Can I (an Illinois high school student) get a Seal of Biliteracy for Old Norse?

Question: I don't want any feedback on why I want Old Norse, I just want to know if it can be done.
Comment: Meta question: https://languagelearning.meta.stackexchange.com/questions/612/are-questions-about-language-certificates-on-topic
Comment: If the school system won't approve a dead language, perhaps they would accept Icelandic.
Comment: This is a really interesting question. *Some* educational institutions will allow you to choose *any* foreign language to meet a foreign language requirement if you can find an expert who is willing to test you in the language and write a report to the school on your progress.
Answer: According to the Seal of Biliteracy FAQ, Illinois is one of the states that "have approved a statewide Seal of Biliteracy". See also the Illinois State Seal of Biliteracy.
Since the Seal of Biliteracy is for any student who masters academic English and "any other language" (according to the FAQ), it is possible in theory to get a Seal of Biliteracy for English and Old Norse.
However, the State of Illinois or the school where you study needs to have implemented or recognised criteria or a language certificate for Old Norse. The Seal of Biliteracy website has samples of criteria from several schools in California. The Illinois State Seal of Biliteracy has a list of assessments in English and other languages; this list does not mention an assessment for Old Norse. According to the document about other assessments, a " school district that chooses to use an assessment to measure foreign language proficiency that is not included on the list shall maintain evidence that the assessment meets the following criteria:"

"Standardized assessment" is one that is available for use on a statewide or national basis and meets generally accepted standards of fairness, validity and reliability as stated in "Standards for Educational and Psychological Testing" (2013), published by the American Educational Research Association, and
"Intermediate high" as defined by the ACTFL Proficiency Guidelines 2012, published by the American Council on the Teaching of Foreign Languages; or for the American Sign Language, "intermediate high" is equivalent to meeting progress indicators for grade 12 set forth in the Standards for Learning American Sign Language (2014), published by the American Sign Language Teachers Association.

So all depends on the existence of such an assessment for Old Norse and the school district's willingness to recognise it.
However, a school district "may choose to also award the State Seal of Biliteracy through an alternative evidence method". Since an assessment that meets the above criteria is unlikely to exist, the way forward is to convince the school and/or the school district to adopt an "alternative evidence method" for Old Norse.


How do mutation and crossover work with real-valued chromosomes?

Question: How exactly are "mutation" and "cross-over" applied in the context of a genetic algorithm based on real numbers (as opposed to just bits)? I think I understood how those two phases are applied in a "canonical" context where chromosomes are strings of bits of a fixed length, but I'm not able to find examples for other situations. What would those phases look like on the domain of real numbers?
Answer: As @Thomas W said, you can be pretty immaginative when you're developing mutation and crossover methods. Each problem has its own caracteristics and, therefore, requires a different strategy.
BUT, from my experience, I'd say that 90% of crossovers and mutation on real numbers genotypes are solved using the BLX-α algorithm.
Crossover:

This algorithm is really simple. Given the parents X and Y and an α value (inside the range [0,1], generally around 0.1/0.15, but it depends by the problem), For each gene of your genotype:

extract the genes xi and yi
find the minimum and the maximum values
the new gene will be a random number in the interval [min - range * α, max + range * α]

A variation of this algorithm is the BLX-αβ, in which we take into account which parent performed better and use two constants (α > β) to increase the probabilities that the new value will be closer to the one of the fittest parent

Mutation:
With the mutation the situation is similar: we need to get a random value that is related to our problem domain (we do not want the mutations to be destructive! They have the function of exploring the space).
In these cases it is useful to determine a range for the mutation and use that range to find the new value of the gene using BLX-α.
A more sophisticated mutation algorithm can be achieved using BLX-α on boundaries that depend on the actual value of the gene and the fitness function of the individual.
Let's imagine that our individual performs in a very bad way; in that case the mutation operator will be used to shift the individual to a distant point in the search space, where it will probably perform better.
On the other hand, if the individual is already fit we may not want to introduce some dramatic changes using the mutation. In that case the mutation range would be more contained and would have the function of tuning the genotype instead of exploring for better alternatives.
Comment: Is it correct to say that with the BLX-α algorithm we can move to points outside the interval of the initial population? That is, assuming an 1d optimization problem, if the values for the initial population were in $[a, b]$, by applying the BLX-α we can move to a point in $[c, d]$ where $c > a$ and $d > b$?
Comment: @adosar The whole point of the BLX-α crossover (and most of the crossover algorithms) is to produce a result that is in the range of the parents' genes. So, although the new range is an extended version of it [a-α, b+α], you still want to explore the local space, rather than displacing yourself in a different point. If you were to choose a high value for α, you might move away from the initial population interval, but that will probably be counterproductive, as genes of individuals that performed well won't be passed down easily to the next generation. Short answer: no :)
Comment: It is a tradeoff between exploration and exploitation I think. It is not bad idea per se to move away from the initial population. Of course, we should somehow exploit the ``strength" of the parent genes so we can't set a very large value of $\alpha$.
Comment: @adosar yes you are correct. If what you care about is to diverge from the initial population, you can set an initially high α, that decreases over time. I don't really see the point of doing so though, you could simply spread it more when it is initially generated. After all, a good initial population is nicely spread over the whole exploration space
Answer: You have a genome with certain genes:
genome = { GeneA: value, GeneB: value, GeneC: value }

So take for example:
genome = { GeneA: 1, GeneB: 2.5, GeneC: 3.4 }

A few examples of mutation could be:

Switch around two genes: { GeneA: 1, GeneB: 3.4, GeneC: 2.5 }
Add/substract a random value from a gene: { GeneA: 0.9, GeneB: 2.5, GeneC: 3.4 }

Suppose you have two genomes:
genome1 = { GeneA: 1, GeneB: 2.5, GeneC: 3.4 }
genome2 = { GeneA: 0.4, GeneB: 3.5, GeneC: 3.2 }

A few examples of crossover could be:

Taking the average: { GeneA: 0.7, GeneB: 3.0, GeneC: 3.3 }
Uniform (50% chance): { GeneA: 0.4, GeneB: 2.5, GeneC: 3.2 }
N-point crossover: { GeneA: 1, | CROSSOVER POINT |  GeneB: 3.5, GeneC: 3.2 }

You can be pretty imaginative when developing mutation and crossover methods.


Can the current British monarch be overthrown or otherwise replaced?

Question: Having read a few discussions regarding the Plantagenets and the ascending line of the monarchy since, I became curious about whether another group/family had a 'more' legitimate claim to the throne (asked and answered, though not sufficiently in my opinion) or if another family could become the monarch. I don't want to base a question on an assumption, but I am curious all the same if by whatever manner the Windsors could be replaced - for lack of a more appropriate term.
Comment: This isn't about recent politics, unless the Glorious Revolution and the constitution are recent. Your actions are why so few new people post more than a few times.
Comment: There's a certain amount of 'finders keepers' about a throne. Even if they turned up some Plantagenet scion from the direct male line somewhere there's no reason to chuck out the Windsors and start with them.  If the Windsor line dies out then there will have to be some kind of scramble to decide which of several cadet families might then take over.  Perhaps they will make the current Doctor Who actor king.
Comment: Could they be replaced? Sure.  Constitutionally? unlikely.  Would they be replaced? Doubtful. They might be eliminated as surplus to need, but what would be the point?  They don't wield any power.  Might as well replace Emperor Norton.
Comment: @Oldcat: they already turned up [such a scion](http://en.wikipedia.org/wiki/Michael_Abney-Hastings,_14th_Earl_of_Loudoun). Ironically, he was a republican!
Comment: Should be noted that the British have replaced a king (Edward VIII) for completely trivial reasons as recently as 1936, although with another of the Windsors.
Comment: Why, are you aiming for their throne? :)
Comment: I'm not sure that any other family could have a more legitimate claim than the Windsors.  I think the Glorious Revolution settled the issue.
Comment: I believe it is on-topic as part of British constitutional history and/or it might also be appropriate for the law site as the OP deals with British constitutional law. The two overlap! Then there's always 'Right of Conquest'!
Comment: Mark, I would -1 both comments, and flag the last as innappropriate, if I could. Given the complexity of many of your previous posts, I expected better from you. Basically, you are saying that the Windsor family will remain the monarchy indefinately because of the constitution?
Comment: Perhaps I still don't understand the question. The Glorious Revolution established the British constitutional monarchy and identified the predecessor of the House of Windsor as the ruling family. The abdication of Edward VIII was a minor spot of trouble, but the constitution survived intact.  The only thing that I could think of that would eliminate the Windsors is if all the living Windsors decided to be celibate, but I'm confident the King Herald already has a plan to deal with that problem.
Comment: You are leading me to research the Glorious Revolution and the constitution that suppors the Windsors as the monarchy. Do you have any other suggestions? As you see, I don't know the composition of the constitutional monarchy or why the Windsors have the most legitimate claim to the throne. Your above edit clears some of this up.
Comment: Inevitably, Wikipedia has [an article on this subject](http://en.wikipedia.org/wiki/Alternative_successions_of_the_English_crown).
Comment: Can one be executed for treason for asking questions like this?
Answer: Today the British monarchy is an almost entirely ceremonial position. All the real political power in the country is invested in Parliament (mostly the House of Commons) and the court system. The Queen is left with only the ceremonial "Head of State" duties that in the US are performed by the President (or more often in fact delegated to the First Lady and/or the Vice President). Greeting foreign dignitaries, attending state funerals, etc.
For this reason, frankly there's no real incentive for anyone to try to change things in the violent manner that would typically be implied in an "overthrow".
Parliament can however, and in fact often does, pass laws changing both the personal requirements for a monarch, and the succession requirements. This generally has to be coordinated with the other dominions to avoid inconsistencies. This was most recently done in 2011 to allow for a fully gender-neutral succession. It would similarly be in their power to depose an unacceptable monarch (as was effectively done in 1936).
The most likely scenario for any kind of radical change though (and probably still not very likely) would be an abolition of the monarchy altogether, with the Head of State position becoming an elected one (or perhaps selected by Parliament). This gets discussed a fair bit in England particularly whenever any personal problems of Royal Family members make news, but support for that idea recently seems to bump around between only 15%-25%.
Comment: @Levi: For the most part it already **does** belong to the country, and is loaned back for use of the Royal Family. There are some exceptions but I am not up on the details.
Comment: The *Queen's* power to veto bills is done entirely on the advice of her Prime Minister (in other words, it is a government power masquerading as a Crown one). She does not independently exercise it. The Duke of Cornwall (Charles)'s power is not exercised on advice and is something he does use for himself. So it is right to say that the monarch has essentially no non-ceremonial role, but that doesn't mean that conclusion extends to her family.
Comment: Because the term abolition was brought up, what would happen to the royal families wealth? Would this revert back to the country?
Comment: The assertion that the role of the British royal family is largely ceremonial and of limited power does not stand scrutiny.
Members of the Royal family exercise power in order to protect their interests against the interests of parliament. http://www.theguardian.com/uk/2013/jan/14/secret-papers-royals-veto-bills The Royal perogative provides extensive powers for the Roayl family. http://www.independent.co.uk/voices/time-to-change-the-rule-royal-prerogative-is-an-unaccountable-power-that-must-come-out-from-behind-the-throne-says-jack-straw-1414386.html
Comment: 6+ years on. QE2 has immense real power, albeit usually immensely subtly exercised. I'm not going to start to rtry to justify that with any references - just note that if you start from that point of view and see if you can find how things would or could be different then   you'll find much to think on. Even something as trivial as the Royal 'honours system' which was introduced to include acknowledgement of the "common man" withing a preserve previously reserved for 'nobility' has an immense effect. Recommended by others? Sure. But the Queen makes it work and without her it loses its  ...
Comment: ... world class status. || Interesting data point: The Queen (by way of her representative) once 'unilaterally' dissolved the Australian parliament. To the utterly immense surprise of many.
Answer: Note: I don't think that what I'm going to offer is a particularly good answer, but I think it is a worse comment.
I think the key to the answer is the Glorious Revolution in which England expelled James II and invited William and Mary to rule England.
The legal basis for the crown is the 1701 Act of Settlement, which I missed, but @Spencer caught - hat tip to @Spencer
Aside:  @Oldcat's comments on the Young Pretender and the Old Pretender are very pertinent.   I approach the question through the lens of an American fascinated with British Constitutional evolution in the period.  I think that @Oldcat's comment is probably closer to the OP's actual intent.  For me, the British Constitution prevents any pretender from having a legitimate claim on the throne.
Although the Glorious Revolution is vital to understanding Great Britain, in my opinion it isn't the actual event of the Revolution, but the events of the following years that really define the British Constitutional Government.  I'd recommend starting with Edmund Burke Who is brilliant, but not easily quoted or summarized. With respect to the current question, I think that Reflections on the Revolution in France is vital, and I believe that Thoughts on the Causes of the Current Discontents may also be useful. I actually haven't looked at this question in a couple of years, but I believe that the (British) Bill of Rights of 1689 is probably important.  Essentially Burke argues that the English invited William and Mary to rule only after James II had invalidated his rule, and that the English agreed to be bound to the rule of William and Mary. He is quite adamant that unlike the French, the English Constitution is not based on a social contract, and that the English don't have the privilege of selecting Monarchs willy nilly.
Updated aside:  I haven't researched this period for about five years. I remember finding a paragraph from Burke that I thought summarized the question admirably (once I decoded Burke's prose).  I'm truly frustrated that I cannot find that quote anymore  (I've begun to wonder if it was not Burke, but someone else, but I cannot remember).

