find $f(x)$ when $3f(x-6)-2f(x-9)=x^2-54$

Question: I can easily show that with the assumption $f$ is a polynomial $f(x)=x^2$. But without that assumption how can I prove that $f(x)=x^2$???. I have tried many change of variables $x=u+k$ but to no result. I am lost here
Answer: Let $g(x)$ be so that $3g(x)-2g(x-3)=0$. For example, take any periodic $h(x)$ on $[0,1]$ and let $g(x)=h(x/3)\left(\frac23\right)^{x/3}$. Then $g(x)+x^2$ also satisfies your equation. So there are many solutions to your equation.
Answer: Let $f(x)$ be polynomial of $x$.
Let $n\ge 3,$ be the smallest power of $x$ whose coefficient$(a)$ may be $\ne 0$.
The coefficient of $x^n$ in $3f(x−6)−2f(x−9)$ is $3a-2a=a$
But the coefficient of $x^n$ where $n\ge 3$ in $x^2−54$ is $0\implies a=0$
So, $f(x)$ can not contain any higher powers $(\ge 3)$ of $x.$
So, $f(x)=bx^2+cx+d$
$3f(x−6)−2f(x−9)=x^2−54$
$b(x-h)^2+c(x-h)+d=x^2(b)+x(c-2bh)+(d-ch+bh^2)$
The coefficient of $x^2$ in $3f(x−6)−2f(x−9)$ is $3b-2b=b$
But the coefficient of $x^2$ in $x^2−54$ is $1\implies b=1$
The coefficient of $x$ in $f(x−h)$ is $c-2bh=c-2h$
So, the coefficient of $x$ in $3f(x−6)−2f(x−9)$ is $3\{c-2(-6)\}-2\{c-2(-9)\}=c$
But the coefficient of $x$ in $x^2−54$ is $0\implies c=0$
The constant term  in $f(x−h)$ is $d-ch+bh^2=d+h^2$
The constant term  in $3f(x−6)−2f(x−9$ is $3\{d+(-6)^2\}-2\{d+(-9)^2\}=d-54$
The constant term  in $x^2−54$ is $-54\implies d-54=-54\implies d=0$
So, $f(x)=x^2+0x+0=x^2$
Comment: +@lab nice work!
Comment: @amWhy, thank, please have a look  into the edited answer.
Answer: The following note - for a general functional equation which is related
Assume that $F=\mathbb{Q}$, $\mathbb{R}$ or
$\mathbb{C}$ and $V$ and $B$ are vector spaces over $F$ and $X$ is a
Banach spaces over $F$.
A function $a:V\rightarrow B$ is said to be additive provided
$a(x+y)=a(x)+a(y)$ for all $x, y\in V$; in this case it is easily
seen that $a(rx) =ra(x)$ for all $x\in V$ and all $r\in \mathbb{Q}$
[1].
If $k\in \mathbb{N}$ and $a:V^{k}\rightarrow B$, then we say that a
is $k$-additive provided it is additive in each variable; we say
that a is symmetric provided
$a(x_{1},x_{2},...,x_{k})=a(y_{1},y_{2},...,y_{k})$ whenever
$x_{1},x_{2},...,x_{k}\in V$ and $(y_{1},y_{2},...,y_{k})$ is a
permutation of $(x_{1},x_{2},...,x_{k})$.
If $k\in \mathbb{N}$ and $a:V^{k}\rightarrow B$ is symmetric and
$k$-additive, let $a^{\ast}(x)=a(x,x,...,x)$ for $x\in V$ is and
note that $a^{\ast}(rx)=r^{k}a(x)$ whenever $x\in V$ and $r\in
\mathbb{Q}$. Such a function $a^{\ast}$ will be called a
monomial function of degree $k$ (assuming $a^{\ast}\neq 0$).
A function $p:V\rightarrow B$ is called a generalized
polynomial} (GP) function of degree $m\in \mathbb{N}$ provided
there exist $a_{0}\in B$ and symmetric $k$-additive functions
$a_{k}:V^{k}\rightarrow B$ (for $1\leq k\leq m$) such that
$$p(x)=a_{0}+\sum_{k=1}^{m}a_{k}^{\ast}(x)\ \ \ for\ all\ x\in V,$$
and $a^{\ast}_{m}\neq 0$. In this case
$$p(rx)=a_{0}+\sum_{k=1}^{m}r^{k}a_{k}^{\ast}(x)\ \ \ for\ all\ x\in V\ and\ r\in \mathbb{Q}.$$
Let $B^{V}$ denote the vector space (over $F$) consisting of all
maps from $V$ into $B$. For $h\in V$ define the linear
difference operator $\Delta_{h}$ on $B^{V}$ by
$$\Delta_{h}f(x)=f(x+h)-f(x)\ \ \ for\ all\ f\in B^{V} and\ x\in V.$$
Notice that these difference operators commute
($\Delta_{h_{1}}\Delta_{h_{2}}=\Delta_{h_{2}}\Delta_{h_{2}}$ for all
$h_{1},h_{2}\in V$) and if $h\in V$ and $n\in \mathbb{N}$, then
$\Delta_{h}^{n}$--the $n$-th iterate of $\Delta_{h}$--satisfies
$$\Delta_{h}^{n}f(x)=\sum_{k=0}^{n}(-1)^{n-k}(_{k}^{n})f(x+kh)\ \ \ for\ f\in B^{V}\ and\  x,h\in V.$$
The following theorem were proved by Mazur and Orlicz [2] and
[3], and in greater generality by Djokovi$\acute{c}$
[4].
Theorem:
If $n\in \mathbb{N}$ and $f:V\rightarrow B$, then the following are
equivalent.
$\Delta_{h}^{n}f(x)=0$ for all $x, h\in V$.
$\Delta_{h_{n}}...\Delta_{h_{1}}f(x)=0$ for all $x,h_{1},...,h_{n}\in V.$
$f$ is a GP function of degree at most $n-1$.
for more information see http://arxiv.org/abs/1210.4975v1
Comment: With the above theorem can we proved that $f$ is a monomial function of degree 2.


Ice the wort for fast cooling

Question: I have seen mostly two suggestions to cool wort.  Ice bath and the coil method.  My friend and I were thinking about just using ice.  Ie pull the ice from the fridge that uses the same water source as used during the boil.  Put it in the pale and run the wort into the ice.  What are the drawbacks, I'm sure there are some because I can't find anybody recommending this method.  For sure it will cool down pretty quickly which is desired.
Answer: I always thought of this as being a HUGE no no. But I guess not...below is from John Palmer.

People often wonder about adding ice directly to the cooling wort. This idea works well if you remember a couple key points.

Never use commercial ice. It can harbor dormant bacteria that could spoil your beer.
Always boil the water before freezing it in an airtight container (like Tupperware). It must be airtight because most freezers also harbor dormant bacteria.
If the ice will not directly contact the wort, (i.e. you are using a frozen plastic soda bottle or other container in the wort) make sure you sanitize the outside of the bottle first before you put it in the wort.
Comment: This is good advice, I think.  I haven't had any problems with my brews so far but that could just be good luck.
Comment: I do use ice directly in the cooling wort. I do not boil water before frozing it, I do use water bought at the supermarket (Evian French water). Never met a problem with bacterias !
Answer: This is how I do all of my brews.  I usually boil about 11/12L for a 20/21L batch, put a filter over the primary bucket, pour the wort in from a bit of a height to help aerate, add ice until I get the right temperature then top up with water.  The "right temperature" might be a couple of degrees above / below target, depending on whether the top up water is warm or cold.
I haven't had any contamination problems yet, but it is something to keep in mind.  Either make your own ice through freezing boiled water (you'll need a few kgs) or buy it bagged from somewhere you trust that takes cleanliness seriously (distilled, minimal handling, etc).  Some places do sell different grades (e.g. triple frozen for making cocktails) so you might be able to find something especially good.
The temperature gets down within a few minutes so it's certainly an effective method.  Plus you save potentially hundreds of litres of water per brew.  This is the reason I do it: I haven't found a more efficient wort cooling system than this.  As baka noted though, it will not work if you are doing a full boil and will become harder as you get closer to a full boil.
Comment: We did the second batch today using the same method.  I bought 3 gallons of distilled water and froze it.  When we start boiling I take it out of the freezer, by the time it's needed it will have melted enough on the outside so I can just cut up the plastic container and put the ice in the pot.  This chills the wort down in a few minutes.  After two batches we know pretty much what the level needs to be in the pot before putting the ice in to end up with 5 gallons at about 72F.
Answer: The only problem I can think of might be contamination or (depending on the age of your ice...) picking up off flavors from the ice.    Remember that it will also dilute your wort by some (probably calculable) amount.   If you're doing a concentrated boil anyway, then it would be easy enough to dump the hot wort onto your extra 2-3 gallons of ice.   I imagine that it would get you to pitching temperature more rapidly than other methods, as well.

Ice the wort for fast cooling


What is the purpose of slow experience gain in Pathfinder Society Organized Play?

Question: Pathfinder Society Organized Play allows players to advance either 1XP or 1/2XP per session.  There are no advantages offered by taking the slower XP (experience) gain, so why would someone use this option?
Answer: The relevant bit of the Pathfinder Society Field Guide:

At character creation and each time you gain a level, you decide if
  you would like your character to be on the standard or slow
  advancement track for the entirety of that level.

Primarily, the "slow" XP gain is so that you can keep playing with a particular character longer. Note that when you gain a level you pick whether you are on the slow or normal track for the next level. There are a couple of reasons you might do this:
Hypothetical 1: I like playing PFS with my friends, but I attend more games than they do
I might decide to do ½ XP for a few levels, so that I'll stay in the same tier with them.
Hypothetical 2: I really love this character, but I'm approaching the level 12 cap too rapidly!
I might then do ½ XP to prolong the life of that character.
Hypothetical 3: I GM a lot of PFS games, and all of my characters are getting XP, but I've not had time to play them
Might choose ½ XP for a level or so, in order to actually get to play the character at that level.
In the end, it's just a way to stretch out the pacing of PFS games, since there's not a lot of end-game content at level 12, and if you play a lot, you'll be leveling up fairly quickly.
Comment: It is also the case that depending on where you are there may not be a lot of other players in PFS with characters at a given higher level - so you might choose slow advancement to stay at the level of play available near you for longer.
Comment: Living Greyhawk didn't have this rule, and actually punished people for avoiding character retirement, and Pazio appears to just think it is silly to punish players for trying to play a beloved character a bit longer.
Answer: Slow advancement also offers the additional benefits:

Twice as many Day Job checks (which means more free gold between games)
If you have the Borderland Keep vanity property, you can get 2 prestige points per slow advancement.
Twice as many chances to receive a Boon at the end of an adventure.
If you're a Druid or Ranger, twice as many chances to teach your animal companion a new trick.
If you're a spell caster, twice as many chances to learn a new spell from a scroll.
Twice as many chances to make saving throws to remove a carry-over affliction.
Basically, twice as many chances to do anything that is normally permitted only once between game sessions.
Answer: I've found with newer players that the longer they play a level the better grasp they have on the class and character, as they can spend more time mastering and getting comfortable with the abilities/feats/spells.
Comment: I agree with that completely: I found LG rammed me through the levels so fast that I was still figuring out my new spells when I levelled.
Answer: The reason I chose to do this when I played is so I can understand the classes better that I never play at a non-organized play setting.  This allows me to find the classes quirks and as a DM helped me challenge my players that played the classes I never played before.  It also helped me realize that I really enjoy the Witch class.


