wkm3pfw
https://www.youtube.com/watch?v=5jJuTkz0psY
https://www.youtube.com/watch?v=FomUPyqf-qY

One final thought about using martial arts as a form of exercise...
A lot of people here will probably cringe at the thought of someone learning to do martial arts movement from video without proper, in-person instruction. They'll point out that without an instructor to correct your movement in person, you're going to learn the wrong movement, and you're going to drill that into your muscle memory. If you were then to go on to learn martial arts for real at a school, your instructor will have to work a lot harder to correct you, because all of the flaws you learned over time have to be un-done. It's much easier undoing flaws before you drill them in to your muscle memory, before it becomes a bad habit.
That is something to think about, if you ever intend to go into martial arts "for real", rather than just learning it as a form of exercise.
This idea applies to any form of exercise as well, by the way. If you learn how to do weightlifting from videos or from a book, rather than getting with a personal trainer who can correct your form in person, there's a good chance you're going to learn it incorrectly, or at least sub-optimally.
In weightlifting, if you have bad form, it can cause serious injuries over time. In martial arts, that's less of a concern, since you're not putting huge loads on your body - with the exception of doing punching bag work, where you can cause injury over time with the wrong form.
So these are things to think about. If you're uncertain after watching videos, it might be time to head to a martial arts school and enroll in some classes for however long, until you feel confident that you've learned the correct movement.
And the biggest thing to keep in mind: If you feel like something is causing pain, stop immediately. Pain is usually your body's way of saying you're doing it wrong, or you're not ready for this movement.
Hope that helps!
Comment: Thanks a ton @Steve Weigand ...the article is brief and helpful indeed.
Answer: Anything that has cardio as part of it should suffice.  This is a one that I have heard a lot about https://www.taebo.com/ there are forms of Cardio kickboxing that I have participated in as well which is basically kicks/punches etc... in a fluid continuous motion to music to get the heartbeat up for the duration of exercising.
Answer: Martial arts are the wrong vehicle for weight lose.
First, muscle weights more than fat so hard martial art training will make you gain weight as you build muscle. Those muscles will be specialised in doing the right thing for the specific art you train in. If you want broad spectrum, you have to cross-train. Second, your body is super lazy and the amount of energy you have to spend to do the same set of moves will diminish over time. This is why variety is important in weight lose exercises. Thirdly, martial arts do nothing about your calorific intake but put more pressure on you to eat more.
100kg for 175cm tells us nothing about your fat percentage or your waste to height ratio. The less said about the aberration that is BMI, the best. Furthermore, nothing is said about what type of body you wish you had: slim free-climber one or body builder one! Clearly, the training will be different.
Comment: Thanks @Sardathrion ....I would like to add something in my Gym workout . I do punch & throw kicks to punching Bags move around like Boxers, jump with spinning kicks which I feel sheds more calories compared to a constant Cardio exercise on a Tread Mill or Elliptical as it makes me much more exhausted. Do you think it is good for calorie loss as it also gives a lot of flexibility .
Comment: If you want cardio, train that. If you want flexibility, train that. If you want calorie burn, train that. If you want to learn a martial art, train that. *They are all separate things.* To be fair, those things all help each other but then again, so does ballet.


Photo editor to automatically detect image face and plant another image on top

Question: I have created a video and exported it as individual photos. I currently have around 200 of them. I am looking for an editing tool that will automatically detect the face in each image and apply an effect to it (put something on top of it). Is this possible? If so how?
Answer: Do you mind doing some (simple) coding? The OpenCV computer vision library includes face detection routines, and there's a Python interface.
And here's a quick howto on doing it with python, including sample code showing someone doing exactly what you want — the image is the input, and then ImageMagick is used to draw a square around the face.
Comment: This is the kind of answers that makes me think that most photographers who hang out in photo.SE came from SO.
Comment: My python bias is showing in my answer, by the way. If you just want to do it with C, tada: http://opencv.willowgarage.com/wiki/FaceDetection
Comment: Wow, this is incredible. thank you. Do you know of any libraries in c# though?
Comment: I don't know much about C#. Can you call C library functions in some way? There's gotta be. That's probably a question for http://stackoverflow.com/
Answer: I don't know one to do this, but using a few different programs and a lil' scripting, you could probably accomplish this with Picasa and GIMP (or maybe even just ImageMagick).
Picasa has facial recognition built in and and stores the facial rectangle in a hidden picasa.ini file in the same folder as the picture.  This file contains a line that looks like:
faces=rect64(328f08a1ae66e711),e5013ddaca3d0567
That number inside the rect64() is a 64-bit hexadecimal number and can be transformed into 4 16 bit bounding corners I believe.
You can take that information and transform it into a into a rectangle that defines the facial area.  Details on how to do that appear to be able to be found here.
You could then script ImageMagick or GIMP into overlaying the previously defined area in the picture with your desired image.
These are obviously not detailed instructions, but I don't think it'd be too difficult to hack together.


How do you analyse components of Index option to help you get more accuracy while trading options?

Question: Suppose, you trade in options, Option index comprises of Many stocks, so how do you analyse those stocks in order to determine the movement of price in options while doing intraday trading?
Answer: Option price movement is related to delta, and the size of and the direction of price movement.  That's a separate issue from predicting price movement in the underlying.
Indexes are comprised of lots of securities.  A small one like the DJIA has only 30 whereas the IWM has approximately 2000.  Regardless of the number,  I think that it's an exercise in futility to try to analyze the component stocks of an index to determine index direction.
However, if you believe in technical analysis or some other predictor, that might be applicable to the price movement of the index.


Find the values of $a$ and $b$ if the limits exist.

Question: Could someone solve this
$$f(x) =
\begin{cases}
x^3+a, & x<0 \\
a\sin\frac{\pi{x}}{3}+b, & 0\leq {x}<2 \\
3, & x=2 \\
\log_2x^{b+1}, & x>2\\
\end{cases}$$
If $\lim_{x\to0}$ and $\lim_{x\to2}$ both exist, find the value of a and b.
Comment: I'm not the downvoter, but the the downvote is likely due to no attempts have been shown. You should include your attempt when you post the question
Comment: MathJax hint:  instead of commas to separate the expression from its range of applicability, use an ampersand (&).  That will space them out nicely and align the ranges
Answer: We have $$\lim_{x\rightarrow 0^-}f(x)=a; \lim_{x\rightarrow 0^+}f(x)=b;$$ $$\lim_{x\rightarrow 2^-}f(x)=b+a\frac{\sqrt{3}}{2}; \lim_{x\rightarrow 2^+}f(x)=b+1$$
Because $\exists \lim_{x\rightarrow 0}f(x)$ and $\exists \lim_{x\rightarrow 2}f(x)$, then
$a=b$ and $b+1=b+a\frac{\sqrt{3}}{2}$ so $a=b=\frac{2\sqrt{3}}{3}$
Comment: @Nigel: *"I did it that way ..."* If so, then you should have included your solution with your question, so that people could simply validate it for you. In general, you should show whatever work you have done, so that answerers have a better idea how to answer you, without wasting time (theirs or yours) explaining things you already know. It can be particularly irksome for an answerer to go through the trouble of solving a problem and formatting an elaborate, instructive answer only to have the asker comment "Yeah, I already did that." Be a *considerate* asker. Cheers! :)


Do I need Customs clearance to fly an N-registered aircraft from Italy to Switzerland?

