Why doesn't my house get misty?

Question: When there's dense mist/fog outside and I open a window, why doesn't the inside of my house fill with mist?
Comment: I don't have time to go into all of the details, I expect someone else will get to it later, but there certainly can be fog/clouds inside.  An artist named Berndnaut Smilde has used this to great effect: http://www.booooooom.com/2012/06/09/artist-berndnaut-smilde-makes-real-clouds-appear-inside-gallery/
Comment: @Adam: Berndnaut Smilde creates fog with a fog machine. I'm really excited. ;-D
Comment: @AdamRedwine Oh, I know there CAN be clouds inside - large buildings can have their own weather systems! But if I open my windows when there's dense fog outside, I don't notice my house becoming foggy.
Comment: *Part* of the explanation is an observer bias. You can't see fog except by looking through a lot of it, so unless your house is very large or the fog is *extremely* dense, you wouldn't be able to see much of it inside anyway. The rest of the physics is explained in the answers below.
Answer: It's a matter of temperature and dew point. If it's foggy outside, that means the temperature outside is at or below the dew point. Chances are it's warmer inside your house. If so, no fog.
On the other hand, if the temperature inside is the same as outside, it may actually be foggy inside, but you don't notice because sight lines inside may not be long enough to notice the fog.
P.S. Dew point is the temperature at which the rate of condensation of water vapor into droplets (releasing heat) equals the rate of evaporation of droplets into vapor (absorbing heat). It depends, of course, on the amount of water vapor in the air.
Comment: Fog forms on warm (wet) surfaces with colder air above it, but will only remain if its not to windy. So fog will probably not form inside a house. And due to the lack of wind it will probably also be hard for the fog to be blown inside the house.
Comment: @fibonatic presumably fog should diffuse into a building that has the right conditions to support fog, so wind isn't necessary to move it
Answer: The fog evaporates when it enters your house.  If you want fog in your house, you should try filling it with a couple of inches of water so that the interior is at 100% humidity.
Your house, and most other places, are unlikely to be at 100% humidity because they're not soaking wet.  If not, dew will condense on anything that's cold, and the water will run off, probably to somewhere inaccessible.  When the temperature rises again, that water will no longer be available to evaporate, so the humidity will be below 100%.
So,suppose your humidity is below 100%.  When fog blows in, you will mix the 100% humidity air at Toutside around the fog with the X% humidity air at Tinside in your house.  If your house is enough colder than the air outside, it's possible that the humidity will be over 100% at Tmix and even more fog will condense out of the air.  Chances are, though, that your house is either the same temperature or warmer than the air outside.
So, now you have fog droplets at (50 + X/2)% humidity, let's say, where equal parts of inside and outside air have mixed.  The fog will evaporate into the air, or at least some of it will.  But if these fog droplets last for long enough, you'll still see them in your house.  How long will they last?
Fixed the part below about how long it will last.
Droplets turn out to have an evaporation rate that is nearly constant:
dD^2 / dt = -K

where K depends linearly on the partial pressure of water that you could still add to the air before it's at saturation, and D is the diameter.  In "Kinetics and evaporation
of water drops in air" by H.J. Holterman (IMAG report 2003 – 12, Wageningen UR, July 2003), Table 4, we see that K is a constant of about 100 μm2/s at 90% humidity and 15C.  (And even if that were after mixing that would mean your house is incredibly humid.)
Since typical cloud/fog droplets are only 10-20 microns in diameter, even under these very humid conditions, most droplets will last no more than about 1-4 seconds.  With more typical humidity, they'd last a fraction of a second, which means that the lifetime of the droplets would be dominated by the time taken for the outside and inside air to mix, not the evaporation of droplets in mixed air.  So to get a noticeable amount of fog inside a livable house, you'd have to have a decent breeze, and then mostly what you'd see is droplets in air that had not yet warmed up or mixed with the air inside.  Fog normally forms in calmer conditions, but maybe in San Francisco where fog blows in with a decent breeze you'd have a chance at seeing some indoor fog.
Comment: This equation does not apply for droplets, where diameter plays a crucial role (google "droplet evaporation"). Furthermore, you are assuming cold and humid within the house. This does not help with the answer of this question because then you can construct a situation in which the fog droplets do not evaporate at all. For realistic situations, you will get an evaporation time of the order of 1 s.
Comment: @Aziraphale - The geometry plays a larger factor than I'd anticipated, so this answer is wrong, but not for the reasons you stated.  Diameter already does play a crucial role in this answer; it's just the wrong role.  Of course I'm assuming the house is cold and humid, as I was trying for a scenario where you would be at the border between seeing something and not.  Understanding where the border lies between two qualitatively different phenomena is one of the best ways to understand why you do/do not see something under a particular circumstance.
Answer: Fog / clouds form when the air temperature drops below dew point. The dew point is the temperature at which 100 % relative humidity is reached. At and below dew point, condensation exceeds evaporation at the condensation nuclei, and droplets can survive.
There are several ways to decrease the temperature of a given air mass:
Decrease air pressure by vertical motion to create clouds, move air into a colder environment to create advective fog (or go outside in winter and breathe), let moist air stay still in a depressed area over night to create radiative fog.
On the other hand, and to answer the question, if an air mass is heated (e.g. by entering the inside of a house), evaporation of the droplets exceeds condensation and the fog will disappear.

Why doesn't my house get misty?


How to perform upload bandwidth test with youtube before live stream?

Question: I understand that it is recommended to perform a bandwidth test before starting a youtube live stream. So that we can select appropriate encode parameters for the stream.
I do know that there are hundreds of services which allow you to perform a bandwidth test(OOKLA, Bandwidthplace etc.) using a browser.
My software runs on an embedded device and I have to do the bandwidth test programmatically, without user intervention.
Currently I have deployed a TCP server which reads and discards data on AWS. I have developed a small bandwidth test client running on my embedded device, which sends data to my server and calculates the bandwidth.
As my bandwidth test is with some other server. The bandwidth that I calculate may not be same as the upload bandwidth I will get with YouTube.
Questions:
1. Is there a service offered by YouTube to check my upload bandwidth before starting live stream ?
2. Are there any better approaches where I can get a good estimate of the current upload bandwidth ?
Answer: Just start a "test" live stream and see how it works. Anything else will just be a very rough approximation of the real use case.


Is there any logic in the teammatching?

Question: Well, as the title says: is there any logic at all in the teammatching of Splatoon? Is it based on previous rounds, armor, weapon, level? Of course in ranked mode you'll be put with 7 people that have roughly your rank, but what decides in what team we play?
Answer: According to Jintor (who translated this site) the matchmaking is based on your playstyle. You are matched against people that have the similar playstyle as you have. This playstyle is determined by the kills/deatchs and area you have painted.

According to the explanation, "regular match" doesn't take into account the closeness of your ranks, but rather the similarity of one's playstyle. Rank is a measure of the amount of time that you've played; in direct matching its influence is negligible.
In other words, people who focus only on improving their kill count will largely be matched against other people like them. In short, kill count, death counts and paint points are the three criteria by which matchmaking is accurately assessed.
Initially, we wanted to make ranks vaguely map to the match-making criteria (?) but gradually began to feel that it just wasn't working. At last, we solved the mystery.
Of course it's not a perfect system, so once in a while players might notice and think "I've been ranked here?", but hopefully players will come to the realisation that they've been assuredly put into the same category as like-minded players (lol).
Comment: Well, it doesn't explain with whom you are matched, but *against* whom.
Comment: If this is what they were going for, their algorithm could use some work. One match, all three of my teammates combined got 0 kills and less than 400 paint points. Combined. With no leeches or disconnects. I had something like 1,200 points, 6 kills, 1 death, and a lot of disappointment with my team.
Comment: @Mathias711 presumably, the game finds the best pairs (ie, x vs y) and then randomly assigns them each to opposite teams, meaning you have one foe that you're matched against, the rest is just random.
Comment: @Brian worth noting that they're matching playstyle, not skill. Would be nice if they sorted at least a little on that as well - bit disheartening to be matched 13-12-8-7 vs 20-20-20-20.
Comment: Level 20 is not saying anything at all about skill. It does about playtime.
Comment: @Mathias711 Also points to experience and access to weaponry. It's not the most fun to get kicked around the block by a gun you can't have yet. :)

Is there any logic in the teammatching?


Jenkins Pipeline - How to upload folder to S3?

Question: I have, as I think, simple use case, when jenkins builds static website, so in the end of the build, I have a folder like $WORKSPACE/site-result.
Now I want to upload this folder to S3 (and clean bucket if something already there). How can I do it?
I'm using pipeline, but can switch to freestyle project if necessary. So far I installed S3 Plugin (S3 publisher plugin). Created IAM user. Added credentials to "Configure system" section. And can't find any further info. Thanks!
Answer: If the answer suggesting the Pipeline AWS Plugin doesn't work, you could always have an upload step in your pipeline where you use sh call the AWS CLI:
aws s3 cp $WORKSPACE/site-result s3://your/bucket --recursive --include "*"
Source: http://docs.aws.amazon.com/cli/latest/reference/s3/
Comment: Hi I have a similar use case,
Answer: You have to use s3Upload plugin and set the sourceFile parameter as '*/*'


disable button on masterpage .net 4.0 (c#)

Question: Im trying to disable a button on the masterpage from a content page when certain criteria are met.
I can change the text on masterpage buttons using session variables, but IM having a bit of trouble with this latest bit - any hints anyone?
Comment: Are you trying to do this in the code behind after postback to the server, or are you trying to do it on the client through Javascript?
Comment: Is this ASP.NET or ASP.NET MVC?
Answer: I would add a public method to your master page that does this, and let the content page call it. This can make things a lot easier and more object-oriented.
You can use the MasterType directive in the content page to strongly type the master page. This will make it easier to call your method.
<%@ MasterType virtualpath="~/Masters/Master1.master" %>

Answer: On your Master Page you would have a public function like so:
public void EnableTheButton(Boolean enable) {
  btnTheButton.Enabled = enable;
}

On your content page you would write:
((MyMasterType)this.Master).EnableTheButton(false);

Comment: This worked fine, I know there are rights and wrongs in these things but Im just starting out really with c# so was looking for something simple - this suited me fine thanks
Answer: This is a common problem that comes up from many people, and there is a really "easy" way to make it work. However, if you plan on this application growing or being significantly complex, taking the easy way out will hurt you. Most of the other answers are going to tell you about the easy way. Let's at least discuss the right way.
First, let's be clear on the relationship between master and content pages. A content page should not directly invoke implementation-specific members on its master, or vice versa. They are separated by the Page-Master contract. What's happening at a logical level? Something is happening on the content page that should result in a specific button being disabled.
Now, since the button is on the master page, it should not be aware of the specific content page. So it should also not be the button's responsibility to call down to the page instance and check for the criteria, nor should it explicitly subscribe to a type-specific event.
So what to do? There should be some master data object (probably a singleton) that lives in a centrally available location across the request lifetime. Say, HttpContext.Items or Session. Being a master data object, it should be the single authority for managing these conditions you're talking about. It should raise an event when any of the data is changed, and anyone (such as your button) can subscribe to that event and make decisions based on the state. (Sample below)
If your app will be stupid-simple, then this is definitely overkill. But as you grow as a developer, and start to build more sophisticated systems, these are things you need to keep in mind to keep your apps simpler, more stable, and more maintainable.
Here's two concrete, real-world things this approach addresses, that come from my experience.

