efficient portfolio with given risk

Question: Is there a formula to derive an efficient portfolio to maximise the return, x'mu, for a given risk, x'S x (where x are the portfolio coefficients, mu is the mean return for each asset and S is the var-cov matrix of the assets) ?
Answer: Yes, this is the simple markowitz optimization.
Denote $\Sigma$ as the variance-covariance matrix of returns and $\bar{R}$ as a vector of expected returns.  The tangency portfolio weights are given by $\omega_{tan}=\frac{\textbf{{1}'}\Sigma^{-1}}{\textbf{{1}'}\Sigma^{-1}\textbf{1}}$.
The minimum-variance portfolio is $\omega_{mv}=\frac{\Sigma^{-1}\bar{R}}{\textbf{{1}'}\Sigma^{-1}\bar{R}}$.
Using the two mutual fund theorem one can span the entire efficient frontier without a risk-free asset by linearly combining this two portfolios. Letting $\alpha \in [-\infty , +\infty]$, the efficient   weights of any frontier portolio can be obtained as:  $\alpha \times (\omega_{tan}) + (1-\alpha) \times (\omega_{MV})$ .
Using the risk-free asset, the mean-variance efficient frontier becomes a straight line starting from the risk-free rate and with slope equal to the sharpe ratio.

efficient portfolio with given risk


How do I get an historic view of the inflation votes?

Question: Specifically, I'm interested in knowing what the state of inflation votes were at an arbitrary historic timestamp.  I can run the ledger backward to figure balances, but I'm not sure how I'd figure out previous votes if someone changes their vote.
Answer: In order to get the historical inflation votes data you need to run a Horizon node with CATCHUP_COMPLETE parameter set to true.
Once a fully synced instance is ready, you will be able to query history_effects table which contains all ledger effects. Inflation destination is set by SET_OPTIONS operation that yields SIGNER_UPDATED effect despite the fact that official documentation mentions Account Home Domain Updated effect. Here is a bug description.
Therefore in your case an SQL statement that retrieves all inflation_dest changes will look like this:
SELECT *
FROM history_effects
WHERE type=12 AND details->>'inflation_dest' IS NOT NULL
ORDER BY history_operation_id, order

Add a filter by date and aggregate results to get inflation_dest for all accounts at a given point in time.
Comment: So if I wanted to know how many votes were cast to wallet GAEXAMPLE as of 2017-11-17 at 00:00 UTC, I would first have to figure out which wallets were voting for GAEXAMPLE on that date, and then run a routine to figure out the balances of all of those voter wallets.  Is that correct?
Comment: Exactly. There is another option, if you don't need a historical data. You can setup a Core node, periodically fetch the up-to-date information and store it somewhere. Query in that case will be much simpler, you don't need to build complex aggregation SQLs.


Distance at bottom of porch railings

Question: Is there a standard distance between steps and bottom of porch step railings? What I am referring to is if you measure the distance from a step to the railing above it. The distance I measured was around 10 inches.
Comment: Each City/Town/County in the US has codes for this. Example quick google: http://www.co.stevens.wa.us/landservices/documents/STAIRWAYSECTION.pdf
Answer: The International Code Council says in the International Building Code that a 4" sphere shall not pass through a "guard" for stairs over 30" above finish floor...except for the triangular space formed by the riser, tread and bottom of the guardrail. In which case, it cannot allow a 6" sphere to pass. (There are other exceptions, but none that pertain to your issue.) See Section 1013.4, Exception 2 of the IBC.
Answer: Without an illustration, I presume you mean the sloped bottom rail that the balusters rest on of the stair hand rail system.
If I remember right, this is pretty much standard everywhere in the US.
This is a copy and paste from the pdf referred to by nobyman. His was handy, it saved time...
R312.3 Guard opening limitations. Required guards shall not have openings from the walking surface to the required
guard height which allow passage of a sphere 4 inches (102 mm)in diameter.
 Exceptions:
 1. The triangular openings at the open side of a stair, formed by the riser, tread and bottom rail of
 a guard, shall not allow passage of a sphere 6 inches (153 mm) in diameter.
 2. Guards on the open sides of stairs shall not have openings which allow passage of a sphere
4 3/8 inches (111 mm) in diameter.
Comment: Evidently it did not save enough time, Lee Sam got there first

Distance at bottom of porch railings


Most effective ways of learning Russian?

Question: I have been studying Russian for almost two years as a full-time student and feel disappointed that I'm not more fluent. It seems like no matter how much Vocab I learn, I still don't understand authentic texts...and I still make lots of mistakes with cases. How do you supercharge your learning to learn Russian more quickly and effectively? Thank you.
Answer: One way to build up vocabulary is extensive reading ( https://en.wikipedia.org/wiki/Extensive_reading ). Note the contrast with "intensive reading".
If you have a desktop computer and use Chrome, you can install the Google Translate extension, and then have instant lookup of words or entire phrases within a webpage, using Google Translate as a kind of substitute for a dictionary. Then you can tackle web pages that are somewhat above your level, but keep moving forward steadily and refrain from the temptation to look up every unknown word. Inferring meanings or just getting the gist is usually enough for learning purposes. Some of the new words you encounter might be instant "keepers", but many others will be "not now", so just catch and release.
Find content that personally interests you. Avoid dutifully plowing through texts that bore you.
For reading purposes, you only need to be able to recognize cases and conjugations, not to be able to produce them yourself. You could compare it to "demonyms" in English (like "New Yorker", "Bostonian", "Dallasite"), which are often unpredictable: do they end in -er, -ian, -ite, or maybe -ese or are they entirely irregular? But you only need to recognize these when you see them, you don't have to memorize the demonyms for every city in the word, including irregular cases like Muscovite and Angeleno. At least not at this stage.
So maybe try extensive reading in your extra time, keeping it entirely separate from your regular school-related learning, and you may find your passive vocabulary grows quickly. And passive vocabulary, once firmly embedded in your brain, tends to stick long-term, as opposed to active vocabulary which is very much "use it regularly or lose it".
Comment: When I was an ESL teacher, my best students (apart from those who had spent substantial time abroad) were those who spent most time playing computer games and watching movies/TV series. Concerning games in Russian, have a look at Metro.
Answer: Two years of college Russian is not that much.
What I did:

Summer intensive in Polish (beginning level , first slavic language I had been exposed to)
Academic year of college Russian
Summer intensive in Russian
Another academic year of college Russian
Another summer intensive in Russian
Then I went there to work for 6 months/year for 2 years

At the end of all that, my Russian was pretty good. Not perfect, but I could follow 3/4 of most movies and media.
Russian is a big lift.
Answer: I worked in Russia for a while and I have a Russian born wife. The thing is not to get too hung up on the grammar. The Russians often get it wrong themselves and in any case emphasise the root rather than the endings. They certainly wouldn't bother to comment if a foreigner declined a noun incorrectly. My wife has been known to ask me occasionally as to the exact ending of a word when she is writing some formal letter.


How do you know if an analog film camera is still working?

Question: So my dad recently gave me his old film camera. I'm eager to use it but I'm scared that if i buy the battery and film, it won't work since it's quite old. I looked it up on the internet and only few reviews and things come up. It's a Canon Autoboy Zoom Super. How do you know if it's still usable? Thanks!
Comment: In your case, since the previous owner was your dad, you can have a pretty good idea if the camera has ever been mishandled or malfunctioned. If not, there's no major reason why it shouldn't still work fine, but see the good answer by @Kahovius below. Shop around for the battery, film and processing. You might be able to pay for everything with less than $25. If the price is an issue, see if your dad will help out with the initial test costs.
Answer: To render this answer more generally useful, I will first give some general tests to perform not specific to your particular model of camera:

If the camera needs a battery, get one and pop it in. For an initial test, it needn't necessarily even be the exact same battery, as long as the voltage is close enough. (Some old cameras were designed to take batteries that are no longer manufactured, so one often has to improvise here.) Is there any corrosion in the battery compartment (bad sign)?
Find out if the shutter fires at all. Pressing the shutter button, do you hear the shutter closing and opening? Looking through the lens (or without lens, if the camera has interchangeable lenses), can you see the shutter close and open? (Selecting a slow shutter speed will help here.)
Try and figure out if the shutter speeds are sensible. A fast shutter speed (e.g. 1/500) should look and sound different from a slow one (e.g. 1/15).
Do all the external controls (shutter speed selector, aperture selector, ISO selector, etc.) seem to work properly?
Opening the back of the camera, is there visible deterioration of the light seals that keep the camera light-tight?
The ultimate test for an analog camera is to put some film through it and have it developed. (You don't necessarily need to get the negatives printed – just developed – to see if the results look sensible. This will be a bit cheaper.) Cameras can fail in so many ways that this really is the only way of knowing for sure whether yours is working properly.

Now, specific to your case, I'm not familiar with the Canon Autoboy, but based on a cursory web search it looks to be a fully automatic camera. This means that some of the above points will have to be modified a bit, since you won't be able for example to select a shutter speed (rather, the camera will figure out the right shutter speed for you). However, you should be able to adapt the above advice. Take the camera outdoors, thereby forcing it to select a faster shutter speed. Press the button and observe what happens. Then take it indoors (thereby forcing a slower shutter speed). Does it look and sound different? To be honest, with a fully automatic, electronic camera it's less likely that the shutter speeds will be off relative to each other, as long as the shutter fires at all.
This comes with a caveat, however. It is possible that your camera won't fire the shutter at all unless some film is loaded. If that is the case, then the above advice is, admittedly, pretty useless unless you're willing to buy a roll of film and just give it a go. Do let us know if this is the case – it would be interesting to know.
Finally, how has the camera been treated and stored? There's no reason in principle why an old camera shouldn't work if it's been properly cared for. I routinely use film cameras 50–60 years old and they perform as good as new. If this camera holds some emotional value for you, and considering that battery+film+development isn't really all that expensive, I'd give it a try!
Comment: If you do try a reel of film, make a plan of the different types of shot you want to test (light levels, flash, focus distance, etc) so you can take a wide range of test shots on one film reel in a short timescale. Also, *make notes of the shots you take*. There is nothing more frustrating than when 10 out of 12 tests shots are OK and the other two are either black or completely burnt out, *and you can't remember what those two failures were supposed to be*. Or for two shots of the same scene, one is good and the other is bad, but you can't remember the camera settings for each one.
Comment: A way to avoid this is to include in the shot a whiteboard with the camera settings written on it. At least you will know the settings that work :)
Answer: Get a battery and a roll of cheap BW film and give the camera a ride...develop it (or have it developed), make a contact sheet and be expectant of the camera surprising you. After that we can continue talking about it...


