Is it OK to move a light aircraft by pushing or pulling the propeller?

Question: It's very common to see pilots moving a light aircraft by pushing or pulling on the prop, either because there's no tow bar available or simply out of preference or convenience. Is this a reasonable thing to do or can it damage the prop or engine in some way?
Comment: My first suggestion would be to read your POH to see what it says!  The answer may vary by aircraft model as well (especially geared -vs- non-geared engines).
Comment: does someone want to do the math on how much force needs to be applied to move, say, a 3368 pound airplane (my MTOW) forwards or backwards?
Answer: A couple of my CFIs have asked me to help them park the airplane (in absence of a tow bar) when I was pushing the airplane by putting one hand on the hub and the other on the propeller near the hub, and them (the CFIs) pushing the tail down and nose wheel elevated. But according to AOPA, it is not a good thing:

... never push or pull on the prop blades. Forget what anyone has told
you about pulling near the hub or the strength of the propeller.
Aluminum blades can bend, and it doesn't take much to put the blades
out of track with one another.

This PDF says the same thing:

Avoid pulling the airplane around by the prop. Yes, this seems the
perfect solution to a vexing problem of how to change the airplane's
position without having to walk around and get the tow bar, but it's
worthwhile to make the extra effort. Neither the engine nor the prop
particularly benefit from the loads imposed by horsing the whole
airplane around.

The FAA says in AC 20-37E

Do not push or pull on propeller blades when moving the aircraft by hand. Tow bars are specifically designed for this operation.
Comment: Isn't "horsing the whole airplane around" what the propeller _does_ during powered taxiing? The blades may not like asymmetric loads from handling, but transferring the force from pulling on the axle is exactly what the _engine and bearings_ are made to do, isn't it?
Comment: @HenningMakholm They are made to pull the plane straight forward, but not to push it backward or to one side or the other.
Comment: @HenningMakholm during powered movement it's the air pushing on the propeller blades, there's a maximum force that can exert, and it's fairly even on the whole propeller. I'll bet that pushing on a blade (especially on a tip) is more than the air could do.
Comment: Are the days of moving a prop and having the engine kick over loooong gone?
Comment: At my old flight school (Hillsboro Aviation) they also taught me this.  However, at Riddle the ramp is large enough that all airplanes can taxi without being towed at all.  This is probably to minimize any potential problems towing - such as what you mentioned.
Answer: Classic example of one corner case leading to a blanket belief.
Grabbing a propeller by the tip, especially a wooden prop, can cause damage. In use, the tips generate most of the thrust but are also held straight by the rotational forces.
Pulling on a prop right beside the hub will cause no harm - that's where the propellor thrust goes anyway. If you grab the prop on both sides the airframe won't know that the engine isn't running.
So, here's a Rule of Thumb: if you cannot touch the prop hub with your thumb while pulling on the prop, you are holding it too far out.
Comment: A literal rule of thumb.
Comment: I would add that I usually only do this when I'm moving the plane straight forward or back. If I have to turn it, I get out the tow bar (although I admit to kicking the tire left or right to make small adjustments).
Answer: Well, grabbing the propeller at the blade root and pulling from there cannot hurt it. Why? Because the thrust imparted by the propeller to the aircraft is applied at exactly the same place. In other words, the propeller pulls the airplane through the air at the hub. You are so close to the hub that you're not going to create a significant bending moment along the blade.
On the other hand grabbing the propeller at the tips would be questionable at best, and ill-advised!
Answer: I asked around at my gliding club about this, the consensus seems to be that it won't harm the plane as long as I didn't use excessive force.
The reason for doing it is to not have to walk from wing to wing to move the plane.  The main counterpoint is that you shouldn't move a plane by yourself unless you're very sure you won't hit anything (another plane, the hangar walls, etc).
Comment: I can't help but see irony in asking a _gliding_ club about this.
Comment: The main counterpoint for most propeller-driven singles I'm familiar with is "There's a towbar, it's *designed* to move the airplane, and you should use it!" :-)
Comment: That's true, but at my club all the planes are either taildraggers or private planes with wooden props.
Personally, I always get another person (or two) and push/pull by the wing struts.
Comment: Yeah, taildraggers are a slightly different beast, and I imagine wooden props are less prone to being pulled out of track than metal ones (?). They do make [taildragger tow rigs](http://i.stack.imgur.com/Rpn8w.jpg), they look like a lot more effort but I'd try to use one in preference to manhandling the prop :)
Comment: We have our own hangar that's big enough for the tow planes, the club-owned fiberglass ships, and some members' private airplanes.
Answer: As always with these questions it seems to be a religious thing. If you ask 2 people you will have at least 3 different answers and most of them will sound somewhat reasonable.
I had the situation that my FIs always taught and asked me to move the planes (taildraggers) with me pulling the plane on the prop and them steering using the rudder. A few days ago another guy walked up to me when I moved the plane shouting at me "NEVER do this, you'll destroy the prop"
So I called the technical support of the specific airplane (Diamond Aircraft) and asked them.
TL;DR: Manufacturer says that's exactly the way they move the planes in production when they don't have the tow bar around.
For reference: The plane has an electric constant speed prop so I guess about the most fragile you can find in terms of prop.
Of course you should always grab as close to the spinner as possible
One can verify plane specifically this from POH or AMM, for example Diamond DA 62 AMM states:

I know this thread is 4 years old but I could not find the questions answered anywhere else and the question comes up on a regular basis esp. in clubs where "knowledge" is passed on from member to member.
Comment: Thank you for the reference. I also looked it up in the DA20 manual and it even states you should rotate the plane towing on the prop: "If no  tow-bar is  used, during forward traversing the nose-wheel will  follow the  movement of the airplane. Change in  direction is achieved by  pulling on the propeller hub" (http://support.diamond-air.at/fileadmin/uploads/files/after_sales_support/DV20_Katana/Airplane_Flight_Manual/Basic_Manual/40102-r3-DV20-AFM.pdf, Section 8.4.1)
Answer: By deviating from the standard procedure (using the tow bar) you incur into the following risks:

Mechanical damage: you risk damaging propeller itself if you don't pull from as close as possible to the hub. Furthermore, being more complex, variable pitch blades obviously imply more risk.
Arguably, the forces in play during taxiing are similar to those exerted manually through pulling. Also, in my flight school, during pre-flight inspection we actually perform some push/pulls to assess that the propeller, hub, and drive are ok -- suggesting that there is no mechanical stress derived from doing so.
Safety risks: although arguably rare, you may accidentally start the engine through hand-swinging. I was instructed in my flight school to shut down the engine through the mixture control mainly to prevent this from happening during the pre-flight inspection previously described. This is also why we perform magneto ground checks during shutdown.
Comment: Maybe on an 80HP J-3, but you ain't hand propping my 270 HP high-compression TIO-540cu engine
Answer: How do you taxi your plane? I use my engine to spin my propeller, which pulls on the hub and pulls my plane hard enough to make it roll on the ground. On takeoff, I do this so hard that the 2000+ lb plane rolls 60 knots or so before it leaves the ground.
Now, with that in mind, do you think pulling on the prop, close to the hub, enough to move the plane 10 feet is doing any damage?
Answer: Regarding "it must be ok to pull the plane by the prop because the prop pulls the plane through the air"...
Yes....through the air. The air is much less sticky than the ground.
Also, the propeller doesn't pull the plane through the air, it pushes air behind the plane creating a lower pressure area in front of the plane and a high pressure area behind it. This "pulls" the plane into the low pressure area.
Comment: "Yes....through the air. The air is much less sticky than the ground." It also pulls the plane while moving on the ground (ie. taxiing). Also, the depiction of the pulling force as a result of a pressure difference is not very accurate.
Comment: The cause of the pulling force is not significant - the fact is there is a pulling force applied to the blades which is then transferred to the hub and crankshaft, which is transferred to the engine mounts, then the airframe, etc. What is different is the lack of rigidity in the blades when they're not rotating at high RPM. That lack of rigidity means you could bend them (or their attach points) much more easily by pushing on them. Which is why it's important to apply any force as close to the hub as possible - but not on the spinner itself!


How do I sync a Datel 270 wheel with an Xbox 360?

Question: I have lost the manual and cannot work out how to sync my Datel 270 wheel with my Xbox 360. Any ideas?
Answer: Apparently there was an issue with an update which caused issues with Datel 270 racing wheels when trying to connect them to the Xbox 360 console.
If this problem is still outstanding you could try contacting Datal Customer Support. There doesn't appear to be a manual online on their website for the Datal 270 wheel but they do answer queries reported via email.