This one's pretty straightforward - if you need to swap out masterpages at runtime, you want to decouple your page and masterpage implementations completely. One masterpage might have things another doesn't. One specific case of mine is a bit extreme - we have dozens of masterpages nested up to 6 layers deep, swapping them in and out at runtime. But the principle of flexibility remains the same - look at how many questions there are on this site for how to change the masterpage at runtime!
This one's a little more heady, but still has very practical consequences. Breaking logical responsibilities into separate classes has one very important effect - it typically reduces the total number of logic branches (e.g. if statements) in your applications. Those are the single biggest source of bugs. If a class doesn't have any logic, it's pretty hard for it to have bugs! :) When you start to think about applications in terms of man-years and development staff over time, and measure in hundreds of thousands or millions of lines of code - fewer logic branches aggregated over the whole application has a real, measurable impact on stability and changeability. Maintenance and enhancements become more about arranging simple, stable components than doing code surgery.

Here's the example masterdata class:
public class MasterData
{
    private string _state1;

    public string State1
    {
        get { return _state1; }
        set
        {
            _state1 = value;
            OnDataChanged();
        }
    }

    private string _state2;

    public string State2
    {
        get { return _state2; }
        set
        {
            _state2 = value;
            OnDataChanged();
        }
    }

    public event EventHandler DataChanged;

    private void OnDataChanged()
    {
        if(this.DataChanged != null)
        {
            OnDataChanged(this, EventArgs.Empty);
        }
    }
}

Comment: Other than appealing to your sense of design, can you enumerate real-world problems with calling a method on the master page? I've used this approach quite a bit and it has served me well.
Comment: @Jonathan sure - I added two to the answer.


Usage of a or one, when to use what

Question: It's a simple but stupid question, I don't really know when to use "a" and "one" like.
One chance or a chance.
One way or a way.
What's the difference or there isn't any?
Answer: That's not a stupid question, because there are cases where either could be correct but the usage depends on context, intent, and emphasis.
"One" can indicate that it's solitary and final.

There is (only) one solution to this problem. Solve it, or we all die!
There is (only) one way out of the maze. Find it, or we all die!
You have (only) one chance to save the day. Do it now, or we all die!

OR, "one" could indicate that the speaker doesn't think it's the best of all available options ...

True, that is one way to solve the problem, but if we don't want to all die, this might be a better option ...
This is one way to get off the mountain, but we should keep searching for a safer route.

"A" can indicate that there are other known/likely alternatives:

This is a solution to the problem - it's not the cheapest or most elegant option, but it works!
Here is a way down the mountain, or we could ski over to that other one instead.
This is a chance to talk to that girl you like, but you'll have another opportunity next week too.

You can also use "a" to refer to the one option remaining if you thought you were out of options.

There's still a chance to save the day! I didn't see that coming!
Here's a secret passage leading out of the cave we were trapped in! We're saved!

If you're simply asking for an object, using "one" or "a" depends whether you care about how many objects you receive.

Please give me a hammer (because of course I only need 1. If I needed more I would ask for a specific number).
Please give me one (and only one) nail.
Answer: The obvious difference is that of implying future intention - If I give you one chance I'm implying you will get only one chance. If I give you a chance, it doesn't provide the same restriction of intent in that I could give you another chance at a later stage.
Comment: On the other hand "There's _one_ way [of solving this problem]" could mean a new way that the speaker has just thought of, rather than the only way. It's not a stupid question at all if you speak a language where the indefinite article is the same as the number one. It's really difficult to formulate a rule for the distinction in English.
Answer: One is a quantifier. Before a noun it specifies how many of that noun the speaker is  talking about:

I know one way to get to Hong Kong, and that way is to fly.

There may be more than one way to get to Hong Kong; indeed the speaker may know more than one way; but the speaker is talking about a certain quantity of ways to get to Hong Kong, and that quantity is one. Not two, not three, not 101 but one.
A/an is the indefinite pronoun. It evolved from The Old English word meaning one, so it's no wonder they often are very close in meaning. You use the indefinite article to make an indefinite noun phrase, as in

I know a way to get to Hong Kong, and that way is to fly.

The simplest thing to say is that the speaker is not giving us a quantity. Yes, a way is equivalent in number to one way (Note again that a/an evolved from one) but a quantifier and the indefinite article do not mean the same as far as the speaker's assumption or intention. An indefinite noun phrase is most often used when the speaker does not assume that his hearer can identify which thing he is talking about or does not care whether the hearer can identify it.
Let's try a different sentence to make that clearer:

A: I know a way to get to Hong Kong.
B: What is it?
A: It is to pay this 77-year-old ex-monk named Chan to take us at night by boat.

When A says a way to get to Hong Kong, he does not assume B knows which way that A is talking about. And that assumption is likely correct, since B has never heard of this way before.
Another example. There is a guy (called Joe) who wants a hammer. There are seven hammers on the shelf top.

Bring me one hammer.

The speaker, Joe,  is asking for the quantity of one when it comes to number of hammers. One hammer, not two or three or seven. One is all I want.
But if Joe says

Bring me a hammer.

Grammatically, this means he doesn't care which hammer he gets. It can be any of the seven hammers on the shelf. It is similar to saying any hammer. It's  true that a hammer in this context is equivalent to the quantity of one hammer, but that is not what a hammer means, and ultimately the difference in meaning is why there is both one and an in modern English. A hammer means 'I don't expect you to be able to identify which hammer I have in mind'  or 'I don't care which hammer you bring me'.
At the risk of confusing you, let me also say that Joe can say:

I don't care which hammer you bring me. Bring me one of them.

Joe is talking about quantity.
Joe can say

I don't care which hammer you bring. Bring me any one of them.

Here Joe is talking about quantity (one) and being indefinite (any). He wants any one hammer. In older times, he might have said 'Bring me an one of them,' but that's not standard today. Also notice that any comes from the same Old English word as one.

Usage of a or one, when to use what


The shape of a crest and a trough on wave

Question: what is the  significance of the shape of a crest. For example, in the figure below, we can see that one graph of sound pressure shows sharp crests while the other shows smooth crests. How does this affect the sound quality or any other quality?
To be clarify, the graph with sharp crests is from a steel plate oscillating while the one with smooth crests is from a aluminium plate.
Answer: The lower plot would have almost all of its energy concentrated at one frequency and its sound would be a pure clean tone at that frequency.  Whereas the upper plots would have higher frequencies in addition to the 'center' frequency and its sound would not be pure but would be slightly distorted from a pure tone. These harmonics could have a variety of undesirable effects: sound quality degradation, noise generation, heating loss, power loss, etc...
Comment: ...For some definitions of "pure" and "clean" and "distorted." There are some sounds (e.g., the sound of a bell, the sound of a plucked acoustic guitar string) which can have rich harmonic content, but which most people would not describe as "dirty" or "distorted."
Comment: True--edited my answer.
Answer: A single frequency has a distinct mathematical shape function, sin(wt-kx).  This is a smooth function.  These are also solutions to the wave equations so any solution, e.g. phenomenon, can be described by a suitable expansion or superposition in terms of sine functions with different frequency, w, and/or wave number, k.  The lower curve "looks" closer to  pure sine wave but that doesn't mean it really is pure.  In contrast the upper one has, as you mentioned, sharp jagged peaks and appears to have a higher frequency to these jagged peaks.  This could be a couple of things and you haven't really provided enough data to determine what it is.  While it may be safe to say there are some higher frequencies contributing to the plot the cause is not obvious.
It could be higher harmonics of the plate excited by how the plate was set in motion.  Did you strike it with a hammer, or drive it with a piston placed on the plate?
It could be random noise, white Gaussian noise in the detector used to gather data.
It could be a sampling artifact although you claim to have the same frequency in both.  It would help to know what that frequency is, e.g. the driving frequency or resonance frequency of each plate.  If the former then identical plates made from different materials would have different harmonics and the Aluminum plate may be tuned to the driver while the steel is not tuned and hence exhibiting some combination of modes superimposed on the driving frequency.
It could be ringing of the plate against some other component of the system.  There could by some part of the experiential set up that is not controlled.
There could be a defect in the steel, a crack or something causing rubbing that shows up as noise.
To know what it is it would help to perform an FFT on the time series data and look at the spectrum.  The true harmonics of each plate are predictable using simple formulae.  Noise would show up with a uniform distribution in frequency.
As for the effect of quality of sound.  If the peaks are due to harmonics it would not necessarily be "dirty", it may be bright.  Typically a pure tone sounds dull to the human ear.  The more higher harmonics there are in the spectrum the "brighter" the sound is.  You would get this from a guitar by plucking the string closer to the bridge.  Whereas plucking closer to the center you get a spectrum more like the bottom plot.  If it's noise then it will sound dirty or raspy.  However I would not venture to correlate any of these terms just by looking at the time series data alone.  If you did the same experiment with two aluminum plates struck differently you would get different results.  The steel also seems to have a large starting amplitude which implies a percussive strike in addition to being driven.


