Does deleting domain and removing property from Google Search Console remove a website from search results?

Question: I had a staging site and added it to my Google Search Console and got it indexed. Now I deployed the site to my main domain. I also deleted the old subdomain / staging domain, and deleted the subdomain property from Google Search Console, but it's still showing the subdomain in Google Search.
Answer: Deleting a domain will quickly get a site removed from search results.  Google will remove each page on the domain after crawling it and getting an error, usually with a 24 hour grace period unless it is removed with a "410 Gone" error. It may take Google a few weeks to remove the entire site, but some pages will usually start getting de-indexed within a day or two.
Removing your Google Search Console property has no impact on whether or not your site is indexed.  Google indexes sites that exist but which are not verifified in Google Search Console.  Google also decides not to index sites that are verified in Google Search Console.  When you are removing your site, I would recommend keeping your Google Search Console account because:

It will let you see how much of your site is still indexed after you deleted it.
You could submit a temporary sitemap to get Googlebot to come crawl the site more quickly and find that all the pages don't exist.
Comment: thanks for answering, but it have been more than 48 hours since the domain was deleted, and website property was removed from google search console, but still Google is indexing the website.
Comment: It will likely take 2 weeks for Googlebot to crawl most of the pages on your site.  If you have a lot of pages, it could take several months to get to all of them. You should get your Google Search Console site verification back so that you can monitor the process and submit a temporary sitemap for any URLs that haven't been deindexed yet.
Comment: all pages got removed on the very first day after deleting domain, but there is only the home page, that is getting indexed. Isn't there any way to  de-index it ?
Comment: It will get removed, but it may take a couple weeks.  In the mean time you could redirect the old staging subdomain to your main domain.


How can I sandbox a Wine application on Linux?

Question: I would like to run Microsoft Office programs such as Word but do not trust them, nor should anyone. Without running a virtual machine, is there a good way to sandbox a windows application to run on linux. I've tried using firejail (block all network access and temporary fake filesystem) with Wine but could not get Excel or Word to work.
Answer: You can run wine inside of docker containers to isolate it from your host system.
docker does not support GUI applications on its own, but it is possible.
Have a look at x11docker to run GUI applications in docker. There is also a description of short setups without x11docker.
There is also a ready-to-use wine image at docker hub: x11docker/lxde-wine
Example: wine on dockered LXDE desktop (needs a nested X server like e.g. Xephyr):
x11docker --desktop --home x11docker/lxde-wine

The image contains PlayOnLinux, too. Run Playonlinux with:
x11docker --home x11docker/lxde-wine playonlinux

(Option --home creates a persistant home folder for wine container to preserve installed wine installations.)
Disclaimer: I am the author of x11docker, sorry for advertising

Setup without x11docker to provide an independent answer. It lacks some x11docker security features, but basically it works and is much better than installing wine on host:
Dockerfile to build a wine+PlayOnLinux image:
FROM debian:stretch
ENV DEBIAN_FRONTEND noninteractive

# contrib for winetricks, stretch-backports for latest wine
RUN echo "deb http://deb.debian.org/debian stretch contrib" >> /etc/apt/sources.list && \
    echo "deb http://deb.debian.org/debian stretch-backports main" >> /etc/apt/sources.list

# Multiarch for wine32, wine, some often needed dependencies:
RUN dpkg --add-architecture i386 && apt-get update && \
    apt-get -t stretch-backports install -y wine

# helpful additions
RUN apt-get install -y fonts-wine winetricks ttf-mscorefonts-installer winbind

# wine gecko and mono
RUN mkdir -p /usr/share/wine/gecko && \
    cd /usr/share/wine/gecko && wget https://dl.winehq.org/wine/wine-gecko/2.47/wine_gecko-2.47-x86.msi && \
    wget https://dl.winehq.org/wine/wine-gecko/2.47/wine_gecko-2.47-x86_64.msi && \
    mkdir -p /usr/share/wine/mono && \
    cd /usr/share/wine/mono  && wget https://dl.winehq.org/wine/wine-mono/4.7.1/wine-mono-4.7.1.msi

# PlayOnLinux
RUN apt-get install -y playonlinux xterm gettext

CMD playonlinux

Command to run PlayOnLinux image:
# folder on host to store settings and installations
mkdir -p ~/winehome
# allow X access for user in container
xhost +SI:localuser:$(id -un)
docker run --rm \
    --env DISPLAY=$DISPLAY \
    --user=$(id -u):$(id -g) \
    --env USER=$(id -un) \
    --volume /tmp/.X11-unix:/tmp/.X11-unix \
    --volume ~/winehome:/home/$(id -un) \
    --env HOME=/home/$(id -un) \
    --ipc=host \
    playonlinuximage

Comment: Is there some tool/GUI that allows you to make use of this for gaming? Or can it get added to Lutris somehow for Windows games? [Is this really the most secure way to use Wine games and shouldn't you also add firejail if you use docker containers?](https://unix.stackexchange.com/questions/714165/is-it-possible-to-sandbox-wine-in-a-way-that-mitigates-all-security-risks-from-r)
Answer: Personally, I would implement security profile with some MAC for that. If you run Ubuntu, than out of the box you have AppArmor. It has lower entry level comparing to SELinux, so you have less chances for missconfiguration. You can restrict network access and access to filesystem, so that Word will be able to access only documents in dedicated folder.
BTW: from security perspective having Wine in your Linux environment is a bad idea as it makes you vulnerable to some range of Windows malware.
Comment: Okay, I will take a look at making an AppArmor profile. I just didn't think it would be sufficient enough to defend from Microsoft Malware. Also regarding the Wine vulnerability, I assume this is really only a risk if I choose to run a malicious .exe, Linux does not automatically run an exe using Wine unless specifically asked to open with Wine right?
Comment: That depends on your system configuration. I don't remember them exactly, but I have seen some approaches that allow Windows binaries to be transparently executed with Wine. I think you need to research a bit. First thing you can check is try to execute some Windows binaries you have in your system.
Comment: Worryingly whilst I had set executables to open in in vim if accidently double clicked, I discovered that I had some software installed called mono-runtime which executed the .exe on double click. Anyone who reads this please make sure you sudo apt --purge remove mono-runtime
Comment: @Joe Mono is something that helps you to get .NET (C#...) programs to run on Linux. If you don't need it, fine, but disabling the doube-click execution doesn't require uninstalling it - change the Mime configuration, done. ... Other than that, if you didn't do it yet, I recommend giving Libreoffice a try.
Answer: You can try Winepak, which is a Wine image of Flatpak.
Flatpak offers full GUI and sandboxing.
You'll have to build it yourself though.
Answer: You could run the program in a new user account that you don't use for anything else. Then any programs run under that account can only access stuff that can be accessed by that account.
Answer: sandwine is rather young (as of March 2023) and I don't have Excel or Word at hand to test the with sandwine, but it is a Wine sandbox with multiple options for X11 builtin and it may work for you. Please be sure to read the section on its threat model in the main readme.
PS: It would be interesting what issues you faced with firejail.


SQLite  - sql question 101

Question: I would do something like this:

select * from cars_table where body not equal to null.
select * from cars_table where values not equal to null And id = "3"

I know the syntax for 'not equal' is <>, but I get an empty results.
For the second part, I want to get a result set where it only returns the columns that have a value. So, if the value is null, then don't include that column.
Thanks
Answer: You cannot use equality operators for nulls, you must use is null and is not null.
So your first query would be:
select * from cars_table where body is not null;

There's no easy way to do your second operation (excluding columns that are null). I'm assuming you mean don't display the column if all rows have NULL for that column, since it would be even harder to do this on a row-by-row basis. A select statement expects a list of columns to show, and will faithfully show them whether they are null or not.
The only possibility that springs to mind is a series (one per column) of selects with grouping to determine if the column only has nulls, then dynamically construct a new query with only columns that didn't meet that criteria.
But that's incredibly messy and not at all suited to SQL - perhaps if you could tell us the rationale behind the request, there may be another solution.
Answer: Comparing to NULL is not done with <>, but with is null and is not null :
select *
from cars_table
where body is not null

And :
select *
from cars_table
where values is not null
    and id = '3'

NULL is not a normal value, and has to be dealt with differently than standard values.
Comment: I want  values to represent the column values
Answer: In SQL, NULL is an unknown value.  It is neither equal-to nor not-equal-to any other value.  All comparison operators (=, <>, <, >, etc.) return false if either of the values being compared is NULL.  (I don't know how old you are, so I can't say that you're 24, but I also can't say that you're not 24.)
As already mentioned, you have to use IS NULL or IS NOT NULL instead when testing for NULL values.
Answer: Thank you all for your answers.
Well, I have a table with a bunch of columns.
And I am going to search a particular car, and get the values for that car...
car   | manual | automatic | sedan | power brakes | jet engine
honda | true   | false     | false | true         | false
mazda | false  | true      | false | true         | true
So, I want to do ->
select * from car_table where car='mazda' and values not equal to false
So then I just iterate over the cursor result and fill up the table with the appropriate columns and values. Where values are columns. I guess I replace values with * for columns
I know I could do it programmatically, but was thinking I could do this just by sql

SQLite  - sql question 101


How can we find the eV value of molecular orbital diagrams for a given atom?

