Should I trust Teamviewer?

Question: One of my colleagues asked me to install TeamViewer so he can help me at work. Should I trust TeamViewer? I mean, will they be able to spy on me?
Do I have full control of what they see of my computer and when?
Comment: The app is deployed as an installer and adds a service that runs in the context of SYSTEM. Does that answer your question ?
Comment: Unless someone from Teamviewer is willing to answer, we cannot know. This makes it opinion based which is off-topic here.
Comment: I'd also like to know if they are able to install any programs like keyloggers without my permission?
Comment: @Stephane It doesn't have to be like that. There is an flavor known as TeamViewerQS (QS = quick support) which works like a portable app. It's an exe file which you download and start. It will even work without any priviledges. So at least you can be (quite) sure that once you stopped and possibly deleted this executable again, you don't keep a permanent back door in your system.
Comment: @TorstenS Additionally, on Linux you can simply start and stop the teamviewer daemon on demand (`teamviewer daemon [start|stop]`).
Answer: We cannot know what Teamviewer does with your data but there are some security risks you should watch out for:

Don't share your private details on a public screen. Some people use Teamviewer to get to screens that are placed far away or high up off the ground (advertising boards and etc) which are available to the public to see. If the Teamviewer details are displayed any user can login to that PC.
After using it renew the private code or uninstall it if not needed anymore so no one can login with the same code again.

If you really do not trust it you can try other programs such as standard RDP.
You can also read a little more about the Teamviewer connection in this question.

Should I trust Teamviewer?


How to make a video game with emacs?

Question: If I wanted to make a video game with emacs what are my options? Are there frameworks? What graphics capabilities does emacs have? Can I make 3D first person shooters with emacs?
Answer: First of all, Emacs is a text editor.  Teaching it other tricks is a neat pastime (I engage in it all the time), but I've learned to lower my expectations.  I know of a single framework attempt (which the author scrapped for standalone implementation in CL) or maybe even two if the built-in grid.el counts (it's the basis behind M-x tetris, M-x snake, M-x pong, etc.).  3D games rely on graphical acceleration, typically solved with OpenGL, DirectX or whatever the favored low-level solution to leverage your GPU is.  Emacs doesn't have FFI and even with the upcoming module support this kind of thing is possible, but far from on the same level of convenience as SDL or comparable solutions.  You could alternatively write a software rasterizer, but I doubt this will have comparable speeds unless you restrict yourself to wireframe rendering maybe.
Regarding the graphical abilities, the display engine allows you to display images.  Most games go for tiling by generating many square-sized images and moving them around, others generate a single one, place it in a suitable location and update.  Puzzle games can get away with updating on user input, anything more advanced will need to build its own game loop hosted on top of Emacs editing loop.  It's tricky to do this in a speedy manner, but I've succeeded in doing so for a XPM Tetris.  SVG allows you more freedom ultimately, so that's where my future demos will go.  For further details, check out my Quasiconf 2015 talk.
tl;dr: You can make games, it's not a walk in the park, a 3D FPS is currently out of the question.
Answer: Did you see Multiplayer 3D walk on Emacs?
It's just amazing !

3D maze by Emacs (Multiplayer)
kiwanami/emacs-3d-demo · GitHub
Emacs 3D Multiplayer FPS (in Japanese)
3D maze by Emacs (single player)
Multi-player 3D FSP on Emacs | Hacker News

The author kiwanami says, drawing graphics and numerical calculation in Emacs is so much slower compared to Java.
He is joking "about 1,000 times slower." ;)
Answer: Short: Is it text? Emacs can do it. Is it a 3D GUI that allows you to place objects in a scene? You are looking for a scene editor. Scene editors are not text editors or IDEs. They are a completely different application altogether. You can program any game imaginable in Emacs, but you will likely need other tools besides a code editor to perform the other tasks needed to complete a game.
Long: I professionally use Emacs to program games which utilize the Crytek, Unity, and Unreal game engines, among other engines. Game programming using a programming language is just text editing, which is something Emacs excels at. However, when it comes to placing objects in a scene, rotating them, animating them, etc., this is typically done in specialized applications. This separation of applications is not peculiar to Emacs, this is how game programming is done in general on all OS and development platforms. Visual Studio does not support scene management either. Indeed, I am not aware of any major IDE that supports scene management, though some scene managers have built-in code editors. However they are usually feature poor compared to a dedicated code editor or IDE.
I suggest you read about the applications and libraries professional game programmers use. I personally prefer:

Blender (3D modeling and animation)
Emacs (text and code editing)
engine-specific scene editor (example: Unity and Unreal editors)
lots of software libraries so I don't have to reinvent the wheel
a GPU debugger, such as apitrace

How to make a video game with emacs?


E-commerce for wordpress

Question: Is there an e-commerce solution for wordpress which will allow a shop with an onsite blog?
If so, what are the options and is there generally one thats considered the 'best'?
Answer: I highly recommend WooCommerce. Those guys are brilliant. It's based off of Jigoshop another great solution. To me, though, WC is one of, if not, the best solutions for WP e-commerce. Great support. Great themes. Uber easy to integrate with a custom theme as well.
Comment: +1 for WooCommerce. Easily one of the best free e-commerce plugins available for Wordpress at this point in time.
Answer: Try WP-eCommerce, it's quite supported and has themes designed around it!
Answer: I've had great luck with Ecwid, although for most cart owners it will be a paid solution.  It delivers everything via a CDN, which helps load time - on the down side, it uses very heavy javascript, which may slow things down on WordPress.  The biggest reason I went with it on a particular project is the store is managed in a separate backend from the site, meaning the production and shipping guys can still do their job without mucking about with permissions in WordPress.
I would most definitely NOT use WP-eCommerce, as every time I've worked with it I've spent more time attempting to debug or fix it than actually using it.  It's not supported (unless you're willing to pay for support), and they will charge you to fix their own sloppy coding errors.  Until they rewrite it from the ground up, avoid it like the plague that it is.
Also, as The Z Man recommends, WooCommerce is definitely awesome.
Answer: I can definitely recommend WooCommerce as it's pretty solid and getting more and more theme support outside of just WooThemes. Have also used WP-eCommerce but didn't have as much trouble as others have indicated. Everything like this is always case-by-case anyway, depending on your specific needs. The Shopp plugin is also worth a shot and seems to be pretty intuitive based on the little time I've played with it.
Answer: WooCommerce, Cart66, Jigoshop. All great plugins each with their own pro's/con's
Whichever Wordpress E-Commerce platform/plugin you use, make sure you are PCI Compliant (something many site owners are ignorant of).
All of these plugins will allow you to use either Paypal or some gateway's hosted checkout page which places you in compliance but weakens the brand and discomforts the potential buyer (something you don't want to do right before they're about to give you their money). You can go the Paypal route, implement the PCI standards yourself (read: $$$), or use a hosted checkout page that offloads the PCI compliance. Check out this article about the complexities of PCI Compliance. Here's a snippet explaining the levels of PCI Compliance:

Even if your website does not store credit card data, if it transmits credit card data you need to complete the Self-Assessment Questionnaire C (SAQ C) in order to be compliant.

Credit card companies and merchants are cracking down on PCI non-compliance and the penalties are hefty. Here's the list of requirements on the PCI Security Standards website.
All that said, I would go with WooCommerce or Cart66 with their baked in Mijireh integration so that you can have a hosted checkout page (read: PCI Compliant) and have it look like your site (read: brand recognition and customer comfort).

E-commerce for wordpress


How to disable the lost network connection warning on OSX

Question: I'd like to permanently disable the warning dialog that shows when my Macbook loses connection to a network drive.  Is this possible in OSX Mavericks?
Answer: From this article: http://whatsamknows.tumblr.com/post/37368603810/get-rid-of-server-connections-interrupted
The following steps should sort you out:

Click on the spotlight icon (magnifying glass) in the upper right of your screen
Type in 'terminal'
Click the 'Terminal' icon (black with white border) under
applications
Type in the following command and hit enter:
sudo mv /System/Library/LoginPlugins/FSDisconnect.loginPlugin /System
It will prompt you for your user password. Type it and hit enter again
Reboot


Tool to bulk remove Facebook status updates

Question: Is there any tool/webapp out there that will let me bulk delete past status updates?
The only solution I have found so far is going back manually and deleting them one by one.
Answer: Yes, there is a program called iMacros that allows you to automate any browser based task, such as deleting status updates. Here's one I found to delete your facebook statuses: http://www.cynthiaperla.com/facebook/460/how-to-delete-all-groups-and-wall-posts-from-facebook-using-imacros.html
Comment: Great tip! If all else fails atleast I can clean it all out. Im looking for some more detailed control over what to remove though but this is by far better information then I got from googling for an hour before asking the question :)
Comment: Seems like this solution is outdated now. Any updates?
Answer: There is the userscript Absterge

Absterge works such that a user logs in to the Facebook Timeline, and navigates to the 'Activity Log' section. The removal process automatically unrolls all user's activity (by triggering click to "More Activity" link), and then removes every activity that can be removed from the logs. The only required user's activity so far is to expand the year where the logs are chronologically classified. The script deletes everything.

Install Firefox (any OS on any architecture)
Install Greasemonkey (https://addons.mozilla.org/en-US/firefox/addon/...)
Download and install the Absterge script available above.
Log in to Facebook and make sure that Facebook Timeline is available.
Navigate to the 'Activity Log'.
The script will start unrolling the current expanded year triggering the 'More Activity' click event.
As soon as the script finds posts / comments / status updates, those will be automatically removed, without warnings.
In order to remove the activity of another year, just expand the year tab. The script will take care of the rest.
Comment: Why? What makes this userscript so suitable to the task?
Answer: There is a python script that is open source that will do much of this for you - at the very least it can remove old statuses and pictures.
https://github.com/chander/social-network-cleaner


Word ordering for "so" as conjunction

Question:
Today is warm, so we will go outside.

Which of the following word order is correct?

(a) Heute ist es warm, so gehen wir raus.
(b) Heute ist es warm, so wir gehen raus.
Answer: As already pointed out, "also" is the correct word to use here. In this case, since "also" is a conjunctional adverb (I don't actually know, whether it would be called this way in English, the correct German term is "Konjunktionaladverb"), the correct word order is "also - verb - subject". This applies also to all other words of similar type like "dennoch", "doch", "ebenso" or "insofern" (and many more).
But let me add some other uses of "so" that were not mentioned already. You can use the German "so" in the sense of the English "if" - in very formal circumstances:

So Gott will, wird es gut gehen.

If God wants, it'll be alright.
Another usage that you might frequently encounter is in the sense of "like" as a filling word in colloquial language:

Er sagte so: "Hau ab" und ich so: "Nein"

He said "Get lost" and I answered "No" (feel free to add "like": He said like, "Get lost"...)
Comment: An idiomatic translation of *Er sagte so: Hau ab* and *und ich so: Nein* would be *And he's like: f___ off!* and *And I'm like: No!*.
Answer: In German I don't believe you can use so as a conjunction, but rather also, which fills the 1st position in the sentence or clause sending the subject to the 3rd position.

