What is Voice Leading?

Question: In both classical music and jazz, we often encounter the concept of voice leading. What is it?
Answer: The term "voice leading" comes from choral music, but it applies to chord progressions in all sorts of arrangements for all sorts of instruments. A chord progression has two dimensions: horizontal and vertical. Let's say you are playing four-note chords in sequence. You can think of the progression as a series of block chords (vertical), but you can also think of it as four independent musical instruments (horizontal), which play one note at a time, playing four different melodies which line up to make the chords. So voice leading is the process of writing four melodies which are smooth and logical and easy to sing or play, in the service of creating the chord progression.
For example, if you were to compose a melody with a certain chord progression, and arrange three singing voices beneath the melody to flesh out the chords, you would usually not want the melodic lines of the three singing voices to have to jump around across awkward wide intervals from one note to the next. So you would try to follow the rules of voice leading outlined in classical music theory, to produce smooth, musical lines.
Here is a rough example I have created from a Bach chorale.
You might think of this piano part as a series of chords:

However, it is also four melodies sung simultaneously, using voice leading:

Orchestral composers think about voice leading. Pianists who improvise in jazz pay attention to voice leading, which you can think of as how to play a chord progression with the least amount of changes in hand position and the smoothest fingering patterns.
Unfortunately, due to the nature of the relationship of the pitches on the six strings of the guitar, the concept of voice leading is very hard to implement on guitar, and most guitarists don't get around to working with the concept. Guitarists, in contrast to piano players, tend to think of chords as certain block shapes that they memorize, and they give little thought as to creating different inversions and voicings of chords that would create a smoother voice leading in a chord progression.
Comment: As a guitarist, I gotta say I do try to consider voice leading. It ain't always easy, but guys like Johnny Smith, George Van Eps, and Ted Greene laid a pretty solid foundation for the guitar player who wants to think about it that way.
Comment: There might be a couple of mistakes in my chord identification in my Bach example. I was trying to provide a quick illustration, not something rigorous.
Comment: @AaronHipple I second this and would even go so far as to say its easier for me to think about voice leading on guitar than it is on piano, because each string can be conceptualized as a voice. Yes there is a certain memorization when it comes to shapes, but as I've improved I use those shapes more to identify the name of the voice leading progression that I am doing than the other way around.
Answer: Wheat gave a very good explanation of voice leading and I thought I'd just add a bit about counterpoint.
Up until relatively recently (1600s/1700s) the concept of a chord wasn't around - composers may have thrown a C-E-G out there but they didn't refer to it as a 'C Major' chord. However there were certain rules prescribed that told what was legal or illegal as far as voice movement (including valid intervals that could be reached, allowable intervalic jumps, where in the rhythm different intervals could be found, etc) that naturally led to what we now call triads. An excellent book on counterpoint is Fux's Gradus Ad Parnassum - it covers the rules of counter point which I have found very useful to keep as general guide lines in lots of composition and performance situations. Also it's old enough that you can legally download a free PDF (I'm assuming - its a few hundred years old but copyright laws being what they are...)
A great example in how voice leading may be applied is to take the melody that you want to play, the bass line that you would like to play (sometimes derived in real time, sometimes pre-arranged) and fill in the voicings of the chords on the fly. The four basic types of contrapuntal motion are oblique, contrary, similar and parallel motion. using contrary and oblique motion help to set up the independence of voices from one another.
What's really neat about voice leading is that if you follow the voices and not the 'expected' chord patterns you can arrive at some very different sounds than you would have otherwise produced.
A last word on voice leading - inversions win the day! The idea of a chords consonance can be thought of not only in its harmonic context but also in its inversional context - A first or second inversion I chord are a little more dissonant than a root inversion I chord. Thus it is the composers challenge to write his/her piece of music so that the voices naturally reach the inversion that best fits the situation. If at the end of the piece you want to naturally fall into a basic root inversion chord to give a very settled feeling but you have to make some very large vocal jumps to get there or have to move everything up in parallel motion etc, you might want to re-evaluate some of the preceding bars that you have down to see if there is another way to get there.  In the end a piece of music's feeling can be totally altered by good/bad voice leading.
Answer: As Wheat says, voice leading mostly doesn't happen on guitars, but there are a few cases where it does:

descending/ascending bass-lines

using certain patterns, like Travis-picking, the bass-line may be a more or less distinct part throughout the piece.

triad followed by triad+seventh (eg. C / C7 /)
restricting chords to fewer strings to free-up melody strings

As an extreme oversimplification, the classical rules of counterpoint can be summed-up in a single rule: no parallel motion of consonant intervals. Fourths, Fifths and Octaves don't just slide up and down the guitar neck for the next chord change. Rather, one should alternate between different chord forms: the E and A and D all have the same form from the point of view of the figured-bass R-5-8-10-12-15, as do C and G R-3-5-8-10-15. Other inversions help to mix it up, but alternating between the two forms will make a guitar accompaniment more fluid by breaking up the parallel fifths. Conversely, not alternating forms will tend to make the chord transitions more choppy, so to speak, because the parallel motion of fifths violates traditional counterpoint.
Answer: Every instrument that can make a pitch has a voice. Voice Leading is the study of how these voices move, resolve, and fit with the harmony. Every melody, every chord, every harmony can be looked at from a voice leading perspective. How the voice moves, what the range of the voice is, it's function in the harmony, how the voice interacts with the voice are all part of the study.
Classical voice leading is different than Jazz voice leading and so are the rules that govern them. Since Jazz evolved from the classical, I would pick up a music theory book and study classical four part counterpoint and then move on to Jazz. There are many books to this topic and many do and don't that differ from style to style way more than can be written here.
Answer: Voicing leading 101...
Picture a four part choir.  In traditional voice leading you have a few basic rules
1)  The individual singers need to avoid going into each others ranges.  (tenor sings tenor and soprano sings soprano)
2)  The bass sings the root, or the bass of the current inversion (you will often see large leaps here)
3)  The soprano's melodic line should be mostly smooth with the occasional leap.
4)  The tenor and alto will usually end up with kinda simple lines (not really a rule but it usually works out this way)
5)  If two voices are separated by a fifth in one chord those same voices shouldn't be separated by a fifth again in the next chord.  (this mean you are going to have to invert frequestly)
6)  If two voices are separated by an octave in one chord those same voices shouldn't be separated by an octave again in the next chord.  (As you add more voices this becomes harder and harder)
The guitar cant really do this well when playing all the parts on its own on all six strings because the the bass note should be moving 4 to 12 frets and the soprano note should be moving 4 or fewer.  If the guitarist lets the bassist handle the bass note and plays chords with as few notes as possible proper classical voice leading is achievable.
So the long and the short of it is if you want to voice lead abandon the playing 5 and six string barre chords and try playing simpler 3 or 4 note chord voicing.  If done properly the top note of each chord should form a pleasing melody and not just a random flow of notes.
Side note,  funk and disco guitar parts often have solid voice leading.

What is Voice Leading?


What is the simplest way to represent this situation mathematically?

Question: Sitting in my room with two large jars full of green tea and black coffee, I suddenly realized that I would not be able to drink the coffee first. That is because I only regularly drink out of one of the jars. Yet I also realized that, without a third jar, I would not be able to move all of the contents of jar 1 into jar 2. As such, it seemed like there was something universal about the fact that, given two full jars, the contents of one cannot be poured into the other without the existence of a third jar. I suddenly found myself wanting a mathematical abstraction that could represent this situation. But I have no idea how a set could be called 'full.' I suppose there is some set-theoretic mathematical structure that can have this property though, right?
Comment: Sound like Towers of Hanoi. Or variable [swap](http://en.wikipedia.org/wiki/Swap_%28computer_science%29); too bad you can't `xor` your mugs!
Comment: Also sounds Pigeonhole principle-ish.
Comment: I'm not really sure about set theoretic, more of a combinatorical nature perhaps. In set theory it is the content of the jar that matters; not its name. So without loss of generality just swap the labels and get it over with.
Comment: Why is this question down voted? Seems to be a sensible question.
Comment: If it were a jar of water and a jar of sugar, you might be able to pour the contents of one into the other...
Answer: If you have just two jars, then you can move all the contents of jar 1 into jar 2 - it's just that you either then have a mixture you don't want, or the contents of jar 1 "on top" so that when you transfer back to jar 1 it is the stuff which was already in jar 1 which goes in first. So Jar 1 is always empty or contains some of its original contents, and similarly with jar 2 - so you can't do the swap.
If the contents of the jars mix, then you need one empty jar (however many jars you have which are originally full), and it is then easy to achieve any permutation of contents you want across any finite number of jars.
If the contents of the jars don't mix, but the "poured in" contents stay "on top" and come out first, then you can achieve any permutation you wish provided there are at least three jars. To transpose the contents of A and B, pour the contents of A into a third jar C (which exists by hypothesis), then the contents of B into A, then the top half of C (original contents of A) into B. Since any permutation is a product of transpositions, any permutation can be achieved.
It was not quite clear which case you were considering, but I hope this helps.
Comment: It may be different with liquids which don't mix - (light) oil and water, for example. Pour the water carefully into the oil, and then decant the oil off the top.


Is is possible to make popped potatoes?

