Prediction interval for Combined forecast of univariate time series

Question: I have made a combined forecast of a univariate time series. I used ETS, ARIMA and STL and take a simple average of these means and get a combined point forecast 12 months ahead.
My question is. How to calculate a 95% prediction interval for the combined point forecast?
Answer: One way is working out what the probability distribution of the mean exactly, which can sometimes be quiet difficult.
Another way is assuming that the mean is approximately gaussian due to the central limit theorem. Because N=3 and because you don't know the true variance of your sample, you can use a t-distribution.
In practice, calculate the mean and sample standard deviation, use N-1 degrees of freedom on a t-distribution percent point function (python/scipy has st.t.interval) and compute the 95% C.I. for your mean.
Source: https://en.wikipedia.org/wiki/Student%27s_t-distribution
Comment: Thank you for answer. I am wondering whether a simple average of the 3 prediction intervals are appropriate as a combined prediction interval for the combined point forecast


This organization's certificate has been revoked. IE 11

Question: This organization's certificate has been revoked.
Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server.
I try to fix this issue through Tools --->Internet options--->advanced ----->Under security click check certification revoked and publisher check box but still browser is not been responding the changes getting same problem
Did anyone has come across the same problem.
Answer: I am not sure if I understand your problem here, but you may want to try re-starting your Hub and Nodes with -trustAllSSLCertificates switch turned on. As the documentation says it "Forces the Selenium proxy to trust all SSL certificates.  This doesn't work in browsers that don't use the Selenium proxy."
e.g.
java -jar selenium-server-standalone-2.44.0.jar -trustAllSSLCertificates true -role hub


Upgrading from classic to hd

Question: Trying to upgrade. I can open my wallet in Multibit classic without entering a password. I have never needed a password to open it and don't remember ever setting one up. I certainly have none recorded. But I can't export a key without entering a password. I tried sending the contents of the wallet to a new wallet in Multibit-HD but I don't know how much to send to allow for the transaction fee. There does not seem to be an "empty wallet" option.
Answer: MultiBit developer here. You should be able to simply spend from your Classic wallet into your new HD wallet. Don't try moving private keys around - that's really easy to get wrong and is one of the reasons we wrote HD in the first place.
There are full instructions on upgrading on the MultiBit website: https://multibit.org/en/help/hd0.1/how-to-upgrade-from-classic.html
Answer: Well I'm not totally sure about the password situation but you can easily send a 1 cent transaction fee and send the rest of your bitcoin to another wallet if that is an option. You don't even technically need a transaction fee it will just take much longer for the transaction to be confirmed if you do not send a fee.
1 cent currently is ~ 0.00004 BTC

Upgrading from classic to hd


Every module over a field is free. Is every commutative ring whose modules are all free a field?

Question: Let $A$ denote a commutative ring. Then if $A$ is a field, we may deduce that every $A$-module is free. Does the converse hold? i.e. If every $A$-module is free, can we deduce that $A$ is a field?
Comment: [Here](http://math.stackexchange.com/questions/75866/every-r-module-is-free-implies-r-is-a-division-ring) the question was asked for the more general non-commutative case.
Answer: I would think so.
Let $0\neq x\in A$ a non-invertible element. Then the ideal $Ax$ is proper.
Now consider the quotient $A/xA$ as an $A$-module. Since $x\cdot\bar1=\bar 0$, it is torsion, thus not free.
Answer: If $I$ is a proper ideal of $A$ then $A/I$ is free by assumption, but any element in a basis will be killed by anything in $I$, so we must have $I = (0)$, and thus $A$ must be a field.
Answer: Tobias's and Andrea's answers are pretty much optimal for commutative rings. I'd just like to share a strategy that works for noncommutative rings as well.

For any ring (with identity) $R$, all right $R$ modules are free iff $R$ is a division ring.

Proof: Let $S$ be a simple right $R$ module. Then $S$ is free. Since it's simple, it cannot have more than one copy of $R$ in its decomposition into a sum of copies of $R$. Thus $S\cong R$ as right $R$ modules, and this shows $R$ is a simple right $R$ module. That immediately implies $R$ is a division ring.
Comment: Note that actually my answer also works for noncommutative rings, as long as one just lets $I$ be a left ideal.
Answer: Assume that $R$ is a commutative ring with $1$ whose every module is free. Let $I\subseteq R$ be an ideal. Note that $R/I$ is an $R$-module and therefore free. If $I\neq\{0\}$, then every element of $R/I$ is a torsion element (since we can act by any non-zero element of I to obtain $0$ in $R/I$). Since $R/I$ is also free, $R/I=\{0\}$. Therefore, $I=R$. So, the only ideals are $\{0\}$ and $R$, meaning $R$ is a field.
Answer: Assuming $R$ is a domain, then here is another approach:

Firstly, $R$ must be a PID, because an ideal that is not principal is not a free $R$-module.
Now consider $K$, the quotient ring of $R$, as an $R$-module, and note that $1_R \in K$ is a primitive element (ie. if $1 = ay$, then $a \in R^{\ast}$) and so there is a basis of $K$ containing $1_R$ - call it $\{1_R, v_1, \ldots, v_k\}$. Consider $v_1 = a_1/b_1$ with $b_1\neq 0$ in $R$, then
$$
a_11_R - b_1v_1 = 0
$$
which implies that $a_1 = 0$ whence $v_1 = 0$ - this is impossible.

So it must follow that $K$ is one-dimensional, and hence $K = R$.


metadata in Orfeo Toolbox Orthorectification

Question: I'm using Orfeo Toolbox to orthorectify a WorldView-3 Basic Imagery Product. The process seems very straight forward. I just input the image and a DEM of the area, and Orfeo gives me an orthorectified image, so apparently everything is very fine. However, I'm wondering whether the process is actually correct... how can I be sure that the software is actually using the information contained in the associated files (attitude file, metadata file, etc)?
Comment: Sorry, I dont find the option to include the DEM and RPC files in Orfeo (Geometry tool). Pease, review the attachment. ![enter image description here](https://i.stack.imgur.com/vsXXX.jpg)
Comment: If you have a new question, please ask it by clicking the [Ask Question](https://gis.stackexchange.com/questions/ask) button. Include a link to this question if it helps provide context. - [From Review](/review/low-quality-posts/132047)
Answer: OTB do include test for support of WV3 geometry. I supposed that the format is pretty much the same as WV2 which explain why the process run without errors. Nevertheless there is still a bit of work to check that the orthorectification is correct
Even if it's not a quantitative validation (sensor modelling validation can be tricky question) you should try to superpose the output image with Open Street Map or any georeferenced data over the same area to check the geometry.
Don't hesitate to give feedback about your experimentation on otb-users mailing list (google groups). The remaining work for a complete support of WV3 is probably not much in OTB in my opinion and starting the discussion on the mailing-list is a good starting point to gather ideas.
Regards,
Answer: Many thanks. When superposing a road network from Open Street Map, there is some displacement (few meters), but it is within the expected error and it seems that there is no other important geometric distortions. I mean, this displacement is approximately the same throughout the image and can be easily corrected with a small (x,y)-offset transformation.
I´ll give this feedback in the otb-users mailing list, thanks a lot.


Can I vertex paint with an image?

Question: I am vertex painting using Cycles, & I have set up nodes to plug the vertex colors into a shader & it paints on & works fine, renders etc, looks as expected. But vertex painting gives a brush color choice only - Question - is it possible to use an image bitmap instead of the brush colors? Or - is vertex painting only for colors? I made a material with an image, unwrapped my object's surface, but so far I can't find a way to use this image as the color source (apart from just putting this material onto the selected surface area).
Comment: I answered the question that is in the title ; however, I suspect your method is wrong, and I can't really understand your second question. What exactly are you trying to do ?
Comment: As thibsert said, Properties Panel-->Brush setting lets you select a texture. The brush color/color swatch is only used as an overlay. Select white if you don't want any overlay.
Answer: Under the brush settings, in Texture, click New. In the properties panel, in Texture/Image click Open, then locate your picture file. You can now use the picture as a brush.

Can I vertex paint with an image?


How to animate a growing plant with branches?

Question: I was trying to animate a plant. For that purpose I created a curve, gave it a bevel depth and animated start bevel factor, but then I got a problem - curves can't have branches. There are various ways to fake branches but I need them to start growing exactly in the moment when trunk reaches the branch height. Do you know how to make a plant with controlled shape to properly grow without animating all and every branch separately?
Answer: You'll need to do some manual tweaking and timing, no doubt. Automating this would make sense if you had a massive amount of plants to process.
I've used the following method when animating growing plants with branches which I've found relatively easy to do. Admittedly it was on 3dsMax, but I believe the same steps applies to Blender.
First off, I always work with a mesh. Then I build a quick rig/armature loosely following the branching of the plant. Usually automatic skinning works fine.
To animate it grow, I take the starting pose and scale each bone to zero. I flip the starting and ending keyframes so the plant grows instead of shrinks. And since every bone inherits the scale of its parent, you get a nice, gradually cascading effect.
Things to tweak at this point are the timing of when the branches start to grow (wait for the parent bone to grow to full size before beginning its own scaling, for example), and slight rotation of each branch.
Comment: Yeah, something like that I meant when said "... animating all and every branch separately", because I need a hell of a lot of branches. But anyway, thanks for the method, maybe its the only way...
Answer: Blender has no straightforward way to do this.
I think you would have to script this (automate animating each curve by checking its parent branches growth and only start growing when appropriate).
This is reasonably involved to do, but this kind of task is well supported by Blender's API (you have access to all data you need).
Comment: Never used blender scripting, so its a bit of a nuisance, but sounds interesting. I just don't see how can you make a single script to animate any number of branches. Maybe, if you can somehow define the trunk and then animate every curve that is crossing the trunk... I just don't know where to start.
Comment: Yep, a single script can animate any number of branches. You would need some way to detect which branches are parents and how they're connected. but its not so hard to do.


Data location specification and bytes32

Question: Why is data location not required to be specified for bytes32?
Comment: @FlorianCastelain In solidity, there are 4 types of data location: storage, calldata, stack and memory. Data location must be explicitly specified in solidity for arrays, bytes and structs.
Comment: Hello. Please give us more details about your question. What do you mean by "data location not required" ? What exactly are you talking about ? What type would require it ?
Answer: Whether or not you need to declare memory, storage, or calldata depends on if your variable is a "complex" variable or not. (See the note here.) This means things like structs and arrays. Simpler types are automatically assigned storage - see this question and anwser.
To answer fully, bytes32 will automatically be storage even without a data location declaration.
Comment: Thanks, that fully answered it!
Comment: `bytes` is a monster that probably should have gotten a different name to distinguish it further from the simple types like `bytes32`.

