Clear form fields on firefox

Question: Firefox stubbornly persists in filling out a form for me. I've already tried clearing the cookies and form history.
Any ideas as to how to keep the form fields blank?
Comment: Tools -> Options -> Security. Try checking saved stuff.
Answer: If you open Firefox/Options/Privacy there should be an option (check box) that allows you to "Remember Search and Form History" if you uncheck that box firefox won't retain and form data.
You could also use inbuilt privacy cleaner or something like CCleaner to remove this data periodically.
Answer: You should be able to delete individual entries by using the up/down keys to highlight them and hitting shift+delete.
See "Delete Selected Autocomplete Entry": http://support.mozilla.com/en-us/kb/keyboard+shortcuts

Clear form fields on firefox


Options for making rocket fuel using the Moon's natural resources

Question: Based on what is known about the chemistry of the lunar surface through remote sensing and surface exploration, what raw ingredients are likely to be available that can be used to make rocket fuel?
Comment: If there is water ice in deep craters close to the Moon poles, liquid hydrogen and oxygen may be generated from water needing a lot of energy. But to get a storable hypergolic fuel like hydrazin and nitrogentetroxid you need nitrogen too.
Answer: There are a number of rocket fuels that can be made from moon rock, discussed in some depth in  this answer  and the linked papers. Aluminium and liquid oxygen seems to be perhaps the leading contender. None is as good in various respects as "normal" fuels like kerosene and liquid oxygen, and there are some engineering problems, but they are possible.
There is recent evidence of water (probably in the form of slightly less dessicated, but still thoroughly frozen rocks) at the South pole of the moon, where there are craters in permanent shadow. If that can be extracted, then liquid hydrogen and liquid oxygen can be prepared.
Answer: The lunar regolith contains over 40 weight % of oxygen, but the rest of metals and silicon are not well suited to make a fuel. There is very, very little carbon or hydrogen, less than 1 %. Without finding water it is not possible to prepare a good fuel.

The ubiquity and abundance of oxygen in rocks and soils in space
(42–45% by weight in lunar samples) incite scientists and engineers to
devise the most efficient techniques to extract it.

Table source.
Comment: Liberating the moon's oxygen: fly some quantity of hydrogen to the moon, [reduce the iron-oxides of the regolith](https://en.wikipedia.org/wiki/Direct_reduced_iron), put the resulting water vapour through a condenser and an electrolysis cell. This way, you run the hydrogen in a circle, and produce oxygen from lunar soil. However, you need plenty of energy, and some equippment.
Comment: @DohnJoe Hot iron reduces water vapor to hydrogen, that is how hydrogen was discovered by Lavoisier. But does hydrogen reduce hot iron-oxides to iron without splitting the resulting water again?
Comment: If stream hot hydrogen through a bed of hot iron oxides, a stream of water vapour will leave your reaction vessel. Of course you need to strip the vapour from the hydrogen gas before the gas enters the reactor again. Iron oxides can be reduced by hydrogen, or carbon monoxide, when it is still solid, that's why this process is called direct reduction of iron. Thermolysis of water happens at very high temperatures.
Answer: Aluminum manufactured into nano-sized particles can be mixed with water ice to make a fuel called ALICE.  NASA has already flown a small rocket using ALICE.
ALICE fuel Wikipedia Entry
Another option is to use pure water with a nuclear engine heating it to extremely high temperature.  This would work for point-to-point hops or trips from lunar surface to orbit and back.  This has a lower ISP than a liquid oxygen/hydrogen fuel, but avoids the need for cryogenic processing, storage and transport on the moon.
Comment: At that point, it's less "rocket fuel" and more "reaction mass"... pedantic, I know


In snowboard/ski cross, how are jerseys determined in the rounds?

Question: The first one is depending on the qualification times. That I know, but for the rounds after does it still depends on the qualifing time or is it determined by the position in the last round?
Answer: As written in the fIS rulebook at article 2706 pairings for the finals will be according to the following:

So thi is the rank in the next round:

winner of heat#1
winner of heat#2
to 8. winner of other heat
from 9th to 16th the secon for each heat

Each starting position is identified by colour and/or number.
Colours are determined by qualification ranking (time) in each heat:

1st ranked Qualification competitor – Red
2nd ranked Qualification competitor – Green
3rd ranked Qualification competitor – Blue
4th ranked Qualification competitor – Yellow
(5th ranked Qualification competitor - White)
(6th ranked Qualification competitor - Black)

Furthermore first ranked competitor from the qualifications can choose their lane, with the second fastest the next lane and so on
Comment: Ok thanks, that is how they are spread for the first round. My question asks for all the subsequent rounds.
Comment: @Fredy31 the answer is about the subsequent rounds after the qualification
Comment: Ok you edited. So someone that falls during qualifs will always have to pick last?
Comment: @Fredy31 this is another question, please open a new ticket on it


Extrinsic Calibration Target Depth Camera

Question: What's a good calibration object for the extrinsic calibration (rotation + translation) of a depth camera (no color sensor, only depth)? With RGB, people seem to typically use chessboard pattern or some kind of markers. Is there something similar that would work without RGB?
Answer: You can use a 3d Marker, e.g. a cube or a another arrangement of three planes. Finding these planes in the Pointcloud/Depth Image is not hard and provides a 6D Pose (if you can distinguish the planes which can be done by using non-90-deg angles).
If you also add visual markers (e.g. checkerboard pattern) to the planes, you can first use a 2d Camera to measure the relative poses of the planes.


How to keep frozen French fries crispy?

Question: There are a lot of frozen French fry recipes on Google and YouTube, but none stay crispy after defrost. I have tried many. After 2-4 month they become soft and pale. I doubt there are some chemicals which can keep their taste and crispy texture. Such as potatopro or McCain supplier.
Any suggestions?
Answer: Most likely, your issue is that your fries don't freeze quickly enough!
First of all, potatoes are VERY tricky for freezing anyway: their cell-structure takes REALLY badly to freezing, making them change texture and sometimes taste a lot.
The problem is reduced, but not removed, by cooking them first, but even then, they tend to react badly.
Now, what do commercial fries have that you don't? They can actually do shock-freezing! This means they can freeze their fries REALLY quickly, which highly reduces the damage to the cells. So, sadly your best shot may be: buy some dry ice to use for freezing your fries.
Comment: Thanks a lot Layna. Then I must plan to buy a good refrigerator. Can you suggest some brand? Can I freeze the fries or potato after mixing  some testy ingredients, such as paprika?
Comment: @user65822 ensure your current refrigerator has one of its shelves empty , put a piece of tin foil straight onto the freezing elements throw it straight on there while still lukewarm.
Comment: @Fabby : while still lukewarm?  Typically when you want to avoid ice crystals, you shill it down to fridge temp, *then* freeze it.  You can put a sheet pan in the freezer ahead of time, so that has some thermal mass to soak up the heat.  (but the dry ice suggestion might be better ... or liquid nitrogen, if you want to spend way too much money on this project)
Comment: I single-fry them first, then fast-freeze @Joe, thus lukewarm thus smaller ice crystals as they don't have time to grow. (works for me!)
Answer: To my experience I throw them in the fryer right out the freezer (with oil at 350F)
they get that golden look and crispy texture. Wouldn't recommend do it at home with a pot and oil unless you have one of those little fryers

How to keep frozen French fries crispy?


why are non singular curves used in elliptic curve cryptography?

Question: It is not possible to draw  tangent at all the points of a singular curve. What is the specialty of this and how it is related to cryptography and elliptic discriminant?
Comment: In ECC we use elliptic curves, where by definition are non-singular. But you can use varieties in cryptography. For instance, you can use Jacobian varieties, because they form a group where dlog is hard. If it occurs non-singular curves to form a group, whee dlog is hard, then they will also used such curves.
Answer: Not-so-useful answer: An elliptic curve is by definition a non-singular curve. Therefore by definition we use non-singular curves in elliptic-curve cryptography.
Why not use singular curves? It turns out that the group structure on those curves is isomorphic to the multiplicative group of a (quadratic extension of) a field. Therefore the discrete logarithm problem is not harder than of that in a finite field, so there is little reason to use the curve in the first place.
The discriminant characterizes all curves which are non-singular. In other words, the curves that are non-singular are exactly those for which the discriminant $\Delta$ is non-zero.


Convert MTEF to MathML

Question: I use SDK DSSCI (MathType) for MTEF -> MML formula conversion, in WEB C# application.
Conversion is well performed from DLL function, with string input (code MTEF) and string output (code MathML), but I see that MathType EXE is ever runned and closed from my application.
If MathType is NOT installed, the function DOESN'T work. Is it possible to obtain conversion, only with deployed SDK DLL (MTSDKDN.dll and MT6.dll), without installing MathType on the WEB server?
Answer: The conversion from MTEF to MathML is actually done by MathType itself, so no. (Sorry for the very delayed response. This one showed up in my feeds only this morning.)
Bob Mathews, Design Science

Convert MTEF to MathML


BoA Closed my Accounts and Froze my Funds. How can I get money back besides cashier's check?

