What xml schema context is generated the method signature like "JAXBElemet createXyz(Xyz xyz)" of ObjectFactory by xjc?

Question: I noticed the the simpleType or complexType is defined and the types are used in the declarations of multiple element in a schema file, the simpleType or complexType is generated a method signature as "JAXBElemet createXyz(Xyz xyz)". But I'm not sure if it is root reason.
Answer: In order to marshal an object to XML, JAXB needs to know the name of the XML element to be used. It gets this either from (a) the @XmlRootElement annotation on the class, or (b) by wrapping the object in a JAXBElement, which contains the element name.
If XJC generates a class without @XmlRootElement, then the factory methods for that class in ObjectFactory will instead use JAXBElement wrappers, to provide the required marshalling information.
You may then ask why XJC decides to generate @XmlRootElement for some classes but not others, but that's been asked on SO before, so go and have a look around for that one.


If the Earth didn't rotate, how would a Foucault pendulum work?

Question: How does the Foucault pendulum work exactly, and would it work at all, if the Earth didn't rotate?
Comment: 'Didn't rotate' relative to what frame of reference? Tidally locked with the sun is one possibility, as is the possibility that it does not rotate w.r.t the milky way centre, or maybe you mean a particular galactic cluster? Even the distant stars and galaxies are moving, so there seems to be no "universal stationary frame of reference".
Comment: @Jus12 The answer is given to you by the pendulum itself. If it doesn't precess than it's surroundings are an inertial frame (i.e. one which is not rotating).
Comment: Typically the response to this question given by flat-Earthers nowadays is that every Foucault pendulum is fake, and the precession is accomplished through hidden motors.
Answer: Well, for the basics of the Foucault pendulum, this wikipedia page does an adequate job describing how it works (Specifically read up on the Precession as a form of parallel transport section).
This page also has a nice explanation of how they work:

A Foucault pendulum is just like any other pendulum, nothing more than a weight attached to a wire; but to work well it needs to have a very long wire, with a really heavy weight. They're often attached to the ceilings inside very tall buildings, such as museums and cathedrals, so that they can hang a great distance and swing impressively slowly. These sorts of locations also tend to have fairly constant temperatures, which avoids expansion and contraction of the pendulum which would cause complicated variations in its period.
What makes a Foucault pendulum different from a normal pendulum is that it is attached at the top to a universal joint which allows the pendulum to rotate freely around its fixing point as it swings. Once you set one in motion, its direction of swing will rotate at a rate of about 0.2 degrees every minute. But in fact, it isn't really the pendulum that's rotating: the pendulum is swinging back and forth in exactly the same direction. It's the Earth which is rotating underneath the pendulum, which makes it appear that the pendulum is in fact changing direction.

Now, since I can't even conceive of a way to make a planet (or any other large enough body to build any type of pendulum on) that would not rotate, this is a purely theoretical exercise.  Bottom line:
The pendulum would swing back and forth, and never deviate from its original arc (assuming no wind or other disturbances) if it were set up on a non-rotating body.
Comment: TL;DR it wouldn't.
Comment: If a Foucault pendulum was set up on the Moon, the precession would be based upon the Moon's rotation around the Earth, yes?
Answer: I keep thinking the pivot would rotate with the earth and therefore the Foucualt Pendulum would not work. But upon further thought the pendulum must track in same line. The pendulum stays constant because gravity keeps it lined up with the center of the earth while the earth's crust rotates the center does little and holds the pendulum on plane while the earth rotates under it. So if the earth did not rotate then the Foucault Pendulum would track the same line since the earth would not be moving under it. What else but gravity could keep the Pendulum course constant?
Comment: And you're saying?...


German marriage query for Anna Waltraude ENSFELDER born Hamelin

Question: From family Stammbuch Anna Waltraude ENSFELDER was born in Hamelin/Hameln, Germany in 1912. She had a daughter Ursula. Can anyone tell me who she married?
Answer: Get in touch with Stadtarchiv Hameln (https://www.hameln.de/de/leben-in-hameln/bildung/stadtarchiv/) and the local civil registration office (Standesamt Hameln, https://www.hameln.de/de/buergerservice-verwaltung/buergeranliegen/standesamt/) and ask where the birth records from 1912 are kept. Get a copy and if she was married a side note should indicate time and place of marriage. Try to get the marriage record from there. If the suspected husband was the father of the daughter mentioned above, he should also be listed in the daughter's birth certificate.
Always state your relationship and when the person of interest died. This might be helpful if privacy restrictions apply.
Comment: Belated thanks for your help. I'll certainly check this out.


Is it safe to eat butter after it has crossed its expiration date? Does butter ever spoil in fridge?

Question: I just came back from a long trip and I was cleaning out my fridge, and I noticed that there is an expiration date on the butter. It expired about two months from when I bought it. The butter doesn't look any different than normal butter.
How strictly should I follow the date on the box? Is there a way to test to see if the butter has actually gone bad?
Answer: Butter can go bad.  The oils will go rancid if exposed to too much light and heat for too long.  This accelerates the process of oxidation, which happens even if you keep the butter in the fridge.  Even in the fridge your butter will eventually go bad.
Personally I follow the dates on all packages.  I do so with an awareness that they usually tend to be conservative, which keeps me comfortable.  Rancid butter in a taste test won't kill you, though.  It'll just taste bad.  So you should be able to taste this butter to see if it is bad.
While I recommend following the dates on packaging, here are signs that your butter has actually gone bad:

discoloration
melting (which will happen outside of the fridge, you probably wouldn't see it)
sour smell
sour and unusual taste
Comment: +1, as I've had butter go bad in the fridge myself. Took a LONG time though (no clue how long). Generally I toss butter when discoloration get's too bad. Sour smell or taste is an immediate toss.
Comment: I've kept it in the fridge for up to a year with no problems (it goes on sale between Thanksgiving and Christmas). Some recommend freezing for anything longer than six months: http://www.eatwisconsincheese.com/wisconsin/other_dairy/butter/butter_basics/butter_storage.aspx Of course, when cold-storing large quantities of butter, you should take fire-safety into account too: http://madisoneast.channel3000.com/news/news/madison-butter-fire-remembered-20-years-later/51957
Comment: Also consider salted vs unsalted.  Unsalted butter will maybe last a week or so during the summer before it goes bad on the counter (or in the winter, if you keep your house too warm).  Salt acts as a preservative and can give you more time, maybe another week or so.  The preservative properties of salt can also work in the fridge.  FWIW, I still have a pound of butter in my fridge from last xmas, and it is discolored but not quite bad.  I will probablly toss it soon and buy a pound to hold me over until baking season...
Comment: Since I buy my butter when it goes on sale, and keep it in the freezer, I don't think I ever even look at expiration dates.  But I only have one stick salted, one stick unsalted, ever in the fridge at a time.

Also, if you keep your butter not in a sealed container in the fridge, even if it doesn't go "bad," it's going to pickup odors from all the other foods, over time, and will taste off, even if it's not "bad" for you.
Answer: Yes, butter can go bad. Rancid, for instance.
This question has been treated before in this possible duplicate - does that help?
Comment: @Tobiasodenbrouw - seems like a somewhat different question (with related answers), since one was about leaving butter out and this butter was in the fridge.
Comment: Yeah, it's a bit different. Still, the link doesn't hurt.
Comment: @Tobiasodenbrouw - definitely, just wasn't sure how to take the phrase "possible duplicate"


If PPP Exchange rate is 0.291, what does that mean?

Question: I've normalised deflators for countries A and B. If the Price level of Country A/ Price level of country B = .291, does that mean that on average for every dollar a person in Country B spends, for the SAME thing in country A it only costs about .291?
Answer: S =  P1 / P2  ; P1=Price at country A's currency for good X,
P2=Price at country B for the same good X and S is equal to the exchange rate of currency #1 and currency #2.
This formula measures the difference between the two countries' rates of inflation and the cost of commodities will drive changes in the exchange rate between the two countries.
this relates the change in two countries' inflation rates to the change in their exchange rate.
for every 1.00 dollar spent on the good X in country B, it takes  .29 cents to obtain the same good X in in country A buying it with country A's currency.
So if S doesn't match the exchange rate between the two countries for good X then one of the country's currency's is devalued.
As countries with higher levels of inflation are likely to end up with their currencies devalued
https://www.investopedia.com/updates/purchasing-power-parity-ppp/


The Inquisition

Question: What was the reason of the Inquisition, who started it, and did it do what it was supposed to do?
Comment: Is this on-topic and not easily google-able?
Answer: Here is the Wikipedia article on the topic.
Answer: If you are referring to the Spanish Inquisition this was done by King Ferdinand and Queen Isabella who were convinced by a friar to initiate it. It was obstensibly done to fight heresy but assumed they were fighting for more political authority versus the church's authority.

The Inquisition


Is it permissible to use Qur'anic quotes as decorations?

Question: Can I decorate my home or working place with Islamic elements? For example, using suras or words from the Qur'an, or kahbatullah pictures, or various du'as as both decoration and as a reminder so that we don't forget?
Comment: Whats the intention behind it, is it for decoration or as a reminder?
Answer: Peace be upon you,
If your intention is to decorate your home by this, then it is sinful. But if your intention is to receive Allah's blessings, then it is fine.
This is what I have heard from a scholar. And Allah knows best.
Comment: Source would be nice, but i do believe in that same opinion since one of the many things we are judged upon is our intentions.
Comment: I'm sure there are people who hold a different view. As @Musk suggested, please cite your evidences. Which scholar did you hear this from?


Moving money into Fifth Third checking account through Access 360 card

Question: My account was one of those compromised a bit back, and as a result Fifth Third cancelled my card and gave me a prepaid Access 360 card. Due to some mail complications I never received my new card, and my account is currently over drafted due to sloppy budgeting from yours truly. My roommate is willing to give me some cash to bail me out, but I'm curious if there is any way to get that cash into my checking account to get it back to zero.
Comment: Do you have a savings account?
Comment: Yep, but the balance isn't enough to zero the acct. Edited to avoid embarrassment.
Answer: Without access to the ATM/debit card and with almost nothing in savings, you will probably have to visit a branch to make a cash deposit.
If it is too far to drive you might be able to turn the cash into a money order and mail it to the bank, but I would check with the bank to see if that would work. Of course mail will take a day or two.
Comment: Thank you for the answer! Not to be annoying, but do you know if Fifth Third charges daily for overdrafts? Their copy is vague at best.
Comment: No idea. I don't have an account with them.


Why did ramjet AA missiles fall out of favor over pure rockets?

