What happens when two entangled particles are not measured synchroneously?

Question: Suppose we have a pair of entangled photons, one photon sent to Alice and the other to Bob. A and B are at rest in the same reference frame. When A receives and measures the polarization of her photon, the photon sent to B is still traveling and he measures its polarization later. Does B's photon acquire its correlated polarization instantaneously when A measures her photon, or when B makes his measurement later on?
Comment: How would you tell the difference?
Comment: @ReneKail as far as we know, the collapse is instantaneous for the entangled photon.
Comment: see this answer  https://physics.stackexchange.com/questions/446671/how-do-we-know-that-two-quantum-states-are-entangled/446683#446683
Comment: A great extreme case for this is the Delayed Choice Quantum Eraser, which has actually been executed and we've confirmed the results are in line with the predictions of QM
Answer:
Suppose we have a pair of entangled photons, one photon sent to Alice and the other to Bob. A and B are at rest in the same reference frame. When A receives and measures the polarization of her photon, the photon sent to B is still traveling and he measures its polarization later. Does B's photon acquire its correlated polarization instantaneously when A measures her photon, or when B makes his measurement later on?

If you measure one photon of a spatially separated entangled pair of photons, nothing happens to the other member of the entangled pair. The relevant equations of motion are Lorentz invariant so the motion of the systems concerned can't depend on the order of spacelike separated events since that order isn't Lorentz invariant. The expectation values of measurements on each photon don't change as a result of measurements on the other photon.
If we take the equations of motion of quantum theory as an accurate description of reality, then the correlations arise after information about the results have interacted with one another. Decoherent channels such as records on a computer or signals in a wire carry quantum information about those results even though the expectation values of their observables don't depend on that information: this is called locally inaccessible information
https://arxiv.org/abs/quant-ph/9906007
It is common to say that quantum mechanical equations of motion are not accurate as a description of reality, or to fudge that issue. As a result, most accounts of entanglement don't give any explanation of how correlations arise and even when they do they rarely provide any substance about the alleged mechanism such as wavefunction collapse or whatever.
Comment: @DrChinese If you want to say anything about what's happening in reality, you're picking a particular "interpretation". Simultaneity for spacelike separated events is frame dependent. Lorentz invariance is relevant to quantum theory, see e.g. Chapter 9 of "Quantum Field Theory for the Gifted Amateur" by Lancaster and Blundell and "The Quantum Theory of Fields Volume 1: Foundations" by Weinberg.
Comment: The sentence I wrote that mentioned Weinberg was about Lorentz invariance not the MWI per se. I explicitly say that I am assuming that quantum mechanical equations of motion are an accurate description of reality. Every non-MWI "interpretation" either explicitly sez they are wrong or fudges the issue. I don't mention the MWI for much the same reason that I wouldn't mention interpreting GR in terms of curved spacetime: there is no serious alternative.
Comment: Yet another disguised attempt to push a particular interpretation of QM, in this case MWI. Actually, no one knows the mechanism of how measurements on widely separated particles stay synchronized, but we know from Bell's Theorem that the process cannot be causally or deterministically local. Normally, Bell tests do not operate on the entangled pair simultaneously. However, since Lorentz invariance is not in any way, form or fashion relevant to the predicted quantum outcome (in complete opposition to what you say), ordering doesn't matter.  At. All.
Comment: Believe me, Weinberg doesn't talk about MWI or any "interpretation" in your reference. If you're so proud of your personal interpretation choice, why not disclose it up front? That way unsuspecting readers aren't led astray by your comments.  Simultaneity being frame dependent is sometimes relevant in QM, but not with entanglement.
Answer: As tparker points out in the comment I just upvoted, there is more than one observationally equivalent way to model this.  But according to standard interpretations, your measurement collapses the pair into a new state, the new state is unentangled, and therefore you can say that from that moment on the second particle has a state of its own.  Of course you can't expect that state to necessarily be an eigenstate of some measurement that nobody's yet made.
Comment: @PhysicsDave :  Nobody said anything about communication.
Comment: Yes, this corresponds to the conclusion I came upon after some reflection.
Comment: It's worth clarifying that by "standard interpretations" you specifically mean the Copenhagen interpretation. In the many-worlds interpretation, the wave function collapse is not instantaneous but gets "transmitted" at or below the speed of light.
Comment: @tparker so are we saying ftl communication is the reality? Or just the interpretation implies ftl?  …. The interpretation thereby being somewhat implausible?
Comment: @ReneKail so are we saying ftl communication is the reality? Or just the interpretation implies ftl? …. The interpretation thereby being somewhat implausible?
Comment: @WillO  " Does B's photon acquire its correlated polarization instantaneously" from the op implies it.
Comment: @PhysicsDave :  Exactly what do you suppose is being communicated, and to whom?
Comment: @WillO let them answer if ftl exists …. If it doesn't then no worries.
Comment: @PhysicsDave In both the Copenhagen and many-worlds interpretations, faster-than-light *communication* of information or causal influence is impossible. In the Copenhagen interpretation, faster-than-light *establishment of correlations* - or, phrased more naturally, the establishment of correlations between spacelike-separated events - is possible. In the MW interpretation, the establishment of correlations between spacelike-separated events is impossible.
Comment: @tparker Correlation for example being; traveling around the world and looking in your purse and only seeing one right handed glove and instantly knowing the one that remains at home is left handed, i.e. the correlated one ?
Comment: @PhysicsDave No. These correlations are fundamentally different than that. Look up Bell's theorem.
Answer: I think remarkably in order to uphold Heisenberg Uncertainty and Quantum Mechanics Together,
It must be that given particle A and Particle B are entangled:

When one measures a property of particle A, at that moment in simultaneity the property measured in Particle A is 100% correlated in particle B instantly, and with no travel time, no delay

The collapsed state of Particle A and hence B as well was not only undeterminable in any shape or form before the measurement was taken, but the angle and property measured from Particle A made a difference in the outcome of the measurement of Particle A and hence the closer to that time Particle B is measured using the same property, the state observed matches exactly what was learned from particle A.

After the measurement of particle A, Particle B is no longer entangled to Particle B which means the longer particle B same property isn't measured in particle B, the more it won't correlate to Particle A since its new wave probability is now disentangled

Any other property of Particle B that is measured during or after the collapse of Particle A, will be specific only to Particle B,
Comment: a) The difference in time of measurement of 2 entangled particles has no significance at all, other than if the second interacts with something prior to its measurement.  b) There is no evidence that measurement of the first particle affects the second particle as opposed to vice versa; that is by assumption only.  c) Distance is not a factor either. d) Particles can be entangled on multiple bases. If so, it is possible to collapse on one basis without causing collapse on another.


Relation between port, port number and protocol?

Question:
Is a "port"  a communication endpoint (in the transport layer)?
Is a "port number"   an address assigned to a port?
Given a port, can we change the port number assigned to it, similar to
that it is possible to change the IP address assigned to a network interface?
From https://en.wikipedia.org/wiki/Network_socket

sockets with TCP port 53 and UDP port 53 are distinct sockets

What does the quote mean? Specifically,

Can a port be used by two transport protocols (e.g. TCP and UDP) simultaneously? (My understanding is that a port is part of a
transport protocol, and can't belong to another protocol even at a
different time.)
Does the quote mean that a port number 53 can be assigned to a port in TCP  and to a port in UDP at different times (but not
simultaneously)?
Comment: Related and possibly helpful: http://stackoverflow.com/questions/152457/what-is-the-difference-between-a-port-and-a-socket
Comment: An analogy is calling two different companies using the same extension number.
Comment: @teppic: do you mean TCP port 53 and UDP port 53 are two distinct ports?
Comment: @Tim Yes, you can use them for different things simultaneously. But well known apps will typically use the same port numbers if they use both.
Comment: Although a port cannot be used by two processes simultaneously, it is only a convention to run specific protocols on specific ports. Technically, there is no restriction to the ports a specific protocol can be used on.
Answer: TCP and UDP are two different protocols on top of IP. The TCP port number is part of the TCP protocol, and the UDP port number part of the UDP protocol. So yes, the two can be used simultaneously, as TCP and UDP are two different protocols, with different protocol numbers (see /etc/protocols).
A DNS server can and does listen to both UDP/53 and TCP/53, at the same time, as UDP is faster and has less overhead for everyday requests, while TCP may be necessary for especially large DNS requests, on account of UDP packet size limits from way back when. Here's named listening on both, at the same time, for example:
$ sudo lsof -i -nP | fgrep \*:53
named    1267  named   20u  IPv6    9691      0t0  TCP *:53 (LISTEN)
named    1267  named  512u  IPv6    9690      0t0  UDP *:53
$

This named can serve hundreds, or even thousands of simultaneous UDP and TCP client requests via the two distinct ports listed above.
TCP and UDP otherwise are two distinct implementations of a transport layer, and bear two fields of sixteen bits each that specify the source port and destination port for each TCP or UDP packet. The port number to name mapping relationship could be fiddled with by adjusting the /etc/services file (probably a very, very bad idea), or a server could be instructed to listen on some not-default port number, assuming the client systems are all properly reconfigured to connect to it at that non-default port number, e.g. sshd -p 1234 on a server and then ssh -p 1234 server to connect to that not-default TCP port 1234, instead of the usual tcp/22. Or, a DNS server could be set to run at UDP port 8475, though then one would need to use a custom client program such as dig -p 8475 @server ... to query that custom UDP port, as operating systems in general will only chat up UDP/53 or TCP/53 on any nameserver IP they are given.
Comment: Thanks. Are TCP port 53 and UDP port 53  two distinct ports?
Comment: Can you also answer my part 1?
Comment: I'm not really sure what the first part is asking, though one could certainly run a DNS or whatever server on some other TCP or UDP port, assuming the client systems were properly configured to connect to it at that non-standard port.
Comment: Thanks. Sorry for the confusion. I have clarified my part 1.
Comment: For part 1, I was asking if the relation between a port and a port number is like a network interface and an IP address, in that the port number of a port can be changed? Or is the relation more like a network interface and a MAC address, in that the MAC address of a network interface is almost never changed, more like an identity rather than an address?
Answer: A computer can have one or more IP addresses.
Some IP protocols, like ICMP, only need IP addresses to communicate. Others, like UDP and TCP, require that packets be addressed to a port as well as an IP address. Generally you have a program implementing a service listen on a well-known port so that other systems know how to contact it. An ssh server will, for example, listen on port 22/tcp:
$ netstat -a -t
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 *:ssh                   *:*                     LISTEN

