Do particles also have intrinsic linear momentum (linear analogue of spin)?

Question: We know from quantum mechanics that microscopic particles have spin, which is a kind of intrinsic angular momentum. The particle has angular momentum without physically rotating.  In a similar way, do particles also have intrinsic linear momentum? That is, can the particle have linear momentum without physically moving? If not, then why not?
Comment: The equivalent of intrinsic spin for linear momentum is the mass, which is $P^2 \vert a \rangle = m^2 \vert a \rangle$
Comment: If OP means the 3-momentum, then no. There is no frame where an electron has zero spin, but an electron has no 3-momentum in its rest frame.
Answer:
Do particles also have intrinsic linear momentum (linear analogue of spin)?

Some do. A photon moves linearly at c, and its momentum is p=hf/c. The linear momentum is an aspect of energy-momentum, which is denoted by the Poynting vector as per this Blaze labs picture:

In addition neutrinos travel at a speed which is so close to c that we can't tell the difference. And the neutrino "was first hypothesized by Wolfgang Pauli in 1930, to account for missing momentum and missing energy in beta decay".

We know from quantum mechanics that microscopic particles have spin, which is a kind of intrinsic angular momentum. The particle has angular momentum without physically rotating.

You need to be cautious here, because the Einstein-de Haas effect demonstrates that "spin angular momentum is indeed of the same nature as the angular momentum of rotating bodies as conceived in classical mechanics". And because the Wikipedia electron magnetic moment article says this: "From classical electrodynamics, a rotating electrically charged body creates a magnetic dipole with magnetic poles of equal magnitude but opposite polarity. This analogy holds as an electron indeed behaves like a tiny bar magnet". A bar magnet has a magnetic field like a solenoid, and you can simplify a solenoid to a current loop. In addition check out the static-fields section of the Wikipedia Poynting Vector article:

Note where it says this: "While the circulating energy flow may seem nonsensical or paradoxical, it is necessary to maintain conservation of momentum". IMHO you need to think in terms of a tornado. It has an intrinsic spin, and this makes it what it is. The air is rotating, but the tornado itself isn't. If you could somehow stop the rotation, it wouldn't be a tornado any more, it would be just be wind.

In a similar way, do particles also have intrinsic linear momentum? That is, can the particle have linear momentum without physically moving?

No. A particle such as an electron can have an intrinsic angular momentum without physically moving.

If not, then why not?

Because when it has linear momentum it's moving linearly. However what Slereah said is kind of right: "the equivalent of intrinsic spin for linear momentum is the mass". You can understand this by thinking of the photon in the mirror-box. See http://arxiv.org/abs/1508.06478 (the 't Hooft is not the Nobel 't Hooft). When you catch a massless photon in the box, it increases the mass of the system. The photon is still going round and round at c, but it's effectively at rest, so the momentum is now exhibited as mass. Photon momentum is resistance to change-in-motion for a wave propagating linearly at c. When the wave is going round and round at c, we call its resistance to change-in-motion mass. This is what underlies E=mc². When you open the box, it's a radiating body which loses mass. In a way mass is just the flip side of energy-momentum.


speed control of induction motor using dimmer

Question: i want to control the speed of induction motor single phase (about 1.5 kw /  2 hp  \ 220 volt \ 50 hz and 1400rpm) using dimmer(triac) , i try this circuit
i chang the value of C1 to get best control
the circuit worked acceptably but not very well , not requested
i Noticed that the range of control the speed with variable resistance R1
is tight and when i Reduce the Speed  the motor have some noise
1-how i can solve the proplem of the thigt range of the control speed?
2-how i can solve the proplem of the noise in the motor?
3- what the Disadvantages and Damage of this kind of control on the motor?
and by this kind of control As a result i reduce the voltage so the torque will be reduce , are i am right ? so what is the benefits?
for circuit Rs= 27 Ω ,5 watt and c1 = 300nf ,400volt and the load  is the motor ant triac is bta41
Comment: and i noticed there is Amount of heat in the motor
Comment: Is this a [wound-rotor motor](https://en.wikipedia.org/wiki/Wound_rotor_motor) where you have connections to the rotor via slip-rings, or a [squirrel cage rotor](https://en.wikipedia.org/wiki/Squirrel-cage_rotor) motor where there are no connections to the rotor?
Answer:
speed control of induction motor using dimmer

Induction motor speed control is done by varying the frequency of the applied voltage. Raising or lowering the voltage can have some speed control effects but these will be small, difficult to control, load-dependent, possibly cause the motor to overheat and, are not generally recommended.
This applies to three phase induction motors and single phase induction motors using a start/run capacitor.
People use VFDs to control induction motor speed but even these are not particularly helpful (a generalism of course) with single phase induction motors that use a capacitor.
Comment: but I have SINGLE PHASE induction motor and VDFs only control three phase motor
Comment: you mean the dimmer is not effective
Comment: Yes. This means the dimmer can never be very effective. It has limited use with motors that have designs suited to that. Also the load must be suitable. It works best with fans and centrifugal pumps.
Answer: The reason this didn't work well by the way is that in an induction motor, torque is a factor of the ratio between voltage and frequency, and a squirrel cage motor is designed for a particular ratio. So by using a dimmer, you are not changing the frequency, only the voltage and thereby affecting that ratio. Motor torque varies by the square of the applied voltage at a fixed frequency, so if you give that motor 50% voltage, it will only develop 25% of it's rated torque. That then means slip increases, the motor draws more current in an attempt to return to normal slip speed, but it can't, so the extra current just creates heat needlessly, until eventually the motor burns up.
A VFD works because it DOES change the voltage AND FREQUENCY together, maintaining the V/Hz ratio that the motor is expecting, so it delivers rated torque at any speed.
There are VFDs designed to be used with single phase motors, but not ALL single phase motors. Unlike 3 phase induction motors which are all built basically the same, there are numerous methods of making single phase induction motors function. This is because with single phase, there is no rotating magnetic field generated to make the motor begin spinning, it just cycles back and forth. Once a motor STARTS spinning however, it keeps spinning. So single phase motors must be designed with some "trick" to get that spin started, usually in the form of a temporary phase shift. Motors that use a separate winding (Split Phase) or a capacitor (Cap Start) to create that phase shift, but then use a centrifugal switch to remove it once the motor is spinning, cannot be used with any form of speed control because slowing them sown re-engages the starting method and it was not designed to be in the circuit continuously. There are however two forms of single phase induction motor that can be used with speed control, a Permanent Split capacitor (because the caps ARE designed to be in the circuit the entire time) and a Shaded Pole motor. Shaded pole motors are particulary well suited for simple voltage control via "dimmer" because the torque is poor anyway, so they are generally only used in applications that don't need a lot of torque, like small fans. PSC motors can also be used with dimmers but the torque issue is still there so it is very load dependent.
Bottom line, if yours is an induction motor but not Shaded Pole or PSC, you cannot use any form of speed control on it.
Comment: How common are induction motors that are not PSC? I've never come across them - in my experience (air movement, machinery, etc) they are all PSC. There are PSC motors that have an extra capacitor for starting that is disconnected via a centrifugal switch - perhaps that is what you are talking about?
Answer: Except for small fan motors, single-phase motors are generally not suitable for speed control. Universal motors are DC-type motors with commutators that can be used for either AC or DC. They are suitable for simple dimmer-control type speed control.
The best and usually the only alternative for an AC motor is to buy a motor that is suitable for variable speed and a matching controller. There are VFDs rated up to a few horsepower that convert single-phase input power to three-phase output. Also available are commutator-type DC motors with either field windings or permanent-magnet fields. DC motors controllers, similar to dimmers, are available for both types. Brushless DC motors are also available. They use another type of controller.


How to say Alpha Male and Alpha Female in Spanish?

Question: How does one say

Alpha Male (dominant, macho man)
Alpha Female (dominant, femenina woman)

in Spanish?
Answer: We do use the expression "macho alfa" in Spanish (the greek letter alpha translates to alfa in Spanish.)
I haven't heard much, if at all, the expression "hembra alfa" but that would be the translation, and we can see in the ngram viewer that it's somewhat used.

Other alternative would be to use "dominante" instead of "alfa", although there we tend to use "hombre" and "mujer" instead of "macho" and "hembra".
The ngram graph for "hombre dominante" and "mujer dominante" is priceless.


How can I align the model to the axes?

Question: I have a model that I initially started to create not exactly along the axes. I need to rotate it so that the faces go exactly along the axes.
And you also need to find out the angle of rotation of the model relative to the position when it will look exactly along the axes.
Is it possible to do this ? I twisted the model in every possible way, but nothing brought results.
Comment: First thing, you are in Global orientation mode, so maybe the local orientation is correct, what does it give if you press Alt R in Object mode?
Comment: Or if you switch to _Object Mode_ instead of _Edit Mode_, what are the values for _Rotation_ in the sidepanel on the top right? It would have been good if you showed a screenshot in _Object Mode_, too.
Comment: hehe, this Q&A is really a testament to how far removed from a CAD software Blender is :)
Answer:
In Edit Mode, select an element aligned to your desired axes, and Header > Transform Orientations > Create a Transform Orientation from the element, by clicking the little '+' in the pop-up.
In Object Mode, set the Header > Options to affect only 'Origins'
With the object selected, Header > Transform > Align to Transform Orientation.

Now the axes will be aligned to the selected element. Uncheck the 'Origins' option.

Before straightening the object, (AltR) you will be able to read the old rotation from the N panel > Item > Transform > Rotation fields. (Perhaps stash that rotation on a copy)
Answer: I assume that in object mode the model has a straight orientation, so you have to rotate it to align straight lines with the 3D world.
There are many ways you can choose to perform the task, I would use bones.
Go to edit mode, select a vertex belonging to a straight line, press Shift S > Cursor to selected.
Back in object mode press Shift A > Add Armature > Single bone.
In the Armature Edit mode, turn on vertex snapping and snap the tail of the bone to another vertex of the straight line.
With the bone selected in its edit mode, press E, Y, move the mouse, Enter, to extrude a new bone aligned with the Y world axis.
Set the roll of both bones to 0.

