FreeBSD 13.1 under Hyper-V on Windows 10 Pro

Question: I am building a new FreeBSD 13.1 Workstation on a Windows 10 machine under Hyper-V.  I have been successful doing this with previous version of FreeBSD, back to releases 6, and previous releases of Windows back to XP Pro.
I have a couple problems with recognizing my mouse.  I am using a Logitech M217 wireless mouse, which I expect to be seen as a Hyper-V mouse.
I expect the mouse to work in any Xorg window manager.   The mouse does work in Xorg under 12.3.  Also the mouse isn't working on the console, outside of Xorg.    It should be able to select/cut/past because 'allscreens_flags="-m on"' is in /etc/rc.conf.  It should work with text-based terminals and in xterm.  It doesn't work with release 13.1 or release 12.3.
In /var/log/console.log, I'm troubled with the following lines;
•   FreeBSD13 kernel: [: mouse: unexpected operator
•   FreeBSD13 kernel: Starting default mousedmoused: unable to open /dev/psm0: No such file or directory
Answer: It seem a know problem, for the device not found, that the FreeBSD team will not work on it.
Bug 221074 - Hyper V Gen 2 install has no mouse
Some comment from the dev;

As I said, no plan for it yet.  The Hyper-V console is not suitable
for X related stuffs.  And again, if you want to use X, use VNC; it is
recommended and works quite well on both gen1 and gen2 Hyper-V.

or, which offer a workaround;

Well, if you do want to stick w/ using the X on the Hyper-V console,
then use gen1 VM, which has an emulated PS2 mouse.  I actually don't
see gen2 VM buys anything useful for desktop users.


How to open Microsoft Excel files?

Question: I would like to read my Microsoft Excel files on my Android device. Is there anything built-in natively? Is there an application for viewing and editing Excel files on Android?
Answer: You can try Documents To Go. You can create, edit, and view MS Word, Excel, PowerPoint, and even PDF docs.
As a free alternative, you can upload your Excel docs to Google Docs and use the free GDocs app.
Comment: Note that you can now, you should now be able to edit from a mobile at the website at http://docs.google.com or by installing the official app https://market.android.com/details?id=com.google.android.apps.docs More info at http://www.google.com/mobile/docs/
Comment: Note that you cannot edit Google Docs from an Android phone.
Answer: Here are two ideas:

upload it to google docs (you can do it from the browser) and view it there.
use an office application such as OpenOffice, OfficeSuite or QuickOffice or Mobile Document Viewer
Answer: My favorite app for this is OfficeSuite Pro but I got it when it was the free app of the day, so I can understand not wanting to pay $14.99... it is a great program though!
Answer: OfficeSuite is a great app for viewing and editing documents. There are two versions one as a Viewer (free), the other as a Pro (payable) version. There is also a trial version of the Pro version, so you could try it out if you decide to buy it.

What you get:

File browser
Text document module
Spreadsheet module
Presentation module
PDF Reader
Email reader

Supported formats:

Text format - DOC and DOCX, DOCM, RTF, TXT, LOG
Spreadsheet - XLS, XLSX, XLSM and CSV
Presentation - PPT, PPTX, PPS, PPSX, PPTM and PPSM
Other formats - PDF, EML, ZIP

Bonus:

OfficeSuite Pro is the only Android mobile office application that allows opening of password protected documents (taken from the Google Play site)
Answer: You could try WPS Office. It's free and I find it very useful.
Here is a list of features highlighted on official page:
Spreadsheets:

Fully compatible with Microsoft Excel
Includes dozens of formula and function shortcuts
Supports pivot tables, freeze frames, sorting, table styles and more
Insert charts, including bar, pie, line and column
Edit cell categories (number, text, percentage, etc.)
Answer: Is AndrOpen Office any good?
Supposedly its OpenOffice made for Android.
Comment: While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference.  Link-only answers can become invalid if the linked page changes. - [From Review](/review/late-answers/252066)
Answer: If merely viewing is your requirement, something like XODO Docs would do the best for you
For both editing and reading, the official Microsoft Excel for Android would be the best choice

How to open Microsoft Excel files?


Why is hydrolox used for first stages?

Question: I understand that hydrolox has the highest specific impulse of any conventionally used propellant, but its density is so much lower that you would get more impulse in Newton seconds out of the same volume of kerolox. The density of kerolox is about 0.81–1.02 kg/L[1], while the density of hydrolox is about 0.36 kg/L at a 6:1 LOX/LH2 ratio[2], about 35-45% that of the former. In order to have the same impulse for unit volume as RP-1, hydrogen would need to have 2.24 to 2.82 its specific impulse, which it doesn't. Typical hydrogen engines seem to have about 50% higher specific impulse than typical RP-1 engines at sea level. So wouldn't they get better results from putting RP-1 in their first stages instead of hydrogen?
1
2
Comment: Could you list several first stages using hydrolox?
Answer: The problem with your analysis is that impulse per unit of volume isn't the right metric.
Impulse is measured in units of force times time. Acceleration is measured in units of force divided by mass, not by volume. A rocket with a given volume of RP-1+LOX is much more massive than a rocket with the same volume of hydrogen+LOX; a given total impulse will yield less total change in velocity for the RP-1 rocket.
The increased volume of a hydrogen rocket does incur a slight mass penalty due to the weight of the empty tank and additional insulation needed, as well as a physically larger rocket engine to deliver equivalent thrust, as well as a drag penalty, so the hydrogen advantage is less than the specific impulse difference, but hydrogen still has a significant advantage, ton for ton. There's more discussion of the topic on this older QA.
However, your question's premise is faulty: pure hydrogen-LOX first stages are a rarity in modern orbital launchers -- Delta IV Heavy is the only operational one I can think of. Much more common is an RP-1 or RG-1 first stage (Soyuz, Falcon 9, Atlas V), or solid rocket boosters paired with hydrogen "sustainers" (Ariane 5, SLS). The reason for this is mainly cost. Hydrogen engines tend to be more difficult to engineer than equivalent-thrust kerosene engines, and very large first stages increase construction and infrastructure costs, while solid boosters tend to be very cheap and compact for their thrust. In the solid-booster/hydrogen-sustainer cases the hydrogen engine functions as a second stage, even though it may be ignited on the ground.
Answer: Because the Shuttle set a precedent, and we have spent a generation unwinding that precedent. Or, are still spending time unwinding, because of institutional/fiscal inertia.
The point of the Shuttle was to be reusable, and the fewer stages, the more straightforward was reuse, even if those stages were more complicated . Hence, hydrogen. Due to Nixon's BoB (Bureau of the Budget), the Shuttle program had its goalposts moved, fiscally. The result was the ~2.5 stage design, with solid boosters as 'stage 1' (core stage was actually stage 2 but lit early, as Russell states). The solids had lower upfront cost, and legislators would vote for that.
Shuttle led, most directly, to Energia/Buran, but also Ariane 5 (not Arianes 1-4, which kept LH2 to the upper stage as you noted), H-II, and to lesser extents their Indian and Chinese equivalents. Less directly, Delta IV used LH2 because there was a hydrogen engine available, and someone decided to go for it (where Lockheed Martin and Alliant did not, for their own reasons).
We (…mostly, see below) are now healing from the damage of the Shuttle. First, segmented solids had to go. In particular, H-II solids were never that large in the first place, and their joints were unnecessary cost, mass, failure modes, etc. I suspect/speculate that managers wanted to show segment technology, as 'keeping up with the joneses', including national pride. H-IIA then went to short, squat, monolithic boosters to be more competitive- pride has turned out to cost many a person many a million. Ariane 6 will also unwind the mistake of segmented solids… but SLS will not. It will (eventually?) fly more segments, because that will cost many a person many a million more.
Now the core stages… ULA and SpaceX are going to methane fuel because they get it, like you. Blue Origin, too. Ariane 6 will still use LH2, because they won't spend the money on a totally new engine. Safran figures upgrading is a better deal. SLS keeps LH2, not because they don't get it, but because 'it' isn't what you think it is. The point of SLS is to keep rich people rich: sending new pork to the districts that had been getting Shuttle pork.

Why is hydrolox used for first stages?


How to order a group of ships to protect a specific area?

Question: I just started playing Homeworld (Classic) and was wondering if there were any commands that could help with having a group of ships protect a specific area and attack anything that enters range of it? I know they added that to remastered but I was wondering if I was just missing something, or if thats just part of the gameplay is managing who your attacking when.
Answer: Simply order your ships to move to the intended coordinates and leave them on the default Defensive Stance known as 'Neutral'. They will attack nearby enemies and try to dodge enemy weapons fire. Note; they will chase enemies if you put them on 'Aggressive' and not fire back on 'Evasive'.
The unit AI is of course fairly limited as is standard for an RTS. You may have better results micromanaging units especially against a human player.


