How do blender units and meters, feet, or yards correlate?

Question: If I'm using blender game engine, how do blender units work in relation to gravity, acceleration, or weight?  Is there a rough physical world equivalent?
Comment: I think it's usually 1 BU = 1 meter with regards to physics simulations.
Comment: What do you mean by rough physical world equivalent. Units are used in the bge the same way they are used in the 3d view.
Comment: in relation to gravity, acceleration, or weight.
Comment: i think you need to keep an eye on the size of units when you go to 3D print especially, if not you will be trying to make something that does not fit the printer. a lot of difference whether you use metric or british when scaling things
this subject needs more explaining
Comment: @jmm I appreciate that you read multiple questions from me *probably* (the 3d printing and the blender units/real world thing).  They are separate though.  With 3d printing unit conversion would be arbitrary and would depend on the specificity required on the model.  This question was more concerned with physics simulations and how they interact with gravity.  I can add this to my question if you think it would be helpful.
Answer: Blender units
The Blender units system is a decimal unit system that can be whatever you want it to be. By default, it's implicitly considered meters. If you go to the scene tab in the properties panel, then to the gravity section, you can see that the rate of acceleration due to gravity is (0.000, 0.000, -9.810). 9.810 is the rate of acceleration in meters per second squared. So as you can see, it's implicitly considered meters. Now, if you change this value to -.0981 and every rigidbody's mass to 1⁄100 of what it was, you would now be working in centimeters and grams (or the cgs system).
Metric units
First off, let me start by defining a list of metric measurements that Blender uses.
Length

(km) kilometer [1000 meters]
(m) meter
(cm) centimeter [1⁄100 meter]
(mm) millimeters [1⁄1000 meter]
(µm) micrometers [1⁄100000000 meter]

Mass

(ton) metric ton [1000 kilograms]
(kg) kilogram
(g) gram [1⁄1000 kilogram]

If you go to the units section in the scene tab, you can see that there are three different options ("None, Metric, Imperial"). "None" is Blender units. If you select metric units, Blender will explicitly use metric units. Check back in the physics panel, and you'll now see (0m/s2, 0m/s2, -9.81m/s2).
For another example, select a mesh and hit n in the scene view to bring up the properties panel, go to the transform section and then dimensions. If you change one of the x, y, or z dimensions to a large number, you will see that it now uses the kilometers instead of meters. And if you change it to a ridiculously small number, like .000002, it will use micrometers.
Imperial units
Imperial units are the worst to work with. Also known as the British units. This is what backward America uses. Let me again define the units that Blender utilizes.
Length

(mi) mile [5280 feet]
(ft) foot [also symbolized with a single quote: ']
(in) inch [1⁄12 foot] [also symbolized with double quote: "]
thou or mil [1⁄12000 foot]

Mass (technically weight)

ton [2000 pounds]
(lb) pound
(oz) ounce [1⁄16 pound]

Separate units
If you are using metric or imperial units, you can use the 'separate units' checkbox which makes Blender separate out a unit of measurement into two separate units of measurement of the same system.
For example, without 'separate units' toggled, a field might display something like 2.538m. But with 'separate units' toggled, it would display 2m 53.8cm
Scripting
One thing you should note is that when working with scripts, and you use a function like bpy.ops.mesh.primitive_cube_add(location=(1.0, 1.5, 2.0)), which creates and positions a cube, the values are in Blender units even if you are working in metric or imperial. So this function, when using the imperial system, would place a cube at (3.281', 4.921', 6.562') or  (3' 3.37", 4' 11.1", 6' 6.74") with separate units.
Comment: That would be me. I fired up Blender and just learned all of this. Sorry.
Comment: Note that units are really useful only for sims. If you're creating a solar system, you'd maybe  say 1BU = 1000km. Blender uses internally floats, so you have only limited data range and precision to work with. Likewise, if you're working on microscopic scale, you could assume 1BU = 1mm for the same reason.
Comment: When you're using the weight units in the Imperial system, does Blender convert them into mass using the setting for gravity, or does it just assume standard Earth gravity for this calculation?
Comment: Can you add a credible link to the source of this information?
Comment: Aaand my answer is blown out of the water. +1!
Comment: @Gwenn exactly. It assumes standard earth gravity. Kind of how we weigh things in pounds to see how much mass it has.
Comment: @jesterKing precisely!
Comment: 1 µm is 1⁄1000000 meter, not  1⁄100000000
Comment: Uh, wouldn't the gravity be _more_ in the cgs system, not less? After all, it's the same value, but smaller units.
Answer: By default, 1 BU = 1 meter. Proof: the strength of gravity.

Earth's gravity is about 9.81 m/s2 (or 32 ft/s2, if you prefer) downwards.
Now, if you aren't using any physics simulations, 1 BU can be anything you like, and if you're using physics simulations, then you can tweak the strength of gravity anyway to match with the scale you've chosen.
Comment: @Gwenn: Probably because you're building all your models too big. For instance, the default cube is two meters long, wide, and high, which is a BIG cube.
Comment: But, in my experience, it has always seemed as though Blender's gravity has been too light. I always end up setting it to 20 or 30. This could be because I build all of my models too big though.
Comment: @Compro01. You need to assume that the time unit is second. It could also have been animation frames for example.
Comment: @user877329 - Not my answer.  I just fixed up some formatting on it.


Postdoc overwhelmed by incomplete work

Question: I take on more than I can handle and everything is left incomplete. Constant reminders from my previous supervisor, my current advisor, and colleagues, increases my anxiety level and sometimes I end up entirely avoiding work. I haven't completed a paper as first author in the last two years, although I have two papers ready for submission for the last two months and two more I could complete with a week of uninterrupted work on each paper. These papers have been dragged so much that now I am losing interest in making any more changes. I will appreciate any suggestion for dealing with anxiety regarding works that I should have completed more than a year ago.
Comment: I hope you find a great solution. This isn't just an Academia problem, this is a personal demon that you, and millions of others (myself included,) face on a daily basis. Many will say "just buckle down and do it" but that isn't how the brain works. You're doing the right thing, though - admitting you need help and seeking it! With a good support network you'll get through this =)
Comment: This sounds very familiar. But here's an important question. Are you working on these papers all by yourself? Because that clearly makes things much more difficult.
Comment: I am worried because this anonymous person who posted this s question hasn't interacted in anyway ever since. I can only hope all is fine and things clearing out.
Comment: Maybe you are too perfectionist. You don't want to release stuff which you arent 100% satisfied with. The problem is stuff can almost always be improved no matter how awesome they get...
Answer: This is a well known problem - and depending on your personal situation you should consider getting professional help by a psychologist. It's not a shame and it might prevent further harm. They could assist as well in creating a step-by-step program.
If you are willing to handle the situation by yourself, you'll have to do "a few" things (which are a lot to do!):

Learn to say "no" to specific tasks. Do not accept any new assignments unless your papers are done.
Figure out, why you are procrastinating - your mind has a reason for it and you should figure out what it is.
If the overall workload is too high, cancel some things forever. Eg. decide not to submit one of the "old" papers. How does this thought feel? Better or worse then the actual situation?
Go on step-by-step. Focus on finishing one of the old papers. Submit it. Take a break! Choose the next step of work.
If needed, be disruptive.

Take a longer break (e.g. 4 weeks of vacation)
Move your whole inbox to a subfolder "old" and never ever look at it - important mails will be re-sent.
...

If you are having a good relation with your supervisor(s), involve them in the process.
Comment: I think Point 3 is a very important one - I used to think it seemed obvious but only recently realised that (a) I wasn't following that point (b) by following it, some things actually improved
Comment: @Kaz - depends on your health insurance system - e.g. in Germany, it is covered by the common health insurance (at least to a certain extend). But of course a coach could do, too (but may be even more expensive). But a burn out or lifelong depression: $$$$$$$
Comment: Good advice. Learning to say no and establishing priorities  is a valuable learned skill.
Comment: professional psychologist: $$$  For that, you need a decent job with benefits.
Comment: @Kaz many schools in the United States have counseling departments for exactly this reason. It would be a good idea to visit one of these if one is present
Comment: #5 *move your whole inbox to a subfolder "old"* is definitely good advice. Personally I compulsively answer my emails immediately if I am free when I see them (probably not such a great thing), but an old colleague of mine had over 30,000 unread emails. Getting that crap out of your inbox, I can imagine, could be *huge* relief. And as you mentioned, if it was important, it will be resent.
Comment: Indeed, item #5B on email is huge. I just cleared mine out yesterday for the first time in 1.5 years, and yes, it was a huge relief! (Not exactly that technique, but I wrote it down in case I fall behind in the future.)
Comment: I have a *pending* folder. When I have emails sitting on my *inbox* for too long I just move them to *pending*. The oldest one I have there to "take care of maybe later this week" is from 2015.
Answer: I am trying to overcome the exact same situation. I am a 3rd timer postdoc. I believe the major cause behind postdocs quitting science relates with exactly what you describe. I am adding my general recommendations below, based on what I have been doing.
The root of the issue is at not being able to publish results between starting new projects. This is surely due to taking on more projects that one can handle, but I see this as also not getting enough support from collaborators. Thus I suggest you to concentrate on these two main problems. My advice as below:

Stop acquiring new data. I am sure you're are right worrying about some exciting new idea and results that could be scooped at just any minute by your peers. That you're itching to look into the details of something apparently groundbreaking you came across a few weeks ago. That you have 'supervisors' (people you grew to call 'bosses') trying to squeeze out more data and analyses out of your expertise. Just don't.
Take your time to list your unfinished projects, organise your files accordingly, backup all the raw data, and get notes in order in your computer. Back everything up as if you're ready to hand all of it to someone else to finish. This will help you line things up in your head and establish priorities.
Do not overwork yourself, and that is mainly mentally. Take at least one day completely off work, every week. Take vacations. During rest you must not think about any of this (have fun, hobbies, relationships). You must be able to forget in order to return to a task in any productive way.
Commit to a routine of exercise, stretching, meditation. Fulfilling tasks depend on good health, and a sane body. Understand you're making yourself sick. Whenever you feel heavy, go for a jog, take 30-60mins in some empty room for intense stretching, go trekking, swimming, whatever makes you feel empty again. This will help you sleep and heal.
Cold showers and waking up very early will wire your instincts back to physical awareness and make you feel stronger. This is too physiological to explain logically: just do it as if you're camping, and within few days you'll feel a big difference.
Focus on self-improvement and (implicitly and politely, but only if possible) tell your peers to bloody sod off. Too many professors nowadays will suck postdocs and PhD students dry, while sitting comfortably on a fixed income, pretending to be busy around empty/ghost meetings, random signatures, staring at some computer screen. They are just waiting. They are vultures waiting over you to offer papers and data for them to claim as their own. Do not dance for them. Almost any parasitic professor and collaborator is actually deadly scared of losing hosts, so as soon as you seem like dropping out, they'll give you space.