Question: I need to fly from Italy to Switzerland in my aircraft with N markings.
I've been told I need a clearance from a customs office within an airport prior to crossing the border. Is this true?
Answer: It's true. You need to take off from a authorised Airport with customs in Italy and land at an airport with customs in Switzerland as your first stop.
Here is all information you need including a list of airports with customs.
https://www.ezv.admin.ch/ezv/en/home/information-private/waren-anmelden/einfuhr-in-die-schweiz/warenanmeldung/grenzueberschreitende-fluege.html
Answer: It's not to do with the N-markings... ANY aircraft that wants to fly between Italy and Switzerland needs to fly between 'Customs airfields'. Note - you don't need permission from Customs, just to leave and enter via a Customs airfield, reporting to Customs at those airfields.


Eclipse junit runner that isolates output for individual tests which may be viewed in console individually?

Question: Imagine a test suite with a dozen tests. Each might print somet stuff to System.out via a logger etc. The wish or problem is that it is not possible to have the console only show the output for the selected test. The console shows everything. Is tehre a plugin or way to achieve my wish ?
Answer: You can have Eclipse run only one test in a suite, by choosing the test on the Run Configurations dialog (the "Test method" field).
By the way, this isn't really a programming question.  You might get more response by posting the question to superuser.com.


Bluetooth headset gives error connection failed: blueman.bluez.errors.dbusfailederror: protocol not available

Question: Everything works with Nokia BH-604. Jaybird X2 connects and after a few seconds disconnects. Both headsets work with Windows 8.1 in the same computer (dual boot). Using blueman-manager 2.0.4 I get the error in topic. How do I get Jaybird X2 to work with Ubuntu Gnome 16.04?
Comment: same problem here. I have a fresh xubuntu 16.04 installation on my dell latitude e6410 laptop. Trying to connect to JBL Charge3 speaker. The device was paired, but i can connect only to serial port. When Try to connect to audio sink or headset I get Connection Failed: blueman.bluez.errors.DBusFailedError: Protocol not available
Comment: Did you solve it?
Comment: Not yet, unfortunately.
Answer: This solution worked for me: https://zach-adams.com/2014/07/bluetooth-audio-sink-stream-setup-failed/
<code>sudo apt-get install pulseaudio-module-bluetooth
pactl load-module module-bluetooth-discover
</code>
Delete the device from bluetooth devices and pair it again.
Comment: I get "Failure: Module initialization failed"
Answer: I got a new laptop, plugged in the harddisk from the non-working-bluetooth-laptop and everything worked. So this is most likely a hardware version problem, i.e. Jaybird bluetooth does not support older bluetooth hardware.


Factorise a matrix using the factor theorem

Question: Can someone check this please?
 $$
\begin{vmatrix}
x&y&z\\
x^2&y^2&z^2\\
x^3&y^3&z^3\\
\end{vmatrix}$$
$$C_2=C_2-C_1\implies\quad
\begin{vmatrix}
x&y-x&z\\
x^2&y^2-x^2&z^2\\
x^3&y^3-x^3&z^3\\
\end{vmatrix}$$
$$(y-x)
\begin{vmatrix}
x&1&z\\
x^2&y+x&z^2\\
x^3&y^2+xy+x^2&z^3\\
\end{vmatrix}$$
$$(y-x)(z-x)
\begin{vmatrix}
x&1&1\\
x^2&y+x&z+x\\
x^3&y^2+xy+x^2&z^2+xz+x^2\\
\end{vmatrix}$$
$$R_2=R_2-xR_1\implies\quad
(y-x)(z-x)
\begin{vmatrix}
x&1&1\\
0&y&z\\
x^3&y^2+xy+x^2&z^2+xz+x^2\\
\end{vmatrix}$$
$$R_3=R_3-x^2R_1\implies\quad
(y-x)(z-x)
\begin{vmatrix}
x&1&1\\
0&y&z\\
0&y^2+xy&z^2+xz\\
\end{vmatrix}$$
factor $x$$$\implies\quad
x(y-x)(z-x)
\begin{vmatrix}
1&1&1\\
0&y&z\\
0&y^2+xy&z^2+xz\\
\end{vmatrix}$$
$$\implies\quad x(y-x)(z-x)(yz^2-zy^2)$$
$$\implies\quad xyz(y-x)(z-x)(z-y)$$
Also I'd like practical tips on using the factor theorem for these types of questions. My understanding is that the determinant is $f(x,y,z)$ so if we hold $y$ and $z$ constant we could apply it somehow to $f(x)$ alone. I'm not that great spotting difference of squares etc and want a more fail safe alternative. Thanks in advance.
Answer: What you did is correct. But there is an easier way. Remember that for polynomial $p(x)$, if $p(a)=0$ then $(x-a)$ is a factor of $p(x)$.
Denote the determinant by $\Delta$. It is obviously a polynomial in $x,\ y$ and $z$. Now, note that:

$x=0\implies \Delta = 0$, so $x$ is a factor of $\Delta$. Same for $y = 0$ and $z=0$.
$x=y\implies \Delta = 0$, so $(x-y)$ is a factor of $\Delta$. Similarly for $y=z$ and $z=x$

Finally note that $\Delta$ is degree $6$ polynomial. So it cannot have more than $6$ linear factors, and we have listed all of them above. Clearly
$$\Delta=Cxyz(x-y)(y-z)(z-x)$$
where $C$ is some constant. Taking some values (eg. $x=1,\ y=2,\ z=3$), we get $C=1$.
Comment: Thank you for your answer. Really liked the elegance of this method. I have a couple of follow up questions but I believe the correct thing to do is to post a new question as per meta.
Answer: you are not factoring the matrix. you are using the properties of the determinants to simplify. for example, you could write your first step as
$$AE = \pmatrix{x & y & z \\ x^2 & y^2 & z^2 \\ x^3 & y^3 & z^3}
\pmatrix{1 & -1 & 0\\0&1&0\\0&0&1} =
\pmatrix{x & y-x & z \\ x^2 & y^2-x^2 & z^2 \\ x^3 & y^3 -x^3& z^3} = B
 $$
the $E$ matrices are called elementary column matrices and their determinants usually is the product of the diagonals. now use the product rule of the determinants $det(AE) = det(A) det(E)$ to conclude that $det(A) = det(B)$ now you start with $B$ and do further reductions.
Comment: Thanks.I never thought of using a matrix and I can see it tidied workings nicely.


