How would you discover hosts on a network if they have stateful firewalls set up?

Question: I've been wondering how it would be possible to accurately map a network using something like nmap and discover hosts on the network if those hosts have stateful firewalls set up that filter packets based on the source IP address, port, and sequence number of incoming packets.  The source port and IP address you can obtain by monitoring the network with a packet sniffer like Wireshark or TCPdump, but the sequence number is something that constantly changes, and you would have to get it right and with precise timing, meaning you would have to send a discovery packet with a sequence number that is exactly one greater than the sequence number of the last packet that the host received.  Of course you can bruteforce the sequence number (not sure how to do this with nmap), but you also want to do it transparently, and there's the fact that if your discovery packet does successfully reach the host, its firewall will filter out further traffic they were meant to receive, resulting in an error on their end and making your presence at least somewhat visible.  Is there a way to avoid this problem?  Have nmap and other network scanners accounted for stateful firewalls in recent years?
Answer: If you've got access to devices like routers and switches, or a host on the same subnet as the mystery device you can easily identify it regardless of whether it has a firewall or not.
Using the above mentioned devices you could monitor the VLAN's traffic and therefore identify all of the hosts on it without having to probe any of them with tools like nmap. The reason being that the mystery host would eventually send data and would therefore reveal its MAC & IP address in the process so you now know it exists even though it didn't respond to your earlier probes.
Further to this, during your monitoring you would be able to keep tabs on what the mystery user is doing by viewing the contents of their network traffic (provided that it's not encrypted). This could then assist you in identifying who the user is. For example, if they use telnet you could get their username (and password, though passwords are best left alone). If the traffic was encrypted, you would still be able to view the destination IP address(es) of the sites they're visiting which you could then look up.
Finally, you could also see what protocols they're using by viewing the captured traffic as well (provided that the software you're using to view the capture e.g Wireshark, has a decoder for the protocol(s) used). This shouldn't be a problem unless the mystery user has custom written the protocol.
Answer: One of the benefits of firewalls is that they can render hosts, or whole networks, invisible. The idea behind this is that the owner of the firewall can block or allow whatever traffic is desired. An external tool will not be able to get a host to respond if the host's firewall doesn't allow it. The tool would need to not only find a port in use for a traffic flow, but it would also need to spoof the source IP address and port of the traffic allowed through the port since the firewall opens a port for a specific traffic flow (IP address + port number).
This can render things like port scans useless. Depending on where your sniffer is placed on a network, you may be able to sniff network traffic to discover devices on the network, but this may not be possible, either.
If the network owner does this in order to prevent someone from network discovery, attempting this is trying to bypass network security or policies which is specifically off-topic.
Answer: Although nmap can do some things to 'get around' stateful firewalls, its basic use is in identifying running services.
Yes, I know it is called nmap for a reason, but I do not believe its primary use case is mapping firewall-protected remote networks (rather, you would use it to see what a given range might be exposing - shodan exists in part because what people think is exposed and what is exposed are often different).
If you have a host within the same broadcast domain, then you can enumerate all hosts whether or not they have a firewall, by generating some kind of ARP ping.
One way of doing that would be to try and send a single ICMP echo request to each host, and then check your ARP table for live entries (e.g. using ip n).
If you are not within the same broadcast domain, then it is another matter. You could mess around with GRE and IPIP, I guess (there is a slim chance that could do something for you), but in general, stateful firewalls will do their job fairly effectively, and obfuscate much of the network they are trying to protect.
That said, it never hurts to look at the TTLs of returning packets, in order to try and get a sense of the network's depth.
Answer: You use an arp scan. Since arp packets never hit the IP layer they will never hit the IP firewall.
IIRC nmap will do this by default if the targets are on the same subnet as the scanner.


Are questions about learning new languages on or off topic?

Question: I want to learn Mandarin and have some specific questions on how to start, which resources I should use and so on. The Chinese Language Stack Exchange Site is still in the commitment phase and I am looking for a place to ask my questions instead. Would this be the right place?
Comment: It's now beta. You can ask it there. (I notice that you have not put any questions, so I left this comment)
Answer: In short, as is, that question is not on-topic for here. linguistics.SE is for general characteristics of (multiple) languages, and maybe linguistic questions about particular ones, but certainly not about how to go about learning a particular language.
To be on-topic (for anything) tautologically a question has to be relevant to the site. Suppose you have the general question 'How do I learn Chinese?'. Ostensibly this has nothing to do with linguistics.SE. But depending on how you repackage it, you might be able to get something.
You might ask 'What are general methods for learning languages?' where the answer would be expected to be more theoretical than pedagogical, or 'Are there any tools for language learning that are specific to Asian languages (or Sino-Tibetan, or something else)?'. The idea is to package it more locally. For here it would be 'local' to mention language families, or with a more theoretical bent.
Comment: +1 splitting a general question to a series of scientific/theoretical questions is the way to go
Answer: Usually Q&A sites are not the standard place for that kind of questions.
I think it would be considered off topic, also because you're asking about a specific language, and this site is not about a specific language, but about all languages.
If everyone would ask questions for all languages, it wouldn't be a Linguistics SE anymore. The question is not bad per se, it's just that I don't think it would fit here.
Comment: You are moderator when you indicate an question.


How do I earn the "I am a genius!" Achievement?

Question: I recently bought Surgeon Simulator from the App Store and there are a list of achievements you can earn. I was scrolling through the achievements and I happen to see an achievement where you have to create a hammerhead shark. I am confused, so how do I earn this achievement?
Comment: A true genius wouldn't have to ask would they? ;)
Comment: put the head of a hammer on a shark? lol
Answer: The answer is quite simple actually. Take this achievement in literal terms and strike the patient in the head during an operation. I hope this helps!
Comment: That's how I lost my medical license.
Answer: You need to hit the patient in the head with a hammer to get this achievement . You will actually need to perform this procedure during the eye transplant.
Answer: You can get this by gouging the eye halfway out in Eye surgery then striking the patient on the temple with your hand. I did this with all my fingers contracted. Might've been a glitch but it worked for me.
Comment: Are you certain you have to gouge out the eye? The other answers do not mention this.
Comment: This is just how I got it. I'm not sure if you have to gouge out the eye or not.


Did the Olympic Comittee consider cancelling the 1936 games in protest?

Question: Did the IOC consider cancelling the Olympic Games in Germany at the time in protest of developments in Germany?
Comment: Isn't that incident based on an apocryphal story? https://www.snopes.com/fact-check/jesse-owens-and-hitler-handshake/ "Jesse Owens tells everyone who will listen, look, Adolf Hitler did not snub me. But nobody wanted to hear that story. And the story proved remarkably durable, and persists to this day."
Comment: @DenisdeBernardy: The athlete Hitler refused to shake hands with (leading to the admonishment by the IOC) was [Corny Johnson](https://www.sports-reference.com/olympics/summer/1936/ATH/mens-high-jump.html) (men's high jump, on the first day of the games), not Jesse Owens. From the second day (August 3rd) on, Hitler did not shake hands with any medalists. All of Owen's medals were on August 3rd or later. And IIRC, Hitler had left the stadium before the (late) medal ceremony for the 100m dash (Owen's first medal).
Comment: The best way to answer this question would be by checking whether Hitler (or perhaps other high-ranking German officials) shook hands with non-German Europeans which won various important medals. Also, it's not clear how any single country could win the (entire) Olympic competition, since it contains literally dozens of contests; or why one would think that if one country had some luck in one particular edition, their winning streak would go on [indefinitely](http://en.wikipedia.org/wiki/Gambler's_fallacy).
Comment: Isn't the title and the last para quite different than the Owens part between? Would you mind cutting that out and instead include your own prior research on the main focus of the question?
Comment: Really, no offense intended when deleting circumstantial conjecture from the question body. Aside from the whole handshake thing, "they must've, so why didn't they" is just distracting to the actual question. If they did consider, let the answer elaborate on their reasoning.
Answer: For some perspective:
In 1936, which is five years after the Japanese invasion of Manchuria, the IOC gave the 1940 summer olympics to Tokyo.
While there were talks of boycot, and while the international pressure certainly played a part, it was Japan giving the rights to the 1940 summer olympics back to the IOC in 1938, which is one year after the outbreak of the Second Sino-Japanese War.
What had happened in / with Germany by 1936 was positively tame by comparison. The IOC was not in a habit of cancelling olympic games for political reasons, and certainly wasn't quick about such a decision. The Nazis had been in power for a scant three years, and neither fascism, racism, or militarism were exactly uncommon at the time. What concerns were voiced by the IOC were easily mollified by the Nazi government.
Comment: I am a bit unsure why the main point of the Vienna meeting – which was 'what to do now' including whether to remove the games from Berlin, among others – shouldn't count? We know the end-result of that session and how it played out, namely that they *decided* to let Berlin host. But OP: "did they [consider"?](https://www.jewishvirtuallibrary.org/the-nazi-olympics-august-1936) Seems to me that early on this was seriously an option, and when repeated as threat later it grew ever more hollow?
Comment: @LangLangC: I missed that particular source the first two times I looked at your answer. Was it there all along? I'll have to take a look at it and re-phrase. For now, I'll remove the surrounding wording.
Comment: I don't know when you read it. But you mean the link I just put in comment? It *is not* in my A, you know length… ;) / One point to criticise in your A: I agree with the content, but for me it still reads a bit as if your primary understanding of the Q was "did IOC *in 36* consider cancelling the 36 games"?
Comment: @LangLangC My angle here is not "in '36", but rather "seriously". There is always someone calling for this and that, and there's a lot discussed in committees that gets dismissed rather quickly as it has no real support. I hadn't been aware of any "real" consideration of such a move by the IOC before, just limited public / national protests.
Comment: I see. Although 'seriously' might be a bit wobbly to define, lest you set the bar to 'reached decision and published official statement – after pleas and struggle took it back after a while'. Unfortunately, we might be waiting a rather long time for clarifications of Q now. :(
Answer: Yes, there were "considerations" of such a move, cancelation of the games, relocation of the games, or boycotting the games.
In 1933 the whole IOC session in Vienna was dominated by answering this question. While they considered a range of options, we know they decided against such 'harsh' measures and were content with nazi assurances.
The official publication by the IOC reporting on the Vienna session leaves out most of the controversy it is meant to describe but still retains the American position of threatening non-participation if negotiated guarantees should not be met.
These considerations began immediately after the Germans started implementing fascist policies in 1933 and continued throughout until 1936. Although not by the IOC as institution, threatening 'ideas' of individual and high-level members continued to be an issue, one that was lost.

