Is entropy generation in a process equal to change in entropy of universe?

Question: I read on a source that both quantities are equal ,then why are they specified differently? Can we directly find entropy generation in any process just by calculating the entropy change of universe?
Comment: What do you have in mind for calculating the entropy generation of the universe?  What the source means is that the entropy generation in the process is contributing the the change in entropy of the universe.
Comment: So there was a problem which I was solving in which heat transfer to ice from surroundings was known and we had to find ds. Now ds=dq/t+s gen.But what we found was only ds=dq/t and from that ds of universe.So where does this s gen go here as it should have a value as this process is irreversible.
Comment: Please share your source.
Comment: https://www.quora.com/Is-entropy-generated-always-equal-to-the-entropy-of-the-universe-for-all-systems/answer/Vishal-Anand-6?ch=10&share=fc1302bf&srid=hShEo
Comment: If you can please provide the exact statement of your ice problem, I will provide the interpretation in terms of entropy generation in the system and surroundings, and total for the universe.  But I want to be sure I am answering the precise question you are addressing so that I don't confuse you.
Comment: Problem: 1 kg of water at 273K is brought in contact with a heat reservoir at 373K. When the water has reached 373K, find the entropy change of water,heat reservoir and universe. Also find the entropy generation.
Answer: Whenever they talk about a heat reservoir like this, they are implying that it is an "ideal" reservoir which has an infinite capacity to absorb heat or release heat, with no change in its temperature.  In addition, there is no entropy generated within the reservoir, and any changes in reservoir entropy are equal to Q/T, where Q is the amount of heat received by the reservoir and T is the reservoir temperature.  Furthermore, the temperature at the interface between the reservoir and any system it is brought into contact with is exactly at the reservoir temperature, in this case 373 K.  So, in your problem, during the transient change from the initial to the final state of the system (the liquid water), there can be temperature gradients within the system, with lower temperatures inside the liquid water, but with the highest temperature always at the reservoir boundary.  These temperature gradients are responsible for heat conduction from the reservoir to the liquid water during this irreversible change.  These temperature gradients are responsible for the generation of entropy within the system.
In an irreversible change like this, the first step is to use the first law of thermodynamics to establish the initial and final states of the system and surroundings:
Initial state:
System:  1 kg of liquid water at 273 K
Surroundings:  Infinite reservoir before Q is added
Final state
System:  1 kg of liquid water at 373 K
Surroundings:  Infinite ideal reservoir after Q = 418.6 kJ added
The next step is to totally forget about the actual irreversible process that was responsible for the change from the initial state to the final state, and instead devise an alternate reversible path for bringing about the exact same change to the system.  In doing this, we no longer need to consider that it was the surroundings that was responsible for the change in the system, and can entirely separate the system from the previous surroundings, and use a whole new set of surroundings to bring about the reversible change.  In the case of the system, in order to bring it reversibly from its initial state to its final state, rather than putting it into contact with a single reservoir at a single temperature (which would again lead to an irreversible change), we instead bring it into contact with a series of reservoirs running in temperatures from 273 C to 373 in succession.  In this way, there is never more than an infinitesimal difference in temperature between the system and its surroundings at any location along the path.  This guarantees that the alternate path of the system is reversible.  So in this case, we calculate the entropy change for the system as
$$dS=\frac{dq}{T}=MC\frac{dT}{T}$$which integrates to $$\Delta S_{sys}=MC\ln{(T_f/T_i)}=(1)(4.186)\ln{(373/273)}=1.31\ kJ/K$$
Next we focus on the entropy change for the surroundings.  In this case, since the surroundings is an ideal reservoir and has already experienced a reversible change, we calculate the entropy change simply by dividing the heat that had been received by the reservoir by its constant absolute temperature to determine its entropy change:
$$\Delta S_{res}=-\frac{418.6}{373}=-1.12\ kJ/K$$
So the change in entropy of the universe is the sum or the change in entropy of the system and reservoir:
$$\Delta S_{univ}=\Delta S_{sys}+\Delta S_{res}=1.31-1.12=0.19\ kJ/K$$
So, in summary, during the irreversible process 1.12 kJ/K of entropy is transferred from the surroundings to the system; and 0.19 kJ/K in entropy is generated within the system.  So, the change in entropy of the system is the sum of these, or 1.31 kJ/K.
For a detailed Primer on how to perform calculations of entropy changes and entropy generation in irreversible processes, see the following link:  https://www.physicsforums.com/insights/grandpa-chets-entropy-recipe/


Does "join A with B" yield A-B or B-A?

Question: The title might sound a little silly, but I have this confusion: When someone says, "Join document A with document B", does it mean document A should be first or document B should be first?
Answer: The answer lies in the function word "with", not the word "join".

Join A with B

Would normally be interpreted as meaning to produce "AB".
However we can flip this interpretation by changing "with" to "onto":

Join A onto B

Would normally be interpreted as meaning to produce "BA".
When in doubt, you can use the words "prepend" and "append" to be explicit:

Prepend A to B

Means produce "AB".

Append A to B

Means produce "BA".
Answer: It's ambiguous enough that whoever made the request shouldn't have a problem if you ask for clarification.
As with just about everything in English, it depends a lot on the context.  For instance, the fact that you have listed documents whose names have a natural order (A then B), you would expect that the person wants the first document in the list order to be first.  Moreso, if (s)he want them to be joined out of order (i.e., B then A), this should have been explicitly identified in the request.
If the documents being joined have no order, e.g., join the mango document with the apple document, then you shouldn't go wrong if you join them in the order mentioned—i.e., the mango document first then the apple document.
A different context would be where the two documents contain 'mergeable' information (e.g., lists, database records, etc). In this situation, the join request would result in a document that has items from document B interspersed with items from document A in list order, or record order.
A (slightly) less ambiguous version of the request would be to join document A to document B.  In this case, I would expect the first named document to be added to the end of the other document.  Again, if the documents were named 'A' and 'B' (or 1 and 2, or anything that inferred order), I would still double-check that the person didn't really want 'A' before 'B'.
Comment: Do you get extra points here for nitpicking? The sentence used is just an example. The question is what does "Join mango with apple" mean? I don't like how you pick on "someone" and "A B" that I used. What if this is a sentence written by someone who has died? How do you double-check? This is an English learning community, not a Workplace issues community.
Comment: I'll add a bit about documents where there is no order.  I wasn't picking on 'someone', I just added the single quotes to identify him/her as the person who made the original request.  I don't know what you mean about Workplace issues.   What you have identified as 'nitpicking' is an attempt to show that the answer will differ depending on context and I was trying to show some of these differing contexts.  NO idea what you mean about someone who has died.
Comment: @MingXiu is this version better?
Answer: In the case you mean to join the documents in no particular order, then use this:

Merge documents A and B.

The word "joining" is a  little ambiguous, so you can use words like insert and append if you want a particular order. For example, this:

Insert document B after A.

Does "join A with B" yield A-B or B-A?


How to show a list of processes that are launched upon a login?

Question: There are some processes that are launched upon a login, how to get a list of these processes?
I want to prevent some processes from being launched automatically.
Comment: For the prevention part of your question: [How can I control (start/stop) applications and services that start up after reboot?](http://apple.stackexchange.com/q/66498/8546)
Answer: launchd and the Login Items pane of Accounts preferences are the two places that normally start a process when you log in.
If you don't see the item in System Preferences -> Accounts -> specific account ->  Login Items then you will have to look into launchd.
Basically the LaunchAgents and LaunchDaemons folders in ~/Library
Lastly, if they are not there, then it's a system level launchd task that you might want to use launchctl to show or look in /Library instead of the user level library.
Most people just have to manage the preference pane. Here is a snap of mine showing the Activity Monitor selected and ready to be deleted if I press the – button.
Comment: System Preferences -> Accounts -> specific account -> Login works but how to disable a process?
Comment: If you are the user then just delete from this preferences pane - if for another user then can't if they can run it at another time - if they can run they can choose to run on login
Comment: I'll add a picture to show the command for deleting an item if it's found in the Login Items preference pane.
Comment: Plus: the lesser used, but still valid, *Startup Items* directories. Please see the linked question.
Answer: You need to investigate launchctl(1) because there are a couple of contexts you will need to account for .
The easiest way is to look at the plist files in:
/System/Library/LaunchDaemons # System Context. Faceless. root lives here.
/System/Library/LaunchAgents  # Loginwindow, or Aqua, where you live, context
/Library/LaunchDaemons
/Library/LaunchAgents
~/Library/LaunchDaemons
~/Library/LaunchAgents
In the file you will see the default state of that daemon or agent.  That is a sure way to tell if it is running at boot.
I mention the above degrading, foolish and time consuming method, because it is good to see all the stuff running.  They claim the resources used are low for a loaded yet dormant daemon, but since 95%+ of them are set to RunOnDemand... to me that's running.
Don't actually do that for real though. There is a much easier way.
Remember
When you log in and open Terminal/iTerm, you are in Aqua context.
Loginwindow context is when you see the login window, unsurprisingly, and a ton of things run off that.
If you
sudo zsh  # why not be comfortable?

or some other method to get a root shell, the root user will be in System context, which is the context that all the daemons in /System/Library/LaunchDaemons run in.
I mention all this because the tool provided:
man 1 launchctl

has a verb,
launchctl list

which you might think from the man page, lists all the running services.  You might feel it plausible, to switch to root, to get a higher level view of what runs when you login.
Sadly, each user sees his own context.
launchctl managername

will tell you what it is.
For root, its System.
From my nifty hidden admin user, it's Background, which is the same thing you get by typing
>console

into the username box for login
You can use the verb
launchctl bslist

Which tells you what services are active, for you.  It's different for _spotlight, for the hidden admin, for root, for macports etc.
Answer
The command to see the whole tree, is
sudo launchctl bstree [-j]
whatever you see when you run that after booting is what is running system wide.  For your identity:
launchctl bslist


How can I Enable Google Earth 3D features in QGIS?