When is a hand considered over

Question: When 2  players are all in and hand is completed dealt. Players turn over the cards and one player has 3 of a kind and the other players has A high. The five turned up cards on table are picked up with the 3 down cards when someone at the table states that the person with the Ace high really had a flush. Can you go back and check the cards to see if there was a flush
Answer: Under the rules, a player who properly shows his hand is entitled to the pot if the hand wins, regardless of his actions or those of others. This is the "cards speak" rule. Also, the dealer and other players at the table are entitled--and indeed expected--to assist the dealer in assuring that the pot is awarded correctly.
Whether or not a player can be awarded the pot comes down to what the dealer/floorman/casino are capable of and willing to do. If the hand can be reasonably reconstructed from cards in the dealer's hand (mucked or otherwise) and player testimony, then certainly a floorman should do that. If the cards are not retrievable but the floorman can easily check a camera, then he can do that as well. I have awarded many pots by camera when the players had a dispute about the winner after the cards were mucked--but I stress the pot can only be awarded if the camera shows that the player properly tabled his hand at showdown.
If the pot was pushed and mingled into a player's stack and the dealer has begun shuffling for the next hand, a floorman might well rule that it's too late to object to the result, especially if the room is busy/understaffed and he simply isn't able to go to camera.
In any case, players should be reminded to look after their own interests and hold onto their cards until they are quite satisfied with the result, and not just rely on the dealer.
Answer: If the board has already been mixed with the burn cards (which I presume are the "3 down cards" you refer to), it seems unlikely that a floor would rule to turn all 8 cards back up and try to determine which 5 were the board. If it is not possible to determine 100% which 5 cards were the board without also revealing the burn cards, I would suggest the mistake cannot be reversed and the player with 3OAK wins the pot.
It's the responsibility of the player who had the flush to speak up if an error is made in reading their hand - they should have said something before the pot was awarded to the player with 3OAK, or the board was mucked.
Answer: At the casino I work at, (large place with fountains on the Las Vegas strip, that I do not speak for), the official time that a hand is over is when the shuffle starts for the next hand, the shuffle starts at the first riffle or push of the button on a shuffle machine.
In the particular case you describe, the next hand is technically not started so the floor would make a decision on it. If the players involved are generally agreed that the person had the flush, fine the pot is awarded thus. If there is disagreement the floor and dealer might dig through the muck to attempt to recreate the hand, then decide, the floor person might just make a decision based on player testimony etc. If they really cannot come to a decision everyone is content with at the table they would do a video review if possible. Sometimes video review is not possible, not all tables are always covered adequately. In this case without cooperation from the players and some evidence the floor person is comfortable with, the pot will stay as awarded.
However, there can be exceptions to this timing on the hand ending depending on the nature of the problem. When an exception can be made is subjective to many factors. Like lee said in his post, if he is not to swamped he can review video, and typically the less serious the consequence is to the players the less swamped he has to be to go to the video. The time since the hand actually ended also degrades the likelihood that the floor person will make a decision on a situation. If the player three hands later suddenly gets an inkling that he might have had a flush, he is more likely then not out of luck.
Ideally we always want the pot awarded to the winning hand at showdown. However, having to call a floor because someone may have made a mistake is disruptive to a game and the process itself is not always accurate to determining the best hand. The ideal behind a simple rule that says that time is up when the hand is done is meant to minimize this kind of disruption. A floor person can always make exceptions depending on the merits of the situation or not.
Answer: Here is the order
Let just assume 2 players for ease

Betting complete
Last aggressor shows
Caller either mucks or shows
Dealer awards the pot
Sometimes need to count out some chips if two all in
Dealer moves chips to winner
Dealer mucks the board

The point of no return is pretty much when the chips are moved. If the player did not recognize and defend their hand by then that is their problem. The chance of a dealer not reading a hand correctly pretty slim.
The board has been out the whole betting round and player does not know their hand? It happens - Phil Ivy mucked an ace high flush with 4 flush on the board.
Comment: Pots can and have been returned to a player days after the hand took place, because X-ray was paying attention but the winning player left before they had told the supervisor. Calling the award a point of no return is misleading. And mucking a hand without revealing it first is irrelevant to this case, since all hands have been shown in the OP due to the all-in. Cards speak, the flush wins.

When is a hand considered over


Specifying a position and velocity of body in a Kepler simulation

Question: I've built a model of the Solar System by calculating Keplerian orbital elements. The model takes a time $t$ which is incremented with each frame of the simulation. I then calculate the new positions of each body. $t$ is really the time since perihelion for each orbit.
This means that at the beginning of the simulation each object starts at its perihelion (since $t=0$). So, now I'd like to place a new body (a comet, for example) with a position $P$ and velocity $V$. From $P$ and $V$, I calculate the orbital elements such as eccentricity $e$, semi-major axis $M$, etc.
Now, I can calculate the next position of this new body (since $t$ has been incremented) using these orbital elements. However, since $t$ is the time since this new orbits perihelion, the calculated position will not be the next incremental position. One solution to this could be that I calculate the time ($t\text'$) at which this new orbit would position the body at $P$ and increment $t\text'$. This means that instead of having a global $t$, I have a $t$ for each body which is incremented at the same rate.
Does this sound sensible?
Answer: You can do both.  For each object, store the time of perihelion.  You have a global time for observation.  A subtraction gets the time since perihelion.


Easiest way to scan books?

Question: What's the easiest tool to use to scan books? I find that using my scanner is difficult for books?
Answer: If you can separate the pages from the book (i.e.: break the book) I will suggest you a Fujitsu Scansnap S300 because It's a good product (stellar reviews) and can OCR your book making It a searchable PDF.
If you're brave enough you can build a system yourself
If you think there could be an e-book (you've not said which book you want to scan) copy of your textbook try to purchase It.
There are incredible projects deidcated on this subject and It's worth mentioning a company: Atiz
This kind of device, depending on the number of pages you want to scan, can come in handy.
Answer: There are local agencies in large cities which have this service, daily.  I'm not sure if China, India, etc offer a similar service at competitive prices.
e
Generally, I don't scan.  Newspapers, periodicals, books ...
I use my smartphone and /or my compact digital camera.  Then read it on my smartphone, notebook or netbook.  If I really want hardcopy, I laser-print any pages.
For uploading into assignments, Omnipage (optical character recognition) in Window$$$$.  Linux has a few free OCR programs, which i've installed, but have not tested.
Greg Zeng, Retired (medical) IT Consultant, Australian Capital Territory.
Answer: You can use xcanex.
Tt can scan 16pages in 5 mins.
Use at home.
It also can be used to scan card, documents.
Answer: A scanner with a document feeder should do what you're looking for - try to keep it to 5-10 pages at a time and hope that the pages aren't wrinkly at the edge that goes into the feeder.
Answer: There are also scanners such as this one that allow you to scan almost to the center so you can do it on an intact book without breaking the spine.  I haven't used it, though.

Easiest way to scan books?


How do I increase my wrist strength for punching?

Question: When I throw a punch, sometimes my wrist doesn't stay straight and I run the risk of spraining it. What kind of exercises can I do to strengthen my wrists so that my wrist isn't going to bend when I punch?
Comment: Also check out the answers to [building up grip strength](http://martialarts.stackexchange.com/questions/294/what-are-good-exercises-for-building-grip-strength-for-judo-and-bjj).
Comment: Pikup a copy of John Brookfield's book "Mastery of Hand Strength". Lots of good information.
Comment: You can strengthen your wrists with hand gyroscope — 'powerball'. This helps me a lot doing badminton and knife fighting.
Answer: I feel there's a core issue here being neglected:

When I throw a punch, SOMETIMES MY WRIST DOESN'T STAY STRAIGHT and I run the risk of spraining it.

If I could highlight, underline, and make it flash, I would. Your issue here is not simply wrist strength (which, by the way, is not going to be corrected by simple strength training alone), but rather your form. Let me do my bold and caps thing again here to drive this point home:
IF YOUR WRIST IS OUT OF ALIGNMENT, YOU RUN THE RISK OF SPRAINING YOUR WRIST
Shocking, I know, but there's a key here: If your wrist is out of alignment. If it's not, your strike will be true, the impact will be absorbed down the long bones of the arm.
I really can't stress this enough: you must work on your form before you can rely on your punch. So, let's break down a punch (not necessarily your punch; I don't have any idea what you're studying, so I'll describe one method:

Hold your arm straight out in front of your chest, fingers pointing ahead at a stationary target.
Curl your fingers from the furthest joint inward into your palm. Keep your thumb pointing straight up like you're giving your target a thumbs up.
Curl the thumb from the joint downward to rest on the first knuckle of the index finger. If you're looking straight down your hand, your thumb should be acting like an iron sight on a firearm.
Align your wrist. The position of your thumb should make a small tendon at the side of your wrist bulge slightly. Use this as a line through your thumb into your target.
Pull your elbow back keeping your wrist in that alignment, and practice pushing forward with that fist, like you're slowly punching. Practice keeping your wrist in alignment.
Step up to the target and slowly punch. Right now you're practicing just maintaining that alignment. Pick up a little momentum without putting your body into the punch yet.
Now, relax every muscle, just taking on a very relaxed posture. Curl your fist as before and make a slow loping punch at your target. Punch however feels natural, but maintain that tension in your wrist only. Maintaining that alignment is critical to throwing a decent punch.
Practice, practice, practice. Build up speed slowly, and start adding more body rotation into the strike. Be patient; this won't happen over night, but this is the truest way to build the right sort of strength for striking.

Punching with good form is its own workout. Your body naturally adapts to the lifestyle you set it to: If you work in a job sitting at a desk for 8 hours a day, your body adapts to that; if you chop wood every day for 2 hours, your body adapts to that. Punch to build the strength you need in the right muscles rather than performing exercises that target general groupings at the risk of not developing essential muscles.
Comment: -1 Form is always going to break down once he hits anything but air; strength is necessary to maintain good form in anything but kata-based arts.
Comment: I'll vouch for this. My girlfriend, who does Krav, told me her wrist hurts whenever she tosses a hook punch. First punch I could see her from for the punch was off. Couple of quick tips and no more pain when tossing a hook.
Comment: @DaveLiepmann Punching a bag with proper form is creating resistive tension in the muscles of the forearm that brace the wrist. The strength of your wrist is not static; it adapts to the stresses under which it's placed. Two quotes for you: *Practice doesn't make perfect; perfect practice makes perfect.* And *If you want to be better at **X**, do **X***
Comment: @stslavik While I still disagree with your assertion that doing X is always the best training for doing X (see Practical Programming for a thorough refutation), and I think that strength is still an area of concern, I see your point that you are advocating hitting a target. I can't undo my downvote without an edit. Maybe emphasizing the "hit an object with force" (as opposed to "punch the air or punch a target gently") part of your answer would be a good edit that would allow me to undownvote.
Comment: @DaveLiepmann Your comment is invalid: Striking against something is implicit in both the question and answer.
Comment: Making it more explicit would help, because your solution (proper fist-making) has very little to do with impact. But implicit or not, focusing on form alone is not sufficient advice for those who are **too weak** to maintain proper alignment when hitting something.
Comment: But thanks for taking my feedback into consideration!
Comment: @WayneInML Different issue, different solution. I don't think bad form should be left bad. I think that it's totally different from buckling during good form due to weakness.
Comment: Without seeing a video how do we know it is bad form or bad wrist strength? My experience tends to say form is usually the fault the majority of the time. YMMV. I would disagree that form always breaks down once you hit anything but air. Again, just my experience.
Comment: Suggest link for "Practical Programming" (There are about 2 dozen similar titles in various media). I made my point; you feel the information is wrong or dangerous, and we've both made our relative arguments. I'll leave it to the community to decide their view.
Comment: @stslavik Didn't see the request for PP link till just now -- it's this one: https://encrypted.google.com/url?sa=t&rct=j&q=practical%20programming&source=web&cd=1&cad=rja&ved=0CCEQFjAA&url=http%3A%2F%2Fwww.amazon.com%2FPractical-Programming-Strength-Training-Rippetoe%2Fdp%2F0976805413&ei=u-E6UOrOM4bn0QHUuIFQ&usg=AFQjCNFpmTn_dkBcN6Wq02uk63HpZdnASg&sig2=a5OZ0WRw5InKpzRtWC5EBQ aka http://www.aasgaardco.com/store/store.php?crn=199&rn=328&action=show_detail
Comment: @DaveLiepmann - I tend to agree with _stslavik_ in the assertion that the main trouble is bad (or lacking) form of the hand when delivering a punch. Focusing only on increasing wrist strength without fixing the root issue of wrist alignment in the punch will perhaps mask the issue in the short run, but in the long run it will most likely be opening the way for even worse injury down the road.
Answer: There are a few things you can do:

Knuckle pushups
Fingertip pushups
Kettlebell presses
Heavy bag work

The knuckle pushups have the following benefits: strengthens the fist, strengthens the forearm muscles.  But they also have some drawbacks: rough on your knuckles, overdoing it can induce joint pain.
Fingertip pushups also strengthen the forearm muscles, and help with knife-hand techniques.  They are hard to do, but well worth your time.
Kettlebell presses are my new favorite.  The uneven loading of the kettlebell strengthens your grip, and the movement of the kettlebell press also strengthens your rotator cuff muscles (the smaller muscles in your shoulders).
If you don't have access to a kettlebell, you may want to try alternating pushup styles:

a set of 10 fingertip pushups
a set of 10 knuckle pushups
a set of 10 standard pushups

If you have access to a heavy bag, that will give you the most direct work to get used to punching.  However, I recommend on not taping up or putting gloves on.  As a martial artist you need to toughen your hands to be able to hit properly.  Sure, the rough material on the bag doesn't feel good--but it's a part of toughening the skin as well as the joints involved in the punch.  Concentrate on technique and form.  Use your hips.  Don't try to be fancy.  If you need to buy a heavy bag, I recommend a good 50lb bag.  Any heavier than that is unnecessary, and potentially will wear out your joints quicker.
Comment: That's why you focus on technique.  Power can come later.
Comment: Note: not taping up (and not putting gloves on) may result in severe damage to hands if striking improperly.
Answer: Strength and Form, Not Wrist-Specific Strength
Your best bet is improving your overall strength, not your wrist strength specifically. This, along with practicing good form with your punch against resistance, will keep you from bending your wrist. As Mark Rippetoe points out, it is more productive to get you strong, rather than get your wrist strong:

Strength is the most general adaptation. It is acquired most effectively through exercises that produce the most force against external resistance, and as such is always best trained with five or six basic exercises. The same exercises that are correct for weak football players and lifters are correct for weak volleyball and baseball players, because the best way to get strong will always be the same. Strength is NOT specific, and cannot effectively be acquired through exercises that mimic sports-specific movements, because these movements lack the potential to produce as much force as general barbell exercises, and therefore lack the capacity to make weak athletes as strong as barbell training.

Focusing on wrist strength alone will lead you to do physical therapy or bodybuilding-style isolation workouts. You'll get just as much wrist strength by doing whole-body strengthening exercises, with the added benefit of being stronger all over. Wrist rollers, wrist curls, and other hyper-specific work is best left to the injured, or those who are strong but have a specific deficiency.
That doesn't mean you can't get yourself stronger alongside some punching-specific work. How?
How
Hit things. Bag work, as suggested by many others, is a great suggestion. Keep it light and short as you start, and gradually ramp up the intensity over several weeks. Focus on maintaining good form with a straight wrist. Historical implements like the Okinawan makiwara or the Chinese wall-sandbag are useful too, though they omit the (enormously helpful) element of simultaneously training your footwork. Hitting something reinforces proper mechanics while at the same time making denser bones and stronger soft tissues.
Lift. If you want stronger wrists, I imagine that push-ups, pull-ups, and presses should be central in your lifting program. Normal push-ups are okay at first, but clapping or knuckle push-ups are superior and should be switched to as soon as possible. Pull-ups, particularly on a thick bar, rope, or towel will strengthen your forearms (as well as most of the rest of you) and thereby help you maintain wrist position as you punch. Adding weight will be another great help, so overhead presses, performed with lots of weight for low reps, will train your ability to keep the wrist straight under heavy loads. Those will work with kettlebells, dumbbells, or barbells (in decreasing order of my opinion of each tool's wrist-strength specificity).
Answer: Vertical Knuckle push ups on a soft surface will train your alignment and improve the stabilising muscles around the wrist.
Keep the elbows close to the body and use the front 2 knuckles of the fist.
Do not allow your wrist to buckle side to side - keep the correct alignment through your hand, wrist and elbow.
This gentleman's left arm has good alignment, but his right wrist has buckled.

If you need an easier introductory form, try simply holding the push up position with the arms fully extended and try completing the same push ups from your knees.
Answer: bag work ( punching bag ).   Just glove up and start punching,  going light,  building up.  Practice coming in from different angles.
You don't have to do LOTs of this, just a regular 10 - 15 minute session working the bags will do a lot for improving the your whole of your punch, including wrists bending on impact.
Answer: I had the same problem.
I did the following to strengthen my wrist.
I still do end up bending my wrist occasionally but mostly the problem has gone.
1) Take a tennis ball (or any other not too hard one) and squeeze it. This will help develop the grip strength and help hold the wrist in alignment when punching.
You could also do it with one of those grip strengthening devices.
2) Jump Rope!
   Jumping rope with a heavy rope. (Focus on maintaining the rhythm instead of speed). The rope has to be heavy enough to cause fatigue in the forearm. This helped my develop forearm strength and hence keep the wrist in alignment.
(Do not keep too tight a grip on the handle and let your wrists roll a little.)
Answer: simple dumbell exercises are great for strengthening wrists.   i did a lot of these when i was having trouble with wrist pain and it helped a lot.
there are 3 movements you will want to do.
palm down  curling your wrist up and down.
palm up curling your wrist up and down.
palm down or up, tipping your wrist side to side.
start with a fairly light weight so your wrists can get used to the movements, and increase the weights as you go.
i see a lot of people posting about doing pushups to strengthen wrists, and while push ups are great for general strength and whatnot, if you have weak or injured wrists, there are exercises you should be doing before attempting knuckle or finger tip pushups.
Answer: Just want to throw some Hojo-Undo in the mix.
Specifically the Chi-Ishi and Ishi Sashi.
After a few weeks of using the Chi-Ishi my wrists and grip strength were noticeably improving, and the tools are really simple to make.
Answer: One simple one I used to do until I got decent strength in my wrists was wrist raises and twists with a light dumb-bell or barbell.
In a seated position, rest your elbow on your knee, forearm out in front with a light dumb-bell.
Raises palm down or palm up help to strengthen the main muscles in your forearm which hold your hand rigid, and twists help to strngthen the twisting muslces.
Answer: There are some really good answers but I'd like to add some more into the mix.
You can do:

Fingertip push-ups
Knuckle push-ups
Dolphin push-ups
Push-ups with a broomstick in each hand (thumbs up)
Use rice buckets and grab and roll your hands in it (great exercise, by the way)
Grip training (don't forget pinch and extensions)

Additional tip: don't use any wraps or thick gloves during your heavy bag exercises as it is totally contrary to what you want; hand wraps and thick gloves stabilize your hand and wrist, which won't help you get stronger wrists. Use light thin heavy-bag gloves!
Answer: What really helped me was to tie one end of a rope around a section of dowel rod, the other end to a 30lb weight, lift the contraption off the floor (with feet wide apart in case of system failure), and turn the dowel rod to slowly "wind" the rope around the rod, first up, then slowly down... then repeat the other way.  Keep your back straight to avoid strain.
Answer: Of all the answers I like Patricia's best.  There is little musculature in the wrist proper.  The muscles that flex the wrist or hold it stable are in the forearm.
Hand-curling motions, hand extension motions....The old classic "wrist roller"....All these strengthen the flexor and extensor musculature in
Answer: You could try punching walls a bit. Slowly punch the value and punch in such a way that you feel only your knuckles against the wall. Slowly increase the power behind your punch. It helps a lot. I have been doing that for some time now.
Have fun :)


Android: 2d scrolling background

Question: I am a very beginner in game development. All I want to achieve in the beginning is a free scrollable background like in a strategy game with my custom graphics. In my case it is supposed to be a 2d city map where the user can select buildings.
How can I achieve that as easy as possible in android? With OpenGL? Die you have any examples especially for this scrolling functionality?
Comment: You can achieve this effect by adding any background velocity when the character is stopped. Let's set this speed to 5. Assuming your character has a speed of 10. When it goes forward (right) the background speed will be 15 and when it goes backwards (left), the speed will be -5. That's if I understood your question.
Answer: I think you should go with frameworks like Libgdx rather than using directly OpenGL. Libgdx allow you to draw graphical assets and program interactivity with them.
Here is some starting points :

Libgdx wiki on Github
Libgdx official documentation
Comment: I don't think this answers the question, OP is using OpenGL and a scrolling effect is easy to do.
Answer: If you want the buildings in the backgroudn to be clickable you could create different classes for each building, assign an image to the object and use ArrayLists to determine how many you would like in the background.
You would have to run a thread in your main class to move the buildings either right or left, check the locations and if x - image.getWidth < 0 then the whole building has left the screen, this means another building needs to be added to the right.
Answer: I had a similar problem when I wanted to create a scrolling background. I found the following tutorial (in Java) which is quite easy and worked:
http://gamecodeschool.com/android/coding-a-parallax-scrolling-background-for-android/

Android: 2d scrolling background


How did Harry come to master the Elder Wand?

