Equivalence principle and gravitons

Question: If gravitons exist, are they always detectible in any frame? I'm asking because if I'm in a freely falling frame in a uniform gravitational field, and I detect gravitons, I will no longer be able to say that my frame is equivalent to another inertial frame in which there are no gravitons. Is this line of reasoning accurate?
Comment: No, gravitons are not detectable in any frame. Take flat spacetime as an example, there are no reasons to expect an on-shell graviton detection without contradicting that spacetime is flat. On the other hand, accelerated reference frames obviously exist in context.
Comment: If gravitons aren't detectible in any frame, then where does gravity come from?
Comment: Gravity is well described by the  Newtonian theory and for large masses  by General Relativity. In both these theories  gravitons do not exist. They are hypothetical particles introduced in attempts to a quantized gravitational theory. Gravitational waves (detected by LIGO) will be composed of gravitons in a quantized theory. My answer here may help https://physics.stackexchange.com/questions/215173/what-is-the-difference-between-gravitons-and-gravitational-waves.
Comment: As it stands they wouldn't be detectable in any frame due to a conspiracy of nature, see [here](https://www.youtube.com/watch?v=8aR77s9RLck)
Answer: Before diving into answer this question, first let's acknowledge as discussed in the comments that the notion of "gravitons" is not needed to describe any gravitational observation to date. There are good theoretical reasons to hypothesize that gravitons are a good way to describe quantum gravity when the gravitational field is not too strong, but there is no direct experimental evidence the world works this way.
Any physical effect is detectable in any frame. However, the notion of an exchange of "virtual particles" is not physical (because virtual particles are a mathematical artifact of one way of thinking about approximate calculations in quantum field theory), and the right way to think about what is happening depends on the situation.
First, let's start with the case of uniform acceleration. Would a graviton be involved in this situation? Well, the geodesic equation is
$$
\frac{d^2 x^\mu}{d\tau^2} + \Gamma^\mu_{\rho\sigma} x^\rho x^\sigma = 0
$$
If you aren't familiar with GR, you can roughly read this as saying that the acceleration (second time derivative of $x$) is related to the gravitational field $\Gamma$. However, $\Gamma$ depends on you choice of coordinates. For uniform acceleration, it will be possible to select coordinates where $\Gamma=0$. In graviton language, you should be able to describe the process of a uniformly accelerating particle with virtual gravitons in some frame, but you will get an equivalent answer to a different frame where no virtual gravitons where created. In the lingo, any apparent effect from virtual gravitons in this case is "pure gauge", or fictitious.
If you had a legitimate scattering process due to exchange of gravitons (for example, this might describe bending of light by the sun), then you would see non-zero gravitational scattering in any frame. The gravitons in this process are virtual, not real, gravitons, which means they are properly interpreted as a mathematical artifact of perturbation theory and not a real physical particle. However, the gravitational effect is there.
To detect a real graviton, you would need to look at a process like a gravitational wave, except one with a very small amplitude. (Similar to how we detect photons by looking at very low intensity light). In particular, if the gravitational wave had frequency $\omega$, we would want the total energy contained the wave to be of order $\hbar \omega$. This is much smaller than gravitational waves that have been detected to date. However, in principle you could build a sensitive enough detector to see individual real gravitons.
Now, to make the story a little more complicated, actually if you dig into the statement "in principle you could detect a gravitation with a sensitive enough detector," it is not clear that it is true. For example, if you try to build a LIGO type interferometric detector to look for gravitons, the detector will collapse into a black hole before it becomes sensitive enough to detect gravitons. This question is explored in detail in Freeman Dyson's essay Is a graviton detectable. (See also https://arxiv.org/abs/gr-qc/0601043).

Equivalence principle and gravitons


JRE for 64-bit and 64-bit Java?

Question: FWIK Java can run on 64-bit system, no problem. I'd like to know how Java support 64-bit features, e.g., System.identityHashCode() returns a 32-bit int, it's common to see the object pointer (memory address) is returned. Should 64-bit Java returns long instead? If not, how would Java scale to 64-bit systems?
Comment: This seems more appropriate for StackOverflow.
Answer:
FWIK Java can run on 64-bit system, no problem.

Correct.

I'd like to know how Java support 64-bit features.

Java supports 64 bit in a way that introduces no behavioural differences.  A Java program will run on 32 bit or 64 bit platforms without change.  All of the primitive types are the identical, the class library APIs are identical, the bytecode formats are the same.  As far as the program is concerned, the only difference is that you can allocate more things before your heap fills up.

System.identityHashCode() returns a 32-bit int, it's common to see the object pointer (memory address) is returned.

Inaccurate.  What you see is a value that may or may not be related to the object's memory address at some time in the object's lifetime.  Even if it is a memory address, it can't be used as one.  There's no way to turn the int value back into a reference in pure Java.  (Even with JNI / JNA it would be highly unreliable ... so don't think about doing it!)
An identity hashcode is a "uniquish" number.  That's all.

Should 64-bit Java returns long instead?

No.  That would make the class libraries different for 32 bit and 64 bit Java and prevent the same code from running on either platform.

If not, how would Java scale to 64-bit systems?

It just does.  There are one or two "issues".  For instance array sizes and string lengths are limited to 32-bit int values.  These mean that you can't fully exploit the hardware; e.g. you can't arrays with more than 2^31 elements on a 64-bit JVM.  (But if you could, there would be compatibility problems between 32 bit and 64 bit JVMs and applications designed to run on the two flavours.)
The identityHashCode return type is not a real issue because the value is NOT guaranteed to be related to machine address, and you can't be used as a machine address either.
Comment: @Tim - tell him "using `cp -r`" :-)
Comment: My brother (bless him), is a BA and asked me how we were going to address the challenge of porting all our Java software to 64bit.
Comment: @Tim, tell him it just is a question of testing your application again with the 64-bit JVM.
Comment: Don't forget you have to double the license fee you pay Oracle for using Java
Comment: @Jaap only if you use the premium VM ( basically JRockit ) And it's not that useful for small servers and no clusters.
Answer: The basic understanding of the JVM is incorrect.
The behaviour of the JVM is very strictly defined in the Java Language Specification and the exact details of the underlying platform is irrelevant as long as the JVM behaves as specified.
Basically you can expect any well-written Java program to run on any JVM, being it 32-bit or 64-bit without any difference in behaviour as the JVM behaves the same.
The primary differences you need to be aware of between 32-bit and 64-bit on the same platform is

64-bit JVM's can access much more memory breaking the "around 2 GB"-barrier.
Memory usage for the same program is somewhat larger on 64-bit than on 32-bit.

In other words, your programs should run unchanged.

Note:  If your program happens to use native code you need to consider this a separate, new platform.  One example is using Eclipse SWT instead of Swing.

JRE for 64-bit and 64-bit Java?


Is Isaiah talking about the same person In Isaiah 42 and Isaiah 53

Question: -Verses proving your point
-Scholar/Expert opinion
Comment: Welcome. [How do I ask a good question?](https://hermeneutics.stackexchange.com/help/how-to-ask) 'Sharing your research helps everyone. **Tell us what you found and why it didn't meet your needs.** This demonstrates that you've taken the time to try to help yourself, ***it saves us from reiterating obvious answers***, and above all, it helps you get a more specific and relevant answer!'
Answer: As @Dottard points out, many scholars have addressed this and related issues. But by no means do they all agree that the Servant Songs are messianic.
British scholar Peter R. Ackroyd, writing in the Interpreters Bible, understands Isaiah 42 to refer to the nation of Israel. This agrees with the usual Jewish interpretation. Hans Conzelmann, in his book Jesus, wrote: "For the assumption that Jesus understood himself as the Servant of God in the sense of DeuteroIsaiah, there is no support at all in the sources." Nearly all Evangelical scholars, on the other hand, see all of the Servant songs as prophecies about Jesus. Indeed, this has been the attitude of Christian theologians generally until the 19th century.
The Catholic editors the NABRE take a middle path:

Whether the servant is an individual or a collectivity is not clear
(e.g., contrast 49:3 with 49:5). More important is the description of
the mission of the servant. In the early Church and throughout
Christian tradition, these poems have been applied to Christ.

Similar differences of opinion exist with regard to Isaiah 53. Those who see the Servant as representing Israel (he is called "my servant Jacob" several times) see these prophecies as referring to the same collective person, who suffers on behalf of humankind but will ultimately be God's agent to bring justice to the world. So too, many Christians see both passages as referring to Jesus: one passage speaks of his suffering, the other of his ultimate triumph.
Conclusion: Most interpreters understand Isaiah 42 and 53 to refer to the same person, but there is no agreement as to whether this person is collective (Jacob/Israel) or singular (Jesus).
Answer: Difficult to say if both passages relate to the same person / people – however, its unlikely to relate to Jesus as many would like to believe.  @Dan Fefferman above sets out nicely (as always) the Jewish & Christian position.
I say this for the following brief reasons;
Isaiah 42

9 - new things I declare;
[Jesus did not say he came to declare new things – said came not to change a 'jot' Matt 5:18]

11 - Kedar lives rejoice. Let the people of Sela sing for joy;
[Kedar is Ishmael son and Sela is a mountain in Medina – not relevant to Jesus or Issac]

13 The LORD will march out like a champion, like a warrior he will stir up his zeal;  with a shout he will raise the battle cry  and will triumph over his enemies.
[Jesus was never involved in any war and did not triumph over his enemies]

16 - I will not forsake them.
[Matt 27:46 Eli, Eli, lama sabachthani? that is, My God, my God, why hast thou forsaken me?]
More on was Jesus forsaken see: https://hermeneutics.stackexchange.com/a/62632/33268

Isaiah 53

53:5 But he was wounded ……
[wounded doe not = killed.  'wounded' is the better translation, even 'pierced' does not imply death]

New American Bible 53:9 He was given a grave among the wicked, a burial place with evildoers, Though he had done no wrong, nor was deceit found in his mouth.

Good News Translations:  He was placed in a grave with those who are evil, he was buried with the rich, even though he had never committed a crime or ever told a lie."

[ i) a number of different translations, also, some translations say 'his death' the Hebrew word Mawth / maveth  (maw'-veth) has been mistranslated, should read 'death' or at best 'in death' (symbolic)…]
[ii) Jesus was not given a Grave with the wicked and was not buried – he was placed in a tomb by himself.]