Back in Object mode, select the model, Shift select the armature, go to pose mode, select the oblique bone and press Ctrl P > Bone, to parent the mesh to the rotated bone.
Set the rotation mode of the bones to "Euler XYZ".
Select the straight, bone, Shift select the rotated bone, press Shift Ctrl C > Add Copy Rotation bone constraint.
In the bone constraints panel Apply the copy rot constraints.
Back in object mode, select the mesh and press Alt P > Keep transform, then delete the armature object.
In the "N" properties panel you can read the exact value of the rotations involved in the process (in my example 0,0,7.47059 degrees).
If you press then Ctrl A > Apply all transform, you will end up with an aligned model with all its transform values resetted (000, 000, 111).
Answer: Presuming that the object's rotation is applied so that Clear Rotation with Alt+R doesn't work, there are probably smart ways to find out the angle of rotation your object is off the axes - but I forgot them (but while I was preparing my answer I saw that @joshsanfelici already provided a good one).
Another way you could get the angle is the following (this method is in case your plane is just rotated on the Z axis and flat in XY): in Edit Mode, select some of those edges of which you want to know the angle.

While still using Global orientation, press E Z to extrude them (up or down doesn't matter) constrained to the Z axis.

Add a new object, preferably one with rectangular sides like a cube. Make sure the Snapping options are set to Face Project and Align Rotation to Target.

Select the cube. Since you only need the Z rotation, lock X and Y rotation in the sidepanel to avoid weird rotations of the cube. Press G to move it towards the extruded faces. With either the Snap tool enabled (the magnet symbol left to the Snapping options) or holding Ctrl for temporary snapping make sure the cube snaps to the new faces.

After confirming the new position of the cube with left-click, the Z rotation of the cube shows the angle to which your mesh is rotated off the global axes.
In my case it showed -16.4° but of course there can be decimal places that might just be shown rounded. The best is to copy the value from the input field to get the exact angle.

Now select your mesh, go to Edit Mode, select all with A, then press R Z to constrain rotation to the Z axis, paste the angle with Ctrl+V followed by minus to reverse whatever value it was and hit Enter. Now your mesh is aligned to the global axes.
Answer: If you can apply object's transforms, You could go to edit mode, select some mesh elements that have normals in the orientation you would like to match the axis, make Custom Transform Orientation out of them, go to object mode and run C.object.matrix_world = C.scene.transform_orientation_slots[0].custom_orientation.matrix.to_4x4().inverted() in Python Console.

How can I align the model to the axes?


Is it possible to reduce without boiling?

Question: I would like to concentrate flavour by reducing the water content but I do not wish to alter the temperature of the liquid.  Is there a way to reduce the water content without boiling?  Apart from waiting days for evaporation?
Comment: Can you be more specific about what it is you're trying to reduce and why you're worried about temperature changes?
Comment: Boiling? Can we simmer?
Comment: `I do not wish to alter the temperature of the liquid`... just leaving it out will cause it to move toward the ambient temperature of the room. Are really wanting to 'not alter' or just 'not boil'?
Comment: You say that you "*do not wish to alter the temperature of the liquid*", but both the title and the actual question talk about boiling. Is freezing out of the question too?
Comment: I am making cold drip coffee.  I was trying to concentrate the liquid but find that altering the temperature too high or too low is changing the flavour.  I'm experimenting ...
Answer: It's not necessarily a practical home kitchen answer, but rotary evaporators do this, by lowering the pressure over the liquid and circulating the liquid to increase surface area.
There does exist a culinary vacuum rotary evaporator, for only $9,999.95 by special order! Note that it also captures the vapor to condense, because often the flavor you want is actually volatile aromatic compounds, which evaporate faster than the water does, so trying to evaporate/boil away water is futile.
So if what you want to concentrate is aromatic, you're probably out of luck for home purposes. If you just want something non-aromatic dissolved in the water (dumb example: reducing sugar water into syrup) then boiling/evaporation can work, though. You could certainly speed things along by using as broad a surface as possible (a large pan), gently heating, and blowing a fan over the surface. But it's still going to take an awfully long time without actually boiling.
Answer: You could put the container of food into a bigger closed container also containing a strong desiccant like zeolithe or silica gel - these will probably needed to be dried in a hot oven before use, but that has nothing to do with heating or not heating the food. Make sure the desiccant is kept from contacting the food directly. The desiccant will constantly strive to dry the air in the container, whilst the food will try to do the opposite and thus lose moisture...
Comment: that's an interesting idea! Do you have any estimation for the time saved by this process vs leaving the stuff in a standard room atmosphere?
Comment: No... but since this is a  commonly advised method in chemistry  texts, that is probably where to look for estimates...
Comment: Ah, I was hoping for an entertaining anecdote of homegrown kitchen science.
Comment: There are some dishwashers on the market that use zeolite to dry the dishes, so use near food-contacting items to draw away water is not unheard of...
Answer: There are no practical ways to do it quickly and without heating.
If you want to go with room temperature dehydration, agitation will help. There are products meant to stir food for you (I used to have a nice one by some British startup, it ran off 4 AA batteries), or you could use a stand mixer. When you use a very slow setting, the temperature rise through friction will be negligible.
Combine that with a large surface and a chamber of very dry air as suggested by rackandboneman for even quicker evaporation. This should shorten the process significantly. But it will still be a "set it up and come after a long time" thing, not a "cook it up quickly" thing. And you'll probably be within the danger zone for any usable amount of food, so you should only use it with shelf stable liquids, unless you can afford to set a refrigerator aside for the process.


Using Python with a flexible remote library that resides in a different git repo?

Question: I work on a project that uses a lot of different git repos. Some are open source and some are closed source. Often times there is python code written that would be useful for both open and closed source sides of the project but it is not easy to share between the two.
I am wondering if anyone has a slick general way to solve this problem with out the obvious answer of "install your library on every system you want to run the scripts on" There are a few reasons why that is not a viable answer for us.
We have kicked around a few ideas. The simplest would be to have an open source library repo that we require people to sync before running scripts in either repo that utilizes it. While this works it is quite manual and could lead to issues like people having out of date versions or forgetting to sync the library themselves.
The other way I could see doing something like this would be to distribute a dummy python file that handles all the syncing and captures imports as they happen.
For example if I ran:
import favorite_lib
It would import the dummy favorite_lib.py I have in each repo that needs access to favorite lib that would then in turn git clone or git fetch the favorite_lib repo in the directory where the script lives.
With that in mind I would also like to do something like:
from favorite_lib import commands
favorite_lib would be sync'd and the commands.py file from the directory would be imported.
I haven't tried implementing the above but I believe it is mostly possible.
Am I missing some precedence for this use case? Does anyone else have a better idea? I have searched around and asked a number of people with no real concrete answer.
Answer: Submodules
Comment: This is definitely an interesting idea. It still isn't quite as automatic as I would like, people running scripts would have to be aware of the mechanics of submodules and need to update the libraries accordingly. I could make wrapper scripts that handle that in the actual submodule itself though. Still wondering if there is something more automatic out there. Thanks for the reply.
Comment: Yes, those are valid points. However, submodules also guarantee which revision of the submodule is being used. That way you can guarantee consistency across many teams and team members.


Replacing Eidolons

Question: My character recently got in a fight with her Eidolon and now she refuses to obey orders so i wanted to ask. Is it possible to replace an Eidolon with another Eidolon?
Comment: Over what were the two of you fighting?
Comment: My Eidolon was engaged in a duel against another person and she won but the party needed information from the guy so i ordered her to stop  which she did not take kindly.
Answer: Completely replacing an Eidolon is, according to the Advanced Player's Guide, Ultimate Magic and Ultimate Campaign, not possible. However, an Eidolon is inherently loyal to their summoner. While it will not obey commands that will hurt it just because or are otherwise spiteful, it will obey regular commands, even those who would otherwise hurt it when it would achieve a goal. So the best way to solve this issue is (just like in real life) not with violence or by avoiding the issue, but talking over your differences and settle them that way. Also, make sure that your DM knows that this is how Eidolons function.

Replacing Eidolons


No train reservation

Question: Applying for a French visa. My itinerary is Abuja- London- Paris - Amsterdam- Abuja. I plan to fly from London to Paris but take the train from Paris to Amsterdam. So I booked the flight for all except for that leg, I mentioned this is my cover letter detailing my plans for the whole trip. I dont want to buy a refundable train ticket like some people do. Is it better to just include that leg of the trip in my flight booking for the purpose of the Visa application and revert to my plan if Visa is approved or does mentioning that I plan to buy train ticket for that leg suffice.
Comment: I don't think they will care for a minute about an intra-Schengen train ride. What they are a lot more concerned about is about the applicant leaving the Schengen Area.
Comment: I do not have an exact answer to the question, but I gues "it will depend" - having a ticket will probably be on the safe side. I don't see much difference in getting a refundable flight ticket vs. a refundable train ticket, though. By the way: Unless you have specific reason to fly, the train between London and Paris is faster and more convenient.
Comment: Just curious as to why the London transit is planned rather than direct to Paris?
Comment: I'm planning to spend 2 days in London
Answer: There are many ways to travel from Paris to Amsterdam and for many of those you do not need to buy tickets in advance.
Visa officials know and do understand that.
If you prefer to show a ticket/reservation, look into bus travel. If booked early they can cost as little as €15.
Answer: You can write a note that you're going to take the train to cross from Netherlands to France and submit it along with the rest of documentation, so they're confident that you did think of that.
I was adviced to do just that at visa center and did, with success.

No train reservation


Does the US constitution have a clause/procedure for defaulting?

Question: Current US debt stands at 20+ trillion. Is there there a clause or rules/procedures on defaulting in the US constitution? If so, how are the distribution of assets and liabilities handled?
Comment: Based on previous debt ceiling posturing, no rules/procedures. Whatever Executive wing decides, goes. I have never seen any proposed course of action that was publicly rejected as "against existing rules".
Comment: Would the 14th Amendment (Section 4) be enough to prevent a legal default?
Comment: https://politics.stackexchange.com/questions/2250/what-exactly-are-the-formal-rules-around-us-paying-off-debt?rq=1 is close, if not an actual duplicate.
Answer: The only relevant parts in the constitution itself would the section 4 of the 14th amendment.

The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned. But neither the United States nor any state shall assume or pay any debt or obligation incurred in aid of insurrection or rebellion against the United States, or any claim for the loss or emancipation of any slave; but all such debts, obligations and claims shall be held illegal and void.

