How do I add images to the iOS Simulator

Question: I have xcode 4.5.1 and want to add photos to the iphone 6.0 simulator but cant find it. I have  a folder named iphone simulator but it just contains 4.3.1.  It may be because some months ago I drag almost everything in the application support to my extern hard drive to save some memory. Now when I drag it back it contains the 4.3.1 which I used before. Do I have to download something on new or what should I do?
Thanks in advance!
Answer:
Run the simulator
Run Safari on the Simulator
Drag a picture onto Safari running on the Simulator, this opens the image.
Click and hold on the image, or tap on the share icon in the bottom tool bar.
You'll get an alert asking if you want to store the image to your phone
Comment: Actually, you can skip step 2, it will open Safari for you, whatever the current active app is (if any).
Comment: Actually you can drop right to the Photos app
Answer: There is a slightly faster approach than what Abizern described

Open the Simulator
Drag an image directly onto it (no need to launch Safari.app)
Safari willl launch
Long-Press the image and save it to the Simulators Camera Roll

Update for iOS9: Locally stored images can be dragged directly onto the simulator and don't have to be saved explicitly.

Please note that your images are stored here (6.1 matches the Simulator version):
~/Library/Application Suppport/iPhone Simulator/6.1/Media/DCIM/100APPLE

Unfortunately you can't just add images to that folder as they will be ignored because they're not in the image database of the Simulator. However you can get all the stored images via the Finder.
Comment: In simulator version >= 7.0, this won't work at the first time. But will work after once you have done as what 'Abizern' said. :)
Comment: @KrishnaRajSalim: Actually, with my iOS 9 Simulator this still works. Remote images can be saved like described and local images can just be dragged onto the simulator and will then show up in photos (without explicitly saving them)
Answer: With Xcode 6 is easier.
1.- Drag and drop an Image to the Simulator and the image will appear directly in the native Photos app.
Answer: You can also now do this through the command line with smctl addmedia command.
$ xcrun simctl addmedia
Usage: simctl addmedia <device> <path> [... <path>]

You can specify multiple files including a mix of photos and videos.

You can also specify multiple live photos by providing the photo and video files. They will automatically be discovered and imported correctly.

Note (you may not need to add xcrun in front of simctl depending on how command line tools are installed).
To find the correct device id, run simctl list devices
$ xcrun simctl list devices
== Devices ==
-- iOS 10.2 --
    iPhone 5 (D226CF12-6782-4D7D-9C00-2D662CF4022C) (Shutdown)
    iPhone 5s (34E0E0F8-3429-4D91-B038-ECF4FD0F3311) (Shutdown)
    iPhone 6 (9C772A68-34E3-4F3F-981C-543DE6D5D985) (Shutdown)
    iPhone 6 Plus (7848A50E-BFB5-4F19-BB31-4A56CA78AA2C) (Shutdown)
    iPhone 6s (12CF89BA-C8B2-4837-B4EB-FB24DFF1622C) (Shutdown)
    iPhone 6s Plus (3EE6CA84-8F12-4A5E-A31D-EF4BF3CCBDB2) (Shutdown)
    iPhone 7 (1EB3CE5D-849C-491C-9CAA-5E97B1BD89CE) (Booted)
    iPhone 7 Plus (94FEFD36-6EFF-4762-BD21-79B1F958F6C6) (Shutdown)
    iPhone SE (E8E8ECEB-34C0-44F0-B92E-57DCA91024F1) (Shutdown)
    iPad Retina (0DA5BF39-3DC7-49B3-BE9B-2FA756FCA725) (Shutdown)
    iPad Air (DAB9C2D3-8EBC-41DC-9C2D-0ECEC1D2FAE3) (Shutdown)
    iPad Air 2 (1E2DA170-5C2E-413C-831B-FA65524643D3) (Shutdown)
    iPad Pro (9.7 inch) (99F931A9-0708-4637-9294-6420DC7A149C) (Shutdown)
    iPad Pro (12.9 inch) (08CD02EB-C44A-4183-961A-EED89FF1C225) (Shutdown)
-- tvOS 10.1 --
    Apple TV 1080p (7EE393F2-C83E-467F-9802-3E5BFE7C2CA9) (Shutdown)
-- watchOS 3.1 --
    Apple Watch - 38mm (B8969533-D7CD-462E-9E76-511C08E8CC8E) (Shutdown)
    Apple Watch - 42mm (E16167D9-1007-438B-8812-CD97CE6ABECA) (Shutdown)
    Apple Watch Series 2 - 38mm (F59C0BB1-B4D0-47DD-B927-1BFD78DD78C0) (Shutdown)
    Apple Watch Series 2 - 42mm (7FE3AADD-94AB-46B9-A057-78F20F030999) (Shutdown)

So to add a video to my iPhone 7 simulator, I would use:
$ xcrun simctl addmedia 1EB3CE5D-849C-491C-9CAA-5E97B1BD89CE <path to video>

Comment: Thank you! I was looking for a way to do this programmatically so that running automation wouldn't require manually dumping image files onto the sim for each environment.
Comment: Best answer for live photos!
Comment: If you are getting lost in the device list (like me), and need to find the active one: `xcrun simctl list devices | grep Booted`
Answer: With the drag and drop feature you will lose all the metadata of the photos.
I've created a project that make it really easy to import assets to the simulator: MBAssetsImporter.
It enables you to import both videos and photos while preserving all the original metadata of the files.
Comment: Great little app, this is without a doubt the best way to add photos AND videos en-mass.
Answer: This is MUCH easier with the new iOS Simulator that comes with Xcode 6+ (iOS Simulator 8.1 and above.)  Now all you have to do is drag one or more photos onto the iOS Simulator window, and instead of opening Safari, the Photos app opens, and instantly adds all dragged-in photos to the device.
Answer: It's simple. Just goto photos in your iPhone simulator and drag images from your location (where the images Eg.Desktop) to IphoneSimulator. It add these picture in camera album.
Answer: Another easy way, in High Sierra with XCode 10, with your simulator running, select your photo in Photos, go the Share menu and select "Simulator".
Voilá!


Framing a knee wall in front of a half-height foundation wall with windows

Question: I have a light basement with 3'6" foundation walls with windows framed above. The finished height of the window sill is 5" above the concrete sill.
I want to frame a knee wall in front of the foundation wall with a reclaimed wood ledge shelf capping the knee wall and foundation wall. I have 1/2" of spray foam on the concrete walls and sill and want the windows trimmed with 3.5" trim. If I cap/attache the framed knee wall to the sill plate framing with  2X lumber I will not have enough space for the full trim.
Can I use galvanized corner brackets to attached the top of the framed knee wall to the concrete foundation wall and then just cap with the 3/4" reclaimed wood or does code require that I use structural lumber to cap/join the framed knee wall to the foundation wall?
If I use metal brackets to secure the framed wall, how to I anchor the reclaimed wood to the sill plate framing?
Comment: You already have the structure correct this is just for finish work? , a photo would be helpful , if non structural firing strips could be used, I question because the windows are framed in.
Answer: I believe you will want to attach 1.5" thick material to the sill plate and have that come out to the top of your knee wall. If you do not do this you will have a dickens of a time trying to adequately attach the reclaimed lumber in a secure manner to prevent it from cupping and warping over time.
With regard to the windows...why not just use a separate flat window stool at the bottom of the window and use your desired window trim on the left, right and top of the window. There is nothing to say that the apron trim under the sill board has to be a matching trim to the casing around the window. Below is a picture of one such application.

Picture Source


OpenVPN client inside Kubernetes Pod: not always connecting

Question: I've been for some days on this problem and I'm starting to run out of ideas on this one (I'm not a network expert).
I'm working on a project using OpenVPN to connect to a random external VPN provider. This project is working for month on a private dedicated server without any problem. I'm trying to switch to cloud using Kubernetes. Everything works fine... but not the VPN connection. I use a NodeJS program to start and manage VPN Connection. Whenever the connection goes down, the program tries to restart openvpn until it works (every 30 seconds). The problem is that is "restart" feature works great on dedicated server with no visible downtime, but on cloud version, the downtime goes from 5 secondes to about 10 Minutes. I see no pattern and it seems at least really random.
I've been digging for some days now and I can see the "root cause": whenever I try to restart the VPN connection, I get sometimes a "RTNETLINK answers: Network unreachable" when trying to add some routes and I don't know why for now. Here are the logs I get everytime the connection fails:

[debug]:    stdout: Fri Aug 30 13:08:16 2019 /sbin/ip route add
  [error]:    OpenVPN error: RTNETLINK answers: File exists
  [debug]:    stdout: Fri Aug 30 13:08:16 2019 ERROR: Linux route add command failed: external program exited with error status: 2
  /sbin/ip route add 0.0.0.0/1 via 172.21.20.1
  [error]:    OpenVPN error: RTNETLINK answers: Network unreachable
  [debug]:    stdout: Fri Aug 30 13:08:16 2019 ERROR: Linux route add command failed: external program exited with error status: 2
  [debug]:    stdout: Fri Aug 30 13:08:16 2019 /sbin/ip route add 18.104.22.168/1 via 172.21.20.1
  [error]:    OpenVPN error: RTNETLINK answers: Network unreachable
  Initialization Sequence Completed

I now that connection fails because I have an automatic check that gets my external IP and checks if it is my real one or one of the VPN provider.
From what I've seen, the first error is not a problem because when its the only that occurs, VPN connection is ok. But the "Network unreachable" is the sign that something went wrong. But then, after some retries every 30 secondes, it finally connects.
I first thought that I was not killing properly openvpn process thus not freeing properly some resources, but It doesn't seem to be it because just running the same command :

openvpn --config conf.ovpn --dhcp-option DNS 22.214.171.124 --auth-user-pass /path/auth.txt

Various times (and killing with a Ctrl+C), it sometimes passes and sometimes not. And my project is at risk if I can't manage to have a stable connection inside the cloud (I have more features to come and can't stay on a dedicated server).
Here are also the push from the server:

PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1 bypass-dhcp,dhcp-option DNS 198.18.0.1,dhcp-option DNS 198.18.0.2,rcvbuf 493216,sndbuf 493216,explicit-exit-notify 5,comp-lzo no,route-gateway 172.21.22.1,topology subnet,ping 20,ping-restart 40,ifconfig 172.21.23.169 255.255.254.0,peer-id 5,cipher AES-256-GCM'

And the OpenVPN config file:

client
  dev tun
  proto udp
  remote XXX.XXX.com 443
  resolv-retry infinite
  nobind
  persist-key
  persist-tun
  persist-remote-ip
  ca XXX.crt
  verify-x509-name XXX.com name
  auth-user-pass
  comp-lzo
  verb 3
  auth SHA256
  cipher AES-256-CBC
  keysize 256
  tls-cipher TLS-DHE-RSA-WITH-AES-256-CBC-SHA:TLS-DHE-DSS-WITH-AES-256-CBC-SHA:TLS-RSA-WITH-AES-256-CBC-SHA

Again, all this works properly but not on the kubernetes environment. So it must have something to do with it or my provider?
Any help to debug this would be highly appreciated.
Regards,
Answer: I spent over a day try to figure this out and almost went mad.
If you are running on AWS, there is an ec2 instance level configuration that verifies correct source destinations.
To disable it, simply go to the ec2 instance, actions-> networking-> change Source/Dest check and yes for disable.
Hope it helps.


