Can science prove statements to be true?

Question: I know that mathematics can prove certain statements to be true, which we call theorems. But what about science? Can science prove statements to be true? Note, just because a statement can't be proven to be true by science does not mean it is not true. I am merely asking whether science can prove the truth of statements. Of course, this depends on what we mean by "prove". Also, have any philosophers written about this issue?
Comment: What do you make of the sentence 'The mass of the Moon is less than the mass of the Earth'? Or how about 'The Thames is shorter than the Nile'?
Comment: Mathematics does not prove statements to be true, only that some statements are equivalent to or imply some others. At best you can establish that A implies B. Then if you determine that A is true, B is also true
Comment: @MarcoOcram Was this intended to be addressed to my answer?
Comment: This question hinges on a polysemy around *Prove*.  See analogous polysemy around [law](https://philosophy.stackexchange.com/a/64737/37256).
Comment: YES. Subject to revision. Anyone else like to give an answer? I'm not sure that this is the place for Nonduality.
Answer: Yes, certain types of non-mathematical statements can be proven, depending on what meaning of 'prove' you have in mind.
Mathematics is a formal system, so that proof is essentially a matter of demonstrating that a statement is consistent with the axioms and rules of deduction. In an analogous way you can prove the correctness of other statements which are related to systems of rules. For example, you can prove the validity of a move in chess by referring to the rules of the game; you can prove that a person with a given income is obliged to pay a given amount of tax by referring to the prevailing tax code.
Other types of accepted proofs are associated with evidence of various sorts. You can proof the validity of the statement 'it is raining' by looking out of your window. You can check the truth of the statement 'Bertrand Russell won the Nobel Prize for Humorous Fiction' by consulting accepted authorities. Science can play a role in providing that kind of evidence to support a decision about whether a give statement is true.
What science cannot do is to prove unrestricted general statements, since its method of verification typically relies on physical evidence, so the validity only stretches as far as the evidence does. For example, we cannot prove that the speed of light always has a given value- all we can say is that in the various tests that have been performed, its speed has been found to have a given value, subject to some degree of experimental error.
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Answer: A common form of mathematical proof is 'showing it cannot be otherwise' (ie proof by contradiction - if you can show that the negation of your statement leads to contradiction then it is impossible that it be false)
If you mean by 'proof' something like the above then scientific statements notoriously can't be proven since there's no way of showing from our epistemic perspective that they must necessarily be true. And many practising scientists explicitly reject the literal truth of their theory anyhow - on one popular view it's rational to disbelieve your best theory on the grounds that you're confident that a better, different one is around the corner.
Two dissenting voices:first, Descartes really did believe that scientific knowledge could we achieved with infallible certainty (because God would be a deceiver if humans could investigate to the best of their powers and still get it wrong). Second, you could argue that 'proven' just means 'adequately tested' - which I guess is now the sense in which it's used in makeup ads that use the phrase 'clinically proven'...
Comment: As for apodictic scientific knowledge, I think Kant and Hegel would be much better examples. Descartes only has thw category of knowledge "by divine light", there's not much to get from him about scientific knowledge specifically imho.
Comment: Apart from the fact that Descartes specifically presents his project as one of getting knowledge in "natural philosophy" (what we now think of as science) on a footing of certainty. And (as a point of order) Descartes doesn't only believe in knowledge by divine light/intuition - empirical knowledge is also possible once God's existence is proved. Last two meditations make that clear.
Answer: No. This is the analytical path:

Reason is the set of thinking rules, which is not formal. When I reason, I follow certain thinking rules, which are not formal (e.g. written). Consider here that sometimes I make mistakes. Those are not yet logical, but rational mistakes.
Logic is the formal expression of rational rules. That is, this is a set of written and logically consistent rules (notice that the consistency of logic is provided by... logic; that's why many philosophers, like Russell, sustained that logic is circular, tautological). Here, there are no logic mistakes (ideally). Logical rules are consistent, rational rules are not necessarily logically consistent, but they tend to be, in a person that has survived. When we speak of logic, we mean essentially propositional logic and all forms of logic that emerge from it (e.g. predicate logic, fuzzy logic).
Logic organizes judgements around in two groups: truth and falsehood. Truth is very complex to define, however, it can be considered that rationally (metaphysically), truth is just a group of consistent judgements, and empirically (physically), truth is the set of rules of experience (obtained by means of the senses) that are consistent with the logical truth.
Mathematics is just a metaphysical extension of logic. Truth in mathematics exists due to Logic.
Science is a set of empirical truths. Notice that two groups of judgements have been defined: physical (empirical) and metaphysical (rational). Science addresses ONLY empirical truths. Metaphysical truth (e.g. God exists) is not scientifically verifiable.

Now, for the question:

Can science prove statements to be true?

The question is quite ambiguous and vague. However:

If an statement is purely rational, yes, provided that the sufficient logic (e.g. the elementary objects like truth, falsehood, and the necessary rules, like Modus Tollens, etc.) and dependent axiomatic systems (e.g. mathematical axioms) contain all required elements to reach the judgement (e.g. 7+5=12 is true).
If an statement only contains rational and empirical elements, yes, provided that the sufficient logic (e.g. propositional logic), dependent axiomatic systems (e.g. Laws of Thermodynamics) and empirical facts contain all required elements (e.g. chemical reactions tend to minimize the free energy of the system.).
If an statement contains metaphysical elements which are not part of logic (e.g. aesthetics), no. Science cannot address metaphysical facts (e.g. "La Gioconda transmits feelings of sadness" is true...).
Answer: When we say that something is "proven," we mean that it conforms to certain rules of objectivity. Logic has one set of rules that help us determine the validity of an argument. Mathematics has another set of rules, but it is built off of logic and can't contradict it.  Natural science, in turn, has a set of rules that includes a contingent element that is based on experience, but must conform to logic and mathematics which supply objectivity.  This is why we can say that the proposition, "the Earth is round," is both contingently and objectively true.
In logic, we say that the premises are sound based on the evidence and the form used to reach the conclusion is valid based on logic. Therefore, "proven ".
Answer: Logical Positivism was premised on the idea that both science and logic verify claims.  Karl Popper pointed out that science can never verify anything, it can only fail to falsify it. There is virtually no dispute that science cannot do verifications. Popper put falsification at the core of science, where it remains.
Note that Popper considered all observations and facts to be tentative, not certain. "Facts" are the hypotheses that we have enough confidence in to use to anchor and test other hypotheses.
However, multiple critics of Popper's falsification attacked the principle that science can do falsification either.  Kuhn looked at the history of science and showed that paradigm shifts were at best only loosely related, and more commonly basically unrelated to newly discovered facts that could falsify a theory.  Paul Feyerabend pointed out the radical difference in methods of science in different fields and different maturities of a field. Willard Quine, in the Quine-Duhem thesis, pointed out that all theories are always underdetermined by evidence, so no certain falsifications are ever possible either.  Extending Quine-Duhem to the hypotheses we take as facts -- none of theme are certain either, so we cannot have certainty even of our data.  Poppers strict approach to falsification may be an aspiration, but it is not actually achievable.
Popper admitted this himself in his later years, and proposed an alternative method of doing science, which relied upon cental and ancillary hypotheses, rather than falsification. One could compare rival collections of hypotheses by the degree of predictability they offer.  The more potential states of the world that a central plus ancillary collection that matches our data predicts could not happen, the better the hypothesis. This is a rephrasing of Occam's Razor.
Imre Lakatos proposed a more structured variant on this alternative from Popper, where a family of core plus ancillary assumptions is called a Research Programme.  Research Programmes are used in an active field, where ther are always a lot of open questions.  The more useful advances that a Research Programme enables, the more "progressive" it is, while the more unresolved questions it has to carry as unresolved, and the more ad hoc ancillary hypotheses it must take on to deal with surprizing observations, the more "regressive" a Programme is.  There can be multiple rival Research Programmes being pursued in a field, and their adoption or abandonment is based on the judgement of their users on how progressive or regressive they are.
Popper and his ally Lakatos, with these alternatives, conceded that science can do neither verification nor falsification, although it DOES still do testing.  The interpretation of test results though, is a far more judgment based process than simple verification or falsification implies.
So, no.  The consensus of philosophers of science is that Science can neither verify a truth nor achieve an absolute falsification.
Comment: wow indeed. a true disincentive for me putting in my one cent's worth!
Comment: Wow.  A short summary of the decades of 20th century debate on this very question, plus names of the leading philosophers and movements involved got DOWNVOTED!!   Wow.  Tough crowd.
Comment: Very true!
Comment: That's a misunderstanding of the Duhem-Quine thesis. The thesis says that any statement of a theory can be held to be true in light of any evidence because it doesn't have any observational consequences by itself. This doesn't mean that a whole theory is never falsifiable - a theory has observational consequences and can be falsified. The only challenge that the Duhem-Quine thesis poses for falsificationism is that: (a) a theory understood as something that you can find in textbooks has to be supplied by auxilliary assumptions (about instruments etc.) to produce observational consequences.
Comment: @Dcleve (b) an amendment to an already well-established theory cannot be falsified independently. We falsify the whole theory (in conjunction with the amendment). Because our knowledge of biology, chemistry etc. depends on physics, this means that potentially discoveries in any science can have an effect on physics and other fundamental natural sciences. Popper thought it's more granular.
Comment: I upvoted, but please make it more precise.
Comment: @abcga -- I think you are a bit off on Quine Duhem, but you are correct, my text benefitted from some elaboration.  I spelled out what "facts" are, why Popper recanted on falsification, and what the alternatives to it are.
Comment: +1 I've upvoted. DQ talks about holistic requirements about theory including auxiliary theories and tests, but I don't think it rejects confirmation of theories so much as confirmation of statements. That's what confirmation holism angles with. Theories are not statements but are interlocking webs of belief and statement which must be held while individual planks are swapped out.
Answer: If prior to the invention of mobile phones, there was a statement such that recordable images of the natural world can be stored and displayed for future observation.
That proposition or statement can be proved as a product of science by reading this as my expression of an answer to your question.
Answer: If by the word "prove" you mean show to be true or good, then the answer is no for science and maths. Any argument has some assumptions and some rules for going from assumptions to results. The assumptions of the argument might be wrong and the rules might also be wrong, so they can't prove the conclusion to be true. This was pointed out by Karl Popper in "Realism and the Aim of Science", especially Chapter I and in "On the Sources of Knowledge and of Ignorance" in "Conjectures and Refutations" and also
https://www.thebritishacademy.ac.uk/documents/4924/46p039.pdf
Knowledge, including scientific and mathematical knowledge, is created by guessing solutions to problems and criticising those solutions until only one is left and it has no known problems. Popper called this critical rationalism (CR).
The Duhem-Quine problem isn't an issue for CR. If an experimental results clashes with a theory then the result might be wrong, or might have been misinterpreted or whatever. The way to handle that is to come up with a guess about the solution to the problem that has independently testable consequences, e.g. - if you think your telescope's optics are distorting your view of a planet and making it look like a theory might be wrong, then it should also distort your view of other objects.
Answer: Depends on what you mean by 'prove'. There are a number of good responses here. Dcleve brought up the main contention between logical empiricism and positivism and Karl Popper and his beliefs about falsification in his theory of critical rationalism. The positivists said yes, and Popper said no. After Quine, you have an array of positions about what science can do and what it is in practice, such as the views of Imre Lakatos. What can be said with certainty is that Popper is usually understood to have undermined confirmationism and verificationism so if science proves claims, it does so at best tentatively.
The key turning point philosophically in your question is what is meant by proof. Proof means many things to many people. In order to understand what you mean by proof, you would have to explain your views on evidentialism. From WP:

Evidentialism is a thesis in epistemology which states that one is justified to believe something if and only if that person has evidence which supports said belief.1 Evidentialism is, therefore, a thesis about which beliefs are justified and which are not.

Let us say, then, that generally science produces claims that are far more reliable and useful than pseudoscience or religion in the domain of discourse about the physical world. You can't pray rockets into space, and certainly astrology offers no guidance. Physics on the other hand can land a VCR on the moon with amazing accuracy. In this sense, science is successful because it relies heavily on empirical evidence which has a partner in philosophy called the correspondence theory of truth. Science tends to produce claims that are far more difficult to falsify and are far more robust in creating change in the world, a topic that is understood by philosophy of mind as direction of fit.
So for all intents and purposes, in general conversation, science proves statements about empirical matters to be true with the caveat that further information might show science has made a mistake. Thus science generally proves claims true about the physical world, but no claim is beyond revision, improvement, or falsification. This is consistent with the epistemological position called fallibilism (IEP).
Answer: The truthfulness of the mathematical proofs depends on the underlying axioms. For example, Euclidean geometry is based on the following 5 axioms:

A straight line may be drawn between any two points.
Any terminated straight line may be extended indefinitely.
A circle may be drawn with any given point as center and any given radius.
All right angles are equal.
For any given point not on a given line, there is exactly one line through the point that does not intersect the given line.

The above axioms are assumed to be true -- and all subsequent proofs are conditional on the axioms holding true.
The natural sciences have similar foundations. They are based on certain assumptions about our reality -- and all scientific proofs are, therefore, conditional on those assumptions holding true. These are the assumptions as I see it:

There is only one objective reality that we all share and belong to. That is, we assume that we are not dreaming it all up, that we weren't spawn into existence 10 seconds ago with our memories implanted, etc.
This reality is deterministic. Things do not happen at random, but every event was caused by some past event. The laws of nature prescribe how exactly causes create their effects. Those laws are immutable.

To sum it up: scientific proofs are possible but they depend on the above assumptions.
Answer: Imagine you have a Lego castle you built, and you want to know if it's strong enough to hold a toy dragon. Science can't give you an absolute "yes" or "no" answer, like a magic spell. Instead, it's like testing the castle with different weights:
Small Lego people: If even tiny figures make the towers wobble, it's a warning sign! This is like scientific experiments that find weaknesses in an idea.
Bigger Lego creatures: If a medium-sized griffin makes the walls crack, it's more evidence the castle might not be strong enough. More experiments add to the picture.
The big dragon: If the dragon sits on the castle and it STANDS STRONG, that's like a lot of scientific evidence supporting the idea. But what if a bigger dragon comes along? Science is always open to new tests.
So, instead of a final "true" or "false," science gives us confidence levels based on evidence, like your castle tests. The more tests it passes, the stronger the idea.


"has gone by" or "has gone bye?"

Question: Is it correct to say, "so much time has gone by", or should "by" be replaced with "bye?"
What are some other things someone can say with "by" at the end?
Answer: I presume you are talking about the preposition at the end on the sentence?
In response I quote Winston Churchill:

This is the sort of pedantry, up with
  which I will not put.

But seriously, the idea that prepositions cannot occur at the end of a sentence comes straight from an era when grammarians tried to force English into Latin grammar (where you really cannot put a preposition at the end of a sentence).
The "rule" is completely archaic.

"That is more than the factor it was multiplied by."
"This is the priest we were married by."
"This is the rule I live by."

Are all perfectly acceptable, and whilst, "I live by this rule," is more regular it is no more correct. Certainly "This is the rule by which I live," is more inelegant and has worse flow than the version with the "unlawful" sentence-ending preposition.
Answer: "So much time has gone by" is correct. This would be understood to mean "so much time has elapsed" or "so much time has passed".
"So much time has gone bye" would be (at best) a sort of pun, based on the personification of the elapsed time. (picture time as a person, waving good-bye as it goes past. You would say that time has gone 'bye!'). You would have to write this using quotes around the word "bye" to make it clear that it was meant to be a play on words, and not a typo.
Some other phrases which can end in "by":

The train has gone by
Why don't you come by (informal ...for a visit? is implied)
These things are hard to come by
Comment: "So much thyme has gone 'bye'." Would mean, I suppose, that Winter has come and that the harvest of this herb has concluded.
Comment: Ha! Yes, I suppose it would. `:)`
Comment: @trideceth12 - Ha-ha-ha! Beautiful! Thanks for that! :-)

"has gone by" or "has gone bye?"


E3D-v6 hotend on MK8 extruder

Question: I have an MK8Makerbot(?) extruder on my HICTOP branded printer.
The problem with the E3D hotend is that the heatbreak is shorter and doesn't protrude through the top of the heatsink. Therefore I can't mount it to the motor mount.

Any ideas?
Comment: This looks like an Anet A8. Replace the whole x carriage.
Comment: @James Trotter I figured as much but was looking for a 2nd opinion. If you change your comment to answer, I will be more than happy to accept it. Now all I got to do is to print a mount for the inductive sensor since the nozzle in no longer in the same position due to the shorter heatbreak. DOH! Should of saw that coming. I need new glasses!!
Comment: What exactly is your question? You obviously need to make some adapter or redesign the extruder. Do you want somebody to give you the model file? Have you tried searching on model repositories (e.g. thingiverse, youmagine, etc...)?
Comment: http://www.thingiverse.com/thing:1798616/#comments Like this one? but am confused as to how he got it to mount onto the motor mount
Comment: I don't understand what you are trying to do with the heatbreak? have you removed the heatsink from the E3D and are just trying to put the heatbreak/block straight in to the bottom of MK8 extruder? You will lose _all_ benefits of the E3D by doing this, as the heatsink/fan assembly of the V6 is what makes it perform so great. The Anet A8's stock cooling at the "cold end" is terrible, I cant see you getting any benefit without the full heatsink from E3D. I've written up a full answer that hopefully explains what you need to do, i can get the files i used if you need them
Answer: For reference, I have the same printer and am speaking from my experiences.
You have two routes you can take with this, but both are effectively the same result - you need to replace the X carriage.
If you want to re-use your existing extruder components you can pull the MK8 extruder off the X carriage and use it as the extruder to drive a bowden configuration, then all you need is a length of PTFE tube and the couplers between the E3d and the MK8 to hold the tube. This is probably the best solution as it takes a lot of weight off of the X-carriage resulting in significantly better print quality, the only downside is that printing with flexible filaments is a lot more difficult with a bowden configuration, if you intended to do a lot of that.
The other option (and the one I took) is to print an entire new x-carriage/extruder assembly. Because the Anet A8 is based off the Prusa and the Z/X carriage assemblies are basically the same as the original Prusa I3 you can just take any design for the Prusa and fit it onto the Anet, I did this with a gregs wade extruder & E3D hotend mount I found on thingiverse.
I didnt look too hard, but if you are adament on wanting to keep the MK8 extruder on the X-carriage and couple it direct-driven to the V6, you can probably find some x-carriage that lines the two up for this purpose (or you could even design one yourself if you are interested in doing so). I didn't look in to this route myself, so cannot give much guidance.
Comment: I use and would recommend the following parts: Integrated extruder solution with easy to mount accessory block and good locking of the hot end: https://www.thingiverse.com/thing:1383913 Simple but prolific and reliable X carriage: https://www.thingiverse.com/thing:184933

E3D-v6 hotend on MK8 extruder


Play embedded f4v file in flash?

Question: Hi is it possible to play an embedded f4v file in flash?
Answer: Yes, there's a wizard for adding a video to a swf you find it under File|Import|Import Video.... But it's not really recomendable. You often get out of sync video/audio. Plus the swf file will be huge.
Answer: You can pull the file with swfObject's parameter.  It also depends on what type of player you're using.
Answer: Sorry, but the answer is a big fat no. I know, I know – it's awful.
You cannot feed embedded movie or aac data into the Flash Player's "native" media player. It can only play these files from a NetStream. You can play embeeded mp3s (and some other lossless formats) but you want video, I see.
I'ma see if I can do some hijacking and let you know if I succeed, but I'm not hopeful.
From this article about this stunningly bizzare oversight...

flash.media.Video requires a flash.net.NetStream. This means you cannot load embedded videos..."

