Is chrome incognito mode really incognito?

Question: I opened my chrome browser today incognito mode and went to youtube and opened a video and wasn't logged in but I noticed youtube video suggestions are weirdly similar to what it would suggest when I would login. Is this an issue with my browser settings or incognito mode is just fooling us?
Comment: It just deletes the trail after you close it.
Answer: No it's not.
The default incognito page states: "...However, you aren't invisible. Going incognito doesn't hide your browsing from your employer, your internet service provider, or the websites you visit."
There are a variety of ways you could have been tracked:

IP Address association
Being logged into Google via Youtube or the
Chrome Browser
Embedded tracking linked to your localstorage
Good ol' fashioned malware


The Long Dark: Can I return to Milton after I finish episode 1?

Question: I'm playing The Long Dark. I've been tasked with climbing the mountain to get to Perseverance Mills. My question is, can I return to Milton afterwards? I have a lot of stuff hoarded and I would hate to leave it all behind.
Comment: I'm now at the same point, about to leave Milton. Did you find out the answer? Can you go back to Milton?
Answer: OK, I found out - you CANNOT return to Milton!
You can take whatever you can carry though, so take that distress pistol, those military rations and good quality tools.
Some people have complained of a bug where they lose all their gear when starting Episode 2. Here's exactly what I did to avoid it:

Descend the mountain by the rocks next to the picnic area. The Episode doesn't end as soon as you've done this - so you still have a little time.

After

 the rope snaps

You can rest and eat. Then climb the other rope to continue.

Then follow the path round the mountain until you come to a cave. Enter the cave and follow the fairly linear path. When you come to the end a cutscene will play. DON'T PRESS ANYTHING! Let the cutscene play out, and also let the credits roll. They're not that long.

Once credits have finished, you can continue. Click 'Wintermute' and then 'Resume'. An opening credits sequence will play. DO NOT SKIP! I couldn't remember if I'd seen it before, so I let it play out. Then sure enough, episode 2 started and I still had all my gear.
Comment: Thank you for sharing this!! :D I was waiting to advance, hoping you'd share what you learned. Thanks again!


Cartogram3 plugin for QGIS still working?

Question: Is the Cartogram3 plugin still working? I get an error message every time I try to run it and have heard from others that it may no longer be operational.
Comment: Plugin to what? What error message do you get? Please try and add this information to give your question a chance of being answered!
Comment: Please always state which software you use
Comment: I'm not sure about the plugin - using an older version of QGIS 3.x, it should still work. TO create cartograms, another option is the great OpenSource standalone application Scapetoad: http://scapetoad.choros.place/ - it's easy to use and you can export the results to reimport it to QGIS.
Answer: I'm able to run the plugin on QGIS 3.16 without any issue.
The recipe to install. Download code from repo https://github.com/austromorph/cartogram3 using exactly the following link https://github.com/austromorph/cartogram3/archive/refs/heads/master.zip to get a ZIP file. Then, open QGIS, go to "Plugins" > "Manage and Install Plugins..." > "Install from ZIP". Then, select the downloaded ZIP file and click on button "Install Plugin". Then go to "All" to tick "cartogram3" like below.

Close the plugins manager. Create a new QGIS project (no need to save, just for demo purpose)
Now, in the menu, go to "Vector" > "Cartogram" > "Add sample dataset" to see the following

Again, do "Vector" > "Cartogram" > "Compute cartogram". Then, choose the following in the menu

Do "Ok", wait and see the result

You may wonder why I choose to install from github repo ZIP file instead of official QGIS plugins. It's because of below clues

On the Github repository (1st screenshot), the code has been updated 4 months ago whereas the plugin has been published last time on "Sept. 24, 2019, 2:45 a.m." according to https://plugins.qgis.org/plugins/cartogram3/
Your issue may not be related but at least, you better understand my approach.


Another unknown city - postmark -Anhui?

Question: Can someone tell me the name of the city on this postal cancel? I believe it's from Anhui province from 1937, but I'm not sure.
Answer: 安徽Ānhuī 杨溪镇 Yángxīzhèn = Yángxī town
Answer: Please note that in that times, characters were written from right to left.
The postmark says

廿六年 六月 廿一

Which means 21st June, 1937 (literally, 21st, June, 26nd year. Republic of China was founded in 1912. Hence 1912 was the first year and 1937 was the 26nd year.).
The big characters in the top are

安徽
  Anhui  province

The big characters in the bottom are

揚溪鎮
  Yangxi town

Please look at the first character carefully by yourself. It may be 楊 as 楊 and 揚 are very very similar. Searching on the internet, I find there is a town by the name of 揚溪鎮 (simplified Chinese: 扬溪镇) in the county of 绩溪 (Jixi), prefecture-level city of 宣城(Xuancheng) , 安徽 province. Of course, there is still a chance that the first character is 楊 if the original name has been changed.

Another unknown city - postmark -Anhui?


How do I begin with building a Linux system from scratch?

Question: I tried to make an operating system with my on custom built kernel. It didn't work out too well. I am using Ubuntu and have downloaded Linux 3.2.7 from kernel.org . I am not trying to change the kernel in my Ubuntu system. I want to make my own OS with Grub, the Linux kernel and I want to be able to have this homebrew OS in a file type (such as iso) that I can put on a cd and boot on another computer. My question is: what exactly do I need to make this OS? Any comments or tutorials would be helpful.
Comment: The website http://www.linuxfromscratch.org has a lot of information for building your own linux distribution.
Comment: You can configure grub to boot a Linux kernel. There are many places to find out how to do that; the most authoritative of which would be the official manual(http://www.gnu.org/software/grub/manual/grub.html). Once the kernel boots, it will attempt to start a program located at `/sbin/init` (unless configured otherwise). This program can do anything you want. There are some common options to use for `/sbin/init`, such as Upstart, sysvinit, systemd, or just bash. From there, that program is in control. If it ever exits, the kernel will crash, so it should be capable of starting other programs.
Answer: Here's what you're looking for:  http://www.linuxfromscratch.org/
Comment: I agree that this is what he SHOULD be doing, and I gave it the +1.  I think what he really wants is the details of Ubuntu re-branding since it was migrated from askubuntu.
Comment: Even if you're trying to do something slightly different, Linux From Scratch is certainly the place to start.
Comment: If nothing else, LFS is an excellent learning experience.
Comment: @tshubitz I looked at LFS but it makes no sense to me. Is it a prebuilt operating system? is it a guide for making an operating system? What is it?
Comment: LFS is a guide for making a GNU/Linux operating system from the ground up. This page from the LFS site pretty much sums it up:  http://www.linuxfromscratch.org/lfs/
Answer: One place to start would be Buildroot.
What is it? It's a set of scripts / makefiles that allows you to produce a linux system literally from scratch. It pulls down all of the relevant components, builds the cross compiler on the host. - pretty much everything.
It is designed primarily for embedded work - as such, it contains uclibc rather than glibc and is missing build steps for many components, e.g. Gnome and some desktop environments - however, if you're making a live CD it is absolutely brilliant. Not limited to live CDs, of course. I say that - it does come with embedded Qt.
The latest stable version comes with grub 0.97 which might not meet your requirements.
I mention this because whilst Linux From Scratch is great in that it tells you how to complete the whole process, it's long, time consuming and requires a lot of patience. Buildroot could be adapted to include whatever you needed; as a learning experience, the ability to use the menuconfig style menus and get something that boots and works is great. You can also see how it does everything before adding later features.
In terms of configuring your kernel, I cannot more strongly recommend taking your existing config (usually available in /boot), copying it to the kernel tree as .config then running make oldconfig and stepping through the new options. The default options are pretty much guaranteed to work from your distribution; if you start absolutely from scratch you may well build something unusable.
Answer: The bare minimum you need is the kernel and some process you can run as init, along with any loaders and libraries required for the init process. You boot the kernel telling it to run the init process, and where it goes from there is your business.


how to test query

Question: I would like to run a query but just to test it and have the possibility to go back to previous state
I saw rollback transaction.
do I have just to run this command before ?
delete * from myTables
where colName = "***"

Answer: Yes, you can use BEGIN TRANSACTION ... ROLLBACK TRANSACTION to check certain queries.
I changed the double quotes (") to the valid single quotes, or apostrophes ('), and the delete * to only delete as to match the SQL Server syntax.
CREATE TABLE mytables(id INT identity(1,1) ,colName NVARCHAR(255));
INSERT INTO mytables(colName)
VALUES('***');
INSERT INTO mytables(colName)
VALUES('bla');

BEGIN TRANSACTION
DELETE FROM myTables
WHERE colName = '***';
SELECT * FROM myTables; -- Result #1
ROLLBACK TRANSACTION

SELECT * FROM myTables; -- Result #2

Result #1
id  colName
2   bla

Result #2
id  colName
1   ***
2   bla

However, sepupic is entirely right about the risk of issuing a delete on a big table.
I would only do this if I wanted to test if I needed to know exactly how long the delete would take, logging included.
In most cases the select is better for testing purposes.
Answer: Are you sure you are using SQL Server?
The correct syntax of delete should look like this:
delete from myTables
where colName = '***'

To test the result you need not to delete smth at all,
you can use an appropriate select, for your question the select would be this one:
select *
from myTables
where colName <> '***'

While it can be not a problem to begin tran, do a delete and then rollback for a table with 10 rows in test environment, it can be a problem on large volumes of data or in concurrent environment, where you'll lock your table in absence of index on colname, and delete (and its rollback) will generate a lot of transaction log since delete is fully logged operation in any recovery model.
Answer: You can't rollback a transaction once it has been committed, so you can't run this and change your mind some time later. I do sometimes use this pattern to test the results of ad-hoc update statements in SSMS before I run them properly:
BEGIN TRANSACTION
SET XACT_ABORT OFF
GO
-- statements to test the current state of the data for instance
SELECT COUNT(*) FROM TableThatShouldBeEmpty
-- statements to update data
DELETE TableThatShouldBeEmpty
-- statements to test the current state of the data after the changes
SELECT COUNT(*) FROM TableThatShouldBeEmpty
GO
ROLLBACK TRANSACTION