VIENNA, June 3 -- As delegates to the International Olympic Committee meeting, scheduled for next week, gathered today, there was a distinct movement afoot to cancel the award of the 1936 games to Berlin because of the anti-Semitic movement there.
–– "Proposal To Shift Olympics Growing; Distinct Move Is Afoot Among International Delegates to Cancel Berlin Award.", NYT, The Associated Press. June 4, 1933.
BERLIN, Aug. 6. -- An authoritative source expressed the belief today that fear of losing the 1936 Olympic Games because of the campaign against Jews and "political Catholicism" lay behind Nazi attempts to obstruct foreign correspondents.
–– "Nazis' Dread of Losing Olympics Is Blamed For Efforts to Ban News of Drive on Foes", NYT, The Associated Press, Aug. 7, 1935.

The desires and options were for a time quite looking to be successful, but as we know the leave-it-be faction won.
Why was that the case?
The strongest voices against "Nazi Games" were in France, fuelled by German immigrants who fled Nazsim and disliked the outlook of giving Germany an opportunity for propaganda, and in America voices who wanted mainly either to show that 'the American system' was superior to German fascism, or equal participation opportunities for Jewish and black athletes.
After all, Nazi policy is pretty much against the 'spirit of Olympia', something most often argued in France. And this concern led to the open debate from the German side, which wanted to extend racial policy immediately to the games. They were publishing strongly voiced in the Völkischer Beobachter and even worse outlets, how it should be outright forbidden for Jews and black to even show up on the one hand. The named newspaper also did that in 1932 to discredit the Los Angeles Olympics:

Negroes have no business at the Olympics. Today we witness that free white men have to compete with the unfree Negro. This is a debasement of the Olympic idea beyond comparison. The next Olympics will be held in Berlin in 1936. We hope that the responsible men know what will be their duty. The blacks have to be expelled. We demand it.

When nazi-ideas became official German policy in 1933:

Bruno Malitz published an official brochure of the Nazi Party in which he claimed:

Sports and physical education are creating physical and spiritual values. The Jew is laying his hands at all things which create values, as he is destructive. So he tried to gain control of German sports for its decrement. The Jewish teaching destroys the vigour of the people. The Jewish sports leaders and those infected by the Jew, the pacifists, the Pan-Europeans have no more place in German sports. They are worse than cholera, tuberculosis, and syphilisyas these destroy only some Germans[;] the Jews, however, destroy Germany herself.
    And on the other side of the Olympic committee and other member states a desire to ensure the olympic spirit was held up and that Germany should not only be not allowed to dictate other nation's teams ethnic make-up but even more so that Germany would have to ensure that Jews would be allowed into the German team.

But leading members of the IOC were sympathisers of racism, fascism, even Hitler personally and couldn't care less about esprit.
Notably, French IOC president Henri de Baillet-Latour asw the need to address all this at the 32 session of the IOC  5. – 7. June 1933 and demanded a written guarantee for such provisions from Germany. But while that may sound noble, he also argued the universal fallacy of the possibility of being apolitical:

In June 1939, the IOC voted unanimously in favour of Germany organising the 1940 Winter Games, replacing Japan that had returned the right to organise the 1940 Games. De Baillet-Latour argued that the decision in favour of Nazi Germany, which had occupied the Czech rump state three months before, showed the IOC's independence of political influences.

It is argued that the Vienna meeting would have been the most reasonable chance to change the place, if ever they really cared. Or had a viable alternative at hand. Only that these were Rome in fascist Italy, Tokyo in Japan, Barcelona in troubled and soon equally fascist Spain. And gain a pro-German Lewald led the meeting.
(D. L., Hulme: "The political Olympics: Moscow, Afghanistan, and the 1980 U.S. boycott", Praeger: New York, 1990.)

The IOC arranged a shrewd deal with its German members who were equally worried about the Nazis themselves and attempted to safeguard their own position: the IOC demanded that its members remain in charge of the organisation and that all Olympic rules would be strictly adhered to. When this was achieved, the American IOC-member General, Charles H. Sherrill, a former US Ambassador, demanded additionally that German Jews should not be excluded from the German team. This interference into the internal affairs of another country was unprecedented in IOC history. At a time of racial segregation, when competition between white and non-white athletes could not take place in the American South, when major US sports were still segregated, nobody had demanded that African-American athletes be given a fair chance to qualify for the 1904 or the 1932 Olympics in the United States. However, in this case, it was essential that Lewald secured such a statement on behalf of the German organisers to placate international critics.
In these respects, it seemed, all parties involved were contented; the American press celebrated its victory. The American IOC members were happy as they arrived home as victors in the battle, as they saw it, against Nazism. The German IOC members were pleased as they had defended 'their' Games; and, the Nazis were happy as they could host the Games in Germany. The declaration that had won the day for the Nazi Olympics was not even published by the state-controlled German press.

But the Republican American Charles H. Sherrill was keen to let the Games take place. He is remembered for

Support for dictators
  Shortly after retiring from public office Sherrill proclaimed his admiration for Europe's strong men and predicted the end of parliamentary form of government, which he dubbed "inept" and referred to as "so-called democracy." In a long letter to the editors of The New York Times, published on June 4, 1933, he singled out Benito Mussolini, the fascist dictator of Italy, for praise and spoke of the "amazing betterment" of life accomplished by his régime. He wrote of Adolf Hitler, the new leader of Germany, "Whether one admires [him] or not, at least he is a leader who leads." Soon enough, he wrote, "people the world over... will follow courageous leaders."
1936 Olympics
  In 1935, during the preparations for the 1936 Olympic Games, Sherrill met twice with Hitler. A modern historian wrote that Sherrill was "mesmerized by the force of Hitler's personality and charisma." In his one-hour talk with Hitler, Sherrill insisted for at least one token Jew to be included in the German team for the Olympic Winter and another for the Olympic Summer Games. Hitler refused and when he was threatened by Sherrill with an American boycott, promised purely German Olympic Games. Sherrill sent the information to the IOC president, Henri de Baillet-Latour, who did not insist on Jewish participation on the German teams. After the Nuremberg Racial Laws, only Half-Jews, with no more than two of the four grandparents being racially Jewish, were still permitted to represent Germany. With Theodor Lewald as President of the Organizing Committee for the Summer Games, Rudi Ball (hockey, Winter Games) and Helene Mayer (Fencing, Summer Games), three Half Jews calmed world public opinion.

Equally, Avery Brundage the American president of America's NOC AOC and the AAU was so keen on US participation that he even manipulated a vote he was sure to loose over boycotting the games or not.
It seems that as the games approached the public debate in the US increased and opinions published appeared to roughly equal.

The main focus was on the US, as the American team had always placed first in the Olympics with the exception of 1912, and was considered neutral. In this respect, American opinion and participation mattered. American athletes had participated individually in German sports events during the Nazi years; however, the decision was not to be taken by the athletes but, rather, by the AAU and the AOC. Judge Jeremiah Mahoney, AAU President, was against participation, while Avery Brundage, AOC President, was in favour. […]
  Both sides published pamphlets, staged rallies, gave radio and newspaper interviews, and lobbied political representatives to take sides. Most of the public debate issues were outside the actual field of sports and dealt more with the question of having the most important international gathering, symbolising the search of the world's youth for peace, understanding, and equality, under he Nazi symbol of the Swastika, itself representing an entirely different set of values.
The pro- and anti-boycott sides clashed, nevertheless, in a decisive show-down in New York in December 1935. But it was too late to ask for a transferral of the Games; the only question that remained was whether the American teams would go to Germany or not. The discussion followed along the lines of the aforementioned arguments.
At this time, Avery Brundage used two political tricks, which underlined his skill as a master strategist. Normally, the certification of an athlete for participation in the Olympics required three signatures – that of the athlete, that of the sports federation (here, the AAU), and that of the National Olympic Committee (here, the AOC). Brundage had secretly secured the agreement of Baillet-Latour that, under these extraordinary conditions, the signature of the AAU would not be necessary. Brundage described this to his friend and IOC member, Sigfrid Edström, as the "death knell for the AAU". By virtue of this secret agreement, a vote against participation and certification of the athletes by the AAU would have meant a reduction of its influence.
Brundage's second trick was performed directly at the AAU convention. When he realised that he might still lose the final vote, he sought to stretch out the discussion through the night. By morning, he had secured several more eligible voters by telegram. With their help, he gained a final 58 1/4 vs. 55 3/4 victory. According to voting procedure, the AAU districts each had three votes (54 1/2 vs. 41 1/2 for non-participation), the past and present Presidents two votes (1 3/4 vs. 1/4 for going), and the associated sports bodies, many of which were brought in by Brundage over night – in a display of support never seen before – cast their ballot (one vote each) 15 vs. 1 in support of attending in Berlin. The next day, the AOC voted unanimously for participating in the Berlin Olympics.

Brundage also ensured that the American team was "presentable" – by excluding Jewish athletes (Javier Cáceres, Holger Gertz: "Glickmans Trikot. Die Amerikaner kuschten 1936 vor den Nazis und ließen ihre jüdischen Athleten nicht antreten", in: Süddeutsche Zeitung, 1. August 2015, p3.) Also compare Arnd Krüger:  "'Fair Play for American Athletes' A Study in Anti-Semitism", Canadian Journal of History of Sport and Physical Education, 9(1), 43–57, 1978. doi:10.1123/cjhspe.9.1.43
He was perhaps the loudest voice – after floating the idea of cancelling the games in 1933 himself – dismissing any idea of cancelation as the games approached.
In 1933

Brundage told a newspaper reporter:

My personal, but unofficial, opinion is that the Games will not be held in any country where there will be interference with the fundamental Olympic theory of equality of all races. The Olympic protocol proves there shall be no restriction of competition because of class, colour, or creed.