What it actually means hasn't been litigated since the US has never really "defaulted" despite political posturing over the debt ceiling before.
Due to the mechanics of sovereign debt, there is no real danger of "default" for the US (outside of a politically generated debt crisis).  The danger from extremely high debt would be unacceptably high levels of inflation.  Hearing about "default" in a case like Greece is because Greece does not issue their own currency and control their own monetary policy.  The USD on the other hand is the reserve currency of the world and gives the US lots of advantages because of how much trust is placed in it.
Comment: @Noah - The Romans' political system(s) handled finance very differently from the current American system. It's a stretch to criticize this answer based on an entirely different system.
Comment: Debt and war were the main contributors of the fall of the Romans. I wouldn't say "no real danger of default." There's always the possibility.
Comment: @Noah Please outline for me the process by which the Federal Reserve runs out of United States Dollars to buy the various forms of securities issued by the Department of the Treasury.  If you cannot, then please define what you mean by default, because anything along the lines of "not having enough dollars" is literally impossible so long as the Federal Reserve exists.  I already pointed out that inflation can be bad; hyperinflation can even cause governments to fall.  None of that has anything to do with a "default" when central banks and fiat money is involved.


How can I deploy custom config files to an Identity Server container?

Question: We'd like to enable the Sitecore Federated Authentication on Sitecore 10.2 with containers. I've updated the ClientId, TenantId, claim transfermations, etc... in different xml files. But I don't know how to deploy those files into the Identity Server container.
Answer: You would need to build a custom Sitecore image for the Identity Server: https://doc.sitecore.com/xp/en/developers/102/developer-tools/building-custom-sitecore-images.html
You need a project with your custom files that you can build in your solution Dockerfile (with msbuild) just like the platform build which is probably already there.
Then you need to change the Dockerfile for the ID to copy the files from that artifact (and change the docker-compose-override to pass the necessary arguments). This ID Dockerfile could be something like:
# escape=`

ARG PARENT_IMAGE
ARG SOLUTION_IMAGE

FROM ${SOLUTION_IMAGE} as solution
FROM ${PARENT_IMAGE}
SHELL ["powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';"]
WORKDIR C:\Identity
# Copy identity artifacts
COPY --from=solution /artifacts/identity/ ./
ENTRYPOINT ["dotnet", "Sitecore.IdentityServer.Host.dll"]

Comment: Thanks for the information. But I only got 2 xml files to deploy. Do I still need to create a project and execute the build? Can I just "copy" those 2 files while the IS container starts?
Comment: No, you should really do this the right way. It's really not that much work. You can copy those files but that is just crappy and not maintainable.
Comment: thanks for that. Much appreciated!


How to use HKDF to combine two keys

Question: I have heard that to combine two keys HKDF is better than using XOR function. But if you look at the HKDF RFC I could not figure out how to use it for concatenating two keys. What I can see is HKDF can be used to derive a key from another key. So I want to know how to use HKDF to concatenate two keys.
Answer: If you have two keys of constant length, using HKDF is rather pointless.
You can simply combine them using a hash function like SHA-2:
$$combined\_key = \text{SHA-2}(k_1 || k_2)$$
Comment: @user10988 Hashing is better than xor-ing, for the same reason that HKDF is better than xor-ing. HKDF with a constant salt is a hash.
Comment: In CSE I have seen HKDF is recommended to use for key concatenation because it preserves the entropy unlike in a XOR function. http://crypto.stackexchange.com/questions/11405/how-to-calculate-entropy-of-a-combined-key?rq=1. So why you are saying HKDF is pointless. Please enlighten me. I want the finale key to be as random as possible. Thats why I am using HKDF to concatenation without using HASH alto or a XOR function.
Comment: @user10988 In your scenario HKDF basically comes down to a HMAC-SHA-256 call. HMAC has no advantage compared to SHA in this scenario, because the input is of constant length, so you might as well hash.
Comment: Thank you for explanation. One more question.Will using a hash function be better than use XOR the two keys(Considering the entropy)?
Answer: Forgive me for sounding condescending – that's not the intent – but to "concatenate 2 keys" you use "concatenation" operation. Not XOR, HKDF, HASH/SHA-2, etc. The only proper way of concatenating an n-bit Key1 and m-bit Key2 - without entropy loss - is to concatenate them.

How to use HKDF to combine two keys


Sample size for binomial distribution for rare events

Question: I would like to estimate the parameter p in a binomial process but need to determine the sample size required. I believe the event is fairly rare, and I have read the normal approximation may not be appropriate for rare events. What would be the best way to determine the required sample size to estimate p for rare events?
Comment: Just how low do you expect $p$ to be, and what precision do you need in the estimate?
Comment: I'll be sampling from a few different groups. I'd estimate p at about 2-10%, depending on the demographic i'm sampling from. I'm looking for a precision of 1%.
Comment: Do you want to be able to distinguish the values of $p$ among the groups? If so, how many groups? Is all that you care about the value of $p$ within each group, or are you also trying to correct for covariates (age, sex, socioeconomic status,...), perhaps trying to model $p$ as a function of several variables?
Answer: When you're down in the few percent range of rare events you might think in terms of a Poisson distribution, which has a very useful property: the variance of a Poisson rate equals its mean. If you have specified failure rates that you would like to distinguish, Gerald van Belle uses this property to propose a simple rule of thumb (page 40):

Suppose the means of samples from two Poisson populations are to be compared in a two-sample test. Let $\theta_0$ and $\theta_1$ be the means of the two populations. Then the required number of observations per sample is:
$$n=\frac{4}{\left(\sqrt{\theta_0}-\sqrt{\theta_1}\right)^2}.$$

That provides 80% power to detect the difference at a significance level of p < 0.05. So say that you expected one transcriber to make 4 errors per 1000 words and another to make 9 errors per thousand words. You would need to evaluate $\frac{4}{(3-2)^2}*1000= 4000$ words from each transcriber to distinguish them, under those specifications.
Why power calculations use normal approximations
I checked this rule-of-thumb estimate for 4 versus 9 errors per 1000 words against the formal binomial sample-size estimates provided by the bsamsize function in the R Hmisc package, the allegedly "exact" test of inequality of proportions between two independent groups provided by the G*Power program, and Russ Lenth's Java applet (without the continuity correction). They estimated 4054, 4054 and 4055 per transcriber respectively, pretty close to the rule of thumb.
Then I looked at the details. All of these power-calculation tools use the normal approximation! G*Power, even when you select the "exact" option, forces use of the normal approximation for sample-size estimation and only does exact calculations for other options. If you force G*Power to do an exact calculation (with its otherwise useless "achieved power" option) for 4054 words and the above error rates, you find a very close result to the desired type-I-error-rate/power targets: p = 0.052, power = 0.813, by likelihood-ratio test.
Another way to express the Poisson rule of thumb shows why power calculations (unlike single-sample confidence intervals, for which the binom package in R provides 11 different methods) routinely use normal approximations.
Consider how many counts you can distinguish between two conditions with n=1, just one experiment for each condition. In the above example with 4000 words, we have power to distinguish 16 errors from 36 errors, not quite a two-fold difference. In general, that above formula provides power to distinguish $k^2$ errors from $(k+2)^2$ errors, $k=4$ in this case. The next example with integer $k=5$ would finally provide power to find a two-fold difference, 25 versus 49 expected errors.
Then, recall that the normal approximation works pretty well if the total number of counts is greater than 5 or 10. This answer illustrates, and provides Python code for further exploration. But if you want to be able to detect differences in proportions on the order of two-fold or less, we just saw that you need to have 25 or more counts in the less frequent condition. When you have enough power to detect a two-fold difference, you are already in the range where the normal approximation to the binomial is OK.
In this particular practical situation, uncertainties from differences among speakers and among those doing the transcriptions among the vendors being evaluated should greatly outweigh any very minor distinction between normal-approximation and exact power calculations.
Comment: Thank you! How might I modify that rule of thumb for a higher level of power than 80%? I found a binomial sample size estimator implemented in R (binomSamSize) and used the Fosgate estimation approach. The actual Fosgate paper (Fosgate 2005) mentions that it is a less conservative approach than the Clopper–Pearson estimation approach. Are you aware of a Clopper–Pearson approach to estimating sample size in R?
Comment: @user6883405 if you look at the (freely available) chapter by van Belle linked in the answer, you will see that the numerator of 4 in that rule of thumb comes from dividing a more generic numerator of 16 (for 2-sample comparisons) in Table 2.1 by a factor of 4. For 90% power, use instead a numerator of 21/4 or 5.25; for 95% power, use 26/4 = 6.5; for 97.5% power, 31/4 = 7.75, based on values in Table 2.1. More on other approaches when I get a chance later.
Comment: @user6883405 elaborated more on why the normal approximation is OK for most practical power calculations.


Newey West estimator, application

Question: What is the application of the Newey-West estimator of variance in case that we have the presence of autocorrelation in our model?
Answer: You run a linear regression, but suspect that the errors may have heteroscedasticity and/or autocorrelation in them. This can mess up your parameter covariance matrix, which means that your inference tests are all under question. For instance, t-statistics of parameter coefficients are quetsionable. Luckily, the coefficients themselves are probably fine. So, you want to adjust your parameter covariance matrix.
You could use heteroscedasticity and autocorrelation consistent (HAC) estimators to do it. Neweay West is one of these tools. You run it and get a new parameter covariance, which you can use for the inference, including parameter varainces and t-stats (p-values).
Answer: Newey-West produces standard errors for coefficients estimated by OLS regression. The error structure is assumed to be possibly heteroskedastic and possibly autocorrelated up to some specified lag. Any autocorrelation at lags greater than that is ignored.

Newey West estimator, application


optical chemical structure recognition from images

Question: I want to recognize name of the chemical structure from the image of chemical structure, like in the given image it is benzene structure I want to recognize that it is benzene from the image(I should be able to recognize all these structures as benzene) What way I could follow to achieve this? (like this given any structure I want to recognize the name of it)  .
Comment: your question has no question mark (?). What is it that you want to know?
Comment: I want to recognize these benzene structures as benzene
Comment: Ok, and what is your question?
Comment: What way I could follow to achieve this? or is there any similar work I could follow
Comment: Do you want to only recognize if it is benzine (i.e. is it benzine yes or no) or do you want to recognize the name of any structure?
Comment: Yes!! I want to recognize the name of any structure given in the image
Answer: What way I could follow to achieve this?

Create a dataset with image-label pairs.
Create a classification model.

