Wet blocks AFTER French drain and weep holes

Question: I had water leaking in my cellar from bottom of floor. Water was NOT on blocks at all. Now after French drains and weeping holes put in, the cinder blocks along the bottom of floor are wet. Will this damage my foundation, over time?
Answer: It sounds like your water table is very close to the floor level. It's not necessarily damaging to the concrete, after all hydration is what actually cures concrete and concrete peirs are largely unaffected even after hundreds of years sitting in water. Lumber and your possessions in the house are of a concern. I would suspect that you would benift from at least a sump pump and even better, a weeping system tied into the sump pump.
Answer: If the weep holes are admitting water, there must have been water in the block wall as well, and it was probably hidden by previous water sealing of the walls. Still, if the block wall had a course below the slab, the weep holes should have been drilled there when the perimeter had been removed to install the french drain, so this water wouldn't be visible above the slab.
Answer: Yes, the water leaking into your cellar can cause problems like mold, and decay of mortar, etc.
Sounds like the French drain was not installed BELOW the basement slab.
Water flows in the direction of least resistance. You have now installed a perf pipe that collects water by the wall...then, because the water has been collected above and next to the slab, it can seep into the basement.
Moisture is either coming up from below (a rising water table) or its coming from the surrounding ground water in the saturated soil.
If it comes up from a rising water table, it will enter the living space from below through the crack between the foundation wall and slab.
If it comes from the surrounding ground water, it COULD enter the living space through the wall, especially if the EXTERIOR side of the foundation wall is not sealed properly.
Either way the moisture enters the living space it will need to be collected and disposed. I think the best way to collect it is on the exterior side of the foundation wall in drainrock and a perf pipe laid 6"-8" BELOW the interior basement slab.
To keep the subsurface water from seeping through the wall, I recommend installing a moisture barrier on the exterior side of the foundation wall and install a 2" thick plastic mesh on the wall to allow water to flow down to the perf pipe. If dirt is allowed to be backfilled against the wall, the dirt could hold the moisture giving it a chance to seep through the wall.
Once collected it needs to be disposed by extending a solid pipe over an embankment or in a collection well and pumped away.
This may be the most expensive method of solving the problem, but it's sure to work.
Comment: No, moisture in a slab is not a problem other than mold and high humidity. I have had homes in multiple states with basements the oldest 1922 very wet basement. It had awesome French drains around the premier my dad bought the property before he passed I put them in  but there happened to be a spring  under a 6" slab that was poured prior to our purchase. A house older than my dad still stands today French drains did not help in this 1 case. What did help was an engineered coating on the slab that was prior to 2 part epoxy paint after that there was no problems, mom sold that when I enlisted.
Comment: @EdBeal I'm glad you agree with me that mold can be a problem. However, excessive moisture in a masonry wall can also be a structural problem. Just read this:   https://www.buildingsolutions.com/industry-insights/masonry-and-moisture-what-is-the-worst-that-could-happen?hs_amp=true  You say, "...moisture in a slab is not a problem other than mold and high humidity." Moisture IN A SLAB is not the question. The OP is asking about moisture in "the cinder block" WALL and FOUNDATION. Again, it's not the slab, it's the wall.


How is Vash able to transform his arm into a weapon?

Question: In Trigun, Vash the Stampede is able to transform his arm into a big weapon with which he makes a hole in the moon. Is that transformation ever explained? Did he acquire this power after the spaceship crashed or did he have it since the beginning?
Answer: I don't know whether you have read the manga, so the following may be somewhat of a spoiler, because it reveals Vash's true identity.
Vash is

a Plant. Plants are inter-dimensional beings that are tapped as a source of power and energy for the planet Gunsmoke. They are beings that can generate energy and even food and water based on environmental conditions. Plants were invented by humans, and are usually kept alive in light bulb shaped containers and used as a power source. Vash and Knives are independent Plants, meaning they can survive independently (other plants depend on being kept in a special environment in their containers) and even use their powers of their own conscious will. (1)

The ability to transform his arm is called Angel Arm, and it is a

 natural ability of all Plants. It may take various forms, but is most known for it's usage by Knives and Vash in a form of a cannon. However, in order to activate the ability, they need a catalyst (such as the pistols in the anime).
Comment: @Washu, unfortunately, it's prohibited to share links to illegal content on this site, so I can't give you any exact links to Trigun. However, most popular online manga readers (it's easy to google them up) will have Trigun.
Comment: Can you give me a link to read the manga... i cant find it :( @SingerOfTheFall
Comment: @SingerOfTheFall so this is what vash... does this scene ever explained in the anime? i remember watching the whole series of the the anime but never found anything about this. it just ended how knives and vash had a confrontation. and vash won. is that really the end?


Using Object Info/Random Node To Change Snow Mask Per Instance

Question: My journey into rendering snow continues, this time I'm using the Object Info node for the first time to randomize how much snow is on a tree model per it's instances. I nearly have it down, except I can't figure out how to prevent the trees from being completely white or have no snow at all. I started with a Color Ramp, but I think random just selects one of the colors that is in the Color Ramp? So I added a Map Range node, which almost fixed it, but when I get rid of a white tree, it makes the others have no snow, and vice versa. I tried a Math node after the random node, but that didn't seem to be the answer, either. I have a feeling I'm just missing the right node to put in here, so I welcome all of your immense knowledge. Thank you for your patience, and helping me, even when I'm helpless.

Blend File
Answer: The object info random output creates a differnt number between 0 and 1 for each object the material is assinged to.
Your map range node is starting at 0.2, I think what you want is the to min to be 0.2, to get a result between 0.2 and 1.
However that still would not solve the problem, since the map range node is just a monochromatic colorramp that computes faster, so having both is redundant.
My guess is that the outgoind color from the ramp is the amount of snow you're rendering. If you don't want any trees to be completely white, or don't have snow at all, simply don't choose black or white with any of the stops.
or: easier, but less control: set the map range to:

from min: 0
from max: 1
to min: 0.2 (min amount of snow)
to max: 0.8 (max amount of snow)

now take that value and multiply it with the z channel (blue) and you should get adjustable amount of snow.
Awesome solution from someone else:
https://pantarei.xyz/posts/snowline-tutorial/
Comment: Thank you, I now have a better understanding of the Map Range node! You are right, the output determines where the snow appears. However, I seem to be doing something wrong because there's no longer variance between the trees. I tried doing the Multiply with the Blue channel from the Separate Color node with the Map Range coming from the Geometry node, and then I tried doing the multiplication after the Add and Map Range node and same thing:  [Current Setup](https://i.imgur.com/y69cYMx.png)


She had to go there vs She had to have gone there

Question: I understand the grammar here (past infinitive in latter) but I do not understand what is the difference in meaning. Both seem to express the same, with the latter putting (in my opinion) more emphasis on the past aspect. But it does not help me..
Comment: All modals have two senses. One sense -- called [_Deontic_](https://english.stackexchange.com/a/276408/15299), refers to social obligations and permissions. That's what _had to go_ means here; there is an obligation to go. The other, called [_Epistemic_](https://english.stackexchange.com/a/411621/15299), refers to logical conclusions, and that's what the _had to have gone_ means here; there is a logical conclusion that she went.
Answer: The difference in tense means that the element of compulsion existed at different times and, therefore, acted on different people with different effects.
In the case of "She had to go there" there is an element of compulsion on the actor which existed prior to the action being taken and was the cause of the action being taken. Examples are:

She had to go to the hospital because she was injured
She had to go to the supermarket because she had no food in the house
She had to go to work for 10:00pm because that's when her shift started
She had to go to the probation office on Monday because it was a condition of her bail.

In the case of "She had to have gone" there is not, necessarily, any compulsion on the actor to take the action, the compulsion relates only to the interpretation of evidence,
usually by the commentator. Examples are:

She had to have been to the hospital because her leg was in a plaster cast
She had to have been to Glastonbury, she was still wearing a festival wristband
She had to have been to Versace's, she was carrying bags from there.
She had to have been to Los Angeles, her suitcases had LAX baggage tags on them
Answer: "She had to go there" = it was necessary for her to go there.
"She had to have gone there" = it was obvious (to someone else) that she must have gone there.


Cannot Add User on KDE Neon User Edition Live

Question: I've been learning Linux with Ubuntu 18.04 but recently I wanted to try out a different desktop environment compared to GNOME. So I decided to run a Live version of KDE Neon 5.16.0( released 13 June 2019 ). After playing around with the panels and pre-installed applications I wanted to create a user account for myself with administrator privileges. But it seems that I can't escape being a Live session user. User Manager doesn't seem to save my new user details after I click Apply. I also tried rebooting Neon just to see if that would work but to no avail. It would be nice to have a static user account so I can save my progress, because every reboot seems to just be a refreshed Live session user account. Apologies if I'm missing something obvious to KDE environments.
Comment: This happens because it is a live system which is not persistent - meaning any changes you make will only happen in memory and be gone after a reboot.
Comment: @Panki Ah ok I thought as much since live is usually just to test out the OS. I was using Bodhi live before this as well and assumed my setting changes were saved but never checked thereafter. Thanks alot.
Comment: Instead of using Live USBs or whatever, why not do an install as a virtual machine? Depending on your machine's specs, you may not get all of the fancy desktop effects, but otherwise VMs are a nice way to learn.
Comment: @DK Bose I definitely am going to set that up on my home system in time, and with the specs my current machine runs I think it'll do justice with each distro. But I just wanted to try some of the distros out on flash drives since I could just carry them around with my laptop for now. So to solve the volatile memory and refreshed profile that happens every time, I came across mkusb to create 'persistent' live versions, and did this with KDE Neon 5.16.0. Now I can save my changes. It's the best option really that I've came across so far when it comes to a real portable experience.
Answer: Following commentary above, indeed because of it being a Live usb the changes made to it will not be saved when it's shut down and not powered. As such the Live edition will also not be able to create new accounts because it is limited to Live User Session profiles for testing purposes.


Tracks in a GPS file format

Question: How to fill a file with different GPS tracks so that when opened in a GPS track viewer the tracks appear simultaneuosly as different tracks? What GPS viewers do that?
Answer: EasyGPS will do that for you. You can add separate tracks to a new .gpx file and label them - make sure both the 'Label' and the 'Name on GPS' fields are filled out. Save the result and load it onto your unit.