Otherwise he felt that the Games might be transferred to one of the other bidding cities - Tokyo, Barcelona, Rome perhaps – or they could be cancelled altogether, as they were in 1916, ironically the only other time that Berlin had been scheduled to stage them. And, of course, if they went ahead and were boycotted by enough countries, then Germany would lose out anyway, since that would be a massive propaganda own-goal. In the end, though, said Brundage, he fully expected the issue to be resolved when the IOC convened in Vienna in June. A day after the New York Times headline suggesting that the Berlin Games might be cancelled, the newspaper ran an interview with Lewald's Olympic partner, Carl Diem, who professed shock that the Games might be in jeopardy, adding that there was no discrimination in German sport.
 –– Anton Rippon: "Hitler's Olympics. The Story of the 1936 Nazi Games", Pen & Sword Military: Barnsley, 2006.

Even as late as the Winter-Games in Garmisch-Partenkirchen 1936:

The IOC took a middle path. When Baillet-Latour saw anti-Semitic signage peppering the German landscape he complained vehemently to Hitler, threatening to cancel the Games. The Führer relented, ordering the signs' removal. In Avery Brundage's personal notes, he wrote, "Baillet-Latour said to Hitler 'You keep your law, I keep my Games.'"
Opposition to the Nazis' racist policies emerged in the United States in 1933, when the Amateur Athletic Union voted to boycott the Games unless anti-Jewish discrimination was reversed in Germany. The AAU vote did not influence the group that mattered, the American Olympic Committee, which decided to participate in the Games. The decision was made after the committee chief, Avery Brundage, made a "personal investigation" into the matter and received a pledge from the German government not to discriminate against Jewish athletes. Nevertheless, the push to boycott the Games continued from a variety of sources, including students at Columbia College, various religious groups, and the Committee on Fair Play in Sports, a liberal organization formed specifically to oppose American participation at Berlin. To be sure, the United States had its own deep-seated problems with racism, but the 1936 Olympics provided a chance to point the finger away from home. In a March 1935 Gallup poll, 43 percent of respondents favored a boycott.
Brundage's "personal investigation" largely entailed listening to and then believing German officials. The more Brundage publicly explained his reasoning, the more flimsy it appeared. He told the New York Times: "Germany has nothing whatsoever to do with the management of the games. The Germans provide the facilities and make preliminary arrangements, but that is all." The Olympics, he argued, was "under the sole jurisdiction" of the IOC. Plus, he added: "The fact that no Jews have been named so far to compete for Germany doesn't necessarily mean that they have been discriminated against on that score. In forty years of Olympic history, I doubt if the number of Jewish athletes competing from all nations totaled 1 per cent of all those in the games. In fact I believe one-half of 1 per cent would be a high percentage." Behind the scenes, he was more direct about his feelings. When Edström wrote Brundage to complain that "all the Jews in the whole world are attacking us," Brundage responded with an accusatory screed:

The situation on this side of the Atlantic has become extremely complicated. As you no doubt know, half of the Jewish population of the United States is centered in New York City. The New York newspapers which are largely controlled by Jews, devote a very considerable percentage of their news columns to the situation in Germany. The articles are 99% anti-Nazi. As a matter of fact, this applies to the American press generally. As a result, probably 90% of the populace is anti-Nazi. The Jews have been clever enough to realize the publicity value of sport and are making every effort to involve the American Olympic Committee. Boycotts have been started by the Jews which have aroused the citizens of German extraction to reprisals. Jews with communistic and socialistic antecedents have been particularly active, and the result is that the same sort of class hatred which exists in Germany and which every sane man deplores, is being aroused in the United States.

Brundage's biographer asserts that Brundage "continued obstinately to see a conspiracy of Jews and Communists" and that he was blinded by his anti-Semitism.
–– Jules Boykoff & Dave Zirin: "Power Games: A Political History of the Olympics", Verso Books: London, New York, 2016.

Individual calls for boycott remained strong until the summer 1936, but hopeless and some naive minds hoped that the games would change things for the better in Germany.

Non-marked non-Wikipedia quotes from –– Arnd Krüger: "The Nazi Olympics of 1936", in: Kevin Young & Kevin B. Wamsley (Eds): "Global Olympics. Historical And Sociological Studies Of The Modern Games", Research in the Sociology of Sport, Volume 3, Elsevier: Amsterdam, 2005.
Comment: Hm.... lots of interesting stuff in that answer, but I see no quote / source for *the IOC* considering a *cancellation* of the games (which was the question). I see quotes that they made demands, and I see quotes that the *AOC* considered a boycot (of the *American* team), but nothing about a move to scrap the Berlin games altogether.
Comment: As a kind of general (constructive!) criticism... I applaud your research and thorough quoting style. But I keep noting that your answers tend to be quite long, and often meandering a bit over loosely correlated matters. I feel they would be much more approachable if you focussed them down a bit on the actual issue. Less chance for bringing up controversial side plots, too. (Not in this case, but generally speaking.)
Comment: @DevSolar Thx, for the criticism. Re 'cancel':  the two gBooks links and the start of the last quote? (But note that outright cancelling – even without alternative – I would consider an empty threat in 33 and evenmore so by 36) Then, while waiting or OP to clarify – I read the Q as more inclusive: 'possible measures to be taken by the IOC in response', among them ideas for cancelling by members (not the entire IOC, though)?
Comment: 1st gBook link: "The IOC was satisfied, however, when the German side declared..." I utterly fail to see the relevance of the second link, which doesn't seem to relate to the Berlin games at all other than mentioning that Brundage was a *supporter* of the Nazis... I read Baillet-Latour's protest of the anti-semitic propaganda as a kind of generic "or else!", which is quickly mollified. A real "consideration" to cancel the games (or other measures) should have left some kind of paper trail, either directly from the IOC or the commentary, I feel.
Answer: Why should the IOC cancel the games because someone 85 years later doesn't like Hitler much? And yes, a lot of people don't like him now, but at the time that wasn't the case. He was very popular, including outside Germany. And still that's irrelevant, the Olympics aren't supposed to be about politics.
There were Olympic games much more recently in countries with pretty bad human rights records.
Moscow comes to mind, and Beijing.
And if you don't hold the games because someone doesn't like the country they're to be held in, there won't be any games. North Korea objected to the games in Seoul, the USSR to the games in LA, I'm sure someone didn't like that Japan got to organise the games not once but twice (or was it 3 times by now), the list goes on and on.
Pretty much the only reason to cancel the games is if the country organising them is an active war zone, as that would make it way too dangerous for the athletes and audience to go there (if they could get there at all), and would hint at the IOC taking sides in that war which they wouldn't want to do.
The games are about uniting people, not tearing them apart, a place where athletes from countries that are otherwise at odds can come together and compete in a reasonably friendly atmosphere without too much interference by outside agencies.
And that's exactly what happened in 1936. If the German politicians weren't keen on acknowledging the successes of foreigners, that's no problem, the athletes among themselves did acknowledge them.
Comment: -1 for the sentence "85 years later doesn't like Hitler much".  Very many people disliked Hitler much earlier, and by 1936 the regime murdered many people. However you are right that the "intenrational community" and the Olimpic committee in particular does not care much about such things.
Comment: Yes, that gave me a double-take as well. With the "85 years later" removed, that intro would still be a bit snarky but acceptable. ;-)


Is it possible to find encryption key in Tor Browser?

Question: I'm doing a presentation on Tor. Is it possible to capture and find keys and decrypt data.
Answer: If you're doing something like a presentation, paper, book, etc, it's best to 1. Ask the developers and contributors directly https://www.torproject.org/contact/ and 2. Read the documentation for yourself.
So, you open the Tor browser and connect to your favorite website anonymously. Tor Browser reaches out to a guard node. The guard sends the browser its public keys. The packets are then encrypted with those keys and sends them off to the guard which then then sends them to the next node, etc.
The browser does not ever get to see any private keys and so there are none to be found.
See also these links:

Understanding and Using Tor - An Introduction for the Lay(wo)man
Theft Of Tor Relay Private Keys? (scroll down to find the
section)


How standard are SIM card prices across Israel?

Question: Is the price of a SIM card generally standard across Israel, or are prices variable, such as much higher at the airport?
Answer: Just back from Israel and can now report that a sim card at the airport cost $20 more than on the vendor website: https://019mobile.com/ (i.e., $50 vs $29). A friend said she paid $20 for a similar card from another vendor, but I do not know the details of the plan.
Answer: Prices exhibit a lot of variance.
First, at the airport you get ripped off, for sure. See also the answers on @Yehuda_NYC's other question.
However, even regardless of that - Israeli communications providers are notorious for a combination of discounted sales + price gouging when they can get away for it. So it's very possible you could see a factor of 4 or higher of difference even in the fees that resident Israelis pay, if they're not careful.
Also, in recent years and specifically in 2019 there are spates of renewed competition with new cellular operators (or virtual operators) entering the market, taking prices down. A (resident) with a SIM can now get a decent plan for a monthly rate of ~15 NIS (~4.2 USD) per month for the first year, and ~30 NIS (~8.4 NIS) afterwards. So even the $29 rate of 019 Mobile is very high. Of course, those rates are for people who already have a SIM. Still, for 30 NIS you can get a HOTTalk package by Hot Mobile: 500 min voice, 500 SMS messages, 5 or 10 GB data, not exactly clear; expires in 10 days. This of course requires that you actually visit a HOT Mobile store/booth/service center.
Also, if you order a new SIM to be sent to you, you're often charged a lot - as much as 40 or 50 NIS.


Are there any advantages to applying on a job board vs. the direct company's website?

