How do I get palm rejection on my Dell Inspiron laptop?

Question: I just installed Ubuntu for the first time and I have no experience with Linux. One of the first things I noticed is that it appears the palm rejection for my laptop is gone. I have been googling this for an hour and tried a variety of different step-by-step guides, but for whatever reason I cannot seem to figure this out. I'm hoping someone can help me with my specific case. I would love to take the time to learn Linux, but I feel like I just need to get this out of the way first so I can type again without my hands at an incredibly unergonomic angle. I'm running 16.04 on a Dell Inspiron laptop. Thanks in advance.
Comment: @Alban is correct, it's a Windows vs. Linux drivers issue, but if you like, you should be able to disable "Tap to click" in the touchpad settings. This might be inconvenient unless you have a clickpad, like on many of the newer Inspiron laptops.
Answer: It's an old question, but seems to be unanswered so I'll throw in my two cents:
I'm running an Asus Q501D with 16.04, and I found that following this guide solved the issue.
The essence of it is modifying your xinput touchpad, which you find by running xinput list in the terminal and locating your touchpad device, whatever it be named, and its id in the output.
Then you modify the parameters using xinput set-prop [id] [prop] [setting] to enable palm rejection and change the dimensions of the palm region.  You can see all of your touchpad's props in the output xinput list-props [touchpad device id].
The relevant props were "Synaptics Palm Detection" and "Synaptics Palm Dimensions".  You'll want "Synaptics Palm Detection" 1 and "Synaptics Palm Dimensions" #, # to be something that actually rejects your palm (5, 5 worked for me and the author of the article).
Then it's just a matter of adding those prop-setting commands to your Startup Applications so that they run when you reboot (and thus preserve your settings).
Again, the linked guide has a few more details and screenshots, so definitely look there if I've botched up the explanation.  As a sidenote: The guide is written for 14.04, though, so maybe isn't compatible with all laptop makes depending on drivers?  Users in the comment section of the guide seem to have mixed results, but could just be user error, worked just fine for my machine.  Hope this helps!


SSB In Electroweak Theory

Question: I know that when vacuum state does not remain invariant under generators of lagrangian group symmetry, we have SSB in our theory:
$$
U_{a} | 0 \rangle = |0\rangle \Rightarrow  T_{a} | 0\rangle = 0 \qquad U_{a} \in SU(2) \times U(1)
$$
in A Pedagogical Review of Electroweak Symmetry Breaking Scan by Gautam Bhattacharyya, I found that we can show SSB in electroweak theory by acting generators on scalar field vacuum expectation value (scalar vev) :
$$
T_{a}\langle0|\phi|0\rangle
$$
the problem is I can not figure out what relation between these two can be according to QM
$$
T_{a} \langle 0|\phi|0\rangle \neq 0, \quad T_{a}|0\rangle \neq 0
$$
Answer: You need to think carefully about what space your quantities act on. $\phi$ is a quantum field (operator) acting on Hilbert space. However, by itself, $T^a$ is just an element of a Lie algebra in some representation. It acts on the appropriate representation space, not on Hilbert space.
Therefore, the notation $T^a \lvert 0 \rangle$ is sloppy. If you go back to Noether's theorem and see how the symmetry generators are defined, the symmetry generator $Q^a$, as an operator on Hilbert space, is actually given by
$$
Q^a = \int d^3 \; \dot{\phi}^\dagger_i(x) T^a_{ij} \phi_j(x) + \mathrm{h.c.}
$$
for a multi-component complex field $\phi_i(x)$ and $T^a_{ij}$ in the appropriate matrix representation. This corresponds to the infinitesimal symmetry transformation
$$
\phi_i(x) \to \phi_i(x) + i \epsilon T^a_{ij} \phi_j(x), \qquad \epsilon \ll 1.
$$
(I have assumed here a set of quite simple Lagrangians with kinetic term $\partial_t \phi^\dagger \partial_t \phi$, so that the canonical momentum for $\phi$ is $\dot{\phi}^\dagger = \partial_t \phi^\dagger$, but that is not necessary for this answer.)

SSB In Electroweak Theory


Is it a touchdown if a receiver flips over the end line and lands out of bounds?

Question: In the Bengals-Ravens game on 2023-11-16, the Ravens second touchdown was scored when a a receiver ran down field, flipped before the endzone and landed with his left foot out of bounds. Was the ruling of a touchdown correct, and if so why?
Comment: There's no need to the answer into the question - instead please accept (the check mark to the left) of the answer you find most useful.
Comment: Does this answer your question? [How can a touchdown catch be made when the receiver lands outside the End Zone?](https://sports.stackexchange.com/questions/17087/how-can-a-touchdown-catch-be-made-when-the-receiver-lands-outside-the-end-zone) - while it's not _quite_ the same scenario, it's the same rule (2.1.2).
Answer: https://x.com/Ravens/status/1725340444907782170?s=20
The rule states that the player needs to have possession of the ball and that the ball be inside/over (in the air) the zone. If the player jumps over an opponent, or a line, but puts the ball (think: one handed) over the zone, even when falling or being pushed outside, he had possession of the ball in the zone, so it's a clear TD.
From NFL - scoring plays:

SECTION 2 - TOUCHDOWN
ARTICLE 1. TOUCHDOWN PLAYS
A touchdown is scored when:

the ball is on, above, or behind the plane of the opponents' goal line (extended) and is in possession of a runner who has advanced from the field of play into the end zone
a ball in possession of an airborne runner is on, above, or behind the plane of the goal line, and some part of the ball passed over or inside the pylon
a ball in player possession touches the pylon, provided that, after contact by an opponent, no part of the player's body, except his hands or feet, struck the ground before the ball touched the pylon
any player who is legally inbounds catches or recovers a loose ball (3-2-4) that is on, above, or behind the opponent's goal line
the Referee awards a touchdown to a team that has been denied one by a palpably unfair act
Comment: It's interesting that in Rugby you need to touch the ball down to the ground but it's not called a touchdown whereas in football it's called a touchdown but you don't actually need to touch the ball to the ground.


Verifying that a TLS server supports the PSK-Modes Extension?

Question: I am trying to verify if a TLS Server is configured according to the guidelines specified in NIST SP 800-52.
One rule stated is the following:

TLS servers that support TLS 1.3 and the Pre-Shared Key extension shall support the Pre-Shared Key Exchange Modes extension.

How should I go about verifying if a server behaves this way while only interacting with the server from the outside?
My idea was performing two handshakes with different Key Exchange Modes set in the extension. But I am not quite sure how I would decide based on the responses I get from the server.
Answer: Support for the psk_key_exchange_modes extension is mandatory if the server supports pre-shared keys. So this is not a matter of server configuration, it's just a matter of having a compliant implementation of the TLS protocol. It isn't something you need to test for to assess compliance to NIST guidelines.
If you want to test the TLS implementation, try to establish a TLS session with a pre-shared key. If it works, then the server did accept an incoming psk_key_exchange_modes extension. If you want to test the implementation further, do what you'd do for testing anything: send a variety of good and bad inputs (valid extension, invalid extension, missing extension with a pre-shared key, etc.), and verify that the server responds as expected (by establishing a session with the requested parameters, or by closing the connection, depending on whether it's a good or a bad test case).


RAID 10 Vs RAID 5

Question: I noticed that RAID 5 has been used for a lot of critical application such as SQL server machine.
However RAID 10 seems to be a lot more robust. But not much people using it.  Any reason why or when should we consider RAID 10 or never?
Comment: possible duplicate of [What are the different widely used RAID levels and when should I consider them?](http://serverfault.com/questions/339128/what-are-the-different-widely-used-raid-levels-and-when-should-i-consider-them)
Comment: What evidence do you have that supports the idea that RAID10 is not commonly being used?
Answer: This question will depend greatly on your hardware, server workload and storage capacity.
For example, Raid 10 can have considerable performance increases over Raid 5 (especially on random or small writes), but storage capacity is cut in half. The performance differences may not even be noticeable depending on the load, so the Raid 5 with the extra space may be more appealing.
Let's assume we have 12 1TB hard drives. In a raid 5 we would get:
* Usable Space: 10TB (using base-2, what your operating system would see)
* Fault Tolerance: 1 drive can fail
* Read Speed: 11x
* Write Speed: < 1x
Pro's:
* The best storage efficiency
* High sequential read performance
Downsides to Raid 5:
* Rebuilding a bad drive can take very long time and will cause a medium performance decrease during the rebuilding process. You will have zero fault tolerance during this process.
* Overall performance degrades as the % of writes increase. This is due to I/O balancing.
Now take 12, 1TB hard drives in a raid 10:
* Useable space: 5.4TB
* Read speed: 12x (theoretical)
* Write Speed: 6x (theoretical)
* Fault Tolerance: can lose 1 drive in every raid 1 array, 6 in this example.  But you cannot lose 2 drives in a single raid 1
Pros:
* High fault tolerance (as long as two drives in a mirror do not fail)
* Fast reads, writes, and random/small writes (important in databases)
* Fast rebuild times in case of disk error
Cons:
* 50% of your disk space is gone, and this is usually the deal breaker for most wihtout large budgets.
* Scalability can get expensive
For me, if I am on the fence between a 10 or 5 then I usually go with a RAID 50. This is a good balance between the two (cards that support Raid 50 can get expensive though).
Raid 50
* Useable space: 9TB
* Read Speed: 10x
* Write Speed:< 2x
* Fault tolerance: 2 drives
* Faster than raid 5 write speeds
* Good storage efficiency
* Fast read speeds
* Less of penalty to rebuild bad disk
* Retain fault tolerance if one disk fails
Again, a lot of variables will go into performance on these things: quality of the raid card, speed of the drives, number of drives in your pool, disk/strip alignment in databases, etc.
Answer: Wikipedia say :
The choice between RAID 10 and RAID 5 for the purpose of housing a relational database depends upon a number of factors (spindle availability, cost, business risk, etc.) but, from a performance standpoint, it depends mostly on the type of I/O expected for a particular database application.RAID 10 is often chosen because it offers a slight speed improvement over RAID 5 on sustained reads and sustained randomized writes.
For details visit :
http://en.wikipedia.org/wiki/RAID#RAID_10_versus_RAID_5_in_Relational_Databases
http://www.thegeekstuff.com/2010/08/raid-levels-tutorial/
Answer: As mentioned before, most go straight for RAID5 due to cost issues. I use RAID10 for my small setups at work due to them being easier to recover if something goes wrong. If more than one disk goes, there is nearly 0 chance of recovery. With RAID10, for files at least, you have the ability to recover partial bits when things go wrong.
+1 for the BAARF above.
Answer: For RDBMS's, some good arguments at: http://www.baarf.com/
RAID 5 is used a lot due to cost issues, and many people use it as a "default" without thinking further.

