is a voltage regulator required for atmega328p when powering from boost converter at a set voltage?

Question: I know that linear voltage regulators are more accurate at holding the required voltage but the boost converter i am using seems to keep a pretty steady one. the voltage will of course be within the chips requirements.
what would be the main drawbacks of not using one?
Answer: is a voltage regulator required for atmega328p when powering from boost converter at a set voltage?
No it is not.
The ATMega is "just" some logic circuits in a chip.
So is the CPU in your PC and in your smartphone. Both of these are powered directly from switched regulators (usually buck converters but that doesn't matter that much) and they work fine!
As long as you keep the supply voltage of the ATMega chip within the specified limits (see the manufacturer's datasheet, from my memory it is 1.8 V to 5.5 V) then it will work as long as there is not too much variation (ripple) on the supply.
To keep the ripple in check, any boost, buck and linear regulator has at least one decoupling capacitor across its output. The ATMega chip also needs it's own decoupling capacitor. It is good practice to place at least one near each supply pin.
The accuracy of the supply voltage is not that relevant. The logic will work just as well at 3.456 V as it will on 3.3000 or 5.0000 Volts.
The only exception can be if you use the build-in ADC of the ATMega. This ADC can use the supply voltage as its reference voltage. If the supply is not accurate then the ADC's output data will not be accurate either.
There is a build-in more accurate reference for the ADC that can improve this.
You can also use an external reference voltage if you like.
Also if you would use the PWM output function, filter the PWM signal and want it to be accurate then also it will be as (in)accurate as the supply voltage.
But in general, if you need this then you would know and take precautions.
Oh and there is no reason to assume that switched regulator (boost or buck) are in any way less accurate than linear regulators. It depends on the model (chip, circuit) you're using and if you calibrate it or not (measure the voltage with a known accurate meter and then adjust to the right voltage). Both linear and switched can be as bad or good as the other.
Comment: @marcelm And since we're nit-picking, there is also a **brown out** detection on the ATMega which has a threshold voltage setting which resets the chip if the supply drops below a certain value. For common Arduinos it is often set to 2.7 V while the chip can reliably work at 1.8 V if you keep the clock frequency low enough. I have a reprogrammed Arduino here set to the lowest brown-out voltage so that it can run down 2 AA cells down to below 2.0 V which increases battery life.
Comment: "_The logic will work just as well at 3.456 V as it will on 3.3000 or 5.0000 Volts."_ - Not if you want certain clock speeds, it won't ;) For example, at 2.7V, the 328P only guarantees reliable operation at 10MHz (see Electrical Characteristics > Speed Grades in the [datasheet](http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-42735-8-bit-AVR-Microcontroller-ATmega328-328P_Datasheet.pdf)). More generally, there will be a lower bound (determined by clock speed in this case), and upper bound (determined by what the transistors can tolerate). Stay within the bounds, and you're fine.
Answer: If you just have an all digital circuit, there are little drawbacks (some ICs do not react very well to voltage ripple, but those can be fixed with a RC combination on the supply usually).
One thing which might be an issue is also the ramp up of the voltage for the chips. You should make sure it starts fast enough for all the chips. This can be improved by the linear regulator, but there are also other ways to accomplish that (voltage monitor).
If you are planning on using the ADC (mixed analog and digital design), you might want to evaluate if the readings are within your required range of noise. Even then you can use the boost converter to power the digital part and the linear regulator for the analog one.
Answer:
One thing which might be an issue is also the ramp up of the voltage for the chips. You should make sure it starts fast enough for all the chips. This can be improved by the linear regulator, but there are also other ways to accomplish that (voltage monitor).

I would also enable the Brown Out Detector in the microcontroller. That will keep the chip in reset state until the power supply voltage gets high enough. There are a couple of voltage levels that can be selected: Off, 1.8V, 2.7V, and 4.3V typical, +/- 0.1 to 0.2V.


AJAX calls action for a partial?

Question: I have a page show.html.erb with a corresponding action 'show'. Lower on the page, a partial is loaded called _filter.html.erb which contains undefined instances (so basically, on the initial load, nothing is displayed there).
In the show.html.erb, I have a form that uses AJAX and submits to an action called "filter" which is supposed to create some instances for use within the _filter partial (so now, the _filter partial within show will have some content).
But when i submit the form, it says Template is missing  Missing template results/filter.
But what it should be doing is staying on the same current template (show.html.erb) and just run the filter action and update the partial _fitler.
Any suggestions?
UPDATE
Following some things i found online, i made a file _filter.js.erb withing the views/results directory (same dir as show.html.erb and _filter.html.erb):
$("filter").update("<%= escape_javascript(render("filter"))%>");

But it doesnt seem to be doing anything..
Answer: By rails convention if you use the name _filter then you should put this file in shared folder.
So it's should be shared/_filter.html.erb
Comment: Why? Because its a partial or bc the name filter?
Comment: Because it's a partial. The sign '_' means that rails should look for this file in 'shared' folder.

AJAX calls action for a partial?


Were marriage certificates, granted after banns, recorded?

Question: In the groom's parish of Bagillt, Flintshire, Wales, the marriage banns was recorded. At the bottom it says "Certificate granted Sept 14th 1835". Would a copy of that certificate have been recorded? What would the certificate say? Is there value in searching for it?
The marriage was recorded in the bride's parish of Llanferras, Denbighshire, Wales but I can't find record of the banns. I'm hoping to find a marriage record which mentions the names of the groom's parents and the certificate mentioned in the banns from Bagillt is my next idea.
Comment: My usual approach would be to find the couple in the censuses - there are candidate couples in Hope, Flintshire in the 1851 and 1861 census - and then look for candidate baptisms in their areas of origin. Unfortunately, he claims to be born in Hope in the 1851 and Gresford (Denbighshire) in the 1861. She's born in Hope in both cases, so is simpler. My *inclination* is that I'd prioritise looking for Charles (*if* it's the right family) in Gresford on the basis that in 1851, someone wrote "Hope" for everyone.  You may well have done this already and discovered multiple candidates for Charles?
Comment: @AdrianB38 I have been down that route. We have two candidate baptisms.
Comment: JustinY, have you tried tracing the individual in each of those baptisms forward to try to eliminate one or both of them?
Comment: @JustinY: "We have two candidate baptisms". I was afraid of that. I thought it was worth indicating my methodology because I wasn't sure how much experience you had of our records of that era but, as I did a rough search myself, I began to suspect that you'd already been down that road. And looking at my map, it also seems like all the candidate's parishes are pretty much adjacent. Oh dear...
Comment: @ColeValleyGirl We might have, once. This is the sort of problem person we come back to every 6 months. I think I'll try it again though.
Answer: There is nowhere that a copy of that certificate would have been recorded.
Whether or not parents names were recorded in Parish Marriage or Banns Registers in England and Wales before 1837 varied widely -- there was no requirement to do so, so it was dependent on the whim of the parish incumbent.  From the start of Civil Registration in 1837, father's names and occupations were recorded but even today there is no requirement to record details of mothers.
Comment: I would *guess* that the sole function of that certificate is just to certify to the minister at Llanferras that the banns had been read at Bagillt. Hence there would be no need for detail above and beyond that written in the record of the banns.


How do I send individual links to collect data in Cognito Forms

Question: I want to gather information and pictures from 100 college alumni.  How can I do this in a way where I can send individual links to each alumni member?
Answer: Here is the process to accomplish this in Cognito Forms:

Create the alumni information form with all of the fields you want to collect, including a file upload field for the pictures.
Under Form Settings, enable Entry Sharing to allow you to send secure edit links to form entries.
Customize the entry sharing email template to ask the alumni to fill out the form via the provided link.
Under Submission Settings, enable Save & Resume so you can create incomplete/partial entries containing the basic information for each alumni without filling in all of the required fields.
Under Entries for the alumni for, create entries with basic information (like name and email address) for each alumni.  Click Save (not Submit) to save the entry as incomplete without validating all of the required fields.
For each entry, click Share, select Send an Edit Link, select Link Expires - When Submitted, then click Send.

This will send a personalized email to each alumni, with a partially prefilled personalized form that they will then be able to submit with the required information.
Here is what the entry link sharing experience looks like when managing entries:
Comment: Jamie - Thank you.  Does this mean, I have to take the $10/month service, until I want to hold this support for the site?
Comment: Yes, entry sharing does require a Pro plan subscription.


Can you wear a cloak of charisma and a shadow veil at the same time?

Question: The Libris Mortis description of the shadow veil item (p76) says it precludes wearing any other kind of armor. Does this include a cloak of charisma or is a cloak not considered a kind of armor?
Answer: A shadow veil is a robe-slot item, which interferes with magic armor but not with shoulder-slot items like cloak of charisma. Note its presence in the Undead Armor section of Libris Mortis. See Magic Items on the Body for more information on the various slots and how they are filled:

Many magic items need to be donned by a character who wants to employ them or benefit from their abilities. It's possible for a creature with a humanoid-shaped body to wear as many as twelve magic items at the same time. However, each of those items must be worn on (or over) a particular part of the body.
A humanoid-shaped body can be decked out in magic gear consisting of one item from each of the following groups, keyed to which place on the body the item is worn.

One headband, hat, helmet, or phylactery on the head
One pair of eye lenses or goggles on or over the eyes
One amulet, brooch, medallion, necklace, periapt, or scarab around the neck
One vest, vestment, or shirt on the torso
One robe or suit of armor on the body (over a vest, vestment, or shirt)
One belt around the waist (over a robe or suit of armor)
One cloak, cape, or mantle around the shoulders (over a robe or suit of armor)
One pair of bracers or bracelets on the arms or wrists
One glove, pair of gloves, or pair of gauntlets on the hands
One ring on each hand (or two rings on one hand)
One pair of boots or shoes on the feet

Of course, a character may carry or possess as many items of the same type as he wishes. However, additional items beyond those listed above have no effect.
Some items can be worn or carried without taking up space on a character's body. The description of an item indicates when an item has this property.