$ netstat -a -t -n
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN

The netstat program will give symbolic names to port numbers, by looking in /etc/services, and a program such as sshd would call getservbyname("ssh","tcp") to convert a name to a port number.
If you listen on IP address 0.0.0.0, that means to listen on all of a system's IP addresses, and that's why netstat prints a *.
The ssh server doesn't have to listen on port 22. You can change its config file to listen on port 8022, say. As long as the remote user knows the port number, and any intervening firewalls allow traffic to port 8022, it'll work.
For hundreds of services around the world, the well-known port numbers are maintained in the Service Name and Transport Protocol Port Number Registry. It's a superset of your local system's /etc/services.
A socket is a communications endpoint. Before it can be used, it must be bound to an IP address, port number, and protocol. If it's using TCP, it must then be connected to another socket before packets can be exchanged. A server calls socket to create a socket, bind to bind it, and listen to listen for connections. A client uses socket and bind, then connect to connect to a server. (The call to bind is optional for a client; when connect is called, the system will allocate an unused port and pick an appropriate IP address to bind to the socket.)

sockets with TCP port 53 and UDP port 53 are distinct sockets

If a service can be offered on both TCP and UDP, it's customary for the port number to be the same in both protocols. In the above case, you'd probably have a single DNS server that creates two sockets, one listening on 0.0.0.0:53/tcp and the other listening on 0.0.0.0:53/udp.
Some older services were designed to run on only one protocol, and in those cases you may see two services using the same port number (but of course on different protocols). For example, 512/tcp is for rexec, but 512/udp is for biff.  Systems like this have completely different programs listening on the ports. rexecd listens on 512/tcp, and comsat listens on 512/udp.
Comment: Thanks. Is it correct to distinguish between a port and its port number, just like a network interface and its IP address or MAC address? My question is whether the port number of a port can be changed.
Comment: They're similar, but a port is conceptually more like a PCIe slot on your computer. Each has a number, but you don't get to arbitrarily choose the number; it's 1, 2, 3, etc. up to some maximum number. Your kernel will typically support 65535 ports for each protocol, numbered 1 through 65535.
Comment: do you mean the port number of a port is fixed and can't be changed?
Comment: Yes, it can't be changed.


Is it possible to manipulate with coordinate systems in geonodes?

Question: i want to multiply by 0 part of the velocity vector, that points from center of sphere1 to center of sphere2. So easiest way i can think of is to calculate velocity vector in new coordinate system where R1 vector is y or x, multuply y or x by 0 and than go back to global coordinates. But only way i can imagine it in current geonodes is to calculate angle btwn local and global X and than rotate the whole vector, manipulate it and then rotate it back. But it gets really hard when we go from 2 dimensions to 3 dimensions. Any ideas pls?
Comment: I'm not sure if I fully understand what you're talking about, but you could probably use a dot product to see if a vector is pointing in that direction and scale it accordingly.
Comment: i need to change specific part of the velocity vector so it does not point in the direction of another shpere.
https://postimg.cc/jwZnTkn2 here is the image
so, we have global X and Y, two points (black), velocity vector (light blue), C1 and C2 vectors (C1 points to another point, it is first part of velocity vector, C2 is second part of velocity vector). So i want to scale C1 of velocity vector by 0, and get V2 vector (orange one)
Comment: This is probably a https://en.wikipedia.org/wiki/XY_problem and what you really need is Vector Math: Reflect.
Answer:
i want to multiply by 0 part of the velocity vector, that points from center of sphere1 to center of sphere2.

The dot product of two normalized vectors is the projection of one vector onto the other (https://en.wikipedia.org/wiki/Dot_product#/media/File:Dot_Product.svg)-- the "shadow" cast from one vector onto the other, if you'd like.
Let's call the vector from one circle to the other circle the "proximity vector".  If we take the dot product of the normalized velocity and proximity vectors, and multiply that by the length of the velocity vector, we get the size of that shadow cast by one vector on the other.  If we then scale the normalized proximity vector by this "shadow size", we have the component of the velocity vector that lies along proximity vector; we can subtract it from the velocity vector to end up with a vector that points only orthogonally to the proximity vector. *

But only way i can imagine it in current geonodes is to calculate angle btwn local and global X and than rotate the whole vector, manipulate it and then rotate it back. But it gets really hard when we go from 2 dimensions to 3 dimensions.

This is a more complicated problem than I think you want to solve, and solving it probably (depending on how you look at what you're solving) involves calculating what you want to calculate, via the method I described above.
* Note: The way that I described this involves some unnecessary operations, but I'm presenting it as I am because I think it's a better way to ease into the thinking.  The length of the shadow is dot(normalize(proximity), velocity), but knowing that requires knowing more about the dot product than I've explained and it can wait.

Answer: Let me first try to Steelman your question:

This setup generates two balls and two arrows on the 2nd ball (called 'Sphere 2').
One, white arrow is just an arbitrary (random in this case) direction vector. The other, red arrow is the result of the operation you want.
I think the best way to explain what you want is: position a plane exactly between the two spheres, tangent to those spheres, then add a Sun aligned with the plane's normal (the Sun direction same as the direction from Sphere 2 to Sphere 1), and look at the shadow of the arrow - that's the direction the resulting vector should have:

(the red arrow is so dark because it's entirely in the shadow of the white arrow)
And so the question is, what should be the contents of the Meat custom group in the green frame, to achieve this:

Solution
Your solution works for 3D as well: rotate to be $z$-up, remove $z$ component, rotate back. It's just that you need Euler $xyz$ rotation rather than just a single angle. Here in order to ensure both balls touch, I position the 2nd ball by rotating the $<2, 0, 0>$ offset by a random Euler, so that Euler is ready to be used; normally you would start with a vector and need to calculate the Euler. The opposite of Vector Rotate node is Align Euler to Vector:

(same result as in Nathan's solution)

Vector Math: Reflect


Creeper Holes - Minecraft

Question: Please I need help with some creeper issues on my private survival server. I want creepers to be exactly normal but one thing. They can't blow up grass and dirt. Everything else they should be able to destroy except grass and dirt.
Comment: Vanilla servers doesn't provide such functionnality. I don't think anyone ever made a mod/plugin allowing such control on creeper explosions, it's mostly everything or nothing.
Comment: Sadly @Hybris95 is correct. There is no functionality for what you are requesting at the moment.
Answer: A little trick with command blocks would help in this case:
Setup:
<code>/scoreboard objectives add noFuse dummy
/scoreboard objectives add Teleport dummy
</code>
Clock:
<code>/execute @e[type=ArmorStand,score_Teleport_min=1] clone ~10 200 ~10 ~-10 190 ~-10 ~10 ~10 ~10 filtered normal minecraft:dirt
/execute @e[type=ArmorStand,score_Teleport_min=1] clone ~10 200 ~10 ~-10 190 ~-10 ~10 ~10 ~10 filtered normal minecraft:grass
/execute @e[type=ArmorStand,score_Teleport_min=1] fill ~10 200 ~10 ~-10 190 ~-10 minecraft:air
/kill @e[type=ArmorStand,score_Teleport_min=1]
/scoreboard players set @e[type=Creeper] noFuse 0
/scoreboard players set @e[type=Creeper] noFuse 1 {Fuse:0}
/execute @e[score_noFuse_min=1] clone ~10 ~10 ~10 ~-10 ~-10 ~-10 ~10 200 ~10
/execute @e[score_noFuse_min=1] summon ArmorStand ~ ~ ~ {CustomName:"Teleport",CustomNameVisible:0}
/scoreboard players set @e[type=ArmorStand] Teleport 0
/scoreboard players set @e[type=ArmorStand] Teleport 1 {CustomName:"Teleport"}
</code>
First it finds all creepers that are about to explode, then clones the area around it into the sky, then after it explodes the dirt and the grass will be cloned down and the area in the sky will be deleted.
Comment: This is very creative and clever.
Comment: BTW this will allow blocks behind the grass/dirt to be destroyed
Answer: Global Answer :
Vanilla servers doesn't provide such functionnality.I don't think anyone ever made a mod/plugin allowing such control on creeper explosions, it's mostly everything or nothing.
Multiplayer :
If you are searching for such kind of Plugin, WorldGuard provides similar functionalities, you just can't filter on specific block's IDs.
SinglePlayer :
As Gilbert V stated, you can use <code>/gamerule mobGriefing false</code>. Like with WorldGuard you can't filter on specific blocks also.
Comment: The mobGriefing gamerule isn't just singleplayer.
Comment: Did I said so ? I just pointed out a tool that can do it in Multiplayer never intended to be exhaustive.
Answer: There exists a server plugin called CreeperHeal which is useful for this. Creepers still destroy things with this plugin installed. However, the terrain will regenerate after a short period. Also useful against griefers.
Answer: <code>/gamerule mobGriefing false
</code>
End result: creepers damage players but not blocks. This may not be exactly it is the closest i can think of for what you are after.

Creeper Holes - Minecraft


What to do if we find on-topic questions elsewhere that would fit well here?

Question: I came across this question on Stack Overflow today. I think it's a good question for dsp.SE, but it's also on-topic on Stack Overflow. Is there a means to cross-list it on both sites, or should it just stay where it is? I don't want to flag it as off-topic there, because it really isn't, although it is also directly signal-processing-related.
Comment: That's why I asked; the question really straddles the line between DSP and SO, because his question was really more theoretical: "How can I modify the structure of the first-order IIR filter calculations to make it vectorizable?" The ARM NEON intrinsics part was really a side issue in my opinion.
Comment: The question is [here](http://dsp.stackexchange.com/questions/1075/arm-neon-simple-low-pass-filter-vectorization) now.
Comment: The question was migrated to DSP, but later moved back to SO because it asked about programming the filter in a specific language (vectorized ARM NEON Assembly).
Answer: I've deleted my previous answer, since I think it could've given the impression that this issue is settled, but I think a discussion on these type of questions is much needed.
I agreed with you yesterday that it is a good question for us, because if you remove the ARM NEON fluff, it's basically a theoretical question on vectorization, which could stand alone independent of the specific language details. However, I know nothing about ARM NEON, and just skipped that part when reading the question, and flagged it for migration here. phonon felt that it was primarily a programming question that should've never been migrated and I respect his judgement and he's probably right about that.
I have a suggestion though. For questions like these that have a good underlying theoretical answer, that's not immediately apparent from the way it's phrased (or a conceptual question hidden under 'gimme-the-codez' text), we can migrate it here to create a copy, and clear the migration history on both sites (clearing migration history means that it reverses it and is as if it never happened – like the Stack Overflow question that you linked above). Then edit the question here to make it more theoretical and fit our site better and flag answers that don't address the modified question.
Needless to say, this can't be done for every question and the flagger should be interested in leading the editing of the question to fit our site (without the editing part, it's bad to have two identical questions with identical answers on two sites). Perhaps you could also notify the other answerers that the scope has been changed and that they should either modify their answer or delete it (they don't lose anything, because whatever rep they gained on SO is intact). I've done this at times with a few questions, and it has worked out well for the OP who gets both his code answer and his conceptual question answered. So as far as this one goes, if you'll edit the current question to remove the programming aspect and make it theoretical, we can reopen it.
Comment: I think it should be ready now.