Question: I want to ask if there is any plugin or any other way where I can use Google Earth features in QGIS. When I'm saying Google Earth features I mean to be able to see roads, towns, etc and to be able to use the 3D option (Street view tool) I have already installed the OpenLayers Plugin but I did not find something to do it.
Comment: Do you specifically want to see roads and towns from google's servers?
Answer: As far as I know there is no way to use Google Street View in QGIS.
QGIS without Globe does not offer 3D capabilities. Globe is a work in progress and currently does not work on Windows according to Sourcepole (http://sourcepole.ch/the-state-of-qgis-globe).
Answer: Street view is a series of equirectangular still images with geographic reference data, there is nothing to import there that would be usable in QGIS, even if it were possible.
As for the 3D data contained within Google Earth, manipulation, or even data access outside of a Google approved platform is against their terms of service, and not allowed.  Also, QGIS does not [currently] have a 3D viewer to view the data, even if it were allowed.


If I can't find baking soda or baking powder, what should I do?

Question: Suppose I'm somewhere where stores don't seem to stock baking soda or baking powder. Are there other names either of those might be sold under? Or are there things I could substitute?
Related:

How to make baking soda (but apparently you can't really do it)
Substitution for baking soda (but mostly just suggests baking powder)
Making baking powder substitute with baking soda and powdered citric acid (but then you need baking soda)
Comment: Go online, buy a few boxes and have them shipped to you?  Maybe a few boxes at a time, since they should last a fairly long time in storage, to minimize shipping cost per box.
Answer: 1. Chemical leaveners
There are two "oldfashioned" chemical leaveners, both still used today in traditional German and Scandinavian gingerbread recipes:

Potassium carbonate (potash or pearl ash) and
Ammonium bicarbonate (salt of heartshorn)

They do have their own quirks and pitfalls, but if nothing else is available...
If you can get baking soda, mix with cream of tartar to make baking powder.
If your store does not stock it, you pharmacy most likely will carry "sodium hydrogen carbonate" (which is another name for baking soda) either as treatment for heartburn, it's an antacid (because it reacts with acid, neutralzing it and making these nice bubbles, as we know from baking...) or as topical treatment for allergic reactions of the skin (poison ivy and others).
2. Biological leaveners
This boils down to Saccharomyces cerevisiae, aka. baker's yeast or brewer's yeast. Of course you get very different results and have to follow a different procedure. But here are some recipes where they are used somewhat interchangeably, e.g. some types of pancakes or waffles and, obviously, bread (vs. sodabread).
The charming thing about yeast is, that if your are really, really far from a store, you can still get your hands on yeast: Start a sourdough using the yeasts naturally occuring on fruits or the air around you.
Probably not the kind of substitution you had in mind, though.
3. No leaveners
With good technique, you can incorporate a lot of air (because that's what all leaveners are supposed to do) in your baking goods by whipping your eggs well. There are various approaches:

You can whip the whole eggs.
Whip the yolks (with hot water or over a water bath to stabilize them) to Zabaione-like consistency.
Whip the whites and fold into your batter.

You will want to bake these batters right away before the bubbles get a chance to burst. The air will expand during baking and the hardening egg/flour-mixture will trap them in the baked goods. Contrary to many recipes out there there is no real need to bake a pound cake or even sponge cake with baking powder if it's done right.
Other recipes without leavener (or rather with the egg trapping steam generated by a rather high water content) are the members of the popover family (Yorkshire pudding in the UK, Pfitzauf in Swabia, some dutch pancakes) and pâté a choux.
Puff pastry relies on thin layers of butter separating the layers of floury dough and trapping steam between them.
Comment: There are a few traditional christmas cookies where I live (Germany/Swabia) that use ammonium chloride. Smells really funky while baking, but there is no aftertaste in them. Works only for flat cookies, not for cakes, though.
Comment: @Lilienthal http://www.d.umn.edu/~jfitzake/Lectures/DMED/Antiulcer/Treatment/ReducePain/BufferAcid/Comparison.html see the "sodium bicarbonate" part.
Comment: @Lilienthal: Baking soda is an old-fashioned treatment. Especially for long-term use there are modern and better recipes in use today.  In a pinch and if nothing else is available, you can take a small dose of baking soda. The baking soda package here in Germany still lists it's use as antacid or (quote:) "in mild cases of indigestion".
Comment: Having tasted Swedish "salty licorice" with ammonium chloride, I was a bit worried about what the ammonium bicarbonate might taste like. Wikipedia says if the gas can escape, it's totally fine, but if you use it in normal bread or cake you end up with ammonia smell trapped inside :(
Comment: So instead of buying expensive antacid pills, I could just dissolve some baking soda and down that instead? Or would that lead to explosive and presumably quite Pythonesque results?
Answer: For baking, you may be able to find flour with leaveners already mixed in. Look for self-rising or self-raising flour. Note that in the US at least, self-rising flour also has salt added.
Comment: There are also 'biscuit mixes' (eg, 'Bisquick') that are like self-raising flour, but also contain a bit of fat in them.
Answer: depending on the recipe, you could try using beer instead of baking powder.
Answer: Depending on your cookies, cake or funnel cake, you could use self rising flour.
Answer: Baking soda is just sodium bicarbonate, you may find it under that name everywhere. European Union encoded this food additive as E500. Sodium bicarbonate is widely available in any pharmacy or drugstore. pubchem open chemistry database - sodium bicarbonate drugs.com sodium bicarbonate. Anywhere you can buy aspirin, you can but sodium bicarbonate.
Baking powder is baking soda plus an acidic compound, maybe cream of tartar or citric acid, and the addition of cornstarch for stability.
You may substitute baking powder with backing soda and add the acidic agent (buttermilk, yoghourt, lemon juice, vinegar, etc) wikihow - How to Make Substitute Baking Powder
And here are a list of common denominations for sodium bicarbonate:
commonchemistry.org - Sodium Bicarbonate
Comment: The whole point was, what if you can't find it (and that's not just hypothetical - look at the [first related question I linked to](https://cooking.stackexchange.com/questions/54670/how-to-make-baking-soda)). It's *not* everywhere. So I'm not sure I see how this answers the question - you're just saying "if you can't find baking soda or powder, go find baking soda or powder, it's easy."
Comment: Yes, I'm aware - there's even a link in the question about making that kind of substitution. It doesn't help if you're having trouble finding baking soda (whether labeled that or sodium bicarbonate).
Comment: Downvoting is childish. Sodium bicarbonate is so common you can find it anywhare, even in Antartica base.
Comment: @Jefromi in the first related question the OP said: **I eventually found some**. So it wasn't impossible at all even for him.
Comment: Sodium bicarbonate is available everywhere. Any pharmacy will have it, even in the most remote places. Any chemistry place will have it. It's not used just for food purposes.
Comment: And baking powder is just sodium bicarbonate plus acidic agent that may be almost anything, from lemon or lime juice, yoghourt, vinegar,  etc etc.
Comment: If the OP at least said where....


Treat php file as css in Netbeans

Question: So I am working within a PHP framework that puts all of its CSS inside PHP files. In short, the CSS files are called CSS.php even though they do not contain any PHP (just CSS).
I have found that the CSS auto-complete does not like this. Is there anyway to tell netbeans to treat all the code inside these files as CSS without changing the extension?
Comment: Welcome to Stack Overflow and have a nice year!
Comment: Your web server will probably serve your css file with the wrong MIME (supposed to be `text/css`), so just change its extension back to `.css`.
Comment: AFAIK there is not any way to do this ...simple trick would be write in css file and than copy past in php file
Comment: can you mention the name of that php framework?
Answer: You can use a trick as following:
<?php header("Content-type: text/css; charset: UTF-8");?>

Also put whatever other files you need to require before beginning of your css code as:
<?php require 'config.php';?>

Then finally add this line of code which will trick NetBeans to think that you're writing inline css in php file and will work as nothing but a comment line in css file:
/*

Treat php file as css in Netbeans


rolleiflex tlr film rewind lever stuck

Question: shooting today and went into a darker room to change film, forgot to rewind the film before slightly cracking open the camera (half an inch more or less) then realized my mistake and quickly shut it again, but after that the film won't rewind and is stuck at photo 1 for some reason. What might be the issue and what to do?
Comment: Given that one does not rewind 120 film, I'm actually very confused here. Can you post a picture of what you think the Rewind Lever is on the camera? It probably has a very different function than to rewind.
Answer: Unlike 35mm, you don't rewind 120 film. Keep advancing the film until it is fully loaded onto the take-up spool. Then take out the exposed film with the take-up spool. The old spool becomes your new take-up spool.
If you're not sure and just want to play it safe, you can use a dark room or changing bag. If you don't have access to a dark room, you could try crawling under a comforter in a closet in a hallway with no windows at night.
See YouTube: Loading and Unloading 120 Roll Medium Format Film
Comment: https://i.imgflip.com/33ahyq.jpg
Comment: Thank you all. I meant that I could not advance the film with the crank. I opened it in the dark and found the film had been fully loaded onto the take-up spool. After opening and changing the film, the crank worked again... for half a roll. It locked up again this morning in the middle of my shoot. This happened once before, seemed at the time to be the double exposure lever was stuck on, but this morning it definitely was not on but the crank was stuck. After exposing the first shot one more time, the crank became free to move to photo 2. Have not tried to shoot shot 2 again.
Comment: @Charlie Maybe the shutter mechanism didn't fire properly, causing the crank to be "stuck"? When you finish the current roll, consider having the camera mechanics checked.
Answer: Some of the mechanical engineering of (especially later model) Rolleiflex cameras was ingenious, but does need to be handled with a little care. You don't say which model you are using, but I am going to guess it's one of these later models that had a system for "sensing" the film and blocking the film advance from advancing the film too far.
I'm not quite sure exactly what's going on, but I would guess that you have "confused" the camera's film sensing system by closing the back when film has been well advanced inside the camera. (It thinks you have loaded a new film.) Probably the solution here is to simply fire the shutter and then advance the film. You may need to do this a number of times to ensure the film gets wound fully onto the take-up spool. Of course, in order to avoid further exposure of the film, you should do this using the narrowest aperture setting, fastest shutter speed, with lens cap on, in a dark environment (ideally a changing bag).
Additionally, based on the info you provided in your comment to another answer, it does indeed sound like your camera needs to be handled carefully in order for the film advance system to work correctly. When you are advancing the film, don't wind the crank too quickly. Keep an eye on the frame counter and ensure it advances correctly each time. If you wind the crank and the frame counter doesn't advance, then you'll need to fire the shutter (with lens cap on, etc, to avoid double exposure) and wind the crank again.

rolleiflex tlr film rewind lever stuck


When should I add red chili to an omelette?

