What's the best way of replacing a plug or switch in a house with aluminum wiring?

Question: My house has aluminum wiring, which from what I understand isn't recommended any more. How do I replace a plug or switch since the new unit only takes copper wiring?
Comment: Just because there is aluminum wire dosent mean you have a fire hazard. Properly installed with aluminum compatible devices have been in use for decades. Most homes main service feeder currently being installed today is still aluminum. Almost all main lugs on panels are aluminum so because there is aluminum dosent mean there is a fire hazard. When remodeling homes with aluminum wire I always use a anti oxide compound like noalox, or deox two main ones I use but there are many brands that work. the other thing is torquing the screws properly. Al wire is just as safe as back stabs with copper.
Comment: You've got a fire hazard!  The aluminum oxidizes over time, increasing the resistance of the connections.  Resistance x current = power (heat) lost at the connection.  The connection heats up and cools down, slowly working its way loose and further degrading the connection.  At our old place we had arcing inside the main breaker panel at the connections to the aluminum feeder wires due to this!
Comment: Wow, I've never heard of aluminium wire being used in a house before.  http://en.wikipedia.org/wiki/Aluminum_wire
Answer: There are two ways to do it:

Use CO/ALR switches/receptacles: these are specifically designed for aluminum wire. They have "CO/ALR" stamped on them somewhere. When you connect the wire, use a paste like Noalox (box stores sell it).
Use a pigtail connection: Sometimes it is not possible to find CO/ALR switches with the function or style you need. You can use a copper wire to connect to the switch itself as usual, and then a #63 wire connector to connect the copper wire to the aluminum one. Here is a picture of a 3-way dimmer switch I installed using this method:

(apologies for fuzzy picture)
Note that you do the same thing with switches that have wires coming out of them already (like most dimmer switches do) or any other fixtures.

To quote from the ESA (Ontario Electrical Safety Authority)'s Notice on Aluminum wiring in residential installations:

Even though not required by the Code, it is
  recommended that bare ends of solid aluminum conductors be coated with approved joint compound.
...

The Ontario Electrical Safety Code permits the installation of aluminum wiring.
Adequate precautions shall be given to the terminations and splicing of aluminum conductors;
Aluminum wiring itself is safe if proper connections and terminations are made, without damaging
  the wire and devices approved for use with aluminum wire are employed.
Aluminum wiring is widely used today for larger commercial and industrial feeders. Electrical distribution companies use it widely throughout their distribution systems including the supply service cable to most residences; in fact it may still be used today for interior wiring systems in
  residential homes as well as other structures.

...
Aluminum wiring itself is safe and if proper connections and terminations are made without damaging the wire and using approved materials installed in accordance with the Ontario Electrical Safety Code and the manufacturer's instructions, there should be no problems with the aluminum wiring installation.

In either case:

Connect with #63 wire connectors.
Use the anti-oxidant paste on the wire and any other connections involving aluminum (apply to the wires before you screw on the connector).
Use a wire brush to remove any oxidation before applying paste and making the connection
Comment: According to the CPSC (Consumer Product Safety Commission), "CO/ALR devices must be considered, at best, an incomplete repair" that's only intended "as an emergency, temporary repair of a failed aluminum termination." Though less detailed, the [answer below](http://diy.stackexchange.com/a/7372/13142) by @Jerr seems to be the safest method for dealing with aluminum wiring. See http://www.cpsc.gov//PageFiles/118856/516.pdf for more information.
Comment: Use the oxidation inhibiting paste, but also wire-brush the exposed wires before applying the paste.  ;-)
Comment: @kevinmicke I find it hard to take the CPSC document too seriously when it doesn't even mention anti-oxidant paste at all. Contrast that to what the ESA says, which I added to my answer.
Answer: Here's what I did in my house, based on internet research and asking my Dad, a construction superintendent.

Buy some wire nuts made for multiple types of wire and some anti-corrosion compound (usually available in the same area of the hardware store).
Take some copper wire and twist it together with the aluminum wire.
Put the compound on the wire and some inside the wire nut.
Twist the wire nut onto the wire twist you made.
Use the new copper end to connect to the new plug/switch.
Comment: Very important safety note for the above: I believe you need to put the corrosion compound on BEFORE you twist the wires together. This prevents bimetallic corrosion between the two different types of wire, which would lead to higher resistance and a fire. Just smearing it on after you've already joined the wires is not enough.
Comment: If you need to connect copper to aluminum, do not directly twist copper with aluminum. The two will eat at each other, and resistance and heat will increase. The only way to splice copper to aluminum safely is using a device listed for that use. Others here mentioned a wire nut that you can safely use instead.
Comment: While that will prevent corrosion, won't you still get the separation caused from the heat generated between the copper and aluminum expanding?
Comment: You should also use a wire brush on the exposed aluminum before applying the rust (oxidation) inhibiting paste.
Answer: I am a licensed electrician in Connecticut. My own condo has aluminum wiring, I highly recommend the alum.con connectors because they are homeowner friendly.  Two methods are presented:

a special torque screwdriver (recommended)
a set of specific instructions for the number of turns on the copper side/aluminum side.

These connectors are quickly becoming accepted by major insurance companies. Their downside is price: approximately $2.00 each, and figure three per outlet if you choose to do the grounds as well.
Also they are a bit larger than standard wire nuts adding a bit more difficulty for wire and device room in a existing device box.  They appear to be code compliant in most cases for cubic inch capacity.
I have installed them in my home and neighbors.  The biggest issue with aluminum wiring arc issues are exterior walls that are poorly insulated and major temperature changes occur over the years exaggerating the expansion/contraction issues.  Hope this helps.
Do not use the Ideal purple wire nuts; I've seen too many melt downs; it's a bad product.
Answer: I discovered I have the same issue here. My research has found that aluminum wiring is UNSAFE, and you need to be very careful about what you do. The two options are:

Replace the wiring. This is not something that would be safe to do on your own (you really should get a licensed contractor), and looks to cost several thousand dollars (like $8000+ for a 1600 sq ft home).
Use AlumiConn. This stuff is actually approved to be used for aluminum to copper connections (the other pigtails mentioned here are NOT), and you can get a free sample to try it out. There's another thing, called COPALUM, but it's not really something you can DIY. Wikipedia has some good information on this.

I'll update when I actually get my sample AlumiConn connector to see if it's a viable option. The safest option would be to get a licensed electrician to rewire the house with copper, since the aluminum connections are inherently dangerous (and you will probably find other issues, such as bad breakers, 3-wire 240V instead of 4-wire, and a poorly labeled breaker box like I did). I've had receptacles in my house spark and connections melt because of the aluminum, so please take this seriously.
Edit 1: There's also more information about aluminum wiring from the CPSC (PDF) (Consumer Product Safety Commission).
Comment: The main issue with the aluminum conductor is that aluminum expands more than copper when heated.  This can cuase loose connections which can lead to arcing at the point of connection.
Comment: "since the aluminum connections are inherently dangerous"  How so? Isn't the only danger when you mix them with copper or other non-approved components?
Comment: You still have the problem of oxidation. When the connection oxidizes, it increases resistance, which ultimately means heat. I'll update my post with a link to the CPSC document on aluminum wiring.
Comment: @Zach I know I'm coming along years later here, bu the Jerr is right. Aluminum rust (aluminum oxide) is an effective electrical insulator. It doesn't conduct electricity. So if even a straight aluminum to aluminum connection isn't protected from oxygen, it will oxidize and create resistance and heat, which can lead to a fire.
Answer: My parent's house has aluminum wiring. You can either search for CO-ALR switches and plugs which take aluminum wires or get the paste as you said and wire them together. The paste is important, otherwise the wires corrode and start rubbing/sparking .... bad mojo from there.
Comment: Also a good idea to wire-brush the exposed aluminum wire ends before applying the paste. Aluminum oxidizes very rapidly. In fact, if aluminum oxide didn't form an air-tight seal when it forms, you could almost watch an entire chunk of aluminum rust right in front of your eyes.
Comment: It's not an "either/or". You don't use CO-ALR receptacles *or* the paste.  You use both.  In other words, the paste is not a magic elixir that would let you splice aluminum wires direct to copper wires. There is no such thing.  Well there's a purple wire nut, but google that and you'll get a lot of pictures of wire-nut fires.
Answer: Just buy the ALR rated outlets and switches. You can pigtail but I don't like that as you now have 2 connections instead of one and you bend the wire more stuffing all that into the box. I have 35 yr old alum wiring. My wiring is in great shape. Replaced several outlets that needed to be replaced. They had the classic alumnimum connection issues. Connected properly there is no problem with aluminum wire. I remember when it came out the industry was publishing all sorts of propaganda to sell ALR as the next big thing. Popular mechanics did a big piece  saying we'd never use copper again. Now they are selling $50 "special" cold weld connectors. Its all a big friggin joke and a $ machine. A good connection will remain in place for decades no matter how many hot/cold cycles it goes thru. A bad connection may very well have problems.
Comment: You should probably talk about what a proper connection is.
Comment: Pigtailing in general is fine. In fact, it's preferable to connecting multiple wires to a device like a receptacle. Aluminum connections that aren't done right can start fires, and there's no getting around the fact that making a proper electrical connection with aluminum is more technical (and thus more prone to mistakes) than with copper.
Answer: /The aluminum to copper splice connector that I use is the AlumiConn 95104 which fits wire from #18 to #10.  Remember that aluminum wire is larger than copper for the same capacity current.  These connectors are available at Lowes for about $6.50 for a package of 2.
Answer: First,  fit an AFCI breaker on the circuit.
Then, fot CO/ALR receptacles and switches where you are concerned.  Tighten their connections with a torque screwdriver so the torque setting is correct. It matters.
Then, sleep well.
The keystone is the Arc Fault Circuit Interrupter breaker. I cannot see a way to feel safe without it.  You hear about melted receptacles and other problems, that is caused by arcing and that is what AFCI breakers trip on.  When an AFCI trips, that circuit has just started the arcing that would melt receptacles and start fires.  At that point, you move through the circuit, cleaning up all the wire ends and fitting CO/ALR devices and safe splices.
I don't trust any "magic" wire nuts which let you splice copper to aluminum.  Dissimilar metals cannot work in a wirenut.  What works is Alumiconns, as they are miniature versions of the lugs on your main panel, which work fine with both aluminum and copper.
Answer: To my knowledge, insulated 2-3 port splice connectors (such as Alumiconns or MAC Blocks) are the safest product on the market right now.  NSi Industries (Tork) makes something similar (their IPL series), but I'm not sure if they make really small ones like you need.
Answer: My niece has the same problem with whole house wired in aluminum.  The reason I know is she asked me to checkout a sparking receptacle in her game room. I ended up finding three receptacles burned to a crisp and needing repair.
After trying to find which direction to use for repairs on the internet, it seems like the alumiconn connector is my best choice (other than rewiring, or that crimp method that pros use).
Comment: Multiple burned up receptacles could also indicate that the installer did not use the correct torque on the terminals, possibly making the aluminum incompatibility problem even worse.  That matters so much they make you use torque screwdrivers today.