What the "Channel" mean in facebook chat application?

Question: Facebook uses publish/subscribe pattern for their chat app. I used Firebug to catch request in facebook site and I saw that every request to receive message from facebook server almost link to an address with pattern : http://[number].[number].chanel.facebook.com. There is about 0->20 channels which mean number in address pattern will range in [0-20].
I don't know why they need to use channel as subdomain ? Does it relate to divide processing chat message to multiple service (server) to increase server performance ? or just a subdomain name ?
What is your opinion ? I'd like to hear your interesting idea on this.
Answer: I believe they use sub-somains because there's a limit on how many connections per domain a browser can keep open.
See How many concurrent AJAX (XmlHttpRequest) requests are allowed in popular browsers?
So, those sub-domains are not "channels".
Answer: These are special servers which handle only chat messages and notifications. Source: Rodrigo Schmidt's lecture (https://www.facebook.com/rodrigo)


Compilers and beyond

Question: I want to go backwards and learn more about how compilers, processors and memory operate on my programs. I am also interested in the physics on which all of this depends. Any good references or books would be appreciated...
Comment: voltage, current, resistance - it's all physics at the bottom.
Answer: For compilers, the ultimate book is the Dragon Book, aka Principles of Compiler Design. It is a bit heavy going at first, but it becomes easier with each pass you make at it. It's a classic and should be read by all serious students of programming/computer science.
Answer: My first suggestion was going to be Code which has been suggested already.  A better, but harder, book on the subject of processors is Computer Organization & Design by Hennessey & Patterson.  You might look for an older edition on Amazon or Half.com.  They'll be a lot cheaper and have basically the same information.
These will both teach you the basics of how a processor works, assembly language, etc.  This will help you understand how your program will be interpreted and thus, what sort of performance bottlenecks might exist based on your design.
Answer: It sounds to me like you want to get a Computer Science degree. :-)
Answer: The simplest introduction , and very well written is Code by Charles Petzold
alt text http://ecx.images-amazon.com/images/I/31t68r9K28L._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA240_SH20_OU01_.jpg
Comment: That's the book I was going to suggest.
Comment: Great book. I wish I had it when I started out. Then again, not having it forced me to learn a lot on my own.
Answer: I don't normally think of physics and compilers at the same time.
This link might get you thinking.
Answer: Write a simple emulator for something like C64. By thinking of how to emulate the CPU, Memory and other Chips you will learn how these simple machines worked. Today's computers pretty much operate in the same manner with a lot more complexity but the basic idea is the same.
Your emulator doesnt have to be super fast - try and get the C64 welcome message up and if you did your code right - you should be able to POKE and write basic programs and have them work :)
<code>10 PRINT "DONT LISTEN TO ME - APPLE //E's RULE"
</code>
20 GOTO 10
Answer: I would suggest learning enough assembler to be able to write a simple Hello World program in assembler.
This will teach you exactly how the CPU works at the register and memory level.
It will also give you a good introduction into how source code is converted to object files and how the linker brings together all these object files together to create a working program.
Comment: Anyone can write a Hello world program. It doesnt mean you actually understand the language it just shows you can copy some text from somewhere and run a compiler.
Comment: And anyone can learn a lot by studying a program as simple as hello world, provided they are prepared to take the time to try to understand the code they are copying. I am not an assembler programmer, but I can read assembler thanks to the one or two simple hello world programs that I have written.
Answer: Pick up any of the Hennessy & Patterson books.
Computer Architecture - A Quantitative Approach or Computer Organization & Design - The Hardware Interface
Answer: Feynman has a nice bit on the Physics of Computation:

which addresses the second part of your question.
Answer: Pick up a book on "Computer Organization" or "Computer Architecture" on Amazon.  This is what we used when I was in college.  It's not too thick, and will give you the basics, from the gate level all of the way up to how memory is organized and programs are written.  If, after this, you want to look deeper into the physics, then you'll want to pick up a book on semiconductor physics.  (But if I were you I'd just start by looking up "logic gate", "diode", and "transistor" on wikipedia!)
Comment: Anyone can read a book - it doesnt prove you understand it. A practical example such as programming something real shows you truely understand...
Answer: If you really want to get into the physics of processors/ IC's, you need to have a solid electromagnetics/circuit analysis background.  It's certainly not easy stuff, and won't really make you a better programmer.  If you're really interested, borrow some books from an EE friend!
An abstraction up from that is the gate level, which programmers can usually grok since it's all about logic.
Answer: I made a similar resolution after reading Steve Yegge's recommendation to learn about compilers. I've been really enjoying Nisan and Schocken's The Elements of Computing Systems: Building a Modern Computer from First Principles which is first a textbook, second, a one-semester course for freshmen or seniors, and third, a website providing the lectures and cross-platform emulation-simulation software: http://www1.idc.ac.il/tecs/ (TECS)
The topics go from NAND (programming digital logic circuits in HDL), up through flip-flops, ALUs and registers, assemblers, parsing and compilers, operating systems, and GUIs. You, the student, implements every one of these topics on the hardware simulator or software emulator provided on the website. To me, it is a celebration of human ingenuity that this range of ideas can be so deeply covered in 3--4 months by undergrads. One of the authors/professors gave a Google Tech Talk on the subject that's worth checking out if you have an hour to spare away from their course.
I can't recommend an equally-compelling resource for the physics of computation, but I can perfunctorily say that my electrical engineering department's first two core EE courses students could take (simultaneously if they chose) were Circuits 1 and Semiconductors 1. The former dealt with voltage, current, inductors, capacitors, op amps, etc.---while the latter dealt with quantum mechanics, crystals, doping, charge carriers, etc., and most directly spoke to the physics of digital processing and storage devices. It's difficult for me to imagine a hands-on simulation environment like TECS for such a topic, though, making it more appropriate for academic than hobbyist/professional study?

Compilers and beyond


Can I still cast spells through my polymorphed familiar?

