Pomagranate mead sour

Question: I've been working on a pomagranate mead that has been fermenting for 3 weeks. I just racked it for the first time today and I tried a some, it was super sour... anyone know if this is normal and if it will go away and have the original pomagranate taste back. Also what might of caused this, did my pomagranate mead go bad or something
Comment: Can you describe the recipe and the process you followed?
Comment: Yeah I used 16 oz of pomagranate juice, 2 lbs honey,2/3 tsp Acid Blend,  yeast nutrient, 1/3 tsp Pectic Enzyme, 1/3 tsp Grape Tannin, and 1 campden tablet for first racking, cote de Blanc Wine Yeast... you boil honey at 180 for 10 min, let cool and add everything else.. rack after 3 weeks
Answer: I can think of two reasons why your mead is sour:

Pomegranate juice is sour, with a pH of around 3.0. Assuming you've made 1 gallon batch, 16oz of pomegranate juice is enough to be noticeably tart. 16 oz of a pH 3.0 liquid diluted to 1 gallon yields a pH of around 3.9 which, without any sugar to balance the acid, would taste quite sour.
Your mead was infected by acetobacter while fermenting. There's a group of bacteria called acetobacter that produce acid. They are responsible for sour pickles, sauerkraut, and vinegar. If this is the case, your mead would have a vinegar smell and taste.

My bet is that you don't have an infection; it's just the natural sourness of the pomegranate juice.
Comment: Alright is there anyway to reverse this, just as sugar?
Comment: If you add sugar, it will just ferment. Check this site for advice on back-sweetening cider. Most of those posts apply to your situation as well. The simplest thing to do is make syrup from water and honey. Add a bit of the syrup to a glass of mead.
Comment: You can cold stabilize and some of the tartness can drop out in the form of crystalline precipitation.

Pomagranate mead sour


On the importance of an "honours degree" for PhD applications

Question: I am currently studying in an undergrad programme in the social sciences/humanities in North America, and I am debating whether I should pursue the honours degree option (which would require me to take additional coursework, choose a concentration, as well as write and present a honours essay).
I want to apply to grad schools (MA programmes, but I want to try to apply directly to PhDs as well) when I finish my BA, so I'm wondering what is the impact of the "honours degree" in the application process? Will this improve (significantly?) my chances of receiving an offer?
The main reasons why I'm hesitant about the honours degree are (1) that it would cost me more money and (2) that since I've already graduated from a different programme (in a different discipline) this is my second BA and time is starting to be an issue.
Comment: @Rüdiger - Can you provide any context for that statement? If so, please put it in an answer instead of a comment... that's what the OP is looking for.
Comment: Since I'm not an expert in the social sciences and humanities, I won't answer, but I'm very skeptical that that specifically matters; the system for determining things varies so much from school to school that you can't possibly expect graduate committees to know what it means at your institution.  In fact "graduating with honors" is so vague, one can't really answer the question without more info.  The only possible exception I can think of is if graduating with honors is so impressive at your school that it impresses your letter writers, and they explain this point.
Comment: Better with honors instead of no honors. simple
Comment: There are universities where having a BX (Hons) alone is insufficient for direct entry to PhD - you'd also need a perfect GPA from a credible institution, and preferably an MX. There are also universities where MX is a half-ass PhD and the programmes are identical except for the title of the degree awarded. You need to check sulabus, requirements and contact the universities you would apply to; we can't do that for you.
Comment: @Nij What is an MX? Never heard of it before
Comment: X an unknown variable, in the set of specialty fields.
Answer: Serving on a doctoral faculty for many years, typically when candidates are evaluated there are specific criteria that first have to be met. So, they will evaluate basic things like your GRE score, GPA, TOEFL score (if applicable). They will also evaluate your writing sample, if required to make sure that you will be able to write at the graduate level (use of references, clarity of writing, etc.).
Other than that, they will evaluate how well you fit with their program. Are you planning to study a topic that is aligned with the work already being done? Do they have an appropriate mentor/advisor to match you with? Do you express a sincere interest in research (our program emphasized research, but we would receive applicants who wanted a PhD and continue working as practitioners in the community. We weeded some of them out if it looked like they would not excel at research).
So, the Honors designation alone won't necessarily put you ahead of other candidates. That being said, if a doctoral program has a limited number of graduate stipends available, they may only accept the most qualified candidates - if the honors program you mention has specific coursework that is in strong alignment with the graduate programs you plan to apply to, then you may want to consider the additional study. However, if you have a strong record of the programs' requirements and write a compelling statement or writing sample, the honors program may not be your best investment. Best of luck!!!!!!
Answer: I think the value of an honors degree is much more in the activities required for the "honors" designation rather than the designation itself.
For example, at my undergraduate institution for my field, it was a requirement for honors to write an undergraduate thesis based on research in a lab, and to complete several seminar courses: your institution sounds like it uses similar specifications. Because "honors" means so many different things to different institutions, it is unlikely that a given PhD program will know what your "honors" designation really means; however, they can evaluate your readiness for a PhD based on the work you have done in courses and undergraduate research.


CiviCRM Spark fees, database migration/export and cancellation

Question: I need to cancel my monhtly fee as we have transfered to our server.
Can you tell me how to do this please.
I have tried to log in but says I have worng info to log in.
Also would like to know f the 18.48 monthly fee includes HST or not
Answer: You can export your CiviCRM Spark database by going to Administer > Backups. This should be sufficient to get started on your own instance, but you may need to also download CiviCRM extensions (CiviCRM will display errors on the admin pages telling you which extensions are missing, most of which are not critical).
The monthly fees do not have any HST, since the service is run from the United-States (assuming that by HST you mean Canada's taxes?).
Once you are ready to cancel, there are links in the monthly renewal emails to allow self-serve cancellation.
Please do not hesitate to contact us at email@example.com for any billing or cancellation questions.


Number of people online

Question: Is there a way to see the number of people currently logged in? If not is this something we should add?
Comment: I don't see how this feature can be useful. Math.SE is not a social networking site, after all.
Answer: This information is not displayed, nor should it be. The mere fact that phpBB shows it is a reason enough. Too many people mistake SE sites for forums; the  interface should not   reinforce this misconception.
When you write  a question or an answer,  assume that nobody is online now, and will not be until you step away from your computer. Make sure that it is clear and unambiguous   without any extra commentary from you.
Answer: Math.SE is not a social networking site, so there is no need for the "typical" user to need to see this information.  I do think it would be useful for moderators/site leaders to know, so we can get a feel for what hours may need the most moderation, etc.
However, there is one place on Stack Exchange that supports a "who is online" feature: the chatroom.  That section of the site is a border-line social network, but is also good for pointed questions to specific users.  A limitation, though, is that it only shows people who are in the chatroom.
tl;dr: "Who's online" isn't needed for the functioning of the main site; but, if you really want it, there's a similar (albeit limited) feature in the chatroom.

Number of people online


GnuCash Conversion from Quicken

Question: I successfully downloaded GnuCash and linked it with my Quicken data files.  But now all my account information is scrambled--bank balances up or down by an order of magnitude, securities sold long ago now showing up, and "categories" mixed up with "accounts."  GnuCash states that opening balances are "noneditable" so I'm stuck at the moment.  What's the solution?  Should I reinstall, set everything at zero and start over, or is there a simpler way to match this up with our previous Quicken entries.
Comment: Where are you reading that 'opening balances are noneditable'?  That doesn't match what I've read/done with the software.
Answer: While this is more of a software question and will probably be closed, I would say that yes you probably need to start again fresh.  You won't need to reinstall the software, just create a new account book and import the data again.  However, before you do this the second time, take a moment to read up on the process.  See if there was something that was incorrect during your first attempt.  There are many good quality guides online, along with the core documentation.  Review some of those and make sure you're checking the right boxes when you do the import.

GnuCash Conversion from Quicken


List of installed fonts OS X / C

Question: I'm trying to programatically get a list of installed fonts in C or Python. I need to be able to do this on OS X, does anyone know how?
Answer: Python with PyObjC installed (which is the case for Mac OS X 10.5+, so this code will work without having to install anything):
import Cocoa
manager = Cocoa.NSFontManager.sharedFontManager()
font_families = list(manager.availableFontFamilies())

(based on htw's answer)
Answer: Why not use the Terminal?
System Fonts:
ls -R /System/Library/Fonts | grep ttf

User Fonts:
ls -R ~/Library/Fonts | grep ttf

Mac OS X Default fonts:
ls -R /Library/Fonts | grep ttf

If you need to run it inside your C program:
void main()
{
    printf("System fonts: ");
    execl("/bin/ls","ls -R /System/Library/Fonts | grep ttf", "-l",0);
    printf("Mac OS X Default fonts: ");
    execl("/bin/ls","ls -R /Library/Fonts | grep ttf", "-l",0);
    printf("User fonts: ");
    execl("/bin/ls","ls -R ~/Library/Fonts | grep ttf", "-l",0);
}

Comment: There are also OpenType fonts (otf) in addition to TrueType (ttf).
Comment: That's not the only place you can find fonts: there's also `/System/Library/Fonts` and `~/Library/Fonts`...
Comment: Also, this doesn't factor that some fonts might be installed but disabled, and thus not available to the system. Using FontManager gives you fonts that are available, i.e. enabled.
Answer: Not exactly C, but in Objective-C, you can easily get a list of installed fonts via the Cocoa framework:
// This returns an array of NSStrings that gives you each font installed on the system
NSArray *fonts = [[NSFontManager sharedFontManager] availableFontFamilies];

// Does the same as the above, but includes each available font style (e.g. you get
// Verdana, "Verdana-Bold", "Verdana-BoldItalic", and "Verdana-Italic" for Verdana).
NSArray *fonts = [[NSFontManager sharedFontManager] availableFonts];

You can access the Cocoa framework from Python via PyObjC, if you want.
In C, I think you can do something similar in Carbon with the ATSUI library, although I'm not entirely sure how to do this, since I haven't worked with fonts in Carbon before. Nevertheless, from browsing the ATSUI docs, I'd recommend looking into the ATSUGetFontIDs and the ATSUGetIndFontName functions. Here's a link to the ATSUI documentation for more information.
Comment: ATSUI was removed in OSX 10.15.
Answer: Do you want to write a program to do it, or do you want to use a program to do it?  There are many programs that list fonts, xlsfonts comes to mind.
Comment: He said *programmatically*, so I assume he wants to write a program to do it.
Answer: You can get an array of available fonts using Objective-C and Cocoa. The method you are looking for is NSFontManager's availableFonts.
I don't believe there is a standard way to determine what the system fonts are using pure C. However, you can freely mix C and Objective-C, so it really shouldn't be to hard to use this method to do what you'd like.