Capture normal (stdout) output along with error (stderr) output

Question: There is a script run via cron with the following line:
0 * * * * (/var/script.sh | tee -a /var/script.log)

How do I rewrite the cron entry to capture both normal stdout and error stderr output? They are to be placed in different files.
Comment: @glennjackman Could you extend your comment to an answer, please. So it could also cover redirecting `stderr` output to the file.
Answer: cron jobs are run by sh by default, and regardless of whether sh is a Bourne or POSIX sh or compatible, the syntax would be:
0 * * * * /var/script.sh 2>&1 | tee -a /var/script.log

Where the | causes the two commands on either side to be run in parallel connected with a pipe with the stdout (fd 1) of the left one plugged to the writing end of the pipe and the stdin (fd 0) of the right one plugged to the reading end.
By adding 2>&1 to the left one, we have the fd 2 (stderr) point to the same resource as pointed out by fd 1: the writing end of the pipe, so both the normal and error output of script.sh will go to the pipe to tee.
tee will write it both to its stdout (which in the case of a cron job is either a pipe or temp file that will be used to send an email to the user) and to script.log.
That syntax also works in the fish shell.
With (t)csh, zsh or bash (4.0 or newer), you can also do:
SHELL=/bin/zsh # or tcsh, bash ...
0 * * * * /var/script.sh |& tee -a /var/script.log

(where SHELL=/bin/zsh is how you tell cron to use a different shell to interpret the command lines).
In fish, you'd use &| instead of |&.
With rc (the once to be successor of sh) or derivatives, the syntax is:
SHELL=/bin/rc # or es, akanga
0 * * * * /var/script.sh >[2=1] | tee -a /var/script.log

With zsh, you can also do without tee  thanks to its MULT_IOS feature:
SHELL=/bin/zsh
0 * * * * /var/script.sh >&1 2>&2 >>& /var/script.log

Which would also have the benefit of preserving script.sh's exit status, and also keeps script.sh's stderr going to the original stderr in addition to script.log (though that doesn't make much of a difference in a cron job where stdout and stderr generally go to the same place anyway).
A few Bourne/POSIX like shells (bash, ksh93, zsh, yash, mksh at least) have a pipefail option which you can use to be able to report errors in any component of a pipeline:
SHELL=/bin/ksh # or zsh, bash...
0 * * * * set -o pipefail && /var/script.sh 2>&1 | tee -a /var/script.log

Comment: So many thanks for *that* much detail!
Answer: cron wants to tell you about any cron job that produces output. It wants to email the results to you. If you don't want to receive email from cron, ensure your jobs produce no output: don't use tee, just redirect the output
0 * * * * /var/script.sh >> /var/script.log 2>&1

Note also I removed the parentheses: there's no point in running the script in a subshell.
Comment: D'oh!, Thank you @Stéphane as always!


How to find out right away when a new Uniswap Pool is created with liquidity

Question: I want to find out whenever a new Uniswap pool is created and funded with an at least .5 ETH of liquidity. Is there a way to do this programmatically?
Answer: Disclaimer: I work with QuickNode
You can track these events using QuickAlerts and get realtime notification as soon as they occur.
You have to track the topic0 hash of the event + the smart contract address.
Let me explain how:

For Uniswap v2. You'd have to track Topic0 of the PairCreated event which is 0x0d3648bd0f6ba80134a33ba9275ac585d9d315f0ad8355cddefde31afa28d0e9

For Uniswap v3, You'd have to track Topic0 of the PoolCreated event which is 0x783cca1c0412dd0d695e784568c96da2e9c22ff989357a2e8b1d9b2b4e6b7118

Then the Factory smart contract needs to be tracked too,

Factory contract for Uniswap v2: 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f
Factory contract for Uniswap v3: 0x1F98431c8aD98523631AE4a59f267346ea31F984

Learn how to setup QuickAlerts here:

Using the GUI, Docs Guide Video
Using the REST API, Docs Video

The expression to track would be the events would be,
For Uniswap v2,
(tx_value >= 500000000000000000) && (tx_logs_address == '0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f') && (tx_logs_topic0 == '0x0d3648bd0f6ba80134a33ba9275ac585d9d315f0ad8355cddefde31afa28d0e9')

For Uniswap v3,
(tx_value >= 500000000000000000) && (tx_logs_address == '0x1F98431c8aD98523631AE4a59f267346ea31F984') && (tx_logs_topic0 == '0x783cca1c0412dd0d695e784568c96da2e9c22ff989357a2e8b1d9b2b4e6b7118')

For both v2 and v3
(tx_value >= 500000000000000000) && ((tx_logs_address == '0x5c69bee701ef814a2b6a3edd4b1652cb9cc5aa6f' && tx_logs_topic0 == '0x0d3648bd0f6ba80134a33ba9275ac585d9d315f0ad8355cddefde31afa28d0e9') || (tx_logs_address == '0x1F98431c8aD98523631AE4a59f267346ea31F984' && tx_logs_topic0 == '0x783cca1c0412dd0d695e784568c96da2e9c22ff989357a2e8b1d9b2b4e6b7118'))

Deconstructing the expressions:

tx_value checks for the ETH value of transactions 500000000000000000 in the above examples as the value needs to be mentioned in Wei.
tx_log_address checks for the address of smart contract.
tx_logs_topic0 checks for the log topic0 of the emitted logs.
Answer: You can do this with web3.py by listening to PairCreated events emitted by the factory address and there after check whether this project launched with liquidity or not using Uniswap liquidity pool pair address abi to check for added liquidity amount.
from web3 import Web3

web3 = Web3(Web3.HTTPProvider("Enter your Alchemy Node"))
uniswap_factory = '0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f'
Uniswap_factory_abi = json.loads('Enter ABi')
contract = web3.eth.contract(address=uniswap_factory, abi=Uniswap_factory_abi)
liquidityPairAddress = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2" #It's standard for most token to pair with WETH Address so we will be checking these pools.
lp_abi='Enter Uniswap v2 ABI' #Here is Uniswap V2 Address-0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D

def get_token_from_lp(lpAddres):
    uniswap_v2_pair = web3.eth.contract(address=lpAddres,abi=lp_abi)
    tokenA_address = uniswap_v2_pair.functions.token0().call()
    tokenB_address = uniswap_v2_pair.functions.token1().call()
    if tokenA_address == liquidityPairAddress:
       return 0
    elif tokenB_address ==liquidityPairAddress:
       return 1

def get_liquidity_balance(lp_address):
    lp_contract = web3.eth.contract(address=lp_address, abi=lp_abi)
    reserves = lp_contract.functions.getReserves().call()
    index= get_token_from_lp(lp_address)
    balance = reserves[index]
    return balance

event_filter = contract.events.PairCreated.create_filter(fromBlock="latest")
while True:
    try:

        #events = event_filter.get_all_entries()
        events = event_filter.get_new_entries()

        if len(events) > 0:

           for event in events:
               if (event['args']['token1'] == liquidityPairAddress):
                   tokenAddress = event['args']['token0']

                   lp_address=contract.functions.getPair(tokenAddress,liquidityPairAddress).call()

                   lp_balance= get_liquidity_balance(lp_address)

                   tokenLiquidityAmount = float(web3.from_wei(lp_balance, "ether"))
                   print(f"Token Address: {tokenAddress}, Lp Amount{tokenLiquidityAmount}")

I hope this starter code get you going.
Comment: Is there a way to do this for Uniswap v3?
Comment: It's basically the same process just some slight changes in terms of router and factory address


