If a cube or micro satellite could collect 1-2 cm space debris in Earth orbit could they be deorbited while raising the sats orbit?

Question: A lot of space debris on LEO are small 1 to 2 cm pieces.  Removing these threats is a concern to anyone using LEO.  Can a cube/micro satellite use collected small debris and propel them to both deorbit the debris and gain orbital velocity itself?  A small rail gun perhaps.
Comment: The collector has to spend propellant to match orbits with the debris to collect it.
Comment: Teoretically it would probably work with some kind of ion truster that is not picky with which elements it ejects. Practically I have a hard time seeing this in a very long time.
Comment: This isn't a good SE question. Answer like "Yes" and "No" can equally be defended depending on a variety of unconstrained assumptions you're leaving wide open (cost, how soon, dependencies on other technologies, etc.). This means that the answers are more-or-less primarily opinion based. Can you adjust the question and ask something that has a clearer answer that's going to be somewhat factually correct? For example, you can ask what are the most challenging issues or likely show-stoppers.
Comment: Surprisingly little of the LEO space debris is in the 1-2 cm range.  Maybe only 0.1% of the damaging flux.  (see http://hdl.handle.net/2060/20150003036).  Removing these will make very little difference in the general risk to LEO spacecraft.
Answer: In theory, yes. But in reality, no - not yet, and probably not ever.
If you could build an ideal collector, something to sweep debris into an inlet where it could then be accelerated to raise the satellite's orbit, then this could work. But in reality, to try and catch debris with a different vector to the satellite's (and possibly dramatically different velocity) would require manoeuvres, and these would consume a large amount of propellant, and probably require a very large collector, whether it be a net, a magnetic funnel of some kind...which also requires more impulse to move etc.
There are numerous concepts to try to de-orbit debris, ranging from lasers to magnets to mirrors and various others.


What prompted all of those private launch companies to get into the business?

Question: It seems that, somewhere around the turn of the century, a bunch of private companies started gearing up for launching things into space when nobody (at least not private entrepreneurs) seemed very interested before that. Did some specific thing happen that made it possible or made it attractive?
Comment: Oh, "the turn of the century" is 2001, I keep thinking of the one in 1901.
Comment: Wasn't the [X-prize](https://en.wikipedia.org/wiki/Ansari_X_Prize) a major turning point?
Comment: This is a perfectly reasonable question seeking facts, and already has one *fact based answer* posted, no need to close for "primarily opinion based".
Comment: related: [Why is private spaceflight suddenly expanding so quickly?](https://space.stackexchange.com/q/8051/12102)
Comment: @uhoh is correct.  2001 was "the millenium".
Comment: @DrSheldon I mean I'd forgotten that the century has turned again recently.
Comment: On the X Prize: It did spark development. The winner was SpaceShipOne, which was launched from an air carrier. Designed by Rutan of Scaled Composites, funded by Paul Allen. Allen developed the Stratolaunch based on the concept. Branson bought the technology for Virgin Galactic and scaled it up as SpaceShipTwo. Other ventures competed, but I don't have my notes on hand. Julian Guthrie's book How to Build A Spaceship describes it.
Answer: The internet happened. Specifically, young engineers (Elon Musk and Jeff Bezos) made gigantic piles of money (more than they could ever use in their original companies), and with that money they decided to follow their interests.
I.e. they had lots of money to pour into the business, and no requirement to make money within a set amount of time. This is incredibly rare: almost all investment comes with strings attached. Rocket development is a high-risk business and was not seen as attractive to investors (which is why many earlier commercial rocket ventures failed).
Comment: Internet millions made it work, but lots of commercial space companies tried, and failed, before -- rotak, otrak, reaction engines
Comment: While internet billionaires facilitated the creation of these space companies and development of their space technologies, the Ansari X Prize got a lot of people thinking about private efforts to go to space. I would speculate that it was very likely the X Prize that steered the thinking of folks like Musk and Bezos toward space ventures.
Answer: Just to supplement @Hobbes' correct answer:

The internet happened. Specifically, young engineers (Elon Musk and Jeff Bezos) made gigantic piles of money (more than they could ever use in their original companies), and with that money they decided to follow their interests.

Other zillionaires, seeing those two's successes, piled on as well (Richard Branson, Paul Allen, etc).
In fact, Paul Allen might belong in the list of internet engineer zillionaires. Another indicator of how driven some of these efforts are by the singular dreams of the engineer/zillionaire might be this recent u-turn: Stratolaunch is scaling back operations following the death of co-founder Paul Allen

Afterthoughts, aftertheories and opinions beyond the facts above and in @Hobbes' answer:

I really do think Hobbes nailed it; that it's the relatively "sudden self-made money" in the hands of individuals who learned that they can move mountains, liked it, and then looked for the next one to move.

It's been a half-century since spaceflight became an inspiration, those who watched the moon landings as kids had made their zillions and the seeds of inspiration planted a half-century ago could sprout.

Rockets are finicky and are wont to blow up, so developments in †cylindrical rocket launch technology have been a bit slow and institutional, leaving the field of spaceflight ripe for new innovators who simply needed to borrow some books on the topic, devour them, and according to space lore not return them.
†as opposed to shuttle launch technology, which was institutional but not slow
Comment: The link that you provided up above does a lot to answer the question. I was looking for an event that fired the starting gun, like relaxing a legal restriction or something. But it looks more like an evolutionary explanation--launch business increasing, new technology bringing down costs, and some internet geeks with money showing 'em how it's done.
Comment: @uhoh: It's not a common word, and unless you read archaic books for fun you're unlikely to see it much!
Comment: @Greg your comment causes me to ponder further. That along with my morning coffee temporarily providing a rare condition of not one, not two, but three neurons firing at the same time, has lead me to add a few more points.
Comment: @NathanTuggy thanks for the corrections, didn't realize it was "wont" (blush).
Answer: I admit, I wasn't comfortable with the "internet geeks" part of the answer. So I've been doing some reading. And, sigh, I suppose there's something to it.
I was wrong to suppose that someone fired a starting gun around the turn of the century. Interest in private space activities goes back a long ways. For instance, International MicroSpace, founded in 1989 by Peter Diamandis, to take small payloads to low-Earth orbit. They eventually got a $100 million contract from the Department of Defense, but no money up front, so they were unable to develop the technology, and the company, with contract, were sold to CTA in 1993.
Recurring themes are development being more challenging than expected, costs running higher than expected, and difficulty in finding investors. It's the life cycle of companies like Armadillo, Rotary, and XCOR.
The companies with staying power are the passions of billionaires who can afford to lose money on hobby businesses. Elon Musk, Jeff Bezos, the late Paul Allen, and Richard Branson. Branson isn't an internet geek, but he has, like, a hundred other companies that are keeping a roof over his head.
I'm not sure what's going on with others, like Boeing. I don't know if they're going independent or still doing NASA contract stuff. Orbital Sciences merged with Alliant. Exos is still operating (and it looks suspiciously like Armadillo shed its creditors, changed its name, and just kept on working...) There is a lot more going on than I can catch up with in a short time.
Edit (I'm still picking away at this, there's a lot to sort out.)
In 2010 Obama killed the Bush-era Constellation program, calling it "over budget, behind schedule, and lacking in innovation", and reoriented NASA toward the private sector. In 2015 he signed the Commercial Space Launch Competitiveness Act of 2015, which gives private US companies the rights to resources they mine in space. (Also Davenport, 160, 249)
The space economy has grown from \$175 billion in 2005 to almost \$385 billion in 2017, a 7% per year increase. The Space Economy: An Industry Takes Off. That has been fueled in part by new technology shrinking the size and cost of satellites.
Investors had typically shied away from space, and quite a few companies ran out of cash and shut down as they ran over budget and couldn't convince investors to continue backing them. And the way that NASA, in previous decades, discouraged competition went something like: American Rocket Company spends years developing a hybrid engine only to have NASA fund a competitor to duplicate its work (Guthrie, 130). In other words, the company goes under because the private sector doesn't support it and it doesn't get the government money. Now NASA is spreading some sugar around to support the private industry, and private investors are wading in, pursuing an expanded market. And Elon Musk, and SpaceX, has a lot to do with making the private industry credible with technology development, and also prompting lawmakers with its lawsuit challenging the Air Force on anti-competitive contracting.
Space is hard. And expensive. More so than some people seem to think, even if they say they know that. But new technology is bringing down the costs of everything and simultaneously expanding the market, and there have been changes in some laws and political attitudes that are now specifically trying to encourage and to rely on the private sector. SpaceX has to be given a lot of credit for shifting the public and political attitude. That's about my best summary answer to the question so far.
Davenport, Christian. (2018). The Space Barons: Elon Musk, Jeff Bezos, and the quest to colonize the cosmos. New York:Hachette.
Guthrie, Julian. (2016). How to Make a Spaceship. Penguin.
Comment: Commercial Space Act of 1998 was designed "to encourage the development of a commercial space industry"
Answer: Further, the Commercial Space Act arose due to NASA's bad behavior during the Shuttle era discouraging competition from other players - including their own contractors. Totally-private players like Pacific American Launch Systems found themselves in a funding bind that went something like this:

LauncherCo: "Dear Angel Investor, we have this concept for a cheap reusable launcher..."
Angel: "Hmm, interesting. We'll do some due diligence and get back to you."

The angel investor, not knowing rockets from rocks, tries to find an 'expert' to vet the proposal, and calls NASA, or one of their contractors with incentives to not upset the gravy train...

NASA: "We've never done that." [insert other phrases creating Fear, Uncertainty, and Doubt]
Angel: "Sorry, LauncherCo, I can't take the risk."


