Why do we often have more than one method of slowing down (retarding) aircraft on the ground?

Question: Why do we often have more than (thrust reversers and brake chute) one method of slowing down (retarding) aircraft on the ground?
Comment: I'm not sure your question has enough detail @Heisenberg. Do you mean thrust reversers and brakes, or something else?
Comment: Because the effect is cumulative... I agree with @GdD, there is not enough detail here, you need to explain what you mean, I could just pull the power back and it will slow down, or use brakes, or use aerodynamic braking, etc...
Comment: @GdD thrust reversers and brake chute
Comment: This seems very similar to [this question](https://aviation.stackexchange.com/q/24629/62), although I don't know if it's really a dupe
Comment: Yet some aircraft have no means of slowing themselves at all. The friction of rolling across the ground or the tailskid dragging along is sufficient.
Comment: @TomMcW which aircraft would that be?
Comment: @HarshilSharma Older taildraggers like the Tiger Moth had no brakes. They were designed to land on dirt or grass runways which gave enough rolling friction to stop them.
Answer: I would suspect that it is due to redundance, safety and usefulness in different circumstances.

Thrust reversers are useful to slow down from high speeds, but you wouldn't want to use them when trying to stop at a gate.
Wheel brakes are powerful both at high speed and when parking, but can catch fire if the temperature resulting from the braking gets too high. Also less efficient on slippery runways.
Some (primarily) military aircraft have tailhooks despite not being designed to land on aircraft carriers. The hooks provide an alternative to ejecting and loosing an otherwise good aircraft if the systems powering the brakes fail.
Braking chutes are as far as I know mainly used on aircraft without thrust reversers; these provide an alternative to wheel brakes which is useful in certain parts of the world. Norwegian F-16 and F-35 are equipped with braking chutes as they regularly operate in areas with lots of ice and snow. Braking chutes must be jettisoned before taxiing, and has to be repacked before they can be used again, so they are less common than the other methods.

There are probably other means of slowing down I've forgotten to list. If you are on an aircraft with only one means of slowing down, what do you do when it doesn't work? Having multiple means to slow down means that any passengers or crew has a higher chance of surviving, and also that a failure can result in less damage to the aircraft.
Comment: Air brakes are another method of slowing, but obviously less effective as the speed drops
Comment: Agreed! Definitely for redundancy. I've seen plenty of planes with stuck thrust reversers, all we do is manually close them on the ground and lock out tag out the controls. Pilots then have to go a little heavy on the breaks next time.
Answer: The multiple methods of braking help to stop an aircraft faster, both through providing different means of braking and complementing each other.
The wheel brakes are the primary method of braking on the aircraft. They work at any speed and can provide good braking force depending on the amount of friction between the tires and ground. Brakes convert the aircraft's kinetic energy into heat, and have a limited ability to dissipate that heat. Aircraft may be delayed from taking off to allow brakes to cool down after a rejected takeoff or a short turnaround. Brakes wear down over time and must be replaced. Aircraft that are light and slow may be fine with only wheel brakes, as the other methods are less effective in this case and would add complexity and weight.
Speed brakes or spoilers usually extend from the top surface of the wing. This both increases drag and reduces the lift produced by the wings, and are most effective at higher speeds. Reduced lift means more weight on the wheels, increasing their friction and the effectiveness of brakes. Airliners will typically extend the spoilers immediately after touchdown to increase braking and control effectiveness as they slow down. Aircraft are required to be able to demonstrate a rejected takeoff and stop using only brakes and spoilers on a dry runway. Techniques such as keeping the nose high as long as possible or just holding up elevator can also add aerodynamic braking.
Reverse thrust redirects some of the engine's thrust forward. This provides a braking force and for engines under the wing also helps interrupt airflow over the wing, reducing lift. Jet engines redirect core and/or fan air forward, propellers may change pitch to push the air forward. This can be particularly important on contaminated runways were low friction limits the effectiveness of the brakes. Reverse thrust is generally only used at higher speeds to reduce the risk the debris or exhaust being ingested.
These are the primary methods available on airliners. Brakes are the most versatile but require friction and must be replaced. Speed brakes and reverse thrust use aerodynamic forces at higher speeds to help slow down, and increase effectiveness of brakes. Speed brakes are basically "free", reverse thrust is relatively cheap and effective. Reducing the load placed on wheel brakes reduces temperature and wear; steel brakes deteriorate much more at higher temperatures. Having multiple methods provides some redundancy as well, but when runway friction is poor it's important that they are all used effectively to stop the aircraft.
Drag chutes are another option to slow down. Upon landing, the parachute is released and uses drag to slow an aircraft down. The parachute provides large amounts of drag but must be collected and re-packed after every landing. This is useful for aircraft with high landing speeds where cost is less of an issue, such as fighter jets or the space shuttle.
Tail hooks grab cables on the ground, and the cable provides the braking force to the aircraft. This can stop the aircraft quickly but requires an aircraft designed with a hook that can withstand the braking forces. Hooks are useful on aircraft carriers where space is at a premium, but this requires pilot skill to touch down in the right place for the hook to catch the cable. Hooks can also be used on regular runways for emergencies, where the extended hook will catch the cable as the aircraft rolls past.
Comment: Thrust reversal can also be used to make an airplane move backwards, which is handy when waiting for a tow truck might take too long.
On some types of aircraft, e.g. the C-130, thrust reversal can be used to start another aircraft, by parking them nose to nose.
Answer: When an airplane first lands it will be close to flying speed, the wings will still be producing lift which will keep pressure off the main wheels, making wheel brakes much less effective. Thrust reversers, speed brakes and braking chutes are designed to slow airplanes down until the wheel brakes can be used. They also reduce the landing distance needed, so runways can be shorter.


What happens when Maoki uses Twisted Advance on a teleporting Twisted Fate and Nocturne?

Question: I know Maoki follows flashes and dashes with his Twisted Advance, and does not follow blue pill and tele summoner, but what about TF and Nocturne ults? Does it cancel, take Mao part of the way to the target's new location then stop (like some target spells and autos)? Or is whether or not Mao follows determined by how far away they teleport?
Answer: It is in most cases impossible, Maokai can follow even an ulting TF but the destination must be on the same screen. Check this clip out :


Couldn't Tony Stark cure his palladium poisoning by taking the ARC reactor out of his chest?

Question: In Iron Man II Tony Stark is being slowly poisoned by the palladium in the ARC reactor in his chest. But the only thing that needs to be in his chest is the electromagnet that stops the shrapnel from entering his heart. The ARC reactor power source does not need to be inside his body. I realize that for reasons of plot and character progression, it needed to be done this way. But is there any in universe explanation for why Tony didn't just carry the ARC reactor in a fanny pack and run some wires to the electromagnet? (And don't say it's because of the hole in his chest or to power the Iron Man suit. A person who can build the reactor and armor can cover the chest hole, and the War Machine suit shows the reactor can be built into the suit itself.)
Comment: Because it wouldn't look *cool*.
Comment: Hasn't this been introduced "later on" anyway? I remember watching some animated series during the 90s and I don't remember the reactor being in his chest. Also, just to add: Considering the live action movie, he initially had a car battery outside and later on combined magnet and reactor(really? or is the magnet outside the "tube"?). So my initial question would be "why was there enough space in his chest to begin with?".
Comment: Neutronium isotope of sub-atomic palladium something something functioning at optimal capacity within a given proximity to source of anatomical structural instability? Or something else kinda like that?
Answer: Yes Tony Could have a rig set up with the ARC reactor outside his chest cavity that would still supply power to the electromagnet keeping the shrapnel from killing him.  However, there are two distinct but to Tony valid reasons why he keeps the thing that's killing him inside his chest.