Heute ist es warm, also gehen wir aus.

contrasted with

Heute ist es warm, und wir gehen aus.
Comment: Verb is still in 2nd position, as clause+`also` only fill up one position together.
Answer: You only use so when you comparing people or things:
Ich bin so alt wie du
I am as old as you (are)

Du bist größer als er

You are taller than he (is)
It can also meansuch or like that:

Schau mich nicht so an!

Dont look at me like that!

So ist das Leben.

That's the life.
In this context, so is not used here but also instead:
Heute ist es warm,also gehen wir aus.

Word ordering for "so" as conjunction


Was Muhsin Ibn Ali (Radhi'allahu'anhu) a grandson of our beloved Prophet Muhammad (SAW), according to authentic Sunni sources?

Question: I tried to search online but I was not able to find answers. I want to know if our beloved Prophet Muhammad (Sallallahu'alayhiwassalam) had a third grandson whose name was Muhsin Ibn Ali (Radhi'allahu'anhu), according to authentic Sunni sources. Is Muhsin Ibn Ali (Radhi'allahu'anhu) considered a grandson of our beloved Prophet Muhammad (Sallallahu'alayhiwassalam) by Sunnis?
Comment: Well the [Arabic wikipedia site on Fatimah](https://ar.wikipedia.org/wiki/%D9%81%D8%A7%D8%B7%D9%85%D8%A9_%D8%A7%D9%84%D8%B2%D9%87%D8%B1%D8%A7%D8%A1#%D8%A3%D8%A8%D9%86%D8%A7%D8%A4%D9%87%D8%A7) actually clearly confirms this for both shi'a and sunnis (المحسن بن علي) See also [Muhsin ibn 'Ali](https://en.wikipedia.org/wiki/Muhsin_ibn_Ali).
Answer: Imam ad-Dhahbi quoted in his short biography of Fatimah bint Rassuli Allah () فاطمة بنت رسول الله  -in Siiyar a'laam an-Nubalaa' سير أعلام النبلاء  the following:
In the following I'm translating from Arabic language. As these translations are of my own take them with the necessary care.

وقال ابن عبد البر : دخل بها بعد وقعة أحد . فولدت له الحسن ، والحسين ، ومحسنا ، وأم كلثوم ، وزينب .
Ibn Abd al-Barr said: Her -with 'Ali- marriage was consumed after the incident of Uhud. She bore him Hassan, Hussein, Mohsen, Umm Kulthum, and Zainab.

Ibn Kathir quoted in his history al-Bidyah wa an-Nihayah (Volume 7) البداية والنهاية the following:

قال الإمام أحمد: حدثنا حجاج، ثنا إسرائيل، عن أبي إسحاق، عن هانئ بن هانئ، عن علي قال: لما ولد الحسن جاء رسول الله صلى الله عليه وسلم فقال: « أروني ابني، ما سميتموه؟ »
Imam Ahmad said: Hajjaj infomred us, Israel informed us, on the authority of Abu Ishaq, on the authority of Haani' Bin Haani', on the authority of 'Ali who said:
When Al-Hassan was born, the Messenger of God, may God's prayers and peace be upon him, came and said: «Show me my son, what you called him? »
فقلت: سميته حربا.
فقال: « بل هو حسن ».
I said: I called it him Harb (war).
He said: "Rather, he is Hassan (good)."
فلما ولد الحسين قال: « أروني ابني، ما سميتموه؟ »
فقلت: سميته حربا.
قال: « بل هو حسين ».
When Al-Hussein was born, he said: "Show me my son. What did you call him? »
I said: I called him Harb (war).
He said, "Rather, he is Hussein."
لما ولد الثالث، جاء النبي صلى الله عليه وسلم فقال: « أروني ابني، ما سميتموه؟ »
فقلت: حربا.
فقال: « بل هو محسن، ثم قال: إني سميتهم اسم ولد هارون شبر وشبير ومشبر »
When the third was born, the Prophet, may God bless him and grant him peace, came and said: «Show me my son, what did you name? »
So I said: Harb (war).
He said: "Rather, he is a Mohsin, then he said: I named them -like- the name of Aaron's son, Shabar, Shabeer and Mushabir."

He further quoted that ibn Sa'ad mentioned the same narration with a different narrator chain starting with a statement of 'Ali (), but he didn't mention "When the third was born":

قال علي: كنت رجلا أحب الحرب، فلما ولد الحسن هممت أن أسميه حربا، فذكر الحديث بنحو ما تقدم،
Ali said: I was a man who loved war. When Al-Hassan was born, I wanted to call him war, and he mentioned the hadith in the aforementioned manner.

See also in As-Sunan al-Kubra of imam al-Bayhaqi Hadith #12148 here or #11594 here, and in imam Ahmad's al-Musnad #3706.
Ibn Kathir also add:

فأول زوجة تزوجها علي رضي الله عنه فاطمة بنت رسول الله صلى الله عليه وسلم، بنى بها بعد وقعة بدر، فولدت له الحسن وحسينا ويقال: ومحسنا ومات وهو صغير.
The first wife 'Ali, may Allah be pleased with him, married was Fatima, the daughter of the Messenger of Allah, may God bless him and grant him peace. He consummated it after the battle of Badr, and she bore him Hassan and Hussayn, and it is said: And Muhssin who died when he was young.
وولدت له زينب الكبرى، وأم كلثوم، وهذه تزوج بها عمر بن الخطاب كما تقدم.
And she bore him Zaynab al-Kubra and Umm Kulthum, and this was married to Umar ibn al-Khattab, as mentioned earlier.
ولم يتزوج علي على فاطمة حتى توفيت بعد رسول الله صلى الله عليه وسلم بستة أشهر.
Ali did not marry another wife (beside) Fatima until she died six months after the Messenger of Allah, may Allah bless him and grant him peace.

Some articles say that this son might have been a death birth.
Comment: Thanks for answer.
Answer: The children whose mother is Hazrat Fatemeh (PBUH) (the daughter of the Messenger of God (PBUH)), including Imam Hassan (AS) and Imam Hussein (AS) and Mohsen and Zeinab Kobra and Umm Kulthum Kobra. Mohsen had an abortion during the attack on the house of Hazrat Zahra (PBUH). Ibn Athir says: Mohsen died as a child. Zainab married Abdullah ibn Ja'far ibn Abi Talib and Umm Kulthum became the wife of Umar ibn al-Khattab. But the views of the Sunnis are as follows Hazrat Zahra (PBUH) was the only survivor of the Messenger of God (PBUH) whose sweet life ended after her death. There was no sweet time in the life of that lady.
Because the pressures, wars and conspiracies of the enemies on the head of Islam and the Holy Prophet (PBUH) constantly disturbed the peace of the soul of Fatima (PBUH). But with the demise of the Holy Prophet (PBUH) new storms of complex and critical events began to blow, the grudges of Badr, Khyber and Hanin, which were hidden under the ashes in the time of the Holy Prophet (PBUH), became apparent. For this reason, he went to the grave of the Holy Prophet (PBUH) and felt sorry for him: Dear father! After you, I was alone and alone, I was amazed and lost, my voice turned to silence, and my back broke and the refreshing water of life became bitter in my mouth. And it was always the case that 75 days or 95 days had not passed since the death of the Holy Prophet (PBUH) who joined his noble father due to the sufferings he saw, and therefore it can be said that the martyrdom of that great lady is an undeniable truth and one of the certainties of Islamic history. So that no one can work, because Shiite and Sunni historians and narrators have described it in spite of various pressures and statements, and here are some of them. Of course, it should be acknowledged that the meaning of the martyrdom of Fatemeh Zahra (PBUH) is that she suffered after the death of the Holy Prophet (PBUH) in suffering, pain, oppression and cruelty by the enemies of the Ahl al-Bayt (AS). Eventually, it led to the martyrdom of that Imam.
Ibn Qutaybah Dinuri writes: The same day that Abu Bakr learned from some people who had disobeyed allegiance to him and had gathered with Ali (AS). So he sent Omar to those who had gathered in Ali's house. So they refused to leave the house, at which time Omar ordered you to bring firewood. Addressing the people of the house, he said: I swear to the one in whose hands Omar's life must be taken out, otherwise I will set the house on fire with his family. What Fatima is at home. In the same source, he mentions that after a few days, Abu Bakr told Umar to go to Fatemeh Zahra (PBUH) because we had made her angry. They went to Fatemeh Zahra (PBUH) together, but Fatimah allowed them to enter. He did not, but they entered the house through the mediation of Ali (AS), but Hazrat Fatemeh Zahra (AS) did not speak to them. Shahrestani quotes from another book of the system: On the day of the people's allegiance to Abu Bakr, who was in charge of this matter and Omar was ordered to take allegiance from Ali and those who were in his house! He shouted loudly to set fire to Ali's house and he himself hit Fatemeh Zahra (PBUH) on the abdomen so much that Fatemeh threw her fetus from her abdomen. Ibn Hajar also quotes Muhammad ibn Hammad Kufi in his book that he believes that Umar undoubtedly kicked the belly of Hazrat Fatemeh Zahra (PBUH) and this led to the abortion of Fatemeh Zahra (PBUH) whose name is Mohsen Ibn Ali Was led. It can be seen that although some Sunni scholars have refrained from recounting this true piece of history in order to preserve the position of the caliphs and have considered it as a Shiite belief and thought, nevertheless a large number of Sunni scholars have not been able to They cover up the reality, even though they did not narrate the whole incident and only mentioned it briefly.
In this regard, Seyyed Morteza quotes that at the beginning of the work, narrators and historians did not refrain from quoting the disrespect that entered the field of the daughter of the Holy Prophet of Islam (PBUH). It was well-known among them that the caliph's agent pressed the door on Fatemeh Zahra (PBUH) and she aborted the child she was in the womb, and Qanfaz, under the command of Umar, whipped Fatemeh Zahra (PBUH) so that she He took it from Ali, but later they saw that the narration of these matters was not compatible with the position of the caliphs, so they refused to narrate them. Muqatil Ibn Atiyah says: Abu Bakr, after taking allegiance from the people with threats, fear and swords, sent Umar, Qanfiz and a group to the door of Fatima and Ali. Set on fire. When Fatemeh Zahra (PBUH) came from behind, Omar and her companions gathered and Omar pushed Hazrat Fatemeh Zahra (PBUH) behind the door so much that she aborted her child and a nail went into the chest of Hazrat (PBUH) (and as a result of those injuries He became ill and fell into bed until he died.
Another Sunni scholar, who is a Shafi'i, quotes a person named Ibn Dram al-Muhaddith as saying that Omar definitely kicked Fatemeh Zahra (peace be upon her) and had an abortion as a result of Mohsen's blow to her abdomen. This is a beautiful example given by this Sunni scholar ::: Ibn Abi al-Hadid al-Mu'tazili narrates: Abu al-'As, the husband of Zainab, the daughter of the Holy Prophet (PBUH), was taken prisoner by the Muslims during the war, but was later released like other captives. Abu al-'As promised the Holy Prophet (PBUH) that after returning to Mecca, he would send Zainab to Medina with the Holy Prophet (PBUH), so he sent several people to wait for Zainab near Mecca and accompany her to Medina. Upon learning of the departure of the daughter of the Holy Prophet (PBUH), a group decided to bring her back halfway, so when they attacked Kajaveh Zainab, Zainab was frightened and had an abortion and returned to Mecca. The Holy Prophet (PBUH) was very upset to hear this news and considered the blood of the murderer of Zainab's son permissible in the conquest of Mecca. Ibn Abi Al-Hadid says: I called this process to my teacher Abu Ja'far Naqib. (SA) was frightened that caused his son to have an abortion "Mohsen", he must have considered it permissible.
Abu Ja'far says with conviction that if the Holy Prophet (PBUH) witnessed the sufferings that were inflicted on his dear daughter, he would consider the blood of the perpetrators permissible. It was mentioned. Safavid narrates another Sunni scholar that on the day of allegiance, Fatemeh Zahra (PBUH) was really beaten to death that Mohsen had an abortion and after that Fatemeh Zahra (PBUH) passed away. -Skuni, who is one of the narrators of Sunni and reliable hadith, quotes in the news that I had a daughter and I was upset about this case. I went to Imam Sadegh (AS), told him the story and he asked what did you name your daughter? I said: Fatima, she said: Oh, oh, then she put her hand on her forehead and seemed to be crying. Is Sukuni says that Imam Sadegh (AS) was always like this, when the name of Fatima was mentioned in front of Hazrat, he remembered his grandfather and remembered her calamities and always reminded him and said: the cause of death and martyrdom Fatemeh Zahra (PBUH) was a blow inflicted on her by Qanfiz, a slave. Although Sakuni quotes the words of the Imam so far and does not mention the rest of the words of the Imam due to Sunni prejudice, but Abu Basir states that the cause of death of Fatemeh Zahra (PBUH) was the blows that Gholam Omar's hemp with a sheath of sword on that Imam. Omar ordered, so he lost his son Mohsen and became very ill and did not allow any of his abusers to come to see him.
Therefore, considering that the Sunni scholars, although in the first centuries, referred to the events after the death of the Holy Prophet (PBUH) and the story of the martyrdom of Hazrat Fatemeh Zahra (PBUH), but later, in order to preserve the position of the caliphs, they refused to mention them. The existence of reports in Sunni sources can be well known in the story of the martyrdom of Hazrat Fatemeh Zahra (PBUH) and the perpetrators.