Parking in Oxford

Question: I'll visiting Oxford for the day (maybe four our five hours), on a weekday in the last week of July. I'll be driving a rented car, coming from London, on my way to the North of Britain. Where would it be most convenient to leave the car while visiting the main highlights? (university campus, library, etc)
Comment: I decided I'll use the park and ride options (either Pear tree or Redbridge, which have the most frequent buses). Price is  £2 for the day for parking, and bus  £4.80 for two adults round trip.
Answer: Your best bet for Oxford is to not have a car! Really...
There are a handful of parking sites in the city centre, but they're very expensive, and often full. Especially at the moment with all the building works for the expanded Westgate Centre, which means that the main shoppers carpark is a building site.
If you really must drive in, and don't mind traffic jams, loads of cyclists everywhere, and a fair chance of getting a fine in the post after you get confused and drive down a bus+taxi+cyclist only street (of which there are many), then:

From the West, there's temporary shoppers parking at the Ice Rink on Oxpens (10 mins walk from the centre) that isn't always full, and the Worcester Street carkpark (5 mins from the centre) that is full most of the day
From the North, there is parking on St Giles (central) but that's almost always full, and Gloucester Green car park (ditto), otherwise you can slog in traffic round to the ice rink
From the East, there's basically nothing - you have no hope most of the day getting a space on Broad Street for example
From the south, the ice rink

Oh, and those are all council run, expect to spend £3-£4/hour. Full details on the city council website
There is a handful (and by that I mean fewer than 10) of free spaces on streets near the centre, all 1 hour or 30 minute limits. Unless you're happy with a 25+ minute walk (map of permit parking zones - you need to go out beyond those), you can't park for free
The recommended option is to use the Park and Rides. These are big car parks around the edge of the city, with regular quick buses taking you right into the city centre. There is at least one on every major route into the city, sometimes more than one. No need to worry about narrow roads, no parking, fines for using bus lanes etc, easy!
Otherwise, the railway station is a few minutes walk from the city centre, the bus/coach station is even closer. Why not take a bus / coach / train to the city instead?
About your only central free parking spots are for bicycles, motorbikes and canal barges
.
Oh, and one other thing. You say visiting the main highlights? (university campus, library, etc) - You probably need to read up a bit more on Oxford! There's isn't a library, there's several famous ones, and about a hundred in total! Also, Oxford University doesn't have a campus, it has a city. Where other universities might have space between their buildings, Oxford has bits of city, including lots of bits of "boring old city" that are older than some countries...
Comment: @AlejandroVD Depends what you're into - we have several amazing but quite different free museums, old buildings, old churches, libraries, great gardens, hidden away little spots, picturesque views etc! [Wikivoyage has quite a good guide to what there is](https://en.wikivoyage.org/wiki/Oxford)
Comment: Thanks for you answer! By "main higlights" I ment basically what tripadvisor lists here: https://www.tripadvisor.com/Attractions-g186361-Activities-Oxford_Oxfordshire_England.html
I'll definitely research about the Park and Rides, probably it's the best bet.
Comment: Note that most of the things on that list are free, despite prices that TripAdvisor shows! Also note that the "University" isn't one building, it's several hundred, much of them in specific colleges
Comment: I know.. sorry about my "dumb tourist" tone :-) I'll do more research to try to make the most of my quick visit. BTW, if you happen to know a more reliable site than Tripadvisor for "best things to visit in Oxford" please let me know. Thanks again!
Comment: how much is "very expensive"?
Comment: @JoeBlow Varies exactly by carpark, exact prices can be found on the [council website](https://www.oxford.gov.uk/homepage/41/car_parks_in_oxford), but it'll be about 20 quid for a trip of the OP's desired length
Comment: OP seems like they are on a driving tour of the of the UK, or stopping off at Oxford on the way to something else up north, so *not taking the car* is probably not an option, so P&R it would be.
Answer: What counts are "most convenient" would be a value judgement, but I can present some options.
Oxford's traffic and parking is in general pretty bad. July should be a bit quieter, because of summer holidays, but a weekday does mean that workers will be using most available parking space.
Your lowest-stress option is probably to use a park-and-ride facility. With these, you park your car in a large, easy-to-access car park outside of the city, and then get a bus in to the town centre. The prices vary depending on which car park you use - Pear Tree and Thornbridge both mention being accessible from the M40, which fits with your itinerary.
Somewhat unusually,  payment for parking and bus is apparently separate in Oxford. You can find more about the bus services (and fares) on the OxfordBus site.
If you wish to park closer to the city centre, it seems that most parking is operated by Oxford council. If you are able to arrive and leave outside of peak commuter times, this might not be too bad an option. You can find out more about the council parks (and rules) on the Oxford parking site. One notable option is to reserve in advance a permit at the Oxpens site, guaranteeing you a space - although it is about 20 minutes walk from the University.
I don't know what the options are with regards to on-street parking, especially on the out-of-centre side of the University, but from what friends and family have told me of driving and parking in Oxford, I'd be surprised if there was much opportunity. Still, you could drive around having a look if you want. Just pay careful attention to signage regard availability and time limitations to avoid a substantial fine.
Comment: My boyfriend, who studied in Oxford and still visits at times does not even think about bringing his car into the city during the day, it is park and ride for him.
Comment: Thanks for your answer! I saw there is a parking lot in a park, "Walton Well Road Car Park". It is about a mile away from the University, but I guess we  can walk there, weather permitting. Do know if it is used a lot on week days?
Comment: It's pretty rammed most of the time, as it's popular with people working in Jericho + those who live in Jericho who have no parking + people walking on Port Meadow.
Comment: @Gagravarr appears to have better local knowledge than me, but assume that anywhere at all central will be full during the working day. Note that queues to get in to Oxford can be >1 hour in the morning rush.
Comment: I walked past the Worcester Street carpark at lunch, no spare spaces and people waiting for any to become free. Expect most to be at least that bad!

Parking in Oxford


Why is the joining fatal for some?

Question: As we all know the joining can be fatal for some. The concoction a recruit drinks is a special blend of darkspawn blood, lyrium AND Archdemon blood, so it is no wonder people die, but what attributes affect the survivability rate? Why do some people die while others survive?
Answer: As far as I know, there is no explanation for why certain people survive and others don't.
The implication is that people are affected by the poisonous nature of the darkspawn blood different, much like humans in the real world are affected by poisons, venoms, and even many pathogens differently. Those people who are not "strong" enough (mentally, physically, whatever) succumb to the joining and die.
But exactly what that "strength" is, is never mentioned. It's even possible the Wardens don't actually know the reason. Certainly none of the Wardens we see during the ceremony say anything like "if you are pure of heart, then you will survive", or anything like that.
In fact, I'd assume that if they did know what it was that let some survive and others die, they'd probably work harder to weed out the unsuitable candidates long before they got to the Joining.
Comment: Good point that they'd probably not select candidates likely to die if they knew what the determining factors were. When asked about the Joining one of the Warden's say that they don't mention it when recruiting because then no one would want to become a Warden.
Comment: Good points. I'd like to know more about the very first joining, is there anything that covers that topic in detail? besides the in-game codex.
Answer: The common connection seems to be that those who are selected are generally more fit and hardy, and by and large seem to also possess a bit of the whole "the ends justify the means" attitude, though Alistair would be one of the exceptions as far as I can see. However, we don't have a definitive answer.
For example, I believe World of Thedas Volume 1 mentions that while there have been rumors of more Qunari/Tal-Vashoth attempting the joining, there is no confirmation if they survive or not. While this could be attributed to the rumors and headcanons about their blood, it is hard to deny that most of their species are hardier and more fit than most in Thedas. And with their mindset, they would certainly make great recruits, but we don't know what happens with them.
Overall, it's not very clear. But it will probably not be answered, as it leaves open a lot of room for interpretation and would take away a bit of the mystery of the Wardens.
Comment: This answer would be even better if you could dig up direct quotes from World of Thedas Volume 1, instead of relying on you recollection.

Why is the joining fatal for some?


At what rpm does the tip of a 54" propeller start to incur mach losses?

Question: At what rpm does the tip of a 54 inches propeller start to incur mach losses? The max rpm of my engine is 3600.
Comment: I think mach loss requires a forward speed as well as a tip velocity to calculate. At rest, your 54" diameter prop would need to be rotating at ~4800 rpm for the tips to approach mach 1...
Answer: A 54 inch propeller would start to incur efficiency loss at approximately 4300 rpm.
At 4300 rpm a 54 inch propeller would have a tip speed of 691 mph which, relative to the 767 mph speed of sound, is about the maximum which still allows propeller efficiency.
You can calculate the variables using this tool: WarpDriveProps.com Propeller Tip Speed Calculator
Comment: Flight speed and disk loading should also be considered. Your number looks right for a lightly loaded prop in a ground test.
Comment: Can you explain why 691 is "just below" 767? Is that the 0.92 comment from the embedded screenshot?
Comment: Yes, "just below" was taken from the screenshot and was poor wording on my part. I edited the answer. Thanks.
Answer: Assuming you have properly sized the prop for mission and power, peak performance is 0.8-0.9 mach as shown in comments and other answers. Aim low if your prop has fat or blunt tips. You would normally also consider advance ratio (helix) but in a slower aircraft this won't have much effect.
If you consider all losses (not just mach) you might ask what prop speed gives peak efficiency, and it is slower. I usually consider 0.65-0.75 mach a better target because efficiency gives me range. It is also quieter. Every prop is different but here are a couple of examples. They are RC props because data was available, and the curves give indications. I wouldn't believe any exact numbers.
Comment: These are two particular props and not representative of every possible configuration. I'd be very interested in a Thunderscreech efficiency chart if you have one. 450kt in a prop plane is impressive, even if it used 6k shp to get a single seater there.
Comment: Seeing as the efficiency in that graph seems to go to zero around Mach 0.8 - 0.9, how are supersonic propellers (such as that in the Thunderscreech) able to produce any thrust at all?
Answer: .....at the first sign of motion?  Seriously, the instant a propeller blade - like any object moving through a fluid - starts moving, it's creating drag as it takes energy to displace the fluid in its path of motion.  That applies to the entire surface of the prop, not just the tip.
Comment: The question has been edited to be (IMO) a completely different one; this is a great answer for the original.
Comment: Yes it was,had to edit the question cos' I didn't ask as intended at first.


Does the union of the subcomplexes of $X$ that contain a given subcomplex and whose inclusion in $X$ is trivial on $\pi_1$, have trivial $\pi_1$?