Emphases mine—notice how a robe or armor is separate from a cloak or a cape.
Furthermore, there are rules for combining magical items so that they can be used at the same time. This usually incurs a price premium of 50% for each effect after the first, but Magic Item Compendium specifies that certain bonuses—including enhancement bonuses to Charisma, as found on the cloak of charisma—can be combined with other items at no extra premium, just the sum of the two costs.
Answer: First of all, be aware that D&D 3.5e has a thing called item slots. Only the first magical item worn in each slot works.
The three slots for what you would call the torso in plain language are the Shoulder slot (cloaks and capes), the Torso slot (vests and the like) and the Body slot (armors and most robes you wear over a vest, including the Veil).
Armors are worn over the whole body, and this prevents you from using two armors at the same time, but due to how item slots work it could still be possible to wear a nonmagical armor (still providing a bonus to your AC) and the Veil at the same time, weren't it for the wording of the Veil specifically preventing it. Basically, the authors want you to make a choice between AC and the benefits of the Veil.
Now that you can see that the wording is only there for enforcing some regulations over the Body slot, it goes without saying that no, it does not interfere in any way with the cloak you want to use.
Comment: @HeyICanChan On page 214 of the *DMG*, under "Magic Items on the Body;" you'll find a reference in the second-last paragraph in that section. It's also on page 218 of the *Magic Item Compendium*, under "Body Slots;" It's the last sentence of the first paragraph after the list of slots and what can be worn on them.
Comment: @HeyICanChan It's the first item; If it was the last, it'd be an easy way to remove cursed magic items. That said, there is a rarely-used exploit where you can quickly change which magic rings you count as wearing by taking off rings you put on earlier.
Comment: (While I know that's largely inconsequential to this answer's accuracy, is it *really* the *first* worn magic item in any slot that has an effect? I thought it was, instead, the *last* worn magic item in a slot. For example, I thought that a *second* magic amulet donned after the first magic amulet obviates the *first* magic amulet rather than the first magic amulet obviating the second!)
Comment: @GMJoe That… makes a lot of sense, actually, but I'd still like a citation from somewhere to reassure me of it. ([Some cursed magic items can just be removed](https://www.systemreferencedocuments.org/resources/systems/pennpaper/dnd35/soveliorsage/magicItemsICA.html#amulet-of-inescapable-location) once the wearer realizes the cursed item's effect, though you're right that [most can't](https://www.systemreferencedocuments.org/resources/systems/pennpaper/dnd35/soveliorsage/magicItemsICA.html#boots-of-dancing). But a typical biped'll be awfully uncomfortable wearing two pairs of even magic boots!)


How do I eliminate one 3 way switch and replace it with a single pole switch?

Question: I have knob and tube wiring in our 110 year old house. There are 2 3 way switches that control one light in the house and also supplies power to the garage. There are 4 overhead wires going to the garage so I am not sure if the 3 way in the garage has the main hot wire going to the 3 way or if it is in the kitchen 3 way. How can I tell which one is the main feed and then replace the kitchen 3 way with a single pole switch?
Comment: Got a mains tester screwdriver? That should be pretty enough.
Answer: A modification of longneck's process: (not enough rep to comment)

Set the switches so the light is on.
Turn the breaker off
Remove the garage switch; use a test meter to figure out which leads the switch is connecting.  Connect those two wires permanently.  You are removing this switch from the circuit.  Cap the other wire.
Remove the other switch; use a test meter to figure out which leads are connected by this switch, hook them up to a single pole switch.  Cap off the remaining one.

To figure out where the power really flows in this circuit, you have to power this up safely, with the terminals exposed, and use a neon tester figure out which is hot, when the switch(s are) is off.
Answer: You can cheat.

Put the kitchen switch in the position that you want to correspond to "on".
Flip the garage switch so the light is on.
Turn off the breaker.
Pull the garage switch out, being careful to not flip the switch. There will be one wire on one side, and two on the other. Connect the single wire to the wire on the other side corresponding to the position of the switch. Cap the other wire off.
Pull the kitchen switch out, being careful to not flip the switch. Similar to the garage switch, connect the new single pole switch to the single wire and the wire that corresponds to the position of the switch. Cap the other wire off.
Comment: This method is reliant on a switch made by a specific manufacturer. Not all 3-way switches have the traveler terminals on one side of the device. See [this switch](http://i.stack.imgur.com/l2T4n.jpg) for example.


CDC - I cannot disable that on the second instance

Question: I have change data capture enabled for most of the tables in one of my databases. Database is hosted on SQL Server instance with version 2016.
I have some testing to be done, so I wanted to restore backup of that DB in my test environment. But I am really struggling with that (I am not sure what I am doing wrong).
Firstly I tried to restore that as any other DB. The restore is working fine... till the very end when is returning the error that it cannot drop CDC tables because it's not enabled. So I added keep_cdc keyword to restore command and it finished successfully. As I do not need CDC at test I wanted to disable it... but it's in a weird state:
exec sys.sp_cdc_disable_db returns error:

Could not update the metadata that indicates database DB is not enabled for Change Data Capture. The failure occurred when executing the command 'drop user cdc'. The error returned was 15284: 'The database principal has granted or denied permissions to objects in the database and cannot be dropped.'. Use the action and error to determine the cause of the failure and resubmit the request.

So... error says that CDC is disabled.. but when I run sys.sp_cdc_enable_db I got an error:

Database 'DB' is already enabled for Change Data Capture. Ensure that the correct database context is set, and retry the operation. To report on the databases enabled for Change Data Capture, query the is_cdc_enabled column in the sys.databases catalog view.

And is_cdc_enabled indeed shows 1 for that DB. So I wanted to to use GUI. It also shows that cdc is enabled:
[![enter image description here][1]][1]
But, when I change that to 'False' after ok I am getting error:

Change tracking is enabled for one or more tables in database 'DB'. Disable change tracking on each table before disabling it for the database. Use the sys.change_tracking_tables catalog view to obtain a list of tables for which change tracking is enabled.

And now the tricky part that I do not understand at all. select * from sys.change_tracking_tables returns 30 tables. While sys.tables I had > 100 tables with is_tracked_by_cdc  not equal to 0. I executed sys.sp_cdc_disable_table  procedure for each such table select * from sys.tables where is_tracked_by_cdc <> 0 and as a result all these tables have is_tracked_by_cdc equal 0in sys.tables... but sys.change_tracking_tablesstill returns30tables and runningsys.sp_cdc_disable_table` against them does not change anything. As a result I cannot disable that feature on database level as well.
Could you please advise how can I get rid of CDC completely at such copy? (I was trying dropping all CDC object as well but without success)
Answer: Check which permissions that user has granted and remove them:
select * from sys.database_permissions
where grantor_principal_id = user_id ('cdc');
The error saya that cdc user ran grant or dey statement to another user (someone logged in with it, and ran some grant or deny statement)
After removing it, try disable cdc or try restore without keep_cdc


installing emacs on CentOS

Question: I installed VMware and I have centOS installed in it and I'd like to install emacs on it but I don't find any source which has the tar file for that. I either find it for Linux or Solaris but when I tried installing the tar file given for Linux on VM it isn't installing. Can anyone give me the source where I can find the tar file for emacs that I can install on VM and also instructions on how to install it? I find using emacs easier than VIM. And what is the difference between Linux installed on disc and installed on a VM?
Comment: why can't you just `yum install emacs`?
Answer: emacs is in the epel repos. Open a terminal and run:
sudo yum install epel-release
sudo yum install emacs

Comment: sudo yum install epel-release ....... "already installed and latest version"
sudo yum install emacs ....... "no package emacs available"
Answer: You can get source at: ftp://ftp.gnu.org/pub/gnu/emacs/
Then use these commands.
tar -zxvf emacs-VERSION.tar.gz

cd emacs-VERSION

./configure

make

make install

Source: https://www.gnu.org/software/emacs/manual/html_node/efaq/Installing-Emacs.html
Answer: Answering the second question,
When you install Linux on disc, you are going to use the kernel for the specific hardware that your machine has with the OS from that distro, if you use a VM instance, there should be a mid-layer between your machine (hardware) and the OS, this could be using extra modules from a kernel (like VMWare and Virtualbox) or creating a special kernel that has no proper OS like (Xen).

There is a performance difference in both operating system and operating system as VM, but it should be minimal unless you need to do some heavy processing.

installing emacs on CentOS


BXslider and making call for active LI on onAfterSlide callback

Question: Working on a slider built off of bxslider.js
I require a callback that sets the LI to active on slide and removes the active class off the previous LI that it was just on.
I've gotten a very crude example working but lack the JS knowledge to write a script that detects onAfterSlide the active slide, tells the corresponding LI to be active and then removes any active state from any previous LI. The onlcick callback is working just fine, the onAfterSlide needs some love.
Somewhat working example: http://diveidc.com/slider.php
Here I have really crude attempt to get the next LI to become active but can't remove the previous LI active. The basically go all red since they all get assign the active class, as the slide goes through it's loop I need to only assign the active class to the LI that corresponds to the current slide. ie: slide1=li1 active, slide2=li2 active etc.
Source of the BXslider http://bxslider.com/options
Answer: <code>onAfterSlide: function(active) {
   $('someul li').each(function() {
      if($(this).index() == active)
         $(this).addClass('active');
   });
}
</code>
I haven't tested this, so use on your own risk :)


Why does Drupal use the database for the cached data?

Question: Why Does Drupal put the cached data in the database? It's hard too understand it, because the database can easily cause performance bottleneck.
Answer: The question that asked here is not whether the database cache can be replaced by something else, but why Drupal caches database information in the database. A reason that is not mentioned here is that although database information is again cached in the same database, it is not cached in the same format. The original data, such as node information or theme information, is stored in a kind of normalized form, which makes it easy to edit and query data. The cached values are stored in a way that reduces the amount of processing needed to display a page.
Let's say a page view consists of the following simplified steps:

Fetch information from database
Manipulate information to make it suitable for display
Display the result

Now Drupal stores the result of step 2 into the database, so on subsequent page views, steps 1 and 2 do not have to be executed. This saves time and processing power. When the original data changes, the cache needs to be cleared.
Comment: I have added that it saves time and processing power, thus giving the reason why caching in the database is useful.
Comment: A good, though this answers how, not why
Comment: You could cache the same thing else where. It's not unique for the database to cache something ready for rendering. That's exactly what Varnish does, only a lot faster, since no processing at all is needed.
Answer: Drupal core comes out of the box with a good caching system that will handle low level usage. Using the database as cache, you could easily create a site with hundreds/thousands of daily visitors, which is enough for many. This is a good default, as it's easy to setup, but more advanced caching strategies for high performance are supported:

For both Drupal 6 and 7 there are modules to improve caching by using memcache instead the database for some of the caching.
For Pressflow 6 and Drupal 7 core you can setup external cache like Varnish.