GFCI outlet trips from any heating element

Question: I have two GFCI outlets in my kitchen one each side of the sink.  Each outlet then has three outlets after it which when the GFCI trips interrupt their connection as well. I feel this is pretty normal but I did not wire it. No work has been done in this room in quite awhile like years. Just this past week my vacuum sealer started tripping the GFCI when it's pluged into any outlet down stream. It trips when the heating element turns on. Then last night my instapot tripped it. The instapot has read off that outlet for the two years we have had it. In that same series of outlets we have our toaster oven plugged in and it has never tripped it. I am baffled at what the issue could be. Is it possible that the gfci has an issue and needs replaced or do I have some kind of bigger issue and how do I test to see what my issue is.
Comment: A quick Google search indicates that the expected lifespan of a GFCI outlet is 15-20 years, but that they can start failing in as little as 5 years. Weather seems to be the primary killer so outdoor ones fail sooner. Since these are either side of the sink, they may be seeing higher humidity and failing a little sooner than "expected". It may be time to replace one or both of them, but I'd let the electricians weigh in before doing any actual work. If it was my house, I'd fork over the cash and swap them out to see if that fixed the issue, though. (Personally, I'd do it myself, not hire).
Comment: I have already bought a new gfci but thought I would get input first to see if maybe there is something I am over looking.
Answer: If your vacuum sealer is like mine a plastic case with a 2 prong cord there is not a way for a ground fault , I would say that since you have 2 devices causing tripping and this has worked in the past. the GFCI is failing. I started using weather resistant GFCI outlets in bathrooms quite a few years ago because bathrooms can have very high humidity levels and the outlets being in walls can sometimes condense moisture similar to being outside. I don't normally use WR GFCI'S in kitchens because they are normally larger rooms and not exposed to such high levels of moisture. I would swap out the GFCI. The new ones have more sensitive electronics and constantly self test where older ones I have found failed (test won't trip on outlet or plug in tester) or trip for no good reason like a double insulated device with a 2 prong cord, so this should solve your problem.
Answer: A GFCI trips because of a third path
As you know, electric current travels in loops.  That's why the two pins on your plugs, it provides the two paths intended for use.
Sometimes current leaks.  If it does, it can follow a third path accidentally, and that is always some kind of bad.  Worst being when the third path is through a human or pet.
One big reason for grounding is to be a sacrificial "third path".  Better the ground wire get zapped than you!  Another approach is the GFCI: since current flows in loops, the current on the two intended paths should be equal.  If not, a third path has come into play.  GFCIs compares flow on the two paths, and trips if unequal.
So..... For ordinary troubleshooting of a GFCI trip, look for that third path. Is the appliance sitting in a puddle of water (because your sink does that)? Third path.  Does it trip when you touch the appliance? Third path.  Does the appliance have a 3-prong plug? Third path.
Test the appliance
So our first diagnostic method is to forcibly remove that third path. Mop up the water, stop touching it, set it on a dry plastic cutting board, and if it has a 3-prong plug, get a cheater plug to defeat the ground. (Doing so will make the appliance dangerous.  This is strictly as a test). If that clears the ground fault, the appliance is defective.  Clean it thoroughly, let it dry out, and if that doesn't clear the fault, off to the repair shop it goes.
Other than testing, never run an appliance on a cheater cord with ground defeated.  And if you must, make sure it is a GFCI protected outlet.  (I.e. GFCI upstream of it).
Another test is to plug it into a different GFCI in kitchen or bathroom. If it still trips another GFCI, it's the appliance.
A Neutral-Ground fault
If one GFCI trips every appliance, either it is defective or there is a ground fault in the fixed wiring of the building.  One classic wiring problem is a neutral-ground fault, because this fault alone will not flow any current.  But when a load is placed on the circuit, the fault will flow some return current and cause a trip.
This neutral-ground fault could also be in any 3-prong appliance which is still plugged into the circuit.  Some people go crazy trying to troubleshoot a GFCI problem and it never occurs to them to unplug a certain appliance "because that's always plugged in". This often proves to be the culprit.
If the GFCI trips some appliances and they test successfully on other GFCIs, then most likely this is the above-mentioned neutral problem, except the leakage is small enough that it only trips on high power appliances, such as those that make heat.


What instrument makes the lowest note?

Question: I have heard that the classical Indian musical instrument, the Surbahar, makes the lowest audible note of any musical instrument. I am curious what instrument makes the lowest audible note and what that note is in relation to the lowest note on an 88-key piano.
Comment: The site darbar.org claims the Surbahar can produce frequencies below 20Hz. Looking at the photos of the instrument, I find that very hard to believe. The basic pitch of the instrument is about a fifth below that of the Sitar
Answer: The lower limit of human hearing is roughly 20Hz.
There are a few instruments that can play even lower notes than that, but you'll almost always hear something because you are hearing the overtones.
The lowest note on a standard grand piano is A 27.5 Hz
Some grand pianos have nine extra keys down to a low C 16.4 Hz (this is below the human hearing range, you only hear the note because you hear the overtones)
There are some large pipe organs that can produce a C one octave below that (non-audible 8.2 Hz. Notes that low are felt rather than heard)
Update: There are two pipe organs in existence with a true acoustic 64 foot stop that can produce that 8.2 Hz lowest C: one in Atlantic City, USA and one in Sydney, Australia
Comment: I think I might once have seen a Steinway with those extra keys. There are a couple of organs with a 64 foot stop listed here https://en.wikipedia.org/wiki/Organ_stop. You can theoretically get a string to vibrate as slowly as you want, if you make it long and heavy enough
Comment: I know a Bösendorfer piano has those extra keys. Are there others?

I couldn't find a specific pipe organ that goes that low, but I did find a reference that in order to produce an 8.2 Hz note the organ pipe would have to be 64 feet long. Is there any such organ in existence?

This page https://www.darbar.org/wonders/Surbahar/9 indicates the surbahar is "capable of emitting frequencies of lower than 20 Hz" but it doesn't say how low. Could a string really produce a note lower than a 50-foot organ pipe???

What instrument makes the lowest note?


Is there any non-rocket spacelaunch concept within reach of current material science and technology?

Question: Suppose for a moment that cost would be no issue (and noone brought pruning shears) - could we build any of the non-rocket spacelaunch systems from earth listed here or elsewhere? Which one is the least unfeasable given current technology?
Comment: The list includes spaceplanes, which have - in various forms - been demonstrated or are being developed.  The X-15 and SpaceShipOne were both rocket-powered "planes" dropped from carrier aircraft and both achieved "space" by different definitions (USAF and Karman line), Stratolaunch is currently working on a huge carrier aircraft to air-drop a more conventional looking rocket, the Skylon has both SABRE engines and rocket engines, and various U.S. government projects (National Aerospace Plane, etc) have developed some of the tech. It seems the most attainable.
Comment: https://en.wikipedia.org/wiki/Non-rocket_spacelaunch - My favorite wiki page related to this (judging by the age of the question, perhaps influenced by this :P)
Answer: A light gas gun firing a G-force hardened booster seems like the best bet for lofting some sorts of payloads. John Hunter gave a presentation on the state of the art for this technology at this summer's Icarus Interstellar Starship Congress in Dallas:

Hunter's concept called for launching projectiles that fired a rocket near the apex of the ballistic trajectory to achieve insertion into LEO. His payload was fuel, to be collected in orbit and stored in orbital "filling stations." He formed a company to develop this commercially, Quicklaunch (now called TekLaunch), but was apparently forced out by his partners.
See also Wikis for John Hunter (scientist), SHARP (Hunter's research project at LLNL), and Quicklaunch.
Comment: John Hunter has other talks up online from years ago.  The Quicklaunch site went down and a lot of people took that to mean the project was over.  The talk you posted appears to be very recent, so that's interesting new information to me.  Seems that the light gas gun team is still advocating for it.
Comment: There's a new stub at http://www.teklaunch.com. My guess is that the lack of a web presence for the company relates in some way to the circumstances (unknown to me) by which Hunter was terminated.
Answer: Nuclear pulse propulsion, aka Orion.  There's little doubt it would work.  The limits are not technological, but the fact that boosting an Orion means you're detonating a lot of atomic bombs in the atmosphere.
If you'll accept launches from other bodies the mass driver is the best answer.  You can make the track as long as you like.  Many years ago on TV I saw one that could boost a projectile to 100mph in six feet.  If my understanding of the math is right that means you could easily scale it up to lunar escape velocity with a 3.2 mile track.  Punching through the atmosphere is quite another matter, while a track a few hundred miles long could safely boost an astronaut to Earth escape velocity he wouldn't survive the passage through the atmosphere and the capsule would fall back due to drag anyway.
Comment: why is orion non rocket? The driving force is not chemical, but apart from that I see ne principal difference.
Comment: you're right, but it's weird that it is.
Comment: @mart Section 5.4 on the list the question pointed to is Orion.
Comment: I disagree with your claim. Orion was terminated before the pusher plate could be tested. It was never established if anything could be built to withstand the repeated plasma blasts. Even if spallation (shock waves blasting material off the forward side of the plate) could be avoided, erosion on the wear surface was never quantified. To my knowledge it has never been computer modeled in detail. Even George Dyson's book quotes an engineer saying that he expects that it would disintegrate.
Answer: A rotovator rotating skyhook is within our technological ability - kevlar tether would be able to sustain it.
There are some important problems with the concept, of course. Besides the point that it would be very expensive to build (good 200-400km of kevlar tether shaped so that it can sustain itself against several g and keep tons of payload), expensive to maintain (subject to significant atmospheric drag, needs constant propulsion - although fuel delivery is no longer prohibitively expensive); the whole idea is nutty - the end of the tether dips into the atmosphere nearly vertically as the rotovator "rolls" over the upper atmosphere, and a perfectly synchronized airplane lands, or hooks a payload to it, right in the nick of time before the tip yanks it up and out of the atmosphere, then releases into an eccentric orbital trajectory. So the logistics of the operation are devilishly tricky - imagine a supersonic cargo aircraft, landing on an aircraft carrier which is a submarine that surfaces only for a minute or so.
Comment: I think you sell the system short by emphasizing the payload handoff challenge. Yes, it's like having a bungee jumper pluck a piece of gum off of an X-15 at altitude. That said, we haven't really turned the engineers loose on the problem. We could probably work out a harpoon/winch system where the payload fires a grapple and hooks the skyhook at a range of several hundred yards, or the carrier craft pitches the payload into a ballistic trajectory just before the skyhook snags it with a lanyard or grapple. It sounds roughly as impossible as a Kinetic Kill Vehicle, which are now at TRL9.
Comment: @Kengineer: In IIWW there was a spy recovery system, for recovery of material and even humans (although I'm not sure if any human was recovered successfully). A low-flying airplane has a pair of long, springy metal bars extending diagonally downwards, V-shape, with a wire drawn between the ends horizontally. A balloon with a small anchor is released by a spy, on a rope, with payload on the other end of the rope (on the ground). The plane must just hit the rope of the balloon with the horizontal wire. The rope slides along the wire until the anchor catches it, snagging the rope with payload.
Comment: This could be adapted here. A wide fork with ends connected by a rope extending from the rotovator, payload on a long rope behind the airplane. The pilot just needs to fly through the "fork" and let it snag the rope. The actual difficulty of the endeavor is putting several hundred thousand tons of kevlar in LEO.
Answer: The Wikipedia article you cited spells out your answer in the far right column of the comparison table. Technology Readiness Levels range from 2 to 9. Rockets (proven technology) score a 9. Gas guns and HARP canons have demonstrated amazing muzzle velocities and projectile altitudes in real hardware, so they rank 6. Almost everything else has a good theoretical background, small proof-of-concept models, and few obvious deal-breakers, but would require significant additional development, so they mostly score 2s.
There is a chicken-and-egg nature to your question. If you are going to invest large sums in a launch system, you need to know what you intend to launch. Small packets of acceleration-insensitive materials like fuel? Gas gun or space canon would be great and are already at TRL6. Satellite constellations or space construction project sub-components? Now you need payloads in the 1 ton - 20 ton range and limited accelerations. I'm a big fan of Sky Tram and electromagnetic launch for that type of payload. I'm pretty sure we could adapt a lot of payloads to survive ~30g launch acceleration, which opens the door to an Electromagnetic launch system that's on the order of 130 km long. If you want to transport people in large quantities or payloads which can't be designed for high-gee acceleration, then you need to look toward spaceplanes and spaceplane/skyhook hybrid systems, which (in general) move larger payloads gently and infrequently.IMHO, given a few tens of billions of dollars most of the TRL2 systems in the table could be brought to TRL9. What is less certain is the reliability, durability, and ACTUAL $/kg these systems would achieve, and what specific goal they would support.
Answer: If we build small (few kilometers) Hyperloop-like booster in orbit, and use 'small' ground piece of Hyperloop to put aircraft into orbit altitude (200-300 kilometers), orbital part of the Hyperloop will catch aircraft and increase its speed to 7-8 kilometers per second. This concept is explained here – http://www.launchplatform.space