How does Postgres know which logs have been archived?

Question: I'm asking this because Postgres was hard-stopped yesterday, and I fear that there could be partial / corrupt data in one of my archived log segments. I'd like to simply delete the logs from my slave server and just have Postgres start again from the beginning (there are only about 90 segments, so it won't take long), but I'm not sure what to do, to get Postgres to do this.
Answer: On master there is archive_status directory in pg_xlog which contains files that mark status of archiving of xlogs.
Comment: FWIW, I did delete all the archives from my slave, then deleted all the `.done` files from my master's `archive_status` directory while the server was off. When I restarted the server the archive process started like normal, but no archiving is taking place (over 40 min, and no archives have been moved - `rsync` hasn't been used once). Fortunately, I'm only using this environment to learn in, but I'd be interested to know what happened when I deleted the archive status files and started the server again.


High pitched sound from left rear of mercedes (2004) w203 sportcoupe- Debugging tips? Part replacement tips?

Question: I have a C class 1.8L Kompressor 2004 mercedes sportcoupe- very like the w203.
There is a high-pitched sound coming from the rear of the vehicle. Equally loud inside and outside drivers' door. Lower noise in front of car with & without hood open. Less noise on passenger side than driver's side.
Initially this prompted me to replace the fuel pump. The old filter was cruddy and dark brown but it appeared to be working fine.
Even after this the sound persisted although its somewhat more consistent with the new pump. During hard acceleration the noise notably & reliably decreases. The noise can occasionally be heard when at a standstill. Depressurising the fuel line according to the workshop manual appears to fix the sound issue for a while. Occasionally when leaving the car sitting unused for medium periods of time ~1 hour the sound is not present for a while, considerably longer or shorter appear quite reliably come with the noise. The sound does not appear to be affected by speed. The sound does not appear to be affected by gear. The sound can be heard occasionally (somewhat rare) when turning ignition on without engine start – assumption is that this is due to the fuel pump priming process.
This prompted a check under the rear seat drivers side tank. Both side of the tank are clean. Siphon functionality appears function as at ¼ full tank of gas the drivers side tank was empty.
The presence of the sound initially when the problem appeared to be worse at low fuel levels than high fuel levels. However now the sound persists at any fuel level.
My current suspicion for the cause of noise is fuel filter & some kind of flow restriction noise. The fuel filter is an aftermarket (mostly unmarked) 4-pronged filter, looks like it should according to the manual, and its relatively new.
Next work session will be to attempt to run the pump with the lines off the fuel filter into a standalone tank to attempt to find any kind of blockage in the line leading up to the fuel filter.
This is the first car I'm working on so even tips that may seem obvious that may help. I'm looking for help primarily for debugging tips.
Comment: Welcome to Motor Vehicle Maintenance & Repair!
Answer: Try Star Tron Diesel treatment at a 10x concentration.  It's not a solvent and it's impossible to use too much.  It might just give you the cleaning you need.  I use it plenty in my E350 and love it.  You can also combine it with some automatic transmission fluid in the gas without harming anything in the engine, at a treat rate of 4-8 oz. per 10 gallons of gas.  It's an old mechanic's trick.
I'm not sure in which country you live.  If it's the U.K., try this link.
Comment: Im in sweden. We have cleaning additives, however this is a gaoline car not a disel. So I would have to account for that. +1 for fuel additives though.


Windows 7 License deactivation

Question: Until unless the machine is not formatted till time the license is activated on particular machine. But however I want to deactivate the license from my side? is it possible or is their any way to deactivate the license without informing the user?
How to escalate the license to my Microsoft account?
Comment: I think I speak for everyone when I say: umm, what?
Answer: You do not have to deactivate a computer if you are moving your license from one computer to another.  Whether a copy of Windows is licensed is a legal concept; it is separate from "activation" which is a technical matter.
If you have a retail copy of the OS which allows moving licenses between computers, you can simply install Windows on the new computer. As long as you no longer use the previous installation, you're not violating the license agreement. If the new copy of Windows will not activate (claiming that your license has already been used on another machine), you can contact Microsoft and they will allow the activation.
If you have an OEM copy of Windows, then odds are good that the license is tied to that particular machine; the license cannot be transferred between computers. You can reinstall Windows on the same machine but you cannot use a different set of hardware instead.
Comment: You just have to use the same Motherborad MS told me.

Windows 7 License deactivation


shortest paths algorithm - why backtrack from the end node instead of starting from the starting node?

Question: I was watching a dynamic programming video by Erik Demaine . He says here https://youtu.be/OQ5jsbhAv_M?t=2133 , finding the shortest paths from S to V for all V, by guessing the node after the starting node is not the right approach, and instead should guess the node before the last node. I didn't understand his explanation. Can someone explain better why find the path backwards? It seems to me that you should get the same answer either way and both approaches are equally good.
Answer: You want to find the shortest paths $S(s,v)$ to all nodes $v$ (31:30 in the video). In other words, we are interested in computing a function $f(v) = S(s,v)$, and, as explained in lecture, you can write it as $f(v) = \min_{(u,v) \in E} f(u) + w(u,v)$. In the end, it allows you to compute all such values in one go.
If you instead consider an equation $S(s,v) = \min_{(s,u) \in E} w(s,u) + S(u,v)$, you do can find $S(s,v)$ this way. However, you won't be able to find $S(s,u)$ for all other $u$ in the process, and you'll have to run the same algorithm again for other end vertices.
Comment: Thank you. I missed the part about all V. I get it now. Since we are changing the v, we can reuse the S(s,u) computed the first time for all the remaining Vs, by starting from the end node. I can now put this question to rest and move on to next algorithm.
Comment: @ Suneel: Welcome to COMPUTER**SCIENCE** @SE. Can you please edit this point missed into the question?


If I buy V-Bucks, can I use them on other devices?

Question: If I buy V-Bucks on my mobile, will they be saved on my Switch and PS4 too? Or if I buy them on Switch, will they save on my mobile and PS4 too?
Answer: It depends on the account and platform you used to buy them.
According to Epic's FAQ:

Q: Are my V-Bucks bound to the platform I purchase them on?
A: Purchased V-Bucks are shared between PC and mobile if you've linked your account with your Epic ID. However, V-Bucks purchased on PlayStation 4, Xbox One, or Switch are not shared between other platforms.

So, in your case, having bought them on your mobile, no, you cannot use them on your Switch and PS4.


How to find publications from a particular institution in a journal?

Question: Suppose now I am interested in University A and a Journal B. I want to know how many people from University A published a paper in Journal B, and what are these papers. How to do this?
Comment: Why do you want to know this?
Comment: The information you need is public. Faculty lists are easily found. Journal indices are easily found. It's just a bit of a search and correlation. You will get some false positives, though.
Comment: @DavidRicherby Some journals are top journals in some specific fields. I want to know who in University A has published many papers in the top journals so I can roughly find out the most productive researcher with high-quality papers in some fields. This can be seen as a criterion to find a good supervisor somehow.
Answer: Unfortunately, affiliations are a mess. People in bibliometrics usually say that you have to know the institution and its various names, acronyms, institutes, and laboratories very well, to capture all publications from the institution. If you have this knowledge, set up a corresponding search query (advanced search) for Web of Science (you need to have access to this database via your institution) and add the journal as additional condition.
Another approach is to check whether the institution you look at has a publications database and you can search for specific journals in there.
Comment: Sometimes the journal's (or their publisher's) websites have search tools advanced enough to allow searching/filtering by affiliation too.
Comment: @Anyon That's true! Just make sure to capture all names, acronyms etc.
Answer: In mathematics, you should be able to do this in MathSciNet (subscription required).
Here is an example I did.
Ohio State University Math department, published in Proceedings of the American Mathematical Society.
  JOURNAL Proc Amer Math Soc
  INSTITUTION 1-OHS
I get 102 results.
You have to look up the codes for the items you want.  If I just put "Ohio State" for the institution I seem to get lots of things that are not matches.
Answer: I would suggest to use lens.org which is free, and where you can use many simultaneous conditions in order to perform the search you are talking about. It is really easy to use, so I would recommend you to give it a try.
Answer:
"I want to know how many people from University A published a paper in Journal B

I agree with the answer by FuzzyLeapfrog which is that "affiliations are a mess". The one thing I can add is that some publishing companies have specific tools to allow you to see and track affiliation data, for example the Nature Publishing Group has "nature index" which among other things, gives the list of "how many people from University A published with publishing company B":
Comment: Got a downvote after my interactions with BryanKrausse and ZeroTheHero here https://academia.stackexchange.com/q/194195/93303. Had a positive score before though, and I don't see anything wrong with this answer.
Answer: In Scopus search, you can do an "affiliations" search, and this often helps to know about the research achievements and research potential of an University..