RAID 10 Vs RAID 5


Get and show images from Facebook in iOS app

Question: I'm developing a iOS app for iPad. I've implemented Instagram API so I can get and use the photos from the user. Can I do the same but with Facebook? Is there any way to access to users' pictures?
Thanks
Answer: The Graph API is where you want to start to see what data you're looking for. For user photos, check out:
Albums user has created -
https://developers.facebook.com/docs/reference/api/user/
Info about a photo -
https://developers.facebook.com/docs/reference/api/photo/
I recommend trying different queries using the Graph API explorer:
https://developers.facebook.com/tools/explorer
First make sure you ask for user_photos permission
Entering me/albums in the query gives you a list of albums for the logged in user. Click on an album's ID in the results to see the info for that album. Enter /photos to see photos for that album.
Once you know what you want you can take a look at the iOS SDKs that are built on top of the Graph API and other APIs to authenticate and for what you're interested in, to grab photos.
For iOS SDK info on making requests, see:
https://developers.facebook.com/docs/reference/ios/3.1/class/FBRequestConnection#startWithGraphPath%3AcompletionHandler%3A
So if you want to see say the photos for one album, given an album_id, you would use request code like:
[FBRequestConnection startWithGraphPath:@"<album_id>/photos"
    completionHandler:^(FBRequestConnection *connection, id result, NSError *error) {
       if (!error) {
           NSLog("Results: %@", result);
       }
    }
];

Make sure you've asked for user_photos permissions first.
Answer: - (IBAction)btnFBTap:(id)sender {
    [FBSDKProfile enableUpdatesOnAccessTokenChange:YES];
    if ([FBSDKAccessToken currentAccessToken]) {
        [self FBLogin];
    } else  {

        FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
        [login
         logInWithReadPermissions: @[@"public_profile", @"user_photos"]
         fromViewController:self
         handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {
             if (error) {
                 // Process error
             } else if (result.isCancelled) {
                 // Handle cancellations
             } else {
                 [self FBLogin];
                 // If you ask for multiple permissions at once, you
                 // should check if specific permissions missing
             }
         }];
    }
}

- (void)FBLogin {

    [[[FBSDKGraphRequest alloc] initWithGraphPath:@"me"
                                       parameters:@{@"fields":@"id"}]
     startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {
         [[MDManager sharedInstance].loadingView hide];
         if (!error) {
             NSLog(@"fetched user:%@", result);

             // For more complex open graph stories, use `FBSDKShareAPI`
             // with `FBSDKShareOpenGraphContent`
             /* make the API call */
             FBSDKGraphRequest *request = [[FBSDKGraphRequest alloc]
                                           initWithGraphPath:[NSString stringWithFormat:@"/%@/photos", result[@"id"]]
                                           parameters:@{@"type":@"uploaded",
                                                        @"fields":@"link,height,width"}
                                           HTTPMethod:@"GET"];
             [request startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection,
                                                   id result,
                                                   NSError *error) {
                 NSLog(@"%@",result); // Return uploaded photos

             }];
         }
     }];
}

Comment: yes i update my app is not live yet the response i get is Optional({
    data =     (
    );
})
Comment: I think this problem connected to permissions.


Can I create a signature in the contract?

Question: I can use the function ecrecover to verify a signature in the contract, but I want to know how to create a
signature in the contract. What should I do?
Answer: Short answer
You cannot.
Better answer
You shouldn't want to.
There is a two-fold engineering dilemma.

The computationally-heavy work of creating a signature isn't well-suited to a platform where cost is proportional to work. There are workarounds, but ...

Anything a contract can do is replicable by everyone else. For example, the whole idea of a signature is that it proves knowledge of a secret only the signer should know - the private key. For a contract to perform this process, the contract would have to know the secret. If that is the case, then everyone knows the secret which renders a signature meaningless.

They don't need to
In most cases, what you want is to show that an action came from the contract. This is handled at a protocol level without the need for the contract to sign anything.
I might suggest reframing the question in terms of what needs to be proven because it's probably doable. The solution will not include the contract signing in the way that externally-owned accounts do it.
Hope it helps.


GPIO behaviour on booting RPi

Question: I have a question regarding the GPIO status during the boot process.
As a bit of background, I'm currently building an automated sprinkler setup using a raspberry pi and an 8-relay board.
The board wiring is pretty simple, you supply and input with ground, and the relay activates and is indicated with an LED.
Pretty straightforward to wire up.
However, I noticed the GPIO pins are not exactly 0 when booting the device, they are not 1 either, because I can see the relay LED's blink faintly while booting the pi.
Once the device has booted, it works as expected and when a pin is pulled to ground the LED lights up brightly and the relay clicks.
I'm not sure what is going on here, I have tested with another pi, but the result is the same.
The relay board is powered externally, all the pi has to do is give pulse to the board.
Anybody any ideas? Is there some settings I can adjust in order to keep pins where they are while booting?
I realise this is not a huge problem because the boot time is not too long, but still.
Comment: Welcome. *"I noticed the GPIO pins are not exactly 0 when booting the device, they are not 1 either..."* Yep,  from power on until they are configured differently by software, the default state for most of them is as an input, which means unless they are pulled sufficiently up or down they will be in a high-z "floating" state: https://en.wikipedia.org/wiki/High_impedance#Digital_electronics Pretty sure the only remedy to this, if it is a significant problem,  is via external circuitry.
Comment: oh wow, I thought this was a mistake on my part, but this is just by design then...
So I would need to turn on 3.3 V manualy in software for the relay board to turn on for example?
Thank you for explaining this to me!
Comment: No, that's just the GPIO pins.  The power and grounds aren't GPIOs, they only have one state and that cannot be changed.  The choice of a floating input default state is presumably because it is the least dangerous (there will be no damage if they are connected to a ground or <=3.3V current source, whereas there could be with an output pin).  But depending on what you have connected, there isn't really any perfectly safe choice.  So if you do connect things, you need to be  aware of this and take appropriate pre-cautions if necessary.
Comment: Yeah, I managed to explain it poorly again...
What I really mean is: if I don't want to risc a relay firing during boot because of floaty GPIO, I could unpower the relay board via a transistor of some sort until the program runs. And the instant the program runs, trigger the transistor that powers the relay board? I hope this makes more sense?
It would still be powered from the 3.3V rpi pin, but separated with a transistor.
Comment: You will need to think about what kind of transistor to use keeping in mind the control input on that will potentially be floating at boot too -- but that can be remedied via an internal (and controllable) pull-up/down, as per Milliway's post most pins have a default that way.  In theory you might be able to do that with the relay control directly (ie., no need for the transistor).  There's a lot of similar questions here, maybe something worth gleaning along those lines:  https://raspberrypi.stackexchange.com/search?q=relay+GPIO+boot+is%3Aquestion
Answer: The Pi (in common with most computers) starts with all pins as input.
The SoC sets pins 0-7 with pullup all others with pull down. (GPIO 2,3 have physical pullup resistors.) This is well documented.
If you want to override this you can use physical pull resistors which will override the weak default 50k pull.
You can set the state of pins in config.sys although there is a small delay before this applies.
Comment: Thank you so much for explaining this!

GPIO behaviour on booting RPi


'New' Button is not visible for system admin for account object list view page

Question: New button is not visible for system Admin profile in salesforce lightning but visible in classic version, on list view page.
Comment: As suggested in https://trailblazers.salesforce.com/answers?id=9063A000000peUrQAI  you might want to check if the "New' button is overridden by a Visualforce page which is not marked "Available for Lightning Experience, Lightning Communities, and the mobile app".
Answer: Try using below step
Setup > Object Manager > (Object) > Search Layouts >
List View > Edit
Check the checkbox true for New [New]
and click Save
Reply if it does work.


Application Error on heroku

Question: I'm follow an online railstutorial.
I'm a newbie, and now I finished just my second app.
It works ok on a local machine, but I have a problem with heroku.
I pushing my app successfully, and then I done heroku rake db:migrate
But I see this error on my page

An error occurred in the application and your page could not be
  served. Please try again in a few moments. If you are the application
  owner, check your logs for details

And I see this warning in command line:

rake aborted! Please install the postgresql adapter: gem install
  activerecord-postgresql-adap ter (pg is not part of the bundle. Add
  it to Gemfile.)

I google this error and found that I need add this strings to my gemfile:

gem 'sqlite3', :group => :development
  gem 'pg', :group => :production

Done it, and retried, but nothing changed, and I still have this in my command line

Please install the postgresql adapter: gem install
  activerecord-postgresql-adap ter (pg is not part of the bundle. Add
  it to Gemfile.)

I can't understand it, cause I defenitely had pg gem, and I can see his installation on my local machine
Using thor (0.14.6)
Using railties (3.2.1)
Using coffee-rails (3.2.2)
Using jquery-rails (2.0.2)
Using pg (0.13.2)
Using rails (3.2.1)
Using sass (3.1.16)
Using sass-rails (3.2.5)
Using sqlite3 (1.3.6)
Using uglifier (1.2.4)

but I can't see the same, when bundle installing on heroku server
 Installing thor (0.14.6)
  Installing railties (3.2.1)
  Installing coffee-rails (3.2.2)
  Installing jquery-rails (2.0.2)
  Using bundler (1.0.7)
  Installing rails (3.2.1)
  Installing sass (3.1.16)
  Installing sass-rails (3.2.5)
  Installing uglifier (1.2.4)

How can I solve it? Really have no idea. Please help me.
btw, sorry for my english, I'm from russia)
update:
yeah, i see that it runs bundle install --without development, but my gemfile now looks like:
group :production do
  gem 'pg'
end
group :development, :test do
   gem 'sqlite3-ruby', :require => 'sqlite3'
end

as you can see, 'pg' is definitely out of development group, but heroku didn't install it
Answer: Looks like you added the pg gem to the development group in your Gemfile - when Heroku deploys, it runs bundle install --without development, meaning that it'll not install gems in that group. Move the gem outside of the development group.
Answer: If you've updated your Gemfile make sure you commit it and the Gemfile.lock to git and then repush your application to Heroku.
Comment: sure I commit it, and repush only after that

Application Error on heroku


Why does the installer make an extended partition for swap by default?

