How long should I wait before sending a thank you email?

Question: Should I send a thank you email immediately, or perhaps wait a day or more? Does it make a difference if its a phone interview or an in person interview? If you wait too long, then it is likely to have no effect, or even seem out of place. However, if you send it right away, it  takes away one of the advantages, which is that it reminds them of your strengths.
Comment: Here's a link to [a related question](http://workplace.stackexchange.com/questions/1446/send-thank-you-email-after-phone-interview); the community can decide via flags and votes if there is enough of an overlap to call this a duplication since the intent (being courteous) is pretty similar.
Comment: @jcmeloni: That question don't seem to overlap. That is about whether you should send a thank you email, this is about whether you should wait
Comment: Since I'm not a fan of 1-line answers to gain rep, I'll give you an answer in this comment :) ... wait as long as or as short as you need to prepare a pleasant and honest note, and no it does not matter the type of interview.
Comment: Sure...but it's implied (at least to me, and perhaps I'm odd, which is why I said "the community") that since the answer to that one is clearly "yes, send one", it should be sent reasonably soon after an interview to achieve all the positive results that are delineated in the answers there.
Answer: It is a good thing when you have an excuse to contact them by phone or email. Sometimes they need a list of references, or an electronic copy of the resume.
While you are sending the email turn it into a thank you email. You should send it within 24 hours. I try for close of business for a morning interview, and by early the next business day for an afternoon interview.
Comment: +1, I would also add. Don't forget to ask for a business card in case you have any more questions. Its a way to get their contact information without asking for it (if you don't already have it)
Comment: +1 for within 24 hours I would wait at least 2 hours after the interview to show effort not just send it immediately when you get home/off the phone.
Answer: Emails should generally be sent within a day or two.  Exception being if your interview was on a friday, try to send one by EOD, or an hour or two after opening on monday.  Lots of times, over the weekend, people get flooded with emails, and won't always want to read them all if they're not urgent.  Waiting until the recipient(s) have settled down, gotten through their morning routine, and will notice a new email appear is somewhat courteous.  If you're sending a paper letter as thank-you, put it in the mail the next day.  Make sure you date it in formal style, so they'll tell when you sent it.
Answer: I would wait about 1/2 a day.  It's a good idea to draft it immediately after the interview while ideas are fresh, but it's also a good idea to then put it aside for a few hours, maybe sleep on it, and then review it for both content and tone and send it.
I would have a minimum of 4 hours to not be (or seem) rushed and a maximum of 3 days while you are still current in folks minds and they are still deciding- which can vary (a lot) by industry and technology from minutes to months (e.g. startup to government) so adjust accordingly.
Answer: If the decision is being made right away, such as even the very next day, it is imperative that the thank you note arrives right away. This is often the case with teacher interviews. Send them the same day as your interview for snail mail, so hopefully they will arrive the next day before the decision is made. Send on the same day for email responses too, waiting several hours. Even if the decision is already made, a nicely written thank you note will keep you in the running for the next posting.


Electric motor: rear, center or front?

Question: I'm looking for an electric bike. I see motors available on rear, center, and more cheaper, a wheel with a motor to adapt to front. Any experience to help me to make a decision?
Comment: The beauty of hub motors is their simplicity.
Comment: If this really hasn't been asked before, I think it would be a good question if you fixed spelling, formulated a proper title etc.
Comment: This is very close to a duplicate of [Center motor ebike costs more, is it worth it?](https://bicycles.stackexchange.com/q/44804/7309) but that question doesn't discuss front hub motors
Comment: Understand that the different configurations are associated with different modes of operation.  Some setups are better suited for just "helping" the rider pedal, others for carrying the entire load.
Answer: I had a front hub motor in a retrofit kit.
PRO: Its really easy to fit, just leaves a lot of wires hanging on the frame.
CON: Any motor adds weight, and if your bike has suspension it could be unsuspended weight which is not ideal.
CON: The front wheel carries less weight than the rear, so it can slip easier.  Powering through a corner is a bad idea, and I even got wheel slip by taking off from the lights with power on and pedalling hard.
My motor was a hard on/off switch, with no sensors or throttle, and was rated at 250W.  So you could press the button and just glide with no pedalling.

My general knowledge of pedal assist bikes is that you have to be pedalling to get assistance.  This can produce some interesting effects at low speed, when turning under power, and when pushing hard to take off.
A rear hub motor will have the most oomph for the same wattage, but it will add even more weight to the rear of the bike.  This can contribute to rear punctures and rear wheel slips when cornering.
A center motor/BB motor distributes the weight evenly between wheels, and keeps the weight low down.  However they generally need a special and custom frame.
Don't ignore batteries either - they're always too small in capacity and too big in weight.  I had Sealed Lead Acid batteries, and lithium would have been much nicer.
Comment: I suspect that the weight of the batteries swamps the weight of the motor in most cases.
Comment: Of course, putting the weight aft is good for traction and control.  And high weight is not that much of a problem if it doesn't jiggle around.  (After all, the biggest weigh on the bike by far is higher still.)
Comment: @DanielRHicks in my setup absolutely - motor was ~5 kilos, and 7AH SLA batteries were ~3 kilos each, for a total of 9.  Add another couple kilos for wiring and controller and battery framing.      By comparison a modern Bosch lithium battery is quoted at 2.5 kilos, and 2-3 kilos for the motor (although its not clear how much else is not included in those weights)
Comment: @DanielRHicks another related thought - some kits put the batteries on or in a rear carrier rack which is high as well as being quite a long way aft.

Electric motor: rear, center or front?


What will happen with 2 AV signals

Question: Should be a quick one.
I know you can mix AV channels to overlay images but if I connect 2 raspberry pi to one screen in AV and no multiplexer how will the channels mix if they are at different resolutions? This is not taking into account any input lag from the Pi of course.
Answer: You can't combine 2 composite video outputs - you would just get a corrupted output. You would need some form of switcher to switch one or the other.
Comment: OK then I'll definitely need a multiplexer if I was to view both at the same time. Is there a way to do this via software?
Comment: You could use vnc/ssh on one Pi to view the screen on the other Pi assuming on a network.

What will happen with 2 AV signals


How cold can it be when painting exterior?

Question: Last fall we rebuilt our front porch steps.  Now we are finally getting warmer weather and I want to paint these as soon as I can.  The primer I have does not give a minimum temp rating.  I figured if it is in the 50s I would probably be OK.
Comment: I'd double check with the paint manufacturer. 10 Celsius is probably on the borderline.
Answer: Primer dries fast, so 50's will probally be OK, especially if it gets some direct sunshine. Give it some time however, before painting. I have used exterior paints as low as the 40's as long as night time temps are not going much lower, or paint/primer at least 4 hours before temps drop a bit. Some paints do give a temperature range.  There are low temperature paints that will cure down to upper 30's with no problem.  The main problem with priming or painting in cooler temps, is that you must let it cure enough before applying the next coat. That may take a couple of moderate temp days as it will not cure in the colder nights, dew or excessive moisture, as that will delay the curing process or discolor the finish.


Access is denied while processing web.config with Sql Server Compact

Question: I just deployed an ASP.NET MVC3 site to a new hoster. It is using the Plesk Control panel. The site is using Sql Server Compact 4.0 and EricEJ's Sql Server Compact Membership and Role provider.
When trying to access the site, I'm getting an access is denied error on the web.config file where I add the SqlCeMembershipProvider:

Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.
Parser Error Message: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
Source Error:
Line 31:         <clear />
Line 32:         <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="ApplicationServices" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/" />
Line 33:         <add name="SqlCeMembershipProvider" type="ErikEJ.SqlCeMembershipProvider, ErikEJ.SqlCeMembership" connectionStringName="SqlCeServices" applicationName="/" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="true" passwordFormat="Hashed" writeExceptionsToEventLog="false" />
Line 34:       </providers>
Line 35:     </membership>

The SqlCeServices connection string is configured like this:
<connectionStrings>
    <add name="SqlCeServices" connectionString="data source=|DataDirectory|\SqlCeAspnetdb.sdf" />
</connectionStrings>

When I go to the "File Manager" in the Plesk control panel, and click on "change permissions" for the "App_Data" folder, all the users (that I can configure) have write and modify permissions:

Although, when I click the "advanced" button, this is what I see:

The entry on the bottom for "Plesk IIS WP User (IWPD_321)" has all the permissions. But apparently, there are 2 additional entries for that same user on top. These don't have write permissions, but anything I change for those 2 doesn't get saved. When I come back to the screen, they are again as shown (without write permission).
I'm not sure what I can do, or what I have to ask the helpdesk of the hoster to get this solved (they don't seem to have experience with Sql Server Compact).
I tried removing the lines from web.config where the SqlServerCe Connection string is used, and then I can run the site, but I can't create (register) users or roles, as I don't have a Sql Server database.
Any suggestions on what to try next?
Answer: I found the solution. I needed to add "Read/Execute" rights to the \bin folder and all its child objects for the "Plesk IIS WP User (IWPD_321)" user.
The \bin folder is where the Sql Server Compact binaries reside.
Guess I was focusing on the \App_Data folder too much...
Comment: Thanks!!!! after 100 (ok, 12) tries this is the one that works!


Let a friend/child try a game on iOS?

Question: Is there currently (iOS 12) any way to let a friend or child try a game on an iOS device, starting from the tutorial, without losing my own progress?
Answer: In general, no. The game developer can store progress on the device locally, on an iCloud / Game Center log in basis (or both) or save data off on a private server / public cloud.
It really depends very specifically on how the game was programmed to behave and you'd need to contact each vendor / read their documentation or experiment to understand how or if game progress and data persist on iOS.
Even deleting an app won't remove some game data and some people love that and others, not so much.

Can I delete an iOS game and retain my progress?
Answer: Settings → Game Centre has options to Sign out, set up different Apple ID for Game Centre or use a different profile.
Comment: That would rather depend on whether or not the game depends on the Game Centre. if the progress is saved externally, at the game dev's own site, the it may not be possible.
Comment: @ankiiiiiii There is all manner of troubling behavior that ships. Some games even store parts of data in Game Center, part in iCloud, part on the device so it's really a mixed bag of every flavor beans - https://harrypotter.fandom.com/wiki/Bertie_Bott%27s_Every_Flavour_Beans
Comment: @Tetsujin But that remotely stored progress would be exclusive to ID. Mapping it to the device is troubling .
Comment: @ankiiiiiii I suppose this doesn't allow easily switching between multiple IDs?