Question: Let $X$ be a simplicial complex and let $A \subset X$ be a contractible subcomplex on the same set of vertices as $X$. Is it true that the union $$\bigcup C$$ taken over all complexes $A \subset C \subset X$ whose inclusion in $X$ induces the trivial map on fundamental groups, has trivial fundamental group?
Comment: (Let me just note a subtle point of the above argument: in order to use the van Kampen theorem, the pieces we are unioning must have a common basepoint. This is ensured by the condition that $A$ contain all the vertices.)
Comment: Note that by the van Kampen theorem, the set of "$C$"'s is closed under binary unions. It follows that the set of "$C$"'s is directed under inclusion, and therefore  since $\pi_1$ commutes with directed unions, we have that $\pi_1(\bigcup C) \to \pi_1(X)$ is 0, i.e. $\bigcup C$ is itself a "$C$". In other words, the set of "$C$"'s has a unique maximal element, given by $\bigcup C$.
Comment: And moreover, the "$C$"'s are closed under subcomplexes containing $A$, so a subcomplex of $X$ is a "$C$" if and only if it is a subcomplex of $\bigcup C$ containing $A$.
Comment: What you have written is correct. I should also note that there is a connection with covering complexes: The union $\bigcup C$ is equal to the full subcomplex of the universal covering complex $\tilde{X}$ of $X$ on the vertices in the image of a lift of $A$ to $\tilde{X}$.
Answer: I think it does not. Begin with $A$ a path $\{1,2\},\{2,3\},\{3,4\},\{4,5\}$. To construct $X$, add an edge $\{1,3\}$ and triangles $\{1,2,5\},\{1,3,5\},\{2,3,5\}$ to $A$.
$A$ is contractible. If $C$ contains $A$ and its image in $X$ has trivial fundamental group, it does not contain any of the edges $\{1,5\},\{2,5\},\{3,5\}$: for instance, if it contains $\{3,5\}$, then it contains the closed loop $3\to 4 \to 5 \to 3$ (a triangle) but there is no triangle containing the vertex $4$, so there is no nullhomotopy.
The path $1\to 2\to 3\to 1$ is contractible in $X$: the union of triangles we added is a disk which bounds it. Thus $\bigcup C$ of the question is just $A \cup \{1,3\}$. It contains none of the triangles of the complex: they each contain one of the forbidden edges $\{i,5\}$ where $i\in \{1,2,3\}$. So the path $1\to 2\to 3$ is not contractible in $\bigcup C$.
Comment: If I'm drawing it right, it looks to me like $X$ is basically a sphere with two discs removed, so homotopy equivalent to $S^1$, right? In addition to the edges you mention, the only other edges are $\{2,5\}$ and $\{3,5\}$ and $\{1,5\}$, right? It looks to me like $1 \to 2 \to 3 \to 1$ is _not_ contractible -- it looks like we would need a triangle $\{3,4,5\}$ to make it contractible. So it looks to me like $\bigcup C = A$ is contractible.
Comment: @TimCampion The union of the triangles in $X$ is a disk with boundary path $1\to 2 \to 3\to 1$. In fact, it is a cone over this path, and $5$ is the apex.
I don't think it's a sphere with two discs removed: the link of $5$ is homeomorphic $S^1 \sqcup \mathrm\{pt\}$ (if this is to be a subspace of a 2-manifold, the link must be homeomorphic to a subspace of $S^1$).
You are correct about the other edges: to other readers, these come from the three triangles we've added.
Comment: @GevaYashfe Thanks, I think I see now. $X$ is more like a sphere with a disc removed (the "missing triangle" $\{1, 2 , 3\}$) and a loop added (the two edges $\{3 , 4 \},\{4, 5\}$), which comes out homotopy equivalent to $S^1$ but  in a different way. (My mistake before was that I was drawing the triangle $\{2,3,5\}$ as though the $\{3,5\}$ edge were the nonexistent "composite edge" $\{3,4,5\}$ -- too much category theory for me!) By the way, why do you say "add an edge $\{1,3\}$" (twice!) at the beginning? That edge comes anyway when the triangle $\{1,3,5\}$ is added.
Comment: @TimCampion That makes sense. I think about simplicial complexes a lot, but my first attempt at an answer was mistaken as well.
Thanks for spotting the redundant $\{1,3\}$s. The first one was probably a mistake I made while rephrasing part of the answer. But I didn't notice that the second is redundant as well! I guess I was thinking about it in two steps: first add the "interesting" cycle $1\to 2\to 3$ to $A$, and then add the disc to fill it. I think I'll leave the second $\{1,3\}$ as it is.
Answer: Take $X$ to be a circle with three 0-simplices and three 1-simplices. Fix a point, then the union of all contractible subcomplexes containing that point is the whole circle.
EDIT : taking into account the fact that $A$ needs to contain all vertices.
I think it is true. At some point the proof isn't totally formal but I think it can be made rigorous. Let $Y$ be the union of the subcomplexes $C$ with a trivial inclusion in fundamental group and containing $A$, and take a map $f:S^1\to Y$. By some strong version of simplicial approximation you can suppose that there is a simplicial structure on $S^1$ such that $f$ is homotopic to a simplicial inclusion. Take your chosen basepoint of $S^1$,  $*$, and run over the circle clockwise. The images of $f$ begin in some subcomplex $C$ of the union and you eventually quit it. Consider first point of the circle after which you quit $C$, say $p$. Then $f(*)$ and $f(p)$ can be linked by a path in $A$ because it contains all the points and is contractible. This path is also in $C$. Glue this path and the path drawn by $f$ from $*$ to $p$, then it makes a loop on $C$ which is trivial in the fundamental group of the whole space $X$. So, $f$ is homotopic in $X$ to the same loop but where you have replace the path from $f(*)$ to $f(p)$ by your chosen path in $A$. But we rather want a homotopy in $Y$. Nevermind : the homotopy can be simplicial approximated in the 2-skeleton of $X$ and you can add to $C$ the 2-cells needed for the homotopy. This part is less formal but I think it can be written well. Do that by induction until you run out of vertices of $S^1$, and then the new $f$ has values in $A$ so is nulhomotopic.
Comment: But their intersection is empty. I required that all complexes in the union contain a given contractible subcomplex $A$. I also forgot to mention that the subcomplex $A$ is on the same set of vertices as $X$. I have now added that to the question.
Comment: If you take a tetrahedron with the standard cell decomposition, and take $A$ to be a point and all 1-simplices touching the point, I think it makes a counter-example
Comment: Ok my bad, then take a cell structure on the circle with 3 points and 3 lines. Fix a point, then the union of the contractible simplices containing that point is the whole circle. I'm correcting that in the main answer.
Comment: You are correct, but I forgot to mention that the subcomplex $A$ should have the same set of vertices as $X$. I have now added that to the main question.
Comment: But the tetrahedron has trivial fundamental group, so it would be part of the union?
Comment: Oh I mistakenly replaced the statements about the pi1 by contractibility, sorry.
Comment: Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/115140/discussion-between-eryb-and-elidiot).


Tibetan Buddhist Deities

Question: Are Tibetan Buddhist Deities real (external)? I've been to two Medicine Buddha pujas and a Tsog offering and I can't figure out if it's all just hocus pocus. Professor Tom Yarnell's definition of Deity yogas as "ascertaining emptiness as arising in or experienced as the form of a deity" (not sure I got it right - it's from  a Tibet House video ("what is Deity Yoga?")I'm trying to understand. Thanks!
Answer: No, the Tibetan deities are not real in that ontological sense. There are two ways I will answer your question. One is to think of these deities as the personified qualities. To thus humanize them serves to make them a model and aspire to become them, aka, those qualities.
Second, thinking along your lines of Yarnell's definition: Ascertaining emptiness is synonymous to saying that one is able to see the mereological relationship in terms of dependent origination. And what does dependent origination conclude to a question about appearances and reality? What appears is not how it is. Therefore, in ascertaining emptiness in the form of deity is to take that as the object of meditation whose emptiness is analytically established and thus not revere something doubly illusory but to know it as illusory and yet use that to arrive at analytical conclusions.
Hope this helps.
As to the implicit question of offerings, those rituals have their uses. What one may think about an activity might well be hocus pocus but that might not be a characteristic of that activity to begin with!
Comment: This is an excellent answer

Tibetan Buddhist Deities


Diffeomorphism groups of orbifolds

Question: A lot is known about geometric and topological properties of diffeomorphism groups of surfaces (here, I am mainly thinking about the work of Smale and Eells-Elworthy). Is there anything known for orbisurfaces ? My first guess would be that many of these groups must have contractible components since singular points impose extra conditions somewhat similar to fixed points. Is there a good reference on this topic ?
Answer: The result you want can be found in the following paper:
MR0955816 (89h:30028)
Earle, Clifford J.(1-CRNL); McMullen, Curt(1-MSRI)
Quasiconformal isotopies. Holomorphic functions and moduli, Vol. I (Berkeley, CA, 1986), 143--154,
Math. Sci. Res. Inst. Publ., 10, Springer, New York, 1988.
What they prove is actually pretty remarkable.  Namely, let $S$ be a hyperbolic surface.  Then there is a family $\phi_t$ of self-maps of $\text{Diff}^{0}(S)$ such that $\phi_0$ is the identity, such that $\phi_1$ is the constant map taking each diffeomorphism to the identity diffeomorphism, and such if $f \in \text{Diff}^0(S)$ commutes with a finite order diffeomorphism $g$ of $S$, then $\phi_t(f)$ also commutes with $g$ for all $t$.  In other words, you can contract $\text{Diff}^0(S)$ in way that doesn't break any symmetries.
Now assume that $\Sigma = S / \Gamma$ is a good hyperbolic orbifold, where $\Gamma$ is a finite group of diffeomorphisms of $S$.  The identity component of the orbifold diffeomorphism group of $\Sigma$ is then homeomorphic to
$$\text{Diff}^{0}(S,\Gamma) := \langle f \in \text{Diff}^{0}(S)\ |\ gfg^{-1}=f\ \text{for all}\ g \in \Gamma \rangle \subset \text{Diff}^{0}(S)$$
The null-homotopy $\phi_t$ preserves $\text{Diff}^{0}(S,\Gamma)$, so it is contractible.
(EDIT : I made a slight fix to the definition of the orbifold diffeomorphism above.  It doesn't change the argument.  Thanks to Tom Church for pointing it out to me!).
Comment: Thanks for this quick and illuminating answer. Do you know if some of those results extend to non-hyperbolic orbifolds ?
Comment: They fail even in the classical case for non-hyperbolic surfaces (for instance, for the sphere or the torus).
Comment: Well, my question was badly formulated. Here's a second try: Do you know any results on the homotopy type of diffeomorphism groups of non-hyperbolic orbisurfaces (à la Smale), regardless of the techniques used ?
Comment: Sorry, I'm not aware of any such results.  I'd be interesting in hearing about any ones that you find!