How to fill a gap behind plastic baseboard

Question: I've added a waterproof plastic baseboard. Cut the angle at the door join at 45 deg which shows a predominant gap. I could just caulk it, but it would look terrible. What would be a good filler that wont crack and can be sanded and painted?
Comment: Too late to be an answer, but I'd have brought it to the door jamb and then cut it at 90 degrees, and used caulk or filler to make the cross-grain cut smooth before painting.
Comment: By a piece of self-stick vinyl floor tile of the appropriate color, cut a piece to fit, and glue it on.
Answer: You should really do a mitered return on that edge and terminate it into the wall.  It will require a 45 cut in the opposite direction and a small piece, also cut at a 45 to fill the gap to the wall.

Here is an example
Answer: Gary Bak's answer is good. You can also do an angled return if you wish to ease the transition a bit. This involves a 22-1/2° angle on the main piece, and one 22-1/2° and one 45° on the return piece. Watch your fingers!

image source
Comment: It wouldn't be that difficult to cut the angle the opposite way on the installed piece. Since you're caulking anyway it doesn't have to be perfect.
Comment: These look good, but I've already glued/nailed the baseboard down. Just need to fill the gap, sand and paint. Won't look as good, but I think I can still get it to look decent. What would be a good fill material?
Comment: @TchaiQuentin: I'd replace it and do it right, but if you want to make it look good without taking it out, you could get some acrylic resin for automotive body repair and build out the missing material, then carve the return (like in Gary Bak's answer) using a rotary tool or the old fashioned way. All the (finished wood) returns on my home's lower window casing, and some other trim parts, were done this way, and I was able to duplicate it easily (on other wood parts, but the process should be similar for filler material) when I needed to.
Comment: removing it seems much easier to me than doing all the proposed adjustments/workarounds.  I assume it is attached with few brad nails.
Answer: Any non-shrinking wood putty should do. Elmers, Minwax, and Durham's offer good products. You could also use a setting-type joint compound, such as Durabond.
Comment: Automotive Bondo works wonders with wood as well. Dries fast and sands well.
Answer: I would cut a piece of wood to fill as much of the gap as possible ( can be secured with either adhesive and/or nailed into place ).  You can then fill the remaining small gaps with your choice of wood putty and sand/paint.
Answer: Another option is to just add a decorative base block moulding.  They are available in a variety prices and styles.  This would look nice and work well if you are not skilled enough to do the mitered solutions cough like me cough suggested in other answers.
Here's a link to one at a big box store.
Answer: The Right Way to terminate baseboard is without any return or diagonal cuts, running it into plinth block at the bottom of the door casing. If you want to do this, you can probably do a 45-degree cut the opposite direction on a piece of leftover baseboard material to replace/extend what you already cut and cover up the seam when you paint. While OP's photo indicates that the current door casing does not have plinth block (it just runs all the way into the floor), if there's a reason the baseboard needs to be waterproof then it might make sense to also replace the bottom of the door casing with a suitable waterproof plinth block so that it's protected too.
Short of that, you can achieve a result like Gary Bak's answer (which also looks nice) without ripping out what you've done. I see two ways to do it:

Build up the missing material with filler (I'd use acrylic resin for automotive body repair, but other materials would work too), carve a return to match the baseboard design using a rotary tool with carving bits or unpowered carving tools, and sand it smooth with the existing baseboard before painting. Or,
Prepare a short (e.g. 1-2") piece of baseboard with the mitered return as described in Gark Bak's answer, cut off just enough of the end of your work (including the whole 45-degree part) in-place, and glue the attach the replacement in.
Comment: @FreeMan: Indeed, but I think it's still worth mentioning because if OP has a need for waterproof baseboard (looks like a basement with flooding risk?) then getting something waterproof (a plastic or other artificial material plinth block) at the base of the door casing would probably be a really good idea too.
Comment: This is _a_ `Right Way™` to do it, especially if you already have a square cut plinth block at the bottom of your door trim. However, the picture in the OP shows that he does _not_ have a plinth block there, but instead has `Standard cheap American door trim™` which would require a different finishing technique.
Comment: Your comment about getting the wood off the floor to protect from water damage is a good one that should be in your answer, not a comment. However, your emphatic "Right Way" comment may lead a newbie to believe that this is the "Only Way" when clearly it isn't. Additionally, there is a lot of PVC trim material being sold in American big box retailers that happens to be waterproof - I'm sure a lot of it is being used in areas where the waterproofness of it is of no great value to its installation location.
Comment: @FreeMan: Integrated into answer. Better now?
Answer:
I could just caulk it, but it would look terrible.

If you caulk the top of the baseboard(gives it a cleaner look) then you can caulk this side easily and it won't look out of place. A tube of basic white caulk doesn't cost a lot.
Comment: It'll shrink badly in that large void, though.
Comment: Yeah, might need some of your putty answer first
Comment: First yes, but then caluk second.
Answer: I would add a plinth block (as mentioned also in R.'s answer). If you have a moisture issue in this room you could get one made of waterproof material, and you will have a more finished look when you're done.
If you measure and cut very carefully you can do this without removing the existing trim (other than what you're replacing with the block).

Choose a block that's taller than your baseboard (around 2 inches/5 cm is standard, but I've seen blocks that were both shorter and taller than that) and wider than your door trim (1/4" or probably 1/2 cm wider is standard, but you may need to go a little bit wider than that to make sure you can cover the gap left when you cut off the beveled part of the baseboard) and deeper than both. If you have plinth blocks elsewhere in your house try to find something that is similar, or if there's a particular style of trim that you're adding in this room you could coordinate with that. Otherwise, something fairly plain will draw the least attention.
Measure your block and the space two or three times, and mark where you want to cut across the door molding and baseboard. Measure up from the floor on both sides of the casing. I would set the block in place and eyeball my marks, too, just to make sure there isn't anything wonky with the floor (but I've only done this in really old houses, where there's always something wonky with the floor). If you have to err, err a bit on the side of cutting less, since you can always cut more.
Use a hand pull-saw or something like a dremel to very carefully cut through the trim, being careful not to mar the floor or wall. (If you have room, you might want to slide a piece of cardboard or something like a floppy plastic notebook cover between the trim and the floor.) These will be 90° cuts, perpendicular to the wall.
Carefully remove the trim from the wall. You may want to score behind it with a utility knife, and use a putty knife to help pry it free. It's OK if there's a little bit of damage to the paint behind the trim you're removing, because the block will cover it, but you don't want damage that extends beyond what the plinth can cover.
Pull leftover nails and clean any glue or excess paint off the wall, so you have a smooth-ish surface. Again, dings behind the block will be hidden, but you want it to be able to lay smooth against the wall so you don't want nail heads or anything else protruding.
Set your block in place. Typically it would be centered on the casing, but you may need to have it be wider on the outside of the door (toward the baseboard) to fill your gap. If it fits, great! Attach it as you would other trim, caulk, and finish. If it's a bit too large, you can either sand the existing trim or the block (or both) so that it fits. Hopefully you won't have much of a gap, but if you do this installation is pretty forgiving of filling and caulking—one of the purposes of these blocks is to disguise less-than-perfectly-true dimensions, and to avoid the need for precision angle cuts.
Answer: The base block and miter solutions already proposed are certainly the prettiest answers. If you really want to use a filler, a coworker of mine has used Kwik-Poly. It mixes like a 2-part epoxy and will sand and work like wood once it's hard and is paintable.


Can a competitive miner be crafted at home?

Question: Ive been wondering, is it possible to make a good custom Bitcoin miner? AntMiners aren't worth it anymore, and I can't find a miner that is. Can I build a miner myself that will be worth it? If so, what do I need to custom make a miner? What are some basic Bitcoin miner components. How much will it cost approximately? Is there anything else I need to know if i'm going to build a miner? There was some confusion, I don't mean I want to print my own pieces and make my own miner completely from scratch, I want to buy pieces online and make a miner, can I do this somehow?
Comment: The last time I heard pricing of the engineering costs it was in the $500,000+ cost range to develop an asic
Comment: Two words. Holy Crap.
Answer: No, the ASIC chips used in miners are impossible to craft at home, and to my knowledge no competitive chips are for sale as component parts.
Development of new ASIC chips has progressed to a level where it costs millions to create a new template and you need state of the art (<16nm) production to produce them. It is not economic to do this at home.
Answer: Unless you live in an area with extremely cheap (or free) electricity, you probably will not be able to build your own miner from scratch.  Modern mining requires ASIC's (Application Specific Integrated Circuit) in order to make any money.  These are silicon chips that implement the SHA256 hashing algorithm in hardware, rather than running a software version of the algorithm on a general purpose CPU, or even GPU.  Unless you are able to manufacture your own custom silicon chips, you would be better off purchasing an ASIC miner.
Answer: The closest you will come from the comfort of your home is an FPGA, which basically allows you to implement a customized circuit that is for you application. If you are not familiar with the SHA-256 hashing function and Bitcoins implementation of it, it could take you a long time.
This would never be better than simply buying an ASIC. It will not be more efficient. But if your goal is to learn, then you could try.
Answer: You could build your own miner if you have the technical knowhow and equipment using a batch of Bitfury 75GH/s chips, however, the idea of doing this at home is not going to happen. I am told that Bitfury has a minimum order of USD 2 M for all products (EDIT: seems they may have changed their policy) but, you might be able to find smaller quantities on eBay or elsewhere online. For USD 2 M it is more likely you might start producing en-masse in your garage. You might have more luck finding a retailer selling 55TH/s, 5.6kW Bitfury B8 servers or a Bitfury Block Box.
I am not affiliated with Bitfury.
If anyone finds any useful non-eBay links for these products post them in the comments and I will update my answer.