He is deeply concerned with anyone else obtaining the ARC technology.  Keeping it essentially a part of him makes it that much harder for someone else to take it from him.  Granted he did have separate reactors built into his previous suits, however those where under his personally designed security system, with extremely limited access.  The only way the Air Force was able to obtain the Mark II platform in the first place was because Rhodey was the second closest person to Tony with almost unfettered access to his Iron Works.
Tony views the necessity of having the reactor in his chest as a part of his "penance" for creating weapons of mass destruction for so long.  It is a cruel reminder of the lack of morality he had up until the life changing incident that forced him to rely on tech he had written off initially to preserve him from something else he had designed that was slowly killing him.  The fact that the ARC reactor was also slowly killing him was a second level of cruel irony.
Comment: Tony is also more concerned with Style than Substance.  A fanny pack just wouldn't be as cool as a hole in the chest!
Comment: 3.  Do you know how much of a pain it would be to constantly carry around an external power supply?  Even today, real-life medical technology is moving toward internalizing life saving devices (e.g. insulin pumps).
Comment: Not to diss on Tony but couldn't he have insulated the reactor with something eg. plastic. Surely there is no need for direct contact for the powersource/electromagnet to work.
Answer: Tony Stark should be able to figure out the appropriate order of actions.  Step 1.) replace poisonous arc reactor with something that isn't crazy overkill.  Step 2.)  Work on replacing the palladium core without being on a self-imposed deadline.  Step 3.)  Stick new arc reactor back in chest, if you really want to...
He isn't doing it to protect the technology.  He already made suits with external power supplies.
The only valid reason would be that he's suicidal, which isn't completely out of character considering his genius intellect.
Comment: Step 4: have doctor Strange remove shrapnel from his heart.
Answer: In the original comic books, Tony didn't have the ARC reactor in his chest, it was built into the suits' underlayer (which was not included in any of the movies) which had to be worn at all times until he could get the remaining shrapnel removed. So palladium poisoning was never a problem in the comic books.
However, in the movies, the ARC Reactor is depicted as keeping the shrapnel away from his heart using an electromagnetic field (This works because polarization of the shrapnel and the electromagnet were opposites. But the reason it had to have the palladium power source in his chest was because it's an electromagnet. It runs on electricity. Sure, he could've carried it around outside his body, but if the power had been disconnected for just a little while.... well, you saw what happened when the reactor was taken away in the movie. He almost died, and it couldn't have been anymore than fifteen minutes.
If the external power source had been disconnected for that long, there wouldn't have been time to reconnect the power source to the ARC Reactor, seeing as how it was such a complex operation when he had to build it in the movie. It was just easier to have the palladium power source built into the reactor, for convenience and to avoid disaster.
Does that answer your question?
Answer: Also, just gonna point out that if Tony carried it around in a fanny pack or something like that, they likelihood of it coming disconnected on a regular basis would be much higher. In order for him to carry it externally, he'd need wires running from it to what would presumably be electrodes stimulating the heart muscles. If those got yanked or pulled, he'd probably have to have surgery to repair them and they'd become a very easy target for people who wanted to hurt him. (See: The reason Wonder Woman's costume and all costumes with breast-shaped chestplates are dangerous and impractical.)
Comment: From what I recall of the movie, he did have to deal with an external, detachable power source right at the beginning (car battery) under, hm, severely problematic circumstances.  It could well be a reason to give the potential downsides you mention a much greater weight than how it might be managed in more controlled circumstances - either practical awareness of the setup being detachable and vulnerable, or factoring in just plain trauma.
Answer: Because he still needs the palladium to power the iron man suit, and I guess for the sake of protecting the technology and for ease of use (not carrying a giant battery around with him)
Comment: The question points out that Tony has proven able to put external (that is, external to him) power sources in other Iron Man suits
Answer: Think about that fact that h is who he is, he is Tony Stark, maybe he doesn't want it out of his chest because it doesn't look as nice, as well as that he might think that if he keeps in hi sheets he won't have attach and re-attach it when he puts on or takes off a suit
Comment: this appears to be more of a comment than an answer
Answer: The arc reactor simply needs to be inside his chest because it is powering the electromagnet keeping him alive. If he were to wear the reactor in a fannypac of some sort it not only would be weird but impractical and dangerous. Any bad guy could just walk up and pull it away even if it we're under his shirt. Also you've seen the movies for even a short amount of time without the reactor,  Tony goes into cardiac arrest due to not having the arc reactor powering the electromagnet. So if we we're to wrap this answer up with a bow or whatever, tony would just not do this.
Answer: Yep. Big film plot. Without the reactor stark would die, but an alternative power supply to run the electromagnet keeping the shrapnel at bay, presumably he'd have to remain to a tethered power source.
Answer: Simple answer? Plot convenience.
Logically, it's a pretty simple fix. Take out the poisonous palladium, and shove in a few double A batteries. Maybe invent a super long-lasting battery. "this will power your heart for 50 lifetimes, or something big for 15 minutes." So you don't need that much power.
Once you've got the batteries powering the electro-magnet, use the suits with the arc reactor already installed. He could even use the electromagnet to charge the double A batteries in his chest if he wanted to. No palladium poisoning.
The only in-universe explanation that makes sense is the psychological factor. A self-inflicted penance, one that ended in Iron Man 3 when he became more committed to Pepper.
Out-of-universe explanation? Writers hoping you people won't nitpick. It's not a fatal flaw, but a fairly noticeable one. But it's sci-fi, so there's always going to be stuff to nit-pick :)
Comment: To be fair, a strong electromagnet gets through quite a bit of power.  Going by the other answers, it's not literally "powering his heart" like a pacemaker or something (which can indeed run for years off a tiny battery), it's there to power a magnet that holds the chunks of shrapnel in his chest in place so they don't work their way further in and stab him to death.  Don't know how much power that would take, but it might be more than any *real* battery of that size could do.  Of course, Tony Stark can *invent* any battery he likes if the plot requires it, but in this case it didn't.


Is it possible yet to synchronise music to an iPhone running iOS 5/6?

Question: Is it possible yet to synchronise music to an iPhone running iOS 5/6?
I tried it in the Ubuntu 12.10 (Quantal Quetzal) live environment, but I didn't have any luck with Banshee or Rhythmbox.
Is there some way to do it?
Answer: Currently there is no linux software (or library) that can successfully read, write and update an iOS device's music library running iOS 5 or higher. All applications (that I know of), are dependent on libgpod for this functionality and libgpod has not worked properly with the current versions of iOS for some years now, ever since the database version (DBVersion) of the iTunes library within the device hit version 5.
Your best bet right now is iTunes via wine.
Answer: You can try Ubuntu One Music streaming. I'm shifted to subj after almost year not very fruitfull experience with ITunes(vm)/Banshee/Rhytmbox and honestly can say that's a real improvement in my ubuntu/iphone using.
P.S. I'm also dind't have any luck in syncing IOS6 with any player (Ubuntu 12.10).
Answer: Getting the iOS (iPhone/iPad) music player to sync with Ubuntu/Linux based players such as Rhythmbox or Banshee can be a game of cat and mouse as someone else put it. Often there will just not be any way to do it, or only a way that requires level-5 Linux and/or iOS skills. Even if someone manages after many hours of forensic investigation to get it to work, just wait for the next iOS update from Apple changing stuff around or introducing a new "security feature" and – swooooosh - down the hose go all those hours of IT sleuthing.
Instead of indulging Apple in this game one may choose to engage in a little lateral thinking. By-passing/eliminating Apple prop software by replacing the built-in music player with a third-party app is an easy and sustainable way. A rudimentary example would be installing Oplayer on one's iDevice and using its HTTP-based file import feature over wifi to get the files from Ubuntu's music folder. This is not an automatic sync and requires manual work each time one wants to transfer files. It also does not afford us many of the advanced features of, say, an iTunes platform. But at least it works right away and you can have some albums from Ubuntu on your iPhone in minutes. Still, it leaves much to be desired. The dissatisfied user may therefore look for ways to expand on the basic solution and try, say, Dropbox for an automatic sync. Or consider setting up a Samba server on Ubuntu and use the built-in Samba functionality of Oplayer to sync up. Oplayer supports pretty much any and all audio and video formats so unlike with Apple prop software, no need for converting stuff either.
http://www.pocketmeta.com/review-oplayer-best-video-music-media-player-ios-2380/
Alternatively, one may look into several other iOS apps to achieve a different work-around (e.g. look at FileExplorer Free or MewSeek). The one thing to avoid is to try to tackle the problem head-on!
Answer: There are plenty of iPod managers out there on the Software center, just type iPod in the search bar. These are compatible with iPad, iPhone and iPod classic. They will happily synchronize your music and do way more for you. I reccomend gtkpod, but you can choose whichever you like.


Amazon EC2 Load Balanced & Auto Loaded Cluster - What happens to browser sessions?

Question: Assuming a cluster of webservers on EC2 with both Elastic Load Balancing and Auto Loading (meaning instances start and die based on demand), can someone tell me what happens to a user's browser's session? Is the load balancer smart enough to track sessions? Or at least smart enough to send a particular user's requests to the same instance consistently? Or do I have to find and manage a solution to this problem myself?
Answer: Need more information, it depends on how you are implementing your sessions. Although some load balancers are 'smart' enough to redirect based on sessions, relying on that really just means your architecture is broken in the first place.
Ideally you want either a centralized or distributed session store. Good options are a centralized database like MySQL, or something distributed like memcached.  You probably want to start with the database, and move to memcached if you really start gaining traffic.
What framework or language is your application using?
Comment: Your framework should be handling the session, not EC2. Configure JBoss to store the session in the database, and you will have no worries :)
Comment: The platform is JBoss with MySQL.  JBoss supports clustering through multicast (not supported on EC2).  Putting the session in the database is an option. Another possible option is having the JBoss instances cluster through the use of a 'gossip' server.  My question is to what degree can I rely on EC2 for session handling.
Answer: No, ELB is not a sticky session based load balancer.  It is a 'not strict round robin' based load balancer that does not take into account your session scheme.  Some details are investigated here: http://clouddevelopertips.blogspot.com/2009/07/elastic-in-elastic-load-balancing-elb.html
If you want to use elb then you need to make sure your session scheme can deal with the requests being routed to any of the servers in the elb pool at any request.
Answer: You have two options.
Your best option is to do as anveo said. Using a centralized session store means that they can hit any one of your servers and still have their session. You can spin up and terminate instances without worrying about the effect on the users.
Another option is the use the stickiness option of the ELB. You can create session cookies and the load balancer will route a session cookie to the same instance each time. The problem with this is that you can not freely kill instances because people will lose their sessions (if that matters). The only upside to this method is that it is extremely simple to implement. And losing sessions isn't that bad normally. The user would just log back in again.


Invalid GLSL on some machines

Question: I'm writing a game engine using OpenGL 4.3 using gcc 5, mainly to teach myself graphics programming.
Initial development was on my Surface Pro 3 using mingw-w64 and worked like a charm.
I've decided to move to my desktop, which is running two GTX 670s, and both Windows and Arch Linux. I've made sure that I have the latest NVIDIA drivers installed on both operating systems, but am having issues with my vertex and fragment shaders. All I know is that neither system compiles the shaders, but the OpenGL Reference Compiler simply issues a warning saying that OpenGL 4.3 might not be fully implemented. I've also tried downgrading all the way to OpenGL 4.0, but this doesn't seem to fix the issue.
Below are the shaders that I'm currently trying out. Hoping someone more experienced than I can lend a hand?
shader.vert:
<code>#version 430

layout (location = 0) in vec3 vertex_position;
layout (location = 1) in vec2 vt;

uniform mat4 cam_view, cam_proj, sprite_matrix;

out vec2 texture_coordinates;

void main()
{
   texture_coordinates = vt;
   gl_Position = cam_proj * cam_view * sprite_matrix * vec4(vertex_position, 1.0);
}
</code>
shader.frag:
<code>#version 430

in vec2 texture_coordinates;
layout (binding = 0) uniform sampler2D tex;

out vec4 frag_colour;

void main()
{
   vec4 texel = texture(tex, texture_coordinates);
   frag_colour = texel;
}
</code>
Thanks in advance :)
Comment: If the shader doesn't compile, its error log can be read using glGetShaderInfoLog()
Answer: http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-670/specifications
Nvidia homepage says only 4.2 is supported.
Check the error logs and for any other opengl error and fix them if any.