Question: Earlier this week I had tried to buy food with my debit card but the transaction was declined. I immediately contacted my bank (BoA) and was told there was a note left with a number to call. I called the number and it was a voicemail from the account closures department. I had left a message to the number that way they could call me the next day. I had gone to one of the branches to get more information about why my accounts were being closed and told to contact the same number left on the note. The next day the account closures department called and told me that I would be receiving a letter in the mail that my accounts would be closed the next week and was told that a cashier's check would be issued next week as well and to expect it in the mail around ten business days. When I asked why they were being closed I was just told that it was a business decision and couldn't give me any further details. In the two years I banked with BoA I never had an overdraft or any negative marks on my account so the only thing that would stick out was a check that I deposited for $26k that my mom left me after she passed.
As of now I have about $32k total that is just sitting and cannot do anything with it and am frustrated because that's nearly all my money and cannot wait for almost two or three weeks to get a check in the mail when I have bills and other things to pay for within that time. I also can't transfer anything to my other bank or any other bank because of the holds. Are there any other alternatives to receive my money sooner or will I have to just wait it out?
Comment: I am sorry for your loss, but could you tell us a few details about the check "that my mom left me"? Was this a check handed to you by her on her deathbed (and was it post-dated?), or was it a signed check found in her checkbook or other papers after her death, or was it a check issued to you by the executor of her estate? The reason for asking is that if the check that you deposited into your account reached your mom's bank _after_ your mom's bank had been notified about her death, your mom's bank may have refused to pay it (and especially so for a check bearing a date after her death).
Comment: Note that the "business decision" may well be entirely unrelated to you.  It's not impossible that they closed the account for another reason - such as stopping doing business in your area.
Comment: Clarification: Are they saying YOUR account is being closed, or your mother's? Maybe they are just putting a hold on her check to you if they got notice that she was deceased until the executor takes over the account?
Comment: also account or accounts? - You use both wording.
Comment: No these are my own personal checking and savings accounts. I live in Texas and my mom had a college fund plan made for me back when I was a kid. Because I went to college on scholarship I didn't need to use the money to pay for school so after I graduated I requested.
Comment: No these are my own personal checking and savings accounts. My mom has nothing to do with this she died before any of this happened I mentioned her because I inherited the 26k(college funds through Texas Guaranteed Tuition Plan...my mom set up college funds for me when I was younger). I received that money as a check and deposited it in my savings account but becuase I never made a deposit that large the bank might have thought it was too large of a deposit to just not look at. I have my both my checking and savings accounts frozen as of now.
Answer: I'd suggest you contact the Office of the Controller of Currency, who regulates BOA and file a complaint. This whole deal seems shady.
According to the OCC FAQ, the fact that they closed the account is in their prerogative. However, I would think they are obligated to quickly return your funds, but can't find anything specific to that.
The banks are very sensitive to having complaints filed against them, so if nothing else this may encourage them to be more helpful, even if your complaint isn't actionable.
OCC Complaint Process.
This topic on how long a bank can hold a large deposit before making funds available may also be helpful.
Comment: I deposited the check back on November 10th and had most of the funds on hold until the 19th then the check cleared. What I'm saying is that that would be the only thing that would stick out on my banking activity to whoever looks over my accounts at BoA but my accounts were frozen this week on Monday the 9th.


How to eliminate advantages gained from the seating position of inferior players?

Question: In many games, such as Liar's Dice or On The Underground, there is an advantage to be had by sitting immediately after (in the turn order) the player who is least experienced or just plain bad at the game. Are there any widely applicable ideas for resolving this problem? Or, is there some house rule or variant that improves this aspect of a particular game?
Comment: The same advantage happens in Puerto Rico, you always want the new guy on your right (and you want the 'best' player to your left).
Comment: As long as you take the time to *explain* as much as possible beforehand, that will go a long way in my opinion.  One of my groups will explain the game in almost painful detail before starting, and the other will just throw me into the game and constantly say, "Oh, by the way, we forgot to tell you this" *after* I've done something stupid.  Guess which group I prefer?
Comment: In Dominion, there are really only two cards that depend on the person directly next to you.  Those cards are Possession (person to your left being good is favorable) and Contraband (person on your left being bad is favorable).  Of course, one thing to explain to bad players if THEY have Contraband is that it needs to be the very first treasure they play, so that the other person doesn't know how many coins you have.
Answer: I think you can't have a serious, cutthroat game with a wide range of skills, so relax. Gently coach the new players, but no more than they're willing to receive. Play a couple of dummy rounds for the new players and then restart if needed.
If you're really serious, you can investigate ways to handicap the game, but that's really hard to do without ruining the balance of most games.
Answer: Assign seats randomly.  Card draw, dice roll, etc.
A part of strategy in games is knowing the situation you are in and adjusting your game play.  If you get the unlucky draw of being to the right of this person, you'll need to adjust your strategy knowing the person to your left may not make the play an experienced player may make.  Many times I make a play I normally wouldn't make when I sit the right of an inexperienced player if I cannot afford for the person to the left of the player to make specific play.
So in my opinion situational awareness should dictate your strategy.
After every game we play, we re-assign seats randomly.
Answer: Board game skill definitely transfers from game to game. If you really don't want to play Puerto Rico with an unskilled player because the person to their left will have an advantage, then play different games with them that do not have this problem.
For example. Power Grid has turn order that changes based on how many cities a player has. Of course good players will purposefully hold back on purchasing houses to get better position in the next round, but it is still a great mechanism to make sure that inferior players have limited ability to affect the game in a negative way.
Other games that solve this problem are Caylus, Agricola, Citadels, and pretty much any other game where turn order can be bid for, and is not set in stone. Also, many game sthat have limited player interactivity, such as pure racing games, do not suffer because turns are effectively, if not actually, simultaneous. Also, this problem obviously does not occur in two-player games or co-op games.
I generally highly discourage any modification to games. Players are not game designers, and without incredibly thorough play-testing by professionals, any so-called house rule you come up with will probably just ruin the game, even if you don't realize it.
If you absolutely feel compelled to modify a game, here is a general method to follow. First, determine if it is better to go first or last in any given round. For the sake of example, let us say it is advantageous to go first. In the first round of the game proceed as normal. Then using some quantifiable measure, rank the players as to who is in the lead. Since going first is advantageous, have the person in last place go first, second to last place go second, and so on. Redo the turn order at the beginning of every round by this same measure.
This modification will in all likelihood ruin your game, as skilled players will take advantage of the system to go first/last when they need to. It also allows for increased chance of error, when someone no doubt accidentally takes their turn out of order. Yet, it will fix the problem of sitting to the left of the weakest player under most circumstances.
Comment: If you don't realize it, was the game really ruined? And how are you supposed to TRULY understand a game if you've never modified it? I personally modify my games all the time, and I see no reason to discourage people from doing so if it makes the game more fun for them. :D
Comment: This is a great answer.  I don't feel the last 2 paragraphs are needed though.
Answer: We long-ago made a set of 'random position' counters for games where player order matters; one with the name of each player in our group.  Then we deal out the seating for the game at random.  This doesn't solve the problem in any individual game, but on average everyone comes out even.  Getting the worst player as in a good place for your or the best as your most-likely attacker becomes just another random factor of the game - in the long run, luck evens out.
I don't know any games offhand that are absolutely ruined by this kind of position difference, unless the gap in skills is so great as to be a problem no matter what - in which case you might as well admit that and make it a relaxed teaching game.
Comment: "I don't know any games offhand that are absolutely ruined by this kind of position difference..."

FWIW: 7 Wonders would be such a game.  If there's one player who is slightly worse at drafting games than the rest of the players, the player to their left has a notable advantage.
Comment: @invisiblejon: Thanks for that; I haven't played 7 Wonders, and it's interesting to know that there's a case where it *really* matters.
Comment: Glory To Rome is another such game.  In my gaming group, Craftsmen are so highly valued as patrons that we (almost) always use Jacks to lead/follow as Craftsmen.  When the new player is using his actual Craftsmen to lead/follow the Craftsman role, this gives the next player an easy way to pick up a Craftsman as a client, which makes all of their future Craftsman actions much more powerful.  I used to be this weak player that handed out Craftsmen to the veterans, until I learned better.
Answer: When it's clear that one player has an advantage over all the others, my group often has fun by conspiring against that player, and if people are playing the game for enjoyment it can end up being pretty fun. Once my family noticed that I tended to win more than any of them at Settlers of Catan, they started to be very careful about what trades the offered me and, if I was winning, they'd all combine forces to make sure that robber was on me at all times. The same thing happens in Puerto Rico.
Experienced player to new player before me:

"No don't pick craftsman! That means he'll get to ship his goods first and get more victory points than us! Pick Builder so he doesn't get that stack of $$$!"

New player thinks about this fact and reconsiders. Picks the Builder, thwarting my plan. The other players had fun conspiring against me, I had fun being conspired against, and the unfair advantage I would've had was gone. What's not to like?
Now I don't win as much any more, and when I do it's far more of a treat. My opponents have fun trying to thwart my plans and I have fun scheming to win and laughing when I don't. If you have a new player at the table you probably won't have the super-cutthroat experience you might have if all the players were of equal skill level, but that doesn't mean you can't have fun. :D
Answer: I think it really depends on the game and the situation.
If I am new to a game, it doesn't really matter where I sit, until I become experienced enough to understand the positives and negatives of a seat position.
If I'm just a bad player, well, then I am not in any better position no matter where I am.
This being said, we try to shuffle seating regularly when playing several rounds of a single game.  Depending on the game, we will also sit according to final score/placement, winner getting the first seat, then on down to the left.  This helps with games like Puerto Rico and some other games that tend be a bit harder for those going first.
Comment: Winner first then down to the left means the best player has the worst player to their right, which is a huge advantage. Why not loser first then up to the left, so that each player except the worst has a slightly worse player to the right?
Comment: @Sparr - Again, it depends on the game.  For example, When playing Puerto Rico, the 3 & 4th place players have a distinct starting advantage over the first (and second).  I can see where having the least experienced on your right would be helpful also.
My suggestion would be to roll dice for seating position, or have opposite players move 1 space right, just mix it up.
Answer: Given honest players, some of whom have a grasp of the game at hand and this problem, I have often found that simply seating players in order of skill/experience mitigates this problem somewhat.
Comment: If you seat them worst to best (in order of play), then the best player goes after the second-best player, and the person to benefit from the worst player's play is the second-worst player.
Comment: The problem with that is that the worst player sits next to the best player.
Answer: If there is too much of a difference between players such that winning is not an option for the "lesser" players, try to focus on having fun. The players won't return if they always lose.
Another option is to team up. Make a team with a couple of an experienced players and a new player, so the new player can learn from the pro without the need to be beaten.
Answer: My recommendation would be to switch the seating every few turns/times around the table.  Not so often that it slows down the game, but just enough that nobody sits next to the less experienced player for a time that would give them a major advantage.  Just my opinion on the topic.
Answer: This question makes me wonder:
How many games where turn order is the same from round to round would be "ruined" if you selected turn order randomly every round, with the caveat that no player could go twice in a row?
In other words, what if you re-organized turn order at the end of every round?
Note that I don't think this is a very practical solution, since the act of re-ordering turns at the end of each round would add at least another two minutes per round, but it's conceptually interesting.
Comment: That's not an answer, but a comment. An interesting comment, at that.


