types of cells in a pharyngeal specimen

Question: I would like to ask what type of cells should someone expect in a pharyngeal smear, in a person, who is infected with a viral infection. Thank you a lot!
Comment: I'm voting to close this question because it seems to be a medical question rather than one primarily about biology. This means it is not on-topic for this site. While this might be a better fit for [MedicalSciences.SE], please don't repost (instead request migration). Please consult the [tour], [ask], and other [help] pages for more information.  Thanks!
Answer: The tissue in the pharynx include:
Stratified squamous epithelium & mucus-producing glands.
However other cells that could be found would be other types of bacterial, is this what you're referencing?
Commonly scientists start with a gram stain to determine the classify the bacteria.
Gram+ bacteria have cell walls composed of thick layers of peptidoglycan. Gram+ cells stain purple when. Gram- bacteria have cell walls with a thin layer of peptidoglycan. Gram- bacteria stain pink.
The microbiome of a human consists of 100,000 billion bacteria. Therefore there are many types. E.g. Prevotella has been shown to be the most common type of bacteria in the human pharynx.
In a pharyngeal smear you would expect to find Stratified squamous epithelium, mucus-producing glands, bacteria and if a virus is present. Viral particles. This can be determined by RNA or DNA analysis.
E.g. COVID-19 is an RNA virus. If PCR analysis was completed on a sample obtained from a pharyngeal smear then we could confirm the presence of the aforementioned mammalian cells, bacteria and viral genetic material.
Comment: @Marilu, lymphocytes continuously circulate between the lymph and blood until they encounter a foreign antigen. It would be possible, but it's usually not the aim of a pharyngeal smear. A blood test would provide better results to identify how 'hard' the immune system to working.
Comment: should someone expect lymphocytes?
Comment: thank you so much!
Comment: Happy to help Marilu.

types of cells in a pharyngeal specimen


Public transportation between Agrigento to Syracuse

Question: I want to travel from Agrigento to Syracuse. I saw possibilities in Trenitalia but despite the distance being short, it takes more time due to multiple connections. Is there convenient (and cheaper) public transportation between these two cities?
Answer: I haven't been to Agrigento in 25+ years but back then there were buses to quite a few places from Agrigento. Although we took the train from Palermo to Agrigento, we ended up going back by bus, more convenient and more choices.
Answer: Rome2Rio suggests a 4h50m bus journey from Agrigento to Siracusa via Catania as your cheapest and fastest option:

Buses run several times a day and are operated by SAIS Trasporti, whose website details the itineraries and costs of all the tickets.
Alternatively, you can choose a 5h regional train journey via Caltanissetta. This itinerary is available once per day. See the Trenitalia website for options and bookings.
Finally Blablacar is a very popular car-sharing service, that works fine in Italy.


Smart lock like on Android?

Question: Is it possible to configure either LightDM or GDM to automatically log in when my laptop is connected to a certain WiFi? Or even better, to check my location regardless of what WiFi I use?
Comment: No idea, but it sounds like something you would use udev rules for - something I haven't explored yet. You could possibly write a small program and run it as a daemon as part of your startup. It could watch for the wifi connection to become active. The next problem would be what  to do about your passwords. You don't want them stored in the clear anywhere and if they end up on the command line, they will be visible in history.
Answer: I'm going to answer the question about the Bluetooth functionality that you put in the title. I don't understand how the remainder of your question about WiFi relates to that.
You can use BlueProximity to lock and unlock you desktop when a certain paired Bluetooth device is in range. Here is an article about BlueProximity on the Ubuntu forums from 2008.

Smart lock like on Android?


What is the power series of $a^x$

Question: I'm trying to find how this series is continuous by proving its infinitely differentiable. In my books, i came across the internal of convergence and the radius of convergence which should help me figure this out, but I cant seem to wrap my head around the concept of the power series to begin with, and my research generally associates this series with the taylor series; is it the same thing? can i still prove that this function is continuous everywhere through this method?
Comment: Proving a function infinitely differentiable is usually much harder than proving it is continuous.
Comment: idk i tried doing the latter, but it just didnt come easily to me. this seems comparatively easier.
Answer: Hint
$$a^x=e^{x\ln(a)},\quad a>0.$$

What is the power series of $a^x$


Duals of Left-invariant Vector Fields closed?

Question: Suppose we have the Lie group $\text{SU}(2)$. Then its Lie algebra consists of the span $$X_1 =
\begin{pmatrix}
0 & 1\\
1 & 0
\end{pmatrix}, \quad
X_2 =
\begin{pmatrix}
0 & -\mathrm i\\
\mathrm i & 0
\end{pmatrix},\quad
X_3 = \begin{pmatrix}
1 & 0\\
0 & -1
\end{pmatrix}.$$ Now, $e_i: g \mapsto L_g\vert_e(X_i) $ are left-invariant vector fields. Consider now the dual frame $e_1^*,e_2^*,e_3^*$. Are these 1-forms closed? If so, why? And even then, is it always the case for Lie groups?
Comment: The usual custom is to write $\theta^i$ or $\omega^i$ for the invariant $1$-forms. In particular contexts, people sometimes use something else. Notice that then the indices line up better, as in what @AndreasCap wrote. $d\theta^i(e_j,e_k) = -\theta^i ([e_j,e_k]) = -c^i_{jk}$.
Comment: Just a small typographical suggestion: Using an asterisk for the dual invariant $1$-forms is not an ideal notation, insofar as the upper star is used to pull back differential forms by mappings. In the context of this particular question, you're fine, but in general you'll want to switch notations :)
Comment: What would you recommend instead?
Answer: The elements of the dual frame are not closed as one-forms. By definition, each of the functions $e_i^*(e_j)$ is constant. Hence looking at the definition of the exterior derivative, you see see that $de_i^*(e_j,e_k)=-e_i([e_j,e_k])$. This is just $-c^i_{jk}$, i.e. the negative of the usual structure constants of the Lie Algebra, which are characterized by $[X_j,X_k]=\sum_ic^i_{jk}X_i$. Otherwise put, the exterior derivative on left invariant forms restricts to a mam $\mathfrak g^*\to\bigwedge^2\mathfrak g^*$ which is the dual of the Lie bracket, viewed as a map $\bigwedge^2\mathfrak g\to\mathfrak g$.


How much of what we know about ancient philosophers comes from oral literature?

Question: Have any orally-transmitted myths survived throughout the centuries in such a form that we could identify any of the ancient philosophers of Classical Greece and Rome in them? I'm interested in finding out how much could their philosophies actually affect thinking of people in the Middle Ages.
Comment: Can you provide a working definition of "oral literature" in your question so that people reading your question do not make the assumption that they are dealing with an oxymoron?  It's not that common of a term.
Comment: "Antic philosophers"?  Do you perhaps mean antique philosophers, in the sense of Classical Greek & Roman philosopy?  Antic philosophers conjures up all sorts of interesting mental images :-)
Comment: "orally-transmitted myths" about "ancient philosophers" ? We have *text* from ancient Greece philosophy that influenced MA: Plato, Aristotle, pseudo-Platonic and pseudo-Aristotle.
Comment: @Probably: in that case, doesn't Socrates apply? He never wrote a thing, but was deeply influential. Also, the question could use some rewording, as it really isn't so clear what you're after.
Comment: @SeligkeitIstInGott No, I meant [oral literature](https://en.wikipedia.org/wiki/Oral_literature).
Comment: @Probably I truly hope a subject matter expert on the ancient world and Medieval times comes by and can answer that question about oral tradition or legends that survived about the philosophers specifically. If I encounter anything by way of research in the future I'll update my answer. However, perhaps the best I can do for now is to reference you to another forum. If you are on Facebook there is an excellent group called "Nerdy Classics Majors" who live and breathe to answer questions about the classics and many are versed in Attic Greek and Latin. You might get some helpful responses there.
Comment: But also some "forgeries", like the [Corpus Hermeticum](https://en.wikipedia.org/wiki/Hermeticism).
Comment: Don't the Old and New Testaments qualify?
Comment: There are also the *gathas* of Zarathrustha, the *Upanishads* in India and given how important Homer was to the Greek cultural life, then Homer.
Comment: @DenisdeBernardy Sorry, I only meant the philosophers of the Ancient Greece and Rome,edited the question.
Comment: @MoziburUllah I only meant the Greek and Roman philosophers, I edited the question
Comment: When I read Diogenes Laertius's *Lives of the Philosophers* I got the impression that a great deal of his knowledge was derived from unreliable oral tradition, and that tidbits about his subjects' idiosyncrasies were much more like survive than technical expositions of what his subjects actually thought.
Comment: @Probably I gave, and just expanded today, an answer below. Please let me know if this is/isn't the direction you were hoping to take your inquiry.
Comment: I too am actually a little confused at what you mean by "oral literature". If you mean literature that was eventually produced about a person based upon the oral transmission of things claimed about a person and what they said, then I think I have understood your intent.
Comment: @Probably Hmm, okay, that terminology is new to me. Very interesting. Discussions of the "orality of literature/texts" are common in academic discussions about ancient works especially when trying to reconstruct a theoretical pre-textual oral form (often in conjunction with the concept of 'Sitz im Leben') that contributed to the form of the written text, and so my first assumption upon seeing "oral literature" was something closer to that. But thank you for the clarification. I'll have to keep that terminology in mind in future reading.
Comment: I'll be glad for any other views, don't think either answer answers my question.
Comment: You may also want to go out on a limb in your OP and give an example of what you hope or expect to find, like "I wonder if Medieval royal court poets like Chaucer slightly embellished the Greek philosophers to resonate with English imperial themes of the period." Honestly, I tried my own suggestion of hitting journals & search engines just now and am finding very little on such a broad topic. I noticed that "humanism" kept popping up as well as art & theater (oral) as preservers of themes from antiquity. Tell me if this helps at all (3rd pg citation of Walter Ong): https://tinyurl.com/y9lbhjms
Answer: I think you want to start by reading a little Dante.

