Other than speed, is there a reason that a 10W iPad charger shouldn't charge a new MacBook Pro 2016?

Question: Are there any reasons not to use a 10w ipad charger with a USB->USB-C cable to charge a new MacBook Pro 2016? Have the one charger that came with MacBook but would like to be able to plug in at office, home on road, etc. with other chargers. Thx.
Answer: A 10 watt iPad charger will not charge a MacBook Pro because the MacBook Pro will only charge from a USB power supply that supports "USB Power Delivery" or USB-PD.  Apple's website states as such.  Even then there may be other conditions that need to be met, such as voltage and current supplied.
No USB power brick under 18 watts, at least none that I am aware of, supports USB-PD.  A USB power brick that doesn't support USB-PD might supply power, which will slow the discharge from the battery, but it will not add charge to the battery.  Connecting a 12 watt USB power brick to my MacBook Pro will show in System Information as supplying power (at least that's what it looks like to me) but it does not show as charging the battery.
During a power outage I was able to run my MacBook Pro from a 27 watt USB-C charger that was plugged into a portable power pack.  With some rather lightweight web surfing I didn't see the MacBook battery run down.  This same 27 watt charger was able to charge the battery while the laptop (and I) slept.
Officially that's the story, that a MacBook will only charge from a USB-PD power supply.  Unofficially, I have read that people have had mixed results using non-USB-PD chargers to charge MacBooks. Personally I have not been curious or desperate enough to run this experiment myself.  My guess is that for this to work the laptop would have to be using less power than the power supply so that there is enough power left over to put in the battery.  That means the laptop would likely have to be powered off or asleep.
If you are looking for a travel charger for your MacBook Pro then I'd suggest getting nothing smaller than 27 watts.  Anything smaller is unlikely to charge the battery, and if it does it will charge quite slowly.
Comment: I can confirm that my MacBook Air operates but does not charge without PD, even if left turned off.
Answer: A 10W iPad charger should in theory work and you would be correct that it would be a slow charge.   Well, to be accurate, it would be a horribly slow charge - you are getting a charger that is 1/6th (17%) of what is required (61W).
Will there be a problem?  No.
Will it charge?  Slowly.  Molasses in January slowly. From Apple's web site:

Your Mac will charge from USB-C power adapters not manufactured by
  Apple if they adhere to the USB Power Delivery specification.

Assuming you are using a genuine Apple iPad charger, it should charge since Apple charges adhere to the spec.
Comment: I would take my 61W charger and not the iPad charger.  The 61W is compatible with both and will not damage your iPad .  The iPad will only draw what it needs.   A good rule of thumb is that your charger must be >= to the device draw, not the other way around.
Comment: I just want to add that if you end up using the iPad charger to do this on a regular basis, in the long-term you will damage it (i.e. reduce it's life). Also, I would strongly recommend not doing this while the MBP is running. However, the rule of thumb used by @Allan is 100% spot on and I would be carrying the MBP charger around instead.
Comment: Thx. It won't be my main charger...but I would like to use when the standard MacBook charger isn't with me.
Comment: ok. Thx for the advice. Are there any 3rd party chargers you can recommend? I would like to have 2 or 3 chargers available but the Apple one is pretty pricey.
Comment: At present, there are no (that I know of) USB-C type chargers with >61W of power.  The best one that I have seen is the [Anker USB 30W charger](https://goo.gl/xUAYTq)  It will charge the MacBook, but not the MBP.  Chances are they will come up with a charger capable of handling the Pro (61W or 87W).  When I find one, I will update the answer.
Comment: @Sizzle try the Aukey Omnia series. They're not too pricey and extremely portable. They come in 61W and 100W variants.


How to name modes of non-major scales?

Question: What is the common way to name modes of, say, the harmonic minor scale? Can one say "D harmonic minor Dorian" and be understood to mean the second mode?
Comment: Found a duplicate: http://music.stackexchange.com/q/46114/27532
Answer: "D harmonic minor dorian" does not make sense, because "dorian" doesn't mean just a second mode of some scale, but it has a very concrete meaning, namely a scale with a minor third and a major sixth.
The names for the modes of harmonic minor are not as standardized as the names for the modes of the major scale, but you would often see the following names:

I.   Harmonic minor
II.  Locrian #6
III. Ionian #5
IV.  Dorian #4
V.   Phrygian Dominant (= phrygian #3)
VI.  Lydian #2
VII. Mixolydian #1 (Ultralocrian, Altered Dominant bb7)

As you can see, most names are derived from names of major modes, e.g., dorian #4 simply is a dorian scale with a raised 4. The name of the seventh mode appears to be the least standardized. Following the logic of the other names, it should be mixolydian #1, but most people tend to not recognize the relationship with mixolydian because in this case it is the root which is raised. I've also seen superlocrian for the seventh mode of harmonic minor, but this name is problematic, because it is also used for the seventh mode of melodic minor (among others).
For the names of the modes of melodic minor you have even more theoretical possibilities because the melodic minor scale can be viewed either as a major scale with a flatted third, or as a dorian scale with a raised seventh:

I.   Melodic minor
II.  Phrygian #6                  |  Dorian b2
III. Lydian #5 = Lydian Augmented | [Phrygian b1; not used]
IV.  Mixolydian #4 (#11)          |  Lydian b7 = Lydian Dominant
V.  [Aeolian #3; not used]        |  Mixolydian b6
VI.  Locrian #2 (♮2)              |  Aeolian b5
VII.[Ionian #1; not used]         | [Locrian b4; not used]
     Altered Scale, Superlocrian

As indicated above, some theoretically correct names are simply not used, especially the ones where the 1 (root) is raised or lowered. Furthermore, the seventh mode has a special name because, at least in Jazz, it is used frequently. Its most common name is "Altered Scale" because it contains all alterations over a dominant seventh chord (#5=b13, b9, #9 #11=b5).
Comment: Thanks. So if I understand the "logic" behind this naming convention, it is to find the closest major mode, where distance is measured in number of accidentals. (I'm trying to write an algorithm for this fwiw)
Comment: @infojunkie: Yes, and this works in principle with all (common) heptatonic scales.
Answer: The most unambiguous way to refer to these modes is a little verbose, but is common in the academic world when discussing rock/pop/hip-hop music especially. You just number the modes, and then say "xth mode of harmonic minor on tonic" or "yth mode of melodic minor on tonic."  Alternatively, you could say "nth harmonic minor mode on tonic. If a piece had G as tonic and followed the standard harmonic minor scale, we just say "G harmonic minor" (not "first mode of harmonic minor on G"), but if a piece has G as tonic but the notes of C harmonic minor, we would say "fifth harmonic minor mode on G." However, this particular mode is so commonly known as the Phrygian dominant, we often just use that. The longer locution is more necessary for less common harmonic minor modes and for the melodic minor modes.
Again, it's an admittedly awkward phrasing, but it does away with ambiguity and less-agreed-upon naming conventions. There are also some legacy terms that most now consider offensive (such as anything involving the word "gypsy"), which this system avoids as well.
Comment: Are we not supposed to say 'gypsy jazz' any more?!
Comment: @Tim As is generally the case with an issue like this, not all members of the community agree, but many Romani people find the term offensive. I try to err on the side of caution.
Comment: Thanks. This "rational" naming convention is certainly a great complement to the more packed convention based on closest major modes.
Answer: I believe the different mode names are only relevant to major scales. In a harmonic scale(a minor), it doesn't work. Instead, you change the degree of the scale to suit your harmony by starting at whatever note you want to suit what sound you wish to achieve.
Your harmony is there to complete the melody and is not as "rigid" as a major scales.
Scales you learn are a basis for explorations. You can use them in any way you want. There are dozens and dozens of them, all derived from a basic major.
Hope that helps
Bill
Comment: The basic names - dorian, mixolydian, et al, need to have subtle changes which reflect the single changed note when dealing with minor scales/notes/modes. Thus, dorian, with its spaces between notes which make it dorian, needs to be called dorian b2, for that's just what it is - the standard dorian mode notes except the 2 is flattened. Lydian #5 - same as lydian, but, you've guessed it, the 5 is sharp.

How to name modes of non-major scales?


Android: Does any app use inline editing?

Question: I have a list with items. I want to know, if I can edit the name of the item inline. Just tap and rename the item.
Is this right to make it in android? I don´t see any app that do this...
thanks!
Comment: Generally I think if this items are in a ListView tapping the item would take the user to a new screen that would allow deeper editing. This new screen could just be a dialog that popups up and allows editing the name of the item though. This is also how I'd expect things to work on iOS, but if you have an example of the behavior on a different platform that might help people to come up with suggestions.
Comment: I don´t have an example, but I´m particularly interesting in knowing how the android users would except that...
Answer: From the interaction point of view
People will be touching the UI a lot: long press, swipe, drag, double touch, etc.  It can be frustrating to users if the renaming feature is constantly initiated because the user accidentally touched the screen.
Comment: Thanks! I didn´t think that, I that´s right! It would be so frustrating...thanks for your help!
Answer: I would make an edit icon appear when pressing and holding a list item for a while - this is always the first thing I try when it comes to edit stuff. By using an edit icon (or menu) appear - the user won't be transferred into a new location which can be confusing.
The Facebook app is using a swipe from right to left to make the Edit menu appear. It took me a long time before I found that one out - not sure why they went that road.
As a backup - I would put edit menu list item under the menu that opens when pressing the Android device's menu button. That's where I (and probably a lot of other users) secondly checks for functions.


Two textures one output

Question: I try to use two texture in the same material.This material is for a jacket, and one texture containing the default leather material texture, and the other someting like a decorative stripes. My question is, how to blend the two textures together in the same output. I tried the "Mix" node with not too much success.
Answer: You can try to mix them together with a Color > MixRGB node and find the right mode (here Multiply). Don't forget to put a Diffuse node after the MixRGB.
Answer: I'm guessing you are using the textures for one shader so:
Use a mask by painting (or placing) a black and white texture in factor socket mix rgb node.

if the details texture are on a transparent png, use the alpha output of the png image as your mask and connect the alpha to factor of mix rgb. if it shows wrong try inverting the mask color or swapping the color1 with color2.