Correlation between Beta distributions

Question: I have a Computer Science background and not very knowledgeable in Probability and Statistics. So excuse me if my question,notation, or language is flawed. Anyways, the problems is that we have two Bernoulli variables $X_1,X_2$ that generate sequences of values for $n$ consecutive Bernoulli trials. Now we have $m$ independent observations of those trials in discrete independent time-slots. For example:
let:
 $n=4, m=3$
The result of the aforementioned trials is:
for $X_1: ((1,0,0,1),(0,0,1,1),(0,0,0,1))$
for $X_2: ((0,0,1,0),(0,1,1,0),(0,1,0,0))$
where each of "inner-sequences" is one of $m$ independent sequence of Bernoulli trials. Now we aggregate each of those "inner-sequences" into a Beta distribution function to represent the posterior probability of success/failure of each variable in different observation. For instance the above sequence transforms to the following
$X_1:(B_{11},B_{12},B_{13})$
$X_2:(B_{21},B_{22},B_{23})$
where each $B_{ij}$ is a Beta distribution function associated with the corresponding sequence of trials in the previous part of the example.
Now we a have two sequences Beta Distribution where we want to use in order to find the correlation between $X_1$ and $X_2$ preferably producing a final beta curve that shows the degree of correlation between $X_1$ and $X_2$ incorporating the factor of uncertainty, or a Gaussian curve. A very simple approach is to find the correlation based on the mean of the curves and using the Pearson's correlation method. However, this is not precise enough. Is there any method to find the correlation between two Beta distribution functions. An easier question is where can I find useful information about the detection of correlation based on two distribution functions of any kind (easiest should be Gaussian functions). Thank you so much in advance.
Amir
Answer: You can apply ranks and then use Pearson correlation on the ranks, but ranks are known to have a rectangular distribution instead of Gaussian(normal).  Instead, use Spearman rank correlation.

Correlation between Beta distributions


Arch Linux: Strange version mismatch when trying to install UWSGI with pacman. Is this common / trivial?

Question: When I run pacman -S uwsgi or pacman -S community/uwsgi I get the following error:
resolving dependencies...
looking for inter-conflicts...

Packages (6): jansson-2.5-2  libxml2-2.9.1-5  libyaml-0.1.4-3
              python2-2.7.6-1  sqlite-3.8.2-1  uwsgi-1.9.20-1

Total Download Size:    0.27 MiB
Total Installed Size:   69.85 MiB

:: Proceed with installation? [Y/n] Y
:: Retrieving packages ...

error: failed retrieving file 'uwsgi-1.9.20-1-x86_64.pkg.tar.xz' from
    archlinux.mirrors.uk2.net : The requested URL returned
    error: 404 Not Found
warning: failed to retrieve some files
error: failed to commit transaction (download library error)
Errors occurred, no packages were upgraded.

This would indicate to me that the package is not on the server.   However I tried a number of mirrors and got the same result.
I then investigated further, by directing my web browser to the mirror directory and confirmed that there is a uwsgi package there, but the version is later:
uwsgi-188.8.131.52-1-x86_64.pkg.tar.xz

I am fairly new to Arch so don't know if I'm missing something obvious here.  On Debian my response would be to run apt-get update, but can't find a similar facility in pacman:  My understanding is that the -S option will take care of that as well as installing the package.
Could this be a case of mirrors not being synced properly, or am I missing something simple at the client end?
If the mirror contains a later version, why isn't my pacman command picking that up?
Answer: Synching my local mirror database and doing a system upgrade with pacman -Syu solved it.
Comment: Pretty new to Arch myself. I read [this](https://wiki.archlinux.org/index.php/Pacman#Installing_package_groups) in their wiki in particular a warning about partial upgrades and to never refresh the package list before installing an app. Indeed, if there was a new sync, one should do `pacman -Syu` before installing a package.


How do I add a Membership Expiry view-only field to a user profile page in Wordpress?

Question: I want to let members see their membership expiry date. I am running Civi 4.6 with Wordpress 4.4.1. I have tried creating a Membership Details profile with one field "Membership Expiration Date" in it, but whenever I try and view the field, I get "Profile search, view and edit are not supported for Profiles which include fields for more than one record type."
Answer: If you want to fetch this information directly, the following code should get you started. It displays the logged-in user's membership expiry date:
<code>// get current WP user
$user = wp_get_current_user();

if ( civi_wp()->initialize() ) {

    // get contact ID
    require_once 'CRM/Core/BAO/UFMatch.php';
    $civi_contact_id = CRM_Core_BAO_UFMatch::getContactId( $user->ID );

    // get CiviCRM membership details
    $memberships = civicrm_api( 'Membership', 'get', array(
        'version' => '3',
        'page' => 'CiviCRM',
        'q' => 'civicrm/ajax/rest',
        'sequential' => '1',
        'contact_id' => $civi_contact_id,
    ));

    // show expiry date
    echo $memberships['values'][0]['end_date'];

}
</code>
Obviously your production code would include error checks after fetching the CiviCRM Contact ID and the Memberships that they may or may not hold. It would also convert the date to a more friendly format.
Answer: What other field types have you added to the profile? Can you add a screen shot of the fields you have included? If you have allowed access on the front end to the contact dashboard, you can include expiration date there, without having a separate profile.
Answer: Why not just use the User Dashboard and select which elements you want to show?
From the online CiviCRM Book:
When selecting the User Dashboard you get no additional options. To identify what related information you have setup to be displayed within the user dashboard i.e. Contributions, memberships, etc. navigate to Administer > Customize Data and Screens > Display Preferences and select all of the information you would like to have visible to the user.


OpenVPN with iptables and a tun interface

Question: With an openvpn tunnel that uses a tun device, what iptables rules allow the encapsulated traffic through and what rules control the packets after encapsulation? Basically, I am wondering how the order of operations works with iptables and openvpn as well as how this relates to the chains.
Answer: Plaintext traffic will go in and out of the tunX devices; you may find the -i tun+ and -o tun+ options to iptables, which match any tun interface, useful in handling that.
Encrypted traffic will be UDP/TCP on port 1194, or otherwise, as you have specified, on your ethernet interface.  When filtering traffic into the server, don't forget to allow the OpenVPN encrypted packets.
And as for chains, encrypted traffic coming in is considered to terminate on the openvpn server, so that's the INPUT chain; encrypted traffic leaving is considered to have originated on the server, so that's the OUTPUT chain.  Traffic passing between your internal network and the tunX interfaces is the responsibility of the FORWARD chain.
Answer: For traffic coming through the tunnel, you just need to set up FORWARD rules to allow the traffic from the tun interface to the eth interface. Such as the following rule allows access from tun0 to RDP for the specific range.
-A FORWARD -i tun0 -p tcp --dport 3389 -d 192.168.0.0/24 -j ACCEPT
After the forward rules, if you have an established/related rule on the eth interface, it will allow the traffic back through.


How does Rediff calculate MVPI (Most valuable player index) for IPL?

Question: I have come across a lot of Rediff articles, where they give MVPI rankings. Before a series, after a series, IPL etc. How do they calculate this? What is the formula? What are parameters of the formula?
Answer: Check for the source
The Most Valuable Player Index (MVPI) picks out batsmen who score a lot of runs at a high strike rate, bowlers who take a lot of wickets at a low economy rate, and fielders who take the most catches or participate in run outs.
MVPI expresses a player's overall batting + bowling + fielding performance in terms of a 'run equivalent'.
MVPI: Most Valuable Player Index = Sum of batting, bowling and fielding points. Run outs are counted as 1 (wicket) for a direct hit, and 0.5 (wicket) if the fielder is an equal participant in a run out dismissal.


Whats the best way to embed a video from Facebook's Graph API?

Question: I am trying to show a video that's returned from Facebook's Graph Api.  I have the source of the video which is either a YouTube video, Vimeo video, Facebook Video, or any other type of video that is posted to the news feed.
My $facebookdata returns this:
[source] => http://www.youtube.com/v/PwD4t9gcLb4?version=3&autohide=1&autoplay=1

I've been setting the value of SOURCE to $status_video_embed like so:
$status_video_embed = str_replace("autoplay=1", "autoplay=0", $data['source']);

Also, you can see I am replacing the autoplay to 0 if it exists.
I've been embedding the videos to be displayed like this:
echo '';

This works but I am running into a few problems.  First, if it's any video other than a Facebook video it plays fine, but I can't make it fullscreen.  I am assuming this is because it's embedding in an iFrame.  Second problem is with Facebook uploaded videos, they autoplay, and I can't figure out how to prevent autoplay with those videos.
The second approach I've taken is this:
echo '<object width="350" height="197" ><param name="allowfullscreen" value="true" />';
echo '<param name="movie" value="' . $status_video_embed . '" />';
echo '<embed src="' . $status_video_embed . '" type="application/x-shockwave-flash" allowfullscreen="true" width="350" height="197"></embed>';
echo '</object>';

This displays the videos - except they take forever to load and display - it prevents the facebook videos from autoplaying, but now, when I click play on any video, nothing happens.  No controls through the embedded video works.
Does anyone have any idea what the best way to embed a video is in this method?  I am given the source to the video from the returned array.
I hope someone can help, thanks.
Answer: Why dont you just develop your own player in HTML5, And parse the video page for the URL??


Rogaine or hair loss medications

Question: Are there any Halachik or Hashkafic issues with using rogaine or some other hair loss prevention medicine?
Comment: Please edit something into this question as to what halachic problem(s) there might be? I'm unaware of any halachic problems (other than, perhaps, on Shabbat and Yom Tov) of using any type of topicals for any reason.
Answer: It is clear from this answer of R. Elchanan Lewis, that there is no problem:

It is a standard treatment for men and is not a problem of Beged Isha.
From what I read on their website I can't see any Halachic problem
  applying the treatment apart from the issue of pulling out hair,
  therefore if one can't apply the Rogaine without pulling out hair that
  may be a reason for refraining from its usage on Shabbat.
If you can avoid the treatment by applying right before and straight
  after Shabbat, that will be better.

From the discussion it is evident that sans Shabbat issues, there is no problem.
Comment: @DanF It isnt. That's the point. I am not here to defend every question anyone ever asked. People frequently as ill-informed questions, and questions based on mistaken assumptions.
Comment: What could be *begged isha* about using Rogaine??? It's a topical medication, not clothing.
Comment: Got it. I will have to access the source from another machine. The assumption of *begged isha* is so crazy that I think the person who asked about that concern has bigger problems inside his head than outside of it :-)

Rogaine or hair loss medications


Who evaluates Marie Curie Intra-European Fellowship proposals?