Here I saw Socrates and Plato, who in front of the others stands
  nearest to him; Democritus, who ascribes the world to chance;
  Diogenes, Anaxagoras, and Thales; Empedocles, Heraclitus and Zeno; and
  I saw the good collector of the qualities, Dioscorides, I mean, and I
  saw Orpheus, Tully and Linus and moral Seneca; Euclid the geometer,
  and Ptolemy, Hippocrates, Avicenna, and Galen, and Averrhoes, who made
  the great comment.
   - Inferno, Canto IV.

Dante clearly expected his audience to know who these people were.  Which tells you that as of about 1300AD, people had some smattering of knowledge - and not just the educated monks, but the general audience that Dante was writing in vulgar Italian for.  Dante assumed the burghers knew not just of the names of the philosophers, but a bit about their most influential ideas.
We can only guess how much of this written literature was influenced by the oral literature of the era, or how it seeped into the oral culture that followed.  But Dante wrote in verse for a reason - it was written to be read aloud and perhaps to be memorized and passed on orally.  It seems hard to imagine that Dante's works were isolated from the oral literature of the time.
Comment: If Dante has been writing just for monks, would he have written in Tuscan?
Comment: @DenisdeBernardy: Not a *typical* villain agreed; but an *upwardly mobile* villain and the burgeoning *middle class* that would soon fill the Globe Theatre in London to enjoy Shakespeare & Marlowe most certainly yes.
Comment: Are you sure this isn't hand waving the context of the times away? Dante lived in a period where Europeans were soaking antiquity's literary classics out of Sicily and Cordoba. And the few literate elites and monks of the time would have been familiar with these names, if only because there wasn't that much else to read. Methinks there's very little chance your average villein would be familiar with these names.
Answer: Edit: Now that the OP question has been reworded for clarity I will tip my hat to pokep as being closer to answering the intent of the inquiry. It was not clear to me originally where orality and myth came into the picture with literature in the question. Nonetheless, I'll leave my answer here in case it helps anyone.
I'm afraid you're probably not going to get away without doing some research of your own on this, but perhaps some pointers could help. Firstly, since you give such generous leeway with respect to the period of time under consideration (from the lifetimes of the ancient philosophers up to the Middle Ages) I feel at liberty to jump around a little bit.
Firstly, from your title alone ("How much of what we know about ancient philosophers comes from oral literature?") I immediately thought of the matter of Socrates and what we know of him and how we know it. We have no writings from Socrates himself, and are dependent largely on Plato for telling us what Socrates taught. That in itself presents us with a dependence on orally transmitted details about a person of a truly ancient provenance (almost from the get go). So oral transmission of knowledge about a person need not be something long after the fact and also need not be inherently suspect or inaccurate.
It seems ironic, however, that the historicity (existence) of Socrates as a person and the essential content of his teachings are rarely called into question, despite us having no written records from him personally; yet all the while some "mythicists" call into the question the historicity of Jesus of Nazareth and his essential teachings (which also relies on sources that provide orally transmitted details from early witnesses who knew him personally, rather than from any direct writings by him). The same can be said for Siddhārtha Gautama (Buddha). There are good reasons to regard them all as real historical figures whose teachings have reached us accurately by their ancient witness-bearers who wrote them down.
To take one ancient example from the Hellenistic world, the fields of New Testament studies (in the case of Jesus and early Christian history - as Koine Greek speakers and/or writers), Orality, Textual Transmission, and Historiography are all even disciplinarily related - resting upon the same historiographical foundations and inquiries - to this same question you raise about orally transmitted details of ancient figures and their teachings. The questions and methodological principles for analyzing such orally transmitted accounts (especially in such a largely oral culture) applies equally to New Testament studies and the study of any Greek or Roman literature or historical sources in general. So studying orally transmitted details about Greek Philosophers will involve the same interdisciplinary considerations to determine historicity.
The field of study on those topics of orality and historiographical textual studies is vast, and I have seen much discussion of it in NT studies (which is why I mention it), and no doubt broader studies on Greek literature and historical sources may be found which would apply to Greek Philosophers. I would just recommend spending time on a search engine, journal aggregate sites like JSTOR (which now provides some limited free access), or book catalogues such as WorldCat searching for keywords like "Orality" and "Greek literature" or "Greek History" (Substitute "Hellenistic" for "Greek" where appropriate) and start where you can.
Further, aside from such foundational matters, if you wish to find a good compendium of ancient knowledge about all manner of elements of Greek and Roman culture and language as understood by a later civilization, the Byzantines, then I recommend doing some research on the Suda. This may help bridge the gap from classical times to the Middle Ages, as you discussed. As Wikipedia states the Suda "is a large 10th-century Byzantine encyclopedia of the ancient Mediterranean world". It is part lexicon and part encyclopedia but presents a broad understanding of knowledge of the classical world, and may provide you some clues for what you endeavor to research. I often see it cited in academic literature when someone is debating the meaning of Greek words in classical literature (often as applied to exegetical analysis of Greek texts), but it also provides some details of ancient knowledge and facts as understood at the time. As the Wikipedia article states:

The articles on literary history are especially valuable. These entries supply details and quotations from authors whose works are otherwise lost.4

One Byzantine churchman and scholar who wrote widely on Greek classics and also made reference to the Suda was Eustathius of Thessalonica. In the Encyclopedia of Ancient Greece by Nigel Wilson (pg. 60) it says:

Noted Classical scholars such as Michael Psellos and John Italos in the 11th century and John Tzetzes and Eustathios of Thessalonica in the 12th did not confine themselves to the copying and editing of ancient manuscripts but became the self-appointed exegetes of the Classical tradition, writting essays and commentaries in a broadly "Classical" style, albeit from a Byzantine perspective, and using ancient texts to reflect upon contemporary and often ecclesiastical issues. During the Palaiologan period (13th century on) there was a revival in Classical philology and many Greek texts owe their survival to the efforts of Planudes in the 13th century and Triklinios in the 14th.

Without you narrowing down your inquiry further though it is tough to know what specific areas to hit upon. However, those topics about Socrates, the Suda, and later Byzantine Greek scholarship were the first things to come to mind when I read the OP. Perhaps this will be of some assistance.


ZeroC ICE vs 0MQ/ZeroMQ vs Crossroads IO vs Open Source DDS

Question: How does ZeroC ICE compare to 0MQ? I know that 0MQ/Crossroads and DDS are very similar, but cant seem to figure out where ICE comes in.
I need to quickly implement a system that offloads real-time market-data from C++ to C#, as a first phase of my project. The next phase will be to implement an Event Based architecture with an underlying Pub/Sub design.
I am willing to use TCP.. but the the system is currently running on a single  24 core server.. so an IPC option would be nice. From what I understand ICE is only TCP, while DDS and 0mq have an IPC option.
Currently ,I am leaning towards using Protobuf with either ICE or Crossroads IO. Got turned off from the OpenSplice DDS website. Ive done lots research on the various options, was originally considering OpenMPI + boost:mpi, but there does not seem to be MPI for .NET.
My question is:
How does ICE compare to 0MQ? I cant wrap my head around this. Was unable to find anything online that compares the two.
thanks in advance.
........
More about my project:
Currently using CMAKE C++ on Windows, but the plan is to move to CentOS at some point. An additional desired feature is to store the tic data and all the messages in a "NoSql" database such as Hbase/Hadoop or HDF5. Do any of these middleware/messaging/pub-sub libraries have any database integration?
Comment: While persistence in a MQ library isn't unheard of, database integration in your messaging layer sounds awkward. Don't worry about that, embrace distribution instead. Subscribing to your tick data publisher and storing the input to a db makes for a nice, self-contained app.
Comment: It could be thought of like this: ALL messages from a session need to be resent in the event of any downstream app crash and restart.. so it can be thought of a long "message transaction", that if not fully completed.. would need to be resent.. so there is some logical way to say that the messages layer should resent all messages "missed" when an app starts up. but i agree w you.
Answer: Some thoughts about ZeroC:
Very fast; Able to have multiple endpoints; Able to load balance on the endpoints; Able to reconnect to a different endpoint in case one of the node goes down. This is transparent to the end user; Has good tool chain (IceGrid, IceStorm, IceBox, etc); Distributed, high availability, multiple failover, etc
Apart from that, I have used it for hot swapping code modules (something similar to Erlang) by having the client create the proxy with multiple endpoints, and later on bring down each endpoint for a quick upgrade one by one. With the transparent retry to a different endpoint, I could have the system up and running the whole time i did an upgrade. Not sure if this is an advertised feature or an unadvertised side-effect :)
Overall, it is very easy to scale out your servers if need be using ZeroC Ice.
I know ZeroMQ provides a fantastic set of tools and messaging patterns and I would keep using it for my pet projects. However, The problem that i see is that it is very easy to go overboard and lose track of all your distributed components. This is a must have in a distributed environment. How will you know where your clients/server are when you need to upgrade? If one of components down the chain does not receive a message, how to identify where the issue is? the publisher? the client? or any one of the bridges (REP/REQ, XREP/XREQ, etc) in between?
Overall, ZeroC provides a much better toolset and ecosystem for enterprise solutions.
And it is open source :)
Answer: Jaybny,
ZMQ:
If you want real good performance and the only job for Phase 1 of your job is to move data from C++ to C#, then Zmq is the best option.
Having a pub/sub model for event driven architecture is also something that Zmq can help  you with, with its in-built messaging pattern.
Zmq also supports your IPC requirements in this case. Eg: you can have one instance of your application that consumes 24 cores by multithreading and communicating via IPC.
ZeroC Ice:
Ice is a RPC framework very much like CORBA.
Eg.
Socket/ZMQ - You send message over the wire. Read it at the other end, parse the message, do some action, etc.
ZeroC Ice - Create a contract between client and server. Contract is nothing but a template of a class. Now the client calls a proxy method of that class, and the server implements/actions it and returns the value. Thus, int result = mathClass.Add(10,20) is what the client calls. The method, parameters, etc is marshalled and sent to the server, server implements the Add method, returns the result, and the client gets 30 as the result. Thus on the client side, the api is nothing but a proxy for a servant running on a remote host.
Conclusion:
ZeroC ICE has some nice enterprisy features which are really good. However, for your project requirements, ZMQ is the right tool.
Hope this helps.
Comment: In terms of raw performance, ZeroC ICE is very fast. For most cases this should be enough. If however, your needs are sub millisecond, low latency, etc then ZMQ is a better choice.
Comment: I wouldn't say that ZeroC Ice is "much like CORBA", see http://www.zeroc.com/iceVsCorba.html
Answer: For me.. the correct answer was Crossroads I/O . It does everything I need.. but still unable to  pub/sub when using protobufs... im sure ZeroC ICE is great for distributed IPC, but 0MQ/Crossroads, gives you the added flexibility to use Inter-Thread-Communication.
Note: on windows, 0mq does not have IPC.
So, all in all, the crossroads fork of 0mq is the best. but you will have to roll your own windows/ipc (or use tcp::127..) , and publisher side topic filtering features for pub/sub.
Comment: It seems like Crossroads I/O ceased development back around July, based on a comment that the creator has abandoned it for a new project, and the cessation of commits to the main repository.
Comment: nanomsg is the new crossroads
Comment: Thanks for sharing! You say Crossroads (vs ZMQ) is the best fork, have you seen any specific differences (stability/features etc.) or is that conclusion more based on available community/support? I am currently looking into a similar solution myself.
Comment: Crossroads I/O is clean and bug free. It provides the basic messaging functionality w/o all the fluff. I'm using it in production and plan on contributing in the future. Think of Crossroads as a minimalist 0MQ.
Answer: nanomsg, from the guy who wrote crossroads and 0mq (i think).
http://nanomsg.org/