Two textures one output


Is there a tool which will resize photos based on level of actual detail in the original?

Question: As part of my organisation workflow I like to scale down images where the quality of the photo is not making the most of the resolution (due to camera shake, low light graininess, or whatever). Is there any tool to help me achieve this?
Comment: Are you asking if there is a tool that will allow you to resize an image? Or one that will automatically resize it to a variable size based on the quality of the contents of the photo?
Comment: Based on some measurement of the image quality.
Comment: Are you talking about before or after post-processing?
Comment: Anything really that could work on JPGs. ATM post processing for me involves putting the snaps in the right folder...
Answer: You could use python and one of a number of libraries, (such as SciPy/Numpy), to get a measure of the noise in the image as shown in the answer to this Stack Overflow question.  Some of the same libraries and also perform image scaling and denoise e.g. SciKit Image has both denoise and scale image functions.  You could also take a look at the python integration with the OpenCV project tools.
Once you have a script that works reasonably reliably you can use the marvelous os.walk function to work down through a directory tree finding files and processing them unattended.
One important word of advice - Back Everything Up First! - A writable DVD costs pennies and can store 4.7 Gigabytes - that is a lot of images - a terabyte portable drive is under £70 here and is even quicker to use.  All the above tools are Free - both Libre and FOSS but if you replace the only copy of an image with one that you have damaged then the price could be high.


"Send Test" buttons greyed out inactive

Question: When "SEND TEST" buttons are greyed out there is no notification as to what is missing from required fields to be NOT NULL. By default if "Opt-Out" token is not included in the message the "Opt-Out" response is left NULL but is still a required field that cannot be left empty. Choosing the only default brings all the buttons active. Please advise?
Answer:
There shouldn't be any connection between the "Opt-Out"/"Unsubscribe" token and the field "Responses: Opt-Out Message". Both are required.
If the "Opt-Out" token (or "Unsubscribe" token) is missing, then you should get a very loud error message. (The token is generally provided as part of a header, footer, or message template, so that you don't have to put it in explicitly.)
The field "Responses: Opt-Out Message" should be filled in by default. If it's not, then perhaps someone removed the default. Try navigating to "Mailings => Headers, Footers, and Automated Messages". Edit one of the "OptOut" messages and set it as default.
Comment: CiviCRM will allow it to pass with one *or* the other or both tokens. And, a little "Duh!" on the default Opt-Out message. You are correct. And, thank you for the patch. Great work!
Answer: I found a couple more situations that the greyed out button can appear which may be less than obvious

if there is no Resubscribe Msg set on the Response tab (no alert is currently provided
if you put in a Subject, but then decide to switch to using a Template that has no Subject then the one you added gets wiped

"Send Test" buttons greyed out inactive


Rule to create a new view when a node is created

Question: I have an event registration site that uses the Entity Registration module for its registration forms. There is also an admin section that uses the Views Data Export module to export all of the registration details.
The trouble is there is no views field (like there is with Webform) that says get all fields from this registration.
As the site hosts multiple events throughout the year, it means that I have to create a new view for each event.
Is there a way to use rules to create a new view or (preferably) view display when saving a node of the Event type.
Answer: I think a better solution would be to use a single view with a contextual filter here.
I don't have experience with the Entity Registration module but since it's entity based it should have an Registration id contextual parameter which you can give a default from the url.


DNA match higher with a younger generation of the family

Question: I have a 107 cM match with Eli.  His mother is Lily and Lily's brother is Henry.  Henry's son is Henry Jr and his grandson is Kevin.  I have a 235 cM match with Kevin.  Kevin is one generation younger than Eli.  I don't understand why there is a larger cM for Kevin over Eli.  (I used fake names.)
Comment: Are Eli, Lily, Henry, Henry Jr and Kevin their real names?  See https://genealogy.meta.stackexchange.com/questions/3337
Comment: no, fake names but cM is correct.
Answer: I am going to hypothesize that:

Lily and her brother Henry inherited 235cM from their parents.
Eli may have only inherited 107cM (of the original 235cM) from his mother Lily.  He did not get the remainder by chance.
Henry Jr may have inherited all 235cM from his father Henry.
Kevin may have inherited all 235cM from his father Henry Jr.

By the above hypothesis, it is possible that Kevin, even being a generation younger than Eli could nevertheless share more DNA with you than Eli does.
You could test my hypothesis if Lily, Henry and Henry Jr were to test.  You would not expect all the numbers to be right but you would expect children to always share less cM (or the same) with you than their parents.
Comment: Understanding cMs is new to me.  Hopefully your hypothesis will be an example I can  learn from.  Testing of others is not likely.  From my mother, brothers, and cousins the cM number seemed to make sense, so this was confusing me.
Answer: Whenever you look at a specific relationship in DNA terms, there is a range of cM associated with it.  The cM range for any given relationship will overlap with, usually, multiple other possible relationships.
We all start with 6800 cM.  If you compare yourself to a test of yourself, or your identical twin, it will be more or less 6800 cm.  You and your child will have a match of around 3400 cM.  After that, it can get dicey.
Your child has approximately half her/his DNA from you and half from her/his father.  But that half that is from you...how much is from your mom and how much from your dad?  The average will be 25% each.  Meaning everything divides neatly in half.  But the reality is always a range.  There's no way to predict which side of any given DNA strand will be the one passed down to a child.
Eli and Henry Jr. are first cousins and they share a single set of grandparents.  In theory, they should each have 25% of their DNA from each of those shared grandparents.  This means around 1700 cM inherited from any given grandparent (numbers are rounded).  In reality, the range of cM from each grandparent is 1156-2311 cM.  Add to that the fact that each grandchild will inherit different DNA segments from each grandparent, not just different amounts of total cM.
Eli's first cousin once removed, Kevin, may have, as PolyGeo points out, nearly all of the DNA his dad had from one or more of his paternal grandparents.  Or he may have inherited very little.
Both Eli and Kevin will be within the cM ranges for the relationship they have with you.  Use this information to narrow down what relationship you have to this family.  Because of the disparate numbers, you have an opportunity to narrow down the possibilities more than most people do.
There are also other explanations.
You might match Kevin through both his mother and his father.  This is not uncommon in general but, if you all belong to an endogamous ethnic group (any group that tends to marry people of that group, even if they are not known family, for example, Jews, Hawaiians, Mennonites, Colonial Americans, etc), then it's more common to match over multiple lines than just one line.
It is also possible that Eli's and Kevin's family has some secrets, but that is not the conclusion I would jump to.  Everything you describe is perfectly normal and easy to explain.
Answer: There are not many pairs of relationships where these cM levels would fit in the known ranges. While there are several cousin relationships (some fairly distant) which ranges would include Eli's 107 cM, there are not very many that would allow a more distant relationship at Kevin's level.  One possibility might be Eli - 2C (46-515 cM) and Kevin - 2C1R (0-316 cM). I'm not suggesting that's the actual relationship, but you should probably be looking for something like that.
As previously noted, matches with other cousins on both sides of their families will provide additional clues. One additional data point that would be useful to know is the match level between Eli and Kevin, which might either suggest or rule out some of the zebras.


How can I locate a spider spawner?

Question: I'm trying to find spider spawners to gain experience on an SMP server. I've seen other players that have found 4 spawners near each other. Is there a trick to finding one or more?
Answer: I'm assuming you mean cave spider spawners. The best way to find them is to search abandoned mine shafts. The abandoned mine shafts are generally tunnels 3 blocks high and 3 blocks wide and have wood blocks and fences creating frames around tunnel. They have minecart tracks, cobwebs and random chests placed in them.
Abandoned Mine Shafts - Minecraft Wiki
Also check out What's the best way to find Abandoned Mine Shafts?
Most notably is that you will find areas filled with cobwebs. This area has cave spider spawners. Sometimes you'll find spawners close together but finding 4 in the same area is pretty rare.
Comment: It should be noted that the easiest way to find Abandoned Mine Shafts is from Ravines. I have yet to see a Ravine that doesn't have a AMS cutting through it.
Answer: If you search abandoned mines, usually spider spawners have a massive amount of cobwebs around the area.
Comment: Note that mineshafts contain *cave* spider spawners, which are poisonous on some difficulty levels.
Answer: Get a mapper, such as minutor, and you will be able to load up your world and easily locate spawners. You will not be able to easily determine their type though as far as I'm aware.
Although slightly outdated, the answers to this question should help too.
Answer: Try to find a dungeon, which may be located in a cave or abandoned mineshaft. If you don't know what I mean, this is an example:

The dungeon has cobble and mossy stone blocks around it, so it's easy the recognize.   It normally has chests of loot. In the middle is the spawner, it's easy to know what it spawns depending on what mob is spinning inside.
If you actually are looking for cave spiders, they're found in abandoned mineshafts. They have wooden fence poles with planks on top, which are easy to recognize, and you'll also find cobwebs too.
Answer: Take a water bucket with you. It will help a lot to break cobwebs.
If you play solo, you can use an "x-ray" texture pack to see through blocks. It is also helpful if you can install a minimap mod so that when you find a spawner, you can put a waypoint on it and then remove the texture pack.
Also like others said, you can find cave spider spawner easily in a Mineshaft (like picture # 2 of Jim's answer). They always have many cobwebs around, and it's not rare to see 2 spawners near each other.
For regular spider spawners, you must focus on Dungeons (square room with mossy cobble, like the picture 1 of Jim's answer). They have a spider, skeleton or zombie spawner inside.
To make a cave spider farm, make a dark room around the spider spawner then leave a tiny sideways hole (ex. Using glass and fence) to kill them. But don't get too close or the spider may attack you trough the wall.
Answer: You can make a copy of your world then in your copy go in creative mode and use the /locate feature to find an abandoned mineshaft I used this in my single player world an I amazingly found a penta spawner and a quad spawner somewhere else in the mineshaft. I think they are not that rare in mineshafts and if you don't find a good spawner you can go like 500 blocks in another direction and use the locate feature again to try and find another mineshaft.