Question: Is a polymorphed familiar still considered a familiar for purposes of casting touch spells through them?
Comment: Welcome to RPG.SE! This is a *very good question* for being your first on our site. That said, it is a good idea to review the articles in our [help center](http://rpg.stackexchange.com/help) to get a better picture of how our site works. Happy gaming!
Answer: Yes.
While polymorph bans the polymorphed form from casting spells, the wording of the find familiar spell states that familiars do not cast spells--they only deliver them:

Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell.

All familiars, polymorphed or not, are merely conduits for your spells, and cannot cast spells themselves. Because you are not polymorphed, you can still cast a spell and deliver it through your familiar. The animals you can have as a familiar can't cast spells to begin with, anyway.
The CR limit ensures balance
Note that all of the creatures you can have as a familiar have CR0, except for the poisonous snake at CR1/8. This means that the number of creatures you can polymorph your familiar into is quite limited.
An explanation in the fiction
Your familiar is merely a spirit that takes on a "familiar form":

You gain the service of a familiar, a spirit that takes an animal form you choose...

Moreover, recasting the find familiar spell allows you to change its form:

If you cast this spell while you already have a familiar, you instead cause it to adopt a new form.

This suggests that the physical form of a familiar, which polymorph targets, is not as important as its connection to its master--after all, it is merely a spirit that can take on many mutable forms.
Comment: But his point is correct.  Familiars can't cast spells either, so changing its form to one that also can't cast spells doesn't affect this power.  If the polymorphed familiar still has a connection to the spellcaster (e.g. telepathy, usage of its senses, etc.), then the connection allowing you to cast touch spells through it would also be maintained.
Comment: this answer completely ignores all of the effects of polymorph.  recasting "find familiar" and casting polymorph on said familiar are two completely different effects
Comment: I feel like the best way to answer the question is to answer: Are polymorphed familures still familures? Just because casting the spell over can change it's shape doesn't mean it's the same mechanic as polymorph
Comment: Honestly, that part of the explanation is just to give some basis in the fictional reality. As far as rules go, the fact that familiars only deliver spells and don't cast them is all that matters.
Comment: @Dforck42 Do you wish to ask the question "can a familiar summoned by Find Familiar be polymorphed" as it's own question?  (While I suspect the answer is "yes" it might be worth asking.
Answer: No. Polymorphed creatures can't cast spells
The effects of Polymorph over the target creature's new capabilities include the following (I have added emphasis to the relevant parts of the text):

The creature is limited in the actions it can perform by the nature of its new form, and it can't speak, cast Spells, or take any other action that requires hands or Speech.
The target's gear melds into the new form. The creature can't activate, use, wield, or otherwise benefit from any of its Equipment.

The familiar's ability to deliver one of your spells reads as follows:

Finally, when you Cast a Spell with a range of touch, your familiar can deliver the spell as if it had cast the spell.

A polymorphed creature cannot cast spells, and the ability to deliver a touch spell reads that the familiar is treated as the one casting the spell. Thus, it's not possible.
Comment: The quoted text reads differently to me; it seems to explicitly point out that the familiar doesn't actually cast a spell, but merely delivers it.  If you do interpret it as stating that a familiar actually performs the casting, then do you also use the familiar's caster level (presumably zero) for the purpose of determining spell effects?
Comment: "When **you** cast a spell ... can deliver the spell **as if** it..." indicates quite clearly that it is the character and not their familiar which is doing the spell casting.


Can any type of wave produce an interference pattern from two sources?

Question: Can any type of wave produce an interference pattern similar to the one in a double slit experiment? So for example, could a radio wave create an interference pattern through the airwaves?
Comment: If the wave consists of a single frequency, and if the slits are small enough to allow for this effect to be noticeable, then yes.
Comment: If they are linear waves, then yes.
Comment: radio wise, there is "multipath fading". It's the young double slit where your radio is the screen, and there's more than one path from the transmitter to the radio.
Answer: The only requirement for wave interference is the principle of superposition:
$$ W(x,t) = W_1(x,t) + W_2(x,t) $$
That is, the total wave amplitude is simply the sum of the amplitudes of the other interfering waves.  This condition, along with the condition that the two sources start in phase, are the only requirements needed to describe an interference pattern such as from a double-slit experiment.
Radio waves obey they law of superposition, and so you could perform a double-slit experiment with them.
Comment: Do the sources have to start in phase for an interference pattern to occur? Wouldn't a phase difference between the two sources just shift the interference pattern?
Comment: You are correct: phase differences at the slits (ie source) would produce a skewed interference pattern. Most double slit experiments are designed to eliminate phase differences, since it produces the simplest pattern.
Comment: Monopolar pulses do not exhibit interference in the normal sense.
Comment: A clarification here is that you still need the source to be coherent and **monochromatic**--only one frequency/wavelength. Sound waves can interfere as well. If you have a pair of stereo speakers and play a pure sine tone over them, they will produce an interference pattern (you have to plug one ear to notice). **However**, you will rarely notice this playing music because music is a mix of many different frequencies, and so at any one point in space only a handful of frequencies will cancel out.
Answer: The only necessary condition for interference is that the sources must be coherent (constant phase difference and same wavelength). It is impossible for two independent sources to be perfectly coherent as there will always be random variations in the emission of the photons. Hence it is impossible to produce a sustained interference pattern with two sources.
Answer: Yes any two wave can interfere having same nature like we can  do double slit experiment through the sound wave, for two wave to show interference pattern, phase difference should be constant what I am saying is this.)
Consider say two electromagnetic wave, whose phase difference changes with time.
$$E_1=E_0sin(wt_1-kx)$$,and $$E_2=2E_0sin(wt_2-kx)$$,
And for phase difference.
$(wt_1-kx) - (wt_2-kx) =H$ (where H is phase difference).
it is very difficult to know how they wave interfere at that particular instant.beacuse of their phase changes with time.  So conclusion is
two similar wave (wave have same kind of nature)  can interfere to produce resulting wave, where $A$ will be the resultant amplitude, two sources should be coherent.


What makes a led blow up?

Question: If I connect a LED to a 1.5V battery without a resistor and it blows up, is that because of the voltage or the amperage? I think amperage, but I'm a beginner at this.
Comment: If you fire a gun and it damages something, was it because of the bullet or because of pressure on the trigger?
Comment: LED voltage and battery voltage must match closely.. A good example is 3.0V Lithium and 3V White LED.   A bad example is 9V battery on a 2V Red LED.  When they do not match a current limiting R in series is needed following Ohm's Law.
Comment: The IV curve gets quite steep in the end and the current delivered by a fresh battery is impressive. Add resistance if you have no other current limiting.
Answer: It's because of the power.