What are the different branches of Shaktism?

Question: There are many different sects in Hinduism,like Vaishnavism,Shaivaism and Shaktism.Some sects,like Vaishnavism and Shaivaism,have different branches like Gaudiya Vaishnavism,which glorifies Krishna and not Vishnu as the supreme lord, and Pasupata Shaivaism,which is the oldest school of Shaivaism which is followed by ascetics.Are there any branches/schools of Shaktism as well?
Answer: One of the major Tantrik scripture is called the VishnukrAntA. It has within itself several other major Tantik scriptures like Nila Tantram, Niruttara Tantram and many others.
Now, AFAIK, it's only in the Niruttara Tantram, that the Shakti Deities are classified into two groups- Sri Kula and KAli Kula.
Here are the relevant verses:

KAli tArA raktakAli bhuvana mahishamardini | TriputA tvaritA durgA
  vidyA prtyangirA tathA || KAlikulam smakhyAtam sri kulam cha parama |
  Sundari bhairavi bAlA bagala kamalApi cha || DhumAvati cha mAtangi
  vidyA swapnAvati priye | Madhumati mahAvidyA sri kulam paribhAshitam
  ||
..............
The ten Goddesses famous as being belonging to the KAli Kula (the
  family or group of KAli) are- KAli, TArA, RaktakAli, Bhuvaneswari,
  Mahishamardini, TriputA, TvaritA, DurgA, VidyA and PratyangirA. And
  the ten Goddesses who belong to the Sri Kula are- [TripurA] Sundari, [TripurA] Bhairavi, BAla [Tripura Sundari],
  Bagalamukhi, KamalA, DhumAvati, MAtangi, SwapnAvati, Madhumati and
  MahAvidya.
Niruttara Tantram Patala 1, Verses 6-8.

So, based on this there emerged two different sects. In the KAli Kula, the principle Deities are KAli, TArA, DurgA etc whereas in the Sri Kula they are  Goddess LalitA, TripurA Bhairavi, BAlA TripurA Sundari etc.
Comment: Raktakali, Rakshakali Dakshinakali are slight variations of Goddess Kali. Triputa, Tvarita are mentioned in some other Agamas too. But they are not that well known like few of the others. Kamala is the 10th mahavidya. She is also called the Tantrik Lakshmi. I don't think i have found any other references of Swapnavati etc apart from that in the given verses. Yes, all the 10 mahavidyas have respective stories of manifestations, arrival tithis etc. I am planning to post a Q-A on this topic but i could manage it till now..@KVickneshvara
Comment: Whoa are RaktakAli, TriputA, TvaritA, KamalA,  SwapnAvati, Madhumati and MahAvidya? Given that they are famous, they must have at least one back story each, right?
Comment: @KVickneshvara I have answered about Goddess Bagalamukhi here: https://hinduism.stackexchange.com/questions/19333/who-is-bagalamukhi/19367#19367
Answer: According to Wikipedia, Shaktism or Shaktidharma (Sanskrit: Śāktaṃ, शाक्तं; lit., "doctrine of power" or "doctrine of the Goddess") is a denomination of Hinduism that focuses worship upon Shakti or Devi – as the absolute, ultimate Godhead. Its two largest and most visible schools are :
1.Srikula (family of Sri), strongest in South India, the Srikula's best-known school is Srividya
The Srikula tradition (sampradaya) focuses worship on Devi in the form of the goddess Lalita-Tripura Sundari
2.Kalikula (family of Kali), which prevails in northern and eastern India. The main deities of Kalikula are Kali, Chandi and Durga.
The major difference between these two is Srividya largely views the Goddess as "benign [saumya] and beautiful [saundarya]" While in Kalikula's focus on "terrifying [ugra] and horrifying [ghora]" goddess forms such as Kali or Durga.
Comment: @KVickneshvara This answer is more or less correct.However many feels worship of Lalita mahatripurasundari is the supreme sadhana as all Gods are worshipped thereby.One can't worship Srichakra without worshipping the Pancha Devatas (Ganapaty,Shiva,Vishnu,Ambika and Surya) as they are like guarding deities.In Kali Kula Sri Durga is the supreme deity.
Comment: Thank you!However,could you give some examples of the "a nearly endless variety of beliefs and practices" as well?
Comment: @KVickneshvara to be honest, I had no idea about the endless practices etc. I just copy-pasted the info from Wikipedia. Also, I could not found any ref. to such thing on internet. Hence I am editing that part of my post!
Comment: You're encouraged to cite some scriptural sources also instead only wikipedia.
Comment: @Pandya Yes, I am aware of that. Its just that I could not found any for this case...and not sure if scriptures can say how many branches are there for Shaktism
Answer: Now to get into Shaktism is highly complicated.
Let's start from base and then climb to the apex.
There are only 2 ways to enter Shaktism, (as Bhakti has no seperate branch as in Vaishnavism)
1. Yog
2. Kriya
1. Yogic way- This path is devoid of any rituals or has minimal rituals. The whole concept here deals with realising Bhagwati with yog. It has two paths, Hatha yoga- The person be in a particular vow or position and realize devi & second Gyan Yoga- Know devi after cutting off from world and engross in tapa.
2. Kriya- This path involes extensive rituals. Thus called as Kriya. It has two ways again-
1. Vedic
2. Tantric
1. Vedic - The vedic acharans are more linked with gentle forms of Bhagwati Mahamaya. Various mantras are used from Suktams, and Upanishads etc. Actually idk much about vedic shakas. The sadhakas here ar called Vedacharis.
2. Tantra - The tantric branch is highly complex. And majority of Shaktas prefer tantric diksha.
So, tantra has again 5 major branches to deal wid-
A. Dakshinachar- This is the right hand path where Sauch (purity) is of utmost importance. Originally only those with Yagnopavit(Janeu/upnayan) are allowed into Dakshinachar. This is the most gentle achar of Shaktism.
B. Vamachar- The school of left handed path. Here panch makars r used thus being antagonist to Dakshinachar.
C. Samyachar- To say Samayachar has both the components from Vama and Dakshina marg. Samayacharis focus on internal worship just like yogic paths. Yet, since rituals too are important to them thus clubed under Kriya.
D. Kaulachar- This is a step ahead version of Vamachar.
E. Chinnachar- Extremely rare marg to see today. This achar is exclusively dedicated to Chinnamasta.
(Let's not forget, Aghori, Kapaliks too have their ways to worship devi but mostly they are Shaiva. Thus didn't mentioned them here in list)
Futher now there are various paths depending on the isht a person wants.      I will write as far as I know.
a.Vajrakula - This kula focuses on Tara the 2nd Mahavidya. Buddhism is fully flegged in Vajrakula. Whereas Hinduism has only a very little knowledge on Vajrakula or Tarakula. As, Hindu Vajrakulas only worship 8 murtis of Tara, while Vajrakula has all 28 forms of Tara with them.
b. Chinnachar - Thou it's an āchar yet, since it is exclusive to Chinnamasta, hence once again mentioned it.
c. Dhaumrakula- This deals with Dhumavati devi as the primary deity.
d. Kubjika kula- The esoteric devi Kubjika is the Adhishthatri of this Kula.
e. Kulesvari - This kula is most likely extinct by now.
f. Durgakula - This included Durga devi or Jaggadhatri as primordial deity. Now, it has merged into Kalikula.
g. Matrika Kula - This kula deals with 7/8/9 matrikas. Although now this too has merged into Kalikula.
h. Kalikula- Here the supreme devi is Mahakali. This is the school of Mahakali. Since now other kulas (Vajra, Chinna, Dhaumra, etc)are dwindling up, Kalikula now includes upasana padhati of Tara, Chinnamasta, Dhumavati, Baglamukhi amongst 10 mahavidyas. Thus distributing remaining 5 to Srikula.
i. Sri kula - This marg is completly dedicated to Lalitamba. Other major deities include Bhuvaneshwari, Bhairavi (she is Bala herself), Matangi & Kamala.
There are many such schools or branches.                                   To say precisely, each Mahavidya had once their own Kulas which are now lost. Even Laxmi devi and Saraswati too had their own Kulas. Which too have been merged into Sri & Kali kula.
It's sad to see how Kulesvari and Kubjika cults were lost from normal masses. Now Vajrakula too have dried up. And recently Chinnachar is under threat. Since, Chinnachar needs sadhaka of finest orders as the path of Chinnamasta is no calk walk. Thus the sadhakas of Chinnachar are seen in very remotely areas around Assam or interiors of Bengal.
But, to the best the practices from any āchar or Kula must never be leaked to any wrong person.
Incase anyone wanna be a Shakta,                1st step is figure up your isht devi,   2nd  think you what you want the Yog or kriya path?                                        3rd ask Gyana or Hatha in yog, or choose Vedic or Tantric if opted for Kriya!                                     4th if selected Tantric, which Āchar does your heart asks for.                 And thus you will fall in the best category to reach Paramba. Although all roads lead to Bhagwati but yet, everyone has to embark their own journey on their own selected paths.
(Ps- I think there was no need to cite referances here, as these are basic names of Kulas or branches of Shaktism.)
कालिकार्पणमास्तु ।
Answer: śrī matre namaḥ
shaktism is devided in kula-s, āchāra-s, sub-sects or sampraday.
there used to be 64 kula dedicated to many devi
some surviving right now are-
durgā kula - dedicated to durga bhagwati & is alive in uddisha.
kāli kula - dedicated to kalikāmbā, is very famous in north eastern india.
śrī kula - dedicated to para-śrī or lalita mahatripurasundari popular in southern india
vajra kula - dedicated to tārā is present in bengal and in tibet.
kāmākhya kula - dedicated to kāmākhya bhagwati and is present right now in kāmarupa.
chinna kula - dedicated to chinnamasta and is present in nepal.
list goes on and on and on.
based on āchara-s there are 7 main acharas that are -