Book on symplectic geometry

Question: Can someone please tell me some introductory book on symplectic geometry? I have no prior idea of the subject but I do know about Lagrangian and Hamiltonian dynamics (at the level of Landau-Lifshitz Vol. 1). Thanks in advance. :-)
Comment: This was on-topic in September 2010, when Math.SE did not exist. Nowadays, it is clearly off-topic.
Comment: I recommend this Book:
Yong-Geun Oh, Symplectic Topology and Floer Homology: Volume 1, Symplectic Geometry and Pseudoholomorphic Curves. I spent several months to read the book. There is second volume 2 also of this Book In 2018.https://www.amazon.fr/Symplectic-Topology-Floer-Homology-Pseudoholomorphic-ebook/dp/B010G0QAL6
Answer: If you are physically inclined, V.I.Arnold's Mathematical methods of classical mechanics provides a masterful short introduction to symplectic geometry, followed by a wealth of its applications to classical mechanics. The exposition is much more systematic than vol 1 of Landau and Lifschitz and, while mathematically sophisticated, it is also very lucid, demonstrating the interaction between physical ideas and mathematical concepts that support them. (It is also worth mentioning that Arnold was largely responsible for the reawakening of interest to symplectic geometry at the end of 1960s and pioneered the study of symplectic topology. Some of these developments were brand new when the book was first published in 1974 and are briefly discussed in the appendices).
In addition to the notes by Cannas da Silva mentioned by Dick Palais, here are further two advanced books covering somewhat different territory:

Michèle  Audin, Torus actions on symplectic manifolds (2nd edition)A
Dusa McDuff and Dietmar Salamon, Introduction to symplectic topology

A In her book, Michèle Audin herself recommends

Paulette Libermann and Charles-Michel Marle, Symplectic geometry and analytical mechanics

as a wonderful introduction to symplectic geometry.
Comment: Orbicular, you are welcome to share your insights on the books that you do not find objectionable. My own experience with both "Mathematical methods of classical mechanics" and "Torus actions on symplectic manifolds" was diametrically opposite of yours.
Comment: It's characteristic of Arnold's expository genius that even topics tangential to the book's main line of thought (e.g. differential forms, Legendre transforms, etc) are treated more intuitively, yet more briefly, here than in more specialized books. This book is packed so full of insights that you can keep reading it for years and keep learning new things from it.
Comment: Arnold's book is difficult to understand if you have not already mastered the subject. Audin's book is even worse (since she is very sloppy at times (the latest edition still has a lot of mistakes & sometimes important things are not fully explained) and uses non-standard notation).
Comment: We (a group of PhD students) went through Audin's exercises. It was horrible at times, sorry!
Answer: You can find a very nice introduction to the subject in these notes by Ana Cannas da Silva:
www.math.princeton.edu/~acannas/symplectic.pdf
Comment: It seems that the link in your post is now dead. Is it the same as this: https://people.math.ethz.ch/~acannas/Papers/lsg.pdf (published also as a part of Lecture Notes in Mathematics, [DOI: 10.1007/978-3-540-45330-7](http://dx.doi.org/10.1007/978-3-540-45330-7))
Comment: Sir, thank you for the link. The lecture notes are pretty good and exhaustive.
Answer: My favourite book on symplectic geometry is "Symplectic Invariants and Hamiltonian Dynamics" by Hofer and Zehnder. It's wonderfully written. Another lovely book (which has just been reissued as an AMS Chelsea text) is Abraham and Marsden's book "Foundations of Mechanics" which covers a lot of symplectic geometry as well as so much more...
Answer: Sternberg and Guillemin's Symplectic Techniques in Physics is one of a kind. In spite of the name it feels more like a text on mathematics than on physics, with the exception of the first motivating section of the book.
Arnold's book that Victor recommends is also one of my favorites. But much of it covers the kind of material you might find in Goldstein or Landau-Lifschitz, albeit treated from a more sophisticated and geometric point of view. If you already have that thoroughly mastered, Sternberg and Guillemin might be more what you want, especially the later parts.
Answer: For a more Lie-group focused account, you can try Robert Bryant's lectures on Lie groups and symplectic geometry which are available online here. In the final lecture he describes the h-principle and others ideas of Gromov in symplectic geometry, like pseudo-holomorphic curves.
Answer: A classic, physically inclined introduction is http://www.springer.com/us/book/9780817636951 (Structure of Dynamical Systems: A Symplectic View of Physics, by J.M. Souriau).
Comment: This book is great!!!
Answer: You can also try the book An introduction to symplectic geometry by Rolf Berndt which should be a good fit given your prerequisites.
Answer: Yet another possibility could be A Brief Introduction to Symplectic and Contact Manifolds by Banyaga and Houenou. Also Hamiltonian dynamics by Vilasi could be helpful.
Answer: Check That  Introduction to symplectic mechanics https://hal.archives-ouvertes.fr/hal-03611773/  could be helpful.

Book on symplectic geometry


Laptop Overheating - Possible Fan Malfunction?

Question: for a while now my PC has been starting to lag because of CPU throttling. Using some software, I can see that my CPU temp is usually sitting at around more than 75 degrees C. This is quite concerning because I can't watch YouTube video's or do an online class without CPU throttling lagging out my PC. The first thing that comes to my mind is that my fan isn't working (I don't even know if I have one anyways - specs). Please note that my computer has been shut off multiple times without warning (due to overheating). Any possible ideas on why this is happening? Can it be that I don't have a fan? Thanks for your help in advance.
Comment: 75 degrees is nothing for a CPU, you should only start getting worried at 90 degrees. Why do you think that the problem is overheating? Look in the Event Viewer for more information.
Comment: @harrymc I am concerned because when I simply watch a video, my cpu excels 80 degrees
Comment: maximum temp on that processor is 105°C, so it's nowhere near max. It is also a very slow CPU, so expect it to always have to work hard to keep up.
Comment: 80 degrees still doesn't explain CPU throttling or shutdown. Look in the Event Viewer for more information.
Comment: Can you provide screenshots of your CPU actually thermally throttled?  Task Manager should provide the frequency, if it's below the base clock, that means it's being throttled.  As others have indicated, 75-85 degrees centigrade, is not a temperature you should be worried about.
Answer: Remove the heatsink and re-paste the processor/heatsink. The paste assists with cooling and can dry out over time. Also purchase a can of compressed air and use it to clean the heatsink fins.


Expresso Store No tax option

Question: I am new to V2 of Store and wondering how to make a product tax free?  I understand you may have to use categories not but I do not see anything in the docs or in the tax settings that shows how this is done.  Any help?
Comment: Hi Peter, what was your fix for this we have a similar conundrum
Answer: When you create or edit a tax rate in the Store → Settings area, there is a Match Categories field.
So you either select all of your categories, minus the Tax-free category you've created; or, you create a single Taxable category, and use that as the way to assign tax to each product (the latter is amore flexible and future-proof option).
Comment: thanks for the quick reply.  So best to add a new category called Taxable, and apply it to all my tax rates and then apply this Taxable category to ALL products that should be taxable.  Is there a way to have this Taxable category selected by default.  99/100 products are taxable so would love to avoid this requirement when added 99% of the products.
Comment: Correct - though no, I don't know of a way to have any categories selected by default when creating new entries.
Comment: RE Store → Settings area, *Match Categories* - should this override country specific tax rates?
Comment: I believe the conditions selected for each tax rate are AND conditions, so no.

Expresso Store No tax option


A SharePoint list that includes "External" colums and SP Native columns

Question: I would like to create a SharePoint list that includes columns from a SQL table (actually, two SQL tables) and columns that are native to SharePoint. Only the SharePoint native columns would need "CRUD" ability. The columns from the SQL Tables would be "read only".
For example, the list would contain:
From SQL Table "Orders": OrderID (PKEY), CustomerID (FKEY), OrderNumber, Qty and Total (all just "read only")
From SQL Table "Customers": CustomerName, CustomerAddress (linked to Orders table with "CustomerID" field). (all just "read only")
Local/Native SP Columns: OrderNotes, CustomerFeedback, DateReturned, DateDelivered (editable by the user)
I seem to have MANY possibilities, from creating my own Assembly that exposes both Tables to definining two or three content types in SP Designer, etc. Generally, we do all of our development in Visual Studio and stay away from SharePoint Designer. Although, I am not opposed to using it in the Prototype stage (it is quicker and I can always create an equivalent VS Assembly and solution that is deploy on the back end...). So, if you have any examples using SPD or VS, please feel free to provide either.
Thanks for any guidance!
Answer: I think only way to do that is create a regular list and have new columns added to this list which are of type "external field"


Baby Girl Stretching

Question: I am a first time mother and I have a 4 month old baby girl. She stretches so severely and intermittently. Could this be normal? What could be the cause?
Comment: When you say _severely_, can you describe it in more detail? Is it extreme extension of all her limbs, is her head bent back? What is her facial expression? Does it tend to be just after waking up, or randomly (unconnected to eating/sleeping/pooping)?
Comment: Everyone stretches. It feels good.
Comment: Thanks every one" Her Paediatrician said today that she is Just and Absolutely Fine'',God bless Our Bundles of Joy!
Comment: Yeah, could you describe in more detail what exactly it is that she does?
Comment: @OloriAdeola - Thanks for adding some information, but there still isn't enough information here to understanding what;s happening. Why do you say "severe". Does she just stretch all four extremities, or does she wiggle around as well? Does she seem otherwise entirely normal? When did this start? How intermittent is "intermittently"? These are important points to shed light on. Add anything that might help.
Comment: Thanks mom, No odd facial expressions ,,head isn't bend nor temperature'' she does it most of the time she needs rapt attention or being angry when I lay her down',like she wants to get up herself and kinda struggling to suit herself"( lol)
Comment: This sounds like a concern you should discuss with your pediatrician. That said, both our daughters did what we called a "peanut stretch" (stretching so far they were bent backwards) and survived the experience.
Answer: If there are no additional worrying behaviors (cries, painful expressions, arc-like bending instead of a straight stretch) I'd say it's normal, it's OK, it's even good, because muscles, apparently, are working as they should.
And it seems so "severe" because we are used to babies lying with their legs bent, curled - a baby stretched, with straight arms and legs, seems somehow unnatural. It isn't, though:)
Answer: It is normal and a good growing sign. As long as your baby is active, happy and feel comfortable then no need to worry. Enjoy!! Baby is learning to use his muscles it seems.

Baby Girl Stretching


Visual Studio 2012 default scrollbars

Question: I've tried to make my Visual Studio more beautyful, so I downloaded Son of Obsidian color scheme from here. And then everething is okay, except scrollbars. Scrollbars are now not Visual Studio 2012 cool custom scrollbars, but Windows default scrollbars. I've tried to resel all preferences using "Import and Export options..." menu, but this won't work. Colors returned to default state, but scrollbars are the same Windows scrollbars. By the way, I'm using Dark theme. So question is how to return normal custom scrollbars back? This default are really very annoying.
Answer: Sounds like you need a clean install if the resets are not working.
To get a clean "Son of Obsidian" or other themes that don't affect scroll bars, go here.
Also see the Visual Studio Color Theme Editor extension for your version of studio that lets you manage your themes.  This should get you back to default theme settings or assist in creating new default theme settings.
After that, you can tweak some hard to find Map Mode Scroll Bar colors in the Visual Studio 2012-13
Tools>options>Environment>FontsAndColors>TextEditor>
Display Items:

Overview background
Overview caret
Overview collapsed region
Overview visible

Visual Studio 2012 default scrollbars


Living in the sukka

Question: Why should one bring the nicest utensils in the Sukka?
Was the first Sukka [in Sukkot] in the midbar not different?
Is the sukka not a dira arai where we should dwell as a remembrance with big simcha and ha-karat ha-tov?
But what does it has to do with the nicest vessels etc [ve-anvehu??]
Comment: Who said they kept Succot in the wilderness? They didn't keep Pesach and they stayed in the Succos all year long.
Answer: The answer is simple, it is learned from תשבו כעין תדורו, see Succah 26.
It means that the Succah becomes the main place and the apartment secondary. So if one has two sets of utensils, he takes the nicest one to the Succah, just as he would do in his main apartment.
As you mentioned this rule is in addition to the rule of זה אלי ואנוהו.
Answer: ''I cant have the entire thing for myself then i don't need it at all ''Does that statement sound familiar A happy and grateful person enjoys his nice dishes and cutlery even when he barely has a roof on top of him OR WHEN ALL HE HAS IS סכך ON TOP OF HIS HEAD.    P.S. THE NICE DISHES SHALL BE THERE BECAUSE OF SIMCHAS YOM TOV OR AS YOUR REGULAR WAY OF LIVING ,AND ON TOP OF THAT HASHEM TELLS US 'ENJOY THIS MEAL IMMENSELY EVEN WITHOUT YOUR REGULAR ROOF TOP' ,WHICH WILL BRING OUT YOUR TRUE SIMCHA ON ZEMAN SIMCHOSAINU .
Comment: Consider clarifying. Are you suggesting that the reason for the halakha regarding one's dishes in the sukkah is to teach the lesson of appreciating whatever one has? Do you have a source, or is this your own idea?
Comment: NO NEED TO SHOUT - we can hear you quite well

Living in the sukka


ZFS under Linux, does it work?