Is this a green Wandering Jew plant?

Question: I think I may have inherited two of these green wandering Jew plants... but I can't find any description of the tiny white flowers that it's putting off... does anyone have any pics of this variety of jew's flowers?
Comment: How fast do they grow? The wandering Jew that I had, which looked like yours (although I never got flowers) grew quite fast in a south window, and was easy to root in water quickly.
Answer: wandering jew flower
Your plant most certainly looks like a wandering jew...it could also be a few other plants...really need more information about this plant.  Looks like you've used potting soil in that pot, is that right?
What window is supplying the light?  How close is this plant to the window?  How are you watering?  How about fertilizer?  How was this plant taken care of before you became caretaker?  It looks healthy but you'll need to give it fertilizer after a while and it is good to know what this plant is used to getting.  Is it in its original soil?  Or did you transplant it, them?
Wandering Jew looks like to me...is this your first house plant?
White flower is normal, that flower should develop into the flower pics I sent...
Comment: It looks like the kind I used to have. What other plants did you have on mind, stormy?
Comment: baby salal?  not remembering the name at all but depending on the scale, this could be the...minor salal?  There is another one that is actually a plant for aquariums that has been let loose somewhere...does fine in bogs...I have babied a purple dark violet purple wandering jew, propagated it for friends, that was breath taking.
Comment: Bulbs or corms? Little blue flowers? I've a 30's groundcover run wild that looks a lot like your photo. If so, dig the stuff up, or it will soon be everywhere.
Answer: I am pretty certain that's a variety of wondering jew.  They like plenty of light and water, you can also root from cuttings in water.  One thing to caution you on, they are an invasive plant, if planted outdoors in warm climates, they tend to take over.

Is this a green Wandering Jew plant?


What exactly do math education PhDs do?

Question: I have been researching this for the past hour or so, but I have not really found a sufficient answer.  What I have found is that vaguely, math education PhDs set policies for math education.  However, universities almost uniformly have math professors teach mathematics courses.  I believe that usually the math professor runs his course the way he wants to.  Do their policies affect the university level, and if so, why do math professors teach the courses instead of math education professors?
Comment: I guess that math education PhD mostly study school level (K12) math education.
Comment: There are two kinds of math educators–the few who are/were researchers and the rest who have never been. The lectures by the first group were usually some of the best I have seen, while the second group classes I can easily call the worst ever taught. Comparing to school education, university students do not need that much guidance and self study plays a greater role; courses are more though-intensive and lecturers need deep subject knowledge and area experience. In other words, the qualities of math educators don't shine there, but the disadvantages show easily (one has only finite time).
Comment: Probably a perfect question for the under-construction [Math education](http://area51.stackexchange.com/proposals/64216/mathematics-learning-studying-and-education) site.
Comment: I'm voting to close this question because it belongs on another site: https://matheducators.stackexchange.com/
Answer: Having a PhD in anything doesn't suddenly make you into anything. Lots of people with Mathematics PhDs don't work in universities and don't do mathematical research.
People who have a PhD in mathematical education will have spent time researching mathematical pedagogy, more often than not, at pre-university level. In the UK, people who have done this are then often involved in teaching and training those who are training to be a school teacher.
Academic reform, e.g. introducing new curricular, is often done by panels of maths teachers, maths professors, politicians and educationalists.
Answer: Example.
Someone (probably the salesman) says: Student clickers!  the greatest thing for low-level large lecture math classes since the invention of the overhead projector!  So, the math education PhD (Professor Z) sets up a study.  Some classes done with clickers, others without.  Pre- and post-testing, to see what the students learned, and the students' impressions of the two methods.  Publish in a math education journal.  Get kudos from Professor Z's department (maybe a raise or a promotion).  Whether it will influence anyone in deciding whether to adopt the use of student clickers: that's another problem.
Comment: So math education is a social science?
Comment: Excellent example thanks!
Answer: Actually the answer is very clear. Math professors deliver their mathematics knowledge. They are good at math, not necessarily good at pedagogy.
Math educators research about how can learners learn math more effectively. We observe, work with data, use research designs, do statistical analyses, etc. to develop/contribute to theories about learners, teachers, context, teaching methods etc. Doctoral degrees differ too:
EdD: focuses on teaching and learning
PhD: focuses on research on teaching and learning

What exactly do math education PhDs do?


How do I remove the Enderdragon from the normal world?

Question: So I accidentally spawned the Enderdragon in my normal world using the Single Player Command "spawn random".  Can I use any single player commands to remove this Enderdragon (or is there any other way)?  It is currently destroying all my hard earned creations.
Comment: Have you tried killing it?  It's really not hard at all - I did it my first time with a few wooden swords and no armor, without dying.  If you attack him when he gets near you, he doesn't hurt you, he just sort of pushes you *(which I'm assuming is a bug)*
Comment: @BlueRaja-DannyPflughoeft Unfortunately I'm within a massive underwater city connected by corridors. The dragon is impossible to fight, it just destroys a module and swoops out of range!
Answer: <code>/kill @e[type=ender_dragon]
</code>
This actually won't kill the dragon, but rather delete it outright (which means it will not drop experience).
Alternatively, you can do this instead:
<code>/gamemode creative
/give @p netherite_sword{Enchantments:[{id:sharpness,lvl:255}]}
/effect give @p strength 600 255
</code>
… which switches you over to Creative, gives you a Sharpness 255 Netherite sword and a Strength buff. Fly up to the dragon and bonk it with the sword.
Comment: Thank you! /killall EnderDragon worked great. Now the rebuilding begins..


alignment in applet

Question: how can we align the variois interface component(such as label, textfield, button) in applet??
As for instance i want 4 label and a button in an applet, in which all the component should be in different line?? how can we do it??
Answer: Use Layout Managers in java to align components depends on various order. for reference try this link
and for your own position there is an layout manager call null layout (example)

alignment in applet


Meditation timer that reports mindful minutes to the Health app?

Question: Is there a simple meditation timer app that actually logs time spent meditating to the Health app as mindful minutes? I need just a simple timer, no guided meditation (and certainly no subscription). Preferably an Apple Watch app?
Answer: Sattva - Meditation Timer & Tracker
Sattva is the world's first advanced meditation timer and tracker with challenges, trophies and guided meditations to inspire you to meditate everyday!
Has the features you requested:

Apple health kit integration for mindfulness (minutes)
Apple Watch app
Comment: Thanks--it works! (I sent the developer of the other app an email, maybe they will fix the problem. I think I actually liked that one better--simple and uncluttered. Sattva has an Apple Watch app tho. Anyway, thanks again!)
Comment: Whoops: when you meditate with the Apple Watch Sattva app it doesn't record the time, only the iPhone app. Timeless works correctly from the watch and the phone.
Comment: See [below](https://apple.stackexchange.com/a/303493/23813): Timeless doesn't actually work the way I'd like either, but Meditate (Watch) does.
Answer: After many months of trying different apps, the one that best addresses what I need is Timeless. Sattva does not log meditation time when you meditate on the watch. Timeless does, though you have to open the iPhone app after meditating to get it to log the time.
I'll just editorialize a little and say that it's crazy that, in the Mindfulness section of the Health app, Apple promotes a bunch of apps that don't record mindful minutes.
Answer: Meditation Timer and Log
This free app is for anyone who enjoys meditation. It's lightweight, simple to use and has bubbly feeling to lift you up. Practice meditation in the way you like it, and we will help you to personalize and keep track of your meditation activities.
In the latest update it added: "Integration with Apple Health".
Comment: This is a nice app. However it has a fatal flaw (bug?): it saves meditation sessions to the Health app as Workouts, not Mindful Minutes!
Answer: I can really recommend Samsara, https://itunes.apple.com/us/app/samsara-timer/id592333521?mt=8. It's a meditation timer without distractions, and yet it has enough options to customise. If you use it on your iPhone, it will automatically log your meditation as Mindfulness Minutes in Apple Health.
Answer: The app I'm currently using is called Meditate (Watch). The developer emailed me and explained the situation: the only way an app can stay foremost and running on the watch is to open an Activity. That's how all the other apps work.
Meditate is different: you start a meditation, and the app runs a timer. When the meditation is complete, you get a notification on the watch, which you tap to re-open the app and save the session.
The downside of this is that you can't glance at your watch and check your progress while you meditate. The upside is that it correctly stores mindful minutes without recording to the Activity app. FTW.
The app is very simple and elegantly designed, and I find that it works great for me. I use Streaks to motivate me to keep meditating, and these two apps communicate automatically through the Health app data. Recommended!