How can I locate a spider spawner?


What is this glassware between flask and condenser to collect liquid?

Question: I've been trying to identify this piece of glassware for ages now. I've been combing the internet and can't seem find anything similar. It looks like some kind of adapter/collecter/trap that sits on the pot and the condenser goes on top.
Comment: The picture looks like an upscaled screenshot of a video hosted on YouTube. Would you mind sharing the URL? So far from the look of it I'd say it's a custom-made piece of glassware, but the context might help.
Comment: thank you.  i will find the video and post a link of it. regards, james
Comment: It is a collector indeed. For small amount of distilled target
Answer: This glassware is used to separate /remove the light phase from a biphasic (immiscible) liquid mixture.  This can be used primarily to enhance liquid-liquid extraction from the light phase to the denser phase. As a mixed distillate collects,  the denser phase will eventually siphon back through the side-arm to the flask below and the light phase remains in the collector.


Raspberry Pi 3 Bluetooth

Question: The Raspberry Pi 3 model B has inbuilt Bluetooth, using BlueZ stack. I want to know in which language the stack is written, Python or C?
Comment: As Adam observes different components of a software stack can be implemented in different languages, but with most OS's including linux, for anything to do with hardware the lowest level(s) are going to be in C and asm.
Answer: The source code is written in C. Look at the BlueZ download site, and follow the links to the source code on github

Source code is also available in the GIT repositories at kernel.org.

The GIT repositories on kernel.org contain the source files. Taking one at random, i.e., a/src/gatt-database.c b/src/gatt-database.c, you can see that it is written in C.
Answer: Like @greenonline says, Bluez is written in C, but the newer code base allows for interactions with Bluez through their DBus API. Much of the example code is written in Python and is a bit more accessible than the C code.
If you look in the test/ folder of the GIT Repo lots of the examples are written in Python (The executable files don't have the .py extension, but are just python scripts). Overall documentation is very sparse, but I've found that folder is a decent starting place for interacting with Bluez. Just keep in mind that you will need to run bluetoothd with the -E to use the DBus API as it's still experimental, you will also need to compile with the experimental code enabled.
Answer: Linux and GNU are both open source.
This means that the source code is freely available.
Go to the Raspbian repository and look at the source code for any package in which you are interested.

Raspberry Pi 3 Bluetooth


Store "schemas" to build custom forms using postgres and rails

Question: I'm building a site using rails that will have 1000s of custom forms. Before we build a form builder user interface, we'll be essentially creating and storing the "schema" manually and using the "schema" to build the form.
I had originally posted this question to help figure out how to create the form from a YAML file: Create a form in rails by reading a yaml file
But after doing some research, it seems like it would be better to store the "schema" in our db and now I'm wondering what the best way is to do that. It seems like there's a "jsonb" type for postgres dbs that I could use - is that better than storing the "schema" as YAML data? And would I use the "bytea" type for this type of data? Are there any thoughts on if it would be better to use JSON or YAML? Also, do I just put the contents of the schema in the db or is there a way to just store a file?
Thanks!
Answer: I would use the native Postgres JSON type.
http://www.postgresql.org/docs/devel/static/datatype-json.html


Download one particular file from a large .zip file in Google Drive

Question: Lets say I have a large .zip file in Google Drive with multiple images. Now I wish to download one particular file from this .zip file without downloading the entire .zip file. Is that possible? I checked there are apps like zip extractor, not sure it works. I tried but it takes forever to download the file. You may understand that the .zip file is in GBs.
Answer: There's nothing built in to Google Drive for working with ZIP files. You would need to use a Google Drive add-on. I'm sure there are several.
Of course, if you sync to your PC with the Google Drive sync tool, unless you've excluded that folder, the ZIP file is already on your hard drive.


How to change the shadow color in Blender Cycles?

Question: I want to change the color of the shadow casting by a cube to green. While it's very easy to do it in Blender Internal (you select the lamp, go to the Lamp data header and change the shadow's color in the Shadow panel) in Cycles there're no such options. How to achieve it in Cycles?
Answer: With the Cycles renderer enabled select the cube, give it a new material and set the material nodes as pictured below. Use the Is Camera Ray of the Light Path node as a factor for mixing the Diffuse and Transparent nodes (Is Shadow Ray works good as well).

Change the Hue, Saturation and Value values of the Transparent shader to change the shadow's color, intensity and transparency.

Here's the animated test using the changes mentioned above:
Comment: Shadow ray is the proper way to do this as camera ray will color reflections as well which will be noticeable in more complex scenes.
Comment: This doesn't seem to work when the shadow is cast on a shadow catcher, is there a workaround for that?
Comment: This doesn't work with the self-cast shadows
Answer: An alternative way to do this is to make the light have different colors for direct and indirect rays:


On the buyside, when people quote a 'price' for a plain vanilla interest rate swap, does it include accrued interest?

Question: The valuation date falls in between coupon payment days on the swap, does the 'price' of a swap understood to include the accrued interest (interest from the previous payment date to the valuation date, as a fraction of the number of days in between) on both legs? Or is it only PV (only counting cashflows starting from the upcoming coupon payments) ?
Comment: Price for swaps is usually quoted clean (without accrued).
Answer: If you value an existing IRS then you value its official cashflows to their full extent, i.e. implicitly including accrued interest. When an IRS is 'torn up' (or 'bought out' or 'terminated') it is natural to expect discounted value of all of its cashflows.
When a new IRS is 'created' (or 'written' or 'executed') partway through a period it will contain one (or more) 'stub-period'. These are unnatural length periods which  settle to an interpolated rate representing the length of the coupon. Since new swaps are rarely created with a backwards start date this is implicitly without accrued interest.


Just bought a car, engine running hot, found pure water for coolant

Question: Just bought a 01 Galant 128k.  Engine seems to get hot quite a bit, approaching the red zone but has yet to overheat.  Found pure water in the coolant reservoir.  Will draining the water and replacing with a 50/50 glycol solution improve the heat loss through the radiator? Or might I have an issue with the water pump?
Comment: I agree it's a duplicate, and I agree you have an issue with the cooling system.
Comment: Also seemingly related, but with a somewhat different focus: [Clear water in coolant reservoir](https://mechanics.stackexchange.com/q/5979/7356)
Comment: The problem was buying a car that's running hot. Who knows what the seller was trying to hide.
Answer: Cooling replacement will not solve the problem. Water should handle it. The problem might be in Thermostat or Water pump. On water pump usually first goes bearings - getting rusty and wears out. It happens if you buy a car which haven't been driven for 2 years.. When the bearings are shaking, the impeller is touching the walls and grinds down until breaks. So you should hear a whining bearing noise. If you can see or reach the water pump pulley, you can give it a shake, should feel it through tensioned belt. If it is thermostat, it is easier to replace it than to test it. It is accessable on your car. But it also could be your cooling fan relay. Check if it turns on when the water temperature goes over 90°C or over the middle of a gauge. If it doesn't turn on, it can be thermostat or fan relay, because thermostat don't let the hot water in radiator so the relay don't know that it's hot...


Backing up my Bitcoin wallet

Question: I'm really new to Bitcoin (just started today) so forgive me if this question has been asked before but I can't seem to find an answer on Google. From what I understand, the Bitcoin program is capable of encrypting your wallet for you. So, can I safely encrypt the wallet (using bitcoin-qt) then move it to my Dropbox folder and then symlink it so the program will access the copy in my Dropbox. I don't really want to lose my wallet.
Comment: The only thing encrypted are the private keys.  Left unencrypted in the wallet.dat are the addresses and transactions.   If you want those not revealed should your DropBox get compromised, you'll want to use TrueCrypt or something else.
Answer: Yes, as long as you close the Bitcoin program first, you can copy the wallet.dat file anywhere you want to back it up. Just remember to keep it safe and use a password, and your Bitcoins will be safe. If you lose the wallet, you will lose the bitcoins you have in it forever (there is no option of recovery of lost bitcoins, unless you are talking about recovering lost files from your hard drive).
Comment: Erm, that wasn't what I meant. I meant enabling passcode encryption within Bitcoin-qt and then transferring the wallet.dat from application support (I use a mac) to my Dropbox folder. I then intended to use terminal to symlink it so that Bitcoin-qt will work off the dropbox copy.
Comment: Hmm, if you want to run your Bitcoin from the Dropbox folder, you can always start it with -datadir flag - https://en.bitcoin.it/wiki/Running_Bitcoin.
Comment: That also puts the blockchain there as well.  A symlink will allow you to put the wallet and nothing else in Dropbox.

Backing up my Bitcoin wallet


What are real strengths of association when using Pearson correlation?