Let a friend/child try a game on iOS?


In Windows Explorer (set to detailed format), can I change the color of some file names?

Question: Several months ago, I accidently changed the color of some file names to blue in Windows Explorer. Now, I'd like to do that with a purpose. But I can't figure out how to.
Answer: Blue file names indicate you've compressed the files via the NTFS filesystem. To compress or decompress files, go into their property sheet, and under the Advanced attributes button is the option to compress or not.  You can also choose to encrypt files, which would display their file names in green text.
The tool Folder Marker can allow you to change the color of folder icons without compressing or encrypting them, but it does not change files nor does it change the text color.


InDesign: how to apply styles to specific words/phrases

Question: Is it possible to change the font style of specific phrases within an .indd document? I have several phrases to update in a giantic wall of text and all I need to do is change the font to a cursive. Be mindful that some parts of text have different font sizes and other styles.
Answer: An automated way is to use GREP Styles via the Paragraph Style options. This feature is automatic so every time the phrase appears it will instantly apply the formatting without any manual search needed. A Character Style will need to be defined and then this will apply as a rule within your Paragraph Style.
If you're using multiple styles, you need to do this for each one.
Answer: Ok I found out how to do that:

Press Cmd/Ctrl-F and type in the phrase you wish to change.
Then select "more options" to show the format changing options and select w/e formatting you need for that specific phrase.


How to use digital pin as ground?

Question: I have recently brought an arduino nano. It has only two ground pins but I needed three for my project. Is there a way to use a digital or analog pin as ground pin? Please show me how to do it
Comment: ground is only one. connect every ground wire to one ground pin
Comment: Careful with using GPIOs as GND sinks.. An I/O pin can sink only so much current. For a GPIO bank, 100mA max, one pin recommended 20mA (https://playground.arduino.cc/Main/ArduinoPinCurrentLimitations). I would connect directly to the main GND (from the power supply). Solder a few more wires if you have to.
Answer: If your project is on a breadboard, you can use one of the "rails", typically the blue longways row at either edge of the breadboard, to collect all of the necessary grounds, and wire that to one Ground pin on the Arduino.
If you're building a printed circuit board to connect to the Arduino, do the same thing - collect all of the PCB grounds together and wire that to one Arduino Ground pin.
If you're using a manufactured shield, you may have to get creative about collecting your grounds. A tiny breadboard is one way. Another is to solder a number of wires together in star-formation, insulate the solder joint with tape or shrink-tube, and connect one of the star's points to the Arduino ground.
If some of your devices needing grounds are low-current devices such as LEDs, you could set an unused pin to OUTPUT mode, and LOW, and use it as a ground, but the device must not be passing more current than an Arduino pin driver can sink. From Atmel's data sheet for the AtMega328p (used in the Uno):

Although each I/O port can sink more than the test conditions (20mA at
      VCC = 5V, 10mA at VCC = 3V) under steady state conditions
      (non-transient), the following must be observed:
ATmega48A/PA/88A/PA/168A/PA/328/P: 1] The sum of all IOL, for ports C0 - C5, ADC7, ADC6 should not exceed 100mA.
2]     The sum of all IOL, for ports B0 - B5, D5 - D7, XTAL1, XTAL2 should not exceed 100mA.
3]     The sum of all IOL, for ports D0 - D4, RESET should not exceed 100mA.
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test condition.
Answer: There is no need to separate grounds, you can connect all grounds together. In fact they are connected together on the board itself.
Answer: You can just try converting two digital pins as 5V VCC and ground.
This will be useful when we use multiple sensors.
<code>#define VCC2  5 // define pin 5 or any other digial pin here as VCC2
#define GND2  2 // define pin 2 or any other digital pin as Ground 2

void setup() {
  pinMode(VCC2,OUTPUT);//define a digital pin as output
  digitalWrite(VCC2, HIGH);// set the above pin as HIGH so it acts as 5V

  pinMode(GND2,OUTPUT);//define a digital pin as output
  digitalWrite(GND2, LOW);// set the above pin as LOW so it acts as Ground
}

void loop() {
}
</code>
Comment: I'm not sure I'd recommend this, but if you're going to do it you should know that it will have very limited current available, which will depend heavily on the Arduino involved, or rather its MCU.  You might allowed up to 40mA, but also perhaps only 4mA. And that your new "VCC" will drift toward ground as you draw more current.  Likewise with "GND" raising toward VCC.  They may not start as near the board VCC and GND as you like, as they're not intended for this purpose but only to produce logic levels.
Comment: It can be useful if you need to turn on/off the sensor during operation, but as timemage said, it is not advised. Using a transistor controlled by the Arduino's pin is way better.

How to use digital pin as ground?


ICD-10 codes in Machine Learning

Question: Can anyone provide specific techniques with using ICD-10 codes in Machine Learning? I have usually used a simply approach of creating multiple binary column representing ICD-10 codes… which can get extremely long. Or I have used Hashing features. Are there other techniques or ways to use ICD-10 codes in ML? Anyone can provide a useful link to see various approaching to modeling such features?
Answer: Most machine learning around ICD codes deals with auto-encoding documents or NLP to extract ICD codes automatically from documents. Once you have them, most applications I have seen use them as is.
One simple alternative would be to assign the codes to relevant categories to reduce the number of levels and make them more interpretable. For example

injury types (e.g. F00–F99 for mental disorders)
body parts (e.g. S10-S19 & .. for neck injuries)
severity of injury etc.

depending on your application. Of course, if you don't want to define the categories beforehand, this can be done using some clustering or embedding method etc.
Comment: Is there a public project serving as a baseline? If so do you mind sharing a link?
Comment: Additional methods might be topic modeling of the code descriptions as a form of clustering, comparing code titles or description to an medical text embedding as opposed to creating an embedding from them, or tying medical codes to other health information like labs and prescriptions.  There is an [API](https://api.diagnoss.com/docs/) to get ICD10 codes from text now.
Answer: I've used ICD-10 codes using one-hot encoding / dummy variables as you describe in your Q. This creates a very sparse binary design matrix which has a large number of features as you say. Some ways I've used to make it more manageable RAM-wise:
(Out of interest how long are your unique code columns, and number of row samples?)

I find that by using parent codes (e.g. omitting the "." after the ICD codes: "G12.21" changes to "G12") there are fewer columns.
As the design matrix is binary and very sparse, unless you are interested in the rare diagnoses, you can omit many co-morbidities depending on how rare the diagnoses are. e.g. discarding a few rare diagnosis for each patient (in my case with 200k rows, reduced columns from ~7,500 to ~6,500)
Answer: I was going to try this for codes of the form A12.3;
Take the first letter, as a position in the alphabet, add 10 and then multiply by 10, giving you 26 values between 100 and 360
Append the second two digits to this number, i.e add 12 from the example above, to give 10012.
Then append the final digit, i.e. 100123.
This should give you numerically comparable distances that you'd get from analysing the ICD10 codes as a tree, i.e. all codes that are near each other on one branch are numerically near each other on another branch, and shouldn't spill over too much. By that I mean that the numbers at the high end of one letter code shouldn't be nearer the lower numbers of another letter code than they are to other members of the group.
If anyone has any comments, I'd be interested?

ICD-10 codes in Machine Learning


Why can Sephardic Jews Eat Rice on Passover?

Question: Why can Sephardic Jews eat rice on Passover?  Is this specified in the Torah somewhere?
Comment: You are looking at the situation in a very backwards manner. Sepharadim are keeping Halacha on this one, it's the Ashkenazim who added to it later. In tge time of the gemara all the big rabannim would eat rice, such as rava
Comment: @BaalShemotTovot I wasn't aware that there is a Halacha that you must eat rice on Pesach, such that Ashkenazim are violating it.
Answer: This question ought to be, "Why can Ashkenazi Jews not eat rice on Passover?"
There are 5 grains that make Ḥametz when mixed with water and allowed to rise: barley, rye, oats, wheat, and spelt. Any others that have been added by communal custom are just that - additions by virtue of communal custom.
Answer: Kitniyot are not specified in the Torah at all.  They are chumrot — binding customs of the community.
The Sefardic kitniyot custom permits rice provided it has been carefully checked grain-by-grain before Passover begins to ensure that no chametz grains are in it.  (How carefully depends on the tradition; I have seen "3 times" and "7 times" specified by different traditions.)  Ashkenazic custom is much more restrictive when it comes to kitniyot.
Comment: I appreciate your answer, but I have no idea what those terms mean.
Answer: Chametz is a biblical term which refers to grains which ferment when water is added.  This fermentation causes the dough mixture to puff up.  The talmud (Pesachimn 35a) discusses the fact that rice and millet also puff up when water is added.
The structure of the discussion:
The Mishna lists the grains that one may use for the mitva of eating matza on the first night of pesach:  Wheat, barley, spelt, rye, and oats.
The gemara brings tannaic sources that the list is derived from a biblical juxtaposition of chametz and matza- only grains which "ferment" (become chametz) may be used for matza, but not those which "rot".
The gemara continues to underscore that the above mishna rejects the opinion of the tanna Rabbi Yochanan ben Nuri, who classifies rice and millet as grains which ferment.
From the above gemara, there seems to be a tannaic dispute as to what state of fermentation is called "chametz".  Rabbi Yochanan ben Nuri has a broader definition of the term chametz, but his minority opinion is rejected from halacha in favor of a more specific type of fermentation which would categorize rice as non-chametz.
Communities which refrain from eating rice on Pesach are limited to those communities who have accepted to do so.
Comment: Just to clarify: do those who accepted this chimes hold like r yochanan ben buri?
Comment: @Vram It seems not, as Ashkenazim can own kitniyot on pesach.
Comment: @Vram, like DoubleAA alluded to, rabbi yochanan ben nuri is universally rejected (with rice just being kitniyos).  I brought in the gemara because kirby seemed to be unclear about the source for limiting the  grains that are categorized as potential chametz.


How do I query my Wordpress posts on another HTML page using the Wordpress Restful API?