Question: It seems like sometimes the electron volt value of the molecular orbital is given but most of the time it just shows relative values of s p d orbitals. Is there some lookup table for such values?
Comment: It can be either experimentally determined (look up photoelectron spectroscopy) or just calculated with a computer (lots of QM if you want to find out more - start with the secular equations perhaps).
Answer: Exact values of MO energy are rarely given as they are difficult to obtain in anything other than relatively trivial systems. When they are given, it is often not even clear whether they are experimentally derived (Photoelectron spectroscopy, as mentioned by orthocresol), or computationally derived (by calculations to approximate the wave functions and their properties). For this reason, most MO diagrams presented are qualitative, derived from our knowledge of symmetry, orbital energy etc.
There is a book, The Organic Chemist's Book of Orbitals (Salem and Jorgensen) which gives the MO's of many simple, and slightly more complex  molecules along with computationally derived energies (in eV).
For anything more complicated, you could also try searching the literature, however this would probably just turn up very specific examples that people have calculated to support their research.
If you need specific energies for molecules, you might look into computing them yourself. Simple software such as Spartan does an acceptable job at computing MO energy, with a variety of computational methods available depending on how much computing power you have.


Is "wingman" strictly a military term?

Question: Does it have to be a potential combat situation for a pilot flying on another's wing to be called a wingman. If two aircraft are being flown in formation to a destination simply for the purpose of transportation, would the term wingman be used?  Is wingman used in civilian aviation?
Comment: I've never heard the term in civilian use. It's primarily a military term, as the wingman is there to protect and to assist - it's not just a descriptor of flying in formation.
Comment: @Dan Thanks.  Is there a term a pilot would use for someone who is flying in formation with them in a non-combat situation?
Comment: Yes, someone flying in formation with a lead aircraft is called the wingman.
Answer: While the combat military role of a wingman is established, the term is entirely appropriate and is used for non-combat formation flying as well.  And unless there is a better term, it would be logical to extend the use to civilian formations also.
Answer: A wingman is used in a combat situation, the function of the wingman is to protect the aircraft it is assigned to. example:
Aircraft A is tasked with a reconnaissance mission to take photographs in hostile airspace. Aircraft B is assigned to A as it's wingman. If during the mission an enemy plane is spotted, the wingman (B) will do whatever it's takes to protect the mission of A.
For formation flying, there is a leader of the formation but to my knowledge there are no special word describing the roles of each aircraft in the formation.
Comment: What you are describing is not the role of a wingman, but the role of a HVA CAP.  (High value asset combat air patrol)  The roles of flight lead and wingman are typically used in the context of a same aircraft type/same mission flight of two where both offer mutual support to the other.  The designated lead in this case is generally just the most senior, most qualified pilot of the two.  But that doesn't mean that the junior wingman won't swap and lead the formation when the designated flight lead directs.  In a flight of 4 there will be a division lead, a section lead, and 2 wingmen.
Answer: While the terms originated with the military, they are used in the civilian world when flying in formation. Formation flying does require training to be performed safely. As formation flying is not mainstream, getting the necessary training can be problematic.
One source is the organizations associated with Formation and Safety Team (FAST). They are "a worldwide, educational organization dedicated to teaching safe formation flying in restored, vintage military aircraft and civilian aircraft." Their training protocols are pretty much the standard for formation flying in the civilian world.
On their website they provide training and reference material. In all formation flying, there is a "Lead" and there is one or more "Wingman" or just "Wing". So, yes, the term wingman is used outside the military.

Is "wingman" strictly a military term?


Making mobs invincible

Question: Is there a way to make mobs invincible? I have already spent a while looking for it on google, but all I get is people telling me to give it a resistance potion effect. I am sure there is some attribute that I can give a summoned mob to make it invincible, but I don't know how to do it. How can I do this?
Comment: Yes, you can give them an invisibility potion effect, either using an actual potion or using the `/effect` command with the `@e` selector in 1.8 (snapshots)
Comment: @MBraedley He's asking about being "invincible" not "invisible" (I did the same thing at first glance)
Comment: Oh, yes, I see that now.  It should still be possible with potion effects
Answer: The answer is way simpler now you can now make mobs FULLY invincible. Here's how:
<code>/summon Cow ~0 ~0 ~0 {Invulnerable:1}
</code>
Easy! If you want to spawn any other mob, just change the "Cow" to the name of whatever mob you like. If you were to spawn a zombie, the zombie will still burn in daylight but will not take any damage from it.
IMPORTANT NOTE: When typing out the command, the mob's name must be EXACT. For example if I wanted to spawn a zombie, I cant type:
<code>/summon zombie ~0 ~0 ~0 {Invulnerable:1}
</code>
You will just receive the message: "Unable to summon object". Instead, you have to type the name of the mob with ALL NECESSARY CAPS:
<code>/summon Zombie ~0 ~0 ~0 {Invulnerable:1}
</code>
OR
<code>/summon Skeleton ~0 ~0 ~0 {Invulnerable:1}
</code>
mobs with two names will have their own name, e.g: zombie pigman :PigZombie, snow golem :SnowMan iron golem : VillagerGolem cave spider : CaveSpider  magma cube : LavaSlime ender dragon : EnderDragon.
Comment: A player still is able to hurt an "invulnerable" mob if they are in Creative mode.  Switch to Survival or Adventure to test.  :)
Comment: And also, for mobs like zombie pigmen, I think you could just type in __Zombie_Pigman__, or __ZombiePigman__. I don't think it would prevent you from spawning two word name mobs.
Answer: For simply making mobs invincible, this method is now outdated, see David Toh's solution using the new "Invulnerable" tag.

You need to use a resistance effect of level 5 or higher. This is the closest to a simple invincible tag we have at the moment, it gives the mob 100% resistance to damage, so is effectively the same thing. To summon a mob with an effect, you use the tags
<code>{ActiveEffects:[{Id: x ,Amplifier: x ,Duration: x }]}
</code>
So for an invincible skeleton, you would say:
<code>/summon Skeleton ~ ~2 ~ {ActiveEffects:[{Id:11,Amplifier:5,Duration:10000000}]}
</code>
The only way to kill this mob will then be either through mods, or using void damage (falling out of the world).
Extra Note: The mob may still de-spawn if it's not in a loaded area, to avoid this you can name your mob:
<code>/summon Skeleton ~ ~2 ~ {CustomName:Example Name,CustomNameVisible:1,ActiveEffects:[{Id:11,Amplifier:5,Duration:10000000}]}
</code>
Replace "Example Name" with a name of your choice.
In answer to the comment about using multiple effects:
You can have as many effects as you like by formatting your active effects section of the summon like so:
<code>ActiveEffects:[{Id:11,Amplifier:5,Duration:10000000},{Id:14,Amplifier:1,Duration:10000000}]
</code>
Full command for invincible and invisible skeleton named "Example Name"
<code>/summon Skeleton ~ ~2 ~ {CustomName:Example Name,CustomNameVisible:1,ActiveEffects:[{Id:11,Amplifier:5,Duration:10000000},{Id:14,Amplifier:1,Duration:10000000}]}
</code>
Comment: How could I make the mob invisible too? (Sorry if this is annoying) Would I add another section that is surrounded by the __[{}]__ characters and separate the two sections of __[{}]__ with a comma like this? __[{}],[{}]__ Or like this? __[{},{}]__
Comment: To add multiple effects, you add another set of {} into the active effects, like so: `/summon Skeleton ~ ~2 ~ {CustomName:Example Name,CustomNameVisible:1,ActiveEffects:[{Id:11,Amplifier:5,Duration:10000000},{Id:14,Amplifier:1,Duration:10000000}]}`
Comment: I'll add this to the answer so it's easier to read.
Answer: Thanks to @DBS for answering my question. For those who are wondering, this is what I was trying to accomplish with this newly gained knowledge. A flying boat. Here is the full command for those who want it:
<code>/summon Boat ~ ~ ~ {riding:{Id:Bat{CustomName:Plane,CustomNameVisible:1,ActiveEffects:[{Id:11,Amplifier:5,Duration:372000},{Id:14,Amplifier:5,Duration:372000},{Id:1,Amplifier:1,Duration:372000},{Id:2,Amplifier:255,Duration:2}]}}}
</code>

Making mobs invincible


Why advice to change adviser is rarely or simply not advised to be used in academia?

Question: In this forum, and in this question I noticed, in general,  that changing advisors are regarded as something that is bad and very difficult to achieve? Why members with high reputation on this forum, spread such a false information? or is that usual in academia, so the cases that actually change advisors are the exception from a majority of the situations in PhD programs.
I see people dont understand this question.
User with high reputation points on this forum, claim that you should drop or change PhD program, instead of changing advisors.
they dont provide any source or proof to support their claims.
Whenver this problem is brought, they tend to vote for closing question or delate comments.
Comment: I don't understand this question. The linked question seems to not back up the accusation at all.
Comment: @SSimon: why are you suggesting members are spreading "false information"?
Comment: I am starting to get the feeling that you either don't actually read what people write or is simply incapable of understanding basic English.
Comment: @SSimon It isn't illegal to be a bad advisor or to be a poor institutional fit for a student.
Comment: Right, but you have also not backed up your claim that this is being claimed by members of this community.
Comment: @SSimon In the post you link, the OP has already tried to change advisors and was blocked and threatened by his current advisor for doing so. There does not appear to be any support for the OP at that institution. Therefore, *in that instance* many people recommended that only a change of institution is possible. You don't provide any support for your own claims here except for this one bad example, and you seem to be reading the answers there as if they apply to all situations rather than that one specific situation.
Comment: Further, your responses here make no sense at all. Someone asked why you think people are spreading "false information" and you responded with a definition of what a "member of this community is." It is like somebody asked you what your favorite color is and you responded that you like cats - it suggests that you might be making accusations based on a language barrier.
Comment: In many cases, it's very true information: as usual things change by country, institution, etc. Don't generalize.
Comment: I think this is really clear question @TobiasKildetoft People, users at this forum, advice others to NOT change advisor, to rather change program!!!
Comment: In the linked question, the OP has explained why changing advisor is not possible in the specific situation.
Comment: I think my question is about users with high reputation score at academia. They suggest OP that it is better and more likely to change or quite PhD than to change advisor
Comment: because I never find any information or condition in PhD programs, that if you change advisor you need to drop studies. @ZeroTheHero never, and I googled it, and read through, if someone can provide something  substantial.
Comment: hmmm. member of this community means, user that log in and create account,
Comment: again, I dont understand on what you are referring @TobiasKildetoft you are not clear.
Comment: @BryanKrause isnt that illegal? to prevent him do that?
Comment: @BryanKrause really? you are not protected by law, or some sort of contract?
Answer: We say it because in the overwhelming majority of cases/countries it's true. If Glassdoor ever start including reviews of academic supervisors, you will see some really scary stuff. The longer you stay in academia, the more you see. That is why we try to warn people.
Comment: No-one officially prevents you. But also no-one can force a new advisor take you on, it's a voluntary task. Therefore no-one chooses to jeopardise their relationship with their colleagues for a lowly student they will never see again.
Comment: isnt that illegal?to prevent you from changing advisor?
Comment: oh, so there is some kind of cultural barrier. but what if these advisors are not from same department?
Comment: It's less difficult, but I have seen people rejected because of this nonetheless. They are considered "too risky".


