Cheap acoustic guitars versus more expensive models: Which materials and/or construction elements have the biggest impact on sound quality?

Question: I am referring to guitars of the same body type equipped with identical strings. Do different materials influence sound positively by such an amount that a non-professional  could see the extra value for the extra money spent? I am excluding aesthetic differences.
Answer: The one thing that will make the biggest difference in the way an acoustic guitar sounds, is the material used to make the top which is commonly referred to as the "soundboard".
The body of an acoustic guitar consists of the top (which has a sound hole cut into it), the back and the sides.
Less expensive acoustic guitars will generally use what is known as a laminate "wood" for constructing the the entire body of the guitar, including the top.
A solid top is milled from a solid piece of wood that is large enough to be cross cut into pieces that can be used for the top of the guitar.  Laminate is less expensive because it is made from thinner (less expensive) pieces of wood pressed and glued together, usually with the grain of each layer running opposite one another to provide more strength.
The reason we say the top is the soundboard - is that most of the sound (not quite all) results from the vibration of the top- which creates sound waves much the same way as does a speaker vibrating.  The vibration of the strings (which would make very little noise by themselves) is transferred to the top through the saddle (on which the strings rest) and the bridge (directly under the saddle and glued firmly to the top).
A well made and properly braced solid top will vibrate more freely and resonate more than will a laminate top.  The glue in the laminate top tends to dampen the vibrations, and the layering with opposing grain, while adding structural stiffness to the laminate top, tends to create a sonically stiffer top as well (less vibration = less sound and less sustain).
While it's no guarantee of the overall quality of the workmanship and build of the guitar, in general, you will only find solid tops on the higher end (more expensive) of any guitar manufacturer's line of guitars.
Solid top guitars will cost more, but if there is any one factor that will most predictably result in a better "sounding" guitar, a solid top verses a laminate top creates the most reliable line of demarcation.
Solid back and sides are reserved for even more expensive guitars, but do not make nearly as big an impact on the sound of the guitar as a solid top will.
So a good step up from in terms of sound - from an all laminate body acoustic guitar, would probably be to one with a solid TOP - with laminate back and sides.  Next step up from there, is all solid top, back and sides - but the more solid wood you have in your guitar body, the more susceptible it becomes to the environment (read more maintenance required to protect your guitar from unfavorable conditions).
Be aware that the top material (spruce, cedar, mahogany, maple, sapele, koa, etc.) will affect the tone of the guitar.  If you elect to go with a solid top, if there are different wood types offered within your budget, you may want to listen to the way the top wood colors the tone to see which sounds you prefer.  But that is another discussion altogether.
Answer: "cheap" does not only implicate sound quality.
Really cheap means CNC milling from cheap wood.  Since that means that the wood is not worked with considering its strengths and grain and is not yet stable, the result will not resonate well and/or warp so soon that the instrument becomes unplayable.
Then we have playability: how far do you have to press the strings over higher frets?  For a good instrument, strings will not snare, yet you still only have to press down very little.
A medium instrument requires more work with your fingers and delivers less sound.
A cheap instrument will probably require less work in the first half year (and deliver even less sound), and then you won't even be able to play all frets.
Answer: First of all, you shouldn't compare a guitar as cheap or expensive by looking its price or brand while buying a guitar. But these things makes difference :

The guitar wood : guitar wood material is so important for getting the sound. Good guitars holds resonance and voice of every note, and wood quality is one of them.
Guitar fretboard : Fretboard wood, thickness it an important criteria for a good guitar. In my opinion, too wide fretboards decreases playability, too thin ones brings sustain problems. It's up to you.
Manufacture place : I will generalize this matter. Generally, guitars made in Indonesia and China are being categorized as cheap. Of course there are exceptions.

In final, good guitars can last longer, have good sound quality, and good playability.
Try them, play them, and you'll feel the difference. As like i said, brand or price is not a criterion for quality.


How can I enlarge the Mac's preview window?

Question: Pressing space on a selected file in Finder evokes a preview window. Can I enlarge the size of this window by default to get a larger preview e.g. of images?
Answer: This is answered over here, but basically you'll need to edit the "QLPreviewHeight" and "QLPreviewWidth" values in the Info.plist file inside the QuickLook plugin that handles images (you'll need select the plugin and choose "Show Package Contents" to get at the plist).
You can see your list of plugins with the command: qlmanage -m plugins
If qlmanage shows that "public.images" are handled by the built-in plugin (/System/Library/QuickLook/Image.qlgenerator), you shouldn't need to adjust dimensions since the window opens to the image's size by default. However if you do need to make changes, just copy the plugin into your directory (~/Library/QuickLook) and then edit it with Apple's XCode (downloadable from the App Store).
Answer: You should be able to click/drag the corners of the Quick Look window. I at least know you can in OS X El Capitan.
Comment: This works once but the question is about setting a default.

How can I enlarge the Mac’s preview window?


How to calculate stock move probability based on option implied volatility and time to expiration? (Monte Carlo simulation)

Question: I am looking for one line formula ideally in Excel to calculate stock move probability based on option implied volatility and time to expiration?
I have already found a few complex samples which took a full page of data to calculate.
Is it possible to simplify this calculation in one line formula with the following variables:

Current stock price
Target Target Price
Calendar Days Remaining
Percent Annual Volatility
Dividend=0, Interest Rate=2%
Random value to get something similar to Monte Carlo model?

I need these results:

Probability of stock being above Target Price in %
Probability of stock being below Target Price in %

similar to optionstrategist.com/calculators/probability
Any recommendations?
Answer: If you use a risk-neutral pricing model and consider the probability there, then you get the probability with respect to a risk neutral measure, in addition that probability depends on the chosen numeraire. For example, in Black-Scholes model  taking the risk-neutral measure with respect to the bank account $B$ gives
$$P(S(T)<K) = Q^{B}(S(T)<K) = \Phi(d_{-})$$
and taking the risk-neutral measure with respect to the asset $S$ you get
$$P(S(T)<K) = Q^{S}(S(T)<K) = \Phi(d_{+})$$
If you like to have a real world probability you have to consider the market price of risk and a real estimate for the volatility (not the implied one). Both are not listed in your parameters. If you like to get this probability use the first formula, but replace the interest rate $r$ with the drift of the stock (which contains the market price of risk) and the implied volatility with an appropriate estimate (you might consider historic volatility or assume that implied vol is an appropriate estimate or have a different view).
Since you mentioned Monte-Carlo simulation: I have a spreadsheet implementing a Monte-Carlo simulation of a Black-Scholes model (using multiple time-steps). The calculation of $d_{-}$ can be found in this sheet too. The sheet is here: http://www.christian-fries.de/finmath/spreadsheets/
Answer: If you are happy with the OptionStrategist probability values, why don't just do it exactly how they do it:
<code>function Covered() {

form=document.callreturn;
p=form.price.value;
q=form.strike.value;
t=form.days.value/365;
v=form.volatility.value/100;

vt=v*Math.sqrt(t);
lnpq=Math.log(q/p);
d1=lnpq / vt;

y=Math.floor(1/(1+.2316419*Math.abs(d1))*100000)/100000;
z=Math.floor(.3989423*Math.exp(-((d1*d1)/2))*100000)/100000;
y5=1.330274*Math.pow(y,5);
y4=1.821256*Math.pow(y,4);
y3=1.781478*Math.pow(y,3);
y2=.356538*Math.pow(y,2);
y1=.3193815*y;
x=1-z*(y5-y4+y3-y2+y1);
x=Math.floor(x*100000)/100000;

if (d1<0) {x=1-x};

pabove=Math.floor(x*1000)/10;
pbelow=Math.floor((1-x)*1000)/10;

form.pbelow.value=pbelow;
form.pabove.value=pabove;

}
</code>
This is JavaScript, but it should be rather straightforward to do it in Excel.
Comment: :) Just set the `form.volatility.value` to your IV value. No additional changes required. I mean this code doesn't care if you use IV or historical vol. IV and historical vol are just 2 methods to get estimate true volatility of the stock.
Comment: @Vtech I think you don't need to change anything. You just need to use annualized IV rather then historical volatility. It all depends on your approach: some people prefer use historical volatility, while others believe that implied volatility is more reliable.
Comment: Thanks Aleksey! That's a bit longer then one line. But should work if no simpler solution exist.
Comment: Actually the calculation itself is pretty short. I think you can squeeze it in one excel formula. It's just reading values/writing them back that makes it long.
Comment: The only problem this script uses historical annual stock volatility and i would like to use option implied volatility. Do you know how to change this script to use option implied volatility rather then historical annual volatility?
Comment: Да, Алексей ;) I want to use IV.  Do you know how to change this script to use option implied volatility rather then  historical volatility?
Comment: let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/7351/discussion-between-alexey-kalmykov-and-vtech)
Comment: The Output on the website uses reverse values for pbelow and pabove; kind of strange
Answer: Not sure about all of the complicated math and programming above, but I can tell you that, if you want to calculate for 1 Standard Deviation from the current stock price X days away, the following calculation will give you a +/- value from the current stock price.
1 StdDev Move = (Stock Price X Implied Volatility X the Square Root of 'how many days') all divided by the Square Root of 365.
Add this value to the stock price for the Upper Range and subtract it for the Lower Range.  This will be 68% of the expected range (which is what is considered the normal move for a stock most of the time - 1 Standard Deviation).
Comment: Why negative votes? This is a great shortcut calculation.
Answer: I think that you may be looking for
$$
\mathbb{P}(S_T<K) = \frac{\partial P}{\partial K}(K) = 1 + \frac{\partial C}{\partial K}(K)
$$
where $P(K)$ and $C(K)$ are the european put and call undiscounted price functions for the maturity $T$.
The proof goes (roughly) as this:
$$
\begin{eqnarray}
\frac{\partial P}{\partial K} &=& \frac{\partial}{\partial K}\int_{0}^{\infty} (K-S_T)^+p(S_T,T,S_0,t_0) \\
&=& \int_{0}^{\infty} \frac{\partial}{\partial K}(K-S_T)^+p(S_T,T,S_0,t_0) \\
&=& \int_{0}^{\infty} \textbf{1}_{\{S_T<K\}}p(S_T,T,S_0,t_0) \\
&=& \mathbb{P}(S_T<K) .
\end{eqnarray}
$$
The one-line formula goes as
$$
\begin{eqnarray}
\frac{\partial P(K,\sigma(K))}{\partial K} &=& \frac{\partial P}{\partial K} + \frac{\partial P}{\partial \sigma}\times\frac{\partial \sigma}{\partial K} \\
&=& \Phi(d_-) + K\phi(d_-)\sqrt{T}\times\frac{\partial \sigma}{\partial K} .
\end{eqnarray}
$$
Where
$$
d_- = \frac{\log(F_T/K) - \frac{1}{2}\sigma(K)^2T}{\sigma(K)\sqrt{T}} ,
$$
being $F_T$ the forward price of the stock at time $T$.
Note that if you have a flat volatility (Black-Scholes model), then the probability is simply
$$
\mathbb{P}(S_T<K) = \Phi(d_-) .
$$
For a market with non flat implied volatilities you still have to find the term $\frac{\partial \sigma}{\partial K}(K)$ doing some sort of interpolation/extrapolation of the volatility surface. Also, you should have to make sure that when interpolating or extrapolating you get admissible cdf's, otherwise a static arbitrage is guaranteed.
Answer: You can certainly calculate the probability of changes in variation but I have not come across a model that only looks at an isolated iVol and its associated term and then deriving a directional probability.
However, what you can do, and what options traders do all the time is to look at changes in skew which involves a range of implied data points. In Fx traders look at risk reversals. Also, in the short term, where trades in the option relative to the book take place has a bearing on directional probabilities. I am not gonna provide a formula, because I use some of that as part of my own business, just trying to push you into the right direction.
Answer: Isn't the option's delta a close approximation for the probability the option will be in the money?