53:10 Yet it was the will of the LORD to crush him; he has put him to grief; when his soul makes an offering for guilt, he shall see his offspring; he shall prolong his days; the will of the LORD shall prosper in his hand.
[Jesus life was not prolonged 33years & he did not see his offspring]

Conclusion:
Although some of the servant songs relate to Jesus such as Isaiah 52, Based on the above 42 & 53 do not.  Some relate to passages about the current events at the time.
Answer: Isaiah 40-55 contain four so-called, "Servant Songs", all messianic, about various aspects of God's servant who brings about the redemption/salvation of others.  These servant songs are:

Isaiah 42:1-4
Isaiah 49:1-6
Isaiah 50:4-9
Isaiah 52:13 - 53:12 - the longest and most famous.

Numerous Bible students recognize these as Messianic such as:

https://www.gotquestions.org/Servant-Songs.html
https://journals.sagepub.com/doi/abs/10.1177/003463736806500405?journalCode=raeb#:~:text=Four%20passages%20in%20Isaiah%2040,%3A13%2D53%3A12.
https://en.wikipedia.org/wiki/Servant_songs
https://tabletalkmagazine.com/article/2019/10/the-servant-songs-of-isaiah/
https://bibleresources.americanbible.org/resource/the-servant-songs-in-isaiah
https://knoxepc.wordpress.com/2020/05/13/isaiahs-four-servant-songs/
etc

There have been countless books written about these servant songs and their fulfilment in Jesus Christ - the NT appears to allude to them a number of times.  See the above references.


What's wrong with being haughty?

Question: We find many times in tanach and chazal (eg Sota 5a) where humbleness is praised and haughtiness is condemned. I would like to understand why that is. A person can conceivably fulfill all the commandments of the torah, and be a genuinely good person while still being conceited. What is it about excessive self-pride that is so incongruous with Judaism?
Comment: Interesting definition (which is almost identically ambiguous). Why do you think haughtiness is not included?
Comment: And be a genuinely good person? Define good person.
Comment: @DoubleAA i mean not a m'navel b'reshus ha'torah
Answer: To every positive trait there is a flip side and vice versa. Character traits often have elements of good and bad to them. (Rambam:HaMada-Hilchos Deyos 1:3,4)
Giava AKA Haughtiness can be a path to piety as well as the undoing of it.
For example, if a person has so much pride as to say to themselves "I will not do this aveirah(transgression) because this is not who I am" then there is merit.
But, if someone acquires torah knowledge and wisdom and lords it over others as a status than that is an undoing of piety.
An example is when the Kohen Gadol (High Priest) Aaron would don the white robes to enter the holy of holies, he wore them as a symbol of humility, yet did not allow wearing them to give him a feeling of status as in "Look at me I get to wear the 'humble' clothes -which makes me special"
It's a slippery slope because Aaron knew who he was but he also did not allow it to manifest in his ego.
The ego is critical to creativity, self-expression and free will. Without those things we aren't complete people. We are supposed to want better things and be competitive but for the right reasons.
-But... let those things go awry and it can be almost idolatrous -(leading to having a quick temper which is compared to idolatry because a person forgets g-d orders things a certain way to every person)  -and can lead to narcissism and hedonism.
I hope that helps
Comment: Thanks for this answer and welcome to Mi Yodeya. Citing sources for the points you make would make this answer much more compelling.
Comment: Regarding Aharon, I was can cite Vayikarah, Kedoshim, and for additional sources I will follow up with the exact source in Perkie Avos, and a source I can't remember exactly -but I will find it regarding the duality of middos, (Tanyah?) I can Paraphrase Rabbi Jonathan Sacks Book  "To Heal a Fractured World" Ch1 -Faith as protest (I believe was the heading) where he cites dialog with Avraham and Moshe as testament to the nature of or free will. I admit, There is another mussar book, -I think "Gateways of the tzadikkim" that compares anger to Avodah Zarah. Avos also does, I believe.
Answer: Arrogance is perhaps the worst character trait, because the greater one think one is, the less greatness one ascribes to G-d, and to others.
So the consequence of arrogance is thinking one's accomplishments are due to one's own efforts rather than to G-d, leading one to fail to praise and thank G-d. It also causes one to think little of other people, getting angry and impatient at them.
In addition, arrogance leads one to trust one's own ideas, rather than in Chazal and the great rabbis of this generation. This leads to heretical ideas and neglecting observance.
Finally, if one thinks highly of oneself, one is less likely to try to improve oneself through improving one's character traits, Torah learning, and observance.
Answer: I would say that the torah was given on har sinai the 'smallest' mountain to show that haughtiness and Torah dont go together. It is also no coincidence that moshe rabainu was the most humble of men and only through him could the Torah be given.
The question was what is wrong with being haughty. So this answers it by saying he will not be able to learn Torah. Since torah and haughtiness dont go together.
Comment: @shulem Most views on any page on Mi Yodeya come from random internet searches, not our regular users. We try and be accommodating to them because they likely are less educated than us. Plus, as someone who has looked for many a source that I thought was obvious, I assure you you'll be surprised sometimes at what you find when you take the time to look.
Comment: You could [easily edit](http://judaism.stackexchange.com/posts/28178/edit) your explanatory comment into your answer. That, and maybe a source to support you, would likely garner several up votes.
Comment: And also, whenever a post is edited, anyone can change their vote. This is designed so that the voting score can be updated with the quality of your post. I know this site has its quirks and unspoken rules, but I promise you if you get used to it then it's a very powerful tool. Give us a try :)
Comment: Well I have edited it but not yet put in a source which I think is totally unnecessary here.

What's wrong with being haughty?


Sound Library Management

Question: Hi there,
I hope someone can help.
I have been kindly given a sound effects library containing 20,000 plus sounds.
The thing is, the sounds are indexed by reference of numbers; rather than naming each sound.
I have made enquiries about how best to access these sounds without having to actually play each sound effect to find out what they are.
It has been mentioned that there is some sort of database software out there that would organise and name the individual sound effects allowing easy access to each sound, but no one seems to recall the name of the software.
Can any body help with any pointers please.
Many thanks in advance.
Asteriks
Comment: Well for starters, who created the library? The person that gave  it to you? If not, will the original owner still be using the (commercial) library themselves?
If so, it might seem a very kind gesture of them to 'give' you a sound library with 20K sounds, but unfortunately it is illegal to use such a library. Could you elaborate on the specifics of this 'transaction'?
Comment: .....'elaborating on the specifics of this transaction'.....

I was given a computer with a hard-drive that has the files on it, many recorded by an associate.

I'm fully aware of the 'legalities' surrounding the use of other peoples 'sounds', and feel not the need to be drawn into any discussion that seems to imply some possible pre-conceived; wrong doing.

Thanking you Arnoud Traa for taking the time to respond, even though it contributed in no way to address the question posed in my query.

Asteriks
Answer: The Specifics of Meta-Data
Comment: Thank you spoons r better, for helpful response to my query.
Answer: This topic has been discussed before.  Search the site and you should find discussions about various database apps.
Comment: Thank you Chuck Russom, for helpful response to my query.

Sound Library Management


Why are transistors difficult to use in special cases such as >100 MHz operation?

Question: I have heard on good authority that transistors are difficult to use in certain cases, such as >100 MHz operation.  Why is this?  Are there alternate devices which might be preferable?
Comment: Dont cite me as good authority! I was meaning to imply that basic use of a transistor is very easy, as you go into more complicated situations, high frequency operation being an example, the design becomes much more complex. I can make a basic amp knowing nothing but the type of transistor(pnp, npn or such) with a couple of resistors and a multimeter for low frequency operation.
Comment: Lol Kortuk, you're one of the best authorities I know!!
Answer: You premise is flawed.
It is not that transistors are difficult above 100 MHz, it is that any specialized circuit will require appropriate engineering. Engineering high frequency circuits using any components requires particular attention to lead lengths due to the wavelengths of the frequencies evolved. Wavelength is inversely proportional to frequency. In fact for radio waves in space wavelength = (speed of light)/frequency.
If you think about it, virtually all FM radios, TVs, cellphones and internet wireless routers use transistors (inside of integrated circuits) these days rather than the tubes (valves) that used to be used. 100 MHz is in the FM radio band, and routers operate in the GHz range.
What does cause issues in designing high frequency circuits is that as wires between components become a significant fraction of the wavelength involved they start behaving more like transmission lines, antennas, inductors and capacitors. This is not a problem with audio circuits where the wavelength is enormous.
Other factors to consider include crosstalk (signals from one wire appearing on another where they are not wanted) and shielding.
Answer: Using transistor in High frequency will cause some problems , that engineer will have to work them out while designing .
First I will show the difference between BJT(as example, it also applies to other types ) transistor in low frequency & high frequency :
This is the model of BJT in low frequency with noise :

This the model in High frequency

The below figure will show you how many noise effects are added while the frequency increases

All of this will make it harder to design in high frequency ,
As Jonny mentioned you may also face the problem of "Cross talk " : crosstalk normally refers to a signal affecting another nearby signal. Usually the coupling is capacitive, and to the nearest neighbor, but other forms of coupling and effects on signal further away are sometimes important, especially in analog designs.
, & the problem of parasitic capacitance .
High-frequency circuits require special design techniques such as careful separation of wires and components, guard rings, ground planes, power planes, shielding between input and output, termination of lines, and striplines to minimise the effects of unwanted capacitance
So in brief: transistor operating in High frequency will face many problems
like (cross talk , noise , parasitic capacitance , parasitic inductance .. )
Resources for further readings :-
http://www.mbeckler.org/coursework/2006-2007/ee3101lab6.pdf
http://iroi.seu.edu.cn/prepare/Meeting/File/SODC/data/01%20M.Berroth.pdf
http://bmf.ece.queensu.ca/mediawiki/index.php/High_frequency_transistor_models
Answer: I would also say that at high frequency, may of the assumptions that are made for low frequency are not valid anymore.
Take this question: also an inductor, that you would expect to behave as a inductor (guess why?), at high frequency starts to show the behavior of parasitic effects like capacitance (oh my gosh it's the opposite!).
And transistors, if you look inside, are full of parasitic capacitances, since each interface between differently doped regions basically creates a capacitance. This is a big issue when designing high-performance circuits like microprocessors or RF circuits, but with discrete components the frequency at which these effects appear is much lower.
In general, in many cases circuit analysis you make the assumption of quasi-stationary signals to mean that the speed at which things are changing is low enough to consider them static. Increasing frequency, this approximation loses sense.