Question: Many grains (and some starchy non-grains) can be popped or puffed.  Corn can be turned into popcorn, rice into puffed rice, etc.  (http://en.wikipedia.org/wiki/Puffed_grain)
Can potatoes be popped/puffed?
Comment: exploding tater in a microwave count?
Answer: The reason popcorn can be popped is that they have a water-impermeable hull, which contains the pressure of the steam created inside the kernel as it is heated, until it passes a critical point.  When that happens, the steam explodes out, breaking the hull, and creating the popcorn.  Some of the other puffed products are more complex, as the link you have already found shows.
Potatoes do not have a water impermeable skin, and so cannot be puffed in the same manner as popcorn.
There is a dish—sometimes called puffed potatoes—where the steam inside fried potato pieces is used to puff them up, but it will not be similar in texture to puffed grain.  See this recipe, for example.  They will be more akin to fluffy french fries (or chips, as they say in Britain).
There is another dish called puffed potatoes, which are essentially a choux paste with potatoes that are baked or deep fried.  They are a great dish, but are a different type of thing entirely. See this recipe from the great Jacques Pepin.
Answer: The process for making most puffed products (except popcorn, which SAJ14SAJ has explained) isn't something you can do easily at home. As the link you included says, the grains are placed under high pressure with steam, then the pressure is suddenly released. This takes some specialized equipment. You can get the pressure and steam part at home with a pressure cooker, but they're designed to never release the pressure quickly, so you can't actually pop anything.
So should you have the right equipment, you can make puffed potato products. The example I've seen is Popchips. They're made with a similar process, popping something made from potato flour under high pressure. I'm sure there are other examples out there, but they're all going to be things you can't really do at home.
All this said, I do wonder if there's a way you can do something like muri (Indian puffed rice) except with globs of potato starch. It's still not an easy task, though. The rice is tossed into a sand-filled pot or oven; the sand holds enough heat to rapidly heat the rice so that the escaping steam puffs it. My guess would be that if you can get bits of potato-stuff to about the consistency of the soaked rice, it'd work, since both rice and potatoes work with the industrial process. But it's still an ambitious project to try at home. Perhaps some of our Indian users could provide some more advice!
Comment: I am sure the same method used to make Cheetos would work, but definitely requires industrial equipment :-)
Answer: To puff starches you have to cook them in water until very soft, then dry them completely and after that you can deep fry and puff them. I have not tried this with potatoes, only with pasta where it does work nicely. And you can do the same thing with proteins like bacon rind - just find a recipe for chicharrones (sp?).
If you have a dehydrator you can try to cook potato slices, dehydrate and then deep fry them. Without dehydrator the potatoes might go bad before they dry out. The puffing usually also works in the microwave, but without fat the potato is probably bland. And make sure to tell us the result!
PS: ever tried to put parmesan rind (well dried out) into your microwave?
Comment: Chicharrones is the correct spelling, but its meaning varies widely with geography, which is worth bearing in mind when looking for recipes.

Is is possible to make popped potatoes?


Can I install a replacement faucet directly onto a laminate countertop?

Question: I am updating my wet bar area with a new sink and faucet.  Can I install the new
faucet directly onto the laminate countertop so that I can use a separate no-hole sink?
Answer: Sure you can.  I'd recommend using a sharp Forsner type drill bit or sharp hole saw to avoid chipping the laminate. Cover the laminate with painter's tape and mark your hole centers.  If your using a single 4" faucet fixture, use a template to drill the holes. If you are using separate handles/neck. the common spacing is 8 inches, but again, use the template.
Comment: Does the wood surface need to be prepared at all after the hole is cut?
Answer: Yes, you can install the faucet directly into the laminate countertop. I wouldn't use an under-mount sink with a laminate countertop, because the corners in a laminate countertop are weak points. But a separate faucet with a self-rimming sink should be fine.


How could Slick betray the Jedi?

Question: In the early episode "The Hidden Enemy", the clone trooper Slick, spies on the Army of the Republic, using the justification that his brothers were "cannon fodder", while the Jedi easily survived battles.
However, this seems to contradict "Attack of the Clones". The Kaminoans tell Obi-Wan that the clones are completely obedient.
Comment: Not really fleshed out as an in-universe answer, but complete obedience is not a thing people can guarantee, from other people, it's just not how people-ness works.  With that in mind, I'd guess they were... well, advertising...I mean basically overselling their "product" and not minding inaccuracies in what is, to them, a business deal.
Comment: Yes, I know the clones questioned orders in the Umbara arc. However, in that instance, the clones eventually discovered they were fighting each other.
Comment: Perhaps he had a malfunction with his inhibitor chip or some other defect in the cloning process.
Answer: Well, you are right, clones in Clone Wars cartoon are different then clones in the movies. In the movies we don't see them as anything more then "human droids" , they simply follow orders without sense of wrong or right. For  Clone Wars they have been completely humanized- they have their own individual personalities, emotions and opinions. For example, Slick did what he did because he considered Jedi incompetent military commanders (which is true, because they didn't have the training or experience in military matters). To explain the clones' blind obedience in carrying out Order 66, Inhibitor chips were introduced.
What about complete obedience promised by Kaminoans? In universe, this could be explained by the fact that Kaminoans never had a project of this size before, and considered clone troopers as the pinnacle of their achievement, yet they were too aloft to consider that their "work" could somehow become independent from them. This was shown in episode Conspiracy and Fugitive, where Kaminoans clearly state that clones "belong to them", i.e only they understand their behavior.

How could Slick betray the Jedi?


Why is my booster fan pulling cold air from outside?

Question: This is my first winter in a house with an oil-heated, forced air system. I noticed my wall vents were pushing out warm air, but the floor cold air return vents were pushing out cool air. I followed all the ducts and found a booster fan pulling cold air from the outside, and pumping it into the ducts. I covered the outside hole with a piece of rigid insulation, and that has stopped the fan from turning on, and the cool air from coming up my vents. (they do suck cool air into the furnace) Did the previous owners make a mistake, or am I missing something?
Answer: It would appear to be a poorly tuned fresh air vent (aka a "Make-up Air vent")
Blocking it completely is not a good choice.
Tuning it correctly is a good choice.
The intake should not be bringing in more air than the furnace blows out (far less, in general)
A page from 11 years ago...
http://www.nchh.org/Portals/0/Contents/Read_This_Before_You_Ventilate.pdf
Answer: it sounds like somebody might have jury rigged something.  older or malfunctioning oil furnaces have been known to "soot" the warm side if the supply air to the burner is too warm.  the booster might have been installed to cool the supply side air.  however, you should never have air coming out of your cold air returns.  it is by design a suction port, not an exhaust port.


What happens to a star after it has become a red giant?

Question: When our sun reaches the end of its lifetime , it will turn into a red giant. How long will it be a red giant, and what happens after a star has been a red giant? Does it turn into a planet after a long enough time spent, when it has used up all its helium?
Comment: No, the Sun will not turn into a red dwarf. Red dwarf stars theoretically will cool down over time -- but none have yet done so because they do so over a time span longer than the current age of the Universe.
Comment: You might want to update your title and question, changing "red dwarf" to "red giant".
Answer: It will become a planetary nebula like e.g. the Cat's Eye nebula that was formed by the death of a star with about the same mass as the Sun ~ $1\ M_\odot $:

              Composite image using optical images from the HST and X-ray data from the Chandra X-ray Observatory
The Sun, and any red dwarfs above about 0.25 solar masses, will expand into what's called a red giant, a late stage of stellar evolution. At this stage, the star starts to fuse different elements, and eventually throws off its layers as a planetary nebula, leaving behind a white dwarf made of carbon and oxygen.
A red dwarf that is too small to become a red giant will not turn into a planetary nebula: its fusion processes will eventually cease and it will probably produce a white dwarf made mostly of helium. But the main-sequence lifetime of these very small stars is longer than the age of the universe, so this has never actually happened yet. The helium white dwarfs that do exist were formed in binary star systems (and were formed during their complex dynamics).
Red dwarfs are small main sequence stars - the smallest and dimmest that are still able to fuse hydrogen in their core. Brown dwarfs are even smaller (in terms of mass), but cannot even fuse hydrogen - they are thought to be able to fuse deuterium and lithium. Stars smaller than a brown dwarf turn out to be gas giants like our Jupiter, Saturn, Uranus and Neptune.


Offline defragmentation of Exchange 2003 mail store

Question: What is the best way to run offline defragmentation of Exchange 2003 mail store if you don't have enough disk space on the server. Can you attach an external drive and store the temporary defrag file and then just copy the defrag file to the path where the database is located.
Answer: You can redirect the temporary files to another drive using the /T option, or indeed if you really have to you can actually take the database files (you want the EDB and STM files) and the ESEUTIL tool and run it on another box which does not even have Exchange on. Obviously transferring everything all takes time while Exchange is offline, so this is a last resort.
How to run Eseutil on a computer without Exchange Server
How much free (white) space do you have in the database? The online tools are pretty efficient normally unless you have done a big bunch of mailbox move or delete operations.
Comment: Unless you have gobs of whitespace I wouldn't worry about an offline defrag.
Answer: Another option because defrags can be a little scary - just create another database and move all the mailboxes to it. You then don't have a big long outage for everyone and there's very little risk. You now have a shiny new database without too much defragmentation.
Comment: You lose single-instance storage when you do this. Depending on your data this may result in a larger database at the end of the process


Marathon training plan for my level of fitness?