Permute "aaaaabbbbbccccc" so that no two identical letters are adjacent

Question: This is a follow up question to Application of PIE. How many strings with the letters "aaaaabbbbbccccc" are there so that no two identical letters are adjacent?
Answer: My initial thoughts:
There are $15!$ permutations when we consider all letters to be distinct (for starters!), say $a_1,\ldots a_5$, and similarly for $b$'s and $c$'s. The conditions to avoid are $A(i,j)$, $B(i,j)$, $C(i,j)$ (where $i < j$), where e.g. $A(i,j)$ means all permutations where $a_i$ and $a_j$ are adjacent etc. So we need to count all permutations that avoid all the conditions (classical inclusion-exclusion), and then divide the result by $5! 5! 5!$, because in the final result we cannot actually distinguish the $a$'s, $b$'c and $c$'s.
How to count $A(i,j)$: we merge $a_i$ and $a_j$ to one symbol $a(i,j)$ and so we are left with $14!$ symbols, that we permute. In the final result, we can expand $a(i,j)$ back to either $a_i a_j$ or $a_j a_i$ and get two permutations that obey the condition. So we have $2!14!$ many permutations in $A(i,j)$ for every $i < j$. And we have ${5 \choose 2}$ such conditions. The same holds for all $B(i,j)$ and $C(i,j)$ as well.
So we have $15! - 3\cdot {5 \choose 2} 2! 14!$ as the first approximation.
Of course we double-count here: conditions $A(i,j)$ and $A(l,k)$ can both occur at the same time. There is a difference here when $(i,j)$ and $(l,k)$ overlap or not. In the latter case we have $2!2!13!$ many different permutations (two new symbols, both of which can be expanded in two ways), in the former $3! 12!$ ways (one new symbol for 3 different $a_i a_j a_k$, expanded $3!$ ways. Of the former type are ${5 \choose 2}{3 \choose 2}$ pairs, and the latter ${5 \choose 3}$ many.
ALso, conditions $A(i,j)$, $B(i,j)$ can occur at the same time. (and similarly $A$ and $C$ and $B$ and $C$ conditions). Collect of all these together as well, and add to the previous.
And so on. This might be too complicated, but it's the first thing I came up with.
Answer: There is a three-dimensional recurrence for this: let $f(x,y,z)$ be the number of combinations of $x$ a's, $y$ b's and $z$ c's so that no two identical letters are adjacent and the first letter is an "a".
$$f(1,0,0)=1$$
$$f(x,y,z)=f(y,z,x-1)+f(z,x-1,y)\quad\text{if }x>0\text{ and }0\text{ otherwise.}$$
So a simple JavaScript code to compute this is:
<code>function f(x,y,z)
{
    var mem=[];
    function f2(bag)
    {
        if( bag in mem ) return mem[bag];
        if( bag.toString()=="1,0,0" ) return 1;
        if( bag[0]>0 ) return mem[bag]=f2([bag[1],bag[2],bag[0]-1])+f2([bag[2],bag[0]-1,bag[1]]);
        else return 0;
    }
    return f2([x,y,z])+f2([y,z,x])+f2([z,x,y]);
}
var ans=f(5,5,5);
alert(ans); // which gives 7188 but I'm not sure if that's correct.
</code>
Answer: I made an Algorithm and found the same answer as user1537366, then I search for a general formula, and Here it is
Comment: Please explain the main contents of the link and give the formula here. Link only answers are discouraged because they become useless if the link dies.
Comment: Any proof for that formula:
$a(n)=2\sum_{k=0}^{[n/2]}\binom{n-1}{k}\left(\binom{n-1}{k} \binom{2n+1-2k}{n+1} + \binom{n-1}{k+1}\binom{2n-2k}{n+1}\right)$?
Answer: Best approach I think just use recursion, and a few appropriate functions:
$f(5,5,5) = a(4,5,5) + b(5,4,5) + c(5,5,4)$
$a(a,b,c) = b(a,b-1,c) + c(a,b,c-1)$ etc..
$a(-1,b,c) = 0$ etc.
Where $f(a,b,c)$ is the total number of sequences with $a$ a's etc.
$a(a,b,c)$ is the number of sequences where the last letter is 'a', and we can still use $a$ a's, $b$ b's etc.
Other option would be to use inclusion/exclusion, but that would have some very difficult functions for the duplicates.
Comment: Exactly, I was just going to post my answer, which is slightly simpler because of symmetry, but these methods do not give a easy solution for the general case that is in the question linked. Also, you might want to change the function names to capital letters!
Answer: According to Sequences with Adjacent Elements Unequal, the number of sequences of a's, b's and c's comprising $n$ of each letter such that no two identical letters are adjacent is:
$$3\left(\sum_{v=0}^{\lfloor(s-1)/2\rfloor}{s-1\choose 2v}{2v\choose v}{s+v-1\choose v+1}2^{s-1-2v}+\sum_{v=0}^{\lfloor s/2\rfloor}{s\choose 2v}{2v\choose v}{s+v-1\choose v}2^{s-2v}\right)$$
The crucial trick was to note that the blocks of b's and c's between consecutive a's are alternating.


Post closed arbitrarily

Question: There was a post on Kids PC or Mac games that on SuperUser that has been closed because it was "not computer related". Can someone please correct this! Last time I checked PCs and Macs were both types of computer.
Comment: I rolled back the edit because I wasn't looking for an explanation of why it was closed as a reason was already given. The reason was a fallacy.
Comment: What I was really looking for was either for the post to be re-opened, or for the correct reason to be given on the post itself. Otherwise it looks like the person who closed it is being arbitrary and unreasonable.
Answer: With all the games stuff, SU is blocked by firewalls from several companies. I think they try to reduce these questions.
Comment: Fair reason - Then perhaps there should be a closure type of "closed because it was entertainment related". It is a pity that companies have to be idiots like that, as otherwise it was, I though, a reasonable question.
Answer: I closed the post and I followed Jeff Atwood's precedent of using the "Not Computer Related" Option (we have a limited number of options to choose from and this is the best fit).
Questions that are just asking about games are most likely not going to be allowed going further on SuperUser.
Comment: Perhaps a new closed reason is needed. It did look unreasonable given the OP said "PC or Mac" and that SU has been said to be for "anything computer related"
Comment: Colin: I have no problem with there being an extra close reason added (it would make things less confusing definitely). You could make the argument that just because someone said PC or Mac that still makes them much more games related than computing related. Although the games topics looked to be very popular, a lot of users were also complaining it runs the risk of turning SU into a games site instead of site where you get actual computing questions and answers.

Post closed arbitrarily


Mobile app for bitcoins?

Question: Is there a mobile app that I can use to buy/sell bit coins? Would it be useful if I create one?
Answer: There is a lot of applications allowing you to easily trade bitcoin on your mobile phone. Almost every bigger Bitcoin Exchange has one. Take a look at cex.io, bitfinex.com and many more, they do have mobile apps already. There are also decentralized exchanges with mobile applications too. If you check https://coinmarketcap.com/rankings/exchanges/ you will see a quite comprehensive list of exchanges that we have already.
Another thing is that there is no such thing as an app for trading Bitcoin without having proper infrastructure, the trading engine that can handle large volumes and real-time trading, agreements with banks, special permissions, and licenses so my simple answer would be - no.

Mobile app for bitcoins?


How do I transfer funds from the US to Japan if the amount is more than the wire transfer limit?

Question: I'm buying an apartment in Japan (which is where I live), so I need to transfer about $150K from my Bank of America checking account in the US to the apartment building company in Japan. According to the B of A web site, the daily limit on international wire transfers is $1000, so that doesn't sound good. Is there some other way to transfer funds that doesn't have such ridiculously low limits? I don't mind paying fees for the transfer.
Comment: what is the limit regarding transferring the funds to your bank account in Japan?
Comment: Not transferring to my bank in Japan, transferring directly to the bank of the apartment company. They haven't mentioned any limit, so I'm assuming there is none.
Answer: This is a sizable transaction, so it might be worth your time to research this to minimize fees. The difference between a 10% fee and 0.5% fee in this case will be over $10,000.
I've done transfers of that order from Bank of America to Europe. I use an international transfer account (wise.com in my case, no advertising intended) to minimize fees. So the transfer goes

BoA US -> Wise US -> Wise Europe -> Final destination

Total fees on a large transfer were a little less than 0.5%.
This may be different in Japan, but it's possible. See https://wise.com/help/articles/2932156/guide-to-jpy-transfers
As far as I know there is no limit for BoA ACH transfers to different US accounts. It may be useful to upgrade your BoA checkings temporarily to the highest level of service since this is more likely to waive fees and don't have limits.
Answer: Found an answer myself. As long as it can authenticate you through the numbers on a debit card and a text message to a US phone number, BofA's automated on-line wire transfer system will let you transfer up to $2M. The $1000 limit only applies to folks that they can't authenticate in this way.
I didn't ask about fees, but I've done BofA wire transfers in the past, and don't recall anything especially exorbitant.


Looking for YA SciFi book series about boy who finds out he's an alien

Question: Probably published in the 90s. I read it sometime in 2001-2003. The Main Character (male) has these recurring dreams in which mysterious people in lab coats are doing experiments on him. The dreams were actually memories - I think he ends up being an alien? It's a series, and the main focus from what I remember is him trying to figure out who/what he is and where he came from. He spent much of the time on the run I think? Either from government or maybe the lab coat people.
Comment: Hello and Welcome! It looks like you've got a few good details there. Unfortunately they look like they may show up quite frequently in various works, so take a look at [this guide](https://scifi.meta.stackexchange.com/a/9337/68872) and see if you can [edit] in any more details :)
Comment: I'm looking for the same book I believe. The Atrian Messenger. He meets an older alien who protects n trains him.
Comment: I have been unable to find *The Atrian Messenger*, so I'm skeptical.
Comment: Ironically it could just as easily be The Maze Runner, although that was published much to late and doesn't involve aliens
Answer:
The Antrian Messenger by G. Clifton Wisler. It is indeed part of a trilogy.
From a Goodreads review:

Scott's always been a pretty ordinary kid--so he thinks--but when
  certain odd occurrences keep happening to him, he is left with tons of
  questions. Why is he having premonitions, and what will he sacrifice
  if he dedicates himself to stopping the disasters he's dreaming?
  Before long he uncovers the truth of his origin: he is not human, but
  Antrian, and an older and wiser companion named Tiaf is ready and
  waiting to teach him about his heritage (and his prophetic abilities,
  among other things). But he soon realizes he can't both fulfill his
  destiny and live a normal life with his family, so he has to make the
  hardest choice of his life--and once he chooses, he can't go back.
Comment: Just noting that, if ever accepted, this would probably be a dupe of https://scifi.stackexchange.com/questions/9152/looking-for-two-stories-about-a-telekinetic-boy/16600#16600


Reading from dynamically created tables with LINQ

Question: We create tables in runtime. They have the same schema layout as tables that exist in our DBML but with an alternate name. We want to set the table names in runtime in our use of Linq to Sql.
Using wrapper classes on the Metadata as outlined in https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=4233721&SiteID=1 works great for the updates, deletes and inserts.
Does anyone know how we can get the read of the alternate table to work?
Answer: You need to use an external mapping file.  Populate the xml with the names of your table at runtime.  This over-rides the attribute based mapping.
Answer: You need to new up your LINQ expression at run-time via System.Linq.Expressions


meaning of " If that's what it takes "

Question: While watching captain America in English, I heard Chris Evans saying " If that's what it takes " What exactly does the sentence mean ?
Comment: Have you tried googling it? **What it takes** is an idiomatic expression: https://idioms.thefreedictionary.com/what+it+takes
Comment: @MichaelRybkin - I don't think that particular meaning of *what it takes* is quite correct here, though.  "She's got what it takes" means "She has the necessary qualities", but "If that's what it takes" means something more like "If that is the action that is required."
Comment: @stangdon I totally agree. I thought that it'd be very easy to connect the expression I mentioned in my comment to the one used in the movie because it's essentially the same expression, just used a little bit differently and in a different context.
Comment: **It takes brains** to be a rocket scientist. John has **what it takes** to be one. That's an example.
Comment: @MichaelRybkin - You know, the more I think about it, the more I think the two senses are very closely connected, though.  They both mean "what is necessary".
Answer: I haven't seen the movie so I don't know the context. But in general, "that's what it takes" means that these are the things required to complete this job or reach this goal.
A very literal example would be, "What does it take to replace spark plugs in my car?" To which someone might reply, "You need a set of socket wrenches, a spark plug puller, and of course the new spark plugs."
The phrase is often used for less concrete requirements. Like, "John really has what it takes to be a champion athlete", meaning, he has physical strength, a willingness to practice long and hard, etc.
Answer: This is a straight use of the verb "take", though it is one of those verbs with dozens of meanings, so you have to go through quite a bit to find!
Looking at Merriam Webster for example, they have:

take (verb)
...

to adopt, choose, or avail oneself of for use: such as

...
e. (3) : need, require
// takes a size nine shoe
// it takes two to start a fight

In the film, the dialog goes:

Peggy Carter: What do you plan to do? Walk to Austria?
Steve Rogers: If that's what it takes.

when he says "If that's what it takes" in response to her question, he means (in this context):

If that is what is required [in order to get to Austria]

meaning of " If that's what it takes "


How to discern between the accelerator and atmospheric neutrinos in detectors?