″Our political system is placed in a just correspondence and symmetry with the order of the world, and with the mode of existence decreed to a permanent body composed of transitory parts; wherein, by the disposition of a stupendous wisdom, moulding together the great mysterious incorporation of the human race, the whole, at one time, is never old, or middle-aged, or young, but in a condition of unchangeable constancy, moves on through the varied tenour of perpetual decay, fall, renovation, and progression. Thus, by preserving the method of nature in the conduct of the state, in what we improve we are never wholly new; in what we retain we are never wholly obsolete.″ Reflections on the Revolution

If you're looking for a good overview, I would suggest Mike Duncan's Revolutions podcast and website - he covers the English Civil war fairly well. Although the Civil War is distinct from the Glorious Revolution, I understand the Glorious Revolution better for understanding the Civil War.
I also recommend @Kobunite's answer summarizing the effect of the Bill of Right. I think Kobunite's summary of the various clauses is clear, helpful and accurate.  I wish I had the skill and the knowledge to explain why it is difficult for a modern reader with a modern reader's understanding of constitutional theory to read the Bill of Right and understand the assertions.  Modern readers rely on assumptions and concepts that were formed as a result of the Bill of Right; the contemporaries didn't have that advantage.  Quite frankly the analytical summary that Kobunite provides is (a) why I find the period fascinating and (b) part of what makes this period so vital to the understanding of the American government.
Comment: Interesting all around. I will review the provided links - thank you. This provides a lot of back story regarding the not so simple answer to my question. Basically, if I showed up on the doorstep tomorrow with a more legitimate claim to the thrown no one would care. It's too late.
Comment: @Oldcat - Queen Victoria WAS Hanoverian - she was George III's only (surviving) grandchild. And the Hanoverian succession was made necessary by the fact that Queen Anne's only child predeceased her, ending the Protestant line of the Stuart dynasty, and raising the spectre of a return of the Catholic Stuarts - which was unacceptable to Parliament and people.
Comment: Well, look up the Old and Young Pretenders (Stuarts) who hung around in France with a more legitimate claim to the throne for a few generations and got some free housing in exchange for the occasional invasion.
Comment: Once they decided they didn't like living without a king of some kind and they restored the Stuarts Charles II and James II.  When James' creeping Catholicism creeped them out, they tossed him and chose Mary (a relative) and Anne.  Even before Anne's death they knew that the German Hannoverian line would succeed her.  Queen Victoria was the solution when that line ran out.
Comment: Terse, not inaccurate, and somewhat amusing. But I'm not sure it helps those who aren't familiar with the players, and it conceals oh so much wonderful fascinating politics.
Answer: The current monarchy in the United Kingdom is very attuned to the public relations between that monarchy and the people of England (yes, and I mean only England).  Other public relations behaviour is far more muted in comparison.  This responsiveness emerges from a number of public relations disasters, including the monarchy's German heritage which caused the formation of the House of Windsor itself (https://en.wikipedia.org/wiki/House_of_Windsor#Foundation).
This sensitivity to the public is probably due to 20th century incidences of dethronement in Europe after mass public unrest, generally leading to a parliamentary republic, occasionally and briefly leading to systems of workers councils.  This, at least, is the animating threat that lies behind the the House of Windsor's activity, service to the nation, etc.  I would suggest that fear from the Windsors indicates at least one viable method of removal, within or without the constitution: mass public outrage which either parliament attends to, or which also destroys parliament.
To belatedly expand, Graves and Hodge's The Long Week-End: a social history of Great Britain 1918-1939 not only notes the general strike, but also that the British republican flag was displayed in 1935 during Edward's unwillingness to conform.
Comment: Samuel, I think your post deserves an upvote, but I cannot do so yet. Very insightful response.
Comment: *"British republican flag was displayed in 1935 during Edward's unwillingness to conform."*  But at Edward's abdication, people also sang "Hark the herald angels sing, Wallis Simpson stole our King!" ;-)
Answer: I can envisage a perfectly valid scenario for the abolition of the British monarchy - although an unlikely one.
A radical republican government is returned to power with an overwhelming majority. It passes a Bill to abolish the monarchy and replace it with an elected President. Now, it is not law until it has received the Royal Assent, and the sovereign is not bound to grant it, merely expected to.
If the sovereign refuses her/his assent, the Government resigns, triggering a General Election. The result is  the same - a huge majority for the republicans. In theory the monarch could ask anyone in Parliament to form a Government, but this would almost certainly not work, given the size of the (now) Opposition). No legislation would be passed, a vote of No Confidence in the Government would be passed, triggering yet another General Election. The British are generally slow to "man the barricades", but even they would probably be driven to it by then.
It is, therefore, far more likely that the sovereign would accept the will of the people, expressed in Parliament, and sign the Abolition of the Monarchy Bill into law, thus abolishing her/himself.
With British pragmatism, all this would be accompanied by (probably secret!) discussions as to the terms of the royals' departure - financial arrangements, leave to remain in/return to the UK, agreements preventing any "Pretenders"  later challenging the law etc. It is an unlikely, but perfectly possible scenario.
The only main difficulty I see is in the beliefs and views of the current Queen. She is devout, and genuinely believes herself called by God to fulfil her role, for life. She might regard agreeing to the abolition as a breaking of her Coronation Oath. On the other hand, she is reputed to have said in the past that they "would go quietly", if asked.
So yes, it would be constitutionally possible to abolish the Monarchy. It's just not going to happen, at least any time soon.
Answer: Well, the monarch holds that position at the pleasure of Parliament. The constitutional way to replace the monarch is to persuade Parliament, and a sufficient fraction of the population, that installing you as monarch would be to the national advantage. The limited role of the monarchy, and its long tradition and popularity make this impractical at present.
Even if you could persuade P&tP that the monarch should go, convincing them that you'd be a better idea than the abolition of the monarchy would be very hard. The British are quite aware that the monarchy is an anachronism and somewhat silly, but as of 2018 they prefer it to the alternatives, largely because of the perceived qualities of Elizabeth II. I anticipated an upsurge in republicanism after her death, but I appear to have been wrong about that.
Seizing the crown by small-scale force would be futile. P&tP would take no notice of you, and would rally to whoever was the surviving heir. There are at least 5,000 descendants of Sophia, Electress of Hannover, so there would be an heir, although sorting out who it was might be tricky. In any case, you'd be arrested or killed by the military.
If you were able to start a full-scale revolution (difficult, at best) or mount an invasion, and by one of these means overthrow the whole governmental structure, you could establish a new one with you as monarch, but hanging onto the position could be hard work. We did revolution in the 17th century, and we didn't like the results.
If only you want to acquire the use of the monarch's powers, that's more practical. One way is to marry someone who is in line for the throne, and allow time and a few staged accidents to do their work. Your best bet would have been to marry Prince Harry, and arrange for an accident for his elder brother and his descendants. As time has passed, there aren't any good candidates for this stunt at present. There is no way to acquire the throne for yourself via marriage.
However, the easier way to acquire the use of the monarch's powers is to become Prime Minister. This is completely legal, doesn't require violence, and can be accomplished in about 20-30 years of hard work in the bowels of British politics.
Answer: The law of succession has always been open to some interpretation. See this mess here: https://en.m.wikipedia.org/wiki/Alternative_successions_of_the_English_and_British_crown. Making up some codswallop about how your guy was the 'real' king was what you did if you didn't like the current one.
In principle, no law can be passed without royal assent. The convention is that it's waved through without the monarch even being physically present. However conventions are not enforceable in the courts, so if a monarch really didn't want to sign a law, who knows?
The closest Britain has come in recent times is Edward VIII. His government, for several reasons, threatened to resign unless he abdicated. He folded. If he hadn't, he might have faced a revolution, but legally there would have been no recourse whatsoever.
Comment: Two points worth noting: 1. the last time that Royal Assent was refused was by Queen Ann when she refused assent to the [Scottish Militia Bill](https://en.wikipedia.org/wiki/Scottish_Militia_Bill) in 1708. 2. HM armed forces still swear allegiance to the Crown, not Parliament. All part of the "checks & balances" put in place after Cromwell's use of his New Model Army during the Commonwealth.
Comment: Yep, they haven't refused royal assent for a long time. But so what? We're learning in modern times that if someone wants to ignore legally unenforceable values, they sometimes get away with it. I can't see the Windsors pulling the same kind of stunt, but that's just good luck. Maybe one day a less scrupulous scion of the Windsor family will give it a try, and then we'll find out what the oath really means. I hope not.
Comment: I think you miss my point. There is precedent for exercising the Royal Prerogative and withholding assent. Were the monarch to do so, it would presumably be referred to the courts. If Parliament were then to attempt to enact legislation in defiance of the withheld assent (and any court ruling), the army could intervene (presumably to force the dissolution of Parliament, and force a General Election). It is known as "duties in support of the civil power".
Comment: Well, that's just it: there is no statute saying that the Monarch must give assent. So, what law has the king or queen broken if they exercise their veto?
Comment: Is this really an appropriate historical question?