Question: In the 50's and 60's, when anti aircraft missile technology was blooming, many designs used ramjet engines brought up to operating speed by rockets. This seems like a good idea, since ramjets have significantly higher specific impulse than rockets, increasing their range. Over decades however, it seems that the concept has been discarded in favor of pure rockets, with exception of anti shipping missiles. What could be the considerations that made engineers favor pure rockets?
Comment: I don't think it is fair to say the concept has been discarded. Several projects to modify fielded missiles by adding ramjet sustainers have come and gone much more recently than the 60s. https://pdfs.semanticscholar.org/9330/17c8df43bfe6978ac0707595e53cb0c94829.pdf
Answer: I have worked on the edge of this technology. the simple answer is the performance of the scram jet doesn't make uo for  the added weight of the system.  The most recent work NASA has performed was the HYPER-X program, try this link.
https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-040-DFRC.html


Task Created When Email Alert Triggered By WFR

Question: I have a time-based WFR on the Account object that sends out an Email alert 2 days after a date that is stamped by Case records.  The email alert template is made up of a visualforce page that groups cases of similar characteristics.  This works fantastic, but the issue is I don't know that an email was sent. Does anyone know how I can create a Task once the email alert is sent?  The tricky part is that I need to pull in the cases that were included in the email alert, plus the contacts that are listed as fields on the Account record.
Comment: You want the Task to memorialize the cases+contacts used within the body of the time-based workflow's email alert?  This is a hard problem unless you persist those IDs in some SObject field associate or related to the target workflow object
Answer: You could do your custom task creation in a flow. If you do it that way, you can add a checkbox to your account record that also gets flipped when the email goes out. Then you can have a Process watch for that flag being flipped and then execute your Flow which will then do your task work or anything else you may want to do when the time based workflow fires. Just make sure you uncheck that checkbox as part of your Flow so the next time the time dependent action fires, it won't still be checked from the last time the action fired.


Multiple ffi definitions with ffi.include(...)

Question: I have some cffi definitions spread over a few project sub-directories -- each cffi file defines types and functions, each compiles into a _<package>.py file to be loaded. In the final application I ffi.include() the top level ones (which recursively ffi.include() the lower level ones) and generate an compile an  _<app>.py file to be loaded in the application. I use a single ffi instance for loading the *.so files. I cannot see however how this loads the spread _<package>.py files into the application. I get the following error (example):

two separate FFI definition files, root/get/ffi_getA.py and root/use/ffi_useA.py

which C functions are both part of the same library, say libA.so.
ffi_getA.py:
from cffi import FFI
ffi=FFI()
ffi.set_source("getA",None)
ffi.cdef('''
typedef ... A;       // type also used in another ffi definition.
const A* get_A();
''')

ffi_useA.py:
from cffi import FFI
ffi=FFI()
ffi.set_source("useA",None)
from root.get import ffi_getA
ffi.include(ffi_getA.ffi)         # makes available type A
ffi.cdef('''
const void* use_A(const A*);  // use type A
''')

In an application:
from root.get import getA  # compiled ffi
from root.use import useA  # compiled ffi

libAget = getA.ffi.dlopen("libA.so")
libAuse = useA.ffi.dlopen("libA.so")

a = libAget.getA()

libAuse.useA(a)  # !!! mixing !!!, a is indeed of type A ...
                 # ... but from a different ffi instance.

This mixing is not going to work, so the question is:
How to access/load cdef functions spread over various compiled ffi objects through a common/single ffi object?
Comment: @stustd instead of editing your question to share the solution you found, please post it as separate answer and accept it. You should explain it a bit more though.
Comment: Looks like cffi is not doing what you expect it to.  But you'll need to come up with a concrete example in order for us to help you (or fix cffi :-)
Answer: Solution
To build the cffi interface from a single ffi instance everything must start with a root python cdef builder script. From this script the ffi instance is imported and extended in the next builder script that depends on types defined in the previous builder script; and so on. Basically,
In foo.py:
ffi = cffi.FFI()
ffi.cdef("...")

In bar.py:
from foo import ffi
ffi.cdef("...")

In this way, there is only one FFI instance. (Likely, so called "diamond import dependencies" between cffi/cdef files must be avoided in order to avoid duplicate definitions).
Importing the ffi instances at the module level is crucial for the decorator functions to have access to the types defined. (Retrospectively this is trivial but at first I imported at the instance constructiong level and used a separate instance for the decorators - this worked until I needed custom defined types...).
Finally, in this procedure you won't need ffi.include(...) -- the "inclusion" is done through imports. Also, as the source is only generated in the final builder script ffi.set_source(..) statements in subscripts must move under "if __name__=="__main__", before ffi.compile(...). (Thus, subscripts will generate source when called locally, e.g. for testing purposes.)


Keyboard missing right click on Windows

Question: If you look at a Windows keyboard, there is a key to the right of Windows Key and to the left of Control key. It simulates a mouse right click on Windows. I recently purchased a wireless keyboard which does not have this key. There is only a function key between right side alt and control, and there is no other key. Is there a way to setup a keyboard shortcut that will simulate the right click instead? THis way I could do right click at cursor using my keyboard.
Answer: You should be able to send the same command with Shift+F10.
AutoHotkey can also be configured to do the same thing.
Comment: @PseudoSu Thanks.  This info is not at all easily available in a google search.

Keyboard missing right click on Windows


sharing memory between two applications

Question: I have two different windows applications (two different people writing the code). One is Written in C++ and another one is in C#. I need some way how to share data in RAM between them. One must writes data and another one just reads the written data. What should I use to make it most effective and fast?
Thanks.
Answer: You can use Memory Mapped Files.
Here is an article describing how to use them.
Comment: This is not an issue since you can map multiple files.
Comment: They are limited to logical address space. (Max of 2GB in my case, although my RAM is 16GB)
Comment: Just FYI, page at the 2nd link is missing/disabled.
Answer: You can use Named Pipes.

A named pipe is a named, one-way or duplex pipe for communication between the pipe server and one or more pipe clients. All instances of a named pipe share the same pipe name, but each instance has its own buffers and handles, and provides a separate conduit for client/server communication. The use of instances enables multiple pipe clients to use the same named pipe simultaneously.
Any process can access named pipes, subject to security checks, making named pipes an easy form of communication between related or unrelated processes.
Answer: Use a Windows File Mapping Object which allows you to share memory between processes.

sharing memory between two applications


Digitally controlled audio fader circuit?

Question: I have two audio signals and I want to fade in one signal in just as the other signal fades out and repeat the process backwards and so on... I want to control the circuit using some digital means or voltage control, however the actual circuit should be analog.
Any suggestion for an affordable solution?
Answer: Or you can use digital pot chips like AD5242 series dual I2C digital pots, coupled with some op amps.
Here is a reference design for you:

simulate this circuit – Schematic created using CircuitLab
The two pots there is the digital pot chip AD5242BRUZ10 commanded by the Arduino. You can program the Arduino to handle MIDI interface and plug this into your professional audio system rack.
OPA4134 is a proper audio grade op amp but it is expensive. You can experiment with orders of magnitude cheaper but pin compatible LM324, or get rid of the two voltage followers and use the cheaper OPA134 audio op amp that is pin compatible with 741.
TL431 is a 2.5V reference chip used as a virtual ground here.
Comment: There's no zero crossover detection in this circuit so isn't there a click in the audio whenever you change the volume?
Comment: @PkP I have a virtual ground voltage at 2.5V so if you reference the signal to that point you have no zero crossing issue at all.
Answer: Updated answer 01/23/2017:
Maybe this is an answer:
Digital Optical Volume Control with LED and photoresistor (light to seperate circuits, optical pot)
Using light to control the 'fades'/volume of each channel by using a LED and photoresistor(s). You can simply control the LED with an Arduino. Because of the LED is driven by PWM, you need to change the PWM frequency. See also example at my answer (and the reason why).
I made some drafts/examples at my question, my question is about if there is component that combines the two. There is, called vectrols but they are very expensive. You can make your own, it's cheap! More info and pictures at my question and answer.
Changed and simplified schematic:

More info at my question:
Digital Optical Volume Control with LED and photoresistor (light to seperate circuits, optical pot)
Answer: Use a digital signal processor (DSP). Convert both inputs from analog to digital, multiply them with values ranging from 0 to 1, sum them together and feed to the DAC.
You can also use digital volume control ICs, such as CS3310 (http://www.cirrus.com/en/products/cs3310.html) but a DSP might even be cheaper in the end. Depends on the number of channels and what kind of ICs you can find.
Comment: I was looking for an analog approach here - analog circuit with digital control. I have a very basic 8bit MCU in the system and I would like to keep it that way.
Comment: @user: The point is a small DSP will be smaller, simpler, and quite possibly cheaper if you have it do all the digital stuff, compared to adding analog fading to a smaller processor.
Comment: @OlinLathrop - Can you direct me to a solution that would be under $3 and won't require investing in development tools or software?
Comment: @user: Low end DSPs for uder $3 are certainly available.  You already have a processor in there, so you gain a little more budget by replacing it with the DSP and having the DSP perform the existing processor's function too.  As far as firmware development, that's part of engineering just about any meaningful electronic product.  You are already doing it anyway.  Doing it in a upgraded processor instead doesn't change that much.
Comment: @OlinLathrop - Can you give me just a single example?
Comment: STM32f411 reaches $3.50 in quants, and a devboard would run $18, and the tool chain can be free.  I'm pretty sure you can break your price point if you search more than 2 minutes like I did.
Answer: PT2259 is an 8-pin 2-channel volume controller which utilizes  CMOS  technology  and  incorporates  the  I2C interface    control.    The    controller    features    an
attenuation  range  of  0  to  -79dB,  low  noise  output,  a high  degree  of  stereo  separation  and  requires  only  a small  number  of  external  components.  PT2259  is  an essential component for modern audio visual systems.


Theming views page and pagination

Question: I am new to drupal and views. I have successfully created views page and understood some basics of it and views theming. I have created a views page for content type(products) listing. Now on the views page i have successfully listed the products. and now i want to theme it and also would like to know how to do pagination for it?
Answer: You have to be a bit more concrete when you ask for how to theme a view. One thing to note is that views help you with template suggestions (names for templates) which is one of the most common and easiest ways to alter the output of Views.
Pagination can be setup from within the interfacer. There is a pager link you can click on to set that up, if you look around a bit I'm sure you'll find it. The location depends on the Views version you use.
Comment: Hello thank you for the reply. I found theme information helpful while creating theme for views. Now How can i list all the content in content type in layout i want? I created views template file views-view--products-list.tpl.php I want to know how do i loop through products and how do i show pagination.

Theming views page and pagination


LibGDX: Max number of textures?