Question: Harry takes Draco Malfoy's hawthorn wand, not the Elder Wand. How, then, does he become the master of the Elder Wand, which he never took from its true owner (Draco), or touched? Does a wizard lose the allegiance of all his wands if even one of them is taken from him? Pretty risky innit?
Answer: This is a complicated topic.
What is not made clear in canon, but is explained later by J.K. Rowling, is the fact that

if a wizard or witch defeats another and earns the allegiance of their opponent's wand, all wands under the control of the opponent switch allegiance to the victor and it is possible for a witch or wizard to be the master of more than one wand at a time, and to lose the allegiance of more than one wand at a time. [Emphasis mine]

Draco Malfoy was master of both his hawthorn wand (the wand that chose him at Ollivanders when he was eleven) and the Elder Wand, following his disarming of Dumbledore on the Astronomy Tower the night Dumbledore was killed.
When Harry Potter defeated Draco Malfoy by taking Draco's wand at Malfoy Manor, not only did Draco's hawthorn wand switch allegiance to Harry, but the Elder Wand did as well. As noted, Draco never knew he was master of the Elder Wand at any point. Furthermore, the Elder Wand chose Harry as its master.
In Deathly Hallows, Voldemort says,

"But then, Potter, Dumbledore as good as gave me the wand!" Voldemort's voice shook with malicious pleasure. "I stole the wand from its last master's tomb! I removed it against its last master's wishes! Its power is mine!

To which Harry replies:

"You still don't get it, Riddle, do you? Possessing the wand isn't enough! Holding it, using it, doesn't make it really yours. Didn't you listen to Ollivander? The wand chooses the wizard . . ."
(Deathly Hallows  --  Chapter 36)

J.K. Rowling has shared that the core of the Elder Wand is the tail hair of a Thestral, "a powerful and tricky substance that can be mastered only by a witch or wizard capable of facing death. J.K. Rowling Therefore, Voldemort would never have been able to truly master the Elder Wand, no matter how he came to possess it. Voldemort was incapable of facing death. As we know, Harry faced death twice, once unknowingly as an infant, once deliberately as a teen. Accordingly, Harry was able to both master and win the allegiance of the Elder Wand.
Comment: @Slytherincess Regarding »if a wizard or witch defeats another and earns the allegiance of their opponent's wand« — Do you know if JKR has ever said anything about what exactly causes a defeat to result in a change of wand allegiance? It's obviously not every defeat that does so, or wands would be changing allegiances left, right, and centre every time someone successfully _expelliarmus_'ed someone else in one of the many fight scenes in the series… so why does Harry 'win' the hawthorn wand when disarming Draco at Malfoy Manor, but not when _sectumsempra_'ing him in Myrtle's lavatory?
Comment: @user21820 You're right, of course; that was in _Half-Blood Prince_.
Comment: If the plot was relying on your last paragraph, that's just about the most glaring omission in the entire series, maybe even all of literature.
Comment: So Dumbledore and Malfoy must have faced death to become masters of the Elder wand and to pass the mastery to Harry?
Comment: @Zikato Not necessarily. But unlike Voldemort who feared death above all else and was _incapable_ of facing it, there's nothing to suggest that Malfoy or especially Dumbledore (who we know did face death quite calmly) was particularly incapable of facing death, should the need arise. That's not to say he necessarily _had_ done so; but he _could_, unlike Voldemort who, up until the very last second of his life, refused to consider his own mortality and regard death as a possible event to occur to him.
Comment: Where is the first quote from? Is it possible to add a link to it?
Comment: @JanusBahsJacquet: If I recall that was quite some time before Draco disarmed Dumbledore.
Answer: Since Draco took the Elder Wand from Dumbledore's hand (and thus, 'defeated' him, via disarming), the allegiance of the Elder Wand passed to him (even though Draco didn't use it).
Later when Harry took the hawthorn wand from Draco, the Elder Wand knew that Draco had been "beaten" and it changed its allegiance to Harry Potter. It was simply waiting for him to gain possession of it.
Comment: Look at it this way; it was taken from the hand of it's owner by the holder of the hawthorn wand (Draco).  That wand was taken from it's owner by Harry.  Even though it was not taken directly by Harry, the chain of dominance remains unbroken -- Harry defeated Malfoy who defeated Dumbledore.  The wand simply recognizes when it's owner is defeated and gives it's allegiance to the victor; the fact that it was never in his hand is irrelevant -- the wand 'knows'.... It seeks the 'best' to be held by, and it determines this by who wins.  Lose while you have it's allegiance, and it serves the winner.
Comment: But that doesn't make any sense. According to Ollivander, the WAND has to be won from its owner, in order for it to change allegiance. Harry didn't win the Elder Wand; he won the hawthorn wand. If this wasn't the rule, no one would want to win another's wand. If he lost it or gave it back, he'd lose his own too (lose one of your wands means losing all of them to the winner). Capturing another's wand increases your vulnerability to your wand switching allegiance. If you ask me it makes more sense that the Elder Wand refused to attack Harry because it thought Draco was holding the hawthorn wand.
Comment: @Jay (Moving out of Universe) There are many many inconsistencies in HP if you start looking too hard, a degree of suspension of disbelief is necessary.
Comment: It's magic -- what sense is it supposed to make?
Comment: I would take it that the Elder Wand is an exception.  It specifically allies with whoever has defeated the last master, under any circumstances.  Even in the story, one wizard beat the other by stabbing him with a knife.  That means the Elder Wand changed allegiances through a totally non-magic method, which is way stranger than it changing allegiances because someone was beaten magically using a different wand.
Comment: @Richard Sure there are inconsistencies, but this is the most crucial one, since it's the key plot point that allows Harry to defeat Voldemort. And TangoOversway, I don't think JKR would want to bring the series to an end with a lazy deus ex machina like "it's magic". I'm not completely satisfied with any of the answers but it at least proves that no one really has a clue and I don't feel alone anymore. :)
Comment: The Elder Wand is cursed. That is why it doesn't require its wielder to be beaten while it is used (as most wands do). It only requires that its wielder be beaten in some fashion.
Comment: Honestly, "the Elder Wand thinks Harry is Draco because he's holding Draco's wand and since Harry never took the Elder Wand off Draco, it's still Draco's" would have made more sense than this mess of an explanation (I'm criticizing the author's logic, not your answer).
Answer: The wand's allegiance changes when its master is "defeated."  Evidently, being disarmed counts, which I think makes sense.  If you've disarmed a wizard, they're at your mercy, you've essentially defeated them.  It doesn't matter whether the wand is present; since it is magical, it will know its master has been defeated, and by whom.
Yes, that is dangerous, but it's a dangerous wand.
Answer: In the book and the film "Harry Potter and the Half Blood Prince" it appears that Snape disarmed Dumbledore, from the way Harry was looking at it. In actual fact, Malfoy did disarm Dumbledore, but had no clue that he now possessed the wand. Lord Voldemort, in thinking Severus Snape had disarmed Dumbledore, destroys him with the Avada Kedarva curse. However since Snape did not actually disarm Dumbledore, the wand wouldn't cooperate with Lord Voldemort.
After looking at the Pensieve, Harry realizes that Snape was not to blame for Dumbledore's death and figures out that Draco Malfoy did disarm Dumbledore. After Harry Potter defeats Lord Voldemort, he actually explains to Hermione and Ron how he had just recently disarmed Malfoy, making Harry owner of the wand. However, seeing as the Elder Wand with its powers has caused so much trouble, wars and deaths alike, he places it back into Dumbledore's grave (in the book; in the film he snaps it in two), thinking the wizarding world would be much better without it.
Answer: By disarming Dumbledore using Expelliarmus, Draco became the true owner of the Elder Wand. At Malfoy Manor Harry disarms Draco, meaning, unbeknownst to him, that the Elder Wand is his. However, Voldemort believes that you have to kill a person to get it, making it so the wand goes from Dumbledore to Snape to Voldemort. Ollivander senses Draco's original wand's allegiance has changed because he temporarily had possession of the Elder Wand. I assume that his first wand may have felt betrayed and from there I'm not positive about Draco's first wand.............????
Answer: Here is an attempt at a reply to the initial question. I think, and I am not well acquainted with the books, that it is a special feature of the elder wand, a special feature of "power", if you will, that its allegiance is of such a transient nature. However, in my point of view that is not necessarily intrinsic to ordinary wands just as much.
Answer: I think this makes more sense though: Draco disarmed Dumbledore therefore NOT defeating him. Snape killed Dumbledore so the wand was then his. Voldemort killed Snape so the wand was then Voldemort's and Voldemort was killed by Harry but then Harry snapped the wand in two and threw it away. Does this make sense to anyone else but me?!
Comment: The only problem with your chain of logic is that your first step is directly contradicted by the books. It is explicitly stated that Draco's disarming of Dumbledore made Draco the master of the Elder Wand.
Comment: Wand can change allegiance when the previous owner is defeated, Olivander say that Draco Wand change the allegiance to Harry when he takes is wand in Malfoy manor. So when Draco disarms Dumbledore he change the allegiance of to Elder Wand to himself, and Harry have the allegiance of two wands, Draco´s and the Elder Wand.


Org agenda remove todo in bulk

Question: In org agenda mode, select several items, mark them with m, then set the todo status B t to none. Normally I can remove TODO status with t SPC but B t SPC isn't permitted.
Answer: After a glance at the code I think the 'fast-todo-selection' does not go together with agenda bulk marked items, yet.
Possibly you want to file a report on the org mode mailing list so the issue might be addressed.
As workaround I propose to customize variable org-agenda-bulk-custom-functions via M-x customize-variable.
You can use SPC as character and (lambda nil (org-agenda-todo "")) as function.
With this setting B SPC removes the todo states of the marked items AFAICS.
Comment: This seems to work, thanks. `(setq org-agenda-bulk-custom-functions '((?\s (lambda nil (org-agenda-todo "")))))`
Comment: N.B. The `?\s` part specifies the character. e.g. `?C` would make `C` the character to be pressed instead.

