How to best respond to a request to send a passport scan by unsecured email?
What harm can be done with a copy of one's passport?
Can I travel in UK before switching to a study visa? As I read in general visitor visa Terms &amp; Condition, I would only be granted to stay up to 6 months in UK. However I am planning to apply for General Student Visa to further my studies. Would it be possible for me to enter UK as visitor for first 6 months/less before I apply for student visa in the same year if I want to travel and study on the same year? Difference between "I'm home" vs "I'm at home" I've seen in every introductory material on LaTeX and in a lot of code of other people (event experts) that the \newcommand command is used by wrapping the first argument in braces, even if it seems unnecessary to me.   The braces are consistent with the usual way arguments are passed to LaTeX commands (since usually the braces are used even if the argument is made of a single token, for consistency and clarity), but in this single case they appear very ugly to me and in my opinion they lower readability.  But these are opinions, while the question is technical: is there any technical reason why one should write this:  \newcommand{\mycmd}[1]{Hello #1}   instead of this:  \newcommand\mycmd[1]{Hello #1} Configure Postfix to use external MX servers for delivery of local mail if user is unknown I have a following setup:   linux box with postfix configured to be responsible for example.com domain domain's MX servers are configured so that mail sent to example.com is sent to google mail servers several user accounts on linux machine exist (same machine also hosts example.com site)   When someone from the outside attempts to send mail to address ending with @example.com, it gets routed to google mail (and there handled appropriately).  When linux machine tries to send mail to outside world, mail is delivered correctly, as reverse dns and spf records are configured correctly, so linux machine is valid mail sender for example.com domain (along with google mail servers).  However, here's the problem. When php application (hosted at linux box) tries to send mail to someuser@example.com (and someuser doesn't exist on linux box), it fails, since it doesn't even consult google mail servers, but postfix smtp locally concludes that "someuser" is unknown.  So, the question is: how do I tell postfix to relay mails sent to @example.com domain to google mail servers (so, to servers specified in MX records), IF and only if a mailbox is not found locally. Continuing example in Beamer What's the difference between stochastic and random? When are infinities okay? I'm a little confused about how to handle infinities in physics. On the one hand, I always here things like infinities are not physically tenable answers. GR can't answer anything about the origin of the universe because of singularities. Throw away the radial solution that gives an infinite potential when solving the Laplace equation in spherical coordinates. But then there are other times that the infinities are okay. For instance, it is usually okay to set the reference point for your potential at infinity. There are certain times in David Tong's quantum field theory lecture notes where he seems to almost to hand wave away infinities. So, philosophically, physically, and mathematically when are infinities okay, and when are they not okay? Can I travel domestically within the United States with my USA expired passport? I need to fly domestically within the United States. The only ID I have is an expired USA passport.  Can I use that to pass T.S.A.?  Can I use it as ID? Printer not recognized on Ubuntu Libre Office I am running 14.04 and have a HP Deskjet 2545 wireless printer which is supported by Ubuntu. I have run HpLIP, the latest version and installed the printer.  The printer is recognised by Ubuntu, printer and network, but LibreOffice do not see the printer. Only a Generic printer.  I don't know what to do anymore and would like to get some good advice What should be in the sources.list for Kali Rolling Linux? This is exact content from my sources.list:  #  # deb cdrom:[Debian GNU/Linux 2016.1 _Kali-rolling_ - Official Snapshot amd64 LIVE/INSTALL Binary 20160830-11:29]/ kali-rolling contrib main non-free #deb cdrom:[Debian GNU/Linux 2016.1 _Kali-rolling_ - Official Snapshot amd64 LIVE/INSTALL Binary 20160830-11:29]/ kali-rolling contrib main non-free   I couldn't install the Synaptic package manager and was told to modify sources.list.  I googled a lot and added some repos into it and ran update and upgrade command only to see Kali crash... I had to recover it.  Please mention the exact content that should be there to ensure that Kali Linux works. Reoccurring Bent Axles, any reasons or upgrades? Earlier this month I had a issue with a broken axle.  It was the original that was sold with the bike and lasted around 5,000 miles.  I went to my LBS and bought a new axle (unbranded, labeled, etc, paid $13, came with cones, spacers, and hardware).  I did the install myself and had everything adjusted nicely.  The next time I rode it was on my commute to work, but I didn't get 4 miles into it when I found that I bent the axle.    I took the wheel to the shop but they wouldn't do anything about it since I didn't have them do the work.  However, I figured this was a fluke and asked them for a new axle and to true the wheel.  Once again I did the install of the axle and only got 15 miles out of it this time before bending it.  Before I got home I felt the wheel get stiff, but it stayed true.  The question is what will be a cause of bending 2 axles in 20 miles?    I think the guy at the shop said it was a cro-moly axle (while talking to another person today at the shop, these may not be), and he couldn't believe that I bent it.  If so, where would such an axle fall in the quality hierarchy?  Or is my hub toast?  While the wheel was being repaired, I swapped to a new original wheel for about 2 weeks.  I have not had any issues with it, but I wanted to keep it as new as possible.   Reading other questions I saw a comment that said not to use a hub where the bearing was catching.  I did have one in this wheel but I figured since it is a cheap wheel I would just burn it up and move on to a better one.  Besides, it has lasted 5k miles without issue to this point.  The bike in question is a 2008 Schwinn High Timber with Joytech freewheel hubs.  I do use a trailer with this bike using a Burley axle hitch.  While I had the hitch installed on both axles I bent, I did not have either trailer hooked up to them.  Something I would like to note is that when I removed the first bent axle (axle #2) that the cones on it had a wavy bearing track.  I didn't think too much of it, and I put them on axle #3.  Only having a few miles on them shouldn't have made a difference? What do \makeatletter and \makeatother do? Many LaTeX “hacks” begin with \makeatletter and end with \makeatother. What do these commands do? Diagonalizable matrix with parameters $$     \begin{bmatrix}     -2 &amp; -2 &amp; 0 &amp; 0 \\     -b &amp; -b &amp; 0 &amp; 0 \\      0 &amp; 0 &amp; -4 &amp; 4 \\      0 &amp; 0 &amp; b &amp; -b \\     \end{bmatrix} $$  I have this matrix and I need to find the values for $b$ that this matrix won't  be diagonalizable.  For what I got this matrix is diagonalizable for every $b$ value.  Please write me also the final answer, thank you very much. I need to take a screenshot that records my Eclipse IDE menu item status. For example, if I clicked the "Project" menu and there comes a list of menu items. I need to record those menu items.  The problem is when the menu item list window (which works like a context menu window) has the focus, the screenshot function is not working. I tried everything on this  and nothing works as long as the menu items window is opened. Any mouse click will close the context menu window, so I cannot use mouse either. However if there is no context menu window opened then screenshots works fine.  How can I record the screen with context menu window displayed? How do you remove Nvidia's proprietary drivers? I always seem to have grief with Nvidia drivers and have often had to re-install Ubuntu: is there a better way to remove them? When I first installed the drivers, the display came up on 640 by 480.  I managed to set 2 screens to 1024 by 780 which was usable, but then Ubuntu recommended installing proprietary drivers (nvidia-current-updates 295.40-ubuntu1). After doing this and re-booting it shows LAPTOP and offers only 640 by 480 on a single screen.   Is there any way to revert to the original driver? Is there any way to find out if the new drivers work before installing them? - For years I have been hoping that it would be all fixed in the latest release… I always seem to fall for this! How does this JavaScript/jQuery syntax work: (function( window, undefined ) { })(window)? Find My iPhone Email Notification Is the email notification from Apple that your device has been tracked using Find My iPhone a new feature? Ephemeral error message: "cryptsetup: unknown fstype, bad password or options?" I activated disk encryption for my Ubuntu 15.10 64bit installation and get every time after entering the (correct) password the error message:  cryptsetup: unknown fstype, bad password or options?  But after few seconds (without any further interaction) this error message is replaced by the expected message:  cryptsetup: sda5_crypt set up successfully  That's it and the system is started.  Any suggestions what could be the problem? Is it merely cosmetic or serious? Dropdownlist control with s for asp.net (webforms)? Can anyone recommend a dropdownlist control for asp.net (3.5) that can render option groups? Thanks Suppose there is a message that is encrypted with AES-128-CBC.  The message is as follows, new lines are used to delimit the 16 byte boundary for each block:  Wire funds from: Alice to Bob in   the amount of $ 1   Because this message is encrypted using CBC mode,  any modification of the first block of cipher text would propagate throughout the message.   However, the amount of the fund transfer falls in the last block.  I am under the assumption that an attacker can use the property of  to alter the last block and produce a valid amount that is greater than \$1 in far fewer than $2^{128}$ operations.   Is this a correct assumption?  Is there a name for this attack or do you know of a real world example?    My instinct is that if you just need one byte of the 16 byte block to be of a specific value then it would only require $2^8$ operations because the other 120 bits of the plain text could be any value. For example lets say we wanted the last block of cipher text to decrypt to 9\0 (where \0 denotes a single null byte, and the message would be interpreted as \$9), then it would take only $2^{16}$ operations to find this cipher text block.  Is there something I am missing?