Play embedded f4v file in flash?


Marketing Cloud FTP --> Automatic Delete Functionality

Question: Is there a way to setup a rule so that your Marketing Cloud FTP will delete a file older than a certain date?
Comment: Talk to support. They can usually adjust your retention period on the FTP. I believe by default it should be at 30 days.
Answer: The custom retention periods will no longer be applicable for the customer's accounts.
Marketing Cloud will retain your files on Marketing Cloud FTP for at least 21 days. Any file that exists on the Marketing Cloud FTP, that is older than 21 days, will be eligible for removal; and Marketing Cloud may remove it any time after 21 days. There is no assurance or guarantee that a file older than 21 days will be removed.
If you require a shorter retention period, for your files, you should use your provided FTP account to remove the files from your FTP location. Marketing Cloud will no longer apply new custom file retention periods to FTP directories.
Updated Information from salesforce
Answer: The files are retained for 21 days, You can talk to support to change this date.

Any file that is older than 21 days is eligible for removal, and we
can remove files any time after 21 days. However, there is no
assurance or guarantee of removal for files older than 21 days.

Source
Comment: Support will NOT adjust this time frame anymore


Why to use Chi2 instead of accuracy in a decision tree?

Question: Why many decision trees are using Chi2 or Information Gain Ratio to split the node when they can directly use accuracy, lift or AUC?
Answer: Many users of decision trees are comfortable and familiar with using and interpreting chi-squared tests and hence find it easy to use them in connection with decision trees as well. Of course, there are other ways to capture associations between the response and the input variables, but usually no single one measure outperforms all (or at least most) others on all (or at least most) datasets. So many researchers tend to prefer the measure that they are comfortable with or that performs particularly well on their dataset.
Another reason for using chi-squared tests is that they provide a means to separate the splitting variable selection from the split point selection. The work of Loh and co-workers (e.g., on QUEST and GUIDE) has shown that this can avoid so-called variable selection bias. This bias means that many exhaustive search strategies prefer splitting variables with many possible splits. Hence, trees based on statistical inference is used in many statistical decision tree algorithms (e.g., CTree).
Comment: Doesn't Chi2 also suffer from bias toward multinominal attributes like information gain?

And isn't it possible to deal with this bias by randomly splitting the data into training/testing set during the branch split and pick the branch split based on the best score on the testing set (something like C4.5 does during the prunning)?

And isn't the advantage of Chi2, IG and IGR in comparison to AC, AUC,... just in the fact that the values are NOT normalized by the sample size?
Comment: No, the bias does not come from the sample size (which might more often lead to overfitting than bias) but from only considering the best possible split for each variable. If this doesn't consider from how many possible splits the best one was chosen then there is a higher probability of selecting a variable with many possibly splits by chance. One can either address this by only using a fixed number of possible splits for variable selection only (as in QUEST or GUIDE) or by computing the correct maximally selected p-value (as in MOB or also possible in CTree).


Shortcut to view wireless networks in Windows 7

Question: Does anyone know how to create a shortcut which opens the wireless networks dialog box in Windows 7?  I'm looking for a shortcut that takes me directly to the window which shows you the available wireless networks around you.
Answer: create a new text file and put this on it
rundll32.exe van.dll,RunVAN

save it as "wifi.bat" and create a shortcut of it wherever you want,
right-click the shortcut, select propriety and edit its shortcut key to CTRL + ALT + W
now  Ctrl+ALT+W will popup that available Wireless network window.
Or use any other trick to map a keyboard shortcut to it ...
Have fun
Comment: If Explorer.exe isn't loaded, you might need to use `rundll32.exe van.dll,RunVANW` top get it top open up.
Comment: Tested and works on Win7, Thanks Revolter
Answer: Win + B is the built in key combination to get to the notification area. Then right arrow twice (or however many times you need) and Enter to show the available networks.
You could do this manually, or use Autohotkey to make your own single hotkey.
Answer: Create a shortcut on your desktop via right mouse, New, Shortcut, Location:
C:\Windows\explorer.exe shell:::{20D04FE0-3AEA-1069-A2D8-08002B30309D}\::{21EC2020-3AEA-1069-A2DD-08002B30309D}\::{38A98528-6CBF-4CA9-8DC0-B1E1D10F7B1B}

Press Next and name it "View Wireless Networks".
Then right click your shortcut and select properties, change Icon and select as file for "Look for Icons in this file" the following file:
%windir%\System32\wlanpref.dll

Select the icon you normally see in the lower right corner on the taskbar and press OK.
Answer: The whole wifi.bat did not work for me... here is what worked

Click on Start
Click on Control Panel
Click on Network and Internet
Click on Network and Sharing Center
Choose Change adapter settings on the Task pane
Right-click on Wireless Network Connection - and drag it to Desktop and select create shortcut.
Right Click that shortcut and select properties and make a shortcut key (mine is "CTRL+ALT+W"

If Wifi is disabled this will turn it on instantly
If WiFi is enabled it will bring up connection window where you can press "Deactivate"


Disconnectors Symbol in Single Line Diagrams (SLD)

Question: where should the moving part of a disconnector be located when breaking gets applied, on the energized side or on the disconnected side?
Is there any standard??
Suppose a non ring, simple grid and mention the authenticated sources for as much as possible please.
Comment: @IgnacioVazquez-Abrams: It doesn't sound like university homework to me. It is a legitimate question that would come up when doing real-world engineering design.
Comment: Quickly looking at some drawings I have lying around, it is always drawn with the moving part on the disconnected side. I will do a bit more research when I get home.
Comment: I appreciate Li-aung, and looking forward to more of your comments.
Answer: The moving part is almost always on the load (de-energised) side, for the following reasons:

If it is three-position disconnector (closed-open-earthed), the load must be connected to the moving part so that it can be earthed.
If you have a fuse-switch-disconnector, the fuses are typically on the moving part. You want the moving part to be de-energised so you can safely access/inspect the fuses.

There may be more reasons but those are the main ones that come to mind right now.
Be aware that the orientation shown on the drawing often does not reflect reality, and at higher voltages many disconnectors are either rotary (double-break) or centre-break types, even though they might be shown on the SLD using the standard disconnector symbol.
Comment: I'd add that there are standard symbols, but whether people use them or not is another matter.  In Australia/NZ for example we have AS/NZS 1102 - Graphical symbols for electrotechnical documentation.
Comment: There is no standard, you need to make a decision based on what is best for the situation. In terms of drawings, switches/breakers/disconnectors are usually drawn with the moving part at the bottom.
Comment: ^ What he said.
Comment: Thank you, is there any standard ?!


Destructive bureaucracy and how to oppose it

Question: In my country researchers are overburdened with paperwork and are struggling with increasingly overwhelming bureaucracy while being underpaid. This all leaves them not much time for actual research and demotivates them. What is the best way to make impact against such trend? When I discussed such issues with my colleagues they all seemed depressed and pessimistic. They can't imagine any kind of protest and noone believes in succesfull lobbying since science isn't "politically attractive". All other social groups (from teachers to medical doctors and from miners to farmers) are able to protest. Why can't we?
Comment: "Bureaucracy is expanding to meet the needs of an expanding bureaucracy." — Ian Parberry
Comment: _Why can't we?_ Did you go to those people who said "No"? If yes, what's the reason they said "no"? Legal issue? Or something else?
Comment: This situation sounds familiar. It is one of the reasons why I left my country. Answering why science can't effectively lobby, scientists don't produce an immediate return, so if you strike, no one is going to notice for a long time.
Comment: @scaaahu I talked with them face to face and the reason they said "no" is not legal. Constitutionally we have the right to protest. We even don't have an oppressive government. Noone wants to protest because "noone would even notice. What do you want to do, to make people notice scientific strike? That's ridiculous!". Anyway everyone just seems to be pessimistic and powerless.
Answer: This is a very old question. People in my country are also insane and love their bureaucracy. What I learned is that they are also deadly afraid their paperwork won't be done right. So, I started to get the people at the offices to do my paperwork for me. It is their job anyway.
When I got first into my job, my first idea was to gather enough support from my colleagues to mount a strong protest. I heard, but I can't find a link, that Polish researchers got fired the staff of their state grant agency after complaining how those guys hinder them. It is not possible in my country, and it may not be possible in yours. So, in my experience, the best way is to totally neglect paperwork except for what is essential: travel-related and buying equipment for research. Then, your bureaucrats will come begging for signatures and you train them like that. If you get chewed on by your boss, you can just reply that you "forgot", you are "very sorry", etc.
In any case, giving up the notion that you'll ever do competitive research in a system like that might help, but I didn't succeed at that myself.
Answer: Movements for social change are often driven by young people.  See if you can make some alliances and connections with student groups about some of their concerns.
I'd be interested to know more about the tedious paperwork that is required.  Maybe there are some creative ways to cut down on the time needed for the paperwork.


"Android" missing in my "Eclipse Juno 4.1" preferences

Question: actually i downloaded "Eclipse Juno 4.1" but can't give Android SDK path because it doesn't have "Android" option in "Preferences" menu.
Answer: Did you install android plugin for eclipse?
Start Eclipse, then select Help > Install New Software....
Click Add, in the top-right corner.
In the Add Repository dialog that appears, enter "ADT Plugin" for the Name and the following URL for the Location:
https://dl-ssl.google.com/android/eclipse/
Answer: I know its a stupid question, but did you install Android Development Tools into your Eclipse Juno installation from http://developer.android.com/sdk/eclipse-adt.html?
PS.: Eclipse Juno should be 4.2; Eclipse Indigo corresponds to 4.1 as far as I know.
Comment: According to the Juno download page (http://eclipse.org/downloads/index-developer.php) Juno should be version 4.2. The only possible (but improbable) solution is that some version numbers weren't increased, so you might have seen this inconsistency in version numbering.
Comment: but i downloaded this one exactly about which you are talking and from the very same page as well.
Comment: OK, you were right. I downloaded the same version now. It really is 4.2, just the branding plug-ins have not been updated to state that. So the About page and the splash screen still says 4.1. Sorry about the confusion, I did not know this.
Answer: You should update you'r eclipse to Eclipse Juno 4.2, follow this step
Click "Help" => "Check for Updates"
The Eclipse automaticly update version to Juno 4.2
then finish, Now you must follow this step for update eclipse plugin
https://developers.google.com/eclipse/docs/install-eclipse-4.2


Source for saying Parshas Hamon?

