Why is a chargedown not regarded as a knock on in Rugby Union?

Question: Generally in Rugby Union when a player knocks the ball forward from their hands without making a clean catch, a scrum is called for a knock on. But when a player kicks the ball and the ball is knocked down by an opponent, no knock on is called and they are able to gather up the ball. Normally a kick like this occurs as a defensive action close to the try line, so a charge down often results in a try.
Answer: Law 11 of the Laws of Rugby Union specifically exclude a charge-down that happens immediately following a kick as being called a knock-on or throw forward.
I think this has been a law in Rugby for a long time and is not a recent innovation. Before 1958 it was even possible to rush the the kicker and charge down a penalty kick from immediately the time the ball was placed on the ground. To avoid this, under these older laws another person used to place the ball as the kicker ran up - a bit like how someone places the ball for the kicker taking a field-goal or a point-after in American Football.
So the charge down has been with the game for a long time, but why?  I think as Harley Holcombe's answer says, that this is to allow pressure to be put on the kicker. It allows someone rushing the kicker to have an opportunity to gain regain possession.
They cannot tackle the kicker (because they don't have the ball), and picking up the ball in the process of being kicked is more difficult and sounds kind of dangerous.  So a chargedown law adds excitement and unpredictability in taking tactical kicks - re-balancing the risk and reward for taking a tactical kick.
Mostly it fails as kickers are wary of the tactic, but it is still worth it for the attacking side because it can force a mistake or the kicker taking a less ambitious kick.
Comment: Blocking a kick is a common method to avoid kicks to go further into the defense. In fact is so valid, that when you call mark the opposite team could leave a player in front of the kicker, or when you have to kick from the 22 yards line,  the opposite team could leave a player in front of the kicker, if is not inside the 22 line..
Comment: @gbianchi - Agreed, but that is the whole point of the question, normally a knock-on would result in a scrum being awarded to the other team, a charge down is the exception.  Blocking/stopping the ball from a kick further down the field with your hand resulting in a knock on would lose you possession and would count as a mistake.  The only exception is a charge down immediately in front of the kicker.  A charge down can be for both defensive and attacking reasons.   You might do it to stop someone advancing or scoring a drop-goal, but it is often used when pressuring in attack too.
Answer: I believe this rule was brought in (to rugby league at least) to encourage charge downs. This puts more pressure on the kicker and encourages the tackler to attack the ball, rather than hitting the kicker, who may not be ready for it and could get injured.
Another reason to have the chargedown rule is that a successful chargedown can add excitement, check out some examples on YouTube.
Answer: The question "Why is a charge down not regarded as a knock on in rugby union?" can be answered as above, by quoting law 12.  But my answer to the question relates to the principles of the game as well as the laws.
There are two kinds of infringements that can occur on a rugby field, technical and intentional. Technical infringements are usually sanctioned with a scrum or free kick, intentional infringements are sanctioned with a penalty and possible admonishment of a player and a sending off.
So, is the charge down of a kick an infringement at all? If so, is it a technical infringement or intentional? Or, is a charge down of a kick a skill specific to rugby union? (and other codes such Australian rules, Gaelic football and rugby league).
Has an infringement occurred around the ball, the ball carrier or team mate of the ball carrier? No.
What has happened is an opposition player has, with good timing and skill and bravery, managed to get their body in the way of the flight of the ball and, through no act of foul play or other illegality they may benefit from this action.
A simple rule of thumb when refereeing a game of rugby union. Penalize negative actions, reward positive actions.


Name on driving license slightly different from Passport

Question: I am traveling to Spain in summer and plan to rent a car online (Sixt, Avis, Budget etc.). I have a Tunisian driving license plus an international version (which is just some worldwide recognized translation). The problem is that my name on the passport is "Mehdi" but when translated from Arabic it can be either "Mehdi" or "Mahdi". Unfortunately, when my driving license was issued several years ago, the name "Mahdi" was written on it. Since I don't live in Tunisia, I didn't really have time to fix that. How strict are regulations when it comes to one character difference? Would I have problems when picking up the car? What is better to do, write "Mahdi" or "Mehdi" when booking a car online?
Comment: I would go with the name on the Driver's license, as that is the document they are more likely to care about. As a precaution, I would take the phone number of the Tunisian Embassy in Madrid for the rental agency to call to verify they are both valid transliterations, just in case, but I doubt you'll need it, especially if the photo matches.
Comment: Nobody ever asked me to show a passport or ID when I rent cars (I rent about 20 a year, in many countries in the world). All they ever care about is that the name on your credit card matches your drivers license, and that your credit card works.
Comment: Well that would be a big problem then
Answer: This is unlikely to present a problem.

The passport and driving licence have nearly identical names and matching photos, which offers strong proof that you have the right to drive in Spain.
The fact that names can be translated differently into English is fairly well known.  And if anyone raises this as a concern you can argue convincingly that the names are not actually different, only the translation is different.
The person reviewing this will be a low-level employee at the rental car desk, who, in my experience, is unlikely to be a stickler about these sorts of things.  They will probably just dutifully copy your documents without noticing or caring about the discrepancy.

However, if you want to be completely sure, contact the rental company in question.
I'm not sure which name would be better to enter on the application. It may be best to choose the drivers' licence, as suggested by a commenter, but I don't have any real basis for that.  I would perhaps choose based on the proximity to other information when filling out the online form.


Cheapest way from Hussein bridge, Jordan to Tel Aviv, Israel

Question: I am looking for transport from the border crossing at Hussein bridge to Tel Aviv.
The most important factor is price.
Answer: The cheapest way to get from the Hussein bridge crossing to Beit She'an is line 16. You can see its route here and the time table here.
But, it's somewhat complicated because the bus that goes to Beit She'an doesn't stop at the border crossing. So the best way to know what bus you need is Google Maps, search for "צומת נהר הירדן" you can use this link. Once you get to Beit She'an you can take a bus to Tel Aviv, I recommend using Google Maps for this as well. There is bus line 845 directly from Beit She'an to Tel Aviv or you would need to take a bus to Afula (411) and from there there are buses to Tel Aviv (825), and other routes according to the time of departure.
Few important notes:

The border crossing is open on Saturday, however there is no public transportation on Saturday in Israel, so if you plan to come on a Saturday, you would have to take a taxi, which would be very expensive.
The same goes for Friday, public transportation works only half a day on Fridays and some lines have different schedules on Fridays while some aren't active at all, so take that into consideration as well.
Line 16 has only 6 buses a day, which means that you might have to wait for a long time for a bus. The bus station is located only 6.6 km (according to Google maps) from the Beit She'an central bus station, so it may be acceptable to take a taxi for this short trip, and then use public transportation from there. All according to your preferences and circumstances.

If you want other options other then Google maps, you can use www.bus.co.il which is an aggregator of all the bus companies, here is an example of how to get from the border crossing to Tel Aviv leaving at 8:00 on February 29th, 2016.
A somewhat related side note:
I personally use only Google Maps to find buses and trains, as I find it more comfortable, faster and more informative that using the sites of the actual bus companies. So I highly recommend using it during your visit whenever the need for public transportation arises, especially when in a new place as the map will not only tell you the time, but also the location of the stations and will guide you to them.
 I'm not affiliated with Google in any shape or form, I'm simply sharing my real life experience,
Answer: For Israel public transit, http://www.bus.co.il/ is invaluable. I found  Google Maps unusable in Israel without knowing Hebrew. This bus website works well even if you only speak English and integrates Google maps. Here's how you'd do your request, first click the marker:

then drop a pin on the popup map:

Click through for connections then more connections to get:

And the more details link next to each itinerary (some are repeated) will include everything you need to know.
Comment: Why the downvote?


Can a copy of the blockchain hold private information?

Question: I want to run a daemon on another machine, and I was thinking of copying the blockchain I already have (copying the entire <code>.bitmonero</code> folder). I'm curious whether any private information may be leaked by doing that, such as information about the machine that this blockchain was synced on (IP, name, OS...) or information about wallets that used this copy of the blockchain.
Answer: The blockchain itself will not (beyond its endianness), but some other files might: the logs, in particular, might contain paths specific to your computer (not saying they definitely will). The p2pstate.bin file will contain your node's peer id (though this is now reset on every restart), and may also leak information on the version of boost it was built with. That's all I can think of right now. No wallet information will be there (unless of course you chose to store your wallet there).
Comment: So, should copying only the `lmdb` folder be safe?
Comment: That should be fine. There's a lock file there, in addition to the db, but I don't think it will leak anything beyond possibly endianness and bit depth (I don't know whether it does or not, that's just abundance of caution). But then the lock file is useless to the other machine, so might as well copy just data.mdb in the first place.


How do I denote someone weight

Question: How do I say my weight? In which SI units? I see people are using Kg as a unit of denoting weight from my childhood. Answer this question "What's your weight?".
Comment: this is a much better question than the other one...
Comment: There is an important note at the top of the wikipedia page:  "In law, commerce, and in colloquial usage weight may also refer to mass."  Rest assured the topic has been the subject of unending debate.
Comment: @agentp engineers are very clear about mass and weight....
Comment: @SolarMike sure but we also need to communicate with non engineers and so understand in many contexts "weight" actually means mass.
Answer: Weight is a force and is expressed in Newton (N). Mass is expressed in kilogram (kg).
However, in informal (non-scientific) language, people often express weight in kg, although this is not correct strictly speaking.
The relation between the two is $F=mg$, with $F$ the weight (N), $m$ the mass (kg) and $g$ earth's gravity constant.
See also here.
Comment: okey I understood the concept
Comment: I think it would be less confusing to say "in informal (non-scientific) language, people use the word "weight" as a synonym for "mass". In science and engineering, "weight" and "mass" are *always* different concepts.
Comment: yeah  i got it but if somethings weighs 2kg in weighing machine does that mean 2N
Comment: No, $2\mathrm{kg}\cdot9,81\mathrm{m/s^2}\approx 20\mathrm{N}$.
Answer: As this is an Engineering stack we use the prescribed units, mass is in kg and weight is in Newtons.
This is a common misconception by the masses (great unwashed...) and it is also covered in this question :
Force Required to Lift a WEIGHT of 1Kg
It is also obvious in various phrases such as "I am gong to boil the kettle" which is assumed to mean boil the water that is inside the kettle and not put the kettle in a big cooking pot and boil it...
Comment: So if i say 1 Kg of weight does that mean 1N
Comment: 1 N is approx 100g (102g), 1kg is 9.81N, don't mix them...

