How does Digg calculate the hotness of a link?

Question: How does it decide to put something on the homepage? I know it's not only vote count, but what else is taken into account?
Answer: The exact process is unknown and has changed much over time. Votes from power users will generally have more weight then votes from non power users (At least it used to be this way) also collectively votes from common friends will have less weight. So 10 Votes from 10 people that are all friends will not have the same weight as 10 votes from 10 random people. Bury's will also hurt the chance of becoming popular. The system also looks at the voting history of users, even if they are not friends if multiple users have a history of voting for the same items it will also lesson the weight of their vote. It also seems that too many votes very quickly together after being posted will also affect it negatively. Comments left will aslo probably help.
Answer: It also takes into account the age of votes, and the frequency with which it gets them, so a post that gets 100 votes in an hour will rank higher than a post that gets 100 votes in 5 hours.
There are probably a lot of other factors that go into that aren't known, such as the rumor that users who have gotten to the front page before are favored and more likely to get there again, which could be why the top 100 users control 56% of the front page.


The merits and uses of Masking

Question: I was listening to my alarm this morning from a lofi telephone.  It's actually a step up from lo-fi so the sound quality is considerably improved, can't tell you the actual specs.  The alarm itself is this chill, padlike song for like 10 seconds and then it repeats, like any alarm clock.  So I was listening this morning and noticed that the piano part kind of blended in at certain parts with a pad in a very gentle way that made the piano's attack go away some and I was wondering if it was masking that I heard or just good mixing.
So it got me wondering how useful masking really is, rather than something to just be avoided.  Maybe I don't understand it well enough and maybe we can uncover some of the confusion and learn something new.
Comment: @chris, cool question!
Answer: Masking in a film mix is something to be aware of when preparing & layering sounds... I remember one case in particular where I just thought WTF?! It was in the film Black Sheep and this girl is being hassled by a 7 foot tall mutant sheep in the kitchen (!?) and to distract it her boyfriend grabs a haggis and throws it across the room, the thump of the haggis landing was what motivated the uber-sheep to stop attacking the girl & scurry across to sniff the haggis etc... I edited together a realistic 'haggis hits floor/wall' sound using 4 or 5 layers, put it up in the mix and it just didn't rate. Of course the score is playing the action/jeopardy loudly at this point, as are the uber-sheep vocals & the girl shrieking etc... So over the next half hour I kept adding layers until we had something that made the haggis landing rate in context. If you solo'd that haggis landing you would have heard a ridiculous over the top composite sound - a VERY hard hit combined with a subby short explosion etc etc.... But in context it just sounded quite normal, all due to masking!
Answer: Masking can be a useful tool, especially when it comes to dealing with noise issues in a given audio track (i.e. production audio). There's frequently noise components that you can't get rid of with noise reduction tools...well, maybe you can, but it usually hurts the rest of the audio in those extreme cases. If removal detrimentally affects the sound, attenuate the noise as best you can without adversely affecting what you need. After that it's time to look for your masking solution.
If you can incorporate it into your sound design (if it works aesthetically), a sound that has components that will mask the, now attenuated, offending element will finish what you started with the noise removal. You can do this with musical elements, sound effects or dialogue depending on the original sound.
A lot of people also forget that, in addition to frequency masking, there is also temporal masking. A hard transient sound can effectively mask a softer sound that occurs slightly before it. Yes, it will mask a sound that occurs BEFORE it. We're not talking about huge gaps here; more like on the order of 10s of milliseconds. It can, however, be just the thing you need to "hide" that element you can't get rid of.
Answer: Along the lines of something that Shaun has already mentioned -- something I learned quickly when first cutting (fast turn-around..) TV shows that have noisy exterior environments, is that nice tidy fade-ups on regions aren't always the best idea. If you don't have time to fill, or if the idea of adding more noise is just ridiculous, then cutting hard on the incoming dialogue can sometimes turn what would be a patchy edit in to a seamless one. I think it's a combination of not giving your ear any clues as to the change about to happen, and also that the incoming dialogue will mask the change in noise considerably, aided by the compressor tapping down the transients and lengthening the period that your ear has to get used to this new noise. It can make for a far more palatable edit.
It seems to me that the ear is far more accepting of an environment shift following dialogue than if it's preceded by it. To a degree of course..
And of course spending the time filling, expanding and/or noise reducing is better, but when the clock is ticking...
Comment: great point to mention. it's a psychoacoustic/short term memory thing. we lock onto the dialogue. depending on how long someone talks before we hear thr room tone, there's a good chance that it will keep most people distracted long enough to forget what the previous tone sounded like.
Answer: I work mostly in Games where no 2 playback systems are exactly alike.  My concern about masking is that it is very dependent on playback environment and equipment - very unpredictable.  Its a fine line(s) between masked, mushed, and overloaded.  Mixing is tricky at best in games, but where possible I err on the side of getting rid of freq range buildups and parts of sounds that are not relevant.

The merits and uses of Masking


Xorg ignoring wine application

Question: A wine application (Anarchy online, great game try it some time) is behaving very strangely.
While rendering correctly, Xorg isn't picking up on it's existence, and because of this the game only refreshes it's image when another application requests that portion of the screen to be updated.
For example, I will get maximum framerate if I move the window, or go into the compiz cube, while placing a terminal with top running in it behind the game will make that portion of the screen render at 3 fps (In the video I will link it's running top -d 1.0 hence the 1 fps) whereas a quickly updating window shows the game at a more reasonable framerate.
In the video I have uploaded you can see this strange behavior, as the output from the game and the top combine to basically split the game between fast fps and slow fps in real-time.
Video of Xorg/wine issue (AFAIK can only be opened in totem and VLC, recordmydesktop is bugged)
Wine bug report
Does anyone know how to fix this problem? Quick xorg config file? Recompile wine? I'll settle for a cheap trick (Other than putting a looping terminal behind the game every time, that really drains CPU)
Edit: Turned out it was a d3d bug, fixable by compiling 1.2.2 instead
Comment: you should post your edit as answer and accept it so this question doesn't look unsolved anymore
Answer: It was a d3d bug added in the partial fix to the 1.3.7 crashing in that same application, I compiled 1.2.2 and it now works.

Xorg ignoring wine application


Do thermostat-controlled, auto-adjust HVAC vents exist?

Question: The residential forced-air HVAC systems I have seen are controlled by a single thermostat in one room.  One has to manually adjust the vents in order to adjust the temperature in other rooms.  Is there such a think as thermostat-controlled, automatically-adjustable vents so that one can have multiple heating/cooling zones without having multiple furnaces and air-conditioners?
Comment: It's more than just the vent(s): To do this, you actually need a multi-zone HVAC controller (thermostat) - it has to be smart enough to know when to open a particular vent, and also to turn on the air handler whenever any vent is open. Ideally it's also going to optimize usage, eg, not turn off the air handler for one zone, then turn it on for another zone 30 seconds later.
Answer: There are various degrees of a "zoned" HVAC system.
A simple zoned system will include motorized dampers in the ducts to direct air where it is needed.  e.g. If one room is too cold, but the other ones are fine, the system will shut the dampers to the other rooms, and then fire up the heater so just the one room is heated.
More sophisticated zoning systems for larger house will include multiple heating/cooling units (e.g. one for the upstairs and one for the downstairs).
Zoned systems can also work on a schedule.  (e.g. keep the downstairs of your house comfortable during the day, but direct all of the airflow upstairs at night.)
As you can imagine, the control systems for such a unit get pretty complex.  Motorized dampers everywhere, control lines to all the dampers, thermostats in the various rooms.  It all adds up to a lot of money.  It is also a lot of stuff that can break.
Because of the complexity, most HVAC contractors will avoid doing a zoned system unless absolutely necessary.  It is usually easier to install a big air handler (enough CFM to cover the whole house), and then put a few manual dampers (1/10th the cost of motorized ones) and tweak them until they are right.
EDIT:  Another option to consider is a multi-split system.  Instead of having all your ducts connected back to one central air handler unit, each room/area has its own indoor unit, with its own fan and thermostat.  All of the indoor units have refrigerant lines that are connected to the outdoor condenser unit.  Each unit can heat/cool independently.  Some systems even allow simultaneous heating and cooling (good for server rooms in an office building).  Because they are ductless, they are a good fit for retrofitting a house with no ducts.  They do not make a lot of sense in an existing house that is already ducted, though.
Answer: Yes.
I was building a new home in Baytown Texas (completed in 2006) and searched far and wide for thermostat controlled dampers - was told by many HVAC companies that "they" remove them weekly - this isn't true.
I found one installer in Houston that would do the system the way I suggested - he listened and so did I.  We compromised on 2 units with 3 thermostats per unit.  After a bit of tweaking (adding sub dampers to rob air during critical times ie big party) this system performs well beyond expected and I would do it again.
I love the way my home heats and cools.  I can send A/C to the desired spaces and leave the others alone.  For example - wife is in kitchen in the morning working on breakfast - she gets extra cooling - as needed.  The office area - in summer, with 5 computers running, needs extra cooling due to the heat generated by the computers.  Night-turn on HVAC only in the sleeping areas - for best results, why would I cool the living room at 2 am when no one is in there?
My bill, for the size of the home is below average: my next door neighbor's home is 2k sq ft smaller and his bill is twice mine.  Also, there are 7 fridge/freezer/ice makers in this home, 2 A/C units and a hot tub.  Everything possible is natural gas-hot water, cooking, heat.
Thermostat controlled dampers was a home run and I am looking to install one in my mother's home.
Comment: I would love to hear more about the setup you went with and also would like info possibly on the company that helped you design this.
Answer: Speaking strictly from an performance perspective, it would be very difficult (neigh impossible) to set up a good variable air volume HVAC system if your furnace runs at a fixed speed.
As a hack - you could certainly set up a damper system with actuators controlling to a room temperature setpoint with no other changes to your HVAC configuration.  However, without the ability to vary the overall volume of air delivered, you will find situations where a single space hogs all the air available during a call for max heat or cool and the other spaces are starved for air.
It is pretty sad how inefficient and crude residential HVAC systems are compared to even a basic roof-top package air handling unit used at a strip mall or mini mart.
So to summarize - yes it can be done, but prohibitively expensive unless you are able to DIY a controller setup to monitor duct airflow(s), control a series of dampers and vary fan speed at the air handler itself.  That would require some sort of controller to handle I/O - you'll need a series of digital and analog inputs/outputs to make that work.  A proprietary controller for a dedicated HVAC application just for something simple like than can be several thousand dollars MSRP.  Based on my experience, the controls, configuration and commissioning can cost nearly as much as the physical equipment itself!
However, I would be very interested in a DIY setup like I described above!  Maybe something could be done w/ Arduino?
Comment: Caution: If the blower speed isn't adjusted along with vent dampers, closing vents can create undesirable pressure differences in ducts and living spaces because the same volume of air is being pushed through fewer openings.
Comment: @EvanJohnson undesirable in what way, exactly?  A remote-controllable, automated vent is exactly what I was thinking about for my home, because the inefficiency of a centralized forced-air system gives me such #sadface
Answer: One of my rental homes that was build about 3 years ago has a Honeywell thermostat system that zones. There is one air handler/AC/heater, a thermostat on the first floor, as thermostat on the second floor, electronic dampers in the duct work in the attic, and a controller in the mechanical room that connects to the thermostats, air handler, and dampers.
see this page from honeywell's website
Answer: If you're technically inclined, I saw one post hovering round the tubes about a guy that did some home automation - namely zoning, via 2 wire temperature sensors for the rooms, servo motors to control the registers, and a Linux box to rule them all.
Of course I can't find the link now that I look for it...
Comment: Here is the link: http://www.homeclimatecontrol.com/ Since your post, it acquired wireless sensors and actuators, and is on the way to getting rid of the Linux box now.
Comment: Thanks! I found some of these but I would like to retrofit my custom vents that came with the floor and none of these are really capable of that.
Answer: They're not controlled by the thermostat, but these vents are fairly cheap and can be set up to close/open on a schedule.
Comment: I don't think these [EcoNet Z-wave vents](http://www.smarthome.com/23324/EcoNet-EV100-6X12WH-Z-Wave-Controlled-Air-Vent-6-Inches-x-12-Inches-White/p.aspx) are the exact same ones (it's been a while since my original post), but they have the same capability plus smartphone connectivity. They're quite a bit more expensive though.
Comment: Do you perhaps have a link to the actual product you were linking to? The link is broken.
Answer: I've never seem them in action before, but apparently people do make them.
Every time I've seen multi-zone heating in a house, it's always been boiler based.
Answer: Another supplier (I have no connection to them beyond them being based in my home state, which is how I know about them): Home Comfort Zones
Answer: Try this website:  http://www.theactivent.com/
The wireless controlled vent cover costs $35 (may need multiple per room), the wireless temperature sensor (one per room) $30, both together cost $50.
Comment: Please declare any affiliation that you have with this website.  See the [faq#promotion] for the rules for self-promotion on this site.
Answer: There is a new player in this industry, but they're running about $100 per device with Nest integration: https://www.ecoventsystems.com/your-system/