So Drupal really has a lot of caching possibilities, but in order to use the more advanced for high performance, you need to do some extra work. This will also require various server setup anyways. But making the default easy to use really is preferred.
Answer: Fetching cached data from the database is easy and fast enough because they are simple SQL requests. Also, most of the results are cached in memory by the SQL caching system.
There are also other caching system, but they are not as good as database for a default caching system:

File system: you have to deal with data coherence, file permission, file lock, file management.
Memory: is faster than database, but you need extra setup. Thus this one should not be the default caching system.
Comment: Nice point there, the first answer which explains why the default behaviour is default.
Answer: Well in fact the drupal cache system is pluggable in drupal6 and drupal7,
which means that you can put any kind of caching system behind it.
By default drupal uses a database based caching system, but you can replace it for example
with the memcache module with a memcache, which scales much better then the database for the cache.
If you want you could even write a file based one, which will probably be must slower.
Answer: A very simple explanation is that it provides a caching interface which improves performance which, by default, doesn't add more layers to a Drupal site. Other caching mechanisms may be better or faster, but they would introduce additional requirements which would not be needed for many Drupal sites.
Luckily, the caching system can be swapped for those who need it.


Problem running iPhone application on iPhone from Xcode (and in Instruments)

Question: I have a problem running one application on the iPhone from Xcode (or Instruments).
When I try to run the app I get the error message Failed to upload XXX.app in the bottom left corner of Xcode. The strange thing is it actually uploaded the app to the iPhone but it doesn't start it (after this I can start the app by hand on the iPhone).
So without being able to start the app from Xcode or instruments I have no chance of debugging/performance testing.
Any advice on what might be going wrong here?
The iPhone console shows me this:
Thu Oct  1 14:25:18 unknown mobile_installationd[1976] <Error>: 00808e00 install_embedded_profile: Skipping the installation of the embedded profile
Thu Oct  1 14:25:23 unknown SpringBoard[25] <Warning>: Reloading and rendering all application icons.

Other applications work fine. I've tried this on two iPhones (both 3.1) with the same result. I am running Xcode 3.2 on SnowLeopard.
Regards
Answer: This happened to me as well (more than once). I ultimately had to restart Xcode to resolve the problem (after verifying the code signing settings were correct, the provisioning profile was installed, etc..).
Answer: I had the same problem and restarting Xcode solved it. Of course I checked that the right provisioning profile was installed on the iPhone and that the bundle id in the project settings matched the provisioning profile.
Comment: I had exactly this problem today, and as you found, restarting XCode fixed it. This happened around the time I was regenerating Provision profiles multiple times by adding new devices to them.
Answer: It says it couldn't install the profile. Check thoroughly your code sign settings and verify after you build the application that the profile you used for code signing indeed the one you chose: go inside the package of the built application, find the embedded.mobileprovision file, open it with a TextEdit application, look for <name> tag and see the value. If the value doesn't match the profile you have set in your project, that's might be the reason for the problem.
Answer: Restarting Xcode solved the problem. While Xcode was running I downloaded a newer version of the iPhone OS via iTunes (v 3.1) and sync (but did not update) the iPhone. My current OS version on the device was 3.0
Maybe this helps.
Answer: Perhaps your executable name is set incorrectly.
Expand the Targets group, double-click your target, go to the Properties tab, and check the setting next to "Executable:"
In my projects, it's set to ${EXECUTABLE_NAME}
I think you can also check this in your Info.plist file.


Can physical spaces 'resist' certain sound frequencies?

Question: I whistle a lot, and I'm fairly decent at it. Recently I was walking up the stairs in a house while whistling. As I whistled, I found it difficult to hit a specific note in the song that I would normally be able to whistle. I found this strange, so I stopped in that exact spot on the stairs, and tried whistling that note. It felt as though there was some kind of resistance when I whistled that exerted pressure on the pitch either up or down to a different note at which there was no resistance. It seemed really weird to me, but I stood there for a few minutes testing different pitches, and it really seemed as though there was a certain pitch that didn't resonate well in that space, and not only that, but I felt some kind of pressure on the note that I was whistling to move to a different note. Is this kind of like the opposite of resonance? Or am I crazy?
Answer: This sounds like destructive interference interacting with your attempt at driving a resonance.
Normally when whistling or singing in the shower or a stairwell, certain pitches get nicely amplified by resonance. These room modes are standing waves where the pitch fits into an integer number of wavelengths between reflecting walls. The sound source corresponds to a pressure amplitude maximum, but if it is a quarter wavelength from the wall the reflected pressure wave will exactly cancel it. So at least in some places for each pitch there should be "dead" spots.
(An interesting question is why we rarely observe them, while shower singing easily finds resonances where our voices fill out well. It might just be that we unconsciously modulate the pitch to where it resonates rather than keeping the same pitch and moving.)
Answer: It could be possible that the produced sound echoes in the room and the echo makes destructive interference with the original sound. It would affect different harmonics differently however, so I recommend also trying to use a the same note an octave higher or lower to exclude this possibility.
Answer: Usually, the stair well in a house has fairly hard reflective wall surfaces and nothing much that would absorb sound energy. Therefore, there would be frequencies at which a strong standing wave pattern would be produced in the space.
If you were at a position where the amplitude of the standing wave was zero (called a "node") then you would experience more "resistance" if you tried to produce a note at that frequency. You can think of this in simple terms as the sound waves reflecting back from the walls and "cancelling out" your attempt to move the air when you try to produce a note, though of course in a complicated 3-dimensional shaped space like a stair well that is an over-simplified explanation.
This effect is very important in the design of musical instruments, where the sound waves are inside of tube of some fairly simple shape, rather than in an open space like the stair well. It is the basic reason why wind instruments "play" a single note when you blow them, instead of a continuous range of frequencies, and why by changing the geometry of the tube (by opening and covering finger holes etc) you can change the note that the instrument plays.


What Disney kit has part number 35347 with vines sticker on it?

Question: What Disney kit has part LEGO Cylinder 3 x 6 x 6 Half with Tower with vines Sticker (35347) on it? Have all the set in pieces but the manual has been lost so do not know which manual to look for.
Answer: Based on your description and the element number, the only set I found matching this description is 41154: Cinderella's Dream Castle


Windows 8.1 / iSCSI / Hyper-V Depedencies

Question: My workstation has Windows 8.1 and uses iSCSI for SAN storage, which is where the Hyper-V configuration and VHD files sit. When the workstation is booting up, the VM is not able to auto start because "The Virtual Machines configuration 037C33D6-433C-42AF-B51A-F7292A1FB2A4 at 'H:\Degas\vnix' is no longer accessible: The system cannot find the path specified. (0x80070003)." What dependencies do I need to configure to tell Hyper-V to wait until iSCSI is up and running before it starts looking for files on the SAN?
Comment: I would say none, the way your iscsi is configured looks wrong. As in: It is a standard setup to have vms on an ISCSI target.
Comment: I would agree, but possibly since this is not a server operating system, it doesn't put that much priority on iSCSI?
Comment: Posibly, but then seriously - no clue. This is why I just commented. Not using Hyper-V on a workstation here (although I really look forward to the time I have to, it is a great tool for developers FINALLY).
Answer: This Microsoft support article has the answer. You need to set the Hyper-V services to depend upon the iSCSI services if they are not already.
http://support.microsoft.com/kb/193888
You should also make sure that your iSCSI services are not set to use Automatic (Delayed startup) as discussed at:
https://stackoverflow.com/questions/11015189/automatic-vs-automatic-delayed-start
But like TomTom said, it sounds like you have not properly configured iSCSI and I would recommend redoing the steps required to configure your iSCSI initiator to work with your iSCSI target before attempting the steps above, because while these steps may offer a workaround to the problem you're experiencing they are not a replacement for having it properly configured from jump street.
Comment: I already had Hyper-V setup to depend on iSCSI. Hyper-V showed errors because it could not access the configuration files, which were on the SAN. I changed Hyper-V to start on "Delayed startup" and that works. Not ideal, but as long as I don't need to manually start the VM's, I am happy.

I didn't have this issue when I was running just Windows 8...


Adding more than one folder at once to the Music Library in Windows Media Player

Question: I was adding folders to Windows Media Player Music Library (via Manage Music Library) and since I have too many music folders, I wondered if there is a way to add them all at once to the Library. It will be a real time saver.
Answer: To make it clear: The Windows Media Music Library is actually the Music Library of your Windows system. Apart from using the GUI that comes with Windows, you can also use alternative command-line tools to add a folder to a library.
Here is an article that lists some of such tools: http://www.grimadmin.com/article.php/creating-modifying-windows-7-libraries (download shlib and slutil))
As an example, you can add a folder to the Music Library using shlib like this:
shlib add "%userprofile%\AppData\Roaming\Microsoft\Windows\Libraries\Music.library-ms" "C:\Files\Audio\01\Skrileks"

Using slutil, it would look like that:
slutil addfolder Music "C:\Files\Audio\01\Skrileks"

To add more than one folder, you can create and run a batch file.
Answer: I found an easy way to do it - choose the folders you want to add and drag and drop them in the Folder View of the Music Library.


Alt-PrtSc-K not working

Question: Alt+PrtSc+K is not working on my machine.  I'm currently using Ubuntu 14.04.1 LTS.  The shortcut used to work on older Ubuntu releases (whose purpose was to kill the display server).  Any suggestions?
Comment: That shortcut used to kill the X server.
Answer: run sudo dpkg-reconfigure keyboard-configuration and when you see this window just select "yes".