Question: I have a fully functional Wordpress site and I want the to create a new separate website that displays the posts from the wordpress site using the Wordpress Rest API.
I understand that typing http://my-website/wp-json/wp/v2/posts into a browser shows me this information but I want to code it into the new separate site. I don't even know where to start! Does  anyone know how to help?
Comment: This is like saying " I heard about that PHP thing, and I want to use it, where should I start? :( You start by having a concrete usage case which you detail in your question, and then maybe people will be able to advice you ;)
Answer: You'll want to use cURL to do server to server connections. There are plenty of examples online but here is a good starting point so you can at least know what functions to look into.
http://php.net/manual/en/curl.examples-basic.php
Comment: Please provide a CURL example then on how to do this.
Answer: You could use a function like the following and call it like my_prefix_fetch_data( 'posts?per_page=3' ) or my_prefix_fetch_data( 'categories' ).
if ( ! function_exists( 'my_prefix_fetch_data' ) ) {
    function my_prefix_fetch_data( $query ) {
        $response = wp_remote_get( esc_url_raw( 'http://my-website/wp-json/wp/v2/' . $query ) );

        if ( is_wp_error( $response ) ) {
            return array();
        }

        $output = wp_remote_retrieve_body( $response );
        $output = json_decode( $output );

        if ( empty( $output ) ) {
            return array();
        }

        return $output;
    }
}


Putting meat spoon in dairy coffee

Question: What are the primary sources that discuss the rule of taking a meat spoon and using it in my dairy coffee. Would it matter how long ago the spoon was used?
Comment: Suppose I mixed hot dairy food in the morning and then realized that the spoon I had used had been used to mix hot meaty food the night before. Can I eat the dairy food? Is the spoon treif (non-kosher)? Does it matter how long prior the spoon had been used?
Comment: I am not asking for a psak. I am looking for the primary sources that discuss the rule in this case.
Comment: This is reopenable now but is it what you mean to ask? The original question was what to do once you've reused the spoon; this asks whether you can do so. Here (next comment) is how I reworded your question (but my edit was rejected because you'd reworded it yourself meanwhile). See what you think.
Comment: What are primary sources? Shulchan Aruch? Talmud? Mishna? Chumash? Not sure why Google can't answer this - and what you're trying to ask.
Comment: @msh210 I think, given the answer, you should feel free to employ http://meta.judaism.stackexchange.com/q/1299/759
Answer: Assuming the coffee wasn't heated in that mug, then it has the status of Kli Sheni, which the Shulchan Arukh rules (105:2) does not transfer flavor bedieved (though lechatchila it should be avoided). However, see the gloss there of Rabbi Akiva Eiger who posits that since metal utensils can be Kashered, it is not considered a bedieved situation since you can just Kasher them. Ceramic utensils however (such as, likely, the mug) would be fine since there is no further recourse. Accordingly, one should not put the meat spoon in dairy coffee, but if one did then coffee is fine to drink and the spoon might need to be Kashered before further use.
If the coffee was heated in that mug and is still hot, then we're back to the regular rules of YD 94: if the spoon wasn't used for hot meat in the last 24 hours then the coffee and coffee mug are kosher, and if the spoon was used for hot meat in the last 24 hours then the coffee and coffee mug are only kosher if the volume of the coffee is 60-times (some say it's [sixty times the number of times the spoon was dipped in]-times) the volume of the part of the spoon dipped in the coffee. Either way the spoon must be kashered.
(These are some primary sources. CYLOR with the details of any actual case as there can be many ways things might differ from the positions and cases mentioned here.)

Putting meat spoon in dairy coffee


Looking for a program that will get System Specs over the network

Question: Looking for a program like Speccy, But one that I can run over the network without having to install / run it on each individual machine.
Answer: I use both Spiceworks (free, web based) and PDQ Inventory (free and paid versions, desktop app) for scanning on my network.
No matter what solution you pick, you will need to open ports on the clients' firewalls, usually the WMI ports.
Comment: I've briefly used spiceworks before for monitoring Switches and file servers, will it allow me to get system info from machines? eg. ammount of ram, gpu installed etc.. similar to speccy? I'll check out PDQ now as well, thanks for your answer
Comment: Yes it does. Even motherboard information, including bios versions and service/asset tags
Comment: Brilliant i will invest more time into it so, thanks again!


Manland and Sentinel of the Eternal Watch

Question: Sentinel of the Eternal Watch says, "At the beginning of combat on each opponent's turn, tap target creature that player controls."
Can the opponent activate a manland after this ability and attack with it to prevent getting the manland tapped?
Answer: Yes, you can get around the Sentinel this way with a manland. I'll assume you have the Sentinel, and your opponent has an untapped Mutavault.
At the the Beginning of Combat step in the Combat phase, all abilities that trigger at that point go on the stack. As part of putting the abilities on the stack, you have to choose a target, and that target must be a creature at that point per the ability text. So, by the time that ability's on the stack, the target is set, and can't be changed — and it isn't the manland.
Then, the active player, and the non-active player, will each get priority at least once. Your opponent can activate their Mutavault's abilty while the triggered ability is still on the stack, or they can let that triggered ability resolve and then activate their Mutavault. (The latter is probably safer, in case you have something like Redirect, such as the standard-legal Insidious Will.)
Then we move on to Declare Attackers, and their Mutavault is a Creature at this point, not tapped, and able to attack.
Answer: Yes, your opponent can do that.
The Combat Phase consists of 5 steps: Beginning of Combat, Declare Attackers, Declare Blockers, Damage, and End of Combat. Entering each step causes certain abilities to trigger and those abilities will go on the stack before anyone has priority to make plays. Sentinel of the Eternal Watch's ability will trigger during Beginning of Combat, then the active player (the player whose turn it is) will gain priority and try to respond to that ability while it's on the stack, followed by the non-active player. If each player passes priority, the ability will resolve.
After the ability resolves, priority will go back to the active player, then non-active player if the active player passes priority to make a play. During this period in Beginning of Combat is the latest possible time that a player with a manland could activate its ability to become a creature that could participate in being declared an attacker. During the Declare Attackers step, attackers must be declared immediately, then players will receive priority after that.


Pass jQuery slider variables through to Laravel controller

Question: Currently, I am using the jQuery slider with range. What I want to do is, upon the user submitting the form, I want the two values (max and min) to also be sent over to the controller, so I can save them in the database. They are both currently saved in the variable values:
  $(function() {
    $( "#slider-range" ).slider({
      range: true,
      min: 0,
      max: 1000000,
      step: 10000,
      values: [100000 , 300000 ],
      slide: function( event, ui ) {
        $( "#amount" ).val( "£" + ui.values[ 0 ] + " - £" + ui.values[ 1 ] );
      },
      stop: function(event, ui) {
            var values = $( "#slider-range" ).slider( "values" );
          }
        });
    $( "#amount" ).val( "£" + $( "#slider-range" ).slider( "values", 0 ) +
      " - £" + $( "#slider-range" ).slider( "values", 1 ) );
  });

I have alerted the variable and it echos the correct two variables. I am at a complete loss as to how to get the two variables, possibly split, over to my Laravel controller, once the user submits the form.
I usually get the form's variables through the Input::get method:
$id = Input::get('id');

But trying to access this variable always returns NULL
Any help would be hugely appreciated.
Answer: Here is a jsfiddle of how to get it working properly. My guess is that you forgot to set the "name" attribute on the HTML input field.


Can I use individual wires in PVC conduit for just a portion of a kitchen circuit?

Question: I was planning on running 2 black 2 white and 1 green 12 gauge wires through flex from panel to kitchen wall, then changing to rigid pvc to go under ground to kitchen island for microwave and gfi circuits but the project manager insists I use cable until I switch to pvc because of cost. I didn't realize it would save that much money and prefer not having unnecessary junction boxes. so I just thought I'd ask if there were any potential issues before doing it his way. Thank you.
Comment: Why not run NM-B (romex) direct to the island?  Is there exposed wire inside cabinets?  Where on the planet are you (country)?
Comment: Project manager doesn't want to buy any THWN wire.   Buy your own THWN wire in a rainbow of colors, blue/gray for the second circuit so you can tell it from the first circuit.  Gray is a legal neutral color and any electrical supply will happily sell you those colors.
Comment: @Tyson The kitchen sits on a slab, so it was necessary to use rigid and thwn from wall to island. No exposed wire inside cabinets. I'm in southern California.
Comment: @cdguitarok putting that fact in your original question would have gotten you a faster answer.
Answer: In answer to the question you asked in your title. There is no issue with changing from a cable (romex) system to a conduit system just so long as it is done properly.
FYI - The difference between a cable system and a conduit system other than initial cost is that a conduit system is more flexible when it comes to upgrades, remodel or repairs. For example, you have a receptacle burn up and it also damages the conductor far enough back you can't make a splice to repair it, with a conduit system you simple go back to the next junction and pull a new conductor. If you have a cable system you will have to open the wall up to replace the cable.
Running PVC to the island and installing conduit and conductors is a good idea since it allows you the opportunity to replace or modify your circuity to the island without cutting up your finished floor. Most houses in the US are normally run in Romex because of the initial cost and electricians are trained to deal with the problems they may cause down the road.
Hope this helps.


Bring wine from Europe to Asia

Question: Next month I'll be flying to Philippines with my family and since is not usual to find wine in that country, we thought we can bring our own wine (wrapped and protected) on the checked luggage. Is there any problem with that? do I need to declare it? We are thinking of a couple of 750ml bottles per person.
Comment: Will it push you over the weight limits for your checked bags? What are the duty free limits for alcohol for the Philippines?
Comment: There's no problem with the weight. I'm just afraid there might be any rule about alcohol/wine that I don't know, and I don't want to put neither me or my family in that situation.
Answer: I believe you'll be able to take 2 bottles with you.
According to World of Duty Free (who are one of the big UK airport based duty free companies, so ought to know...)

The following items may be imported into the Philippines without incurring customs duty:

(snip tobacco bits, not relevent)
2L of alcoholic beverage, in bottles of not more than 1L each.