Question: I have located a table that breaks downs Pearson's correlation values into 3 categories. See below:

My question is this. One could have a large positive correlation of 1 as well as a perfect correlation. Is this table valid?
Comment: What would it mean for this table (or another table like it) to be valid or invalid?
Comment: If someone says 'that water is very hot' and another says 'that water is very cool' is either necessarily valid or invalid? If the first person is trying to wash her hands while the second is trying to make tea, could that impact the likelihood of both being valid, compared to them both trying to make bread? .... [The point, in case I am being too obscure, is that both context and also the fact that opinions may in many situations reasonably differ, can affect any judgement of validity. We certainly don't have enough context to say much, but it's probably either opinion or 'received wisdom']
Answer: First, the table isn't really "valid" or "invalid". It's a general guideline that will apply in some situations and not others. In some fields an R of $\pm{0.5}$ is very strong, in some it is very weak.
Second, a perfect correlation is, indeed, large.
Answer: I would expand @Peter's

In some fields an r of 0.5 is very strong, in some it is very weak

Clearly, in social sciences based on surveys/testing, correlation 0.5 between questions or items is considerably large; that same value will be seen as negligibly small in some branches of physics.
But another facet of it is the shape of the distribution and the degree of discretization of the scale.
Pearson $r$ theoretically varies between -1 and +1. However, in real data the empirical range that will not let out $r$ - computed between two given variables, - is usually narrower than the theoretical one. Linear correlation between X and Y has a chance to attain +1 if and only if the shape of the distribution is totally identical in X and Y (in other words, the two distributions differ no more then just linearly). Otherwise, the upper bound for $r$ will be lower than +1. Analogously, $r$ could attain -1 only if the shape of the distribution is fully identical in X and -Y; otherwise the lower bound for $r$ will be higher than -1. In order $r$ to have empirical range of variation as the theoretical one, -1 to +1, the two distributions must be not only identical in shape, - they must be both symmetrical in shape.
Real life correlating variables often have different and asymmetric distributional shapes. That means that $r$ for them has narrowed freedom to vary and can never reach +1 or -1 values. In the following example, X and Y correlate with $r=.573$, but those data could never give $r>.808$.
X(sorted)  Y(asis, going with X)) Y(sorted ascendinhly, like X)
   4                  4                   3
   4                  4                   4
   4                  5                   4
   5                  3                   4
   5                  4                   4
   5                  4                   5
   5                  6                   6
   5                  6                   6
   6                  6                   6
   6                  7                   7

r(Xsorted,Yasis)= .573  -  actual observed correlation
r(Xsorted,Ysorted)= .808  -  maximal correlation attainable with the observed data

What does considerable narrowing of the range for $r$ mean? It means that the strength of the association between the two variables is underestimated by the traditional $r$; and the more it is undrestimated as the stronger is the association. Because strong association is then inevitably nonlinear, but $r$ skims only linear portion of it. If the analyst facing this problem comes wishing to scoop out more of the association, he would probably think of using a nonparametric Spearman $rho$.
But an alternative an seemingly reasonable solution would be to rescale the observed $r$ value to the upper (or to the lower, or to both) its empirical bounds(s). With the example above, $.573/.808=.709$ may be regarded as the "corrected" or "true" magnitude of $r$ in the context of our specific data. Spearman $rho$ is measuring linear relationship after streightening curved relationship (by ranking). Rescaled $r$ is referencing itself to the ceiling of the linearity possible with the given data. The ceiling or bound value of $.808$ could be, in a sense, labeled "perfect association" despite that it is less than $1$.
Such rescaling, has, of course its shortcomings, the main being is that a matrix of such coefficients is often not positive semidefinite.
If the data measurement scale is coarse, such as dichotomous, data react sharper to the inequality of marginal distributional shapes, and the empirical range for $r$ is narrower than it is with fine scale. As seen below:
Histograms

Two interval variables with different shape of distribution:
   ooo
   ooo      oooooo
oooooo      oooooo
oooooo      oooooo
123456      123456  <- 6-grade scale
The upper empirical bound for r of these data = .956

The same two variables binned into dichotomous scale
(inequality of distribution shape preserved):
    o
    o
    o
    o        o  o
    o        o  o
    o        o  o
 o  o        o  o
 o  o        o  o
 o  o        o  o
 o  o        o  o
 o  o        o  o
 o  o        o  o
 2  5        2  5  <- dichotomous scale
The upper empirical bound for r of these data = .707

And it is the reason why factor analysis done on binary data via Pearson $r$ often give flat scree plot, suggesting too many factors to extract. Strong correlations just have little chance to occure in binary data with varying item difficulties (i.e., marginal shapes). Torgerson adviced then computation of the above rescaled $r$ values, which are higher. Another way out is to compute tetrachoric $r$ which is also higher than ordinary $r$.


Can the DM interfere with a spell?

Question: Can the DM add in obstacles such as by adding weather, a low class creature accidentally bumping in to the caster, or just a simple acorn falling out of a tree to disrupt a spell?
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/43285/discussion-on-question-by-jigoku-can-the-dm-interfere-with-a-spell).
Comment: The question is "Is it within the GM's purview to situationally apply or even bend the rules?" - how is this too broad?
Answer: Yes, heavy weather can interfere with concentration:

Concentration DC1
Distraction

5
Weather is a high wind carrying blinding rain or sleet.

10
Weather is wind-driven hail, dust, or debris.

Distracting spell's save DC
Weather caused by a spell, such as storm of vengeance.4

If you are trying to cast, concentrate on, or direct a spell when the distraction occurs, add the level of the spell to the indicated DC.
If the spell allows no save, use the save DC it would have if it did allow a save.

The motion of a ship in a heavy storm can also incur Concentration checks: DC 10 for "Vigorous motion ([...] in a small boat in rough water, belowdecks in a stormtossed ship)," and DC 15 for "Violent motion ([...] in a small boat in rapids, on the deck of a storm-tossed ship)."
Weather conditions are certainly part of the DM's prerogative as the player in charge of the world and environment. Ideally, of course, weather behaves naturally, and sudden shifts in weather are rare and unusual, or caused magically.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/43286/discussion-on-answer-by-kryan-can-the-dm-interfere-with-a-spell).
Answer: Yes, the DM can interfere with a spell.
The DM controls the environment, the world, and everything that the players encounter.  The other players at the table only control what their characters can do within the limits of their role playing and in game capabilities.
From your comment under @KRyan's answer about weather.

Ok thank you that's good, my friend decided to be a sorcerer and I
  just wanna piss him off coz he thinks he's the best at everything –
  Jigoku

Should the DM interfere with a spell?
That depends, and gets to the matter of Rule Zero.  There are two very thorough answers to that by KRyan and by mxzyplk, both of which provide in depth consideration of when a DM should exercise discretion and act with "the hand of God" -- and when that can be an obstacle to fun at the table.
@KRyan made a comment to your question that I will fold into this answer.  (He's very experienced in DnD 3.5e, and I'd consider him an expert witness).

Can the DM do some of these things? Yes. Can the DM do all of these
  things? Well sooner or later his players are going to get fed up and
  leave; at that point, he can't. There is a balance to be struck
  between challenging players and portraying a realistic, difficult
  world, and just irritating people.

Sometimes, the DM' "hand of God" alters play constructively.  Other times, the DM "hand of God" alters play destructively.  Make sure you consider that, and the fun of the players at the table, before you make a "hand of God" decision.  Fun is why we play.
Answer: Absolutely! However, nerfing the players simply because one can is a jerk move. If the player has the ability to cast a specific spell, and her doing so makes sense in the situation, there's absolutely no reason to interfere with that UNLESS said interference also makes sense. For example, if the DM regularly rolls a percentage die to see if atmospheric conditions are blowing stuff around that could cause the player to lose their action, then yeah, that would make sense. If however he's doing it just to make the encounter more difficult, then he obviously didn't anticipate the player's creative solution, and the DM just needs to eat it and award XP accordingly.
Personally, I love giving extra XP for creative solutions. I feel it encourages the players to connect much more vividly with their world, and it makes them feel like they can actually outsmart the bad guys once in a while instead of simply beating them to death.
If a DM finds themselves messing with the world to make it more favorable to the story they have in their mind, they're doing their job wrong.
The DM's world should be robust enough for the players to do anything they are capable of doing, and the DM should have the ability to react to the players' actions; not the other way around.
Edit: Regarding your friend playing a sorcerer, try putting him in a place where he will be forced to learn discipline and humility. I tend to run high level games nearly exclusively, and with high level players, there's almost nothing they can't magic up, or bash away. As DMs, we tend to think of challenges in terms of high level foes, but what if you had a frail magician who was stranded on an island filled with thousands of primitive warriors, and he could only ask the chief shaman for help? What if the chief lived at the top of a large jungle covered mountain, and the wizard had to traverse the jungle in three days with only a knife, a water skin, and was forbidden from using magic on their sacred land?
There would be no way he could overcome those numbers, and would be forced to undergo a very personal and primal journey, using only his wits and strength to survive. This would force the player to use skills he thought he would never need when he created his optimized character, and would cause the player to grow as well.
These are the kind of challenges I have found DMs tend to not use, but I think that much like today with technology, there are still parts of the world where technology will not help someone, and building that creativity into a world makes it a real adventure at any level.
Comment: Hi, welcome to the site. I recommend you check out the [Tour]; we do try to aim for a fairly professional level of style here, and part of that is limiting vulgarity. In some cases (say, if it were part of the name of a feature or something in an RPG), you could use vulgarity, but not merely as a stand-in or intensifier.
Comment: You got it man. Sorry about that!

Can the DM interfere with a spell?


Where can I find all Bukari and Muslim hadith related to hijab of women?

Question: Is there a collection of all Sahih-Bukhari and Sahih-Muslim hadith about hijab/covering of women? I didn't get clear answers to this question, so I was looking for a place where all authentic hadith related to the subject would be, so that I could study myself?
Answer: A short info on the compilation of both Sahih's
Each author of hadith compilations has compiled the ahadith he relies on in different  chapters, some or maybe even most of these authors might have compiled the same hadith (content) in different chapters based on the related topics. Among those authors al-Bukhari is certainly the one with the most authentic ahadith compilation. Imam Muslim mainly has chosen to further support the more authentic narrations he had at hand with other authentic ones (either by fully quoting them or by only quoting deviations in the narrator chain or content) in the same chapter. However Sahih Muslims originally was a book of 54 "head chapters" the subsection titles and order as we commonly know today are the creation of imam an-Nawawi, as imam Muslim left these details out, other commentators of Sahih Muslim have chosen other titles, orders and selections of the hadith of a "head chapter".
Others might have chosen to avoid duplicates and might have quoted a hadith only once in their book.
Re-phrased question
Having this said I can answer your question based on the following re-phrased version:

"Is there a chapter in Sahih-Bukhari and Sahih-Muslim where I can find all ahadith about hijab/covering of women?"