Reference for introductory Lie Groups

Question: I am currently learning about Lie groups,So kindly suggest a reference for Lie groups, which contains lecture on Manifolds as well.
Comment: I found Warner's book "Foundations of Differentiable Manifolds and Lie Groups" to be good. Although I haven't looked at the chapters on basic manifold theory.  Lee's "Introduction to Smooth Manifolds" also has some basic Lie groups stuff. His books are very well written in my opinion.
Comment: I would recommend the Naive Lie Theory by John Stillwell https://www.springer.com/gp/book/9780387782140
Answer: The best book I found on the basics of Lie theory is Structure and Geometry of Lie Groups by Hilgert and Neeb, which for some reason is not very well known. It contains a chapter on manifolds, but if you never studied them before it might be a bit rushed. It barely has anything on semisimple Lie groups, though (only the Cartan and Iwasawa decompositions, without the classification of all semisimple Lie algebras and groups using root systems).
I agree it's probably better to study manifold theory first, and I definitely recommend John Lie's book Introduction to Smooth Manifolds (although it contains much more than you need).
After studying manifold theory separately you can get back to Hilgert & Neeb's book. Also there is a book by Kirillov and a book by Varadarjan (which actually also contains a chapter on manifolds, but it is definitely  too brief if you haven't seen it before); both books are nice. They're less friendly than Hilgert & Neeb, but they go deeper into the theory of Semisimple Lie groups (or at least semisimple Lie algebras in Kirillov's case).
If like me you still don't feel comfortable with manifolds even after you learned about them separately, though, I don't recommend Varadarajan's book. He goes deeper into their theory than Hilgert & Neeb (and Kirillov).
There is also the book by Knapp. It is nice, but only if you already know the elementary theory of Lie groups (say by reading chapter 9 of Hilgert and Neeb).
Two other common recommendations are Warner's book and the book by Onishchik & Vinberg. Warner book is written pretty nicely, but he goes way deeper into differential geometry than you need, and it barely contains anything on Lie groups other than the extremely basic stuff (although it probably contains enough to start reading Knapp's book).
Onishchik & Vinberg's book is (in my opinion) very hard. In order to read it you need to be prepared to read at a very slow pace and solve all the problems (otherwise you won't really understand it). Also, you will have to study the theory of manifolds separately for the first chapter, and it is probably a good idea to study algebraic geometry and algebraic groups separately in order to understand chapters 2-3, which are necessary for chapters 4-5. If you're willing to do all that (and have like a year to spare for it), than it will be great for you. He covers the basics of Lie groups, algebraic groups, and semisimple (complex or real) Lie groups.
Answer: I think if a book's goal is to cover Lie groups, then a prologue on manifolds often feels rushed and you get a watered-down version. You should take a good book on Lie groups and hold it next to a good book on manifolds, and switch between them when you need to look something up.
For manifolds I can easily say Smooth Manifolds by Lee is great. For Lie groups I think it's a bit harder ... Good books are by: B. Hall; Brocker and van Dieck; and Fulton and Harris. (Just look up the author's name with keyword "Lie groups".) Fulton/Harris does a lot on Lie algebras that you might not be interested in, but it's useful to have it as a reference to get a full picture of the theory.

Reference for introductory Lie Groups


Present Perfect Continuous "Has been she talking ?"

Question: "Has been she talking on the phone ? " Is it correct ?
Answer: Has she been talking?
Subject---> Verb is standard english format.
"Has" being the question word, she is the subject, and "Been talking" is past participle + gerund, The subject will always precede the verb.
Answer: No.  "Has she been talking on the phone?" would be correct.
Answer: In a yes/no question, the first item is the first word in the verb phrase.
Your verb phrase is 'has been talking'
Place the first word of this phrase, (has) first.
Next add your subject, (she).
Then simply finish the verb phrase followed by any other elements.
Look at this example of a very long verb phrase and notice where I place the first two items of the question.
Jake could have been sleeping.
Could Jake have been sleeping?
I hope that helps.


How to install JDownloader 2?

Question: There still isn't any post here in AskUbuntu about how to install the JDownloader 2 yet, so I decided to write this one. I googled a way to, and found one, but I sincerely think that there might be other ways, so I hope that you will share instructions for other ways to install it.
Comment: Btw, is the `add-apt-repository` better than installing from a silent installer script? I don't know the diferences.
Comment: Also, I can't create new tag `JDownloader2`. I'll let the community to decide wether or not to create the new tag; please change this question's tag if the new tag is created.
Answer: Firstly, get the silent installer script for your system type.
For instructions on how to check your system type, read this.
Open your terminal by typing Ctrl+Alt+T then type or copy&paste the following command:

32-bit OS:

wget http://installer.jdownloader.org/JD2SilentSetup_x86.sh

64-bit OS:

wget http://installer.jdownloader.org/JD2SilentSetup_x64.sh
Wait untill the download finishes, then give it executable permission and run it (don't forget to change JD2SilentSetup*.sh to the correct file name):
chmod +x JD2SilentSetup*.sh
./JD2SilentSetup*.sh

It'll bring up the install wizard. Follow the instructions and it will install automatically for you.
Thanks to Ji M for posting instructions on UbuntuHandBook.
Thanks to @MemPrices for letting us know that the necessary Java packages come built in the SH installer, so users don't have to install it beforehand.
Answer: I woul like to tell you that actually any SH installer of JDownloader has its own Java Version, independent of the one you have installed into your system. So, basically, There's no need to pre-install Java before running the installer.
Nice day!
Comment: Hello, thank you for sharing this with us! I'll edit my answer, but can you also share any source? I can't look for it right now :(
Comment: Hi. I've confirmed it, it has a folder called `jre` in it and apparently has everything inside it. In case someone is concerned about it, I'll test if it works without preinstalling Java, when I have some more time to.
Comment: I've confirmed this and editted my answer. Thanks a lot!
Answer: One improvement though, as you pointed out in earlier posts, jDownloader 2 has a Java jre/ folder bundled with it, which size is ~ 147 MB. This is not useful in any Ubuntu distribution. Debian / Ubuntu provides java-7-openjdk packages that will be shared by all applications using Java. You may have installed as well Oracle java 7 or 8 from packages build by webupd8.org Install Oracle Java 8.
OpenJDK can be installed via Ubuntu's package system by running this command:
$ sudo apt-get install openjdk-7-jdk icedtea-7-plugin
Function of each package:
openjdk-7-jdk     OpenJDK Development Kit (JDK)
icedtea-7-plugin  web browser plugin based on OpenJDK and IcedTea to execute Java applets
These packages are installed in /usr/lib/jvm then you will see folder java-7-openjdk for OpenJDK and java-7-oracle or/and java-8-oracle for Java Oracle. Each of these install do have a jre/ folder.
In addition the Java version used by default in your system should be defined (system wide for all users) in the file /etc/profile e.g. for java-7-openjdk
JAVA_HOME=/usr/local/java/jdk1.7.0_09
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
JRE_HOME=/usr/local/java/jre1.7.0_09
PATH=$PATH:$HOME/bin:$JRE_HOME/bin
export JAVA_HOME
export JRE_HOME
export PATH

You may have to add or edit it, as the Ubuntu system uses update-alternatives to switch between installed versions of Java. These symbolic links are not per jre/ folder but per executable file i.e. java javac ...
Then you have to edit the Bash launch script jd2/JDownloader2 located in your home folder (echo $HOME in a Terminal), to add the following line as the first line of code below the comments ending #INSTALL4J_ADD_VM_PARAMS=
INSTALL4J_JAVA_HOME_OVERRIDE="$JAVA_JRE"
Or if you didn't define the jre/ folder
INSTALL4J_JAVA_HOME_OVERRIDE="$JAVA_HOME"/jre
Afterwards you can remove the bundled jd2/jre folder. That would save you ~ 147 MB and have your Java JRE managed by the Ubuntu system.

How to install JDownloader 2?


2-4 Tree Max/Min number of nodes

Question: I'm trying to learn about 2-4 trees and came across a question I have no idea about, and google hasn't been very helpful either. What is the maximum and minimum number of nodes for a 2-4 tree?
Answer: 2-3-4 trees (same as 2-4 tree) are essentially B-trees of order 4, the minimum number of nodes is 1 and the maximum... well, how much data do you wish to store in one? Check out the link for more info:
http://en.wikipedia.org/wiki/2%E2%80%933%E2%80%934_tree
EDIT: P.S. Google is your friend and sorry for reactivating a dead post...

2-4 Tree Max/Min number of nodes


What is the equivalent of audacity for iPad?