Diffeomorphism groups of orbifolds


Could such a galvanic cell exist

Question: Imagine I have a galvanic cell where in one half cell there is a lump of potassium metal and molten KOH electrolyte, and in the other an inert electrode, as well as a molten KOH and the less active metal salt dissolved in it. Would the fact that the more active metal cations are present in the reduction half cell interrupt the process?
Comment: The key question you are trying to formulate is that would potassium metal reduce molten salt of a less active element or not. If it can, the galvanic cell will work. What salt do you have in mind?
Answer: The potassium ions in the reduction half-cell are inert, merely serving as part of the electrolyte.  The are no problem at all.  Indeed, you actually need to allow for the passage of more potassium ions through your separator, to balance the potassium metal that's dissolving and make up for the cations being plated out at the cathode.

Could such a galvanic cell exist


Morton Brown's theorem

Question: Suppose that a topological space $X$ is the union of an increasing sequence of open subsets $U_i$c each of which is homeomorphic to the Euclidean space $\mathbb{R}^n$. How does one show that $X$ is homeomorphic to $\mathbb{R}^n$? I am unable to prove it in the case $n=2$. This is Dieudonne's problem.
Answer: This should answer your question: http://arxiv.org/pdf/math/0404372v1.pdf.

Morton Brown's theorem


Does Google App Engine Java support Hot Deployment in Eclipse?

Question: It doesn't seem to do this by default, which is pretty shocking to me given all the other stuff they've set up to make development easy. Is there a way to enable this? If not, anybody know why it isn't supported?
Answer: There is JRebel that can help you with this http://englove.blogspot.com/2010/09/appengine-hot-deploy-on-mac.html
But using JRebel i had troubles with GWT in Development Mode.
BUt, there is a simplier way to do it. You can have hot deploy of your server clases if you debug your application in Eclipse.
Debug As -> Web Application
That's all! :)
Comment: I can confirm that debugging the app is working for me. Thanks a bunch, nacho3d!
Answer: This is an open feature request on the App Engine Issue Tracker. You should vote on it there.
FWIW, it does work with JSP as expected (they get invalidated and recompiled when you update them).
Answer: I realized that local server reloads when I modify and save the appengine-web.xml file, so i created a build.xml file with this instructions and runs from eclipse+ant, so I have a hot deploy
<?xml version="1.0"?>

<project default="main" basedir=".">
<property name="appengine" location="${basedir}/war/WEB-INF/appengine-web.xml" />

<target name="main">
    <echo message="REINICIANDO SERVIDOR LOCAL ${appengine}" />
    <touch file="${appengine}" />
</target>

</project>

Answer: I work with App Engine 1.9.2, and it is already working not only for JSPs, but Servlets and Java code as well.
If your project is Maven-based, and you start your server with mvn appengine:devserver, after modifying some code, all you need to do is
mvn package

and refresh the page in your browser.


Smooth brush destroys my mesh

Question: So i'm sculpting and, sometimes, specially after i made a big change in the surface with any other brush, the smooth brush completely destroys the geometry that was there. This only happens after i've set dynotopo and changed the mesh, and if i turn it off, it stills creates the same problem.
Every now and then if i enlarge the radius of the brush, it fixes it, but usually i have to take out any hard edge or lower a big bump that i made before and that seemed to have caused it. The weird thing is that it acts like that for the whole mesh and not just specific parts, and that sometimes it only happens when using my graphic tablet(as in the gif), but other times with both the tablet and the mouse.
Comment: Check your normals and could there be another layer of verticies behind the mesh we can see in your video? Try turning down the strength of the Smooth brush. Let us know how you get on.
Comment: This is really silly but, turns out, my pen tablet has the option to swith from 'add' to 'substract', to essentially do the opposite of what the brush does, whenerver this happened was because i had it in 'substract' mode, i didn't realize this because in previous versions of Blender it 'shift' to smooth always smoothed stuff, not anymore it seems :p.
Comment: please add that as an answer so other can find it and well done on working out what the issue was.
Answer: It turns out, my pen tablet has the option to switch from Add to Substract, to do the opposite of what the brush was doing.
Whenever this happened was because I had it in substract mode, I didn't realize this because, in previous versions of Blender, Shift to smooth always smoothed stuff, but not anymore it seems.
Other person with similar problem: my tablet lists it as "pen or eraser" mode
Answer: Had the same problem. For me pressing CTRL toggles between add/subtract for as long as I hold down CTRL. Alternatively, you can also click the + or - in the top toolbar to switch between add/subtract smooth if CTRL doesn't work.

Smooth brush destroys my mesh


Feeling amazing or amazed?

Question: Is there anything wrong with saying "I was feeling amazing at the party with all my friends around"? Is it grammatically incorrect? Should this be said some other way?
Comment: It depends on the meaning you want your sentence to have. Either way is grammatical, but they have different implications.
Answer: It's important to note that many people use "amazing" as slang to mean "very good," "awesome," "excellent" etc.  But other forms of the verb "amaze" are taken literally.
So your two sentences are both grammatical, but have different meanings because of the colloquial meaning of "amazing"

I was feeling amazing at the party ...

means that you were feeling exceptionally good while at the party.  The party likely put you in high spirits.

I was feeling amazed at the party...

means that you literally were amazed while at the party.  Perhaps the party was a lot better than you expected, and you were impressed by the quality.  Or maybe you were amazed by a illusionist/magic show.
Answer: I was feeling amazing at the party with all my friends.
I was feeling amazed at the party with all my friends.
You usually use the adjective amazing like many other adjectives ending with "ing" to express the characteristic of somebody or something such as:
His performance was quite amazing.
He is an amazing player.
The meal was amazing.
In these sentences, the amazing means very surprising.  In spoken English, it also means great, wonderful.
I think the adjective amazing in the sentence I was feeling amazing has been used in the latter sense that I was feeling very good/great at the party.
As for the adjective amazed like many adjectives ending with "ed", it's used to express a feeting, The adjective amazed means extremely surprised.  So the sentence means that I was feeling extremely surprised at the party.

Feeling amazing or amazed?


Do spouses of UK citizens who hold a non-EU passport have to apply for a Schengen VIsa now

Question: When UK was part of the EU, non EU spouses of UK citizens were allowed to travel to the EU without a visa. Now post-Brexit I take it that this is not the case and she will need to apply for a Schengen visa?
Answer: The short-stay visa requirement in the Schengen area was always based on citizenship. If your spouse comes from the 60+ countries listed in the so-called "annex II" (covering most of the Americas, non-EU Europe, UAE, Japan, South-Korea, Malaysia…), they can visit visa-free. Otherwise, they need a visa. That was the case before Brexit and will continue to be the case. The same rule applies to third-country nationals who do not belong to the family of an EU citizen.
What changed are the rules around getting that visa. For people covered by the EU freedom of movement (including the family of British citizens before Brexit), that visa must be free of charge and valid reasons to refuse a visa are very limited. For other people (including most British citizens' spouses after Brexit), you have to pay a visa fee and submit a lot more documentation (e.g. on your financial situation).
There is an additional exemption for spouses of EU citizens residing in another EU country with a residence card as a "member of the family of an EU citizen" (article 10 or 20 card, it should explicitely say so on the card). In that case, it's not necessary to apply for a visa for a short visit, even if you come from a country whose citizens usually need one. The exemption should still apply to British citizens who settled in the EU before January 2021 and their family but otherwise ceased to be relevant after Brexit.


BLS signature java implementation needed (if possible, along with some example code)

Question: I need to sign a string with the shortest digest possible using regular certificate like X.509. As far as I understand, I will have to transform the string to the sequence of bytes, then sign. After that I need to transform signature to the string also (so it can be passed from one human to another). I found out here that BLS algorithm is great for that and I want to try it out. Would you recommend some java implementation of it (would be great to have a code example along with that so I can avoid messing up with string to byte and vice versa transformings)?
Answer: The Boneh-Lynn-Shacham signature scheme works only in special elliptic curves that support efficient pairing computations. This is not something that you somehow add on top of an existing signature; it is a signature algorithm in its own right, that uses its own kind of public/private key pairs. If you want something that works with X.509, then you need a public key that can be encoded as part of an X.509 certificate. Currently, there is no defined format for a public key appropriate for BLS(*); X.509 is an open-ended standard so you could conceptually define your own format and make your own implementation, but:

This is an endeavour of considerable scope. It would require from you thorough knowledge of ASN.1 and DER encoding, elliptic curves, and pairings over elliptic curves (which is a plunge into rather hairy mathematics); and also strong skills at implementing cryptographic algorithms.
Since that would be your definition, there would be no interoperability with the implementation of anybody else, so your signatures would be verifiable only with your own software. At that point, why bother with X.509 at all ?