Magento 2 Visual Swatch Image: Background of image is removed after upload

Question: This is the image that I upload to display on a visual swatch:

However, it uploads and displays like this:

How do I get the image to upload with the background intact?
You can view the uploaded image here: https://store.gnut.com.au/pub/media/attribute/swatch/swatch_image/30x20/c/r/cream1.png
I intend to increase the swatch size to 90x90px but I'll have to change themes away from Luma first.
Could the uploader be removing the background accidentally due to the small swatch size?
Answer: After changing all files to a .jpg extension instead of .png the problem went away.


Best software to fit molecular spectroscopy data

Question: I have some data from a molecular spectroscopy experiment, containing vibrational and rotational spectra, and I want to fit the peaks with Voigt profiles (one for each peak) in order to obtain the centers of the peaks. Do you know any software suitable for this kind of fit? I usually use Python (scipy, lmfit), but so far it didn't really work, as there are many peaks in one spectrum, so many parameters to fit for and I think that the fit gets stuck in a local minima, before reaching the actual parameters (but if you know a python package good enough for what I need, I am willing to try). Also, should I fit all the spectrum at once, or one peak at a time. If I do one peak at a time I get rid of the dimensionality problem, but the fit might not be as accurate as when I fit everything at once.
Comment: [Origin](https://www.originlab.com/index.aspx?go=Solutions/Applications/Spectroscopy) is very useful in spectroscopy, but it's [not free](https://www.originlab.com/index.aspx?go=PURCHASE/PRICINGANDORDERING&pid=1005).
Answer: For fitting of 1D data the Fityk code (https://github.com/wojdyr/fityk) is a good choice. It has a bunch of predefined functions, like Voigt, pseudo-Voigt, etc., and many different fitting methods. It is free and open-source and highly extensible (user-defined function, batch processing, etc.) via lua scripts. It also has a really good manual (https://fityk.nieto.pl/fityk-manual.html) and an active group (https://groups.google.com/g/fityk-users).
Another free option is Spectragryph (https://www.effemm2.de/spectragryph/) focused on optics applications.


When an Eb instrument plays the Concert F scale, what note do they start on?

Question: When an Eb instrument plays the Concert F scale, what note do they start on?
plz help?
I was confused on this question and need more clarification because I play a Concert Bb instrument.
Answer: Since you play a Bb instrument, you know that your written C produces the sound of a concert Bb. That is, the instrument sounds one whole step lower than the written pitch. Put another way, the written pitch is a whole step higher than the concert pitch.
Eb instruments are similar. The written C on those instruments produces a concert Eb. Thus, the written note is a minor third lower than the concert pitch -- or the sound is a minor third higher than the instrument's written pitch.
This means that to play a concert F scale, an Eb instrument starts on its written D.
Comment: @Richard that depends on the horn.  For example,  the lower clarinets and saxophones may be written a 6th or a 13th up;  the upper soprano ones down a 3rd
Comment: Technically, the written note is usually a major sixth higher.
Comment: @Richard That's true for woodwinds, but I think the other way for brass. I'll see if I can find something definitive....
Comment: Fair enough; I was assuming, based on the level of the question, only certain instruments.
Answer: An Eb-instrument has its name because when you play a written C there comes out a concert Eb. (Similarly your instrument is a Bb-instrument as you get a Bb when playing a written C.)
Now when the sounding Eb is a minor third above C you have to play an A to get a sounding C and analogous to play a D to  get an F.
As Es-instruments are transposing one 4th plus than Bb instruments they have 1 sharp more in their sheet music part. (= plus one 5th). So you can always derive from your sheet music in Bb adding 1 sharp for Eb- instruments.
E.g. concert tone F:
Bass Bb = G => Bass Eb = D (adding one sharp more)
Circle of 5th!


Can I freely roam on a government owned property, like a police station or a State Bank without permission from anyone?

Question: I wanted to know if the law allows us to freely move or trespass in a government owned property, especially like a police station or State Bank. I know that different countries will have different laws within their own state, but what would a general law say, which most of the countries adhere to?
Comment: If it is trespass, you are not supposed to be there. Plenty of government offices require appropriate ID to be there, including army bases for example.
Comment: I mean which government locations or areas are categorized sensitive and no local can pass from there without proper credentials and permissions, and what doesn't require any? Is there any list, or it depends on country by country basis? If it does, then what law holds in the USA?
Comment: So many downvotes. It was just a simple question. Discouraging.
Answer: Owners of property establish rules of trespass.
This applies when the government owns the land just as it does for private property owners.  Being a citizen of a country does not give you ownership rights on government land.  The government is question can apply multiple rules to multiple pieces of property such as:

Park use only during certain hours of the day
No unauthorized access
Access only for certain uses, such as no camping allowed

Certainly no one thinks that military bases, prisons, etc. should have unrestricted access by the public.  In general, if you're not allowed to be there the government will put up barriers, gates, lock doors, etc., or place signage to indicate limits.  Really not all that different from private property.
Comment: @RameezUlHaq  The 1st Amendment stipulates:  "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."  There is nothing in the Constitution about access to government buildings, though the 1st Amendment may be interpreted to allow users to assemble and speak on government property in some circumstances.
Comment: @RameezUlHaq no, there is no list defining these rules in the Constitution. You are likely to find them in either statutes or administrative policies of government agencies. For example, your local municipal code and/or school board policies are likely to define when and how citizens are permitted to visit local public school buildings. Rules for citizens entering the Pentagon are going to be a combination of Federal statutes along with current military policies/standing orders/etc.
Comment: So basically, if I want to trespass on any government property, I have to know the rules beforehand. Is there a list which defines these rules within the Constitution of USA, and is it accessible for a common citizen to read?
Comment: I don't have any strong prior information about government laws and how do they work. But I heard from some lawyers that the US constitution allows the locals to visit any government building or property freely (unless it is explicitly mentioned by the government itself that it is prohibited to enter such and such government properties without appropriate credentials/permissions). And the local policies established by those people (municipals) who are managing these government properties don't undo our right to visit them since it is backed by the constitution itself. Is that true?
Comment: Makes sense. But I don't understand why all the downvotes, did I ask an extremely awful question.