Power can be calculated by \$ P = VI \$ (volts x amps) and the answer is in watts.
The power will be dissipated as heat.
Heat will increase temperature until equilibrium is reached (heat lost to surroundings = power input) or the device fails.

A typical small LED can take about 50 mA for a while and a red LED will have a forward voltage drop of about 1.8 V. We can calculate the power as \$ P = VI = 1.8 \times 50m = 90~\mathrm mW \$.
LEDs normally use a series resistor to limit the current to a safe value of 5 - 20 mA for this reason.

An LED is unlikely to "blow up" (whatever that means) at 1.5 V. I suspect that the actual voltage was higher which it could be for a fresh alkaline battery.
Comment: Infra-red LEDs can be lower than 1.5V.
Comment: Still, I'm a little confused about 1.5V. I can wire up a RED LED to my bench supply and set it to 1.5V and I don't think the LED will blow up. And I think the reverse voltage zenering is higher than 1.5V, as well. (And yes, I'm still on the late shift!)
Comment: Yes, I spotted that but failed to address it. See the update.
Comment: hehe. okay. Well, I've measured the brand new AA alkalines often and I almost never see more than 1.59V or so. Maybe European ones are better? ;)
Answer: The relationship between voltage and current is not always clear at first. I like using water analogies for basic examples. Let's say you have a open 55 gallon drum of water sitting in your driveway with a valve on the bottom and you are really thirsty and want a drink. The volume of water represents the current and the pressure of the water represents the voltage. If you open the valve slightly the water will trickle out because even though there is a lot of water above it (current) the pressure (voltage) is low and the valve being barely open restricts the flow of water (resistor). This flow rate is slow enough where you can easily wrap your lips around the valve and drink comfortably. If you were to now cover this barrel with a lid and connect it to your air compressor you will see the water start to spray out of the valve at a higher rate which would make it difficult for you to drink. Say the lid is now stuck and you can't change the pressure (voltage), so your other option is to reduce the flow to a comfortable level by closing the valve (increase resistance). If you were to place a pressure gauge at the bottom of the tank and another on the output of the valve you would see a large difference when the valve is closed and a small difference when the valve is open, this is the same as a large voltage difference when resistor is infinite and zero voltage when the resistor is 0ohms. (Note: An open resistor is like a valve connected to a closed pipe, you can open the valve all the way and water will not flow just like you need a something connected to the other end of a resistor or current will not flow.)
Taking the above analogy back to an electric circuit, think of the barrel of water as a 12V car battery you want to use to run your LED. A typical car battery can provide 500A of current but our LED only needs 20mA so how do you connect a tiny LED to a current source which has 25,000 times more current than we need without vaporizing it? If you use a resistor the LED will be supplied with the proper amount of current and run indefinitely.  If you were to decrease the resistance (open the valve) or increase the voltage (attach the air compressor) the current would increase to a point where the LED would burn out or explode.
Comment: The *volume* of the water is analogous to the current? How does that analogy work? In electronic circuits, current is voltage divided by resistance; it seems like in order for your analogy to be sound, the water volume would have to be proportional to the pressure divided by the resistance of the valve.

What makes a led blow up?


Use grep to find strings at the beginning of a line or after a delimiter in Git Bash for Windows

Question: I have such file:
blue|1|red|2
green|3|blue|4
darkblue|0|yellow|3

I want to use grep to find anything containg blue| at the beginning of line or |blue| anywhere, but not any darkblue| or |darkblue| or |blueberry|
I tried to use grep [^|\|]blue\| but Git Bash gives me error:
$ grep [^|\|]blue\| *.*
grep: Unmatched [ or [^
sh.exe": |]blue|: command not found

What did I do wrong? What's the proper way to do it?
Answer: Here's a quick & dirty one:
grep -E '(^|\|)blue\|' *

Matches start of line or |, followed by blue|.  The important note is that you need extended regular expressions (via egrep or the -E flag) to use the | (or) construct.
Answer: Also, note the single quotes around the regular expression.
So, in answer to the OP's "What did I do wrong?",

You forgot to put the regexp in single quotes;
You chose the wrong type of brackets to enclose the alternate expressions; and finally
You forgot to use egrep or the -E flag

It's always easier to see other people's errors; I wish I was a quick to spot my own :-|


Adding CSS styles

Question: I'm using the Mimemail module with the Simplenews module to theme an email newsletter, but it's not the least bit clear to me where I can store my styles so mimemail can then add them as inline styles to the various HTML tags. From my research I understand you can create a mail.css file where styles can be added or altered but that doesn't seem to be working for me. Am I missing something here?
Answer: I suggest you don't rely on stylesheets but rather create the inline code by hand and uncheck the option: Add stylesheets. If you find this difficult install emogrifier module (not sure but you might need to install htmlmail as well) that converts the stylesheet code to inline code.
I did myself an inline coding.
You might encounter an issue with weird characters breaking your lines in the email body, I am curious if this happens to you too, if so let me know. I think I have the fix for that too.
Answer: The mail.css file should live in the root of your current theme. In fact if you're using an external stylesheet then you need to do this to avoid a WSOD as you may hit this bug.
Comment: gmail ignores the mail.css file even if included. So emogrifier might be a better way to go, unless you include styles online.

Adding CSS styles


Purchase of out of stock items

Question: Title is self explanatory.
Recently I have changed all items of a certain brand as out of stock and the very next day a person purchased two product from this brand. My question is what could have caused this issue?
It is important to notice that

all items of this brand have 0 qty
all of them have stock vause as out of stock
I cannot see items from this brand on front end neither when browsing through categories nor when using search

Could a possible reason this could have happend be that a person had these items in their cart before I marked them as out of stock, or could he has purchased them via google cached page?
This has happened in the past and past research didn't give me much, so I created this question. Could not find any questions that would be similar too.
Answer: Magento will not allow you to change the Qty for Item's Status to Become Out of Stock option to go bellow 0.
For more detail Just Check This link.