Question: Who are the evaluators of the Marie Curie Intra-European Fellowship proposals? Other academics ? How are they selected ?
Answer: You will find details on the evaluation process in the Guide for Applicants. The evaluators are experts (=researchers) in the field. They will be matched to the proposal according to their profile and to the abstract and keywords. They will for sure be in the general research area, but might not be in the exact same field of the proposal. It is (at least, officially) not possible to find out who evaluated the proposal afterwards, but you can find a list of former evaluators here:
http://cordis.europa.eu/fp7/experts_en.html
Answer: Who are the evaluators...? I am. Along with a few hundred other people, of course! The evaluators ("experts" in EU jargon) are mostly academics from across Europe, with a decent number of scientists from industry, government, etc.
How are they selected? There is an open application process to become an EU H2020 expert. You fill out a form on the H2020 website, where you detail your scientific expertise, list your publications, grants etc. Then there is some selection process where, if your profile matches a vacancy on one of the evaluation panels, you get invited to be a panel member.


Adding a API to WSO2 API Manager that has OAuth credentials

Question: We're trying to test out WSO2 API manager and having troubles adding some APIs. MailChimp was added easily because MC has not OAuth Credentials itself. But when trying to add Facebook or another API that has it's own API manager it doesn't work and constantly get a 401 Unauthorized. This is becaused both Facebook and WSO2 API Manager need OAuth tokens and obviously you can only send one Authorization header. Any help here?
Answer: WSO2 ApiManager 1.0 still does not support (OAuth) secured back-end services out of the box. Hence it is not possible to register facebook, twitter apis via APIM.
Right now, an application is sending and authorization header to the APIM with a key issued by the APIM. Ideally if you send another authorization header, that will be forwarded to facebook api, but at the API Gateway level you need to remove the processed header which belongs to the APIM authorization.
Adding backend services with security will be added as a new feature to APIM future releases.
Regards,
/Nuwan
Answer: Can you please explain why you want to use the API manager here? You can directly send your request to Facebook where the request is authorised.


Can I get all Hoenn and Kanto starters in Pokemon SoulSilver?

Question: I've been wanting to know for a while if it is possible to get all Hoenn and Kanto starters in Pokemon SoulSilver without cheats and without Wi-Fi.
Comment: Without cheats and **without trading**?
Comment: Without wi-fi trading, as stated in the original question (before edits).
Answer: If you have PKMN LeafGrean and PKMN Ruby (or their counter parts), you can use a feature to migrate PKMN up from them. All you need to do is choose a starter, catch 6 more PKMN, then transfer the starter up with 5 of the others (because you need 6 at once to transfer). Then you restart and repeat with the other starters and games.
Because you can get 1 Kanto Starter (by beating all Gyms and Red, then talking to Oak) and 1 Hoenn starter (by getting a PKMN from Oak then going to the PKMN Fan club in Kanto, then a guy named Steven will tell you that Latias or Latios is roaming the game, then you go to Silph Co. and he is there. Talk to him, he asks which stone you want (red, blue, or green) and will give you 1 Hoenn starter with the respective color), you only need to transfer 4 times.
But based on your main question, it is impossible to get all of the Hoenn and Kanto starters in game.
Answer: You would have to play through the game to where someone (could be steven, not sure) gives you the choice of either red orb blue orb or green orb, choose one, evacuate all your beloved pokemon to another game (HG/SS, Diamond, Pearl, Platinum), restart, and repeat. That is the only way i know of to get all 3 starters (Johto Kanto and Hoenn). I personally have Typhlosion, Meganium, Feraligator, Charizard, Venusaur, Blastoise, Swampert, and Blazekin. I have action replay, so i stole Red's blastoise, restarted once, obtained meganium via GTS. Sadly, Treeko is the only one i need.
Answer: Once you beat Red, you can talk to Steven in the Silph company to grab a Hoenn starter, and Oak to get a Kanto. There are only 2 ways to get all starters. You must either migrate them from another game, like Diamond, Pearl, and other previous games. The second option would be to have 2 DS's, and 2 games. On one of them, simply start the game and pick which starter you want. Once you have the ability to trade, you put the DS's together, and can trade them to the game you want, such as creating a new heartgold game, and entering the trade room in the Center, and trading them over.
Comment: The question and comments specify no trading, though the question could be more explicit.
Answer: What you can do is have 2 of you friend breed their starter(If they each choose a different starter) 2x each. Then you can trade the eggs I think and hatch each starter.
Answer: My guess is to try to do the same in the beginning of the game.  Choose a starter Pokemon, then restart the game to get all Pokemon.  You need two Nintendo DS games, either Soul Silver or Heart Gold.  It doesn't matter, but don't save; just restart.  I don't know if this works because I'm trying to do it myself.
Comment: That won't get you kanto starters
Answer: It is possible to get the Hoenn starters. All you need to do is beat the elite four and get all of the kanto badges, then go to Silph Tower. A guy will give you one of the starters; you have to pick either a green, red or blue stone.

the green stone will give you a Treecko
the red stone will give you a Torchic
the blue stone will give you a Mudkip


How to play a long sustained note on an electric guitar?

Question: I've seen such effects on Santana, Robert Fripp and Steve Hackett. They produce a clean sustained sound and I don't know how to create it.
Comment: I use an Ibanez Tubescreamer TS808, Marshall Jackhammer, MXR Super Comp and a vintage 1960's Ibanez compressor CP830. I usually find the sweet spot on stage where sustain is found or at least feedback.
Answer: I know both Steve Hackett and Robert Fripp. I have interviewed them for articles I published in guitar magazines.
You are asking about an unusual effect that requires special equipment.
To get the sounds you described, early in their careers, Steve Hacket used the hand-held electro-magnetic bowing device called the EBow. Later on they used the Fernandes Sustainer installed in their guitars.
The Fernandes Sustainer is not really a pickup at all. It sits in a pickup cavity on the guitar, but it is a device that creates an alternating magnetic field that causes the strings to vibrate continuously as if it were being bowed by a violin bow. It can be used to create completely clean "infinite sustain" sounds, including chords, that are very different in character than what you get with a compressor pedal or with distortion or amp feedback. As long as you hold a note or chord, it never dies out or decays (as long as the batteries are working).
Today, both Hackett and Fripp will only perform with electric guitars with a Fernandes Sustainer installed. Furthermore their guitars have Floyd Rose-type tremolo bridges and not a hard-tail bridge.
Here is a link to Robert Fripp's signature model of guitar, from his luthier, Crimson Guitars. It comes with a Fernandes Sustainer.
Here is a link to Steve Hackett's own description of his guitar collection. The guitars he performs with today all have a Fernandes Sustainer.
Similarly, Adrian Belew's signature Parker guitar uses a Sustainiac, a variant on the Fernandes Sustainer. (and I know Adrian, too). Again, it has a tremolo bridge and not a hard-tail bridge.
Four years ago an entirely new system came on the market: the Moog Guitar. It is much more sophisticated in its ability to create clean sustaining sounds than either the EBow or the Fernandes Sustainer. Check the link for demo videos and recordings from Moog.
You can buy a relatively inexpensive Fernandes guitar with a Sustainer already installed, or you can purchase a Sustainer kit and have it retrofitted to an existing guitar. However, you will need to route out the body to make room for the extra components and batteries that the Sustainer system requires.
Neal Schon, Steve Vai, and The Edge are also Fernandes Sustainer endorsers.
Comment: great answer, just one thing to add, you cant talk about the fernandes sustainer without talking about matt bellamy from muse, he has the sustainer on at all times and that is part of what makes the sound of muse so full even when only 3 instruments are being played
Comment: Santana doesn't use a sustainer and Fripp doesn't use one all the time either. For the solo on Bowie's heroes Fripp would have tape on the stage with note names on them to know where to stand to get each note to sustain naturally via feedback.
Comment: Yes, that was true back in the day with Bowie, but Fripp has had a Sustainer in every guitar that he has played for the last twenty years or more, and it is featured on the many albums he has recorded in that time.
Answer: One easy way: Use a sustain effect processor (Glossary of Guitar Effects).
A sustain effect just saves the highest volume you played and raises the volume gradually as the tone from the guitar decays, thus effectively sustaining the volume at an equal level or at least a slowly decaying level in the dry channel.
Other Tips:

Use a good guitar. Bad guitars often have bad sustain. The neck has to be very stiff. The saddle, the bridge and link between body and neck must be of good quality. The quality and youth of the strings is also important.
Use a genuine electric guitar, not an acoustic guitar with a pickup.
Be sure to press the string good enough. Don't put your finger on the vibrating part of the string, but left from it.
Don't play too loud. Loud tones decay faster, due to anharmonicities.
Comment: A sustain effects processor is adequate to get the Carlos Santana sound but is not at all what is needed to get the Steve Hackett and Robert Fripp sound. See my answer below.
Answer: First off we should understand that the nature of a plucked string is to decay exponentially.
Therefore, sustain on a guitar string is literally impossible without some sort of electronic enhancement.
Before I suggest any of a number of ways to create sustain, let's examine the contributing factors that allow some guitars (electric or non-electric) to appear to take longer to decay (appear to sustain longer).

Bolt on neck vs. set neck. Given two guitar bodies of the same design but one with a bolt on neck and the other with a set neck, the set neck will have a longer period of decay. This is because of the ability of a set neck to transmit sound waves better than a bolt on neck.
Hard tail bridge vs. tremolo bridge. Given two Fender Stratocasters, one with a the standard Fender tremolo bridge and the other with a hard tail bridge, the hard tail bridge will have a longer period of decay for the same reason as above.
The more mass at the headstock is another known contributing factor to create a longer decay.
The type of wood used in the guitar body construction is another factor. Hard woods will allow for a longer decay time than softer woods, e.g. Mahogany vs. basswood. This is because sound waves will travel faster as the density of wood increases which allows for better wave transmission. NOTE: most electric guitars may use many types of wood in their construction. Consider a Les Paul with a mahogany body, and a maple top, and an ebony fingerboard.
Heavier gauge strings will decay slower than light gauge strings as mass plays important role on wave transmission as well.
The nut and bridge material is also a factor. Again the density of the materials is significant. Consider the better wave transmission of graphite saddles vs. nickle.

In summary, the assorted materials that compose the guitar build are the most significant factors in creating longer decay times. One should consider everything from the string itself vibrating and transmitting through the nut and bridge to the neck and body.
Generally speaking a PRS guitar like the one Carlos Santana uses is optimized for his long 'sustained' notes, but that's only half the story, you should also see what pedals and tube amp he is using too.
Beyond the acoustic factors listed above, we should now examine the pick ups and the amplifier. There are a zillion pick ups out there, both single and dual coil (aka humbuckers) pickups will vary on how the sound is transmitted to the amp and this will have an apparent influence on the decay time. The settings on the amp and the amp build may have an influence as well. Foot pedals aimed at increasing gain and compression are factors too. Consider SRV playing a Strat through a tube screamer then into a vintage Fender Super Reverb with optimal NOS tubes, and a mix of AlNiCo and Ceramic speaker magnets. Plenty of sustain.
Let's not confuse sustain with tone, often pros will trade off one for the other as they journey their 'tone quest'.
Aside from using a "sustain effect processor" one could use any of the following to create sustain:

Ebow
Old school controlled amp sustained feedback (example Youtube video)
Use a real bow on a guitar with violin strings and an arched bridge.
Post production using a DAW. Record your piece, copy and splice the waves on and on together.
Loop the sound in an effects box.