Question: I've been developing a game targeted at android. I know not to think about program optimization until the project is finished, but I have to wonder how many textures most phones can handle safely without melting or murdering battery. I've seen that the max SIZE of a texture should be 1024 or 2048 pixels squared (I've been combining sprite-sheets into 1024x1024 atlas's) but I can't help but wonder if there is a limit to how many of these I can use at runtime. I understand it should depend on the GPU but what spec determines it?
Comment: You're only limited by memory as far as I'm aware.
Comment: GPU or RAM memory?
Comment: On mobile devices, it'll almost always be the RAM size - VRAM is included in system memory. Wherever it isn't included in RAM, it doesn't particularly matter as it'll be a high end device with dedicated VRAM (and lots of it).
Comment: Typical source of confusion are texture units which are something else entirely. I'd be happy to add this as an answer if that would help.
Comment: please do. So I should be able to load several 1080x1080 textures at once without a problem, assuming there's adequate memory?
Comment: 1080x1080 is an awkward size, but yes that should be fine with the majority of devices. I'll drop an answer here for you with more info on that too :)
Comment: If a usual phone has 2 gigs of memory to use for textures and your textures are 1024*1024 pixels (4MB exactly), that means you can have around 512 images loaded at once (if you don't have anything else there of course, so you should count with 256)
Answer: The only limit on texture count is memory
The vast majority of mobile devices (and desktops with integrated graphics rather than a dedicated graphics card) use a shared memory architecture where VRAM - that's RAM reserved for video - is part of system RAM. Textures used by graphics APIs are simply pointers to a block of VRAM; there's no artificial limits imposed by the APIs themselves.
A typical source of confusion here is there's a very limited number of texture units. These are circuits in the GPU hardware which can 'bind' to a particular texture and perform the sampling for us. Importantly though, the limit only applies to a single shader. In effect if a system has, for example, 32 texture units, then a single shader can use at most 32 textures simultaneously. Note that there is also another similar limit that affects how many textures a particular stage of the shader can use simultaneously (the textures per stage limit).
Quick aside note: A simple way to improve memory usage is to use texture compression. Most mobiles support some form of texture compression nowadays and many engines enable it by default (those texture units can sample straight from compressed data).
Texture size
Those texture units are dedicated pieces of hardware and as a result are physically restricted on the size of textures they can deal with. The circuits that perform sampling are designed to operate on images with a power-of-2 size. This is why devices have limited texture sizes, ranging from around 512 up, and they're always a power of 2. 1080 is an awkward size for an atlas as it's not a power of 2 (so the hardware might decide to upscale it all the way to 2048).
Answer: The limit depends on:

the phone's memory bandwidth
the GPU's cache size
how large (in bytes) the textures are
the phone's memory size accessible to the GPU
how much of the texture you're using per frame
what mipmap level is being used (if any)
how well ordered your draw calls are so the GPU cache can work effectively
how much opaque draws you have vs blend or alpha test (hidden surface removal)
what the screen resolution is
how complex the shaders are (bottlenecks?)
how busy the CPU is

It's not a question of how many. It's not a question of how large. It's a question of all those factors combined.
You could have 4000 16x16 textures displayed and a phone could probably handle that faster than four 1024x1024 textures drawn over the screen.
Both CPU and GPU share the same memory bus on most mobile platforms which means if one is using the bus to read or write memory the other has to wait it's turn.
So you can run a test and see that the GPU is fine drawing N triangles with AxB textures at a certain frame rate, and run a test for CPU speed, but when you combine both GPU (drawing) and CPU processing (audio, loading/decompression, physics, particles & 3D model animations) suddenly the GPU performance drops. Or it could be the other way around where the GPU has priority over the CPU to access memory, or a mix of both depending on the system.
GPU and CPU usually run in parallel but they still have to "fight" over memory access on a shared memory system.
Comment: The GPU cache *generally* contains shader code rather than textures so it doesn't come in here. It's worth mentioning that most of the above are performance based limitations rather than a hard limit. E.g. even if it has low bandwidth, you can still max out the VRAM's capacity with textures.
Comment: Also "4000 textures ..could probably handle that faster" is false; it would require lots of draw calls (+lots of bus stalls) as it would have to keep reusing the texture units.
Comment: The GPU cache contains both textures and shader code.It needs to have texture cached to handle compressed textures.
Mobile GPUs use tiled rendering which means the GPU first does hidden surface removal then process all the individual pixels. Every pixel in a tile having their own attributes, shader and texture pointer, and can end up having a different texture on every pixel. Before this happens every triangle is put in their tile bucket, often by the CPU itself. There's no "bus stalls" like on desktop. While the GPU renders the previous frame the CPU builds the next complete tile bucket list
Comment: You've referenced bus stalls in your answer ("wait it's turn"); Lots of individual images from main memory => lots of waiting. Tiled rendering doesn't come in either, as the GPU still has to bind its texture units, and it only has a small number of those (no way near 4000).
Comment: I'm talking about the total number of textures used, not simultaneously bound textures.
Comment: Where the only limit on those is simply the amount of VRAM the system can allocate. Virtually everything else mentioned in your answer affects performance only - a busy CPU does *not* affect the total amount of textures that can be created.

LibGDX: Max number of textures?


What is the difference between Greek zōē and bios?

Question: Ancient Greek has two words that are translated as life in English: zōē and bios. What is the difference between them? What are their cognates in other Indo-European languages?
Comment: I'd love to see a good answer myself, besides what I can find in Montanari, bios "life of a human; lifespan; biography" vs. zoe "life."
Comment: These questions now belong to Latin SE, which also accepts Ancient Greek.
Comment: The meaning of individual non-function words is definitely off-topic. If you need recommendations for a good dictionary we can probably help though.
Comment: C.S. Lewis's *Studies in Words* has a great chapter on "life" across languages, including ancient Greek.
Comment: @jknappen: the Help center says we should welcome questions about "any natural language from a linguistics point of view... a single word in relation to multiple languages or a single word/single language." This question asks about the etymology of two single words and their cognates. It also asks about the difference in meaning; perhaps that part is not so much in the scope of this site. But for the most part, isn't this a question about historical linguistics?
Comment: See βίος and ζωή in the Lexicon Gregorianum Online http://referenceworks.brillonline.com/browse/lexicon-gregorianum-online The entries are very detailed, thoroughly explained and with lots examples.
Comment: @curiousdannii Clearly this question is not language-specific. See the last sentence, and the answers which show clear linguistic engagement. (On the other hand, a question asking for a good dictionary *would* probably be an off-topic usage question, although it may depend on the kind of dictionary.)
Comment: @Keelan That close reason has been commonly used as a stand in for non-linguistic usage and etymology questions even if they involve multiple languages. But I'll soon begin a Meta discussion about the phrasing of a dedicated etymology question. Even so, I think this close reason fits. The final question just makes this ask two basically entirely distinct questions.
Comment: @curiousdannii this question doesn't just combine languages. Again, actually see the answers for what can be done with a clearly linguistic approach. There is something to be said for splitting this question up, but also much against it, in any case it would get a different close reason, and in the end what is the point years later? You made your point then, and there was no consensus. Leave it be.
Answer: These two words are actually cognate with each other; they show the differing reflexes in Greek of labiovelar consonants.
In the noun ζωή zōē and the corresponding adjective ζωός zōos, the initial ζ developed from a cluster with the semivowel y; the noun βίος bios shows the normal development of PIE *gʷ before the full vowel /i/.
The Online Etymology Dictionary's entry for the (English) prefix bio- also lists an assortment of cognates in other branches of Indo-European:

Sanskrit jivah "alive, living;" Old Persian *jivaka- "alive," Middle
  Persian zhiwak "alive;" Old English cwic, cwicu "living, alive;" Latin
  vivus "living, alive," vita "life;" Old Church Slavonic zivo "to
  live;" Lithuanian gyvas "living, alive," gyvata "(eternal) life;" Old
  Irish bethu "life," bith "age;" Welsh byd "world")

It also has the following note on the meaning:

The correct usage is that in biography, but in modern science it has
  been extended to mean "organic life."

This is supported by the definition of βίος in Henry George Liddell and Robert Scott's A Greek-English Lexicon, edited by Sir Henry Stuart Jones:

life, i. e. not animal life (ζωή), but mode of life

(accessed from the Perseus Digital Library on 15 February 2016)
Wiktionary describes the noun ζωή as a derivative of the verb ζάω, ζώω (meaning "to live"), and gives the verb's etymology as follows:

From Proto-Hellenic *ǰṓw-ō, from *gʷyṓw-ō, from Proto-Indo-European
  *gʷíh3w-oh2.

In Attic Greek inherited /w/ was lost.
Piotr Gąsiorowski explains in the comments here how βίος and ζωός developed from the same Proto-Indo-European root:

*gʷih₃w-ó- 'living' and *gʷíh₃w-e/o- 'to live'. The change *-ih₃- > *-jō is an inner Greek development (parallelled by similar changes in Tocharian and Armenian). It's known as Francis–Normier's law, or
  laryngeal breaking. Not everybody accepts it, but they really should.
  The 'life' root alone would be evidence enough for it. [...]
The Greek development of the inherited labiovelars is complex and
  differs from dialect to dialect, but the normal (expected) Attic
  reflex of *gʷ before *i and *ī is b, not d (though *gʷj yields z).
  Therefore, both βίος and ζωός are regular.
Answer: Regarding their meaning/usage during the "Classical" and "Hellenistic" period in non-technical literature, I would say ζωή refers the opposite of "death" in terms of existence, and is used for animals, plants, etc., with common overtones of transcendence, whereas βίος refers to human lifestyles and activities, which by metonymy would also relate to things need to sustain such "life."
Answer: In Christian theology the usage of the original greek words in the bible give way to the churches to interpret the message for congeragation members. FE. Jesus said he is the way, the truth and the life (ζάω). In this case ζωή differs from bios. ζωή refers to 1 to live, breathe, be among the living (not lifeless, not dead). 2 to enjoy real life. 2a to have true life and worthy of the name. 2b active, blessed, endless in the kingdom of God. Bios refers to just life as opposed to not being alive.
Answer: A partial answer regarding the meaning:
Ivan Illich writes in the essay "The Institutional Construction of a New Fetish: Human Life" published in the book "In The Mirror of the Past":
"The concept of life does not exist in Greco-Roman antiquity: bios means the course of a destiny and zōē something close to the brilliance of aliveness. In Hebrew, the concept is utterly theo-centric, an implication of god`s breath."
Answer: C.S. Lewis in Mere Christianity uses the word Bios to denote biological life and Zoe spiritual life:

The Biological sort which comes to us through Nature, and which (like
everything else in Nature) is always tending to run down and decay so
that it can only be kept up by incessant subsidies from Nature in the
form of air, water, food, etc., is Bios. The Spiritual life which is
in God from all eternity, and which made the whole natural universe,
is Zoe.