TeamCity - Git push from agent

Question: I've got a TeamCity server set up to checkout src from GitHub on the agents using "Default Private Key" and a config file in .ssh that looks like this:
Host email@example.com
    IdentityFile ~/.ssh/id_rsa.shop
    StrictHostKeyChecking no

Host github.com
    IdentityFile ~/.ssh/id_rsa.shop
    StrictHostKeyChecking no

and this works fine.
Now i want to push from the agents.
However when i do this the push command hangs due to user input:
The authenticity of host 'github.com (188.8.131.52' can't be established.
RSA key fingerprints is 'xxx....xxx'
Are you sure you want to continue (yes/no)
Warning: Permently added '' to known hosts.
Connection closed by 188.8.131.52
Fatal: The remote end hung up unexpectedly.

If i do this manually it still fails with permission denied no matter wether i type yes/no.
The "Default Private Key" has read/write permissions accoring to github, so im a bit lost.
Only thing i have observed is that the github ip looks very local, but how can that be when the agent has just done a agent side checkout? Could this be a firewall?
Can anyone explain to me what im missing?
Answer: Turns out there was a rather big catch with the setup.
Apperently for reason i do not quite understand the user context/profile changed once i called git.
This would change the homedir.
This can be verified by looking at the Git etc file which does the profile change called: profile:
# Set up USER's home directory
if [ -z "$HOME" -o ! -d "$HOME" ]; then
  HOME="$HOMEDRIVE$HOMEPATH"
  if [ -z "$HOME" -o ! -d "$HOME" ]; then
    HOME="$USERPROFILE"
  fi
fi

if [ ! -d "$HOME" ]; then
    printf "\n\033[31mERROR: HOME directory '$HOME' doesn't exist!\033[m\n\n"
    echo "This is an error which might be related to msysGit issue 108."
    echo "You might want to set the environment variable HOME explicitly."
    printf "\nFalling back to \033[31m/ ($(cd / && pwd -W))\033[m.\n\n"
    HOME=/
fi

# normalize HOME to unix path
HOME="$(cd "$HOME" ; pwd)"

I fixed this issue by forcing the home dir to current user as so:
set HOME=%env.USERPROFILE%

The problem was in an init script of git.
Moreover I had to modifiy the config to:
Host webshop_github
HostName github.com
User git
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa.shop

Comment: That's really weird. I've stuck with the same problem on Windows agent. And I've solved it using your solution. Many thanks!
Answer: Actually I've dipped a bit further and found another solution thanks to @Christian Mikkelsen and answers in this thread: git.cmd vs git.exe - what is the difference and which one should be used?.
You just should not use the original git.exe when manually working with git, but the wrappers - gitk.cmd or cmd\git.exe. Please note that cmd\git.exe isn't the same as bin\git.exe. Teamcity itself uses bin\git.exe as it knows how to work with it. But if you work with git manually you should use cmd\git.exe.
The problem you have to solve is how to pass the path to cmd\git.exe into your script. I support it can be done using custom parameters or perhaps overriding the env.TEAMCITY_GIT_PATH before executing your script.

TeamCity - Git push from agent


How did Kepler formulate his second law from data?

Question: It's amazing that Kepler derived his three laws emperically and then Newton rederived them from his own laws of motion. Its conceivable how Kepler derived the first and third laws, but the second law? How would Kepler have measured the area of the arcs swept out in equal time intervals just by looking at the data and why would he have the motivation to do this in the first place?
Answer: Kepler analyzed an enormous amount of data provided by Tycho Brahe. The data provided by Tycho Brahe must have represented a monumental effort.
In my opinion, it must have been more grueling for Brahe to collect all the raw data than it was for Kepler to analyze the data. The amount of number crunching Brahe did was staggering.
If you could plot all the data to scale on a sheet of paper and actually see the ellipses and the time lapses between locations, I don't think it was all that much of a leap to see that the longer, narrower slices of pie could possibly equal the areas of the shorter, fatter slices of pie. To me, that's pretty intuitive.
Motivations for finding answers to huge questions of the day? There are at least several: Fame, glory, wealth, prestige, the thrill of being the only person on Earth to know a truth for a short period of time before you publish your results, etc.
Comment: No I don't mean motivation like that. I mean motivation for thiking about areas. Because its not so easy to draw an ellipse which evolves over time: you can graph a few points and write the point in time at each point, and the best thing you could do today is make an animation which traces the ellipse over time. Even using an animation, the areas relationship is not obvious. I would like some more detail please.
Comment: Its not easy to notice that from data though, because you would need to draw the ellipse, and at each point on the ellipse, know the corresponding point in time. Just looking at time coordinates like that does not make the area thing obvious at all.
Comment: @Joshua Benabou - I would say that the amount of data Tycho Brahe provided was so voluminous, that precise ellipses could have drawn by Kepler. After that, I think Kepler's intuition would have revealed the equal area possibility and he would have begun measuring. The "equal area in equal time" concept seems very intuitive to me.
Comment: Take this with grain of salt, but here is what I think probably happened. The orbits are almost circles, so the constant rate of area sweeping was most probably quite  obvious and uninteresting first. The really difficult part was to realize that the discrepancies between description based on circular or else shaped models (ovals) of the orbit of Mars and the actual motion of the planet could be resolved by assuming the orbits are ellipses.
Comment: I heard in some document this took Kepler some time to realize. He didn't think of ellipses as probable for quite some time. After he realized them, it was probably quite easy to check that if the radius is drawn from focus instead of the center, the rate of area sweeping was still constant.
Comment: Ok thats a much better explanation. For circles its quite obvious just by dividing the circle into equal-arcs and looking at the corresponding time intervals for each arc.
Comment: "provided by"… or "stolen from" Tycho…


Positive integer solutions of $a^3 + b^3 = c$

Question: Is there any fast way to solve for positive integer solutions of $$a^3 + b^3 = c$$ knowing $c$?
My current method is checking if $c - a^3$ is a perfect cube for a range of numbers for $a$, but this takes a lot of time for larger numbers. I know $c = (a+b)(a^2-ab+b^2)$, but I can't think of a way this would speed up the process. Factoring numbers can be done fairly quickly but then the values of $a$ and $b$ have to be chosen. This is for a previous question I had about Fibonacci numbers. Any relevant literature is appreciated.
Comment: another way to express $a^3+b^3$ might be $(a+b)[(a+b)^2-3ab]$.
Answer: A very fast way to see that a positive integer $c$ is not the sum of two cubes are modular constraints. The equation $a^3+b^3=c$ has no integer solutions if $c$ satisfies one of the following congruences:
$$
(1) \quad c\equiv 3,4 \mod 7
$$
$$
(2) \quad c\equiv 3,4,5,6 \mod 9
$$
$$
(3) \quad c\equiv 3,4,5,6,10,11,12,13,14,15,17,18,21, 22, 23, 24, 25, 30, 31, 32, 33, 38, 39, 40,
41, 42, 45, 46, 48, 49, 50, 51, 52, 53, 57,
58, 59, 60 \mod 63
$$
On the other hand, there are intrinsic properties of $c$ known, such that $c$ is the sum of two squares:
Theorem (Broughan 2003): Let $c$ be a positive integer. Then the equation $c=a^3+b^3$ has solutions in positive integers if and only if the following conditions are satisfied:
1.) There exists a divisor $d\mid c$ with $c^{1/3}\le d\le 2^{2/3}c^{1/3}$ such that
2.) for some positive integer $l$ we have $d^2-c/d=3l$ such that
3.) the integer $d^2-4l$ is a perfect square.
Comment: Here is a link: http://researchcommons.waikato.ac.nz/handle/10289/2026.
Comment: There are also modular constraints which don't exclude values of $c$ but lead to modular conditions on any associated $a^3$ and $b^3$.  For example, if $c \equiv 2\mod 7$ then $a^3,b^3 \equiv 1\mod 7$.
Comment: I'm curious: is there a set of modular constraints that only test for sums of _positive_ cubes? Because as the test stands, it's flagging perfect cubes and differences of cubes a well. I believe the OP clearly stated that he wanted _positive_ integer solutions.
Comment: @BrianJ.Fink  The modular constraints are best thought of not as flagging possible solutions but as excluding impossible values, either impossible values of $c$ or, for given $c$, impossible values of $a^3,b^3$. The exclusion of values which are impossible for modular reasons from the set of all positive values of $c,a^3,b^3$ can help to find positive solutions faster.  It doesn't matter if, as is the case, the modular constraints also apply to $a^3+(-b)^3=c$.
Comment: @AdamBailey it remains that the modular constraints do not exclude nonpositive values of a,b and since the OP requested _positive solutions,_ it would be far better to come up with constraints that show when $c=a^3+b^3$ has no solutions in $\mathbb{N}$, not just $\mathbb{Z}$.
Comment: @AdamBailey after further experimentation I have discovered that the modular constraints are the same no matter what part of the number line they're applied to! I guess I'll have to look elsewhere.
Answer: You might as well concentrate on the case that $a$ and $b$ are relatively prime. This means that $a^{2}+b^{2}-ab$ must either be a product of primes all congruent to $1$ (mod $3$), or else $3$ times such a product. Hence if you write $c = 3^{m-1}d\cdot3f$, where $3^{m}$ is the exact power of $3$ dividing $c$ and $d$ is the product of all prime divisors of $c$ which are congruent to $2$ (mod $3$) (including multiplicities), then if $m=0$, we need to express $f$ in the form $x^{2}+y^{2}-xy$ for integers $x$ and $y$ (and this can be done). If $m >0$, we need to express $3f$ in the form $x^{2}+y^{2}-xy$ for integers $x$ and $y$ (and this can be done). For every such expression (and the number of such expressions can be calculated precisely from the rational prime factorization of $f$), we need to check whether or not $d = x+y$ when $m = 0$, or $3^{m-1}d = x+y$ when $m >0$.
While this is theoretically correct, I can't claim that it is fast or efficient (it depends on factorization properties of the Eisenstein integers $\mathbb{Z}[\omega]$, where $\omega = e^{\frac{2 \pi i}{3}}\!\!$). However, let's analyse $c = 468 = 9 \times 52$. According to the above method, we have to express $39$ in the form $x^{2}+y^{2}-xy$ for integers $x$ and $y$ and we should have $x+y = 12$ if we are to obtain $x^{3}+y^{3} = 468$. At this stage there are few possibilities to check and up to symmetry, the solution is $x = 5,y = 7$.  It might be helpful to note that in general, we need $(3^{m-1}d)^{2} > 3f$ when $3$ divides $c$ and $d^{2} > f$ when $3$ does not divide $c$, if there is to be any chance of having  solution to $c = a^{3}+b^{3}$, with $a$ and $b$ both positive.
Answer: $c=(a+b)(a^2−ab+b^2)$ should actually be quite helpful. After factoring $c$, you find all possibly ways of writing $c = xy$. Let $x = a + b$ or $b = x - a$, so
$$
a^2-ab+b^2 = a^2 - a(x-a) + (x-a)^2 = 3a^2 - 3ax + x^2 = y
$$
Solve this quadratic equation for a and check that a is an integer.
Obviously many factors need not be examined: If we keep the sum $x = a+b$ fixed, then $a^3 + b^3$ is between $x^3/4$ and $x^3$, so $x$ must be between $c^{1/3}$ and $(4c)^{1/3}$.
After reading previous posts, this seems to be a published result, cited as (Broughan, 2003). Had a look at the paper. Oh well, you can sure make this complicated.
For not very large c, say $c < 10^9$, brute force may be quicker: Let a = 0, b = $c^{1/3}$, rounded down. As long as $a^3 + b^3 < c$ increase a by 1. If $a^3 + b^3 = c$ note that you found a solution. Then decrease b by 1, repeat until $a > b$.
Comment: You solve one quadratic equation for every factor x of c, instead of checking x different values.
Comment: How is this f aster than checking every value of $a$?