Remotely fingerprint AV software on LAN machines?

Question: Does anyone know of a method to fingerprint machines in the LAN and find out what kind of AV software is installed?
Comment: I'm sure something could be gleaned from the signature update transactions, if you're willing to wait for them.
Comment: True! Thats a very good idea.
Answer: There are two ways to detect this, Passive or Active.
Passive
This is what Iszi was referring to. If you can get yourself in the data stream you can glean lots of information. Using flow analysis you can watch for machines making connections to known update servers. So look around at some AV products, get a list of IP addresses from which they serve their updates, and then filter on some of the common data transfer ports. For AV this tends to be either HTTP, both 80 or 443 or FTP.
If you have access to the data stream directly, whether through a tap or span port, you can do some deeper analysis. Here, you can actually troll through the communications channel to look for signature bundle downloads. Depending on the vendor you may even be able to get exact product and/or version numbers from the UserAgent or filename of the signature bundles.
Additionally, if you have an IDS/IDP in place, you could likely construct your own signatures to look for this kind of behavior. Or, better yet, your vendor may even provide some. For example, Sourcefire ships a very large contingent of "Policy" signatures that allow you to look for corporate policy violations such as browsing job search websites, performing Google Images searches with SafeSearch disabled, or using Skype. You may be able to find application signatures for AV in a package like this.
Active
This is what you really want, to log into the systems themselves and check the software inventory. Being able to do this is highly dependent on your organization and how how much control you have over the client machines. If you have administrative access to the systems, you can remotely log in and pull whatever information you want. Nessus, for example, given Administrator privileges will perform a full software inventory. Or, the same information can be gathered through SCCM. You can always resort to writing a WMI a script to remotely poll, but there are so many better tools out there now, that you shouldn't have to.
If you're lucky enough to have a NAC system in place, you could also perform this polling as part of your pre-authentication posture assessment. Of course, if you're lucky enough to have a fully functional NAC in place, then you're probably lucky enough to have some of the other methods available as well.
Answer: Do you have access to these machines from an admin standpoint, it might be difficult to tell AV software based only on a vulnerability scan.
If you have admin access on these machines, you might be able to pull WMI or some other service. Using something like a credentialed scan with Nessus will often tell you what AV is installed or can be used to get a list of all programs installed and running services.
Without access from just the network level, you would need to passively capture traffic looking for signatures back to a local update server or to IP addresses of known remote AV server.


How to pass the UI control values as the parameters to the Controller in Rails?

Question: I met a problem of parameter passing in Rails.
I have an object named 'account' and another object named 'locale'. There is a one-to-many relationship between them. One locale can be mapped with multiple accounts.
On accounts/index.html.erb, I have a dropdown which will list all the available locales.
And I have a link below.
In expectation, when I clicks this link, the index method of account controller will be called and the value of selected locale id will be passed. And the index method will retrieve all the accounts belonging to that locale.
What blocks me is I have no idea how to pass that selected value of dropdown to the controller.
I only know the basic way of passing a parameter is:
<%= link_to 'Refresh', {:action => 'index', :fromvar => 'refresh', :selected_locale_id => '1'}.

And from controller, we can get it by:
params[:selected_locale_id]

But it is the case of a fixed value. How to deal with a dynamic UI control value as my case?
Does link_to support some javascript to be embedded?
My rails version is 3.2.13.
Any one has idea on this?
Answer: You can either do this as a form, or as javascript in the onclick event of the link. I would recommend a form.
The following should get you started:
<%= form_for :index do |form| %>
  <%= form.select :locale_id, Locale.all %>
  <%= form.submit %>
<% end %>

Be sure to add a post route to the index action to allow the form to submit.
Comment: Thanks for the reply. But I do not quite understand how to add a post route to the index action to allow the form to submit. I only have "resources :locales" and "resources :accounts" in routes.rb. Any change shall I apply in this file?


How do I download all my blogger posts?

Question: Is there any way I can download all my posts from blogger?
Answer: You can use this tool called Blogger Backup. Its free and open-source.
Answer: How to save entire blog as PDF
If you want to save your entire blog as an awesome PDF file which people can read and enjoy instead of having a dull .xml file, use Blogbooker or follow these steps:
Step 1: Blogger dashbord>Settings>Posts and comments>Posts> Show at most
Put show at most 999999 posts on the main page. (Any large number)
Step 2: View your blog website. Print it (Ctrl+P) and choose the destination as "Save as PDF". Click on 'Older posts' and repeat. (If you have a lot of posts you'd have multiple pages so you'd have to click older posts) You should have multiple PDF files.
Step 3: Go to PDF combine and combine your PDF files.
Answer: If what you're looking for is to take your blog with you, exporting it is the option; unless what you're looking for is to export only your posts.
To export your entire blog:
Exporting > From your blogger dashboard > Settings > Under BASIC Tab > The first block is Blog Tools > Export.
Save the file and then upload it where you need to.
Comment: The export option is no longer available.

How do I download all my blogger posts?


Improvement patents, building your technology on top of already existing technology

Question: My question is regarding improvement patents. I have read some literature online, but it's all still pretty convoluted regarding this issue of improvement patents. My question is how does building your technology on top of already existing (and most likely patented) technology work. For example: computer mouses at one time all used wires to attach to the computers and send signals back to the computer and one day I came along and decided that I was going to remove the wire and instead use wireless tech. (Bluetooth, WIFI, w/e the details are irrelevant). How do I determine whether my new technology is patentable and does not infringe on the existing technology that is probably patented itself?
Comment: Welcome to Ask Patents! Like all SE sites Ask Patents wants questions that are actually worded as question, particularly the title. Also your posts will be much better received if they use standard capitalization.
Answer: There are two separate issues here that are very frequently conflated. Your ability to get a patent has nothing to do with what others have or have not patented per se. It has to do with what others have done and allowed public access to. Your invention will be looked at in comparison with previous publications to judge the novelty and non-obviousness of your idea. The previous publications can be patents, expired patents, patent applications that were totally rejected, magazine articles, etc.  A large % of issued patents would be considered improvement patents. If you search for issued patents on manual tooth brushes you will find a vast array of attempts to improve on the basic tooth brush.
The first wireless mouse may have been non-obvious altogether or maybe the inventor had to create a special protocol or other technology for the mouse to be low power enough or maybe some inventing needed to be done to bring the cost down to the point it was practical to put wireless in a low cost device.
The second issue is  - if you made your invention would it infringe on an existing patent for the underlying base technology? If someone had a patent on the optical mouse, your wireless optical mouse might very well infringe. That doesn't mean you can't get a patent, it means you can't make it or sell it.


When do you use Doran's Blades in top lane on a Bruiser?