Both Sahih books have chapters on the topic of clothing
So if you check Sahih al-Bukhari you will find "The book of Clothes and Adornment" this is the head chapter to look inside here.
As for Sahih Muslim the corresponding chapter is "The book of Clothes and adornment".
None of both Sahih's addresses the "hijab" as a specific topic
However you won't find them mentioning hijab itself, but the focus of the corresponding chapters in both books is more on:

the order of covering the 'awrah:
for example the prohibition of nudity (see here in Sahih Muslim, but in a different chapter) or
inappropriate clothes which are disclosing (see in Sahih Muslim here) or
the prohibition to look at the 'awrah of others be it from the same sex or different genders (see here in Sahih Muslim, but in a different chapter) or
the prohibition to do alike the non-Muslims (generally and in the context of clothing especially (see here in Sahih Muslim and here in Sahih al-Bukhari)
the prohibition for women to act or wear like men (see in Sahih al-Bukhari here, here and here)

Hijab was ordered by the qur'an
Before leaving the impression that both authors of Sahih hadith, didn't consider hijab as obligatory and only mentioned narrations about "appropriate clothing" in their books.
We must check the entire book and we will find that they refer to the qur'an as the revelation which ordered "hijab" in different ahadith -in the following I'll only share a few, but not all of them-:
In Sahih al-Bukhari in the book of Tafsir when quoting ahadith on the verse (33:53) here, here here and in the following ahadith and elsewhere. Al-Bukhari also quoted in his Sahih this hadith -which was also compiled by abu Dawod (see later)- when addressing the Tafisr of the verse (24:31) which make clear how the Sahabi women () understood and interpreted this verse.
Imam Muslim quoted ahadith referring to the revelation of the verse on hijab here and here and elsewhere in the book.
Other sources go more in details
Most ahadith on the hijab which you may find are however covered in other hadith compilations like the Sunan Books of abu Dawod, ibn Majah an-Nasa-i and Jami' at-Tirmidhi or the Musnad of imam Ahmad and other compilations like Sahih ibn Hebban etc. most of these ahadith have a good level of authenticity, but among them are also weak ahadith. Nevertheless scholars may differ in their qualifications.
Among the rather known ahadith in this regards are:

When Surat an-Nur came down, they took the curtains, tore them and made head covers (veils) of them. (Sunan abi Dawod)

Asma, daughter of AbuBakr, entered upon the Messenger of Allah (ﷺ) wearing thin clothes. The Messenger of Allah (ﷺ) turned his attention from her. He said: O Asma', when a woman reaches the age of menstruation, it does not suit her that she displays her parts of body except this and this, and he pointed to his face and hands. (Sunan abi Dawod)


Paying extra on a mortgage. How much can I save?

Question: Can I pay $12,000 extra once a year or $1000 every month - which option  is better? The first option does sound better, but for a 30 year mortgage, is it that significant?  The mortgage is for $527,000 @4.375 fixed rate with no penalty for pre-payments. How much money and years on a mortgage can I save? When is the best time to pay? At the end of each year?
Comment: This should help: https://www.mtgprofessor.com/home.aspx
Comment: Duplicate (just multiple the extra $ by 10) of #8092.
Comment: The only reason I don't agree with the duplicate: $100 is just 'pay some extra'.  $1000 is '15 vs 30 year mortgage' territory.  Makes a big difference in the possible answers.
Answer:
Can I pay $12,000 extra once a year or $1000 every month - which option is better?

Depends when. If you mean 12K now vs 1K a month over the next 12 months, repeating this each year, now wins. If you mean saving 1K a month for 12 months then doing a lumpsum, the 1K a month wins. Basically, a sooner payment saves you more money than a later payment.

The first option does sound better, but for a 30 year mortgage, is it that significant?

Your number one issue is that you have a thirty year mortgage. The interest you pay on it is monstrous. For the 30 year term, you pay around 500K in interest. A 15-year mortgage is 300K cheaper (only 200K in interest will be paid). The monthly payment would be 1250 more.

How much money and years on a mortgage can I save? When is the best time to pay? At the end of each year?

You can knock off about a dozen years. Save I think ~250K. You can find mortgage calculators online or talk to your mortgage advisor to play around with the numbers.
Comment: I challenge the assertion that 6% is a "conservative" investment.  By writing "For the 30 year term, you pay around 500K in interest" you imply that OP **will** pay $500K interest.  But it's only true if OP pays the minimum every month.
Comment: If OP invested the 1K/month in equities earning 6% in average annualized returns over thirty years, they'd have 1000000. So, the extra 1K/month payment is a "guaranteed" 250K savings whereas conservatively investing may net a million. The choice is up to OP but I realized it is irresponsible of myself to not mention this.
Comment: @lan no it's not. currently S&P500 is at 2400. 30 years ago it was at 650. Which means it's now 3.68 times it was. This translates in an average of about  4.3%.
Comment: @PieterB That is inflation-adjusted and is not including the dividends. If you don't adjust for inflation, it went from 290 to 2400. Which is 7.3. If you adjust for reinvesting the dividends, it was 9.6%.
Comment: The "invest vs pay off mortgage" question is an interesting one but not part of _this_ question given it's well covered elsewhere.
Comment: @RonJohn The long run average for the S&P 500 is 11%. 6% is conservative. (I am using non-inflation adjusted returns since the mortgage itself is not inflation adjusted.) You are correct about the 500K interest comment. I am comparing minimal payments to 12K/year more which is not appropriate if OP is already paying above the minimal payment.
Comment: Interesting to simultanesously say, "The interest you pay on it is monstrous" and also, "it's irresponsible not to suggest borrowing money at that rate to invest in an index tracker" ;-) Not saying you're necessarily wrong to say either thing, just that it's interesting how different approaches lead to different adjectives.
Comment: What I meant to say Steve is that I can't in good faith mention how much one "saves" in interest by paying early without acknowledging that in economics one evaluates their next best alternative. Including risk.
Answer: "When is the best time to pay? At the end of each year?"
If you save $1,000 each month at 1% so as to pay $12,000 at EOY on a 4.75% loan, you've lost "4.75% - 1% = 3.75%" over that year.  (And that's presuming you put the money in a "high yield" online savings account.)
Thus, the best time to pay is as soon as you have the money.
EDIT: This all assumes that you have an emergency fund (more than the bare minimum $1K), zero other debt with a higher rate than 4.75% and that you are getting the full company match from 401(k).
Answer: Paying $12,000 in lump sumps annually will mean a difference of about $250 in interest vs. paying $1,000 monthly. If front-load the big payment, that saves ~$250 over paying monthly over the year. If you planned to save that money each month and pay it at the end, then it would cost you ~$250 more in mortgage interest. So that's how much money you would have to make with that saved money to offset the cost. Over the life of the loan the choice between the two equates to less than $5,000.
If you pay monthly it's easy to calculate that an extra $1,000/month would reduce the loan to 17 years, 3 months. That would give you a savings of ~$400,000 at the cost of paying $207,000 extra during those 17 years. Many people would suggest that you invest the money instead because the annual growth rates of the stock market are well in excess of your 4.375% mortgage. What you decide is up to you and how conservative your investing strategy is.
Answer: If you're truly ready to pay an extra $1000 every month, and are confident you'll likely always be able to, you should refinance to a 15 year mortgage.
15 year mortgages are typically sold at around a half a point lower interest rates, meaning that instead of your 4.375% APR, you'll get something like 3.875% APR.  That's a lot of money over the course of the mortgage.  You'll end up paying around a thousand a month more - so, exactly what you're thinking of doing - and not only save money from that earlier payment, but also have a lower interest rate.  That 0.5% means something like $25k less over the life of the mortgage.  It's also the difference in about $130 or so a month in your required payment.
Now of course you'll be locked into making that larger payment - so the difference between what you're suggesting and this is that you're paying an extra $25k in exchange for the ability to pay it off more slowly (in which case you'd also pay more interest, obviously, but in the best case scenario).  In the 15 year scenario you must make those ~$4000 payments.  In the 30 year scenario you can pay ~$2900 for a while if you lose your job or want to go on vacation or ... whatever.
Of course, the reverse is also true: you'll have to make the payments, so you will.  Many people find enforced savings to be a good strategy (myself among them); I have a 15 year mortgage and am happy that I have to make the higher payment, because it means I can't spend that extra money frivolously.
So what I'd do if I were you is shop around for a 15 year refi.  It'll cost a few grand, so don't take one unless you can save at least half a point, but if you can, do.
Answer:
How much can I save?

Depends on inflation and what other investment opportunities you have. It could end up costing you millions.

Can I pay $12,000 extra once a year or $1000 every month - which option is better?

It depends on how risk adverse you are.

The first option does sound better, but for a 30 year mortgage, is it that significant?

How much of your time is it going to cost you to do it every month? What is keeping you from doing it every day? How much is your time worth to you. Giving the bank its money sooner is always better than giving it it's money from a saving interest perspective.

When is the best time to pay?

See above.