Montesquieu's political freedom : positive vs negative freedom?

Question: "(Political) Freedom is the right to do whatever the laws permit." This is a famous sentence of Montesquieu. Today we tend to describe philosophies of freedom with "positive freedom" and "negative freedom", I think Montesquieu by this sentence fits well into the category of philosophers who advocated for negative freedom. However, he also says: ' Now a government is like everything else: to
preserve it we must love it.' Does this implies that he also stands for positive freedom, because he asks people to love government? If so, is his theory about freedom self-defeating?
Answer: Negative and positive freedom
Negative freedom is largely, as you suggest, exemption from external interference in the way of coercion, constraint or force. (I could analyse and distinguish these concepts but their intuitive sense is plain enough for purposes here.) If you lock me in a room, tie me up, make dire and realistic threats which you have every intention and ability to carry out unless I comply with your wishes, then you restrict my negative freedom.
Positive freedom centres on internal factors. If, for instance, I have compulsive desires, overwhelming depression, or am neurotically indecisive, I still have negative freedom - I am not subject to external interference - but I lack the autonomy, the self-mastery, to act as a coherent agent.
Negative and positive freedom are not to be equated (as they so often confusedly are) with 'freedom from/ freedom to'. Wherever that distinction comes from it does not capture at all the difference)s) between the two freedoms, negative and positive. Nor does positive freedom involve following the mandates of the 'rational self' as Isaiah Berlin suggests. It just means the absence of a range of internal impediments to coherent action.
Montesquieu

Now a government is like everything else: to
  preserve it we must love it. (Montesquieu, The Spirit of the Laws', IV.5)

Montesquieu is talking specifically of 'republican government', something at least close to democracy. The following extract from Christopher Wolfe elaborates the point about 'love' :

Every government requires obedience to its laws, a minimum
   of order which implies some limitation on "freedom." A monarch or a
   despot can ensure this minimum of order by force; it is less clear that
   a people can coerce itself. If force is needed, the republic is already
   corrupted. The people must voluntarily restrain themselves if the republic is to be preserved. To do this, Montesquieu thinks that they must
   have some sentiment or passion which leads them to do so. This passion
   is virtue, the love of one's fatherland. Without it, the likely result of
   license is anarchy, followed by despotism of some kind. (Christopher Wolfe, 'The Confederate Republic in Montesquieu',  Polity, Vol. 9, No. 4 (Summer, 1977), pp. 427-445 : 431.)

Again :

....as a citizen must be
   "virtuous," love his country to the point of self-renunciation in order to
   avoid the anarchical possibilities inherent in democratic liberty (Wolfe : 435).

Much the same point is made negatively :

The citizens of modern
   republics, however, have been divided in their allegiance, since their love
   of country (their "virtue") is diluted by the pursuance of their individual
   interests, which sometimes conflict with the general good (for example,
   the development of powerful business and labor union monopolies). (Wolfe : 429.)

Civil virtue
It is plain from this that what Montesquieu desiderates is 'virtue' in his citizens - active and enthusiastic support and a willingness at least in major matters to put the general good before individual interests.
Virtue or love of the political system may be essential to self-government but whatever the cogency or persuasiveness of Montesquieu's acclamation of love, it has so far as I can see no connection with positive freedom.
___________________________________________________________________________
Montesquieu, The Spirit of the Laws, 1748 : https://socialsciences.mcmaster.ca/econ/ugcm/3ll3/montesquieu/spiritoflaws.pdf
Christopher Wolfe, 'The Confederate Republic in Montesquieu',  Polity, Vol. 9, No. 4 (Summer, 1977), pp. 427-445.
Isaiah Berlin, Four Essays on Liberty, ISBN 10: 0192810340 / ISBN 13: 9780192810342
Published by Oxford Paperbacks, 1969 (reprinted many times).
Geoffrey Thomas, An Introduction to Political Philosophy, ISBN 10: 0715626442 / ISBN 13: 9780715626443
Published by Gerald Duckworth & Co Ltd, 2000 - see index under 'freedom' for negative/ positive distinction.


Building up a (small) Crowd-testing community

Question: I am planning to build a small community of testers for my mobile application, a sort of crowd-testing group for exploratory/regression testing.
Does anyone have any suggestion on how to find people who would be available to test my latest release on a regular basis? since it's a health/fitness app, testers should be active (walk/run/work-outs ...).
Also, what is the "standard" for rewarding the testers? is it per bug found? is it flat fee?
Comment: There are no 'standards' like this on the internet, especially on a global scale.  You have to try and do what works for you, your app, your audience, your budget, your product, etc.  One thing to think about is what would (from the testers point of view) make this a 'community', not just a bunch of individual testers.  You might like to have a community but why would they?
Comment: A bug found for a solo developer 'joe' might have a $10 reward.  For google it might be $100,000
Comment: Generally once you find what works for you today, you'll need to change it "tomorrow" if your need continues. ("tomorrow" might be next month, years, etc).
Answer: Friends and Family

Ask your family
Ask your family members to each ask a friend
Ask your personal friends
Ask your personal friends to ask a  friend
Ask your work friends for a favor
Comment: Thanks for your answer and comments. While everyone can test by using an app, not everyone can see whether it's a bug or misuse of the software or is comfortable writing a ticket with all the information needed to reproduce the issue. That's why for instance I cannot ask my parents to help or some of my friends, or most of my neighbors.
Comment: Whoa, write a ticket?!  That's NOT what I expect a family member to do.  That's a part that YOU would have to take on.  Asking neighbors and friends is definitely hard.  The only thing I know that is harder is asking strangers to do it for free.
Comment: To be clear, this won't work for everyone, but it is posted as an answer as it will probably be a good approach for some in this situation.  Real world users can determine if they think a bug is a bug.  Domain knowledge might be a barrier though.
Comment: Not really sure how I feel about this - I wouldn't trust someone that loves me to give me honest feedback on a project!
Answer: I'm highly torn whether or not this question is on topic or not. But the community doesn't seem to think so, so I'm not throwing my hammer at it, and I thought I'd throw an answer on it too.
The best crowd to test your app are the people who love your app. You could get people who love you, but they might be more interested in how you feel about what they say than what they actually say. It's hard to get honest feedback from them.
You could also get people who love testing. For iOS apps, there's https://www.reddit.com/r/TestFlight/ and for Android apps, there's https://www.reddit.com/r/AndroidAppTesters/ - I'm sure there are others if you root around enough. And you may have success with this, but the people who are looking to test this particular app are unlikely to be familiar with your product domain.
But what about the people who actually use your app? They might not know testing, but they will know when things don't work the way they're supposed to. And I would never suggest to abandon professional testers entirely, especially if this is a for-profit enterprise. But you can easily reward people who test with a variety of different things.
First, early access and feedback means the things they want are more likely to get attention, which might be very valuable for them or their company. Such mutually beneficial relationships are wonderful (and a primary driver of FOSS applications, in my experience.)
Second, it's amazing what users will do for a badge of recognition. Stack Exchange literally wouldn't exist without it.
And finally, some people just feel good helping out a small business/operation. Everyone loves an underdog. I remember when I was a teenager playing video games there were some people who helped me gather all my materials for a huge project. At the time I kind of thought they were suckers for all the essentially free work they did. As I got older, I realized they were just having a good time and it gave them all a reason to hang out together.


Could cosmic background radiation be used as a means of cataloging parallel universes?