How do I denote someone weight


What counters AP Kog'maw in mid?

Question: I played a few games over the weekend and I kept seeing a bunch of AP Kog'maw players and they were giving me a really hard time in mid. What are some solid counter picks or strategies I could use against this in middle lane?
Comment: Akali is my personal favorite.
Answer: V184.108.40.206
Void Ooze slow reduced: 28/36/44/52/60%, to 20/28/36/44/52%.
Any champion that can get up in his face is pretty useful.
For example, champions such as Fizz, Akali, Jax, and Irelia. Bursters are also very strong, such as LeBlanc, Veigar, Annie, and Brand.
However, especially in solo queue, you never know if someone will go AP Kog; so countering with a certain champion does not always work unless the game mode is draft mode or ranked.
Therefore, I will give tips on how to counter a difficult opponent by other means than just picking the right champion.
So how do you counter an AP Kog, in the event that you chose a champion that does not counter him well?
Use your jungler
AP Kogs tend to play aggressively, often trying to pick up early kills because of the fact that it's harder to passively auto attack farm without lots of attack damage.
Call in your jungler to help gank. If the gank is successful, the extra gold/exp can be a huge advantage. If Kog does not die from the gank, forcing a recall is also very beneficial.
Be Aggressive
But not too aggressive. Make sure you are not pushing the lane too hard, or else the enemy jungler can kill you easily. I am saying you should be aggressive because of Kog's high range. If you stay back, Kog can easily zone you, and out-farm you.
Start with Boots and Health Potions
AP Kogs, and just Kogs in general are able to take advantage of an opponents poor mobility early game due to his range. Buying boots will

Help you dodge Void Ooze
Keep him out of range

And in conclusion,
STEP ON HIS FACE MERCILESSLY
Because Kog has no real escape, except for Void Ooze which has been nerfed as I mentioned above. Just watch out for his passive, it's really useful for turning a death into a trade.
Comment: I'm sorry but Kog won't play aggressively early. Early, he doesn't have anough mana to be a threat. After level 6, with tear, kog can start playing aggressive but the range is not that long yet.
Answer: Leblanc is really good at blowing him up, but anyone who can do good burst damage against him and get away, or anyone that's good at closing the gap and getting on top of him, like akali.  But really there's a lot of different characters.  Kog is pretty weak early game so it helps to play semi aggressively to keep his farm down.
Answer: Fighting an AP kogmaw at mid early game is pretty much like fighting an Ashe early game.

Is squishy
Is only good at kiting

So, how do you fight a kiter?
You try to nuke him before he starts kiting.
Koggy's main strategy is to slow you, hit W and outrange you, effectively harassing you.
Staying too far away from him at level 6 isnt that safe, since his range is pretty damn insane (speaking of his ult). That said, the best way to counter such a champion is by getting in his face.
As soon as you get the chance, get in close and personal, CC, nuke and - if you are burst champion - retreat. If you are an AD based champion, keep bashing him. When fighting toe to toe, kogmaw's damage output disappears as soon as his W is off.
Tl;Dr
As AP burst champions: Wait for his W+E combo to end, get in close, nuke and retreat.
As ranged AD champions: Wait for his W+E combo to end, jump in and start bashing.
I know it's easier said than done, but trust me. It takes a while to get the hang of midding against various champions (3 weeks of anivia midding and i know how to fight Leblanc \o/ )
Comment: The main problem here is that a good Kog player won't let you get close and personal. You will end up being hit by a tower or ganked by a jungler.
Comment: Then one simply buys boots, stays out of range, dodges his ult and hopes he runs out of mana. If you cant attack him, farm and gank.
Answer: Personally I like to get luden's echo vs him to not only be able to nuke him more easily but also for the +10% movespeed it now gives.
Comment: That feels more like a comment than an answer.

What counters AP Kog'maw in mid?


Representing boolean function by a polynomial

Question: Supposing we have a boolean function from $f:\{0,1\}^n\rightarrow\{0,1\}$. It is clear that a real multivariate polynomial $p(x)$ such that $f(x)=p(x)$ on $x\in\{0,1\}^n$ can be multilinear. What are some interesting classes of boolean functions for which the minimal degree of $p(x)$ is known? Do we have concrete examples?
Comment: Related: http://cstheory.stackexchange.com/questions/25291/lower-bounds-for-polynomials-computing-the-boolean-functions
Comment: If you're not familiar with it, closely related is lots of work on "approximate degree", which asks, what is the minimal degree of a polynomial that "approximates" $f$? I don't know enough to give specific references but others would.
Answer: Any function which has non-zero correlation with parity has degree $n$. That is, if $$\sum_{x \in \{0,1\}^n} (-1)^{\sum_i x_i}f(x) \neq 0$$
then the unique multilinear expansion of $f$ contains the monomial $x_1\cdots x_n$. Indeed, since $(-1)^{x_i} = \frac{1-x_i}{2}$, the Fourier expansion of $f$ (expressed in terms of products of $\frac{1-x_i}{2}$) will contain the term $\prod_i \frac{1-x_i}{2}$, and the corresponding monomial $\prod_i x_i$ doesn't appear in any other term.
Nisan and Szegedy proved that functions of degree $d$ depend on at most $d2^d$ variables. For $d = 1$ we can be more exact: the function must depend on at most one coordinate.
Comment: You can take a look at Ryan O'Donnell's recent book, Analysis of Boolean functions.
Comment: This is an useful point. What is a good reference for this topic?
Answer: Classes of Boolean functions with unique multilinear presentation contain

Pseudo-Boolean functions over reals (Theorem 1.34 [1])
Boolean function over unit cube  $[0,1]^n$

Background

"Every Boolean function can be represented by a disjunctive normal form and by a conjuctive normal form." (Theorem 1.4 (p.16 [1])

so every disjunctive normal form (DNF) of the form $\vee (\wedge {x} \wedge \bar{x} )$ can be written as $\vee (\prod x \prod (1-x))$ and $\sum c \prod x$ and further definitions on the page 18 of the book such as subscripts. You can represent every Boolean function $F$ on $\mathcal B^n$ in terms of powerset $\mathcal P(N)$ and direct sum $\oplus$ such that $f(x_1,\ldots,x_n)=\oplus_{A\in\mathcal P(N)} c(A)\prod_{i\in A} x_i$ (THM1.33).
and their applications contain

Game theory on p.579 [1] with focus on multilinear polynomial extensions with the structure $[0,1]^n$
Reliability Boolean functions characterised in terms of minimum pathsets and different cuts, some information in p.58 [1], with the structure $[0,1]^n$
(circuits) Complexity of multi-linear polynomial computing Boolean function
(fourier analysis) Lower bounds for Polynomials computing the boolean functions

References
[1] Boolean Functions Theory, Algorithms, and Applications (Yves Crama, Peter L. Hammer, 2011)
Comment: Yes, obviously. Now, how does that answer the question?


What are the state and county taxes for refinancing a mortgage in Virginia?

Question: I'm in the process of refinancing a mortgage, and want to know what state and county taxes apply. I'm not talking about property tax here, but the recordation taxes and fees charged by the county and state when a mortgage is refinanced. In particular I'd like to know what the taxes and fees are in Fairfax County, Virginia, but I thought it might be useful to leave the question open so answers can be included for other counties in Virginia.
Comment: Unfortunately, a big list by county isn't as useful as one would think.  That information changes over time.  What would be useful (and I hope someone includes in their answer) is how to go about getting this information.
Comment: I agree, at least if the list doesn't include references so it can be updated at a later point. I just answered this question, at least in part, including references to the Virginia Code, which should not change very often. From what I've seen so far, at least for Fairfax County, is that there is no county-specific fee levied, in other words all taxes and fees are identical for every county. I'm sure there are exceptions to this, which I hope someone will find and post.
Answer: The county and state recordation taxes and fees in Virginia are mostly the same across the state, however I'm not sure if individual counties levy additional fees.
Refinancing with the same lender
If you refinance a mortgage in Virginia with the same lender, then you only have to pay recordation taxes on the difference between your original loan and the refinanced loan (Virginia Code § 58.1-803 D).
State recordation taxes
The Commonwealth of Virginia levies a tax of "25 cents on every $100" on the amount refinanced (Virginia Code § 58.1-803 A).
County recordation taxes
Counties in Virginia are allowed to collect "one-third of the amount of the state recordation tax", which would be 8.33 cents on every $100 (Virginia Code § 58.1-803 A).
Miscellaneous fees
The most significant fees come from the county and state recordation taxes, but there are some other miscellaneous fees. These include a clerk's fee of between $21 to $55, plus $20 per oversized plat sheet, and a $1.00 "Open Space Preservation Fee".
These taxes and fees are all nicely summarized in a PDF produced by Fairfax County.