Is there a way to have Cycles skip rendering alpha?

Question: If I wanted to create an animation, each frame would have several seconds of rendering a completely transparent part, which adds up obviously. Is there a way to eliminate this waste of time?
Comment: @someonewithpc I believe it's 2.74+
Comment: A partial solution might be to make these black; in newer versions of Blender (2.73 if i recall), if the world background is black, it will be removed from the sampling tree making it faster. Try this and see if the render is any faster.
Comment: Fully black background does render slightly faster than a non black background, but transparency is still slightly faster than both. In my mind the only things that will control this issue is tile size and render frame size. Perhaps if your animated element doesn't move around the whole frame, you could render a cropped frame and composite it back into the shot in the right place later.
Answer: There is nothing specifically designed into Blender to tell it to ignore the transparent areas currently.
That being said, there are some things we can do to help speed up the render somewhat.

Transparent Background - Choose transparent in the Film section of the Render properties panel. This will render faster than a coloured background (whether full black or not)

Tile Size- Choose a smaller tile size than your current (this tip is mostly for CPU rendering as GPU rendering generally uses larger tiles). This will help the render times when the buckets are processing the edge of the foreground element.

Targeted Sampling - Use the Branched Path Tracing option in the Sampling section of the Render Properties panel. If you reduce the AA sample some what and raise the bounce samples (Diffuse, Glossy, etc.), you will reduce time spent on rendering the sky/transparent background.

Cropped Render - this option is a little more extreme, but if you    have an object that doesn't move much on screen, you can crop the    render to only include the portions of the screen it's in. You'd then    composite it together with the rest of the full frame renders.
Comment: I did a quick test, and you're right, rendering with transparency seems consistently faster (even if only by a few milliseconds), which surprised me. Any idea why this is?
Comment: I'm not sure why, but I would have thought it would be much faster, which it isn't. Cycles needs some sort of mask pre-processor to skip the alpha area completely.
Comment: The only thing it's doing is replacing the sky with alpha for the camera, it still needs to send rays to get reflections of the actual environment (I guess since the environment still influences the scene it can't be skipped in any meaningful fashion). As a matter of fact I can't see any reason for transparency to be faster at all..?
Answer: Full disclosure, the add-on I'm about to recommend is a paid for add-on created by me, but I think it does what you need as it was built partially for the very task of skipping transparent parts of an image.
If you were rendering a still image you could use the 'render border' feature of blender to skip areas outside of the chosen area. For animations you can use my add-on, the Animated Render Border (link to Blender Market product page for add-on). This updates the render border every frame so it always surrounds the selected object or group and works both in the viewport and the final render, allowing the skipping of transparent parts for all frames. It also has an adjustable margin to allow for a slight border around the object.
Here is a (choppy) gif showing it in action:
Comment: I'm specifically looking for a render layer border animator, is that a feature in your addon?
Comment: Ah, I see. It supports render layers if you are rendering them separately or if each of the render layers requires the same border (unlikely). Basically, the border can update in between renders but not inbetween different different parts of the render, e.g. render layers.


Can Appium automate the In App Purchase flow on iOS?

Question: Making an In-App Purchase (IAP) on iOS brings an Apple alert and puts the application into the background. If I use the Appium framework for automation, will I be able to interact with these prompts? Bonus if you could point me to an example of it. It was not immediately obvious to me that this was supported, though my understanding is that that UIAutomation framework might support this and that Appium calls into that framework. I'm in the process of evaluating frameworks.
Comment: your question is not clear to understand.
Comment: @sameerjoshi The IAP process involves system prompts that take you outside of your app, e.g. "Do you want to buy a widget for $0.99?" This makes automation a challenge if the automation software loses control once your app is in the background.
Answer: Appium have capabilities to auto accept or dismiss the alerts, you can use these capabilities to complete your flow, as per your requirements:
autoAcceptAlerts = true

capabilities.SetCapability("autoAcceptAlerts", true);

or
autoDismissAlerts = true

capabilities.SetCapability("autoDismissAlerts", true);

Furthermore, some of the older versions of Appium haven't worked with this solution, so you might want to try a small workaround with this:
driver.SwitchTo().Alert().Accept();

Note : If Auto accept/dismiss capabilities used, it will accept/dismiss all the alerts of the application automatically.
Answer: I have not actually implement this scenario @Ben. But as you said,

IAP process may take you out of the app. Most probably browser
In that cases its possible to automate it

I am confident because

I have automated successfully the scenario where my app also redirect user on browser.
I'll say it would be the power of Appium to have support for Web and mobile platform in a same & single test.

Please give a try and let us all know if any smarter ways or challenges you face.
Comment: On iOS In App Purchases do not take you to a web browser, but your app loses focuses and Apple produces dialogs. It may ask for a password, or it may ask if you approve the purchase. In our testing with UIAutomation we have not been able to consistently manage this situation. Perhaps you are thinking of sales of real world goods -- the case I am talking about is virtual goods, the kind you set up in iTuneConnect.


How can I copy all metadata, including color profiles, from one jpg to another?

Question: I tried exiftool -tagsFromFile but it seems to skip color profile exif.
Answer: Below is a note from EXIFTools documentation -
"1) Some tags (generally tags which may affect the appearance of the image) are considered "unsafe" to write, and are only copied if specified explicitly (ie. no wildcards). See the tag name documentation for more details about "unsafe" tags."
Also, see question 9b on this page: http://www.sno.phy.queensu.ca/~phil/exiftool/faq.html
In short, you may have to be explicit in your statement.
Answer: After a lot of trials and errors, I managed to do what you're asking by using the ExifToolGUI (http://u88.n24.queensu.ca/~bogdan/). I tried before with the command line ExifTool, but I just couldn't get the right parameters.
With the ExifToolGUI, you select the source image, go to the menu [Export/Import]-->[Copy metadata into JPG or TIF files...], select the destination image, check all checkboxes for the metadata you want to copy in the next dialog, et voila.
I had an image scanned from an EPSON scanner with an EPSON ICC profile which I wanted to copy on another image and it worked perfect.


What does it take to become a registered Animagus?

Question: So, I've wondered for some time, if you need a permit to be an Animagus in the Harry Potter universe, how do you learn to do it beforehand? Is there some class, or something? And as there's only seven registered Animagi (as per "Order of the Phoenix"), who would teach the course, and certify the person for that matter?
Comment: I think it's registered as in "Sex offender", not "Certificated". It's an innate talent, one can either do it or not.
Comment: Not to mention, how do the unregistered [Animagi](http://harrypotter.wikia.com/wiki/Animagus#Known_Animagi) learn how to do it?
Comment: I seem to remember coming across something about Animagi while browsing through the Restricted Section of the library.
Comment: @Binary: There is definately some talent associated with it. Remember, even Wormtail was able to learn how to do it, but it took him some practice, see book 3.
Comment: @Pearsonartphoto: I don't think we can discount Wormtale's ability as a wizard nor his intelligence.  He may have been described as a lump but he was able to pull off some fairly advanced spells; Avada Kedavra and the Dark Lord's resurrection are not simple acts of magic.  I'm voting for skill versus innate ability.  Look at the known animagi for relatively powerful wizards: James Potter, Sirius Black, Minerva McGonagall to name a few.  Even Rita Skeeter seems relatively competent... but, I digress...
Comment: @TGnat - Skeeter seems pretty competent, as you said. In my answer I linked to a list of her skills/spells, seems like she was NOT a magical lightweight.
Comment: @user296: yep, http://smbc-comics.com/index.php?db=comics&id=701#comic
Answer: First, general reference:
From http://harrypotter.wikia.com/wiki/Animagus:

Only very powerful and skilled wizards are able to become Animagi. The process of becoming an Animagus is long and arduous, and has the potential to backfire and cause the transformation to go horribly wrong. Once the initial training is over, an Animagus can change at will at any time, with or without a wand.

Animagus skill is a special type of transfiguration. It differs from general Transfiguration in 4 main ways:

First, and obvious, it transforms the body of a human into a body of an animal.
Second, it retains the mind of the wizard, as opposed to simple transfiguration of said bodies which leaves the brain capability of a target animal (e.g. no intelligence).
It does not require a wand or a verbal spell.
Target animal is always the same - like with Patronuses, you can ONLY Animagusate yourself into one specific form, determined by your personality as noted by JKR (it's never explicitly noted that it has to be the same animal as your Patronus, but there are no canon examples that break the 'Animagus form'=='Patronus form' pattern, and Patronuses are also determined by personality IIRC).

NOTE: Animagus transformation is definitely a very complicated skill:

General Human transfiguration is taught only to 6th years, a NEWT level skill. And obviously transfiguring yourself so that your brain continues to function as a wizard (as opposed to being turned into a real non-intelligent animal) is MUCH harder.
As an example, see the half-finished Shark transformation that Victor Krum did in Triwizard Tournament in HP4.
Also, in general wandless/voiceless magic is the most advanced/difficult one. Animagus skill would fit the same pattern.
In addition, most - if not all - mentioned Animagi seem like pretty powerful/skillful wizards - from Marauders to McGonagall to even Rita Skeeter to (according to Rowling's interview joke, so may it is not canon) Godric Gryffindor. There's also major fan speculation (not fully proven nor dis-proven) that Dumbledore was a likely Animagus as well.