ONLY AFTER ALL OF THE ABOVE (should take few months):

Think of your savings, family situation, and alternative careers you could take up with your skills to decide on what to do next. Are you really sure you want to finish any of the projects you listed? Why do you want to finish them, objectively? Make a career choice here. My main advice at this point: make yourself ready to quit anytime. Having nothing to lose makes you ruthless.

(a) You want to finish some project(s). Focus on that one while following a strategy to finish it. Be selfish. Take your time, work only on this until it's finished. Do one single small step at a time, do not stop to look at the whole picture. This project must be personal, not for pleasing anyone or showing off. Contact your peers and demand help. If they are your co-authors they must help you with something according with your strategy. Should they refuse do get angry make it clear they are not legitimate partners on this. If you feel no-one is really helping and you're just dragging, kill this project and move on to the next one, or (b).
(b) You decided there is a better life for you elsewhere. Contact other postdocs and ask what they have in mind. Contact your friends and enlarge your interests network. Read a lot of books. Take a look into transitioning to other careers with your expertise, e.g. Industry, Coaching, Private Consulting, Teaching, Start-ups. Tell your peers you're moving out, and start negotiating whether they are interested in finishing projects using the data you organised. Wish them good luck.
You must keep in mind that you live for yourself. You do what you want. As a PhD you have skills which are highly sought for. The best way out of inertia and depression is through bold action. Do not worry about being gentle: take what you want and screw the rest.
You might appreciate reading this:
http://www.benchfly.com/blog/lessons-from-a-recovering-postdoc/
Comment: +1 for "make yourself ready to quit anytime. Having nothing to lose makes you ruthless." The importance of this is often underestimated in various endeavors.
Comment: I've seen "commit to a routine" suggested in a few answers and I wonder if other post-docs have experienced this: If I relax my productivity grinds to a halt. If I become regimented I can actually get work done (barely, and not healthily) but then I can't relax and stress out family/friends, particularly if normal life events disrupt my perfect schedule. So I opt for the latter because at least it means I'll be productive. I am also offered very few days for vacations so it's mostly out of the question. The rest of your points are spot on and very helpful.
Comment: @Scientist: "If they are really not helping, be ruthless and tell in their face they are out of this project". I like that idea in theory. In practice, implementation might be difficult.
Comment: @FaheemMitha It is only hard to implement when you're still trying to save it. Once you decide you're ready to quit, it's easier. 'Collaborators' are nobodies, unheard of out of the academia. And trust me: being bold creates silent allies & fans. Most people quit problems without making ruthless moves: that's leaving like a loser. A 1st step for reaching the best collaborators is getting rid of the bad ones. I for instance wouldn't want to collaborate with someone who has been publishing with scumbags -- you see? And in the end we know who are the scumbags. Do it and you'll feel great at least
Comment: @syntonicC With me the exercise and breaks routine works well. Because it means I will be fresh when I'm back to work. Sometimes I get really locked 'in the productivity zone' for long hours, and get a lot done but also feel like crap after and unwilling to work the next day. One could flip from the backlash. I think sustaining doing less for longer will get you to the end of project, instead of the end of willpower.
Comment: And my limited experience with "collaborators" is that they want to do as little as possible. It's possible I have not had the best collaborators, though.
Comment: Quick question, "Do not overwork yourself, and that is mainly mentally. Take at least one day completely off work, every week.", I am wondering if this means not doing cognitive demanding tasks or not doing tasks related to your work? For example, in my spare time I like to learn or relearn mathematics. Is it best to stay away from that on the "day off" in order to perform optimally on the other six days?
Comment: @ThomasKing Hi, I am no specialist on this but from my experience the time-off period restores your focus by distracting your mind to other tasks, and by releasing endorphins which keep stress at bay. So I believe that will depend on how much effort and endorphins you take in studying maths. For most people exercise, contact with nature and intimate relationships are the most intensely de-stressing activities -- if you can somehow couple maths into those I believe you'd hit the best results.
Comment: "but I see this as also not getting enough support from collaborators". No kidding. But would "not enough" perhaps translate to "almost none"?
Comment: @FaheemMitha That's hard to infer from this case. Sometimes collaborators are helping or willing to help (i.e. technically) but the first author won't ask or accept it, or is just psychologically stuck. Still, asking for more help won't hurt them -- what are co-authors for? If they are really not helping, be ruthless and tell in their face they are out of this project.
Answer: Thanks for posting this question. I'm a postdoc who ended up in a very similar situation as you have. At some point, it caught up to me, I had a mini breakdown, ended up with a short hospitalisation followed by anxiety that was intense enough that some days I was afraid to leave the house. I'll tell you what helped me, both in terms of changes in my personal and professional life.

Find support. You hopefully have friends, family, or coworkers in your life with whom you can share what you are going through. You might feel embarrassed or awkward about sharing this very personal part of your life. This is normal, but try your best to proceed anyway. I once found myself so tense I didn't know what to do with myself. I reached out to a friend despite my every inclination telling me to just deal with it. The feeling of relief that came just from making the decision to talk to someone was so intense I cried for 10 minutes and then slept for an hour.
Find professional support. This is step 2 because it's harder than step 1, and can be hard to find someone with whom you work well. For myself, the key was finding more body/mindfulness-based therapy, but traditional talk therapy can be great to. Depends on you and your therapist.
Make time for yourself. For me, I found taking 5-60 minutes per day (busy academic schedule, eh? what can I say, it's the effort that counts) to be calm and quiet worked wonders. I found some resources for incorporating yoga and breath meditation into anxiety treatment, and these were very effective more me. For others, more physical exercise does it. Be open minded, willing to experiment, and find what works for you. Making sleep a priority was also key.
If it helps you, take a break (short or long). But don't force it. I found a longer break when I wasn't ready made it worse. I suddenly had no structure, and that just made me more anxious. But a day off to go the mountains when things got to be too much was perfect medicine.
At work, take things a step at a time. Don't worry about the paper you have to write. Focus on the paragraph you have to write. On the one analysis you are going to do before lunch. One the small and concrete steps that get you where you need to be. The big picture will come together. If things don't proceed as fast as you like, be kind to yourself, and let go of the expectation that it should have been faster. As others have noted, take regular breaks. I work for 30, then walk for 5.
Seek affection (if you are someone who is comforted by this). If you are lucky enough to have someone (human, animal, whatever) in your life who gives hugs on request, take advantage of it. It sounds corny, but seriously, it's helps a lot more than we give it credit.
Finally, accept that it's just a job. Whether you know it or not, you have other options, and even if the career train you are on doesn't work out, you will be ok. Your life and your mental health are more important than the career.

Take care of yourself, and I wish you luck on your journey.
Answer: Get help. Speak to a psychologist, it will never get better on its own.
I have ADHD and Asperger's and I identify with your problem. I get the usual rush that you get starting something new or trying a new sport or activity as your body responds to the new and exciting activity but my body just does not generate the same response that other people have after the rush period is over and the satisfaction response starts.
As a result I start loads of things but never finish as my motivation goes. My average life of a hobby is just under 6 months and my attic is full of gear from abandoned sports and games.
After getting help I now have a rigid structure that allows me to complete my tasks. My personal structure is a half hour work period, 10 minute break and another half hour on a different project. The switching helps me to avoid boredom and finish tasks. I also have rigid planning and defined goals to stop me meandering off topic.
This is tailored to me, you will need to find out what works for you but you WILL find something that works with the help of an expert.
See an expert now and things will improve.
Comment: Is there a specific type of psychologist which helps with this sort of thing?
Answer: I can very much relate to your problem. However, I have learned to handle this problem (although it took me some time), and I believe that you can learn that too. Now, I don't know how much you avoid the work. I took it to the extreme, and avoided work for long periods of time. So my advice/comments focus a lot on that.

I saw a psychologist once a week, which really did help.
For me, the most important part was to learn how to accept the presence of anxiety and not respond to it by avoiding whatever it is was that made my anxiety levels rise. Anxiety is a feeling, but avoiding something is an action, i.e. they belong to two completely different categories. It is possible to learn to immediately respond to increasing anxiety levels by acting and confronting rather than avoiding. The old way of responding for me was to try and distract myself by doing or thinking about something else. My new way of responding is to ask myself: What will happen to my anxiety levels if I sit down and work for four hours with a ten minute break each hour? Then I "experiment" by doing just that, and I always write down the results (that is, what actually did happen to my anxiety levels). Sometimes the anxiety persists, but often I forget about it once an hour or so has passed.
I noticed that things started to change when I started to open up to people. For me, avoiding work made me feel ashamed of myself. And unfortunately, I had a person in my life who told me that I was avoiding work because I was lazy, which made me feel even more ashamed, and I didn't trust that there could be people in my life that would understand and support me. But eventually I did open up to my parents and to my supervisor, and they were very supportive. Not everyone will be, but some people will be, and those are the people you should talk and listen to.
Take the evenings off. Because I was worried that I was in fact simply a lazy and worthless person, I didn't think I deserved evenings off. I was behind on my schedule, and it seemed strange to me to allow myself to relax in the evenings while that was the case. But I know now that if I want to function normally, I must take care of myself.
This point is related to the previous point. I don't know about you, but I had a tendency to think that I had to "catch up" with the time I had waisted on avoiding work. So I would make plans that were impossible for me to follow and finish. The thing is, if you haven't been able to work 8 hour days lately, you won't suddenly be able to work 13 hour days starting tomorrow.
Write a list (or several) of what needs to be done. Don't give yourself deadlines, instead give yourself hours that you should be working. Start at the top of the list, and move on to the next point once the previous has been completed. Giving yourself a deadline puts pressure on you, but I don't think that more pressure is what you need. Sometimes you might feel the need to move on to the next point on the list even though you aren't finished with the previous one. Sometimes, that is necessary and justified, other times you are just avoiding something that gives you anxiety, or are simply too unfocused to stay with the task that you've given yourself. You need to be honest with yourself: Why do I want to move on to the next point despite not having completed the point I am currently on? If the reason is anxiety, then fight that urge.