Handling Missing values in stocks returns when estimating the co variance matrix

Question: What is the best way to handle missing values when stocks did not exist for the entire historical period?.
Answer: One really nice book that comes to my mind is

Little, Rubin, Statistical Analysis with Missing Data

I read part of it but probably it is too much information in your case.
For your application, i think you can categorize the problem into two possible subproblems:
First, time series that have unequal starting points (when some stocks' history is shorter):

Page, S., 2013, How to Combine Long and Short Return Histories Efficiently, Financial Analysts Journal 69, 45-52

Second, data that misses in between the time series (for example on public holidays):
Well, there is the EM algorithm. Take a look at it. The most cited paper here is

Dempster, A. P., M. N. Laird, and D. B. Rubin, 1977, Maximum likelihood from incomplete data via the EM algorithm, Journal of the Royal Statistical Society 39, 1-22
  It is an iterative, two-step algorithm.

You can also find the concrete formulas in Meucci(2005) "Risk and Asset Allocation". On his (Meucci's) webpage you can find the corresponding matlab code.
Comment: thanks, I will look into it. The reason for the question was to do perform a backtest portfolio strategy(min var,erc etc) on maybe the all share index but some stocks in the index may not have the full historical time series if one assumes a particular starting date for portfolio construction. I mean in order to estimate the covariance matrix, so I am not sure if I would incur some form of bias if one deletes stock that do not have full history to estimate the covariance matrix.
Comment: @user3481555 Well if you delete the stock you simply reduce your investment universe. My intuition says that this induces at least some bias because the stocks with shorter history had a reason to enter the index later on. On the other hand, If you throw away the all the data where at least one stock has a missing value you might run into dimension problems (if you estimate a covariance matrix for hundrets of assets you want to search for "dimension reduction" or "shrinkage" or "robust" in quant.SEs search function). I will see if I can come up with the paper I mentioned...
Comment: well yes I intend using Ledoit-Wolf Shrinkage Variance Estimate. I dont know if you are familiar with R, I found a package in R(BurStFin) function is var.shrink.eqcor that returns a variance matrix that shrinks towards the equal correlation matrix. It works with missing values.
Answer: @vanguard2k and @Theja provide useful information. In my experience, unequal starting points is most common, so I'll try to focus on that.
The technique that @vanguard2k mentioned for unequal starting points can be thought of like a regression. You start with the longest available data and get the covariance matrix of that. For the next set of available data, you regress them against the data that is available longer and use the regression coefficients to expand the covariance matrix (and means). You then iterate through each unique group of data, steadily shrinking the amount of data used in each regression.
The above approach can be considered more general than simply just for estimating means and covariances. If every step is a regression, then you can make any assumptions you want so long as it fits within the context of a regression (for instance, you could estimate a garch model for S&P 500, then regress Facebook against S&P 500 with some garch process as well for the residual variance). You may not be able to get an analytic formula for the covariance, but you can simulate from the model and calculate the simulated covariance matrix from that.
As an alternative, multiple imputation would be like if after the regression you use that model to simulate some missing data points. In the next step, instead of using only the available data, you use the available and the simulated missing. You then re-do the above steps many times (where the multiple comes from) until the parameters settle down. I find it can be helpful to learn about multiple imputation before trying to learn about Gibbs sampling.
The EM algorithm is also very similar to multiple imputation, with the exception that EM is filling in the missing data with the predicted value whereas multiple imputation is filling in with simulations.
Regardless, you may run into difficulties when the number of stocks you're looking at expands to more than the number of time periods (like any covariance estimation, really). One way to resolve this can be to apply PCA to each of the subsets of data, as appropriate. Alternately, you can limit the regression to something like the country/sector/industry indices. Either of these approaches is like making some assumption that certain correlations are zero.
Things become more complicated when you start dealing with data that easily be assumed to be I(0). For instance, suppose you want to estimate a VAR model for the S&P 500 (in log levels), S&P 500 E/P, 10 year U.S. Treasury yields, inflation, and VIX. You want a VAR model in this case because there might be some mean-reversion or cointegrating relationships. You will likely have data over the longest period for S&P 500, but less data for inflation, yields, E/P, and VIX. Since the data is not iid multivariate normal, you can no longer use the techniques mentioned by @vanguard2k. The difficulty is that when you simulate data, it needs to depend on both today's value and however many forward or backward lags are needed. There's a Gibbs sampling approach that can deal with this type of situation (Bayesian Mixed Frequency), but it's rather sophisticated.
Answer: A simpler question would be the following: suppose you want to find the covaraince between the returns of two stocks and each of their time series has missing values at different places. What is the best way to compute covariance here? One very sensible way to approach this is to throw away the observations where ony one of the stocks has a return value. Of course, you are throwing away observations in this approach. But, using any other approach may introduce bias in the later steps of your workflow that may be undesirable (unless you introduce a knowledge based bias to specifically compensate for the lack of observations).
Also, check out some of the questions on Cross Validated related to imputation and missing values (for instance, the first answer for this question).


Why don't cameras have autofocus points in the edges and corners?

Question: On all the DSLRs I've used, there are never any autofocus points near the edges and corners. Why is that?
Comment: @FredP no - it's an physical limitation, not an arbitrary decision by manufacturers
Comment: Probably because camera makers consider it less useful (and it would be more costly) - although for instance Nikon's D300 has a rather large coverage. But I agree that sometimes I would have enjoyed using that possibility instead of having to "deframe", focus and reframe.
Answer: Phase detect autofocus in DSLRs works by comparing patterns of light coming from each side of the lens using pairs of detectors which are separated a certain distance on the AF sensor. This distance is called the baseline, and the greater the baseline the more accurately the distance can be measured.
The need for a wide baseline and for light to travel from either side of the lens makes it impossible to have autofocus points at the very edge of the frame. The further out you go from the centre the shorter the baseline which is why the outer focus points are often less reliable.
APS-C DSLRs appear to have AF points which cover more of the frame, in reality the positions are similar to a full frame DSLR but the frame itself is smaller.
Comment: That said, you can have sensors *near* the edges that lose their effectiveness with diminishing light and smaller apertures, or *at* the edges *if the imaging sensor is small enough in comparison to the AF sensor and lens image circle* (such as, say, using a Nikon D4 in DX/crop mode). It's just a matter of being willing to pay for what you ask for.
Answer: Because autofocus needs a considerable amount of light, and the lens construction gives more light getting closer to the center. Also, lenses tend to be sharper the closer you get to the center. That is why using the middle focus point and then recomposing usually gives the sharpest result.
Comment: -1 It's neither of those reasons
Comment: It's not true that autofocus needs a considerable amount of light, the 6D AF is rated to work down to -3 EV, which is the equivalent of a 60 second exposure at f/2.8 and ISO100! You do get vignetting toward the corners but not enough to stop AF working. The being able to focus on very fine detail would be compromised by a lack of sharpness in the corners, but in principle the ability to measures phase differences with coarse features is largely unaffected by lens softness.
Comment: @MattGrum: these are contributing factors, believe it or not.
Comment: Interesting! I will study this further.
Answer: Are you sure you'd even really want ones on the perimeter?  For me, I turn off all of the auto focus squares except the middle one. Why?  If I'm shooting through a tree, for example, I want to focus on my subject which may be 30 feet away. I don't want the camera to focus on a branch (off center) that is 8 feet away.  I would never want focusing sensor squares around the perimeter of my lens.  But that perhaps is just me.
Comment: Welcome to Photography on Stack Exchange.  As currently stated, this answer only indirectly answers the question.  You have expressed why you don't think it is necessary, but it doesn't answer why they wouldn't bother for the rare case that someone might want to focus on something on the edge of the frame.


Is it worth learning the SVG path attribute, or should I use a tool for drawing?

Question: Is there an advantage of manually creating the graphic with the path element and d attribute (I guess with the help of math?), over using a tool like Inkscape to draw the graphic? Does Inkscape generate more inefficient SVG code?
Answer: Well, there are two schools here....

Ask a print designer if he/she can write postscript code and they'll laugh at you. Print designers have never been interested in learning how to manually code a postscript file for output. They rely entirely on WYSIWYG editors (Photoshop, Indesign, Illustrator, et. all). So the answer would be an emphatic no.
Ask a web designer if he/she can write markup or code to create a web site and you'll generally here a "yes". Most WYSIWYG web editors aren't as proficient as a human. Sure they can be faster, but they aren't always as thorough or detailed in some areas. So many well-versed web designers/developers prefer to manually create markup/code. So ask this group and you'll get a general yes.

Now, whether or not directly writing svg code is valuable to you is another matter. I, personally don't give a hoot how the SVG code is written provided it displays as I expect. I also know that I can use a WYSIWYG editor, then manually open the svg on a text editor to "tweak" if needed. So I don't know, and don't care to know, all the ins and outs of svg code. I learn as I need to.

A benefit to writing your own svg would be control. Writing manually you can often be far more detailed and structured than any automatic method ever is. See the web bullet above. If you are the meticulous type, you may find a great deal of satisfaction being able to construct svg graphics from a text editor.
A deterrent would be time. It is often much faster to use a WYSIWYG editor. Or use the editor then go in and manually alter the svg code.