Question: There is a segulo for parnoso which is to read Parshas Hamon every day after davening. I have seen people "quote the Yerushalmi" for this but I have been unable to locate its source. Can anyone shed some light on the origins of this segulo?
Comment: closely related: https://judaism.stackexchange.com/q/5214
Answer: The oldest source I found was the Sefer haManhig (Shabbat 44) by R' Avraham ben Nathan:

בסוף יומא ירושלמי – כל האומר פרשת המן בכל יום, מובטח לו, שאין מזונותיו נחסרין.
At the end of Yerushalmi Yoma [it is said] – Whoever says the chapter of the manna each day, it is assured for him that he wouldn't lack his sustenance.

R' Bachya mentions a similar teaching in Beshalach 16 (end of top left column).
The custom is also brought by the Tashbetz (256), disciple of the Maharam of Rothenburg:

ירושלמי – כל האומר פרשת המן בכל יום, מובטח הוא שלא יתמעטו מזונותיו, ואני ערב.
[It is written in the] Yerushalmi – Whoever says the chapter of the manna each day, he is assured that his sustenance will not decrease, and I guarantee.

If you check the comments in the side notes, you can see that this custom is brought by many other rabbis, but they couldn't find its source in the Yerushalmi either. The Arukh Hashulchan 1:24 copies the words of the Perishah (fourth row from top), but he also mentions that he was unable to find it. Many authors say therefore that we don't have that version of the Yerushalmi now in our hands that our rabbis had in the past.*
* I've found this article a particularly useful source.
Answer: Dov Baer Ratner discusses this issue in Ahavat Tzion vYrushalayim on Yoma, pg. 103-4. It seems that the Sefer haManhig (an obscure rishon) had a version of y. Yoma that continued a bit further, including this and other statements. Most are found elsewhere in the Yerushalmi, but not this one. None of the Geonim seem to have had this text, nor any of the mainstream rishonim. It has been embraced now by a millenium of mystics but personally I do not think it likely that this was ever a real Yerushalmi. It fits much better into 13th century (when it was first quoted) Kabbalistic thinking that it does into the Yerushalmi, and some of those Kabbalists were notorious forgers.
Comment: Consider reading the story of the Leiden codex and how the text of the Yerushalmi got preserved. https://en.wikipedia.org/wiki/Jehiel_ben_Jekuthiel_Anav
Comment: I am familiar with the Leiden codex and the Yerushalmi generally. The best introductory essay BTW is Zussman's, printed in the Akademia edition. To be more specific: The Talmud is extremely wary of claims that individual acts of piety could earn immediate rewards, let alone guarantee them. The Talmud uses phrasing like this but with a reward to be experienced in heaven or a reward for descendants, etc. And even in these cases, cf. b. Yoma 47a on Qimchis e.g. In several places the Sages refuse to interpret Ps. 37:25 literally. In contrast the medieval Kabbalists saw pesuqim as magic spells.

Source for saying Parshas Hamon?


Querying an ethereum contract without ABI, with only input bytes

Question: I know some transaction has some input bytes to the contract as specified by Etherscan or a mining pool (for instance, this transaction has input data that looks like 0x000000062de258...9b1d). I know how to deserialize that into json, and I want to send those bytes to another contract. How do I send the identical transaction data, using say ethers with hardhat or geth, without knowing the ABI of any of the contracts involved?
Answer: If you use Ethers than you can create a signer (e.g. Wallet) and call sendTransaction with the data and to that you want.
With hardhat-ethers you can get all available signers with await hre.ethers.getSigners()
You can also do this directly via MetaMask:

An example where this is done can be found here (at 1:35): https://www.loom.com/share/ca34aabcd62747fb9fb89bd463b4c741


i have a usb floppy drive. how do i format a floppy disk with the ext2 file-system?

Question: I have ubuntu-14.04.1-server-amd64 operating system installed on my desktop computer. it is a clean installation. i have a USB 3.5 floppy drive. I need to format a floppy disk with the ext2 file-system. what do I need to do if i have the ubuntu-14.04.1-server-amd64 operating system up and running now? I need to be able to use the formatted floppy disk in a subsequent re-installation of ubuntu-14.04.1-server-amd64 operating system. The installation part of the operating system has to be able to identify the formatted floppy as "/dev/fd0" so that it is able to load GRUB on to the floppy.
Answer: For a pretty graphical way to do it, install/use gparted or even gnome-disk-utility ("Disks"). I strongly prefer gparted, gives more options and tells you more details on what it does, Disks may work, but seems more like a black-box "click and hope" solution.
Or, you can use the terminal tools yourself, using mkfs.ext2 (alias to mke2fs). If your floppy drive is /dev/fd0 then this command should make an ext2 filesystem on the floppy drive, using ext2 and automagically figuring out the other parameters (see man mke2fs for all the options). This would use the whole floppy disk with no partitioning, probably the same as gparted would do, I'm not sure.
mkfs.ext2 -t ext2 /dev/fd0

Making the disk bootable / setting bootable flag isn't an ext option, I always use gparted to do that, or even gnome disks, but you can use the terminal program fdisk like fdisk /dev/fd0 and then the a command to toggle the bootable flag (may need to add 1 for the 1st partition), then w for write.
Or if your floppy drive isn't /dev/fd0 then you could try lsblk or maybe blkid and see if it's listed, or after you plug it in check the logfiles and it should be listed in there somewhere (use dmesg or browse through /var/log/syslog and it should have some info. I think /dev/fd0 is the standard name for floppy drives, but with a usb floppy drive it could be different, I suppose you could try linking /dev/fd0 to whatever name the usb floppy drive is called if it's different, but I've never tried to needed to try that.
And installing grub to a floppy disk should work, though a cd/dvd/usb would be big enough for a whole ubuntu live iso, and might be easier. Unless your computer won't boot from usb or doesn't have a cd/dvd drive...
Answer: Download "Disks" from Software Manager. Insert your floppy. Open "Disks" (from Settings Manager). Select your floppy. Click gear button. Select "Format" and choose ext2 from system pop up list. Check "bootable" checkbox. Format it.
If you want to use the floppy for stand alone installation live disk - take into consideration that the floppy size (1.44Mb) is not enough even for minimal Ubuntu iso image (~30-50 Mb). I would consider to use USB stick instead of FD


What is known about global well ordering of classes in Gödel-Bernays?

Question: I would like to have something like a linear order on classes, such that every instantiated predicate of classes has a minimal instance in that order.  For my purposes, it is fine to assume V=L for sets.
Comment: @AsafKaragila  I want well ordering not *in* classes, but *of* classes.
Comment: I'm not quite clear as to what you mean. If you assume $V=L$ then you have a definable well-ordering of the sets, therefore every non-empty class must have a least element.
Answer: In the context of models of second-order arithmetic, Mostowski showed that starting with the theory $Z_2$ (the second-order arithmetic analogue of Kelley-Morse) together with the scheme of dependent choices, one can use forcing to add a well-ordering relation on classes so that the full second-order comprehension scheme continues to hold in the language with the new relation. The argument appeared in his paper "Models of second order arithmetic with definable Skolem functions" [Fund. Math. 75 (1972), 223–234] and was later corrected in "Erratum to the paper `Models of second order arithmetic with definable Skolem functions'" [Fund. Math. 84 (1974), 173]. Initially, Mostowski used only the choice scheme to prove the result.
Mostowski's argument generalizes to the theory Kelley-Morse together with the scheme of dependent choices. The scheme of dependent choices states that if a second-order definable relation has no terminal nodes, then it has an $\omega$-chain. The forcing is supposed to be akin to the forcing argument that a global well-ordering class can be added to a model of ZFC, but in this case the condition are classes, and so we have a hyperclass forcing (in Sy Friedman's terminology). I only know about this construction from conversations with Ali Enayat, who will probably give many more details when he is around.
Comment: Terrific.  I will take some time to absorb this.  Since I really want this in a weak fragment of ZFC, the use of $Z_2$ is very encouraging.
Comment: @ColinMcLarty I think the key to making the argument work is having full second-order comprehension (which GB doesn't have) plus the dependent choice scheme for classes. This is, I think, what is needed for hyperclass forcing to preserve comprehension in the extended language. But I am hoping Ali will be here to say more.
Comment: A beautiful result.  I fear it sinks my strategy for the problem that led to this question, but maybe that failure points the way to what will work.