Question: I am finding jobs through job boards and if the company has a website, applying directly through there. Are there any advantages to doing so as compared with applying from a board such as Dice, Monster, Careerbuilder, etc? Does it look any less/ more professional to bypass the middle man (the job board in this case) and apply directly on their site?
Comment: Related: [Pro's and Con's of sending a resume directly to a potential employer vs. through a recruiting agency](https://workplace.stackexchange.com/questions/59399/pros-and-cons-of-sending-a-resume-directly-to-a-potential-employer-vs-through)
Comment: Has the company posted the job on their website and offered a pathway to apply through their website? If yes, go ahead, as others said - it makes no difference. However, if the only advertised pathway is the third party job board, your application may not get to the right person, and may be ignored if it did.
Answer: Some companies use job boards rather than their own websites, that's the only one I can think of.  Even the ones that use job boards have a link on their website.
Personally, I would go to the company's website regardless, as you can do a little legal corporate espionage to learn about the company, their values, culture and interests (then over to the financial sites to see how stable they are)
As to if it looks more professional...
If I were a hiring manager and knew that you came to our site to look at our company, you'd move to the top of the list because it tells me that you're not looking for "a" job, but that you are interested in my company.  I'd consider that far more professional than digging through the job sites and applying to anything you think you're a good fit for that position.
It tells me that you want to work for my company, which is going to get my interest.
Answer: The reasons companies post their open positions on more than just their own website is that they increase their chances of reaching potential employees.
Do I look like I'll be happy to go through 50 different websites for 50 positions? That would be quite a time suck. Never mind that I'll be missing some pretty big websites such as google.com. Yes, I could make a persistent hot link to google.com and make quite a career out of looking for a job with Google but I'd be doing it at the opportunity cost of every other company I want to contact.
It's more efficient for me to go to a one-stop website such as dice.com or linkedin.com and go for just the positions I want. Of course, Google and others are aware of what I and others are doing and why we are doing it, which is why they have open positions on that one-stop websites.
You're complete failure as an angler if you idea of fishing is you telling the fish to come to you. I go where the fishes are and I make sure that I have at least one fishing rod set up for each spot where I think the fishes are. Google is not fishing for recruits any differently than I fish for fish.
There is or should not be any difference between you going directly to a company's website for open positions and going to a one-stop website. The reality depends on how much enthusiasm HR has for updating the company's open positions on the company's website and at the one stop website.
Having said that, if you are getting an interview with the company, that company's website may be your primary source for research on the company, which the Google search engine running a close second. If the company were indicted for example, its disclosures on its website about its days in court might be very limited.


Why is someone not allowed to see my private video on YouTube even though I have shared it with them?

Question: I have added their email address to the list of people who can view my private video. Why are they getting a notification that the video is private? I have noticed that their email address shows up as "name unavailable". Does this have something to do with it and why is it happening?
Comment: Did you find a solution for this? It's driving me crazy. I want a set of videos to appear as 'public' to the users I shared them with. (e.g. show up in searches, show on my channel, show in playlists, etc). Just ONLY to those people. I don't want unlisted.
Comment: These answers do not help. Again I'll repeat: - I make a video private - I share the video with UserA only. - UserB views my channel and sees no videos. **Correct!** - UserA views my channel **AND SEES NO VIDEOS. WRONG!!!** I **DO NOT** want to share the url with UserA! I want them to see my shared video right in my channel as if it was a public video. It's shared with them. Why do they need a Url?
Comment: @melissa Do you use and old YouTube Channel (made before 2009) and/or are you already using Google+ Circles for privacy controls?
Answer: Quote from YouTube Help about Video privacy settings:

A private video can only be seen by you and the users that YOU select.

You have to select a real User with a Google Account (formerly known as YouTube Account). This means that the eMail Addresses you select (when sharing privately) have to be the same as those used to login by their respective Users.

When YouTube is used in conjunction with a linked Google+ Profile or G+ (business) Page, then the sharing works differently. Privacy is then controlled via the Circles Feature.
Questions to ask yourself:

Have you linked your YouTube Channel to a G+ Profile or a Google+ Page?
Did you setup your Circles (to manage Contacts)?

There are 2 groups you have to understand:

Your Circles
Extended Circles

For a better understanding of how the Google+ Circle Concept works, please checkout the following links:

Read this Quick Tip: What does "Extended Circles" mean? | by +GooglePlusDaily
Who sees my posts shared with "Extended Circles" in their stream? | WebApps StackExchange
Answer: They need to have a Google account (and of course you have to send the invite to the Google account + they need to sign in to watch the video): https://support.google.com/youtube/answer/157177?hl=en

You can add the profiles or email addresses of the people with whom
  you'd like to share your video. They'll need a Google account to view
  your video.
Comment: Yes, we all have Google accounts. The main account uploads the videos and marks them private. They then share the videos to another user. The other user logs in and cannot see ANY videos in the channel. It simply does not work. We are not willing to share each video each time. I want the other user to see all videos that are shared with them which is not happening. Yes the individual link works but this is a terrible solution and won't work.
Comment: @Paul Did you share like this webapps.stackexchange.com/a/7613/18147 ?


Passing Comments for inclusion in an ABI File

Question: We are trying to pass additional information about specific actions and data field through to the abi file.   Is there a way to include comments/text in the cpp file that can be passed through and appear in the abi file?
Answer: No.
ABI is JSON file, and there is no syntax for comment in its specification.


Should governments have the power to limit the citizen's rights during wartime?

Question: Should the government be allowed to limit their citizens rights during wartime or other hard times that the country is going through? What if it was an apocalyptic event that everyone knew they would die? In what circumstances would the government be able to limit the rights of their citizens?
Comment: Related Wikipedia entries: http://en.wikipedia.org/wiki/Martial_law and http://en.wikipedia.org/wiki/State_of_emergency
Comment: The US government has not formally declared war on anyone since 1941. Yet we've been perpetually at war somewhere in the world every day since then; and we're currently at undeclared and/or secret war in six or seven countries. So I'd say no. And how do you define "wartime?" That's the problem. The US government is ALWAYS at war.
Answer: There's several ambiguities in your question that an answer needs to address. First, I am going to assume that your uses of "should" refer to moral rather than legal determinations. Otherwise, this isn't going to fit under philosophy. Second, I'm going to answer in terms of applied ethics rather than formal ethical theories. Third, I will following your question, use rights language.
Assuming citizens have rights, there are several different ways to conceive of rights. There's Isaiah Berlin's positive and negative rights distinction. On this account, negative rights where the government should not interfere with a course of action. Positive rights reflect those cases where the government or some other party is compelled to act for you. "Keep the government out of the bedroom" articulates a negative right --> to be able to sleep with whom you choose when you choose. "The government should make sure no one goes hungry" is a positive rights claim that the government has a duty to supply everyone with food.
A second distinction some draw is between first-order and second-order rights. A first-order right is something you have a direct right to. A second-order right is something that you have in light of your first order rights. So if you have a first order right to live, then you may claim a second order right that the government give you food. If you have a first order right to speech, then you have a second order right to the means of speaking. (i.e., the government cannot prohibit you from making speeches in public areas if you have a right of free speech). Actually, some take this further and speak of 3rd order rights -- but that's irrelevant for our purposes.
We need one further distinction to complete the philosophical picture. There are absolute and mitigable rights. Absolute rights are those which are of "incomparable worth" (to use a construction from Kant) whereas mitigable rights are those of "price" -- meaning they are tradeable for other things of moral value.
Given these three axes, we can give some answers.

For an absolute negative 1st order right, the government is always wrong to inhibit this right.
For any mitigable right (negative or positive / 1st or 2nd order), the government could for a sufficiently good reason abrogate its responsibility to its citizens.

After that it gets a little cloudy mostly because the philosophical pieces break down.
For an absolute positive 2nd order right, it seem possible that some conflict could prevent its execution without being immoral. imagine for instance, a right to paper and printing to build on a right to free expression. Conceivably if the government has no paper, it has lost its ability to perform this right and therewith failed in this right -- but not necessarily morally. (or to put it another way, is it possible for a right to be 2nd order and absolute? Also can there be absolute 2nd order rights? i.e. rights where the government's duty of non-interference is not immediate but is absolute? )
For an absolute positive 1st order right, it would be immoral for the government not to supply but it's difficult to understand what would qualify as such a right.
Comment: Negative rights do not emanate 2nd order such. Higher order rights are an artifact of positive "rights".
Comment: @MarcusJuniusBrutus rereading my answer it might look like I was genuinely asking. The question was meant to be rhetorical.
Answer: If a population were to face a situation of certain demise then there would be little scope in tightening a government's hand upon the rights of its citizenry. Yet even in the face of such circumstances it would be the responsibility of each person, as well as the government, to retain a semblance of the civility enjoyed up until that point.
A glance at past scenarios of wartime and disaster period chaos will reveal a great surge in incidences of looting, rape and murder. As the state loses control over order there will be those who will seek to capitalize in vain self-interest.
However there is a wide divide between serving to protect the rights of the people and seeking to limit them for the purpose of retaining control over the populace.
It may be argued that even in a situation of (relatively) non-apocalyptic events such as war, disasters, terrorist threats, and the like, that the limiting of citizens rights serves to subdue the populace and reduce morale (an essential element in facing up to the challenges represented by these circumstances).
Even the expropriation of property - and therefore the limiting of a person's right to enjoy his or her property - is a dodgy move, ethically speaking. It is a sub-ideal choice made in a dire circumstance.
However - it cannot be denied that certain choices having a negative impact upon the rights of individuals may be necessary or at least desirable in gaining advantage in dealing with the crisis (example - expropriation of land for the building of air defenses - or the claiming of crops for rationing purposes) - or the indefinite detaining of persons suspected of intending terrorist acts in detention centers.
The truth that no matter how necessary such measures 'might' be - they represent an erosion in the values practiced by the said government. In conclusion, if the values of the nation are to be valued then there should exist effective checks and balances that prevent a government from limiting the rights of citizens during crisis situations (beyond normal limitations).
Answer: Yes, they should because cooperation is important for survival, and cooperation means that one has to set aside his own anarchic impulses and obey orders from a coordinating agent.
When people's choices are between life and freedom, most people will choose life. Vast majority of people are willing to give up a lot of freedom for the sake of survival - if this proposition is taken as a governing dynamic, one would have no problem understanding why those who are in power love war, and those who love freedom should also love peace.