How to see before there's something to see

Question: How would an organism evolve to ''see''or sense  things with high precision  way before  light hits its eyes or sound reaches their ears, or at least giving the illusion of doing so?
Comment: What you describe with sight is currently believed to be impossible at a physics perspective (and sound may be tricky, though some tricks with a laser microphone might work).  Do you *actually* want this organism to see things before it should, or just to have such good predictive instincts that it maintains the illusion of being able to do this?
Comment: The only route to doing this which has appeared in the [literature](https://en.wikipedia.org/wiki/Thiotimoline) is the Thiotimoline family of compounds, which undergo chemical changes in advance of the physical events that cause them.
Comment: both are good...
Answer: If you want the creature to actually be able to sense before the light or soundwaves reach it, you're in trouble.  There's some severe causality challenges which come with sensing something before it can be sensed.
In particular, if you want it to see something before light hits its eyes, you literally have to break the laws of physics: relativity and Maxwell's equations in particular.  Maxwell's equations specify the speed of light, and relativity shows that we cannot observe any signals faster than light.  It's a law of physics, and has so much evidence behind it that you're basically on your own here, making up a new world.
You could play games with an organism that can generate wormholes, giving it a way to shortcut much of that distance out.  However, this doesn't quite fit what you need.  All you did was give light a shorter path to take; the light still had to reach its eyes before being detected.  Even then, the mathematics of such wormholes put some rather significant limits on where this could go before you have to rewrite the laws of physics.
Hearing something before the sound waves reach the ears is more doable, because sound waves travel so much slower.  We have a device called a laser microphone  which shines a laser on a surface far away to detect vibrations.  Because the laser travels so much faster than sound waves, this technique can be used to be aware of sound vibrations from far away long before the sound vibrations actually reach you.  Evolving such a system would be a bit of a feat, though.  These systems tend to be quite precise.  There are lasers which rely on organic dyes for lasing though, so the chemistry is theoretically reasonable.
A more interesting approach would be giving the illusion of being able to perceive at a distance.  To do this, one of these organisms would need to understand the system which would be emitting light or sound better than you understand it, and be able to sense the precursors to that event.  A very clearcut example can be in war with grenades.  If someone tosses a grenade into a room, you have a few seconds before it emits light and energy... a lot of light and energy (and messy metal bits).  If you hear the noise of a grenade bouncing into your room, you are quite confident that there's about to be a blam, and you take cover.  If you were with someone who was not used to the horrors of war, and whose ears were not tuned to that particular clunking noise, they may be completely unaware that the grenade had entered the room.  Thus, without warning, you drag them behind cover, then the grenade goes off.  To them, it seems like you "saw" the bang happening before it happened.  To you, it was just responding to something you had heard to avoid having to respond to the bigger blam.
Of course, this process can be tricky in the presence of unknown agents who may test the capabilities of this creature.  They may actively seek out the weaknesses in this high sensory ability.  They may not understand that you can hear the clink of a grenade hitting the floor, but they may figure out that wrapping the grenade in a few layers of cloth deadens the sound so that you can't hear it.  Now you're on the same footing as everyone else.
To deal with this, the individual would need to reach out and change the environment in a way which makes it harder to surprise it.  It may send out messenger particles to observe the world from further away and rely the information to you.  Or, more primitively, it might choose a highly forested environment where it's difficult to maneuver without the organism seeing your trail (and potentially manipulating its own trail to try to lead you off).
We see this in human cultures.  Consider the pattern of a series of waystations where one can exchange tired horses for fresh ones on a ride.  This was done in countless cultures (if I remember, the Mongols and Romans both did this, and even in America our Pony Express was built on this model).  By doing this, information of key activities, like troop movements, can be relayed to the capitol long before the troops could actually get that close.
Our nervous system also has several similar systems to give the illusion of prescience.  Our patellar reflex is a reflex which tenses up our legs when we land from a height by sensing the tension in the patellar ligament (this is what the doctor bumps on your knee to check your reflexes).  Upon receiving a shock, this reflex arc will start contracting the quadriceps before the nerve impulses from your feet reach your brain to announce that you have landed.
Half of this reflex is a hardwired monosynaptic link, carefully tuned.  The other half of the reflex is under the control of the brain.  The brain balances these two halves for different circumstances.  The effect is a beautiful handoff from reflex arc to brain-innervated motor activity while your legs are compressing.  Thanks to this beautiful link, it appears that our brain is responding to the fall before it gets word that the fall occurred.
Comment: I've often heard people refer to c as, rather than the speed of light, the speed of causality. If two things (A and B) are distance X apart, then A cannot affect B in less time than it takes for light to travel the distance X between A and B.
Comment: @SGR You can do that, because according to all currently believed physics, the speed of light and the speed of causality are the same thing.  I personally have a preference for "speed of light" because it makes it easier for me to sidestep explaining how entanglement doesn't transmit classical information, but both are valid.
Answer: Quicker processing
Actually sensing something before light hits its eyes would be near impossible. However seeing faster is more plausible than other senses since the speed of light is so much faster than sound and other sources of information about the surroundings
Appearing to be able to see faster would also be difficult since other organisms observing the organism in question would not be able to observe what is happening quickly enough to make that assumption. For example, a person watching another person catch a ball that they hadn't yet seen arriving would rather be seeing the two things happening simultainiously.
As such the organism would to most other creatures to be impossibly quick and agile, but not much more would be apparent.

One way of having an organism that sees faster is to have it process
the information from the eye quicker. Maybe its sight bypasses what
goes for the thalamus in it's brain kinda like the sense of smell do
for us.

This would make it possible for the organism to percieve something quicker than other organisms who process sight differently.
Answer: The simple answer is that it can't be done, but the more complex answer is... well, more complex.
Jump to the next paragraph for more practical based stuff...
There is some dubious research out there which implies that humans begin to react to some things before they could possibly know of the thing they are reacting to. I didn't follow up on this at the time and I take it as very dubious at best. The idea, if I remember right, on how to explain this is something similar to how photons pass through 1 of the 2 slits in the double slit experiment, but doesn't know which one till it has hit, but if you interupted it at the point of going through it would be in one or the other which means that it has to have gotten the information from the aborted future or something like that. I don't buy it, but it's a interesting idea for explaining certain psychic phenomena.
The more realistic approach is that while it is impossible to see something before there is something to see (as far as we know) it is not impossible to be really good at predicting things based on all sorts of sensory inputs. This is partially how martial artists are faster than the normal person. It's not that they are truly faster, but rather they train theselves (indirectly) to react to things that they are seeing that tell what is going to happen next. You see a tightening of a muscle and you know, from experience, that it means a punch from x direction is coming and so you start to react to it, before it has actually happened.
This is also how and why we can sense things aroud us that we can't see. It's because we are noticing and feeling things around us that create a picture of our environment and whats going on even though we aren't able to see them.
Now combine the two along with the basic idea of the greater your knowledge of a situation the more easily you can predict things so that if you have 100% knowledge of all things in the universe you could predict the entire history of the universe from that point forward. What you have then is a way to "see" before there is something to see. Some martial artists display complete mastery of their environment, based mostly on trained instinct, if you were to give someone that trained instinct and with some set of knowledge I don't see why you couldn't produce the illusion of "seeing things before there is something to see"
Comment: I like the practical based portion, especially since we have real live demonstrations of it walking around today, but I am typically wary of suggesting quantum mechanics based solutions unless one is very well versed in what QM is and what QM isn't.You can get into some really bad pseudoscience really quickly and once you go down that path, it's really hard to dig your way out.
Comment: @CortAmmon The experiment from what I remember is that we react to images that we see automatically, especially positive and negative images like those with smiles and such. What was happening is that they would flip an image up and according to where I saw it the brain reacted before the photons of the screen could possibly have reached the person's eyes. If true, it's an interesting phenomena ^.^ if nothing else. And yeah, I'm wary of Quantum mechanics stuff myself, especially since there is a lot of wonky results... It works, but doesn't make sense to us in middle world
Comment: I'd like to see the journal article on it.  It would be interesting to see what they believe they were measuring, and how they went about the experiment.  For perspective, a common measure of reaction to changes like that is the P300 wave, which occurs roughly 300ms after stimulus.  If you're 3 feet away from the screen, the photon traveled that distance in 0.000003ms. Meanwhile, the refresh rate of a screen showing the image is on the order of 10ms.
Answer: The trick is to have senses that aren't strictly light/sound based. We already have such a device for sound waves: a laser microphone can "read" the sound waves striking a surface. Even needing to make the round trip, light is so much faster than sound that a laser microphone can "sense" sounds for a person long before those sounds actually get to that person (and, often, pick up sounds that would never get to that person).
Light, of course, is trickier, given that it's considered the universal speed limit. So, what we have to look at is, what's faster than light? Nothing!
So, how do we cheat?
Wormholes can collapse the distance between two points. If the distance from the viewer's eye to the target was "collapsed" in this manner, then the viewer could experience visual input before anyone else nearby. Depending on frequency and location of use, opening wormholes can have a number of... side effects.
Quantum Entanglement (also known as "spooky action at a distance") has been a popular haven in science fiction for this kind of effect (e.g., many "ansible" technologies). This spooky action has shown strange effects where "entangled" particles can influence each other instantaneously across distance. The problem with this is that entangling particles does not occur at a distance, the information transmitted is not at a macro level in the same manner as other sensory information, and the mechanics and limits of entanglement are not well known so any such solution will likely be subject to "science marches on" in a few years.
Alternative: time travel. If you were able to transmit neural signals backward in time to yourself, you'd be able to pick up "normal" sensory input, feed it to yourself X [units of time] ago, and it would appear that you received that sensory information long before you could have received it.
Answer: Technically, it is possible for things to travel at speeds greater than the speed of light in a medium (e.g. air, water) but lower than the speed of light in vacuum. c, the speed of light in vacuum, is the universe's speed limit, but like everything, light doesn't travel at the same speed everywhere.
See Cherenkov radiation, particularly visible in nuclear pools. Some particles goes faster than the light in water, which gives that distinct blue tint.
To make that work, you'll need three things:

A particle that goes faster than light in your medium (most likely air)
Creatures that emit that particle at that speed, which is definitely non-trivial, but could be explaining by some fashion of sorcery (e.g. every creature in the universe emits FTL radiation just because)
And of course, a creature that can sense those radiations/particles.

Another idea would be tachyons, which is a very hypothetical particle that always travels faster than light in vacuum. Tachyons are most likely non-existant in our world, because they break causality, so your world would have to operate on slightly different physics than ours to allow such a particle (and to allow it doesn't break the universe).


Enable ChangeTracking In Child Objects Using STE

Question: I'm using STE and I want to enable change tracking for an object and its children. What I currently have to do now is something like this.
<code>int id = 1;

using(CustomerEntities context = new CustomerEntities())
{
    CustomerSection custSection = context.CustomerSections.Include("CustomerSections.Customers").SingleOrDefault(p => p.ID == id);

custSection.StartTracking();

    foreach(Customer cust in custSection.Customers)
    {
        cust.StartTracking();
    {

    return custSection;

}
</code>
What I am looking for is a way to automatically enable change tracking for the child objects too, without having to loop through each one and explicitly tell it to start tracking changes.
Thanks in advance for any insight.
Answer: Most probably you are using Self Tracking entities in combination with WCF. Then it's not needed to enable the changetracking manually. this is already done for you. The T4 template that generates the STE's includes a method decorated with the [OnDeserialized] attribute which starts the tracking once entities are deserialized (which occurs normally after reaching the client and converted back into runtime class instances fromout the xml that WCF generated for the transport. See the exact code example:
<code>    [OnDeserialized]
    public void OnDeserializedMethod(StreamingContext context)
    {
        IsDeserializing = false;
        ChangeTracker.ChangeTrackingEnabled = true;
    }
</code>
Search your entities or the T4 template and you will find this soon.


Is it ok to train the model only on the interested part of the data?