Now, for more detailed answers for mini-questions you raised:

"how do you learn to do it beforehand?" "who would teach the course?"

As noted above, Animagus skill is a special type of transfiguration.
So presumably the training would be "Very Advanced" Transfiguration study. When done "officially" it would likely be taught in the form of private lessons by a good Transfiguration teacher/practitioner.
As for unregistered Animagi, probably someone taught them (may be by example - e.g. the Marauders) and may be just self-study for someone extremely capable.

"if you need a permit ... how do you learn to do it beforehand?" -

You don't require to be registered to participate in training. The primary reason for registration is to ensure the Animagi do not abuse their abilities, as the Ministry is able to keep track of them. Thus, until you actually obtain the ability and can practically complete the transformation, there is presumably no need to register.

"And as there's only 7 registered Animagus (I forget the reference, probably book 3), ... who would ... certify the person for that matter?"

To answer the second part (actual question), the registration is done by a random Wizard bureaucrat at the Improper Use of Magic Office in Ministry of Magic. It's not a certification proving that you have the skill, but merely adding your specific info to Ministry list so they can keep tabs on you if needed. To use everyday analogy, it's more like registering a car (as opposed to getting a driver's license).
To answer the first part, the 7 registered Animagi part was only pertaining to this century. The quote from Hermione (in a scene when Lupin was trying to convince Harry and Hermione and Ron that Scabbers was Wormtail) was:

"... We did Animagi in class with Professor McGonagall. And I looked them up when I did my homework -- the Ministry of Magic keeps tabs on witches and wizards who can become animals; there's a register showing what animal they become, and their markings and things... and I went and looked Professor McGonagall up on the register, and there have been only seven Animagi this century."
Comment: I'm curious about the veracity of that quote. There doesn't seem to be any canonical references that site to back up all of the specific claims made on that page...
Comment: @TGnat - added a couple of points to prove the difficulty of obtaining the skill. The rest of the quote is obviously collaborated by books (Krum's half-shark thing, and wandless transformation for Sirius Black)
Comment: Wasn't Wormtail an Animagus? He doesn't seem to fit the profile of a great and powerful wizard.
Comment: @JackBNimble - he managed the brew to get Voldemort his body. He managed the explosion that caused Sirius to be captured. He may not be an extra class wizard but he's not exactly total nothing magic wise either. Also, you don't need to be a powerful wizard in general, you need to be talented in transfiguration.
Comment: Gryffindor as the Giant Squid was from Rowling's old website, not an interview.
Comment: @ibid - that's what I get for using Wikia. Bad Dobby DVK!
Answer: You could either learn from the Ministry or in a very advanced Transfiguration class. But the Marauders and Rita Skeeter probably looked it up in the restricted section in the library and took them a long time to actually figure it out.
Comment: This doesn't answer the first part of the question.
Answer: It's not really explicitly stated. The way I read it was not "you need a permit" but rather all Animagi are registered.
I assumed it was something that required quite a bit of skill and training as well as some amount of natural predilection. Which explains why all the Animagi we know about seem only to have gain the ability in their teens or later.
As for how one would learn: I figured it's not the sort of thing the school is going to teach or put on the curriculum, but the schools do have rather extensive libraries, so one could learn on their own, or from someone else who has the ability. In the event that someone managed the transformation I would assume the ministry of magic would be monitoring the use of that magic (much as they're known to monitor some other use of magic) and would be in touch to get you registered.
Answer: You can learn it from textbooks and from your transfiguration teacher
The basic steps of the process are outlined in textbooks. (Actual textbook is unknown, but possibly Intermediate Transfiguration.)

Talent in both Transfiguration and Potions is necessary to become an Animagus. No responsibility can be taken for any physical or mental problems resulting from following these instructions.

For the space of one entire month (from full moon to full moon), a single leaf from a Mandrake must be carried constantly in the mouth. The leaf must not be swallowed or taken out of the mouth at any point. If the leaf is removed from the mouth, the process must be started again.
Remove the leaf at the full moon and place it, steeped in your saliva, in a small crystal phial that receives the pure rays of the moon ...
<code>[there are a total of ten steps listed]</code>
Pottermore - Animagi (behind paywall)

One did not have to learn this from a fellow Animagus. Anyone who was knowledgeable enough would work.

By the end of her education at Hogwarts, Minerva McGonagall had achieved an impressive record: top grades in O.W.L.s and N.E.W.T.s, Prefect, Head Girl, and winner of the Transfiguration Today Most Promising Newcomer award. Under the guidance of her inspirational Transfiguration teacher, Albus Dumbledore, she had managed to become an Animagus; her animal form, with its distinctive markings (tabby cat, square spectacles markings around the eyes) were duly logged into the Ministry of Magic's Animagus Registry.
Pottermore - Professor McGonagall
Answer: It's pretty much just a mix of innate skill and guidance from more experienced wizards, I believe. For example, Prof. Mcgonagall learned from Dumbledore when she was younger, even though he himself wasn't an animagus.
Comment: Do you have any in universe references to support this?
Comment: Also, how's this different than what's already in other answers?


How do I change the color depth of a monitor in Lion/10.7?

Question: How do I change the color depth of a monitor in Lion/10.7? I vague remember it being an option in the display prefs or the display menu bar in an older OSX version, but it seems gone in 10.7?
Comment: Why do you want to do this?
Answer: You're right in that Apple removed the option to switch between "Millions" and "Thousands" of colors from the Displays preference pane in OS X after Leopard (10.5).
I've not tried them, but something like Display Maestro or SwitchResX both appear to have the ability to change color depth and might help.
Comment: Thanks! Display Maestro seems to work, SwitchResX does not seem to have a color depth option in Lion.
Answer: I've discovered the Quicksilver Displays plugin changes color depth for Lion as well. If you use Quicksilver already (and you should) its very easy - search for the display name, choose the color depth action, and choose the depth you want. It's great for changing display size also.
A little more info is here - http://lifehacker.com/322363/top-10-quicksilver-plug+ins.


Is ISCSI flow 1MB/sec good for web server?

Question: In general, is it good practice to use iSCSI accessible SAN (Storage Area Network) for data storage in server?
Answer: There's no such thing as 'in general' it depends on your requirements. iSCSI isn't an internal storage mechanism - that is it's not how you'd link a disk directly inside a server, it's slow and needlessly complex for such a job where SATA or SAS would be far better.
In terms of speed iSCSI works at whatever the interface is so typically 100Mbps, 1Gbps and 10Gbps - equating to ~10MBps, 100MBps and 1GBps though only if the actual disk array can keep up and the controller/s aren't too busy serving other requests.
Now onto whether it's right for you, the first thing to know is that iSCSI is block-level storage, it's up to the client machine's file systems (which obviously varies based on OS) to mount, partition, format and manage this block-level storage. Most filesystems aren't cluster-aware meaning that they can't share this data with any other machine/s unless they're all using the exact same cluster-aware file system. This is an important distinction, as some software requires block-level storage. The other main block-level storage system is Fibre-Channel which uses a dedicated network, usually at 1, 2, 4 or 8Gbps but usually has far less network contention that iSCSI.
iSCSI is not a NAS file system which allows for file-level sharing such as NFS, CIFS/SMB, HTTP, FTP/SFTP etc.
So if all depends on what you're trying to achieve - let us know and we'll be able to help you better.
Answer: I use iSCSI for SAN backed Clusters; works great, but if you're getting 1MBps, something's probably wrong. The SAN I use daily does 120MB+ sustained.


What is difference between hamd and shukur?

Question: I was reading a tafseer of Al-Fatiha (in Turkish), and it is mentioned on that text that there are 2 kinds of ni'met (benediction), one is material and other is spiritual. It says that we shukur (thanks) to Allah for material ni'mets, and we hamd (thanks) to Allah for spiritual ni'mets. I thought both of them meant thanking. Can anyone explain what exactly hamd and shukur means and what is the difference between them?
Answer: Great question! I was taught that the main difference between hamd and shukr was that shukr was thanks given after a favor was done. Someone does you a favor, helps you out, gives you something - and you give them shukr in return. It's given in return for some kind of personal benefit. Hamd on the other hand includes shukr but also has an additional connotation of not being given in return for anything - it is praise that is given regardless of whether someone did you a favor or not, it is praise given because of who they are, not what they did. In Islam, we say Allah SWT is Al-Hameed - He is the One who is deserving of Praise always, whether He has done something for us or not, whether we praise Him or not.
Hans Wehr defines hamd as praise, commendation, or laudation and shukr as thankfulness or gratefulness or thanks, which roughly follows what I said above.
References:
1. Class on Names of Allah taught by Ustadha Muslema Purmul, 2009.
2. Hans Wehr dictionary
Comment: Do you really own a copy of Hans Wehr? Is it as useful as it's supposed to be?
Comment: I do own a copy and it is actually very useful. I've heard that Lane's lexicon or ibn Manzoor's Qamoos is more beneficial for more advanced students though.
Answer: Good Answer by Ansari. There are several differences. I would like add something to his answer.
Al-Hamd necessarily happens through tongue. However, ash-shukr is possible with the tongue as well as with action.
So, from the point of view of where it occurs, ash-shukr is more general than al-hamd, because it includes the praise of the tongue and the action, and al-hamd is more specific because it only occurs by the tongue.
Allah says in Qur'an:

اعْمَلُوا آلَ دَاوُودَ شُكْرً‌ا
"Work, O family of David, in gratitude." [Surah Saba 34:13]

That is an example of Ash-Shukr through action.
And if you see from the point of view that Ansari mentioned i.e. for what it is praised, then Al-Hamd is more general.
Source: Difference between al-Hamd and ash-Shukr
Comment: +1 for pointing out another difference. Perhaps you want to include that ayah from the Qur'an: "i'maloo aala Dawooda shukra" - where the people of Dawud (as) are being commanded to "do" thankfulness.