Question: Could I get ZFS to work properly in Linux?
Are there any caveats / limitations?
Answer: ZFS is not in the official Linux kernel, and never will be unless Oracle relicenses the code under something compatible with the GPL.
This incompatibility is disputed. The main arguments in favor of ZFS being allowed on Linux systems revolve around the so-called "arm's length" rule. That rule applies in this case only if ZFS is provided as a separate module from the kernel, the two communicate only through published APIs, and both code bases can function independently of each other. The claim then is that neither code base's license taints the other because neither is a derived work of the other; they are independent, but cooperate. Nevertheless, even under this interpretation, it means the ZFS modules must still be shipped separately from the Linux kernel, which is how we see it being provided today by Ubuntu.
Quite separately from the CDDL vs GPL argument, NetApp claims they own patents on some technology used in ZFS. NetApp settled their lawsuit with Sun after the Oracle buyout, but that settlement doesn't protect any other Linux distributor. (Red Hat, Ubuntu, SuSE...)
As I see it, these are your alternatives:

Use btrfs instead, as it has similar features to ZFS but doesn't have the GPL license conflict and has been in the mainline kernel for testing since 2.6.29 (released in January 2009).
The main problem with btrfs is that it's had a long history of problems with its RAID 5/6 functionality. These problems are being worked out, but each time one of these problems surfaces, it resets the "stability clock."
Another concern is that Red Hat have indicated that the next release of Red Hat Enterprise Linux will not include btrfs.
One of the reasons Red Hat is taking that position on btrfs is that they have a plan to offer similar functionality using a different technology stack they are calling Stratis. Therefore, another option you have is to wait for Stratis to appear, with 1.0 scheduled for the first half of 2018, presumably to coincide with Red Hat Enterprise Linux 8.
Use a different OS for your file server (FreeBSD, say) and use NFS to connect it to your Linux boxes
Use ZFS on FUSE, a userspace implementation, which works neatly around the kernel licensing issue at the expense of a significant amount of performance
Integrate ZFS on Linux after installing the OS.
The license conflict makes distributing the combined system outside your organization legally questionable. I am not a lawyer, but my sense is that, patent issues aside, distributing ZFS on Linux is about as worrisome as distributing non-GPL binary drivers (such as those for certain video cards) with the system. If one of these bothers you, the other should, too.
Switch to Ubuntu, which has been shipping ZFS kernel modules with the OS since 16.04. Canonical believes that it is legally safe to distribute the ZFS kernel module with the OS itself. You would have to decide whether you trust Canonical's opinion; consider also that they may not be willing to indemnify you if a legal issue comes up.
Beware that it is not currently possible to boot from ZFS with Ubuntu without a whole lot of manual hackery.

Incidentally, btrfs is also backed by Oracle, but was started years before the Sun acquisition. I don't believe the two will ever merge, or one be deprecated in favor of the other due to the license conflict and patent issue. ZFS is too popular to go away, but there will continue to be demand for a ZFS alternative.
Comment: Frankly, between ZFS and DTrace, the licensing issue is something that I'm hoping will push more people to consider using FreeBSD.
Comment: btrfs is way less mature than ZFS, which works excellently today, particularly on distributions like Nexenta which, with the Ubuntu/Debian style server-oriented userland, are more usable for those familiar with Linux (IMO).
Comment: *shrug*  My ZFS adventure included a trip into Nexenta land, which I couldn't get running on a perfectly standard new PC I built for the purpose of testing out the ZFS options.  I tried both the stable and the beta versions available at the time.  FreeBSD ran on it just fine, so I went with that.
Comment: @gvkv, rather obscure, server-sysadmin oriented features won't ever win people over to *BSD. Linux is moving forward _fast_ in areas that are relevant across the board: better graphics integration, isolation of processes, virtualization, and lately through [systemd](http://www.freedesktop.org/wiki/Software/systemd) (which depends on Linux-only kernel features) much better management of daemons (and soon integrated handling of desktop environments).
Answer: Several answers here mention the Behlendorf ZFS port.
Keep in mind that the Behlendorf ZFS port is currently targeted towards Lustre users with extremely large filesystems. This is what Lawrence Livermore National Labs, the US Department of Energy and other research facilities need, because they run very large filesystems (100TB - multi-Petabyte systems in the near future). Lustre runs on Linux, and is running into problems when used for filesystems above certain sizes. Some people hope to solve this problem using ZFS, which is where zfsonlinux.org comes into play.
In order for ZFS to be useful for the rest of us, the ZPL (ZFS POSIX Layer) must be ported to Linux, so that administrators can interact with the filesystem. zfsonlinux.org has a development version of the ZPL, and KQ Infotech provides another implementation of the ZPL, which is a fork of the zfsonlinux.org code.
Behlendorf wants help to improve the ZPL and to merge in any changes from KQ Infotech into the zfsonlinux.org repository. If you can do this, the community will benefit greatly, and you will be a rockstar.
Answer: Oh yes, now you can! There is ZFS on Linux Project.
ZFS has been successfully ported to multiple platforms and now there is a a functional Linux ZFS kernel port.

Use Ubuntu + Native ZFS for Linux PPA.
Use RPM-compatible distributive for example CentOS or OLE.
You can compile package by yourself from sources for your Linux distributive.

My real experience is using Ubuntu + Native ZFS - it working very stable from daily repositories.
Answer: I don't know how well they work, but there are two ports of ZFS available for Linux - a FUSE implementation and a in-kernel filesystem implementation.
Answer: You can with the FUSE version of ZFS.  The limitation is that it runs as a userspace process.
Answer: I have set up ZFS Fuse on debian/lenny for my home NAS. I didn't encounter any problems or limitations. Search for ZFS on my blog for some more related posts.
I did try BTRFS first, but found that it simply wasn't ready yet. This was in february 2010.
Answer: ZFS Fuse indeed works.
CAVEAT:  Make sure that the 'other' operating systems you'll use the drive for supports the same version the ZFS Fuse - BSD usually runs a couple of versions later than the Linux ones.

ZFS under Linux, does it work?


Increase vision clarity with eye exercices?

Question: I haven't worn my glasses in a like a year and put them on today. I noticed that vision in one eye is slightly "off" as in, the glasses rated -2.5 power aren't correcting it fully. The difference isn't staggering but it's definitely noticeable. Is it possible to increase the clarity of my vision by wearing my glasses and doing eye exercises so that I can get back to -2.5 power from whatever it's at right now (possible a little more)? I don't have any knowledge of optometry so apologies if this is a blatantly stupid question.
Answer: I've changed eyeglass prescriptions in the past, which is equivalent to what you're doing. Your eyes are no longer currently accustomed to having that kind of lens in front of them, so it feels the same way it did when you put glasses on for the first time.
I would guess that the -2.5 power is the lens which makes a more significant correction to the lens of one of your eyes. I don't remember the numbers for the lenses of my glasses, but my left eye is further off (more nearsighted) than my right eye, so if I were to not wear glasses for a few days, my left eye would notice it more when I put my glasses back on.
I think it was after I had not worn glasses for a while - maybe months - that my vision was evaluated again, and both eyes had changed. My left eye was less nearsighted and my right eye was more nearsighted. So, I would guess that not wearing glasses makes your eyes exercise harder at focusing, which might change the shape of the lenses in either direction.
Maybe after wearing your old glasses for a couple weeks, giving your eyes a chance to get used to them again, if that eye is still not focusing satisfactorily, you should go to the optometrist and have them see if your eyes have changed. (Two weeks is a rough estimate, but I think it's a good amount of time.)
Answer: Exercise is good and that's a right thing to do. But it is impossible to restore vision only by exercise alone. We need comprehensive support of the visual system, special components that affect the eyes. Oculax capsules worked for me. They contain concentrated Lycopene, zinc and vitamins. I took 2 courses of Oculax capsules and my vision was almost restored.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).


Securing php files from external include

Question: Can anybody externally include my php file in their scripts?
E.g. I have a file with classes executing code to db, and is it possible that somebody from external environment includes my php file and is able to run the classes.
Answer: Your PHP files contain scripts that is run on the server side only.
A scenario in which someone could run your PHP scripts on your behalf means either your web application/server is compromised or you have given specific  permissions to a trusted third party for that to happen.
Answer: This might be possible if you allow read-related directory traversal - an attacker might be able to traverse your file system and find the include file.  If he controls your server, then he could drop some PHP code with that include file.
Optionally - remote file inclusion is a variation on the exploit of file-inclusion vulnerabilities by specifying a URL and not a file path. Attacker would need to control your server, find out the name of the include file and upload a PHP script using a FTP service (assuming he discovered or cracked the FTP user password).
For this reason, we do not run FTP services, since FTP passes credentials in plain text, people often leave anonymous FTP open, often use simple passwords etc....


Does the 24 airline ticket cancellation rule allow refunds even after "check in"?