Question: Every time I've done a clean default install of Ubuntu or a variant on an MBR type system, I end up with a system partition and a swap partition.  The installer always tucks the swap partition inside an extended partition.
Why?  It seems more straightforward to create two simple partitions.  But I am guessing that there is a good reason and I am showing my ignorance here.
Answer: Primary partition is only needed when you want to make it bootable. If you look up wikipedia there's a "full story" about that. Extended and logical partitions have some cons. But if you want a primary swap partition, you can partition it by yourself, it's not hard and you seem like you understand what are you talking about, so it shouldn't be a problem for you. There's a manual partitioning in most installers, or you can use GParted, fdisk, disked and others.
Hope this helps :)
Comment: Primary partition is not needed for booting. All major OSes nowadays can boot from logical partition without problem. Only ancient ones like XP or 9x suffer from this
Answer: There are many ways to create partitions for Ubuntu installations.
Default is primary /, and swap in a logical one.
It does not matter for linux which type of partition to boot from (logical or primary).
The reason why this layout has been chosen must be that it is not always possible to create 2 primary partitions, when system is installed in parallel with some other OS, like Windows.
There is a limit in MBR of 4 primary partitions.
I would choose in this case to create an extended and two logical for / and swap instead.
Anyway this is just a default layout, you can change it as you like.


I have a centos server and I am trying to monitor memory via snmp but didnot got the actual result

Question: I have a centos server and I am trying to monitor memory but didnot got the actual result. I have used Snmpwalk and used the oid of the used memory but it is returning me the value that is not matched to any parameter. The server is hosted inside esxi.
I have used the command:
snmpwalk -v2c -c test@123 10.10.0.120 .220.127.116.11.4.1.2021.4.6.0

this command should provide me used memory but i am getting the value of something else. The result I got is:
UCD-SNMP-MIB::memAvailReal.0 = INTEGER: 5315584 kB

            total        used        free      shared  buff/cache   available
Mem:          7.6Gi       1.5Gi       5.1Gi       113Mi       1.0Gi       5.7Gi
Swap:         5.0Gi          0B       5.0Gi

In the output the used is 1.5Gi but the output of snmpwalk is around 5.3Gi.
Is there any way i can get the oid of the free, used and available memory. Or is there any way we can list UCD-SNMP-MIB::memAvailReal.0 and its corresponding oid.
Comment: Run `free` _without_ `-h`.
Answer: Can you try to snmpwalk the entire tree 220.127.116.11.4.1.2021.4 ?
You will get a clear overview of the possible snmp return.
Check this link to have the description of the tree.


Can you encrypt data using BCRYPT?

Question: Somebody else posted a question about ghostmail (https://www.ghostmail.com/crypto) and whether it looks valid. One of the things that triggered alarm bells for me was the sentence "Account Password (This is sent and stored encrypted using BCRYPT)". Do they simply not know the difference between hashing and encryption, or is there actually a way to encrypt a password with BCRYPT?
Comment: The key part of bcrypt is that it's one-way. Encryption requires a two-way property. Hashing: one-way, Encryption: two-way
Comment: @Oasiscircle so is it safe to say that the companies claim is wrong?
Comment: They probably send it by encrypting with SSL/TLS and store it by hashing with bcrypt. I feel like they just left that off to make it shorter.
Comment: @Oasiscircle, technically you could run CTR with a standard hash function (or a PBKDF like bcrypt), it would just be incredibly slow.
Comment: @SEJPM How do you intend to decrypt a ciphertext constructed with a cryptographic hash function? CTR just converts a block cipher into a stream cipher.
Comment: @Oasiscircle http://crypto.stackexchange.com/a/3020/23623 How do you normally decrypt in CTR mode? With your encrypt function!
Answer: In that case, it is probably the password hashing function bcrypt, described by someone who does not make the difference between "hashing" and "encryption". Bad terminology, good function.
It must be said that there is an encryption tool called bcrypt as well, and which is known to do things very poorly, as far as encryption tools go. This is occasionally the source of great confusion.
Comment: So they're either using the right tool or the wrong one. Glad that's settled. ;)
Comment: It could be written to appeal to people who don't know what cryptographic hashing is, and so deliberately using the term encryption in a very loose sense.
Answer: I am replying on behalf of GhostMail.
First of all we are sorry for the possible confusion.
The misunderstanding related to encryption vs hashing using the BCRYPT algorithm has been corrected on our website.
As pointed out by Oasiscircle they are obviously two different things for different purposes.
BCRYPT is a key derivation function used to compute a cryptographic hash of a password to store in some database.
It is worth noting that in this case the "Account Password" itself is a cryptographic hash computed at the client side using PBKDF2 and SHA-256 as the hashing algorithm and which performs 5000 rounds of hashing.
This technique is also called key stretching.
If any further questions about our crypto design we will be happy to assist.
Comment: Hi, and welcome to secse! We're glad to have you here. It seems you even took the tour. :] Thanks for your input.
Comment: so, you send an account salt to client, perform a 5000 iteration client side hash, then client sends the hash over SSL to you, and you derive key using bcrypt, which is then used to authenticate the user?
Comment: The salt is inserted at the client side and is based on the username and the domain. The client then sends the hash computed by pbkdf2 over TLS and on the server side this hash is used to compute another hash with bcrypt, which is then stored and used to authenticate the user.

Can you encrypt data using BCRYPT?


Hotkeys in russian keyboard layout

Question: I saw many CLOSED topics about this, BUT none of proposed solutions working. When I switch to russian keyboard, shortcuts (ctrl+c, ctrl+v, ctrl+z, etc.) not working in most of applications. I have updated system 14.04. Propose the solution, but don't just close the thread saying that everything is working! Thanks in advance for any help, because I'm realy tired of this and start to think about other Linux distros.
Comment: Inkscape - ctrl+z, ctrl+shift+z, ctrl+c, ctrl+v, ctrl+o... (all shortcuts) not working; Lazarus - only ctrl+I working, others - not; VLC - all shortcuts not working... Is there any sense to continue?
Comment: Never mind, keep saying that everything works. Solved by replacing Ubuntu with another OS. Sad, but true.
Comment: Give please an example of application which does not do `CTRL`+`C`or `CTRL`+`V` with switched Russian input on.
Comment: I am having this problem too. Ctrl-c Ctrl-v hotkeys are not working for me when Russian keyboard layout is enabled
Answer: This worked for me
<code>sudo add-apt-repository ppa:attente/java-non-latin-shortcuts
sudo apt-get update
sudo apt-get dist-upgrade
restart unity-settings-daemon
</code>

Hotkeys in russian keyboard layout


flame temperature and pollutant

Question: When burning fossil fuel or wood, there would always be pollutant. But some technology claims that it could redece pollution by decreasing the burning temperature. Is that true? And can any one give me a source that detailed why it happen or not happen?
Answer: generally NOT true. Chemically speaking, higher temperature combustion of a fuel in oxygen tends to go more thoroughly to completion compared to lower temperature combustion.
However, higher temperature combustion tends to produce more oxides of nitrogen, which are considered pollutants.
Therefore, minimization of pollutants in the exhaust stream of a combustion process is a compromise between minimization of unburned or partially-combusted fuel and minimization of NOx creation.
Answer: Combustion of hydrocarbons in presence of air (mixture of Oxygen and Nitrogen) at high temperature (and pressure) will lead to the production of nitrous oxides, which are a group of pollutants. As you lower the combustion temperature by some means, even though the nitrous emissions would decrease, the fossil fuel combustion would tend to produce more unburned hydrocarbons, soot particles and carbon monoxide, which are another group of pollutants. Pollutants are produced as you move along both sides of temperature axis.
The claim of pollutant reduction by decreasing temperature must be seen in this context.

flame temperature and pollutant


If you made a minor error in publishing the experimental protocol of an experiment, what would happen?

Question: If you were to publish a paper but you made an error in publishing the experimental protocol or parameters, what would happen to the paper? Let's say in this instance that the results of the experiments wouldn't be significantly affected. How would that process work? Would there have to be a retraction? A correction?
Comment: Was the experiment actually carried out correctly? Is it just a matter of misstatements in the paper?
Comment: The experiment was carried out at slightly different parameters than what was written, as a result of input error. Doing them with the parameters that were written got similar results.
Comment: Did the experiment involve anything random? Sampling, for example?
Comment: The experimental parameter that was affected was wavelength at which excitation and emission were measured. In both cases, they were 5 nm off from what was reported (due to misremembering the correct wavelengths during setup), and doing them at the reported wavelengths didn't affect the outcome of the experiments much at all.
Comment: Life as we know it may come to an end. Or not…
Answer: In most such situations there is no need for a correction. If random elements of any kind are involved then the effect of randomness might overcome small changes in parameters. You might be able to analyze that from your data.
If the system is relatively smooth then, again, small changes in inputs result in small output changes.
There are systems, however in which none of that is true. In any chaotic system (weather, for example) small changes can result in large effects.
Another factor to consider, however, is what real world effects might arise from getting it wrong. In some medical systems, say, it is important to be absolutely precise as lives may depend on results.
So, make a judgement call. If small changes result in small effects AND if there are no adverse health/societal impacts for being slightly wrong, then it can probably just slide.
You can also present your case to the publisher of your work and let them decide if a correction needs to be made.
Comment: And please use a log book or similar careful logging practices during experiments and their setup rather than relying on memory.
Comment: I see. In this case, the mistaken changes to the parameters were so minor that it had no significant effect on the outcome of the experiment. The reason why the mistake went unnoticed was because the results from each configuration (the ones from the correct configuration and the ones from the incorrect configuration) were indistinguishable from one another such that no alarms were raised.


Has Hawking Radiation Ever Been Observed?

Question: I know Hawking Radiation has firm theoretical footing, but has a signal ever actually been observed? What observational research is being done to attempt to see this effect? Is it simply too tall an order (i.e. - too far away, too weak of a signal, etc..)?
Comment: As far as I know, the answer is no for the first to questions. But I'm uncertain about the last, I bet there's some ingenious technique stashed somewhere in the arXiv. I'll try to look for one when I have the time.
Comment: Perhaps, the answer in the following link be helpful for the physics enthusiasts:  https://astronomy.stackexchange.com/questions/43376/can-hawking-radiation-ever-be-detected-and-does-it-exist/43380#43380
Answer: According to this MIT Technology Review "First Observation of Hawking Radiation" and an associated article "Hawking radiation from ultrashort laser pulse filaments" where the authors have simulated Hawking radiation in the laboratory, using ultrashort laser pulse filaments.
So, in part answer to your question, yes Hawking Radiation is believed to have been observed, but in a laboratory environment.
According to "Observing Hawking radiation in Bose-Einstein condensates
via correlation measurements" (Fabbri, 2012), direct observation of the Hawking radiation is (in their word): hopeless.
However, once again simulations are possible:

Hawking effect, which depends only on kinematical properties of wave propagation
  in the presence of horizons, is present also in nongravitational contexts,
  for instance in stationary fluids undergoing supersonic flow.