HIbernate ignore fetching data from OnetoMany field

Question: I would like to ignore @OnetoMany field in my entity. fetch data need to get actual fields but don't want to fire query to dependent table. But deleting data from parent table needs deletion from dependent table
I have tried @Transient that ignores but the delete is also being ignored. Is there any other option to tell JPA not to fetch data from childs table when i call the parent entity?
@Entity
Table(name = "User")
public class UserEntity implements Serializable {
    @Id
    @Column(name = "id")
    private int id;

    @Column(name = "SERIAL", unique = true, nullable = false)
    private String serial;

    @OneToMany(mappedBy = "serialBySerialId", cascade = CascadeType.ALL)
    private Set<UserActionEntity> userActionsById;

}

@Table(name = "user_action")
public class UserActionEntity implements Serializable {

    @Id
    @Column(name = "id")
    private int id;

    @Column(name = "action")
    private String action;

    @ManyToOne
    @JoinColumn(name = "USER_ID", referencedColumnName = "ID", nullable = false)
    private UserEntity userByUserId;

Comment: Can you post the source code?
Comment: @Christine added the source code
Comment: Where is the code that deletes the entity?
Answer: If you don't want to fire query to dependent table, you can use (fetch = FetchType.LAZY) on UserActionEntity property.
 @OneToMany(mappedBy = "serialBySerialId", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
        private Set<UserActionEntity> userActionsById;


Performance on joins in linq

Question: HI ,
I am going to rewrite a store procedure in LINQ.
What this sp is doing is joining 12 tables and get the data and insert it into another table.
it has 7 left outer joins and 4 inner joins.And returns one row of data.
Now question.
1)What is the best way to achieve this joins in linq.
2) do you think this affect performance (its only retrieving one row of data at a given point of time)
Please advice.
Thanks
SNA.
Comment: Which O/RM tool are you using? LINQ to SQL?
Comment: I wouldn't rewrite that stored proc in LINQ, unless you have a really good reason to do so
Answer: You might want to check this question for the multiple joins. I usually prefer lambda syntax, but YMMV.
As for performance: I doubt the query performance itself will be affected, but there may be some overhead in figuring out the execution plan, since it's such a complicated query. The biggest performance hit will likely be the extra database round trip you will need compared to the stored procedure. If I understand you correctly, your current SP does the SELECT AND INSERT all at once. Using LINQ to SQL or LINQ to Entities, you will need to fetch the data first before you can actually write them to the other table.
So, it depends on your usage if rewriting is warranted. Alternatively, you can add stored procedures to your data model. It will be exposed as a method on your data context.

Performance on joins in linq


Web video gallery

Question: I'm looking for a simple plugin to integrate a video gallery in a website. I prefer it to be based on flash rather than HTML5 (for browser compatibility) and it should play videos hosted localy.
Thanks in advance,
Alex
Answer: You could consider open-source solutions like: 1.JWPlayer: www.longtailvideo.com/players/jw-flv-player/(maybe the most used)
2.FlowPlayer: http://flowplayer.org/
3.FLV Player: http://flv-player.net/

Web video gallery


As a stage 4 vampire, how can I feed without getting noticed?

Question: I'm currently a stage 4 vampire in Skyrim. As soon as I try and sneak into a town to feed, I get spotted like a kilometer away, even with an invisibility potion. Nothing seems to work! I don't want to make a new character since I'm a pretty high level. Is there any way I can look for a place to feed without them noticing me!?
Answer: I haven't played vanilla Skyrim in a long time, but I'm pretty sure you can feed off bandits and so forth in the wild before entering town. You might have to kill off most of the camp, run away, wait until the bandit "resets" to his normal routine, then wait until he's asleep. Nom nom nom.
As pointed out in this answer, Dawnguard gives access to the Vampire Seduction ability so you don't have to wait until the bandit is asleep, but it's limited to level 10/20.
Edit: this page on the wiki says

Dawnguard removes this penalty and people will treat a blood-starved vampire like any other person.

I'm guessing you don't have Dawnguard or you wouldn't have this issue. Installing Dawnguard could be a solution if you want to buy it.
Comment: Thanks! I havent really thought about buying DLC's for Skyrim especially with all these new games coming, but I'll install it and again thanks!


Which server software can be used to robot remote control from a browser?

Question: I'm considering to make a Raspberry car robot with camera which can be controlled from a web browser (via WebRTC). Is there any services/SaaS/open-source-software which I can use for building networking (video and commands transfer)?
Comment: Is there a reason you want to do it with WebRTC? Would you be open to doing it another way, but still through a web browser?
Answer: You may want to try or use UV4L for this. It supports WebRTC and the server can run custom webapps. The UV4L software can be found at https://www.linux-projects.org . There are also examples and other tools useful for robot-specific applications. Unfortunately, it is not opensource, but it is free to use.


What limits length of wire connecting audio amplifier to speaker?

Question: Let's say I have LM386 or some other audio amplifier. What determines the length, resistance, capacitance and inductance (if L C parameters matter) of the conductor that carries the output of the audio amplifier to the speaker?
Comment: "The resistance will be quite tiny isn't it? Fraction of a ohm." That all depends on the wire. You cannot simply assume that it is insignificant. E.g. 28 AWG twin (copper) wire will have a capacitance of about 15pF/m, 0.43 Ohms/m (allowing for return path 2 x 0.21) and about 1.7 uH /m inductance. A mere 20 metres of 28 awg twin wire will produce a resistance of 8.6 ohms - enough to half the power to an 8 ohm speaker, the capacitance and inductance being insignificant to audio frequencies.
Comment: You fail to ask about the resistance of the wire which increases with length and is inversely proportional to cross sectional area. Perhaps its the resistance of the wire that is most significant.
Comment: The resistance will be quite tiny isn't it? Fraction of a ohm.
Comment: I have added the resistance add well
Answer: The primary limiting factor will be the series resistance of the wire.
Let us work with a speaker of 8 ohms.
If the connecting wire were 18 AWG it has a resistance of 0.021 ohms per meter. If you were to connect the speaker with 50 meters distance from the LM386 (for a total wire path of 100 meters) the wire resistance would be (0.021 * 100) = 2.1 ohms. In such instance over 20% of the signal energy from the amplifier would be spent in the cable as heat and the rest going to the 8 ohm speaker.
(2.1 / (2.1 + 8) = 20.7%
You can use this example to evaluate other wire sizes and understand the effects.
Note: For audio frequencies do not fall victim to the marketing efforts of companies like Monster Cables that would have you believe that you need 8 AWG copper cable with gold plated connectors to connect up an 8 ohm speaker. Conventional low cost 16AWG lamp cord is almost always more than adequate to connect speakers at a reasonable working / listening distance.
Comment: Nah. Monster Cable is for the poor. You need [this](http://www.doublehelixcables.com/store/index.php?main_page=product_info&cPath=7&products_id=17) to really enjoy an unsurpassed listening experience.
Comment: If the only concern you have is power loss to your speakers, then go with 18AWG wires. If audio quality is your primary criteria, then there are many more considerations, many of which can be dealt with by decreasing cable resistance, and making sure you don't have oxidizing intermetallic contacts (which will soon increase contact resistance and also potentially generate nonlinear galvanic potentials).
Comment: With an LM386 audio amplifier I doubt there is much consideration of the "audio quality". Then yet the huge amount of hype surrounding what people seem to believe in regarding their perception of "audio quality"!!!
Answer: If you really want to be serious about the subject, EAW do a calculator and Crest have a chart. I haven´t been able to find the calculator on the website, but it´s here, top of the list.
And the Crest table:

And Litz cable actually does work, especially for reducing losses at the higher audio frequencies, but there are other (cheaper) alternatives as well. They´re called graphic equalisers!  :)


Cannot find the chest while doing the Break of Dawn quest

Question: I found the Statue to Meridia, then went to find the chest, but here isn't a chest where the map marker points to: it is inside the Dawnstar Sanctuary for the Dark Brotherhood. Is there any way to fix this?
Comment: You don't have Meridia's Beacon yet?
Answer: It sounds an awful lot like this known bug:

Meridia's beacon may spawn in the Dawnstar Sanctuary, even if the Dark Brotherhood questline has been completed, making the chest containing the beacon inaccessible. In turn this forfeits the Oblivion Walker achievement and makes it impossible to finish the quest.

I suggest loading an older saved game and continuing from there.
Alternatively, you can use the console command player.addItem 0004E4E6 1 to add Meridia's Beacon to your inventory. Now you should be able to enter the temple.


armature weights not working

Question: This is the first time I had this problem. When I did automatic weights I had to redo the hands since in I had to clean up the vertices and the fingers were stuck together.  One the left hand I had no problems but the right hand I duplicated and mirrored and simply attached the hand.  I attached the bones and parented them, but when I move the bones it is moving other fingers not attached to the current bone.  I checked the vertex groups and they are .
Answer: I would try selecting all the vertex points you want to represent the right hand, and then press Ctrl + i  to invert the selection to the rest of the mesh, and press Remove to remove them from the right-hand vertex group, while the right-hand vertex group is selected and highlighted of course.

armature weights not working


About Navigation Breadcrumb Blogspot...?

Question: How important are breadcrumbs? I understand it is important for navigation but I'm not certain how important it is for SEO? Are there use cases where breadcrumbs do not help SEO - and therefore is not worth the time to set up and maintain?
Comment: At least for me it is not really clear what you are asking. Please try to be a bit more specific.
Comment: I'm voting to close this question as off-topic because it's asking about SEO and not UX.
Answer: First and foremost:
You should think about satisfying the needs of your users. No SEO argument should stand in the way of providing them with the tools they need.
With that in mind:
Breadcrumbs do highlight important keywords for search engines but most importantly they act as secondary navigation and help users know where they are within a website structure. Below is a quick list of benefits to your users:

Breadcrumbs show people their current location relative to higher-level concepts, helping them understand where they are in
  relation to the rest of the site.
Breadcrumbs afford one-click access to higher site levels and thus rescue users who parachute into very specific but inappropriate
  destinations through search or deep links.
Breadcrumbs never cause problems in user testing: people might overlook this small design element, but they never misinterpret
  breadcrumb trails or have trouble operating them.
Breadcrumbs take up very little space on the page.