set up electronic drums in ableton

Question: So, I have Alesis DM Lite electronic drum kit and I also have Ableton Live 9 software. I want to record the drums thorugh Ableton, but I don't know how to set up the drums in the software. The drum kit has a usb port with one end which is like the one for printers (not the regular usb end) and with that I can connect the kit to my computer. When I open ableton it detects that the drum-kit is connected, but I can't make any sounds with it whatsoever. Can someone please explain how to set up the drums in ableton so that it reacts to the signals when I hit the pads?
Thanks! I hope you got the idea.
Comment: Do the instructions not talk you through the process?
Comment: If you have time, can you tell us if you are familiar with MIDI or have any experience with MIDI recording and playback?
Comment: Todd Wilcox, sorry for such a late response, I hadn't noticed that you had commented. No I don't have any experience with MIDI at all.
Answer: you need to learn about the basics of ableton live.
first of all, you need to understand drum rack basics.

then you need to understand the MIDI input and output basics in ableton live

or

actually, the simplest way to explain why you're not getting sounds is you did not insert any instrument to your armed monitoring MIDI track.
hope this helps.

set up electronic drums in ableton


Is BKB50 keyboard touchpad for Sony Xperia Z4 compatible with any RDP client?

Question: As you know - Bluetooth keyboard BKB50 was designed for Sony Xperia Z4 Tablet. The keyboard has an integrated touchpad that controls the mouse on device's screen. With help of some RDP terminal clients I want to connect to my Windows desktop.
Will mentioned keyboard touchpad help to control mouse within RDP session? Which RDP client to use to be able manipulating the mouse by BKB50 keyboard touchpad?
Answer: Yes. Examined with Microsoft RDP client.
Comment: Could you elaborate a bit more on the point? Perhaps include a screenshot of it working? Any other RDP clients it is compatible with?
Comment: Unfortunately snapshot will show only Windows desktop (poor proof). Is there any way to attach video to the answer without violating site policy?
Comment: You can link to YouTube, no problem, as long as you attribute it properly. But a proper screenshot is enough.


Esp32: upload eeprom file

Question: I'd like to flash the eeprom sector with content so that the eeprom already holds data when it boots the first time.
How do I upload such an eeprom file like I would do with avrdude on an atmega? Is there a tool that can be installed in the arduino IDE like the data uploader?
Comment: esptool can download and upload any region of the esp flash
Comment: @Juraj I can't find any dedicated command line option. Like, for my atmega I would use something like `-U eeprom:w...`. Do I have to find the address offest myself and if so, where? Actually, where do I find the actual partition table the arduino IDE uses?
Comment: I said "flash". the esptool command is read_flash and write_flash. I don't write an answer, because I never tested that.
Answer: The ESP8266 has no EEPROM.
Instead the flash memory is partitioned into different areas for different purposes. One of those areas is set aside for "EEPROM Emulation" data.
To upload to that area you first need to know where that area is in the flash memory, and that is dependent on what partitioning scheme you are using at the moment.
Once you have worked that out (look in the partition scheme files in the core for more information) you can then use esptool to upload data to the right area of flash.
Comment: @Juraj I did, yes, but technically I am also correct saying it has no flash, since it relies on an external flash chip :)

Esp32: upload eeprom file


Who were Esav's wives?

Question: Bereishit (Genesis) chapter 26 and Genesis 36 state different names for the wives of Esav (Esau). What are the different explanations to this problem? (Biblical Criticism explains this as two different traditions.) What are the traditional explanations to the problem?
Answer: There are basically two lists of wives and each one contains 3 names. Traditional sources differ on exactly how to answer the contradiction, with the opinions ranging from Esau having 3,4,5, or 6 wives all together. See http://jbq.jewishbible.org/assets/Uploads/424/jbq_424_Kleinwivesofesau.pdf for an article which summarizes these views.
Comment: Summary of the paper:
`Rashi takes them to be the same women listed under different names. Sefer ha-Yashar and others maintain that Esau had four wives, since they refuse to identify Judith and Oholibamah as the same woman. Nahmanides mostly agrees, with the caveat that Adah daughter of Elon the Hittite and Basemath daughter of Elon the Hittite were not identical but sisters. In his view, therefore, Esau took five wives. Abraham Maimuni utterly rejects the notion of the Bible mentioning Esau's wives under different names. His explanation is that Esau had a total of six wives.`
Comment: Ok, so I suggest you read the article I linked to.
Comment: I have never seen a suggestion of him having more than 3, just they had pseudonyms and the Basemath in each case is a different one which makes it more complex. 2 were hittite women and the other was the daughter of Yishmael.
Comment: That is interesting. I am curious as why Rashi describes the daughter of Yishmael as "another unsuitable wife". I don't know how righteous she was and obviously she didn't reform Eisav but her heritage seems fine..

Who were Esav's wives?


Electrolysis not running, maybe dependant on distance of electrodes?

Question: So I created a DC power supply of 15 V (special transformator connected to the net) and I have a graphite anode and stainless steel cathode. When I put them in a beaker next to each other in water, the electrolysis takes place as I see gas bubbles. However, when i put them in another container that consists of two beakers connected with a tube to allow liquid to flow through but to separate the gases, the reaction doesn't run while it is the same setup more or less. How come? It is true that the tube connecting the beakers is relatively thin and the distance is also quite large (10 cm or sth), so does this lead to a higher required overpotential? I really don't know why it doesn't work in the larger container. Any help is appreciated!
Comment: **[Don't use stainless steel in electrolysis!](http://antique-engines.com/stainless-steel-electrodes.htm)** Carbon electrodes are quite fine.
Comment: Adding a small amount of salt (or acid/base) will increase the conductivity of the solution and improve the rate of electrolysis.  This can generate side products, like small amounts of chlorine gas, as well, just FYI.
Comment: Yes indeed, I have read before stainless steel releases toxic chromates, but I only use stainless steel for the cathode as it is being reduced, not oxidized.
Answer: Solution resistance in a two electrode cell can make a big difference as it is totally uncompensated. You may be applying 15 V between the electrodes, but the redox reaction only occurs at a very close proximity to the surface (<10 nm), so it's the interfacial potential we're concerned with, which can be significantly different than the applied voltage if the solution is highly resistive. A tight constriction in the cell can certainly increase the resistance and you should make sure you're using an electrolyte as plain water is very resistive.
Answer: Resistance is proportional to length and reverse proportional to сross section of the conductor. When you increase distance by 20 cm from 2-3 cm (10 times resistance) AND indtroduce ion bridge about 1 or less cm in diameter (probably also 10+ times resistance, likely more), you effectively increase the resistance by several orders of magnitude, proportionally reducing the current and the speed of the reaction.
In industrial-grade applications when speed of reaction is of essence, like eletrolitic cutting, the distance between electrodes may be as small as several millimeters. Strong electrolite flow is also used.


How to extract specific frames/model from a multi model pdb file?

Question: I have a multi model pdb file and would like to extract the last frame or any other frame from it.
Answer: Do you have access to OpenBabel to run from the terminal?
For the purpose of demonstration, the example following is demonstrated on a file listing SMILES strings.  However, the concept may be applied on a .pdb with multiple models (and equally works well enough on multi-model .sdf).
The input file input.smi is a small set of aromatics.  SMILES strings and labels are tabulator separated:
c1ccccc1    Compound 1
c1(cc(cc(c1)C)C)C   Compound 2
c1(ccc(cc1)C)C  Compound 3
c1(ccccc1)C Compound 4
n1ccccc1    Compound 5
n1cnccc1    Compound 6
n1cncnc1    Compound 7

My interest is on the p-xylene only (i.e., Compound 3).  With the instruction
obabel -ismi input.smi -f 3 -l 3 -osmi -O interest.smi

OpenBabel anticipates the input file to contain SMILES (-ismi), starts processing with the third model entry onward (-f 3, line/model counting index in the file starts by 1), accessing all entries up and including the third one (-l 3) in this file.  The output, to contain SMILES and their labels (if present) is formatted (-osmi) and written permanently (-O) into file interest.smi which eventually contains
 c1(ccc(cc1)C)C  Compound 3

Since OpenBabel run from CLI is agnostic about file extensions, your processing of .pdb to be read, and to be written requires an adjustment of the input/output parameters e.g., in the pattern of
obabel -ipdb input.pdb -f 3 -l 3 -opdb -O interest.pdb

This approach equally allows to extract a contiguous set of entries, e.g.
obabel -ismi input.smi -f3 -l5 -osmi -O interest.smi

to process 3 molecules at once.  The toggles -f and -l may be used independently of each other, and spaces between them and their then mandatory integer parameters may be omitted.  The approach however is unable to pick a set molecules in the mixed pattern like (1, 3-5, 7).
Said selection may be achieve from obgui, too:
Answer: file=test.pdb #pdb file
frame=10 # frame number to extract
x_frame=$(egrep "MODEL.* $frame$" $file)
sed -n "/$x_frame/,/ENDMDL/p" $file > ${file::-4}_frame_$frame.pdb

output file will be written as filename_frame_10.pdb

The bash script below provides easier (repeated) access to the functionality described:
#!/bin/bash

# Extract a specific .pdb from a multi model .pdb file

# Save this bash script as pick_pdb.sh and run
#
# bash pick_pdb.sh test.pdb 3
#
# to write test_frame_3.pdb as new file.  Relies on bash and sed.

if [[ -z "$1" ]] ; then
    printf "Check how to use this bash script with
        bash pick_pdb.sh -h  \n"

elif [[ "$1" == "-h" || "$1" == "--help" ]] ; then
    printf "Export a specific model from multi model .pdb file.

