Is there a mathematical name given to the count of negative and positive numbers in a set

Question: If I have a set of numbers {-1, 2, 3, 4, -8, 2, 0, 44}
and I make the statement that there are:
2 negative numbers
5 positive numbers
and one signless number
Is there a mathematical concept used to name this count?
Thanks
Comment: In the special case that your numbers are the eigenvalues of a matrix describing a quadratic form, you can say that the form has _signature_ $(5, 1, 2)$. But in general I don't think so.
Comment: What Qiaochu called the "signature" would also be termed the *inertia* in some references.
Answer: I have no idea about the answer to your question, but I would like to make a general observation which is too long for a comment.
Mathematics thrives on brevity, accurate description and minimal sets of definitions. Its beauty is in the fact that with so little we can create so much, and prove further and further.
One can define pretty much anything, the question is why would you define something like that?
In most cases I have seen (and seeing now as I take my first dip into original research) definitions arise naturally from the work being done, or from some problem being dealt with.
For example, we see that if a function between two groups preserves the group's multiplication then it can be useful for us. We name it "homomorphism", further along the way we may see that it was more useful than we'd expect.
I can say that in set theory many times you find yourself baffled at notions of large cardinals, trying to understand why and how thought about them. These notions all came to be when someone was trying to prove something and needed "these sort of properties" - so he gave them a name. Sometimes you figure out that what you define is somewhat compatible to the things that were known before, and your definition represents a stronger, weaker or equivalent object.
In a way you found way to describe some idea, known or unknown. From time to time you actually come up with something new. These new ideas are hardly ever "out of the blue", as I said; they tend to be natural from some research.
Now you might find some idea useful when you solve a question, or two, or fifteen. However you need to consider what sort of problem this notion that you have defined helps you with, it might either help you define a problem or it could be a stepping stone in the solution. If it is indeed helpful, then it is useful.
There can be of course the need in shorter notation of something that you use a lot, but giving everything a short notation rises two problems:
The first is that not everyone will be familiar with your notations, and you would have to introduce and explain them often enough at the beginning - and so unless this notation is extremely useful it is likely that it will not catch on.
The second problem is that if you add more and more notations at a certain point it will overtake your work. It would be extremely hard to follow the work that you did, which is not a good thing usually.
To conclude, my point is that definitions and notations usually arise naturally when facing a problem we want to try to solve and/or define better; we may think that some mathematical object will help us in the solution and once this object becomes useful it tends to be named.
One last thing is that it is not customary to name things after yourself.
Answer: Cardinality is the term you are looking for, e.g. :
Cardinality of the subset of positive numbers for your set is 5,
Cardinality of the subset of negative numbers for your set is 2,
Cardinality of your set is 8
Cardinality of the subset of numbers=0 in your set is 1.


When should you use task-based navigation over topic-based navigation?

Question: What are the pros and cons of each?
Answer: Show controls which match users' goals:
Topic-based navigation is often well suited to situations where users want to find things out, eg. content sites.
Task-based interfaces tend to suit situations where users need to get things done, eg. applications.
Title buttons and links so that they fit with people's mental models of the goals they have in mind when they arrive at the site. You might find clues in the terms they use to express their goals.
Sometimes finding information is just part of a bigger task. Setting up a piece of hardware, for example might require a trip to the vendor's help system. In cases like this, you should still endeavour to determine users' goals, even though you might only consider yourself responsible for categorising content.
Answer: You should use tasks when the functionality is different but the topic the same.
You should use topics when the functionality is the same but topics are different.
Comment: Nice and concise. :)
Answer: You could also do both. What if you provided affordances to go in either direction.  Users would guess as to the "right way" to do it and always be right.
Comment: So you would use topics for features?
Answer: The CHI list has an interesting summary. Read more on the like to see the factors they mentioned.

In summary, there is no definitive
  answer to which is better: task-based
  navigation or topic-based navigation.
  Choosing the best approach depends on
  several factors...

Like what Glen said, you can do both. I prefer that, because you'll have the best of both worlds so why not? You'll just have to do the information architecture well to avoid clutter and bloat.
It's always fine to give away a lot of options as long as you can present them well and that your audience will appreciate them. If you have to stick to only one due to information architecture limitations or any other reason, research on what your market would prefer.
Answer: We use topic-based navigation in our UI and have observed that the user has problems because they want to do 'x', but some of our topics use language that doesn't convey any meaning to the user.
We could revise the topics, but we've found that addressing this by adding in task-based elements helps to guide the user and get them out of a 'so what do I do now' rut.
Really it boils down to the type of application you're working on. Task-based navigation would seem odd on a site like the BBC or Amazon.


Showing team members outlook calendar on a SharePoint calendar

Question: I was wondering if it is possible to show all the members of a team calendar on a SharePoint calendar? I know you have the calendar overlay option. I imagine when adding the calendar it would have to be approved by the user?
Answer: The Exchange calendars that are referenced are typically the shared public folder calendars which have a set address.  It looks like you can also reference the current user's calendar, but I've not seen an option to identify a team member's calendar.  It is also important to note that there is no approval process for a stated calendar, users would need to have access to view the entries.
Typically the way that I have handled a team calendar like this is to make the SharePoint Calendar support inbound email and have user's include that address when sending group meetings so that it can be displayed in the SharePoint as well as the local Outlook calendar.
Answer: If you are looking to see team member schedules on SharePoint 2010, you can use the Group Calendar feature.
http://office.microsoft.com/en-us/sharepoint-server-help/use-a-group-calendar-HA101810606.aspx
If you would like to add the actual appointments to a SharePoint calendar, this is not possible out of the box. We have been working on an Outlook add-in called ProperSync, which can connect an Outlook calendar to a SharePoint calendar. You can find more information at www.propersync.com.
*Disclaimer - I am part of the ProperSync team and hope this is a relevant and useful posting.


Too late to move a brew?

Question: I brewed an IPA yesterday. All went well and it is bubbling away today. However, my friend's brewing fridge/fermenting chamber just freed up and he suggested putting my brew in there. It would obviously be better to ferment it in the fridge with temp control etc. I'd have to drive it to his house (5 mins away). Is it too late to move it? Will that just oxidise the beer? Or is it early enough that I won't have to worry about that yet?
Answer: Go ahead and move it. You won't oxidize the beer - the headspace is already filled with co2, and the yeast will scavenge any oxygen that does make it into the beer.
Answer: 24 hours in, I don't think you have much to worry about. As mdma suggested, you still have active yeast that would gladly clean out any oxygen that finds its way into the beer.
That said, I would either move the fermenter very soon or not at all. The vast majority of your fermentation is going to happen in the first 2-3 days. That period of most active fermentation is when your beer is most sensitive to temperature. Once that very active fermentation has passed, it won't do much good to move the beer to your friend's temperature controlled fermentation chamber. The tail end of your fermentation just isn't going to have a sufficient flavor impact to make the move worthwhile.

Too late to move a brew?


Purchasing traffic effects on SEO

Question: I've recently found some websites which provide a specific number of visits by paying. I'm curious if this is a (very) bad practice for search engines (like Google).
Answer: It's not a bad practice, you can buy all the visitors you want. Most companies that offer these services will run a program connecting to your website through proxies increasing your unique visitor count. Though the visits will be less than a minute with 100% bounce rate.
It does nothing for your rankings and ruins your Analytics data. It's a waste of money and you are not having real people visit your website so expect no sales and no clicks on any ads.
Answer: Yes of course. This is a very bad practice nowadays. According to Google natural way of link building and organic traffic are the assets of modern SEO trend.
Answer: I have never seen any evidence that Google uses traffic to a website as a ranking signal.   There is certainly a bunch of speculation about it in this thread on WebmasterWorld.
If they did, they would have to very careful about it.  Google is the main traffic source for most websites.   Using website traffic as a signal would have to exclude traffic that Google itself sends, otherwise it would be a self-reinforcing feedback loop where Google sends more traffic and sees the website has more traffic, so it sends even more.
There is also the issue of where Google would get the data about which websites have traffic.  Google has several possible sources for this data:

Google Toolbar
Google Chrome Browser
Google Analytics
Google's malware blacklist
Google's DNS servers

However, they might be missing out on certain demographics such as Internet Explorer  users.
You could certainly make the case that Google should be ranking sites better because the are getting users.  Having users seems like it could be a sign of quality.  A couple years ago I remember reading about an online retailer with a huge ad budget that was trying to make the case that their large ad budget should be considered a sign of quality that Google considers in its rankings.

Purchasing traffic effects on SEO


Source ideas for monsters in a fantasy novel?