Invalid GLSL on some machines


using Swing components in javafx if they're not in the NetBeans javafx palette

Question: I'm just getting started with javafx in NetBeans, and I have it doing simple stuff (windows with buttons + the like) but would like to try something slightly more realistic.
The "Swing/AWT Components" palette has a whole bunch of stuff that the "JavaFX Script Code Clips" palette does not (it has Button, CheckBox, ComboBox, ComboBoxItem, Label, RadioButton, Slider, TextField, and ToggleButton). How do I add stuff to this palette?
I would like to try using some of the components in org-netbeans-swing-outline.jar

edit: Aha. I was missing the point somewhat: there are only some javafx-wrapped Swing components available in javafx.ext.Swing.*, so if you want one of the other Swing components you have to wrap them yourself.
Comment: what version of netbeans are you using?
Answer: aha, I figured out what I needed to do:
There's a way to wrap Swing components into a javafx component using javafx.ext.swing.SwingComponent.wrap()


What are the best tips for developing a framework to write a (systematic) review paper?

Question: Perhaps, this is a meta-level question. Most review papers narrate the story of the field/problem or summarize a large but focused body of literature. The authors are usually senior level faculties with years of experience in the field. How these papers are being reviewed and what is the formalism behind accepting or rejecting them? Many such papers fail to present a framework/criteria/dimension for the field (maybe due to complexity), but is there any effort targeted to develop reviewing skills for young researchers to follow?
Comment: Can you please reduce your question to contain only one question (preferrably that which was already answered)?
Comment: I think the main question "What are the best tips for developing a framework to write a (systematic) review paper?" is focused enough. and one of the answer has some citations to tutorials of "systematic review". I don't believe my question is limited to "systematic reviews" and I think even many "literature review" part of papers suffers from same lack of depth.  I tried to clarify in description that is there any basic steps to develop such frameworks or categorizing different methods. all being said I am open to suggestion if the title needs to be changed.
Answer: I too find it frustrating that so many literature reviews are so unsystematic.
There are efforts underway to improve the quality of reviews, and to develop these skills in early-career researchers. We like our students, where possible, to write a review article as a early part of their PhD. The medical field has for many years been honing the quality of reviews, and there's much that other fields can learn from it.
We have had a Q&A about systematic reviews earlier, and there I listed three relevant books. The most significant of these, as far as your question is concerned, is Doing a Systematic Review: A Student's Guide - Angela Boland et al - it's primarily aimed at Masters students, and also makes for an easy-to-read introduction to the field for anyone.
Comment: great references.
Answer: When referring to a Review, I am thinking of a Topical Review, PhD Tutorial, or Colloquium such as those published in The Review of Modern Physics or the Journal of Physics B.
It is true that most publications leave a new graduate student without a sufficient introduction to the topic; however, this should not be the case with a Review. As a grad student, I recall being frustrated reading regular journal articles. Then I remember my elation while reading the introduction of my first review article. The clouds of confusion parted as the author explained few-cycle laser pulses in "plain physics."
Review articles are arguable the hardest to write. First, the author must be intimately familiar with the topic and be able to weave a disparate group publications into a cohesive story. The Review's introduction must present sufficient motivation, provide a historical context, and create a structural outline for the topic at hand. Next, the author must clarify and distill the important papers, and include lesser papers as they advance the story. Since Reviews often include over 200 articles in their reference list, this can be quite a task. Finally, a good Review will highlight new applications and open question.
In addition to the above structural criteria by which a Review should be judged, see the selected answer of this post for political advice.
To summarize and answer your question:

Why don't junior scientists write such Reviews, and why aren't there efforts train them?

Before learning to run one must learn to walk, and before writing a Review one must learn to write a regular article.
As you mentioned, senior faculty often write Reviews because they have the most familiarity with the literature, connections, and experience.
The best training for junior faculty is gaining a familiarity with: the literature, the publishing process, and colleagues.


Change Icon Size in Unity 2D Launcher

Question:
Possible Duplicate:
How can I make Unity 2D launcher icons smaller?

Is it possible to change the icon sizes of the buttons in the launcher used in Unity 2D?
Answer: At this moment, here is no way to change the launcher width in Unity 2D, as you can read here:
https://answers.launchpad.net/unity-2d/+question/158873
https://answers.launchpad.net/unity-2d/+question/141757
I suggest to register to this bug on launchpad, that is the related feature request:
https://bugs.launchpad.net/unity-2d/+bug/789638
Note: the are few other options you can choose, see question How do I configure Unity 2D?
Answer: You might actually not need to be using Unity 2D.  I found that if I tried to log in to just ubuntu I would get just the background but no Unity 3D; 2D log in worked fine. However if after downloading Gnome-shell I could log into "Classic no effects" then in a terminal window type "Unity" and I can get the Unity 3D shell working that way and be able to change icon size etc from compiz.  I'm sure there's a more elegant way of doing this but the workaround worked for me.

Change Icon Size in Unity 2D Launcher


What is the difference between "c'est pour cela" and "c'est pour ça"?

Question: Is it about the meaning of the sentence or the type of name that comes after it?
Answer: "Ça" can replace "Cela" in all sentences, it means the same thing.
"Ça" is more used in familiar language and "Cela" in formal or literary language.
Answer: ça is the contraction of cela just like c'est is the contraction of cela est.
However ceci and cela are differents like this and that.

What is the difference between “c'est pour cela” and “c'est pour ça”?


How does the Fire Giant Dreadnought's Shield Charge actually work?

Question: If the Dreadnought misses his first attack is he stopped from further movement? Also, if the PC makes the strength save does that stop the dreadnought from further movement?
Comment: Hi, welcome to RPG Stack Exchange! Thanks for following up on that comment and asking this in a new question. Check out our [tour] to see how we work here, and when you reach 20 rep, you can join us in [chat].
Answer: Nothing in the Shield Charge ability's description says that its movement is stopped by its attack during the Shield Charge. From its statblock:

Fireshield. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 22 (4d6+8) bludgeoning damage plus 7 (2d6) fire damage plus 7 (2d6) piercing damage.
[...]
Shield Charge. The giant moves up to 30 feet in a straight line and can move through the space of any creature smaller than Huge. The first time it enters a creature's space during this move, it makes a fireshield attack against that creature. If the attack hits, the target must also succeed on a DC 21 Strength saving throw or be pushed ahead of the giant for the rest of this move. If a creature fails the save by 5 or more, it is also knocked prone and takes 18 (3d6+8) bludgeoning damage, or 29 (6d6+8) bludgeoning damage if it was already prone.

Judging from that, the shield charge lets the fire giant dreadnought move up to 30 feet in a straight line, including through the space of any creature that is smaller than Huge. The attack is essentially incidental to the move; if the target succeeds its Strength save, it is unaffected.
You could flavor this as if the character that makes the save is actually holding the fire giant dreadnought back just long enough to move himself/herself out of the way, or however else you want to describe it.
The dreadnought could, of course, choose to stop before the end of the 30 feet, since the Shield Charge doesn't specify that it must move the full 30 feet.
Comment: @AntiDrondert I would say no, sentinel sets speed to 0, this is an action that moves you, however it does not rely on your speed.
Comment: I know this is the topic for another question but can this charge be stopped by *Sentinel* feat?
Comment: The Sage Advice Compendium does have an answer about a tangentially related question: "**What happens if a grappled creature (or the grappler) teleports via Benign Transposition, Shadow Step, or another effect?** The grappled condition ends if an effect removes the grappled creature from the reach of the grappler (PH, 290)." This allows the grappled creature to get away even if their speed is 0 before the action. So ultimately, as long as the Dreadnought's action does not rely on its speed (or use its regular movement), @Baergren would be correct.
Answer: First, it does what it says it does:

Shield Charge. The giant moves up to 30 feet in a straight line and can move through the space of any creature smaller than Huge.

This is the part that says how the movement works - the rest is about the Fireshield attack and its effects on the target: it doesn't change this part about the giant's movement. It can move 30 feet in a straight line so long as it doesn't enter a Huge or larger creature. In normal movement, you can move through friendly creature's spaces but this specific action says you can only "move through the space of any creature smaller than Huge" i.e. friendly creatures can't get out of your way like they normally can. It doesn't change the fact that the giant still cant voluntarily end its move in another creature's space.
Second, remember that under the action economy, this is an action for the Dreadnought so they still have their movement, possible bonus action and reaction available.
Before and/or after this action (where it has moved anywhere from 1 to 30 feet or 5 to 30 feet if playing on a grid) it can still take its normal movement which can be in any number of directions.


Why is our Original Gravity low?

Question: When brewing from an extract kit we always seem to be low in the Original Gravity department. It's usually not a lot -- something like 1.055 instead of 1.060. What might be causing this to happen? Is there anything we can do to check and adjust before the fermentation begins?
Comment: are you measuring your gravity at 60 degrees or adjusting the gravity if the temperature is higher?  And is the volume at 5 gal? (or higher or lower?)
Comment: If it's constantly low, you should also check your hydrometer (assuming that's what you're using to measure SG) to make sure the paper scale inside hasn't slipped.
Answer: If you're doing a concentrated boil, it's possible you're just adding too much water to the fermenter when you finally put it together.  For a five gallon batch, a difference of about half a gallon of water will cause that exact difference in OG.
If you're doing a full wort boil, it could be the difference between boiling with the lid on and boiling with the lid off.
Comment: Yes this. Or you could not be boiling long enough or vigorous enough.  a lower OG indicates you have too much water for the given fermentable sugar content of the recipe.
Comment: Another note, the wort will take up less volume as it cools, so if you measure it as 5 when it's boiling, it'll likely condense to 4.X after it cools.  This might be the case if your OG was higher than the recipe, for example.
Answer: The usual problem is that a brewer will do a partial boil and top up the fermenter with water.  Since wort, containing sugar, is heavier than water it will sink to the bottom of the fermenter.  When you take the sample, you're getting watered down wort from the top of the fermenter.  When doing a partial boil, it's usually easier to compute the OG than to measure it.
Comment: I think this explains the same issue I just had trying my first kit. The kit suggested the OG was going to be 1.042 for a 23 litre batch, but I was getting 1.034 with only 20 litres (so was actually hoping it to be little higher than the 1.042). I didn't want to mess around too much with my wort, so I just pitched the yeast and left it for a few hours. Just gone back and given it a stir and took another reading and got 1.038. I suspect I have some thick liquid stuck to the bottom or maybe I didn't dissolve all the granulated sugar.
Answer: If you've not adjusted for the temperature of the wort then this might explain a few points difference. Check what temperature you hydrometer is calibrated to (usually 20°C/68°F) and then use this calculator - http://www.brewersfriend.com/hydrometer-temp/ - A 40°C wort would explain a 1.060 gravity being read as 1.055
Another possibility is the kit is just overstating the potential OG. My kit suggested 1.042, but I have just put my ingredients list into http://www.brewersfriend.com/allgrain-ogfg/ and got an OG calculation that was very close to what I measured.