Once you are happy with the results change ROLLBACK to COMMIT.
This is far from 100% safe though:
Still be very careful with this in production or shared dev/test/other instances though: long-running updates will still consume resources (IO, CPU, memory) so may slow down other users and locks will be held as needed so you can still cause the delays and other issues (potentially deadlocks) that your data changing statements normally would.
Also be careful if the code you are testing calls other procedures that may cause your transaction to be rolled back and don't include extra batches (extra GOs) - you might find a called procedure kills the transaction but the next batch runs leaving there no transaction for your ROLLBACK to affect so some of your tests end up getting applied permanently and not rolled back.
As always, if you can test in a separate environment that would be much safer.
To be able to rollback after the transaction is committed, you need to take a backup first and your rollback plan is to restore the DB from that. Unfortunately that will rollback all other activity too so it is probably not suitable in shared or production environments.
Answer: If you just want to see affected records change delete to select and examine the output. If you want to use transactions, make sure autocommit is not set in your database (just to be sure). Then depending on SQL engine you are using it will be something like
begin transaction
delete from t1 where attribute1 = 'xy'
select * from t1

-- commit
OR
--rollback

if you are ok with the result type commit to confirm the transaction, if not rollback the transaction. If you're toying with something like this please always do it on non-production database.

how to test query


PGP Public Key expiration GPG

Question: I'm in the process of importing a public key from a business partner.  We have always use GPG and never had a problem.
I'm importing this key using:
gpg --import "FileName.asc"
gpg: key AC260214: public key " FileName <FileName @ FileName.com>" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)

Then when I list the public keys I get:
pub   2048s/AC260214 2014-09-05 [expired: 1977-07-06]
uid                  FileName < firstname.lastname@example.com>

We can notice the expiration date of 1977.
If I try to encrypt a file with the key, I get:
gpg: FileName < email@example.com>: skipped: unusable public key
gpg: encryption of `/wm/file/workarea/encryptionKeys/TestFiles/Test.txt' failed: unusable public key

But when I import the same public key using OpenPGP GoAnywhere I can see a valid expiration date.

I was also able to encrypt a test file.
Is there a bug with gpg and public keys that has a future date of expiration? Usually other public keys I have imported never expire.
GPG Version info
-bash-3.2$ gpg --version
gpg (GnuPG) 1.4.5
Copyright (C) 2006 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

Home: ~/.gnupg
Supported algorithms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA
Cipher: 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2

Appreciate any help.  Thanks!
Answer: It might be useful to dump the public key using http://www.pgpdump.net and see if it shows the expiration date correctly.

PGP Public Key expiration GPG


Vagrant command fails, but not if run by hand

Question: I built my first Vagrant box.
When I vagrant up the box I get this error:
tange/centos3.3 Bringing machine 'default' up with 'virtualbox' provider...
tange/centos3.3 ==> default: Importing base box 'tange/centos3'...
tange/centos3.3 ==> default: Matching MAC address for NAT networking...
tange/centos3.3 ==> default: Setting the name of the VM: centos3_default_1598053704177_14223
tange/centos3.3 ==> default: Fixed port collision for 22 => 2222. Now on port 2203.
tange/centos3.3 ==> default: Clearing any previously set network interfaces...
tange/centos3.3 ==> default: Preparing network interfaces based on configuration...
tange/centos3.3     default: Adapter 1: nat
tange/centos3.3     default: Adapter 2: hostonly
tange/centos3.3 ==> default: Forwarding ports...
tange/centos3.3     default: 22 (guest) => 2203 (host) (adapter 1)
tange/centos3.3 ==> default: Running 'pre-boot' VM customizations...
tange/centos3.3 ==> default: Booting VM...
tange/centos3.3 ==> default: Waiting for machine to boot. This may take a few minutes...
tange/centos3.3     default: SSH address: 127.0.0.1:2203
tange/centos3.3     default: SSH username: vagrant
tange/centos3.3     default: SSH auth method: private key
tange/centos3.3     default:
tange/centos3.3     default: Vagrant insecure key detected. Vagrant will automatically replace
tange/centos3.3     default: this with a newly generated keypair for better security.
tange/centos3.3     default:
tange/centos3.3     default: Inserting generated public key within guest...
tange/centos3.3     default: Removing insecure key from the guest if it's present...
tange/centos3.3     default: Key inserted! Disconnecting and reconnecting using new SSH key...
tange/centos3.3 ==> default: Machine booted and ready!
tange/centos3.3 ==> default: Checking for guest additions in VM...
tange/centos3.3     default: The guest additions on this VM do not match the installed version of
tange/centos3.3     default: VirtualBox! In most cases this is fine, but in rare cases it can
tange/centos3.3     default: prevent things such as shared folders from working properly. If you see
tange/centos3.3     default: shared folder errors, please make sure the guest additions within the
tange/centos3.3     default: virtual machine match the version of VirtualBox you have installed on
tange/centos3.3     default: your host and reload your VM.
tange/centos3.3     default:
tange/centos3.3     default: Guest Additions Version: 4.3.8
tange/centos3.3     default: VirtualBox Version: 6.1
tange/centos3.3 ==> default: Configuring and enabling network interfaces...
tange/centos3.3 The following SSH command responded with a non-zero exit status.
tange/centos3.3 Vagrant assumes that this means the command failed!
tange/centos3.3
tange/centos3.3 /sbin/ip -o -0 addr | grep -v LOOPBACK | awk '{print $2}' | sed 's/://'
tange/centos3.3
tange/centos3.3 Stdout from the command:
tange/centos3.3
tange/centos3.3
tange/centos3.3
tange/centos3.3 Stderr from the command:
tange/centos3.3
tange/centos3.3 bash: line 1: ip: command not found
tange/centos3.3 bash: line 1: ifconfig: command not found

It seems the system cannot find neither ip nor ifconfig, but when I login as vagrant the commands work just fine. And if I run:
/sbin/ip -o -0 addr | grep -v LOOPBACK | awk '{print $2}' | sed 's/://'

I get a list of network interfaces.
So why does it work when I run it by hand, but not when Vagrant tries to?
How can I change the box so this does not happen?
Vagrantfile:
# -*- mode: ruby -*-
# vi: set ft=ruby :

# All Vagrant configuration is done below. The "2" in Vagrant.configure
# configures the configuration version (we support older styles for
# backwards compatibility). Please don't change it unless you know what
# you're doing.
Vagrant.configure("2") do |config|
  # The most common configuration options are documented and commented below.
  # For a complete reference, please see the online documentation at
  # https://docs.vagrantup.com.

  # Every Vagrant development environment requires a box. You can search for
  # boxes at https://vagrantcloud.com/search.
  config.vm.box = "tange/centos3"

  # Disable automatic box update checking. If you disable this, then
  # boxes will only be checked for updates when the user runs
  # `vagrant box outdated`. This is not recommended.
  # config.vm.box_check_update = false

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine. In the example below,
  # accessing "localhost:8080" will access port 80 on the guest machine.
  # NOTE: This will enable public access to the opened port
  # config.vm.network "forwarded_port", guest: 80, host: 8080

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine and only allow access
  # via 127.0.0.1 to disable public access
  # config.vm.network "forwarded_port", guest: 80, host: 8080, host_ip: "127.0.0.1"

  # Create a private network, which allows host-only access to the machine
  # using a specific IP.
  config.vm.network "private_network", ip: "172.27.27.3"

  # Create a public network, which generally matched to bridged network.
  # Bridged networks make the machine appear as another physical device on
  # your network.
  # config.vm.network "public_network"

  # Share an additional folder to the guest VM. The first argument is
  # the path on the host to the actual folder. The second argument is
  # the path on the guest to mount the folder. And the optional third
  # argument is a set of non-required options.
  # config.vm.synced_folder "../data", "/vagrant_data"

  # Provider-specific configuration so you can fine-tune various
  # backing providers for Vagrant. These expose provider-specific options.
  # Example for VirtualBox:
  #
  config.vm.provider "virtualbox" do |vb|
  #   # Display the VirtualBox GUI when booting the machine
  #   vb.gui = true
  #
  #   # Customize the amount of memory on the VM:
    vb.memory = "512"
  end
  #
  # View the documentation for the provider you are using for more
  # information on available options.

  # Enable provisioning with a shell script. Additional provisioners such as
  # Puppet, Chef, Ansible, Salt, and Docker are also available. Please see the
  # documentation for more information about their specific syntax and use.
  config.vm.provision "shell" do |s|
    ssh_pub_key = File.readlines("../../authorized_keys").first.strip
    s.inline = <<-SHELL
      mkdir /root/.ssh
      echo #{ssh_pub_key} >> /home/vagrant/.ssh/authorized_keys
      echo #{ssh_pub_key} >> /root/.ssh/authorized_keys
      sudo apt install rsync || sudo yum install -y rsync || sudo pkg install -y rsync
    SHELL
  end
end

$ vagrant --version
Vagrant 2.2.9

Comment: There is also an [issue ticket about this on Github](https://github.com/hashicorp/vagrant/issues/11843).
Answer: There is an old and unresolved issue opened at Hashicorp, which indicates that CentOS, no matter how much it updates the repository, does not update the Base Box that has an old kernel.
The problem is that the plugin needs a package from the same Box kernel version, but this package, CentOS has already removed from the repo.
You need to add in your Vagrantfile the instruction for vbguest to update the kernel, or use an old version of the vagrant-vbguest plug:
config.vbguest.installer_options = { allow_kernel_upgrade: true }


Differentiation of geometric mean

Question: I've just encountered the following problem. Define the following geometric mean $$Y_t = \left( \prod_{k \neq i} X^k_t \right)^{1/n} $$ where $i = 1,2,...,n$ and $t$ means time. My question is how to take following differentiation $$\frac{dY_t}{Y_t}?$$ I tried several times but got stuck. I appreciate any hint or answer. Many thanks!
Comment: $\frac{dY_t}{Y_t}$? What is this notation supposed to mean? Also, show your attempts
Comment: If I understand correctly, I believe that $\frac{dY_t}{Y_t}$ means the differentiation of $Y_t$ devided by $Y_t$. I wrote $\prod_{k \neq i} X^k_t = X^1_t X^2_t ... X^{i-1}_t X^{i+1}_t ... X^n_t$ and then tried to get $\frac{dY_t}{Y_t}$ but getting overwhelmed since there are many variables.
Answer: $$\log Y_t=\frac1n\log\left(\prod_{k\ne i} X_t^k\right)=\frac1n\sum_{k\ne i}\log X_t^k$$
and
$$\frac{dY_t}{Y_t}=\frac1n\sum_{k\ne i}\frac{d X_t^k}{ X_t^k}.$$
Comment: Thanks for your response. Do you mean $d \log Y_t = \frac{dY_t}{Y_t}$? I am not sure whether we can treat $Y_t$ as a normal variable in this case or not.
Comment: @MinHaw: yes I am.
Comment: @ Yves Daoust: I got it. Thanks!