How does one exert greater force on the ground by jumping?

Question: When one jumps, how does he/she manage to exert greater force on their ground than their weight?
Also, what is normal force and the reaction force (are they the same thing?) and by newton's third law, shouldn't the reaction(weight) when we are standing on the ground that the ground exerts on us send us flying above the ground- why doesn't the law apply here?
Finally, when we drop a hard stone on the ground why doesn't it bounce? Plus, why is the force exerted by the stone on the ground greater than its weight?
Comment: Partially answered by http://physics.stackexchange.com/q/34468/
Answer: There's still something missing from all the answers so far. When you drop something on the ground, say, a rock of mass $m$, by the time it makes contact with the ground it's traveling at a velocity $v$ and thus has momentum $p = mv$. To be stopped completely, its momentum has to equal $0$ at the end. So you have a total change in momentum of $\Delta p$. According to (the most literal, I think) Newton's 2nd law, you have $\Delta p = F \Delta t$, where $F$ is the force slowing down the object over the timespan $\Delta t$ (in reality time is continuous and $F$ is probably changing continuously, but this is enough to illustrate the point).
So, if the $m = 1\ kg$ rock goes from falling at $v = 10\ m/s$ to $0$ in a millisecond or so, you might have $F = \Delta p/\Delta t = 10\ kg\ m/s /(.001s)=10000\ N$, which is obviously much bigger than just the gravitational force of $F_g \approx 1\ kg \times 10\ m/s^2 = 10\ N$.
Comment: Actually I put it in, but your description is better. I edited mine a bit to better it
Answer: In a standing state, your legs exert a force on the ground that correlates to your weight.  Any motion or acceleration caused by the movement of your legs is added to this.
Think of jumping as generating upward momentum in your body.  Your legs are causing you to accelerate upwards and gravity is causing you to accelerate downward.  If you legs don't generate more acceleration than gravity, you will never leave the ground.  Otherwise, your body builds up momentum until the acceleration caused by you legs stops.  At this point, you leave the ground and travel upwards until gravity has reduced you upward momentum to 0.  Then you start to fall.
Don't forget that momentum is stored energy and must be accounted for.
Sometimes a stone will bounce.  This has to do with elasticity.
Comment: I would not describe momentum as stored energy, but rather as inertia in motion. A battery stores energy but has no momentum.
Comment: Newton's Second Law can be rewritten:
force = rate of change of momentum.

http://galileoandeinstein.physics.virginia.edu/lectures/momentum.html
Comment: Yes, but force still is not energy. Force changes momentum, work changes energy.
Answer: When you jump, your muscles are using their chemical energy to contract or extend appropriately to create an additional force on the ground; by Newton's third law, the ground exerts additional force on you, overcoming your weight and pushing you off the ground.
In this case, the normal force is indeed the reaction force, as it is equal and opposite to (the perpendicular component of) the force you exert on the ground. There is indeed a normal force even when you don't jump, but this is balanced by the force of gravity pulling you towards the Earth. When you jump, these forces are still present, but the force of your jump increases the normal force such that it is greater than your weight (the force of gravity) and there is a net upward force, resulting in a jump.
The reason any object bounces is because it deforms very slightly when it hits the ground, but its natural elasticity sort of "pops out" the deformation (think of a basketball), pushing on the ground in a similar manner to a jump. Stones, however, are terribly rigid and inelastic, so by the time the ground applies enough force to deform it, it tends to simply chip or shatter rather than deform elastically.
I don't know why you say the force of the rock on the ground is greater than its weight, so I'm not sure how to answer that bit.
Answer: A net force is required on a object to give it an acceleration. In this case the net force on the body is given by $F_{net} = F_{grav} -  F_{normal} $
To jump up, the normal force has to be greater than the force of gravity. As the normal forces forms a reason pair with the force the body exerts on the ground (usually called weight) increasing the force of your body on the ground by stretching your legs, increases the normal force.
The same applies to the falling rock. Because of the momentum of the rock has to be changed, the force of the rock on the ground is bigger than the force of gravity, therefore the normal force on the rock is also bigger than the force of gravity, generating a net force on the rock which opposes the direction the rock is traveling in. So the velocity of the rock decreases.
Jumping of the rock does not depend solely on the rock. If the ground has some elasticity, kinetic energy is transferred back to the rock causing it to jump. You can observe this by letting a rock fall on a trampoline.
Answer: I think one reason it seems odd (at least for me) that we can jump, swim or walk for that matter, is because  organic or inorganic motorized systems have the ability to make their center of mass move without the cause being an external force. I insist on the term "cause" here because the force from the legs extending is first transmitted to the ground (that is the cause) that then pushes up in return (that is external force).
The point is then that if we imagine our own body as a dead body (like a rock), there is no way we can understand how we jump in the first place; after all a rock doesn't jump!
Also, saying that there is a "reaction" from the ground doesn't solve the problem but merely avoids it and gives too much credit to the ground in my opinion.
I think the simplest way is to model it as "relativistic" collision which is just a simplification of (for people who haven't done QFT yet) or a refinement of (for those who have) Newton's 3rd law.
Let us describe the state before the jump in the frame of reference of the center of mass of the jumper and the Earth:

The jumper has a mass $M_j$ and a momentum $p_j = 0$
The Earth has a mass $M_E$ and a momentum $p_E = 0$
The total momentum of the system is $0$ (because of the frame of reference) and the total energy is $(M_j+M_E)c^2$

For simplicity, let us now describe the state of the system after the jump once the jumper has reached the maximal distance and is about to fall bac on Earth:

The jumper has a mass $M'_j$ and a momentum $p'_j = 0$
The Earth has a mass $M'_E$ and a momentum $p'_E = 0$
Taking as a reference potential the initial condition, we need to consider the distance $d$ separating the jumper from the Earth
The total momentum of the system is still $0$ and the total energy is now $(M'_j+M'_E)c^2 + M'_jgd$

As far as I am concerned, nothing much has happened to the Earth and therefore $M'_E = M_E$.
Applying conservation of energy we thus find that:
$M_j-M'_j = M'_jgd/c^2$
Hence the only way to jump is to loose mass! But obviously here the explanation is not that because you lost mass the gravitational pull is smaller and hence you jump, the change in mass is probably of the order of the mass of cell in your body and plus the potential energy minimum is always the ground regardless of your mass.
No, the explanation lies in the energy interpretation of mass. If I consider an 80 kg person, rounding the gravitational pull to $10\:m.s^{-2}$ and $d=1m$, we get that the mass-energy difference is $800$ Joules.
Again, it has been provided by a mass loss that originates in fact from exothermic bio-chemical reactions (mostly coming from ATP I presume) used to make molecular motors, responsible for muscle contraction, work. A rough estimate from the data I could gather would be to say that for this jump, about 0.1 moles of ATP have been used to process it. Trying to go further is a bit delicate but that could correspond to making 50% of the ATP in your legs work 10 times in a row (not necessarily the same molecule) over a fraction of second.
In summary, from a physical point of view, it is as if the jumper was in an excited state before jumping and then went down in internal energy by emitting this energy which is then converted into internal kinetic energy of the legs parts finally translated into motion of the center of mass of the jumper after "collision" with the ground.
Sorry for the novel ;).
Answer: We can also use the idea of work and energy here. When we jump, the chemical energy in our muscles get converted to kinetic energy that exerts a force on the ground (that using Newton's 3rd law), will trigger a reaction that will 'push' us up- and thus a jump. This resultant normal force = Mass x Distance of jump. When we are jumping, we accelerate initially by F=ma, but then by gaining GPE and thus, a fall in kinetic energy, the speed reduces to 0, in the apex of our jump. Then, we fall- accelerated by gravity and while falling, we have a velocity and thus, a kinetic energy and when we strike the ground, we do work on it, transferring energy into it and thus, force (as the ground has too much inertia to move a lot- but enough kinetic energy can cause this- craters etc.). This force exerted + the weight is the total force we exert once we fall on the ground after jumping. Newton's third law is when A exerts a force on B and B re-exerts the force on A as a simultaneous reaction. When we are standing on the ground, we are 'stretched' by two forces- normal and the weight that cancel out and leave us at equilibrium.
That stone will not bounce simply because it is inelastic and incompressible- the ground would rather crack than let the more incompressible rock bounce. However, dropping the stone on a hard ground- like steel or any incompressible surface will result in the rock shattering due to the collision and momentum or bouncing.


Can't access BIOS after install of ubuntu 12.04

Question: I just got a reconditioned Dell Dimension 4500. I installed Ubuntu 12.04 as the only operating system and now if I try to access the BIOS, I get an error saying utilities partition not found. What do I do?
Answer: You probably erased the system utilities and backup partition, which it probably uses to modify the BIOS settings in a nice, graphical way.  You'll need to contact the manufacturer for recovery CDs and/or a method of restoring the utilities partition.