Question: I'd like to edit sound files on my iPad with my daughter - copying and pasting clips, zooming in to see sound waves, and speeding up and slowing down sections of audio.
My question is: What is the equivalent of audacity for iPad?
Comment: It's called the music section of the AppStore - look there. You should find what you are after.
Answer: The currently-accepted answer, WavePad, seems to be sporadically unavailable on the App Store (at least in some regions). I haven't found another suitable alternative. Also, some would not agree a proprietary product—especially one requiring payment to unlock all features—is actually an "equivalent" to open-source Audacity.
However, there is new reason to hope for Audacity on iPad: it appears the technical obstacles cited by the Audacity team for the lack of iPad support are disappearing.
As of this writing (April 2021), the Audacity FAQ includes the following:¹

Current versions of Audacity work internally with uncompressed audio to permit high quality editing with a wide range of effects. This requires more processing power and disk space than is available on most mobile devices. Also the wxWidgets interface library we use only has limited support for mobile operating systems and small screen resolutions.
Therefore, considerable rewriting of Audacity and its interface will be required before Audacity will work on portable music players like iPod, smartphones like iPhone, tablet computers like iPad or any of the Nexus devices running Android.
However, Audacity in principle does support a tablet PC running Windows (including Microsoft's "Surface with Windows 8 Pro" tablet)…

As of 2021, some new iPads and Macs now share the same Apple Silicon M1 processor; so, according to the FAQ answer above, there should no longer be a performance obstacle—iPad should now be more akin to the Windows tablet PC situation mentioned above. Storage, too, is no longer an issue: the highest-end M1 iPad configurations include terabytes of storage.
In fact, working with uncompressed data such as RAW images and video is one of the selling points Apple is emphasizing in its promotion of these new iPads, and companies such as Adobe have promised to deliver iPad versions of some of their pro creative apps.

¹ Here's a link to the archived version of the FAQ concurrent with this writing, and a link to current version.
Answer: This turned out to be WavePad - which allowed editing and sound effects.
Comment: Quoted from NCH.com's website, "Send WavePad Audio Editing Software
This program isn't currently available for iPad, but it is available for the following platforms:
WindowsMac OS XAndroidKindle"
So NOT AVAILABLE FOR IPAD. So any other bright ideas?
Comment: @PeterBrown GarageBand :-)


Does the theory of multiple dimensions disprove itself?

Question: This video suggests that a universe exists for each different possibility in the world. However, doesn't that mean that there must be a universe in which this theory has been disproved? Wouldn't that make this way of understanding different dimensions nonsensical?
Comment: Incidentally, having watched the video, it is not entirely clear that the video makes very much sense beyond the 5th dimension. This is not to say that there are necessarily no more than four dimensions; only that the video seems more intended to "wow" than to elucidate.
Answer: Each possibility, from what range of possibilities?
By the very nature of the notion of something which holds "in a world", it does not make obvious sense that something which holds of a world can be a property of the collection of all worlds. To make a (rough) analogy: it is not clear that if one country does not (politically speaking) formally recognise the existence of any other country, that this should mean anything about the existence of any other country.
The Many Worlds Hypothesis in quantum mechanics is that any possible measurable outcome of an experiment, is in principle realised in some parallel 'world'. The existence of parallel worlds is not, however, an outcome which may be experimentally tested by any convincing means that we know of. (If we could, the Many Worlds Hypothesis would be much less controversial — it would simply be accepted as true or false, at least with as much confidence as other testable assertions.)
Answer: No. There would be no valid disproof. We generally hold that it is not possible to validly disprove something which is true. So if there are ten dimensions, any proof which concludes that there are not ten dimensions has a flaw somewhere in it. This is very different from some universes not being able to prove that there are ten dimensions. In some universes, I can imagine that an a-Ten-Dimensionalist could say:

There is neither sufficient evidence, nor reason, to believe that there are ten dimensions.

Such a person need not assert that there aren't ten dimensions. Should he/she do that, he/she would be in error.
Answer: The [realist interpretation of the] many worlds hypothesis does not disprove itself, but its lack of verifiability and its ad hoc use in cosmology -- a way to solve a problem where it looks there would need to be a creation event should give us reasons to doubt the truth of this hypothesis.
Moreover, a question arises as to what the existence of an infinite number of universes would mean for the nature of existence in any of them.


Resigning right after coworker

Question: I work in a small department where it is just me and my coworker and our boss.  Both my coworker and I have issues with our boss and we have brought it to management's attention and have had meetings and try to work things out.  Nothing really ever changes though.  Needless to say my coworker and I have both been looking for positions elsewhere.  She just got offered an opportunity and will probably be resigning today.  I am also in the process of getting an opportunity and anticipate receiving an offer next week.  This is boss is fairly new and will probably be completely lost without either one of us.  I feel bad but I have to do what is best for me and my future.  Is There anyway to do this on good terms??
Comment: You have made mangement aware of your problems.  I assume nothing or very little changed in an reasonable amount of time.  If thats the case you should feel nothing leaving a company that does nothing to address serious personel problems.
Comment: You could negotiate with your boss a longer resignation notice.
Comment: Similar: http://workplace.stackexchange.com/questions/20357/a-coworker-beat-me-to-resignation-how-can-i-resign-in-a-professional-manner .
Comment: The fact that you feel bad means that you are a nice person. But this is business, and as you say, you have to do what is best for you. You can't stay in a job that isn't working for you just because it will make life difficult for your manager if you leave.
Answer:
Is There anyway to do this on good terms??

As they say "timing is everything".
Unfortunately, sometimes things just work out this way, and it might be tough on the company and your boss. That's not really your problem, although it's nice of you to be concerned.
When you give your resignation, just be as professional as you can be. When you talk with your boss, you might offer something like "I know the timing is rough, but it was just a coincidence..."
If it works out for both you and your new company, you could offer a bit longer notice period, as a way of easing the transition. You could also offer to help train contractor replacements during that period.
Of course, you'll offer to document everything you've been doing as an aid to future workers, if that will help.
It's unlikely to matter that all that much. Acting professionally and offering help is always your best bet as far as leaving on good terms.
Comment: You could also offer to do some moonlighting for the old company to help them through the transition (i.e. hourly contractor who works in the evenings and weekends).  This can be beneficial for both you and the company.
Answer: The only way you are leaving on good terms is by not leaving. But even if you choose not to leave, being on "good terms" with your boss is a very relative expression, given that your co-worker's and your own attempts at achieving some sort of co-existence with your boss have all so far ended in failure.
Given that leaving your boss on good terms is an outcome that won't happen, I suggest that you collect your references from your boss previous to your current boss and any current management that you have a good relationship with before you leave.
Your decision to leave is made. Keep any recriminations between you and your current boss to an absolute minimum, because - who knows, you might return to the company at some point in the future. And recriminations at this point are irrelevant anyway.
You need not concern yourself with what happens to your boss. She may survive your co-worker's and your departure - that's no skin off your nose because you are no longer working for her anyway, or she may not. If she doesn't, consider going for her job. Or recommending to one of your friends that they apply for her job. Your boss's survival in her position is out of your hands - if you still feel a twinge, give your hands a good washing :)
Answer: They will almost certainly offer you an incentive to stay. Work out now dispassionately exactly what it would take in terms of raise, promotion, responsibility or other changes.
If it's a simple matter of a pay rise then ask for it. Right now. Don't give any ultimatums, don't say what you will or won't do, don't explain the reason. Just ask for what you need to stay. You probably wont get it - that's fine. Just resign when your job offer arrives. Now it's pointless them asking 'Is there anything we can do?' - you already asked, they said no.
Answer: I completely understand the conflict you have here; even given the troubles with your boss, you undoubtedly have some personal connection to the company and to the work, and don't want to see it fall apart.
If you're not able to negotiate a longer resignation period (or don't want to), and if your new company permits and it doesn't create a conflict of interest, you could consider offering to do some consulting to train whomever they find to replace you - come on on a Saturday, something that wouldn't interfere with your present position but would both make it easier on your current company and make you some extra money on the side.    Alternately, you could also offer to do a small amount of project work on the side until they find someone and bring them up to speed, again assuming it doesn't create a conflict of interest.
Either way, be very careful in offering this - both in ensuring that it won't cause a conflict of interest at your new position, and in ensuring your boss understands the limits of the consultancy, in terms of time and in terms of scope.  You may not want to offer it right away, as you will not fully understand the culture of the new company you're working for.
Answer: It's admirable that you're thinking of the welfare of your company and I can see how you would be wary of it impacting on your future career prospects but I believe you're actually in a strong position.
The biggest concern is in future recommendations.  Most companies will be looking for confirmation that you did work for company X, that you were in position Y when you left and that you weren't sacked.  Beyond that, the reference isn't all that important.
With that in mind, you need to think about what you want to do.  Do you actually -want- to leave, or would you be happy to stay if things changed?
If the latter, it might be worth trying to rectify the situation.  Your boss will (prbably) not want you to leave as it'll leave them short of resource and experience, plus look awfully bad on -their- record.
Go to them and lay your cards on the table.  The best, and most professional, approach is to say "Our work relationship isn't good and it's got to the point where I'm looking to leave.  We need to work out a compromise solution or I'm handing in my notice."
Give your boss time to handle this as some people, especially those who're lacking in experience and/or confidence, find it difficult to admit that they've made a mistake.
Whilst it's common practice for bosses to define what they expect from their employees, it's equally valid for employees to have requirements, too.
Bear in mind that the worst that can happen is that you change job.  In today's climate, you should be expecting to change job occasionally, anyway.  It's not always a pleasant experience but it's the way things are today.
You have power in this situation, don't be afraid to use it.

Resigning right after coworker


Does setting the max memory of a Java program affect the GC?