Data location specification and bytes32


When exactly does the auto-save save the game in Dark Souls?

Question: The auto-save system in Dark Souls saves quite a lot, but exactly how often does it save? If I was to force-quit the game, how much progress would I lose at any given time?
Comment: Funny, I was just about to ask a DS question. You can see the indicator flash quickly in the top right corner when it saves (it's very quick). I'd answer, but I don't have a specific time.
Comment: @Carcigenicate Well this kinda a "FYI" Q&A post :)
Comment: Ahh lol. Jumped the gun. Well, this is definitely good info!
Answer: The auto-save system basically removes any need for worry of losing any major progress. The game saves:

Any time you interact with something (talk to an NPC; pick up an item; rest at/leave a bonfire; open a door/walk through a Fog Wall; etc.)
Defeat an enemy
Gain/Lose Souls (i.e. Die)
Teleport
Open the Menu/Level Up/Manage your inventory or equipment
Quit the game
Get queued for an invasion/summoning (the game saves before phantoms show up; the moment the fog gates appear, regardless of whether or not the invasion/summoning is successful), as well as when they disappear.

The only times that you might lose progress, is if you accidentally quit early during a boss fight. Travelling away or quitting before receiving the souls/items from a boss may require you to restart the boss fight again - even if you have seen the boss die. The other is if you are simply running from one end of the map to the other without interacting with anything. You'd simply return to the place where you left off.


Hot water tap at work

Question: Many offices have a water dispenser (with hot water spout) or a hot water tap next to a sink. Is this hot tap Kosher? Assume for a moment that someone uses the tap to dispense hot water into a cup of non-Kosher instant soup or non-Kosher instant hot chocolate. Does the steam from the cup make the tap non-Kosher?
Comment: I don't think we are talking about the same thing.
Comment: In Ireland, water from the hot tap is usually considered non-potable anyway. You take water from the cold tap, and heat it in a kettle.
Comment: Trig, thanks, that's interesting. Here in the US, though, the idea is as a convenience to have instantly hot water for everything from making a cup of tea to washing dishes.
Comment: I wouldn't drink water from a hot tap, or water from a bathroom cold tap: that comes from a tank in your attic. The water's been sitting around for a while in not-perfectly-clean pipes and tanks. Kitchen cold taps come from the rising mains, and are generally safe to drink from.
Comment: I'd heard one rabbi say "you see the crust around the tap, that's from all the non-kosher food that splashed on it!" It's more than likely, at least in many cases, that the crust is instead mineral buildup from the water.
Answer: The Star-K advises as follows:

In general, these are permissible. If one witnessed a co-worker submerging the spout into non-kosher food, the urn should not be used. In many cases, however, one does not actually witness the co-worker placing the spout in the bowl but is concerned that it is a possibility. In those cases, one should make an assessment of the likelihood of this happening. If the spout is sufficiently far away from the tabletop so it would be unnecessary to bring the bowl up to the spout, one should simply wipe the outside of the spout and run a little water through it before filling a cup. If the spout is so close to the tabletop that a bowl would not fit easily without touching the spout, one should not use the urn. Regarding the steam rising from the bowl, for various halachic reasons, the spout remains kosher. In such a case, one need only wipe the outside of the spout and dispense some hot water that should be discarded and then take hot water or coffee for use.
Answer: You may use the water from the tap.
The Rema writes (YD 105:3):

אסור לערות מכלי שיש בו שומן כשר לנר דולק שיש בו חלב או שומן איסור
  ובדיעבד אין לחוש.
It is forbidden to pour from a utensil that contains kosher fats into
  a lit candle that contains non-kosher fats, but after the fact one
  should not be concerned about it.

This seems to be similar to your case. However, there are at least two independent reasons why your case can be permitted:

The Rema says that bedi'eved it is permitted, and taking water after the other person used it for non-kosher is a case of bedi'eved, not lechatchila. My basis for saying this is the Shach in the se'if before (se'if katan 5) who defines lechatchila and bedi'eved this way. Meaning that lechatchila in this type of situation means take precautions as if doing x will cause problems, but once x is done we don't see any issur whatsoever, and the thing may be consumed lechatchila.
More importantly, the details of the Rema's case are very significant - the hot item; the candle is on bottom. Therefore the basic rules of tata'ah gavar (for explanation see here starting from 3) are able to come into play and say that non-kosher flavor transfers. On the other hand your case is exactly the opposite - the bottom; the contents of the person's cup are cold (certainly not kli rishon hot). Therefore the Halachic rules of flavor transference say that there is nothing to be concerned about.

I've elaborated extensively on these points in this blog post.

Hot water tap at work


How do you know when you need to add more air in the tires?

Question: How much air is too little and you should add more for the safety and ease of your bike ride?
Answer: Look on the sidewalls of your tires, and you should see a recommended pressure range. If your tires are outside that range, you need more air. The lower end of the pressure range is good for soft ground like dirt or gravel or snow, where you need more traction; the higher end is best for roads, and will help you avoid pinch flats.
Answer: The short answer is: it depends on the tires.
If the air pressure is lower, there is more contact between the ground and the tire. This has the advantage of more grip (especially in rainy and/or icy conditions this can be nice), but the disadvantage of more resistance, making the cycling harder.
If the air pressure is higher, the advantage is making it easier, but the disadvantage is less grip.
In addition, if the pressure is low, the wheel can damage the tire, if the pressure is high, the ground can damage the tire.
In general the thin tires (such as on racing bikes) do require higher pressure then wide tires (such as on mountain bikes).
If you see the bottom of the wheel as cutting in to the side of the tire, then the pressure is definitely too low.
Answer: Simple answer is, they always need more air.  Tires leak, slowly, but they all leak.
If you are riding every day, you probably want to top them up every 2-3 days.  If you ride once a week, you need to top them up every ride.
Answer: Other looking at the sidewall, here are some clues that I use:

If the rim hits the edge of a pothole or uneven sidewalk when you go over it.
Learn the relationship between the feel at the thumb and the amount of pressure in the tire
For a given tire, too low can depend on what you want out of the tire and the conditions that you expect to ride in.
If you find it difficult to hold your line in a turn because your tires are not firm enough (in extreme cases the tire will roll off), you should increase the pressure.
Comment: If #1 or #4 are happening with regularity, you may be damaging your rims.
Comment: @neilfein true, except that I usually figure it out before I hit my rims hard enough to damage them. For #4, rolling a clincher tire is a pretty extreme case.
Answer: There are 2 ways to determine this. One is to use an air pressure gauge. The other is to squeeze the tire with your fingers.
Like Neilfein says above, first check the inflation specs on your tires.
Roughly....

Mountain bike tires = 35 - 65 psi
Commuter bike tires = 75 - 100 psi
Road bike tires = 100 - 120 psi

Ok, so here's something you can do. Using a pressure gauge, pump up your tires to the max pressure. Then, using your fingers, see how that feels. Now, let the air out, and pump up to the min pressure, and see how that feels. Also, do the same with a middle pressure. Now you have a range.
Once you are familiar with how that pressure range feels, you can either head off for your ride or add air. And of course, you can always use a gauge to check the pressure before each and every ride.
For casual short rides I just squeeze the tires. And it works. Beyond that, I get out the pump and top them off.


Block size is for Database or Tablespace?

Question: Forgive me I am just a newbie in the Oracle. I saw there is a db_block_size parameter which can be specified the block size for a database so that the whole database will be read and written data with the specified block size. But what make me confused is we can also specify block size for the Tablespace when we want to Create Tablespace. Please check the Block size clause. My question is are they contradictory? How could they both work in the same Database. Because the TableSpace belongs to a Database. Thanks.
Answer: db_block_size is the default block size of the database, but it does not necessarily mean all your tablespaces have the same block size, you can have tablespaces with different block sizes.
You need to define seperate cache areas for tablespaces with non-default block size. For example, if your db_block_size is 8192, and you want to create a tablespace with block size of 16384, first you need to specify a size for the "16K" cache with the parameter db_16k_cache_size, and after that you can create a tablespace with 16384 block size.
Comment: Hi Balazs Papp, Thanks your reply. So If I didn't specify block size when to create a tablespace. Will this tablespace use the db_block_size? Thanks.
Comment: @Joe.wang Yes, if you do not specify, then the tablespace uses the database default (`db_block_size`).
Answer: Tablespaces with different block sizes than the database exists because of transportable tablespaces, where you want to move the tablespace to a different database that has a different block size than the database you are moving the tablespace from (usually from an OLTP database to a data warehouse).
Although certain sites claim you can get a performance increase with tablespaces of different block sizes from the database, that is an unintended side effect (when it actually works out that way), and it should not be a consideration when designing a database.  Please see Ask Tom for more information.


Why we need to control for the interation of year and industry fixed effects?