From these articles, it would seem that direct observations of Hawking radiation is not feasible currently; however, we are able to produce analogues of the phenomena in the laboratory.


Subsonic 3 Linq Projection Issue

Question: OK I'm banging my head against a wall with this one ;-)
Given tables in my database called Address, Customer and CustomerType, I want to display combined summary information about the customer so I create a query to join these two tables and retrieve a specified result.
<code> var customers = (from c in tblCustomer.All()
                        join address in tblAddress.All() on c.Address equals address.AddressId
                        join type in tblCustomerType.All() on c.CustomerType equals type.CustomerTypeId
                        select new CustomerSummaryView
                                   {
                                       CustomerName = c.CustomerName,
                                       CustomerType = type.Description,
                                       Postcode = address.Postcode
                                   });

  return View(customers);
</code>
CustomerSummaryView is a simple POCO
<code>public class CustomerSummaryView
{
    public string Postcode { get; set; }
    public string CustomerType { get; set; }
    public string CustomerName { get; set; }
}
</code>
Now for some reason, this doesn't work, I get an IEnumerable list of CustomerSummaryView results, each record has a customer name and a postcode but the customer type field is always null.
I've recreated this problem several times with different database tables, and projected classes.
Anyone any ideas?
Answer: I can't repro this issue - here's a test I just tried:
<code>[Fact]
public void Joined_Projection_Should_Return_All_Values() {
    var qry = (from c in _db.Customers
                     join order in _db.Orders on c.CustomerID equals order.CustomerID
                     join details in _db.OrderDetails on order.OrderID equals details.OrderID
                     join products in _db.Products on details.ProductID equals products.ProductID
                     select new CustomerSummaryView
                     {
                         CustomerID = c.CustomerID,
                         OrderID = order.OrderID,
                         ProductName = products.ProductName
                     });

    Assert.True(qry.Count() > 0);

    foreach (var view in qry) {
        Assert.False(String.IsNullOrEmpty(view.ProductName));
        Assert.True(view.OrderID > 0);
        Assert.False(String.IsNullOrEmpty(view.CustomerID));
    }

}
</code>
This passed perfectly. I'm wondering if you're using a reserved word in there?
Comment: Hey Rob, I think your test passes because your mappings are exact matches. Jon is doing CustomerType = type.Description, and this happens to be the only property he is having problems with. I ran into something very similar http://stackoverflow.com/questions/1734146/subsonic-3-linq-projecting-anonymous-types-but-not-class-types
Answer: This post seems to be referring to a similar issue...
http://groups.google.com/group/subsonicproject/browse_thread/thread/2b569539b7f67a34?hl=en&pli=1
Answer: Yes, the reason Rob's example works is because his projection's property names match exactly, whereas John's original example has a difference between CustomerType and type.Description.
This shouldn't have been a problem, but it was - the Projection Mapper was looking for properties of the same name and wasn't mapping a value if it didn't find a match.  Therefore, your projection objects' properties would be default values for its type if there wasn't an exact name match.
The good news is, I got the latest source today and built a new Subsonic.Core.dll and the behavior is now fixed.
So John's code above should work as expected.
Answer: I just downloaded the latest build from 3/21/2010, which is about 2 months after the last poster on this thread, and the problem still exists in the packaged binary.  Bummer.
Here what I have to do:
<code>        var data =
            (from m in Metric.All()
             where m.ParentMetricId == parentId
             select new
                    {
                         m.MetricName,
                         m.MetricId,
                    })
                    .ToList();

        var treeData =
            from d in data
            select new TreeViewItem
                    {
                        Text = d.MetricName,
                        Value = d.MetricId.ToString(),
                        LoadOnDemand = true,
                        Enabled = true,
                    };

        return new JsonResult { Data = treeData };
</code>
If I try to do the projection directly from the Subsonic query, the Text property ends up with the ID, and the Value property ends up with the Name.  Very strange.

Subsonic 3 Linq Projection Issue


shepherd effect and continuity effect

Question: As far as I have understood a Shepherd tone is a combination of overtones of different octaves between them, for instance F0, 2F0, 4F0 and 8F0. Is this true?
I do not quite understand what the Shepherd EFFECT is.
Answer: Simply put, the Shepard effect is an auditory illusion where your brain is tricked into believing that a sound is continuously going up or down.
Wikipedia actually has a very good explanation of how an ascending Shepard tone is structured:

Overlapping notes that play at the same time are exactly one octave apart, and each scale fades in and fades out so that hearing the beginning or end of any given scale is impossible. As a conceptual example of an ascending Shepard scale, the first tone could be an almost inaudible C4 (middle C) and a loud C5 (an octave higher). The next would be a slightly louder C♯4 and a slightly quieter C♯5; the next would be a still louder D4 and a still quieter D5. The two frequencies would be equally loud at the middle of the octave (F♯4 and F♯5), and the eleventh tone would be a loud B4 and an almost inaudible B5 with the addition of an almost inaudible B3. The twelfth tone would then be the same as the first, and the cycle could continue indefinitely. (In other words, each tone consists of two sine waves with frequencies separated by octaves; the intensity of each is e.g. a raised cosine function of its separation in semitones from a peak frequency, which in the above example would be B4.)

shepherd effect and continuity effect


Cardano Node 1.35.4 problems

Question: I am running cardano node 1.35.4 on Windows 10 it syncs to 100% then gives me the following screen
Answer: If you are asking about Unsupported remote target address ... errors (ipv6), then I suspect that you start the node only specifying IPv4 address.  To get IPv6 address either:

do not specify ip addresses at all (then the node should discover which addresses the host machine supports); or
specify both IPv4 and IPv6

If you just specify one of them, the node will only bind to that address, and be able to use outbound connections using that IP version.  This allows us to support environments where IPv4 or IPv6 is not available.
Comment: Thanks for your help , I am currently not specifying any IP address
cardano-node run --topology "configuration\cardano\testnet-topology.json" --database-path "db" --socket-path "\\.\pipe\cardano-node-testnet" --port 3001 --config "configuration\cardano\testnet-config.json"

Cardano Node 1.35.4 problems


Reporting cyberstalking

Question: I have been under cyberstalking. But it is very difficult to prove the source rigorously given that the sender can fake the header information. Is it possible to report the stalking to the police?
Answer: You can report cyberstalking to police, but it is unlikely that they will do anything about it if they can't prove who did it easily in a definitive way without advanced IT resources. At a minimum, a police report will document with a third party that the problem existed in the event that the situation escalates later.
Most police departments are not equipped to do sophisticated investigations of Internet based crimes, and in general, police departments tend to put a low priority on crimes that don't involve physical harm or damage to property in the thousands of dollars. Even if the case is presented to them wrapped up in a bow and basically solved with solid proof in hand, it is hard to get their attention.
The FBI is better equipped to deal with cyber crime but also has higher thresholds of harm before they are willing to use their scarce resources to pursue a case.
Comment: Then what is the next step to stop stalking?
Comment: @user13043 Not a legal one.
Comment: Sometimes asking them to stop, giving them a definite idea that the communications/messages/etc. are not welcome will help.

Reporting cyberstalking


Possible to generate yearly archives?

Question: Are there any plugins that make it possible to have yearly archives in EE? I'm talking about something like the current archives-by-month (January, February, etc. with the ability to paginate), but listing all entries posted in a full calendar year. I'm looking at moving to a responsive design, and want the date-based archives in the top menu like they are now...but I would love the option to link to a paginated template that lists all entries in a given calendar year (all entries in 2011, all entries in 2012, all entries in 2013...and so forth.) That would really shorten the top nav a LOT.
Answer: Actually, Low Yearly Archives should work for you, in combination with the native channel:entries tag. If you don't use the {months}{/months} variable pair to output the months, but just use the years to link to something like /such/obsessive/distractions/2014, then you could simply use the year="" parameter to output entries for that year.
Comment: Just use `year="{segment_4}"` where the segment variable points to the year in the URI. Also add `dynamic="no"` to make sure EE shows you what you tell it to show.
Comment: I currently use the native channel:entries tag to display the entries on that template - so I'm partially there, I think. But when you say "use the year parameter to output entries for that year"...sorry, I'm not following. The tag+parameters I currently use on the distractions template is exp:channel:entries channel="spc-content" orderby="date" sort="desc" limit="10" show_future_entries="no" paginate="bottom" rdf="off" status="open|Featured" Would I need to create separate templates for each year, and add in the year parameter?
Answer: Maybe this is what you are looking for? http://devot-ee.com/add-ons/low-yearly-archives
Comment: I've downloaded that and tried it out. It generates your archives separated into years, but it just links to your existing monthly-archive templates. I currently have monthly archives at http://www.sparklecrackcentral.com/such/obsessive/distractions/2014/03 (for example) I want to have a template that can display all archives for a given year ie http://www.sparklecrackcentral.com/such/obsessive/distractions/2014 (but EE currently does not have this functionality.)
Answer: You could do that kind of archive using stash match and against parameters and pagination.
Have a look at the example here: https://gist.github.com/croxton/6219973
Answer: You can filter entries by using a year in the URL: mysite.com/archives/2012
{exp:channel:entries channel="my channel" year="{segment_2}"}
// show all entries from year in URL
{/exp:channel:entries}

Here's the documentation: http://ellislab.com/expressionengine/user-guide/add-ons/channel/channel_entries.html#id68

Possible to generate yearly archives?


Is there a way to overwrite defaul font for a specific app Android 5.0?