How can I view the active threads of a running program?

Question: I know I can see all running processes in Task Manager. But how can I see the single threads that run inside these processes?
Answer:
Get Process Explorer.
Enable Show Details for All Processes from the File menu:

In the main pane, select the process you're interested in:

Open the context menu (right-click) for the selected process and click Properties:

On the Threads tab, you'll be able to see a list of the running threads inside that process:

Symbols
If your troubleshooting requires you to get more detail, it is often very helpful to load debugging symbols into Process Explorer. This is how:

If you don't already have a Windows debugger installed, you're going to have to install the Debugging Tools for Windows first.
In Process Explorer, open Configure Symbols... from the Options menu:

If you have the Debugging Tools (or another Windows debugger) installed, Process Explorer will automatically find the dbghelp.dll file. Otherwise, set the correct path here.

The Symbols path should look something like:
SRV*C:\Symbols*http://msdl.microsoft.com/download/symbols

The only part you'll want to adjust is C:\Symbols. That's the location where the debugging symbols will be cached.
Comment: Omg, why didn't they built it in task manager, it is an obvious feature…
Comment: ...obvious feature for devs: Windows is for grandma-level users so it is better kept hidden.


Pattern tile shape. Artboard size

Question: I am a starter in illustrator. I make pattern and put it in swatches panel. When I open it from swatches panel, the pattern tile has a rectangle shape even if I have given the size of a square at first (before drawing and making pattern). 1) How can I have a square pattern tile not rectangle? after that, 2) How can I make a new  artboard of my pattern tile?(When I open my rectangle(!!!) pattern tile from swatches panel, and draw a new square by ellipse tool to drag the tile to it,suddenly all the screen is my pattern tile!)(There is no new white square to see and drag to it)
Can anybody help me solve the problemsa? Many thanks.
Answer: A patter tile, in almost all instances, has no correlation to artboard size.
You can change the "tile" aspect of a patter in Pattern Editing Mode by clicking the Tile edit button on the Pattern Editor Panel. This allows you t alter the aspect of the tile shape.

If you want a square tile, then you need to ensure the Tile Type is set to Grid. Any other setting will result in a non-square shape. i.e. "Brick" results in rectangles, "Hex" in hexagons.

Panel may look different in CC 2020, but it should still be relatively the same in function.

To fill an artboard with a pattern, draw a rectangle on the artboard and then click the pattern swatch in the Swatches Panel to apply the pattern fill. It's the same procedure you'd use to fill a rectangle with color. The only difference is the swatch you click. You do not want to be in Pattern Editing Mode when filling the rectangle.
Comment: Thanks. I chose Grid and I had a square. But I still have problem with my pattern tile coloring. I go Window > Pattern Options > Make Pattern. Then I click on Fill swatch, I draw a rectangle by the Elipse Tool (on selecting square or rectangle which is around my first drawing, in the middle of the pattern) as my background. 1) This background is like a gride. There is a square or rectangle around the basic drawing which I made pattern tile with. Even if I send it to back.
Comment: Sorry, even for dotted pattern, suppose green circles are in the middle of yellow squares and there is a white stroke around each yellow square!!! But I need just a yellow background without any grid. What is my mistake? Thanks.

Pattern tile shape. Artboard size


What is the explanation of weight in terms of general relativity?

Question: In GR a massive particle falls along geodesics of curved spacetime because there is no "force" on it and it has to follow straight lines. But how can the weight felt by an object on the surface of earth be explained by this concept?
Comment: Weight is the normal force, between the ground and your feet that occurs when the ground gets in your way and stops you from following a geodesic.
Answer: Whwn you stand on the ground on Earth, you are basically in a freefall on a geodesic, but the ground is in your way. What you feel is the ground keeping you from freefalling.
It is a misconception that the effects of gravity are caused by mass. This is due to stress-energy. Even a photon, that has no rest mass, does have stress-energy and has effects of gravity.
It is a misconception too that only massive objects will follow the geodesic. GR specifically explains this effect of gravity with the phrase "gravity bends the fabric of spacetime" because all known particles in the SM will have a altered trajectory when they interact with the gravitational field. Yes, even a photon's trajectory will be altered by the gravitational field of the Earth, and the photon will try to follow the geodesic. The reason you do not only see photons fall towards the center of Earth, exactly on the geodesic, is that the Earth has relatively low stress-energy, and it can only alter the photons trajectory a little bit.
Although you would think that as you stand on the ground, you are in standstill relative to Earth, you are still moving in spacetime, in the time dimension. The universe is set up so and the four vector is set up so that its magnitude needs to be c always. If you are in the gravitational field of the Earth, time dilation will cause you to slow down in the time dimension (time will pass slower for you relatively), but because the four vector's magnitude needs to be c, the spatial dimensions will need to compensate. You will accelerate in the spatial dimensions. You will accelerate towards the center along a geodesic. But the ground is in your way, so you feel the ground pushing up(or you feel yourself pushing down).
Answer:
But how can the weight felt by an object on the surface of earth be
  explained by this concept?

I like to say that the reason you are stuck on the surface of the Earth is because the shortest distance between today and tomorrow is through the center of the Earth.
"Weight" is the sensation of that natural motion being constantly interrupted by the Earth, which is moving in a different direction between today and tomorrow.
As Feynman put it, all the interesting physics is where your feet hit the floor.
Answer: Classical physics says weight is a type of force you experience. But it technically is not a force by definition under relativity, since gravity from first principles is a pseudo force by definition, and it is not usually custom, to quantize these fields. (Yet this hasn't stopped gravitons being speculated).


Using Terminal to open a file within a jar file?

Question: How can I open and see within a file within a jar file from within Terminal?
I can use less to print out all the files within the jar file, but how can I open these files?
Comment: Mount the zip file (there are various tools), then open it using `xdg-open`. Remember to unmount afterwards.
Answer: Personally I use jar because it feels more natural, and allows for other operations such as updating contents too. Here are the read commands:
List contents
jar tf myjar.jar
Extract contents to pwd
jar xf myjar.jar
Extract specific file, creating dirs as required
jar xf myjar.jar /foo/bar.class
Extracting the bytecode itself isn't usually terribly useful though. To make sense of it, you need to decompile it into something readable.
There aren't many good java decompilers to choose from. I tend to use JD-GUI, because it's quick and does what I need it to. Frustratingly, its multi-file search functionality never works for me (note that Ctrl+F search-on-the-page is fine). This is no great loss though; you can get it to dump all the sources to disk with Ctrl+Alt+S for perusal with grep/vim/Eclipse etc.
I install it like this:
wget http://jd.benow.ca/jd-gui/downloads/jd-gui-0.3.5.linux.i686.tar.gz
tar xzf jd-gui-0.3.5.linux.i686.tar.gz
sudo mv jd-gui /usr/local/bin/
sudo chown root:root /usr/local/bin/jd-gui
sudo chmod 755 /usr/local/bin/jd-gui

Using it goes something like this:
jd-gui myjar.jar
Ctrl+Alt+S; pick your path & save
Alt+F4
jar xf <path>/myjar.src.zip

Note however that JD-GUI has no CLI interface. If you know of a good CLI decompiler, I'd be very interested to hear of it (there is JAD, but AFAIK that only supports Java < 1.5).
Answer: Using unzip you can pipe a file from the archive to stdout and then into something else to read it, like:
unzip -p /path/to/some.jar path/to/file/inside/jar | less

From memory unzip is not installed by default so you might need to:
sudo apt-get install unzip

Jeff
Comment: Isn't there a way of opening the file without unzipping it?
Answer: jar files are really only zip files you can test this by doing.
file foo.jar

so to list the files you can simple do.
unzip -l foo.jar

To access the files just unzip the file with
unzip foo.jar

If you want to extract only one file then append the files after
unzip foo.jar some/path/in/jar/bar.class

Make sure to use the full path from -l. And keep in mind it will create the same path locally.
Comment: Isn't there a way of opening the file without unzipping it?
Comment: I'll update the answer for that.
Answer: (No rep points, so have to answer to respond to comments by @Kurro)
unzip (-p | -c) <jar-file> <file-in-jar>

The -p and -c options extract the file to standard output; -c gives an extra 2 lines of data at the beginning (which JAR file and which file within the archive).
I found this extremely convenient for reading the Manifest file or the .xml files.  For the compiled .class files, this is useless, but your friend here is javap:
javap -classpath <jar-file> <fully.qualified.class.name>    # without the .class suffix

Some useful options are: -c (decompile to Java Assembly), -private to also show private fields, and -verbose for lots of extra information.  If it's a big file, you may want to pipe the output through less.
Answer: I've always just defined a function to do this:
vijar ()
{
    unzip -p $1 $2 | vi -
}

To use:
vijar jarfilename.jar path/file_to_view


Can any function be used as a hook?