Org agenda remove todo in bulk


Replacing steel strings with nylon strings

Question: I bought a guitar which has a classical guitar bridge but a steel guitar tuning pegs and strung with steel strings. I'm wondering if I could replace the steel strings with nylon strings.
Comment: Hi, sounds unusual, could you post a photo, please (either make one or find one on the internet)? As well, remember that nylon strings are less forceful on the neck than steels so you can replace them. I'm not sure, however, of the quality of the resulting sound.
Comment: Good luck getting and keeping that thing in tune,.
Comment: @NeilMeyer: My favorite instrument is a steel-string acoustic electric strung with nylon strings.  Once a set of strings is broken in, I've found pitch stability to be better than my steel string guitars.
Answer: Usually it's the other way! No reason why this can't be achieved, but the tension on the strings will be less, affecting, possibly, the relief on the neck. In other words, the neck may well straighten out, and this can cause the strings to be too close to the fingerboard, thus rattling. If the neck has a truss rod and the bridge is adjustable, all will be well.You may or may not like the resulting sound, though, as it will be quite different.
Comment: thrue - some steel strung guitars are built for quite thick strings so when you put more floppy nylon ones on, they don't resonate as well. You certainly won't harm the guitar so worth a try. Putting steel strings on a classical guitar is more likely to cause issues in bending the wood.
Answer: Guitars designed specifically for nylon strings typically do not have a truss rod to compensate for string tension.  If your guitar is designed for steel strings, it should have an adjustable truss rod visible either through the sound hold in the neck block or under a plate where the headstock joins the neck.  The truss rod can be adjusted to allow the proper relief to keep the strings from being too close to the frets which would cause them to buzz or not play at all. Without a truss rod, the tension of the steel strings would cause the neck to bow and the strings to be too high off the fret board in the middle of the fret board.  Nylon strings do not create the same amount of tension on the neck, thus many guitars designed specifically for nylon strings, will not have a truss rod.  Going from steel strings to nylon strings will create less tension on the neck and so would not hurt the guitar.  But nylon strings will not sound the same as steel strings.  Also, nylon strings tend to be larger diameter and if the string slots in the nut (at base of headstock) are cut for steel strings, the nylon strings may not seat properly in the slots.  A qualified luthier or guitar tech can use a nut file to enlarge the slots should you desire to permanently convert to nylon strings. Or you can replace the nut.


Maximize and Minimize Buttons disabled on my Quickly application

Question: I was editing some basic settings in my application window design in Quickly/ GTK when I noticed that when I ran my app there was only a close button, not a maximize or minimize button. I know this is probably a silly question, but I cannot find the setting to enable them any where. Please help! :)
Answer: Only way I found to re-produce your problem, was to change the Type hint in the general tab - in the window properties . Try changing that back to Normal, if not already done.


Convergence/Analyticity of a complex function

Question: Where is the function $(\cos (z))^{1\over 2}$ analytic? In other words, where in the complex plane $\mathbb C$ is the above function's series representation convergent?
Comment: It depends on what you mean by $(\phantom z)^{1/2}$.
Comment: @DylanMoreland: What do you mean?  Suppose I take the principal branch?
Answer: You ask two questions which are not equivalent. Well, it depends what you mean by the function's series representation: If you take the Maclaurin series for the function based on the principal branch of the square root, the series will converge in the circle of radius $\pi/2$ and center at the origin.
However, if you take the complex plane and remove two slits along the real line, namely $(-\infty,-\pi/2)$ and $(\pi/2,\infty)$, what is left is simply connected, and $\cos z$ has no zero there, and so your function will have a unique square root with value $1$ at $z=0$. It will have another square root being the negative of the first, of course, and together the two will define a the Riemann surface of the function.
Think of it this way: You take two copies of the plane, slitted as indicated above, and call them sheets. Now, at every interval $((4k+1)\pi/2,(4k+3)\pi/2)$ along the real axis, where $k$ is any integer, glue the two sheets crosswise, so the top sheet in the upper half plane is glued to the bottom sheet in the lower half plane, and vice versa. Meanwhile, in each interval $((4k-1)\pi/2,(4k+1)\pi/2)$, glue each sheet to itself (upper to lower halfplane). (For the case $k=0$ there is nothing to be done, as the sheets are already connected across the interval $(-\pi/2,\pi/2)$.)
Finally, your function $f$ can be defined to be the principal branch, as defined further up, on the top sheet and its negative on the bottom sheet. The glueing operation as defined above ensure the continuity of $f$ across the real line, except for the points $(2k+1)\pi/2$, which will be branch points of the function.
In hindsight, we see that we could have avoided half the gluing operation by starting with the sheets being copies of the complex plane with the intervals $((4k+1)\pi/2,(4k+3)\pi/2)$ removed. Then we just glue the two sheets crosswise across the remaining intervals.
Answer: If an entire function has no zeroes, then it has an entire square root.  Otherwise, you have to make branch cuts between the zeroes in such a way that every simple closed loop in the plane not passing across a branch cut encircles an even number of zeroes, counting multiplicity.  (If there are only finitely many zeroes, some branch cuts may need to go to infinity.)  Harald Hanche-Olsen's answer gives one way of doing this.
More generally, for $n$th roots, replace "an even number of zeroes" with "a number of zeros divisible by $n$".  For logarithms, replace with "no zeroes".


Add Timestamp to File Name in Flash Media Server

Question: Is there some way to dynamically name files published in Flash Media server.
Several clients in an application will be publishing to FMS.  They may start and stop recording several times, and I would like to append a time stamp (format: yy-mm-dd-hh-mm-ss) to the file name in main.asc.
For example the following files might be created by clients 1 and 2 using the ns.publish(myclientName); command;

client1's first recording client1_2011-01-01-22-47-01.flv
client1's second recording client1_2011-01-01-22-54-55.flv
client2's first recording client2_2011-01-01-22-59-34.flv
client1's third recording client1_2011-01-01-22-04-12.flv

I don't want to use ns.publish(myClientName, "append");.  There needs to be a separate file for each publish session.
The best I can come up with is to use File.creationTime and File.renameTo() on application.onUnpublish() to add the timestamp when publishing has ended, but it it wouldn't be tolerant of an unexpected server outage.
Edit:  Unknown to me and in conflict with the documentation, the Date object in Flash Media Server is not the one we know and love.  It has no properties.  For example
var currentTime = new Date();
trace("CurrentTime: " +currentTime.time);

prints

CurrentTime: undefined

Running
for (var prop in currentTime)
    trace(prop);

prints nothing.
I was surprised and frustrated after an hour or so to learn this.  Hope it helps someone.
Answer: currentTime.valueOf() is timespan


How to change the time for OS selection menu in GRUB?

Question: I have Windows 7 and Ubuntu 12.04 in my system and i saw that the default time for os selection menu is only 10 sec, as i am new to Linux can anyone tell me how to increase this time?
Answer:
Press Alt + F2
Type command, gksu gedit /etc/default/grub
change the GRUB_TIMEOUT value to 15 or 20 as required. (value in second)
or Setting timeout to -1 will make GRUB wait indefinitely until you manually select an entry and hit enter,
It should look like
GRUB_TIMEOUT=10
save it. Close gedit. Now open a terminal and run
sudo update-grub
Comment: I required root privileges to edit the grub file else it was giving access denied error as mentioned [here](https://askubuntu.com/q/364008/605028)
Answer: You need to edit /etc/default/grub file by opening a terminal and running this command: sudo gedit /etc/default/grub
You need to set the value of GRUB_TIMEOUT to how long (in seconds) you want the grub menu to appear. GRUB_TIMEOUT is actually the number of seconds before the default entry is automatically booted. If you want to see the menu for 10 seconds which is the default, then do:
GRUB_TIMEOUT=10

Also, make sure that you add # before the GRUB_HIDDEN_TIMEOUT=0 line:
#GRUB_HIDDEN_TIMEOUT=0

Then do a sudo update-grub and reboot.
Answer: I used to use startup manager, as pointed out by Chad--24216, but alas, it's no longer being maintained, nor is it in the repositories.
It has been superseded by "grub-customizer", which while up to date, is also not in the standard repositories. To to add and install it simply do the following at the terminal:
sudo add-apt-repository ppa:danielrichter2007/grub-customizer

Press enter to confirm adding the PPA
sudo apt-get update
sudo apt-get install grub-customizer

Press Y to confirm
You can now launch grub-customizer in the usual ways.  If you ignore the complete list you'll see when it first launches, and just press "Preferences" button on the toolbar you'll get a nice summary dialog where you can change the timeout value and default menu item, as shown below:

Sources:
Startup Manager is dead
Grub Customizer PPA
Comment: Grub Customizer is good but sometimes creates issues when upgrading the distro, So avoid it until one needs it and remember to remove this before distro upgrade
Answer: There are two ways to do it

Start-up Manager (Development discontinues)
Grub customiser  (Not in the official repositories as yet)

Using Start-up manager (available upto 12.04)
Install it by typing:
sudo apt-get update
sudo apt-get install startupmanager

Open up start-up manager
Change the timeout setting to 10 secs

Using Grub Customiser

To to add and install it simply do the following at the terminal (You need to add a PPA):
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
Press enter, then type
sudo apt-get update
sudo apt-get install grub-customizer
And press Y to confirm

Click on the General tab and change the time out to 10 secs

Hope that helps.
Comment: Is startup manager installed by default?. Also I heard, that project is dead now.
Comment: @AnwarShah the op hasnt specified his OS version... the older OS has startup manager, doesnt it?
Comment: In that case, you can clarify the OP. Also, I don't think startup manager was included in the previous releases
Comment: @AnwarShah i'll include the option for newer versions of ubuntu also.
Comment: @AnwarShah edited my answer.. see if it fits what you wanted.
Comment: I am not the OP. But yes, your answer now look good. Thanks
Comment: Sorry guys, I forgot to include that, but I am running 12.04 .    Thank you for your help.
Comment: Thanks For This Answer! I'm using 12.04 And I customized time of GRUB by using "GRUB Customizer"! The Second Way U noted above! Thank U Very Much!
Answer: Web-E's answer is really the best way to do it. However, if you want a GUI way of modifying GRUB that doesn't involve editing a file, you can download an install "startupmanager" from USC or Synaptic. Or with Universe repo enabled, you can open Terminal and install by typing:
sudo apt-get update
sudo apt-get install startupmanager

Comment: startup manager package is not available in 12.04 .
Answer: You need to change the timeout for grub.
Have a look at this guide for really simple instructions on changing grub's timeout / os selection time :
how to change the time for os selection menu in grub
Comment: The link really points to this same question. Funny!