Question: Let's say I have a dataset where one feature is 'Car type' : say 'A', 'B' and 'C'.
The test set consists of samples where 'Car type' is always equal to 'A'.
Therefore, should I train my model only on the subset where 'Car type' is 'A' or on the whole training set?
What are the pros and cons of both approaches?
Answer: I think it depends on your understanding of the data set.
How similar are car $A$ with car $B$ and car $C$?
Is car $A$ an electric car and car $B$ and car $C$ running on gas? Is one of them a self driving car and the others are not?
If you are training them together, I think there is an implicit assumption that their behavior is similar and you want to take advantage of that, in particular, perhaps you do not have sufficient data from car $A$ and you are hoping that you can use data from car $B$ and car $C$ to help you.
However, if car $B$ and car $C$ are very distinct and you are trying to predict accident or car failure, adding it to them might not help that much. If the design of cars are very distinct, they might not cause accident or car failure due to the same features.
Answer: If you're meaning to only use the test dataset on that model, doing only the training on the subset of type car 'A' is fine but  the column 'car type' would be obsolete since the values are all the same in that column.
Note : If you put up a Correlation Matrix to see how your feature is affecting your output, it would be zero since column type is not changing which would make it ,as i said, obselete
But, think of your model being put in production, what if it receives a car-type equal to 'C', it will be a new value that it hasn't been trained on, and it would cause a problem to your predictions.
So, better train your model on the whole training dataset rather than peeking at the test dataset to adjust your training ( what you're doing is similar to what is called Data Leakage since you're getting information from the test dataset and altering your training according to what's in your test dataset). Hope this helps! Cheers.


Mean and variance for multivariate truncated normal

Question: Does anyone have a reference for mean and variance of a multivariate normal truncated along a single axis? I.e. $\mathbb{E}[X | x_i > 0]$ and $Var[X | x_i > 0]$, where $X= [x_1,..,x_n] \sim \mathcal{N}(\mu, \Sigma)$.
Comment: https://stats.stackexchange.com/questions/163172 and https://stats.stackexchange.com/questions/385423 answer the question about the mean. The variance question was asked but not answered at https://stats.stackexchange.com/questions/330771.  https://stats.stackexchange.com/questions/504245/ (closed) has a list of links to answers to closely related questions. The full distribution (not just mean and variance) is obtained for an equivalent question (with slightly different formulation) at https://stats.stackexchange.com/questions/444925.
Answer: Tallis explored this problem in 1961, in the publication The Moment Generating Function of the Truncated Multi-normal Distribution, published in the Journal of the Royal Statistical Society.
Later, in 1989, Leppard & Tallis published Evaluation of the mean and covariance of the truncated multinormal in Applied Statistics (38:543–553, 1989).
In 2012, Manjunath & Wilhelm published Moments Calculation For the Doubly Truncated Multivariate Normal Density, which expanded on Tallis's work which focused on single-axis truncation.
If you are in University, you likely have access to these publications via your library's subscription to JSTOR, Wiley, or other databases.
Check the R package tmvtnorm if you are interested in modeling. Link here.
Comment: This is just wonderfully helpful - many thanks for taking the time.


jQuery Mobile freezes while scrolling

Question: While scrolling my jQuery Mobile enabled site on a mobile device (at least iPhone 4 and 5), it almost always freezes for a few seconds, sometimes significantly longer. Usually it eventually just crashes and I have to kill Safari (or Chrome) from memory.
I'm having trouble identifying the cause. I know they state there are issues with transitions, and I tried adding .ui-page { -webkit-backface-visibility: hidden }, but it didn't help.
I'm guessing it might have to do with one or more scripts that are running. My scripts file essentially contains a set of scripts that run for both desktop and mobile, and two more sets that run exclusively for desktops and mobiles respectively. The common set is wrapped in a conditional ready function, $(document).ready for desktop and $(document).on('pageinit) for mobiles.
Also, based on the device, all the scripts are either loaded in the footer for desktops and the head for mobiles. However, the main scripts file is loaded in the footer for both. The scripts wouldn't work on mobiles otherwise.
Not sure if iOS preventing DOM manipulation on scroll is conflicting with something.
I would just link the site, but professional confidentiality and all that.
I'm not asking you to just guess what the cause may be, but I would really appreciate an outline of some fundamental principles of developing with jQuery Mobile to optimize performance.
Answer: According to the documentation (navigate to "scrollstart"), it is expected that DOM manipulation is frozen during scroll in iOS devices, even in iOS 7.

jQuery Mobile freezes while scrolling


How would music sound in different atmospheres?

Question: How different would a musical piece sound in different atmospheres? I assume that sound travels differently in other planets depending on what their atmosphere is made of, affecting the frequencies. Is that assumption correct?
Comment: Have you not heard someone speak after inhaling helium.
Comment: Stringed instruments' pitch depends on length and tension, not the speed of sound, but wind instruments would indeed change pitch.
Comment: This is happening also here on earth, depending on T, P, humidity. Don't know what is exactly changing, if it is pitch or something else. The case mentioned in the comment (He) should instead change the frequency at the source, as for the vibrating stuff has gas adsorbed onto it.
Answer: It depends on a lot of things. In rough order of weirdness:

As mentioned in the question comments, music played live by stringed and percussive instruments would have the same pitches / timbres. But live music by unmodified wind instruments would have wrong pitches because their pitches are determined by the speed of sound in the "wind". Recorded music played by speakers would not be pitch shifted because speakers just reproduce whatever frequencies are played through them.
If the atmosphere is different enough it could have a different acoustic impedance and instruments and speakers could end up sounding quieter or louder because they are able to transfer their vibrations to the atmosphere less or more efficiently.
The atmosphere may also have different acoustic absorption properties than air. This could act like a frequency filter, cutting out high or low frequencies.
If the atmosphere is different enough it could have a non-trivial acoustic dispersion, where different frequencies travel at different speeds through the medium. I'm not sure what effect this would have on the sound you hear.

That's all I can think of for now.


Altering Consensus Rules

Question: How nodes agree to consensus rules? Is it possible for someone to change the consensus rules for his own software and then remain in the previous network? If not, then why?
Answer: If you alter the consensus rules in the software running your node, there are two options:

You apply rules less restrict than before, accepting some transactions that were previously invalid: every block you mine will be displaced by blocks from longer chains mined by the miners that didn't change anything and have more hashpower than you. Because they'll never accept your blocks but you're still accepting theirs.
You apply rules more restrict than before, rejecting some transactions that were previously valid: you are on your own, and will have to mine every single block. Depending on your current hashpower, it could take weeks until the next one. Unless you also change the rules concerning minimum difficulty. But the blocks you mine still will be accepted only by your node.
Answer:
Is it possible for someone to change the consensus rules for his own software and then remain in the previous network?

It is theoretically possible to do this and still remain on the previous network especially if you are imposing an additional restriction (an effective soft fork) rather than a relaxation (an effective hard fork). However I would strongly recommend against doing so on mainnet if any funds with real world monetary value are at stake. The reason for this is even with soft forks you can be forked off the network following a different blockchain if you reject a block due to a transaction in this block not meeting your additional restriction. An example of this was demonstrated prior to the Taproot soft fork when there was one user running a full node who claimed to have been forked off the network for applying the Taproot rules too early when 0xB10C spent an anyone-can-spend Pay-to-Taproot output prior to activation.
When it comes to consensus rules the punishment for diverging from the rules being enforced by the rest of the network is significant. You risk being forked off the network, following a different blockchain and verifying transactions and blocks that aren't representing the actual Bitcoin blockchain (effectively a different currency or asset). So by all means experiment on testnet, signet with different consensus rules but when verifying mainnet transactions and blocks do not do this.

Altering Consensus Rules


Encourage users to add comments to questions. Is it good UX to show a toggle button or is there a better way?

Question:
I want to encourage users to add comments but all the questions show up on one page so having all the comment boxes visible takes up too much vertical space. Is it good UX to show them on clicking a toggle button or is there a better way?
Comment: Yeah I can see how things could get messy if everyone started posting links to "Hey check out my thing!"
Comment: My apologies.

norabora, that's exactly what I wanted to ask. I just couldn't word it correctly.
Comment: Welcome to UX.SE. This question doesn't quite meet the standards of this site as "improve the ux" is not technically a question. Is there a specific goal you want to meet in improving it? e.g. "I want to encourage users to add comments but all the questions show up on one page so having all the comment boxes visible takes up too much vertical space. Is it good UX to show them on clicking a toggle button or is there a better way?" That's an actual question that can be answered. Try adding more information to your question.
Comment: How many questions do you have on the form? And are you soliciting comments for each question? What is the purpose of the comments? It seems weird to ask someone to comment on a simple question about their age.... So it'd be helpful to understand why you want users to invest valuable time filling in comments for every question
Comment: If you really want users to spend time thinking about comments to make, serving them new content (i.e. the next question) directly will cause the content to compete for user attention with the content adding affordance.
Answer: Showing many text areas for every single question could add too much friction.  Showing many toggles is less friction but still more friction than not showing anything at all until required.
I would suggest that you automatically show the comment text area only for the question currently being answered.  Just make sure the place to comment doesn't demand attention and is clearly optional.
Comment: For the case in question, where a select element is being used, this would mean the select opening and the comment box appearing simultaneously. That could be pretty messy.
Comment: Also, in this paradigm, how do I go back to make a comment? I'd have to click the select again to activate the comment box, when I've already made my answer.
Comment: a vertical list has been shown to be the easiest for users to consume - i usually put a field label first line, control second line, validation message (if any) third line and then a small spacer so the labels and controls are easily associated.  in your scenario since the comment is optional it is perfectly fine to place a text area off to the right so it doesn't get in the way but only for the currently active input.  i'll try and make a little demo later but doing it this way will allow users the option to comment on any question without a bunch of repetitive noise
Comment: A comment box to the right? that could work. Especially if any comments made are displayed as text when the user moves to a different item. There would need to be unobtrusive links to edit/add comments for the non-current item.
Answer: Something like this would inform the user that longer answers are welcome, but you would want to do a better job than I have done in the image below; formatting the link and the "optional" tag so that they are obviously related.  As my example stands, some might think that the question is optional, which isn't good.
Answer: You could limit the first type of entry (age for example should be a max 3 digits and maybe a dropdown) keeping a lot of space on the same line. Aside the answer you could have a single line entry field with "add comment" or "elaborate" already written inside it. (Think of Facebook's "what's on your mind".)