Differentiation of geometric mean


Display posts in a random order for a specific category

Question: How to show posts in a random order when an archive of a certain category is being showed like as example: mysite.com/category/name-of-specific-category?
I have searched everywhere but could not find either code or plugins that could solve this need.
Answer: You can try this:
add_action('pre_get_posts', 'randomize_category_posts');
function randomize_category_posts($query) {
    if ($query->is_main_query() && !is_admin() && is_category('name-of-specific-category')) {
        $query->set('orderby', 'rand');
    }
}

Replace name-of-specific-category with the slug of the actual category you're targeting. Once you add this code to your functions.php, it should work like a charm. Every time the page reloads, the order will be randomized again.
Comment: Thanks a lot. Is working perfectly!
Comment: No problem! @RenatoGelforte if the answer is perfectly working for you, kindly mark it as accepted so that other people that has similar issue knows where to look.
Answer: To display posts in a random order when viewing an archive of a specific category in WordPress, you can achieve this by creating a custom query using the pre_get_posts action hook. This allows you to modify the default query parameters for category archives.
Here's how you can show posts in a random order for a specific category:
Open your theme's functions.php file:
You can access this file via your WordPress dashboard by going to "Appearance" -> "Theme Editor" and selecting your theme's functions.php file.
Add the following code at the end of your functions.php file:
php code
function custom_category_archive_query($query) {
    if (is_category() && $query->is_main_query()) {
        // Replace 'your-category-slug' with the slug of the specific category
        $category_slug = 'your-category-slug';

        // Check if the current query is for the specific category
        if ($query->query_vars['category_name'] == $category_slug) {
            $query->set('orderby', 'rand'); // Set orderby parameter to 'rand' for random order
        }
    }
}
add_action('pre_get_posts', 'custom_category_archive_query');

Make sure to replace 'your-category-slug' with the actual slug of the category for which you want to display posts in random order.
Save the changes to your functions.php file.
Now, when you visit the archive page for the specified category, the posts will be displayed in random order.
Please note that using random order for category archives can make it challenging for users to find specific content, as the order will change each time they visit the page. Make sure this is the desired behavior for your website and content before implementing this solution.
Comment: Thank you very much. It is working.

Rather than editing the function.php file, I preferred to use WP-Code.

Regarding your comments regarding the experience of users visiting the site, I am well aware of the inconvenience, but it is a conscious choice limited to only one category where it is important that the order is random.

Thank you again for your help.
Comment: Seems like this is generate by AI like chatGPT. I think you just copy pasted it straight to here because you forgot to delete the "php code" bit.


What are the current major issues and controversies in clinical trials design and analysis?

Question: As per the title, I would like to know what are currently the major issues and controversies in clinical trials design and analysis.
Comment: Community wiki?
Answer: There's a lot of them and some might be the same ones people would have mentioned 10 or 20 years ago, but here's a few:

Choice of effect measure: some effect measures have good properties for estimating causal effects even under model misspecification, but may not apply to any one patient and may not transfer to patients at different levels at risk/different populations with different risk profiles (they may also be a lot less statistically efficient)

Examples: Risk difference for a binary outcome vs. odds ratio, risk difference at 1 year for survival data vs. hazard ratio for full follow-up etc.

Population average vs. individual effects: Are we more interested in what happens to individuals vs. a population average (may be the same for some models, but not for others)? Does the answer perhaps depend on the stakeholder asking the question? For population average effects, should they be for the trial population or some other population? Presumably a physician / patient is more interested in individual effects, while insurance companies or national health systems are more interested in population average (but perhaps for their particular population, rather than the population enrolled in a trial).
Choice of estimand: Under what circumstances is a treatment policy vs. hypothetical estimand sensible/of interest? Do prescribers/patients/insurers want to know what happens when people continue taking a drug or averaged across a population part of which has stopped taking a drug (because some people always do)? For answering this, does it matter why people stopped (e.g. 1) because of side effects = likely would also stop in clinical practice, 2) because they were tired of the trial procedures, but it had nothing to do with the drug under study = might not stop in clinical practice, 3) what if we don't know?)
Choice of design/data source:

How much do we want to rely on often non-randomized real world data vs. randomized trials (which could sometimes of course also be made more representative of the real world in various respects, but sometimes might already be reasonably representative)? How do we trade-off representativeness of the population vs. internal validity of the study? To what extent is it a real concern that treatment effects compared with control would truly change in different populations vs. to what extent is the potential for bias from observational data a much bigger concern (probably pretty often?)?
Can we use external control groups (including of course in the scenario with some internal randomized control), what are the best sources (other trials, real-world data sources) and what should want do to account for differences (e.g. matching on some things, which could include longitudinal history information)?

machine learning/"AI": What can these contribute and where would we not want to rely on them? E.g.

Patient identification (inclusion/exclusion) for trials and would such inclusion criteria then be reflected in labeling? Would it be appropriate to withhold drugs from those not identified by such a model?
Outcome prediction so that we adjust for it in analysis?
Somehow making trial analysis more efficient?
Finding subgroups where drugs were better/worse (the challenge is the noisiness of the process, which makes findings very shaky/hard to be sure about - can you somehow make this more stable based on incorporating prior knowledge about the world/biology/medicine/...?)
Even if we just talk about prediction purposes, under which circumstances do more complex model reliably and predictably beat simple linear/logistic/etc. regression models by a meaningful margin that justifies their use?
Can you automate endpoint assessment? E.g. assessing cancer disease progression from imaging, inferring outcomes from wearable devices etc.?
Many more ideas, some of which are completely misguided, some of which  might be good.

Model informed drug development: How far should you go? Could you (and do you want to) do the confirmatory analysis of a registration study using a pre-specified PK/PD model? If you can't fully pre-specify it, how much of a problem is it? Exactly when can you avoid running a dose finding study by PK/PD modeling (possibly incl. based on non-human data)?
How to size dose finding studies: What is a good operating characteristic of study designs to consider when looking at how large a dose finding study should be? The power to show a difference of drug vs. control is probably not it, but what is it?
Platform studies: When are which of these (multiple drugs one disease, multiple diseases one drug, multiple drugs in multiple diseases, these options but with disease sub-types...) useful/preferable to traditional development options?
Data sharing: How to make it easy, ethically appropriate, give due creditors to original researchers, how to prevent misuse? How should it be handled that people state that "data are available upon request", but they never respond to requests? How to best ensure patients' consent/that things don't happen inappropriately?
Use of published information: How can one use all sorts of information that get published, but are not original individual patient data? Examples: aggregate summary statistics, figures of information, statements in press releases that are limited to statistical significance and so on.
Appropriate summaries of safety information (such as occurrence of adverse events), where most people would agree simple percentages don't tell the full story, but what to do instead is under debate.
Answer: Randomisation: Proper randomisation is crucial for preventing selection bias and ensuring that the treatment and control groups are comparable. Inadequate randomisation can lead to skewed results and potentially erroneous conclusions. This should really not be a problem, and yet studies do get retracted for issues with randomisation. For example see here.
Sample Size: Determining the appropriate sample size is essential for ensuring that a study has enough power to detect a true effect. Too small a sample size can result in a study being underpowered and failing to detect significant differences, while too large a sample can be wasteful and unethical. This can be problematic when different sample size software gives quite different numbers for sample size. For example see here.
Blinding: Blinding (or masking) is the process of keeping trial participants, and sometimes the researchers, unaware of which treatment each participant is receiving to prevent bias. Inadequate blinding can introduce bias and affect the results of the trial. Sometimes, it may be impossible to achive proper blinding, for example in trials comparing surgical vs non-surgical interventions, different types of talking therapies, or where a treatment has distinctive side-effects.
Data Dredging: This occurs when researchers sift through data looking for statistically significant patterns, which may result in spurious findings. It's also known as p-hacking or fishing expeditions.
Missing Data: Participants often drop out of trials or miss scheduled assessments, which can result in missing data. How this missing data is handled can significantly impact the results and interpretations of the trial. Techniques such as multiple imputation can help to mitigate this issue, but that in itself has various issues in implementation, and may still result in bias.
Multiplicity: Also known as the multiple comparisons problem, this arises when researchers test multiple hypotheses or conduct multiple sub-group analyses without proper statistical adjustments, increasing the risk of false-positive findings.
Publication Bias: Positive or significant results are more likely to be published than negative or non-significant ones, leading to a biased representation of evidence in the literature.
Selective Reporting: Sometimes, researchers may report only certain outcomes from a study, omitting others that are less favourable or not statistically significant.
Conflicts of Interest: Financial or other interests can influence how a study is designed, conducted, or reported. Transparency about potential conflicts of interest is critical to the integrity of clinical research.
Ethical Considerations: There are often ethical concerns about placebo use (especially when effective treatments exist), informed consent, and the balance of risks and benefits for participants.
External Validity: The ability to generalise the results of a trial to other populations (external validity) can be limited if the study population is not representative of the broader patient population who would use the intervention.
Statistical Significance vs. Clinical Significance: There is often a debate about the interpretation of statistical significance in the absence of clear clinical relevance. A result can be statistically significant without being clinically meaningful.
Adaptive Designs: While adaptive designs can make clinical trials more flexible by allowing for modifications to the trial after it has started based on interim results, they can also introduce complexity and potential bias.
Patient-Reported Outcomes: The subjective nature of patient-reported outcomes can introduce variability and affect the reliability of the data.
Transparency and Reproducibility: The reproducibility crisis in science, where other researchers cannot reproduce the results of a study, affects clinical trials as well. There is a push for more transparency in methods and data to ensure that results can be independently verified.
Many of these issues have been known about for many years, and reflect the ongoing challenges in designing and implementing clinical trials that are robust, reliable, and ethically sound. Addressing these concerns often requires careful planning, clear protocols, and rigorous statistical analysis, as well as adherence to ethical standards and guidelines. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH), publishes global standards for the design, conduct, safety, and reporting of clinical trials to ensure that pharmaceuticals are effective and safe, facilitating international regulatory approval, and following those publications will help to mitigate most if not all of the above.


What method of teaching foreign languages is more effective?