Brother DCP-1510: How to reset toner cartridge

Question: My printer (Type: Brother DCP-1510) reports that the toner is empty and refuses to print. However, the last pages printed were perfect. How can I convince it that everything's all right?
Answer: I just managed to fix it. The issue is the 'Replace Toner' message appeared on the screen and won't allow any prints. Below is the solution:

Press Menu button: Options will appear, press ok for the option 1. General Setup
Go down by the arrow key to option 4. Replace Toner and Press OK
Use Arrow Key UP or Down and you will see option (Replace Toner Continue) and press OK.
Do not select option (Replace Toner Stop).

This will fix the issue and you can print with the low toner until you get a replacement toner sorted.
Trust this helps.
Asim Hashmi
Lancashire, UK
Answer: I found good instructions here (in Dutch):

Press the menu-button,
Use the arrows to browse to "machine info", press OK,
Use the arrows to browse to "reset drum",
Press and hold OK until the display shows

^  reset
v  empty

Instead of using any of these options, press Start,
Immediately after that, repeatedly press the arrow up (^) until the display shows the number 10,
Immediately after that, press OK; the display should say "Accepted",
Press Stop to exit the menu.
To be sure, switch the printer off and on.

After step 4, you may instead get the message "Printer is busy". Switching the printer off and on worked for me.
Steps 5-7 may also fail, I suspect that this happens when you are too slow.


Using fancyhdr to handle headers of different sizes

Question: I want to use fancyhdr in the letter document class to define a custom header for the first page only. I know that I can use \fancypagestyle to do this (as is discussed here), but the problem is that my first-page header contains several rows, and I don't want the following pages to contain white space at the top that results from the 'missing' header. Is there a fix for this?
Comment: You can use `\thispagestyle` command and a separate header for that. Also, change the `headheight` accordingly using `geometry`.
Answer: I wanted specific margins in my front-page, and following code helped me to specify margins for only that page. After \begin{titlepage} I put:
\usepackage[paper=a4paper]{geometry}
...
\pagestyle{empty}
\newgeometry{top=1in,bottom=1in,right=1in,left=1in}


is schwa a phoneme in English?

Question: or is it simply an unstressed allophone of unstressed lax vowels? I'm curious because I've heard some people claim that [ə] is not a phoneme and it is just a reduced allophone of all the unstressed vowels in English.
Comment: If you consider **ʌ** to be a phoneme when stressed, then, yes, you can use schwa for unstressed vowel allophones. Although quite frequently it's [ɨ] and not [ə] that's the unstressed allophone, especially with high vowels. But the simplest structure is simply to say that caret is the stressed allophone, and all the other central vowels are unstressed allophones. There's a lot of room there in the center of the vowel space, and no contrasts.
Comment: The commA and happY phonemes are different phonemes: there are minimal pairs such as enemas/enemies, commas/Commies, Rosa's/roses, sofas/Sophie's. That's enough to justify commA as a phoneme.
Comment: A trivial case, perhaps, but I can offer one instance of schwa contrasting with caret.  I noticed a while ago that even in the upper strata of BBC radio, (a) 'gonna' is acceptable for 'going to' and (b) schwa *can* be stressed.  Imagine the case of young man who joins the Royal Artillery because his father and uncles did.  "With his background, he was always *gonna* be a Gunner."    /hiː wəz ˈɔːlwɪz ˈgənə biː ə ˈgʌnə/
Comment: @RosieF You mention roses as a word from the happY set. That's a very odd choice since, in quite a few accents (like my American one), the unstressed vowels in those two words are hardly alike.
Answer: First, "allophone" is the wrong term to use for many-to-one mappings between phonemes and surface realizations. Allophonic rules are not neutralizing, so final devoicing in German (for example) is not an allophonic rule. Aspiration in Engilsh is, because only /t/ becomes [tʰ].
Second, just to be clear, we say that the voiceless alveolar stop in English is the phoneme /t/ and not the phoneme /tʰ/ because the rule deriving [tʰ] from /t/ is simpler than the converse rule deriving [t] from /tʰ/. Or, so it has been thought – but it turns out that if you state the rule in terms of stress-foot position ("deaspirate foot-medially") you not only can state deaspiration as easily as you can state aspiration – plus, you can also explain why /h/ deletes in words like "prohibition". So the analogous question is, is it easier to derive [ʌ] from /ə/, or is it easier to derive [ə] from /ʌ/? There is no difference in simplicity: you get schwa when unstressed and caret when stressed. So it seems to be a coin toss.
But third: lots of (unstressed) vowels become schwa in English, as one can see from alternation like monotone ~ monotony [ˈmɔnətoʊn, məˈnɔtəni] though in some dialects, my [ɔ] is [a]; telegraph ! telegraphy [ˈtɛləgræf, təlɛgrəfi]. There is a many-to-one mapping between all sorts of vowels and schwa: so this is not an allophonic relation. Not all rule-governed relations in phonology are allophonic.
The conclusion therefore would be that every instance of schwa in English can be derived from some other vowels when unstressed. Sometimes you can tell that it comes from /ɪ/ or /ɛ/ given stress alternations as in telephone ~ telephonic. Sometimes you cannot tell: the first and last syllables of vanilla, first syllables of collapse, giraffe. The decision to say that the first vowel of vanilla must be underlyingly some vowel other than schwa is based on an unsupported claim that English underlyingly has no instances of schwa. That vowel could be ɪ, or ʌ, or ɛ, or æ...
The motivation for purging schwa from underlying forms is the idea that there is an intolerable acquisition burden to learning 12 phonemes compared to 11 phonemes. However, the rationale is countered by the heavier burden on acquisition that comes from having to make an arbitrary decision regarding the underlying form of many words. Whereas, if the default assumption is that the underlying form is the same as the surface form unless there is good evidence saying otherwise (and "saves a phoneme" is not good enough evidence), then schwa can be a phoneme of English, meaning that it is present in underlying forms.
Answer: It is not an allophone for sure. An allophone must be associated with a single phoneme; [ə] isn't, it's associated with multiple phonemes.
You might want to consider it as a phoneme or not, but that depends on a bunch of factors, like:

Are phonemes "real"? They might be as well just a convenient abstraction¹. If phonemes are not real, it's up to the author to decide to include or exclude /ə/ as its own phoneme.
If however phonemes are real, how do speakers interpret [ə]? Do they associate it with other vowels, or do they treat it as a unit of its own?²

Personally speaking I do not think that speakers keep track of "phonemes", but of articulations and how they contrast with each other. As such, I wouldn't analyse [ə] as belonging to its own phoneme; it's simply easier to analyse it as a fully unstressed realisation of other vowels.
And, even when you don't know which vowel that [ə] is "supposed" to be associated with, for me it's just for convenience, so might as well assign it a random value like /ɪ/ or /ʌ/ depending on the dialect in question³. The net result will be the same, call it a chicken or a duck, in that position it's simply a "bird".

See Is the very concept of the phoneme disputed? for further discussion.
Harder to analyse than it looks like. Not only different people will give you different answers, but the spelling itself will interfere on the data quite a bit.
/ɪ/ for NZE, /ʌ/ for GA.

is schwa a phoneme in English?


Can we write bridge smart contract using ink?

Question: I was reading about ink smart contracts and was curious is it possible to make bridge using ink, as there is already parity-common-bridges present. It would be very helpful if someone knows about this or can point to any documentation for the same.
Answer: I'm not sure if I understand correctly what you mean with "to make bridge using ink!", so I'll try to answer what I guess you mean.
So in the Substrate universe you would build a bridge to another chain as a Substrate runtime module and not as a smart contract. Those are two different things in Substrate. parity-common-bridges is a collection of Substrate modules (those are called "pallets" in Substrate terminology) to build a bridge.
Substrate has a number of other pallets, one of them is called pallet-contracts. It's a module that you can add to your Substrate runtime to give it smart contract capabilities. With ink! you can write smart contracts for this pallet-contracts.
Not every chain needs smart contracts, on Polkadot/Kusama many actually don't have a need for smart contracts because they realize this functionality purely within their Substrate runtime. For example, some chains don't have a need for users to execute programs which make use of the chain business logic (which is one reason why a chain would want to add smart contract capabilities).
I suspect that your questions stems from a confusion that people learning about Substrate often run into: that most things are implemented as a Substrate runtime and not as a smart contract.
There is a great answer to Smart Contracts vs. Runtimes on Substrate here: When should I build a Substrate Runtime Module versus a Substrate Smart Contract?.