List of installed fonts OS X / C


What does the term LPDO (Loose Pieces Drop Off) mean?

Question: I have been hearing the term LPDO (Loose Pieces Drop Off) a lot lately, which apparently is helping players in the beginning level. If so, does it prescribe some best practices and tips to help beginners?
Answer: LPDO (Loose Pieces Drop Off) is a reminder that unprotected pieces are vulnerable to tactics like forks. If two unprotected pieces (or pawns) are attacked at the same time then you can only move / protect one of them. One of your loose pieces is going to drop off.
In general this is used to guide weaker players to try and build up their position prophylactically so that pieces as much as possible protect each other. Stronger players, of course, can also come unstuck which is why you also hear this phrase occasionally made by commentators on GM games.
Answer: Excellent advice here from Brian and Hauke.  Another important lesson is that tactics are important at all levels of play, not only for beginners.  You won't ever reach a stage where you've "fixed" the problem: even if you have a master-level understanding of strategy, you still need to be on the guard for basic tactics.
The term was made popular by John Nunn's book "Secrets of Practical Chess".  He describes a friendly match of 100 rapid games where he beat a 2300-rated player by 88-12:

"I thought that I would see lots of advanced strategic concepts in these games but actually all I have learnt is LPDO" ... During the remaining games I saw what he meant. Most of the games were decided by relatively simple tactics involving undefended pieces, when the LP would duly DO.
Answer: Brian's answer gives you the "why". I will add a bit of "when not", as this, as usual, is a rule of thumb which happily may be ignored by a stronger player. Thus, the limitations of the rule...

Does not help at all against attacks of pesky pawns (assuming "piece" meant "officer") or more generally, light force kicking your heavies around.
Overprotecting everything makes your position somewhat cramped.
Protection is a liability that limits the agility. Good luck mating with each and any piece protected at all times!
Might be in clash with other rules of thumb. E.g. using the "bulls head" (e4 d4 Nc3 Nf3 Rd1 Re1) your bishops must go to b5 and g5 by this rule, which are usual good squares anyway, but sometimes c4 and f4 are fine or even better. BTW, in the latter case protecting them with pawns to b3/g3 by the rule is more often a bad idea than not!

Also as usual, don't worry - eventually you get stronger and know by yourself when and how to follow the rule in spirit, not in letter.


problem accessing network through terminal

Question: I am using ubuntu 10.04 and I am having trouble accessing my Internet through terminal, while I am able to access it through browser.
In terminal, if I try to ping any server with its name, like ping google.com, I am able to do that, even I can successfully used nslookup and several other network commands, but when I tried to download something, using  "wget" or install something using "gem install" or checking out some code using "svn", I got server timeout error.
Can anybody help me figure out the problem.
Thanks
Comment: Maybe the server is down ?
Answer: If you're not sure if a particular server is up, you can try running its address through http://downforeveryoneorjustme.com/.


Way to set up a list, where depending on permission, admin will see all

Question: I'm trying to setup a list where an "Admin" can see all entries but a user can only see their own?I found this YouTube video by SharePointQuester and all he is using are web parts with different views and setting the permissions on the views (https://youtu.be/exVN5S89KTc).

It seems like what I am looking for.  One of the List views (the Users) will have the filter set to [ME].  Then there is another view for the Admin with no filter.

So I guess my question is, I can just base permissions and what folks see by the way I filter views, then put them in a group that controls the access to the views?  There is nothing non-OOTB solution needed for this (don't need to make it a 'code' solution).
Answer: What you describe is one way of doing what you are looking for.
But OOB, lists have the ability to automatically filter the list so that 'regular' users can only View and Edit the items they created - this is applied to All users unless they have the 'Cancel Check Out Permissions' (i.e.: what you term 'Admin' users) See yellow portion of the attached image.
You can regulate what the 'regular' users see in the sections circled in green and red in the attached image.
The benefit of using this over applying permissions on different views is that you only have to manage permissions for two groups, not permissions AND views as per your question.
<code>Please mark this as answer if it helped you
</code>
get to this setting by going to list options —> Advanced Settings
Comment: @a-k-a-fritz, thanks, this did answer my question.  I'll have to tweak because now the customer wants it so that instead of the individual seeing their own, everyone in the individual's group can see their group entries.  I'll mark it as an answer.  Thanks!


Is Mist Wallet a node on the Ethereum network?

Question: I am new to Ethereum.  I've just installed the Mist Wallet, and I find that it keeps the CPU running HOT.  Is the wallet a node on the Ethereum Network?  If so, should I be able to mine stuff?
Answer: If you run the Mist wallet you run a node.

I find that it keeps the CPU running HOT

The reason should be that your wallet is syncing to the blockchain.

should I be able to mine stuff?

I've made my small research and I haven't found any proofs that you can mine using the Mist Wallet and have a reward for your work. People suggest connecting to mining pools and using software like Claymore or Ethermine if you actually want to mine and be rewarded.

Ethereum Reddit similar question.
From Beginner's Guide to Ethereum Mining in 2017 - How to Mine Ethereum on Your PC.


File protection in Unix

Question: Is there a way to protect a file in such a way that even root cannot delete it or rewrite it after creating it?
I have a file which is created by root under /var/log/ and I want to restrict all users (including root) so that they can just read this particular file after it has been created.
Comment: This is not a duplicate of [How do I make a file NOT modifiable?](http://unix.stackexchange.com/questions/67508/how-do-i-make-a-file-not-modifiable)! This question asks for something that root cannot undo. The other question only addresses the cooperative case.
Comment: If you want a way to stop even root, completely, then you need mandatory access control. see en.wikipedia.org/wiki/Mandatory_access_control It may however be more complex than you need. Protecting the one file is not enough, as a change to any significant system file could be used to circumvent it.
Answer: No there is no way to do this, to my knowledge. The answer about chflags pertains to BSD variants. A similar command for Linux is chattr.

http://en.wikipedia.org/wiki/Chattr

The concept of the root user is that they can do anything on the system.
Answer: You may be looking for the "system immutable" flag.  The details may depend on precisely which operating system you're running, but the basic idea will be the same.  You'll want something like this in BSD (or OSX):
# chflags schg /path/to/file

or the equivalent in Linux:
# chattr +i /path/to/file

Note that root can always remove the system immutable flag in order to change the file, so your next option is to place the file on a read-only filesystem.  Even so, with root access one might still be able to unmount a read-only filesystem and mount it read-write.
The next step would be to put it on a physical disk that has a write protect switch.  Check with your vendor to see if this is available with your hardware.  If it is not, you could consider putting the files on a WORM drive of some sort.  A CD-R is an option.
What about putting the file on a read-only NFS filesystem stored on another server?
Probably easier to figure out a better solution to this XY problem.
Comment: chflags is for BSD variants, chattr might do what you want. http://en.wikipedia.org/wiki/Chattr
Comment: It is a modified version of SUSE Linux. Not sure if this command is available in it. I will check it later.
Comment: @slm, good catch, I guess I'm showing my colours. :-)  I've updated my answer.
Comment: or write to /dev/printer
Answer: Generally speaking, root can do everything. Whatever steps you take to prevent root from doing something (such as setting file attributes), root can undo.
OpenBSD and FreeBSD have a notion of security level, also known as securelevel. The securelevel is an integer value. If the value is negative or 0, only the usual unix security rules apply. At securelevel 1 and above, a number of restrictions come into place, in particular:

It is impossible to reduce the value of the securelevel.
It is impossible to load or unload any kernel module. Thus the code running in kernel mode cannot change anymore.
Raw access to the memory or block devices is disabled.
The chflags system call denies attempts to remove the immutable or append-only flags from any file.

Securelevels 2 and 3 add additional restrictions. The important thing is that it is impossible to reduce the security level without rebooting, even with root access. Thus securelevels bring in restrictions to what root can do, at the expense of making certain maintenance tasks impossible (such as repairing or reconfiguring a RAID array).
Of course these restrictions are only effective against users who do not have access to the physical machine or to a console during boot. The bootloader data (including the kernel file) must be immutable, otherwise a root user could introduce a backdoor and trigger or wait for a reboot.
It may be possible to configure something like this with Linux's security frameworks (AppArmor, SELinux, …), but these are primarily tools to set restrictive policies for processes that are not running as root. If it is at all possible, it would require a lot of care in defining the policy (even in the ordinary case, designing useful policies is hard).
If you don't have the option to restrict root's power in this way, the way to make a file read-only for root is to store it on a different system. Options include:

Run the system in a virtual machine and store the file on the host.
Store the file on another system accessible via the network.
Store the file on a physically read-only media.
Answer: Seems like the only valid way is to use chattr command as follows:
chattr +i /var/log/file

This way even root cannot modify the file unless it removes the i attribute from the file.
So it is just one step toward a better protection I think.
Comment: I would consider it useless protection, but if you must 8-)
Comment: I agree...! ;-)
Comment: "root cannot modify the file unless it removes the i attribute from the file". Or in other words this doesn't actually solve the problem.
Comment: @Gilles OK true; is there a solution though?
Comment: @coffeMug Not on Linux, as far as I know. See my answer for an answer on FreeBSD and OpenBSD.
Answer: Will the file be frozen, or do you need to keep writing to it? In the first case, you could put the file on a read-only medium: CD-ROM, flash drive with a physical write-protect switch, etc. (That protects the integrity of the file, but wouldn't prevent root from unmounting it and/or masking it with a fake).
If you want to continue writing to the log file, there's no solution unless you can find a write-once-read-many physical medium: If a file can be written to, it can be overwritten. (For completeness: It is possible to set a file's "append-only" attribute with chattr or chflags, which will protect the file contents from being overwritten. But it is not possible to block root from unsetting this attribute.)
Answer: chattr can do this, or at least something pretty close to it. There are two attributes that may be relevant, depending on what exact behavior you want.
For example, you may want to set the a attribute, using chattr +a filename:

A file with the `a' attribute set can only be open in append mode  for writing.    Only   the   superuser   or   a   process  possessing  the CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

Since this would seem to be a log file, that may be the more appropriate option. Or you can use the i attribute:

A file with the `i' attribute cannot be modified: it cannot be deleted or  renamed,  no  link  can be created to this file and no data can be written to the file.  Only the superuser or a process  possessing  the CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

Note that the superuser can clear these attributes with the corresponding chattr -X command.
Comment: "`chattr` can do this" — where you mean "`chattr` **cannot** do this", since root can do `chattr +i`.
Comment: @Gilles I'm not sure what you're getting at; even the OP's self-answer specifically mentions `chattr +i`. Even root cannot modify immutable files *as long as the immutable attribute is set*. I don't think there's *anything* that root can do that root cannot undo. (Well, maybe encrypting the file and throwing away the decryption key could work, but I don't think that's very useful...)
Comment: Just because it's a self-answer doesn't mean it's correct. On OpenBSD and FreeBSD, there is an immutable flag that root cannot unset, if the OS is configured for it (which implies a trade-off between security and ease of maintenance). See my answer for details.
Comment: @Gilles Of course a self-answer is not necessarily correct, but in this case it does state that chattr is a "valid way" to do what the OP is trying to do. (It was also posted about ten seconds before my answer, which is a big reason why I'm leaving my longer answer around.)
Comment: And in the comment exchange: "this doesn't actually solve the problem." — "OK true". Your answer, like coffeeMug's, would be ok for the duplicate question, where a cooperative solution is good enough. But this question requests security from root.
Answer: This doesn't answer the exact question asked, but an alternate solution is to have the log live on a different server / VM, make it append-only using chattr +a and then mount it over the network.  This is not without drawbacks, but in my opinion is one of the best approaches to solving this problem.