Question: In wikipedia i found a list of methods of teaching foreign languages - language pedagogy. But it's seems that we not have a well recognized method or methods, or more effective then others, or at least teaching methods for which there a consensus among researchers? Can someone tell which theories (some points in theories) is predominant or more effective today, after i think 20 years of research in foreign language teaching? (Ex. Never translate words in L1, show images instead. Use IPA for teaching sounds of FL, never use the voice of teacher as an  example. Memorize adverbs first, then interjections, only this order work for successful foreign language learning). So, can i find a list of well established theories or recommendations somewhere?
Answer: Everybody learns languages differently, depending on how they learned their own languages, how close the language they're learning is to them, what their motivations are, how hard they work, whether they're literate, whether they're intelligent, and a whole lot of other things.
Therefore, there can be no method of teaching that will work best. Some ways will work with some students when used by some teachers. Other combinations won't. You have to try a lot and see what works with which students.
As a consequence, you should realize that no theory about foreign language teaching methodology is authoritative; most textbooks believe they are better and say so, but there's no evidence.
Answer: I would say that methods come in an out of fashion. Often this is like a pendulum swing (rote learning is popular, then falls out of fashion and is considered ineffective, then later its importance is recognized again).
Having studied the literature quite extensively, I don't think there is much settled science on the topic of methodology. There might be several reasons for this:

Teaching is an art not a science, so hard to research (it is hard to define a methodology as distinct from others and to research empirically)
As mentioned above, people learn in different ways and have different experiences
Learning a language is a complex process (not just cognitive but also social, psychological etc) so tricky to observe.

The examples you gave (Never translate words in L1, show images instead etc) are more teaching methods than an overall methodology. Statements like that, based on solid science, are few and far between in the language teaching world


How can I kickstart a group advocating digital literacy with Ubuntu?

Question: I'm currently working in a cyber cafe in Cameroon, Africa. Desktop penetration is very low here, so I wish to create a grassroots organisation with my mates to promote ICT. Where can I find materials and people interested in the project "Promote Computer Literacy and Digital Literacy with Ubuntu"?
Answer: If you can provide transportation for the shipment FOB Portland, Oregon, you could apply for a grant from a 501(c)(3) not-for-profit organization, FreeGeek.Org. See http://www.freegeek.org/about/grants for details.
Answer: Due to Customs issues this would be very difficult to achieve from scratch.

As you can see even System76 don't ship there: https://www.system76.com/home/shippinginformation/

Actually you need to find an African import company that can provide you with components (Motherborads, GPUs, RAM, HDD, Cases, .....). Mount machines and install/tweak ubuntu on them. Contact the Commerce Chamber in your city to get a list of any existing suppliers.

In another hand you can start by going through a partnership program with a company like Dell as a resseler or redistributor:
http://partnerdirect.dell.com/sites/channel/fr_cm/Partner-Programme-Information/GlobalCommercialEmergingChannel/Pages/GlobalCommercialEmergingChannel.aspx
Comment: Thank's for the reply but after months of searching over the INTERNET without successful results i have decide to start with some basics workshops for the mass in BASICS internet  hopping I CAN GET in touch with volunteers that can help us set a computer lab with LTSP UBUNTU.
please if there are people interested about the project feel free to contact me.


Python's nonlocal depends on level of hierarchy?

Question: This question is a follow-up on a question about Python variable scope. Additional questions q1, q2 and answers can be found on SO, among even more.
The official Python documentation, and PEP 3104 are supposed to explain the details, but they don't seem fully self-explanatory to me.
The topic I'm trying to solve is refactoring of code containing nonlocal/global by moving that code up/down one level of hierarchy.
What I do not understand are the implications of this sentence from the Python reference:

Names listed in a nonlocal statement, unlike to those listed in a
  global statement, must refer to pre-existing bindings in an enclosing
  scope (the scope in which a new binding should be created cannot be
  determined unambiguously).

Given the following code on global scope:

var = 0
def outer():
    global var                  # line A
    var = 1
    def inner():
        nonlocal var            # line B
        var = 2

        print('inner:', var)

    inner()
    print('outer:', var)

outer()
print('main:', var)

Execution raises an error:
SyntaxError: no binding for nonlocal 'var' found

The code works (with different semantics, of course, if either line A is commented out:
inner: 2
outer: 2
main: 0

or line B is commented out:
inner: 2
outer: 1
main: 1

However, in the above example, and since nonlocal is supposed to bind var to the "enclosing scope", I would have expected that line A binds the outer/var into global scope and line B then looks for outer/var and also rebinds inner/var to global/var. Instead it seems to not find it at all (due to the rebinding in line A, I suppose) and raise an error.
The desired result I expected was:
inner: 2
outer: 2
main: 2

Is this just one more example of the confusing state of mind of scoping in Python?
Or, to make this a constructive question:

How can such an example be written in a way that it does not matter at which level a function resides (having to exchange global with nonlocal and vice versa)?
If the functions reside at an intermediate, and unknown level of hierarchy, how could the author of outer() change the code that neither the outermost (in this case global) level, nor the inner() level have to be touched? -

In my humble understanding of the language, constructs like these (dependecies on closures) are just to be avoided. Others already have suggested to use other language features (classes, func attrs) to achieve this kind of context sensitivity.
Comment: Global and local variables are fundamentally different in Python.  `nonlocal` statements can only refer to local variables of an enclosing scope and never to global variables -- that's what `global` is for after all.  The concepts behind `global` and `nonlocal` are rather different.  Your arguments how the current state should pose a problem are entirely constructed.  My answer would be: Don't use global variables, and don't use `global`, and all mentioned "problems" (and a few more) will be gone.
Comment: "… and Py3k even added a `nonlocal`."  `nonlocal` is meant to make closures more useful.  It is unrelated to global variables.
Comment: While I generally agree to avoid using globals, others seem to find the concept so useful that Python provides the `global` keyword and Py3k even added a `nonlocal`. I'm trying to understand the implications of their combined use.
Comment: Does this answer your question? [Why doesn't Python's nonlocal keyword like the global scope?](https://stackoverflow.com/questions/16873615/why-doesnt-pythons-nonlocal-keyword-like-the-global-scope)
Answer: global and nonlocal are not meant to be combined.  They mean different things:

global means the name exists at the module level
nonlocal means the name exists in an outer lexical function scope

The reason you are getting the original exception is because you told Python that var is nonlocal (meaning it is in an outer function definition), but there is no function-level binding for var in any outer function definition because you told Python in the outer function that var was global.
Comment: "global and nonlocal are not meant to be combined" and that's exactly my problem: If not, then refactoring of code is made more difficult. Given that an innermost function uses a `nonlocal` and the immediate surrounding function as well. If the surrounding function changes the binding to `global`, then the innermost function must be changed, too. But, alas, with the syntax at hand I don't see another way. (But to use class wrappers and such)
Comment: I see your point, but it does not seem to me to be an unreasonable amount of work if you are refactoring closures into non-closures.
Answer:
How can such an example be written in a way that it does not matter at
  which level a function resides (having to exchange global with
  nonlocal and vice versa)?

It does not matter at which level a function resides. It only matters at which level the variable resides.

If the functions reside at an intermediate, and unknown level of
  hierarchy, how could the author of outer() change the code that
  neither the outermost (in this case global) level, nor the inner()
  level have to be touched?

You are asking whether it is possible for a function at an intermediate level to, by changing something in its code, to cause a variable in an inner function to alternately change something at a global scope or something in the outer function's local scope. This seems like a really weird thing to be able to do.
Comment: My point is about refactoring: If the middle function together with its inner function is moved one level lower, a `nonlocal` would have to be changed in `global`, even if its immediate surrounding function would also make use of the variable. Hm, I start to think I've chosen a bad example for detailing the problem I have with this syntax/scoping.
Comment: @cfi I just want to make sure I understand what you mean by: "If the middle function together with its inner function is moved one level lower". Initially, both `var` and `outer` are inside another function's block, therefore both `outer` and `inner` use `nonlocal var`. By moving the "middle function together with its inner function one level lower" you mean moving both `var` and `outer` closer to the global scope? And if this new scope for `var` and `outer` were the global scope, you would have to change both the `nonlocal var` in `outer` and in `inner` to `global var`?


Locating my backup files

Question: I have just installed ubuntu. I used to run XP and have backed up all my files to a WD backup drive which is connected to my wireless router. Trouble is, I do not know how to access this drive. My Android phone sees them but I do not know how to this with Ubuntu applications. Any suggestions/guidance will be most appreciated. Thank you.
Comment: Show us what your phone is "seeing". Also the Sharing page of the router would be helpfull.
Comment: How did you access them from windows?
Answer: Use your file manager (nautilus, pcmanfm ..) And search for the word network, or put  smb://  in the address bar.
If the address bar is locked use Ctrl+L to unlock it
By default the samba client is already installed on Ubuntu, but if it is not, just install it; in terminal type:
sudo apt-get install samba

Locating my backup files


How does Carapace Armor look with genetic manipulations?

Question: As soon as you use MELD to manipulate a soldier genetically, he gets new armor. All of the new armor-decos are sleeveless. How does it look when I equip a genetically manipulated soldier with carpace armor? Will it also become sleeveless or does it more look like the normal one?
Comment: On a side note, there's a mod to "correct" that and allow you to visually identify armor types easily: [revenge of the sleeves](http://www.nexusmods.com/xcom/mods/411/).
Answer: The Carapace Armour will become sleeveless on genetically manipulated units.
Comment: When customised you get a choice of different shoulder and elbow protection. As shown on my heavy & sniper on the left, http://steamcommunity.com/sharedfiles/filedetails/?id=196761582
Comment: Hey, thank you for the answer and also for the effort of taking a screenshot!!! :-)
Comment: More generally, all the armors have the sleeveless look on genetically modified soldiers.
Comment: I actually find it quite hard the tell the armours apart on the battlefield when they're restyled for gene-modded soldiers. Except arcangel.


How to bypass "enter SIM PIN" screen on Android Marshmallow?

Question: The phone can't be accessed before PIN code is entered, the only alternative method is to remove the SIM card entirely. I haven't found a key combination that works on this version of Android.
Enter SIM PIN screen on Android 6.0.1:
Comment: same question for PUK request. How to use phone with Wifi only while waiting for the PUK/PIN.
Answer: Why not enter the PIN to access the phone.  Well, I don't think you can bypass that.  If its your SIM, I would advise you contact your service provider and they would help.
Comment: Not an answer. I asked for a bypass, I don't know the PIN code.