Question: Does anyone have any suggestions on where to go to get some ideas on different types of monsters that can be created for a fantasy novel? I'm not talking about different variations of zombies or vampires, but rather something more unique and original. I'd like to see some fresh ideas for mosters as antagonists.
Comment: The keyword to look up is "bestiary". A monster book / monster guide. Sometimes for a role-playing game, sometimes standalone.
Answer: Why just as antagonists? But well ...
One of the best monsters out there is a human being. A nice guy. No-one expects (i.e the reader) that he is a monster. A well known pattern with uncountable variations--use them.
Reading mythology of all kind (Greek, Northern, Indian) is a good source for monsters (Tolkien has proved that).
When your kid next time is afraid of that monster in the closet, don't tell him "No, there is none, I'll show you." Ask, what is so frightening. How does the monster look like?
Insects. Get a book, look them up. Magnified they are really terrifying.
Comment: I always thought the most terrifying monster was the one you see in yourself...
Comment: The most terrifying monster is the one you can't see and don't know where it is hiding.
Answer: Have a look around for the AD&D 2nd Ed. Monstrous Compendium (or whatever the current equivalent is under their new rules), which listed hundreds of possible monsters (I think there were several of these books). Easy enough to get ideas from these, or other RPG books.
For my own part, I tend to scour around for books on myths and legends from countries around the world, as they're a great source of inspiration when it comes to gods, spirits, demons, and monsters.
Alternatively, look at nature, and make up your own monsters based on the weird and crazy creatures that exist in real life. Believe me, there's enough of them!
Comment: +1 for using role-playing games' manuals. Quite a lot of fantasy writers openly use them.
Answer: You could borrow from deep sea creatures, there's some WEIRD critters in the deeps. Or look at tiny organisms and imagine them human-sized.  Or do something with weird plants.
Answer: Pay less attention to what the monsters look like, but rather what they do.
Is your monster simply a beast with fangs, muscles and acute hearing, or does it have special abilities? Are these abilities magical, or pseudo-scientific?
What is the monster's weakness? Like a good character, a good monster has weaknesses. Is it afraid of anything? Is there a specific way to kill it? Can it only attack someone who wields a weapon?
Consider making your monster represent something. Perhaps your monster can be the personification of fear, hate, hunger, sadness etc.
Answer: Look up "encyclopedia fairies" on Amazon and peruse some of the available books. Pick any being and start varying it. Cross a few. Add an unexpected characteristic. (Within reason. I think even Tolkien would be hard-pressed to pull off something like a half-vampire/half-weredragon who keeps kosher.)
Answer: I am not much experienced in writing but coming up with ideas for a creature is not a problem for me, so I will try to help [:
The first thing I think about is its function. For example, I had to create a creature that was linked to the hive mind and its duty was making food, or specifically farming. The farmer had following specifics: a plow on belly and two strong front legs so it could drag itself with ease. One leg in the back (three legs are exotic) for stabilizing. Its back was like a bowl where it could store harvest or take seeds from. Two small to medium sized hands for managing the harvest. One eye and no head as the hive mind controls it and it only needs to look forward.
So basically you think of what would be the reason for creatures existence, how it would survive, its function, and then think how evolution would handle it. You can take an existing (or non-existing) creature and then modify it to suite your needs. I also find useful crippling the creature in certain aspects, it makes them exotic, but don't overuse it.
You can also add to them random vulnerabilities that wouldn't get guessed so easily and can add to the mystery factor.
Hope I helped [:
Answer: I don't think it will be particularly helpful to you, but there is a book of imaginary beings that you might consult - read more here.
This book does not offer much details in its entries and list relatively low number of creatures - however, there are two characteristics that you might find interesting - it will give a really good overview of creatures that you can find in literature and, also, gives references and entry points that you can follow.
NOTE: If you want true originality then recipe is not possible, except very general ones such as: study the cultures (fictional, literally or national) whose legends you do not know.
Answer: I think fairy tales and folklore provide a huge resource for monsters. Around the world you can find an infinite amount of scary stories to crib from. You can take them and use them as they are, just bring them to the modern world, or you can re-vamp the to be a modern incarnation of the original.
One thing to bear in mind though is that no monster thinks it's a monster, they all think they are the hero of their own story and it's the erstwhile hero who is the bad guy. This is good advice iof you ever think of flipping the point of view of a story and telling it from the 'monsters' perspective.
Answer: RPG games are the great source of ideas for monsters, as good as spells. Some of them have quite a lot of magical creatures.
One of the games I've played have very many creatures with very strange names. This was Vallheru clone. In fact I've played in 2 Vallheru clones, Orodlin and Khazbanar, but both are based on the same source code available for free here: http://sourceforge.net/projects/vallheru/
I don't have the account there now, but there was a small description site for each of the monsters. All in Polish, but google translate would give you the idea what's going on. The names of the monsters can be found in SQL file in source code, here are some of them:

Orog
Lassaukaur
Dragon Beattle
Ekkimu
Alaghi
Kyton
Vintaru
Mymic
Mefith
Worg
Allip
Ettercap
Aranea
Girallon
Yuan-ti
Chuul
Lammasu
Beschalor
Couatl

Playing a lot of RPG games and noticing the ideas from them will also help you. Thanks to your question I've realized how much of this magic stuff I have forgotten.
Comment: I've found the list of monsters in published forms:
http://vallheru.net/wiki/doku.php?id=potworki


google chrome window resizes when click 12.04 kde

Question: All windows work fine but maximized G. Chrome window starts moving whenever I click under title bar without moving the cursor, but I don't want to move the windows, just to focus.
Under the title bar is next to the tabs, on the blue part.
This is annoying. It goes from maximized to moving windows function, with the cross instead of the pointer, only with single steady click. Using KDE 4.8.4, kubuntu 12.04.
Something like this http://code.google.com/p/chromium/issues/detail?id=37013.
How to solve this?
Answer: I experience the same issue with Firefox, pressing the Alt key resolves it, but it's still annoying as I don't know what causes the resize at the first place.
Answer: One workaroud is to use a chromiumtheme called "oxygenlike" and change som certain window rules specific to Chromium.
In that manner you avoid problems clicking inside the window right away, what happens if you don't use the standard KDE windowing.
The procedure is explained at: http://www.pclinuxos.com/forum/index.php?topic=78303.0
Even beter is to change the option in system settings, window behavoir, window behavior. Select the window actions tab. Whithin the "whitin inactive window" options choose for the left mouse button option "activate and bring to forground" option, but without "pass on click".
I use the dutch version of Kubuntu 10.04 LTS, so the menu/tab/button names can be slightly different in the english version than i translated it.
Comment: Welcome to AskUbuntu! While your link may in theory answer the question, you may want to add the details contained here, in case the link changes.


"Send by text/SMS" - is there a standard icon?

Question: "SMS" has proven to confuse some younger users in usertesting. The envelope icon is reserved for email. Is there an established or emerging standard that says "send this by text message"?
Answer: I think the use of a speech bubble is fairly common, however android seems to have stuck with an envelope (I'm an iOS man so forgive me if this is wrong)
A quick search shows mostly speech bubble related icons, some using text to further clarify.
Examples:

If I were designing from scratch I'd consider a speech bubble coming from a mobile phone screen - this shows it's 'chatting' (text message) and that it's something done via mobile.
Quick mockup of that:
Comment: Speech bubble seems standard for sms, and envelope for email. I can't find in android (froyo to ics) where they use an envelope, all I'm seeing is speech bubbles.
Answer: To distinguish a SMS message from an Email message iconographically I'd say you need to have that labelled in the icon.

The use of an envelope that is conventionally used on mobile devices, Android at least, groups both SMS's and Emails together, and would therefore not be a suitable choice.
Answer: There seems to be a trend with using some sort of speech bubble incorporated into it, looking at some of the SMS apps that are available on android we can clearly see:


Decent and affordable home monitoring setup

Question: Anyone have any good brands for some home monitoring speakers for a small budget? Looking at Bose, but otherwise, I'm for a blank?
Comment: Whats your budget?
Comment: Which Bose models were you looking at?
Answer: Check out KRK Rokits. Good bang for yer buck.

(source: krksys.com)
Answer: If Genelecs are in your price range you won't go far wrong at all.
Comment: Genelecs are definitely the way to go, if you can afford them.  They are incredibly reliable and accurate.
Answer: Adam A7, or the new A7X, if they are in your budget. Check the dynaudio BM 5A too, same budget. You really need to listen and try them. Maybe you can ask a reseller to listen to some material that you know, and compare the sound of different speakers.

(source: adam-audio.com)
Comment: I own a pair of these and I'm in love
Answer: Well, it depends what you mean by "small budget". I would go with a pair of small powered studio monitors, which would depend on the size of the area your are monitoring in (square footage, height, etc.)
Answer: Check out Blue Sky, Mackie, and Tannoy for relatively cheap, but decent setups. You do need to provide more info, like the size of your room...stereo or surround monitoring etc..
Answer: Hi!
Well...in my opinion you don't have to underestimate how much a good couple of monitors important is.
Budget is the first important thing: I wouldn't take KRK Rokits and Genelec. It would be better to find a couple of KRK V8. They are very good and they let you hear many things that other monitors use to hide. Genelec are very boomy and not accurate. They are very good for listening to music but not for work.
Adam too are very good, but for what they give are too expensive. On the other hand you could look for a couple of passive monitor, but it depends about your budget and if you have to move frequently. Yamaha NS-10 are a good standard but in my opinion are absolutely overestimated. If you look patiently on e-bay for a couple of B&W 805 Matrix I can assure you that it's the best choice that you can make. They are celestial.
What I must tell you is: buy used! Don't buy a new couple of monitor, beacuse you pay them too much and maybe in 6 months you decide to change them.
Furthermore it's very important WHERE are you going to put your monitors. Even if you buy a couple of Zingali and you put them in a bad (acoustically) place they will sound as a couple of Ipod's speakers.
Hope I've been usefull
PS This is only my opinion, about speakers everyone has his own liking. If you can go to a store and try them with your own hears trying to understand by your self.
Answer: I'm with KRK side
Answer: There are definitely trends in what monitors are being used across town (Los Angeles) and the industry these days, mostly what is popular during the time of purchase. For example, when I was an intern at Danetracks almost every editing suite was using the Mackie HR824; they are extremely reasonably priced and translate exceptionally well, both on large format stage situations and television. The new HR824mk2 are another story, as it is said that they do not sound as good as there predecessors and I doubt the decision to purchase Mackies would be the same if these were the speakers available back at the original point of sale.
I believe at one point M&K speakers were favored at Skywalker Sound, but as M&K is in a production slump because of legal issues at the moment, Dynaudio seems to be the choice now. (You can see what looks like BM6's with Ben Burtt in the special features section of Wall-E)
The Genelecs are amazing speaker for one reason alone: They are nearly perfectly flat in response. GENELECS HAVE TO BE TUNED. Almost every other speaker in the market has some sort of curve to it, either making the product sound amazing or lousy. Genelec are an amazing speaker but can be to punchy or harsh if they are not tuned for the specific room they are installed in. There is a good reason why so many studios use Genelec on their stages...
Where I am currently working we have a JBL 5672 5.1 system for mixing features, a 2.1 M&K for music, and a small set of cheapo Yamaha's for TV emulation. They all sound amazing.
The biggest point of advice I can give is this: Find out what your peers/co-workers/clients are using and emulate their setup. If I was working for Danetracks I would get a set of Mackies. For Skywalker I would purchase Dynaudios. If I was mixing strictly Television I would probably get a small pair of Genelec 8020's or 8030's. At home I have a Blue Sky 5.1 Media Desk system that I purchased used for $850. A great set of speakers for basic editing and basic panning. In my opinion you should refrain from Bose, not because it is a bad speaker, but because no one uses them for professional audio editing in our industry, that I know of or have seen so far.
Hope my rant was useful...
Nick
Answer: Monitors are very subjective and everyone will have their own opinion.  Your best bet is to figure out exactly what your budget is and what speakers are available in that range.  Look at sites like sweetwater.com or guitarcenter.com to see what is out there and get a good idea of price ranges.
Since you mention that you are looking for monitors on a "small budget" that leads me to believe that you basically just need something that will play back sound.  In most cases, you do get what you pay for, so budget as much as you can.  Otherwise, you will see yourself upgrading very soon.
I've owned 3 pairs of monitors in my career: Event 20/20's, because they were cheap and I needed something to get started. Then I upgraded to Mackie HR824's, because I became familiar/comfortable with them through many of the game studios I worked at.  After 7 years with the Mackies, I just upgraded to JBL 6328P's, and it is a totally different world.
Once you have narrowed down your budget, and have a few models picked out, you could ask for people's opinions on the specific models.  But, as a I said above, monitors are very subjective.
Answer: Three of the control rooms where I use to mix have installed Genelec 8050, 8020 and older 2029A. The last two ones are quite small so they may be cheap enough for a small budget. But I definitely wouldn´t recommend any of them. I wish I had Dynaudio BM6, but is not the case by now. One of this rooms have a pair of Yamaha NS10m so these are what I use when I mix there. I have a pair of Yamahas at home too.
If you don´t want to spend a lot of money  JBL Control 1 could work. They are passive although there is and active version. I´ve used the passive ones at postproduction a few times and I see them as a medium quality reference, a step under the Yamahas.
I´ve used small active Fostex 6301 but they are not detailed at mids so wouldn´t be a choice for me.
If you want to mix with quality reference for a small amount headphones could be a solution too. For the price of a pair of medium quality speakers you could get some good cans: Beyer DT880, Sennheiser HD25...
Answer: Adam's A7, Genelec's 80xx and Dynaudio's BM5A are discussed in this thread on GearSlutz: http://www.gearslutz.com/board/high-end/154894-adam-a7-vs-genelec-8030a.html. Even though this is the music production section it seems the A7 are more popular...
I'm looking for them at the moment, it could be my 600 euros frenzy of the year :)