Question: In a situation where you have people traveling between parallel Earths, where they dropped in with little ability to tell which Earth they are on, could checking cosmic background radiation be a sensible way to ascertain if this is a universe they had visited before?
Answer: This is a very clever idea. Kudos to you for coming up with it.
The answer depends on a few things. First, the temperature of the cosmic microwave background is related to the redshift by the formula
$$T(z)=T_0(1+z)$$
where $T_0$ is the temperature we measure today, at redshift $0$. Noterdaeme et al. (2010), incidentally, remark that $T_0=2.725\pm 0.002\text{ K}$.
Cosmology and Particle Astrophysics, by Bergstrom and Goobar, mention that there is a redshift-time relation:
$$t(z)~\frac{2}{3H_0\sqrt{\Omega_M}}\frac{1}{(1+z)^{3/2}}$$
where $H_0$ is the current Hubble constant and $\Omega_M$ is the density of matter in the universe (part of the density parameter). Inverting the relation, we find that
$$z(t)=\left(\frac{2}{3H_0\sqrt{\Omega_M}}\frac{1}{t}\right)^{2/3}-1$$
You can then find the temperature as a function of time, matter density, and the Hubble constant:
$$T(t)=T_0\left(\frac{2}{3H_0\sqrt{\Omega_M}}\frac{1}{t}\right)^{2/3}$$
Let's say that your intrepid travelers always visit each universe at around the same point in time - that is, they aren't bounding around from the Big Bang to the end of the universe and back. Then there's one basically one factor to measure, assuming all universes have the same age:
$$T\propto T_0H_0^{-2/3}\Omega_M^{-1/3}$$
If you can measure this factor, you can probably differentiate one universe from another.
Also, don't limit yourself to the cosmic microwave background! There's a gravitational wave background and a cosmic neutrino background, too. We can use information from the cosmic neutrino background (C$\nu$B), too; the mean velocity of a neutrino in the background is given by (see Safdi et al. (2014))
$$\langle v\rangle=160 \left(\frac{m_{\nu} c^2}{{\rm eV}}\right)^{-1} \ (1+z)\ \ \ {\rm km/s}=160 \left(\frac{m_{\nu} c^2}{{\rm eV}}\right)^{-1}\left(\frac{2}{3H_0\sqrt{\Omega_M}}\frac{1}{t}\right)^{2/3}\ \ \ {\rm km/s}$$
In other words,
$$\langle v\rangle\propto v_0 m_\nu^{-1}H_0^{-2/3}\Omega_M^{-1/3}$$
which is a similar relation.
Comment: @RadovanGarabík Well, yeah. :-) I do think that precision experiments could differentiate between universes where some things were changed by only a tiny bit. The trouble is, changing things by a tiny bit can cause big problems (think of [fine-tuning](https://en.wikipedia.org/wiki/Fine-tuning)).
Comment: Thus you proved the CMB can be used to differentiate between universes that differ significantly in age, expansion rate or mean density. In other words, between universes so different that there would hardly be any trace of Earth in them :-)
Answer: No.  Interesting parallel Earths branched from ours within the last million years or maybe billion years if you want to look at totally alien life.  The background radiation is coming to us from 14 billion years, with just a little modification from very large things in the way.  If the timeline diverges a million years ago, the background radiation will still be from the time before that so be exactly the same.
Answer: After reading your title and question, I remembered an article I read about something along these lines.  Basically, there is a theory that the cosmic background not only provides hints that there was a universe before the big bang that it also shows "bruising" where it has collided with other universes.
Answer: I am afraid that it would not be very practicall unless the situation were very specific.
Note: I use terminology that is original according to Wikipedia, because I find it more logical: the Universe is everything and multiverses are big parts of it (in this case looking like the classical image of the Universe in modern cosmology).
Mean background radiation temperature depends on the age of the multiverse and expansion rate and for this temperature to change significantly, the whole multiverse would have to be so much different that the existence of Earth-like life could be hard to justify.
More precise measurements of the mean temperature and deviations from it require advenced satelites collecting data for a longer time unless you assume a new, very advenced technology. Besides, if the multiverses we visit were globally similar, even such measurements would not show differences - such differences would mean that totally different galaxies exist now far away. If you assume that only the Earth is similar and for example jump technology allows to jump to almost Earth planets that can appear in very different multiverses (it could justify even very different multiverses from the previous paragraph), we could distinguisch them by looking at other planets in the solar system, stars (very easy at night if already the visible constelations are different and the traveller knows them) or other galaxies (with a telescope) unless you declare that all near space is similar enough that it is the background radiation that is easiest to distinguish with available technology.


Windows Server 2012 R2: Client computers not showing in server dashboard

Question: We deployed a new Server 2012 Essentials and joined a client computer to the domain using CCW. This PC initially showed up in the Essentials Dashboard.
Later we joined a few more PCs to the domain and now found that these do not show up in the dashboard. Even the PC that was initially listed does no longer show up there. So something must have gone wrong during the process of configuring the server.
We found no way to get the PCs listed. They are listed in ActiveDirectory, however. A common suggestion we found using Google is to disconnect the computers and rejoin them using CCW. But I'm not happy with that solution so we did not try that. I don't like disconnecting the PCs from the domain because that will probably loose configuration and data already associated in the dashboard. And I'm not sure it will work because there's still the question: Why does the PC initially listed in dashboard no longer show up?
The main problem with this is that computers are no longer available through the RWW website and our customer wants to use this feature for remotely working on the office PCs.
Answer: Just run http://server/Connect from the workstations. Don't take them out of the domain. You shouldn't lose any settings or data.


Why does my 1 1/2 year old cat bite at her paws and run around frantically sometimes during the day

Question: My 1 1/2 year old cat, Penny, has started to run around and bite at her back paws a little while ago. I don't know if she is in pain and I've started to worry a bit. I have noticed that before and after she runs around & bites her back paws, her back kind of twitches and she acts normal again. Does anyone have a slight clue what might be wrong?
Comment: Take her to a vet. One possibility that comes to mind is that she is having seizures. Or perhaps there's a circulation problem in her back legs.
Comment: When you say her back kind of twitches, what do you mean, is it your back side just before he/she runs off? like this https://www.youtube.com/watch?v=L7shgb4Jcyk

or is it more like this https://www.youtube.com/watch?v=-3mjd5vXsTY

the first is instinct for attacking, the second is something is irritating it's back.
Answer: Your cat might possibly have fleas. When this happens with my cat, she will twitch her fur where a flea bites her and then tend to jump and run to avoid carpet locations where (I suspect) fleas have jumped on her in the past. The chewing of paws might be an attempt to chew a flea she has found.


What is the best 3D modeling software for a beginner on a 3D printed mini barrel project?

Question: My goal is to 3D print a 5 liter miniature barrel with a side stand, similar to this wooden one on Amazon. I want it to have a removable top so that a boxed wine bladder may be put inside, and there should be a hole on the top as well so that the spigot may stick out and be used. I have no experience with 3D modeling or printing, but I have access to a public 3D printer at my local library. I know you can print parts individually (ex. curved wood-colored sides with staves and holes to interlock and make up the body of the barrel, the metal-colored hoops to go around the barrel). I don't know what software to use, though. I was thinking of starting to learn Blender? Would that be effective for this project?
Comment: Just to add on here since several answers mention Autodesk 123D.  Autodesk 123D has been discontinued and they are now pushing users towards Autodesk Fusion 360.
Answer: Your question begins in an inappropriate format for StackExchange, but you've ended it with one more appropriate by asking if Blender would work.
If you are willing to take the time to learn Blender, you are certain to discover that it will do as you require, and much much more. Your referenced model could be created using engineering-type design software such as Fusion 360 or SolidWorks or many of the free packages, but the free-form aspect is more suited to the flexibility of Blender.

2020 UPDATE: Fusion 360 now supports a sculpt feature, which combines organic modeling with the engineering-type for which it is previously known.

Even though Blender is not an engineering-type program, it has internal support for precise modeling. Should you learn to use those features, you get the best of both types of software.
If you construct your model in the software in segments/pieces as you suggest, your result will have greater flexibility at the printing stage, specifically with respect to color and filament choices. Instead of wood-colored sides, you can use wood-simulated PLA filament! Depending on the printer at the library, you could also use filamet, a filament containing 88 percent metal for the hoops.
I use Blender for some aspects of modeling, often importing the STL into Meshmixer to address things I've not yet learned in Blender.
I hope your reference to 5 liter is the original size and that your model will be a miniature of it. A 3d printer with 5 liter capacity would be a wonderful asset at the public library!
Comment: I've forgotten something you may find useful. Our local public library has an agreement with lynda.com, a substantial learning resource. I have only now examined the material available. There are many hours of tutorial information specific to Blender on the Lynda.com web site. If your library has this available, it will facilitate your objective and save money too!
Comment: I like the dual approach of generating the measured parts in Fusion and then working out more organic parts of the design in blender.
Answer: I recently purchased a 3d printer and have found that freecad suited me really well http://www.freecadweb.org/ and its open source.
I believe its very similar to onshape in its a parametric modeller but runs locally rather that online.
Using the Parts view i have made most of my models using basic shapes and  boolen subtractions.
Answer: If you have any programming background at all, consider OpenScad. It is a functional type of programming language that lets you do a lot of things quite easily without art skills.  OpenScad skills are useful for building customizable things on Thingiverse.
Here is a place to start
Answer: We get this question a lot in the facebook groups I manage.
The usual answers do not include blender as it has a stupid hard learning curve. That is overkill for what you are looking to do.
Look into 123d from autodesk. Free if you do not make money. I find this one to be the easiest.
http://www.123dapp.com/design
Also there is Google sketchup, with SLT out plugin. I find this one is pretty sub par due to the fact it does not create printable models well (ie missing triangles so it wont create solids, hard to fix)
http://www.sketchup.com/
I think this one pops up. I haven't used it and I think it costs, but worth a mention.
https://www.rhino3d.com/
Answer: I think Autodesk Meshmixer is the best, as you can easily make parts with boolean operations(if you're more of a cubic thinking guy) or drag-and-sculpt(if you're more of a freeform guy). (And thoses videos are old but still working).
If you want to get better reflexes in CAD engineering, I think Solidworks is the best (but really expensive if you aren't an enterprise), if you want to get better knowledge in 3D design and animations, maybe blender is good but surely not for CAD people neither for beginners in 3D (even if it's well-documented).
Answer: I'm no expert, but have done some research on this question and it seems to me that Fusion 360 is currently your best bet. It's designed to do exactly what you're planning, from start to finish. Design (Sculpting and precision modeling),
Test (fitting/animation analysis), and Fabricate (CAM and 3D printing) all wrapped into one program that has a logical workflow, and is WAY easier to learn than Blender. It's free for hobbyists and startups making less than $100K/yr. There are a bunch of free tutorials online, professionally produced by Autodesk. By the time you get through those, you should be able to complete your project.
(Edit): I don't know anything about onshape.com. Like I said, I'm no expert.
Answer: You can check out Tinkercad. It is an easy to use, online editor.
Even though it is not as powerful as Blender or Rhino3d, for easy 3d models it is more than sufficient.
Answer: I would highly recommend you checkout Onshape for your design.
https://www.onshape.com/
It is the easiest to use, full featured, free 3D CAD program. It is made (and in active development) by the creators of Solidworks, the most widely used CAD program out there for good reason! And it runs in the cloud, so you don't need a high powered PC with an amazing graphics card, just a decent internet connection.
Onshape looks like it's going to be the future of mechanical CAD whereas other programs like 123d and Sketchup are simply lightweight versions of "real" CAD.
Unless you want to get highly involved in organic, complex shapes, I would avoid Blender, you will spend so much time learning it you could have whittled your barrel from a log instead.
Answer: To the people saying 123design. I can only say I have been a blender user way before 3D printing was a thing and just cant get around learning 123design. It just feels so limited as it only have a few tools. Yes blender might have a hard learning curve but it does pay off in the future as you wont be limited to 3D printing models and its crucial to make more complex models
Comment: I'm not sure if this is really suited as an answer. The question is a bad fit for stack exchange to begin with, as it tries to solicit opinion-based answers. Answers and questions should generally be based on facts and not opinions, so perhaps you can rephrase this to be more factual. For instance, in what ways is 123design limited compared to blender?