Ubuntu 12.04 Bootloader failed to install

Question: Sorry about the excessively long question, but I figured giving more information would be better.
I recently bought a new desktop for myself, running Windows 7. It has two hard drives, and I wanted to install Ubuntu on a small partition on the second hard drive. I created 25GB "free space" in Windows and ran a LiveCD install. I wanted to select the install options myself but accidentally selected "Install alongside Windows 7," but it seemed to pick up the free space and installed itself there as I wanted it to. However, I was told that the bootloader installation had failed. I chose to "Cancel installation," leaving my computer unable to boot. I wiped my computer and reinstalled Windows.
After that, I tried installing Ubuntu through Windows using WUBI, once using files from my LiveCD and once downloading everything again. Both times the install succeeded, but both times when I restarted and tried to load Ubuntu, it gave me an error - wubildr.mbr was corrupt or missing. I checked in Windows - it was indeed present on the C:\ drive.
I went back to the LiveCD installation, this time going the custom options route. I assigned 16GB to an Ext4 journaling file system and 10GB to a swap file. I got the same bootloader error as before. Being prompted to select a different partition to install the bootloader to, I first tried the partition Ubuntu was installed on. A window came up saying that the install had succeeded, but a second window gave me the same error and choices as before. I went through every single option it gave me, including the Windows partition and the hard drives themselves (dev/sda, dev/sdb). Same result. I then chose to not install a bootloader. Windows still works fine, and I assume Ubuntu has installed but is unbootable.
Knowing that my computer could potentially brick itself again - and, this time around, with a lot of data to lose and hassle to go through if I mess it up - I really don't want to do anything without some advice. So I'll ask this:

Why did the bootloader fail to install? Can I fix the error and install Ubuntu fresh?
Is there any way to get around the error, install the bootloader, and point it towards an existing installation of Ubuntu?
Is there a quicker and easier solution I might have missed?

EDIT: Thanks for the tip, AthloX. After testing the liveCD in Virtualbox with no installation problems, I looked around for some alternate bootloaders but had no success.
I attempted another install, which installed the bootloader and Ubuntu just fine but bricked Windows 7. I wiped both hard disks clean, including some "System Reserved" partitions I hadn't noticed before, before re-installing Windows 7 on one hard drive and immediately afterwards installing Ubuntu on the other.
Now the computer boots into Windows, but I can pop into the BIOS at startup to boot into Ubuntu via it's bootloader, and I'm guessing it'll only take a bit of poking at the BIOS to swap the load order.
Answer: I think its a problem with your Ubuntu Live CD. Try to download a new copy from here. Ubuntu also needs a swap area allocated not just free memory space. This document says why you need it.Swap.
Answer: Check out if your ubuntu install cd is not corrupt. Possibilities of corrupt cd try it in virtualbox in win7 before going physical. If its working fine, then select the appropriate hard disk as you have two; to install the bootloader to their MBR sector, check the same hard disk is first booting in BIOS setting.


My first bitcoin transaction with core and coldcard

Question: I use coldcard and bitcoin core 0.20.1. I have checked how to do it with HWI at https://github.com/bitcoin-core/HWI/blob/master/docs/bitcoin-core-usage.md.
It appears more complex than needed.
With the core's GUI, I can create a PSBT, save it, and then sign it with an SD card and coldcard. The latter will create a TXN file with the finalized transaction, that I can just broadcast with core.
No need for HWI and only 1 console command (sendrawtransaction) needed.
I am afraid: am I missing something?
Thank you for any suggestion.
Answer: That is a viable method for using a Coldcard with Bitcoin Core. HWI is intended for the case where the hardware wallet is plugged into the machine running your wallet software. For the Coldcard, it is just an alternate way to use it. However for other hardware wallets, the MicroSD card method is not available so HWI provides a way to use them with Core.
Comment: Thank you Andrew, that make sense and I better understand now the context of HWI. I did it the easy way and it worked for me. I will document below my experience.
Answer: From the coldcard site there is a link (above) for using coldcard with bitcoin Core. The first sentence is the following: "As of Bitcoin Core v0.19.0+ the setup can be done fully airgapped, but spending needs a USB connection and additional software such as HWI."
In the sense of Andrew's reply this make sense, however it is also possible to spend airgapped funds without an USB connection and without HWI. I will record my experience, I hope it helps those with my configuration (Core 20.1, Coldcard Firmware 3.1.9).

Create a watch only walled in Core as in the link above
Press "Send" in the Core toolbar
Enter your transaction in the Core GUI
Press the "Create Unsigned" button
Paste the PSBT in your favorite text editor and save it on a MicroSD card as a file with a PSBT extension
Insert the MicroSD in your Coldcard and hit "Ready To Sign". The Coldcard will sign the PSBT and create 2 files on the MicroSD card, a PSBT and a TXN file.
Open the TXN, copy the content in the clipboard
In the Core console hit "sendrawtransaction" and paste the copied TXN
Hit enter, and your transaction will be broadcasted.


How do you choose which acoustic piano to buy?

Question: Which things should one keep in mind when thinking about buying an acoustic piano?
Age, wood, brand? What things are high quality or bad quality? What to watch out for?
Answer: The most important aspect of buying a piano is to get one that you enjoy playing and that has a sound you find pleasurable. There is no correct answer here and really boils down to personal preference with regard to tone and action. Do you prefer a bright, sharp high end, or a deeply resonant bass? Do you prefer a heavy action that requires great muscle power to play loudly or a lighter action?
Another thing to keep in mind is that the tone of new pianos changes with use and becomes a bit more mellow over time. That said, unless you're planning to buy an extremely high-end instrument, a new piano is likely to be preferable to an old piano (that has been sitting neglected in someone's living room for decades, for example)--recent advances in piano manufacturing technology have made pianos better than ever.
Third thing is that the better the brand, the more the piano retains its value as it ages. For this reason and because presumably you'll become a better pianist as a result of owning an instrument, I would suggest buying the best brand you can afford. Piano manufacturing is incredibly competitive and brands take great pride in the consistency and quality of their offerings--that said, a new Steinway is always going to be more fun to play than a new Boston, which will be more fun to play than a new Baldwin, which (usually) will be more fun to play than a new Yamaha or Kawai. Avoid no-name or lesser known brands if possible as instruments by these manufacturers these tend to have a poor tone and go out of tune quickly.
Comment: What makes a Steinway more fun to play than a Yamaha? (I'm not criticizing, just curious; I don't know much about acoustic pianos.)
Comment: Again, everything is subjective, but the main reason professional pianists overwhelmingly prefer Steinways is because first: they have nearly infinite sensitivity to user input in terms of dynamic range (easier to make your softs softer, your louds louder) and second: tone control in general. In terms of control, action, tone, and feel, the experience of playing a Steinway or a Bosendorfer compared to playing a no-name brand is roughly like driving a BMW M3 vs. driving an broken-down 18-wheeler.
Answer: If you have to buy a piano and you cannot judge the quality of the piano by yourself, you should go with somebody who knows better to try it. This somebody could be a good piano technician or a professional pianist.
Other than that, don't trust cheap brands. They use cheap materials and careless manufacturing which, in the best of cases, will translate in manteinance problems. Pianos are complex, fine machinery that need to be very well made.


Whiskey - Irish vs. Scottish

Question: I know that, in general, Scottish whiskey is peaty because of the way they dry the malt with peat smoke while Irish whisky is not because they use unpeated malt.  Is the difference legally established in these two countries or is it convention?  Can an Irish distillery make Scottish whiskey and vice versa?
Comment: BlackSquare - most Scottish whiskies are not peaty. However all Scotch Whisky is spelt whisky, not whiskey.
Comment: If the nation has an 'e' in it's name, it has an 'e' in whiskey. Like, Ireland and America. Otherwise it goes without, like Scotland, Japan, and Canada.
Answer: Legally, a Scotch Whisky is a distilled spirit made in Scotland from cereals, water and yeast and has been matured for a period of not less than three years (The Scotch Whisky Regulations 2009).
An Irish Whiskey is distilled in Ireland and aged for a minimum of three years in oak barrels.
Thus an Irish distillery can not produce a Scottish whisky!
However our question does not end here because the Scotch Whisky Regulations 2009 define five categories of Scotch Whisky:

•Single Malt Scotch Whisky: A Scotch Whisky distilled at a single distillery using only malted barley.
•Single Grain Scotch Whisky: A Scotch Whisky distilled at a single distillery.
•Blended Scotch Whisky: A blend of one or more Single Malt Scotch Whiskies with one or more Single Grain Scotch Whiskies.
•Blended Malt Scotch Whisky: A blend of Single Malt Scotch Whiskies which have been distilled at more than one distillery.
•Blended Grain Scotch Whisky: A blend of Single Grain Scotch Whiskies which have been distilled at more than one distillery.