Wine normally comes in 750ml bottles, so two bottles takes you to 1.5l, three bottles would push you over the limit at 2.25l.
I think those limits are per person, and can't be shared. So, if there were two of you, you could take 2 bottles each, to a total of 4 bottles. I'm fairly sure that two people wouldn't be allowed 5 bottles, as while that'd be 3.75l total you can't normally pool your allowance like that.
(The official Philippines Bureau of Customs website says "Liquor and/or wine: two (2) bottles" with no mention of bottle sizes, so I'd suggest going with the lowest option from the two different sources, and say it's 2 bottles of wine or spirits per person, max bottle size 1l, hence 2 750ml bottles of wine per adult travelling)
Otherwise, for taking bottles, they can't be in your hand luggage due to current hand luggage restrictions. They need to go in your checked luggage. Firstly, make sure they won't cost you too much - bottles of wine are rather heavy so it might push you over your weight limit. Otherwise, place them in the centre of your suitcase, and make sure they're both well wrapped with soft material to cushion them against blows, and are in a sealed bag in case of problems (you don't want the rest of your suitcase covered in wine!). If you have two bottles, wrap them individually, so that they can't knock and break against each other. If the bottles are well padded, and in the middle of the suitcase so surrounded by other squishy things like clothes, then you ought to be fine.
Comment: Usually the duty free shops in airports sell one ltr bottles...
Comment: Duty Free shops normally sell spirits in 1 litre bottles, but wine is almost always still in the usual 750ml bottles
Comment: Thanks for the answer. so definitely it's legal two bottles of wine. On arrival should I declare I have to bottles or just go out normally?
Comment: No idea, sorry, I've never been. Depends on the setup at the airport. Most places don't ask you to declare your duty free, but if that's needed it should make it clear on the immigration/customs form
Comment: You are correct. As long as you fill out an honest declaration, customs here will go out of their way to help you. They're out to stop those that go to places where expensive bottles can be purchased at a deep discount and come back with a suitcase full to sell locally without paying import tax.

Bring wine from Europe to Asia


Why are people creating so many coins and can all of them sustain?

Question: I wonder why people are creating so many crypto currencies and how many of them may sustain? Can anyone here predict what is going to happen? (Not asking to predict what coins are going to sustain as no one would know answer to that).
Answer: Many other crypto currencies are inspired by bitcoin, but have a goal that differentiates them from bitcoin. For example, litecoin was design to combat the development of ASICs, so that people with regular computer hardware can mine them. Namecoins provide secure key-value pair storage, and devcoins are somehow used to fund open source endeavors. Others just want to piggy back on the success of bitcoin.
The success and sustainability of these other currencies (often called altcoins) depends on whether or not you can convince others that they are valuable. For example, Namecoins are gaining popularity because you can buy .bit domain names with them.
Many altcoins will likely remain worthless forever, but people will assign a value to some, and those may be sustainable.
Answer: Also,basically,the creators of the new coins are hoping that they will become popular so that they can sell their coins for a profit.
Comment: True that they are hoping for their coins to become popular. But what will be the reality? If every coin going to succeed, then everyone start their own. So just wondering how many of them going to survive (5 or 10 or 15?)
Answer: Many altcoins will likely remain worthless forever, but people will assign a value to some, and those may be sustainable.


How does the browser decide to accept a self-signed certificate?

Question: As far as I know, with OpenSSL, you can self-sign your website's certificate. This means that the browsers that will connect your server are supposed to be willing to accept a self-signed certificate for your website. My question is, how does the browser know whether or not to accept a self-signed certificate for a particular website? What if I MITM a client and present a self-signed certificate for a bank website? How does the browser not get tricked at that point?
Comment: Hello, have you tried doing this yourself? You will find that you get a warning/error page. Browsers don't trust certificates unless they are signed by a CA that the browser trusts.
Answer: Browsers will only accept an invalid certificate - and self-signed is one form of "invalid" - when the user acknowledges the risk and overrides the browser.  The specific steps for doing so vary from browser to browser, but they're usually onerous by design - they want the decision to bypass security to be hard, not easy.
Comment: Technically a self-signed certificate isn't automatically invalid (after all, all root certificates are self-signed), but because it's signed by itself it won't be *trusted* unless the browser has been pre-configured to trust that particular certificate. Which is not going to be true on an arbitrary user's system for a new self-signed certificate you just created.
Answer: Browsers will alert the user if they are presented with a self-signed certificate which they don't trust.
The browser user or system administrator should preempts this scenario and add the self-signed certificate to the browser's trust-anchor store beforehand.  That way, the user won't see a warning.
Done this way, users can be informed that if they ever see a browser warning they should stop browsing and report it.
Instructing users to simply bypass the security alert shown when an unknown self-signed certificate is presented by a server means that in the event of a real MITM attack the users will do exactly as the attacker wants them to do and simply continue to the site.
Answer: By root certificate which is included in each browsers already.
There are lots of root certificate in browsers, and it is referred in every TLS or SSL session using chain of trust. At last, the root certificate in TLS/SSL session is verified if the root certificate is installed in the system, browser.
If a user/admin insert the self-signed root certificate in the system or browser, it will work well.
https://support.globalsign.com/customer/portal/articles/1211541-install-client-digital-certificate---windows-using-chrome
It means that the list of root certificate is important for securing TLS/SSL. Hence, mozilla and android and most browser related organizations maintain the list of root certificate.
https://www.digicert.com/blog/official-list-trusted-root-certificates-android/
https://wiki.mozilla.org/CA/Included_Certificates
CTS(Compatibility Test Suite) for android enforce the list, it means that if any not permitted root certificate is included in factory phase, google cert. would be not issued.
https://android.googlesource.com/platform/system/ca-certificates/+/android-cts-8.0_r5
Answer:
What if I MITM a client and present a self-signed certificate for a
bank website? How does the browser not get tricked at that point?

Hopefully the certificate would have name constraints that would prevent it (or any certificate signed by it) from applying to arbitrary domains. (Sadly this is not the typical case, so an attack of the type you describe would likely succeed if you could intercept the traffic.)


Ubuntu freezes a few minutes after login

Question: I use Ubuntu 15.10 (running from the disk) I run diagnostics and the disk doesn't seem to have any problems nor my drive should have (it and "expensive" bd-r DVD-r drive from a big brand and never had issues in the past or in windows I also tried to use a second drive without any difference)
I loads the GUI am able to do whatever install I want or run what I want without a problem but then after some random time interval everything freezes the mouse doesn't move the keyboard doesn't react (caps lock etc when push doesn't flash any LED, etc.) and the only solution is hard reset
My CPU is AMD FX 8320, my mobo ASRock 970 pro 3 rev 2.0, 16 GB of RAM, Nvidia GTX 650 ti 2GB RAM. I also run 2 monitors.
It must be Ubuntu and not a specific task or process (like flash) because it freezes even if I don't do anything (like being afk and returning after a few minutes only to see that it froze... )
In fact I never shutdown the computer because EVERY time I boot Ubuntu it freezes... its got so frustrating that I want to hammer my tower to pieces no matter if I know that its not likely a hardware failure.
I installed Ubuntu to a CompactFlash card. It was disastrous! It was slow as hell the boot time took longer than the DVD and the system open error messages after log in and hang itself, and I was surprised since using Knoppix on CF card was like I was using a PCIm.2 SSD like super fast with no errors. Even Windows 2000 is super fast using a CF card.
Then I tried installing it on a 32GB usb3 flash drive and the problems still exist although after the initial installation and first boot it was stable for quite a few hours like more than one or maybe two. It never happened with live DVD which did freeze on random times, but usually if not always it took less than a hour.
but it freeze nonetheless (I was running and update check which took like 30 minutes to an hour+ despite my fast internet connection -VDSL 30Mbit, downloading at ~3MB/s- it finished downloading the files I think and it froze when unpackaging was like at ~90%)
And it was generally VERY slow (not so horribly slow as the CF which too like 20 seconds to click on log in other 5-10 to blink the cursor on the pass entry etc) it had like one to five+ delay to respond to most of my actions (sometimes it was instant but very rarely)
Again I was surprised... I expected much better (since using the same stick for Windows usually instantly responded to read and write of large files and read writing speed was more than 80MB/s )
I left it open frozen as is because of frustration and gone to sleep next day (today) I shut it down and boot it up again and it was much faster (although not even close to Knoppix running on CF) it was like having a HDD/SSD hybrid, but now it froze like within a minute after login. Then I hard rebooted it and SURPRISE it booted normally I tried to update the AMD microcode and the Nvidia driver before even being able to click on "Apply" after choosing them
It froze.
Then I rebooted again trying to do the same thing it worked. Then I restarted the system normally by clicking shutdown and restart (for the first time)
but during the restarting it froze before loading the GUI with a console error like: /dev/mapper/something-vg-something clearing this and that or something like that then after hardreboot I run ubuntu recovery and it loaded shell on the same place (after telling me that this thing on the mapper directory wasnt found - sorry just woke up can't remember.) then I rebooted
and surprise it worked.
Now typing this message trying to be hasty while nervous of a sudden freeze again (sorry for the typos and for the long post cant think clear right now)  but... and Ubuntu froze before I was able to finish the sentence. Hopefully Stack Exchange saves the text.
Answer: I have had a similar problem, and the only thing that works for me is running an older kernel. There is a list of stable kernels here: https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
I have been using 3.19 without any problems.
Edit:
Here is a previous related question: How do I install an old kernel?. The answer describes how to install an old kernel.
Comment: Please provide the instruction to do so