Question: Most tickets have a 24 hour no fee cancellation policy. What if I book a ticket let's say with American Airlines right now (ticket will be say 10 hours from now). I go to the airport, check in, get a boarding pass…find my gate….and then change my mind and do not board the plane. May I get a refund in this case? 24 hours didn't pass. Or does the fact that I "checked in" disallow ticket cancellation?
Comment: Note for future readers, even with the caveats highlighted below, free cancellation within 24 hours of purchase is **NOT** an universal rule. It exists in the US, possibly exists in other countries, but does NOT exist in many other countries (probably most, really).
Answer: The answer will vary depending on the airline, and potentially the country of purchase.
Given your mentioned American Airlines, I'm going to presume you're purchasing the ticket in the US.  The US Department of Transportation requires all carriers to allow you to cancel a ticket within 24 hours of purchase, presuming that the ticket was booked at least 7 days before departure.  Thus as a general rule you couldn't cancel the ticket on the day of flight as you've suggested, as the 24 hour cancel rule wouldn't apply.  (The DOT rules also allow airlines to let you delay payment for 24 hours instead of allowing cancelation, but the 7 day part still applies so it doesn't change the answer)
Some airlines follow the DOT regulations, however some are less strict about the "7 days" requirement.  American Airlines allows free cancelations within 24 hours when the ticket was booked more than 2 days before departure - still too long to allow cancelation after check-in.
United Airlines official policy also requires the ticket to be booked at least 7 days beforehand, however in practice they allow cancelation within 24 hours, regardless of when the ticket is booked.  So in this case it is indeed possible to book a last-minute ticket, and then cancel it right up until the time of departure.  In order to cancel the ticket you will need to be NOT checked in - however it is possible for an agent to "un-check" you in, so it is possible to cancel the ticket even if you have already gone through the check-in process, it just takes an extra step or two.
Answer: https://www.aa.com/i18n/customer-service/faqs/customer-service-faqs.jsp#canceltrip

You have up to 24 hours from the time of ticket purchase for a refund if you booked at least 2 days prior to departure.

So your hypothetical ticket purchased 10 hours ahead was never eligible for a 24-hour refund in the first place, regardless of whether you checked in or not.
In fact, assuming the "2 days" here means "48 hours", then since you can only check in 24 hours ahead, any time that you can check in is already too late to cancel for free.

Does the 24 airline ticket cancellation rule allow refunds even after “check in”?


Install Mac OS X Tiger (PPC) to External HDD with an Intel Mac

Question: I'm running 10.11 on my MacBook Pro and I'm wondering if it is possible to install a PPC OS X to an external HDD using an intel MacBook? Or is there an app that I can use to accomplish this?
Comment: What are you trying to do this on a modern Mac instead of just doing the install on the G5 itself? Seems like there's a missing piece to the puzzle here.
Comment: What model MacBook Pro? No macOS will run on a machine that wasn't invented when the OS was released.
Comment: Macbook Pro 2009. I understand that, I don't want to run the os on the macbook, I want to use the macbook to install the os x to an external hdd that will be used in an old powerpc mac G5.
Answer: You may try your luck with Pacifist. This application will take just the installer packages and extract them to where you want them as a destination.
However, the application falls short in a few areas for a really complete installation, as some things were not designed in: pre- and post-install scripts, blessing (making it bootable), ownership and permission will likely be off.
For these problems there is a nice writeup available at How to install a very small version of OS X on an external drive (2007):

STEP 1: Format your drive (HFS+, journaled)
  STEP 2: Enable owners
 sudo /usr/sbin/vsdbutil -a /Volumes/CRUZER

STEP 3: Install OS X
     Insert disc 1 of your OS X install media (you can close the Finder window that pops up; you don't need it), then open Pacifist and click the "Open Apple Install Packages" button at the bottom. A pop-up window will open that should have an option like, "OS Install - Mac OS X and standard applications (Mac OS X Install Disc 1)":
Selecting an install package to extract from
Highlight it and hit OK. Pacifist will load the relevant files, which will take a little while.Eventually, it will spit out disc 1 and ask for disc 2.
Expand, "Contents of EssentialSystemSoftware", then expand, "EssentialSystemSoftwareGroup" and select both "BaseSystem" and "Essentials":
Selecting the packages to extract
With those two selected, click on File -> Install Files to Other Disk..., select your external drive in the pop-up window and hit OK. In the next pop-up, leave "Use Administrator Privileges" checked and hit "Install", then enter your password to start the process.
During the extraction/copying process, you might see either (or both) of the following warnings:
A file already exists at the following location...
In response to this, check "Don't ask again for this installation", and click, "Leave alone".
The application bundle [path to bundle] already exists...
For this one, check the same box and click "Replace".
Once this process completes you can open up your drive in the Finder and you should be able to see the system folders and files (along with anything else that was already there if you didn't format the partition in step 1):
STEP 4: Copying additional files from your existing installation
Open a Finder window and navigate to /System/Library/CoreServices on
  your main hard drive. Open a second Finder window to the same place,
  but on your external drive. Now copy the file SetupAssistant from the
  former to the latter. (You'll need to enter your password to confirm.)
Similarly, navigate to /Library/Receipts (note: NOT
  /System/Library/Receipts!) on both drives and copy BaseSystem.pkg and
  Essentials.pkg from the former to the latter.
STEP 5: Make the drive bootable
Open Terminal and enter:
sudo bless --verbose --folder "/Volumes/CRUZER/System/Library/CoreServices" --bootinfo --bootefi
(Note the double dashes for each argument in this command! Also, if
  you're using a non-Intel Mac then you don't need the --bootefi flag.)
After being prompted for your password, you should see a verbose
  output for this command, which should contain a number of indications
  of success, e.g. "boot.efi created successfully".
STEP 6: Fix permissions
In Disk Utility, select your external partition and click "Repair
  Permissions". This may take a little while depending on the type of
  drive you're using.
STEP 7: Boot!
Restart your Mac, holding down the option key until you see the list
  of devices that can be booted. If all went well, you should see
  something like this:
Comment: Hi, thank you. Can you give me instructions on how to do this? How do I make the external hdd bootable?
Comment: Thank you so much. I've done all steps, so far so good. But, I'm stuck in step 4, under /Library/Receipts there's a folder named db and file named InstallHistory.plist. Theres no BaseSystem.pkg and Essentials.pkg under /Library/Receipts on my main hdd


Mirror an object feet away from parent object instead right next to it?

Question: How can i get this chunk of geometry to mirror to the other side of the room instead of right next to the object mirroring it?. Also are there any camera settings that would benefit me doing the exterior then working on the interior instead of vice versa?. I ended up pulling up the back wall starting the wood work on that wall then i'm going to pull up a side wall when that's done and start it's wood work i.e trim and inlays etc.because the camera becomes unresponsive otherwise there has to be way to build a structure then work on the guts of it.
Answer: In object mode choose your wall and go into edit mode. Select the front face of your wall and then shifts. Choose Cursor to selected. It will place the 3D cursor at the centre of the face (the front of your wall).

Go back into Object mode and select your door (the pink cube in my case). Right click and select Set Origin > Origin to 3D cursor.

The pivot point of the cube will move to the centre of your wall (front face).
Add a mirror modifier to the cube and set the axis (in my case the Y)

The mirrored cube will mirror across the pivot point.
For your walls if they are planes (single faces) then make sure your normals are facing the interior of the room and turn off backface culling. This means you can work inside your room without the faces (walls getting in the way).
Comment: Thanks man. My  walls though are 8 in thick not planar , I ended up doing this because of additions that connect to the outside walls and they kept poking through, i would delete edges and/or  faces but kept running into one problem or another lol.
Comment: You can select the outer walls and hide them   \ h and alt h to unhide.
Comment: I did that but the camera knows they're still there lol. and gets slow to almost unmovable when it nears even invisible geometry?.


Where is the configuration file of a lxc container?

Question: I installed lxd to use linux containers. For some reason I keep using lxc commands to install and start my containers. Since lxd seems to be close to lxc maybe there is a reason for that (but it is not clear).
I wanted to bind two lxc containers to two different bridges, different from the default lxcbr0 one. I created br1 and br2 and gave them IP addresses. They work fine and are pingable.
I am now trying to locate the place where I should change the configuration of my containers (cont1 and cont2) in order to have their eth0 (the interface name can be kept the same for each of those guests) bound to respectively br1 and br2.
The documentation states that

Then, specify the host's bridge in the container configuration file in
  place of lxcbr0, for instance

Where is this configuration file?
At the top of this documentation page, there is information about configuration files:

The following configuration files are consulted by LXC. For privileged
  use, they are found under /etc/lxc, while for unprivileged use they
  are under ~/.config/lxc.
lxc.conf may optionally specify alternate values for several lxc
  settings, including the lxcpath, the default configuration, cgroups to
  use, a cgroup creation pattern, and storage backend settings for lvm
  and zfs.
default.conf specifies configuration which every newly created
  container should contain. This usually contains at least a network
  section, and, for unprivileged users, an id mapping section
lxc-usernet.conf specifies how unprivileged users may connect their
  containers to the host-owned network.
lxc.conf and default.conf are both under /etc/lxc and
  $HOME/.config/lxc, while lxc-usernet.conf is only host-wide.
By default, containers are located under /var/lib/lxc for the root
  user, and $HOME/.local/share/lxc otherwise. The location can be
  specified for all lxc commands using the "-P|--lxcpath" argument.

If I read it correctly, it does not indicate where the container config file is.
The configuration I would like to add for cont1 is
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = br1
lxc.network.name = eth0
lxc.network.ipv4 = 10.10.11.0/24
lxc.network.ipv4.gateway = 10.10.11.11

and I tried to put it in the files /etc/lxc/cont1/config and /var/lib/lxc/cont1/config but none was taken into account: the container does not start, failing to bring up the networking. It works fine with the default config using lxcbr0.
Answer: A bit late, but in case someone else is - like I was - searching for an answer to this "obvious" question:
The config file for a privileged container seems to be in /var/lib/lxc/${containerName}/config.
Answer: Place configuration file for LXC container in any place and then specify this file when creating a container with -f option:
lxc-create {-n name} [-f config_file] {-t template} [-B backingstore] [-- template-options]

for example:
sudo lxc-create -t download -f /any/path/u1.container.conf -n u1 -- -d ubuntu -r xenial -a amd64


Make reading from PDAs private

Question: If I remember correctly, PDA can be found out by anyone who knows the seed, Public Keys and the Program ID related to a Solana program. Is there a mechanism through which no one except the public key holder (who the account belongs to) has any sort of access to the PDA account? No reading especially?
Answer: As you correctly stated, anyone who knows the seeds can find the address of a PDA.
There is no mechanism to have a private PDA.
You can obfuscate the data instead, e.g. via encryption or some other mechanism, so that only the holder of the public key can make sense of the data
Answer: everything that goes on chain is Public irrespective of who the owner is So in order to make it private you have to implement some sort of encryption and decryption

Make reading from PDAs private


Since, the latest firefox does not have firebug, which version of firefox should i use for firebug?