File protection in Unix


Is there any evidence to suggest that subatomic particles have 3D physiscal size?

Question: What I'm asking is do subatomic particles like a proton have a volume or any 3 dimensional size? Or are they just points?
Comment: Related, duplicates: http://physics.stackexchange.com/q/119732/50583, http://physics.stackexchange.com/q/102791/50583, http://physics.stackexchange.com/q/66779/50583, http://physics.stackexchange.com/q/41676/50583
Comment: Also related: http://physics.stackexchange.com/q/14343/ http://physics.stackexchange.com/q/176373/ http://physics.stackexchange.com/q/197983/ and probably other questions relating to proton (or nucleon) form factors and structure functions.
Answer: Protons and neutrons are extended object, being roughly $1\,\mathrm{fm}$ in radius. Give or take a bit, depending on how you want to define their size.
Evidence for this comes in three basic forms: first from scattering experiments in which we bounce other particles off of them (electrons are particularly good for this applications); second from packing experiments (AKA seeing how the size of large nuclei depends on the number of nucleons); and finally the fine details of the hydrogen atomic energy levels (which depend in a small degree on the charge distribution of the proton). However, the second sense depends on measuring the size of the nuclei which comes back to scattering experiments again, so in a sense they are the same.
So, how do the scattering experiments work?
Well, if you are doing electron-proton scattering the interaction is electromagnetic in character. So, for any given electron energy you can calculate the distribution of scattering angles that would result from sending a beam of electron at a proton target (a thin-walled can containing liquid hydrogen in most cases) *under the assumption that the proton was point like.
Then you run this experiment over and over again at different energies and you see that your results agree without your calculation at all energies up to some threshold above which they disagree and you get fewer hard scattering event that you predicted.
Finally you calculate the distance of closest approach for electrons with the threshold energy and you take that as an approximation to the charge radius of the proton.
Answer: The elementary particles of the Standard model are pointlike. This has been determined by numerous experiments. All other particles except the ones in the table are composites of some of the ones in the table, and these have dimensions that have been measured using scattering experiments to find their form. Here is an answer on how this is done.


Installing Fedora 24 in dual boot mode not working

Question: I'm trying to install Fedora 24 side to side to Windows 8.1. I previously was running Debian 8 next to Windows and wanted to swap to Fedora. I'm trying to install from a USB live distro; some info:

The ssd has two windows partitions and about 90GB of unallocated space.
If I choose the automatic partition option, the installer complains that there is no free space available.
If I partition the space myself, the installer complains about not having a /boot/efi partition available (even if I specifically allocate one in the installer).
It's an ASUS motherboard and I've got fastboot disabled.
I also deleted the PK keys to disable secure boot and choose other OS in the secure boot bios option.

Running sudo gdisk -l /dev/sda from the Fedora live stick gives the following output:
GPT fdisk (gdisk) version 1.0.1

Partition table scan:
  MBR: MBR only
  BSD: not present
  APM: not present
  GPT: not present

***************************************************************
Found invalid GPT and valid MBR; converting MBR to GPT format
in memory.
***************************************************************

Disk /dev/sda: 488397168 sectors, 232.9 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 70D91666-A3FE-4C49-A75B-76546492EDF4
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 488397134
Partitions will be aligned on 2048-sector boundaries
Total free space is 190208301 sectors (90.7 GiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048          206847   100.0 MiB   0700  Microsoft basic data
   2          206848       297166847   141.6 GiB   0700  Microsoft basic data
   3       297166848       298190847   500.0 MiB   0700  Microsoft basic data

Partition number 3 was an attempt to create a NFTS partition from Win 8 to use for /boot/efi which wasn't successful and didn't make any difference....
Any idea what else I could try?
Answer: So I don't know why it seems much easier to find an answer once you wrote down the question.... (thanks Ahmad)
I stubbornly booted the USB by selecting the option with the 'UEFI' prefix. Choosing the option without it fixed my issue...


What does punk in steampunk mean?

Question: There's an earlier question about the definition of steampunk, but the answers gloss over the 'punk' part of it, except for vaguely connecting it to cyberpunk. So is there any significance to the 'punk' part, or is it just a buzzword kind of thing?
Comment: The *real* question is: "What does **steam** mean?"
Comment: I think, as some of the answers suggest, the Punk part of the name has slightly changed/lost its original meaning. But the theme of rebelling against what's normal is definitely a part of Steampunk. A rejection of the status quo, embracing your own style and theme in your life, a certain DIY attitude. Self-expression as rebellion.
Answer: The -punk in both cyberpunk and steampunk came from the punk in punk music, where punk originally referred to urban, raw, ugly, obnoxious, disillusioned, and disenchanted ~4 member rock bands who literally didn't know how to play their instruments and, subsequently, (post-punk) signified more or less that, but with more "cool" and a bit less "butt-ugly" to it as everyone learned to play and cultivated their image.
Your linked Q&A mentions that K. W. Jeter coined the term steampunk as a sly nod toward cyberpunk.  To elaborate on that, people at the time saw Jeter's Dr. Adder as a cyberpunk novel--indeed, more punk (dystopian, urban, raw, and ugly) than most.  And The Glass Hammer was even more clearly cyberpunk (i.e. it had a somewhat more explicit connection to computing).  So for him to write Infernal Devices and coin the phrase steampunk to describe dystopian, urban, raw, ugly life in the steam age made complete sense.
The next two popular authors who claimed to be writing steampunk were Bruce Sterling and William Gibson.  Their dystopian Victorian novel, The Difference Engine, although not  as raw or ugly in outlook as Jeter's work, made computing an explicit theme and had a direct connection to cyberpunk in that Sterling and Gibson were both foundational figures in the sub-genre.  So the label steampunk there made perfect sense as a pun.  And what Sterling and Gibson had really done in cyberpunk was romanticize hacking.  Their worlds were dystopic enough that you wouldn't want to live there, but the computer hackers who did were usually very "cool."  So whether cyber- or steam-, they were writing technology in a way where you appreciated the machinic, knobbly, wiry, greasy bits for being sort of punk--at least, urban and ugly but still pretty cool.
The publication of The Difference Engine was a big event at the time, because Sterling and Gibson were huge, and that's really the book that--even though it wasn't so great--got the world to think of steampunk as a potential sub-genre itself.
Incidentally, Gibson once mentioned listening to Joy Division over and over while writing Neuromancer, so even though the term cyberpunk originated elsewhere, the -punk wasn't completely inaccurate or imaginary in relation to his work.
So while punk music had a very, very small but direct connection to cyberpunk and an obvious overlap in tone with cyberpunk, the connection to steampunk is a lot thinner, and all the -punk means (if anything) is that the steam age technology in it will be romanticized and cool ... and maybe just a bit gritty.
Comment: To me the term cyberpunk is also very reminiscent of early hacker culture, especially in East Germany, where young hackers often performed hacks for the KGB or private clients and hustled enough money to afford themselves their relatively expensive computer hardware but were otherwise living as squatters as part of the same punk scene which featured sex, music, drugs, and counter-cultural values. And even in the west, hackers embodied the same rebelious punk rock spirit (anarchism, communalism, political subversion, etc.) taking pride in living in the margins of society.
Comment: I like that you mentioned the Joy Division connection re: *Neuromancer*. Joy Division straddled punk and post-punk and seeing them live was way more hardcore than their albums would suggest (just saw Peter Hook in Oct). I've always thought that cyberpunk and steampunk are so disparate that I can't really see a tether between the two, although it sounds like historically there might be a fine line connecting them. It's been said that cyberpunk is an aesthetic while steampunk is a lifestyle. I'm still trying to figure out where punk and hacking crossed paths? Like, what years?
Comment: I've always considered steampunk more of an aesthetic (probably because it has such stereotypical imagery), whereas cyberpunk has more anti-establishment and countercultural undertones without as iconic of imagery associated with it. But then I'm not much into steampunk literature, so maybe true steampunk does have strong punk-like sociopolitical themes, and I just haven't been exposed to it. But I can picture very happy-go-lucky non-dystopian steampunk (would this be considered pop steampunk?), whereas I can't picture cyberpunk not being incredibly subversive.
Answer: I believe the word punk is being used in "steampunk" and "cyberpunk" to refer to a dark gritty version of the prefixed "steam" and "cyber" terms. When cyberpunk started it was different from a lot of the science fiction to date because of how dirty and gritty the worlds and people inhabiting them were. That along with a "no future" or bleak future oultook tends to be a big driver in early cyberpunk.
In steampunk what I have seen are people embracing the punk portion with wild ideas that do not follow the norm. In this case "punk" is being used to mean "different" or to identify themselves as outsiders.
Comment: Sorry for my poor wording. I meant "punk" refers to a dark gritty version of "steam" or "cyber" if that makes any sense.
Comment: Cyberpunk predates steampunk, so shouldn't that be "refer to a dark gritty version of the latter"?
Answer: While Steampunk as a science fiction/fantasy genre is an outgrowth of cyberpunk, as a social, cultural phenomena it has a strong connection to punk music in its DIY ethos.  Steampunk frequently features handcrafted one of a kind creations and/or modifications similarly Punk music culture placed a premium on self-production of music, fashion and fanzines.
Answer: From http://forwhomthegearturns.com/steampunk-whatsinaword/

"The "punk" part of the term has to do with the rebellious spirit and a Do-It-Yourself attitude that goes hand in hand with innovation. Early science-fiction writers like H.G. Wells and Jules Verne would have classified themselves as 'futurists' because their stories pushed the boundaries of technological innovation and explored new way humans can interact with their environment. The term Steampunk, of course, did not exist until long after stories like The Time Machine and 20,000 Leagues Under the Sea were already classics, but these authors provided the seeds that would some day branch into a popular genre that includes not only books, graphic novels and movies, but fashion, artwork, and handicrafts.
Answer:
There are a lot of theories surrounding the punk nature of steampunk. Is it called punk because of its close association with the cyberpunk genre? Or is it called punk because of the do-it-yourself attitude of the people associated with this genre? To answer these questions, it is important to first understand a little bit about the origins of this word and how it was adopted into other alternative cultures and art forms.