And the next time use Ctrl+Alt+Backspace  to kill X.
Comment: Thanks for the answer, but according to the Magic SysRq keys the Alt+PrntSc+K should "kill all processes on the current virtual console".  I'm wondering why this is not the case.
Comment: @KasiyA As far as I've read myself through lots of documentation, Ctrl-Alt-Backspace is NOT the same as Alt+PrtSc+K! While the former is only intended to shut down the _X server_, the latter will operate on a level much closer to the kernel, i. e. even cause some problematic drivers to get reconfigured. Hitting the SysRq key combination too often (in despair, because things went really wonky on here) even caused a __kernel panic__ here and there, whilst this has never happened with Ctrl-Alt-Backspace to this day.
Answer: By default, in Ubuntu 14.04, the Magic SysRq keys are disabled.  To enable the Magic SysRq keys open the file /etc/sysctl.d/10-magic-sysrq.conf and change the line
kernel.sysrq = 176

to
kernel.sysrq = 1

Then reboot your Linux box.
Answer: In addition to what ramon wrote, here's a solution to (re-)enable Alt+PrtSc+K even without reboot!
I found it all by myself, as the documentation about it is abysmal (to say the
least).
Here on Lubuntu, the original value in /proc/sys/kernel/sysrq is 176. This caused SysRq+K to be completely disabled.
To understand this, you have to know a little about bits, bit masks and hexadecimal numbers:

176 is $B0 in hex, or 1011 0000 in binary.

To make Alt+PrtSc+K work, the second bit must be set:

1011 0000  OR  0000 0100 = 1011 0100

This will be $B4 in hex or 180 in decimal.
So here we go:
$ sudo sh -c "echo 180 > /proc/sys/kernel/sysrq"

The SysRq combination should work perfectly now, and without requiring reboot nor logout.
Comment: When you say "second bit", shouldn't it be 1011 0000  OR  0000 0010 = 1011 0010?

Alt-PrtSc-K not working


Apache - extremely slow initial handshake (SSL enabled)

Question: I have a problem with Apache server. The initial SSL handshake takes about 5-7 seconds which is horrible. After that the response time is in miliseconds - but the messages must be sent right after the first one or the handshake will be done again after a few seconds of inactivity. Is there any way to speed it up with Apache configuration?
Answer: This is with some Linux distro, right?
Is this server mostly idle? Perhaps Apache is shoveling randomness from /dev/random. That can be sometimes very slow, since /dev/random requires "real" randomness; stuff like moving the mouse, using the keyboard and network traffic gather the entropy. If the kernel entropy pool is nearly empty, processes requiring randomness tend to stall for a (long) while.
Should this be the situation, cat /proc/sys/kernel/random/entropy_avail should be near zero during SSL handshake.
You may switch the randomness source to /dev/urandom by using SSLRandomSeedApache directive, but be warned, this is theoretically not as secure as /dev/random.
Other solution is to use daemon like rngd (available from rng-tools package in many Linux distros) which fills up entropy pool.
Comment: No change with `/dev/urandom`. I don't have `rng-tools` and `tcpdump` from the post below available and because I'm not the server's admin I can't install it.
Answer: Besides what Janne Pikkarainen said, check also if the server is not doing a DNS reverse lookup for SSL requests. Run a tcpdump -pi eth0 port 53.


Data Driven Coded UI Testing in Visual Studio

Question: I am curious about an issue in Coded UI Testing. For example I created a button named Button1. I did assertions and everything is fine. Then I changed this button's name to Button2. Now, do I have to write my assertions again or is Coded UI Test can suit in every different name change. Notice that I am not doing any input or parameter changes, I am just changing user interface. Thanks for your replies.
Comment: what @AdrianHHH said, don't ever change the code in UIMap.cs file as it will be overwritten, i'm sure you already knew that though.

**Can I ask why you are changing a button's name**
Answer: You should be able to change the test code easily to cope with a name change like that. Open the UI Map file in the UI Map editor; ie double-click on the uimap.uitest file in solution explorer. In the left hand pane expand the method and select the action that clicks the button. That should open the relevant control in the right hand pane. Alternatively just find the control for the button in the right pane. View the properties of the button and click on the ellipsis of the "(collection)" value of SearchProperties or the FilterProperties. One of the items shown should be the old name of the button, just rename it there.


Why is the song E.P.M. by Dragonforce only on the Japanese release?

Question: The album Ultra Beatdown by the power metal band Dragonforce contains 11 total songs. 8 of those are on the main album, 2 are bonuses for the special edition and one of them, E.P.M., is only on the Japanese edition of the album. What possible reason could there be for doing such a thing?
Answer: Many bands adds bonus/special song on Japanese Edition.   Because almost albums firstly released on Japan. Especially Metal albums.


Nonlinear differential equation: $-y'(t)=\frac{1}{2}\alpha y(t)^2+y(t)^{3/2}$

Question: In a paper the differential equation $-y'(t)=\frac{1}{2}\alpha y(t)^2+y(t)^{3/2}$ occured. First of all, it does not satisfy the usual Lipschitz-condition. But there are probably weaker criteria. The solution was given as:
$$
y(t)=\frac{4}{\alpha^2}\left(1+W(-C_1 e^{-\frac{t}{\alpha}})\right)^{-2},
$$
where $W$ is the Lamber-$W$-function. Mathemica/WolframAlpha give nothing. I have not yet seen such a differential equation. How can one solve this?
Comment: Maple, though, finds an implicit solution. Plus, this is just a separable equation, which should be straightforward to solve.
Comment: It's usually a good idea when referring to Wolfram|Alpha results to link to them. In the present case, it seems you entered the equation either incorrectly or in an inconvenient form; when I enter it, I get [an implicit solution](http://www.wolframalpha.com/input/?i=solve+-y%27%3Da+y^2+%2F+2+%2B+y^%283%2F2%29).
Comment: Ouch, that is actually easy to see. I was so puzzled by this $W$-function. However, this was my input: [WA-Input](http://www.wolframalpha.com/input/?i=DSolve%5By%27%5Bx%5D+%3D%3D+1%2F2*a*y%5Bx%5D%5E2%2B%28y%5Bx%5D%29%5E%283%2F2%29%2C+y%5Bx%5D%2C+x%5D). To my knowledge, this is standard mathematica input.
Comment: The right side of the equation is locally Lipschitz (on $[0,\infty)$).  To avoid problems with negative $y$, replace the $y^{3/2}$ on the right side with $|y^{3/2}|$.  Since this modified equation satisfies the hypotheses of the existence and uniqueness theorem, and $y=0$ is a solution, the solution with any initial value $> 0$ will never hit $0$, so you don't have to worry about negative $y$.
Answer: The standard way to solve such a separable first-order ordinary differential equation is to divide through by the function of $y$ to get separate integrals with respect to $t$ and $y$:
$$
-\frac{y'}{\frac12\alpha y^2+y^{3/2}}=1\;,
\\
\int-\frac{y'}{\frac12\alpha y^2+y^{3/2}}\mathrm dx=\int1\,\mathrm dt\;,
\\
\int-\frac1{\frac12\alpha y^2+y^{3/2}}\mathrm dy=\int1\,\mathrm dt\;.
$$
Wolfram|Alpha solves the integral on the left (and shows steps if you click "Show Steps"):
$$\frac2{\sqrt y}-\alpha\log\left(\alpha+\frac2{\sqrt y}\right)=t+C\;.$$
With $u=\alpha+2/\sqrt y$, this becomes
$$u-\alpha\log u=t+C'\;.$$
Rescaling by $u=-\alpha s$ to get rid of the factor $-\alpha$, we get
$$s+\log s=-\frac t\alpha+C''\;.$$
Then exponentiating yields
$$s\mathrm e^s=C'''\mathrm e^{-t/\alpha}\;,$$
which is solved using the Lambert W function by
$$s=W\left(C'''\mathrm e^{-t/\alpha}\right)\;.$$
Then resolving the substitutions yields
$$y=\left(\frac2{u-\alpha}\right)^2=\left(\frac2\alpha\right)^2\left(1+s\right)^{-2}=\frac4{\alpha^2}\left(1+W\left(C'''\mathrm e^{-t/\alpha}\right)\right)^{-2}\;.$$
Comment: Thanks for this extensive answer!
Comment: @user13655: You're welcome!
Comment: @user13655 I think joriki has other standards for [extensive](http://math.stackexchange.com/questions/33094/deleting-any-digit-yields-a-prime-is-there-a-name-for-this/33303#33303)


"What is more", "What's more" too informal for academic writing?

Question: A coauthor of mine used the expression "what's more" in a scientific paper. My gut feeling was that this is not a commonly used expression in formal writing, but I could not find clear evidence for this so far.
Comment: There's nothing wrong with colloquial language in scientific literature. Science can be boring, but it welcomes good writing. It's legal and government literature that disregards colloquial language, as an ingroup move to keep outsiders from participating.
Answer: The formal academic equivalent is moreover:

in addition to what has already been said; furthermore

Or, indeed, furthermore

in addition; moreover

In general, I would avoid contractions in formal writing and "what is more" might come across as conversational. I haven't seen "What is more" in many academic papers, but "moreover" and "furthermore" are pretty well used. Google ngrams plots show this applies to other literature, too.
Answer: In general it is better to avoid contractions (like "what's more") in formal writing. But the uncontracted "what is more" is perfectly good English.


Why are (String[] args) not used as main method arguments in BlueJ?

Question: I've been using the Java IDE - BlueJ but I can't understand why the main method cannot be defined as
public static void main(String[] args)
in it. I get a syntax error when I try it.
Comment: And your question isn't clear. Show us what is going wrong, cause what you have mentioned doesn't make much sense.
Comment: Hi Srirag, to maximize the chances of getting a helpful answer, please use the Stackoverflow guideline for creating a minimum, verifiable, complete example. http://stackoverflow.com/help/mcve
Answer: Read the documentation, e.g. How do I call a main method in BlueJ, and how do I pass it arguments?:

How do I call a main method in BlueJ, and how do I pass it arguments?
You can call a main method in the same way as you call any static method in Java - by right-clicking on the class in the class diagram, and selecting the method from the pop-up menu.
When you call the main method from a class, you will see a parameter entry field that prompts you for the array of strings that the main method takes as a parameter.
By default, the parameter is
{ }

(an empty array, no parameters). If you want to pass, say, three parameters, from a command line you would write
java MyClass one two three

In BlueJ, you use the following parameter for "main" in the dialog text field:
{ "one", "two", "three" }

This passes an array of the three strings, just as the command shell does.
Answer:
As you can see, BlueJ throws no Syntax error if you define the main method as public static void main(String[] args). And why should it? That's the standard identity of the main method of a Java program. (If you still get a syntax error, then it'd be helpful if you can add a snap of the window in your question, like I've done in the answer, showing the compiler error.)
In BlueJ, you don't really run the program (just for saying): you just select the method to start executing from by right-clicking on the class Icon. BlueJ is a beginners' IDE. In real life, Java programs are not run the way you do in BlueJ. You can see that if you use IDEs like JCreator or NetBeans. Java programs are executed the way you execute any program on a computer. The .class file is run and the main method is automatically executed by the jre. But for the system to identify the main method, you have to define the main method this way - public static void main(String[] args) - this is the standard manner.
Instead of using BlueJ, if you compile and run a java program in windows cmd using the commands javac and java respectively, you will see the compile-time error saying "main method not found" if you write main() instead of main(String[] args). Below is a snap of what happens in NetBeans IDE when the main method is not defined properly.