Safely move Microsoft SDKs folder

Question: I have a folder on my hard drive, C:\Program Files\Microsoft SDKs, and I was wondering if it is safe to move it to an external drive.  Does Visual Studio or any other tool depend on this particular folder?
Answer: There are quite a number of entries in the registry (at least in my registry) that point to that location, so it seems something would work in a less than optimal fashion.  At a minimum, it would make the uninstaller a bit confused.  It is probably safe to simply rename the directory temporarily and try your builds to see if they still work.  Ultimately, though, it seems it would be cleanest to run the installation again to actually remove it and then install to a new location.
Answer: Yes. Most Unmanaged code in VSStudio refer to certain include files present in the include folder.
Also some exes in bin folder are also referred to (especially VS2008).
VS2005 refers to an internal Platform SDK location.
VS2008 refers to C:\Program Files\Microsoft SDKs\Windows\v6.0A
However most projects refer to this location via a macro. So if you can find a way to update the macro with the new location, then you should be fine.
Answer: Doing this may break some of your applications.  If you added a reference to a project by browsing to a DLL installed in this folder, that project will not compile after you move this folder.  If you haven't added any references in this manner, you might be OK.

Safely move Microsoft SDKs folder


Why the emphasis on Hebrew in Judaism?

Question: Why does Judaism have such an emphasis on Hebrew phrases in their religion and seems reluctant to translate them to English or another language?
Answer: Hebrew is the language of the Torah. The holy language. Translation inevitably creates a certain perspective on the text, as a Hebrew word can have multiple meanings or interpretations. A word for word translation would not make sense. The meaning often gets simplified, if not lost, in translation.
Answer: Hebrew is called "leshon hakodesh" ("the holy language"). The Rambam (Moreh Nevuchim 3:8) explains that the Hebrew language has no "bad words"; there are only euphemisms (to give one example, urine is called "the water of the legs"). Ramban (Shemos 30:13) writes that it is called holy because the Torah was written in that language, G-d is called by names in that language (vs. other languages — e.g. in English, "God" — in which the names don't have inherent holiness).
Answer: for the same reason tha Muslims chose to pray in Arabic. And the same reason that the Roman Church has preserved the Latin Liturgy.
Comment: And what reason is that?
Comment: how do you know the reasons are the same?

Why the emphasis on Hebrew in Judaism?


Are drop bars suitable for winter commuting?

Question: I've been told by somewhat knowledgable people that drop bars aren't suitable for winter cycling in snow and ice. Is there any validity to this? If so, why, and which style of handle bar would be preferable?
Comment: I've ridden drop bars a fair amount in the winter (never ridden with any other type of bar), though generally I stick to roads that are clear.  For me drop bars are a good thing in winter, since you have more hand positions and thus you can change frequently to prevent your hands from getting too cold.
Comment: What did they mean? Were they referring specifically to riding with your hands on dropped portions of the bars? Of did they mean that drop bars are unsuitable regardless of how you hold them?
Comment: I was told by a relatively experienced cyclist they they "don't recommend drop bars during the winter". I didn't have time to ask for clarification.
Comment: Follow up: I rode for many years through winter with drop bars quite comfortably, and never had a fall (at least, none that were caused by the wrong choice of handlebar).
Answer: Drop bars in of themselves are fine for winter riding. However, there are some peripheral issues involved. Your average flat bars will offer a bit more control in slippery conditions because flat bars are much, much wider than drop bars. A bike equipped with drop bars may not be the best bike for winter riding. But properly configured and sized drops can be excellent for winter riding.
Handlebar Width: Drop bars tend to be narrower than flat bars. You can mitigate this by getting wider drop bars; the ones meant for touring are great for winter riding.
Keep in mind that handlebar sizing isn't an exact science, but you generally want them to be as wide as your shoulders. A lot of road bikes won't have anything approaching this kind of width. (Also, there aren't that many wide, stocky roadies.)
Tires: Road bikes--which is where you usually see drop bars--often won't allow for the fitting of appropriate tires for riding on snow and ice. Not the fault of the drop bars!
Comment: I would think that a cyclocross or touring bike with knobby studded tires would be a good snow/ice choice.
Comment: I personally commute on the snow with drop bars.  My touring frame is wide enough to fit 700x38c snow tires with spikes and fenders. I also have wide drop bars (44 cm) and find there is lots of control.  That said, I agree a wider straight bar may give a bit better control in really extreme conditions. But snow riding ability really depends on your entire set up, not just one component.
Answer: I'll say it as bluntly as possible. The style of handlebars on a bicycle has absolutely no bearing on its suitability for winter conditions.
Comment: Yep. That sums it up nicely. Ride whatever you want, whenever you want. I freaking love riding my cross bike in conditions that cars wouldn't dare drive, and naturally it has drop bars.
Comment: But the width of handlebars has a large impact on how stable your bike is.
Comment: Define "stable". Wider bars give do you finer control over steering, but I haven't found that to be a limiting factor in a winter commute. Especially if you have proper tires for the commute conditions.
Comment: @sixtyfootersdude - It is also possible to get wider drop bars for more leverage.
Answer: Personal experience here, but I do not see any reason why drop handlebars wouldn't be suitable for winter riding. I have ridden extensively the past two winters with drop handlebars in ice and snow (Madison, WI). I personally find that in rougher and slippery conditions, I prefer riding with my hands in the drop position. It tends to give me better control while both giving me better access to the brakes and lowering my center of gravity a bit.
Despite snow and ice not traditionally considered commuting conditions, many choose to continue biking through the winter months. There are some good resources online with the best compilation I've seen being Chicago Bike Winter site..
One caveat I will make is that bikes that traditionally have drop handlebars aren't viewed as being optimal winter bikes due to typically having thinner road-style tires. Perhaps that is what the experienced cyclist was referring to.
Answer: Besides considering leverage as the only advantage of bicycling in icy and snowy temperatures, I would also consider the aspect of familiarity. My first few rides in icy/snowy conditions were quite nerve-wracking: constantly sliding right off the shoulder into the chocolate mousse or the ditch. I soon learned to avoid the treachery of the road shoulder and ride in the plowed area with the most asphalt exposed. One of the things that I felt good about was that I knew my bicycle well, and I wasn't making flustered or nervous mistakes with hand placement.
So, I would recommend focusing on keeping your hands and feet warm during the ride so that you are not impacting your ability to react or distracted by your extremeties. If it takes ziplock pogies and hand-warmers, or full-on BarMitts and Lake MXZs for your feet, being relaxed and perceptive to your conditions will make your ride safer than changing your ergonomics at the last minute.
And if you do ride in icy conditions and don't have studded tires, I would recommend those, too.
Answer: Seasoned winter cyclist here :-)
Drops and flats both work fine. One consideration with flats is that you are more upright, and so less vulnerable to the classic "front wheel suddenly sliding off to one side" in the ice/snow.


Which rights to photographs should I retain when writing a contract?

Question: The title says it all, but to clarify, assuming that the client does not have a specific contract that I must sigh or specific clauses that they want added, what rights to the photographs that I take should I retain for myself?
Answer: You should assert your copyright and all other rights (with the 'all rights reserved' clause), and explicitly grant the customer a licence to use the image for the purposes they need and no more, unless it's a royalty-free sale. If the image contains people or property you should check to see whether you need a signed release; if images of people are used for commercial/advertising purposes then without a release, the subject can reasonably demand a share of the profits from the use of the image.
Answer: Assuming the client has no specific clauses that they want added, then you should retain as many rights as legally possible, while still allowing the usage that you have specifically offered the client.


For how long can I stop doing cardio training before losing my endurance?