सर्वेभ्यश्चोत्तमा वेदा वेदेभ्यो वैष्णवं परम् वैष्णवादुत्तमं शैवं
शैवाद्दक्षिणमुत्तमम् दक्षिणादुत्तमं वामं वामात् सिद्धान्तमुत्तमम्
सिद्धान्तादुत्तमं कौलं.
vedachara, vaishnavachara, shaivachara,
dakshinachara, vamachara, siddhantachara, kaulachara.

among them considering 3 as overall are samaya kaula and mishra.
samayachara is what was followed by ādi śankarācārya.
atma advaita para bhakti is what is followed by antaryāga.
kaulā has 2 parts uttara kaula and purva kaula, purva kaula has shiva as presiding deity and shakti as his potency, shakti is gaud and shiv is padhan, in uttara kaula shakti is pradhan and shiva is gaud, so-
purva kaula - shaiva
uttara kaula - shakta
krama is there for many devi-s but kula isn't.
in shri vidya there are 3 main sampraday
ananda bhairava --> kaula
dakshinamurthy --> samaya
hayagreeva --> dakshina


Mosfet for low load current

Question: I'm switching a 1mA load current that has 24V load voltage. The Control voltage is 5V and is driven from a microcontroller that can also source 24mA. Is it better to use an N Channel MOSFET or a NPN BJT Transistor?
Comment: What do you have handy? What are you more comfortable using? What's cheaper for you?
Comment: Does it depend on speed or cable capacitance or have inductive effect?  if not then either
Answer: You can use either since your design requirements are easy.   But I personally would use an NPN because of the much lower cost and robustness (no gate to zap accidentally).
It does cost an extra resistor for the base but resistors are cheap.

Mosfet for low load current


How can we reduce the power consumption of our iOS game?

Question: We just developed an iOS game and users have been complaining that it drains their battery power. It plays at 60 frames-per-second and uses a proprietary gaming engine (written in C#). May one of those be the issue or are there other common factors that should be investigated first?
Comment: Have you run your app through Instruments? There are several modes that allow you to focus on certain factors, but even if there are no apparent issues it's a good idea.
Answer: Apple have some guidelines on reducing power consumption in their iOS programming guide
Good place to get started on some tips.
Answer: Firstly, run the code through Instruments and see how it effects CPU usage (constant high CPU will drain the battery). Also, do you use any device features such as GPS or WIFI? These will drain the battery further.
Secondly, do you run any background processes when your app should suspend that might be eating away at battery?
You can keep track of any performance you enhance by checking device logs for power consumption, making a change and saving another log.
follow these instructions to accomplish this
Answer: There may be one simple answer, try running your game at 30, or maybe even as low as 24 FPS.  Is there any REAL reason you need to be running it SO fast???
I stated 24 by the way as it is "technically" the fastest your eyes (for the majority of human beings) can detect.
In video, we try to go higher because there are artifacts that can be seen from the recording process, but because games have generated scenes, generally you dont NEED to go higher than 24.
Answer: A good first step would be to reduce the frame-rate to 30 FPS.
For any reasonable game, 60 FPS is overkill. At some point, your eyes just cannot tell the difference, unless the frame-rate is skipping. That rate occurs at about 24-30 FPS, and that's why It's most used for videos & gaming.
I would caution you though, if you do have a real-time game (especially one based on reflexes), that you do your game logic on another thread. If you do not, you could have flaw that other games have, for example:
Call Of Duty: Modern Warfare 3 has a major flaw in it's engine design in that the fire rate that your gun shoots is determined solely by the frame rate of the game, and not by a background thread.
This makes certain weapons more dangerous than others, because at a frame rate of about 60 FPS, they have an integer amount of time per shot.
So with that said, just try reducing your framerate. That alone is probably what's eating most of the battery.


What is the purpose of 802.11 authentication?

Question: Why does client authenticate before associating with the AP. What does open system authentication even achieve. I fail get an accurate reason from my web searches.
Comment: Below answers are close. Due to a confusion I did re-ask the question and have accepted the answer here: https://networkengineering.stackexchange.com/questions/55790/why-do-we-have-authentication-before-association-in-802-11
Answer: In a wired network, you have a one-to-one mapping between the client device, the network cable, and the network (via a switch port).
In a wireless environment, it is possible (and indeed common) that multiple wireless networks exist in close proximity to each another, so you need a way of specifying which network your client device will connect to.  Open system authentication is the simplest method of doing this eg: specify the SSID of the network and your client will connect only to that network.
Answer: Unlike wires, where you can control who connects to what, wireless connections easily penetrate walls and property boundaries. In your network, you'd want to control who can connect.
Additionally, wirelessly transmitted signals can be intercepted everywhere in the vicinity - you'd want to encrypt the traffic to protect sensitive data.


How use Truffle Framework

Question: Anyone please help me to understand what is exactly Truffle & Ganache ?
How to install & use Truffle ?
Please reply who are know this.
Answer: truffle suite is framework for developing ethereum based smart contract and integrate it easily with front end. Ganache is tool available in truffle suite, which is used for smart contract development and deployment.Drizzle is another tool of truffle suite to build front-end for smart contract.
you can easily find the installation of truffle suite in internet, it varies based on the os you are using.
https://truffleframework.com/docs
Answer: Truffle: development and testing suite for smart contracts written in Solidity
Ganache: testrpc aka your local testnet that Truffle utilizes to test deployments (migrations) of your smart contracts so your testing suite has something to target with near immediate results (no 15s block times!)
Layman terms: your own private, local EVM blockchain
Drizzle: Frontend UI
Go here for documentation and tutorials: https://truffleframework.com/docs

How use Truffle Framework


How do I make my marriage to a non Muslim valid?

Question: I have found a Christian girl who I am dearly in love with. She is a prostitute. Even though she is not chaste, I really want to marry her however she doesn't want to convert to Islam. If we carry out all of the necessary conditions for a valid Islamic marriage, can she repent her sins without converting to Islam? Would this make the marriage valid?
Comment: Is this the Russian online escort that someone asked about a couple months ago?
Comment: Someone asked a similar question a few months ago, he had met a Russian online escort and was wondering how to go about an Islamic marriage without her converting.
Comment: what are you talking about?!
Answer: Allah (ﷻ) said,  والمحصنات من الذين أوتوا الكتاب من قبلكم إذا آتيتموهن أجورهن محصنين غير مسافحين ولا متخذي أخدان "And [lawful in marriage are] chaste women from among the believers and chaste women from among those who were given the Scripture before you, when you have given them their due compensation, desiring chastity, not unlawful sexual intercourse or taking [secret] lovers" (5:5).
This verse makes chastity a condition.
Thus in the scenario you described, the only thing making the potential marriage invalid is the fact that she is a prostitute. If she gives up prostitution entirely, repents and remains chaste thereafter.. then you may marry her and the marriage will be valid per Islam [since Islam allows marriage to women among the People of the Book].
So to make the marriage valid, she needs to repent and give up prostitution.
That said, some friendly advice: I would say to be wise and think about who you desire to marry. Because this person is going to be raising children and affecting their faith and actions, ultimately. Love can sprout with many different people, but not everyone with whom it spouts will take you towards Jannah.


Finding info about clan before joining it, such as war win/lose ratio

Question: In clash of clans what's the best way to get a sense of a clan before joining it? I know it says total wars won but without knowing the total wars or total wars lost this is useless. Is there a way to know the details of the wars before joining it? I've seen some clans boast about being Elder free but isn't this a bad thing?
Comment: The Elder thing is open to opinion. Perhaps just focus your question on the win/lose ratio, which is definitely answerable.
Comment: split this up in 2 questions next time :)
Comment: @Ellesedil can you elaborate? What is special about being an elder anyways or does it just mean the person has been in the clan a long time?
Comment: @Celeritas: That sounds like a great question to ask. I'm sure other new players joining clans could have that same question.
Comment: I personally don't care much about the titles. The only thing they really do is give some degree of control within the clan. Elders can accept/reject applicants if the clan is invite only and kick regular members. Co-leaders can do all what elders can do, plus start wars, change some clan settings, send clan mail and kick elders. As for win/lose ratio, there's no way to know unless the clan displays it in the clan short description (mine does :))
Answer: the clan can choose to not let anyone see the war win/lose ratio or they might have not done any wars yet to see their clan just hit view clan and also if a clan says free elder be carfull they could be a failing clan.
Answer: There is no chance to get the win/loss ratio
Comment: @Celeritas If you do that, you never see the whole log, plus since losses are not 'saved' somewhere (at least not visible to players), you won't know the number of losses a clan really has.
Comment: You can join a clan and then view the war log and if you don't like it, leave. Is there any down side to this? It's kind of wasting everyone's time by the game not letting you see the war log before joining :(
Answer: You cannot view their win/loss ratio. You can join the clan, look at recent wars, and make a decision. Related to being elderless, that's primarily opinion based. Elder means different things to different clans.
I'd suggest
1. Joining the clan and taking a look at their past wars
2. Check out the profiles of their leaders, look at their donation rates/clan war stars/any other information you think is important to you.
Unfortunately, Supercell has not provided very meaningful ways to scope out a clan before joining it.
Answer: There's no way to determine how good a clan is before you join it unless you are looking for specific things.
You can see where the clan is located. If you are from Australia and the Clan is based in China then it may not be the clan for you unless you can speak Chinese.
You can see how often the clan wars as well.
It terms of telling how well a clan does in war you can look at the players in the clan. A Clan that has a lot of rushed Town Halls don't usually have a great war record.
The best thing you can do is join the Clan and opt out. Watch how they war raid and communicate. The war ratio is not always a good indicator as to how well a clan wars consistently. For example, my clan just had a 5 loss streak because we had 2 Town Hall 10's and the 5 enemy clans all had 4 (why? I'd like to know too). Before that 5 loss streak we hadn't lost a war in 3 months.
Answer:
Is there a way to know the details of the wars before joining it?