Question: Normally, we control for firm and year fixed effects, but in some case I saw people control for the  firm along with yearxindustry or firm and yearxregion fixed effects.
Could you please hint me why they need to do so?
Answer: When you control for not just year fixed effects but instead year-region or year-industry it adds flexibility.
The year fixed effects controls in a flexible manner for the time-trend and is more flexible - less restrictive - than for example assuming that the time trend is for example linear $a \cdot t$, second order polynomial $at + bt^2$, exponential $exp(at)$ ect.
Nevertheless, year fixed effects are still restrictive compared to year-region or year-industry because the assume that the time trend is the same for all regions or for all industries instead of allowing different regions to follow different trends or different industries.
Consider for example this plot here

and assume that it show the average wage of women (red) and the average wage of men (black) over time.
We then conclude that the gender wage-gap is closing. However, someone then points out this is not really the case because although female workers on average over time get the same as male workers this is simply because female workers have changed from predominantly working in the low-wage industry to be working in the high-wage industry.
Offcourse you are sharp and you run a regression controlling for industry
$$\log y_{it} = \beta_0 + \alpha \cdot \text{male}_{it} + \lambda \cdot  \text{industry}_{it} + \delta_t + \epsilon_{it}$$
which is a good idea and for the simulated data used to generate the plot above you then get an estimate $\hat \alpha = 3.05$ clearly showing that male workers are given more in wage than female workers.
However, the true $\alpha$ is actually even larger and equal to $4$ so you are still underestimating the degree to which female workers are discriminated on the labor market.
In this example this happens because:
Over time the wage in the high wage sector increases faster than the wage in the low wage sector. So while women over time changed to the high wage sector you are undercontrolling for the sector effect because the early year with a small difference between the sectors bias the sector effect downwards.
In this case what you should have been doing to get an unbiased estimate was to run the regression
$$\log y_{it} = \beta_0 + \alpha \cdot \text{male}_{it}  + \lambda_{st} + \epsilon_{it}$$
where $\lambda_{st}$ is the sector-time fixed effect.
You can simulate this example in R using the following code
<code>library(data.table)
library(lfe)
N1 <- 1000
N2 <- 1000
N <- N1+N2
T <- 10
b0 <- 1

# a1 is the true gender effect
a1 <- 4

gender <- rep(c(rep(0,N1),rep(1,N2)),T)
a2 <- rep(1:T * 2,N)
dt <- data.table(id=rep(1:N,each=T),time=rep(1:T,N),gender=gender)
setkey(dt,time,gender)
industry <- c()
for (t in 1:T)
    {
        temp1 <- sample(c(0,1),N1,replace=TRUE,prob=c(0.5,t/T))
        temp2 <- sample(c(0,1),N1,replace=TRUE,prob=c(0.5,0.5))
        industry <- c(industry,temp1,temp2)
    }
dt$industry <- industry
setkey(dt,id,time)
dt$log_y <- b0 + a1*dt$gender + a2*dt$industry + 0.3*dt$time + rnorm(N*T)
foo <- dt[,.(m_wage=mean(log_y)),by=.(time,gender)]
plot(1:T,foo[gender==0,]$m_wage,ylim=c(0,20),col="red",type="l")
points(1:T,foo[gender==1,]$m_wage,type="l")

dt$i_time <- interaction(dt$time,dt$industry)
# Regression with industry dummy

summary(felm(log_y ~ gender+industry|time,data=dt))
#          Estimate Std. Error t value Pr(>|t|)
# gender    3.05645    0.04164   73.41   <2e-16 ***
# industry 11.13346    0.04215  264.12   <2e-16 ***

# Regression with industry time fixed effects
summary(felm(log_y ~ gender |i_time,data=dt))

#        Estimate Std. Error t value Pr(>|t|)
# gender  4.00873    0.01443   277.7   <2e-16 ***

savePlot("male_female.jpg",type="jpg")
</code>
Comment: You are welcome. Unfortunately SAS i dont know. There is also an accept button you can press if you find this answered your question.
Comment: I can try. But I think you should make this follow up question in a seperate post. But $\lambda_{st}$ is short hand notation of $\sum_s \lambda_{st} 1[(i,t) \in s]$ where $1[(i,t) \in s]$ is indicator of individual $i$ working in sector $s$ at time $t$. So it is just a factor variable with levels being sector-time groups. I ignore the dummy variable trap. But this may not necessarily clean up any confusion you are having.
Comment: Thank you for your clear explanation, I am using SAS so I am wondering if there is any SAS code available for this example. Thank you.
Comment: I am curious about one point: where λst is the sector-time fixed effect. So at that time, can you please help me to clarify what exactly λst stand for ? Thanks.
Comment: Thank you for your clear explanation. I raise another question here cited your answer as mentioned, I am wondering if you can have a look on that. https://quant.stackexchange.com/questions/64055/what-can-we-explain-while-adding-regionyear-fixed-effects-the-sign-flip


after ldaps config, ldapsearch does not display entries

Question: I configured ldaps by refering http://linuxtechres.blogspot.com/2010/04/how-to-configure-ldaps-or-starttls.html.
after that when I try to  ldapsearch, it wont display any resulsts.
entries are there in ldap, as I will get error if I try to ldapadd them .
If I remove TLS related info from ldap.conf and slapd.conf , ldapsearch works nicely and display all entries.
Can someone help please?
Answer: Do you have some minimum level of confidentiality required in your config file?  Also the way the ACLs work is that they stop processing after the first hit (in general) so if you have an ACL on a specific user type that is extremely limiting that may be what causes your situation.  The admin account can always see everything in case you do mess things up.
Answer: Probably late for this, but... Have you tried the ldapsearch/ldapadd option "<code>-ZZ</code>"?
Answer: What you want to do is look at the slapd.log file and see what error the OpenLDAP server is returning when you try to connect.  Then you will have a hint of where to go next.


Adjective for someone who's quick and easy to become close to

Question: I'm looking for a 1 word adjective to describe someone who very easily builds close and personal relationships with other people, in a way that almost seems magical to everyone else.
Charismatic is close, but not quite, as this person doesn't necessarily inspire devotion or admiration, just quickly becomes people's best friends.
The closest word I've found is "palsy-walsy", meaning someone friendly in an intimate/hearty way. It doesn't quite describe the effect it has on the people around them though.
Comment: Melody Liu, you seem to be mixing several different ideas.

"Charismatic" does match what you described and doesn't at all suffer from "inspiring devotion or admiration." Meanwhile, "palsy-walsy" is almost the opposite of what you asked about; it always describes a *semblance* of friendship with no substance.
Answer: Accessible is often used to describe someone who others find easy to talk to or open up to.  Webster describes it as easy to speak to or deal with.
Approachable has a similar meaning: easy to meet or deal with (and "accessible" is used in the definition) Webster
Answer: Amiable charisma can be used in the context provided by you in your explanation.
Amiable (adjective):

friendly, sociable, and congenial. Example: "an amiable host."

Charisma (noun):

A special magnetic charm or appeal. Example: "the charisma of a popular actor."

"Amiable charisma" is used in various books to describe a person who has friendly disposition with magnetic charm.
1) THE COMMON CASE OF DAMIAN VONGCIR
By Uyi Eguavoen.

When Damian first came to Landmark, it was Macaulay Etiebet who was so often talked about, and it was his amiable charisma, his stylish sophistication, and appealing elegance that got the most mentions.

2) 9 Sisters Cursed Since Birth: A Corrupt Family Drowning in Their Deadly Sins By Na 'Veah Rose

I describe Lannah as a charming person, but she can be a victimizer as well. Meaning -- she has the potential of intriguing and enticing people with her amiable charisma.

3) Born Under Punches By Martyn Waites

It was clear to Larkin, even in the short time he had been there, that Tony Woodhouse was popular with both staff and clients. He had an easy, amiable charisma people responded to.
Answer: I would suggest the word magnetic:
https://www.merriam-webster.com/dictionary/magnetic

possessing an extraordinary power or ability to attract; a magnetic personality

The synonyms for "magnetic" cited here are also a fantastic collection to choose from to describe a person who easily draws others in and manages to connect with them in a deep and meaningful way.

alluring, appealing, attractive, bewitching, captivating, charismatic, charming, elfin, enchanting, engaging, entrancing, fascinating, fetching, glamorous (also glamourous), luring, seductive

Update (8/7/2018): Another suggestion could be gregarious, which can indicate someone who easily converses with others and is comfortable to be around (see https://www.merriam-webster.com/dictionary/gregarious, especially "b"):

a : tending to associate with others of one's kind : social gregarious animals
b : marked by or indicating a liking for companionship : sociable is friendly, outgoing, and gregarious
c : of or relating to a social group


What games are similar to Risk?

Question: Are there any other board games that have similar game mechanics to Risk?
Comment: "Are there any other board games that have similar game mechanics to Risk?" In what way? Which mechanics are of most interest to you?
Answer: I generally think of Axis and Allies as being like advanced Risk.  Also there are all of the different Risk clones, 2210, LoTR, Star Wars, Godstorm and others which introduce slight variants in maps and rules.  Of those I'd recommend 2210, but if you can handle the complexity, which isn't bad in the grand scheme, Axis and Allies is the way to go.
Comment: I'd argue Risk isn't that well balanced either - perhaps it's a good match ;)
Comment: Once you get into the order and mindset of how to resolve turns, Axis and Allies isn't that complex. Although not a perfectly balanced game, it really is a lot of fun when playing with 3 or more players.
Comment: @Powertieke: Bidding in Axis & Allies allows for a more balanced game. In short, each player writes down a bid as to how many IPCs (or extra troops or whatever) they'd want to be "compensated" in order to play the Axis powers. The person with the lowest bid becomes the Axis.
Comment: Risk is atrociously balanced and far too luck based for my tastes.  A&A is slightly more reproducible, balanced and complex and therefore in my mind a better game, but that's just my opinion.
Answer: Diplomacy is a similar game in that its aim is to conquer other players land. However it removes the dice and the element of chance, replacing it with face to face negotiation (making it a much better game IMHO).
You can play it online for a quick taster. There are also lots of other web based learning resources.
Comment: Diplomacy is really a very different game from Risk.  It's (to borrow an expression about poker) a people game played with a board and rules rather than a board and rules game played with people.
Answer: Shogun is another similar game. The combat is different in this game (you are not using dice at all) but gathering resources and conquering other provinces (which act like countries in Risk) has the same basic principles.
Comment: +1 for reminding me to dig my Shogun box out of the loft. I seem to remember there was a semi-decent PC conversion (*spit*) a few years back.
Comment: @Jon Hadley If I'm thinking about the same game as you are (Shogun: Total War), I don't think that game shares anything but title with the board game.
Comment: I thought it at least had the board game mechanic as an option to move your troops, but now you mention it, I do remember that it was more of a battle simulator than anything else.
Comment: @RaYell There are at least 4 different Shogun games - The one published by Queen Games looks like risk with cubes, but is a civ-game in play. The Milton-bradley one, renamed Samurai Swords, uses d10's and is really an Axis and Allies variant more than a risk variant. Neither of which is the same as Shogun: Total War.
Answer: I really like Risk 2210 A.D..  Basically a faster, more Aggressive risk (also more luck and less strategy, but this does not take away from the fun of nuking a continent :))
Quest for the Dragonlords also plays a little like risk, but, to be honest, fails miserably at being any fun to play.
Answer: History of the World is played much like Risk.  There are 7 epochs.  During each epoch a player takes control of a different empire from the past.  They expand and conquer as much as they can (this part plays out very similar to Risk).  Next epoch they play a new vibrant empire.
Scoring is based on area control at the end of each player's turn.
Last year a new edition was released called, A Brief History of the World which is supposed to play to completion quicker.  I haven't yet tried it.
Answer: There is also Dust, which is set in an alternate World War II. There you have mechs and tanks, submarines and destroyers, bombers and fighters. New additions also include character-based powers, fortified positions and capitals. Unlike vanilla RISK, it uses a VP track to determine victory.
One of the interesting part of the combat is that tanks soak damage before mechs, fighters soak damage before bombers and destroyers soak damage before submarines (If I recall correctly). Mechs, Bombers and Submarines provide more offense in the game
The official site for the game is here.
Answer: How about Twilight Imperium. We always play and when I explain to someone who is not into the scene what it is I always end up saying:"Ok, do you know Risk? Well it's like that but more complicated".
But I guess there are loads of game that then qualify as advanced Risk :).
Comment: Awesome game, but absolutely nothing like Risk.
Comment: You build units and try to conquer territories by fighting using dice. Furthermore, everyone receives a secret objective which when completed will (help to) win the game. That pretty much describes Risk, but is also true for Twighlight Imperium right? But it's true that with that definition of "like Risk" there are a lot of games that qualify.
Comment: Base mechanics, like 'roll to hit' and Victory Points allready make it al very different beast. But I agree that more people should play this game.
Answer: Ozymandia is simultaneous Risk, simplified to its essence.
Answer: I used to play Samurai Swords (also known as Shogun) as a kid. It's a lot like Risk, with several unit types, more complex battles, and more territories. It takes forever though.
Answer: I'm not sure if this is what you're looking for, but there are various Risk variants that use exactly the same rules and mechanics, but on a different board. I've got the Lord of the Rings and Star Wars variants, and there are others. As far as I can tell (from the LOTR and Star Wars verions) they normally/often have some extra (and optional) themed rule and unit variations, which, combined with the new map topology, can keep it interesting if you're bored of classic Risk.