Question: I'm looking to override format_size(), but I'm not sure if this is possible in a module.
If I implement myModule_format_size() or in a theme myTheme_format_size() will the hook be called?
Answer: No.
Not all functions invokes a hook in other modules. As we can see in http://api.drupal.org/api/drupal/includes%21common.inc/function/format_size/7 there is no module_invoke_all is called.
Here is how we define module_invoke_all

Invokes a hook in all enabled modules that implement it.

function module_invoke_all($hook) {
  $args = func_get_args();
  // Remove $hook from the arguments.
  unset($args[0]);
  $return = array();
  foreach (module_implements($hook) as $module) {
    $function = $module . '_' . $hook;
    if (function_exists($function)) {
      $result = call_user_func_array($function, $args);
      if (isset($result) && is_array($result)) {
        $return = array_merge_recursive($return, $result);
      }
      elseif (isset($result)) {
        $return[] = $result;
      }
    }
  }

  return $return;
}

Comment: Thank you. So in theory, there is no way to edit the function above without "hacking core"??
Comment: Yes right now there is no way to extend that function. http://drupal.org/best-practices/do-not-hack-core
Answer: In Drupal, a hook is not a function that is called instead of a function defined from Drupal; it is a function that Drupal, or any third-party module, calls through module_invoke_all(), or module_invoke().
In your case, mymodule_format_size() will never called instead of format_size(), but it will be eventually called as hook_format_size() implementation (whatever purpose it has), if a module invokes that hook.
Since it is not possible to expand format_size(), which doesn't invoke any hook, contrary to format_username(), the only way to change the code executed from format_size() is to act on the functions calling it. In other words:

If format_size() is used in a form submission handler, then you could alter that form to remove that form submission handler, and replace it with your own handler, which doesn't call format_size()
If format_size() is used from a template file that is used from a theme function implemented in a module, you could override the template file in a theme
If format_size() is used from a theme function, you could override the theme function (in a module or in a theme) with a version of the theme function that doesn't call format_size()

Can any function be used as a hook?


Why do we differentiate displacement to get velocity if displacement is given as a function of time

Question: Like if the displacement is given as S=(2t³)and if we are asked to find the velocity in 2 seconds then if we put t=2 in the expression we get 16 which isn't correct. The correct must be dS/dt=6t² and then if we plug 2 in t we get the velocity as 24. Someone plz explain. Why don't we get the correct answer if we don't differentiate and directly plug the value in the expression which was given?
Comment: If you wanted to know the object's weight (or price) at time 2, would you still "plug into" $2t^3$ ?
Comment: what are dimensions of number `2` - is it $[m/s^3]$ or is it just a dimensionless number ?
Answer: It's because  setting t=2 in the first equation tells you the distance the object goes in 2 seconds, not its velocity after 2 seconds.
I would add, per @Agnius Vasiliauskas, that there should be a statement given with the equation that says the coefficient 2 has units of m/s$^3$ in order to make sense.
Hope this helps
Answer: Your displacement equation is faulty, because left side has dimensions of $[m]$ and right side has dimensions of $[s^3]$ (dimensions of left and right side of equation must be the same). Thus it should be $$s = 2At^3$$
where constant $A$ has dimensions of $[m/s^3]$.
In this case speed :
$$ v= \frac{ds}{dt} = 6 A t^2 $$
or variable A is function of time $A=A(t)$ also, then speed is :
$$ v=\frac{ds}{dt} = 2 t^3 \frac{dA(t)}{dt}  + 6 t^2 A(t) $$
In this last case calculus trick is used :
$$ \frac{d}{dk}\big(x(k) \cdot y(k)\big) = y(k) \frac{dx(k)}{dk} + x(k) \frac{dy(k)}{dk} $$
And in general calculus is used in Physics from a long time ago- the point Newton and Leibniz invented it. It's still a main tool in Physics nowadays, so you need to get used to it. Maybe grab some calculus book before jumping to Physical concepts ? Without this knowledge you will loose a lot in Physics. My gut feeling is that you strugle to understand speed and other concepts, because of this exact problem. Newton needed it, so you too
Comment: Any reason of downvote ? Because I have explained main physics rule about checking any physics equation correctness ?
Comment: I didn't down vote, but The equation can be used if you assume (as I did) that the coefficient 2 has units of m/s$^3$. Admittedly it should be stated so.
Comment: Yes, it should be stated as so, because it looks like just dimensionless number.
Comment: Yes I agree with you. But it seemed to me the OP's confusion was with concepts not units
Comment: Now it looks like someone down voted me. Oh well c'est la vie
Comment: Not me, really :-) As for me, I think that explaining speed concept without explaining first dimensional analysis - will do more harm than benefit. I think OP should concentrate on unit dimensions at first. Then understanding physical derivatives will be one step easier to do


Does the "exclude files based on mask" option in Fling ftp actually work?

Question: I'm trying to exclude a directory and some files from being copied to an ftp server but the exclude files mask is ignored.
Has anyone had any success in using it?
Answer: Had a similair problem, then took another look at Filezilla, they've added some nice filtering functionality to prevent certain folders appearing in the transfer list.
Answer: The exclude files mask prevents upload, but the exclude folders mask does not seem to prevent the scan process. So if for instance you have 1000 subfolders and need to selectively exclude some to speed up the process, no can do as far as I can see. Great program, otherwise.
Filezilla seems to have no ability for automated file transfer and the sole programmer indicates that it's not going to happen.


Expression "making a bid/break for freedom"?

Question: What is the difference between "making a bid for freedom" and "making a break for freedom"? In which situations would one use one and not the other?
Answer: In the context you're referencing, a bid is

an attempt or effort to achieve something

whereas a break is

• a rush or dash in a particular direction, esp. by an attacking player or team : he made a bounce pass for a basket on the break in the second quarter.
  • a breakout, esp. from prison.

The distinction is that a bid may or may not risk anything, whereas a break often risks much or all.
[References from NOAD]
Comment: Hmm - it's worth noting that a bid is very literally when you propose a price to be paid for something, whether a bet like stock options, or for purchase at an auction. (I think any attempt at freedom carries a price, a risk, you're putting something on the line - psychologically or otherwise!)  A "break for..." is indeed when you break out of some situation, physical or metaphorical. I had to break for freedom from my aged mother; on the other metaphor anytime you take a business risk to achieve more independence, that's a bid for freedom (it's pricey, and risky too).
Comment: In a bid for freedom, you are putting up some of your own wealth/time/etc in a bid for freedom. The "bid" is how much you're putting on the line.  (Eg: **"Well I've quit my job, and put $50,000 on the line in my bid for freedom in a new life running a coffee shop."**) Whereas in a break for freedom, you're about to destroy a prison, marriage, or other physical or social institution so that you can be free.  (Indeed you may be eg. shot attempting to escape in the process.)


Syntastic and Python-mode together?

Question: I have installed python-mode in VIM. But I also have Syntastic installed. Since both do syntax checking, is there going to be a conflict? How can I turn off Syntastic for Python files?
Thanks for any help
Answer: To expand on @abjuk's answer, you can disable based on file extension with:
let g:syntastic_ignore_files = ['\.py$']

This will only work for files that end in .py, though. It won't work for other files in where Vim thinks that filetype=python. For example, a file that starts with a shebang like #!/usr/bin/env python will still put Vim into python mode.
Syntastic also supports syntastic_mode_map (see :h syntastic_mode_map), which the docs seem to indicate should allow disabling based on the filetype, but I can't get it to work.
Another option is to leave Syntastic enabled, and disable python-mode's syntax checking:
let g:pymode_lint = 0

This is what I use, because I prefer Syntastic. It resolves the conflict, although it isn't exactly what you asked.
Answer: This is answered in the manual (see :help syntastic-pymode):

Syntastic can be used along with the 'python-mode' Vim plugin (see https://github.com/klen/python-mode). However, they both run syntax checks by default when you save buffers to disk, and this is probably not what you want. To avoid both plugins opening error windows, you can either set passive mode for python in syntastic (see syntastic_mode_map), or disable lint checks in 'python-mode', by setting pymode_lint_on_write to 0. E.g.:

let g:pymode_lint_on_write = 0

Answer: I don't work in python, so I can't tell you if there will be a conflict, but you can turn off Syntastic for python files - see :h syntastic_ignore_files.
Comment: Okay that sounds like a good idea. It's safer to do that as Python Mode is supposed to do syntax checking anyway.

Another issue is that Syntastic does not detect any errors in my java or C code - or when it does, it's all nonsense. It marks correct code that compiles as invalid and doesn't detect syntactically invalid code. Any ideas?
Answer: I use the following to disable syntastic (not let syntastic trigger on file write) for Vim buffers which have the filetype python:
autocmd FileType python let g:syntastic_check_on_wq = 0

See my .vimrc.

Syntastic and Python-mode together?


Maximising VirtualBox guest machine window size

Question: I am running Ubuntu 16.04 LTS inside VirtualBox on a MacBook Air 7,2, but the guest screen window size is less than the host display size. I have seen a suggestion that this is possible by installing something called a Guest Additions inside the VB instance from the Devices menu - I tried to this but I get the following error.
Answer: Open Terminal and run the following to install VirtualBox Guest Additions:
<code>sudo apt-get install virtualbox-guest-utils
</code>
Comment: Thanks, it works.  Additionally, how I increase the maximum size of the guest machine video memory? The maximum is set to 128 MB (in Machine -> Settings -> Display -> Screen), which is way below the 4 GB base memory I specified before created the guest (this is displayed in Machine -> Settings -> System -> Motherboard) - the host machine memory is 8 GB, so that's why I set the guest machine memory to 4 GB.
Comment: Also, I've enabled bidirectionality for the Shared clipboard and drag'n'drop settings (Machine -> Settings -> General -> Advanced), but it doesn't seem to have any effect. My understanding is that this allows selected text in either the guest machine or host machine to be copied between each other seamlessly.  This does not happen at all.
Comment: @ramius You have 8 GB of video memory?! What graphics card do you have? To use the maximum 256 MB video memory, you need to modify the .vbox file with a text editor and change the VRAMSize. If Guest Additions features don't appear to work, make sure you've restarted the instance (preferably using the normal reboot feature).
Comment: Lol, no, not video RAM, I mean just standard RAM.  I think I was confusing the video memory with that - it can't exceed the host graphics card capacity obviously.  Mine is an Intel HD Graphics 6000 card with 1536 MB.