Using Image as button in Windows Form

Question: I am making an application using Windows Form and it will be used on a tablet that mainly use touch/tap for input. Is it okay if I am using Image for buttons? Like using image for add, save, delete, load, show/hide label, etc. Can you give me a web or references for designing Windows Form UI?
Comment: Is the text going to be part of the image itself, or will the text be applied over the top of the button image?
Comment: The button will only contain the image, no text at all. Is it good or bad?
Answer: This is a bit more of a coding & development issue than UX IMO.
Ideally you should try and use CSS/html/whatever you're using (not at all familiar with windows forms) to do it natively. Using an image for a button isn't good practice; it does have UX implications for accessibility (how does a blind person know that's what they've got to press?- hope you have a nice text label in the code) and it won't be great for people with slow connections.
Comment: how will a blind person know what they are pressing, even if the button is CSS coded?
Comment: Depending on the application (for future readers as well), a slow connection might be completely irrelevant. WinForms can be simple standalone desktop apps.
Comment: stanley - blind people have screen readers. Its a common accessibility problem for text to be contained in pictures and the code to not recreate this so that screen readers can see it.
Answer: It depends on the image. You don't just want a boring button with text, but at the same time, you don't want an ugly image. Try to stick to images for things such as add, save, close, etc. But keep it modern and 'nice' looking, making it very simplistic.
Answer: I have not worked with windows forms in particular, but a quick search told me that it is more accustomed to the desktop mode, like normal windows, than the touch friendly Win RT look. You can still develop desktop based UI as Windows 8 tablets will provide an inherent support for the same. I just wanted to highlight, that you might want to look at WinRT based UI approaches if tablet and touch is your primary consideration.
Considering your primary user is going to go with touch input, you'd want to keep an eye on the size of the image. It should take care of fat fingers and controls should not be placed very closely, else you'd have wrong actions trigger every now and then.
Also, a habitual user would be expecting buttons if he sees Windows Forms, so there should be strong reasons for deviation from customs. Also if you choose to use images you'd probably want to give special attention to affordance. Your image size, shape, color etc. should make it distinctively clear that there are actions to be performed on tap.
Currently your question talks about can you do it? and the answer would be yes, but for should you do it, we would need more inputs about the why part and what exact needs you are trying to meet.
I hope I have been of some help.

Using Image as button in Windows Form


Ubuntu doesn't work with 3d acceleration in virtualbox

Question: Running virtualbox on a pc. I have virtualization enabled in BIOS. Installed Ubuntu 12.04 32 bit on virtualbox without 3d acceleration enabled and it works fine, but when I enable it and restart, the desktop shows up but there is nothing on it or on the top menu bar. Things are clickable where they should be but you can't see what you're clicking. What's wrong?
Answer: You need to install the VirtualBox additions for your virtual machine and also enable the 3d support in your virtual box settings.
Have you done both?
Answer: I have also experienced this problem on a Windows 7 host, and as 3D acceleration is default for VirtualBox, it took me ages to find the solution. In my experience, it is an intermittent problem -  most of the time it did not work, occasionally it did work.
I installed VirtualBox additions but it did not resolve the issue.
This is what worked for me:

Untick the "Enable 3d acceleration" under display, and Ubuntu on VirtualBox is stable although slightly less glossy.


Money received from friend will be taxable? It was transferred to builder on behalf of friend from nre account

Question: I have transferred money (20lac+) on behalf of a friend to builder as slab payments from my NRE account. The friend is going to dispose old flat and pay back that amount. Can this amount be taken back in NRE? If this is transferred to savings will I have to pay tax? if yes how much tax? How can this tax be avoided / minimised? The friend is going to transfer higher amount than the amount received from me.
Comment: Could you add a country tag?
Answer: Assuming that your friend is residing in India, any money that he returns to you cannot be deposited into your NRE (NonResident External) account; it must go into your NRO (NonResident Ordinary) account. You don't have an NRO account, only ordinary savings accounts in India that you established before leaving the country and becoming an NRI (NonResident Indian) ? Well, you are in violation of FEMA regulations and need to convert all those ordinary savings accounts into NRO accounts as soon as possible. Your bank will help you in doing this (by letting you hold ordinary accounts while you have NRI status, the bank too is in violation of FEMA regulations).
With regard to taxation, unless you have created a paper trail by documenting the money sent to the builder as a loan to your friend, the entire amount (less INR 50,000 exemption) that your friend will return to you will be considered a gift from your friend to you, and it will be taxable income to you in India, and possibly taxable income to you in your country of residence, though there may be tax treaties that will let you pay taxes in one country only. If you do have a paper trail, then only the excess of what your friend returns to you is interest income to you; the bulk is just repayment of the loan principal, and is nontaxable.
If you are residing in the US, I do hope that you have reported the fact that you had foreign bank account(s) totaling more than US$10K in value to the IRS and the US Treasury as per FBAR regulations; because if not, you have many more tax issues to worry about. The fines for not filing these reports are onerous.
Comment: I am based in Dubai, UAE. Can take cheque in wife's name and deposit amount in my wife's savings account? Old bank statements downloaded have the mention of payments to builder with the amount which can be submitted as proof if asked.
Comment: Although the bank statements documenting the original transaction (loan) are important, I believe more is necessary. You should also have paperwork (a written agreement between you and your friend) describing the reason for the original transfer (loan) and other details.


If I have Schengen visa can I get Macedonian visa in airport

Question: I will have one business trip to Macedonia and will open Schengen visa for 1 year. Can I have Macedonian visa right in Macedonian airport? (I am not from Schengen zone)
Comment: What is your country of citizenship?
Comment: Kyrgyzstan (Central Asia)
Comment: You do not get a visa at the Airport - because you have a Schengen visa, you don't Need a Macedonian visa, as per the information in the answer
Answer: Timatic has information for Kyrgyzstan nationals traveling to Macedonia:

Passport required.

Passports and other documents accepted for entry must be   valid for a minimum of 90 days from the arrival date.

Visa required, except for Passengers with a double or multiple entry C
  visa issued by a Schengen Member State For details, click here. The
  visa must be valid for all Schengen Member States and be valid for at
  least 5 days beyond the period of intended stay in Macedonia (FYROM).
  They are visa exempt for a maximum stay of 15 days. (SEE NOTE 52764)
NOTE 52764: The max. stay is granted within 6 months.

Note also that a return/onward ticket is required. For reference, here is Macedonia's full set of visa information in Timatic.