Why is our Original Gravity low?


In computer networks, when is a MAC address used and when is an IP Address used?

Question: MAC address and IP address are used to uniquely identify a computer. When is an IP address used and when is a MAC address used?
Comment: this sounds like a homework question.
Comment: :) This isn't any homework question, this has been a long standing doubt for me :)
Comment: yeah, sounds like one i got when i was studying networking.. curious. :P
Answer: MAC (Media Access Control) addresses uniquely identify Ethernet network cards (or PCs with built in Ethernet). Although it's true that every computer that uses Ethernet has a unique MAC address, not all Internet connections are made over Ethernet. Also, MAC addresses in a particular local network are not similar in any way, so one can't use them to decide that a particular machine is "nearby."
IP addresses uniquely identify computers on the Internet, or on a local intranet. Computers on the same local "subnet," such as those on a particular local network, will share part of their IP address. For instance, computers in my house intranet are part of the 192.168.2.x subnet, with IP addresses like 192.168.2.6 and 192.168.2.22. The router that connects my house to the Internet has the IP address 192.168.2.1. That router also has a true Internet IP address, and performs NAT (Network Address Translation) to allow connections from computers inside my intranet to reach the outside world... but blocks incoming connections for security.
Answer: To communicate in an Ethernet network, MAC addresses are used. Ethernet frames (packets) don't know anything about IP addresses. ARP is used to find out the MAC address of a host on the local network. IP addresses belong to a higher OSI layer and are used to identify computers on one or more networks as the Internet is not one network, but a system of many networks.
Answer: A MAC-Address and an IP-Address are two completely different things.
A MAC-Address is an Unique Identifier of the network interface (stored in the hardware), and the IP-Address is the assigned (from a router f.e.) network address within the network.
Answer: In short:
An IP address is either given by a DHCP server (router) or you give it yourself. A MAC address is the hardware identifier for the NIC. This is static but you can alter it if you whish.
Your IP address is important since your network relies on it. Your mac isn't unless your ISP wants only one MAC address to connect with them over the modem. (totally offtopic though) Some people also use MAC lists as a security layer but this is highly insecure.


Is it possible to write draft post on TEX.SE?

Question: Is it possible to write draft posts on TEX.SE? It could be useful when you are interrupted and you don't have the time to finish your question/answer. In such cases, AFAIK, I don't think it is possible today to save the draft and finish later. (?)
Comment: The draft you write in the big white text boxes is saved every something-ty seconds or so on the server and will be shown again if you revisit the answer or question. [It's 45 seconds.](http://meta.stackexchange.com/a/66238)
Comment: Yes, please turn that into an answer so I can downvote it.  This feature of the AJAX is not something I would rely on to save my work.  In particular, I don't think it's suitable for "save the draft and finish later".  More just to make browser back/forward actions work sensibly.
Comment: @Speravir It's the spirit of the machine. SE.TeX does not like draft of false answer :-)
Comment: Nice, I didn't notice. I would be glad to accept this as an answer if you convert it.
Comment: @Qrrbrbirlbel (what a name!) And it allows to save only one draft. What when you have two or more question in mind?
Comment: In addition to Ben: It already happened to me, that a draft disappeared without interaction by me, I suppose an unwanted cookie delete on my machine. But funnily it must have been artificial intelligence: I later realized, that my answer would have been wrong. :-)
Comment: @ppr Yes, seems so …
Answer: Technically, you're allowed to try whatever you want in the Sand-Box. The formatting mark-down for questions and for answers is the same, therefore you can make your draft an answer in the sand-box. Just start it with something like:

This is a draft of a question for the main site, I'll use and remove it before December 25, 2013.

This should be IMHO fine. It's good to add the date there, and it's good to delete it once you don't need it anymore.
However, I'd like to know a moderator's opinion on my suggestion before you use it.
Comment: ok but it's still a workaround and not a proper draft management system.
Answer: The author of a post (question or answer) can undelete his own post, as long as he closed it himself.  If the community or a moderator voted to close/delete, then they will have to agree to undeletion.
Also, deleted posts don't show up in one's user profile, so it's necessary to save the URL to continue editing.
Still, this is an option for saving multiple drafts that aren't yet ready for public viewing.
Comment: However, on some sites (not here), doing this can lead to getting question-banned, which is a bot-based ban and can't be manually overwritten by the mods, only the higher powers can do that.


Repeat process for image download

Question: I am using Kingfisher framework to download images from the web and cache them. I have an array with a lot of Facebook id's, and the code needs to download the picture of each of them. Right now, the code downloads the picture for newArray[0], but it should do that for every id stored in the array.
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return newArray.count

}

override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("collectionViewCell", forIndexPath: indexPath) as! CollectionViewCell
    cell.imageView.kf_showIndicatorWhenLoading = true

    let URL = NSURL(string: "http://graph.facebook.com/" + newArray[0] + "/picture?type=large")!
    cell.imageView.kf_setImageWithResource(Resource(downloadURL: URL), placeholderImage: nil, optionsInfo: nil, progressBlock: { (receivedSize, totalSize) -> () in

    }) { (image, error, cacheType, imageURL) -> () in

    }
    return cell
}

}
Any idea how I would make it loop trough the code for every id and display it in the collection view?
Any help is appreciated, really! Thanks!
Answer: You can use indexPath.row in your method.
Example:
let URL = NSURL(string: "http://graph.facebook.com/" + newArray[indexPath.row] + "/picture?type=large")!

Repeat process for image download


Does Windows Phone support app widgets?

Question: Does Windows Phone support app widgets like Android phones do?
Comment: What's an "app widget" - it might be useful to include context of the functionality you're wanting to see on your Windows Phone?
Answer: No and there's no need.
One of the key features of the Windows Phone platform are Live Tiles, which provide a snapshot of information on your Start Screen. We have Live Tiles that will deliver weather information, appointments, TV shows, and even gaming progress.
Personally, I like how I can glance at the weather and appointment Tiles to see what the current temperature is or how long I have until the next meeting.  Other than that, I generally use the Live Tiles as a shortcut to the many apps I have pinned to my Start Screen.
I cannot think why would anyone want widgets when we have live tiles

Does Windows Phone support app widgets?


Bohr's model of an atom doesn't seem to have overcome the drawback of Rutherford's model