Question: I ran 12.5 miles at 1:40. I swim and gym regularly, and go for a 6 mile jog 4 times a week. I've got all the free time in the world. What should i use?
Answer: I agree with @jsmith but all the plans tend to follow a few specific guidelines. Here are the ones I'm following:

Build up to at least 20 miles 1-2 months before a marathon race.
Run all long runs ( +16 miles) at an easy pace.
Do one long run every week but run your longest long runs every other weekend at the most.
Aside from running for distance for the longer runs; run to time.
Running more than 3 hours during training is treading a fine line between fitness and injury so most people advise against it.
Run 30-60 minutes 2-5 times every week.
One day every week should be devoted to speed work like sprinting.
3-4 months before marathon race focus starts on speed (and 180 spm cadence).
Taper 2-3 weeks before race by cutting down distance but keep pace and intensity the same (until the last 4-5 days?).
Listen to your body dont push too hard by taking a day off and take advantage of itches to go further or faster.

If your not cheap like me then get with a coach or a local running club. Alot of people get into clubs and they sound like fun...
Comment: Running clubs sound like the best way to pick up. Thanks m8
Answer: It sounds like you have a good aerobic base to start a marathon training plan now. You are running around 25 miles per week, which is right at the required base miles to start a running marathon program.
There are A LOT of options out there for marathon programs. But I'll give you my 2 cents as to which I have liked the best. For price and quality I don't know if you can beat marathon training academy's programs. They also have a nice podcast you can listen to with great running tips and racing advice.
McMillan running has recently partnered with Strava and allows you to build a program through them if you are a premium member (this is a very good option for existing premimum strava members). This also gives you the benefit of logging your miles through strava, which I really enjoy!
Ultimately there are quite a few good options out there. I would avoid any that never have you run at least 20 miles... The ones that avoid those long grueling sessions tend to be geared towards people who want to complete a marathon, but not run one fully (based on your base miles I feel like you are in the ladder category).
If this is your first marathon, keep in mind that your goals should be pretty realistic. No matter what program you pick your first marathon is more about running it completely, and getting the experience. If you enjoy it, you'll want to do it again, and you can adapt your training based on what you learned!
Good luck!! And as a side note, I'm not affiliated with either of the companies I suggested. I have just had good results with both!
Addition based on comment
I've only ever looked at a few free marathon training programs, but never used one. So I can't fully back one. That being said, just from viewing them they seem to be built on very similar principles, and likely will yield good results. You learn A LOT from your first program... A lot about yourself, and even the workouts that benefit you during different situations. I don't think it's a bad idea to go with a free one, and then possibly take notes and adjust based on your experience...
On a side note. I actually think to get the absolute best results you need a coach. They are able to see and point out things you can't. A good coach is honestly much more valuable than any training plan because they can adapt based on how your body is responding...
Comment: Thanks. Is the difference night and day between the paid for plans and the free ones?
Comment: @ErljaJkdf. I dont know but the coach would be invaluable to save time. If I wasnt so cheap Id be faster right now!


HVAC blower fan won't stop

Question: FINAL UPDATE: I have found the culprit - the Nest thermostat itself. First, I disconnected the t'stat at the control panel and found out that the fan would no longer start upon powering the system. Then I replaced Nest with the old 'dumb' t'stat (from 4 years ago), and everything works fine now. Now I will try to figure out what happened to Nest: failure, software update, etc., but that's another topic.
So I had this problem with my HVAC during winter when out of blue (after working fine for many years) the blower (fan) wouldn't stop, even after the temperature reached the target and the burners shut off. The burners would start and stop per thermostat instructions, it's just that the blower motor wouldn't stop to run. The only way to stop the motor was to power off the entire HVAC system. Mere switching the mode to OFF in thermostat wouldn't stop it.
I kind of half-solved the issue then by disconnecting the G wire from my thermostat (Nest 1st Gen, see picture below). As a result, the heating mode worked fine and controlled the blower as it was supposed to. I couldn't manually control the blower from my thermostat, but it wasn't a problem for me, so I never got to the bottom of this.
Now, it's time to use A/C, and this half-solution backfired. When I now set Nest to cool, the outside fan/compressor starts working, but the blower motor in the basement doesn't start. If I connect the G wire back in Nest, the blower does start immediately after powering HVAC without any command (similar situation as in winter), the cool air blows fine, but again the blower wouldn't stop after the desired low temp is reached. The difference now is that the cooling mode doesn't seem to be able to control the blower correctly (or at all) as the heating mode does.
I have visually inspected the system, cleaned wire ends and tightened the screws.
Any ideas what exactly could be wrong and how to fix it? I can provide more info on the system if necessary. Thank you!
UPDATE 06/06/2019: Got back to this after travel. Since running a new t'stat wire didn't look very practical in my set up, first I decided to inspect the wiring and found a lot of splicing. I added a picture of a big splicing hub that could explain the color mismatch for wires: HVAC's Green wire becomes Yellow on t'stat, Red becomes Black. White is White (although a bit yellowish due to age). But I am confused about where the Blue wire at t'stat comes from. I can see the Blue wire from HVAC going towards the outdoor compressor, but how it ends up in t'stat I don't know. Unfortunately, I am not able to follow the cables to t'stat for the whole length due to basement ceiling.
Still looking for any ideas on why my fan suddenly started blowing without stopping and how to solve this. Thank you!
Comment: The G wire is on the G terminal in the unit but the yellow wire is hooked to the G terminal on the Nest.
Answer: Is there a splice in your T'stat wiring? Your color scheme is not matching up. Also you've landed a wire in your t'stat on your "Y" terminal but it is not landed on your power source and the "C" is landed on you power source and is not mounted on you T'stat.
I would suggest you run a completely new thermostat wire and reconnect matching color and code.
Comment: This is fubar, +1
Comment: Yeah, look for where the AC wire is spliced in and to take a picture of that.
Comment: Thank you! Running a new thermostat wire is now definitely on my to-do-list
Comment: When I looked at the power source for the 1st time ever in February, the discrepancy in wire colors surprised me too. But I wonder then how the system had worked fine for 3 or 4 years since I replaced the old t'stat with Nest? Something should have happened to trigger the problem. The splice (if there is one) became loose or shorted?
Comment: Updated my post with a splicing picture and additional findings.
Answer: Go to this link, this is how Airwave technology of Nest works. Even if it attains the desired cool temperature. The blower still runs causing that noise (though the compressor turns off by itself). I was also so much concerned about the fan not turning off or the HVAC not turning off until I read this article..
https://www.onehoursmarthome.com/blog/nest-airwave
Thanks
Hari
Comment: Hello, and welcome to Home Improvement. This is interesting, but doesn't answer the original question. Please [take our tour](//diy.stackexchange.com/tour) so you'll know how best to contribute here.

HVAC blower fan won't stop


Buying Electric guitar

Question: I have been playing an acoustic guitar for 3 years. Now I want to try my hands on electric guitar and I am going to buy an electric guitar soon. My budget is 200 to 300 usd. My question is what things we must consider while selecting the guitar so that we come out with the best guitar from the shop?
Comment: Don't buy anything online is my advice to you, touch it, hear it and decide in a shop if you will be able to live with the instrument
Answer: From my personal experience:

Look at different guitars and select a shape that you like.
2a. Ask who the manufacturer is!
2b. Take it into your hands, hold it a while and feel its weight and shape. Do you like it?
Play a little and see if it sounds okay. Play different things. Try slides and most certainly play in all positions on all strings. See if your hand is comfy.
Ask someone to connect it to an amplifier. Keep playing.
Ask for its parameters and read them.
If you like it, buy it, else go to step 1 and repeat.

P.s. There is no best guitar, all guitars are different, but some can be cheap in quality and sound. Try different guitars on one amp with one setting. Search for second-hand guitars, you might find a good one, a store isn't the only place you can find a guitar in.
Comment: Not worth a separate answer, but might be worth adding to yours. Check out used models too - many a bargain to be had. Though last time I did that I ended up with a '64 daphne blue Strat... not exactly the 300 buck bargain I'd set out for ;)
Answer: If you have a guitar teacher or friend who plays electric a lot (not just a school kid who can manage 'Stairway to Heaven'), take them with you. Two sets of eyes are better than one.
You're going to need an amp, tuner and a cable as well. You may find a bundle deal that throws everything in for you. Test every guitar through the same amp, and don't have the distortion or reverb switched on all the time - you want to hear the guitar.
When testing the guitar, play every string at every fret (even the dusty ones above 12th fret). You're not playing a tune, you're looking for buzzes. If you get any, look for another guitar, or (if you really like the guitar) get the store tech to fix the problem for free.
Check that the neck is straight. The guitar tech in the store will be able to test that for you, but looking down the fingerboard will reveal any major problems.
Make sure there are no crackles when you use any rotary controls on the guitar.
Look for a low action. Action is generally a preference thing, but a lower action will be easier on fingers. Electrics are usually lower action and lighter strings than acoustics.
Check that there are no missing screws on the scratchplate, bridge, tuners, back of the guitar, etc. A missing screw indicates that someone has messed with the guitar badly (a decent tech won't lose a screw...)
Check that the tuners are smooth and not loose.
Buy a new set of strings (or negotiate them into the deal) with the guitar; you don't know how long the ones on it have been there, and good strings make a decent guitar sing.
Don't go over budget. Consider used guitars (always try for a deep discount), and accept that after a year playing electric, you'll probably feel the need to upgrade.
Answer: We have some guidlines here
Quite important is to choose guitar with right pickups There is broad choice of mixed pickups guitar and vanilla ones. Guitar with one type of pickup will be more specialized while more types of pickups will give more varied sounds. It is possible to change pickups but exchange cost may overcome beginners guitar.
Also there are different preferences about bridge:
Hard tail -- easy to set up and change tuning but no Vibrato arm
Movable bridge -- different types of bridges vary in vibrato effect range and how complicated setup is. It is possible to block it if it causes problems.