Question: The latest version of firefox does not have firebug, how can i use firebug even if i have to use older version?
Answer: Yes, for the more current versions Mozilla discarded all classic plug-in APIs of Firefox.
Either you stay with the last version of Firefox 52 (e.g. Firefox 52 ESR portable to be distressed by update requests as less as possible) or you switch over to Waterfox (https://en.wikipedia.org/wiki/Waterfox)!
Waterfox is a Firefox fork which claims to add all new features and fixes of current Firefox versions in the future. Its sole purpose is to maintain support for legacy extensions.
Even if you have a restriction to use explicitly the original Firefox (and stay up-to-date with), you could give Waterfox a try and simply change its user-agent-string to imitate the original Firefox.
Comment: another option would be [*Pale Moon*](https://en.wikipedia.org/wiki/Pale_Moon_(web_browser)).
Comment: I use Pale Moon, but find there are incompatibility issues with some websites. I abhor the newest Firefox, so I'm going to try WaterFox when I get home tonight.
Comment: Thanks for your comment, i will try this.


Equal time commutation relations in canonical quantization of relativistic free fields

Question: Why is equal time commutation relation used in canonical quantization of relativistic free fields? In a relativistic theory, space and time are to be treated on equal footing.
Comment: @RoopamSinha Poincare invariant field theories respect special relativity, not all field theories.  In these theories, it is the invariance of the objects that define the theory under changes of frame that matters.  The idea of treating space and time on the same footing is somewhat vague; would you say that the fact that the $tt$ component of the metric has a different sign than the spatial components is a violation of time and space being treated "on the same footing?"  Time and space are not physically the same, they are simply being considered as two coordinates of a manifold.
Comment: Maybe related to http://physics.stackexchange.com/q/90963/
Comment: I wouldn't say so, Hunter.
Comment: When you say "why," are you asking how we can get away with equal time commutation relations?  Why questions are tricky to interpret.  One answer might be, for example, to note that we do the same thing in quantum mechanics with the operators representing the fundamental degrees of freedom on phase space, and we're just doing the same thing in QFT; it's.  Would an answer of that type be satisfying?
Answer: As a matter of fact one could also discuss commutation relations at different time:
$$[\phi(x),\phi(y)] = i E(x,y) I\quad (1)$$
for free fields $E$ is the so-called causal propagator or advanced minus retarded fundamental solution that depends on the free field equation satisfied by $\phi$.
The point is that, passing to considering interacting fields, at least formally, equal time commutation relations remain unchanged with respect to the free case, whereas the corresponding of (1) changes into an, in practice, unknown form as they include the full dynamics.
Actually even this idea does not work completely, as interacting fields $\Phi$ are affected by a renormalization constant $Z^{1/2}$:
$$\Phi (t,\vec x) \to Z^{1/2} \phi(t, \vec x)\quad \mbox{in weak sense as } t \to \pm \infty$$ and, dealing with naively with renormalization procedure, it arises
$Z=0$. So canonical commutation relations seem to be  untenable for fields $\Phi(x), \partial_t \Phi(y) = \Pi(y)$. However all that sounds a bit academic as the renormalization procedure, in a sense, solves the problem.
I would like to stress that the fact that commutation relations are taken at equal time is not in contradiction with relativistic invariance: Covariance (i.e., the use of tensors and taking space and time on the same footing) is just one way to make explicit relativistic invariance, but it is by no means the unique one!
Hamiltonian formalism is not covariant, though it is relativistically invariant: all equations (including CCR) take the same form in every inertial reference frame.
Answer: Surely, the field and the momentum fail to commute when examined at the same instance, by extension of the logic of quantum mechanics. However, there is no reason why the field and momentum shouldn't commute when they are well-separated in time. Very loosely speaking, they just don't really have anything to do with each other. The logical conclusion is that one should use equal-time commutation relations that denote that the quantities do not commute at equal times but do commute when well-separated in time.
Answer: Let me sketch an answer elaborated in the reference A First Book of Quantum Field Theory by Lahiri and Pal (Second edition, Page $30$).
According to this reference above, the commutator $$[\phi(t,\textbf{x}),\pi(t,\textbf{y})]=i\delta^{(3)}(\textbf{x}-\textbf{y})\tag{1}$$ is actually covariant though the covariance is not manifest!
If two spacetime points coincide in one inertial frame, they will also coincide in different inertial frame. Therefore, at least for the special case when $x=y$ (i.e., $x^0=y^0=t$ and $\textbf{x}=\textbf{y}$), the commutation relation $(1)$ is satisfied in the same form in a different inertial frame.
Now, let us ask whether the relation $(1)$, in general, transforms covariantly under Lorentz transformation. The first thing to note is that $\phi$ is a scalar, and $\pi=\partial_0\phi$. Therefore, the Lorentz transformation property of the LHS comes from $\partial_0$ which makes it clear that LHS must transform like the time component of a four-vector. Now, since $$\int dt\int d^3\textbf{y}\delta^{(3)}(\textbf{x}-\textbf{y})=\int dt\tag{2}$$ and $d^4y=dtd^3\textbf{y}$ is Lorentz invariant, $\delta^{(3)}(\textbf{x}-\textbf{y})$ must also transform like the time component of a four-vector. Therefore, $(1)$ is covariant.
Answer: The field operators are defined in the Heisenberg picture, and the equal-time commutator in the Heisenberg picture is simply the usual commutator in the Schrodinger picture. Hence it is really the same as what we do in ordinary QM!
As you pointed out, the notion of "equal time" is not Lorentz invariant. Indeed, in the canonical quantization procedure, Lorentz invariance of the underlying field theory is obscured because we have to single out the time direction. Yet Lorentz invariance is not lost, although not manifest.
On the other hand, Lorentz invariance is manifest in path integral quantization, which is one of the advantages of this method.


What was the Elder Things' alignment? Good or evil?

Question: What was the alignment of the Elder Things?
Comment: I would wager for [blue and orange morality](http://tvtropes.org/pmwiki/pmwiki.php/Main/BlueAndOrangeMorality) (warning, TV Tropes link).
Comment: Nothing in Lovecraft's worlds were good.
Comment: Lovecraft somewhat addressed this question via Randolph Carter in Through the Gates of the Silver Key, w/regards to the Great Old Ones -  "**He wondered at the vast conceit of those who had babbled of the malignant Ancient Ones, as if They could pause from their everlasting dreams to wreak a wrath on mankind. As well, might a mammoth pause to visit frantic vengeance on an angleworm.**"  (The Good/Evil Great Old Ones/Elder Gods conflict was an attempt at aligning it to Judaeo-Christian views by Derleth - Lovecraft had them transcend such things with regard to humans, as we would to amoebas.)
Comment: When I played 'Call of Cthulhu' in college, we explained it simply -- "**It takes place in a universe that does, indeed, have gods.  But they so transcend anything we can understand, the best you can normally hope for is that they never notice you; things tend to go downhill, if they do.  It's possible that they might help you, but how often do you bother to help gnats/ants/fleas, etc?**"
Answer: That depends largely on which stories you're talking about.
The Elder Things, like most of the other extra-terrestrial creatures in Lovecraft's original stories, can't really be described as "good" or "evil" in the traditional sense. They were alien, so ascribing human motivations to them is somewhat pointless. For the most part, they simply existed on Earth, much like people do now, living their lives.
On the one hand, At The Mountains of Madness claims that the Elder Things were "enemies" of the Great Old Ones. Since the Great Old Ones tended to do things like eat people or drive them insane, we would naturally assume their "enemies" were defending humanity from their evil schemes. But I think that's imposing our ideas of good and evil onto two groups that barely register humanity as worthy of attention. Instead, what we're interpreting as "good" and "evil" is the simply happenstance that the Great Old Ones way of life causes bad things to happen to us and the Elder Things way of life doesn't.
One things that counts strongly against the Elder Things being "good" is their enslavement of the shoggoths. Even after they knew the shoggoths had developed sentience, and desired freedom, they kept them enslaved. On the other hand, this is one of those difficult moral questions that we still haven't got a good answer far, only these days, we ask it about humans and machines instead of Elder Things and shoggoths.
Later, once Derleth took over and started expanding the mythos, he retroactively imposed a more clear-cut distinction. The Elder Gods were a force for "cosmic good" and opposed the Great Old Ones' "cosmic evil", and that was that.
Comment: I think putting The Elder Gods and Great Old Ones into groups of good and bad makes the stories more boring. It makes them too human, which is the exact opposite of what makes H.P. Lovecraft's stories so great.
Comment: I'd liken it to the ants in an ants nest in the middle of No Mans Land between the trenches during world war 1 trying to decide which group of soldiers is on their side or which group want to protect the nest and queen.
Comment: My impression (from god help me growing up around Lovecraft scholars) was that the Great Old Ones were actively hostile towards humanity, while the Elder Gods were indifferent which didn't really make them any better except from our perspective.
Comment: @Broklynite I'm not aware that Lovecraft made that distinction.  It was never clear that Cthulhu was actively hostile, although certainly had a great many ill effects on humanity.
Answer: The question is inapplicable.  The creatures Lovecraft described were generally operating on their own morality and customs, without reference to humanity.  The philosophical basis of much of his work was that humanity couldn't comprehend what was going on in the world.  When encountering things humanity was not meant to understand, humanity in general lost, but that's humanity's weakness instead of hostility from others.
For example, Cthulhu is never described as evil, if you will attribute Cthulhu's eating of some seamen as hunger rather than morals.  Cthulhu being alive caused a wave of nightmares and insanity, but that wasn't Cthulhu's intention.  Human cultists were evil by human standards, but that's part of Cthulhu and the human race being basically incompatible.
Lovecraft didn't divide creatures into Great Old Ones and Elder Gods; that was August Derleth, who made Lovecraft popular, and who didn't understand Lovecraft's thinking (there's a Lovecraft letter somewhere to that effect).  I'd strongly recommend reading the work of S. T. Joshi on these topics.
As far as I know, the first use of "alignment" as you're using it was the original Dungeons & Dragons rules, published in 1974, dividing people and creatures into Lawful, Neutral, and Chaotic.  This system was taken from Michael Moorcock's fictional universe, much as the magic system owes a lot to Jack Vance.  At that time, nobody took D&D seriously in any way, including Gygax and Arneson.  It was just a fun game that was not designed to be anything else.  The Good-Evil axis was added later.  Alignment is not a useful concept for anything outside D&D and things influenced by it.
Comment: D&D did *not* invent the concept of good and evil!
Answer: FWIW, my uncle is a well respected amateur Lovecraft scholar and enthusiast. I passed this question along to him. He was delighted, as he recently presented a paper at the annual Lovecraft Forum, which he describes thusly:

The last paper I presented discussed the distinction between the Elder Gods and the Great Old Ones. Lovecraft was never specific about their attributes or their physical appearances, except in the case of Cthulhu.
Several scholars have speculated that Lovecraft's descriptions of both the Elder Gods and the Great Old Ones anticipated an event in Judao/Christian mythology, when God threw Lucifer and the other rebel angels out of Heaven to reign over Hell.
Others have seen parallels, comparing Great Cthulhu with one of the four major forces of Nature (earth, air, fire, and water). Thus, Yog-Sothoth represents earth, Cthulhu stands for water, Cthugha of the Interstellar Spaces represents air, and a 4th Great Old one (whose name I forget) stands for fire.
One of my colleagues, Ann K. Schwader of Westminster, near Denver, Colorado, whom I regard as the most brilliant poet who ever lived on this planet, reminds me that when Lovecraft discusses geological tectonic mass shifts in At the Mountains of Madness, he is anticipating Science Fiction more than Supernatural Horror. Fans tend to forget what Science Fiction means -- speculatory literature that discusses the literary uses of advancements in science, interstellar travel, contact with sentient species, and dystopian themes describing the end of the world.