E.g., to extract the third model from intput.pdb,

    bash pick_pdb.sh input.pdb 3

writes file input_frame_2.pdb.  \n"

else
    file="$1"
frame="$2"

    filebase="$(basename "$file" .pdb)"
    output=${filebase}_frame_$frame.pdb

    x_frame=$(egrep "MODEL.* $frame$" "$file")
    sed -n "/$x_frame/,/ENDMDL/p" "$file" > "$output"
fi

Comment: @Buttonwood could you please share the file?
Comment: thank you for catching this. I was grepping only ATOM section while babel has HETATM there. Removed the grep ATOM section.
Comment: Ok. Because I like your approach to call `sed` to extract *the* model of interest, a small re-usable bash script was written around your instructions. So autocomplete (of the file name) by the CLI and state the number of the model one is interested suffice. The repeated use *as such* (or, embedded into an other script past `chmod u+x pick_pdb.sh`) like `./pick_pdb.sh input.pdb 3` offer the results quickly with little typing only.
Comment: @Buttonwood , Fantastic :), thank you
Answer: You can use the Python script multiple_model_PDB_file_splitter:
# multiple_model_PDB_file_splitter.py by Wayne Decatur
# ver 0.2
#
#*******************************************************************************
## PURPOSE: Takes a formatted pdb file with multiple models and splits each model
# into individual files. Requires the PDB file include both MODEL and ENDMDL

# records for each of the models.

# Originally developed in Python 2.7, but confirmed to work in Python 3.6.
#

You can download it from here.
Other useful script from the same author can be download here.


New to Fate: how to manage all aspects at play

Question: Newbie Fate GM here, I will soon GM my first ever session. Seeing how important being aware of all aspects at play at any given scene is, how do you keep track and announce all the various aspects currently at play? Do you use post-its? Hand out sheets of paper? Enumerate loudly and have players write them down? I feel I may lose track of all the aspects at play, and my players too...
Answer: Index cards are the canonical tool (what the book suggests). It's not the only way.
They're easy to pick up and get rid of when one of them stops being relevant (the scene changes, someone Overcomes the Aspect and it goes away, etc).
I label them with "Scene Aspect", "World Aspect", or what-have-you. Some people use color-coded cards for that. For an Aspect on a character, something temporary, created by an Advantage action or something else, I typically still use an index card (labelled "Advantage") and clip it to my copy of the character sheet (instead of writing it on their sheet, since it's temporary: usually lasting for the scene, definitely less-than-a-session).
You can do this with post-its instead, or with a list on lined paper, or with some digital tool. They would all basically work the same way.
What I lose track of more frequently than the actual Aspects are the free-invokes which may have been gained on them, and whether they have been used up or not. So I put squares on the index cards and check them off as the free-invokes get used.
I also actively coach players to not-forget that there are Aspects on the table and that they should maintain some amount of awareness of them. Or, more precisely, their characters should (in-character situational awareness). One way I do this is to repeatedly refer to them in my GM patter. Another is with out-of-character nudges.
Answer: I actually prefer Post-It notes to index cards when I play FATE in person. Post-It Notes and some way of tracking FATE points and free invokes, like M&Ms or spare dice that I might have left over from some other game we're not playing at the moment. When you're playing in person, this has the added bonus that everyone sees you scribbling a Post-It out and slapping it on the table so there's no confusion as to whether or not they can use it.
The advantage of them, I think, is that index cards just seem more, I don't know, permanent. Nobody cares if you crumple up a Post-It when it no longer applies, but you actually have to collect and pile up those index cards (and I do actually use these myself, but generally when I'm making fractals rather than situational aspects).
Answer: I play on roll20, so my advice may not fit for your table, but I create lots of little tokens and tags and objects for people to actually see.
The one time I've played it in person I used note-cards and just jotted stuff down and set them out on the table for people to see.


Regarding Sujud

Question: Salamu'alaikum.
Please is it permissible for someone to spend longer time in Sujud while the Imam had already gotten up? If no, kindly help me with the Hadith that prohibits that.
Jazakumullah Khairan.
Comment: Salam and welcome to IslamSE the Q&A site about Islam. To learn more about our site and model consider taking the [tour] and checking our [help].
Answer: Sahih al-Bukhari, Narrated `Aisha

Allah's Messenger (ﷺ) during his illness prayed in his house sitting,
  whereas some people followed him standing, but the Prophet (ﷺ)
  beckoned them to sit down. On completion of the prayer he said, "The
  Imam is to be followed. So, bow when he bows, and raise your head when
  he raises his head." (See Hadith No. 657 Vol 1 for taking the
  verdict).

Narrated that Abu Hurairah

The Messenger of Allah (ﷺ) said: 'The Imam is appointed to be
  followed, so when he says the takbir, say the takbir, and when he
  recites, be silent.'

Muwatta Malik

.... The imam is appointed to be followed as a leader, so do not oppose
  him.' Abu Hurayra said, 'The one who raises his head and lowers it
  before the imam - his forelock is in the hand of a shaytan.
Comment: Jazakumullah Khairan
Answer: You must follow the imam as else you may risk that you prayer would be invalid according the opinion of some scholars. Note that imam in Arabic means leader! The imam of a congregation leads the prayer.
The main reference are the ahadith which have been narrated on the authority of Anas ibn Malik (see in Sahih al-Bukahri 1, 2 3 and Jami' at-Tirmidhi), abu Hurrairah (see in Sunan ibn Majah and Sunan abi Dawod), Hittan ibn 'Abdullah (Sunan an-Nasa-i), 'Aisha (see in Sahih al-Bukhari and Sahih Muslim) and many more similar ahadith and narrations.
Imam an-Nawawi commented the hadith as follows:
 This is my own translation take it with the necessary care

وفيه وجوب متابعة المأموم لإمامه في التكبير والقيام والقعود والركوع والسجود وأنه يفعلها بعد الإمام
This hadith shows that the ma'umum is asked (wajib) to follow his imam, in his takbeer, standing, sitting, bowing and prostrating and that he has to do what the imam has done after the imam. (Source fatwa on islamweb #121568

Note that salat in congregation is a symbol of unity if you prolonged your sujud you would be like a misfit in the jama'a also it may lead you to riya' as you may come to the conclusion that you are more pious than the rest ...
There are ahadith on the opposite situation if a person for example stands up before the imam too.
In this fatwa on islamqa #33790 all the four cases that may happen to a ma'mum in a congregation prayer (Anticipation (doing a movement before the imam), Delay,  Doing an action simultaneously with the imam and Following) are discussed.
Comment: Masha Allah.  Jazakumullah Khairan

Regarding Sujud


Stuck outer bearing race in motorcycle wheel?

Question: I have the outer race of a bearing stuck in my wheel. I'm out of ideas to get it out, I have tried griding down to relieve the tension and let it pop out with no luck.
I have used a tonne of heat also to no avail.
I don't have access to a welder unfortunatley.
I think there is a tonne of corrosion in there, that's all I can think of, I have a blind bearing puller on the way which is big enough for this size although I don't know if it will fit under the bearing yet.
Any ideas on other ways that could get this out?
Cheers
Comment: I once removed a stuck front wheel bearing race by heating a section red hot and quickly quenching. It changed the temper of that section of the race into a brittle state so a blow with a ball peen shattered it. Removal of the entire race was easy after that. BTW, if you're trying to remove with heat, you should be heating the surrounding metal not the race itself. The surrounding metal will have a greater thermal expansion rate than the bearing race.
Comment: @Jeeped when you quenched, did you do the race itself? I have been heating the hub itself(it's aluminium). I use a heat gun as I don't have a blow torch. I have heated to the point the paint is bubbling and cracking/peeling( I'm not too fussed as the wheel needs re-painting ha). The highest setting I use on the gun is 650 deg C.
Comment: Yes, the second part of my comment may have made the first part confusing. If you are trying to make the race brittle, heat up a section of the race at least cherry red then thoroughly and quickly quench. The faster you can dissipate the heat the more you will chenge the temper. The second part of my comment was directed to your current practice of using heat to 'loosen' and remove the race.
Comment: I see, so if I was to heat a part of the race until it glows and then pour cold water over it I should be able to shatter it?Would this not compromise the ally hub in any way? I'm not fussed how I get it out as long as I can get a new bearing in there. Cheers
Comment: That's the method I used with success. Your own success will depend on many factors that I am not privy to. Heat as quick as possible then quench quickly and thoroughly. If done correctly, the sudden changes in internal stresses may even crack the race during the quench.
Comment: Cheers, I'll give it a shot although I don't think the heat gun would be fast enough.
Comment: No, not a heat gun but a hand held propane torch commonly used for soldering pipes should be sufficient
Comment: I use a mig welder, do a couple of tack welds in the center of the race, this will cause it to crack, which makes it much easier to remove.
Answer: Given the state of that then I would grind the other side and use a big chisel and matching hammer to crack the last bit -  always worked in the past.
Answer: Managed to get it out, Sorry for the late update.
Used a dremel with a better grinding tip and diamond disc. With a bit more patience the race finally gave. Thanks for the help all.


what would happen if port 22 and 23 are opened

Question:

what would happen if port 22 and 23 are opened
Comment: Ports don't have vulnerabilities. Applications bound to ports can have vulnerabilities, or protocols operating on a specific port can have vulnerabilities. Step 1 is identifying what is actually running on the ports, then look at vulnerabilities associated with that package or protocol.
Comment: Welcome to [security.se] Benz! Unfortunately, as it stands this question is far too broad for us to answer and thus I have flagged the question for attention. It would greatly help us and yourself if you could edit to include a specific problem you're facing. Viewing the [Help Center](https://security.stackexchange.com/help) will help you better understand the nature of the site and what questions you *can* ask - then we will be able to help you.
Answer: It mainly depends on what is listening on that ports.
However, just having the ports open mean that an attacker can interact with the TCP/IP stack of your machine.
Comment: I fail to see why the TCP/IP stack wouldn't just discard a packet on an unbound port.
Comment: I was doing information gathering with Nmap and did port scanning for an IP related to my application . The result displays that TCP port 23 was opened and several other ports . I was trying to figure out what would happen if these ports are open like DOS attacks can happen or Sniffing packets . I might be wrong Please correct me as I'm new to Network Pen Testing .
Comment: @M'vy What I understand is that that "discard" functionality means doing something with the packet, some kind of logic that finish with the TCP/IP Stack sending a RST, sending nothing or whatever. That "something" may have vulnerabilities. Not sure if I'm right and if this ever happened but I would like to listen other opinions.