Origin of the word punk

The word punk has always been a controversial label ever since it was first used in the 1970s. It was first used as a generic music label to describe anarchic and irreverent bands such as Television, Sex Pistols, The Clash, and many more. Most of the punk bands rejected the mainstream elements associated with 1970s rock and created short and fast-paced music. The songs contained hard-edged melodies and the lyrics usually contained political and anti-establishment themes. Most of the bands would self produce recordings of their work and distribute them independently through individual record labels. This gave rise to the DIY ethics which are associated with this genre. By the late 1970s punk had become famous in the UK and was turning into a cultural phenomenon. People were expressing themselves with distinct types of clothes such as T-shirts with offensive messages written on them, jewelry, spiked or studded jackets, and bands and, harsh and gritty looks.

'Punk' in Literature

The first time the word punk was used in literature was by Bruce Bethke when he published a short story called 'Cyberpunk'. William Gibson later provided definitive elements for this genre in his works called 'Neuromancer'. In this case, punk worked as a fictional style of combining elements such as gritty, downbeat, low-life punk attitudes with cyberspace, cybernetics, and other futuristic technologies. The recurring theme for cyberpunk usually visualizes a collapse in society, which leads to social disparities and people trying to overthrow the imposing authorities.

The cyberpunk genre has often been seen as the inspiring force for a lot of other genres in the science fiction community. The most common being biopunk, nanopunk, and yes most definitely steampunk. The term was first used by K W Jeter in the late 1980s. K W Jeter was, at the time, a well-known author in the science fiction community and was known for his cyberpunk works such as Dr. Adder, The Glass Hammer, and many more. He coined this term jokingly as he was trying to find a suitable word for some of his works which were based on anachronistic technologies and the Victorian era. He came up with the word steampunk as steam was the main source of power during this era and would perfectly compliment the retrofuturistic theme as had been the case with its futuristic counterpart, cyberpunk.

Even though the word was borrowed from its famous counterpart, cyberpunk, steampunk literature can be traced as far back as1870s and 1890s to the works of Jules Verne and H.G. Wells. These early science fiction novels were considered to be the forerunners in providing the aesthetics associated with this genre that we see today. Other authors such as Michael Moorcock, K W Jeter, Bruce Sterling, etc. increased the visibility of this genre by providing descriptive narrations in their works. 'The Difference Engine' by William Gibson and Bruce Sterling (1990) is considered by many to be one of the best steampunk novels while providing a lot of rigorous details and having compelling characterization.

Evolution of Steampunk into subcultures

Steampunk is a particularly compelling visual form of fiction that is often set around retrofitted technologies in an industrial era of steam power. Due to in part of its visual appeal and its alternative take on science and technology, steampunk has been one of the popular genres to be translated into other forms of media such as television, films, comic books, video games, etc. This is one of those rare sub-genres of science fiction which also made a footnote in other performative subcultures such as music, fashion, arts and crafts, and gaming.

Nowadays the fanbase of this genre has also moved on from discussing popular literary works to a more cohesive community that discusses arts and crafts, clothing, and other lifestyle choices. Ever since its popularity in the early 2000s, steampunk has attracted people interested in creative arts. Steampunk has one of the largest communities of DIY arts that create some of the most unique and innovative steampunk designs. Some of these designs have a compelling visual appeal and at the same time can also have a function in their daily life.

The steampunk community also consists of people who are fashion enthusiasts and display their extravagant costumes at cosplay and steampunk-themed events. Early fans of steampunk fashion usually hand-made and designed every aspect of their costumes including accessories. Nowadays you can find stores, both online and on land, dedicated to providing the most aesthetically beautiful steampunk clothes and accessories.

So is there a punk in steampunk

Now that we have simplified what punk was all about, we can try to identify the point of intersection between punk and steampunk. Punks usually identify social disparities and are against social norms. Steampunks are also similar in the sense that they recognize the social disparities of the Victorian era and try to reject the social norms of this era. For example, men and women alike adorn amazing steampunk personas of explorers, pirates, air marshals, scientists, vigilantes, etc. This was not the case in the Victorian era where women were usually housewives.

Many steampunk fans also create their own steampunk aliases which they use as a getaway from their everyday lives. These fans not only create personal characters but also have different personality traits when adorning these characters. They use their love for steampunk as a way to break free from the existing social norms and explore the world from a new perspective.

Apart from this steampunks are also well known for tinkering and creating unique designs, sculptures, artwork, etc. They have a diehard DIY attitude towards the existing technologies and their designs range from creating new inventions to redesigning existing technology to suit the steampunk aesthetic.

Even though steampunk may not have the gritty and harsh aesthetics of the punk movement which happened during the 1970s, it certainly captures the essence of the movement in terms of its disregard for social norms and the diehard do-it-yourself attitude.

Source : https://allaboutsteampunk.com/what-is-punk-about-steampunk/
Comment: Hi and welcome to the site. Please take the [tour] and visit the [help] if you haven't already. I've noticed you've copied the entire text from the website, but not properly attributed that ever single paragraph is lifted whole sale. Could you perhaps summarise *in your own words* an answer to your question then use `>` to highlight only the most relevant quotes? Thanks
Comment: For now I've put all the text from the site down as quotation blocks, so there's no confusion to whoever comes across this question

What does punk in steampunk mean?


Updating images (using File ft) within a Grid updates other File fields

Question: I'm finding, since updating to EE 3.4.0, that when I have a Grid field of rows, each with a File field (to upload an image), I'm finding that updating one File field is then updating other File fields on the same page (some not even in the Grid field) with the same image. I then switch the other File field back to the image it should be and the first one switches to this one too - it's making it impossible to update entries, and has only been seen since upgrading EE to v3.4.0.
Answer: Found the solution - https://support.ellislab.com/bugs/detail/22018/FilePicker-callback-methods-stacking-and-being-run-when-they-shouldnt
Will be fixed in EE3.4.1 - relates to a Javascript file messing with the File field


How do I find out which accounts have not been imported when using the Import Wizard?

Question: Using the Import Wizard I performed an import using the Account Name and a custom field which contained 171 records in total. When I ran the import I got an email stating 56 had failed but the csv attached to the email is empty so I can see which records this has failed against.
Is this a known issue or do I need to do something else?
Answer: If you are the System Administrator you will be able to see the Bulk Data Uploads page which contains a link which allows you to download a results file for the data upload. This contains the record id for the successful uploads and the errors for the failed records. Unfortunately it does not include the full text of the records unlike the Data Loader error files however you should be able to find the values in the source file that have caused the errors.


Plastic Bowl for Bread

Question: Is it ok to let bread rise in a plastic bowl?  I got rid of my glass and metal bowls because they were too heavy for me to lift.
Answer: It really shouldn't be a problem.  A thick-walled bowl is usually preferred to help maintain an even rising temperature.  As long as it is food-safe, you keep it in a draft-free area, and it remains at a consistent temperature, you should be fine.
Answer: It's not just OK, it's preferable.
If you walk into the back in a commercial small bakery, you'll see that pretty much all of their doughs rise in plastic rising buckets. The first advantage of this is that such buckets have snap-on lids that eliminate the need to waste a lot of plastic wrap sealing in the dough.  The second advantage for bakeries (but probably not for you) is that they can be stacked.
The third advantage I can only give you from experience (I can't find a reference): the dough rises faster.  I believe this is because unlike metal, ceramic, or glass, the bowl does not conduct away the heat of the fermenting yeast.  Presumably a dough basket (another option for you in the "easy to lift" department) would work just as well.
Comment: Such great information, I appreciate your information.  I was aware that  bakeries use plastic buckets with lids but it just didn't occur to me to apply that to myself!
Comment: Thanks!  If that satisfies you, can you select my answer?
Comment: I would be happy to select your answer but I don't know how to do that,  a little instruction please?
Comment: Looks like you just figured it out!

Plastic Bowl for Bread


Confusion about replicating a call option

Question: Assume standard Black-Scholes model,
$$dS(t)=S(t)(rdt+\sigma dW(t))$$
where $\sigma$ is a constant and $W(t)$ is a Brownian motion under the risk neutral measure.
A call option is replicable, so if we are long a call and continuously (in theory) trade according to the negative of the delta of the option, we should in theory end up with 0 at the end since the two positions cancel out, and this is how we determine the price of the call option. There is one thing I do not understand here. Among the input parameters in the Black-Scholes model, $\sigma$ is treated as a constant, so there is no Pnl associated with $\sigma$; we are delta neutral so there is no Pnl associated with $\delta$ as well, and since we hedge continuously, there is no gamma Pnl (I guess?); but why do we not have a Pnl associated with theta in this case since theta is not hedged?
Answer:
In Black Scholes
$$\frac{dS}{S}=rdt+\sigma dW$$

$dC_{BS}(S,t)=\underbrace{\frac{\partial C_{BS}}{\partial t}dt}_{Theta PnL}+\underbrace{\frac{\partial C_{BS}}{\partial S}dS}_{DeltaPnL}+\underbrace{\frac{1}{2}\frac{\partial^2 C_{BS}}{\partial S^2}dS^2}_{GammaPnL}$

$dC_{BS}(S,t)=\frac{\partial C_{BS}}{\partial t}dt+\frac{\partial C_{BS}}{\partial S}dS+\frac{1}{2}\frac{\partial^2 C_{BS}}{\partial S^2}\sigma^2S^2dt$

Note that $dC_{BS}(S,t)$ is only the PnL of option that exists in BS world, since the spot $S$ follow BS dynamics

Assuming zero rates dividends, $\theta_{BS} = -\frac{1}{2}\Gamma_{BS} S^2 \sigma^2$

Delta hedged option PnL in BS world = $\frac{1}{2}\Gamma_{BS} S^2 [(\frac{dS}{S})^2-\sigma^2dt]= \frac{1}{2}\Gamma_{BS} S^2 [\sigma^2dt-\sigma^2dt]=0$

It makes sense since $S$ follows BS dynamics, if you hedge acc to BS delta, your PnL is indeed zero, since theta PnL is offset by gamma PnL