War win ratio is sometimes seen in the clan's description, usually to show off their win streak and how awesome they are. Now even though you can't quite see the exact details of the clan, a very high level clan usually means they win.. a lot.
Clans with high-level players with a serious description and wanting good players for war also a sign that the clan is efficient in war. Clan level at least of 6 usually means a nice history behind them. Matching their number of wars won with their clan creation date (if seen) can also help a lot. Though you can't see all the details yet, with good players, lots of wins, a serious war attitude, and a high clan level usually means a very active, and successful war clan but it's a risk you gotta take.
Joining just to see the history is just a waste of time. Most clans with good histories are also invite only, so watch for those clans. Anyone can join type clans are usually desperate for members, not good war members. And waiting for the invite to be accepted can take a while...

I've seen some clans boast about being Elder free but isn't this a bad thing?

It depends. Elder is a good incentive sometimes if used wisely. If everyone is elder, there isn't much off a difference of all members. Having free elder also helps by letting clanmates invite valuable and/or needed players without lots of begging. Now if you say free co-leader then you got a really big issue here...
Answer: War clans isn't operational anymore but that was one way to see win loss record. As for being elder free that all depends on do they get elder for loyalty etc.
Answer: You can just check the War Log in order to view War info. (However, you can see it only if it has been set to Public by a Leader/Co-Leader) Also, check if members donate enough. This way you can tell whether a clan is worth joining, or not.
Answer: warclans.com can tell you their win/loss ratio


how to quickly dry out home made marshmallows?

Question: I just made home made marshmallows for a birthday party in 7 hrs. How do I dry them out quickly? I used Ina G. recipe, she suggests to sit overnight, but on line it says to sit 8 hrs to dry. I need to dry them sooner, can I put them in the fridge for how long? should I put them in a cold over? Help someone, please.
Comment: Welcome to Seasoned Advice! Have you dusted or rolled them in powdered sugar?
Comment: Can't you use a table fan ?
Answer: If the marshmallow batter is set/firm (not runny) and already cut into pieces, simply combine equal parts cornstarch and powdered/confectioners sugar and toss or roll the pieces in the mixture. Tap or shake off excess powder and you should be fine!


Difficulty understanding the faster multiplication hardware

Question: This is a picture of faster multiplication hardware taken from Computer Organization and Design (5th Edition). I'm having some difficulty understanding it. I was trying to simulate this for a test multiplication of : 1011 x 101. Firstly, P0 is simply the LSB of the (Mplier0 * Mcand) which gives P0 = 1 The two operands of the upper rightmost adder would be then, 1011 (Mplier0 * Mcand) and 0000 (Mplier1 * Mcand) which would produce the result 1011 with P1 = 1. This 1011 would then be one of the inputs of the second stage adder. The other input of the second stage/level adder would come from the upper 2nd rightmost adder. Which gives 1011 (Mplier2 * Mcand) + 0000 (Mplier3 * Mcand) = 1011. So the two inputs of the second stage adder are both 1011. Finally the output of this second stage adder will be 1011 + 1011 = 10110. The penultimate result is 1011011. But the correct answer is 110111. What am I doing wrong here?
Comment: You're focusing too much on the details. Instead of looking at the diagram, try coming up with the circuit on your own. It's more important to understand the idea than the exact implementation details.
Comment: I've looked at it for a long time. Tried to come up with my own implementation but failed. Any help would be appreciated. @YuvalFilmus
Comment: Another question came to my mind that do the adders need to be wider as we go down ? Because my product is 64 bits but all the adders are 32 bits. Wouldn't it cause some problems?
Comment: Okay, I seem to have understood it. The LSB goes to ``P_n`` at each step and the rest goes to adder input.
Answer: You want to multiply x by y, where both are 32 bit numbers.
The result is the sum of 32 numbers. The first number is x if bit #31 of y is 1, and 0 if bit #31 of y is 0. This number is shifted by 31 bits. The second number is x if bit #30 of y is 1, and 0 if bit #30 of y is 0. This number is shifted by 30 bits. And so on. The last number is x if bit #0 of y is 1, and 0 if bit #0 of y is 0. This number is shifted by 0 bits.
So you have 32 numbers to add. You use 16 adders in parallel to add the first and second, the third and fourth, the fifth and sixth number and so on. You get sixteen 34 bit results. Next you use 8 adders in parallel to each add two of these sums. Then 4 adders in parallel, then 2 adders in parallel, then one adder to get the final result.
Obviously you figure out how big each result can be, and where you would be adding zeroes (which obviously don't need adding). In total you need 31 adders, five levels deep, so the delay for the multiplier is about five times that of a 32 bit adder.
(BTW. There are methods that can get the result faster and I think with less hardware).
Comment: I've been thinking about this for quite a while, and found out the left part of the diagram is incorrect, to fix it we should use wider adders. For more information, see: [Parallel multiplication hardware](https://electronics.stackexchange.com/a/56518/218779)


Is there a good ActiveX/COM component to "print" to PDF?

Question: Clutching at straws here, I think I remember seeing a solution to this somewhere but can't find it now.
The issue is that I need a Windows application (not .Net) to be able to generate PDFs.  The "standard" solution is to use something like PDF995 or CutePDF which create a dummy printer that your application can then print to and it is redirected to a PDF file.  The problem is that to control those printers requires updating INI files or registry keys and that is error prone and often runs into concurrency problems.
Building the PDF file programmatically isn't an option, it needs to be able to take the output that would normally be sent to a printer, or possibly convert directly from an Excel file.
Ideally, I'd just pass the Excel file to a COM/ActiveX object and it would write to a file I specify.  Next best option would be for it to create a separate printer per print job or have some reasonable way of guaranteeing the filename I give will have the document I print.
This Excel to PDF Batch converter might do the trick as at least it has a command line mode, has anyone tried that?  It would only solve the problem for Excel files though.
So, is there a better solution?
(As a side note, for Visual FoxPro reports XFRX works really well, it converts the report directly to a PDF without needing a printer driver.)
Answer: You might want to look at BullZip (google it because I cannot add hyperlinks yet). We recently had Jody Meyer present this tool at the Detroit Area Fox User Group (previously shown at the Grand Rapids Area Fox User Group too). It was a great session.
She showed how to use the COM object to automate a ton of the BullZip features including the name of the file and properties like author and keywords. Watermarks are a snap too. It is simple and straightforward and her example was rock solid. Tons of features already done for you so you can simply re-engineer the demo form.
You can download it on the DAFUG Web site, in the downloads folder. File name is BullZipDemo.zip (google Detroit Area Fox User Group) and add the folder and filename.
Rick
VFP MVP
Comment: Thanks Rick, found this: http://www.bullzip.com/products/pdf/info.php
Documentation here http://www.biopdf.com/guide/examples/batch_printing/ suggests that they handle the concurrency issue by having a "one shot" runonce.ini settings file, so looks like it might be worth a try.
Answer: For this scenario I would recommend Amyuni PDF Converter. It provides a Microsoft Certified PDF Printer and ActiveX/.Net controls to communicate with it. Concurrency issues can be avoided by using these controls.
Disclaimer: I am part of the development team of this product.


Is it harmful to mix Hydrogen Peroxide with oven cleaning spray?

Question: My mother recently stumbled upon this mix when she was trying to remove stains from some laundry. When just the peroxide didn't work, she sprayed on some Easy Off, and the stain disappeared. Now she uses this method regularly, and I'm worried that it might be toxic or something. I just want to make sure she isn't poisoning herself.
Comment: It's good to note that all chemicals can be toxic or harmful. It's not a good idea to go mixing reactive chemicals like those , I'm not sure what easy off is but oven cleaners normally pretty reactive. Sounds like a bit of overkill would probly damage the clothes or washing machine.
Comment: I'd say to use things that are designed to go in the washing machine,on clothes and not harmful to skin that is not corrosive like the oven cleaner!.
Comment: I wonder if this is just used on white cottons. I'd expect Easy Off to be KOH or NaOH, really quite nasty stuff. When I was working for IBM in a manufacturing plant I was always amused by the thought of trying to get  such oven cleaning approved on the production line. The operator would have been in a bubble suit! You never wanted to ask if a process procedure was safe. ;-)
Answer: Chemically, we are talking about mixing hydrogen peroxide with sodium hydroxide. They will react to form sodium hydroperoxide, but the latter is not as good an oxidizing agent as hydrogen peroxide, and a weaker base than sodium hydroxide. Probably the added base helps to dissolve some components of the stain. I don't see this as risky, especially if it is on a small scale (spraying laundry), and uses 3% peroxide, rather than mixing them in bulk. Note: With hydrogen peroxide, you have to watch out because some metal ions catalyze its decomposition to oxygen and water.
Comment: Sodium hydroperoxide is a better nucleophile than sodium hydroxide which will facilitate the stain removal.
Answer: I accidentally stumbled across this question. I once had a coworker clean a toilet with bleach and 409. The tragedy was he knew better and yet no one was injured. The man was smart but his thin stress management had a way of making things less clear headed when making everyday decisions.
I had to do OSHA 10 and OSHA 30 for work many years later. I realize such training is not much but it is something that made me want to check carefully as I make decisions. I have watched different people not check or measure twice to cut once or some such decision making process.
That said, in my opinion oven cleaners are harcore effective. I can't say what the oven cleaner in question was made of because I wasn't there. I want to comment on what @iad22agp wrote because it gave me the chills.
If a cleaner made with lye or sodium hydroxide is used or within splashing distance it sounds like extra care should be made to keep hydrogen peroxide very far away. I am not a chemist but I can read MSDS cautionary info. According to the California Fatality Assessment and Control Evaluation report below, posted by the CDC/NIOSH, a "mixture of sodium hydroxide and hydrogen peroxide produces a strong oxidizer called sodium peroxide and can result in an exothermic mist from the onset of high temperatures and heat from the decomposition of incompatible mixtures causing a severe thermal hazard."
California FACE Report #09CA004: A Chemist Dies from Burns Caused by Mixing Chemicals (pdf)
NIOSH: California Case Report: 09CA004 (html)
The man who died must have experienced a horror show as he passed... I realize the FACE report is not an MSDS for either product but it seems important to consider when cleaning with chemicals in the way described by the OP's question. I realize that industrial chemicals are more dangerous than domestic cleaning products but being extra careful beats dying every time.
Comment: To be fair though, the container in that report was $\pu{50\%}\ \ce{H2O2}$ while household cleaners will typically be $\pu{3\%}$.
Comment: Indeed, "I realize industrial chemicals are more dangerous."