Question: An app I ran on Android system before Lollipop (LG G2 phone) where the system font worked inside the app, no longer affects the application (LG G3) in Lollipop. As far as I know, all settings are the same but the font will not affect the app any longer. Is there a way to set default font for inside of the app? I just don't understand because it was working before I upgraded by default to Lollipop but now, the plain boring font is set by default inside apps and seemingly unchangeable. I have not been able to find any information regarding this issue anywhere. Is there a savant out there to help walk me through this process to change it?
Answer: From what you're saying, I pressume you're on a 'Nightly' or unstable version of a ROM, or if its an OTA update that took you to Lollipop, there's a bug somewhere. Keep calm and wait for fixes, or if you're impatient, then behold below:
By the way With the right search keywords, I found this called Fonter:

Instead of only being able to change your entire system's font, Fonter allows you to choose separate fonts for individual apps. And with a huge library of free fonts to choose from, you're bound to find the right look for every app on your phone. - Quote from here

I have in no way tried the Fonter, but I am sure it might be the solution to your problem, for the time being, until the actual issue is fixed
However, since you say that issue of yours wasn't there initially, I will suggest you fix the underlying problem, rather than go around with a 'hack', kinda.
Comment: It wasn't there initially with a previous version of android but when I updated to Lollipop, that is when the default font was overwritten and it seems to be inside all apps as well. I thought it might just be that permissions changed or maybe I missed a setting somewhere but I have not been able to locate the problem. Anyway, I will try that suggestion for now. Thanks :)


Service Unavailable in IIS

Question: When I access a wrong call to a sql server data into my application in classical ASP I get this message in my entire site: Service Unavailable. It stopped. My site is in a remote host. Don´t know what to do. What can I tell to the "support team" of them to fix that?
Answer: If you check out Administration Tools/Event Viewer - Application log you will probably see an error message.
This should give you more information as too why the application pool died  or why IIS died.
If you paste this into your question we should be able to narrow things down a bit.
Comment: Yeah I'd start at the event log 1st especially if recycling the AppPool fails to fix the issue.
Comment: I'd disable Rapid fail protection while I investigated the error.
Answer: Whenever there are a number of subsequent errors in your asp.net page, the application pool may shut down. There's a tolerance level, typically 5 errors in 10 mins, or so. Beyond this level, IIS will stop the service. I've run into a lot of problem due to this error.
What you can do is either fix all your websites (will take time), or increase the tolerance level or just disable the auto shutdown system. Here's how
<code>Run IIS
Right click on the node 'Application Pools' in your left sidebar.
Click on the tab 'Health'
Remove the check on 'Enable Rapid Fail Protection'
</code>
or change the tolerance level.
Hope that helped.
Answer: One reason you can get this is if the application pool has stopped.
Answer: Application pools can stop if they error.  Usually after 5 errors in 5 minutes IIS shutsdown the AppPool.  It is part of the Rapid-fail protection and it can be disabled for an AppPool otherwise the AppPool has to be restarted every time it happens.
These settings can be changed by the IIS administrator.  It looks like you can setup a script to restart and app-pool so you should be able to set up a new web application (in a different app-pool) to restart your closed app-pool.  Hoster might not like that though.
Best result for you would be to catch all the exceptions before they get out into IIS.
Answer: Could be a SQL exception in your Application_Start (or similar) method in Global.asx. If the application (ASP.NET worker process) can't start, it can't run, so the worker process has to shut down.

Service Unavailable in IIS


how to access the next argument of command line parameters in bash?

Question: Say I have the following:
for i in $@; do
    echo ${i+1}
done

and I run this on shell $ test.sh 3 5 8 4, it outputs 1 1 1 1
why wouldn't ${i+1} work? I am trying to access the next argument for a list of command line arguments.
Comment: What do you mean *next argument*? Do you mean if gave 3, then you want 4?
Answer: Each character in shell may have an special meaning.
The code ${i+1} does not mean "add 1 to i".
To find what it means, execute this command:
LESS=+/'\{parameter\:\+word\}' man bash

And read:

${parameter:+word}
  Use Alternate Value.  If parameter is null or unset, nothing is substituted, otherwise the expansion of word is substituted.

And a little way above:

Omitting  the  colon  results  in  a  test only for a parameter that is unset.

As $i has a value set by the loop for i in $@; the "Alternate Value" is substituted and 1 is printed.
If you want to add 1 to the value of the arguments, do this:
for    i
do     echo "$((i+1))"
done

There is no need for the in "$@" (and get used to quoting all expansions).
$ ./test.sh 3 5 8 4
4
6
9
5

Next argument.
But that is not "the next argument" either. The core issue is with your loop, you are using the value of arguments in a loop, not an index to the arguments. You need to loop over an index i of the arguments, not the value i of each argument. Something like:
for (( i=1; i<=$#; i++)); do
    echo "${i}"
done

That will print an index, as this shows:
$ ./test.sh 3 5 8 4
1
2
3
4

Indirection
How do we access the argument at position $i?: With indirection:
for (( i=1; i<=$#; i++)); do
    echo "${!i}"
done

See the simple ! added ?
Now it runs like this:
$  ./test.sh  3 5 8 4
3
5
8
4

Final solution.
And to print both the present argument and the next, use this:
for (( i=1; i<=$#; i++)); do
    j=$((i+1))
    echo "${!i} ${!j}"
done

No, there is no simpler way than to calculate the value in the variable $j.

$ ./test.sh 3 5 8 4
3 5
5 8
8 4
4

That works for text also:
$ ./test.sh sa jwe yqs ldfgt
sa jwe
jwe yqs
yqs ldfgt
ldfgt

Comment: very well explained. Thanks!
Comment: Very helpful. You taught me.
Answer: In your example code i is the value, not the index.
You'll need the exclamation mark for using a variable value as variable.
I didn't get the (i+1) to work without defining another variable. Maybe someone can give a hint to optimize that.
check () {
  for i in $(seq $#); do
    let j=i+1
    echo "$i: i=${!i} i+1=${!j}"
  done
}

check a b c

1: i=a i+1=b
2: i=b i+1=c
3: i=c i+1=

Answer: First note that, ${i+1} is an parameter expansion pattern, which means if parameter i is Not unset or null, it will be substituted by the expansion of 1, which of course just results in 1. Hence you are getting all 1's in the output.
You need to use an arithmetic operator, not parameter expansion.
For example:
% check () { for i in "$@"; do echo $((i+1)); done ;}

% check 2 4 5 6
3
5
6
7

Comment: hi, I meant to ask how to access the next/previous argument using just `i`
Answer: I find myself using shift for the same purpose. Here's a small example taken from here:
#!/bin/bash

# This script can clean up files that were last accessed over 365 days ago.

USAGE="Usage: $0 dir1 dir2 dir3 ... dirN"

if [ "$#" == "0" ]; then
    echo "$USAGE"
    exit 1
fi

while (( "$#" )); do

if [[ $(ls "$1") == "" ]]; then
    echo "Empty directory, nothing to be done."
  else
    find "$1" -type f -a -atime +365 -exec rm -i {} \;
fi

shift

Answer: Expanding on user79743's answer above:
Suppose we want to have a argument that takes a value like --mode delete or --mode list.
When ${!i} == "--mode", we want to read the value for the following index (j or i+1) and retain it for later. Consider that on the next loop iteration that we will end up inspecting i+1 a second time (was j on previous loop, is i on the current loop).
I found that i is mutable, so we can increment it by 1 meaning that the next loop iteration will be i+2, so to speak.
I did want to say that, generally speaking, it is unwise to mutate a value while iterating it. This approach did work for me. I'm sure there are probably several (better) ways to do this.
Without incrementing i. Some indexes are inspected more than once.
# $ ./test.sh --mode delete 3 5 8 4
# [1]: --mode [2]: delete
# [2]: delete # <-- index [2] is inspected twice
# [3]: 3
# [4]: 5
# [5]: 8
# [6]: 4
for (( i=1; i<=$#; i++)); do
  if [[ ${!i} == "--mode" ]]; then
    j=$((i+1))
    MODE=${!j} # retain for later
    echo "[$i]: ${!i} [$j]: ${!j}"
  else
    echo "[$i]: ${!i}"
  fi
done

With incrementing i. Each index is only inspected once.
# $ ./test.sh --mode delete 3 5 8 4
# [1]: --mode [2]: delete
# [3]: 3
# [4]: 5
# [5]: 8
# [6]: 4
for (( i=1; i<=$#; i++)); do
  if [[ ${!i} == "--mode" ]]; then
    j=$((i+1))
    MODE=${!j} # retain for later
    echo "[$i]: ${!i} [$j]: ${!j}"
    i=$i+1 # <-- incrementing the index
  else
    echo "[$i]: ${!i}"
  fi
done


Where does the relation between simulation time and mesh step size for FDTD simulations come from?

Question: I am using Lumerical FDTD solutions to simulate a planewave through a region of space and some of my analysis requires me to know the relation between the simulation mesh step size and the time taken for the simulation to run.
The relationship between the simulation time and mesh step size, for 2D simulations, is stated on the Lumerical website as being:
$${\rm simulation\: time} \sim A(\lambda/dx)^3$$
where A is the region area, $\lambda$ is the wavelength of the light pulse, and dx is the mesh step size. I have only been able to find this relation in one textbook but neither in this textbook nor in the Lumerical web page does it explain how this relation is derived. Could someone help me understand where this relation came from?
Source of the relation stated above.
Comment: I come from a CFD perspective, but we choose a grid size such that the material cannot advect out in one time step (e.g., a fluid parcel moving at a characteristic speed should not be able to move more than 1 adjacent cell over, otherwise you may end up with negative densities). I suspect there are similar physical arguments here, but my experience is very limited in the E&M side of modeling.
Comment: @KyleKanos Yes, FDTD simulations have to obey the Courant condition which states that the light should not be able to propagate any further than one spatial step for each temporal step i.e. c∆t ≤ ∆x. I guess I'm mainly confused as to how this leads to the simulation time relation above, if it does lead to it at all.
Comment: I guess you purchased this software. If so, you may try asking the question to the technical support of the company. The page you linked shows the author, and you could ask to talk directly to this person.
Answer: Obeying the speed of light and computation time are not exactly the same. FDTD simulations take a long time because the algorithm has to solve maxwell equations for each Yee lattice unite, both for the E and H fields of course. This means multiplying a range of numbers for each cell and that takes up both time and memory in a computer.
The formula you found simply states that the simulation time grows with the size of the simulation space A and the number of grid cells per wavelength to the third power. One thing that may seem counterintuitive is the 3th power in 2D space, and where lambda suddenly comes from.
Basically we have $\frac{A}{(dx/\lambda)^3}$ , which takes the total area and divides it by the number of wavelengths per unit cell. You could write  $\frac{A}{dx^3}*{\lambda^3}$ which helps in understanding this. The third power is some sort of space-time like thing, because the number of required timesteps is linked to the Courant condition you mentioned in the comments. So 2 space dimensions + 1 time dimension, et voila.
Now we have the area dived by the unit cell size, which gives N as the total number of cells. This number is then related to wavelength, which I believe relates to the fact that this time domain method needs to run longer to cover a larger wavelength. For interference effects and resonances and wave effects this is important, and this for the 2 space and 1 time dimension.
You could stop your simulation to early, but you will get a very bad non-converged simulation result. That's why in practice, in a good simulation setup, the number of wavelengths per unit cell size matters. Usually one will choose $dx<\lambda$, so remember that this number is larger than 1! But even if your steps dx are small enough (i.e. $dx<\lambda/10$), the total simulation time needs to extend long enough so enough wavelengths are taken into account to capture all interferences and resonances and wave phenomena.
I hope this somewhat helps in the understanding and i have not made a mistake.
Comment: This explanation and even the supposition from the OP does not really make sense to me. Each cell has about the same computational requirement per timestep (evaluate grid values of neighboring cells and combine them). So, per timestep, the computation time of the whole grid should just be proportional to number of cells $N=n\cdot m=A/(dx)^2$, independent of the wavelength. Assume we have chosen Courant number C=1 the total time to reach a quasistatic state (like a standing wave) is the number of steps the wave takes between the boundaries...
Comment: ... and could be roughly estimated by the order of $T\approx \sqrt{n\cdot m}\cdot N=\sqrt{A}/dx \cdot N$, which is also independent of wavelength. So I would arrive at a total computational time of $\approx (\sqrt{A}/dx)^3$. How does this relate to the formula of the OP's reference?