Can summoned creatures wield magic weapons?

Question: Can a Pit Fiend summon from an Infernal Hexblade's Greater Summon Warlock's Ally pick up (or be given) a magic sword and use it (without proficiency) as a basic attack, like characters from any class can?
Comment: Related: [Can creatures in the Monster Manuals make melee basic attacks?](https://rpg.stackexchange.com/q/98482/33707)
Comment: @Glazius I finally got a copy of his sheet from the guy who helped him with the build. I've edited the question accordingly.
Answer: Summon Warlock's Ally creates a summoned ally with a very limited scope of actions.
It is not possible to pass a summoned pit fiend shadow a weapon, or have it use that weapon to make basic melee attacks. The Summon Warlock's Ally power states, in part:

The creature lacks actions of its own. Instead, you spend actions to command it mentally, choosing from the actions in the creature's description.
Heroes of the Forgotten Kingdoms, page 213

A pit fiend shadow is detailed on page 236 of the same book. It can make a melee attack as a standard action, a tail swipe to cover the warlock as an opportunity action, pulse its fear aura as a minor action, and walk/shift/stand/run/squeeze/crawl once a round as a minor action. These are all the actions available for the warlock to command it to use; it has no other actions.
There is no entry in the description that lets it take a melee basic attack, so it cannot. (It is described as wielding a weapon, but its melee attack has a fixed damage expression instead of using [W].) There is also no entry for many common actions that player characters could take, such as picking up an item or drawing a weapon; technically it can't even do things that require free actions, such as talking.
4E tends to very sharply delimit the use of powers, especially combat powers, extra-specially combat powers that summon another combatant. You're free to hack or otherwise make judgment calls; for example, I'd let any summoned ally take the escape action as a minor, which seems like an oversight.


Why does SNR have an impact on the bit rate?

Question: I have some confusion regarding the impact of SNR on the bit rate. For example, if I have a QPSK-OFDM system, then my bit rate will be 2bits mutiplied by the number of sub-carriers of the OFDM modulation over the symbol time. How can I account for the SNR in this case?
Comment: This is the *transmit* bit rate. At receiver, the better SNR, the lower reception error probability, thus the *expected correctly received* bit rate does depend on SNR.
Answer: Yes, try to understand what is the concept of SNR  and it depends on what. Then, it will be easier to understand why SNR and BER increase and decrease in all cases.
In your case, OFDM, the relationship between the SNR and BER is given:
$\textrm{BER} = \frac{1}{2} \left(1 - \sqrt{ \frac{L/N \times \textrm{SNR}}{2 + L/N \times \textrm{SNR}}} \right)$
Where $N$ is the number of subcarrier and $L$ is the channel diversity. $\textrm{SNR} = p/\sigma^2$ .. where $p$ is the transmitted signal power, and $\sigma$ is the variance.
so now, you check the relationship between the type of used modulation with the above equation, (QPSK and N) , it's easier to explore the behavior of BER. remember also that probability of error when using QPSK is different about when using for example QAM and so on
good luck


Why do I tend to fall backwards when squatting low?

Question: I have noticed that I can't squat ATG until or unless I hold onto something in front of me.I tend to fall backwards as soon as I tend to go parallel to floor or more.I do increase the depth if I hold a dumbbell I'm front or widen my stance.Is it a mobility issue and I think it's hampering my leg growth.
Comment: We can't tell you why this is happening without seeing it. Could be that you're not leaning forward to compensate. Could be bad ankle mobility.
Comment: Do you know of any online vid source that deals with this problem and demonstrate the correct way?
Comment: It's normal, and probably your ankles. Try sticking your arms out in front of you (no bar/weight, obviously), and sometimes that's enough counterweight. It just takes work. Deep squats and pistol squats help, check "frog" position as well. Knees tucked, elbows sort of on quauds, feet off the ground.
Comment: @EricKaufman yes sticking out my arms does give me depth,also I do struggle going hips parallel to floor in attempt to do a full pistol squats,I also feel tightness in hamstrings when trying to stretch my leg straight out front.
Comment: @sagnikdas keep doing full depth squats with good form (weighted), it will stretch you out quite well. It's really just a time thing.
Comment: @EricKaufman What do suggest about the stance width?I get additional depth if I widen up.
Answer: Probably a lack of ankle mobility. You can use weightlifting shoes to compensate it, but that won't fix the problem, just allow you to squat in a safe position with your current mobility
You should foam roll and stretch your calves. You can do deep squats for 2-3 minutes at a time focusing on your ankles (and add a plate or something under the front part of your feet to increase the stretch if you want to), and/or do that: http://myfiveminuteyoga.com/wp-content/uploads/2012/10/feet-to-bricks.jpg
Also make sure your ankles are warmed up before squatting, foam rolling, or stretching
Comment: +1. That's exactly what held me back at the beginning. I thought my ankle flexibility was good, but it needed to go further. Other than just doing squats (and trying to avoid relying on pulling too much on the object in front of me), I did deep lunges with the heel down and sat on a low stool with the ball of my foot on a towel, and alternated a deep flex and short pulses.
Answer: I'm working on building up my squatting ability right now — among other things — using body-weight exercises. BJ Gaddour has an excellent book that is super cheap via Kindle. It is called "Your Body is Your Dumbbell." That's what I'm using. For squats, he has you start out by squatting with your back against a wall. He teaches correct positioning, such as ensuring your feet are making three-point connection with the ground: heel, big toe, little toe. He also teaches how to make his exercises progressively more difficult. Really can't recommend his approach enough.


Alternative options for scheduled job queue?

Question: I really like using queues for interprocess communication. It's great to be able to spin up a ton of workers and be guaranteed that a job in the queue is only run once, is treated fairly, can be scaled horizontally, and can optionally expire if it is not handled quickly enough.
However, I can't seem to find a job queue implementation that also supports putting jobs into the queue at a specified time.
What's the best way to attack this problem? Does a queue like this exist?
So far my alternatives to such a queue are:

beanstalkd - supports delayed jobs, I could calculate the delta between now and the specified time.

imprecise: what happens on timezone changes, or really large deltas (months)

"at" command - create an at job that would spin up and put the schedule job in a queue at the specified time.

tied to a single machine: What happens if the system restarts? How do you port jobs to a new server? Single point of failure
manually handle expiration if you have a long downtime.

delayed_job/custom polling - create a daemon (something like delayed_job) that continuously polls a database of scheduled jobs and inserts into queue at the specified time

seems too complicated
Answer: Something like the Open Source Job Scheduler may be appropriate...


What should I do after I lost my MacBook data?

Question: I lost my data on my Mac and now I don't know how to recover it. Do I have to go to a recover shop and pay for the costly recovery?
Comment: How did you lose it - the correct answer is restore from your last backup but I would guess you do not have one?
Comment: yes, finally, i used a full version of minitool mac data recovery. i had to pay for it. it sucked.
Comment: Use Time Machine!
Answer: It depends on what condition the hard drive is in, if the drive is still at least partially working and can be connected and recognized by a computer, your in luck and you should be able to do your own recovery. Note that the drive does not have to be mountable it has to be able to show up in Disk Utility. If there was a mechanical or electrical controller failure with the storage drive then a recovery shop is the answer.
A Do it yourself solution if the drive is not dead

If you are using the drive to boot from, stop. Don't use the drive anymore until you have performed a recovery of the data.
If you don't have a external hard drive that you can boot from to do the recovery I recommend getting one, you can use it as your backup drive later. For now install SnowLeopard or Lion onto it, then boot up from it. Make sure it will be big enough to hold all the files you may want to recover including the size of OS X on the drive you are recovering data too.
Obtain a software recovery tool, I have used Data Rescue with great success several times in the past year. Additionally it is available at a great price Data Rescue at the Mac App Store, its cheaper since you can't recover from a hard drive you are booted from. This is not a problem, since besides one should not really recover onto a potentially failing drive or a drive where one accidentally deleted stuff.
Perform the recovery and save the recovered files onto your clean external drive you are booted from.
Recover and salvage whatever lost files you want to keep.
Answer: Try as MrDaniel has posted. In the future, make an investment if possible and take advantage of the features TimeMachine offers. http://support.apple.com/kb/HT1427 Let this be a lesson learned and allow for a simple fix in the future! :) Have a great day & good luck on the recovery!
Answer: If you have a backup, use Migration Assistant to recover your files from your Time Machine backup to a new user.
If you don't have a backup, you can use file recovery software to try and recover some of your files.
First, as described on another answer, stop using the computer with the deleted files right away.
Each time you turn on the computer, space marked as empty is overwritten -for cache purposes, local Time Machine backups, etcétera- and your chances of recovering your files diminish.
Then, put the computer with the deleted files on Target Disk mode and connect it to another Mac. On this second Mac, install recovery software. I've used TestDisk with success.
Other users recommend Disk Drill, which has a GUI, and may be easier to use.


Is there something similar to Noether's theorem for discrete symmetries?