Ubuntu 12.10 Network Connection menu GUI doesnt work properly

Question: Many a times I have seen When I click on network connection(besides volume icon), I am unable to select any options. When I hover over VPN connections, the list shows nothing. I have added many VPNs. Network menu becomes non responsive to any clicks. This is annoying because I am not able to connect to any of the VPN connections. "Enable Wireless", "Edit Connections" or any other option doesnt work at all. Restarting ubuntu fixes this issue. But problem starts randomly again and restarting my laptop is the only way to fix it. Is this a known bug? Any ways to fix this prob?
Comment: Same problem here. I found if I disable networking from the panel icon, then enable it, the panel icon then shows everything correctly.
Answer: Network management
Try searching "kubuntu network management disabled", this issue is more common in kubuntu, i had it also because i am using a pppoe connection which required the service field from dsl to be empty(and kubuntu 12.04 wouldnt allow it ),installed kubuntu without internet connection and after installation process i did not have any network/internet connections and all connections i made weren't working.
Answer: I'm also having this problem. VPN connections does appear when I restart, but not the connection that I have set up. I have to Refresh the the connection by opening it for Editing and then Saving to get it to appear. Then it works alright.
I think this has something to do with updating.
Comment: That didn't work.


Can grignard reagents react with any electrophillic sites?

Question: Yeah I am confused about the above question. Like since textbooks always say how C atom bonded to Mg is very nucleophillic, I was wondering why it does not bond with carbon atom that is single bonded (not the one in carbonyl part) to one of the oxygen atom of ester? Since O atom is more electronegative than C atom, C atom is electrophillic, so shouldn't grignard reagent also bond with that C atom instead of one double bonded to the other O atom. I always see example where GR reagent attack the carbonyl carbon atom so I was wondering why? Thanks.
Answer: To give you an idea of the nucleophilicity of the two carbons, you may have a look at $\ce{^{13}C}$ NMR data (here for example). These data tell you which carbons have less electron density (the ones which are more deshielded).
On methyl formate, you'd find $\delta_\text{COO} = 161.8$ ppm whereas $\delta_\text{OCH3} = 50.0$ ppm. This should give you a little intuition of how much the electron density is reduced on each carbon, due to the effect of the electronegative atoms. Clearly, the ester-bearing carbon is much more affected, and this accounts for the general behaviour that you encounter.
However, as Ben Norris pointed out, this is maybe a simplistic picture. In fact, it's not impossible to break preferentially the $\ce{COO - C}$ bond. This is called hydrolysis by alkyl-oxygen cleavage (see here).
To get back to the question of Grignard reagent, the problem is also explained by HSAB theory. To attack the carbon which is not bearing the ester, you would generally need a "soft" organometallic compound. I can give you an example that corresponds to what you are asking (reference here: Kawashima et al., Tetrahedron 1989, 45, 403.), but note that this is a special case. What drives the reaction is the opening of a strained ring, and the Grignard is modified by addition of copper halide:

I represented this one in particular to show the regioselectivity (breaking of bond represented in red), but the article shows plenty of examples.
Answer: The thing is, the carbon with that has a double bond and a single bond with oxygen is the most electrophilic. Therefore the Grignard reagent will always choose that carbon every time instead of the other carbon that has only one single bond with oxygen.
Comment: In practical terms, we know Grignard reagents do not react with ethers since ethers are the most common solvents for said reactions. Ethers are not as electrophilic as you think. You cannot just consider the partial charge at an atom, you also need to consider the strength of whatever bond will be broken upon nucleophilic attack.
Comment: I totally agree with you. Ethers are generally very unreactive. However his query is on esters not on ethers.


How many ways to divide 5 different books among 3 children so that each child gets at least one book?

Question:
How can you divide 5 different books among 3 children such that each child gets at least one book? (no book can be divided)

Some one please tell me how to solve this.
Comment: [Inclusion-exclusion principle](http://en.wikipedia.org/wiki/Inclusion–exclusion_principle)
Answer: This is the number of onto functions from a $5$-element set to a $3$-element set.
Here, principle of inclusion & exclusion is useful.
Answer: I would use inclusion-exclusion. Count the total ways to distribute the books. Subtract three times the number of ways to give them to a specific pair. But you have subtracted the ways to gove them all to one child twice (paired once with each of the others) so add them in once.
Answer: use the stars and bars method to see that there are 6 ways to give out 5 identical books.
Of these there are 3 combinations where you give 3 to one kid and 1 to the others and there are 3 combinations where you give 2 to one kid and 1 to the other.
in the ones where you give three to one kid divide by 3! to get the answer of 3*5!/3!=60 and in the one where you give 2 to 2 kids divide by 2(2!) to get 3*5!/2*2!= 90 so therefore there are 150 ways to do it.


Casper Friendly Finality Gadget - Greater degrees of transaction/settlement finality over existing PoW?

Question: With Casper Friendly Finality Gadget, can one expect greater degrees of transaction/settlement finality over existing PoW?
Answer: Casper introduces economic finality to Ethereum. POW does not guarantee finality at all. So yes, there is guaranteed improvement in possibility of finality.

Another unique component of
  the way that Casper does things is that rather than consensus being
  by-chain as is the case with current proof of work protocols,
  consensus is by-block: the consensus process comes to a decision on
  the status of the block at each height independently of every other
  height. This mechanism does introduce some inefficiencies -
  particularly, a bet must register the validator's opinion on the block
  at every height rather than just the head of the chain - but it proves
  to be much simpler to implement strategies for consensus-by-bet in
  this model, and it also has the advantage that it is much more
  friendly to high blockchain speed: theoretically, one can even have a
  block time that is faster than network propagation with this model, as
  blocks can be produced independently of each other, though with the
  obvious proviso that block finalization will still take a while
  longer.
In by-chain consensus, one can view the consensus process as being a
  kind of tug-of-war between negative infinity and positive infinity at
  each fork, where the "status" at the fork represents the number of
  blocks in the longest chain on the right side minus the number of
  blocks on the left side:
Clients trying to determine the "correct chain" simply move forward
  starting from the genesis block, and at each fork go left if the
  status is negative and right if the status is positive. The economic
  incentives here are also clear: once the status goes positive, there
  is a strong economic pressure for it to converge to positive infinity,
  albeit very slowly. If the status goes negative, there is a strong
  economic pressure for it to converge to negative infinity.
Incidentally, note that under this framework the core idea behind the
  GHOST scoring rule becomes a natural generalization - instead of just
  counting the length of the longest chain toward the status, count
  every block on each side of the fork:
In by-block consensus, there is once again the tug of war, though this
  time the "status" is simply an arbitrary number that can be increased
  or decreased by certain actions connected to the protocol; at every
  block height, clients process the block if the status is positive and
  do not process the block if the status is negative. Note that even
  though proof of work is currently by-chain, it doesn't have to be: one
  can easily imagine a protocol where instead of providing a parent
  block, a block with a valid proof of work solution must provide a +1
  or -1 vote on every block height in its history; +1 votes would be
  rewarded only if the block that was voted on does get processed, and
  -1 votes would be rewarded only if the block that was voted on does not get processed:
Of course, in proof of work such a design would not work well for one
  simple reason: if you have to vote on absolutely every previous
  height, then the amount of voting that needs to be done will increase
  quadratically with time and fairly quickly grind the system to a halt.
  With consensus-by-bet, however, because the tug of war can converge to
  complete finality exponentially, the voting overhead is much more
  tolerable.
Answer: No, you cannot reliably and objectively expect greater finality in either systems, as neither can be quantified to a degree that allows meaningful comparison.
Casper aims to provide some form of economic finality by financially punishing byzantine behaviour, while Bitcoin aims to offer probabilistic finality, making a violation of safety statistically unlikely.
Theoretically, Casper should abide to BFT guarantees and provide theoretical consistency if a supermajority is honest, but, in practice, the threshold may require 80%+ honest validators, which may be impossible to prove in a trustless manner, making 100% finality impossible.

So no quantifiable studies are available?

Not that i'm aware of. Casper should provide their finality guarantees much faster than Bitcoin (which doesn't have a mechanism that is considered "finality" other than the 6 blocks confirmations rule-of-thumb,) but neither are 100% guarantees, so I'm not sure how to quantify which provides "greater degree of finality" that holds invariant of time elapsed and is tractable & applicable in practice.
Comment: Thanks! So no quantifiable studies are available?
Comment: updated my answer


Finding the vertices of the ellipse $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$

Question: I am currently reading the topic alluded to in the title of this thread. In my textbook, after the equation has been derived,$$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1,$$it says by finding the $x$-intercepts, $(a,0),(-a,0)$, you've also find the vertices. How do I know that these intercepts are also the vertices?
Answer: Since
$$y=\pm \frac{b}{a}\sqrt{a^2-x^2}$$
it is clear that it must be $\,a^2-x^2\geq 0\Longleftrightarrow |x|\leq a\,$ for the function to be defined, and thus the vertices are in the above interval's extreme points, $\,(\pm a\,,\,0)\,$
Answer: Any affine conic can be put into such canonical equations by a suitable transformation of coordinates, yours is the case of an ellipse with semi-axes of length $a$ and $b$ aligned with the axes $x$ and $y$. To see that the interception with $x=0$ and $y=0$ gives you the vertices $(a,0),(-a,0)$ and $(0,b),(0,-b)$, you may solve one of the variables, for example $$y=\pm |b|\sqrt{1-\frac{x^2}{a^2}},$$ and see that those functions have absolute maximum and minimum at $(0,|b|),(0,-|b|)$ respectively; indeed, the square root is only defined for $x^2/a^2\leq1$ and attains its maximum value at $x=0$. Similarly solving for $x(y)$ you get the vertices of the other axis at $(|a|,0),(-|a|,0)$.


Scientific way to show significance / test hypothesis

Question: I am writing a report to show my results where, if there are more than 3 consecutive English character in a term, that term is noise. For example, "wooooh", "Noooo", etc. I have collected 100 sample and manually evaluated them. May I know what test should I perform to verify my hypothesis? Is it something like ANOVA ?
Comment: What hypothesis? What model? What is it you're actually trying to do, in plain, simple terms?
Comment: ...and how did you collect the samples?
Answer: If your goal is to see if your method works, then you need a sample that includes both "noise" words and "regular" words.
First, you'd need to precisely define those terms. I don't know how you are defining them. "Noooo" is not noise in English text - it is often an extreme version of "No".
You'd have to then figure out how to sample. I'd say you would need some very large selection of random words of English. Do you want spoken or written English? From what type of source? If you include graphic novels and comics you'll get quite a lot of words that meet your definition.  But, since noise words are rare, you would need a large selection - how large? I don't know. Thousands or tens of thousands of words seems like a good range, intuitively.
Then you'd have to decide which of these words is noise and which is not.  Depending on your definition, this might be very hard.
Only then could you analyze your data. I'd say logistic regression would be a good starting point, where the dependent variable would be Noise v. not and the independent variable would be having 3 consecutive characters.