Proving $ \vec{V} \cdot (\vec{\nabla}\vec{V}) = (\vec{\nabla}\cdot\vec{V})\vec{V} $ using index notation

Question: In my fluid mechanics course we encounter a lot of vector calculus problems, one of which I have been struggling with for a while now. We must prove that
$$ \vec{V} \cdot \left(\vec{\nabla}\vec{V}\right) = \left(\vec{\nabla}\cdot\vec{V}\right)\vec{V} $$
solely using summation/index notation. $\vec{\nabla}\vec{V}$ is a second order tensor which we denote by:
$$\left(\sum\limits_{i}\hat{e}_{i}\frac{\partial}{\partial x_i}\right)\left(\sum\limits_{j}\hat{e}_{j}V_j\right).$$
I think my confusion lies in the use of $\frac{\partial}{\partial x_i}$ in a tensor since we haven't used tensors commonly before taking this course. Could someone maybe prove this and clarify how second order tensors work in general?
Comment: The reason you can't prove it is that it is not true.
Comment: I would recommend writing out the whole thing laboriously, just in order to learn, and then see how it can be captured in index notation. By "laboriously" I mean write out $\vec{\nabla} \vec{V}$ as a $3\times 3$ matrix (for the case of vectors in 3 dimensions). The first row is $(\partial V_x / \partial x, \; \partial V_y/\partial x, \partial V_z / \partial x)$.
Comment: Just to make it clear, have you proven that using normal vectors? Or are you trying to solve it using index notation directly?
Comment: @FGSUZ I think it has to be proven using normal vectors. The problem said "using summation" which is sometimes called index notation in the course. Thanks to the first answer I now know index notation to be something different than what is meant, though it is interesting to read about.
Comment: Isn't this only valid for irrotational flows and shouldn't the gradient of the vector be the transpose of the resulting rank-2 tensor?
Answer: $\def\vv{{\bf v}}
\def\del{\nabla}
\def\o{\cdot}
\def\pd{\partial}$Note that
$$[\vv\o(\del\vv)]_j
= v_i [\del\vv]_{ij}
= v_i(\pd_i v_j)$$
and
$$[(\del\o\vv)\vv]_j
= (\pd_i v_i)v_j.$$
But that
$$v_i(\pd_i v_j)\ne (\pd_i v_i)v_j,$$
in general.
(Repeated indices are to be summed over.
This is Einstein's summation notation.)
For clarity let $\vv$ be two dimensional.
For $j=1$ the claim is that
$$v_1(\pd_1 v_1) + v_2(\pd_2 v_1)
= (\pd_1 v_1+\pd_2 v_2)v_1.$$
Clearly this is false.
For example, if $\vv=[x,y]^T$ this implies that
$$x = 2x.$$
The intended claim is likely that
$$\vv\o(\del\vv) = (\vv\o\del)\vv.$$
(Note that $\del\o\vv$ and $\vv\o\del$ are completely different objects.
The first is a scalar.
The second is a scalar differential operator.)
This result can be easily proved,
$$[\vv\o(\del\vv)]_j
= v_i [\del\vv]_{ij}
= v_i(\pd_i v_j)
= (v_i\pd_i) v_j
= [(\vv\o\del)\vv]_j.$$
Answer: The space that these vectors live in has a metric $g_{ij}$. For example, if you're in Euclidean space and you're using Cartesian coordinates, then $g_{ij}$ is equal to the Kronecker delta $\delta_{ij}$. If you're using non-Cartesian coordinates (e.g. polar coordinates) or you're working in non-Euclidean space, then your metric will be different. The index notation expression for a vector is $v^i$. The dot product between two vectors is represented by:
$$\vec{a}\cdot\vec{b}=a^ig_{ij}b^j=a^ib_i$$
This is, in fact, the definition of a metric - it tells you the "distance" between the tips of two vectors. The "lowered index" vector $b_i$ is defined straightforwardly, as long as you know what your metric is:
$$b_i=g_{ij}b^j$$
If you're in Euclidean space and you're using Cartesian coordinates, then we conveniently have that $b_i=b^i$, since $g_{ij}=\delta_{ij}$. With any other metric, this is not true. For example, in 2D polar coordinates (where $\vec{b}=b^r\hat{r}+b^\theta\hat{\theta}$), our metric is defined by $g_{rr}=1$ and $g_{\theta\theta}=r^2$, with the other two elements zero. In that case, we have that $b_r=g_{rr}b^r+g_{r\theta}b^{\theta}$, so $b_r=b^r$, but $b_\theta=g_{\theta r}b^r+g_{\theta \theta}b^{\theta}$, so $b_\theta=r^2b^{\theta}$. But as long as you know what your metric is, lowering the index of a vector should be straightforward.
For the rest of this discussion, let's assume that you're working in Euclidean space, since the differential geometry in non-Euclidean space gets complicated once you start taking derivatives.
The derivative operator $\vec{\nabla}$ is notated as $\partial^i$, which is shorthand for $\frac{\partial}{\partial x^i}$. The dyadic product $\vec{\nabla}\vec{V}$ is therefore notated as $\partial^j v^i$, which is shorthand for $\frac{\partial v^i}{\partial x^j}$.Putting all this together, the expression you need to prove is written as:
$$v^ig_{ij}\partial^kv^j=\partial^ig_{ij}v^jv^k$$
or, lowering the indices:
$$v_j\partial^kv^j=\partial_j v^jv^k$$
This should be enough information to start the proof.
Comment: Thanks for the elaborate answer, this way of solving it goes over my head though. Could you provide some reference on this notation and metrics?
Comment: This reference assumes you're working in Cartesian coordinates: http://web.iitd.ac.in/~pmvs/courses/mcl702/notation.pdf
Comment: @Brentdb In order to make this any simpler, you have to make a choice of coordinate system. If you're allowed to do that in the proof, use the above reference instead. If instead you have to prove this for _any_ choice of coordinate system, you have to allow for an arbitrary metric.
Comment: @probably_someone: Let ${\bf v} = [x,y]^T$. Then $v_j\partial^1 v^j = x$, $(\partial_j v^j)v^1 = 2x$, and $\partial_j(v^j v^1) = 3x$.


What is the full name of this Cinelli bike model?

Question:

Tell me, does anyone know the full name of this Cinelli bike model? I will be grateful, thank you!
Comment: Anyway, you can be certain you have a high quality frame when it is made with such a fancy bottom bracket
Answer: A-ha! but it's not a Cinelli.
A frame builder has built this using commercially available lugs and shells including the very famous Cinelli bottom bracket shell.
The frame builder is most likely to be Presti, as stamped at the top of the seat stay.

These images are from the Cinelli page for the Supercorsa frameset.
Comment: That is some magnificent spotting !
Comment: But Presti did not find such a manufacturer. In my opinion, the name is written at this place, such as Celo Europa Colnago. There is also a "C" mark on it and on the fork. And his frame is very similar to mine. Also in my logo on the fork there is a part of the Colnago logo. Still, I think my bike has a certain model (I would like to believe).
Comment: @СтасСклюев There are many manufacturers that use this bottom bracket, often quite small or Artisan builders. Presti may be a pre-internet era small manufacturer that only lasted a few years, some of them are like this. The only thing you have for certain is that the Cinelli bottom bracket dates the bike to after 1984


Multi Member LLC Fraud

Question: My husband is part of a multi member (2 members) LLC for recovery houses. Currently they have one house and 5 or 6 men living there.  The rent the other member has been gathering from these men is not being deposited into the business bank account.  Is it a requirement that the income be deposited into a business account?  If so, is this considered fraud or embezzlement?
Answer: Depends on where it is going. If it's being pocketed by the individuals, it's probably embezzlement. If it's simply being spent as fast as it comes in, or faster, it may be entirely normal for that sort of operation.
There should be a set of ledgers, on paper or in a computer, recording exactly when and how money comes in and goes out. That's the first place to look for whether money is actually missing or not... with the awareness that books can be forged, so they need to be scrutinized carefully. This is one reason a periodic audit is desirable.
A friend of mine nearly lost her veterinary practice to a bookkeeper who was embezzling, so it does happen. But it could also be honest incompetence or carelessness. By all means investigate, but what you've said is reason to dig deeper, not (yet?) reason to accuse.
Answer:
Is it a requirement that the income be deposited into a business
account?

The account to be used for the various transactions should be defined by the partners. The designation of a business account is a designation by a bank. The limits on monthly transactions and number of people who can move funds for a business account are different than those for a personal account.
The partners should establish an account that meets their needs regarding number of transactions, and the number of people who can make withdraws.
In general you don't want the partners income and expenses to move through accounts not controlled by the business, it makes it harder to track for accounting and taxes.

Multi Member LLC Fraud


execution reverted 0x contract on goerli for swap but every transaction fails while giving me the error? although tx object is fine

Question: i am getting the same error on every transaction and its on goelri network, furthermore not supoorting much of pairs. Attaching the image for reference
Answer: Doesn't look like any calls have succeeded to that contract since migrate was called over a year ago.
Looking at their documentation seems like this is the goerli address: 0xf91bb752490473b8342a3e964e855b9f9a2a668e

Ethereum Mainnet (Chain ID: 1) ExchangeProxy:
0xdef1c0ded9bec7f1a1670819833240f027b25eff ... Goerli Testnet (Chain
ID: 5) ExchangeProxy: 0xf91bb752490473b8342a3e964e855b9f9a2a668e

https://0x.org/docs/developer-resources/contract-addresses
Simulating your data to that address, the function sig is found and call is made, though it failed at a later stage with "revertWithData", "OrderNotFillableError".
You should be able to work through the issues using that contract address.


How to calculate median of distributed data?