So it's really your call.
As for benefits to others (employers/clients, etc) that's hard to say and would depend a great deal on your proficiency and speed. If you can create a manually written svg graphic in the same time it takes to open Illustrator/inkscape draw and save, then it may be valuable to some third party. However, if it takes you two or three times longer to write the code, well, I don't know anyone that wants the same thing at twice the price.
Comment: Interesting point of view. A third way is the way of the *developer*: SVG is a valuable kind of output for applications because is accurate and simple to generate (and the answer would be an obvious **yes**).
Comment: @PaoloGibellini yeah that was kind of what I was alluding to in the "web" bullet. If you *want* absolute control, there's certainly no better method - just like with markup.
Comment: I agree, but could be interesting even the distinction between the web developer, who uses SVG in a specific context (as images in the web page) and the developer, who uses SVG as output of an elaboration software (as diagram or as element to be put into a report or a research).
Answer: SVG isnt terribly hard to write by hand. Its a bit overly verbose for my personal taste, but thats besides the point.
Depends on what yo do
There are several reasons to know how to write a vector file manually.

You have access to some data, and you need to be able to open it in a graphics editor. Dumping the data into SVG, EPS or DWG is relatively easy. You can then process it further in any application.
This can make you incredibly many times more productive in some instances. But you can never attain productivity if you never bother to learn the format. If your a programmer you definitely should learn for this reason.
Example question and usecase: import-vector-data-into-illustrator
Your doing something your editor does not do well. There are still things that are easier to do in nongraphics editors. Most notably mathematical typesetting, but sometimes other things like custom halftone generation etc etc.
One big SVG usecase here is generation of CSS for some interactive use. Or preparation of svg animation. But its not limitted to this only. In many cases a for loop or a simple find and replace, or a few text copypastes can do wonders that would be extremely tedious to do by hand. Being able to compose nested transforms can be used for fractal generation in a way that would be a nightmare in your GUI.

But if you know how to do this then all sorts of weird reasons crop up. Such as:

You need to draw a picture but all you have is a terminal. Besides your descring how a sequence happens so being able to read what I did is a bonus. Example of this kind can be found Here

In General
For most users it is not meaningfull to learn. So no. But it does not hurt to know this so you might spend a few weeks on the subject if you find it interesting. It might pay off bigtime.
Admitteely the need does not raise very often even for me.
Comment: While valid, your first point is not exactly what I would call "manually". The important distinction to make here is between generating paths manually and having the knowledge that would be required to generate paths manually. The latter is what is important.
Comment: In order to do something automatic you need to do it manually up to some point @Wrzlprmft. So you would probably do 10% manually and then wrap the rest in a loop. Doing manually is the sketching of automatic. And note the user is asking learning how to do it you begin manually in all cases.
Comment: Not necessarily. I automatically twiddled with Bézier curves a lot, but I never programmed one entirely manually. For my numerics course, I once programmed a Bézier renderer, but when tasked to test it with some data, I got it from Inkscape straight away.
Comment: Sure, bit different usecase, but you dont exactly need to go that deep in svg. You still need to populate the points its comparable to search and replace so not really manual even when using a text editor. So in many cases automatic might mean doing search and replace on your data dump.
Comment: What im getting at is that there is not much that is entirely manual on a computer. YMMV, as far as im concerned everything is the same.
Answer: To answer your literal questions:

Is there an advantage of manually creating the graphic with the path element and d attribute (I guess with the help of math?), over using a tool like Inkscape to draw the graphic?

Very rarely. I usually never use WYSIWYG tools, but for designing graphics, I do. Furthermore, you can tweak node positions and similar manually from Inkscape's interface if you want to.
However, knowing how you would generate paths manually can be very valuable:

Knowing what happens under the hood helps you to better understand what you do when using WYSIWYG tools. There is a strong relation to: Is math needed for graphic design?. For an example that is directly about the mathematics underlying curves, I would like to refer to this answer of mine.
If you knowing how you would generate paths manually, you also know how you would manipulate SVGs automatically, i.e., with a program. Joojaa's answer already gave some good example for this.

Does Inkscape generate more inefficient SVG code?

Yes. Inkscape's code is not aimed at being small. There are specific tools to reduce your SVG's file size, but they can only go so far, because they do not know what is important. If you need to go further for some reason, you have to manually "golf" your SVG, see this answer for an example. Still, if you do this, you will usually start with a WYSIWYG-generated SVG and not from scratch.
Answer: The answer is both. That is why both options exist.
I don't mean that some graphics are made in a drawing app and some made with code, I mean that with every graphic you create, you have these tools ready:

pen
vector drawing tool
UTF-8 code editor

… because that is the SVG toolkit. And generally speaking, you use them in that order.
For each graphic you create, you might use 99% drawing and 1% code, or 10% drawing and 90% code, or 50:50. But if you want to make the best graphic you can make, it is highly unlikely that you will use just drawing or just code.
The code part may just be optimization, or it may be animation, or it may be taking a simple graphic and creating a complex one with rotations, or it may just be checking to make sure you didn't accidentally create an SVG that just has an embedded bitmap in it. But ultimately, you are creating and publishing code, so you want to at least sign off on what you are shipping.
And on the other hand, if you want to make an interesting graphic that has some art in it, some life to it, you will gain a lot by using your eyes and visual cortex to at least create a first draft of your final graphic. You may want to import clipart as a starting point, or use previously made graphics as templates. These and other tried-and-true vector graphics production methods don't get thrown out the window because SVG is stored as a text-editable XML Web document. The XML document is an added feature for vector graphics production, not a replacement for drawing.
In short: use the whole toolkit. Don't tie one of your hands behind your back.
Comment: Well actually not really, maybe, or not quite. The reason you have human readable formats is because it makes debugging and programming easier. It was never originally meant for them to replace software. But over the ages the formats started to live a life of their own and became something that the software's couldn't match up with. They became too flexible for GUIs and turned into sort of descriptions that could be used too broadly for the GUI side to keep up. So markup was meant to be good fore the original developers but in the end they surpassed their original purpose.
Answer: Here is a page with a bunch of tutorials in SVG, one of them about Paths.
I used it to draw a lot of circles with the help of a program, and to my surprise, there is a core circle definition in SVG which is much more simple, than what Inkscape produces when I draw them by hand.
But Inkscape was fine in reading that format and drew what I expected. Just on saving the file it added its own boilerplate.
So I would recommend to learn from such tutorials and not (just) from the SVG inspector view inkscape offers.
Answer: As you are asking in the Graphic design forum, the answer is no.
If you were asking on stackoverflow.com yes.
Comment: Although I think that's the answer you would get if you asked those two communities what they themselves do/would do - I don't think that is the answer to the question.


Why is my Microsoft Pinyin IME suddenly making traditional characters instead of simplified?

Question: I tried to type 什么, but I got 什麽! It was working just a minute ago.  What happened?
Answer: The Simplified Chinese Microsoft Pinyin IME is capable of both simplified and traditional characters. When you install it, it will be set for simplified characters. It is set up to toggle between simplified and traditional with the keybinding ctrlshiftF. It is easy to do this accidentally if the IME is active and you do a "Find All" in Visual Studio or a similar program with the same keybinding.
You can toggle back by activating the IME (if necessary, using WinSpace) and then toggling back with ctrlshiftF.
You can disable this key or change it to another letter (note, ctrlshift is not optional!) by navigating to the keyboard options:

Press WinS and start typing "language" and select:

Click on the language and it will expand and offer an "options" button:

Now find the keyboards, click on the "Microsoft Pinyin" keyboard (probably the only one):

From there you can toggle back to simplified under "General" and modify the toggle binding at the bottom of "Keys"
Answer: Under General Pinyin style, the character set could be been set to Traditional chinese.
Switch to Simplified chinese from there.
Answer: I know this has been answered before but as of 08/12/2020, the simplified language pack can be switched to traditional either intentionally or not by pressing ctrl+shift+f and to stop your computer from doing this just do the following
Go to Language settings and click Options

and then click Microsoft Pinyin's Options button

Go to Keys

and then at the bottom you can disable this setting

This gave me a lot of headache as I needed to use simplified for my job.


Do you have a GPS signal on board a plane?

Question: Does anybody know if there is a GPS signal available on board a plane with a common and normal GPS receiver?
Comment: Also see [Turning off GPS on a flight](http://travel.stackexchange.com/q/1949/108)
Answer: Unfortunately the plane body does an excellent job of blocking GPS signal.  In general if you're in a window seat you will be able to get a signal by holding the GPS near the window (or, for example, on a tray table) - but if you're elsewhere on the plane it's very unlikely you'll get a signal.
The exception to this may be the new Boeing 787, which is made primarily of Carbon-fiber reinforced polymer (CFRP). Not only does CFRP allow for larger windows (which would allow a greater visibility of the sky, and thus more GPS satellites), but it's likely that the GPS signal would pass through the aircraft shell better than on conventional planes.
Keep in mind that not all airlines allow passengers to use GPS receivers in flight (they are technically "radio receivers" which are often not allowed).  Be sure to check with the specific airline and/or the flight crew to confirm that you are allowed use one.
Comment: I've seen my GPS report a speed of 1258km/hour when travelling with a ~300km/hour tailwind. The "airshow" display on the plane showed a speed 2 km/hour different, so the GPS was obviously extremely accurate even at that speed.  (Yes, that's technically faster than the speed of sound - but due to the tailwind we were not technically going faster than sound relative to the air around us)
Comment: Munitions restrictions in the US mean most consumer GPS would fail to operate if both alt>18000m and speed>515m/s.  You shouldn't be near either limit in commercial aircraft.  Hiking units use the same chipset as others and wouldn't be expected to have any problems at airline speeds.
Comment: @RicardoGiaviti: planes internal systems also use GPS. So do some missiles guidance systems. And these fly way faster than any plane.
Comment: But see [this answer](http://travel.stackexchange.com/a/46603/19400) reporting that the 787 had the *worst* GPS experience.
Comment: Do you know if the speed of the plane can disrupt the GPS receiver?
Comment: @vartec true, but they may well have higher speed processors and different sampling rates, enabling them to better handle those speeds. I could imagine a GPS system for hikers to get a bit confused when having to handle Mach range speeds, it may not even be able to display them.
Comment: Even when the receiver is stationary, the distance to a GPS satellite can easily change by several kilometer per second -- planes are slow compared to that.
Comment: That's why my (4 year old!) answer said it "may" be an exception. Based on multiple reports since, it seems it's actually worse as you've said.
Comment: I had the opposite experience on a B787. Up against the window, I had no GPS signal and no cellular signal. My experience in all other planes is that I can get both signals at the window.
Comment: The plane's speed _does_ affect the receiver, esp. the time to initial fix. All GPS use a "sanity check" on their first few results. In a handheld GPS those are not expected to be much farther apart than can reasonably be covered by a ground vehicle in the elapsed time. If you're already at a few hundred kph this check will fail and the GPS will take longer, sometimes much longer, to realize "oh, you really are moving that fast" and settle on the initial fix. The GPS units installed in airplanes of course don't have this issue.
Comment: *"Keep in mind that not all airlines allow passengers to use GPS receivers in flight"* - which is ridiculous, because a GPS receiver is a completely passive system. But an average flight attendant might not have the technical knowledge to be aware of that.
Answer: Yes, but the signal can be a bit weak. It's best to hold it to the window to get a lock. Depending on the GPS device, some are able to "hold onto the lock" even if they are not facing the window, so you only need to have it by the window for the initial lock. You may or may not be allowed to have it in the GPS.
Here's my GPS while I was travelling near the equator. Look how I'm 4,500 m above sea level and travelling at 600 km/hr.