What's a word for the act or practice of creating new words?

Question: is there any word in English that refers to the act or practice of creating new words? There are certain disciplines and some particular persons who practices those disciplines which are all the time creating new words, does this action have a name?
Answer: One possible term can be Neologist , which is defined as

a proponent of a new doctrine
an advocate of neology

Neologism is a relatively recent or isolated term, word, or phrase that may be in the process of entering common use, but that has not yet been fully accepted into mainstream language.
Neologisms are often created by combining existing words or by giving words new and unique suffixes or prefixes. They can become popular through memetics, by way of mass media, the Internet, and word of mouth, and often become accepted parts of the language.
Examples include laser (1960) from Light Amplification by Stimulated Emission of Radiation, robotics (1941), agitprop (1930).
Comment: logo means word, right? and neo is new? so Neology could be seen as the act of creating new word aside of "a proponent of a new doctrine"?
Answer: The process of naming something is called nomenclature.
The study of origin of names is etymology.
Answer: COIN (vt):

Invent (a new word or phrase)
'he coined the term 'desktop publishing''

Source: https://en.oxforddictionaries.com/definition/coin


SENT protocol output unit is LSB. What does this mean?

Question: I have read couple of datasheet of devices which uses SENT protocol. They define the output between 193 and 3896. The unit is LSB. I think that this does not mean least significant bit?
Example:
https://www.infineon.com/dgdl/Infineon-KP275-PB-v01_00-EN.pdf?fileId=5546d4625b10283a015b34276c891ce0
Comment: Why do you think that?
Comment: because LSB is not an unit? I don't know
Answer: It does in fact mean LSB or, alternatively, the measurement amount corresponding to 1 LSB.  The specs you're looking at are measurement ranges.  The numbers given are the highest and lowest readings you can expect.  Note that they're 12-bit readings, meaning they have a potential (positive) range of 0 to 4095.  4095 what?  Depends how it's calibrated, but to skirt that quagmire, they call it a LSB and spec those ranges accordingly.  It's kind of like using "percent of full scale" as a unit, but the fact that it's already digitized makes LSB a natural unit.
Comment: 2500 LSB is interpreted as a numeric value of 2500 times the amount and units represented by 1 LSB.  For example, if you have a range of 0-3.3V using 12 bits, 1 LSB means 3.3v/4096, or 0.0008057V.
Comment: I did not understand your explanation. LSB means least significant bit or byte. Yes indeed, the 12-bit data represents a value between 0 and 4095.
Comment: Example: 2500 LSB means 2500 least siginicant bit or byte. That does not make sense..
Answer: At one company we've used internal terms "A/D count" or "A/D tick" for this.  The meaning was the incremental amount of physical value1 which corresponds2 to an increment of 1 in the digital value3.
1 Usually voltage or current, but could be other physical values too.
2 The correspondence is usually linear.
3 From 0xA2 to 0xA3, for example.
Why use arbitrary units such as LSB, A/D counts, ticks instead of using physical units of measurement?  I can see two reasons.

The exact relationship isn't always known.
For example, a relationship between input voltage and the A/D reading depends on the reference voltage.  The authors of the datasheet at the time of writing can't know what the reference voltage will be, and it may also vary dynamically.
The A/D values are always integer, and it often makes sense to stay with integer calculations.  In some embedded controllers, for example, floating point math isn't practical.

I also use "epoch" as a unit of time.  A sampled system usually has a refresh rate, and one epoch is the refresh period.  Why not use normal units of time?  The period may be an odd-looking number when expressed in engineering units of time (how about 17.39ms).  More importantly, I may decide to change the refresh period during the project.
Sometimes I end up with [ticks/epoch] as a unit of measurement.  Why not.


Is 99 percent anhydrous isopropyl alcohol safe for gpu mobo etc?

Question: I normally clean my GPU and motherboard with 91 percent isopropyl alcohol but it leaves an oily looking film even though the bottle says the inactive ingredient is water. I found some MG Chemicals 99 percent anhydrous isopropyl alcohol on amazon but I'm wondering if its safe to use and if it will leave the same film.
Comment: I think you are sweating the irrelevant.  I have even cleaned parts of my pc with gin in a pinch.
Comment: Massive amount of overthinking here. I clean my MacBook's screen with distill water on a clean microfiber cloth. After drying it's pristine and fine and—in fact—the vast majority of computer component cleaning solutions are distilled water. So in the case of 91% isopropyl alcohol the remaining 9% is water of some kind—most likely distilled—and the "film" you see is just residue from the machine itself that won't cause any problems. In many cases when you clean interior components like that you are simply shifting the "dirt" and dust from one place to another.
Comment: 99% will behave pretty much like 91%.  If it's leaving a film, the film is the material you're trying to remove, not the alcohol.  99% might even leave more of a film because it will dissolve more and evaporate faster.
Comment: I should add that I can get the film off if I clean the same spot with qtip and alcohol over and over again. I believe it has something to do with the way the alcohol dries. Sometimes when I clean it, it leaves a film, sometimes it doesn't. I read somewhere that perhaps anhydrous doesn't leave the film. Anyway I guess the 99 percent still has 1 percent distilled water the same as 91 percent. I always thought water caused rust and was conductive.
Comment: @SpaceCowboy Your excessively obsessive cleaning like this will put your system at more risk of failure than no cleaning it at all. I would recommend only cleaning out—or replacing fans—on internal components and not engage in the kind of cleaning you are describing. You are actually creating more problems than it will solve because within a day or two of use, the dust will build up  again.
Answer: In my personal experience, I've found 99% more effective for cleaning CPU thermal paste, especially when complemented with a surface purifier. Arguably if I'd used 91% i'd have experienced the same CPU performance without any additional heat but I'm not going to shell out on some 91% when I have some 99%. Also, make sure you use a lint-free cloth when removing thermal paste.


If mass and energy are same thing, then what is the difference open system and closed system?

Question: In thermodynamics, closed systems are those from which energy can be exchanged and not mass. But Energy and Mass are the same thing, so does that mean a closed system is the same as an open system (a system in which both mass and energy can be exchanged)
Comment: @brucesmitherson - I know what you meant to say, but I'll be a bit pedantic and point out that relativity is also classical physics.
Comment: @GiorgioP I was mistaken, I was completely wrong. I'm going to delete my previous comment. Thanks.
Comment: Similar question: https://physics.stackexchange.com/questions/275187/confusion-with-the-definition-of-an-closed-system
Comment: classically they are different, only in relativity they are the same
Comment: Because you can relate two quantities through an equation does not mean they are the same thing. Especially when this equation is not relevant to 99.9% of earthlings physics
Comment: As long as there are photons how can anything be a closed system?
Answer: The difference between closed and open system exists in Newtonian, Lorentzian, and general-relativistic thermo-mechanics. In all three theories a closed system can be defined as one that has no particle fluxes. Here are some more details.
In Lorentzian and general relativity, conservation of particle number takes upon the role that conservation of mass has in Newtonian mechanics. There are several distinct particle numbers, but baryon number is probably the most important at the interface between Lorentzian and Newtonian physics: it corresponds to the conservation of the different atomic elements in Newtonian thermo-mechanics. See for example

Misner, Thorne, Wheeler: Gravitation, especially chapter 22.

In fact, the conservation of atomic elements – the main principle of stoichiometry – implies the conservation of mass in Newtonian thermomechanics, since each atom is considered to have a constant mass. In chemistry and in the study of mixtures of different materials, atom-number conservation is often used instead of mass conservation. See for example

Astarita: Thermodynamics: An Advanced Textbook for Chemical Engineers, especially chapter 3;
Samohýl, Pekar: The Thermodynamics of Linear Fluids and Fluid Mixtures, especially § 4.2.

In Lorentzian and general relativity energy flux carries inertia, and so it is less meaningful to speak of mass conservation. But particle conservation still holds, and this is why we can speak of particle's velocity, which can be non-collinear with momentum (see Eckart below). So in all three theories we can equivalently define (at low energies at least) a closed system as one which doesn't exchange particles, rather than one that doesn't exchange mass. Note that if we consider osmotic phenomena we can also be more specific and consider systems that are closed with respect to some atom species but not to others.

Regarding transfers of energy, in Lorentzian and general relativity strictly speaking we have to consider transfers of energy-momentum, since energy fluxes carry momentum and vice versa. There is an insightful discussion about this in

Eckart: The thermodynamics of irreversible processes. III. Relativistic theory of the simple fluid.

It is also good to always make clear what we mean by "system". There are two main ways to define a system, both in the Newtonian and Lorentzian case: (1) As a body of particles, which has a world-tube in spacetime, be it Newtonian or Lorentzian; the spatial region occupied by the body is determined by the velocity of the particles. (2) As a region of space, arbitrarily defined, and possibly arbitrarily moving and deforming with respect to some reference system.
In the first sense the system is closed by definition or construction, since we are following a given set of particles. In the Newtonian case this also means that there is no exchange of mass. The first definition does not work very well with systems not made of bosons (atoms), such as radiation. In the second definition the system can be closed or open: there can be particles moving in or out of the region of space considered.
Comment: Unfortunately, the first link ("Gravitation") seems to be broken – "This item is no longer available."
Comment: @Jonas Thank you for pointing out the broken link. Edited with an alternative.
Answer: Ensembles in thermodynamics are defined in terms of quantities that are conserved between the system and the bath. Typically, that means energy $E$ and particle number (mass) $N$. However, this needs to be modified to account for relativity. To say that your system can only gain or lose a particle by exchanging it with the bath is necessarily declaring it to be non-relativistic. Let's go through the three ensembles.