Question: Does adding -Xmx argument when running a Java program cause the garbage collector to act differently or occur less often?
Answer: Yes, most Java garbage collectors only run as needed, as opposed to running on a schedule whether needed or not. So, in general, more memory causes less frequent, longer garbage collections.
The generational garbage collectors have settings to control the allocation of memory between the young and tenured generations. By setting these to use a smaller proportion of total memory for the young generation, the absolute size of the young generation can be kept the same as the total heap size is increased. Then, you won't see much of a change in garbage collection frequency or duration—but you will have more room for long-lived objects for applications like caching.
Answer: The general answer is that garbage will tend to be collected less often but the GC pauses will tend to be longer.
This is assuming you already have more memory available to the VM than your working set size; otherwise you might be spending a lot of time in garbage collection.
The GC characteristics vary greatly depending on which collector you are using and which version of Java, and whether you specified a higher -Xms in addition to the higher -Xmx. Older versions of Java (before 5) did not resize the young generation space after the VM had initialized. So even if you specified a really large -Xmx value, the size of the young generation would still be really small so you would see frequent young generation collections.
When a young generation collection occurs, there will be some "young" objects that will be promoted to the tenured space anyway, even though they are short-lived objects. This means that the tenured generation will slowly fill up with dead young objects, requiring periodic full GCs. The number of such objects that end up in the tenured generation is proportional to the number of young GCs (assuming constant activity in your program). So the advantage of a larger young generation is that there will be fewer young generation GCs, and therefore fewer objects from the young collection will be promoted to the tenured generation.
There are a number of tuning parameters besides -Xmx (google for java gc), and you will have to experiment with them since the optimal settings will vary for each application.
Answer: Yes, but it depends on which garbage collector you're using. The GC tuning page is a good resource for this sort of question.
Answer: It does, because when you have more memory then when it comes to collect and compact it has more to scan. This means that when a (full) GC does kick in that means that it will have to scan more memory, and potentially compact more memory too.  Perhaps with more context we can help further. There are obviously three different sections that get scanned, so it doesn't necessarily correlate directly in a 1-1 sense.
Answer: Only indirectly, and after running for a while.  -Xmx sets the MAXIMUM size the heap is allowed to grow to, and doesn't affect the initial size.  So it won't affect gc time or frequency early in your program's run.  If the heap is still (too close to) full after a gc, the heapsize will be increased, and this is what -Xmx will affect.  A higher setting for -Xmx will allow the heap to (eventually) grow larger and thus trigger collections less often (and those collections will take longer, as others have described).
If, however, your application doesn't use too much memory (so the heap is mostly empty after a gc), the heap will never grow, and the -Mx setting will be irrelevant.
You can use -Xms to set the initial GC heap size.  This will have an immediate effect on garbage collections.


How do the hydraulics in an airplane have constant pressures? What is creating resistance to the pump flow to create constant pressure?

Question: my question comes from the A320 specifically, and I also suppose Boeing jets. Whenever you check the hydraulic system pressures on an A320 it says 3,000 psi, even when you move the flight controls. How is this pressure a constant 3,000 psi no matter what? What is creating the resistance to create this pressure? Thank you very much!
Answer: The hydraulic system contains a pressure regulator device which maintains almost the same source pressure to the cylinders across the full range of flow rate demands, regardless of what the pressure being developed by the pump might be.
In practice this would mean designing the pump to develop a minimum of, say, 3100 PSI across all engine speeds and then putting in a pressure bypass that automatically flows the extra 100 PSI back to the pump sump.
When the flow demand on the hydraulic system is high, the pressure bypass progressively closes so as to maintain 3000 PSI throughout the system.
Another way to do this is to control the pump motor with a pressure sensor that automatically cycles the pump motor anytime the system pressure falls below 3000 PSI. What you will hear in times of high hydraulic system demand is a surprisingly loud VOOOOT! VOOOOT! VOOOOT! noise as the pump cycles on and off to hold the source at 3000 +/- (some value) PSI, which I have indeed experienced on the 320 upon landing (when the flaps, spoilers and whatnot are all being retracted).


Can a business allow employees to use their own developed software for work as a way to protect its proprietary software?

Question: Can a business allow employees to use their own software for work as a way to make sure that if the company has to declare bankruptcy and sell all its assets, then it can hide its proprietary software from liquidation? I was thinking of how a company would try to protect its method of making money from being forced to given up if there was a bankruptcy or the courts were trying to seize property and the only way I could think of is if it wasn't owned by the business in the first place. But I don't know if there is a law restricting employees using their own software like that for this very reason. Is this possible?
Comment: Is this proprietary software or commercial software?
Comment: Proprietary software either given to the employee or directly created by the employee to do their job while still being owned only by the employee.
Answer: Yes, companies can protect assets from creditors
The ideal corporate structure for a small private business is:

An operating company that deals with customers and outsources everything to:
A labour-hire company that employs all the staff, and
A purchasing company that deals with supplies, and
A holding company that owns all the assets.

That way, if anything goes wrong in any of the companies it can be wound up and a new one spun up to replace it.
There are variations on the theme: construction businesses may spin up a new company for each project, mining companies a new one for each mine, property companies a new one for each property holding (usually as a trust) etc.
Providing the contracts between the companies are genuine commercial arrangements and the directors act in the best interests of each of the companies, this is generally legal.
Comment: @user253751 nothing but costs. Each of these structures cost money to set up, lawyer fees, filing fees, taxes, and usually demand their own tax return forms. You can put one asset in each company if it makes sense when the asset value is big enough (i.e. with real estate).
Comment: Why not go even further: why not put every individual asset in its own company?


What do you call the state of being after orgasm that makes it impossible to continue?

Question: I was thinking of "sexual exhaustion", but it's not "sexual exhaustion" since you are not feeling exhausted after orgasm. Your sexual organs just get really sensitive. Is there a word or a term for this? I know it's a weird question, but to this day I have no idea if it has a word or a term.
Answer: Although not a commonly used term, it's called the "refractory period",.

In human sexuality, the refractory period is usually the recovery phase after orgasm during which it is physiologically impossible for a man to have additional orgasms. This phase begins immediately after ejaculation and lasts until the excitement phase of the human sexual response cycle begins anew with low level response. Although it is generally reported that women do not experience a refractory period and can thus experience an additional orgasm (or multiple orgasms) soon after the first one, some sources state that both men and women experience a refractory period because women may also experience a moment after orgasm in which further sexual stimulation does not produce excitement.
Comment: Oh right! OP means "unable to continue *having sex!*" I thought we were talking about not having the energy to go and find a lighter so you can have a post-coital cigarette!


Why using Autoencoder in nlp seem hard to do?

Question: I want to implement an autoencoder with theano to express each article. When I made it following the tutorial of UFLDL. I found that it's hard to get gradient descent(I use LBFGS). I want to know whether it is due to the sparsity of the BOW input?
Answer: Typically people train autoencoders on the sentence level and not for entire articles. That may be why you are having trouble training your model.


Searching flights - how to exclude certain layover countries?

Question: Is there any flight search website that allows to exclude results with layovers in certain countries?
Comment: Does this answer your question? [Searches that exclude particular transit airports](https://travel.stackexchange.com/questions/152294/searches-that-exclude-particular-transit-airports)
Comment: As a gentle reminder, one of the expectations of Stack Exchange is that you demonstrate your attempts at initial research. For example, which websites have you checked already? This saves the answerers from having to spend time on duplicated effort.
Comment: @Kate Gregory it doesn't, because the question is about countries rather than airports.
Answer: In ITA Matrix there is an advanced routing code for filtering entire countries. Just enter <code>~l:nUS+</code> in the routing codes section to avoid layovers in USA for example.
This is where you enter the routing code.

These are the results without any routing code.

These are the results when specifying no layovers in USA.
Comment: That's great. Thanks. How do I exclude several countries?
Comment: It seems like the following code would exclude both USA and Canada. ~l:nCA,nUS*
Answer: The only site I know with remotely close functionality is ITA Matrix (http://matrix.itasoftware.com). There, you can use "Advanced routing codes" to specify certain airports (though not countries) to not transit through.
Let's say you're going from San Francisco to Delhi, but for whatever reason, would like to avoid China, Japan, and Korea. Off the top of my head, I know that the major hubs in China, Japan, and Korea are ICN (Seoul Incheon), NRT (Tokyo Narita), PEK (Beijing), PVG (Shanghai), HKG (Hong Kong). We can use advanced routing codes to exclude these:

The results predictably go through Europe rather than Asia (e.g., through Munich, Istanbul):

If you missed any airports the first go-around, you can go back and add them to the search filters. Once you have a result that you'd like to book, copy and paste it into BookWithMatrix to book the ITA Matrix itinerary.
Answer: Google flights gives you a list of transfer airports it has found and lets you include/exclude them from your search.
Unfortuately it doesn't tell you what countries those airports are in or offer a quick way to (de)-select all the airports in a given country. So excluding all the options in a country like the US may take a fair bit of effort.
Answer: I don't know about excluding particular layover countries.  However, some sites will let you pick only certain airlines.  I believe these option will let you filter out some countries.
For example, a flight search on https://www.travelocity.com/ will let you do the basic search (from, to, and dates) and then let you restrict the search to specific airlines; whether the routing is direct, 1 stop or 2+ stops; and whether the depart/arrive times are morning, afternoon or evening.
Similar options are available with https://www.kayak.co.uk, https://www.expedia.com and probably elsewhere as well.


What would I search for to find bike hubs that attach on only one side like found on tadpole recumbent

Question: What is the name of the hubs used on recumbent tadpole trikes. Those tricycles that have two front wheels and a conventional rear wheel
Comment: Their web site states "2 ea. Wheel Chair Hubs, with .5" axles"
Comment: @NateWengert this is a perfectly good answer, it should not be a comment.
Comment: Possibly a dupe of https://bicycles.stackexchange.com/questions/46329/ but that's more about trailer wheels.  You'll need something with brakes as well.
Answer: They are often referred to as just that, a tadpole trike hub assuming you're looking for the front hub. They differ from standard trike hubs slightly. If you are in the united states or Canada you can get on of these from a shop. Let me know what country you are in as you are unregistered and I will do my best to answer.
http://www.jbi.bike/web/checking_product_description.php?part_number=38751
Comment: It's a 36 hole, 6 bolt disc hub. The 36H in the description is the hole count, and the large flange on the right side is for the 6 bolt disc brake.
Comment: I am in California The link looks like it goes to a tadpole front hub But it has no axle and I can not tell if it is disc brake compatible or what is going on on the side. The link also gives no specs i.e. axle dimensions or number of spoke holes
Comment: Axle : http://www.jbi.bike/web/checking_product_description.php?part_number=38883
Answer: Some DIYers repurpose pedal axles, e.g. starting at around 3:24 / 11:26 of Tinny's busy day - YouTube
Some pedals use the same bearings as front hubs; main challenges will be:
- threading/securing pedal axles into tadpole uprights.
- sorting pedals and hubs with compatible bearings and widths
- disassembling pedal and hub assemblies
- reassembly, replacing hub axles with pedal axles.
Comment: That's a really interesting thought.  Could you please summarise the main advantages and disadvantages, and give a brief outline of their process?  If the linked website ever goes away then this answer can stand alone.   Okay,  youtube's unlikely to vanish, but the video can be deleted, or it might someday go behind a paywall, any of which would rend this question into a kind-of dead-end.   Welcome to StackExchange!