Question: If an experiment is detecting accelerator neutrinos, then how can one distinguish the accelerator $\nu_{\mu}$-neutrinos from the atmospheric $\nu_{\mu}$-neutrinos? As I know, both of these types of neutrinos will be having almost the same energy ranges. Then how is it to possible to discriminate these two types of neutrinos in a given experimental setup?
Comment: This is a matter that the experimenters generally address during design. The details vary hugely, but there are a handful of pretty standard techniques. Experimental proposals and initial design documents are almost always publicly available by the time they're building it (look on arXiv), so you can get the details straight from the horses mouth.
Comment: That will depend on the experiment. Are you specifically thinking about the DUNE experiment?
Comment: @JohnRennie You can consider the example of NOvA. How is it known that the neutrinos detected in this experiment are accelerator neutrinos generated by NUMI beam only and they are not the atmospheric neutrinos?
Answer: The design of the NOvA detectors is described in this article on the IOP web site.
The proton beam that generates the neutrinos is pulsed so the detectors know when to expect neutrinos from the source. In addition the detector can measure the direction of travel and the energy of the neutrinos. Combining these allows neutrinos from the source to be distinguished from atmospheric neutrinos and signals from other background sources.


Dielectric permittivity tensor of rank 2

Question: In special relativity, one knows the Euclidean and Minkowski metric to raise or lower the index of a covector or vector. The Euclidean metric is a (1,1) tensor and is represented by a 3x3 identity matrix while the Minkowski metric in matrix form is a 4x4 diagonal matrix with all of its diagonal element unity except for the last one which is -1. But in the case of other field of physics which involves tensors like dielectric permitivity tensor (consider a rank 2 dielectric tensor) in nonlinear optics, what metric do I use to raise/lower the indexes?
Answer: You use the metric of your coordinate system; if that's Cartesian, then it's a Kronecker delta. Since permitivity is measured in Farads per meter- emphasis "per meter"-- it should transform accordingly.
Comment: If the metric is the Kronecker delta, then to change from E field vector into E field covector, I simply transpose it without complex conjugation? In other words the E field in vector and covector form are basically identical?
Moreover, would you please describe what a contravariant tensor is? I only know contravariant coordinate.
Comment: By the way, I think electric permittivity tensor does not act on a position vector, it acts on electric field vector.
Comment: I think I meant covariant. To get a 1st understanding of the 2 types of transformations (of a vector)--consider a simple coordinate transform x --> 2x, that is double the length of the basis vector. Positions are cut in 1/2--which is "contra" to the variance of the basis vector--hence contravariance. Meanwhile, a gradient, such as Volts per meter would double--since the "volts" in space don't change, but the length of "delta x" doubles. So gradients vary with the change in basis: "covariance".
Comment: Yes: it acts on the electric field (V/m) to give the displacement field (C/m**2)--hence its units are F/m.
Comment: Then which metric do I use to change from E field vector to E field covector? If it's the kronecker delta like you said, then the covector is the same as the vector. I asked this because I am used to conjugate transpose which one uses in an inner product. I have got the impression that a tensor of rank (1,1) is similar to a inner product.


How to achieve invariable background during scene change in cocos2d?

Question: Scene A and scene B have same background. If transition from A to B has animations (say, move in from left), the background will also take part in it. I do not want this. In other words, the background layer belongs neither to scene A or scene B, but something parallel to scenes and laid behind. Can I achieve this?
Answer: Although I don't think you can do this with scenes directly,
A plausible work around would be to do the following:

Do a scene replace with no transition
Set all sprite's positions to offscreen, then CCMove them into their proper places.

It's messy, but it could work.
Adam


Does Mail log errors into a console or text file?

Question: Does Mail log errors into a console or text file somewhere?
Answer: Start with:
<code>/var/log/mail.log
</code>
most easily viewed with /Applications/Utilities/Console.app
Comment: Looked there already, didn't exist.
Answer: Go to /Library/Scripts/Mail Scripts/Turn On Logging.scpt and Run that.
Otherwise, go here: http://hints.macworld.com/article.php?story=2004101603285984
Answer: Apple have provided an API to a logger database. Apple use the datbase in Mail
The messages are then viewable using the Console.app
Choose All Messages in the lefthand sidebar
Filter on Mail
e.g.


How can I run exe files in Dolphin on Kubuntu

Question: I have wine installed. But how can I set it default for running exe files?
Comment: If wine is installed correctly, double click an executive file will open that file using wine by default. Please edit your question and provide more details, such as the version of Ubuntu, how did you install wine, what happens when you double click on an executive file?
Comment: @user68186 - In Kubuntu 18.04 I had the same problem with the stable wine version installed, had to create a desktop file as indicated in my answer  below.
Comment: @CentaurusA - I have simply edited the title to make things clear.
Comment: Should your title say "How can I use Wine..." rather than "mime"?
Answer: When you right-click on the .exe file, you go to "Open with application with", then you select WINE.
Comment: In case `exe` files are not run as expected on (double) click (case implied by the OP, otherwise the question makes no sense), it might also be that no "Wine" program appears when trying to select it from "Open with".
Comment: For some reason, WINE is not an option. I have version 6.0, as this is the latest version I can get from the repos.
Answer: Normally simply executing the exe file with (double) click in the file manager should run it through Wine. If for some reason that doesn't happen (beside trying to re-install Wine in order to get the expected behavior) you could do the following:
In terminal run wine path_to_file.exe.

In order to run it with (double) click: create a ~/.local/share/application/wine.desktop file with the lines like
[Desktop Entry]
Exec=wine %f
Name=Run in Wine
Mimetype=application/x-dosexec
Categories=System;Settings;

then make Run in Wine the default "application" for exe files (in Dolphin: Properties > (tab) General > Add).

Alternatively, create a ~.local/share/kservices5/ServiceMenus/run_wine.desktop like
[Desktop Entry]
Actions=wine
Mimetype=application/x-dosexec
ServiceTypes=KonqPopupMenu/Plugin
Type=Service
X-KDE-Priority=TopLevel

[Desktop Action wine]
Exec=wine %f
Name=Run in Wine
Icon=wine

in order to have a right-click context menu option ("Service Menu") in Dolphin.

I cannot test now, as I don't use Wine as we speak, but konsole -e wine %f or sh -c 'wine %f' might be needed for the Exec line.
If someone can confirm Exec=wine %f works, please comment.
Comment: There are some typos here. `~.local` should be `~/.local`, and `application` should be `applications`.


Is in-person double-spending attacks negligible on bitcoin payments?

Question: If I'm planning to accept in-person payments in a store, is it negligible a double-spending attack or isn't it too hard to do?
Answer: Double spending attacks can certainly happen in person. A customer could have set up a system on a different computer which they remote into on their phone to initiate a double spend attack. However double spends can really only exist under certain conditions, so if you are planning on accepting unconfirmed payments, you should check that those conditions do not exist. This gives you a higher confidence in that transaction confirming.
You should make sure that the transaction does not have:

A low transaction fee
BIP 125's Opt in RBF flag set
A locktime that is in the future
Spending from any unconfirmed transactions
Is unusually large (e.g. several kilobytes)

If you check for these things and they are not in a transaction, you can be reasonably confident that the transaction will confirm.
You can also have a system set up to immediately perform a Child-Pays-For-Parent transaction so that you can ensure that the transaction has enough transaction fee to be confirmed. Note that if the transaction is Opts into RBF, this method may not work.
Comment: Thank you for the awesome answer! Just to clearify, is there any way in which I can calculate the minimun fee amount (so I can check if the payed fee is really too low)?
Comment: There is no minimum fee amount. You can use sites like http://bitcoinfees.21.co/ and https://bitcoinfees.github.io/ or Bitcoin Core's fee estimator to see what a fee rate for something to confirm within some acceptable window of blocks for you (e.g. 20 blocks) and see if the fee rate paid in a transaction is more than what the estimator suggests for your window.
Comment: Thank you Andrew, that's exactly what I was looking for!
Answer: Double spend attacks are possible in person just as they are online.  These attacks aren't actually spending the same coins twice on the blockchain, but rather tricking a retailer into thinking a transaction is valid for long enough to get away with the good.
However, setting up such an attack in non-trivial.  It becomes even more difficult if the retailer is checking for the items listed in @Andrew's answer.  As such, purchases under a certain amount simply aren't worth a crook's time in setting up a double spend attack, and probably aren't worth a retailer's time protecting against one.
Consider how things work with retailers who accept card payments.  Starbucks is known for not requiring signatures for credit card payments that are under a certain amount.  If you don't know, signing a receipt on a credit card payment is a legal way of transferring the liability of fraud.  If a signature is obtained (even if forged), the liability is on the issuer of the card.  If a signature is not obtained, the liability is on the retailer.  Starbucks has decided that it is in their best interest to accept the liability of fraud because requiring a signature from each customer would slow down their lines and they would make less profit.  The cost of the inevitable fraud (to which they are liable for not requiring a signature) is lower than the potential profits they make from increased customer throughput.  Fraud isn't eliminated, but mitigated.
Accepting bitcoin is no different.  Depending on the price of the goods you are selling and the cost to your business of preventing double spends, each retailer needs to mitigate this fraud accordingly.