Static Port VS Dynamic Port

Question: In basic networking services, (e.g ssh) why we use statically assigned port number? What are potential problems with allowing services to select their own port in the applications provided by us?
Comment: Known service has to be at a known location (port) for people to access it. It's like trying to shop at a mall that's never in the same place.
Comment: This is pretty basic stuff. An admin can dynamically assign the port in most server applications. You could run your SSH service off port 12345 if you wanted. However, any client that doesn't allow users to select the port... or any user who doesn't know what port to use, will not be able to use your service. You could run SSH on port 80 if you wanted, too, or run your web server on port 22... at the risk of SSH clients or web servers using the default ports being very confused.
Answer: Ultimately you are free to do what you like but avoiding common ports is always a plus and stops conflicts of services.
Answer: Imagine the World Wide Web (www) without standardization of port [tcp] 80 for HTTP or 443 for HTTPS.  Or email if SMTP wasn't typically found on port 25.  How would browsers or mail servers know which port to use to reach the multitudes of servers littered all over the internet?
As @smithy2k3 noted, you can configure whatever port you want, assuming that port is communicated to the client somehow -- sneakernet or email come to mind -- and you're able to traverse your protocol through firewalls that may be inspecting the traffic on certain ports for rewrite -- FTP on tcp/21 and SIP on udp/5060, for example.
Answer: If you were to allow applications to select ephemeral port numbers at their own discretion, there would be no layer of security at the network level.

Static Port VS Dynamic Port


External hard drive not recognised by MacBook Pro.

Question: Recently my segate 1tb external hard drive has been playing up on my late 2013 MacBook Pro with retina. It has been very inconsistent. sometimes it works fine for a day or two or only 2 minutes, and then other times it doesn't even show up. I have looked in disk utility and I cannot find it there. I tried to run 'first aid' on it in disk utility yesterday but got a message saying something along the lines of "cannot perform first aid because the drive cannot be un-mounted. Thanks in advance for your help!
Comment: Since you mentioned that you have a Seagate external drive, the first thing I would do is use the [Seagate Dashboard](http://www.seagate.com/support/software/dashboard/) which has diagnostics tools to validate the functionality of your drive.
Answer: First off if you notice issues with an external drive like you describe that is the drive trying to tell you that it is failing. Hope you have a backup.
If it is not showing up in Disk Utility you could try rebooting the Mac, with the drive attached, a time or two. Power cycling the drive, unplugging it and plugging it back in, all of which might get it working or might do nothing at all.
If you can get it to mount and there is nothing you need on the drive try re-formatting it. If that fails then you definately have a bad drive instead of just a corrupted one.
If you have a third party disk repair utility (I like DiskWarrior) and it will see the drive run that.
Honestly it sounds like the drive is dying and needs to be replaced, either under warranty or by buying a new one.
Answer: There is an app named 'Mountain' that will let you mount or unmount your drive. Even if its malfunctioning.  you may try mounting it with this app.
Comment: Welcome to Ask Different!  We're trying to find the best answers and those answers will provide info as to why they're the best.  Answers should be self-contained so explain why you think the answer you provided will solve the problem or is better than others out there.  Providing links as supporting information can also help the OP, and others, find additional info for themselves.  See [answer] on how to provide a quality answer.


What are the epistemic problems or justifications for obtaining knowledge from StackExchange sites?

Question: What philosophical problems are there with obtaining knowledge by picking the correct or closest answer from a small set of solutions? And further, what are the problems/justifications for judging knowledge based on the democratization of questions and answers instituted by such methods as "up-ticking" a question or answer? Can these two systems, when fused into a Q&A site, serve to allow the user to find knowledge in a justifiable way? Or must each piece of knowledge -- no matter it's answer status or number of up-ticks -- be rationally considered separately in its own right?
Answer: Answers to questions on StackExchange sites seem to fall under the general rubric of "testimony" and thus inherit the problems and strengths of the literature on the epistemology of testimony.
When can you know something that is reported to you as opposed to something you perceived yourself? Hume's answer to this was something like "Well, we kind of know from past experience that people are typically trustworthy" (This from the guy famous for undermining induction! I know!) Here's the passage in the Enquiry:

The reason why we place any credit in witnesses and historians, is not
  derived from an connexion, which we perceive a priori, between
  testimony and reality, but because we are accustomed to find a
  conformity between them

There's something really classy about spelling "connexion" with an "x" like that. Damn.
The problem for this justification is, of course, that the conformity between "stuff I read on the internet" and reality is much less frequent and uniform than the conformity between reality and "stuff my friends report to me sincerely". So there are additional problems due to the nature of the medium.
Bayesianism is an approach to epistemology that has methods for dealing with problems like this: problems of gaining knowledge from faulty signals.
Comment: Maybe it's possible to argue that the Stackexchange sites are some sort of Bayesian calculator?
Comment: Since when did 'popularity' or the 'fifty-one-percent vote' determine truth?  And, don't tell me: "Truth like justice is in the eye of the beholder."  Or, "Whose 'truth' is it?"  Or, "What truth?"  Or, "What *is* what?"  I'm not finding your site to be helpful at all.  Stack Exchange answers are symptomatic.  The 'problem' is the typical 'ideology' evidenced by both the 'self-educated' (which seems to be the overwhelming case with *Philosophers Stack*: i.e, too many "Johnny boys"), and public education alongside Marxian academia in today's post-modernist, politically correct Left-Wing America.
Comment: I think you do have a general idea of what "I'm talking about."  Epistemic problems, justifications, knowledge.  **Stack Exchange** is an interesting site; but the best place for information and "knowledge" is not the Internet (as an example, you should rarely use Wikipedia); a "better place" is your local Junior College liberal arts library.
Comment: No I think the Bayesian calculations are done by the agent having the beliefs. What the upvoting and reputation systems do for the site is attest to the trustworthiness of the signals (the answers). It is then up to the agent to work out how her beliefs ought to change in light of the signals.
Comment: @DarcyDavis It's not about determining truth: it's about working out what are reliable _indicators_ of truth. The basic idea is "if lots of people believe $x$ then $x$ is likely to be true", not "If lots of people believe $x$ then $x$ is true". And as I said, the indicators of truth in this sort of case are defeasible, equivocal and not on such solid ground as one might like. As to the second half of your comment, I have _no idea_ what you're talking about.
Answer: Obviously, the way one approaches this question will vary depending on the epistemological tradition one is working within.
From the standpoint of the Nyāya school of classical Indian epistemology, there are exactly four epistemological warrants (Pramāņa -s):

Direct Perception
Inference
Analogy
Authority

Now, clearly Perception is not in play in this case, but the other three form the means of justification available to us when reading an answer.
Inference and Analogy are relatively straightforward: if the argument in the answer is logically cogent and sound, we can accept the answer, and we can similarly evaluate the answer by means of analogy to other knowledge we already have. Neither of these are specific in any way to StackExchange, of course-- they are the means we would use to evaluate any answer given to us by any third party.
What is somewhat different here is the means of evaluating authority.  Although external credentials (such as graduate degrees or publications) are not made prominent here, the upvoting and reputation system give a means of evaluating the relative authoritativeness of the answer (and answerer) in the eyes of the community.  And that community evaluation, of course, is in turn based upon the same list of Pramāņa -s  as above.
Answer: I can think of one merit. For instance, when there some people who are living at geographically and historically speaking different places from the majority of people ( which is, in my assumption, the "Western People" ), like people from India, People from Russia, people from Africa, people from ME, people from Asia, for these who are in the majority group, I think these different people can serve well enough here since they can give the majority of people probably very near original source, which, I assume personally would be a language barrier. If you would like to know something peculiar about Buddhism, oh yes, the best choice would be to ask people from India, since after all, Buddhism was born and has been "advanced by" for a long time there ( but actually not at today's India but in terms of cultural influence ). If you would like to know Chinese thoughts, the best way is ask Chinese without doubt ( is there anybody here...? ).
One "problem" or potential demerit is that if you are not interested in the questions and answers, then it would not be helpful to you and you should go elsewhere.
If my answer does help in any kind of ways, I will feel happy.
Comment: Kindly allow me to give thanks to the person who edited.
Answer: To consider this objectively one must keep in mind when seeing the result of votes, on how they are created. Rationally one must consider that the votes on this site came from its rules, that is, because of them to get votes you have to get reputation and objectively it is just reputation. The system provides an objective valuation as far as the members are being objective. If the majority of the site are objective, the numbers are objective within their own definitions based on their causes: the rules.
Answer: There are debates in social epistemology as to the epistemic value of going with the numbers. Some hold that weight of opinion is only good justification if each individual comes to a conclusion independently and if they are sufficiently expert in the topic rather than being "nondiscriminating reflectors". But on the other hand, it can be proposed that some epistemic weight might be given to a nondiscriminating reflector Y's agreement with X (the expert) if they have some ability to identify experts (meta-expertise):

The novice's confidence in X's expertise concerning hypothesis H is rationally
  increased by his or her confidence in Y's meta-expertise

(Coady, 2012). On SE, there are clearly voters with varying levels of expertise - though it might be argued that all members of the community have at least the ability to recognise attributes of quality answers.
My own work (Matthews, 2014) suggests that those with higher levels of knowledge, if voting blindly, will tend to agree with the high ranked answers. Those with lower levels of knowledge will tend to pick more randomly when the voting cues are not present. This implies that the system on the whole works well as long as there is sufficient expertise among the voters.
We should also be aware that there are some sources of bias in SE sites that can mean that the highest voted answer is not the best. There is the well-known first mover advantage where the earlier answers gains votes and hence reputation for the answerer (the "fastest gun" effect, see Mamykina et al, 2011). This implies that it's always worth checking newer answers as well as highly-voted ones.
Coady, D. 2012. What to Believe Now: Applying Epistemology to Contemporary Issues
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-EHEP002800.html
Mamykina et al 2011. Design Lessons from the Fastest Q&A Site in the West
http://www.cs.berkeley.edu/~bjoern/papers/mamykina-stackoverflow-chi2011.pdf
Matthews, P. 2014. Use of credibility heuristics in a social question-answering service
http://www.informationr.net/ir/20-1/isic2/isic27.html#.VZpVIUaHhVU


Is it possible to check Active Directory logins?