Implementation of NAND gate

Question: The image below shows a extremely simplified circuit diagram. I do understand the logic behind that. However, the other image(below) is the one i dont understand. It shows a circuit diagram implementing the NAND gate. I do understant how the NAND gates works. However i dont understand the circuit on the left of the image. The truth table shows the correct output of a NAND gate, however, based on the circuit diagram on the left of the image, if A and B is 0 shouldnt the output for Y be 0 as well. I dont understand the symbol beside the Alphabets as well. I dont know how the current in the circuit diagram is flowing as well. Would anyone care to explain how this works? Thank you.
Comment: Note that the little circles on some of the gates implies inversion, i.e. the transistor is OFF when its input is '1' and ON when '0'.
Comment: The symbols next to the letters A and B represent transistors.
Comment: Hey thanks for the reply. Yeah i just figured that out. But how about the values in the truth table? Can you explain how that works?
Comment: @user859385 The truth table is just a shorter, prettier way of saying "When A is 0 and B is 0, Y should be 1. When A is 0 and B is 1, Y should be 1." and so on. (this particular one is also colour-coded with blue for inputs and yellow for outputs)
Answer: In VLSI the transistors with the little circle on their gates are the p-channel transistors while the ones without it are the n-channel.
When n-channel transistor gate is at the GND level (and source is also at GND) it's in the cutoff state (OFF). There is no conduction between drain and source. When it's at 3.3V the current flows between drain and source causing the drain to be also at GND (ON).
When p-channel transistor gate is at the VDD (3.3V in your case) (and source is also at VDD) it's in the cutoff state (OFF). There is no conduction between drain and source. When it's at GND the current flows between drain and source causing the drain to be also at VDD (ON).
In the truth table assume that 0 = GND and 1 = VDD (+3.3V).
Now figure out in what state is each of the four transistor for all 4 combinations of the inputs A and B. This will help you understand the Y output levels.
For AB=00 both of the n-channel transistors are OFF and both p-channels transistors are ON causing Y=VDD (1)
For AB=01 or 10 only one the n-channel transistors is OFF and only one of the p-channel transistors is ON which still causes Y=VDD (1)
For AB=11 both the n-channel transistors is ON and both of the p-channel transistors are OFF causing Y=GND (0)
Answer: Here is how the circuit works for each of the cases shown in the truth table for a NAND gate:

Note that for either or both inputs = 0 (low), the output is 1 (high, or 3.3v).  This is because the top two parallel transistors are inverting, so if the input(s) are low, the corresponding transistor(s) will be on, connecting 3.3v to the output.  Meanwhile one or both of the series transistors will be off, so ground is inhibited from being connected to the output.  This follows the NAND rule, if either (or both) inputs are 0, the output is 1.
However if both inputs are high (1, or 3.3v), then the two series transistors are both on, connecting the output to ground (low, or 0v).  3.3v is inhibited from being connected to the output since both of the parallel transistors will be off since their inverting inputs are high.  This corresponds to the NAND rule, if both inputs are 1, the output is 0.
Answer: I think your 'extremely simplified' diagram is what's causing the confusion. That's not a CMOS inverter, it's a pmos inverter. You'll notice that it never drives the signal to ground, which is an issue when we're talking about devices with very small current drain.
The second diagram, of then nand gate, is cmos. That's complimentary metal oxide semiconductor. It has a pmos circuit (that's the transistors with the circle on the gate) that's connected between v and the output, and the logical opposite nmos circuit connected between the output and 0. The point being that the circuit can be driven high or low without the use of energy wasting pull-up resistors.
Basically, the top devices are pmos transistors, they are closed when the input is 0 and open when it's 1 (thus the bubble on the gate), the devices below are the opposite. If we take the case of A=B=0, we see that both of the top devices are closed, and the bottom devices are open, So the output becomes 1

Implementation of NAND gate


What is this insect with a funny color pattern?

Question: What is this insect? Does she do any harm?
Comment: 'Harm' in what sense? Hurting people, damaging plants, causing mild irritation?
Answer: This is a stink bug, possibly Southern Green Stink Bug (Nezara viridula); for reference see Field Guide to Stink Bugs  thumbnail Sec1:2 for photo close to this one. Since it is listed in this guide it is an insect that can do harm, however I have seen stink bugs feeding on Colorado Potato Beetle larvae so it is all a matter of context. Do your own reading now that you have a starter.
Answer: It is certainly Nezara viridula, and it's a 5th instar version - it will turn brown for winter. This one is native to the UK and Europe. These are interesting insects because their appearance changes quite dramatically over time, see images in this Wikipedia article.
Known as stink bugs in the USA (although the true 'stink bug' is actually a different shield bug, [Halymorpha halys), but commonly called shield bugs in the UK, they are sometimes parasitized by a particular wasp. They are generally only a pest on agricultural crops and don't seem to cause much damage in mainly decorative home gardens, though if you grow a lot of legumes, they may be a problem.
Comment: You may also want to mention exactly why Americans call them stink bugs. From Wikipedia: _"The stink bug derives its name from an unpleasant scent from a glandular substance released from pores in the thorax when disturbed. The chemicals involved include aldehydes, making the smell similar to that of coriander. In some species, the liquid contains cyanide compounds and a rancid almond scent, used to protect themselves and discourage predators."_
Comment: @Pharap - I did not mention the 'stink' and its explanation because I suspect the OP is in Europe somewhere - Nezara viridula is native to Europe and the UK, and is not known to make a stink, as you put it. The one that does is the Brown Marmorated  Stink Bug (Halymorpha halys) which is the primary one causing that sort of problem in parts of the States. Luckily, so far, that particular shield bug has not made it to the UK in any numbers - its probably only a matter of time, given climate change, but so far, only 2 have been recorded which did not survive in the UK.


Martingale under risk neutral probability

Question: I have a question to prove martingale under risk-neutral measure:
Question
Consider a discrete time process $S$, which at time $n \in \mathbb{N}$ has value $S_n = S_{0}\prod_{j=1}^{n}Z_j$, $S_0>0$ and $Z_j$ a sequence of independent and identically distributed random variables to either 1.15 or 0.85. Assume a zero risk free rate of rate.
Show that under the risk neutral martingale measure $\mathbb{\hat{P}}$ the process $S_n$ is a martingale.
My thoughts

I do understand that under the risk neutral measure $\mathbb{\hat{P}}$, which is that $e^{-rt}C_t = \mathbb{\hat{E}}[e^{-rt}C_T|\mathbb{F}_t]$.
I understand that 1 - period $\mathbb{\hat{P}}$ is that:

$\mathbb{\hat{P}}_u = \frac{1-0.85}{1.15-0.85}=0.5$, and so is $\mathbb{\hat{P}}_d$ = 0.5.

I think I seek to prove the martingale property of $S_n$,but I am not sure how is that related to the $\mathbb{\hat{P}}$ if I just want to prove that:

$\mathbb{E}|S_n|< \infty$
$\mathbb{E}[S_{n+1}|\mathbb{F}_t]=S_n$
Answer: You already have it. Risk neutral measure is one where tosses are still independent but each individual toss has probability of 0.5 up or down.
Say you're at step n, with $S_{n}$ known.
$E(S_{n+1}|F_{n})=S_{n}*(0.5*1.15+0.5*0.85)=S_{n}$
and unconditional expectation is also finite using tower law as it equals $S0$.
Comment: Oh that is super helpful! I didn't even realise how close I was !


Running unmanaged C++ function on client-side ASP .Net C#

Question: Some functions in a legacy C++ Win32 application needs to be run on client-side in a new ASP .NET C# MVC Web application. Functions such as accessing client side shared memory.
I was wondering what is the best way to do this?
Thanks
Answer: One way to do this is by implementing an ActiveX component, although I don't think anyone would recommend it.  There is really no other way to download/install client-side native code via a web site.  Note that this limits you to web browsers that support ActiveX controls, and it will only run on the platform for which the native code is compiled/linked.
Another possibility is to get the user to install a native service on the client side, and then access it via some sort of IPC interface.


Does being the target of a DoS attack imply a vulnerability of my operating system?

Question: Does being the target of a denial of service (DoS) attack imply a vulnerability of my operating system?
Comment: it depends on what DOS it is?
Answer: In a word, "No".
The aim of a denial of service attack is to slow down or block the attacked system.
Think of it as someone calling your phone over and over and over again.  Regardless of whether you answer/hang up or just let it ring... other (legitimate) people trying to reach you will get a "busy" signal.
The person calling you over and over again is essentially using a denial of service attack against you.
Your servers are not necessarily vulnerable... just like your phone isn't vulnerable... its just all the bandwidth (or service) is being used up so that others can't use it.
Comment: A nice explanation. +1
Comment: This answer demonstrates a misunderstanding of what a Denial of Service attack can consist of - it's not just "a botnet sending a flood of requests."  Many vulnerabilities are classified as DoS-related; if you have a server application which crashes if sent a malformed request, that's a DoS vulnerability.
Answer: All a DoS attack is is a bunch of people (or a botnet) going to your site at the same time. It's like having lots of people simply go to it in a browser and keep hitting refresh until the site goes down.
Sometimes a vulnerability makes the bad guys' job easier (see Slowloris, for example), but that isn't the reason for which you were DoSed.
Answer: If the denial of service attack is against your network access, then no. Your connection is simply being overwhelmed.
If the denial of service is something related to an internal system...i.e., your memory/resources/processor is being overwhelmed (and it's not from processing network-bound I/O) then it could mean you have a user or internal login taking advantage of an issue with your software.
Without knowing the kind of DoS you're referring to it's tough to say. But if it's a typical kind of DoS, it's just your connection being overwhelmed and you'd only be able to stop it with working with your upstream provider to see what can be done with firewalls and routing tables to redirect/drop traffic before it saturates your connection.
Answer: Not necessarily, it just means that you're one or more of the following:

Not well liked by someone or someones
Unlucky to be the target of some group of jackasses
A competitor to some entity that wants to cause you grief
Somewhat screwed

More often than not it's not the fault of the OS and there is frequently not much you can (easily) do about it other than to craft some clever blocking solutions.
Comment: Valid answer but not very informative. Reason for DoS is irrelevant.