Lastly, good luck. It might seem impossible right now, but these things can change quickly. Once you have managed to complete some of the work that is currently incomplete, you will already notice a big change in motivation and how you approach your work.
Comment: In most lines of non-menial work no-one can realistically take advantage of the full 8 work hours; you will be happier once you realize that is normal.
Comment: Very insightful advice!
Answer: There are many great answers above, mine is just an addition and not an alternative answer.
I face similar problems and what helps sometimes is to classify work to:
<code>----------------------------------------------------------
|            |     Important     |     Not Important     |
----------------------------------------------------------
|   Urgent   |         A         |           B           |
----------------------------------------------------------
| Not Urgent |         C         |           D           |
----------------------------------------------------------
</code>
Classify your tasks into A,B,C, and D.
Priority is given to tasks under A, there are no disputes about this.
But then actually we are often tempted to look into the tasks under B. But what you want to do after you are done with A tasks, is to focus on the tasks under C before they find their way to A.
For example, as a final year PhD student, conference deadlines fall under B, while a PhD dissertation falls under C.
Comment: If you don't work on C most of the time, everything will become A at some point. Thus, priority should actually be on C.
Comment: @henning eh? There are two points to this approach: the first is to recognise that Cs become As, the second is that if you don't work on Bs or Ds, they eventually go away without anything particularly bad happening. (This is often called the Eisenhower method, by the way, after a quote attributed to Dwight D. Eisenhower: "I have two kinds of problems, the urgent and the important. The urgent are not important, and the important are never urgent.")
Comment: Given that OP says they are a postdoc, I think their PhD dissertation definitely falls under "A" by now :)
Comment: @arboviral I meant it as an example. For a post doc, it could be a professorship application, a grant, etc..

I like the quote. Ideally we would never allow ourselves to have A tasks i.e., we get done with them while they are still in C, before they move to A.
Comment: The second comment was meant in jest, of course. Although technically I didn't submit my thesis until four months after I started my 'postdoc' - they paid me as a research assistant until the viva then backdated the pay difference, which was nice.
Answer: I've had the same problem all my professional life. The only solution that worked for me thus far was to make a list of the stuff to do, and start doing the most urgent research task, while putting off everything else.
Right now, I have to worry about a project starting, an ongoing one and a grant I plan to apply for. I also have a paper to finish. I decided to put the paper at the top of my list and 80% of my efforts every day go into completing that paper. I don't do any other serious work right now, and I reject any other task until that paper is done.
I removed from my work environment anything reminding me of the other research stuff unrelated to the paper. I blocked SE on my computer at work and everything else that could distract me from the writing. When I'll finish with the paper, or get seriously stuck, I will go to the next research task in my list.
Answer: A few comments on the the fly, hoping they help. Hope and help are key words, indeed.

Take care of yourself: by the way, try make a conscious, but not stubborn, effort of defining to your mind who the 'yourself' needing care is;
For many organizational problems, a commutative rule applies: the order in which you solve them does not matter. It doesn't matter if you publish the second paper first, or the third paper second, and so forth. Go for the most ready or inviting ones: low-hanging fruits first. These tips break the analysis-paralysis situation;
You are already asking for help in this forum. I see valid and compassionate answers here. You are already being helped out, it's on you to weight those reactions and proceed (at your own risk, naturally, but in no solitude);
Pause, revise, reverse where needed. You are already able to describe your distress, which is key. You did pause. If you don't know whether the bottle is half-empty or half-full, turn the question into what you should do with that bottle: staring at it, filling it, drinking it, emptying it, throwing it away, changing focus of attention altogether, collect more bottles, ...
Be accepting of your weakness. Strength is most frequently developed in steps and through training (at least, leaning on what physical exercise teaches us). You might have been lazy on the first signs, map back what happened this far. The tale of Little Thumb is profound there: he's smart because he keeps tracks of his path into the dark wood using breadcrumbs (a term now also used with the most confusing of experiences: Internet surfing);
Unless it is organization what you deeply hate and hurts your true self, consider evaluating your intents according to the SMART criteria (many others may be a better fit to your personal situations).
Answer: I suggest using Scrum and Agile techniques to plan and organize your work before actually tackling it. If you can setup a kanban board of tasks for each project, and try to break down tasks into something you can accomplish in less than a day, then it will visually show you progress toward your goal. For me visual progress is one of the keys to motivation.
Answer:
I have two papers ready for submission for the last two months and two
  more I could complete with a week of uninterrupted work on each paper.

Pareto rule: The last 20 percent take 80 percent of the time. Leave some work for the reviewers! If you can't let go, you can still polish and edit after you've submitted your draft. It will be a draft, because there is no such thing as "finished" in academic writing. In the words of Tara Gray:
Kick it out the door and make them say "No"
Feel the relief. Then move on to the next project. Only look back once you've gotten the reviews; then work them into the draft and submit to the next journal.
At this point, you don't have to target A+ venues. A finished B publication is better than a non-finished A publication.
Answer: Although a psychologist should help you with the emotional part of the problem, I think you should get a coach to help you create a plan and stick to it until you objectives are accomplished. It is a more pragmatic way to solve the productivity part of the problem.

Postdoc overwhelmed by incomplete work


Why is $\Delta x \Delta k \approx 1$ in any pulse?

Question: In my physics textbook, it says that for any pulse, if $\Delta x$ becomes smaller, $\Delta k$ becomes larger where $k$ refers to $2\pi/\lambda$ and $x$ is x-axis displacement, as described by $\Delta x \Delta k \approx 1$. Why is it like this?
Answer: It's not clear whether you mean a pulse of a wave, i.e. a short section of a wave, or whether you mean a top hat function, but in both cases the principle is the same.
If you Fourier transform a pulse of a wave or a top hat function you get the frequencies that make it up. If you decrease the length of the pulse or reduce the width of the top hat function you'll find that the width of your Fourier transform increases i.e. it spreads across more frequencies. That means it's harder and harder to pin down what you mean by the frequency of the pulse. In the limit of reducing your pulse to a delta function you find the Fourier transform now inludes all frequencies from zero to infinity at an equal amplitude so it's impossible to define even an average frequency.
This is the sense in which $\Delta k$ becomes larger. In real life we often find the Fourier transform is approximately gaussian and we can define $\Delta k$ as the 1/e half width (i.e. the standard deviation).
Answer: To add a little to John Rennie's answer--- it is only true for pulses that are smooth and qualitatively resemble Gaussians, for which the root mean square widths of the pulses are related by the exact relation:
$$ \Delta x \Delta k = {1\over 2}$$
If you make a sum of separated delta function pulses, you can make both $\Delta X$ and $\Delta k$ big. For example, taking a signal which is two delta functions at $x=\pm a$, the Fourier transform is a sum of two sinusoids which are nonzero over all space, so $\Delta k$ and $\Delta x$ can both be large.
If you make a non-smooth pulse, you can have large tails on the k-distribution. For example, the Fourier transform of $e^{-|x|}$ pulse is ${1\over k^2+1}$, which has an infinite second moment, so is infinitely broad in k (but not infinitely sharp in x).


When did cheese enter the Korean diet?

Question: The local Korean deli uses cheese in many of their dishes; my friends from several other East Asian countries have commented that they still consider cheese to be unusual and not part of their normal diet.  It is entirely possible that this is a sampling error, but I'm curious when cheese entered the Korean diet. (I did some google searching, but the results about modern Korean diet overwhelm the historical sources, and the historical sources don't refer to cheese at all.)
Comment: Note that "oriental food" served in the West is quite "Westernized" in both recipes and base materials. I have seen several documentaries about chinese food and it is quite different from what you would usually see at your local restaurant.
Comment: Something like 90% of the population of Korea is lactose-intolerant: http://www.moofreechocolates.com/wiki/global-lactose-intolerance-statistics (This statistic may be based on a low threshold for defining what is lactose-intolerance, e.g., they say 20% of French people are lactose-intolerant, but I think virtually 100% of the French eat cheese.) I live in a neighborhood in the US that is majority Korean, and we have a lot of Korean restaurants, supermarkets, and bakeries. I have seen very little dairy in these places. The bakeries do sell things like cream-filled pastries.
Comment: @BenCrowell most individuals who are lactose intolerant can handle small servings without ill effect (for example, 1 glass of milk per day). Lactose intolerance isn't going to affect the uptake of dairy in cuisine because it is so mild.
Comment: This question is a bit akin to asking "When did kimchi enter the Western diet?" Just because cheese (kimchi) is today sometimes consumed by some Koreans (Westerners), doesn't mean it's a regular part of the Korean  (Western) diet. Probably more Koreans eat cheese than Westerners eat kimchi, but that is more probably due to Western culture being more dominant than the Korean one. Maybe 500 years ago the first Korean (Westerner) had the first taste of cheese (kimchi), but I don't think that's what you're looking for.
Comment: @congusbongus tell that to my sister who gets violently ill for days consuming something that's been prepared in a frying pan that has previously had butter in it and hasn't been very thoroughly cleaned...
Answer: 1959, by a Belgian missionary named Ji Junghwan, who helped started domestic Korean cheese production at Imsil County.

Cheese was introduced to South Korea in 1959 by a Belgian missionary, who came to Jeollabuk-do to help people surviving the Korean War.
 Lee, Cecilia Hae-Jin. "Keolla Do" Frommer's South Korea. 2nd ed. Vol. 775. Hoboken, NJ: Wiley, 2008. 19.
It was out of youthful ardor that he chose to be a missionary in Korea right after the war ... Ordained a priest in 1958, he arrived a the Diocese of Jeonju in 1959 and soon took on quite a few big adventures ... when he was appointed to Imsil he raised mountain goats and started to make cheese.
 - The Korea Foundation, "Korea Focus - September 2012".