Question: I've heard that being ill for a few weeks or so is enough for your endurance to drop drastically. Is this really true?
Answer: Sadly I don't have access to the journal to verify, but Copacabana Runners is citing the journals Medicine and Science in Sports & Exercise and Sports Medicine, that reviewed over 60 detraining studies.
They found the following physiological effects after 2-4 weeks of detraining:

VO2 max:    down 4-10%
Blood volume:   down 5-10%
Heart rate: up 5-10%
Stroke volume:  down 6-12%
Flexibility:    Decreases
Lactate threshold:  Decreases
Muscle glycogen levels: down 20-30%
Aerobic enzyme activity:    Decreases
Running economy:    Unchanged

So basically your body gets hit across the board! Of course, your mileage may vary depending on your level of fitness (the more you have, the more you have to lose), the amount of inactivity you had (bed rest vs just no training) and most likely your age (the older you are, the harder it is to regain what is lost).
Answer: This really depends on your fitness level and of course the length of the break, but in general, yes, a few weeks of illness (anything over 7-10 days in my experience) will have your endurance drop. The more training you do, the steeper the drop will be, on the other hand you will also regain it more quickly. For the average fitness person (i.e. non (semi-)professional athlete) the drop shouldn't be too bad (but noticeable, nonetheless).
Having said this, if you are sick, you shouldn't train. Rather take the drop in endurance than risk a more severe issue.
Answer: Being ill for an extended (more than a 3-4 days) will always cause your endurance to drop. However, if you've reached a plateau in strength training due to excessive workouts, an extended rest will often cause a significant jump in performance, as you've built muscle that your internal organs could not previously support.


Where does the game-theoretic characterization of PH come from?

Question: I have read in a few places that $\mathbf{PH}$ can be interpreted in terms of the complexity of determining the winner in two-player games. I would like to know a) the original reference for this result and/or b) a concise explanation of it that requires little to no background in complexity theory (e.g., less than Goldreich's book).
Answer: The answer to part (a) of your question is this reference:

A. Meyer and L. Stockmeyer. The equivalence problem for regular expressions with squaring requires exponential space.  In Proceedings of the 13th IEEE Symposium on Switching and Automata Theory, pages 125-129, 1972. [pdf]

What an amazing paper this was!  Two later papers that discuss refinements of the result include these:

C. Wrathall. Complete sets and the polynomial-time hierarchy.  Theoretical Computer Science 3:23-33, 1977.
A. Chandra, D. Kozen, and L. Stockmeyer.  Alternation. Journal of the ACM 28(1):114-133, 1981.
Comment: That's great. I'd stumbled across the CKS paper but couldn't easily ID the antecedent papers.
Answer: Whenever you have quantifier alternation, you can think of it as a sort of game: one player picks what happens at each universal quantifier, and the other player picks the values at each existential quantifier. The existential player wins if the inner formula at the end is true, the universal player wins if it is false. The whole formula will be true exactly when the existential player has a winning strategy.
Different complexity classes correspond to different types of formulas. For example, any language in NP can be represented as the strings y so the $\exists x. \phi(x,y)$, where the length of $x$ is polynomial in the length of $y$ and $\phi$ can be computed in polynomial time. So NP corresponds to the games where the existential player can make a move that wins immediately. Working up the polynomial hierarchy, you get games (determined by the input) where the existential player always wins in 2 moves, 3 moves, etc., (where each move still has to be polynomial in size). And a language in the whole polynomial hierarchy is the collection of games where there is some fixed n, so that the game is always won by the existential player in n moves. In contrast, PSPACE is the games where the number of move can vary as long as it is polynomial in the length of y. (And the different formulas have to arise in some reasonably uniform way). This is how I usually understand why PH is contained in PSPACE, but then, I am a logician.
Answer: I'll take a shot at explaining this. The canonical problem in PH is a problem of this sort: $\exists x_1 \forall x_2 \ldots \exists x_k f(x_1,x_2,\ldots,x_k)$. (The last quantifier is exists or forall depending on whether k is odd or even. Let's take it to be exists for this example.)
The idea is to imagine two players, lets call them Eve (Player 1) and Adam (Player 2). (The names Eve and Adam were chosen so that Eve corresponds to the exists operator, and Adam corresponds to the forAll operator.)
Imagine that $x_1,x_3,\ldots$ describe Eve's moves in this two player game, and $x_2,x_4,\ldots$ describe Adam's moves. The function $f(x_1,x_2,\ldots,x_k)$ evaluates if these moves lead to a win for Eve ($f=1$) or a loss ($f=0$). There is no possibility of a draw.
Now the idea is simple. The value of the boolean expression $\exists x_1 \forall x_2 \ldots \exists x_k f(x_1,x_2,\ldots,x_k)$ exactly tells us if Eve has a winning strategy or not. In words, the boolean expression says this: "Is there a first move ($x_1$) that Eve can play so that no matter what Adam plays in his second move ($x_2$), there exists a move for Eve ($x_3$), so that no matter what Adam plays ........ there exists a $k^{th}$ move for Eve ($x_k$) so that she wins (i.e., $f(x_1,x_2,\ldots,x_k) = 1$)."
So the Boolean expression exactly expresses whether Eve has a winning strategy in this two player game.


How do I measure disk thrashing on linux?

Question: How do I accurately observe and measure the amount of virtual memory utilization and activity on Linux? I know there is vmstat, but how do I interpret the results? Or, what is better?
Answer: "vmstat" will tell you what you want to know. The "si" and "so" columns are showing you the amount of memory swapped in / out per interval. Both "vmstat" and "free" can show you the breakdown of memory usage. Rather than copy and paste the text, my answer here gives you some background into what those tools report.
Comment: perfect. I should have searched for vmstat. Thanks!
Answer: If the thrashing is caused by swapping then this line gives a good number:
vmstat 10 2 | tail -n1 | awk  '{print $7*$8}'

If the computer is swapping out, it may be OK. If the computer is swapping in, that may be OK, too. But if the computer is both swapping in and swapping out then it is bad.
Answer: Another useful tool is atop, which gives more detailed views of I/O than plain old top.
Answer: Have you gone thru the manpage?
man vmstat
If you need historical information, I use kSar. It has the additional useful ability that it can be run on a remote machine and gather information directly via ssh.
Answer: One of the great linux dilemmas is knowing which tool to use.  I guess that's one of the reasons I wrote collectl over 5 years ago.  It combines the best of most other tools to combine just about all other them into one.  In fact, it provides alternate formats of output so if you like vmstat output you just run "collectl --vmstat".  So why not just run vmstat?  Thats easy - collectl can also record data like sar but play it back to look like vmstat!  It will even play it back in a format which you can directly feed to gnuplot (see collectl-utils) or you can load it into exel or even RRD if you want to go that route.
-mark


Explaining what GIS is to 11 year old kid?

Question: Well, since it was one of the highest rated proposed questions, hasn't been asked yet, and I would love to know the answer, I thought I'd ask it.
How do I explain what GIS is for the 11 year old kid?
Comment: I tell you what you shouldn't do and that is show them the object model diagram for ArcObjects! You can watch the colour literally drain from their faces when you wave that at them :)
Answer:
This question has been converted to Community Wiki and wiki locked
  because it is an example of a question that seeks a list of answers
  and appears to be popular enough to protect it from closure.  It
  should be treated as a special case and should not be viewed as the
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Using Snow's Cholera map story. When John Snow mapped the Cholera outbreak in London, he noticed that most cholera cases appeared near certain water pumps. After these pumps were closed or cleared, the cholera outbreak stopped. This is how Mommy's/Daddy's work can help save the world!
In general, I always like to explain using images and vivid examples. A theoretical explanation is boring for an adult, not to mention a 11-years-old- child.
Answer: Kids often learn well through experiences, so I'd take them geocaching, and show them how the coordinates helped us find the cache. Afterward, I'd display the track in Google Earth or QGIS, and show them maps overlaid with our trail. Finally, we could calculate how high we climbed to reach the cache using a DEM, or display other data like rainfall to understand differences in plants growing along the hike.
Comment: +1 Excellent idea, if you have the time.
Comment: Yes, my 9 year old son, and 11 year old nephew both love geocaching, so when I try to talk about GIS, they just look at me like "Well duh."
Answer: Well I just talked about it with my 11-year old and he understood but was unimpressed.
Me:  "Imagine you have a map of our city and you want to colour it by income"
Him: "But isn't that money? How does that become colour"
Me:  "Perhaps I decide that high income is green and low income is red and incomes in between are colours in between green and red"
Him: "And you can use other colours if you want..."
Me:  "Exactly. The map has extra information attached that we don't see. I use that information to decide what colour to make things or how big to make them and much more.
Him: "Oh. Can I go back to my book now?"
Comment: The part of this answer that intrigues me the most is that he wanted to go back to a *book*
Answer: 11 years old might be a little young for Grand Theft Auto, but you could sit down with them, and show them this map, and explain > "I do this, but in the real world."
Answer: This kind of depends on how much time you have. I think one of the best ways to explain this to anyone is create some layers on overhead projector slides .. alternatively on powerpoint of similar electronic slides system.
The base slide could be square blocks on a grid/semi-grid. On top of this you can then place the 'road' layer. Next you could place the houses layer, trees layer, etc ..now you have a map of your neighborhood.
The next step is to place a square grid over the top of all these layers with numbers running up both sides. The numbers don't have to be real geographic coordinates.
Now you can begin to explain how GIS is a way of looking at information. We have all these sets of information that on their own don't really tell us much. That by knowing where to place the information on the 'grid' we are able to combine the information to give us the big picture(demonstrate how a layer which is not placed in the correct position breaks the picture).
So you are explaining that GIS is the way we get all these layers of information and combine them to reveal the big picture.
Answer: I find people learn best from examples they care about. So if he likes skateboarding, maybe explain how GIS could be used to determine the best place to open a skate park: near neighborhoods with lots of kids, but in an industrial area with large empty buildings for space.
Answer: I kind of assume here that you're talking to a group of children around the same age:
Explaining it to 15 and 16 year olds started with John Snow and Cholera (summary article on the Lancet) to keep them interested, before the standard "science of spatial relationships" bit. Couldn't tell you if that would work with 11 yr olds though...
Certainly Tobler's "Everything is related to everything else, but near things are more related than distant things" might help. You could do an exercise on what suburbs the kids live in - those closer to where you are are more likely to live in the same suburb, those from further away not so much.
Finally you could talk about scale of boundaries - country vs property say.
Answer: I use this explanation of GIS when I explain what I do to Adults as well as Children. I find it easier to explain using examples, but you often run the risk of getting oftrack and end up discussing the example itself, instead of the thing that you were illustrating, using the example as an metaphor.