Question: Is there a proper time to add red chili to an omelette?  How should it be mixed in?
Comment: Paprika, one of several types of powdered red chili, is often pretty tasty in an omelette. You can put it on the finished product too. -makes it look Haute. If you can, grow your own paprika. It's tone better than the stuff that's sat in ship holds and warehouses for years. No worries about red lead contamination then either.
Comment: I assumed you meant chopped chillies in some form, the other answer assumes powder. You may wish to clarify.
Comment: Many would say never.
Answer: Chili powder will never dissolve in eggs. What you're aiming for is a suspension: the chili particles evenly distributed in the eggs. The chili will eventually float to the surface of an egg mix, so the best you can do is mix it properly right before pouring it into the skillet, and hope it sets before the chili separates too much.
Comment: ... or use chilli oil, to whisk into the mix, or fry in (random late-night snack idea ;)
Answer: I often add chopped chilli to an omelette. Fresh or dried (flakes) can simply be stirred into the egg before cooking. The latter is particularly convenient.
Another approach I take is to fry onions/peppers/mushrooms, chilli and/or garlic first, until soft, set them aside and cook the omelette in the same pan (with more oil). Just before folding the omelette in half, put the veg and possibly cheese on top of one side. This is overkill for chillies alone, unless you like a huge quantity.


Can I mount a 3 gang box vertically?

Question: I need to fit 3 switches into a narrow space. Is there any rule against mounting a 3 gang box so that it is taller than it is wide? I will be using two single pole switches and one three way switch.
Comment: ...or you could do a 2-gang box with a single switch and then two switches in the other gang. That would let you have one "normal" switch, which might be nice if you're fumbling around in the dark for a light.
Comment: The problem with triplex switches is that they will almost certainly overload the wiring capacity of a 1-gang box. A single and duplex switch in a two-gang is usually OK depending on the wiring scheme.
Comment: The also do sell 3 switches in a single device "single gang triple switch".
Comment: There are always [other](http://www.westwayelectricsupply.com/tm8113-wcc-decorator-combo-sp-sp-3w-wh-cc.html?gclid=CIKA5eWkksMCFaU7MgodZSsACQ) options as well. Pricey but probably less "unusual" looking.
Comment: Also unusual functioning, since the switches will be sideways...will on be left or right?
Answer: This is absolutely fine. There is no rule or code prohibiting it that I know of.
Comment: I did see the Pass & Seymore combo switch but didn't like the cost and worry about replacing in the future. One of the switches will be used a lot more than the other two. I will probably use three rocker type switches mounted horizontally. One will be a three way circuit so left or right on/off won't matter. The other two I will wire to be on when the left side is pushed in. May look a little strange at first but I don't like the look of separate switches stacked either. The drywall cut would be more difficult too. Thanks to all for the suggestions.
Answer: I have a few 3 Switch Switches and even a few 4 Switch Switches. They make them for 1 or 2 circuit wiring. So you could have a 14/3 going to the box and run 2 switches on one circuit and the 3rd/4th switch on the 2nd circuit.  The Wiring isn't too bad in a normal box. If you are putting in the box, just put in the Deep version.

Can I mount a 3 gang box vertically?


Why do we use the smash product in the category of based topological spaces?

Question: I was telling someone about the smash product and he asked whether it was the categorical product in the category of based spaces and I immediately said yes, but after a moment we realized that that wasn't right.  Rather, the categorical product of $(X,x_0)$ and $(Y,y_0)$ is just $(X\times Y,(x_0,y_0))$.  (It seems like in any concrete category $(\mathcal{C},U)$, if we have a product (does a concrete category always have products?) then it must be that $U(X\times Y)=U(X)\times U(Y)$.  But I couldn't prove it.  I should learn category theory.  Maybe functors commute with products or something.)  Anyways, here's what I'm wondering: is the main reason that we like the smash product just that it gives the right exponential law?  It's easy to see that the product $\times$ I gave above has $F(X\times Y,Z)\not\cong F(X,F(Y,Z))$ just by taking e.g. $X=Y=Z=S^0$.
Comment: Forgetful functors need not preserve products, but they do for nice (i.e. complete) concrete categories which have free objects.
Answer: Two reasons why we want the smash product:

There is a natural homeomorphism $(X\times Y)^+ \cong X^+ \wedge Y^+$ for any spaces $X$ and $Y$. This is one of the places that the smash product naturally arises- you want to describe the compactification of a product in terms of each of the factors, how do you do it? It turns out the smash product is the best way to answer the question. In particular, using slightly more suggestive notation, this gives us the result $S^V \wedge S^W \cong S^{V \oplus W}$ for vector spaces $V$ and $W$... look familiar?
As Jonas said, the smash product is the analog of the tensor product. Recall that the tensor product for $R$-modules is not the categorical product, but it is left adjoint to the Hom functor. This gives it all sorts of nice properties; it's one of the reasons why there is a nice duality between Tor and Ext, and all sorts of other nice stuff. However: I don't think that this analogy is incredibly useful until you move to the stable category... there the smash product is much closer to an honest tensor product, since you're working with an additive category. You can start making sense of what it means to "smash over a ring spectrum" just as one "tensors over a ring" (at least I think you can; you know more about stable stuff than I do.)

As a side note, in response to your parenthetical statement: If you want to know when some functor preserves products or coproducts or some type of limit, it's usually easiest to first check and see if it has an adjoint. See wikipedia on adjoints and (co)continuous functors.
Comment: You definitely can smash over a ring spectrum. Nice answer!
Answer: From nLab:

The smash product is the tensor product in the closed monoidal category of pointed sets. That is,
  $$\operatorname{Fun}_*(A\wedge B,C)\cong \operatorname{Fun}_*(A,\operatorname{Fun}_*(B,C))$$
  Here, $\operatorname{Fun}_*(A,B)$ is the set of basepoint-preserving functions from $A$ to $B$, itself made into a pointed set by taking as basepoint the constant function from all of $A$ to the basepoint in $B$.

There's more at the link.  I must admit that I know nothing about this, but I recommend nLab as a good place to look for the categorical place of mathematical constructions.
Comment: Right, thanks.  nLab is a great resource, but often just a bit above my head since they always define everything so categorically in the first place (as I'm sure they should).  Anyways, my question is more about whether the validity of the exponential law with smash product the *main reason* we like it or whether there's another more primordial justification.
Comment: @Aaron: that is _already_ a pretty primordial justification, in my opinion, at least as primordial as something being a categorical product.
Comment: Right, I guess that's more a philosophical question (albeit one that may have a right answer) than anything else.  In any case, I was just wondering if there are any other really basic reasons why we use the smash product!
Comment: @AaronMazel-Gee Note that this is smash product of pointed sets and not pointed topological spaces. For pointed topological spaces see my question on what assumptions have to be added here https://math.stackexchange.com/q/3934265/476484
Comment: The "that is" is really disingenuous. Saying the smash product is part of a (symmetric) closed monoidal structure carries a lot more content (and is in abstract generality a lot harder to prove) than just $\mathrm{Fun}_\ast(A\wedge B,C)\cong\mathrm{Fun}_\ast(A,\mathrm{Fun}_\ast(B,C))$
Answer: This is pretty much (derived from, I guess) Jonas Meyers answer, but a bit more concrete, and as far as I know why we're interested in it. There is an adjunction $\hom_*(\Sigma X, Y)\cong\hom_*(X,\Omega X)$, where $\Sigma X:=S^1\wedge X$ and $\Omega X:=\hom_*(S^1,X)$. If we define $\pi_n(X):=\pi_0(\Omega^n X)$, or indeed $\pi_n(X):=[S^n,X]_*$, we get $\pi_n(X):=\pi_0(\Omega^n X)\cong[S^0,\Omega^n X]_*\cong[\Sigma^n S^0,X]_*\cong[S^n,X]_*$, which is an interesting relationship.
Answer: This way $\mathbf{hCW_*}$, the pointed homotopy category of CW complexes, becomes a closed symmetric monoidal category with tensor product $\wedge$ and unit $S^0$. This is important, because once we observe that the functor
$$\Sigma^\infty: \mathbf{hCW_*}\to \mathbf{hSp}$$
to the stable homotopy category is lax monoidal, it would follow easily that $\Sigma^\infty$ sends monoids to monoids. In particular, since $S^0$ is obviously a commutative monoid, the sphere spectrum $\mathbb{S}$ is a commutative ring spectrum. In English, the sphere spectrum $\mathbb{S}$ defines a cohomology theory that has a skew-commutative cup product.


when starting ask a question with 'is', should we use capital 'I', lower case 'i' is wrong? Like "is she Portuguese?" or Is she Portuguese?

Question: I know using 'i' character in lower case is wrong, specially when I'm talking about my self, for example : i went to gym yesterday. how about 'is' letter?
can I start my question with lowercase 'i' like is she Portuguese?
Answer: The word that starts a sentence must be capitalized. "Is she Portuguese?"
If it doesn't start the sentence, don't capitalize it. "I wonder if she is Portuguese."
Answer: All sentences, questions and statements start with a capital letter.

Is she Portuguese?
Are they Portuguese

If the word is not the first letter of a sentence it doesn't have a capital. The word "Portuguese" is capitalised because it is an adjective made from a proper noun "Portugal"

When is she arriving?
Answer: The first word of a sentence always has a capital letter. The only time you would not start a question with one is if it isn't the beginning of the sentence.
"I know she lives in Lisbon now, but is she Portuguese or Spanish?"


WCF and System.Configuration namespace

Question: I received an error when an referenced .NET Framework 2.0 assembly tried to execute the following line of code in an IIS hosted WCF service:
Error Message:

exePath must be specified when not
  running inside a stand alone exe.