Question: I like top lane. I watch streams to help learn and I sometimes see the same person building dorans on say... Olaf instead of a phage or warmogs. When do you go for dorans over bigger items?
Answer: This strongly depends on the match-up and how well you're doing. If you're against someone who you can trade against easily and always come out on top in said trades getting a Dorans will generally be a better idea because it'll improve your damage more than low level alternatives. This is generally true if you're playing a champion that hits harder versus a more tanky champion that doesn't deal as much damage. Say Riven versus Cho'gath for an example, Riven would probably want to grab x2 Dorans before going into her build to give her more damage potential on Cho'gath since she normally comes out on the good side of trades.
Alternatively, if you're getting bullied pretty badly you can always go for Dorans items (they're fairly gold efficient), though I'd probably recommend getting a Wriggles because of higher sustain and the damage reduction. A lot of top lane is knowing your preferred champion's match-ups and how well he/she trades against their enemy in lane.
For a little bit a math on Dorans Vs Wriggles I'm gonna add a link to another answer on here. Just for Context: The question is about Dorans Vs Wriggles on an AD carry, but the math still applies universally. https://gaming.stackexchange.com/a/59537/7494
Additionally, if you get fed early and can afford beefier items you should almost always go for those, but getting Tier 2 Boots, x2 Dorans, and a cheap defense item at low levels will almost always be better than trying to save for a 1.5k+ gold item early.
Hope this helps :)
Answer: Simply put, Doran's items give the most bang for their buck. Their biggest disadvantage is that they cannot be built into better items and thus tie up an item slot, but that only becomes a problem 25 or more minutes into the game. All Doran's items are focused on sustain (lifesteal and regen), and getting early sustain is very important for getting gold and xp.
However, watching high level games can be misleading. High level players are very skilled at avoiding damage and getting their farm and xp, and they don't make a lot of mistakes. Also, they usually play draft pick games (Normal or Ranked) so they know who they are fighting against before buying their items and can choose appropriately. At your level you will likely make lots of mistakes and be punished for them, and if you play Normal Blind Pick you may not know your matchup. In both cases Doran's won't save you; you need other starts like boots and 3 pots for escaping and healing, or armor and 5 pots for super hp regen.
For example, I play Olaf top with armor and 5 pots. Given the current meta I know I will be matched against an AD solo, so the armor will reduce damage they deal with a Doran's Blade. Also, I can use my 5 pots to heal a total of 750 hp, allowing me to ruthlessly Reckless Swing them. If they show up with a Doran's Blade or Shield, not only do they not reduce the damage from my Reckless Swings (True Damage), they have no way to quickly heal from the damage so they cannot contest me in lane. I will pound on them until they have to go back to base, giving me an advantage, or they will mope about in lane while I keep them from their creeps. Playing at my level this is a 90% success strategy. Playing Ranked against pros they will pick a champion who can lane against Olaf (say Riven, Cho' Gath, or Vladimir) and will probably beat me in lane.
Nonetheless, figure out if Doran's works for you. Watching streams will teach very little about playing at your level - the best way to learn is to try it!
Answer: Usually if you get ahead in gold,  buying a doran's blade will instantly make you stronger in that moment with that extra gold.  Which will help you in your lane at that exact moment.  Unlike items that cost the same as a doran's blade which will only be better when you make them into a complete late game item.
Answer: Buying a doran's blade is good when you get ahead like Jona52 said, It is also done to try and snowball and by getting that instant strength you can secure more kills and hopefully snowball yourself to victory.
Answer: It could also be if you are behind grab a couple dorans, they give great stats for being so cheap. You may end up stronger if you come back with a few dorans and your opponent is trying to build straight into his main build.
Answer: Doran's Blades offer every stat most bruisers deem valuable in the early laning phase: Health, Life Steal, and Attack Damage. The major drawback is these items do not build into anything late game, and your opponents will quickly out scale the early advantages this item offers. You should buy Doran's Blades Top Lane when you feel they will give you the necessary advantage to win the lane. Buy GP10 Items such as Heart of Gold or Philosopher's Stone to Catch up in lane you're losing instead of Doran's Blades.


How is the "Infinite Monkey Theorem" different to use than Genetic Programming to solve problems?

Question: This might be a little open ended, but I heard an explanation of this talk on how GP could be used to fix bugs, and I wonder: How does this differ from the infinite monkey theorem?
Answer: GP relies on "evolution", whereas the Infinite Monkey Theorem is just random chance.
In GP, you have one or more fitness indicators which are used to evaluate a generation of possible solutions to "breed" to create a new generation. Each one, more than likely, getting a better and better solution.
IMT has more to do with enough candidates that eventually every combination will occur.
Comment: At the very least, randomness takes second place to fitness in GP. One could theoretically seed a generation with non-random elements and breed with traits only from that population, thereby employing very little randomness. But certainly, it plays a role in both.
Comment: Got it, but still they have in common this trait of letting randomness take charge isn't ?
Comment: @OscarRyz: Many quicksort implementations "let randomness take charge" to pick a pivot. "Using randomness" doesn't mean  "guessing blindly"
Answer: The thing about monkeys is most of them are terrible writers, which is why we would need an infinite number of them. Your infinite monkeys will indeed produce some  great literary works (all of them in fact), however they will also produce an awful lot of crap (both literal and figurative). Using a genetic algorithm instead will hopefully let us produce some great literary works while keeping the crap to a minimum.
We first take a (relatively) large number of monkeys distributed among various traits (perhaps hair color, tail length, or how often they throw poop at you). Then we put them all in a cage so they can reproduce. Eventually they will reproduce so much that there are more offspring than you originally had. These new monkeys are each some random combination of monkeys from previous generations. We'll also expose the monkeys to some mild to moderate radiation to add a bit more randomness for good measure.
Now that we've got a new generation of monkeys it is time to put them to the test. Give each of them a pen and paper and tell them to write you a story. Once they've finished read through their stories and keep the monkeys who produced the "best" stories and sell the rest to the circus. Continue this breeding and pruning process for several million years and you should end up with a group of super monkeys that can consistently churn out literary classics without all the crap your infinite monkeys would produce.
There is a lot of randomness here (depending on how much radiation you used) but by selecting only the best monkeys to continue on at each generation the randomness will hopefully converge on the solution you are looking for without having to deal with an infinite amount of monkeys. It's true that an infinite amount of monkeys would give you the answer you want, but then you'd need an infinite amount of time to wade through their infinite amount of crap as well.
Answer: The infinite monkey theorem relies on the vastness of an infinite number of anything. An infinite number of monkeys bashing at keyboards randomly will instantaneously generate not only Shakespeare but every work ever written and every work ever to be written an infinite number of times. Including what the monkeys just typed. (How does a set contain itself you ask? It's infinite).
Genetic programming takes a large number of workers (far less than infinite) and selects the best candidates based on the fitness of their output. These workers are then mutated and allowed to run again the survivors of the next generation selected based on fitness.
Interestingly enough there is an IMT simulator that uses genetic programming to get better and better breeds of monkeys each generation. After running for 10k generations it could output the first 18 lines of Hamlet from what I remembered.
Answer: Another way of looking at it is in terms of probability. Say we have a space X of configurations and a function for evaluating how good those configurations are, f. To find good solutions, elements in X that have a high value f, we need to find a way of sampling X. Two strategies for sampling the space are the Infinite Monkey (IM) and Genetic Programming (GP).
The difference is in how X is sampled. In the IM strategy, the sampling is completely uniform. In Genetic Programming, an initial set of points are taken uniformly, but then the various hills and valleys of fitness (according to f) are explored from there.


What should I call an n>4 dimensional Minkowski metric?

Question: I am manipulating an $nxn$ metric where $n$ is often $> 4$, depending on the model.  The $00$ component is always tau*constant, as in the Minkowski metric, but the signs on all components might be + or - , depending on the model.  (I am not trying to describe physics with this metric).  Can I call this metric a Minkowski metric?  Or what should I call it?
Answer: Just state that pseudo-something metric via reference to its signature $(p,q)$.
http://en.wikipedia.org/wiki/Generalized_orthogonal_group
That link should also answer your other question, I think you could delete it or add it to this one.

The 00 component is always tau*constant, as in the Minkowski metric

The metric component (in contrast to the signature) are coordinate system dependend, so this statement is not really true. But even what you intended to say seem strage: in a homogenous space, why would the metric component want to grow with an affine paramert like that?
Answer: If the coordinates are cover your space, are real, and there no identifications or other topology-changing shenanigans, then this is a pseudo-Euclidean space. That is the proper generalization of Minkowski space with different signatures.
If the coordinates are local, then pseudo-Riemannian. This allows curvature or different topologies, but still requires the signature (num. of positive and negative components) to be the same throughout the space. Additionally, the specific case of signature $(1,n)$ or $(n,1)$ is called Lorentzian, though having a Lorentzian metric only implies that the space/manifold is pseudo-Riemannian and not necessarily pseudo-Euclidean.

The $00$ component is always tau*constant, as in the Minkowski metric, but the signs on all components might be + or - , depending on the model.

I'm confused about what that means, but it sounds like you just want coordinates in which the metric is diagonal. You could just say that, or state that the coordinate basis is orthogonal. If $\pm 1$, an orthonormal basis. It's up to you to make the $00$ component more special than that.


What are the kernel, the "GNU tools and utilities", the shell and the Window Manager?