I don't think you will find any algorithm "out-of-the-box" for you to use.
You might have a look at some paper to see the kind of approaches they have.
I would recommend you look at these:

https://arxiv.org/ftp/arxiv/papers/1802/1802.04903.pdf which uses convolution neural nets and a heatmap as an attention mechanism. It even deals with noisy images.
https://web.stanford.edu/class/cs231a/prev_projects_2016/optical_recognition_of_chemical_structures.pdf which tries to identify hand-drawn structures. It uses a sort of edge detection algorithm for recreating the hand-drawn structures.
Comment: Thank You!! @Bruno GL, I will go through these papers.
Comment: @LalitVyas great I could help. If you think like your question has been answer, feel free to accept this answer.
Comment: sure @BrunoGL :)
Comment: @lalit vyas did they work?


can a virus cause programs to open on my computer?

Question: I had 18 viruses on my work computer and programs and even video games showed on my hard drive that I've never played sites I'd not looked at showing open all day?? Can a virus or maleware cause this?
Comment: I am sorry about it man. Did you try to reproduce it ? I mean cleaning up your hard drive and getting the same result due to the malware effect. If yes then you have a point to prove. Unless it is pretty hard to prove it since a malware opening something from your computer is as same as you are opening it on your own. Same uac permission which it got from you during some of your software installation. Good luck.
Comment: I lost my job over it. Any way for me to prove that?
Comment: Proving it is going to be difficult, since much malware runs in the same context as the logged-in user.  Your best hope would be to look for conflicting logs, such as any logs that show you on those web sites or starting those games when the office isn't even open.  This is likely to require the cooperation of the people who fired you, though.
Answer: Yes, it can. Once it gets/bypasses the user account control.
When you are not careful enough while installing something then you might invite a malware inside. Once you have given permission (User Account Control permissions) to run a software that contains malware, then officially you are granting rights to it.
Now you opening a program or the malware opening a program wouldn't make much of a difference to the os since you both posses same rights.
It is quite easy for any malware to do whatever they want. So opening programs are just a child play for a malware. Imagine what will happen if a keylogger is installed and tracks all your keypress, gathers your sensitive information like bank account passwords and passing it outside. Horrible right? One solution could be doing a clean sweep with a good antivirus software and keeping it updated.
Bottomline: Always know what you are installing.
Comment: Even without administrative rights (which is what UAC is about) a program can do *a lot* (including installing arbitrary additional software and starting it) unless the PC is really locked down.


attach "1" for the bias unit in neural networks. what does it mean?

Question: In the image below the instructor says attach a "1" for the bias unit in neural networks. what does a "bias unit"mean in neural network?
Answer: It allows you to account for some static offset in your learning process. To illustrate, consider the output of your first hidden layer without the bias unit.
h = sigma(W * x)

Here W is the matrix of your layer weights, and W * x is the matrix-vector multiplication between these weights and your input. sigma is your nonlinearity operating on each element of the result. Now consider what this looks like With the "bias unit".
h = sigma(W' * [x, 1]) ~ sigma(W*x + b)

Here, W' is your weight matrix with new entries associated with the "bias unit", and your new input is your original input with a 1 concatenated to it. You can think of this as being equivalent to your original matrix multiplication W * x plus some bias term b.
I will have to dig for the sources on this, but conventional wisdom is that you don't need the bias unit in modern architectures. If it's for a class though, I'd say use it if that's what you are instructed to do.
Answer: You always include bias. Try to visualize it from math standpoint of view. In a single layer, you're learning to fit linear function to your input.
$
f(x_{i}, W) = Wx_{i}
$

By adding b you can kinda move this function around the plot up and down, so you can fit better.
$
f(x_{i}, W, b) = Wx_{i} + b
$

When it comes to neural nets, we're using something called the bias trick. We combine weight matrix W and bias vector b into a single parameter. We just add additional dimension to our input data X with a constant value. Now your scoring function becomes this:
$
f(x_{i}, W) = Wx_{i}
$
and it makes implementation much easier as bias becomes just another parameter we'll be optimizing.


Wireframe overlay is not working

Question: I'm a beginner in blender, I use the AMD kit (motherboard, processor and video card) I was taking a course and ended up being stopped by a problem - my Wireframe overlay doesn't work, I've tried everything, uninstalled, updated blender and my video card driver, and nothing solves it. Can someone help me?
Answer: Interestingly, there is another location in the UI where you can try to turn this feature on, and, strangely enough, turning it on in one place doesn't turn it on in the other place. So it may not be exactly the same feature in some sense. But it looks the same, as far as I can tell. So it may work for you to try this as a workaround.
Go into the Object tab (not the Object Data tab) of the Properties Panel. Expand the Viewport Display section, and then click the Wireframe checkbox. Visually, this feature seems to be the same as using the overlay function. But as I said, the overlay checkbox will not be affected by clicking the display checkbox here. I don't know why.
Let me know if this works for you.
Comment: Obrigado pela resposta amigo, porem, infelizmente não funcionou! mesmo assim não aparece o wireframe

Wireframe overlay is not working


Adjectives for a person with a certain belief

Question: What do you call someone who believes in using other's resources instead of wasting his own purely because of the availability of it and has a motto of "why use mine when I can use others'?"
Answer: Obviously the go-to is selfish. You can look up synonyms for that pretty easily if you needed something more latinate or particular.
Going beyond that, the other people having left their resources where he could get to them was a moral hazard that caused him to act as a free rider, using shared resources without contributing. (If they aren't intended to be shared with some people, he's just a thief.) When there are too many people acting that way towards a shared resource, it's called the tragedy of the commons.
Answer: More informally, there's the word moocher: (MW)

a person who is supported by or seeks support from another without
  making an adequate return
unfortunately, too many people at the community potluck were moochers
  who didn't bring any food of their own
Synonyms
bloodsucker, freeloader, free rider, hanger-on, leech, parasite,
  sponge, spongerRelated Words dependent; deadbeat, idler; flunky (also
  flunkey or flunkie), henchman, lackey, satellite, stooge, sycophant,
  toady, yes-man; cheapskate, miser, niggard, piker, scrooge, skinflint,
  tightwad
Comment: The clearest and most common of these is probably "freeloader".
Comment: That reminds me of the smart answer to "What brand do you smoke?" Ans. OP's--Other People's.
Answer: A "fill in the blank" vampire... A parasite, a leech, someone above mentioned Sycophant; a personal favorite word of mine but that really doesn't apply... as Sycophants don't necessarily aim to gain anything, they just flatter to the point of it being tragic.
If you are speaking in terms of mythology; you could say succubus for female; and incubus for male, adding a "pre-noun" such as "you're a "financial incubus" (the succubus and incubus were typically only used to describe "total" consumption of the victim. They slowly over time, would either devour or destroy their victims, soul, spirit, heart, passion, lust for life, and so forth.
Answer: "Resourceful" is the euphemism we would use for those types in grad school. The word carries a neutral connotation and conveys the idea you mentioned.
I'd describe a person like that as scrappy, informally.
A phrase that comes to mind is "why reinvent the wheel?"


Recovery of corrupt .mov file from dash cam

Question: Yesterday on the way to work I was run into by a truck. I felt relaxed that I had my dash cam running only to find out last night when I tried to retrieve the commute file that it could not be opened.
There are lots of .mov files on the sd card but 50% or more can not be opened (and do not display a thumbnail in Mac either.)

I have tried to open in; Quicktime, VLC, Final Cut Pro and the guys at work who edit videos have tried also in various applications. I've also tried a few 'repair' apps and even Handbrake (somebody suggested to try to convert it to mp4.)
When I open the file in media info, I see this;

General
  Complete name : /Users/cbiggins/Desktop/AMBA3984.MOV
  Format : MPEG-4
  Format profile : QuickTime
  Codec ID : qt   0000.00 (qt  )
  File size : 302 MiB

If I open one of the functional files, I see this;

General
  Complete name : /Volumes/NO NAME/DCIM/100VIDEO/AMBA3957.MOV
  Format : MPEG-4
  Format profile : QuickTime
  Codec ID : qt   0000.00 (qt  )
  File size : 17.8 MiB
  Duration : 9s 710ms
  Overall bit rate mode : Constant
  Overall bit rate : 15.4 Mbps
  Encoded date : UTC 1970-01-03 14:29:27
  Tagged date : UTC 1970-01-03 14:29:27
  AMBA :

Plus big sections for video and audio (which i left out for readabilities sake.)
I don't know what is going on and considering the file is over 300mb, there is something in it. I just really need help recovering this file.
Answer: I was able to recover the file using Yodot Mov repair.
I'm going to use that and a combination of untrunc for the rest of the files.


Arduino GPS Camera

Question: I am working on a project through my school. We are going to be shooting cameras on spikes into the ground beside grid roads for tornado tracking. The spikes will be equipped with two cameras. My job is to design a system to track the spikes. I need to get GPS location and send it to a computer in the truck. I was thinking of using an Arduino. I need to send the GPS info (and possibly temp./air pressure) to the truck. I need as much range as possible as one of the spikes might be thrown by wind. We are hoping to keep the cost under $250 per spike.
Comment: Do you have size constraints?
Comment: What's your minimum acceptable range?
Comment: We don't have a size constraint set yet, but it can't be too big. No more than 4x4x4 inches. For minimum acceptable range, probably about 5 miles. Although the more the better. These things may be thrown by a tornado.
Answer: I recently bought two XBee-PRO 900HP's ($40 each) and I think they'll do nicely for your purpose. Great range (although I haven't tested anywhere close to the range you need). The spec claims up to 28 outdoor line-of-sight miles. Setting them up was really easy. These are new modules so you might have trouble finding decent tutorials on the "API mode" but you can probably get away with the default serial mode. These can be powered directly from the Arduino's 3.3V pinout. I can't stress enough how easy I was able to go from zero to sixty with 'em. The DigiMesh technology may be incredibly useful given you'll have an array of these spread out geographically. Since you'll be transmitting binary data (the images) I guess you'll have to base64 them. In API mode (aka not basic serial) I'm fairly certain you could transmit the raw binary data without any conversions other than having to split it across multiple packets. You'll have to fiddle with the baud rate based on your range, how much data your transmitting, and how fast you're doing it.
Another option, and I'm not sure how expensive this would be, is to give them all cellular data connections. You'd just have to setup a web server somewhere with a simple API. This would probably end up being easier to get working assuming you're in an area that has decent cell coverage and you know how to setup a web server (or know someone who does that's willing to work with you).
I think an Arduino Uno (or similar) would be enough but that would depend on the size of your imagery. You'd most likely have to have another chip buffer the image and then pass it through to your own buffer on the Arduino. An Arduino Pro would also work but would take considerably more effort to get up and running. It also doesn't have a 3.3V regulator built in. The new Arduino Due might be worth a look too.
In the same project (and device, for that matter) that I'm using the XBees, I'm using a GPS. Specifically the Fastrax UP501. Most of the GPS modules that I looked at are 3.3V so this is another reason to use an Arduino that has an onboard 3.3V regulator. Sparkfun has an epic GPS buying guide I'd highly recommend you take a look at. A 1Hz update speed should be more than enough unless you're trying to track these things as they fly through the air. Feel free to take a look at how I implemented GPS (using the TinyGPS library) in the CaptainShip module.
Sparkfun has a good selection of weather sensors but you may have a place already in mind that has more accurate and precise instruments.
As far as durability goes that'll be up to the design of the spike itself.
EDIT: A few other things for you to consider in a project like this. Granted, I've never done something quite like this myself, but this is how I'd probably end up going about it.

What's the power source? Solar? Battery?
How long can I make this power source last? The XBee and GPS that I mentioned both have low power modes.
How can I monitor the power source? Alert the server/coordinator of the issue.
With a properly configured XBee you can remotely upload sketches to your Arduino array without the need for direct access. This could save you a hell of a lot of time, or may not be important at all.
How many IO pins do I need? This will play a huge role in determining what Arduino you'd choose.
RAM is something incredibly limited on these devices too. As I hinted above, I doubt you'll be able to fit the entire image into the Arduino's memory. You'll need not only a way of interfacing with a camera from the Arduino but a way to store the image elsewhere.
Sparkfun has a few CMOS cameras to choose from but the documentation is severely lacking.
Comment: Thanks, this is a lot of help. We don't actually need to send the picture to the truck, just gps and info from the sensors.
Comment: I'm glad I could help. Since you don't need to send the photos from the camera, that will greatly reduce the constraints on your communication platform.
Comment: @bmandesign Also, if this answers your question please click the "check" next to it. If you have more questions feel free to edit your original question (as long as it's relevant) or open a new question onsite.
Comment: Note: You **can not** run an XBee pro off (most) arduino's 3.3V rail. The XBee pro needs ~220 mA supply current during transmission. The Arduinos generally use LP2985 3.3V regulators, which are rated for a maximum of 150 mA. As such, the regulator will likely shut-down when the SBee tries to transmit, leading to brownouts and hard-to-diagnose issues.
Comment: Thanks for the info, I wasn't sure of the exact ratings. When using the XBee Pros off the 3.3V pin I didn't encounter any crippling power issues but it was clear the level of current it was drawing.
Answer: Under $250 per spike with twin camera & GPS? Use a mobile phone. Find a make/model of phone that has the features and that you can create software for (either by jailbreaking it or writing an app) and use that. $250 puts you squarely in the territory of being able to walk into a phone shop, find a decent (if unfashionable) phone with pre-paid SIM / internet etc. and then do a deal for a big stack of 'em.
At the cheap end, find something common but worthless that you can get in bulk from recyclers / ebay / the bins at the local phone shop. There's some very hackable Nokias out there (N900 and its predecessors) which plenty of people are running Linux on.
Another alternative - there are GPS-GSM trackers all over eBay for less than the price of an arduino. Slot in a SIM card and a pair of AA batteries, push the button and nail it to the ground.
Both cases, range is just about infinite. Also, (re)programming a phone will be far more useful to your career than programming an arduino.
Third option: Take a GPS with you and tag where you put the spikes...

Arduino GPS Camera


How do Andalites have babies?

Question: Is it said anywhere in the series how Andalites have babies? The same way as humans do, another way (explained please) or it isn't told in the Animorphs books?
Answer: They have male and female, so they use sexual reproduction. Being children's books the details are probably not going to be mentioned.
(I should add that, from a biological standpoint, having male and female, and reproducing sexually, does not necessarily imply that the males and females play the same roles as in human reproduction. There are a few species on Earth where what the 'male' does and what the 'female' does is rather different.)
Answer: They don't lay eggs
In a Discord interview on 1/13/2018, Michael Grant (the co-author of the books) said that he did not think Andalites laid eggs.
No recording or transcript of the interview exists, but there was a summary compiled of what was said.

Q: Do Andalites lay eggs?
Grant doesn't think it's likely.

As far as I know this is the only official word that's ever been said by the authors about Andalite reproduction. Unless you count stuff like this.

How do Andalites have babies?


iotop but for particular disk?

Question: Is there a tool like iotop but for monitoring IO on specific volumes?  (Or perhaps I missed a way to filter iotop?)  If not is there any way to get at this information via (say)/proc?  (dstat etc. only show aggregate activity across all processes per volume, whereas I'm interested in seeing how much each process is contributing.)
Answer: This isn't an ideal answer, but this will tell you, every second, what process wrote the most, and how much it wrote, to a given disk (in this case /dev/sda):
dstat -tdD /dev/sda --top-io

You'll see something like:
Comment: this is helpful but it doesn't seem to limit the io reporting to the disk you specify... no matter what disk I pass on the command line, the top io process comes up.
Comment: oh I see, the io on the disk is on the left, the process is on the right, and the process isn't limited to the specified disk, but the read/write on the left is. thanks
Comment: @stu Yes, exactly. There may be IO to other disks too, but this should be only for the disk you specify.
Comment: for anybody else looking, I hadn't heard of fatrace, it doesn't tell you how much data is moving, but it does tell you what files, and you can limit it to a filesystem.
Comment: hmmm... getting back to this, it looks now like I read this wrong. the process is the most expensive process overall (including all disks it writes to) and the io going to the disk is on the left, but that doesn't actually mean that the most expensive process is the one  doing all the writing  to the disk in the left column, does it? really hard to read.
Answer: Check out fatrace:
For example, cd into the partition you want to (in my case, mount point /hdd) monitor and run
sudo fatrace -c -t

Then, for example a touch /hdd/x will show:
16:11:05.278541 touch(179482): + /hdd
16:11:05.278541 touch(179482): CWO /hdd/x

Details:
Usage: fatrace [options...]

Options:
  -c, --current-mount       Only record events on partition/mount of current directory.
  -o FILE, --output=FILE    Write events to a file instead of standard output.
  -s SECONDS, --seconds=SECONDS Stop after the given number of seconds.
  -t, --timestamp       Add timestamp to events. Give twice for seconds since the epoch.
  -p PID, --ignore-pid PID  Ignore events for this process ID. Can be specified multiple times.
  -f TYPES, --filter=TYPES  Show only the given event types; choose from C, R, O, or W, e. g. --filter=OC.
  -C COMM, --command=COMM   Show only events for this command.
  -h, --help            Show help.

Answer: As there are no answers yet...
I do not have an easy suggestion (like an iotop switch) but if this is important to you then you may write a FUSE module which just remounts the file systems elsewhere (chroot for the process to be examined) and counts the amount of data read / written. That should be a rather easy adaption of existing modules. You may ask the FUSE community which might be the best existing solution to start from. Probably even their demo module will do.
Answer: You can use iostat to monitor disk I/O for performance issues.
$ iostat -xd /proc

Comment: that splits up activity by disc, but not by process which is the key feature of iotop
Comment: Why add `-d /proc`? That will never give anything afaict, because `/proc` is not a device. You'd want to run it without that to see all devices, i.e. `iostat -x`. Heck, even the `-x` can be left out if you're not looking for obscure stats like "aqu-sz". Other than that, though, this is the tool I was looking for. It doesn't do by process, but I have one process reading from multiple disks and dominating my iotop stats, so I can estimate how much data is read from each device. Thanks!

iotop but for particular disk?


What happens if CT ratio entered wrong in 3phase meter

Question: I have HT connection with PREMIER 300 - SECURE METER,
CT operated at 5:2.5. But in the meter, the ratio is showing 1 instead of 0.5.
My question is whether the ratio matters or not.
Comment: My response is that capitals matter. If you have a product name in your question then it is not clear because the capital letters are missing. So is the link to the datasheet for the meter.
Answer: If your meter is assuming one ratio, and it's actually a different ratio, then the meter will read incorrectly.
Comment: Thank you sir. Actually 7-8 months ago the PF is above 90 for 20 to 30 KVA load and 20 KVAR capacitor. From some months the PF decreases very low at same load and same capacitor now to catch the PF connected 60 KVAR capacitor for same load what is the problem.
Answer: Of course the ratio matters. You will get incorrect reading.
Furthermore the applied burden can influence the transformers ratio. So please ensure that you are using the right transformer for the right burden.


Are cupboards safe in my house?

Question: I know chests are safe, the items that I put there will stay forever. Is that also true for cupboards? Because I like to separate chests according to the item category.
Comment: I'm sure every container in your house is safe.
Answer: I'm pretty sure that all containers in your house are supposed to be safe, there should be no difference between cupboards, dressers or chests. I've been keeping my stuff for a long time now in all kinds of containers in my home, nothing has vanished so far.
There is also a loading screen tip saying

Items can be safely stored in any container in your house.

I wasn't fast enough to get a screenshot of this loading screen
Comment: So... does this mean that if I store stuff in certain crates around town that I should be worried about items disappearing? That will change my gameplay... crap, now I'll have to move all my crap into a house... wait, I never bought the f*ing house... grrr... off to buy a house!

Are cupboards safe in my house?


What is the best way to represent Spearman's correlation graphically?

Question: For my thesis research I have to do Spearman's correlation tests on a set of ordinal variables. I would like to represent the correlations graphically to include them in the report and give a clearer idea of what is the relationship between the variables.
Since the Spearman's is on ranks, is it most appropriate to make a scatter plot with the ranks or with the actual data?
I was also wondering whether it is appropriate to include the graphs with data that do not give significant results, or if only significant ones should be represented.
Comment: If the variables are indeed ordinal, it means that the steps between levels don't carry known meaning. I can't think of a scenario where you'd want to use the "actual data" in a plot, as numerical differences between ordinal categories are not actually meaningful - if they were, the data would not be ordinal. I'd argue ordinal data can't really be represented as anything *but* ranks.
Comment: > I was also wondering whether it is appropriate to include the graphs with data that do not give significant results...

Depends on how you frame it. Ideally for each graph you show, you'd have enough data to say "here's the trend seen in the data AND here's a statistically significant test rejecting the null that this apparent trend is just a fluke / random noise." If your sample's not large enough for statistical significance, it may still be OK to include the graph with an honest description that "this looks like an interesting trend, but we'll need more data to be sure (future work!)"
Answer: There is a case for both graphs. A scatter plot of ranks shows, as it were, Spearman correlation's view of the data; a scatter plot of the original data shows your view of the data. What might be especially interesting is to show some examples where the relationship is monotonic but strongly nonlinear.
However, a problem could arise with ordinal data where there may be many ties, so you would need to think how to show the frequency of each distinct pair of values directly.
There is scope for a scatter plot matrix or pairs plot to show many plots in one image.
Your question is drifting into territory where only your advisor or supervisor or someone familiar with local rules or styles at your institution  can advise on expectations.
Further, much depends on how far the readership is expected to be familiar with statistical methods, or (not at all the same thing) how far you are expected to be able to explain the methods you are using, including their strengths and limitations.

What is the best way to represent Spearman’s correlation graphically?


Squeak coming from rear wheel

Question: I have a single speed bicycle that is less than one year old and probably has a mileage less than 100 km / 60 mi. I've recently noticed that the back wheel on the bicycle is giving out a a squeak on almost every revolution. The sound is similar to the sound of the wheel rubbing against the brake pads, but i've verified that this is not the origin of the sound. What i've also observed is that the squeaking happens only when i'm putting my full weight on the bike seat. It must also be noted that i'm a fairly heavy person i.e. 105 kg / 235 lbs and the maximal rating for the bicycle given by the manufacturer is 120 kg / 265 lbs. What could be the root cause for this issue?
Comment: There's a lot of different things that could be causing this. We need more information about the bike and the symptoms. Showing some images of the bike would be a good start.
Comment: I've had similar sounding issues in the past, all be it with disc brakes.  Also being a larger fellow when I got up of the seat and started peddling hard got the squeak.  Turned out the problem was flex in the QR skewer was enough to take the rotor out of alignment.  Might be a bit of a reach you're experiencing the same issue.
Comment: could it be that the tyre is rubbing against the frame? Or the spoke tension is low, and the wheel deforms under load, causing contact with the brake pads?
Or something different altogether: your shoe rubbing against a crank arm?
Comment: Does it squeak when coasting (not pedaling) or only when pedaling?
Answer: As mentioned in the comments above there could be many causes of the noise as some have listed there. Both @Hursey and @Burki I feel have good theories for the squeeking wheel of your bike. Especially considering the info given in your question, specifically that your riding weight is approaching the limit of the bike, which has rim brakes and is in it's break-in period based on the low milage.
Properly set up rim brakes have 1-2mm of clearance between the rim braking surface and the pad. When off the bike and checking for brake rub by spinning the wheel, one may not detect any rubbing and also find the pad to rim clearance appears adequate throughout the rotation. Note the presence of any run out of the rim as it spins (is there an area of "wobble") even if very small and doesn't contact the pad.
When the bike and wheel are subjected to riding forces (your weight and the force of peddling), some degree of deformation of the frame and rim occur. An already narrow clearance of a mm or two can be lost. A slight run out in an area of the rim can be exacerbated by the weight and force of riding and will now cause rim to pad contact.
Spoked wheels go through cycles of loading and unloading with each wheel rotation.  At any point in the rotation, there are spokes straining and bearing the weight and forces of riding while the opposite spokes become slack. This cyclic loading can cause loosening of the spoke nipples, causing the spokes to become unequally tensioned and the rim eventually comes out of true.
Most bikes through a wide range of quality and cost are specced with machine built wheels. Equal and adequate spoke tension (which makes a strong wheel) may not be a trait of most mass produced wheels. With cyclical loading loose spokes become worse quickly.  One of the things a quality bike shop will offer with their free post-break in tune up is rim trying or at least checking for adequate and even spoke tension in the wheels.
All this to say that theres a high probability the squeaking is brake rub from rim deformation.  You should have a qualified mechanic bring the spokes up to the proper tension.
You may want to check and modify the tension of the seat clamp bolts and also the seat post clamp.  These are two spots that can cause noise that can seem to come from elsewhere on the bike. See if the noise persists when you're off the seat.
Comment: Thank you for this in-depth answer. I'll have to see a professional since this problem is obviously too hard for me to solve on my own.

Squeak coming from rear wheel


How to add additional information in a neural network other than putting as input data?

Question: I am trying to use a neural network to predict final concrete strength. I have used material properties of concrete as input data. Now if I want to add some additional information like early age strength, is there any way to put them in the hidden layer? I mean other than using as input data?
Comment: @ Ayesha Munira Chowdhury...can you let me know how did you finally add additional input to the network without additional input data ? What did you do finally? I am working on similar stuff.
Answer: If your inputting data, it will always be an input :). But it is definitely possible to add in certain inptus after the first hidden layer. But what is your reasoning behind this? Why would you want this?
You should just input all your data in the first layer, let the neural network figure out how to use the data effectively itself. The neural network is like a black box, you put something in and something comes out - don't interfere too much by adding seperate inputs to the hidden layers.
Comment: Ask what the professor has in mind.
Comment: Thanks for your answer! :) My Professor wants me to work on connecting Bayesian theory with Neural Networks.I have previously used concrete material properties as input data and received final concrete strength as output. Recently, I used early age concrete strength as additional input data, and that way the neural network predicted the final strength better than before. But then my Professor said that it's too obvious that any neural network with more input data would preform better. That's why I was asking if there's any way to put additional information other than putting as input data.
Comment: Thanks for your reply. I finally worked out something recently. :)


One small confusion on $\epsilon$-Greedy policy improvement based on Monte Carlo

Question: I'm working on the RL book of Barto and Sutton, the author has provided the proof based on the policy improvement theorem, I can fully understand the inequality, but for the first equality, it really confuses me. why does $ q_{\pi}(s,\pi^{'}(s)) = \sum_{a}\pi^{'}(a|s)q(s,a)$ holds? I guess the reason here is because  $\pi^{'}$ is stochastic, but where the summation come from?
Comment: @Neil Slater I have posted the question here, thank you for the help
Answer: On page 96, the formula is stated.
It defines how can we evaluate the $q$-value for the policy $\pi'(s)$.
Given state $s$, $\pi'(a|s)$ is the probability that action $a$ is taken given that we are at state $s$ and if we take action $a$, we should expect a $q$-value of $q_{\pi}(s,a)$. We should then consider all possible cases and sum them up due to the total law of expectation.
$$E(R|S)=\sum_a P(A=a|S)E(R|s,A=a)$$
where $R$ is the reward, $S$ is the state, and $A$ is the action.
Comment: Appreciate the help, yes, I understand now. But based on the definition, $q_{\pi}(s ,a)=E(R|S,A)$, so $q_{\pi}(s ,{\pi}')$ should be something like $E(R|S,A'={\pi}')$?
Comment: I think on page $96$, the meaning of evaluating the $q$ value when the action is replaced by a policy is defined and it has to be defined based on entities that have been defined earlier. $q(s,a)$ is defined earlier.


Change boot entry names and grub background?

Question: How do i change the names of the boot entries and the background of the boot menu?
Answer: Install Grub Customizer.
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer

Run it.
This program allows you to edit just about every aspect of Grub.
Have fun with it, but be careful! :)
Comment: This is possible to do in the OS without the use of an untrusted PPA.
Comment: 'Twas my pleasure (:
Answer: To change the GRUB2 background image, you should first get the splash image package:
sudo apt-get install grub2-splashimages

For 10.04, edit the 05_debian_theme file in /etc/grub.d:
gksu -b gedit /etc/grub.d/05_debian_theme

Look for the lines that identify the WALLPAPER and COLORS:
WALLPAPER="/usr/share/images/grub/Lake_mapourika_NZ.tga"
COLOR_NORMAL="white/black"
COLOR_HIGHLIGHT="black/cyan"

For 10.10 and up, edit the grub file in /etc/default:
gksu -b gedit /etc/default/grub

Look for the lines that identify the GRUB_BACKGROUND:
GRUB_BACKGROUND=/path_to_image/filename

As for modifying the menu colors on 10.10 and up; from what I can tell (GRUB2 wiki) it seems to be the same as I have listed above (/etc/grub.d/05_debian_theme).  You might have to experiment with it.  If someone knows for sure, please add a comment.
There are 16 colors available: Black, Blue, Brown, Cyan, Dark-Gray, Green, Light-Cyan, Light-Blue, Light-Green, Light-Gray, Light-Magenta, Light-Red, Magenta, Red, White, and Yellow.  Just be careful with the combinations, because it's really easy to make your GRUB menu difficult/impossible to read.
Once you're done, be sure to update grub:
sudo update-grub

Also, I should add that I gleaned most of this information out of the GRUB2 wiki.  Check that out if you have any questions.
Comment: On top of this if you want to change the names of the entries follow the instructions from this blog post (basically is the same idea of this answer but with the focus on the entry displays): http://ubuntu-install.blogspot.com/2009/11/grub2-title-tweaks.html
Comment: Just realized my answer was based-on 10.04.  I'll put in some edits for more-recent versions.
Comment: Ok, I answered this question almost year ago and got nothing but good feedback on it.  Why the downvote?
Answer: Grub customizer is a untested buggy and dangerous program. It simply duplicates entries and does not seem to work. Maintainers were wise enough to keep it out of the os, so beware. Just copy image to boot/grub and update-grub.
Answer: For edit the name.... open terminal and execute this command
gksu gedit /boot/grub/grub.cfg

And edit the names there.... At my config, it starts at line 93 with:
menuentry 'Ubuntu, with Linux 3.0.0-16-generic' --class ubuntu --class gnu-linux --class gnu --class os {

Example of name change:
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os {

To change grub background, I don't know how exactly, but I now that is on this file too!
Comment: Wrong method. Each `update-grub` execution rewrites the `menuentry` fields.
Comment: I already new that method, but anyways thanks for your help :)
Comment: This is still an excellent method, if you don't have a full linux install on the drive and just use grub to boot (a live USB, or just a HD with live ISO's for example)
Answer: To put a picture to the GRUB background,
1- Make sure you know your screen resolution.
2- Edit your picture (GIMP is very good for this) to the same resolution as the screen.
3- With root privilege, copy the picture to /usr/share/images/desktop-base/ which, on my system, is empty.
4- In terminal, update grub by execution of a command "sudo update-grub".
The new background will show on next startup.
Answer: I'm new to linux but I used this site to change the background in grub. The website is really easy to understand and doesn't require you to install programs to edit grub. Its just step by step using the terminal
https://sites.google.com/site/easylinuxtipsproject/beautifygrub
One thing I would say though is I struggled to get the background to change when I was saving the image as a .jpg. It was the right resolution and appeared to be in the right folder but it just didn't appear when I booted my laptop. In the end when I used the image editor I saved the file as a .pgn file and works.
Also the site fails to mention that you need to save your image in the Downloads folder once you rescale it.
Hope this helps.
Comment: "Site not found" anymore, shame the instructions weren't copied to here, although it sounds like more than a two step process
Answer: Instead of me typing out the answer on how to change boot entry and background I will let Chris Hoffman from Howtogeek explain it.
http://www.howtogeek.com/196655/how-to-configure-the-grub2-boot-loaders-settings/
Answer: open the terminal from the root directory using the command :
gksu nautilus

Just operate the terminal from your root directory and copy the any image in the boot/grub and update the grub using the command :
update-grub

now restart the ubuntu to see the changes made.


UI customisation principles and guidelines

Question: I am working on a project that requires catering for a large number of personas and scenarios. Key to meeting these needs  is a UI that provides a customised experience. I was wondering if there is any resources that provide guidelines on how to optimise design for customisation.
Answer: I think you don't need to change any existing principles or guidelines. The only thing you need to do is to be more thorough with the mapping of user mental models and customer journeys to work out where the similarities and differences are. This is the starting point for any customization decisions that you need or may not need to make.
I would also suggest that you consider techniques based on user behaviour and usage statistics like progressive disclosure of content/interactions as well as progressive reduction, which will eventually allow you to tailor the UI to the individual or group of users.
Answer: In addition to Michael's answer, I'd also like to add that there exist guidelines for product customization which are based on user research and put together by the Nielsen Norman group.
Quoted from the report:

Web technology allows organizations to move beyond one-size-fits-all
  interfaces and products — allowing users to define and design their
  own experiences. Users appreciate custom homepages and web-based
  design-it-yourself processes. However, our research shows that users
  often encounter severe usability issues when trying to accomplish
  customization activities.
This 93-page report offers 46 design guidelines based on our usability
  research. Discussions and 78 screenshot illustrations supplement our
  findings.
The report does not cover personalization — where a software system
  tries to predict individual users' needs automatically. It is solely
  about designs where users themselves employ features to manually
  customize or configure the UI or a product.
Comment: My main focus is on personalizing the user experience based on data that we accumulate over time. By providing multiple states to different UI elements we can surface content that is relevant to a particular user or user group. the main challenge is using design patterns, solutions that would account for current usage while also being adapted to future growth within the user data set.That being said I definitely need to put my hand on this report particularly because it deals with handing control to users over the type of experience they want to have.


Why does the Alcubierre drive require negative energy?

Question: The Alcubierre drive is an idea for a faster-than-light spaceship. It works by contracting space-time in front of the ship, and expanding it behind the ship. Physicists say that this requires the use of negative energy or exotic matter. But why is that? I mean, positive mass and normal gravitational fields do bend space-time. If we could get a hold on creating and manipulating large gravitational fields, wouldn't we be able to create this drive?
Comment: I'll stick with a thiotimoline drive.  Much easier to implement.
Answer: Bending spacetime is not enough, you will also need to do it in specific ways. The simplest way of visualising the difference is to look at the Raychaudhuri equation, which describes how masses move in a gravitational field. If a gravitational field is generated using only positive energy (more precisely, obeying the weak energy condition), gravity is always attractive. If you allow negative energy, you can get bodies originally converging to a point suddenly diverging.
In the case of the Alcubierre drive, you need to both expand the space behind you and contract the spacetime in front of you (although the Alcubierre metric actually requires negative energy EVERYWHERE, but I'm not exactly sure how to work this out).


Water Spray Simulation

Question: I am working on a project where water needs to be sprayed so to form 60 deg full cone from the spray nozzle in an animation. I have tried it with inflow and v cylinder but when water leaves out it does not exapand to 60 deg as required. Can you please give m advise how to achieve that? I have done hollow cone spray with addition of obstacle but need full cone spray.
Answer: Examining the subject at hand, it appears a better way would be to use particle drops instead of a fluid system.
The resulting cone can be easily controled.

The movement can be setup convincingly.

Create an emitter object. Since we'll use the normal as emission, the concavity of this object will determine the outcoming angle.Add a subdivision surface modifier so that the normal direction won't appear stepped.
Create a density weight group, in case you want more water to be emitted from the center.
Add a particle system. Since particle don't have substeps in Blender, we need to increase the frame rate. I used 240 fps.
Enter the vertex group as density for the emitter.
Decrease the gravity value, since we have a faster frame rate. To make the emitter use the subdivision modifier, check Use Modifiers. I use about 15000 particles in a short burst from frame 1-80.
During that burst, I want the particles to have more speed around frame 40 and less at the end. Hence, I animate the Emission value for the normal. I also added some random offset to fight the missing substeps.
Create a cube and smooth subdive it (or use *to sphere). Use it as the particle object. Add some children to each particle. There should be lots of drops.
In the compositing add vector blur. As a material I mixed Glossy and Refractions BSDF.

Sorry, the file is not in the finished state. Have fun.
Comment: Blender does support substeps for particles. They're located in the  Physics rollout > subframes
Comment: @Leander:I sincerely thank you for the above answer . The reason I need fluid simulation is to check the % wetting of the part being sprayed with water and to ensure that complete part is getting wet.

Water Spray Simulation


Use of twisted pairs with fundamentally single-ended DUT

Question: Let's suppose I'm interested in measuring the voltage response of a DUT to some imposed voltages. The DUT takes V1, V2, V3 as inputs relative to some GND, and outputs V4 relative to the same GND. All signals are below 100 kHz, and there's a 4 m run of wire. Is there any benefit in using four twisted pairs (V1, GND), (V2, GND), (V3, GND), (V4, GND), where for each twisted pair, one of the leads is bonded to ground, and the twisted pair is either stimulated (in the case of an input) or sensed (in the case of an output) by a differential circuit. The DUT can not be extended with differential drivers (it will be deep inside a cryostat at 300 millikelvin.)
Answer: Yes there is a benefit from using twisted pair for this kind of messurement as you minimize the chance of external electromagnetic fields to induce Energy into the messurement circuit and such change the mesurement result. If you can't use coaxial shielded cable, twisted pair is among the next best solution...
Answer: It really depends on the sensitivity of the signals, twisting them will make them less susceptible to magnetic field noise from magnetic loops creating noise. Twisted pair are still susceptible to electric field coupling (which is why ethernet uses a differential signal because differential signals are less susceptible to noise).
So it would still be good to provide a shield around the cables up to the Cyrostat if they are very low level signals (like accuracy in the 10s of microvolts or below)
But if they are digital signals then don't worry about it it will be fine


When is the next shmita year (as of 5772)?

Question: When is the next shmita year?  Is there disagreement about which year?  If so, which Jewish sects or traditions believe the shmita is in which years?  If you specify years since creation, please also specify the timeline with respect to the Gregorian calendar.
Answer: The last shemittah year was Jewish year 5768 (13 Sept 2007 - 29 Sept 2008)
The next few are:

5775 (25 Sept 2014 - 13 Sept 2015)
5782 (7 Sept 2021 - 25 Sept 2022)
5789 (21 Sept 2028 - 9 Sept 2029)

Note that some Rishonim (medieval rabbis) held that the shemittah is the year prior to the years mentioned above (See Tur CM 67) but longstanding normative practice is not according to their view.
Source: I remember when everyone was observing the last Shemittah, and it's every seven years after that. I checked Kaluach regarding the dates for Rosh Hashanna.
Answer: Per Pearlman YeC Moshe Emes series for the alignment of Torah testimony, science and ancient civ. volume III 'Bible Chronology, untying a knot'
TALMUD HAS IT RIGHT Holy temple 2 start Shmitta cycle in 3410 anno mundi so 3416 the first Sabbtical. HOLY Temple II end 3830 420 years later a partial year
3829 the last whole year a Sabbatical year. This year 5782 a Sabbatical yr.
5782-2021 (1 Tishrei - Dec 31) = 3761
5782-2022 (1 Jan till month end Elul) = 3760 start Christian era.
3320-3390 anno mundi Jeremiah 70 years Nebuchadnezzar yr. 2 until Cyrus proclamation described in Ezra.
3310 start Shmitta cycle year 1 (3760 -3310 = 451/450 BCE
3314 Ezra arrival yr. 7 of Darius-Artaxerxes b. Achashverosh and Esther.
3316 first Shmitta year (it , like all that follow, is divisible by 7).
3759 last Shmitta year before Christian era. -3761/3760 = 1 Tishrei 2BCE until end Elul 1 BCE
Assume no zero year.
3766 first Shmitta of CE is 1 Tisheri year 5 till end Elul yr. 6.
3829 last Shmitta of Holy Temple II the last full year of Daniel's 70 weeks (490 full years) From mid yr. 68 starting 1 Tishrei until mid yr. 69, month end Elul (the day prior to 1 Tishrei).
5782, this year, a Shmitta year that started 1 Tishrei and will end the day before the coming Roh Hashanna (1 Tishrei) that commemorates the creation of First Adam on literal day 6, the start of 1 anno-mundi. As when The Creator aka G-d of Abraham becomes Sovereign of the Universe, King of Kings, as now has human subjects who alone can serve G-d, via exercising our free will to do so (rather than opting to be in denial).
So mid 2021 till mid 2022 this coming Rosh Hashanah is a Shmitta year.
Comment: It would be helpful to use space to better delineate paragraphs in your answer, and bullets where relevant. This is very hard to read and understand
Answer: The shmittah years listed above are wrong.
The timeline has been lost and incorrectly started again.
The shmittah year was celebrated the year that Herod the Great laid siege to Jerusalem, in the year [Siege of Jerusalem (37 BC)]https://en.wikipedia.org/wiki/Siege_of_Jerusalem_%2837_BC%29
"The besieged suffered from lack of provisions, compounded by a famine brought about by the sabbatical year"
The Civil year would have started in the Fall, and would have been 38 to 37 BCE.
The siege started in the spring 37 BCE, and was over before the year was expired, and it was particularly a severe siege since it was also a shmittah year.
This was a 7th shmittah or 49th year, with the following year 37 to 36 BCE being the Jubilee year 79th. www.torahcalendar.com/Calendar.asp?YM=Y-37M7
Now add 50 years for each Jubilee Cycle and you get [14 to 15 CE as the next Jubilee year 80th.]www.torahcalendar.com/Calendar.asp?YM=Y14M7
There is no year zero, so 1BCE to 1 CE is just 1 year.
Add 40 more Jubilee years and you have 2000 more years, and it is [Jubilee year 120, 2014 to 2015 CE.]www.torahcalendar.com/Calendar.asp?PYM=Y2014M7
So .... [2013 to 2014 CE] our present year is:
 Spiritual Year 5999
Civil Year 5999
Year 7 in Shemittah Cycle 7
Creation Shemittah Cycle 840
Year 49 in Jubilee Cycle 120
www.torahcalendar.com/Calendar.asp?PYM=Y2013M7
Comment: Except the Jubilee year hadn't happened since about 600  BCE
Comment: It's correct that there is no year 0 in the Gregorian calendar, but that doesn't mean that 1 BCE to 1 CE is only one year - it means that 1 BCE **is** 1 CE.
Comment: Accepting your (torahcalendar.com) terminus a quo of the fall of 38 B.C., I come up with the fall of 12 A.D. as the beginning of the next shemittah year. The next closest multiple of 49 takes me to the year 2021 and falling back 7 years gives me the fall of 2014 (49 yrs. x 41 = 2009 yrs. + 12 yrs/12A.D. = 2021 - 7 = 2014). this is in agreement with the first answer.