Programming a Location Grid Map in C#

Question: I would like to know if there are any inbuilt controls in C# with which I can program location grid maps on a X/Y Plane.
Answer: The only thing that comes to mind is the grid view. You could arrange the columns and rows into a regular grid.
Besides that, .Net makes it very easy to place controls dynamically into containers. You could also do manual drawing which is very straightforward.
Here is an example of grid painting.
And here's an example of dynamically adding controls to a form.

Programming a Location Grid Map in C#


Neural network - meaning of weights

Question: I am using feed-forward NN. I understand the concept, but my question is about weights. How can you interpret them, i.e. what do they represent or how can they be undestrood (besied just function coefficients)? I have found something called "space of weights", but I am not quite sure what does it means.
Comment: See also http://stats.stackexchange.com/questions/93705/meaning-of-a-neural-network-as-a-black-box?rq=1
Answer: Individual weights represent the strength of connections between units. If the weight from unit A to unit B has greater magnitude (all else being equal), it means that A has greater influence over B (i.e. to increase or decrease B's level of activation).
You can also think of the the set of incoming weights to a unit as measuring what that unit 'cares about'. This is easiest to see at the first layer. Say we have an image processing network. Early units receive weighted connections from input pixels. The activation of each unit is a weighted sum of pixel intensity values, passed through an activation function. Because the activation function is monotonic, a given unit's activation will be higher when the input pixels are similar to the incoming weights of that unit (in the sense of having a large dot product). So, you can think of the weights as a set of filter coefficients, defining an image feature. For units in higher layers (in a feedforward network), the inputs aren't from pixels anymore, but from units in lower layers. So, the incoming weights are more like 'preferred input patterns'.
Not sure about your original source, but if I were talking about 'weight space', I'd be referring to the set of all possible values of all weights in the network.
Comment: It means the hidden unit's activation will be greater when the dot product between the input and the hidden unit's weights is greater. One can think of the dot product as a relative measure of similarity. Say we want to compare two vectors $x_1$ and $x_2$ (with the same norm) to a third vector $y$. $x_1$ is more similar to $y$ than $x_2$ if $x_1 \cdot y > x_2 \cdot y$, in the sense that the angle between $x_1$ and $y$ is smaller than that between $x_2$ and $y$. I say relative because it depends on the norm. See https://en.wikipedia.org/wiki/Cosine_distance.
Comment: with reference to your answer above, 'a given unit's activation will be higher when the input pixels are similar to the incoming weights of that unit (in the sense of having a large dot product)', could you please elaborate on this. Does it mean if the inputs are similar to the weights between the input and hidden unit, then hidden unit activation will be higher?
Answer: Well, it depends on a network architecture and particular layer. In general NNs are not interpretable, this is their major drawback in commercial data analysis (where your goal is to uncover actionable insights from your model).
But I love convolutional networks, because they are different! Although their upper layers learn very abstract concepts, usable for transfer learning and classification, which could not be understood easily, their bottom layers learn Gabor filters straight from raw data (and thus are interpretable as such filters). Take a look at the example from a Le Cun lecture:

In addition, M. Zeiler (pdf) and many other researchers invented very creative method to "understand" convnet and ensure it learned something useful dubbed Deconvolutional networks, in which they 'trace' some convnet by making forward pass over input pictures and remembering which neurons had largest activations for which pics. This gives stunning introspection like this (a couple of layers were shown below):

Gray images at the left side are neuron activations (the more intensity -- the larger activation) by color pictures at the right side. We see, that these activations are skeletal representations of real pics, i.e., the activations are not random.  Thus, we have a solid hope, that our convnet indeed learned something useful and will have decent generalization in unseen pics.
Answer: I think you are trying too hard on the model that does not have too much interpretability. Neural network (NN) is one of the black box models that will give you better performance, but it is hard to understand what was going on inside. Plus, it is very possible to have thousands even millions of weights inside of NN.
NN is a very big non-linear non-convex function that can have large amount of local minima. If you train it multiple times, with different start point, the weights will be different. You can come up with some ways to visualize the internal weights, but it also does not give you too much insights.
Here is one example on NN visualization for MNIST data. The upper right figure (reproduced below) shows the transformed features after applying the weights.
Answer: Simple weights are probability.
How likely a connection will give the correct or wrong answer.
Even wrong results in multilayer nets can be usefull.
Telling that something is not that..
Comment: I didn't downvote, but the answer honestly doesn't seem very useful. Yes, some network architectures (like Boltzmann machines or Hopfield networks) are inspired by statistical mechanics, but even there weights aren't probabilities, in the sense of "liming relative frequency of some event". Weights can also be negative or larger than one, probabilities can't.
Comment: curious who downvoted me, neural nets have an origin in statistics.
learn your history..
Comment: inhere the sign reflects the answer, the number the probability of it.
Comment: This is true for only limited architectures and training label types to learn.

Neural network - meaning of weights


When Thranduil tells Legolas to go north, what did he mean?

Question: At the end of the third Hobbit movie, I recall Thranduil telling Legolas to go north to look for Aragorn.  They were at Erebor, and north of that was just the Iron Hills and Forodwaith.  Aragorn would not be north of the Wood-elven Kingdom either.  What did he mean?  Am I misunderstanding the scene?
Comment: Related: http://scifi.stackexchange.com/questions/79413
Comment: He should have said "Go west, young man."
Answer: This scene and dialog was invented for the movies and doesn't occur at all in the books.
You're correct that it's difficult to reconcile with the geography of the books, and difficult to determine exactly what Thranduil may have meant.
The only reasonable explanation may be that Aragorn was at that time ranging north of Erebor, and Thranduil knew it.  Since the movies operate on a different timeline to the books, Aragorn's age of 10 in the books would be irrelevant and this is possible.
Perhaps when the extended edition of Battle of Five Armies is released, the director's commentary (or some extra scenes) may reveal more.  Until then all we can say is that we don't know what was intended.
Comment: @FeldpauschAll4 - well I'm not sure what you're asking then, because based on what we currently know it seems unanswerable without speculation.
Comment: I know this is not in the book.  I just figured they said north for a reason.  South would have made a lot more sense.
Answer: I think that Legolas was told to meet the young ranger, Aragorn, and then return to Woodland Realm. Then few years later Aragorn captured the creature, Gollum and brought him to the Mirkwood as a prisoner. Then Aragorn returned back to North. After Gollum escaped from Mirkwood, Legolas came to Rivendell to inform about it to Lord Elrond. So then he accidentally participated the council there and became one of the Fellowship of the Ring.
Answer: Strider and rangers are from the north. So when Thranduil said go to the north he somehow meant he will go and live with the rangers. Thranduil also said go to the Dunedain which by what he said is probably on the north.
Comment: They don't live North of Thranduils realm though.
Answer: Actually, I do believe the answer CAN be found in the book.
Specifically, in Appendix A of The Return of the King, it is said that:
... cut for brevity with relevant information being that Elrond confronts Aragorn about his heritage and hinting at how Arwen will be affected ...

'After a few years, Gilraen took leave of Elrond and returned to her own people in Eriador, and lived alone; and she seldom saw her son again, for he spent many years in far countries. But on a time, when Aragorn had returned to the North, he came to her...

... cut for brevity with the only other relevant mention of time being related to Gilraen's passing before the spring that followed ...

'Thus the years went on to the War of the Ring; of which more is told elsewhere...'

According to the timeline in Appendix B, this incident would likely coincide 10 plus years later in 2951 after the Battle of the Five Armies and after Elrond has disclosed to Aragorn the truth to his heritage.
That said, though the dates aren't completely matching, Thranduil's instructions for Legolas to go North - while perhaps a bit premature - makes sense...
while also hinting to the fact that it will be Aragorn who will find and capture Gollum and bring him to Mirkwood in another 60 or so years in 3017 and whose subsequent escape will be what prompts Legolas as a representative of Mirkwood and Thranduil to seek counsel from Elrond in The Fellowship of the Ring.
Comment: "Returned to the North" here means returned from the old southern kingdom (now Gondor and Rohan) to the old northern kingdom (Arnor). It doesn't mean that he went somewhere north of Erebor.
Comment: The problem is that "The North" is to the West of Erebor/Mirkwood, not to the North.
Answer: Legolas also said he rides north to Gundbald after Taurial is banished, so it could be they just don't know which way North is.  Legolas was also backwards on his directions in the Two Towers on wich way the Orch were heading with Merry and Pippin.
Comment: Galadriel should have given him a compass as a gift instead of that bow.
Answer: Aragorn is actually from Angmar he's one of the duneadain or however you spell it. Which is north of the lonely mountian
Comment: [No it isn't](https://cdn.thinglink.me/api/image/582322491238645760/1024/10/scaletowidth/0/0/1/1/false/true?wait=true)
Comment: Hi, welcome to the site. You could improve this answer by editing it to include a relevant quote as supporting evidence.
Comment: He also isn't from Angmar, a kingdom founded by the Lord of the Nazgul (also known as 'the Witch-King of Angmar' for this reason), and which destroyed the kingdom of Arnor. Which is what you presumably were thinking of, ruled by Aragorn's ancestors.
Answer: I felt like what he said about a Ranger ment the Game Shadow Of Mordor. The main character dies in battle and becomes one with the creator the rings. I think I've heard him been called strider and all. Shadow of Mordor happens Between Hobbit and the LOTR. I never got to play the game so I don't absolutely know if this is accurate but it's my best Guess. SOM takes place in The Orc strongholds and they do refer to the Orc strong holds as to the North.
Comment: Yes,  the games are not canonical.
Comment: I'm not sure the movies and the games are related…  Are they?