Question: Among the many components of a Linux system, I find myself confused about what exactly is the kernel or what is GNU's part. I understand some basic concepts of this, but where is the line between a shell and the Window Manager?
Answer: Kernel
The kernel manages resources. Resources include processor time, memory, and peripherals. It does this by directly communicating with the resources and exposing an interface to userspace.
Userspace Tools (sometimes includes GNU tools and utilities)
The Userspace Tools include basic utilities like ls, cat, dd, ln, mount, etc. They allow a user to work with resources that the kernel provides. Linux (as opposed to BSD, OSX, and other Unices) is the primary user of the GNU tools, but not even all Linux systems use these; an alternate set of tools for Linux is provided by Busybox.
Shell
The shell provides the environment that allows the user to use the Userspace Tools. Example shells include bash, ksn, zsh, and fish. They typically provide a prompt at which the user can enter commands that launch the userspace tools.
Window Manager
This is a much higher layer, there usually exists a display server, which is responsible for managing graphical, audio, and I/O resources, and providing an interface to higher-level tools. Usually, a display manager is the layer above the display server and can provide things like user login management, and session management. Above that is typically a window manager. The window manager provides regions in which applications can render their content, it also allows the user to interact with these regions by moving, resizing, and reordering them.
Answer: If you're using 'bash' as your shell, that's a GNU utility.  The 'coreutils' package on your system contains GNU software, things like mv, ls, rm, etc.
The Kernel is not something you interact with directly, but through other software on your system.  To be very general in definition, a kernel is provides a means for software to interact with the hardware on your system, by reading in your key presses and mouse movement, reading and writing data to your disks, and scheduling and performing the computation from software running on your computer. There are a lot of details I'm ignoring/glossing over, you might benefit from reading the Kernel Wikipedia page.
Your window manager is most likely not GNU software, but from other software projects (Gnome, KDE, XFCE, etc).  However, they all rely on GNU software to run, using the GNU C Library (glibc) and the GNU Compiler collection (gcc) for example.  Also, much of the software on your system is licensed with the GNU General Public License, or the GPL, so you're benefiting from GNU's license.


limsup and liminf for a sequence of sets

Question: how does limsup and liminf for a sequence of sets, apply to probability theory. any real world examples would be much appreciated
Comment: As written, this question is too vague.  What exactly do you have in mind?
Comment: See http://mathoverflow.net/howtoask for some hints on how to turn this into a real question :)
Comment: Douglas Zare said on meta, "if you have gone through the http://en.wikipedia.org/wiki/Borel-Cantelli_lemma under the notation usually used, then you should recognize what the questioner meant, which is why the question got detailed answers even though it looks close to meaningless to some." (http://tea.mathoverflow.net/discussion/216) It looks like the question is not as vague as I thought it was, so I'm voting to reopen. I still would prefer that the question defined its terms and asked something more precise. It wouldn't have been hard to make the question clearly meaningful.
Comment: I agree with Qiaochu and Mariano, so I'm voting to close. I'm happy to reopen the question if it is edited to be more focused (though I guess that's unlikely since there's already an accepted answer).
Answer: For a sequence of subsets $A_n$ of a set $X$, the $\limsup A_n$ $= \cap_{N=1}^\infty ( \cup_{n\ge N} A_n )$ and $\liminf A_n$ $= \cup_{N=1}^\infty (\cap_{n \ge N} A_n)$.
If $ x \in \limsup A_n$ then $x$ is in all of the $\cup_{n\ge N} A_n$,  which means no matter how large you pick $N$ you will find an $A_n$ with $n>N$ of which $x$ is a member. Thus members of $\limsup A_n$ are those elements of $X$ that are members of infinitely many of the $A_n$'s. If $A_n$ are thought of as events (in the sense of probability) $\limsup A_n$ will be another event. It corresponds exactly to the occurance of infinitely many of the $A_n$'s. This is why $\limsup A_n$ is sometimes written $x \in A_n$ infinitely often.
Similarly, if $x\in \liminf A_n$ then $x$ is in one of $\cap_{n\ge N} A_n$, which means $x \in A_n$ for all $n > N$. Thus, for $x$ to be in the $\liminf$, it must be in all of the $A_n$, with finitely many exceptions. This is how the phrase "ultimately all of them" comes up.
Both of these operations, similar to their counterparts in metric spaces, concern the tail of the sequence $\{A_n\}$. I.e., neither changes if an initial portion of the sequence is truncated. As a previous response pointed out, often the sets $A_n$ are defined to track the deviation of a sequence of random variables from a candidate limit by setting $A_n = \{x: |Y_n(x) -Y(x)| \ge \epsilon\}$.  The members of $\limsup A_n$ then  represents those sequences that every now and then deviate $\epsilon$ away from $Y(x)$, which is solely determined by the tail of the sequence $Y_n$.
Here is a conceptual game that can be partially understood using these concepts: We have a deck of cards, on the face of each card an integer is printed; thus the cards are $\{1,2,3...\}.$ At the nth round of this game, the first $n^2$ cards are taken, they are shuffled. You pick one of them. If your pick is 1, you win that round. Let $A_n$ denote the event that you win the nth round. The complement $A_n^c$ of $A_n$ will represent that you lose the $n^{th}$ round. The event  $\limsup A_n$ represents those scenarios in which you win infinitely many rounds. The complement of this event is $\liminf A_n^c$, and this represents those scenarios in which you ultimately lose all of the rounds. By the Borel Cantelli Lemma $P(\limsup A_n)$ $=0$ or equivalently $P(\liminf A_n^c)=1$. Thus, a player of this game will deterministically experience that there comes a time, after which he never wins.
Answer: As Johannes stated, the Borel-Cantelli lemmas (there are two) are the primary way in which these quantities (referred to as "infinitely often" and "almost always") appear.
The most common use is to prove things about limits of random variables.  To see why this is the case, suppose you can show that, for any $\epsilon > 0$,
$$
P([|X_n| > \epsilon]\textrm{ i.o.}) = 0.
$$
(To show this with the first Borel-Cantelli lemma, you would establish $\sum_n P([|X_n| > \epsilon]) < \infty$.)  From here, it follows that $P([\lim X_n = 0]) = 1$, because
$$
P([\lim X_n = 0]) = P(\cap_i \cup_N \cap_{n\geq N} [|X_n| > 1/i]) =: P(A)
$$
by definition of limit, but
$$
P(A^c)
=1-P(\cup_i \cap_N \cup_{n\geq N} [|X_n| \leq 1/i])
\geq 1- \sum_i P([|X_n| > \epsilon]\textrm{ i.o.}) = 1,
$$
where the union bound (subadditivity) and definition of infinitely often were employed.
Note that i worked out a bunch of symbols to make sure the math was correct, but you can see it in words: if, for every $\epsilon >0$, you have the property that probability of
infinitely many of your random variables exceeding $\epsilon$ is zero, then it is intuitive that the limit of this sequence is 0 with probability 1.
To get a feel for more details (and the relationship to specific probabilistic quantities), maybe try using this technique to prove certain limiting properties of certain sequences of random variables (any probability textbook will have many, for instance the excellent book by Resnick).
I'll also add that you can prove a weakened form of the SLLN (weakened means you need some extra assumptions on which moments are finite) using Chebyshev's inequality and the limiting technique above.  As you can guess, Chebyshev allows you to say something of the form $\sum_n P([|X_n| > \epsilon) < \infty$, where $X_n$ is something fancier as needed for the SLLN (a normalized sum).
Comment: You claimed $P(A)=1$, but you proved $P(A^c)=1$, which is self contradictory.
Answer: What about something like $A_1\subseteq A_2\subseteq A_3\subseteq\ldots \implies \limsup A_n=\liminf A_n=\bigcup\limits_n A_n$ ?
If these sets are measurable sets in a (finite) measure space $(\mathcal{A},\mu)$, then $\liminf\limits_{m\to\infty} \mu(A_m) \geq \mu(\liminf A_m)$ (and $\limsup\limits_{m\to\infty} \mu(A_m) \leq \mu(\limsup A_m)$). Is that "application" enough?
EDIT: The Borel–Cantelli lemma is another application.
Answer: Here's another simple example, in a similar vein as has2's above. Let $X_n$ be a sequence of independent, identically-distributed exponential variables, i.e., $$\mathbb P(X_n > u) = e^{-\lambda u},$$ for some real $\lambda > 0$.  Let $E_n$ be the event that $X_n > n$, and let $E = \limsup E_n$, that is, the event $E$ occurs if there's an infinite (random) subsequence $n_k$ such that $X_{n_k} > n_k$.
We compute $$\sum \mathbb P(E_n) = \sum e^{-\lambda n} < \infty,$$ thus by the Borel-Cantelli lemma, $E$ has probability zero.  With probability one, there exists a (random) number $N$ such that for all $n \ge N$, $X_n \le n$.
Let's analyze this graphically.  Make a plot with the horizontal axis representing time $n$, and the vertical axis $x = X_n$.  Draw the line $x = n$.  For small times $n$, these random points might jump above the line $x = n$.  But the argument above shows that there is some (random) time $N$ after which the points $X_n$ all lie below the line $x = n$.


How do you observe body language and facial expressions in user testing?

Question: When user testing how do you record positive or negative body language? Do you use observed shifts in body language or facial expressions to consciously probe further about what the user thinks or feels about the product or task they are completing?
Comment: Anybody seen this http://www.imdb.com/title/tt1235099/ ? if half of what's there is true it's just awesome. I'd like to read some things on human gestures and face expressions.
Answer: With 'picture in picture' video (so its synched to what's happening on screen).
Being sensitive to body language is part of normal human empathy.
A good facilitator will pick up on this along with the many other clues and will probe if the user is stressed / happy / stuck.
Comment: Have learned it's important to be recording sound, not just video and/or screen recording.  We mark sound moments on the video frames (recorded at a lower frame rate on purpose) and then look at these moments of expression and what user and mouse movements are happening at the time. My old boss called these sound-expressions.
Comment: What do you do to use these clues to enhance your testing? Do you have any special means to record changes to review the footage later?
Comment: Yes you want the audio recording with the video, to capture the  'Thinking Aloud'.
Answer: For recording body language during usability testing sessions I've found the behaviors listed in this coding form from measuring UX (pdf) quite useful. Things like frowning, fidgeting, or leaning in close to the screen are often as meaningful as verbal remarks.
Observing body language and facial expressions requires focused attention, it is really easy to miss a frown or a quick smile. If you have the luxury of having an extra observer present, they can mark occurring behaviors and expressions during the test. The facilitator already has enough to do during the test, but it can be helpful when he is alert to nonverbal signs.
Why is this useful? When you're not just searching for issues, but also trying to achieve a particular emotional experience, statements like 'most users reacted to this page with surprise' can be quite valuable. Besides that, video recordings of nonverbal behavior work wonders in selling/presenting the results of your user testing: showing angry and frustrated reactions to an issue really helps in getting the message across to the stakeholders.
Answer: I'm always wary of my own amateur psychology skills when it comes to interpreting facial expression and body language. I try to use these signs as a guide that something needs further exploration, instead of trying to 'read' them.
Comment: If you get along fine in the normal day to day social world you're probably very good at interpreting facial expression and body language Ali.  The difficult bit is being able to ask questions to get to the bottom of WHY they're expressing the emotion.
Answer: I would be careful about making too many judgements based on body language unless you have experience in this.  In analysing interviews there are various techniques you can use, such as counting the frequency of certain gestures or facial expressions, but you have to be sure you are making the right interpretation and be consistent on what consitutes a certain gesture.
Apart from for very strong expressions/body language I wouldn't record them when analysing the video, but they can be used as a guide as to when the facilitator should interact with the user during the session.
Comment: ... but they can be used as a guide as to when the facilitator should interact with the user during the session. .............Exactly.
Answer: Non-verbal reactions help you contextualize verbal feedback. They also help you direct the user's discussion of the system under test. Alone, non-verbal signals are very easy to misinterpret, which is why you should follow up with the user to understand what is going on.
It is very powerful to name the behavior, and ask the user to expand. Just give them enough conversational space to disagree with your observation if they need to: "It looked like you might have grimaced there. Were you reacting to something?" "Oh, I wasn't grimacing. [grimace] It's just that this scroll bar is driving me nuts..."
I generally don't write them down specifically--they provide connotation to other notes. But if I were being a pure observer, rather than the facilitator (and therefore unable to ask follow-up questions), I would write down my impression but flag it as interpretation. "User seemed to be confused by dialog box." "User hesitated and grimaced when asked to sort items."