Source: Breadcrumb Navigation Increasingly Useful

So, to answer your question:
Yes, it worth the time to set up and maintain.
Answer: I don't find the article I read which speak about this subject.
But anyway, It says (from a Google employee) that they will reward websites for the user experience comfort more than technical guidelines everybody's following.
And I think giving everything to the user is better (in business terms) than SEO (word of mouth, satisfaction, retention)


How do I update to Blender 3.0?

Question: I just found out Blender got an update and I'm still using 2.90.1. So how do I download it, or does it just automatically do it? And will I still keep all my current stuff I saved?
Answer: You'll visit:
https://www.blender.org/download/
Click the blue Download Blender 3.0 button and double-click the installer when it downloads to run it.

There is an option when you install the new version to migrate your 2.9 settings. If you have any add-ons installed, those will come over as well, but be careful: they can cause crashes if they aren't tested with 3.0.

How do I update to Blender 3.0?


Homeomorphism type of tangent bundles

Question: If two closed smooth manifolds are homeomorphic, are the total spaces of their tangent bundle also homeomorphic? I bet this is not true but I do not know any counterexample.
Comment: When you say "the total space of their tangent bundle" you mean the tangent bundles as manifolds themselves ?
Comment: Yes,I mean the total space as smooth manifolds
Answer: Yes, if two smooth manifolds are (PL) homeomorphic, then their tangent bundles are (PL) homeomorphic. And if two PL manifolds are homeomorphic, then their "tangent bundles" are homeomorphic. Something stronger is also true. Smooth manifolds don't just have a tangent bundle with fiber $\mathbb R^n$; they also have a tangent disk bundle with fiber $D^n$, which you can think of as vectors of length $\leqslant 1$ or as a projective compactification of $\mathbb R^n$. If two smooth manifolds are (PL) homeomorphic, then the total spaces of their disk bundles are (PL) homeomorphic.
First I will give an elementary argument to answer your narrow question. Then I will discuss the strengthening and the difficulties of the obvious/systematic approach, discussed in the other answer and its comments.
First, reduce the question from tangent bundles to normal bundles. The normal bundle to the diagonal $\Delta\subset M^2$ is the tangent bundle. Thus the question reduces to showing that if a smooth embedding $M\subset N$ is (PL) homeomorphic to another smooth embedding $M'\subset N'$, that the total spaces of the normal bundles are (PL) homeomorphic. The advantage of the setting of normal bundles is the tubular neighborhood theorem: a neighborhood of $M$ can be identified with the total space of the normal bundle. Applying the (PL) homeomorphism, this gives an open neighborhood of $M'$. Being open is a purely topological property, so this space can be thought of as a subset of either $N$ or $N'$. So we have made the normal bundle of $M$ live inside $N'$, which is the key step to comparing them.
A better version of the tubular neighborhood theorem is that one can choose a properly embedded tubular neighborhood and identify it with the space of normal vectors of length $<1$ and its closure with the space of vectors of length $\leqslant1$. Thus the boundary of the tubular neighborhood is a smooth manifold diffeomorphic to the tangent sphere bundle. Its image under the (PL) homeomorphism is not smooth in the other structure, but it still is a (PL) manifold. From here on, (tubular) neighborhoods are closed. Take a tubular neighborhood $A_0\supset M$. Then think of its interior as an open subset of $N'$ and take another tubular neighborhood $A_1\supset M'$. Switch back and take another just by scaling: $A_2=\varepsilon A_0\subset A_1$. Finally, scale the other: $A_3=\delta A_1\subset A_2$. So we have $M=M'\subset A_3\subset A_2\subset A_1\subset A_0$. A word of warning: $A_0$ and $A_1$ have different smooth structures, so the two scalings are very different.
The space between two tubular neighborhoods $A_0-\mathring A_1$ is a PL manifold with two boundaries, one the sphere bundle of the one normal bundle of $M$ and the other of $M'$. A manifold with divided boundary is called a cobordism. This one looks like a cylinder from the point of view of homotopy, so it is called an $h$-cobordism. Moreover, it is an invertible cobodism: if we glue together $A_0-\mathring A_1$ with $A_1-\mathring A_2$, we get $A_0-\mathring A_2=A_0-\varepsilon \mathring A_0$, which is just the sphere bundle times the interval. The middle $h$-cobordism $A_1-\mathring A_2$ has inverses both outside $A_0-\mathring A_1$ and inside $A_2-\mathring A_3$. By the usual argument that the left and right inverse are equal, the two inverses are (PL) homeomorphic.
Let us abstract this a little. Let $W$ and $W'$ be cobordisms between the same manifolds: $\partial W=W_0\cup W_1=\partial W'$. Further, assume that they are inverse cobodisms: $W\cup_{W_1} W'=W_0\times I$ and $W'\cup_{W_0}W=W_1\times I$. Then I claim that the interiors are cylinders: $W-\partial=W'-\partial=W_0\times \mathbb R=W_1\times \mathbb R$. Furthermore, if you just remove one end, they are still cylinders: $W-W_1=W_0\times [0,\infty)=W'-W_1$. This is an Eilenberg-Mazur swindle, just like $0=1-1+1-1\ldots=1$. Geometrically: $$W_0\times[0,\infty)=W_0\times I\cup W_0\times I\cup \ldots=(W\cup W')\cup (W\cup W')\cup\ldots$$
$$W\cup(W'\cup W)\cup (W'\cup W)\cup\ldots
=W\cup W_1\times I \cup W_1\times I\ldots
=W\cup W_1\times [0,\infty)$$
where all $\cup$ unions mean gluing on boundaries. Finally, boundaries are collared, so adding a half-open collar is the same as removing the boundary: $W_0\times[0,\infty)=W\cup W_1\times [0,\infty)$. Thus, $W_0\times[0,\infty)=W-W_1$.
Apply this to $W=A_0-\mathring A_1$, $W_1=\partial A_1$. Then $A_0=A_1\cup W$. Removing boundaries to get tangent bundles, the one tangent bundle is the other plus a half-open invertible cobordism:
$$\mathring A_0=A_1\cup(W-W_0)=A_1\cup W_1\times[0,\infty)=\mathring A_1$$

The $h$- or $s$-cobordism theorem says that in high dimensions $h$-cobordisms, as identified by homotopical properties, are invertible; and it parameterizes them by a specific group. We did not need this because we had direct access to the inverse cobordism.
But the $s$-cobordism theorem says that there aren't very many invertible cobordisms, so we have to wonder if the cobordisms were not just invertible, but already cylinders. Indeed, this is true: this is the strengthening I mentioned at the beginning, that it is not just the total spaces of the tangent bundles that are (PL) homeomorphic, but also that of the disk bundles.
The obvious technique is to suppose that PL or topological manifolds have tangent bundles, fiber bundles with fiber $\mathbb R^n$ and structure group (PL) homeomorphisms of $\mathbb R^n$ or $D^n$. Then the smooth tangent bundle would, presumably, be the topological tangent bundle, and so the two smooth tangent bundles would be the same topological tangent bundle. While the Kister-Mazur theorem says that topological manifolds have tangent fiber bundles, well-defined up to a contractible choice, I don't believe that they have disk bundles. In any event, the microbundle is inadequate for this purpose because it is not a fiber bundle; it does not have a total space. It is only defined up to equivalence. It is true that the tangent bundle is a representative of the PL or topological tangent microbundle, but if we have two smooth structures, equivalence between their microbundles doesn't immediately tell us anything about the total spaces. It just tells us that they embed in each other, as with the tubular neighborhoods.
I claim that PL and topological manifolds don't have disk fiber bundles, but they do have something that functions as the total space of a putative disk bundle. This substitute is the regular neighborhood. The regular neighborhood of a polyhedron is the closure of the union of all simplices touching the subset, in a sufficiently subdivided triangulation. It is a basic theorem of PL topology that the regular neighborhood is unique up to PL isomorphism, even up to isotopy. The regular neighborhood of the diagonal is thus a PL invariant of a PL manifold. The disk bundle of a smooth manifold is a regular neighborhood, so if two smooth manifolds are PL isomorphic, so are the total spaces of their disk bundles. Topological manifolds also have regular neighborhoods, but this is a more difficult subject. Since the $s$-cobordism theorem has reared its head, one should expect this to be on par with proving that topological manifolds have Whitehead torsion.
Answer: I am not sure if this is exactly what you are asking for, but this: https://math.stackexchange.com/a/477495/195021 answer and this: Examples of non-diffeomorphic smooth manifolds with diffeomorphic tangent bundle question could be of some interest.
Comment: The first link shows there are two homeomorphic smooth manifolds whose tangent bundle are not isomorphic as vector bundles, but I am not sure if they are homeomorphic or not as smooth manifolds.
Comment: @XiaoyangChen I don't know a proof but in the question from the first link it is claimed that for a homeomorphism $\phi:M_1\to M_2$ between smooth manifolds, the bundles $TM_1$ and $\phi^*TM_2$ are isomorphic topological fibre bundles (an argument given there is that they both are subbundles of the (topological) tangent microbundle). I think this implies that the total spaces of $TM_1$ and $TM_2$ are homeomorphic.
Comment: I checked the paper of milnor and think we should be careful when talking about tangent micro bundles as you need a Riemannian metric to identifying the usual tangent bundle with the tangent microbundle.
Comment: @XiaoyangChen I don't know this stuff but in that question is said subbundle, not identification
Answer: Ben gave a wonderful answer, but this is actually (much) easier in the smooth category. See page 50 of Guillemin and Pollack.
Comment: I don't see how this is relevant. The question is about homeomorphic manifolds. Clearly the central issue is that homeomorphisms can't be differentiated to give maps on tangent vectors.
Comment: If you could give a precise statement instead of a cryptic suggestion it would also be wonderful.
Comment: I know that the link is likely to clarify. It's just convenient to include a statement. For instance, Ben started his answer with a statement. It's quite pleasant and helpful. Actually, I have an idea what statement you mean, but it sounds so trivial that it's not worth an answer (namely that $C^\infty$-diffeomorphic manifolds have $C^\infty$-diffeomorphic tangent bundles).
Comment: @YCor The link is to the actual text from G&P.
Comment: @YCor they just point out that if $f$ is a diffeo, so is the induced map on the tangent bundles (you don't need $C^\infty$), which is why I did not retype this in.
Comment: If $f$ is a $C^n$ diffeo, then the tangent map $Tf$ is $C^{n-1}$-diffeo, isn't it?("diffeo" is senseless)

Homeomorphism type of tangent bundles


In SC 9.3 Marketing Automation Plan, will contacts go to the yes path immediately or wait until the time has elapsed?