Purchase of out of stock items


Is It Possible To Run Two Graphics Cards For Different Applications Simultaneously (NOT SLI)

Question: I am building a workstation PC for Autodesk and Adobe CC work. Maybe a little bit of gaming on the side but it is by no means a priority. Is it possible to run separate drivers for each card, at the same time? So for example a Geforce card might be driving all the displays and performing any gaming related graphics but a compute card like a Quadro or Tesla could be crunching numbers on a 3D or video rendering application at the same time.
Comment: It's certainly possible, but I don't know whether your specific apps support that.
Answer: The only thing of this kind that I know of is running two GPU's using vtd technology, so far as home/desktop computing goes.
For vtd you'd need a vtd compatible motherboard (a lot of the Asrock gaming ones have vtd), a vtd compatible CPU (check tech specs on Intel/AMD website) and a vtd compatible graphics card.
You can then run two different operating systems with the built-in graphics on the CPU running the host system's desktop and the client system's desktop has the graphics card "passed through" to it using vtd.
For example, you could have Windows running as a virtual machine inside Linux. Linux would be using the CPU's on-chip graphics and Windows would be using the more powerful graphics on the card, perhaps for playing games.
Comment: WIndows 10 Pro includes Hyper-V: With that you can run 1 card on the host Windows install and assign the other dedicated to a guest Windows system. Please bear in mind that VTD also requires a compatible CPU, motherboard chipset, Bios that allows to enable it and a compatible graphics card. Nearly all workstation grade business computers have it as standard. Quadro cards can all do it. Geforces sometimes can't do it. If you build your own system you have to check very carefully that everything is compatible.
Answer: I have some experience in mixing video-cards...
In general this isn't going to work out well.
(The suggestion made by bitofagoob in the other answer is a better solution in my opinion.)
For starters combining a Geforce and a Quadro (or even 2 different models Geforce or Quadro) isn't the best idea. The cards are very similar, enough so that also the drivers have a great deal of overlap.
This leads to stability issues as it is quite possible a Geforce driver part tries to control the Quadro and vice-versa.
If you really want to try this always be sure to install the newest driver LAST. And be prepared to uninstall all drivers and redo everything whenever a driver-update (either from Nvidia or Windows 10 decides to give you an upgrade) messes things up again.
It is much better to use 2 identical (and thus a single driver) cards to prevent the driver issues.
For normal displaying of graphics windows/screens a regular Windows application, like Adobe, Autodesk, etc. you can put each application on it's own screen/card and it will almost exclusively use the graphics-resources of that card.
However you need to consider is how your software is going to deal with GPU acceleration: In nearly all applications I have ever seen the software that can make use of GPU acceleration for the heavy duty calculations just grabs whatever card is first, regardless if that card might be doing something else. (And usually the 2nd card doesn't get used at all.)
Additionally gaming on 1 card and running something else on the other has other additional complications:

Most games have a tendency to claim and lock display-resources like they are the only kid in the playground with very little regard for any other software that is trying to work in the background. E.g. in Windows many games/display-related resources (DirectX) are single-program usage only so the game would lock out the other application.
Games require massive CPU power. So, even if you have a very beefy workstation, chances are that there won't be enough CPU power around to satisfy the demands of the other application simultaneously.
Comment: This is interesting. OK, so what if I used 2 identical Quadros, say, Quadro 5000's, with identical drivers. Let's also say I'm only using one large monitor/display. Could I plug the monitor into one Quadro, using that to drive display and applications, WHILE utilizing the additional card (which I remind you no monitor would be plugged into) just for GPU acceleration where needed. I don't think Autodesk 3DS Max could take advantage of that additional card, but I'm pretty sure Adobe After Effects and Premiere Pro could. Am I wrong?
Comment: @MatthewJendrasiak Maybe. That appears to be your best bet. It totally depends on how the application that needs the GPU selects which GPU to use. Some applications have an  option to explicitly set that. Others just have internal logic that may or may not do what you want. I think no one is able to predict what will happen. Trail and error seems needed. If you get it to work please post a followup (you can self-answer your own question) . I'm really interested in the results.


How to improve problem solving skills while unemployed?

Question: I graduated from the university where I learned mathematics, computer science, statistics and physics. It was really nice to solve problems and optimize things. How can I improve my problem solving skills while I'm unemployed? I mean, is there some kind of website where is problems with various difficulty levels and one can build portfolio by solving those, and maybe some discussion forum about how to improve existence solutions?
Comment: Afraid this isn't really a workplace question, and it's also rather broad and open-ended, so not a great fit for this site.
Comment: Is there a specific reason why you want to improve your problem solving skills this way? The "normal" way would be after university to land a job (which sounds quite doable with your education) and improve your skills there. The bonus is that you get paid to do this...
Answer: Not enough rep to leave a comment, but off the top of my head:

Kaggle (quite difficult, real world problems; IMHO best way to build genuine skill)
Any number of programming puzzle question sites, like Hackerrank; these are geared more towards interview style questions
Code Review Stack Exchange is quite good for the discussion element of your question; you can get good, in depth feedback on relatively small bits of code


How do you imagine momentum?

Question: If you want to explain it to a layman (who belongs to the science stream ofc!!) how do you explain it? Also, what is momentum transfer when it comes to fluid mechanics?
Comment: "I like to picture Momentum as a mischievious badger," Cal Naughton Jr.
Comment: Imagine a very large rugby player running into you at a low speed - would likely knock you over. Imagine a child running into you at double the speed, would probably bounce off. The combination of weight *and* speed are what make up momentum.
Comment: Ever played snooker, or pool?
Answer: @JonathonRSwift provided a good analogy for momentum using a rugby player or a child running at and into you. The rugby player would likely bowl you over while a child even moving at twice the speed would likely bounce off.
Another example would be a child hitting your hand with a (blow molded/hollow) plastic hammer compared to that of a real hammer being swung with the same velocity.
A simple answer for the momentum transfer of moving fluids could be that of incorporating an waterwheel at the surface of a river to pump water.

Where water is held back by a dam, a Pelton wheel (below) may turn a generator for electricity, also imagine Windmills for grinding grain.
Now imagine reversing the application and you have an outboard engine propelling a boat on the water, a submarine under the waves, or an airplane / jet airliner traveling high overhead.
Addendum: Thank you @Trioxidane for making the point about a Pelton wheel. The scoops are specifically designed to redirect the impacting water "backwards" as much as possible to maximize energy extraction from the moving fluid.
Comment: Good answer. Only suggestion for improving the answer is that a Pelton wheel is a specific type of waterwheel. It has special scoops to project incoming water back, maximising the energy transfer. The one in the picture is a normal waterwheel. Despite that, the idea stays the same.
Answer: The mass has a fundamental property and that is like a battery that can be filled with the charge and become a container of energy, mass by virtue of its inertia can accept the work of a force F moving it and store that work by accelerating and becoming a container of energy.
Say a ball with mass m is moving horizontally in space with a velocity v. what do we mean by recognizing its momentum $ \ P=mv$.
We mean this ball in motion has energy and can deliver work. How much work? Let's say we try to stop this ball by hitting a spring.
It will gradually slow down losing its momentum till it loses all its velocity.
If we add up the amount of decreasing momentum over the span of v going to zero (calculating the are of the triangle in the diagram) or integrating with respect to v we get $$E =1/2 mv^2$$
Meanwhile, all the energy of the ball has been transferred to the spring.
The same applies if the ball is a droplet of water.
Answer: Momentum is a way we can measure mass that is in motion. Any object that is moving has momentum.
The momentum $p$ of an object is equal to the mass $m$ times the velocity $v$.
$$\vec{p} = m \cdot \vec{v}$$
(As a consequence of Newton's laws,) Momentum is directly proportional to the force required to stop a moving object (or in general change its velocity).