But some Scotch Whiskies have a smoky flavor which originates from the peat fire over which the green malt is dried, prior to grinding and mashing.
Hold on for one moment, "in Ireland, whiskeys distilled at Cooley are only distilled twice, and they make smoky whiskeys there too (Connemara)."
Thus the question as what the differences are between an Irish Whiskey and a Scotch whisky, other than how one spells whiskey remains a question of geography!
Comment: To add to your post, the 'smoky' flavour isn't a characteristic of every or even most Scotch whiskies either. If you do a quick search on Google you can find flavour charts where Scotches exist on a continuum between smoky and floral, and in the other direction light vs rich bodied.
Answer: The answer is partially historical. In the 1900's Ireland's distillery market was hit hard. Starting with the Irish War of Independence from 1919 to 1921, prohibition in the United States between 1919 and 1933, then a trade war between Ireland and Britain from 1932 to 1938, and finally WW2 starting in 1939. By the 1970's Ireland only had two distilleries, Midleton which made Jameson among other things, and Bushmills. So what we think of Irish whiskey is based largely on what two distilleries were making and what they could sell. Ireland's spirits economy has finally started to recover with the number of licensed distilleries doubling between 2014 and 2016, from 9 to 18. Today there are over 30, and eventually the limited perception of Irish whiskey will change as more small distilleries do new and exciting things.

Whiskey - Irish vs. Scottish


My grandson wants a LEGO motor. What should I get?

Question: My grandson wants a LEGO Power Motor to use with his gigantic box of Lego pieces.  He is 11 years old and seems to know his way around the world of LEGO bricks.  I, though, haven't a clue what he is asking for. I see things such as "EV3, NXT, RCX, and NXT-G and I'm confused. Can anyone help me?  What is it I'm looking for?
Comment: See Alex' answer, with the following note: There is a combo box that sells a battery box (the AA type) and an M-Motor, plus LED lights, a couple of gears and a polarity switch for (US) $30. It's not typically available in normal stores, but online at shop.lego.com as well as in LEGO brand stores. That's your best deal.
Answer: You say he is looking for a "Power Motor", which sounds like he is referring to the LEGO Power Functions line. The bare minimum you need to get a spinning motor would be one of the battery boxes and one of the motors.
Battery Boxes:

AA Battery Box
AAA Battery Box
Rechargeable Battery Box (requires Transformer 10V DC)

Motors:

M-Motor
L-Motor
XL-Motor

(They also make a servo-motor and a train motor, but these are made for special purposes.)

The terms you listed however refer to the different generation of Mindstorms robotics.

EV3: Current generation
NXT: Previous generation
RCX: First generation (rather old and difficult to use with modern computers)
NXT-G: The GUI used to program the NXT robots.

Mindstorms do include motors, among other things, but are mainly geared towards use with robotics.
Comment: Alexander you have been very helpful.  I assume that the upper half of your reply is what I'm looking for and we won't worry about the lower half since you lost me there!  This is a great web page for Grandparents.
Comment: Note that there is a combo box that sells a battery box (the AA type) and an M-Motor, plus LED lights, a couple of gears and a polarity switch for (US) $30. It's not typically available in normal stores, but online at shop.lego.com as well as in LEGO brand stores. That's your best deal.
Comment: @Phil, the set you are referring to is 8293. If the grandson already has a lot of Technic then this is a good way to motorise it https://shop.lego.com/en-NZ/LEGO-Power-Functions-Motor-Set-8293
Answer: While Alexander's answer is completely correct, I wanted to provide an alternative that may work a little better while being a bit more expensive. Buying a motor and battery box is certainly the cheapest way to get a spinning motor, but depending on your grandson's collection, this might not provide the best experience.
In order to build creations that operate using motors, it is helpful to have the following in addition to a battery box and motor:

Gears
Axles
Wheels that fit axles (the majority of wheels in the LEGO system are not designed to be driven by a motor)

These pieces form what is commonly branded "Technic", though they are found in non-Technic sets which sometimes feature moving parts.
It can also be helpful to see how motors are used within the larger LEGO system. The best way to get all the needed components and see them in action is to buy a complete set that is motorized. For example:

This set contains loads of axles, wheels, and gears, which together provide a great base for mechanical building. Sets like this are typically expensive ($150+), but could be worth it to you depending on your means.
Here's a list of currently available Technic sets that include electric motors.
Also, to directly respond to your confusion over the many acronyms, the current manually controlled motor system is called Control+ (the previous, and now incompatible, system was called Power Functions). Everything else (EV3, NXT, RCX, etc) is related to robotic and computer controlled motors.
Comment: I second this. Getting a motor by itself probably isn't enough. You need a decent collection of gears and technic bricks/beams to make even a simple machine.It also helps to get some of the gear boxes or other specialized parts. Buying any of the motorized Technic sets is a good way to start.
Answer: If your grandson has lots of Technic pieces, such as gear wheels, axles, beams with holes etc (if he knows his way around Lego he should be able to confirm that pretty easily), the Lego have a good starter set which contains a motor, battery box and a few other pieces. It's how I started updating my old LEGO Technic sets from the early 90s to be motorised and eventually radio controlled.
https://shop.lego.com/en-NZ/LEGO-Power-Functions-Motor-Set-8293


The 8086 has AAM (ASCII Adjust after Multiply), why not the same for packed BCD?

Question: I'm just curious why the 8086 seems to be lacking in an adjust opcode for fixing up packed BCD multiplication. It seems like it would be a useful thing, and packed BCD seems to be more common to begin with.
Answer: To adjust a value, one needs to know how many carries there were out of each decimal digit.  When adding two 8-bit numbers, there can be at most one carry out of each 4-bit chunk, which will fit in two flags which are devoted to that purpose.  Multiplication of two decimal digits, however, may yield up to eight carries--far too many to fit into two one-bit flags.
Consider, for example, the multiplication of 0x12 by 0x04, 0x18 by 0x03, or 0x09 by 0x08.  All three will yield 0x48 prior to adjustment, but they have different numbers of carries out of the bottom digit, and should thus yield different values after adjustment.  The first has no carry out of the bottom digit and should stay 0x48.  The second has two carries out of the bottom digit and should have 12 (6 per carry) added to yield 0x54.  The third has seven carries out of the bottom digit and should have 42 added to yield 0x72.
There are ways of designing circuitry to multiply packed BCD reasonably efficiently, but doing so would require continuously updating the result for BCD during the multiplication process, rather than at the end.
Answer: AAM is needed because the result of multiplying two unpacked BCD is a 'strange' value that needs to be 'normalized' again.
The whole mechanic of using the binary multiply with BCD only woks with 'unpacked' values. Using two packed BCD values will return a result that can't be decoded as easy.
To allow multiplication with packed BCD would have required the addition of decimal multiplication functions as separate operation, a quite complex one, as the 8086 does not contain any decimal units, but repurposes the binary ALU - much like the 8080 did. And that's why it needs the 'correcting' instructions.
If one needs high performance BCD, the usage of a 8087 would be recommended
Comment: Is "decoding" a MUL performed on two packed BCD values actually even possible?
Comment: @8086fan I'd say no, but  i wouldn't wonder i there is some obscure way. So better be careful :)
Answer: It does not have an opcode to perform packed BCD multiplication, so there is no point having an adjust opcode for that either.
Comment: The whole point of such opcodes is to reuse normal binary arithmetic ops. The 8086 doesn't have an explicit packed BCD add or subtract op either.
Comment: No, they are not separate, but they have built-in support for packed BCD, using the Auxiliary Flag as the half-carry for the least significant digit, and Carry Flag for the most significant digit. The MUL does not have built-in support, or flags dedicated to it, to multiply two packed BCD digits together, and to be able to adjust the result after it (if it is even possible, as mentioned by Raffzahn).


HTTPS, HTTP Headers, Privacy and Tor

Question: I have several doubts regarding the HTTPS protocol:
- First: Are the HTTPS headers encrypted? I mean, HTTPS encrypts the content, but does it also encrypt the headers?
-Second: Navigating with, for example, Chrome, through the HTTPS protocol, is it safe for privacy? I mean, imagine that the police are analyzing my network traffic through a sniffer. I am browsing with a normal browser but through an HTTPS page, can the police track me? And Can the police know the server to which I am sending data?
Third: The main purpose of Tor is to hide the user through the three nodes. But my question is: If using HTTPS only the connection is encrypted, and the HTTP headers are encrypted, how can the user be tracked if everything is encrypted?
Four: Does using HTTPS also encrypt IP?
Thank you.
Forget my English, English is not my mother tongue.

I add more doubts...:
I have just opened this thread as a result of this animation (https://www.eff.org/pages/tor-and-https). That animation is very explanatory, but it also gives me doubts.
First: According to that image, if I only surf with HTTPS, people (Police, NSA ...) can track me. At first, I thought that maybe they could track me because of HTTP headers. But now I know that HTTP headers are encrypted in HTTPS. So I guess they can track me, for example, thanks to the IP, which is not encrypted (among other elements, like cookies or fingerprinting). Right?
Second: According to that image, when I navigate through HTTPS, the Police or the NSA can know to which web page I am connecting. Our fellow canonizing ironize has said that "they know who you are and what site you are using (because) the site you are connecting to is not encrypted. The resource you're fetching from the site is". I do not quite understand this. I mean, if the HTTP headers are encrypted, the "Host" request header is also encrypted. So how do they know the site I'm connecting to?
Third: Look at the animation (https://www.eff.org/pages/tor-and-https), please. These next questions are very important.
A) If I am using Tor and HTTPS simultaneously, according to the image, if there is a hacker monitoring my router he only receives one information: "Location Tor". What does this mean? He can not see my information (is encrypted because of HTTPS), but does he know my identity? (Imagine that the hacker is monitoring a router in a huge building with many routers. The hacker does not know exactly which router he is monitoring, he only knows that it is in that building. If I use Tor and HTTPS, the hacker can see my real public IP? I say it because the information has not gone through the three nodes  yet...).
B) According to the image, if I use Tor and HTTPS simultaneously, my ISP and a possible NSA agent that monitors the Network BEFORE the first Tor node, can see the same thing as before: "Location Tor ". Can anyone explain this to me? What does it mean? I think it means that he can know WHO the information comes from, but not WHERE TO GO. But this means that Tor is vulnerable ... In the same way, the first Tor node can see "Location Tor" ... What does this mean?
C) According to the image, if I use Tor and HTTPS simultaneously, the third Tor node, as well as a possible NSA agent located AFTER the three nodes; the ISP of the site that I connect to and the website can see the site to which a Tor user connects ("Site.com") and nothing else, right? That is, they can see the site to which a connection is connecting, but they can not know where the connection is coming from, right?
D) Imagine this situation ... I am using Tor. The NSA is monitoring ALL submarine cables, as Snowden suggested ... Okay. Then, there is an NSA agent monitoring the Network BEFORE the first Tor node and another monitoring the Network AFTER the third node. They detect all my traffic. According to the image, the first agent receives "Location Tor", and the second agent receives "Site.com" (the website to which I connect). If they share the information, can they know my identity?
I know there are a lot of questions ... I'm sorry, but I think they're interesting. Thank you.
(Forget my English please; English is not my mother tongue).
Comment: You might find this animation informative. Javascript required: https://www.eff.org/pages/tor-and-https
Answer:
Are the HTTPS headers encrypted?