18v vs 12v battery question

Question: I have a few 12v LED lights that run off cigarette adapters. I wanted to be able to use my 18v drill batteries so I pulled the guts out of an old charger and added a cigarette socket. The lights work fine on 18v and are rated 12v-24v. My question is would adding a regulator to limit the voltage 12v give me longer battery life or just be wasted as heat?
Answer: If you use a switching voltage regulator you will give you about 40% longer battery life.
A linear regulator will not. 30% of the battery energy will be wasted (LEDs may be brighter).

How much you extend the battery life depends upon the voltage and current draw.
When the battery is fully charged the efficiency is nearly 90% for the chip used in this example circuit. It is important to use a regulator that is tuned to your requirements for maximum efficiency.

18v vs 12v battery question


How do I straighten out my loop cuts?

Question: In the image below all of my loop cut vertices are off track from each other. From a front ortho view they are placed very messy on the faces and are out of line with each other. How do I make them more in line with each other like the above loop cuts?
Answer: What I'm understanding is that you'd like to bring the vertices of the back face of your object to be directly behind the corresponding vertices of the front face, down global Y (since you are in Front view)
If the back faces are the same shape as your front faces, and shifted, (not rotated) with respect to the front faces, you can set your snap to Active and Vertex, select all the vertices you want to move, making a convenient vertex the last selected (and therefore active) and GShift
Y the vertices, snapping the active vertex to its counterpart in XZ.
If not, another possible move -

Select the back vertices, and (without Automatic Merge switched on)   G G slide them down their edges until they meet their front partners. (You may have to do this in more than one bite). Then  GY them to your required depth.
Or.. it may be more economical to delete the back faces, and make a brand new  extrusion in Y (EY).
It's possible that the result is not the one you're looking for..
Comment: Last solution was perfect. I deleted all the vertices behind the front facing ones and extruded them back on the Y axis. But they looked funky and uneven so I just went to specials>looptools>flatten and locked the XY axes to get the conformity I was looking for. Preciate it.

How do I straighten out my loop cuts?


iPhone, half of the screen broken, cannot perform backup

Question: I recently dropped my iPhone and half of the screen is broken. I directly ordered a new one but I cannot manage to backup my old one.
I can still interact with the bottom half but when I plug it into my Mac, it asks me for my password which contains a "1" and I cannot type it. Face ID is locked so I cannot do anything. Is there a solution for me to backup old data ? I really cannot afford to lose it all so my last resort will be to replace the screen just to make the backup...
Answer:
Connect your iPhone with a Mac(that is trusted by your iPhone) using USB cable.
open iTunes.
Select your iPhone.
Select the Backup method to your iCloud account or This Computer.

It will not ask for any passcode, but if it does, you could enter it using a Bluetooth keyboard.

Note: I am not sure if a not trusted Mac or PC connected it will work.
Also See the attached image.
Comment: Actually my Mac is a trusted device but when I plug it in, it says « Your code is required after rebooting the IPhone » (It got shut down when hitting the floor) So I'm stuck here...
Comment: There is no way I can think of in your situation to circumvent having to unlock your phone with the lock code. And for that you need a working screen. If you have the opportunity I would go to a 3rd party iPhone repair shop. Either bring your Mac (assuming it's a macBook) and ask them to just temporarily connect a screen for you. Or take your phone and ask if they have a broken but working screen from a previous replacement that they can put for you for a little money.


A short circuit in LC circuit

Question: What happened in a LC circuit when I connect two ends of the Inductor by a wire with very small resistance, at the time the current in the Inductor is  $$0 < I < I_{max}$$
Answer: Zero crossings of voltage happen where there are current maximums. That is because V = L dI/dT. The derivative is zero at maximums, whether positive or negative.
Thus, when you add that wire and 0

The wire, being non-zero inductance and resistance. will do two things. It will (dramatically) change the resonant frequency AND it will dissipate a LOT of the stored energy, causing the amplitude to decay VERY rapidly (possibly less than one cycle).
Precisely what the waveform will look like will depend on the value of the capacitor, the value of the inductor, and the resistance AND inductance of the "wire". Practically (in the real world), it will also depend on the inductor's parasitic resistance and the capacitors "effective series resistance".
Comment: So, in ideal situation, all energy stored in capacitor vanished at that time, and the current in the inductor still remained in "inductor + wire" circuit.
Answer: Just model your situation to a circuit's below, there are initial voltage on C1 and initial current on L1. And do transient analysis on it. If possible, you can transform the circuit from time domain to the s-domain.

simulate this circuit – Schematic created using CircuitLab

A short circuit in LC circuit


What is Scrum at scale?

Question: I am new to the Scrum domain and recently found a "Scrum at scale" workshop near my town. I am a software engineer more inclined to data science. How would scaled Scrum help me become better in managing projects with many stakeholders, and how is it different from standard Scrum?
Comment: Is not the purpose of the workshop to find out?
Comment: @LightnessRacesinOrbit It's good to find if workshop is for me or not beforehand.
Answer: It would not help you with multiple stakeholders.
Scrum is already meant to deal with multiple stakeholders (and a single Product Owner consolidating their needs into a single prioritized product backlog). Scrum at scale is meant to help you with projects so large that you need multiple teams.
If you want to know how to better cope with your stakeholders, a Product Owner training would be the better choice.
Comment: It's more for project management, but there might be better steps forward depending on what you want to do.
Comment: Thanks. Is scrum at scale good for moving into project management career? or Is it more for techie.
Answer: TL;DR
Scrum@Scale is a specific framework developed by Jeff Sutherland and Scrum, Inc. for scaling Scrum beyond a single team. More generally, scaled Scrum (or "Scrum at [enterprise] scale") refers to the frameworks and practices required to apply Scrum concepts across multiple teams, which is often a requirement on very large or complex enterprise projects (e.g. "at scale").
Standard Scrum already handles multiple stakeholders. Scaled Scrum frameworks target programs with multiple teams. Managing stakeholders is a the function of the Product Owner in standard Scrum, but may be part of other roles (or even belong to entire teams) in other frameworks.
The Problems
At heart, Scrum is a framework for developing a product from a singular Product Backlog serviced by one unitary Scrum team. Over time, various approaches to scaling Scrum beyond a single team have been promoted within the agile community. Regardless of the framework, they all attempt to solve one or more of the following problems:

Management of very large (or even multiple) backlogs.
Cross-team estimation practices.
Resource leveling across teams.
Inter-team communications.
Multi-product architecture.
Multi-team and multi-product integration.
Executive/stakeholder resource limitations.
Portfolio management across a complex set of programs or projects.
Metrics and reporting for multi-team efforts.

This is not an exhaustive list, but the theme of "multiple teams" is one that Scrum doesn't natively tackle.
Survey of the Scaled Scrum Landscape
Various frameworks and scaling mechanisms that are used to scale Scrum beyond a single team include:

Scrum-of-Scrums
MetaScrum
Nexus
Scrum@Scale
Large Scale Scrum (LeSS)
Scaled Agile Framework for Lean Enterprises (SAFe)

NB: SAFe uses Scrum at the team level, but is arguably not truly an attempt to scale Scrum itself at the enterprise level. Instead, it uses other mechanisms and frameworks at different organizational levels. Whether you include it in "scaled Scrum" is a matter of taste, but as one of the more well-known scaled frameworks I chose to include it here for completeness.
Other agile approaches such as Lean, Kanban, DevOps, and so forth are not included in this list as they aren't inherently based on Scrum. Nevertheless, the issues of scaling are often present regardless of the framework, and must be addressed in any multi-team or multi-departmental approach to agility.
Answer: Well, in my opinion, "scrum at scale" is trying to grapple with the real-world issue that – yes, in my opinion – "scrum is an over-simplification."  Understand this, and you'll be fine.  "Scrum" has many useful ideas for project and team organization, but it rather likes to preach.
My advice is simply: "use Scrum," because it is indeed useful, but "don't entirely believe it."  Sip the kool-aid but don't drink the entire jar.  Keep it in perspective.
Real-world software systems commonly "touch" many different organizational departments and activities, and interact with other projects in ways that impose hard constraints that no single team can solve, or necessarily even see.  Of course this does not obviate the value of a "scrum" organization and workflow within that team.
"Scrum at scale" argues that scrum-style organization should nevertheless be applied at multiple levels, so that different "scrum" teams are managed in a "scrum" fashion until one "über-scrum master" rules them all.  I will candidly express my opinion that this is effectively nonsense.  The methodology, in my candid opinion, "does not scale," and ought not be expected to do so.  Due to the time and expense inherent in all software projects, plus their over-arching influence upon the business as a whole, "this is what we have vice-presidents for," and it is why their decisions are always compromises.
=== EDIT:
In an attempt to clarify the above-expressed opinion as to "why Scrum cannot or should not scale," at Todd Jacobs' request I will now add to my previous comments without eliding them.
I would now make the observation that all projects are defined with scope-and-boundaries within which management hopes that the "Scrum" methodology will produce satisfactory results in the appointed budget and time, and with acceptable business risk.  But, if we then attempt to apply "scrum" at higher levels within the organization, we quickly reach levels of abstraction and levels of concern which impact the business as a whole, and for which the (inherently risky) "exploratory methods" championed by "Scrum" are no longer applicable or even safe.  This is what I was alluding to when I said, "that's why we have vice-presidents, and that's why their decisions are always compromises."  They don't make their fuzzy high-stakes choices based on the same principles that "scrum" holds dear – they can't, and they shouldn't.
Real-world projects are often interlocked with other projects by technical, business, business-risk and financial concerns that can't be changed, so each project must be architected to consider them.  Scrum-based teams then work within those determined boundaries in an earnest effort to self-select and self-optimize their activities.
However, careful delineation of these boundaries – which is not left up to the team – is in my opinion an essential part of the reason why "scrum" is perceived to be a workable strategy.  It is in my view a micro- strategy but not a macro- one.
It is, one might say, a "risky" approach, but when that risk is well-constrained it might prove to be a benefit.  But if the same concepts are then elevated to higher levels within the organizational tree, I believe that these risks become untenable.  We already know how to let executives make decisions at those levels.  My opinion is that we should let scrum, instead, "bloom where it is planted, and where it sometimes does bloom," namely, at the leaves of the organizational project-tree, making each project's outcome the best that scrum can make it be.
Comment: So, scrum at scale is just another buzz?
Comment: Welcome to PMSE. As written, this is largely a rant. It cites no references (of which there are many) and presents an opinion without supporting evidence. The answer could certainly be rewritten to explain why you think Scrum can't (or shouldn't) scale without coming across as an unsupported minority opinion.
Comment: Okay, Todd, I've now tried to do exactly that.  As you see, I added text to the end of the previous answer without editing its previous content.  (I felt that this was best.)  Thank you for your guidance.