What games are similar to Risk?


What is this small, evergreen perennial in zone 6b?

Question: This is 2 stems, each with 3 leaves.  The leaves are thick and stiff with serrated edges.  The leaf is about 2".  The whole thing is about 2" high.  A few of these have popped up in the garden. This one has been here for about 3 years and has only grown this big.  I'm in zone 6b in Pennsylvania.  In the woods.  I have not seen anything around that looks anything like this.  Any ideas?
Comment: I've grown many plants from seed, some just for fun like citrus seeds. Every now and then, a plant will develop two true leaves; not cotyledon (seed leaves) but not grow any further. When I've checked, there is nothing - no tiny growing point - between the two stems that show a new branching stem developing. So now and then a dud grows that stays like that. I've kept some for months to see if anything happens. It doesn't but the tiny plant doesn't die either. Perhaps that's what the 3 year old is.
Comment: That little thing is 3 yrs. old? ... Well we know it can't be a weed. (just kidding)
Comment: Looks rather like a Hellebore seedling to me, but I can't think of any plant that would just look like this for three whole years, without increasing growth, losing its leaves or flowering
Comment: Do the others that have popped up have the same configuration of 2 stems and 3 leaves on each stem? Are they 5he same size as this 3 year old one?
Comment: I have to agree with you about being a helebore. I also don't understand why it isn't growing.  I went out to look at it again today and it's probably 3" off the ground.  The others are the same, one stem and 3 leaves but tiny.  I have babies under the mother plant that have grown so much in 2 years and they look just like a full grown hellebore.  I looked under the mother plant and to my surprise I did see a tiny 3 leafed one so I'm betting you ar right.  Thank you so much for your help. You led me in the right direction.
Comment: Wow, very interesting. Thanks a lot. I'll leave it there until I'm sick of looking at it.....or it does something. LOL
Answer: That's a young helleborus (Lenten Rose). If the conditions are off, they can take a very long time to settle in. Probably a seedling. In zone 6b PA, they are evergreen and old leaves don't die back until new ones have formed. If you want to grow them, transplant to a shady, well drained spot with high organic matter levels, and keep it watered. They are nitrogen suckers but too much can cause them to lodge.
Comment: Thanks so much. It's in partial shade but I'll move it to all shade. I appreciate your answer.


Does anyone know what is the science behind maturing?

Question: Once upon a time I did a little science at Uni. I'd now be really curious to understand a bit more behind the amazing difference between a freshly brewed beer and one that's matured on yeast for some time. Anyone found any interesting articles, links or know a bit themselves?
Answer: Amateur and scientific interest in beermaking is increasing, but it is a much younger subject than that of winemaking. I would direct you to research done on wine maturation for an answer to your question. Keep in mind though, that strong scientific research will likely be limited. Any huge breakthroughs discovered by a company's internal lab would probably be kept as a trade secret.
Some basic internet starting points:

Wikipedia's winemaking article -- this discusses secondary wine fermentation at a pseudo-scientific level
Wikipedia's article on wine ageing -- this article has a lot of information in it at a lot of different levels; check out the external links as well.

As for stronger research, there are a few references in those articles, as well as external links; such resources may point you to others. Additionally, a Google Scholar search for wine maturation shows some good initial results. A similar search for beer maturation looks really scientific.
Good luck!
Answer: This is an interesting question, and a similar one was asked here. However, it was not answered definitively ...


Driving High-Power RGB LEDs

Question: I would like to use a 30W RGB LED that is in common-anode configuration.  The issue is the voltage ranges for the LEDs are different, 20-24V for red, and 30-36V for green and blue.  Is it possible to run the red led at the same time as the blue or green?  If using PWM w/mosfets you still get the full 34V across the red LED I'm assuming that's not going to work.
Answer: One way is to use a single 36 V power supply, then essentially a small switching power supply for each LED to regulate the current thru each LED separately, but driven from PWM.
Here is what the circuit for each LED would be:

When the switch is closed, current builds up linearly thru L1 and therefore thru the LED.  When the switch is opened, the current continues thru the LED, L1, but now thru D2.  The current will now ramp down linearly.
With fast enough PWM there is little difference between the maximum current at the end of the switch closed time, and the minimum current at the end of the switch open time.  The PWM duty cycle then controls the average current thru the LED with minor ripple at the PWM frequency.
You probably want to use a PWM frequency of a MHz or more.  For extra filtering, add a ceramic capacitor from the LED cathode to ground.
Comment: thanks this looks promising, I'll have to design something in a circuit simulator.  Why do you suggest MHz frequency range?  I suppose to get smooth output as well as fast response to brightness changes?  I'm not sure if most microcontrollers can output 3 independent PWM channels at MHz frequencies are you aware of any info on this?  Thanks.
Comment: @peri: Higher frequency allows for a smaller inductor.  The inductor current will go down rapidly when the switch is off due to 30 V or so across it in reverse.  A cap from cathode to ground or across the will help a little.  Some of dsPIC series have a special high speed PWM module that can do nearly ns resolution.
Answer: All LEDs can be driven from the same voltage source.  Each LED should be driven by a separate constant current source LED Driver.
You did not specify the LED part number or the current which makes it difficult to help.
There are very few RGB LED driver chips with 36V out.  You could take a triple output RGB LED driver and add 3 MOSFETs LIKE THIS.
This is a simple inexpensive ($15 off the shelf) triple output LED driver from SparkFun (1 channel shown).

Full Schematic

This would be a good solution as it has a separate Vin for the Green.
It has a Vin max of 30V and will not work with your LED.

Driving High-Power RGB LEDs


Help: only 1 out of 36 exposure 35mm film was developed

Question: I am a complete beginner film photographer.
I just sent my 35mm film to be developed and only 1 picture was returned to me.
Whilst I am a beginner, the camera is half automatic and a green light showed for some photos. So I know I didn't completely mess them all up.
So I'm confused to why they didn't develop.
Is this a problem with the camera?? Or me?
Comment: Re, "is this a problem with the camera? or me?" You have not provided enough information for anybody to answer that question. A good first step toward improving your question would be to tell us the make and model of the camera.  Maybe somebody here is familiar with it and could suggest some things to try. Likewise, what kind of film? Where did you get it? How old is it?You also could say something about what steps you have taken to learn about film photography in general and, how to use your camera in particular.
Comment: How do the negatives look like? If you did not get the negatives in return, then consider this the first lesson, to never use the that service again.
Comment: I second the previous commenters. One more thing... just on a teminology point, which is always important when trying to fix something... you said that only 1 exposure was "developed". I am sure they were _all_ developed. You just received 1 picture back. By the way, did you receive one single print? Or was it one single digital scan that you got back? (In my experience, they won't print photos that are just _entirely_ black. So really you are trying to figure out why the photos were not actually exposed - could be an unremoved lens cap, incorrectly loaded film, or malfunctioning old camera.)
Comment: Following @KaiMattern question...if you did get the negs back, are they completely clear or is there something there? Or maybe completely opaque? Do the edges look uniform and can you see the frame numbers? Where was this one shot in the roll - first, middle, last?
Comment: Hello! Did you ask your developing service yet and asked whether they received all photos or if there was a problem?
Comment: Please describe what camera you used and how you loaded the film before shooting.
Answer: First. Every time you send something to be developed ask for the full film to be returned, even if all of it is messed up.
This will help you diagnose what is happening.
If you have all the film and you only have 1 print, you need to analyze the negatives.
Here is an example on a light leak on the film: These SLR developed photos are bad. Is it mine or the photolab's fault?

Is it actually exposed?
Could it be that the film got stuck?
Is the camera actually working? Probably the curtain never opened.

It is a bit difficult to know without having the film, but you can see if the camera is working using it with the back door open. You should see the courtain actually opening and the film gears actually rolling.


Do I have to pay tax both in NYC and England?

