Is "SELECT COUNT(column)" faster/slower than "SELECT COUNT(*)"?
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better?
How to install Broadcom wireless drivers offline? I have installed Ubuntu alongside Windows 8.1. But the wifi is not working in Ubuntu (perhaps the drivers are not present), which worked fine in windows. Also I cant connect with Ethernet since my laptop does not have an Ethernet port. So is there any way for me to connect to the internet in ubuntu? Edit: Output of the terminal command  lspci -knn | grep Net -A2:  vikram@vikram-Inspiron-11-3148:~$ lspci -knn | grep Net -A2 01:00.0 Network controller [0280]: Broadcom Corporation BCM43142 802.11b/g/n [14e4:4365] (rev 01)     Subsystem: Dell Device [1028:0018]     Kernel driver in use: bcma-pci-bridge vikram@vikram-Inspiron-11-3148:~$    I did what Pilot6 suggested. Here is the output:    vikram@vikram-Inspiron-11-3148:~$ sudo dpkg -i *.deb [sudo] password for vikram:  Selecting previously unselected package bcmwl-kernel-source. (Reading database ... 163804 files and directories currently installed.) Preparing to unpack bcmwl-kernel-source_6.30.223.141+bdcom-0ubuntu2_amd64.deb ... Unpacking bcmwl-kernel-source (6.30.223.141+bdcom-0ubuntu2) ... Selecting previously unselected package dkms. Preparing to unpack dkms_2.2.0.3-1.1ubuntu5.14.04_all.deb ... Unpacking dkms (2.2.0.3-1.1ubuntu5.14.04) ... Setting up dkms (2.2.0.3-1.1ubuntu5.14.04) ... Setting up bcmwl-kernel-source (6.30.223.141+bdcom-0ubuntu2) ... Loading new bcmwl-6.30.223.141+bdcom DKMS files... First Installation: checking all kernels... Building only for 3.16.0-30-generic Building for architecture x86_64 Building initial module for 3.16.0-30-generic ERROR (dkms apport): kernel package linux-headers-3.16.0-30-generic is not supported Error! Bad return status for module build on kernel: 3.16.0-30-generic (x86_64) Consult /var/lib/dkms/bcmwl/6.30.223.141+bdcom/build/make.log for more information. modprobe: FATAL: Module wl not found. update-initramfs: deferring update (trigger activated) Processing triggers for man-db (2.6.7.1-1ubuntu1) ... Processing triggers for initramfs-tools (0.103ubuntu4.2) ... update-initramfs: Generating /boot/initrd.img-3.16.0-30-generic vikram@vikram-Inspiron-11-3148:~$ I'm confused. Running Fedora Linux, lscpu yields:  Architecture:            i686 CPU op-mode(s):          32-bit, 64-bit ...   But when I try to install a 64-bit program (Chrome) I get error like:     Package /....x86_64.rpm has incompatible architecture x86_64. Valid architectures are ['i686', 'i586', 'i486', i386']   I'm less interested in being able to install Chrome and more interested in why lscpu says that my CPU can run in 64-bit mode; clearly this can't mean I can run 64-bit programs. Can anyone clarify? Changing URLs in Google's Index I recently submitted a sitemap.xml in Google's Webmaster Tools and some of the pages already got indexed. The problem now is, that I cleaned my URLs with MOD_REWRITE in the .htaccess file afterwards and I would like the new ones to be indexed. The old ones should be removed from the Google Index.  Indexed Page:  www.example.com/article.php?=article=this%is%an%example   New URL:  www.example.com/article-this-is-an-example   Do I even have to remove them manually from the index in any way or do they refresh if Google crawls my new sitemap? I really wan't to prevent duplicate content.  Thanks in advance. Niven’s theorem proof. I couldn’t find any proof on the internet. I would appreciate an elementary proof , but any help would be appreciated!  Thank you. This question is from a set of optional, much harder problems from my first year analysis course, but the subject material is norms on $\mathbb R^K$.  (c) Show that there exists a constant $C &gt; 0$ such that for all $\mathbf x ∈ \mathbb R^k$, $||\mathbf x||\le C||\mathbf x||_\infty$  Hint: Use the standard unit vectors to write $\mathbf x = x_1\mathbf e_1 +. . .+x_n \mathbf e_n$, and use the triangle inequality.  (d) Show that there also exists a constant $c &gt; 0$ such that for all $x ∈ \mathbb R^k$, $||\mathbf x||_\infty \le c||\mathbf x||$  Hint: If it isn’t true, then you can find a sequence $⟨\mathbf x_n⟩$ such that $||\mathbf x_n||$ is bounded but $c_n := ||x_n||_∞ → ∞$. (Why?) Think about the sequence $⟨\mathbf x_n/c_n⟩$. The Bolzano-Weierstrass theorem may be of assistance.  Note that the unspecified norm represents any norm for $\mathbb R^k$. I've done part c), but am stuck on part d). I've had a look for proofs on other questions on MSE, but none of them seem relevant to the hint given, and frequently the terminology is too advanced for me.  I tried considering the case if it isn't true, as suggested, but I can't see how to bound any sequence using that. Any help would be much appreciated. When upgrading to Ubuntu 14.04 from Ubuntu 12.04 I am getting the following error:     W:Failed to fetch    Unable to find expected entry 'non-free/source/Sources' in Release   file (Wrong sources.list entry or malformed file) , E:Some index files   failed to download. They have been ignored, or old ones used instead. Accused of cheating on online exams Why or how did Agen Kolar and Saesee Tiin seem to die so easily without any resistance? The pronunciation of the word "a" Most times we hear that the letter A is pronounced as [ə], but sometimes I hear that it is pronounced as [eɪ] in American English. Such as the following sentence: From VOA Special English:  She says governments must make that goal of a continental free trade area a reality.  The first A is pronounced as [eɪ], the second A  is pronounced as [ə]. Why? Does it have some regularity in it? How do I save a file with managed_file in a theme? I'm developing a theme that it requires to have a header image on the front page, so I have this.  casper.theme  function casper_form_system_theme_settings_alter(&amp;$form, &amp;$form_state) {  $form['theme_extra']['front_page_background_image'] = array(     '#type' =&gt; 'managed_file',     '#title' =&gt; 'Front Page Background Image',     '#description' =&gt; 'Add background image for the front page',     '#required' =&gt; FALSE,     '#weight' =&gt; -4,     '#upload_location' =&gt; file_default_scheme() . '://theme/backgrounds/',     '#default_value' =&gt; theme_get_setting('front_page_background_image' , 'casper'),     '#upload_validators' =&gt; array(         'file_validate_extensions' =&gt; array('gif png jpg jpeg'),     ),  ); }   However, after it, while the file been missing and after some reading, I find out that is because managed_file does not save your image permanent.   There are similar questions:    is specified to Drupal 7.  is using "file" type instead of managed_file. I already tried something similar to what the Mayo theme is doing, but I was not able to successfully figure it out.   How can I save my image permanently? How Deep Are Bender's Insides? Bender often pulls large objects from his torso cupboard, but how deep or how much empty space is he capable of storing? Can he bend space around the perimeters of the frame of his torso's door? If that is the case, does it also bend time? I suppose he might bend in more ways than one... I am aware it is common practice to standardize the features for ridge and lasso regression, however, would it ever be more practical to normalize the features on a (0,1) scale as an alternative to z-score standardization for these regression methods? Prove $\forall n\geq 2,n\in\mathbb{Z}$, $(n+1)\mid(n^3+1)$ Question: Prove $\forall n\geq 2,n\in\mathbb{Z}$, $(n+1)\mid(n^3+1)$    I know that it is possible to solve by factoring $n^3+1$ and showing that $n+1$ is a multiple, but I would like to show this via induction.  Attempt: Using induction:  Let $n=2:3\mid 9$, so true for $n=2$  (1) Assume true for $n=k:(k+1)\mid(k^3+1)$, so $(k+1)r=k^3+1$ for some $r\in\mathbb{Z}$  (2) Let $n=k+1:(k+2)\mid(k+1)^3+1$, so $(k+2)s=(k+1)^3+1$ for some $s\in\mathbb{Z}$  From (2) we have $(k+1)s+s=(k+1)^3+1$, subbing (1) into (2), I get $k^3+1+s=(k+1)^3+1$  Therefore $k^3+s=(k+1)^3$.  Setting $s=3k^2+3k+1$, this holds.  Where am I going wrong, is the proof valid, any help would be greatly appreciated. Story about a future with races Safari Extension to Manage Tabs? I'm looking for a more efficient way to manage my tabs in Safari. Specifically something that allows me to move multiple tabs at once to a new window.  I often find myself following a link for a new subject/idea, then another, and so on and so on, until I find myself with a dozen tabs that should really be in their own window, but it's a pain to manually find and drag each one. I'd love to be able to do it in one fell swoop. Any suggestions? Why does an unhinged body rotate about its centre of mass? If a force is applied to a body which does not act through its centre of mass, it rotates about its centre of mass and not any other point. Why? Auto confirm when running bash scripts? I just updated my iPhone 7 Plus to iOS 13 tonight and noticed that the post menu in the Stack Exchange app became close to unreadable, because the font/text is too large to be properly displayed. Luckily we can still recognize the icons...    (Yes, app development has been frozen for quite a while but the app continues to serve me well.) I read about Drupal behaviors today, and I tried writing the following code.  (function ($) {    Drupal.behaviors.mymodule = {     attach: function (context, settings) {       $('#mymodule_id', context).change(function () {         alert('Handler for .change() called.');       });     }   };  }(jQuery));    Is Drupal.behaviors.mymodule the namespace? What are the context and settings parameters passed to the Drupal behavior? Is this the equivalent of document.ready()?   Can I attach any number of functions?  Can I define JavaScript functions which will be called somewhere? Formation of ammonia from air and moisture On extended bicycle trips I sometimes slept under a plastic sheet, which helped with mosquitoes on hot nights. But there was a noticeable build-up of ammonia which made this almost impossible for more than an hour or so at a time.   Air is mostly nitrogen $(N_2)$ and there is always water (containing hydrogen) on a humid day. But I wonder about the mechanism for the formation of ammonia under these circumstances? There are (according to Wiki) trace amounts of methane and $H_2$ in the air. But methane and hydrogen (g) are I think pretty stable.   I wonder if the presence of exhaled air (containing $CO_2)$ could be a factor?  Thanks for any ideas.