Question: In Sitecore 9.3 Marketing Automation plan, I have the following Custom listener.  In this case, will the contact go to the yes path and continue as soon as it triggers the campaign and channel or will it have to wait until the 6 days elapse?
Answer: It will trigger the Yes path as soon as the contact triggers the Campaign.
The Marketing Automation will run(keep listening) for next 6 days as shown in the screen shot for all the contacts. Now if any of the contact triggers the Campaign then it will execute the Yes path
Answer: In the Sitecore marketing automation custom listener element, if a contact satisfies the rules or conditions, it will immediately move to the Yes path without waiting for the time mentioned in the Listen For field. But if conditions are not satisfied at that point of time, contact will wait and listen till the mentioned time and then after that time has elapsed, if conditions still not satisfied then contact will go to No path otherwise to the Yes path.
Now in your case: If the enrolled contact has not sent any email campaign or not interacted with any channel at the point of time when contact engages with the custom listener, then it will wait for 6 days otherwise it will go to the Yes path immediately.


View contract details in a Django application

Question: I'm trying to create Crowdsale using Ethereum. I've done everything from Token creation, to DAO creation, to Crowdsale creation in Ethereum Wallet. Now, I want my web app (built in Django) to be able to view details in the contract such as how many coins are left, how much is a coin in ETH, what is the goal in a Crowdsale. How will I be able to do this?
Comment: If you haven't yet, I recommend that you check out web3.py at https://github.com/pipermerriam/web3.py (I'm a contributor).
Answer: You have two options:

Run an Ethereum node, or find someone who will let you use theirs. (For example, Infura provide the use of Ethereum nodes as a service.) You can make queries against the blockchain via that node using pyethereum. This gives you a lot of flexibility to make whatever calls you need against your contract.
Use a service that gives you data about the blockchain via a REST API. There are several companies offering developer APIs, notably Etherscan. This may be simpler if their API supports the features you need.
Comment: Can I use Etherscan even to call contracts from the Rinkeby testnet?
Comment: Also, I can't see a function to retrieve the remaining amount for the ICO to succeed, do I need to read all the transactions in the block and add it?
Comment: an alternative to etherscan but more focussed on reading/writing to contracts: https://cinder.cloud/ethereum-contract-api
Answer: First of all you need to decide whether to query blockchain on client side or on server side.  In the former case you will probably need to use Web3js.  In the latter case you will need to use Web3.py.
Also, there should be some Ethereum node to connect to.  In case of client-side implementation it may be provided by your users, or you may use node from some public node provider such as Infura.  In case of server-side implementation you will need to either run node yourself or again you may use node provided by Infura or some other cloud node provider.


What is the 0x10 in the "leal 0x10(%ebx), %eax" x86 assembly instruction?

Question: What the function is of the 0x10 in regards to this LEAL instruction?  Is it a multiply or addition or is something else?
leal 0x10(%ebx), %eax

Can someone please clarify? This is x86 assembler on a Linux box.
Comment: It's a copy-and-add the way it's used here (with that simple addressing mode).  Related: [Using LEA on values that aren't addresses / pointers?](https://stackoverflow.com/q/46597055)
Answer: leal, or lea full name is "Load effective address" and it does exactly this: It does an address calculation.
In your example the address calculation is very simple, because it just adds a offset to ebx and stores the result in eax:
eax = ebx + 0x10
lea can do a lot more. It can add registers, multiply registers with the constants 2, 4 and 8 for address calculations of words, integers and doubles. It can also add an offset.
Note that lea is special in the way that it will never modify the flags, even if you use it as a simple addition like in the example above. Compilers sometimes exploit this feature and replace an addition by a lea to help the scheduler. It's not uncommon to see lea instructions doing simple arithmetic in compiled code for that reason.
Comment: Very nice explained for compiler ..really
Comment: In addition, as mentioned leal can be used to do arithmetic operations . But it does not set the control codes. So, should not be used for conditional jumps or conditional moves.
Answer: lea stands for "load effective address"; it is a way to use the sophisticated adressing modes of the IA32 instruction set to do arithmetic. The l suffix is a way to distinguish the size of instruction operands in the syntax of GNU as, that you have on your Linux box.
So, in short, yes, it's a kind of addition instruction. It can also handle multiplications by 2, 4, or 8 at the same time.
See also this related question (where they are using the Intel syntax to discuss the same instruction):
Answer: GNU as 2.18 docs
https://sourceware.org/binutils/docs-2.18/as/i386_002dMemory.html

AT&T: -4(%ebp), Intel: [ebp - 4]

and then the Intel Syntax is self explanatory.
More importantly, the docs also explain the general case:

An Intel syntax indirect memory reference of the form

 section:[base + index*scale + disp]

is translated into the AT&T syntax

 section:disp(base, index, scale)

where base and index are the optional 32-bit base and index registers, disp is the optional displacement, and scale, taking the values 1, 2, 4, and 8, multiplies index to calculate the address of the operand

Things do get a bit messy in AT&T when we omit some parts of the address, e.g. -4(%ebp), but with the examples in the docs we can easily deduce all the syntax cases.
To really understand what is going on, I recommend that you take a look at how instructions are encoded. This is a good tutorial: http://www.c-jump.com/CIS77/CPU/x86/lecture.html When you see that, it will become clear why some parts of the address may be omitted, and what each form will compile to.
Answer: To add to Nils response,
As a refresher, the addresing mode in IA32 assembler is generally of the form:
IO(Rb, Ri, s), where:
IO = Immediate Offset
Rb = Base Register
Ri = Index Register
s = Scaling Factor {1, 2, 4, 8}
So the effective address is computed as *IO + [Eb] + [Ei]s
leal looks similar to other instructions like movl, but it is a bit special.
Instead of reading from the source to the destination, it copies the effective
address of the source to the destination.
So it can be used to generate pointers for later memory references, and also
for basic arithmetic operations, as Nils pointed out.
For example:
let register %edx contain a value of x
leal 1(%edx, %edx, 8), %eax
will load the effective address of 1 + x + 8*x = 1 + 9x to register %eax.
In essence, the operation:
leal source, destination   =>   destination = address of source
If you're familiar with C, it is the equivalent of :
char * b = &a
where the address of char a is assigned to char pointer b
more examples:
Let register %eax hold value x, and register %ecx hold value y
leal (%eax, %ecx, 4), %edx  will assign the value x + 4y to register %edx
leal 0xB(, %ecx, 5), %edx will assign the value 0xB + 5y = 11 + 5y to %edx
leal (%eax, %eax,2), %eax will assign the value 3x to register %eax
Hope this helps


Not enough space in dmg file

Question: I created a password protected dmg file (http://www.hongkiat.com/blog/encrypt-mac-folder/) but when I try to add content to the mounted dmg file I receive a 'not enough space' message. I have enough space.. don't know what wrong. How to fix this issue?
Answer: I'm not 100% certain what's going on, but I suspect you need to empty your trash while the DMG is mounted.
OS X stores the trash in a hidden directory in the root of each mounted drive.  If you drag files from the mounted DMG to the trash, they won't actually be deleted; they'll remain in that hidden directory (inside the DMG) and take up additional space.  If you empty your trash, that will delete the hidden directory, and you'll be able to store more data in the encrypted DMG.
Comment: This could be the problem, but only if there are deleted items in the trash. The real answer is to increase the size of the image with the hdiutil command (see other answer on this thread for details)
Answer: I found the answer for my question:
<code>hdiutil resize -size 80m
</code>
You can use G instead of M to specify the value in gigabytes.
Comment: This is the right answer. The only thing to add is that you have to specify the path to the image file after the size.

Not enough space in dmg file


Is Napaka's Scepter from TOA a permanent magic item?

Question: Specifically when it comes to Adventurers League magic item count.
Comment: This is the one that is used to dust the stone golem?
Comment: It's on TOA p. 165, under the "Sarcophagus" section below "Treasure" for room 53, Crypt of the Sun Queen.
Answer: No.
Also, it can't be taken with at the end of the adventure.
From DDAL FAQ
While this applied to nonmagical items, it does indicate that treasure and equipment that can be kept will be listed in a treasure section.

Nonmagical Items. Only treasure and equipment
specifically listed under a treasure subheading can
be kept (and converted into gp) by the characters.
Items not listed under a treasure subheading may be
taken by the characters, but at the conclusion of the
session, such items either crumble to dust, break, are
lost, or are rendered useless—they can't be used,
sold, or otherwise kept.

From DDAL DMG
The general rule for mudane treasure

D&D Adventurers League adventure.
Gold and Mundane Treasure. Coin, art objects, trade
goods, and other found wealth are converted to a gold
piece (gp) value at the conclusion of a session, episode,
or adventure, which is then divided by the number of
characters in the party. Each character should earn an
equal share unless otherwise specified. As a general rule,
items and treasure can't be awarded unless it is
described under a 'Treasure' subheading.

The following indicates similar ruling for magic items.

A permanent magic item can only be
awarded if it, or the random magic item table it's rolled
from, is mentioned in the encounter in which it is found.

Since the scepter is not mentioned as treasure nor awarded from a table, it cannot be kept or sold after the adventure.


Date display field drupal

Question: I have created two content types A and B. I have a Date field in A which is referred in B. But in B I want to display the Date field separately i.e 3 different select list for month, year and day.
Answer: Using the Date API module (part of the Date module), you can do something like this...
<code><?php
$form['payment_expirationDate'] = array(
    '#type' => 'date_select',
    '#title' => t('Expiration Date:'),
    '#date_format' => 'm', OR  '#date_format' => 'y',
    '#default_value' => $expirationDate,
    '#date_year_range' => '-1:+10',
    '#required' => TRUE,
    '#date_label_position' => 'within'
 );
?>
</code>
The date_select type will give you select box form elements for your field. And the #date_format array key allows you to use a PHP date format string to control what select boxes appear and what goes inside them.
Reference

Date display field drupal


If $(X,\tau)$ has more than $1$ point and is $T_2$ and connected, do we have $|X| =|\tau|$?