Here's a website that discusses real vs fake sustain.
Comment: Yes, there's materials and design decisions that make, for example, the Les Paul sustain better than a Stratocaster, but there are things you can do to improve your sustain. There are two unmentioned tricks I can think of to improve your guitar's sustain. First is raising action, and the second is, when you have the strings on and tuned up to standard, loosen the neck bolts, one turn each, then re-tighten. This will pull the neck tighter to your body.
Answer: There's lots of good stuff above, but that isn't all of it. Yes, many big names use the Sustainer and equivalent, and while I don't own a guitar like that, I heartily endorse the idea, but Carlos, Steve and Robert built their reputation well before it existed.
There are two things that happen when you turn up the amp. First, you get "natural compression" and the second is feedback. If the sound off the amp feeds into the guitar, you as the guitarist are no longer starting the sound but controlling it. If you're not feeding back, you still get the compression effect. There's also stomp boxes that give you that, and there exists a question to explain them.
Answer: Adding to the fantastic answers so far
The Acoustic Synthesizer:
As a fairly new development, Paul Vo(the inventer of the Moog synthesiser) has been working on an addon for acoustic guitars which works like a sustainer, and can be used to manipulate the waveforms produced by the guitar.  It sounds pretty trippy! here's their kickstarter
True Temprament:
There's another technology that I don't think's been mentioned.  True Temprament frets are a company that will re-fret your instrument so that it's more accurately in tune Intonation-wise right down to the last hz.  This allows the notes to be more resonant with each other and thus, increase sustain :)
On Robert Fripp:
Adding to what Wheat was saying about Robert Fripp, I unfortunately do not know him :(, but if you have Spotify there's a massive collection of interviews and after-show questions that he's done where he will occasionally talk about the equipment he uses, and this website lists all the gear, however further investigation is needed into what does what!
Santana/PRS:
As for Santana, I know that PRS guitars (as used by Carlos Santana) have an extremely good reputation for having a resonant, rich, sustained sound. One of my favourite bands Opeth have been using PRSes for years, here are some examples.
Using/Abusing feedback/harmonics:
There's a trick that Joe Satriani and Gary Moore have both used in order to get a sustained harmonic from their guitar, though slightly different.  Gary moore setup his amp sound such that a certain note created a resonant frequency with the sound of the amp so that once he'd held the note, the feedback would sustain it enough that it didn't deafen, but also didn't fade.  Those of you that know Gary Moore, know the note I mean!
Joe Satriani uses a similar trick.  He lets the feedback create a note with his guitar, and then will move around the room until he finds another harmonic which resonates with the frequency, and this causes the note to change, while still sustaining.
The two linked videos on their names will make this much clearer!
Here are a few videos that sprang to mind from the tech that's been mentioned already.
Fernandez sustainer
True Temprament
Hope that helps add something :)
Answer: One way to give the illusion of a sustained note is to repick the note at a time where the pick attack will be disguised by something else going on in the music such as a snare hit or chord strum. Just make sure you don't pick so hard that you get twang or so the note comes back noticeably louser than it was before.
Answer: "u" out the nut and bridge string rests, as most are "V" shaped"
use graphite (pencil lead powder) as well.
use proper guaged strings for your guitar. (no they are not" one size fits all."
use vibrato, as violinists do.
Just a few things not mentioned above.
" ah, careful with that there file Elroy !"
Answer: Santana, David Gilmour, and Fripp all used fuzz pedals (like the Big Muff), which act as a sort of compressor/sustainer, especially when played really loudly :)
Answer: One thing I've missed with the "feedback" proposals is the difference between acoustic and magnetic feedback.  Acoustic feedback works by feeding back sound to the string.  That's what you want here.  Magnetic feedback goes straight from the speaker to the pickup.  That's not what you want for this effect.
Double-coil pickups are less sensitive to magnetic feedback.
Answer: What I use for infinite sustain is an Electro Harmonix Super Ego pedal with the speed (attack) cranked to the left and the sustain cranked to the right.
Answer: For recordings that require guitar solos, the simplest trick is to record at a higher pitch and speed and then slow the recording down; you get very clean sustained notes that way.


What is the sack-to-ship ratio?

Question: In the world I'm building, the day lasts 9 of their years. This means that they are almost always on the move, living in blimp-like cities and houses. I've been designing these and I am having trouble with the exact ratio for the balloon size to the size of the cargo. What is the sack-to-ship ratio? Weight ratios will work as well.
Answer: The net lift for the gases is how much the volume of air they displace weighs, minus the weight of the lifting gas itself. The following values are from this site and are per 1,000 cubic feet of volume.
<code>         | Weight of Lifting Gas |  Weight of Air |  Net Lift
         +-----------------------+----------------+------------
Hydrogen |  5.31 lbs             |  76.36 lbs     |  71.05 lbs
Helium   |  10.54 lbs            |  76.36 lbs     |  65.82 lbs
</code>
So, if you have 71 lbs of cargo, you need 1,000 cubic feet of hydrogen to lift it. The volume which the cargo takes up is irrelevant.
You'll need more than to just lift cargo, of course, you have to lift the rest of the ship including the gas bag, deck, rigging, etc.
This is assuming the atmosphere is the same density as on Earth. The specific values are with respect to Earth's gravity, but the ratio will remain for any (reasonable) value of gravity.
If your planet isn't populated exclusively by Americans, Myanmas, or Liberians then they probably use the glorious metric system.
In which case the table looks more like this for a volume of one cubic meter:
<code>         | Weight of Lifting Gas |  Weight of Air |  Net Lift
         +-----------------------+----------------+------------
Hydrogen |  0.090 kg             |  1.292 kg      |  1.202 kg
Helium   |  0.178 kg             |  1.292 kg      |  1.114 kg
</code>
If you got some cargo from a backward country and they said it weighed 71 lbs, once you properly weighed it at 32.2 kgs you would know you need about 26.8 cubic meters of helium to lift it.
In your specific case, if you wanted to lift a typical mobile home weighing 6758.53 kilograms (14,900 lbs):
$$6\,758.53\ \mathrm{kg} \times {{1\ \mathrm{m^3}} \over {1.114\ \mathrm{kg}}} \approx 6\,070\ \mathrm{m^3}  $$
You'd need 6,070 cubic meters (~214,000 cubic feet) of hydrogen. This is about two and a half Olympic swimming pools in volume. Or, more specifically, a sphere 22.6 meters (~74 ft) in diameter (a bit over 8 stories tall).
Comment: @Jim2B Helium certainly is and [it's getting worse](http://news.psu.edu/story/274153/2013/04/22/earth-and-environment/probing-question-are-we-running-out-helium). But, they can make large volumes of gaseous hydrogen with water electrolysis. Of course, there is that *boom* factor there...
Comment: Don't forget that these gases are *rare* in terrestrial planet atmospheres.  Since ownership of the gas = survival, this could be a source for quite a bit of drama.  It also means these gas bags could be by far the most valuable thing on the planet to its inhabitants.
Comment: it is, a good ship is very valuable. Also think of how one madman could blow up an entire city
Comment: You would probably want to increase the gas bag diameter by something on the order of 30%, assuming the gas bag and rigging weigh about as much as the trailer.
Comment: could you add the actual equation for figuring this out
Comment: @majornorwal The actual equation? I included my equations. Which are you talking about?
Comment: for the motor home
Comment: @majornorwal That is the equation I already included. You multiply the weight of the motorhome by the cubic meters per net lift of the gas and out comes the total volume of gas required to lift that much mass.
Comment: last question. how do you figure out the net lift of the gas
Comment: @majornorwal Sentence number one: "The net lift for the gases is how much the volume of air they displace weighs, minus the weight of the lifting gas itself."
Comment: now i feel stupid
Comment: Man, they're going to run out of hydrogen.  Leakage losses are non-trivial.
Answer: If you want to forego the use of lifting gas, and don't mind going big, look at Buckminister Fuller's "Cloud 9"
Fuller's insight was the volume of enclosed air in a geodesic dome increased by the cube/square law; it increased by the power of 3 as the dome doubled in area. At some point the amount of air inside the dome vastly outweighed the dome itself, and a temperature differential of as little as 1 degree f could cause the dome to take off like a hot air balloon.

A 100-foot-diameter, tensegrity-trussed, geodesic sphere weighing three tons encloses seven tons of air. The air-to-structural-weight ratio is two to one. When we double the size so that the geodesic sphere is 200 feet in diameter, the weight of the structure increases to seven tons while the weight of the air increase to fifty-six tons – the air-to-structure ratio changes as eight to one. When we double the size again to a 400-foot geodesic sphere – the size of several geodesic domes now operating – the weight of the air inside increases to about 500 tons while the weight of the structure increases to fifteen tons. The air-weight-to-structure-weight ratio is now thirty-three to one. When we get to geodesic sphere one-half mile in diameter, the weight of the structure itself becomes of relatively negligible magnitude, for the ratio is approximately a thousand to one.

Even larger domes work better, since you have a huge "reserve" of lifting power so long as the interior of the dome is warmer than the outside air. The waste heat of human activity and machinery inside the dome will actually help keep it aloft at night.
Like any hot air balloon, you are adrift in the wind (you could add engines and propellers like a Dirigible airship), and the balloon will work better in cold climates where the temperature differential is more pronounced.
The main issue here is are your people technologically capable of creating and maintaining such a structure? Once the idea of a geodesic or similar lightweight structure is developed, it should not take too long for someone to make the same deductions that Fuller did.
Comment: But the dome materials must be stronger as the dome gets bigger.
Comment: The beauty of a geodesic dome of this nature is much of the strength can be from tension members, which are far lighter than compression members. Much of the domes strength could be found in a cable net "pulling" against the forces of the expanding gasses within.
Comment: While I do agree the bottom half is compression that doesn't change the fact that it's still subject to the square-cube law.  You can't just scale it up with the same strength!
Comment: The entire Fuller "Cloud 9" is a sphere (two geodesic domes joined at the base, if you will), so the entire structure will be in tension, which was Fuller's point in this thought exercise. Since the temperature differentials needed for flight could be as little as 1 degree farenhight, the amount of stress will be rather minimal as well. Cloud 9 structures could have been built in the 1960's, using then available technology, using modern materials like carbon fibre would make this much easier today.
Comment: If it's purely in tension then rope is a reasonable model--but what's going to happen if you make a dome out of rope???  If it's a lighter-than-air craft I think you can get away with the only compression element being a hoop around the middle, though.
Comment: Another thought on this:  Since we are talking about a very weak lifting gas there's another possible option:  Nitrogen.  It's easy to refine out of the atmosphere so you can replace what leaks out as you go.  (Home "oxygen" generators for medical use are really nitrogen generators with the waste being sent to the patient and the nitrogen being thrown away.)