Buying Electric guitar


When back country camping, how do you avoid being attacked by a mountain lion in your sleep?

Question: I'm looking to camp in SE Oregon. At minimum, my girlfriend and I will have sleeping bags. We're open to adding a tent, fire, and other stuff as recommended. Our goal is to be able to hike around lightly and sleep without worry of being eaten by a mountain lion (cougar/puma/panther/catamount).
Comment: Does XKCD 795 apply? https://xkcd.com/795/
Comment: My own method is the same one I use to avoid getting hit by meteors :-)  I live (and hike, camp, ride horses &c) in the natural habitat of mountain lions, and have seen exactly one in 40-some years - and that was just a brief glimpse of it's rear, as it was leaving quite quickly.
Comment: You should be careful: There are a lot of ways to get seriously injured or killed when camping, and if your focus is on a random thing like mountain lions with a virtually 0% chance of happening, then that could be a red flag that you're focused on the wrong things and not taking care to be prepared for more realistic dangers, like weather, trips/falls, camp fire burns, poisonous plants, accidentally getting shot (it's cougar hunting season, and the hunters are a far higher risk to you than the cougars), head injuries, drowning, broken bones, even a car accident on the way there.
Comment: The cougar- human interactions I have heard of are all moving hikers, likely being mistaken for deer or other wild prey. Sleeping humans will give the cougar more time to realize the mistaken identity and leave.
Comment: Cleaning up a bunch of comments here, from attempts to answer, to jokes about the wording etc. Please all remember that if you have an answer, use an answer post, not a comment as it just leads to noise!
Comment: I just thought I would add this here. This happened a few days ago in my backyard. https://youtu.be/krQZYBtxWsw
Comment: @Charlie Brumbaugh One official site says that food left out attracts raccoons and rodents, which are prey of cougar.  So it is a second-hand attraction.  The site said to double bag food in heavy plastic bags as a precaution against cougars.  So bear canisters may be overkill wrt cougars.  But if the OP is in bear country, then he needs bear canisters anyway.   See [Living with Wildlife: Cougars](http://wdfw.wa.gov/living/cougars.html) for double plastic bagging, and, deep into the article, about predators following prey (raccoons etc)
Comment: What about a tree tent?
Comment: The tent is more likely to make a difference by keeping out rain, spiders, snakes, lizards, and other things that sometimes startle folks.
Comment: I would sleep in a tent. It would make the mtn lion confused.  Wear your headlamp and look around before crouching, sitting.  They have yellow eyeshine.  I had to scare-off a mountain lion one time, camping solo in a forest about 6 miles from the nearest road.  It was a pretty damn nerve-wracking experience.  It was standing there staring at me about 40 feet away.  I growled at it very loudly and shouted a bunch, trying not to sound afraid.  It eventually left.  Footprints all around next morning.
Answer: If one looks at the list on Wikipedia of fatal attacks, one will notice that fatal cougar attacks are pretty rare.

At least 20 people in North America were killed by cougars between 1890 and 2011, including six in California.
Children are particularly vulnerable. The majority of the child victims listed here were not accompanied by adults.

So just by being adults and there being two of you, you have a reduced chance of being attacked.
Just seeing a mountain lion is a rare occurrence.

Oregon is home to more than 5,000 cougars, or mountain lions. While cougar sightings and encounters are rare, it is wise to educate yourself about the big cats.
Native to Oregon, cougars range throughout the state, the highest densities occur in the Blue Mountains in the northeastern part of the state and in the southwestern Cascade Mountains .

Source
It also looks like they are hunted in Oregon, this will be in your favor because the mountain lions will be afraid of getting shot at by humans and therefore avoid them (This is certainly true of coyotes in Wyoming).
I don't think a tent would do you any good and a fire would probably require tending. You could take turns staying up and standing guard, but that would get exhausting.
It's one of those things where you have to balance the unlikeliness of it happening with the effort required to try to prevent it. After all part of being in the wilderness is the risk/danger and there is no way to rule out all of the possible misfortunes.
As a personal anecdote I worked at Summit Adventure for a couple of summers. It has been around for more than forty years and the summer staff has always slept outside under the stars on wooden platforms. It seemed like multiple times per summer the mountain lions would come down towards the lake at night and scream. This has happened for as long as it has been around.
Other than freaking people out, no one was ever injured and I don't think anybody ever saw one.
Personally, I just slept through it.
Comment: Maybe it's just me, but I don't want to be attacked non-fatally, either.
Comment: Fatal attacks may be rare, but what about people sleeping outside in cougar country? If that is also rare, then your statistic is less relevant. Maybe they are rare _because_ everybody who sleeps outside in cougar country takes good precautions like OP is asking about.
Comment: @RemcoGerlich,  literally millions of people camp outside in these areas each year without taking any particular precautions against cougars. Bears are another matter. Except in very exceptional cases cougars are very shy of human contact. Ironically, despite living in an area where cougars are relatively common, I never saw one in the wild until I visited Patagonia.
Comment: @KenGraham A statement that studies have proven is not really proof.
Comment: Studies have proven that [sport hunting](http://www.catamountcreek.com/faq/) of cougars does not increase human safety.
Comment: @RemcoGerlich Plausable, but the statistics are so tiny that I don't think that could play a major part. With 0.165 people getting killed by cougars every year, out of all the people who go hiking, either common sense is more than sufficient for proper sleeping protection, or no sleeping protection is needed.  Shark attacks only kill 0.5 people per year, for a point of reference.
Comment: "It's one of those things where you have to balance the unlikeliness of it happening with the effort required to try to prevent it." Risks need to be weighed up in terms of both probability and severity of occurrence. Here, we have an event that is _extremely_ severe, so the argument needs to be that the probability of occurrence is so low that even that even these severe consequences can be accepted.
Comment: I wonder what distance a careful drive to/from the trailhead would constitute a statistically equivalent risk?
Comment: Not dying is for sure a great outcome. But I'd still hope for a better - like not being non-fatally mauled, bitten, etc.
Answer: Since 2000 there are only 3 recorded death by cougar in North America and all of those were day time.   wiki
Cougar attacks are up but still rare on the west coast.  Up in CA as partly because cougar hunting is not allowed and the numbers are climbing.  In OR and WA dogs cannot be used to hunt cougar. According to the link below since 1990 10 non-fatal attacks and 3 fatal attacks have occurred in CA.
Does Oregon Have A Cougar Problem
As for precaution I would not camp with a small lamb as bait.  Other than that seal up your food and store it way from the main camp.  They have a much higher leap (vertical) compared to bears so would need to go much higher than a regular bear bag and they are very good climbers.
Pepper / bear spray is reported to be effective.
Nathan added a very good point in they are very good hunters.  Attacks are very, very, very, rare but if you are attacked there is a good chance you won't even see it coming.
You could drop a cougar with a hand gun in the rare, rare, chance one does decide to attack they will close quickly and you would need to be pretty darn good with a gun.  I would go with pepper spray.
I was raised in WA and never saw a cougar but I did see one in Big Bend National park. He / she looked right at me and kept on walking.  I was not concerned.
Comment: Given those statistics, driving in a car to the trailhead seems like a far more dangerous risk than cougars. Or staying home to [take a bath](http://danger.mongabay.com/injury_death.htm) (killing 341 people in the year 2000).
Comment: Also stay away from [KILLER VENDING MACHINES](http://urbanlegends.about.com/b/2005/06/29/are-vending-machines-deadlier-than-sharks-repost.htm) which claim the lives of 2-3 people every year. (The key is identifying the ones that kill people and stay away from them. Also don't rock them, because they will fall over on you and they get up really, really slowly.)
Comment: I'm pretty sure that the vending machines only killed people who were rocking the machines. So, a good comparison if you're the kind of person who rocks cougars. ;)
Comment: @corsiKa [Are Americans more likely to be killed by vending machines than terrorist refugees?](https://skeptics.stackexchange.com/q/37000/2004) on [skeptics.se] appears relevant.
Comment: You need to update your count [Cougar shot dead after killing US cyclist and mauling another](http://www.bbc.com/news/world-us-canada-44186998)
Answer: Cougars principally hunt at dawn and dusk. If you're small, don't be alone at those times of day. Regular sized adults are generally too big for a cougar to consider as prey.
Avoid animal carcasses. Assume there is a carcass if there are lots of scavenger birds somewhere.
Of course, take standard precautions with food: Keep food odors off your sleeping bags and other night gear, and hang the food itself in a bear bag away from your sleeping site before bed.
We say "bear bag" because it sounds good, but to be honest, the problem is usually things like raccoons and skunks, not things like bears and cougars.
In the super unlikely event that you do encounter a cougar and the even less likely event that it sticks around, maintain eye contact. Cougars like to ambush from behind, so if they know you see them, they usually just chalk up a loss and move on. You can add to your cougar repelling power by standing up tall, holding a jacket in the air or just raising your arms, showing your teeth, and yelling, but eye contact is the main thing.
You'll be fine. No need for an overnight fire; no particular anti-wildlife benefits to a tent. Being attacked by a cougar in your sleep is like being crushed by a falling tree in your sleep: Once you've taken a couple sensible precautions, you can put it from your mind and rest easy.
Comment: ...or bring a laser pointer and go for the diversion tactic.
Comment: Addendum: If you've ever played laser with a cat, you know a fleeing target is hard to resist. So don't go running during twilight hours either.
Comment: Now I'm worried about being crushed by a falling tree. :(
Comment: "We say "bear bag" because it sounds good, but to be honest, the problem is usually things like raccoons and skunks..." I find it's chimpunks and squirrels, that are even more common and can also do damage to gear.
Comment: Good point if they do plan to attack you then you are not likely to see them.  +1
Answer: I was backpacking with my nine-year-old daughter two years ago in Oregon near Mt. Hood. I awoke (in our tent) to the noise of a cougar walking around outside.  I assumed it was a black bear and didn't learn otherwise until we found its tracks the next morning.
Anyway, I made noise by running my fingers over the nylon tent fabric.  It was pretty loud, and the "bear" ran off through the underbrush.  Made really good time for a bear, too!  However, unlike a bear, the cat came back (at least) twice more that same night.  Each time, I scared it off with the same noise, without leaving my tent.  We were there for two more nights, but the cat didn't visit us again.
We had our food hanging from a tree, out of reach.  The rest of our gear was in the tent with us.
Seeing how it behaved, I think there is no chance at all of one coming into a tent.  The strangeness, the noise, and the uncertainty would all keep the cat away.  But I certainly wouldn't feel comfortable sleeping around cougars without a tent.
I did a lot of research after we got home. Here's what I found out:

Cougars are very seldom seen.  And they Almost NeverTM attack people.
Cougars generally attack their prey from behind. They will wait, sometimes on a rock or in a tree, until their prey passes by, and then leap on them, grabbing for the neck.
In the vanishingly few times humans are attacked, it is usually children or small adolescents as the targets
Unlike with bears, if you are confronted you want to be intimidating and aggressive. Look directly them. Wave your arms, yell, move back and forth, throw rocks. They don't like to fight their food! Don't try to stand still in a menacing fashion; it won't impress them.
In the (few) examples of an adult actually getting attacked, most were able to drive the cat away by punching/kicking/fighting.

In summary, they like to lay in wait for their prey and take it unawares. And they like easy prey. Most hikers simply don't worry about them, and most people never see one.
Of course, I saw no references at all to being attacked while sleeping!  Hence my personal preference to use a tent :)
Back to my own exciting story, here's something that I didn't expect: the cougar raked pine needles and leaves over the ground where we had peed!  Maybe it left some of its own urine there, too, but I didn't think to smell around :)
Comment: Cougars attack the back of the neck because, like domestic cats, they kill by spinal paralysis. Their canine teeth slip between the vertebrae and sever the spinal cord.

By contrast, cheetahs take the front of the neck in a suffocating bite. Their bone structure and muscles are too light for a reliable spinal bite. On the other end of the spectrum, jaguars have huge strong heads that allow them to bite right through turtle shells and prey skulls. But I think most cats use the spinal bite on whatever size prey they match.
Comment: @williamgrobman, I've added more information to my answer. Please take a look!  And have a nice camping trip :)
Comment: A friend was walking down a trail and saw a cougar approaching from the opposite direction. He tried  the "intimidating and aggressive" thing, but it kept coming. He shot it (he was deer hunting). He was worried that he would be in trouble for an illegal kill, but when he reported it, they said "I can't believe you let it get that close. It was within pouncing distance". Turns out there were two kits up a tree that he was heading towards. Sad.
Answer: Cougars are as one would expect not afraid of any animal, being on the top of the food chain. Their one exception would be bears. Not even hunting or other disposal means will deter cougars from attacking people.

Killing cougars does nothing to prevent future cougar attacks or make people and livestock safer; however, employing common sense precautions makes all the difference.
Studies have proven that sport hunting does not increase human safety.

Here are some common sense things one might want to keep in mind while camping in cougar territory.

Bring along a whistle or an air horn that could help scare away wild animals you may encounter.
Store foods stuffs and trash away from your campsite using some bear proof methods most commonly used by hikers and hunters.
Do not set up camp in an area with fresh cougar tracks or scat.
Hike (and camp) with a friend. Attacks are less likely in a group.

Cougars are crepuscular animals (active primarily during twilight), but will look for prey at anytime of the day also. Some sources claim that cougars are mostly in search for their prey between 5:00 am and 7:00 am, and between 6:00 pm and 8:00 pm. They usually wander during the day and they sleep at night. These are usually the times that the deer are most active. This makes sense to some degree, so I would keep an extra vigilance during these times.
I truly doubt that people camping in a group (two or more together) would encounter a cougar at all at night while camping. Please allow me to add my two bits of ideas here:

Keep a fire going during the night. Sources can neither affirm or deny the possibility that a campfire would detour a cougar. But at least you will have more light and warmth around you also.
Keep a large stick and or knife close at hand for the unexpected. Just the fact that there are two of you camping together, I doubt this measure would be needed.
Since the big cats do not like groups of people or noise, you might consider taking a radio along with you while camping. Make sure to take advantage of it (if you can get reception) during the hours of dusk and dawn.
Comment: I find it hard to trust an answer which says "Cougars are nocturnal animals. [...] they sleep at night."
Comment: I think both of your sources about hunting are heavily biased.
Comment: Also see this [book](http://www.goodreads.com/book/show/103071.The_Beast_in_the_Garden)
Answer: This source, List of fatal cougar attacks in North America suggests that you are probably safest from a cougar while sleeping.
Of the seven adults killed by cougars in North America from 1990 through mid-2008, five were jogging, hiking, biking or skiing.  One was killed defending her six year old son on a horseback trip.  The body of the seventh was found near his mobile home.  During this period, two children were killed by cougars, and five children in the 1970s and 1980s.  No adults were reported killed by cougars in the 1970s and 1980s.
The source also lists fatal cougar attacks from the beginning of the 20th century, but a list from these early years may not be complete.
Living with Wildlife: Cougars by the Washington Department of Fish and Wildlife has this to say about camping in cougar country (emphasis added):

1.Hike in small groups and make enough noise to avoid surprising a cougar.
2.Keep your camp clean and store food and garbage in double plastic bags.
3.Keep small children close to the group, preferably in plain sight just ahead of you.
4.Do not approach dead animals, especially deer or elk; they could have been cougar prey left for a later meal.

Number 2 is the one pertinent to your question.  Earlier, in a comment (since removed) I recommended using bear canisters for your food.  I was persuaded by @Charlie Brumbaugh that bear canisters as a cougar preventative are overkill: bears are attracted by food lying around, cougars are not.  Cougars are, however, attracted by the small critters (raccoons, mice) that will be attracted by food you leave improperly stored.  The linked source above advises householders in cougar country:

Feed dogs and cats indoors. If you must feed outside, do so in the
  morning or midday, and pick up food and water bowls, as well as
  leftovers and spilled food, well before dark. Pet food and water
  attract small mammals that, in turn, attract cougars

Note that if there are bears, in addition to cougars, where you will be camping, bear canisters are a good idea.  The anecdote in the answer of @bitsmack suggests that you'd be happier in a tent, as does this excerpt from The List:

As with many predators, a cougar may attack if cornered, if a fleeing
  human stimulates their instinct to chase, or if a person "plays dead".
Answer: In 40 years of hiking in the wilderness, I have never seen a cougar/panther. but I have smelled bears close by. Bears are more common and can be more aggressive. Never have any food with you that can attract them. Also spray yourself all over with Deet, it will keep the bugs and animals away. Yes really! Carry Mace spray. Also, consider carrying a loud radio with some recordings of rock and roll. Yes, all these things will make the Bear and other predators go somewhere else, unless they smell FOOD and they are very hungry.
BTW, One other point, not all cougars/Panthers are like. Just like Bears, in different kinds and regions are more aggressive than others. As an additional point when I camp in the wilderness, I actually camp in my truck
Comment: DEET will also keep those pesky humans away...
Answer: You can't.  If you hike in the back country, you will be attacked by cougars in your sleep.  But don't let that stop you.  You should embrace cougar attacks.
When my family camps out, we take turns doing sentry duty at night.  My ten year old loves it: he gets to stay up late, he gets to hold a gun, and best of all, he gets to shoot at cougars!
Best of luck to you, and enjoy your camping trip.
Comment: This is basically what I told my girlfriend. Let's just go enjoy ourselves and realize we'll probably be eaten. She wasn't as keen on that though.
Comment: This may not be a valid answer, but it is a brilliant answer.
Comment: Agreed! Made me laugh :)
Answer: Big cats as a general rule. Like to attack from above. So do not sleep close to steep facings. Sleep Away from cover. Wild cats do not like the smell of humans. They are probably approaching camp for other food than you. Unless very hungry. Do not get up with out shining a light around area first. Most tiger attacks happen to women. Going for water after dark.  Walking trails to springs.  But snake bites are far more common. So they like to ambush over stalk. This is big cats in general.
Comment: This is good advice for tiger country, but the question was specifically about cougars and how to sleep safely in cougar country.  It would be fine as a comment, but does not really answer the question.


What is the difference between a main panel and a sub-panel?