The microcanonical ensemble says that nothing can leave the system. The available microstates are therefore the ones that have the fixed energy $E$. Knowing that each one has probability $e^{-S}$ allows you to derive Boltzmann's formula.
The canonical ensemble says that energy is the only conserved quantity that can leave the system and it does until the system and bath are at the same temperature. Now the probability of a microstate $e^{-S}$ is most usefully expressed using $F = E - TS$ which is the quantity that will be minimized in equilibrium. Note that other things besides energy can leave the system too as long as they are not conserved. Total velocity in the $x$ direction would be an example.
If particle number is a conserved quantity, you can also have the grand canonical ensemble. Now particles are exchanged to get a constant chemical potential and $e^{-S}$ involves the grand potential $\Omega = E - TS - \mu N$.

When you have all three, the systems are described as isolated, closed and open respectively. If you can only define the first two ensembles, I don't know whether it's best to call them (isolated, closed), (isolated, open) or (closed, open). However it's worth noting that several applications, such as electron gases, have a microscopic notion of charge. As this is another conserved quantity, you can therefore get a relativistic analogue of the grand canonical ensemble by simply replacing $N$ with $Q$.
Comment: A perhaps noteworthy extension: Other conserved quantities than electrical charge can be used to define grand canonical ensemble analogues even for neutral, non-number-conserved particles. (e.g. the lepton or fermion number).
Answer: Energy and mass are not the same thing. Although it is justifiably famous, the equation $E=mc^2$ is actually a simplification of the more general equation $$m^2 c^2 = E^2/c^2 - p^2$$ For $p=0$ the general equation simplifies to the famous one, but the relationship between mass and energy also involves momentum. It is not correct to say that they are the same thing. They are equal (in natural units) when $p=0$, but that does not make them the same thing, particularly since often $p\ne 0$.
However, none of the above is relevant to your question about thermodynamic closed systems. A closed system is one that does not exchange matter with the surroundings, as opposed to one that does not exchange mass. Mass is a property of matter, but matter is more than just mass. A thermodynamically closed system could indeed exchange mass with its surroundings without exchanging matter. This would not make it an open system because mass was exchanged, not matter.
Comment: @md2perpe yes, the general formula applies for the box of gas too. As you say $p=0$ so it reduces to the famous formula. You therefore have a mass exchange without a matter exchange in your scenario.
Comment: That formula is easily applicable to a single point particle. But how about a box of gas? When you heat the box of gas, the energy content increases, and so does it's inertia, which we normally call *mass*. The momentum of each gas particle increases (in average at least), but the momentum of the box does not change. In that case I would say that the mass of the box has increase by $\Delta m = \Delta E/c^2.$
Comment: Ditto for a spring that is compressed. There you can't even refer to the momenta of individual particles.
Comment: Matter is only more than just mass when there is a conserved quantity keeping track of it.
Comment: I think that it is often missed when $E^2 - (pc)^2 = (mc^2)^2$ is introduced that when adding energy to a system, both mass and momentum might change. For an elementary particle, mass is constant, but for complex systems it is not, although the mass change is then usually negligable.
Comment: @md2perpe certainly, consider the same box to which heat is added from a frame where it is moving. Then it gains mass as before and in that frame it gains momentum also. I don't know how often such things are missed on first teaching, but certainly it is well know by practitioners


Why is PCA/ML not used frequently in trading?

Question: I'm curious why things like PCA/ML aren't use frequently in trading? Is there an underlying philosophy that prevent this? What I was thinking, was that if PCA worked for making money, then everyone would do it, and so it effectively wouldn't work.
Answer: ML is a very broad term.  Do you mean linear regression?   To you mean random forests?   People use all of these approaches with various degrees of success.   Bloomberg will have a story every few months about a big quant/ML fund starting or being shut down.
PCA specifically is used quite a bit in fixed income to model the underlying characteristics of fixed coupon instruments.  Most of these fixed instruments can explain much of their variance from just the first 2-3 PCA components.
With equities is more challenging to use PCA as the market component is usually the largest PCA weight but then it's the wild west after that with the variance spread over many eigenvectors without a clear real-world explanation.
Comment: Thanks so much. Can you explain what you mean by your last sentence? What exactly is "market component" and what do you mean by its the wild west with variance spread over many eigenvectors?
Comment: Are you familiar with what pcap does?   I'm going to sleep now but I'll try to find some material tomorrow.   Basically pca finds common underliers that explain the movements of the underlying items.   In equities there are too many factors to be useful outside of the first,  which people take as general market exposure.
Comment: Thank you @JoshK
Comment: ML is a promising area in trading/investing, with a lot of interest from firms. My job does not involve ML, but I understand it is not easy to make it work.


Levi Civita and Kronecker Delta

Question: I've been working on some quantum mechanics problems and arrived to this one where I have to deal with subscripts. I got stuck doing this:
I have $\epsilon_{imk}\epsilon_{ikn}=\delta_{mk}\delta_{kn}-\delta_{mn}\delta_{kk}$. But then I went to check and $\delta_{mk}\delta_{kn}-\delta_{mn}\delta_{kk}$ is equal to $\delta_{mn}-3\delta_{mn}$. Why is that so?
Thank you in advance.
Comment: Presumably, they're using Einstein convention i.e. indices appearing twice are summed over. Hence one really has $\sum_{k=1}^3\delta_{kk}=\delta_{11}+\delta_{22}+\delta_{33}=3.$
Answer: Levi Civita symbol $\epsilon_{ikl}$ is defined as it follows
$$\epsilon_{ikl}  = \left\{
\begin{array}{cl}
1 & if\quad i\neq k\neq l\quad and \quad even \quad permutation\\
-1& if\quad i\neq k\neq l\quad and \quad odd\quad permutation\\
0 & otherwise
\end{array}\right.$$
From this definition, let's start with the contraction of $\epsilon_{ijk}$ in its first index:
$$\epsilon_{ikl}\epsilon_{imn}=\delta_{km}\delta_{ln}-\delta_{kn}\delta_{lm}\tag1$$
Where $\delta_{ik}$ is the Kronecker delta (identity matrix), a symmetric isotropic tensor and it is defined as it follows
$$\delta_{ik}  = \left\{
\begin{array}{cl}
1 & if\quad i= k\\
0 & otherwise
\end{array}\right.$$
Contracting $(1)$ once more, $\textit{i.e.}$ multiplying it by $\delta_{km}$ we have
$$\delta_{km}\epsilon_{ikl}\epsilon_{imn}=\epsilon_{ikl}\epsilon_{ikn}=\delta_{km}(\delta_{km}\delta_{ln}-\delta_{kn}\delta_{lm})=\delta_{kk}\delta_{ln}-\delta_{kn}\delta_{kl}=\delta_{kk}\delta_{ln}-\delta_{ln}\tag2$$
Recall that $\delta_{lk} = \delta_{kl}$ due to symmetry properties and $\delta_{km}\delta_{km}=\delta_{kk}=\delta_{mm}$ since they are dummy indices (repeated indices indicated summation over this index).
Now comes the term $\delta_{ii}$, this quantity is a scalar, and represents the trace of the identity matrix in a n-dimensional space, therefore $\delta_{ii}=n$ and finally $(2)$ is written as it follows
$$\epsilon_{ikl}\epsilon_{ikn}=(\delta_{kk}-1)\delta_{ln}=(n-1)\delta_{ln}$$
If one contracts again, the following identity
$$\epsilon_{ikl}\epsilon_{ikl}=n(n-1)$$
In your case $n=3$.
Hope this helps you
Answer: Another approach is to write $$\epsilon_{ijk}=\hat x_i\cdot(\hat x_j\times \hat x_k)$$Then, we have
$$\begin{align}
\epsilon_{imk}\epsilon_{ikn}&=\hat x_i\cdot(\hat x_m\times \hat x_k)x_i\cdot(\hat x_k\times \hat x_n)\\\\
&=(\hat x_m\times \hat x_k)\cdot(\hat x_k\times \hat x_n)\\\\
&=\hat x_m \cdot (\hat x_k\times(\hat x_k\times \hat x_n))\\\\
&=\hat x_m \cdot(\delta_{nk}\hat x_k-\delta_{kk}\hat x_n)\\\\
&=\delta_{nk}\delta_{mk}-3\delta_{mn}
\end{align}$$
Comment: It is really nice!
Comment: @hbr Thank you!  Much appreciative.  -Mark
Comment: Please let me know how I can improve my answer.  I really want to give you the best answer I can.   And Happy Holidays!  -Mark

Levi Civita and Kronecker Delta


When orchestrating, is it ok to double the melody in a middle voice?

Question: If I have, say, a trumpet and a tenor saxophone (among a larger ensemble), and the trumpet is leading the melody in a semi-high register. Can I double it in the middle register, with the saxophone, and still make it sound good? (There is heavy brass accompanying the melody around that range as well.)
Answer: It would probably work ok, but I doubt it would be very effective.

There is heavy brass accompanying the melody around that range as well.

That means right away that the saxophone won't be very audible. That in itself isn't too much of a problem since the trumpet will manage to cut through and make the melody clear, but you need to consider what purpose the saxophone would fulfill, then. Again, doubling a lead voice can absolutely be a useful thing even if the lead completely dominates the doubling instrument. For example

If you double a whole string bass section with a single bassoon, the bassoon will be almost completely inaudible, but it does add a bit of a clearer definition to the notes.
Doubling a blaring brass unisono with piccolo doesn't add any more sound pressure, but does make it a lot more brilliant.
Doubling a melody in the violins with soft horns adds quite some body and warmth, without changing the perceived tibre or taking away from the violins' silkiness.