The advantage of BLS over a more common signature scheme, such as ECDSA, is that it produces shorter signatures. Shorter, not necessarily short. If you want n-bit security (traditionally, n = 128; current technological limit to the breakable is somewhere between 75 and 85), a BLS signature will need to have length at least 2n bits, while ECDSA requires 4n bits. Note that even with BLS, we are still talking about at least 200 bits or so, which is a lot for human-powered input. For instance, a Windows product key uses 25 characters taken in a 24-sign alphabet, which is sufficient to encode up to 114 bits, no more (because 2425 is approximately equal to 2114). If you want human users to type signature values, then even with BLS you are considering an effort similar to entering two product keys (four product keys with ECDSA). In most contexts this is probably too much to ask (indeed, if you could ask for more, then Microsoft would also do it and use longer product keys, precisely so that they could use cryptographic signatures like BLS...).
If you still want to delve into BLS, then start with the PBC library. It is written in C, but the conversion C-to-Java is the least of your worries -- understanding the usage context and the maths is a lot harder. I am not aware of any openly available Java implementation of pairings, but it is absolutely doable (I can guarantee that, because at one point I wrote a pure Java implementation of pairings). Depending on your existing knowledge in maths, crypto and development, obtaining a functional, reasonably secure implementation could take you several years of full-time work. Personally, I have already done that once, so I know all the maths and crypto, and I have done a lot of crypto implementation in Java, and it would still take me at least two or three weeks of full-time work to produce something that could be described as "decent".
Edit: actually a simple Google search with terms "BLS signature java" uncovers jPBC, which appears to be a Java port of PBC. All my points about the need to understand the maths, and the interoperability issues, still hold.

(*) It is possible to encode a BLS public key using the generic format for elliptic curve public keys, but that format does not include any field to notify decoders that the curve is appropriate for any specific kind of pairing. Even if the software receiving that key can recompute the embedding degree, there is no way to indicate the pairing type to use (Weil, Tate, any distortion map...).
Comment: Thank you very much for your effort, Thomas, it is really useful and interesting. How can we estimate the trade-off between usability and security in case of shortening the key? (I don't really understand why current technological limit is defined by you as nearly constant value — isn't it just a matter of time and computational resources when any protection mechanism will be broken?) Please tell me if it's already point I should start asking new question rather then discussing at comments.
Comment: Computational resources that can be mustered by any attacker are limited by his budget, to buy hardware and to buy electricity to power the said hardware. There is only so much you can have with a billion dollars. Technological advances tend to increase the amount of computing you can do with a given budget; look up "Moore's law". Right now, a rich organization (say, Apple or Google) may have the cash necessary to envision a 2^80 or so breaking effort, though of course they will do it only if the result is worth it.


Reduce size of image with a fixed div

Question: I am allowing users to edit their profile icon,so that the users can adjust their icon to what part of the image to display.
I have a fixed
 with width 50px and height 50px; .This size will be used when users are editing icon.The image will be larger and users can drag and set what to show.In coding part i had taken width,height,top,left.Top and left is used to determine what to show.Hope you understand that.
My problem arises when the edited icon is shown in the top bar. I had set the width of the div as 30px X 30px. When converting 50px size to 30px i had subtracted 20px from the obtained width so that it fits inside the 30px div as expected by the user.The actual part where what part of the image is to be displayed causes problems, the top and left obtained is for 50px div using the top and left for 30px div the expected part is not displayed as you can guess that.
I want to show the part that is selected by the user.Check this jsfiddle: http://jsfiddle.net/4mDQf/
How can i do that?
Thanks!
Comment: Not sure what you're getting at. You want to allow users to slice out a specific chunk of an image for use as their icon, rather than just resizing the whole image down to your 30x30 limit?
Answer: I had figured out a solution:
Cut the part to be displayed in 50px and shrink the cut image to 30px using php.

Reduce size of image with a fixed div


Can I convert freewheel hub to use cassette?

Question: I'm converting a 1989 Trek 830/Antelope MTB to a commuter and it has a freewheel. Can I convert it to a cassette with the same hub?
Comment: I'm sorry but I don't see a question here. Stackexchange is not a forum where a generalised discussion starter like this is appropriate. Could you possibly edit this down to a specific, answerable question?
Comment: Why? You can still get decent freewheels pretty cheaply (10-20 USD).
Comment: Depends what you mean by same hub.  Also I agree with Batman in that 7 and even 8 speed freewheels are inexpensive.  What is your goal in moving to a cassette?  How many cogs does your current freewheel on your MTB have?
Answer: No, it is not possible. You need to replace the entire hub, and the easiest way to do that is to replace the entire wheel.
Comment: Also, with a 1989 era bike that probably means spreading the frame so it can accept a modern hub.
Comment: Modern MTB hubs which don't use thru-axles are likely to be 135mm OLD, while "retro" MTBs may be 130mm at the rear... Such a frame is unlikely to be using disc brakes, so there's no reason not to use a 130mm "road" hub.


Does any MariaDB engine have the option to declaratively or configuratively abstract highly-redundant data?

Question: I have an application which is architected in a "NoSQL" style around one fully denormalized "main table" which currently just holds a primary key and one JSON-valued column. For reasons which are outside the scope of this question, I want to retain this architecture: I do NOT want to go full relational and create a proper normalized data model with entities, foreign keys, etc. I would be willing to parse out the JSON fields into their own columns, if that helps with the question below.
The data has a very high level of redundancy, e.g. some long-text column values such as names, addresses, and descriptions may be repeated 20 or 30+ times across different rows.
Is there a MariaDB engine which can declaratively or configuratively deal with this type of redundancy by internally de-duplicating the values across rows?
I imagine different ways this might be implemented in MariaDB would involve an extension to the BLOB or TEXT data types to leverage a content-based hash along with reference-counting or garbage collection.
What is meant by declaratively: it can be accomplished via a single "ALTER TABLE" statement. What is meant by configuratively: it can be accomplished by modifying one or more system variables.
I have read about ColumnStore, TokuDB, Mroonga, Parquet, and MyRocks but I'm not quite sure this is what they do, as the documentation is very sparse.
This question is specifically about a storage engine to help internally optimize the storage of redundant data. Please refrain from telling me to rearchitect, redesign, or refactor the application.
Answer: In any RDBMS, "normalization" is an explicit task that the programmer does.
Having stuff buried inside JSON strings makes that task more difficult.


Can I install FIFA 14 on Lumia 520 with Windows Phone 8.1?

Question: Can I install FIFA 14 on my phone, running Windows Phone version 8.1?
Comment: If you try to find it in the Store in your phone and you have free space to install (more than the download size),  yes, you could.
Answer: FIFA 14 requires a Windows Phone with 1GB of RAM to run, so unfortunately the Lumia 520 will not run this game.
If you search for FIFA 14 in the Store app, it won't show up as games or apps that require 1GB of RAM are hidden.
If you happen to open a direct link to the game, either on your phone or via the Windows Phone website, you should see a message saying...

Your phone doesn't meet the minimum requirements needed to run this
  app.
Comment: @agharehanabbas EA may update the game to work with 512MB devices, but we have no way of knowing if that will ever happen.
Comment: yup that was the same thing i got online on pc


How do I got back further than 12 months in the forecast tab?

Question: I use the forecast tab extensively in combination with split revenue between sales reps.  Forecast shows this quickly and easily however I look at previous years data for comparison and the forecast tab only allows me to go back 12 months.  How can expand the look back 18, 24+ months?
Answer: Salesforce Forecast tab doesn't go beyond 12 months.

You can prepare reports on Forecasting. Refer Create a Custom Report Type in Collaborative Forecasts

For this create new Report Type, selecting Forecasting Items or Forecasting Quotas and related child objects like Opportunity or OpportunityLineItems.
In the report you could specify wide range of forecasting tenure.


Can anyone explain the Ricci curvature?

Question: I am 13 years old and love physics. Can anyone explain simply what it is?
Comment: Possible duplicates: https://physics.stackexchange.com/q/2447/2451 , https://physics.stackexchange.com/q/92741/2451 and links therein.
Answer: Let's start with some mathematical basics. Some physical quantities are a single number; others are like a string of numbers, called a vector; still others expand this string to a rectangular array, called a matrix. A matrix is a $2$-dimensional arrangement of numbers; to say which of its entries you're talking about, you need two numbers to pick a row and column. The "shape" of spacetime is described by a matrix called the metric tensor, denoted $g_{ab}$. The value of $a$ specifies the row, and the value of $b$ specifies the column; and these indices can each have one of $4$ values, because spacetime has $4$ dimensions ($3$ of space, $1$ of time).
But there are other quantities with even more dimensions. They're harder to write down, because a sheet of paper only has a $2$-dimensional surface. However, if you wanted to specify a $4$-dimensional cousin of a matrix, say $X_{abcd}$, you just need to go through all choices of $abcd$ specifying the result.
Now to the physics. To understand the Ricci curvature, we must start with the Riemann tensor, denoted $R_{abcd}$. This collection of numbers measures the curvature of spacetime. On a flat surface, moving short distances in one direction and then another gets you to basically the same place if you change the order of the movements, but in curved spacetimes this doesn't work, and the Riemann tensor measures how much of a difference the order makes. It doesn't take $4^4=256$ independent numbers to specify this because of some constraints, such as $R_{abcd}=-R_{bacd}$; there are actually just $20$ degrees of freedom.
So what's the Ricci curvature? It could actually refer to two things, both expressed in terms of the Riemann tensor. The metric tensor I mentioned before is an invertible matrix (you can "multiply" matrices, so the inverse is a bit like a reciprocal), and its inverse is written $g^{ab}$. The Ricci tensor is defined as $R_{ac}=g^{bd}R_{abcd}$, where the rule is you sum over all possible values of any repeated indices (this is a bit like taking a scalar product of two vectors, of you've learned about that). Similarly, the Ricci scalar is $R=R_{ac}g^{ac}$.
So what are these two things named after Ricci, in short? They're quantified descriptions of how curved spacetime is. However, they don't provide a complete picture of curvature; you need the entire Riemann tensor for that. Some shapes spacetime can conceivably have result in $R=0$ even if the Riemann tensor contains some nonzero entries, which means the spacetime has to be curved.
Answer: Ricci curvature is the explanation of curvature Einstein opted for in his field equations. There are two types of Ricci curvature: the Ricci tensor and the Ricci scalar. I will explain the tensor as that features more heavily in the Field equations.
The Ricci tensor is a rank two tensor, found by contracting the Riemann tensor. It explains the curvature in terms of how the volume of a geodesic ball changes as it moves through the space. Imagine a sphere in some space, if you assign a vector to each point on this sphere then we can parallel transport this ball and all the vectors with it. We know that if space is flat then the vectors will remain unchanged- even after this translation, leaving the shape and volume of the sphere unchanged.
Alternatively, if the space is curved then the vectors will either diverge or converge after the parallel transport. These vectors, diverging or converging will change from the original spherical formation they were originally in. This change in shape will most likely come with a change in volume. Such a change in volume of the sphere can be measured and is representative of how curved the space is. In a very curved space; the vectors will diverge more and the volume will change a lot, and vice versa

Can anyone explain the Ricci curvature?