Tracks in a GPS file format


Four elements repetition in a texture

Question: I have to create a texture using 4 different elements (call them A,B,C,D or whatever you want) on a 6x7 grid. The goal is to obtain a pattern with the least repetitions of the same element in horizontal, vertical and diagonal directions, especially, if possible, should be avoided to repeat the same element in adjacent blocks. I think there should be different solution to this, just answer with what you came up with.
Comment: I'm not clear on what you're counting as a repetition.
Comment: I know this question sounds simple but is varies alot based on priority.  Is A and A being diagonally adjacent worse than horizontally adjacent?  Is A and A being diagonally adjacent worse than it having three As separate but in the same row?
Answer: Here is one:
$$a b c d a b\\
b c d a b c\\
c d a b c d\\
d a b c d a\\
a b c d a b\\
b c d a b c\\
c d a b a d\\$$
In the row you must have 2 repetitions and in the column 3.
Comment: If you look in diagonal, there is the same letter in each oblique line (going from lower left to upper right)
Comment: You are right! I missed diagonally.
Answer: Starting from the nucleus
$$a b a\\
b c b\\
a b a\\$$
add "layers" of two characters alternating onto the nucleus. For example, the next iteration will be
$$c d c d c\\
d a b a d\\
c b c b c\\
d a b a d\\
c d c d c\\$$
This array can be extended infinitely, and all elements of this infinite array will have neighbours in all 8 directions that are different from itself, except at the corners.
$$c d c d c d\\
a b a b a b\\
c d c d c d\\
a b a b a b\\
c d c d c d\\
a b a b a b\\
c d c d c d\\$$
Simply take a 6x7 subset of this infinite array at any position where no corner exists to produce an answer.

Four elements repetition in a texture


How can I know that I know something?

Question: This also a question about what is the definition of knowledge.
Comment: @AlexanderSKing see Keelan's comment; way too broad without some narrowing context.
Comment: If you're asking for a definition, this question is off topic per the [help]. Please specify which definition of knowledge you're using, and what research you have done on this topic already.
Comment: Why the down vote? this is a valid question in epistemology.
Comment: possible duplicate of [Do we know whether we know something?](http://philosophy.stackexchange.com/questions/2868/do-we-know-whether-we-know-something)
Comment: On second thought, probably not duplicate; though related.
Comment: I'm now voting to close this question as off topic as it's asking for a definition and you did not make an attempt to make the question a better fit for this site.
Comment: I don't understand the purpose of this site if everyone is voting to close discussions instead of discussing
Comment: @SharonSalmon - it's not a discussion site. It's a StackExchange (see http://en.wikipedia.org/wiki/Stack_Exchange). So it's suited to questions that mirror certain types of programming and technical questions. That means we can answers certain types of questions but not all, and it is not well-suited to open-ended discussions...
Answer: A well known definition of knowledge is the Justified True Belief (JTB) account.
For me to know x, the following necessary conditions must hold:

x is true
I believe that x
I am justified in believing that x

These conditions are individually necessary and jointly sufficient.
However, the JTB account of knowledge can fall prey to the Gettier problem. Here is the classical formulation of the problem:

Smith and Jones have applied for a particular job. Smith has been told
  by the company president that Jones will win the job. Smith combines
  this with his observation that there are 10 coins in Jones' pocket. He
  then infers that whoever gets the job, will have 10 coins in their
  pocket. Smith's belief does have a fair amount of justification. He
  was told by the company president that Jones will win the job & he
  observed that Jones has 10 coins in his pocket.
However, it turns out that Smith ends up winning the job. He also had
  10 coins in his pocket yet he was unaware of this.
Smith's belief was that the winner would have 10 coins in his pocket,
  this is true. Smith therefore held a true belief. However, Smith did
  not know that he had 10 coins in his pocket. As a result of this new
  information, can we really say that Smith has a JTB?

Just to highlight that there is more than one approach to knowledge, take a look at the following.
I know x if and only if:

x is true
I believe that x
Belief in x is the result of a reliable process

This is a broad picture of an approach to knowledge known as reliabilism. It is concerned with the truth-conduciveness of your belief forming method.
See http://plato.stanford.edu/entries/epistemology/#STR for further information.
Comment: I don't understand why believing the one that will get the job will have 10 coins is considered true believe ? It can be one of many beliefs and it is just speculation.the winher can have any amount of coins for many reasons.I think Plato should have listen to his teacher Socrates and accept there is ni such thing as knowledge,its an illusion
Answer: I think knowledge is a term that is only relevant to mathematical truths where we are the creators of the rules and the axioms.
Then we can claim knowledge of things in the scope of this created world.
But we cannot do this on our real world because there are no axioms in the real world, only assumptions.
Although it is very hard to accept, we don't really know if tomorrow the sun will shine.
We only have very strong belief it will, because we have very strong belief in science, but it is just belief and not knowledge.
I truly believe that getting used to this can make people much happier just by itself, because it gives a better perspective about the notion of just.
Answer: This isn't a question with a single, universally endorsed answer, but one with a long history of debate.  The field that encompasses study of knowledge is called Epistemology.
One of the most foundational definitions of knowledge, credited to Plato, is that knowledge is "justified, true belief," meaning that you believe something AND the something you believe is true AND you have a good reason for believing it.  If you accept this, then you know you know something when you have a justified true belief that you have a justified true belief about something.
This definition has often been challenged, however, see the above link for more info.
Comment: @SharonSalmon You could write a whole book, and not even begin to scratch the surface on the debate over answers to that question...  You might have better luck if you asked what a specific philosopher said about that question.  Otherwise you're just directly tackling one of the central ongoing debates in all philosophy.
Comment: How can someone tell objectively that something he believes in is "true" ?
Comment: @SharonSalmon - in order for something to be considered objective it should be repeatable, ie, others can repeat your steps and get the same result. Quantitative measurements are objective. (Posted to wrong place last time). If you want to know if what you know is true, ask others to help test it with you.
Answer: At some point, I believe we should just accept the way we comprehend the world, take it as an axiom, without questioning it. The goal is to find that border that is generally accepted by all of us - you can always continue asking more 'but why' questions with regard to any topic, but we generally assume it's reasonable to stop at some point. Otherwise, you would spend your life on asking such questions which isn't a very efficient way of life.
Comment: Sorry but I don't agree with that.I can live perfectly and efficiently by accepting that all I can have is beliefs and not knowledge.
Comment: Yes, I agree with what you've said. It agrees with what I've written though. My point is that the process of asking 'why' questions will never end, so at some point you need to accept the statements you're questioning as true.
Comment: So if I say the sun will shone every morning and others repeat my test and see it true,is it true forever ?
Comment: Of course not - there's a a very little chance that the sun will not shine the next morning - but it's possible.
Comment: You don't know if the chance is big or small ,you can only assume (i.e. believe) the chance is very small. Saying anything about what will happen tomorrow is future telling and no one can do that.unless god himself came to you and told you that the world obbay the laws of chance and not random,there is no way you "know" what are the chances fo the sun to shine tomorrow

How can I know that I know something?


Connecting to a SonicWall VPN from a Linux machine

Question: Is there a SonicWall client for Linux? When I searched around I could only find answers several years old.
Comment: I found a knowledge base page on their site that explains how to install the VPN client for linux. https://support.software.dell.com/kb/sw5918. Not sure if this can help.
Answer: The download link for the Linux client from SonicWall is here.
Go to that page, the follow the directions to log in to the Beta site as a guest (username is "demo", password is "password" - as provided on the page), then click the large NetExtender button, which will initiate a download of the latest .tgz file.
Extract it and run ./install as root (using sudo), then run the GUI. The installer has instructions to help you all along the way.
Comment: @JoãoAbrantes do not ask questions in the comments. If you cannot find the answer in another question, then use the Ask Question button at the top of the page to ask your own question and get your own answers.
Answer: As it was remarked that most links in the existing answers were dead and
not much information was available,
I thought to list below some resources that still exist:
The NetExtender clients (and others) can be downloaded from the
Clients Download page
and installation notes are available in this
Knowledge Base article. Here are the links from the above page:

Linux 32-bits
Linux 64-bits
Windows .exe

Some more useful articles :

Ubuntu Linux: How to setup a VPN connection to a SonicWall router using Openswan and Pre-shared Keys (PSK) (from 2009)
How to Install Dell's SSL VPN client – NetExtender – on Ubuntu 16.04.x (from 2016)
SonicWALL VPN with FreeS/WAN using IKE (old one from 2002)
Comment: Thank you! NetExtender works for me. It's closed source, it has ugly Java GUI, it causes tons of SELinux warnings, but it gets the job done. The open source solutions ask for ID and shared secret, and I don't have them. NetExtender doesn't even ask for them. The ID is probably GroupVPN, but the shared secret eludes me.
Answer: There is no special client for SonicWall. Use Openswan on your linux box, configure a tunnel between your box and sonicwall, with NAT traversal.  Here are few docs:
http://www.vpn-technology.com/Interoperability/SonicWALL%20VPN%20with%20Red%20Hat%20Linux.pdf
http://www.sonicwall.com/us/support/2134_8175.html
http://archives.free.net.ph/message/20070322.043752.86474680.en.html
Edit: follow the comments for better answer
Comment: All three URLs are now dead links.
Comment: That's no longer true, FYI, there is now a Sonicwall connection utility for Linux
Comment: NetExtender is the Sonicwall VPN client for desktops (as opposed to an always-on connection, to a satelite office for example).  The client does have Linux builds available and works fairly well.  If you have the SonicWall Virtual Office enabled on your appliance then you can download the client by going to `https://your-sonicwall-public-ip:4433` and logging in with a regular (not "admin") user account. I'm not certain those details are all stock settings, but we've used them a few times on a TZ205 appliance with ~5.8.0+ firmware.
Comment: @JustinBuser Details?
Comment: ps) the latest version of NetExtender can also be downloaded after logging in to `http://mysonicwall.com` - again YMMV depending on what you own and have registered to your account
Answer: I'm not sure if this is model specific but where I work we have an Aventail WorkPlace SonicWall VPN. When you put the hostname that you use to connect to it into a browser it takes you to a page that has links where you can download client software to connect to the VPN box. From here there are links to down Linux VPN client software.
The software comes in 32/64 bit formats as tarballs named, AventailConnect-Linux.tar & AventailConnect-Linux64.tar.
The only other branding that I've noticed on the download page is that it says nortel in the title page, and "Aventail Connect with smarttunneling", on the side of the download page.
I wrote up on my blog about this as well, http://www.lamolabs.org/blog/4720/setting-up-aventail-vpn-software-on-linux-fedoracentosrhel/. I included some screenshots in that post of the various pages where you can download the Aventail VPN client software.
Answer: If you have a My Sonicwall account, you can download SSL VPN clients for Linux. The Program is called NetExtender.
Answer: Note that NetExtender is a gui app intended to run from a desktop session. If you want something that'll run at system level, you'll have to go for OpenSwan or similar.
Answer: Download netextender from sonic wall. Add the suffix :4433 to the IP address and specify the domain as LocalDomain. This worked for me.
Answer: In case it is still useful.
Where I work Connect Tunnel is used, try the connection with NetExtender without success, thanks to this answer browse the demos until you find a link where the installer that was mentioned in other pages "ConnectTunnel-Linux64.tar" is downloaded https://access.sma-demo.com/workplace/access/home there will download a .jar, unzip and follow the steps https://www.dundee.ac.uk/guides/vpn-linux.
translated by Google
Por si aun es util.
en donde trabajo se usa "Connect Tunnel", intente la conexión con "NetExtender" sin éxito, gracias a esta respuesta navegue por los demos hasta encontrar un link donde se descarga el instalador que se mencionaban en otras paginas "ConnectTunnel-Linux64.tar" https://access.sma-demo.com/workplace/access/home alli descargaran un .jar, se descomprime y se siguen los pasos https://www.dundee.ac.uk/guides/vpn-linux.