Was "Verily, I say unto you" (Matthew 8:10) a phrase unique to Jesus, or was it taken from the Rabbis? What was the original source of this phrase?

Question: Was this phrase one that Jesus coined to emphasize His authority, or did He adopt it from the rabbinical schools?  Was it a common phrase by the Greek orators, or the Roman poets?
Answer: The phrase as quoted in Greek was more literally Amen, I tell you (ἀμὴν λέγω ὑμῖν), which in Aramaic would have been close to what is in the Syriac Peshitta:

ܐܝܡܝܢ ܐܢܐ ܐܢܐ ܐܡܪ ܠܟܘܢ
amen ana ana amar lakhun

Literally:  Amen, I [I again repeated for emphasis] say to you.
The same phrase appears around 75 times in the New Testament.  In the Gospel of John, Jesus is even more emphatic:  ἀμὴν ἀμὴν λέγω ὑμῖν - Amen, Amen I say unto you (25 times).

The use of "Amen" as a statement of affirmation would have been common among Jewish rabbis during the time of Jesus.* "Amen" is a Hebrew word (אָמֵן) that means "so be it," "verily," or "truly." Rabbis would use this term to affirm the truth of a statement or teaching.
However, Jesus' use of ἀμὴν λέγω ὑμῖν  or ἀμὴν ἀμὴν λέγω ὑμῖν was distinct in that he used it to preface his own teachings, emphasizing their importance and authority. In contrast, rabbis of the time would typically use "Amen" after making a statement or quoting Scripture to affirm the truth of what had just been said. The way Jesus used these phrases set his teachings apart, highlighting their significance and demonstrating his authority as a teacher.  This usage was among what annoyed the Pharisees about Jesus.

* See, e.g., R.E. Brown, R. E., The Gospel According to John (I-XII) in The Anchor Yale Bible
Comment: + 1 and thanks.... but I'd add rabbinical writings were not [preserved until two centuries later](https://en.wikipedia.org/wiki/Tannaim).  So we can't be certain that they accurately reflect the usage of Jesus' time.
Comment: @DanFefferman, I'm thinking that the Jewish writings are likely to be more accurate than what the critics are saying. For example, according to the Mishna, it was the Jewish custom in the first century to memorize a Rabbi's teaching as a ritual of sorts. It was taught that a good pupil was like a "plastered cistern that loses not a drop." (Mishna Aboth, II.8.)

That being said, the specific examples that R.E. Brown brings out from the Jewish tradition would be helpful to improve this post.
Comment: @Jess I too lean toward the idea that the Mishna reflects 1st cent. usage... I merely point out that this is not certain.
Answer: "Amen" is a Hebrew word spoken to affirm the truth or veracity of what is being said.  See Appendix below. It occurs 30 times in the OT, most often in Doxologies.
Many parts of the NT were written in a Bible-soaked culture of Jewry; thus it is unsurprising that "Amen" and many other Hebrew words appear in the NT.
However, "Amen, I say to you" is unique to Jesus and must be regarded as one His personal mannerisms or characteristics of His speech.  Jesus is the only person to use this word at the beginning of a statement to show His personal authority.  [Elsewhere it only occurs at the conclusion of what is said.]
APPENDIX - BDB entry for אָמֵן Amen

אָמֵן adverb verily, truly Deuteronomy 27:15,26 (12 t.) 1 Kings 1:36;
Nehemiah 5:13; Jeremiah 11:5; Jeremiah 28:6 & doxologies 1 Chronicles
16:36 ( = Psalm 106:48); אָמֵן (ו) אָמֵן Numbers 5:22 (P) Nehemiah
8:6, & in the doxologies Psalm 41:14; Psalm 72:19; Psalm 8:9Psalm 48.
ἀμήν = Amen: אֱלֹהֵי אָמֵן Isaiah 65:16 (twice in verse) God of Amen
De Che RVm; compare Revelation 3:14, or God of faithfulness, God of
truth (RV) (perhaps read אֹמֶן Che Di).

Note that the phrase cannot have come from Greek sources because it employs a transliterated Hebrew word, "Amen" which would not have been used by either orators or Greek writers.  It is decidedly Hebrew and appears about 30 times in the OT.
However, it might have come from the Jewish Rabbis but we have no record of this.
Answer: Various books state that there is no other parallel to this phrase, the word was used at the end of a curse or something for emphasis. Moulton's Grammar of NT Greek states that though it has no rabbinic literature parallel, it was well established among the Jews.
It is noteworthy, that this idiomatic phrase by Jesus makes it hard to defend the doctrine that Jesus' teachings were sarcastic or satirical, and should not be taken at face value to be obeyed. John 8:34 "Jesus answered them, "Truly, truly, I say to you, everyone who commits sin is the slave of sin".


How to identify a low proportion cell subpopulation in the single-cell RNA-seq data?

Question: The cell subpopulation that I am interested in only accounts for around 1.2% of the total cells. I have previous FACS experiments that sort out the subpopulation from the samples (using markers CD166+ CD49fhi CD104- Lin-, see images). May I ask if there are any ways to identify this cell population from single-cell RNA-seq data of the tumor epithelial samples using the marker information?
Answer: Run the usual steps including clustering and visualization via something like UMAP and then color the UMAP by these four markers. That assumes that the surface marker separation you see in flow holds true on a transcriptional level which is not necessarily the case. For example, hematopoietic surface-defined populations such as the Granulocyte-Macrophage Progenitor (GMP) are well-separated in flow but on transcriptional single-cell cell level span many clusters.
Alternatively, check the tool UCell which can calculate a score per cell based on a combination of positive and negative markers. You can then color the UMAP by this to see whether a single cluster stands out or whether this celltype contributes to many clusters ir is not even present at all. Include some marker combinations that you know are oresent and some nonsense combination that must be absent to have positive and negative controls. That will give you a feel whether that score for your cells is reliable.
This all assumes that the cells are even in the dataset. Depending on cell size and frequency (underrepresentation) they might even have dropped out during library prep.


What is the position of HD Heads during a spin down?

Question: So I'm debating between powering down and sleep mode when toting my macbook around in my backpack.  Apple says the HD 'spins down' when in sleep, which obviously means is not spinning.  But are the read/write heads completely removed from the platters as in power down or still poised at the last read/write position?
If they aren't cleared of the disc, I'm not dragging it around in sleep mode.
Comment: FWIW I've been toting MBPros (all accelerator-enabled models) around in sleep mode for years now with zero issues. Close lid, go.
Answer: The heads are parked out of the way. See http://en.wikipedia.org/wiki/Hard_disk_drive#Landing_zones_and_load.2Funload_technology, specifically:

Modern HDDs prevent power interruptions or other malfunctions from landing its heads in the data zone by either physically moving (parking) the heads to a special landing zone on the platters that is not used for data storage, or by physically locking the heads in a suspended (unloaded) position raised off the platters.
Comment: That does lead me to believe it's parked during sleep, and certainly during power-down, but it seems to be talking specifically about emergency situations (power failure, drop detected).
"During normal operation heads in HDDs fly above the data recorded on the disks." So is sleep more like 'normal operation' or more like power-down?
Comment: When you put it (the macbook) to sleep it'll switch off all non-essential things so as to conserve power, including the hard drives. So they'll be parked.
Answer: In a modern hard drive, the heads are suspended above the platters by airflow. If the heads were over the data areas while the platters are not spinning, then they would touch and possibly cause damage. Therefore, hard drives must move the heads away from the data when not spinning.


Search - Two Buttons

Question: I'm working on a site that needs to have the ability to search News (within the portal) and the entire web. This is an option that my colleague came up with. It doesn't seem right to have two buttons that initiate a search. I've seen radio buttons as an alternative, but does anyone have a better option?
Answer: Two of most common search patterns can do the job.
Comment: I love the second pattern (the one with tabs) - it shows both areas available to search in (these are not hidden in a dropdown as in first pattern) needs one less click, and user can click the other tab when he/she can already see the results from the first tab are not satisfactory.
Answer: How about having two radio buttons and a command button ?

Google has a different way to do the same (For searching images, maps, videos etc)
Answer: If you can afford it computationally, search on both and let the user decide after they've looked at the documents which ones are useful. You can rank everything together & let the user scroll through it, and you can add faceted filtering for those who know what they want to see.
Answer: Keep the task simple. Main activity is searching the news, so the bar should only have the 'Search' button and a proper label 'Search News'. Search the web is an additional functionality, use a checkbox to allow the user to enable or not-enable the functionality.

download bmml source – Wireframes created with Balsamiq Mockups
Amazon does similar thing with it's review's search
Comment: @JasonKing You change the functionality. Edited answer.
Comment: In this case the primary is actually to search the News contained on this particular site.
Answer: You can have a larger textbox which is prominent on the display area of your page, which will search the content inside your web pages/system. Then you may use a search box on the top right corner which will be used to search the contents on Google.
Another option you may think of is using a drop down, which in case may not be that convenient or user friendly.
Answer: First, there is confusing button label Search News. How could user guess that News means portal search? Even on screenshots in answers you can see label In Web News.
Second, your option with two buttons is good enough. At least, it is clear for user where to perform search (after correcting label Search News).
Third, if task analysis and/or web server logs show you primary search source (i.e. 70% refer to Web), than you could do radio buttons with smart default, as was shown earlier.
Answer: Although your example is not a common pattern or convention, it is perfectly clear and concise (the radio button and drop down list alternatives are not as concise and require more work, both cognitively work and mouse-clicking).
I don't see any better alternative to your example.

Search - Two Buttons


Bitcoin.conf "blocksdir" parameter not taking effect?

Question: I am running Bitcoin core on a raspberry pi with an external ssd. I am using this line in the bitcoin.conf to move block storage onto the ssd: blocksdir=/media/bitcoinstorage/.bitcoin/blocks
However, when I run bitcoind, blocks still get written to the default location at ~/.bitcoin/blocks
This is what I've tried so far:
Running with these flags:
bitcoind -conf=path/to/conf -blockdir=/media/bitcoinstorage/.bitcoin/blocks

Precreating the .bitcoin/blocks directories in the desired location.
Setting permissions on both directories involved (media and bitcoinstorage) to 777 to no avail. The default permissions for using /media required sudo - I don't know much about how permissions work and if they're inherited so I'm guessing this might have something to do with it.
Each time in between I have deleted the .bitcoin directory entirely and done bitcoin-cli stop before trying again. It seems like no matter what I do I cannot change the default blocks storage location.
Any help would be appreciated here. Thanks :)
Answer: There is a typo in your flag. It reads blockdir but it should be blocksdir.