crimey was that 4 years ago... where does the time go...
Comment: Crimey? I assume crikey or blimey?
Answer: I am a (private) pilot, and have used my various GPS enabled devices for years both when I fly myself, as well as on commercial flights. (In the past, when they were not allowed, I applied for and obtained special permission from the airlines I was then flying.)
Depending on the seat location, and position of the GPS satelite constellation, my reception varies from mediocre to excellent.  With a newer iPad, possibly containing a better chip or antenna, my capture rate for good position is generally over 90%, with the proviso that a window seat be selected.
Aircraft type seemed unimportant - until my most recent commercial flight.  On the outbound leg, over 10 hours on a B777, I enjoyed superb capture and positional accuracy.  The return leg was on a B787, and over the more than 10 hours of flight time I received not a single fix, even with the iPad up against the (large) window. Indeed, I wonder if the 787 has some kind of GPS jammer in the cabin, since the GPS signal actually occasionally showed 1 meter accuracy, but without an actual location, and then immediately dropped to "No Fix" - so it seemed that an extraneous signal might have been present.
BTW it is worth noting that a number of highly experienced pilots have recently landed at incorrect airports, with several such events well publicized.  An iPad in the cockpit, running one of the readily available aviation programs, would have avoided such embarassing - and potentially dangerous - events.
Comment: Wait, are you claiming that iPad GPS and apps are better than what is installed by default in the airplanes...? That sounds scary
Comment: I've typically had functional GPS tracking our path when the device is in or near a window, provided I get the initial fix before we start moving.  But even then, it frequently has large gaps of location unknown.
Answer: Yes, I did have GPS reception on my cellphone during a flight. However, it took quite a long time to get the initial coordinates, and I could not get updates on my location very often (the coordinates changed maybe once every 3-5 minutes). So I would say you would have bad reception in the best case.
Maybe dedicated GPS devices would have a better antenna & reception than my $300 phone.
Answer: I have flown (as a pilot as well as a passenger) with a variety of GPS units (hand-held Garmins, iPhones, iPads), in a variety of aircraft, from my own single engine plane up to the largest commercial, with the portable GPS unit providing excellent position, speed and altitude information.  Indeed, my iPad correlates superbly with my Garmin GNS 530, and serves as a backup for the (certified) Garmin unit.
Several mis-statements are common:

an iPad and iPhone can (and most do) contain a 'real' GPS unit.  Some information can be obtained by triangulating cell phone towers, but cell reception can be turned off, or the unit can be in the middle of a cell-free zone (such as an ocean) and GPS service continues.
an iPad of iPhone, with the cell system configured to 'off', will not interfere with aviation electronics.  In that configuration, the unit is in 'receiver mode' only.  However, please do turn the cell phone portion of the unit off!
The fuselage of most commercial aircraft will allow sufficient penetration of the satellite-transmitted GPS signal to permit excellent accuracy.  I have flown extensively while receiving good signals - in a large variety of aircraft, including regional jets, B737, B757, B777, MD80 etc etc.
I have only flown in a B787 twice - and in NEITHER CASE WAS I ABLE TO RECEIVE A USABLE GPS SIGNAL. I had a window seat both times, each flight was in excess of 10 hours, and at no point did I receive even a marginally usable signal.  I presume the fuselage of the B787 contains denser EM shielding than the typical aluminum skinned airplane - probably related to lightning protection requirements for the nonmetallic structure.
Comment: @Vince New users may not be familiar with the editor. The best thing to do in these circumstances is to simply fix the formatting of the post, and perhaps point them to the [online help](http://travel.stackexchange.com/help/formatting) for same.
Comment: Hello, welcome. Do you need to shout? Also, I don't think you need to mention cellular receiver, while it is used on earth for positioning, it seems clear for this question that it is off-topic.
Comment: I concur with your observation on the Boeing 787. Not only was it impossible to receive GPS right up against the window, I could not even receive cellular signal inside the plane at an airport. In other airplanes, my phone works just fine.
Answer: I tested this once on a flight which claimed it was fine, once you'd taken off, and not during landing - to use devices like this.
I have an app on my phone (MyTracks) which is meant to track you when running, for example, but I just turned it on and left the phone running in my pocket. Not ideal for GPS, but I was in a window seat, giving it a slight chance.
Long story short, there were some data points recorded during the flight, and at a range of altitudes. It wasn't a steady connection, but it was certainly received intermittently, until the final 'please turn off all electronic devices' warning came and I had to stop the test.
Answer: I have a Garmin Oregon 550 and I can confirm that one can get a decent signal if the reciever is positioned close to a window. Getting the initial fix might take a few minutes, however. For all the flights where I did not have a window seat, I lost the signal sooner or later and never got a fix again.
My experience is, that different airplanes actually do make a difference. I remember having excellent signal in a Boeing 747 Jumbo, while in Airbus A340 the GPS reciever would have to be close to the window all the time to prevent it from loosing the signal. I can also confirm from a recent flight that in the Boeing 787 Dreamliner there is absolutely no signal at all, not even close to the doors or emergency exit. I didn't expect this at all due to the plane being made of carbon fibre which normally transmits the GPS signal. I figure that at least the windows are (electrochromic) smart glass windows and they therfore don't transmit any GPS signal. So holding the GPS device close to the windows doesn't help in a 787.
Answer: I just used my Android phone GPS app to clock the plane's touchdown speed yesterday. The plane was an Airbus A320 , I was seated at the window. The plane's touchdown speed was about 250km/h. It was not easy to clock the speed at landing using an android app because the pilot seemed to apply brake at the same moment of touchdown causing a steep velocity change within subsecond interval. The Android app GPS status refreshes only once per second. But, tracking the flight's location was very accurate. I saw the shore line of Detroit dotted with 2-3 nuclear plant cooling towers, and surely enough the Google map pointed my location at the Lake Huron shore.
Answer: The best GPS performance I ever got on a plane was on an iPhone 5s, by:

getting a window seat on the side that will face the equator during the flight
getting a good starting fix before the plane starts moving
putting the phone flat against the window and pulling the shade down to hold it there.

My Garmin eTrex-30 claims to get 3-5 meter accuracy when held against the window, but drops to ten meters in my lap (and frequently claims to have lost signal).  Also, I don't trust its accuracy claims because once out in the open, it mapped two fixes twelve meters apart when both were actually taken at the same spot and it claimed four meter accuracy.
Comment: It's true that the satellites are not in geosync orbits; they follow the usual "apparent sine wave" pattern, but that pattern does "cycle" back and forth with the equator in the middle. So if you look at the "satellite map" that most GPS receivers and apps can display you'll find more of them closer to the equator than farther away. My experience using GPS aboard commercial a/c (mostly with Garmin GPS V, then later, bluetooth receivers with SirfSTAR III chipset) has invariably been that my receiver can "see" far more sats from an equator-facing window than from the other side of the cabin.
Comment: It'd be interesting to see whether you could get the same performance on a north-facing window.  It shouldn't really matter, since [GPS satellites are not in equatorial orbits](http://www.gps.gov/systems/gps/space/) like, say, satellites carrying TV signals.
Comment: Ohs, I thought they were geosynchronous.
Comment: Re my prev cmt - Since your airplane may be south of the equator I suggest that "a window facing toward the equator" is a more generally useful phrasing than "facing south". Edited answer accordingly.
Answer: As others have already said, it works in most airplanes, but in the dreamliner specifically (787), it will not work due to the fancy windows that can dim themselves but also contain a conductive material that prevents the GPS signals from getting in. It's not GPS jamming, but just unfortunate GPS shielding.
Source: I use my Garmin GPSes in all airplanes I've taken, they've always worked next to the window, except in all dreamliners I've flown in.
Answer: Seems like recent phone GPS chips work pretty well to give you some rough estimate. I'm able to reliably get GPS fix when holding the phone next to the window (Samsung S9). You can see some pictures I took in the past (GPSTest app).
The pictures were taken 9 seconds apart. There is a discrepancy between board computer speed reading and GPS speed reading of like 100kmph. Or maybe I didn't wait long enough for a better fix.
Still I often found it useful to see where am I at the moment, whether plane is descending already, etc.
Answer: Used galaxy A5 with google map and FLIGHT MAP free inside A320 NEO and Boeing 737-800 with excellent Gps fix (on window seat)for a complete 3 hour flight without any problem.Just turn on gps asap once inside plane or do it even before before bording the aircraft and put phone on flight mode.