This marked the appearance of cheese in the Korean diet. Cheese is not a component in conventional Korean cooking, however, and consumption thereof remained (and in relative terms, continues to be) light for decades. As late as 1990, total cheese consumption was only 7,000[1] tonnes - around 20 grams per person.
Korean appetite for cheese has since experienced tremendous growth, driven particularly by the adoption of western style food such as pizzas. Nonetheless, as late as 2013, the South Korean per capita consumption of Cheese was only 2.2kg[2]. For comparison, the average American consumed 15.7kg[2] of cheese in the same year.
Sources:

Canadian Dairy Information Centre
Dutch Ministry of Economic Affairs

When did cheese enter the Korean diet?


Half note and quarter notes that use the same stem?

Question:
Why is there a half note and quarter notes that use the same stem? How to play it on a violin? and What's it called? Thank you.
Comment: such notation sometimes is the out put of a notation program. It would be interesting to know the context,  where this sheet  music comes from ...
Comment: It's clear to violinists!
Comment: Do you have a more zoomed out picture? My initial reaction is that it's written incorrectly but it's hard to tell without a bigger context
Comment: @nivlac this is the best resolution within 2 mb limit..
Comment: He wasn't asking for higher resolution, just a picture of MORE of the score.
Comment: It's a bit naughty writing like this. could be a lot clearer.
Answer: You've tagged the question 'violin'.   So I guess this is violin music.
Think of the mechanics of a violin, the way the strings are supported by the curved top of the bridge.  Mostly, the player wants to bow just one string without touching the others, the curvature enables this.  He can bow two strings at once if he wishes.  But not three.
This notation asks for the common gesture where the lower notes are played briefly and left to ring, the upper note is then played normally.
(For the sake of completeness, I should mention that fully bowed triple stops CAN be achieved in certain circumstances.)
Comment: it's from symphony no. 8 from Mahler this appear in both Violin 1 and violin 2 parts
Comment: I printed from the website that said to be **Original**, I don't know
Comment: Laurence is right. There are similar  notations in several sections (fifth and tenth intervals)
Answer:
Why is there a half note and quarter notes that use the same stem?

The composer wants you to come as close as possible to playing three notes at the same time.

What's it called?

It is called a "chord" because there are more than two notes. Two notes played simultaneously would be called a "double stop".

How to play it on a violin?

The two quarter notes are A and E which conveniently you can play as the two adjacent open strings. The half note is a C which you would play as a third finger in third position on the E string so that at the end you can put down your first finger on the E to play the slurred A.
To play this you would start with your bow on both the A and E strings playing the A and the E as a double stop, then put your third finger down so you are playing the A and the C as a double stop, then adjust the angle of the bow slightly to come off the A string and complete on just the C on the E string.


Is it a coincidence that both the Sun and the Moon look of same size from the Earth?

Question: The Sun is huge, when compared to the Moon. Despite the huge difference in their size and distance from Earth, is it purely coincidental that they both look almost the same from Earth?
Comment: It's a sheer coincidence that at this point in time, just when humans have modern society, they are identical.  Of course, it's a staple of sci-fi plots, and conspiracy theories, that since it is such a ridiculously amazing coincidence they happen to be identical, this must have something to do with a message from aliens, higher beings, or similar!  It is a totally outlandish coincidence, whatever you think of it!
Comment: Better question might be - is there any *consequence* related to similar apparent sizes, aesthetics aside.
Answer: The coincidence isn't so much that they appear very similar sizes from Earth, but that we are alive to see them at the point in time in which they appear very similar sizes.  The moon is slowly moving away from the Earth, and at some point in the future the moon will be unable to totally eclipse the sun and conversely, if you could step far into prehistory, you would be able to see the moon with a much greater angular diameter than you see it now.
Most research I've found on the topic seem to be unavailable through my institute, however I did find one paper, "Outcomes of tidal evolution", which references results from Goldreich's research on the subject.

This qualitative description of the eventual disruption of the Earth-Moon system is confirmed by the results of Goldreich's numerical integration, which showed that the moon will recede to 75 Earth radii, when spin-orbit synchronism will be reached; then the Moon's orbit will decay steadily inward because of the influence of the Sun.

For reference, the Moon is currently at a distance of approximately 60.3 Earth radii.  As such, the moon will steadily move away until synchronism would be reached, and from that point begin to recede towards the Earth due to the tidal affects of the Sun on the Earth disturbing the synchronization. It would seem that at some eventual point in the far distant future, it will return to this coincidental position once again.

Counselman III, Charles C. "Outcomes of tidal evolution." The Astrophysical Journal 180 (1973): 307-316.
Comment: This refers to [tidal locking](http://en.wikipedia.org/wiki/Tidal_locking) between two bodies. In this case, reaching a point where the Earth and Moon are tidally locked.  This is important, as the mechanism for the Moon moving away from the Earth is due to the tidal forces of unsynchronized movement between the two.  As they reach synchronization the distance _would_ stabilize, if not for the additional tidal forces from the Sun destabilizing the system.
Comment: The Moon's rotation is already synchronized to its orbit. In the distant future, the Earth's rotation will also synchronize to the Moon's orbit, so the Moon will be visible only from one hemisphere and a day will be a month long (and a month will be even longer than it is now). Pluto and Charon are mutually locked in this way.
Comment: What do they mean by "spin-orbit synchronism"?
Comment: Moon size changes visibly over time: Micro Moon over Super Moon  http://apod.nasa.gov/apod/ap140121.html This is why we see annular solar eclipses sometimes: http://en.wikipedia.org/wiki/Solar_eclipse#Types
Answer: I'd argue it isn't a total coincidence, but it isn't artificial either.
Out of possible arrangements allowing for stable orbits, what positions of the moon on the Sun-Moon-Earth line offer near equal angular measures?
Let:
$$l_s=150*10^6 km=1AU$$
$$r_s=695,508km$$
$$r_m=1,737km$$
$$l_m=384,400km$$
Where $l_s$ is distance from earth to the sun, $r_s$ is radius of the sun, $r_m$ is radius of moon. $l_m$ is distance from earth to moon, hear assumed to be along the straight line running from earth to sun. $l_m$ will be variable, but empirically on average has the value given above.
For what values of $l_m$ does $r_m/l_m$ , the tangent of the angular radius of the moon, fall within 10% of $r_s/l_s$, the tangent of the angular radius of the sun? i.e.:
$$(0.9)(r_s/l_s)<(r_m/l_m)<(1.1)(r_s/l_s)$$
$$0<\Delta(r_m/l_m)<(0.2)(r_s/l_s)$$
$$0<\frac{r_m}{l_m^2}\Delta l_m<(0.2)(r_s/l_s)$$
$$0<\Delta l_m<(0.2)\frac{r_sl_m^2}{(r_ml_s)}$$
So if $(r_m/l_m\approx r_s/l_s)$, then $l_m$ can vary by $20\%$  of its current value and still maintain an approximately equal angular radius- a Goldilock's Zone.
There are a few back of the envelope methods to gauge how far the moon can get from earth to remain in a stable orbit.
How far can the moon get without escaping from the earth? The Hill Sphere (h/t uhoh!)of the Earth has a radius of about $(0.01)l_s$. Further away from there and the sun perturbs the moon away from earth, establishing a maximum distance for our allowable range. The Roche Limit is a lower bound.
Whereas the probability of the angular radii being about equal if allowing the moon to be any place on the straight line joining the earth and the moon is approximately $\frac{(0.2)l_m}{l_s}=0.051253\%$, factoring in that the moon can only be just so far from the earth without decoupling, that probability goes up to at least $\frac{(20.0)l_m}{l_s}=5.1253\%$ by the above arguments.
A more thorough approach uses tighter bounds. There's a Goldilock's Zone for the moon and sun to have the same angular radius. The probability of falling within that Goldilock's Zone is the ratio of the Goldilock's Zone $(0.2l_m)$ to the interval  between the minimum and maximum distances from the earth to the moon factoring in orbital stability, the moon's recession,  and eventual return closer to earth. From answer above, the moon is 60.3 Earth Radii from Earth and will not get further away than 75 Earth Radii. The Goldilock's Zone spans from about 38 Earth Radii to about 72 earth radii.  So between now and maximum recession of the moon, and assuming uniform time spent at each distance, the angular radii will match to within 10%  about 75% of the time.
Overall its a low probability that the angular radii match so well. Given the distance the Earth lies from the sun and the radius of the moon which are fairly arbitrary, gravity allows the above mentioned Goldilock's Zone to have significant overlap with realistic lunar trajectories.
Put another way, if the Equal Angular Goldilock's Zone has sufficient overlap with allowable lunar orbits, then the angular match becomes about as likely as having a moon in the first place which itself is a coincidence.
Comment: It would be a good idea to calculate the size of the [Hill sphere](https://en.wikipedia.org/wiki/Hill_sphere)  (also [here](https://space.stackexchange.com/a/26035/12102)) around the Earth, outside of which gravitational effects from the Sun (rather than Venus) will have an effect. I don't know if that's required using your approach, but I think you should rule it in or out.
Comment: Thanks @uhoh! Is required. I'll patch it up manana.


How to Forward Port 22 to allow SSHing from outside LAN

Question:
Possible Duplicate:
What is port forwarding and what is it used for?