Dead battery or bad starter

Question: 2013 Mitsubishi Outlander. Newer battery, but car sometimes won't crank over. Then battery dies. When it gets jumped it usually starts and will start for a week or two then same problem.
Answer: Start the car and then while it is started take off the positive cable if it dies it's the alternator it kind of sounds like that could be it but I might be wrong if anything take the starter off and get it tested at a parts store you can also try when you're trying to start it and it wont crank hit the starter with a hammer not too hard tapping a bunch of times and if it starts then you know it's the starter
Comment: In my opinion it's never a good idea to disconnect the battery of a running vehicle. It doesn't prove the alternator is fully functioning.
Comment: Agree with @mikes here ... this is a bad way to do it and can fry not only the alternator (even if it is good), as well as other sensitive electronic parts throughout the car. [See my answer here about the subject.](https://mechanics.stackexchange.com/a/38927/4152)

Dead battery or bad starter


How to remove reddish brown boot dye from boots and make them a nice brown

Question: I have a pair of leather boots that are this reddish brown color. I would like to strip them and then dye them a darker tan/brown color. Any suggestions?
Answer: You can change the colour by just painting them as they are - you don't need to strip them of the colour first. But make sure you buy the dye/polish/cream which is made for the type of leather your boots are made of (that is, don't use general purpose leather cream if they are nubuck boots, for example).


What are other techniques are used to tenderize steaks apart from using a meat mallet?

Question: I'm familiar with using a meat mallet to tenderize steaks, but I'm curious what other techniques or methods there may be to achieve the same or similar results.
Comment: Should perhaps be a wiki?
Comment: Strip steaks are already pretty tender...
Comment: What is a "meat stabber?"  A tenderizer with the pyramid spikes?
Comment: Just edited it, sorry about the lame description before
Answer: Many marinades will act as tenderizing agents; particularly those that are longer-term or overnight.
The acids in the mixture will act on the meat to break it down and tenderize it.
Comment: Coke will do a job on meat.
Comment: Pineapple especially will tenderize meat due to... bromelian, I think it's called, an enzyme in the fruit,.
Comment: @squillman - I remember that as an elementary school product to keep us from drinking soda - they left meat in it for 2 weeks and it was pretty much destroyed.
Comment: @justkt heh, yeah.  I should have said "quite a job".  I used it to get corroded batteries out of my flashlight once.  A steak overnight in a marinade of Coke is, um, quite tenderized.
Answer: Acids will help to tenderize meat. Most marinades include acids -- vinegar or citrus juice. You can also use tenderizing powder bought with spices -- it's made with an enzyme from papaya. Certain cooking methods (braising, or cooking for a longer time with some liquid in a covered dish) will make meat more tender. I've read that brining meat can help tenderize it too, but I haven't tried it.
Answer: There are the meat tenderizers that do actually stab through the meat with several blades.
http://www.amazon.com/Jaccard-Supertendermatic-16-Blade-Tenderizer/dp/B001343VTY
I wouldn't use it on a steak I'm going to throw on the grill, but I've used it with tougher cuts making cube steak for things like Chicken Fried Steak
http://en.wikipedia.org/wiki/Cube_steak
Comment: For years, I just used a fork -- stab repeatedly, dip in your marinade, then grill.  I use it for the cuts of meat that you might use for london broil, as that's what I typically grill.
Comment: @Joe yes I wouldn't use this tenderizer on most pieces of meat, it is for very tough ones to break up as much connective tissue as possible not just to make a few holes for a marinade to get into. Of course, there are people that will argue holes in meat to get flavor in will inevitably just let all your juices flow out.  If it works for you though, I say keep it up.
Answer: You can get best effect using syringe. Soda niter injections are very effective.
Answer: Instead of a mallet, you could use a rolling pin. The rolling instead of hitting will treat your meat more softly for a better result.
Answer: Marinating in oil. E.g. marinating rump-steak in oil is very effective to get a nice rump-steak.
Answer: In addition to acids (to which I would add Coke is a pretty good one), I've also had some luck with Whiskey.  Leaves an extremely interesting flavor in the meat too.
Answer: Brining is my favored method. I regularly eat steaks for my diet, and I get the cheapest ones I can find. Brining turns them into restaurant quality.
Here's a great article on dry brining. To quote the scientific bit,

Salt is made of sodium and chloride ions that carry electrical charges. These ions attack the proteins, causing them to unwind a bit, a process called denaturing. These altered proteins have a greater ability to retain water, so meat that has been treated with salt remains moister through the cooking process.

Technically, it doesn't produce "similar" results to hitting it with a mallet, but it does get it soft and juicy if that's what you mean.
A lot of people know about wet brining (immersing your steak in salt water), but dry brining is easier and doesn't risk your steak getting waterlogged.

Dry your steak with paper towels or a cloth. Get it really dry.
Put about 1/6 teaspoon of table salt per kg. Simply put, it's a little more than you would otherwise would want on a steak. Some people suggest dry brining only one side, but I find that both sides work just fine.
Put it back in the fridge. Ideally, you'll want to put it the freezer on a cake rack or at least elevated a bit, to allow air on both sides. This is because the freezer has very little moisture in the air, so it'll dry up your steak.
Leave it in there for at least an hour. If you want to leave it in longer, I'd suggest putting it in the normal fridge where it wouldn't freeze up. I hear leaving it there overnight tastes better, but it's juicy enough after an hour.
Take it out. Keep it dry. Cook it.

Part of the beauty comes from how dry it is. The lack of water means no water vapor messing up your cooking. Your steak should also be moistened by the sodium. If you want to add sauces and marinades, cook it separately, though you can season it with herbs and spices. If you really want to cook your steak in water for whatever reason, brining will still soften it.


How does the Doctor recover his ethical subroutines?

Question: In the episode Equinox Part II, the EMH is operating on Seven of Nine, his ethical subroutines having been deleted. Shortly after, he appears on Voyager — presumably after being beamed over by Equinox's captain — and switches sides again. Why does this happen?
Answer: Equinox was one of the few episodes of Voyager to receive an official novelisation, in this case written by Diane Carey (who also novelised VOY: Endgame). In it we learn that before beaming the crew over to the Voyager, Captain Ransom downloaded the EMH's program from sickbay and put it onto a cartridge, with the ethical subroutines restored, which he gave to Marla Gilmore to give to Janeway to upload, presumably after they'd scanned it and found his program intact.

As Gilmore did as she was told, Ransom moved to another station. "Computer, give me access to the shield grid."
It worked. The computer was still functioning under the assumption that he was in command.
"Marla," he called at the last second, "here."
He tossed her a remote computer cartridge, especially encoded.
"That's Captain Janeway's doctor, with his ethical subroutines
  restored. When you get to Voyager, tell her the doctor over there is
  ours. Have her upload him back into their system. Her own EMH will be
  able to take back his sickbay."
Star Trek: Voyager - Equinox
Answer: The Ship's computer possesses diagnostic equipment for addressing faults in the EMH program. (Voyager episode The Swarm). They also probably contain the EMH's core essential functions such as ethical subroutines, medical knowledge, diagnostic skills and hand-eye coordination.


Can Jon be released from his vow to the Knights Watch?

Question: Jon Snow took the vow to join the Knight's Watch for the rest of his life...but he has died so that would release him. Since he came back to life he has not retaken the vow.
Answer: Jon saw himself released from his vow following his resurrection and the execution of his murders in Season 6 Ep 3. 'Oathbreaker'. He declared that 'his watch is over' before handing over the role of Lord Commander to Tollett and reuniting and riding south with Sansa to retake Winterfell in what would become 'The Battle of the Bastards'.
Answer: This was Jon's vow on joining the night's watch

"Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come."
"shall not end until my death…"

When he died and came back from death, he had technically fulfilled his vow and was no longer bound to the Nights Watch. It was a clean slate for him. So, he did a

My watch has ended

Reasons as to why he didn't join the Nights Watch

He had more pressing things to deal with and now that he was given a new lease at life, and free from his vow, he is free to deal with the real threats such as his family, avenging the losses in his family, stability at Winterfell, the Night King and Wights beyond the wall among many other things that went int chaos while he was bound by oath to the Nights Watch. This is an opportunity for him to be at places where hes actually needed and not be in a place where he can be stabbed and killed.
He was betrayed and killed by his sworn brothers from the Nights Watch and he would be stupid and broken to join in the Nights Watch again. Also people would have to have guts to make Jon stay clearly knowing he resurrected after being killed by them. He was called the "Oathbreaker" but him dying was the last straw.
The vow says "i live and die at my post", he kind of died at his post.

So it only makes sense for Jon to leave the Night's watch once he has a chance and not renew his vow after being killed by his own men


Where is a list of keycode values to use in DarkSouls.ini?

Question: Dark Souls does not allow binding of many common keys via the user interface. There are guides for the number keys, but no guides for other keys. Specifically, I have a Dvorak keyboard, and would like to bind the ['], [,], [.], and [;] keys. What are the scancodes for these keys to use in the DarkSouls.ini file? Is there a comprehensive list somewhere?
Answer: An user on Steam forums posted a link to keyboard codes for ActionScript. He tested some key numberings in the .ini file and they worked. So you might be able to use the key codes from ActionScript to configure Dark Souls.