What are the primary investment strategies people use and why do they use them?

Question: When I first started studying investing the literature I was reading pointed me towards something called technical analysis.  As I started asking questions about this trying to determine exactly what this meant, I started to discover that technical analysis is actually a somewhat controversial investment strategy.  So, my question is what strategies are out there, what defines them, and why would anyone choose one over another?
Answer: There are two umbrellas in investing: active management and passive management.
Passive management is based on the idea "you can't beat the market." Passive investors believe in the efficient markets hypothesis: "the market interprets all information about an asset, so price is equal to underlying value".
Another idea in this field is that there's a minimum risk associated with any given return. You can't increase your expected return without assuming more risk. To see it graphically:

As expected return goes up, so does risk. If we stat with a portfolio of 100 bonds, then remove 30 bonds and add 30 stocks, we'll have a portfolio that's 70% bonds/30% stocks. Turns out that this makes expected return increase and lower risk because of diversification.
Markowitz showed that you could reduce the overall portfolio risk by adding a riskier, but uncorrelated, asset! Basically, if your entire portfolio is US stocks, then you'll lose money whenever US stocks fall. But, if you have half US stocks, quarter US bonds, and quarter European stocks, then even if the US market tanks, half your portfolio will be unaffected (theoretically). Adding different types of uncorrelated assets can reduce risk and increase returns.
Let's tie this all together. We should get a variety of stocks to reduce our risk, and we can't beat the market by security selection. Ideally, we ought to buy nearly every stock in the market so that  So what's our solution? Why, the exchange traded fund (ETF) of course!
An ETF is basically a bunch of stocks that trade as a single ticker symbol. For example, consider the SPDR S&P 500 (SPY). You can purchase a unit of "SPY" and it will move up/down proportional to the S&P 500. This gives us diversification among stocks, to prevent any significant downside while limiting our upside.
How do we diversify across asset classes? Luckily, we can purchase ETF's for almost anything: Gold ETF's (commodities), US bond ETF's (domestic bonds), International stock ETFs, Intl. bonds ETFs, etc. So, we can buy ETF's to give us exposure to various asset classes, thus diversifying among asset classes and within each asset class. Determining what % of our portfolio to put in any given asset class is known as asset allocation and some people say up to 90% of portfolio returns can be determined by asset allocation.
That pretty much sums up passive management. The idea is to buy ETFs across asset classes and just leave them. You can readjust your portfolio holdings periodically, but otherwise there is no rapid trading.
Now the other umbrella is active management. The unifying idea is that you can generate superior returns by stock selection. Active investors reject the idea of efficient markets.
A classic and time proven strategy is value investing. After the collapse of 07/08, bank stocks greatly fell, but all the other stocks fell with them. Some stocks worth $100 were selling for $50. Value investors quickly snapped up these stocks because they had a margin of safety. Even if the stock didn't go back to 100, it could go up to $80 or $90 eventually, and investors profit.
The main ideas in value investing are: have a big margin of safety, look at a company's fundamentals (earnings, book value, etc), and see if it promises adequate return. Coke has tremendous earnings and it's a great company, but it's so large that you're never going to make 20% profits on it annually, because it just can't grow that fast.
Another field of active investing is technical analysis. As opposed to the "fundamental analysis" of value investing, technical analysis involves looking at charts for patterns, and looking at stock history to determine future paths. Things like resistance points and trend lines also play a role. Technical analysts believe that stocks are just ticker symbols and that you can use guidelines to predict where they're headed.
Another type of active investing is day trading. This basically involves buying and selling stocks every hour or every minute or just at a rapid pace. Day traders don't hold onto investments for very long, and are always trying to predict the market in the short term and take advantage of it. Many individual investors are also day traders.
The other question is, how do you choose a strategy? The short answer is: pick whatever works for you. The long answer is:

Day trading and technical analysis is a lot of luck. If there are consistent systems for trading , then people are keeping them secret, because there is no book that you can read and become a consistent trader. High frequency trading (HFT) is an area where people basically mint money, but it s more technology and less actual investing, and would not be categorized as day trading.
Benjamin Graham once said:

In the short run, the market is a voting machine but in the long run it is a weighing machine.

Value investing will work because there's evidence for it throughout history, but you need a certain temperament for it and most people don't have that. Furthermore, it takes a lot of time to adequately study stocks, and people with day jobs can't devote that kind of time.

So that leaves us with passive management. This is, in my opinion, the best idea for individual investors. That's because most active management firms actually underperform the market (both in the short and long run), and individuals can't dedicate the time necessary to become great investors (most can't).

So there you have it. This is my opinion and by no means definitive, but I hope you have a starting point to continue your study. I included the theory in the beginning because there are too many monkeys on CNBC and the news who just don't understand fundamental economics and finance, and there's no sense in applying a theory until you can understand why it works and when it doesn't.
Comment: @pacerier: I cite my father's observation, as the ad man for a major stock market statistics product: He could not imply that the product would actually be useful to the investor, due to the risk of false-advertising laws. He _could_ call it "_The Information You Want_", because by definition if they were buying it they wanted it, whether their reasons for wanting it were well-founded or not. I'll also point out that if the things disclosed in the books worked at all reliably, the authors would be rich enough not to need income from a book.
Comment: If you say technical analysis / day trading is just luck, do you also mean to say that books like this http://www.amazon.com/Forex-Patterns-Probabilities-Strategies-Range-Bound/dp/0470097299 are scams?
Comment: One other comment: some of us do passive trading because even if one could beat the market, we believe doing so would burn enough of our time and attention that the additional gains are unlikely to repay what those personal resources are worth to us. I value my hobby time at $40/hour, for things I enjoy doing. Having to do something I don't enjoy pushes the value of that time much higher. Since I don't enjoy micromanaging my money, it would take high probability of very significant  additional returns to make active management worth considering... and I don't like the odds.
Comment: Excellent, apart from your one comment "Day trading and technical analysis is a lot of luck."
Answer: Your question seems to be making assumptions around "investing", that investing is only about stock market and bonds or similar things. I would suggest that you should look much broader than that in terms of your investments.
Investment Types
Your should consider (and include) some or all of the following for your investments, depending on your age, your attitude towards risk, the number of dependents you have, your lifestyle, etc.

Life insurance, disability insurance, unemployment insurance (note I'm not an insurance broker, just think there is value in some of these, for some people, some of the time)
Property. Owning a property depending on the country and the tax laws can make this a good medium to long term investment. Multiple properties can be quite valuable in terms of the buy-to-let market. These are usually illiquid assets that in the long term have a capital gain.
Investment in a business. Owning or investing in a business that you can put your personal skills and expertise into is a great way to earn money and build value. Also generally medium to long term, though with online business, medium tern can be 3-5 years.
Stocks and shares. These can be traded anywhere from high frequency trading, day trading, trading (weeks-months), investing (often years)
Government or corporate bonds. These can be traded much as stocks and shares are, or can be bought and held, receiving the interest as per the bond description.
Commodities. I know of individuals who buy and sell precious metals – Au, Ag, Pt. Im sure others are possible, often these are over a time frame of months to years
ETFs, which can be in almost any stock, share, index, bond or commodity, these can be traded in the same frequency as stocks and shares, though haven't been around very long so they haven't been owned for many years yet.
Futures, options and other derivatives. These are traded similarly to stocks and shares.
Foreign exchange trading. These can be used as a hedge for business, but are traded in HFT, day trading and short term (days-weeks).
Premium Bonds (http://www.nsandi.com/), a UK special 'investment' that is capital guaranteed, but the bond holder is entered into a lottery that may "pay out" if you are a winner. A very strange beast, but was recommended to me as being better than cash by an investment broker due to the current low interest reates!

I love @Blackjack's explanation of diversification into other asset classes producing a lower risk portfolio. Excellent! All the above need to be considered in this spread of risk, depending as I said earlier on your age, your attitude towards risk, the number of dependents you have, your lifestyle, etc.
Stock Market Investment
I'll focus most of the rest of my post on the stock markets, as that is where my main experience lies. But the comments are applicable to a greater or lesser extent to other types of investing.
We then come to how engaged you want to be with your investments. Two general management styles are passive investment management versus active investment management. @Blackjack says

That pretty much sums up passive management. The idea is to buy ETFs
  across asset classes and just leave them.

The difficulty with this idea is that profitability is very dependent upon when the stocks are purchased and when they are sold. This is why active investing should be considered as a viable alternative to passive investment.
I don't have access to a very long time frame of stock market data, but I do have 30 or so years of FTSE data, so let's say that we invest £100,000 for 10 years by buying an ETF in the FTSE100 index. I know this isn't de-risking across a number of asset classes by purchasing a number of different EFTs, but the logic still applies, if you will bear with me.
Passive Investing
I have chosen my example dates of best 10 years and worst 10 years as specific dates that demonstrate my point that active investing will (usually) out-perform passive investing.
From a passive investing point of view, here is a graph of the FTSE with two purchase dates chosen (for maximum effect), to show the best and worst return you could receive. Note this ignores brokerage and other fees. In these time frames of data I have …

Best return if you happen to buy your stocks at April 2003 and sell at March 2013. The return is 23% profit
Worst return if you happen to buy your stocks at July 1999 and sell at June 2009. The return is a 32% loss

These are contrived dates to illustrate the point, on how ineffective passive investing can be, depending if there is a bear/bull market and where you buy in the cycle.  One obviously wouldn't buy all their stocks in one tranche, but I'm just trying to illustrate the point.
Active Investing
Let's consider now active investing. I use the following rules for selling and buying:-

Buy the ETF (or continue holding the EFT) when the 3 month moving average of monthly close price is greater than the 7 month moving average of close price.
Sell the ETF (or stay in cash) when the 3 month  moving average of monthly close price is less than the 7 month moving average of close price.