Question: How to find the median (or approximate median) of n chunks of values. The values in each chunk can be assumed to have been sorted if it helps. In addition, the existence of a histogram for each chunk is allowed.
Comment: Reading your question literally, the answer is: ignore the subsetting of your data into chunks, and simply take the median of the entire pooled dataset. Perhaps I am misunderstanding the question. Can you not simply take the median of the set of all values in your dataset? Why does it matter that the data are in "chunks"? Is there some part of this structure that you hope to preserve?
Comment: Are you saying that your values are somehow aggregated? In what format are your data?
Answer: I first assume you do not have the possibility to save all chunks and just compute the median from all values. If you do but the values are un ordered I would recommend a selection algorithm to find the median, see Selection algorithm (wikipedia).
I also assume that the chunks don't contain elements in some sequential order such that the smallest elements come in one chunk and then the larger in the next etc. At which case you only need to find the median in the middle chunk.
I think you're looking for some kind of recursive estimator of the median but to find a good estimator for this is hard. I would recommend to use some kind of frequency count which you update for each new chunk of data giving you the possibility to get the median using these counts. Depending on the amount of possible values this might become unfeasible in terms of space. But depending on the data structure used you should be able to do this for most cases.


How to make monero transfers with node.js?

Question: I'm trying to develop an application with react native to have access to monero accounts and then make some operations like get the balance, transfer and receive XMR. I found some javascript libs in the github, but some of them are deprecated, missing methods or poor documentation. I would like some help to make something like in the photo. A lib recommendation, example codes, etc.
Answer: Monero-Javascript (https://github.com/monero-ecosystem/monero-javascript) is actively maintained and easy to use. They have some example code in their repository for how to send a transaction:
<code>const monerojs = require("monero-javascript");
let walletRpc = await monerojs.connectToWalletRpc("http://localhost:38084", "rpc_user", "abc123");
await walletRpc.openWallet("sample_wallet_rpc", "supersecretpassword123");
let createdTx = await walletRpc.createTx({
  accountIndex: 0,
  address: await walletFull.getAddress(1, 0),
  amount: "250000000000", // send 0.25 XMR (denominated in atomic units)
  relay: false // create transaction and relay to the network if true
});
let fee = createdTx.getFee(); // "Are you sure you want to send... ?"
await walletRpc.relayTx(createdTx); // relay the transaction
</code>
Good luck!


Don't you bulge?

Question: In the movie Some Like It Hot (1959) when Jerry who was pretending to be a girl was walking down the aisle on train to settle in his seat, some girl told him to take off his corset and spread out. Jerry said in response that he doesn't wear one himself. The girl kind of surprised by that said, 'Don't you bulge?' Does she mean doesn't your stomach stick out? If yes, considering the movie was made almost 70 years ago, would an English native speaker say it this way or use a different expression to mean that?
Answer: I suppose a more modern-day equivalent of 'Don't you bulge?' would be

Don't you have a belly?

The woman's soft, sensual, round belly, beloved and immortalized by artists such as Rubens and Titian has surrendered, for some time, to the very flat and tight      washboard stomach or the six-pack abs.
On the other hand, a pooch belly can be quite attractive. The Urban dictionary provides a work-safe definition which I rather like

Region of a females lower stomach that appears as fat around the belly button and has little or no lovehandles. Women sometimes develop one after childbirth even if they are skinny. Other women develop one from age or lack of exercise which is normal and affects all bodytypes in varying degrees. Can make some women look more desireable even if they feel the opposite or try to cover it up. Also known as a pooch.
  Lucy was always slim until she had her baby and now she has the cutest pooch belly.

Apparently, the term has been in use since at least 2009.

Source: Swimsuits to hide Belly Pooch 2017
Comment: I remember our ob/gyn using this term in 2003 to describe a pregnant belly!
Answer: I wouldn't say 'Don't you bulge?' It does sound old-fashioned; it might have been intended as comical even in the movie. The word bulge itself is still a usable verb (and noun) today, and there is a common idiom related to reducing weight (see below). My friends don't wear corsets, and I don't know anybody who does. So it's not easy to think of an equivalent. Something like 'Won't you stick out?' doesn't seem appropriate. If it is someone you know really well, you might be able to say Won't that make you look overweight?
If someone is on a weight-reducing diet, he or she can readily use the idiom I'm fighting 'the battle of the bulge'. Here, bulge refers to that part of the body which shows the quality of "fatness" (and that can differ from person to person, but can include the stomach, thighs, buttocks). This idiom is a takeoff (definition 2) of the name of the World War 2 campaign called the battle of the Bulge. See also History dot com.
Comment: Also, "bulge" is itself a funny-sounding word.

Don't you bulge?


How can rigid body have more than 1 speed?

Question: I have a doubt that circular ring is a rigid object and we know every point on the rigid obj must have same velocity or speed. But in case of pure rolling of sphere or others we can find topmost point has velocity 2v lowermost have 0 how's that possible..i am not able to visualise it.
Answer: It's not true that "every point on the rigid obj must have same velocity or speed."  As you pointed out, if the body is rotating, this is not the case. If the body does have the same velocity at every point, it simply means it is moving in pure translation with no rotation.
Answer: You are confusing linear velocity with angular velocity.  Consider a circular rigid body rolling in a plane without slipping.
The points in a rotating rigid body do not all have the same linear velocity.  Let V be the velocity of the center of mass (CM).  As you state, the velocity at the top is 2V, twice the velocity of the center of mass. (And the instantaneous velocity of the point on the surface is 0.) The points in the body have different linear velocities.
It can be shown that in general every point in a rigid body is rotating around every other point in the rigid body with the same unique (instantaneous) angular velocity vector.  Advanced mechanics textbooks prove this.  This is true for general three-dimensional motion of the rigid body. For the circular body rolling in a plane, the angular velocity of the CM point is V/R where R is the radius of the object and V the velocity of the CM; the angular velocity of the point at the top is 2V/2R = V/R.  The angular velocity of the two points is the same.
Answer: A rotating rigid body has a different velocity (speed + direction) at each point on the body. Only along the rotation axis, the velocity is the same.

This is often described as a velocity field, with the interpretation of velocity (vector) only being a position function.
In the potato example above the body is rotating about an arbitrary axis through the origin O.
At each point on the potato A, B, C with position vectors $\vec{r}_A$, $\vec{r}_B$ and $\vec{r}_V$ respectively has a different velocity given by the equations
$$ \begin{aligned}
 \vec{v}_A & = \vec{\Omega} \times \vec{r}_A \\
 \vec{v}_B & = \vec{\Omega} \times \vec{r}_B \\
 \vec{v}_C & = \vec{\Omega} \times \vec{r}_C \\
\end{aligned}$$
where $\times$ is the vector cross product.
This is a direct result of the property of rigid body rotations which constrain the distances between all points on a body to be fixed. This means for example $d_{\rm AB} = {\rm distance}(\vec{r}_A,\; \vec{r}_B)$ is constant at all time frames throughout the rotation.
Note that if the perpendicular distance to the rotation axis is the same, then the magnitude of the velocity vector (i.e. the speed) of each point is the same. This is to say, every point on the outside of a rotating disk has the same speed. But the velocity is different, since the direction of motion is different for each point.
To generalize this scenario if the origin point O is also translating with a velocity vector $\vec{v}_O$, then this velocity gets added to the velocity of each point due to rotation

The resulting velocity value for each point is:
$$ \begin{aligned}
 \vec{v}_A & = \vec{v}_O + \vec{\Omega} \times \vec{r}_A \\
 \vec{v}_B & = \vec{v}_O +\vec{\Omega} \times \vec{r}_B \\
 \vec{v}_C & = \vec{v}_O +\vec{\Omega} \times \vec{r}_C \\
\end{aligned}$$
In this scenario, each point has a different speed as well as different velocity.
Comment: Literal potato, I love it
Comment: potato is not rigid
Comment: This was a joke
Comment: @Eli - nothing is rigid, but you can approximate rigidity in many cases.
Answer: . . . . we know every point on the rigid object must have same [linear] velocity . . . is not true; it is the angular velocity which is the same.
Perhaps the simplest rigid body to think about in the context of rotation is a door.
When a door is opened it is clearly the case that all parts of a door do not travel at the same velocity.
The motion of each particle which make up a rotating wheel which is not slipping relative to the ground can be thought of as the sum of the constant rotational motion about the centre of mass of the wheel and the constant horizontal translational motion as shown below.

Note that when these two motions are added together the linear velocity of the particles which make up the wheel are not the same.


Rav Sa'adyah Gaon Rolling in Snow?

Question: There is a well-known claim that Rav Sa'adyah Gaon would roll in snow daily due to an earlier incident (see, e.g., here). According to this article, the story first appears in the late 1700s. Is anyone here aware of any earlier sources (i.e. within a couple of hundred years after Rav Sa'adyah passed away), or aware of an explanation as to how he would have rolled in snow daily when the climate of the places he lived was extremely dry and hot (see, e.g., here regarding his birthplace)?
Comment: If you read in the comments above your citation in the linked page from the Ben Ish Chai, he explains how a person in a place like Bagdad can fulfill this service in actuality, but only during the winter months. He emphasizes that you don't need it to snow or to live in a cold climate. That even in Bagdad one can make sufficient ice during the winter months.
Comment: To add to @YaacovDeane, Google Iraq and snow and you'll find that it *does* snow there sometimes. More peculiar to me is that the סידורו של שבת refers to a particular source as basis for what he said - חוה"ל שער עבודת האלוקים פ"ג which as far as I can tell refers to חובות הלבבות, and yet I did not see any mention in that chapter of snow or Rasag (he is mentioned in ch. 4, though).
Comment: My intention was to ask about the daily part, not that it never ever snowed or got cold there. How many days a year on average does the temperature drop below zero there?
Comment: I'm pretty sure סידורו של שבת doesn't say it was daily. Just that it happened over a certain period of time (=winter, presumably).
Comment: And if you you the section I mentioned to you above, he's explaining that you don't need snow or even precipitation. You leave shallow trays of water on the roof over night in winter and simply collect the ice in the early morning. If you collected enough of if, and found a way to store it in some kind of cold cellar under ground, it could last you far beyond the winter. At least some in earlier generations figured out how to have ice and probably shaved ice (like snow) without ever knowing about refrigerator freezers.
Answer: The book אלפא ביתא קדמיתא דשמואל זעירא (pp. 400-407) investigates this topic and concludes that the earliest reference to the story is in סדורו של שבת by ר׳ חיים מטשרנוביץ published in 1813. The author explores the trajectory of this legend in other works consequent to this initial publication. There is no known early source for the legend.
Comment: Dies he explain why סידורו של שבת referred to חובות הלבבות? Or perhaps חוה"ל isn't חובות הלבבות?
Comment: Props to you for knowing who Rav Shmuel Ashkenazi ZT"L was and for having his sefer

Rav Sa'adyah Gaon Rolling in Snow?