Question: Noether's theorem states that, for every continuous symmetry of an action, there exists a conserved quantity, e.g. energy conservation for time invariance, charge conservation for $U(1)$. Is there any similar statement for discrete symmetries?
Comment: @muad: Yes, of a Lagrangian. T symmetry is indeed one of the discrete symmetries I was thinking about. Also, I'd be interested if [CPT symmetry](http://en.wikipedia.org/wiki/CPT_symmetry) implies anything like a conservation law. But also, crystal symmetries might be interesting.
Comment: I am curious if there is a conservation law associated with symmetries of the form psi(x)=psi(x+2*Pi*R) ( a 4-sphere) or psi(x,y)=psi(x+k,y-q) (klein bottle?)
Comment: some interesting reading about this: http://www.technologyreview.com/blog/arxiv/26580/?ref=rss and at arXiv: http://arxiv.org/abs/1103.4785
Answer: For continuous global symmetries, Noether theorem gives you a locally conserved charge density (and an associated current), whose integral over all of space is conserved (i.e. time independent).
For global discrete symmetries, you have to distinguish between the cases where the conserved charge is continuous or discrete. For infinite symmetries like lattice translations the conserved quantity is continuous, albeit a periodic one. So  in such case momentum is conserved modulo vectors in the reciprocal lattice. The conservation is local just as in the case of continuous symmetries.
In the case of finite group of symmetries the conserved quantity is itself discrete. You then don't have local conservation laws because the conserved quantity cannot vary continuously in space. Nevertheless, for such symmetries you still have a conserved charge which gives constraints (selection rules) on allowed processes. For example, for parity invariant theories you can give each state of a particle a "parity charge" which is simply a sign, and the total charge has to be conserved for any process, otherwise the amplitude for it is zero.
Comment: can you provide references on this?
Comment: Isn't this called Pontryagin duality or something?
Comment: @KeenanPepper: [Pontryagin duality](http://en.wikipedia.org/wiki/Pontryagin_duality)? I only looked briefly, but it seems to be about generalized Fourier transforms
Comment: I mean, symmetry in space -- position -- generates conserved momentum, which is the Fourier transform of position. So the idea isn't all that surprising to me. (Very very belated replies but the question has me interested enough to go dig deeper)
Comment: Okay, yeah. If you imagine that the equations of motion (or some quantity of interest or whatever) are functions of say, position, then whatever happens when you 'move the system' (spatially translate, convolve by $\delta(x-x_0)$), the same thing has to happen when you multiply the Fourier transform by $e^{i x_0 \omega}$. If the system is *invariant* under a spatial translation, then the Fourier transform has to be invariant under that multiplication -- and there's not a lot in the kernel of multiplication, it's basically got to be zero almost everywhere.
Comment: i.e. it's some sum of Dirac deltas, so it's got support only at certain fixed quantities in the transform/dual space. Which is, if you tilt your head and squint, basically a conservation law, I think...?
Answer: Put into one sentence, Noether's first Theorem states that a continuous, global, off-shell symmetry of an action $S$ implies a local on-shell conservation law. By the words on-shell and off-shell are meant whether Euler-Lagrange equations of motion are satisfied or not.
Now the question asks if continuous can be replace by discrete?
It should immediately be stressed that Noether Theorem is a machine that for each input in form of an appropriate symmetry produces an output in form of a conservation law. To claim that a Noether Theorem is behind, it is not enough to just list a couple of pairs (symmetry, conservation law).
Now, where could a discrete version of Noether's Theorem live? A good bet is in a discrete lattice world, if one uses finite differences instead of differentiation. Let us investigate the situation.
Our intuitive idea is that finite symmetries, e.g., time reversal symmetry, etc, can not be used in a Noether Theorem in a lattice world because they don't work in a continuous world. Instead we pin our hopes to that discrete infinite symmetries that become continuous symmetries when the lattice spacings go to zero, can be used.
Imagine for simplicity a 1D point particle that can only be at discrete positions $q_t\in\mathbb{Z}a$ on a 1D lattice $\mathbb{Z}a$  with lattice spacing $a$, and that time $t\in\mathbb{Z}$ is discrete as well. (This was, e.g., studied in J.C. Baez and J.M. Gilliam, Lett. Math. Phys. 31 (1994) 205; hat tip: Edward.) The velocity is the finite difference
$$v_{t+\frac{1}{2}}:=q_{t+1}-q_t\in\mathbb{Z}a,$$
and is discrete as well. The action $S$ is
$$S[q]=\sum_t L_t$$
with Lagrangian $L_t$ on the form
$$L_t=L_t(q_t,v_{t+\frac{1}{2}}).$$
Define momentum $p_{t+\frac{1}{2}}$ as
$$ p_{t+\frac{1}{2}} := \frac{\partial L_t}{\partial v_{t+\frac{1}{2}}}. $$
Naively, the action $S$ should be extremized wrt. neighboring virtual discrete paths $q:\mathbb{Z} \to\mathbb{Z}a$ to find the equation of motion. However, it does not seem feasible to extract a discrete Euler-Lagrange equation in this way, basically because it is not enough to Taylor expand to the first order in the variation $\Delta q$ when the variation $\Delta q\in\mathbb{Z}a$ is not infinitesimal. At this point, we throw our hands in the air, and declare that the virtual path $q+\Delta q$ (as opposed to the stationary path $q$) does not have to lie in the lattice, but that it is free to take continuous values in $\mathbb{R}$. We can now perform an infinitesimal variation without worrying about higher order contributions,
$$0 =\delta S := S[q+\delta q] - S[q]
= \sum_t \left[\frac{\partial L_t}{\partial q_t} \delta q_t + p_{t+\frac{1}{2}}\delta v_{t+\frac{1}{2}} \right] $$
$$ =\sum_t \left[\frac{\partial L_t}{\partial q_t} \delta q_{t} + p_{t+\frac{1}{2}}(\delta q_{t+1}- \delta q_t)\right] $$
$$=\sum_t \left[\frac{\partial L_t}{\partial q_t} - p_{t+\frac{1}{2}} + p_{t-\frac{1}{2}}\right]\delta q_t + \sum_t \left[p_{t+\frac{1}{2}}\delta q_{t+1}-p_{t-\frac{1}{2}}\delta q_t \right].$$
Note that the last sum is telescopic. This implies (with suitable boundary conditions) the discrete Euler-Lagrange equation
$$\frac{\partial L_t}{\partial q_t} = p_{t+\frac{1}{2}}-p_{t-\frac{1}{2}}.$$
This is the evolution equation. At this point it is not clear whether a solution for $q:\mathbb{Z}\to\mathbb{R}$ will remain on the lattice $\mathbb{Z}a$ if we specify two initial values on the lattice. We shall from now on restrict our considerations to such systems for consistency.
As an example, one may imagine that $q_t$ is a cyclic variable, i.e., that $L_t$ does not depend on $q_t$. We therefore have a discrete global translation symmetry $\Delta q_t=a$. The Noether current is the momentum $p_{t+\frac{1}{2}}$, and the Noether conservation law is that momentum $p_{t+\frac{1}{2}}$ is conserved. This is certainly a nice observation. But this does not necessarily mean that a Noether Theorem is behind.
Imagine that the enemy has given us a global vertical symmetry $\Delta q_t = Y(q_t)\in\mathbb{Z}a$, where $Y$ is an arbitrary function. (The words vertical and horizontal refer to translation in the $q$ direction and the $t$ direction, respectively. We will for simplicity not discuss symmetries with horizontal components.) The obvious candidate for the bare Noether current is
$$j_t = p_{t-\frac{1}{2}}Y(q_t).$$
But it is unlikely that we would be able to prove that $j_t$ is conserved merely from the symmetry $0=S[q+\Delta q] - S[q]$, which would now unavoidably involve higher order contributions. So while we stop short of declaring a no-go theorem, it certainly does not look promising.
Perhaps, we would be more successful if we only discretize time, and leave the coordinate space continuous? I might return with an update about this in the future.
An example from the continuous world that may be good to keep in mind: Consider a simple gravity pendulum with Lagrangian
$$L(\varphi,\dot{\varphi}) = \frac{m}{2}\ell^2 \dot{\varphi}^2 + mg\ell\cos(\varphi).$$
It has a global discrete periodic symmetry $\varphi\to\varphi+2\pi$, but the (angular) momentum $p_{\varphi}:=\frac{\partial L}{\partial\dot{\varphi}}= m\ell^2\dot{\varphi}$ is not conserved if $g\neq 0$.
Comment: This paper may be useful for the discrete action ideas you suggest: http://arxiv.org/abs/nlin.CG/0611058 *A "No-Go" Theorem for the Existence of an Action Principle for Discrete Invertible Dynamical Systems.*  I haven't read through it yet, but it sounds interesting.
Comment: On my to-read-when-I-get-the-time-list: 1. Hydon & Mansfield http://arxiv.org/abs/1103.3267. 2. Bartosiewicz & Torres http://arxiv.org/abs/0709.0400 3. Torres http://arxiv.org/abs/1106.3597. It seems the papers roughly speaking consider discrete horizontal directions, while keeping the vertical directions continuous; and differentiation in horizontal directions are replaced by differences. Horizontal symmetry transformation are made continuous, which seems to ruin the discrete ideology.
Comment: If you solve the simple gravity pendulum problem, you can construct two independent conserved quantities. They can be combined in a quantity known as the total energy in this case.
Comment: Comment to the answer (v7): Since we consider point mechanics (as opposed to field theory) we may replace Noether current $j_t$ with Noether charge $Q_t$.
Comment: Comment to the answer (v7): What seems to be true is that for discrete horizontal space and a continuous vertical space and if we only consider continuous vertical symmetry transformation $q_t=\varepsilon Y_t$, then we have a version of Noether's theorem: The full Noether charge $Q_t= p_{t-\frac{1}{2}}Y(q_t)-f^0_t$ is conserved in time on-shell. This relies on the fact that it is possible to prove a version of the algebraic Poincare lemma for [finite differences](http://en.wikipedia.org/wiki/Finite_difference).
Answer: You mentioned crystal symmetries. Crystals have a discrete translation invariance: It is not invariant under an infinitesimal translation, but invariant under translation by a lattice vector. The result of this is conservation of momentum up to a reciprocal lattice vector.
There is an additional result: Suppose the Hamiltonian itself is time independent, and suppose the symmetry is related to an operator $\hat S$. An example would be the parity operator $\hat P|x\rangle = |-x\rangle$. If this operator is a symmetry, then $[H,P] = 0$. But since the commutator of an operator with the Hamiltonian also gives you the derivative, you have
$\dot P = 0$.
Answer: Actually there are analogies or generalisations of results which reduce to Noether's theorems under usual cases and which do hold for discrete (and not necesarily discretised) symmetries (including CPT-like symmetries)
For example see:  Anthony C L Ashton (2008) Conservation Laws and Non-Lie Symmetries
for Linear PDEs, Journal of Nonlinear Mathematical Physics, 15:3, 316-332, DOI:
10.2991/
jnmp.2008.15.3.5

Abstract
  We introduce a method to construct conservation laws for a large class
  of linear partial differential equations. In contrast to the classical
  result of Noether, the conserved currents are generated by any
  symmetry of the operator, including those of the non-Lie type. An
  explicit example is made of the Dirac equation were we use our
  construction to find a class of conservation laws associated with a 64
  dimensional Lie algebra of discrete symmetries that includes CPT.