What is the sack-to-ship ratio?


Why is max power time limited for jet/piston engines?

Question: Usually max power is time limited for jet/piston engines to 10 or 5 minutes. Can anybody explain the reason? What will happen if those limits are exceeded?
Answer: Maybe Nothing....
Maybe Catastrophic Failure...
Any number published by an engine maker (or any aviation part maker for that matter) is the numbers they have tested it to. Thus if Continental or GE claims a 2000 hour TBO but puts a 5 minute limit on max power, that in turn means that the 2000TBO number is based on operations within these published limitations. Exceeding these limitations may cause TBO to arrive sooner than expected and could possibly cause undesired operating characteristics. It is of course possible that if you drive the engine at max power for a time greater than suggested, it will throw itself to pieces. However, this is unlikely.
In some cases there are physical limits based on the materials used in the engine. If exceeding maximum run time provides a way to generate internal temperatures that exceed the limits of an internal part you could very well have an issue very quickly. From my experience with piston engines it's generally a wear and heat fatigue issue when flogging the engine at max power. That being said if the POH calls for a maximum of 5 minutes at full power and you spend 5 minutes and 30 seconds at full power on a climb out chances are you will be fine. If you do this routinely you may find that your engine hits TBO long before the published numbers.
This article also alludes to the fact that there may be other limiting factors such as the strength of the gear box the engine is connected to.

The shp of a turboprop engine is restricted by the strength of the gearbox that drives the propeller, and by the ability of the airplane to handle the thrust developed by the prop.

On any note I would think that most manufacturers publish numbers that are on the conservative side for many reasons.
Since this question is highly related to TBO number you should check out this article about some common myths around engine overhauling numbers and engine wear in general.
Definitions:
TBO: Time Between Overhaul. This is generally the lifetime of an engine. Although some people commonly think this is a legal number it is only manufacturer suggestion and you are free to exceed it (and plenty of people do).
POH: Pilots Operating Handbook. The document that outlines the limits and safe operation of a given airframe.
Comment: I suspect that somebody who needs to ask this question will also need to have abbreviations such as TBO and POH expanded for them.
Answer: I suspect that the answer might vary from aircraft to aircraft and engine to engine, so I'll answer specifically for an aircraft/engine combination I am familiar with.
The Lycoming O-360, of various models, was chosen by Robinson to power the R22 series.  This engine is widely used in fixed wing and rotaries, is more or less bullet proof when cared for properly and is serviced by a market with a good spares supply and availability of skilled mechanics and overhaul centres.
For the R22 Beta II, the engine is capable of producing 180 HP but Robinson said  we only need 130 HP, maybe 140 HP at most but can you make it lighter?  I forget the numbers - they came from an interview with  Frank Robinson, I'm sure Google will lead you to accurate ones.
Lycoming responded by making several changes without changing the major replaceable components including thinning the cylinder walls and making the cooling fins somewhat smaller.  This means that the engine is less capable of dispersing heat and consequently, cannot run at maximum power for long.
Eventually, they certified it at 145 HP (less than the maximum - i.e. "derated").  The POH (Pilots Operating Handbook) allows using the maximum derated power, 145 HP, for short periods, from memory, 5 minutes.  The engine life and reliability are only good if these limits are not exceeded.
There are also limits on how much power the drive train, including the gearbox, tail rotor drive shaft and tail rotor gearbox, can handle which place limits on the maximum power the engine can safely produce.
In an emergency, it is possible at sea level to exceed the 145 derated maximum since there is no physical device to stop you putting the collective into your armpit or opening the throttle wide but there is a good chance that doing so will damage the drive train or blades and if exceeded, a maintenance inspection is mandatory.  Using the whole 180 HP will lead to damage and has been implicated in accidents.
Answer: For gas turbine engines, the three measurements to watch are:
MTO: Maximum TakeOff thrust. (no more than 5 minutes)
MCT: Maximum Continuous Thrust. (okay, unless the turbine overspeeds or overheats)
MCL: Maximum CLimb thrust. (often the same as MCT)
Those three limits are the ones established by the engine manufacturer during extended lifecycle testing as sustainable while maintaining the engine's established time between overhaul. Exceed them, and the aircraft maintenance person must consider a shortened TBO if they don't want to risk an in flight failure.
And, yes, the manufacturer used up a pile of engines establishing those limits.
On piston engines, heat is the big enemy. Exceeding RPM isn't usually a concern, as most props become inefficient when the blades go supersonic, so overspeeding a piston engine is counterproductive. Overheated parts become weaker, and wear faster even if they don't break immediately. In particular the cylinder heads (and gaskets) will likely be the first to fail in an overheat situation.
Why is it possible to exceed those limits on aircraft engines? In his book Fate Is The Hunter, Ernest Gann describes it most eloquently, when talking about backfiring the engines on a DC2 to clear off ice that was closing the air intakes to the engines, causing them to lose power: This is terrible abuse of the engines, but not as bad as asking them to fly through a mountain. (anyone who holds a pilot's license should read that chapter on the icing incident... it's scary)
Unlimited overboost is there in case of dire emergency, when the choice may be either overhaul the engines prematurely, or crash the plane.


Select only one side of a text frame in InDesign CS6

Question: I am designing a fillable form in InDesign CS6 (Mac) and want to add a border to only the bottom of certain text frames. My question is: how do I select only one side of a text frame?
Answer: With the white arrow – the direct selection tool – you can select the bottom vertexes of your rectangle; but that won't do you any good. The border of a frame in InDesign is applied to the entire frame, not on a per-selection basis (just like in Illustrator).
Some other options:

Put your text inside a one-cell table. Each of a cell's borders can have a setting of its own.
Set a Rule Below for the last paragraph in this frame.
Draw a line manually, and either leave it placed on your page (so it will not move vertically when you add or remove text), or cut it and paste as an anchored object on the last text line (and then it will move along with the text).

Since a fillable form needs to be of a fixed size anyway, I'd simply draw a horizontal line just below it.
Comment: I second the one-cell table. ID's tables are remarkably good for layout purposes.
Comment: I chose to use option #3, mostly because it was most familiar to me. I will look into the one-cell table option later as time permits.  Many, many thanks!
Answer: Object → Effects → Inner Shadow → Mode: normal, X Offset: 0, Size: 0; Y offset: border width.
Comment: Just tried exactly this on a text object in ID / CS5.5 and it didn't work for me. Ended up drawing a line.
Comment: I tried this for a vertical ruler on the left side. This does seem to work on-screen, but printers (including pdf printers) may leave a very thin line in the shadow colour on the top and / or the bottom of the object.


How to buy an Indian railways add-on ticket for a child?

Question: I bought confirmed tickets for us online. After, we decided to take friend's child with us, age 6. Is it possible to buy a ticket for him on same PNR or do we need new one; a seat isn't necessary.
Comment: I don't think it is possible to do so online. Infact you cannot even book a ticket if a child below 12 is the sole traveller and you have not opted for berth (50% fare). Your best bet would be to take a printout of electronic reservation slip to nearest booking office and ask them.
Answer: Nope. You have to buy a separate ticket for the same. Once a PNR is generated, you cant add people, but can cancel the passengers.


after clicking on add paint slot, Blender still reports missing texture slots

Question: I am trying to texture paint my object in Blender 2.74 blender-render mode. However, I have noticed that when using a node material, I loose the ability to add new paint slots in material mode. In addition, I keep receiving the message "missing texture slots". Also, clicking on add new paint slot does not resolve the issue, but in other cases this usually solves the problem. After clicking on add new paint slot, Blender does add the new texture in the textures property window, and I can even click on any of those textures in the texture properties window, but it does not activate the texture brush tool and keeps on throwing this error.
Now this only happens when I activate a material slot and click on use node in the node editor. In conclusion, I am thinking that it is not possible to texture paint on a node material. Is this so, or is there a way to fix this problem?
Comment: Haven't tried but expect your guess is right, node based materials in BI have limited support so would be the cause of the issue. Try a using non-node material to do the painting.
Answer: It is not possible to paint on a node based material in Blender Render. You can paint on a material in Cycles as nodes as long as you have set up an image node and texture image to paint to - and the best interaction there is in Material Draw mode so that you can see the layers of image textures together.


Can I damage condenser mic with Phantom Power connected using unbalanced cable?

Question: I have Chord CM05 condenser microphone. For the first trials I bought cheap Phantom Power Supply, like this one:

Unfortunately the XLR cable I used was unbalanced one (with pins 1&3 interconnected). That means 48V occured only on pin 2, pin 3 had 0V, I figured it within one minute or so. Could it damage the mic?
Later, when I got correct balanced XLR cable and connected it, I hear only noise on the output when power is turned on and nothing when turned off.
I verified that there is approx 48V on both 2 and 3 related to pin 1.
I have unbalanced recording device behind the power supply, but it should be no issue, since power supply has blocking condensers on both signal lines (I checked it by multimeter, that DC current can't flow through.
I have no other condenser mic, but when I connect dynamic mic, sound passes through.
For now, I don't know if mic is damaged (or possibly was already defective before) or it is incompatible with this phantom power supply. Unfortunately I can't check it elsewhere.
Answer: The Mic can handle the phantom power, so you won't damage it by giving it phantom power. The only thing that might happen is the phantom power won't GET TO the Mic.
Pretty benign but annoying problem.


WebDAV in Windows Explorer: Problems if port is not 80?