Manchester, UK Airport time to get through security

Question: I am flying from Manchester to Heathrow to Brussels.  How long will it take me to get from the train station in the Manchester Airport to the British Airways gate - I am US Citizen and assume I will not need to go through customs but will need to go through security.  This will be a Monday afternoon 3:00 flight.  What time must I arrive at the airport train station to make my flight?
Answer: I can't comment on how long check-in/security would take, but depending on luggage, it's at least ten minutes from the station platform to the departures lounge in the terminal, and quite possibly 20 minutes.
Manchester Airport has a single, central rail station connected by long passageways with moving walkways to the terminals, so it's roughly comparable to changing terminal at most airports.
Answer: Standard guidelines state that for European flights you should aim to check-in two hours prior to departure. Whereas for domestic flights the Manchester airport suggests one hour.  I think something in between is a good tentative plan, especially if you have luggage to check-in.
Regarding the transfer time from the train station to the British Airways gate, it's hard to be exact since security checks can take an arbitrary amount of time, depending on how busy they are. Nevertheless, let's try an educated guesstimate.
For the station to airport transfer, I ran a quick search using this nifty tool by inserting the information you provided. According to the information I got:

Train
The Station is a 10 minute walk from Terminal 1 and 15 minutes from Terminal 2 using our Skylink moving walkways. It takes about 5 minutes to walk from Terminal 1 to Terminal 3.

Considering this, plus the two-hour guideline, I would say that you should aim to get to MAN airport train station two-and-a-half hours before your flight, i.e. at 12:30 at the latest.
You could reduce this safety margin by checking-in online, which will should allow you to avoid the check-in queue and go directly to the luggage drop-off point. Note however that the queue-jumping advantage is airport-dependent. I.e. I don't know if at Manchester Airport BA provides different lanes for people who just have to drop their luggage off.
In case you don't have to check-in your luggage you could reduce the two-and-a-half hour margin even more. Of course these techniques are risky and could cost you your flight. Personally I am one of those people who prefer to be safe rather than sorry.
Answer: The reference point is check in 14:15 to allow the minimum 45 minutes interval between check-in and flight ETD:

Assuming you check-in on line, bag drop off, Security, transfer to gate etc is covered within that ¾hr. Once in the system just going with the flow should be sufficient.
I expect departure from T3 (worst case anyway, as it happens), so 15 minutes from train station:

hence need to be at train station by 14:00. Allow a margin (I suggest 30 minutes) for the sort of things that quite often don't go wholly according to plan and that requires arriving by train by 13:30 at the latest.
It gives at least 1/2hr contingency over 1-1/2hrs, or 50% more than required were everything to go smoothly. And then add to that any extra safety margin from arriving a little before 13:30 because that is the last train scheduled to do so before then.
The slack is as much for peace of mind en route as of necessity. Anything goes badly wrong and two or three times as much slack might not be enough anyway. The chances of every possible little thing going wrong to add a few minutes here and a few minutes there at every stage, and sum to a significant total, are negligible.
I'd certainly allow more margin if say the trip to Heathrow was to catch an onward international flight (specially if on a non-flex ticket!) But it seems the downside is nowhere near as bad as it might be (eg visa expiring that day). BA may have two later flights the same day to choose from (17:20 and 19:00) and even a single ticket is not cripplingly expensive (under £200). Plus there are trains, or even a taxi (about £230 - but about two hours longer than by air).
The trade-off is very roughly: waste an hour or so on every such journey to be reasonably sure even the worst plausible eventuality will not throw you off course – or save 12 hours over a dozen
 such journeys in the expectation that one of those may well end up costing about £200 more than the others and take two hours longer. In other words, is an hour of your time worth £20 to you?
If yes: Get to the train station by 13:30
If no: Get there about 12:30


Which chinese martial art is known in the West as kung fu?

Question: Since "kung fu" is not a martial art and simply means the mastery of a discipline, I'm wondering firstly which martial art is known in the public eye as kung fu and secondly which martial art is actually taught under this name.
Comment: "Kung Fu" can be translated as "martial art" - so all of them are.
Answer: The Chinese term "Kung fu" (gong fu) usually refers to martial arts, though it also more generally means skill attained through hard work that can be applied to any skilled trade. When referring to martial arts, the term does not refer to a single martial art but can refer to many different martial arts styles.
Chinese martial arts tend to be less organized than their Korean (tae kwon do), Japanese (karate, judo, aikido), and Western (boxing, fencing, wrestling) counterparts. Organization means there is a governing body that makes decisions. Without organization, variation is very high.
The term kung fu is applied to styles including, but not limited to:

shuai jiao
wing chun
hung gar
shaolin
mantis
white crane
baji
bagua
taiji
xing yi

Many of these styles themselves can be subdivided into distinct substyles.
I personally would consider the application of "kung fu" to styles such as karate to be correct when considering martial skill earned through hard work, as opposed to classification of martial arts. Karate is not normally referred to as kung fu because it is named from Okinawan or Japanese origins, which use different terminology.
Comment: Kung fu does not specifically refer to martial arts, though that connotation is very strong in popular culture. A classic non-martial use of the term refers to the [traditional tea ceremony](https://en.wikipedia.org/wiki/Gongfu_tea_ceremony), and masters of calligraphy have long been described as having good kung fu. I otherwise agree with you on its general use to describe martial arts.
Comment: So it depends on the movie actor or teacher. It's like joining a club called "Japanese martial art" and not knowing if you're going to be taught karate, judo or aikido - weird.
Comment: @WaterBearer - the kung fu gyms in my area generally specify their respective styles somewhere in their name. "Wing Chun Kung Fu Academy" and so on. Those that don't usually list the names of the styles that are taught on their website/front door. As gym space is expensive in metropolitan areas, it's not unusual for different teachers to group up and share a gym, so the name on the door can be a little bit more generic (but they'll still list all the styles somewhere).
Comment: @Dungarth I think we are actually in perfect agreement, though my wording should have been better. See if the new edited wording is better.
Comment: @WaterBearer It's like joining a club that says karate, but not knowing whether it's a Goju-Ryu, Uechi-Ryu, Shotokan, Kyokushin, or actually a Tae Kwon Do club that uses the word karate because people know the word from the movie "The Karate Kid" but not TKD [I have seen such a place]. Most people cannot tell the difference between any of these martial arts; "kung fu" is the appropriate level of detail for this audience.
Answer: Technically the Chinese term "Kungfu" (spelled and pronounced numerous ways) means "skill obtained through hard work and diligent study" as stated in the previous post.
However, if you use this term in China it will be always be assumed that you are speaking of "Chinese Martial Arts" and nothing else.
There are other terms in the language that are used too. These often have specific connotations in mind: "Wushu" - for the performance side of martial arts, "Sanshou" - free fighting (no weapons used), "Kuo Shu" - a general term for combative martial arts (not necessarily respectable or earned through hard work and study), etc.
Though you could technically make a case for using the term "Kungfu" when referring to a martial art of any origin, that might appear dishonest frankly. Kind of like calling a person an "Engineer" when what they really do is collect garbage from the streets ("Sanitary Engineer").
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Answer: There was a movement in the mid-20th Century to use the term Wushu (武术 "War Arts") as an umbrella term for the entire body of Chinese martial arts.
This included work to create standardized forms with an emphasis on promoting the sport. (Standardized forms are easier to judge for a variety of reasons, although most tournaments also have events for traditional forms.)

Where "Kung Fu" was a euphemism applied to any and all Chinese Martial arts in the West, Wushu is today generally acknowledged as the formal term.

Here are the entries from the Oxford English Dictionary on early English usages:

1966   Punch 14 Sept. 388/3   Kung-fu is here.
1968   Clarendonian XXII. 270   Chinese Kung-fu is still taught
today—but only as a Martial Art to a very select, carefully chosen
few.
1970   K. Platt Pushbutton Butterfly i. 9   The Chinese now call their
form of karate Kung Fu... It's mostly leg-fighting.
1971   'A. Hall' Warsaw Document xvii. 213   It was probably kaminari,
a bastardized form of kung fu.
1974   Listener 17 Jan. 93/3   The plot..hinges on Lee wiping out an
ex-monk, Kung-fu (martial arts) vice chief.
1974   Bookseller 13 Apr. 1961/1   There has been a great upsurge of
popular interest recently in kung fu, the ancient Chinese art of
self-defence, encouraged by the films of Bruce Lee..and the television
series Kung Fu.

It's not unlikely that Bruce Lee himself was the original driver of this term, in that he was famously teaching in the Bay Area right around the time the term started popping up. (This makes sense as Master Lee was a Hong Kong resident, as opposed to the mainland, such that there may have been numerous reasons for his use of an alternative term to Wushu.)

Lee was also surely using the term per it's actual Chinese meaning, well translated as "skill obtained through hard work and diligent study", as opposed to referring to a specific martial arts style in that he was developing Jeet Kune Do at this time, based on the idea that true combat can have no limitations, and not be bound by adherence to a particular style or system.
Comment: Why a euphemism?
Comment: @mattm Euphemism b/c "kung fu" used as a label for Chinese martial arts is not literal, compared, for instance to Wushu.  Bruce Lee notably used both "Kung Fu" and "Chinese Boxing", and my sense is he used the latter term to refer specifically to the Chinese system of martial arts in all of its variety.


