Which one is correct and why?   Appropriate management and supervision of tourism centers is essential. Appropriate management and supervision of tourism centers are essential.
I was surfing the internet the other day when I found this phrase: Instead your precious time and attention is wasted. To my ears, it sounds wrong. But I'm not a native English speaker, so I consulted with a number of them, and some of them said that it was "is" because the adjective modifies only the noun "time" and not "attention". Others said it "is" because that's just how it is. But I still believe it should be "are". Any help is appreciated.
independent variables in Random forest model Struct padding in C++ Limit of $(\cos1/n)^{n^2}$ when $n\to\infty$ I've been trying to solve this limit: $$\lim_{n\to \infty} \left(\cos\left(\frac{1}{n}\right)\right)^{n^2}$$ I solved it using l'hopital but I have to try in another way. I tried to make the expression:  $$ \lim_{n \to \infty}\exp\left(n^2\ln\left(\cos\left(\frac{1}{n}\right)\right)\right)$$  but it didn't work out for me... Choosing variables to include in a multiple linear regression model If gravity isn't a force, then why do we learn in school that it is? Every partial order can be extended to a linear ordering How do I show that every partial order can be extended to a linear ordering?      I think that I manage to prove that claim for finite set, how can I prove it for infinite set?  Thank you. I'd like to be able to easily transfer large files wirelessly, fast, between Android devices - preferably without requiring root.  As a secondary objetive, it wouldn't hurt if the same solution could be used, to transfer files between the Android devices and a Windows PC.   Specifically, I'm trying to exchange files between my Nexus 7 (Android 4.2.2) and Samsung Galaxy S2 (Android 4.0.4).   Bluetooth is simply too slow, so that's out of the question Transfer via the Internet is also not an option, hence so is cloud-based solutions Only Nexus 7 supports NFC, so that's out too  looked promising and very simple, but does not work on "Devices that don't have WiFi Tethering setting, such as the Nexus 7"   Wi-Fi direct ( and up) seems to be a decent lowest common denominator between my two devices, however...  Galaxys S2's native Send via Wi-Fi Direct sees the Nexus, but seems to get stuck in the "Connecting..." most times. When there finally seems to be breakthrough, I get "Waiting..." and a spinning circle. Even if it worked, it would only allow me to send from the Galaxy S2 to the Nexus 7, as a similar option os not present on the Nexus 7.  J4velin's  is no longer available in the Play Store, with the following explanation:     WiFi Direct drivers are broken on many devices, which led to users leaving negative reviews for this app. As I don't see any sense in keeping a free app published when only getting 1-star-ratings (for an issue which only your device manufacturer can fix), the app is no longer available at the Play Store.   Nick Adams'  seems flaky at best. Invations from Nexus 7 to Galaxy S2 are never received. Invitations from Galaxy S2 are mostly received, but even when accepting promptly, the peers doesn't always show as connected. When they finally do, usually after quite a long wait, I can select a file to send but it's never transferred -  "Transfer failed" it says almost immediately in the notification bar.  budius inc's  is working slightly better, but still very unreliable. I actually managed to (occasionally) send files both ways, but never when attempting connection from the Nexus 7. To send from the Nexus 7 to the Galaxy S2, I had to go through this akward manoeuvre:   Share the file on the Nexus 7 via the WiFi Shoot intent Start the Receive WiFi Shoot app on the Galaxy S2 Invite the Nexus 7 from the Galaxy S2 (never the other way around!) Accept the invitation on the Nexus 7 Press the Shoot button on the Galaxy S2   Take the whole switching back and forth between devices, and garnish with random delays or failures in any step of the process...  Is there really no easy, reliable, fast way to transfer files directly between different Android devices?  Generally, my experience with Wi-Fi Direct is all but positive...   A device often won't even see a device lying next to it Sometimes, it will see the other device, only to have it disappear from the list, before I have the chance to connect When I do have a chance, invations are not realiably received (from Galaxy S2 to Nexus 7 mostly reliable, but never worked the other way around) When invitations are received (and accepted), a partnership rarely manages to be setup ("invited" or "connecting") And even when that happens, some apps can't seem to transfer files through it...   *Sigh*  Maybe J4velin's explanation pretty much sums up the sad state of Wi-Fi Direct on Android, which otherwise seemed as the best solution to my quest? in my earlier question you can find at:   i describe my error:     I'm using an Asus Zenbook UX562F with an integrated GTX 1050 Max-Q.   After the installation, I installed Nvidia-390 and updated the kernel   with ukuu to 4.20.17 to fix no sound issue.      After the reboot, everything went well and I did:      apt-get update apt-get upgrade + J      All was done well, so I restarted and on the next boot after selecting   Ubuntu in GRUB it gave me a long black screen (violet screen) where   nothing changes after so much time.      I tried to add nomodeset and noveau.modeset=0 single and together but   didn't help so I don't know what to do.   After investigating deeper by installing packages and try to boot i found out that the package which is causing the error is:  intel-microcode   when i purge and block this package with:  sudo apt-get purge intel-microcode sudo apt-mark hold intel-microcode   before upgrading wuth  sudo apt-get upgrade   my system is able to boot normal.  The problem i see is that as i understand it the package protects my intel cpu  Intel® Core™ i7 8565U 1.8 GHz   is vulnearable to meltdown attacks which get fixed by the package.  What can i do to fix the vulnearbility and also get my system to a bootable state?  Thanks for your help Vimu  Edit: I used the manual update technique mentioned at (in german):    and i used the files from the intel github repo:    with the following code mentioned in the tutorial to update the firmware microcode files  sudo cp intel-ucode/06-8e-09 /lib/firmware/intel-ucode/ echo 1 | sudo tee /sys/devices/system/cpu/microcode/reload   i overwrote the old microcode firmware with the newest available on the intel repo  it leada to a bootable system  will this be the best possible fix without upgrading the intel-microcode package provided by apt? ETS() function, how to avoid forecast not in line with historical data? How to solve "permission denied" when using sudo with redirection in Bash? What's the difference between package managers? What are the differences between apt-get, aptitude, and synaptic, and which one is the recommended choice for normal day-to-day package management?  This is a basic question, but I think it'd be good information to have on the site, and besides I am relatively new to Ubuntu so I could use an expert explanation. Why log-transforming the data before performing principal component analysis? Im following a tutorial here:  to gain a better understanding of PCA.  The tutorial uses the Iris dataset and applies a log transform prior to PCA:     Notice that in the following code we apply a log transformation to the continuous variables as suggested by [1] and set center and scale equal to TRUE in the call to prcomp to standardize the variables prior to the application of PCA.   Could somebody explain to me in plain English why you first use the log function on the the first four columns of the Iris dataset. I understand it has something to do with making data  relative but am confused what's exactly the function of log, center and scale.  The reference [1] above is to Venables and Ripley, Modern applied statistics with S-PLUS, Section 11.1 that briefly says:     The data are physical measurements, so a sound initial strategy is to work on log scale. This has been done throughout. Why non-measurable sets exist? What Is the reason behind the fact that $\Bbb R$ is not a complete measure space? Is it only due to the cardinality of  $\Bbb R$? Or other structures on  $\Bbb R$ also play a role? Can one make every subset of  $\Bbb R$ trivially measurable by assigning them to a number of a complete ordered field of the cardinality $\aleph_2$ ? Dropping articles in the title (of an article or a section) or in the caption (of a figure or a table)? What's the general rule? It is said that "To give added punch, articles are often dropped in the titles"  Source:   Is there any general rule or reference about dropping articles, especially in academic research papers? surjective immersion $\mathbb{R}^2 \to \mathbb{R}^2$ which is not a diffeomorphism Does there exist a surjective immersion $\mathbb{R}^2 \to \mathbb{R}^2$ which is not a diffeomorphism?  I tried to modify $\exp: \mathbb{C} \to \mathbb{C}$ to be surjective, but I find it hard to preserve the property of being immersion.  I also noticed that if we replace $\mathbb{R}^2$ with $S^2$ or any other compact simply connected manifold, no such immersion exists, because then it would be a covering map (as a local diffeomorphism from compact space, thus proper), but since the manifold is simply connected, it must be a diffeomorphism. Why does $\sum_{k=1}^{\infty}\frac{{\sin(k)}}{k}={\frac{\pi-1}{2}}$? Inspired by  (and far more straightforward, I am guessing), Mathematica tells us that $$\sum_{k=1}^{\infty}\dfrac{{\sin(k)}}{k}$$ converges to $\dfrac{\pi-1}{2}$.   Presumably, this can be derived from the similarity of the Leibniz expansion of $\pi$ $$4\sum_{k=1}^{\infty}\dfrac{(-1)^{k+1}}{2k-1}$$to the expansion of $\sin(x)$ as $$\sum_{k=0}^{\infty}\dfrac{(-1)^k}{(2k+1)!}x^{2k+1},$$ but I can't see how...  Could someone please explain how $\dfrac{\pi-1}{2}$ is arrived at? How do I ignore ampersands in a SQL script running from SQL Plus? I have a SQL script that creates a package with a comment containing an ampersand (&amp;). When I run the script from SQL Plus, I am prompted to enter a substitute value for the string starting with &amp;. How do I disable this feature so that SQL Plus ignores the ampersand? Is there a constraint that restricts my generic method to numeric types? Does a wireless-N (802.11n) network have poor performance when in b/g "mixed" mode? It seems to be an "old" wives tale that, when using a wireless-N router in "mixed mode" to support legacy 802.11b or 802.11g devices, the performance of 802.11n clients will suffer.      claim that when running in mixed-mode, all (some?) N clients run at G speeds.   make the same claim, but say it only happens when a G client is connected.    say N clients run faster, but still run about 30% slower than if the router were in N-only mode, even if there are no legacy B/G clients connected.    claim there is no speed drop for N clients when running on a mixed-mode network.  They say the only issue is that overall network throughput will be lower, because only one client can be transmitting at any time, so some of that transmission time must be shared with the legacy B/G clients running at lower speeds, reducing the overall throughput from what it would be if there were only N clients connected.    So, which is it?  Will running in mixed-mode slow down my network, even if there are no B/G clients?  If I'm running N, will having another client connected at B/G slow me down substantially vs. if they were running N? Emacs: Symbol's value as variable is void