Question: I work in London for an English company. I will move to NYC and keep working for the same English company for a few months doing researches to open a new business, and my boss would like to keep paying me on my bank account in the UK.  Will i have to to pay taxes to both countries? Can anybody tell me how does it work in NY, please? thank you so much
Comment: http://www.hmrc.gov.uk/international/special-jobs.htm   http://www.hmrc.gov.uk/international/tax-return.htm
Answer: There are more issues involved here: US Federal tax, UK-US tax treaty, NY State tax and NY City tax.
I suggest getting a professional advice here, since the treaty may alleviate some, but not all, of the tax concerns.
Without the treaty - yes, you'll pay both the US (including the Federal, State and the City) taxes and the UK taxes in this scenario.
Answer: Yes, the IRS and the state and city of New York will probably all want a bite of your NYC-source income.  Your employer should have a process for dealing with withholding and may offer assistance in filing taxes.  One important question is the length of your stay (less than 183 days?) and other factors that will influence tax residency (which matters for your non-US income).
It sounds like you have general questions about this issue.  You can refer to IRS Publications 515, for nonresident aliens, and 519, for aliens generally, to get answers to technical questions.  Page 2 of 519 may be particularly helpful.  You may also wish to consult the UK-US Tax Treaty (and protocols and explanations), perhaps in consolidated form.
It may seem overwhelming, but many international and trans-Atlantic companies offer services to their employees to handle the tax aspects.  You should be able to discuss this issue with an administrative person at your employer, including any tax advice they will procure for you (i.e. an accountant or preparer) and any withholding they anticipate.
Comment: Foreigner in their first year in the US must use professional advice. Unless you're a student with no domestic or foreign income and no savings at home, you're bound to make mistakes that can cost tens of thousands of dollars. Americans prey on foreigners not yet aware of all the traps and pitfalls.
Comment: Agreed, advice is indicated.  Companies may provide that professional advice to their employees.  I had US friends working abroad and their employers provided both tax filing assistance and I believe gross-ups for extra tax (but not sure re VAT).


Resources on stress, tone and pitch evolution

Question: I am interested in the stress, tone and pitch (STP) aspects of historical linguistics. How do phonetic and other types of changes affect STP changes? How do languages end up with entirely different accentual systems? An example of that (according to Wikipedia) is from PIE to late Proto-Germanic with a transition from pitch accent to predictable stress accent.
Answer: You might try the Oxford Bibliographies entry on tone, by Remijsen, if you can get access. There is a section on tonogenesis, though that is the opposite of the historical trend that you are asking about. As far as diachronic change is concerned, there is not much written about tonoexodus, but this article by Ratliff could be helpful. Change from tone to non-tone languages occurs in Bantu and Atlantic languages. If you are specifically interested in so-called "pitch accept", you might want to look at the literature on Japanese and Basque, or dialectology of continental Scandinavian, Baltic or South Slavic.
Comment: Thanks! Even though this was not exactly what I was looking for, it gives me more places to look for answers :D


Etymology of "snob"

Question: Some dictionaries mention an origin involving shoemakers...  But I can't say the link is straightforward, really.
Answer: http://www.etymonline.com/index.php?search=snob&searchmode=none

snob
      1781, "a shoemaker, a shoemaker's apprentice," of unknown origin. It
  came to be used in Cambridge
  University slang c.1796 for "townsman,
  local merchant," and by 1831 it was
  being used for "person of the ordinary
  or lower classes." Meaning "person who
  vulgarly apes his social superiors"
  arose 1843, popularized 1848 by
  William Thackeray's "Book of Snobs."
  The meaning later broadened to include
  those who insist on their gentility,
  in addition to those who merely aspire
  to it, and by 1911 had its main modern
  sense of "one who despises those
  considered inferior in rank,
  attainment, or taste."

http://www.oxforddictionaries.com/page/originsnob

People often claim that this word
  originated as an abbreviated form of
  the Latin phrase sine nobilitate,
  meaning 'without nobility' (i.e. 'of a
  humble social background'). Various
  accounts of the circumstances in which
  this abbreviation was supposedly used
  have been put forward: on lists of
  names of Oxford or Cambridge students;
  on lists of ships' passengers (to make
  sure that only the best people dined
  at the captain's table); on lists of
  guests to indicate that no title was
  required when they were announced.
The theory is ingenious but highly
  unlikely. The word snob  is first
  recorded in the late 18th century as a
  term for a shoemaker or his
  apprentice. At about this time it was
  indeed adopted by Cambridge students,
  but they didn't use it to refer to
  students who lacked a title or were of
  humble origins; they used it generally
  of anyone who was not a student.
By the early 19th century snob was
  being used to mean a person with no
  'breeding', both the honest labourers
  who knew their place, and the vulgar
  social climbers who copied the manners
  of the upper classes. In time the word
  came to describe someone with an
  exaggerated respect for high social
  position or wealth who looks down on
  those regarded as socially inferior.
It's quite possible that the phrase
  sine nobilitate may have appeared in
  one context or another, but it is
  difficult to see why it would have
  given rise to a word for a shoemaker.

PS: many of google books from 18th century seems to OCR the word such as snob making the NGRAM viewer give false positives
Interesting link to a book from 1840 -
http://books.google.com/books?id=Em0qAAAAYAAJ&dq=%22snob%22&pg=PA73#v=onepage&q=%22snob%22&f=false
Answer: I've heard from different sources that snob is short for latin "sin nobile" (or "sin nobilitate" ?).
In high-end colleges, pupils which were not of a noble family had "s. nob." written close to their names.
And they gained the reputation of trying to mimic, in an outrageous way, the habits of "true nobles"
Comment: Have you ever noticed, when there's an folk etymology that involves an acronym before about 1940, it's invariably untrue?  By way of example, see "For Unlawful Carnal Knowledge" or "Port Out, Starboard Home".
Comment: I'm happy to stand corrected on this topic. The folk etymology I reported always looked suspicious to me.
Comment: There are old noble-title families that have used the 's.nob.' reference for longer than indicated in other answers.  Hopefully one of them can be coaxed to document this
Answer: I came across the snob entry in John Ayto's "Words Origin - The Hidden Histories of English Words from A to Z", which I quote here in extenso, just for the record although there are several valuable answers already.

Snob originally meant a 'shoemaker'.
  Cambridge University students of the
  late 18th century took it over as a
  slang term for a "townsman, someone
  not a member of the university", and
  it seems to have been this usage which
  formed the basis in the 1830s for the
  emergence of the new general sense
  'member of the lower orders' ('The
  nobs have lost their dirty seats – the
  honest snobs have got 'em', proclaimed
  the Lincoln Herald on 22 July 1831,
  anticipating the new Reform Act).
This in turn developed into
  'ostentatiously vulgar person', but it
  was the novelist William Thackeray who
  really sowed the seeds of the word's
  modern meaning in his Book of
  Snobs 1848, where he used it for
  'someone vulgarly aping his social
  superiors'.
It has since broadened out to include
  those who insist on their gentility as
  well as those who aspire to it.
As for the origins of the word snob
  itself, they remain a mystery. An
  ingenious suggestion once put forward
  is that it came from s. nob.,
  supposedly an abbreviation for Latin
  sine nobilitate 'without nobility',
  but this ignores the word's early
  history.
Answer: The NOAD reports the following note about the origin of the word.

ORIGIN late 18th century (originally dialect in the sense 'cobbler'): of unknown origin; early senses conveyed a notion of "lower status or rank," later denoting a person seeking to imitate those of superior social standing or wealth. Folk etymology connects the word with Latin sine nobilitate, "without nobility", but the earliest recorded sense has no connection with this.
Answer: Curious about this shoemaker origin, I put on my Google goggles and found an interesting letter to the editor in a 1762 issue of London Magazine from a Jeffery Snob, shoemaker. Not sure what to make of it. I've thought of several possibilities:

It's just a strange coincidence.
The letter writer anonymized himself with a pseudonym relating to his trade.
It's a fake letter written so the editor could freely editorialize via his fictional Snob.
Ol' Jeff was not only real, but went on to become London's greatest cobbler thus giving us eponymous snob.

If 2. or 3. is the answer, then it's a use of snob=cobbler 19 years earlier than Etymonline has. But I'm sure curious if it's an actual surname. I couldn't find any other examples of folks named Snob other than in a song from 1798, "Doctor Jeremy Snob," where the play on the last name is evident:

I not only patch up your Bodies; But Soles I can likewise renew.
Comment: +1. Nice catch anyway!  The point to clarify is indeed whether 'Snob' is a real surname.  If not then it should mean that your second hypothesis is the most probable (and etymonline or whoever they took the etymology from) did not get to the bottom of it.  Quite possible, given that Google book is a recent tool.  If 'Snob' *is* a real surname then you might be on to something.  Although the match shoemaker/snob seem to have taken root in Cambridge, not in London.
Comment: I must say I also enjoyed very much the reading of the previous letter to the editor in that link you provided, about the tale of hedgehogs being prevented from having intercourse with the cows to preserve the quality of the milk...
Comment: @Alain: Thanks. If you liked the hedgehogs, you should try Ngram-ing the f-word sometime and then peruse all the pre-1820 mis-scans of _suck_ with its medial _s_, and read them as _f_. Hours of fun. (Not that I've ever done fuch a thing.)
Comment: S'nob= "Is Nobody" (for a shoemaker, who probably did not have a formal education, instead of "Anonymus" he preferred call himself as "Is nobody" using a slang formula). But Jeremy could be anyone, what made the difference was the "lastname" which take us to a "reference" of "pertaining to". In spanish would have been "Don Nadie".

Etymology of "snob"


Are these logos too similar?

Question: Hi there after finishing the logo for a sports clothing brand I thought it was too similar to something and I went looking and found this USAF logo, what do you think? The Bulldozer logo is meant to look like a bull, and the USAF logo is wings.
Are they too similar to use?
 -----VS-----
Comment: Side-stepping the actual question, although the etymology of "bulldozer" does go back to "bull", if you say "bulldozer" to somebody, they think "earth-moving equipment", not "male cattle."
Comment: Arc the bulldozer text around like the usaf text to make it more similar :P Honestly, I dont think the usaf owns shapes. I personally think your logo is fine, but im not a lawyer.
Comment: Honestly, I think it looks a bit like a Romulan Bird-Of-Prey starship...
Comment: To me it doesn't look like a bull or a bulldozer ...but it does resemble, a bit, the AF logo.
Answer: Simple answer...no. While they share similar overall form, they are clearly different both in concept and execution.
Unfortunately, neither Matt nor myself are correct. It's really an opinion based question.
Will the airforce sue you over your logo? Highly unlikely. For starters, I doubt the two companies are competing. I don't see any intentional attempt to mislead the consumer. The concepts are quite different. I could go on.
Answer: For me when I look at your logo at a glance and from a distance I would say yes.  If I look at your logo while driving down a road when its on a sign and not reading what it says it would remind of the air force.    Look at them from a distance:

Some ideas to improve it:

Change the direction
Fill instead of outline some areas
change from a bird like appearance

The bigger question you should ask yourself is how does that symbol reflect Bulldozer Aesthetics.  Also, you spelled it Asthetics when spell checker tells me it should be Aesthetics

Are these logos too similar?


How can I make my options in an array and store theme in WP options one DB row?