What's the best way to deal with off-topic comments

Question: Unlike some other SE sites, I've noticed (and sometimes contributed to) a good deal of discussion in the comments here at skeptics. Sometimes these back-and-forth comments are about problems with an answer, clarifying question or suggestions for improvement, which seems to be appropriate for a comment, as per the description of the comment privilege. Sometimes they involve clarification of a downvote reason, which also seems to be appropriate, though not explicitly addressed in the description of the privilege.  Often, though, they don't seem to fit any of these categories.
Since I'm trying to become a good Skeptics.SE contributor, what is the best course of action, here? In my answer to this question, the OP uses comments to try to discuss an element of the original question that was edited out in order to keep it on-topic for skeptics. The original question included references to a non-notable claim about the political ramifications of a drug that was also used for abortions having another use, and mentioned that the author of some of those studies was someone who accused a US Supreme Court nominee of sexual assault. These two facts don't have much to do with the notable claim, that the drug is an effective treatment for a specific condition, but they might make it seem more topical and interesting to users scanning question titles. You can see the history of the question and the response to it in the comments to the OP and the question's revision history.
My instinct is to respond to the comments. In the comments to my answer, I've tried to be clear that I don't think they are on topic, but that doesn't seem to be working. I'm reluctant to flag a comment for not fitting the guidelines for commenting, since they're not harassment, unkind, or obsolete, but I also don't like the idea of letting the comments suggest that there is something missing in the answer, or that the author's speculation is a significant issue. I ended up responding to the issue itself (though I probably shouldn't have) when it was raised in comments on this answer.
What's the best course of action here? Leave it alone? Flag it? Keep responding that it doesn't relate to the question (despite being the OPs question)? Am I misunderstanding the role of comments on skeptics.SE? I can see how it might be important to give the author of a question a little more leeway in comments on answers to his/her question, since the are, after all, the one who asked it. At the same time, if that part of the question doesn't meet the criteria for a question here, the comments could be seen as a way to get around those criteria.
Comment: I've cleaned up the comments. I think flagging is fine, we'll be happy to keep an eye on stuff like this.
Comment: @Sklivvz see comments on [this answer](https://skeptics.stackexchange.com/a/42415/46182) for the same user's similar attempts to discuss the same off topic issue.
Answer: I favor that comments that add to the ideas in the post remain, then are pushed to and preserved in chat if there's many of them, but that rabbit trail comments should be avoided, then flagged and deleted. The moderators here delete comments a little more heavily than I would. It's perhaps too heavy sometimes, but usually fine.
Bottom line: comments that clearly add needed information should just be added to the post, while other info that walks the line should be commented and may be deleted.
A lot of a proper skeptic attitude is thinking out loud. Comments are a good place for this, but once answers have the good and correct ideas, those comments should be deleted, and they usually are.


How to log-in via TTY by instead of GDM?

Question: I want my Ubuntu box to boot directly into a tty login screen and after it does that I want it to automatically run startx how would I go about doing this?
Comment: I don't mean to be nosy, but why do this? If you want to end up in a graphic environment by default, why not use a display manager?
Comment: to deter thiefs
Comment: I doubt that thieves will be interested in the contents of your computer, and if they are i'm sure the can find out hot boot from a live-cd. If you fear for you data's security encrypt you disk.
Comment: its not my data I'm worried about its the physical computer if it boots into a text based environment they'll assume its broken and not take it (or so I'm hoping)
Comment: I doubt a thief will even touch the power button
Answer: What txwikinger said, but then to make it automatically run startx when you login, edit ~/.bash_profile  -- that file is only executed on login shells, not in normal terminal emulators that you open on your desktop.
EDIT:
~/.profile if you don't use bash
Answer: You can disable the automatic start of the X-server by disabling the start on lines in gdm.conf and/or kdm.conf. This way upstart will not automatically start the X-server.
After logging in into the tty, you can just start the appropriate login session via sudo start gdm or sudo start kdm. Or if you rather want the traditional x, you could run startx, if it is configured such that you can do the things you want to do from that.
Answer: Turns out from the grub boot menu you can press e over any entry to edit its configuration.  If you do this over the ubuntu entry there is a line that starts with the word linux and ends with something like ttyhandoff=7.  Changing this to ttyhandoff=1 does what you would expect.
Apparently you could also append text to the end of this line.


sql injection for sessions

Question: I used mysql_real_escape_string() to prevent sql injection for the $field variable below. Should I use the same for $_SESSION['user_id']?
I can't imagine someone being able to change a value in the $_SESSION array. Can they?
$query = "SELECT `".mysql_real_escape_string($field)."` FROM `users` WHERE         `id`='".$_SESSION['user_id']."'";

Comment: As long as you believe your `$_SESSION['user_id']` is secure, you don't need to escape it (you have to look at your session handling code to make sure it's secure). It couldn't hurt to over-escape things though.
Comment: Instead of escaping (and concatenating, which is always problematic), which may require certain global settings be turned off, you should probably be using parameterized queries.  For one thing, it prevents future idiot developers from accidently concatenating un-escaped fields, or even having to go back and _add_ escaping to previously 'safe' fields that may suddenly have user data in them.
Comment: http://bobby-tables.com/php has examples on how to use parametrized queries.  Learn to use them.
Answer: They can't change the $_SESSION array, but your problem totally depends on how you initialized $_SESSION['id']. In a general way, you should always escape values in a SQL query. Don't try to guess whether or not values can be modified from an user input, just escape them.
Comment: I didn't want you to paste your code, it is not necessary :) Just escape every values, and everything will be fine.
Comment: Good idea - i'll escape the session in the query.

also here's the code for where I initialized the $_SESSION['user_id']:

   $query = "SELECT `id`, `email`, `password` FROM `users`
WHERE `email` = '" .mysql_real_escape_string($email). "' AND `password` = '" . mysql_real_escape_string($password_hash). "'";
if ($query_run = mysql_query($query))
{
$query_num_rows = mysql_num_rows($query_run);
if ($query_num_rows==1)
{
    echo 'You\'re logged in!';
    $user_id = mysql_result($query_run, 0, 'id');
    $_SESSION['user_id']=$user_id;
    header('Location: index.php');
}
Comment: i have no idea how to get the above code to look better. sorry dude.
Answer: Client can't change your SESSION values.
But I believe someone who got access to your server can. (But at that point you should worry about other things)
Answer: If your session variables are ever populated with user variables, then your session variables are just as vulnerable to SQL injection as any other user-manipulated variable. You may also do this in future and forget to go back and escape the SQL query.
It causes no harm to escape everything and leave that escaping until the very last moment (i.e. when the value is being passed to the query); this avoids any other manipulations of the variables negating the effect of the escaping.
Answer:
I used mysql_real_escape_string() to prevent sql injection

That's what you did wrong.
mysql_real_escape_string() does not prevent whatever injections by any means.
This function intended for string formatting and shouldn't be used for anything else.
To format an identifier you have to enclose it in backticks and escape the very backticks inside

sql injection for sessions


Why there is no option to delete sms in marketing cloud?

Question: why there is no option to delete sms in marketing cloud, whereas we can delete journeys, emailers, data extensions etc. on the other hand.
Answer: This is more of a product design question, though I agree it's not very userfriendly.
Anyway, you should always mark the SMS messages that are not in use / expired as Inactive in MobileConnect, as this way they will at least get removed from the view in 6 months time.
So while you cannot delete them manually, the documentation states the following:

After 180 days, MobileConnect archives inactive messages and removes
  them from view. You can still review information on archived messages
  in the calendar on the day the message was sent.

Deactivate SMS Message
Answer: You can delete the SMS message, which is in DRAFT status simply by selecting a different template. The popup will tell you that "changing the template will discard the draft". And eventually, the message will be deleted.


How can I hide the Text Format selector when there is only one?

Question: When a user has only a single text format option, just Filtered HTML for example, the selector is still shown even though there are no other options.
How can we remove this when there is only one option?
Answer: The form element type you're probably working with is a 'text_format' type.  This is a composite element/widget.  You can modify this form structure using hook_form_alter().  It's a bit hidden, but you can change 2 properties on the widget to control that dropdown.
Make sure you are editing the form structure of the widget, not any containers.  See the below code example for an idea on which element to update:
$form['description']['widget'][0]['#format'] = 'full_html';
$form['description']['widget'][0]['#allowed_formats'] = ['full_html'];

You can change 'full_html' to 'restricted_html' and see the editor change.  Whatever mode you wish to enforce, you can set the machine name there and it'll set that as the default + hide the dropdown.
See \Drupal\filter\Element\TextFormat.php for some more info (contained in the annotation at the top of the file):
/**
 * Provides a text format render element.
 *
 * Properties:
 * - #base_type: The form element #type to use for the 'value' element.
 *   'textarea' by default.
 * - #format: (optional) The text format ID to preselect. If omitted, the
 *   default format for the current user will be used.
 * - #allowed_formats: (optional) An array of text format IDs that are available
 *   for this element. If omitted, all text formats that the current user has
 *   access to will be allowed.
 *
 * Usage Example:
 * @code
 * $form['body'] = array(
 *   '#type' => 'text_format',
 *   '#title' => 'Body',
 *   '#format' => 'full_html',
 *   '#default_value' => '
The quick brown fox jumped over the lazy dog.
',
 * );
 * @endcode
 *
 * @see \Drupal\Core\Render\Element\Textarea
 *
 * @RenderElement("text_format")
 */

If you're unsure what the machine name for your text format is, you can find the list under Configuration > Content authoring > Text formats and editors.  The machine name of that format will be found in the URL as a named parameter.  The three default ones you get with Drupal are full_html, restricted_html, and basic_html.  Other modules may add text formats so you can find the full list there.