So there you have it, make of it what you will. The answer seems to be- depends on your interpretation. As wiggly as that answer seems, remember that the idea was that these creatures were so truly alien that to even try to conceive of them sent one mad because they were so far outside of our everyday reality. If you think that sounds ridiculous, try learning quantum mechanics, and you'll get an idea of how different the world can really be from your everyday reality.
Comment: Do you have a link to the paper he wrote?
Comment: @Ifurini - I was in the middle of doing the exact same edits - well done! It was instilling a sense of unfathomable fear in me that a respected Lovecraftian scholar should have such poor use of basic grammar ;)
Answer: The Elder Things (assuming this refers to the aliens that feature most prominently in At the Mountains of Madness, in which they are referred to as "Old Ones") are by far the most ordinary aliens in H. P. Lovecraft's stories.  They are incredibly tough, but they are made entirely of ordinary matter and are ultimately vulnerable to any kind of concerted mundane attack.  The do not have have powerful psychic abilities and communicate simply using sound.  They do not owe allegiance to any vaster power bent on interplanetary domination.
The Elder Things created life on Earth, but then paid relatively little attention to it, except for their shuggoth minions, their herds if livestock, and any creatures that they deemed strong and vicious enough to be dangerous.  Otherwise, their attitude was largely one of benign neglect.  They were sometimes conscientious about their organic technology and sometimes careless, just as we humans are with our own technological developments.  In fact, the Elder Things are just as fallible or potentially moral as humankind.

They had not been even savages—for what indeed had they done? That awful awakening in the cold of an unknown epoch—perhaps an attack by the furry, frantically barking quadrupeds, and a dazed defence against them and the equally frantic white simians with the queer wrappings and paraphernalia . . . poor Lake, poor Gedney . . . and poor Old Ones! Scientists to the last—what had they done that we would not have done in their place? God, what intelligence and persistence! What a facing of the incredible, just as those carven kinsmen and forbears had faced things only a little less incredible! Radiates, vegetables, monstrosities, star-spawn—whatever they had been, they were men!

The Elder Things are not utterly evil, like Cthulhu and his kin, or even as wicked as the Great Race of Yith.  They are not, as a race, good or evil, any more than humans are intrinsically aligned with one or the other.
Answer: The concept of alignment doesn't really apply to the Cthulhu Mythos, at least as Lovecraft envisioned it. Think about cats. They're carnivores, but when given the opportunity, they don't just kill their prey quickly and then eat it. They play with it, actively drawing out the prey's death for reasons we don't currently understand. But we don't call them evil for this, aside from the occasional Internet joke: they don't have the capacity for understanding right and wrong as we think of them. Their intellect is simply too limited.
The various cosmic entities of the Cthulhu Mythos are similar, but at the opposite end of the scale. Their intellects (except maybe Azathoth's) are too vast and unlimited: they can't conceive of good and evil as we think of them, not because our scales of morality are such large and grand concepts to them, but because they're such small concepts.
It's the same for the Elder Gods and the Great Old Ones. We don't like being around the Great Old Ones, and this is fair because they eat us, but we don't really know what they want other than to not be hungry. The Elder Gods seem more friendly from our perspective, because they don't consider us to be food, but we don't know why they don't consider us food, or anything else that they want, really. Are they good? Are they evil? Perhaps in their own minds, they might be. Or maybe they don't think in those terms at all. We don't have the information, and even if we did, we probably wouldn't be able to understand it.
Comment: FYI, cats are playing with their prey to avoid injury: to kill their prey, cats have to use teeth, which on their flat faces are close to vulnerable eyes (contrary to long-snouted wolves for example). A wounded but alive mice or rat can leash and seriously hurt its captor once the cat brings his face to deliver the kill. But once it is "tortured" to the point of exhaustion, the risk is much lower. Well, either that, or they are simply bastards.
Answer: I could only assume that in rpg alignments elder gods would be true neutral with hints of neutral good, they simply don't care about what's happening and sometimes very rarely they may attempt to help, like how they sealed the great old ones who I think would be neutral evil/chaotic evil.
Answer: Think more simple and purely from the source of Lovecraft's novels and from a point of view of humanity.
Blind idiot god Azatoth is an absolute CHAOS. From one novel all universe is his dream and who cares of his dream? Nobody. So Azatoth is Chaotic Neutral.
Nyarlathotep is the most humanlike of all Lovecraft's pantheon. He tried to cheat Randolph Carter and finally sent him to Azatoth. So from that perspective he is Chaotic Evil.
Other gods, such as Shub-Niggurath, don't care of humanity. But they obviously don't respect people's laws at all. So they are Chaotic Neutral.
Yog-Sothoth from the other side symbolizes "all in one", "the clue", "the gate", " future and past"... - some sort of order which humanity can't comprehend. He (or she) also don't care about humanity, but some cultists can try to use him for their evil plots. Yog-Sothoth' name is also called by cultists in protective spells. But the Universe (Cosmos), which is symbolized by Yog-Sothoth is an anthonim of Chaos, so I think, Yog-Sothoth is Lawful Neutral.
Comment: Is this your own opinion or can you offer any textual evidence to back up these bold assertions?


Can't find Wifi Direct option in settings

Question: I have Sony Live with Walkman mobile phone, Android version 4.0.4.
I can't find WiFi direct option in settings. There are only mobile networks, tethering/portable hotspot and two more useless options are there.
Comment: Not a direct answer to your problem, but I find [Gesture Search](https://play.google.com/store/apps/details?id=com.google.android.apps.gesturesearch) invaluable in finding hidden settings that aren't where I expect to find them.
Comment: NO, it didn't helped but I thinks that probably the wifi Direct also depends on hardware configurations
Comment: Is it dependent on hardware support?
Answer: Actually there isn't any option like that. Its missing. There were lots of complaints about 4.0.4 Update for Live with Walkman that Wifi Direct is missing.
look at here.
Also look at this review of update..:
First of all thanks for the wonderful update and congratulations.
Few things i would like to share with sony:
1. We cannot uninstall Appextra from the phone at all and should have that option
2. Phone dialer is laggy it takes almost 3-5 sec to open the dialer plz fix that
3. really time to update the kernel to 3.0 as i have ssen the ICS running on kernel 3.0 with same hardware specification as Xperia 2011 portfolio has and the phone runs better than it is currently running on 184.108.40.206-pref version
4. Wifi Direct option is missing as its a feature of ICS 4.0.X fix that in next update so that we get that option as well
5. please provide us option to move some of the internal app to sd card as it will save more space on phone memory.
6. when tried to update the inbuilt application such as liveware manger Error Unable to do that it says "An existing package by the same name with a conflicting signature is already installed.
7. Google talk application sometimes says we are offline even though we are not.
8.live wallpaper gets force close all of a sudden many times.
9.screen shot option is complicated and should be in the same way as it was in GB
10.photos when viewed from xperia gallery should provide more detail info for the photos and videos as it shows in galary app.
11. A normal sound recorder application should be their to record voices or conversation
12. A file manger application should be their.

May be sony will fix it in next update.
Answer: Try going onto your wifi settings page. When your on the list of available connections there may be a button at the bottom of the screen titled "Wifi Direct".
..That's how it is on my S3 anyway
Comment: How does that answer the OP's question, the OP clearly stated *I can't find WiFi direct option in settings* plus, also stated *Android version 4.0.4*...
Comment: No there is no such button anywhere as I mentioned but I found the button in one of my friend's samsung galaxy tablet which has same version of android(4.0.4). as of mine.
Comment: The older versions of android has it in 'more settings'.. since the update my phone has moved it to the wifi settings. I know plenty of people who are unaware of where it moved too and I had to direct them! I missed the bit where he stated the Android version..

Sorry for trying to help 't0mm13'...


(VW CC 2010 2.0L Sport) How do you diagnose a parasitic battery drain from a fuse that controls rear window raisers and central locking system?

Question: My 2010 VW CC is having a parasitic drain issue and I've isolated the problem to one of the fuses which is for the rear window raisers and for the central locking system. If I keep this fuse out overnight, I can start my car but if I leave it in and lock my car, it drains within a couple of hours and I have to jump my car. The problem with leaving this fuse out and calling it a day is that you're unable to lock the car.
How do I begin to troubleshoot this issue?
Where exactly is the "central locking system"?
Answer: You start by isolating each component connected to that fuse / circuit and finding out which one is causing the drain.
A process of elimination and it helps if you approach this logically ie disconnect all and reconnect one component at a time.


If the input of the system depends on the future outputs then is the system non-causal?

Question: While I'm aware of the fact that causality implies that the present output is only dependent on present and past inputs, something that is bugging me is what if the input is dependent on future outputs. Would the system be causal or anti-causal in that case? I look at this with the assumption that since input depends on the future outputs, then in that case, the outputs only ever depend on the past and present inputs and thus should be causal. I would love some insight into this. Take, for example:
$x[n]=y[n-1]-2.5y[n]+y[n+1]$
where $x[n]$ & $y[n]$ are inputs and outputs of an LTI system, respectively.
Answer: The equation
$$x[n]=y[n-1]-\frac52y[n]+y[n+1]\tag{1}$$
is just a way of representing the input-output relation of a linear time-invariant discrete-time system. It does not mean that the input depends on the output. The input is always given and the system behaves in such a way that the output satisfies $(1)$.
Note that from $(1)$ we cannot determine whether or not the corresponding system is causal. You could rewrite $(1)$ as
$$y[n+1]=x[n]-y[n-1]+\frac52y[n]\tag{2}$$
which would suggest that the system is causal, because it seems that the output at time $n+1$ only depends on past values of the input and output. However, we could also rewrite $(1)$ as
$$y[n-1]=x[n]+\frac52y[n]-y[n+1]\tag{3}$$
which would suggest that the output only depends on future values of the input and output. Finally, another way of rewriting $(1)$ is
$$y[n]=\frac25\big(y[n-1]+y[n+1]-x[n]\big)\tag{4}$$
which seems to imply that the output depends on current, past and future values.
From the difference equation $(1)$ we simply cannot tell if the system is causal or not. Eq. $(1)$ represents three different systems, as expressed by Eqs $(2)$, $(3)$ and $(4)$: one causal, one acausal (left-sided), and one non-causal (two-sided). In order to completely describe the system, we generally need more information than just the difference equation.