And when the perfect program is run in NetBeans,


com.auth0.IdentityVerificationException: An error occurred while exchanging the Authorization Code for Auth0 Tokens

Question: I am trying to implement auth0 in a very basic spring-boot-application based on maven. This is the error that I get:

com.auth0.IdentityVerificationException: An error occurred while exchanging the Authorization Code for Auth0 Tokens

When running the original tutorial-project everything works fine. The error occurs only in my custom application. Basically I copied all the files from the tutorial-project into my application. Nevertheless I run into this error...
further down the exception I see a

com.auth0.exception.APIException: Request failed with status code 401: Unauthorized
Answer: Solved it:
The client-secret was wrong. Actually there is a space at the end of my client-secret, which I accidentally removed. Wow.


Unable to access Google services sporadically

Question: For the past 2 weeks or so now, I've been having issues with my ISP (I'm not in the US, so it's not Comcast or whatever).
Specifically, I often lose access to Google-related sites/services: the search engine itself, Gmail, Google Docs/Drive, Youtube, Google Keep are the ones I use most often. I've restarted my router multiple times already over the past couple of weeks. Same issue is encountered on my desktop (wired), laptop, iPad, phone (when connected over wifi) etc.
I know it's related to my ISP because (a) I've read some other users experiencing similar issues on social media; (b) if I tether to my phone's data connection, the problem isn't encountered.
I don't have a proxy server configured. I used to be using Google DNS but I've also tried switching back to my ISP's default DNS with no luck.
What's the best way for me to figure out what the issue is? (Preferably in a way that I can bring it up to my ISP so that they know specifically what they need to fix - talking to their customer service is a tedious experience so I've decided to figure out as much as possible before going back to them)
Screenshot of the error from the browser:

Sample tracert:

Pings seem ok right now (although if I leave ping -t running for a while, there's an occasional "Request timed out"):
Comment: Sounds like it's either your ISP or your router. You could try to factory reset your router or borrow another somewhere.
Answer: The issue is most likely a peering issue between Google and your ISP - Google direct traffic differently depending on your provider.
You can probably work arround the problem by using a VPN until your ISP has solved the issue.
Comment: It seems to have been resolved by itself (with my raising technical details at their customer service not actually helping), but it looks like you were correct. I was able to access the problematic sites when using Tor


specify a delay in camera upload

Question: Is there a way to specify a delay before my Dropbox app uploads photos into my Dropbox account.  I normally take a lot of photos, and delete many of it.  Dropbox app puts it onto my space before that. How do I specify a delay before it copies? Right now, I have to go to Dropbox and delete them again
Answer: The only way I think of would be to disable wifi and data while you take your photos and delete those you want to... Or enable the upload only on wifi, if you're not connected on wifi when you take your photos.

specify a delay in camera upload


Objective-C: Best way to package the contents of a file for Bluetooth transfer?

Question: In my program I am sending a file through an RFCOMM connection with a paired bluetooth device. I am having a problem with the receiving end writing the received bytes to a file. However, the receiving end may not be the root of the problem. It may be the way I am loading and sending the data intially in Objective-C. So, my question here is whether or not my method of loading and transmitting the file's data as bytes across an RFCOMM connection is acceptable. I am trying to avoid posting a lot of code because it will truly just get in the way. I would just like to know if it is ok or not to load file data into an array as I have for transferring, or if there is a better way to package the data?
Thanks in advance.
Data Types Involved
IOBluetoothRFCOMMChannel channel
NSData myData
Load File Code Snippet
<code>// Load file data into byte array.
myData = [NSData dataWithContentsOfFile: filePath];
int bytes[(int)fileSize];
[myData getBytes:bytes length:sizeof(int) * fileSize];
</code>
Transmit File Data Code Snippet
<code>// Loops create an int[] chunk array that holds an amount of data from bytes[].
// These chunks (packets) are sent using...
[channel writeSync: chunk length: 1000]; // Sends the packet.
</code>
Answer: You need to use the Archives or Serialization methods to convert the bytes streams into an architecture independent bytestream and then send over the RFCOMM channel, and at the receiving end convert it back
See Here


Collateral Damage with non-lethal playthrough

Question: I'm playing through the game non-lethally, and I'm trying to save Malik. It's hard enough non-lethally since all the non-lethal weapons are single-shot slow-firing poor-accuracy, but I've got a problem that when the bot lands and I EMP grenade it, the explosion kills one of the attackers. Does that mean that I no longer qualify for the achievement?
Comment: Do you get "Man down" for his death?
Comment: No. I got Man Down and the other non-lethal thing when I knocked him out to begin with, nothing when he blew up.
Answer: If when you target the body it has a Skull instead of zz's then yes it disqualifies you from receiving the achievement.
Try to draw enemies towards you (and away from the robot) before throwing the emp.
Answer: If enemy is hit by robot's self destruct explosion he is dead and it disqualifies you,but if he is hit by emp he will only be stunned and you still qualify as non-lethal.
Don't forget you can drag(E hold) stunned enemies away before the robot self destructs,you will have about 6 seconds.And be careful of exploding barrels.
Here's a video,it has some minor guidelines in description to help you.
Comment: Also, throwing a gas grenade at where the bot will land either knocks enemies out earlier (giving you more time to move them) or make them dodge away from the point of detonation (so that you don't *have* to move them later.) In addition, you can **throw enemies** too: Just start dragging them, aim, and "fire" to throw. Simple throws across flat ground and they live.


What is the minimum size of any exFAT volume?

Question: I'm trying to create a partition of 20GB size exFAT filesystem, but no partitioning software allows me (even Windows Disk Management). With 40GB it allows me, so I presume there is a minimum size for an exFAT partition. Somebody can reference any documentation explaining more about this?
Comment: Just now I successfully format 1MiB (1048576 bytes) partition into exFAT file system using build-in `diskpart` and `format` command line utilities.
Answer: On Windows 10, there was no problem formatting a 16 GB flash drive as exFAT. Admittedly, this is not a direct answer to your question, but at least it narrows the issue to either HDD vs. flash USB drive, or perhaps Windows version (which you did not state).

You might try to format using another version of Windows. exFAT is an MS proprietary format, so third-party tools might not work as well. Have you tried the tools at AlternativeTo?
Comment: "Admittedly, this is not a direct answer to your question" Then why have you not posted it as a comment?
Comment: I'm using a SSD drive which has GPT partition table and already has partitions on it. Using Windows 10.
Comment: @ Xavierjazz, Can't put an image in a comment.
Answer: Using the mkexfatfs utility on (Arch)Linux I can format a 84 KiB (86,016 bytes) partition with exFAT, but for 83 KiB (84,992 bytes) the utility errors out (ERROR: too small device (83 KB)).
On Windows I can't go below 1 MiB, because diskpart seems to only accept size arguments in MiB.


workload not availble on visual studio 2017 setup

Question: i use vs2017 with unity but now when io want to install it on new pc there is a message says: workload unavailable right now. required conditions are not satisfied. not win10 threshold number1 and number2 build number
Comment: This sounds like a troubleshooting problem you might want to take up with Unity/Microsoft technical support.
Answer: its all about windows Version.visual studio plugin for unity depends on new updates of windows. i just updated the windows and it worked.


How to Write a Short Story Collection?

Question: I plan on writing a collection of short stories. How should the manuscript be formatted? Can I write new short stories specifically for the collection. How hard is it to get published (I need someone to answer who has experience with this) I plan on writing a collection of short stories about a Venus where the tropes of the 1950's are its reality.
Comment: I wouldn't worry about the manuscript format just yet. Write your stories. Edit your stories. Try to get your stories published in journals. Then pull your stories together for a collection.
Comment: I'm afraid there are too many questions here, most of which do not have an absolute answer. I suggest that if you want to write short stories you should do so. Once they are written some of the other questions may be able to be answered.
Comment: As S Mitchell said, there are multiple questions here. On a Q/A site you need to ask one question at a time. But ask yourself this: In a bookstore, how many short story collections do you find, other than the occasional anthology? And if you do find a short story collection, is it by an unknown author?
Answer: I have a simillar problem with my Superhero novels I'm working.  Typically I tend to format them like a television show.  The main characters are constant and the problem of the chapter is largely introduced and resolved in the course of the "chapter".  I used this format after being a fan of the Encyclepedia Brown series, which typically had a predictable format of short mysteries (The first chapter was always solving a case for his police chief father's work load that was stumping the detectives, followed by one introducing the Lemondae-Style Detective Agency Brown ran and his nemesis Bugs Meany, a few unrelated cases (late in the series, the third chapter featured Bugs trying to get revenge (not always related to the previous chapter) by Framing Brown) and a recurring chapter about foiling the local kid conartist.).
I say largely becuase my chapters do have a bit of continuity in them that will influence the last few chapters, but I'm adicted to villains who are playing the long game.  To this regard, I think of it as an episodic television series... your setting is the same, but your stories are contained to a chapter a piece.  Can't say with publishing as I'm still on the "write it" part, but given that there are products that exist in roughly that format, I can't see a problem.
Would these formats be slice of life (Life on Venus... chapter one deals with government intrique, chapter two deals with a "typical" house wife, and so on) or is there a set plot to all the short stories?  Mostly for formatting the correct order.

How to Write a Short Story Collection?


Life of iPhone 4 LED flash?