Yes, in HTTPS the headers and the requested resource are part of the "content" that is encrypted.

I am browsing with a normal browser but through an HTTPS page, can the police track me? And Can the police know the server to which I am sending data?

Yes, they know who you are and what site you are using, the site you are connecting to is not encrypted. The resource you're fetching from the site is.

how can the user be tracked if everything is encrypted?

Covert and overt tracking mechanisms, e.g. cookies and cache. See this document for some examples.

Does using HTTPS also encrypt IP?

No, HTTPS traffic is sent over IP, it cannot encrypt the layers below it.

if the HTTP headers are encrypted, the "Host" request header is also encrypted. So how do they know the site I'm connecting to?

A feature of TLS called "Server Name Indication" or SNI. Also in TLS1.2 or less the certificate is sent in plaintext (not so for TLS1.3).

If I use Tor and HTTPS, the hacker can see my real public IP?

A local observer sees you are using Tor and where you are located (since they're local), the see nothing of what you're using Tor for.

the third Tor node...can see the site to which a Tor user connects

Yes, they see the data that you sent into the Tor network, which is HTTPS traffic.

If they share the information, can they know my identity?

Yes, this is a fundamental limitation of low latency anonymity networks.
Comment: canonizing ironize Thank you very much! I have put more doubts above, related to this animation: https://www.eff.org/pages/tor-and-https If you could help me with this doubts, please... Thank You Very Much!
Comment: Updated, most of these questions are covered in one form or another as separate questions on here, though.

HTTPS, HTTP Headers, Privacy and Tor


ArchLinux in VirtualBox crashes (host Ubuntu)

Question: I'm trying to run ArchLinux in a VirtualBox VM but each time I start the VM it seems to crash. I see Arch booting up to this line:
<code>::Loading udev...
</code>
It pauses there for say 30 seconds, then I briefly see next line but before I can read what is says the VM crashes. I've tried different settings in VirtualBox like enabling the PAE/NX which e.g. is necessary to run Ubuntu server, but nothing seems to work so far.
These are the specs:

Ubuntu 9.04 Desktop (host)
VirtualBox 2.2.4 r47978
ArchLinux 2009.08-core

Crash log:
<code>Log created: 2009-08-29T22:28:11.322825000Z
Executable: /usr/lib/virtualbox/VirtualBox
Arg[0]: /usr/lib/virtualbox/VirtualBox
Arg[1]: --comment
Arg[2]: Arch
Arg[3]: --startvm
Arg[4]: a8efa91d-d8f5-4eb1-9996-dc023004e0ce
Crash in patch code ff1954cc (c0305dc8) esp=de281d0c
Patch state=4 flags=10c0081 fDirty=4
<NULL>
</code>
Answer: This topic might be relevant


Should English/English-style beers be served warmer, since that is how the taste was developed?

Question: Given that the British tend to drink their beer at a higher temperature than those of us in the US, should beer brewed in an English style be consumed that way? The justification I can think of is: the people developing the taste of the beer probably consumed it at a certain temperature, which might have not been the ice-cold levels that predominate in the Colonies.
Comment: warm light beer in summer outside is a UK cultural wonder
Comment: I'd like to know how Guinness, in particular, should factor into this equation... It's Irish, I know. But, as far as concept - there are fascinatingly intricate serving rules associated with both the pour and temperature. I like it warm and cold..
Answer: Serving temperature is, of course, a preference.  Serve it frozen or boiling if you want.  However, a few opinions are:

CAMRA says that Real Ale (aka cask ale, usually english-style) should be served at 12-14 °C (54-57 °F), which is colder than room temperature, but warmer than your usually keg beer.
Ratebeer says the same thing regardless of whether it's cask or not.
BeerAdvocate says 7-10 °C (45-50 °F) for an english bitter.

So, if you're looking for a rule of thumb: "cool but not super-cold" or "cellar temp" will probably get you close enough.
Answer: There may be a general consensus for the "proper" serving temperature, which could involve questions like "what do most people seem to like?", and "what temperature does the brewer feel best accentuates the parts of the beer they want to highlight?".  So there are good reasons for beer to be served at particular temperatures.  In the case of your British bitters, age-old recipes were probably designed to allow the beer to taste its best at room temperature.  As for a modern British beer, I suppose that would depend on what the brewer had in mind.
That said, my general thought is that you should drink a beer at the temperature you most like it, so the should part of your question is self-determined, and don't let anyone tell you that your taste buds are wrong.
Myself, I tend to like my American IPAs cooler than the typical recommended serving temperature.  And before I visited the UK, I couldn't stand a room temperature beer.  Then, after a week in Tunbridge Wells, I picked up a large appreciation for hand-pumped UK beer, served at room temp.  So you should open yourself to trying new things as well.
Answer: Just like everyone else said, it's a preference. I alway say that the darker the beer, the warmer it has to be, so here are my rules:
- Light beer/White beer/Kriek: In the fridge and goes in the freezer for a couple of minutes before serving
- Golden beer: In the fridge
- Amber beer: In the fridge and stay at room temperature for a couple of minutes before serving
- Dark beer: At room temperature and goes in the fridge before serving
- Stout: At room temperature at all time.
Answer: The basic rule is that beers should be served at the temp they were fermented. Lagers should be served at about 40°F and ales around 50°F - 55°F.  Having said this I usually like my beers a little colder on a warm summer day. Try this experiment:

chill your beer to 35°F - 40°F and pour about 2/3 of it into the proper glass for that beer.
Drink at least 4 or 5 sips, gulps, or however you typically consume it.
Then put what is left in the microwave for about 20 seconds (time will vary with the output of the microwave).  This will reduce the carbonation some so pour the other third right in the middle of the glass without tipping the glass to get some head, on the beer that is.

It makes a big difference on some beers. less on others. Also try different types of glasses and see what you like. Remember, everybody's palates are different and yours will vary depending on several factors such as, what you've been eating or drinking, how much beer you've already consumed, and how tired you are. It's a good idea to eat a bite or two of good bread like a baguette to cleanse your palate between samples. The above does not apply to mass produced lagers.
Answer: It's always going to be a matter of preference. I prefer most beers around 55-60 but do not hesitate to drink beer at room temperature. Some styles are more enjoyable approaching room temperature.
Historically, most beer was served at cellar temperature to room temperature, depending upon what was available. That isn't just an English tradition. Any beer can be consumed warm and drinking it ice cold as mass produced lagers are usually served tends to hide most of the flavor that you are paying for in a good beer. Give it a try and see what you like. Maybe you don't like your beer a little warmer. Enjoy what you like.
Answer: First, let's say there is what is considered "proper", and then there is personal-preference. To be a good Cicerone, know what is "proper" but also show tolerance for personal preference.
With that out the way, it's definitely considered the "proper" thing to do to serve English beers warmer than ice-cold. Many of the delicate malty flavours you get from English malt, the fruitiness from esters produced by the English yeast, plus grassy, herbal or floral tones from the hops are muted greatly when the beer is served too cold.
Some people say it's served at room room temperature. Modern room temperature of around 20°C/68°F is too warm. The ideal serving temperature is a cold cellar - typically around 12°C;55°F.


What is the most efficient way to test whether a set $X \subset \{0, 1\}^n$ and its complement $\{0, 1\}^n \setminus X$ are linearly separable?

Question: I am interested in algorithms that have optimal running time, and ideally which are also very easy to implement.  If you can also give some tips on how to implement the algorithm(s) you mention in the answer, that would be great.
Comment: https://math.stackexchange.com/questions/412057/characterisation-of-linearly-separable-points-of-a-hypercube
Answer: Actually, no algorithms, efficient enough for you to be interested in, are available. Your problem is exactly the membership problem for the class of linearly separable boolean functions (which are the indicator functions of your sets), and it is known to be co-NP-complete.


Are all vectors straight lines?