Momentum transfer in a fluid is the study of :

the motion of fluids (how do particles interact with each other) and
the forces that produce these motions. (and also what are the forces are produced from those motions)

How do you imagine momentum?


Dust caps for idler pulley bearing?

Question: Recently, I bought a brand new idler pulley for serpentine belt system. When I opened the package, it included the idler and its bolt (picture 3) + a plastic dust cap (picture 2) + a piece of cardboard (picture 1) which I'm not sure what should I do with it!
Is the cardboard thing also a kind of dust cap? Should I install it on the back of the pulley? Guide me please!
I have seen plastic dust caps before but I have some concern regarding the use of them. The plastic cap can prevent dust and water from entering the bearing but I think it can make it harder for the bearing to dissipate heat because it covers the whole surface area. Correct me if I'm wrong and tell me whether you think the dust cap should be installed or not.
Comment: Did any instructions come with it? What does your old one have?  Is there a reason you think they would send you a dust cap if it wasn't for use? Where did your concern re heat dissipation come from - have you had a heat related failure in the past?
Comment: @Rory Alsop - No instructions inside the package. I haven't had any heat related issue in the past because my previous bearing haven't had any dust caps. It is just what I think about it and as I said, I may be wrong. This is the first time I buy a bearing with caps and I need to know more about them before using them.
Comment: In general, the folks manufacturing these know about them. If you haven't had an issue, you shouldn't have a reason to try and second guess them.
Answer: The "cardboard thing" is just there to keep the bolt in place while in packaging. Discard it as it's not needed. Leave the cap off during installation, then place after everything's together. It's basically a dust cap. It isn't truly needed, but will help with longevity.
Comment: @Paulster2 - Do you think the plastic dust cap may come off due to engine or chassis vibrations? What will happen if it suddenly comes off during driving?

Dust caps for idler pulley bearing?


Vector under OSMbuildings

Question: I would like to display a circle object under the OSMbuildings layer with OSMBuildings
. I was trying to change zIndex, bringToBack(), bringToFront() but it doesn't work. I don't use my own GeoJSON data to create 3d buildings. Any help?
Answer: I tested a few things in the "Classic 2.5D" version of OSMBuildings which integrates with Leaflet.
I was able to achieve what you wanted by starting/loading OSMBuildings quite late. If you want to add circles late or during runtime, you will need to have a FeatureGroup with a dummy circle before calling new OSMBuildings(map).load(), or else they end up on top of everything. The map code looks like this:
var map = new L.Map('map').setView([52.51860, 13.37610], 17);
new L.TileLayer('http://{s}.tiles.mapbox.com/v3/osmbuildings.kbpalbpk/{z}/{x}/{y}.png',
  { attribution: 'Map tiles © MapBox', maxZoom: 17 }).addTo(map);

// group where all markers go into
var circleGroup = L.featureGroup();
map.addLayer(circleGroup);

// circle with no radius & transparent color
var dummycircle = L.circle([52.52020, 13.37570], 0, {
    color: "rgba(0,0,0,0)",
    fillColor: "rgba(0,0,0,0)"
});
circleGroup.addLayer(dummycircle);

new OSMBuildings(map).load();

// add another circle that is visible
var circle1 = L.circle([52.51860, 13.37610], 120, {
    color: "#f00",
    fillColor: "#f00"
});
circleGroup.addLayer(circle1);

Demo: http://jsfiddle.net/chk1/w513wsej/ (if you don't see buildings it may be because OSMuildings does not support HTTPS)
Answer: I've also found this solution after a few days by accident. I've just put a second GeoJSON and L.grid() object before new OSMBuildings(map).load(). It's not elegant solution but it works, thank you for your answer.

Vector under OSMbuildings


Set theoretic issue of localization of abelian categories

Question: For a small abelian category in which every object is also a set, consider its localization with respect to a Serre subcategory (thus a quotient category), is it true that under this localization functor $T$, the image of an object is still a set? I wonder if it is always possible to turn this functor $T$ into an endofunctor $F$ such that its image is equivalent to the localized category, as it is considered in triangulated categories where a localization functor is defined as an endofunctor together with a natural transformation satisfying certain properties. In this sense, the first question seems to be resolved naturally.
Comment: It sounds to me like the assumption that "every object is also a set" is misguided. What would be an example of a small abelian category in which *not* every object is a set? The very notion of "small" presupposes set theory, and so the objects of a small category are automatically sets. If you are considering a set theory with urelements then we can get rid of them by moving to an isomorphic category.
Comment: Let us suppose we are working in Zermelo-Fraenkel set theory without urelements. Then *everything is a set*. I do not even understand why you worry about the set-theoretic nature of the objects. Why do you even care whether the objects are sets, bananas or coconuts?
Comment: Do you mean rather that every object of the category _has an underlying set_?
Comment: Is it possible to have an (essentially) small category in which each object is not a set?
Comment: My problem focuses on the localized category, and I wonder when applied the localization functor $T$ the image $T(M)$ of an object $M$ (which is a set) remains a set or not. In the category of finitely generated abelian groups, the localization with respect to the Serre subcategory generated by $\mathbb{Z}/(2)$ say corresponds to the functor given by tensoring with $\mathbb{Z}_{(2)}$. In particular, the image of every abelian group is still a set, the elements are given by equivalence classes of fractions. So I wonder if it is true in general that $T(M)$ is a set for arbitrary localization.
Comment: I think yes. It is true in the case when the abelian category is a module category over a nice ring localized with respect to nice Serre subcategories as I provided.
Answer: Perhaps @user81489 means the following.  Suppose given a concretizable category (note: every small category $\mathcal C$ is concretizable, by the functor $\prod_{C\in \mathcal C} \hom(C,-)$; see also this post on SBS.).  Is its localization with respect to a Serre subcategory also concretizable?
The localization of small category with respect to some subcategory is necessarily small, so in that case the answer is "yes".  On the other hand, I believe that one can modify Freyd's theorem that the homotopy category of topological spaces is not concretizable to the abelian setting to produce a counterexample when smallness is dropped.
Comment: Yes.  A morphism in $\mathcal C[\mathcal W^{-1}]$ is an equivalence class of zig-zag paths in $\mathcal C$ whose "zag" components are in $\mathcal W$.  If $\mathcal C$ is small, there are only a set of such zig-zags, and hence only a set of equivalence classes.
Comment: Yours is a better phrased question. Also thanks for providing the post. As you mentioned, why is the localized subcategory necessarily small? Is it simply because the way of a morphism chosen is depended on a set of objects?