Question: How many hours can the iPhone 4's camera flash last before it burns out? Have there been any studies done / reports published, or is it just assumed that you probably will need a new iPhone before the flash dies (with normal use)?
Comment: I think it's assumed you'll need a new iPhone before the flash burns out.
Answer: From Wikipedia:
LED Flash (Illumination)

Although they are not yet at the power levels to replace xenon flash devices in still cameras, LEDs (specifically, high current flash LEDs) have recently been used as flash sources in camera phones. LEDs are expected to approach the power levels of xenon in the near future and may replace built-in xenon flashes in still cameras. The major advantages of LEDs over xenon include low voltage operation, higher efficiency and extreme miniaturization.

So, now that we know that we have a LED (Light Emitting Diode) in there, let's see how much should that live (according the the super-experts @ wikipedia):
LED Lifetime and Failure (read all that for more info)
Short answer:

"Typical lifetimes quoted are 25,000 to 100,000 hours but heat and current settings can extend or shorten this time significantly."

Now do you think your iPhone will last 25,000 hours (worst case scenario for the LED)? That's a little bit less than three years. It's certainly possible for an iPhone to last much more than that (I still use a 1s-gen iPhone), however, I highly doubt that you're going to use it with the flash ON, for three years, non-stop. :)
Answer: I use mine as a lamp by my bed at night for 2-3 hours at a time. It doesn't even get warm and several months of doing this has not killed it yet.
Comment: Interesting. I would expect Apple to over engineer the part,  but personally would cringe at not using a less expensive night light. I don't have any reason to discount your experience so +1 from me.

Life of iPhone 4 LED flash?


CSS Language Speak: Container vs Wrapper?

Question: What's the difference between container and wrapper?  And what is meant by each?
Comment: let's assume you want to put some candies in a box. first you wrap individual candies (in wrappers) and then put all the candies (with wrappers around them) into the box (the container)
Answer: According to this answer:

In programming languages the word container is generally used for
  structures that can contain more than one element.
A wrapper instead is something that wraps around a single object
  to provide more functionalities and interfaces to it.

This definition matches with meaning of words and it's useful for HTML structures like:

...

...

...

...

...

Comment: I like this way of thinking.
Comment: This makes sense to me.
Comment: I agree with this answer.
Comment: This should be the answer and not the other one which is a non-answer
Answer: There is no difference between them.
It's just what you like to call the
 that, often, contains all content of a page
Comment: The second answer is superior to this one, in terms of disambiguation and differentiation (I'm a web dev); just my two cents.
Comment: @allesklar: Yep, that's better. Anyway, one of its functions is often to center all content
Answer: I like to throw in something here:
With current CSS standards and best practices, usually you have a container element that has the display: grid property. This div contains all the columns and rows of the layout. It also has a viewport wide background color, border and shadow. These properties are displayed using the entire width of the browser.
Now you need to add the content. You have to create another div, this a max-width: 1256px and now you give the margin: 0 auto and width: 100%.
So the structure will be:

This breaks the previous answer's logic of a container having many elements and a wrapper just one, but I've found this approach to be effective when building sections that have specific separate styling from other sections like shadows and borders.
Therefore, in some situations:
A container is for styling the entire width of a section. A wrapper is for styling and centering the max-width content inside it.
Comment: Agreed, the example above is for simplicity and to provide context to what I'm trying to explain.
Comment: In that case, I would recommend to use more meaningful class names.
Comment: These are both containers, the inner container just needs an additional class.
Answer: There can be a difference, if you choose to give'em one. Actually it makes sense to have two names for a container/wrapper, as they have different functions:
1) the standard wrap we think of has a width of let's say 960px or 60em and centers its content on the screen (margin:auto)
2) there's another wrap - the one that is in some cases necessary to implement a sticky footer. imo the sticky footer with the best browser support (no js and at least quite clean) is this one: http://ryanfait.com/sticky-footer/
apropos sticky: sticking to existing naming conventions, I like the one of apppie, which clearly distinguishes between wrap 1 (called container) and wrap 2 (called wrapper). see: http://www.apppie.org/pages/approach/naming.html
there might be other conventions. as said, that you distinguish makes sense - how is up to you.


Caps Lock LED not working

Question: I recently installed kernel 3.14.27-100 on my Fedora 19 system and now I no longer get a Caps Lock LED when using virtual terminals. (It still works on X system ). Also, it works fine running kernel 3.9.5-301. There must be a keyboard configuration somewhere that needs to be changed??  Note: the Caps Lock feature itself works fine.
Answer: Check the setleds command, see if you can turn the led light on.
In any case, it seems to me that this is bug. I would file a bug in their bugzilla, but Fedora 19 is end of life so I'm not sure if that  possible.
Answer: In my grub.cfg file their is this term - console.keymap=us in every linux boot command line. The 3.14.27-100 kernel was part of a complete upgrade with yum. I don't know if this term was always there or if it was part of a revamped grub.cfg file done with the new kernel install.
But here is what solved the problem. I just changed the term to: console.keymap=""   Also, if I took out the term completely it wouldn't change anything-problem still there. Taking it out completely must cause the kernel or some other part of the system to pick up the value - us as a default.
There is bound to be a better, more elegant way of approaching this. There are alot of values that can be assigned to console.keymap that might work.

Caps Lock LED not working


Angular Toggle values in array changes position

Question: I have an array with 4 values which I toggle (remove and Add to the array).
selectedSections: any[] = ['one', 'two', 'three', 'four'];

Then I have a button which I would click to make each selected appear and disappear.
<button (click)="toggleVal('one')">Toggle One</button>
<button (click)="toggleVal('two')">Toggle Two</button>
<button (click)="toggleVal('three')">Toggle Three</button>
<button (click)="toggleVal('four')">Toggle Four</button>

My issue is that the function below does the toggle job greatly but I need to be able to make the values appear back into the same position that they are now.
At the moment everytime a value is added it's added to the end and I need to either be able to specify what position I want it added to or a way to make them stay in position.
Here is the code below:
toggleVal(val: any) {
    if (this.selectedSections.includes(val)) {
      let index = this.selectedSections.indexOf(val);
      this.selectedSections.splice(index, 1);
    } else {
      this.selectedSections.push(val);
    }
    this.howMany();
    this.filterData();
}

How can I get it to do this?
Answer: <button (click)="toggleVal('one', 1)">Toggle One</button>
<button (click)="toggleVal('two', 2)">Toggle Two</button>
<button (click)="toggleVal('three', 3)">Toggle Three</button>
<button (click)="toggleVal('four', 4)">Toggle Four</button>

toggleVal(val: any, i: number) {
if (this.selectedSections.includes(val)) {
  let index = this.selectedSections.indexOf(val);
  this.selectedSections.slice(index, 1);
} else {
  this.selectedSections.splice(i, 0, val);
}
this.howMany();
this.filterData();
}

Answer: You can pass index value you want with your function in your html. Then you can   use:
arr.splice(index, 0, item);
It will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert).


What does a wallet do?

Question: What are the actual requirements for a bitcoin transaction?
Not the simple inputs, outputs, verification or amounts, but in the technical sense; what does your wallet do?
Everything I read says you need a client but what does it do?
People used paper wallets before, how were they able to?
Did they still need a client and if so for what reason?
Does it just connect them to the network or is there more to it?
Answer: Clients
The word client is normally used for a client-server arrangement. One example is the world wide web where web-browsers like Chrome, Firefox and edge are clients. Web-servers like  apache-webserver and IIS are servers. Clients need servers, clients and servers do entirely different jobs.
Bitcoin doesn't really use a client-server model, it uses a peer to peer model where every node is the same. At least, that was the case in the beginning. Bitcoin was originally designed to avoid the need for trusted third parties but many commercial businesses have entered the Bitcoin world and some of them use a client-server model for the software they provide. This answer will focus instead on the peer-to-peer model used originally and still used by popular wallets like Bitcoin core.
Wallets
A wallet does several jobs:

It stores data locally.

The only truly important item is the private key (or master private key)
It also caches a local copy of the transaction journal (the blockchain)
It keeps other records of transactions etc it has been involved in.

It provides a user interface for a person to spend money, see historical expenditure etc
It creates new unconfirmed transactions that spend money controlled by it's private key

It sends these to a few nearby peers to be passed on so they eventually reach miners.
Consequently it has to initially discover some peers and keep contact with them.

It keeps track of the amount of money under it's control (often called a balance)
It communicates with a few other peers to learn about new blocks of transactions

Note that the only vital task is storing a number that is kept secret. Everything  else is comparatively unimportant.
Paper wallets
a paper wallet is a number written down on a piece of paper and kept secret.
Paper wallets obviously only do the first of the jobs listed above. Storing a private key. Money can be received by a paper wallet because the recipient of a transaction is purely passive and not really involved in the processing of any transaction. The sender only needs to know an address for the recipient, beyond that the recipient is not involved.
Paper wallets were useful for long-term storage of money. However the person who created that wallet would have to have some external means of keeping track of the amount of money. This could be other paper records, use of blockchain-explorers or some other system.
To spend money, the owner of a paper wallet would have to copy the secret number into a software or hardware wallet.

Related questions:

What kinds of wallets are there?
How transaction happen in blockchain?
I sent Bitcoin to an address but the recipient hasn't yet received it
Comment: so that clears most of the question but not the core of the issue. "wallets creates new unconfirmed transactions that spend money controlled by it's private key" and "To spend money, the owner of a paper wallet would have to copy the secret number into a software or hardware wallet."  these are really what I want to know. How does this happen? What does the wallet create and what does it need for that to work in the system? what identifies a new transaction in other nodes/peers/wallets? How does another node identify an incoming message as a bitcoin transaction, rather than other net traffic?
Comment: (1) In [software](https://github.com/bitcoin/bitcoin). (2) [Packets](https://en.bitcoin.it/wiki/Protocol_documentation). (3) [Peers](https://bitcoin.stackexchange.com/q/72157/13866). (4) [TxID](https://bitcoin.stackexchange.com/questions/29878/what-is-the-transaction-id). (5) [Port number](https://en.bitcoin.it/wiki/Network).

What does a wallet do?


How to dispose of a burnt lipo battery?