What could be causing this drop in water pressure?

Question: I have a deep drilled well with supply lines split to feed the house and livestock watering respectively. The flow to the livestock line remains constant regardless of water usage in the house. But with everything turned off in the house except one faucet, when a toilet is flushed the flow from the faucet reduces to a trickle. Pressure at the well remains at 45 to 50 lbs. What's up? Also, whenever lightning strikes nearby, I get mud in house water. I'm perplexed.
Comment: Is this a new problem, or has it always been this way? What size pipes do you have in the house, particularly the main branch?
Comment: Are you sure it's lightning strikes, or perhaps just heavy rain? Surface water getting into your well is a serious concern.
Comment: Where is your pressure tank or do you have multiple pressure tanks?
Answer: My guess is there is a restriction in the line going to the house, with only enough getting through to feed one thing, either the toilet or the faucet. And since the toilet is probably drawing the water first before the faucet, it goes there.
I agree that it is more likely just heavy rain that is causing mud in your water. However, surface water getting into your water supply is bad news. You should consider adding filters to clean up the water supplied to the house. I'd guess a chlorine injector to kill any bacteria in the water, a tank to give the chlorine some time to do its job and let mud settle out, coupled with a filter that can take the remaining mud and chlorine out.


Will it confuse my son if I try to teach him 3 languages, two of which are very close to each other (Russian and Ukrainian)?

Question: I know Russian, Ukrainian and English, my husband knows only English. We are going to teach our son Russian besides English (English is a dominant language where we live). But I wonder would it be worth the effort to try to teach him Ukrainian as well?
I have read articles on multilingual kids, but all the languages that they are learning are not similar. Where Russian and Ukrainian are different languages, but are closely related to each other.
I am afraid that my son (9 months old now) will confuse these two languages. I understand that there may be some confusion with either languages. But I would not like him to eventually be speaking neither proper Russian or Ukrainian but Russian-Ukrainian dialect.
Theoretically it should not be difficult for him to pick up Ukrainian when he knows Russian.
Are there any parents that are raising trilingual kids with two similar languages? And if there are, what are you doing to teach them both languages.
I was thinking of using one parent - one language method (or in my case mom - two languages and dad - one language). But I was going to switch languages (Russian and Ukrainian) every other day. It will also be more effort from my side to create Ukrainian environment around him. As there are no Ukrainian speaking playgroups where we live and I do not know anyone who speaks Ukrainian.
Answer: I had the same question for my pediatrician.  He stated that children typically take 18 to months to tie together 2 or more words.  When learning two languages children usually take a few more months but can tie together 2 words in both languages.  I told them that we plan to teach the baby 4+ languages and he said they wouldn't become confused and now is the best time to do it.
Answer:
I was thinking of using one parent - one language method (or in my case mom - two languages and dad - one language). But I was going to switch languages (Russian and Ukrainian) every other day.

My gut feeling is that this would just confuse him. IMHO it is better to stick with one language per person, for at least the first few years.

It will also be more effort from my side to create Ukrainian environment around him. As there are no Ukrainian speaking playgroups where we live and I do not know anyone who speaks Ukrainian.

That is the bigger problem. If you are the only one to speak Ukrainian with, it will require an extra effort from you to keep up the Ukrainian language environment on top of the Russian one. And as soon as you stop doing that, his Ukrainian knowledge will fade away. (Of course it may be refreshed sometime later in his life, if he gets into a proper Ukrainian environment... but then again, as you note, he will be able to learn Ukrainian solely based on his Russian as well).
Assuming there are enough Russian speaking families around to maintain a steady Russian language environment, I would focus on teaching Russian to him, and - depending on how things go - introduce Ukrainian a few years later.
Answer: I live in Indonesia and I have a son who is 15 months old. My native language is English but I can speak Indonesian and Javanese too (the local language here which is pretty close to Indonesian). His dad is Indonesian and speaks all three languages also but the grammar in English is not perfect. The majority of the other people around him speak Indonesian and Javanese except a few of my expat friends but he doesn't meet them that often. He uttered his first words at 12 months and now at 15 months is speaking in all three languages. He can't make sentences as such but can get his message across. For example the other day he heard the ice cream man outside the house and shouted to me 'Ice, ice, ice, shoes ON! OUT OUT!' He can say a lot in Indonesian and Javanese too. He understands all three also. He will easily follow instructions in any language that you use.
What I worry about your case is that there are no other sources of Ukrainian which is what I think will make your case more difficult but not impossible.
What I think is use your intuition with your own child. If you feel using all the languages is working out as a lot of effort and taking time away from just enjoying the time with your child and teaching him English and Russian then just leave it for now. If it feels easy and natural for you then go for it. Good Luck!
Answer: There are entire countries where language switching is the norm, i.e. from sentence to sentence you switch among two or more languages. They do not get confused.  People who are monolingual think speaking anything but one language is confusing because high school French was confusing for them.
Children have been reported to prefer to speak one particular language to a particular person, but I think that happens after that persons for a long time speaks only, say German and then switches to English, which some children don't like the abrupt change in habits (even though they may be fluent in both)
I speak Russian as a 2nd language, I can assure you that Russian and Ukrainian are only similar in the same way that Dutch and English are similar. There is no way that one would mistake one for the other, neither as a learner, nor as fluent speaker.
One parent two languages systems do happen, the recommended advice is to keep the domains where you use one or the other separate (eg. one language for outside the house, one language inside the house), or digloss (switch back and forth between the two-- but this option isn't available for all pairs of languages because some language communities don't tolerate dilogsia, some language communities demand it!)
Comment: Switzerland is a good example
Answer: For parents who are multilingual, speaking multiple languages does not confuse young children. They may use multiple languages to speak a sentence. Often their parents do as well. Generally, when they have words in one language but not the other they use the word they have. What may appear to be confusion is likely the same struggle with language acquisition children have in one language. Bilingualism tends to delay mastery of some components of each language; again likely due to the amount of language acquisition being accomplished rather than confusion between languages. Speak all the languages that you feel are important for your family to use; are important to your child's future. You will find it very difficult and possibly heartbreaking trying to teach a teenager a language that does not seem relevant to their lives.
To hedge my recommendations; most of the evidence is from bilingual homes but should apply to multilingual. Also, it should be pointed out that I am assuming that the parents are fluent in the languages they use.
Some articles:
Parental Language Mixing
Early Bilingual Development
Answer: If you can keep it up, and if you can avoid the mix of Russian and Ukrainian known as "суржик" (spoken also in Kiev) not really understandable by stalwart knowers of some one language only, it may help in future life: many European Slavic languages share simlariries to one or another of those, so knowing both can make Czech, Polish, Croatian, Slovak, Slovenian and many others simpler to understand and converse in. You never know what the future would really bring so it helps to have options. As a saying goes, knowing at least 3 distinct languages from the same family almost guarantees easy adaptation to others in it.
And let me assure you, languages in even the same family (Slavic, Romanic, etc.) are substantially different to not even feel or sound the same.
Although yes, it is an effort to keep them apart and think in some metalanguage that maps from and into anything =)


Cardio ideas for someone with Plantar fasciitis

Question: I've had plantar fasciitis for awhile now.  I'm seeing my doc, I wear orthotics and I stretch in the mornings.  I do personal training, 2-3 times a week, too.  But I really need to start doing more cardio, but it's hard since I have Plantar fasciitis.  I'm not a good swimmer, and I don't think I will ever be able to run, but my lack of cardio fitness is hampering my personal training (I become winded easily).  Does anyone have any ideas for good cardio workouts that aren't so hard on the feet?
Comment: Did you get plantar fasciitis from running? Also no pain-no gain, so even though you may suck at swimming, that may make is a good workout :-) Also, does the plantar fasciitis hurt when cycling/spinning?
Comment: I get plantar fasciitis from walking.  I walk at least a mile a day just to get to here and there.  Running bothers my IT band & my plantar fascittis too.  I haven't tried cycling/spinning - maybe I should try that.
Answer: Ironically, no pain, no gain. So any workout you're bad at generally becomes a great cardio workout. As Carl Foster, a professor from the university of Wisconsin, once said during a presentation:

When you want to work out, don't go cycling on this:

Instead use this:

The point is, working out isn't about how fast your bike goes. Its about how fast your heart is racing and your lungs are ventilating. So when you say you're a poor swimmer, it might actually be a decent workout, since its guaranteed to cost you a lot of energy.
As for a good workout for plantar fasciitis, you could try cycling as this is said to be a great rehabilitation exercise when you have a plantar fasciitis. Other alternatives would be going to the gym or something like rowing.
Just a small note: I do find it strange your plantar fasciitis keeps recurring, even when walking normally. Besides if the orthotics don't take away the problem, don't forget to go see the specialist again, because it might not be working the right way.
Comment: The seat on that second bike would be likely to chafe a lot on long rides.
Comment: @freiheit this is true, put the point is the analogy to swimming inefficiently is good exercise
Answer: Some ideas other than cycling:

Swimming
Elliptical
Rowing
Step Machine

Avoid high-impact exercises and no jumping!
Comment: For how long? Is there a way to know or test that you can return to running and when to return to sprints?
Answer: I found that i needed to rest (take a break from running) for much longer than i wanted.  I would quit for about a week or two and the pain went away so i started running again.  Days later, it was back.  So....give yourself a good long break for the tendon to completely heal.  Then, after a few months, slowly start back.  Also, stretching and good shoes are essential.  I was pain free for years and then did some sprinting in bad shoes and was lazy about stretching and now I'm back to square one.  I've also had good luck with ice and orthodics.
Comment: oh yes, I also noticed the problem is worse when i'm carrying too much weight.  Unfortunately, stopping exercise doesn't really help the weight thing so am forced to diet.  :<
Answer: I'm currently recovering from the same condition, which I've been dealing with for over a year now. I got orthotics two months ago, and they are helping immensely. If you're not seeing progress with them then definitely see your doctor again to see if the fit needs to be adjusted. Your doctor should have already been scheduling you for regular checks for this, at least early on in using them.
Also, in addition to stretching in the mornings, you might want to try doing some calf stretches at night before bed as well. It can help to prevent your leg from stiffening up in your sleep, which can put strain on the tissue.
Most of the major exercises have been covered (my first thoughts were cycling, rowing, and swimming). Rock climbing is another possibility as long as your careful about how you use your feet - no jarring motions.
You might also consider turning some of your resistance workouts into a combination or cardio and strength training. Use lighter weights with a lot of reps or do calisthenic types of exercises (push-ups, pull-ups, etc.). Do bursts with brief rests in between and concentrate on keeping your heart rate in the target zone. You might not get optimum strength results, but I find these workouts to be a fun change of pace for me.
Good luck!
Comment: Thanks for the suggestion about changing the resistance workouts.  I'll give that one a try too!
Answer: Never walk barefoot. Never. My Dr. made me purchase some padded sandals on day 1. I brought my shoes to my 2nd visit and was told to get rid of the cheap ones... your foot and arch need support (ECCO, New Balance, Ryders, etc). Replace them anually and replece the orthotic inserts quarterly. Stretch before getting out of bed (mornings or night runs to the b-room, etc). Taping helped me a lot, too.
For cardio exercise, I am using a stationary bike.
Comment: Hi @Kyle, it's good to see your suggestions on shoes for someone with plantar fasciitis. Can you elaborate more on what types of cardio workouts the asker can do given the condition?
Answer: Perhaps your plantar fasciitis is caused by over training. The suffix "-itis" means inflammation and inflammation is the result of too much stress. Large bouts of cardio may be the cause for your plantar fascitis. Our body is not designed to do cardio for hours on end, 5 days a week unless your an endurance athlete with genetic gifts.
With this in mind you may benefit from a period of rest to reduce inflammation in your feet and then begin a cardio routine that achieves a high VO2 (I.e 100-125% of your VO2 max) for short durations. Interval training such as this allows us to accomplish the same, if not greater fitness levels, while reducing our overuse of joints and muscles from tedious, submaximal exercise.
Answer: You can raise your heart rate lifting heavy weights. For most people, their bodies are heavy weights, so bar calisthenics could be a good option - it keeps you off your feet most of the time but really works the rest of your body. I know it's not what most people think of when they say cardio, but exercise works your heart, anything you do that takes effort will be good for you.


Can't mount two external hard drives at the same time

Question: This whole problem began a few months back when I tried to transfer data from my external hdd (formatted to NTFS) to a computer using Windows 7. While in Ubuntu, there is about 1 TB worth of data (important things which I would rather not lose), but when I tried to access those files from Windows, they didn't show up
After lots of Googling and trying things, I did the following using a spare external HDD that I had (same manufacturer, same capacity) .

Formatted the spare drive to ext 4
Transferred every file from old drive to spare drive.
Reformatted old drive to NTFS using gparted
Transferred some files on to the old drive to test if it works on Windows, and it did.

Now the problem is, when I try plugging the old drive again in Ubuntu, it doesn't mount. I noticed this happens when the spare drive is already mounted. I have tried formatting the old drive to Ext4, FAT32 and again in NTFS but no luck so far.
I get this error message when trying to mount the spare drive with the old drive already mounted and a similar one when the drives are reversed:
Error mounting: mount exited with exit code 1: helper failed with:
mount: only root can mount /dev/sdc1 on /media/Seagate External

This is the result of trying to mount the drive via the terminal:
sebastian@ubuntu:~$ sudo mount /dev/sdc1
[sudo] password for sebastian:
ntfs-3g: Failed to access volume '/dev/sdc1': No such file or directory

ntfs-3g 2012.1.15AR.1 external FUSE 28 - Third Generation NTFS Driver
Configuration type 7, XATTRS are on, POSIX ACLS are on

Copyright (C) 2005-2007 Yura Pakhuchiy
Copyright (C) 2006-2009 Szabolcs Szakacsits
Copyright (C) 2007-2011 Jean-Pierre Andre
Copyright (C) 2009 Erik Larsson

Usage: ntfs-3g [-o option[,...]] <device|image_file> <mount_point>

Options: ro (read-only mount), remove_hiberfile, uid=, gid=,
umask=, fmask=, dmask=, streams_interface=.
Please see the details in the manual (type: man ntfs-3g).

Example: ntfs-3g /dev/sda1 /mnt/windows

News, support and information: http://tuxera.com
sebastian@ubuntu:~$ sudo mount /dev/sdd1
The disk contains an unclean file system (0, 0).
The file system wasn't safely closed on Windows. Fixing.
fuse: failed to access mountpoint /media/Seagate External_: No such file or directory

This is the fstab, if it makes a difference:
# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>

proc    /proc   proc    nodev,noexec,nosuid 0   0
/dev/sdd1   /media/Seagate\040External_ ntfs-3g defaults,nosuid,nodev,locale=en_US.UTF-8    0   0
/dev/sdc1   /media/Seagate\040External  ntfs-3g defaults,nosuid,nodev,locale=en_US.UTF-8    0   0
/dev/sdc1   /media/sdc1 ntfs-3g defaults,locale=en_US.UTF-8 0   0
/dev/sdc2   /media/sdc2 ext4    defaults    0   0
/host/ubuntu/disks/root.disk    /   ext4    loop,errors=remount-ro  0   1
/host/ubuntu/disks/swap.disk    none    swap    loop,sw 0   0

I should also mention that the old drive originally had a second partition of ~100 GB with nothing on it.
Any insights would be appreciated.
Answer: Your fstab entries are messed up.  You are trying to mount the same device in two different places, and one of them with two different filesystems.  You shouldn't have any fstab entries at all for external media; they will be automatically mounted when inserted.


How can I make Dominion play better with 5+ players?

Question: I just got Intrigue, and it seems cool that it opens up the game to 5 or 6 players. However, the common consensus seems to be that its possible, but not recommended. Is there anything I can do to make Dominion play better with 5 or 6 people?
Answer: The biggest problem with extra players that I usually see is down-time. Dominion is partially a group solitaire game. There is some interaction between players with attack cards, but otherwise your opponents turns won't matter a lot besides keeping an idea on what piles are low and the game end. I find with 5 the main problem is "I know what I'm going to do, I just have to wait through 3 more people's turns to do it". You also might want to tweak the number of kingdom card piles to somewhere between 11 and 13.
The first and easiest thing you can do is lessen the cards that take longer to resolve. Spy, Throne room, Adventurer, Contraband, Counting House, Possession, and many others tend to make turns take a little longer. This doesn't mean that they are bad in any way, it just means if you are worried about long down-times with 5 or 6 people you might want to forgo them. Removing certain cards may annoy hardcore players who want a truly random layout, but my games usually aren't super serious and its worth it to fit in the extra person.
Another thing you can do if you are adventurous with 6 is play 3 teams of 2. Turns pass from one team to another. Both members of that team take their turns at the same time and have totally separate decks. Their attack cards only affect the players on the other teams. It helps to use attack cards that don't depend on order very much in case you both attack. What do you do if one of you plays a spy and the other a thief? What order do they go in? Instead of trying to make rules about this, just use attacks that don't clash with others too easily, like militia and witch. The team mechanism is mainly to allow some simultaneous turns; you can play as a team and do some minor collaboration, like who should buy what or who should focus on attacks vs. victory points, or still make it every man for themselves and have the player with the most victory points win.
Answer: Not forever, but for a while at least, don't play with the cards that require a player to make a choice for every other player.  I'm thinking of cards like the Spy, where you get to choose whether or not to trash the top card of each player's deck.
I suggest this because, if your group is inexperienced at Dominion, this kind of thing can easily slow the game down to a crawl.  Personally I find that a lot of my Dominion actions are really simple things like "buy a Treasure" or "buy a Province".  It drives me crazy if I'm waiting 5 minutes between each move when I'm just autopiloting my strategy.
Once everyone is experienced at Dominion, of course, they can get their moves done quickly and efficiently, even if multiple additional actions and draws are involved.  As long as the game is going pretty much as fast as it can go, there are no grounds can complaint.  But until then, it can be really frustrating to be sitting around non-interactively for minutes on end waiting to play a move that requires no thought on your part anyway.  So, yes, that's my suggestion: phase the more complex and fiddly cards in gradually!
Answer: Whenever my group has 5 or 6 for Dominion, I try to split it into two groups, either 3+2 or 3+3. With Intrigue, there are enough basic Treasure, Victory, and Curses to go around. Then when both groups are finished, you can switch and play with the other Kingdom with no additional setup time; then compare notes as to how the different groups handled the different boards.
Answer: One suggestion I have is that, once someone finishes playing all their actions, have the next person start playing.  There is only one Treasure card that involves any other player doing anything, and that is Contraband, where the person to your left can name a card you cannot buy.
Having said that, if a player has a card that affects other players, they need to stop and wait for the other players to catch up.  Two non-attack cards this applies to are Masquerade and Vault.
If you're going to play an action that requires you to count cards (Counting House, Philosopher's Stone), count the cards in advance.  The only time you can't do this is if you have other actions that will affect the card count.  In the case of Philosopher's Stone, this is any card that causes you to draw cards (cards in your hand and in play are not counted by Philosopher's Stone).  For Counting House, this big one that affects this is Chancellor, as long as you have two or more actions this turn.
This next part wasn't really what you were asking for, but for each player over 4, you should add 3 Estates, 7 Coppers, 10 Curses, and 3 Provinces to the game.  The Estates and Coppers make sure these piles stay at their respective starting numbers despite the number of players (12 and 32 respectively), as there are cards that may or may not manipulate these piles.  Increasing the number of Curses and Provinces is mentioned in the Intrigue rulebook.