My newly repotted majesty palm is loose. Should I add more mix?

Question: I blended the potting soil with 50/50 sphagnum peat moss/moisture retaining potting soil for my Majesty palm.
It feels kinda light and the palm is a little loose in the pot.
Should I add more potting soil or should I just leave it how it is?
Comment: Is there something you would like me to add to my answer?
Answer: Just using the moisture control mix would have been better. Here is the ingredient information:

Our potting soils generally contain peat moss (the major component that is harvested from natural peat bogs), compost (the compost may contain animal manures, composted leaves, grass clippings, and/or composted bark), and perlite (white volcanic rocks used for drainage and soil texture). Some contain Osmocote fertilizer that look like small clear fluid-filled balls.
The Miracle-Gro Moisture Control Potting Mix also contains composted hulls of coconuts to help absorb more water than regular potting soil. This is the Aqua Coir (pronounced "core") component of the soil.

Adding sphagnum peat moss 1/1 was unnecessary, and if you just repotted recently, I'd recommend doing it over again with just the mix. Light mix is good for a palm, but it won't thrive in 1/2 sphagnum peat without a lot of fertilizer frequently, as it will tend to run right through.


Dell touchpad not working

Question: I am using ubuntu 16.04 on my laptop dell inspiron 5577 gaming.My touchpad has not been working since i installed ubuntu though the touchpad works fine in the pre installed windows 10.I have tried the solution from Touchpad under 16.04 not working and it doesn't even detect my touchpad,i have tried many solutions i don't know what to do now.It even has few other problems like the battery indicator is not showing and the laptop doesn't even shutdown properly.Please help.
Answer: I've had this exact laptop with the exact same problem(among others) with ubuntu 16.04.
I'm not entirely sure if this is what fixed it but all I did after countless non working solutions offered by others on the internet was:

Upgrade the kernel to the very latest out at the time. I used UKUU to make it easy.
Rebooted(it automatically selects the newer kernel at boot)

and voila! My touchpad was working again.
Also, check to make sure in the Hardware Drivers section if you have any proprietary drivers that need to be installed.
That generally solves a few issues.

Dell touchpad not working


Is it safe to ride with one missing chainring bolt?

Question: I have a double chainring on my road bike but one of my chainring bolts has broken so I'm left with only 4 out of the 5 I'm supposed to have. Is it safe to ride? (just until replacements arrive)
Comment: (And I'd bet that there are folks out there who've been riding for years with two missing bolts.)
Comment: If your cranks don't work you're walking, but any bike shop should have the bolts.  I limped 4 miles back to a bikeshop successfully with 2 missing out of a 5-spider but I wouldn't have ridden it out the next day if the shop had been closed.  (I additionally had to ride several miles over cobblestones to reach decent tarmac and was afraid that that would shake more stuff loose and my command of the local language was just not that good.)
Comment: My big question would be why did the bolt break and does whatever caused it to break mean that the others are in some way weakened.
Answer: As long as you don't take your bike on a long strenuous ride or torque the snot out of it, you should be OK. Make sure the remaining 4 are properly tightened. Normal commuting should be fine.


How is the dipole moment defined in Gaussian?

Question: I wonder if the origin of the permanent dipole moment calculated by Gaussian (16) is always the center of mass (0,0,0 if "Nosymm is used)? For the neutral molecule it does not matter, but I am interested in the case when the molecule is not neutral.
Answer: If my memory serves correctly (this CCL post agrees), the origin used for computing the dipole is the center of nuclear charge:
$$R=\frac{\sum_i Z_ir_i}{\sum_i Z_i}$$
As you noted, the origin doesn't matter if the molecule is neutral and more generally the lowest order non-vanishing multipole will be independent of the origin while any higher order multipole will have some origin dependent terms, see this Physics SE post.
Comment: +1. Wow, did you know that Physics SE post from earlier? I'll briefly point out that this question was also asked on the CFOUR forum and John Stanton's answer was that in CFOUR the origin is the center of mass rather than the center of charge. It's interesting that Gaussian and CFOUR have made a different choice here :)
Comment: Thanks for your response! Well, I also saw that CCL post, but for some reasons I am sure you (and the author of the CCL post) are right. I will try to clarify the issue as much as possible by sending a query to Gaussian and will report the Gaussian's answer here ...
Comment: Well, according to the answer from Gaussian, Tyberius and the author of the CCL post seem to be right :) because in Gaussian the standard origin of the molecule, i.e., 0,0,0,  is by default the center of nuclear charge (I actually thought that it was the center of mass) and this is also the origin of the dipole moment. But one can change the default with the option Symm=COM, which makes the origin of the molecule to be the center of mass.


Why my bios have no option for usb flashdrive boot

Question: My main board is Asus P5KPL-AM.I want to install window 7 by my Sandisk flash drive.I setup flash drive with "Windows 7 USB DVD Download Tool".i plugged my flash drive and restart and go to bios setting in Boot Device Priority it don't have my flash drive just have only cd,floppy,hdd. what should i do
Comment: try choosing "hdd"
Comment: hdd is my internal hdd it boot window normally not boot from my flash drive
Answer: Exit out of boot priority and check to see what the system is set to recognise in the BIOS first, it is possible to turn off things such as USB all together, I don't know the the way around the BIOS for that computer right off hand, I'll google it real quick if you can't find the settings on your own.
Comment: my USB config
USB Functions [Enabled]
USB 2.0 Controller [Enabled]
Legacy USB Support [Auto]
USB 2.0 Controller Mode [Hispeed]

in Boot menu when i go to Hard Disk Drives i can choose my USB:SanDisk but in Boot Device Priority it don't have my SanDisk in Option.
Comment: Let me guess in boot priority it only shows 3 options correct, just highlight one to change it like normal it should show more options to replace it with.
Comment: yes it should show more options(my usb option) but it not show. i don't know why and how i can fix it.