I want to be able to SSH my computer from anywhere. I heard I have to forward port 22. I honestly have no idea what that means or how to do it. Can someone help me?
I'm on a mac!
Answer: This is quite a straightforward operation and the principles of port forwarding (or where to find the info) have been pointed out by others, but just a few more tips:
1) Port forwarding is a feature of your 'outside world' connection device - maybe a cable or ADSL (broadband) router so you'll need to check its docs - probably it has a Web interface for configuring this.
2) Every man and their dog knows that the ssh port is number 22, so if this port is open to the outside world, you will get a lot of attention from elsewhere trying to login using user/password tables etc. To help with this, see if your router supports forwarding alternate ports so, for example, you can instruct it to forward (say) external port 40822 to your computer's port 22 and then you would ssh connect to port 40822.
3) In the long run, if you are going to access your computer regularly from the outside world, you should read up about setting up OpenVPN (or another VPN system compatible with your OS) to give you a secure tunnel into your machine.
Answer: Your home internet connection will be handled by an ADSL router or a Cable router or something similar.  When people talk about port forwarding in the context you're referring to they usually refer to the firewall / NAT section of your home router / modem.
If you want to be able to SSH into your machine at home, you have to tell your home router / modem to accept data on port 22 and send it to a specific computer on your network (your PC).
This site has some very annoying adverts, but also, a lot of guides for port forwarding by router version which since you didn't tell us what you have, is probably a good place to start.
Additionally, you don't tell us what OS your PC is using, but you'll need to ensure the firewall on your PC allows incoming connections on port 22 (whether that's iptables on Linux or Windows Firewall, or whatever else you're running).


What happens to an Oracle sequence after disaster recovery?

Question: Suppose an Oracle instance has to be recovered after a disaster.  Do sequences get reset to the initial state, or the last saved state, or are cached values preserved?
Thank you very much. :-)
Answer: The sequnce values are stored in the SYSTEM.SEQ$ (I think) table, and a cache is maintained in memory of the next values to be used, with the size of that cache being dependent on the CACHE value for the sequence.
When the cache is exhausted the SEQ$ table is updated to a new value (in a non-consistent manner -- ie. without the user session's transacton control applying) and the next say 100 values (if CACHE=100) are read from memory.
Let's suppose that you're using a sequence with a cache size of 20. When you select a certain value from the sequence, say 1400, the SEQ$ table is updated to a value of 1420. Even if you rollback your transaction the SEQ$ still has that value until the next 20 sequence values have been used, at which time SEQ$ gets updated to 1440. If you have then just used value 1423 and an instance crash occurs, then when the system restarts the next value to be read from the sequnce will be 1440.
So, yes the integrity of the sequence will be preserved and numbers will not be "reissued". Note that the same applies to a graceful shutdown -- when you restart you will get a new value of 1440 in the above example. Sequences are not guaranteed to be gap free in practice for this reason (also because using a value and then rolling back does not restore that value to the cache).
Answer: Not that I have any experience with this, but I very much assume that a recovery to a consistent system change number state would also return the sequence to the last saved state. Anything else would be fairly useless in terms of recovery.
As for cached values, those are (can be) lost even when the instance shuts downs in an orderly manner (*): Instances cache a number of sequence values in memory (SGA) instead of going to the database every time. Unused sequence values that the instance has reserved can "disappear", leaving you with gaps in the sequence.
(*) 8i documentation mentions that this can happen with parallel instances (RAC), in which case the sequence may not even be strictly ascending (but still unique), 10g docs say that it happens in case of an instance failure.


What's Goku's and Vegeta's green aura in Dragon Ball Super Broly?

Question: In Dragon Ball Super Broly, both Goku and Vegeta displayed a green aura for a couple of seconds. Vegeta did it when he switched from super saiyan to super saiyan god, and Goku did it when he switched from super saiyan god to super saiyan blue (Goku also displayed a white mastered ultra instinct aura for a couple of seconds too). What does this mean? What's Goku's and Vegeta's green aura in Dragon Ball Super Broly?
Answer: There are a lot of fan theories claiming that Vegeta's green hair transformation was possibly foreshadowing a new form as we also see Goku display a transformation similar to Mastered Ultra Instinct while transforming to Super Saiyan Blue. However, there aren't any statements or actual facts from the writers, Toriyama or anyone related to the movie. Hence, I think it is fair to assume that these are just animation choices from the animators to simply make the transformation sequences more dramatic.Evidence to support this is Goku's transformation to Super Saiyan Blue. We have seen Goku effortlessly tap into the form so many times. However, he has a very dramatic transformation sequence when he taps into Super Saiyan Blue to fight Broly.Note: This is my personal opinion and it might not necessarily be true. I believe the animations were done on purpose to indicate some form of similarity in the Super Saiyan transformations between Goku/ Vegeta and Broly, mainly for the new fans who are unaware of the franchise.
Answer: I believe based on what I seen from the movie. While Goku was in super saiyan god, and fighting with Broly his eyes blanked out ( turning white) same as broly's final form. So that would bring a new transformation for both Vegeta and Goku. The only differences will be Goku transformation will be stronger for the simple fact of his base form and his power-ups, they'll mostly be similar transformations.
Answer: I believe it was the choice of color for some of the scenes, such as Goku's transformation into Super Saiyan Blue, some of the colors may have mixed to make green. Vegeta's hair could have been a color choice by the people behind the movie.
Regarding Mastered Ultra Instinct, I think we actually saw it. Goku May have triggered it in complete accident, due to the fact he was almost just beat to death and was desperately trying to reach Super Saiyan Blue. He may have broke his shell like in the TOP and tapped into Ultra Instinct for a few moments.
Hope this helps.
Answer: I think that that just how Broly has a state in which his aura his eyes became green. Although he does not goes to ssj. His father had said that he had reached the state in which he uses the power of Ozaru even in his normal form.
Goku and Vegeta may had reached the state for few seconds while fighting Broly. This is only a theory which is not mine, a Youtuber named Negus Sayain uploaded a video in which he said this theory.
Answer: Just an animation choice, a call back the original Broly film where there were scenes where character had different hair color. Don't read to much into it.
Comment: Can you elaborate and add sources to validate your claim? 'One-line' answers are heavily discouraged, unless it addresses all the OP needs to know, including evidences.


How do I neutralize melter honey?

Question: I was wondering how to neutralize melter honey into more of a straight sugar base and get the acid levels down.
Answer: Melter honey is melted and extracted from the caps of the honey comb. The prolonged heating can caramelize the sugars a bit and darken the honey.
Although it may reduce a little, I'm not able to find any resource that says that it reduces enough to become significantly more acidic than regular honey.
Regular honey can be neutralized for cooking by adding 1/2 tsp of baking soda for every cup of honey that is used. I think this ratio would also be appropriate for melter honey.

How do I neutralize melter honey?


Does the Higgs field really explain mass or just reformulate it? What about charge?

Question:
The mass of a particle used to be considered a fundamental and intrinsic property of the particle; on the same level as other properties such as charge, spin, chirality/helicity. Due to the Higgs mechanism this has changed. The mass is now considered a property that is acquired as the result of interaction with the Higgs field. But why is this so relevant? Instead of an intrinsic mass, now each particle type has an intrinsic coupling constant which describes the strength of its interaction with the Higgs field. It seems to me that, as long as we have zero knowledge about the nature of this interaction and hence about its strength, the problem of mass has merely been reformulated into something equally mysterious.
I suppose it may be of interest to propose a coupling of elementary particles to some background field that permeates the universe. One key question is then how this field strength can remain perfectly homogeneous in space and times. If no ripples are allowed, then there are no sources and sinks for the Higgs field. But how can it interact with matter, without being influenced by the very same interaction? This seems paradoxical to me.
Is there a particular reason why one can't propose a "Charge field", which is a quantum field that interacts with certain particles and thus gives them their Charge?
Comment: For future reference, @M.Wind, it would have been better to post each of these three questions separately.
Comment: This link might help  http://profmattstrassler.com/articles-and-posts/particle-physics-basics/how-the-higgs-field-works-with-math/2-why-the-higgs-field-is-non-zero-on-average/
Comment: Related: http://physics.stackexchange.com/q/31247/2451 and links therein.
Answer:
An obvious difference between the two ways of thinking about it you mention is that in the case of the Higgs mechanism, there is an observable particle excitation of the field associated with it, which was found recently. Furthermore it should be noted that the Higgs mechanism only concerns the mass generation of some elementary particles. The mass of composite particles like hadrons is largely due to strong interactions, which are not related to the Higgs.
The idea of fields spanning the universe is not unique to the Higgs field. It is the principle that underlies quantum field theory which describes all particles of the standard model. I suggest that you acquire some profound knowledge on the subject in books by Zee or Srednicki.
The reason that mass is generated by the Higgs field can be traced back to the spontaneous breaking of a symmetry. There is no such symmetry that might explain the generation of charge in a similar way.
Comment: There is nothing unknown, elusive or even mysterious about the Higgs field and its particle excitation, the Higgs boson, that was discovered at LHC (at least not at the level we're having this discussion at). Your reference to the "majority of physicists" is devoid of any factual evidence. If the majority of physicist was of a different opinion, there would not have been a Nobel prize awarded for the Higgs mechanism.
Comment: @M.Wind the fact remains that fields have dynamical properties, whereas 'fundamental masses' do not. Even if you don't think that the Higgs was found (why??) the fact remains that such an excitation *would exist*, which makes it a distinct and testable theory, not just a mathematical reformulation of the same physical content. It should also be noted that mass and charge are in no way analogous. Mass is fundamentally about energy, and only some mass (a small amount in many circumstances) arises from the Higgs mechanism.
Comment: 1. The fact that some unknown particle was observed at a certain energy in an accelerator experiment, is (for the majority of physicists) not the most convincing evidence for a new elusive field that permeates the universe.
Comment: 2. Our universe is expanding. Vast regions of empty space are being created every moment. It remains to be seen whether a vacuum filled with a range of quantum fields (such as Higgs) has a zero energy density. I think many physicists have concerns about the energy implications regarding grand ideas like the Higgs field.
Comment: Regarding your statement about energy density: please rephrase it, it makes no sense. There is no reason to assume that the energy density of the vacuum is zero, and this has got nothing to do with the expansion of space.
Comment: Furthermore, and not meant as an offense, I would not dare to speak for "the majority of physicists" and at the same ask such basic questions.
Comment: 3. The Higgs idea is that in the QFT Lagrangian one may add Yukawa-type interactions with a scalar field. Under certain conditions these Yukawa terms can be recast as Dirac mass terms. The mere fact that term A in a key equation behaves the same as term B, is fairly common in theoretical physics. It does not automatically imply that "B is generated by A".
Comment: "Mass generation" refers to the appearance of mass terms through spontaneous symmetry breaking. This is caused by a non-zero vacuum expectation value of the Higgs field. But in the end it does not matter what you call it or how you view it, as long as you have understood the principle.
Answer: I'll only address your first question here.
To start off with a sidenote, I think the idea that mass is a fundamental property of a particle has been on shaky ground ever since Einstein showed the equivalence of mass and energy. I can hardly imagine it took very long for people to come to the conclusion that mass cannot be a fundamental property of particles. Today we know how this mass energy comes about: basically in a similar way to how an electric charge gains energy in an electric field. One difference being that we have no control over the BEH field, while we do have some over electromagnetic fields.
So the change that has come with the discovery of the BEH boson is that we've climbed down a branch in the Fundamentality Tree$^1$. It's like living in a universe where a fairly strong, constant electric field is ever-present and you know from experience that it is harder to move some particles in one direction than it is in another.$^2$ So you ascribe a fundamental property to all particles that might be something like a directional mass. However you have no idea why this property exists. And then you discover the ever-present electric field: you find out that your directional mass is simply the consequence of particles coupling to that field with some strength.
In this hypothetical universe, the BEH field might not be ever-present with a non-zero vacuum expectation value. Say it could, however, be straightforwardly induced in some way. The hypothetical observers in this hypothetical universe would then straightforwardly discover the BEH field coupling and the energy gain of particles associated with moving through it. They could immediately associate coupling strengths with particles.
In our universe, coupling to the electromagnetic field is much clearer and we can directly observe the coupling strengths of different particles. Contrary to the hypothetical universe from before, coupling to the BEH field is the less obvious one in ours. So now we are at the same height in the Fundamentality Tree for mass energy as we are for e.g. electromagnetic energy: the level of coupling constants. These are equally mysterious for the BEH field as they are for the EM field, in the sense that we don't know why they have the values that they do.