How to compute the alpha decay of a strategy?

Question: How can one compute the alpha decay of a systematic trading strategy?
Answer: The short answer (which represents one way of surely many ways to do it) is to watch the t-stat of a performance metric such as information coefficient vanish over time. IC is the correlation of predicted expected returns from your alpha strategy to the underlying benchmark.
Look at the expected returns your alpha strategy predicted over the past N time intervals and see how those predicted returns were correlated with the benchmark. This is the IC.
The crux of course is that you need to test if the IC is statistically different from zero or is just random noise. You would do this by computing the t-stat over time and watch it decay as the strategy you managed to build over hundreds of hours of research is unceremoniously drained of edge.
Comment: Agreed. Grinold & Kahn cover this in their text Active Portfolio Management, 2nd edition extensively.
Comment: Might want to look at different notions of correlation - spearman, kendall's tau. The pearson correlation is not as strong a measure of concordance as spearman for various reasons
Answer: You can come up with many specific answers depending on the application, such as high frequency vs. low frequency, or cross-sectional (e.g. single stock equity relative value) vs. time-series strategies (e.g. trading E-mini S&P 500) (strimp099's suggestion of using information coefficient is a good suggestion for equity relative value).  However, a general answer that is likely to at least give you some indication for any strategy is to look at the time series of returns over two adjacent periods and perform a t-test for difference in means.  If the later period has a statistically significantly lower mean return, then the alpha has likely decayed.  Measuring the precise degree of decay is going to be nearly impossible for anything but a relatively high frequency strategy with a very long time sample.
Answer: The blog post http://www.portfolioprobe.com/2011/11/30/alpha-decay-in-portfolios/ tells of one possible method:
Generate two sets of random portfolios.  Both sets satisfy your portfolio constraints, and one set is additionally constrained to have high expected returns.  You can now look at the distribution of the difference in returns for various time frames.


whitehead group of product of groups

Question: I am wondering is there a formula for the whitehead group of product of groups. In other words, if we know the whitehead group of two groups, are we able to calculate the whitehead group of their products. If not, is there a example such that the whitehead group of the product is nontrivial while the whitehead group of both groups vanishes.
Answer: This is a partial answer. Let $G$ be a group. Then by identifying $\mathbb{Z}G[t,t^{-1}]$ with $\mathbb{Z}[G\times\mathbb{Z}]$ and using Bass-Heller-Swan decomposition you will get
$K_1(\mathbb{Z}[G\times\mathbb{Z}])=K_1(\mathbb{Z}G)\oplus\tilde{K}_0(\mathbb{Z}G)\oplus NK_1(\mathbb{Z}G)^2$. Therefore
$Wh(G\times\mathbb{Z})=Wh(G)\oplus\tilde{K}_0(\mathbb{Z}G)\oplus NK_1(\mathbb{Z}G)^2$.
As for the example you are looking for, take $G=\mathbb{Z}/4\mathbb{Z}$ and $H=\mathbb{Z}^{3}$. The Whitehead group of these two groups vanishes but the Whitehead group of its product does not. The reason is that $G\times H$ is the fundamental group of $L\times T\ ^3$ where $L$ is a 3-dimensional lens space and $T\ ^3$ is a 3-dimensional torus. Farrell and Hsiang (F. T. Farrell and W. C. Hsiang, Bull. Amer. Math. Soc. Volume 73, Number 5 (1967), 741-744) proved that there is a non trivial h-cobordism with that space as one of its boundary components.
Answer: I just realized that the Farrell-Jones conjecture can be treated as a generalization of the Bass-Heller-swan theorem, hence can answer my question. Note that the conjecture has already been verified for a large class of groups.
Given two groups, $H$ and $G$, The Group Ring $\mathbb{Z} (H \times G)$ can be considered as $(\mathbb{Z}H)G$. Denote the Ring $\mathbb{Z}H$ as $R$, then the K-theoretic Farrell-Jones conjecture predicted the following assembly map is an isomorphism
$$ H_n^G(E_{\mathcal{VYC}}(G); \mathbf{K}_R) \rightarrow K_n(RG);$$
 where $E_{\mathcal{VYC}}(G)$ is the classifying of G respect to the family of virtually cyclic subgroups, $\mathbf{K}$ is the non-connective K-theory spectrum.
Basically, the conjecture says if we know the homology theory of $G$, the K-theory of $R$, then we know the K-theory of $RG$. But in order to calculate $K_1(RG)$, we definitely need a lot K-group information of $R$, not just $K_1(R)$.  So only known the whitehead group of $G$ and $H$ is not enough to recover $Wh(G\times H)$. This also explains why there exists two groups with trivial whitehead torsion while the whitehead torsion of their product is non-zero.

whitehead group of product of groups


Joel Test on careers.stackoverflow.com?

Question:
Possible Duplicate:
Where is the joel test on jobs.stackoverflow.com

How about giving all the employers using to careers.stackoverflow.com the opportunity to take the Joel Test? Or should they even be required to answer the 12 questions?
Comment: Opportunity or require?
Comment: +1 if it goes to "require" from "opportunity"
Comment: Disagree about the REQUIRE .. hopefully there will be jobs for things other than development.
Answer: What would be nice is if the employers had to fill out some sort of a bio about their company that you get to see when they contact you.  I agree this should include the Joel test, but I don't think it should be required, and here's why.  The test itself does seem to be a really good indicator as to the state of a company, but it's a really good indicator as to the competency of the management staff if they know what it is.  If you don't make it required, the companies which have their hr people searching the careers board, or have managers who you would rather stab your eye out with a fork than work for won't fill it out. They probably won't even know what it is.  It's like getting to ask a question before you even respond.  Something like this:
"Do you know who Joel Spolsky is?"(not whether if you agree with him).
"Who?"
FAIL!
I have a distinct feeling the board will get popular enough that companies will just sign up to the board, because some consulting firm charging them a lot of money said they can get hire good people from this board.  The companies where everyone asks, "Who's this Jeff Atwood guy, and why does he have this logo of someone with his hair sticking up? Does he have a bad hair stylist?  Is it a fashion thing?"  If you require it, most companies can stretch their response to be maybe a 6 or a 7 without outright lying (I was thinking of my last company which was no way near a place I would call good at software development).  That being said, if no one at the company knows the significance behind filling it out, that is a telling key.
Answer: If you look at jobs.stackoverflow.com right now, there are a bunch of employers who have filled out Joel Test scores, and it does make them look like more attractive places to work. For example, I've never heard of "Quantios" but if they have a 12 on the Joel Test they might be a good place to work.
So, on the whole, I think it would be valuable if the employers using our service had some way to self-declare their Joel Test score. If a programmer put up their CV and got a bunch of messages from employers, they might look at the ones with high Joel Test scores first. And it's a part of the general gist of careers.stackoverflow.com, which is, it's all about quality, not quantity: good jobs for good programmers.
Answer: I would like the ability for a candidate to add requirements to pass particular Joel Test questions. If the employer doesn't pass, don't list the CV. One of the benefits of the Joel Test is that it appears to encourages employers to admit some of their failings in order to show off some of their wins. "Do you do hallway usability testing?" Nobody cares. "Do you fix bugs before writing new code?" Nobody does. "Do programmers have quiet working conditions?" If they don't, stay the hell out of my face.
Answer: It should be required AND when we are contacted by the employers we should be given a list of questions from the test the employer did not pass.
Answer: It's featured on the job board, I assume it would be on careers.
Comment: Sigh...the delicate flowers of Stack Overflow strike again...
Comment: @stu How would you do mathematical induction then?
Comment: @Sam: Apparently that is the source. Movie is from 1995, and the bar (Billy the Bums) opened in ~1996.
Comment: I'm sorry I missed whatever it is these comments refer to. I do not follow them at all.
Comment: @dlamblin: smells of deleted comments, but with replies sticking there anyway...

Joel Test on careers.stackoverflow.com?


Can SharePoint timer jobs call SQL Server?

Question: I have created a console application that retrieves data from SQL Server 2008 into a SP 2010 portal. The account that it uses is a personal account that is part of an AD group that has been configured on SQL to have read only access to the data. As long as I execute it in the console application, it works fine. However, I created a timer job with the same SQL queries and deployed it to the server. I can execute the job and step through the code. No error is returned, but no records are retrieved from the SQL table using the identical code from the console application. I have checked to make sure that the farm account has been added to the AD group that is configured for read-only access to the db. I've set up a task to run the job and it's working OK, but I'm thinking that's probably not ideal. I've also set the trust level for the web app to "Full". Please let me know if there is some inherent limitation in using SQL components in SharePoint timer jobs.
Answer: Yea, all timer jobs run under your service account's identity, which may not be the same as the farm account.
I've had success adding an owstimer.exe.config file to the sharepointroot\bin folder and configure enterprise library on there.  That way I could easily output trace and other debug information.
Answer: Mike,
You didn't specifically mention it but I would be very wary of hitting any of the  SharePoint Databases directly - even as read only as this is not supported.
http://support.microsoft.com/kb/841057
I am aware there is one exception to this in SharePoint 2010 around usage logs,  but I can't find any official documentation to clarify this.
AndrewWoody
Comment: Woody - I was told in a briefing by MS last week that the logging database is totally open and we can do whatever we want to it, but I have yet to see this in print too.
Answer: I followed a very similar path in 2007.  In fact, that led to my first timer job.  I would concentrate on trying to validate the identity the timer job is running under and find a way to write out some diagnostic info.
It may also be worth trying to temporarily open up the sql permissions to validate if it is a permissions/identity issue or something else that might be preventing the results from being processed.