Board like strategy map

Question: I want to make a strategy game like Risk. I want to use C# for the mechanics and Unity for the graphics.
My problem is that I don't know how to create the map itself and integrate it with C#. I don't want a tile map but instead I want to create a customized world map, with different provinces defined by me.
The map would be something like Imperial Glory, where you see it top down and then move your generals like chess pieces. I'm not implementing any real time battles at this point, it's just something really simple, like a board game. Could anyone please help me?
I'll try to explain it a bit better: I need to create a map of the Mediterranean basin that would cover all the land occupied by the Romans at the height of their empire.
Next, I'll divide the map into 20 provinces (Italy, Gaul, Germania, etc), each one producing a set ammount of resources and population. I also want them to have their own wheather and buildings (for example, you can only train soldiers in provinces that have a barracks). I guess I'll need a text box popup that appears when you click on a province to display it's information.
I'll also need some buttons to open dropdown menus or perhaps whole windows, for other purposes such as diplomacy, statistics, tech trees, etc.
I wanted the map to be in 3d because I think it would be much more interesting to look at it in perspective instead of flatten 2d.
I'm fairly new into Unity so I really admit that I have no idea where to start. Please, have patience with my ignorance. Thank you very much for all your help. If there are any doubts about my question, please let me know and I'll try to explain it better.
PS: I think I'll make it a turn based game since I think this would make it simpler to code and faster to run.
Comment: Could you be more specific about what you mean by "*customized world map*"? On a [*Risk*](https://en.wikipedia.org/wiki/Risk_(game)) map, although territories look visually interesting, in terms of gameplay they are just a [graph structure](https://en.wikipedia.org/wiki/Graph_(abstract_data_type)).
Comment: By customized I mean with imperfect boundaries between the provinces, since I'm trying to avoid tiles because of the artificial look of the squares.
Comment: Still more details please. Are you looking just for how to create the graphics or how to handle them as part of game logic? Do you want them to be procedurally generated? Raster- or vector-based? Do you need to be able to zoom the map? (You can edit the question to clarify.)
Answer: Unity is a game development platform that uses languages, such as C# and JavaScript, to create scripts that provide behaviours for elements within your game. If you're creating a 2D top-down game, you could use tools such as GIMP, Paint.NET or Photoshop to create graphics that you would import into Unity as assets.
For your map, you could create a world comprised of continents and provinces. Reddit's Worldbuilding subreddit (filtered to Maps) has some great examples, tips and tricks on creating worlds.
Example Map:

I moved these apart in Photoshop, making it easier to create a texture atlas, disabled the background, saved it as a .png file, and imported it into Unity as a Sprite with Sprite Mode set to Multiple. Finally, I created an empty GameObject called World, containing each of the continents, and a cube object behind them which fills the camera's view, acting as a surrogate ocean.
2D / 3D view of the result:

As you can see in the 3D perspective, the map is separated by four continents. My experience with Unity is limited, but this could be a good place to start, or give you an idea of what to do. I also suggest checking out Unity's official tutorials, their online forum and their answers site, if you want to learn more about the platform and how to use it.
Comment: Could you please explain a bit more about how I would import the map as an asset? I'm not lazy about searching for what I need, (believe me, I've literaly spent the whole day trying to find an answer) but you seem to have already grasped the notion of what I'm looking for.
Comment: Do I create a flat rectangule to serve as the "board" and then add the map as a texture? If so, how would I break it down into individual provinces? I need the provinces to change color according to the owner and I'll also need to store a bunch of variables for each one, such as resource production, wheather, buildings constructed and whether it's possible to build them or not (such as ports in inland provinces), etc.How would I get around to do that? Thank you for replying
Comment: I edited my post to provide an example.
Comment: That actually looks pretty good. I try to get around and do the GameObjects and later I'll tell you guys how it went. Thank you.
Answer: Just as it has been said in the comments, it is not clear if you are asking both how to design/create the assets that will represent the provinces, or just how to connect the assets representing provinces within your C# code. My guess is that you are looking for the later.
So, first of all, you don't need to have one rectangle for the map and then subdivide it into the countries and then provinces. You could have a separate GameObject asset for each province. Then, a simple approach would be to give a proper name for each asset of each province, then to create in C# a custom class with a Dictionary that holds data for each province (the same can be achieved with a List if you prefer it over Dictionaries).
Then, each entry in such Dictionary would be a province with the Key being province name, and when you reference any given one (e.g. using the name of the province object that was hit by a mouse click), you could access its other info stored at that Dictionary entry. For example, for each enter in the Dictionary you could have a field for the number of units garrisoned there, another for the resources, another for weather, another with the color name of the owner, or even a sub-list within the Dictionary, containing the names of the neighbor-provinces of that province.
Comment: Actually I need to know both: how to create the provinces and also how to connect them to the C# code for the game mechanics. Thank you for your reply, I'll check it out and come back later to tell how it went.
Comment: If I were you, I would first try what I said: create one GameObject for each province in the map. It means, one 3D model for each or one 2D sprite for each. You can easily do that respectively in a free 3D modelling toll such as Maya, or even in Paint. If you have one GameObject for each province, it will be easy to use the codes I've linked to detect mouse click over each and then retrieve the info related to each from the Dictionary object.
Answer: I was working on a very similar (but more complicated) project. The basic idea is to create a colormap and a 2D sprite and perform a per-province palette-swap in the sprite's fragment shader based on the province's RGB value.
Conceptually, you'd keep two textures, a colormap texture, and a lookup texture. The colormap could be whatever size you want, but the lookup texture has to be of size 4096*4096. The details are contained in the accepted answer to my earlier question on the topic.
This is a very graphically cheap way to do this, though it can be pretty computationally expensive to repeatedly update a large texture.
This also allows you the option of easily projecting your texture over a 3D terrain if you ever want to go that route (for example, if you ever want a map like the one in Risk 2, Europa Universalis, or Crusader Kings 2).
Another way to do it is to read through a colormap like the one in my linked question, and create 1 2D sprite per province. This approach was taken by the (now-defunct) Of Bears and Eagles project (which is coded in Java), but it is worth noting that a heavily-mutated private fork of the project is being run by Reddit user Kalelovil, and is pseudo-regularly updated here (the project on Reddit hasn't been very active, most of us who contribute do so over the project's Slack group). The project was recoded in C# once Kalelovil took over (in order to work with Unity), so if you want further details on how to write the map parser, I'd suggest seeking out Kalelovil on Reddit (he is active on Slack, so I imagine he is also active on Reddit, but I haven't checked).
I'd share my own code, but I use several classes and several files to generate my (now-obsolete) 2D maps, and honestly it would be extremely cumbersome to paste and format all that code (several hundred lines). This is pretty memory intensive, and it can be graphically intensive depending on the number of provinces you want to display, but it would be perfect for a game with only 20 or so provinces. You can use shaders to decrease granularity.
A third option would be to fork this Github project and use it to generate a 2D mesh for each province from a vector graphics file from path's. The linked file only handles the MoveTo and LineTo commands, but it can be easily modified to support Horizontal and Vertical commands. Other, more complex commands (Bezier curves and arcs) are going to be harder to implement, but are still within the realm of possibility.
Finally, as a last resort, if you don't mind paying large sums of money, the Unity Asset developer, Kronnect, has an entire string of (admittedly expensive, but extremely well-maintained and well-supported) assets that would definitely cover any and all map needs you might have. I personally own a copy of their World Political Map 2D Edition and their World Map Strategy Kit, and they both run like a charm. All the bottlenecks I have encountered (aside from the occasional bug which is usually fixed in a Beta within hours to a day of my report) have been in my code.

Board like strategy map


html form vertical textfield

Question: can some one help me creating a vertical text field. actually I want to create a email subscription form in which I want to place a text field which can only take one character per row.
Comment: Should the letters also be rotated 90°? Or should it be like `abc` with not rotated letters?
Comment: don't need to rotate letters, should be like a newline than b and so on
Comment: This sounds like a weird requirement. Can you explain, why you want to do this, because there may be better ways to do it, like multiple text inputs with `maxlength=1`.
Answer: You could use something like <textarea style="height: 5em; width: 0.8em;" ></textarea> (this will display the characters vertically). You may have to play with the height and width.
Comment: it's really help full and works fine initially but when the text grows from it's existing height it's showing up a scrollbar. to hide the scrollbar I have added overflow hidden but in this case it's hiding the overflow text. Is there a possibility to scroll the text upward when it reaches the end of the field
Comment: How about ``
Answer: The writing-mode and filter properties of css can be used make a vertical effect to a textarea. Following is an example html page, using these properties is a class

  <textarea class="verticaltext"/></textarea>

While reading values form the textarea you may have to split it and get each character.
You may apply this css to div elements also.
Comment: Please try it in Internet Explorer

html form vertical textfield


Remove embedded subtitles from an .mkv file?

Question: Is there a way I can remove subtitle data from an .mkv?
Answer: Use MkvToolNix.  The mkvmerge tool can do exactly what you want. It's a very capable Matroska manipulator and should be able to remove any kind of stream from an MKV without recoding all the other streams.

On Windows, download the latest version from here. Just run the installer.
On Linux, you can find the package mkvtoolnix in your repository, or alternatively download them from the homepage.
On OS X, the easiest way would be to install mkvtoolnix through Homebrew.