Source Code:
ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

Has anyone experienced this issue and do they know how to resolve it?
EDIT: My question is, what is the best way to open a configuration file (app.config and web.config) from a WCF service that is backwards compatible with a .NET 2.0 assembly?
Answer: The referenced .NET 2.0 assembly is part of a class library I developed for our enterprise library to handle common taskes.  It was intended to be used in ASP.NET and WinForm applications.
Here is the source code I used to determine which type of configuration file to open:
//Open app.config or web.config file
if (HttpContext.Current != null)
    this.m_ConfigFile = WebConfigurationManager.OpenWebConfiguration("~");
else
    this.m_ConfigFile = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

Answer: I was able to resolve the configuration issue by removing the existing code from my provious answer and replacing it with the following ConfigurationManager implementation:
string MySetting = ConfigurationManager.AppSettings.Get("MyAppSetting");

If works for ASP.NET applications, WinForms applications and WCF Services.  I just over-engineered the initial implementation of my class library 3 years ago....
Answer: It depends on what you're trying to accomplish. On ASP.NET, you'd normally wouldn't use ConfigurationManager for stuff like this, but WebConfigurationManager instead. That said, there's no exact equivalent, since, in reality, the user/roaming/etc stuff that OpenExeConfiguration allows doesn't make sense on a web application.
What do you need it for?

WCF and System.Configuration namespace


saturation point of electrical iron

Question: In my work with electrical iron, I have done a lot of research to try to understand how to determine the quality of it.  Is there a simple way to test for the saturation point?  Some of the methods I read about involved very expensive BH curve tracers, and with some of them you were supposed to use a specific size and shape of a metal sample.  I was hoping to take a stator or rotor and test the iron quality without destroying it.
Comment: It should not be too difficult to detect saturation. I think maybe you could apply a voltage square wave to the winding. The amplitude and frequency of the square wave should be chosen to take the core just to the point of saturation. At saturation, the current will increase dramatically. So you would have a current limit. Under or over current = fail. If the samples do not have windings on them, maybe you could have a test winding that can somehow be placed temporarily (if the shape permits). Maybe you can even design a test winding that can be opened and closed like a snap-on ferrite.
Answer: Saturation in motors is very much influenced by the width of the air gap and the overall geometry of the design. You can run a saturation test and plot a magnetization curve, but it will be difficult to evaluate the quality of the lamination steel. As the motor becomes more fully saturated, the current increases more rapidly as the voltage increases, but there is not a very dramatic or sudden increase.
It might help if you could refine your question. The first part of the question is quite general, but the final sentence seems to describe a very specific situation that is focused on motors. If you are primarily interested in a specific motor problem, it might help to describe it in more detail. Why are you concerned about the quality of the iron rather than the overall performance of the motor? Depending on your situation, you may want to have a very small sample metallurgically analyzed.
Answer: The material saturation field strength (or B-H curve) will be much harder to test in an uncontrolled situation than the saturation current of the winding and core in situ.
If you can remove 1 gram or so of the material, it's possible to use a VSM (Vibrating Sample Magnetometer) to analyze the material characteristics. You would pay someone to do that- the machines are very expensive and fairly needy (requiring cryogens and such like).

saturation point of electrical iron


Is this crack on my seat stay mechanically safe?

Question:
Recently picked up a steel frame and realised there was a crack on one side of the rear triangle, right by the seatpost. Crack seem to be contained towards the outer part of the tube so does not seem to affect wielded joint. Since it's a steel frame, I feel like it's good to go but a buddy thinks otherwise. Anyone experience something similar?  Is it safe or am I doomed for a tragic death ☠? Any help appreciated!
Comment: I would say not a problem.  That seam likely wasn't welded in the first place, just painted over.
Comment: @DanielRHicks that's a brazed frame
Comment: @ArgentiApparatus - True.  It's a lugged frame that would have been brazed.  But that seam in the stay likely was never brazed, just painted.
Comment: I concur with the answers but from bitter experience can attest to the fact that this will only get worse, it's very likely more corrosion that will slowly eat away at the area than a 'crack' per se. You've got time, but if you'd like to retain your paint job, it's best to get this attended to sooner rather than later. I'm staring at a frame in the corner of the room now unridable with a corroded/'cracked' bottom head lug, rode it for about 1.5 years after I first noticed pretty much what you're seeing on yours.
Answer: I think the key question is: how much strength is the elliptical plate brazed over the top of the seat stay adding to the strength of the joint? I'd guess it is adding some strength, as without it there is not much material between the main seat stay tube and the brazed joint. I'd be worried about a crack forming just below the joint which could lead to the stay detaching from the main triangle
However, if one stay detaches it likely won't be a catastrophic failure, because the other stay will still be supporting the rear triangle.
Really you need to consider the risk yourself. If you are a heavy rider who rides the bike hard there's more risk, obviously. At the very least I'd periodically inspect that area to check for any other cracks forming.
Comment: I'd also recommend drilling a tiny hole at the end of the crack to stop propagation.
Comment: A good framebuilder could easily repair that, possibly without much damage to the paintjob.
Comment: Agreed,  at 70kg I'm by no means heavy so I don't see this being too big of a problem.  That said, this would be interesting to see through so I'll be keeping an eye on it for a while and if anything changes I'll report in for science.  Thanks guys!
Comment: It's not an "elliptical plate", it's part of the stay, sliced, then smashed down.
Answer: My guess is that when the frame was made the solder didn't flow into that gap completely and it's been this way since it was new covered over by paint.
If it gets worse over time it can be repaired.
If you don't feel comfortable with it you can get it repaired now.
Argenti is right, a worst case scenario is the seat stay detaching when you need it most.
Even if that happens you have other tubes to hold things together so the rear wheel won't fly off - you'll have time to slow down and get off the bike, so you might have to walk a long ways.
Answer: The crack doesn't seem too bad, but imaging a situation when you descend on high speed and the road is turning, the bike is jolting because the road is a bit rough. So, at this moment the seatstay detaches and it may feel like your tire suddenly went flat and you may feel a loss of stability. If you are an experienced rider you might be able to take such a situation under control quickly if not crash might be inevitable.


Alternative of "unvalidated"

Question: Given something in a state of not having been validated or invalidated, its validness is, as yet, unknown. Can it be said to be unvalidated? If not, what is the proper term?
Comment: "Not validated", plain and simple. No need to invent a confusing single-word term. "Not" has all the negativity of "un-", but none of the ambiguity.
Comment: I agree with @RegDwightΒВB that the ambiguity is best avoided. Good question, though.
Answer: Those who say unvalidated (never having been validated) is "not a word" are simply being prescriptive, outdated, and pedantic. It's been used increasingly over the past century (the chart represents a total of 34,000 instances in print).

I don't see any problem at all with the word, which is clearly distinguishable from invalidated (having been been checked and failed validation). If OP wishes to avoid unfounded allegations of illiteracy though, he might wish to consider unverified as a less contentious alternative.
Comment: Thanks very much for the input. Genuinely very useful and also constructive.
Answer: On the one hand, I'd say that "unvalidated" fills your described need just fine.
On the other hand, in the interest of avoiding potential auditory or visual confusion between "invalidated" and "unvalidated", I'd suggest going with "non-validated" or "not yet validated".
Answer: Either 'not validated' or 'not yet validated' (with a negative and positive connotation, respectively.  There's no reason to make everything into a single word - we not German are speaking.
Answer: Unvalidated meaning "not yet validated" is perfectly OK to use if you ask me, and many people do.

Alternative of "unvalidated"


Remove tasks and index when creating a menu tab from views

Question: I am using views to create a menu tab for my views page and it works fine accept it comes with two unexpected tabs: Tasks and Index, which are showed in the photo below. Is there any way to remove them? Thanks.
Answer: You can achieve this using hook_menu_local_tasks_alter hook.

Alter tabs and actions displayed on the page before they are rendered.

<code>function hide_tabs_menu_local_tasks_alter(&$data) {
    foreach ($data['tabs'][0]['output'] as $key => $value) {
        if ($value['#link']['path'] == "check your path") {
          unset($data['tabs'][0]['output'][$key]);
        }
    }
}
</code>
You can also take a look on Tab Tamer module.

Tab Tamer is an administration utility that provides easy re-ordering,
  hiding, and deactivation of tabs and subtabs. You can also rename tab
  labels.
Tab Tamer makes use of Drupal's drag ordering, but degrades gracefully
  when javascript is disabled.
Tab Tamer utilizes Drupal's cache system to help conserve server
  resources.
Comment: Ok. Thanks for your reply. Could you please explain abit more details of how can I add the hook?
Comment: you can create a custom module or can place it on themes template.php file.
Comment: Read https://www.drupal.org/node/295381
Comment: I have made a module  to hide the Tasks tab but it is not working. This is the code `function remove_tab_menu_local_tasks_alter(&$data) {
    foreach ($data['tabs'][0]['output'] as $key => $value) {
        if ($value['#link']['path'] == "/admin") {
          unset($data['tabs'][0]['output'][$key]);
        }
    }
}`


Oracle:How to determine the size of available shared memory of operating system while setting MEMORY_TARGET parameter for oracle instance?

Question: According to the oracle document:"The size of the shared memory should be at least the greater of MEMORY_MAX_TARGET and MEMORY_TARGET for each Oracle instance on the computer."Oracle document also suggest that we can use the command df –k /dev/shm to get the available shared memory.
I got a little confuse of of shared memory while I am reading the definition of the shmall parameter: This parameter sets the total amount of shared memory pages that can be used system wide , it means that the total amount of shared memory available on the system equals to (shmall*PAGE_SIZE)
So when I am going to set the value of  MEMORY_TARGET, which should I go for, shmall*PAGE_SIZE or  df –k /dev/shm
Answer: You should go for the solution that fulfills your requirements.
Both shmall and /dev/shm are configurable, so first you should to configure them, and after that, you can set MEMORY_TARGET. The default value (on Oracle Linux 7) of shmall is 4 TB, which is irrelevant for most systems. The default size of /dev/shm is 50% of the physical memory.
If you use the default settings, following /dev/shm for sizing can be a viable option, but it may be suboptimal ("Unused memory is wasted memory").
To make things more complicated, MEMORY_TARGET includes PGA, which is not shared memory.
Also, my personal opinion/practice: whenever I can, I use ASMM (sga_target/sga_max_size + pga_aggreate_target) instead of AMM (memory_target/memory_max_size). Especially since hugepages works with ASMM, but not with AMM.