$^1$ I imagine the Fundamentality Tree looks a bit like this.
$^2$ This is a completely alien universe to us of course, as charged particles would be accelerated constantly but that is besides the point. Let's also leave out of consideration whether or not life could exist in this universe... And whether the universe itself could actually exist.
Answer: This isn't a complete answer to your question, just two comments on two specific points that came up that were too long for a comment:

WRT the Higgs having a spatially varying background because of inhomogeneities in the universe: It's important to keep in mind that the Higgs field is VERY MASSIVE when it has a nonzero VEV (as it does in the universe today). So even though, for instance, a planet could in principle create a spatially varying higgs field background [which you can compute classically to a good approximation], the range of the "Higgs force" is something like 10^{-17}m, so the background $H(r) \sim e^{-mr}/r$ is cutoff over a very short distance indeed leaving the Higgs field essentially constant.
WRT the vacuum energy of the Higgs: Indeed! The Higgs could in principle contribute to the vacuum energy and change the cosmological constant, this is one aspect of the cosmological constant problem! Indeed one of the original problems people like Anderson had with the Higgs mechanism was that it would give too large a classical contribution to the cosmological constant to be consistent with observations. Weinberg's perspective (in his classic paper on the cosmological constant problem) is that today we can think of the vacuum energy of the higgs field as being 0 (i.e.: $V(H)=0$ when $H=\langle H\rangle$, where $\langle H\rangle $ is the higgs vet today). This implies there was a larger cosmological constant in the past, when $H=0$! However, in the past there was also a higher energy density in matter and in radiation, and the contribution from these two pieces swamps the extra classical contribution to the cosmological constant from the Higgs field.


Is there a word for "to announce one's arrival"?

Question: Is there a word for announcing someone's arrival, kind of like a prelude for something or someone important?
Comment: Ironically, the best word, in general, *is* **announce**. Why do you think that a different word would be better?
Comment: Oh I was probably thinking of, how do i explain this...it's like when a king or any royalty arrives there's someone announcing his name and the kingdom he is from in a loud voice. It's the same for announcing arrived guests for a royal ball. So I thought there was a specific verb or noun for it or the person doing it
Comment: The person *doing* the announcing is the herald (which fits the answer below) or master of ceremonies.
Answer: What do you think of the verb to herald? It sounds like this one is exactly the word you're looking for. Here's how the Macmillan English Dictionary defines it:

(mainly literary) to announce something, or to be a sign that something is going to happen soon

Example:

The recent discovery of large deposits of gold is heralding a new era of prosperity in the region.
Comment: Thank you! This seems like the closest thing I was looking for
Answer: The thesaurus has:
Definition: declare arrival
Synonyms: predict, indicate, signal, harbinger, signify, forecast, herald, forebode, foretell, augur, portend, presage, foreshow, forerun
... All x of which have the problem that "i xed" or "i was xed" not neccessarily means " i announced my arrival" or "my arrival was announced" but can also be construed as "my existence was predicted".  So most can be used with arrival but none strongly imply arrival if the announced event is unspecified.
Answer: It's a little informal, but you can "verbify" the (normally, exclamatory) usage...

cooee - used to attract attention, especially at a distance. (oxforddictionaries.com)

...as in many of the written instances of things like...

As he approached, he cooeed loudly, but there was no response.

Apart from that, I do not believe there's a single-word (or simple "compound verb" based on self- prefix or reflexive oneself) English verb with the specific meaning draw attention to oneself, announce one's presence. But I'd be happy to be proved wrong!


Estimate on the interval of definition as parameter varies

Question: Given $\alpha\in\mathbb R$ can we give an estimate on the interval of definition of the solution of $$x'=x^2(\alpha+\sin(x)),\quad x(0)=1?$$
Answer: A straightforward but probably not optimal bound can be found as follows. Use $-1\leq\sin x\leq 1$ to get
$$ \alpha-1\leq \frac{d}{dt}\left(-x^{-1}\right)\leq \alpha+1.$$
Integrating over $[0,t]$, using the initial value and rearranging then gives
$$1-(\alpha+1)t\leq\frac{1}{x}\leq1-(\alpha-1)t.$$
How useful this is depends on the value of $\alpha$.
Comment: I'm afraid your calculations are not correct..
Comment: Thanks - I've corrected the calculation.
Answer: Since a closed form solution is not possible. You can use the Taylor series expansion $\sin(x(t)) =x(t)-O(x(t)^3)$. If you take $\sin(x(t)) \approx x(t) $, then you still can not get a nice closed form solution. In this case you can use the fact that $ \sin(x(0)) \approx x(0 ) = 1 $, since you are looking for a solution in the neighbourhood of zero. In this case you can solve the ODE by the method of separation of variables. Then you find the particular solution by exploiting the given initial condition. Finally, determine the domain where the solution $x(t)$ exists.
Answer: In order to get a global hold on the solutions of this equation one has to distinguish the seven cases
$$\alpha<-1,\quad \alpha=-1,\quad -1<\alpha<0,\quad \alpha=0,\quad 0<\alpha<1,\quad \alpha=1,\quad \alpha>1\ .$$
For each of these cases you have to draw a figure of the following kind: Draw a horizontal $t$-axis and a vertical $x$-axis. All solution curves will be graphs in this plane.  Then choose a "typical" $\alpha$ for the case at hand, e.g., $\alpha:=-{1\over2}$. Determine the zeros of the function
$$\phi(x):=x^2(\alpha+\sin x)\ .$$
When $\alpha=-{1\over2}$ these are the points $0$, ${\pi\over6}+2k\pi$ and ${5\pi\over6}+2k\pi$ $\,(k\in{\mathbb Z})$. For each of these values $x_\iota$ the constant function $x(t)\equiv x_\iota$ is a solution. Therefore draw a horizontal line at each of the levels $x_\iota$. No other solution can cross such a line. Between two successive $x_\iota$s the function $\phi$ does not change sign. It follows that between two successive horizontal lines we see congruent solution curves rising from $t=-\infty$ on the lower line to $t=\infty$ on the upper line, or vice versa, and having both lines as asymptotes.
Once one has understood this idea it becomes obvious that all solutions are defined on all of ${\mathbb R}$, as soon as there are an infinity of $x_\iota$s. This is the case iff $|\alpha|\leq 1$.
In the case $|\alpha|>1$ there is  only one zero of $\phi$, namely $x_0=0$. Here the solutions  only have a finite life-span (or pre-history, depending on the sign of $\alpha$), which in addition depends on the initial condition.


Site uses Javascript and I am having trouble accessing it using htmlagilitypack

Question: I am trying using a Windows Phone 8.0 Silverlight App to scrape data from PlayStation.
However, I believe the site uses Javascript and I am having trouble accessing it using htmlagilitypack.
My code so far is:
<code>protected async override void OnNavigatedTo(NavigationEventArgs e)
{
   base.OnNavigatedTo(e);
   string htmlPageLive = "";

   using (var client = new HttpClient())
   {
      htmlPageLive = await client.GetStringAsync("https://store.sonyentertainmentnetwork.com/#!/en-us/free-games/cid=STORE-MSF77008-PSPLUSFREEGAMES?smcid=pdc:us-en:ps-plus:sub-nav-new-arrivals");
   }

   HtmlDocument htmlDocumentLive = new HtmlDocument();
   htmlDocumentLive.LoadHtml(htmlPageLive);

   foreach (var div in htmlDocumentLive.DocumentNode.SelectNodes("//ul[@class= 'pane pane0']"))
   {
      PSPGames newGame = new PSPGames();
      newGame.Title = div.SelectSingleNode(".//h3[@class= 'cellTitle']").InnerText.Trim();
   }
   lstPSPGame.ItemsSource = PSPgame;
   customIndeterminateProgressBar.Visibility = Visibility.Collapsed;
}
</code>
However, the app is crashing on the 'foreach' line when it tries to look up the node 'pane pane0'.
Is it possible to scrape the data? If so, what would I need to do?
Thanks in advance.
Answer: It is not possible to scrape the data with HtmlAgilityPack since it is loaded asynchronously. What you get when querying the page is its skeleton.
What you could try is watch the network calls and see if a public webservice is called. Look out for json or xml data
Comment: Done that.  The calls made https://ajax.googleapis.com:443 and https://auth.api.sonyentertainmentnetwork.com:443
Comment: @kkerswell Did you find the data in a different call (I'm behind a proxy that won't let me check the page, I can't really go see what's behind these links)
Comment: Nothing that I can decipher no.
Comment: Have a look at this JSON data, this is what you need apparently, need to dig into it to get the games list: https://store.sonyentertainmentnetwork.com/chihiroview/viewfinder?https%3A%2F%2Fstore.sonyentertainmentnetwork.com%2Fstore%2Fapi%2Fchihiro%2F00_09_000%2Fcontainer%2FUS%2Fen%2F999%2FSTORE-MSF77008-PSPLUSFREEGAMES%3Fsize%3D30