Question: I have a main breaker box that feeds a panel in my basement. This basement panel then feeds a panel in my backyard garage. The panel in the backyard has neutral and ground wires mixed on the 2 bus bars. I have always thought the basement panel and backyard panel were sub panels to the main breaker box. The backyard garage panel does have it's own grounding stake just outside the building. Does this make it then a main panel and not a subpanel even though it is fed from a sub-panel in the basement. Just trying to understand what all constitutes the designation of main panel and sub-panel.
Comment: There's no such thing as a "sub-panel", it's just a term used to describe panels supplied by other panels. There's a bunch of codes that deal with how the grounding and grounded conductors are handled in panels (especially in seperate buildings), so it may not be as cut and dry as you'd think.
Answer: A main panel (or service entrance panel) is simply a panelboard that contains the main service disconnect for a property -- this can be up to six circuit breakers in a rule-of-six (split bus) panel, but is more commonly a single main circuit breaker or fused disconnect (such as a pullout).
Or in other words: the service from the electrical utility enters the main electrical panel for a property, and all other panels on that property are subpanels, as long as there is not a second utility service or a transformer on the property.  There are also other special cases such as multiple section main panels, but they're beyond the scope of this answer.
Answer: There are two answers depending on which version of the NEC was in force when the electrical service install. In many versions the main panel is bonded (ground and neutral tied together. In current versions of the NEC bonding has been moved to the transformer only. In really old versions sub panels may also be bonded (because they did not have a ground connection to the main panel). So the end result is that in modern and ancient systems the only distinction between main panels is that shutting off power to the main panel also shuts off all the panels it feeds, however for most installed systems there is also differences in grounding, specifically one arcane case in which power enters a property at the back of the house, where there is a main panel (bonded, ground rod, no ground from pole) which feeds a sub panel in the basement (not bonded, ground wire from the main panel, may or may not have it't own ground rod) which feeds a detached garage which has it's own main panel (bonded, ground rod, ground not connected to the house). this presents odd challenges in cross building circuits (yard light switched by three-way switches is required to have one and only one ground connected to both buildings ground while not connecting the grounds between buildings, which is why we installed a motion detector instead). Fortunately the new rules no longer allow this.


Would my fridge be causing the 20amp gfci to trip

Question: I recently bought a house and when I went to plug the fridge in it worked fine however the next morning. I wen to check on it and found that the circuit had been popped as well the ice machine was on at during the night. The I turned the ice machine off and reset the breaker and plugged the fridge in and it worked for a while but it eventually tripped the 20 amp gfci this time and as well as the next time. I Will note that the fridge I self not plugged into a gfci but is wired from one could this be causing the problem or would there be other reason for the fridge to be popping the gfci?
Comment: Related: http://diy.stackexchange.com/questions/53252/why-is-gfci-tripping-on-refrigerator-circuit, possibly a duplicate question.
Answer: The fridge is most likely tripping the GFCI. Most folks recommend not plugging refrigerators into GFCI circuits, for this exact reason.
Refrigerator manufacturer's still have trouble controlling current leakage, and most of them are basically ignoring the problem. One day the manufacturer's will be forced to address the problem, but until then they'll likely keep tripping GFCIs.
Either run a non-GFCI circuit to plug the fridge in, or find a manufacturer that doesn't have the problem, and by a fridge from them.
Answer: The compressor motor on the refrigerator (an inductive load) can cause GFCIs to trip even though there's no current leakage.  Although code requires other kitchen receptacles to be GFCI, the refrigerator can be on a regular non-GFCI receptacle.  The best thing is for the fridge to be on non-GFCI circuit by itself so there's nothing else potentially tripping the circuit and causing spoilage.


How does the mass of launchers change over time between ground and orbit?

Question: I would like to see some comparison between different launchers wrt how quickly their mass is reduced over time (or altitude or velocity). There are differences in overall size class, propellant type, number and size of solid fuel boosters, common cores, burn time of the first stage and certainly more. It would be interesting to learn something about how current and historic launchers differ in getting rid of mass over time.
Comment: The answer would simply be the total propellant mass flow...which is why I think potential answer-ers are kind of scratching their heads over this one.  For example STS used, in round numbers 3000 lb/sec in 2nd stage.
Comment: @Andy What really interests me is how different launcher designs philosophies compare in this respect. How soon mass (fuel and ejected stages) produce results in terms altitude and velocity. What launch profiles different design choices lead to. I don't want you to waste your time by plowing through specific Wiki numbers per se.
Comment: @Andy, the reason is that the rocket equation only starts to really bare its teeth if you want larger amounts of Delta-v. For the first stage, hydrogen or kerosene doesn't make such a huge difference.
Comment: Do you mean just a trawl through Wikipedia dividing stage fuel loads by their burn times? (eg Saturn 5, stage 1 is around 2000 tonnes in 160 seconds or so) ?
Comment: What do you mean by "the mass of the launcher"? Do you mean how quickly fuel is expended? How early stages are separated? When the fairing is dumped? The sum of all?
Comment: @Rikki-Tikki-Tavi Ideally, I'd like to know how the remaining mass of the launchers decreases during the few minutes it takes for them to reach orbit. If it varies significantly between types.
Comment: That's a good point about design philosophies. For example the Saturn 5 first stage used RP-1 fuel despite its lower efficiency (lower specific impulse), either to keep down the overall volume or just to get adequate thrust off the pad.  Its upper stages use more efficient hydrogen because they would already be airborne when their turn comes. (I don't have a reference for this right now unfortunately - just something I read somewhere...)
Answer: In almost all cases, the overall mass versus time curve for a multistage launcher will approximate an exponential decay curve; this is the nature of the rocket equation.
Within each stage, if all the stage's engines fire at a continuous throttle setting, the mass decline over that portion of the flight will be linear. Many launchers throttle down over the course of a stage's burn in order to control g-loading, which makes the mass decline more closely approach the exponential decay curve.
Here's one simulation result, for the Saturn V with Apollo payload:

Each stage is generally linear, though there's a slight kink near the end of the first-stage run when the center engine cuts off to limit G-load, and two kinks near the end of the second stage run for center engine cutoff and propellant mix ratio shift. The vertical jumps in the plot are the stage drop events.
Here are some more modern examples: Falcon 9, Delta IV Medium (4,2), Vega, and Proton M. For the F9 and D4, I've simulated abrupt throttle step-downs, so the stage mass curves are kinked. This is accurate for the Delta, but possibly not for the Falcon; if the engine throttles down gradually the stage mass curve would be smooth, but the overall shape would be essentially the same. Vega's first three stages are solids, with poor specific impulse, so its mass curve is quite a bit deeper than the others.

Individual launcher design choices appear to account for more variation in the exact shape of the curve than historical trends.
That said, there is a tendency in modern launchers to use very low-thrust upper stages (Falcon 9 being a bit of an outlier), so their graphs tend a little steeper at the start and shallower at the end. Ariane 5 ES is an exemplar of the trend:

The Atlas LV-3B used for the Mercury orbital flights is the opposite of that trend, with high acceleration throughout and a very short time to orbit; its mass curve is somewhat shallower, but not dramatically so:
Comment: Great answer! Again. You say that the kinks on the curves are caused by throttling down. But what about the mass reduction from ejecting the empty boosters or stages? And even if data is not available, how do those mass/time profiles qualitatively compare with Proton, which (I think) separates its first stage earlier? And with solid only first stages, like ICBMs or India's PSLV.
Comment: Or the Ares I test launch, with a solid fuel first stage.
Comment: The vertical jumps are stage drops; the slighter bends are the throttle-downs. I'll annotate the Saturn V graph since it's got the most going on, and I'll try Proton and a solid-based launcher and see if the graphs are interesting.
Comment: Proton's early first stage separation is due to its 3STO design. It's actually the closest of my examples to an "ideal" exponential decay.
Comment: Vega's an interesting one.


Why do cameras include very high ISO settings even though they are so noisy?

Question: Why do they make DSLRs' ISO settings go so high? I own three different Nikon cameras and every one of them, once you pass a pathetic 320 ISO, the noise in my photos is lousy and — all 3 cameras cost over a thousand pounds each.
Comment: If ISO 320 has too much noise, either your cameras are ancient, or your expectation of noise is simply far too high.
Comment: It could be helpfull if you specified which cameras you are talking about.
Comment: Possible duplicate of [Is high ISO useful for photography?](https://photo.stackexchange.com/questions/12480/is-high-iso-useful-for-photography)
Comment: Could you also provide a sample image at ISO320. To me ISO320 is low and still well within the bounds of shooting fashion in the studio. To be honest I wouldn't expect any noise at 320 unless i pixel peeped. Reading your other post it seems that you're expecting the impossible.
Comment: I had to shoot ISO25600 on Thursday ... was quite pleased with the lack of noise if I'm honest... And yes. Had to.
Comment: @JOHNBOYM I've played with the Nikon D7000 (something older than the D7200), and ISO 320 has minimal noise. ISO 320 would be about fast enough for interior shots with a prime lens, and you might find some noise in the shadows, but nothing too disagreeable.

ISO3200 is very different.