The way followed is a succesive relaxation of the conditions of Noether's theorem on continuous (Lie) symmetries, which generalise the result in other cases.
For example (from above), emphasis, additions mine:

The connection between symmetry and conservation laws has been
  inherent in all of mathematical physics since Emmy Noether published,
  in 1918, her hugely influential work linking the two. ..[M]any have
  put forward approaches to study conservation laws, through a variety
  of different means. In each case, a conservation law is defined as
  follows.
Definition 1. Let $\Delta[u] = 0$ be a system of equations depending on the independent variables $x = (x_1, \dots , x_n)$, the
  dependent variables $u = (u_1, \dots , u_m)$ and derivatives thereof.
  Then a conservation law for $\Delta$ is defined by some $P = P[u]$ such that:
  $${\operatorname{Div} P \; \Big|}_{\Delta=0} = 0 \tag{1.1}$$
where $[u]$ denotes the coordinates on the $N$-th jet of $u$, with $N$
  arbitrary.
Noether's [original] theorem is applicable in the [special] case where $\Delta[u] = 0$
  arises as the Euler-Lagrange equation to an associated variational
  problem. It is well known that a PDE has a variational formulation if
  and only if it has self-adjoint Frechet derivative. That is to say: if
  the system of equations $\Delta[u] = 0$ is such that $D_{\Delta} = {D_{\Delta}}^*$ then
  the following result is applicable.
Theorem (Noether). For a non-degenerate variational problem with $L[u] = \int_{\Omega} \mathfrak{L} dx$, the correspondence between nontrivial equivalence
  classes of variational symmetries of $L[u]$ and nontrivial equivalence
  classes of conservation laws is one-to-one.
[..]Given that [the general set of symmetries] is far larger than those
  considered in the classical work of Noether, there is potentially an
  even stronger correspondence between symmetry and conservation laws
  for PDEs[..]
Definition 2. We say the operator $\Gamma$ is a symmetry of the linear PDE $\Delta[u]  \equiv L[u] = 0$ if there exists an operator
  $\alpha_{\Gamma}$ such that: $$[L, \Gamma] = \alpha_{\Gamma} L$$ where
  $[\cdot, \cdot]$ denotes the commutator by composition of operators so
  $L \Gamma = L \circ \Gamma$. We denote the set of all such symmetries
  by $sym(\Delta)$.
Corollary 1. If $L$ is self-adjoint or skew-adjoint, then each
  $\Gamma \in sym(L)$ generates a conservation law.

Specificaly, for the Dirac Equation and CPT symmetry the following conservation  law is derived (ibid.):
Comment: Comment to the answer (v1): Note that the article is talking about symmetries of equations of motion rather than of the action.
Comment: +1. Very interesting paper and informative answer.
Comment: @Qmechanic, correct the point is that when the conditions of Noether's thrm are satisfied it reduces to the same results for continuous (Lie) symmetries of the action functional (Lagrange functional). In this sense it is a generalisation with the usual N. thm as special case (sth pointed out in the referenced article). Intuitively it is easy to understand why a symmetry induces sth invariant (a "conservation") even a discrete one, these "generalised theorems" state that
Answer: Sobering thoughts:
Conservation laws are not related to any symmetry, to tell the truth. For a mechanical system with N degrees of freedom there always are N conserved quantities. They are complicated combinations of the dynamical variables. Their existence is provided with existence of the problem solutions.
When there is a symmetry, the conserved quantities get just a simpler look.
EDIT: I do not know how they teach you but the conservation laws are not related to Noether theorem. The latter just shows how to construct some of conserved quantities from the problem Lagrangian and the problem solutions. Any combination of conserved quantities is also a conserved quantity. So what Noether gives is not unique at all.
Comment: General comment: there must be something missing in the current generation's education. The past three  yeasr I have been following scientific blogs, I find that most difficulties and misunderstandings arise because people cannot understand or see the difference between necessary and sufficient conditions. How is mathematics taught at present bemuses me.
Comment: @kakaz how is Vladimir's comment different from the paragraph "methods of identifying constants of motion" in wikipedia? http://en.wikipedia.org/wiki/Constant_of_motion  ? Look at the fourth dot. In Goldstein classical mechanics , second edition,page 594, in the discussion of Noether's theorem, there is the clear statement that fulfilling the theorem is sufficient for a conserved quantity, but it is not necessary.
Comment: @anna_v - I am the old fashioned guy - and I have obtained old fashioned education;-) I suppose there is fundamental misunderstanding what kind of systems are disputed here (Hamiltonian or Lagrangian mechanics vs general mechanics etc.). In the former integral of motion means that trajectories lays on certain hypersurfaces which forms differential manifolds - and then Hamiltonian flow defines sufficient structure for  forming Noether theorem (such mechanism is called foliation, please take a look here: http://en.wikipedia.org/wiki/Integrable_system#The_Hamilton.E2.80.93Jacobi_approach ).
Comment: Cont. Then we have theory that for Hamiltonian systems if N integrals of motion exists - system is "integrable" So Vladimir  statement in a case of Hamiltonian dynamics is wrong.  Of course that there exists constants of motion not related to symmetry. But they are not related to *structure of phase space* and there is no *foliation* so in certain meaning they are particular, accidental one. And the may be represented ( after mathematical transformation) as initial conditions of well defined system.
Comment: I would like to add that Goldstein whom I referenced above, in the chapter on Noether's theorem, discusses the conservation laws outside the theorem, and connects them with soliton solutions. He also derives a form for  discrete systems , where only time remains a parameter.
Comment: I think you read to much in my question - I did not assume that the inversion of Noether's theorem, i.e. "For every conserved quantity there exists a continuous symmetry", was true (though I wonder [If _all_ conserved quantities of a system are known, can they be explained by symmetries?](http://physics.stackexchange.com/q/8626/97))
Comment: @Tobias Kienzler I was commenting on the specific answer by Vladimir, and the discussion to this. It is tangent to your question, which was between discrete and continuous systems. I think you got good answers to that, and I learned something from them.
Comment: Vladimir -  but this N conserved quantities are just initial values of trajectory of motion ( chosen one, from infinite possibilities) so they are trivial, and completely different for different trajectories. Symmetry transform this trajectories among others, so there are *interesting* constants of motion, not only trivial ones.
Comment: Wrong, they are non trivial combinations of dynamical variables expressed via initial data.
Answer: No, because discrete symmetries have no infinitesimal form which would give rise to the (characteristic of) conservation law. See also this article for a more detailed discussion.
Comment: Who says that conservation laws can arise *onyly* from infinitesimal forms?
Comment: Unfortunately I can't access that article. But your answer sounds plausible. I still wonder if discrete symmetries offer some other advantage (compared to not having any symmetry at all) besides [Bloch waves](http://en.wikipedia.org/wiki/Bloch_wave).
Comment: @Lagerbaer But proof of Noether's theorem is based on having an infinitesimal version of the symmetry transformation which does always exist for a continuous symmetries.
Answer: As was said before, this depends on what kind of 'discrete' symmetry you have: if you have a bona fide discrete symmetry, as e.g. $\mathbb{Z}_n$, then the answer is in the negative in the context of Nöther's theorem(s) — even though there are conclusions that you can draw, as Moshe R. explained.
However, if you're talking about a discretized symmetry, i.e. a continuous symmetry (global or local) that has been somehow discretized, then you do have an analogue to Nöther's theorem(s) à la Regge calculus. A good talk introducing some of these concepts is Discrete Differential Forms, Gauge Theory, and Regge Calculus (PDF): the bottom line is that you have to find a Finite Difference Scheme that preserves your differential (and/or gauge) structure.
There's a big literature on Finite Difference Schemes for Differential Equations (ordinary and partial).
Comment: The link given is dead. This comment is just to point out that it can be seen on archive.org (https://web.archive.org/web/20100612180152/http://ccom.ucsd.edu/~astern/pdfs/cambridge20081121.pdf). I can't find a copy anywhere else, including on Ari Stern's new page, https://www.math.wustl.edu/~astern/.
Answer: Maybe,
http://www.technologyreview.com/blog/arxiv/26580/
I am by no means an expert, but I read this a few weeks ago. In that paper they consider a 2d lattice and construct an energy analogue. They show it behaves as energy should, and then conclude that for this energy to be conserved space-time would need to be invariant.
Comment: The link is broke. Could you please relink it and write out the title of the article?
Comment: I'm not sure if this is the paper discussed in that article, but it addresses the question posed here: A Noether Theorem for discrete Covariant Mechanics, https://arxiv.org/abs/1902.08997
Answer: See:

John David Logan, "First Integrals in the Discrete Variational Calculus," Æquationes Mathematicæ 9, no. 2 (June 1, 1973): 210–20. DOI: 10.1007/BF01832628.The intent of this paper is to show that first integrals of the discrete Euler equation can be determined explicitly by investigating the invariance properties of the discrete Lagrangian. The result obtained is a discrete analog of the classical theorem of E. Noether in the Calculus of Variations.
Answer: If we can embed some discrete symmetry such as $\mathbb{Z}/N$ via embedding to a continuous symmetry $U(1)$, then we can first derive the Noether theorem for the continuous symmetry $U(1)$. Next we can find the discretized conserved version of Noether current which should be conserved with values mod $N$.
It will be interesting to know whether this thought applies to discrete non-abelian symmetry by embedding to a non-abelian continuous symmetry group, and do the same procedure again.
Answer: Electric charge conservation is a "discrete" symmetry.  Quarks and anti-quarks have discrete fractional electric charges (±1/3, ±2/3) electrons, positrons and protons have integer charges.
Comment: Comments to the answer (v1): (i) The action is not invariant under a discrete change of electric charge $Q\to Q+1$. Thus the transformation $Q\to Q+1$ is not a symmetry. (ii) Noether's theorem shows that global gauge symmetry (which is a continuous symmetry) imply that electric charge $Q$ is conserved. (iii) The fact that electric charge $Q$ only takes discrete values is tied to the predicted existence of magnetic monopoles.
Comment: I'm afraid you're mixing up symmetry and conserved quantity here
Comment: As indicated in one of the answers above, Emmy Noether is the source of the wonderful mathematics that became symmetry, and it all began with conservation of energy and moment, but it got much better, of course.  CP symmetry is conservation of charge and parity.
Comment: The fractional charges of quarks are one of the few places that QCD is quite specific.  It doesn't matter whether the quantization is an elementary charge, or a fractional charge, except in the case of the electron, which, if there were any, would presumably be the entity that gives rise to both magnetic dipoles and monopoles.  As far as I'm aware, Maxwell's equations still forbid those types of monopoles, even if Dirac saw a potential loophole.
Comment: @user41670 How do Maxwell's equations 'forbid' monopoles? They are what they are in accordance with experiment. If monopoles were found the equations would be changed.


Why the photos captured from my mobile camera doesn't give a same results in same conditions?