Question: I want to connect to an OwnCloud WebDAV drive. I tried
<code>\\IP:25000\owncloud
</code>
and get asked for my credentials. But usually it doesn't accept my username and password despite the pair is entered correctly.
But - and that is strange - sometimes it works (oh really!). But even then it's crippling slow despite a fast server and connection.
For me it seems Windows Explorer has a Problem that my server cannot use port 80 for WebDAV. Is that true?
Answer: Try this format:
<code>\\IP@25000\owncloud
</code>


Translating 'creative by nature' / 'naturally creative' into latin

Question: I would like to know the meaning of 'creative by nature' or 'naturally creative' in latin. According to google translater it is 'natura partum', but when translated back into english it means something else.
Answer: I believe that the confusion here stems from algorithms and double meanings. The Google Translate algorithm doesn't understand the role of 'creative' in the sentence, so it substitutes partum, from the verb pario, which means "bear, or give birth to, to create." When you put it into the algorithm again, this word's first two meanings are used, leading to natural delivery.
The correct translation here would be naturaliter artifex, from naturalis ("natural") + -iter (adverbial ending) and artifex ("artful, creative").
Comment: @cnread I notice that's true, but [it still seems](https://www.latin-is-simple.com/en/vocabulary/adjective/1145/) to have more to do with ability rather than creativity.
Comment: Though _artifex_ means "artist, creator" or "master, expert".
Comment: @VincenzoOliva. According to Oxford Latin Dictionary, it's also commonly used as an adjective.
Answer: "By nature" may be translated either with the ablative of cause naturā or with (what appears to be) the agent complement a natura. We find the latter in Cicero's Brutus:

T. Torquatus T. f. et doctus vir ex Rhodia disciplina Molonis et a natura ad dicendum satis solutus atque expeditus [...]
"Titus Torquatus, son of Titus, who was taught by Molo in Rhodes and by nature gifted with decent effortlessness and ease in speaking" [...]

The ablative of cause is attested in Seneca the Younger's De ira, Liber III:

Omnes sensus perducendi sunt ad firmitatem; naturā patientes sunt [...]
"All senses must be directed to firmness; they are enduring by nature" [...]

I couldn't find a single word suitable enough for "creative". "Creativity" itself doesn't have a perfect analogue (imaginatio comes close).
However  we may use a construction similar to what we see in Cicero: ad inveniendum expeditus. We may specifically translate it as "full of inventive", so "creative". More literally, it indicates "ease in inventing, imagining".
In conclusion, two possible translations are Ad inveniendum naturā expĕdītus and A natura ad inveniendum expĕdītus. I personally prefer the former, I would choose the latter if the qualities were more than one (like in Cicero's case).
Answer: The adjective praeditus is often used to speak of one's 'natural gifts' or endowments: courage, criminality, wisdom, eloquence, self-control, talent, and so on – even limbs.
It's paired with some noun to denote the thing with which one is endowed. That noun is typically modified by its own adjective. Apuleius, Lucretius, and Cicero are especially fond of this word.
In Lucretius's De rerum natura, a phrase that recurs several times is 'endowed with such-and-such a nature.' The phrase is used to describe the way something naturally/intrinsically is – for example, in book 1, line 236:

inmortali sunt natura praedita certe,
  'certainly, they are endowed with an immortal nature'

The question is, which adjective should be used to make Lucretius's phrase mean 'endowed with a creative nature'? As Vincenzo Oliva has noted in his answer, there isn't really a classical Latin word for 'creative' in our modern sense.
I'll make three suggestions. Ultimately, it's down to you to choose the one that best captures your own conception of the word 'creative' and that best suits what you intend to use the phrase for.

Sollers: The Oxford Latin dictionary defines this adjective as 'full of devices or expedients, clever, skilled, ingenious, resourceful.' Although 'skilled' is in that list of definitions, the other definitions suggest that the word goes beyond mere physical abilities, to the way that those abilities are exercised.
Sollers and related words can be used to describe ingeniousness or cleverness ('creativity') in various practices (e.g., speaking, warfare, or architecture) and also in the plastic and performing arts – for example:

Horace, Ars poetica 407:

Musa lyrae sollers
  'the Muse skilled/ingenious at the lyre'

Horace, Carmina 4.8.7-8:

hic saxo, liquidis ille coloribus / sollers nunc hominem ponere, nunc deum
  'the latter man (Scopas) skilled/ingenious at depicting now a human, now a god in stone, the former (Parrhasius) at depicting them in liquid colors'

In this case, the phrase would be sollertī nātūrā praeditus, 'endowed with an ingenious nature.'
Artifex: This noun/adjective was used in user12390879's answer. Among its meanings are 'A craftsman in one of the fine arts, a sculptor, painter or the like, an artist'; 'An actor, musician or dancer (on the stage or elsewhere), and artist, performer'; and 'A maker, creator, producer; the author (of a book).'
The advantages of this word are that it's strongly linked to the plastic and performing arts, and the word 'art' is clearly recognizable in it. Both these facts may be significant if you're thinking specifically in terms of artistic creativity.
In this case, the phrase would be artificī nātūrā praeditus, 'endowed with an artistic nature.'
Inventrix: This was inspired by Vincenzo Oliva's answer, though it involves a bit of license, because the feminine noun inventrix is being used as a feminine adjective. Still, such a thing is done often enough in Latin literature that I feel comfortable suggesting it. The noun is based on a verb that has among its meanings 'To devise, contrive, plan'; and 'To devise for the first time, originate, discover, invent.' It's a fairly general sort of creativity.
Of course, the advantage of inventrix is that the word 'invent' is clearly recognizable in it.
In this case, the phrase would be inventricī nātūrā praeditus, 'endowed with an inventive nature.'

Note that, in all three versions, if the phrase is describing a female specifically, you would replace praeditus with praedita; for a group of males only, or a mixed group of males and females, you'd use praeditī; and for a group of females exclusively, you'd use praeditae.


Mindfulness of Breathing, Mindfulness with Breathing

Question: I saw a comment in another post suggesting that these are two different things. Can anyone explain or refute?
Answer: Mindfulness ('sati') means 'to remember'. The breathing as a meditation object cannot be 'remembered'. Instead the breathing is observed, which is called 'anupassi'.
The purpose of 'mindfulness' in Buddhism is 'to remember' to keep the mind in a state of right view & right intention (refer to MN 117) or 'to remember' to keep the mind free from covetousness & distress (refer to MN 118; MN 10; etc).
Therefore, to practise 'mindfulness of breathing' is an impossibility because mindfulness (sati) means to remember rather than to observe (anupassi).
Instead, the practise is 'mindfulness with breathing', which means to remember to keep the mind free in right view free from craving, as instructed in the four noble truths. When this is properly done, awareness/observation of breathing will naturally arise due to the quiet & silence of the mind.
Thus, mindfulness with breathing is remembering to keep the mind free from craving with awareness of breathing arising automatically/non-volitionally as the 'sign' of this right mindfulness.
Those that try to practice mindfulness of breathing rarely progress because the mind must let go of craving to progress; which includes letting go of the craving or intention to watch the breathing.
Ideas about 'mindfulness of breathing' are yogic or Hindu meditation.
'Mindfulness with breathing' is Buddhist meditation.
Comment: Thanks, so why do we hear so much emphasis on the breathing, in-out, long-short, start-finish?
Comment: @m2015 That would be appropriate to post as a new/separate question (instead of as a comment).
Answer: Mindfulness is often mentioned within the scope of maintaining ethical behaviour in the actions of body, speech, and mind. However, many people conflate 'Mindfulness' with 'Vipassana'.
Mindfulness of mental activity is by far the most challenging, and likewise the most important.
Monitoring the breath is a good way of calming excessive internal chatter. Once you have the simple ability to monitor the breath, switch to monitoring the mind.
The effort you use in your meditation is: a mode of joy in having the opportunity to practice, the determination to practice, and faith in your ability to practice.
I believe that vipassana arises out of mindfulness: as we monitor our minds we begin to perceive the nature of mind - not through thinking about it, but from experiencing how it shapes our world.  @Dhammadhatu or others may be able to point to text that support (or lay waste) to such an idea.


Pre Cumulative update process

Question: Guys this is the first time im installing a sp2010 CU.  I would like to know what i need to do before applying this update to our servers.  Specifically what do i need to backup before i apply and any other steps.
Answer: Microsoft recommends you backup and document the entire environment:
Technet
I'm guessing you were after a more "personal experience" kind of information but I thought I'd put the link here in case you hadn't read it.

Pre Cumulative update process


Can anyone identify this glassware?

Question: Hoping for a little help identifying this lab glass , I don't know anything about lab glass , this was in a storage unit I'm purchased at auction,,, there is what I think is called a condense & 2 round beakers or flasks,, one is 50ml & the other is 200ml ,,, all the male & female connector are marked SJ GSA CO 28/15 ...PLEASE is there anything you can tell me about what there are called & what they would be used for.
Answer: The glassware isn't particularly valuable. Finding someone who wants it will be the problem. If you were going to buy it new, I'm thinking maybe $150.
It is indeed a distillation setup. The large flask is the pot in which you'd put the stuff that you wanted to boil. The small flask would collect the stuff that you boil off. The nipples on the condenser are for rubber hoses to connect to a water supply so that the condenser jacket can be water cooled. Water goes in on the bottom and out on the top. In order to use this you're missing some parts.

You need a couple of ringstands and clamps to hold the whole thing together.
Two thermometers would go into the top of the condenser. One to monitor the pot temp, and the other to monitor the condensate temp.
You need some metal clamps to hold the flasks to the condenser.
You need something to heat the pot, a Bunsen burner would do.
Comment: Not looking to use it , As I said it was in a storage unit
I purchased at auction , I buy to sell everything in the unit. Was just interested in finding out what it is so I know how what to call it when I try to sell it
Answer: Careful - You are missing a distillation adapter between the condenser and the receiving flask. Without the adapter, the receiving flask should simply be placed under the end of the condenser to receive the distillate, rather than attached to it. Otherwise you would be heating a closed system, possibly leading to a catastrophic failure.
Comment: Good point that I failed to mention. It looked to me as if the thermometer holes are not ground glass. I assumed that there was a pressure exit there, but didn't mention that.
Comment: The joints are reminiscent of the Buchi ones for the receiver flask on a rotary evaporator under vacuum.  Could this be for vacuum distillation?
Comment: Not looking to use it , As I said it was in a storage unit
I purchased at auction , I buy to sell everything in the unit. Was just interested in finding out what it is so I know how what to call it when I try to sell it

Can anyone identify this glassware?


Is there a preferred frame size calculator?