Most of the Questions in life have some connection to Location. Questions like how do I get from this place to another? Or Who owns this land and just how much land do they own? Where else do they own this land? Till very recently, it was very difficult for computers to answer these questions, because firstly the information was not readily available, and when it was available, it was not present at one place. Even if it was present in the way we wanted, we often did not have fast enough computers which could answer solves these problems in a quick enough time span.
Let us come to an example. Suppose I want to build a mall in the city. I will first have to find out which land is available. If I find a suitable location, I might have to contact the people who own the area around that plot and inform them that construction activity will take place on this plot.
This kind of process is very easy for a person to imagine on a small scale, but gets very unmanageable on a large scale. GIS is a way at looking at these kinds of problems and solving them in the most efficient manner.
Answer: GIS (Geographic Information Systems) means maps on computers. Computerized maps are particularly useful because they can be searched and mashed up with other maps and data.
Comment: This is what I used to say when people asked me what I did for a living. But lately, I've been more explicit about the database component.
Answer: A few years ago my oldest son was in 1st grade and they were learning about maps one week. I printed out a few things I had done like a fire escape map, a map to get folks from the airport to our office, and a aerial shot of their school. They loved it all and totally got into it. The one they could relate to the most was the fire escape plan map, as their classroom door had one on it. I told them to always look on the back of hotel room doors for those maps as well. My point: Relate it back to maps, relationships between locations, and how what we "do" helps you solve problems and they get it.
Answer: With my kids, I tell them that it is about maps, places, and information about those places. My kids are under 6, so this works for the most part.
Probably getting really cool samples from http://flowingdata.com/2010/06/07/san-francisco-crime-mapped-as-elevation/ will really drive the point. Plus, since most of the examples are beautifully designed, so you will win more cool points from it.
This one is really cool:
http://flowingdata.com/2010/06/07/san-francisco-crime-mapped-as-elevation/
This is a more standard map, but with a powerful story in it:
http://flowingdata.com/2009/11/04/unemployment-2004-to-present-the-country-is-bleeding/
Answer: National Geographic have a good collection of learning tools that captives children and with interactive GIS games, this helps them understand geography and the environmental impacts humans have on our planet
http://test.mywonderfulworld.org/toolsforadventure/games/adventure.html
Explaining to a child:
GIS is maps(G-eo) and data/information (I-nfo) and computer (S-ystem) to bring them together and make sense of our world in a visual form.
Cartography..
Carto (to Draw)
Graphy (the Earth)
Answer: These videos might do the work, I wish my boss could check them out
http://www.youtube.com/watch?v=eAFG6aQTwPk old but still valid
Answer: Well, I would do it like this..
First comes the terms Geography and Information. Expected is that 11 years is enough to have a "basic" understanding of these terms.
Next simply show him a tourist map and point out how this map (a system) helps you glean information about the geography. How the museum is next to the park or how the super market can be reached using 1st street and also the 4th street.
You can also go on to pointing out how this park or museum resembles a square/polygon and roads are lines and how knowledge about the roads length can help estimate the travel time along it.
As an exercise you can encourage the child to sketch a map of the house or neighborhood and task him with accurate labeling etc.
Avishek
Answer: Perhaps a not for an 11-year-old, but I'm partial to the Geospatial Revolution videos, which I was originally introduced to by my geography instructor. Be advised that some contain mildly disturbing images of warfare; you may want to preview before showing them to young children, although they're no worse than what is common on the news.
Answer: Its very good question and one can explain with the example..So I have explained one of school going friend.
Its like the Burger or Veg Sand-which contains various layers and one can remove layer at any time..like finger-chip its similar the network..similar fashion I was able to explain point layer and polygon layer with the example then he told me that he understands the concept : )


Solving the system $\sum \sin = \sum \cos = 0$.

Question: Can we solve the system of equations:
$$\sin \alpha + \sin \beta + \sin \gamma = 0$$
$$\cos \alpha + \cos \beta + \cos \gamma = 0$$
?
(i.e. find the possible values of $\alpha, \beta, \gamma$)
Comment: Related : http://math.stackexchange.com/questions/1397066/clarification-regarding-a-question
Answer: Try something similar to what has been posted yet. Take one variable to the other side, then square and add the equations. What you get is $\alpha-\beta=120°$ and same for cyclic permutations (or negating all angles). The solutions is the three angles $\delta$, $\delta+120°$, $\delta-120°$ (arbitrary $\delta$) in any order.
EDIT: Or simply realize that the equations are equivalent to $\exp(i\alpha)+\exp(i\beta)+\exp(i\gamma)=0$ which make the answer immediately obvious.
Answer: Developing on Gerenuk's answer, you could consider the complex numbers
$$ z_1=\cos \alpha+i\sin \alpha,\ z_2=\cos \beta+i\sin\beta,\ z_3=\cos \gamma+i\sin \gamma$$
Then you know that $z_1,z_2,z_3$ are on the unit circle, and the centroid of the triangle formed by the points of afixes $z_i$ is of afix $\frac{z_1+z_2+z_3}{3}=0$. From classical geometry, we can see that if the centroid of a triangle is the same as the center of the circumscribed circle, then the triangle is equilateral. This proves that $\alpha,\beta,\gamma$ are of the form $\theta,\theta+\frac{2\pi}{3},\theta+\frac{4\pi}{3}$.
Answer: Try writing
$$
\sin^2(\alpha)=(\sin(\beta)+\sin(\gamma))^2=\sin^2(\beta)+\sin^2(\gamma)+2\sin(\beta)\sin(\gamma)\tag{1}
$$
and
$$
\cos^2(\alpha)=(\cos(\beta)+\cos(\gamma))^2=\cos^2(\beta)+\cos^2(\gamma)+2\cos(\beta)\cos(\gamma)\tag{2}
$$
then add $(1)$ and $(2)$ to get
$$
1=1+1+2\cos(\beta-\gamma)\tag{3}
$$
which means $\cos(\beta-\gamma)=-\frac12$. The same is true for the other pairs, so we get that each of $\alpha$, $\beta$, and $\gamma$ differ from each other by $\frac{2\pi}{3}$, which is the same answer that was achieved using complex means already.
Comment: Nice Answer without complex numbers.
Answer: Here's an algebraic proof : Write $z_k = e^{i \alpha_k}$. Then your equations are equivalent to $z_1 + z_2 + z_3 = 0$. Write $\theta = \frac{\alpha_1 + \alpha_2 + \alpha_3}{3}$ and $z = e^{i \theta}$
Expand the polynomial $P = (X-z_1)(X-z_2)(X-z_3)$. The $X^2$ term is $0$ by hypothetis, and the $X$ term can be written as $z_1 z_2 z_3 (z_1^* + z_2^* + z_3^*) = 0$. So $P = X^3 - z_1 z_2 z_3 = X^3 - z^3$. So the roots are $z . e^{2i k \pi /3}$.
Answer: More of a comment and less of an answer!

Well, your information seems to tell us that,
$$\cos(\alpha-\beta)+\cos(\beta-\gamma)+\cos(\alpha-\gamma)=-\dfrac{3}{2}$$
(To see this, square both equalities and add.)
I don't see any other obvious thing, you can do with these equations. If any thought plops up, I will type it in here.
Comment: Your relation should be with $\alpha-\beta,\beta-\gamma$ and $\gamma-\alpha$
Comment: @BeniBogosel I am sorry for having made that blunder. Thanks for the pointer. That the answer has posted, I'll flag it for the moderator to make it  CW.
Comment: Your result follows from my answer which shows that $$\cos(\alpha-\beta)=\cos(\beta-\gamma)=\cos(\gamma-\alpha)=-\frac12$$


Can two distinct spatially separated many-body systems in the ground state contain entangled particles?

Question: In particular, I am asking if two distinct many-body systems (e.g. system A and system B) separated at some arbitrary distance will necessarily be found to contain entangled particles (such that particle A1 is entangled with particle B1...etc) simply as a consequence of them both being forced into a ground state?  Specifically, can two experimenters go off to separate labs with no preparations made and then force their systems to the ground state and expect to later find through conventional testing of entanglement and sharing of statistical results that in fact they did share entangled particles?  Or will any entanglement only be coincidental?  The reason I ask is because I'm trying to find a way in which entanglement can be acheived by two separated labs remotely (without having to meet up..though classical comms would be allowed) since entangled states are so fragile. It is impractical, it seems, to meet up to prepare entanglement in one lab and then try to keep it from falling apart as you migrate to separate labs to take advantage of its utility or to test its sensitivity to distance (I'm assuming there is none, of course). Has this been achieved and if so, how is it achieved? Also, I have read a paper that documents that two distinct subsystems of a many-body system are entangled when the many-body system as a whole is in the ground state.  What I am asking here is that if that can be possible because the particles making up the many-body system do not have identity, why can't it be true of the particles comprising two separate many-body systems? Why are they not equally indistinguishable, if in fact they are not? Thanks
Answer: Yes in the sense that technically everything is entangled to everything else, if you were to consider a wavefunction representing the entire universe it would have some (probably small) level of entanglement of everything with everything else.  However for practical purposes the answer is no.
The bigger issue here is that the entanglement is with all the environment around each of the systems A and B (i.e. the labs, maybe a vacuum chamber?) is much stronger than the entanglement between A and B unless you do something clever in order to link the two together.
Being forced into the ground state means very little, it's just the ground state of the approximate Hamiltonian you consider each system to be influenced by, really it is connected to the other system (and the rest of the world) but by an amount that is usually made to be as small as possible.
Answer: The constraint you are describing defines a class of operations commonly used in quantum information theory called Local Operations Classical Communication, or LOCC. As you outlined, in LOCC you can only operate locally on each of your systems, and can only communicate classically between the two systems.
One of the main reasons this class of operations is interesting is precisely because it can not increase the entanglement between two systems. I've not been able to find a source with a good proof of this, but I think in your scenario it's relatively straightforward:
Consider your system $\rho$ which is a density operator in the space of operators on the joint hilbert space of the two systems.
$$\rho \in \mathbb{L}(\mathbb{H}_A \otimes \mathbb{H}_B)$$
You've stated that your systems start out non-entangled
$$\rho=\rho_A \otimes \rho_B $$
where $\rho_A \in \mathbb{L}(\mathbb{H}_A)$ and $\rho_B \in \mathbb{L}(\mathbb{H}_B)$
Now you only perform an operation $O$ which is local, but may be a function of a classical bit strings $S_A$, $S_B$ sent between parties:
$$O=O_A[S_B] \otimes O_B[S_A]$$
where $O_A[S_B] \in \mathbb{L}(\mathbb{H}_A)$ and $O_B[S_A] \in \mathbb{L}(\mathbb{H}_B)$
$$O \rho =(O_A[S_B]  \rho_A) \otimes (O_B[S_A]  \rho_B)=\gamma_A[S_B] \otimes \gamma_B[S_A] $$
where $\gamma_A[S_B] \in \mathbb{L}(\mathbb{H}_A)$ and $\gamma_B[S_A] \in \mathbb{L}(\mathbb{H}_B)$
this operation obviously produces a new density operator which is non-entangled, regardless of the bit strings sent, or the operations performed.
Answer: No.
Since you say that the two labs are at some arbitrary distance, this means there cannot be any interaction between them (since all known interactions in physics vanish at a long enough distance). This means the total Hamiltonian of the two systems is a sum of the Hamiltonians of each system:
$$ H = H_1 + H_2, $$
and as Hamiltonians of different systems, they commute: $[H_1,H_2]=0$.
Each Hamiltonian has its own ground state:
$$ H_1 |g_1\rangle = E_{g1} |g_1\rangle \\ H_2 |g_2\rangle = E_{g2} |g_2\rangle, $$
and then the ground state of the total Hamiltonian will just be the tensor product of the two states:
$$|g\rangle = |g_1\rangle \otimes |g_2\rangle.$$
This state obviously has no entanglement.
When you talk about two subsystems of the same system, that means you allow an interaction between the systems. This interaction will take the form of an interaction term in the total Hamiltonian:
$$ H = H_1 + H_2 + H_{int}, $$
And the interaction term needs not commute with either $H_1$ or $H_2$. In this case it is possible that the ground state will have entanglement between the two subsystems.