Do you have a sample of the noise that you're talking about?
Comment: ones is the nikon D750 the other is the nikon d7200 and the other is the nikon d650 " I wouldn't call any of them old or cheap...you should never judge a book by its cover Calyth.
Comment: Related: [Is there any point in ultra-high ISO for DSLR [not film]?](https://photo.stackexchange.com/q/84455/15871) and [Can ultra-high ISO ever yield good results?](https://photo.stackexchange.com/q/25795/15871) and [What is the highest acceptable ISO to use for weddings with Canon 7D?](https://photo.stackexchange.com/q/43546/15871)
Answer: The short answer is: because it's useful. I'd much rather have to deal with a bit of noise at 3200 and to still get my shot, rather than not getting my shot at all.
The real question is: what is the maximum amount of noise you can deal with for your intended photo and, given that, can you still get your shot?
ISO 320 is really low for any camera made in the last 5 years (personally, I considered ISO 800 on a 20D the absolute highest I could go - and that was back in 2006.)
I'm wondering if you are underexposing your shots and trying to increase the exposure in post. This will exacerbate the noise. Can you add some more info about your shooting to your question, including a sample shot?
Comment: Looking at OP's other question, I'm starting to wonder if he isn't seriously underexposing to get a sharp image, and then tries to get something visible in post.
Comment: Oh the days of wincing at an ISO we weren't comfortable using and now we're using in the day to day!
Comment: But OP was complaining about noise at 320 ISO (10 times lower...).
Answer: On DSLRs, ISO is essentially done by increasing the gain on the sensor, or if you will, amplifying the signal.  In some respects, this is not unlike turning the volume up on a speaker: nearly all speakers do well enough in 'normal' ranges, but when you turn up the volume, cheaper speakers begin to distort and color the sound. Better speakers simply get louder without distortion. Even better speakers can fill an arena with sound, even when full of people, and still not distort.
This is similar to camera sensors: most do well enough when there is plenty of light and no need to amplify beyond the 'native' ISO of the sensor. But when challenged, such as in low light scenes, they quickly exhibit noise, effectively making them useless.  However, much better (and more expensive) cameras, with better sensors, exhibit little noise in such conditions.
As an example, my earlier Canon 40D was useful to about 1000 ISO, but beyond that the noise was too much to provide really marketable images. It was an expensive camera when purchased new. My much newer Canon 5DMkIII has a much better sensor, and happily yields good images a ISOs far beyond 3200+ (and often as far as 12,000). It is a more expensive camera, but a worthwhile expense in my opinion.
Why do cameras have high ISO settings even though they produce less than useful results at those ISOs? An image is really in the eye of the beholder, and I suppose its the same reason cars have speedometers marked with top speeds beyond the capability of the car or why some guitar amps go to 11.
Comment: Your Canon 40D was noisier at ISO 1000 than at ISO 1250 due to the way Canon cameras do the '+1/3' and '-1/3' stop settings. [Is it really better to shoot at full-stop ISOs?](https://photo.stackexchange.com/q/43756/15871) and [Is analog gain really actually power-of-two only?](https://photo.stackexchange.com/q/64127/15871)
Comment: The car example sucks - first, car manufacturers know tuning exists, second the speedometer is often the same for all car variants with all engines. I.e. YOUR model may not go that fast, but the top model may. Part of keeping the part count down.
Comment: The speaker analogy is not a good one. Noise and distortion are not the same thing. Your speaker analogy, translated to the visual domain, would manifest as blown out contrast, the sorts of effects you can get playing with the levels tool in an image editor. Noise at high ISO settings is mostly thermal noise that was there all along, but which has now been amplified more along with the signal. It's like trying to clarify a weak radio station by turning up the volume: sure the station is louder, and so is the noise.
Comment: Something many people do not consider is that the camera can be used to produce lower noise photos by taking MORE photos and averaging the results. Astrophotographers do this all the time. Most photographs (and photographers), however, are not well suited to this method.
Answer: The first picture, taken by Niepce in 1829 required  a shutter speed of 8 hours. Since then, light sensitive materials have gained incredible sensitivity. Now we can freeze a hummingbird's wing in flight. The photo industry designated The International Standards Organization of Geneva Switzerland (ISO) as the official regulator to devise testing method and assign sensitivity to light values.
Should we desire to image in low light situations or when occasions dictate a super high shutter we up the ISO.  High ISO's come with a price. If we are imaging with film, we get "grain". This is a lack of uniformity called "grain". It is caused by a clumping of the light sensitive silver salts we have piled on to get a speed gain.
Digital cameras image work by swapping light energy for an electronic signal. Because the amount of light playing on the imaging chip is incredibly weak, the resulting charge must be amplified to get a decent picture. The amount amplification applied remains moderate when the ISO is low. When we reset the ISO to a higher value the software strengthens the amplification.  Sorry to report that the iamge signal is intermixed with both a good and a corrupt signal. When the amplification is upped, both the good and the bad signal are boosted. This affords an opportunity for the bad signal to show itself. We call this image degration static or in photo jargon "noise".  Noise is seen as a granularity akin to grain seen in film.
Photo engineers dream about making systems that produce a faithful image. So far no cigar! Imaging chips evolve. Maybe the next generation will be free of "noise". Maybe you can study and take up the quest. Maybe the faithful image is right around the corner.
Comment: Basic physics says that there is no such thing as noise free.  So no, we know for sure that the next generation will NOT be free of noise.
Comment: Alan expertly put and oddly enough I understand your explanation maybe ISO will tend to be may last option to improve light and try and adjust shutter and apature first.
Answer: High ISO settings with lots of noise can be useful in some situations.  The obvious case is where you get a noisy picture instead of no picture.
However, my main point here is that noise can be traded off with resolution.  A high ISO picture at the full 12 Mpix may be quite noisy.  Filter that same picture down to 1 Mpix, and you may not notice it at all.  1 Mpix pictures can be quite useful.  You usually don't even need that if the purpose is to embed the picture in a web page.  Note that 1000 x 1000 is 1 Mpix.  That's bigger than you need for a web page most of the time.
So high ISO can be quite useful when you only need small pictures.  In that case, it gives you better f-stop and shutter speed combinations than you would otherwise not have access to.
Take a look at tests I've done to see the noise at various ISO settings of my camera.  While there is a lot of noise at high ISO in the original picture, the versions filtered down to 700 kpix are all pretty much the same.


How do I make my Tor Browser a relay?

Question: I have the updated version of Tor, but there is no console after the Tor connection is made and the browser comes up. I would like to run a Tor relay but am unable to due to lack of Tor console. Thank you.
Comment: Hey Hugh, I edited your title so it's more attention-grabbing from the questions page. Feel free to tweak with another [edit] if needed.
Comment: +1, good point, I hadn't thought of this with the new release. (I love the new version BTW,) and I'd think this should be simple, however a quick glance through the menus (on a Mac) turned up nothing.
Answer: I suggest running a Tor relay separate from your Tor Browser Bundle's Tor client instance.  This way, you can leave the relay up when you restart your Tor Browser Bundle, and the configurations won't collide.
Some examples:
For Mac OS X, you can use the MacPorts package system to 'sudo port install tor', or use Homebrew to 'brew install tor' or use Homebrew recipes for development versions of Tor.  See also Tor Project: Mac OS X Install Instructions for more Homebrew and configuration ideas. All those will install a system or user Tor binary for the relay to use.
For Debian/Ubuntu, the Tor relay configuration instructions state the following:

Do not use the packages in Ubuntu's universe. If you're on Ubuntu or if you want to track newer Tor packages, follow the Tor on Ubuntu or Debian instructions to use our repository.

On MS Windows, check the Tor Project's package repository for an appropriate relay bundle.
For all of those, you will want to also read up on Configuring a Tor relay.
And most importantly, thank you for running a relay.
Answer: Tor's official instructions on how to run a relay:
https://www.torproject.org/getinvolved/relays.html.en
Comment: Can you please copy the main points here or give a slight overview? A good rule of thumb is that all SE answers should fully answer the question without requiring the user to leave the site or click on links which might be broken in a few years time. Thanks!

How do I make my Tor Browser a relay?


Calculating Fees (Kane, Marcus, and Trippi)

Question: Having read a chapter in Bodie, Kane and Marcus' Investment, I came across a formula I do not quite understand. It states that the percentage fee in excess of what an index fund would charge on active management of an optimal portfolio is given by
$$f = \frac{1}{2A}\sum_{i=1}^{n} \left[\frac{\alpha_{i}}{\sigma(e_{i})}\right]^2.$$
When applying the formula to the following question, I can not seem to get the correct answer:

One mutual fund has a team of analysts that performs security
  analysis. They are able to produce forecasts of annual alphas of 1%,
  on average, in a universe of 100 stocks with an accuracy of 5%
  (measured in terms of r-square). The standard deviation of the
  residuals is 6%. The assets under management of the fund are
  $50,000,000. What is the amount of fees the fund can charge from a
  mean-variant investor with a risk aversion of 3 (in excess of a
  passive index fund)?