Question: I'm not very familiar with Active Directory and I've been trying to figure out if there's log files to check that would list user logins with times to check up on unauthorized access. I'm running Active Directory in windows 2008.
Answer: You can enable auditing through the group policy, there are options to audit successful and unsuccessful logins.  Keep in mind, if you have more than one DC, logons can be handled by any of them, so a user may log into DC 1 today, and DC 2 tomorrow.  Also, services, applications, and other things produce login audits, so it does tend to get a bit cluttered.
You would find the audits in the Security log under the event viewer (Windows logs node in 2008).
Answer: Provided you have the logging of logon events to the security event log enabled, you can parse through the event log looking for logon attempts.  A tool useful for this is Sysinternals  PSLoglist.exe., and you should query domain controllers and file servers for activity.
There are several different 5xx and 6xx event id's for you to look for. You'll set the command line up like:
<code>psloglist.exe \\domain_controller -d 1 -i 680<add more here> -s security
</code>
You can also use a filtered dsquery.exe query to look for user attributes like lastlogon time.
Answer: The post above is correct. DC's in a site will have eventlog entries that represent the logons it has serviced. This can be misleading due to the reasons that post mentioned...along with some others like Kerberos ticket renewal. To really get a good picture you also need the security logs from your workstations. This can be kind of a pain. If they are XP, then I would batch it and load it to your central log host during slow hours. If they are Vista or higher you can configure event forwarding. This has some prerequisites, but its probably the best option.


How can I increased mileage of my Bike

Question: I have a Honda CB Shine 125cc bike. When I purchased it, it was giving me mileage of 50 km/L, but now it is reduced to 40 to 45 km/L. How can I increase the mileage of my bike and increase it up to 55 km/L and above?
And what precautions needed for this.
Answer: Here are some generic tips for increasing mileage:

clean filters: air and fuel filters become restrictive when they get dirty. Clean them or replace them, depending on your engine's design.
clean fluids: a happy engine is an efficient engine. Frequent oil changes help.
spark plugs: inspect them and replace them when necessary. They set your fuel on fire, make sure they are in good shape so that they can do their job well.
easy on the throttle: do not drive like the bike is on fire. Smooth is efficient.
easy on the revs: Upshift early whenever you can, downshift late whenever you can.
mind the road and the weather: the best advice I was ever given was "drive downhills and downwind all the time." Granted, this last bit of advice is totally impractical, but it works.
Comment: I once heard the advice "drive like there's a rotten raw egg under the accelerator and if you push it down, you'll break the shell and stink out the whole car"
Answer: Anticipate the road more.  There is no point rushing up to a light that is red, or is likely to go red real soon.
Idling stopped is 0 km/l so avoid idling in traffic... pick times of the day where the traffic is not going to be stopped.  (assuming your location disallows lane splitting)
Contentious one, avoid engine braking.  Use the handbrakes more.  Of course this decreases fuel usage but increases brake wear.
Draughting saves energy too - but is generally too dangerous, and is only of benefit on the open road.  Round town at 50 km/h its of minimal benefit on a motorbike.
Lighten your bike saves fuel.  There's fewer places to stash crap on a bike compared to a car, but check all the storage and empty it of non-essentials.   Lightening the rider helps too.  What you need to carry is a judgement call.
Finally one of the biggies that was not yet mentioned - Tyre pressure  Higher pressures suffer from less rolling resistance, but give a smaller contact patch with the road and therefore less grip.  Harder tyres give more road noise and buzz too, which is no fun on chipseal roads or gravel.  Softer pressures are slightly more likely to puncture, and will sap more energy as you ride by slightly deforming the tyre.   No hard and fast advice, but try adding 5 PSI and dropping 5 PSI and compare.
Extra - good records helps.  Getting X km off one tank and X+50 off the next is a bit hard to compare if the first tank was pootling about town and the second was one single big open-road/highway trip.

How can I increased mileage of my Bike


Left France but forgot to inform the Centre de Finances Publiques

Question: I'm an Italian national. I lived and worked in France from September 2010 through December 31, 2012 then moved to the UK. When I left France I forgot to tell the Tax Authorities that I moved abroad (but in any case I haven't perceived any income in France in 2012 as my employment was terminated at the end of 2011). I just received the avis d'impôt 2015 where they require me to pay 6,000 euros in taxes for 2012. What would be the best way to clarify this?
Comment: Just to clarify: Because France system for tax on incomes is based on declaration (and not directly withdrawn from your salary), the taxes you pay in 2012 correspond to the incomes for 2011. Isn't the *avis d'impot 2015* asking you to pay the income tax 2012 for the incomes perceived in 2011, that for some reason you didn't pay in 2012 (while in France)?
Comment: Possibly related to http://expatriates.stackexchange.com/questions/6124/french-taxes-have-not-received-any-documentation-and-i-have-moved-out-of-the-co
Answer: The best way to clarify this would be to get in touch with the Centre des Finances Publiques that sent this request to you and explain them the situation, pleading good faith. There probably is an email address in their contact information.
If you are not fluent in French, you might need help from a native French speaker to write your message.
There's a possibility that even if you had no income for that period, there's a a penalty for not filing the tax documents on time. Or they are asking for the 'Taxe d'habitation' for that period.
Comment: The penalty is computed as a percentage of the tax due (plus interests) so there is no penalty if no tax is owed (if you proved that to the tax office's satisfaction that is).
Answer: Failure to file a declaration often (always?) ends up with the tax authorities

bugging you to file;
deciding how much you have to pay, based on the previous filing and notifying you;
and, if they can, take the money directly from your bank account [ouch]. Been there done that.

I suppose that when you left France you closed your bank account – so the tax office won't be able to help itself to your monies. However, it would be better to clear up the "misunderstanding" by communicating with them. Explain that you had zero income in 2012, and when you left France, you forgot, oops, to let them know, and weren't able to file a tax return.
I, however, have had a not so good experience with that route. Despite my best efforts to explain my situation, the tax authorities decided that they didn't care, or weren't convinced, and took the money anyway. So the second time around, when I sold my flat [taxes were paid on that, so it wasn't an issue], and closed (with great difficulty) my bank accounts, the tax office kept chasing me for a year, demanding this and that. They even called my mom, in another city. In the end they gave up, and it's been seven or eight blissful years. So if your attempts at negotiating/explaining don't work out, I would recommend to drop the matter entirely, and file their demands in a nice folder. Uncivil servants are not that industrious after all...


How do I protect my paper wallet from use by a different human who has used a random generator?

Question: Since millions of people use Bitcoin and Bitcoin Wallets that use their own addresses use several addresses per day, it is obvious that generators can generate the same characters for the Bitcoin address multiple times. So please therefore simply tell me how one would prevent others from accessing or spending the coins that are stored at my paper bitcoin address.
Comment: "that is improbable so therefore who cares": **This is the entire point!** Cryptography never makes anything truly impossible, but it can make it so improbable that you no longer worry about it happening.  You have to understand and accept this before you can go on to understand anything else.
Comment: try to focus on the question, not the rant. the current 'question' is 90% rant.
Comment: My first Google result for "bitcoin address duplication" is https://bitcoin.stackexchange.com/questions/23268/what-if-duplicate-wallet-addresses-are-created which links to two additional dupes.
Comment: The point of ignoring probabilities here makes literally no sense. You could just as sensibly ask about physical money you held simply flying away spontaneously due to random atomic vibrations and quantum physics. Yes, it could happen, no, it wont.
Comment: I could also spontaneously combust. Statistically SOMETHING could trigger it (I agree, super unlikely... but still). I don't carry a fire extinguisher with me just in case (and I assume you don't)... it's all about risk management and understanding what "1 in a trillion" (or whatever) really means. I am aware that in the world of bitcoin, it's FAR LESS than 1/trillion btw...
Comment: I think that "having a probability greater than 0" is a poor definition of "possible". After all, the probability that I will grow wings and become an airplane tomorrow is greater than 0, but that isn't the sort of thing you'd call *possible*, is it? So, don't be so sure that it's *possible* for someone else to end up with the same private key that you ended up with.
Comment: @Raven: try to edit your question into open–ended wording, and you might make it easier for the community to find a proper answer. Maybe the question should be "how possible is it to duplicate an address randomly". There are roughly 20 posts on this forum here and in bitcointalk. They explain the math, and people would be more than happy to provide corresponding links. With you wording this is nearly impossible....
Answer: "Improbable" is an understatement.
There are 2256 possible keys.  In the entire universe, there are estimated to be "only" 2100 atoms.
So the odds of someone else ending up with the exact same address/key as you is far, far less than the same atom, out of the entire universe, being randomly picked twice.
If you are worried about an address collision, here are things that should be more worrisome:

Gamma ray burst wiping out all life on earth.
Sun unexpectedly going Supernova
Rogue Blackhole swallowing the solar system
An asteroid hitting the earth at the same time as nuclear war breaks out.

On the list of things to worry about, an address collision just does not show up.