Running Android apps in Linux

Question: I have a Red Hat Linux (RHL) system on which I'd like to run Android apps. How would I do this? Is there an open-source port of the Android Runtime for linux? Kind of like a VM?
If not, what steps will I need to follow to port the runtime to RHL (with the Dalvik VM etc) so that I can run the android apps built by all android developers?
I am new to android so I am trying to understand if there is an application virtualization support for it from anyone. Thanks in advance!
Comment: You will be able to run them, it's working in progress. And this feature will bring Linux to desktops. Stay tuned!
Comment: @lzap That's exciting!! Could you give us a little more detail? For example what is the name of the project, and who are behind it? Thanks!
Comment: Well it's all bellow, read it :-)
Answer: You need to use dex2jar to convert an APK file to a JAR and then you need IcedRobot to run the Android stack above OpenJDK. Maybe I will try to emulate AndroidGL with JOGL 2.0 (it supports both OpenGL and OpenGL-ES). Keep in mind that it is not trivial.
The emulator of Android SDK is quite slow but you just have to enter adb install my_file.apk to install your application.
You can run android-x86 in VirtualBox or Live Android from a Live CD as Dimitri suggested but I'm not sure it is what you want.
P.S: The most promising solution seemed to be AndroVM.
P.S 2: ARChon Runtime works very well on 64-bits systems. This tutorial is very helpful to make it work.
P.S 3: App Runtime for Chrome Welder is even more promising, it's currently in beta. The final version will support all Android APIs in Google Chrome under GNU Linux (including Chrome OS), Mac OS X and Windows.
Comment: Hi @gouessej . I have a project about running  Android's OpenGL API on platforms supporting  awt Canvas. [GitHub](https://github.com/AlessandroBorges/madri-gles). Still under development due other project to bind Vulkan on Java...
Comment: Why not using JOGL to access OpenGL-ES instead of LibGDX + your own JNI code?
Comment: I'm not using LibGDX. At the time I start it, I needed a very thin layer for GLES,  in order to make portable applications for Android and desktop platforms. So I choose to implement **android.opengl** API in desktop environment.  It also easy prototyping Android GLES applications.
Answer: I know there is a project for porting Android on x86 platform. You can find iso to download and you can install on LiveCD : http://code.google.com/p/live-android/. You can find more information here
Comment: I think It's not what people want. Adnroid is a good OS for smartphone but not for computer. What user716222 and what I'm lookinf for is a Android VM for Linux (or Windows) to be able to run Android Apps.
Comment: Could be wrong but this project looks dead.  I don't see any versions released after 2009.
Answer: You can't just run Android apps - you will need the entire underlying Android operating system. That goes beyond a simple JVM. EDIT: There is actually a project in the works that aims to do that, see Dimitri's link.
But you're in luck - the Android SDK comes with an emulator that should fulfill your needs (although it's a bit on the slow side - if you're developing Android apps, you definitely want to use a physical device instead). The SDK is available here.
Comment: "You can't just run Windows apps - you will need the entire underlying Windows operating system" — the truth is in wine. Do I miss something in case with android? Please, elaborate then.
Answer: Run Bluestacks on Windows on VMWare on Linux. Easy.

Running Android apps in Linux


How to find pantone shades of a particular color?

Question: A client came to me with their logo for a campaign and wanted me to do the collaterals. I did a few thing for her. Now she wants me to give her the names of pantone colors matching the exact two colors in her logo. How do I find the pantone shades for them?
Please help!
Thanks
Comment: The best way to choose would be with a Pantone Color Book. Sounds like to me they don't have Pantone colors chosen yet, so you have the luxury to choose them for her, whether with the book or digital.
Answer: Official Pantone Color Finder:
www.pantone.com/color-finder
In the long term you might want to get yourself a paper guide. But they are expensive ...
www.pantone.com/fashion-home-interiors/paper-products
Maybe you could go to a local print shop or design studio in your area and ask them to have a look at their paper guide.
Update:
As @Rafael pointed out in the comments, the web picker from Pantone doesn't accept RGB or HEX. So here is:
How to pick a Pantone color in Photoshop:

Select your color with the color picker and click 'Color Libraries':

From the 'Book' dropdown menu select your preferred Pantone scale.

Pick the Pantone color you like best. (Photoshop will suggest one.)
Comment: The problem with that page is that you can not input a hex, rgb cmyk values. Only another Pantone color. Another thing is that if you input one color that has no exact match, it spits back a ton of diferent options.
Comment: @Rafael True. I didn't notice that. Thanks for pointing it out. I have added a different method in my answer ...


Determining the mass and center of mass over a circular region

Question: The problem reads:
Provided the region $ C = \{ \left( x, y \right) | x^2 + y^2 \le 1 \}$, find the mass and center of mass of $C$ if the density $ \rho \left( x, y \right) $ of each point in $C$ is proportional to the distance of the point from the $y$-axis.
The region described by $C$ is a circle with radius 1 centered at the origin and containing all points within it.
In order to find the mass of $C$ with respect to the given $ \rho \left( x, y \right) $, I used two sets of double integrals in an attempt to determine the mass: one in rectangular coordinates and one in polar coordinates.
For rectangular coordinates, $ \rho \left( x, y \right) = kx $, where $ k \gt 0 $.
For polar coordinates, $ \rho \left( r, \theta \right) = kr \cos{\theta} $ , where $ k \gt 0 $. $ (x \to r \cos{\theta}) $
\begin{align}
\text{mass of C} & = \iint_C \, kx \, dA \\
 & = 2 \left( \int_{-1}^1 \int_0^\sqrt{1-x^2} kx \, dy \, dx \right) \\
 & = 2 \left( \int_{0}^{2\pi} \int_0^1 kr^2 \cos{\theta} \, dr \, d\theta \right)
\end{align}
Solving both double integrals yields a mass of $0$.
However, in order to yield the center of mass of $C$, I would have to determine the first moment of the mass about the $y$-axis $ M_y = \iint_C \, x \rho \left( x, y \right) \, dA $ and the first moment of the mass about the $x$-axis $ M_x = \iint_C \, y \rho \left( x, y \right) \, dA $.
The coordinates for the center of mass are
$$ \left( \frac{M_y}{mass}, \frac{M_x}{mass} \right) $$
Attempting to solve for the $x$- and $y$-coordinates cannot be done since the mass is $0$.
Is there something wrong with how I set up the problem? Is it preferable to use one coordinate system over another?
Comment: Your density function gives negative values for points left of the $y$-axis.
Answer: Your error lies on the inside of the double integral. Because distance should always be a non-negative number, the density function wouldn't be $kx$, but rather $k |x|$. You would then need to set up two separate double integrals and then your mass wouldn't be zero


Audio signal processing book suggestions

Question: I want to start learning about audio signal processing but I cannot find a good starting point. Please suggest books or lecture series.
Comment: Make sure you get the basics down: Sampling and reconstruction theorem, Fourier Transforms, Convolution.  After that you'll get to think about non-linear and time-variant techniques, but get the LTI down first.
Comment: I think that a general book on signal processing (plus linear algebra and statistics) is a good starting point. If you want to specialize in audio, it depends on your interest. Speech processing? Music? Stage, movie, games, VR...? Machine learning and acoustics would be useful.
Answer: If you can get it:
Zölzer, Udo (1997). Digital Audio Signal Processing. John Wiley and Sons. ISBN 0-471-97226-6
or
Orfanidis
might have to buy them used.
is your interest music processing and synthesis?
there are some nice online books.  Look for anything Julius Smith.  But there are others, but i can't remember any names to search for.
Remembered one:
Davide Rocchesso
here's another link
another old one:
Ken Steiglitz
Comment: i don't think that they are the same book, @moinudin.
Comment: +1 for Orfanidis. Zölzer is also okay, even though the formulas in that book have to be taken with a grain of salt.
Comment: i knew Orfanidis before he did that book.  he did a sorta generalization to my *"Equivalence"* paper in the '90s.  Knud Christianson did a better one, but Orfanidis was first to do something to nail down the 5th degree of freedom.
Comment: With Orfandis, is there a significant difference between the "Introduction to" book you linked to and another I found: https://www.amazon.co.uk/dp/0070477949/ I can't tell if they're the same with slightly different titles/covers.
Comment: Phew. Because I was finding that one really difficult. Fortunately I found the introductory one, and I can see its quite different. Thanks!
Answer: My personal favorite, though I don't usually do much audio signal processing, are Julius O. Smith III's Spectral Audio Signal Processing and Physical Audio Signal Processing. They're available online here and here.
A while ago, he made the Physical book available in paperback on Amazon.
Answer: Many years ago, when I was studying audio DSP in my university, I had to read the following:
Y. You, "Audio Coding: Theory and Applications," Springer, 2010 here
A. Spanias, T. Painter, V. Atti, "Audio Signal Processing and Coding," Wiley, 2007 here.
I was very dissapointed by both. Spanias & Painter provide a nice and thorough overview of MP3 coding (but it contains many typos) though. After a couple of years, I read the books by J. O. Smith III, also mentioned by @Peter K. These are indeed excellent textbooks.


Count Number Of Words In a Textarea

Question: I have a text area that gets input from a PHP script, and I would like to count the number of words or line breaks in the textarea and echo it below the text area.
This is what the code looks like for the textarea.
<textarea name="domains" cols="120" rows="5" style="max-width:100%;">
    <?php $output_array = explode(" ",$output);
    $count = count($output_array);
    for ($i=0;$i<$count;$i++){
    echo $output_array[$i]."\n";
    }
    ?>
</textarea>

        <?php
        preg_match_all("/(\n)/", $_POST['domains'], $matches);
         $total_lines = count($matches[0]) + 1;
         echo $total_lines;
        ?>

I tried using preg_match_all but the output I get is only "1", regardless of how many line breaks are inside the text area.
Comment: _"I can't seem to make it work"_ is a vague description - strive to describe exactly what happens and also include some sample data and your desired result.
Comment: `/\w+/` You can use \w for words and not \n
Answer: $str = 'as aa frd sad as
kjhsdf sdkjh
sd sdkjhsdf
sjkldhfh sdfjh sd';

preg_match_all("/\w+/", $str, $matches);
echo 'Words = ' . count($matches[0]);
echo PHP_EOL;
preg_match_all("/\n/", $str, $matches);
echo 'newlines = ' . count($matches[0]);
echo PHP_EOL;
echo 'So number of line is = ' . count($matches[0])+1;

RESULT
Words = 12
newlines = 3
So number of line is = 4

Answer: You can do the following:
$arr = array_filter(explode(" ", $input) function($item) {
    return !!$item;
});

$count = count($arr) + count(explode("\n", implode(",", $arr)));

This splits the string by space, filters out empty items to avoid issues due to multiple spaces found between words, then glues the array back into a string, splits it by newline and adds the two counts together.