Could a 2/3 majority vote be used as a consensus

Question: I understand that Bitcoin currently is using the chain with most proof-of-work as consensus. However could this method be improved, like only allow one block being generated at any given time, and each node verifies this block with its own past data. If there are more than 2/3 nodes prove the block to be valid then the block is added to the chain. If someone wants to create a fake block, then he must control at least 2/3 of the total nodes. What kind of attack is this consensus vulnerable to?
Comment: It's easy to make up rules, but much harder to precisely specify a protocol that securely enforces them.  For instance, what evidence could prove that 2/3 of nodes believe the block is valid?  What happens when an attacker spins up several million virtual machines, each running a node which claims their bogus block is valid?
Comment: @Yangrui, no, he couldn't.  That's the point of using proof-of-work.  It doesn't matter how many machines there are, it matters how powerful they are collectively.  VMs won't give you that power; the only way to obtain that level of power would be very, *very* expensive.  You'd have to purchase more computing power than the rest of the network combined.  Even if you had those resources, you'd have more to gain by playing by the rules than you would by attempting to break them.
Comment: Each node verifies the block with its own records. For the second attack, if an attacker can launch such large scale of an attack, couldn't he also out power the current Bitcoin network?
Answer: Your proposal is not sufficiently specified:

How is the authoring node selected?
How does a node prove his authority to author a block?
How do other nodes show support for the published block?
How can the support for a published block be verified by other nodes?

It is not clear how your proposal achieves consensus at all. Additionally, there doesn't seem to be a significant cost associated to vote on blocks, so the proposal is vulnerable to Sybil attacks.
Comment: Who decides which nodes are authorized?
Comment: Signing the header as approval means that not only does every node need to get every signature, but also every node must maintain a list of all other nodes and their public keys to gauge support. If anyone can start a node and start signing this will lead to disagreements in acceptance in a network where nodes drop in and out, as nodes will be calculating with different total signatories. Also when a third of the nodes is offline, no block can be validated... So, it's inefficient with bandwidth, will fork and is trivial to DOS. your proposal needs more work. ;)
Comment: @Yangrui, think about Nate's point.  If a node has to be authorized, then whoever is doing the authorizing controls the network.  You've just converted Bitcoin to being a centralized, permissioned system.  That sort of defeats the entire purpose.
Comment: I'm thinking that each node is equally authorized to vote right now. If a node approves a block, then it signs the block header with its private key so in turn other nodes can also verify who signed the block. If an attacker wants to attack the network, he must get the private keys of at least 2/3 of the total nodes first.
Comment: The nodes have equal voting power. So they need to vote . As long as a node does not commit fraud, it is allowed to vote.
Comment: @Murch good point. However, not all nodes need to be online. Yes the signature is verified against every node's public key, and all public keys need to be stored. However only online nodes are invited to vote at every round. The good point is that you can verify if the past blocks contain valid signatures only
Answer:
I understand that Bitcoin currently is using the chain with most
proof-of-work as consensus.
However could this method be improved,
like only allow one block being generated at any given time, and each
node verifies this block with its own past data.

No, it can't be improved in this way; not in Bitcoin's permissionless or decentralized threat model where any node can join and leave the Bitcoin network at any time. It would be worsened, actually.
To understand why your scheme doesn't work in the permissionless setting, you have to understand how sybil attacks [2] break it. It's very simple actually: an attacker can always win an election, if he can control a majority of fake voters. This is why your scheme won't work in Bitcoin's permissionless setting. In your scheme, the attacker can control a majority of fake voters by adding a bunch of nodes until he controls 2/3 of the nodes in the network. Then, he can dictate consensus.
In fact, Satoshi of course considered using a 2/3 majority vote (1 node = 1 vote) to secure Bitcoin, but soon realized sybil attacks would break any such consensus scheme because it is very cheap to create fake voters: just spawn fake nodes. The Bitcoin whitepaper clearly mentions this as well (see Section 4, pg. 3) [1].
It is crucial to understand that spawning nodes is as simple as generating key-pairs. In other words, a signature from a node is worthless in the permissionless setting. What does a signature really guarantee when any chump can spawn millions of nodes and provide millions of signatures?
Bitcoin prevents sybil attacks by making voting expensive. Again, since any chump can join the Bitcoin network and try to wreak havoc, Bitcoin essentially says "Have at it! But by the way, if you want to vote you'll have to compute a couple of trillion SHA256 hashes." Bitcoin still uses a majority vote to reach consensus but it counts votes not by number of nodes, but by number of CPUs. Why? Because chumps don't have a lot of CPUs. Thus, it'll be harder for them to take over the majority of voting power.
In Bitcoin, if I want to dictate consensus, I have to buy $160 million worth of ASIC miners (by some rough calculations) and then pay a huge electricity bill as well.
Now, you said that:

I understand that Bitcoin currently is using the chain with most proof-of-work as consensus.

...but it doesn't seem like you understand the reason why Bitcoin uses 1 CPU = 1 vote instead of using 1 node = 1 vote. Again, the answer is: to prevent sybil attacks.

If there are more
than 2/3 nodes prove the block to be valid then the block is added to
the chain. If someone wants to create a fake block, then he must
control at least 2/3 of the total nodes.
What kind of attack is this consensus vulnerable to?

Sybil attacks, as mentioned before.
Hope this helps answer your question.
PS: I'd like to point out that your system works fine in a permissioned setting where there's a fixed number of nodes or an admission control process which vets nodes before accepting them into the system. In this setting, sybil attacks are not a problem. However, keep in mind that this setting is the exact opposite of the Bitcoin setting. Bitcoin wants to stay decentralized/open/permissionless (and many other buzzwords Bitcoin fanatics like to use).
Comment: You're welcome! Your first solution doesn't work: By my calculations, an attacker can get 2/3 majority in around 4 rounds if he's the only one adding nodes (each round increases the number of nodes 1.333... times). Your second solution is Bitcoin's proof-of-work consensus. Not sure how voters could be awarded the same way. Recall that if it's 1 CPU = 1 vote, then if I have 2 CPUs, I will be awarded twice as much.
Comment: Thanks so much for your explaination. I've come up with two potential solutions to the imagined Sybil attack: 1) limit the number of new nodes being added at any round. Because attacker must outnumber existing nodes, the network can limit the new nodes not to exceed 1/3 of total nodes 2) add some proof-of-work mechanism to voting, but each voter are awarded the same way. I don't know which is better
Comment: Are there other proof-of-work methods rather than just calculating a hash for a trillion times?
Comment: Yes, there's a quite an amount of literature on that. If you'd like to learn more, it's probably best to ask a separate question on that topic.


If a wire is rated 10A, 120v AC. How many amps could I put through it of 13.8v DC?

Question: I am using a wire that is rated 10Amps at 120v ACwith a car headlight and a SLA battery.  About how many amps could this wire carry before getting warm or melting of DC current at 13.8volts?
Comment: You know the Amp capacity for the wire, but don't know the criteria for this "Ampacity" As I outlined there are many sources of criteria. Here is one for Solar Panels. http://www.altestore.com/howto/Solar-Electric-Power/Reference-Materials/Wire-and-Cable-Sizing-Calculator/a107/ If we assume you are using stranded extension wire and finding it warm with 10A, THat may match the NEMA rating for a 30'C rise in air of the conductor, not the insulator.
Answer: Unless you're working with RF (e.g. high-frequencies, > ~100 Khz), or really, really large wire (cross sections in inches), Amperes are Amperes are Amperes.
As such, a wire rated to handle 10 amps can handle 10 amps, independent of the voltage.
The voltage rating of wire generally relates to the breakdown voltage of the insulation. Basically, with wire rated to 120V, you can be confident that normal handling of the wire while it's energized with 120V will be safe.
If you were to put ~1000V on it, you might encounter issues with the insulation breaking down, and it could possibly shock or electrocute someone. However, this is a safety issue, and does not affect the wires ability to carry current.
Answer: The short answer is the same current rating is used for low voltage based on temperature rise. But if you can afford heavier cable for lower power loss, you gain with bettter %load regulation.
The Ampacity of wire is a function of temperature rise for sustained maximum current. This can vary depending if the wire is exposed to air, in a plenum or buried cable. AWG size varies depending on copper, Aluminum or Aluminum with a steel core for towers.
Power being transferred over high voltages and long distance, Utilities can waste 10% of the power to save on wire costs and allow a higher temperature rise such as 45'C rise or in some cases a 60'C rise.
In your case, I assume you selected 10A wire rated at 120Vac, which I believe is based on a 30'C temperature rise. The national electric code (NEC) specifies that the over current protection device not exceed 30A for 10 AGW wire, 20A for 12 AGW wire and 15A for 14 AWG wire.  You should know the length of wire to determine the desired % voltage drop and pick a number between 2~10%.  Car lights, I read are around 4% drop 1 way in wire.
Here is a chart for 2 wire 10% voltage loss - Wire Length vs Amperage @ 12Vdc.
Answer: The current carrying capacity of a wire is related to the size of the wire and not to the applied voltage. You can determine the size of your wire and then reference a standard wire table to get the maximum current carrying capacity for your wire. There are a variety of wire tables on the web and they are easy to find via Google search. Here is one that I have bookmarked in my browser.


Software to convert video to image sequence beside QT?