What Happens To The Melody When Played In A Different Key

Question: What happens to notation (e.g. a melody line) when a tune is played in a different key than the one it was written in?  Do the notes alter in any way or do they always stay the same as originally composed?  In other words, if a tune was written in the kay of C and the melody begins with a C note followed by a D note, does that pattern of notes change to a different pattern, if the tune is played in a different key?
Comment: If the notes stayed the same, what difference would a key change make?
Comment: On a piano or saxophone for instance, the notes are different and the fingerings are different.   On a guitar you just move up or down some frets and the fingerings are the same (or a capo is used).
Answer: This is called Transposition.
For instance, if you are in C major and have this melody: C-F-E-G-C and you move to E major scale, the melody would be: E-A-G#-B-E.
You have to keep the intervals the same (A perfect fourth remains a perfect fourth etc), but the notes change.
Comment: It's called [transposition](https://en.wikipedia.org/wiki/Transposition_%28music%29), not modulation.
Answer: There's two issues here:  what happens in music NOTATION, and what happens in the MUSIC, when you transpose to a different key.
The short answer on the music notation is that the pitch intervals from note to note of a transposed melody don't change when you change the key, thus for example if you had a melody in the key of C, starting on the note E, then transposed that melody TO the key of E, then you'd write the key signature of E (four sharps), and your starting note would be a G#, but you wouldn't have to write the sharp, because it's in the key signature already.  If there were no accidentals (sharps/flats) in the original melody in the key of C, then there would be no accidentals in the transposed melody, (beyond the four sharps of the key signature).  If you had, say, a written note Bb in the key of C, when transposed to the key of E, that would be written as a D-natural, instead of a Db.
Now...there also ARE differences in tonality from key to key.  Those differences are extremely subtle, tiny, but they're there.  In other words, Nigel Tufnel wasn't completely blowing smoke when he declared that "..D minor is the saddest of all keys..."
Comment: Whether there are differences in tonality depends on the instrument and the tuning system it's using.
Answer: Seeing as Major scales have semitones all in the same place transposing between different Major keys will still garner similar (If not identical) general Major tonality.
You often want to do this for practical considerations. Guitar music that is not written specifically for guitar almost always has to be transposed either to E / A or D.
This does not take away from the music if done correctly.
Comment: Can't agree that 'guitar music almost always has to be transposed either to E/A or D'. That's absolutely not true. The key that the vocalist is happy with has a far greater influence on the key. Music not specifically written for guitar can usually still be played in its original key on guitar - or most other instruments.
Comment: Those are the natural guitar keys. You want the root note of the chord in the bass.
Comment: @NeilMeyer: Can you provide more evidence for this?  Maybe a link with some explanation?  Granted I didn't study guitar for very long, but in my limited experience keys were all over the place. G in particular was very common and natural, since it allowed playing 1/4/5 chords (or at least variations) with minimal movement.  I just question your statement.
Comment: You only ' want the root note of the chord in the bass' if you're a basic guitarist.  A good player will be able to play in any key.
Comment: For songs in a major key with the occasional chord from the relative minor, the easiest key on guitar is G! Still, what the vocalist wants is way, way more important, like Tim said. I've also had to change key for tin whistle: not for lack of whistles, but because the F whistle was too strident we changed to D.
Answer: On the piano today you'll get only the sound of your melody or harmony higher in pitch (minus different resonances of the instrument itself). This is so because the piano is tuned equally (bad) ie. all keys sound the same. This is called equal temperament. Some people think it is bad because one could say only octaves are pure, the rest is an approximation.
Before 1900s it was common that different keys sounded different because of so called temperaments. Even earlier the keys were very distinct sounding (mesotonic tuning) because the main key was meant to be pure. This of course made composing restrictive.
Roughly saying claviers then were tuned so that major thirds were pure, later it was important to have pure fifths. The claviers/piano's themselves changed dramatically as well and had to be tuned differently. Thus tempered temperaments became fashion. Today's piano's have a more bell like sound, in the upper registers.
One notable composer named Johannes Sebastian Bach was especially interested in finding temperaments for the clavier (Bach's well tempered clavier) because he wanted to continue a piece in as many keys as possible without sounding (too much) out of tune.


mean of wavelet for image processing

Question: For many papers which talks about using wavelet transforms for feature detection in image processing, it is stated that it is advantageous for the wavelet to have zero mean? Why is this so? Thanks in advance.
Comment: Please see question and answers in http://dsp.stackexchange.com/questions/14199/gabor-filters-for-digital-image-processing/14201 (gabor filters for digital image processing)
Answer: Please consider that the wavelet transform coefficients represent the local details of the signal. In (incomplete) DWT or a Gaussian pyramid, there is also a trend signal after the transform that contains the global behavior.
The first condition on this local-global separation is that constant or near constant parts of the signal get mapped to zero in the local details. The scalar product of a (wavelet) function with a constant function gives its DC contents. So DC of wavelet equal 0 means that the computed coefficients are high at regions of interest like edges.
The same goes for higher moments. If one wants to regard slow linear or quadratic "gradients" in the signal as not essential for the contents, or as part of the trend signal, then the first resp. second moment of the wavelet must vanish.

Or to consider it from a slightly different angle: Each scale of the wavelet transform corresponds to the application of a high-pass filter. One defining property of a high-pass filter is that the amplitude response around the frequency zero is small, ideally zero. Vanishing moments of the wavelet function correspond to a flat graph of the Fourier transform of the wavelet at frequency zero.
Comment: Very nice theoretical analysis, but can you add some formula, and/or figures to better illustrate it?
Comment: @LutzL:  For image processing applications, what detrimental effect does it have if the DC of the wavelet function is not zero? It's best if you can show some equations to make it mathematically sound.
Comment: The nice images are in the link in the comment to the related question, especially the cat image. The question was for a quality, the zero DC of the wavelet function, I'm at a loss to add quantitative formulas (without replicating wikipedia articles or text books).
Answer: It is advantageous for a simple reason:

The DC component carries little information for signal processing.

(well, you can find counterexamples - but from my experience, they would weight 0.01%)
Indeed, the mean of wavelet coefficient, when convolved with an image, would transfer to this mean times the DC component. Having this information in your wavelet coefficients vector would just add some redundant, mostly uninformative bias.
Comment: Hi @meduz: Thanks for your answer. Can you show your reasoning mathematically?
Comment: You can find counter examples (like if you want to use the average value in your vector of coefficients) so there is litlle proof to do mathematically. What you can do is to look for the prior distribution of coefficients in the signal versus noise.

mean of wavelet for image processing


What would be the implications of mistakenly adding bias after the activation function?

Question: I was looking at the source code for a personal project neural network implementation, and the bias for each node was mistakenly applied after the activation function. The output of each node was therefore $\sigma\big(\sum_{i=1}^n w_i x_i\big)+b$ instead of $\sigma\big(\sum_{i=1}^n w_i x_i + b\big)$. Assuming standard back-propagation algorithms are used for training, what (if any) impact would this have?
Answer: Let $L(\mathbf{w}, b) = \sigma \left(\sum_{i=1}^n w_i x_i \right)+b$, then the partial derivative of $L$ with respect to $b$, in Leibniz's notation, is $\frac{\partial L}{\partial b} = 1$. Let $L(\mathbf{w}, b) = \sigma \left(\sum_{i=1}^n w_i x_i + b \right)$, then the partial derivative of $L$ with respect to $b$ is $\frac{\partial L}{\partial b} = \frac{\partial L}{\partial \sigma} \frac{\partial \sigma}{\partial b}$.
So, in general, the partial derivatives with respect to $b$ would be different in these two cases, thus, in the gradient descent step, $b$ would be updated differently in both cases. In practice, it may or not affect the performance of the model, depending on the importance of the bias with respect to the given problem. Read this answer to understand the role of the bias.


Booting server from grub2 make changes persistent

Question: I have tried switching my server to a different kernel from what my hosting provider supplies. It should just be a case of updating the kernel from the hosting providers management pages, reboot and the default CentOS kernel is used. This has worked on 1 server but not on the other.
On the broken server it just boots to a grub2 menu. I've managed to get it boot again by running the following:
set gfxpayload=text
insmod gzio
insmod ext2
linux16 /boot/vmlinuz-3.10.0-693.5.2.el7.x86_64 root=/dev/sda ro crashker
nel=auto rhgb console=ttyS0,19200n8 net.ifnames=0
initrd16 /boot/initramfs-3.10.0-693.5.2.el7.x86_64.img
boot

I took these by looking at the /boot/grub2/grub.conf on the server that did work without issue.
After doing the following the server succesfully boots up, but the changes aren't persistent, if I reboot I'm back to the grub2 menu and I need to do it again.
I've looked around and saw some places say to run update-grub but I don't have that command.
I also found to try the following:
grub2-mkconfig -o "$(readlink /etc/grub2.conf)"

This just seems to print the script out and doesn't do anything. If I reboot again I'm back to the grub2 menu.
Anyone got any ideas on how to resolve this.
I'm running CentOS 7 and the kernel is now on 3.10.0-693.5.2.el7.x86_64
Thanks for any help you can provide.
Answer: I found out I should have run grub2-mkconfig -o /boot/grub/grub.cfg to save the changes instead.


How often do jet-liners have touch and go landings?

Question: I read that a go around is 1-3 out of every 1000 and I wondered how rare it is for a large commercial plane to actually hit the runway before deciding to go back up again.
Comment: I've done approximately 45 in one B737 in a single day once, but that was a rare occasion of pilot training (I was a guest/observer).
Comment: The decision to go back up again is usually made before the aircraft touches the runway. Making the decision to go around after the wheel touch the ground is dangerous because of automatic spoiler deployment and autobrakes which make going around difficult. See for example [EK521](https://en.m.wikipedia.org/wiki/Emirates_Flight_521). Pressing TO/GA before touching down switches the autospoilers and autobrakes off, so a touchdown after the decision is not so much of issue, yet still a very rare occasion.
Comment: @DeltaLima, Not to mention that many airline's SOPs require full brake and tire inspections after a go around after it's hit the deck! One Australian airline even requires the wheel and brake assembly be removed, delaying flights and ops.
Answer: Quite rare.
An approach abort that results in touchdown is called a "balked landing" and generally happens when you've started the landing transition, reducing power and starting the flare, where you are in a "low energy state" (speed decelerating below Vref and engines going to idle) at the time you make the go-around decision.  It's considered a high(er) risk maneuver like high speed rejects on takeoff, because at that point you are likely going to touch down, however briefly, whether you want to or not.
Normal missed approach go-arounds happen mostly because of weather where the runway environment wasn't visible at minimums, and maybe occasionally from a runway incursion that is noticed early, or something like a report of a flock of birds in the way, which would be most of those 1-3 per 1000 landings.  They happen at at least a hundred or couple hundred feet and usually don't involve actually touching down.
A balked landing will generally only be for something like a runway incursion at the last second, leaving you with a situation where landing and rolling out is obviously more dangerous than going around because you are probably going to hit something on the runway, and they are pretty rare events.  Balked landings are usually special maneuver covered in the initial type course and may be included in recurrent training.
Comment: Way more information than needed.  The poster mentioned T&G in the question, but the body was clear he was asking about go-arounds that involved ground contact. It's not a light aircraft thing.  I've done balked landings in sim training in jets (RJs).  It's a dedicated procedure, separate from the normal go-around routine and affects big airplanes with lots of inertia and laggy power response.  I couldn't find any data on balked landings vs missed approaches,so tribal knowledge is all there is to go on.  Admittedly the "rare" bit is what I would call informed opinion but that's all there is.
Comment: Your assertion of "rare" is generally true, in my opinion, but some stats, outside sources, or even a validation of your industry expertise would improve your answer. Most of what you offer holds true for the light aircraft fleet, apart from intentional touch and gos, but maybe less true for the "jet-liners" in question. In my first and second hand experience, I would suggest automation or guidance issues, unstable approaches, gusty winds, and missed approaches during auto-land to be factors that figure largely in unintentional touch and go landings.
Comment: Industry personnel would have access to actual data to be able to answer this question with specificity, though the data itself may be protected or confidential.