However, this spot $S$ follows BS dynamics which is not true in real world

In real world, spot $S$ follows unknown dynamics

Denote $C_{mkt}(S,t)$ as market price of option at spot $S_1$ and time $t$

$dC_{mkt}=C_{mkt}(S_1,t_1)-C_{mkt}(S_0,t_0)$

$_{mkt}=\underbrace{\frac{\partial C_{BS}(S,t|\hat\sigma)}{\partial t}dt}_{ThetaPnL}+\underbrace{\frac{\partial C_{BS}(S,t|\hat\sigma)}{\partial S}dS}_{Delta PnL}+\underbrace{\frac{1}{2}\frac{\partial^2 C_{BS}(S,t|\hat\sigma)}{\partial S^2}dS^2}_{GammaPnL}+\underbrace{\frac{\partial C_{BS}(S,t|\hat\sigma)}{\partial \sigma}d\sigma}_{VegaPnL}+\underbrace{\frac{\partial^2 C_{BS}(S,t|\hat\sigma)}{\partial \sigma\partial S}dSd\sigma}_{VannaPnL}+\underbrace{\frac{1}{2}\frac{\partial^2 C_{BS}(S,t|\hat\sigma)}{\partial \sigma^2}(d\sigma)^2}_{VolgaPnL}+...$

Spot/vol correlation would generate vanna P&L, e.g. plot VIX log return against SPX log return would get a -70% correlation

Vol-of-vol would generate volga PnL

It actually means you pay theta for gamma, vanna and volga

More sophisticated models like LV/SV tries to address these mkt phenomenon
Comment: Empirically do you find SV and SVJ model accurate?  Like increase in vol of vol actually leads to steeper smile and changes in spot/vol correlation leading to changes in skew?  I've always been curious about this but don't have access to data.
Comment: Actually you don't need too many data, you can start with SPX options quoted on CBOE [http://www.cboe.com/delayedquote/quote-table-download] Start with a simple SV model like Heston's model, calculate vanilla prices for various strikes and expiries with the SV model, and translate prices to a IV surface fitted by the model. Play around with the parameters (spot/vol corr, vol-of-vol, mean reversion rate, long run average of variance) and see how well SV can fit the market's IV surface. Skew in SV is essentially a product of spot/vol correlation and vol-of-vol, Smile is generated by vol-of-vol
Comment: You will see SV models don't have enough skew for short expiries. Also since you only have 4 parameters available, you won't be able to fit the market's iv surface. Jump parameters are hard to estimate. Unlike parameters like spot/vol correlation, vol-of-vol, which can be traded with risk reversals and butterflies, jump parameter is not really tradable. So jump models are not so popular among practitioners
Comment: Hello, I know in the model when you change parameters it shifts the skew.  I also have read that Heston doesn't fit market that well.  My question was empirically, when vol of vol changes or more importantly when spot/vol corr changes do actually option skew change accordingly.  For example, usually they're seems to be a relationship between implied vol and realized vol with implied vol a bit lagged.
Comment: My question is, when we see realized vol/vol increase do we also see the wings get bid at the same time in actual options.  I guess what I am curious about is how does the implied model parameters correlate with empirical data.  I don't think IV can predict FV but I haven't done the research but I think HV can predict IV to some extent.  Wondering if there was anything to be said with vol/vol and wings and spot/vol corr and skew
Comment: Basically when you plot historical volatility against IV, they tend to track.  Just wondering if it's the case with other parameters.  In svj model, if we suddenly have more after market moves, do wings actually get bid more?  I have my own beliefs on this stuff but curious what the data says.
Comment: For example, we could find 2 market periods.  One where most moves occur over night and one where most moves occur during the day.  Is the smile more bid in the former scenario or not.  Are there papers that show this?
Answer: When you replicate the option, you negatively scalp yourself when hedging deltas (if you are short the option).  That negative scalp should be offset by theta you make by being short the option, and thus on net your option + hedge has 0 pnl.  This obviously assumes realized volatility = implied volatility.
If your option has high IV but underlying doesn't move, then obviously you will lose/gain money on theta (depending on long/short option) but you would have 0 PnL change from underlying hedging.  In this scenario, realized volatility < implied volatility.  Also in this scenario, option is "mispriced" and hence there is non-zero PnL.
Obviously this all assumes option prices follow BSM model, so just take everything with a grain of salt when you enter the real world.  And if you approach options from a P or Q perspective.
TLDR: Options make lose money from theta, underlying make lose money from gamma.  Under BSM, if IV = RV, then they cancel out and net PnL is 0.
Comment: could you explain what you mean when you say: "you negatively scalp yourself when hedging deltas". or maybe a simple example would help. thanks a lot.
Comment: You are short a call option, let's say ATM so you are short -50 deltas.  To hedge it, you have to buy 50 underlying.  In the BSM world, if the underlying moves up in price, your call gets even shorter deltas, so now let's say the call is now -60 deltas.  To hedge that you have to buy 10 more underlying, but you will now have to buy it at a higher price than before.  Now let's say the underlying moves back down in price to where it started and the call option once again has -50 deltas.  You are long 60 underlying, so you have to sell 10 more to hedge your position.
Comment: But now you sold at a lower price.  And thus, as you hedge your option by buying/selling the underlying, you are negatively scalping yourself because you are buying high, selling low.  Being short the call, you hope that this negative scalp is offset by the theta you collect from being short the option.
Comment: Obviously everything in BSM model is in continuous time, but the effect is still the same.  The gamma in the call option creates delta mismatches (with your replicating portfolio) and if you are short an option, you negatively scalp against your self.  If you are long the option, you positively scalp against your option.  If you look at BSM greeks, theta and gamma are linked hand in hand.  High gamma options must have high theta because theta must offset trading the underlying.
Comment: thanks a lot. I never worked with options (only read books) so I will print out and study it carefully. thanks for through and clear explanation. this is definitely related to a different question that I asked a few weeks ago in a different thread so it will help with that one also.
Comment: No problem. If you are good at programming you could simulate the option and replicating portfolio and keep track of the trades and pnl.  Setting volatility and IV the same, net pnl on average should be 0
Comment: gotcha. I remember reading somewhere that the cost of the hedge is equal to the value of the option. Otherwise, there would be an arbitrage. The best book I ever read on options was cox and rubenstein. Recently I started reading the book by Sinclair which is also good but has  totally different  focus compared to C and R. All the best and thanks for your clear explanation.


Resources for learning music theory whilst doing other things?

Question: I spend about 2 hours a day driving in my car, along with a few hours sat at a desk working. I was wondering if anyone can recommend some good audio to listen to (e.g. Podcasts, ear training exercises) that can help learn music theory, without requiring me to look at a screen or have an instrument in front of me? (I know this will limit the options somewhat)
Comment: See also [Music education audio lessons](http://music.stackexchange.com/questions/2975/music-education-audio-lessons)
Answer: With most things it is good to try and multitask.  When learning new things it is not good to multitask.  If you are doing two things, only 50% of your brain will be dedicated to learning, and you'll learn half as much material half as well, and you'll be half-satisfied because of it.
My philosophy is that if something is really important enough to you, you'll make the time for it in your day.
Aural skills and music theory are two entirely separate enterprises.  For the former I recommend you get a solfege book and learn to sing.  For the latter I recommend getting a theory text and workbook and going through it cover to cover.
Comment: I often find that if I try to listen to spoken text at work, I'm either concentrating on the text (and not working), or I'm concentrating on my work and reach the end of the text with no comprehension or recollection.  I don't think you'll be able to make this work; most music theory requires full concentration (and a pad of music paper) to really get to grips with.  As far as ear training, you're going to be singing sol-fa or whistling which you can't (shouldn't ;) do in an office full of people.
Comment: Thanks for he comments. I was hoping there may have been some way of utilising the time I spend stuck in traffic, but if, as you say, it needs full attention, I'll put the time aside elsewhere. I've come across the software GNU Solfedge, so I may start giving that a go and see how I get on.
Answer: I second jjmusicnotes, in that music theory is not particularly amenable to passive learning. Particularly if you have any intention of using the theory to understand or compose music. It's going to rewire your brain if you do it right.
I recommend taking the plunge and signing up for a Freshman-level Music Theory course at your local State U or Community College. These almost always have an accompanying Aural Training/Listening Lab component. And being Freshman-level, have few or zero prerequisite requirements (just the desire to learn).
If you're like me (and many other musicians) self-discipline is a major issue in such a big undertaking. Being forced to show up every day will really help you keep up with it.


R2R DAC in reverse

Question: Knowing how voltage dividers work, this probably isn't possible. But, is there a way to run an audio signal back through an R2R arrangement and get 8bit digital signals back out without complex circuitry?
Comment: You can turn any DAC into an ADC by adding an analog comparator.
Comment: Where would I add it? Elaborate please.
Comment: Connect the DAC to one input, connect your analog voltage to the other, and connect the output to your logic. The logic (e.g., firmware running on a microcontroller) then runs an algorithm such as [successive approximation](https://en.wikipedia.org/wiki/Successive_approximation_ADC) to determine what the analog voltage is.
Answer: I think you're looking for a Flash ADC:
https://en.wikipedia.org/wiki/Flash_ADC
You can't use the same arrangement though. You need a lot more resistors.
Comment: Makes sense. I'm guessing there isn't a way to do it without some form of an IC?
Comment: You could build the comparators out of transistors, but that sounds kinda painful. ICs make things easy!
Comment: Im for the ICs most of the time but a 6502 and the VIA plus some other bits and doodads and you suddenly find yourself running out of breadboard space. This is the main reason I chose an R2R DAC. I wonder if maybe instead of 255 comparators (just for 8 bits-
Comment: I use a different style? Is there another that may save space?
Comment: Just find an off the shelf SPI ADC or something... ?

R2R DAC in reverse


How can I communicate that a list item is expandable?

Question: I have a grid list made of cards. Each one of this cards contains 4 list item. If the user tap on the list item, the card is expanded in order to become a hero and to show the contents related to that list item. The icon must convey that the element is an interaction element, but it should also communicate that it is not simply a link or an accordion.
Comment: Can you add images of what you have?
Comment: In this moment I have only a wireframe of it, but I'm not sure I can share it, according to company policy. :(
Answer: I'd suggest trying to find an UI pattern that fits this purpose - so users are familiar with it, and will find it intuitive to click there to 'expand' and have more content.
In your case, perhaps 'card expand' according to Google guidelines (Material Design? is a possibility?
Cards: https://material.google.com/components/cards.html
Panels: https://material.google.com/components/expansion-panels.html
Or even the known '+' icon if it suits the functionality better.
https://material.google.com/motion/material-motion.html#
Comment: Yes, actually I'm adopting the material as UI pattern, and I'm using cards...  I was afraid in using arrows because in other parts of the applycations these opens detail panels. I think I will adopt a '+' icon ;)
Answer: I would suggest an icon combined with text. Maybe the word expand or show more etc, something along those lines as there might not be a stand alone icon for exactly what you are needing.