I think one of these commands will do what you want:
# assume input.mkv has 3 subtitle tracks
# remove subtitle track 2 (copy 1&3) from input.mkv & save to output.mkv
mkvmerge -o output.mkv --subtitle-tracks 1,3 input.mkv

# remove all subtitles (copy none)
mkvmerge -o output.mkv --no-subtitles input.mkv

Comment: Usage note: The track numbers supplied to `--stracks` are not 1 (first subtitle), 2 (second), 3 (third), etc. Use `mkvinfo input.mkv` to enumerate the tracks in the .mkv first (e.g. track 0 may be video; 1,2,3 may be audio; 4,5,6 may be subtitles) then use the 0-based track number with the `--stracks` switch. In quack's  example above this might be `--stracks 4,6`
Comment: I have found the output files from MkvToolNix (mkvmerge) to be unusable by some players & converter (ArcSoft VideoConverter in particular - I was trying to strip the subtitles prior to converting them for viewing on my iPhone).
Comment: To confirm, does the GUI version of the program also remove subtitles without re-encoding?
Comment: @HashimAziz yes, mkvtoolnix is incapable of re-encoding. all operations on the stream level are copying.


Reducing belly fat through home work outs like plank

Question: I Workout at home, doing push ups mostly. I even do a bit of jump rope, 1000 jumps per day. My biceps, triceps and chest have a good shape and are toned. But my belly has fat. How do I reduce my belly fat through home work out?  Does exercises like plank help me in reducing the belly fat? I know spot reduction is not possible. But will plank help me reduce those few extra kilos.
Comment: This question has been asked a hundred different ways on this site. The only thing that reduces fat is a negative energy balance (a caloric deficit). Exercise can contribute to this, but what you put in your mouth makes the biggest impact.
Answer: Planks will not help reduce body fat.
As JustSnilloc wrote ....  creating a caloric deficit is the only way to get rid of body fat.
Nutrition comes first for fat loss.
Second is exercise.  What are you currently doing for exercise is not bad.  But is it ideal?  No.
At some point you should consider adding some heavier resistance training.  Check craigslist or facebook marketplace for a used set of power blocks or the box flex version of the same...  basically dumbbells and start doing resistance training.
Squat
Deadlift
Dumbbell Rows
Dumbbell Overhead Press
Dumbbell Floor Press
Lunge
etc
5-7 exercise with the power blocks or similar dumbbells.
3 sets of 8-12 reps
3 times per week
Add the jump rope and you will be off to a great start.
But you still have to be at a caloric deficit.


Any way to make it so that i can kill anybody in Fallout 4

Question: By this I mean killing the npcs that have immunity and get right back up.
If there is any way to modify the file or mods .
Comment: @Nolonar I'm reading this as being something like [this guy](http://gaming.stackexchange.com/questions/121863/how-do-i-kill-the-jarl). It's asking how to remove the essential flag from NPCs. Which so far as far as I can tell isn't possible in-game, but I haven't been able to test `setessential` for myself
Comment: I'm not sure I understand what the point of this question is. I mean, you can do anything through modding or modifying the game's files. People have turned GTA 4 into Watch_Dogs by modding the game, and if you replace all the game's files with those of another app, you could even turn Solitaire into Windows 10. If you're asking which mod lets you kill essential NPCs, that would be a software-rec and off-topic.
Comment: This is my reading as well.
Answer: Almost certainly not [yet].
Keep in mind, even if you can change the "essential" attribute to make plot-essential characters killable, Bethesda's Fallout games are coded to prevent hostile or potentially hostility-provocing actions against children.  In Fallout 3, it took a user a user-created game mod to restore the ability to kill children, and both Fallout: New Vegas and Fallout 4 have that same hard-coded idiosyncratic stupi...  ... "behavior."
(And, ugh, what a dumb design decision the whole no kid killing thing is.  One of my fondest memories in Fallout 2 was when the shock of noticing my Childkiller reputation - I accidentally clipped a couple kids with the blast radius of a rocket I fired early on in the game, for which I was punished by bounty hunter attacks and worse prices when trading.  Brilliant!  Certainly much better than the idea of jamming a bunch of invulnerable NPCs into the game that do nothing but get in the way and annoy me.)
Comment: @DCShannon  And...? I already have about 50,000 StackExchange brand valueless internet points. What am I going to do with 10 more?  Or 10 million more, for that matter? The path to web Zen begins with realizing that these valueless internet points ("rep" on StackExchange)  are valueless and just about worthless.  (At least for the person _with_ the valueless internet points, that is.)
Comment: @DCShannon That last one. I'm long past that point of caring about privs or being able to contribute better.  Been there, done that (at the highest possible level, I'm an ex-moderator), and figured out that getting more privileges just amounts to additional unpaid effort on my part that serves to make money for someone else.
Comment: Not to mention there's nothing more satisfying than shoving a mini nuke down Mayor MacCready's obnoxious throat
Comment: The rant's a bit off-topic. I could see plenty of people not upvoting due to that.
Comment: @HopelessN00b I assume you want to make a question that others value and find useful. Forgive me if that's not the case. You have a fairly low rep count on this particular SE, so I also assume you're interested in getting more privileges so you can better contribute. Perhaps not.


is there any possible way to know if someone try to login as you?

Question: How would you know if someone use you as "login as" and try to alter data? I know that whenever you changed something in salesforce (e.g. Opportunity record) it will always records the login user as created or last modified id. So there will be no way to edit a record as someone else while you are login, unless you login as someone else.
Answer: Just to clarify your question are you asking if there is a way of checking if an administrator has used the 'login as' feature to sign into a user account and then modified a record?
If they have the 'last updated by' on the actual record that is updated will show the account that has been logged into by the admin. However you will be able to see the IP address of the login by user and the Setup Audit Trail will show admins logging in as other users.
Adminstration Setup>Security Controls>View Setup Audit Trail
Comment: Yes! Another question could only be the admin who can do that? Can s/he grant privilege to someone to use the "login as"? I know this out of the range of my question, but I also wanted to know if that is also possible.
Comment: The 'login as' feature is only available to admins and Salesforce support - it isn't available to grant to any other users.


I am glitching in a bed in Minecraft multiplayer 1.7.2

Question: I am in Minecraft right now, glitching in a bed because I was on top of someone. I tried /kill and /leave, and none of them work. I am in full screen, so I can't exit or go to the menu. Please, I would love to hear your suggestions.
Comment: alt+tab to another window, ctrl+alt+delete and kill the minecraft process
Answer: Press Alt Tab to switch programs and get to the desktop, or Alt F4 to close Minecraft.
Or press Ctrl Alt Delete, get to the Task Manager and kill the Minecraft process.
If that doesn't work, press and hold the power button on your PC.


How does Brahma look?

Question: Does Brahma look like an old deity, having white hair? What is his body complexion - red, golden or something else. Does he use rosaries for chanting? If so then which rosaries does he use(rudraksha or tulasi mala)? Which type of tilak does he put on his forehead - urdhava pundra (u shaped tilak of Vishnu) or tripundra (three lined tilak of Shiva)?
Comment: Does this answer your question? [Why is Brahma depicted as old in pictures?](https://hinduism.stackexchange.com/questions/11259/why-is-brahma-depicted-as-old-in-pictures)
Comment: @TheLittleNaruto this answer describes about why he was depicted as an old deity, but doesn't clears my other doubts.
Answer: To know how a deity looks like we need to look into that deity's Dhyana Shloka (also called Dhyana Mantra sometimes).
For Lord BrahmA, since his worship is prohibited, it's difficult to find a Dhyana Mantra. But I know about a DhyAna Shloka, that is quoted in the book Anhika Kritya (by Shyamacharana Kaviratna Varidhi); first BhAga; first Khanda; section-DhyAnamAlA.
And, it is as follows:

BrahmA kamandalu-dharashchaturvaktrash-chaturbhujah |
KadAchidrakta-kamale hamsArudhah kadAchana || Varnena
rakta-gaurAngah prAmshustunganga unnatah | Kamandalur-vAmakare
sruvo haste tu dakshine || DakshinAdhastathA mAlA vAmAdhascha
tathA sruchA | AjyasthAli vAmapArshwe vedAh sarvehagratah stithAh
|| SAvitri vAma-pArshwasthA dakshinasthA saraswati | Sarvve
cha rishayo hyagre kuryadevishcha chintanam ||
Lord BrahmA holds the Kamandalu (a water pot); he is having four faces
and four arms;  Sometimes (he is seen) seated on a red lotus and
sometimes on the Swan. His body is having an extremely stout structure
and is having a reddish-white complexion. The upper left hand is
holding the Kamandalu and the lower right hand holds the rosary beads;
the lower left hand holds the Sruk (the laddle used while pouring the
Havi in fire); the upper right hand is holding the Sruva (the utensil
in which the Havi is stored);
On his left hand side is present the AjyasthAli (the plate that
contains clarified butter or Ghee); in his front (are present) the
Vedas; on his left is present SAvitri and on his right Saraswati and
in his front are present all the Rishis. One has to meditate upon Lord
Brahma in this way.

So, it does not specify if Lord BrahmA is having white hair and white beard or not. Also, although it specifies that he carries a JapamAlA, but it does not specify what kind of beads (like RudrAksha, Tulasi or any other) that MAlA is made of. And, regarding the Tilaka on forehead, it has no information.
I have also consulted the Deva Kritha Brahma Stotram found here but it is not of any help regarding finding out details of Lord Brahma's physical appearance.
Similarly, I have also checked the Brahma Stuthi Panchakam. But it too does not provide any additional information.
Comment: Well they are different. They have different Dhyana Slokas, different mantras, worship procedures. When Dhyanam is different then we are talking about separate deities. @Archit
Comment: @Archit ok .. no problem.
Comment: Nice answer, upvote. Doubt - are not Savitri and Saraswati the same Goddess different forms - somewhat like Durga and Kaushiki or Kali
Comment: Thanks @Archit Yes, sometimes they are different names of the same deity but sometimes they also differentiate between the two like it is done here.
Comment: Any particular reason? Similar in this case श्रीश्च ते लक्ष्मीश्च पत्न्यावहोरात्रे पार्श्वे। Shri and Lakshmi are your wives..... also aren't Saraswati and Gayatri the same. When we see her as the all mother (just like Durgaji in some cases) and mother of Vedas she's Gayatri, correct?
Comment: Sarswati and Gayatri are definitely different deities.@Archit
Comment: Different? Isn't Saraswati also Vedamata like Gayatri? Wasn't Saraswati the one who helped Brahma with the Vedas and creation?
Comment: Okay thanks, will have to do more research
Answer: Sri Shiva Maha Purana 2.1:1:7:1-6.:

Brahmā said:—
When lord Nārāyaṇa continued to sleep, an excellent lotus of huge size came out of his navel as desired by Śiva.
It was many Yojanas wide and high. It had an endless stalk. The pericarp was of a brilliant hue.
It was very beautiful with the brilliance of ten million suns. It was wonderful, excellent and worthy of vision containing Tattvas.
Exerting himself as before, Śiva, the great lord, with Pārvatī as his better half created me from His right limb.
O sage, having deluded me with His illusion immediately, Śiva in the course of His sport, produced me through the umbilical lotus of Viṣṇu.
Thus, it was that I came to be known as Lotus-born and conceived in a golden womb. I had four faces, red complexion and Tripuṇḍra-marked forehead.