Question: Is there a math field that deals with quadratic, cubic etc. vectors? Or a non-linear equivalent of a vector? If so, why are they so much less common than linear vectors?
Comment: What do you consider a *linear vector*? For many mathematicians, vectors are just elements of vector spaces.
Comment: @rschwieb A vector that can be represented as a segment of a line.
Comment: So what is a *quadratic vector*? A curve bent like the graph of a quadratic equation is?
Comment: Maybe you could think of a parametrized curve as being a curved vector space?
Answer: Formally, a vector is an element of a vector space. Other than the usual Euclidean spaces, we have other vector spaces, such as the space of all continuous functions on the unit interval.
What you have learnt in school is probably this: visualise say $(1,2)$ as an arrow pointing from the point $(3,4)$ to the point $(4,6)$. Now instead of thinking about this $(1,2)$ as an arrow moving one unit right and two units up, we associate it with the point $(1,2)$ in a horizontal plane. Then the set of all these vectors is simply associated with the set of all points in the plane ($2$-dimensional Euclidean space).
Comment: Sorry we just started vectors and I have no idea what a vector space is. Could you please simplify your answer?
Answer: From your response to my comment in your OP, I'll talk about why vectors are always considered "rays" geometrically.
The most important interpretation of a vector is as a list of numbers (we'll say from $\Bbb R^n$.) The list of numbers determines a point in $\Bbb R^n$, and if you imagine connecting this to the origin with a straight line and adding an arrowhead at the end with the point, you have a "ray" representing the vector. Actually you can slide this ray (without changing the direction) all over space and still have the same vector. Strictly speaking it is not a segment because it has a fixed direction. If you put the arrowhead on the other end, it is a different vector.
Since the vector only carries the information about a single point, it would does not determine anything more complex than a line. In order to "curve" the vector, you'd need to say more about the path it follows on its way from start to finish.
Another reason is that the points lying on the line determined by a vector through the origin are a subspace of the big space. Subspaces "aren't curved" in some sense. This property causes $\alpha v,\beta v, (\alpha+\beta)v$ to all lie on the same straight line.
Multiplying a vector (ray) in a real vector space by $\lambda \in \Bbb R$ just stretches or contracts the vector. If the vector were curved somehow, then scaling it would change the curviture of the shape. It does not seem desirable that a geometric property such as curviture is ruined merely by scaling the vector, so it doesn't seem very likely to be useful.
Answer: What you are considering to be a vector can be abstracted as follows: Place the line segment so that its one end is on the origin and the other end is somewhere in the Cartesian plane. The coordinates of the other end can be identified with this straight line and so may be called a vector. So for example $(2,3)$ is a vector.
This can be generalized to $3$ dimensional space, and in fact to $n$-dimensional space with the notion of a straight line joining the origin to the point. (You can abstract it even further in the idea of an arbitrary vector space.)
Now your question, if I am understanding it correctly, is as to why we don't consider curves instead of straight lines to geometrically represent the vector. We could, but that would unnecessarily complicate things: The curve would have to be carefully chosen so that it is defining an invertible function on $\mathbb{R}$ with an appropriate parameter to ensure all points could be represented. Straight lines are pretty simple to handle and satisfy this criteria and hence are used.
Answer: Vectors in the plane or in space are not lines; they are straight-line motions. You can add two motions to get a third, or scale a motion to get a larger or smaller motion in the same direction.  But they do not have a start or an end point the way a line segment does.
In more advanced mathematics, we consider more abstract vectors.  The fundamental abstract property of vectors  is that they can be added together, and they can be scaled, and that vector properties are suitably preserved  by these "linear" operations of addition and scalar multiplication: If $u$ and $v$ are vectors, so is $u+v$, and so is $cv$ for any scalar $c$.
So we generalize the idea of a vector from the idea of linear motions in space to the idea of any collection of objects with a notion of sum and scalar multiplication.  Looked at this way, all sorts of things can be treated as vectors, even things that have nothing to do with motions or straight lines. The benefit of doing this is that our understanding of vectors can be transported to these other domains to give insight about the other sorts of objects.
One supremely important example of such a domain is that we can treat functions of various sorts as vectors.  A function like $f(x)$ can be added to another function to give a third, and can be multiplied by a scalar.  There is a zero function, just as there is a zero vector; it is the function whose value is 0 everywhere.  Even the concept of vector dot product can be transferred appropriately to function spaces.  One can find an analogue of a basis for such a vector space, and show that every function can be represented as a sum of the basis functions.  This is the fundamental idea of the branch of mathematics called Fourier analysis, which is one of the most fruitful in mathematics, essential for understanding communications and signal transmission, digitization of music, and all sorts of other things.
For a less awesome but very typical example, see this answer where I showed how to find a polynomial $p$ satisfying $p\left(\sqrt2+\sqrt3\right) = 0$ by considering a certain vector space generated by the "vectors" $\left(\sqrt2+\sqrt3\right)^i$.   Once I had cast the problem in this light, I was able to conclude immediately that $\left(\sqrt2+\sqrt3\right)^4$ would be expressible in terms of $\left(\sqrt2+\sqrt3\right)^i$ for $0\le i\le 3$ because the vector space was only 4-dimensional and so no set of 5 vectors could be independent.

Are all vectors straight lines?


Testing cloud based applications

Question: Is there any fundamental difference in the way applications/services hosted in the cloud are to be tested versus a traditional web based application? It looks essentially the same to me except the way these applications manage large loads (elastic clouds) and high availability.
Answer: I think that Larry Elison summed it up nicely when he stated that Cloud computing is just, servers and the internet. Video is here -> http://www.youtube.com/watch?v=UOEFXaWHppE
Testing "Cloud" applications should be tested as though you would test any existing web application with a few added test cases to test the additional "Cloud" features, if you application has them:
Dynamic scaling You would want to test that the application can dynamically scale up and down, with no loss of data and end user connectivity.
Automated provisioning For apps that provision new services automatically when a new user signs up, you would want to test this process, as well as the reverse when a user leaves the service.
Device Synchronisation If the service is like Dropbox, or iCloud, then there may be device to device synchronisation issues that need to be tested, particularly recovery situations when a sync is disrupted and incomplete and needs to be restarted.
Answer: This really depends.
No if you have created virtual machines on the cloud and have moved your application onto those virtual machines and placed these behind the a load balancer. You might choose to check that the load balancer functions as expected, and the performance when you place you application under load to ensure you have the correct setting in place on the load balancer.
Yes if you have embraced the cloud technologies and built your application to deliver high availability and scalability. Your application components will be distributed across machines and you will find that testing a distributed system is best done by testing each of the components first in isolation through unit tests and then a smaller set of integrated tests to prove that the deployed application works as intended.
Answer: I found this nice article by Matt Heusser which nicely sums up software testing in the cloud.
Providing the link here to share with all those who are looking for some advice.
In other words (a short summary):
Cloud computing has made available two very useful technologies to the masses

Distributed computing
Virtualization

This creates new opportunities for testers to test quickly and efficiently. The challenges would be test around the edges of these services. Some of things to look are

Elastic clouds (automatic provisioning of computing power and memory)
Disaster recovery
Reliability
Synchronization (across devices and services)
Security
Comment: Nice link @Rajneesh - but could you give a quick summary in your answer?
Answer: Please check

SoftTest Webinar: Testing a SaaS (Software as a Service) Platform in an Agile World
http://www.blog.sogeti.ie/2010/04/softtest-webinar-testing-saas-software.html
Important takeaway from the presentation - Application related security (SQL Injections, Cross Side Scripting), Infrastructure related (Disaster recovery mechanism, Latency (Network, Data Transfer, Load balancing, Remote Monitoring)). Related Read - http://highscalability.com/blog/2009/7/25/latency-is-everywhere-and-it-costs-you-sales-how-to-crush-it.html
SaaS Testing Overview - Foundation
http://www.slideshare.net/ramgarg/saa-s-testingoverviewppt-5072671
Please check CloudTest Lite - cloud based free tool for performance testing web apps (http://www.soasta.com/info-center/press-releases/cloudtest-lite-edition-announcement/)

Developing Test Expertise in cloud based apps is different from traditional test approach. Particularly, How much load cloud can scale up is the key.
Hope it Helps.
Comment: Great links, but do you have anything to share from your experience?
Comment: We are in the initial Stages, I would share my learnig's  after go-live
Answer: Assuming that a 'regular' web application is one that runs on bare metal or a virtualized infrastructure with tight SLAs (two nines and better) and doesn't requires scale or elasticity, then yes there is a big difference.
Cloud VMs have an MTBF measured in months, so all components that your application depends on, computes, networks, storage, are error prone. Testing a cloud application thus becomes the problem of testing if your application behaves properly when any of these components fails. For the application to intelligently respond to failures cross-cuts into its functionality so fundamentally, cloud applications need to be tested differently.
The second big difference injected by the highly unreliable components (but highly reliable infrastructure: please note that difference) is that there needs to be automation to deploy these components. That automation is integral to the functionality of the application and can exhibit very complex 'convergence' behavior. You suddenly need to test for idempotency of configuration processes, or forward progress on convergence. Those are attributes that small fixed asset applications never had to include in their operational QA.
So, yes, big difference in QA approach between cloud applications and non-cloud applications. And clouds can be private or public, it is the MTBF characteristics of the components, elasticity, and scale that make the difference. Scalability is different from scale, and scalability does introduce a new functionality requirement, but testing for it is very different if you have 50 servers or 5000 servers.

Testing cloud based applications


What constitutes relevant and marketable work experience?

Question: I want to build up my resume, being able to claim more marketable experience, but my current position at work does not afford me the opportunities to move in the direction that I'm interested in. While my own home time can be used to learn and broaden my knowledge of different subjects, what can I claim in terms of experience that would be respected in a job interview?  How does personal experience stand up against on the job experience in the IT industry?
Comment: The edits do appear to bring this back in line, so I reopened. Anyone who answered may want to review the post and adjust his/her answers.
Comment: After reading the 'help' section, an appropriate question would be about interviews which is what this all circulates around, the perception to someone doing the hiring of experience and where and how it was gained.
Answer: Often was constitutes relevant experience is that which others can also speak of: experience where you have a manager who can give a reference.  As much as possible, you want to get the experience from a job, because that is what other hiring managers consider relevant.
Experience outside of a job can be a bonus, and certainly will help.  But if it is only gained outside of a job, you are competing with people with job experience, who have experience that a hiring manager can relate to.
Therefore, as much as possible, look for opportunities within your company.  At the same time, look for jobs outside your company that look like they are relevant to what you want to do, and apply for them.  Best case is if one of them hire you.  Next best case is you still have a job and are getting more experience, even if it is not quite what you want.
Answer: You're not a "full time" programmer, and you want to be.  The answer is quite simple - GitHub.
You need to do the following things.

Upload your own code up there.  Doesn't matter if it's not brilliant.
Commit bug fixes to your own code.
Fork other people's code - submit patches to them.
Write documentation / submit issues / help out with other people's code.

What you're showing to a prospective recruiter is:

I know how to use Git!
I have proficiency in the following programming languages.
I can submit good bug reports.
Look how I have developed over the last X months.