Why is latent heat required?

Question: Why is latent heat required for a system to change its state? (I.e. liquid water to ice) Why the "extra" energy?
Answer: The second part of the question is nicely answer by Martin. To the first part: latent heat is not always required. There are a number of examples, the paramagnetic to ferromagnetic phase transition is one of them that do not require or give off any latent heat.
A general sign for latent heat is if you have coexistence of two phases. Water and ice can coexist at 0 degrees Celsius and it takes energy to convert one into the other without any temperature change.
Answer: Forming bonds gives out energy, making bonds takes energy.
In a solid there are more (and stronger) bonds between molecules - so to melt a solid you have to put in energy to  break these bonds and allow the molecules to move freely. Similarly a liquid gives off energy when it 'freezes' as the bonds are formed

Why is latent heat required?


Would someone sustaining a spell effect negate their Stealth?

Question: Would someone sustaining a spell effect negate their Hidden status acquired by a successful Stealth roll?
I've checked the Essentials, and it mentions Keep Quiet under the requirements for Remaining Hidden on p.152/153
Answer: No
There is nothing inherent in the sustain rules that implies breaking the Keep Quiet requirement for remaining hidden.
In game, this implies to me that sustain is more concentration than it is chanting, stomping or otherwise taking un-stealthy actions.
Answer: Yes and No?
While I agree with Simon that there is nothing in the rules about it to dictate one way or the other, I think the GM needs to make a call on this as to how magic works in their particular world, and this needs to be spelled out EARLY on for the players.
If the GM dictates that spellcasting is something that requires constant chanting in order to sustain an effect, then I would expect that GM to rule that you could not gain Stealth because the character is making too much noise.
However, if the GM dictated that spellcasting did not require an oral component, but required only gestures, then it could be completely possible to sustain magic without making any noise.
Some GMs require neither vocal or oral components for spellcasting, which allows wizards and the like to keep casting even if they are silenced or bound in a game scenario.
I would say a chat with the GM about how magic casting works in their world is in order.  If they haven't specified any house rules on this, then the base rules themselves definitely aren't in your way.


the difference between diffuse texture and ambient occlusion texture

Question: is there any difference between diffuse texture which used in diffuse lighting and ambient occlusion map, or this is the same texture just different naming, because i see it mostly it looked the same?
Answer: Yes. A "diffuse texture" is generally just a flat, plain color map. It's one of the oldest kinds of texture map still in widespread use today. An ambient occlusion texture map takes into account local effects of light sources (and is usually just comprised of magnitudes, not actual colors).
The Wikipedia page on AO has an image that illustrates the difference visually.
Comment: +1 we have the same answer (you where 20 seconds faster though :) )
Answer: The diffuse texture is the colour of the object without light effects. The ambient occlusion texture is a map that shows the shadows on an object if it was evenly lid from all sides (basically it tells us how much a factor ambient light should be on each position). You can also do ambient occlusion real-time, but that's more expensive.
Sometimes the diffuse texture and ambient texture are combined in one texture.


How can I receive phone calls through Wi-Fi on an Android phone?

Question: How can I receive phone calls from a landlines/cellphone when I have Wi-Fi connectivity, but no cell phone service?
Answer: You could signup for Skype and get a Skype "Online Number" (this used to be called "Skype In") and then install the Skype app on your phone.
This would give you a real phone number that anyone could ring from a normal landline or mobile, that would ring through to Skype on your phone (or any other device) over your data connection.
Comment: I used Skype app to keep in touch with the UK while in India, it worked really well.
Answer: T-Mobile US has a Wi-Fi Calling app available, and other carriers might have done the same.  There might be charge for some of these services, but when I was on T-Mobile it was free.
Answer: Yes if you use a VoIP app and your cellphone service provider lets you divert your number on no connection - but remember that you will bear the cost for the diversion.
If you want to just have a wifi-based (VoIP) number that's separate from your cell number then any VoIP service provider will be able to do that - I have a test VoIP setup on my HTC Desire in the UK that lets anyone call my mobile on an 0845 number.
Answer: I you can get a free or paid SIP account and use something like SIPDroid.
Answer: I believe that Viber will do just that, if you're calling other people with Viber.
Answer: If your friends don't have viber you can use a MobileVoip
The list of voip provider supported is endless: http://www.mobilevoip.com/en/supported_brands


Is it a problem that my toilet flange is 3/8" below the surrounding tile?

Question: My tile setter had to elevate the tiles around the toilet hole in order to make up for some unevennesses.  As a result, the toilet flange is approx. 3/8" below the surrounding tile.  Can that be compensated for using extra wax ring or will it even be a problem at all?
Answer: A double wax ring will probably work but IMO the better option is a toilet flange extender.  It is just another flange ring that sits on top of the original flange to get it up to the correct height.  Then you install the wax ring and toilet as usual.
I don't have any experience with this particular kit but something like this Toilet Flange Extender Kit.
Answer: I have used the Set-Rite Toilet Flange Extender Kits for almost 5 years. They work great. Doubling up wax rings is okay if you want to make your waste line out of wax! These kits have a regular extender toilet flange which will bring your installation to the correct height n top of the finished floor.
Here is how your toilet flange is supposed to look and as you can see all you'll ever need is just one standard wax ring:

They have a couple of videos on YouTube that will help with your install and also have an email & phone support for the DIYer.
Good Luck, but you won't need it with these kits; it's an easy job.
Answer: I had a similar situation in my second bathroom, I just used two wax rings. No issues and it's going on about a year now. I've held off calking the toilet down to the tile just to make sure there weren't any "hidden" leaks, you may want to do the same at first just to verify that you have a good strong seal.
Comment: The standard trick to caulking toilets is to leave a gap at the back (facing the wall, where you can't see it anyway), so if there is ever a leak you can tell. You should never caulk all the way around.


Questions about using "to+ ing"

Question: I heard this sentence in a film:

We are one step closer to ending this.

I do not know why we have to use "ending" instead of "end".
Is "Step to" a phrasal verb?
Answer: Often, one finds oneself explaining that the word to preceding (often, but not necessarily, immediately) a verb form is not the preposition but the infinitive marker:
I want to go there.
Is it all right to eat in here?
Try to / and keep awake.
To see is to believe.
To err is human, to forgive, divine.
Their mission was to boldly go where no man had been before.
Notice that the verb form following the to is the base form; together with the infinitive marker, this constitutes the 'to-infinitive' form of the verb.
However, the to used here is the preposition (or arguably, particle - close to can often be replaced by near - and closer to by nearer - making close to a multi-word preposition):
We are closer to Denver than we were.
We are three miles closer to home.
We are one step closer to a lasting solution.
We are one step closer to ending this.
As Gulliver says, ending here is a word with both noun and verb properties, but the to is not the same word we use in I want to end this now.
Answer: Here, step means stage, and one step closer is a set phrase.
Here, the gerund ending is used, but you could also say the end of this. The -ing form is a bit like a noun.
Answer: In this case to is a preposition, not the first half of an infinitive.  We can say "We are one step closer to the end of this" with the same meaning.
Answer: Here, to is a preposition of the adjective closer, and after preposition usually gerund is used.

Questions about using "to+ ing"


"minimal" embedding of bipartite graphs on a sphere

Question: Here is an easy to pose problem I've encountered (but haven't been able to solve or disprove):
Let (V,E) be a bipartite graph with the following property –
the girth of the graph (i.e. the length of the shortest loop) is equal to the diameter of the graph times 2. i.e. if we denote the girth $2n$ then the diameter is $n$.
For such a graph and call an embedding of the graph into a sphere $S^m$ a function
$f:V\rightarrow S^m$
Such that there is a constant $k$ such that if $v_1$ and $v_2$ are connected by an edge then $d(f(v_1),f(v_2))=k$ when $d$ is the spherical distance (i.e. the length of the shortest geodetic segment on the sphere which connects $f(v_1)$ and $f(v_2)$).
Is the following claim true: does $k< \frac{ \pi}{n}$ implies that $f(V)$ is contained in a hemisphere?
Note that the settings are important - for any graph the answer is clearly no: take a triangle and embed it in the obvious way in a circle - so the diameter of the graph is 1 but the length of the arc between two vertices is $\frac{2 \pi}{3} < \frac{ \pi}{1}$ and the vertices are not contained in any half circle.
(One can say that I'm looking for a spherical Jung type theorem for bipartite graphs).
Comment: Are $n$ in $S^n$ and in the diameter the same?
Comment: No. thanks for the comment - I'll correct it in editing
Answer: Let $\Gamma$ be the metric space glued from segments of length $\pi/n$ along the rule described by your graph.
Note that $\Gamma$ is a 1-dimensional spherical building.
Therefore your question can be reformulated the following way:

Let $\Gamma$ be a 1-dimensional spherical building and $f\colon \Gamma\to\mathbb S^n$ is a contracting map. Then the image $f(\Gamma)$ lies in a half-sphere.