Is accretion disc caused by frame dragging?

Question: Is accretion disc around a Kerr black hole the result of its frame dragging?
Comment: Plain Newtonian mechanics predicts an accretion disk, so I don't think you could reasonably say frame dragging is the cause. I assume it influences the state of the disk in some way, though.
Answer: No, you get accretion disks around other bodies too, like stars during planetary system formation and especially in binaries when the companion star overflows the Roche lobe. They become particularly noticeable for dense objects, though.
The reason for an accretion disk is that gas and dust orbiting something will not spiral inward unless there is some dissipative interaction that allows it to shed energy and angular momentum. If we consider a random cloud around a dense object, interactions between constituent particles can make one particle go into a closer orbit while the other goes into a higher orbit (carrying off some angular momentum), plus release some energy that is radiated away. Conservation of overall angular momentum will also flatten the cloud into a disk orthogonal to the angular momentum vector as it self-interacts and loses energy. The result is an accretion disk where turbulence, friction, particle interactions and sometimes electromagnetic effects serve to dissipate energy that is radiated away. As mass spirals inwards potential energy becomes kinetic energy, and for dense objects the high velocities produce noticeable radiation.
Frame dragging matters only very close to a black hole. A more important limit is the innermost stable circular orbit (ISCO): as the disk matter passes it, the matter will plunge inward. This is the inner edge of the disk. One could image a counter-rotating disk where frame dragging makes the ISCO further out, but it is expected that the disk and the hole typically rotates in the same direction.
Answer: Accretion disk is not caused by frame dragging. Accretion disk is formed due to the gravitational attraction of matter surrounding a black hole. In general, black hole accretion is a transonic process. On the other hand, frame dragging is caused only around rotating black holes described by the Kerr metric.
For reference, you can look at the following papers:
Transonic Accretion and Winds Around Pseudo-Kerr Black Holes And Comparison with General Relativistic Solutions
Constraints on Transonic Black Hole Accretion
Rotating accretion flows: From Infinity to the Black Hole
Horizon-penetrating Transonic Accretion Discs Around Rotating Black Holes


red velvet cake - cake flour?

Question: I am looking to bake a red velvet cake, but I've seen different recipes, some use all purpose flour and some use cake flour. There are some diy cake flour recipes too since I don't have cake flour. I'm wondering what's the difference if I use all purpose flour instead of cake flour? Will it make a difference? I'm undecided on which recipe to use too so if you also have a suggestion that would be great, thanks
Answer: Cake flour is milled more finely than all purpose flour.  It also has a lower protein content, so less gluten is produced in the final product.  It is ideal for achieving the soft crumb of a cake.  That said, plenty of cakes are made with all purpose flour.  You would be able to perceive a difference in a side-by-side comparison.  In your own kitchen, with one cake, it is not going to matter too much.  I would suggest you sift your dry ingredients and move ahead with AP flour.  It will not be a problem.
Answer: even if you have to use the substitute (APF + cornstarch), try it so you will know for yourself what the difference is. all i can tell you is that it creates a lighter, softer and more delicate crumb. many people like cakes better with this type of crumb.
Comment: Yeah I think I'm going to try that. I was just wondering if it was going to really affect the cake in a bad way if I just used AP flour. thanks!
Comment: sure :-) so did you try using it? how did it turn out?

red velvet cake - cake flour?


Would a white hole have an event horizon?

Question: I know, thee are no white holes. My question is not about their existence. I am asking about the mathematics of the white hole solution. Does it produce an event horizon or is it a naked singularity? What would be the physical meaning of such an event horizon? Hypothetically, if a white hole existed, what would it look like?
Comment: @Countto10 I agree with the time reversal analogy, but this symmetry seems broken. Consider various objects fall into a BH randomly over time. Sometimes a dust, sometimes an asteroid or even a nearby star gets sucked in. Then, how do we reverse this in time? Would a WH spit out random objects like a spaceship with live astronauts? Created in the singularity and speaking fluent English? :) I guess not, it would have to be some symmetrical and steady radiation (or nothing). Or, say, nothing falls to a BH. So, time reversal, nothing comes out of WH? Then what is the difference between them?
Answer: Here's a Penrose diagram for a white hole:

It's just an upside-down version of the diagram for a black hole. There is a horizon, but the interpretation of the horizon is reversed compared to that of a black hole. The horizon defines an area that no null or timelike curve from past null infinity can enter.

Would a WH spit out random objects like a spaceship with live astronauts?

Yes.
As in a black hole, the singularity is a spacelike boundary. However, the white hole's singularity is a spacelike boundary that lies in the past of all observers, similar to the big bang singularity. Just as we have no physical laws that can predict what pops out of the big bang singularity, we have none that could predict what would pop out of a white hole singularity. The basic problem is that to make predictions, we need a Cauchy surface, but we don't have a Cauchy surface that lies earlier in time than these past singularities.

is it a naked singularity?

There are varying definitions of a naked singularity. Most are cooked up in such a way that the big bang singularity is not a naked singularity, and the same would apply to a white hole singularity. For example, one can define a naked singularity as one that can lie in both the future and past light cones of the same observer. By that criterion, this is not a naked singularity.
One of the things that is disturbing about naked singularities is that they break causality by making Cauchy surfaces not exist at all. A big bang or white hole singularity is much less threatening, because it doesn't have this property.
Comment: I don't think anyone denies that the big bang is a naked singularity. Since there is a horizon of the white hole, I don't think it can be thought of as a naked singularity at all. A naked singularity simply admits no horizon. There are various formulations of the censorship conjecture, all formed in a way that no naked singularities other than big bang can be allowed. These varied formulations might add some variability to the precise def of naked singularity but whether the big bang or a white hole is a naked singularity or not is not disputed as far as I know. Correct me if I'm mistaken.
Comment: @Dvij Your reasoning for why the white hole is not a naked singularity applies to the big bang as well. Nothing we can transmit now can reach the big bang. There is a causal horizon between you and your past. So your "a naked singularity admits no horizon" is just like BenCrowell's "one can define a naked singularity as one that can lie in both the future and past light cones of the same observer".
Comment: @PPenguin "Nothing we can transmit now can reach the big bang." I think this argument is irrelevant. Nothing you can transmit now would reach the event of your birth either. But that doesn't mean there is a horizon between you and your birth. The spacetime has been pretty flat between those two events. There is a geodesic, timelike at each point, that connects me to the big bang. This **proves** that there is no horizon between me and the big bang.
Comment: On the other hand, there can't be any such geodesic between me and a white hole singularity. Making it clear that it admits a horizon.
Comment: @Dvij There are event horizons all over flat space-time. This is what gives space-time its causal structure. If you look at Rindler coordinates you can even make the horizon look like a fixed barrier similar to hovering outside of a blackhole horizon.
Comment: A singularity is "naked" if information from it can reach you and information from you can reach it.
Comment: Let us [continue this discussion in chat](http://chat.stackexchange.com/rooms/66788/discussion-between-dvij-and-ppenguin).
Answer: Consider the full Penrose diagram for the Schwarzschild metric below. The region I and II are timelike regions similar to the observable universe. The two lines at $45$ degrees are event horizons at $r~=~2m$ The region III is the interior of the black hole and the region IV is the region interior to the white hole. The horizontal lines are the spacelike singularity. Geodesic proceed from the bottom to the top. We may think of particles or fields created by the bottom singularity and absorbed into the top singularity. This is a diagram which represents the solution in a conformal map.
Ordinarily the white hole is ignored. There were speculations back in the 1960s and 70s that black holes resulted in an out gushing of material, but this was largely abandoned. The reasoning being that material falling onto a black hole is accessible in principle by the outside observer. Oscillation modes of matter appear slowed and outgoing photons from matter just above the horizon red shifted by the tortoise coordinate. If this material then erupts elsewhere this seemed to be a violation of mass-energy conservation.
However, if you think about it Hawking radiation involves ingoing modes and outgoing modes of radiation. A black hole over time loses mass and radiates more rapidly and further in the UV as its temperature $T~\simeq~1/8\pi m~$  increases. A black hole transitions into being more of a white hole. Towards the end the black hole is very hot, bright and explodes. So we might say that in a sense white holes might exist. They come from black holes; we just have to wait around long enough. The Penrose diagram then has some quantum implications.
Comment: I appreciate the visualization, but I'm wondering about one of your analogies, which is that a white hole emitting Hawking radiation ends that emission while remaining "very hot and bright":  In his 2010 book "Cycles of Time", which many readers have found obscure, Roger Penrose  (who was sometimes a collaborator of Hawking in other works) claimed that any BH of stellar origin would end its existence with a "pop" only comparable to a medium-range artillery shell!  Is some BH/WH transition or spatial scale factor (such as the WH being smaller overall) involved in your version, or maybe in his?
Comment: The end point of black hole quantum radiance is not maybe well understood. However, the black hole would in its last million metric tons evaporate in a matter of seconds, and this mass converted to UV radiation. That would be quite a large explosion, though at a distance it would amount to only a tiny flash. It would be very difficult to detect at any distance outside the Milky Way. So far no such flash has been detected. The connection to the conformal diagram is just formal. It does indicate how spacetime has some quantum features, but is purely formal.
Comment: In addition I fixed a small mistake the text above.
Answer: White holes probably don't exist, but they are possible because allowed by solutions of the Einstein equations for General Relativity (GR). There's been lots of speculation and science fiction about them, but the causal aspects are pretty well described by Penrose diagrams, such as those shown by the Crowells postings.
Whether you define those white hole singularities as naked or not it is clear that the white hole can have energy or information come out to the future. Does not mean a white hole exists, just that it is permitted by GR. It may or may not be possible to have one form.
White holes have been more talked about in the context of what is called an Einstein-Rosen bridge. It is a solution of GR that can be mathematically constructed that has a Black Hole on one side and a White Hole on the other, joined by the bridge. They have never been seen or detected, so it is mostly speculation, but again under some conditions they are permitted by the theory.
See Penrose diagrams at https://en.m.wikipedia.org/wiki/Penrose_diagram where you can see both Black and White Holes and also wormholes
See wormholes at https://en.m.wikipedia.org/wiki/Wormhole#Schwarzschild_wormholes
The thing about wormhole solutions is that it was shown early on that the bridge between White and Black Holes (or most of them but with the bridge instead of singularities) are not stable, and collapse faster than light can traverse them. That was shown by Wheeler, but it was later shown that if one allows the bridge to include 'exotic' matter (essentially never observed negative energy matter) that the bridge could be stable for long enough that energy and information can go from the Black Hole region to the White Hole region, and escape through its past horizon into a spacetime (sometimes called a universe, but it doesn't mean the two outside regions can not be otherwise connected also).
So the questions:
1) can a White Hole have an event horizon? Clearly yes, it allows travel one way, from inside the White Hole to outside it. Wormholes allows, possibly, a path from a nearly Black Hhole to another spacetime through an almost White Hole.
2) could it spit out random objects? For White Holes it'll spit out whatever comes out of the past singularity, and there is no way of predicting what it is. For wormholes it'll be some form of what goes in into the Black Hole side. Causality doesn't seem to be violated, there are no singularities.
3) can that cause a-causal behavior? White holes could, but wormholes seems would be causal.
4) doesn't the pure White Hole violate causality in such a way that it would propagate through the future spacetime, and thus not be 'safe', in the same way that naked singularities are hypothesized not to exist? Seems that way.
The unanswered questions or issues means that classical GR or even quantum fields in a GR background is an incomplete theory, and we need Quantum Gravity to get to what's inside a Black Hole and what is it that exists in those cases that GR describes as singularities.