Distinction of del pezzo surfaces and weak del pezzo surfaces

Question: I am a bit confused about the definition of weak del pezzo surface. Can someone give an example that what kind of weak del pezzo surface is not a del pezzo surface?
Answer: A surface $S$ is del Pezzo if $-K_S$ is ample. It is weak del Pezzo if $-K_S$ is nef and big.
To get examples of (true) weak del Pezzos, remember that a del Pezzo of degree $d$ is the blowup of $\mathbf P^2$ in $9-d$ general points.
If $S$ is the blowup of $\mathbf P^2$ in points $p_1,\ldots,p_r$, then $-K_S=3H-E_1-\cdots-E_r$ (in the obvious notation).
So the trick is to choose the points so that $-K_S$ is nef and big, but has degree $0$ on some curve. For example, choose 6 points in $\mathbf P^2$ such that 3 of them lie on a line. Then on the blowup, $-K_S \cdot L=0$ where $L$ is the proper transform of the line. However, one can verify that $-K_S$ is still basepoint-free, hence nef, and has 4-dimensional space of sections, giving a birational map onto the image of $S$ in $\mathbf P^3$, hence is big.
Answer: The simplest example is the second Hirzebruch surface.


Buggy websites for Selenium testing

Question: I am looking for a buggy website to do functional testing with Selenium. The website needs to have some bugs in it. The wider the variety of tests I could do, the better. Could you suggest a buggy website, which I can test?
Answer:
Frankly speaking, I tried, learnt & play with automation test scenarios with amazon.com as my playground.
You can try a bug is fine but important for your learning is you try to automate interaction with multiple different web components. I found amazon is having enough components.
If you need few more test websites, have a look here
Answer: @Narendra Chandratre answer is great, simply exercising the different interactions is a good way to go.
Amazon is a good real website, but if you wish for something more focused, The Internet is a good resource (you can run it locally or use this hosted instance).
It has a long list of situations that cover most of things you will see in a website:

I have used it in my blog post showing some refactoring techniques for automation in testing.
Answer: here are a few websites or applications that you can practice functional testing with Selenium:

www.google.com - It is a simple and widely used website, you can practice testing on various elements such as search bar, buttons, links, and others.
www.amazon.com - You can practice testing on the shopping cart, product listing, user login, and payment page.
www.flipkart.com - You can practice testing on the shopping cart, product listing, user login, and payment page.
weather.com - You can practice testing on the weather forecasts, search functionality, and weather maps.
www.facebook.com - You can practice testing on the login page, user profile, and post updates.

These websites are commonly used, widely recognized and have a variety of functionality to practice testing with Selenium.
There are also websites that are developed specifically for people to practice automation testing. Some of the most commonly used ones include:

http://automationpractice.com/
http://the-internet.herokuapp.com/
http://demo.guru99.com/V4/
http://newtours.demoaut.com/
http://book.theautomatedtester.co.uk/

These websites offer various functionalities and different types of user interactions that can be automated, allowing users to practice their automation testing skills.

Buggy websites for Selenium testing


Travel insurance for someone residing in UK under biometric residence permit

Question: I am an American citizen residing in the UK under a biometric residence permit. My husband is a UK citizen and I have a national insurance number. Wondering if i need a special type of travel insurance to visit the US for a week or if any company will cover me?
Comment: Nobody knows if your company will cover you.  Generally speaking however, it's best to get the same travel insurance your husband has.
Comment: @pnuts, yes, that's right
Answer: I don't think any form of health insurance coverage is legally required to enter the US as a US citizen or, in most cases, as an alien so you don't absolutely need anything special.
The NHS has some information on healthcare abroad and a list of countries with which it has an agreement but, unsurprisingly given the local healthcare system, the US is not one of them. This means that if you want to be covered, you will need a private travel insurance policy. Since you are a resident, I think most UK-based travel insurance should cover you as well but reading the fine print is always a good idea (see comments).
Comment: Also it should be added that travel insurances sometimes do not have coverage in the country of nationality of the insured person, so the fine print of the travel insurance should be read.
Comment: There are some US Visa categories which require the holder to obtain health insurance for the US for the duration of the stay, though. So the first sentence of the answer does not always hold for aliens. Surely that is not of relevance in this case.
Comment: @DCTLib Thanks for your comments! If you have more details (like a list of US visas which require health insurance), I am happy to edit my answer further. Alternatively, don't hesitate to write a better answer yourself (feel free to build upon mine, I would probably delete it afterwards)!


Why does Ino help Odysseus?

Question: In Book V of the Odyssey, Ino saves Odysseus from drowning by giving him a magic veil.
Why? Ino is a water deity, I'd expect her to be aligned with Poseidon's wishes. What reason does she have to intervene in favor of the hero instead? Even Odysseus seems to be puzzled about this, and doesn't immediately accepts her help. He only uses the veil after Poseidon (ironically) makes it absolutely clear that there's no other option.
Answer: First, the expectation is misguided. Deities are not beholden to their "kings." This is no better represented than all the Olympians disobeying Zeus by sneaking into battle in the Iliad.
In real life, Ino-Leucothea was a goddess of the sea that the Greeks venerated, one of many that they tried to ask for good sailing. The sea was notoriously dangerous (see the last paragraph of Beaulieu's The Sea in Greek Imagination, and many gods and goddesses became associated with its safe passage (including Aphrodite and Dionysus). Sailors needed all the help they could get in those perilous waters, and who better than Ino-Leucothea, who jumped into the water only to become immortal? The Greeks, especially in later times, were fond of cultivating worship of mortals that had become gods by escaping death (or gods that somehow escaped the underworld, like Dionysus), hoping that in saving themselves, they held the key to unlocking salvation for other mortals.
Ino-Leucothea fulfills both of these criteria. Not only is she a sea goddess, and thus useful in helping sailors cross seas, she was a mortal who escaped death to become a goddess.
Answer: Because she wanted to help him. She just felt she had to intervene to make sure he was okay. She had compassion towards him and didn't want him to die so therefor she saved his life so she did not feel helpless.
Comment: Welcome to Mythology and Folklore! Could you expand your answer a bit?

Why does Ino help Odysseus?


Join Date and Time to DateTime in C#

Question: I am retrieving data from an iSeries where there is a separate date and time fields. I want to join them into a DateTime field in my C# project. I don't see a way to add just a time to a DateTime field. How would you suggest accomplishing this?
Answer: You can do this quite easily:
DateTime dateOnly;
DateTime timeOnly;
...
DateTime combined = dateOnly.Date.Add(timeOnly.TimeOfDay);

TimeOfDay returns a TimeSpan, which you then add to the date.
Edit (thanks to commenters below) - to be safe, use dateOnly.Date to ensure the date part only.
Comment: A word of caution to the viewer here that you must make sure that `DateTime dateOnly` does only contain a date otherwise, with a big enough TimeSpan, when you preform the `Add`, you will increase the day by 1!
Comment: @CodeBlend is correct, this happened to me.  The best way to cover yourself is to do: `DateTime combined = dateOnly.Date.Add(timeOnly.TimeOfDay);`
Comment: Good catch, @RodolfoDeLosSantos! I sent a request to update the solution to match your suggestion.
Comment: Slightly different example: to combine today's date with a TimeOnly time: DateTime combined = DateTime.Today.Add(timeOnly.ToTimeSpan());
Comment: Yet another example, to combine a DateOnly with a TimeOnly: DateTime combined = dateOnly.ToDateTime(timeOnly)
Answer: How are they being stored? Assuming that the date portion is being stored as a DateTime of midnight of the day in question and the time is a TimeSpan, you can just add them.
DateTime date = ...;
TimeSpan time = ...;

DateTime result = date + time;

Comment: this will only work if date variable has time part 00:00:00 otherwise time variable will be added on top of date and it will be unexpected result.
Comment: @batmaci Yes, that is specifically stated in the answer.
Comment: I think this one will work the best for me in this case. Thanks!
Answer: You could easily construct a TimeSpan from your "time" field.
Once you have that, just do:
TimeSpan time = GetTimeFieldData();
dateField = dateField.Add(time);

Answer: Datetime date = new DateTime(Date1.Year, Date1.Month, Date1.Day, Time1.Hour, Time1.Minute, Time1.Second);

Comment: using `Time1.Second`, you are loosing precision, eg. Time1 = TimeSpan.FromMillisecond(0.5);
Answer: My answer addresses joining two objects of DateOnly and TimeOnly in .NET 6:
DateOnly orderDate = ...
TimeOnly orderTime = ...
DateTime orderDateTime = orderDate.ToDateTime(orderTime);

Answer: You can add a TimeSpan to a DateTime and write something like this.
// inside consuming function
ISeriesObject obj = getMyObject();
DateTime dt = getDate(obj) + getTime(obj);

private DateTime getDate(ISeriesObject obj)
{
     //return a DateTime
}

private TimeSpan getTime(ISeriesObject obj)
{
     //return a TimeSpan
}

Answer: This should do:
var output = date.Date + time.TimeOfDay;

or
var output = new DateTime(date.Year, date.Month, date.Day,
                          time.Hour, time.Minute, time.Second);

suppose that both variable date and time are both of Type DateTime
Comment: Using `time.Second` you missing the case where `time = TimeSpan.FromMilliseconds(0.5)`
Comment: @malat there is a comment about `date` and `time` are both of type `DateTime`
Comment: `var output = date.Date + time.TimeOfDay;` is the right answer. Using the constructor (your snd solution) will fail with the example I gave for `time`.
Answer: Note that adding the time to the date is not your biggest problem here. As @Reed Copsey mentioned, you just create a DateTime from the date and then .Add the time.
However, you need to make sure that the iSeries date and time (a Unix time most probably) are in the same representation as the .Net representation. Thus, you most probably need to convert it by adding it to a Jan 1, 1970 DateTime as well.
Answer: .NET 8 Update
As the Microsoft documentation suggests:
var theTime = new TimeOnly(11, 25, 46);   // 11:25 AM and 46 seconds
var theDate = new DateOnly(2015, 10, 21); // October 21, 2015
var theDateTime = theDate.ToDateTime(theTime);
var reverseTime = TimeOnly.FromDateTime(theDateTime);

Console.WriteLine($"Date only is {theDate}");
Console.WriteLine($"Time only is {theTime}");
Console.WriteLine();
Console.WriteLine($"Combined to a DateTime type, the value is {theDateTime}");
Console.WriteLine($"Converted back from DateTime, the time is {reverseTime}");

/* This example produces the following output:
 *
 * Date only is 10/21/2015
 * Time only is 11:25 AM
 *
 * Combined to a DateTime type, the value is 10/21/2015 11:25:46 AM
 * Converted back from DateTime, the time is 11:25 AM
*/

Answer: Cant you simply format the date part and time part as separate strings, then join them together? Then you can parse the string back to a DateTime object

Join Date and Time to DateTime in C#


Can magical intensities damage energy?