Will my young avocado tree grow up tall if the top burned off during it's first summer in the ground? Or is it's vertical growth stunted now...?

Question: About 2.5 years ago I planted a 4-5 foot avocado tree and didn't realize how truly delicate these things were. I planted it in January and it had a harsh summer with many branches burning off including what I'm assuming was the leader, or top sprout of the tree. It has since bounced back and is doing great after 2 years, but it doesn't appear to be growing much taller. Does this avocado tree still have the potential to grow up tall? Or did burning off the lead essentially stunt its vertical growth?
Answer: Trees in general, including the avocado, are programmed to replace the leader if it is lost. The issue that arises is that there may be multiple leaders emerge from the side shoot candidates. This causes the new tree to be somewhat shorter and sturdier than the original which had one strong leader. Pruning to favour one of the new leaders can restore the dominant upward growth.
If one single leader emerges and it still does not progress well then look for other reasons. Avocado is quite demanding on water resources and if grown in a dry location it won't make the expected growth.


Let X,Y be 2 r.v. with infinite expectations, are there possibilities where min(X,Y) have finite expectation?

Question: If it is impossible, what is the proof?
Answer: Take two positive iid Cauchy variates $Y_1,Y_2$ with common density
$$f(x)=\frac{2}{\pi}\frac{\mathbb I_{x>0}}{1+x^2}$$
and infinite expectation.
The minimum variate $\min(Y_1,Y_2)$ then has density
$$g(x)=\frac{8}{\pi^2}\frac{\pi/2-\arctan(x)}{1+x^2}\mathbb I_{x>0}$$
Since (by L'Hospital's rule)
$$\frac{\pi/2-\arctan(x)}{1+x^2} \equiv \frac{1}{x^3}$$
at infinity, the function $x\mapsto xg(x)$ is integrable. Hence, $\min(Y_1,Y_2)$ has a finite expectation actually equal to $\log(16)/\pi$.
More generally, in a regular Cauchy sample $X_1,\ldots,X_n$, with $n\ge 3$, every order statistic but the extremes $X_{(1)}$ and $X_{(n)}$ enjoys a (finite) expectation. (Furthermore, $X_{(1)}$ and $X_{(n)}$ both have infinite expectations, $-\infty$ and $+\infty$ resp., rather than no expectation.)
Comment: Very nice example. And $E[\min(Y_1,Y_2)] = log(16)/\pi$
Comment: Thanks. But do you mean only Xn does not enjoy finite expectation?
Answer: Let's find a general solution for independent variables $X$ and $Y$ having CDFs $F_X$ and $F_Y,$ respectively.  This will give us useful clues into what's going on, without the distraction of computing specific integrals.

Let $Z=\min(X,Y).$  Then, from basic axioms and definitions, we can work out that for any number $z,$
$$\eqalign{
F_Z(z) &= \Pr(Z\le z) = 1 - \Pr(Z > z) = 1 - \Pr(X \gt z, Y\gt z) \\&= 1 - (1-F_X(z))(1-F_Y(z)).}$$
For any CDF $F$, the expectation is
$$E_F = \int_{-\infty}^0 F(z)\mathrm{d}z + \int_{0}^\infty (1-F(z))\mathrm{d}z,$$
the sum of a negative part and a positive part.
Consequently, the question asks whether it's possible for $E_{F_Z}$ and $E_{F_Y}$ to be infinite but for $E_{F_Z}$ to be finite.  This requires both the negative and positive part of $E_{F_Z}$ to be finite.  Rather than analyzing this fully, it will suffice to study what happens to the positive parts: you can work out the analog for the negative parts.
In the worst case, then, the integrals $\int_0^\infty (1-F_X(z))\mathrm{d}z$ and  $\int_0^\infty (1-F_Y(z))\mathrm{d}z$ will diverge but we wonder whether the integral of the product
$$\int_0^\infty (1-F_X(z))(1-F_Y(z))\mathrm{d}z$$
diverges.  Clearly it cannot be any worse than the original two integrals, because since $0\le F(z)\le 1$ for all $z,$
$$\int_0^\infty (1-F_X(z))(1-F_Y(z))\mathrm{d}z \le \int_0^\infty (1-F_X(z))\mathrm{d}z \, \sup_{z\ge 0} (1-F_Y(z)) \le \int_0^\infty (1-F_X(z)).$$
This is sufficient insight to survey the landscape.  Suppose that as $z\to \infty,$ $1-F_X(z)$ is approximated by $z^{-p}$ for some positive power $p,$ and similarly $1-F_Y(z)$ is approximated by $z^{-q}$ for $q \gt 0.$  We write $1-F_X \sim O(Z^p)$ and $1-F_Y \sim O(Z^q).$  Then, when both $p$ and $q$ are less than $1,$ $E_{F_X}$ and $E_{F_Y}$ are infinite.

When $p+q \le 1,$  because $(1-F_X)(1-F_Y)\sim O(z^{p+q}),$ $E_{F_Z}=\infty.$
But when $p+q \gt 1,$ $E_{F_Z}$ is finite because $\int_0^t (1-F_Z(z))\mathrm{d}z$ is bounded above by $\int_0^1 (1-F_Z(z))\mathrm{d}z$ plus some multiple of $$\int_1^t z^{-(p+q)}\mathrm{d}z = \frac{1}{p+q-1}\left(1 - t^{-(p+q-1)}\right) \to \frac{1}{p+q-1} \lt \infty.$$

In other words, the infinite expectations of the positive parts of $X$ and $Y$ imply their survival functions $1-F_X$ and $1-F_Y$ approach their lower limit of $0$ only very slowly; but the product of those survival functions, which is the survival function of $Z,$ can approach $0$ sufficiently quickly to give $Z$ a finite expectation.
In short,

For $Z$ to have finite expectation, $(1-F_X)(1-F_Y)$ must converge to $0$ sufficiently rapidly at $+\infty.$  This can happen even when neither $1-F_X$ or $1-F_Y$ converge sufficiently rapidly.
Comment: As an illustration we can consider the Lomax distribution with
survival $S(x) = [1 + x / \beta]^{-\alpha}$ for $x > 0$ where $\beta
>0$ and $\alpha >0$ are the scale and shape parameters. The
expectation is finite for $\alpha > 1$.  If $X$ and $Y$ are
independent Lomax with the same scale $\beta >0$ and shapes
$\alpha_X$, $\alpha_Y$ we see that $\min(X,\,Y)$ is Lomax with scale
$\beta$ and shape $\alpha_X +\alpha_Y$.
Answer: Well, if you don't impose independance, yes.
Consider $Z \sim Cauchy$ and $B \sim Bernouilli(\frac{1}{2})$. Define $X$ and $Y$ by:
$$X = \left\{ \begin{array}[ccc]   0 0 & \text{if} & B = 0\\|Z| & \text{if} & B = 1\end{array}\right. $$
$$Y = \left\{ \begin{array}[ccc]  . |Z| & \text{if} & B = 0 \\0 & \text{if} & B = 1\end{array}\right. $$
Where $|.|$ denotes absolute value.  The $X$ and $Y$ have infinite expectation, but $\min(X, Y) = 0$ so $E(\min(X, Y)) = 0$.
For independent random variables, I don't know, and I would be interested in a result!
Comment: X and Y are not truly two dimensional case, though, I bet you can show the covariance matrix rank is 1. it's really just B you're proposing. i wouldnt count this as an example. basically X and Y are defined on the same exact event set, so it's the same variable in some sense. i's like saying I have X=Z and Y=1-Z.
Comment: Yes... this is a bit of a cheat example ^^. I think covariance matrix is undefined on this example, but indeed the support of $(X, Y)$ is of null measure in $\mathbb{R}^2$.
Having non totally linked random variables isn't hard though, with same setup, draw $X$ and $Y$ from independent uniform distribution if $B = 0 $ and from independant absolute value Cauchy if $B = 1$.
Comment: can you show in this case that min is indeed finite?
Comment: Well, yes, since it is always smaller than one (since there is always one of $X$ or $Y$ simulated from uniform.
Comment: In my 2-previous comment, I made a mistake, I meant than $X\sim\mathcal{U}([0, 1])$ if $B= 0$ and $Y\sim\mathcal{U}([0, 1])$ if $B = 1$, and same for the Cauchy part of the distribution, such that for any value of $B$, one of the two variables has been generated  by a $\mathcal{U}([0, 1]).
Answer: This answer is not as general as Whuber's answer, and relates to identical distributed X and Y, but I believe that it is a good addition because it gives some different intuition. The advantage of this approach is that it easily generalizes to different order statistics and to different moments or other functions $T(X)$. Also when the quantile function is known then the possibility or impossibility of 'making a statistic finite' by using an order statistic is easily seen by the type of singularity at 0 and 1.
A quick intuitive view of the possibility that an order statistic might have finite finite expectation even when the underlying variable does not can be done via the quantile function.
We can view the moments of a distribution as the moments of the quantile function:
https://stats.stackexchange.com/a/365385/164061
$$E(T(x)) = \int_{0}^1 T(Q(q)) dq \\$$
Say we wish to compute the first moment then $T(x) = x$. In the image below this corresponds to the area between F and the vertical line at $x=0$ (where the area on the left side may count as negative when $T(x)<0$).

The curves in the image show how much each quantile contributes in the computation. If the curve $T(Q(F))$ goes sufficiently fast enough to infinity when F approaches zero or one, then the area can be infinite.

Now, for an order statistic the integral over the quantiles $dq$ changes somewhat. For the normal variable each quantile has equal probability. For an order distribution this is beta distributed. So the integral becomes for a sample of size $n$ and using the minimum:
$$E(T(x_{(n)})) = n! \int_{0}^1 (1-q)^{n-1} T(Q(q)) dq \\$$
This term $(1-q)^{n-1}$ might be able to make a function that initially integrated to infinity because it had a pole of order 1 or higher (it's behaviour near $q=1$ was like $T(Q(q)) \sim (1-q)^{-a}$ with $a>1$), is now able to integrate to a finite value.