Tips for reading ASM code?

Question: I have an exam coming up on HC12 Motorola assembly code. Any tips to improve my time in read and understanding asm code efficiently and accurately?
My problems:
I take a long time to read asm code accurately and if I rush my stack is messed up!
Answer: ASM code is hard to read. There is no magic thing that makes it easier to decypher.
The only tips I can give you: Add lot of comments to the code. Document what a sequence of instructions does. Don't focus on the instructions itself unless you have to.
Also assembler reading skills can be practiced fast. If you spend some evenings writing little toy programs you'll be able to understand other peoples code with ease. You will develop the skill to focus on the important things, so you have less code to read overall.
Answer: This blog post is kind of related. It's a series of visualizations of Atari 2600 games, their machine code and data segments, illustrated with lines denoting jumps.
It's not an answer, but it's interesting.
Answer: I remember my institute. I printed difficult assembler program on a paper roll and then I covered this role with color lines (by pencils), designating procedures, blocks, jumping and other things. Maybe there exist some programs for "visualisation" of Motorola assembly code, but I don't know about it.
Comment: good point! Back in the days when I was at the university I've used the time in the public transportation (two hours a day) to read and debug my own asm-code.
Comment: Please, don't use toilet paper roll! :)))
Answer: Since this is an exam, handle it like any other exam - organize! You need to be able to quickly identify code blocks. Start with the branch/return instructions that break the control flow. These typically indicated a loop or mark subroutines. Once you have and idea of how the code flows, then figure out what it does within each block.

Tips for reading ASM code?


Why didn't Jack Harmon simply enter the embassy basement by himself?

Question: Mission: Impossible (1996) established that the crew could simply open/close elevator doors at whatever floor of the building, and Jack already had access to the elevator shaft. So why didn't Jack Harmon (Emilio Estevez) simply enter the embassy basement by himself? The whole scheme they devised was unnecessarily complex.
Answer: TLDR: Jack needed access to the circuity of the elevator to be able to upload Sarah's thumbprint and ID picture into the embassy's security system.
From the script:

JACK, wearing black coveralls and slightly odd-looking
       eyeglasses (they're called Visco glasses), enters an elevator
       shaft through a small door at the base of the wall.  He looks
       up the shaft, shining a flashlight until he finds what he's
       looking for --
a gray metal box, protruding from the wall one floor up.

The party progresses a little bit more, and then the script states:

JACK climbs up the elevator shaft, towards the gray metal
       box.  He just begins to remove the cover when he hears a
       noise from above.  He looks up and sees the elevator above
       him descending.
JACK quickly pulls himself flush against the wall. The
       elevator comes down adjacent to him and stops, pinning him
       to the wall.
JACK
                  Great.  Come on.

Finally, a little later, the script states:

JACK is still pinned to the wall by the elevator, listening
       to their conversation.
PHELPS (O.S.)
                  Jack's pinned down Sarah.  Should be a
                  second.  Keep dancing.
ETHAN (O.S.)
                       (with the Senator's southern accent)
                  We were forced to tie him to my best
                  stallion and drag him around the barn a
                  few times.
Finally, the elevator moves down a floor and JACK is freed.
JACK
                  Relax your crack, Foghorn, I'm workin' on
                  it.
He quickly opens the gray metal box, revealing a maze of
       circuitry.  He patches in his computer, climbs on top of the
       elevator, and hits the keyboard, beginning to download.
There's a split-screen of SARAH's thumbprint and the ID
       picture.  JACK downloads her file into the security computer.
Ignoring the GUARD, SARAH turns and slides her thumb into the
       thumbprint analyzer once more.  The panel glows, this time
       the message flashes --
<code>IDENTITY CONFIRMED
</code>
and the elevator doors slide open briskly.

So it wasn't just a case of opening and closing the elevator doors, but of ensuring Sarah could access the secure room by having her credentials uploaded to the embassy's security system.
Edit:
When the team are being brief, it is mentioned their objective is to photograph Golitsyn stealing the NOC list and apprehend him to his buyer.
Sarah and Ethan access the computer room where Golitsyn views the NOC list. In that room, Ethan leaves a pair of glasses which are used to spy on Golitsyn to discover the password he us using to access the NOC list. The only way they can discover that password is by physically going to the room and leaving the camera - and the implication through what we are told is this is only doable via entering the elevator and passing the embassy security staff.
We do see that Jim can open and close the elevator doors, so I understand the query about why not just enter the shaft, like Jack did, access the room and get out. However, the embassy could have security systems in place, such as CCTV, to enable them to easily detect intruders in the computer room. Instead, it was deemed safer to gain admittance via disguise.
I'll fully admit, my interpretation is pure conjecture (and the film is deliberately obscure in its opening film to create a sense of mystery and intrigue).
Comment: But why would Sarah need access to the secure room? It's established that Jon Voigt's character can remotely open the elevator doors whenever he pleases. So I wonder if Jack couldn't have simply snuck in by himself (unless, of course, the only way they could manipulate the elevator was after someone's credentials had been verified by security)
Comment: @PederRice: Hi Peder. I've added some more comments, although I fully admit it is conjecture.


Cannot edit layers in PSD after exporting from Illustrator

Question: I have exported .ai layers into PSD and now I cannot edit colours of the layers or select the individual layers on the image. I can select the layer in layer panel but it does not highlight the layer object or able to change colour.
Answer: Correct, when you import an .ai file into Photoshop it is as one Shape Layer. To make edits to the original .ai you need to do so in Illustrator.
Depending on what you're doing there might be a better workflow such as using InDesign for the final layout and linking the vector files and raster files.
Comment: Thanks Ryan. I want to edit each layer in photoshop because it has more options for creating colour overlays and blend modes etc. I have successfully exported all layers (each one inside a folder!). If I copied and pasted from illustrator one by one I can do all the edits. I have 200 layers so I cannot really do this one by one..


Altium database library management - Is it possible to edit same database lib by two people?

Question: We are using Altium database library. But our concern is if an engineer is working on the library then another engineer who needs to add new part in the same database have to wait. Is there a way to add the component in the same library by two or more persons at a time?
Answer: You don't edit the .dblib file, you edit the data in the database. As long as the users refresh the database after each change, you should be fine. Even if you don't, Altium refreshes it by itself, usually on start up. Also, schematic components that were already placed get updated.


Proving Quadratic Formula

Question: purplemath.com explains the quadratic formula. I don't understand the third row in the "Derive the Quadratic Formula by solving $ax^2 + bx + c = 0$." section. How does $\dfrac{b}{2a}$ become $\dfrac{b^2}{4a^2}$?
Comment: It's not becoming, it's identifying the square of the co-efficient of 2x to be added to either side, to make the LHS a perfect square.
Comment: If you want a very intuitive, easy-to-understand derivation of the quadratic formula, you might want to check out [this answer](http://math.stackexchange.com/a/49243/32374)!
Comment: @Mouse Hello please tell me is there some wrong procedure in my answer?i am sure you have not downvoted,just because you have asked this question,i need you answer,you opinion
Comment: Sorry if I missed any comments, I haven't accessed this site for 2 days haha
Comment: @dato Sorry if I missed your answer, I can't seem to find it
Answer: $b/2a$ does NOT become $b^2/4a^2$.  All that happens in the third row is that $b^2/4a^2$ is added to both sides of the equation.
The bit about taking half of the $x$ term and squaring it is just a means of working out WHAT to add.  This is often called "completing the square" - adding a constant term to an expression to turn it into a perfect square, so that one may later take its square root.
Answer: Remember how to complete the square:
$$Ax^2+Bx=A\left(x+\frac{B}{2A}\right)^2-\frac{B^2}{4A^2}$$
So now
$$ax^2+bx+c=0 ---- \text{complete square}$$
$$a\left(x+\frac{b}{2a}\right)^2-\frac{b^2}{4a}=-c$$
$$\left(x+\frac{b}{2a}\right)^2=\frac{b^2-4ac}{4a^2}$$
$$x_{1,2}+\frac{b}{2a}=\pm\frac{\sqrt{b^2-4ac}}{2a}$$
$$x_{1,2}=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$
Comment: good answer @DonAntonio
Answer: $$ax^2+bx+c=0 - \text{divide by $a$ because $a\neq 0$ }$$ we get
$$x^2+\frac{b}{a}x+\frac{c}{a}=0$$
$$x^2+2x\frac{b}{2a}+\frac{c}{a}=0$$
$$x^2+2x\frac{b}{2a}+\frac{b^2}{4a^2}-\frac{b^2}{4a^2}+\frac{c}{a}=0$$
$$x^2+2x\frac{b}{2a}+\frac{b^2}{4a^2}=\frac{b^2}{4a^2}-\frac{c}{a}$$
$$x^2+2x\frac{b}{2a}+\frac{b^2}{4a^2}=\frac{b^2-4ac}{4a^2}$$
$$x^2+2x\frac{b}{2a}+\left(\frac{b}{2a}\right)^2=\frac{b^2-4ac}{4a^2}$$
if in LHS we use $x=A$ and $\frac{b}{2a}=B$ then we have
$$A^2+2AB+B^2=(A+B)^2$$ or
$$\left(x+\frac{b}{2a}\right)^2=\frac{b^2-4ac}{4a^2}$$
we have two values of square roote
$$x_1+\frac{b}{2a}=+\sqrt{\frac{b^2-4ac}{4a^2}}$$and
$$x_2+\frac{b}{2a}=-\sqrt{\frac{b^2-4ac}{4a^2}}$$ or
$$x_{1,2}=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$
Comment: Very nice Adi. Free Kosovo
Answer: See my videos,  completing the square, part I  and  part II .
Answer: \begin{align*}
ax^2+bx+c &= 0 \\
ax^2+bx &= -c \\
x^2+\frac{b}{a}x &= -\frac{c}{a} \\
x^2+2x\Bigl(\frac{b}{2a}\Bigr)+\Bigl(\frac{b}{2a}\Bigr)^2-\Bigl(\frac{b}{2a}\Bigr)^2 &= -\frac{c}{a} \\
\Bigl(x+\frac{b}{2a}\Bigr)^2-\frac{b^2}{4a^2} &= -\frac{c}{a} \\
\Bigl(x+\frac{b}{2a}\Bigr)^2 &= \frac{b^2-4ac}{4a^2} \\
x+\frac{b}{2a} &= \frac{\pm\sqrt{b^2-4ac}}{2a} \\
x &= \frac{-b\pm\sqrt{b^2-4ac}}{2a}
\end{align*}
Answer: From Maths is Fun.