Remote Desktop Connection through VPN cannot see computers on network

Question: I am trying to connect to my work desktop computer through a VPN connection using Microsofts Remote Desktop Connection at home.  I get a successful VPN connection but when I enter my work computers name, userid, and password through Microsofts Remote Desktop Connection I get a "Cannot find Computer" error message.  If I use the IP address instead of the computer name I am able to successfully log into my work desktop computer.  How come my remote VPN connection cannot see my work computer's name but the IP address works fine?  Also when VPN connected I cannot see other computers on the work network. I am able to remote desktop connect using my computers name when I am at work on the same LAN.  I know many would say what's the problem, just use the IP address.  However, I am trying to set up a remote desktop access proceedure for other employees in the company who are not that computer literate.  I can easily find my remote computers IP address but it is not that simple for others.  I am running Windows 7 Professional on our work desktops and VPN through our Windows 2008 R2 Server.  Any ideas?
Comment: I suggest you set up a DNS server and WINS server and then add those options to your DHCP settings so your VPN clients pick them up
Comment: Again, Phil is on the money. Network Neighborhood/My Network Places is populated via NetBIOS broadcasts, which I'm sure aren't being transported across the VPN. The way to deal with this (as Phil mentioned) is to set up a WINS server on the LAN and configure the VPN server to assign the WINS server address to the VPN client. That will take care of the network browsing issue. As for DNS you'll need to make sure that the VPN server assigns the LAN DNS servers (and LAN DNS suffix) to the VPN client so that you'll have DNS name resolution of the LAN clients when you're connected to the VPN.
Comment: Thanks all...You have given me a good roadmap to get started fixing the problem.  I have some homework to do before I get back to you but I think I understand what to do.
Comment: Phil is on the right track here. What VPN solution are you using (client and server)? What name servers are you getting with the VPN connection? As far as seeing other work computers while you're connected to the VPN is concerned, do you mean from the RDP session or from your local, vpn connected workstation?
Comment: Afte I VPN in I use windows explorer and look at my network connections.  I can only see my local connections.  I would have expected to see computers/devices that are on my work local network throught the VPN.  I do believe it is a netbios issue.  I set up the server myself and I believe I do not have a fully operational DNS/WINS/NETBIOS system up and running.  I definitly don't have a DNS running and I have never set up any of the netbios configurations.  Comments are welcome but let me go do some reading on netbios.
Answer: Given that you can connect by IP address, the problem is one of name resolution and is likely to be a NETBIOS/DNS issue
At work, your machines are probably on a domain such as "company.local" so when you connect to, say a machine called WORKSTATION its FQDN (Fully Qualified Domain Name) is actually WORKSTATION.company.local
At work you will likely have a fully operational DNS/WINS/NETBIOS system up and running so both the short and long versions work
At home, I suspect that the VPN is not picking up the correct name servers.
If you try connecting to e.g. WORKSTATION.company.local i.e the long name, does it work?  If so then its a WINS/NETBIOS problem but if not it is a DNS issue
Comment: Thanks Phil...Done my homework and now understand.  Thanks.
Answer: Do you have split tunnelling enabled over your VPN connection? If yes, read on. If no, ignore this advice!
Problems
Perhaps your VPN client is sending DNS requests to the local side of the tunnel rather than the remote side. AFAIK, some VPN clients will try a request on one side of the tunnel, and if this fails, the client tries the other side. It it tries the local side first and your configured DNS server doesn't respond properly with an error when it doesn't find the address (perhaps it's configured to redirect you to adverts etc.) then that might break it.
Suggestions
If possible (and if you have a split tunnel) try disabling your split tunnel. They're a pretty bad idea from a security point of view anyway...
If this isn't possible, when you're at home try changing your home DNS settings to Google's public DNS http://code.google.com/speed/public-dns/ these servers shouldn't issue redirects, so you should get a proper error response...
Comment: No split tunnelling...


Should we compare the individual monthly forecasts with actual values?

Question: Hi
I am using Linear and exponential forecasting models to do sales forecasting. In the model itself, we use the forecasts of period t to get next forecast and so on.
While analyzing the accuracy of the forecast using Mean Absolute Percentage Error, I get good results. But when I compare the intermediate forecast values of the model against the actual time series data, I can see some big Percentage Errors like MAPE might be 15%, but some of the intermediate percentage errors might be as high as 80% and some will be pretty low. So the MAPE averages out to low.
I wanted to know
1) Is it wise to compare these intermediate forecasts with actual values?
2) Can we use these high intermediate forecast values to say that forecasts for so and so month might be unreliable?
Answer: Yes, you should absolutely compare your predicted values with actual values.  This is good practice with any kind of statistical modeling, not just time series analysis.
If certain months are consistently off, you should use a seasonal model.
Answer: MAPE is known to have problems, when the time series have values close to zero. Check whether this is the case, since high MAPEs may be the problem of time series values close to zero, not of model accuracy. For a discussion on accuracy measures I recommend this article by Rob Hyndman and Anne Koehler.
If it is not the problem with MAPE, @Zach advice is spot on, you should always  compare the forecasts with actual values, that is how you know how good your forecasts are.
Comment: Well, my forecasts are as expected according to seasonality but the actual values are either high or lower than the forecast. That might be due to randomness in the data or some other factor. This is giving high MAPE for these cases. I am already using deseasonalized data. Should I remove the randomness component as well from the data and then do the forecasting.
Comment: @Abhishek, how do you usually remove (or intend to remove in this case) randomness component?
Comment: I am not sure about that. I guess that won't be possible since it is randomness which can't be predicted.


I want to take a bus from Dusseldorf Airport to NH Hotel City Centre - please tell me what would be the bus number

Question: How to reach NH Dusseldorf City Centre Hotel from Dusseldorf Airport?
Comment: What time are you arriving at the airport? From Google Maps, it seems the easiest way is to take the 707 tram (includes about a 20-minute walk). There doesn't seem to be a direct bus.
Answer: You first take the train to Düsseldorf Hbf (main station). It is a 5 to 10 minutes ride (depending on the number of stops) and there are some 6 to 8 trains/hour.
From there, you can either walk about 10 minutes to your hotel or take the 709 or 719 tram to the "Berliner Allee" stop and walk from there.
Taking a taxi from the airport to the hotel is of course also an option and will cost you about 20€.
I don't know why Google Maps suggests to take the 707 tram all the way. That sounds like one of the least attractive options.
Comment: Google Maps doesn't always seem to know about German trains, so can often suggest odd routings by public transport using only ones it does know about


Subletting in California on a month to month lease

Question: I have a friend who is a sublandlord in California and he's on a month to month lease. He wants to move out because the house is in a terrible condition and the subletters are terrible roommates. How can he legally do this?
Comment: What terms does he have with his subletters? Are they on leases, or month-to-month?
Comment: They are not on the lease and they are month to month. They have lived with him for about a year and a half.
Comment: Is he allowed to sublet or is he doing this outside his lease?
Comment: The landlord gave permission. As far as the legality on that front, I do not know.
Comment: Does "I have a friend" keep this from being a request for legal advice.
Answer: Then if they are just month-to-month he should give a "30 day notice to quit" or a notice not to renew at the next rent payment. If they have been living in the property for more than a year, he will have to give a 60 day "notice to quit". There are certain circumstances that allow shorter periods (like failure to pay rent, violating a lease, or drug dealing from the property).
The "notice to quit" does not need to state any reason, only that they need to be out by a certain calendar date. The landlord should get a copy of this, sending it by registered mail is best, but other methods like sending email with read receipt may work as well.
Answer: Your friend (the sublandlord) is a tenant of the owner, and must give the owner notice that he (the sublandlord) will be moving out. The legal requirement to give the owner notice won't be satisfied by copying the owner on the sublandlord's different notice to the subtenants.


Is there a way to use punctuation in Siri dictation?

Question: Is there a way to use punctuation in Siri dictation? For instance, if I tell Siri to text someone "want to meet for dinner?" - it won't track inflection, right? How can I add the question mark via voice?
Answer: http://howto.cnet.com/how-to-make-siri-use-punctuation/8301-11310_39-20124379-285.html
To get Siri to use punctuation, you only need to speak the punctuation during the composition of your message. For example:

Hi comma how are you question mark did you see the game last night
  exclamation point question mark.

Speaking that exact line to Siri would equate to the following message:

Hi, how are you? Did you see the game last night!?
Comment: What would really impress me is if you could say "interrobang" for that last mark. :)
Comment: I appear to have reached me up vote limit today so +1 from me
Answer: CrushApps has a comprehensive list of commands and punctuation that Siri understands.
Here's a short summary as requested by Daniel. These are the ones I find most useful day to day.

"all caps on ... all caps off": "I am so all caps on hungry all caps off I could eat a horse" -> I am so HUNGRY I could eat a horse
"exclamation point": "You're the man exclamation point" -> You're the man!
"question mark": "What was that question mark" -> What was that?
"smiley" or "smiley face" or "smile face": "smiley face" -> :-)
"winky" or "winky face" or "wink face": "wink face" -> ;-)

But there are many more that include a surprising amount of edge cases. It's possible to dictate the following sentence: "The number, "pi", is ... 3.14 (approximately)."
Comment: Can you summarize any of that here, or is it too long?
Answer: Apple has added the complete list of punctuation you can dictate to the Knowledge Base.
Mac Basics: Dictation


How did Joseph inherit Hamon from Jonathan?

Question: I was watching JoJo's Bizarre Adventure and on the episode where Jonathan dies, Erina takes a random child.
When Part 2 started, how did Joseph "inherit Hamon from Jonathan" if he isn't directly related to him?
Answer: He inherited the Hamon ability from

 His mother, Lisa Lisa. She is an expert in Hamon. Well, since they have another Hamon's user other than Joseph in his family, the percentage Jonathan inherited the Hamon's is quite huge. Also his father, Goerge Joestar II was the son of Erina Joestar. However, George Joestar II did not inherit Jonathan's Hamon ability. Instead, his son, Joseph Joestar, had the ability of Hamon.

But from Wikia, it stated that he got Hamon's ability from

 Jonathan Joestar.

 The young Joseph developed early an ability to use the Ripple inherited from his grandfather, first displaying it when Speedwagon was being kidnapped.

Here is a video on YouTube when he used Hamon for the first time
A user from the JoJo's Wikia page explains that too.