Example: the sample mean of the median of a sample taken from a Cauchy distributed variable is now finite because the poles of 1st order are removed. That is, $q^a(1-q)^b \tan(\pi (q-0.5))$ is finite for $a\geq 1$ and $b\geq 1$. (this relates to the more general statement of Xi'an about order statistics in relation to a Cauchy variable)
Further: When the quantile function has an essential singularity, for example $Q(p) = e^{1/(1-p)} - e$ then the sample minimum remains with infinite or undefined moments no matter the size of the sample (I just made up that quantile function as example, it relates to $f(x) = \frac{1}{(x+a)\log(x+a)^2}$, I am not sure whether there are more well known distributions that have an essential singularity in the quantile function).
Comment: (+1) very nice point of using the quantile transform. I would suggest writing the last integral equation as$$\mathbb E[T(X_{(n)})]=n! \int_{0}^1 (1-q)^{n-1} T(Q(q)) \text{d}q$$to make things clearer.
Answer: It's the case with almost any distribution because the expectation on a subset grows usually much slower than the subset. Let's look at the expectation on a subset for a variable $z$ with PDF $f(z)$:
$$E_x[z]=\int_{-\infty}^xzf(z)dz$$
Let's look at the rate of growth of this exepctation:
$$\frac d {dx}E_x[z]=xf(x)$$
So the expectation on a subset grows much slower than $x$, the boundary of a subset. The implication is that although for a distribution with no moments such as modulus of Cauchy $|z|$ the expectation is infinite $E_\infty[|z|]=\infty$, its growth with upper boundary of the subset slows down a lot with large $z$. In fact for this case $E_x[z]\approx 1/x$.
Why is this relevant? Here's why. Look at the expectation of $E[x|x<y]$ where both $x,y$ are from the same distribution with density $f(.)$ that has infinite mean:
let's look at the expectation of the minimum:
$$E[x|x<y]=\int_{-\infty}^\infty dyf(y)\int_{-\infty}^{y}dxf(x)\times x\\
=\int_{-\infty}^\infty dy f(y)E_y[x]
$$
Since $E_y[x]$ grows much slower than $y$, this integral most likely will be finite. It is certainly finite for modulus of Cauchy $|x|$ and is equal to $\ln 4/\pi$:

$E_x[|z|]=\int_0^x\frac 2 \pi\frac {z}{1+z^2}dz=\int_0^x\frac 1 \pi\frac {1}{1+z^2}dz^2=\frac 1 \pi \ln(1+z^2)|_0^x=\frac{\ln(1+x^2)}{\pi}$ - here already we see how the expectation on subset slowed down from $x$ to $\ln x$.
$E[x|x<y]=\int_{0}^\infty \frac 2 \pi\frac 1 {1+x^2}\frac{\ln(1+x^2)}{\pi}dx
=\frac 1 \pi \ln 4
$

You can apply this analysis to the minimum function trivially.
Comment: Since $\mathbb E[\min(|X_1|,|X_2|)]=\log(4^2)/π$, I was puzzled by the discrepancy. I think it is because you forgot the normalising $\mathbb P(x<y)=1/2$ in all conditionings and in particular in the conditional expectations.


Mathematical toys?

Question: Anybody know of "serious" mathematical ornaments or toys like the Gömböc,
etc?
Already have a rubix and abacus (that's more of a tool though).
Comment: You probably mean "lax" in the above comment (somewhat Ironic since in your question statement it probably should be "Rubik's" cube).
Comment: Define "serious."
Comment: I was being lack there, perhaps I should define what I do want by what I don't want; placing the correct shape in the hole, children games and so on.
Answer: For when the Möbius strip is too pedestrian, the good people at Acme Co. claim their Klein bottles are the "finest closed, non-orientable, boundary-free manifolds sold anywhere in our three spatial dimensions."
Comment: His book the Cuckoo's Egg is a lot of fun, too.
Answer: On Shapeways, you can find a variety of mathematical ornaments.
My favorites are the differential geometric surfaces designed by Bachman.  I also like Bathsheba's designs as well.

(Sorry the image is so large.  Is there a way to reduce the size?)
Answer: I have a Rattleback at my desk.  Fun to fiddle with while thinking.
Answer: The Rubik cube. ${}{}{}{}{}{}{}$
Comment: Oh yeah obviously I have one of those - I have some with more than 6 faces also, though in the end it's a tougher algorithm. Very nice puzzles though.
Answer: Spirograph from Hasbro. You can make lots of famous mathematical curves with its pieces: epicycloids, hypocycloids, etc. MathWorld has an article on some of these curves.
Comment: I love the Spirograph; +1 of course.
Answer: Zometool is a construction kit which has 2-, 3-, and 5-fold symmetry, which is great for building (3D projections of) the 120-cell, or just for playing around.
Comment: @Adam:  Seeing this, I thought of K'nex.  Their website doesn't have any info on what symmetries are supported on the home page.  I grew up with tinker toys.
Answer: Wikipedia has a section on mechanical puzzle.
As for myself, my fascination with algebraic topology began with metal link puzzles or hanayama.
Of course, Tower of Hanoi is a classic.
Of interest may be the reference: Adventures in Group Theory: Rubik's Cube, Merlin's Machine, and Other Mathematical Toys by David Joyner. Book description in Amazon.
Answer: While it may be a 'children's toy', the Switch Pitch works remarkably well as an object of mathematical sculpture; it's fundamentally based on the fact that the vertices of a regular cube are also the vertices of two (interlocked) regular tetrahedra (if your cube is $\{0,1\}^3$, take the vertices with $i+j+k$ respectively odd or even).  It helps that people can't help but fiddle with it; it's been a perfect hand-fidgetting toy for me.
Answer: The Oloid is fun to touch, to watch and understand.
Answer: Maybe a Tippe Top.
Answer: Love zometool [1]
[1]: http://www.zometool.com/  for geometry, platonic and archimedean solids, among others/
Answer: Double pendulum.
Answer: http://tavernpuzzles.stores.yahoo.net/puzzle.html http://ep.yimg.com/ca/I/tavernpuzzles_2188_4561747
Goal: Remove the big ring
http://tavernpuzzles.stores.yahoo.net/puzzle.html
Answer: I think there are 2 different toy devices that mimic a Gray code.
One can be seen at http://mypuzzlecollection.blogspot.com/2011/12/brain.html.
The other is named "Spin Out".
Comment: Also the Towers of Hanoi.
Answer: Check Montessori mathematical materials like the binomial cube just google it
Answer: Sudoku and all other logic trainers would also fit.
Answer: Origami to fold shapes to find surface area of 3 dimensional shapes.  Wooden blocks.  The Game of 24.  Math Jeopardy.  Bucky balls.  Sudoku.  Computer games with rotations and other types of transformations.
Answer: In a blatant reference to my own creative work, I submit for your consideration the mathematical artwork presented on my Shapeways Shop at this address: https://www.shapeways.com/shops/Feingold_Math_Art
But there are a huge number of other artists whose work can also be found in other shops there.

Mathematical toys?


Jittery console after booting into Debian?

Question: This is a weird problem. I think the main thing that's stopping me from fixing it myself is that I can't Google it because I have no idea what terminology I should use.
So I installed Debian today as a first Linux OS (not counting Ubuntu - but I didn't use it extensively and wasn't familiar with terminal commands anyways).
After installation, I found the system resolution to be 800x600. My monitor supports up to a 1920x1080 resolution, so I decided to try and find out how to increase the resolution (because the preferences only had 640x480 and 800x600...)
So the first thing I find is cvt 1920 1080 and then xrand or something. That winds up not working. I troubleshoot some more and decide that I need to find NVIDIA drivers for my computer.
After looking for those, I find a very informative page on installing NVIDIA drivers. Turns out there are two ways: The Debian way and the NVIDIA way. I end up doing the following:

downloading amd64 version of NVIDIA Graphics Drivers (latest 71xx version)
trying to run the .run file
finding out you need to use sudo sh
I try sudo sh NVIDIASTUFFHERE(FORGOT FILENAME BECAUSE DEBIAN WON'T BOOT)
find out I need to stop gdm from running
try sudo service lightdm stop
try sudo service gdm stop
after browsing for a while, find out to use file path and gdm3
sudo /etc/init.d/gdm3 stop ends up working
now sudo sh NVIDIASTUFFHERE works, but I need to switch gcc from 4.4 to 4.3
find out I need to use update-alternatives to switch it
find out I need to use export to switch it
after using both, I can now finally run the NVIDIA drivers installer!

Okay, so I've finally installed the drivers. Now I have no idea what to do with them. I find out I should make an xorg.conf file in /etc/X11/. I make it, and it says something like driver: "NVIDIA" and not much else (can't remember because, again, I can't pull it up to look at it... I think it was about 4 or 5 lines long.) I do some more Googling (I try to solve most everything by Googling it) and find that I should use some invoke-rc.d something something gdm3 or something command to fix it. The reason I don't remember the exact command for this is what happened after...
Something crashes. Debian shows a screen with a jittery console on it. I do some research and find that another page told me to use different commands after installing the driver, but it was too late now. After rebooting Debian with various commands that I had to use earlier for troubleshooting, nothing works.
(for reference, the commands I tried booting with were xforcevesa and i915.modeset=1. Also, Debian won't boot (stops after a little console stuff to show absolutely no display) UNLESS I add nomodeset in the grub console you get after pressing e on an OS.
So... Now that I know how to properly use these NVIDIA drivers... how do I get out of this thing? To describe the symptoms of the jittery console:
Debian shows a Loading, please wait.... After this, it says some other stuff, ending with Starting Common Unix something-or-other. Then, I get a console. It's not a normal console. It won't let me type in it unless I continually spam the key. Won't let me backspace anything. There is no prompt. It constantly switches between showing the key(s) I've typed and showing a blank console (hence the term 'jittery'... it's hard to describe without seeing it).
I've looked it up on Google but can't seem to find a response that responds to the exact question I have. I think the problem was caused by either the xorg.conf or the invoke-rc.d command, but I'm leaning towards the invoke-rc.d, because I got the jittery console immediately after and booted right back into it no matter what I tried.
I hate to come here with a problem without good details, but I tried my best (couldn't look a lot of things up because they're on the system and I can't boot into it). If you need the info, I'm running Debian 6.0.7 ('Squeeze'?) alongside Windows 7 (dual booting)  on an (obviously) NVIDIA graphics card. If you need any other info, please just ask and I'll do my best to provide it.
Comment: If you press  or , can you get a console? Can you ssh into the box? Is there a serial port that you can connect a null modem cable to?
Comment:  doesn't work for getting consoles. Don't quite know how to ssh into the box, and a serial port? No idea what that is. =/ However, just so you know, it was previously an All-In-One computer (computer is literally CONNECTED to the monitor, there is no separation)
Answer: First you have to boot with
init=/bin/bash
in order to have a "real" terminal, it's like a rescue mode, witch let you edit your files.
I recommend removing your xorg.conf file and optionnaly: update-rc.d gdm3 remove


What questions to prepare for PhD defense?