This is obviously a very simple technical trading system and I would not recommend using it to trade with, as it is overly simplistic and there are some flaws and inefficiencies in it.
So, in my simulation,

For the worst 10 year period, I did a total of 16 trades and made a profit of 21%
For the best 10 year period, I did a total of 15 trades and made a profit of 71%

These beat the passive stock market profit for their respective dates.
Summary
Passive stock market investing is dependent upon the entry and exit prices on the dates the transactions are made and will trade regardless of market cycles.
Active stock market trading or investing engages with the market using a set of criteria, which can change over time, but allows one's investments to be in or out of the market at any point in time.
My time frames were arbitrary, but with the logic applied (which is a very simple technical trading methodology), I would suggest that any 10 year time frame active investing would beat passive investing.
Answer: In a book I enjoyed [1] there were two broad types of investing/trading strategies:

"Momentum" or "trend following" - these assume that prices move continuously as information, evaluations, and opinions gradually change among market participants. As such, if one sees a price start going up, one buys.
"Mean reversion" - these assume, to the contrary, that prices fluctuate randomly around a fixed value, and can't go forever in one direction. After one sees a price going up, they "sell high".

All trading strategies fall into one of these two categories, and one can tell which one they're using statistically [2].
The book author's former employer, Man Group AHL, is a trend-following investment fund. They generally have lots of small losses (when there is no trend), but large gains occasionally (when the market shifts).
The author employs such a trend-following rule, but also a "mean-reversion" rule to complement it: "carry trading", which borrows a currency with low interest and lends a currency with higher interest (but the risk here is that the exchange rate goes unfavorably).

[1] Systematic Trading by Rob Carver
[2] The skewness of the return distribution is one measure, and the Rachev ratio is another.


What is the blurred light effect in this portrait?

Question: Id like an explanation for how the blue background light in this photo is somehow "overlaying" the model's hair and the back of the chair. How could this effect be setup and reproduced?
Comment: Looks like a mistake to me!
Answer: Probably, the effect might be achieved with the help of slow sync flash method (a combination of slow shutter speed and firing flash). Not much lighting involved other than the on-camera flash. As the subject is crisp when the flash is fired and the blur caused with the long shutter speed. The reflections on the lips confirm that the flash is fired.
Reproduction: Being more accurate the effect might have used rear curtain Sync. In this the model might have moved slightly front after the shutter is pressed (probably with chair, as overlays are on chair also) and then flash that is fired at the end of the capture would have frozen the subject sharply. This effect can be reproduced on an moving subject, with motion effect by the same time freezing the subject.A lot more images can be found here: http://www.flickr.com/groups/slowsynch/pool/
Answer: It's a long exposure plus flash.
The clue is that the only blurring is coming from the window light. The subject is heavily backlit, without the flash they would be a silhouette. The flash momentarily illuminates the subject, and because that area would be black otherwise no light from the subject is recorded during the period that the camera is moving hence there is no motion blur at alp on the subject.
It doesn't matter whether it was first or second curtain flash as the subject was stationary you don't have the problem of motion blur being in front of the subject.
Answer: This technique could be reproduced by using a long exposure and a zoom lens.
With an exposure of say, 2 seconds, right after the shutter is pressed, quickly zoom out by a few millimeters and keep the lens at that second for the duration of the shot.
The blurred images looks like a motion blur moving toward the model. Quickly zooming out would create this blurred "overlay," with the model in focus once the zoom has settled.
Comment: It would be impossible to obtain such a sharp image using your method, **especially at the edge of the photo**. I believe the photo is created with flash plus a long exposure, not the zoom that you have suggested.
Answer: It does look like slow sync, although I'm not 100% convinced, given the static subject. You could reproduce that in post processing by duplicating the layer, giving it a heavy blur (50px or more) and then roughly masking back in the in-focus parts of the image.
Comment: You *could* do that in post but it would be much more difficult than just shooting the image with flash and then moving the camera.


Model format for small game

Question: I'm writing my own small-time game from scratch, and now I'm looking to start creating models. I've been wondering- what is the best model format to use? Given that I will be writing the model loading code myself and using whatever program generates them. Ideally, I'd look for a format that has fairly wide support between modelling programs, so I can pick the one I like most to actually perform the building, and the format itself would be relatively simple to load, rather than having all of the latest features.
Comment: Collada DAE is an exchange format that most tools can output to. Its up-straight, good ole XML.
Comment: What would be your first choice in terms of a modeling tool?
Comment: @Josh Petrie: I don't really have any experience with modelling tools, which is why I was looking for larger support- so that I could experiment and pick a tool *after* building my model system and checking that it works.
Answer: I have used Value's SMD format for a while to good effect (there's an extremely bare bones loader checked in to the SlimDX repository; it's in C# but it should be easily translatable to C++). I picked it because it was straightforward to load and debug (since it's a text-based format), supported textures and skeletal animation, and was natively supported by the XSI Mod Tool.
I used it as an interchange format which was eventually compiled down to a proprietary binary format.
Although it seems like Valve has replaced SMD with DMX, which I don't know much about.
.X is a reasonable choice as well -- although it's being phased out to a degree by the DX SDK, it's still possibly to load the files even in later versions of Direct3D (if you don't mind round-tripping through the 9 D3DX interfaces) and you can find exporters for just about every modeling tool out there.
.obj is also common, but lacks animation support (if that matters).
If you don't mind setting up a longer asset pipeline, and cannot find a combination of format + modelling tool + exporter that works for you, you might consider looking in to FBX or Collada. They're both interchange formats -- so you probably don't want to load them directly (Collada, in particular, is painfully verbose), but you may be able to construct an asset transformation pipeline using the tools associated with both formats to allow you to use the model format you want with the modelling tool you like best.
Answer: Since you've tagged DirectX, you could use .X meshes. You can then export 3D Studio Max models using the Panda Exporter (Found here: http://www.andytather.co.uk/Panda/directxmax.aspx)
If you don't want to use the DX meshes for any reason, you could potentially use Lib3DS (Found at: http://code.google.com/p/lib3ds/) Although it's not very well documented and you might end up pulling your hair out :) There is a tutorial on using it here: http://www.donkerdump.nl/node/207
The advantage here is that you don't need to export your .3DS meshes.
Of course if you want the format to be used in a wide variety of modelling programs, then you're probably going to need an exporter (Like Panda above). You could also use the .OBJ format which is a human readable file, so it's not too difficult to parse and write some loading code for it. I'm no expert in OBJ files, since the .X format has been suitable for my needs so far.
Hope that helps.
Answer: If you want to use non-animated models and want to write your own loader, I would recommend OBJ format. I have used it several times and it's simple and easy to load.

Model format for small game


How to find its closed-form?

Question: here is a sequence defined by the below recursion formula:
$$a_n=2a_{n-1}+a_{n-2}$$
where $n \in \mathbb{N}$ and $a_0=1,a_1=2$.how to find its closed-form.
Comment: There are a couple of standard approaches. Have you used *generating functions*?
Answer: If we write $E^ra_n=a_{n+r},$
the characteristic/auxiliary equation becomes $E^2-2E-1=0,E=1\pm\sqrt2$
So, the  complementary function $a_n=A(1+\sqrt2)^n+B(1-\sqrt2)^n$ where $A,B$ are indeterminate constants to be determined from the initial condition.
$a_0=A+B,$ But $a_0=1$ So, $A+B=1$
and $a_1=A(1+\sqrt2)+B(1-\sqrt2)=2$
Now, solve for $A,B$
Comment: wow , I think that's very nice idea using ode. Can you suggest some readings for these ideas.
Answer: To put it simple: Use a power trial function $a_n=q^n$ to find a solution disregarding the initial conditions (there will be two solutions $q_1$ and $q_2$ that can work). Next make a linear combination $Aq_1^n+Bq_2^n$ to match the initial conditions. Note that a linear combination is automatically also a solution.

How to find its closed-form?


Links to other sites in dropdown menus

Question: I work for a company that has several sites. They have requested I put links to the smaller sites in a drop down menu on the menu bar. Is this a good practice or should they be seperate.
Also there are already links to the other sites on the sidebar.
Comment: Can you provide some more details and a mockup of what you are talking about?
Answer: I've seen this done in two different ways--organization between sister sites.

The drop down menu as you mentioned e.g. http://www.nike.com/
List all the sites (less scalable) in an auxiliary type header e.g. http://www.bbc.com/news, Google, http://www.popsugar.com/

Both these solutions work if all the sites in the family share a common header or a visual language. It breaks down when one site goes rogue. In fact, BBC did an excellent case study on exactly how they approach this type of problem among other complexities (e.g. content type, localization): http://www.bbc.co.uk/blogs/bbcinternet/2010/02/a_new_global_visual_language_f.html
I have never seen it on the sidebar, and I can think of a couple of reasons why I wouldn't put it there:
- Horizontal real-estate is more expensive than vertical real-estate
- A sidebar has a strong precedent of being used for local navigation
- If I am a user, and I am looking to switch context site-wide, the header is the place I'd begin looking. The sidebar is halfway down the screen.
Answer: It's all about setting user expectations. Most users assume that clicking a menu item will take them somewhere within the website. There are plenty of website examples though where even clicking on a main navigation menu item takes a user to a different domain (the Ubuntu QA site on Stack Exchange is an example). The best examples though mimic the previous website's design within the new website as much as possible. Sometimes though that's not an option. In those cases, give the user some sort of visual cue that the menu item is an outbound link. This is commonly communicated with an arrow leaving the top right of a square.
Answer: Drop down menu is a control which allows to select one item among list of items. If it is your case just use it. A problem could occur with visibility and readability of URL in list. So you could shorten URL by hidding protocol section (http://) like it is in a browser's address bar.
Answer: I've seen something similar from Envato and their many websites.
If the other websites are similar in theme and layout, this may be a viable option to pursue.

Links to other sites in dropdown menus


When does a reaction equation require the reversible sign and when does it not?