Question: Let's say I'm fighting somebody who can only be damaged by energy, and because of either an oversight or rampant pacifism, all I have are the Create [Intensity type goes here] spells to attack with.  Can these spells damage energy if I use them to attack with?
Answer: Since all the Create [insert element here] spells are of the effect type, they don't affect energy. As a matter of fact they are all manipulation of a physical phenomenom and have there own IP value (Frost, Heat and Electricity).
Answer: If you have access to the contents of the Arcana Exxet: Secrets of the Supernatural book then there is another potential option open to you should you happen to have at least 15 extra magic level to spend. Using the Metamagic in the Arcana Shepirah you could buy the Energy Control sphere under the Arcane Esoterica tree.  This grants the following ability:

The wizard can spend 10 Zeon points when casting any Attack spell to make it capable of damaging energy. Thus, even an Air Cut or Earth Spike would have sufficient mystical power to affect immaterial beings or beings immune to attacks not based on energy. Similarly, he can spend 10 Zeon points when casting any defensive spell in order to make it deflect energy, even when the spell does not normally permit it.
  Arcana Exxet: Secrets of the Supernatural pg. 27

While not purely RAW for this sphere to work on an 'effect' spell, it is a fully justifiable house-rule to adopt to cover spells that can be used to attack.
Comment: Please pardon the formatting, posting from mobile and don't know all the tags to clean it up.
Comment: I do have the Arcana Exxet as available source material, yes, though those 15 ML are a big tax for that sort of thing.  Yikes.  Formatting's fine, by the way.

Can magical intensities damage energy?


Powershell script to iterate all site collections and set another quota template

Question: I have a site collection with inside of it alot of sub site collection for each mysite instance. I would like to create a powershell foreach script which will set a quota template to each site collection. Can someone help me please?
Comment: What is your question?  Where are you stuck?
Answer: To use a quota template, you need to have it's GUID to be able to use it in the following second script. The other method would be to use -MaxSize and
-WarningSize attributes, which is usually what you use quota for.
Either you use the following script with the attributes:
$SPWebApp = Get-SPWebApplication http://portal

foreach ($SPSite in $SPWebApp.Sites)
{
    if ($SPSite -ne $null)
    {
        Set-SPSite -Identity $SPSite.url -MaxSize 4000000 -WarningSize 2000000
        $SPSite.Dispose()
    }
}

Or if you have a reference to the QuotaTemplate use the following script:
$SPWebApp = Get-SPWebApplication http://portal

foreach ($SPSite in $SPWebApp.Sites)
{
    if ($SPSite -ne $null)
    {
        Set-SPSite -Identity $SPSite.url -QuotaTemplate "12345678-90ab-cdef-1234-567890abcdef"
        $SPSite.Dispose()
    }
}

A quota template defines a space limit, the type of quota (hard or soft), and (optionally) a set of notifications that will be generated automatically when quota usage reaches defined threshold levels.
By creating quotas exclusively from templates, you can centrally manage your quotas by updating the templates instead of replicating changes in each quota. This feature simplifies the implementation of storage policy changes by providing one central point where you can make all updates.

References:

Create a Quota Template
Set-SPSite
Comment: what do I need to set in "
Comment: @KHA Preferrably a GUID referenceing the QuotaTemplate you want to use. Se my edited answer for more information.
Comment: Please respond how to get GUID of the QuotaTemplate? I am not able to get, search alot. Please help


How to find method name and return types in API testing?

Question: When creating a test for api testing how do I determine which method I should call(how to know method name) and and its return type(GET,POST,etc)?
For example : Do I have to talk to developers and get methods names for the task that I want to test?
Answer: This depends on how your devs developed the particular service under test. If we're talking about REST architecture, then there is probably WADL file exists that describes the interface you may use for interaction.
There is also a number of frameworks which are widely used in modern world to build up REST services. When devs build up a service they describe it in some declarative language that is converted to the service code. Those files are used for building test clients. As the example of such the framework you can refer to SWAGGER framework or alternatives.
Otherwise you have to ask your development to provide you the full specification of the service interface.


Are the cards in Zendikar vs Eldrazi standard yet, before Battle for Zendikar comes out?

Question: Is the new duel deck Zendikar vs Eldrazi considered standard before the Battle for Zendikar comes out? I have been playing it for a few days and I don't want to waste money buy more of those cards if I cannot play them in standard.
Comment: May be better if generalised to "Are Duel Decks released during a standard rotation legal during that rotation?", that way it will be distinct from the "is a deck legal" question, and will not become outdated. Zendikar vs Eldrazi can be used as an example.
Comment: I'd like to suggest changing the question to "How do I find out whether these cards *will be* in Standard?" (future tense). That would make it not a duplicate in my opinion.
Answer: No, those cards are not all in Standard. Some already are, some aren't yet, some won't be.

Some already are Standard: Read the Bones and others have been printed in Standard sets. You can use those.

The cards we know will be in Battle for Zendikar aren't standard yet. They will be after that set actually comes out and enters Standard rotation. Dominator Drone and others aren't available in Standard yet.

Some are old cards that might not become Standard at all. Like other duel decks, Zendikar vs Eldrazi contains many cards from past sets no longer in Standard. Butcher of Malakir and Corpsehatch have not been seen in Standard since the original Zendikar block several years ago. There's no guarantee these cards will become Standard at all.

If you're expecting to buy exclusively cards usable in Standard, Duel Decks are not the product for you. Buy those to actually duel with, or if you play a more open format like Modern or Commander.
Comment: Cards to note in particular are the dual lands in the decks, like Akoum Refuge, which is not in Standard and *definitely* won't be reprinted in BFZ.
Comment: What makes you say that Akoum Refuge definitely won't be reprinted in BFZ, at least more-so than any standard card?
Comment: @GendoIkari it already has several full dual land cycles and there are loads still in standard
Comment: @Gendolkari Fair question though, I've removed the speculation.
Comment: @GendoIkari We already know what the dual land cycle in BFZ is, and it isn't that. But I'll admit that it's possible that they'll print more than one of those. A better example would probably be Rocky Tar Pit, because Mark Rosewater explicitly said that they would not print fetchlands in this block.
Comment: @doppelgreener We have one full dual land cycle for BFZ.


ssh_exchange_identification: read: Connection reset by peer

Question: I am on OS X trying to ssh into a ubuntu 12.04 server. I was able to SSH in -- until abruptly stuff stopped working. I've read online to use the -v to debug this. Output is shown below. If I ssh into a different box and then ssh from that box to the server I am able to login. I have no idea how to debug this problem but would like to learn.
$ ssh -v me@server
OpenSSH_6.2p2, OSSLShim 0.9.8r 8 Dec 2011
debug1: Reading configuration data /etc/ssh_config
debug1: /etc/ssh_config line 20: Applying options for *
debug1: /etc/ssh_config line 53: Applying options for *
debug1: Connecting to server [IP] port 22.
debug1: Connection established.
debug1: identity file /Users/me/.ssh/id_rsa type 1
debug1: identity file /Users/me/.ssh/id_rsa-cert type -1
debug1: identity file /Users/me/.ssh/id_dsa type -1
debug1: identity file /Users/me/.ssh/id_dsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.2
ssh_exchange_identification: read: Connection reset by peer

So far (on advice of message boards) I have looked for a hosts deny file -- but there is no such file on my machine.
$ cat /etc/hosts.deny
cat: /etc/hosts.deny: No such file or directory

I have admin access on client machine but not on server.
Comment: The hosts.deny and hosts.allow file should be checked on the **server**, not on the client. Also, the system logs on the _server_ should be checked. If you don't have access to those either, you may want to contact the server admin to take a look.
Comment: Was a hosts.deny list that was filled by the admin with an automatic script. As I forgot my password at some point, I had a few unsuccessful attempts of logging in, which is when my IP was put on the hosts.deny list. So much for the productivity of overzealous security.
Comment: I would recommend starting an `sshd` listening on an alternate port, with verbose output, and providing the output when trying to connect to it. `$(which sshd) -d -p 23`. If you don't have the ability to do this, your options are pretty limited. Best bet is to get someone who has admin rights on the server.
Comment: Could it be that the administrator on the server restricted your access for some reason?  In any event, I might contact that person.
Comment: did you find a solution to it? what was the problem?
Comment: You might also want to check if your server is not out of memory.
Comment: When I got that error message from the client yesterday, the problem was an issue on the server that showed up as "read-only filesystem" errors, which we resolved by rebooting the server.
Answer: The abrupt change could be the result of a change in the configuration file on the servers sshd configuration, but you indicate cannot check or alter that without admin right. You can still try the following if the server's admins cannot be reached (in time).
Your log only indicates the local version string, you should check the versions of sshd running on the server and the intermediate machine.
If these versions differ (especially between the local machine and the server and less between the intermediate machine and the server) there might be some negotiation incompatibility, this has happened before in ssh. The solution used to be to shorten the Ciphers, HostKeyAlgorithms and/or MACs entries, either on the commandline (ssh -c aes256-ctr, etc.) or on in your /etc/ssh/ssh_config.
You should look in the debug information (from connecting via the intermediate to the server) for appropriate values as argument for the -c/Ciphers, -o HostKeyAlgorithms/HostKeyAlgorithms and -m/MACs commandline resp. ssh_config changes.
I haven't had this problem myself for a while, but IIRC when I did it was enough to manually force the Ciphers and HostKeyAlgorithms setting, after which I could update the server's sshd version and the problem went away.
Comment: In my case, the server `sshd` package was updated to a newer version and result in the incompatibility with my current `ssh` client configuration as you said. Clearing out my old `ssh` configuration files did the trick. This should be the accepted answer.
Comment: @chakrit how did you clean out your old ssh configuration files?
Comment: @Jonathan I mounted a recovery disk to do it.
Comment: @chakrit: if you could share what exact settings had changed, that would be really useful.
Answer: You may have been banned by fail2ban or denyhosts.  In such a case (and also to check it), if you don't want to bother with your server provider assistance, you need to log into your server from another IP address : e.g. another server, or a friend's home connection, or a wifi hot spot, or using SSH with TOR.
Once logged in, check that your IP address indeed appears in /etc/hosts.deny (on the server side).  If so, then fail2ban or denyhosts must be the culprit indeed.
See answers to this question for the procedure to prevent denyhosts to block your address continuously.  For fail2ban find your ip with iptables -L --line-number and unban you ip with iptables -D <chain> <chain number>, you check details on howtoforge.
You may want to add your IP address to fail2ban and denyhosts whitelists (respectively /etc/fail2ban/jail.conf, line ignoreip, and /var/lib/denyhosts/allowed-hosts, create it if needed (but beware that the path may be different on your distribution)) to prevent the issue to happen again.
Answer: On the host server, remove the ssh pub.key located here: ~/.ssh/authorized_keysfor your mac. Then tail -f /var/log/auth.log while you open another terminal and try to ssh again ssh -v me@server. If you are prompted for a password then there was a problem with your ssh key. If you are still seeing the 'ssh_exchange_identification: read: Connection reset by peer' response, then you should be able to identify what the problem is from the log entry in the '/var/log/auth.log' file after your failed attempt to login.
If you still failed to connect, post the logged entry from the auth file here and I'll revise my answer.
Comment: No need to delete SSH key in some cases. Go straight to tail -f /var/log/auth.log and check recent attempts.
Answer: This can happen if you have multiple machines on the network with the same MAC address (for example, if you make a copy of a virtual machine and forget to change the MAC).
Answer: I was faced with the same problem. I would open ssh session successfully but it would get reset after some time. When i tried to connect gain immediately i would get the error "Connection refused".
when i debugged the session i got this message at the time when the connection was getting reset
debug1: client_input_channel_req: channel 0 rtype email@example.com reply 1
debug1: client_input_channel_req: channel 0 rtype email@example.com reply 1
debug1: client_input_channel_req: channel 0 rtype email@example.com reply 1
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
  #0 client-session (t4 r0 i0/0 o0/0 fd 4/5 cfd -1)