Is there any way to construct a transaction manually?

Question: With Bitcoin you can create an unsigned transaction, sign that transaction and then broadcast it. Is there anyway to do that with Monero? With all the fancy JSON, etc.
Answer: Yes, there is. It works a bit different than in Bitcoin due to Monero specifics involving scanning for outputs with the view-key and checking the spent status by using key images.
First, we assume you have a fully-synced node and fully-refreshed watch-only wallet on the hot computer. Also, we assume you have wallet software on the cold computer (don't need the node, just monero-wallet-cli).

Using watch-only wallet, command export_outputs <filename>. There will be a file with <filename> created in the working folder*.
Copy the file to the cold wallet computer.
Using cold wallet, command import_outputs <filename>*. The cold wallet now has all the outputs and can prepare a signed key image for every one of them (unless something new was received after step 1. It won't display the correct balance because it can't check the spent status of the key images, as it is offline.

--- Stop here if you only want to monitor incoming transfers and don't care to see the correct balance and when something has been spent ---

Using cold wallet, command export_key_images <filename>. There will be a file with <filename> created in the working folder*.
Copy the file to the hot wallet computer.
Using watch only wallet, command import_key_images <filename>*. The watch wallet is now aware of spent status for each output and it shows the correct balance (unless something new was received in the meantime, after step 1.

--- Stop here if you only want to monitor the balance with the watch only wallet. Goto 1. after each newly received funds. Continue for cold spending. ---

Using watch only wallet and transfer command as you would normally, prepare an unsigned transaction. The syntax is the same as if it was a full wallet, but in this case the watch wallet will automatically save the TX to the unsigned_monero_tx file* and a message Unsigned transaction(s) successfully written to file: unsigned_monero_tx will be displayed.
Copy the file to the cold wallet computer.
Using cold wallet, command sign_transfer, to sign and export the transaction. Note that the wallet will look for the file to sign in the working folder*. The signed transaction will be automatically saved to the file* signed_monero_tx and a message Transaction successfully signed to file signed_monero_tx, txid ... will be displayed.
Copy the file to the hot wallet computer.
Using the watch wallet, command submit_transfer and the transaction will be sent to the network. The signed_monero_tx file* must be located in the working folder so it can be found by the wallet. A message Money successfully sent, transaction: ... will be displayed.
Goto 1. because you need the signed key image for the change output.

*Note on folders and file locations, as it could create some confusions. The wallet will look for the files and export them to the folder from where it was started, ie where your command prompt / shell was when you called monero-wallet-cli. It may or may not be the same folder as your actual wallet files or monero-wallet-cli, depending on how you go about it.
For example, your wallet could be on some USB drive like f:\temp\, and your wallet software on c:\monero\ and your shell working folder could be c:\.
If you remain in c:\ with the shell, you could start the wallet by its full path and specify the wallet file location: c:\monero\monero-wallet-cli.exe --wallet-file f:\temp\mywallet. In this case, all the import/export stuff would be read/written to c:\ because that's still your shell's working folder.
It would be probably feel more natural to cd into the wallet folder. Do f: to change drive and then cd f:\temp\. Then, simply start the wallet from that location by its full path again: c:\monero\monero-wallet-cli.exe --wallet-file mywallet. Notice how you don't have to write the full wallet path now as you're already there with your shell. In this case, all the files mentioned above would be written or read from the same folder as the wallet files.
Comment: Looks great. By "copy the file to the wallet", do you mean "to the wallet folder"? It might be confusing.
Comment: Yeah, I could clarify this a bit, thanks for the feedback
Comment: @JollyMort Hi there and thanks for your tut.... I've followed everything but I am having issue broadcasting the transfer. after submit_transfer I am getting 'rejected by daemon with status: Failed' once I go on monerod I'm getting [RPC1][on_send_raw_tx]: tx verification failed? Any ideas? Thanks in advanced!


What is considered to be the pivotal battle between Caesar and Pompey?

Question: Caesar and Pompey's forces battled with one another on numerous occasions during the Fall of the Roman Republic. What is the earliest battle that is commonly accepted as the one where it became clear that Caesar's eventual victory was inevitable?
Answer: Although Caesar's crossing of the Rubicon, which marked the border of his province, was significant in that it marked the start of full on hostilities, it was by no means certain that he would be victorious. According to both Plutarch and Suetonius, Caesar had doubts in his mind as he reached the river, the latter claiming that these doubts were soothed only by the appearance of a divine apparition. Appian also wrote that Caesar had concerns, although those had more to do with the bloodshed that he might unleash, while Cassius Dio does not mention any hesitation.
Misinformation about the size of Caesar's army prompted Pompeius and many of the senators to leave Rome not long afterwards. According to Appian and Plutarch, Pompeius was forced into this action by others in spite of his military experience. Cassius Dio attributes the move to Pompeius fearing that the masses in Rome would support Caesar over him. In terms of numbers, Pompeius had a superior force and recruited further troops in the countryside. It was around this time that Labienus, Caesar's long time deputy in Gaul, switched his allegiance to Pompeius. Even if he had grown distant from Caesar and was afraid of being harmed, as Cassius Dio records, such a move would have been extremely foolish if Pompeius was already looking like a lost cause.
After consolidating power in Italy and Spain, Caesar crossed the Adriatic Sea. However, his supply lines were cut and his defeat at Dyrrachium could well have ended the war in favour of Pompeius. That this did not occur was because the Pompeius was overly cautious, and according to Caesar, fearful of an ambush, having far exceeded his expectations in the fight.
It was only at the final battle at Pharsalus that matters were decided, and even there, Caesar was in a far from solid position. He was short on supplies, only able to acquire them by forage. According to Caesar, such was the confidence in the Pompeian camp that some of its members were already allocating priesthoods and dividing the expected spoils. While Pompeius considered defeating Caesar by starvation, his overconfident subordinates persuaded him to take the field. Pompeius also outnumbered Caesar and possessed the superior cavalry. Caesar's tactics led to the rout of cavalry, however, and in response, Pompeius fled, eventually being assassinated in Egypt.
Comment: Best answer, well explained and *cited*.
Comment: @Drux Can't help you out with any modern literature on this period, unfortunately, as I haven't read any myself. Of the ancient sources, I found Caesar's to be the most detailed and interesting.
Comment: @astabada It would be great if this would be similarly well referenced: http://en.wikipedia.org/wiki/Caesar%27s_Civil_War A key article in such a pitiful state...
Comment: @kubanczyk I did not even notice... I promise to work on it whenever I'll have time (that is next month at the earliest!)
Comment: +1 & what's a good book to read up on the period next to perhaps Ronald Syme's *The Roman Revolution*?
Answer: When Caesar led his army across the Rubicon River, Pompey fled to Greece with his army and most of the Senate.
In the beginning, the advantage seemed to lie with Pompey. Not only did he command a large army, but he also controlled much of the East as well as Spain. Caesar, however, handled the situation masterfully. Finally in 48 B.C., Caesar crushed Pompey's army at Pharsalus in Greece.
Comment: Agreed, but there were several battles afterwards - is Pompey's flight from Rome considered to be the beginning of his downfall?
Comment: @ChrisBunch actually... read my edit.
Answer: Pharsalus was the turning point.  Caesar was out numbered and could easily have lost but was the better general on the day.  Remember that Pompey was considered the better general between the two at the time. After that, it was a matter of time before he finished the civil war. Pompey was later assassinated in Egypt and thus never had a chance to recover from the defeat at Pharsalus.
Comment: Assassination is a pretty hard defeat to recover from.
Comment: @Joe: Okay, I can see how my sentence could be confusing.
Answer: Here is a time line of events of the civil war between Caesar and Pompey (continued by his party after his death)
50 - Caesar enters Italy proper by crossing the Rubicon with his army
49 - Pompey evacuates Italy and arrives in Greece

On route to Spain, Caesar initiates a siege of Massilia, he leaves for Spain, and his subordinates
 successfully end the siege and win a naval battle
Caesar arrives in Spain where he gains a victory over Pompeian forces at Ilerda
Curio, a member of Pompey's party, is defeated and killed by forces loyal to Caesar in Africa

48 - Caesar returns to Italy, crosses over to Greece, and barely wins the battle of Dyrrachium over Pompey

Pompey withdraws to the east, he encounters Caesar at Pharsalus in Thessaly, is defeated, flees to
 Egypt via boat and is murdered by order of the advisors of Ptolemy XIII
Caesar follows Pompey to Egypt with a small force, while sending the bulk of his army to follow via
 Greece -> Asia Minor -> Levant
Caesar backs Cleopatra VII in a civil war against her brother/husband Ptolemy XIII and is involved in
 street fighting in Alexandria from which he barely emerges victorious
Pharnaces II of Pontus, a supporter of Pompey, defeats Gnaeus Domitius Calvinus, a supporter of Caesar,
 at Nicopolis in Asia Minor

47 - After being reinforced by his ally Mithridates of Pergamum, Caesar, along with Cleopatra's forces, defeat her brother outside of Alexandria (Battle of the Nile), thereby ending the Egyptian phase of the war

Caesar gathers his forces, marches north and defeats Pharnaces at Zela in Asia Minor (at which time,
 Caesar allegedly declares, "veni, vidi, vici")
Caesar returns to Italy, suppresses a revolt in Campania, then sails to Africa

46 - Caesar barely defeats his former lieutenant and current Pompeian, Titus Labienus at Ruspina in north Africa

Caesar wins the major battle of Thapsus, in north Africa, against the largest remaining remnants of Pompey's party
Caesar travels to Spain

45 - Caesar defeats the last pocket of Pompeian resistance at Munda in Spain. However, one of Pompey's sons, Sextus,
     escapes to Sicily where he builds up a base of power and resists Antony and Octavian until 35, when he was captured
     and killed in Miletus
Sources:

From the Gracchi to Nero - by H. H. Scullard
http://www.livius.org/
Wikipedia
Comment: Which one do you consider to be the pivotal one?
Comment: Very good answer too.


Can I submit application on the deadline?