Question: Sometimes my professor puts the $\to$ symbol and sometimes he uses $\leftrightharpoons$. How do I know which to use? I get that one means the reaction only heads one way while the other means that the reaction holds at an "equilibrium" where the reactants are converting into products and the products are converting into reactants. But if I'm only given a word problem that lists 2 reactants and their concentrations, how do I know which to use?
Comment: Probably you should ask some guys who know teacher's preferences, which may be quite artificial.
Comment: @Mithoron That would connote a teacher the needs to be educated. ;-)
Answer: You just need to learn and know. Luckily, there is a certain logic to the question which reactions can be reversible and which cannot. However, a full list is impossible and would exceed the space of this margin.
For most mechanisms, there is (at least) one point-of-no-return step. Learn to identify this step. All other arrows should probably be $\ce{<=>}$, if you're strict. These non-reversible steps are often (but not always!) carbon-carbon bond forming reactions, as a very rough guideline on which is which.
Comment: I wonder who downvoted me and why?
Comment: Hmm ok. But there seems to be a particular brand of equations for which my professor always uses the single arrow. I think they were called dissolving/ionization equations? I may be wrong though.
Answer: Ask yourself if it is reasonable to give thought to the backward reaction. If not, because it is not relevant for the particular question, use the single arrow.
E.g. for partial equations, usually the single arrow is used, because statements about the equillibrium only make sense for the full reaction.


August 30th 2018 Soyuz leak, any dangers for re-entry?

Question: On August 30th 2018, Soyuz MS-09 had a leak that was fixed by the ISS crew (source).
Does the leak/fix have any consequences on using the Soyuz for returning to Earth?
Would the fix hold the stress caused by re-entry?
Answer: The leak is in the Orbital Module (OM), which is jettisoned prior to re-entry, so there is no concern there.
Source: link in the question.

Image source: spaceflight101.com
Comment: Oh yes of course. It's so obvious I missed it. So obvious it even took me a few minutes to understand your answer. I know the Soyuz is the whole thing but somehow my mind associates the Soyuz to the re-entry module, probably because I find re-entry the most impressive.
Comment: Russian media is reporting that the hole was drilled in error on the ground, not a strike in orbit! http://www.parabolicarc.com/2018/09/03/report-hole-soyuz-spacecraft-caused-drill-debris-strike/
Answer: There is no concern about the safety of re-entry because the leak was in Orbital Module that is jettisoned before atmosphere reached. Crew is located in Reentry Module.
But if the leak could not be sealed it would be a huge problem for the Soyuz and ISS. According to this ISS was losing its air

of around 0.6 millimeters of mercury (0.8 millibars) per hour

so the whole ISS would be depressurised in several weeks. So if the leak could not be sealed the most probable outcome would be aborting Soyuz MS-09 mission and returning its crew of 3 to Earth as soon as possible (but not immediately - it would need to wait until orbit alignment allows return to nominal landing site in Kazakhstan).
ISS mission managers are very cautious about safety, so any alternatives would be considered as too danerous, I think. I see the alternative as to close hermetically both hatches of the Soyuz and let the Orbital Module to depressurize without impact on mission. After mission ending the Orbital Module would be repressurised again and the crew returns to Earth. Most probably it would work but there are some minor chances that something goes wrong - for example the crew can't open sealed Soyuz hatches, or the leak hole widening (if it's technical defect and not a meteoroid impact).
For the return to Earth the leak at actual rate would not be dangerous. The only difference would be the crew sitting in Return Module and sealed from Orbital Module immediately after depart from ISS. It's usually needed 3-6 hours from ISS depart to landing of Soyuz.
If the leak was in Reentry Module it would be some more problematic, but maybe manageable. Soyuz crew wears Sokol launch and reenry suits that protect them from depressurization. The hole could be concern for reentry if it would contact with hot plasma (remember Columbia disaster). So it depends on position of the hole. If it is on the upper part of Reentry Module it would not contact the plasma at normal reentry (it would lead to early separation of Reentry Module to avoid ballistic reentry scenario where Souyz re-enters atmosphere top-first).
I think  there are good chances that Soyuz MS-09 would be aborted completely if the hole was in Reentry Module, as well as if the hole was in Orbital Module but much bigger. It would mean that Soyuz MS-09 should be undocked and automatically deorbited, and new Soyuz craft should be sent unmanned as soon as possible to ISS as replacement.
Comment: @DP_: [Yes](https://space.stackexchange.com/questions/14486/minimum-crew-of-soyuz-tma-m)
Comment: Thank you for so many _would_ and _if_. Even though not actual, very interesting perspectives!
Comment: Re *new Soyuz craft should be sent unmanned as soon as possible to ISS as replacement.*: Can a Soyuz fly unmanned to the ISS and dock to it?
Comment: @DP yes, in this case Soyuz is operating automatically like Progress cargo ship does. Also ISS crew have TORU system inside ISS for manual control of spacecraft if something goes wrong. https://en.wikipedia.org/wiki/TORU
Answer: The other answers do an excellent job, but since I happened to have just viewed this (currently) six year old NASA Johnson video Inside the Russian Soyuz Spacecraft I thought I would include a visual explanation.
Here are some screen shots and a brief transcription of some of the information explained by NASA astronaut "Mike Fincke, a veteran of the Soyuz and Shuttle..."
It sounds like the separation doesn't happen until just before reentry, so while the forces, vibrations, heat loads etc. from reentry doesn't matter, you would need the hole to stay plugged until that time, and while it might be only a few hours, there is a possibility that you would like the option to delay reentry if some unforeseen circumstance arose.

Right above it we have the habitation module; when we get into space we need a little bit more room so we're not cramped in that "little can" […] Now just before landing, all three of these modules separate, and only the part in the middle, where we're sitting, is the one that comes back home.

We're all in our space suits again, we make sure that this hatch especially, the one between the living/habitation module and the crew module here is very fully sealed, because all of a sudden that one is going to be the hatch to the outside because our three compartments break apart.


What is the justification for locking votes?

Question: Why am I not allowed to change my vote after some period of time? There are times when I go back to things I voted on, and decide they didn't deserve that specific vote. (I get wiser as I grow older)
Comment: The site's developers never make mistakes, so you're not allowed to either.
Answer: The justification of Jeff to prevent the "tactical downvoting" is not good enough.
It could be prevented by different approach, as I suggested in https://meta.stackexchange.com/a/135243/163139
The time limit to undo  up-vote could be completely removed.
When user tries to undo downvote, it should be allowed after time limit(currently 5 min), but do not refund reputation point.
These changes will allow users to freely undo their up and down-votes but still will prevent unhonest "gamers" to restore points by undoing down-votes.
Comment: But locking votes doesn't prevent initial down-vote to have her/his answer with the higher score. You just confirmed that locking votes is useless to fight tactical down-votes.
Comment: It's not a matter of getting back a −1 from a tactical down-vote; it's a matter of gaining reputation because the answer is the one with the higher score. Who uses tactical down-votes hopes to get more up-votes because her/his answer has the higher score. If then the user is also the first one to answer, there are possibly more chances for her/him to get more up-votes.
Comment: I am not proposing to prevent the initial down-vote. I am proposing to remove locks.Locking is not required, if it is only tries to prevent such wild cases. Set up patterns of suspicious users behavior in logging system and report it to moderators will be more adequate measure.
Comment: @YatharthROCK wrong link, it should be http://meta.stackexchange.com/questions/146353. "posts" stub is used only when we want to see revisions or timeline.
Comment: @kiamlaluno: *"It's not a matter of getting back a −1 from a tactical down-vote; it's a matter of gaining reputation because the answer is the one with the higher score."*  Locking in votes doesn't prevent that.
Comment: @kiamlaluno: No it doesn't.  Locking in votes does not in any way prevent you from downvoting all other answers to make yours get listed first.  All it does is prevent you from undoing the damage afterward.  It makes tactical downvoting **more** harmful, not less.
Comment: I would appreciate a comment from downvoter explaining what's wrong with my suggestion.
Comment: What you are proposing doesn't prevent the initial down-vote either; plus, your system would not return the reputation to the user who initially down-voted a post, and removes her/his down-vote when the post is edited to make it better. Locked votes are useful in at least a case: Try down-voting 10 different posts written by the same user, in 10 seconds.
Comment: @Michael You're right. This make so much more sense than ChrisF's answer. This kind of hopeless voting makes me wonder about where SO is going...
Comment: See http://meta.stackoverflow.com/posts/146353
Comment: @YatharthROCK, link 146353 doesn't work
Comment: @MichaelFreidgeim I think you're already following the post: http://meta.stackexchange.com/questions/146353/suggested-edits-unlock-votes-on-old-posts
Comment: I thought SO would automatically redirect you as the number's unique (right?). Won't links become dead if the title changes? That's bad for search engines and for permalinking to a post...
Comment: @endolith It prevents I down-vote 20 answers given by other users just to have my answer listed as first.
Answer: Basically it's to stop people gaming the system.
One of the ways people did this was by down-voting rival answers and then removing that vote when their answer gains popularity. There are others.
See the following blog entries:
https://blog.stackoverflow.com/2008/12/vote-fraud-and-you/
https://blog.stackoverflow.com/2009/03/more-voting-anomalies/
Comment: Why would they bother removing the vote? To feel less evil? Maybe I don't understand the 'gaming' thing.
Comment: @ChrisF: It doesn't do much to stop the problem, though.  With votes locked in, people will just downvote other answers and leave it that way.  If you earn 20 points and lose 5, you're still ahead.
Comment: The op's original premises are still valid however and some votes should be removable as we learn more. Since gaming is done in conjunction with writing an answer of your own, could that detection criteria be put in so that if I don't have an answer to the same question, I should not be affected
Comment: @Tshepang IKR! Locking won't prevent the initial downvote, nor provide any other benefit. It will only agitate and annoy more users. It;s called freedom to change your mind...
Comment: @RobertHarvey Well, lots of things. For example, after reading the other answers you may have decided the approach was bad or incomplete. Basically seeing it in a new perspective. I don't mind not getting my +1 rep back, I just want to take back my vote.
Comment: @Tshepang: "Why would they bother removing the vote?" To overcome the maximum-votes-per-day limit?
Comment: By the way, none of those two blog posts address my question.
Comment: @Tshepang: "Why would they bother removing the vote?" The vote was added simply to make their answer look better, if nothing else removing it refunds the -1 it cost.
Comment: I know not what you mean by elliptical, but while scanning meta.SO, I did come across that question, and as you may have noticed, there wasn't really a proper justification.
Comment: @RobertHarvey: A 100% correct answer about software can become 100% incorrect when that software changes its API or deprecates a feature.  No edits, no comments, no changes whatsoever to the question or the answer, but the answer *becomes* incorrect because the outside world changes.  Obviously we should then be able to change our votes so that visitors are not mislead.  "Tactical downvoting" should be handled by rep penalties, not by locking-in erroneous votes.
Comment: Sometimes I upvote a great sounding solution that had a lot of votes (on StackOverflow), only to find it did not work (for example, was supposed to work for desktop and touch devices, but only works on desktop). When this happens, upvote should be removable. Also, sometimes I downvote only to find I made an error when trying it out, and it DOES work when I fix my mistake - so, I want to change my vote to upvote. Maybe users with high enough reputation should be able to change their vote.
Comment: @Tshepang - ah, I was sure they did. I'd have to go hunting here on meta for the evidence though you could check out the "Related" questions that mention "vote too old"
Comment: There's an elliptical comment on Jeff's answer to [this question](http://meta.stackexchange.com/q/23701/59303)
Comment: @YatharthROCK: Unless the post you voted on is edited, what need is there to change your vote?
Comment: Uhm, so what? People want to downvote only so they have a better chance at getting upvotes? I don't really see the problem. How many downvotes can you actually accumulate on a single post in this way?
Answer: I propose a script that detects "tactical voting" instead of locking votes, similar to the script that detects serial voting. If a user accrues enough instances of detected tactical voting, a moderator can investigate and temporarily ban them for "voting irregularities."
Comment: This space is exclusive for publishing answers to questions asked on the page. Do not use it to suggest new features. To make suggestions for new functionality, the platform creates a new question explaining your proposal.