Question: We, as high school students have been taught that-because Bohr's model of an atom assigns specific orbits for electrons-that it is better than Rutherford's model. But what Rutherford failed to explain was why electrons don't emit EM waves & fall into the nucleus. I don't see how the introduction of 'atomic orbitals' overcame this defect. Can't it still radiate EM waves?
Answer: Classically emission is continuous and the electron would need to occupy a "in between" energy level for a while, and that is forbidden in Bohr's scheme, so the emission can't be allowed to happen.
This doesn't really explain why it can't happen, but that's phenomenology for you: you keep lining up facts until your kludge (1) gets the right answer and (2) might be pointing at a better "real" theory.
Answer: Unfortunately, nobody reads Bohr nowadays so Bohr's arguments are not understood and transmitted. Modern quantum mechanics is more complete and superior as a physical theory to the old quantum mechanics, so the omission is perhaps understandable, but it is not forgivable.
Bohr's ideas explain the stability of H-atoms in a reasonable way, which is also correct in the modern theory. In modern quantum mechanics, it is obvious that there is a ground state for the electrons, because if you confine the electron to a box of radius a, it has a momentum of order ${1\over a}$, and therefore a kinetic energy of ${1\over a^2}$, while the negative potential energy is only ${1\over a}$, so there is a minimum distance, beyond which confining an electron costs energy. If you restore the factors of m and $\hbar$, this distance is a small multiple of the Bohr radius.
Bohr didn't have the uncertainty principle, but he made an argument which gives the same basic law. So Bohr explained the stability correctly in the context of semiclassical quantum theor, and his explanation is roughly isomorphic to the modern one.
Bohr's argument
The classical orbiting electron radiates EM waves. The frequency of the radiation emitted is equal to the classical orbital frequency (assuming small back-reaction, which is reasonable, since the electron is nonrelativistic), and the energy can be radiated in arbitrarily small increments.
In Bohr's model, the radiation emitted has to come in lumps, associated with discrete jumps between orbits of different frequency. The size of the energy lump is hf, where f is the frequency of the photon.
In classical mechanics (and for large orbits), there is only one frequency to emit with, and this is the orbital frequency (and integer multiples of the orbital frequency, corresponding to higher harmonics). But in Bohr's quantum mechanics there are two orbital frequencies associated with every jump, the initial frequency, and the final frequency, and the basic question is which frequency is the correct frequency of the emitted radiation?
The question has no real answer for small quantum numbers, since the semiclassical approximation breaks down. But Bohr assumed it is some average of the initial and final frequency. Let's say:
$$ f_0 + f_1 \over 2 $$
once you know the frequency of the outgoing radiation, you know the energy quantum, and therefore the energy spacing. Bohr used this rule to figure out the level spacings in the atoms, and he knew the rules were only correct for large quantum numbers.
The classical frequency of a classical orbit at radius R goes as Kepler's third law:
$$ f = {1\over T} \propto {1\over R^{1.5}}$$
The binding energy is of order the potential energy:
$$ E \propto {1\over R}$$
Note that E is the negative of the negative energy, so E is positive. Therefore
the frequency f of the classical orbit obeys:
$$ f \propto |E|^{1.5}$$
Assuming we are at a high binding energy, and we make a transition from an initial frequency to the final frequency, the energy emitted is proportional to the average of the initial and final frequency, so the frequency of the emitted radiation is
$$ f= {1\over 2} (|E_i|^{1.5} + |E_f|^{1.5} ) $$
and this frequency average times h must be equal to the binding energy difference between the orbits:
$$ (E_f - E_i) $$
When $E_i $ is big enough, there can be no solution for $E_f$, because the frequency rises faster than the binding energy, and the two curves never meet. This means that there is a ground state, from which no radiation cannot be emitted.
This argument is superficially different from the modern argument, using uncertainty, so it is important to check that it is essentially equivalent in order of magnitude to the modern argument.
The modern argument says that the size of the p for small x is roughly reciprocal, so that if you consider a classical orbit witht the same energy as the ground state, the momentum and the position in the orbit are such that the area enclosed by the orbit in phase space is order h.
The frequency argument says that the spacing between adjacent levels obeys the rule
$$ \Delta E = h {2\pi\over T} = h {\partial H \over \partial J} \approx H(J+h) - H(J) $$
where J is the classical orbit, so it says that J is quantized in integer steps of h. The statement that there is a lowest energy level  is the statement that a orbit close enough to the nucleus encloses an arbitrarily small area in phase space. This is not completely obvious, because the momentum is getting large, but it is true, because the momentum is not getting large fast enough to compensate for x getting small, so that the area enclosed is convergent.
Answer: Ron Maimon's answer is very good and I agree with him, but I would like to point out that Bohr's model  is not completely consistent with classical electromagnetism. On the one hand, the electron does not radiate as dmckee and Ron have explained. But, on the other hand, in Bohr's model the electron is a pure particle in a closed orbit and it is therefore accelerating. So according to classical electromagnetism it has to radiate. Thus it seems to me that there is not goof agreement between Bohr's model and Maxwell electromagnetism.
In "modern" QM, the electron is however described by a probability wave function. And if one links the density current of probability to the density current of charge —what makes sense—, then classical electromagnetism tell us that the electron does not radiate because the density current is time independent in stationary states.
Comment: Of course you are right, but when asking about history, I think it is good to be respectful of the historical authors. Bohr knew that the Maxwell theory had to be modified, and he had some ideas about how this works in QM with minimal damage to Maxwell. This was the failed 1924 Bohr Kramers Slater theory, which had classical EM waves causing distant transitions in atoms. It is essentially semiclassical QED without photons, one atom makes a field, another atom responds. Some of the ideas were unchanged in modern QM, but the lack of photons made it that energy couldn't be conserved.
Answer: You are right, and quantum mechanic does not explain it ether. You will have to study quantum electrodynamics to have the picture right. It is a common error found in introductory books to say that classical mechanics failed to explain the stability of the electrons while QM did. The true story is that in classical mechanics, if one introduces the radiation emitted by the electrons then the orbit is instable and in QM ones does not introduce the radiation emitted by the electrons.
However, the results obtained by QM were so astounding that people knew they were on the good tracks.


transfer files from Mac to nexus 7 via bluetooth?

Question: I forgot the USB cable and I have some files on the Mac that I would like to transfer to my nexus 7. Is it possible to do this via bluetooth? Is there an app that can do this?
Answer: Provided both the Android handset and your Mac share a common wifi connection (same AP that allows client-to-client connections):
Install an FTP server or a webserver app that allows uploading:
For example Airdroid. It allows file-uploading via drag&drop even. You'll find your uploaded files in airdroid/upload in the SDcard folder.
Answer: It's not Bluetooth, but try my Open Source project cross copy for inter-device copy and paste:

browse to http://cross-copy.net on both devices
choose the same code word to establish a connection between the devices
upload the files on the Mac
a download link for each file will appear on the page of the Nexus 7


Is the US Government being shut down affecting the deadline for the debt ceiling?

Question: The US government is shut down, and has been for one week as of writing. The government is also supposed to require a debt ceiling increase by Oct 17, or else the government will fail to be able to pay its debts. How is the first crisis affecting the second, specifically in the deadline? If the US Government is still shut down on October 17, will the debt ceiling still be reached?
Answer: For the most part, I would say that the first crisis (the shutdown) is affecting the second (debt limit) more politically than technically. Although, I suppose that without a budget to operate on, the Treasury may in fact have more cash on hand then it otherwise would, thus allowing the actual point at which it runs out of money to be pushed back (albeit a small amount).
As for the debt ceiling being reached I think it already has (someone correct me if I'm wrong) and what the Oct. 17th deadline is referring to is the point at which the government runs out of cash to pay ALL of its bills. Note: The government still will have inflows, they will just exceed the outflows.
Comment: That would be true if the government actually shut down. 83% is still operating http://washingtonexaminer.com/wheres-sense-of-crisis-in-a-17-government-shutdown/article/2536862
Comment: @CHAD - I dont understand how that affects the statement I made. If they are spending at any rate lower then 100% of normal, wouldn't there be more cash on hand? (Assuming no tax policy change and inflows are constant (or consistent is probably a better word).
Comment: @Chad - Which part 'would' be true? They are still not spending 17% of what they normally would, and as far as I know Lew's (Sec of Treas) original deadline of Oct 17th was assuming that a Continuing Resolution would be passed. So why wouldn't there be less outflows?
Comment: the 83 percent figure is only accurate when considering the cost of government services that are shut down. In terms of employees, or other metrics, you're looking at a lot more of the government being shut down.
Comment: @JSB1109 - "the Treasury may in fact have more cash on hand then it otherwise would,"
Comment: @avi actually the answer is looking at the cost of being shut down or rather the potential savings of being shut down.  So it is the right number to look at
Comment: It is, I just think it's more accurate to say that we're currently paying 83% as much as normal to run the government than it is to say that only 17% is shut down (or that 83% is still operating).


What is an extreme deep field image (XDF) and how is it captured?

Question: NASA recently took this Extreme Deep Field image (XDF) that is the area of only small fraction of the dia of moon and contains 5,500 galaxies. Nasa says this was capture by extreme long exposures so it can capture the smallest of galaxies. My question by increasing exposure times how can we know this is the deep space image because a galaxy might be right next to us but really really small and it would only show in these deep space image. Is there any other technology uses to determine this picture really captures galaxies that are 13.2 billion years old. How do we know this is really the deep space? Also can someone through light on some technicalities like the earth is moving and since we are focusing on really really small are, that rotation will cause blurs. If we take extreme long exposure it will make the easily visible stars extremely bright so it will again distort the picture. So my question is what id extreme deep field image and how is it captured over time?
Answer: The main problem with seeing very distant objects is that they're very dim. So little light reaches us from them that we have to record data for days and days to make them distinguishable from the background noise. This is what has been done in the XDF.
It's not commonly appreciated just how many galaxies there are in the visible universe. The number of stars in a big galaxy like the Milky Way is a few hundred billion. The exact figure depends on how many really dim stars you count. This is about the same as the number of large galaxies in the observable universe, and if you count small galaxies as well the figure is several trillion. Again the exact figure depends on how many dwarf galaxies you count.
The point is that if you look at any patch of sky you'll have more galaxies in the field of view than stars from the Milky Way, and it's not hard to find a patch of sky where there are no stars from the Milky Way - just galaxies. This is what the XDF did.
The distant galaxies in the XDF are too faint to measure a precise red shift, but the XDF measures the light over a range of wavelengths so it can get a measure of the galaxy's colour. This gives us an approximate red shift, and from this the distance can be calculated. You might object that galaxies may contain stars of different colours, but the red shifts are much greater than the range of colours within galaxies. In fact we can't see any more distant galaxies because their light has shifted too far into the infra-red for Hubble to see it. The Extremely Extreme Deep Field study will have to wait for the James Webb telescope to be launched.
You ask about focussing and the movement of the Earth, but the Hubble telescope is designed to compensate for this. It can also measure angles to stars with exquisite accuracy, so it's no problem to take pictures from ten years ago and combine them with pictures taken yesterday. Well, I say "no problem", I suspect the Hubble team would say it was a great deal of work! The point is it can be done.
I feel like this answer is a bit unfocussed, but then so was your question. Maybe this will help you refine your question to make it a bit more specific.
Answer: The adjective "deep" primarily means "a high resolution". The telescope just focused on a particular small region of the sky and took the sharpest picture it could.
There are no stars (from the Milky Way) in the XDF (or almost no stars, I am not sure) so the objects are bound to be far. In HDF, the "ordinary" Hubble Deep Field, one may find galaxies whose age is about 70% of the age of those in the XDF.
In all cases, the actual age of the objects is determined from the red shift – the multiplicative decrease by the well-known spectral lines. In HDF, they could find galaxies with red shift up to 6. I don't know the exact value for the XDF but it's larger than 6, perhaps up to 10 or so.
Using the Big Bang equations, the red shift may be translated to the distance and the age. (I will assume that the OP doesn't want to discuss conspiracy theories claiming that the huge red shifts mentioned above are due to something else than the cosmological expansion of the Universe.)
Comment: Lubos. Looking at it. It seems like some stars from our galaxy are there. There are smallish objects with the typical cross artefact of bright objects. Maybe they are very bight small close galaxies? Do you know what they are?


Which years/chapters of the manga is based the Gintama anime series?