What is the easiest way to defeat two Hewdraw heads at once?

Question: To unlock a panel, I need to defeat two of the Hewdraw heads at once on any intensity. I have tried a few times already, and it seems that wearing two heads down and using an ultimate attack doesn't defeat them. Has anyone done this yet, or do you have an idea, weapon type I should use or strategy to do this?
Answer: I played the level on 0.0 difficulty. I used a Knuckle Staff (Most staves will probably do the trick though), then I just fired off both special attack orbs once he was targetable.
Once I used the attacks, it knocked both heads off. Not too hard at 0.0 difficulty.
Comment: All staffs have identical special attacks (including damage). This also applies to other weapon types, the only difference depends on what weapon type you're using.
Answer: On 0.0 intensity, use any club or staff weapon's special (power) attack by tapping the one of the two blue orbs at the bottom touchscreen (they regenerate after use).
This attack will damage all three heads.
Three or so should be enough. You can hit each head with a charged attack and then use two special attacks.
Comment: Any specific club recommendations? I've got a Capricorn, Atlas, and Earthmaul here, and none seem to do a particularly good job hitting two at once.
Comment: I tried using the Earthmaul Club for it. It has a wide attack, but you have to do it perfectly to do it. I just ended up using a feather for that panel.
Comment: By "special attack" I meant the Blue Orbs that clear the entire screen in Aerial Missions.
Comment: I thought his answer was good. ok not the best description but the answer above it was less accurate.
Answer: Wow. I just played the level, and found out that when you wait long enough, Lady Palutena says she is charging an attack and Pit says he can defeat the three heads himself. But if you wait longer, she will fire the shot and destroy all three heads at once!
Comment: Actually, I've tried that already, but it didn't work. Sorry...


Use different google account for in app purchases?

Question: so I'm signed into an app (pokemon go) with my primary google account. However I have credit on my secondary account that I want to use to buy some in app purchases. It won't let me do this and only gives me options to pay using the first account, this makes sense but its quite annoying. Is there any work around?
Answer: Figured it out. I just uninstalled the app, logged into my second account on my pc on the play store website. Then I installed it from the website using the seconds account. After that I logged into the pokemon app using my first google account then i was able to spend the credit from my second account.
Comment: The best solution ever!
Thanks a lot you saved my day!
Answer: Once you are logged into an account, you have to use that account. It is the way it "remembers" or saves progress. What you could do if you had say, 20 bucks on your other account. Send gift credits to the account you want to use. I think the increments are in 5 only though so it may hinder you from adding more. I hope this helps.


Why cannot Operand forwarding remove all RAW hazards?

Question: I read a statement in the textbook that : Operand Forwarding cannot remove all RAW Hazards in Pipelined Processor but am unable to conceptualize that in my brain. Can you please explain it with an example where Operand Forwarding will not be able to remove RAW Hazard .
Comment: Welcome to COMPUTER**SCIENCE** @SE. `a statement in the textbook` Please identify the book and indicate where to find that statement - there might be more than one definition what exactly *Operand Forwarding* means.
Answer: Sure!
And I can assure that is a fairly good question, if you are not able to see all the combinations.
See, operand forwarding can indeed remove all RAW hazards inside CPU but it is helpless when not all execution inside the CPU.
What I mean is all the RAW hazard scenarios, that we can write involving REGISTERS only and execution is some ALU operation, operand forwarding can escape the hazard.
like:
r1 <- r2 + r3            : I1
r4 <- r1 - r3            : I2
r1 is being calculated in ALU for I1, while I2 needs to load r1 as operand for ALU. Here the trick is even though you load the operands of ALU for execution, bt ALU will first execute I1 and then I2 in that order. So, even though r1 is not ready at the assigned time for operand fetch phase of I2, but it will be available before ALU starts execution of I2, and thus taking the benefit of same fact:

CPU notes that I2 is wanting the ALU execution output as an operand.
So, CPU saves this information as setting a bit inside the circuitry. And allowing I2 to proceed with "OPERAND FETCH PHASE" while skipping fetch of I2.

(Fetch of I2 is actually done, when CPU sees the RAW and sets the bit, but that's just assurance of fetch done, NOT THE ACTUAL FETCH)
THIS IS OPERAND FORWADING!
Now as soon as ALU computes the value, as the bit of oprand forwarding is 1, it transfers the contents of ALU output to the ALU operand.
(NOW THE GUARANTEE HAS BEEN COMPLETE, AND r1 for I2 has been fetched).
But observe, the write to r1 by I1 may be not done yet and in next cycles this be done. But I2 might be in ALU execution phase at this cycle.
So, as the FUTURE OPERAND(r1) is inside CPU and ALU being sequential, we could solve RAW.
But the problem is with LOAD/STORE involved in RAW.
load r1, Address1        : I1
r3 <- r1 + r2            : I2
Now the ALU for I2 can't get r1 before complete I1 is executed and r1 has been really written into.
So, this time "OPERAND FETCH PHASE" of I2 will have stall and can't proceed.
Hope this helps.


Why are the coordinates of origin $(0,0)$

Question:
Why are the coordinates of origin $\left(0,0\right)$?

I mean why these are not $(1,1)$;$(1,2)$ or anything else?  What is special about $(0,0)$? Is this is just to ease the calculation?
Comment: In many contexts, yes, it's just for ease of calculation. The word _origin_ specifically means "The point with the coordinates $(0,0)$", but it's only convenience that makes the point special. Once you get a bit further on, though, it is the only single point in the plane that is a vector space all by itself, so at that point (heh) it becomes something more.
Comment: Basically, yes. The origin is completely arbitrary, so if you are allowed to choose, why not choose the easiest to work with?
Comment: The xy plane has 4 quadrants. By choosing (0,0) as its center, each quadrant becomes unique in terms of what the signs of the x and y coordinates are going to be. But it does not always have to be (0,0). Think of a logarithmic or exponential scale...
Comment: all lines $y=ax$ go through (0,0)
Comment: The point with coordinates $(0,0)$ is called the *origin* of the coordinate plane. There is nothing more to it.
Answer: It's useful to have a point of reference in the coordinate plane -- something from which you can say "that point is way off in the $+x$ direction," for instance -- and someone decided to call this "the origin."
But as for choosing its coordinates: any point CAN  work as an origin, as you observe.
The advantage to using $(0,0)$ is that it's easy to remember, because $0$ is a special number in the real number system (it's the additive identity, and has the property that $c \cdot 0 = 0$ for any $c$).
When you start to talk about displacements --- the amount you need to add to one point to get to another point --- it turns out that these, too, are represented by pairs of numbers, and there's a natural inclination to treat these number-pairs (called "vectors") as if they were the same as points (which are also represented by pairs of numbers). But for displacements, the displacement by $(0,0)$ is very special: it doesn't move anything at all. So the vector $(0,0)$ is special, and that gives yet another reason for saying that the point $(0,0)$ is special --- it's the one corresponding to the special vector.
If you really want to go a little further in pursuing this question, Hartshorne's Projective Geometry book is a treasure: it starts from geometric axioms for affine and projective planes and goes through the whole process of establishing coordinates on each; seeing that helps you understand what are the arbitrary choices and what are not.
Answer: $\newcommand{\Reals}{\mathbf{R}}$There's "hidden infrastructure" lurking in the question. To flesh out Arthur's comment: A Euclidean plane $E$ has no distinguished point. Cartesian coordinates with origin $O$ furnish a "dictionary" between points of $E$ and ordered pairs of real numbers.
In this dictionary, a point $X$ of $E$ may be viewed as the arrow with its tail at $O$ and its tip at $X$, in which case:

The operation of forming the parallelogram with three vertices given by $O$, $X = (x_{1}, x_{2})$, and $Y = (y_{1}, y_{2})$ corresponds to adding Cartesian coordinates, obtaining the fourth vertex
$$
X + Y = (x_{1} + y_{1}, x_{2} + y_{2}).
$$
The operation of homothety by a factor $c$ about the origin $O$ corresponds to scalar multiplication:
$$
cX = (cx_{1}, cx_{2}).
$$

With these operations of addition and scalar multiplication, the plane becomes a vector space. There is precisely one distinguished point in a vector space, its "zero vector", the additive element for vector addition.
If arithmetic operations on ordered pairs are to have the "expected" geometric meanings, the origin must have coordinates $(0, 0)$.
Answer: It is defined as such. A point from which the axes extend indefinitely in both the directions. You can always shift the origin if you want. Also, $\left(0,0\right)$ has it's own benefits while dealing with many situations like vectors, complex, dilation, etc.
Answer: I presume we're talking about (rectangular) Cartesian coordinates in the plane. Because, say, in polar coordinates it's not necessarily true.
I would say that from the planar geometry point of view, this is by so by definition. As others have said, there's no special point in the plane. But to set up a (rectangular) Cartesian coordinate system, we have to make some choices and some definitions. We pick a point $O$ to serve as the origin. We pick two mutually perpendicular lines through this point to serve as the axes. Then we define the $x$-coordinate of a point $P$ to be the distance from the origin $O$ to the perpendicular projection of $P$ onto the horizontal axis; similar for the $y$-coordinate. Apply this definition to the origin $O$ itself, and you get $(0,0)$.
Of course, other branches of mathematics offer different points of view and other insights...


Is it possible to learn Hebrew or Greek without a teacher or an online course?

Question: My first is a latin-based language, and I know just the latin script, I have no experience writing in cyrilic script, greek script, and hebrew script. Is it possible to learn Hebrew or Greek from books and internet without taking a course and without a teacher?
Comment: Not your main question, but I highly suggest learning the Greek alphabet before the Cyrillic. You'll get a lot of Cyrillic letters "for free" that way. Check out the equivalents of Roman D, L, P, and R.
Answer: I learned the Hebrew alphabet in 2017 from books and an app that would prompt me to write a certain letter and grade me on my handwriting. I started learning the actual language the next month and was writing full sentences shortly after that. I am now having conversations in Modern Hebrew with native speakers, having never taken a live, instructor-led course.
Self-learning an alphabet is possible, and not that hard either. I probably spent no more than 1-2 hours a day learning the alphabet for about two or three weeks.
Now, I would strongly recommend that you not tackle three writing systems at once! Identify the language you want to learn and then learn its script. If you want to learn Russian, go learn the Cyrillic alphabet and the language! If you are looking for Greek, you know what to do. If you want to learn Thai, stop reading this answer and go get a book or an app!
Comment: I think you mean not tackle them **at the same time** or together....
Comment: @Lambie yes, that's exactly what I mean.