"practitioners' community" or "practitioners community"

Question: I would say the first is the correct one (with apostrophe), but I see the other one much more.
Don't know if it is relevant, but I'm a British English user.
Answer: Stan Rogers has got the right answer but the wrong reasoning.
practitioners' is correct because what's being refered to is their community, so there's a possessive 's to be added. But because the subject is already plural, the actual s doesn't get written. Nor, incidentally, does it get pronounced in this situation, but pronunciation of the possessive s is independent of whether it's written or not.
practitioner's applies with a single practitioner for anything of his, including his community
practitioners is invalid with no possessive apostrophe, because all you're left with is a plural noun. That can't be used as a modifier to anything, including communities. You can have a dog trainer, where the 'noun' dog modifies trainer. But you can't have a dogs trainer.
Comment: Your reasoning is *identical* to mine, it's merely phrased differently.
Answer: I haven't seen this specific phrase, so not sure if context would alter the question. Grammatically both can be correct.  You can have a community of practitioners that they themselves do not own, in which case the second choice would be correct.
Comment: So you're saying @Stan Rogers is wrong?
Comment: Well technically speaking I'm sure no practioners actually *own* any communities. They're probably what we in the UK call *General Practitioners* (i.e. - doctors working in their local surgey rather than within a hospital). Usually they're in *Group Practices* where several doctors serve the local community, in which case #1 applies. Sometimes there's only *one* GP, in which case he works in his own **Practitioner's Surgery**. OP's #2 is just plain wrong.
Answer: The ess-apostrophe version is correct if it is equivalent to community of practitioners or community to which the practitioners belong (and it's difficult for me to imagine how it wouldn't be with a plural practitioners unless the host sentence is very convoluted).
If it is equivalent to the community to which the practitioner belongs, then it would be practitioner's community.
I've tried to imagine a sentence where there would be no apostrophe, but everything I can think of would require a comma between practitioners and community.
Answer: Context is relevant. "practitioners community" means a community of practitioners, whereas "practitioners' community" means a specific community to which the practitioners belong, implying there may be multiple communities or a larger community beyond the one being discussed. The sentence structure and your intent should guide you to the correct usage.
I disagree with @FumbleFingers about the "dogs trainer". Just because it isn't contemporary language doesn't mean it is invalid. A "dog trainer" may work with a single dog at a time while a "dogs trainer" will work with a group. "dogs' trainer" would refer to a solitary trainer that worked with a specific group of dogs. Makes sense to me.
Answer: Both forms are grammatically correct.  The difference between them is that practitioners' is a possessive noun and practitioners is a plural noun modifier.  I found this exchange on plural noun modifiers that has some interesting quotes from Quirk et al., A Comprehensive Grammar of the English Language, Longman.
In short, the doubt about the validity of form #2 comes from a rule in the past that noun modifiers had to be singular (apple tree, vegetable soup, rubber chicken) but today this is not an absolute and there are many examples of plural noun modifiers in everyday use, for example, parts departments, schools superintendents and options markets.
Quirk lists the following situations where a plural modifier may be used:

the singular form might lead to ambiguity
  an Arts degree (a degree in the
  humanities) as opposed to an art
  degree (a degree in fine art)
there is no singular form of a noun (in pluralia tantum)
  a customs officer
there is a need to denote variety
  a soft drinks manufacturer [but] a
  car manufacturer
a topical issue comes forth, often in newspaper stories. Quirk cites
  examples of Watergate reporting from
  newspapers:
  the tapes issue
  the tapes compromise
  the Watergate tapes affair
  the White House tapes mystery and other examples, including jobs cut.


Is there a way to update your NetFlix queue to replace all DVDs with Blue-Ray where available?

Question: I just got a Blue-Ray player and am thinking of upgrading my NetFlix account to Blue-Ray. It looks like it has an option to automatically select the blue-ray option when you add new things to your queue, but is there any way to have it go through my existing (lengthy) queue and replace in blue-ray versions wherever they are available?
Answer: There is no readily available way to update your Netflix DVD queue on the Netflix site, other than the available controls (add, remove, change order and change star ratings).
However, using their API you could (conceivably) write a script that will manipulate your queue in any way you want. You can schedule it to run periodically to scan all the DVDs in your queue, find out if they have a BluRay version and if so, replace the two. Update: Netflix removed API support back in late 2014.
Answer: If I remember correctly, when you enable the Blu-ray option it will update the queue for you automatically.


Set different double click times for physical click and trackpad double-tap

Question: When clicking my trackpad physically, I want the double click speed to be as fast as possible. When using the tap-to-click feature, though, I want it to be a tiny bit slower. Is there any way to set this, either natively or with third party apps?
Answer: You can rule out SteerMouse, I just connected a second mouse and there is only one setting for double-click delay shown. Based on that I'm doubtful of USB Overdrive's claim:
"The USB Overdrive can easily handle several USB devices at once and can assign different settings to each one." - but it's probably worth a look!
I think ControllerMate could do it if the developer felt like it - it's a way more configurable approach and is flexible enough to build complex control schemes for HOTAS game controllers. You should register your interest in being able to control the Magic Trackpad with a quick email. I don't know for sure that ControllerMate can't do what you want, it all depends on whether its building block approach sees a "Source" for each mouse-like device or whether it just uses the kernel's mouse driver output and sees an aggregate of control input for the two devices. There is a time-limited trial available.


htaccess performance issues vs restarting the server

Question:  I usually use the server config file for settings that I would like to apply to my applications (at least in the development environment), and constantly have to re-start the server.
  I know that I cannot keep re-starting the server every time during production; my choice would have to be .htaccess files.
  My question is this: how much performance issue does using htaccess files cause? I understand that it depends on how many folders the request has to traverse to obtain the required file; so here's an example:
  If the request path is host/folder1/folder2/folder3/folder4/folder5/file_requested, and the htaccess is placed in the root folder, are we talking about a significantly, measurable performance issue, or something that can be ignored? I wouldn't want to restart the server every time I need changes to an application's configuration.
 Thanks.
Comment: what I am saying is do you have rewrite rules? like /about/ => /index.php?page=about. Does your update are for development purpose? my point is here you can use .htaccess at the beginning and then move them to the vhost once it's completed.
Comment: How often you reboot? What type of URLs you have?
Comment: Because I'm constantly trying out new features on each application I put on the server, a minimum of 4 times daily (although it's mostly on the development server; yet, I usually reboot about once a day once I apply the new settings. And I don't understand what you meant by type of URL)
Answer: Well, as mentioned by @Book of Zeus, this depends on how affecting are your rules.
.htaccess works with a hunting process, this means... suppose you have a file being accessed at
/var/www/foo/bar/baz/dir1/dir2/file.ext
Apache will first parse and identify if file or directory exists. Then it will check if there is any .htaccess file inside /var/www/foo/bar/baz/dir1/dir2/. If it matches, it processes and we are fine, if not, it will check the parent directory (/var/www/foo/bar/baz/dir1/) for a .htaccess and, if it encounters one, process the matching rules. If not, it proceeds to the parent and check... you got the pattern... until reach the root folder.
Summarizing, the closer to the target file the .htaccess is, higher the precedence in the hunting process.
In any case, my final suggestion is test it. Make some changes in the Apache configuration file, restart, and benchark it. Then rollback your changes a put them into a .htaccess files and run the same test. Check for response times and memory usage. Try to replicate your production load. This ca be your final silver bullet deciding which method you should adopt.
If this indicates you that changing Apache config and restart is really better, try to implement changes of the day all at once, in a nightly job run to minimize the prod impact.
PS: Apache comes with a program named "ab" - apache bench - in its default installation. You can use it to make your tests.


What's the difference between the different versions?

Question: My brother recently got me interested in Minecraft, and I'm having a lot of fun playing it. The thing is, I've only ever played the Beta version. After I first played it, I found a whole bunch of pictures and videos online with stuff that wasn't in the version I was playing. So I was wondering: What are the main differences between all the different versions of the game?
Answer: The differences are far too numerous to list here (Minecraft is still under heavy development), but the unofficial wiki has a detailed list of the significant changes in each release.
Roughly speaking, however, the different stages of development can be described as:

Classic: proof of concept
Indev: develop into a salable product
Infdev: infinite world generation
Alpha: downloadable client and offline play
Beta: content and polish
Answer: What you might have seen is someone playing with mods - extra code not written by Mojang - that allow players to do things not in the base game.
As Minecraft auto updates (you get prompted until you accept the update) you will always be playing the latest released version (even though it's still in Beta). This means that you can be sure that when playing multiplayer everyone is on the same version.
There have been removals of "stuff" but mostly it's tweaks to existing game play plus additions of new game play.
Comment: Good answer. Very few blocks are missing from Beta (sponge, blue flowers, some colours of wool). Some blocks are in Beta but are just very rare (e.g. clay, diamond). Everything else is either added in by a game mod, or is actually an existing block with custom texture pack.
Answer: Outside of various updates to the "Beta" version of Minecraft, there are two major versions of Minecraft at the moment.
Minecraft Beta, often called Alpha, or Survival in older videos, is the main game, where you enter an infinite world and explore, build, craft, and try to survive the night.  It's the main focus of development by Mojang AB, and, for the most part, has the most features.  The multiplayer version of this is often called SMP, for Survival MultiPlayer.  This version has gone through many different iterations, and at the time of this post, will be entering version 1.8 very soon.
There is also Minecraft Classic, often called Creative, with a limited sized world, and access to a wide amount of blocks, with the ability to create and destroy blocks instantly.  This version is free, and for a period of time, was the only version of the game out there.  As of Minecraft Beta 1.8, it will be possible to create a world with the infinite block placement/destruction, while having access to the many other features added to the game since the original version.