Hydro-pneumatic fuel controls and hydro-mechanical fuel controls

Question: What are the advantages and disadvantages of the hydro-pneumatic controls against the hydro-mechanical controls?
Answer: They are actually the same thing. Hydro mechanical fuel controls often include the use of pneumatic pressure to regulate the fuel flow. Here's an example of a simple one: http://blog.covingtonaircraft.com/wp-content/uploads/2015/08/fuel-control-unit-pt6a.gif
The mechanical part is the input of rpm by a shaft connected to the compressor spool. The pneumatic part is the P3 (compressor exit pressure) input.


How can I remove residual adhesive that may contain asbestos from wood?

Question: Our house has two bedrooms in which the previous owners installed vinyl tile over wood flooring (how ironic is this: it's wood-grained pattern tile over beautiful, real wood).  We want to remove the vinyl tile, then refinish the floors.  The tile itself comes up without any effort at all, but there is residual adhesive still attached to the wood.  I'm concerned it may contain asbestos.  Assuming it does, what's the proper method for removing the residual adhesive from the wood before I refinish the floor?  The Residual Flooring Covering Institute's (RFCI) guide for removing residual adhesive from wood is to remove the wood - not my preferred option.
Comment: Is it that black tar stuff? There's a specialty product for that (and it still sucks).
Comment: What makes you think it may contain asbestos?
Comment: It's more likely that the tile contains asbestos than the adhesive.
Comment: Totally legal for a homeowner to remove asbestos here in WA, but I'm sure the majority of homeowners don't even think of asbestos when tearing out flooring.
Comment: My original question about asbestos is because I haven't read how to prepare a sample of just the adhesive, and not the adhesive/tile combined.  The adhesive doesn't seem to be cutback, however.  I'm guessing this install was a hack job by the previous homeowner.  The hardwood underneath was not prepped beforehand - it wasn't sanded, and the varnish is still intact for the most part.  I'm honestly wondering if they put this stuff down with wood glue - seriously!  That would be awesome, but until I can say "this doesn't contain asbestos," I'll assume it does.
Answer: First, I agree with diceless, it is probably perfectly legal for the homeowner, to deal with this problem himself (assuming no part of the house is rented to a third party).
On the other hand, I agree with Mazura, you may be opening a huge can of worms here.  Since we are only talking about 2 bedrooms, I have to question the cost and time effectiveness of trying to rehabilitate the wood if the cutback contains asbestos.  I realize there may be problems matching the height of the bedrooms to the hallways or other areas, but if there is asbestos (and the floors are flat enough as is), just nail down new 3/4" hardwood or good quality 1/2" engineered hardwood over top of the existing floor.  Just use a heat gun to remove the excess cutback to ensure the floor is flat enough.
If the cutback does not contain asbestos, remove excess cutback and then go at it with a drum sander (rent it at Home Depot or wherever).
If a home sale is in your future, I realize you may not really want to know whether the cutback has asbestos since if you do, you'd be obliged to disclose such on sale. But until you know, you can't really plan the right course.  You should be able to scrape up a sample of cutback, mail it to a lab and get results in less than a week.  e.g. http://www.asbestos-test.com/
Comment: single family homes are not regulated federally, but they are regulated locally.  You need to find out what your local regulations are.
Answer: First, test the adhesive.  If it does have asbestos, you are stuck.  If it doesn't your life is going to be easy.
Here is the reason why they recommend complete removal of the wood.  Asbestos removal requires two things:  Enveloping the entire area, basically making a sealed air tight work area that can be removed once work is done.  This would be walls and ceilings covered in plastic, all seams tapped.  Double sealed barrier for your one entrance/exit.  This really isn't the deal breaker.  The next requirement is...  Wetting.
Any time asbestos fibers have the possibility of becoming airborne, the entire work area needs to be wetted to prevent this from happening.  Can you imagine using a power sander on soaking wet wood floors?  One, the wood would be destroyed.  Second, you might never get to see those destroyed floors because you're dead from electrocution.
If you truly do have asbestos in the adhesive your two options are removal of the wood or encapsulating it (lay another floor on top).
Answer: Avoid the dust of sanding: use Citristrip Gel. It's an orange color in a plastic bottle.
Get a quart, an 85¢ throwaway brush, a 4 inch scraper (I prefer steel), a 1 inch putty knife, and a cheap plastic bucket. Put the gel on at least an eighth inch thick on a square foot and leave it for 18-20 hours. It should easily scrape off.
Comment: The citric remover will leave a permanent contamination in the floor possibly damaging future adhesives


Conservative / Nusach Sfard

Question: Are there any Conservative synagogues that daven Nusach Sfard?
Comment: Sephardic, or Nusach Sefard (closer to Hasidic)?
Comment: Yosef, Welcome to mi.yodeya, and thanks very much for the interesting question. Please consider clicking "register," above, to create your account. That will give you access to all of mi.yodeya's features and will allow you to take full credit for your contributions.
Comment: PS: I merged in your previous incarnation. If you register, the system will keep track of you by sign-in rather than IP address, so that won't be necessary.
Comment: Shalom: I was thinking of the latter. But it was interesting to read about the former, below.
Answer: As already mentioned, the "official" Conservative siddurim use a slight variant of nusach Ashkenaz (the differences are not that great).
However, I have been in some "Conservative-like" (though officially unaffiliated) congregations that use nusach Sefard. These are, as you suggest, descendants of Orthodox congregations that once used this nusach. The congregations I am aware of use the Birnbaum siddur or a related older siddur.
Comment: Jordan, Welcome to mi.yodeya, and thanks very much for contributing your experience. I look forward to seeing you around.
Answer: The conservative movement uses a variant of Nusach Ashkenaz with some small changes (in terms of the percentage of the text changed), to express some rather large philosophical differences from Orthodox Judaism.
However, there are some Conservative-affiliated Sephardic synagogues that are egalitarian, but use the Sephardic nusach. These synagogues are thankfully the exception among Sephardim, rather than the rule.
Comment: Where? I've seen some fairly liberal Sephardic synagogues (the most you get is no mehitza and affiliate affiliation with Conservative affiliate groups, e.g. Sisterhoods and Men's Clubs and USY), but they've never associated wit the USCJ.
Answer: The conservative have their own Nusach
Comment: There's a fairly large shul in my area which was once Nusah Sefard before it became Conservative. It's got some remnant practices, such as Sephardi haftarot, Mizmor Shir leYom haShabbat before Torah reading, and Ashrei/Uva leTzion before returning the Torah on Mon/Thurs, but otherwise it uses the Sim Shalom text exclusively.
Comment: Yes, I know, but it is based on the Nusach Ashkenaz. What I was getting at, though, is that since there were many cases, circa 50-100 years ago, of once-Orthodox shuls that came to affliate with the Conservative movement. It stands to reason, then, that some were originally Chasidic/nusach Sfard and may have kept some of their original customs. I was asking if anyone could confirm.
Comment: @B.BarNavi (I had to [check](http://meta.stackexchange.com/questions/43020) how to write that so that you'd get notified*), this looks like an answer (and a good one: it's an actual instance of a Conservative synagogue that, partially, uses _nusach S'farad_; it'd be even better IMO if you mention what synagogue this is). Perhaps you should post it as such. (*You might wish to change your username so people know how to `@`-notify you, as otherwise you may well miss responses to your comments.)
Comment: Why this is the case I don't Know But it seems that Sfard does not Work for all the off shoots of Judiasim.The Conservative siddur, Siddur Sim Shalom is also Nusach Ashkenaz. To the best of my knowledge, the Conservative Movement simply doesn't use Nusach S'fard. Even the Reconstructionist Movement, which is an offshot of the Conservative Movement, uses Nusach Ashkenaz, and, for that matter, I think the (North American) Reform Movement's prayer books are also Nusach Ashkenaz. Nusach S'fard seems to be the exclusive province of certain Orthodox communities, at least in North America.

Conservative / Nusach Sfard


Which one is appropriate: much or many?

Question: Should one say: "She knows much more people than me" or "many more people than me?"
Comment: Strictly speaking I think only ***many*** is "correct" in your exact context (because ***people*** is an "uncountable, mass noun", as in *She has much more **money** than me*, not a normal "countable" noun as in *She has many more **siblings** than me*). But in practice I wouldn't call it a serious error to get this one wrong - many native speakers might make the same or similar "mistakes", and I'm sure there will be at least some contexts where ***much more*** and ***many more*** are both considered "acceptable" and equivalent by many native speakers.
Comment: (...in which context it's worth noting that [***fewer and fewer***](http://www.grammarerrors.com/grammar/lessfewer/) people take any notice of grammarians arguing over the acceptability of ***less and less*** people. So don't spend too much time on this issue; it's as much about pedantry as it is about actual usage and/or useful grammatical principles.)
Answer: "People" is here functioning as a plural noun, and so it is countable. "Many more people than me" is undoubtedly correct.  Sometimes you will hear "much" being used with countable nouns, but some people consider this to be an error. However, both "much" and "many" would be understood in this context.

Which one is appropriate: much or many?