Question: If $(X,\tau)$ has more than $1$ point and is $T_2$ and connected, do we necessarily have $|X| =|\tau|$?
Comment: A metrizable one: (if I'm correct it seems to me that all the examples given so far are not). If $I$ is any set of cardinal $\alpha\ge c$ fix any connected graph structure on $I$ (so it has $\alpha$ edges), and $X$ the corresponding 1-skeleton, with its geodesic metric. Then $X$ has cardinal $\alpha$ and has a discrete subset of cardinal $\alpha$ whose points have pairwise distance $\ge 1$, so the open $1/2$-ball around each such subset makes a different open subset and there are $2^\alpha$ open subsets. (Note: clearly a metrizable connected space with $\ge 2$ points has cardinal $\ge c$.)
Comment: Thanks for all these interesting examples, I am looking forward to studying them all in detail!
Comment: Thank you for this example - it would definitely merit a full answer (which I am of course happy to upvote)
Answer: The $\frak{c}$-long line is $T_2$, connected and size continuum $\frak{c}$, but has $2^{\frak{c}}$ many open sets, since there is a size continuum discrete subset.
The more familiar $\omega_1$-long line is $T_2$, connected (even path connected, also locally connected), and size $2^\omega$. There are at least $2^{\omega_1}$ many open sets, since there is a size $\omega_1$ discrete family (such as the centers of the half-open intervals used to construct the long line), and so you can place intervals around each of them as you like, making $2^{\omega_1}$ many distinct open sets.
If $2^\omega<2^{\omega_1}$, for example, if CH holds (but that hypothesis is weaker than CH), then the ordinary long line itself is an example. But in any case, the $\kappa$-long line is an example for every cardinal $\kappa\geq 2^\omega$.
Comment: The completed long line, with the point at $\omega_1$, would be compact Hausdorrf and connected, size $2^\omega$, but with $2^{\omega_1}$ many open sets.
Answer: Consider the topology on $\mathbb{R}^2$ generated by subsets that are open in some line from the origin. This topological space is connected, has the cardinality of continuum, and has $2^c$ open subsets.
Comment: This example is essentially like the star graph, with $\kappa$ many edges joined at a single point. There is a similarity with the long line example: with the long line, you have $\kappa$ many unit intervals joined end-to-end, but with the star graph, you join them only on one side, letting them otherwise float freely from one another.
Comment: is "line for the origin" a typo?
Comment: (any $\mathbb{R}$ linear space in place of $\mathbb{R}^2$ would also work, for examples of higher cardinality)
Answer: The density topology $\tau$ on $\mathbb{R}$ is also a natural counterexample. It consists of all (Lebesgue) measurable $X \subseteq \mathbb{R}$ such that every point $x \in X$ is a density one point of $X$ which means: Whenever $\{I_n: n \geq 1\}$ is a sequence of open intervals containing $x$ whose lengths decrease to $0$, $$\lim_{n \to \infty} \frac{\mu(X \cap I_n)}{\mu(I_n)} = 1$$
It is clear that $\tau$ is a ccc topology on $\mathbb{R}$ that extends the usual topology. It is also clear that every conull set is in $\tau$ so that $|\tau| = 2^{\mathfrak{c}}$.
Claim: (Theorem 3 in C. Goffman, D. Waterman, Approximately continuous transformations, Proc. Amer. Math. Soc. 12 (1961), 116-121) Every interval $I \subseteq \mathbb{R}$ is $\tau$-connected.
Proof: Towards a contradiction, suppose $X, Y$ are non empty members of $\tau$ that partition $I$. It suffices to construct a nested sequence $\{ (a_n, b_n): n \geq 1\}$ of intervals $(a_n, b_n) \subseteq I$ such that $a_n < a_{n+1} < b_{n+1} < b_{n}$, $b_n - a_n \to 0$ and $\mu(X \cap (a_n, b_n)) = 0.5 (b_n - a_n)$. Since then $a = \lim a_n \in I$ cannot be a density one point of either one of the sets $X, Y$.
To construct such a sequence of intervals, use the following facts.
(1) If $a < b$ are in $I$ and $\mu(X \cap (a, b)) = 0.5 (b-a)$, then both $X, Y$ meet $(a, b)$.
(2) If $a < b$, $a \in X$ and $b \in Y$, then for all sufficiently small $r > 0$, there exists $a < c < d < b$ such that $d - c = r$ and $\mu(X \cap (c, d)) = 0.5 (d - c)$.
(1) is trivial and (2) holds because for all sufficiently small $r > 0$, the functions $h:[a, b] \to \mathbb{R}$ defined by $$h(x) = \frac{\mu((x - r, x + r) \cap X)}{2r}$$ is continuous and satisfies $h(a) > 0.9$ and $h(b) < 0.1$.
Comment: Very nice explanation - thanks Ashutosh!
Comment: No problem. The following may be interesting:

(1) Does the density topology on $\mathbb{R}^n$ (for $n \geq 2$) preserve old connected sets?

(2) If not, is there another topoogy $\tau$ on $\mathbb{R}^n$ ($n \geq 2$) that refines the usual topology, has size $2^{\mathfrak{c}}$ and preserves old connected sets.
Answer: The Golomb space $(\mathbb N,\tau)$ (a "universal" counterexample to many questions), also gives a counterexample with $|\mathbb N|=\aleph_0$ and $|\tau|=\mathfrak c$.
I recall that the Golomb space is the set $\mathbb N$ of natural numbers endowed with the topology $\tau$ generated by the base consisting of the arithmetic progressions $a+\mathbb N_0b=\{a+nb:n\ge 0\}$ where $a,b$ are relatively prime.
It is well-known that the Golomb space is connected and Hausdorff. Since it contains a countable disjoint family of open sets (like any infinite Hausdorff space), its topology has cardinality $\mathfrak c\le|\tau|\le|\mathcal P(\mathbb N)|=\mathfrak c$.
In place of the Golomb space one can take any other countable Hausdorff connected space.
Such spaces have appeared in other questions of Dominic van der Zypen:
Is there a connected $T_2$-topology on $\mathbb{Q}$ that is coarser than the Euclidean one?
Is $\mathbb{Q}$ the continous image of a Golomb-like space, or vice versa?
Cardinality of a set of countable connected Hausdorff spaces
Continuous self-maps in the Golomb space that are neither increasing nor decreasing
Answer: This is probably overkill, but assuming the Continuum Hypothesis there is a connected Hausdorff space $X$ such that

$|X|=\omega$; and
$|\tau|=\omega_1$.

It is Example 2.1 in this paper.  http://www.ams.org/journals/proc/1994-122-03/S0002-9939-1994-1287102-2/S0002-9939-1994-1287102-2.pdf.  It's fairly clear from the construction that $\omega_1$ of the $U_{\alpha i}$'s
(the sub-basic open sets) must be different.
Answer: Here are:
1) a metrizable example.
Namely, consider a complete graph on $\alpha\ge\mathfrak{c}$. Its 1-skeleton, endowed with the geodesic metric with edges of length one, has cardinal $\alpha$ and has $2^{\alpha}$ open subsets (since for any subset of the set of vertices, the open ball of radius $1/2$ around this subset determines this subset.
2) a separable example.
Namely, to fix ideas choose $S=\mathbf{R}/\mathbf{Z}$. Start from $X=S^{\mathfrak{c}}$, which is separable. Choose $D$ a countable dense subgroup (e.g., generated by any dense countable subset), and $F=S^{(\mathfrak{c})}$, the finitely supported subgroup. Then the topological group $G=FD$ is a dense subgroup, is connected because it has the dense connected subgroup $F$, and is separable because it has the dense countable subset $D$ (beware that $F$ is not separable), and $|G|=\mathfrak{c}$. Using suitable inverse images of projections, we see that $G$ has $2^{\mathfrak{c}}$ open subsets.
(Of course, a separable metrizable connected space of cardinal $\ge 2$ has cardinal $\mathfrak{c}$ and the same number of open subsets.)


Pressure due the atmosphere

Question: Usually when we consider the pressure exerted by gas, there is nothing to do with the weight of the gas. On the contrary the atmospheric pressure is defined as the weight of the gasses. What is the difference here?
Comment: @JohnRennie I don't think this question is asking why gases have weight. Rather, it is asking why the weight is not always considered
Comment: If there was still a space for an (accepted) answer, I would rather say that the ideal gas theory doesnt need the gravity correction included. And if it does, then it is more complicated task. An example of such a task is calculation of equation for atmospheric pressure, density and temperature dependence.
Answer: This is actually a pretty interesting question.
For starters, it depends on the system you are analyzing.  Atmospheric gasses are basically an open system that stays together due to the force of gravity.  All the gas further down is supporting the weight of the above gasses.  The force of this weight on top pressurizes all the air based on how much mass is above it.  See for example John Rennie's linked possible duplicate to explain how it works on a macroscopic level.
In a closed container, we often don't consider the weight of the gas because the effects of the weight are minimal if the height of the container is not very large.  In a very tall container, the pressure would also be affected by the weight. The gas on the bottom would have noticeably higher pressure than the gas above, because the gas on the bottom has to support all the weight of the gas above it.
The existence of the container isn't important, what is important is how tall the container is.  If it is tall enough, than the weight of the gas will have a noticeable effect on the pressure distribution.  Technically any closed container in gravity will have this; but unless the container is very tall the difference is negligible.
Answer: when we say pressure exerted by gas we say about pressure exerted by gas on container due to collision of particles with wall of container when kept in closed container we use PV=nRT to define it here pressure due to weight of air is very small so it is negleted ( it is same case as variation of pressure in sound wave) but atmospheric pressure is due to weight of gas as there presdure due to collision of particle with ground can be negleted due to very small value

Pressure due the atmosphere


Could someone give me an idea on why my car won't go over 20 mph?