Question: It caught on fire while charging.
I am not sure if it is fully "discharged" =]
Is it safe to soak it in water first?
Answer: Assuming there are still cells intact, you should try to recycle it. If all the cells have burst and burned up, then it's junk and can be tossed in the trash (perhaps seal it in an extra bag or 2 first).
Where I live, the county operates several waste transfer stations that are open to residents and which specifically accept certain types of hazardous and problematic items (paint, pesticides, old mattresses and box springs, items containing mercury (florescent lights), etc...). Check around and see if anything similar operates where you live, and find out if they will take lithium batteries; the ones in my area accept them.
Last time I made a trip I think I had almost two dozen large lithium cells: 4 multi-cell laptop batteries, several that were swapped out of iPhones, and some others that I'd accumulated over time. They took all of them for free and I didn't even have to get out of the car.
Answer: Soaking in water doesn't work particularly well, unless the water can get to the lithium. It looks like two, maybe three cells are still intact. You could drive a nail through them, attached to a piece of wood for safety, but this will also result in more fire and smoke, so be very careful and do it outside.
My preferred method is to hack my old batteries up with an old machete, and then leave them in a bucket of salty water overnight. Again this can result in fire and flame though so be very careful. I am not particularly orthodox when it comes to battery disposal.
Once all the lithium has oxidised they can be disposed of in the normal rubbish.
For future reference an undamaged, old battery can be completely discharged using one of many gadgets available on the market, then simply binned.

How to dispose of a burnt lipo battery?


How Did the Palatovelar /*ḱ/ Consonant in PIE Become a Sibilant in Satem Languages?

Question: In Indo-Iranian and Balto-Slavic languages (which are conveniently all Satem languages), there is a sibilant or affricate sound in places where Centum languages usually have a velar consonant. It seems reasonable for Centum languages to simply depalatalize, voice, lenite, or even glottalize the /ḱ/, remaining mostly in the rear/velar area, as opposed to Satem languages shifting all the way to /ʃ/ and /tʃ/. For example Quattuor in Latin is Chetiri in Slavic and Chatur in Sanskrit. How did this come about? Is there name for a rule of this sound change?
Comment: This is not limited to Satem languages in Indo-European. [Palatalisation](https://en.wikipedia.org/wiki/Palatalization_(sound_change)) has happened at least once universally in Romance (and several times more in the individual languages), it's extremely prevalent in Slavic (as @ngn mentions), Fennic languages have had several rounds of it, it's happened in Swedish and Norwegian, Mandarin is steeped in it, Ethiopic has a significant tendency towards it, etc. It's one of the most common sound changes there are.
Comment: The name for it is _palatalization_. The Slavic branch had multiple waves of that, affecting sounds in different ways. Think of a short /j/ appearing after /k/ - it makes it sound close to a soft /tʃ/. See also the letters [ќ](https://en.wikipedia.org/wiki/Kje) and [ћ](https://en.wikipedia.org/wiki/Tshe) which represent an intermediate sound.
Answer: The other answer focuses on the observation that it happens, and has a name; I address the "how" question. The starting point is having a difference between velar [k,g] and palatal [c,ɟ], the latter being a kind of fronted k,g. You can hear expert IPA demonstrations here. Although the articulatory difference between [k] and [c] is small, the acoustic effect is quite large. The palatals sound very much like linguals such as [ʃ, tʃ, ɕ]. This makes it easy to confuse true palatal sounds with postalveolars or alveolo-palatals, indeed the term "palatal" is used in many ways. As applied to IE reconstruction, the premise is that PIE started with [c, ɟ] (in IPA:  /ḱ, ǵ/ in more traditional Indo-Europeanist orthography), then the satem languages simply followed a natural phonetic tendency of alveolarization to arrive at [ʃ] etc.
Incidentally, North Saami historically also has a distinct palatal series of consonants spelled dj, which are similar to but still phonetically different from Hungarian dy, and in some dialects of North Saami, they have by this same alveolarizatin process merged with the alveopalatals [tʃ] spelled č.
The same [k] → [c] → [tʃ] path is attested in numerous languages that did not start with [c, ɟ] as PIE is assumed to have. As for terminology, the broadest term is "palatalization" which typically refers to any back of the mouth to front of the tongue shift. There are very many types of palatalization, and phonological studies there is a tendency to distinguish the alveolarization step, which is motivated by acoustics rather than articulation. The step where [ki] → [ci] is articulatory, involving an adjustment to the velar target into a fronted velar a.k.a. true palatal. Once there, the sound is susceptible to further perceptually-motivated reanalyses, based on the acoustic similarity of [c] and [tʃ].
The example of "four" actually does not relate to the Indo-European palatals, since the PIE root has [kʷ], not [ḱ]. A better example of a PIE palatal is the word "hundred", with [ç] in Sanskit, [s] in Slavic etc – the Sanskrit outcome is earlier in the historical chain than the Slavic outcome is. This just underscores the point that this shift is very common across languages, and can happen many times in the history of a language.
Comment: Did you mean [ɕ] for Sanskrit 'hundred'? At least I've never seen Sanskrit _ś_ transcribed phonetically as [ç].
Comment: I've never seen ś transcribed as ɕ. The real question IMO is what basis an author would have for making a claim about modern IPA categories applied to the phonetics of a language spoken thousands of years ago. Do you have some basis in the Pratiśakhyas for choosing [ɕ] over [ç]. What about the stops and the nasal at the same place of articulation?
Comment: Well, it's how [Wikipedia transcribes it](https://en.wikipedia.org/wiki/Sanskrit#Consonants), and also how every other description I've seen describes it (including Goldman 2002 and Cardona 2003 which Wikipedia also lists). The transcription _ś_ and the modern reflexes, such as Hindi [ʃ], also very heavily imply that it is a sibilant, which [ç] isn't.
Comment: Compare Whitney's grammar. The historical change to lingual sibilant is explained in my answer. Phonetic properties change over time: the precursor of ś was a stop, but nobody claims that ś was a stop.
Comment: Whitney uses a proprietary transcription scheme, not IPA. He does denote it _ç_ in his transcription, but still describes it as a sibilant and a "_sh_-sound". I don't know offhand what contemporary grammarians say about the production of this particular sound, but is there _any_ evidence that palatalisation had not yet led to an actual sibilant by the time of Classical (or even Vedic) Sanskrit?
Comment: I decided to check Wikipedia's claim compared to Cardona or Goldman's words, and I don't see evidence in those sources to support the claim for  [ɕ], the authors use IAST not IPA. The philological question deserves a separate question.
Answer: As ngn says in a comment, this is palatalization.
It is a very common sound change. It happened in the descendents of the poster-boy centum language Latin:
Latin ''centum'' (/k/) -> Italian ''cento'' (/tʃ/), French ''cent'' (/s/), Spanish ''cien'' (/s/ in Latin America, /θ/ in Spain)
In Germanic it happened differently in different times and places: Danish ''kirke'' and Scots ''kirk'' have neither /k/ palatalized, German ''Kirche'' has only the second palatalized, Swedish ''kyrke'' has only the first palatalized, and English ''church'' has both.
Further afield, Arabic has no /g/ because where its relatives have that sound Arabic has /d͡ʒ/, for example Arabic جَمَل (jamal) vs Hebrew  גמל (gamál) "camel".
And Beijing used to be written Peking because when Europeans first encountered the city the Chinese name had a /k/ in it, but over the last four hundred years the sound has been palatalized to /tɕ/.
Comment: German never actually had palatalisation of /k/, but it did have the [High German consonant shift](https://en.wikipedia.org/wiki/High_German_consonant_shift) which turned /ˈkirikaː/ into /ˈkxirixa/. The initial /kx/ was later undone back to /k/ in most of the German-speaking area, and syncope + vowel reduction turned /kirixa/ into /kirxə/, the current underlying form. And there _is_ productive palatalisation for /x/ → [ç]. Also note that the Swedish word for 'church' still has the original final _-a_ (_kyrka_, not _kyrke_), so it doesn't have the context for palatalisation of the second k.
Comment: Unlike the Swedish form, in Norwegian (where _-a_ has often been reduced to _-e_ or _-ə_), there are dialects, especially in more Nynorsk-adjacent areas, that have palatalised both k's and now have [_kyrkje_](https://en.wiktionary.org/wiki/kyrkje) and similar forms.


How to indent existing OCaml code

Question: I have ~30.000 lines of badly indented OCaml code (including mly and mll files) and would like to indent them. I tried googling for variations of 'ocaml indent' the closest I can get is to use Omlet.vim and indent the code one line at a time (via C-f in insert mode). Is there a way to do the indentation for all the 30000 lines?
Answer: I use Emacs as my editor with this package installed:
http://caml.inria.fr/pub/docs/u3-ocaml/emacs/index.html
To indent existing code you need to highlight it and then use the key combination C-M-\
You can script this per file pretty easily and I find the indentation to be pretty good.
Comment: You can do the same thing in tuareg-mode with `M-q`. Don't know how it scales to thousands of lines though.
Comment: @Chris, you're correct.  I did use tuareg when I started learning OCaml and I do think it's more popular than the package hosted on the inria site.  I just happen to prefer the package I posted.  But take that with a grain of salt as I'm not the most polished OCaml programmer around;)
Answer: When I want to re-indent a whole file in vim, I use the following key sequence:
g g V G =
Breaking this down for you, g g moves the cursor to the beginning of the file.  V enters visual mode.  G selects to the end of the file.  = indents the selected lines.
This should be much faster than your method of applying indentation line by line, but yet will use the same rules (warning: using Omlet, indenting a whole file may take a while).
Answer: Now, one can use ocp-indent (opam install ocp-indent) and invoke it like this :
ocp-indent bad-indented-ocaml.ml > well-indented-file.ml

Answer: Use ocp-indent tool for this. Here is an example Makefile rule, that will automatically indent you ml files.
.PHONY: auto-ocp-indent
auto-ocp-indent: *.ml
    for mlfile in $^; do ocp-indent -i $$mlfile; done

How to indent existing OCaml code


which aws instance types need subnet id specified?

Question: Cloud formation says:

The specified instance type can only be used in a VPC. A subnet ID or
  network interface ID is required to carry out the request. Launching
  EC2 instance failed.

Which instance types do not need a subnet ID or network interface ID?
Comment: You should *always* use a VPC.
Answer:
Which instance types do not need a subnet ID or network interface ID?