debug3: channel 0: close_fds r 4 w 5 e 6 c -1
Read from remote host 10.x.y.z: Connection reset by peer
Connection to 10.x.y.z closed.
debug1: Transferred: stdin 0, stdout 0, stderr 100 bytes in 1029.9 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 0.1
debug1: Exit status -1

At this point i realized that there was an IP address conflict on the network. I changed to another address and problem was resolved
Answer: Your log means that server-side drops the connection. To find out the reason, you should consult server-side logs, they should show reason for disconnection. You should be almost always be able to find logs in /var/log/messages
I could guess that, as connection dropped just after client sent version number, server somehow threats client as incompatible.
Answer: I was getting this due to my ISP's nameservers in /etc/resolv.conf. These nameservers are often overloaded and if reverse DNS lookup fails sshd will drop the connection. I solved the problem by using more reliable nameservers, e.g. 220.127.116.11.
Answer: Since it hasn't been mentioned explicitly in an Answer, another way this error can appear is if a network-based firewall between you and the server has decided to block the connection. The firewall could have decided that there were "too many" connections from the OS X system's IP, and began blocking it. There were not yet "too many" connections from the other system, and so it was allowed.
The last message you received from the server is one that occurs before you even begin any authentication attempts, which rules out a large class of possibilities surrounding your account, key, or password.
Examples of such brute-force policies from a random sampling of vendors are:

CloudFlare: How do I use Rate Limiting to protect against brute-force attacks?
F5: Configuring brute force attack protection
FortiNet: creating custom IPS signature to detect a pattern rate - example to detect a Brute-force attack
Palo Alto: Prevent Brute Force Attacks
Sonicwall: How to block Brute Force and Dictionary attacks with SRA
Answer: I had the same problem but it turned out the cause was different: I was using wrong port.
On newer versions of ssh the error given is Connection refused or Bad port.
On older versions the error given is ssh_exchange_identification: read: Connection reset by peer
So when  you get such error check if port is correct.
Answer: I know this question is old, but I wanted to share some findings I had. Check if /var/empty/sshd on the server has appropriate ownership and permissions.
We had a chef script that was modified to update some directory permissions, but inadvertently updated the directory below the intended target, changing ownership of /var to an application user/group and changing the permissions to 775.
Answer: I ran into this exact error when trying to connect to all my remote hosts via the Wi-Fi bridge option on my Android device (Huawei P30 Pro). When I used the USB tethering option to share the same Internet connection, no problem.
Absolutely nothing else changed in the SSH configuration or options on the client or servers.
TL;DR: sometimes, nothing you can do.
Answer: In my case it was a different IP address prefix length.
The server had set 192.168.0.2/24 while client was 192.168.1.1/23. There was no connectivity issues whatsoever (for example cups printing works) until I tried to ssh.
Check ip addr show on both sides.


How can I repair this sewer cap?

Question: My home was built in 1959.  The clean out cap in the basement is 2.5" ID but it doesn't have threads.  It has 2 nubs (now it only has one) opposite each other that fit into two notches in the pipe.  I'm assuming you place it and turn to close it.  I found it today laying on the concrete floor, one nub is missing and the whole thing looks pretty corroded.  Can I replace the cap, I've been looking online and don't see any that look like mine, just threaded ones.
Comment: Is it brass? Only place I've seen those used is in fire systems. See http://www.firehosedirect.com/brass-pin-lug-2-1-2-nh-cap-with-chain/ Best bet is to take the cap to your local plumbing supply shop and see if they can get you a replacement. Using a threaded one may mean a lot of work because you have to change the fitting the plug goes into.
Comment: A photo might be helpful.
Answer: If the pipe itself is in good enough shape, you could just use a compression cleanout plug (sometimes called a mechanical cleanout plug) or a pressure testing plug:

There are quite a few different styles of these, but almost all of them work by compressing and expanding a rubber gasket inside the pipe. 2.5" might be hard to find at the big box stores, but they are available numerous places online. The main consideration would be finding one that would seat deep enough into the pipe that it would be beyond the notches for the old cap.

How can I repair this sewer cap?


RDMBS: Approach for efficiently accessing tree structure data held in a database

Question: Some details about the scenario:
 1. We have a MS SQL Server 2008 database which stores 'Resource' records in a table.
 2. Resources can have multiple child resources.
 3. A child resource can belong to multiple parent resources.
 4. Resources are linked to each other via an intermediary table, i.e. Resource -> Link -> Resource.
 5. There can be 'n' levels of parent\child relationships but realistically this is likely to be only 3 or 4 deep at most.
 6. Applications need to present a view of the data that shows the entire tree for a given parent and all its children where the children may be more the 1 descendant away from the parent, i.e. Resource (Parent) -> Link -> Resource -> Link -> Resource (Child)
 7. End users ideally need to see a real-time change in the tree based upon the actions they perform on resource relationships. By real-time I mean in the order of a few seconds as the change needs to reflected in the UI.
I've done some exploratory work using a series of views but having to use outer joins means they views can not be indexed and therefore may not scale well.
The next solution I'm looking at is creating one or more special tables that contain a flattened view of the resource trees. However this is unlikely to support the kind of real-time updates we require.
Has anyone dealt with a similar scenario?
Answer: It depends on how you need to access your trees.  If you need, for example, to pass in an ID and get that resource and all it's nested children, you might want to consider table valued functions, using recursive common table expressions.
Recusive CTE example


Problem with Chessbase 16 - Adding a subline via copy-paste

Question: Sometimes, in Chessbase, when I want to paste a game into another game (to reference it or to analyze a subline), a bug occurs: the pasted game completely overwrites the game I was working on. Why is that?
Nevertheless, I added the move to analyze before pasting the game to prevent it from being overwritten.
There are things where it works (most of the time), but sometimes, it doesn't work even if I restart Chessbase.
Answer: I've never used the typical copy/paste maneuvers in Chessbase. When I want to copy one game to another, I just drag one game into the other. The copy/paste action happens naturally. If you have an open database, just click and drag the game you want into the other game screen. It should be automatic. If you have two game views open, I think you can do the same thing. If you click the game and hold for a second, the mouse button usually changes into a plus sign, I think. Once that happens, you're good to go with adding the game.


Analytic continuation of instantaneous eigenstates of a time-dependent hamiltonian

Question: We are considering the instantaneous eigenstates of an analytically time-dependent hamiltonian and I would like to know how legitimate it is to extend them to the complex plane.
Specifically, our hamiltonian describes an atom or a molecule in an external laser pulse. Thus it includes kinetic energy terms, all Coulomb potentials, and a laser interaction, and it can be written
$$H(t)=H_0+\sum_{i=1}^N\mathbf{F}(t)\cdot\mathbf{r}_i.$$
Here $H_0$ can be assumed to be as well-behaved as necessary as long as one preserves the basic structure, but in general it's outside our capacity for exact solutions. $\mathbf{F}(t)$ is a vector-valued analytic (and if necessary entire) function of the time $t$ which is real for real times. We define the instantaneous eigenstates to obey the relation
$$H(t)|n(t)\rangle=E_n(t)|n(t)\rangle$$
in Dirac notation.
My question: Since $\mathbf{F}(t)$ can be extended to complex times, can the eigenstates $|n(t)\rangle$ be extended as well?
My specific worry is the following. One can always write, in this setting,
$$H(t)=T+V_1(t)+iV_2(t),$$
where $T$ is the kinetic energy and all three of $T$, $V_1$ and $V_2$ are hermitian and well-behaved. However, for nonzero $V_2$ it appears that $H(t)$ is no longer normal:
$$[H,H^\dagger]=[T+V_1+iV_2,T+V_1-iV_2]=2i[V_2,T],$$
which is in general nonzero since $T$ contains derivatives. It would appear then that formally none of the $|n(t)\rangle$ exist outside $t\in\mathbb{R}$. However, I would find such a strict cutoff somewhat strange - i.e., what if $V_2$ is nonzero but can somehow be neglected w.r.t. the other terms? surely there is some kind of a gray area around the real axis of some sort. Further, the existence and analyticity of the eigenstates for complex times, and in particular matrix elements involving them, are crucial to our results and physical intuition seems to indicate they should exist.
For completeness, we are considering in particular matrix elements of the form
$$\langle m(t_1)|U(t_1,t_2)A(t_2)U(t_2,t_3)|n(t_3\rangle,$$
where $A(t)$ is analytic in $t$ and hermitian for real times, $U(t,t')$ is the propagator and obeys
$$i\frac{\partial}{\partial t}U(t,t')=H(t)U(t,t'),\quad U(t,t)=\textrm{id},$$
and all three of the times involved, $t_1, t_2$ and $t_3$, may be complex.
Any insights will be deeply appreciated.
Comment: In the following simple case the answer is yes : $H(t) = -\frac{d^{2}}{dx^{2}} + (x-F(t))^{2}$
Answer: An operator can have eigenvectors without being normal.  Matters are complicated somewhat by having unbounded operators, but under some reasonable conditions you do have analyticity of eigenvectors for isolated eigenvalues.  See Kato, "Perturbation Theory for Linear Operators", http://books.google.ca/books?id=8ji2kN_D3BwC


QGIS Join vector point into polygon's

Question: I have groups of vector points (GPS points) in a number of layers in QGIS.  I would like to connect the points in each layer into polygons in each individual layer.  I have look hard, but can not find away within QGIS to do this ?
Answer: You need the "points to path tool" from the processing menu, I think you mean lines not polygons?
If you want a polygon use the buffer tool from VECTOR/GEOPROCESSING TOOLS menu to create a buffer around your points.
Comment: If the points make a complete ring (ie the final point is exactly the same as the starting point) you can use the `lines to polygons` tool to convert the lines into polygons.
Comment: Thank you ... just what I was after (magic) using the 'points to path' and 'lines to polygons' tools.  I can now mark all my Archaeology Field Project Trench in on the maps from my GPS points :-)

QGIS Join vector point into polygon's


Why does Rayleigh-Jeans law agree with Planck's at long wavelengths?