 His father is Jonathan and Erina's son, George II. Lisa Lisa is the one who isn't related. Though I expect having some of Lisa's blood helped with learning it faster.
Answer: Joseph is Jonathan's descendant. Erina was already pregnant when they boarded that ship, the random child she saved later married her son and gave birth to Joseph.
Answer: "George Joestar II was born just months after his father died at the hands of Dio Brando. His mother, Erina, was pregnant at the time of Dio's assault and raised George primarily by herself. He grew up to marry the child who was saved by Erina at the time. Together, they had a son named Joseph Joestar." Taken from JoJo's bizzare adventure wiki search
Answer: George Joestar II was hinted to have hamom by speedwagon himself. He said that George was an ordinary man however he had the makings of a Hamon master which means that if he had been taught then he would've been able to control his hamon at will. Most likely George had the same experience of hamon as his son did before he had gone through hamon training. So basically sub consciously using hamon without realizing it. So he basically inherited from both of his parents.
Comment: this doesn't really answer the question, as the question goes under the assumption that Joseph is not blood-related to the Joestar line. OP didn't realize that Erina was pregnant already by the time they took the ship, so he/she believed that she just raised the child she saved and had no true Joestar descendant. Whether George had Hamon is of no consequence to this question.
Answer: But he is. He is his grandson. Jonathan and Erina had George, later he and Lisa Lisa would have Joseph. He is 25% Jonathan. You could find family trees out there that also show more of the joestar family because once dio took Jonathans body it got a bit more complicated. For the hamon explanation i think George had a bit of hamon once said but im not sure but Lisa Lisa was trained by straitzo which means even if he isnt a joestar his mother is a hamon user.


If a batter is injured, while hitting a home run out of a park, and cannot physically run the bases, can a pinch runner be used?

Question: If a batter is injured, while hitting a home run out of a park, and cannot physically run the bases, can a pinch runner be used?
Comment: Welcome to Sports Stack Exchange! Can you please add your actual question to the body text? Right now the title is the only thing providing any information.
Comment: https://www.youtube.com/watch?v=mRnr6sA7UDQ Gape Kapler was on base when a teammate hit a home run, but fell rounding 2nd base and could not continue. Play was paused, a pinch runner took his place, then play resumed with both runners continuing to home. (The player that hit the home run alertly did not pass Kapler, as that would have resulted in him being called out.)
Answer: If a batter-runner is incapacitated during a home run (or any other play where he is entitled to a particular base, such as a walk, a ground rule double, or a ball thrown into the dugout), then his team may use a substitute runner (who then takes his place in the batting order and on the field, unless further replaced).  See the MLB Official Baseball rules, from rule 5.12:

When an accident incapacitates a player or an umpire;

(A) If an accident to a runner is such as to prevent
him from proceeding to a base to which he is
entitled, as on a home run hit out of the playing
field, or an award of one or more bases, a substitute runner shall be permitted to complete the
play.


inkscape keyboard shortcut for resize

Question: What is the inkscape keyboard shortcut (no mouse drag) equivalent of
Ctrl+mouse drag to resize an object?
I am trying to resize 2 objects by same factor. However with mouse it is difficult to know how much is resize. Selecting both object together and resizing using Ctrl+mouse drag moves 2nd object out of original position!
Comment: When resizing two or more objects, you are resizing the space separating them as well. When I need to resize in a precise manner, I change the units to percent on the toolbar and enter a value. Is this an option for your objective?
Answer: If you group the two objects together, they will both resize by the same factor and remain in their original positions in relation to one another.
Alternatively, you could click the lock icon on your sizing toolbar and use the up or down arrow to adjust the size a little bit at a time, but I think just grouping them together should do the trick.
Let me know if this helps!
Answer: Use the transform dialog (Object > Transform), and activate the checkbox 'Apply to each object separately' for having full numerical control.
The complete keyboard shortcut list (for other shortcuts) is available online:
https://inkscape.org/en/doc/keys092.html
There is no shortcut for resizing without the mouse other than via the transform dialog or the input fields in the selection tool's tool controls.

inkscape keyboard shortcut for resize


In RHEL5, How to authorize common user to use command such as userdel and useradd

Question: I want to authorize to common user to be administrators. So that those authorized users can create accounts, delete accounts, modify password, modify password rules.
I know su could help, I wonder if there are any other methods that works?
Thanks a lot!
Answer: sudo is the usual method (man sudo).  It allows you to specify that a particular user can run a particular set of commands as a different particular user (usually, but not always, root), authenticates them with their own password to prove that they're them, and logs what they've done.  Users and commands can be grouped for easy administration.
Note that there can be issues with commands that allow shell access, or editing arbitrary files; if, say, you allow someone to sudo vi as root, you're effectively trusting them to do anything as root (though there are mitigating measures that can be taken even against that).  But such issues aside, it's an excellent system for delegating trust, and most sysadmins I know have been using it for years.
Comment: MadHatter, thanks. Sodu is really of great help. I think it can works
Answer: What are you exactly trying to accomplish? If in your case you are offering e-mail or web page service, and you would like to delegate the account management of those accounts to some other users, then it might be a good idea to separate those accounts from the actual system accounts. That way restricting the things the people can do at your server is much easier and clear. So, keep only the system accounts in /etc/passwd and separate everything else to MySQL/OpenLDAP/some other system.
Since I don't know what you are actually going to do, I'm not going to type a long tutorial, but here's the concept in a nutshell. I assume here you need to provide an email service and someone (or something, such as a Perl script) needs to modify the user accounts for that. Let's put the accounts to OpenLDAP.
1) Install the POP/IMAP server software of your choice. Most, if not all, of them do support PAM authentication.
2) Install pam_ldap (and most likely nss_ldap), so you can point the authentication phase to lookup the accounts from OpenLDAP.
4) Configure your mail software to use LDAP and/or modify /etc/pam.d/{pop3,imap} to use pam_ldap.
5) Create your initial OpenLDAP database with the needed LDAP schema. There are scripts bundled with the OpenLDAP that can do that for you.
6) Install the LDAP administration tools of your choice. Command-line tools, web-interfaces, GUIs and APIs are all available.
7) Give your trustees access to your LDAP administration interface.
8) Make sure that only e-mail service is available through LDAP authentication and not the other services, such as normal shell login.
9) Bang! Your trustees can administer your e-mail accounts but not easily harm your server.
Comment: Janne, thanks for your detailed suggestion. I think it is a good way. But I only want to use the command userdel, useradd, so I think it won't need LDAP. Anyway, your suggestions is very valuable.:-)
Comment: "Only"? Do you realize that with useradd and userdel someone could replace your root account and that's the end of story?
Comment: Janne, besides, it should also authorize the user to modify password rules (for example, modify /etc/pam.d/system-auth).  :-)  Maybe your method could help solve more difficult problem. Thanks.


What is time to give reply to advisory action if it is received after 3 months of Final Office Action mailing date

Question: Advisory action is issued by USPTO if reply to final office action is within 2 months from mailing date of final office action and also reply time to Final Office Action including Advisory is 3 months from its mailing date. What if advisory action is received after 3 months from mailing date of final office action ?
Answer: As indicated in the Advisory Action, the date for reply will be the date of the Advisory Action as it is later than the 3 month date set forth in the final Office Action.  As you will respond to the Advisory Action after the date of the Advisory Action, you will need a one-month extension if filed within one month of the Advisory Action.  Of course, you will still need to resolve everything within 6 months of the date of the final Office Action, be it by filing an RCE or Notice of Appeal, getting the examiner to allow the case, or letting it go abandoned.


What is the best method to patch a large hole (2-3 inches) in drywall?

Question: I have a large hole where a TV wall mount once was (I believe the hole was used to run power and coax cable to the TV). I have since moved the TV and would like to patch the hole. What is the best way to do this?
Comment: Hmm... this is just the size of a fist ;)
Comment: I don't know what you're talking about, that is a small hole.
Answer: Correct way to do it as instructed on 'Canada's worst Handyman':

cut a piece of strapping (wood) that will be a couple inches longer than the hole on each side.
put the strapping inside the hole and attach it using a couple of drywall screws so that it is across the hole.
cut a piece of drywall that is the same size as the hole, as close as you can get
attach the patch to the strapping with a drywall screw
mud, sand, paint.

Same process works for larger holes and also on the ceiling which can be tricky.
Comment: When you're trying to get the strapping in, temporarily put a long screw into the center of the strapping. Once you get the strapping through the hole, use the screw as a handle to pull the strapping towards you while screwing in the two ends of it. Then remove the "handle" screw, and attach the drywall "patch"
Comment: The only time I would cut it larger is to square the hole up, to make the patch easier to make it exactly the same size.  That would allow you to use less mud.
Comment: +1 - exactly what I was going to suggest.  Also, even though it seems counter-intuitive, it might be easier if you actually cut the hole a bit bigger in this case.
Comment: I usually do this using paint stir sticks, though they often split.  Another "optimization" is to smear the stick with construction adhesive.  The next day you can back out all the screws, and the glue and mud will hold just fine.
Comment: @dilbert - yup, was thinking more if it's too small to easily get that piece of strapping in (and hold it while you screw it to the drywall)
Comment: I'm considering using this technique to close a hole left from an old heating vent register. I'm curious though -- after the process is done, how strong is the new wall section? Does it feel different if pressed upon?
Comment: I would think it should be close to straight drywall between the strapping and the mud helping to hold it.
Comment: For a newb, could you elaborate on what type of wood would serve effectively as "strapping"?
Comment: @Anticipation 1x4 pine, perhaps
Answer: There's an alternative to @dilbert789's solution when you're dealing with holes this small:

cut a rectangle of drywall about three inches larger than your damaged area in both dimensions.
score the back of the drywall one inch in from each edge.
break the drywall at the score line, and then remove the drywall from the paper.
trace the drywall portion of the patch onto the wall, over the damaged area.  (the part that's still solid, not the paper that's 2" larger on each side)
cut out along that line.
test plug for fit, and if necessary, clean up the edge some
put down some drywall mud on the inside of the lip of paper.
insert the patch into the hole
mud over the edges
let dry, sand, and paint.