Question: I am buying a new road bike. I have looked online for calculators but I am getting different answers on which frame size I should get. I've got 53 cm on a calculator that only considers inseam height and 56 cm on another one that also considers riders height so I don't know which one is correct because I don't want to end up with a bike that is either too big or too small for me.
Comment: TBH nothing's perfect.  One maker's 56cm frame can end up "smaller" than another maker's 53 cm frame.   So the calculators are a guide at best.  If you're buying on line, do consider a real bike shop first.   Remember, buying a bike is the start of a long relationship with a LBS.
Try your bike before you buy it.
Comment: Any calculator will only ever give you an approximation, you need to try the bike to know for sure.
Comment: This is the wrong question to ask. The question you really want an answer to is "How do I get the correct fit for my bike?"  And that is the question being answered below.
Answer: IMO Frame size is more than just measurements. A proper bike fitting pairs your riding style & level with the frames own handling characteristics. (defined more by tubing and angles than measurement alone)
BUT... not everyone's out to get a custom bike frame made or go research their frames butted tubing or headtube angles... But I always suggest visiting a place where they know how to "fit bikes" (for racing, touring, etc) and getting advice from a bike fitter.
Don't forget to buy a water bottle and power bar while you're there, chances are they don't charge you for the advice. #smallbusiness
Answer: As I have written in another thread, the seat tube length (a.k.a. "frame size") is not the most important measure for how a bicycle fits you. Bicycle fit is mostly about putting the contact points between rider and bike (saddle, handlebars and pedals) into the correct positions with regard to the rider's body.
Where these points should be is a matter of body geometry, riding style and personal preferences - and not an easy question to answer (although there are some general guidelines that work pretty well for many riders). As the starting point should not be the bike but the rider, it is especially hard to answer bike fit questions over the internet without seeing you sit on a bike. Guidance from someone who knows about bicycle fitting is a good investment.
In order to determine if your contact points could be positioned correctly on a certain frame, the measures stack and reach are more important than the seat tube length. Stack is the vertical distance between the bottom bracket and the top of the head tube, and reach is the horizontal distance between these two points. These two measures (plus handlebars, spacers and stem geometry) determine basically where the hands will be in relation to the feet. When these two points are fixed, the saddle can pretty easily be positioned correctly by using an appropriate seat post (length and setback).
tl;dr: Try to find out what stack and reach you need, either by consulting a bike fitter or by measuring a bike that fits you very well. Compare frames by their stack and reach measurements instead of the seat tube length to see if they could fit you.
Answer: I have found that the one from Competitive Cyclist is pretty good: http://www.competitivecyclist.com/Store/catalog/fitCalculatorBike.jsp
It takes into account the lengths of your legs and arms, so prepare for some measuring. Also, if you have no idea what you are looking for, do not buy blind but try the bikes in person.
Comment: Although I did not downvote because this *is* an answer for the question asked, I would guess that the general feeling is that fit calculators are not accurate without a skilled fitter to interpret the data for the specific brand you are looking at. I would never recommend a fit calculator as a primary means of finding the correct size. Once you know enough to use one, you can usually bypass them anyhow. :)
Comment: Thanks. I will try it once i am near a measuring tape or some sort of ruler as the one displayed there.
Comment: Why the downvotes?


How to change account to write reviews for Ubuntu Software Center?

Question: I want to write reviews for applications using another account. In Ubuntu One, it's possible to sign out at will, but I can't do that on the Ubuntu Software Center. How can I change accounts?
Answer: The only way I know is to delete the current password for the Software Center and then sign in again and select the "already have account" and sign in using the other account.
There may be a more elegant way to do this as this is a quick and dirty solution but here it is.
Open the dash and start typing "password" , the application "Passwords and Keys" will come up. When you open the application you will see the following.

If you click on the arrow the password list will open and you will be able to right click on the password for the Software Center.

On the right click menu you will be able to delete this password.  As I said above, you will then need to log in using the password to your other account and will have to repeat the process every time you want to switch between accounts.


Why do games use tick rates in their networking and servers instead of an event system?

Question: Why do most games limit themselves with a tick rate in their networking? Isn't it better to make something like an even system where for example client A does something then the client sends related info to the server, and same for the server when something happens on it it sends a packet to the client, instead of using a tick rate and sending information only at some specific frequency. Is it cheaper/faster to send more data in a single packet or? And the same question goes for server tick rates, some servers limit themselves on specific tick rate frequencies, why do they do that? Why not just make a loop and run each tick after each other instead of having a gap between them or risking one tick to take longer than it should and causing bugs? What's the benefit of the tick rate approach for servers and for networking?
Answer: It's largely a matter of, what's the default assumption for a given segment of time in your game? Is it more likely that...

absolutely nothing happens
something happens

If it's more common that something happens than nothing, a regular server tick is a good way to go. For instance, in a multiplayer shooter game, players can change direction and fire off shots in fractions of a second, so there's stuff happening constantly. It makes sense to send regular, frequent updates to keep everyone appraised of the evolving situation, without excess overhead of trying to sleep through or skip timesteps in which nothing happens, since that's rarely if ever the case.
If it's more likely that nothing happens than something, then an event-based system is a good way to go. Many games with asynchronous multiplayer work this way, where the game state is only updated when one player logs in and takes their turn / actions, then sits idle until the next player needs to act. It might be minutes or hours, even days before the next event that affects a given player occurs, so doing a sub-second tick update throughout that span would be wasteful.
So, it all depends on what kind of game you're making, and what needs your server has to fulfill.
With regard to ensuring a regular tick frequency, for games that use it, I recommend checking out this earlier answer.
Comment: So basically in the games where something happens more often than nothing it would be better for performance to sometimes send empty packets than to sleep through that time? And the time between actions is very small so it woulnd't be effective to sleep through it? That makes sense. But what about server ticks, not the network but the loop in which server processes information, I've seen some servers and they limit their ticks. I guess it's to save on the server cpu. Because it would be running on 100% if there is no sleep.
Comment: There's that aspect, and there's also consistency and fairness. You want the game to play the same way, always, under all load conditions, right? It shouldn't play one way under light load and a different way under heavy load. So setting the tick frequency to a fixed constant helps you ensure it stays the same across a wide range of loads.


Integral inequality on a periodic function

Question: Given $f:\mathbb R\to \mathbb R^+$ continuous and periodic of period $T\geq 0$, I am asked to prove that $$\int_0^T\frac{f(x)}{f(x+\alpha)}\mathrm dx\geq T,\; \forall \alpha\in\mathbb R.$$ How does one tackle this problem? It seems absolutely non trivial to me.
Comment: Nice question (+1)
Answer: Write $f(x):=e^{g(x)}$. Then
$$\int_0^T{f(x)\over f(x+\alpha)}\ dx=T \int_0^T e^{g(x)-g(x+\alpha)}\ {dx\over T}\ ,$$
and the convexity of the exponential function implies that this is
$$\geq T \exp\left(\int_0^T \bigl(g(x)-g(x+\alpha)\bigr)\ {dx\over T}\right) =T e^0=T\ .$$
Answer: Here's a solution that came to my mind.
Firstly, we prove the following (easy) consequence of $g(x) = \frac{f(x)}{f(x+\alpha)}$ having period $T$: $$\int_{0}^{nT} g(x) \ dx = n \int_{0}^{T} g(x) \ dx$$ for any natural number $n$.
It is easy enough to see that we may take $\alpha > 0$ (Replace $\alpha$ by $\alpha +kT$ for some $k \in \mathbb N$). We first handle the case where $\alpha = \frac nm T$ for some positive integers $n,m$. Now, $$\int_{0}^{nT} g(x) \ dx = \sum_{j=0}^{m-1} \int_{\frac jmnT}^{\frac{(j+1)}mnT} g(x) \ dx = \sum_{j=0}^{m-1} \int_{j\alpha}^{(j+1)\alpha} \frac{f(x)}{f(x+\alpha)} \ dx = \sum_{j=0}^{m-1} \int_{0}^{\alpha} \frac{f(x+j\alpha)}{f(x+(j+1)\alpha)} \ dx$$
The left hand side is $\displaystyle  n \int_{0}^{T} g(x) \ dx$ by our initial observation, also, the summation can be brought inside the integral on the right hand side, to get
$$ n \int_{0}^{T} g(x) \ dx = \int_{0}^{\alpha} \sum_{j=0}^{m-1} \frac{f(x+j\alpha)}{f(x+(j+1)\alpha)} \ dx$$
Now, we have the following due to the AM-GM inequality: $$\frac{a_0}{a_1} + \frac{a_1}{a_2} + \cdots + \frac{a_{m-1}}{a_0} \ge m$$ therefore, the term inside the integral is $\ge m$, so the integral itself is $\ge m \alpha = nT$, and so we're done.
Moving on to irrational $T/\alpha$. Then we have the sequence of fractional parts $\{n T/\alpha \}$ is dense in the unit interval $(0,1)$, therefore, we choose arbitrary large $n$ such that $\{ nT/\alpha \} < \epsilon$, for some $\epsilon >0$. So, we have that if $\lfloor n \alpha/T\rfloor = m$, then $m \alpha < nT < m\alpha + \epsilon \alpha$. Thus, $$n \int_{0}^{T} g(x) \ dx \ge m \alpha \ge nT - \epsilon \alpha \implies \int_{0}^{T} g(x) \ dx \ge T - \epsilon \alpha /n$$ by the same process as before (we just need to add that $f(m \alpha) < f(nT) + \delta $ where $\delta \rightarrow 0$ as $\epsilon \rightarrow 0$) and since $\epsilon$ can be made arbitrarily small, therefore, we're done.
Answer: Well, one should organize his mind I think and proceed by steps. When you deal with a periodic function, the first thing you should keep in mind is that, for any real number $p$, $$\int_0^Tf(x)\mathrm d x=\int_0^Tf(x+p)\mathrm dx;$$ it is not difficult to prove so try do it yourself.
The next step is quite tricky (I admit I've already seen something similar some time ago) and is based on the following observation. Suppose the thesis to be true for $2\alpha\in\mathbb R$ and for any $f$ positive, continuous and periodic of period $T$; then it holds also for $\alpha$ and for any $f$ positive, continuous and periodic of period $T$. The proof of this fact goes as follows: $$T\leq\int_0^T \sqrt{\frac{f(x)}{f(x+2\alpha)}}\mathrm d x=\int_0^T\sqrt{\frac{f(x)}{f(x+\alpha)}\frac{f(x+\alpha)}{f(x+2\alpha)}}\mathrm dx;$$ by Cuachy Schwarz the latter term is lesser than or equal to $$\sqrt{\int_0^T\frac{f(x)}{f(x+\alpha)}\mathrm dx\int_0^T\frac{f(x+\alpha)}{f(x+2\alpha)}\mathrm dx}=\int_0^T \frac{f(x)}{f(x+\alpha)} \mathrm dx.$$ Remark We have use essentially that the functions considered are positive, for otherwise there could be problems with the square roots and with Cauchy Schwarz.
Now we observe that, for any positive, periodic of period $T$ and continuous function the thesis is true for $\alpha=nT$, with $n\in\mathbb Z$. Then an easy induction proves that the result is true for all the reals of the form $$\alpha=T\frac{n}{2^k}, \; n\in\mathbb Z, k\in\mathbb N.$$ Then we are done, since these numbers are dense in $\mathbb R$.
Comment: In your proof, should $T\leq\int_0^T \sqrt{\frac{f(x)}{f(x+2\alpha)}}\mathrm d x$ be $T\leq\int_0^T\frac{f(x)}{f(x+2\alpha)}\mathrm d x$ instead?
Comment: Oh no.. look how the proof goes.. I supposed the base case to hold FOR ANY periodic positive and continuous function..