DFA or NFA Construction

Question: I have to draw a DFA or NFA for a language that has two symbols lets say {0,1}. The condition is "such that exactly one of the two symbols 0 or 1 appears at least three times." I understood this as if 0 appears three times or more than 1 can be there for 0,1 or 2 times and if 1 appears for 3 times or more DFA fails and goes to dead state. The same will happen for the case if 1 appears 3 times or more and if 0 can be there for 0,1 or 2 times and if 0 appears for 3 times or more DFA fails and goes to dead state. I have been trying to create a DFA for this but failing everytime on condition like "01010". I am not sure if it is possible to create a DFA or NFA for this. I guess this is solvable by PDA only.
Need help in making sure that I am thinking in right direction.
Comment: There is certainly a DFA for this problem. When processing a letter, you only need to know how many of each you have already seen, capped at 3. So there are only 4*4=16 possibilities.
Answer: You only have a limited number of states to worry about:
Let note them $Q_{i,j}$ where $i \in \{0,1,2,3,4\}$ is the number of 0 and $j \in \{0,1,2,3,4\}$ is the number of 1; each up to a max of 4 $\implies$ only 25 states.
Then the transition is
$\delta(Q_{i,j}, 0) = Q_{i+1,j}$ if $i<4$
$\delta(Q_{4,j}, 0) = Q_{4,j}$
$\delta(Q_{i,j}, 1) =Q_{i,j+1}$ if $j<4$
$\delta(Q_{i,4}, 1) =Q_{i,4}$
Then the starting state is $Q_{0,0}$ and the accepting states are all $Q_{i,j}$ with $i=0 \oplus j = 1$ (where $\oplus$ is the xor operator).

DFA or NFA Construction


Realtime Anaglyphic viewport

Question: I've been trying to find if there is a way to achieve a realtime anaglyphic 3D viewport. I feel that this would be highly beneficial to a modeller by giving them a sense of depth with their model. I'm talking about one that would use the red and cyan glasses.
Are there plugins or anyway of achieving this?
Comment: Are you working on Windows?
Comment: Yep. 64 bit Windows 7
Comment: Related: http://blender.stackexchange.com/a/49105/2843
Answer: This feature was added to Blender in version 2.75a.
To enable it, you have to be in Camera View, which you can enable by pressing Numpad 0. Optionally, you can lock the camera to your view by pressing selecting View > Lock Camera to View in the panel on the right-hand side of the 3D View (N).
To enable the Anaglyphic viewport, go to the Render Layers tab of the Properties panel, and check the Views checkbox. The default settings should be sufficient:

This is what it looks like:

For more detailed information, check out the relevant Blender Manual page.
Answer: The new Multiview/Stereoscopy branch by Dalai Felinto supports many stereo formats (including anaglyph) in the viewport. You can find builds for it on Graphicall.org
Multiview is planned to be integrated into trunk by 2.68 or 2.69.
Comment: Correct me if I am wrong but the multiview branch is focused on rendering stereoscoping. There is a preview mode but you have to set up cameras and look through them. It doesn't support rotating the view in perspective mode.
Answer: iZ3D is a free driver that modifies the OpenGL library in your system to generate on the fly stereoscopic images of any OpenGL enabled application.
I've tested it with games, and is pretty realistic, in fact Need for Speed difficulty dropped to the floor using this driver.
ILStero is an open source project, haven't test it yet though.
You can use iZ3D to test you current Blender as is. Without having to built the source, so that you can see how it would improve your modeling skills.
Comment: wish it worked on linux, sounds pretty cool..
Answer: This feature is currently in development as an experimental feature. Until it is has been finished, you can download a build of Blender with it at this website.
Note that it only works in Perspective view, but of course that is to be expected.
Comment: Wow, I learned something new again :D

Realtime Anaglyphic viewport


Progress in meditation

Question: If one progresses in this lifetime, but doesn't attain enlightenment and doesn't become totally free from suffering, what can happen in future lives?
Comment: Welcome to Buddhism SE! Please note that on this site we prefer questions that are objectively answerable and asking for people's opinion is considered off-topic. Could you please rephrase your question? Also can you explain how the question title is related to your actual question?
Comment: I've edited the question to attempt to make it clearer, hopefully that's what Mariam had in mind.
Answer: Nothing is lost. However a person below the level of Streamwinner is still subject to rebirth below the level of human being. The good kamma of having made an effort will eventually surface again and bring one back to a place where practice can be resumed.
The non-streamwinner is subject to stray and unskillful thoughts that can lead to a bad destination. Should such a tendency occur at the time of death, it's: 'Have a nice day!'
The principle is something like standing at the downtown platform in the subway. Up until the time one enters a car and the doors shut one can go over to the uptown platform, but once the door has shut on the downtown train one is going downtown at least for one stop.
This is the concern when it comes to attention to death, that is that one not be thinking, as the ordinary person thinks, that ok, death will come, but some time later. One should train to think that death is a possibility as close as a breath in and out or the chewing of a mouthful of food.
See for the above idea: http://obo.genaud.net/dhamma-vinaya/pts/an/06_sixes/an06.019.hare.pts.htm
and see for the practice:
http://obo.genaud.net/dhamma-vinaya/pts/an/06_sixes/an06.020.hare.pts.htm
This is why one should strive for Streamentry. At stream entry, the knowledge is firmly fixed that 'that which comes into existence comes to an end.' This idea at that point is so vivid as to present itself at the time of death and acts as a barrier to making a foolish decision at that time, and the ball has been set rolling for an inevitable attainment of Arahantship within a period of no more than seven further rebirths in various heavenly states and among men.

Progress in meditation


Why does my lemon tree have multi-colored leaves and strange-looking fruit?

Question: The leaves on my lemon tree are yellow and white, and the fruit doesn't look normal.
Comment: Welcome to the site! Thanks for the question, I've never seen a lemon tree like that! I'm glad it was normal and not sick. I hope you stay around and have fun with us!
Answer: This plant is variegated and is likely to be Citrus limon 'Eureka Variegated Pink'.
Described by the New York Times as

A mutant found on an ordinary Eureka lemon tree in Burbank, Calif.,
  around 1930, its immature fruit has green and white stripes; the older
  fruit loses the stripes and develops flesh pigmented pink from
  lycopene, which also colors pink grapefruit. The trees are usually
  poor producers, perhaps because their variegated leaves are low in
  chlorophyll.

So there is nothing wrong with your lemon tree. It is a unique curiosity.
Comment: Good one! For better lemon production, you need another one and keep this for more ornamental uses.
Comment: Yeah. I had a Pruden's Purple tomato plant wherein part of it was variegated like that last year (that isn't typical for the variety). Your tree definitely looks variegated. I believe all Fish peppers are like that naturally, though.


Send an address in a sms to map app

Question: If a friend sends to me an address in a SMS or IMessage, for example "I am at 123 Main St" can I send that to the Map app to get directions there?
Answer: The iOS will hyperlink things such as addresses, and phone numbers, in things such as emails. If it doesn't do that, it is simple to tap and hold the address, copy it, and paste it into maps.

Send an address in a sms to map app


What we need to do exactly to move to the UK?

Question: I'm non-EU, Egyptian, and my wife is British and we want move to the UK. We been officially married for 3 years and we moved to Malta 8 month ago. Now I have a resident card in Malta, valid for 5 years as a family permit of an EU citizen.  I was just wondering if I still need to apply for a family permit to the UK from Malta, or can I just go to England and apply for the resident card there?
Answer: As the holder of an Article 10 card, you do not need an EEA family permit as long as you meet the criteria listed on the UK's page on the topic.  So you can just go to England and apply for a residence card there.


Smallest Distance-5 Quantum Error Correction Code?

Question: Is it known/proven what the smallest quantum error correction code is that can correct arbitrary two-qubit Pauli errors? I can think of the nested/concatenated 5-qubit code or a 25-qubit version of the Shor (repetition) code, but I am not sure if there are codes requiring fewer qubits.
Comment: Crossposted from https://physics.stackexchange.com/q/555303/2451
Answer: If you look in this paper, section 7, they give an [[11,1,5]] code, and show that it is the smallest you can have.
In general, for these sorts of questions, a great starting point is Gottesman's thesis. That's where I found this result stated.
Answer: Another good place to find codes with your desired parameters is this website: http://www.codetables.de/
The standard format to describe a quantum code is [[n,k,d]], where n is the number of physical qubits whose joint entangled state stores the logical information, k is the number of logical qubits encoded, and d is the distance to which they are protected.
The table is n vs k, where the distance d is the # in the box, so the smallest distance-5 code is the (11,1) entry


What is filter automation?

Question: I know what the effect of a filter on the sound of a synthesizer is, but I don't get wat the difference is between using a filter and filter automation.
Comment: when i google for the difference between these two, I can only find pages about the excel filter function. But maybe, you can help me out :)
Comment: Could this not have been answered with a simple google search?
Comment: Then it is a good question. ;-).
Answer: Automation is a feature available in most digital audio workstations and many types of similar audio production software. Automation allows a parameter like volume, pan, or mute to be changed automatically during playback of a song by the software.
In the early years of multi-track mixing, engineers had to manually move faders, and turn knobs while recording the mixdown if they wanted to make changes during the mix. Sometimes the whole band, producer, and assistant engineer would help move faders during the mixdown because there were so many tracks and so many changes that were desired.
In the mid 70's, console makers started building consoles that could change the levels automatically using voltage controlled amplifiers (the same technology used for envelope generators in synthesizers). Now with digital mixing almost anything can be automated, including settings that are part of third-party plug-ins, like a synthesizer plugin.
So filter automation is the automation of one or more filter settings. The most popular setting to automate for a synth filter is certainly the cutoff frequency. That one setting is so popular for automation that the phrase "filter automation" really refers to "filter cutoff frequency automation".
When you set up the filter on a synth, you choose a single filter setting, including the cutoff frequency, and you leave it there (assuming you don't use an envelope). With automation, you can make the filter open and close during the song, which is a very popular sound.
Skip to 4:20 in this video to see how automation is done (in Logic Pro 9) and how it sounds.
Comment: Thank you very much, now I really understand what automation means!
I posted this question, because I didn't know what was happening in the last track of [this video](https://www.youtube.com/watch?v=p-_7LUSYGtk) at 0:45.
Actually I still don't know which parameter is automated there... A cut-off frequency between 50 and 140 Hz, seems very strange. Can you help me once again? :)

What is filter automation?


What's the correct way to store fats?