Count Number Of Words In a Textarea


How do you update a live, busy web site in the politest way possible?

Question: When you roll out changes to a live web site, how do you go about checking that the live system is working correctly?  Which tools do you use?  Who does it?  Do you block access to the site for the testing period?  What amount of downtime is acceptable?
Comment: The discussion in this question may also be of use to you --  http://stackoverflow.com/questions/148084/how-to-deploy-an-asp-net-application-with-zero-downtime
Answer: I tend to do all of my testing in another environment (not the live one!).  This allows me to push the updates to the live site knowing that the code should be working ok, and I just do sanity testing on the live data - make sure I didn't forget a file somewhere, or had something weird go wrong.
So proper testing in a testing or staging environment, then just trivial sanity checking.  No need for downtime.
Answer: Lots of good advice already.
As people have mentioned, if you don't have single point involved, it's simple to just phase in changes by upgrading an app server at a time. But that's rarely the case, so let's ignore that and focus on the difficult bits.
Usually there is a db in there which is common to everything else. So that means downtime for the whole system. How do you minimize that?
Automation. Script the entire deployment procedure. This (especially) includes any database schema changes. This (especially) includes any data migration you need between versions of the schema.
Quality control. Make sure there are tests. Automated acceptance tests (what the user sees and expects from a business logic / experience perspective). Consider having test accounts in the production system which you can script to test readonly activities. If you don't interact with other external systems, consider doing write activities too. You may need to filter out test account activity in certain parts of the system, especially if they deal with money and accounting. Bean counters get upset, for good reasons, when the beans don't match up.
Rehearse. Deploy in a staging environment which is as identical as possible to production. Do this with production data volumes, and production data. You need to feel how long an alter table takes. And you need to check that an alter table works both structurally, and with all foreign keys in the actual data.
If you have massive data volumes, schema changes will take time. Maybe more time than you can afford to be down. One solution is to use phased data migrations, so that the schema change is populated with "recent" or "current" (let's say one or three months old) data during the downtime, and the data for the remaining five years can trickle in after you are online again. To the end user things look ok, but some features can't be accessed for another couple of hours/days/whatever.
Answer: At work,  we spend a period of time with the code frozen in the test environment.  Then after a few weeks of notice, we take the site down at midnight Friday night, work through the night deploying and validating, and put it up Saturday late morning.  Traffic statistics showed us this was the best time frame to do it.
Answer: If you have a set of load-balanced servers, you will be able to take one by one offline separately and update it. No downtime for the users!
Answer: At the last place where I worked, QA would perform testing in the QA Environment.  Any major problems would be fixed, tested, and verified before rolling out.
After the build has been certified by QA, the production support team pushed the code to the Staging environment where the client looks at the site and verifies that everything is as desired.
The actual production rollout occurs during off hours (after 9 p.m. if it is an emergency night push, or from 5 a.m. - 8 a.m. if it is a normally scheduled rollout).
The site is hosted on multiple servers, which are load balanced using an F5 Load Balancer:

A couple of the servers are removed from production,
code is installed, and
a cursory check is performed on the servers before putting the servers back in the pool.

This is repeated until all of the servers are upgraded to the latest code and allows the site to remain up the whole time.
This process is ideal, but there are cases when the database needs to be upgraded as well.
If this is the case, then there are two options, depending on if the new database will break the site or not.
If the new database is incompatible with the existing front end, you have no real choice but to have a window of time where the site is down.
But if the new database is compatible with the existing front end, you can still push the code out without any actual downtime, but this requires there to be two production database servers.

All traffic is routed to the second DB and the first DB server is pulled.
The first DB is upgraded and after verification is complete, put back in production.
All traffic is routed to the first DB and second DB is pulled.
The second DB is upgraded and after verification is complete, put back in production.
The next step is to perform the partial upgrades as described above.

So to summarize:

When you roll out changes to a live web site, how do you go about checking that the live system is working correctly?  In the best case, this is done incrementally.
Which tools do you use? Manual checks to verify code is installed correctly along with some basic automated tests, using any automation tool.  We used Selenium IDE.
Who does it?  DBA performs DB upgrades, Tech Support/System Admins push/pull the servers and installs the code, and QA or Production support performs the Manual Tests and/or runs the Automated tests.
Do you block access to the site for the testing period? If possible, this should be avoided at all costs, especially, as Gilles mentioned earlier, if it is a paid site.
What amount of downtime is acceptable? Downtime should be restricted to times when users would be least likely to use the site, and should be done in less than 3 hours time.
Note: 3 hours is very generous.  After practice and rehearsing, like jplindstrom mentioned, the team will have the whole process down and can get in and out in sometimes less than an hour.

Hope this helps!
Comment: what if we have only 1 server??
Answer: Have a cute, disarming image and/or backup page.  Some sites implement simple javascript games to keep you busy while waiting for the update.
Eg, fail whale.
-Adam
Answer: Some of that depends on if you're updating a database as well. In the past, if the DB was being updated we downed the site for a planned (and published) maintenance period - usually something really off hours where impact was minimal. If the update doesn't involve the DB then, in a load balanced environment, we'd take 1 box out of the mix, deploy & test. If that was successful, it went into the mix and the other box (assuming 2 boxes) was brought out and updated/tested.
Note: We're NOT testing the code, just that the deployment went smoothly so down time any way was minimal. As has been mentioned, the code should have already passed testing in another environment.
Answer: IMHO long downtimes (hours) are acceptable for a free site. If you educate your users enough they'll understand that it's a necessity. Maybe give them something to play with until the website goes back up (eg. flash game, webcam live feed showing the dev team at work, etc). For a website that people pay to access, a lot of people are going to waste your time with complaints if you feed them regular downtime. I'd avoid downtime like the plague and roll out updates really slowly and carefully if I were running a service that charges users.
In my current setup I have a secondary website connected to the same database and cache as the live copy to test my changes.
I also have several "page watcher" scripts running on cron jobs that use regular expressions to check that the website is rendering key pages properly.
Answer: The answer is that "it depends". First of all, on the kind of environment you are releasing into. Is it "hello, world" type of website on a shared host somewhere, or a google.com with half a mil servers? Is there typically one user per day, or more like couple million? Are you publishing HTML/CSS/JPG, or is there a big hairy backend with SQL servers, middle tier servers, distributed caches, etc?
In general -- if you can afford to have separate environments for development, QA, staging, and production -- do have those. If you have the resources -- create the ecosystem so that you can build the complete installable package with 1 (one) click. And make sure that the same binary install can be successfully installed in DEV/QA/STAGE/PROD with another single click... There's tons of stuff written on this subject, and you need to be more specific with your question to get a reasonable answer
Answer: Run your main server on a port other than 80.  Stick a lightweight server (e.g. nginx) in front of it on port 80.  When you update your site, start another instance on a new port.  Test.  When you are satisfied that it has been deployed correctly, edit your proxy config file, and restart it.  In nginx's case, this results in zero downtime or failed requests, and can also provide performance improvements over the more typical Apache-only hosting option.
Of course, this is no substitute for a proper staging server, it is merely a 'polite' way of performing the handover with limited resources.
Answer: To test everything as well as possible on a
separate dev site before going live, I use Selenium
 (a web page tester) to run through all the navigable
parts of the site, fill dummy values into forms, check
that those values appear in the right places as a result, etc.
It's powerful enough to check a lot of javascript or
dynamic stuff too.
Then a quick run-through with Selenium again after
upgrading the live site verifies that the update
worked and that there are no missing links or database errors.
It's saved me a few times by catching subtle errors that
I would have missed just manually flicking through.
Also, if you put the live site behind some sort of "reverse proxy"
or load balancer (if it's big), that makes it easy to switch
back to the previous version if there are problems.
Answer: The only way to make it transparent to your users is to put it behind a load balanced proxy. You take one server down while you update another server. Then when you done updating you put the one you updated online and take the other one down. That's how we do it.
If you have any sort of 'beta" build, don't roll it out on the live server. If you have a 'live, busy site'  chances are people are going to pound on it and break something.
This is a typical high availbility setup, to maintain high availability you'll need 3 servers minimum. 2 live ones and 1 testing server. Plus any oter extra servers if you want to have a dedicated DB or something.
Comment: The difficult bit here is that when you have a load balanced proxy you likely have a database.  Changing data/schema/DB code is the tougher bit that load balancing won't help.
Answer: Create a host class and deploy your live site on that host class. By host class I mean a set of hosts where load balancing is setup and its easy to add and remove hosts from the class.
When you are done with the beta testing and ready for production, no need to take your site down, just remove some host from production host class, add them in new host class and deploy your latest code there and test properly. Once you are sure that everything is working fine move all your host gradually to the new one and point new host class as production host class. Or you can use the same you were using initially, whole idea behind this activity is to make sure that your are testing your deployment on the production boxes, where your site will be running after deployment, because deploy issues are scary and hard to debug.


Will it be possible to use GTK3.2's HTML5 extension in 11.10?

Question: Does anybody know wether or not it willbe possible to use the GTK3.2's new HTML5-extension in Ubuntu 11.10? They announced that GNOME3.2 will be included, but will they build the GTK packages with the new HTML5-extension enabled?
Comment: That is a very interesting question. You do mean if you can run any standard GTK applications as a browserapp? Or if you can develop 3.2 apps that supports it?
Comment: Well, at first I would like to know, if I can run any GTK application as a browser application in the next Ubuntu release. But then I it would be interesting as well to know, how to develop those applications.
Answer: Not in Oneiric, it seems, but it should be possible in 12.04. Since this was only released a couple of days ago, it was probably too late to get it in 11.10. The GTK applications will just work. You'll run them like this: GDK_BACKEND=broadway someapp.