Question: If grad schools says the deadline is Jan. 15th, do I have to submit application before Jan. 15th? Or I can still submit on Jan. 15th?
Answer: Most commonly the deadline is inclusive, i.e., "January 15" means that the deadline is "at some moment during January 15". What does this mean can vary:

For online applications, it's usually 23:59:59.
For mailed applications, there are two options and exactly one of them is true:

either the poststamp has to be January 15;
or it has to arrive to the institution by January 15.

For applications you deliver in person, usually the opening hours of the office where you have to bring it apply.

In either case, it should be specified in the conditions.
And please remember that timezones can play a role here, and everything is in the timezone of the institution where you apply unless stated otherwise.

/From comments/

If you doubt the precise conditions, just call them or e-mail them and ask for clarification.

It will cost you less than solving any troubles afterwards.
Comment: I've seen universities with a 5pm online deadline for another time consideration.
Comment: @ChrisC I write "usually" and "it should be specified in the conditions" and "if you doubt ... ask for clarification". I hope this is enough to make sure that what I write is not the definite answer :)


Does my client accept inbound connections?

Question: How can I verify that the Bitcoin client is well connected to the network and is able to receive incoming connections?
Answer: Get your ip from http://whatismyipaddress.com/ and put it in here http://www.subnetonline.com/pages/network-tools/online-port-scanner.php with port 8333. If you can accept incoming connections you should see a result similar to below:
Answer: Just wait 10 minutes or so. If you have more than 8 connections, you are receiving inbound connections.
Comment: And if I only have 8 connections, I'm not accepting inbound connections? I have UPnP turned on + matching router, I thought this would be enough and that I am accepting inbound connections ... but I only have 8 total.
Comment: Is UPnp turned on in router settings (many come w/ UPnp off by default)?
Answer: There is a port checker tool that is not browser based that will allow you to to check to see if the port 8333 is open.  I had a situation with my windows 2008 R2 VPS where i was stuck at 8 connections.  I went into the bitcoin client and unchecked "map using UPnP", shut down the bitcoin client, then went into windows firewall and added bitcoin to accept incoming TCP, UDP connections for the bitcoin-qt.exe.  Then I restarted the bitcoin client, and I had 20+ connections after 10 minutes or so.
I didn't even have to use the port checker tool.


Is Android a 32-bit or 64-bit OS?

Question: The title is pretty much self-explanatory: is Android a 32- or 64- bit OS?  I assume that it is one or another and not both, as that would force both 32- and 64-bit binaries to be hosted on Google Play.  I know that this is a simple question, and that other people have been asking it, but for the life of me I have not been able to find an answer on the web, and there is certainly not one on this SE.
Answer: In the realm of the ARM chipsets which is the common factor, the entire Android stack, from the near-identical kernel based on Linux, are in fact, 32bit, cross-compiled from usually either a 32bit/64bit host environment, the host environment is usually one of the distributions of Linux.  Recommended distribution, by Google, for building and cross-compiling Android is Ubuntu.
The Android run-time library (media, graphics, filesystem, to name but a few) are also 32bit, but as we reach the layer of the dalvikvm, then the number of bits becomes irrelevant as it is at this point, the apks coming from the Google Play Store are native bytecode (A "by-product" of generated Java code compiled into a portable bytecode) which targets the DalvikVM (Virtual Machine) which in turn interprets and translates the bytecode targetting the raw ARM instruction set.
Froyo was the last Android that enabled compilation under a 32bit hosted environment in which it was cross-compiled targetting the ARM chipset.
Gingerbread was the first of "future" Android, back then circa, three years ago, that introduced a requirement to use a 64bit hosted environment in which it was built. There was many hacks to get Gingerbread to be built under 32bit hosted environment.
ICS and JB, and upwards now definitely requires a 64bit environment to speed up compilation and to reduce turn-around time in building.
So to sum up, what you see on the Play Store has no bearing on whether 32bit or 64bit are used and thus irrelevant.
Side note: Typical 16GB RAM/Quad core/64bit Linux distribution, the time it takes to build ICS from scratch, takes 30minutes maximum, had this being a 32bit Linux distribution, it would have taken longer, in fact, may cause a CPU meltdown as there is simply, not enough processing power to churn and crank out cross-compiled code, which is a very demanding and taxing process!
Proof of this.
Pull in any native ARM binary found in /system/bin or /system/xbin, for example, /system/bin/dalvikvm, this is the Dalvik VM binary that is responsible for the upper layers of Java and APKs.
Now, examine the binary by issuing this command: file dalvikvm which gives a summary of the type of file it is, the expected output would be this:

dalvikvm: ELF 32-bit LSB executable, ARM, version 1 (SYSV),
  dynamically linked (uses shared libs), stripped

Notice the reference to 32-bit ELF, and is cross-compiled to ARM and is a binary executable.
Right, moving on, let's inspect a native shared library found in /system/lib, for example, /system/lib/libandroid_runtime.so, now issue file libandroid_runtime.so, the expected output would be this:

libandroid_runtime.so: ELF 32-bit LSB shared object, ARM, version 1
  (SYSV), dynamically linked, stripped

Again, notice, its 32-bit ELF, cross-compiled to ARM and is a shared library.
The key to the host's cross-compilation can be found in the AOSP source, i.e., Gingerbread build originally had a requirement to be built on a 64bit host system, here's the newsgroup linky referring to how to patch the scripts to get it to build on 32bit host which has two patches, found here, for build/core.mk and build/main.mk (combined) on AOSP's Gerrit review.
As a subsequent result, this patch had made its way to ICS's build scripts in which I did have the privilege of compiling ICS on a 32bit platform which took 3 days to build (it was a port of ICS for the Zte Blade). Now, the requirements are ramped up, you do definitely need 64bit host to enable cross-compilation of building AOSP from ICS upwards :)
Comment: I'm downvoting because most of the answer is about what environments are used to **compile** Android, which is completely irrelevant to the question.
Comment: Yes, that's true, and I'm going to post a new answer about the situation today, but the compilation environment has always been a red herring.
Comment: There are now 64-bit ARM devices running 64-bit Android.
Comment: So, you mean that compiling and running an an on 32-bit Android OS takes slower than in 64-bit? Is it a general requirement to be all 64-bit for modern Android OS such as *Kitkat* or *L*?
Comment: @DanHulme This answer was posted near 4 years ago... yes, the landscape has changed a lot since then. :)
Answer: Originally, Android was written for 32-bit processors only: and specifically, 32-bit ARM processors. Later, Intel and MIPS invested a lot into making Android support their architectures too: but still only 32-bit processors. They were able to do this without (many) compatibility problems, because most apps aren't shipped as binaries. Written in Java, they are instead shipped as bytecode, which a virtual machine on the phone compiles to the phone's architecture when the app is run. Some apps include native components, which are shipped as a binary. This is done to make some kinds of apps faster (particularly games), or to let the app access C libraries that aren't available in Java. Those apps can include more than one binary for the native code parts, to allow them to run on different architectures. Even so, the majority of apps are Java-only, so they just work on any architecture.
The above was all true at the time this question (and most of the other answers) was written, but no longer. Lollipop introduced support for the new 64-bit ARM processors (ARMv8) as well as for Intel and AMD's x86_64 processors, which means that Android now supports both 32-bit and 64-bit processors. The Nexus 9 was the first flagship 64-bit Android device. As well as giving access to new instruction set extensions, 64-bit support means that apps can use more than 4 GB of RAM. Most apps won't need that much, but high-end games and photo/video creation software can certainly make use of it: pushing Android towards being a platform for console-quality games (including VR games) and for creating content. Java apps don't need to be updated to take advantage of this, because the virtual machine always compiles them to the phone's architecture, but apps with native code will.
Because ARMv8 is backwards-compatible with 32-bit code (the same way x86_64 can still run x86 code), even apps which include native code for 32-bit processors can still run on 64-bit Android. So an app only needs to be compiled for 64-bit if it contains native code and it wants to take advantage of the higher RAM limit or the new features of the architecture.
Answer: All ARM chips are currently 32-bit. Because of this, Android currently executes all code in a 32-bit environment.
64-bit processors set to launch in 2014.
Comment: That's not exactly a reliable source as this was talking about servers, to quote **"Smartphone is a little bit further off," Forsyth said.**, we're talking about ARM in the context of Android/Smartphones/Tablets.
Answer:
Is Android a 32- or 64- bit OS? I assume that it is one or another and not both, as that would force both 32- and 64-bit binaries to be hosted on Google Play.

Neither actually. Android is a Dalvik VM-based OS, and Google Play hosts Dalvik applications. Dalvik VM itself, like Java VM, is always 32-bit regardless of the bitness of the physical machine.
As you suspected, applications that ships with native binaries and NDK applications must ship with binaries compiled for every architectures it is intended to run at. The most common architecture that Android runs on is ARM 32-bit; however there are also devices that runs on x86 and MIPS.
Answer: Im just guessing but I think this also explains it just simple. It depends on what device you are using, theres four types of os which is ARM, ARM 64, X84 and X84_64. The ARM is the popular 32 bit platform, ARM 64 is also the popular but 64 bit platform, X84 is the uncommon platform and used on Zenfones, same as X84_64 its uncommon and used on Android Emulators. I got this os information on Open Gapps

Is Android a 32-bit or 64-bit OS?