Hope this helps
Answer: I see no visual proof, so I will add one.
The rectangle below is broken up into to parts: a square and another rectangle. Note that the area of the original rectangle is given by the sum of the two smaller areas: $$x^2 + bx$$

The next step is to divide the smaller vertical rectangle by two, rotate the strip and add it to the bottom:

The new figure is a square with sides $x + \frac{b}{2}$ and a bite out of the bottom right. The bite is also a square, and has sides $\frac{b}{2}$. The area of this figure, then, is the area of the square, less the area of the bite:
$$(x + \frac{b}{2})^2 - (\frac{b}{2})^2$$
But this "square less a bite" figure must have the same area as the original figure, since it was obtained by cutting the original figure and rearranging the pieces. So we can equate the expressions for both these areas:
$$x^2 + bx = (x + \frac{b}{2})^2 - (\frac{b}{2})^2$$
At this point, you can satisfy yourself of the above equality by multiplying out the business on the right, simplifying, and showing that it becomes the expression on the left.
Now you have a way of rewriting quadratics of the form $x^2 + bx$ which will prove to be very useful very soon.
When we're looking for the roots of a quadratic equation, we are looking for the values of $x$ that make it zero. The equation will take on this form: $$Ax^2 + Bx + C=0$$ so let's make it look like $x^2 + bx$. First, divide everything by $a$:
$$x^2 + \frac{B}{A}x + \frac{C}{A} = 0$$
In the previous equations, the coefficent of $x$ was $b$. In this new equation, it's $\frac{B}{A}$. Let's rewrite the above equations, substituting
$\frac{B}{A}$ for $b$, and adding in $\frac{C}{A}$ to each side, so it all equals zero:
$$x^2 + \frac{B}{A}x +\frac{C}{A}= (x + \frac{B}{2A})^2 - (\frac{B}{2A})^2 +\frac{C}{A}=0$$
Rearrange a bit and begin to solve for $x$:
$$(x + \frac{B}{2A})^2 = (\frac{B}{2A})^2 -\frac{C}{A}= (\frac{B}{2A})^2 -\frac{4AC}{4A^2}=\frac{B^2-4AC}{4A^2}$$
Take the square root of both sides:
$$x + \frac{B}{2A} =\pm\frac{\sqrt{B^2-4AC}}{2A}$$
And, finally, bring $\frac{B}{2A}$ to the right:
$$x =\frac{-B\pm\sqrt{B^2-4AC}}{2A}$$

Proving Quadratic Formula


Online Torah Scroll

Question: Is there an online virtual Sefer Torah (in 3D) that could be rolled and unrolled?
Comment: Here is a complete open source online scan of a Torah scroll https://commons.wikimedia.org/wiki/File:Sefer-Torah-Elihu-Shannon-2.djvu
Comment: Obviously it wouldn't have the sanctity of a real Torah scroll. Are you asking if anyone has put up some sort of animation? What would be the advantages?
Comment: This post contains two questions: 1) Does this product exist, and 2) Would it be halachically problematic. These are two very different kinds of questions, and I think they should be addressed in separate posts. Therefore, I would encourage you to [edit] the second question out of this post, post it as a separate question post, and when you do so, clarify what kinds of halachic issues you think may apply (e.g. permissibility of creating such a product, suitability of such a product for use in a synagogue service, permissibility of casual use, conditions of use, etc.)
Comment: Yes, that's what I'm asking. It would just be an interesting thing, that's all. They have VR versions of everything so I thought maybe someone might had made as you said, a nice animation of a Torah scroll.
Comment: Did anyone ever find a VR Torah scroll?
Answer: By definition a Torah scroll used in synagogue must be made of parchment. An online version would just be images, no different from any other online file.
From Maimonides:

It is a rule dating back to Moses who received it on Sinai that the scroll of the Law should be written on Gewil (whole hide parchment), and the writing should be on the side which had been next to the hair.
Comment: Aside from the point that it can't be used on Shabbos and Yom Tov(!)
Comment: I'm not sure how this answers the question
Comment: Of course, but aren't there Chumashim with the Torah written not on parchment and websites with the complete text of the Torah? How is it different to give it a slightly different digital representation, as you have said (no different from any other online file.) And you are right there are those who would attempt to access such a thing on Shabbat and Yom Tov. Not pushing the idea to market, but B&H photo and ArtScroll both have ways of dealing with this (I know because I'm on a different continent and after Havdallah they are still enjoying Shabbat rest)
Comment: @DoubleAA, this appears to be addressing the last part of the post, which may be better off as a separate post.
Comment: @IsaacMoses And what halachic problem exactly is there exactly? Or is this saying there isn't a problem?
Comment: @DoubleAA I closed the question and commented asking for severance and clarification of that point.
Comment: @DoubleAA This seems to answer the unedited version of the question, which could be read as asking about an online Sefer Torah for ritual use
Comment: @JoelK Correct. I just saw the new version of the question, which makes my answer irrelevant.

Online Torah Scroll


Changed cooke domain cant login

Question: Hi there I changed cookie domain, which ovs typed in wrong. One article told me to remove it from PHPmyadmin but sitll cant login, I removed cookie sessions and everything
Answer: Check if the following steps work :-
1.Open /opt/lampp/htdocs/magentoprojectname/app/code/core/Mage/Core/Model/Session/Abstract/Varien.php
2.Find these 3 lines of code & comment them:-
<code> 'domain'   => $cookie->getConfigDomain(),
 'secure'   => $cookie->isSecure(),
 'httponly' => $cookie->getHttponly()
</code>
3. Try logging in
Are you able to login now?
Comment: I appreciate your help Ajay, thank-you very much.
Comment: You're welcome Ben. Did it solve your problem?

Changed cooke domain cant login


Administrator privileges in Windows Vista

Question: I have administrator privileges in Windows Vista.
Even then I have to run few programs as 'Run as Administrator'( by right click menu option)  to make them work successfully.
For e.g. I am able to build a Visual Studio solution only when I launch it by clicking 'Run as Administrator' (otherwise it says 'Access denied for files').Its the same case with few other programs like Command Prompt.
How do I make sure that by default all programs to be running as administrator ?
Comment: I have that problem too, where I want one (and only one) of my app to run under administrator mode sometimes because it checks if a new version is available and downloads it. To isntall it, I need that administrator privileges and I can only do this when I 'run as admin'. Really not a good thing because the persons that use it will be scared from such an issue.
Answer: You don't want all programs to run as administrator by default (that's sort of the point witt UAC).
Instead, edit the shortcut for those programs where you do need to run as administrator: right-click the shortcut, select the "Properties" command, go to the "Compatibility" tab and check the "Run as administrator" check box.
Comment: This is true, but it will still cause the UAC prompt to appear to authorize administrator rights.
Comment: You can set UAC to elevate without prompt.
Goto ->Control Panel -> Local Security Policy -> Local Policies -> Security options ->User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode.
Set it to "Elevate without prompt".
Answer: Are you sure you want to have your programs automatically run as administrator? That is a good way to give malicious or poorly written programs free reign to destroy your system. All other operating systems use a more restricted set of privileges than "root" (administator) when running standard programs; only Windows has, to its detriment, allowed programs to run as administrator by default, and now they finally fixed it.
A better approach might be to write to locations belonging to your user account, rather than generating output into a system directory. If it is failing as a result of reading from a system directory (e.g. where your header files are currently located), a better solution would be to change the permissions of those files (for example, to grant read-only access to all users), rather than running in an elevated privilege mode.
Answer: The trick here is that 'administrator privileges' is not the same as the Administrator account. You might notice that you can't copy and paste between a command prompt running as an administrator while you can if you run it under your own account.
You should be able to suppress warnings by logging in as Administrator, but then you're running everything as Administrator, including 'programs' that shouldn't have unrestricted, uninterruptable access to system functions.
Alternatively, I believe you can set some programs to always run as Administrator when launched. It's not comprehensive, but if you're just trying to avoid clicking through the UAC prompt every time you start up Visual Studio, that would be the way to go.
Answer: Vista has a feature called User Account Control that allows an Administrator to basically run as a limited/standard user account, but request elevated privileges when needed.
So, when you select Run As Administrator, you'll telling the system to give that application elevated rights.  Otherwise, the program runs with standard user rights and doesn't have access to much of the system.
For example, they cannot write to the Program Files or Windows folders.
To get all of your programs to run with full Administrator rights, it's possible to turn off UAC.  You should be careful as it removes the security feature.  Personally, I turn it off.