Should beginning/indie game developers target multiple platforms initially?

Question: Partially as a response to How do game developers target multiple platforms (Xbox 360, PS3, PC and Linux)? but mainly because there are people on here with published games, should cross platform be the first requirement/feature for a developer trying to break into the business?  I have always been a believer (in a totally procrastinating sort of way) in picking either a 'niche' or 'mass market' platform and porting later if demand justified it.  Cross platform always felt like an artifical barrier to entry.  Why shouldn't we all write iPhone, Windows, or Browser games?
Answer: Especially if it's your first serious project, getting something (anything) actually completed is going to be your biggest challenge. The more barriers you can remove from that goal, the better.
If you're really serious, to give some thought to making your game port-able. If it's a stand-alone Windows application and you're doing your own rendering, don't write everything straight to DirectX. If you ever want to do something that's not Windowx/XBox, you'll need to rip all that out. And that's an unpleasant process once you've stopped looking at the code for more than a week or two. Put in some amount of abstraction if you think seriously think you'll ever want to port it.
That's assuming you've written your own engine, of course. All things being equal, I'd start with Unity or something similar. It removes a lot of those initial barriers for you.
Comment: For the love of god don't put a rendering abstraction layer in your first project! Premature abstraction layer building is leading cause of heart disease amongst programmers worldwide. Seriously though, it threatens to derail your project and you'll more than likely want to rewrite your engine heavily for the next thing you make anyway.
Comment: Couldn't agree more. Make the game. The amount of programmers that never finish a game because they keep coming up with 'da best architecture evar' is staggering.
Answer: I would agree with you on this one. If you spend all of your time building a cross platform game, it will never get out the door. I think it's best to try to predict which market it would succeed best in, and built your game to target that marker. If the game does really well, then you should consider porting it to other markets that make sense. If the game doesn't do well, and you think it could do well on another market, you might consider porting it anyway.
Answer: No. The whole idea about being an indie is that you can do what works for you, or what you believe is best (for your game, for you, or for your audience). The whole idea about being indie is that there is no 'must', 'should', or 'have to'. Make a game - your game. If it's a hit, or if you, after doing it, feel the need to port it, by all means. If it's not extremely targetted to specific hardware, or in some esoteric language, the main idea should be portable enough regardless. You're an indie, do your thing. YOUR thing.
Answer: Ruling out consoles briefly, I believe there's no reason the majority of PC games could not be developed for Windows, Mac and Linux simultaneously. Provided you put the work in at the beginning to get a system agnostic platform to work with, there's not going to be any huge blockers, and there will be advantages.

Compiling your code for different systems will show you issues that may have otherwise gone undetected. This can be simply from different compilers warning about different things, but also via the use of other tools not available for other platforms, like valgrind.
Larger audience, while Windows might have a huge platform share, the small communities of Linux and Windows are starving for games. And there's much less competition
Working with an existing rendering library is going to make things easier anyway, why not choose one which lets you easily target more platforms, Ogre3D for example.

Of course there is work involved, but I believe there's also a vast, largely untapped potential.
I'll also note that I agree with previous answers, targeting many platforms with your first application might be a stretch, but I'd suggest keeping it in mind anyway.
Answer:
Should beginning/indi game developers target multiple platforms initially?

For a beginner, I would suggest no. A beginner wouldn't have any idea what is and is not cross-platform.
Worst case scenario is you implement something that you thought was cross-platform. Weeks later when you compile on other platforms, you find out that it was broken. You'll either ignore it (gonna get the game working) or go back and revisit that code.

Why shouldn't we all write iPhone, Windows, or Browser games?

Complexity increases fast. For every platform you wish to support, you'll have to create one additional code path.


How do I host my website with another web hosting provider which is not the provider I registered domain name with?

Question: Recently I registered for a domain name and bought it. I had failed to check their hosting plans first :(. They charge a lot for hosting a website. I am thinking of hosting it under some free web hosting provider. How do I host my website with another web hosting provider which is not the provider I registered the domain with?
Answer: You just need to change the DNS settings for your name through the company you registered it with.  This process is slightly different for each registrar but it's not difficult to do.  You could also transfer the name to whoever you decide to do hosting with if they provide that service.
Hopefully the picture below gives you at least an idea of what to look for.
Comment: I checked for name server options, but it says "Any changes in our default name servers / dns settings may interrupt services associated with your domain."
Comment: @sriram You probably want to keep using the DNS server with the company you registered the name with.  What you want to do is change/add a host record so that it points to the IP of where your website is actually hosted.
Comment: found this while googleing http://ask-leo.com/how_do_i_automatically_redirect_one_web_page_to_another.html , but its a bit confusing on the DNS, records and types.
Comment: @sriram That link isn't exactly what you want.  Most of that content involves redirects that have nothing to do with setting up your DNS.  Who did you purchase the name through?
Comment: I purchased at hostindia.net
Comment: @sriram And did you already find and purchase web hosting also?
Comment: @pete No, I only registered a domain name. I am thinking of hosting at www.000webhost.com. They give 1.5GB storage + 100GB transfer per month for free, while hostindia.net charges like $11
Comment: @sriram OK, well, whenever you sign up they should give some directions and in those directions you should have an IP address.  You need to login to your control panel at hostindia.net and create or edit the host record to point to that IP.
Answer: As Pete said, just change the nameserver records to the new host. I bought a domain name with 1&1, but found $25/yr hosting at A Small Orange, so I changed my nameservers from ns1.1and1.com, etc to ns1.asmallorange.com, etc. It works differently for every domain, but the basic steps are the same. They do say that changes may interrupt their services, but you don't want their services. You want to map your domain name to a new host and use their services instead. If it doesn't work out, you can always revert to the original nameserver settings and original host.
You could also use CNAME settings to map your domain to another host, but I don't know as much about that. However you do it, it might take 48 hours, but be patient and your new host should be recognized and your website up and running.
Answer: You can transfer your hosting services from one provider to another. I have followed some simple steps while transferring my services from Godaddy to Bigrock

Create a Backup of Your Website Data
The next step here is the domain registration company to go about changing the information from your old DNS information to the new DNS system. Typically, this process takes about 24 to 72 hours that may get further extended depending upon the responsiveness of the registrar.
Initiate Uploading of Files to the New Server
Comment: -1: You didn't answer the question. They want to transfer use hosting with separate provider as domain name.


CAS Server that supports Facebook/Twitter authentication via OAuth

Question: I'm looking for a CAS server which supports Facebook/Twitter authentication via OAuth for Single-Sign-On. I've checked JASIG-CAS server but it doesn't look support them. My java web app is based on Spring Security 3 and other external PHP apps. Does it exist a CAS server with Facebook/Twitter support? Or an extension (or sample code) for this support on JASIG?
Comment: At which point specifically do you have the question?
Answer: Jasig CAS 3.5 will hopefully provide you with oauth authentication. It is not yet available as of writing this answer. But you can check out the release candidate of version 3.5.
Have a look here:
https://wiki.jasig.org/display/CASUM/OAuth+client+support
The source for 3.5 RC1 is available here:
https://github.com/Jasig/cas/
If your idea of integration of facebook twitter logins to cas is all about aggregation of various logins to one centralized login service, then this should be the right thing to look at.
Answer: You generally wouldn't ask Facebook/Twitter to pass authentication assertions to CAS but instead pass them directly to your application. Spring security supports OpenId and OAuth so this is relatively easy. You could then use CAS alongside Facebook and Twitter.


Is it possible to add credit to an account from a credit/debit/not a gift card?

Question: So I play this game on my iPod, Love Live: School Idol Festival. Within this game you can buy currency called love gems. I want to buy 50 of them, but need to add $10 more credit to my account to do it. I don't want to spend around $30 from the credit/debit/not a gift card. I already have $20 worth of credit on my account. It's just the $10 more I need. Is it possible to put $10 of credit into my account from a credit/debit/not a gift card? I've looked but the cheapest App Store card I can find is $25. I don't need $25. And I don't want to spend $15 unnecessarily. Or if I buy the gems can I charge the remaining to said credit/debit/not a gift card? It's hooked up to a PayPal account, could I add $10 through that? Please help me for I am deep in idol hell and am on a time limit as to when I can figure this out for what I want to spend the gems on if/when I buy them.
Comment: Does it not use the first $20 of credit then ask for $10 more?
Answer: Here's what you can do: you can have a gift card credit on your account as well as a linked credit card. Here's what you can't do: you can't only add $10 from a credit card to your iTunes account. But if you have a credit on your account now, and you link a credit card to your account, it will use all the remaining credit from the gift card first, then charge the remaining amount to your credit card.
Answer: I use the Wallet/Passbook to add funds to my account at Apple Retail stores. They take all sorts of payment there, but you'd need to go to the store physically to pay.
I'm not aware of a way to load the account yourself using the iOS app or online. There also are $15 and $10 cards you can buy online - you need to trust that the vendor will email you a valid code - but I've not had issues when I use a major retailer like Target to make an online purchase.
You could also send a friend to the Apple Store to buy a blank card with the custom amount you desire - they have blank cards for that purpose.
Online sales from Apple doesn't seem to cary the custom amount cards so you've got lots of options to not over spend if you can take advantage of one of them.