Ip6tables script for a ipv6 router

Question: I am using gogoc tunnel broker on my ubuntu pc for enabling ipv6. I want to use my Ubuntu pc as ipv6 router. I have enabled router mode in the gogoc client. I am using radvd for advertizing the router on the local LAN. tun is the tunnel (WAN) interface. br0 is the LAN interface (wan0 and eth0 have been bridged to make the laptop a wireless accesspoint). What firewall rules can I use to enable packet forwarding and to have a fairly good security for the router and the LAN devises.
Answer: For Linux-based routers, I find that shorewall6---a firewall tool based on ip6tables---works quite well. By using a front end tool like shorewall6 instead of raw ip6tables, you can dispense with certain important but fiddly details, like wondering about the vaguaries of ICMPv6 (which types do I need to accept? which to drop/reject?), as they've already been competently dealt with.
To configure shorewall6, you edit a small number of well-documented config files in /etc/shorewall6. At the very least, you would modify these files:

zones, where you give names to your networks;
interfaces, where you list your network interfaces and the zones they are attached to;
policy, where you define your default policies for forwarding between zones (ACCEPT, DROP, etc);
and rules, where you can create specific exceptions to your policies.

(There are a few other files as well, but for most situations, the defaults are fine.)
In your case, you could define two zones, say lan and wan. Your default wan-to-lan policy would be DROP, while your default lan-to-wan policy would be ACCEPT. Then, if, for example, you wanted to allow ssh connections to particular hosts in your lan zone from the wan zone, you would add those exceptions to the rules file.
In summary, using a front end tool like shorewall6 makes it very easy to create a robust and secure router/firewall---certainly easier than using raw ip6tables---because it creates some easily understandable abstractions for you to configure (zones, policies, rules), and then it takes care of the underlying details.
Answer: I can't say that I'm familiar with that specific tunnel broker, I'm assuming that you received a /64 for your hosts. There are some tunnel brokers which provide a /48 in which case you'll need to adjust the rules a bit. These are in iptables-save format:
*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]

# Allow established connections
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT

# Allow ICMPv6 traffic (required for IPv6) This could be tightened up but it must
# be done very carefully unless you know what you're doing. It could block all
# routing
-A INPUT -p ipv6-icmp -j ACCEPT
-A FORWARD -p ipv6-icmp -j ACCEPT

# Allow traffic from your internal hosts to the outside world
-A FORWARD -s <your address block>::/64 -j ACCEPT

COMMIT

You'll need to replace "<your address block>::/64" with whatever address range you're assigned.
This firewall will prevent all outside connections to your local IPv6 addresses while allowing them access to everything. If you need to provide services on your internal IPv6 hosts you'll need to add allow rules in the FORWARD chain at the end (but before the COMMIT).
Comment: I was not able to find out the address block assigned to me. The ip that I recieved ends with `/128`. Something like this: `2001:5c0:1400:b::9e55/128`. I got that address from here: http://linuxgazette.net/184/silva2.html

Ip6tables script for a ipv6 router


Is it "a tough row to hoe?", or "a tough road to hold?"

Question: Is it an old farming metaphor, or a military saying? Where did this(these) saying(s) originate?
Comment: Is this a possible candidate for the eggcorn tag?
Comment: This is in [the eggcorn database](http://eggcorns.lascribe.net/english/73/road/), unfortunately no genealogy is given.
Answer: The original form of the phrase appears to be "a hard row to hoe". Now, "tough row to hoe" is found at least as far back as 1890:

She's got a tough row to hoe, Dilly Gage has. She used to try to keep
  folks from knowin' how cantankerous he was, but she couldn't.

while 1963 seems to be the earliest occurrence of "tough road to hold", and it is noted as an error:

Certain little errors may be the result of spelling, hearing, or
  carelessness - "a tough road to hold"

But we find "hard row to hoe" even earlier. It's found in Dickens' All the Year Round magazine in 1890, but the earliest use is no later than 1818:

He loves to contend with difficulties; and if he had not a hard row to
  hoe, would place himself in some sphere demanding effort, in order to
  extricate himself.

Since it's used without explanation in the 1818 book, it must have been regarded as a well-known expression even by then. So the origin is as a farming metaphor, and seems to be chiefly American in usage.
Comment: haha - I saw your comment as soon as I hit *Post your answer*. You're quite right, of course. So I just went back and changed mine to the next oldest citation, in 1818. I doubt the road/hold variants would have turned up until much later, but to be honest I can't be bothered to check that myself just now.
Comment: The 1818 date is actually 1848. An engraving on the previous page is dated 1848, and the date on the title page is smudged and looks like 1818, but seems to be a smudged 1848.  And Charles Dickens, whose magazine it appears in, was was only six in 1818.
Comment: There is a supposed 1800 reference in that Google search, but it is wrong. Google indexed the year that work incorrectly. It is not from 1800, but from 1899, as you can see in the title page and headers of the work itself.
Answer: The road and hold variants are eggcorns deriving from the orginal "Tough/hard row to hoe", an agricultural expression relating to hoeing one's row (with an actual tool) while working in the field, that goes back to at least 1818.
Answer: I live in the South where much cotton is raised.  Cotton was "hoed" to get rid of the weeds growing in the rows with the cotton.  Believe me, "hard row to hoe" is the correct term.  Through error, it has become something else.
Answer: A "tough row to hoe" does in fact come from early American farming in days with limited machinery - in other words they used a hoe in the field to pull weeds from rows of crops.  It was hard work done by strong men in hot fields especially across the South.  In talking with my father who actually did some hoeing when he was a kid, he thinks the saying comes from the so-called "down row."  There was some equipment used in the field on certain crops which caused the furtherest row out to be damaged somewhat and knocked the crop down.  When hoeing, you work hard to pull weeds and not damage the crop itself.  So, when men hoed a field ther may be 15 or 20 workers all of which take a row which is theirs to hoe.  When the worker reaches the end of the row and has finished, they walk down to the next row that does not have a worker assigned to it.  The men wanted to avoid this so-called down row as they went to their next row becasue it was  -- you guessed it, "a tough row to hoe."
Frankly, it bothers me to hear the unknowing say "a tough road to hoe."  No one hoes roads other than convicts.  Men hoed crops.
Comment: But depending how you looked at it, hoeing a paved road would be either trivial (no weeds), or extremely hard (breaking asphalt with a hoe)
Answer: The expression appears to be American.  Frontiersman and Congressman, Davy Crockett (the "King of the Wild Frontier"), used the expression in his book, An Account of Col. Crockett's Tour to the North and Down East (1835).
The two earliest examples I could find are both from the same magazine in 1823, and suggest that the expression had already moved into idiomatic use by that time.  Although most of the early examples of the idiom I have found refer to a "hard" row to hoe, even the now more familiar "tough" row appeared in 1823:
"[I]t seems that the French have rather a tough row to hoe, and are likely to get more kicks than coppers, to pay for their toils and dangers in Spain." (Italics in original), New England Farmer, Volume 1, Number 48, June 28, 1823, page 383.
"Still the Greeks have a "hard row to hoe."  The Turks are collecting fresh armies, and threaten to overrun the Peninsula." The New England Farmer, Volume 1, Number 40, May 3, 1823, page 318.
Answer: I believe the road/hoe, and the road/hold sayings are the results of mishearing, or purposely changing the original row/hoe saying.  Similarly, on occasions, I have changed the expression "don't look a gift horse in the mouth" to "don't lick a sick horse in the mouth" just to get a laugh. However, we all know the original meaning.


Timer switch suggestions?

Question: I have a simple security/alarm system I built for my carport after a thief took advantage of me.
It simply has a strobe light and an extremely loud siren, using photoelectric sensors. When the sensors are tripped, the strobe and siren sound/light up.
What I want to do is turn the system off after about 5 minutes once tripped, then be able to engage itself again if need be. Any suggestions on a simple timer? This is a low voltage dc system.
Comment: 555 conected as monostable circuit - it needs about 1mF capacity to reach 5min time constant. Or 555 as astable with smaller time constant (about 0.85 sec) and inceased duration to 5min with counter IC (8bit). Reset at overflow.
Answer: A monostable multivibration with a time period of 5 min in the astable region should do the trick.
Answer:
Follow these instructions :

Change variable resistor( number 1 ) to 1 Mega-Ohm
It gives you 5 minuts ON-State then on delay and then it goes to OFF/State (in this state it will be ready for another trigger).

Your trigger is number 2 :
You can use a transistor instead of push button key.
Connect emitter and collector of your transistor instead of push-button's pins and you have to connect your command signal line to the base of this added transistor (i didn't about your output signal's voltage and i didn't design this part for you bur it's so easy and i think you can do it by yourself).

Connect a suitable relay instead of marked LED & resistor ( remember, you have to connect a common diode to your relay's coil in parallel but in inverse bias, it prevents fly-back surge voltage damage to you transistor and you must install it)

If something in this post wasn't clear for you, talk about it, i will explain more

Timer switch suggestions?


How to find the service pack level in ArcGIS Addin?

Question: I can query the current version from RuntimeInfo.Version. But I would also like to know what service pack is also installed. Do I need to just check the registery key HKEY_LOCAL_MACHINE\SOFTWARE\ESRI\ArcGIS\RealVersion. Or is there a proper ArcObject that allows such a thing?
Answer: This may be a better way then trying to read the registry key.
This page can be used as a lookup from version number to service pack.
<code>Process.GetCurrentProcess().MainModule.FileVersionInfo.FileVersion
</code>
Comment: +1 I guess we can safely assume build numbers always increase, so you can just compare to see if the build number you require against whatever the build number is in the FileVersion.
Comment: @KirkKuykendall That seems to be the case. The only thing I'm worried about is that the service packs don't update the executable version. I don't have any evidence that can happen, but I know that some DLLs don't always match...


What "how you might run the business if capital were free" even mean?