Does bioluminescence communcation occur on macroscopic level?

Question: Some bacteria are known to communicate using bioluminescence (quorum sensing). Do we observe the same phenomena in any macroscopic species?
Comment: don't know about bacterial light speech, but fireflies find their mates that way; or is your question specifically about quorum sensing?
Answer: Almost certainly. In the deep-sea, some species of laternfishes (Myctophidae) show sexual dimorphism in their light organs. Males have large light organs. The females are much smaller. Here is a brief summary, based on an interview with Dr. John Sparks at the American Museum of Natural History.
Sparks is discussing his recent publication with colleagues (Davis et al. 2014) that suggests that bioluminescent communication may actually facilitate speciation in some deep-sea fishes.
There are probably more instances of communication using bioluminscence in deep-sea organims but, to my knowledge, the Davis et al. paper provides the best evidence so far.

Davis, M.P. et al. 2014. Species-specific bioluminescence facilitates speciation in the deep sea. Marine Biology 161: 1139-1148. (open access)

On land, Stoltz et al. 2003 has demonstrated that positive selection has acted on bioluminescent color in Jamaican click beetles. The male beetles use the flashing to attract females for mating. Some males emit yellow light while males in a separated area have orange light.

Stoltz, U. et al. 2003. Darwinian natural selection for orange bioluminescent color in a Jamaican click beetle. Proceedings of the National Academy of Sciences USA 100: 14955-14959.
Answer: Some species of fireflies (Lampyridae, Coleoptera) synchronize their light patterns during the mating procedure. link


correlation b/w continuous and binary variables

Question: In a discussion, one claimed that because gender has only two categories, he can correlate it with a continuous variable.
Is it acceptable to use Pearson correlation between one continuous and another  binary variable?
Comment: Have a look at this post (and my answer there):  http://stats.stackexchange.com/questions/131065/non-transitivity-of-correlation-correlations-between-gender-and-brain-size-and/131069#131069
Comment: You can, but why not use a test that is actually appropriate, such as z- or t-tests for means?
Also, it's questionable if there are truly precisely two genders (or sexes).
Comment: Thanks for your reply. What made me confused was that he said as long as we have only two categories(male and female) we can use Pearson correlation coefficient but if there are more categories we cannot.What I understand is that Pearson correlation coefficient only used with two approximately normal continuous variables. Am I right?
Comment: See also [Proof of Point-Biserial Correlation being a special case of Pearson Correlation](http://stats.stackexchange.com/q/105542/17230) & [Can binary data be ordinal?](http://stats.stackexchange.com/q/169604/17230).
Answer: Sex is a nominal variable:  There is no origin, no ordering, etc.  However, most dichotomous nominal variables can be treated as dichotomous continuous variables.  And when you do that, the cases degenerate to the same result.
Consider a simple regression in your case of two sexes.  Code males as zero and females as one.
Because the regression is asked to fit two parameters and the "intercept" will be the male mean and the "slope" is going to be the difference between the female mean and the male mean (intercept).
The $F$-test for this regression will degenerate to the $t$-test for the two groups (literally, $F=t^2$).  The $F$-test would also test for slope=0 or correlation=0 because all these tests degenerate to the same test under these conditions.
By the way, the coding does not matter in this simple case either.  You could code males=-1 and females=+1 and the answers will be the same.
When you get more than two cases, though, where you place the third and additional points matters and it is not longer degenerative.
Does this help?


Sculpt hard edges mouth

Question: I've been trying to sculpt this mouth in sculpt mode but I can't get the surface to enter enough inside the head or make the more detailed sides... Is there any tip on how to 'maximize' the sculpt brushes? Or any other tip would be very helpful, thanks a lot!!
Comment: Seems like you don't have enough geometry for such details. To add more you can enable Dyntopo (on top row) to let dynamically generate vertices where needed or add Multires modifier. Sculpt as you need, use Pinch brush to sharpen edges. But with sculpt expect very dense mesh. For object like this would be probably better to model those vertices in edit mode (clean topo).
Answer: I'm not very much into sculpting, but you can try the Layers tool. Make sure you are in Subtraction Mode (the minus-button on the top) and set the falloff type to Constant.
But to make the edges so smooth like in your reference, you would need a hella lot of vertices, which can be performance-eating.
This is the closest result i achieved with sculpting lol:

You could try it with Bump Maps. I have to admit I haven't done this myself, but i've seen a colleague doing this. Basically you use an image with black an white values (black = low, white = high) as your source for the heights.
I think you would have to paint your mouth in grey tones and a sharp edge on a white background and plug in certain nodes in the shader editor.
I found a pretty short, but on-point-tutorial on this, which i can recommend (warning, it may be a bit fast): https://www.youtube.com/watch?v=_dU3DONwSzU

Sculpt hard edges mouth


DNA vs Family Tree

Question: I recently got a DNA match for my wife and it was suggested that this man is a 1st cousin once removed or 2nd cousin.  When I pursued that branch of the tree to confirm the match, it seems they are actually 3rd cousins.  With a 3.6% match and 252 cM, is there a way to know which one is more likely?  Or is this just one of those things where the estimate of relationship is nothing more than a guess?
Comment: [DNAPainter](https://dnapainter.com/tools/sharedcmv4/252) is your friend here.  It gives you a list of possible relationships and probabilities. Some of them, I suspect, you will be able to rule out immediately (great-great-uncle, for example)
Answer: You are correct it is just an estimate based on the mathematical range of the cM's that they are using to identify a cousin. For example on one website a third cousin is 0-217 cM but on another company chart a third cousin is 0-109 cM.

DNA vs Family Tree


Do I need to password protect [web] services that are only accessible internally?

Question: I have transmission-daemon setup with RPC enabled using a whitelist. The whitelist contains only 127.0.0.1 and my virtual private network range of IP addresses. I connect most of my devices through an openvpn server, and so I am wondering why I would need to enable standard auth (user/password) for services that are only accessible internally/by me. I know that this is only as secure as safe I keep my VPN/ssh keys. I am the only one (besides the hosting company) that has access to this server, so I can't really find a reason to have a username/password which gives me more things to remember and makes the process of using these services generally more cumbersome. Thoughts?
Answer: By having mo auth you are opening up more attack vectors. Couple of examples I can thin of:

Network is compromised and the attacker manages to get one of the IPs from VPN range
VPN is compromised and attacker gets access to the network that way
Another service on the server is compromised and attacker makes the requests from server (127.0.0.1)

All these attack vectors would give the attacker full access to the service you have described. Having auth on the service would fix that.
Comment: It's also a lot easier to build these things in at the start than later.
Comment: CSRF is a different issue. having AUTH would not help. You would need a csrf token to protect from that.
Comment: +1. It doesn't even need anything to be compromised though. A CSRF on the *intranet* can usually be exploited by a malicious page on the *internet*, so unless the *intranet* is air-gapped, you'll need to password protect your internal webpages.
Answer: Your network or VPN does not even have to be compromised. Any external website could over a client with has access to that server request a url. A common attack scenario is i.e. calling some services on "fritz.box" from a regular website, which might have some xss vulnerabilities. Usually fritz.box is not accessible from outside, but so many internal networks are using that hostname, so you can gain very easy access to an internal host, through the compromised website a client has visited.
Comment: Again, auth will not protect from that.


Channel Entry with Matrix clone or duplicate

Question: Does anybody have an idea of a plugin that can clone/duplicate channel entries that use the Matrix plugin? I have found MX Cloner (http://devot-ee.com/add-ons/mx-cloner) however this is not compatible with Matrix.
Answer: I beg to differ. We recently updated Matrix to version 2.5.6 (on EE 2.6.1), and MX Cloner 1.2.1 stopped working. They may update it, but until they do, Devot-ee''s information appears to be accurate.
Comment: Well, just tested it again (EE 2.7.3, MX Cloner 1.2.1, Matrix 2.5.10, CartThrob 2.5, Products channel with a matrix variations field of 13 columns and 7 rows, and about 45 fields in all) - works perfectly here.  Me and my staff have used it extensively over the prior 6 months without issue.  Doesn't mean there is no issue at all of course, just maybe that it is not a general one.
Answer: The devotee information is wrong in this case - I just tested mxcloner with a complex entry with a big matrix inside of it and it cloned it perfectly.
Answer: I work on a very large site that is heavily reliant on the Matrix extension: EE 2.7.2, MX Cloner 1.2.7, and Matrix 2.6.
Haven't had any issues with that particular combination.