Transforming NED Acceleration Profile to Body Frame through Quarternions

Question: I have an acceleration profile which is in the North-East-Down coordinate system. The moving object in question is 6 DOF, however, and frequently approaches 90 degrees in roll, pitch, and yaw, making Euler angles a poor means for the transformation. I'm very inexperienced with quaternions and having a hard time making, if not figuring out if it's even possible to do this. I'd like to have a quaternion rotation matrix that changes my velocity profile from inertial to body frame horizontal and vertical accelerations if possible. I'll take anything that might help.
Comment: I know a lot about quaternions and rotations with quaternions but I have no idea what you just said. (Don't worry, that's typical of quaternion questions.)  If you have a rotation in mind and you know its axis and the angle it rotates around the axis, then finding the quaternion is easy. Do you know the axis and angle of rotation (at each point of time?)
Answer: I will assume that your local coordinate system corresponds to your global coordinate system when yaw, pitch and roll are zero.  By that I mean that x = forward, y = right, z = down (SAE standard).  I will also assume that yaw, pitch and roll are done with respect to local axes in that order in the right hand sense.  By this I mean that first you yaw about Z (CW), then pitch about Y (Up) and then roll about X (right).  You can then define a quaternion for each of these.  Let $\psi = $ yaw angle, $\phi = $ =pitch angle, and $\theta =$ roll angle.  Then:
$$q_y = [\cos(\psi/2), (0,0,1)\sin(\psi/2)]$$
$$q_p = [\cos(\phi/2), (0,1,0)\sin(\phi/2)]$$
$$q_r = [\cos(\theta/2), (1,0,0)\sin(\theta/2)]$$
Then your composed rotation would be
$$q = q_y q_p q_r$$
in that order.  You can then rotate a vector $a = [a_x, a_y, a_z]$ from the global (NED) to local frame (SAE) by using the inverse transformation
$$\bar{a} = q^*aq$$
using normal multiplication rules for quaternions.  You can also work out a normal rotation matrix from $q$ if that is what you prefer.  The equation is found in many places on the web like here.
I gave you just the highlights assuming that you have some familiarity with the algebra of quaternions.
Comment: I am familiar with the basics of quaternion algebra, and so far this seems to be helping me get the numbers I expect! Thank you for the help and sorry for the long reply.


Open Source or free electric field mapping software

Question: Looking for recommendations for 2D (or 3D) electric field mapping software.  I want to be able to populate a series of electrodes in a plane and understand the equipotentials present when these electrodes are driven to different voltages.  Would like to model virtually first before realizing the design in a PCB/PWB to reduce cycle time.  Must be low cost or FOSS software.  Will be modelling fields in free-space and with patterns of electrodes, so no fancy lossy di-electrics or esoteric material need be supported.
Comment: Have you looked at FastCap and FastHenry?
Comment: @Samuel thanks for the lead.  Both of these programs calculate a fixed value (C or L) from the fields so on the surface no I can't use them.  But having you remind me of them I realize that if all else fails it will be possible to extract out the salient information by perturbing the design and rerunning it.  And since it's CLI it's scriptable!  Thanks
Comment: @Samuel on eth MIT page from teh code source there is fastmaxwell which does the job!  Thanks http://www.rle.mit.edu/cpg/research_codes.htm hopefully this can be applied to the static case.
Comment: Very nice. I wrote some Matlab scripts this summer that generate multi-layer planar spiral coil geometries and automatically generate input files for and invoke fasthenry/fastcap to extract inductance and capacitance. Also the script generates scripts for Eagle and Cadence PCB (Allegro) for automatic layout of said coils on PCBs. The simulated inductance matched with fabricated coils within 1.5% for 26 coils from 5µH-130µH. I was very impressed with the accuracy of those softwares, and their scriptibilities. Glad they'll work for you too.
Comment: Rather, I'm glad that something similar will work for you :)
Comment: Hopefully, this won't be hijacking, but I wanted to try this FastMaxwell and, for the life of me, I couldn't install fftw-2.1.5 as a dependancy, I could compile it, though, no problems (Linux). Is there any trick to this? Their help isn't very "helping".
Comment: I have given up on FAstCap2 and FAsterCap.  My design is too much for the tool and it crashes and also gives in consistent results.  I understand why, part of the issue is that to do his properly I have to model the surfaces better but I don't want to buy the mesh tool.  So for simple results it will work, with caveats.
Answer: QuickField Student edition - 2D finite element package - Windows
Trace Analyzer - Transmission line parameter calculator for PCB's - Win/Mac/Linux
SATE - Static Field Analysis Toolkit - 2D E-Field - Windows
Radia - 3D Static magnetic fields - Mathematica plugin
PDN Mesh - 2D field problems (Poisson and Helmholtz Equations). - Windows
OpenEMS - open electromagnetic field solver using the FDTD method. Matlab or Octave are used as an easy and flexible scripting interface. - Win/Linux
NEC2 - (Method of Moments) simulates the electromagnetic response of antennas and metal structures. - Win?linux
MMP - The Multiple Multipole Program (MMP) - Win/Unix
MEEP - Meep (or MEEP) is a free finite-difference time-domain (FDTD) simulation software package developed at MIT to model electromagnetic systems. - Win/Linux
LC - LC is simulation tool for the analysis of the electromagnetic properties of electrical interconnects. - Linux/Unix compile
EM Explorer - EM Explorer is a 3D electromagnetic (EM) solver for scattering problems of periodic structures illuminated by arbitrary incident fields including planewaves, Gaussian beams and focused Hi-NA beams - Windows
Atribution: Blurbs copied from respective web sites.
Comment: The list is nice. It would be interesting to sort them by Win Win/Linux Linux and add "no cost" or "open source" or even the license like GPL-2, MIT...


What is the browser engine on Android devices?

Question: Different vendors send non-Chrome browsers by default. Can I assume all of them to be Chromimum based?
Answer: No.
The default browser on stock Android is Google Chrome. This uses the Blink layout engine. For AOSP installations without the Google Apps, the default browser is the old "Browser" app that uses Webkit.
However, other browsers are available. Firefox uses Gecko, Opera uses Blink, Dolphin uses Webkit, and there are probably others. Additionally, I am informed in the comments that Samsung and HTC install different (non-Chrome) browsers on their phones. I do not know what they are, or what engine they use.
Summary: Android does not have a single browser or layout engine.
Comment: The default browser on Google Android is Chrome, the default browser on AOSP is the old 'Browser'. You are right, but there is a difference between 'Android' and 'Google Android', though it's a loose definition!
Comment: @rossC thanks, I hadn't considered AOSP. And I wasn't aware that Samsung and HTC replace Chrome... the last time I had an HTC phone, Chrome wasn't available for Android anyway!
Comment: Then there's Samsung's default browser for Android, HTC's default one and so on. The fragmentation of Android makes this an absolute pain. +1 for the answer though!
Answer: No, you can't. If you want a more specific answer than that, you need to give more details on what you're trying to achieve, but bear in mind that programming questions are off-topic on this site.


Hearing protection on the road in China

Question: I know it's not safe to have hearing completely blocked with earplugs while bicycling or driving. But there are a lot of vehicles on the road in China with extremely loud horns. I just had a truck blare it's horn next to me and it's still painful 20 minutes later. Is there a type of hearing protection that is safe to use when driving or riding?
Comment: @pnuts the question is not limited to cycling. I was in a car with the window rolled down when the truck blared its horn. It is true that the situation is worse when on a bicycle or motorbike. The blast causes one to feel momentarily disoriented which could lead to a loss of balance.
Comment: I agree, having walked almost under a tram in Amsterdam because there was work noise, cutting stone outside a building. It disoriented me so much I needed that pull on my arm not to get reduced to mush.
Comment: Sure we can just remove the 'China' part and have it on topic?
Comment: I haven't noticed such loud horns anywhere else in the world. Some smaller cars even have what would seem to be after-market modifications to make their horns louder. In addition, horns are used much more frequently in China, especially in smaller cities.
Answer: You could try ear protection which are designed to attenuate not eliminate noise. Currently dubs seem to be popular, designed for concerts and reduce sound by 12db only. But there are other options out there.

DUBS Acoustic Filters are advanced tech earplugs that reduce volume without sacrificing the clarity of sound

I've never tried them, but they get good reviews and people successfully use them for other uses.
A few other options with different sound attenuation but still claiming clear sound: "20db high fidelity" and  "three exchangeable filter sets for low, medium and high protection".
Until Doppler Labs launch their earbuds that:

let you customize how the world sounds around you

it's the best option i know. Be safe!
Answer: Almost all earplugs sold for work situations.
When working you are not supposed to block out all sounds and responsible employers will supply earplugs that take out the hard edge of sounds but not all of it.
The plugs you see for sale for travel are OK as well as long as you do not have the 'wax, you will not hear a sound when sleeping' kind.
And I have heard that many 'in ear' earphones reduce sounds without blocking all of it, just make sure you do not get the top of the range which comes close to blocking all sounds.

In-ears-earphones from Wikipedia, the free encyclopedia, these are the top end and might block more than you like.

Hearing protection on the road in China


What's the optimal distance from a pressure tank to the supply line connection?