Question: Why does Rayleigh-Jeans law agree with the Plancks distribution at high wavelengths? I know mathematically, that at higher wavelengths, we can approximate the exponential in the denominator by $1+ \frac{hc}{\lambda k_bT}$ which gives back the Rayleigh's law, but I do not understand what is the Physics behind this. Why does the classical result agree at high wavelength, i.e. low energy.
Answer: Planck's postulate is, an electromagnetic oscilllator mode of frequency
$\nu$ can only have energies of $E=nh\nu$ (with $n=0,1,2,3,\dots$).
That means you have ladder-like energy levels, with small steps
at low frequencies, and big steps at high frequencies.
You can visualize these energie levels for some example frequencies $\nu$
and by how many oscillators they are occupied:

(image from my answer to another related question)
Doing the math, Planck derived the average energy of an oscillator mode
at temperature $T$ to be
$$E_\text{avg}(\nu,T)=\frac{h\nu}{e^{h\nu/kT}+1} \tag{1}$$
And now ansering your question:
At the left part of the image above (i.e. for low frequencies $\nu$,
or equivalently for long wavelengths $\lambda$),
the fine-grained energy levels can be well approximated by an energy
continuum.

This leaves the distribution of the oscillators among the energy levels,
and hence the average energy nearly unchanged.
$$E_\text{avg}(T) \approx kT. \tag{2}$$
You can derive this average either directly from Boltzmann's distribution
(like Rayleigh-Jeans did) or as an approximation of (1) for $h\nu \ll kT$.
Comment: Sir, exactly what I was looking for. Thankyou.  Just one thing I have to ask, in your answer to the related question you mentioned; you said that the distribution of the oscillators in the energy levels would be governed by MB statistics. But if this is quantum mechanics, shouldn't we use BE statistics?
Comment: @Shikhar To get the probability that the oscillator of frequency $\nu$ has energy $E_n=nh\nu$) you use the Boltzmann distribution: $p_n\propto \exp(-E_n/kT)$.
See [The Derivation of the Planck Formula](https://edisciplinas.usp.br/pluginfile.php/48089/course/section/16461/qsp_chapter10-plank.pdf) (page 9).
This is conceptually different from asking how many photons have an energy between $E$ and $E+dE$. There you use the Bose-Einstein distribution.


I am seeing Lord Narayana in everything. What does this mean?

Question: I am seeing lord Narayana in everything in my daily life. In every particle, in every tree , in every person who I see, in every animal, in every leaf, in every flower, in every food dish, in every computer in my office, in every building, on every road, in every vehicle, everywhere its as if Lord Narayana is everything. What does this mean ?
Comment: If this is indeed true, you are blessed. Please rush to a true guru. I recommend visiting Sringeri Jagadguru Mahaswami. Also these are intensely personal experiences and must not be shared with the world openly. I recommend that you delete your question here and reserve your questions for the true guru.
Comment: It means your previous life karma is giving you this realization of the truth....narayana parambramhan just seek his refuge and he will liberate you BG 18.66 http://www.bhagavad-gita.us/bhagavad-gita-18-66/. The essence of Purusha sukta is what you are experiencing  `namostwanataya sahasramurtayae sahasrapadakshisirorubahave shasranamne purushaya shashwate sahasra koti yugadharine namaha`
Comment: If this is true, you are really blessed. Very rare jivas get this oppurtunity. Go to true Guru and tell him your experiences. It's not even difficult to get a guru for you. Your Guru will guide you further.
Comment: Try to ask Lord Narayana "Who are you?" (I mean try to concentrate).
Answer:
I am seeing Lord Narayana is everything. What does this mean ?

I too agree with the views expressed by users in the comments section that indeed "You are very fortunate and a blessed person, as you have achieved the state of the mind which is very difficult to achieve, while we are mentally involved in our family life.
I have found some shlokas from Shreemad Bhagvad Gita as well as Shreemad Bhagvat Purana, where lord himself is describing your state of mind.

Bhagvad Gita -:
तानि सर्वाणि संयम्य युक्त आसीत मत्पर: ।  वशे हि यस्येन्द्रीयाणि
  तस्य प्रज्ञा प्रतिष्ठिता ॥६१॥
tāni sarvāṇi saṁyamya yukta āsīta mat-paraḥ  vaśe hi yasyendriyāṇi
  tasya prajñā pratiṣṭhitā
One who restrains his senses, keeping them under full control, and
  fixes his consciousness upon Me, is known as a man of steady
  intelligence. BG 2.61
  तदबुद्धयस्तदात्मानस्तन्निष्ठास्तत्परायणाः। गच्छन्त्यपुनरावृत्तिं
  ज्ञाननिर्धूतकल्मषाः ॥१७॥
tad-buddhayas tad-ātmānas tan-niṣṭhās tat-parāyaṇāḥ  gacchanty
  apunar-āvṛttiṁ jñāna-nirdhūta-kalmaṣāḥ
When one's intelligence, mind, faith and refuge are all fixed in the
  Supreme, then one becomes fully cleansed of misgivings through
  complete knowledge and thus proceeds straight on the path of
  liberation. BG 5.17

And here is what Bhagvat purana says -:

इति सर्वाणि भूतानि मद्भावेन महाद्युते ।  सभाजयन मन्यमानो ज्ञानं
  केवलमाश्रित: ॥१३॥
iti sarvāṇi bhūtāni mad-bhāvena mahā-dyute  sabhājayan manyamāno
  jñānaṁ kevalam āśritaḥ
O brilliant Uddhava, one who thus views all living entities with the
  idea that I am present within each of them, and who by taking shelter
  of this divine knowledge offers due respect to everyone, is
  considered actually wise. (True knower). SB 11.29.13
  अयं हि सर्वकल्पानां सध्रीचीनो मतो मम ।  मद्भाव: सर्वभूतेषु
  मनोवाक्कायवृत्तिभि: ॥१९॥
ayaṁ hi sarva-kalpānāṁ sadhrīcīno mato mama  mad-bhāvaḥ
  sarva-bhūteṣu mano-vāk-kāya-vṛttibhiḥ
Indeed, I consider this process — using one's mind, words and bodily
  functions for realizing Me within all living beings — to be the best
  possible method of spiritual enlightenment. SB 11.29.19

So from analysing above shlokas we can say that your current state is of Gyani who have realised  god in everything.
And proceeding towards final goal i.e. Moksha.
Comment: Narayana itself means Indweller so seeing Indweller in all is truly divine vision!
Answer: You are seeing Nārāyana everywhere outside is not a final accomplishment, (to see inside is,) rather it is a sort of divine welcome by Lord to you for journey to the ultimate Vasudeva tattva. (This is a descent of Shakti), You should intensely dive into spirituality & devotion to Lord Nārāyana, now material world should be of no use to you other than a play where you have to complete your play without any material desires. It seems Lord saying to you these words -

Just think of Me, be My devotee, worship Me, offer obeisance unto Me; certainly you will come to Me, I promise this in truth to you being dear to Me. BG-18.65.

Also,

Concentrate the mind upon Me, apply spiritual intelligence for Me; verily you will reside with I after this existence without doubt. BG-12.8.

This is not the end, Highest step yet to achieve from where there is no return. As also said in the Chāndogya Upanishad.

When a man's mind is his reins, intellect, his charioteer; He reaches the end of the road, That highest step of Vishnu. Valli 3.9.


How can I increase the size of a Windows 2003 NTFS partition?

Question: I have a very important server running Windows Server 2003 and my System partition is becoming too small, it's slowing down the machine.
I have already tried all the cleaning stuff and transferring some "unimportant softs" on the "Saves" partition but it didn't help much at all.
Is there a way to re-partition my hard-drive that will work on a 2003 Server, that's not too expensive and that could be used without turning the machine off.
If there is no other way, then I'll have to reinstall the OS, but it will have to wait for the weekend.
Thanks for your suggestions.
Answer: If it's the system partition you want to expand, as far as I know, there's no way around a reboot. Personally, I fire up a GParted Live CD [link] and resize the partition (as long as you have enough space on the disk).
If you're talking about a non-system disk, you can use diskpart.exe with no reboot. Proceed like this:

run -> cmd
diskpart
list volume
select volume (volume ID)
extend (size) (if no size specified, it's expand to the maximum)
Comment: be aware that GParted is quite slow on NTFS...
Comment: I found it was pretty fast actually, but it might depend on how much free space you have??
Answer: You can convert the disk to a Dynamic Disk, add more disks to the same pool and then add a second Dynamic Volume to the C:\ partition to increase its size.
http://www.petri.co.il/difference_between_basic_and_dynamic_disks_in_windows_xp_2000_2003.htm
Answer: The boot partition can be resized with Acronis Disk Director, from what I remember you do have to reboot if you re-size said partition.
Answer: Moo is wrong, I've checked, even if you convert to dynamic disk, you cannot expand the system volume. Only simple volume and spanned volume can be extended, though the system is simple volume, it cannot be extended. It will cause problem worse if you convert to dynamic disk, as no software can resize it. You'd better resize the partition in basic disk. I used disk director, it is the best server partitioning tool. If others have this problem, see this tutorial, then you'll know how easy to solve this problem by resizing with disk director
Comment: If you boot to a cd or usb and run diskpart, you can expand the system volume. You just can't expand is when booted from it. I've done this to many 2003 boxes.
Answer: Use ExtPart.  Free, simple and allows a live/online extend.
Has some limitations (NTFS format, Basic disk types), but even though it's a Dell driver, it works perfectly on other vendors' hardware.  I've been using it to extend the disks on a bunch of legacy VMware VMs (on HP servers) for quite a while and have yet to encounter any issues.
Comment: Great simple answer and can confirm it also works on Virtual PCs VHD's on Server 2003
Answer: If it is not using the entire disk, you could use diskpart.exe to extend it in size a bit more.  By the way your question is phrased, I am assuming that is the case.
If the disk is 100% used, then your only option would be to move the data to a larger drive.  This would not require a full re-install of the OS, but it would require down time.
The easiest way would be to clone the drive onto a large disk using something like Symantec Ghost.
Answer: If I remember correctly, diskpart will work only in special cases, namely when you have free space without any partitions on it, as it won't shrink other partitions.
Disk Director (or other tools like that) will happily do this when there is enough free space. It can take a lot of time though.
If downtime is  a concern, I would copy the disk onto another bigger one with a better disk layout, as you can do most of this in a running system, at least with Acronis True Image.
Also, when you do anything with diskpart, Disk Director or anything like that, remember to have a up-to-date and and tested backup as it's easy to do something fatally wrong, both for you and for the tools.
Answer: To increase the partition size, you may try diskpart command line, which is free and provides by microsoft, but has some disadvantages, it is not the best tool to change the partition size.
To increase the partition size with third party partition software, you just need to drag and move on the disk map to shrink a data partition, after that, extend the system partition with the unallocated space.
If the system partition is NTFS, you can extend it without rebooting the 2003 server to save time, see more details how to increase partition size on server 2003
Answer: Use EASEUS partition master.
But you need to reboot the server and leave it offline for 2-3 hours


Are extra dimensions timelike or spacelike?

Question: In special relativity there is a clear difference between spatial and temporal dimensions of spacetime due to the Minkowski metric diag(-1,1,1,1). In higher dimensional theories (10- and 26-dimensional string theories) does this asymmetry continue with additional dimensions being specifically time- or space-like or is there no clear difference?
Comment: related or possible duplicates: https://physics.stackexchange.com/questions/43322/intuition-for-multiple-temporal-dimensions https://physics.stackexchange.com/questions/43630/more-than-one-time-dimension
Answer: From Polchinski's String Theory, Chapter 1:

We want to study the classical and quantum dynamics of a one-dimensional object, a string.  The string moves in $D$ flat spacetime dimensions, with metric $\eta_{\mu \nu} = \mathrm{diag}(-,+,+,\cdots,+)$.

So all additional dimensions are spacelike.
Strictly speaking Polchinski is only talking about bosonic string theory at this point, but I believe the same applies to superstring theories as well.  (It's been a long time since I thought about this in any detail.)
Comment: @BenCrowell:  Nor did the question ask why the answer was X.  ;-)
Comment: @BenCrowell:  That's a fair perspective, and if someone wants to write an answer explaining the whys, I'll happily upvote it.  Mainly I wanted to ensure that the question didn't go unanswered, since the question seemed to be asking for a specific answer in the context of string theory.
Comment: This tells us that the answer is X, but it doesn't tell us *why* the answer is X.
Comment: This answer also suggests that the answer is not necessarily what you claim: https://physics.stackexchange.com/a/43637/4552 . The only way to clear this up and learn something would be to understand the whys, rather than just quoting Aristotle as an authority.


law of iterated logrithm

Question: Let $(\Omega, \mathcal{F}, P)$ be a probability space, on which
$\mathcal{F}_t$ is filtration satisfying general conditions. $W_t$ is
a standard Brownian motion. By law of iterated logarithm, one has
$$ P\Big(\lim_{t\to \infty} \frac{W_t}{t} = 0\Big) = 1 $$
This implies
$$ P\Big(\lim_{t\to \infty} \frac{t + W_t}{t} = 1\Big) = 1. \quad (1)$$
We have contradiction in this below. By Girsanov theorem, there exists
a probability measure $Q$ equivalent to $P$, such that $t+ W_t$ is a
Brownian motion w.r.t. $Q$. By law of iterated logarithm,
$$ Q\Big(\lim_{t\to \infty} \frac{t + W_t}{t} = 0\Big) = 1, $$
which implies
$$ P\Big(\lim_{t\to \infty} \frac{t + W_t}{t} = 0\Big) = 1, \quad (2)$$
since $P$ is equivalent to $Q$.
Why does this argument leads to a contradiction between (1) and (2)?
Answer: Girsanov's theorem tells you that on any finite interval $[0,T]$ you can find an equivalent probability that makes $t+B_t$ a Brownian motion. You just gave the proof that it cannot be done on the whole real line.
Comment: Or in other word this shows that $P$ and $Q$ are mutually sigular with respect to the $\sigma$-algebra $\mathcal{F}=\Vee_{t}\mathcal{F}_t$.
Answer: I am afraid that (1) is not correct, since the law of the iterated logarithm states that
$$|B_t|\approx \sqrt{2t\log\log(1/t)}$$
as $t\to0$. This yields
$$\frac{|B_t|}{t}\to\infty$$
as $t\to0$
Comment: sorry, I want $t\to \infty$ for all the above limits.
Those are typos.

law of iterated logrithm


Where can I download a list of all stocks traded on NYSE, AMEX, NASDAQ that includes dividend and dividend yield information

Question: Looking for a site I can download common stock information that includes dividend information as well as price.  I see reference to NASDAQ stock screener but I don't see that information there.
Comment: What is the purpose of downloading the data? Do you need to select few stocks, which pays dividends or do you need to download data from a lot of stocks?
Answer: I'll try to convey an answer as best as possible.
One method of screening for dividend paying stocks: If you do not know which stocks you want to work with, you can use a stock-screener like Tradingview stock screener. Here you can filter for dividend paying stocks (from high to low) and then single out your preferable exchanges (under the advanced filter section).
Downloading from Yahoo finance:
Let's assume that you've found your selection of stocks and now want to download the information (dividends and prices/adj.prices). This can be done on Yahoo finance. Search for your stock, go to historical data and specify your time-period. There should be a download button. Under "Show" you can filter for "dividends only" and download an excel spreadsheet with the dividends under the same period.
Downloading from Alphavantage.co: Assuming that you have a bit of coding experience, you can get even more stock-data from Alpha Vantage via Python or R. Here, you have "5 API requests per minute and 500 requests per day" as a free user and you can request for an API key for free. As an example, you can find the dividends and general time-series information of a stock (Apple is used as an example) via the function call:
Update 22-10-2022: TIME_SERIES_DAILY_ADJUSTED is now only for premium users.
<code>library(alphavantager)
library(httr)

av_api_key(YOUR API KEY HERE)

#Get time-series data (DAILY)
AAPL <- as.data.frame(av_get(symbol = "AAPL", av_fun = "TIME_SERIES_DAILY_ADJUSTED",
outputsize = "full"))
rownames(AAPL) <- AAPL$timestamp
head(AAPL)

#Getting general company information:
temp <- GET("https://www.alphavantage.co/query?function=OVERVIEW&symbol=AAPL&apikey=YOUR API KEY HERE")

AAPL_companyinfo <- content(temp)

#getting general information on Apple (disregarding basic information).
AAPL_companyinfo <- t(as.data.frame(AAPL_companyinfo[-c(1,2,3,4)]))
</code>
Which gives you:

In order to understand the API calls/functions, I recommend you to look at the documentation on the Alphavantage website and the "alphavantager" package description. In general, the av_get function returns the adjusted time-series including high, low, open,
close, adj.close, dividend amount, and split-coefficient. I used the "httr" package to scrape the content of the webpage in the "GET" function. This is just a JSON file and essentially, you could open the website, right-click and save as a .json file (as an alternative way to get the data).
Hopefully, this helps or give inspiration for alternative solutions/answers by others.
Answer: FINVIZ offers a number of screeners.  If you don't mind a close approximation of the dividend, you can use the FINANCIAL screener.  I say close approximation because it provides the percent yield in two decimals.  When you multiply the yield times share price, you may be off a penny or two from the actual dividend.
The screener includes a number of filters if you want to find specific lists (sector, optionable stocks, industry, country etc.).
If you want the precise dividend as well as the ex-div date, google dividend calendar.  I have found the NASDAQ and ZACKS to be reliable.


How to transition from underground schedule 40 PVC conduit to EMT inside building through concrete slab?

Question: I'm running feeder wires in 1-1/4" schedule 40 PVC underground to detached structure. I plan on using a 2" sleeve for the slab pour and a long 3' radius sweep elbow conduit fitting to bring wires  up from the trench into the building. I was thinking of using schedule 80 for the sweep, but everyone here still uses schedule 40 for above ground transition and no one is really stocking schedule 80. Feeders will run in conduit on the surface of the wall to a surface-mounted panel. I was planning to use 1-1/4" EMT for the inside run. What transition couplings are available for this? And should I make this transition just after the schedule 40 PVC emerges from the sleeve? Other suggests for a better way to do this?
Comment: I take it the EMT is because you're concerned about mechanical damage?
Comment: In my area, any electrical supply has schedule 80, and no big box or hardware stores have any, other than pre-formed small-radius sweeps. They don't stock straight sticks, or large radius sweeps, but the electrical supply houses do.
Comment: @ ThreePhaseEel Yes. Tight space and moving in a big, heavy water pressure tank.
Comment: @Ecnerwal I'm placing my electrical order soon.  I will check with them.
Answer: The most obvious options are a "conduit body" or a junction box. That also provides pulling access, which is likely useful at that point. That's what I'd do.
If you really don't need a pulling access point there (less than 360 degrees bend end to end from where you do have access) you can use a PVC to male threaded transition, a threaded coupling female to female, and an EMT to male threaded fitting. I have my doubts about it, but technically it works.
Comment: You can simplify that to a PVC *female* adapter with an EMT connector threaded into it
Comment: @Ecnerwal I really didn't want a junction because wall is already crowed with panel, control box, pipes. I only have two 90 degree sweeps (into and out of trench) and an offset to the panel box. It's the EMT to male threaded fitting I can't find. Is that set screws or compression on the EMT side? Does it have a name?


Is it possible to hit multiple enemies with a two-handed weapon?