Problem with flex air application

Question: Good evening stackoverflow.. I am having problems with my flash builder 4 project
it is an air application and has a php service
Most of the time my app run fine but sometimes I recieve http errors and don't know how or why it happens. What I do is restart my app and it would run smoothly. One thing I noticed is that the busyCursor keeps on turning. It's like it loading something I think it is the calls that I make. I don't understand why sometimes it fails sometimes it works...could you help me clear this thing out??how can I avoid such errors?
Answer: Install one of network monitors e.g. Charles and find out what fails.

Problem with flex air application


Sign of work in adiabatic expansion

Question: I know that in an adiabatic expansion, $W = -U.$ My question is, is the work positive or negative? I'm confused on the difference between work done "by" the system and work done "on" the system.
Comment: Possible duplicates: http://physics.stackexchange.com/q/37904/2451 and links therein.
Comment: You can use both convention. But you have to use 2 versions of the first law for 2 conventions. Then you can deduce whether work done on / by is positive from the fact whether the volume is increased or decreased.
Answer: The most common expression for the first law is
$$\Delta U=Q-W$$ where
$W$ is positive if work is done by the system (work out, energy out) and negative if done on the system (work in, energy in). An expansion is considered work done by the system.
But sometimes in chemical thermodynamics it is expressed as
$$\Delta U=Q+W$$ where
$W$ is negative if work is done by the system (work out, energy out) and positive  if done on the system (work in, energy in).
It doesn't matter as long as you are consistent. Think of like this. If energy is going out of the system, there will be a reduction (negative change) in internal energy, and vice versa. Both versions are consistent with this. And of course, $Q=0$ in both cases for an adiabatic process.
Hope this helps
Answer: Work done $by$ the system is positive. This is just a convention and interestingly the opposite convention about the sign of work is taken in chemistry.
Answer: Work is equal to the product of force and displacement.  So if the force that A exerts on B is in the same direction as the displacement of B, the work that A does on B is positive.  If the force that A exerts on B is opposite to the direction of B's displacement, then the work that A does on B is negative.
In the equation that you have written, W is the work that the system does on its surroundings.  It can be either positive or negative in sign, depending on whether the gas expands or is compressed, respectively.

Sign of work in adiabatic expansion


Using abbreviations in 15th Century English

Question: I am writing a story set in the 15th Century. I appreciate that most stories etc were written at the time in either Latin or French but, for obvious reasons, I have to write it in English. It is written in the 1st person and, to make it more personal and immediate, I am considering using abbreviations such as 'I've' and 'I'm'. Would such abbreviations have been used in 15th century English?
Comment: *"I am writing a story set in the 15th Century."* Do not attempt to use 15th century English (late Middle English) unless you are willing to study the subject for 3 or 4 years. You are certain to make many horrible mistakes, and not only in contractions, which are the least of your worries.
Comment: Shakespeare used *I'm*, *I've*, *you're*, *thou'rt*, *he's*, etc. (Although this was 16th century.) But use *'tis*, and not *it's*.
Comment: This might help you: Elizabethan English, also, of course, the Bard. https://www.wappingersschools.org/cms/lib/NY01001463/Centricity/Domain/1504/Elizabethan_language.pdf
Comment: Thank you Peter.  very helpful.
Answer: Subject-verb Contractions
Middle English at the time did have a contraction for "I have" (and I plus other verbs), but it's not the same as "I've": ichabbe, ichave. These forms reflect the pronunciation of ich, which was the form of I inherited from Old English and was undergoing a shift in pronunciation to its modern pronunciation and spelling.
'Tis was apparently in use in the 15th century. 'Twascame into use in the mid 1500s, a little later.
I don't see any evidence of similar contractions being used with other pronouns during the 15th century.
Negative Contractions
The only modern negative contraction that I can think of that was in use in the 15th century is cannot. From a c1450 Treatise on Fishing:

Ye cannot brynge a hoke to a fyche mouthe but yf þer be mete ther-on to hys plesur. (You cannot bring a hook to a fish's mouth unless there is meat on it to its satisfaction.)

There are other words like it (such as wilnot) but none of them survived to modern English. Middle English also still had the negative contractions from Old English (ne + is = nis), though these are even harder for a modern audience to decipher.
As for when people started using modern negative contractions: "The contracted forms [of not] seem to have come into speech ... about the year 1600" — Negation in English and Other Languages in The Contractions of not: A Historical Note (which explains in more detail about how n't came to be).
Other contractions
There are some other contractions that existed at this point, but they're not terribly useful in the modern age.
Comment: THANKS YOU LAUREL.  VERY HELPFUL.


Can I create a PNG from InDesign?

Question: I usually have to export my InDesign file into an eps, then convert it to PNG in illustrator.  Does anyone know an easier way?
Answer: Sadly, there isn't a straighter native way. There has been some threads on the topic on Adobe forums and even an Adobe employee recommends exporting the image in PDF and opening it in Photoshop — though it is kind of same as exporting it to a EPS and opening it in Illustrator.
One other thread comes to the same conclusion, but someone does indeed notice that it may be achievable with scripting.
Workaround for Windows: Install PDFCreator, which adds a virtual printer to your system. While PDFCreator is designed to create PDF-prints (for desktop & home use), it can print as PNG:

Create more than just PDFs: PNG, JPG, TIFF, BMP, PCX, PS, EPS

Then you could just print the pages you want as PNGs. (There might be some problems regarding transparency, though.)
Sadly, I'm yet to know any alternatives for OS X — but I'd be happy to hear one, since it's currently my primary platform.
Comment: It *is* achievable with scripting. INDD to EPS to PSD to PNG is one of the processes I have automated for a product my company produces. We do it all the time.
Comment: +1 for the PDFCreator. Without any additional fuzz you can do exactly what's expected.
Answer: Just a little update. In Adobe Indesign 2020 now it is possible to do both things, export your pages to JPEG or PNG format, and select a specific page or spread.
Just go to File/Export. In the dialog box pic your preferred format. Then another window opens. Here you can choose to export all your pages or select a range. Now you can choose your file quality and PPI.
Answer: I don't know of an easier path than that—though I use Photoshop to rasterize EPS files—but it is a fairly simple thing to script (at least from a scripting standpoint).
Comment: philip - can you share that script? to convert a indd to png w/ transparency?
Answer: If you want to make a PNG for each page, simply choose File > Export and select PNG as the format.
If you want export individual items, this can be done pretty simply with a script. in5, our InDesign to HTML5 exporter, generates PNGs as part of its output. You could use our product and collect the images, or you could try the built-in epub export and see if you can collect the images produced (just renamed the package to .zip and unzip to get access to the files), or write your own script/hire it out.
Edit: According InDesign Secrets,Layout Zone will also export a PNG of any item.

Can I create a PNG from InDesign?


Where do you put client-side source files when using grunt and maven?

Question: Typically on a Java project using Maven, you place client-side source files in src/main/webapp. This directory includes your html, css, scripts, images, etc.
However, many grunt projects tend to place these files on the root. It's as if Grunt was designed with the idea that your project is the client-side application, not part of a large server-side project, such as using Java with Spring.
Given a Java project using Maven, where would be the best place to put your web-related source files?
Do you place them in src/main/webapp?
Do you make another directory altogether, such as src/web, and then on a build, copy everything to src/main/webapp?
My goal is to make the client-side build tool as transparent as possible. I guess the ideal case is to simply work from src/main/webapp as I have been doing all along - this is pretty unobtrusive to the way my project is currently setup.
However, if I work from src/main/webapp, I know that I will need to distinguish between src and build directories somehow anyway. I'm sure my html files can stay where they are, but there's definitely going to be a conflict of interest here with javascript and css files, and maybe images too.
Does it make sense to literally have a 100% separate source folder from src/main/webapp? Is there a way to do continuous building/copying/syncing of the application as you modify files, from src/web to src/main/webapp? Will this be inconvenient and cause frustrations and problems? Is it slow?
I would like any advice on the subject. Thank you.
Comment: possible duplicate of [Where to put grunt/bower/etc. files for Maven-based spring project?](http://stackoverflow.com/questions/21445148/where-to-put-grunt-bower-etc-files-for-maven-based-spring-project)
Comment: Can you either delete your duplicate question or tell u s how this one is different?
Comment: @Anzeo Link you provided is unreachable
Answer: Option 1: Put UI resources in src/main/webapp:
This is a quick-n-dirty solution popular on Github. It helps to keep example projects small and concise. In this case, usually people put the package.json, bower.json, Gruntfile.js and .bowerrc in the maven project's root directory, where the .bowerrc says to install components into src/main/webapp/bower_components.
If you have a task that minifies/transforms resources, the transformed resources can go to a new directory like src/main/webapp/dist. Then use something like grunt-usemin to make your app use the resources in the dist directory.
If your application will use a security framework (like, say, Spring Security), you might want all your resources in src/main/webapp so that the security framework can regulate access to those resources. However you can still achieve this using Option 2 by having a grunt task that copies the necessary resources into src/main/webapp.
Pros

Common approach on GitHub. Keeps everything in one project.

Cons

The version of files getting served by your server is a copy of those in src/main/webapp, so changing a file in src/main/webapp isn't immediately reflected in your deployed app. To get hot reloading, you need to use something like grunt-contrib-* stuff.
Frontend and backend code is all mixed together. Harder for two different teams to work on the code base.

Option 2: Put UI resources in a separate project:
You can achieve better project organization by keeping the UI and backend in completely separate projects. In this case the UI and the maven project would likely be sibling directories.
Then when deploying to a server, you either:

deploy both projects separately (call them myproject-ui and myproject-services). The javascript in myproject-ui makes RESTful service calls to myproject-services/**.
Use a grunt task to copy necessary resources to src/main/webapp, then deploy your (one) project.