Writing on a CV / Resume "I know Java" doesn't mean anything.  You need to demonstrate your skills - show, don't tell.
Comment: I am confused how this answers the question: "What constitutes relevant and marketable work experience?"


Can I use store-bought custard for Portuguese Tarts?

Question: I always make my own custard when I bake Portuguese Tarts but want to take a shortcut. Can I use store-bought custard to make Portuguese Tarts? What kind of custard do I need to buy? Should it be at room temperature before I bake?
Comment: Are you asking about something similar to this:  http://allrecipes.com/recipe/portuguese-custard-tarts---pasteis-de-nata/  If so, it appears to be a standard custard.  While you *could* use a custard mix or buy a custard, since this is the star of the pastry, the quality of your outcome might suffer.   Custard is fast and easy to make; if you want a short cut, I would buy puff pastry or pie dough for the shell.
Comment: @SAJ14SAJ: Thanks, yes, that's a similar recipe to the one I use. I was just wondering if the store bought thick custard would do the trick
Comment: Without knowing the ingredients and method used to make the custard, it's not possible to know how it will react to being reheated.
Comment: I don't think you could get quicker than this buying them pre-made! [Jamie Oliver Video](https://www.youtube.com/watch?v=GTbRxpXjhIk)
Answer: Short Answer: Probably, but it won't taste as good.
Longer Answer:
Given that most packaged custards (if you mean the powdered sort such as Bird's or Jello) do not contain eggs, you might find that the custard does not behave quite the same and certainly will not taste as rich.  They tend to use yellow food colouring to give the bright yellow colour that you would get from the egg yolks. It's a bit like asking if you can substitute Cool Whip for Whipped Cream.  Yes, but....
Comment: The best shortcut I can suggest without seriously impairing quality is to find a good Portugese bakery.  Using store-bought pastry will be just as disappointing as using store-bought custard if you're used to making them from scratch.
Answer: If by store bought custard you mean something like Bird's custard powder, then no you cannot. Though I don't believe there is a hard distinction between them, generally what the English consider custard is more of a cream. I make the distinction, again this maybe somewhat arbitrary, in that a custard is intended to be cooked and set, which is what you're going for with the Portuguese tarts. A cream, on the other hand, is constantly stirred while heating to prevent setting, such as creme anglaise (which is what Bird's and other custard powders are intended to mimic).
Answer: Looking at this I would suggest that as opposed to a 'custard' that what would work, and taste better would be a store bought creme patisserie
In the uk where I am I would suggest either waitrose or marks and Spencer's
If you live abroad and can't get this then several uk food exporters sell around the world, including this one
http://www.britishsupermarketworldwide.com/acatalog/Marks-Spencer-Creme-Patissiere-300g.html
(Other retailers also carry this)


How can I pedal in circles?

Question: I couple of years ago I switched from using a normal pedal to using a clipless pedal. It takes a little while to get used to. Now, to be able to use it optimally I need to learn how to pedal in circles instead of in squares, eg applying the same force during the whole rotation "orbit". What do I need to think of to be able to pedal properly?
Answer: A technique which may help you get a more efficient pedaling stroke is an exercise called isolated leg. With your bicycle on a trainer or on a slight uphill, unclip your left leg and pedal using only your right leg for 30-60 strokes. Then switch and do the same for your other leg. This exercise will give a very natural feel to how your legs should be rotating to achieve an efficient pedaling stroke.
Answer: I was told to imagine that you are trying to scrape some mud off your foot. As you pull down from about 1 O'Clock, just as you reach about 5 O'Clock, start to pull your foot back, pointing your toes towards the ground, like trying to scrape some mud off the front of your shoe.  I am not too sure where you should stop this pulling, but I would say it is about 8 O'Clock, since by that stage your other foot should be starting to put some pressure on the other crank.
Answer: Mountain Biking is the best thing. Was just reading a training article by Chris Carmicheal (trained Lance Armstrong) and in studies he did mountain bikers had the best natural spin. They figure it came from climbing on loose dirt while seated to make sure you had good traction.
Another good exercise is to pedal with one foot. I do this once a week at the end of a ride. Only for a block or two but it really emphasizes the lack of pedaling in a circle.
Comment: As custismchale says, you don't need a coach, just hills with loose dirt. And don't only sit, climbing steeper hills gives smoothness out of the saddle, as well as a keen awareness of weight distribution.
Comment: True it does assume some level of knowledge on how to pedal up a hill. So, find some loose dirt on a bit of an incline. Stay seated and in an easy gear climb the hill without the wheel slipping. As you get smoother find a steeper hill.
Comment: That assumes you also have a coach who knows what they are doing and what they are talking about.  Just going out and riding in dirt is not going to help the situation.  I have seen plenty of mtn bikers with poor pedaling techniques.  However, the last sentence is a good one.  +1 for the one leg pedaling.
Answer: I find that the best time to practice making good circular rotations is when I am completely out of gear (doing 20mph in the granny gear, for example).  I ride a single speed, so this is pretty easy for me.  Being out of gear allows me to feel how circular my movements really are.  If I'm not pulling back at the bottom of my stroke and then up the back side, I feel the bike lurching around under me.
This helped me, maybe it can help you as well.
Answer: I certainly am no expert but some things that helped me

a set of rollers (not a stand/trainer) but rollers can help smooth your motion
"thinking in circles" helps as well.  Visualize the foot/pedal motion
Comment: +1 for rollers - if you don't pedal in nice circles you surge forward and backward. Nothing like a couple of minutes of that to get you to pay attention to your form.
Answer: There are a couple tools (both quite expensive though) that can help. It all comes down to muscle memory though, the more you spin the better you get at it.
Computrainer has a spin scan to help identify flat or dead spots in your cadence.
Powercranks force you into leg isolation by disconnecting the cranks from each other.
Answer: If you are after smoothness, then pulling up may improve your game. The concept that you need to pull with the upward-bound leg/pedal  is a myth that has been perpetrated because it feels good! It may be worth doing, for that reason, alone. ;]
But experts have found that max power is generated when concentrating on the downward leg while completely unweighting the other until it returns to the top of the stroke.
In order to smooth out your stroke, and locate the issues you are dealing with, doing hill repeats alternating one leg or the other will def help you find the weak spots in each leg's pedal stroke.
Answer: I got this trick off the Internet about ten years ago. Can't remember where, I'm afraid, or I'd credit the source.
Imagine that your feet are really hands, and that you're not pedalling, but winding yourself along some kind of rack-and-pinion track. Picture it, feel it, and keep that motion in mind as you pedal.
Our hands are much better equipped for the right kind of push-pull motion than our feet, so thinking of winding with your hands primes your motor cortex to keep a consistent amount of force round the whole revolution.
Stay vigilant: if you notice yourself going back to piston-pedalling, just think of hands again, and you'll soon make it a habit.
Comment: I once read from Greg LeMond to pretend that you are scraping mud off of your shoes.

How can I pedal in circles?


Proof about universal covers

Question: I have some Algebraic Topology notes that prove the following Lemma:

If $X$ is simply connected and locally path connected, then every covering projection $p:Y \to X$ is trivial (i.e. the whole space $X$ is evenly covered by $p$).

I understand this, and I understand the proof (it constructs a homeomorphism $Y \cong X \times D$ where $D$ is a discrete space). The proof is followed by the comment: "It follows that if a locally path connected space has a simply connected covering space, then the latter is unique up to homeomorphism".
I don't understand why this is true. I can see it's true if we transpose "locally path connected" and "simply connected", since $X$ is lpc iff $Y$ is. Otherwise, I don't really have a clue.
I'd appreciate any enlightenment. Thanks!
Comment: The missing ingredient should be a result on lifting. Say that $p\colon Y\to X$ and $q\colon Z\to X$ are covering projections, with $Y$ and $Z$ simply connected. Since $Z$ is simply connected, $q$ should have a lifting $Z\to Y$, thus making $Z$ a covering space of $Y$. Now apply the lemma. (Commented rather than answering because this may not be the way your textbook argues, and it's been too long since I studied this subject.)
Answer: If $Y,Y'\to X$ are simply connected covering spaces, there is an $X$-morphism $f:Y\to Y'$ (Massey, page 156), which will automatically be a covering space (Massey, p.168).  It will be an isomorphism because of the Lemma.

Proof about universal covers


Can you use just egg yolks when recipe asks for eggs?

Question: Having just made a batch of meringues,I am now left with lots of egg yolks, can I use them in recipes that ask for "eggs" i.e cakes and tray bakes. Is the white of the egg needed in the baking process ?
Answer: It really does depend on the recipe. Egg yolks have some protein but a lot of fat which adds flavor and makes baked goods more tender and moist.  Whites are just protein which adds structure and has a drying effect.
If the particular recipe is depending on the eggs for the binding power of their protein you may not get enough by substituting just yolks. Remember that the volume of the yolks is less than whole eggs so you may see better success substituting two whole eggs with three yolks.
Some cakes will handle the reduced protein. White and yellow cakes will be ok. Pound cakes will also be fine and in fact some recipes call for only yolks. Expect your cake to be a little denser, softer, and tastier. Any kind of sponge or angel food cake won't work because they rely wholly on the protein from the whites.
Soft, rich breads will also benefit from the added fat. The breads will derive their structure from the gluten in their flour. Cinnamon rolls and rich doughnuts come to mind. A local doughnut shop is famous for the yellow color which comes from using fresh yolks.