Question: I am reading "The hard thing about hard things" by Ben Horowitz, and there he mentions an advice from a venture capitalist who said, "Ben, think about how you might run the business if capital were free." what does "if capital were free" mean?
Comment: For a long time, capital has been essentially free.  It's not right now, and that explains why a lot of startups and publically traded growth-oriented companies are laying off employees.
Answer: Translation: "... If you could borrow money without having to pay interest."
Interesting as a thought experiment for exploring your priorities independent of practicalities, perhaps, which I assume is what the book is suggesting.
Answer: It's not completely clear without the full context, but here's my interpretation:
When a company has financial obligations, either to debtors or shareholders, it reduces the amount of risk they can take, since if they fail to pay that debt, they are in danger of going out of business completely.  It forces a business to invest in safer, more conservative, but lower return, projects for fear of being shut down.
If "capital were free", meaning you could borrow with no payments or raise money through equity without anything expected in return, you are free to invest in whatever projects you want, which frees managers to be more imaginative and risky without that fear of failure.

What “how you might run the business if capital were free” even mean?


restore notes iCloud IMAP

Question: I've deleted "notes" IMAP folder. Now I have no notes on Macbook, iPhone, iPad.
Please help me to restore my notes. I have TimeMachine backup.
Answer: Try restoring ~/Library/Containers/com.apple.Notes (I would keep a copy of the existing folder in case this causes other problems). That's where my Notes seem to be stored. If that doesn't work, you can dig out the individual files representing your Notes within that folder.
The directory structure of the com.apple.Notes folder is very odd. It seems to have aliases to things like my Desktop and Movies folders in it, for reasons that I completely do not understand. In any case, I found my IMAP Notes in ~Library/Containers/com.apple.Notes/Data/Library/CoreData/ExternalRecords/E7804A95-977C-4A1C-98A1-8C1D77E02D49/IMAPNote/_records/0/
Hope this helps!
Comment: Thanks! But after restoring, when I connect to the internet, all restored notes disappearing again :(
Comment: Hm. So I think you're going to have to copy and paste the text into new notes. You should just be able to open the relevant files from the Finder.

restore notes iCloud IMAP


Change image by Image Sequence in Shader Editor every nth frame

Question: I'm trying to make a video, where I'm using 40 images as an object color possibilities. But when I'm using Image Sequence, the image will change every next frame. But I would like to change each image every sixth frame. Nothing that I found here doesn't help me. Thanks for any information.
Answer: So I think I found a solution by keyframing the offset property.

0 at frame 1, 10 at frame 100 and it seems to be moving slowly enough.
Kind of a hack though.
Comment: [#KisKit](https://blender.stackexchange.com/users/39340/kiskit) has right. Everything is about playing with keyframing and offset and it works well. Thank you so much.
[![enter image description here](https://i.stack.imgur.com/fQLYU.jpg)](https://i.stack.imgur.com/fQLYU.jpg)


$x^3+ax+b=0$ has only one solution

Question: Let $a,b \in \mathbb{R}$ with $a>0$. Show that there exists only one $x \in \mathbb{R}$ so that $x^3+ax+b=0$.
Is it possible to prove this using the mean value theorem?
Answer: Since $f'(x)>0$ the given function is increasing, hence injective.
A cubic polynomial always has a real root, hence the claim is straightforward.
Answer: The derivative of the function is $3x^2+a$, Since the derivative is always positive the function is increasing and thus injective.
So it cannot repeat values, in particular it cannot have two roots.
Answer: Alternatively, the discriminant of a reduced cubic $x^3 + ax + b$ is $-4a^3 - 27b^2$, hence negative in this case. So from the three roots, two are complex conjugates and one is real (there is always at least one real root for a cubic with real coefficients).
Answer: let $f(x) = x^3 + ax+b$.

Existence
Since $\lim\limits_{x\to\pm\infty} f(x) = \pm\infty$ and $f(x)$ is continuous. By IVT, $f(x) = 0$ has at least one real root.
Uniqueness
For any $x > y$, we have
$$\begin{align}f(x)-f(y) &= (x-y)(x^2+xy+y^2 + a)\\
&= (x-y)\left(\left(x+\frac{y}{2}\right)^2 + \frac34 y^2 + a\right)\\
&\ge a(x-y) > 0
\end{align}
$$
So $f(x)$ is strictly increasing and $f(x) = 0$ has at most one real root.
Answer: Another alternative approach is using Descartes' rule of signs.
Case $1: b =0 $. Then clearly the equation has exactly one real root, namely $0$.
Case $2: b \neq 0$. As the degree of equation is odd therefore there exists at least one real root, say $x$. Suppose it has another real root $y \neq x$.
Then $$x^3 + ax + b=0 \\y^3+ay + b=0$$ This gives $$x^3 - y^3 +a(x-y) =0$$ This implies $x^2+y^2 +xy+a=0.$ This gives $$xy= -(x^2+y^2+a) <0$$ Thus $x$ and $y$ have different signs. Without loss of generality assume $x>0, y<0$.
Thus the equation has at least one positive and one negative root. Applying descartes rule of signs this gives a contradiction.
Answer: A solution using Rolle's Theorem is as follows:  Suppose $x^3+ax+b = 0$ has more than one real solution.  Call the solutions $a$ and $b$.  Then by Rolle's Theorem we know that $3x^2+a = 0$ for some $c$ in $(a,b)$, but with $a>0$ this is impossible.  Hence $x^3+ax+b$ cannot have more than one real solution.
Comment: (+1) Rolle's theorem is the standard approach for this kind of questions. So it is good there is atleast one answer using it.

$x^3+ax+b=0$ has only one solution


Any good online wallets?

Question: I've used a lot of online wallets: xapo, wirex, cryptopay, blockchain, etc. But recently these wallets have started to disappoint with their fees (xapo), transaction time (blockchain), rates (wirex) and complex verification. So I was wondering are there any new good wallets with reasonable fees and their own debit cards?
Answer: No. Basically no web wallet provides the level of control that many desktop wallets provide (e.g. coin control, fee control). Many of them are just exchanges and are custodial wallets so you don't really control the Bitcoin since you don't control the private keys.
I highly recommend that you avoid using web wallets as much as possible. If you do choose to use a web wallet, use one that is listed on bitcoin.org as those wallets have to meet certain criteria before being listed.
Comment: Thanks for participating to Bitcoin.SE, however please note that this question is off-topic as per the [help/on-topic] for being a software request. Off-topic questions can be closed and deleted, which would nullify your contribution! You can flag such questions for closure with the "flag" button.

Any good online wallets?


Why does the moon orbit the earth and not the sun instead?

Question: Objects orbit the sun because of the sun's gravity, and Earth's gravity is weaker than the sun's gravitational pull.  So why does the moon orbit the Earth instead of the sun?
Answer: The moon does orbit the sun but it also orbits the earth.  But your assertion that the earth's gravity is weaker than the sun's is not universally true.  If the sun's gravitational pull were greater than the earth's HERE on the earth, the sun would literally suck everything not attached to the earth's surface into itself.  Clearly that's not happening.
Remember that Newton's Law of Gravitation says that the force is inversely proportional to the SQUARE of the distance.  So while the sun does have a stronger gravitational pull, the distance that both we and the moon are at makes the earth's field dominate.
Answer: The sun's gravity is strong but the the earth overwhelms the sun's gravity ,and the moon is in the in the place where the earth's gravity overwhelms the sun's, so in short the moon orbit the earth because it is in the place where earth's gravity overwhelms the sun's


Both fuse and circuit breaker operated

Question: Is there a reason that both a fuse and a circuit breaker would operate? From my understanding, the fuse should blow first and kill any current flowing through it leaving the breaker intact. So why would a fuse blow, and then an upstream breaker trip and lock out?
Comment: If the current was high enough, both could possibly go together.  Fuses are thermal, but breakers can be magnetic and thermal.  The thermal breaker would be slower than the thermal fuse, which is why the breaker has a magnetic trip.  The current squared would be proportional to the magnetic field.
Answer: I would also think it unusual, most breakers have higher current ratings than that of products, but it really comes down to the details of the situation.
It depends on the fuse. There are slow blow fuses that take a few msec to blow, which could have been carrying a decent amount of current before the breaker shut off.
If the fuse rating was near the rating of the breaker, then the explanation is simple, the current rose and they both blew.
Most breakers have two mechanisms for tripping, one for a high fast magnetic current. And the other is slower and from heating an element in the breaker with current. Most fuses have an element that melts from ohmic heating and current. It depends on how much current for how long.
Answer: I've seen this effect in my microwave oven when the bulk plastic cap failed with reduced capacitance and leakage. 15A fuse and 15A breaker. (AFAIK)
It failed on surge startup and was repeatable. Its an unusual race condition that may be activated by the reactive load with arcing until fuse gap extinguishes the arc.

Both fuse and circuit breaker operated


Using Myhill-Nerode to prove a language is non-regular

Question: I'm trying to prove
<code>L={w∈{0,1}∗:w contains more 00 substrings than 11 substrings}
</code>
is a non regular language using Myhill-Nerode theorem.
I'm a bit lost and not sure what to do. Thanks
Comment: Hint: the prefixes  00, 000, and 0000 are distinguishable by different strings of 1's.
Answer: The basic idea here is that you are trying to show that there are infinitely many indistinguishable sets in $L$.
Distinguishable Strings: Let $L$ be a language over an alphabet $\sum$. We say that two strings $x$ and $y$ are distinguishable with respect to $L$ if there is a string $z$ such that $xz \in L$ and $yz \notin L$, or vice versa.  That is, if we append $z$ to $x$ and $y$, the machine that processes $xz$ will be in a different state than if it were to process $yz$.
An indistinguishable set is then a collection of strings that are indistinguishable from one another but distinguishable from every other indistinguishable set.
Consider a FA $M$ that accepts $L$ = { even 0s } with alphabet $\sum = \{0,1\}$.  The minimal FA for this machine has two states.  There exists an indistinguishable set for every state, one set containing odd number of 0s and one set containing even number of 0s.
For your language, consider that you have { 1 00 substrings, 0 11 substrings } $\ne$ { 2 00 substrings, 1 11 substrings } $\ne$ { 2 00 substrings, 0 11 substrings } $\ne$ { 3 00 substrings, 2 11 substrings } $\ne$ { 3 00 substrings, 1 11 substrings } $\ne$ ... $\ne$ { $k$ 00 substrings, $l$ 11 substrings | $k > l$ }. Each of these sets is distinguishable from other. In other words, your minimal FA would require infinitely many states due to its need for counting.  Since an FA cannot have infinitely many states, the language cannot be regular.
Answer: Myhill-Nerode theorem defines an equivalence relation $xRy$ when $\forall w, xw \in L$ iff $yw \in L$
Then it says that this relation $R$ partitions $L$ in a finite number of partitions iff $L$ is regular.
So what you have to do is to show that if $L$ is not regular then this relation partitions $L$ into infinite number of partitions. For this you need to specify infinitely many strings which are not equivalent according to $R$.
Here are more details, How to prove that a language is not regular.
Comment: This is more of a comment than an answer.
Comment: OP asked what to do, so I answered that, that is, the process. I could have added an example, but I thought there are lot of examples available. I will add a link to example.
Answer: Consider any relation R which on $\{0,1\}^*$ such that :

for any pair of strings $x, y$ related by $R$ we have, $xz, yz$ also related by $R$ (right congruence property)
any pair of strings $x, y$ are related by $R$ if either both $x, y$ are in $L$ or both are out of $L$ (refinement property)

Now if we have the property of finite index as well then by Myhill-Nerode theorem this will be a regular language, so to prove that this is not the case we should try to show that this doesn't have the finite index property:
consider 2 strings $a=(000)^n(11)^n$ and $b=(0000)^n(11)^n$ assume $a\ R\ b$ then by right congruence $(a1^n)\ R\ (b1^n)$ but $a1^n$ is not in $L$ but $b1^n$ is in $L$, therefore $R$ can not be of finite index, hence $L$ is non regular.