Pros

The backend and the frontend are separated as much as possible
The frontend maintains the workflow and directory structure found in most client-side example apps, as you mentioned
"Deploying" the UI is a simple matter of creating a symlink from your server's deployment directory to you UI source code. Changing any UI code is automatically reflected in the deployed app.
You can have several different UIs deployed simultaneously (maybe you have myproject-admin-ui and myproject-user-ui). You could hit either one simply by visiting
http://localhost:8080/myproject-admin-ui
http://localhost:8080/myproject-user-ui


Disabling other domain users in openfire?

Question: Is it possible to disable other domain users to add my domain users as friend in openfire? I mean I have a domain, say abc.org and I want only users with abc.org domain can add each other as friends. Someone who has a domain like jabber.org couldn't add a user who has a domain like abc.org as a user.
Answer: You can use PrivacyList extension of XMPP. Though, i have no experience using this, however, it can suffice your objective to block certain domains.


Can a well pump be moved from inside to outside?

Question: Due to the noise and unsightliness of the pump, wife is wondering if we can move it outside...
Comment: Does it freeze where you live? Where is the well with respect to your house? You might do better to change to a submersible pump, which puts the "noise and unsightliness" out of hearing and sight down the well-hole. But that depends on the size and depth of the well... Details are needed to provide a reasonable answer.
Comment: Hello, and welcome to Home Improvement. We'll need more info before we could help you. And, you should probably [take our tour](//diy.stackexchange.com/tour) so you'll know how best to participate here.
Comment: How many pipes connect your well to your pump?
Answer: The primary factor in the relocation of your well pump will be the climate you live in.  If you are in southern Florida and it never freezes, then things may likely work out well for you (no pun intended).
If you are in an area that gets freezing temperatures from time to time, things may not work and you could actually do damage to the pump, tank and other components if they were to freeze.
Sometimes there is a little "pump house" which is insulated, and also heated, which helps deal with climate issues, but heating a small pump house can be an additional cost, which one may find unacceptable.
One lower cost thing you could consider, is making an enclosure to cover the indoor components.  Should you decide to do so, you may wish to make that enclosure readily knock down, so that you can gain access to the components without a structure around them limiting accessibility.  You will also want to consider a double wall, or staggered stud construction to isolate noise from the pump.  You will still have some noise.  Better rubber isolation feet may help.
If your well setup is getting near the end of it's life, you might plan transitioning to a submersible pump.
Answer: A surface mounted pump can always be moved, yes they are noisy, and inefficient.  This last year I changed my jet pump out to a submersible. Happy with the change all lower power bill.
If you have a jet there will be 2 lines to the well, basically you shorten these and extend the line to the pressure tank and extend the wiring. So yes it can be done.


Found bags of LEGO bricks at a thrift store. What sets they belong to?

Question: I am wondering if anyone can try and help me identify these bags. I picked them up a thrift store and all my googling has come up empty handed
This is the first bag

Second one

Third one

Then there was this small one with no identifications on it

And finally these loose pieces
Answer: Those all look like parts from set 31109 Pirate Ship released in 2020 :

Note this assumes the colors aren't accurately represented in your pictures. Eg. the 10 loose pieces appear to be reddish brown from your picture, but would be medium nougat in the set. Additionally, dark azure parts look like regular blue, yellow like pearl gold, pearl gold like brown, dark bluish gray like black, etc. in your pictures. Ie. all colors appear darker in your pictures than they'd be in real life.


Clicking the browser Back button to return to an ajax page and have it look the same?

Question: I've tried doing some research on the various jquery history plugins, but I can't find any examples for my situation, so I'm starting to think maybe what I'm trying to do is not possible.
We have a very complicated search page that updates with ajax.  Users search using a ton of options, and they get back a list of results which they can sort, page etc.  Then if they click on one of the results, it navigates them to another page to view the details.  However, if they click Back they do not return back to how the page appeared after all the ajax and javascript updates.  They see the search page with none of their results.
I was hoping that I could pull of something with adding a hash before they navigated away, or using one of the jquery history plugins to achieve something similar, so that when they clicked Back, it wouldn't RELOAD the search page, but would just show them their cached version (how it last looked when they clicked on one of the results).
From what I've seen, it looks like most of the examples I've found for ajax and back buttons use a hash value that tells the page how to arrange itself, even allowing for bookmarking the page that includes the hash.  I think for me that would mean that I'd basically have to serialize everything in the search page into a hash value, which doesn't seem practical unless I am totally misunderstanding how it works.
Does anyone out there know if this possible?
Comment: Perhaps use a history plugin?
Comment: Have you considered using cookies? http://stackoverflow.com/a/2257895/577264
Answer: There are at least 2 ways to do what you want:

"Classic" - store all user search options in cookie or in session, like "last search". So, when user navigates to search page during session, you can read cookie / session and show last search results with that options.
"Modern" way - use HTML5 history API - on each search form a search options object and push it in via history.pushState - when user navigate to other page and then presses "back", browser will use this state to perform a search.
Comment: Ok so it looks like there is now way for the page to just automatically display how it appeared when the user left it is that right?  Either way I'll have to user JS to save the entire state of the page into some container and then reconstruct the page when the user returns?
Comment: Yes, browser itself don't "remember" ajax requests in history, unlike normal URLs. You can only emulate it for user in a several ways.
Answer: If it's that complex, better you develop your own solution without any plugin. Just use location.hash to get and set hash value and store all form input elements and their values after hash like a querystring input1=a&input2=b
On every form submit update hash querystring
If user navigates back in history read hash value parse it and update your form fields and submit to get search results automatically.
Answer: you can check out SammyJS this is the plugin I used for ajax history. Hope it helps


Do I need a vent on this emergency drain?

Question: Code allows the use of a wet vent for the bathroom group which in my case is a sink, toilet, and shower drain. About 10-15 feet down stream of this group I have a washing machine drain with its own vent. I also need a emergency drain in my mechanical room. Does this need a separate vent?
Comment: what's an emergency drain?
Comment: floor drain. I thought that is what they are called in a mechanical room.
Answer: If it's really an "emergency" drain - one that you will never use in normal circumstances - then it shouldn't be connected to the rest of your plumbing at all.  It should just have a straight pipe leading into a basement sump pump, outside the house, or even into a crawl space (just put some screen over the open end to keep critters out).  The reason for this is that if you connect it to your normal plumbing, you will need a trap.  The trap stays partially filled with water to keep the smell of the sewer from entering your house. Over time, the water in the trap will evaporate, letting the sewer smell enter your room.  In a drain that gets regular use, this is not a problem, since you refill the trap every time you use the drain.  I'm guessing your "emergency" floor drain is only there to get rid of water if the washing machine malfunctions and overflows.  In that very rare scenario it's not a big deal to just let the water run into your crawlspace or yard, although directing it to a sump pump (and from the sump pump into your yard) is probably the best option since it keeps the open end of the pipe inside your basement if you have one.
Comment: There are solutions to the dry trap issue - a trap primer hooked up to a commonly used faucet will resolve the issue of lack of water in the trap. There are also trap primers that drip a small amount of water into the trap when there is flow through a valve so it doesn't even have to be connected to a faucet.
Comment: @Steven true, but if sewer pipe is blocked, an "emergency drain" not connected to that same sewer pipe is a good idea.
Comment: I think the OP just meant a floor drain in your utility room....
Comment: I had not thought about the dry trap issue in this room. Thanks for bringing that up. The drain in that room is for the pressure relief valve on the hot water heater. I will probably have that drain go to the outside under the deck. Still need a vent for it I believe then,
Comment: @pdfj If all you want to do is get the pressure relief plumbed outside, then you don't need a vent. Just plumb the pressure relief valve with PVC to the outside. No traps or vents needed since there are no sewer gasses you need to guard against.
Comment: Say I was to vent this drain. How would I do it? There is a wall that runs perpendicular to the drain arm about at the midway mark. Could i put a tee here and go up and connect to the vent above the washing machine?
Answer: "The code" allows wet vents but not through horizontal piping. And it can be any nearby fixtures on the same floor of a certain size, the fixture group requirement was removed. Of course, this depends on which code we are talking about, I'm mainly familiar with the IPC formerly UPC. Horizontal wet vents could still be allowed by other codes.
Your bathroom was probably constructed when that practice was acceptable. Doesn't mean you can do it now. In any case, wet venting is allowed for low flow fixtures draining into the sizable vent of high flow fixtures. You proposal for wet venting the washer through the floor drain's vent has the concept reversed, so it fails on principle. There would be a very good chance the washer flow would suction out the floor drain trap. It's hard enough to maintain a proper floor drain trap seal as it is.
The floor drain trap will need it's own vent, though once you are above floor level with the vent, you may make horizontal runs and tie into other vent pipes provided the sizing is appropriate. Some codes allow a mechanical venting device, which obviates the need to run the vent outside somehow.
Comment: Horizontal wet vents are permitted. P3108.1  Horizontal  wet  vent  permitted.  Any  combination
of fixtures  within  two  bathroom  groups  located  on the same floor level shall be permitted to
be vented by a horizontal wet
vent.
Comment: Thx, I will update my leaky grey file.
Comment: Note this was for the IRC code so you're grey file might not be so leaky.


ViewData in Master page for both MVC and WebForms

Question: In my site I have the same MasterPage for both MVC Views and WebForm Pages.
I want to use ViewData inside the MasterPage code behind.
I'm getting an exception:
A ViewMasterPage can be used only with content pages that derive from ViewPage or ViewPage.
public partial class MasterPage : System.Web.Mvc.ViewMasterPage

{
protected void Page_Load(object sender, EventArgs e)
{
    ViewData["X"] = "data";

This Code worked in a WebSite project - but I just converted to Web Application and I can't get it work run.
The Content Page inherits System.Web.Mvc.ViewPage
The ViewData need to be the same object in the pages and masterPages code behind.

Thanks
Rafael.
Answer: It may not be ideal for your purpose but one property bag that does exist and is easily accessible when running through MVC or WebForms views or code behind is the HttpContext.Items dictionary.