What is Scrum at scale?


How to show all running processes on macOS/OS X?

Question: How do I see a list of all running processes/tasks on macOS/OS X?
Answer: Inside Terminal, you can type ps aux

Terminal is available under the utilities folder in the App folder.
Comment: Better yet, you can run `pgrep -lf .` to get all running processes with their PIDs and Names. Very useful if you want to kill a process as part of a script with `pkill -x "name"`
Answer: Applications / Utilities > Activity Monitor
Comment: @MichaelBrown - View menu.
Comment: How do I enable it to show ALL Processes? I'm an admin user but can only see my process
Answer: You can use top -o mem inside terminal, to see running processes
Answer: You can use
top -o cpu
or
top -o rsize
or
ps aux
Answer: The app /Applications/Utilities/Activity Monitor is what you're looking for. If you use the command line in Terminal, the top command is useful too. In Terminal, type man top to see the various options. Activity Monitor shows you a wealth of information about each process.
Answer: To see the process names just by themselves with quotes and new lines, try this in Terminal:
ps axc | sed "s/.*:..... /\"/" | sed s/$/\"/

Answer: Try top -o +state, it will show all the running processes in the top of the 'top', however, below it will also show the sleeping processes.
Answer: Note: This solution requires pstree to be installed from either  MacPorts (sudo port install pstree) or Homebrew (brew install pstree) first.
To understand the relationship between processes, pstree is your friend. Without any switches it will show ALL processes.
However, that produces quite some verbose output. To help narrow the search space for the issue, you can use the -u switch, to limit output to puke out only your own processes:
pstree -u YourUserName
I had high CPU activity and wanted to see what I did that was triggering it, so being able to see how processes were chained (spawned) was more interesting to me.
Anyhoo, hope this helps you narrow to isolate the cause of a system issue quicker.
Comment: Another useful option is `-w` to prevent the output to be truncated to the terminal width.
Answer: If you need something in text mode but ps and top aren't good enough for you then try htop (installable with brew install htop) — it will interactively show the list of proceses (similar to Activity Monitor), as well as allow to do the following:

filter processes by name with /
kill with k
inspect a process with lsof with L
show the process tree hierarchy with t
sort by CPU, state, priority, memory, etc with F6
display CPU load per each core
Answer: Okay, look what I found:
You can use
 - Dock
 - Launch Menu (Just press Command + Option + ESC)
 - Install special app for that (e.g. Activity Monitor)
 - Look using terminal
 - Or use console commands
and that is not the full list! I founded all these methods here: https://osxtips.net/view-processes-mac/
Ofc, you can watch by yourself for more using google, bing, etc. C:
Comment: Welcome to Ask Different. I'm sure you'll find this site has a lot to offer. Check out [How do I write a good answer?](https://apple.stackexchange.com/help/how-to-answer) on tips. - From Review


What are budget options for decks competitive in local standard tournaments?

Question: With Wizards of the Coast pushing the format again, building budget-friendly decks to compete in the local scene becomes relevant. How can one approach the construction of budget decks for competitive local play of Standard (Friday Night Magic tournaments)?
Comment: "Competitive" and "budget" are somewhat contradictory requirements. The most competitive cards are usually the least budget-friendly, precisely because everyone will want them and drive the price up.
Comment: @Hackworth while that's true, the cost of MtG cards is much more determined by whether they are popular in Commander and Modern than in Standard which does give a potential niche.
Comment: The question was flagged as opinion-based, the mater is not opinion-based, though. There is data that shows competitiveness in a deck, and budget-friendly, although relative, is not opinion-based as well. How can I better approach the question so that it can be reopened?
Comment: @pietro_molina you could define "competitive" (are you hoping to win an event, and if so, how strong a field will that event have?) and also budget (how much money are you willing to spend?).
Comment: I have to agree with Pietro here, this question was wrongly closed as opinion based. There are reams of data on the strengths of particular decks and the costs of the cards those decks use over time, that makes the answer to competitive and budget very much data driven. It could have been closed as needing details (and this was my close reason, no idea of what the budget is was given) but that's a different close reason entirely.
Answer: An attempt to write a somewhat timeless answer, rather than one which just happens to give an answer for Standard as of March 2024.

As much as possible, you want a mono-coloured deck. Basic lands are free, dual lands are not.
It's a somewhat timeless truth that aggro decks are cheap. Normally that means mono-red aggro/burn but can also mean something like white weenies or occasionally mono-black.
Look at MTG Goldfish's list of standard decks and see what's out there.

As of March 2024, this includes a mono-red aggro deck which comes in under $100 and has 5% of the metagame; some builds of the deck can be significantly cheaper. The disclaimer here is that cheap decks do tend to have an inflated metagame share precisely because they are cheap.
Answer: Generally red aggro decks are lower cost than other deck types while still being able to compete. Taken from the standard meta list published on MTGGoldfish as of the writing of this answer, mono red aggro is the only deck in the top 50+
that costs less than $100 in paper and is still meta relevant at around 5.5% of the meta.
For even more of a budget, there's a list for those too. Budget decks won't be as good, usually, as the more meta defining ones, but they definitely can stand up and put in a decent showing.

I have no affiliation with MTGGoldfish, they just tend to have pretty good and accurate resources in my experience.
Answer: If you're aiming to be competitive I'll recommend mtgtop8 instead of MTGGoldfish, since the former indexes only the winner's metagame. mtgtop8 separates decks into archetypes, but for the price of each individual deck, you'll have to click on them to find out.
If you're really aiming to be competitive, look in particular at the events listed under "last major events" because it's at major events that people are most incentivized to win. Here's the list of top decks from the last major event, the 75k Open @ Magic Con Chicago, with 511 players. You can see for example that the mono red aggro deck mentioned in Philip Kendall's and Andrew's answers didn't even place in the top 16 of that event. Among the decks that did finish in the top 8, the one linked is the cheapest - UW control @ $253.
Do note that this price tag is only a ballpark estimate, and if you really want to be competitive you'll need to tune your deck as the metagame churns, maybe even swap decks entirely (shudder) - which necessarily involves more cards and hence more $.
Comment: "Competitive at FNM" is generally a significantly lower level than "competitive at a major tournament". Yes, it can depend on your FLGS.
Comment: You may be putting too much weight on being competitive and ignoring the idea of playing on a budget. If the cheapest deck you're bringing up here is over $250 that's a big ask for a lot of people.
Comment: @Andrew one could also argue you are doing the reverse, by recommending a deck that is very underrepresented at the top tables of major tournaments. Ultimately it's really up to the OP to decide what they want to do.
Comment: @PhilipKendall it still depends on the definition. I don't know how large OP's LGS is, but if it's say 10 players, and "competitive" is defined as "within the top two", then it's still not fair to say mono red is competitive (based on recent results).
Comment: Great discussion here, would you make suggestions to make the question less speculative?


What kind of bird was painted on the Romulan Warbird featured in the "Balance of Terror" Star Trek TOS episode?

Question: What type of bird was depicted on the Romulan Warbird featured in the Star Trek: TOS episode "Balance of Terror"? I imagine Romulus has several species that would be considered worthy of being called "Warbird", though it is possible the bird chosen was found off planet. I searched through Memory Alpha without success.
Answer: Crossing into Memory Beta territory, the bird is most likely a Rihannsu eagle, which is also featured in the emblem itself of the Romulan Star Empire:

Source: See "Culture" section of Romulan Star Empire.

Excerpt: The emblem of the Romulan Star Empire is known as "the Eagle". It is a symbol of military might and honor, displayed on the bridge of every Romulan warship....The first scout parties to chart the Rihannsu's new homeworld encountered huge eagles carrying their eggs in their talons; today the Eagle grasps Romulus and Remus in its claws.
Answer: I always thought that there were Klingon birds of prey and Romulan warbirds, not Romulan  Birds of prey.
Here are images of the Romulan emblem.  Note that in those which look most like the emblems used in TNG there are two things at the top center.
https://www.google.com/search?q=Romulan+emblem&biw=1024&bih=682&source=lnms&tbm=isch&sa=X&ei=vkB2VcXkDIbwoAShn4NI&ved=0CAcQ_AUoAg
According to Memory Alpha:

The double-headed bird of prey emblem of the Romulan Star Empire was first introduced in "The Neutral Zone". The symbol was designed by Monte Thrasher. (The Official Star Trek: The Next Generation Magazine, Vol. 12, p. 54) A Romulan emblem was seen in "The Enterprise Incident", though it was never used again.

Thus we see that whatever type of bird was used in the Romulan emblem it was said by Memory alpha to be two-headed.  Thank goodness, because I think it is very vulgar for someone who claims to be an emperor to use a merely one-headed eagle as his emblem.
The bird painted on the bottom of the Romulan Warbird in "Balance of Terror" would be a one-headed bird of the same species or a different species, perhaps to show that the Praetor was of lower rank than the Romulan Emperor or Empress, just as in the Holy Roman Empire the Emperor of the Romans had a two-headed eagle and the king of the Romans had a merely one-headed eagle.
Comment: No, it's a [Romulan **bird of prey**](http://en.memory-alpha.wikia.com/wiki/Romulan_Bird-of-Prey_%2823rd_century%29). Romulan **warbirds** don't appear until the 24th century. The naming confusion stems from the fact that the first Klingon bird of prey ever shown (in ST3) was supposed to be a stolen Romulan vessel. That plot point was dropped, but the name of the ship was kept, thereby establishing that both Romulans and Klingons call one of their respective ship types **bird of prey**. (Later on, this was retroactively corroborated when ENT showed 22nd century predecessors of both types.)
Comment: Also: "Here are images of the Romulan emblem." - where? I neither see any images nor a link there.
Comment: O.H. Mapper - I don't know what happened to the images but I just added the link again.  Sorry.