Random likelihood function during maximizing process

Question: Mostly common definition of Maximum Likelihood Estimator in certain parametric problem $(\mathcal{X},\mathcal{B}(\mathbb{R}^n),\mathcal{P}=\{\mathbb{P}_\theta\mid\theta\in\Theta\})$is what follows:
$$
\hat\theta_{MLE}(\mathbf{x})\equiv\underset{\theta\in\Theta}{\operatorname{argmax}}L_n(\theta\mid\mathbf{x}),\quad\forall\mathbf{x}\in\mathcal{X}
$$
It means that for all n-dimensional data points $\mathbf{x}$ we have unique solution, which maximize Likelihood function. Then, during the process of maximizing Likelihood is considered as non-random function of $\theta$, with data given. I am interested under what assumption we can treat the Likelihood as random in process of deriving estimator- i look for more formal, measure-theoretic approach to this problem. I think that the likelihood should be measurable function, differentiable in $\theta\quad a.s\quad\mathcal{P}$. Am I right? What else?
Comment: There is no need for the likelihood to be either measurable nor differentiable in $\theta.$ Insisting on that would introduce unnecessary restrictions and rule out the applicability of this theory in some significant situations.
Comment: The random function $L_n(\theta\mid\mathbf{x})$
should be measurable in $\theta$ (at the very least, to talk about existence of argmax you need more structure) $\mathcal{P}$-a.s. The argmax $\hat\theta_{MLE}$ should be a measurable function of data $\mathbf{x}$, as any estimator should be.
There is no requirement that $L_n(\theta\mid\mathbf{x})$ be jointly measurable in $\theta$ and $\mathbf{x}$.
Answer: Let $\left(\mathcal X, \mathcal A, \left(\mathbb P_\vartheta\right)_{\vartheta \in \Theta}\right)$ be a statistical model consisting of

a set $\mathcal X$ (the sample space),
a $\sigma$-algebra $\mathcal A$ on $\mathcal X$,
a family of probability measures $\left(\mathbb P_\vartheta\right)_{\vartheta \in \Theta}$ on $\mathcal A$ with
index set (the parameter space) $\Theta$ of cardinality bigger than one.

If, for all $\vartheta \in \Theta$, $\mathbb P_\vartheta$ is absolutely continuous w.r.t. a $\sigma$-finite measure $\mu$ on $\mathcal A$, then the likelihood function $\mathcal L$ is defined as the Radon–Nikodym derivative of $\mathbb P_\vartheta$ w.r.t. $\mu$:
$$
\mathcal L(\vartheta, x) \mathrel{:=} \frac{\mathrm d \mathbb P_\vartheta}{\mathrm d \mu}(x), \; \forall \, \vartheta \in \Theta, x \in \mathcal X,
$$
and often viewed as a function in $\vartheta$.
Thus, the (random) likelihood process is the random process of the corresponding Radon–Nikodym derivative.


System app Uninstallation without rooting

Question: How to Uninstall system apps without rooting? I have tried many applications but all of them require root permissions. Please help.
Comment: You can't. They are system apps for a reason.
Answer: You can't uninstall them without root. You can disable them, though.
If space is your concern, get an SD Card. If memory is your concern, Disable them.
or You could Root your device.


How do I calculate the autocorrelation of a train pulse having only the pdf?

Question: I have a pulse train of a fixed period, but a random amplitude following a Gaussian distribution $(\mu=0,\sigma=1)$. I know how to work with a random period or delay, but how do I proceed to calculate the autocorrelation with a random amplitude?
Answer: Suppose that your pulse train is denoted $X(t) = Y\cdot g(t)$ where
where $g(t)$ is the basic pulse train and $Y$ is the random
amplitude of the pulse train.  Then, $X(t)$ is not a
wide-sense-stationary process and its autocorrelation function is
$$R_X(t_1,t_2) = E[X(t_1)X(t_2)] = E[Y^2]\cdot g(t_1)g(t_2).$$
If $Y$ has mean $\mu$ and variance $\sigma_2$, then
$E[Y^2] = \mu^2+\sigma^2$.  If $g(t)$ is a function of period $T$,
that is, $g(t) = g(t+T)$ for all $t$, then $R_X(t_1,t_2)$ is
periodic in both arguments:
\begin{align}
R_X(t_1+T,t_2) &= (\mu^2+\sigma^2)g(t_1+T)g(t_2)
= (\mu^2+\sigma^2)g(t_1)g(t_2) = R_X(t_1,t_2)\\
R_X(t_1,t_2+T) &= (\mu^2+\sigma^2)g(t_1)g(t_2+T)
= (\mu^2+\sigma^2)g(t_1)g(t_2) = R_X(t_1,t_2)
\end{align}
I am quite sure that this is not what you hoped to hear and so you
must revise your question appropriately, giving more details and
describing more clearly what it is you want to find out.
Comment: Actually, this was the answer I was looking for. I was making a silly mistake before. Thanks!


Has anyone ever tried to replace an RTE in Sitecore, with something custom like tinyMCE? If there is there any instructions?

Question: I would like to replace the default RTE in Sitecore with tinyMCE, how would I do it? Where do I start?
Answer: I went down this path in this question. To this point I don't think anyone has pulled it off. And its mainly because there is so much Sitecore functionality in the RTE (i.e. Links, photos, etc...) Your best bet it to just allow the editors to have a custom HTML editor similar to what Michael West did. You can wire in your client side editor the same way Mike did.
See his module here http://marketplace.sitecore.net/en/Modules/Code_Editor.aspx
A great video on it here http://youtube.com/watch?v=JgOSdjgG_qs
Answer: I faced the same question some time ago. The good starting point for me was taking Emanuele Ciriachi module and extending it.
Then I did:

Unicorn serialization
Using npm for getting TinyMCE
Updating TinyMCE to the actual version
CI/CD setup
Sonar cloud configuration
Mix of Sitecore classic RTE and TinyMCE RTE
Sitecore 10 support
Switch to Nuget packages for referencing Sitecore assemblies
Improved development setup

Now the instruction on how to replace Sitecore RTE with TinyMCE is as simple as possible.

Open Update Installation Wizard
Install TinyMCE package
Change field types

Or if you need to use another editor, not TinyMCE, you can take sources as a starting point and replace TinyMCE with RTE that you prefer.
Answer: I'm supporting a Sitecore 6.5 site where TinyMCE has been used to replace the default rich text editor.
This article covers the setup https://sitecore.wordpress.com/2009/02/20/sitecore-forum-module-using-tinymce-instead-of-freetextbox/
Comment: Please update your answer to have more details on how you implemented your solution. As it stands now you have only provided a link and the link may or may not exist in the future which won't be helpful when someone comes to this question on how to replace the RTE.
Comment: The article also only covers replacing it in the forum module, which may not have been using the Telerik one the main CMS uses. Looking at the code, it's not enough to replace the main one.


why does the legend or code or elements computer stuff pop up when I press increase volume?

Question: So, I don't know what exactly I did but all of a sudden I couldn't hear sound through my headphones. I had checked if the volume still works and it does. It turns out the volume on my headphones was mute but that didn't fix my problem as when i pushed the increase volume button on the keyboard a side popped up that looks like legend or code or something. None of the top row buttons work properly. Brightness doesn't do anything. I mean when i press it the brightness doesn't go up or down. When I press decrease volume the screen is goes to like that area where it shows you your desktops and open windows. I need help please.
Answer: Reading between the lines a bit…
you need to uncheck 'Use F1, F2, etc. keys as standard function keys' in System Prefs > Keyboard


A/B testing in Journey Builder

Question: We would like to use A/B testing in Journey Builder. I saw there was no such option out-of-the-box, but is there a workaround? When I say "A/B Testing", I don't mean just having a random split to monitor which of the 2 email versions has a better-performing e.g. subject line. Rather, we'd like a standard A/B functionality from Email Studio, whereby Marketing Cloud evaluates how each version of the e.g. subject line performed on the 20% list, and sends the "winning" version to the remainder of the list (80%) automatically.
Comment: you can use Random Splits to build A/B testing in JB.
Comment: Hi Nix, can you update your question to specify that you want the AB test to resolve in a "winner" (after a period of time?) rather than just producing an ongoing random split?
Answer: Yes, the most simple way is to use a Random Split.
After you randomly split the contacts, you can define the Email Activity and use the same email with different subject lines, or add a Wait activity to send it at different times.
The downside of this is that you will have to figure out a way to create reporting, which won't be as easily displayed as the one in the A/B Test in Email Studio. As a workaround, you could include Engagement Splits in your journey, just before the Exit, to see how many subscribers engaged with each version of your email.
Comment: Hi zuzannamj, yes that's the workaround that we though of too, but the downside is that the system does not determine "the winning" version of an email and sends it to the remainder of customers. Or am I not seeing the potential of random splits here?
Comment: Yes, you are right, the only way to achieve that using the built-in functionality is to use A/B Test in Email Studio: https://help.salesforce.com/articleView?id=mc_es_abtest_configure.htm&type=5
Answer: I think the easiest way to achieve this would be to random split your audience, then use dataviews to determine the engagement and reflect that in the email sent to the remainder of the audience then join them back to the main group then repeat the pattern. the top email would be which performed better out of the bottom 2 emails.
Comment: Could you tell me how I could configure the first email in the random split 80% path. The first email could be blank or I need to configure with anything or it is something will be taken automatically? I am thinking to use it.
Comment: you can do this pretty easily with path optimizer in journey builder, you don't even need to make a query. remove the first path. take 20% of your audience run them through the 50/50 split and the winner will be determined automatically.
Answer: This question was asked in 2019, but Path Optimizer became available in May 2020. Path Optimizer should allow you to do the A/B testing functionality that you are seeking, but it should be noted that Path Optimizer goes far beyond A/B testing; in fact, you can have up to 10 paths in a Path Optimizer flow control.

A/B testing in Journey Builder


Gradient Ascent vs Gradient Descent in Logistic Regression

Question: I've been going trough Machine Learning in Action book from manning (https://www.manning.com/books/machine-learning-in-action)
In the logistic regression chapter it uses gradient ascent to calculate the best weights.
Why do we pick gradient ascent instead of gradient descent ?
Comment: To find a maximum rather than a minimum.
Comment: I think the different rather reflects on engineering perspective, gradient descent always uses on a minimization setting that minimum is bounded somehow (for example negative log likelihood is bounded by 0).
Answer: https://en.wikipedia.org/wiki/Gradient_descent:

To find a local minimum of a function using gradient descent,
  one takes steps proportional to the negative of the gradient (or of
  the approximate gradient) of the function at the current point.
If instead one takes steps proportional to the positive of the
  gradient, one approaches a local maximum of that function; the
  procedure is then known as gradient ascent.