There is no instance type that does not require those things. EC2 Instance is a Virtual Cloud Compute so you need them to define where the instance will be deployed on and how network can connect to that instance.
If you use AWS console wizard, it sopports you to run quickly so you don't need to specify those information, wizard will create them for you.
But if you use CloudFormation, you must define manually.
Answer: So if you have an older AWS account, you may still have access to EC2 "Classic", which means it is possible to launch an instance without needing a VPC.  Only accounts created before Dec. 2013 support EC2 Classic.
However, not every instance type supports being launched into EC2 Classic - in fact, most of the newer instance types can only be launched into a VPC.
The full list is here, but the M/C/R4 families plus T2s, are VPC only.
Answer: I assume your question is "Which instance types can be launched without a VPC"?
Very old AWS accounts were NOT automatically creating a default VPC and there might be some instance types (I don't know which instance types) could be launched without a VPC.
Currently all AWS account will create a default VPC and you can create all instances ONLY inside a VPC.


How to replicate a Laowa 24mm Probe lens in Blender cameras?

Question: I've replicated plenty of lenses, MM, f/stop, etc. Its all pretty straight forward but this one has me baffled. I've adjusted the camera scale but that doesn't work either. Anyone ever tried to mimic this lens?  If so your advice would be greatly appreciated.
Answer: Camera settings don't scale in Blender. If you scale the camera object in the 3d Viewport, all you're doing is changing how big it displays and not the lens or any of the settings int he camera properties.
What you're trying to achieve is a perspective trick. If you shoot anything in real life from a low angle and with a wide enough lens, the subject tends to feel bigger and more imposing.
So to take this into blender, you can do it a couple of ways. Set up a wider lens or scale up your models. The latter I wouldn't recommend. it messes with the realism too much because of lighting and textures etc.
So shoot low, and wide.
Comment: Lockey, I went back and figured out I actually increased the size of the object to give the illusion you're talking about. (Its been a long week) Regardless, it still never looks quite right. Is a 24mm Laowa probe actually a true 24mm?
Answer: What matters is the  field of view. Set it to 84.1 degrees and get the camera close to the objects


Are members of the Night's Watch allowed to join the Kingsguard?

Question: Very much related to this question Can a Kingsguard member be sent to the Night's Watch? but now the other way around, do we know of any Night's Watch brother that became Kingsguard?
Comment: Thing is, knights had to leave the Kingsguard to join the NW. it would be much harder to to the other way around, as you can't leave the NW
Comment: @Kepotx it's pretty difficult to leave the Kingsguard though
Answer: Almost certainly not and I can find no cases of it ever happening
There are no recorded cases that I can find of a Night's Watch brother being released from their oaths and joining the Kingsguard. In fact I can't really think of a case of a sworn brother being released from their oath. We have Jon Snow but he pulled the whole loophole trick in the show and we're yet to see what happens in the books so we can discount that. However, Stannis does offer to legitimise him and free him from the oath, though it is not clear if he actually can do that or is doing it because he has the army and power to enforce it.

"As you wish. But consider quickly. I am not a patient man, as your black brothers are about to discover." Stannis put a thin, fleshless hand on Jon's shoulder. "Say nothing of what we've discussed here today. To anyone. But when you return, you need only bend your knee, lay your sword at my feet, and pledge yourself to my service, and you shall rise again as Jon Stark, the Lord of Winterfell."
A Storm of Swords, Jon XI

The only known case of someone else being released from the oath is Samwell Tarly at the end of Season 8 but it happens off screen. We can assume the new King released him so it would appear that kings can do this but usually don't as the men of the Watch are usually less than stellar. Sam is also made Archmaester so this might have something to do with it as well.
The oath explicitly states "I shall live and die at my post." and so would make it clear that one cannot simply leave, as we see deserters are executed.

Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come.

In fact the Kingsguard oath was modelled on the Night's Watch one and so it would appear whilst they have common elements they probably conflict as Kingsguard members serve for life.

It was Visenya, not Aegon, who decided the nature of the Kingsguard. Seven champions for the Lord of the Seven Kingdoms, who would all be knights. She modeled their vows upon those of the Night's Watch, so that they would forfeit all things save their duty to the king.
The World of Ice and Fire, The Targaryen Kings: Aegon I

Lastly, it is worth noting of those Kingsguard that were sent to the Night's Watch most had lost their king and broke the oath by betraying said king. And the odd one out broke the oath by fathering children. Breaking the Night's Watch oath results in death not being released from it to join a more prestigious organisation.
Comment: Is there some proof that Sam was released from his NW oaths?
Comment: @svenvo7 Only visual clues in that he's no longer wearing the black at the Small Council scene but was at the Great Council. And he's now the Archmaester and I doubt someone could be both.
Comment: It seems there is enough leeway in the NW oath to allow for his service in King's Landing. After all, his post is whatever the Lord Commander decides. The clothing is some indication but that's what he wore in Old Town while still a NW member.
Comment: @svenvo7 The most likely implication is that Sam was released from his vows, after all he can't serve the Night's Watch if he's Archmaester and serving the realm. However, feel free to interpret it how you want.
Comment: Based on the accepted answer of https://scifi.meta.stackexchange.com/questions/4724/flagging-answers-that-dont-present-textual-evidence it appears I may be too harsh in my desire for definitive proof. +1
Comment: There is also a moment in ASOS where Robb discusses legitimizing Jon Snow, absolving him from the swatch, and naming him his heir in the case that his wife is unable to provide a son.
Comment: Can't we just agree that season 8 is not concidered canon? Sam released from his oath and becoming Archmaester shortly after serious misconduct at the Citatel let alone the lack of any noteworthy achievements at the Citadel ... `arbitrary` doesn't even begin to describe this.
Comment: Perhaps King Brandon the Broken revised the scope of the Night's Watch, meaning that protecting the realms of men isn't necessarily something that needs to be done at the (now broken) wall. Perhaps the interpretation is that Sam, as Archmaester AND Night's Watch member, protects the realms of men in King's Landing as Archmaester.
Comment: *eyeroll* There was no Night's Watch any more after the victory against the White Walkers. And I think a serious reform of the Citadel was long overdue.


Direction of the force of a mechanical wave

Question: Currently, I am learning about mechanical waves in school, including sound and what-not. My teacher provided us with this formula for the energy per length of any given wave on a string:
$
E/L = 2(π^2)(f^2)(A^2)μ
$
where $E/L$ is the kinetic energy per unit length, $f$ is frequency, $A$ is amplitude, and $μ$ is the linear density of the string. Being a basic introductory physics class, the teacher didn't get into the derivation of this formula, but more so just threw it at us. However, I noticed that $E/L$ has the same units as force $(kg \cdot m/s^2)$ so I was wondering if kinetic energy per unit length is another way of representing the force of a wave. Which way would this wave force point? Is it of any significance?
Comment: Are you sure about the term "power" because power is not energy per unit length, which you correctly point out has units of force. Power has units of energy per unit time or force times velocity.
Comment: Whoops, yeah that's a mistake, thanks for pointing it out.
Answer: It is indeed a force, the tension in a taut string. Tension takes units of energy per unit length for a string. An analogous situation is surface tension of the surface of a liquid, which has units of energy per unit area. Both are properties that affect wave propagation on the string, or the surface of a liquid respectively. For example, wave velocity would depend on the elastic properties of the medium, which in this case is the tension. At each point, it tries to minimize the length of the string, or the area of the surface. You could think of it as springs holding a lattice of balls together to get a sense of the direction of the force.


Does distribution of FPO by a company affect the current market price of the company in secondary market?

Question: If a company announce and distribute the "Further public offer" (FPO) will the market price of that company in secondary market get adjusted? If it adjust then what will be the formula to find out the adjusted market price after the FPO distribution?
Comment: @SOuřaanGřg The point being made is that _the company_ doesn't adjust the price (it doesn't say "_The new price of our shares is..._"). In both cases, _the market_ may "adjust" the price in anticipation of, or following, events that the company performs. Even here, there is no "explicit adjustment" (i.e. "calculation" of the new value)... traders will buy/sell shares and adjust bid/ask prices based what they feel the company is (or is about to be) worth and the overall price will vary accordingly.
Comment: Companies do not control the market price of their shares.
Comment: When dividend,right are distributed by the company to concern share holders after the book close date ending the current price of such company get adjusted in secondary market isn't it? It mean the FPO doesn't adjust the current market price of a company in secondary market? @BrenBarn
Comment: @TripeHound that would make a very good answer so... please don't answer in comments!
Comment: @MD-Tech. Answered. I thought of it more as a clarification than a full-blown answer, but am happy to turn it into an answer.
Answer: In light of the recent edit to the question ("Does distribution of an FPO affect the current market price..."):
It may depend on what type of FPO is being made. Both this Wikipedia page and this Investopedia page discuss the two types in detail; the two types are:

Dilutive FPO: New shares are issued and sold by the company. The company directly benefits from new investment income. However, since there are now more shares in existence, existing shareholders may feel aggrieved since they will own a smaller proportion of the whole company. Whether the FPO affects the share price depends on a number of factors:

If the new shares are sold at the current market price, and not so quickly that they depress the market through normal supply-and-demand effects, then –
other things being equal – the price probably shouldn't change (while there are more shares in circulation, the total value of the company will have increased by "the going rate" of those shares, so the overall value-per-share should remain the same).
If the shares are offered at the market price but too quickly, then the normal laws of supply-and-demand may (at least temporarily) reduce the share price. However, if all the new shares were sold at (or near) the original market price, then this may recover if the value-per-share remains (roughly) the same. If a significant number are sold at a reduced price, the value-per-share will have reduced (see below) and the share price may remain depressed.
If the new shares are offered below the current market price, then you can expect the share price to drop, as the increase in the value of the company will be (proportionately) less than the increase in the total number of shares.
All the above assumes no change in the perceived "strength" of the company. Obviously if investors see the FPO as "the last-ditch effort of a struggling company", the price will decline (as people sell); if they see it as a "sound act of a growing company", then the price may rise as people are drawn to it.

Non-dilutive FPO: Here existing privately-held shares (typically owned by a directory or venture capital partner) are sold. Because these are existing shares, the total number of outstanding shares does not change, and so there is no dilution. However, the proceeds of the sale do not benefit the company itself.
As with a Dilutive FPO, selling the shares too quickly, or below current market price would be expected to lower the price. Another factor that could affect the share price is whether the "sale by directors" is seen as "rats leaving a sinking ship" or "justifiable realisation of the strength of a health company".

The original question asked (or was phrased as if it were asking) whether the a company alters the share price because of an FPO. The original answer explained that it didn't (but that market forces – as discussed above – may cause the price to change.