Question: I am making a theme with theme options but for customization, I have completed my theme options more than half. Suddenly I have triggered one problem and that is I have checked my wp_options DB I have noticed that there are separate rows for each and every option I have at least 20 options for my theme and each option have makes the new row record in wp_options table I want to know that is there is any short way to convert my whole of my options in an array and store that in one row.
Comment: Use customizer option like `my_option[option1]`, `my_option[option2]` which store all values in `my_option`. Make serve you have selected customizer storage type option.
Comment: @maheshwaghmare can you give me any example.
Answer: It is trivial to store an array of options in WordPress — just pass an array to option functions. :)
The downside is that it will be stored in serialized form, which isn't friendly for SQL queries. That matters more for other APIs, such as meta data, than options.
Converting is up to you, you will need to adjust your code to work with and store an array.
Comment: is it also possible with https://codex.wordpress.org/Creating_Options_Pages example 3. I just want to know is it possible to make changes in it
Comment: Not sure on top of my head, Settings API is considered one of the more clunky APIs and it's quite typical for extensions to skip using it entirely.


Why don't kohanim eat terumah nowadays?

Question: Terumah is a tithe that is given to kohanim. I have been told that kohanim are not allowed to eat terumah nowadays. Is this true? If so, why not?
Comment: Why should they? How do you know they don't? Please try to put a bit more effort into your questions than one run-on sentence. Did you try googling for answers? What did you find lacking in what you found?
Answer: The kohen needs to be in a state of taharah (ritual purity) to eat terumah. Since without having a parah adumah (red heifer needed to eliminate the effects of the impurity of connecting with a human carcass) it is not possible to be in a state of taharah nowadays, the terumah is not eaten.
Rambam Sefer Zeraim Trumot chapter 2 halacha 14

Terumah [must be given] to a priest whether it is in a state of ritual
  purity or not. Even if all the grain or the wine became impure before
  [terumah] was separated, he is obligated to separate the terumah that
  is impure and give it to a priest, as [Numbers 18:8] states: "And
  behold I have given you the watch over My terumah,"54 i.e.,
  whether it is pure or impure. The pure [terumah] may be eaten by the
  priests and they can benefit from the impure [terumah] by burning
  it.55 If it is oil, it can be kindled [as fuel for a lamp].
  If it is grain or the like, it can be used as fuel for an
  oven.56
54. In the verse, the noun terumah uses a plural form
  alluding to two types of terumah: pure terumah and impure terumah. See
  also Hilchot Ma'aser 6:2.
55. It is forbidden to partake of it.
56. It may not, however, be given to animals as animal
  fodder. See Sefer HaMitzvot (positive commandment 90) which states
  that it is a mitzvah to burn impure terumah. Impure terumah from
  fruits that will not be useful as fuel must be buried.

See this source from Orthodox Union, in the section Explanation of the Procedure in the first item.
Comment: This is inaccurate. There is no Kareit for eating Terumah while impure. Also notably a Temei Met can eat Terumah from the Diaspora.
Comment: @DoubleAA removed reference to *kareis*, very surprised, I thought this was correct. So is the penalty regular *malkos*?
Comment: The punishment is Mitah Bidei Shamayim. But you writing that without a source is no better than me doing so. Don't trust me. Look it up!
Comment: @DoubleAA tried to look around but could not find a direct reference, which is why i asked you here. i always thought it was *kareis* and was wrong, apparently
Comment: @sabbahillel thank you so much for the edit, it is so much better now

Why don't kohanim eat terumah nowadays?


Web App Level Feature not showing in SharePoint 2013

Question: I have a SharePoint 2013 site configured for FBA and Multi Tenancy. In our case, we have a Multi Server Farm, which has a Web Front End, App Server, Search Server, Workflow Server and DB servers. We have custom code to deploy features. We have a web app level feature, which actually creates Custom Diagnostic Areas and Categories. This works fine in our local development environment which is a standalone, but in the multi server farm environment, this feature is not even shown in the Web App Level features. We are not sure, what is going here. Can anyone please suggest, what could be going wrong here.
Answer: Depending on where the Central Administration is hosted (Web Front End or App server), and depending on the target of the  WSP package  (I'm not talking of the scope of the feature; I'm talking about the "Deployment Server Type" setting of the solution), this may happen.
For example, the features contained in the package are only installed on the Web Front End if the "Deployment Server Type" is set to WebFrontEnd. If you browse the CA hosted on the App Server, it thus does not list features that are not physically installed on that server.
Options to solve this include:

Host the CA on the Web Front End as well, and browse it there to activate the feature.
Switch the WSP mode to ApplicationServer (can be done only if it contains only the Web app feature you're mentioning).
Activate the Web app feature from PowerShell, while logged on the Web Front End (and hope the feature event receiver is well-coded, i.e. does not assume the ER is loaded in a Web context!).
Turn the application server to a WFE (by activating the "SharePoint Foundation Web Application" service on it), even if it's not participating in the load-balancing.
Comment: Thanks a lot for your helpful response, Evariste. But I have a WFE and an App Server. Also, I have a Web App Level feature packaged along with other Web level features. This Web App Level feature will create a Custom Diagnostic Area and Category. I tried providing the DeploymentServerType attribute with ApplicationServer and WebFrontEnd(not at the same time, though). But, in either case, the web app level feature is not even getting displayed. I tried activating through PS, but the custom diagnostic area and category didn't get created.
Comment: Finally, we had to turn on the SharePoint Foundation Web Application service on the App Server also. Then we could get it working. Anyway, I am going to mark your reply as answer, since your suggestion was a good pointer. Thank you very much.


May I enter the US on the VWP and then leave and return immediately on a J1?

Question: Is it possible to enter the US on VWP, then leave and return on a J1 visa immediately?
Comment: Why wouldn't it be possible?
Answer: On a thread on Tripadvisor, an almost identical question was asked. In response, user Carmen D mentioned that:

I sent an e-mail to CBP INFO Center.
They told me:
"You are able to enter the U.S. with an ESTA. The burden of proof will be on you to convince the CBP officer your intent while your here in the U.S."
And I asked again and:
"You can visit the US with the visa waiver program. You will be OK with a round trip ticket to show you will leave the US before you start as a postdoc with the J1 visa."

So, it looks like you are fine entering the USA on the VWP, but you will be evaluated as a potential overstay risk just like any other person admitted on the VWP. Make sure you are able to show the immigration official why and how you are going to depart the USA according to the terms of the VWP.
Comment: Can you go to Canada or Mexico or the Caribbean, which would generally not count as leaving otherwise for visa run purposes?


How to set ulimits for a service starting at boot?

Question: I need, for mysql to use large-pages, to set a ulimit - I've done this in limits.conf. However, limits.conf (pam_limits.so), doesn't get read in for init, only for "real" shells.  I solved this before by adding a "ulimit -l" to the initscript start function. I need some sort of repeatable way to do this, now that the boxes are managed with chef, and we don't want to take over a file that's actually owned by the RPM.
Comment: Please have a look to see if you are hitting the same bug.

http://serverfault.com/questions/415570/hugepages-not-utilized-by-mysql-5-0-centos-5/435260#435260
Answer: $ echo "* hard nofile 102400" >> /etc/security/limits.conf
$ echo "* soft nofile 102400" >> /etc/security/limits.conf
$ sysctl -w fs.file-max=102400
$ sysctl -p

The 4 steps can change your system's limits immediately, and can still work after your reboot.
You can change the number "102400" to the number of max open-file in your linux system as you want.
and
$ sysctl -p

to load in sysctl settings from the file specified or /etc/sysctl.conf if none given.
Comment: limits.conf is not read by inittab because limit.so is not read for it. You might be able to hack PAM but I cant figure out which file it might read.
Comment: @Xarses is right. limit.conf will not get applied for some daemon starting at boot time. I don't believe this answers the question.
Comment: Note that the wildcard `*` does not work for `root` user, you'll have to specify `root` explicitly...
Answer: /etc/sysctl.conf should be able to set the ulimits items. I've not been able to test this well but survey says you should be able to stop after it's set in sysctl.conf.
I've found various topics that show it's still a problem though and my team and I have discussed some options around this we have found two potential workarounds.
Option 1:
Most rhel initscripts source /etc/init.d/functions, you could change the ulimit settings there
Option 2:
init claims that /etc/initscript is sourced everytime before init spawns whatever see: http://linux.die.net/man/5/initscript. Interestingly enough they say its where people can set ulimit =)
Answer: My solution was simply doing this in our chef recipe:
# Ensure ulimits are properly set for the initscript
bash "Set Ulimits" do
    user "root"
    code <<-EOH
    echo -e "n#Setting ulimits. Performed by chef recipe MYSQLULIMIT\nulimit -l" >> /etc/sysconfig/init
    EOH
    not_if "grep MYSQLULIMIT /etc/sysconfig/init"
end

This causes the ulimit -l to get set for all initscripts, which may be undesirable in some environments, but is fine for mine.
In a perfect world, I'd get the RPM updated to include a /etc/sysconfig/mysqld, and put the same ulimit -l command in there.
Answer: Self-contained recipe snippet based on this url:
http://pro.benjaminste.in/post/318453669/increase-the-number-of-file-descriptors-on-centos-

Recipe Snippet:
ruby_block "edit /etc/sysctl.conf" do
  _file = "/etc/sysctl.conf"
  _comment = "# TWEAK BY CHEF"
  _content = "fs.file-max = 512000"
  block do
    file = Chef::Util::FileEdit.new(_file)
    file.insert_line_if_no_match(/#{Regexp.escape(_comment)}/, "#{_comment}\n#{_content}")
    file.write_file
  end
  not_if "cat #{_file} | grep '#{_comment}'"
  notifies :run, "execute[sysctl -p]", :immediately
end

execute "sysctl -p" do
  command "sysctl -p"
  returns 255 # which would normally signify error, but doesn't on sysctl on CentOS
  action :nothing
end

ruby_block "edit /etc/security/limits.conf" do
  _file = "/etc/security/limits.conf"
  _comment = "# TWEAK BY CHEF"
  _content = "* - nofile 65535"
  block do
    file = Chef::Util::FileEdit.new(_file)
    file.insert_line_if_no_match(/#{Regexp.escape(_comment)}/, "#{_comment}\n#{_content}")
    file.write_file
  end
  not_if "cat #{_file} | grep '#{_comment}'"
end