Question: I want to convert a bunch of videos to image sequence with user defined intervals, but I don't have an export to image sequence option on my QUicktime player.  Any suggestion?
Answer: I find it frustrating that questions like this exist on stack overflow, but do not show up on google -- oh well, long after my project had become old, I stumbled across this gem: http://www.squared5.com/svideo/mpeg-streamclip-mac.html
Works on Mac OSX Lion (and I assume it has compatibility with older versions of mac of course) -- I would get the beta version, it's more up to date and as of the writing of this answer, seems to be stable.
To export to image sequence (amongst other fun things such as zoom or rotating), go to: "File > Export to Other Formats...", then at the top there should be a format dropdown, one of the options being "Image Sequence"
When you click done, you are given the option to select a file name. Each of the image files will be that file name with a space and the sequence number appended (however you may disable the adding of a space in the export settings). The sequence numbers start at 1.
I realize this question is nine months old, but I am answering it more for prosperity -- hopefully people will be able to actually google for the answer to this question now, instead of aimlessly wandering the internet until they stumble upon a solution.
Up voted for good question with had to find answer :)
Other software that can do this:
Quick time 7 pro
kdenlive (extremely tedious format system, I suggest using ffprobe -show_streams to find out the avg_framerate (will be expressed as a fraction))
Answer: ffmpeg -i input.mkv -r 0.1 %06d.png saves a frame every 10 seconds. It always includes the first few frames for some reason.
mplayer -nosound -sstep 10 -vo png input.mkv doesn't always stop at the end of the video.
Answer: There are a few open source unix tools that can do what you want: https://superuser.com/questions/135117/how-to-convert-video-to-images
You might need to use Terminal though.


Smallworld: scoring points during decline of second race

Question: If I have a race in decline and choose to decline my current race, do I score both races or just the new race in decline? I am assuming that just the new race, since we (normally) cannot have two races in decline.
Answer: You are correct, when you choose to decline your current race, the previous markers of the previous race in decline are immediately removed and not scored (Unless of course the previous race in decline has the Spirit special power.)
See Entering in Decline on page 6 of the rulebook. Emphasis mine.

Each player can only have a single race In Decline on the map
  at any given time. If the player still has tokens from an earlier
  In Decline race left on the map, those are all immediately
  removed from the map and placed back in the storage tray,
  before flipping the new tokens into Decline.
The Race banner of the now vanished race is placed at the
  bottom of the stack of Race banners, or in the lowest empty
  slot in the banner column, if any. The same is also done when
  the last token of a race In Decline is wiped off the map as the
  result of their last Region being conquered.
The player can make no conquests during the turn his race
  goes into decline; his turn ends immediately after scoring! He
  gains 1 Victory coin for each Region his newly In Decline tokens
  occupy, but unless stated otherwise, he scores no Victory coins
  from his now In Decline Race banner power or discarded Special
  Power benefits.
Comment: "(Unless of course the previous race in decline has the Spirit special power.)"  Or if the current race, going into decline, has the Spirit special power.
Answer: This is an incorrect answer since the rule for Stout says you go In Decline "after scoring." This means you would score your previously In Decline race normally and then remove them from the board.
Comment: That's true for Stout races, but regular races go into decline before scoring.
Comment: Welcome to the site, and thanks for your input. On this site, each Answer should stand alone - if you want to mention this exception about Stout races, you should first give the answer for other races as well. If you just want to comment on another answer, after getting a little reputation you'll be able to leave comments like this one (which *don't* have to be stand-alone answers).
Comment: Also, if there are several answers, it can ambiguous what answer "this" refers to.


Is it possible to break the sound barrier in space with a really fast spacecraft

Question: I was doing some research online about slower-than-light interstellar spacecraft, and it got me thinking about a couple things. Although it may seem empty, the space between stars isn't a perfect vacuum. There's still dust, stellar wind, gas clouds, and many other particles floating around that make up the "interstellar medium". Although its effects are negligible for ordinary spacecraft, a ship traveling a good portion of the speed of light would start to feel "atmospheric" effects from all those particles running into it. So, is it possible to generate a supersonic shock wave if a ship travels fast enough?
Comment: _"Is it possible to break the sound barrier in space with a really fast spacecraft"_ you're deliberately trying to troll space-geeks right (with the questions title if not the meat of the following text)?
Comment: For reference : https://physics.stackexchange.com/questions/162184/what-is-the-speed-of-sound-in-space
Answer: There is no such thing in space
The speed of sound in an object generally goes up the denser the object is. For example, the speed of sound in air is 331 m/s; in water it is 1402 m/s; in granite it is 5950 m/s.
The method of propagation of the speed of sound in substances differs by their physical state; in space, the speed of sound would propagate as in a plasma. In outer space with few particles, a particle deflected by interaction with a spacecraft has a relatively low chance of hitting another particle.
The shockwave of breaking the sound barrier can be envisioned as a pressure  increase caused by particles stacking up against the moving object. But, in space, there simply aren't many other particles around. There is no pressure buildup, because there is plenty of space near a passing spaceship that a particle can relocate to without bumping into other particles.
So, nearly anything that is moving in space is already "breaking the sound barrier". Since we don't see the kind of supersonic shock waves you are expecting around satellites (or the moon), we won't see anything like that by going near to the speed of light.
Comment: Since as you mention, outer space is a plasma, there are actually many ways for shocks and waves to propagate without particle collisions. Basically, since all the particles are charged, a displacement of them creates an electric field that can propagate through the plasma under certain conditions. It'd still be hard for a spaceship to make substantial waves of this type though, since the wavelengths are extremely long.
Comment: Ok, but wouldn't a relativistic speed ship hit enough particles at once that it builds up pressure and drag at the front of the ship? Especially since the lorentz factor of the ship would cause space in front of it to compress as it gets closer to the speed of light.
Answer: You can have shock waves in the solar wind.
The solar wind is comprised of particles streaming away from the sun.  As in your OP, one could consider this as a medium similar to our atmosphere - although much less dense and moving much faster.  A fast moving thing plowing into this medium could generate the equivalent of a shock wave.
Focus: Solar Wind Shock Wave Gives Ions a Push

... These shock waves occur when a fast-moving pulse of solar wind
  particles plows into the rest of the slower-moving solar wind. Such a
  pulse can be created by a solar flare or other kind of solar eruption,
  for example. Particles in "fast" solar wind can travel up to two times
  faster than those in "slow" wind, which still zips along at speeds
  more than 1000 times faster than the speed of sound in air. The wave
  crest, where fast ions hit slower ones, is a compressed band of wind
  that has increased pressure, density, and temperature compared to the
  surrounding solar wind.

In the example, the fast thing generating the shock wave is faster solar wind, but it could be a ship - especially if it were a big ship or for some other reason had its zone of influence sweeping out a large swath of space and particles.  It is not a supersonic shockwave because sonic means sound.  But the analogous shock wave in the solar wind is similar to a shock wave produced in the atmosphere on earth.  If you wanted this sort of thing to happen in your story it would be totally plausible.
Comment: I am thinking this would be similar to the heliosphere/heliopause/terminal shock of our solar system. The heliosphere is so massive, traveling at a high speed in relation to the interstellar medium, it creates a sort of bow shock. not sure how powerful this is compared to a shock wave from breaking the sound barrier on earth
Comment: @Sonvar - what you describe is what I had read about before.  The linked article is a different aspect of the same (similar?) phenomenon as far as I can tell.


House rules to speed up Citadels play time?

Question: I enjoy Citadels, but find the game can often quite a long time. Since players must draft their role card in sequence, there ends up being a lot of down time while other players make their selections. The game is particularly prone to analysis-paralysis. Even limiting the game to a small number of players (4 or 5) and triggering the end game sooner (first player to build 7 buildings instead of 8), the game can still draw out. Any more ideas on how to improve the flow of this otherwise great game?
Answer: I played this game intensely a few years ago with 2 and 3 players (sometimes up to 4) and the analysy-paralysis problem disappeared after, say, 2-3 games with the same group.
I tried the same solution of lowering to 7 buildings (in fact, it is even suggested on the rulebook) and worked quite well for 2 players, never tried it with 3-4 players.
I personally think the hard time-limit is a too crude option. I'll try instead to insist on the players to 'think fast' in order to make a more agile game.
Notice that you can begin to think about which characters are the best for you on advance, while other players make their choose. And never forget that a little randomness on your decissions are desirable, as you'll be a perfect target for assassination and/or robbering the moment you become too predictable.
Answer: This is a crude instrument but you could try running a timer on decisions then deducting a player one gold OR their lowest value building if they exceed say, 2 minutes on a decision. I'll be honest and say I haven't tried this myself but my group tend to play quite fast.
Comment: Two minutes on a decision is *waaaaaay* too much!
Comment: I agree, and actually Joshuas answer contains the true reason for drag, typically I am always playing with one or two new players and so getting on their case too soon doesn't make it very fun for them.
Answer: Citadels is more likely to drag due to the experience level of players vs. number of players involved.
I too have had some lighting fast games with 2-4 players, but ultimately the speed of those games came down to myself and the other players being highly experienced with the game, knowing each role available, its power, and being able to make those choices (as well off call the roles as the King) in a short manner due to our experience.
The one time I played an 8 player game as well as my experience with 6-7 player games is that there will be 1-3 new/rusty players who do not remember the roles and are unable to make truly informed decisions and thus deliberate for awhile. They tend to forget which role they choose and do not immediately respond when their role is called out during play. Likewise if they happen to become king then they take a long time to call of the roles even with them in front of them.
The solution is simply to try to play more often and with experienced players, your time issue should self-correct over time. Additionally I've found that just about any competitive strategy game like this can drag if people tune out when its not their turn vs. paying attention and planning/thinking ahead as the turns progress.


Tools for managing Text Templates / Boilerplate Code or Snippets?

Question: I am looking for freely available tools to help manage text templates (e.g. for writing emails or other letters), boilerplate code and other snippets.
Preferably something open source or at least freeware.
Ideally, it would not be specific to managing source code, but would generally help manage all sorts of ASCII chunks (or maybe even RTF?).
Either something web based or cross-platform (Linux/Win32).
For example, I keep writing certain letters that would really only need to be slightly customized (e.g. change date, name, un/select certain phrases).
Any good pointers?
Thanks
Answer: --- code ---
For vim: SnipMate
For Emacs: yasnippets
--- non code ---
For general purpose snippets in windows: Texter