Saving .so file in IDA

Question: I have edited .so file in IDA. I don't know how to save it. Any idea for saving them?
Answer: Go to File and select Script file and choose a .idc name for your file, which makes the changes permanent.
Then when you will run the .idc file, you will notice that bytes have been written to those segments successfully.
After that, IDA will ask for saving the new binary file.
Comment: Thanks for the quick reply. I can see the script file and script command. I choose script file and its asking me to select run file ! i am stuck with this. Please clear me !
Answer: To apply the changes you made in your .idc database to the original program, use the menu: Edit/Patch Program/Apply Patches to input file.
Warning: If you make several patches, apply them, undo one of the patches, and apply patches again, ida will have lost the information about the "undone" patch and not undo it in the original file. Because of this, you should make a backup of the original file before your first patch, and copy it back before every subsequent patch you make.
Also, i recommend you to check into idapatcher which will make it a bit easier to make and check your patches.
Comment: Helped me a lot! Vote up! :)

Saving .so file in IDA


User research on 100 people

Question: Has anyone ever conducted user testing on a mobile app or service with a large amount of people? (around 100 people). We plan to give the users the application and have them use it for 1 week. It would be great if anyone could give me some pointers for preparing and conducting the study.
Comment: Hi Richard, you don't give much information about how you intend to conduct the study: eg feedback form, survey, face to face, location... or maybe that's what you want to know? Knowing more detail about what you know already will help others advise you in a more relevant way.
Comment: You might want to run a small trial first to get some ideas on what to ask your larger sample.
Answer: I'd suggest that the main aspects you want to address with such a large group would be;

Ensure that you know what aspects of the app you are needing to test and that this is communicated to the testers. Since you do have access to such a large group of testers, it might be worth tasking them with testing different aspects of the app (broken down into groups of ~10) to obtain a more useful overview of different areas (Interaction, Process, UI etc.)
Make it easy for the testers to get their feedback noted, UX field testing is really useful but a lot of information gets lost between the user interacting with the app and getting this information logged. There is a useful collection of methods for field studies here - http://www.allaboutux.org/field-methods

Hope this helps
Answer: I have already conducted an usability test with 45 people. We split the participants up into 5 peer groups of 9. Each peer group tested the same software, but in a different configuration (configurations varied in the gui design, in the interaction flow or in the automation level for certain tasks). Thus we were able to compare statistically, which configuration was the best to accomplish a certain task. For comparison, we calculated different metrics for each group:

average time to accomplish a task in a certain configuration
task success of a group - how many people managed to accomplish a task?
average quality of the achieved result in a certain configuration - how good was the result (it depends on the task if a quality metric can be determined)

The more people you have in each peer group, the more reliable the statistics will be.
If there are any design decisions in your app, for which alternatives exist, you can find out the best alternative with the help of a big user test. Find out metrics to measure the convenience of each alternative and put together peer groups to test the different alternatives.

User research on 100 people


Is Ultron dead in the end of the Avengers 2?

Question: After the battle in Sokovia, the Vision and Ultron are talking. But when they are done the Vision shoots Ultron with a flash of light. But I don't think that kills Ultron. Also the Vision has 86% of Ultron's cerebral matrix and base consciousness in himself.
Comment: `"but I don't think that kills Ultron"` Why not?
Answer: It's a comic movie. With a comic character. Known for not being dead often. But official word is... exactly the same. He's dead until he's not.

"You know, for me, Ultron is really gone," [Director Josh Whedon] told Mashable during an interview at Disney's Burbank studios. "For me, that's the cut to the gunshot. That's him dead. But, I work at Marvel. So if I happen to see Ultron wandering around in another movie later on, I will be neither surprised nor at all disappointed."
But Ultron doesn't exist just inside a metal body; his programming has infiltrated the Internet itself. He has more than a few escape hatches.
"Ultron's famous for coming back," Whedon said. "I like to put a period at the end of a sentence, [Marvel] likes to add two more. You know, into an ellipse." (Joss Whedon is usually the last person to explain a joke, but we'll grant this.)
As for The Vision himself, Paul Bettany was equally equivocating in his assessment of Ultron's fate.
"One of the great things about the Marvel world is that it sort of doesn't matter," Bettany told Mashable. "They can figure out retroactively — if they want James Spader back, they can figure that out. I loved that last scene. It was really well-written, and we did it in 20 minutes as the sun was going down in a car-park."

Further more:

Whedon remains firm that his scene was indeed a killshot for Ultron — and at the same time, hopeful that it wasn't.
"Look, I think James is so phenomenal," he said. "I just have a huge crush on Ultron. And if he showed up in Infinity War, nobody would be more pleased than me."

Whedon is no longer directing Marvel's headline movie franchise, the Avengers. So if Marvel, or the Winter Soldier/Civil War directors Joe and Anthony Russo who are supposed to direct Infinity War bring Ultron back, well, that's (comic) show biz.
A prime example of Wiki: Comic Book Death or TV Tropes: Death Is Cheap, First Law of Resurrection,Back from the Dead and Reports of My Death Were Greatly Exaggerated
Keep in mind, Whedon killed Agent Coulson in the 1st Avengers movie, and is dead as far as the films are concerned. There's conflicting info on his status in the TV Show Agents of SHIELD, where he's no longer Dead. Ultron is fair game too.
Comment: @DrRDizzle i can't keep up with his flipflopping. But noted, and linked to.
Comment: Great answer apart from one thing - although Whedon did kill Coulson in *Avengers Assemble*, it's worth nothing that it was h who bought him back in *Agents of SHIELD*. Marvel Studios didn't ignore his decision to kill Coulson, they did go out of their way to allow him to create a show starring him.
Comment: @DrRDizzle also, did he actually die, then get resurrected by alien something, or was he healed by it before actually dying?
Comment: He actually died before being bought back by Project T.A.H.I.T.I., but it's worth mentioning (as I'm sure I have before) that Phil Coulson isn't dead as far as the films go - he's dead as far as (most) of the characters in the films know.
Comment: Worth pointing out as well that Vision makes a point of stating he's "burned him out of the net" meaning Ultron exists only in the robots at that point.


how to make a distort effect?

Question: My English is pretty basic, please don't mind. Wondering how to make the liquify wave and distort color effect in Photoshop? I'd tried using distort>shear/wave/zigzag, but still can't make it similar like the photo below.
Comment: Nothing is going to get you close to that in one step. There's no "magic filter" to pull off every possible visual alteration out there. It's going to take a *process* which you'll have to determine. My *guess* would be that image is a result of *physical* warping  to the photo negative during processing (someone folded/rolled a negative and it curled and distorted) and was *not* made digitally in its original form.
Comment: The tool to use is "filter->distort->displace..."
Comment: @Scott: as the zoom shows, the printing dots are also distorted, so it would be photo > printed image > photo > distort negative. (It would explain where the color fringes come from – the original b&w would not be able to cause that.) I find myself wonder what the original did look like, though. A simple passport mug shot?
Answer: It looks a bit like one of those images taken using the Slit Scan Camera Lite app available for Android, there's probably an iOS version too.  You can move the camera white it scans. Here I simply pointed it at an image on a monitor.

As for the colour changes/fringing - you could use Photoshop's liquify filter on some of the RGB channels individually.

The original image is here
Perhaps you could get better results using an actual scanner, and move the copy while it scans.

how to make a distort effect?


the phrase "to love to complain" is very common - is there one word that means this?

Question: For example, schadenfreude is the pleasure derived by someone from another person's misfortune.. I'm sure that someone's love of the act of complaining is encapsulated in one word, but I don't know what that word is!
Comment: @Lily - Do you care about the part of speech?  Could you give us a sentence with a blank where the desired word will go?
Comment: Curmudgeon comes to mind: http://www.merriam-webster.com/dictionary/curmudgeon
Comment: @FatherLuke I like that word, but it often has the connotation of "old age".
Comment: Hmm if we ignore the "love" requirement there are tons of words.  Critic, whiner, bellyacher.  Don't yet see any answers that deal with this behavior resulting from any love rather than say depression.  But maybe I'm just a naysayer. =)
Comment: Not particularly? It just needs to encompass BOTH parts of the meaning. So, it could be she is a "person who loves to complain" or "the love of complaining" is a common phenomenon.
Answer: Malcontent
http://dictionary.reference.com/browse/malcontent

malcontent
adjective

not satisfied or content with currently prevailing conditions or circumstances.

noun

a malcontent person, especially one who is chronically discontented or dissatisfied.
Comment: This refers to the emotion that a person experiences, not necessarily whether they are vocal about it (by complaining), and definitely not whether they _love_ to be vocal about it.
Answer: I doubt that there is a verb with such a specific meaning; as you cite 'schadenfreude', I assume other parts of speech are fair game.
A word that is perhaps a hypernym of what you request is cantankerous.
From AHDEL:

cantankerous  (adj)
Ill-tempered and quarrelsome; disagreeable

Synonyms for cross-grained {ODO} include awkward, difficult, uncooperative, perverse, contrary,  disobliging, unaccommodating, unreasonable, recalcitrant and refractory.
Agent nouns that are perhaps closer are carper, castigator, caviler (or caviller), censurer, criticizer, disparager, faultfinder, hypercritic, knocker, niggler, nitpicker (again ODO).
Answer: "Hater" comes to mind:

a person who thrives on showing hate toward, criticizing, or belittling other people or things, usually unfairly. - Dictionary.com
Answer: These may not be perfect fits with the "deriving pleasure" sentiment, but perhaps they might help:
Querulous

Full of complaints; complaining.
http://dictionary.reference.com/browse/querulous

Caviler

To raise irritating and trivial objections; find fault with unnecessarily
http://dictionary.reference.com/browse/cavil

Egocentric

Having or regarding the self or the individual as the center of all things.
Having little or no regard for interests, beliefs, or attitudes other than one's own; self-centered.

http://dictionary.reference.com/browse/egocentric
Comment: thanks, but not so much? I'm kind of trying to come up with the word that shows the tendency of humanity to complain about things FOR the sake of complaining, rather than changing their situation? As in, one might have 5 assignments due but instead of doing them they'll sit around complaining while other commiserate - and then when they don't have assignments they'll complain about that, because the ACT of complaining brings them satisfaction. I was joping there's a word for that :P
Comment: Unfortunately, I do know all these words :) I'm looking for one with that precise meaning, not somene who just complains a lot or is generally grumpy. Thanks anyhow!
Comment: @Lily, how about [argumentative](http://dictionary.reference.com/browse/argumentative)?  "Fond of or given to argument and dispute; disputatious; contentious."
But the way I understand what you're going for is something like the stereotypical "prissy bitch" popular high school girl that's mean to everyone just to get a rise out of them and laugh about it with her friends.  "Kvetching" is along those lines, perhaps, but I think it's closer to "bitching" and doesn't necessarily imply enjoyment is garnered from the whining.  Great question. Interested to see what you come up with.
Comment: @Lily You just said it: *commiseration*. The *human condition* is inescapable. A psychologist would probably give you a better understanding of *why*. Or perhaps a German could give you a better word: *schadenfreude* is on loan. There's a perfectly good idiom for this: *Misery loves company.*
Answer: How about "professional complainer"? Clearly it would have nothing to do with  a profession, but something that gives so much pleasure that it could become - for the unfortunate subject - as involving and time consuming as a normal occupation: his specialization, his profession.