Question: Last night I was trying to create a time-lapse of the Orion constellation. Setting all the camera settings to manual (max ISO my mobile camera allows 1600 , shutter speed 1 sec), I was trying to capture the images of Orion constellation. For testing the image quality I first set the interval to be 1 second and captured 10 images from the camera. But something which I didn't understand was why the images differ much even when the physical conditions were same. I could capture the two bright stars of the Orion in only first image and later I couldn't. Is this because of change in some physical properties of the camera (sensors and the components) after taking images before ? What's the reason ?
Comment: Can you show a couple of fotos?
Comment: I deleted them after getting above mentioned results. But will add into question taking couple of new photos with same settings.
Comment: You should first check if all automatics are turned off in your camera.
Answer: Stars are point sources of light. This makes it especially difficult for a Bayer masked sensor to generate consistent results as the sky moves slightly between each exposure. The raw data obtained on a Bayer masked sensor must be interpolated by comparing and averaging the amount of light striking adjacent pixels as well as nearby pixels sensitive to the same color. But when a point source of light, such as that from a distant star, strikes the sensor it may fall on only one or two pixel wells. The demosaicing algorithms used by many camera makers will often see these extremely small and isolated light sources as shot noise and remove them in an attempt to denoise the image.
Comment: Okay, is it the only possible reason or can be any other too ?
Answer:
I could capture the two bright stars of the Orion in only first image and later I couldn't. Is this because of change in some physical properties of the camera (sensors and the components) after taking images before?

One reason may be the normal twinkling of the stars. When you look at the stars, you're obviously looking up through an atmosphere made up of many layers of air that are constantly changing slightly in density. Changes in density affect the way the air refracts light, so that at one moment light from a given star hits your eye (or your camera) directly, and the next moment the light from that same star bends away enough that the star disappears or just gets dimmer.
You can reduce the problem by taking a long exposure, or by taking multiple shorter exposures and using software to stack them up and create a single image.


Is there a quick way to copy the Object Name to the Mesh Data Name?

Question: I like to keep my scenes clean. Much of my Blender life is spent naming an object, copying the name and pasting the same object name into the mesh data name. Is there a quick way of doing this (or an add-on out there) where I can name a single-user mesh and the mesh data will be replaced with the same name?
Comment: There's [addon](http://blenderartists.org/forum/showthread.php?386410-Add-on-Replace-object-name-with-mesh-name-on-all-selected-objects) which probaly does something similar.
Comment: I already have Name Panel by Proxe, which should do the same thing, but without documentation, I just haven't take the time to figure out how to do that yet.
Comment: As I tried it you select objects, Space > Mesh To Object name (unfortunately script doesn't have explanation where to find it in UI but I think Space menu was intended). The downside is that you should remember which command to type.
Answer: My answer is a tip rather than a true solution, but it may save your time a bit. Instead of copying and pasting you may just click on the object's icon and drag it to the mesh datablock window.
Comment: That is slightly faster than hover Ctrl+V then hover Ctrl+P, thanks...I will use that as my new workflow if it is the best answer that comes up. I had no idea you could do that.
Comment: Wow that is fantastic, I've been using blender for a few years and never knew about that one, great tip!
Answer: Well I've had the same problem for quite a while, I like keeping my scenes clean and objects well named and always spend considerable amount of time doing so.
There are quite a few addons around that make the task easier though.

Name Panel addon is my favorite and combines a name panel on the properties shelf of the 3D view with a fantastic batch renaming tool for renaming and name copying en mass
There is also Batch Rename Datablocks which also works quite well albeit a little simpler.
And also Batch Naming which doesn't copy names but also does batch renaming
Answer: This script renames all data instances with one user object to the object's name. Just paste it into the Python console in Blender.
objects = bpy.data.objects
for obj in objects:
  if obj.data and obj.data.users == 1:
    obj.data.name = obj.name

Comment: For the simplest of cases this will work fine, for others May or may not work as expected. As mentioned in question needs to be a single user mesh.  If any mesh is shared only one mesh will end up with name of object using it, but will be renamed for each.  If an empty is selected it will throw an error.  Need to narrow down selection accordingly.
Comment: Would go for `if obj.data and obj.data.users == 1:`  since same applies for curves, armatures etc.
Comment: I overread the single-user part. I updated the script to only affect meshes that have a single object.
Answer: I find solution under this post
First, select the objects whose Object Name you would like to copy to the Mesh Data Name. Then use the code below:
import bpy
for obj in bpy.context.selected_objects:
  if obj.type == 'MESH':
    obj.data.name = obj.name

Answer: Another good alternative is Simple Renaming Addon
its pretty good, also has a lot of other renaming options
Answer: And if you want to change the name through Blender's Python API you can run the following:
bpy.ops.object.select_all(action='DESELECT') # Deselect everything in the scene
bpy.context.scene.objects['oldMeshName'] # Select the mesh whose name is going to change
bpy.context.scene.objects.active.name = 'newMeshName'
bpy.context.scene.objects.active.data.name = 'newMeshName'

Comment: One liner: `bpy.context.active_object.data.name = bpy.context.active_object.name`
Answer: a few days ago I had the same issue and came across this post. Realizing that I can't always waste time on manually changing the names of 40+ meshes I decided to make a FREE add-on that adresses the issue.
This add-on allows you to quickly add the _low or _high suffix's to objects name's and datablocks or just copy the object's name to its datablock. All in just 3 buttons!
https://gemesil.gumroad.com/l/Easy-Rename-Blender-Addon
Currently I only tested it on versions 2.8 - 3.0 of Blender but it should work just fine on Blender 3.1 as well.
Hope this saves some of you a bit of trouble :D
Comment: Maybe it was free before but isnt now.


PuTTY - Error: "Software caused connection abort"

Question: I have a problem with my Raspberry Pi 3. When I want to connect to my Raspi, after a few attempts it works, but after while (like 1 minute) it says this error: "Software caused connection abort". I have already added IPQoS cs0 cs0
in SSH config but it didn't work. Any idea how to fix it, please?
Comment: You may also want to read this http://superuser.com/questions/294824/putty-network-error-software-caused-connection-abort
Answer: Try This
I added this to the end of my <code>/etc/ssh/sshd_config</code> file on my raspberry pi, and it seems to have helped keep my connections stable.  I don't remember exactly what it does, but it may help you.
<code># Added to keep sessions up
# Disabled TCPKeepAlive because it was frustrating
# Send an alive message 30 times before judging the connection inactive and closing it
ClientAliveCountMax 30
# Send the alive messages every 30 seconds
ClientAliveInterval 30
# This should total to 30x30 seconds = 15 minutes before inactive sessions are closed
</code>
Comment: Thanks for the advice but it didn't work. :(


Convex Hull on a Spherical Surface

Question: Is there any convex hull algorithm that can be extended to non-euclidean metric, such as the geodesic distance on the surface of a sphere?
Answer: I'm not sure what metrics have to do with it: convexity is about barycentric coordinates rather than distance.
The surface of the sphere is nasty because of antipodes. Roughly speaking, if there is an open hemisphere which contains all of the input points, you can work in that hemisphere without problems. Otherwise, the convex hull is going to be the entire surface.
Supposing that there is an open hemisphere containing the points, essentially any 3D convex hull algorithm will work by the addition of an extra point at infinity. But it's probably more elegant to take the centroid in $\mathbb{R}^3$, project to the surface, and use it as a centre around which to apply your favourite wrapping algorithm.
Comment: Can you explain why the convex hull is the entire surface if the points don't lie in a hemisphere?

Convex Hull on a Spherical Surface


What are the buoyancy control mechanisms of Chambered nautilus?

Question: I'm currently working on an underwater robot and was hoping to use the principle used by the nautilus for buoyancy control. So how do the Chambered nautilus control its buoyancy?
Comment: Voting to reopen, since there are no comments explaining why it is unclear. It is lacking in background research but, to me, it is pretty clear what the Q is asking for.
Comment: They achieve buoyancy in a similar way to submarines: by drawing water in (via hyponomes) to sink, and expelling it to rise. The expulsion is also how they achieve propulsion.
Answer: The various species of nautilus use a combination of active transport of salts and passive diffusion of water for buoyancy (Denton and Gilpin-Brown 1966, Ward 1979, Greenwald et al. 1980). The chambers are filled with seawater. Salts from the seawater in the chambers is removed by a structure called the siphuncular epithelium. This process makes the chambered water hypotonic, meaning it has lower solute concentration relative to the animal. The hypotonic water then diffuses from the chambers into the blood, creating air pockets in the chambers. Greenwald and Ward (2010) have a recent summary of what is known about nautilus buoyancy, if you want to know more.
The diffusion of water in  is not a rapid process. The maximum ascent and descent rate of Nautilus from depths appears to be about 3.0 m m$^1$ (Dunstan et al. 2011).  This does not seem like an efficient process or rate of depth change for an underwater robot.
Literature Cited
Denton, E.J. and J.B. Gilpin-Brown. 1966. On the buoyancy of the peraly nautilus. Journal of the Marine Biological Association of the United Kingdown 3: 726-759.
Dunstan, A.J., et al. 2011. Vertical distribution and migration patterns of Nautilus pompilius. PLoS ONE 6: e16311. doi:10.1371/journal.pone.0016311
Greenwald, L., et al. 1980. Cameral liquid transport and buoyancy control in the chambered nautilus (Nautilus macromphalus). Nature 286 55-56.
Greenwald, L. and P.D. Ward. 2010. Buoyancy in NAutilus. Topics in Geobiology 6: 547-560.
Ward, P.D. 1979. Cameral liquid in Nautilus and ammontites. Paleobiology 5: 40-49.
Comment: How does the diffusion hypotonic water  from the chambers into the blood, creating air pockets in the chambers?? Wouldn't that lead to vacuum creation ??
Comment: I do not know but I would guess that it might be similar to the swim bladder in fishes. The gases are extracted from the blood stream and diffuse into the chamber. In fishes this happens by countercurrent exchange.
Answer: As the siphuncle pumps cameral liquid out of a chamber, the pressure of the chamber falls and nitrogen, oxygen, and some carbon dioxide diffuse into the chamber.  Sea water gas pressures are in equilibrium with atmospheric gases (oxygen and nitrogen) and are in equilibrium with nautilus blood.  Hence as cameral liquid is pumped out of the chamber, gases enter from the blood.  But it would make no difference to the buoyant state of the animal if gases entered or if there were a vacuum.  The emptying mechanism relies on sodium pumps transporting salt out of the cameral liquid.  There is no way to duplicate this biological mechanism in a mechanical system.


Why do we not include water in equilibrium expression calculations?

Question: Why do we not include water in equilibrium expression calculations? And can you go into detail on why pure liquids and solids have a constant concentration as well, please and Thanks.
Comment: Related: http://chemistry.stackexchange.com/questions/42008/why-is-water-not-part-of-the-equilibrium-constant
Answer: Usually when you have water in a reaction it is taken in excess, i.e in a much larger quantity compared to the other reactants. Ultimately the change in concentration of water is negligible. As an example you can consider the hydrolysis of ethyl acetate to ethanol and ethanoic acid. For better understanding consider the initial amount of ethyl acetate to be 0.01mol and that of water as 10 mol.
This however is valid only when water is taken in excess. If the amount of water and the other reactants is comparable, then water has to be included in the equilibrium expression.