Onion salad goes wet and bitter

Question: I've been going to this indian restaurant that makes this fantastic onion salad, which is essentially small cuts of white and red onion, cucumber, tomato, garnished with mint leaves, coriander leaves and a pinch of garam masala. I tried to make it at home and the results are astoundingly different. They get wet, soft and slightly bitter; whereas the restaurant tastes sweeter, has a bit of a bite and it is dry-ish. Any idea how restaurants make the salad so tasty?
Comment: Do you know for sure that they use garam masala, or is that a guess? Also, what's in their garam masala? Everybody's is different, there's no set recipe. If you use store-bought that may be where the bitterness comes from.
Comment: How long are you letting the salad stay around? Assuming that you didn't use wet vegetables, I'd expect them too not weep any water for hours. Also, are you buying good quality vegetables? Cucumber gets soft a few days after picking.
Comment: Some pertinent questions. @GdD I am sure they use GM as I could tell a few notes of cumin, cinnamon/cassia bark and cloves, but again this is a mild spicing. What do you mean "where the bitterness comes from"?
Comment: @Rumtscho, I normally put it in a plastic take-away container straight into the fridge for flavours to meld and normally served anywhere from 15mins to the next day. The vegetables may not be top drawer (LIDL, asian grocers, etc) but they are fresh enough most often.
Comment: This sounds like kachumber. Look into recipes with that name and try some out to see if any match.
Comment: @WasabiFlux Thanks for giving this recipe a name, the few recipes for kachumber I've looked at don't seem to add anything new to my method. Cheers. :)
Answer:
Cucumber << water, water, water +++
Tomatoes << water, water
Onion << water

Do you see how much water each of those main ingredients contain?
Let's take one at a time.
Onions:-
Fresh onions are not only have a high volume of water, also natrual chemicals that make strong pungent flavour. These chemicals (e.g. Sulphur) work quite well with oxygen in the air, resulting the bitterness.
In order to tone down the flavour and bitterness, soack the onions in ice water.
Another method is to add fresh lime juice immediately after slicing/dicing the onions.
Cucumber:-

Cut and remove the entire section of seeds. Now dice the cucumber.
Remember the little science projects about drawing out excess water from vegetables?
Soak Cucumber in ice water with little salt. (Perhaps you could refrain from adding salt to the final salad bowl, if the quantity used at this point suffice)

Same theory goes for making potato chips. Slice potatoes are soaked in water to draw out that extra moisture. No ricket science here though ;)
Tomatoes:-
Remove entire section of seeds. Dice them and add into your salad.
Garam masala has Fennel and Cineman, that has the sweetness. It's also possible restaurant adds in a bit of sugar. However, certain onion species are sweeter naturally.
To be frank, we don't use garam masala, mint or corriander. Insated you could have the following simple ingridients to make a heaven of a salad, if you may.
fresh :{cucumber, tomatoes, onion, spicy green chilli, black pepper, salt, lime}
Bon appetit!
Comment: Just a clarification, how long to soak the onions/cucumber for?
Comment: Depends on the quantity, I hope you figure out the water volume. Then 15 minutes max would do. Ice water is more suitable for onions. Lemon room temp water is better for cucumber in my experience. Glad to "join" in your kitchen :-)
Comment: I don't understand how plain ice water is going to draw water out of a vegetable. The science of osmosis tells me it won't. You would have to use salt water to achieve that.
Comment: Ice water not equals to vegetable compound, does it? Secondly I don't think anyone wants to draw vegetables till it is withered... please try each of the above if you doubt. And not sure if you noticed "SALT WATER" for cucumber, ice or better lemon water for onions..
Comment: Also, make sure you do not use a blunt or serrated tool to do all the dicing...
Answer: The water is definitely coming out of the vegetables. You could salt them before making the salad, but that will leave you with limp, lifeless bits of onion and cucumber, and that is certainly not what your favourite restaurant is doing. The trick to make this salad crisp is to omit the salt! I'm sure you have experienced horrifying results when you forgot to add salt, and it should be one of the foremost things on your mind, but here the mix of fresh herbs, rich tomatoes, strong onions, and fragrant spices won't need much to boost their flavours. A splash of lemon or lime juice can be added, as one does when preparing low-sodium meals, but if you really can't resist salt's allure, sprinkle some on at the last second - any earlier and the flood gates will open.
The bitterness could be from a number of sources: the spices in your mix (try adding sugar to balance them), the seeds of the tomato, or the cucumber if it's a large field variety (gut them), the type of onions you use (try the sweeter reds or Vidalias, not yellow cooking onions), or the fresh herbs (which bruise easily when cut and will become bitter very quickly once that happens - you can tear them to reduce bruising, and add them just at the end).
Comment: Strangely I don't notice any bitterness from the use of dried mint leaves (although I do buy fresh sometimes and use interchageably) - thanks for your thoughts anyway!
Comment: Thanks Zack, what herbs would these be? I'd normally only use dry mint and fresh coriander.
Comment: If you used dried herbs, then that wouldn't contribute to the bitterness. You should try fresh mint in the summer though, or get a window plant and pull a few leaves off when you want them.

Onion salad goes wet and bitter


Is there a way to "electroplate" wood with copper?

Question: Maybe wood can be coated with copper (II) sulphate first, or roasted in order to form a conductive charcoal (carbon) layer.
Comment: *Electroplate* implies the substrate has some electrical conductivity. Wood's is very poor, hence the difficulty.
Comment: Galvanising usually means coating with zinc. But the short answer is: it would be very difficult to coat wood with copper metal.
Comment: @Gert Didn't know that, i am not a native speaker of english. I corrected for "electroplate".
Comment: @Gert It's difficult indeed, hence the question.
Comment: I like the concept of roasting the wood, but I don't see how you would get a uniformly conductive surface due to the organic structure of the wood. If you coated it with copper sulfate, you would end up losing your conductive layer as it the sulfate salt would likely dissolve in your electrolyte as soon as you put it in. That's why algae resistant paints used on boats need a sacrificial anode to be effective.
Answer: The most common way to apply metals by electrodeposition to nonconductive materials is to apply a "strike" of underlying metal, usually nickel or copper, via a method like electroless plating. In electroless, the electrons for the reduction of the metal ions to the zero-valent state are supplied by a reducing agent in solution:
$$
\begin{align}
\ce{Red &-> Ox + 2 e^-} \\ \\
\ce{Ni^{2+} + 2 e^- &-> Ni^0}
\end{align}
$$
This "strike" coating is then used to provide the electrical connection necessary to apply the metal of interest—here, copper—by typical galvanic electrodeposition methods.
Comment: @Mithoron As long as the wood was dry and in good condition (not crumbling, rotting, etc.), I would expect the strike to hold quite well, actually. You'd want to use seasoned wood to minimize swelling/shrinking, and you'd have to have the wood submerged for the absolute minimum time possible, but I think it has a decent chance of working. The porosity and texture of the surface should be well suited to it. Of course, there could easily be complications I'm not anticipating.
Comment: This solution came to  my mind, but would this "strike" actually hold on to the wood?
Answer: Dip the wood in a solution of ascorbic acid (Vitamin C; orange juice will do) and soap and allow it to soak. Soaking time will vary by wood variant.  then dip the wood in a solution of copper sulfate or another copper salt and soap.  The ascorbic acid will reduce the copper, creating a conductive coating.  This may need to be repeated to achieve a continuous conductive coating. Finally, rinse and dry and you are all set.
Comment: have you tried this? I would be amazed if orange juice has sufficient ascorbic acid to pull this off, and it has loads of stuff you don't need or want. In the UK you can buy a big tub of ascorbic acid powder from Holland and Barret health foods extremely cheaply. There used to be one called Linus Brand and Boots drugstores also used to do it. I know vitamins are far more difficult to come by in Spain, for example, where I have only seen them in licensed pharmacies.
Comment: Homemade electroless, nice! What does the soap do?
Comment: @A.K. I tried this, and it dit not work. I used solutions from tap water which were about saturated (some grains still visible in the vessel) at room temperature. I then dipped pices of beech wood, oak and balsa wood, dried them over night, and then dipped them into the other vessel, over several rounds. I left them in the bath for hours, until the weight hinted that the were fully soaked (it was small pieces). No effect thought. Just a light green colour, which also is what get if you mix the solutions directly.
Comment: Has this been done before?
Comment: I've done it on glass with pure ascorbic acid.
Comment: @A.K.  I got the same result that HannesH did.  The soap I used was Fels-Naptha , a true soap, not a detergent.  The Fels-Naptha gave a pH of about 9 or 10, a good sign as the ascorbic acid reaction proceeds in a basic, not acid solution.  Further complicating things was that the copper sulfate/soap solution gave a flocculant. What "soap" did you use?  What was the pH of the ascorbic acid/soap solution?  Further details would be greatly appreciated.
Answer: Using Marble's Reagent to etch stainless steel, the wood stirrer got coated with copper. Marble's is $\ce{CuSO4}$, $\ce{HCl}$ and water, but I think I added extra $\ce{CuSO4}$.
This isn't technically electroplating, though.
Comment: So that is a mix of hydrochloric acid and copper sulphate? I wonder if the process here is that the wood undergoes hydrolysis from the acid, forming charcoal, which then is a reductand to the copper sulphate.
Answer: It might be possible to evaporate the copper in a vacuum so that it is deposited on the wood. No electric conductivity required.
Here is an example using gold.
YouTube: Gold & Casio Watch - Periodic Table of Videos
And a search found this random document about it
random document about vacuum evaporation
Comment: The question asks specifically about _electro_ plating.
Comment: @pipe since wood is non-conductive, some way to coat wood with something conductive is a requirement for electroplating, and thus well within my question.
Comment: The word electroplate in the question is in quotes which I interpreted to mean "not necessarily literal electroplating".
Answer: Take finely powdered graphene and mix in a water based Polyurethane.
Put a copper nail (or drill a hole and epoxy a wire) into the wood in an inconspicuous area to be plated.
Paint a very light coating over the surface ensuring that you have surrounded the nail (or wire) and make sure the section you want plated has a uniform coating of graphene.
You should be able to plate on this now conductive piece of wood.
Alternatively, there are conductive silver-based paints, but these are relatively expensive.
You're going to have to figure out a way to weight this down to keep it submerged in the electrolyte because it's going to want to float.


What is the origin of twelve Surya namaskar mantra?

Question: I know that there are 12 Surya namaskar mantra that are also described in question here Correct way of Surya namaskar?. But I want to know what is the origin of Surya namskar mantra? Which scripture describes about it?
Comment: ,Please mention the word "origin" in your main question head. It say's 'what are 12 surya namskar Mantras' , but in the body ,you said that 'I know 12 surta Namskar Mantras'.Body and Head of your question is mismatching.
Answer: Sri Swami Satyanada in his book Surya Namaskar - A technique of Solar Visualization says that Sun has different name in each Rashi and these names are chosen for Surya Namaskara Mantras. Sri Swami Satyanada  was disciple of Sri Swami Sivananda.
This is what Sri Swami Satyanada says in Chapter 6 of this book.