In other words:

gradient descent aims at minimizing some objective function: $\theta_j \leftarrow \theta_j-\alpha \frac{\partial}{\partial \theta_{j}} J(\theta)$
gradient ascent  aims at maximizing some objective function: $\theta_j \leftarrow \theta_j+\alpha \frac{\partial}{\partial \theta_{j}} J(\theta)$
Answer: What is a gradient?
It is a derivative of a function at a certain point. Basically, gives the slope of the line at that point. How to calculate this slope geometrically(just consider a 2 D graph and any continuous function)? You draw a tangent at that point crossing x-axis and a perpendicular to the x-axis from that point. It will form a triangle and now calculating slope is easy. Also if this tangent is parallel to x-axis the gradient is 0 and if it is parallel to y-axis the gradient is infinity.
Why use ascent or  descent?
If I have a function which is convex then at the bottom the gradient or derivative is 0. Similarly, if we have a concave function at the top gradient or derivative is 0. Why are we interested in 0? This is because it helps us find either the lowest(convex) or highest(concave) value of the function
Now our machine learning has a cost function and they can either be concave or convex. If it is convex we use Gradient Descent and if it is concave we use we use Gradient Ascent. Now there are two cost functions for logistic regression. When we use the convex one we use gradient descent and when we use the concave one we use gradient ascent. Also, note that if I add a minus before a convex function it becomes concave and vice versa.
Answer: @Franck is correct, they are the same thing other than the sign is positive or negative. There is good explanation in the book:
Answer: If you want to minimize a function, we use Gradient Descent. For eg. in Deep learning we want to minimize the loss hence we use Gradient Descent.
If you want to maximize a function, we use Gradient Ascent. For eg. in Reinforcement Learning - Policy Gradient methods our goal is to maximize the reward function hence we use Gradient Ascent.


Would it be practical to have missiles that can aim forward and backwards?

Question: I have been researching recent air-to-air combat kills in some recent wars and in every case it seemed that the pilot who was in the back won. So I was wondering why they don't just design a missile capable of swiveling around and targeting a bogey behind the aircraft. I understand there are some physic issues with it but surely it wouldn't take long for physicists and engineers to come up with a solution
Comment: As an alternative, one could have one missile permanently mounted for reward firing with a missile specifically designed & shrouded for reverse flight. Of course, you're then wasting a launch rail, fuel, range, speed & maneuverability for something that might be used in <1% of encounters and only in a situation that you're explicitly trained to not allow to happen. (It does happen, of course, but you're not supposed to allow the bogey to get behind you.)
Comment: *but surely it wouldn't take long for physicists and engineers to come up with a solution*: it is a common misconceptions. Engineering is about finding trade-off: you can have many things, but you should sacrifice a lot more things. Really: real world is much more complex and we cannot have everything.
Comment: I was under the impression that most newer missiles can attack targets all around the aircraft. The IRIS-T (developed 2001) can attack targets 360° around the airplane, at least when mounted on the Eurofighter Typhoon. (But I believe not when mounted on the F-16 because it lacks the necessary sensor integration.) That's a 20+ year old missile and it already has the feature you ask for. Same for the AIM-9X Block II (2010s).
Comment: Imagine the drag of that missile when it's 90° to the chasees current direction of travel. Holy drag & vibration, Batman!!
Comment: Well, you could have a missile inside a missile.  The outer missile would be designed to fire backwards off the launch rail.  The big fins would be in the front of the missile, and the little fins (if any) would be in the back.   Once the outer missile has accelerated to zero airspeed, the inner missile fires out of it.  The inner missile breaks out through the frangible nose cone of the outer missile, the folding fins unfold, and there you go.
Comment: (Or simpler, just have a missile pointing rearward on the launch rail, with an extra set of large fins at the nose of the missile, that get jettisoned once the missile has accelerated to zero airspeed.)
Answer:
So I was wondering why they don't just design a missile capable of swiveling around and targeting a bogey behind the aircraft.

They did. The AIM-9X is able of doing precisely that.
The caveat is, you're looking at much lower kill probability (Pk).
Studies indicate short-range IR-guided missiles to have a Pk as high as 74% when launched normally, at a visually acquired aircraft in front.
Doing a 180 turn exposes the missile to the same kill-chain failures that BVR (Beyond-Visual-Range) missiles normally face. Missile seekers have a narrow field of vision, and there's little time to search. Unless the missile happens to catch the target just right when it turns, it's going to fly past. This brings expected Pk to the same 10%-25% range as BVR missiles in challenging conditions. That's not enough when you're only carrying two short-range missiles.
Lock-on-after-launch capability was initially introduced for internal storage on stealth aircraft, and only later adapted for a possible backward engagement. It's necessary for any stealth aircraft, but most missiles aren't designed to do a full 180.
The AIM-9X is not the only one. As always, there's few military ideas imaginable that the Soviets haven't tried at some point. They have apparently decided it's not worth pursuing, but apparently they had at least a concept for a rear-firing missile. There were similar ideas in the US as well. We're rapidly entering speculation here however.
Out of related concepts, the Flanker comes with a rear-facing radar. The new Su-57 has both front- and rear-facing laser turrets to blind attacking IR-guided missiles. But no rear-facing missiles. Instead, the idea for it is to use the very risky Cobra Maneuver to trade places with the pursuer.
Comment: @AnonymousPhysicist - "is used for dogfights" might actually be "has never been used in actual combat".
Comment: @AnonymousPhysicist Short-range missiles are used in dogfights.
Comment: Your link says the Cobra maneuver is used for dogfights, which means no missiles.
Comment: @AnonymousPhysicist In no way does "dogfight" imply guns only.
Comment: "The AIM-9X is not the only one." – The German IRIS-T, for example, can attack targets behind the aircraft, at least when fired from an Eurofighter Typhoon. The missile can also be used on F/A-18, F-16, Gripen, and Tornado, but at least for the F-16, it cannot use its full potential, including 360° targeting, due to lack of sensor integration.
Answer: That is a whole lot of machinery to design a swivel missile launcher rail. Things that can fail.
Then, a different missile to be launched at a starting speed of 'minus 500 mph" or so. Backwards.
If the enemy is behind you, you've already lost. In the time it takes you to rotate that launcher...his missile is already in the air, chasing your tailpipe.
Another thing you're probably missing is that air to air combat is rarely 1 v 1. There is almost always a wingman.
Comment: @FreeMan - Yes, but differently pivot. In a former life, I was a WPNS guy on F-111E. Much experience with the pivot pylons. Major PITA. I can only imagine the maintenance nightmare with a wingtip rotatable launcher. Is it possible to design and build? Sure. But since we've not seen one yet, no one has thought it worth the effort.
Comment: I'm virtually certain that this concept has been brought up many times in the history of combat aircraft. And the senior members of the design team said "Yeah, we looked at that 20 years ago. It was a bad idea then, it is a bad idea now."
Comment: Swing-wing aircraft do have launcher rails that pivot, so it _can_ be done. Probably not particularly efficiently, though. Of course, swing wing aircraft don't have the wings go through 180° of rotation.
Comment: Oh, I agree 100% _Anything_ is _possible_, but practical, economical, real-world feasible? Not so much
Answer: Typical missiles have fins in the back that are used for steering.  If the missile is launched towards the rear of the aircraft, it will have a tail wind.  Then the fins will be destabilizing instead of stabilizing.  The missile will quickly become a bunch of missile parts.
It would be possible to design an air launched missile that did not have this problem.  In practice, ground launched missiles work fine.
Comment: Actually, many/most air to air missiles have the steering fins at the front. AIM-9 and AIM-120, for example. Not that it makes a real difference, though.
Comment: Which fins are static and which steer indeed doesn't matter.  You're firing an arrow backwards, and the few moments it spends at "negative airspeed," while trying to reach designed airspeed, are enough to make it tumble, possibly into your own airplane.  Recall the test pilot who lived to tell the tale of shooting himself down.
Comment: @WPNSGuy Where are the fins at the front of this AIM-120? https://media.defense.gov/2003/Mar/28/2000031135/-1/-1/0/030328-F-JZ000-019.JPG
Comment: Static fins at the rear are a very important part of the steering system.
Comment: @AnonymousPhysicist - Frontish. On the -120, more to the middle. The fins at the rear are static, and do not steer/swivel. Maybe I should have said "towards the front", instead of "at the front"
Answer: The M2 Browning certainly does not have a problem firing forwards or backwards owing to its Mach 2.5+ muzzle velocity.
A rearward fired missile could theoretically be propelled away from the aircraft fast enough to gain net positive forward velocity.
Rocket augmented artillery shells are already in existence, potentially increasing the M2's already impressive 2000 yard effective firing range.
One might wonder if an updated version of the B-29 computer fire control system with upgraded shells and a ball turret could do  against an upcoming Stinger missile.


Configuring Quercus to talk to JavaDB

Question: I am trying to get the Quercus PHP engine to connect with the JavaDB. I have successfully deployed Quercus in Glassfish, but I can't get Quercus to successfully connect with my database in JavaDB. Can anyone point me to an article or tutorial that treats this subject?
Answer: Alternatives are describe here:
http://www.caucho.com/resin-3.1/doc/quercus.xtp#databases
The jdbc driver should be include in the Derby distribution (/lib/derbyclient.jar).

Configuring Quercus to talk to JavaDB


How to emulate skins (from ASP.NET) in windows forms

Question: Here is the problem. i am developing a windows forms application in c# that has a lot of forms that include datagridviews, and i want to all those gridviews have the same look, same background color, same header alignment, and a lot of other properties.
in ASP.NET it is easy to do with skins, but how can i do this in windows forms?
Answer: Create  a user control. Assign the properties whatever you want and then inherit that user control in the forms. Hope this will fix your problem
Answer: I think the best would be to use 3rd party cntrols like devexpress. They have rich skin support and skin editor


Wilde's imaginary name Bunbury: absurd?