Do other countries have the no-cell-phones-on-planes rule?

Question: The answers to this question list mobile apps that presumably need Internet and are intended for use on small planes. I assume Cessnas and similar planes don't have satellite internet; how do these apps connect? They appear to be mostly used in Europe; do other countries besides the US allow cell phone use on planes?
Answer: To answer the question how do these apps connect?

I assume Cessnas and similar planes don't have satellite internet;

correct, at least not any of the Pipers/Cessnas I've flown but Cessna does make some stuff much larger than a 172 these days...

that presumably need Internet

This is incorrect, in the US and many other countries now where ADSB-Out is required for aircraft mobile apps can plot traffic as long as they connect to an ADSB-In unit. In the Piper I fly there are 2, the Garmin 650 Nav/Comm and a Sentry, both of which I can connect to my IPad and have it display traffic.
I personally use ForeFlight as my electronic flight bag, but there are others like Garmin Pilot all of which have off-line caching of charts/nav-data/information so that you don't need a connection to render anything. Pre-Loading required charts of an area is part of my preflight. ForeFlight offers both internet and ADSB traffic.
Also of note, while I wouldn't rely on it and it could be an issue to actually use your phone in flight, plenty of GA ops occur low enough to simply receive cell service.
Answer: "I assume Cessnas and similar planes don't have satellite internet"
It's not an issue for small single-engine planes anymore. You can get handheld satellite Wi-Fi hotspots (e.g. Iridium GO!) which work when placed on a glareshield or with a suction-cup windshield antenna.


MVC Grid with a datepicker - what is the best way?

Question: I have previously asked how to put a datepicker in a grid, and I did not get a response. I found that the way I did it didn't work, becuse the ID of all the fields in the same column was the same. So when I put in a date, only the first field in a column got updated.
I sent a message asking how to set the ID of a field to prevent this, but no one seemed to know.
So I am now looking at JQ Grid and MVC Contrib grid. I am new to both and I am concerned it will take me some time to figure it out. Which one should I use?
* EDIT *
This is some extra information as to where I am
In my view I have a foreach look and I render a partial view thus;

    <%: Model.T.BankHolidayDescription%>
    <%: Html.EditorFor(model => model.BH.NullableBankHolidayDate)%>
    <%: Html.EditorFor(model => model.BH.BankHolidayComment)%>

I also have an editor template to assign the datepicker to the date field thus;
<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<System.DateTime?>" %>
<%:Html.TextBox("", (Model.HasValue ? Model.Value.ToShortDateString() : string.Empty), new { @class = "datePicker" }) %>

The problem I have is that the ID for every NullableBankHolidayDate field in the grid is the same. So when I select a date, the first field in the column gets updated regardless of the one I choose.
Answer: You can do what you originally require with JQuery and a standard grid. Set a class attribute on your textboxes you want updating then set jquery to add a datepicker  on those classes - rather than on the element id.
For example - assuming you are using JQuery UI datepicker.
<% foreach (var myObject in Model) { %>

        <%= Html.TextBox("MyProperty", myObject.MyProperty, new { @class = "date" }) %>

<% } %>

Comment: Thank you for that. I do something similar for MVC version 2, see new info I have just posted above. Maybe I should try version 1 instead? Seems odd that I have to do that.


What are all the new Tf2 spells and what do they do?

Question: I am wondering what all the tf2 spells from the new Halloween 2013 update do including the fancy book ones exactly do and what they are called officially.
Answer: The fancy book is just a collectible action item (explained here), it does not have different spells from the spellbook magazine.  A list of 2013 magic spells may be found on the tf2 wiki at Magic Spells:
But a quick list is

Fireball (shoots fireballs)
Teleport (throw an energy ball and teleport to where it lands)
SuperJump (Jump very high)
Healing Aura (uber and overheal youself and all allies in a short radius)
Ball O' Bats (Throw out a ball of bats that shoots enemies up into the air and causes bleed)
Pumpkin MIRV (Throw a bomb that produces a ring of explosive pumpkins.  Shoot the pumpkins to make them explode)
Invisibility (Become invisible)
Summon Monoculus (summon a small monoculus to fight for your team)
Summon Skeletons (summon skeletons to fight for your team)(
Tesla Bolt (Fire a wave of electricity that sucks in enemies and deals damage)
Meteor Shower (summon fireballs to the target point, does massive damage to enemies and burns)
Minify (become small and fast)
Comment: I would add that Minify also overheals you. Allows you to psuedo-fly by being able to jump even while in mid air. It also seems to improve the damage output of some classes (soldier) while making others fire more quickly (medic).
Answer: From the wiki page,

Halloween Spells are single use tool items that are used to give various Halloween themed effects to weapons, hats, or classes depending on the spell. They were added in the Spectral Halloween Special, and are enabled and obtainable annually during subsequent Halloween events.
  The Spell Items during the Scream Fortress 2012 event lasted from October 26, 2012 to November 9, 2012. Any spell effects that were applied to any items, along with any unused spells, were erased from players' inventories upon launching Team Fortress 2 after the end of the event. They were enabled and made obtainable again for Scream Fortress 2013, which lasts from October 29, 2013 to November 11, 2013. Halloween Spells can be found inside Haunted Halloween Gifts on Ghost Fort.

So they're special effects added to weapons/hats/classes.


Am I able to ask specific users a question?

Question: If I've read answers from a specific handler and think they seem super knowledgeable in a subject I'm curious about am I then able to PM or ask that specific user a question? Or is this discouraged? Or is there no way to do this?  I looked in the "how to ask a question" tips n didn't see....Thanks!
Comment: I'm happy for you to ping me any time you like to get a second opinion or an answer, if I'm able to. That community is important. That we feel connected.   Also, if you want to provide an answer and want some feedback, I'm happy to help with that also. Please feel free to do the same with mine. :)
Comment: @YvetteColomb Thanks! I will do that!
Answer: All new questions are published for all to see, there is no way to bring a specific question to the attention of a specific user.  Using the correct tags will increase the likelihood that users who specialize in specific areas will see the question.
Keep in mind, everyone here is a volunteer. No one is obligated to answer any question.
If someone is active in our chat room you can get their attention by preceeding their name with '@' for me it would be @JamesJenkins when you start typing @jam... you should get an auto complete option.  If the auto complete does not show, the user will not be notified, as they don't have enough activity in the space to complete the call.
If you have sufficient rep you can add comments below an existing post and include a link to a new question. This is sometimes used (in moderation) for closely related Q&A.


Can I use Laban (a yogurt drink) as a substitute for buttermilk?

Question: I live in the Middle East, and can't find buttermilk for use in baking. We do however, have a plain drinkable, pourable yogurt called Laban , by a brand called Al Marai ( please google to see what it looks like and it's consistency.) Will this drinking yogurt work the same as buttermilk in a recipe?  It is made from cows milk, tastes exactly like plain yogurt but it's a thick liquid in consistency, the same consistency as buttermilk as available in the UK. It is  not as runny as other drinkable yogurts available in the West like actimel or Yakult.
Answer: Probably.
I rarely have buttermilk around, and I most commonly substitute yogurt mixed with water.  The kind of laban you're talking about* would be a similar mixture.
King Arthur Baking Company has published this nice article about buttermilk substitutions on their website:

Here are the most common suggestions [for substitutions]:

1 tablespoon vinegar or lemon juice mixed into 1 cup of milk. Let the milk stand for 10 to 15 minutes, until it thickens very slightly and curdles.
1 3/4 teaspoons cream of tartar mixed with 1 cup of milk. Shake until the cream of tartar dissolves.
Sour cream thinned with milk or water to the consistency of heavy cream.
Plain unsweetened kefir.
Yogurt thinned with milk or water to the consistency of heavy cream.

https://www.kingarthurbaking.com/blog/2019/01/28/how-to-substitute-for-buttermilk
The author of that article tested these substitutes in a number of different recipes and found that thinned yogurt consistently performed the best, or just as well as the other substitutes.
So, if your laban is really just diluted yogurt, it will also probably perform fine.  But it might be worth trying to make diluted yogurt yourself, and testing that against laban.

*A note for other readers: in some places laban (or leben, or liben, or lben - لبن) is "buttermilk", in the traditional sense of the word.  This kind of buttermilk is the liquid that's left over, and strained off, after cultured cream has been churned to make butter.  Confusingly, this butter byproduct, is not what contemporary recipes call for, when they ask for buttermilk.  What contemporary recipes are actually looking for is made from homogenized, pasteurized milk that's been inoculated with some bacteria cultures.  This kind of buttermilk bears some similarity to traditional buttermilk, but it's typically quite a bit thicker.  So, ironically in places where laban means "buttermilk", it may not be a good substitute for buttermilk.
Comment: I always use apple cider vinegar or lemon juice with milk (usually almond milk. I've noticed I don't typically get the proper reaction with oat milk). Thanks for the context on laban @juhasz.
Answer: Yes you definitely can.
Laban (or Lebneh) is close to buttermilk, but a little more runny and often with added salts. We used it as a buttermilk substitute when living abroad.
I have made laban from buttermilk and milk, with a little salt, and a slight blend to get rid of some of the clumps.