Question: AFAIK, the Gintama manga series is been done for 15 years, when there is only 4 years of anime (though many of those manga volumes were made after the anime series, so it's impossible the anime is based on them). Which years/chapters of the manga is based the Gintama anime series?
Answer: My apologies, after being sought out I believe I didn't answer or read your question to the fullest.
You asked if any of the managa for Gintama was based on the anime. As I had to re-read your question, the answer to your question is none of it as far as I have read. You said the anime has been done for 15 years is false, the anime(assume your taking about the first to third season of said anime) started in 2006 then ended in 2009.
The manga that show is based on only came out about two years prior in it's initial Japanese release. The manga to anime followed this trend for awhile, with some arcs being dropped or switched out.
More episodes of the anime have came out in recent years with Gintama. Shirogane no Tamashii-hen having aired in January.
So re-state what i am trying to say in less words.
1. the anime has not been done for 15 years, it has continued with the latest airing of a new anime being in January.
2. the anime and manga have taken a break or two over the years due to various factors (artist health being one of them.)
3. None of the manga has been based on the anime, considering the manga chapter the anime is based on dropped two years prior to the anime episode being released.
Comment: I don't beleive Yorozuyasoul has been updated in years.  If it's just a list of what manga chapters correspond to which anime episodes, the Gintama Wikia is more up to date.
Comment: @kuwaly you are correct, I should have answered the question more fully.
Comment: @Gorp, you are also correct, the wikia is more up to date but I rushed to see this question answered and that is what I found within a few mins of googling. I will update this answer.
Answer: (Note that there was originally a typo in the first sentence of the question, where the asker had said "anime" when they meant "manga".)
The Gintama manga has indeed been ongoing for about 15 years (as of 2018) since it first started publishing in Shounen Jump on December 8, 2003.
The Gintama MyAnimeList page does show that it only aired for 4 years, from April 4, 2006 to March 25, 2010. However, more Gintama episodes aired afterwards. The anime's animation studio has put the anime on hiatus several times over the years to give the manga time to get ahead. Whenever the anime resumes, it gets catalogued as a new series on MAL. (Look in the Sequel links under the Related Anime section.) Relevant excerpt from the r/Gintama FAQ:

Why are there so many series (and why do they take up most of the top 10 in MyAnimeList)?
The reason why there are so many series is because the Sunrise Studio decided to take breaks with the anime. The breaks last from a few months to a few years. They did this to allow the manga to catch up so they didn't have to make a lot of filler or ruin the pacing. This is why Gintama is split up on MyAnimeList. Each series has its own separate name, but it is all connected. Think of it like the difference between Naruto and Naruto: Shippuden. Except without time-skip.

Though it should be noted that the first arc to air after the first anime hiatus was the Timeskip Arc...
You can see from the Wikipedia list of Gintama episodes that after each hiatus, the series was given a slightly different title to distinguish the new episodes from previous productions.

Gintama: ep 1-201 (April 4, 2006 to March 25, 2010)
Gintama': ep 202-252 (April 4, 2011 to March 26, 2012)
Gintama' Enchousen: ep 253-265 (October 4, 2012 to March 28, 2013)
Gintama°: ep 266-316 (April 8, 2015 to March 30, 2016)
Gintama.: ep 317-328 (January 8, 2017 to March 26, 2017)
Gintama. Porori-hen: ep 329-341 (October 1, 2017 to December 24, 2017)
Gintama. Shirogane no Tamashii-hen: ep 342-353 (January 7, 2018 to March 25, 2018)
Gintama.: Shirogane no Tamashii-hen - Kouhan-sen: ep 354-367 (July 8, 2018 to October 7, 2018)

(See also: "Why do anime series change titles so often?")
To clarify: The anime episodes are adapted from the manga chapters. The manga is the source material. That said, your question about which manga chapters the first anime series is based off of is a bit complicated to answer, because the anime doesn't adapt the manga chapters in the exact same order, so there is a lot of jumping around. However, chapters and episodes more or less move in the same direction in the long run, so to get a good rough idea of the chapter range, you can look at the latest chapter adapted by the latest episode.
As Gorp pointed out, Yorozuya Soul does have a nice mapping from episodes to chapters, although it's very out of date. (Note that in Gintama, chapters are referred to as "Lessons".) You can see from the Yorozuya Soul table that the latest manga chapter adapted by the first anime series (i.e. first 201 episodes) is chapter 292 (from volume 34).
Incidentally, Gintama volume 33, which contains chapters 283-291, was published on April 2, 2010.  (See the volume list.) Compare this to when episode 201 first aired, which was on March 25, 2010. So at this point, the anime had more or less caught up to the manga. So you can see why the studio would have wanted to take a hiatus at this point.
Some helpful resources with episode-chapter mappings:

Episode pages on the Gintama wikia (for example, episode 3) generally indicate the corresponding chapter or chapters in the infobox.
The Gintama wikia also has a series of pages that list the mappings from arc episodes to chapters: https://gintama.wikia.com/wiki/Gintama_Episode_List/Year_2006
The Japanese Wikipedia also has a nice table that lists the anime episodes and the corresponding manga chapters: https://ja.wikipedia.org/wiki/銀魂_(アニメ)#各話リスト


Where would a "Magic gland" go for full-body saturation of magic?

Question: If there were some organ, akin to the liver or a gland (I'm blanking on organ functions right now), that produces magical energy to project through the body, its various vessels, and directly out of the body, where would the most efficient location for it be? And where would it be if it were only to affect other organs (like forcibly activating melatonin, melanin, or adrenaline)?
Comment: Many people know about the vasculary (blood) system and vessels, but relatively few know about the [lymphatic system](https://en.wikipedia.org/wiki/Lymphatic_system) that carries lymph in lymphatic vessels throughout the body. The organs associated with the lymphatic system are the tonsils, thymus, spleen and (throughout the body) lymphatic nodes. Someone else could develop that into a magic gland and magic-carrying system.
Answer: These answers depend greatly on the way the vessels are connected.  If it needs to operate at chemical speeds, it might be able to simply hook into the bloodstream and have that do its thing (this is how our adrenals work).  If it needs to operate faster, it might choose locations which are connected in more of a neural approach.  Perhaps for fun, such an organ might be snaked along the spinal chord.
If Eastern style magic is useful in your world, consider having it very close to the center of gravity of the body.  Many Eastern groups believe there is an "energy center" there, such as the Dantian of many Chinese martial arts.  There are many such "energy center" concepts such as the Chakra used in many Indian religions and practices.
I'd also consider looking into what it connects to.  In yoga, for instance, everything is associated with the breath, so a magic system with elements borrowed from yoga would wish to make the organ related to breath.
And finally, many consider the heart to be an organ with the behaviors you mention.  It all goes to show just how much freedom you have to make such attachments, and make them work.
Comment: Yep, a single one connected to the bloodstream or a system of them also connected to the blood stream, but either case activated my the nervous system rather than chemical signaling. To get out of the body just get it out through the lungs, same as carbon dioxide or alcohol byproducts.
Answer: I would consider making the skin the magic gland. (The skin is technically speaking, one large organ). Since the skin is the boundary between the outside world and the inside of your body, it make sense to make the skin the organ, as it would allow the easiest "exposure" to manipulating the environment.
And since the skin wraps around pretty much the entire human body, it would have quick access to any inner sections of the body where we needed to project magic. If we need to directly apply magic to certain organs, the skin area closest to that organ would be able to activate, giving the lowest average magic application time.
Comment: Reminds me of the race of *Patryn* from the *Death Gate cycle* by Weis & Hickman. They had magical sigils or tattoos on their skin. Damage to the skin meant their magical integrity was compromised, at least temporarily.
Comment: Bonus points: better neural mapping for easier control
Answer: You can consider the mitochondrial potential.  They are the energy converters.  It has its own genome. They co-exist vitally with each cell and concentrations can vary widely, with some organs containing more than others.  I'd like to think that magical potential could reside within these mysterious motors.
Comment: Or each cell has a second mitochondria type organelle that powers magic rather than cell functions. But then you've just got midichlorians.
Answer: It's magic—why can't it go anywhere it wants?
The body has a variety of distribution networks already: the nervous system, the circulatory system, the lymphatic system.  Depending on how you envision your magic to work, you can place the organ centrally in any of these systems (e.g. heart or lungs for circulatory system, maybe basal ganglia for nervous system, thymus for lymphatic system (it's where immune cells that might attack the body are selected out)).  The pineal gland has interesting historical connotations.
But you can also postulate your own additional distribution system for magical power, arranged in whatever way makes sense for your idea of magic.  Chinese medicine postulates a system of "meridians" of just this sort.  You could pick somewhere where there seem an interesting convergence of meridian lines, for example.
Answer: The pineal gland already has mystical connections and has been used for this purpose.  You ought to play off that, along with the existing mythology of the "third/inner eye".
Answer: The best energy transfer system in the body for Magic would be The peripheral nervous system (PNS), the part of the nervous system that consists of the nerves and ganglia on the outside of the brain and spinal cord. This electrically based system is bi-directional, allowing you to sense magic as well as transmit it, and can allow for Reflex reactions. PNS reflexes can happen without active though, as the impulses don't even have to travel all the way to the brain in order to react.
So the Magic Gland should simply be part of the Spinal Cord.
Comment: While the transmission system could be through the PNS, you still have to address where the gland itself goes.
Comment: @HDE226868 It should go in/attached to the spinal cord. Like be part of the lining in the spine or something.
Answer: The endocrine glands affect most parts of the body, and as you can see from this Wikipedia image, they're all at or near the body's center line.
https://en.wikipedia.org/wiki/Endocrine_gland

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct.
Answer: It's magic. If it's stored then it has to be some sort of substance, but being magic it's not made of matter. My 2 cents, have a sort of aura. The aura being a real substance with most of it being subdermal and escaping through skin pores but have some of it being an outside aura that clings to the body. Perhaps the outer aura absorbs sunlight or some ambient magic just flowing around or perhaps magic is directed from the aura and the subdermal storage is for replenishing the aura. Perhaps mitochondria are the source and some of their waste heat is absorbed by the aura.
Biophotons is just infrared light from body heat. In that way people really do have an aura, it's just not magic. People also have terrahertz radiation and it's something that technology still struggles with making use of, though we are getting there.
To be clear if it's subdermal then the gland is in the skin, but under the protective layer of the skin.
Hope this helps. I'm curious to know what idea you'll decide to implement in your world.


Why do player start with fighting for the corners in go?