Showing that a basis spans the exterior product space $\bigwedge^k(V)$

Question: Suppose I choose $\{e_{i_1}\wedge e_{i_2}\wedge\cdots\wedge e_{i_k}:i_1 < \cdots <i_k \}$ to be my basis for the exterior product space $\bigwedge^k(V)$  where $\{e_1, \cdots, e_n\}$ is the standard basis for the vector space $V$.  I would like to prove that this is a basis.  Linear independence is easy, but spanning seems like a massive undertaking.  Suppose I take any arbitrary vector $v_1 \wedge v_2 \wedge \cdots \wedge v_k$ in my exterior product space, and I wish to express this vector in terms of the basis elements above.  It seems like I have a massive chain of sums and products to deal with here.  Is there any way to simplify the computations?  How would you do this?
Comment: The element $v_1 \wedge v_2 \wedge \cdots \wedge v_k$ isn't an arbitrary $k$-vector.  An arbitrary $k$-vector would be a sum of $k$-vectors of this form (what you have is called a $k$-blade).
Comment: If you already know what the basis is for the $k$-fold tensor product, you can use the image of that basis under the quotient map into the exterior algebra as a spanning set of $\bigwedge^k(V)$. Then it should be pretty easy to see the candidate basis you have above is indeed a basis of the exterior product.
Answer: As a comment above said, not every $v \in \bigwedge^kV$ can be written in the form $v_1 \wedge v_2 \wedge \cdots \wedge v_k$.  However, every vector can be written as a linear combination of vectors of this form. It therefore suffices to show that every $v$ of that form (i.e. every $k$-blade) can be expressed as a linear combination of your basis.
With that, suppose that $v_j = \sum_{i=1}^n \alpha_{ij} e_i$.  We can then write
$$
v_1 \wedge \cdots \wedge v_k =
\left(\sum_{i_1=1}^n \alpha_{i_11}e_i\right) \wedge \cdots \wedge \left(\sum_{i_k=1}^n \alpha_{i_kk}e_i\right)
$$
By multilinearity, expand this into
$$
\sum_{1 \leq i_1,\dots,i_k \leq n} \alpha_{i_11}\cdots\alpha_{i_kk}(e_{i_1} \wedge \cdots \wedge e_{i_k})
$$
Now, using the alternating property of the wedge product, why is this ultimately a linear combination of your basis vectors?
Comment: I struggle with your statement "However, every vector can be written as a linear combination of vectors of this form". How do we know that to be true?
Comment: @Azur This essentially comes down to the definition of the exterior product.


Mann-Kendall trend test

Question: I'm trying to find some information about the Mann-Kendall trend test. I've tried to make some research on google but the main reference that I find is the 1976 book "Rank correlation methods" by Kendall. Obviously this book isn't easy to find so I hope that you could give some links to find some practical information about it
Answer: It's also known just as the Mann test.  I find it in Nonparametric Statistical Methods, Hollander and Wolfe, and a discussion of its power in
The Power of Statistical Tests for Trend Detection.  It's in the R package Kendall.
Hopefully, this will be enough to get you going.

Mann-Kendall trend test


Anaconda installation modifying .bash_profile on Mac OS X

Question: I installed Anaconda on my Mac (Mojave) and now whenever I start a shell it automatically activates the conda environment. This was totally fine until I realized some of the commands in my .bashrc were not being executed on startup. In particular, I had increased HISTSIZE and HISTFILESIZE but they always seemed to be stuck at their default values of 500. After some googling, I learnt that because of my anaconda installation, it was my .bash_profile that was being used on startup and not .bashrc. This is what my .bash_profile looks like (see below), just adding commands from my .bashrc file (e.g., HISTFILESIZE=100000) to the top of my .bash_profile appears to do nothing. Any suggestions on what I am doing wrong? Thanks!
<code># Setting PATH for Python 3.7
# The original version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/3.7/bin:${PATH}"
export PATH
# added by Anaconda3 2019.07 installer
# >>> conda init >>>
# !! Contents within this block are managed by 'conda init' !!
__conda_setup="$(CONDA_REPORT_ERRORS=false '/anaconda3/bin/conda' shell.bash hook 2> /dev/null)"
if [ $? -eq 0 ]; then
    \eval "$__conda_setup"
else
    if [ -f "/anaconda3/etc/profile.d/conda.sh" ]; then
# . "/anaconda3/etc/profile.d/conda.sh"  # commented out by conda initialize
        CONDA_CHANGEPS1=false conda activate base
    else
        \export PATH="/anaconda3/bin:$PATH"
    fi
fi
unset __conda_setup
# <<< conda init <<<

# >>> conda initialize >>>
# !! Contents within this block are managed by 'conda init' !!
__conda_setup="$('//anaconda3/bin/conda' 'shell.bash' 'hook' 2> /dev/null)"
if [ $? -eq 0 ]; then
    eval "$__conda_setup"
else
    if [ -f "//anaconda3/etc/profile.d/conda.sh" ]; then
        . "//anaconda3/etc/profile.d/conda.sh"
    else
        export PATH="//anaconda3/bin:$PATH"
    fi
fi
unset __conda_setup
# <<< conda initialize <<<
</code>
Answer: You can try to add the following lines in the bash_profile as suggested Here:
<code>if [ -f ~/.bashrc ]; then
    source ~/.bashrc
fi
</code>


How to protect Authentication API from a DDoS attacks?

Question: After Login, severs can check authorization, tokens etc at API and WAF levels to mitigate DDoS attacks. But this can only happen after user has logged in. How can we protect DDoS attack on login API? I guess we can use ip address as one of the hint to detect attack, but what are other options available? Thanks!
Answer: I second @RaimondsLiepiņš; don't try to solve DDoS yourself, buy protection through your CDN.
At its core, a DDoS attack comes down to whether the attacker has a bigger firehose than you do; if they can use a botnet to generate more requests-per-second than your server can handle, then they win.
CDNs have invested in AI, monitoring, security teams, etc to detect sudden spikes of traffic and respond to them in real-time using a variety of tricks to filter legitimate traffic from bot-generated traffic. I totally recommend paying your CDN for DDoS protection rather than trying to invent it yourself.
Comment: Mike and Raimonds, Thanks for your suggestions. I understand using CDN DDoS protection is a better way to mitigate. But from academic perspective, I wish to understand how authentication API can be protected from DDoS attacks. I do know few techniques post authentication, but without any user data how a resource can be protected must be extremely tricky.
Comment: @Vijayendra DDoS is not a very academic thing. It's essentially just "lots of people wanting stuff from you", and the only way to answer this is to have more ressources than the attacker. It's a simple "might is right" scenario and nothing more.
Comment: @Vijayendra Correct, very tricky. You need some sort of artificial intelligence to try to detect which login requests are legitimate, and which are part of an attack. `fail2ban` is software you can install on your server that does an ok job at this. In general though, CDNs are in a better position to do this because they can analyze traffic across their entire network looking for suspicious patterns, whereas you can only see traffic at your server.
Comment: Anti-DDoS is a hard problem. Don't expect good results unless you have a team of humans watching realtime traffic analysis on monitors and reacting.
Answer: Just use a CDN to deliver the webiste, that will be the best protection against a Distributed DOS attack.


Fastest way to join mysql 4.0 data from multiple tables?

Question: I have 3 mysql 4.0 tables: all have fields ID(int), type(int) and another field, value which is either varchar(255), tinyint or int.
I need to write them all out and I end up getting three DataTables, looping over them, and creating rows into a temporary table (in .NET 1.1).
Do you see any faster/cleaner way than this to join or just write out this data?
Answer: I am not sure if you are wanting to actually join or display the results from all three tables in one query.
If you are just wanting flat out results, your best best would be to do a union such as:
<code>SELECT
    ID,
    Type,
    Convert(varchar(255), Value) as Value
FROM
    table1
UNION
SELECT
    ID,
    Type,
    Convert(varchar(255), Value) as Value
FROM
    table2
UNION
SELECT
    ID,
    Type,
    Convert(varchar(255), Value) as Value
FROM
    table3
</code>
Note: I am doing the convert so that you can get the most stable form (the varchar version) of all three of your fields.
Comment: Thanks, actually it worked even without converting, but i'm worried because instead of 420 results I'm only getting 410 this way - maybe some are duplicates and are merged?
Comment: @Spikolynn: it may be possible that the an implicit conversion is occuring in your ints and tiny ints (or your varchars are trying to convert to ints) and when it fails conversion it is getting dropped from the result set.
Comment: TheTXI: I tried with Convert(Value, char) instead of Value all three times, but it still shows not enough results. I don't mind much though, because the app should work the same if they are just duplicates as I presume.
Comment: yup, i checked for duplicates today and they were exactly as many as the missed records count. maybe i should add a unique constraint over the three fields
Comment: oh, and I had to use convert, because otherwise I would get an .NET exception about incompatible column types :S


Does the air of the car fan come from outside air or inside air?

Question: Does the air of the fan in the interior of the car comes from outside air or is it the same air that circulate inside, when the air conditioner is off and heat is also off (just the fan) ? or is it an option available in all vehicles to choose between the 2 options ?
Comment: There is usually a [button](https://i.stack.imgur.com/CWEkn.jpg) to select between 'exterior air' and 'recirculated air'. Some a/c settings will set it automatically. The 'default' is external air, as people do not want to breathe stale air, which will also mist up the interior glass very readily. In most vehicles I have driven, when the vehicle is moving, the 'ram' effect is enough to introduce fresh air even when the fan is off.
Comment: Welcome to Motor Vehicle Maintenance & Repair! I removed the image you had provided because it is a copyrighted image from 123rf.com
Answer: By default most cars have an outside air inlet which supplies fresh air to the passenger compartment.  There is usually a control on the HVAC panel that allows you to select air recirculation which closes the outside air inlet and just reuses the existing air.
Usually you won't want to do this for very long as moisture quickly accumulates and will fog your windows.
Comment: Here in the US, even if set to "recirculate," some outside air is allowed to enter the passenger compartment. I'll bet it's the same in other countries.
Comment: This may be an OSHA ( or ??? ) rule . Bring in outside air to flush any possible exhaust gas leak into the passenger area.
Comment: @blacksmith37 on my previous Mk I Octavia, the air source would automatically change to 'recirculate' when put in reverse gear, presumably so that driving back though the exhaust gases would not allow them to enter the cabin. I have always wondered why the exhaust of cars is at ground level, though: in traffic the exhaust from the car in front comes straight in.
Comment: Yes @ David... , that is what I was trying to say . And very likely likely the manufacturers use the same heat/AC plenum for all countries.