Question: I have a 2004 Volkswagen Jetta and it won't let me go over 20 mph at times but also after a little while it starts to drive normally. I'm confused as this is my first car and I feel like the place I took it to is trying to play me. Has anyone dealt with this problem before?
Comment: Possible the catalytic converter has failed and disintegrated, and the debris is blocking the exhaust. With the car in neutral, will the engine spin up to the max revs as you expect, if you blip the throttle? If it misfires and/or dies instead, that would suggest a blocked exhaust to me.
Comment: Welcome to Motor Vehicle Maintenance & Repair! Is the check engine light on? Did the place you took it to say there were any codes? If so, did they tell you what they are (the exact number code would be very helpful here). Also, until you get a direction, don't change out any parts ... I truly doubt this is a mass air flow (MAF) sensor from your description.
Comment: So you will be going 20mph, and when you press the gas pedal more, the car does not accelerate past 20? When this happens, does the car maintain a speed of 20mph, or does it feel like it the car starts to slow down?
Comment: When was it last serviced? Is the air filter blocked?
Comment: Assuming this is an automatic transmission, could it be a transmission in "limp mode" and occasionally (when it behaves normally) it's not sensing a transmission issue?
Comment: I actually had this problem with my very first car, I was such a stupid kid lol, I never even thought about preventive maintenance. My transmission fluid was so low that it would go past first gear, all I heard was vrooooom, and I was crawling at 20mph haha, I must of looked funny. After I sat for a minute and let it cool I could go faster, but it would always slow down again
Answer: I'd suggest checking your spark plugs/glow plugs and your ignition coils.
You can also buy a cheap OBD2 Scanner from EBay and an app to use it with on the Google Play Store. It's not the best but it can read any Fault Codes and tell you what it's for. You can then research the Fault Codes online and try and pinpoint where the problem is instead of going to the Garage and having them check 101 things. The App I use is called MotorData OBD and for the Scanner just go on EBay and type in OBD scanner
Answer: Sometimes you have to take the car back.  when you have an intermittent problem, there is a chance that it will not make itself known at the garage.  I would however take it somewhere else that can keep it a day or two and be able to drive it with a scope attached to the odb ii port.  While in an actual driving situation they should be able to identify any out of range readings.  It could be a number of things that can cause this and there is nearly zero chance of someone guessing the problem with the information you provided.  You could have the transmission going into limp mode for example and that locks you into second gear.  It could be a shorting wire on a coil.  It could be a broken vacuum line that is opening and closing at a crack.  There's just no way to know.  I'm guessing transmission though.  It has a solenoid pack on it and solenoids wear out.
Answer: Check your mass air flow sensor it may be dirty or bad.
It regulates air flow and fuel mixture to throttle body.
This will cause the computer to go into limp mode to protect. Motor. Get some cleaner and spray it clean see if that works if not replace it.
Comment: How does the MAF regulate the airflow going to the throttle body? Why are you sure this has anything to do with the MAF in the first place?
Comment: Here are some of the most common symptoms of a faulty mass airflow sensor:
The engine is very hard to start or turn over.
The engine stalls shortly after starting.
The engine hesitates or drags while under load or idle.
Hesitation and jerking during acceleration.
The engine hiccups.
Excessively rich or lean idling.


Doubt regarding Nyquist theorem for sampling analog signals

Question: If for an arbitrary signal H(f) = 1 for 300-f-3700 Hz; 0 otherwise, what should be the minimum sampling rate? 7400 Hz or 6800 Hz and why?
Answer: The minimum sampling rate you theoretically can reconstruct a signal from is different to the sampling rate that's convenient to use to reconstruct a signal from.
Nyquist (the theoretical rate) says >= 2*BW. As the bandwidth of the signal here is 3400Hz, then by applying sufficient signal processing, you can sample and reconstruct a 300Hz to 3700Hz signal using a real sample rate of slightly above 6800Hz.
However, it's a lot of hard work. For instance one way to do it would be to frequency shift the signal in a the analogue domain so it's symmetrical about 1700Hz, then sample with I and Q at slightly more than 3400Hz, which equates to more than 6800 real samples per second. A better way would be to sample at some higher rate like 20kHz or so, then use DSP to do the frequency shift and resample down to just above 6800Hz.
However, what's practically required is a higher sampling rate.
As we've seen, you can take the DC to 300Hz section out of the sampling equation. But it's hard work to do, and only accounts for 10% of the bandwidth. Far easier to leave it in, and sample at >= 2x the highest frequency, rather than 2x the bandwidth.
Secondly, if you want to approach the Nyquist bound of 2x, then the transition band of your anti-alias and reconstruction filters needs to approach zero width. Difficult with analogue filters, increasingly resource hungry with digital filters. Obviously (is it obvious?) you can never get zero transition width, exactly equal to 2x oversampling, you just spend reciprocally increasing levels of resources (multipliers and latency) to get closer and closer to it.
It's far better to choose a ratio well above 2, to allow those filters to have a reasonable transition band, and therefore a cheap and stable implementation. Telephone signals in the 300-3400Hz band use 8kHz. Audio signals to 20kHz use 44.1kHz on CDs/mp3s. However, increasingly, higher sampling rates are being used because it makes the filter implementation easier, especially as costs of storing and transmitting data come down, 48kHz on DAT and some mp3 files, 96kHz on many PC sound cards.
Comment: 2 x 3700 = 7400 according to my calculator -- so 6800 would not be enough.
Comment: @ghellquist Nyquist talks about bandiwth, not highest frequency. The bandwidth of 300-3700 is 3400, so 2x that is 6800. However, it's more complicated to reconstruct bandpass data than lowpass data, so most people do 2x3700 = 7400, which with 'plus a bit' becomes 8kHz for telephones. When there's only 300Hz to throw away at low frequencies, it's worth simplifying. But if you had (let's say) a PCS channel with 300kHz bandwidth and 2.1GHz centre frequency, you would always digitise at 2x300kHz plus a bit, than 2x2.1GHz plus a bit, the extra complication is worth it in data rate and volume.
Answer: In theory, 2 x BW as per nyquist. In industry, most people use 2.5 x BW. Hence for your case, the sampling rate is 3400 x 2.5 = 8500 Hz.
All sampled signal has sinx/x roll off. The reason of not sampling at nyquist is because the roll off is far too high at the band-edge.
You will need to compensate the roll of, either mathematically in waveform file or using hardare.

Above sinx/x roll off


What are good ideas for getting the party together at the beginning of a campaign?

Question: What good ideas have you used or seen to get the party together at the beginning of a campaign?  There's the tried and true having them meet each other as wagon guards, or in a tavern that's attacked.  What have you used or seen to get the party together and get things moving in a fun, fast, and effective way?
Comment: Idea generation/discussion type questions are off-topic for RPG.SE, they don't fit our Q and A style format very well, but we do have a list of forums we recommend where you can get this sort of feedback. http://meta.rpg.stackexchange.com/questions/5449/ive-been-told-my-question-is-better-suited-to-a-forum-but-where-should-i-go
Comment: A good way to improve your question is to ask for methods of producing ideas for ways to put the party together.
Comment: Try googling "d&d players characters meet", also see this question: http://rpg.stackexchange.com/questions/16788/how-do-i-get-my-players-to-form-a-pc-party-without-just-forcing-them-to
Comment: @JoshuaAslanSmith could this not, perhaps, be coerced into a good-subjective question? Like "What has worked for you, and why?" or "How did you come up with a good way to do this?" Like in this blog post: http://blog.stackoverflow.com/2010/09/good-subjective-bad-subjective/
Comment: Also see [How to: Create a good backstory for how the party got together?](http://rpg.stackexchange.com/q/10195)
Comment: Thanks for the feedback.  I tried to make it "good subjective" by beginning it with "What good ideas have you used or seen".  That seems pretty close to "how did you come up with a good way to do this."  I am still getting the hang of this stack exchange thing, I guess.  Thanks for all the constructive feedback.
Answer: At the time of this writing, my campaign has been running for over a year so I've seen some success with the method that I used to start things up. I had all of my party members come up with a reason that they wanted to go exploring to a certain new land in my campaign setting. Then, during the first session, the action started during a boat voyage (they were all on the same boat) and a crisis occurred requiring adventurers to leap into action to save the day. The party succeeded, so the authorities in charge of the voyage gave them some recognition in a ceremony and then went to that group when they needed help with additional tasks that required daring adventurers. My players were quite happy with this setup and mentioned to me that they preferred it over our standard "So you all notice that there are other adventurers in a tavern. Now go adventure." type opening. Since this was when 5e first came out, my party was quite pleased to jump straight into the action and start using the new rules.
To generalize this a little bit, you could get all of your players to come up with a reason to be at the place that the campaign will start, then during the first session introduce some crisis that they are the most qualified to solve, then have the people that witnessed their heroics treat them as a group and offer to pay them or provide services to them if they do some additional quests.
The crisis doesn't have to necessarily be combat. You could, for example, have everyone watching or participating in a circus and have a large fire break out. The party could attempt to save as many people as possible and assist with putting out some of the flames using skill challenges to determine success and failure while keeping things challenging, urgent, and exciting without ever having to make an attack roll.
Comment: I really like this.  What I think is good about this answer is the idea of asking the players to come up with why they are going to wherever.  Thanks!


Is there a direct upload to YouTube with PS4?

Question: So I am a sub account and I don't have a Facebook to download it to YouTube with. I don't have a capture card to use with my PS4 so I can't upload. I've checked the share stuff but couldn't find an upload to YouTube. Is there a thing I'm missing that you can upload to YouTube or do you need a capture card or Facebook?
Answer: At the moment, no, there is no direct link to YouTube.  However if you wish to upload a video in minutes to YouTube the process would be:

Ensure you have the video clip you wish to use displayed on the screen (this can be achieved by "Settings"-"System Storage"-"Videos" etc.) and also a flash drive inserted into the USB port.
Hit "Options" in your controller and a menu will slide in from the right-hand side.
Select "Copy to USB". Once the file is copied over, go to your PC or laptop and insert the flash drive.
Go to YouTube, log in, select "Upload a video", select the video clip and upload it.

Warning: If the "Share" button is pressed it only stores the last half hour of gameplay, this is why I would recommend hitting the share button instantly after you decide to save it.
P.S. If you wish to edit the video before hand I would recommend using the PS4's ShareFactory to edit the video, this can be downloaded for free from the Playstore.
Answer: It's possible now.

Connect your PSN account with your YouTube. Go to Settings > Sharing and Broadcasts > Link with Other Services > YouTube and enter your credentials there.
Record a video. Luckily, PS4 does everything for you automatically. It saves up to 60 minutes of your latest gameplay (this is configurable in Settings > Sharing and Broadcasts > Video Clip Settings).
You can use Share button on your controller to either save this recorded clip to Capture Gallery or upload it immediately (there will be additional steps to select video name, tags, privacy, see this YouTube support page for details). Later you can go to Capture Gallery, find your video and upload it using the same Share button.


Full House and 4 of a Kind in the Same Hand

Question: Texas Hold em - What are the odds of this happening?  I had a Q full of 10s and lost to four 10s.  It obviously was a bad beat because the 4th 10 was on the river, but I would like to know the percent chance of this happening?  Thanks
Comment: Cannot mark as dup as it does not have an upvote nor accept answer but http://poker.stackexchange.com/questions/6698/full-house-v-quads/6699#6699
Answer: The odds of you getting a boat are 2.60%
But that number is high as you can only get quaded if the boat has a set
If you are using the pair on the board to make trips then there are not two left to quad
From the boat there are 45 cards out (52 - 2 - 5)
The only way for you to get quaded is for the other hand to match the pair on the board
So the odds of getting quadded are:
(2/2) / (45/2) = 0.00101 = 0.1% = 989:1
Which also = 2/45 * 1/44
From an odds perspective you can deal the other hand last.  Either the hand puts blocks on the board or board puts blocks on the hands.  In a random draw order does not matter.
Once the board is out (45 cards remaining) there are only 990 possible hands for your opponent.  This is actually an easy one that you can do at the table 1/990.
Ironically if you have a set on a board with no flush or straight then you don't want to make boat.  The set of tens probably did not even know they needed the quad.