An interesting way to explain commutative property of multiplication

Question: Five times three is equal to three times five due to the commutative property of multiplication. Is there any interesting way to explain why this is so?
Comment: five baskets of three oranges is the same amount of oranges as three baskets of five oranges?
Answer:
${}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}{}$
Answer: $5+5+5=15=5\times3$ and $3+3+3+3+3=15=3\times5$
Basically, if $15$ units were the length of a rod/sausage/stick then if you divide it into $5$ pieces of equal length (each of those pieces will be $3$ units long) via $4$ equi-spaced cuts OR into $3$ pieces of equal length (each piece being $5$ units long) via $2$ equi-spaced cuts, it doesn't matter. They'll all add up to give back the original length of $15$ units (obviously).
Answer: Bear with me for a second:
Multiplication commutes in $\mathbb Z$ because it commutes inside $\mathbb R$, and $\mathbb R$ has commutative multiplication because $\mathbb R\times\mathbb R$ is a Pappian plane.
In fact, the commutativity of multiplication in a division ring $D$ is characterized by Pappus's theorem holding in $D\times D$.
To me, this is an interesting reason for the commutativity of $\mathbb Z$ because it's rooted in the actual geometry of the real plane. Sorry if it is too obscure.
There are elementary pictorial or computational demonstrations (indeed, that is how I think the other answers are turning out so far) but I feel like they are not satisfying enough to be interesting, however useful they may be.


Turning off camera while taking a picture?

Question: Does it harm a system camera if you turn it off while it is in the process of taking a picture? For example during a long exposure or while the af needs very long?
Comment: Are you asking about a DSLR, Mirrorless, Point-and-shoot?  The answer is probably "No" in all cases, but there might be some considerations for a certain camera.
Answer: I beg to differ from Jphi1618's comment of "No", but as he/she says, it may depend on which particular camera you have. L. Jordan, if you have an instruction manual for your camera, it may state somewhere in that about such issues.
For several digital cameras I've used and owned, the instruction manuals have specifically stated NOT to turn off camera while it is recording (while the red/orange light is flickering as it writes the data to the memory card). The result being that the data relating to the picture may be corrupted, and may not be readable / viewable when you playback on the screen, or transfer it to a computer.
Comment: Agreed, this is more likely to corrupt the memory card than damaging the electronics.
Comment: It seems you and JPhi disagree only because you are answering different questions.  He answered "no", meaning the *camera* won't get damaged.  You mention that data may be corrupted, which is a possibility with some cameras.  However, that's not what was asked, and not what JPhi responded to.
Answer: It may depend on how sophisticated the camera, you probably should name the camera.  But cameras have lots of smarts now, and my Nikon DSLR manual clearly says "If the camera is switched off while data remain in the buffer, the power will not turn off until all images in the buffer have been recorded.  If the battery is exhausted while images remain in the buffer, the shutter release will be disabled and the images transferred to the memory card."
Answer: No, it is unlikely to harm the camera.  However, harming the picture is a entirely different matter.
Think about it.  The sensor takes power to operate.  Even if the auto-focus and auto-aperture are done and the result frozen, the sensor still needs to be powered.  It then also takes power to run more electronics that transfers the image data from the sensor to the memory when the exposure is complete.  These processes just don't work without power, and turning the camera off almost certainly powers down these sections.
Generally, the more sophisticated the camera, the more it needs to be powered on to perform any of the normal camera functions.  Even many film cameras couldn't be powered down during many types of exposure.  If for no other reason, the shutter was timed and driven electronically.
Some film cameras had a fail-safe mode specifically for when the battery died.  These were generally older models where users were uncomfortable relying on a battery since they'd just come from all-mechanical cameras.  For example, my old Nikon F3T has such a mode.  The shutter is fixed at the X-sync speed of 1/80 s, and you have to set the aperture manually.  There is a special lever to release the shutter, since the normal button doesn't work without power.  I got a nice picture of Morraine Lake in Banff National Park that way once, in 1985.
Nowadays cameras do a lot more for you, which is accomplished by electronics that has to be powered to do all those things.
Comment: Whoever downvoted this, please let us all know what you think is incorrect.


1" threaded forks?

Question: I have an old bike that needs a lot of TLC for it to be useable again. Whilst I am sorting it out, a half hour here and there, I thought I might sort out a few bits that I'd like to improve. Its got a pair of straight leg forks and, on this particular old friend (Since 1992)I want crown headed forks with curved legs. The problem is that the steerer tube needs a 1" fork tube and it needs to be around 16" long! I'd appreciate any ideas where to look for these things. I'm in Englandsville but would be okay to pay shipping for the right parts. Any ideas?
Comment: What do you expect to gain by replacing the fork?  1" threadded is an old standard, you're more likely to find a used part than a new part.  Curved legs (tines?) are generally associated with steel forks, and old alloy ones are to be avoided generally.
Comment: it has steel forks, It's a 1992 Pashley town bike. the reason I want traditional curved forks with a separate crown is, pure and simple, it looks right that way. I am trawling forums and bike shops looking for new or used.
Comment: Many companies still make 1 inch forks.  The trick would likely be finding a 16 inch long tube, as that is ridiculous.  Is that the length of the headtube or are you measuring all the way up to the bars as well?
Comment: yup, that's the length of the actual tube on the frame! It was a large, 24" non compact, frame when my brother bought it. I know it's bigger than I should ride but I am really comfortable with it.
Answer: 16" steerer isn't going to be found on any second hand frame except one just like yours. I think your best bet is to get a welding shop to extend a standard fork. That's basically what I did with my bikes that need long steerers, like this one:

It's not hard, but it helps if the welding person has a rotating jig (or a lathe) to keep things aligned while welding. If you can't do that I'd find a bit of bike tubing that slips over the steerer, then cut the steerer the middle and sleeve that tube over it, making two welded joints rather than trying to find a second, longer steerer and weld that on to the existing one. It's easier to keep it all lined up that way.
Comment: Out of curiosity, what is that bike for?
Comment: Once finished it was a load bike: http://moz.net.nz/photo/2008/06/21-melbun-move/quad-bike-move-06-moz.jpg
Answer: For used parts your best bet is the local ebay or equivalent.  Also search in your location for a bike co-operative.  In my city there are two.
Third option is to buy a complete used bike with the bits you want and then swap parts around.  Ideally you'll end up with a second complete bike out of it.
Buying new steel forks with a 1" threaded steerer is going to be unlikely but not impossible.  Try visiting the oldest, ugliest and most cramped bike shops in your area, and ask nicely.  They may have "something out the back" for nice customers.  If the shop has room for three people to walk side by side in the aisles, its not a real LBS!
Answer: Get one made by a bicycle framebuilder. It's a nice enough bike to warrant it and it's the only way to get one that's really right. Basic replacement 1" threaded forks are readily available, but nothing you'll find is this long.
Framebuilders will also be able to make appropriate choices about either finding a steerer that will work (1" threaded steerers this long aren't common catalog items for them either) or fabricating one that's got the strength and alignment needed for the application.

1" threaded forks?


What is the conical mouthpart of a soldier termite and what does it do?

Question: I'm trying to get a visual understanding of termite anatomy and I'm getting quite confused on the protruding mouthpart area (it looks like a beak) located between the pincers.
What does it do / what is it for? It does not look like a chewing mouthpart.
Further, is it related to the mouthparts of the worker / females termites?
Oddly enough, I found "Conehead" termites with what appears to be a far more profound version of this part (though it might not be) and again I see no purpose for it.
Is there a place on the internet where the breakdown of termites can be found? This would be very useful.

What is between the pincers?
Answer: This is actually the termite's labrum. Its quite big in termites. Does not have value in telling male from female.
Comment: Hi Jules~verne. We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed. Please update. Thanks! :)


Login to a Windows domain from MacBook Air

Question: Is it possible to login to a Windows domain from a MacBook Air over WiFi? I can login fine using a wired connected but couldn't using WiFi. WiFi security is 802.1x.
Answer: Yeah, it should be possible.  Your problem may be in the wifi network you are using.  Some companies don't allow people to authenticate to their intranets from the wifi networks they expose, they keep them separated for security.  You have to check with your administrator if the wifi network you are using has access to the domain authenticator.
Comment: You have a valid point. If unauthenticated WiFi users are able to "access" the domain controllers, it's a credible security threat.
Answer: First check that you can ping your domain server.  Depending on your router or where you are authenticating to, the wireless network and the wired network aren't on the same subnet. Or in the case of many workplaces, the domain controllers aren't even reachable through the wireless network. . .
Comment: I forgot to mention that to be able to connect to the wireless network, the user needs to feed in his domain credentials via 802.1x


How will locking behave in .net?

Question: abstract class Foo
{
    private List<Object> container;
    private bool update;

    Foo Foo()
    {
        container = new List<object>();
        update = false;
    }

    public abstract Bar CreateBar();

    public void BeginUpdate()
    {
        if (!update)
        {
            Thread update_thread = new Thread(new ThreadStart(Update));
            update_thread.Start();
        }
    }

    private void Update()
    {
        update = true;
        while (update)
        {
            lock (container)
            {
                if (...)
                    container.Add(this.CreateBar());
                else
                    container.Remove(...);
            }

            Thread.Sleep(1337);
        }
    }

    public void EndUpdate()
    {
        update = false;
    }

    public List<Object> Objects
    {
        get
        {
            lock (container)
            {
                return this.container;
            }
        }
    }
}

When something outside of Foo calls the Foo's Object accessor like,
List<Objects> objects = foo_instance.Objects;
foreach (Object o in objects)
{
    Thread.Sleep(31173);
}

How will the locking occur? Will the thread running Update() have to wait until the above foreach is done processing objects list? I would like that these two would work simultaneously, is the only solution to make a deep copy of objects?
Answer: Several problems with this code:

You do not start the thread
You can have a race-condition (might not be applicable to your program) where multiple threads call BeginUpdate, both sees that update is false, and both start a thread, now you have two threads running, possibly interfering with each other, since you have a field member with the shared data
What is the point of locking in the property? You don't need it. Note that the container you return from the property will at times be in a state of flux due to the inner update. This means that outside code that calls the property will have to lock the container itself before accessing its contents. You do not need a lock to return the container reference though.
Race condition if you call EndUpdate and then BeginUpdate right after each other, the old thread might not have had a chance to exit yet

I'd say that before you start worrying about what to lock and when, you should fix the code so that it doesn't have lots of other thread-related problems.
Comment: Thanks, good insight. Had to give you a verbal cherry since I cannot vote. ;>
Answer: Your code does not do what you think it does. This method
public List<Object> Objects
{
    get
    {
        lock (container)
        {
            return this.container;
        }
    }
}

Does not hold the lock after it has returned the value. So your loop is not locked.
You cannot return the container instance from the clas
Answer: You can think of lock scope similar to function scope.  Doing a lock inside of your accessor method will only lock between the braces, once the value is returned the lock will be released.  You'll need to do the locking outside of the class (in the caller) to get the desired effect.
So both the loop and the thread will be able to access objects at the same time.  That's bad, because if your thread changes objects during the loop, the loop will throw an exception because the collection was modified.
Answer: krosenvald is correct, the lock on the Objects accessor is released as soon as the property returns the pointer to the container object...
In you code
List<Objects> objects = foo_instance.Objects;
foreach (Object o in objects)
{
    Thread.Sleep(31173);
}

The lock only lasts for the first line... where the reference variable "objects" is being populated...  There's really no need to lock anything for that line since no memory is being modified by fetching the pointer...
Comment: Would there be a possible access violation if object 'o' was used and accessed inside the foreach?
Comment: Well, what do you mean by "access violation"?  There certainly will not be any lock contention, as the target of the lock will have released the locj by the time the foreach begins...