Question: I saw that in most go games the opponents started by placing chips 3 vertices away from the corners. Both players started fighting for the centre only after half of the game had passed. Is there any particular reasoning for this?
Answer: Common starting practices are to open by placing stones on a Hoshi (4-4 point), or close to it, in order to "claim" that corner. As the players are trying to secure as much area as they can, it makes sense to start out in a place that is easily defended, and that is something that's true for corners more than for any other location on the board at the start of the game.
Taking control of the center is much easier if the player has a solid base or even a number of solitary stones already placed, which obviously isn't the case at the start of the game. Furthermore, by trying to gain control of the center, your opponent would likely take all or most of the corners for themselves, which will eventually result in having to defend the center against all flanks.
In a real game, of course none of this will be this clearly separated, but those are the essentials it comes down to. Generally, you're not looking to immediately engage with your opponent, but rather to define areas of advantage for yourself first.
Because this question, just like most questions about Go, pose a larger complexity than would be feasible to go into here, I'll leave it at that and provide a few links that are likely to be reachable in the future to read further:

First moves
Open in the corner
Why don't we open at tengen

It should be noted that this is true for 19x19 boards - on 9x9 boards, you will much more commonly see players starting out at the Tengen (center starpoint), or at the very least try to compete for it much earlier on, simply because there isn't as much area to gain in the corners by comparison, and approaching the same strategy as on a 19x19 board would have you run into your opponent much faster than you'd like.
Comment: I would restate as "*Generally, you're not looking to immediately engage with your opponent, **but rather to define areas of advantage for yourself first.***" I believe this more accurately reflects the correct conceptual approach for an *opening strategy*. Otherwise quite good.
Answer: Capturing territory around the edges of the board is simpler and quicker, because the edge forms a boundary which does not have to be constructed with stones, and which can not be attacked from "outside".
Once a player has a safe territory attached to the edge, it can be extended towards the center of the board.
It is also relevant that a border just three stones wide around the entire edge of the board contains more than half the total board area. Of course a real game situation will be more complex than that simple piece of mathematics, but the general principle it demonstrates is important.
Answer: Because you need less stones in the corner to live than in the center. And by extension, you can surround more area in the corner with the same number of stones.
Some figures to visualize this:
Live group in the corner, 6 stones:
<code>+------
|.xx..
|x.x..
|xx...
|....
</code>
Live group in the middle, 10 stones:
<code>......
.xx...
.x.x..
.xx.x.
..xxx.
......
</code>
(See Smallest Group with Two Eyes on Sensei's Library.)
Those same 10 stones placed in the corner could cover much more points than they can in the middle:
<code>+-------
|....x.
|.x..x.
|....x.
|....x.
|xxxxx.
|......
</code>
Answer: It is plain and simple that it is much easier and more efficient to make life groups and territory in the corners than along the edges or in the centre. In the corner, you need two outer walls, along the edge three, and in the center four to enclose your territory.
And Go is about enclosing territory, after all.


Doxygen vs Javadoc

Question: I just realized from an article in CACM that Doxygen works with Java (and several other languages) too. But Java has already the Javadoc tool. Can someone explain what are the pros and cons of either approach? Are they mutually exclusive? Is there a Maven plugin for Doxygen?
Answer: Doxygen has a number of features that JavaDoc does not offer, e.g. the class diagrams for the hierarchies and the cooperation context, more summary pages, optional source-code browsing (cross-linked with the documentation), additional tag support such as @todo on a separate page and it can generate output in TeX and PDF format.It also allows a lot of visual customization.
Since Doxygen supports the standard JavaDoc tags you can run Doxygen on any source code with JavaDoc comments on it. It often can even make sense to run on source code without JavaDoc since the diagrams and source code browsing can help understanding code even without the documentation. And since the JavaDoc tool ignores unknown tags you can even use additional Doxygen tags without breaking JavaDoc generation.
Having said all this I must admit that I haven't used Doxygen for a long time. I tend to rely heavily on my IDE nowadays to provide the same visualization and I usually don't read JavaDoc as HTML pages but import the source files into my IDE so it can generate JavaDoc flyouts and I can jump to the definitions. That's even more powerful than what Doxygen has to offer. If you want to have documentation outside the IDE and are happy to run non-Java tooling then Doxygen is worth a try since it doesn't require any change to your Java code.
Comment: With maven, you can aggregate javadocs and cross link them using the site plugin. In addition, there is a UML doclet that can be used which generates the class diagrams you're referring too. Doxygen can be very slow for large projects and requires a number of hoops to jump through to make it quicker
Comment: Is Doxygen compatible with `{@link #myMethod(MyArgType)}` and `{@link #myMethod}` syntax?
Answer: I'd only use Doxygen with Java if you're new to Java and you've used Doxygen before, reducing the learning curve you'd experience with javadoc.  If you haven't used Doxygen before, I'd stick with javadoc, since it was specifically designed with Java in mind.  If you don't know either one, and you work in C++ (or other supported languages) as much as you do Java, Doxygen is a good choice, as you'll be able to use it for both languages.
Both tools are easy to use, with a similar feature set.  Both have plugins (or are pre-built in) for NetBeans and Eclipse making it even faster to generate doc.  There is a lot of overlap in the comment style used by each, but they're not exactly the same, so it would be difficult to mix them together (you'd have to know the details of both, leaving out any features that are specific to one or the other).  I've never used it, but there does seem to be a Maven plugin for Doxygen.
Comment: Here's a link to the Doxygen Maven plugin: http://khmarbaise.github.io/doxygen-maven-plugin/
Answer: I like the fact that with Doxygen, you can get class diagrams displayed on the same page as the documentation.  Also, I like the fact that it links you directly to the source code, if needed.  I am not aware if javadoc has these features though.
Comment: Yes javadoc can have class diagram too: http://www.yworks.com/en/products_ydoc.htm (not free though... I try to remember of another similar tool freeware)
Comment: http://java.dzone.com/articles/reverse-engineer-source-code-u
Comment: You can use the free APIViz doclet (http://code.google.com/p/apiviz/) to generate class diagrams in javadoc.
Comment: http://www.umlgraph.org/ maven graphviz plugin
Answer: One big advantage of JavaDocs is that they just work. Everything needed to build and view them is included in the JDK that you already need to have installed for compiling your programs.
Doxygen, on the other hand can be a pain to set up and get working correctly. but if it is set up correctly it should be able to generate PDFs, RTFs, and DocBooks, as well as HTML. The HTML is not organized as well by default as JavaDocs since the index.html brings up a blank page by default. Also, inline classes and static members may need special flags to be included in documentation, and if you want to generate a PDF you may have to deal with hassles of your distribution of Linux not having the needed pdflatex command (e.g. Ubuntu/Mint have had problems recently) so if you just apt-get install it and run you may get a screen full of errors even with a simple program. Compared to the ease of getting javadoc automatically when you install the API, Doxygen setup can be a miserable experience. Once you overcome the hurdles, it should be more flexible in dealing with projects involving more than just java, though.
Comment: I'm not sure Doxygen is such a pain to setup. One Doxyfile that can even be created using a wizard and off you go. But my comment comes almost 9 years later so the distribution may have changed.

Doxygen vs Javadoc


How can I prevent the screen from going black in vnc when inactive?

Question: When I'm using VNC, the screen goes black after an inactivity for around 2 seconds. If I move the mouse or press a key the screen goes back however this is very annoying.
I have KDE 4.10 on both systems, I'm tunneling the VNC through the SSH connection (ssh -R5900:localhost:5900 myhost) from the server to my local computer.
I'm using x11vnc as a server and Tight VNC as a client.
I've tried different vnc clients (vinagre, real vnc, xvnc4viewer) but the issue remains.
Also, I've tried different settings to x11vnc server (-sb 0 -nonap -noxdamage etc) but nothing works for me.
There is a thread on kubuntuforums with the same issue, but doesn't seem to be resolved.
Do any of you have some idea what can be causing this behavior?
Answer: on the server issue the following command:
xset dpms force on


Why didn't Helen close her eyes and keep them closed?

Question: In Incredibles 2, after it was revealed that the pizza delivery guy was controlled by goggles and Evelyn reveals her plans to Helen, the latter being tied up in a chair, why didn't Helen close her eyes and keep them closed? That would have kept her from being re-hypnotized.
Answer: The hypnosis happens fairly quickly while Helen and Evelyn are talking (about a second in movie time) and with Evelyn being a small distance away with a small remote to trigger the hypnosis, so it's possible Helen didn't have the time to react properly (especially as she was being slowed / heavily affected by the ice-cold area around).

Of course, it's a movie for kids, so instead of a long drawn-out scene with Helen keeping her eyes closed, suffering some torture to make her open her eyes OR Evelyn just waiting until her eyes opened (eg after Helen slept and woke up), it just happened straight away.