Question: What are the decision parameters, when you have rendered fat to store? Glass or plastic? Refrigerated or not? I'm not looking for long-term storage; just what's the best-practice way to store it for use over a month or two?
Answer: To store fats, you should always use glass as plastics react to fats by absorbing some and perhaps discoloring or transferring flavors to your fat.  Depending on use, I prefer to work with cold fat at the start as it has a much broader possible use and I don't like to wait when I make biscuits, so I keep mine in the fridge.  However, you gain very little extra life out of keeping it in the fridge and if you don't keep it in a sealed container you run a very real risk of flavor transference there to.  If you don't make pastry dough or other such, your counter top is a perfectly acceptable place to store, as long as you use it up before it goes rancid.  One thing to keep in mind is that fats can sometimes have very different shelf lives, so make sure you taste or smell before use, regardless of storage method.
Comment: Plastic is made from oil, and the oils in your food can bond to it.  All plastics are susceptible to this to a smaller or larger degree depending on manufacture.  Under normal circumstances it merely makes it harder to clean, but it can, as stated in the answer, result in flavor transference, especially over long term storage.  This is why you could store things in Tupperware over and over again, but put tomato sauce in it just once and it will be stained for ever.
Comment: What sort of plastic is that? Most people use metal, glass, or ceramic because they are pouring off hot fat from a cooking dish, and the plastic could melt

What's the correct way to store fats?


What is the foundational book of Czerny finger exercises for piano?

Question: I've recently started teaching myself piano (via Bartok's Mikrokosmos) and feel it would be helpful to supplement the pieces with some standard exercises. Everyone I speak with suggests Czerny, but there are simply a ton of different books of his collected exercises; I'm not sure where the best place is to start. Is there one Czerny book that stands out as being particularly foundational?
Answer: Czerny Op. 599, Études, (Erster Wiener Lehrmeister im Pianofortespiel ) is usually the volume to start.
Comment: Thanks! I ended up asking a super-piano-friend who suggested the exact same volume! I appreciate the help!
Answer: I'd suggest not doing Czerny. A lot of people don't realize that the Czerny studies were written specifically as preparatory exercises for the Beethoven Sonatas. If you don't know which studies match up to which sonatas, you're not doing anyone any favors. Learn to play scales and common chord progressions. From there, I'd progress to Liszt, Dohnanyi, or Brahms technical studies. My preference is Liszt.
Comment: Pretty much all scales will have the same fingerings. Peter Feuchtwangler, who I admire very much, worked out some alternate fingerings, if you can track those down. They're very nice.
Comment: Thanks, Josh! Are there certain scales to learn, specifically, or is every scale book going to have the same fingerings in them?
Comment: I disagree that Czerny is solely for Beethoven. I only know Czerny's Op. 740 (and some etudes of op. 365). But I think this is a great book to learn a lot of technical challenges which help for various advanced works from various composers particularly also for the Chopin etudes. For example there is a study on double thirds. Afterall Czerny taught Franz Liszt, the greatest pianist of all time.
Comment: Part 2: The only thing which if I remember correctly Op.740 and Op. 365 is lacking of when compared to for example the Brahms studies are polyrhythms. I remember that in the Brahms studies there are many polyrhythms. But if you can play Op. 740 and Op. 365, I don't think you will have anymore problems with most polyrhythms...
Answer: I personally prefer Hanon but Czerny's 101 Exercises are great
Comment: Thanks, Alex! I ended up choosing Eugen's answer due to the fact that I was looking for the industry-standard. I'll for sure take a look at the Hanon, though.
Answer: It depends on what kind of music you want to play.  Czerny builds technique suitable for the classical era.  Hanon build more general finger strength and agility and is often suggested for beginners.  Oscar Peterson Etudes are great if you want to get into jazz.
Comment: Take a look at Czerny Op. 740 or Op. 365. It don't t see why these etudes are specifically for the classical era. They are etudes to play the romantic repertoire.
Answer: I use Czerny's "School of Velocity" Op. 299.
I would definetly recommend that book, it is great for building finger strength, speed, and accuracy.
They may be a bit hard for a beginner though.


How to enable multiple displays in 16.04 with ThinkPad X1 Carbon and Intel HD Graphics 520 card

Question: I am using a ThinkPad X1 with an Intel HD Graphics 520 card and have installed Ubuntu 16.04 (and upgraded linux kernel to 4.4.21). I installed ubuntu-gnome-desktop, then configured gdm as the graphics manager instead of lightdm.
Additionally, I followed the steps described here to download the Intel installer for Ubuntu 16.04, from which I updated the driver and rebooted. This did not change anything with the inability to use the second display and did not cause xrandr to begin detecting the HDMI port.
I am unable to get the system to detect a second display via any connections. I've tried through the OneLink dock via DislayPort cables. I've tried a direct mini DisplayPort to a DisplayPort on the monitor. And I've tried with an HDMI cable between the two. In all cases, I can't detect the external monitor, and xrandr only lists a single screen, 0, corresponding to the LCD screen on the laptop itself.
If I go into BIOS and I change the boot display setting so that HDMI is the boot display, then the HDMI connection does work, and the system boots and displays on the external monitor. But if I unplug the monitor, the built-in LCD screen on the laptop does not turn on, and remains black. And I still cannot detect any secondary display, not even the built-in screen.
How can I support both monitors (built-in screen and external display)? The system does not detect additional displays at all.
Previously I had tried poking around with nvidia settings and drivers, but this did not help (and let to frustrations with the nvidia driver login loop problem). It's an Intel graphics card, as mentioned earlier.
Basically, the output of xrandr --prop worries me the most, since it does not detect any other displays apart from whatever is chosen as the boot display. It should show that there is a dock DisplayPort connection, a mini DisplayPort connection, and an HDMI connection all on this machine, all disconnected (or something). But it doesn't show them at all -- leading me to believe the graphics card itself is configured in some way that only permits a single display.
Answer: This question is fairly old, but hopefully this answer helps still.
The best course is to upgrade your display drivers. Intel has upgraded their graphics updater to work with Ubuntu 16.10, however it might not work yet with Ubuntu 17.04, even with the suggested changes in the link above (my blog).
Once the display drivers are up to date, you can install the latest DisplayLink drivers. I've verified that they work with Ubuntu 17.04, but they will need a slight modification to an xorg configuration to make them responsive. You can see my results here: https://github.com/DisplayLink/evdi/issues/85
Next make sure that you have the correct cables from the DisplayLink to your monitor. You cannot use an HDMI to DP connector unless it's powered, or so I read (some other cables may support video but I haven't tried them), so the easiest method is to use a DVI to HDMI, DVI to DVI, DVI or HDMI to VGA, or HDMI to DVI. You can also use a DisplayPort (DP) to DP cable.
Make sure that your cables are securely installed. I made the mistake of having a loose connection so the monitor showed in the Displays tool but wouldn't turn on and wouldn't display video on the monitor.
For reference, my machine is a Yoga 900 with an Intel HD 520 as well. It should be a close match to OP's ThinkPad X1 in terms of hardware.
https://01.org/linuxgraphics/downloads/intel-graphics-update-tool-linux-os-v2.0.3


Could bio-luminescent plants survive in total darkness for ~3 months annually?

Question: If a three-month dark period was a normal, recurring, part of a 15-month calendar, and plants had evolved to be bio-luminescent, could they survive? Would only some survive and, if so, would it be enough to keep a large human population stable (or would there be a type of culling for the lower-class people)? Would this change if many animals were also bio-luminescent?
Comment: As Shadow1024's answer points out, the bioluminscence is pretty much irrelevant.  You need to clarify just why the plants are bioluminescent?  If you're expecting them to use it for photosynthesis, that won't work. (See "perpetual motion".)  Perhaps they've been bio-engineered by humans to provide light, in which case it depends on whether they can store enough energy during daylight periods...
Comment: Yes. Why do they shine? It can't be to provide themselves with food. What was the in-universe idea behind this?
Answer: Can a plant survive a 3 month period of no luminosity (or at least in amount that does not provide enough light to sustain any photosynthesis)? Yes, it's called WINTER, in case of polar night the tolerated period without light can be even longer.
Being bioluminesent would be quite expensive from evolutionary perspective. There would be an evolutionary pressure to drop this folly, unless there is some strong benefit for plant.
By occasion - low sunlight generally tend to mean lower temperature. That may be problem of its own.
Animals can adapt, unless such change would happen overnight, then we would face another mass extinction event, especially in tropical regions.
Humans (in A.D. 2019)? In long run it would be easily adaptable, we could squeeze much more production per hectare if the prices were higher. The tricky part would be surviving first year. I don't think that there would be any culling of low classes per se. There would be culling of livestock and food rationing, and if that's not enough, then 1st world would halt (either officially or simply by overbidding) its food exports towards third world. Even in pessimistic scenario a low class person from first country would become much slimmer, while watching on TV how people in Africa resort to cannibalism.
Comment: @VilleNiemi While local elites may see some advantages of distracting hungry masses with a minor border dispute, I don't see how would they achieve much geopolitically. As usual as in case of war for survival the morale would be high. On top of it, there also two countries with lower population but more numerous warheads, one of them even has a wide network of allies.
Comment: I am not worried about cannibalism in Africa. I am worried about the two nations with population over a billion and nuclear weapons.
Comment: Of and if it is really dark and the temperature drops, food won't matter. Even in the Nordic countries temperatures below -30 centigrade can make things fail. And it would probably get colder than that and our infrastructure could not deal with it. And that is in Nordic countries, northern Russia, Canada, few other regions... most of rest of the world would just die.
Comment: As Polish, I can assure you, that lowest recorded temperatures in my country were below -40C. Moreover, in recent years we dramatically improved quality of thermal isolation. If we get temperature slightly below -30C for 3 months the main noticeable outcome would be an outrageous heating bill.
Answer: Yes, just like plants on Earth create stores of energy in their roots to survive winter, your plants could develop a similar strategy of survival. It is also very likely that the leaves of said plants will fall off during this darkness period as leaves take energy to maintain and would not be returning energy without light.
As for human survival, the plants would not be doing much growing without an incoming source of energy, so harvesting from these plants during the darkness period would be difficult. However, humans are more than capable of preserving food ahead of time to be used throughout this period.


What is the right way to spell the title "Diana and Tom's Grill" or "Diana's and Tom's Grill"?