Prevent deactivation of wireless upon wired connection

Question: I have a Raspberry Pi Model B, running Raspbian Wheezy, with an attached (and fully functional) Ourlink USB wireless card. However, upon making a wired Ethernet connection, the wireless network is disconnected. Is there any setting I can change to prevent this? I have verified that both wireless and wired connections can function simultaneously, by manually re-enabling the wireless connection over the wired connection.
Comment: It shouldn't do... Could you post the output of things like `ipconfig` and `iwconfig` and `netstat -rn` after connecting the ethernet, so we can help you work out what happened?
Answer: In the /etc/network/interfaces file, change the line
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

with
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Explenation is that wpa-roaming is a method with which you can browse and connect to wireless networks.
The result of the following setup is that if an ethernet cable is not attached, wlan0 takes precedence and connects you to your desired wireless network or to an available open wireless network or a predetermined wireless network. If you connect an ethernet cable, the cabled network connection immediately shuts down WiFi access and eth0 then connects you to the cabled network. By unplugging the network cable the wireless connection will instantly be available again.
Source : http://manual.aptosid.com/en/inet-setup-en.htm
I assume that, wpa-conf is the static configuration which not needed for roaming through network interfaces. I couldn't find any relevant and detailed document for this.


Is it a good idea to mention to the USA immigration officer that I'm visiting my girlfriend?

Question: I spent 5 months in the USA, and everything went without a problem. Now I'm spending my second month back in my country (the Czech Republic). In a week or two I want to go back to the USA for another 5 months, visiting my girlfriend who is studying there and is a US citizen.
Is it a good idea to mention to the immigration officer that I'm visiting my girlfriend, and that's basically my travel plan? I have a regular traveler visa.
Comment: It's never a good idea to mention anything that's not explicitly asked.
Comment: @JakubKohout *How else I'm supposed to spend time with my girlfriend?* By getting **married** and applying for an applicable spousal visa.  The USA does not support girlfriends or boyfriends, but it does support wives and husbands.
Comment: @JakubKohout "How else I'm supposed to spend time with my girlfriend?" - unfortunatly, immigration services don't really care about that. They've no duty or requirement to fascillitate international relationships. Also, most people don't spend most of a year simply following their girlfriend/boyfriend around. There is going to be suspicion that you are working or similar.
Comment: Jakub, what visa (if any) did you use to stay in the US for five months?  The standard Visa Waiver Program would only allow you to stay 90 days at a time, so you may already have overstayed.
Comment: Just wondering, what *are* you planning on doing in those 5 months during the day while your girlfriend is busy studying? That's the nub of the problem. If you've got a clear explanation, that's probably fine, else most people would assume, "Well, he's not going to sit in the house all day, probably he's going to get a job". Also, friendly tip, if your username is your real name, it wouldn't hurt to change it ;-) probably not *necessary*, but there's no point making life riskier if you *do* follow the "half-truth" option
Comment: Staying for 5 months + another 5 months has a (very) good chance of raising a red flag. The immigration officer may suspect that you are moving your center of life there. There is also the question how you cover your cost of living if you are in the US for 10 months per year without a work permission.
Comment: @gerrit With the caveat that they also watch out for [marriage scams](http://www.alllaw.com/articles/nolo/us-immigration/proving-bona-fide-marriage.html) designed merely to get you into the country and then dissolve the marriage.
Comment: "Regular travel visa": Is that a B1/B2?
Comment: @GalacticCowboy Right.  So they'll do good to prepare some evidence that they've known each other for a while.
Comment: It can't be stressed enough - be honest from the very beginning. I was in a similar situation when I was visiting my future wife in US. I got called aside and spent 1.5-2 hours waiting and answering all sorts of questions. All this because I said that I am going to visit my girlfriend. I believe that I convinced them that I have a job back in my country (I had some technical notebooks with me) and they let me through. That was not a pleasant experience at all. They tried to kick me off balance but I remained calm the best I could and answered every question as it is.
Comment: @fkraiem Sure. And the very first question you're asked (not counting, "How are you?", which is American for "Hello!" and isn't a real question) is "What is the purpose of your visit?" You've now been explicitly asked the question to which the answer is, "I'm visiting my girlfriend."
Comment: thank you. also do you think that the immigration officer could have a problem letting me in, when I'm planning to stay there again 5 months?
Comment: I'm going to go with two months of rent in my bank and my family is going to send me more money during the staying there. I'm not planning on moving there I just want to visit my girlfriend during the semester. How else I'm supposed to spend time with my girlfriend?
Comment: My business partner just came in through NY from India to see his girlfriend. He said when he told this to the agent, he gave him a big smile and waived him through.
Comment: @JakubKohout How did it go? I am in same situation as you are right now, however, I was on my first visit on Visa Waiver with 90 days. Also CZ citizen, but residency in UK.
Answer: I was in a similar situation a few years ago. I actually sent an email to US Customs & Border Protection. Their response back then was that they would expect me to be outside of the US for about an equal amount of time to what I had just spent inside before returning.
In my case, I had been in the USA with a visa waiver (as a EU citizen) for 82 days (almost the full 90 days). I stayed home for 90 days and returned.
I was pulled from the line at the airport immigration before making it to the front. I was taken to a separate room and asked a lot of questions along the lines why I was returning again on a tourist visa, whom I was going to stay with, how I was going to pay for all this, etc.
I was allowed to enter the country because I could answer all those questions to their satisfaction. But in this case, immigration was very serious about the matter.

screenshot of the email-exchange:

the important paragraph reads:

The Visa Waiver Program doesn't work that way. If he decides to use the Visa Waiver Program (ESTA); maximum stay is 90 days and he needs to allow adequate time between visits. The rule of thumb is if he is in the US for 90 days; should be out of the U.S. for 91 days before returning.
Comment: @D_Bester: The U.S. always knows who you are before you arrive. So do many other countries. You and the airline are required to provide documentation in advance (the APIS program, brought in in 2006). So all they'd need to do is see that Joe Bloggs was inbound and that he'd been in country for 90 days within the past (say) 180 and say "Hmmm, we'd better check this guy out."
Comment: They "pulled [you] from the line". That means they were waiting for you i.e. you were on a list of people they thought might violate the law. Did you identify yourself in the email? Maybe just the dates of previous travel triggered extra questions. Dunno.
Comment: I have heard this "equal time" thing before many a times but I thought it urban legend because the official site explicitly states there is no set time between visits. Care to share a screenshot of this email? I think it'd be super popular.
Comment: Note that the rules of thumb here is exactly that -- a rule of thumb. You're not allowed to use VWP to live in the US and, if you start making long visits on VWP, with short gaps between them, they'll class that as trying to live in the US. How long the stays can be an how short the gaps can be is up to the CBP officer's interpretation of your situation. If you try to stay ~90 days, leave briefly, then come back for another ~90 days, they'll be hugely suspicious; if you leave for not much more than 90 days and then try to come back for  about 90 days, they'll still be pretty suspicious.
Comment: thank you so much for sharing with us your experience, I very appreciate it.
Comment: @DavidRicherby that was the whole point I wanted to make with this answer, which got surprising attention.
Comment: @DavidRicherby but critically, if you have a good reason for two 90-day visits with fewer days between, the officer can let you in, because it is a ruleof thumb.  The Schengen area knows no such discretion.
Answer: All things being equal, no, it's not good idea: people entering to visit girlfriends/fiances/etc for long periods of time are at high risk of overstaying and/or working illegally, and you'll get additional scrutiny.
However, it's much worse to lie about why you're visiting, since immigration officers are very good at spotting any inconsistencies in your story and you're basically guaranteed to be denied entry if you're caught.  You also will be asked how long you're staying, and when you say "five months", they will ask a) why so long, b) how you're going to support yourself, and c) how do they know you will go back home.
So my advice would be to find another reason to go to the US and explain this when asked -- but don't lie, it has to be real.  For example, maybe you can enroll in some local training course that will assist you in your career when you get back, and if asked where you're staying, you can state that you're renting a cheap room from/sharing a flat with a "friend" you met in the Czech Republic.  (No need to mention that you're romantically involved, unless explicitly asked!)  Remember that they will likely know that you've already stayed for five months before, so be sure your explanation covers that and that your girlfriend knows what to say in case they call her.
Note: This all assumes you did not overstay during your previous visit.  If you entered the US using the Visa Waiver Program, you only get 90 days, so you may already be in hot water if you actually stayed five months.  (You're not stopped on the way out, because the US doesn't have exit immigration control, but this is recorded.)
Comment: I think 5 months/ 2months /5 months pattern more raises flags than merely visiting a gf/bf in this case mind.
Comment: Presumably, being able to point to something specific he's returning home to would also work (e.g. "and then I've got a course / job / major event in 5 months in the Czech Republic which I'll be returning home for)
Comment: @user568458 That would be helpful, but the immigration office will want to know what he's doing in the US for those five months.
Comment: @Superbest no, the immigration officer cannot extend the VWP 90-day window.  They have discretion on a normal B visa entry, but not for the VWP.
Answer: It is neither a good or bad idea, it's your only option because it is the truth.
Getting caught on a lie would surely make things worse, so unless you are a conman or a politician, I would not advise testing USCIS officers ability to catch liars -since that's what they do for a living-.
Personally, I spent many months (never more than 3 at a time, since that's the limit for the Visa Waiver program) in the US visiting my girlfriend, always said that was the reason for my trip, and never encountered any problem.
Comment: @MikeScott Then you get asked what are your friends names and what kind of great relationship you have with them that you're willing to spend so much money visiting them that often. You're probably nervous enough at this point to lie and make up names and stories, and even if you do the less stupid thing and admit that "your friends" is "your girlfriend", the officer may wonder why you didn't admit that at the beginning and if you have anything else to hide. In my experience, being 100% honest from the very beginning will help you avoid problems.
Comment: @MikeScott Calling your romantic interest a "friend" is most certainly considered deception by immigration officials.
Comment: Don't lie, but don't give details. "I'm visiting friends" is not a lie, but avoids unnecessary detail.
Comment: I have to agree, being vague is a rather obvious tactic that you might be trying to hide something - or even making the whole thing up, which results in further questioning. The plan you want to go with is to bore them with every tiny detail until they get tired of listening to you and wave you through.
Comment: @DoubleDouble Agreed with you and Mike.
Answer: I would say that it depends with a bias towards to the other answers saying "don't mention anything they don't specifically ask".
My wife is from Ireland and came back and forth to the US 3 months on, 3 months off (both the limits of each interval). She did this a few times (maybe 4 or 5) without any problems. However one of those last times, she was taken into a little room and basically harassed about it. They told her that she needed to get her act together, and "you know you can't just get married over there" kind of thing. They let her through, but were very suspect of it and knew that something might have been going on.
Long story short, we filed for K1 visa and 13 months later (with no trips by either of us) we got married. It was hard, and the phone bills were huge, but we're still together nearly 11 years later.
So, it can work out but you are raising their suspicions that you are trying to "sneak" your way to the US.
BTW, if you do decide to get married, DO NOT just get married. Do the visa thing. Do your paperwork, pay your fees and wait in "line". This will save you a lot of headache and a potential multi-DECADE ban from the US and crazy INS vists and just basically government shenanigans. When my wife was in the immigration office in Dublin, she met a couple that just got married willy-nilly thinking it would work. The woman was banned for 10 years. Another newspaper story of nearly the same situation reported a ban of 30 years. US gov't doesn't appreciate you doing things out of order.
Comment: @kiradotee: hard as it is to believe, there was a time long ago when those things did not exist.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/47396/discussion-on-answer-by-coblr-is-it-a-good-idea-to-mention-to-the-usa-immigratio).
Comment: The phone bills were huge? What about Skype, Facetime, etc?
Answer: The problem is your behaviour is going to look suspiscious. What are you going to do during the day? Tourist type activities and dossing around are going to wear thin after a while, and given it doesn't seem you are especially rich, you may get tempted to work illegally. Spending more time in than out without a very good reason looks like migration, not visits. Unlike some places, the USA doesn't have a hard and fast rule on time in versus time out but that doesn't mean you won't get denied if they think you are trying to immigrate.
You may very well intend to take a break from study/work for a while and move back to your home country with your girlfriend when she finishes her studies, your family may well be willing to pay for this, but the immigration officer has no way of confirming you or your families' real intentions.
So what are your options?