Question: In The importance of being earnest by Oscar Wilde, a man imagines a person by the name Bunbury, so another man calls that name absurd. Is it really? And why?
Comment: No real idea, but it might be relevant to note that Henry William Bunbury was a famous caricaturist. Though he died in the early 1800s, his work---and the history books written by his son Sir Henry Bunbury---would likely have been known to Wilde. The latter's writing was known for having a sense of humor. Although "bun" as in "buttocks" is from the 1960s, it had a colloquial meaning in Wilde's time of "tail of a hare."
Comment: It may well have been a joke/pun, since many of Bunbury's caricatures were likely considered absurd at the time.
Comment: I'm voting to close this question as off-topic because it is about a (possibly made-up) name, not actual language.
Answer: My guess is that Bunbury is meant (by Wilde) to sound more like a village famous for its hot cross buns than like someone's surname. A footnote to the word Bunburying in the Wikipedia treatment of The Importance of Being Earnest reports that Wilde used the name as an inside joke:

"Bunburying", which indicates a double life as an excuse for absence, is—according to a letter from Aleister Crowley to R. H. Bruce Lockhart—an inside joke that came about after Wilde boarded a train at Banbury on which he met a schoolboy. They got into conversation and subsequently arranged to meet again at Sunbury.

But on the other hand, in a continuation of the same footnote, another writer concludes that Bunburying has a different source:

Carolyn Williams in a 2010 study writes that for the word "Bunburying", Wilde "braids the 'Belvawneying' evil eye from Gilbert's Engaged (1877) with 'Bunthorne' from Patience.

In any case, when Jack says, "So I am going to get rid of Ernest. And I strongly advise you to do the same with Mr ... with your invalid friend who has the absurd name," he may be reacting in irritation to the idea that his imaginary Ernest is of a piece with Algernon's Bunbury—and in his irritation, he may temporarily have forgotten the imaginary invalid's name and recalled only that it sounded a bit odd. Or he may be exasperated by the idea that he is to some extent going along with the fiction of Mr. Bunbury when he refers to him by his given (by Algernon) name instead of calling him "your imaginary invalid" or something like that.

Wilde's imaginary name Bunbury: absurd?


Schwarzschild radius in matrix models

Question: The Schwarzschild radius for 11D BHs is given by $l_{11}(l_{11}m)^{1/8}$, which is the special case ($D=11$) of the general dimensional case of $(G_Dm)^{\frac{1}{D-3}}$. Here $m$ is the BH mass and $G_D$ is $D$ dimensional Newton's constant. Now if M-theory is compactified on a torus $T^p$ of sizes $L$s, then I think $G_D$ is related to eleven dimensional Planck length $l_{11}$ as $G_D=\frac{l_{11}^9}{L^p}$. I don't understand how can then the radius smoothly go to the 11 dimensional value if we start decompactifying the torus to get to the 11D case. It seems that it blows up. Where's my mistake?
Answer: The formula you have used in general dimensions would only be valid when the Schwarzschild radius (dictated by the mass of the black hole) would be much larger than the compactified dimensions. When you start making L larger to decompactify the torus, the formula starts becoming a worse approximation until it breaks down when the black hole is approximately the size of the compact dimensions.

Schwarzschild radius in matrix models


Area under a displacement graph

Question: If the area under an acceleration-time graph denotes velocity and the area under a velocity-time graph denotes displacement, what exactly does the area under a displacement-time graph denote?
Comment: A note on the "area under a graph" in teaching physics: I presume you are learning from a calculus-free source, in which case the "area under the graph" constructs that you're going to see several times are a way of representing integrals without having to teach you calculus. Or we could say that a definite integral is a notation for the area under a graph which is more in line with the historical development. In any case, there is no guarantee than an arbitrary integral has physical significance, we know which ones do empirically (i.e. they're useful in solving problems).
Comment: In one problem that was presented in our text, the area under the positive half of the position time graph was the same as area in the negative half, and the displacement was zero. Perhaps, that helps students understand displacement of 0.
Comment: See https://en.wikipedia.org/wiki/Absement for more information
Answer:
what exactly does the area under a displacement-time graph denote?

I think it just represents what you said: the area under a displacement-time graph. I can't think of any other use for it. There are two main reasons for this:

Your quantity, let's call it $f(t)$, retains a memory of where the object has been. That's because the area under the graph depends on the entire past history of the graph, and not just where the object is now. This flies in the face of the principle that physics is local in time: what happens next is determined entirely by the state of the system now and doesn't depend on what happened further back. This is called the Markov property of the laws of physics, and is a general feature of all the fundamental laws we know (relativity changes this in detail, but not in any essential way). There are examples of systems which are approximately non-Markovian because they interact with their environment in a way that preserves a memory, but this isn't the norm, and you can always get a Markovian description by including the environment as well. $f(t)$ might play some small role in the theory of such systems, but only in an approximation where you leave out the environment.
Because of translation invariance (the laws of physics are the same here as anywhere else) there is no meaning to "absolute" position, only differences between positions matter. This means $f(t)$ is redundant: you can add an arbitrary linear function of time $f(t)\to f(t)+ u + w t$ and still get the same physics. This restricts the way $f(t)$ can appear in the laws of physics, leaving you with nothing new that isn't already recorded by position, velocity and acceleration.
Comment: To add to the answer, OTOH, you might encounter systems (not Newtonian mechanics, but like say.. some electrical circuits) where the system might have memory. In such cases, I think $f(t)$ or analogous quantities might be useful.
Answer: I don't see this quantity computed very often so I don't think it is that useful, but here is one thing that can be said: If $A$ is the area under the graph and $T$ is the duration of time over which the integral was preformed then $A/T$ is the average displacement from the origin during that interval of time.

Area under a displacement graph


Can a DXA resources component contain embedded schemas?

Question: I would like to make a resources/labels schema which uses a custom configuration schema with embedded and multi-value embedded fields. Will the @Html.Resource("module.resourceidentifier") be able to grab embedded fields?
Answer: As documented http://docs.sdl.com/LiveContent/content/en-US/SDL%20DXA-v7/GUID-5DED64BE-E71B-4C64-8131-151D336AAA08
A resouce/label Component can use the General Configuration Schema, or you can create a custom Schema. The General Configuration Schema uses an Embedded Name Value Pair Schema, which validates that you can use Embedded Schemas.
However depending on what you exactly want (which you fail to describe in your question), it might or might not work.
In case you wanted to use an Embeddable Schema for grouping, might I suggest to simply use multiple resource/label Components, since you don't have to store all your resources/labels for a module in a single Component (so that we can keep it more manageble also during translation, and possibly even reuse the same resource/label Component for multiple modules.
Comment: Thanks Bart, I updated the question for clarification. It a custom schema with embedded and multi-value embedded fields. The documentation does not describe limitations to a custom resource schema, but it also does not describe how @Html.Resource() would address an embedded resrouce field or a multivalue embedded resource field.
Comment: @JanH there is basically only support for key value pairs, so maybe you should update your question with some more details and a description of why you need this, because I'm not sure what exactly you want to use.
Comment: I have two use cases in a real life implementation.
The first is separation of fields with an embedded schema, i.e we have single and plural date labels, separators etc. Those are all related but could be nicely grouped in embedded schemas for clarity. This is the grouping use case you mentioned in the answer. This could be split in multiple components which will also bloat the number of components. Over all schemas the reource key will have to be unique as well since the resource id for `Html.Resouce` takes the fieldname.
Comment: The second use case is a language selector. The site localization in `WebRequestContext.Localization.SiteLocalizations` is not exensible, so I like to create an additional localization configuration which must hold a multivalue embedded field with fields additional site configuration. I solved this one by using a normal component instead of a resource component.
Answer: Resource components do not support embedded fields or multi value embedded fields for custom schemas. Html.Resource("module.resourceidentifier") will not retrieve embedded fields on a custom schema.
The key-value pair configuration schema uses a multi value embedded field, but all values from both key-value pair and from custom resource schemas are flattened into one list, published and retrieved in the website in the same way.
In fact the field name, or key, needs to be unique in the module: in Html.Resource("module.resourceidentifier") the "module" is the lowercase module name and "resourceidentifier" is the cased field name or key.


Potassium from Potassium superoxide

Question: Is it possible to get $\ce K$ from $\ce K{O_2}$ using a synthesis reaction? If yes, can you describe it?
Comment: I suppose easier and/or cheaper ways are preferred. KO2 assumes it has (probably) already been K once. It is like to isolate K twice. // Attempts to post the most laconic question ever are at risk they will be closed and most users will not notice them.  [How do I ask a good question](https://chemistry.stackexchange.com/help/how-to-ask).
Comment: $\ce{KO2}$ is a dangerous and explosive substance. Don't use it. Better destroy it in large amounts of water.
Answer: Thermal decomposition should help but it requires very high temperature. It goes through various oxides and ultimately decompose to potassium.
$$\ce{KO2 ->[<400 ^\circ C] non-stoichiometric oxides ->[400-480 ^\circ C] K2O2 ->[500 ^\circ C] K2O ->[560 ^\circ C] K (+oxygen ^)}$$
Do note the reaction is performed in vacuum otherwise it can oxidized back to peroxide/superoxide.
Ref. STUDIES OF THE THERMAL DECOMPOSITION OF THE POTASSIUM OXIDES IN THE TEMPERATURE RANGE 300--480 DEGREES C, RILEY, JOHN F. 1968. (link)

Potassium from Potassium superoxide


Nearly finished UVHM in duo, but still in TVHM solo, how can i skip?

Question: My friend and i finished True vault hunter mode and is ATM lvl 52 on Ultimate vault hunter, but in my solo game i've only just started TVHM. Is there a way to skip to UVHM? Open for everything.
Comment: Pretty sure the only way is to beat the final boss, so if you want to skip through it quickly you could try getting your friend (and his highly-leveled character) to play with you and race through the story mode.
Comment: Alternately, I'm pretty sure (at least for PC) there's a save-game editor somewhere, but it's been a year or two since I've played so I'm not sure where I'd find it. Keep in mind that using it would rob you of the EXP you'd have gained along the way, though.
Comment: Thank you, ill try to look into the save-game editor. Cant be bothered to play through the whole game being 20 lvl ahead:)
Answer: If you're any less than level 50, the easiest thing to do is probably to just play through TVHM's main storyline. Ignore every side quest. You'll be so overleveled for the content that you should blow through, especially if you have weapons at your level. Plus, as soon as you get to UVHM, everything will be level 50 minimum, and if you're not at 50 yourself yet, you'll be in instant trouble - every enemy will soak tons of bullets and feel like its own mini-quest to kill.
If you're at 50, and don't have weapons at or very close to that level, find some before you tackle UVHM. Anything at even 49 or less will start to have trouble. (The higher the rarity, the longer it'll last, and some weapons will survive especially long, such as a DPUH.) Buy greens from a vending machine if you must.
If you're 50 and have leveled weapons, then a save editor might work, but I'm not sure. I found an editor on NexusMods. I can't tell from the screenshots whether there's any info there on which game mode you've unlocked, but if it's anywhere, it seems to be in that editor's Raw tab. Hope you're comfortable with Regedit.