Precious minerals in Terraria

Question: I've found some Emerald, Diamond and Amethyst but haven't seen what I can do with it.  I'm still in the beginning stages, trying to outfit myself in gold armor and weapons.  I was curious if I should sell these minerals or keep them around for crafting purposes.
Comment: If you don't need the money, you might want to hold on to them anyway. They'll likely be good for *something* at some point in the future. If you're doing item trading, many people also accept them as payment based on this assumption.
Comment: Thanks guys!  I think have 10 of something so I'll go ahead and sell the leftovers.
Comment: Playing solo on this character so no trading.  I could use the money, that miner's hat looks so handy!
Comment: Just a side note, if you even encounter a new item and want to know what recipes it can be used in, just give it to the guide! He'll give you a list of every single item in the game that has that item in its crafting components.
Answer: You can use ten of the same gemstone, plus 20 Meteorite Bars, to craft a phaseblade. All phaseblades are identical except for color, which is based on the color of the gemstone. You only need ten total gemstones, all of one type. You do not need ten of each.
As of 1.05, they have other uses! Six to ten each of two gemstones are required to craft Jungle Armor set pieces. You will need ten emeralds and sapphires, eight amethysts and topaz, and six rubies and diamonds. (for a total of 48 gemstones.) Additionally, rubies are used to create the Robe and Gold Crown, while topaz are used to create the Sandgun. (Source: http://wiki.terrariaonline.com/)
As of 1.1, each of the gemstones can be combined with 3 torches to produce 3 colored torches (shows off Terraria's new lighting engine!).
As of 1.2, each of the gemstones has an associated ore that it can be crafted with to create a "___ Rod" item, which is a rod made out of 15 of your gemstones and 10 bars of a particular ore.  The Diamond and Ruby rods are First-and-second best, and use Platinum and Gold bars respectively.
All gemstones can now also be used to craft new grappling hooks that don't require a Hook to create, making them ideal for new characters. The Ruby and Diamond hooks also have a longer reach than the Ivy Whip.
In addition, these gems can be used to create Large Gems for the Capture-The-Flag game, so it would be wise to hold onto some in case you ever wish to host said game for some of your friends.
Comment: +1 for items hoarding, because who knows what future will bring
Comment: jprete - you're welcome! Though to be completely honest, I thought I was edited my own answer when I did it. -_-;;
Comment: I want glowing colored stone blocks. With it, you can build your Terraria art structures that lights up at night without the need for torches.
Comment: @Raven Dreamer: Thanks for updating the answer to reflect 1.1.
Answer: As of patch 1.04, Rubies are used in two non-phaseblade recipes -- the "Robes" and the "Golden Crown" vanity items.
The robes requires 3 rubies and 30 silk, while the Crown requires 1 ruby and 30 gold bars.
Robes on official wiki
Golden Crown on official wiki
As of patch 1.05, Gemstones are used to create the pieces of Jungle Armor as well.
You'll need one of each to craft the whole set.
Jungle Armor on official wiki
5 Topaz can be used to make the Sandgun with Antlion mandibles and Illegal Gun Parts.
Sandgun on official wiki
Finally, as of 1.1, each of the gemstones can be crafted with 3 torches (no workbench, etc. required) to produce colored lights (same respective colors as the phaseblades).
Answer: The main thing that you can craft with them is the phaseblade, which takes 10 of one type (changes color), but other than that, sell sell sell.

Precious minerals in Terraria


Upgrade to HID lights in a Jeep Wrangler

Question: I would like to upgrade to HID lights in my 2008 Jeep Wrangler.  The stock lights aren't bright at all.  My question is, since this would be an aftermarket upgrade, what am I looking at here?  Is it as simple as swapping in new bulbs?  Are there other electronic modifications I would need to make?
Answer: Xenon headlights require different electronics to drive them, but they also need different reflectors and also a light leveling system to prevent blinding the drivers of other cars, because the HID lights are so much brighter than traditional lights.
If you look closely at a car with HID lights, with the lights shining on something in front of them, you will see that the lights basically cut off at a neat line along the top, where traditional lights illuminate up much higher.
If you know someone with HID lights, ask them to show you when they start up.  The ones in my car move up and down as they adjust to the load in the car, so that a load in the trunk won't cause the lights to shine higher than they're allowed to and blind oncoming traffic.
I had done some research for my old '94 300ZX that I wanted to see if I could retrofit.  The kit for them was $3,000 a pair, because of the leveling system and the electronics to drive them.
My solution?  I replaced it with a new car that had HID lights.  They are totally worth it, they are lovely lights and I find when I'm driving my other car without them I keep thinking "are the lights on?"
Another caveat: Some places are selling "cheap" HID light kits from Japanese models.  However, they can't be used in the US or other left-hand-drive places because the left hand lights shine up higher than the right lights, and they can't just be swapped around.  The lights for LHD cars are the opposite, where the right light shines higher.
Additional details are available in this related question: KIA Soul Aftermarket Headlights
Comment: 3k sounds way too high for a conversion kit. I'm not sure for the 300zx because i know parts can be a challenge for that model, but for most Hondas there are top of the line kits available for a small fraction of that price.  That's with appropriate assembly and a kit which is plug and play
Answer: My H.I.D. plug and play light upgrade cost me $350 (easy install) and is superior in every way compared to usual factory fit.They don't run hot and as every car I have owned has adjusting screws on headlight surround meeting legal requirements should not be a problem.
Makers of these kits usually advise starting engine before turning the headlights on.
Comment: Do you have a link for the kit? Or at least at manufacturer?
Answer: You have received some good answers here, but none appear to be specific to the Wrangler.
The Wrangler uses a standard 7" round headlight housing with H13 bulbs, and there are several HID kits that will work very well in these housings that will plug right into your stock wiring harness. The HID bulbs will fit right into the housing the same way as the standard H13 bulb. Since both sides use the same bulb, there's no problem swapping them left to right, but there's no point, as the bulbs are identical.
Similar to what mike stated above, once you've installed your new HID kit, you can re-aim the headlights, as there are adjustment screws to allow this.
One thing to note, in order to remove and replace the bulbs you have to remove the grille (simple enough, there are six plastic clips on the top to remove, then you can pull the grill right off) and remove the housings. There's no room behind them to access them otherwise.
As was already mentioned, HID bulbs do require a ballast, but a good kit will come with those ballasts pre-wired to plug into the standard H13 wiring and the bulb will be shaped to fit directly into the housing. You will have to firmly attach the ballast to the chassis, usually with a couple of screws. Since you'll have the grille off, You'll probably find a spot without too much trouble.


How do I generate an xPub using stellar SDK?

Question: How do I generate an xPub using stellar SDK ?
could anyone show me the format of a stellar extended public key ?
Answer: You can't generate xPub for Stellar keys according to SEP-0005. Stellar is using SLIP-0010 (as defined in SEP-0005). From "Master key generation" section:

ed25519 curve the private keys are no longer multipliers for the group generator; instead the hash of the private key is the multiplier. For this reason, our scheme for ed25519 does not support public key derivation and uses the produced hashes directly as private keys.

There are proposals for generating HD keys with a possibility to generate extended public keys for ed25519 like:

https://chain.com/docs/1.2/protocol/specifications/chainkd
https://cardanolaunch.com/assets/Ed25519_BIP.pdf

However these are not supported by Stellar.
Why Stellar selected SLIP-0010 over other solutions?
SLIP-0010 is supported in hardware wallets like Ledger or Trezor. We wanted a solution that is compatible with them.
Comment: Hi, thanks for this answer! However, both links in this post are dead, is anyone able to update them to new locations?
Answer: I think there is no API to generate it from Stellar SDK
This link help you to generate xPub
https://iancoleman.io/bip39/?#english
Comment: That tool doesnt have stellar !
Comment: I think stellar does not support xPub


When should we use SWIFT versus FIX?

Question: I've read documents that claim that SWIFT and FIX are not competing protocols for financial transactions and messaging. And yet, I have not come across a clear articulation of when to use SWIFT versus FIX. For example, I know that FIX can be used for most trading activities, e.g. getting a quote, placing an order, canceling an order, getting settlement instructions, managing positions, etc. And I was under the impression that SWIFT is primary for accomplishing electronic wire transfers of money between financial institutions, e.g. as part of the trade settlement process. However, now I'm told that SWIFT can also be used to handle rolls and closeouts. Am I right in thinking that there's a significant overlap in terms of the domains covered by the two protocols? Would anyone care to take a crack at clarifying?
Comment: These is nice work of a quant friend, from London, http://fix8.org
Answer: SWIFT is actually not a standard per se; rather, it's an organization that operates a proprietary exchange network that utilizes a set of ISO messaging standards.
FIX is a non-proprietary set of messaging standards with no underlying network specified.
There is certainly overlap between the two, and there has been work to co-align these standards. I would say the choice between them would be made more on the transport requirements (e.g. SWIFT for a centralized guaranteed delivery) and on the fringes where they don't overlap.
A couple salient threads from the FIX website:

http://www.fixprotocol.org/discuss/read/46f5a06f
http://www.fixprotocol.org/discuss/read/53a3fa9b
Answer: FIX is frequently used for order entry traffic (new order, amend order, cancel order) and occasionally used for delivering market data when latency and performance are not critical.  (FIX/FAST is quite different, that is an encoding that CME and others use to compress price feed information.)
If you are entering orders (either to a broker or directly to an exchange), FIX is a good choice, and is often your only choice.
Answer: SWIFT messages are expensive where as FIX is totally free.
Comment: That's not a fair comparison as SWIFT is an organisation and FIX is a message format.
Answer: SWIFT are proprietary and easy to use for all the firms as 98%+ world wide coverage they have.

When should we use SWIFT versus FIX?


Did Valmiki ever meet Lord Rama prior to the Ashwamedha?

Question: I came across a question on this site about Veda Vyasa, the author of Mahabharat, meeting Lord Krishna and I was wondering if similarly Valmiki also met Lord Rama sometime. They have met at the time of the Ashwamedha Yagna when Luv and Kush defeated Lord Rama's army but I want to know if they ever met before in life?
Comment: @hanugm May be I think OP got the idea from similar sites like this one .The author exaggerated many things in this article. https://sites.google.com/site/grandfatherstales/part-1 ,  I think these  stories are intended for small kids who just needs to introduce names like Rama and Valmiki , i think .
Comment: *They have met at the time of the Ashwamedha Yagna when Luv and Kush defeated Lord Rama's army*            from where/ which text you got this?
Comment: @SwiftPushkar Yeah.
Answer: In Ayodhya Kanda it was mentioned that before constructing their hermitage on Chitrakuta mountain, Sri Rama, Sita and Lakshmana met Sage Valmiki.

इति सीता च रामश्च लक्ष्मणश्च कृताञ्जलिः |
  अभिगम्याश्रमम् सर्वे वाल्मीकि मभिवादयन् || २-५६-१६
After deciding thus Seetha, Rama and Lakshmana all with joined palms approached the hermitage and offered salutation to the sage Valmiki.
तान्महर्षिः प्रमुदितः पूजयामास धर्मवित् |
  आस्यतामिति चोवाच स्वागतम् तु निवेद्य च || २-५६-१७
The great sage Valmiki, who knew what is right, full of delight, treated them with honour, offered cordial welcome and requested them to sit.

&&&&&&&&
Ramayana was silent as to whether the poet Valmiki, who wrote Ramayana, and the Sage Valmiki that Sri Rama met at Chitrakuta mountain are one and the same.
Comment: Those verses seem out of place in that chapter and are clearly interpolations. Also, not present in [Bibek Debroy's translation](https://i.stack.imgur.com/oFRyZ.png) based on the critical edition.
Comment: Oh wo this is interesting! Thanks for sharing