Energy solutions for space

Question: One of the primary methods of creating power in space is by solar panels. However upon reading more about silicon based solar panels I got to know how even small dust particles can ruin the whole system. In space however dust is highly abrasive which increases the cost of mantainance of these solar panels.
My question (1st part): a new alternative to silicon based panels, namely perovskites doesn't pose this problem but currently this these solar panels are quite unstable. So which of these solar panels are more suitable for space.
My question (2nd part): for energy storage of batteries is preferable option. However for large space colonies is a Thermal Energy Storage System system preferred over batteries? (Since the extra heat can be rejected to these systems and heat can also be take from these systems to maintain temperature)
For both the questions, please suggest a better alternative.
Comment: You should probably ask two separate questions, since they are only loosely related.
Comment: Is this not a solved problem?  RTG, (small), or 'real' fission reactors, (large)?
Comment: "I got to know how even small dust particles can ruin the whole system." What do you mean by this? Can you add a link to what you've read on that, and why "...perovskites doesn't pose this problem..."? Do you mean during use in space, or during the manufacturing process?
Answer: I'll address the 1st part of your question first. This is a much more complex issue than the question implies. Asking, "...which of these solar panels are more suitable for space?" is similar to asking, "What type of house is best for living on Earth?" The best type of house depends on where on Earth it will be! Similarly, the best type of solar cell depends on where in space it will be providing power.
The "where?" question has to do with the environment the cells will operate in. The environmental conditions of principal interest to power system engineers are sunlight intensity, temperature, and radiation. If the panels will operate in a region of high-velocity dust particles, that dust can influence the array design as well.
Sunlight intensity has a huge impact on array design. Solar cells have powered spacecraft at heliocentric distances all the way from Mercury (and even a bit closer, to ~0.3 AU) to Jupiter (~5.2 AU), for a factor of ~300 difference in sunlight intensity. Different cell chemistries and structures (such as single-junction or multi-junction) are better in different parts of that range.
Sunlight intensity is closely related to temperature: typically, in the absence of a relatively dense atmosphere or some kind of concentrator, higher solar intensities produce warmer arrays. This can be modified somewhat by controlling the thermal radiation from the arrays' back sides, either by insulating to keep them warmer or providing a high-emissivity radiating surface material to keep them cooler, or by off-pointing the arrays to keep them cooler by reducing the total sunlight power impinging on them. There are limits to keeping arrays warm without concentrators: insulate as you like on the back side, at 20 AU the arrays will not be at room temperature!
The combination of low solar intensity and low temperature is a problem of special interest to outer solar system exploration, with an assigned name: Low Intensity Low Temperature (this reference also treats radiation effects), "LILT". As intensity and temperature decrease, cell performance decreases, and the magnitude of the decrease differs significantly from cell to cell. In a given string of several cells (to get the voltage up to where it's needed), the worst performer limits the string performance. Hence the "selection program" approach used by Juno: you test each individual cell (Wow! Expensive!), and the bad performers are tossed out. Actually, those bad performers work just fine under "normal" intensity and temperature conditions, so they are sent back to the manufacturer for use in other, less demanding applications. Some chemistries, such as GaAs, do better than others under these conditions, especially the multi-junction types such as used on the Dawn spacecraft. If research produces a perovskite chemistry that is amenable to the multi-junction architecture, they might do well also.
Why not just use concentrators in the outer solar system, avoiding the LILT effects? Like spacecraft directional radio antennas, solar concentrators are "beamy": when pointed correctly, performance is great, but the performance drops dramatically as pointing errors increase. This is a bad situation for spacecraft emergencies: if you lose pointing control, you lose your main power source too, and the spacecraft's battery capacity limits the time you have to resolve the emergency and get those arrays back on sun-point. This risk has kept reliance on concentrators out of flight mission architectures to date, except for technology demonstrator missions such as NASA's Deep Space 1.
Radiation is also a concern in certain environments such as orbiting Jupiter. Particulate radiation causes lattice defects in the semiconductor, and these defects act as recombination centers for the electrons and holes, converting the energy that would have become usable cell output into heat instead. Cell chemistry influences this sensitivity, and in turn that sensitivity is influenced by the type and energy spectrum of the radiation. In the face of a high-radiation operating environment (such as Juno has, especially in the later orbits), power system designers opt for the cell chemistry best suited for the radiation environment.
In summary, the large range of environmental conditions encountered in the solar system make it very useful to have multiple solar cell chemistries and architectures available. No single chemistry and architecture is a "one size fits all" solution.
Comment: Interesting answer!
Answer: Space dust poses a problem to solar panels not because it's abrasive, but because it arrives at a high enough speed to punch a hole in the solar panel. You can't solve that by going to a different material. You'd have to switch to a much heavier structure, with a transparent panel in front of the solar cells working as a Whipple shield.
Perovskite isn't a semiconductor, so I don't see how it can be used as a solar panel.
Thermal energy storage works if you have temperature differences you can exploit: the bigger the difference, the more efficient your storage becomes. For spacecraft, heat rejection is difficult and requires bulky radiators.
Colonies on a planet or moon might be able to use thermal energy storage, but traditionally, these systems require large amounts of a liquid to transport the heat so they might again be too bulky to be efficient.
Comment: https://en.wikipedia.org/wiki/Perovskite_solar_cell Because it's not a semiconductor based on a crystal lattice with a very large size (like single crystal or large grain poly), it in fact might handle localized damage due to tiny impacts better (less leakage or recombinations) than a polycrystalline material. I don't know, but "You can't solve that by going to a different material" might not be 100% correct.
Comment: Just as big of a problem, depending on your specific location in space, is particle radiation, which creates defects in the semiconductor junction.

Energy solutions for space


What is the distinction between "reduce" and "suspend" in the context of government action?

Question: I am curious about the distinction between the term "reduce" and "suspend" in the context of government action, specifically as to whether or not the term reduce would require permanence. For example: If the government were to "reduce" its arms sales to a certain country, would that mean that reduction is permanent or would the government restart sales later on? Would it be appropriate to say that a reduction of government arms sales could be temporary?
Answer: English
The difference between "reduce" and "suspend" is linguistic, not legal. "Reduce" means to continue but at a lesser level than previously, it has no connotation of duration, for example unemployment might be reduced this month but could go either way next month. "Suspend" means to stop completely but with an implication that such stopping will be reversed in the future - possibly if specified conditions are met.
Legal
Governments can always change their policies subject to any legal restriction.
Assuming there is no legal impediment on "arms sales to a certain country", a government, can reduce, suspend, stop, restart, increase, suspend again and so on indefinitely.
Comment: @JordanDi No, there is no such implication in the use of the word "reduce". Something can be reduced for 2 minutes, 2 days, or 2 years, and then suspended, halted permanently, or increased to a level higher than it was before the reduction. Or the reduction can turn out to be permanent. Temperatures were reduced during the last Ice Age, but not forever.
Comment: In the linguistic sense, would a reduction preclude a suspension i.e. if something is reduced, it is permanent?


Printing to a printer that is not defined on the machine

Question: I am looking for a solution to programatically print a file to a printer that is not defined locally.  What I would like to do is send the file to printer perhaps by specifying the printer address (\MyPrintServer\PrinterName) and give it a print driver.  Does anyone know if this is possible and if there are any open source or relatively cheap options available?
Answer: You mean you want to print on a network printer that is not connected to your pc? I guess you have to connect it first before printing anything. If you want to connect it using code, then this might help you: http://msdn.microsoft.com/en-us/library/windows/desktop/ff686807(v=VS.85).aspx .
Answer: To clarify, I assume that you have a server and you want to print from a client computer. Also, if for any reason you don't have a driver install on the server, you would programmatically install the driver from the client-side. If so, I could possible be of help to you.
Also, check the link from Bogdan0x400.


What makes the Balance of Payments (BoP) to imbalance?

Question: Theoretically the capital account balance should fully offset the current account balance and the BoP should be zero for any economy. What causes the imbalance or discrepancy in the overall BoP ? What makes countries run BoP surplus or deficits ?
Answer: This depends on the exchange rate regime. For a floating exchange rate, the balance of payments is always in equilibrium, that is, the financial account always offsets the current (and capital) account. A hypothetical deficit is avoided by a depreciating exchange rate, a hypothetical surplus is avoided by appreciation.
For a fixed exchange rate regime, the central bank will offset the exchange rate adjustments that guarantee the equilibrium under floating exchange rates. In order to offset these adjustments, the CB has to intervene in the exchange markets. To prevent a currency from depreciating, the CB has to use its foreign reserves to buy its own currency. To avoid an appreciation, the CB has to buy foreign currency and icrease its foreign reserves.
To sum up, as an answer to your question: BoP imbalances only occur in a fixed exchange rate regime and are caused by foreign exchange interventions of the CB. Therefore, the imbalance is equal to the settlements balance, or the change in the CB's reserve assets.
Comment: But why then almost every country has some imbalance i.e. either a BoP deficit or surplus. Even countries with highly flexible exchange rates like the United States.
Comment: This deficit refers to a current account deficit. I haven't checked the data for US specifically, but the deficit on the current account should be offset by the capital account. Unless the Fed is intervening the exchange market, but I do not believe that this is the case.
Comment: Maybe I was a bit confused between the definitions part. The reserve transfer transactions between central banks is not accounted in the capital account. It is added separately in the BoP . The BoP surplus or deficit that we hear about is actually the sum of Current Account balance and Capital Account balance and not the reserve transfers.
Eventually, the sum of BoP surplus or deficit plus any reserve transfers plus any statistical errors will always sum to 0. Thanks a lot
Comment: Please note my edit. I mistakenly used "capital account" instead of "financial account" in my post. I corrected this error. In my comment of Dec 5, capital account should also be changed into financial account. If you check the data, you will note that the capital account is generally very neglegible.
Answer:
According to the IMF's BPM6, which should be taken as the "most" standard, it is impossible for the BOP to be out of balance.

In the IMF BPM6, BOP simply refers to a statistical statement (think of it as a piece of paper or an Excel spreadsheet) that records, in summary form, all of the country's international transactions. The BOP never refers to a number. Hence, there is no such thing as a BOP surplus or a BOP deficit.
The three accounts in the BOP are the Current Account (CA), the Capital Account (KA), and the Financial Account (FA). In theory, it is always necessarily the case that: CA + KA + FA = 0. (In practice, we have to add an "errors & omissions" term.)
Hence the name balance of payments. The above balance of payments identity must always hold.
Unfortunately, not everyone follows the IMF's recommendation. This causes a lot of confusion.

Some countries break up the BOP in a different way and DO refer to the BOP as a number.

For example, Singapore takes out "changes in official reserves" (ΔR) from the Financial Account and combines what is left of the FA with the CA into a single account called the Capital & Financial Account (KFA).
And so for Singapore, the BOP identity can be written as: CA + KFA + ΔR = 0.
And very confusingly, Singapore then defines BOP = CA + KFA = -ΔR. Hence, in Singapore, a BOP surplus refers to when there is an increase in official reserves (yes, strangely enough, ΔR < 0 ⇔ official reserves increase). And a BOP deficit is when there is a decrease in official reserves.
Singapore's presentation of the BOP is actually not so unusual. The IMF BPM6 for example does suggest it as a possible alternative presentation of the BOP (see end of p. 224 and start of p. 225). However, I think it's pretty unusual to define the BOP as a number equal to -ΔR, as Singapore does.

Journalists frequently speak, mistakenly, of a BOP deficit, when they really mean a trade deficit (or, what is slightly different, a CA deficit).

This obviously adds a lot of confusion to an already confused situation.


What's the song when Bishamon fights in episodes 11 & 12 of Aragoto?

Question: What is the name of the song in Noragami Aragoto episodes 11 and 12 when Bishamon fights? First, against Izanami in the underworld, and then against Kiun, the Thunder Dragon, immediately after rescuing Ebisu from a direct strike.
Answer: Assuming you mean the music that starts at about 18:18 in episode 11 and 16:25 in episode 12, that is "Distortion" from the Noragami Aragoto OST (disc 1, track 4). Here is a 20-second extract from the beginning of the track.


Is human nature necessarily metaphysics? Is it not possible to have an account of human nature that doesn't involve metaphysics?