Hadlokos Neiros Shabbos and Yom Tov if one's parents are in a different time zone

Question: Does a child have to do their own Hadlokos Neiros (candle lighting) for Shabbos or Yom Tov if their mother is in a different time zone, or can the mother still light for the child?
Answer: You must do your own hadlakos neiros with a bracha if you are living next door.  Every house must have light and you make a bracha on the light.  The woman is charged with her own house for kabbalistic reasons (woman extinguished the light of the world- Adam...)  S.A. O.C. 263:2-3, 5-6
Comment: Source? please.
Comment: with Bracha without?
Comment: I edited to include source.
Comment: With bracha. this is not chanuka candles. the chiyuv is per house not per person.
Comment: @DoubleAA, what is your contrast to chanukah?  I didn't understand.
Answer: The semminary Rabbanim as a general rule in Eretz Yisrael forbid the girls from lighting their own neirot, claiming that their parents light for them(exception being Mayyanot and Lubavitcher Sem).  Claiming that a girl only lights when she is is married.
While I personally have never understood the exact logic behind their rulings considering Rabbanim like R' Eliyashiv and R' Shmuel Auerbach rule that way(according to the people who go to sems they oversee) I assume there is a valid halakhic reasoning behind it.
According to Sephardi halakha a woman lights for her own home and the woman of the house alone is permitted to say the beracha(The Hida Mihazik Berakha (O.H. 263:4) and Shoel V'Nishal (2, 58), Kitzur Shulkhan Arukh of HaRav Rafael Barukh Toledano (134:27), Sefer Ben Ish Hai(Year 2 Parashat Noah) Kaf HaHaim(OH 263:34), Ohr L'Tzion (Vol. 2, 18:3, there are others as well but that pretty much sums up most of the major ones).  They do permit a visitor to light in her own room with a berakha.
Rabbi Ovadia Yosef initially challenged this ruling(Yabia Omer 2 OH 16 and Yehaveh Da'at 2:33).  Essentially he ruled that since this was based on the Kabbalah of the Arizal and since Kabbalah is not ikar Hadin, that a girl should begin to light at the age of 3 with a berakha.  A view that was also later adopted by the late Lubavitcher Rebbe.
However, he faced such a firestorm from Rabbanim such as the Baba Sali(as well as some of the Gedolim listed above) that he finally withdrew his pasak.
All of that to say if there is a Ba'ala Bayit there an unmarried woman should not light on her own.
So it would seem that for the most part the answer to the overall question is no.
Comment: Which seminary Rabbanim?


What do I need to make a campaign?

Question: I am a sorta newbie DM (been playing for about 5 months) and I have a couple dungeons. So is that all I need to make a campaign? I have about 6-8 friends that I play with every week, but they are mostly newbies too. Any help?
Comment: Related: [I'm creating an original setting for D&D—where do I start?](http://rpg.stackexchange.com/q/1128/321)
Comment: Related: [What qualities are important when creating a fantasy RPG campaign?](http://rpg.stackexchange.com/questions/11/what-qualities-are-important-when-creating-a-fantasy-rpg-campaign)
Answer: If you're playing with a group of friends every week, in many respects you already have a campaign.
All you really need for a campaign, in my opinion, is continuity -- continuity of setting, characters, and history.
Now, if you want to create a campaign world, then you need some blank paper and imagination.  There are tons of websites out there that talk about creating a fun world.  One of the best to look at is the online archives of Ray Winninger's column Dungeoncraft, from Dragon magazine.
Comment: Actually, I suspect that the OP has been *playing* regularly, and has only been preparing to GM.
Comment: I agree - you have a campaign already.  Most other answers to this question would be ten pages long, you might want to pick more specific bits you want help with and ask those separately...
Answer: To make a campaign, you need only continuing characters.
To make a good campaign, you need additional continuity... of setting, of story.
Many campaigns use a map as the basis, putting various adventures' locations on the map. Most do well to have a mix of dungeon and non-dungeon adventures, as well. Further, travel to and from a dungeon can up the effective level of the dungeon by a level or two, by burning resources getting there, but the exact effects vary by game and edition...
If you prefer not to use a campaign map (and they aren't essential, but are useful), simply come up with ways to link the dungeons and explain why the PC's aren't threatened en route to/from the dungeons.
One of my favorite published campaigns has two adventures in one city - one in the city proper with mostly social encounters, and one dungeon crawl through the sewers. (It's for WFRP - The Enemy Within campaign.)
Another excellent one (AD&D's G1-G2-G3-D1-D2-D3-Q1 campaign) puts each module just a little bit further on - they flow together pretty well. So you might consider dungeons that lead through some barrier, leading to a new "base" - village or town - from which several more dungeons open up. One of which then leads on to yet another new base.
Likewise, a campaign map need not be graphical. It can be a "subway style" map, or even a text-only map like such:
<code>Dungeon_1        Dungeon_2 ----- City_of_Idriss
        \        /                /      \
        Village_of_Mookville ----/      Sewer_Dungeon
         /                  \         /
Dungeon_3                   Dungeon_5
     |                            |
Dungeon_4                        Village_of_Riverdown ---- Dungeon 6
</code>
Also, don't be afraid to reuse a dungeon, perhaps toned down following the last foray, perhaps entirely repopulated, or perhaps a duplicate. One campaign I ran used the same module (B2 Little Keep on the Borderlands) 4 times... as 4 different keeps of a standard pattern, with minor variations of inhabitants. (Pick equivalent monsters, and every time it says Ork, use Skeleton or kobold, for example.
The most important element to a good campaign is that it keep the players interested. My experience is that a sense of place is helpful, as are continuing story elements, and having a good time with each session and adventure.
Answer: While you're off to a good start, as a newbie DM, I would recommend that you work first on your skills as a DM.  Run a few modules as one offs.  Get practiced in how to tie chapters together into a coherent module first.  Once you get a feel for how to start tying elements of a story together, you'll have a much better basis on which to move on to a larger world.
From there you can move onward.  Take three or four of the modules you've run.  Come up with ways that those individual modules could be related to each other.  Think about the plots.  Is there a way that you can tie the plots together in a way that would support an overarching storyline?  Is there a common theme that you can derive from them.
Once you can start seeing ways of tying individual modules together into a coherent background story, you'll have a much better idea of how to create a world and an overarching story that will tie that world together.
I think the problem that a lot of DMs run into early on is in finding a way to tie together the various modules that a group will play into a single storyline.  Some groups are fine with that, just enjoying playing each module as it comes as a separate "world".  Other groups, like the one I participate in, have been playing in single world for about 15 years now.  And throughout that entire time we've run many modules all tied together into a single, overriding plotline.
So, in short, start small and work your way up.  When you reach the point of starting to create your world, begin with a plot.  What is the story that will tie your campaign together.  It doesn't have be big and detailed.  A short paragraph will do to start with.
Then begin with the beginning.  Flesh out the town where the campaign will start.  Start with a small village, one that's easy for you to map out and create a few major NPCs.  Nothing complex.
From there figure out what your initial campaign module will be.  What is the initial story that will tie your campaign together?  And how will your individual player's come together?   Let your players decide as much of their backgrounds as possible, but they'll all need a reason to be there.  While an individual game session or module is easy to say "You look trustworthy, come with us...", if you're going with a campaign, there is a much greater need for a story that ties them together somehow.  If you can get that, you will be well on your way to making your gaming sessions into a real campaign.
Comment: +1. Pre-made adventures are an excellent thing to lean on when learning, and to learn from.

What do I need to make a campaign?


What's different between gstreamer0.10-fluendo-mp3 and gstreamer0.10-fluendo-plugins-mp3-partner?

Question: I was installing some MP3 codecs when i noticed these two, why do we have two of these? what's different?
Answer: Raw package information:
Package: gstreamer0.10-fluendo-plugins-mp3-partner
Source: gstreamer0.10-fluendo-plugins-partner
Priority: extra
Section: sound
Installed-Size: 256
Maintainer: Brian Thomason
Architecture: i386
Version: 7.0.20100316-3
Replaces: gstreamer0.10-fluendo-mp3, gstreamer0.10-fluendo-plugins,
gstreamer0.10-fluendo-plugins-mp3, gstreamer0.10-fluendo-plugins-offline
Provides: gstreamer0.10-fluendo-mp3, gstreamer0.10-fluendo-plugins-mp3
Depends: libc6 (>= 2.4), libglib2.0-0 (>= 2.12.0), libgstreamer0.10-0 (>= 0.10.0),
libxml2 (>= 2.6.27), zlib1g (>= 1:1.1.4), debconf (>= 0.5) | debconf-2.0,
gstreamer0.10-plugins-base (>= 0.10.14)
Conflicts: gstreamer0.10-fluendo-mp3, gstreamer0.10-fluendo-plugins,
gstreamer0.10-fluendo-plugins-mp3, gstreamer0.10-fluendo-plugins-offline
Pre-Depends: debconf
Filename: pool/partner/g/gstreamer0.10-fluendo-plugins-partner/gstreamer0.10-
fluendo-plugins-mp3-partner_7.0.20100316-3_i386.deb
Size: 92048
MD5sum: 478ec57fd9233c5400a8c9784a27659d
SHA1: 2282a621166a18b1565c306c961a8ada2346ad99
Description: MP3 codec support for GStreamer

The GStreamer multimedia framework is being used in more and more systems,
ranging from server media processing systems, end-user desktops and various
embedded and mobile devices. The Fluendo Plugins are a set of plugins for
GStreamer which implement support for various media formats and hardware.
These plugins give you an opportunity to quickly and easily add proprietary
support to their GStreamer-based products.