Symmetric polynomials in two sets of variables

Question: Suppose $f(x_1,...,x_m,y_1,...,y_n)$ is a polynomial with coefficients in some field which is invariant under permuting the $x$'s and the $y$'s. Then $f$ can be generated elementary functions $e_k(x_1,...,x_m)$ and $e_k(y_1,...,y_n)$, or the power sum polynomials $p_k(x_1,\ldots,x_m)$ and $p_k(y_1,\ldots,y_n)$. In this way we are handling the variables $x_i$ and $y_j$ independently. My questions is when can $f$ be expanded in terms of polynomials of $x_i$ and $y_j$ together? For instance, can $f$ be generated by functions of the $mn$ variables $s_{ij}=x_i+y_j$?
Comment: 1) Is $f$ invariant under permutation that mix the $x_i$ and $y_j$? 2) What do you mean by "Expanded in terms of polynomials of $x_i$ and $y_j$ together"? 3) In your "for instance", say $m = n = 1$. Then are you asking whether $xy$ can be written in terms of $x + y$?
Comment: I still don't understand the property you're looking for. Any $f$ can be expanded in termss of polynomials of the $x_i$ and $y_j$ together, because any $f$ *is* a polynomial of the $x_i$ and $y_j$ together. I think you're trying to ask something about subrings, but it isn't clear.
Comment: 1) no, $f$ is not given to be invariant under anything that mixes $x_i$ and $y_j$. 2) if we take any symmetric function in $mn$ variables and replace them with the variables $x_iy_j$, for instance, we get such an $f$. This $f$ can be expressed as elementary functions in the $x_iy_j$, and I would like to characterize this property.
Comment: Suppose $S$ is the ring of symmetric polynomials in $mn$ variables $s_{ij}$. Then there is a map from $S$ to the polynomials which are symmetric in $x_i$ and $y_j$ separately, by sending $s_{ij}$ to $x_iy_j$. What is the image of this map? What about the cokernel? Similar questions if you replace $x_iy_j$ with some symmetric function of $x_i$ and $y_j$.
Answer: Not quite sure what you want, but the main result on symmetric functions in the variables $xy=\{x_iy_j\,\colon\,i,j\geq 1\}$ is
  $$ \langle f(xy),g(x)h(y)\rangle = \langle f,g*h\rangle,\ \ (*) $$
where the scalar product on the left is defined by
  $$ \langle f(x)g(y),a(x)b(y)\rangle = \langle f,a\rangle
       \langle g,b\rangle, $$
where the scalar product on the right is the standard one on symmetric functions. Similarly the scalar product on the right-hand side of (*) is the standard one, and $g*h$ denotes the internal product of symmetric
functions. See Enumerative Combinatorics, vol. 2, Exercise 7.78.
An equivalent formulation is
  $$ s_\lambda(xy) =  \sum_{\mu,\nu}g_{\lambda\mu\nu} s_\mu(x)
     s_\nu(y), $$
where $s_\rho$ denotes a Schur function and
   $$ g_{\lambda\mu\nu} = \langle \chi^\lambda,\chi^\mu\chi^\nu
       \rangle, $$
where $\lambda,\mu,\nu$ are partitions of $n$, $\chi^\rho$ is the
irreducible character of the symmetric group $S_n$ indexed by $\rho$,
and the scalar product is the standard one on class functions on
$S_n$.


What is the Stim color_code:memory_xyz circuit executing?

Question: In Stim's color_code:memory_xyz, the all data qubits are first initialized to the |0> state, then the Z-type stabilizer measurement circuit is executed, and finally, measurements are taken in the Z basis. There are two questions about this circuit. The first question is that it seems to only detect X errors and not Z errors; how should the circuit be modified if we want to detect Z errors(and also Y errors) as well? The second question is that it seems that the data qubits are not encoded into a code state at the beginning of the circuit; why is that?
Answer: It's executing a color code. But instead of alternating between measuring X stabilizers and Z stabilizers, it cycles between measuring X stabilizers then Y stabilizers then Z stabilizers. And it does this by starting each round by applying the a 120 degree rotation around X+Y+Z to each of the data qubits (called "C_XYZ"; it sends X to Y, Y to Z, and Z to X). This has the effect of the one round measuring $X^{\otimes 6}$, the next round measuring $Y^{\otimes 6}$, and the next round measuring $Z^{\otimes 6}$, then repeating, even though each round's operations are identical.
For details, here's the diagram output by
stim gen --code color_code --task memory_xyz --distance 5 --rounds 9 \
     | stim diagram --type detslice-with-ops-svg --tick 16:41 --filter_coords D30 \
     > tmp.svg

This shows the sensitivity regions of one of the detectors declared in the circuit. The detectors work by comparing three measurements in the same location across three rounds. Instead of using the fact that $X^{\otimes 6} \cdot X^{\otimes 6} = I$ to get a deterministic comparison when no noise is present, they're using the fact that $X^{\otimes 6} \cdot Y^{\otimes 6} \cdot Z^{\otimes 6} = -I$. That's why it's combining three measurements instead of two.
Anyways, this is just a minor variation on the concept of a color code. The upside of this variation is that it should have a higher timelike distance for the same number of rounds (because you need two measurement errors to move a detection event three rounds, instead of one error to move it two rounds). The downside is that it requires a slightly different decoder.
Comment: In that method, noise would be sampled for each stabilizer measurement of X, Y, and Z, so I think different errors would be measured for each one. Is that not a problem? Normally, I think it is necessary to perform stabilizer measurements to detect X, Y, and Z errors for a single depolarizing noise sample.
Comment: @Ian The whole point of it being a fault tolerant code is that it can survive noise that occurs while it runs (up to some threshold). Any fault tolerant circuit will have dozens of noise sources per measurement; it has to survive anyway.


AdMob add not display Ad in Android App with AndEngine

Question: I have followed all the steps for adding an AdMob Ad into my app from the link at
http://www.wikihow.com/Add-Advertisements-to-Your-Android-Applications-Using-Admob
But when I run my App it does not display the Ad. My app uses AndEngine and hence the target =android-17 as opposed to android-13 specified in the link which causes compilation errors. I added the method onCreateBundle() and wanted to test AdMob. But I get this error in logCat
in my activity_main.xml for  with the message

"Error inflating class com.google.ads.Adview. I can see that the jar file has been added to the build path.

Can you please let me know what I am doing wrong. I added the code more than 12 hours back and yet there is no display.
Answer: The problems was fixed by by clicking Project->Propoerties->Build Path-> Order & Export and then building. See
Error inflating class com.google.ads.AdView


How does the second Motor operate in this diagram?

Question:
The two motors are mounted in parallel as you can see in the picture and each one of them is connected to a gearbox through an elastic coupling. My question is : how do they operate together ? is one of them supposed to be off ? if you have any book or any website that discuss such transmissions I'd be thankful.
Answer: Three gears (and gearhousing body) in that configuration is a differential. Differentials work in both directions, connected this way they simply add the outputs together to one shaft. That is simply one of the uses of the differential. Although the reverse of this is more commonly known and is used in cars to spread the forces of one shaft to two.
Mathematically a differential works as follows:
<code>A + B = C
</code>
Since you have motors connected to A and B their combined input is the output  C. Also note this means the other motor can be not running it still works perfectly fine (since A + 0 = A = C).
And yes, before you ask, differentials can be used to do mechanical arithmetical calculations of adding or subtracting. It was used in all kinds of targetting devices in WW2.
Comment: So you're saying that both motors are supplying power at the same time, right ? how is the needed power supposed to be divided between the two of them ?
Comment: @mecheng They dont have to be on at the same time a differential works as follows input a + Input b = output c.  It does not matter if the other engine is running or not there will just be more motive force if its running.
Answer: Although I'm sure there are exceptions, I think it is common for the two motors to share the load 50-50. Adding the gearbox adds cost and complexity to the system (versus just one motor), so you are only going to do it if you get a big benefit from the second motor. If it's a 90-10 split, you might as well get just rid of the second motor and save yourself the cost.
In practice, the split may deviate from 50-50 due to slight differences between the two motors. In this case a master-slave arrangement might be used to get an exactly even split. E.g. run one motor on speed control, measure the output torque, and the run the other motor on  torque control. For a dc motor, volarge is proportional to speed and current is proportional to torque. So you run one motor on a constant voltage and then match the other motor to the same current.
Answer: Elastic couplings are going to eliminate/reduce shock loading in the gear train.
How does it work? Either the second motor is for redundancy/backup and/or additional power/torque. It's the same concept as adding more cylinders to an internal combustion engine. They apply more power to the crank shaft.


Prevent subdomains with AWS S3

Question: I am considering moving one of my very static sites to use Amazon's Simple Storage Service. I have read a few articles describing how I can load the files in and set things up so that http://www.example.com/ is directed at those files, but is there a way I can ensure that people who go to http://example.com/ get 301'd to http://www.example.com/?
Answer: Just a heads up for those who find this, S3 now support main root domain. You no longer have to do a redirect.

Prevent subdomains with AWS S3


Edge holes topology. How to make holes like this?

Question: I do not understand how to properly make edge holes for a subsurf modifier.
What I want

What I have
(Some artifact on the corners)
Answer: You can use the extrude function to do this.
Lets say you have the following mesh:

Now we need to add some extra edge loops to the area want want to extrude. This can be done by clicking CTRL + R.

Once for the top and repeat that for the bottom.

Once for the side. Do this also on the other side

Now we going to Face Select and select the part we want to extrude

Now we can extrude the selected faces by pressing E and dragging it to the position you want.
You can add a few extra edges to it to control the subdivide but I find mostly that its not needed and just creates more vertex.
Result
Answer: Try doing this first: https://youtu.be/7k-FPC78FZ8 then add your subsurf afterwards. Let me know if that works for you - I tried it and it looked fine.
Try making your model first without subsurf then add the subsurf after you've created the 'hole'. I just went to face mode selected the faces that I wanted protruding inwards and clicked 'I' to extrude and scale inwards then click 'E' to extrude inwards. Then go to modifiers and add subsurf - it seems to be fine but needs a little defining on the end - so I added an edge loop (Control R) on each end to keep the shape.
Comment: Please help us make this a better site. Add more detail to your answers, not just links.