Answer: The RedHat way, as described in article 253043 (subscription required) is to add appropriate ulimit statements to /etc/sysconfig/<service name>. For example:
# echo "ulimit -SHn 10240   # nfile" >> /etc/sysconfig/myServiceName

(Use the existing file for your service instead of myServiceName.)
For daemons that start without using the RedHat "sysconfig" script, you would need to add the appropriate ulimit lines to the daemon startup script.
Answer: Not sure of how distro-specific this is, but I have just incorporated a security limit increase by using /etc/security/limits.d/20-somefile.conf in Ubuntu.
Rather than having to modify an existing file, I have an ERB template in my cookbook, set default attributes in an attributes file and then don't have to worry about using ruby blocks with "insert_line_if_no_match" stuff - that seems a little more intricate and the recipe is a bit more readable like this:
execute "activate_sysctl" do
  user "root"
  command "sysctl -p /etc/sysctl.d/10-filemax.conf"
  action :nothing
end

template "/etc/sysctl.d/10-filemax.conf" do
  source "system/filemax.conf"
  action :create
  notifies :run, "execute[activate_sysctl]", :immediately
end

and then this is my template file:
fs.filemax = <%= node[:mycookbook][:system_fs_filemax] %>

Answer: according to man page ulimit is deprecated. You need to use setrlimit. The problem is that is a system call instead of a bash command.
I had this problem with supervisor and this is what I found out.
If the process doesn't have a config file that allows you to make a call to setrlimit() system call. Set it with ulimit on its /etc/init.d bash script. That's the service script that starts your process.
If the process has a config file, like supervisor d then you can use that config file to set the number of files and have the process make the call directly to setrlimits().
Supervisor:
http://supervisord.org/configuration.html#supervisord-section-settings
TomcaT:
http://www.jayway.com/2012/02/11/how-to-really-fix-the-too-many-open-files-problem-for-tomcat-in-ubuntu/
Answer: Try setting that up in /etc/sysctl.conf file
Comment: There are pieces of configuration required to do this that belong in sysctl.conf, and those are in place -- we just need to modify ulimits to allow those hugepages to be accessed.
Answer: I actually wrote a private chef cookbook that is used to set ulimit for us and it works pretty well.  For ubuntu we found the following trick is required if you want a global ulimit setting:
Add the following to your common-session:
session required        pam_limits.so

and in limit.conf you must have the following:
* soft  nofile  64000
* hard  nofile  65000

root  soft  nofile  64000
root  hard  nofile  65000

The root part is important as it seems without that some init script will not work correctly.  So we have a chef cookbook that setup the following and it works great.
Another option we used to use for Tomcat was to deploy Tomcat and then overwrite the init script with a custom which we would set the ulimit for and restart tomcat.  This works great but is a bit more hacky then the first.
I hope this help, and maybe someday I can opensource the cookbook we have internally since its pretty dead simple but might be helpful to others like you.
Comment: This wont solve the poster's issue. Pam is only invoked when a user opens a session (shell). Since the init system is started independently of user sessions, pam does not apply.


Why is History still in Beta?

Question: I know this has been asked previously, but not recently. So, why haven't we moved out of Beta? We are doing well on all fronts except for questions asked and at this point it would be really hard to fix given it is averaging over four years.
Comment: Ah, I'm glad someone asked the question I was wondering about.
Answer: Under current guidelines there are two reasons a "beta" stack might expect to see its status change:

(Good) Its consistently getting more than 10 questions a day.
(Bad) Its not producing consistently helpful content, and its community isn't strong enough to perform the self-moderation function a healthy stack requires.

In the first case, this is what will generally get a site considered for promotion out of beta. We simply aren't there. A quick check shows me we had 8 new questions posted in the last 24 hours, which is a fairly good day for us. Not a barn-burner, but probably better than average. Using my super mod powers, I'm not supposed to give detailed specifics, but I think I can fairly say we've been bumping around above and below the 5-per-day line for years.
In the second case, this is what will get a site closed. Again we have spurts, but I don't think we're anywhere near that level of problem. I'm not empowered with these decisions, but I think we have a very good community here. We mods may slack a bit on occasion on flag handling, but the community seems to be doing a great job of taking care of problematic questions and answers all on its own even when we don't.
So that leaves us in the middle. Despite what the name may lead you to believe, there's no reason why a stack couldn't stay "beta" forever, if that's where it belongs. Sure, that makes "beta" a bit of a misnomer. There's been some talk of changing the name, but that doesn't appear imminent.
Comment: The majority of content-related data is publicly available at SEDE; it's mostly the visitor data which isn't. Here's a dataset for questions asked each day: https://data.stackexchange.com/history/query/509875/questions-asked-per-day-not-closed-deleted, here's a yearly average breakdown: https://data.stackexchange.com/history/query/509888/yearly-average-questions-per-day, and here's a monthly graph: https://data.stackexchange.com/history/query/509890/monthly-average-questions-per-day#graph (the numbers don't quite match Area51 so there must be some data missing, but it's close)
Comment: Is there a way in which users can see a one-year daily average? The only number we see is an average for the whole lifetime.
Comment: I don't believe so. The page I can go to look at it says in a big orange box at the top: "analytics data is intended for moderators only; please don't share the specifics of this data in public", so I have to think this same data isn't publicly available. You could of course try to figure it out yourself going forward by sampling [this page](http://history.stackexchange.com/questions) like I just did, but over an extended period.
Comment: @Benjamin - Oh, but there is the high-level stats on our [Area51 page](http://area51.stackexchange.com/proposals/5169/history)
Comment: Area51's questions/day is a rolling average for the last 14 days.
Comment: T.E.D. I came to this question wondering if the rampant indiscipline in use and abuse of comments was a factor in the site not getting upgraded, but that is apparently not the case.  There is a variety of traffic in comments, to the point of grand arguments like on a discussion forum, that have the meat of a number of new questions and answers, but few users seem motivated to take "hey, that's a question in its own right" and post a question.  Self Inflicted Wound, if one of the objectives is to get out of Beta.
Answer: A rough rule of thumb that I've seen on my sites is that sites with questions in the five figures (>10,000) are "graduated," and the ones still in beta have fewer questions. We're just a bit more than halfway there, and hopefully we'll graduate when we get to (or approach), 10,000.
Comment: As [I was saying on chat](http://chat.stackexchange.com/transcript/message/30389122#30389122), given current stats the situation seems very hopeless, if we're to follow the known rules about graduation from beta.

Why is History still in Beta?


Best equalization for feedback improvement on guitar?

Question: I know guitar feedback naturally comes with high volume while playing in front of speakers, but there are some tips to increase it, such as compression, overdrive, etc.
I'd like to know if there is a particular eq setting to improve (positive) feedback as well.
Comment: Feedback depends on the exact situation, including guitar, amp, effects, temperature, humidity, distance, angle, etc., etc. I would try playing with angle, distance, guitar tone control(s) and maybe a wah pedal. No one can tell you what will help feedback on your rig without playing your rig itself.
Comment: Thank you Todd, I already know that feedback is very singular to location, guitar, amp, and everything affecting the tone "in the moment", but I was wondering if there is some particular frequency equalization that helps positive feedback to came out, if this is physically possible.
Comment: By "particular frequency equalization" it sounds like you're looking for something like "boost 400 Hz". A frequency or frequency range would be completely situational, (which you acknowledge), so we can't give you a frequency or frequency range that will work in general. I can't think of anything at all  that will help in general - except more volume, gain, and compression, which you already know. Am I misunderstanding your question?
Comment: real feedback is where the instrument (strings, body, etc) vibrate or resonate sympathetically with the ambient sound. The looser the strings, the easier they will respond. Sometimes you can tap the guitar (unplugged) and listen to the tone it makes: the closest notes you play to that tone will probably cause the body to resonate and that can make the strings react.
Answer: For feedback (positive feedback) you need plenty of gain.  These sorts of experiments tend to be very setup-dependent, but when I did this I used a regular Ibanez solid body guitar, a Boss CS-2 compressor on full gain, a simple DIY fuzz box also on full, and my simple guitar amplifier (10 inch speaker) on very low volume.  With this I got plenty of feedback in my bedroom, at normal bedroom levels, by sitting close to the speaker.  (The volume was not high enough to damage anyone's hearing at that range either.)
So I would suggest the main thing to do is experiment with lots of gain, and modest volume.
Answer: The way that I get lots of feedback for infinite sustain is to use a compressor with the sustain set as high as it will go.  That usually does the trick, but you can also use a bit of gain on the overdrive pedal to boost the effect.  If you put a wah pedal between the overdrive and the guitar, you can also tune the guitar signal for maximum sustain for your setup.  These techniques can work with even modest volume levels.
I'm not sure what you want the feedback for.  If it's simply for long or infinite sustains, you can also use a granular synthesizer or "freeze" pedal like the Electro Harmonix Super Ego pedal.


What is the best camera to get that will give you a very nice photo on canvas print of 11 x 15 or larger?

Question: I have tried several times to order a canvas print and it always comes back that the picture submitted will not work with the 11 x 15 canvas print and even an 8 X 10 wont work? I have a cannon E ( wont let me print name Santa's E )camera. What is the best type of camera I can buy that I can then make my pictures into Canvas photo's for my house? Just need the name of a good camera and know that it will turn into a wonderful Canvas photo.
Comment: It might be worth saying more about what camera you're currently using, and how you're editing and submitting your current photos for print. I'm surprised they are insufficient for 8x10. It makes me think you're downscaling them somewhere in the process. (That could be a separate question, if you don't want to confuse the issue here.)
Comment: I have no idea what "(wont let me print name Santa's E)" means, but I'm guessing it's an autocorrect error for "Series E". The only camera I know of in Canon's "E-for-entry-level" E Series is the [Powershot E1](http://www.usa.canon.com/cusa/support/consumer/digital_cameras/powershot_e_series/powershot_e1_white#Specifications), a 10 megapixel camera from 2008. In normal use, this produces images of 3648x2736 pixels, which is sufficient for up to 9x12 for anything requiring 300dpi. Canvas printers are often only 150dpi, so you should be okay up to 18x24". I think the problem isn't the camera.
Answer: The key factor to making a good 11 by 15 print is having sufficient resolution.  For 11 by 15, 300ppi (pixels per inch) is ideal.  That means you need at least 3300 x 4500 pixel resolution.  That is a 15 megapixel image.  Any camera that produces decent quality images at 15 megapixels or better (and the correct aspect ratio) should work for producing an 11 by 15 print on whatever media type you choose.  You may need to go higher than 15 megapixels however to make sure that the vertical and horizontal pixel count is high enough, since the sensor may not match the same ratio as 11 by 15.