Should I define each and every term while writing an article for a psychology journal?

Question: I am writing a review article on dialectical behavioral therapy. If in the article, there are technical terms related to behavioral therapy, so, should I define each of the terms while writing the article or should I assume that the readers/editor/reviewers of the psychology journal know all these terms. For example: A term, cognitove behavioral therapy (CBT). Should I explain what is CBT or should I assume that readers know this type of term.
Comment: Welcome to psych.SE.  This may be more of an opinion-based question that wouldn't be a good fit for this forum.  I believe it's common practice to define terms that are important to the main content (like CBT), and for other terms (like conditioning), link to their definitions elsewhere.
Answer: This question may be better directed to academia.se.
In the first instance, you should check the editorial requirements of the journal you are targeting.  Most journals prescribe that it is mandatory to spell out acronyms with first usage.  It is possible that some very specific technical journals will allow common terminology through without being specific.
Your question is interesting in that you have used the acronym CAB for Cognitive Behavioural Therapy, for which I use the acronym CBT.  I personally associate CAB with Clinical Assessment of Behaviour.  Clearly the acronyms CAB and CBT are not as well established as I had understood.
Comment: @jai Have you read papers in the journal you are submitting to? If not, why not? and why would you submit to a journal you have not read from? If yes, why can you not use those papers you read as a guide for what is normal?
Comment: My question is not about spelling out the acronym. I want to ask that while writing an article, what type of reader should be kept in mind. The reader of journal or the reader of other field or both?  If I am considering the reader of thag target journal, I may not have to expalain about every term that I may expect from the reader of that journal that they know about the term.


How to make apache open files that have only owner execute permission for all users?

Question: I have installed LAMP on my Ubuntu Server while being user (say "test"). Then i switched to another user (say "user") and I have configured a virtual host. The virtual host directory at www/ has 744 permissions. When I try to reach the virtual host from the browser it says "You don't have permission to access / on this server.". When I changed the permission to the virtual host directory at www/ and made it 745 the host could be reached from browser. I suspect that this is because I installed apache as user "test". How can I change it so that it can open files that have -x permission only for owner while being logged in as the owner user?
Comment: Give it a permission of `775` rather than `745`
Comment: Actually I want to do it without changing the permission 744.
Answer: 744 is not normal for directories. I would believe it should be 7[750][50], and 6[640][40] for files. Where I prefer "0"/"0" for "others" and "5"/"4" for groups.
For 745 I doubt there is a valid usecase: permissions really should trickle down from user to group to "others" so the user has the most permissions and others should have the least.

How can I change it so that it can open files that have -x permission only for owner while being logged in as the owner user?

Add the user to the group that owns the directories and files and set permissions to 750.
Change the owner of those directories and files from "test" to the user.
chown -R $USER /var/www/

(assuming /var/www/ is your root; adjust accordingly) would do that. By the way: if you only want user to execute you should use 700 and 600 or set the group to the name of the user and empty out the group from any other user.


Underwater City- Applications of Nanotech

Question: With the rise of global warming and our leaders not seeming to do enough about it, expanding our ranges past the earth's ground seems like something we must do eventually. Everyone always points to the sky, but the earth has much more room than what is just dry land. In this scenario, we instead build to the seas. The easiest way would be to build around the cities we currently have to keep the water out. My question is how would you do this? If the water becomes too high large walls might not be enough. Are there any new nanotechnologies that could build a dome that would allow sunlight through but also strong enough to keep the water out?
Comment: Maintaining an underwater domed city sounds like a nightmare. You'd be wanting to some exceptional nanotech defenses against [biofouling](https://en.wikipedia.org/wiki/Biofouling), that's for sure. I'd rather just grow some new islands if I had that kind of wealth, power and fancy technology.
Comment: "The easiest way would be to build" **inland**. There is not enough water on Earth to raise the sea level more than about 70 meters. Even at maximum sea level only a small part of the land would be submerged. During historical times many cities were lost to the sea, and many former seaports found themselves far from the shores. People moved and built new cities.
Answer: Simple quick basic answer is we already have that tech now.
Note other architectural suppliers are available https://www.britesolar.com/ It is relatively easy to build transparent solar glazed domes that can have liquid glass to shield from marine environments.
For an example of an underwater restaurant see https://en.wikipedia.org/wiki/Underwater_habitat#Ithaa_undersea_restaurant
By Alexey Potov - Noblige - Taken by Alexey Potov - Noblige, CC BY-SA 2.5
And for villas see https://edition.cnn.com/style/article/floating-underwater-villas/index.html
If you wish you can book your underwater stay at https://www.booking.com/articles/5-unforgettable-underwater-hotels.html or place a
Poseidon resorts reservation :-) at http://www.poseidonresorts.com/overview.html#sliderReserve
The main question has to be why since historically when water encroaches we naturally move to higher ground. One scenario is that the cost of higher ground becomes more than the cost of spreading into the sea. thus it is highly likely in the future. Currently the value of protecting a costal city is unlikely to bear the prohibitive costs.
Most historic and present applications are based on research or tourism where the purse may be available for esoteric projects.
What form could it evolve through? It is possible in a country rich enough to allow individuals to build/rent  personal pods that a coastal village with interconnecting links/hypertubes could easily be compartmentalised in the event of local failure but the need for redundancy would suggest an outer segmented transport hub rather than the star shaped schemes often proposed.
Comment: Very good, particularly liked the last paragraph +1
Answer: Since I'm assuming said dome is going to be pressurized with breathable atmosphere, the key factor is depth. For every foot of salt water (fsw) you are adding .445 psi of pressure per square inch of surface area. That equates to +1 standard atmosphere (14 psi) every 33 feet of depth. At shallow depths, say < 100 feet this should not be much of a problem. Safety glass might could be an option (albiet a very heavy one) or even something lighter like acrylic. You could also pretty easily snorkel in oxygen, power cables, communication cables, etc.. from the surface at that depth, possibly even have some service tunnels for people and supplies - even evacuate if needed.
But at greater depths once you leave the area of the continental shelves and are in open ocean (say 300 meters though there are certainly much deeper areas) you are under tremendous pressure, approaching the hull crush depth of most Submarines - and those are solid steel monohulls with no windows. You can buy a little more depth if you increase the pressure of your atmosphere but people have to acclimate to it at a controlled rate. The chances of safely evacuating from that depth are remote. There is little light and little life, it would be a very challenging place to survive. I've operated robots at that depth (and deeper) but I would be very worried to personally be in anything man-made at that depth.
But building it is only the first challenge - subsea engineering is hard. Your life relies on how well your machinery is working. If there's an oxygen-plant in the dome, oxygen is an accelerant - a tremendous fire hazard. Liquid oxygen is compressed at a ratio of 742:1, even if there's no ignition source the force of even 10 liters of LOX expanding to room temperature would probably be enough to damage that dome. For a crew of say 100 you're probably looking at more like a 1,000 liter LOX plant. If that blew it would be more than enough to shatter the whole dome. Best to keep it like a mile away from the dome and connected by hoses - and if there's a problem then send a robot to fix it.
Electrical power is another concern - you can't lose it. Period. If there's an electrical fire and it disables the power distribution, now you're down to battery backup power and emergency lights - that may be game over if you were trying to bail out a leak then you can't power your bilge pumps anymore. The water wants to get in, the machinery breaks down, it would be a tough way to live and you would need support from the surface. Put everyone in one big dome and a single point of failure can kill everyone. But have a lot of domes connected with service tunnels and at least you can seal off an area with watertight doors if you're in an emergency.
Hope that helps and I'm happy to share more if you want


Which method does pyQuil use to compile a Program?

Question: I want to find out which method different compilers use to decompose a matrix into smaller gates. I went through the pyQuil code on github but could not find the answer there. Maybe i lost track of something. I would by highly interested in the methods used by PyQuil.
Answer: Pyquil uses QuilC to compile programs to native gates: https://github.com/quil-lang/quilc


Is it possible to add a simple image or graphic to the map canvas?

Question: Is it possible to add a simple image or graphic to the map canvas in QGIS (e.g. a symbol marker)?
Comment: what QGIS version are you using?
Answer: You can add a symbol to the map rather than the print output in Composer.
QGIS 1.8.0 Lisboa has some generic symbols included. If you go to Settings/Style Manager then ADD then Symbol Layer Type and choose SVG Marker you can choose from a number of symbols there and save the one you want.
Once you have your chosen symbol you need to add a Shapefile Layer in Layer/New and choose New Shapefile Layer.  Give the layer the attributes you require, ensure it is POINT type rather than Polygon, and save. The new layer will appear in the Layers area. To add your new symbol ensure you are working in the new layer. Toggle editing on and choose the Add Feature tool. Click in the position you want your new symbol and you will get a small round generic point symbol.
To get your chosen symbol you need to right click the layer, choose Properties and then the Style Tab.  The symbol you chose earlier should be there ready for you to choose.
Comment: Thanks.  SO I do have to make a shapefile to add a dot or line to a map. At least that is easy to do.
Comment: You don't HAVE to Allison but safest to so you don't start editing and possibly getting in to trouble with your original data.
Comment: If a given answer works for you Allison it is worth marking it as the accepted answer. It helps your reputation and shows others with a similar problem that the answer is a good one.
Answer: Assuming that you are using at least QGIS Wroclaw (1.7.4), images or graphic in can be added in composer:
<code>File -> New Print Composer -> Layout
</code>
and you will find all the options you are looking for.
Comment: I was wanting to add something to the map canvas, so it moves with the map. But thanks anyway. (using latest version - just downloaded and learning QGIS)