You say that "millions of people use Bitcoin and Bitcoin Wallets that use their own addresses use several addresses per day".
<code>  100 Million of people
  100 addresses per day
  365 days / year
* 200 years
-------------
Less than 1 Billion addresses used in the foreseeable future.
</code>
1 billion is about 230.
Which means that in 200 years, the chance of a collision is somewhere around 1 in 2256-30 or, 1 in 2226, which is still way more than atoms in the universe.
You're easily safe for at least 200 years.
Comment: How do you protect your paper wallet from mice nibbling on the paper?  As far as probabilities go, I'd be far more concerned with that than random number hits.
Comment: Did you account for the birthday paradox in your last section?  I think the real probability of any collision occurring (for anyone, not just you) is 2^96.  We're at least getting down to the number of atoms in the universe.  Or, if we prefer to think in positive terms, the probability of *someone* having a collision happen in the next 200 years is equivalent to *you* winning the Powerball lottery 4 times in a row.
Comment: Also, studying the [Large Bitcoin Collider](https://lbc.cryptoguru.org/trophies) project might make it seem more of a 'real' problem than one might distil from this answer.
Comment: [Slightly less than 2^256](https://bitcoin.stackexchange.com/questions/38108/order-of-group-of-points-of-secp256k1) keys, but 2^160 addresses and forgery only requires matching the address. Still infeasible.
Comment: https://motherboard.vice.com/en_us/article/nzpv8m/the-large-bitcoin-collider-is-generating-trillions-of-keys-and-breaking-into-wallets  "the project has generated over 3,000 trillion private keys and ... has found ***three*** that contain bitcoin.";   "the brute force strategy they're using poses no threat to anybody's bitcoin."
Comment: @abelenky [More than 3 (10+)](https://lbc.cryptoguru.org/trophies) as of the writing of this comment.
Comment: Nope, I only see 3.  The rest you see all note they are part of the "Puzzle Transaction", a sequence of addresses that was deliberately created as a puzzle in a non-secure manner, and is meant to be solved.
Answer: It seems like you already know the answer, but want to hear something else. So, you really have two choices:

Accept that modern cryptography relies on improbable outcomes. It's physically impossible to create the identification system that you describe.
Reject this reality and substitute your own.

If you choose (1), and would like to know more, there are tons of resources - identities are established by creating SHA-256 hashes in bitcoin. More importantly, there is no "unique identity" principle in this universe, since information can be replicated by chance or by effort and elementary physical particles are indistinguishable.
If you choose (2), I don't have a good answer for you.
Answer: The generation of private keys is made randomly. Therefore, it is possible for someone to generate the same private key as you did. In your question, you heavily insisted that you did not want an answer on how improbable this is. The answer is : You cannot protect your paper wallet from someone having incredible chance and getting the same number generated as you did.If you do not trust the way private keys are generated, you should take a look at this article.

So – for all those doubting the security of 2^256 collision chances, there's the number: There is a 1 in over 115 quattuorvigintillion (that's a 78 digit number) chance of finding a collision. This number is bigger than the number of atoms in the perceivable universe
Answer: The idea of ignoring sufficiently small possibilities is fundamental to BitCoin, and if you have a problem with it, then you shouldn't be using BitCoin (or anything else that involves a finite password space). If someone were to simply create a forged transaction from your wallet, put it in a block, and find a hash for that block, being able to do that by random chance would be likelier than picking the same keys as you. Randomly choosing a name and social security number and having it match yours would be likelier. Randomly choosing a credit card number, expiration date, and cvv, and having it match yours would be likelier. You are waaaaaaaaay more likely to lose your BitCoins from your wallet being trampled by a zebra who's been spooked by lightning hitting someone who just won the lottery than from someone randomly choosing the same keys.

If you consider this a "stupid question", it apparently isn't, because Google has literally no results whatsoever about this.

That logic is valid only if it is reasonable to expect Google to have answers to every stupid question.
Answer: The Large Bitcoin Collider was already mentioned in a comment, but it is worth mentioning in an answer also.
These are a group of people out there doing this now, going through random BTC private keys looking for wallets with money in them. So far they have found private key for three wallets, worth 0.0079 BTC, 0.0001 BTC and 0.00001 BTC. In addition they've found several keys related to a puzzle transaction, which apparently used intentionally guessable keys.
Their current search speed is 1550 Mkeys/s. If you have a single wallet with a random private key, this means that by average you'll be hit once every 3 · 10³¹ years. So for an individual user, the statistical risk is insignificant. There are 15 millions wallets with money in them, so even the chance of hitting any wallet is just once every 2 · 10²⁴ years. Their hits so far are much higher than this, which suggests not all keys are as random as one would expect. Someone may have even made the addresses intentionally for LBC to find, but no-one knows.
The real risk is in your random generator that you used to generate your private key. A few years back, Debian's OpenSSL package had a very bad random generator bug. This made it trivial to guess all private keys generated with it, yet it took two years until the problem was publicly detected. I would be somewhat wary of using less commonly used or experimental software to generate private keys, a single bug could make the wallet easy to compromise.
But as long as you use a well designed software to generate the key, you should be safe.
Answer: What all of url don't realise is that is not impossible for hackers to brute the crap out of private keys, with computer processing increasing rapidly it's definitely not IMPOSSIBLE, to put the record straight, but then again that's vulnerability as being around since computers started to exist.
Comment: Yes, it is impossible.


Should I have a text size widget for accessibility on a charity website?

Question: I'm a developer at a small web agency that works primarily with charities. We tend to put a simple textsize widget on every site (eg. top right on www.embraceme.org). I find myself wondering if that's necessary: if someone has difficulty seeing, then there's a number of tools at the OS/browser level to help them out. If each website reinvents the wheel then that's a new tool the user has to keep relearning (not to mention extra and unnecessary complication on the site). We don't have an accessibility/usability specialist, so would love to hear people's views on this.
Comment: I side with your thinking these days, though have no data. But yes, all browsers can resize pages just fine, so it would seem that having to build one's own widget is redundant and potentially confusing.
Comment: Who is the primary audience of the website? FWIW, this question may help: http://ux.stackexchange.com/questions/703/font-size-amender?rq=1
Comment: @MattObee I was looking for a fairly general answer - I don't have a particular site (and audience) in mind. That other question is perfect, thanks so much: I'll take a look through now.
Answer: Providing such font size options within individual websites isn't as important nowadays than it used to be (for instance when IE6 was a more common browser as it didn't really have a suitable font resizing option) but that doesn't mean it no longer has its place; it is particularly useful if the target audience for the website is more focused to users with disabilities - such as for the London 2012 Paralympics.
However your main priority with font sizes is to ensure you put your site together using correct modern HTML standards rather than focusing on minor 'widgets' here and there.
The main accessibility requirement around text resizing is that:

WCAG 1.4.4 Resize text: Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality. (Level AA)

This can be achieved in a variety of ways, all using good HTML standards. For example, use standard readable fonts, don't set your default font size too small, keep your fonts in ems instead of px so that they resize correctly when the user adjusts the font size via the standard browser controls, and keep your layout adaptive / fluid so the content doesn't expand out of the screen / containers when the font size is increased.
There are some good suggestions about how to keep your text accessible at the w3c site - Understanding SC 1.4.4 Resizing Text as well as at webaim.org
Check your target audience for your project. If the users are more likely to benefit from the in-page font resizing due to minor visual disabilities or those that suffer from dyslexia, or (and I hope this isn't the case anymore) if they're locked into using IE6 then yes, it's probably going to be useful to provide that option, but for current web design it's more important to get your code in shape and use good HTML and you can let the users take control of how they want to experience the web.
Comment: Thanks, very useful. Could you expand on why dyslexics and those with minor visual disabilities would benefit more from an in-page tool rather than browser/OS-based? Thanks!
Comment: @Andy If your site is particularly targeted at users with visual disabilities then you should make more effort to accommodate their needs (not just providing font resizing options, but contrast switching, and even a choice of fonts). Just like you would cater a children's website to the target audience, you should target a disability website to that user, but in general the standard browser controls are suitable because the user sets it per-browser, not per website.
Comment: Thanks for clarifying, I'd slightly misunderstood the thrust of that sentence.
Answer: I recently attended a Nielsen/Norman Group conference and this question was asked.  The answer they gave was that in the many usability tests that they have done, very very few, if any, users ever actually used the feature.
That said, if you did want it to be used, placing it in the upper-right location makes it much less likely that a user will find/use it.
You might want to try testing some different placements or configure GA Event Tracking to see if people are using the feature at all.
Comment: My concern with usability tests when it comes to accessibility features is that you're not testing the audience that would benefit from this feature. For example I bet nearly everyone on the test there didn't test using a screenreader, or didn't notice that the images had ALT tags, but that doesn't mean we no longer should consider those users that do need these.
Comment: Generally speaking users have a mental model that says "the top right area is for utility links", so if a user was looking to login, for example, they would look up there.  Or in this case, the shopping cart is a natural place to look.

However for something like a text-size incrementer, they would not normally expect it to be there, and when hunting/scanning will look more to the left side of the page.  That said, TEST! :) I could be wrong.
Comment: Exactly what I was looking for, thanks! I'd love to use GA to see how much it's used (and try various layouts) but I don't think we'd convince our clients to fork out for that! Out of interest, what's wrong with putting things in the top right corner?
Comment: Thanks, I hadn't considered that; it makes a lot of sense.
Comment: I should add the clarification that they were answering the question within the context of usability of the text-size feature in the page itself.  They said their test users would use their browser's zoom feature to increase size instead.  But I agree when testing accessibility features it is not valid to say it isn't needed if none of the test subjects would use the feature anyway.
Answer: If you don't set the font size of the main text, it will use the font size specified in the browser settings.  It looks like your site does not set this so it will use browser settings font size, making a text widget somewhat redundant.
(So in the future ensure it remains this way, the font size for the main text is not set in the CSS to keep it working the way it is.)
Comment: Thanks, but I wasn't really asking how to create a resizable site; I'm more interested in whether people feel it's still important from an accessibility point of view to have a text size tool on-site.
Answer: If you built the site in that way that the font-size (*) can be increased/decreased by the user's browser, there is no need for a widget.
*: Note that font-size zoom is not the same as the page zoom (the latter is the default in many browser today, but it can be switched to font-size zoom by the user).
If your site's font-size cannot be changed by the user's browser (because of a special way you built your site, which should be a very rare case), you should provide a widget.
But if you provide a widget, you should make sure that it works for all of your visitors. I can't use the widget on embraceme.org, because it requires cookies and JavaScript. If you can't built it that way that it works for users with disabled JS/Cookies, too, you should hide it for those.
Answer: I'd say you include it, not on the right top though. Why? Because older people using the web might not understand very well how to change settings on their browsers and something they can see available right there would be more helpful for them. It doesn't interfere with magnifier software such as Zoom Text, however I don't know how would it interact with screen readers such as Jaws.
Comment: Why not on the top right?