I would still use @dilbert789's answer for larger holes, though, or anything in the ceiling, but I had a few incidents of wrestling with strapping when repairing similarly sized holes (fists, doorknobs, etc.), as you need to hold the new reinforcement, the screwdriver, a screw, etc, which gets difficult to juggle for one person.
Comment: My brother refers to that as a "hot" patch.
Answer: Use a drywall repair patch. They are cheap and easy to find at the big box stores.
And here's a video on how to do it:
http://www.youtube.com/watch?v=qvtoikKG318
Comment: For a 2x3" hole I would think the patch would be starting to push it. There isn't much structure to it for a larger area.
Comment: Instead of using it on the finished side of the wall, place the patch on the back side of your hole - tie a string (anything to hold the patch against the backside of the sheetrock) to the center of one of those mesh patches and pull it tight to the inside of the wall and then fill in the gap with mud.  Yeah it's still a pretty ghetto fix but still better than just mudding over one of those patches applied to the outside of the wall.
Comment: Those things are basically useless.
Comment: I actually found a case where I had to use one of those patches, for a much larger hole -- the main bathroom had been redone before I bought my house. Right above the toilet started developing a little bubble, an slowly got worse; when I went to cut it away to repair, I found that they had cut away the back to drywall to fit around a connection in the (cast iron) soil stack.  I used a large patch, so I could get some air gap between the wall and the pipe, so it didn't happen again.  (I assume it was condensation on the pipe)
Answer: They sell dry-wall patches for this purpose.
Answer: Do you have a stir stick for paint handy? Slap some thick glue on the ends and glue that in as your backer. No need for screws on such a small hole.
If you're daring you can just mud the inside lip of the hole and squeeze a plug cut to shape in there, too. But then you run the risk of it tilting all funny.
Comment: Remove the question (reword the statement, which is correct without it), remove the section about no backer (it's not worth it), and I'll change my down-vote to an up-vote. :)


Why some WWII fighters still have fabric/wood control surfaces?

Question: I've heard people say that the reason US in WWII preferred designs with fabric control surfaces with either a metal or plywood frame is they can sustain some small arms fire without disintegrating. Is this really the reason? Or is it simply weight saving?
Comment: You may find the story of the British [Mosquito](https://www.youtube.com/watch?v=vh4vazBq-X4) interesting although it was timber skinned. The video is complete with pipe-smoking, tweed jacketed boffins, pointless music, and good old-fashioned English commentary. Apparently a senior German commented that the British had created a plane that could be built in parts in every piano workshop in the country!
Comment: @Transistor, making it in carpenter shops was kinda the point. All metal was already used for weapons production, and all metal workers were already busy making them, so using wood—and it was not just skin, it was all-wooden construction—allowed to use additional material and workforce that wouldn't be taken from production of any other weapon.
Comment: Yes tactically and strategically for the British the Mosquito among other organic-skinned aircraft were really feats of engineering that made the best of what they had to work with. However, if I was going to send my pilots off to fight for our country, I'd go metal regardless of the time period.
Answer: It was done to achieve the most flutter resistant surface for the least weight.  To prevent flutter you balance the surface to put the C of G of the surface at or ahead of the hinge line so it can't oscillate in sympathy with the wing, which adds energy back into the wing's oscillations until it all falls apart. To do this you add weights forward of the hinge somewhere.  (Hold a piece of plywood by the edge in your hand and wave your hand back and forth.  The surface wants to "trail" behind your hand movement because it's center of gravity is away from where you're holding it.  If you were able to hold the piece near the middle at its center of mass, it won't do that).
A metal skinned surface is heavier than a fabric one, and therefore requires a heavier mass balance, so the overall weight gain is substantial because adding weight aft of the hinge requires a balancing increase in front of the hinge.  But later on as the speed got up there, the fabric covering itself became a problem and designers just went with metal and lived with the higher weight.
Answer: A metal control surface can also sustain some small arms fire without disintegrating -- aircraft with metal rudders and elevators used to routinely come home with bullet holes in those surfaces.
The real reasons wood and fabric surfaces might have been preferred (though they weren't always; several designs had all-metal control surfaces) are the classic reasons for everything in aviation: cost and weight.  In the late 1930s, when many of the aircraft used in WWII were designed, it was still possible to make a wood and fabric structure, especially a control surface (as opposed to a wing), that would give the needed performance and strength and come in lighter than an all metal one, and frequently at lower cost in volume manufacturing.
As performance specifications continually crept up (higher speed, higher loading, more vibration from a larger engine, etc.), metal surfaces gained the advantage.  They could ultimately be stronger than wood and fabric, hold their surface shape over a broader speed and pressure envelope, and as noted, wouldn't disintegrate if they took a few bullets -- in fact, they were usually more durable than wood and fabric, because metal is less prone to tears and splintering.
Answer: Fabric covered control surfaces on otherwise all metal aircraft were rarely wood, but rather metal, and it was done to reduce weight, which is particularly important when it comes to the control surfaces, as heavier control surfaces translate into heavier stick movements.
Here is the rudder from a Harvard I trainer, which was fairly typical for any control surface - the ribs are stamped aluminium sheet, and the structure was riveted together, and then covered in fabric which is sewn to the ribs.
Earlier types often used steel tubing, but that had become fairly rare on military aircraft in WW2, aside from some smaller trainers.
Answer: @MeatballPrincess welcome to Aviation StackExchange, and interesting question. I don't feel the answers so far are completely inclusive of all the factors, so I'll include my interpretation of the answer. Firstly, some other variables you could keep in mind was the US's manufacturing capability during WW2 compared to countries that fielded many wood-skinned aircraft, such as the RAF. I'm not completely sure where you got your information that the US preferred wood and fabric over metal during WW2, as we had few shortages of metal and as I will explain, the performance and application of these fighters simply negated any real reason to use anything but. However, metal is expensive, and the UK's situation was too urgent to take the money and time to develop newer metal skinned prototypes. If I recall correctly balsa wood was the main skin and chemically treated stressed fabric was the most common fabric used in aircraft skinning. Of course, planes such as the Spitfire and others are exceptions, but we see fabric and metal making up a large portion of the skin on the most numerous and resource intensive applications i.e. the Hurricane and especially the Mosquito.
To address your point on durability under small arms fire, you could probably use common sense to identify the fire hazard of wood, but again it was treated to be fire-resistant (obviously) and the two materials (aluminum vs wood) have various pros and cons. As a skin, these materials just cover the frame and slightly protect the interior, of which the more vital component will be further shielded with steel plating. When bullets or cannon shells blow holes in the skin, metals such as duralumin retain some measure of rigidity and unless those shells were loaded with some seriously hot chemicals, won't burn. Wood and fabric on the other hand can be easily set off by competent incendiary rounds and will continue to burn away the aircraft's aeronautical properties. The metal used by the US was mainly duralumin, which was an aluminum-copper-magnesium alloy with a density of 2.78 g/cm^3, compared to balsa wood which is 0.16 g/cm^3. Obviously, wood and fabric (which is even less dense) are lighter than metal. However, duralumin is simply just better for fighter aircraft, or any machine with combat application. It resists crumpling and wrinkling (a huge issue for fighter planes back then) to hundreds of miles per hour greater than fabric ever will, and wood has issues two-fold: it can't be easily used in naval theaters as water rots even treated wood faster than it rusts metal, and it burns. As a result we see that the US had pretty much 0 non-metal frame and skin fighters, bombers, or reconnaisance aircraft stationed on aircraft carriers or anywhere for that matter. John K already answered the aerodynamic reasons for choosing metal, but I don't think any of the other answers explains why the US actually didn't use wood. It was duralumin for almost all of their fighters from the onset of war to today. Simple as that.
Answer: Primarily weight and manufacturing simplicity.  The fabric covered structures worked well for those applications and could be manufactured at a minimum of cost and complexity.  It had nothing to do with protection against enemy fire - most all metal aircraft are thin skinned and vulnerable to even small arms fire.


Valuation of the minimum guaranteed return that (some) pension funds provide - how would you do it?

Question: Let's say a pension fund guarantees an annual return of at least 5% to their customers/investors, such that the investors face a payoff like the one of a call option (no downside). For this guarantee the investors pay a premium. From the fund's point of view, this guarantee is like a short put as they only face a downside; if the return is less than 5% they have to withdraw funds from a reserve account to cover the loss, while if the return is more than 5% the investors receive the excess return. For this short put the fund requires a premium. So, how should one perform a valuation of this short put, i.e. what would the fund have to pay to be completely hedged? In my view, this has to be the value of the minimum guaranteed return. However, as the underlying asset is the portfolio consisting of stocks, government bonds, corporate bonds, and investments in other funds, using option pricing theory (Black-Scholes, binomial pricing) is not so straightforward.
Answer: I'm not sure if this truly belongs in quantitative finance, but as an actuary, I can't resist responding. The answer to your question literally fills thousands of pages of regulations, research papers, best-practice articles, and study materials.
Pension funds are VERY exotic options. They're not just puts. They're puts tied to mortality, employee behavior, and statutory law (early retirement, employment longevity, ERISA, etc.).
For instance, statutory law allows public plans to discount their expected future cashflows at the rate of return expected on their backing assets. Actuaries and investment analysts set these discount rates based on the basket of securities the pension holds. Private plans discount cashflows based on the AA corporate bond yield curve no matter the backing assets, but again, these bear a spread and risk premium over the risk free rate. The reason I bring this up is because pension liabilities (valued with a risk premium) will NEVER move with your risk-neutral hedging assets. You can get close if you match the duration of your pension obligations with a basket of AA bonds. That's called Portfolio Immunization, but even then, it's not exact, and it's not what you're talking about.
Ignoring the discount rate, you're on the right track with how to think about one type of risk present in pension plans: market risk. To value the embedded put option in a pension guarantee, you'd have to model out thousands of possible growth paths for your various investments with average growth set to your risk-free term structure using Monte Carlo scenario generation. Then, taking into account all the actuarial risks associated with pension plans under each scenario, discount the projected payout in scenarios where the pension assets cannot cover future withdrawals.
I would suggest looking into actuarial forums for further exploration.