Every year the sun passes through twelve different phases, known as
  the signs of the zodiac in Western astrology, and as the rashis in
  Hindu astrology. According to Hindu astrology each rashi has specific
  attributes or moods, and in each of these twelve moods the sun is
  given a different name. These twelve names comprise the twelve sun
  mantras, which are to be mentally repeated in their respective order
  in conjunction with the twelve movements of surya namaskara. These sun
  mantras are not merely names of the sun, every sound syllable
  contained within them is the vehicle of a basic eternal energy
  (shakti) represented by the sun itself. By repetition and
  concentration on these mantras, the whole mental structure will be
  benefited and uplifted.  Although these mantras do not require
  intellectual understanding, a translation of their meaning is given
  below for those with an enquiring mind, as well as for the more
  spiritually inclined who wish to use the mantras as a form of
  attunement with the source of spiritual illumination symbolized by the
  sun.
Comment: @TriyugiNarayanMani Those 12 names are names of Surya used in Surya Namaksara Mantras. Hindu Astrology gives 12 names to Surya based on mood for each Rashi. So, next question is why Sun has a specific name for each Rashi? May be a person well versed in Astrology know this.
Comment: @TriyugiNarayanMani Yeah. Also, we should know relation between Astrology and Surya Namaskara. This is just partial answer.
Comment: OK. So, none of the scriptures mention explicitly 12 names of Surya?
Answer: I will try to give answer to your question about origin of Surya NamskarMantras.-
Their are 108 various names of Surya discribed in ancient scriptures eg. these names can be found in 4 vedas. i.e. Rugved (ऋग्वेद), Atherva Ved (अथर्ववेद) , Yajur Ved (यजुर्वेद) and Sam Ved (सामवेद)
Their are many Vedic refrences for origin of these 108 names , Like , Adityahridayam (आदित्य रहृदयम).
Some of the shlokas are given below -

आदित्यः सविता सूर्यः खगः पूषा गभस्तिमान्। सुवर्णसदृशो भानुर्हिरण्यरेता
  दिवाकरः॥ १०॥
हिरण्यगर्भः शिशिरस्तपनो भास्करो रविः अग्निगर्भोऽदितेः पुत्रः शङ्खः
  शिशिरनाशनः॥ १२॥
Adityahridayam (आदित्य रहृदयम).

Their are also refrences from "Surya Gayatri (सूर्य गायत्री) shlokas ,which contain  some of these 108 names. Some of the shlokas are.

1) ऊँ आदित्याय विदमहे दिवाकराय धीमहि तन्न: सूर्य: प्रचोदयात
2) ऊँ  भास्कराय विदमहे दिवा कराया धीमहि तन्नो सूर्य प्रचोदयात

etc.
So we can say that , the 12 surya Namskar Mantras  origin is from vedas. The 12 surya Namskar Mantras are created using various names discribed in all above mentioned and various other sources. Like Surya Gayatri and Adityahridayam.
Please check the links for more info about 108 Names of Sun and Surya Gayatri and Adityahridayam.
https://en.m.wikipedia.org/wiki/Adityahridayam
http://www.drikpanchang.com/hindu-names/gods/lord-surya/108-surya-names.html
http://bolguru.com/surya-gayatri-mantra-in-hindi-sanskrit-english-with-me
Comment: Thanks for answering but I am looking for scriptural reference.
Comment: @Triyugi Naarayan Mani , Ok we will attempt to find the ref. ,My answer is more general and more or less speculatve. :)
Answer: First of all,this is not the most precise or perfect answer.
But,the 12 Surya namsakara mantras seems to have been originated from the  "Surya Mahatmya: Avatarana, Dwadasadityas, Konaarka and Worship" chapter of the  Brahma Purana.
A "Surya Dwadasa Namavali"(12 names of Surya) as well as a "Surya Asthottara"(108 names of Surya) are included in this chapter.

Dwadashiva pruthaktena taani vakshaamaseshatah, Adityah Savitaa Suryo
  Mihirorkah Prabhaakarah/ Maartando Bhaaskaro Bhanuschitra Bhaanu
  Divaakarah, Ravirdwaadashabhisteshaam Jneyah Saamaanya naamabhih/
  Visnurdhaataa Bhagah Pushaa Mitrendrou Varunyornamaa Vivaswaa
  namsumaam Twashtaa Parjanyo Dwaadashah smritaah/ Ityetey Dwadasha
  –adittaah pruthaktena Vyavastithaah, Uttishthanti Sadaahyetey
  maasthairvaa Dasabhih kramaat/

Meaning-

Normally Surya Deva's names in vogue are Aditya, Savitru, Surya,
  Mihira, Arka, Prabhakara, Martanada, Bhaskara, Bhanu,Chitrabhanu,
  Divakara, Ravi and so on. But the additional names are Vishnu, Dhata,
  Bhaga, Pusha, Mitra, Indra, Varuna, Aryama, Vivasvata, Amsuvan,
  Twashta and Parjanya.

A "Surya Dwadasa nama stotram",different from the one given above, is also found in the Brahmanda Purana.
Even this page seems to confirm the claim that Brahma Purana is the origin of the 12 names/mantras.


Does the number of constituencies in First Past The Post system affect the strength of third parties?

Question: If the number of constituencies in an assembly elected by FPTP was increased from 200 to 500 will that make it easier for third parties to win seats or does it not have any effect?
Comment: Taking the British Parliment has a rough guide it has 650 seats 573 of which are held by one of the two major parties the affect no overall numbers  would be marginal. But it can lead to some very interesting balances of power.
Answer: If fptp constituencies are geographic, increased seats ought to increase representation of geographically concentrated third parties, but not increase geographically dispersed third parties.
Consider the party for Newtown, which has great difficulty winning The Seat for Greater Sydney, but would have a better chance in The Seat for Newtown/Camperdown.
Consider the Party for Redheads which is unlikely to win the seat of Greater Sydney and similarly unlikely to win Newtown/Camperdown.
Answer: Assuming that the increase in seats is uniform and drawn fairly, you can generally expect all parties' seats to increase in proportion to the seats they had before.
Canada added 30 seats to its House of Commons ahead of the 2015 election.  While this increase was not uniform (only 4 of 10 provinces gained seats), the increase of the third party (as all other parties) was still relatively proportional within those provinces.
Here is the official result of the 2011 election, along with Elections Canada's estimate of what the result would have been under the new districts:
<code>|              | 308 seats | 338 Seats |
| Conservative | 166       | 188 (+22) |
|     NDP      | 103       | 109 (+ 6) |
|   Liberal    |  34       |  36 (+ 2) |
|  Bloc Québ.  |   4       |   4 (± 0) |
|    Green     |   1       |   1 (± 0) |
</code>
(Source: Elections Canada)
Answer: Duverger's law says that for a given district, first-past-the-post pushes to just two parties in that district.  If there are two districts, then there could be four parties even under Duverger's law.  That said, our experience has been that in a country like the United Kingdom, with only one type of district, multiple parties are competitive nationally, even if at most two are competitive in any one district.
In the United States, there is a national election (for president).  Further, the Senate and House of Representatives have overlapping districts.  The result has been that in the US, the system has only two national parties with representation.  Only two Senators (and no Representatives) are not from those two parties.  And one of those sought the Democratic nomination for president in 2016.  Both caucus with the Democrats in the Senate.
Someone might argue that the Prime Minister is a national figure.  But prime ministers (at least in the UK) are not directly elected by voters.  They are elected by the legislature and may be replaced at any time, not just at elections.  While the US president is technically picked by the electoral college, this is as a direct result of the popular vote and has elected the majority winner of the popular vote in every election where one existed except one (and there were serious allegations of fraud in that election).  Several times a plurality winner has lost.
There is no evidence that number of seats matters with overlapping districts.  It may make some difference in non-overlapping districts.  But it can make a difference in either direction.  A larger district may hide a minority that a smaller district would reveal.  Or a smaller district may limit a minority to one district that would have still had one in a larger district, effectively reducing their percentage representation.  And with either, careful selection of borders can limit minorities by not letting them have a majority in any district.  Larger districts make that easier.


Add permission to all authenticated users

Question: I have a Site Collection in our SharePoint online tenant. I wanted to give Read permission for everybody in our organization. so in Site Permissions I Clicked on Grant Permissions and typed NT AUTHORITY\authenticated users and clicked ok. However nobody has access to the site collection yet. I thought I have to add NT AUTHORITY\authenticated users to the members group but still nobody has access to the Site Collection.
Comment: I got two suggestions, All users(windows) and All users(Membership). which one is right?
Comment: NT AUTHORITY\authenticated users will only work on-prem. If you type in "All" you should get suggestions to the correct claims user token for all users, for example "All authenticated users" :)
Comment: Probably membership, depends on your setup with authentication. Also this quote " put in a support ticket with Microsoft and found out that our users (who all are external to our network and use Windows Live IDs to authenticate) cannot be included in any kind of "all users" authentication.  I have to enter them all individually into the Visitors group." from http://community.office365.com/en-us/f/154/t/79019.aspx seems to indicate that you can not add external users in any "All...", just a side note
Comment: Are you using ADFS for authenticating users?
Comment: I don't know I have to ask. I will be back. Does it matter?
Answer: You can provide permissions to following groups :

All Authenticated Users: All user accounts which can be recognized by SharePoint Online, both for internal and external.
All Users (Windows) : User accounts from Federated domains.
All Users (membership): All user accounts from Office 365 Online Services.
Comment: To add to this, there's also 'Everyone' and 'Everyone except external users'
Answer: Everyone was what worked for me
EDIT
Everyone is a default group that contains all authenticated and guest users that can connect to your network.
Comment: Can you please elaborate your answer, with details on how your problem got solved..
Comment: can we do this in a event receiver in sp2013? i tried with nt authority \authenticated user, but ti didnt work. please let me know everyone will work


Take image of the disk if Windows are already activated

Question: I am planning to make a Windows installation in some laptops. I ve planned to make installations, new settings etc in one laptop, take an imageof the disk and mount the image to the other machines. The questions is, what can I do if Windows are already activated? It's a bit illegal I think. Any ideas?
Comment: Are these going to be in a corporate environment in a domain? If so, you need to get an SSID changer too.
Answer: If you are not using a Volume Licence Key to be legal you will need to enter in a new key for each machine after you load the image. (at the bottom of the 2nd link there is a command line version so you could script it to make the action of loading the image faster.)
Answer: Before you capture your image, run sysprep. I prefer the OOBE, Generalize, and Shutdown options. These will prepare your image to handle some operations on firstboot.
OOBE: Will ask for computer name, reset SSIDs, initial admin user creation, and a new license key for activation.
Generalize: Will make changes to the HAL to accommodate any driver/hardware differences between the machines.
Shutdown: Boot to your imaging software CD after shutdown and capture the image.
If the computers are all a single brand and came with Windows 7 installed already, you will most likely not have to enter a license key because it will be pulled in from the BIOS/SLIC. This is the case atleast with imaging Dell machines that had OEM Windows 7 installed at the factory.
Sysprep can be found at c:\windows\system32\sysprep\sysprep.exe and you can either choose these options from the GUI or specify them on the command line.
<code>c:\windows\system32\sysprep\sysprep.exe /oobe /generalize /shutdown
</code>