So what does doubling a trumpet with a lower saxophone accomplish? It could certainly help to counter the tendency of a trumpet to sound thin and harsh, by adding some reedy character below. But I don't see any need for this if there's already a fat carpet of other voices present.
On the flip side, there's actually a few effects that you probably don't want, which might happen if you add the saxophone.

The saxophone will have notes that clash with the brass instruments in the same register. Since both brass and sax have quite similar wide-band overtone spectra, there is little chance for the listener's ears to sort this out again. So it does mean you move towards an indistinct noise-war. This may be fine if you're writing film music for a fighting scene, want to convey the emotions of a football match or something like this, but otherwise I'd think again whether this is really benefitial for your work.
It can be difficult to get a unison between trumpet and sax properly played together, in terms of both intonation, loudness balance and rhythm. (It's not that  precision is inherently more difficult to achieve than with other instrument combinations, it's just that this is one that makes any small discrepancies particular obvious to the listener.) Good players will manage for sure, but it is a risk factor that may just not be worth it.Of course, the ensemble will to some degree wash over any problems here, but this also makes it even more likely that any clashes blend into even more of an indistinct cacophony.
If your goal is to create a really strong, full sound in that passage – this doubling may actually be counterproductive.

A trumpet is on its own then it will be completely clear what its job is, and the player focus on blazing out its part in all the trumpet's battle-cutting glory. If the trumpet needs to share the triumph with the saxophone, this may not work out as well.
Likewise, the brass accompaniment may work better if it doesn't need to give any thought for accommodating the saxophone to share its register. If they have that range for themselves, they can just focus on laying down a heavy wall of sound, making it impenetrable because the trumpet just flies over and no saxophone needs to ram through, and with tight intonation and no distracting melody changing-notes.
Comment: Thanks for your answer! Those benefits aren't too useful for my current situation (that fat carpet is very much present!), and the drawbacks are really spot-on. Guess i should find something else for the saxophonists to do.
Answer: I support and agree with both of the answers by leftaroundabout and Tim.
But I also wanted to offer some additional information, in that I would argue that this kind of doubling will be very effective given the right ensemble size. It's a relatively common procedure when arranging four-part chorales (hymns, etc.) for brass quintets: putting the melody in Trumpet I and Trombone, in octaves, really strengthens that line.
Answer: Yes, it'll sound fine, unless that sax player's original part is just left as an unplayed important part, say the crucial third or seventh of the harmony (so another player ought to play those).
Best way to determine is to hear it played! Nothing wrong with doubling, or playing two instruments an octave apart. Sometimes, though, not constantly.


Does fiat currency disprove labor theory?

Question: From what I understand. LTV predicts that fiat currency, which requires zero labor to produce, should have zero value. Empirically, fiat currency does not have zero value. Would this prove that the labor theory of value is wrong?
Comment: What leads you to believe that LTV applies to currency? Which specific definition of LTV are you using?
Comment: Also "fiat currency does not have zero value" is only true for paper forms' use-value as toilet paper. "Value" ain't "price"
Comment: Since the government demands tax payments in currency, and the consequences of non-payment are a real cost (thrown in jail...), that might somehow be related back to labour hours. (If the government accepted payment-in-kind, taxes could be paid via labour hours.)
Comment: Which LTV? Smith? Ricardo? Marx? Mendel?
Answer: From wikipedia:

Value "in use" is the usefulness of this commodity, its utility. A
  classical paradox often comes up when considering this type of value.
  In the words of Adam Smith:

The word value, it is to be observed, has two different meanings, and
    sometimes expresses the utility of some particular object, and
    sometimes the power of purchasing other goods which the possession of
    that object conveys. The one may be called "value in use"; the other,
    "value in exchange." The things which have the greatest value in use
    have frequently little or no value in exchange; and, on the contrary,
    those which have the greatest value in exchange have frequently little
    or no value in use. Nothing is more useful than water: but it will
    purchase scarce anything; scarce anything can be had in exchange for
    it. A diamond, on the contrary, has scarce any value in use; but a
    very great quantity of other goods may frequently be had in exchange
    for it (Wealth of Nations Book 1, chapter IV).

Value "in exchange" is the relative proportion with which this
  commodity exchanges for another commodity (in other words, its price
  in the case of money). It is relative to labor as explained by Adam
  Smith:

The value of any commodity, [...] to the person who possesses it, and
    who means not to use or consume it himself, but to exchange it for
    other commodities, is equal to the quantity of labour which it enables
    him to purchase or command. Labour, therefore, is the real measure of
    the exchangeable value of all commodities (Wealth of Nations Book 1,
    chapter V).

Value (without qualification) is the labor embodied in a commodity
  under a given structure of production. Marx defined the value of the
  commodity by the third definition. In his terms, value is the
  'socially necessary abstract labor' embodied in a commodity. To David
  Ricardo and other classical economists, this definition serves as a
  measure of "real cost", "absolute value", or a "measure of value"
  invariable under changes in distribution and technology.[4]
Ricardo, other classical economists and Marx began their expositions
  with the assumption that value in exchange was equal to or
  proportional to this labor value. They thought this was a good
  assumption from which to explore the dynamics of development in
  capitalist societies. Other supporters of the labor theory of value
  used the word "value" in the second sense to represent "exchange
  value"

So No, fiat currency has exchange value which is equal to the amount of labor you can purchase with it.
Answer: Fiat currency, the object itself such as a dollar bill, indeed takes labor and capital to be produced. People work with printers to make those baby greenies.
I think your question has a few problems. What is the definition of LTV you're working with, for example? What exactly is value? These are very broad and abstract questions most economists nowadays just don't care about anymore. I guess we're more interested in solving object problems such as poverty and hunger more than in discussing the sex of angels, fortunately.
Answer: Mandel claims Marx treats paper money as a sign of the underlying money commodity:

Paper money, banks notes, are a money sign representing a given quantity of the money-commodity. Starting from the above-mentioned example, a banknote of £1 represents 1/10 ounce of gold. This is an objective 'fact of life', which no government or monetary authority can arbitrarily alter. It follows that any emission of paper money in excess of that given proportion will automatically lead to an increase in the general price level, always other things remaining equal. If £1 suddenly represents only 1/20 ounce of gold, because paper money circulation has doubled without a significant increase in the total labour time spent in the economy, then the price level will tend to double too. The value of 1/10 ounce of gold remains equal to the value of 10 quarters of wheat. But as 1/10 ounce of gold is now represented by £2 in paper banknotes instead of being represented by £1, the price of wheat will move from £1 to £2 for 10 quarters (from two shillings to four shillings a quarter before the introduction of the decimal system).

( https://www.ernestmandel.org/en/works/txt/1990/karlmarx/6.htm )
However, price and value aren't the same:

The price-form, however, is not only compatible with the possibility of a quantitative incongruity between magnitude of value and price, i.e., between the former and its expression in money, but it may also conceal a qualitative inconsistency, so much so, that, although money is nothing but the value-form of commodities, price ceases altogether to express value. Objects that in themselves are no commodities, such as conscience, honour, &c., are capable of being offered for sale by their holders, and of thus acquiring, through their price, the form of commodities. Hence an object may have a price without having value. The price in that case is imaginary, like certain quantities in mathematics. On the other hand, the imaginary price-form may sometimes conceal either a direct or indirect real value-relation; for instance, the price of uncultivated land, which is without value, because no human labour has been incorporated in it. (Capital 1 3:1)
Answer: Wikipedia defines LTV as:

The labor theory of value (LTV) is a theory of value that argues that
  the economic value of a good or service is determined by the total
  amount of "socially necessary labor" required to produce it, rather
  than by the use or pleasure its owner gets from it (demand) and its
  scarcity value (supply). It does not say that the value of a commodity
  is determined by the actual amount of labor contained in it, but the
  average amount needed to produce it. This is called "socially
  necessary labor".

Due to the fact that all currencies roughly (average) cost the same to make yet have wildly different values across countries must mean that LTV's theory that "average amount" of labour needed to produce notes cannot correlate with its value whatsoever, and therefore the value of currency must entirely be subject to supply and demand of currency.
As the same would not be true with global commodities like gold, this is evidence to suggest that fiat currencies do indeed disprove LTV.
However, if one views the cost to produce money/notes (i.e. the cost to central banks from mints) rather than their fiat value, then LTV is not disproven as the 'socially necessary labour' is relatively equal globally and has no connection to currency values.
Note: I may have misunderstood your question but I had a go


Is "dominant in microsoft office" correct?

Question: I'm filling a resume and i want to say that I am good in word,excel and powerpoint.
is saying "dominant in microsoft office" or " dominant in microsoft word and excel" correct?
Comment: Use _proficient_ as suggested. Don't mention the whole of MS Office if you only know your way around those three parts of it; the office suite also contains Outlook, OneNote, Access and more. Also, don't boast about being _very_ good in it unless you actually are able to use the power-user functions such as, _programming_ in the underlying VBa, connecting the different parts of the suite with external (data) sources and creating actual applications based on the existing software... If you can write a letter, create a spreadsheet and make a presentation, _proficient_ is the word :)
Answer: The correct word would be proficient. Dominant would mean that you're more powerful than other people, or that you are influential in its design.
Answer: if you are really excellent, you can use proficient. If not that much, you can use familiar with or aware of
Answer: The both sentences making sense that you are commanding/ruling the application of MS office so better you can prefer "I'm quite capable of using MS office".