Why has ESA never flown a crewed spacecraft?

Question: According to Wikipedia, ESA has never had a crewed spacecraft. While this is reasonable, it's striking that no ESA crewed spacecraft is in development right now. What's the rationale behind this decision?
Comment: Philosophically, I don't believe that it makes a whole lot of sense for ESA to develop a manned space access capability.  As we move into the future, I believe that space exploration will become more and more globally cooperative in nature.  Since Earth already has three mostly independent efforts to advance manned space access (Russia, China, and the United States), ESA's efforts are probably best aimed elsewhere.  Casual research will reveal the multitude of tasks they currently perform - perhaps better than anyone else...
Comment: India is also about to have their human launch capability come on line.
Answer: From 1985 to 1992, ESA worked on a human space program, using the Hermes spaceplane (to be launched by the Ariane 5 then in development). This program was cancelled due to rising cost and the loss of a sense of urgency: having an independent crewed spaceflight program was seen as non-critical.
Basically they had 3 expensive programs: Hermes, Ariane 5 and the Spacelab laboratory (for use on the Space Shuttle) and could afford only 2 of those.

The project was subject to numerous delays and funding issues. In 1992, Hermes was cancelled, in part due to unachievable cost and performance goals, as well as the formation of a partnership with the Russian Aviation and Space Agency (RKA), which reduced the demand for an independent crewed spaceplane.

After that, the ISS program was built on almost world-wide cooperation in human spaceflight. ESA's crewed program supports the ISS with astronauts, training facilities, ISS modules and (a few years ago) a series of cargo flights using the ATV.
ESA's long-term plans are visible in e.g. the Future Launchers Preparatory Programme, and that does not include a crewed capability.
More in general, the 2016 "Shared Vision and Goals for the Future of Europe in Space" contained (among others) these goals, which point to uncrewed launch capability only:

ensure availability and foster the competitiveness and reliability of Ariane, Vega and Soyuz from Europe's Spaceport;
ensure that Europe can respond to evolving market demands by developing Ariane 6 and Vega C and their ground infrastructures;
prepare a future for Europe to better serve institutional and commercial markets by focusing on innovative technologies, investigating future launcher evolutions, demonstrating technical capabilities and preparing routine access to and return from space.

As to why ESA isn't working on a human spaceflight program, I think cost is the main reason. It took years of negotiation among member states to reach agreement on the development of Ariane 6 - a development that's both relatively cheap and aimed at cutting the cost of a launch by 50%. An independent crewed program would be a bigger investment than member countries are willing to make. Participation in the ISS gets ESA most of what they want/need (access to a research lab in space).
Finally, ESA is involved in NASA's crewed spaceflight program: they're building the service module for Orion, based on the ATV.
Comment: ESA is working with Sierra Nevada on an Europeanized Dream Chaser (under the rather awful DC4EU name), in order to obtain a reusable orbiter at lower cost and development time. While the idea is to initially use it for unmanned cargo missions, crewed ones aren't out of the question. There is also a slow-burning suborbital passenger spaceplane (like Buran or X-37, launched by a rocket and landing like a plane) project for about fifteen years. But with only a trickle of funding, it is moving rather slowly. And there's Skylon that received some funding from ESA as well.
Comment: It is a space policy question.  Where would an ESA crewed spacecraft go?  The ISS will probably be gone before they could fly anything.
Comment: Thank you for your answer. Do you know something about the future? Even private companies are building crewed spacecraft, why ESA is not doing nothing in this direction?
Comment: I've added some that to my answer (there is some guesswork in the absence of an ESA page that says 'this is why we're not pursuing manned spaceflight).
Comment: @Organic Marble, it could go to the Moon or to Mars(?). Or perhaps, it could go to any international in-orbit "gateway" to a planetary journey. But perhaps, aside from cost, there is also ideology: space must not be a place where sovereingty is at stake but, on the contrary, a show case of human cooperations. The EU was keen to have the Chinese joining the ISS (my interpretation).
Comment: @NgPh to go those places they must also develop a lander for many more $. When I wrote that comment 4 years ago the situation (for example re: Gateway) was different than now. I always liked the ATV and wished it had been developed into a crewed vehicle.
Answer: I can add a little bit more to Hobbes' great answer. ESA cooperates extensively with NASA on a range of projects; the ISS is the biggest, but ESA and NASA are very enmeshed in each other's operations. Almost all of this cooperation is done on a barter basis, where on side provides, say, an instrument, and the other side provides launch, or whatever. The bartering doesn't even have to be within the same project: ESA gets "ISS credit" for some of their contributions to Gateway, for example. With this longstanding system, there's no point to develop an independent human launch capacity when you can instead just focus on the programs you've already developed expertise on, then just barter for the crew slots.


How can I disable jack sensing?

Question: I have a HP Pavilion Desktop computer running Windows 8 64 bit. I would like to use the sound card for something other than listening to music. The speaker jack has jack sensing. The only thing that seems to activate it is the speaker connector. I understand that there is supposed to be a edit to the registry that will defeat this function. My problem is the installed Windows 8 on this computer does not have the registry entry according to HP support. I find it hard to believe that anyone would build a computer that you can't use for other sound projects. If anyone can tell me how to by pass the jack sensing I sure would appreciate it.
Comment: What sound card? Driver you using for the sound?
Answer: Unfortunately there currently isn't any help for Windows 8. I used a cheap USB soundcard to bypass this pointless 'feature' which is on nearly all HP/Compaq desktops. It has something to do with the soundcard driver and as your desktop isn't Windows 8 compatible (according to HP, even though it works fine in all other respects)
My card was less than $5 - Same as this http://www.amazon.com/HDE-Channel-External-Sound-Adapter/dp/B0027EMHM6/ref=sr_1_2?ie=UTF8&qid=1366511293&sr=8-2&keywords=usb+soundcard
If you can find the same soundcard in their newer desktops then you could use those drivers, but HP sticking to the same anything in any hardware (apart from servers) - Is very unlikely for them to do.

How can I disable jack sensing?


What would oxygen or nitrogen snow look like?

Question: I was watching a video of what would happen if the earth got kicked out of the solar system and at one point it was mentioned that oxygen and nitrogen snow would form. So would such snow be any different physically to good ol' water snow? Would it be more fine or less dense? I'm asking this because I'm thinking of writing a story or something that uses that. Curiously, there seem to be almost no related results on the internet.
Comment: You may be interested in the short story "[A Pail of Air](https://en.wikipedia.org/wiki/A_Pail_of_Air)", which has a very similar setting.
Comment: I guess our ordinary water snow may vary widely in that how fine or dense it is. Then again, _a shape of individual snowflake_ is an interesting question in and by itself.
Comment: Have you ever discharged a CO2 fire extinguisher? How "different " would you say is that from regular snow?
Comment: @PeterMortensen Chemistry does bother with phase changes where there is no chemical reaction either. Similarly for the all the thermodynamics of ideal gas. Domains of interest are not sharp-cut, separated, boxed and labeled, but there are fuzzy boundaries, covered by interdisciplinary science.
Comment: It is [all physics](https://explainxkcd.com/wiki/index.php/435:_Purity) - there aren't ***any*** chemical reactions going on here. Why is this question on this site?
Comment: Welcome to chemistry stack exchange SomeMan. This is a beautiful question. I had not really considered it until you asked it here, thank you for that. Now let us hope some atmospheric chemist show us what is up (Ozone is the answer. Ozone is up).
Comment: Oxygen snow would be pale (or deeper) blue.
Comment: Neptune's moon Triton has a thin atmosphere that includes crystals of nitrogen ice: https://en.wikipedia.org/wiki/Atmosphere_of_Triton
Answer: I don't know if there would actually be oxygen and nitrogen snow. I would think under those circumstances, there might be carbon dioxide  snow, but the rest of the atmosphere would probably liquify first, there may be oxygen and nitrogen rain with some hail or sleet, but snow? Not sure it would happen.
If it did, oxygen and nitrogen snow would be different from our normal water based snow because of the absence of hydrogen bonds.
Individual snowflakes hexagonal in shape would not form, as this is a function of hydrogen bonds and this would not happen with oxygen or nitrogen. Water ice is also less dense than liquid water because of the way hydrogen bonds cause "voids" in the solid structure. This would not be the case with oxygen and nitrogen. So you'd probably get something more like needles than snowflakes.
Also, solid oxygen is blue as noted by Ed V below, so blue snow if it happens at all.
Qualifier:
If the earth is out there (beyond the orbit of Pluto) long enough, enough of the atmosphere would eventually freeze and the pressure may drop below the triple point of nitrogen. If that happens nitrogen would sublimate, then fall as snow as temperatures fluctuate.
But even Pluto's surface temperature and pressure is above the triple point of oxygen most of the time (temperature does sometimes drop below though) so any oxygen in the atmosphere would probably fall as rain (blue rain) or possibly hail/sleet rather than snow.
Another thing to remember is that if the atmospheric pressure is that low, there won't be much drag/resistance either, so no "softly drifting" snow. Those needles will reach terminal velocity pretty damn fast and shatter on the ground.
Comment: I also thought most of the atmosphere would come down as rain rather than snow. However, depending on how the atmospheric pressure changes as it cools, it may be possible to go below the triple point temperature/presssure of nitrogen and oxygen, at which point any further cooling would trigger precipitation as snow.
Comment: "Solid, liquid, and compressed gaseous oxygen is blue." Reference: First sentence of S.C Tsai, G.W. Robinson, "Why is Condensed Oxygen Blue?", J. Chem. Phy., 51(8), 1969, 3559-3569.
Comment: For both oxygen and nitrogen the triple point pressure is practically a vacuum, so that won't really come into effect. The triple point temps are both under -200°C but not absolute zero so I suppose it's not entirely impossible, but rather unlikely
Comment: Nitrogen's triple point is 63 K, 13 kPa (on the order of 0.1 bar). That is a bit more than vacuum. I don't think there is any liquid nitrogen on Pluto - it either sublimates or snows.
Comment: @Peter Mortensen Sure. But compared to cutrently? Earth would need to lose a large chunk of its atmosphere to get to that. And again, sure, Pluto's surface temperature is below the triple point temp of nitrogen anyway, even if the high atmosphere isn't, and its atmospheric pressure maxes at only 1-2Pa so yeah, nitrogen snow could be a thing there. Not so much oxygen, since it doesn't really feature in Pluto's atmosphere. That doen't mean the same holds for earth.
Comment: Also, from the surface pics of Pluto, it looks like most of the nitrogen ended up liquid first - ocean of nitrogen with water ice floating on top - before it froze