Is it possible to preload an image for the hero banner in Sitecore to improve LCP?

Question: We are trying to improve the LCP score of our site and one of the elements we want to optimize is the large image used in the hero banner of each page. Is there a way to set this image to be preloaded?
Answer: You can try below things to improve performance of page:

Use Dianoga tool for optimize images, you can read more about it on this link.
You can use jQuery lazy loader plugin.
Apply Sitecore cache on component.
Set height and width parameters on image.

You can refer this link as well to get more information Get Optimized Image in sitecore
Answer: Image preloading can be achieved by adding <link rel="preload"> with the URL of your LCP image to the  section of your HTML page:
<link rel="preload" href="/path/to/hero-banner.jpg" as="image">

The main difficulty is that typically a component with LCP image is rendered in the  of HTML page and <link rel="preload"> should be in the .
You can create a separate rendering and place it in the  section. This preload rendering will get the LCP image URL based on the context page and application-specific logic. The approach will depend on how your page is built.
For example, you have a product page and the LCP element on this page is the main product image that is defined in the product page item itself. In this case, the preload rendering can simply get the image field from the current product page and use its URL in the <link rel="preload"> element.
However, if you LCP image comes from a rendering with a separate data source (e.g. generic hero banner), you should either move the image field to the page template or write additional logic to retrieve the data source of this generic component.
Please note that if you implement preloading for LCP images, there is no point in having lazy-loading for them. The ultimate goal of LCP optimisation is to render the visible part of the page as quickly as possible, and lazy-loading will add unnecessary image rendering delay. So if you currently use image lazy-loading, consider disabling it only for LCP images to improve the largest contentful paint metric. Additional information can be found here.
Answer: Try to implement lazy loading hero images so that on page load all the images wont load and on scroll down each image gets loaded. By doing these we can reduce load time of images.
Answer: Try converting images to webP Images.
This will help to reduce the page load time for large size images.
Reference : https://anothersitecoreblog.wordpress.com/2021/03/03/serving-images-in-webp-format/
Comment: While conversion to webP may be helpful, it doesn't really answer OP question.


Is it allowed for an Islamic state to demand ransom from non-Muslims?

Question: Is it allowed by Islam for an Islamic state to demand ransom from non-Muslims to return others taken as prisoners? Do they need to be formally at war?
Answer: Quran mentions about ransom in the context of war. The following is the verse

So when you meet those who disbelieve [in battle], strike [their]
  necks until, when you have inflicted slaughter upon them, then secure
  their bonds, and either [confer] favor afterwards or ransom [them]
  until the war lays down its burdens.  Quran  47:4

As can be see in the verse, first option for captives of war is to free them by grace and second option being ransom for release of prisoners .The reason mentioned for ransom is for "war to lays down its burdens". This means Muslims are dragged onto a war by the disbelievers and it has cost Muslims wealth and lives due to this. So it is reasonable that prisoners are returned for ransom so that it pays for what costed the Muslims.
So to answer your Question, ransom is allowed for freeing prisoners of war. so yes, war is precondition for ransom.


Dreamweaver CS5 MAMP Site Definition Error

Question: Hi Stackoverflow world,
I need help! I have set up a development stack with MySQL/PHP using MAMP. I am trying to create a WordPress theme and have downloaded all of the files to htdocs in the MAMP file system. The server works great, when I type in my localhost into Firefox everything shows up as it should.  However, when I go to edit in DreamWeaver none of the files will dynamically connect. I am getting an error that says the site definition is not correct for this server. Here is what I have done within DreamWeaver and WordPress to try to remedy the issue:
1) wp-config: I have set up the database name, username, password, and host:
dbname: AmplifyFinancial
username: admin
Pword: ****
host: localhost

2) I have set up the site information in "manage sites".
Site
site name: AmplifyFinancial
local site folder: /Applications/MAMP/htdocs/wordpress

Servers
name: AmplifyFinancial
connect using: local/network
server folder: /Applications/MAMP/htdocs/wordpress
web url: "http://localhost/wordpress/"
remote box unchecked and Test box checked

testing server
server model: PHP MySQL

local info
web URL: "http://localhost/wordpress/"
links relative to: document
enable cache is checked

Even after checking this information literally 10 times, I cannot figure out why DreamWeaver is saying there is a site definition error.  I even tried changing the username and password information in the wp-config file to both say "root".  This did not work.  I have heard that sometime permalinks can screw things up, but I am not sure how to chance this to see if that is my problem.  Anybody have any ideas?  I am super stuck here....
Answer: You don't have to fill out the server, testing server and local info.. you can skip that part if you are just working locally.
And as far as the passwords go, that should be root / root


What is the quickest way to setup Dune: Imperium from DireWolf playing single, double or more players?

Question: I recently purchased Dune: Imperium to play with my family over Christmas.   What is the quickest way to setup the board game for single player or multiple players?  Is there a cheat sheet that provides easier entry to the setup or game play?
Answer: As with all my current "big' games, I would have set up the entire game once, including every player's starting components, then bagged them as individual sets before packing away the game.
The exceptions are general resources that have larger pools, which are kept together in their own bags, and  cards like the Leaders, which are ordered (you could choose alphabetically and/or complexity, especially if you expect to have new players for the foreseeable future).
All other decks are bagged separately, with the bags labelled to make repacking eaiser, so that they can be pulled out and shuffled and placed immediately. If you must bag decks together,

two decks: face to face, backs out, making separation easier

three or more: facing the same way, stacked in the order they would be placed by the board

The remaining tokens (Mentat, Factions) are bagged together.
When setting up to play, first put the board, decks and resources in the correct place according to the instructions (for solo/pair play, there is a separate sheet, or you might use the app to reduce effort on physical setup). Then, players choose their leader and a bag of individual components, and do their own setup.
This way, you only unpack the components you will definitely need, and they are not spread throughout the box. Following the rulebook requires slight adjustment as you complete the collective and individual setups separately. For example, the F1 step is left until individual setup, when each player picks up their own water in their own time.
There are benefits of this process for new players. They can help by unbagging and shuffling during collective setup, then mimic your individual setup afterward.
Comment: Unexpected. Thank you!  I do some of what you said, but not all.  This is great.


Oracle SOA client authentication by certificate

Question: Is it possible to configure Oracle SOA composite service for authentication by client certificate? For instance, we have Oracle composite service and WCF service. Composite service should be ensured that only clients with valid certificate have access. How does it should be configured?
Answer: You can configure 2-way SSL on weblogic server which hosts Oracle SOA suite. This ensures that only certified clients can make use of your service.
Other option is to use OWSM policies which can be configured for each service. Here is a good link to start with
http://docs.oracle.com/cd/E15523_01/integration.1111/e10226/soacompapp_secure.htm


BLE and Bluetooth Classic Coexistence?

Question: we are designing a fairly compact PCB for a communications device. We are looking at using BLE as a link for voice to a separate microphone, and BT Classic to be paired with a smartphone. We are using pre-certified modules, and they will located on the PCB about 20mm away from each other (can extend this to 40mm if need be). Is there a risk of interference between the 2? We are transmitting audio in both cases so interference would be particularly noticeably. They both operate at 2.4GHz, but I understand they have different frequency hopping techniques, and hoping this will allow for coexistence.
Comment: the absolute maximum throughput of BLE 4 is 12kbps (https://punchthrough.com/blog/posts/maximizing-ble-throughput-on-ios-and-android), which is pretty awful for audio (https://www.youtube.com/watch?v=53tdYmJuUmM)
Comment: BLE has rather low data rates, and is thus a poor choice for voice data. I strongly suggest looking at BT classic or other wireless protocol(s).
Comment: Actually BLE is capable of 2Mbps.
Comment: only ble 5, not ble 4.
Comment: BLE 5 could probably transmit audio, but the bigger issue is a lack of support from the Bluetooth organization. They would have to standardize the protocol for it to be useful on an iPhone or Android phone. So far it seems like they don't have any intention of doing that. You didn't explain any details about what the device was interfacing with. If it were talking to an OS, you'd be out of luck without Bluetooth Classic to provide the audio profile. If you had your own hub, you might be able to roll your own protocol with BLE.
Answer: They do not interfere with each other for most use cases. I've used them together in two different projects. I never had any issues.
Other people have pointed out that BLE might not be right for your application. I would definitely agree with them. With that aside though, for your more general question, yes you can definitely use them at the same time without worrying too much about interference.
When you use Classic and BLE at the same time, they complement each other. Typically, a product would use BLE for control. This results in the occasional transmission of small amounts of data. If a product integrated Classic as well, it would use Classic to transmit large amounts of data at a higher throughput. The device would see-saw back and forth between the two stacks. In that situation, they wouldn't interfere with each other. If you tried to transmit large amounts of data through both channels at the same time, that might result in poor performance for more reasons than just a shared frequency spectrum. They would also share the same antenna and processor.
Both stacks use some shared resources to keep the links alive, but Bluetooth doesn't require much to maintain connections by design.
Answer: They are both 2.4GHz, but BLE uses an adaptive frequency (channel) hopping algorithm to avoid congested parts of the the spectrum, so at least BLE should tolerate Classic. Not sure about the other way around. Presumably it should be fine because BLE will avoid Classic to the benefit of both.
As for audio, it's all digitized by the time you are in Bluetooth, so you won't get degradation in quality, but maybe dropouts.

BLE and Bluetooth Classic Coexistence?