Engine Transmission

Question: I've been having a problem recently, as I push the gas pedal my car moves super slow. It won't go faster then 10 to 15 mphs. As I drive it feels like the gears are not catching
Comment: So the engine is gaining RPMs (revving higher), but the vehicle is not moving very fast?
Comment: The car will drive for about 2 mins then the gas will delay when u push it. I'm forced to turn off the car and turn it back on. Then it repeats right after.
Comment: Hoping to clarify: The engine bogs when you press the gas pedal after 2 minutes unless you stop/restart engine? Or does the engine speed up, but the car doesn't go? What year is your car? We need some more information here to even start to help you answer the question.
Comment: Model Year, engine size, type of transmission? Any warning lights on? And finally more details, it's going to be difficult to give you a good answer as the question is currently asked?
Answer: There's a couple of scenarios that come to mind. Originally, I was going to write this as a comment, but it would simply be too much text. Others, please feel free to give reasons why any of these isn't the answer.
Clutch is Failing (manual trans only)
Generally, when your clutch fails, it only catches partially. Even if you give it a whole lot of gas, it's not transferring the torque to the drive shaft entirely. Generally, this will apply whether your car is hot or cold, so the fact that your car's behavior changes after two minutes may mean that this isn't the cause.

Exhaust is Leaking Severely/No Backpressure
I've seen a loss of horsepower when the downpipe had a major hole or was ripped off entirely. This generally makes for a very loud car, that screams but doesn't go anywhere quickly at all. If your car's exhaust is normal volume, you can likely rule this out.

Cylinder misfire
I've seen a severe loss of horsepower occur when one of the cylinders isn't firing smoothly. I've even seen this happen where the car will idle smoothly, but as soon as load is put on the engine (driving more than 10 mph), the engine operates down a cylinder. This was a accompanied by a blinking Check Engine light on my 2001 Jetta.
Note: A blinking check engine light is usually a Very Bad Thing, and (on VW's, at least) comes on when you're doing something that is potentially damaging the car.
Comment: A clogged catalytic converter is another exhaust problem that can choke off the power.
Answer: It sounds like your car could be in "limp"-mode. If the car detects some critical issues it can go to a mode where the power is drastically reduced to be able to just get it to the garage. Certain car models can do this also if the brake lights don't work etc.
You should have the error codes read to check what is going on. A local garage or dealership can do this for you.
Comment: Everything still works it's just the car dosent acceleratemail once u hit the gas
Comment: The problem might not be apparent without getting the error codes read, sometimes not even a CEL/MIL turns on and the car still goes to limp mode, depends a lot on the manufacturer implementation.

Engine Transmission


iOS Color Picker User Experience

Question: I'm creating an iOS game that allows the user to customize different parts of the main character with a color picker of three sliders. I'm wondering which would be better for the user experience, HSB or RGB? Have there been any user studies on this? I don't even know if it's a pressing issue that other people have asked but what is your preference on the idea? I'm leaning towards HSB because it seems to separate the different aspects of picking a color better.
Answer: HSB, because it adheres better to the 'natural' way people perceive color. RGB is a problem for most people. They don't get how to mix yellow from red and green, for instance.
That said, a color circle (H) with two sliders (S and B) may be better. But it takes up more space in the UI. Can you afford that?
Another option, which could make a lot of sense, is to limit the color options to a fixed set of colors. Because offering virtually limitless options could creates more problems than it solves.
Answer: I personally prefer selecting from a color wheel.  One advantage of a color wheel is that you can leave markers from other color choices visible on the wheel itself.  That way if I'm trying to come up with a complement, I can quickly look to the opposite side to pick the trim color.  Or I can gauge if my three main color choices are about 120 degrees apart.  You might even consider initially linking the primary and trim colors, making it even easier for the user to find a pleasantly complementing color.
I have also seen usable designs that use hexagonal tiles in a wheel shape, allowing the user to select from a discrete palette.
Another argument in favor of a wheel is that sliders and RGB or HSB numbers are a very "computeresque" experience, while a color wheel is a more human analog experience.  iPhones are all about designing the interface for the humans.
If there's a different reason you insist on three sliders, why do you feel you have to limit the user to either HSB or RGB?  I've seen plenty of applications that use a toggle to select the mode.
Comment: There isn't any particular reason I initially thought of three sliders, it's just what came to mind. I agree that it would definitely make more sense to go with something more human oriented. The hexagonal discrete palette is a very good idea.

iOS Color Picker User Experience


What is difference between INNER join and OUTER join

Question: Difference between inner and outer join. i am using two table and want to fetch data from both table so which type join we should use owning of that we can solve our problem
Answer: This is the best and simplest way to understand joins:

Credits go to the writer of this article HERE
Answer: Inner join - An inner join using either of the equivalent queries gives the intersection of the two tables, i.e. the two rows they have in common.
Left outer join -
A left outer join will give all rows in A, plus any common rows in B.
Full outer join -
A full outer join will give you the union of A and B, i.e. All the rows in A and all the rows in B. If something in A doesn't have a corresponding datum in B, then the B portion is null, and vice versa.
check this
Answer: INNER JOIN: Returns all rows when there is at least one match in BOTH tables
LEFT JOIN: Return all rows from the left table, and the matched rows from the right table
RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table
FULL JOIN: Return all rows when there is a match in ONE of the tables
Comment: I like the simple way that you have explained it.
Answer: Inner join matches tables on keys, but outer join matches keys just for one side.
For example when you use left outer join the query brings the whole left side table and matches the right side to the left table primary key and where there is not matched places null.


Energy eigenvalue of Hamiltonian operator

Question: Hamiltonian is the total energy of the system. Then, is its eigenvalue $E$ also total energy of the system? What is the difference between them? Both of them are energy.
Comment: The Hamiltonian is an operator. Its eigenvalues are numbers: they are the possible energies. In general it will have more than one.
Answer: For bound states:
$$\mathcal{H}\psi_n=E_n\psi_n$$
Where $\mathcal{H}$ is the Hamiltonion operator, $\psi_n$ a set of wave (eigen)functions and $E_n$ the corresponding eigenvalues.
If you're not familiar with eigenvalues, consider the simple quantum system of a single particle in a 1D box with infinite potential walls and zero potential inside the box.
The Hamiltonian operator of the system is:
$$\mathcal{H}=-\frac{\hbar^2}{2m}\frac{\operatorname{d^2} }{\operatorname{d}x^2}$$
The Schrödinger equation (SE) becomes:
$$-\frac{\hbar^2}{2m}\frac{\operatorname{d^2} }{\operatorname{d}x^2}\psi_n(x)=E_n\psi_n(x)$$
Solving, as per the link above, we get:
$$\psi_n(x)=C\sin\Big(\frac{n\pi x}{a}\Big)$$
Where $n=1,2,3,...$ and $a$ is the length of the box.
The eigenvalues (allowed energy levels) compute (as per the same link) to:
$$E_n=\frac{n^2\pi^2\hbar^2}{2ma^2}$$
Where $n=1,2,3,...$
$\psi_n(x)$ are the eigenfunctions of the SE and $E_n$ are its eigenvalues.
Answer: You need to review operators. if $\mathcal{H}$ is an Hamiltonian, and $\phi(t,x)$ is some wave vector, then
$\mathcal{H}\phi=\sum a_i\phi_i$
So, the operator is what you act with (operate) on a vector to change it to another vector, often represented as a sum of base vecotrs as I have written.
In the special case:
$\mathcal{H}\phi=E_i\phi_i$
$\phi$ is such a base vector, and $E$ the eigenvalue. Now we need to consider on the physical interpretation of the operator (this is more complicated to define), and in this case we say E is the energy - a scalar.
Comment: Then E ia the total enegy of the system @kabanus


Java LocalConnection Client

Question: I'd like to connect a Flash Player instance (AMF3) to a Java LocalConnection. I know how to implement the AMF3 spec, since I've done a lot of work with Red5, but I'm unsure how to navigate building the actual LocalConnection interface. There is C code provided here, but I can't speak C to save my life. Does anyone know of a Java implementation of the Flash Player LocalConnection?
Answer: Flash local connection use Shared Memory (see http://osflash.org/localconnection)
To use that in Java, (I suppose) you need write a JNI Wrapper to read it.
The other (easier) solution, is create a socket server (your Java Application) where the client (Flash Application) communicate with.
Answer: Not sure if this is useful to you, but there is a project called the merapi project that bridges between adobe air and java, not sure if you could adopt this for a flash player stand alone. See what you think.
Merapi Project

Java LocalConnection Client


Describe a main character

Question: I was wondering if you could help me with this:
I'm starting to write a book, but I don't really know how to describe the physic of the main character (in 1st person). I heard some techniques like, compare the character with herself when she was young (while watching an old pic), but I don't know if techniques like that look good in the story. Any advice? Cheers.
Answer: Your narrator compares herself to others.

I met Sandy at the coffee shop. I towered over her by a full head.

Cheap and simple: Your narrator looks at himself in a mirror.

In the bathroom, I ran a hand through my hair. Still black, just like my dad's, although thinner. He went gray early — nothing for me yet. I had my mom's blue eyes, which was surprising unless you knew I was mostly Welsh.

Straightforward: Your narrator describes himself.

I caught the guys in the bar looking. They had plenty to look at: tall, blonde, green-eyed, still pretty fit. Not a six-pack, maybe, but not a beer belly either.
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Answer: There are several techniques for doing this, as Lauren Ipsum illustrates, but consider that the first person narrator is also a character and how they narrate the story is part of how their character is formed in the story. So if the narrator describes their physical appearance, the fact that they are doing so says something profound -- and not necessarily very complimentary -- about their character. It may paint them as vain or self obsessed, for instance.
Also consider that by choosing a first person narrator, you are inviting the reader to adopt the narrator as a substitute self -- to see the world through that character's eyes, rather than to observe them directly. Therefore it may not matter much what they look like unless some aspect of their appearance is inescapably relevant to the story.
In short, it may not need doing, and will almost certainly have side effects that you may not want.

Describe a main character