Pain in the heel after a hike

Question: So, I just went hiking, testing out a pretty new pair of shoes. The test trail was about 6 miles round trip. I started to notice on the way back that the back of my heel was a bit uncomfortable, like it had been rubbing for a while. Is there anything I can do short of getting a new pair of shoes to help with this problem?
Answer: What you describe sounds like the early symptoms of blisters, a few things you could try are:

Are your shoes laced too tightly? If they are too tight over the instep, movement in your foot as you walk will increase friction at the heal.
Are your shoes laced too loosely? They should be tight enough so your feet do not slip up and cause friction as you walk (but not too tight per point 1).
Wear two pairs of socks. A light pair of inner socks may alleviate the problem so the friction occurs between the layers of socks rather than on your skin.
Avoid cotton socks. Cotton tends to stay damp once it is wet (either due to the weather or persperation) and wet socks will exacerbate any friction.
Wear good quality socks designed for hiking. They will be made from material that dries easily and wicks away moisture. They should also be designed to minimise friction.
Comment: I read from this, get new socks. Guess I'll have to do that...
Comment: @PearsonArtPhoto also, as new shoes tend to reform a bit to your fit during their break in period, it may be worthwhile to stop every few miles to untie and retie the shoe laces to adjust for that deformation.  But good socks are definitely a good idea if you don't have some already, although pretty much any "sports" socks should do a decent job for short (i.e. day) hikes.
Answer: As well as the other answers, I notice you said they were new shoes you were hiking in - it isn't uncommon for these to be more likely to rub and potentially cause blisters until they're properly broken in. Follow the other advice (especially about socks) with blisters because that can hugely help - but in addition to this you may also want to try wearing them for shorter hikes / walks, little and often, until they're broken in a bit more. You might be surprised at how much this can help!
Answer: Depending on the type of pain, this may be plantar fasciitis. If it's more of a burning, that developed slowly and started to get worse while hiking, it may be a hot spot which you should take care of as it can cause blisters.

Pain in the heel after a hike


How was the Apostle Paul a Debtor to the Greeks?

Question: Romans 1:14

I am debtor both to the Greeks, and to the Barbarians; both to the
  wise, and to the unwise.

In what sense was Paul a debtor to these groups of people? I can't find any context in the immediate verses around this passage.
Answer: For what it's worth, my observation of the context is that the debt is derived from his call to preach the gospel (see verses 11-13 & verses 15-17) to the groups listed. Particularly note in verse 1 how Paul views himself as a servant of Christ (some versions 'bondservant'). His debt was primarily to Christ who had purchased the apostle's life with the blood shed at the cross, and secondarily to the designated groups that Paul had been assigned to serve through his apostolic calling.  It can often be helpful with this sort of issue to check out a few different translations or commentaries as that can reveal some of the underlying complexity of the original language even if you have no or little knowledge of it - for instance:

Both to Greeks and to barbarians (to the cultured and to the uncultured),
  both to the wise and the foolish, I have an obligation to discharge and
  a duty to perform and a debt to pay. - Romans 1:14 (Amplified Bible)

Perhaps the first two variant meanings (an obligation to discharge and a duty to perform) are a little less confusing?
Comment: The NIV also understands "debtor" as meaning "obligation".  I think the debt being referred to is stated in the next verse "So, as much as in me is, I am ready to preach the gospel to you that are at Rome also."  He's saying he has a "debt" to preach the gospel to everyone.
Comment: @davidbrainerd your comment is really an answer so If you answered the question why not vote on it?
Comment: @bruisedreed I checked out Hermenuetics SE and you're probably right!
Comment: @CecilBeckum Please stop with the voting comments, they are noise.
Comment: +1 - It is unexplained why good answers all over this site languish with zero votes or less
Answer: There is nothing wrong with the other answers I only mention that this phrase perfectly aligns with the Roman world and Paul's sense of debt to give them the gospel, as Hodge points out:

The Romans, whose city was called "an epitome of the world," belonged exclusively neither to the one class nor to the other. Some were wise and some unwise, some Greeks and some barbarians. (Hodge, C. (1882). A commentary on the Epistle to the Romans,pp. 39–40)

Once good description of how much Paul really truly was a debtor on not just a random feeling he had is found here:

When Moses had received the tables written with the finger of God, and the pattern of the Tabernacle for Israel, he was bound, he was a debtor, both to God and to Israel, to deliver those tables and that pattern, as given to him by God. To Paul, the risen, glorified Christ Himself had given the gospel by especial "revelation" (Gal. 1:11, 12); and Paul, as we know, was especially to go to the Gentiles, (as Peter, James and John were to go to the circumcision). Just as definitely as Moses received the Law for Israel, so Paul received the gospel for us, and he was a debtor, both to God and to us, till he had that gospel committed to all. (Newell, W. R. (n.d.). Romans Verse-by-Verse ,p. 12)
Answer: Paul was convinced, that Jesus had called him specifically to carry the Gospel to the Gentile Nations:
All Scripture is quoted from the New Revised King James translation.

Acts 9:15 and 16 But Yahushua said unto him, Go thy way: for he is a chosen vessel unto me, to bear my name before the Gentiles, and kings, and the children of Israel: For I will shew him how great things he must suffer for my name's sake.

Paul would therefore accept that because Jesus  wanted to include the Gentiles, they were the reason Jesus called him. Therefore his salvation was owing to the Gentile world.
It seems to me, that if this was his motive for preaching the Gospel to the Gentiles, that it was a powerful motive.
Comment: +1 - It is unexplained why good answers all over this site languish with zero votes or less.
Answer: Since Jesus came to save all mankind, both Jews and non-Jews (Paul is so emphatic and frequent in stating that, especially in Romans, that I will not bother your eyes with superfluous quotes), and since He willed to affect this salvation through giving His apostles His grace of preaching and converting both Jews and non-Jews, then Paul, an apostle who has received this divine grace is, in virtue of this reception, under the obligation to dispense this grace and co-work with this grace with a purpose of converting all nations, Greeks included. In this sense, Paul is a debtor of Greeks, together with all the rest whom he preached.


Why do we do hosha'nos and hakafos counterclockwise?

Question: I have attended services in a number of different Ashkenazic synagogues on Sukos and Sh'mini Atzeres/Simchas Tora. When going around the bima for hosha'nos on Sukos, and, in most cases, when doing so for hakafos on Sh'mini Atzeres/Simchas Tora, people went counterclockwise (when viewed from above). Why counterclockwise?
Comment: I assume that is as the Kohen around the Mizbeach when he is in front of the Mizbeach he turns right and begins to go along the wall,  this is always counterclockwise.
Comment: כל פינות שאתה פונה לא יהיו אלא דרך ימין
Answer: Mishna Berura 660:1:3 says that when the Sefer Torah is on the Bimah those on the Mizrach (eastern wall) turn around to face the Torah their right side is now facing Tzafon (north) therfore they start in that direction.
Comment: ... and by extension, if everyone faces the center of the shul and then turns right, they'll be going counter-clockwise.
Comment: +1; many thanks. That's _hosha'nos_. I guess _hakafos_ (_Sh'mini Atzeres/Simchas Tora_) probably derived from there by force of habit or something?
Answer: Everything done in a Beit Kenesset is modeled on the procedures as they were done in the Temple, "HaMikdash", in Jerusalem. That is why a synagogue is known as "Mikdash Me'at", a small Temple (Yechezkel 11:16, Megillah 29a in the name of Rabbi Yitzchok).
In the Temple, when the first Kohen would enter in the morning to unlock the doors, they would turn to the right and proceed to go counter-clockwise around to unlock everything. All of this is based on the concept that the right side, "Kav HaYamin", is considered the side of kindness, "chesed".
Going to the left side, "Kav HaSmole" and proceeding clockwise is associated with judgement, "Din". This is the same reason why when ascending to the Torah for an aliyah, you approach from the right normally and depart from the left, counterclockwise motion. When someone approaches for an aliyah from the left, it is an indication that they are a mourner.
During Sukkot and on Hoshannah Rabbah in particular, we are drawing "Chesed" into the world through our avodah. That is the main idea behind the judgement pertaining to water that takes place at that time and the idea of "Simchat Beit HaSho'evah", the joy of drawing water from the wellspring. We are sweetening the judgements that are finally sealed and sent for execution on Hoshannah Rabbah. And therefore, we go to the right and counterclockwise.
Comment: @mevaqesh His source "Yechezkel 11:16, Megillah 29a in the name of Rabbi Yitzchok" is just a source that a synagogue is known as a "Mikdash Me'at", not, as he disingenuously claims, a source for "That is why a synagogue is..." He has brought no source for his reason behind the name, while making it appear as if he did.
Comment: `Everything done in a Beit Kenesset is modeled on the procedures as they were done in the Temple,` source?
Comment: "In the Temple, when the first Kohen would enter in the morning to unlock the doors, they would turn to the right and proceed to go counter-clockwise around to unlock everything." Citation needed. Iirc _Tamid_ says that after opening the first door, _kohanim_ would enter via it and go around in __both__ directions (split into two groups), meeting up at the _lishkas ose chavitin_.
Answer: We always do things from left to right as the right is superior in the Torah.
As a matter of fact where I daven (pray) we are also makpid (מקפיד) to do boi besholem (באו בשלום) in lecho dodi (לכה דודי) counter clockwise.