Terminology for contracts in multiple Languages

Question: My company is having contracts drafted in both English and Japanese and we want to have the English version take priority over the Japanese. Is there a specific legal term for this structure?
Answer: I don't know of a specific legal term but such clauses are quite common in contracts which consist of more than one document. The English words "priority", "prevail" and "precedence" have the meaning you want, however, "precedence" runs the risk of being confused with "precedent" which does have a very specific legal meaning.
A clause similar to:
If there is any inconsistency or ambiguity between the English and Japanese language versions of the contract, the English version shall prevail.
You need to make very sure that this clause can be translated unambiguously into Japanese!
Comment: Thanks, I'm surprised there isn't  a specific term for this
Comment: @CharlesHoskinson I didn't say there wasn't; just that I didn't know of one.


Why do the ailerons on an A320 droop when the engines are shut off and the 787 ailerons dont droop when the engines are shut off?

Question: I have been wondering why the ailerons on the A320 (and other Airbus aircraft) droop when there is no power from the hydraulic pump. From my understanding of hydraulic actuators, the position where it was before the pump was shut off, is where it is gonna stay (if that makes sense) because you are closing the fluid intake and outake valves. I think I understand how Boeing actuators work, and why they stay in place with no hydraulic power coming from the pump. Just why do these Airbus ailerons droop with no hydraulic power?
Comment: ASE is visited by many new English speakers (since English is the language of aviation) -- perhaps consider replacing "gonna" w/ -- ??
Answer: The A320 aileron actuators have servo valves of course, which when closed indeed allow no flow through them from pressure to return. They additionally have mode valves, which do provide a direct (damped and narrow) connection, and it is this connection that allows for a slow and smooth aileron droop when unpowered.

Pic above is from this site, which contains a thorough explanation and simulation of the actuator. The right hand side is the valve in stand-by mode,

In active mode, the mode valve establishes connection between the servo valve control ports and the cylinder ports enabling nominal functioning of the system. In stand-by mode, the mode valve isolates the control ports of the servo valve and connects both cylinder chambers through a damping orifice and anti-cavitation valves – refilling the chambers in case the pressure goes below return pressure.

@JohnK added a valuable comment: the main reason to do this is, when the hydraulic system is unpressurised there is passive flutter damping...

...meaning fewer or no dedicated passive flutter dampers are required for that surface than if you have actuators that hydraulically lock with no pressure present and no spool valve displacement from a control input.
Comment: You could add that the main reason to do this is you can take credit for the actuator's idling circuit in providing passive flutter damping if its hydraulic system is unpressurized, meaning fewer or no dedicated passive flutter dampers are required for that surface than if you have actuators that hydraulically lock with no pressure present and no spool valve displacement from a control input.


Is there any way to get a meteorite if there's no Corruption or Crimson in the world?

Question: What do I do if my world has no corruption or crimson whatsoever? Is there any other way to have meteorite fall?
Comment: Every world should have either corruption or crimson (not both) in it somewhere.  Make sure you explore from ocean-to-ocean before discounting any existing on your map.  Some worlds have multiples on both sides of spawn, others have very little.
Answer: If your world doesn't have either, someone probably cleansed it all so look for chasms with stone walls. You should be able to find crimson hearts or shadow orbs at the bottom to get a meteor to spawn. If you really can't find anything that even looks like it was corrupted before, you cannot get a meteor to spawn. I would check with a map editor to be sure, though, before generating a new world.
Answer: Just to double check, you should download a map editor or viewer like terrafirma to make sure you don't have any corruption or crimson. After you have checked and there has been no sign of the previously stated biomes then you either must look for terrain that looks similar to the biomes and explore there (If lady luck is smiling at you, you will find either a shadow orb or a heart) or make a new world entirely. Sadly, there is no other way to summon a meteorite :(
Answer: If your ultimate goal is just to farm the ore, you could import 50 meteorite ore from another world and place it anywhere you like.  This will cause Meteor Heads to spawn, which can drop ore.  Just make sure it is all kept in the same area (on one screen).  You will know you've done it right when the Meteorite Biome music starts to play.
Answer: Meteors do not require destroying shadow orbs to spawn. This is just the most efficient method for getting a meteor to spawn. There is a small random chance that every sunset a meteor will come crashing down.
Comment: The small random chance only appears after you break the first orb/heart.
Comment: Ah, I though there was always a chance.


Claiming honours in rubber bridge

Question: When playing rubber bridge, can the declarer still claim after the hand is over but the next hand has not been dealt?
Answer: From the 2014 Laws of Rubber Bridge:

Law 76 - Responsibility for the Score
....  Honors may be claimed until the next hand has been dealt, or the
rubber has been completed and scored - whichever comes sooner.

and

Law 78 Correction of the Score
When it is acknowledged by a majority of the players that a scoring error was made in recording an
agreed upon result (e.g. failure to enter honors or incorrect
computation of score), the error must be corrected if discovered
before the net score for the rubber has been agreed to. However,
except with the consent of all four players, an erroneous agreement as
to the number of tricks won by each side may not be corrected after
all players have called on the next deal.
In case of disagreement
between two scores kept, the recollection of the majority of the
players as to the facts governs.

Claiming honours in rubber bridge


Rails 3.1 sortable nested set with jquery and two models

Question: Here is my issue, I hope someone can point me in the right direction.  I am wanting to utilize drag and drop to create a dynamic catering/restaurant menu.  I would like to create a view that I can add Sections and then add MenuItems to that section (and possible subsections).  I understand fairly easily how I can accomplish this with one model,  but I would like to keep sections and menu items in separate models.  How would I go about setting up the sortable nested set gem  to use dual models?  Should I rethink and use one model?  Any guidance would be greatly appreciated.
Answer: It is easier if you use one model.
The menu item approach seems to be nice. You can write active_record callbacks to add and remove sections/catering/restaurant to and from the menu items model.
GUI for a nested_set gem
https://github.com/the-teacher/the_sortable_tree


Dating very old objects/events

Question: After reading this space timeline, I have wondered how they managed to make these assumptions about various events like when the first black holes formed. This is obviously far beyond the good ol' carbon-14 dating procedure.
Answer: One property of distant objects, that follows from the limited speed of light, is that we are observing them in the past; the light that they emit takes time to reach us. For very distant objects, we are effectively observing the universe at a very early time.
Objects that are very far away, such as distant galaxies, are receding away from us, which causes the light that they emit to be doppler shifted. The recession velocity is proportional to the distance away, and in turn so is the magnitude of the redshift. This redshift allows us to put a number to the distance away; combining this with the speed of light limit allows us to determine how old the light we are observing from them is.
These two effects, the limited speed of light and redshift, effectively allow us to determine an evolutionary timeline for the universe, and place constraints on when certain objects appear.
Comment: You're right Rob, updated now to distinguish between carbon based and other radiometric dating techniues
Comment: Still wrong. Radiometric techniques can be used to date stuff that is found in the solar system (presolar grains) that is older than the solar system. Radioisotope dating has also been used on other stars.
Comment: Given that I evidently don't know enough about radiometric techniques to comment on them, I've removed the first paragraph completely. The subsequent arguments address the theme of the OP's question
Answer:
I have wondered how they managed to make these assumptions about various events like when the first black holes form.

When the first black holes formed ( and many other things ) are things we predict from theoretical models of the development of the universe.  They are no proven facts, but better classed as speculative predictions based on theories.  Different theories give different predictions.
The way it works ( broadly ) is this : We try and develop theoretical models of the universe's creation and early development that will develop into a universe that matches what ours looks like.  Doing this has led to such controversial concepts as string theory, which are not proven facts in a scientific sense, but theories subject to ongoing investigation.
We try and verify ( or disprove ) theories by comparing what they predicts with what we see.
So these "histories" should be considered as "best guesses" to some extent.
The approximate date of the Sun's formation, for example, is based on our current best models for the evolution of stellar bodies like the sun, which of course are based on our current best measurements of whatever we can measure in relation to it.
For history related to objects we can examine in more detail, like stuff on Earth, some of which came from space, we can perform detailed analysis and look for patterns in related objects and areas.  This makes estimates dating from the start of life on Earth on reasonably good.
So the far distant history beyond that is concerned we're relying primarily on models driven by astronomical observations and the law of physics we regard as "safe".
Comment: The age of the solar system is general thought accurate, but is subject to constant revision, as we simply do not know.  It is what is considered most likely based on current evidence, not "very accurate".  Physics has a different idea of what is "very accurate" than you seem to be using.  Models of the sun vary in purpose and scope, but formation models are based on known physics and attempt to fit to what we understand.  All models tend to work that way.  Observation of black holes in inferred, not direct.
Comment: The "first black holes" business comes from observation, not from theory. In fact theory is struggling to explain how they could form so quickly. The age of the solar system is based on radioisotope dating in meteorites and is very accurate. Models for the evolution of the Sun are *tuned* to match this age.
Comment: It is simply incorrect that the age of the solar system is "based on our current best models for the evolution of stellar bodies like the sun". The age of the solar system is known to about 1 million years (1 part in 4500) from radioisotope dating.

Dating very old objects/events


How to merge folders with different letter cases into one?

Question: Nautilus doesn't merge folders with the same name if one of them has uppercase letters and the other doesn't; if one is called "Folder" and the other is called "folder" then Nautilus wouldn't merge them. I have a large amount of files that I need to merge, is there a script that would allow Nautilus to mass merge them all? If not, is there another way than manually renaming all the folders?
Answer:
It is by design. File and folder names are case-sensitive in *nix systems.

Renaming can be automated in a variety of ways.  Mass renaming utilities are available, pyrenamer ,
nautilus-renamer  ,
rename,
 mmv  , to quote a few.
To complete the answer, here is a script that does the renaming for you.
rename 'y/A-Z/a-z/' *
This should rename all files/folders to lowercase.
Answer: NO, you can't simply merge them.
In any Linux or Unix (including Ubuntu), filenames and folder names are case sensitive.  So two similar directories but with different case can co-exist.
You need to create a shell script to rename them ..
( I will see if I can find the time to write one. )


Access Time Capsule from Android phone

Question: Can I access the contents of the "Data" folder on computers other than Macs? For instance, can I access the Time Capsule from my Android phone?
Answer: What do you mean by "access"? If you mean editing files and/or copying files to and from Time Capsule, you might not be able to do that since the hard drive in Time Capsule is formatted using Mac Journaled file system. If all you want is to view files, some Android apps might be able to access the device over network.
Comment: Access as in be able to copy stuff from the time capsule to the phone. Basically use it as any other NAS
Answer: The Time Capsule (and external disks connected to an Airport) supports AFP and SMB protocols. If your device supports either of these you can access the HD.
Answer: access the time capsule - easy. load file manager hd ( play stor - free) and use the menu to create a new lan  connection. top menu in upper left / network / create. input details and you're done.
Answer: use x-plore app to acces files on time capsule hdd

Access Time Capsule from Android phone