Question: I'm working on an MA Dissertation on MacIntyre's thought. And I find that from his earlier rejection of Aristotelian metaphysical biology, he moves back into discussing human nature in a very Thomistic fashion. But my guide is quite disappointed with that, since he feels that we live in a post-metaphysical world, and that there is no thrill in reviving Aristotelianism if it is still metaphysical. I don't understand why that needs to be case. Is human nature necessarily a metaphysical concept?
Answer: Of course there are accounts of human nature which are not based on metaphysical concepts. You may take any contemporary textbook on psychology, e.g.,

Zimbardo, Philip: Essentials of Psychology and Life
Pervin, Lawrence; Cervone, Daniel; John, Oliver: Personality: Theory and Research"

and read about the methods and concepts used to investigate human nature, i.e. human affects, behaviour and cognition. Psychology has changed into an empirical science. It is not restricted by any traditional a-priori conception of human nature.
In addition, it is very risky to rely on Aristotle's basic concept nature. Sometimes he draws quite wrong conclusion from the concept, e.g.,

He then is by nature formed a slave who is qualified to become the chattel of another person [...]. Politics V, 1254b.
Answer: There are many confusing definitions and ideas about what Metaphysics consists of; I like Aristotles, where he also calls it First Philosophy; he takes it to be an investigation into the first principles of nature.
To give an account, then of human nature, must then ground themselves into what these first principles are.
If a first principle is God, or Brahman or Allah; it seems that we must ground human nature there; and this is done, for in Christianity - we have the nature of the soul, in Hinduism - atman, in Islam - ruh.
In a framework where these are not accepted, say modern empiricism, then they are grounded naturally - in the mind, or subconscious: so Freud, Jung and Lacan.
So yes, by definition a full account must take metaphysics into account; a partial account will not, neccessarily.
Answer: One of the challenges of exploring human nature physically is that, in our culture, the opposite of metaphysics is science.  Functional physicalism actually makes the claim that human nature is explainable by the structure of a physical world.  However, when we think of physics, we think of science.  We think of the scientific method, testing  hypotheses, and statistics.
This proves difficult when exploring the human condition, because typically one thinks of onesself as part of the human condition.  One can test others scientifically, and make statements about how they operate.  However, while exploring this, you have to ponder whether you are part of this "humanity" that you study.  To resolve this question, you have to turn your study onto yourself.
However, there is a great challenge here.  Science is extremely dependent on well controlled experiments.  We take great effort to blind experimentees from knowing too much about the experiment, for fear of it ruining the results.  However, it is impossible to do this on yourself.  Thus science has a hard time grappling with the self, and physics thus has a hard time with it, simply because many of us define physics by science.
Relaxing the rule that physics is not always science, many other physicalist approaches become valid.  Also, decreasing the formality of the language makes more approaches valid, if for no other reason than its increased ability to draw upon the human condition.


Time limit on making a Siyum

Question: Suppose one learned a complete Mesechta and is just about ready to make a Siyum. Is there a time limit as to when he should make the Siyum? Can he wait 3 months to complete the last few lines?
Comment: related http://judaism.stackexchange.com/questions/1354/making-a-siyum-on-a-mesechta
Comment: Haven't we all learned the last few lines of most masechtot already anyway?
Comment: The "siyum" seems to be merely the celebration which if you haven't done yet, could be done at any point in honor and celebration of completely a part of the Torah. Even if you read off the lines already before. I finished learning mesectas Niddah already more than a month ago and didn't read the last few lines -- even though I obviously know what they say...The "siyum" was not made yet as I pushed it off in light of Purim and Pesach...Waiting for a good time (won't do it during the 9 days though...)
Comment: @DoubleAA, depends on the masechta, depends on the person.  If there are people regularly making siyumim somewhere you frequent, then yes, perhaps.  But if asked "What is the end of Masechet Ploni?" there are fairly few values of ploni for which I have a ready answer.
Comment: @Ploni done ! [    ]
Answer: The only sources I found on this come courtesy of chaburas.org and say one can wait a bit but not a lot.

Maharam Mintz claims that when one reaches the end of a tractate, he
  should delay learning the end until an appropriate time comes for
  making a siyum. Minchat Yitzchak (2:93) qualifies this by
  distinguishing between waiting a little and waiting a lot. One who
  finishes a tractate the week before Pesach may draw out his learning a
  bit so as to make a siyum on Erev Pesach, but one who finishes in
  December should not save the last page for the four months until he
  needs it to avoid having to fast. He says that in such a case, one's
  siyum would not be made out of simcha, but rather out of a desire to
  satisfy one's physical needs.

Regarding a siyum during the nine days specifically see here

However, those who complete a significant portion of learning (e.g. a
  tractate of Talmud) during the nine days solely for the purpose to eat
  meat are not universally praised. In fact, the Aruch HaShulchan, while
  allowing such behavior (suggesting that at least in this way, people
  will learn Torah) does limit the people participating in this meal to
  just Torah scholars associated with this learning project [Aruch
  HaShulchan Orech Chaim 551:28].
Nevertheless, the Mishna Berura, among
  others does allow broader participation in the meal, extending it to
  all those who would normally be invited to such a celebration [Mishna
  Berura 551:75].   Once the week of Tisha B'Av begins (from the Sunday
  before Tisha B'Av), the number of participants at such a siyum should
  be limited to a minyan aside from the relatives of the person making
  the siyum and those who are helping with them meal [Orach Chaim
  551:10; Mishna Berura, ibid. note 77].

Time limit on making a Siyum


Finding A String Using A Suffix Array/Table

Question: Is it possible to find out a string only having its corresponding suffix array/table and knowing that the string contains only, for instance, letters "f", "g", "r"? If so, how is that possible?
Answer: Sure: the longest stored suffix is the string itself.
In a suffix array, it's particularly easy to find: scan the array for starting index $1$ -- the suffix starting at the first character is, quite obviously, the string itself.
Answer: Understanding the definition of a suffix array will come in handy here.
http://en.wikipedia.org/wiki/Suffix_array
Suffix Array for the string attcatg$.

So like Raphael Suggested either look for the index 1 string attcatg$ or look for the longest string in that array which is the same if it doesn't store indices but it should store indices as per definition.


How to update all posts at once?

Question: Like "after host change, we update our permalink"
Comment: i try to finding ans from stackexchange but no ans work for me.
Comment: No one !! :( :(
Comment: ...it's not clear what you're trying to accomplish. Maybe try a fuller description?
Answer: I think you want to mass change old URLs in website database after migration. You can do it either by using plugin or manually.
Plugin Method:
The Velvet Blues Update URLs plugin enables you to change the URLs at various places, like posts and pages excerpts. Follow these steps:

Install and activate Velvet Blues Update URLs plugin.
Head to Tools > Update URLs.
Insert the old site address in the Old URL field.
Insert the new site address in the New URL field.
Check the boxes in front of URLs in page content, URLs in
excerpts, URLs in links, URLs for attachments, and URLs
in custom fields and meta boxes.
Finally, click on Update URLs NOW button.

Manual Method:
There are various ways of mass changing old URLs manually. They are:

Changing the URL directly in the database
Use PHPMyAdmin script for Search and Replace in Database

You will find the details of the manual methods right here.

How to update all posts at once?


I'm not sure if I'm executing these instructions on piano time signature correctly

Question:
I'm learning piano on my own and I'm using a workbook (Ben Dunnett). Below is the link to my interpretation of what this task is asking (video on YouTube). I know I've played this in common time as I'm following my metronome (Stage Metronome for Android), but I'm having a hard time playing according to the instructions: emphasis the first beat of every bar by playing it a bit louder. What is throwing me off is the notes: it's two pairs of crotchets, each in the same key so I keep playing 2/2 instead. I know 2/2 is 4/4, but I'm having a hard time playing the "emphasis on the first beat of each bar". I've tried singing it and tapping to it and I'm still having a hard time figuring it out. What is this supposed to sound like?
Answer: The difficulty is comprehensible due to the way the notes are placed (and that's also probably part of the exercise).
I suggest you to start doing some exercises with a single note, with a strong accent only on the first of each group, trying to ensure that the accent only changes the volume of the note, not its duration, as in your video you're playing every first note much shorter than the second.
Do it for every finger, with 4 notes for finger, forward and back, then the same with 3 notes per finger (3/4), and then 2 (2/4).
These exercises would be written like this
X: 1
K: C
L: 1/4

[M: 4/4]||:!>!CCCC|!>!DDDD|!>!EEEE|!>!FFFF|!>!GGGG|!>!FFFF|!>!EEEE|!>!DDDD:||
[]
[M: 3/4]||:!>!CCC|!>!DDD|!>!EEE|!>!FFF|!>!GGG|!>!FFF|!>!EEE|!>!DDD:||
[]
[M: 2/4]||:!>!CC|!>!DD|!>!EE|!>!FF|!>!GG|!>!FF|!>!EE|!>!DD:||

Notes: the double bars with the points indicate a range of repetition: sections enclosed between ||: and :|| (sometimes the first ||: can be missing) are generally repeated twice; in this case, every group of 8 bars should be repeated at least twice, but being it an exercise, you can do them even more times if you feel so; the > symbols mark the accents, placed over or under the notes that should be "emphasized".
Then, again from the beginning, but with using accents less strong than before (but still audible).
Finally, the same exercises, but trying to play the accent only every two bars.
Then do what the exercise proposes, but by repeating every bar at least twice. As above, try with bigger emphasis on the accents first, then softer. In any case, always ensure that the duration of the notes doesn't change.
You can help yourself by also doing those accents by singing without playing, always ensuring that you properly do both the accents in the downbeat and that durations are consistent, then play while singing along.
Also try to keep your wrist a little bit lower (just a couple of centimeters).
Note that you're playing a wrong note: the third and fourth note of the first and third bar are "F sharp", so you need to play the black key immediately to the right of the white key you're playing in the video. This is referred to the two "#" (sharp) symbols that you circled in your book: those are "accidentals", are used to specify the key of the piece (in this case, D major) and are valid throughout the whole piece (unless specified). In your case, every F and C you would see in the piece should be played as sharp (the black key on the right of F and C).
This is how the result should be.