How to Calculate Gaussian Kernel for a Small Support Size?

Question: How to calculate the values of Gaussian kernel? I think I understand the principle of it weighting the center pixel as the means, and those around it according to the $\sigma$ but what would each value be if we  should manually calculate a $3\times 3$ kernel?
Comment: A 3x3 kernel is only possible for small $\sigma$ ($<1$). In particular, you can use the binomial kernel with coefficients $$1\ 2\ 1\\2\ 4\ 2\\1\ 2\ 1$$ The Gaussian kernel is separable and it is usually better to use that property (1D Gaussian on $x$ then on $y$).
Answer: Gaussian Kernel is made by using the Normal Distribution for weighing the surrounding pixel in the process of Convolution.
Since we're dealing with discrete signals and we are limited to finite length of the Gaussian Kernel usually it is created by discretization of the Normal Distribution and truncation.
I created a project in GitHub - Fast Gaussian Blur.
It uses many methods to approximate the Gaussian Blur Filter and evaluate their speed and quality.
The most classic method as I described above is the FIR Truncated Filter. I implemented it in ApplyGaussianBlur.m in my FastGaussianBlur GitHub Repository.
Regarding small sizes, well a thumb rule is that the radius of the kernel will be at least 3 times the STD of Kernel.
If you chose $ 3 \times 3 $ kernel it means the radius is $ 1 $ which means it makes sense for STD of $ \frac{1}{3} $ and below.
Then just fill your Kernel By:
gaussianBlurRadius  = ceil(stdToRadiusFactor * gaussianKernelStd);
vGaussianKernel = exp(-([-gaussianBlurRadius:gaussianBlurRadius] .^ 2) / (2 * gaussianKernelStd * gaussianKernelStd));
vGaussianKernel = vGaussianKernel / sum(vGaussianKernel);

Comment: how would you calculate the center value and the corner and such on?
Comment: Look at the MATLAB code I linked to. It's all there.
Comment: @asd, Could you please review my answer? If it works for you, please mark it. Otherwise, Let me know what's missing.
Answer: As said by Royi, a Gaussian kernel is usually built using a normal distribution. Each value in the kernel is calculated using the following formula :
$$ f(x,y) = \frac{1}{\sigma^22\pi}e^{-\frac{x^2+y^2}{2\sigma^2}} $$
where x and y are the coordinates of the pixel of the kernel according to the center of the kernel. This approach is mathematically incorrect, but the error is small when $\sigma$ is big. I use this method when $\sigma>1.5$, bellow you underestimate the size of your Gaussian function.
The previous approach is incorrect because the kernel represents the discretization of the normal distribution, thus each pixel should give the integral of the normal distribution in the area covered by the pixel and not just its value in the center of the pixel. If we have square pixels with a size of 1 by 1, the kernel values are given by the following equation :
$$ f(x,y) = \int_{x-0.5}^{x+0.5}\int_{y-0.5}^{y+0.5}\frac{1}{\sigma^22\pi}e^{-\frac{u^2+v^2}{2\sigma^2}} \, \mathrm{d}u \, \mathrm{d}v $$
To compute this value, you can use numerical integration techniques or use the error function as follows:
$$ f(x,y) = \frac{1}{4}\big(erf(\frac{x+0.5}{\sigma\sqrt2})-erf(\frac{x-0.5}{\sigma\sqrt2})\big)\big(erf(\frac{y-0.5}{\sigma\sqrt2})-erf(\frac{y-0.5}{\sigma\sqrt2})\big) $$
Finally, the size of the kernel should be adapted to the value of $\sigma$. My rule of thumb is to use $5\sigma$ and be sure to have an odd size.
Comment: First, this is a good answer. I +1 it. In discretization there isn't right or wrong, there is only how close you want to approximate. I agree your method will be more accurate. But there are even more accurate methods than both. In many cases the method above is good enough and in practice this is what's being used. Welcome to DSP!


How do I make my phone number appear in my friends' phones?

Question: I updated my number on Google+, but that's not displayed in my friends' phone or their Google Contacts. It appears when they see my Google+ profile, though.
Answer: Other users' address books are not synced with your G+ profile AFAIK.  Your friends would have to either manually update their Google account contacts on the web or manually update their address book on their phone.  Either way, if sync is turned on for that account on a friend's phone, updating the one will update the other.
Answer: Your numbers are not synced to Google Contacts. Your friends need to install the official Google+ app in order to see your numbers.


Rails include module in model trouble

Question: I have module in /lib/models/scopes.rb
module Models
    module Scopes
        extend ActiveSupport::Concern
        ...
    end
end

I'm trying to include it from model:
class User < ActiveRecord::Base
  include Models::Scopes
end

And getting error:

NameError: uninitialized constant User::Models

How to solve this trouble? Maybe it`s wrong to keep this types of files in /lib?
Environment:
Rails v3.1
Ruby v1.9.3
Answer: Rails doesn't require files in the lib directory automatically, but you can add to the autoloaded paths in config/application.rb:
config.autoload_paths += %W(#{config.root}/lib)

Restart the server to pick up the new settings.
This will now load the file automatically when the module name is first used. In development mode, you might want to reload the module after every change in order to see the changes without restarting the server. To do that, add it as an eager load path instead:
config.eager_load_paths += %W(#{config.root}/lib)

The scope shouldn't be a problem as long as you don't have a Models class or module within User or anywhere else.
Answer: when you define your class, you're "opening" a new scope. So when you do Models::Scopes, ruby is looking for User::Models::Scopes. You can fix this by using ::Models::Scopes, the :: telling ruby to look in the global scope.
FYI: I'm not sure about the terms I used or even if my train of thought if correct; but the solution should be good anyway. I'd think Ruby would try for ::Models::Scope after failing to find User::Models::Scope, but it doesn't.. Maybe there is a User::Models scope defined somewhere? Anyway, as you can see, I'm not yet familiar with those. You might want to dig on the subject if that interests you
Comment: then you should refer to @SMWEB answer. I skipped the part where your is in `/lib`. You first code should have worked fine if your file was loaded.
Comment: Thank you for answer. But now, with ::Models:Scopes, Rails throw "NameError: uninitialized constant Models"

Rails include module in model trouble


What is the significance of enthalpy definition not under constant pressure?

Question: Under constant pressure (and only PV work), change in enthalpy can be shown to equal change in heat. If enthalpy is not meaningful outside of constant pressure, then why not use heat instead? So I think it must be meaningful outside of constant pressure scenarios, but I couldn't figure it out myself. Can someone help?
Comment: Do you know abt internal energy?
Answer: There are many processes that take place at constant pressure, such as the change of phase from a liquid to a vapor for a pure substance at constant temperature.  Also, the heats of chemical reactions and heats of formation of compounds are typically cataloged at constant temperature and pressure.  So the enthalpy comes into play in both these instances.
The first law of thermodynamics for a closed system is expressed conveniently in terms of the change in internal energy of the system.  However, for an open system (in which mass is flowing in and out) operating at steady state, the first law is more conveniently expressed in terms of the enthalpy, not the internal energy.  And, of course, all industrial applications of thermodynamics involving continuous processes are operating at steady state.
Chet


How to automatically crop text messages when SMS character limit is reached?

Question: Is there a way to prevent the Messages app from sending long texts? It's generally a nice feature, but my current plan has free SMS which I cannot use when overstepping the character limit - instead, the "long text" will be sent as an MMS and charged as such.
Answer: The default Messaging app does not show how much characters you have typed/left for it to be sent as an SMS. So you can use a third party messaging app like Textra SMS.
When you start typing the message, after typing a minimum of 22 characters, you will see a counter showing you the number of character left for it to be sent as a single message(eg. 130/1 - Which means 130 character are left).
The total length of the a single SMS message is 160 in Textra app(which is mostly the normal limit of a single text message). Based on your limitation you can send multiple separate text message to avoid sending a single MMS based on the counter. I don't send lengthy text messages but AFAIK even if your type more than 160 characters it will still be sent as an SMS rather than an MMS. But it would cost you twice the amount for that 160+ charactered SMS message.


Cheapest Metro/RER ticket in Paris

Question: I will be staying 10 days in Paris with a day visit into Zone 5.  What is the best public transport ticket: Navigo Decouverte OR Origin/Destination OR T+  ?
Comment: I chose Navigo Decouverte in 2015 for a week stay with a trip to Le Bourget. Keep in mind that Navigo Decouverte is valid for a given week (from Monday to Sunday). You can ask for an extension ticket to your destination/Paris (_complement de parcours_)
Answer: If you only have one journey into zone 5, the cheaper alternative is to buy a Origine-Destination ticket for that journey.
To decide wether for the everyday travels you are better buying T+ tickets or a Paris Visite depends on how many different travels you expect to do daily and how they are done (see http://www.ratp.fr/en/ratp/r_61656/t-ticket/ for the rules that apply for connections with T+). Keep in mind that T+ is only valid for zone 1-2.
If you buy T+ tickets by 10, if you expect to use more than 25 tickets on 5 days, you're cheaper buying a zone 1-3 5 days Paris Visite.

Cheapest Metro/RER ticket in Paris


Are road cranks less strudy than comparatevely priced MTB cranks?

Question: Road bikes are built to face different challenges than MTBs. Does this lead to difference in the crank strenght versus weight optimization? Will road cranks tackle to the occasional bump onto a stone on the trail?
Comment: Aside from exotic units I doubt that there's any significant difference.  The main differences would be in shaft length, shaft offset, body length, etc.
Comment: There might be issues with compatibility. If you look at things like Hollowtech, road cranks are usually made for 68mm, while mountain bike are often 73 mm. This doesn't matter for square taper and octolink, because this is all handled by the bottom bracket, but with hollowtech, the drive has part of the axle built into the drive side crank, so road cranks may not work with your mountain bike. Also, there might be issues if you are using road chainrings as well, as they are larger and might interfere with the chainstays, which is usually splayed out further to accommodate larger tires.
Answer: In general, road cranks are lighter because they use less material than mtb cranks. Mtb cranks use more material so they can handle more abuse. Compatibility aside, I would be cautious in using road cranks for much more than cyclocross duty. You may never have a problem, but do you really want to find out the hard way?