I have a bathtub with a plastic (I think) surface layer which has a small crack in it. The crack is at the bottom, on the inside. Some sort of rusty liquid has now started to ooze out from the crack, which feels less than hygienic.  Before I replace the whole bathtub, I'd like to try to repair the crack. What approach would be the best here? What sealant would be recommended? It obviously needs to be both water-resistant and non-toxic.  I'm thankful for any advice!
Close examination of the floor of my bathtub has revealed a long, thin crack in the bathtub itself.  The bathtub is one of the common plastic-feeling variety (though I am not sure if it is actually a plastic.)  What is the best way to patch this crack?
What is the best format to capture addresses for a universal user-base? What is the best and most usable format to capture address information from a universal user base? I was thinking to have the system detect the country by IP address and have that selected by default, and then state/province droplist would be populated accordingly. But the issue is some countries have states and provinces and some do not. Some have postal codes and some do not. Is there a universal standard to capture complete address info to ensure efficiency for most users?  FYI: I did research on here and while there are some questions that are close, none are about this exact same question (unless I missed something) Can the Force be used to fly? In The Empire Strikes Back Yoda uses the Force to lift Luke's X-Wing out of the water and put it on land.  In Attack of the Clones and in many instances in the second series of The Clone Wars, Anakin (and others) use the Force to jump higher than they could otherwise, or to jump from very high locations, but I don't think I've ever seen the Force used for outright self-levitation.  But if Yoda could lift the X-Wing, shouldn't a strong Jedi be able to lift himself and, essentially, fly with the help of the Force? How to define a bijection between $(0,1)$ and $(0,1]$? How to define a bijection between $(0,1)$ and $(0,1]$?   Or any other open and closed intervals?   If the intervals are both open like $(-1,2)\text{ and }(-5,4)$ I do a cheap trick (don't know if that's how you're supposed to do it): I make a function $f : (-1, 2)\rightarrow (-5, 4)$ of the form $f(x)=mx+b$ by \begin{align*} -5 = f(-1) &amp;= m(-1)+b \\ 4 = f(2) &amp;= m(2) + b \end{align*} Solving for $m$ and $b$ I find $m=3\text{ and }b=-2$ so then $f(x)=3x-2.$  Then I show that $f$ is a bijection by showing that it is injective and surjective. I'm brand new to jQuery and have some experience using Prototype. In Prototype, there is a method to "flash" an element &mdash; ie. briefly highlight it in another color and have it fade back to normal so that the user's eye is drawn to it. Is there such a method in jQuery? I see fadeIn, fadeOut, and animate, but I don't see anything like "flash". Perhaps one of these three can be used with appropriate inputs? Why is a normal subgroup of $G_1\times G_2$ with trivial intersections with $G_1$ and $G_2$ is abelian? Let $G=G_1\times G_2$ be a direct product, and let $H\triangleleft G$ be a normal subgroup such that $H\cap G_1=H\cap G_2=\{1\}.$ Then $H$ is abelian.     I considered the commutators of two elements in $H$, trying to show that it must be $1,$ but I don't see how this works. Any hint is very welcomed and appreciated. Thanks in advance. Flagged emails keep returning and won't synchronize between Apple Mail and Gmail I've had this problem before and can't recall how I managed to fix it last time. I use Apple Mail to access my Gmail and normally flagged emails show up correctly. Starred emails in Gmail equate to flagged emails in Apple Mail and I can unflag an email in either Gmail or Apple Mail and it works.  But now I've got four emails that I can't unflag. They're not flagged in Gmail at all (although they used to be). When I see them in the Flagged folder in Apple Mail, they don't even have flag icons next to them but they're still counted in the number showing next to "Flagged". If I manually re-flag them and then unflag them, they disappear from the Flagged box. But then if I click into Inbox and then back into Flagged they show up again.  Any ideas about how to make these guys disappear for good?! I have a Python  object. What is the best way to subtract one day? Is linear algebra more “fully understood” than other maths disciplines? In , it was discussed how LA is a foundation to other branches of mathematics, be they pure or applied. One answer argued that linear problems are fully understood, and hence a natural target to reduce pretty much anything to.   Now, it's evident enough that such a linearisation, if possible, tends to make hard things easier. Find a Hilbert space hidden in your domain, obtain an orthonormal basis, and bam, any point/state can be described as a mere sequence of numbers, any mapping boils down to a matrix; we have some good theorems for existence of inverses / eigenvectors/exponential objects / etc..  So, LA sure is convenient.  OTOH, it seems unlikely that any nontrivial mathematical system could ever be said to be thoroughly understood. Can't we always find new questions within any such framework that haven't been answered yet? I'm not firm enough with G&ouml;del's incompleteness theorems to judge whether they are relevant here. The first incompleteness theorem says that discrete disciplines like number theory can't be both complete and consistent. Surely this is all the more true for e.g. topology.  Is LA for some reason exempt from such arguments, or does it for some other reason deserve to be called the best understood branch of mathematics? When doing calculations on very large numbers where integral data types such as double or int64 falls short, a separate class to handle such large numbers may be needed.    Does anyone care to offer an efficient algorithm on how best to do this? Xubuntu Dropbox icon fail Plural nouns in nominal compounds I wonder whether there are rules or guidelines regarding plural nouns in nominal compounds. For example a compound university students list. If there are many lists and many universities is it grammatically correct to say universities students lists? Must all elements be in the plural form or can some be left in singular, even though the meaning is plural? I've seen an expression universities student lists; is it correct? Stacks for Unity Launcher I'm looking forward to emulate the behavior of OS X Dock Stacks so that I can have, for instance, one stack for browsers and another one for IDES. People at ask ubuntu are doing a lot of cleaver stuff with custom Launchers and Quicklists (see ). So has anyone figured out how to have stacks in Unity? Anything fancier than a static Quicklist over a dummy folder icon? I cheated on the Disciplined badge, how bad is it? I was looking for badges I didn't have yet, and I saw the Disciplined badge. So I deleted an answer of mine with 3+ votes, and waited. Five minutes later, sweet, a new badge! Then I went to my answer again, and undeleted it. No problem at all, and I keep the badge!   What will happen? Will my badge stay here or not? More generally, what happens when the conditions to get a badge are valid at one time, and then not valid?  Other badge in this case:   Unsung hero - "Zero score accepted answers: more than 10 and 25% of total"   What happens if answers get a vote after getting the badge? Are the badge frequently recalculated? Recently upgraded to Ubuntu 18.10, having two problems.  Easiest to explain: when I open "settings", go to "privacy", select "screen lock", I get the popup window with the screen lock settings, but everything is grayed out:   Second issue: If I step away from the machine for long enough (seems to be 5 minutes), the screen blanks. Hitting a key or moving the mouse wakes it up. But when it wakes up, the only things on the screen are the icon bar at the left and the top bar with status icons on the right end. The rest of the screen is blue, not my normal lock screen image. The screen isn't locked, it doesn't prompt for a password, it's just...blue.  I can move the mouse pointer around the screen, the icons react if I click on one, I can bring up the popup with volume/brightness controls on the top bar. But if the pointer is on the blue background, neither left nor right button clicks do anything.  Now, if I press ctrl-alt-F1 from there, I get a lock screen where I can enter my password. Then I get the blue screen back, but if I press ctrl-alt-F2 I get my normal screen (with running applications) back.  ctrl-alt-F2 without going through the lock screen first does nothing.  I'm not finding anything while searching that matches either of these sets of symptoms. Suggestions? How does the new automatic reference counting mechanism work? What is the remainder when $2^{1990}$ is divided by $1990$? I actually do not have the basic idea on how to approach these type of questions....so please tell me a generalized method about all this too.  It came in RMO, and the question is:  What is the remainder when $2^{1990}$ is divided by $1990$ ? Is it acceptable to use "whose" when referring to an object? Whose is used for people (e.g. "Whose that girl?"), but is it acceptable to use whose for objects too? Is there another word I should use for objects?  To make the question clearer, when I ask "Whose that car?" I am expecting an answer similar to "It's X's car." where X refers to a person. I could say "a man whose opinion I respect." and whose opinion would refer to the opinion of a person. Could I say "the desk whose drawer was broken by my brother"? Should I replace whose with another word? Convergence in probability implies convergence on a subsequence almost surely.  But this means we fix a subsequence, such that $X_{n_k}$ converges for almost every $\omega$, right? The subsequence we pick does not depend on the $\omega$ right? Find $n$ such that $x^2 + x + 1$ is a factor of $(x+1)^n - x^n - 1$. I have to find the form of n i.e. whether n is even or odd and whether it is multiple of 2 or 3 such that:  $x^2 + x + 1$ is a factor of $(x+1)^n - x^n - 1$  What I tried:  $$x^2 + x + 1 = (x + 1)^2 - x $$  also,  $$(x+1)^n-x^n-1= \binom{n}{o}x^n + \binom{n}{1}x^{n-1} + ... + \binom{n}{n-1}x + \binom{n}{n}.1 - x^n - 1$$  $$=\binom{n}{1}x^{n-1} + ... + \binom{n}{n-1}x$$  after getting this far I tried with taking x and n common but still couldn't able to find the right direction.  I need extra hints to solve this. My fiancée and I are looking for a good Caribbean cruise in October and were wondering which islands are best to see and which Cruise line to take?  It seems like a lot of the cruises don't run in this month due to Hurricane season so I'm looking for other good options.  EDIT We'll be travelling in 2012.