This package contains an enhanced mp3 codec.

gstreamer0.10-fluendo-plugins-mp3-partner replaces gstreamer0.10-fluendo-mp3. Most likely the last one will someday disappear or be replaced by the 1st one.
gstreamer0.10-fluendo-plugins-mp3-partner contains an enhanced mp3 codec.
Answer: From what I could gather, the new -partner lib doesn't depend on liboil, which is GPL (or LGPL). The non suffixed lib does depend on that. Liboil is a library to handle optimizations (like using MMX, SSE or the like when it can).
Not depending on a (L)GPL library allows Fluendo to distribute their library more easily.
It is explained in better detail here: http://www.fluendo.com/shop/product/fluendo-mp3-decoder/
I quote:
"The fully licensed binary GStreamer plug-in
Fluendo has paid the license of Fraunhofer and Thomson to be able to distribute a binary MP3 decoder. This means that people who want MP3 support for the desktop music players can get a fully licensed plug-in directly from this site.
"
"Issues to be aware of
If you are living in a country where the MP3 patents don't apply, you are entitled to use the source code provided by Fluendo (or anyone else) to get legal MP3 support onto your Unix/GNU/Linux desktop.
In contrast, if you live in a country where patents do apply, or if you are a distribution maker working in countries where the patents apply, you need the licensed binary from Fluendo. If this is the case, please be aware that, even if our binary is made from MIT licensed source code, the resulting binary, combined with our license, is not free software, at least not GPL-compatible. This means that if you ship GStreamer with our binary MP3 plug-in, you need to be sure that you don't ship any GPL-licensed plug-ins that could end up being used together with the MP3 plug-in, as this would be a violation of the GPL. You also need to make sure you don't ship any GPL-licensed players which would use this plug-in.
"


Tips for adding more personality to characters?

Question: Often I read a new book only to find that the characters are flat, boring, and lacking in personality. Sometimes I even find that in my own characters, and when that happens I usually just remove it. Does anyone have suggestions on how you can keep this from happening with your own characters?
Comment: If your characters never surprise you, they will never surprise anyone else. Give them the freedom to be human, to act and speak of their own accord rather than rigidly adhere to the skeleton of a plot outline.
Answer: Characters tend to be boring if they're just normal, or mundane. To generalise, people want to read about characters that are slightly larger than life. I don't mean they should be eccentric, but they're that much more real, more determined, more passionate, cleverer, more diabolical, weaker, stronger than everyday people. They need to be dynamic characters, and by dynamic I mean they must not only suffer but be able to act in the face of their conflicts and dilemmas.
If you're using the words flat and boring, it invariably means that you have not created a well-rounded character that is full of the complex and often contradicting emotions, motives and desires that bring characters to life, characters that speak of an existence long before the story you are telling. The only way to achieve that is to answer all the possible questions you can think of asking about them, questions that cover three broad areas: the physiological (physical traits); the sociological (social class, education, childhood, friends, parents i.e. the events and history that shaped the development of the character); and the psychological (the result of the other two areas, things like phobias, weaknesses, guilt, emotions, intelligence and so on).
The best way to accomplish this is simply understanding people. Walk in their shoes. Why do they do or say the things they do? Ask questions of your friends, family, business acquaintances, even strangers. Why does the secretary at your work like sewing? What does she hope to be one day? Why did your friend not go to that particular party when the girl he liked would be there? Also, read newspapers, and delve into the people involve in the stories. Why did this woman steal people's identities? Why did that man kill his wife? Pay attention the mannerisms that people have, the little habits and things they do without even realising. Perhaps always playing with the hair, or flicking it back subconsciously out of the eyes. Or biting the lips.
Once you've created character sketches and done background research, the other factor to keep in mind is that you need to avoid clichés and stereotypes. The model who sees a fat girl in the mirror, and has an eating disorder. The crazy scientist. The happy, plump butcher with a red face. This doesn't mean you can't use these characters, but you need to play on these stereotypes and clichés so that you surprise your reader. The crazy scientist who isn't crazy, and merely cultivates this image because he feels he's a fraud, and uses it to hide his inadequacies, for example.
The best tip, really, is to just keep asking questions. Interview your character on a piece of paper. What would they say? What would you ask? What would the character's friends say if your were asking them about your character?
Keep in mind, too, that you should try focus on the characteristics that will have a bearing in relation to the story. This will bring out the best conflict for your characters, and help create obstacles. A basic example: a woman who is scared of dogs because of an attack in her childhood has a new neighbour that breeds pit-bulls, and she suspects he conducts illegal dog fights in an underground cellar. Or perhaps you make a male teacher so attractive that his classes are always filled with women, and no-one takes his ideas seriously. Choosing traits and characteristics with your story in mind is what will bring out the best (or worst) in your characters, and make them ooze personality.
Answer: The two main reasons for boring characters:

Missing eccentric behaviour
Missing conflicts

Eccentric behaviour:
The character is too good/too bad. He has never stolen something from a friend, never smoked, never drunk too much, never lied to his mother and caused much of trouble. Is he a decorated police officer and best father ever? Then he should have drown puppies when he was twelve.
The character has no quirks. Does he scratch his crotch in public? No? Why not? Does he have problems when encountering women? Encountering the world? Does he stand still for a minute with his mind wandering away? Does he get easily angry, shout at people, when someone mentions politics?
Characters need some imperfection to make them more like the reader. No-one is perfect. To identify with a character, he must be also imperfect.
Conflicts:
Maybe you have concentrated too much on the main conflict of the story. But the character needs to solve minor problems as well, like stress with the partner, or his kid has to repeat a school year. With these extra conflicts you get a more authentic character.
Also look at these related topics:
What does Character development actually mean?
Signs of Bad Character Development
Comment: *drowning puppies?!* You couldn't come up with a less sadistic character flaw, like stealing cigarettes and breaking car windows?
Comment: @Lauren: Why do you think it is called *conflict*? ;)
Answer: Everyone's mentioned the key points, but there's also a few exercises I like to use for digging deeper into those quirks and flaws of my characters.
One thing I use for exploring characters is to take them completely out of their element and see what happens from there. For example, take your medieval fantasy character and put them in the middle of a Black Friday sale. What happens next? How do they react? You'd be surprised what you discover about a character when they're placed in a totally different environment, and also, what happens will be completely character-driven instead of world or plot driven.
Going 'What if...' is also useful. What if they had a week off and all the money in the world? What if they had to choose between losing an arm or a leg? What if they knew the world was going to end tomorrow? What if they had to kill and skin a cute fluffy creature? What if the sports team they followed lost a key match? It can be as trite or as philosophical as you want (though I admit I enjoy the trite!).
My final (and somewhat random) suggestion is to think about their sense of humour. What makes them crack a smile? Laugh uproariously (do they even do that?)? Do they have a public and private sense of humour? Again, you'd be surprised what this can reveal about your character, and it tends to give them more dimension.
Answer: One thing that I do to help with character creation is to have a piece of paper with the character's name on, maybe even a picture (I'm not a fantastic artist so I usually skip this), then write down everything that you know about that character.
It's easier to categorize things (appearance, ideals, background etc.), and then pin it up on a wall. When you're writing a passage with that character in, keep looking back at it.
You need to think of the character as a real person. What would that real person do? Would their reactions to certain situations be realistic?
Then, as your character develops in your own mind and on the page, add to the character sheet. Your character will never stop developing and learning because humans never stop learning.
Your readers need to relate to your characters, and they will never do that if they do not learn from their mistakes.
And then, in order to to make an interesting character, make them a hypocrite. Not necessarily that they say one thing and do another, but establish that they are a particular way, and then have them surprise the readers by leading them into something that would generally be out of character.
It doesn't even have to be radical, it just needs to be human. Because humans aren't perfect.
Answer: Something that works for me is to consider their speech patterns. You don't want to get too extreme, but different people do express themselves in different ways, and you can use this to bring out their characters. The contrast between, say, a rather stuffy character and an outrageous one can be shown in this way. But again - the differences can be relatively slight and still be effective.
Answer: "Flat" characters are often stereotyped, cookie cutter characters that do everything that is expected of them. You want characters with contradictions, or at least with a ability to a surprise people.
A "dumb blonde" is a stereotype. A ditsy cheerleader is someone who makes most readers put the book down. A good looking blonde who has no interest in guys, aces calculus, and finally marries a top scientist is a much more interesting character. A nerdy, unpersonable "geek" is another boring character. A computer science major who is can hold his own socially (maybe is not top notch) will command more attention. A person from a rich family who is staunchly pro business isn't so interesting; a person from the same family who is a crusader for social justice is more eyecatching.


What is a durable, child-safe finish for a child's cot?

Question: I recently purchased a flat packed cot for my soon to arrive baby. The wood is plain without any paint or varnish. How best should I finish off the wood on the cot in a way that is both durable and safe for the baby?
Answer: Most modern enamels (aka "oil paints" or "alkyd paints") cure fully in 14 days, at least according to the product data sheet provided for the Sherwin Williams paint I just used for my friend's kitchen cabinets. Either way, an oil or water based enamel will provide a much more durable and resilient finish than a latex will.
I would suggest sanding the wood with 220 grit sandpaper, applying a high quality primer compatible with the final finish that you choose, and then a high quality water-based or oil-based enamel paint. I've really liked the results I've gotten with Sherwin Williams Interior Water-Based Alkyd and Benjamin Moore Advance Water-borne Enamel paints. They are true enamels, but clean up with water. Again, be sure to use a compatible primer. According to the attached technical data sheets, the waterborne alkyd paints take 30 days to reach their full hardness.
Answer: If the baby is arriving in more than a month, then pretty much any Latex paint should be ok.  Latex paint cures in 30 days or so.
If you're super concerned, you can find low VOC (volatile organic compound) paints online, although they're more expensive, and considering the number of kids that grow up in painted cribs w/o any harm, probably overkill.
I'd steer clear of oil based paints or polyurethane finishes unless you have a long enough time for the finish material to completely cure.