A few things I can immediately deduce is the value of $A$. It then becomes quite ambiguous. I am assuming that the $i$'s of the alpha's and standard deviation of residuals correspond to stocks in the active portfolio. However, what am I exactly summing here? I only have one value for alpha, and it seems that it is representative of the whole universe of stocks. Any help would be greatly appreciated. It seems that the answer is "$57,870,37". As you can see, there is a typo in the answer which makes matters worse.
Thank you to all in advanced for you help.
Gus.
EDIT
After a tiring amount of trial and error I have come to a solution I do not understand.
$$f=\frac{1}{2\cdot3}\cdot 100 \cdot \left[\frac{1\%\cdot \frac{5}{10}}{6\%}\right]^{2}.$$
Why multiply the alpha by $\frac{5}{10}$?.
Answer: It is supposed to be multiplied by 5/100 (5%). You should then be able to get $57,870.37 if you multiply it by the fund value.
Comment: Yes, that's correct. Alpha's have to be multiplied by the $R^{2}$. If you could elaborate on your solution (for future viewers) I will gladly give you the tick


Recommended destinations located close to Siem Reap, Cambodia

Question: My wife and I are planning an "adventure" honeymoon to South East Asia in February 2012.  We have our eye currently on Angkor Wat (Siem Reap, Cambodia).  Our honeymoon will be for 2 weeks and we are interested to hear what other places in the surrounding area that are recommended as we know Angkor Wat will not take 2 weeks to see.  We are up for taking a short flight or bus and crossing into other countries.  We like hiking, jungle tours, seeing animals, beaches, and seeing interesting "old" things such as temples and ruins.  We're not fans of big cities and night clubbing/partying.  We are both seasoned travellers.  Any suggestions or small "hidden gems" would be highly appreciated!
Comment: For more discussion of whether recommendation questions belong here please see: http://meta.travel.stackexchange.com/questions/6/are-recommendation-questions-on-topic
Comment: This question could be subjective (different people will like and dislike different destinations) and open (there's not one right answer). Both of these qualities are considered bad for StackExchange questions but I won't downvote or close it until we hear from some others.
Comment: How would you suggest re-writting the question to make it less open?  I had considered something more direct such as "What are some adventure based destinations close to or within Cambodia in February?" but I felt that would yield similar answers.  Perhaps just leaving out some of the more detailed information could make it more concise?
Comment: @justinl: In this situation, the more specific you make your question, the better so that it doesn't sound so open-ended. I think you've done well enough to narrow down the criteria.
Comment: @justinl: It's not *concise* questions that SE looks for but *precise* ones (-:
Answer: Two weeks is a decent amount of time to explore Cambodia. Here are a couple of my recommendations:

Siem Reap: The Angkor Wat and surrounding temples can either be covered in a day, or over a couple of days. This is important because you need to buy a pass, and there are passes of different durations: 1-day ($37), 3-day ($62) etc. There's a 7-day pass ($72) too but unless you're an archaeologist or a serious history nut, you won't need it. Hunt around for a tuk-tuk driver in the city who can speak English well; don't expect that if you book through your hostel/hotel they will be good. The tuk-tuk driver I hired on the first day, although a nice guy, didn't speak any English at all and it got incredibly frustrating when I want to deviate from his 'standard' route a bit to check out some of the other temples I was interested in. So go to the Central Market, look around for drivers, and negotiate. The standard rate you pay to them is $13-15 for the day. You can either pay a guide - which is great for some of the smaller temples, as the security guards can show you around to earn a bit on the side. At the bigger temples, there are official tour guides appointed. Personally though, I just bought one of the guidebooks they hawk at the temples - it's called Ancient Angkor, if I remember, and should cost you $6-8 (you'll have to bargain). This will really help you understand some of the history behind the temples as the book has in-depth information on even the smallest of temples. Do note however that currently many of the temples are going restoration work (and have been, for a while) so you may not be able to visit all sections of the temples. One thing you should definitely try out though is SkyVenture - which is run jointly by a British pilot and an American archaeologist who has been living there for around 9 years, and used a microlight to do ground radar scans to study the area. They take one person at a time to a tour of all the major temples from the air, and as an archaeologist he tells you information about the temples - things discovered from those latest ground radar scans - that you won't even find in many books. They don't allow small digicams, only SLRs on their flights so if you want to take pictures get one of those. Best go at sunset because the temples look really beautiful then!
Battambang: This isn't far from Siem Reap, and the more 'scenic' journey is to go there by boat. However, when I was in Cambodia this was not in operation because of something about water levels. You can either hire a tuk-tuk or take a bus. I found the bamboo rail system they have there very unique, very worth it.
Sihanoukville: I'm not sure whether you'd like this or not. The beaches are nice, however, it is sort-of touristy and party-atmosphere like. Much less than the insanity of Thailand though, and there are a couple of places that are more relaxed.
Banlung and Kratie: I haven't been to these two places but there are good hiking trails near both these towns. I'm sorry I can't give more information about these two but I think you'll like them.

I'm not sure which airport you're flying in to - probably Phnom Penh? There isn't much of 'undiscovered' stuff to do in PP, and it's a fairly bustling city by Cambodian standards. The problem mostly is that the places I mentioned above often don't have direct bus connections that you can take, and everything interchanges at PP (the major bus operator is PP Sorya Transport). So you might find yourself having to go back, although most bus journeys are no longer than 6-10 hours long.
One bit that I really want to do was cross overland into Laos from Cambodia and travel further up to Vientiane. Actually, I was more interested in the Si Phan Don ('Four Thousand Islands', although I don't think there are precisely that many in reality :D ) which I've heard is a very laid back and beautiful place to relax in. I couldn't seem to any bus operators for that bit though (very surprised by that! I was told I need to go back to PP and catch a bus from there instead) but for two weeks, it's a less touristy place and you might like it. Also, apparently, they had stopped issuing visas on arrival at the land border; if so, you'll need to get a visa in advance, which you can at Phnom Penh.
Comment: Oh, and don't think the 'organised' bus company are very touristy - you'll only find a handful of *farangs* and mostly locals on the buses. Families, farmers, traders... And they play Camdodian (Laotian?) music videos, and Bollywood song-and-dance routines from the 60s-80s!
Comment: Thanks Ankur for the very detailed answer.  This is really helpful and very much appreciated!
Comment: @AnkurBanerjee - that is so true about the music videos on the coaches. I found it to be almost torture on a 5 hour journey
Comment: great answer, +1 for the skyventure tip (very tempting)
Answer: While in Seam Reap I'd also recommend going on a boat trip on the Tonlé Sap lake to see the floating villages. As Ankur suggests you can hire a tuk-tuk driver for the day for like $15. We hired one who drove us to the lake (which was an adventure in itself down a crazy mud/clay road) and came with us on the boat trip. It lasted a few hours and was quite cheap (can't remember exactly maybe $5-10 each). Whilst on the trip, young children come aboard pirate style offering to let you hold their pet snakes for $1 - very surreal but awesome! On the edge of the lake there is also a large hill called Phnom Krom. There is a temple at the top, but the main attraction is the spectacular view of the lake.
Below are some pics.


What must I put into my portfolio to make it an INTERACTIVE DESIGN portfolio?

Question: If I were to apply for Interactive Design positions, I would certainly include a portfolio. However, coming from a background of Web Design, I don't necessarily have the best ideas on how to distinguish myself as an interactive designer. What must I put into my portfolio, or how must I organize it, in order to make it clear that I know how to be an Interactive Designer?
Answer: Might just be me but if I was hiring I'd be interested in seeing how you got to your solutions, not just the solutions themselves. I'd want to see how you think, why you did certain things and a broad base of materials that illustrate your skills across IxD -- be it wireframes, personas, mental models, sketching, facilitation, etc.
Anyone can learn tools (e.g. OmniGraffle, Visio, InDesign, etc.) but you can stand out by showing how you apply your skills to solving problems.
I'd suggest giving Whitney Hess' article a read, I think it address well what people are looking for in IxD portfolios:
http://www.uxmatters.com/mt/archives/2009/10/process-not-portfolio.php
Comment: benry... I truly appreciate your answer, because it got me to think about what I really want people to see... I'm sure employers get bored by just "viewing portfolios". The article by Whitney Hess was eye-opening. Thank you!
Answer: Show off your enthusiasm for this type of work. List groups and communities you participate in, posts you've written, links to proof-of-concepts you've done on your own, scan in "your napkins" and put them up if they show off your thought processes, link to answers you've supplied on listServes,.. and so forth.
Answer: In addition to Benry's answer, you could perform some usability testing to demonstrate understanding of evaluation as well as design - perhaps a heuristic evaluation either of your own work (different versions, showing improved IxD) or an existing interaction that you love/hate.
Ultimately your portfolio is going to influence your potential employers by showing them your skills, approach, personal style, software adept with etc.  Having a good range of design and evaluation pieces in your folio should help to suitably impress.
Answer: Benry put it nicely.  Assuming your site has more than one page, then it had navigation.  Navigation is an interactive element.  Is there a form on the page?  Any JS you used?  People interact with websites.  Think from that perspective.
I spent a year at Intuit just helping them with static websites.  My title was interaction designer.

There is only one place you have not looked.  And it is there...only there, that you will find the master.  - The Last Dragon


Changing screen resolution with with Windows 7

Question: I'm using a Dell Inspiron desktop computer hooked up to an old Venturer monitor. When I go to change the screen resolution under Personalization, Windows won't allow me to make any change from 1024 x 768, which won't work (the right side of the screen is missing). It doesn't even seem to detect the monitor. Can I manually make a change to resolve this situation?
Answer: It seems you are having a driver problem with your graphics card, not with your monitor. Try to get a driver from the official site of the manufacturer of your graphics card and install it, then see if it is OK.
Another thing you can try, is to see if the settings of the monitor itself are messed up. Try to reset the settings of the monitor by using buttons on the monitor itself.
Answer: Un-hide resolutions, and try again: