What are the advantages/disadvantages between a (possibly electric) velomobile and a regular bike when in daily use?
are more efficient than ordinary upright bicycles, and  are even more efficient. Then why do we see them so rarely on the road? Is it because they are expensive, or are there some non-financial, significant disadvantages?
What's the @ in front of a string in C#? What happened to the “‑est” and “‑eth” verb suffixes in English? What happened to them, and how were they once used? Straining my mind to sound archaic, I came up with the following:     Dost thou thinkest thou can escape thy sins?   and     Bringeth me mine armor and favorite sword.   I’d like to use these suffixes intelligently, so my questions are: how are ‑est and ‑eth properly appellated in conjugations, and  when and why did they disappear? E: Problem executing scripts APT Update::Post-Invoke-Success error during apt-get update I cannot install any package. It seems the command apt-get update must be run but it throws some errors:  $ sudo apt-get update Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]      Hit:2 http://ve.archive.ubuntu.com/ubuntu xenial InRelease                      Hit:3 http://ve.archive.ubuntu.com/ubuntu xenial-updates InRelease              Hit:4 http://ve.archive.ubuntu.com/ubuntu xenial-backports InRelease            Fetched 102 kB in 23s (4337 B/s)                                                *** Error in `appstreamcli': double free or corruption (fasttop): 0x000000000210f4b0 *** ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7fac8d8317e5] [...] Aborted (core dumped) Reading package lists... Done E: Problem executing scripts APT::Update::Post-Invoke-Success   'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli;   then appstreamcli refresh &gt; /dev/null; fi' E: Sub-process returned an error code Two  have been announced in LoL.  They have an ability that makes them be able to recall together.                                  What are the limits to this ability? Can the 'non-recaller' jump in at the last second and get some kind of instant recall?  Can somebody with the setup to get on PBE test it and tell us what are the limitations of this ability? Why don't websites immediately display their text these days? I've noticed that recently many websites are slow to display their text. Usually, the background, images and so on are going to be loaded, but no text. After some time the text starts appearing here and there (not always all of it at the same time).  It basically works the opposite as it used to, when the text was displayed first, then the images and the rest was loading afterwards. What new technology is creating this issue? Any idea?  Note that I'm on a slow connection, which probably accentuates the problem.  See below for an example - everything's loaded but it takes a few more seconds before the text is finally displayed: How to increase swap space? I have, by default, 250MB of swap space in Ubuntu, and I want to expand it to a larger size. I need 800MB, which I think will be enough to open several applications without having to hit the current limit of swap. I hope someone can help me. I've read the , and I don't get it. I am really interested, but I've read the explanation there a couple of times and I still don't get it how the Duff's device works.  What would a more detailed explanation be? Does removing an application from Software Center do a remove or a purge When I remove an application already installed through the Software Center. Does it remove the app the same way as doing a purge to it (aptitude purge) or does it remove it like a "remove" (aptitude remove). Calculate battery life I would like to know how to calculate battery life when using an LED strip. The LED strip is powered by 8 AA batteries in series. LED Current Draw = 260 mA. LED power consumption: 3.1 W. LED Operating Voltage range: 9-14.8 VDC. Please see attached images for battery datasheet.  This is my calculation, but I'm not sure if it's correct:     Battery Life = (Battery Capacity)/(Load Current) = 2000 mAh /260 mA = 7.7 Hours   This is for one battery, and the lights are powered by 8 batteries, so is the total battery life = (7.7)x(8) = 61.6 hours ? Show that, if $a$ and $h$ are positive numbers, $h &lt; a^2$, then $$\sqrt{a^2 + h}-a &lt; \frac{h}{2a} &lt; a - \sqrt{a^2 - h}$$  I've been working on this problem for about 2 hours now, but I've made no progress. I'm not looking for an answer, but I just need some help to get me started since we didn't practice inequalities this complex in highschool. Thanks.   All I can tell is that we're supposed to take the square root of an expression at some point since one inequality ( h &lt; a^2 ) becomes two.   Edit : Thank you guys for the replies, but I'd appreciate only hints in the future (like Robert Israel) so that I can learn. Regardless, I found a different way to do it, so it's cool :) "Timed Out" error when trying to join server Did your team win the football match yesterday?         The weather was very bad, so we weren't playing.   vs     The weather was very bad, so we didn't play.   Is the first one not correct? Why is it? How do I mount a hibernated NTFS partition? extracting energy from cosmological expansion This question is a more concrete reincarnation of an .  Are there mechanisms to extract energy from the cosmic rate of expansion? putting some extremely long ropes across the universe and extract work from their increase of separation?  assuming this is possible ( i don't see why it would not ), what form would take the back-reaction force? in all physics, every time you extract work from some system by some force, this system will exert a force back. Can we slow down cosmic expansion by variations of these mechanisms? What's the projective limit of these polynomial rings ? Define an inverse system of polynomial rings over a commutative ring $k$ by the canonical projection $k[x_1,...,x_n] \to k[x_1,...,x_m]\;(m&lt; n)$.   Question: What is the projective limit $\varprojlim_n k[x_1,...,x_n]$ ? Why do people buy stocks that pay no dividend? Here is an interesting piece of code that my fellow team members were just having a slightly heated discussion about...    Dim fred As Integer    If True Then fred = 5 : fred = 3 : fred = 6 Else fred = 4 : fred = 2 : fred = 1   After executing the above code snippet, what is the value of fred?  Try not to cheat and debug the code.  This is a highly contrived code example that started out as an example of using the colon with an If statement, but then someone decided to take it upon themselves to proffer a result for fred.  UPDATE: I would not normally write code like this and this snippet only serves as an example. As it so happens, this question originated from a discussion involving the creation of a coding standards document for our team. Counting the number of surjections. overbrace/underbrace but with an arrow instead Is there a similar command to \overbrace{foo}^{bar} but instead of braces, an arrow pointing up/down?  EDIT: Here's a little demonstration of how I'd expect something like this to work:    And possible syntax would be \overarrow{a=b}^{\text{theorem X}} I have a  to which I'd like to add JPEG and PNG images that I generate on the fly.  All the examples I've seen so far in the , specially in the  use ImageIcons.  I'm generating these images as byte arrays, and they are usually larger than the common icon they use in the examples, at 640x480.   Is there any (performance or other) problem in using the ImageIcon class to display an image that size in a JPanel? What's the usual way of doing it? How to add an image to a JPanel without using the ImageIcon class?   Edit: A more careful examination of the tutorials and the API shows that you cannot add an ImageIcon directly to a JPanel. Instead, they achieve the same effect by setting the image as an icon of a JLabel. This just doesn't feel right...