Unmerge [msi] from [windows-installer]

Question: A recent edit to the Manufacturer Tags question spotlighted a problem with an old action.  Five years ago, the post The msi tag is ambiguous identified that the msi tag was being used for both the Windows installer and hardware from the MSI company.  That led to merging or synonymizing msi with windows-installer without people realizing the implications.
It's always a bad idea to combine an ambiguous tag with one specific meaning because people will continue to enter the term in the tag window for the other meanings.  That results in an irrelevant or misleading tag on the question.  In the case of [msi], people following Windows installer questions waste time checking out questions about MSI brand hardware, plus it generally bloats the tags and dilutes their value.
There are currently 356 windows-installer questions.  I just glanced at the first of the eight pages of these, and spotted:

I had to re-install Windows 10, do I need to re-install the relevant drivers from MSI? posted in May is about an MSI brand laptop.
Trying to install new video card need assistance posted yesterday is about an MSI brand video card.
USB doesn't work under Windows 7 and MSI B450M posted in May is about an MSI brand motherboard.
Keyboard intermittent on MSI GT72VR 6RE posted in December is about an MSI brand notebook.
msi Notebook with Windows 8.1, can't start or boot is also about an MSI brand notebook.

So the mistagging is actually happening, and the total scope of it appears to be on the order of 10%.  We can go through the questions and delete that wrong tag, but it will continue to require cleanup and waste people's time if we don't separate msi.  So I'm suggesting that action.
I also suggest replacing windows-installer with msi-windows-installer.  That provides two benefits.  For users who are actually referring to the Windows installer, this would replace the synonymizing.  Without the direct link to msi, this would allow the Windows installer tag to show up when "msi" is typed.  windows-installer isn't a great tag, anyway, because msi isn't the only one and that tag doesn't make clear what installer it refers to.
Also, if a new user asking about MSI brand hardware types "msi" in the tag window, and windows-installer appears, there's no obvious connection for someone who doesn't do a lot of installation in Windows.  If they're paying attention and notice the tag, they may just assume the system added it automatically for some reason (like many other things about the site that don't make sense to new users).  Replacing windows-installer with msi-windows-installer will at least provide a mental connection to help the OP realize that what they typed means something else here.
Answer: status-completed
The msi -> windows-installer synonym has been removed.
We can now organise a proper cleanup of the windows-installer tag to remove any MSI-branded hardware questions.

Unmerge [msi] from [windows-installer]


Examiner Cited Disclosed Art 3 Years After the fact in a 102 Rejection

Question: I have an outstanding patent application that has gone through 5 Office Actions, 9 prior art citations, and one improper final office action withdrawn by the TC Director over the past 3 years. On the last Office Action, the Examiner cited art in a 102 and 103 rejection that I clearly disclosed in my specification in the original application. I am not sure the Examiner realizes it was cited originally, but aside from pointing out the mistake, are there any positions I can take to eliminate this art from consideration because she didn't address it for 5 office actions? It's worth noting this art is easily traversable (which I will address in the OA response), and was cited on claims that were previously allowed. (IMHO she cited the art as a punitive measure for my refusal to negotiate with her on claim scope, but I can't put that in the OA response). I think there is an argument that because the Examiner didn't previously see the 103 combination even though the art was known to her, it can't be obvious, but is there a legal argument to be made for estoppel, laches, or something similar?
Comment: Are you saying the specific cited art in the 102 and 103 rejections predate your filing? If you cited them in your application then, I assume, it predates your application.
Comment: The art is 15 years old. I cited it in the specification and explained why our art is different per USPTO rules. The Examiner cited the same art on the fifth action, after citing nine other pieces of art which were all traversed.
Comment: Sorry - I must have been asleep when I wrote the previous post.  I typed pre-date when I was thinking post-date. It doesn't matter how old it is or that you cited it. I agree with @Maca. While the concept of "compact prosecution" says they should throw everything at you on the first OA there is no rule protecting you from them later realizing something was more important than they thought initially. It is also possible that the art you are talking about was not the best art to cite against your initial claims but later claim amendments or arguments changed that picture.
Comment: @GeorgeWhite there weren't any claims amendments, so that didn't make a difference. The fact that claims were previously allowed is akin to a grant. Negation of a patent requires clear and convincing evidence of prior art. The Examiner has provided nothing more than a poorly cited recitation of our claim to parts of the prior art specification that don't match any sort of even remotely comparable elements.
Answer: No.
As a starting point, the USPTO is under an obligation to ensure that an application meets the various requirements before a patent is issued. That is, 35 USC § 131 provides:

The Director shall cause an examination to be made of the application and the alleged new invention; and if on such examination it appears that the applicant is entitled to a patent under the law, the Director shall issue a patent therefor.

The converse of this is that if an examiner does not believe the application meets the requirements, they cannot allow the patent to be issued.
Thus, until prosecution has been closed, there is no prohibition on raising a rejection based on new art, and indeed there is an obligation to do so. As such, there could be no basis for equitable procedural limits, like estoppel or laches.
Neverthless, if you believe there has been some procedural impropriety, there are two options. You could contact the examiner's supervisor (reasonably informal), or you could file an appeal to an office action (formal and costly).
Comment: I already interviewed the Examiner and SPE and it was fruitless. They both essentially stated the claims were too broad, which is not a bar to patentability. Since then, it appears their goal has been to force appeal by issuing frivolous rejections. I filed pro se under a micro entity claim. Are there any other remedies?
Comment: @bgmaster In that case, there is little else you can do, other than appeal. There is no way to force a new examiner: even if you filed a continuation, it would almost certainly be assigned to the same examiner.


Gaining root acces/installing custom rom on G1 with build number CRC1

Question: Could you please share your knowledge about how to flash the latest update of stock Android OS on G1 (aka HTC Dream)? I would like to try out some custom roms, but most information I was able to find relates to the RC30 or R33.
Comment: See also http://android.stackexchange.com/questions/1184/how-do-i-root-my-phone and http://android.stackexchange.com/questions/1/ive-rooted-my-phone-now-what
Comment: Kamil, A lot of folks are pointing you off site here (XDA, Haykuro) but I wanted to add that if you have specific questions as you go (like ... "how do I boot into recovery mode on the G1" http://android.stackexchange.com/questions/7160/why-cant-i-boot-into-recovery-mode)  definitely don't hesitate to bring them here.
Answer: I think you will have better luck at the XDA developers forum
It's the main place for ROM cookers (mainly HTC devices), for the Dream follow this link.
Try this thread for more info on rooting your HTC
Answer: I agree with palehorse, Haykuro's blog is very easy to follow and is where I learned the process. Once you are ready for a custom ROM, the best, by far in my opinion, are released by cyanogen. This is mostly due to their very fast speed compared to other ROMS.  You can find the latest, as of me writing this, at: his post on XDA Developers
Comment: Agreed, I just updated from JF1.5 ADP to the most recent cyanogen rom (4.0.2 now) and I am loving it.  Automatic apps to SD, swap on SD, and it seems to perform quite a bit better than the official TMO and JF roms.
Answer: This tutorial on Haykuro's blog was very easy to follow.  I used it up to the point of flashing with the ROM I wanted.


Progress Bar in Excel 2013

Question: I have a training doc on Excel, with multiple sheets, showing multiple tasks that need to be done. On the home page (worksheet) I would like to show a progress bar showing the amount of tasks complete as a percentage. Is this possible? How can I do it?
Answer: Yes, it is definitely possible, take a look:
Using Excel 2013's conditional formatting features, you can create progress bars on your spreadsheets. Progress bars are used to graphically represent the advancement of the data. Essentially, you get a chart-like effect within the rows and cells themselves.
Below is an example of the setup that you should have before you start. I will use Cold/Hot as my demonstration. I also stretched the E cell to make the progress bar longer. This is done to see a more accurate bar, but this step is not a requirement. As you can see, I put the number 12 in the progress bar cell. This number will be the percentage of the bar that is shaded.

From the Excel ribbon, select Conditional Formatting and then Data Bars. Next, select More Rules..

Now, you should see a window which will allow you to create a new formatting rule. For this step, we want to adjust the settings as follows:
Type: Chose Number, both Minimum and Maximum.
Value: Set the Minimum value to 1 and the Maximum value to 100.
Finally, chose your color, and click OK.

f you have adjusted all of the previous settings correctly, you should now see a progress bar.
Comment: @stevehilton You are welcome! Fell free to mark this answer as accepted ;)

Progress Bar in Excel 2013