Question: I am looking for the most common way how people in US/Canada spell something like this, preferably in accordance with Chicago Manual of Style. What is the right way to spell the title "Diana and Tom's Grill" or "Diana's and Tom's Grill"?
Answer: "Diana and Tom's Grill" is very preferable.  This is because "Diana and Tom" act as a collective noun, such as "water" and "grain".  But I point out that "Diana and Tom's Grill" is a proper name.  As such, one could in fact use a second possessive with "Diana" and just claim it's the chosen name of the place.  In English, when dealing with proper names, anything goes.  But stylistically, English-speaking people would look at the two possessives in the name and conclude that the author was not a knowledgable speaker of English due to their failure to identify the collective noun nature of the premise in question (i.e., the grill).
Hope this helps!
Comment: I would tend to agree with the conclusion but not the reasoning: "Diana and Tom" is no mass noun. Nor am I seeing any page or section reference to the *Chicago Manual of Style.* Surely some among us have that handy, preferably the 16th edition--I do not, and therefore refrain from posting an answer.


How do I backflush my espresso machine?

Question: I just recently purchased an ECM Technika and have noticed recently that my shots have been fairly inconsistent. A friend suggested that I backflush the machine, but didn't have a chance to explain to me exactly how to do that. Can anyone tell me how to backflush my machine? How often should I do this?
Comment: Oh, and btw. Congrats on the new coffee machine. Keep it clean and be nice to it :)
Answer: Backflushing is a fairly straightforward procedure. You only need two things:

a backflushing disc
coffee machine detergent

The procedure needs repeating a few times (3-4):

Install the disc in the portafilter
Add in a bit of cleaning detergent.
Turn on the coffee machine until you hear the pump start to labour, once this happens turn the pump off, and the hot water with detergent will spray out of your 3-way valve. This is quite likely to cause spraying so try to be careful.

After you've done this, repeat the procedure without detergent to flush the soap suds from the machine.
Normally you would do this about once a month. This is highly dependant on how you feel the machine is doing, but it's definitely recommended that you do this if you use the machine a lot (Some people recommend doing it around every 30th espresso).
After this it is a good idea to run one espresso shot through the machine to clear everything out and not leave any residue.
You can find further details here
Comment: If you're going to buy / order a backflushing disk, be aware that they are also often called "blind filter" or "backflush basket". Make sure you buy the right size for your machine (58mm in case of the ECM Tecknika, and similar machines with an E61 group head).
Answer: Backflush is a very common and is not very big deal I can help you out.
but first you must understand that When we backflush we pressure release to blow cleaner up into the brewing components and The cleaner will remove the old coffee oils, dirt and deposit that causes coffee to taste bitter and rancid.
Follow these steps

Put a blind filter and add up to  3 g of teaspoon dish wash or espresso cleaning tablets and Lock your portafilter.

Trigger the brewing cycle for 10 seconds and allow the machine to release the pressure. Repeat 5-8 times, depending on how dirty your head is.

Remove portafilter. Activate brew cycle and rinse portafilter in a stream of water. Stop cycle.

Insert blind filter. Lock your portafilter into group head and now clean blind filter without the cleaner and repeat step 2 to rinse and make sure no detergent residue is left.

Make and discard a shot in espresso machine (only for detergent backflush).

Soak filters and the metal of portafilter (avoid submerging plastic handle) for 30 minutes in 1 teaspoon of detergent powder per of hot water.

Rinse with water and put filters back (only for detergent backflush).
Comment: Welcome! I strongly recommend you read [How to not be a spammer](https://coffee.stackexchange.com/help/promotion). It's absolutely mandatory to clearly disclose your affiliation - in the post, in your profile is not sufficient - lest your post gets flagged and subsequently removed as spam. For now, I have removed the link to your website, especially as it doesn't contribute anything valuable to the post.

How do I backflush my espresso machine?


Could knocking on solid objects create different pitches and notes? If so, how?

Question: Greetings, my fellow music lovers. I'm not certain if this question is on-topic but it's been bugging me for a long time. When we knock or tap our fingers on wood, or other solid objects, we make noises that almost sound like music. Well, for instance, the piece with seven notes that are played when we knock on doors, "Shave and a haircut, two bit". I know they can't make different frequencies of sound with the same piece of wood and drums don't have notes in the traditional sense, but when I picture a melody in my head and play it by knocking on my desk, it creates a somewhat similar tune with the same rhythm (due to my timing) and notes as what I have in mind. I've tried recording my noises and compared it but I'm afraid there might be some cognitive biases. Or is this simply just a psychological illusion?
Answer:
I know they can't make different frequencies of sound with the same piece of wood and drums don't have notes in the traditional sense

Incorrect. There are wooden percussive instruments with defined pitch sounds e.g. marimba. I also don't understand why you believe you can't get different frequencies from the same object. Depending on where and how you hit it, you induce different modes of vibration. E.g. in stringed instrument that's how you change the tone or produce harmonics sounds.

Or is this simply just a psychological illusion?

Perception of pitch is the domain of psychoacoustics. There is no definite boundary between perceiving certain vibrations as unpitched or pitched. Typically solid objects make sounds with continuous spectrum of multiple frequencies, but also typically not all audible frequencies have equal amplitude. Your ear may, or may not assign pitch to that sound. You can call pitch an illusion, if you wish.
Another aspect is that rhythm is a very important constituent of music. If you play a melody with a characteristic rhythm, even if pitches are only roughly correct, the melody might be recognizable.
Answer: Different pieces of wood can make different pitches.   Think of a xylophone or marimba.  The same piece of wood hit in different locations can make different pitches.  (Hit me with a practical musical example, someone?)
Sometimes you get a distinct pitch.  Sometimes just a thud. (But knocking on a small door sounds different to knocking on a large one - yes?)
Drums can definitely have pitch.  Again, some are very distinct (timpani, some tom-toms) others just more generally high or low.  You can tune your snare drum tight or loose even though there's no discernable pitch.
Comment: +1. I can't find it now, but in the early days of YouTube, I saw a drum duet with I think Chad Wackerman and Vinnie Cookies, and on racks of toms with clear heads, you could clearly read that this tom was "G" and this was "C#".
Answer: It's an interesting question. Not that interesting, but it's a slow day.
user1079505 is right in saying a melody with a characteristic rhythm might be recognizable. The rhythm of "Shave and a haircut two bits" is as well known as its tune. So the real test is, can your friends and casual acquaintances correctly identify a tune with no rhythmic interest, such as "Oh God our help in ages past, Our hope in years to come": 13 consecutive minims and a dotted semibreve? Or The Flight of the Bumble-bee with its 132-odd semiquavers? Or the intro to Purple Haze for that matter, which is, rhythmically, so like Beethoven's fifth symphony? If they can't then it's probably all in your mind.


Use zener diode as regular diode

Question: I have a circuit that uses regular diodes, and I only have zener diodes in hand. As I understand, zener will conduct after a certain voltage in reverse, so all I have to do, is pick a voltage that is slightly higher than my circuit will send to the diode, and it should not conduct in reverse, and work like a regular diode. Am I right?
Comment: I don't immediately see any problem with this, though I would recommend picking a zener voltage substantially higher than your operating voltage, not just slightly. There may be some pitfall I don't see, too.
Comment: Why substantially higher? The foward voltage need to stay in my operation range. (I don't have the spec of my diodes, picked them on ebay a while ago...)
Comment: @Eradash The Zener voltage and forward voltage are largely unrelated to one another. I say substantially higher because you want to avoid your diodes operating in the breakdown region, and it's good to have plenty of room between your normal operating state and a failure mode.
Comment: Substantially like how much? I need 5V to be passing one way, but not the other. Should I chose like 5.6V zener diode or more like 10V diode?
Comment: If you don't need a ton of diodes, consider salvaging them from something.  Can't sell warrantied product that way but it could get your project working to spec while you wait for your order to arrive.
Comment: You may be able to use a transistor as a diode also. If you have any transistors on hand. (BJT's, I mean).
Answer: If your circuit requires a small signal type diode that operates at extremely low leakage current in the reverse bias direction then a Zener diode may not be the best choice as they could have higher or lower reverse current. The only way to be sure is to study data sheets from reputable suppliers or to measure sample lots of diodes in an application circuit to ensure operation at acceptable levels of leakage.
Even though simulation is not the same as reading data sheets for worst case conditions it can shed some light on my point that you need to be careful about this. Using this simulation circuit with some common part simulation models:

You can see that the Zener as D1 has many orders of magnitude more leakage than the other two diodes. In addition to that notice that the 6.2V zener shows better under simulation conditions than the common 1N4148 signal diode.

Use zener diode as regular diode


Changing Shimano 105 triple chainset to compact

Question: I'm looking to buy a used 2015 Cube Agree GTC Race. The only drawback is that it has a triple chainset, and I would prefer a compact. Which parts might I have to replace apart from the chainset itself?
Comment: If you like the bike, buy it and ride it.  Take on some steep hills and learn to love the triple.  They're not trendy, but climbing is about gearing, and its definitely trendy to pass the haters while climbing!
Answer: To go from a triple to a compact, you generally need to switch the front derailleur for one for doubles (make sure it can be attached to your frame and the right cable pull; front derailleurs have different cage shapes between doubles and triples), the front shifter (if indexed; you need a double shifter rather than a triple shifter, and it needs to have compatible cable pull with the front derailleur) and if you're using a bottom bracket with a spindle (like a standard JIS/ISO bottom bracket, Octalink, etc.), you may need to have a different spindle length (to get the right chainline). And of course, you need the compact crankset (which is compatible with your bottom bracket).
In your case, you have a hollowtech II bottom bracket (with a Shimano road group), so you need:

Compact Crankset which fits hollowtech II bottom brackets (reasonably common; Shimano, FSA, etc. make them)
Shimano road double FD (cheap; you can get tiagra or higher for only 20-50 USD)
Shimano road double shifters (Expensive; you only need front shifter for a double, but you may end up getting  a set in which case you need to match the rear number of speeds as well).

I'd suggest trying the triple for a while -- you may end up liking it despite it not being in vogue.