Multicore hacker tools?

Question: Have a school project coming up in multicore programming. I'm interested in/have used hacking tools alot before, and was wondering if there were any good tools out there that could benefit from being implemented in OpenMP or some other parallel framework to speed them up. I was originally thinking password cracking but saw John the Ripper, etc all usually have multicore implementations. Any ideas? Honestly anything would be appreciated.
Answer: Most tools used by hackers do not benefit from multithreading because they are not computationally intensive. The ones that do, in particular ones related to credential cracking, are often written with multithreading or even GPGPU acceleration in mind in the first place. So I don't think you'll find all that many tools that are written like that, since only a small portion would actually benefit from it.
One hash cracking tool that is not multithreaded that may benefit from it would be aircrack-ng.

Multicore hacker tools?


Why does my cheese flavouring have a sweetish smell/flavour?

Question: I recently purchased a bottle of Cheddar Cheese flavouring (product link here)  hoping to use it in pasta. The product description says it is apt for pasta. However, it has a strong sweetish smell which feels very unpleasant. What can be the reason for it?
Comment: It may be the propylene glycol. It's the first item on the list of ingredients. It's often used as a carrier for artificial flavourings/extracts  But propylene glycol tastes sweet, so that's possibly what's causing it.
Comment: @Billy Kerr Interesting. Is there a way to somehow evaporate it or something leaving behind just the flavour?
Comment: I think if you try evaporating it you will probably also evaporate or destroy the flavouring. Propylene glycol boils at 188C or 370F, which is considerably higher than water. If you are doing this to avoid dairy produce, then maybe look at other alternatives such as nutritional yeast which tastes somewhat cheesy, or perhaps some kind of fermented tofu product, or vegan cheese product.
Answer: The aroma of a highly concentrated flavoring can be distinctly different from the taste it provides when used in food at a reasonable concentration. The only way to know if it'll taste weirdly sweet (or weird in other ways) in pasta is to use it in pasta.
Comment: I had added it in instant noodles and it had that sweet flavour.
Comment: That sounds pretty different from how you're meant to use it (in dough, rather than in sauce). Nevertheless, if that's what you want to use it for, you have your answer.
Comment: So adding it in dough is supposed to mute its sweet flavour? Someone in the comments mentioned making mac and cheese with it.
Answer: Propylene glycol is the first ingredient, and that ingredient has a notably sweet taste. It has a wide range of uses: from food (like your cheese flavoring product), to eye drops/artificial tears, to antifreeze.
Due to the sweet-ish taste, you'll probably need to counter that by adding some offsetting tastes to balance it out. Both salt and acid (like lemon juice) can help balance out sweetness, but you're definitely right to think that using it by itself will add sweetness


Salesforce1 Compact Layout

Question: Question regarding customizing Salesforce1.  On my contact record detail page, the upper section of the display can be controlled by the Compact Layout.  I get that with no problem.  But I dont know how to control the narrow section right below that.  Its sits just below the top section and above the detail section.  On my contact record, this section contains 2 icons (one is an Email icon, and the other brings up google? maps).  Similarly on the Account record detail page, there are 3 icons, google? maps, google? search, and a 'link' icon that doesnt work.  However, the leads and opportunity record contain no such section.
Answer: I believe those are special icons for just the Account and Contact that can't be modified. I also have a phone icon so I can call one of the phone numbers on the record. The link icon should link to the account's web page if you have one filled in on the standard website field.

Salesforce1 Compact Layout


File backing store for Jazz RTC? Database or file based?

Question: We currently use Clearcase for a large number of large projects. We use SQL Server as the file store in the background, and it has eventually reached a point where accessing files is just too slow.
Looking at GIT and Mercurial, we see a distributed VCS based on storing file differences - which has the potential to get much better local performance.
Does anybody know whether Jazz RTC has a file store backed by file differences or by a database? (The rumour mill is suggesting it is backed by DB2 :/ )
Answer: I would recommend on using Git for VCS and other systems for issue tracking, build servers, etc. The all-in-one solutions only go so far. Initially it may be easier to start, but you quickly run into the "weakest link in the chain".
Hope this helps
Answer: I suppose you mean Jazz RTC, which has a version control included.
Its Jazz RTC server supports DB2, Sql Server and Oracle.

However, a Jazz platform is very different from a DVCS like Git and Mercurial: it is an application Hub made to facilitate the communication between several software about the development lifecycle (requirements, versionning, changes, builds, ...).
The version control part is only a small portion of Jazz.
Answer: File access with RTC/Jazz source control is fast.
On the Jazz SCM dev team (of which I'm a part), we have a large repo. It contains tens of thousands of files, and hundreds of thousands of file states. The load time (on our LAN) is limited by network speed: I can load 50k files (roughly 500megs) in 10 to 20 minutes. On a faster network, it would be better.
On the server, changes are kept as deltas (ie, differences between versions) where appropriate. The Jazz server is backed by a database, but access is quick.
Comment: Excellent: any system would be faster that our sloow ClearCase ;) I didn't find much documentation on the "distributed" aspect (new in RTC3.x) of the version control on Jazz server though.
Comment: If you have questions about distributed source control with RTC, ask on the [newsgroup](https://jazz.net/forums/viewforum.php?f=1).


Problem with RequiredPlayerRange on spawners

Question: This is on the latest Minecraft version, 1.16.4
I have been trying to figure out how to get it to work with NBTExplorer. I changed the RequiredPlayerRange to higher then default amount which was 16 now its 40, yet whenever I save it and just restart my game to see if the changes applied it still defaults back to its original range yet still says 40 in the NBTExplorer.
went to ahead and checked on the official wiki of Minecraft to find I had to change MaxNearbyEntities as well, though I'm unsure what to do so I changed it to the same value, still nothing
update during writing!
found a command that might work?
<code>/data merge block -1537 39 771 {RequiredPlayerRange: 30}
</code>
standing above the spawner and counted 1 block off the Y coordinate
^ this gave me an error: that position is not loaded
Though, I have no idea what that could mean really.
Could someone explain why I am getting this?
Also, if you know of a different fix for the problem, please tell me!
Answer: Try this whilst standing on top of the spawner:
<code>/data merge block ~ ~-1 ~ {RequiredPlayerRange: 30}
</code>


Loading PHP MongoDB class with XAMPP on Windows 7

Question: Okay.
I'm trying to use MongoDB with Node.js and PHP/XAMPP on Windows 7, but I can't seem to install the PHP MongoClient Class at all.
I am a complete beginner with MongoDB and I have to say that if I wasn't committed to solving this I'd have given up by now.
 After lots of fiddling around trying to install the correct device driver version etc., I have come across yet another problem. But first, let me explain the steps I have taken so far.
Installed XAMPP v3.2.1, keeping all defaults.
Looked at phpinfo() on localhost:
PHP Version: 5.5.15. PHP Architecture: x86. Thread-Safe: Enabled.
Figured out where to download the software, as well as the correct version, etc.
Went to pecl.php.net/package/mongo/1.5.5/windows/.
At "DLL List" (PHP 5.5), I selected: `5.5 Thread Safe (TS) x86.
Went to PHP.ini (not the development or production version, but the actual one), and added 1 line: extension=php_mongo.dll. (line 887). No semicolon in front.
Started Apache.
Error: PHP Startup: C:\xampp\php\ext\php_mongo.dll could not be found on your computer.
I found out that when you manually type the file extension of a program that is already saved as a specific type, my computer simply prepends it to the existing one. The program was saved with the extension dll.dll. I got rid of that.
Restarted Apache.
Then I got this... Error: PHP Startup: Libsasl.dll is not found on your computer. Unable to load dynamic library C:\xampp\php\ext\php_mongo.dll. Try reinstalling the program.
I reinstalled the program. As I suspected, no missing file was magically created.
I then looked online to try to find this 'dll' file. After some searching, I was able to install Libsasl.dll via dll-files.com.
I restarted Apache.
Next problem:
Error: PHP Startup: Unable to load dynamic library C:\xampp\php\ext\php_mongo.dll - Access is denied.
I tried running XAMPP as an administrator. Same result.
The program is definitely there, but I can't seem to access it for whatever reason.
Why? I am getting quite frustrated with this and I would love everything to start working properly.
I have a hunch that it has something to do with read/write privileges but I don't know where to look.
Some help would be appreciated.
Answer: I was facing same issue, then after adding the path of the ".dll" file's folder to the environment variable as a system variable path, it worked. It is then able to find the file. At the end that was the only step which was stopping xampp to load the ".dll" file, although it was present in that folder. Often people miss this step as it is no where pointed out clearly.