Note: from what I can see, you're still a bit confused about many aspects, and it's possible that the excercise is still a bit difficult for your knowledge and experience. Maybe you need to do some more practice and review your previous studying (including theory) in order to make you more aware of those aspects: they are very basic, but also fundamental for your musical education; the more those are clear (and the sooner), the better you'll learn in the future. Do not try to push your learning by hurrying too much.
Answer: Don't worry too much about 4/4 and 2/2.  In both of them the primary accent is on the beginning of the bar, there's a secondary one half way through - on 3 of 4/4 or 2 of 2/2.  And it's a lot less pronounced than you think.
Your problem is that you're 'picking' at the first of each repeated pair, playing it short.   Keep your hand closer to the keys, PRESS the louder notes rather than striking them.
You might find it useful to practice this, concentrating in keeping each note the same length.
Answer: Most rhythms have the 1st beat of the bar emphasised. That's basically how the rhythm of the piece is established.
Get used to counting out loud - '1-2-3-4-1- ,2-3-4, and make 1 count on the different sound of the metronome. The one that has a higher pitch. For now, regard that as beat 1. There may also be a flash from a led at that moment each bar, too.
When that's good, play just 1, and wait until the next 1, when you play it again. Make it as loud as you like,then for now, play the same note 3 more times, counting 2-3-4.
It's clear that the exercise is a little advanced for now, so come up with simpler versions - like te one I explained. Little steps are normally going to get you there faster, so break down everything!
Answer: 2/2 vs. 4/4
The insight that 2/2 and 4/4 have different accent patterns is important. The differences between similar-seeming time signatures is a much discussed topic on this site in its own right. For example,

Is there any real-world difference between time signatures such as 4/4 and 8/8?
Is there a difference between 2/4 and 4/4

as well as the questions Linked and Related to those.
Exaggerate the accent(s)
When trying to create contrast in music, I like to begin by grossly exaggerating the contrast. It's easier for me to then pull back to a musical level, as opposed to starting too conservatively and then needing to "open up".
The techniques and exercises in the other answers are all good; take those to heart. A couple of my own suggestions:
Emphasizing beats 1 and 3
Since 4/4 has its main accent on beat one and a secondary accent on beat 3, and keeping in mind the idea of exaggeration, I suggest an exercise like this:
X: 1
T: 4/4 with Exaggerated Accents
M: 4/4
K: D
L: 1/4
!f!!>!D D !p!!>!F F | !f!!>!G G !p!!>!A A | !f!!>!D D !p!!>!F F | !f!!>!G G !p!!>!A A |]

In effect, you're dividing each 4/4 measure into two 2/4 measures, playing the first 2/4 measure forte (loud) and the second 2/4 measure piano (soft), with accents at the beginning of each 2/4 measure. Make sure there's a clearly audible difference between the forte and the piano parts. (Specifically, the forte accent should be noticeably louder than the piano accent.)
This provides a starting point for getting both the strong beat-one accent plus the less strong third-beat accent.
NOTE: the ">" is an accent sign, meaning to stress that note relative to the current overall dynamic (volume) level.
Toward a more realistic 4/4
Once the above exercise is comfortable, the next step is to move toward a less exaggerated execution. Something like this:
X: 1
T: 4/4 with Exaggerated Accents
M: 4/4
K: D
L: 1/4
!f!!>!D !>(!D !>!F F!>)! | !f!!>!G !>(!G !>!A A!>)! | !f!!>!D !>(!D !>!F F!>)! | !f!!>!G !>(!G !>!A A!>)! |]

The distinction between this and the previous exercise is that rather than an abrupt shift between f and p, there will now be a more gradual quieting. The accent on beat 3 will still make it a bit louder within the context of getting quieter overall.
Hand position
Keeping your wrist lower is good advice. Your hand shape is part of the reason it's so high. "Soften" your thumb so that the space between it and your pointer finger is less, and don't play on your fingertips; instead, play slightly toward the pads of your fingers. There's a halfway point between the finger pad and finger tip that is ideal. The effect to look for is that your hand will be slightly flatter, your wrist will be lower, and your entire arm will be more relaxed.
There are pictures on this site of what I consider good hand position:

Sore left hand holding chords in awkward positions for long durations
Why finger 4 on G-sharp, finger 5 on Fx=G in Moonlight Sonata mvmt. 3?
Comment: I just noticed that the hand position is not so bad at the beginning of the video (but fingers are a bit too "closed"). Unfortunately, the wrists moves up too much exactly when the OP begins the exercise more correctly. Good point on explaining of the accent symbol, btw.


Is poor English grammar and writing style overlooked in otherwise strong math paper submissions?

Question: Is poor English grammar and writing style overlooked by peer reviewers and editors in otherwise strong math paper submissions?
Comment: My first single author paper was rejected twice for poor writing, despite being a very good paper. I only published it when my writing style improved. I published since many weaker papers.
Comment: I would venture to say this pretty much depends on the English level of your research community.  In some areas, there are many more non-native English speakers.  Hence, assuming the paper is readable, then it is usually acceptable.
Comment: @Prof.SantaClaus: The worse the reader's English is, the harder it is to understand incorrect English. Native or highly experienced English speakers will automatically correct many mistakes that can completely throw any less experienced speaker.
Comment: It depends. Reviewers can and often do state in their reports that the language is in dire need of improvement. As long as the ideas have been communicated understandably, they may or may not bother. If the style is very bad, then that needs to be addressed as well. The major publishers have language editors (though I don't know if that is a dying art/profession). Also, in many universities world wide, departments of English language offer their help (even though sometimes their suggestions are hilariously wrong due to special properties of math lingo).
Comment: I rejected a paper because I literally could not understand their methods. I *suspect* that they made a mistake but it's entirely possible that I was wrong. My "reject" was worded similar to "methods need to be revised substantially before resubmission".
Comment: You can't assume that it is, since - what's stopping someone from _not_ overlooking that and being biased against your paper? That can always happen.
Comment: There is a huge difference between *poor grammar* and *poor writing style*. I occasionally run across papers written by non-native speakers that contain numerous grammatical errors, but are still clear and very easy to read. On the other hand, bad writing style can make papers—even ones written by native English speakers—nearly incomprehensible.
Answer: Short answer: no
Longer answer: The purpose of the article is to communicate something. If poor grammar and style gets in the way of that goal, then that is something that needs to be addressed before the article can be published. If the paper is indeed strong, then that will typically mean you will get a "revise and resubmit" rather than an outright "reject".
Comment: +1 I often teach postgrads from non-English-speaking backgrounds.  Some of them use imperfect English, but are perfectly clear.  Others use imperfect English and I can't make head nor tail out of it.  It's when the imperfect English gets in the way of communication that I penalize the students. I give the clear comms, but imperfect, ones feedback, too, but generally not in the form of lower grades.
Comment: FWIW there's many services you can use before you submit a paper to fix those kinds of mistakes. Being at a university, there's probably someone on campus who will do it for a price. And I highly suspect it's easier to fix the grammar and typos (matter of hours) than it is to produce strong mathematics research (years upon years upon years)...
Answer: Sometimes (as a referee for a submitted paper) I have provided detailed grammar corrections1.  Other times I have just said: "The English is unacceptable, get someone more expert in English to correct it for you."  I do seem to recall in one case the editor told me that the journal staff will correct the English, so I should not worry about it, instead only worry about the technical content.
1 éventuel does not mean eventually
Comment: On a par with "eventually" is "actual". In both cases, the similar-looking words in all languages that I'm acquainted with, except English, have the same meaning, but the English meaning is different.
Comment: I once sent the same reply, after less than 15 minutes of review. Even the statement of the theorems included serious grammar errors, and the proofs couldn't be followed. The contents could have been Fields Medal material; no one would have known.
Comment: If the editorial team correct the English *after* you have reviewed it, what guarantee is there that they would not introduce errors at that stage?
Comment: @AndrewLeach: I don't think this is referee's job to find and fix all mistakes. In particular, the responsibility for those included at post-review phase lies solely with the journal staff and the authors, whether they fix the grammar or not.
Answer: Are you asking about the "should" or the "is"? It depends on the referee and the editors. I have seen papers published in top venues that would have seriously profited from 5 minutes of proofreading (sometimes even from an automated spellcheck). But I have also seen referees point out rather subtle linguistic errors carefully and in detail (and have done so myself a few times). There is probably no shortage of referees who are willing to rubber-stamp a paper written by a celebrity no matter whether any of it makes sense. I also wouldn't be surprised if an editor feels pressured to publish a paper by a VIP even despite the objections of referees.
There is also a huge distinction between the kind of errors that merely reveal the author to be a foreign speaker, and the kind that make reading difficult. On occasion, a language barrier completely prevents the author from readably communicating a proof; while I cannot blame the author for the "mistake" of being born in the wrong country, I don't hesitate to send back such a paper for revision, after giving as many suggestions as I can (and as concrete as I can) for how the writing could be improved and what pieces of syntax they seem to be missing. Things like this should not lead to rejection of papers, unless the author fails to clarify their work through several revisions; but the paper should not get accepted until this work has been done.
Comment: @cfr: double-blind cannot work in the presence of the arXiv. I would guess it's on its way out in other disciplines as well...
Comment: It is still on its way in in mine. There are compelling reasons for double-blind, which is not to say that there are no costs, of course.
Comment: Double-blind review still not standard in your discipline, then?
Comment: +1 for emphasizing the difference between reality and good judgment.  Reading the question itself, it sounds like something anyone might ask rhetorically after flipping through the pages of some journals in some fields.
Answer: It may or may not be so with the referee, but it is rarely overlooked by the readers.
Few researchers have the luxury of spending time deciphering bad grammar and convoluted sentence structures: battling typos is more than enough.  Moreover, if the community is left with the impression that you write poorly, they will shun your work unless it is brilliant.
Too many spend months working on a project but limited time thinking about presenting the results in a reader-friendly manner.  Good grammar, the systematic use of a spell-checker, and adequate clarity result in a win for the authors and the readers.
Answer: This question really makes me remember a good editor, who gave me an opportunity to revise my paper even if the paper was really written by very poor English. That was two years ago, when I submitted my first paper, I got rejections almost from everywhere because of the poor paper writing. Finally, the paper was publicized and now I am a second-year PhD student with 6 papers in hand. They are not top journals but they are all in Q1.
All professors grow up from young students. I believe everyone produced bad papers when they were young. It is true that the paper must be publicized in a good format otherwise readers will get confused when reading papers. However, the editor could do more than a rejection. If the paper really has some good things, such as good idea or math, maybe one more opportunity from the editor will give the world one more good professor.
Thanks to the editor.