What makes Maseratis and Aston Martin motors sound the way they do

Question: It's clear these manufacturers design their motors to sound good and the buyers expect them to sound like they sound. But mechanically, how do they manage to have such a distinct sound? Could other smaller motors have an equally pleasant sound?
Comment: "To deliver a suitable automotive symphony, engineers went to work fine-tuning various parts of the car's engine, chiefly its intake and exhaust bits, while leaving big-ticket components, like the cylinder block, alone. Changing the way the air goes in, changing the way the exhaust gasses and the sound is coming out, changing the engine management system, changing the throttle progression, those enable us to give it an Aston character rather than the AMG character" - https://www.autoguide.com/auto-news/2017/10/why-the-aston-martin-db11-v8-sounds-different-from-an-amg-with-the-same-engine.html
Answer: A lot of the European cars use what's called a flat-plane crank as opposed to a crossplane crank as seen in most American V8's. There are a few exceptions, like Ford running a cross-plane crank in some of the Mustangs. The flat-plane is so called because all of the rod journals are on the same plane with each other, where a crossplane crank has four throws at 90° to each other. The flat-plane crank configuration, along with a different firing order, as well as exhaust differences, create the different sound then what you're used to.
If by "smaller" you mean a 4-cylinder, no. The note comes about because it has more cylinders to fire per revolution of the crankshaft. A 4-cylinder is already a flat-plane crank, as all of its throws are on the same plane.
Comment: While there are some European V8s (notably Ferrari and the McLaren P1) that have a flat-plane crank both Maserati and Aston Martin use cross-plane cranks (although the upcoming Valhalla should be getting the flat-plane engine from the AMG GT range)
Comment: @motosubatsu - You may be right about the Maserati, however, my assertion is, when people start talking about how "European cars sound different" the reason is because of the flat-plan crank design. I stated "most European", because I believed the OP was asking about a "general" idea and used Maserati's and Aston Martin as names which fall in this genre.
Comment: that's my point though, flat-plane cranks *aren't* actually that common in European cars. The majority you see will actually be crossplane, and since the OP mentioned two manufacturers, neither of whom currently has a flat-plane engine in a production car I think that's unlikely to be the source of what the OP is asking about


Cannot overwrite village what should I do?

Question: Hi I want to transfer my clash from ios to android but when I typed code after it I  see this message cannot overwrite village what should I do? Thank you
Comment: Have you tried deleting all data, start the village fresh *then* try the code? It could also that you've already used the village link feature and that it hasn't updated [on your iOS' side]?
Answer: If you have bought gems in the past or you're over a Town Hall level of 4 you can not transfer a village to a new phone. I hope that this helps. I personally think that this is a dumb decision on SS' part but its worth noting this if you are to make a new account in the future.
Comment: I think that is simply not true, unless you find a link to prove me wrong. This is more related to the "iOS/Android migration". Although, personal opinion and "hope that it helps" do not belong in an Answer in Arqade. Win a bit more reputation and you will be able to comment posts !


In firebug, how do I find out all of the css styles being applied to a particular element?

Question: I'm way buried in many nested levels of css, and I can't tell which style layer/level is messing up my display. How can I find out everything that's being applied to a particular element?
Answer: Click Inspect (upper left) to select the element you want to check
then on the right panel select the tab labeled "Style". It will also tell you from which .css file that particular property comes from
Answer: Right click the element and choose "Inspect Element", then you should see the element and all of the CSS rules which contributed to it. You can modify the rules simply by clicking and editing the values to try out different things to correct problems.
Answer: Use the Inspect button. Click on the item you're interested in. On the right-hand side, Firebug shows all the styles of the element, and the file + line number they originiated from.
Find the style you're trying to apply, and see if it has a stroke through it. If it does, it's being overridden by something higher in the hierarchy.
Now you have to decide how you want to solve it. Either by making your css entry more specific to the item in question, or modifying your styles in some other manner.
Answer: from the 'CSS' tab, click on "Inspect" and then click on the element. All the applied styles (and their origin) will show up on the right hand side.


Certification in iOS development

Question: I have an experience like of around 6 years as an iOS developer but I am feeling like stuck. Is there any certification for iOS developer which can help me in getting better job or which can put me in the priority list of recruiters?
Comment: Stack Overflow Developer CV might help you with this! Also, have you tried building your resumé and applying for jobs you want?
Answer: Getting certification for completing coursework and getting hired aren't necessarily at all related endeavors. If you have been developing for some time, then ideally you have something to show on your resume and CV which will reflect not only your relevance in the marketplace, but also your potential value to the company you are applying to and hopefully interviewing with. For example, your projects on github and other verifiable accomplishments clearly demonstrating your skill set.
As for certifications with recognized market value, I suppose a good start would be Apple's website portal: http://training.apple.com. Specifically for iOS development certification, there's Apple's "Global Authorized Training Provider" Learn Quest.
It certainly couldn't hurt to learn the programming language Swift. I don't know that they have a certificate optionStanford offers a course through iTunes for iOS10. There's also the main Swift site and Apple's Swift Developer site.
...and there's online course certificates from places like Udacity: https://www.udacity.com/course/ios-developer-nanodegree--nd003
Note that Udacity's "nanodegree" program and other certification programs (including bootcamps) claim varying degrees of "money-back" and other such guarantees if the certification doesn't lead to some kind of employment (which might simply be teaching the courses). The folks I know personally that have gotten hired to full-time jobs have paid for bootcamps and gotten jobs through the contacts they've made there.
As for getting noticed by recruiters, there is LinkedIn.com and job sites like Indeed.com. Networking, however, cannot be under-rated. Find local developer groups and meetings and get to know who the people in your area are. If you've gone to college, community schools, etc. use those resources as well.
Hope that helps!

Certification in iOS development


What's the origine of this quote?

Question: This is a popular Spinoza quote
"Nothing in Nature is random...A thing appears random only through the incompleteness of our knowledge." Spinoza, Ethics I.
Yet, it is not in Ethics.
Can anyone help me trace the origin of this quote?
Answer: Spinoza, Ethics, Part 1:

Prop. XXIX. Nothing in the universe is contingent, but all things are conditioned to exist and operate in a particular manner by the necessity of the divine nature. [Latin: In rerum natura nullum datur contingens sed omnia ex necessitate divinæ naturæ determinata sunt ad certo modo existendum et operandum.]

And Note to Prop. XXXIII.:

a thing can in no respect be called contingent, save in relation to the imperfection of our knowledge. [Latin: At res aliqua nulla alia de causa contingens dicitur nisi respectu defectus nostræ cognitionis.]
Comment: Current Cambridge translation: "[T]he only reason
why a thing is said to be contingent is owing to a failure in our cognition." (Prop. 33 Scholium I)
Comment: Thank you very much. Sometime in the past, the "Nothing in Nature is random" version took off as a free translation, but surely it must refer to Prop. 33.
Comment: @BalazsAczel If this answers your question, you can accept it by clicking at the tick on the upper left side of the post.

What's the origine of this quote?


Blocks reappearing after breaking

Question: I am playing MC 1.9, in singleplayer without commands. When I break blocks they keep reappearing despite the break animation. My frame rate was low but the problem was still there after I fixed the frame rate. I have tried fixing the frame rate multiple times with no success in fixing the initial problem.
Answer: Generally, what is called "block lag" is from the game taxing the hardware being used (your computer in this case) for more RAM.
Normally, Minecraft can get away with a fairly small 2 gigabytes of RAM, but with larger modpacks, it's common to increase the assigned RAM limits to 4GB or more.
Answer: This isn't related to framerate. This is related to latency and memory issues. I have the same issue when playing myself with a large modpack like Resonant Rise or a resource pack. Note that the blocks usually eventually do disappear, but you might have to mine them again.
The problem could be related to a lack of memory in Java. You could try and assign more memory. However, I'm not sure if this fixes it.

Blocks reappearing after breaking


I messed up my bike

Question: My bike is messed up. It is the type of bike where you can not pedal backwards, like the old bikes that would brake when you pedal backwards not forwards.. However, it has 3 gears. I was riding it and accidentally pedaled backwards very hard and it came to an abrupt stop.. Now when I try to pedal the back tire is rubbing up against the frame of the bike.. What did I do? Did I knock it off alignment somehow?
Comment: There are two nuts, one on each side of the axle, that hold the rear wheel in place.  On one side the axle slipped in its slot, in spite of the nuts.  What needs to be done is to loosen the nuts, slide the axle all the way into its slots, and then retighten the nuts.
Comment: You're talking there about a coaster brake. Have a read of the following article to get an understanding of how they're meant to work, and what you might have done - [http://www.sheldonbrown.com/coaster-brakes.html](http://www.sheldonbrown.com/coaster-brakes.html)
Comment: @andrewGee - this question is now 20 months old.  Did you fix it?  What was the underlying problem?  How did it work out for you?  You're okay to provide and accept your own answer.
Answer: It sounds like the rear wheel shifted in the frame. Look closely at the axle where it connects to the frame at the dropouts, you may be able to see that it shifted.
If you have the tools, loosen the nuts holding the rear wheel in place and you'll be able to recenter the wheel in the frame. As you recenter the wheel also pull back on it to keep tension on the chain. You want the chain to be taut, but not so tight that it binds as you pedal – the drive train won't be perfect and there will be spots that are slightly tighter than others, if they chain is too tight they will bind. Finally, tighten the nuts up again and you should be good to go.
Comment: Suggestion: include info on how tight to make the chain.

I messed up my bike


How my network will differ from bitcoin

Question: I read a lot about how bitcoin clients find each other. I would like to do a fork from bitcoin and I have a question. How my network will differ from bitcoin? How the client will understand if this is bitcoin's client or mine?
Answer: This seems like a silly question. If you're going to create new software, it will work as you program it.
It will differ in exactly the ways you make it.
Answer: Firstly, it's likely another coin would use different default ports to connect to. But assuming they used the same ports, two clients try to connect to each other by a handshake style exchange of information such as what version clients they are, what service bits/things they support (e.g. segwit, etc.). So a different coin would advertise itself as a different client during that initial handshake, and wouldn't connect if it wasn't compatible.
Answer: When you make your fork, you must change the default P2P port and change the network magic bytes. The network magic bytes are four byte which are found at the start of every single network message. By changing them, you are signalling to all nodes that you are using a different network and thus any Bitcoin node that connects to you will disconnect from you and all of your coin's nodes will disconnect from Bitcoin nodes.
Changing the default P2P network port will also help as nodes will really only connect to other nodes that are using the default port.

How my network will differ from bitcoin