Try and keep doing what you are doing, it's not illegal per se (assuming you get the visa, 5 months is too long for a single trip under VWP) but the more times you do it (you don't say how long your girlfriend has left on her course or what her plans are after that) the more risk you run that you will be denied a visa or denied entry. Entering the US for you is a privilege, not a right, which means you have little recourse if they say no.
Make short visits making sure you spend more time at home (or at least outside the USA and its immediate neighbours) than in the USA. Maybe have your girlfriend come and visit you instead sometimes or meet up in some third country.
Get some other legitimate reason for long trips to the USA. The most obvious would be to start a course of study at a US college/university.

Marriage may also be a possibility, but in the short term is likely to make things worse, not better, and should of course only be done if you really believe you will stay with the person for the rest of your life. Using a sham marriage to immigrate is illegal and carries stiff penalties.
Answer: The ONLY important question here is not being asked yet: What does your visa say?
If you have a typical tourist visa, I think it should be 3 months in any 6 month period. If that's the case and you stayed 5 months, that's a problem and it doesn't matter whether you say something about your gf or not. If your visa allows you to spend 5 months, 3 months out and 5 months in the US, then it's not relevant what you say (although I agree it's not a good idea to offer up more information than asked).
Comment: " If your visa allows you to spend 5 months, 3 months out and 5 months in the US, then it's not relevant what you say." I disagree.  A US visa doesn't guarantee you the right to enter the country.  It gives you the right to come to the border and ask to be let in.  No matter what the visa says, if the immigration officer believes that you are planning to work, immigrate, etc, you can be refused entry.
Comment: The VWP allows 90 days per visit.  A B-2 visa allows up to six months per visit, which can be extended by application up to one year.  In both cases, there is no strict rule about how many days must be spent outside the US between visits.  General statements about a "typical tourist visa" are not particularly helpful in a conversion about a specific country's visa policy.
Comment: The OP is likely a Czech citizen, in which case they can use the Visa Waiver Program to travel to the USA without a visa for up to 90 days.  Agreed though that, if they did indeed exceed 5 months continuously, they'll be in trouble.
Comment: @jakub-kohout Read the comment above. If you exceeded 3 months the first time, you might be in trouble.
Comment: @NateEldredge a valuable distinction. Thanks for clarifying
Answer: I came to USA on holiday for 3 months on a visa waiver to visit a friend and  do a few road trips but while here her uncle took sick so we did a road trip to see him. On our return to my friends house she received a phone call that her uncle passed away. We drove 13 hours back to attend the funeral. Needless to say I did not get to do my road trips. I returned home to the UK and stayed home a little over 3 months during which time I applied for a 10 year B1/B2 visa.I returned to USA in December last year with the intention of staying six months. I was stopped at the airport by immigration control and accused of living in USA. I was taken into a room and questioned about my visit my ties to the UK and my relationship to the person I was staying with. I answered each question open and honestly and to the best of my ability and was allowed to enter. Since then due to my friends illness and operations and also severe weather during the spring I was still unable to do my road trips so applied for an extension of stay. I asked a law firm to complete my application and stated the above as my reason to request an extension. It was granted. All I can say is if you are honest forthright and do not try to play the system then immigration will treat you fairly
I love USA I have many friends here and get invitations regularly but unfortunately I will not return here for at least a year after I land back in the UK.
Comment: One needs to read quite far in this post before one can see that it is intended to actually answer the question. It would decrease your risk of having the answer deleted as "not an answer" if you (a) use some paragraph breaks, and (b) summarize your answer _to the question_ up front instead of jumping directly into a long explanation of _your_ situation.
Answer: Yes you should say it. I went through this a number of times. Just make sure you say exactly how long you are visiting and bring some evidence (copy of a lease, college id, work contract) that you have a reason to return after your stay.
5 months is longer than the Visa Waiver Program allows (90 days). If you already overstayed this once, then you won't be allowed to enter on the Visa Waiver Program again for a certain period of time. You need to get a visa.
Comment: I believe that "a certain period of time" is, in this case, forever. "Previous Compliance and No Prior Visa Ineligibilities.

If you have had a U.S. visa before or previously traveled to the United States under the VWP or another status, you must have complied with the conditions of previous admissions to the United States, and you must not have previously been found ineligible for a U.S. visa." (https://travel.state.gov/content/visas/en/visit/visa-waiver-program.html)
Comment: I traveled on tourist B-1 visa which allows to stay 180 days and I stayed something around 150 days.


Optimal RPM when bicycling?

Question: Regarding the RPM (revolutions per minute) while bicycling: I have heard that a too low RPM is bad for your knees. Both too low and too high is a waste of energy. What is the optimal RPM when cycling?
Comment: This is highly individualized even among trained cyclists. There is always a "recommended" that people cling to, but you have to find out for yourself what works best for you. There is also a large difference between road, track, mountain, etc.
Answer: Short answer, it depends on what you're optimizing for and what you've trained for.
The general wisdom is that 80-90 rpm is ideal for reduction of muscular fatigue and 80-100 rpm (possibly as low as 60 rpm) is best for ideal oxygen usage. But those are values for trained cyclists. More recreational cyclists have been found to have the longest cycling time around 50 rpm. Basically, the faster your cadence, the better the blood flow, but the more that you have to actively "push" to keep pedaling at that speed, creating a tradeoff.

Optimal RPM when bicycling?


Is there a system of logic which denies DNI?

Question: From what I know, the law of double negation is often simplified as p <=> ~~p. Intuitionist logic splits the biconditional into DNI and DNE.
DNI: p -> ~~p
DNE: ~~p -> p
and denies DNE while affirming DNI. My question is whether there is a similar system which does the opposite, i.e., denies DNI while affirming DNE?
Answer: Yes there is. As you say, intuitionistic logic has DNI but not DNE. There are also dual-intuitionistic logics whose connectives operate in a fashion that is dual to those of intuitionistic logic. Dual-intuionistic logic has DNE but not DNI. Intuitionistic logic includes the law of non-contradiction (LNC) but not the law of exlcuded middle (LEM) so it is paracomplete. Dual-intuitionistic logic includes LEM but not LNC, so it is paraconsistent.
Here are a couple of references on dual-intuitionistic logic.
Yaroslav Shramko, "Dual Intuitionistic Logic and a Variety of Negations: The Logic of Scientific Research". Studia Logica 80, pp. 347-367, (2005)
Igor Urbas "Dual-Intuitionistic Logic". Notre Dame Journal of Formal Logic 37(3), pp. 440-451, (1996).
There is also another question on the Philosophy Stack Exchange about dual-intutionistic logic and some of the answers there contain references.
Answer: Just as Intuitionism can be translated to classical S4 modal logic, there is a logic based off of classical GL modal logic developed by Albert Visser called Formal Propositional Logic (FPL) which does not validate DNI. In general, if you take the Gödel-Tarski-McKinsey translation, but remove that the relation between states is reflexive, then the resulting propositional logic won't validate DNI. This is the result of that (P&~P)⊭⊥ without reflexivity.
Answer: My answer is just a remark to prove that what you call DNI follows from very basic logical assumptions.
Let us write

A1,...,An |- B

to say that B is provable from the assumptions A1,...,An.
A theorem is a statement A that is provable from no assumptions; to say that A is a theorem, we write

nothing |- A.

Consider a proof system where the following rules hold:

Modus ponens

For all statements A, B,

A, A -> B |- B.

??? (I don't know the name of this rule)

For all statements A, B, C,
if

A,B |- C

then

nothing |- A -> (B -> C)

Then, in this proof system, we have

|- A -> ((A -> B) -> B).

Moreover, the usual definition of ~A is just A -> FALSE.
Therefore, DNI is a theorem in such a proof system.
Comment: Your rule 2 follows from two right implication introduction steps! It's more commonly phrased as "given An U {B} |- C, then An |- B-> C". This works because -> is the material implication, but fails in some logics with a stronger conditional.