I hope this clarifies all your queries. Prd..

How does Brahma look?


Is redox potential a valid term?

Question: I mean doesn't every compound has its own different reduction and oxidation potential ? Or its just one potential that can be compared to understand which one will get reduced and which one will get oxidised ?
Answer:
I mean doesn't every compound has its own different reduction and oxidation potential ? Or its just one potential that can be compared to understand which one will get reduced and which one will get oxidised ?

A compound has neither. You need to specify the half reaction. For example, take an aqueous solution of $\ce{Fe^2+}$ and hydrogen peroxide, among others. What are possible half reactions for $\ce{Fe^2+}$?
$$\ce{Fe^2+ -> Fe^3+ + e-}\tag{1}$$
$$\ce{Fe -> Fe^2+ + 2e-}\tag{2}$$
and maybe some more exotic ones. For hydrogen peroxide, you would have e.g.
$$\ce{H2O2 -> O2 + 2e- + 2H+}\tag{3}$$
$$\ce{2H2O -> H2O2 + 2e- + 2H+}\tag{4}$$
Notice that these are all written in the direction of reduction, and are associated with a reduction potential. To see which reactions are feasible, you would compare reduction potentials and come up with a redox reaction combining a half reaction as written with a half reaction (the oxidation half reaction) in the reverse direction. For example, hydrogen peroxide could undergo disproportionation:
$$\ce{2H2O2 -> O2 + 2H2O}$$
This is a slow reaction, but the enzyme catalase (which happens to have an iron(III) bound to its active site) increases the rate substantially, as you can see from the oxygen evolving when you put some hydrogen peroxide on a freshly cut slice of potato.

Is redox potential a valid term?

Yes, under certain circumstances it makes sense to talk of redox potential as a property of an aqueous solution, similar to discussing its pH. For example, if a biological cell contains glutathione at fairly high concentration in the reduced and oxidized form (abbreviated as GSH and GSSG), this will determine the redox state of other substances in the cell. If a strong oxidation agent is introduced, it will react with GSH. If a strong reduction agent is introduced, it will react with GSSG. Like mainining a pH with a buffer, the redox potential of the cell is maintained through the ratio of GSH and GSSG (and we could call it a redox buffer).
The analogy between pH buffer and redox buffer only goes so far. The biggest difference is in the role of water. While water acts as an acid and base at any pH (i.e. whenever acids and bases are added), it does not undergo reduction and oxidation for many redox reactions in aqueous solution. Any pair of acid and base will react (because water provides the "reservoir" of hydrogen and hydroxide ions). Many pairs of possible oxidizing and reducing agents will not react, even when thermodynamically favored because there is no good mechanism for the electrons to be transferred (a question of kinetics).
Answer: There is the table of standard electrode potentials. These are values which is relative to the standard hydrogen electrode. They were measured at certain, constant for all, conditions.
To measure actual potentials one can use Nernst equation
$$E_\mathrm{Red} = E_\mathrm{Red}^\circ + \frac{RT}{nF}\ln\frac{a_\mathrm{Red}}{a_\mathrm{Ox}}.$$
Sometimes you just have to compare standard electrode potentials to understand which one is stronger oxidant or reductant.
Comment: Please avoid embedding illustrations from the third party services (use SE uploader instead to prevent link rot), and don't use images for the textual information. There is Markdown and MathJax support to assist you with scientific typesetting, leaving your post searchable and looking uniformly decent across all devices. For more information, visit [this page](http://chemistry.stackexchange.com/help/notation), [this page](http://meta.chemistry.stackexchange.com/q/443/) and [this one](http://meta.chemistry.stackexchange.com/q/86/).
Answer:
Is redox potential a valid term?

Yes it is a valid thermodynamic term. Also oxidation potential is a valid term. These terms differ only by a sign. If a reduction potential of a given half cell is -0.73 V with respect to hydrogen cell. its oxidation potential is +0.73 V. So you have to stick to one term for comparative purposes.
After a century of arguments, electrochemical societies decided to write all the half cells as reduction e.g., $\ce{Fe^{3+} + e- -> Fe^{2+}}$ and call the potential of this reaction as the reduction potential with respect to hydrogen half cell which is arbitrarily taken as zero.
Comment: This does not address the question which seems to be *shall we say, "reduction (or oxidation) potential" or can we use redox as passpartout?* I am oriented to say that is either reduction or oxidation, at least in a pedantic way.
Comment: The post title was a decent question. The text of the question does not make any sense. Also, what do you mean by "passpartout"? Only the signs differ between reduction potential and oxidation potential.
Comment: Ok but you have treated the term redox as if it is red... I am not saying you wrote something wrong. Just the question wasn't addressed, while it seems so for the answer by @Karsten Theis. Passpartout in the sense that often we indeed say or hear of redox potential instead of a more correct reduction (or oxidation) potential, especially when a value is then given.

Is redox potential a valid term?


What is a short exact sequence telling me?

Question: Let's take a short exact sequence of groups
$$1\rightarrow A\rightarrow B\rightarrow C\rightarrow 1$$
I understand what it says: the image of each homomorphism is the kernel of the next one, so the one between $A$ and $B$ is injective and the one between $B$ and $C$ is surjective. I get it. But other than being a sort of curiosity, what is it really telling me?
Comment: It tells you that $B$ is an [extension](http://en.wikipedia.org/wiki/Group_extension) of $C$ by $A$
Comment: oh, I like this
Comment: As a big picture thing, a short exact sequences are essentially arithmetic calculations where you're doing arithmetic with groups (and homomorphisms) rather than with group elements. To really understand the utility of an arithmetic calculation requires using them to do arithmetic calculations or even algebra.
Answer: As Jessica said in a previous answer, the set up initially tells us that in some sense $C = B/A$. To see this, since $A \to B$ is injective, and has image precisely the kernel of some map, we may identify $A \unlhd B$ as a normal subgroup. And this is precisely the kernel of a surjective map $B \to C$ so by the first isomorphism theorem, $C = B/A$.
However, the situation quickly becomes more interesting than this. For example, this situation clearly arises when we have a direct product of groups $B = A \times C$. Motivated by the simplicity of this case, we say that the sequence splits if $B \cong A \times C$. For a non-abelian group, this happens if and only if we can find a map $B \to A$ (think projection) such that the composition $A \to B \to A$ is the identity automomorphism on $A$. For an abelian group, we can say even more that the sequence also splits if we can find a map $C \to B$ such that $C \to B \to C$ is the identity. This happens more generally in abelian categories like the modules over a given ring. This Wikipedia page has more info...
In general we also care about such questions because in algebra and related topics we often find ourselves dealing with so-called long exact sequences of forms
$$... \to A_{-1} \to A_0 \to A_1 \to A_2 \to... $$
Where we know some of the elements of the sequence and some of the maps and would like to identify what the others are. In general any such sequence may be broken down into a number of short exact sequences, and in the best case we may split these sequences to nicely describe an unknown term in terms of the kernel and image of the surrounding maps. The first example that most see in my experience is the Mayer Vietoris sequence which arises in algebraic topology as a way to compute algebraic invariants of a space in terms of those of simpler subspaces.
Answer: This set up will tell you that, essentially, $C=B/A$. Think of the first isomorphism theorem.
In some cases, you get that $B=A\oplus C$ (see Wikipedia: Splitting lemma).
Comment: Actually, what you've stated is always true.
Comment: Yes, you're right. I was muddling two ideas. I'll edit my answer.
Answer: It's getting more interesting as soon the diagrams get more involved. For example: If the following diagram with exact rows commutes, and the outer columns are both mono/epi/iso-morphism, then the middle one is also a mono/epi/iso-morphism:
$$
\begin{matrix}
0\to &A&\to &B&\to &C&\to 0\\
&\downarrow&&\downarrow&&\downarrow&\\
0\to &A'&\to& B'&\to &C'&\to 0\\
\end{matrix}$$
Translating this statement fully into kernel/image lingo, would make it much less graspable.
Answer: "The kernel of $B \to C$" is often not a satisfactory description of a group. Having a group $A$ that it is isomorphic to (along with a given isomorphism) is very useful.
"The quotient $B/A$" is often not a satisfactory description of a gruop. Having a group $C$ that it is isomorphic to (along with a given isomorphism) is very useful.


How can I fix my worlds not saving?

Question: I have Minecraft PE. I made a cool world with good items and a nice house. I had to leave for school, but when I got home I got on my tablet and played Minecraft, my world was not there. Now every time I make a world and get off Minecraft, it is not there. What do I do?
Answer: There isn't a "fix" to your worlds not saving. Just make sure press "Quit to title" before closing the game to make sure it saves the world. Every now and then, the game saves itself but you can never be sure when this happens.
Answer: You need to make sure that you press "Save and quit" and the properly close out the application.
If you are on an android, press the back button until it asks you if you want to quit. If you are on an iOS device, double tap the home button, press and hold the Minecraft PE icon and then press the red X.

How can I fix my worlds not saving?