How did Andy Dufresne dig the tunnel if there was another cell next to his?

Question: In The Shawshank Redemption (1994), how did Andy Dufresne dig a tunnel if there was a cell next to him. He had to go through it, yet he obviously didn't.
Comment: This question is based on faulty logic...
Comment: No, it's not.  Your response is based on a faulty understanding of the prison layout.  ;o)
Comment: Does anybody have a map of the prison?
Answer: His cell was the last one on the row, so there was no cell next to his.
Edit: I should say, his cell was the last on the row and only had 1 adjacent cell to the left and he dug out a hole on the right wall.
Answer: Andy, as both a model prisoner and a cog in the warden's money laundering scheme, was given 2 priveleges; the last cell on the end of the row (a coveted cell for Andy because of its distance from most activity, which made it quieter), and a cell of his own.  You may recall that he didn't set out to dig a tunnel, it just started when a chunk of the wall fell out while he was etching on it.
As a result of his 2 privileges, he was able to dig a hole in the wall that led to the sewer pipe, and he was able to do it undetected since he didn't have a cellmate.
Comment: I agree about the cell of his own, but was the cell at the end of the row really a privilege, and not just chance?
Comment: While I can't find any direct reference to it on the Internet, it was always my impression that Andy got that cell because he preferred a quiet environment.  Don't forget, this was **after** he was raped by "The Sisters", and the warden had one of them summarily butt-whooped.  In the book it states that he had a roommate for a short period of time, I recall.
Comment: I don't think _any_ of the prisoners is shown to share a cell.
Answer: If you watch the scene where the warden discovers the tunnel. This is an end cell. The camera goes to the window sill and now from the back of the cell, he throws the conspiracy theory along with the rocks at red and the guards their backs are to the common cell wall. And Fuzzy Britches is hung on the main retaining wall of the prison.
Although when they first call Dufresne and the cell is shown from the first level from that angle you can't see the poster.


Choosing Oscilloscope with appropriate bandwidth for Jitter analysis

Question: Can someone give me a rule of thumb of choosing Oscilloscope with appropriate bandwidth for the Jitter analysis of clock signals? What device is highly preferable: spectrum analyzers, frequency counters, real time scopes Or Sampling scope with clock recovery?? Which is highly preferable of getting accurate jitters measurements? I need to measure between 10 Mhz - 10 Ghz signals?
Comment: To an extent it matters what you want to know - worst case?  Or distribution of variation?  For variation-type tests, a quiet spectrum analyzer is convenient, though a carefully constructed `notch filter` to reject the center frequency can be used to make it easier to see the noise bands with a cheaper instrument.
Answer: I'd consider investing my time and money in a phase locked loop (PLL) and VCO circuit - use a long time constant and build a very steady circuit - not hard to achieve but will save you a lot of money. Input the signal you wish to measure jitter on and look at the control signal to the VCO before it gets filtered - if there is a lot of jitter it will show up here and there is enough "information" in that signal to calculate jitter.
I hate spending lots of money on one-off equipment if at all possible - that's the motive for my answer.
Answer: To choose an Oscilloscope you would need the highest frequency you will encounter in your measurements and the you can apply the Nyquist criteria (fs > 2 x fmax ).
Jitter measurements aren't really affected by the scope, since jitter isn't an increase in frequency it's a movement of the signal in time.
Since you need to measure signals up to 10 GHz you would need a scope of 20Ghz which is a very high bandwidth scope and will probably be a very expensive scope, I'm currently working with a 15GHz one and that is already a "good" cost. What signal are you trying to analyze ? RF, Serial Data, ... ?
Some very usefull Application notes:
Don't know if needed but here: Jitter—Understanding it, Measuring It, Eliminating It Part 1: Jitter Fundamentals": http://www.highfrequencyelectronics.com/Archives/Apr04/HFE0404_Hancock.pdf
"Evaluating Oscilloscope Bandwidths for Your Application": http://cp.literature.agilent.com/litweb/pdf/5989-5733EN.pdf


Why are Presidential primaries usually a landslide for the incumbent?

Question: An incumbent President has only been denied his party's nomination five times, and only once did the incumbent initially become President via election.
Why are Presidential primary elections usually landslides for the incumbent if they are running?
Comment: Note that primaries can and sometimes are cancelled altogether https://www.politico.com/story/2019/09/06/republicans-cancel-primaries-trump-challengers-1483126
Comment: @hszmv the question is asking about results in the Primaries, not the General. Where [Obama](https://en.wikipedia.org/wiki/2012_Democratic_Party_presidential_primaries) [Clinton](https://en.wikipedia.org/wiki/1996_Democratic_Party_presidential_primaries) and [Bush](https://en.wikipedia.org/wiki/2004_Republican_Party_presidential_primaries) did indeed secure landslides of over 80% of the vote.
Comment: Probably due to primaries. All of the "upsetting" results you mention were in the days of the smoke filled back rooms (i.e. before 1900).
Comment: Just a note that "Landslide" typically means above 80% of the vote.   The last U.S. President to be elected in this threshold was Reagan in 1984, who won 49 states to his opponant's 1 plus D.C.   Clinton, Bush (George W.), and Obama never secured landslide.
Answer: The only way someone can answer that this is incorrect would be to argue that the proper adverb is "always" rather than "usually".
The thing about a sitting president is that in general, they've already shown they can do the job, and can get elected in a general election to do that. None of their primary challengers can say that.
In addition, a President is the uncontested leader of the party, which has very real consequences, such as appointing the leadership of the national committee (DNC or RNC) that runs the entire primary process.
Nobody is going to challenge that, unless it is pretty much certain the sitting president will lose the next general election. This last happened in 1968 when Vietnam was deeply unpopular in the Democratic party, and LBJ had approval numbers in the mid 30's.
Ford is another instructive exception. He had in fact never been elected (due to the unique situation of Watergate), and thus got a serious primary challenge from Reagan, which was not decided until the convention.
Answer: Why would they not be? In almost any election anywhere in the world currently doing the job is a massive advantage assuming that whatever you are supposed to be in charge of is not in the process of visibly self destructing.
You can claim credit for anything that's going right, blame anything that's going wrong on your opponents blocking your policy, or the previous incumbent leaving you a huge mess to clean up and travel anywhere in the country drumming up support, funds and doing rallies while passing the cost onto general taxation if you do some of the day job stuff while you are there.
Wikipedia has a nice overview, but there is an endless amount of stuff to read out there on the web. Including some with numbers on the US Senate and House races in 2018 from fivethirtyeight.
Primaries are essentially elections to find out who will be in the election. It makes sense that this Incumbent Advantage is magnified, as people are voting on whether they want to make use of the Incumbent Advantage.
Answer: The general political wisdom on matters like this is: "Don't bet against a winning horse." An incumbent has already won the election once, has a proven track record and national recognition, and has clout within his party that can sway people to support him. Worse, if a party wanted to abandon an incumbent and pick another candidate, they would need to provide an exceptionally good reason; people expect an incumbent to run again, and violating that expectation could shake faith in the party as a whole and cost the election in and of itself.
Normally this is a given, and the incumbent's party holds normal primaries and allows the incumbent to sweep the field naturally. The GOP has been restricting or cancelling primaries for the 2020 election because Trump is tremendously unpopular outside of his base, and while Trump would probably still win the primaries and be selected as candidate — that's the power of incumbency — the party is worried about infighting and giving the appearance of internal divisions. They do not want to give a voice to Trump opponents within the party.


Is it right to use compose of here

Question: For example,there are two kinds of human in the world, one is man, another is woman. Could I say that human is composed of men and women? Is it right to use compose of here? Or should I use include? Like this, Human include men and women. Thank you very much for any helps.
Comment: If there are only two of something, you have "one" and "the other". It doesn't make sense to say "another" if after "one" and "another" there's nothing else left to count.
Comment: What @Mixolydian said. There are some contexts where ***another*** can be used to refer to a second instance of something even if it's contextually certain there are only two altogether *(I'd rather be a kidney donor than a heart donor - at least you've got another in reserve!)*. But the sequence ***one is X, another is Y*** can only be used where there are known (or at least *believed*) to be more than two instances of whatever is being referenced.
Comment: ***the** other*, not *another*.
Comment: I think _another_ is also right here. _another_ is a pronoun. For example, 'It's a bill.' 'Oh no, not another!' . One meaning of _another_ is _different; a different person or thing_. If I was wrong, please explain why ^_^ @FumbleFingers Thank you very much!
Answer: You need to speak more generically when talking of humans. The two most common phrases/words are "the human race" and "humanity". Human is a countable noun, and even using "humans" would potentially imply each human is both male and female.

Humanity is composed of men and women.
The human race includes men and women.

Either of these would be fine.
Answer: "Composed of" is a good expression to use here. But please note the "d" at the end of "composed".
Also the word "human" can be an adjective ("We are all human."), or it can be a noun meaning an individual person. The word you need in your sentence is "humanity", which means "all human beings everywhere".
So your sentence should be:

"Humanity is composed of men and women."

Another way to say it is:

"Humanity includes men and women."

because "humanity" is singular. Either sentence is correct.

Is it right to use compose of here