Confirmation of Direction of Electric Field

Question: After having just learned about electric fields I am trying to write down an equation for the net electric field at a point. Though aware of Gauss's law, I want to try to solve this problem with what I already know.
Say I have a function $Q : \mathbb{R}^3 \to \mathbb{R}$ giving me the charge at any given point in $2D$ space. I want to write down an equation $\vec{E} : \mathbb{R}^3 \to \mathbb{R}^3$ describing the net electric field induced by a point charge on any given point in $\mathbb{R}^3$.
But I'll start with a simpler idea. Let $q_1$ and $q_2$ be two point charges at $\vec{r_1}$ and $\vec{r_2}$ respectively. I want to find an equation for the components of the force of $q_1$ on $q_2$. Here's my problem. Coloumb's law $$\vec{F} = k\frac{q_1q_2}{r^2}\hat{r}$$ only gives the radial force. I need general equation to describe the components of $\vec{F}$ along $\hat{i}$ and $\hat{j}$, and $\hat{k}$. So I must somehow get the radial force components along the regular $\hat{i}$ and $\hat{j}$ axes.
My first intuition was to use the equation of projection (which, incidentally, I just learned in Calc III yesterday). Then, I would write down the new force vector $\vec{F_t}$ as projected onto the unit vector for the x axis.
$$\vec{F_t} = \frac{\vec{F} \cdot \hat{i} }{ \vert \hat{i}\vert^2}\hat{i} = \vec{F} \cdot \hat{i} $$
Substituting in $\vec{F}$ from Coloumb's law:
$$\vec{F}_t = \left(k\frac{q_1q_2}{r^2} \hat{r}\right) \cdot \hat{i}$$
With the field coming from $q_1$, the radial vector $\hat{r}$ from $\vec{r}_2$ to $\vec{r}_2$ can be expressed as
$$\hat{r} = \vec{r}_2 - \vec{r}_1$$
And then finally:
$$\vec{F}_t = k\frac{q_1q_2}{r^2} (\vec{r}_2 - \vec{r}_1) \cdot \hat{i}$$
Then, dividing by $q_2$, we can obtain the general electric field equation between two points $\vec{r}_1$ and $\vec{r}_2$:
$$\vec{E}(r) = k\frac{q_1}{r^2} (\vec{r} - \vec{r}_\text{ref}) \cdot \hat{i}$$
This equation for field relative to a point charge is really powerful. Choosing a point $r_2$, I can integrate $\vec{E}$ over a bounded region of $Q$ to find the net field at $r_2$.
What I am looking for
Very simple. I'm hoping someone can verify my derivation for the field equation ($\vec{E}$) is correct. We didn't discuss this is in class. Purely for my own enjoyment.
Answer: After thinking about it a bit I realized what I had been doing was wrong. The solution is a great triviality.
First, the electric field equation is along $\hat{r}$ which is a radial vector to any other point $\vec{r}^\prime$
$$ \vec{E} = k\frac{q}{r^2}\hat{r}$$
If the point particle is located at $\vec{r}_p$, the radial vector from $\vec{r}_p$ to some $\vec{r}$ is given by:
$$\hat{r} = \vec{r} - \vec{r}_p$$
Substituting this into the equation for $\vec{E}$:
$$ \vec{E} = k\frac{q}{r^2}\hat{r} = k\frac{q}{\left|\vec{r} - \vec{r}_p\right|^2}(\vec{r} - \vec{r}_p)$$
Now, given an arbitrary function for charge density $\lambda(\vec{x})$ we can define the differential field at a point as $d\vec{E} = k\frac{\lambda (x)}{r^2}\hat{r} d\vec{x}$.
Then, integrating over the surface on which $\lambda (\vec{x})$ is defined:
$$\vec{E}(r_p) = \oint d \vec{E} = \oint k\frac{\lambda (\vec{x})}{r^2}\hat{r}(\vec{r_p}) d\vec{x}$$
where $\hat{r}(\vec{r_p})$ is a radial vector to an arbitrary point $r_p$
For example, this image shows the electric field induced on a point $\vec{r_p} = 4\hat{i} + 2\hat{j}$. Summing these vectors for some infinite or finite region yields the net field at $\vec{r_p}$. If the integral doesn't converge...then I don't know what that would mean physically.


Do green lantern constructs need to remain tethered to the ring?

Question: Do a Green Lantern's energy constructs need to remain connected to the ring via a tether of green energy, or can they exist without being directly connected in such a way?
Answer: In theory, no, they do not need to be visibly connected to the ring.
Funnily enough, there are several such constructs listed on Top 10 Dumbest Things Green Lantern Has Ever Constructed.
Notably are the Green Lantern restaurant and waitress, space pirate ship, and glowing words "Bye Bye Bats", all of which are clearly do not have energy going from the ring to the constructs. I'm sure many other objects, especially vehicles the Lantern rides on/in and sitting places, do not have that tether.

Notice the waitress is untethered.

The words are not touching the Lantern here, nor connected by a tether.

This one is a little harder to tell, but there is no tether from the ring to any of the other objects, but mostly it's 3 spherical shields that I would point out.

I can't tell you why some constructs have that tether, and some don't. It could be that all of them are originally constructed by coming directly from the ring, but after all of their requisite energy has been pushed from the ring they don't need the tether to be sustained by the Green Lantern's willpower.
As soon as I read the question, this example came to mind:

This is a page from the graphic novel Kingdom Come. Alan Scott has constructed an entire space city from his ring, and as he sits in his throne you can see that there's no visible energy cord or tether connecting him to any part of the construct.
However, these scene is from an alternate future, and was never part of a canon timeline. Alan Scott is also not one of the Green Lantern Corps, and in this future he no longer even uses a ring. So it's not a good example at all, but the imagery is beautiful.
And that may be the key to the question: imagery. There's a good chance that tethers are only present or absent as the artist decides is necessary for the appearance of the scene. The absence of the tether in canon may have been established merely for its visual appeal, rather than mechanics.
Comment: But that's actually Alan Scott, and his ring works very differently.
Comment: @WinterKnight Fixed, now. I misremembered. I really need to get my copy of that out and read it again! Thanks.
Answer: I do not know of any cases where a Lantern (of any color) has sustained a construct without some form of tether.  When the tether is disrupted, the construct fades.
The most commonly seen Green Lanterns (Hal Jordan, Guy Gardner, Kyle Rayner, and John Stewart) typically project these tethers directly from their rings, but this is not strictly required.  With focus, tethers can be extended from the standard environmental shield that surrounds any active Lantern.
If a Lantern uses their ring to create something (such as using a construct welding torch to fix a steel support beam) the thing they have created remains even after the construct is dismissed.
There may be edge cases where a construct has remained for a short time without being sustained - if a Green Lantern willed the construct to remain before disconnecting, it might have enough residual power to stay coherent for a brief time - but I expect these would be few and far between.


Is $\int_0^{\infty} \frac{1}{e^{x^2}|\sin{x}|} dx $ convergent?

Question: I uaed comparison test $$\frac{1}{e^{x^2}|\sin{x}|} < \frac{1}{|\sin{x}|}$$
But $\int\frac{1}{|\sin{x}|} dx$ is divergent.
I don't know how to show whether the integral is convergent or not.
Comment: There is an interval around zero where $\sin(x)\le x $.
Comment: How do you integrate through the poles at $\pi,2\pi,3\pi,\ldots$?
Answer: $e^{x^{2}} \sin x  \geq x/2$ for $x$ near $0$, say $0< x <t$,  and $\int_0^{t} \frac  2 { x}dx =\infty$ so the integral is divergent.
I have used the facts that $e^{x^{2}} \to 1$ and $\frac  {\sin x } x \to 1$ as $x \to 0$.
Comment: Let $f(x)=\frac {e^{x^{2}} \sin x } x$. Then $f(x) \to 1$ as $x \to 0$. This implies that $f(x) >\frac  1 2 $ if $x$ is some interval of the type $(0,t)$. @Mina
Comment: Why $e^{x^2}sinx \geq \frac{x}{2}$?
Answer: Since $\lim_{x \rightarrow 0} \frac{e^{x^2} |\sin x|}{2x} = \frac{1}{2}$,
so there exists an interval $(0,~t)$, $\frac{e^{x^2} |\sin x|}{2x} < 1$,
which means $\frac{1}{e^{x^2} |\sin x|} > \frac{1}{2x}$.
Hence,
$\int_0^\infty \frac{1}{e^{x^2} |\sin x|} >
\int_0^t \frac{1}{e^{x^2} |\sin x|} > \int_0^t \frac{1}{2x} = + \infty$
Answer: I'd like to add to the other answers that concentrating on what happens near $x=0$ may give the incorect impression that only $x=0$ is a problem point of the integral. The denominator has a singularity at every point that $\sin(x)=0$, that means $x=k\pi, k \in \mathbb Z$.
Because $|\sin(x)|$ is $\pi$-periodic, the behavior of $|\sin(x)| \sim |x|$ that holds near $x=0$ also holds near $x=k\pi, k \in \mathbb Z$ in the general form of $|\sin(x)| \sim |x-k\pi|$. So near enough those points, we have $|\sin(x)| \le 2|x-k\pi|$
Near each such points, $e^{x^2}$ is bounded above by say $e^{x^2} \le 2e^{(k\pi)^2}$ simply due to continuity of $e^{x^2}$.
That means that near enough $x=k\pi, k \in \mathbb Z$, then we have for the integrand
$$\frac1{e^{x^2}|\sin(x)|} \ge \frac1{2e^{(k\pi)^2}2|x-k\pi|} = \frac1{4e^{(k\pi)^2}}\frac1{|x-k\pi|}.$$
The first factor is a constant, the second factor is known to not be integrable near $x=k\pi$, as the antiderivative is $\ln|(x-k\pi)|$.
So not only is $\int_{0}^{\infty}\frac1{e^{x^2}|\sin(x)|}$ not convergent, any $\int_{a}^{b}\frac1{e^{x^2}|\sin(x)|}$ where there does not exist an integer $k$ with $k\pi < a,b < (k+1)\pi$ is divergent, while if such $k$ exists, the intgral exists.


iOS SDK: Setting a variable in a second view controller - pushViewController

Question: I have made a pageView and each of the pages has a button. When i am pushing to a new view controller how can a pass in a variable. I have done this with android using intent.putExtra().
Here is my code in ios:
<code>- (IBAction)openButton:(id)sender {
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle:nil];
UIViewController *vc = [storyboard instantiateViewControllerWithIdentifier:@"ViewController"];
// i have tried: vc.magazine = @"Lifestyle"; but is saying property not found in ViewController
[self.navigationController pushViewController:vc animated:NO];

}
</code>
Here is the variable in the second view controller header file:
<code>@interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate> {
NSString *magazine;

}

@property (nonatomic, copy) NSString *magazine;
@end
</code>
Thanks in advanced, if you have questions please ask.
Answer: Found the fix, i have changed 'UIViewController' to ViewController then i could do
<code>vc.magazine = @"Lifestyle";
</code>
Thanks anyways.


Reference request for exactly solved models in statistical mechanics

Question: Can someone recommend a textbook or review article that covers exactly solved models in statistical mechanics, such as the six- or eight-vertex models? If there is literature at the undergraduate level, that would be ideal. I'm only familiar with Baxter's classic text on the subject, but this is tough reading for an undergraduate student.
Comment: Related: http://physics.stackexchange.com/q/26912/2451
Comment: Just for reference: The book by Baxter is: R.J. Baxter,
Exactly solved models in statistical mechanics,
Acad. Press 1982.
Answer: How familiar are you with exact solutions to the 2D Ising model?  If you don't know that forwards and backwards, I would probably start with some textbooks that cover that material in depth.  This would teach you some of the basics of transfer-matrix techniques and some other tricks about estimating eigenvalues, the thermodynamic limit, and so on.  The book that I like is Plischke and Bergersen's Equilibrium Statistical Physics (3rd Edition).  Plischke and Bergersen devote a whole chapter to solving the 2D Ising model, and work through it in a lot of detail.  One prerequisite is some Quantum Mechanics - the solution that they present uses Pauli matrices and some creation and annihilation operators.  They also do an Ising model on a fractal lattice (and on a chain, of course), both examples that can be solved exactly.  This textbook won't teach you six- or eight-vector models directly, but if you work through it, Baxter will be a lot easier.
There are scanned copies floating around on the net - just google it if you want a preview.
Comment: I am familiar with the two-dimensional Ising model and agree that it is a good warm-up for the six- and eight-vertex models. I will take a look at Plischke and Bergensen's book. Many thanks for the reference.
Answer: I would like to add that it is very important to know what you can find out without knowing the exact solution. Kardar's book "Statistical physics of fields" teaches that in a very engaging way. To get quickly started, I suggest the topics of Scaling theory, and real space renormalization in 1-d ising model. Your motivation in keeping up with Baxter will grow due to this book.


Is where measurement is done the requirement for what gets to be called the computational basis?

Question: In Nielsen and Chuang, chapter 1.3.3 is named as "Measurements in bases other than the computational basis". This name confuses me - after the measurement is done on a new base, doesn't this new base become the computational basis?
Answer: The "computational basis" really doesn't refer to anything more than that basis you choose to label with the symbols 0 and 1. It is an arbitrary designation and independent of what operations (eg. measurement) you are actually doing on the qubits.
Comment: That is true _only_ if you perform the measurement in the computational basis! If you perform the measurement in a different basis, the result collapses to an eigenvalue of that different basis.
Comment: Thank you for the reply! However, doesn't the measurement give a result that collapses onto either one of the computational basis, and hence defines what's actually the computational basis?
Answer: The computational basis is just a convention for the $Z$ basis, as its orthogonal basis is $\{|0\rangle, |1\rangle\}$; which is  analog to the bit in classical computation, hence the name.
So in theory, yes, you can call computational basis any basis you want as long as you clarify what convention are  you following, but the most common convention (and, in reality, the only one I've seen) is to call the $Z$ basis this.
Answer: Each base you are working with is a "computational basis", hence as it was mentioned before the standard one, is a conventional one in reference to the classical. The result of your measurements will be expressed in different amplitudes by will express the same phenomenon.


How can I open Java's Control Panel?

Question: How can I open Java's Control Panel to change the security settings?
Comment: What Java Control Panel?
Comment: Dash -> search "java" -> open java control panel -> open tab "security". It's that easy.
Answer: If you've manually installed Oracle Java it doesn't show up in the Dash (as far as I know).

Open a terminal
Execute the following command:
/usr/bin/jdk1.8.0_05/bin/ControlPanel

Replace /usr/bin/jdk1.8.0_05 by the path of your Java installation.
Answer: Open a terminal (Ctrl-Alt-T) and start
ControlPanel

Just a few moments later the Java Control Panel appeared.  I haven't checked yet, but it may be necessary to
sudo ControlPanel

to save your changes.
Comment: Pity the other answer was already accepted as this one is much more clean and succinct.
Comment: Shouldn't `sudo -H` be used here? I've been told running a GUI application as root can cause trouble.
Answer:
Open a terminal
Execute the command: jcontrol
Answer: Hit the super key, search for "java" and it will show, amongst others, "java plugin control panel" if it is installed that is.
Comment: Medium level is now removed.
Answer: Go to the Path you saved Java.
Type
cd jre/bin/
sh ControlPanel

Answer: as of java9... (Oct 2017)
This assumes you have installed java9 yourself (since the webupd8 PPA method is currently broken).  After repeated purging of all things java-related (especially the default-installed java), I've not taken the time to fix the "update alternatives" infrastructure, so that particular link to jcontrol is borked (that is, the answer above -- "just type jcontrol in a terminal window" -- does not work).
This also assumes you have a working java installation (java -version returns something).
 # ls -al `which java`

You'll get something back like this:
  lrwxrwxrwx ... /usr/bin/java -> /usr/java/default/bin/java

So your command will be:
 # /usr/java/default/bin/jcontrol

Now, you can fix the alternatives link (the quick-and-dirty way), so you can just type jcontrol and have it work. I do recommend you use the update-alternatives structures (be sure you know what you are doing before taking these steps.  I suggest using ls -al to check the links).  This is done as root.  You can put sudo in front of the commands if you feel better about doing that.
# ln -s -f /usr/java/default/bin/jcontrol /etc/alternatives/jcontrol
# ln -s -f /etc/alternatives/jcontrol /usr/bin/jcontrol

How can I open Java's Control Panel?


Acronis + unixware backup and restore

Question: I want to use the Acronis in order to backup and restore UnixWare unix.
Please advice if Acronis can be used for UnixWare ?
I'm almost sure Acronis can backup/restore Linux but I am not sure about UnixWare.
Comment: In what capacity do you need it in?  Is it for workstations, servers, home?
Comment: I need to backup UnixWare machine , the disk is 36G , yes its server based on Pentium 3
Answer: Acronis is mostly platform independent, meaning that it will work with most mainstream OSs (Linux, Windows, Unixware, etc).
Personally, I have Backup & Recovery for my servers which should be what you are looking for.  Acronis is nice in that they will let you try the software before you shovel out the cash to purchase a full license so that you can see it is a good fit for you.
Should you go against getting Acronis, Symantec and EMC would be worth looking at for your situation.
Comment: please advice how Acronis shuld work , I have unixware machine connected to switch so acronis shuld work on other windows machine as client? or I need to download the acronis software in my PC card (PC card is like USB in my unixware machine ?)
Comment: Advice: Find someone who knows what they're doing to help you. My apologies for being blunt, but you quite obviously are below the threshold where we can help you via the Internet. It's time to hire a local consultant who knows how to get your network where it needs to be.
Answer: It appears as though it depends on what kernel your UnixWare machine is running. According to http://www.acronis.com/backup-recovery/server-linux/#requirements, the newest version works with Linux with kernel 2.4.20 or later and glibc 2.3.2 or later.
With Acronis Backup & Recovery you can install the software agent on the server and administer the software via the server (Manage this machine). Alternatively, you can connect to the machine via the Acronis Management console and set up your backups that way from a central location.
You can hook up a local drive / tape drive to the server being backed up, or you can backup to a network device as well.
Hope that helps.

Acronis + unixware backup and restore


Install Ubuntu to USB without cd

Question: I'm trying to install Ubuntu onto USB to create a portable OS, but i don't have a cd drive installed nor a second memory stick. Was wondering if there is any clean way of installing the Ubuntu onto the stick that will only require the memory stick?
Comment: Please tell us what you have: What computer - brand name and model? How much RAM?  What operating system are you running now? What memory stick is it - brand name and size? This information helps us give relevant advice.
Comment: Likely no. You'll need some way to start the installer, which is hardly possible without a working PC. Given there is one around with Ubuntu, you could boot from an Ubuntu ISO with GRUB.
Comment: i was thinking that maybe partitioning the hard drive could do the trick. worst case scenario i have couple of unused devices i could nuke to use for the installed.
Answer: These steps will create live+installer versions of Ubuntu, that can be booted on most Computers.
If you are using Windows:

Download the Ubuntu ISO file
Download Rufus USB Installer
Open Rufus, and click the CD-ROM icon (right hand side, about 2/3rds down) and choose your Ubuntu ISO file and click on the "Open" button
Click the "Start" button
When asked to download syslinux, click "Yes"
When asked about a "Hybrid Image", click "OK"
When you are warned that it will destroy all the data on your USB drive, make sure you've selected the correct USB drive, then click "OK"
Wait until it is complete.  This can take a fair few minutes depending on the speed of your USB drive, and the USB speed
Boot from the USB drive and proceed as normal

If you are using Ubuntu:

Download the Ubuntu ISO file
Open the dash and search for "Startup Disk Creator"
When found, click on it to launch
Once open, click on "Other" and browse to your ISO file.  Click "Open"
Choose your USB drive in the bottom box, then put a check in the box marked "Make Startup Disk" and click "Yes"
Boot from the USB drive and proceed as normal

If you are using another distro (generic instructions assuming your USB is /dev/sdb):

Download the Ubuntu ISO file
Open your terminal and cd to the folder that you downloaded the ISO too.
Type sudo umount /dev/sdb
Type `sudo dd if=.iso of=/dev/sdb bs=1M
Boot from the USB drive and proceed as normal
Answer: I am assuming that you want a Full install to USB.
Open VirtualBox.
Select "New" and make new Ubuntu machine.
Start Ubuntu machine and select Ubuntu iso.
Continue until you get to Try/Install window, select Try.
Plug in USB and activate.
Select install if you want a Full install to USB. Best to try this after unplugging internal HDD.
Select startup Disk Creator if you want a Live install.
Download and use mkusb if you want a Persistent install.
Allow the selected installer to do it's thing.
There are posts on Ask Ubuntu that detail the installation and use of VBox.

Install Ubuntu to USB without cd


How do I license a font I created to sell

Question: I just recently created a font using the Fontself plugin for Illustrator and I want to figure out how to protect my font with a license and distribute it.
The problem is that everything I've found online is for the user and how to purchase a font license, not license a font FOR purchase/distribution.
Answer:
Write a license agreement that satisfies your business objectives.  Or,
Find an open-source or other existing license that satisfies your objectives.  Or,
Pay a lawyer to write a license that satisfies your objectives.

Your objectives might include terms and conditions on when, where, or how your font can be used by a licensee.


Wake on LAN alternatives?

Question: I am attempting to set up my Pi-0-w to wake up a computer on a local network. However, Wake-on-LAN is not an option. Does anyone have ideas for an alternative? Perhaps a way to wake through a USB connection?
Comment: Is there a reason why WOL is not an option? Perhaps this is the problem you should be trying to solve. Otherwise you may want to look at [this](https://raspberrypi.stackexchange.com/questions/91920/how-to-wake-pc-from-suspend-via-usb-with-pi-0-in-gadget-mode) question and [this](http://www.isticktoit.net/?p=1383) related post on making the Pi-0 behave like a USB device such as a keyboard.
Comment: @RogerJones  Actually I asked that other question, however there were no answers of yet so I am trying a more general question.
Comment: @RogerJones, Yes, more than one.  The main computer I want to do this with does not support it, and also I would like for the solution to be "plug-and-play", without having to configure each PC.
Comment: Fair enough! My only suggestion is trying to get your Pi0 to act like a USB keyboard and send the appropriate key code to wake your PC as per the question I referred to. But, even that may need some configuring on the PC to allow USB devices to wake the PC up and also to prevent the USB bus from going into Suspend Mode. May not even work, hence why I'm not posting this as an answer. Good luck.
Comment: @RogerJones I have tried the idea of emulating a USB keyboard pretty extensively, and have not been able to get it to work. I am able to emulate the keyboard, but not enough to where I can signal a wake with it.   I am now attempting to emulate a bluetooth keyboard, to see if that will work any better.
Answer: I have used a crazy solution.
I've programmed a Particle Photon (but any wifi arduino will do) to "reset" the Raspberry Pi using the reset pin.
Expensive and crazy but works :)
Comment: OP wanted to turn on their PC, not reset their Pi.
Comment: It is true, I am looking to wake the PC, however this idea of interfacing with an Arduino might be the ticket.
Comment: @RogerJones You are indeed right but if you can reset a Pi with arduino it means that you can "push a physical button" with it. That button can be any button, including the on button on your pc :)
Answer: If you're okay with cracking open your computer case, you could use the Pi's GPIO through an optoisolator to trigger the PC's power button, like what is described in this tutorial. You would replace your PC's power button with the optoisolator (or wire the two in parallel), then use the Raspberry Pi's GPIO to control the optoisolator.
You could also use a relay board like the PowerSwitch Tail or a similar product controlled by your Pi Zero to remotely turn on and off power to the PC, then set the PC's BIOS to "restore from AC power loss" (this will make the computer turn on whenever power is restored). This would also use the GPIO pins.

Wake on LAN alternatives?