Question: I will soon defend my PhD in social science in Sweden. I want to ask what questions the evaluation committee will ask me during the defense?
If they ask me some questions outside my thesis, what shall I do? Is it enough only know well my own research?
What quality I need to successfully defend my PhD?
Comment: Have you not gone to other people's defenses before? Have you asked your advisor?
Comment: Whatever field you study and whatever type of presentation you give, always be prepared for questions asking you why you made certain decisions. It won't hurt preparing for them and it might actually improve your presentation if you hadn't thought about it before.
Comment: Obligatory XKCD: https://xkcd.com/1403/
Comment: I don't recall ever hearing any restrictions on what I can ask in a thesis defense. Ordinarily, I ask about things in the thesis, prerequisites for things in the thesis, and things that the candidate happens to mention during the defense. I could, in principle, ask a completely off-topic question, to which the candidate might well reply "I have no idea"; presumably, such an answer wouldn't damage the outcome of the defense (unless the other 4 examiners agree with my craziness).
Comment: I was asked "who is Maud Menten?" (see 1910's at http://famouscanadianwomen.com/famous%20firsts/medical%20professionals.htm) Since I used the Michaelis-Menten equation in my work, it was borderline relevant. Luckily there is a plaque to her on the U of T campus, so I knew both the equation half of the answer and the trivia question half. That was the only question that examiner asked. Seriously, know your thesis well and ask your supervisor if you can expect anything unusual, and you'll be ok. They don't generally let you defend if they don't think you're ready.
Comment: @VladimirF Yes, but that sounds like a horrific idea.
Comment: @xLeitix At some universities, only professional staff is welcome at PhD defences.
Comment: @KateGregory In some countries (at least in mine) they cannot just not let somebody defend his thesis just because they do not want. You have a legal right to try to defend your thesis even if the reviews are bad.
Answer: Generally speaking, PhD defenses come in two flavors, and it is not possible to say a priori which one yours will fall into:

A real thesis "defense" focuses on the thesis, and all questions will relate to the scope of the research work. In this case, knowing your own work and its context well enough should be sufficient, but it is of course possible that somebody asks you why you used method A rather than B. In this case, saying that you don't know B may not fly as an answer. However, you should not get a completely disconnected question just to test your general subject area knowledge.
A "Rigorosum" (dict.leo translated this for me to "doctoral viva", no idea if this is a well-known term) is a general final exam for a doctoral candidate. Typically, this will also include questions about the disseration, but anybody in the exam commission is free to ask about other topics in the field as well. Typically, the questions are getting "easier" (more high-level) the farther they are away from the topic of the dissertation. The claim here is that a fresh PhD should have both, depth and breadth in her/his knowledge.

There are a number of ways to figure out which class your defense will fall into:

Attend other defenses. Typically, PhD defenses are public, and it is highly recommended that any PhD candidate should visit a few before her/his own, to get to know the procedure and get a feel for what the defense talk is supposed to look like.
Ask your advisor. The advisor should obviously know what the requirements of the defense are, exactly.
Look it up in the programme description. Usually, the programme description will contain exam regulations for the defense, and this should describe the exam procedure and who is supposed to ask what kind of questions. This approach has two dangers: (1) you may misunderstand what the exam regulations are saying - as they are more legalese text, you may misunderstand the gist of it, and (2) the actual exam may happen differently than specified - there is no telling whether the exam regulation exactly captures the real spirit of the defense. Hence, you should really also talk to your advisor and/or attend other defenses as well.
Comment: Typically, there's a non-public part of the defense after the public part where the general public is asked to leave and the committee can grill the candidate in private. That's where the interesting/hard/potentially embarrassing questions are likely to come. This is harder to prepare for and benefits from asking your advisor and recent other students for guidance.
Comment: @BillBarth Ok, I was not aware of that. In all universities that I was aware of, everything *needs to be* public to have traceability of decisions.
Comment: In addition to that, vivas in the UK are typically behind closed doors in their entirety - only two(ish) examiners and the candidate, with even the advisor being absent.
Comment: "Viva" (short for *viva voce*) is the term used in the UK (and some other countries?), I'm not sure if use of this term corresponds to your two categories or not. At my UK university you are expected to answer questions generally on your field as well as your thesis.
Comment: good answer. i would like to add that the OP should look into their supervisor's reviews of the thesis. in some countries/unis these are provided beforehand. they contain the main criticism and these will come up also in the defense. the defense talk itself should already address them.
Answer: Some types of questions that often come up:

Questions about some detail of your work.  The point of such questions is often not so much the correctness of this small part of your dissertation, but rather to get you to demonstrate your ability to explain what you've done.  This also helps to balance out the presentation, which typically covered the whole thesis in much less detail.  For example, in mathematics you might be asked to go over the proof of one of your theorems in detail.  Since you've spent more time working on these details than any of the examiners, and assuming that the examiner hasn't spotted a substantial error, you should be in a good position to answer such a question.  Don't panic and assume that you've made some huge mistake, but rather go through the material carefully and convince the examiner that you're correct.
What are the broader implications of your work?  This is actually a hard question for most students to answer because they've been so focused on the details of their thesis that they may not have taken time to see how it fits into the broader picture of progress in their discipline.  This will also be an important question when you eventually interview for faculty positions.
Can this method be applied to some other problem Y?  You may be asked how the techniques used in your dissertation could be applied to a different problem.  If the answer is that the technique doesn't extend in that direction, then you should be prepared to explain why not.
Questions about what exactly is new in your work.  You should have been extremely careful in writing your dissertation to properly cite earlier work and distinguish your new contributions from that earlier work.  If this isn't clear to the examiners, you may be asked to clarify.
Answer: I attended about a dozen PhD defenses and recently defended my own PhD. Based on my (very limited) experiences, questions can be roughly categorized into two types:

Knowledge: the first set of questions or statements are usually to test your knowledge on your topic, the related work and whatever you have written down in your thesis and/or papers. If you have done all the work, these are mostly fairly easy to answer and are your way to demonstrate the awesome work you have done. These questions are to clarify, justify and frame your work related to others, in order to get a solid understanding of your contribution.
Examples:

Can you explain what you mean with #concept you introduce#?
Why did you categorize or describe #your concept# in this way?
I believe #your topic# relates to #other guys theory# in such a way, which introduces an interesting contradiction. Can you comment or elaborate on this?
What is the main limitation of your work, and how could you address it?

Reasoning: committee members may also ask provocative or even harsh questions to see how strong you believe in your work but also whether you can transcend your topic and reason on a higher level. These questions or statements can be directly related to your topic but can also be more general. These types of questions are usually given to see how well the candidate performs when put under pressure and when they are questioned about things beyond their thesis. These can be interpreted as "nasty" questions, but remember that you can turn the questions around to your advantage. Examples:

Why do you believe this is science? What is science?
You spend #x# years researching this? Why did you choose the topic and why should we and the community care about it?
I don't see the contribution in your work, can you explain?
Why do you think you deserve a PhD?
Why did you choose this specific application domain?

Again, this is based on my personal limited experience, but it applied to my PhD defense as well.
Answer: You do not have much influence on the questions from the committee. If your PhD studies were more or less normal and you got that far,  everyone wants you to succeed. They will not ask anything incredible (if they are relatively normal as well).
As for the public questions,  my experiences are :

the friends you gave questions to.  You have to choose the ones who have good reflexes to jump up and down when time for public questions come. You also have to train the "what a surprising question look"
the odd colleague who decided to ask a question about something related to your field,  but far enough for you to have no idea. You sweat a lot, visualize him hanging on a tree and hope for the best. Best is to answer whatever you know on the subject and everyone acts happy. If he persists then you ask him what is his view on the subject so that he sits down ashamed mumbling "I have no idea"
finally the 173 years old professor who absolutely wants you to discuss his article from 1952. You thank for the question and talk about the article from 2012 someone wrote on a related subject.

Good luck.
(events described above actually happened to me in the course of my 2 hours defence)
Comment: Even though I will not ever have to go though a PhD defense anymore, it would have been great to understand the downvotes.


How can I improve or replace my programmer art?

Question: Say I'm a programmer who has done his own sprites or 3d models which would fall into programmer-ish kind of art. What steps can I take in order to improve or replace my own art?
Comment: @Ricket: Yeah... that's exactly why I created this question. ;) Besides, some programmers do draw *believe it or not*. So any resource on how to get any better at it would be helpful.
Comment: Almost-exact duplicate: http://gamedev.stackexchange.com/questions/2326/graphics-for-non-graphics-designers except Tetrad declared it to be a different question when I suggested a title change. Thus this question, I guess.
Answer: http://opengameart.org/ its a nice resource too.
Answer: 1) If you want to improve try putting up your work on specialized sites like http://www.polycount.com/forum/
2) If you don't have time or insert reason here go to recruiting sites, here are a few to get you started:
http://forum.unity3d.com/viewforum.php?f=11
http://www.polycount.com/forum/forumdisplay.php?f=44
http://www.moddb.com/forum/board/recruiting-resumes
Answer: The best way of having your programmer art replaced by real art is to carry on making a great game.
Pimp your game as often as you can - concentrate of game mechanics first - then I am sure that you'll attract some artist types - maybe even for free (join the team).
This approach is probably the only one if you're short of cash, and/or want to stay free.
Programmers art could make sure that you concentrate on the most important aspect of your game: the game itself.
There are of course places where you can grab models and art under an open license, but I would just carry on making a game if I were you.
Don't bother spending too much time trying to learn how to be an artist yourself.
That skill takes years..
Answer: You could try making more art. The saying 'practice makes perfect' is probably applicable here.
Or, you could advertise on a site such as Gamedev's Help Wanted Forum for an artist, saying that you've created such and such a game, with your programmer art, and looking for a improvment to the graphical quality.
The other way is to get free images, textures, and models from many sites on the internet. However, these aren't necessarily what you want. Option 2 is probably the best way, unless it's more of a learning project (not for release).
Answer: I would recommend you to search a skinner and/or 2D Artist who is skilled and can create that kind of art. This is a good forum i remember, where like just skilled artists are grouped :)
You could search at Deviantart too, but there it's imo more complicated.
Or you try learning it in a professional way, but that is exhausting...
Answer: Go to forums. Artists need you as much as you need them.
Comment: Which means he needs to convince the artists that they need what he can do.
Not an easy task. :)
Comment: I guess I have had the opposite experience.