Question: My players want to hit multiple enemies with two handed weapons, like cleave, but I can't find anything in the rules. The most I've given them so far is on a critical roll; They can hit the enemies if they are close enough to each other i.e. shoulder to shoulder. This seems fair on smaller targets like kobolds. I figured maybe Unearthed Arcana guidance might be out there, but couldn't find any. I'm guessing this was to simplify rules or maybe they will expand it officially later... Any ideas?
Comment: I'm looking for more of an official answer. This way I can prevent any arguing between players and myself. As they felt they could just 'realistically' cleave through multiple enemies that are 'hugging' for instance.
Comment: Are you asking *if* there is a way or how to make a way? The former is much relevant to the Stack while the latter may be better served discussing on a forum.
Answer: The DMG provides an optional rule called "Cleaving through Creatures":

When a melee attack reduces an undamaged creature to 0 hit points, any
  excess damage from that attack might carry over to another creature
  nearby. (DMG 272)

Its use is recommended when the PC-s face many low-level enemies to speed up fights. Using it all the time with heavy or two-handed weapons will give those weapons a clear advantage. I would advise to make it a feat (also see below) or to impose some kind of penalty on the attack or damage rolls if you want to make it a basic property of big weapons.
Also, the Great Weapon Master feat (PHB 167) lets you make an additional attack as a bonus action if you finish an enemy. It is similar in mechanics to the above mentioned rule and could be "fluffed" as a cleave.
Comment: +1. I've never played 5e, but read some stuff. Isn't there a feat called Great Weapon Master that does something similar?
Comment: @gaynorvader At first the similarity was not obvious to me, but yes, they are alike. I will add that.
Comment: @NautArch Well I certainly Appreciate it, It's a tough call so I'm going to try it out with them and get their thoughts. I think its best for my PCs since they have this strong desire for just the two handed weapons. Carrying over any left over damage is okay with me, on smaller enemies that can group-up closer together.
Comment: I see, this certainly does directly relate to the troubles I am facing. Especially since they are starting to lean towards wanting two-handed weapons specifically to do this.
Comment: Also, Thank you. When dndbeyond.com gets these guides out, it will make my DMing life so much easier to search for this.
Comment: @wieljer also, this is a Variant rule and not a standard one. You do not have to use it (my table doesn't... Hadn't seen it until today!)
Answer: Eventually, martial-type characters (including some Bards, Warlocks, and Wizards)1 get the ability to attack twice in one Attack Action - Fighters get even more. There are also ways to get a single attack as a Bonus Action, and a few very specific ways to hit multiple targets (the Ranger has a few).
This is a deliberate design aspect, part of the game's action economy. Allowing a martial character to hit multiple enemies with a single attack as a general rule would disrupt this balance, making them more powerful than intended.
"Cleaving Through Creatures" (DMG p272) is an optional rule that effectively lets you spread excess damage from a killed creature to another adjacent creature. As an optional rule, using it will affect the aforementioned balance. Whether or not this is desirable is a subjective question each group must answer.
1Valor, Pact of the Blade, and Bladesingers respectively.
Comment: @pokep …And all of those are fine points to make regarding having a feel for the game. However, when a phrase like *deliberate design aspect* is used and *not* substantiated with designer commentary that says *Yeah, we meant to do that* then it *is* up to the user to substantiate *in the answer* that it is a *deliberate design aspect* with his expertise and knowledge of the game. Which T.J.L. has now done.
Comment: Can the second 'graph be verified with designer commentary or is that your feel for the game?
Comment: @Hey I Can Chan  What exactly do you think requires "designer commentary"?  The (lack of) rule is clearly deliberate - "cleaving" is in the rules elsewhere, for martial and non-martial characters.  It is clearly part of the action economy.  And it clearly would make martial characters more powerful - and since the first indication of designer intent is the rulebook itself - more powerful *than intended*.  What is the sticking point that needs further clarification from the designers?
Comment: Great, thank you. This also helps me out. My players are new to DND so I have to point to rules and justify them. When I make a ruling on something, they want to do it all the time. So I have to be careful on what I allow.


Ender 3 V2 printing weak and messing up on the top 1/3 of the print

Question: I've had this Ender 3 V2 for about 6 months, and it has been printing great, but every now and then I will get a brittle messed up top on my prints. I can simply crush these tops by just touching them, they are super weak. The odd thing is it does not happen on every print.
Comment: What kind of material are you using? What are your settings? Do you have photos of the printed model? The more information we have, the better we can diagnose the problem and offer a solution.
Answer: Most likely this is a symptom of an under extrusion issue.
Could be heat-creep. Could be caused by a overly aggressive auto cooling setting where the minimum layer time is set so low that heat has time to climb up the filament and heat break causing a jam. Or other related reason such as the print speed is very low at a specific point in the print. This type jam can self recover with a temperature cycle of the nozzle so might not be noticed as the next print could be started without any intervention to clear it. The weak area of plastic could simplify be what oozed out of the nozzle after the jam.
Given the limited information I cant say much as to the cause.


What is the Best NoSQL backend for a mobile game

Question: What is the best noSQL backend to use for a mobile game? Users can make a lot of servers requests, it needs also to retrieve users' historical records (like app purchasing) and analytics of usage behavior.
Comment: Alot of browsergames use a documentdatabase like Mongo DB or Couch DB
Comment: As @Johnny000 mentioned, there are ones like MongoDB and CouchDB, that are widely used for that purpose.  I would add that you should consider developer time as well when making the decision.
Comment: You may want to consider a graph database that will help you manage relationships much faster. My favorite is OrientDB, which we use to manage a social network.
Answer: Some factors you might consider:
Developer familiarity: go with whatever you or your developers are familiar with.  Mongo, Couch, Riak, DynamoDB etc all have their strengths but all should do ok here, so rather than going for an unfamiliar solution that might be slightly better go for familiar and save a bunch of development time.
Ease of cloud deployment:  for example, if you are using Amazon AWS, then DynamoDB is likely an excellent choice.  Sure, you could use Mongo on AWS, but why bother?  Other cloud providers have their own preferred db, for example if you are using Google AppEngine, it makes sense to use BigTable or Cloud Datastore.
Your use case seems both well suited to NoSQL and not very challenging since your data has a natural partition by user.  I think you'd be technically ok with anything, which is why I'm mainly covering other factors.
Comment: So...Mobile App would write directly to DynamoDB or go via a web layer(REST API) that would write to DynamoDB? Any pros/cons or comments on that?


How can I show the variant of a device in a symbol in EAGLE?

Question: I am creating a device with multiple variants in EAGLE. The associated symbol should show the variant as well, so that it will be directly visible on the schematic.
I know how to add e.g. >VALUE or >NAME to a symbol and how to show attributes, too. But I can't find a way to show the variant name.
Comment: What is *variant* in your understanding? There're two things - technology and package, are you talking about package?
Comment: @Anonymous : In the device screen you can add multiple packages. Each time you add one, a variant is created, which can be named. E.g. a microcontroller variant with same package and pinout but more memory. Maybe I could use the technology field for this as well, but it would be more work to provide the attribute information eacht time.
Answer:
In the device screen you can add multiple packages. Each time you add one, a variant is created, which can be named.

I think names speak for themselves, but anyway let's look into them. For this just open 74-xx-little-us.lbr in the library editor and then device 74*1G00 as an example.

Package: you already know that it is footprint of the device on the board;
Variant: the identification of the package in relation to the current device;
technology: the intrinsic capability of the device.

Go to schematic editor, and import 74AHCT1G00DBVfrom the list of 74*1G00 from this 74-xx-little-us.lbr library.
This name 74AHCT1G00DBV is composed in the following way:

74*1G00;
AHCT put instead of * as technology;
DBV is added at the end as variant.

Now look into the library editor again. Right click onto package/variant line in the subwindow to the right, you will see that:

you can rename this selected variant (in other words, change package suffix);
you can add, remove or assign technologies for the device available in this selected package (variant).

In your example with microcontroller, which may have different RAM size:

create symbol for it, all packages/technologies/variants will have same symbol;
create packages this MCU is available in, add them to the list in library editor, for example N for DIP and D for SO;
add each package twice to the device, give each package in library editor's package/variant subwindow unique package identification, e.g. "KN" and "KD" for 16 KB RAM, and "YN" and "YD" for 32 KB RAM;
create technologies available, for example "42" for 3.3 V, and "46" for 5 V device;
name device as PIC*K22.

And in schematic editor you will have the following devices in the list available (of course depending on your technology assignments)
PIC42K22KN
PIC42K22KD
PIC42K22YN
PIC42K22YD
PIC46K22KN
PIC46K22KD
PIC46K22YN
PIC46K22YD

which will represent complete device identification marking.
The example above is (almost) out of the blue, because I like Microchip :)
(hopefully I did not make any logical mistake above, and I am sure you will figure out things yourself).
Comment: That helped my understanding a lot! Your solution will show up in the value field of the symbol then. Is there another option to show the devicename on the symbol? I would like to use the value field for e.g. resistance values too.
Comment: You already know >NAME keyword (in the *Names* layer) and >VALUE keyword (in *Values* layer). Resistor device, most probably, is already having its >NAME field defined, but it is just empty. Open *info* window on the resistor device in schematic editor, and define its value.


How does blackberry security features differ from standard android?

Question: How does the security features differ from standard android phones? Is the only difference the apps that can be just as well installed on a standard android phone in the play store or are there some additional layers?
Answer: Well, it depends on what you mean by "standard Android". There are some non-exclusive features and some special.

BlackBerry provides monthly security updates. This is not exclusive, for example Google and Nokia provide security updates, too. Some other vendors provide regular updates for a subset of their portfolio. Maybe some of them are even faster than BlackBerry. But BlackBerry phones are still much better than average there, because many vendors completely ignore security updates.

BlackBerry also provides state-of-the-art security features like verified boot, downgrade prevention, encrypted filesystem and so on. I am not sure about others in the industry, but at least, BlackBerry is likely not worse than others. I believe that some of those are now requirements and some are done voluntarily, so I guess BlackBerry is slightly above average there.

BlackBerry has also some visible exclusive feature: DTEK. Please don't confuse DTEK app with DTEK phones, BlackBerry makes some mess in naming. DTEK  is some security suite that contains not only a security checklist (that might advise you, for example, to require PIN for boot), but also allows you to manage permissions of all the apps (and revoke them even for pre-Marshmallow apps) and watch their usage (e.g., find apps frequently accessing location in background, or even be notified when some app accesses location in background). Of course, this is not just for location, one might be also concerned about other permissions.

AFAIR, BlackBerry has performed some kernel hardening, but I don't remember details.
Overall, BlackBerry seems to be a reasonable choice if you want a reasonably secure Android phone. It is not the only reasonable choice, as there are some other choices that might be good, too.