Yolks can be used in many recipes that call for whole eggs. Look for recipes that will benefit from all the added fat. Anything custard-like, where the eggs are mixed with milk, will work very well- even better than with whole eggs in fact. Examples are custard, flan, puddings, french toast, etc. Given the season you might consider a custard-based ice cream.
Comment: being in NZ though Ice cream not the best idea at this time of year :)
Comment: cool thanks, thats has answered my question ,very useful and yummy photo !
Answer: I have just made coconut macaroons which needed 2 egg whites so I just decided to use the 2 egg yolks and 1 whole egg ....with a 4oz flour and 4oz margarine and 4oz sugar mix and they turned out a bit moister than what I would normally make...so the kids will have a lovely treat for tomorrow for tea...:-) the mix has made lovely cakes...:-)
Comment: Hi and welcome to the site. I'm not sure what you're exactly saying here. The recipe called for two egg whites, but you used instead 2 yolks and an egg? Or you added those to the two whites, so using in total three whole eggs?


Set Specific Podcasts to Show as TV Shows in iTunes, using AppleScript

Question: I'm using on online TV recorder to record TV shows. Those recordings are downloaded as a podcast to iTunes. My following Applescript should just grab those podcasts, update some info fields and finally mark them as "TV show" to have them show up under "TV Shows" in iTunes.
It works very well, only the part where I want to set the video kind to TV show doesn't seem to work.
set video kind of aTrack to TV show

I also had a look at this Doug's script that does something similar and I can't find any difference.
Here is my full script:
on matchRegExp(regex, txt, |caseSensitive?|)
    if |caseSensitive?| then
        set ci to "i"
    else
        set ci to ""
    end if
    set theRubyOneLiner to quote & "s = '" & txt & "'; s =~ /" & regex & "/" & ci & "; puts Regexp.last_match.to_a" & quote
    set theCommand to "ruby -e " & theRubyOneLiner
    set theMatchData to do shell script theCommand
    set tid to AppleScript's text item delimiters
    set AppleScript's text item delimiters to character id 13 -- new line
    set theMatchData to the text items of theMatchData
    set AppleScript's text item delimiters to tid
    theMatchData
end matchRegExp

tell application "iTunes"
    set myLib to library playlist 1

    set pods to every track of library playlist 1 whose genre is "Podcast" and album is "Online Videorecorder"

    set ofi to fixed indexing
    set fixed indexing to true

    with timeout of 3000 seconds
        repeat with aTrack in pods
            set desc to long description of aTrack

            try
                set episode to last item of my matchRegExp("(Folge|Episode) (\\d+)", desc, true)
                set season to last item of my matchRegExp("(Staffel|Season) (\\d+)", desc, true)
            end try

            set series to name of aTrack
            set title to description of aTrack
            set cat to category of aTrack

            try
                set video kind of aTrack to TV show
            on error m
                log m
            end try

            set episode number of aTrack to episode
            set season number of aTrack to season
            set show of aTrack to series
            set episode ID of aTrack to title
            set description of aTrack to desc
        end repeat
    end timeout
    set fixed indexing to ofi

end tell

Answer: The problem is that you can't change the "Media Kind" of a podcast track via AppleScript. For whatever reason, it seems to be some sort of special type that isn't exposed in the AppleScript dictionary.
The closest I've found to a method for doing this is this script in the Apple Support Forums that changes the Media Kind via GUI scripting. It seems to be set up for changing it to an Audiobook, so you'll have to modify it a bit, but it may be a decent starting point.


Is a mirrorless camera OK for macro photography?

Question: For doing macro photography: insects, flowers, etc. is a DSLR camera any better than a mirrorless camera? I have a Fuji X-Pro1. If the DSLR is better--why? If I stick with what I have got what are the disadvantages?
Answer: In terms of sheer image quality, it's highly unlikely you'll find huge and significant differences between an APS-C sensor mirrorless camera and an APS-C dSLR camera. A micro four-thirds camera with its smaller sensor might have an advantage in getting you more depth of field for macro photography.
However, specifically for specializing in macro photography, a dSLR might be a better choice simply because you'll have a few more choices of possible macro lenses you can use, and quite a bit more freedom on choice of flash gear.  Flash can become important with macro photography because depth of field becomes very small, and most shooters counteract that with smaller aperture settings, but that cuts down on the light. And macro photography also magnifies camera shake, so flash and tripods are often typical gear for a dedicated macro shooter.  And there are other possible tools like tilt-shift lenses, bellows, lens reversal rings, cable releases, and wireless shutter remotes, which are easier to source for dSLR mounts (since they're older and have been popular for much longer, the 3rd party support is greater).  Doesn't mean you can't find them for Fuji X, but a few of these may be much harder to find or nonexistent.
In the Fuji X-mount system, there's only a single macro lens: the 60mm f/2.4 Macro. There are also a Zeiss 50mm macro, and a Samyang 100mm macro (basically the same as their dSLR version of the lens), but the selection is relatively limited.
In the Canon EOS mount, however, with an entry-level dSLR body, you'd have a choice of the old discontinued EF 100mm f/2.8 USM Macro, the EF-S 60mm f/2.8 USM Macro, the 100mm f/2.8L IS USM Macro, and the oddball expensive MP-E 65mm f/2.8 1-5x Macro.  Not to mention the Tamron 90mm f/2.8, Sigma's 105mm, 150mm, and 180mm macros, and Tokina's 100 f/2.8 Macro. And also the Zeiss 50mm macro, Zeiss 100mm macro, and Samyang 100mm macro.
And while you could possibly use the same lenses with an adapter, you'd lose autofocus and electronic communication with your camera, and you might not have any aperture control if the lens doesn't have an aperture ring on it.
If the 60mm f/2.8 suits your needs, however, then does it really matter? However, the focal length does determine the working distance which can have an effect depending on how shy your subject is and whether it crawls, hops, or flies away when humans loom over them.  If you shoot mainly flowers, again, does it really matter?
Again, Canon has a wide variety of flash units, including two ring flashes and a TTL-capable wireless flash protocol that's full-featured, robust, and well-supported by 3rd party options. Fuji X, well... not so much. Fuji X doesn't (at the time of this writing) have a Fuji-branded flash that performs HSS. No ring flash option, and no TTL wireless flash protocol that 3rd parties can build on.
That's not to say you can't use an X-Pro1 and stay in the Fuji X camp. It's certainly simpler to use the gear you already own, the colors are amazing, the camera's viewfinder makes the experience of shooting one quite different from a dSLR. And it may take you quite a while to hit one of these gear limits I've mentioned (if you hit one at all). It's just a matter of how far you're prepared to go (and spend) on gear.
Comment: Note that while the macro lineup is almost nothing, Fujifilm does make extension tubes with electronics allowing full autofocus and aperture control. (And they're even reasonably priced for the functionality.) http://www.bhphotovideo.com/c/search?atclk=Brand_Fujifilm&ci=276&N=4077634539+4291439075
Comment: Note that you can always use an adapter to put Canon or Nikon macro lenses onto a mirrorless camera.
Comment: @NayukiMinase I did mention that in the paragraph that begins "And while you could possibly use the same lenses with an adapter..."
Comment: All right. It's an excellent answer overall, and I like the specific lenses and flashes you listed as evidence for your arguments
Comment: @mattdm Ok. Updated by adding the Zeiss and Samyang macro options to both lists. :) Removed extension tubes, after finding out that you can even get 3rd party extension tubes (e.g., Fotodiox) for Fuji X, just like for Canikon.
Answer: Both Mirrorless and DSLR are extremely similar with a few distinguishing functions. See this article about whether a Mirrorless or DSLR is right for you: http://www.tomsguide.com/us/dslr-vs-mirrorless-cameras,news-17736.html
Macro photography is about a lot more than the camera. You also need to think about your light, composition as well as using a macro lens which can focus closer to your subject.
Is it worth the switch? No, not unless you are unhappy with the results your current camera is producing. Instead of switching systems, though, you would be better off making sure you have a high quality macro lens.
Comment: This doesn't answer the question... It alludes to principles vaguely, but doesn't give concrete evidence for the argument.


Applications menu slow

Question: Applications menu loads slowly at first use (first boot). Then, at second use, it responds quickly at scrolling through apps. Is tit a bug or do I have a slow computer? 4 GB RAM, Quad-Core AMD A8-6410 APU with AMD Radeon R5 Graphics. It happened in Freya, too, same PC.
Answer: If other operations are slow then it may be an information bottleneck for your machine. I had a 2011 mac mini with an i5 and 16gb of ram, but the HDD was 5200 RPM and became the bottleneck for that machine. With 20 icons on the desktop and plenty of docs on the desktop, it had a slow initial boot but was fine once everything loaded. I have only deployed Loki on SSD machines with DDR4, some have even been M.2 SSDs, I have never experienced an App menu hang up on them, they are as fast as I expected them to be. Given that you may experience the same behavior in other data-heavy-loading scenarios I think it is safe to say there is a bottleneck for your machine.
Answer: I also noticed it gets slow.
Some facts so far:
1.I tested it on 3 different machines, i3 All-in-One Desktop, i5 Laptop and top-notch i7 Workstation - same deal on all of them - the menu stutters for a second and then works smoothly...untill I launch it couple minutes later after doing something else. The question is, what triggers the stuttering?
2.Tested both on free and proprietary drivers from nvidia - same stuttering.
3.Tested on 3 different resolutions HD, FHD and UHD - same deal.
4.Tested on different hardrives, including SSD's - same deal.
Definatley a software issue.
Still hunting...
EDIT:
One trigger found:
Menu appears to stutter after checking any other place on the wingpanel first (like calendar, volume etc.).
Comment: Seeing the following fix I would recommend compiling the latest version of the applications menu and seeing if that fixes the issue for you.
https://github.com/elementary/applications-menu/pull/48
Comment: Compiling the latest version indeed fixes the problem for me. Now Slingshot handles scrolling between app pages differently.THX!
Comment: Awesome! Hopefully we'll see a release soon.
Answer: It's a known issue: https://github.com/elementary/applications-menu/issues/47
Should have been fixed with: https://github.com/elementary/applications-menu/pull/48
Seeing that the latest applications-menu release was in Sep 26, 2017 this fix hasn't been released yet, see:
https://github.com/elementary/applications-menu/releases
If you can figure out the right repo, it's always interesting to check the existing issues.

Applications menu slow