Question: Is there an optimal distance from the pressure tank to install the Tee joining the line from the pump, line to the house and line to the pressure tank? We have a convertible jet pump with an injector bringing water from an 82 ft well. The line from the well comes up into the basement, the pump and pressure tank are within 8 feet of the well line. Currently the line comes out of the pump about 16" to a Tee with about a 24" line going to the pressure tank. All of this is at floor level with the house supply line running up the wall to the ceiling directly above.
Comment: Make the pipe long enough for easy access for repairs/maintenance.
Answer: The optimal distance is as close to the house feed line as possible. But "less than optimal" may not be enough difference to notice, particularly if the tank tee line is adequately large diameter. Are you experiencing a problem related to the pressure tank?
I'd personally be penciling in "replace with a submersible pump" for future water system considerations. Jet pumps are a technology whose time has come and gone, IMHO. They waste a lot of power, for one thing.
Comment: A "standard" tank tee is usually at least 1" pipe, so using 3/4" for that is not great, IMHO. The idea is to minimize flow-related pressure drop (aka dynamic head) into and out of the tank. Such "standard" tank tees are easily available, typically with a union to make tank replacement easier. *Unfortunate (unless there's some major issue getting power to the well) about the new jet pump.*
Comment: Thanks. Just replaced the pump & pressure tank so hope we've got a while before we need to do that again. The new pressure tank is providing adequate pressure. We were in a rush so just put the new pump & tank into the existing hose & clamp plumbing last weekend but want to replumb it from the pump to the house water line.
Comment: Another question. We plan to plumb with 3/4" PEX. Can we use PEX from the Tee to the pressure tank?
Answer: For what it is worth I have a 450ft deep well so if it really mattered then I should be having problems and I'm not.  Initially my pressure tank was at the entry point but when I finished my basement I relocated the tank to near the water heater on the other side of the basement which added 75 feet or so (being generous here) and it made ZERO difference.  I didn't even have to adjust my tank.  Let me add that the distance will have no bearing on the pump life.  Taking the overall quality of your pump out of the equation (you get what you pay for.). Pump life is generally dictated by two things being the quality of your source water and how often it runs.  If you have a tiny pressure tank your pump will run far more to maintain pressure.  If your water is hard or high in iron your pump will fail due to mineral or metal deposits clogging the intake.  Hope that helps.
Answer: The most important thing is to start at water pressure tank with 1 inch copper reduce to 3/4 then to 1/2 inch then to fixture of any thing and u will have optimal equal pressure at all units cause u did the proper volume displacement by graduating your plumbing from a greater pipe to a lesser pipe and u will never go wrong!Pax pipe or copper don't make a difference just go from greater pipe to lesser pipe!
Comment: Would you please [edit] your post to include some punctuation, that will make it much easier to read. Also, "you" is perfectly acceptable, and the savings of not transmitting the 2 extra characters are really pretty small. Additionally, is "Pax pipe" supposed to be "PEX pipe"? If not, you may want to specify what "Pax pipe" is as not everyone is familiar with that.


What is the flavor quality that makes cheese "sharp"? Are there other seasonings or foods with this "sharp flavor?

Question: I love the flavor of sharp cheese (especially cheddar) and was wondering what exactly it is that makes aged cheese taste sharper. I was also wondering if there are any ingredients that emulate this sharp flavor.
Comment: "Sharp" in the sense of cheese is an Americanism, and I think the language affects the perception.
Comment: Possibly but there is a definite flavor difference between cheeses described as mild vs sharp. And it differs from how other foods change their taste as they age. I feel like many cheeses get smoother as they age even if their flavor is stronger. But cheddar definitely gets tangier as it ages.
Comment: It might be [histamine](https://www.cheesescience.org/histamine.html)
Answer: The term/process you are looking for is acidity or acidification.  During the cheese making process lactose is broken down into lactic acid.  This lowers the pH and creates the tart, sour, or acidic taste you are referring to. Higher acid cheeses (lower pH) present as "sharper", an old cheddar, for example.  Ever have a salt and vinegar potato chip?  I get a similar flavor perception (minus the lactic, cheese flavors of course).  So, other acidic ingredients (vinegar, lemon) can easily get you in the same flavor perception ball park.
Answer: Perhaps you are referring to the umami flavor.
Per cooks illustrated:

There's more than one reason that classic combinations like a burger
and cheddar cheese or the Parmesan cheese and anchovies in a Caesar
salad taste so good: Not only do such ingredients simply go well
together but it turns out that they contain complementary umami
boosters that magnify flavor by as much as thirtyfold. More and more
food scientists are concluding that when ingredients rich in naturally
occurring glutamates are paired with ingredients that contain either
one of the nucleotides inosinate or guanylate, the perception of
umami, or savoriness, is dramatically

Rich In Glutamates
(MG/100 G)

Parmesan cheese  1,200-1,600
Fish Sauce   950-1,383
Soy sauce    800-1,300
Tomato paste 680
Cured ham    337
Anchovies/sardines   280
Beef 107
Cheddar cheese   78
Worcestershire sauce 34

Rich In Nucleotides
(MG/100 G)

Anchovies/sardines   193 (inosinate)
Dried shiitake mushrooms 150 (guanylate)
Pork 122 (inosinate)
Beef 107 (inosinate)
Dried porcini mushrooms  10 (guanylate)
Comment: I don't find umami flavors to be sharp or acidic at all.  The  characteristics the OP is describing are usually associated with the flavor "sour".
Comment: It's possible that cheddar has more umami as it ages but this isn't the flavor I'm referring to. Parmigiano is a good example of a cheese with a lot of umami. The taste I'm talking about seems unique to a subset of cheeses including cheddar. It may be less true for non-American cheddar, but aged American cheddar has a sort of aggressive flavor. It's hard to describe which is why I asked the question.
Comment: Ok gotchya. Understood.


How can option seller lose unlimited money?

Question: I hear that option seller can lose unlimited money, but how can option seller lose more than he deposited as margin?
Does he only lose the margin he deposited to sell option or unlimited?
Please clarify.
Comment: If you need to ask this question you should definitely not consider any option trading. It's extremely risky
Answer: Let's say I buy an option to buy 100 shares in company A at $1 next month.
Someone sells that option to me, the option seller. They presumably think the company A's share won't appreciate much.
Something extraordinary happens and company A's shares price becomes $1000 or even more at the time the option excise date, there's really no limit to the price a share may reach. Perhaps it's a mining company and they unexpectedly dig up a number of huge diamonds for instance.
I as the buyer of the option choose to exercise my option and buy my 100 shares, paying $100 for them.
Somehow the option seller needs to provide those shares, no matter what price they are now.
Generally your broker won't let things get that bad, they will send you a margin call. If you don't pay that, they will likely close your position and/or sell off any other assets you have with them.
If all that doesn't work, your broker could sue you for the money you still owe. The courts have various means to try to enforce eventual repayment of your debts.
Comment: @User65535 -- the point is that there is no limit in the transaction on how much the seller could lose.
Comment: @User65535: can lose all you have and carry the rest as unpaid debt until you declare bankruptcy and hopefully have the debt wiped out.
Comment: But no one has unlimited money, so no one can lose unlimited money?
Comment: Hilmar: It can also wipe out someone's life savings, or force them to sell their home.
Answer: The potential for unlimited losses refers to the option payoff, i.e. market price - strike for a call option. Since there's no limit to how high the market price can go (you could look at Bitcoin, Tesla, or even Amazon as examples), the loss to the option seller is theoretically unlimited.
Contrast that with a short put option, where the loss can still be devastatingly large albeit limited since the stock price is floored at zero.
In practice, you'd get a margin call as soon as your account value drops below the margin requirement, as Robert mentioned.
Answer: There is theoretically unlimited loss on any position that represents short the equity position, either direct or derivatively.
The most obvious way is a naked call.  The higher the underlying goes, the more the naked call loses.
The second way is a much more unusual and is a bit more complicated:
Exercise By Exception is an OCC rule that states that equity options that are one cent or more in-the-money (ITM) at expiration will be automatically exercised. If you are long the option, you can designate to the OCC via your broker that you do not want your long option to be auto exercised (not applicable to option sellers).
Regular hours market trading ends at 4 PM EST.  On the expiration date, options can be exercised until 5:30 PM EST.
A long put gives you the right to sell the underlying at the strike price any time until expiration. If it is out-of-the money at 4 PM and the something causes the stock to drop before 5:30 PM and the put goes ITM, it's likely to be assigned and you'll end up with a short position in the underlying.  The resulting short equity position now has directional risk (as an exaggerated example, think FDA drug approval announcement).


I have a '67 Camaro 350 with a starter that will not work when hot

Question: When the engine is hot the starter it will not work. When I run a wire from the battery to the neutral safety switch it starts. Also, after it cools down it starts.
Comment: Have you tried a different starter?
Answer: Most common problem those years, usually it is a wiring issue, wiring to solenoid start terminals gets burnt near the starter where it is close to the exhaust manifold. also the ignition switch gets burned out, check the switch and connectors for indications of over heating (burned). If there is no soleniod heat shield on the starter this can be the root cause, install a heat shield linked below, but check the wiring also.
Check the wiring for fatigue and burns near the manifold, repair as necessary.
Also you have to check the entire starter solenoid circuit path from the fuse box to the starter for problems. Fuse box >ign switch> neutral safety> starter solenoid, look for overheating of the terminals and wiring.
Also install a "new" starter with solenoid heat shield.
Stock starter heat shield below.
http://www.camarocentral.com/1967_1981_Camaro_Starter_Solenoid_Heat_Shield_p/alt-61.htm
Answer: I agree with much of what Moab wrote. Often times when a car gets to the age this one is, all of the connections get worn or dirty and have more resistance than they should. Add heat to a starter, and low voltage won't make the starter solenoid engage. After installing the shields stated above, if it still gives you trouble starting hot, you could wire in a relay that will allow for more voltage to get to the solenoid "exciter" terminal. This will by pass the connections so that the power comes from the battery, through the relay, to the starter. Less connections, more voltage. A three or four pin relay, some spade terminals and a couple of ring terminals, and some 10 gauge wire is all it takes.
Three pin: grounded through the body of the relay, so it must be bolted to the body of the car, the small exciter wire from the starter goes to the coil/engage pin, battery power from the battery terminal goes to one of the other terminals, and run the other terminal from the relay to the starter terminal.
Four pin: same as above only you have to make a ground wire to the 4th terminal, going to a ground on the body or engine.