How will locking behave in .net?


Re-Saving neccessary?

Question: I have switched the field of the SEOmatic plugin to translateable. All the SEO Titles are taken from the entry title. After changing to translateable I can see the translated fields in the SEO Title field but I need to save the entry again to see that on the website. Until then, the title is just in one language. Why is that? Is there any way to automate that, since I have a hundreds of entries and I dont want to do that manually.
Comment: You can loop through all entries and re-save them in php. There are plenty examples how to save entries in the web. https://craftcms.stackexchange.com/questions/5385/plugin-controller-save-entry fetch them all like you are used to in twig and loop through them. I don't see any issues
Answer: I'm not entirely sure why you need to resave all the entries but I do know how you can do it quickly and easily. I'd recommend using the Walk plugin by Michael Rog to do this.
The plugin is pretty well-documented in the repository README, but I'll outline the steps here for you as well:

Download the plugin folder, drop it in /craft/plugins, and install the plugin in the Craft CP.
Add the yiic file from the repository into the base folder of your Craft install (next to the craft folder).
Open your terminal, cd to your Craft install, and run the following:
php yiic walk entries --section=blog --limit=null entries.save

Obviously replace blog with the name of your section.

Hopefully that does the trick for you! Let me know if you have any questions...
Comment: Thanks, that sounds like a quick and easy solution. Any idea why I get this error?

CDbConnection failed to open the DB connection: SQLSTATE[HY000] [2002] No such file or directory
in /Applications/MAMP/htdocs/website/craft/app/etc/behaviors/AppBehavior.php (876)
in /Applications/MAMP/htdocs/website/craft/app/etc/console/ConsoleApp.php (216)
in /Applications/MAMP/htdocs/website/craft/app/etc/behaviors/AppBehavior.php (80)

already tried everything meanting here: https://craftcms.stackexchange.com/questions/7127/using-yiic-for-plugin-migration
Comment: @Jan yeah it sounds like it's having a hard time finding the db credentials and thereby establishing a connection. Where are you setting these - in a .env file, in your Craft config, index.php, etc?
Comment: unix_socket=/Applications/MAMP/tmp/mysql/mysql.sock did the trick for me. Check https://stackoverflow.com/questions/41852050/yii-console-command-cant-connect-to-database?rq=1

But the plugin didnt help yet, since I have to actually change something in the entry field so SEOmatic updates the SEO title field...

Re-Saving neccessary?


FPV system for ground vehicle

Question: Is there a VR goggle system with remote control made for ground vehicles? Drones have a clear line of sight, so I would imagine the same system would barely work on ground? I need up to 200 metres of distance - there would be a few obstacles. Is there such a system? I would need basic control inputs - analog up/down and left/right. And, most importantly, clear video signal in VR. Price is not an issue.
Comment: Well, any radio system will struggle in dense areas... what kinds of obstacles do you have in mind for the video link to deal with?
Comment: trees, cars, etc. it wouldn't be something through buildings - mainly in open air with possibility to go around the corner
Answer: Lower frequency = better penetration*
A 900 or 433MHz control link (DragonLink is the only plug-and-play 433 I know of off-hand) will penetrate quite well, and has impressive range with direct line of sight.
1200MHz (1.2GHz) video systems are available. Standard receiver modules for goggles are also available so that these can be drop-in solutions for existing equipment.
Ground vehicles have the advantage of (hopefully) maintaining a consistent orientation, so antenna placement is much easier. Everything can be done vertically polarized, and at lower frequencies, multipath interference is less of an issue. Linear directional antennas can have very high gains if desired.
*MIMO systems may be able to catch non-Fresnel reflection paths and work with them, however at the expense of latency and with greater processing. Analog video systems are not MIMO, but some digital systems such as DJI likely are. In this case higher frequencies can actually be advantageous as there is more likely a reflected path.

FPV system for ground vehicle


How to display list of images in ListView in android?

Question: I am new to android. I want to display the list of images using the ListView. The images which are displayed are decided at runtime according to server response. and also i want to embedd some text on this image(like match scoring chip). the number of images are not fix. Can anybody help me here?
Answer: I would read the 6 parts to this series. It will show you how to create your own custom listview rows to accomplish what you are asking for:
http://www.androidguys.com/2008/07/14/fancy-listviews-part-one/
Comment: Since that blog post series is a bit old, I have a more current edition of the same material available in a PDF: http://commonsware.com/Android/excerpt.pdf


Loose Moen single handle faucet

Question:
Can't seem to figure out how to tighten this. The whole thing has become loose up top. It's in a new (3 yrs) house
Answer: Moen has an actual socket to tighten the nut in question. I have also been able to tighten them with a small, 6", adjustable wrench. The Moen tool can usually be picked up at your home store or a plumbing supply store. here's what the tool looks like:

You could also use a deep socket if you are a tool collector. Good luck
Comment: A common basin wrench should also work to tighten it a little.  Their size makes it a pain to fully install one of these faucets, but you can fuss with it to get a few turns on that nut.
Comment: A "crow's foot" wrench works well in the absence of the original tool.
Comment: Sorry for the delayed response folks.

I was very tempted to pick up a "crows foot" set. I had never seen those before. But after reading the comment about a "basin wrench", I suddenly remembered that a long time ago a guy gave me one of those and it's been tucked away in an old toolbox for literally decades. I drug it out and what do you know, it finally got put to good use!! And just like jPhi1618 said, it was tricky to get positioned in that tight space, but I was able to get a grip and a few turns, enough to get that thing tightened. So we're good to go.

Thanks for all the replies!!

Loose Moen single handle faucet


sudo: /var/lib/sudo/navneet writable by non-owner (040777), should be mode 0700

Question: This error occurs whenever I try to work with sudo. I changed the permissions of /var/ folder to 777 and I think this causes the error. Please help me get back a functional sudo and /var.
Comment: try making it 555 ie. no write permission, only read and execute
Comment: Duplicate of: http://askubuntu.com/questions/234583/how-can-i-reset-the-permissions-of-var
Comment: @saji89 I'm not sure these should be considered duplicates. This is specifically asking about a problem with one file, is focused on getting `sudo` working again, and is primarily concerned with *how* to make the change; [that](http://askubuntu.com/questions/234583/how-can-i-reset-the-permissions-of-var) (while it's certainly relevant to the OP here) is about how to fix permissions for *all* the files in `/var` and doesn't concern itself much with *how* the changes will be made once it's been determined *what* they are.
Answer: You have a really big problem, but not really for the reasons stated here.
Changing the permissions on all of /var will make it likely you will not get them all back correctly, because you will not know what permissions every file should have. You may have problems later. Depending on the circumstances, your problems might be security-related.
Therefore, you may wish to consider reinstalling Ubuntu. Alternatively, you can try to get the permissions from the files in another, similar, unbroken system. The permissions are usually the same. Usually. A more serious problem is that it's likely your system has some files in /var that are not present on the other one, so probably not all the permissions will be fixed.
Performing administrative tasks on a desktop system without a working sudo is usually trivially easy, though.
Changing the permissions back when you know what they should be is easy, and rarely requires booting into recovery mode or from a live CD. This is because, while it's not widely known, desktop versions of Ubuntu (and most other GNU/Linux operating systems these days) have two ways set up to perform administrative tasks:

sudo, which will not work because it requires the permissions in /var to be correct.
PolicyKit, which tends to be more tolerant of wrong permissions and usually still works.

While we tend to think of sudo as the way you perform actions as root on Ubuntu, actually PolicyKit is the way most, though not all, graphical utilities become root. (It has been this way for some years now.)
Actually, running a graphical program manually with PolicyKit is sometimes a significant undertaking as graphical applications must have special configuration files for PolicyKit to be willing to run them. But terminal applications don't -- it's just as easy to run a text-based command with PolicyKit as with sudo.
To do it, type pkexec where you'd otherwise type sudo. (They don't take all the same command-line options, but the most common syntax for sudo is sudo command, and pkexec works perfectly in its place.)
So, because sudo is broken, you cannot run:
sudo chmod 0755 /mnt/var/lib/sudo
sudo chmod 0700 /mnt/var/lib/sudo/<username>

But you can run:
pkexec chmod 0755 /mnt/var/lib/sudo
pkexec chmod 0700 /mnt/var/lib/sudo/<username>

That's a good start, and it will probably make sudo work again. (It's not going to fix all the other files in /var, though.)
Related (but, in most cases, not identical) situations where pkexec is helpful:
‣ How to modify an invalid /etc/sudoers file? It throws an error and it's not allowing me to edit again to fix it
‣ accidently blocked access to sudoers.d whilst trying to change ushare config
‣ 'sudo' not working after changing the permissions of '/usr' directory
‣ How to fix sudo after "chmod -R 777 /usr/bin"?, sudo error, is mode 0777, should be 0440,
           How to repair "sudo: /etc/sudoers is mode 0640, should be 0440?"
‣ Installing ZFS changed my sudoers file
‣ Password not working for sudo ("Authentication failure")
‣ Why does nothing work after I randomly changed some file permissions?
‣ changed /etc permission in oneiric (ubuntu11.10) by using "sudo chmod 665 /etc" cant use sudo now
‣ How do I run specific sudo commands without a password? (just if something goes wrong)
‣ Can't write /etc/sudoers from Ubuntu live CD (just if something goes wrong)
Answer: You have a really big problem in your hands.  First of all, in order to get you sudo working again, you will need to change the permissions of the /var/lib/sudo folder and the file navneet inside of it.
But, in order to do it, you will need root access.  If you happen to have changed the root password, then you will only need to su - and change the permissions as below:
$ chmod 0755 /var/lib/sudo
$ chmod 0700 /var/lib/sudo/navneet