How to work out given two coordinates should I use a vertical/horizontal/diagonal line to connect them

Question: I'm developing an android game and have essentially a grid. The user can drag a line between two points however the line will only ever be vertical, horizontal or diagonal (y=x). So I need to work out given two points which type of line is the best match.
Comment: Well if two points have the same x use vertical, same y use horizontal, different x and y use diagonal, right?
Comment: I don't think that will work because even if the x is diff it still might be closer to the vertical point than the diagonal so it should use vertical.
Comment: I think I understand more of what you're going for. For vertical you could compare the horizontal distance from the mouse pointer to the vertical line. Compare that distance to the horizontal distance to the y=x diagonal line for the current mouse y position. Then just pick which ever distance is smaller. For horizontal just do the same thing except compare the vertical distance.
Answer: Using vector calculations, you can calculate the angle between the two points, relative to an axis and then based on that angle, choose on how to draw the line.
If you have 2 vectors A and B, you subtract A from B, to get the vector that lies inbetween.
You then normalize the result and compare it with a given axis, e.g. y-axis = (0,1).
To get the angle between those two, you can use the acos of the dot product of both vectors.
The resulting formula would then be, for an input vector A and B, and the axis C:
angle = acos(dot(normalize(B - A), C))

If you are not familiar with vectors, these are the step-by-step calculations:
AB = B - A = (B.x - A.x | B.y - A.y)

#divide AB by its length, to get a vector of length 1
ABn = normalize(AB) = AB / square root of(AB.x² + AB.y²)
d = dot(ABn, C) = ABn.x * C.x + ABn.y * C.y
angle = acos(d)

The angle will always be between 0° and 180°, no matter on which side of the compared axis it lies.
If you compared your vector with the y-axis, you can simply check if

angle < 30°? -> vertical
angle < 60°? -> diagonal
angle < 120°? -> horizontal
angle < 150°? -> diagonal
otherwise (between 150-180°) -> vertical
Answer: I'm not sure I understood your question, but from what I got, you want the best representation for such line. A simple line containing both points would be the best.
If you want to test if something is inside the line, you want something similar:
Think of it in terms of a line that passes between the two.
It will have a initial point (your first point) and a direction. This direction, once multiplied by a given scalar t, will give you your p1.
Any other point you want to test will be given by that t. If you can't find a valid t, it's not in the line.
If t is negative, then you got something that lies on the infinite line, but not on the p0-p1 segment. If you got a t value bigger than the t that gives you your p1, than such point also lies out of the p0-p1 segment.
Hope it helps


Powering pulsed Ion Thruster

Question: The thrust of an Ion Thruster is directly proportional to the Input power. I've done some experimenting with DIY versions, and I was wondering: Since Power is simply Energy/Time, if I shot incredibly short pulses (microseconds) by means of let's say a Marx Generator through it, would that momentarily produce a high amount of thrust, or are there issues that would prevent that? I imagine it works similar to how a cannonball does more damage as a bullet at the same speed, but if the bullet is faster both can carry the same amount of kinetic energy.
Comment: "The thrust of an Ion Thruster is directly proportional to the Input power." No it's not. Much of the power just goes in to the mechanism necessary to ionize the gas and run the power supplies.
Comment: Even for the work done by acceleration this is not true at all. Thrust will be proportional to velocity, in fact proportional to the square root of the acceleration voltage times the current whereas the power used for acceleration is proportional to acceleration voltage times the current.
Answer: If you use 100 times the electric power for 1/100 of time periodically, you win nothing.
You get 100 times the thrust for 1/100 of time, mean thrust per time does not change.
You can't fool energy conservation, each try is in vain.

Powering pulsed Ion Thruster


How can I get to the Share menu without taking a screenshot?

Question: I have my Share button set to take shots immediately when I press the button (I have 280 shots of Second Son, I couldn't possibly use the press and hold style), but I've found every time I try and access the Share menu by holding the button it also takes a screenshot. Useful in a way, but sometimes I want to upload multiple screenshots from the past and I end up taking multiple useless screenshots of nothing trying to do this. For now I'm just screenshotting the PS4 home screen (so the shots go to a separate folder) but I'd really love some way to get directly to the share menu without a shot taken.
Answer: If you're using the screenshot config for the Share button, then a long press will take you to the Share menu.
I use this same config and sometimes mine will take an extra screenshot or two when trying to get in there.
I'm not sure if it's just some jitter on the button itself, or if the firmware is flaky when it comes to interpreting the Share button press, or whatever else could be wrong with it, but the behaviour you describe lines up with my own experience.


How do you do a kick serve?

Question: I typically do a hard flat first serve and then a slice second serve, but I'm curious to know the fundamentals behind adding "kick" to a serve for higher bounce.
Comment: How hard do you serve (MPH/KPH)?
Answer: The following is a rough, elementary answer. It disregards subtleties such as pronation which are relevant to high level play.
The fundamental mechanic behind a tennis serve is that of throwing a ball. In a basic flat serve, your motion is that of throwing a ball forward. In a kick serve, the motion (for a right-handed player) is of throwing a ball to the right. This is usually enough to force the racquet to hit the ball upwards, generating the desired spin.
Answer: I never was able to do it until I heard someone say "Hit the ball up". Once I imagined hitting up on the ball, ever so slightly, I started to get them in consistently, and by the end of the night I hit one over my parter's head!
Once you focus on something so simple as that, all the other pieces fall into place, i.e. brushing the ball, 7 o'clock-to-1 o'clock motion, and where to end your follow-through.
Apparently Naomi Osaka's coach uses an interesting drill to drive this point home:

How do you do a kick serve?


What kinds of charges/fees are there for NRI Home Loan from SBI?

Question: I have questions regarding Home Loan that I am taking from SBI.
When we(my spouse and I) initially went to the bank, the SBI, the NRI Branch manager told us about all the procedures for an NRI Home Loan. At that time the manager told us that there would not be any charges except for property search and valuation which were Rs 4000/- and Rs 1720/- respectively.
When I went to the bank the following week they gave me a paper which said I would have to take Home Loan Insurance and told me I had to sign that paper, which I did.
After a few days, we had signed all required papers and given them all to the bank. After submitting all the documents for loan sanctioning, the bank has now charged us more money which they had never told us earlier in spite of us asking them again and again about any hidden or required charges.
The Loan amount I have requested is Rs 98 Lakhs.
The breakdown of charges is as follows:

Advocate Fee- Rs 3000/-
Advocate Fee- Rs 4000/-
Values Fee-   Rs 1720/-
Search Of Property Fee - Rs 3000/-
Customer Loan Agreement Chrages Rs 19,800/-
Franking Charges for Agreement Rs 665/-

The charges total of Rs 32,185 which is 4 times more that what bank initially told us.
Are all these charges required by SBI?
Are all these charges imposed by other banks too?
Is home loan insurance mandatory? If not then what are policies of other private banks like ICICI or HDFC or Axis?
Any links or information from RBI that explains the home loan procedure will be much appreciated.
Answer: Generally the fees are anywhere between 0.5 and 2%.
Different banks have different fees. Generally these days competition ensures that the fees are nil.
It is disappointing that you were misled. File a written/email complaint. Generally the response to such things is good.
Home loan insurance is not mandatory by RBI. Quite a few banks ask for it as it's their policy. In the case of SBI it's more about cross selling their products.


AI natural voice generator

Question: I want to create a solution, which clones my voice. I tried my commercial solutions or implementation of Tacotron. Unfortunately, results not sound natural, generated voice sounds like a robot. Anybody could recommend good alternative?
Comment: hi @fuwiak I posted an answer. Hope it can help you and have a nice day!
Answer: The reason for robot like speech may be because tacotron uses griffin lim for vocoder, which cannot reproduce sound with perfection, often introducing robot like sound artifects.

A vocoder is a network that transforms a transform a spectrogram image back to speech waveform. Tacotron and many other speech generation neural network uses CNN to generate spectrogram instead of raw waveforms as output. Spectrogram is a lossy representation of raw audio waveform, so a perfect reconstruction of audio waveform is not possible. Griffin-Lim is a vocoder that uses algorithmic way to transform spectrogram to audio waveform, but often introduces a robot-like quality to generated waveforms. A neural network based vocoder can solve the problem. The wavenet vocoder is often used in speech generation as it can transform the spectrogram to audio with little artifects. Many new speech generation models use the wavenet vocoder as the deafult vocoder of the generation model. For a public implementation, this is a good github repository: https://github.com/r9y9/wavenet_vocoder
You can also use the newer tacotron 2 which uses the wavenet vocoder as the default vocoder. You can check it out here: https://github.com/Rayhane-mamah/Tacotron-2
Comment: In Tacotron-2, do you for each character in the input-text, how many frames of spectogram are generated during synthesis (inference)? The original paper at https://github.com/Rayhane-mamah/Tacotron-2 refers to sampling the "training dataset" at 1 frame per 12.5ms, which is different than number of frames per second.
Comment: Also, how does it associate spectogram frames with a  portion of the input text (e.g. an input character) during training phase, and what is number of frames per character during training? It must need to do that in order to learn using seq-2seq encoder/decoder system.

AI natural voice generator