And you are good to go.  But, if you haven't changed your root password, you will need to obtain root access by other means. On a standard Ubuntu install you can do this by booting into recovery mode. This is done by rebooting and hitting the shift key after the BIOS screen disappears. It is advisable to hit it repeatedly, but slowly. If you succeed the GRUB Menu will  come up and you can chose the second option (marked recovery mode). From the next menu you should chose root shell. This will bring you to a root prompt. On 12.04 you will need to make the hard drive writable to make any changes. The command for this is mount -o,remount,rw /. It make take several attempts to bring the GRUB menu up.
Alternatively you may use a boot CD.I suggest you to use the Gentoo minimal installation CD, as it is small in size and will get the job done, there are also several specialist recovery CD's available. A standard install CD will often  work if you choose to live boot rather than install.  Boot your computer through the CD, and mount your partition to /mnt/ (mount /dev/sda1 /mnt), for example.  Then you may change the permissions like this:
chmod 0755 /mnt/var/lib/sudo
chmod 0700 /mnt/var/lib/sudo/navneet

It is best to use this to backup your data and then do get a fresh install. Since other applications may stop working because of wrong permissions, and there could be other consequences that compromise the security of your machine.
Answer: I had a similar error, but was still actually able to use sudo (It displayed the error message, and it did what I told it to do after that.), so I fixed it with:
sudo chmod -R 0700 /var/lib/sudo

(I was running Ubuntu 14.04)


Exposed to toxic chemical, but little symptoms - workers compensation or personal injury claim?

Question: I've been exposed to a toxic chemical 5 days a week for 2+ years at work because I was improperly trained and told it was safe to use without gloves. I was trained directly by the owner of the business if that matters. Besides a burning sensation on my hands after work and coughing because of inhaling small amount of the chemical a few different incidents I have no noticeable injury. Am I eligible for  workers compensation or a personal injury claim?
Comment: There should have been a MSDS for you to examine for all chemicals you would come into contact with at  your employer.  I believe its actually required by law that they have them:  https://en.wikipedia.org/wiki/Safety_data_sheet  You should file an OSHA complaint as well as a complaint with your state OSHA equivalent.
Comment: It may depend on what the chemical was. If it was something that would only cause immediate injury (such as bleach) then that is one thing, but if it can have hidden long-term effects then that is quite another. I'm guessing that compensation will depend on the severity of the injury, so a potential latent injury would be important.
Answer: Probably yes. In general, if you are an employee, and you get hurt doing your job (as it seems you did), your employer is liable.
In most states, employers are required to carry workers compensation policies that pay your injury claim. But even if your employer doesn't have workers' comp, they are still liable, and they still have to pay.
The theory here is that when do what your employer says, they become responsible for keeping you safe. If they fail to do so, then in the eyes of the law, they may be liable to you. That doesn't necessarily mean they did anything evil or obviously irresponsible. It just means they failed in their duty to protect you.
If you were an independent contractor (and not an employee), you may not be eligible for workers' comp. But if you were doing what your boss told you to do (in legalese, if you were acting as their "agent"), you probably still have a claim.
You can always file a claim yourself, but many people in your situation choose to hire a lawyer to help them through the process. Hiring a lawyer can help you avoid certain mistakes, and can help ensure you get the best settlement possible. The downside is that it can cost some money--though often much less than they can help you obtain.
Comment: Negligence, even implied, is not part of the concept of worker's compensation which is based on strict liability principles.
Comment: True. I did not say it was, but I can see how my answer could be misread as implying that. Updating.
Answer: Usually, a worker's compensation statute imposes strict liability without regard to fault on the employer for all injuries and occupational diseases arising from the job, in exchange to limiting the compensation awarded to that available in the worker's compensation regime. Usually employers are required to buy insurance for this liability, but if they do not, they are still responsible. Generally, however, you are not allowed to bring a personal injury suit against an employer and co-workers.
The strict liability without regard to fault aspect is very broad. For example, it covers injuries suffered by a convenience store employee during an armed robbery, and slip and fall injuries suffered while employees horse around in the break room.
While worker's compensation statutes bar personal injury lawsuits against the employer and co-workers, they do not generally bar personally injury lawsuits against third parties.
For example, if you were injured driving a car in connection with your job, you would have both a worker's compensation claim and a claim against the "at fault" driver.
Absent facts that you do not describe in your question, you would generally be barred from bringing a personal injury lawsuit in the circumstances you describe, but would have a worker's compensation claim.
Unfortunately, the remedy for worker's compensation is frequently quite grudging. You are usually entitled to lost wages and medical expenses related to the injury or disease, and to compensation for any temporary or permanent disability you suffer, generally rated with a duration (in the case of temporary disability) and a percentage of impairment (which in your case might be in the single digits). There is generally no compensation for "pain and suffering" or "emotional distress" or other forms of non-economic damages. And, to get any remedy at all, a doctor will have to agree that your symptoms are caused by your employment.
Answer: You are eligible for workers' compensation if you file a claim and it's approved.  You should contact your state's workers' compensation department if you need information on filing a claim.
You can always file a claim against any other insurance you or your employer may have, and it would processed and paid in accordance with the insurance policy.
If you are inadequately compensated by these programs you can generally sue someone – i.e., make a claim in court.  But only a lawyer in your jurisdiction could properly evaluate your specific case to advise you as to what theory and law you might sue under.
Answer: Workers' compensation claims are generally limited to things like medical bills from your injury, replacement of part of your income while you recover, vocational retraining costs, partial compensation for permanent injuries, or survivor's benefits to your family. Unfortunately, for claims including pain and suffering or other non-economic damages, you would not be able to bring a claim in the workers' compensation system. Additionally, if you were a 1099 contractor, you will not be able to file through the workers' compensation system.
If you think that your boss, coworkers, or supervisor did this to you intentionally, you might be able to bring a third-party negligence claim of some sort outside of the system. This would be a normal type of court case. However, depending on what this chemical actually is, it could be carcinogenic and might be trouble in the future. You should definitely keep an eye on it and stop exposing yourself to it at work.
I would consider talking to a personal injury attorney about a negligence lawsuit. Under negligence laws, your boss owes you a duty of care and breached that duty. If you're not sure that you have a case, try looking at this checklist. It sounds like your boss was acting in violation of some sort of law, and if it doesn't fall under workers' compensation, it has to fall under something. Who lets their employees handle chemicals without proper protection? At the very least, OSHA should come in and investigate.


I'm having trouble getting Derkeethus out of the cave

Question: When I lead Derkeethus to the exit of the cave and then wak out he doesnt come out with me. Is there a different way to get him out? Or am I doing it wrong? (Console)
Answer: There is poor routing for followers in that cave. You have to take a few steps at a time, make sure he's following you. Have him very close to you when you finally open the door. He has a really hard time crossing bridges and water. Remember there is the upper and lower exit from that cave, so you can try both.


What's the difference between a tail number and a Manufacturer's Serial Number?

Question: What's the difference between a tail number and a Manufacturer's Serial Number (MSN)? How and when are they generated?
Answer: The tail number is the civil registration, and the manufacturer serial number (MSN) is a build number used by the manufacturer.
It is similar to the licence plate on your car, and the vehicle identification number applied by the builder of the car.

What’s the difference between a tail number and a Manufacturer's Serial Number?


Run windows 2008 but keep display running

Question: I am running an EC2 instance of Windows Server 2008 and need to capture video output of some running programs. My problem is that when I end the remote desktop session, the video is no longer sent in a way that allows for it to be captured by a running screen-capture process. Is there any way to force Windows to send video in a way that can be captured by software even if no RDP session is active?
Comment: Why is that a problem? Can you explain what it is that you're actually trying to do?
Comment: Try disconnecting from the session instead of logging off.
Comment: @MDMarra I know this is an old question, but Windows won't render anything to the screen without an RDP session. It might be more accurate to say there is no screen to render to.
Answer: There is a way, but you will have to use a different remote desktop than RDP. When a remote desktop connection is disconnected, the display that the programs use ceases to exist. Programs can still update, but there's no display for the OS to use to render the output. Therefore, there's nothing for a capture program to capture. The solution to this problem is to either (1) never log out of your RDP session or (2) use the console which always has a defined display. It's a similar problem to what this user is experiencing, although his program requires the use of the console. I don't know what screen capture program you are using.
In any case, since it's not possible to connect to the console via RDP on Server 2008, you will need to use a different remote desktop tool such as VNC. I tested with RealVNC on Server 2008 R2 and RealVNC Viewer on Windows 7 Pro and was able to successfully connect to the Server 2008 console. You might want to try those programs and see if you have success with your screen capture.
If you are performing automated testing, as the user in the question linked above was doing, you can set some VNC clients to "view only" and then use psexec to start your testing process. A simple batch file may be able to easily start your testing on one or more servers.
Comment: I need to actually get visual feedback from the instance itself when I'm not connected.
Comment: Yeah the only option I was able to find was using a VNC to make the display render again(btw I can RDP into Server 2008 just fine). I was hoping to find a modified display driver or something to bypass the need to connect to all the instances when they boot up.
Comment: Why do you need to connect to the instances when they boot up? Are you starting a script or program when you do that? Can or is it automated (a batch file)? Is your goal to have something run in the background on the servers without any intervention or login by you?
Comment: @KellyElton I know this is an old question but have you found any solution for this?
Comment: @ChiragMS I didn't find anything that hasn't been mentioned in this post unfortunately.